Method and device for controlling the supply flow of reactants

Abstract

A computer-implemented method for the iterative control of a feed stream of a first reactant of a methanation process in a reactor, wherein the methanation process is carried out in the reactor and produces a product gas using a feed gas, wherein the feed gas comprises a first reactant and a second reactant, wherein the first reactant is one of dihydrogen and carbon oxide and the second reactant is the other of dihydrogen and carbon oxide, wherein the method comprises the following steps: - Initiating the calculation of a first setpoint for the supply flow of the first reactant (QH sp (t 2), QC sp (t 2)) and - Initiating the change in the supply flow of the first reactant according to the first setpoint of the supply flow of the first reactant (QH sp (t 2), QC sp (t 2)), where the calculation of the first setpoint of the supply flow of the first reactant (QH sp (t 2), QC sp (t 2)) is performed using initial information, where the initial information indicates whether an estimated value of an initial difference between an estimate of the feed ratio at a first control iteration and an initial requested value of the feed ratio (b) is available. req (t1)) is positive or negative in the first tax iteration, where the feed ratio is the ratio between the feed rate of the first reactant and the feed rate of the second reactant, and where the first information is obtained using a first set of measured physical quantities of the product gas. ( x C , P mea ( t 1 ) , x C , M mea ( t 1 ) ) is generated and whereby the first set of measured physical quantities ( x C , P mea ( t 1 ) , x C , M mea ( t 1 ) ) indicates the ratio between a first value of the amount of carbon oxide in the product gas at the first control iteration and a first value of the amount of methane in the product gas at the first control iteration.

Description

[0001] The present invention relates to a method and a device for controlling the feed flow of at least one reactant in a methanation process. In particular, the present invention relates to a method and a device for iteratively controlling the feed flow of at least one reactant in a methanation process, which is carried out, for example, in a reactor such as an industrial-scale reactor and / or the reactor arrangement according to the invention. In particular, the present invention relates to a method and a device for iteratively controlling the feed flow of at least one reactant in a methanation process in an aqueous culture medium containing biocatalysts such as archaea.

[0002] The methanization process of the present invention can be the methanization of carbon monoxide, CO + 3H₂ → CH₄ + H₂O, or the methanization of carbon dioxide, CO₂ + 4H₂ → CH₄ + 2H₂O. The methanization process according to the invention takes place in a reactor and produces a product gas using a feed gas. In the methanization of carbon monoxide, the feed gas consists, for example, of carbon monoxide and dihydrogen. In the methanization of carbon dioxide, the feed gas consists of carbon dioxide and dihydrogen. The product gas contains methane. The product gas can also contain carbon dioxide and / or dihydrogen.

[0003] Methane has the highest energy density per carbon atom among volatile hydrocarbons, and its energy conversion potential is far greater than that of any other natural gas. Therefore, methane represents a sustainable and renewable energy source and is increasingly replacing coal and other fossil fuels. Methanization processes are thus being used more and more for the generation of sustainable and renewable energy.

[0004] In this case, it is advantageous to maximize the amount of methane and / or minimize the amount of carbon dioxide and / or dihydrogen in the product gas. In particular, the amount of carbon dioxide and / or dihydrogen in the product gas generated by a methanization process should be kept within certain limits. Therefore, the prior art requires maximizing the amount of methane produced in a methanization process and / or minimizing the amount of carbon dioxide and / or dihydrogen in the product gas of a methanization process.

[0005] Methods for controlling the feed rate of reactants in methanation processes are known in the art. These methods aim to reduce the excess of the feed rate of reactants and / or to increase the quality of the product by increasing the amount of methane produced in the methanation process. The known control methods are based on direct measurements of the feed rate of the reactants. Typically, the measurements used in the art are characterized by a relatively low signal-to-noise ratio, which negatively affects the accuracy of the measurements and thus limits the efficiency of the known control methods.

[0006] Deviations between the measured value of the reactant feed flow and the actual amount of reactants fed into the reactors arise, for example, from measurement uncertainties, from unexpected and / or undetected fluctuations in the composition of the reaction feed gas and / or from inaccurate positioning of the means (e.g. control valves) for controlling the feed gas feed flow.

[0007] Furthermore, water is produced during methanation, which is usually discharged via the reactor outlet to prevent liquid accumulation within the reactor. The water production and subsequent reactor discharge lead to a continuous dilution and leaching of the dissolved substances. This leaching is compensated for by chemical dosing, for example, by adding suitable additive compounds to the reactor. Since the dynamics of the chemical dosing effect are generally slower than the ramp capacity of the process, any change in the dosing rate tends to have a delayed effect on the methanation process, thus influencing the extent of methanation.

[0008] At least some of these problems are at least partially solved by the invention of the present application, which relates to a computer-implemented method according to claim 1, to a data processing system according to claim 12, to a computer program product according to claim 14, and to a computer-readable storage medium according to claim 15. Embodiments of the invention are the subject of the dependent claims.

[0009] The present invention makes it possible, in particular, to monitor the extent of the methanation process and to control the quantity and ratios of the reactants in order to obtain a high-quality product stream with a minimal amount of unreacted reactants. In this way, suitable conditions for reaction catalysis are maintained in the reactor, and the development of the reactor's reactive capacity is supported.

[0010] The following notation is used throughout the entire specification: ◯ The indices C, H and M refer to carbon oxide, dihydrogen and methane respectively; ◯ The indices F and P refer to the feed gas and the product gas, respectively; ◯ The suffixes “req”, “mea”, “est” and “sp” refer to a requested value, a measured value, an estimated value and a target value of a quantity, respectively; ◯ the expression Q R (R = C, H) refers to the feed current of reactant R; and The expression b refers to the molar ratio between the injected dihydrogen stream of the feed gas and the injected carbon oxide stream of the feed gas, i.e., b = Q H / Q C .

[0011] Furthermore, the expression x refers to R,D(R = C, H, M and D = F, P) refers to the amount of compound R in the feed gas, relative to the feed gas (if D = F) or to the amount of compound R in the product gas, relative to the product gas (if D = P). Specifically, this amount is expressed as a molar percentage (mol:mol) of the gas stream feed gas (if D = F) or of the product gas (if D = P). The molar percentage can refer to the equivalent dry gas, i.e., the water vapor content is excluded from the feed gas (if D = F) or the product gas (if D = P).

[0012] A first aspect of the present invention relates to a computer-implemented method for iteratively controlling a feed stream of a first reactant in a methanation process in a reactor. The methanation process is carried out in the reactor and produces a product gas using a feed gas, wherein the feed gas comprises a first reactant and a second reactant.

[0013] According to the present invention, the first reactant is one of dihydrogen and one of carbon oxide, and the second reactant is the other of dihydrogen and carbon oxide. For example, the first reactant is a dihydrogen and the second reactant is a carbon oxide, e.g., carbon monoxide or carbon dioxide. Or the first reactant is a carbon oxide, e.g., carbon monoxide or carbon dioxide, and the second reactant is a dihydrogen. The product gas comprises, in particular, methane; for example, it consists of methane. The product gas can further comprise dihydrogen and / or carbon oxide, e.g., carbon monoxide and / or carbon dioxide.

[0014] The method according to the invention comprises at least the following steps: - Initiating the calculation of a first setpoint for the feed flow of the first reactant and - Initiating the change in the supply flow of the first reactant depending on the first setpoint of the supply flow of the first reactant.

[0015] The calculation of the first setpoint of the feed flow of the first reactant is performed using initial information, where the initial information indicates whether an estimated value of an initial difference between an estimate of the feed ratio at a first control iteration and a first requested value of the feed ratio at the first control iteration is positive or negative.

[0016] The feed ratio is the ratio between the feed rate of the first reactant and the feed rate of the second reactant, and the first information is generated using a first set of measured physical quantities of the product gas.

[0017] The first set of measured physical quantities shows the ratio between a first value of the amount of carbon oxide in the product gas at a first control iteration and a first value of the amount of methane in the product gas at the first control iteration.

[0018] The reactor can be located within an industrial plant, such as a power plant. The first and second reactants can be fed into the reactor together via a single gas supply. Alternatively, or in conjunction with the above, dihydrogen and carbon dioxide can be fed into the reactor separately, for example, via a first and a second gas supply, respectively. In particular, dihydrogen is preferably produced in a reactor from H₂O by a suitable electrolysis reaction using electrical energy. The electrical energy can, for example, originate from renewable energy sources. Carbon dioxide, such as carbon monoxide or carbon dioxide, can be produced in a biogas reactor and / or be an industrial gaseous waste product. The reactor can, in particular, contain an aqueous culture medium containing suitable methanogenic microorganisms, such as archaea, for converting the feed gas into the product gas.

[0019] In particular, the second reactant is the so-called leading reactant. The first reactant is determined based on the first reactant and the feed ratio. The leading reactant can depend on the configuration and / or the operational objective of the plant. For example, if the process for producing carbon dioxide (e.g., amine or water scrubbing, reversible absorption, membrane separation, cryogenation) limits the amount of carbon dioxide that can be fed into the reactor, then carbon dioxide is the leading reactant. If, on the other hand, the operational objective is to process a specific dihydrogen stream, determined, for example, by the amount of energy available for the electrolysis reaction, then dihydrogen is identified as the leading reactant.

[0020] The method for iteratively controlling the feed rate of the first reactant can comprise a multitude of control iterations. Each control iteration from the multitude of control iterations can be assigned to a corresponding time interval. For example, the first and second iterations (see below) are each assigned to a first and a second time interval, respectively. The first time interval is, for instance, disjoint from the second time interval and precedes it in time. In particular, the majority of control iterations include a first control iteration. The setpoint of the feed ratio in the initial control iteration can be equal to the requested value of the feed ratio in the initial control iteration.

[0021] In particular, each element of the first set of measured quantities is measured at a point in time within the first time interval and represents a measured value of a physical quantity of the product gas at the first iteration, i.e., at the aforementioned time. Hereafter, quantities relating to the first control iteration may be referred to as time-dependent t1. A quantity referred to as t1-dependent is, in particular, a quantity that is estimated, measured, and / or calculated during the first control iteration, although not necessarily at time t1.

[0022] In particular, the first set of measured quantities includes physical quantities that allow an estimation of the ratio (hereinafter also referred to as the "first ratio") between the first value of the amount of carbon dioxide in the product gas at the first control iteration and the first value of the amount of methane in the product gas at the first control iteration, and consists, for example, of these. The first set of measured quantities consists, for example, of a first measured value of the first ratio.

[0023] The first set of measured variables could, for example, be a first measured value for the amount of carbon oxide in the product gas during the first control iteration, e.g. sC,Pmea(t1), and an initial measurement of the amount of methane in the product gas during the first control iteration, sM,Pmea(t1), include. In this case, the first ratio is equal to sC,Pmea(t1) / sM,Pmea(t1).

[0024] Alternatively or in conjunction with the above, the first set of measured quantities can, for example, be a first measured value for the amount of carbon oxide relative to the product gas in the first iteration, xC,Pmea(t1), and an initial measurement of the amount of methane, relative to the product gas in the first iteration, xM,Pmea(t1), include; e.g., consist of. In this case, the first ratio is equal to xC,Pmea(t1) / xM,Pmea(t1).

[0025] The first piece of information can, for example, specify the estimated value of a first difference. The first piece of information can, for example, be encoded in the estimated value of the first difference. In particular, the estimated value of the first difference, d1est(t1), equal to the difference between a first estimate of the supply ratio, b est (t1), and the first requested value of the supply ratio b req (t1) be: d1est(t1)=best(t1)−breq(t1)

[0026] The first estimate of the supply ratio, b est (t1) is expressed at least in terms of the first set of measured physical quantities. In particular, the first estimate of the feed ratio is calculated using at least some elements of the first set of measured quantities and a suitable formula, based, for example, on the stoichiometry of the methanation process. The first estimate of the formula for the feed ratio may, for example, be given by: best(t1)=ρ×11+xC,Pmea(t1)xM,Pmea(t1) and / or best(t1)=ρ×11+sC,Pmea(t1)sM,Pmea(t1).

[0027] The coefficient ρ depends on the methanization process. In the case of carbon dioxide methanization, ρ = 4, while ρ = 3 in the case of carbon monoxide methanization.

[0028] In particular, the equations above are used when the amount of methane in the feed gas is negligible or zero, and when the amount of hydrogen in the product gas is negligible or zero. For example, the amount of methane in the feed gas is negligible if... xM,Fmea(t1) is smaller than one tenth and / or one hundredth of xC,Fmea(t1). Furthermore, the amount of hydrogen in the product gas is particularly negligible if xH,Pmea(t1) is smaller than one tenth and / or one hundredth of xM,Pmea(t1). The equations above can be used, for example, when the ratio (hereinafter also referred to as the "second ratio") between the value of the amount of dihydrogen in the product gas at the first control iteration and the value of the amount of methane in the product gas at the first control iteration is much smaller than ρ. In particular, the second ratio is much smaller than ρ if this ratio is less than one-tenth and / or one-hundredth of ρ.

[0029] The first estimate of the formula for the feed-in ratio could, for example, be as follows: best(t1)=ρ+1−xM,Pmea(t1)−xC,Pmea(t1)xM,Pmea(t1)1+xC,Pmea(t1)xM,Pmea(t1)

[0030] Equation (3) above is used in particular when the feed gas consists essentially of carbon oxide, methane, and dihydrogen. This is especially the case when the proportion of compounds other than carbon oxide, methane, and hydrogen in the product gas is less than one-tenth and / or one-hundredth of xM,Pmea(t1). The other compounds besides carbon oxide, methane and hydrogen can be nitrogen or oxygen.

[0031] In the present invention, the estimated feed ratio is calculated based on measurements of the product gas. The use of these measurements has a relatively high signal-to-noise ratio, leading to a more accurate estimation of the observed feed ratio and thus to more precise control of the methanation process. The estimated feed ratio within the scope of the present invention enables a real-time estimation of the actual ratio of reactants in the feed gas and thus a real-time estimation of the deviation between the requested feed ratio and the actual feed ratio entering the reactor.

[0032] According to one embodiment of the present invention, the first setpoint of the feed current of the first reactant is calculated as a function of a first setpoint of the feed ratio, wherein, in particular, if the estimate of the first difference is positive according to the first information, the first setpoint of the feed ratio is smaller than a second requested value of the feed ratio, and if, according to the first information, the estimate of the first difference is negative, the first setpoint of the feed ratio is larger than the second requested value of the feed ratio. The second requested value of the feed ratio is, in particular, the requested value of the feed ratio at a second control iteration, wherein the first control iteration precedes the second control iteration. For example, the second control iteration is the iteration that immediately follows the first control iteration.In particular, if, according to the first information, the estimated value of the first difference disappears, the first target value of the supply ratio is equal to the second requested value of the supply ratio.

[0033] The first setpoint for the supply flow of the first reactant is specifically the setpoint for the supply flow of the first reactant during the second control iteration. The calculation of the first setpoint for the supply flow of the first reactant is performed, for example, using a second value for the supply flow of the second reactant. This second value can be a measured, estimated, requested, and / or setpoint for the supply flow of the second reactant. For example, the second value for the supply flow of the second reactant is the setpoint for the supply flow of the second reactant during the second control iteration and / or the requested value for the supply flow of the second reactant during the second control iteration.

[0034] In the following, the quantities relating to the second control iteration can be described as time-dependent t2. A quantity described as t2-dependent is, in particular, a quantity that is estimated, measured, and / or calculated during the second control iteration, although not necessarily at time t2. If the first reactant is dihydrogen, e.g., if carbon dioxide is the leading reactant, the initial setpoint for the feed rate of the first reactant can be determined from the first setpoint. QHsp(t2) satisfy the following equation: QHsp(t2)=bsp(t2)×Qc(2)(t2), where b sp (t2) the first target value of the supply ratio is and QC(2)(t2) the second value of the feed rate of the second reactant. In particular, if the first reactant is dihydrogen, the first setpoint value of the feed rate of the first reactant can be calculated according to the first setpoint value of the feed ratio using Eq. (4).

[0035] If the first reactant is carbon oxide, e.g., if dihydrogen is the leading reactant, the first setpoint of the feed flow of the first reactant can be QCsp(t2) satisfy the following equation: QCsp(t2)=QH(2)(t2)bsp(t2), where QH(2)(t2) The second value is the feed rate of the second reactant. In particular, if the first reactant is carbon oxide, the first setpoint value of the feed rate of the first reactant can be calculated using Eq. (5).

[0036] The first requested value of the supply ratio, b req(t1) is, in particular, the feed ratio value requested and / or set by an operator of the plant's reactor during the first control iteration. Alternatively, the first requested feed ratio value can be estimated using a requested value of a quantity, e.g., the extent of the methanation process, where the requested value is the value requested by the operator during the first control iteration.

[0037] The second requested value of the supply ratio, b req (t2) can be the requested feed ratio value set by the operator during the second control iteration. Alternatively, the second requested feed ratio value can be estimated using a requested value of a parameter, e.g., the extent of the methanation process. This requested value is the value requested and / or set by the operator during the second control iteration.

[0038] According to the present invention, the step of initiating a change in the feed current of a reactant as a function of a setpoint of the feed current can include sending the setpoint to a computing device of the reactor and / or the power plant. In particular, the computing device controls a valve of the reactor or the power plant, wherein the valve regulates the feed current of the reactant into the reactor. This step can be achieved, in particular, by changing the feed current of the reactant according to the setpoint of the feed current. For example, changing the feed current of a reactant according to a setpoint of the feed current can include controlling a valve of the reactor or the power plant, wherein the valve regulates the feed current of the reactant into the reactor. For example, the valve is controlled such that it regulates the feed current of the reactant according to the setpoint of the feed current of the reactant.

[0039] According to one embodiment of the method of the present invention, the calculation of the first setpoint of the supply current of the first reactant comprises the calculation of a first value of a first function. The first function, f b is in particular an increasing function of the difference between an estimated supply ratio, b est , and a requested supply ratio b req , f b = f b (b est - b req In particular, the first value of the first function is the value of the first function at the estimated value of the first difference, i.e., the first value of the first function, f b,1 , even fb(d1req(t1)).

[0040] In particular, if the first reactant is dihydrogen, the first setpoint of the first reactant feed rate is a decreasing function of the first value of the first function, and if the first reactant is carbon oxide, the first setpoint of the first reactant feed rate is an increasing function of the first value of the first function.

[0041] If the first reactant is, for example, dihydrogen, then the first setpoint value of the feed rate of the first reactant is proportional to the second requested value of the feed ratio; and if the first reactant is carbon oxide, then the first setpoint value of the feed rate of the first reactant is inversely proportional to the second requested value of the feed ratio. In particular, in this embodiment, at least part of the first information is encoded in the first value of the first function.

[0042] For example, the first target value of the feed ratio of the feed, b sp (t2) be a decreasing function of the first linear combination, e.g. bsp(t2)=breq(t2)×(1−λ1). In particular, the first target value of the supply ratio, b sp (t2), be a first linear combination, λ1, be inversely proportional or have a hyperbolic dependence on λ1, e.g. bsp(t2)=breq(t2)1+λ1.

[0043] The first linear combination can include a first term, where the first term of the first linear combination is equal to the product between the first value f b,1 the first function and a first positive coefficient, c1.

[0044] For example, the first function, for each control iteration, shows the difference between an estimated feed ratio at that iteration and a requested feed ratio at that iteration, where the first function is an increasing function of that difference. Specifically, the first value of the first function is equal to the value of the first function at the estimated value of the first difference and represents the difference between the estimated feed ratio at the first iteration and the requested feed ratio at the first iteration.

[0045] In this embodiment, the setpoint value of the feed ratio is less sensitive to multiplicative or additive distortions that can affect the control of the flow rate of the first and / or the second reactant. This increases the accuracy of the calculation of the first setpoint for the feed rate of the first reactant.

[0046] For the purposes of the present invention, an increasing function of a variable is, in particular, a function that does not decrease as the variable increases. Furthermore, a decreasing function of a variable is, in particular, a function that does not increase with increasing value of the variable.

[0047] In particular, the first value of the first function is zero if the estimated feed ratio is equal to the requested feed ratio, it is positive if the estimated feed ratio is greater than the requested feed ratio, and it is negative if the estimated feed ratio is less than the requested feed ratio.

[0048] The first function can, for example, be the difference between the estimated and the requested supply ratio. In particular, the first function can be a function, e.g., a decreasing function, of the estimated supply ratio. req , to be, e.g. fb(best−breq,breq)=best−breqbreq=bestbreq−1.

[0049] In this case, the first value of the first function is equal to fb,1=d1est(t1)breq(t1)=best(t1)breq(t1)−1 and encodes the first piece of information. In particular, in this case, the first value of the first function is positive if the first difference is positive, and negative if the first difference is negative. In particular, according to Eq. (7), the first value of the first function is zero if the first difference vanishes.

[0050] According to one embodiment of the present invention, the calculation of the first setpoint for the feed rate of the first reactant comprises calculating an estimate of the time derivative of the first function at the first control iteration. The estimate of the time derivative of the first function is calculated using the first set of measured variables. In particular, if the first reactant is dihydrogen, the first setpoint for the feed rate of the first reactant is an increasing function of the estimate of the time derivative of the first function at the first control iteration, and if the first reactant is carbon oxide, the first setpoint for the feed rate of the first reactant is a decreasing function of the estimate of the time derivative of the first function at the first control iteration.

[0051] Alternatively, or in conjunction with the above, the calculation of the first setpoint for the feed rate of the first reactant includes the calculation of an estimate of the time integral of the first function during the first control iteration. The estimate of the time integral of the first function is calculated using the first set of measured quantities. Specifically, if the first reactant is dihydrogen, the first setpoint for the feed rate of the first reactant is a decreasing function of the estimate of the time integral of the first function, and if the first reactant is carbon oxide, the first setpoint for the feed rate of the first reactant is an increasing function of the estimate of the time integral of the first function.

[0052] For example, the first linear combination may include a second term, where the second term of the first linear combination is equal to the product between the estimated value D b,1The first linear combination corresponds to the time derivative of the first function at the first control iteration and a second negative coefficient c2. The first linear combination can include a third term, where the third term of the first linear combination is equal to the product of the estimate I. b,1 of the time integral of the first function at the first control iteration and a third positive coefficient c3.

[0053] The first linear combination could be, for example, the following: λ1=c1×fb,1orλ1=(c1×fb,1+c2×Db,1+c3×Ib,1)orλ1=(c1×fb,1+c2×Db,1)orλ1=(c1×fb,1+c3×Ib,1)

[0054] The first coefficient c1 can lie between 0.3 and 0.7, particularly between 0.4 and 0.6. For example, the second coefficient c2 lies between 0.3 min and 0.7 min, and particularly between 0.4 min and 0.6 min. The third coefficient c3 can lie between 2.0 min -1 and 3.0 min -1 and especially between 2.2 minutes -1and 2.7 min -1 lay.

[0055] The estimated value of the time derivative of the first function in the first control iteration, D b,1 , is in particular an estimate of the value of the time derivative of the first function at a time point in time that lies within the first time interval. For example, the estimated value D can be b,1 can be calculated numerically by using the first value of the first function.

[0056] The estimated value of the time integral of the first function in the first control iteration, I b,1 , is in particular an estimate of the value of the time integral of the first function at a time point that lies within the first time interval. For example, the estimated value I can be b,1 can be calculated numerically by using the first value of the first function.

[0057] The first value f b,1 The first function can be used with the help of b est(t1) is calculated, which is expressed by the first set of measured quantities. In this case, the estimated values ​​D are therefore b,1 and / or I b,1 calculated using the first set of measured quantities.

[0058] The estimated value I b,1 is only weakly dependent on the noise that can influence the measured quantities, since this noise has a vanishing expected value. Furthermore, the estimate I contains b,1 Information about the value of the first function in control iterations that occur before the first control iteration. Ultimately, the estimated value therefore contains I. b,1 Information about the trend of the difference between the estimated and requested supply ratio is more stable against momentary fluctuations in this difference. The use of the estimated value I b,1The calculation of the first target value of the supply ratio stabilizes and / or increases the robustness of the calculation of the stated target value.

[0059] The estimated value D b,1 The time derivative of the first function takes into account the rate of change of the first function. The dependence of the first setpoint of the supply current of the first reactant on D b,1 This reduces the overshoot of the first reactant feed rate. In this way, the deviation between the value of the first reactant feed rate and the requested value of this feed rate is reduced. The methanation process therefore essentially runs at the requested operating point, thereby increasing the predictability of the process result.

[0060] One embodiment of the present invention further comprises the following steps: - Initiating the calculation of a second setpoint for the supply flow of the second reactant, wherein the calculation of the second setpoint for the supply flow of the second reactant is performed using at least one first setpoint for the supply flow of the second reactant and a ramp rate for the supply flow of the second reactant; and - Initiation of the change in the supply flow of the second reactant according to the second setpoint of the supply flow of the second reactant.

[0061] If the first setpoint value of the supply current for the second reactant is greater than the first requested value of the supply current for the second reactant, the second setpoint value of the supply current for the second reactant is less than the first setpoint value of the supply current for the second reactant. Conversely, if the first setpoint value of the supply current for the second reactant is less than the first requested value of the supply current for the second reactant, the second setpoint value of the supply current for the second reactant is greater than the first setpoint value of the supply current for the second reactant.

[0062] In particular, if the first setpoint of the supply flow of the second reactant is equal to the first requested value of the supply flow of the second reactant, then the second setpoint of the supply flow of the second reactant is equal to the first setpoint of the supply flow of the second reactant.

[0063] The first setpoint of the supply flow of the second reactant is, in particular, the setpoint QR2sp(t1) of the supply flow rate of the second reactant during the first control iteration. The second setpoint value of the supply flow rate of the second reactant is, for example, the setpoint. QR2sp(t2) of the supply flow of the second reactant during the second control iteration. Furthermore, the first requested value of the supply flow of the second reactant can be the requested value. QR2req(t2), of the supply current during the second control iteration. For example, the second setpoint of the supply current of the second reactant, QR2sp(t2), calculated according to the following equation: QR2sp(t2)=QR2sp(t1)+uR2,F×sign(QR2req(t2)−QR2sp(t1))×(t2−t1), where sign(x) is equal to 1 if x > 0, equal to -1 if x < 0, and 0 if x = 0. u R2,FR2 is the ramp rate of the feed stream of the second reactant. If the second reactant is dihydrogen, R2 in the equation above is replaced by H. If the second reactant is carbon dioxide, R2 is replaced by C. The ramp rate is a fraction of the reactor capacity per minute. The ramp rate can be between 3% and 14% of the reactor capacity per minute, and more specifically between 7% and 10%. For example, the ramp rate can be approximately 3.3% or 13.3% of the reactor capacity per minute. For example, u C,F = 1 Nm 3 - Carbon dioxide / h / min and / or u H,F = 4 Nm -H 3 2 / h / min.

[0064] In this embodiment, the feed rate of the second reactant is changed stepwise to reduce the difference between the setpoint and the requested feed rate of the second reactant. This stepwise change of the setpoint prevents a reduction in the amount of gas available to the methanogenic microorganisms in the culture medium for conversion.

[0065] One embodiment of the method according to the invention comprises the step of initiating the change of the supply current of the second reactant according to a setpoint of the supply current of the second reactant, wherein the setpoint of the supply current of the second reactant is equal to the first requested value of the supply current of the second reactant.

[0066] In one embodiment of the present invention, the calculation of the first setpoint of the feed flow of the first reactant is carried out using a second piece of information, wherein the second piece of information indicates whether an estimated value of a second difference between an estimate of the extent of the methanation process at the first control iteration and a requested value of the extent of the methanation process at the first control iteration is positive or negative.

[0067] The second piece of information can, for example, specify the estimated value of the second difference. The second piece of information can, for example, be encoded in the estimated value of the second difference. In particular, the estimated value of the second difference, d2est(t1), equal to the difference between an estimated value of the extent of the methanization process y est (t1) and the requested value of the extent of the methanization process, y req (t1), his: d2est(t1)=yest(t1)−yreq(t1).

[0068] The first estimate for the extent of the methanization process, y est (t1) is expressed at least in the form of the first series of measured physical quantities. In particular, y est (t1) is calculated by using at least some elements of the first set of measured quantities and a suitable formula, e.g., based on the stoichiometry of the methanation process. The estimated extent of the methanation process could, for example, be as follows: yest(t1)=11+xC,Pmea(t1)xM,Pmea(t1) and / or yest(t1)=11+sC,Pmea(t1)sM,Pmea(t1).

[0069] The above equations are used in particular when the amount of methane in the feed gas is negligible or zero.

[0070] The estimated feed ratio is calculated based on measurements of the product gas. These measurements have a relatively high signal-to-noise ratio, leading to a more accurate estimation of the observed extent of the methanation process and thus to more precise control of the methanation process.

[0071] Another embodiment of the present invention comprises the following steps: - Initiating the calculation of a third setpoint for the supply flow of the second reactant, wherein the calculation of the third setpoint for the supply flow of the second reactant is performed using a first reference value for the supply flow of the second reactant at the first control iteration and a first value for the supply flow of the second reactant; and - Initiation of the change in the supply flow of the second reactant depending on the third setpoint of the supply flow of the second reactant.

[0072] The third setpoint for the supply flow of the second reactant is equal to the minimum between a second reference value for the supply flow of the second reactant at the second control iteration and the first value of the supply flow of the second reactant.

[0073] In particular, if, according to the second piece of information, the estimated value of the second difference is positive, the second reference value of the supply current of the second reactant is greater than the first reference value of the supply current of the second reactant, and if, according to the second piece of information, the estimated value of the second difference is negative, the second reference value of the supply current of the second reactant is less than the first reference value of the supply current of the second reactant.

[0074] In particular, if, according to the second piece of information, the estimated value of the second difference vanishes, the second reference value of the supply current of the second reactant is equal to the first reference value of the supply current of the second reactant.

[0075] The third setpoint for the supply flow of the second reactant can be the setpoint for the supply flow of the second reactant during the second control iteration. Specifically, the second reference value for the supply flow of the second reactant is an upper limit for the third setpoint for the supply flow of the second reactant during the second control iteration. Furthermore, the first reference value for the supply flow of the second reactant can be an upper limit for a setpoint for the supply flow of the second reactant during the first control iteration.

[0076] The third setpoint for the feed rate of the second reactant depends on whether the estimated process extent is less than the requested extent, i.e., the process capacity is limited, or whether the estimated process extent is greater than the requested extent, i.e., the process capacity is not limited. In this embodiment, the third setpoint for the feed rate of the second reactant is adjusted according to the discrepancy between the estimated and requested process extent, so that the feed rate of the most soluble reactant is maintained above the requested feed rate and / or the amount of dihydrogen in the product gas is reduced. The feed rate of the second reactant converges to a rate compatible with the current process capacity.Furthermore, in situations where reaction capacity is limited, the target value of the leading reactant is limited according to the current conversion capacity of the process until the desired capacity is restored or reached. This mitigates the adverse effects of fluctuations in catalyst performance and / or process conditions (e.g., temperature, excess reactants, additive dosage) and / or accelerates the restoration of process performance.

[0077] For example, the third setpoint of the supply flow of the second reactant, QR2sp(t2) calculated according to the following equation: QR2sp(t2)=min(QR2ref(t2),QR2(1)),

[0078] with regard to the second reference value of the feed stream of the second reactant, QR2ref(t2), and the first value of the feed stream of the second reactant, QR2(1).

[0079] The extent of the methanization process is defined, in particular, as the ratio between the amount of carbon dioxide in the feed gas that is converted to methane and the amount of carbon dioxide in the feed gas. The requested value for the degree of methanization is, in particular, the value requested and / or set by an operator on the first control loop.

[0080] The first value of the feed flow of the second reactant can be the first requested value of the feed flow of the second reactant during the second control iteration. Specifically, the first value of the feed flow of the second reactant is the value of the feed flow of the second reactant that is requested and / or set by an operator of the plant's reactor during the second control iteration.

[0081] According to one embodiment of the present invention, the first value of the supply current of the second reactant is a function of the first setpoint of the supply current of the second reactant, the first requested value of the supply current of the second reactant, and the ramp rate of the supply current of the second reactant.

[0082] In particular, if the first setpoint value of the supply current of the second reactant is greater than the first requested value of the supply current of the second reactant, the first value of the supply current of the second reactant is less than the first setpoint value of the supply current of the second reactant. Conversely, if the first setpoint value of the supply current of the second reactant is less than the first requested value of the supply current of the second reactant, the first value of the supply current of the second reactant is greater than the first setpoint value of the supply current of the second reactant.

[0083] In particular, if the first setpoint of the supply flow of the second reactant is equal to the first requested value of the supply flow of the second reactant, then the first value of the supply flow of the second reactant is equal to the first setpoint of the supply flow of the second reactant. For example, the first value of the supply flow of the second reactant QR2(1) using Eq. (9) with the substitution QR2sp(t2)→QR2(1) be calculated.

[0084] According to one embodiment of the present invention, the calculation of the first setpoint of the supply current of the first reactant comprises the calculation of a first value of a second function. The second function, f y , is in particular an increasing function of the difference between an estimated extent of the methanization process, y est , and a reference level of the methanization process y req e.g. f y = f y (yest - y Teq ). Furthermore, the first value f y,1 The value of the second function at the estimated value of the second difference should be the first value of the first function f. y,1 , is the same fy(d2est(t1)). In particular, the second reference value of the supply current of the second reactant can be proportional to the first reference value of the supply current of the second reactant and an increasing function of the first value of the second function.

[0085] For example, the second reference value of the feed current of the second reactant can be QR2ref(t2) proportional to the first reference value of the feed flow of the second reactant, QR2ref(t1), and a second linear combination, λ2, e.g. QR2ref(t2)=λ2×QR2ref(t1).

[0086] The second linear combination includes a first term, where the first term of the second linear combination is equal to the product of the first value of the second function and a positive fourth coefficient, c4. The fourth coefficient can depend on the sign of the difference between the estimated extent of the methanation process and the desired extent of the methanation process.

[0087] For example, the second function, for each control iteration, shows the difference between an estimated extent of the methanation process at that iteration and a requested extent of the methanation process at that iteration, where the second function is an increasing function of that difference. Specifically, the first value of the second function is equal to the value of the second function at the second difference and represents the difference between the estimated extent of the methanation process at the first iteration and the requested extent of the methanation process at the first iteration.

[0088] In particular, the reference values ​​for the feed rate of the second reactant represent an upper limit for the setpoint values ​​of this feed rate, enabling the setpoint values ​​of the second reactant feed rate to be kept within a range that provides a process conversion capacity close to the observed conversion capacity. In this embodiment, the setpoint value of the feed rate is updated during the second control iteration using the setpoint value of the feed rate from the first control iteration. The update of the reference value also depends on information indicating the sign of the difference between the estimated and the requested extent of the process; that is, it indicates whether the process capacity is limited.In this way, the update of the reference value takes into account the fact that the amplitude of the variation in the difference between the estimated and the requested process level typically depends on whether the process capacity is limited or not. Since the system normally operates at a relatively high utilization rate, e.g., above 90%, the fluctuations in the difference between the estimated and the requested process utilization are greater in the case of a limited process capacity than the fluctuations in this difference in the case of an unlimited process capacity.

[0089] In particular, the first value of the second function is zero if the estimate of the second difference vanishes, is positive if the estimate of the second difference is positive, and is negative if the estimate of the second difference is negative.

[0090] The second function can, for example, be the difference between the estimated extent of the methanization process and the requested extent of the methanization process. In particular, the second function can be a function, e.g., a decreasing function, of the requested extent of the methanization process, y. req , to be, e.g. fy(yest−yreq,yreq)=yest−yreqyreq=yestyreq−1.

[0091] In this case, the first value of the second function is equal to fy,1=d2est(t1)yreq(t1)=yest(t1)yreq(t1)−1 and encodes the second piece of information. In particular, in this case, the first value of the second function is positive if the second difference is positive, and it is negative if the second difference is negative. In particular, according to Eq. (14), the first value of the second function is zero if the second difference vanishes.

[0092] According to one embodiment of the present invention, the calculation of the first setpoint of the supply current of the first reactant comprises the calculation of an estimated value of a time derivative of the second function during the first control iteration, wherein the estimated value of the time derivative of the second function is calculated using the first set of measured quantities. In particular, the second reference value of the supply current of the second reactant can be an increasing function of the estimated value of the time derivative of the second function.

[0093] Alternatively, or in conjunction with the above, the calculation of the first setpoint for the first reactant's supply flow can include calculating an estimate of the time integral of the second function during the first control iteration. The estimated time integral of the second function is calculated using the first set of measured quantities. For example, the second reference value for the second reactant's supply flow can be an increasing function of the estimated time integral of the second function during the first control iteration.

[0094] The second linear combination can, for example, include a second term equal to the product of the estimated value of the time derivative of the second function, D. y,1, and corresponds to a positive fifth coefficient, c5. The fifth coefficient depends on the sign of the difference between the estimated extent of the methanation process and the desired value of the extent of the methanation process. The second linear combination may, for example, contain a third term equal to the product of the estimated time integral of the second function, I y,1 and corresponds to a positive sixth coefficient, c6. The sixth coefficient depends on the sign of the difference between the estimated extent of the methanation process and the desired extent of the methanation process.

[0095] The second linear combination could be, for example, the same: λ2=1+c4×fy,1,orλ2=1+(c4×fy,1+c5×Dy,1+c6×Iy,1),orλ2=1+(c4×fy,1+c5×Dy,1),orλ2=1+(c4×fy,1+c6×Iy,1).

[0096] The fourth coefficient can depend on the first value of the first function, f y,1 e.g. c4=c4+×Θ0(fy,1)+c4−×Θ0(−fy,1), where Θ0 is the Heaviside step function with 0,(0) = 0. The coefficient c4+ It can range between 0.001 and 0.005, and especially between 0.002 and 0.004. For example, c4+ between 0.05 and 0.3, and in particular between 0.1 and 0.2. The fifth and / or sixth coefficient can be expressed in the form of the fourth coefficient, c j = c4 × ĉ j with j = 5, 6. The coefficient ĉ5 can lie between 0.5 min and 1.5 min, in particular between 0.7 min and 1.2 min. The coefficient ĉ6 can lie between 0.05 min -1 and 0.15 min -1 , especially between 0.07 min -1 and 0.12 min -1 lay.

[0097] The estimated value I y,1is only weakly dependent on the noise that can influence the measured quantities, since this noise has a vanishing expected value. Furthermore, the estimate I contains y,1 Information about the value of the second function in control iterations that occur before the first control iteration. Ultimately, the estimated value I contains y,1 This provides information about the progression of the difference between the estimated and the requested extent of the process and is more stable against momentary fluctuations in this difference. The use of the estimated value I y,1 The calculation of the second reference value for the feed current of the second reactant stabilizes and / or increases the robustness of the calculation of the stated setpoint. The estimated value D y,1 The time derivative of the second function takes into account the rate of change of the second function. The dependence of the second setpoint of the supply current of the second reactant on D y,1reduces the overshoot of the reference value of the feed current of the second reactant, thereby reducing the deviation between the first and second reference values ​​of the feed current of the second reactant.

[0098] The estimated value D y,1 This is, in particular, an estimate of the value of the time derivative of the second function at a time point in time that lies within the first time interval. For example, the estimated value D can be y,1 can be calculated numerically by using the first value of the second function.

[0099] The estimated value I y,1 In particular, this is an estimate of the value of the time integral of the second function at a time point contained in the first time interval. For example, the estimated value I y,1 can be calculated numerically by using the first value of the second function. The first value f y,1 The second function is achieved by using y est(t1) is calculated, which is expressed by the first set of measured quantities. Therefore, in this case, the estimated values ​​D y,1 and / or I y,1 calculated using the first set of measured quantities.

[0100] According to one embodiment of the present invention, the calculation of the first setpoint of the supply current of the first reactant comprises the calculation of a first value of a third function. The third function, g y , is an increasing function of the difference between the estimated extent of the methanization process, y est , and the required extent of the methanization process, y req , g y = g y (y est - y req In particular, the first value of the third function is the value of the third function at the second difference, e.g., the first value of the third function is g. y,1 , even gy(d2est(t1)). The second requested value of the supply ratio can be proportional to the first requested value of the supply ratio and a decreasing function of the first value of the third function.

[0101] In particular, if the first reactant is dihydrogen, the first setpoint of the first reactant feed rate is a decreasing function of the first value of the third function, and if the first reactant is carbon oxide, the first setpoint of the first reactant feed rate is an increasing function of the first value of the third function.

[0102] For example, the dependence of the second requested value of the supply ratio on the first requested value of the supply current and the first value of the third function of the supply ratio is such that the second requested value of the supply ratio lies between a minimum value b min and a maximum value b maxthe supply ratio. The actual value of b min and b max depends on the characteristics of the reactor and / or the power plant. In the case of methanization processes, b min and b max usually equal to 4 or 4.2.

[0103] For example, the second requested value of the supply ratio, b req (t2), be directly proportional to a third linear combination, λ3, e.g. breq(t2)=breq(t1)×λ3.

[0104] The third linear combination can include a first term, where the first term of the third linear combination is equal to the product between the first value g. y,1 the third function and a seventh coefficient, c7.

[0105] For example, the third function, for each control iteration, shows the difference between the estimated feed rate at that iteration and the desired feed rate at that iteration, where the third function is an increasing function of this difference. Specifically, the first value of the third function is equal to the value of the third function at the second difference and shows the difference between the estimated extent of the methanation process at the first iteration and the requested extent of the methanation process at the first iteration.

[0106] In this embodiment, the requested feed ratio value is adjusted in real time during the second control iteration relative to the requested feed ratio value during the first control iteration, ensuring that no amounts of reactants are added to the culture medium exceeding its conversion capacity. Furthermore, if the methanation process capacity is not limited, this embodiment allows for a reduction in the ratio between the dihydrogen and carbon dioxide feed streams, thereby decreasing the excess of the less soluble reactant. Conversely, if the methanation process capacity is limited, this ratio is increased to increase the amount of the less soluble reactant in the reactor.Increasing the amount of the less soluble reactant leads to an increase in the amount of reactants that can react to methanize, thereby increasing the extent of methanization. Furthermore, increasing the amount of the less soluble reactant can reduce the amount of carbon dioxide that does not enter the methanization process and accumulates in the reactor.

[0107] The third function could, for example, be the difference between the estimated extent of the methanization process and the requested extent of the methanization process. In particular, the third function could be a function of y. req be, for example gy(yest−yreq,yreq)=max(yreq−1,fy(yest−yreq,yreq))1−yreq+g0.

[0108] The term g0 is a distortion that increases the second requested value of the feed ratio in the case of small values ​​of g. y,1 prevented. For example, g0 = (1 - yreq ) / 2.

[0109] In one embodiment of the present invention, the calculation of the first setpoint of the feed current of the first reactant comprises the calculation of an estimate of a time derivative of the third function during the first control iteration, wherein the estimate of the time derivative of the third function is calculated using the first set of measured variables. In particular, if the first reactant is dihydrogen, the first setpoint of the feed current of the first reactant is a decreasing function of the estimate of the time derivative of the third function, and if the first reactant is carbon oxide, the first setpoint of the feed current of the first reactant is an increasing function of the estimate of the time derivative of the third function.

[0110] Alternatively, or in conjunction with the above, the calculation of the first setpoint for the first reactant feed rate can include calculating an estimate of the time integral of the third function during the first control iteration, where the estimate of the time integral of the third function is calculated using the first set of measured quantities. Specifically, if the first reactant is dihydrogen, the first setpoint for the first reactant feed rate is a decreasing function of the estimate of the time integral of the third function, and if the first reactant is carbon oxide, the first setpoint for the first reactant feed rate is an increasing function of the estimate of the time integral of the third function.

[0111] The third linear combination can, for example, include a second term equal to the product of the estimated value of the time derivative of the third function, D̂ y,1'and an eighth coefficient, c8. For example, the third linear combination can include a third term, where the third term is equal to the product of the estimated value of the time integral of the second function, Î y,1 and a ninth coefficient, c9.

[0112] The third linear combination could, for example, be the following: λ3=1+α3×λ^3.

[0113] The coefficient α3 can be determined from the coefficient λ̂3 of the g. y,1 depend, e.g.: α3=[breq(t1)−bminbreq(t1)×Θ0(λ^3)+bmax−breq(t1)breq(t1)×Θ1(−λ^3)], where Θ1 is the Heaviside function, where Θ1(0) = 1, and b req (t1) is the first requested value of the supply ratio. The coefficient λ̂3 can be equal to the following: λ^3=c7×gy,1,orλ^3=(c7×gy,1+c8×D^y,1+c9×I^y,1),orλ^3=(c7×gy,1+c8×D^y,1),orλ^3=(c7×gy,1+c9×I^y,1).

[0114] The seventh coefficient, c7, can lie between -510 and -490, and in particular between -505 and -495. Specifically, the fifth and / or sixth coefficients can be expressed in terms of the seventh coefficient, c j = c7 × ĉ j , where j = 8, 9. The coefficient ĉ8 can lie between 0.01 min and 0.15 min, in particular between 0.07 min and 0.15 min. The coefficient ĉ9 can lie between 0.5 min -1 and 1.5 minutes -1 , especially between 0.7 min -1 and 1.2 minutes -1 lay.

[0115] The estimated value Î y,1 is weakly dependent on the noise that can influence the measured quantities, since this noise has a vanishing expectation value. Furthermore, Î y,1 Information about the value of the third function in tax iterations that occur before the first tax iteration. Thus, the estimated value Î contains y,1Information about the progression of the difference between the estimated and the requested extent of the process is more stable against momentary fluctuations in this difference. The use of the estimated value Î y,1 The calculation of the second requested value of the feed ratio stabilizes and / or increases the robustness of the calculation of the requested value and thus of the target value of the feed ratio. Furthermore, the estimated value D̂ takes into account y,1 The time derivative of the third function is the rate of change of the third function. The dependence of the requested value of the supply ratio on D̂ b,1 This reduces the overshoot of this value and thus the deviation between the first and second target values ​​of the feed ratio.

[0116] The estimated value D̂ y,1In particular, it is an estimate of the value of the time derivative of the third function at a time point in time that lies within the first time interval. The estimated value Î y,1 In particular, this is an estimate of the value of the time integral of the third function at a time point that is contained in the first time interval.

[0117] In one embodiment of the present invention, the calculation of the first setpoint for the supply current of the first reactant comprises the generation of the second information using the first set of measured physical quantities.

[0118] In particular, generating the second piece of information involves calculating the estimated value of the second difference using the first set of measured physical quantities, e.g., via Eq. (10). The calculation of the estimated value of the second difference may, for example, include calculating the estimated value of the extent of the methanation process using the first set of measured physical quantities. For example, the estimated value of the extent of the methanation process is calculated using Eq. (11) above and / or Eq. (24), which is disclosed below.

[0119] In a further embodiment of the present invention, the calculation of the first setpoint of the feed flow of the first reactant comprises the calculation of the second reference value of the feed flow of the second reactant, wherein the calculation of the second reference value of the feed flow of the second reactant is performed using the first reference value of the feed flow of the second reactant, the estimated extent of the methanation process, and the requested value of the extent of the methanation process. For example, the second reference value of the feed flow of the second reactant is calculated using Eq. (13) in combination with one of the formulas from Eq. (15).

[0120] According to one embodiment of the present invention, the first set of measured physical quantities is also an indicator of the ratio between a first value of the amount of dihydrogen in the product gas at the first control iteration and the first value of the amount of methane in the product gas at the first control iteration.

[0121] In particular, each element of the first set of measured quantities is measured at a time point within the first time interval and represents a measured value of a physical quantity of the product gas at the first iteration, i.e., at the aforementioned time point. Hereafter, the quantities relating to the first control iteration and the second control iteration can be described as dependent on times t1 and t2, respectively. Times t1 and t2 are contained within the first and second time intervals, respectively.

[0122] In particular, the first set of measurements includes physical quantities that allow an estimation of the second ratio. For example, the first set of measurements includes a first measurement of the first ratio. For example, the first set of measurements may include a first measurement of the amount of dihydrogen in the product gas during the first control iteration. sH,Pmea(t1), and the first measured value of the amount of methane in the product gas during the first control iteration, sM,Pmea(t1), include. In this case, the second ratio is equal to sH,Pmea(t1) / sM,Pmea(t1). Alternatively or in conjunction with the above, the first set of measured quantities can provide a first measurement of the amount of dihydrogen, relative to the product gas, in the first iteration, xH,Pmea(t1), and an initial measurement for the amount of methane, based on the product gas in the first iteration, xM,Pmea(t1), include. In this case, the second ratio is equal to xC,Pmea(t1) / xM,Pmea(t1).

[0123] The first estimate of the feed ratio could be, for example, as follows: best(t1)=[ρ+xH,Pmea(t1)xM,Pmea(t1)]×11+xC,Pmea(t1)xM,Pmea(t1).

[0124] The above equation is used in particular when the amount of methane in the feed gas is negligible or zero. The first estimate of the feed-in / feed ratio can be expressed in terms of the amounts of dihydrogen, methane, and carbon dioxide in the product gas using equation (22), with the substitution x. mea → s mea .

[0125] Alternatively, or in conjunction with the above, the first piece of information is generated using a second set of measured physical quantities of the feed gas. This second set of measured physical quantities of the feed gas is an indicator of the ratio between a first value of the methane content in the feed gas during the first control iteration and a first value of the carbon dioxide content in the feed gas during the first control iteration.

[0126] In particular, each element of the second set of measurements is measured at a point in time within the first time interval and represents a measured value of a physical quantity of the feed gas at the first iteration, i.e., at the aforementioned time. The second set of measurements includes, for example, physical quantities that allow an estimation of the ratio (hereinafter also referred to as the "third ratio") between the first value of the amount of methane in the feed gas at the first control iteration and the first value of the amount of carbon dioxide in the product gas at the first control iteration. The first set of measurements includes, for example, a first measured value of the third ratio.

[0127] For example, the first set of measured values ​​can include an initial measurement of the methane quantity in the feed gas during the first control iteration, e.g., consist of an initial measurement of the methane quantity in the feed gas during the first control iteration. sM,Fmea(t1), and an initial measurement for the amount of carbon oxide in the feed gas during the first control iteration, sC,Fmea(t1). In this case, the third ratio is equal sM,Fmea(t1) / sC,Fmea(t1). Alternatively or in conjunction with the above, the first set of measured quantities can provide a first measured value of the amount of methane, relative to the feed gas in the first iteration, xM,Fmea(t1), and an initial measurement for the amount of carbon oxide, relative to the feed gas in the first iteration, xC,Fmea(t1), include, for example, consist of. In this case, the third ratio is equal to xM,Fmea(t1) / xC,Fmea(t1).

[0128] The first estimate of the supply ratio can be given as follows: best(t1)=[ρ+xH,Pmea(t1)xM,Pmea(t1)]×1−xC,Pmea(t1)xM,Pmea(t1)×xM,Fmea(t1)xC,Fm ea(t1)1+xC,Pmea(t1)xM,Pmea(t1)+xH,Pmea(t1)xM,Pmea(t1)×xM,Fmea(t1)xC,Fmea(t1).

[0129] The first estimate of the feed ratio can be expressed by the amount of dihydrogen, methane and carbon oxide in the product gas and in the feed gas by substituting Eq. (23) for x. mea → s mea is used.

[0130] In one embodiment of the present invention, the estimated extent of the methanization process is expressed at least in terms of the second group of measured physical quantities of the feed gas. For example, the estimated extent of the methanization process can be expressed as follows: yest(t1)=1−xC,Pmea(t1)xM,Pmea(t1)×xM,Fmea(t1)xC,Fmea(t1)1+xC,Pmea(t1)xM,Pmea(t1).

[0131] One embodiment of the present invention further comprises the step of initiating the measurement of at least one measured physical quantity, e.g. each measured quantity, of the first set of measured physical quantities.

[0132] The step of initiating the measurement of the measured physical quantity of the first set of measured physical quantities can consist of instructing a computing device of the reactor and / or the power plant to measure said quantity. In particular, the computing device controls a gas analyzer of the reactor, the analyzer being configured to analyze the composition of the product gas. This step can be accomplished, in particular, by instructing the gas analyzer to measure the measured physical quantity of the first set of measured physical quantities.

[0133] Another embodiment of the present invention comprises the step of initiating the measurement of at least one measured physical quantity, e.g. each measured quantity, of the second set of measured physical quantities.

[0134] The step of initiating the measurement of the measured physical quantity of the second set of measured physical quantities can consist of instructing a computing device of the reactor and / or the power plant to measure said quantity. In particular, the computing device controls a gas analyzer of the reactor, the analyzer being configured to analyze the composition of the feed gas. This step can be carried out, in particular, by instructing the gas analyzer to measure the measured physical quantity of the first set of measured physical quantities.

[0135] The step of initiating the measurement of a measured physical quantity (e.g., a measured physical quantity of the first set or the second set) can be carried out by measuring this quantity. The computing device tasked with measuring a physical quantity (e.g., a physical quantity of the first set or the second set) and the computing device performing a method according to the invention can be located at different locations.

[0136] According to one embodiment of the invention, calculating the first setpoint of the feed current of the first reactant includes generating the first information using the first set of measured physical quantities. In particular, generating the first information includes calculating the estimated value of the first difference using the first set of measured physical quantities, e.g., via Eq. (1). For example, calculating the estimated value of the first difference includes calculating the first estimated value of the feed ratio using the first set of measured physical quantities. The first estimated value of the feed ratio can be calculated using one of the formulas from Eq. (2), Eq. (3), Eq. (22), and / or Eq. (23).

[0137] According to one embodiment of the present invention, the calculation of the first setpoint of the feed current of the first reactant includes the calculation of the first setpoint of the feed ratio. The calculation of the first setpoint of the feed ratio can be performed using the first estimated value of the feed ratio, the first requested value of the feed ratio, and the second requested value of the feed ratio. For example, the calculation of the first setpoint of the feed ratio is performed by using Eq. (6) in combination with one of the formulas from Eq. (8).

[0138] In particular, the first setpoint value of the feed rate of the first reactant is calculated using the first setpoint value of the feed ratio and the first measured value of the feed rate of the second reactant. For example, if the first reactant is dihydrogen, the first setpoint value of the feed rate of the first reactant can be calculated using equation (4). If the first reactant is carbon oxide, e.g., carbon monoxide or carbon dioxide, the first setpoint value of the feed rate of the first reactant can be calculated using equation (5).

[0139] The calculation of the first setpoint for the feed rate of the first reactant may include the calculation of the second requested feed ratio value using the first requested feed ratio value. For example, the calculation of the second requested feed ratio value is performed using Eq. (17) in combination with Eq. (19), Eq. (20), and one of the formulas in Eq. (21).

[0140] A second aspect of the present invention relates to a method for iteratively controlling the dosing rate of an additive compound in a methanation process in a reactor. According to this aspect, the methanation process is carried out in a first culture medium in the reactor and produces a product gas using a feed gas. In particular, the first culture medium consists of water and the additive compound, and the feed gas consists of dihydrogen and carbon dioxide. The method according to the second aspect of the present invention comprises at least the following steps: - Initiating the calculation of a first target value of a dosage rate of the additive compound, wherein the calculation of the first target value of the dosage rate of the additive compound is carried out using a value of the concentration, n ad, and a setpoint for the carbon oxide supply flow is determined, such that the first setpoint for the dosage rate of the additive compound is suitable to compensate for water runoff in the first culture medium; and - Initiating the change in the dosing rate of the auxiliary connection according to the first setpoint of the supply current of the auxiliary connection.

[0141] The first setpoint for the dosing rate of the additive compound is proportional to the reference value of the additive concentration in the reactor and the fourth setpoint for the carbon oxide feed rate. The alkali-regulating compound may include ammonia and / or sodium hydroxide, e.g., consist of the following.

[0142] In particular, the setpoint for the carbon dioxide feed rate is the setpoint for the carbon dioxide feed rate during a first control iteration. The first setpoint for the dosage of the additive compound is, in particular, the setpoint. Qadsp(t2) the dosage of the additive compound during a second control iteration, where the first control iteration precedes the second control iteration.

[0143] In this embodiment, the chemical dosing of the additive compound enables the maintenance of a substantially constant concentration of this compound in the first culture medium. The chemical dosing is controlled based on the setpoint of the carbon oxide feed rate during the first control iteration, which is proportional to the water outflow during the first control iteration. This allows the culture medium to respond better to changes in conditions, and the process performance is more robust against these changes. According to the present invention, the additive compound is dosed according to the expected leaching of the compound, thereby reducing the delay in the dosing effect when compensating for the leaching.If the estimated process scale is smaller than the requested scale, dosing based on expected compound leaching may lead to a temporary increase in the concentration of the additive compound that supports the reaction. This temporary increase results in an increase in the process scale, thereby reducing the difference between the actual and desired process scale.

[0144] In particular, the first target value of the dosing rate of the additional compound is given by: Qadsp(t2)=κ×nad×Qcsp(t1).

[0145] Specifically, the coefficient κ is the ratio of water to methane produced in the methanation reaction, expressed in kg H₂O / mol carbon monoxide. In particular, in the case of the methanation of carbon dioxide, the coefficient κ is 0.036 kg H₂O / mol CO₂. In the case of the methanation of carbon monoxide, the coefficient κ is 0.018 kg H₂O / mol CO.

[0146] Furthermore, the initial target value for the dosage rate of the additional compound can be given by: Qadsp(t2)=μ×κ×nad×Qcsp(t1).

[0147] The coefficient µ is, in particular, a correction factor introduced to account for the amount of water that evaporates and thus prevents dilution of the additive compound. The actual value of the coefficient can be calculated using conventional methods, taking into account the water saturation in the reactor airspace. For example, during biomethanization at a temperature of approximately 60 °C and a pressure of approximately 10 bar-g, the coefficient µ can range between 0.9865 and 0.9885, specifically between 0.9870 and 0.9880, and most notably be equal to 0.9875.

[0148] For example, the first setpoint of the supply current of the auxiliary connection is calculated at least using Eq. (25) or Eq. (26).

[0149] A third aspect of the present invention relates to a method for iteratively controlling the dosage rate of an alkalinity-regulating compound additive in a methanation process in a reactor. According to this aspect, the methanation process is carried out in a second culture medium in the reactor and produces a product gas using a feed gas. In particular, the first culture medium consists of water and the alkali-regulating compound, and the feed gas consists of dihydrogen and carbon dioxide. The method according to the third aspect of the present invention comprises at least the following steps: - Initiating the calculation of a first target value of the dosage rate of the alkalinity-regulating compound, wherein the calculation of the first target value of the dosage rate of the alkalinity-regulating compound is carried out using a first requested value of the supply flow of carbon oxide, such that the first target value of the dosage rate of the alkalinity-regulating compound is suitable to compensate for the acidification of the second culture medium; and - Initiating the change in the supply flow of the alkalinity-regulating compound additive according to the first setpoint of the dosage rate of the alkalinity-regulating compound.

[0150] The first setpoint for the dosage rate of the alkali-regulating compound is proportional to the first requested value of the carbon oxide supply flow.

[0151] The first requested value of the carbon oxide supply flow is, in particular, the requested value. Qcreq(t2) of the carbon dioxide feed rate during a second control iteration. The first requested value of the carbon dioxide feed rate can, for example, be requested and / or used by a reactor operator. In particular, the first setpoint for the dosing rate of the alkalinity-regulating compound is the setpoint. Qalsp(t2) the dosage rate of the alkalinity-regulating compound during the second control iteration.

[0152] The alkalinity-regulating compound can be a strong and / or a weak base. In particular, the alkalinity-regulating compound can include ammonia and / or a phosphate, e.g., consist of ammonia and / or a phosphate group.

[0153] The first target value for the dosage rate of the alkali-regulating compound can be given by: Qalsp(t2)=η×Qcreq(t2).

[0154] In particular, the coefficient η is a factor that causes the steady-state concentration of the alkalinity-regulating compound to increase with the carbon dioxide flow, thereby reducing the change in pH of the second culture medium. For example, if the alkalinity-regulating compound is NH3 during the methanation of carbon dioxide, the coefficient η is equal to 0.008 mol-NH3 / mol-CO2. For example, the calculation of the first setpoint of the dosage rate of the alkalinity-regulating compound is carried out at least by using Eq. (27).

[0155] In methanization processes, an alkalinity-regulating compound can be added to the second culture medium to compensate for the acidification caused by the dissolution of acidic reactive gases, such as carbon dioxide, in this medium. The feed rate of the alkalinity-regulating compound is controlled by setting an initial desired value for the carbon dioxide feed rate, allowing for a relatively rapid increase in the concentration of the alkalinity-regulating compound and thus quickly counteracting the acidification of the second culture medium.

[0156] According to the present invention, the step of initiating a change in the dosing rate of a compound as a function of a setpoint for the dosing rate can include sending the setpoint to a computing device of the reactor and / or the power plant. In particular, the computing device controls a valve of the reactor or the power plant, wherein the valve regulates the dosing rate of the compound in the reactor. This step can be achieved, in particular, by changing the dosing rate of the compound as a function of the setpoint for the dosing rate of the compound.

[0157] The step of initiating a change in the dispensing rate of a connection according to a setpoint dispensing rate can include instructing a computing device to change the rate. For example, the computing device instructed to change the dispensing rate of a connection may be located in different locations.

[0158] For example, changing the compound's dosing rate according to the initial setpoint can involve controlling a valve in the reactor or power plant, with the valve regulating the compound's dosing rate into the reactor. The valve can, for instance, be controlled to regulate the compound's dosing rate according to the compound's setpoint.

[0159] According to the invention, the calculation of a quantity (e.g., a setpoint for the feed current of a reactant, an estimated value of the extent of the methanation process, a requested, setpoint, or estimated value of the feed current ratio, and / or a setpoint for the dosing rate of a compound) can be triggered by calculating the value of the quantity. Alternatively, or in conjunction with the foregoing, the calculation of the value of the quantity can be performed by instructing a computing unit of the reactor and / or the power plant to calculate the value of the quantity. For example, the calculation of the quantity's value is triggered by providing the computing unit with at least one measured physical quantity from the first set of measured physical quantities and / or one measured physical quantity from the first set of measured physical quantities.Alternatively or in conjunction with the foregoing, the calculation of the quantity value can be triggered by providing the computing device with the first measured value of the feed flow rate of the second reactant, the first reference value of the feed flow rate of the second reactant, the first requested value of the feed ratio, the requested value of the extent of the methanation process, the second requested value of the feed flow ratio, the value of the concentration of the additive compound in the first culture medium, the reference value of the molar mass of water in the first culture medium, and / or the first requested value of the feed flow rate of carbon dioxide. For example, the computing device tasked with calculating a quantity value and the computing device performing a method according to the present invention may be located at different locations.

[0160] It should be noted that each of the various features can be included or combined in any of the above-mentioned aspects of the invention, as is suitable and desired, in each of these aspects.

[0161] In particular, the second aspect of the present invention can be combined with the first aspect of the invention. For example, the method of the second aspect of the invention can comprise one or more steps of the method according to the first aspect of the present invention. In this case, if the second reactant is carbon oxide, the setpoint for the carbon oxide feed rate of the second aspect of the invention can be the first setpoint for the feed rate of the second reactant. If the first reactant is carbon oxide, the setpoint for the carbon oxide feed rate according to the second aspect of the invention can be the setpoint for the feed rate of the first reactant during the first control iteration. The method according to the second aspect of the invention can, for example, include the step of initiating the calculation of the setpoint for the first reactant.

[0162] The third aspect of the present invention can be combined with the second aspect of the invention. In particular, the method according to the third aspect of the present invention can comprise one or more steps of the method according to the second aspect of the present invention, and / or the method according to the second aspect of the invention can comprise one or more steps of the method according to the third aspect of the present invention. In particular, the second culture medium can be the same as the first culture medium, i.e., the second culture medium can contain the additive compound.

[0163] The third aspect of the present invention can also be combined with the first aspect of the invention. In particular, the method according to the third aspect of the present invention can comprise one or more steps of the method according to the first aspect of the present invention. In this case, if the second reactant is carbon oxide, the first required value of the carbon oxide feed stream according to the third aspect of the invention can be the first required value of the second reactant feed stream according to the first aspect of the invention.

[0164] The present invention also relates to a data processing system comprising a processing unit configured to perform the method according to the first aspect of the present invention, the method according to the second aspect of the present invention, and / or the method according to the third aspect of the present invention. Furthermore, the present invention also relates to a reactor arrangement for carrying out a methanization process, which includes the data processing system of the present invention. In particular, the reactor arrangement may include measuring means for measuring at least one physical quantity from the first set of physical quantities.

[0165] The present invention relates to a computer program product comprising instructions which, when the program is executed by a data processing system, cause the system to execute the method according to the first aspect of the present invention, the method according to the second aspect of the present invention, and / or the method according to the third aspect of the present invention. In particular, the computer program product comprises instructions which, when the program is executed by the reactor arrangement according to the invention, cause it to execute at least one of the methods of the present invention.

[0166] Furthermore, the present invention relates to a computer-readable storage medium containing instructions which, when executed by a data processing system, cause the system to execute the method according to the first aspect of the present invention, the method according to the second aspect of the present invention and / or the method according to the third aspect of the present invention.

[0167] In particular, the computer-readable storage medium comprises instructions which, when executed by the reactor arrangement according to the invention, cause the arrangement to carry out at least one of the methods of the present invention.

[0168] Exemplary embodiments of the invention are described below with reference to the accompanying figures. The figures and the associated detailed description serve only to improve understanding of the invention and do not constitute any limitation of the scope of the invention as defined in the claims. In particular, they show: Fig. 1 a schematic representation of an embodiment of the reactor arrangement according to the present invention; Fig. 2 a flowchart of the process of a first embodiment of the method according to the first aspect of the present invention; Fig. 3 a flowchart of the process of a second embodiment of the method according to the first aspect of the present invention; Fig. 4 a flowchart of the process of a first embodiment of the method according to the second aspect of the present invention; Fig. 5a the time dependence of the requested and the measured feed ratio in a first simulation of the methanization of carbon dioxide; Fig. 5b, Fig. 5c the temporal dependence of the amount of methane and dihydrogen in the product gas compared to the product gas of the first simulation; Fig. 6a the temporal dependence of the target value of the carbon dioxide feed flow in a first simulation of the methanization of carbon dioxide; Fig. 6b the time dependence of the amount of methane, dihydrogen and carbon dioxide in the product gas compared to the product gas of the second simulation and Fig. 6c the time dependence of the requested and the measured supply ratio of a second simulation of the methanization of carbon dioxide.

[0169] Fig. Figure 1 is a schematic representation of an embodiment of the reactor arrangement 100 according to the present invention.

[0170] The reactor arrangement 100 comprises a carbon dioxide supply 114, a dihydrogen supply 124, a gas supply 164, a reactor 160, and a product gas line 144. The carbon dioxide supply 114 connects the gas supply 164 to a carbon dioxide source 110. The carbon dioxide source 110 can be a tank for storing a first feed gas or a biogas reactor that produces this feed gas. The first feed gas consists of carbon dioxide and may also contain methane.

[0171] The dihydrogen supply 124 connects the gas supply 164 to a dihydrogen source 120. The dihydrogen source 120 can be a tank for storing a second feed gas or a reactor that produces the second feed gas, dihydrogen, e.g., from H₂O, through a suitable electrolysis reaction. The second feed gas consists, in particular, of dihydrogen and one or more impurities.

[0172] The gas supply 164 connects the carbon dioxide source 110 and the dihydrogen source 120 to the reactor 160, which in turn is connected to the product gas line 144. The reactor 160 is configured to contain an aqueous culture medium containing suitable methanogenic microorganisms, e.g., archaea, for converting the feed gas into the product gas. The product gas line 144 connects the reactor 160 fluidically to a tank 140 for storing the product gas and / or to a grid (not shown) for distributing the product gas.

[0173] During operation, the first feed gas is fed from carbon dioxide source 110 via carbon dioxide feed 114 and gas feed 164 into reactor 160. The second feed gas is fed from dihydrogen source 120 via dihydrogen feed 124 and gas feed 164 into reactor 160. During operation, reactor 160 contains the aqueous culture medium in which carbon dioxide and dihydrogen are dissolved. The methanogenic microorganisms carry out the methanation process using carbon dioxide and dihydrogen. The product gas generated in the reactor is fed via product gas line 144 into tank 140 and / or into the distribution network.

[0174] The reactor arrangement 100 comprises a first valve 112 and a second valve 122. The first valve 112 is connected to the carbon oxide feed 114 and configured to regulate the feed rate of the second feed gas flowing through the carbon oxide feed 114 during operation. The feed rate of the first feed gas is regulated according to a setpoint, e.g., such that the nominal flow rate of the first feed gas flowing through the carbon oxide feed 114 is substantially equal to the setpoint. The second valve 122 is connected to the dihydrogen feed 124 and configured to regulate the dihydrogen flow rate flowing through the dihydrogen feed 124 during operation. The feed rate of the second feed gas is regulated according to a setpoint, e.g.,such that the setpoint of the flow rate of the second feed gas through the dihydrogen supply 124 is essentially equal to the setpoint of the supply flow rate of the second feed gas. The first valve 112 and / or the second valve 122 can be intelligent devices with their own CPU and / or memory.

[0175] The reactor assembly 100 includes a first flow meter 113 connected to the carbon dioxide feed 114. The first flow meter 113 is configured to measure the feed rate, e.g., the volumetric feed rate, of the first feed gas flowing through the carbon dioxide feed 114 during operation. The reactor assembly 100 may further include a second flow meter 123, which may be connected to the dihydrogen feed 124. If present, the second flow meter 123 may be configured to measure the feed rate, e.g., the volumetric feed rate, of the second feed gas flowing through the dihydrogen feed 124 during operation. The first flow meter 113 and / or the second flow meter 123 may be, for example, a vortex-shedding flow meter and / or intelligent devices with their own CPU and memory.

[0176] The reactor arrangement includes a first gas analyzer 111 connected to the carbon dioxide feed 114. The first gas analyzer 111 is configured to analyze the composition of the first feed gas flowing through the carbon dioxide feed 114 during operation. In particular, the first gas analyzer 111 is configured to determine the amount of carbon dioxide in the first feed gas relative to the first feed gas, xC,F1mea, and the amount of methane in the first feed gas in relation to the first feed gas, xM,F1mea, The reactor arrangement further comprises a second gas analyzer 141, which is connected to the product gas line 144. The second gas analyzer 141 is configured to analyze the composition of the product gas flowing through the product gas line 141 during operation. In particular, the second gas analyzer 141 is configured to measure the amount of carbon oxide in the product gas relative to the product gas, xC,F1mea, the amount of methane in the product gas in relation to the product gas, xM,F1mea, and the amount of dihydrogen in the product gas relative to the product gas, xH,Pmea, measures. The first gas analyzer 111 and / or the second gas analyzer 141 are, for example, infrared gas detectors and / or intelligent devices with their own CPU and / or memory.

[0177] The reactor arrangement comprises a data processing system (DPS) 150, which may consist of a computing device or a cluster thereof. The data processing system 150 comprises a processing element 158 ​​and storage means 159, which are in data communication with each other. The processing element 158 ​​may consist of or comprise a CPU and / or a GPU and comprises several modules configured to perform the steps of the method of the present invention.

[0178] The memory device 159 can comprise volatile primary memory (e.g., RAM, DRAM, SRAM, CPU cache memory, or the like) and / or non-volatile primary memory (e.g., ROM, PROM, EPROM, or the like). The memory device 159 can further comprise secondary memory. The secondary memory can store a computer program product containing instructions which, when executed by the DPS 150, cause the DPS 150 to execute the method according to the present invention.

[0179] The DPS includes an input / output (I / O) interface (not shown) that allows the DPS 150 to communicate with input / output devices, e.g., devices configured to provide the DPS 150 with a requested value of the feed ratio and / or a requested value of the feed current of the second reactant.

[0180] The processing element 158 ​​comprises a first module (not shown) configured to instruct the first valve 112 to regulate the supply flow of the first feed gas according to a setpoint. The instructions from the DPS 150 are sent to the first valve 112 via an electrical, optical, and / or wireless connection 151 between the DPS 150 and the first valve 112. The processing element 158 ​​comprises a second module (not shown) configured to instruct the second valve 122 to regulate the supply flow of the second feed gas according to a setpoint. The instructions from the DPS 150 are sent to the second valve 122 via an electrical, optical, and / or wireless connection 152 between the DPS 150 and the second valve 122.

[0181] The processing element 158 ​​includes a third module (not shown) configured to instruct the first gas analyzer 111 to measure the concentration of carbon dioxide and methane in the first feed gas. The instructions from the DPS 150 are sent to the first gas analyzer 111 via an electrical, optical, and / or wireless link 153. In response to the instructions from the DPS 150, the first gas analyzer 111 performs the measurement and sends the result of the measurement to the DPS 150 via the link 153. The third module is configured to access the result of the measurement sent by the first gas analyzer 111. The processing element 158 ​​includes a fourth module (not shown) configured to instruct the second gas analyzer 141 to measure the concentration of carbon dioxide, dihydrogen, and methane in the product gas.The instructions from the DPS 150 are sent to the second gas analyzer 141 via an electrical, optical, and / or wireless connection 155. In response to the instructions from the DPS 150, the second gas analyzer 141 performs the measurement and sends the result of the measurement back to the DPS 150 via the connection 155. The fourth module is further configured to access the result of the measurement sent by the second gas analyzer 141.

[0182] The processing element 158 ​​includes a fifth module (not shown) configured to instruct the first flow meter 113 to measure the supply flow rate of the first feed gas. The instructions from the DPS 150 are sent to the first flow meter 113 via an electrical, optical, and / or wireless connection 155. In response to the instructions from the DPS 150, the first flow meter 113 performs the measurement and sends the result of the measurement to the DPS 150 via the connection 155. The fifth module is configured to access the result of the measurement sent by the first flow meter 113. The processing element 158 ​​includes a sixth module (not shown) configured to instruct the second flow meter 123 to measure the supply flow rate of the second feed gas. The instructions from the DPS 150 are sent to the second flow meter 113 via an electrical, optical, and / or wireless connection 156.In response to the instructions from the DPS 150, the second flow meter 123 performs the measurement and sends the result to the DPS 150 via connection 156. The sixth module is configured to access the result of the measurement sent by the second flow meter 123.

[0183] The reactor arrangement can include a feed for the additive compound 134 and a third valve 132. The feed 134 for the additive connects the reactor 160 to a tank 130, which serves to store the additive. The additive compound can be in liquid form and contain water and ammonia, with the ammonia dissolved in water. During operation, the additive compound is fed from the tank 130 into the reactor 160 via the additive feed 134 and mixed with the aqueous culture medium to maintain favorable conditions for methanation in the reactor.

[0184] The reactor arrangement can include a third valve 132, which is connected to the feed of the additive compound 134 and configured to control the dosing rate of the additive compound flowing through the feed of the additive compound 134 during operation. The dosing rate is controlled based on a setpoint value, such that the dosing rate of the additive compound flowing through the additive feed 134 is essentially equal to the setpoint value. The third valve 132 can be an intelligent device with its own CPU and / or memory. The processing element 158 ​​can include a seventh module (not shown) configured to instruct the third valve 132 to regulate the dosing rate of the additive compound according to a setpoint value. The instructions from the DPS 150 are sent to the third valve 132 via an electrical, optical, and / or wireless connection 157.

[0185] Fig. Figure 2 is a flowchart of the operation of a first embodiment of the first aspect of the present invention. In this embodiment, the first reactant is dihydrogen, e.g., carbon oxide is the leading reactant. In particular, this embodiment can be achieved by the above-described and in Fig. 1. A schematically represented reactor arrangement 100 is carried out. The first embodiment of the first aspect of the present invention comprises a plurality of control iterations.

[0186] In step 205, the DPS 150 accesses the requested value b. req (t1) of the input ratio at the first tax iteration and the requested value QCreq(t1) of the carbon oxide feed stream during the first control iteration to . The values ​​b req (t1) and QCreq(t1) are provided to the DPS 150, in particular by a user via an input device connected to the I / O interface of the DPS 150. In particular, b req (t1) = 4.02 and QCreq(t1)=22 Nm3 / h.

[0187] In step 210, the supply flow of the first feed gas is adjusted according to the requested value. QCreq(t1) and the second feed gas is adjusted according to the target value, QHsp(t1)=breq(t1)×QCreq(t1). In particular, the DPS 150 instructs the second valve 122 to adjust the supply flow of the second feed gas according to the setpoint. QHsp(t1) to regulate. In addition, the DPS 150 instructs the first valve 112 to regulate the supply flow of the first conveying gas according to the requested value. QCreq(t1) to regulate.

[0188] The general control iteration of the multiple control iterations of this embodiment is described in the form of a counter m, which is initialized to zero in step 255. As mentioned above, the m-th control iteration is assigned to the respective time interval m. th assigned a time interval, where the m-th time interval is the time t m The m-th time interval is disjoint from and follows the (m-1)th time interval and includes time t. m . In particular, for each m the difference (t m - t m-1 ) equals 15 s. In the following, the quantities relating to the m-th control iteration can be considered as from time t. m A measured value that is described as dependent on t m This is specifically a value that is measured at the m-th control iteration, but not necessarily at time t. m .

[0189] In step 215 of the m-th control iteration, the measured value is QF1mea(tm) The supply flow rate of the first feed gas is measured. In particular, the DPS 150 instructs the first flow meter 113 to measure the following: QF1mea(tm). In response to the DPS instruction, the first flow meter 113 performs the measurement and sends the measured value. QF1mea(tm) to the DPS 150, receives this value, accesses it and stores it in memory facility 159.

[0190] In step 220 of the m-th control iteration, the following are measured: the measured value xC,Pmea(tm) the amount of carbon oxide in the product gas, relative to the product gas, the measured value xM,Pmea(tm) the amount of methane in the product gas, relative to the product gas, and the measured value xH,Pmea(tm) the amount of dihydrogen in the product gas, relative to the product gas. In particular, the DPS 150 instructs the second gas analyzer 141 to measure the following: xC,Pmea(tm),xM,Pmea(tm) and xH,Pmea(tm) In response to the instruction from the DPS 150, the second gas analyzer 141 performs the measurements and sends the measured values. xC,Pmea(tm),xM,Pmea(tm) and xH,Pmea(tm) to the DPS 150. The DPS 150 receives these values, accesses them and stores them in memory device 159.

[0191] In step 225 of the m-th control iteration, the following are measured: the measured value xC,F1mea(tm) the amount of carbon oxide in the first feed gas, relative to the first feed gas, and the measured value xM,F1mea(tm) the amount of methane in the first feed gas, relative to the first feed gas. In particular, the DPS 150 instructs the first gas analyzer 111 to measure the following: xC,F1mea(tm) and xM,F1mea(tm). In response to the instruction from the DPS 150, the first gas analyzer 111 performs the measurements and sends the measured values. xC,F1mea(tm) and xM,F1mea(tm) to the DPS 150. The DPS 150 receives these values, accesses them and stores them in memory unit 159.

[0192] In step 230 of the m-th control iteration, the DPS 150 accesses the requested value b. req (t m+1 ) of the supply ratio at the (m + 1)th control iteration and the requested value QCreq(tm+1) of the carbon oxide feed stream at the (m + 1)th control iteration (step 230). The values ​​b req (t m+1 ) and QCreq(tm+1) The values ​​are provided to the DPS 150, in particular by a user via an input device connected to the I / O interface of the DPS 150. req (t m+1 ) and QCreq(tm+1) can be accessed via a fourth or fifth function. In particular, b req (t m+1 ) equal to the value of the fourth function at t m+1 , and QCreq(tm+1) is equal to the value of the fifth function at t m+1 The representation of the fourth function can, for example, be the dashed line from Fig. 5a, and / or the representation of the fifth function can be the dashed line from Fig. 6a.

[0193] In step 235 of the m-th control iteration, the DPS 150 calculates the setpoint. QHsp(tm+1) of the dihydrogen supply flow during the (m + 1)th control iteration. This step includes the calculation of the estimated value b. est (t m ) of the feed ratio during the m-th control iteration using Eq. (23) with the substitutions t1 → t m The DPS 150 also calculates the value f. b,m the first function at the m-th iteration, fb,m=best(tm) / breq(tm)−1. b req (t m ) is the requested value of the feed ratio in the m-th iteration, which is accessed by the DPS 150 in step 230 of the (m - 1)th control iteration.

[0194] Step 235 involves calculating an estimated value D b,m the time derivative of the first function at the m-th control iteration and an estimated value I b,m of the time integral of the first function during the m-th control iteration according to the following formulas: Db,m=fb,m−fb,m−1tm−tm−1,Ib,m=∑j=mm−1[fb,j+1×(tj+1−tj)].

[0195] f b,j is the value of the first function at a j-th control iteration (j = m - N) m , m - N m + 1, ..., m). The j-th control iteration is assigned to a corresponding j-th time interval. The j-th time interval is disjoint from and follows the (j + 1)th time interval and includes time t. jIn particular, for each j = m - N m ,m - N m + 1, ..., m the difference (t j+1 - t j ) equals 15 s. The integer N m is given by N m = min(N0, m). The number N0 can be chosen such that (t m+N0 - t N0 ) between 1 min and 6 min, and especially between 3 min and 5 min. For example, N0 can be equal to 20.

[0196] The DPS 150 calculates the target value b sp (t m+1 ) of the supply flow ratio at the (m + 1)th control iteration, e.g.(tm+1)=breq(tm+1)1+(c1×fb,m+c2×Db,m+c3×Ib,m).

[0197] For example, c1 = 0.5, c2 = 0.5 min and c3 = 2.5 min -1 . b sp (t m+1 ) is used to calculate the target value QHsp(tm+1) of the dihydrogen supply flow during the (m + 1)th control iteration using Eq. (4) with the substitutions t1 → t m and t2 → t m+1 The second value QC(2)(tm+1) The supply flow of carbon oxide at the (m + 1)th control iteration is given by QC(2)(tm)=QCreq(tm+1).

[0198] In step 240, the supply flow of the second feed gas is adjusted according to the setpoint. QHsp(tm+1) amended. In particular, the DPS 150 instructs the second valve 122 to adjust the supply flow of the second feed gas according to the setpoint. QHsp(tm+1) to regulate. In step 245, the supply flow of the first feed gas is adjusted according to the requested value of carbon dioxide. QCreq(tm+1) changed. In particular, the DPS 150 calculates the target value. QF1sp(tm+1) of the first feed gas, which is provided by QF1sp(tm+1)=QCreq(tm+1) / xC,F1mea(tm) The DPS 150 instructs the first valve 112 to control the supply flow of the first feed gas according to the setpoint. QF1sp(tm+1) to regulate.

[0199] In step 250 of the m-th iteration, the DPS 150 checks whether the iterative control of the methanization process should be terminated or continued. The iterative control of the methanization process might end, for example, because the reactor assembly is shut down, e.g., for maintenance. If the iterative control of the methanization process is to be continued, the DPS 150 increments the counter value by one (see step 260) and executes the (m + 1)th control iteration.

[0200] Further embodiments of the method according to the first aspect of the invention may include steps 205 to 260 described above. In particular, these embodiments differ from the first embodiment of the first aspect of the invention in the order in which steps 215 to 230 are performed. Specifically, in a further embodiment, steps 220, 225, and / or 230 may be performed in any order before step 215. Alternatively, or in combination with the foregoing, steps 215, 220, and / or 225 may be performed in any order after step 230 and before step 235. In some embodiments, step 245 may be performed before steps 240 and / or 235 and after step 230.

[0201] Fig. Figure 3 is a flowchart 200 of the process of a second embodiment of the method of the present invention. In this embodiment, the first reactant is dihydrogen, e.g., carbon oxide is the leading reactant. In particular, this embodiment can be achieved by the above-described and in Fig. 1 schematically represented reactor arrangement 100 will be carried out.

[0202] The second embodiment comprises a plurality of control iterations. The generic control iteration of the plurality of control iterations in this embodiment is described in the form of a counter m, which is initialized to zero in step 255. As mentioned above, the m-th control iteration is associated with the respective m-th time interval, where the m-th time interval is time t. m The m-th time interval is disjoint from and follows the (m - 1)th time interval and includes time t. m. In particular, for each m the difference (t m - t m-1 ) equals 15 s. In the following, the quantities relating to the m-th control iteration can be considered as from time t. m A measured value that is described as dependent on t m The term denoted is, in particular, a value measured at the m-th control iteration, although not necessarily at time t. m .

[0203] In step 205, the DPS 150 accesses: the requested value b req (t1) of the input ratio at the first tax iteration, the requested value QCreq(t1) of the carbon oxide feed stream during the first control iteration and the reference value QCref(t1) of the carbon dioxide supply flow at the first control iteration and the requested value y req (t1) of the extent of the methanization process. The values breq(t1),QCref(t1),yreq(t1)and QCreq(t1) The DPS 150 is provided, in particular, by a user via an input device connected to the DPS 150's I / O interface. Specifically, breq(t1)=4.02, QCreq(t1)=22 Nm3 / h,QCref(t1)=19 Nm3 / h and yreq(t1)=0.993.

[0204] Steps 210, 215, 220 and 225 of the second embodiment are identical to steps 210, 215, 220 and 225 of the first second embodiment, as described above and in Fig. 2 schematically represented.

[0205] In step 310 of the m-th control iteration, the DPS 150 accesses the requested value y. req (t m+1 ) the extent of the methanization process at the (m + 1)th control iteration and to the requested value QCreq(tm+1) of the carbon oxide feed stream during the (m + 1)th control iteration. The values ​​y req (t m+1 ) and QCreq(tm+1) The values ​​are provided to the DPS 150, in particular by a user via an input device connected to the DPS 150's I / O interface. req (t m+1 ) and QCreq(tm+1) can be retrieved via a sixth or seventh function. In particular, y req (t m+1 ) equal to the value of the sixth function at t m+1, and QCreq(tm+1) is equal to the value of the seventh function at t m+1 The representation of the seventh function can be, for example, the dashed line of Fig. 6a. The sixth function can be a constant function equal to y. req (t1) is.

[0206] In step 320 of the m-th control iteration, the DPS 150 calculates the setpoint. QCsp(tm+1) of the carbon dioxide feed-in flow during the (m + 1)th control iteration. Step 320 involves calculating an estimated value D. y,mthe time derivative of the second function in the m-th control iteration and an estimated value I y,m of the time integral of the second function during the m-th control iteration. The estimated values ​​D y,m and I y,m are obtained using Eq. (29) with the substitutions D b,m → D y,m , I b,m → I y,m and f b ,... → f y ... calculated. The value f y,j is the value of the second function at a j-th control iteration (j = m - N) m , m - N m + 1, ..., m).

[0207] In step 320, the DPS 150 calculates the reference value. QCref(tm+1) of the carbon oxide supply flow at the (m + 1)th control iteration as follows: QCref(tm+1)=QCref(tm)×β×(fy,m+c^5×Dy,m+c^6×Iy,m)β=c4+×Θ0(fy,m)+c4−×Θ0(−fy,m). QCref(tm) is the reference value of the carbon oxide feed rate at the m-th control iteration, as calculated during the (m - 1)th control iteration. For example, c4+=0.002,c4−=0.1, c^5=1 min and c^6=0.1 min−1.

[0208] The target value QCsp(tm+1) The supply flow rate of carbon oxide at the (m + 1)th control iteration is calculated using the following equation: QCsp(tm+1)=min(QCref(tm+1),QCreq(tm+1)).

[0209] In step 330 of the m-th control iteration, the DPS 150 calculates the setpoint. QHsp(tm+1) of the dihydrogen supply flow at the (m + 1)th control iteration. The DPS 150 calculates the estimated value b. est (t m ) of the supply ratio at the m-th tax iteration and the value f b,m the first function at the m-th iteration. The values ​​b est (t m ) and f b,mare calculated as in step 235 of the first embodiment of the first aspect of the present invention, as described above and schematically in Fig. 2 is shown. Furthermore, step 330 includes calculating an estimated value D. b,m the time derivative of the first function at the m-th control iteration and an estimated value I b,m of the time integral of the first function in the m-th control iteration using the formulas from Eq. (29).

[0210] The DPS 150 calculates the estimated value y est (t m ) for the extent of the methanization process at the m-th control iteration using Eq. (24) with the substitutions t1 → t m The DPS 150 also calculates the value f. y,m The second function is determined in the m-th iteration using Eq. (28) with the substitution b → y. The value y req (t m) is the requested value of the feed ratio at the m-th iteration, accessed by the DPS 150 in step 310 of the (m - 1)th control iteration. Step 330 involves calculating the value g. y,m the third function at the m-th iteration, gy,m=gy(yest(tm)−yreq(tm),yreq(tm)),

[0211] with regard to the function g y defined in Eq. (18) and the function f y from Eq. (14).

[0212] Step 330 involves calculating an estimate of the time derivative of the third function at the m-th control iteration and an estimate Î y,m of the time integral of the third function during the m-th control iteration. The estimated values ​​and Î y,m are obtained using Eq. (29) with the substitutions D b,m → D̂ y,m , I b,m → Î y,m and f b ,... → g y ... calculated. The value g y,jis the value of the third function at the j-th control iteration (j = m - N) m , m - N m + 1,...,m).

[0213] In step 330, the DPS calculates the requested value b. req (t m+1 ) of the supply ratio at (m + 1) th Iteration with respect to the requested value b req (t m+1 ) of the supply ratio at the m-th control iteration: α=breq(tm+1)=breq(tm)×[1+α×λ^],[breq(tm)−bminbreq(tm)×Θ0(λ^)+bmax−breq(tm)breq(tm)×Θ1(−λ^)],λ^=(c7×gy,m+c8×D^y,m+c9×I^y,m).

[0214] For example, c7 = -500, c8 = -50 min and c9 = -500 min -1 Step 330 involves calculating the target value b. sp (t m+1 ) of the supply ratio at the (m + 1)th control iteration with respect to the requested value b req (t m+1 ) from Eq. (33) using Eq. (30). The target value b sp (t m+1 ) is used to calculate the target value, QHsp(tm+1) of the dihydrogen supply flow during the (m + 1)th control iteration using Eq. (4) with the substitutions t1 → t m and t2 → t m+1 The second value QC(2)(tm+1) of the carbon oxide feed stream at the (m + 1)th control iteration. Control iteration is given by QC(2)(tm+1)=QCsp(tm+1).

[0215] Step 240 is identical to step 240 of the first embodiment of the first aspect of the present invention, as described above and schematically shown in Figure 1. Fig. Figure 2 is shown. In step 245, the supply flow of the first feed gas is adjusted according to the target value of the carbon dioxide. QCsp(tm+1) changed. In particular, the DPS 150 calculates the target value. QF1sp(tm+1) of the first feed gas, which is provided by QF1sp(tm+1)=QCsp(tm+1) / xC,F1mea(tm). Furthermore, the DPS 150 instructs the first valve 112 to adjust the supply flow of the first feed gas according to the setpoint. QF1sp(tm+1) to regulate. Step 250 is identical to step 250 of the first embodiment of the first aspect of the present invention, as described above and schematically shown in Fig. 2 shown. In particular, if the iterative control of the methanization process is to be continued, the DPS 150 increments the value of the counter by one, see step 260, and executes the (m + 1)th control iteration.

[0216] Further embodiments of the method according to the first aspect of the invention may include steps 205 to 225, 310 to 330, and 240 to 260 described above. In particular, these embodiments differ from the second embodiment of the first aspect of the invention in the order in which steps 215 to 225 and 310 are performed. Specifically, in a further embodiment, steps 220, 225, and / or 310 may be performed in any order before step 215. Alternatively, or in conjunction with the foregoing, steps 215, 220, and / or 225 may be performed in any order after step 310 and before step 320. In some embodiments, step 245 may be performed before steps 240 and / or 330 and after step 320.

[0217] Fig. Figure 4 is a flowchart 400 for the operation of a first embodiment of the second aspect of the present invention. In particular, this embodiment can be achieved by the above-described and in Fig. 1. A schematically represented reactor arrangement is used. The first embodiment of the third aspect of the present invention comprises a plurality of control iterations. The generic control iteration of the plurality of control iterations of this embodiment is described in the form of a counter m, which is initialized to the value zero in step 405. As mentioned above, the m-th control iteration is assigned to the respective m-th time interval, wherein the m-th time interval is the time t. m The m-th time interval is disjoint from and follows the (m - 1)th time interval and includes time t. m . In particular, for each m the difference (t m - t m-1) equals 15 s. In the following, the quantities relating to the m-th control iteration can be considered as from time t. m can be described as dependent. A is described as dependent on t. m The designated measured value is, in particular, a value that is measured during the m-th control iteration, although not necessarily at time t. m .

[0218] In step 415 of the m-th control iteration, the DPS 150 accesses the setpoint. QCsp(tm) of the carbon oxide supply flow during the m-th control iteration. In particular, the value QCsp(tm) The setpoint is stored in memory unit 159 of the DPS 150 and retrieved by processing element 158. For example, the setpoint can be... QCsp(tm) The setpoint is provided by a user to the DPS 150 via an input device connected to the DPS 150's I / O interface. QCsp(tm) This can be a setpoint calculated in step 320 of the (m-1)th control iteration of the second embodiment of the first aspect of the invention. In particular, the m-th control iteration of the first embodiment of the second aspect of the present invention can comprise steps 215, 220, 225, 310, 320, 330, 240, and 245 of the second embodiment of the first aspect of the present invention. Furthermore, the first embodiment of the second aspect of the present invention can also comprise steps 215 and 210 of the second embodiment of the first aspect of the present invention.

[0219] In step 420 of the m-th control iteration, the DPS 150 calculates the setpoint. Qadsp(tm+1) The dosing rate of the additional compound during the (m + 1)th control iteration. The setpoint. Qadsp(tm+1) is done using Eq. (25) or Eq. (26) with the substitutions t1 → t m and t2 → t m+1calculated. In step 425 of the m-th control iteration, the dosing rate of the additional compound is calculated according to the setpoint. Qadsp(tm+1) changed. In particular, the DPS 150 instructs the third valve 132 to adjust the dosing rate of the auxiliary connection according to the setpoint. Qadsp(tm+1) to regulate.

[0220] In step 430 of the m-th iteration, the DPS 150 checks whether the iterative control of the additive dosing should be terminated or continued. The iterative control of the additive dosing might terminate, for example, because the reactor setup is shut down, e.g., for maintenance. If the iterative control of the additive dosing is to be continued, the DPS 150 increments the counter value by one (see step 410) and executes the (m + 1)th control iteration.

[0221] Fig. Figure 5a shows the time dependence of the requested feed ratio (dashed line) and the measured feed ratio (solid line) of a first simulation of the methanation of carbon dioxide in a reactor arrangement according to the present invention, e.g., in the one described above and in Fig. Figure 1 is schematically represented. In the first simulation, the measurements of the first gas analyzer 111, the second analyzer 141, the first flow meter 113, and the second flow meter 123 are affected by randomly generated noise. A negative distortion of -0.5% in the readings of the first flow meter 113 simulates an undetected change in the composition of the first feed gas. In the first simulation, the requested value of the carbon dioxide feed flow is constant and equal to QCreq=22 N m3 / h.

[0222] In a first time period 501, the methanization process is iteratively controlled using the first embodiment of the first aspect of the present invention, as described above and in Fig. 2 schematically represented. In a second time period 502, the method according to the first aspect of the present invention is not carried out instead.

[0223] In the second time period 502, the supply flow of the first and second gas supply is periodically adjusted at regularly recurring times τ1, τ2, ..., τ M stopped. At the generic time τ s The DPS 150 receives a requested value QC,sreq of the carbon dioxide supply flow and a requested value bsreq for the feed ratio. In response to receiving these values, the reactor arrangement measures the value xC,smea the amount of carbon dioxide in the first feed gas in relation to the first feed gas and calculates the target value QF1,ssp of the first feed gas, QF1,ssp=QC,sreq / xC,smea. The reactor arrangement regulates the supply flow of the first feed gas according to QF1,sreq and regulates the supply flow of the second feed gas after the product bsreq×QC,sreq.

[0224] The time dependence of the measured supply ratio b mea This is obtained by periodically estimating the ratio between the dihydrogen feed flow and the carbon dioxide feed flow, whereby this estimation is based on measuring the feed flow of the first feed gas, the feed flow of the second feed gas, and the amount of methane in the first feed gas relative to the first feed gas. xC,F1mea is carried out.

[0225] In the first time period 501, the iterative control of the first aspect of the present invention enables compensation of the distortion, such that the solid curve essentially overlaps with the dashed curve and oscillates around it. In the second time period, the distortion is not compensated and the measured feed ratio is systematically smaller than the requested ratio.

[0226] Fig. 5b and Fig. Figure 5c shows the time dependence 510 of the measured value. xM,Pmea the amount of methane in the product gas, relative to the product gas of the second simulation, and the time dependence 520 of the estimated value xH,Pmea the amount of dihydrogen in the product gas, relative to the product gas of the second simulation.

[0227] In the first time period 501, the in Fig. 5b and Fig. The time dependencies 510 and 520 shown in 5c were determined by plotting the measured values. xM,Pmea and xH,Pmea obtained, which were measured at step 220 of each control iteration of the first embodiment of the first aspect of the invention (see also Fig. 2) In the second time period 502, the time dependencies 510 and 520 are obtained by periodically measuring the amount of methane in the product gas relative to the product gas and the amount of dihydrogen in the product gas relative to the product gas using the second gas analyzer 141.

[0228] Fig. 5b and Fig. Figure 5c shows that the method according to the second aspect of the present invention improves the extent of the methanization process. In particular, as shown in Fig. 5b best shows, is for the same value of b req the value of xM,Pmea in the first time period 501 and thus the methanization capacity is higher than the value of xM,Pmea in the second time period 502. Furthermore, for the same value of b req the value of xH,Pmea in the first time period 501 smaller than the value of xH,Pmea in the second time period 502.

[0229] Fig. Figure 6a shows the time dependency (solid line) of the setpoint. QCsp of the carbon dioxide supply stream of a second simulation of the methanization of carbon dioxide in a reactor arrangement according to the present invention, e.g. in the one described above and in Fig. 1 schematically represented. In the second simulation, the methanization process is iteratively controlled by using the second embodiment of the first aspect of the present invention, as described above and in Fig. Figure 3 is shown schematically. The measurements of the first gas analyzer 111, the second analyzer 141, the first flow meter 113, and the second flow meter 123 are affected by randomly generated noise. A positive distortion of 0.2% in the readings of the first flow meter 113 simulates an undetected change in the composition of the first feed gas. In the second simulation, the requested value for the extent of the methanation process is constant and equal to y. req = 0.993.

[0230] Fig. Figure 6a also shows the time dependency (dashed line) of the requested value. QCreq and the time dependence (dashed line) of the reference value QCref of the carbon dioxide supply flow of the second simulation. The solid line and the dashed line are obtained by plotting the setpoint and reference values ​​of the carbon dioxide supply flow, which are calculated in step 220 of each control iteration of the second embodiment of the first aspect of the invention. The dashed line is obtained by plotting the requested values, which are accessed in step 310 of each control iteration of the second embodiment of the first aspect of the invention (see Figure 310). Fig. 3). The in Fig. The dashed line shown in 6a indicates the maximum value. QCmax of the carbon dioxide supply stream. QCmax=20 Nm3 / h is the maximum amount of carbon dioxide that can be converted into the product gas in the second simulation.

[0231] Fig. Figure 6b shows the time dependence 610 of the estimated value. xM, Plague the amount of methane in the product gas, relative to the product gas, the time dependence 620 of the estimated value xH, Plague the amount of dihydrogen in the product gas, relative to the product gas, and the time dependence 630 of the estimated value xC, Plague the amount of carbon dioxide in the product gas relative to the product gas of the second simulation. The in Fig. The time dependencies 610, 620 and 630 shown in 6b are obtained by plotting the measured values. xM,Pmea,xH,Pmea, and xC,Pmea, which were measured in step 220 of each control iteration of the second embodiment of the first aspect of the invention (see also Fig. 3).

[0232] Fig. Figure 6c shows the time dependency (dashed line) of the requested supply ratio b. req and the time dependence (solid line) of the measured supply ratio b meathe second simulation. The time dependence of the measured feed ratio is determined by periodically estimating the ratio between the dihydrogen feed flow and the carbon dioxide feed flow, whereby this estimation is based on measuring the feed flow of the first feed gas, the feed flow of the second feed gas, and the amount of methane in the first feed gas relative to the first feed gas. xC,F1mea, This is done. The time dependency (dashed line) of the requested supply ratio is determined by plotting the requested values ​​b. req determined in step 310 of each control iteration of the second embodiment 300 of the first aspect of the invention. Fig. 6c overlaps b mea essentially with b over the entire time interval req and oscillates around this.

[0233] The initial value QCsp(t1) The target value for the carbon oxide supply flow is equal to 10 Nm³ / h.3 / h, and the initial value QCref(t1) The reference value for the carbon dioxide input flow is equal to 19 Nm³ / h. 3 / h. In a first time period 601, QCsp less than QCref and the process starts at 10 Nm 3 / h to approximately 19 Nm 3 / h. At about 10 minutes QCsp even QCref and in a second time period 602 the ramp of QCsp on QCref limited, which in turn increases relatively slowly over time.

[0234] At about 20 minutes QCsp equal to the maximum capacity QCmax of the process, and in a third time period 603 the target value is QCsp limited by and is essentially the same QCmax. In the third time period, 603, QCmax less than QCreq and, as in Fig. 6b shows xC,Pmea 610 oscillating behavior. These oscillations are due to the effect of the iterative control of the second embodiment 300 of the first aspect of the present invention. QCsp <QCmax, In this embodiment, 300 QCsp The CO2 supply flow was increased in an attempt to reach the requested value. This increase causes an exceedance. QCmax through QCsp and in response to this, the control method according to the invention reduces the value QCsp to reduce the amount of CO2 that does not enter the methanization process.

[0235] At approximately 150 minutes QCsp even QCreq, and in a fourth time period 604 the target value remains QCsp essentially constant and essentially the same QCreq. During this time period, the iterative control of the second embodiment 300 recognizes that the requested value has been reached and therefore increases QCsp no further. In the fourth time period 604, the amplitude of the oscillations is therefore xC,Pmea 610 significantly reduced (cf. Fig. 6b).

[0236] In a fifth time period 605, at approximately 200 minutes, it takes QCmax abruptly stops, leading to a loss of methanization capacity, which in Fig. 6b through a steep drop from xM,Pmea 610 is reflected. This capacity loss leads to an increase of xH,Pmea 620 and from xC,Pmea 630. As in Fig. As shown in Figure 6c, the iterative control detects the capacity loss in the fifth time period 605 and increases the value of the requested supply ratio b. req In the fifth time period, 605, QCref and consequently QCref reduced to reflect the new value QCmax to correspond. In the fifth time period 605, the method of the present invention varies. QCsp so that after about 10 minutes from the loss of capacity QCsp the maximum value of the carbon dioxide input flow has been reached (see above). Fig. 6a). At about 20 minutes QCsp equal to the maximum capacity QCmax of the process.

[0237] In a sixth time period, 606, the target value is QCsp limited by and essentially the same QCmax which is smaller than QCreq. As in Fig. As shown in Figure 6b, the target value for this time period is 606. QCsp an oscillating behavior that increases over time.

Claims

[1] Computer-implemented method for iteratively controlling a feed stream of a first reactant of a methanation process in a reactor, wherein the methanation process is carried out in the reactor and produces a product gas using a feed gas, wherein the feed gas comprises a first reactant and a second reactant, wherein the first reactant is one of dihydrogen and carbon oxide and the second reactant is the other of dihydrogen and carbon oxide, wherein the method comprises the following steps: - Initiating the calculation of a first setpoint for the supply flow of the first reactant (QHsp(t2),QCsp(t2)) and - Initiating the change in the supply flow of the first reactant according to the first setpoint of the supply flow of the first reactant (QHsp(t2),QCsp(t2)), where the calculation of the first setpoint of the supply flow of the first reactant (QHsp(t2),QCsp(t2)) is performed using initial information, where the initial information indicates whether an estimated value of an initial difference between an estimate of the feed ratio at a first control iteration and an initial requested value of the feed ratio (b) is available. req (t1)) is positive or negative in the first tax iteration, where the feed ratio is the ratio between the feed rate of the first reactant and the feed rate of the second reactant, and where the first information is obtained using a first set of measured physical quantities of the product gas. (xC,Pmea(t1),xC,Mmea(t1)) is generated and whereby the first set of measured physical quantities (xC,Pmea(t1),xC,Mmea(t1)) indicates the ratio between a first value of the amount of carbon oxide in the product gas at the first control iteration and a first value of the amount of methane in the product gas at the first control iteration. [2] Method according to the preceding claim, wherein the calculation of the first setpoint of the supply flow of the first reactant (QHsp(t2),QCsp(t2)) corresponding to a first target value of the supply ratio (b sp (t2)) is carried out, wherein, If, according to the first information, the estimate of the first difference is positive, the first target value of the supply ratio (b) sp (t2)) lower than a second requested value of the supply ratio (b req (t2)) is, where, If, according to the first information, the estimate of the first difference is negative, the first target value of the supply ratio (b) sp (t2)) greater than the second requested value of the supply ratio (breq (t2)) is, where the second requested value of the supply ratio (b req (t2)) is the requested value of the input ratio at a second control iteration, where the first control iteration precedes the second control iteration in time. [3] Method according to one of the preceding claims, wherein the calculation of the first setpoint of the supply flow of the first reactant (QHsp(t2),QCsp(t2)) a calculation of a first value (f b,1 ) of a first function includes, where the first function (e b ) is an increasing function of the difference between an estimated and a requested supply ratio, and the first value (f b,1 ) of the first function is the value of the first function at the estimated value of the first difference, and where, if the first reactant is dihydrogen, the first setpoint of the feed flow of the first reactant (QHsp(t2),QCsp(t2)) a decreasing function of the first value (f b,1 ) of the first function and, if the first reactant is carbon oxide, the first setpoint of the feed rate of the first reactant (QHsp(t2),QCsp(t2)) an increasing function of the first value (f b,1 ) of the first function. [4] A method according to any of the preceding claims, further comprising the following steps: - Initiating the calculation of a second setpoint for the supply flow of the second reactant (QR2sp(t2)), where the calculation of a second setpoint for the supply flow of the second reactant (QR2sp(t2)) using at least one first setpoint of the supply flow of the second reactant (QR2sp(t1)) and a ramp rate of the feed stream of the second reactant (u R2,F ) is carried out; and - Initiating the change in the supply flow of the second reactant according to the second setpoint of the supply flow of the second reactant (QR2sp(t2)), where, if the first setpoint of the supply flow of the second reactant (QR2sp(t1)) is greater than a first requested value of the supply flow of the second reactant (QR2req(t2)), the second setpoint of the supply flow of the second reactant (QR2sp(t2)) is smaller than the first setpoint of the supply flow of the second reactant (QR2sp(t1)), and where, if the first setpoint of the supply flow of the second reactant (QR2sp(t1)) is smaller than the first requested value of the supply flow of the second reactant (QR2req(t2)), the second setpoint of the supply flow of the second reactant (QR2sp(t2)) is greater than the first setpoint of the supply flow of the second reactant (QR2sp(t1)). [5] Method according to any of the preceding claims, wherein the calculation of the first setpoint of the supply flow of the first reactant (QHsp(t2),QCsp(t2)) is performed using a second piece of information, where the second piece of information indicates whether an estimated value of a second difference between an estimate of the extent of the methanization process in the first control iteration and a requested value (y) is obtained. req (t1)) the extent of the methanization process at the first control iteration is positive or negative. [6] Method according to the preceding claim, further comprising the following steps: - Initiating the calculation of a third setpoint for the supply flow of the second reactant (QR2sp(t2)), where the calculation of the third setpoint of the supply flow of the second reactant (QR2sp(t2)) using a first reference value of the feed current of the second reactant (QR2ref(t1)) during the first control iteration and a first value of the feed flow of the second reactant (QR2(1)) is carried out; and - Initiating the change in the supply flow of the second reactant according to the third setpoint of the supply flow of the second reactant (QR2sp(t2)), where the third setpoint is the feed flow of the second reactant (QR2sp(t2)) equal to the minimum between a second reference value of the supply current of the second reactant (QR2ref(t2)) in the second control iteration and the first value of the feed flow of the second reactant (QR2(1)) is, where, if, according to the second piece of information, the estimated value of the second difference is positive, the second reference value of the feed stream of the second reactant (QR2ref(t2)) greater than the first reference value of the feed current of the second reactant (QR2ref(t1)) is, and if, according to the second piece of information, the estimated value of the second difference is negative, the second reference value of the feed stream of the second reactant (QR2ref(t2)) smaller than the first reference value of the feed current of the second reactant (QR2ref(t1)) is. [7] Method according to the preceding claim, wherein the calculation of the first setpoint of the supply flow of the first reactant (QHsp(t2),QCsp(t2)) a calculation of a first value (f y,1 ) a second function includes, where the second function is an increasing function of the difference between an estimated extent of the methanation process and a requested extent of the methanation process, and the first value (f y,1 ) the value of the second function at the estimated value of the second difference is, where the second reference value is the feed stream of the second reactant (QR2ref(t2)) proportional to the first reference value of the feed flow of the second reactant (QR2ref(t1)) is and an increasing function of the first value (f y,1 ) of the second function. [8] Method according to any one of claims 5 to 7, wherein the calculation of the first setpoint of the supply flow of the first reactant (QHsp(t2),QCsp(t2)) a calculation of a first value (g y,1 ) a third function includes, where the third function is an increasing function of the difference between an estimated extent of the methanation process and a requested extent of the methanation process, and the first value (g y,1 ) the value of the third function at the estimated value of the second difference is, where, if the first reactant is dihydrogen, the first setpoint of the feed flow of the first reactant (QHsp(t2),QCsp(t2)) a decreasing function of the first value (g y,1 ) of the third function, and if the first reactant is carbon oxide, the first setpoint of the feed rate of the first reactant (QHsp(t2),QCsp(t2)) an increasing function of the first value (g y,1 ) of the third function. [9] Method according to any of the preceding claims, wherein the calculation of the first setpoint of the supply flow of the first reactant (QHsp(t2),QCsp(t2)) includes: - Generating the first piece of information using the first set of measured physical quantities (xC,Pmea(t1),xC,Mmea(t1)). [10] A method according to any of the preceding claims, wherein the methanization process is carried out in a first culture medium in the reactor, the first culture medium comprising water and an additive compound, the method further comprising the following steps: - Initiating the calculation of an initial target value for the dosage rate of the additional compound (Qadsp(t2)), where the calculation of the first target value of the dosing rate of the additional connection (Qadsp(t2)) using a value (n ad ) the concentration of the additive compound in the first culture medium and a fourth target value of the carbon oxide supply flow (QCsp(t1)) This occurs so that the first target value of the dosing rate of the additional compound is reached. (Qadsp(t2)) is suitable to compensate for water runoff in the first culture medium; and - Initiating the change in the dosing rate of the auxiliary connection according to the first setpoint of the dosing rate of the auxiliary connection. (Qadsp(t2)), where the first target value of the dosing rate of the additional compound (Qadsp(t2)) proportional to the value (n ad ) the concentration of the additive compound in the reactor and the fourth setpoint of the carbon oxide feed stream (QCsp(t1)) is. [11] A method according to any of the preceding claims, wherein the methanization process is carried out in a second culture medium in the reactor, the second culture medium comprising water and an alkalinity-regulating compound, the method further comprising the following steps: - Initiating the calculation of an initial target value for the dosage rate of the alkalinity-regulating compound (Qalsp(t2)), where the calculation of the first target value of the dosage rate of the alkalinity-regulating compound (Qalsp(t2)) using the first requested value of the feed stream carbon oxide (QCreq(t2)) is carried out so that the first target value of the dosage rate of the alkalinity-regulating compound is reached. (Qalsp(t2)) is suitable to compensate for the acidification of the second cultural medium; and - Initiating the change in the supply flow of the alkalinity-regulating compound additive according to the first setpoint of the dosage rate of the alkalinity-regulating compound. (Qalsp(t2)), where the first setpoint of the dosage rate of the alkalinity-regulating compound (Qalsp(t2)) proportional to the first requested value of the carbon oxide supply flow (QCreq(t2)) is. [12] Data processing system (150) comprising a processing unit (158) configured to perform the method according to any of the preceding claims. [13] Reactor arrangement (100) for carrying out a methanization process, wherein the reactor arrangement comprises the data processing system (150) according to the preceding claim. [14] Computer program product comprising instructions which, when the program is executed by a data processing system, cause the system to execute the method according to any one of claims 1 to 11. [15] Computer-readable storage medium with instructions which, when executed by a data processing system, cause the system to execute the method according to any one of claims 1 to 11.

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