Process and method for separating carbon dioxide from combustion exhaust gas flow

Abstract

A process for separating carbon dioxide from a combustion exhaust gas flow, wherein an open combustion exhaust gas chimney having a combustion exhaust gas inlet and a combustion exhaust gas outlet is connected via first and second conduits between a first combustion exhaust gas generating unit and a second unit configured to capture carbon dioxide. A booster located in the first conduit is configured to draw combustion exhaust gas from the first unit and maintain a constant pressure within the first unit. Flow measurement, which measures the actual combustion exhaust gas flow rate in the first conduit, is performed in the first conduit upstream of the combustion exhaust gas chimney, the pressure within the first unit is controlled using a control unit, and the actual combustion exhaust gas flow rate in the first conduit is used as an input signal to the control unit.

Description

Technical Field

[0001] The present invention relates to a process for separating carbon dioxide from a combustion exhaust gas stream. In particular, the present invention relates to such a process with improved control. Furthermore, the present invention relates to an apparatus for separating carbon dioxide from a combustion exhaust gas stream. In particular, the present invention relates to such an apparatus with improved control.

Background Art

[0002] Published European Patent Application No. 22161775 discloses, in one embodiment, a process for separating carbon dioxide from a combustion exhaust gas stream, wherein a combustion exhaust gas stack is openly integrated into a combustion exhaust gas flow path between a combustion exhaust gas generating unit and a carbon dioxide separation unit. The term "openly integrated" as used herein is understood to mean that the entire system is always open to the atmosphere through the upper outlet of the combustion exhaust gas stack.

[0003] Such "open integration" has the advantage that it can be particularly easily implemented for the retroactive modification of existing industrial plants when retroactively providing carbon dioxide separation for the treatment of combustion exhaust gases. Integrating the carbon dioxide separation unit upstream of the combustion exhaust gas stack via a branch is often impossible due to space constraints.

[0004] However, open integration has problems in terms of controlling the pressure in the combustion exhaust gas generating unit. The pressure in the combustion exhaust gas generating unit and in the combustion exhaust gas flow path must be adjusted so that, during normal operation when the carbon dioxide separation unit is operating, if any, only a minimal amount of combustion exhaust gas is discharged from the combustion exhaust gas stack into the atmosphere.

[0005] Pressure control within the combustion exhaust gas generation unit is achieved, for example, by the rotational speed of a blower installed in the combustion exhaust gas flow path. This blower draws combustion exhaust gas from the combustion exhaust gas generation unit and increases the pressure in the combustion exhaust gas flow path, thereby transporting it to the carbon dioxide separation unit. To ensure the latter, an additional blower may be placed in the combustion exhaust gas flow path downstream of the combustion exhaust gas chimney.

[0006] In the event of a malfunction, for example, if the carbon dioxide separation unit suddenly stops, a large amount of combustion exhaust gas must be immediately diverted to the combustion exhaust gas chimney. This changes the flow and pressure conditions both downstream and upstream of the combustion exhaust gas blower.

[0007] This can cause the pressure inside the combustion exhaust gas generation unit to deviate from the set value and rapidly reach the high-pressure or low-pressure operating set value. Upon reaching this operating set value, the combustion exhaust gas generation unit may shut down. If this unit is, for example, a steam reformer, synthesis gas production will cease. Such a scenario, caused by a failure in the carbon dioxide separation unit, is undesirable and should be avoided.

[0008] Measuring the pressure state within a combustion exhaust gas system and its changes as input signals is not optimal for quickly addressing the aforementioned types of problems via control means.

[0009] During a malfunction, natural convection draws in combustion exhaust gases through the chimney, which indeed causes a change in the pressure state of the combustion exhaust gas chimney. This results from the temperature difference across the chimney height and the overall pressure loss due to the ratio of the combustion exhaust gas flow rate. If a carbon dioxide separation unit is located downstream, the entire combustion exhaust gas passes through the chimney, resulting in a particularly large overall pressure loss in the chimney, and therefore a change in the pressure at the combustion exhaust gas outlet of the combustion exhaust gas generation unit. However, this pressure change is only detected after a malfunction has occurred. Following the principle of such feedback control, this type of control is slow to respond and therefore not optimal.

[0010] This slow reaction means that if pressure control during normal operation is not functioning properly, the combustion exhaust chimney may continue to draw in ambient air indefinitely, which could reduce the efficiency and / or capacity of the downstream carbon dioxide separation process and / or shorten the lifespan of the adsorption medium being used. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] Therefore, broadly speaking, the objective of the present invention is to overcome the aforementioned shortcomings of the prior art. [Means for solving the problem]

[0012] Specifically, the objective of this invention is to improve the control of pressure as a control variable within the combustion exhaust gas generation unit, thereby enabling the system to respond more quickly to the effects of fault variables than when controlled by measuring pressure as a command variable.

[0013] These objectives are achieved, at least in part, by processes and apparatus according to the independent claims. Further advantageous embodiments are specified in the dependent claims. The features presented in the claims and this description can be combined with each other in any technically advantageous manner.

[0014] Terms such as "possess," "equip," or "contain" do not rule out the possibility of further elements, components, etc. The indefinite article "a" does not rule out the possibility of multiple entities.

[0015] The present invention relates to a process for separating carbon dioxide from a combustion exhaust gas flow, wherein a first unit is configured to generate a carbon dioxide-containing combustion exhaust gas flow in a combustion space, and a second unit is configured to separate carbon dioxide from the carbon dioxide-containing combustion exhaust gas flow, thereby generating a carbon dioxide product flow; a combustion exhaust gas chimney having a combustion exhaust gas inlet and a combustion exhaust gas outlet is located downstream of the first unit and upstream of the second unit, the first unit is connected to the combustion exhaust gas inlet of the combustion exhaust gas chimney via a first conduit, and the second unit is connected to the combustion exhaust gas outlet of the combustion exhaust gas chimney via a second conduit; a booster, particularly a blower, is located in the first conduit, and the booster is configured to draw combustion exhaust gas from the first unit and maintain a constant pressure within the first unit; in this process, The present invention provides a process characterized in that flow rate measurement for determining the actual combustion exhaust gas flow rate in the first conduit is performed upstream of the combustion exhaust gas chimney within the first conduit, the pressure within the first unit is controlled using a control unit, and the actual combustion exhaust gas flow rate in the first conduit is used as an input signal to the control unit.

[0016] The first unit generates a carbon dioxide-containing combustion flue gas flow in a combustion space. For example, the carbon dioxide-containing combustion flue gas flow contains 5 mol% to 90 mol% carbon dioxide (CO2) on a wet basis and has absolute pressures of 0.5 bar and 2 bar, preferably 0.9 bar and 1.1 bar. The first unit can be any desired unit configured to generate a carbon dioxide-containing combustion flue gas flow. For example, the first unit is a steam reformer. The steam reformer has a combustion space that heats a catalyst-filled reformer tube by the combustion of fuel, generating heat and a combustion flue gas flow. As a further example, the first unit is a combustion heating device that burns fuel to generate heat and a combustion flue gas flow, which can be used for heat exchange or steam generation in a process.

[0017] The pressure controlled in the first unit is a control variable of the process, particularly the relevant control loop. A booster, especially a blower, is configured to maintain a constant pressure within the first unit, i.e., to adjust it to a predetermined setpoint. In particular, the booster is configured to maintain a constant pressure within the combustion chamber of the first unit, specifically to adjust it to a predetermined setpoint. The control unit preferably outputs an output signal to the booster, which, through an operating variable, maintains a constant setpoint of the control variable, specifically, maintains a constant pressure within the first unit.

[0018] The second unit is configured to separate carbon dioxide from a carbon dioxide-containing combustion flue gas stream and produce a carbon dioxide product stream. The second unit may be any desired carbon dioxide separation unit suitable for producing the carbon dioxide product stream. The carbon dioxide product stream has a higher carbon dioxide concentration than the combustion flue gas stream, in particular. In one example, the carbon dioxide product stream has a carbon dioxide content of at least 50 mol% on a dry basis, preferably at least 75 mol%, and more preferably at least 95 mol% on a dry basis. In particular, the carbon dioxide product stream contains a higher carbon dioxide content in mol% on a dry basis than the combustion flue gas stream in mol% on a wet basis.

[0019] The second unit is preferably a unit that generates a carbon dioxide product flow from a carbon dioxide-containing combustion exhaust gas flow by adsorption of carbon dioxide by an adsorption medium and desorption of carbon dioxide from the adsorption medium. The corresponding processes are well known to those skilled in the art. As an example, and preferably, the second unit is a gas scrubbing unit having an adsorption tower and a desorption tower, in which the adsorption medium binds carbon dioxide by chemical means. The gas scrubbing unit is particularly an amine scrubbing unit.

[0020] It is even more preferable that the second unit is a unit that generates a carbon dioxide product stream from a carbon dioxide-containing combustion exhaust gas stream by condensing carbon dioxide from the carbon dioxide-containing combustion exhaust gas stream at a low temperature. Such a unit is also called a low-temperature unit. Such a unit may further include a distillation apparatus for further purifying the condensed carbon dioxide and one or more membrane apparatus for further separating the accompanying gases.

[0021] The combustion exhaust gas chimney is positioned downstream of the first unit and upstream of the second unit. "Downstream of the first unit" is understood to mean the downstream side of the first unit in the direction of the combustion exhaust gas flow. "Upstream of the second unit" means the upstream side of the second unit in the direction of the combustion exhaust gas flow.

[0022] The first unit is connected to the combustion exhaust gas inlet of the combustion exhaust gas chimney via the first conduit. Therefore, the first conduit is positioned particularly between the first unit and the combustion exhaust gas chimney. The first conduit is specifically a combustion exhaust gas flow path. In one example, the diameter of such a combustion exhaust gas flow path may be greater than 1 m, greater than 3 m, or greater than 5 m. Multiple devices, such as measuring devices, gas conveying devices, and / or heat exchangers, may be integrated into the first conduit. Thus, these devices may form part of the first conduit.

[0023] The second unit is connected to the combustion exhaust gas outlet of the combustion exhaust gas chimney via a second conduit. Therefore, the second conduit is positioned specifically between the second unit and the combustion exhaust gas chimney. The second conduit is, in particular, a combustion exhaust gas flow path. In one example, such a combustion exhaust gas flow path may have a diameter greater than 1 meter, greater than 3 meters, or greater than 5 meters. Multiple devices, such as measuring devices and gas conveying devices, may also be integrated into the second conduit. In particular, devices for pre-treating the combustion exhaust gas flow may be integrated into the first conduit before the combustion exhaust gas flow is introduced into the second unit. Therefore, these devices may form part of the second conduit.

[0024] A combustion exhaust gas chimney is a structure well-known to those skilled in the art that includes a combustion exhaust gas conduit arranged substantially vertically. This conduit has an opening in its upper region or head region for discharging combustion exhaust gas to the environment. The combustion exhaust gas chimney has a combustion exhaust gas inlet and a combustion exhaust gas outlet. The combustion exhaust gas outlet is distinguished from the opening in the head region of the combustion exhaust gas chimney. The combustion exhaust gas inlet and the combustion exhaust gas inlet in the present invention are preferably arranged in the lower region of the combustion exhaust gas chimney, preferably within the lower one-third of the combustion exhaust gas chimney in terms of the vertical length of the combustion exhaust gas chimney.

[0025] A pressure boosting device configured to draw combustion exhaust gas from the first unit and configured or adapted to keep the pressure in the first unit constant is arranged in the first conduit. The pressure boosting device is particularly adapted to keep the pressure in the combustion space of the first unit constant. The pressure boosting device has a suction side and a pressure side. The pressure on the suction side is always lower than the pressure on the pressure side. The pressure boosting device is preferably a blower. The pressure in the first unit can be kept constant, for example, by changing the rotational speed of such a blower. In this case, the rotational speed of the blower is a control variable of the process, particularly an operating variable that affects the pressure in the first unit. When a large amount of combustion exhaust gas is generated in the first unit, the pressure in the first unit can be kept constant by operating the blower at a high speed according to the amount of combustion exhaust gas. When the amount of combustion exhaust gas generated is small, the pressure in the first unit can be kept more constant by reducing the rotational speed of the blower.

[0026] The terms "arranged in the first conduit" and "arranged in the second conduit" are understood to mean, in a mechanical sense, that each respective conduit is interrupted at the relevant location and each respective element arranged in each respective conduit is connected to each respective conduit via an inlet and an outlet.

[0027] According to the present invention, on the upstream side of the combustion exhaust gas chimney, a flow rate measurement for measuring the actual combustion exhaust gas flow rate in the first conduit is performed, and the pressure in the first unit is controlled using a control unit, where the actual combustion exhaust gas flow rate in the first conduit is used as an input signal to the control unit.

[0028] The actual combustion exhaust gas flow rate in the first conduit is output to the control unit as an input signal. In particular, the actual combustion exhaust gas flow rate in the first conduit is used as a command variable in the process, particularly as a command variable of the relevant control loop.

[0029] The combustion exhaust gas flow rate can be measured as a volume flow rate, a mass flow rate, or a molar flow rate.

[0030] The flow rate measurement for measuring the actual combustion exhaust gas flow rate in the first conduit can be carried out upstream or downstream of the pressure boosting device. The flow rate measurement for measuring the actual combustion exhaust gas flow rate is preferably performed on the downstream side of the pressure boosting device.

[0031] Instead of the disadvantageous detection of pressure as a command variable, according to the present invention, it is proposed to use the actual combustion exhaust gas flow rate in the first conduit as a command variable and thus as an input signal to the control device. By using the actual combustion exhaust gas flow rate in the first conduit as an input signal to the control unit, the control is improved and particularly speeded up, and thus, especially in case of a failure that can affect the pressure in the first unit like a control variable as a failure variable, the pressure in the first unit is kept more quickly constant. Based on this input signal, the control unit generates an output signal, which is particularly output to the pressure boosting device and thus is particularly used as a manipulated variable for controlling the pressure in the first unit. As described above, the manipulated variable can be, for example, the rotational speed of the pressure boosting device or the opening angle of a flap element arranged in the first conduit.

[0032] The advantage of capturing the actual combustion flue gas flow rate in the first conduit as a command variable is that it allows for the calculation of combustion flue gas flow rates for various normal and failure scenarios in each plant. This makes it possible to implement a feedforward control concept in the system, which would be impossible if the command variable were based on pressure measurements. Even when a failure does not cause a significant pressure change in the system, it is possible to detect the deviation between the predicted combustion flue gas flow rate and the actually measured combustion flue gas flow rate.

[0033] Accordingly, a preferred embodiment of the process according to the present invention is characterized in that a control unit captures at least one influencing variable suitable for predicting a calculable combustion flue gas flow rate, thereby determining a calculated combustion flue gas flow rate that is expected to flow through a first conduit at that flow rate based on the at least one influencing variable, and the calculated combustion flue gas flow rate in the first conduit is compared with the actual combustion flue gas flow rate in the first conduit.

[0034] In this embodiment, the control unit captures at least one influencing variable, for example, through a measurement suitable for calculating the combustion flue gas flow rate based on this at least one influencing variable. The at least one influencing variable is preferably the flow rate of the starting fuel, which directly affects the amount of combustion flue gas produced and, consequently, the combustion flue gas flow rate. It is also possible to identify multiple influencing variables suitable for calculating the combustion flue gas flow rate. To improve the accuracy of the combustion flue gas flow rate calculation, it is also possible to use influencing variables that do not directly affect the amount of combustion flue gas produced. The important thing is that at least one influencing variable suitable for calculating the expected combustion flue gas flow rate is determined.

[0035] Examples of influencing variables are as follows: - Flow rate of fuel for combustion exhaust gas generation, especially hydrocarbon-containing fuels; - Composition of fuel for generating combustion exhaust gas, particularly the carbon content, hydrogen content, and / or oxygen content of the fuel; - Flow rate of oxidizing agent, especially air, oxygen-rich air, or pure oxygen; - Composition of the oxidizing agent, particularly its oxygen content; - Pressure; - Temperature.

[0036] The two influencing variables mentioned first are a particularly suitable combination for calculating the expected combustion flue gas flow rate in the first conduit. Using the dominant pressure and temperature allows for more precise calculation of the combustion flue gas flow rate. The flow rates of fuel and / or oxidizer can be determined as volumetric flow rates, mass flow rates, or molar flow rates. The composition of the fuel and oxidizer are usually constant, as they are supplied from a source providing a constant composition. Therefore, these variables are usually known and can be incorporated into the calculation as constants.

[0037] A preferred embodiment of the process according to the present invention is characterized in that a combustion exhaust gas flow rate difference is determined by comparing a calculated combustion exhaust gas flow rate in a first conduit with the actual combustion exhaust gas flow rate in the first conduit, and the determined combustion exhaust gas flow rate difference is used as an input signal to a control unit.

[0038] This embodiment of the process is particularly suitable for detecting changes in state caused by fault variables in the components of the first unit and / or the second unit, or between the first and second units. If the combustion flue gas flow rate actually measured in the first line deviates from the calculated combustion flue gas flow rate by a predetermined allowable variation, the control unit can react immediately, and in particular, can react before the fault manifests as a pressure difference in the first conduit due to the influence of each fault variable.

[0039] A preferred embodiment of the process according to the present invention is characterized in that the generation of combustion exhaust gas in the combustion space of a first unit is carried out by combustion of hydrocarbon-containing input material and oxygen-containing oxidizer via at least one burner, wherein the influencing variable is the flow rate of oxidizer supplied to at least one burner and / or the flow rate of hydrocarbon-containing input material supplied to at least one burner.

[0040] The "and" option is preferred. One or more burners may be placed within the combustion space of the combustion exhaust gas generation unit. Multiple burners are preferred. In either case, the control unit captures the total amount, i.e., total flow rate, of hydrocarbon-containing initiating material and / or oxidizer supplied to the burner or group of burners as an influencing variable. As described above, the composition of fuel and oxidizer in this context can often be assumed to be constant.

[0041] A preferred embodiment of the process according to the present invention is characterized in that the hydrocarbon-containing input material is a fuel gas, particularly natural gas, and / or the hydrocarbon-containing input material is an off-gas from a pressure swing adsorption unit.

[0042] When the first unit is a steam reformer and a water-gas shift reactor is located downstream thereof, the corresponding plant generally includes a pressure swing adsorption unit that produces high-purity hydrogen and off-gas. The off-gas typically contains not only carbon dioxide but also methane and carbon monoxide. Both gases are available as fuel for combustion in the fuel space of the first unit.

[0043] A preferred embodiment of the process according to the present invention is characterized in that a flow measurement is performed in a second conduit downstream of the combustion exhaust gas chimney to measure the actual combustion exhaust gas flow rate in the second conduit, and the actual combustion exhaust gas flow rate in the second conduit is used as an input signal to a control unit.

[0044] In this embodiment as well, the actual combustion flue gas flow rate is measured in the second conduit, and therefore downstream of the combustion flue gas chimney. The actual combustion flue gas flow rate in the second conduit may be measured as a volumetric flow rate, mass flow rate, or molar flow rate. The actual combustion flue gas flow rate in the second conduit may be output to the control unit as a further input signal. Thus, the actual combustion flue gas flow rate in the second conduit is a further command variable for the process, in particular the applicable control loop. If a further booster, especially a blower, is located in the second conduit, i.e., downstream of the combustion flue gas chimney and upstream of the second unit, the control of the process can be particularly improved. The booster upstream of the combustion flue gas chimney and the further booster downstream of the combustion flue gas chimney may be adapted to each other so as to minimize the combustion flue gas flow rate in the combustion flue gas chimney. Here, the expression "combustion flue gas flow rate in the combustion flue gas chimney" is understood to mean the amount of combustion flue gas discharged into the atmosphere through the combustion flue gas chimney. If the combustion exhaust gas flow rate is also measured in the second conduit and a further booster is present, it is preferable to measure the combustion exhaust gas flow rate in the second conduit upstream of the further booster and downstream of the combustion exhaust gas chimney. In a preferred embodiment, the further booster, in particular a blower, is located in the second conduit.

[0045] Therefore, a preferred embodiment of this process is characterized in that the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney is measured based on the difference between the actual combustion exhaust gas flow rate in the first conduit and the actual combustion exhaust gas flow rate in the second conduit, and the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney is used as an input signal to the control unit.

[0046] The control can be further improved if the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney is also output as an output signal to the control unit. In this case, the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney is determined as an additional command variable for the process, particularly for the relevant control loop. As mentioned above, this combustion exhaust gas flow rate in the combustion exhaust gas chimney is determined indirectly by differential calculation.

[0047] One embodiment of the process according to the present invention involves removing sulfur oxides (SO4) from the combustion exhaust gas flow. x A combustion exhaust gas scrubbing device for removing (and cooling the combustion exhaust gas flow) is installed in the second conduit and upstream of the second unit, and a flow measurement for measuring the actual combustion exhaust gas flow rate in the second conduit is performed upstream of the combustion exhaust gas scrubbing device.

[0048] In this embodiment, the flow rate measurement in the second conduit is performed upstream of the combustion flue gas scrubber. The combustion flue gas scrubber is used to pre-treat the combustion flue gas before it is introduced into the second unit for carbon dioxide separation. The combustion flue gas scrubber is used in particular for cooling the combustion flue gas flow and removing sulfur dioxide from the combustion flue gas flow. Generally, a certain amount of water is also removed from the combustion flue gas flow by condensation. Therefore, the combustion flue gas flow in the second conduit upstream of the combustion flue gas scrubber and the combustion flue gas flow upstream of the combustion flue gas chimney are comparable in terms of composition, pressure, and temperature. Thus, it is advantageous to measure the flow rate of the combustion flue gas flow in the second conduit upstream of the combustion flue gas scrubber. Otherwise, inaccurate, i.e., non-representative values ​​will be obtained, particularly with regard to the indirect measurement of the combustion flue gas flow rate in the combustion flue gas chimney.

[0049] If a further pressurizing device, particularly a blower, is present in the second conduit, it is preferable to position it downstream of the combustion exhaust gas cleaning device and upstream of the second unit.

[0050] A preferred embodiment of the process according to the present invention is characterized in that a booster, in particular a blower, comprises a rotating element, and a control unit controls the pressure in a first unit by the rotational speed of the rotating element via an output signal.

[0051] It is preferable that the combustion exhaust gas flow rate in the first conduit is controlled via the rotational speed of a rotating element, where the rotational speed is a process operating variable, particularly an operating variable of the control loop in question. This operating variable is determined by an output signal from the control unit resulting from one or more input signals to the control unit. By changing the rotational speed of the rotating element of the booster, the pressure as a control variable is kept constant within the first unit even when process conditions change, particularly when conditions change due to the influence of a fault variable.

[0052] Furthermore, a flap element having a variable flow cross-section may be placed within the first conduit, and a control unit may be provided to additionally control the pressure within the first unit by the size of the flow cross-section of the flap element via an output signal.

[0053] The control unit can further control the pressure within the first unit using another output signal that changes the size of the flow cross-section of the flap element. The size of the flow cross-section of the flap element can be considered an operating variable of the process, particularly an operating variable of the control loop in question, as can the rotational speed of the booster. The flap element may be any flap element known to those skilled in the art. Crucially, the size of the flow cross-section of the flap element is changeable, i.e., it can be made larger or smaller. This changes the flow cross-section within the first conduit. Examples of flap elements include shut-off flaps, double flaps, louver flaps, pivot flaps, and sliders.

[0054] A flap element with a variable flow cross-section may also be placed inside the second conduit, thereby providing control over the pressure within the first unit.

[0055] A preferred embodiment of the process according to the present invention is characterized in that the oxygen concentration in the combustion exhaust gas flow is measured in a first conduit and / or a second conduit, and the measured oxygen concentration is used as an input signal to a control unit.

[0056] Therefore, oxygen concentration can function as a further command variable for controlling the process.

[0057] It is preferable that the oxygen concentration measurement is performed in a second conduit located upstream of the second unit.

[0058] Measuring the oxygen concentration in the combustion flue gas stream can improve the quality of control, particularly in determining fault variables. For example, a rapid increase in the oxygen concentration in the combustion flue gas stream may indicate a fuel supply shortage. This could also mean that air entering from the combustion flue gas chimney has flowed into the system and reached the second unit. Excessive oxygen concentration in the combustion flue gas is generally problematic for the second unit because, firstly, oxygen is difficult to separate, and secondly, it can lead to a decrease in the performance of the second unit. This is especially noticeable when using amine cleaning equipment. Therefore, detecting the oxygen concentration in the combustion flue gas stream is particularly suitable for developing alarm scenarios and detecting underlying problems during ongoing operation.

[0059] The present invention further relates to a device for separating carbon dioxide from a combustion exhaust gas flow, A first unit that generates a carbon dioxide-containing combustion exhaust gas flow within the combustion space, A second unit configured to separate carbon dioxide from a carbon dioxide-containing combustion exhaust gas flow and thus generate a carbon dioxide product flow, A combustion exhaust gas chimney located downstream of the first unit and upstream of the second unit, having a combustion exhaust gas inlet and a combustion exhaust gas outlet, connected to the first unit via a first conduit through the combustion exhaust gas inlet, and connected to the second unit via a second conduit through the combustion exhaust gas outlet, A pressurizing device, particularly a blower, is positioned in a first conduit and configured to draw in combustion exhaust gas from a first unit and maintain a constant pressure within the first unit. In a device equipped with, A flow measuring device is placed inside the first conduit, and the flow measuring device is adapted to measure the actual combustion exhaust gas flow rate inside the first conduit. The pressure inside the first unit can be controlled using a control unit, and the actual combustion exhaust gas flow rate inside the first conduit can be used as an input signal to the control unit. The present invention provides a device characterized by the following features.

[0060] A preferred embodiment of the apparatus according to the present invention is characterized in that a control unit is enabled to capture at least one influencing variable suitable for predicting a calculable combustion flue gas flow rate, thereby enabling the determination of a calculated combustion flue gas flow rate that is expected to flow through a first conduit at that flow rate, based on at least one influencing variable, and the calculated combustion flue gas flow rate in the first conduit can be compared with the actual combustion flue gas flow rate in the first conduit.

[0061] A preferred embodiment of the apparatus according to the present invention is characterized in that the combustion exhaust gas flow rate difference can be determined by comparing the calculated combustion exhaust gas flow rate in the first conduit with the actual combustion exhaust gas flow rate in the first conduit, and the determined combustion exhaust gas flow rate difference can be used as an input signal to the control unit.

[0062] A preferred embodiment of the apparatus according to the present invention is characterized in that the first unit comprises at least one burner in a combustion space, the burner generates a combustion exhaust gas flow by combustion of a hydrocarbon-containing input material and an oxygen-containing oxidizer, the influencing variable being the flow rate of the oxidizer supplied to at least one burner, and / or the influencing variable being the flow rate of the hydrocarbon-containing input material supplied to at least one burner.

[0063] A preferred embodiment of the apparatus according to the present invention is characterized in that the hydrocarbon-containing input material is a fuel gas, particularly natural gas, and / or the hydrocarbon-containing input material is an off-gas from a pressure swing adsorption unit.

[0064] A preferred embodiment of the apparatus according to the present invention is characterized in that a flow rate measuring device is located in a second conduit downstream of the combustion exhaust gas chimney for measuring the actual combustion exhaust gas flow rate in the second conduit, and the actual combustion exhaust gas flow rate in the second conduit is available as an input signal to a control unit.

[0065] A preferred embodiment of the apparatus according to the present invention is characterized in that the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney can be determined based on the difference between the actual combustion exhaust gas flow rate in the first conduit and the actual combustion exhaust gas flow rate in the second conduit, and the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney can be used as an input signal to the control unit.

[0066] A preferred embodiment of the apparatus according to the present invention is one in which sulfur oxides (SO4) are removed from the combustion exhaust gas flow. x A combustion exhaust gas cleaning device for removing (and cooling the combustion exhaust gas flow) is located in the second conduit and upstream of the second unit, and a flow measuring device for measuring the actual combustion exhaust gas flow rate in the second conduit is located upstream of the combustion exhaust gas cleaning device.

[0067] A preferred embodiment of the apparatus according to the present invention is characterized in that a booster, particularly a blower, comprises a rotating element, and a control unit controls the pressure within a first unit by the rotational speed of the rotating element via an output signal.

[0068] A preferred embodiment of the apparatus according to the present invention is characterized in that a flap element having a variable flow cross-section is arranged in a first conduit, and a control unit further controls the pressure in the first unit by the size of the flow cross-section of the flap element via an output signal.

[0069] A preferred embodiment of the apparatus according to the present invention is characterized in that a measuring device for measuring the oxygen concentration in the combustion exhaust gas flow is located in a first conduit and / or a second conduit, and the measured oxygen concentration can be used as an input signal to a control unit.

[0070] Exemplary Embodiments The present invention will now be made more concrete with reference to the figures. Figure 1 shows a particularly preferred exemplary embodiment, but the present invention is not limited thereto. The figures and the proportions shown therein are approximate and not to scale. [Brief explanation of the drawing]

[0071] [Figure 1] Figure 1 shows an apparatus according to the present invention for separating carbon dioxide, suitable for carrying out the process according to the present invention. [Modes for carrying out the invention]

[0072] Figure 1 shows a configuration according to the present invention comprising a first unit 1, a second unit 2, and a combustion exhaust gas chimney 4. The combustion exhaust gas chimney 4 is connected to the first unit 1 via a combustion exhaust gas inlet 6 through a first conduit 5. The combustion exhaust gas chimney 4 is further connected to the second unit 2 via a combustion exhaust gas outlet 7 through a second conduit 8.

[0073] The first unit 1 is configured as a steam reformer and has a combustion space 3 in which multiple burners 17 generate combustion flue gas, which is drawn out of the combustion space 3 of the first unit 1 using a booster 9. The steam reformer has multiple reformer tubes 18 filled with catalysts, in which a natural gas-steam mixture from conduits 14 is converted into a synthesis gas mixture, which is drawn out of the steam reformer via multiple conduits 19 for further processing (not shown). Since the steam reforming reaction is an endothermic reaction, the reformer tubes 19 are heated by multiple burners 17 located at the top of the combustion space. Fuel and an oxidizer (e.g., air) are supplied to the burners 17 via conduits 15 and 16. The combustion chamber 3 of the first unit 1 is sometimes called the radiating zone of the steam reformer. The combustion flue gas flow generated by the burners 17 is drawn out of the combustion space 3 via a first conduit 5. A heat recovery device 26 is located inside the first conduit 5. Even when shown only as a single heat exchanger, the heat recovery unit 26 may comprise a series of multiple heat exchangers. The heat recovery unit 26 serves to cool the combustion exhaust gas flow while simultaneously heating other media, for example, for steam generation.

[0074] The combustion exhaust gas chimney 4 is integrated into this configuration in an open state. That is, while this configuration is in operation, it is always in contact with the environment through the opening 34 in the upper region of the combustion exhaust gas chimney 4. The combustion exhaust gas chimney 4 is integrated into this configuration downstream of the first unit 1 and upstream of the second unit 2.

[0075] The first conduit 5 and the second conduit 8 are configured as combustion exhaust gas flow paths in at least some sections. The heat recovery device 26 and the booster device 9, configured as a blower, are located in the first conduit and are fluidly connected to it. The combustion exhaust gas cleaning device 20 and a further booster device 21, similarly configured as a blower, are located in the second conduit 8 and are fluidly connected to it.

[0076] The second unit 2 is only partially shown in Figure 1. The second unit 2 is adapted to separate carbon dioxide from the combustion flue gas flow introduced into the second unit 2 via the second conduit 8. For this purpose, the second unit 2 includes an adsorption tower for chemical adsorption of carbon dioxide using a chemiosorbent and a desorption tower (not shown) for desorption of carbon dioxide from the adsorbent. As the adsorption medium, a regenerated amine solution, i.e., an amine solution from which carbon dioxide has been removed, is introduced into the second unit 2 via conduit 23. The adsorption medium 25 flows from top to bottom, and the combustion flue gas to be purified flows from bottom to top. The combustion flue gas from which carbon dioxide has been removed is withdrawn from the second unit 2 via conduit 22. The adsorption medium containing carbon dioxide is withdrawn from the second unit 2 via conduit 24 and supplied to the desorption tower (not shown). In the desorption tower, carbon dioxide is removed by introducing steam into the amine solution containing carbon dioxide. The resulting carbon dioxide flow is withdrawn from the desorption tower and sent for further processing (drying, refinement, compression) (not shown). The resulting carbon dioxide stream can then be segregated as a carbon dioxide product stream or sent for reuse, for example, as a raw material for methanol synthesis.

[0077] The combustion exhaust gas scrubbing device 20, located within the second conduit 8, is used to pre-treat the combustion exhaust gas flow before it is introduced into the second unit 2 to adsorb carbon dioxide. The combustion exhaust gas scrubbing device 20 is particularly used for further cooling of the combustion exhaust gas flow and for removing sulfur oxides (SO4) using an aqueous cleaning medium 28. X It is used to remove ) the cleaning medium 28. The cleaning medium 28 circulates within the combustion exhaust gas cleaning device using a recirculation pump 27 and a conduit 30 and is continuously cooled via a heat exchanger 32. For the regeneration of the cleaning medium, a portion of the circulating cleaning medium is constantly drawn out via a conduit 31, and a corresponding portion of new cleaning medium is supplied to the combustion exhaust gas cleaning device 20 via a conduit 29.

[0078] The booster 9 is used to maintain a constant pressure in the combustion space 3 of the first unit 1. As mentioned above, the first booster 9 is configured as a blower. The pressure can be kept constant by controlling the rotation speed of the blower 9. For this reason, flow rate measurement 10a is performed downstream of the blower 9 and upstream of the combustion exhaust gas chimney 4 to measure the flow rate of the combustion exhaust gas at this point. This actual combustion exhaust gas flow rate in the first conduit 5 is output as an input signal 12a to the control unit 33 via a signal conduit. The flow rate of fuel in the fuel conduit 15 and the flow rate of oxidizer in the oxidizer conduit 16 are further output to the control unit as input signals 12c / 12d via signal lines. From input signals 12c and 12d, the control unit 33 determines the flow rates of fuel and oxidizer, as well as the combustion exhaust gas flow rate calculated based on known fuel composition (especially carbon and hydrogen content) and oxidizer composition (especially oxygen content). The control unit 33 can compare the calculated combustion exhaust gas flow rate with the combustion exhaust gas flow rate actually measured by the flow rate meter 10a. Under stable operating conditions, the absolute values ​​of these two measured combustion exhaust gas flow rates should be approximately equal. If the difference between the calculated value and the actual value exceeds a preset maximum value, a system failure is suspected, and the control unit 33 can respond immediately using this feedforward control principle.

[0079] Furthermore, the control of this configuration can be further improved by performing a flow rate measurement 10b in the second conduit 8 located downstream of the combustion exhaust gas chimney 4, which measures the actual combustion exhaust gas flow rate in the second conduit downstream of the combustion exhaust gas chimney 4. This allows the combustion exhaust gas flow rate through the combustion exhaust gas chimney 4 to be determined by calculating the difference between the actual combustion exhaust gas flow rates in the first conduit 5 and the second conduit 8. Ideally, this should be controlled via a blower and optionally further elements (e.g., flap elements) so that its magnitude is "zero". The actual combustion exhaust gas flow rate in the second conduit 8 is output as an input signal 12b to the control unit 33 via a signal conduit. Based on the information on the actual combustion exhaust gas flow rates in the first conduit 5 and the second conduit 8, and the calculated combustion exhaust gas flow rate information, the control of the booster 9 can be further optimized. This is done by outputting the output signal 13a from the control unit 33 to the booster 9 via a signal conduit. This output signal is calculated by the control unit 33 based on at least one of the input signals 12a, 12b, 12c, and 12d. The control of this configuration can be further improved by the control unit 33 outputting an output signal 13b to an additional booster 21 via a signal conduit. This allows for better consideration of the interaction between the two boosters 9 and 21, and thus optimizes the control, particularly in minimizing the actual combustion exhaust gas flow rate through the combustion exhaust gas chimney 4. [Explanation of symbols]

[0080] 1. First unit (steam reformer) 2. Second unit (separation) 3. Combustion space 4. Combustion exhaust gas chimney 5. First conduit (combustion exhaust gas conduit) 6. Combustion exhaust gas inlet 7 Combustion exhaust gas outlet 8. Second conduit (combustion exhaust gas conduit) 9. Pressure booster (blower) 10a, 10b flow measurement 11 Control Unit 12a, 12b, 12c, 12d Input signals 13a, 13b Output signals 14 Natural gas pipeline 15 Fuel conduit 16 Oxidizing agent conduit 17 Burner 18. Modifier tube 19 Synthetic gas conduits 20 Combustion exhaust gas cleaning device 21. Pressure booster (blower) 22 Combustion exhaust gas conduit (for purified combustion exhaust gas) 23 (Regenerated) Conduit for Adsorption Media 24 Conduit for adsorption media (containing carbon dioxide) 25 Adsorption media 26 Heat recovery system 27 Recirculation pump 28 Cleaning media 29. Conduit (for fresh cleaning medium) 30 Conduits (for circulating cleaning media) 31. Conduit (for used purification media) 32 Heat exchanger 33 Control Unit 34 Combustion exhaust gas chimney opening

Claims

1. A method for separating carbon dioxide from combustion exhaust gas flow, The first unit (1) generates a carbon dioxide-containing combustion exhaust gas flow within the combustion space (3), The second unit (2) is configured to separate carbon dioxide from the carbon dioxide-containing combustion exhaust gas flow, and therefore the second unit generates a carbon dioxide product flow. A combustion exhaust gas chimney (4) having a combustion exhaust gas inlet (6) and a combustion exhaust gas outlet (7) is positioned downstream of the first unit (1) and upstream of the second unit (2). The first unit (1) is connected to the combustion exhaust gas inlet (6) of the combustion exhaust gas chimney (5) via the first conduit (5), and the second unit (2) is connected to the combustion exhaust gas outlet (7) of the combustion exhaust gas chimney (5) via the second conduit (8). In a method in which a booster device (9), particularly a blower, is arranged in the first conduit (5), and the booster device (9) is configured to draw in combustion exhaust gas from the first unit (1) and maintain a constant pressure within the first unit (1), A method characterized in that a flow rate measurement (10a) for measuring the actual combustion exhaust gas flow rate in the first conduit (5) is performed in the first conduit (5) upstream of the combustion exhaust gas chimney (5), the pressure in the first unit (1) is controlled using a control unit (33), and the actual combustion exhaust gas flow rate in the first conduit (5) is used as an input signal (12a) to the control unit.

2. The control unit (33) captures at least one influencing variable suitable for predicting the calculable combustion exhaust gas flow rate, thereby, Based on the aforementioned at least one influencing variable, the calculated combustion exhaust gas flow rate is determined, which is expected to be the flow rate at which the combustion exhaust gas will flow through the first conduit (5). The method according to claim 1, characterized in that the calculated combustion exhaust gas flow rate in the first conduit (5) is compared with the actual combustion exhaust gas flow rate in the first conduit (5).

3. The method according to claim 2, characterized in that a combustion exhaust gas flow rate difference is determined by comparing the calculated combustion exhaust gas flow rate in the first conduit (5) with the actual combustion exhaust gas flow rate in the first conduit (5), and the determined combustion exhaust gas flow rate difference is used as an input signal to the control unit (33).

4. The method according to claim 2 or 3, characterized in that the generation of the combustion exhaust gas in the combustion space (3) of the first unit (1) is carried out by combustion of a hydrocarbon-containing input material and an oxygen-containing oxidizer via at least one burner (17), and the influencing variable is the flow rate of the oxidizer supplied to the at least one burner (17), and / or the influencing variable is the flow rate of the hydrocarbon-containing input material supplied to the at least one burner.

5. The method according to claim 4, characterized in that the hydrocarbon-containing input material is fuel gas, particularly natural gas, and / or the hydrocarbon-containing input material is off-gas from a pressure swing adsorption unit.

6. The method according to any one of claims 1 to 5, characterized in that a flow rate measurement (10b) is performed in the second conduit (8) downstream of the combustion exhaust gas chimney (4) to measure the actual combustion exhaust gas flow rate in the second conduit (8), and the actual combustion exhaust gas flow rate in the second conduit (8) is used as an input signal (12b) to the control unit.

7. The method according to claim 6, characterized in that the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney (4) is measured based on the difference between the actual combustion exhaust gas flow rate in the first conduit (5) and the actual combustion exhaust gas flow rate in the second conduit (8), and the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney (4) is used as an input signal to the control unit (33).

8. From the aforementioned combustion exhaust gas flow, sulfur oxides (SO4) ｘ The method according to claim 6 or 7, characterized in that a combustion exhaust gas cleaning device (20) for removing (and cooling the combustion exhaust gas flow) is installed in the second conduit (8) and upstream of the second unit (2), and the flow rate measurement (10b) for measuring the actual combustion exhaust gas flow rate in the second conduit (8) is performed upstream of the combustion exhaust gas cleaning device (20).

9. The method according to any one of claims 1 to 8, characterized in that the booster device (9), in particular the blower, includes a rotating element, and the control unit (33) controls the pressure in the first unit (1) by the rotational speed of the rotating element via an output signal.

10. The method according to claim 9, characterized in that a flap element having a variable flow cross-section is arranged in the first conduit (5), and the control unit (33) further controls the pressure in the first unit (1) via an output signal according to the size of the flow cross-section of the flap element.

11. The method according to any one of claims 1 to 10, characterized in that the measurement of the oxygen concentration in the combustion exhaust gas flow is performed in the first conduit (5) and / or the second conduit (8), and the measured oxygen concentration is used as an input signal to the control unit (33).

12. A device for separating carbon dioxide from combustion exhaust gas flow, A first unit (1) generates a carbon dioxide-containing combustion exhaust gas flow within the combustion space (3), A second unit (2) is configured to separate carbon dioxide from the carbon dioxide-containing combustion exhaust gas flow and thus generate a carbon dioxide product flow, A combustion exhaust gas chimney (4) located downstream of the first unit (1) and upstream of the second unit (2), having a combustion exhaust gas inlet (6) and a combustion exhaust gas outlet (7), connected to the first unit (1) via a first conduit (5) and the combustion exhaust gas inlet (6), and connected to the second unit (2) via a second conduit (8) and the combustion exhaust gas outlet (7), A pressurizing device (9), particularly a blower, is located within the first conduit (5) and is configured to draw in combustion exhaust gas from the first unit (1) and maintain a constant pressure within the first unit. In a device equipped with, A flow rate measuring device is placed inside the first conduit (5), and the flow rate measuring device is adapted to measure the actual combustion exhaust gas flow rate inside the first conduit (5). The pressure inside the first unit (1) can be controlled using a control unit (33), and the actual combustion exhaust gas flow rate inside the first conduit (5) can be used as an input signal (12a) to the control unit. A device characterized by the following features.

13. The control unit (33) enables the capture of at least one influencing variable suitable for predicting the calculable combustion exhaust gas flow rate, thereby, Based on the aforementioned at least one influencing variable, the calculated combustion exhaust gas flow rate, which is expected to flow through the first conduit (5) at that flow rate, can be determined. The apparatus according to claim 12, characterized in that the calculated combustion exhaust gas flow rate in the first conduit (5) can be compared with the actual combustion exhaust gas flow rate in the first conduit (5).

14. The apparatus according to claim 13, characterized in that the combustion exhaust gas flow rate difference can be determined by comparing the calculated combustion exhaust gas flow rate in the first conduit (5) with the actual combustion exhaust gas flow rate in the first conduit (5), and the determined combustion exhaust gas flow rate difference can be used as an input signal to the control unit (33).

15. The apparatus according to any one of claims 12 to 14, characterized in that the first unit (1) comprises at least one burner (17) in the combustion space (3), the burner (17) generates the combustion exhaust gas flow by combustion of a hydrocarbon-containing input material and an oxygen-containing oxidizer, the influencing variable is the flow rate of the oxidizer supplied to the at least one burner (17), and / or the influencing variable is the flow rate of the hydrocarbon-containing input material supplied to the at least one burner (17).

16. The apparatus according to any one of claims 12 to 15, characterized in that the hydrocarbon-containing input material is a fuel gas, particularly natural gas, and / or the hydrocarbon-containing input material is an off-gas from a pressure swing adsorption unit.

17. The apparatus according to any one of claims 12 to 16, characterized in that a flow rate measuring device for measuring the actual combustion exhaust gas flow rate in the second conduit (8) is located in the second conduit (8) downstream of the combustion exhaust gas chimney (4), and the actual combustion exhaust gas flow rate in the second conduit (8) can be used as an input signal (12b) to the control unit (33).

18. The apparatus according to claim 17, characterized in that the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney (4) can be determined based on the difference between the actual combustion exhaust gas flow rate in the first conduit (5) and the actual combustion exhaust gas flow rate in the second conduit (8), and the actual combustion exhaust gas flow rate in the combustion exhaust gas chimney (4) can be used as an input signal to the control unit.

19. From the aforementioned combustion exhaust gas flow, sulfur oxides (SO4) ｘ The apparatus according to claim 17 or 18, characterized in that a combustion exhaust gas cleaning device (20) for removing (and cooling the combustion exhaust gas flow) is located inside the second conduit (8) and upstream of the second unit (2), and a flow rate measuring device for measuring the actual combustion exhaust gas flow rate inside the second conduit (8) is located upstream of the combustion exhaust gas cleaning device.

20. The apparatus according to any one of claims 12 to 19, characterized in that the boosting device (9), in particular a blower, includes a rotating element, and the control unit (33) controls the pressure in the first unit (1) by the rotational speed of the rotating element via an output signal (13a).

21. The apparatus according to claim 20, characterized in that a flap element having a variable flow cross-section is arranged in the first conduit (5), and the control unit (33) further controls the pressure in the first unit (1) via an output signal according to the size of the flow cross-section of the flap element.

22. The apparatus according to any one of claims 12 to 21, characterized in that a measuring device for measuring the oxygen concentration in the combustion exhaust gas flow is arranged in the first conduit (5) and / or the second conduit (8), and the measured oxygen concentration can be used as an input signal to the control unit (33).

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