Wooden biomass continuous pyrolysis rate calculation and implantation method based on thermogravimetric experiment

Abstract

The invention discloses a woody biomass continuous pyrolysis rate calculation and implantation method based on thermogravimetric experiments, and belongs to the technical field of energy utilization, the method comprises the following steps: carrying out multiple times of woody biomass thermogravimetric experiments according to a specified heating rate, obtaining a change curve of apparent activation energy E [alpha] along with a conversion rate [alpha] based on Friedman and other conversion methods, according to a continuous curve of the ln value of the product of the prefactor A alpha and the reaction mechanism function f (alpha), calculating the continuous pyrolysis rate through an Arrhenius formula; a piecewise polynomial is used for fitting E alpha-alpha and ln [A alpha * f (alpha)]-alpha, the pyrolysis rate is calculated again based on a fitting formula, calculation fluctuation is corrected, and the last stage of pyrolysis which cannot be calculated is supplemented; a piecewise polynomial is converted into an array form to be implanted, and an Arrhenius formula and a supplementary equation can be directly implanted, so that calculation of the continuous pyrolysis rate of the wood biomass and code implantation are realized. According to the method, a method reference can be provided for pyrolysis rate calculation in the wood biomass combustion process.

Description

Technical Field

[0001] The invention relates to the technical field of energy utilization, and in particular to a method for calculating and implanting the continuous pyrolysis rate of wood biomass based on thermogravimetric experiments. Background Art

[0002] Biofuel refers to liquid, solid or gaseous fuel converted from biomass raw materials. It is a renewable energy source and plays a vital role in zero-carbon plans. Biofuel can come from woody biomass, algae biomass, animal residues or industrial waste. Among them, woody biomass mainly contains hemicellulose, cellulose and lignin, and has the widest range of applications. The prediction of its pyrolysis process is an important means to improve energy utilization efficiency and improve combustion systems. The most important parameter in the pyrolysis prediction process is the pyrolysis rate, which is related to the release rate of the product and the prediction of the degree of pyrolysis, and affects the prediction accuracy.

[0003] Thermogravimetric analysis (TGA) is a method that uses a thermogravimetric analyzer to study the thermal behavior of materials. It can be used for a variety of biofuel quality analyses, including thermal degradation, ignition, burnout, and reactive behavior. TGA can also cover thermochemical process analysis, such as baking, pyrolysis, gasification, and combustion, and different heating rates or heating residence times can be applied to study the thermal degradation behavior of biomass. This technology plays a vital role in promoting the development of recycling flow technology for bio-based materials.

[0004] Pyrolysis of woody biomass involves many decomposition reactions, and its pyrolysis kinetic parameters (apparent activation energy E, prefactor A, etc.) usually change with the conversion rate. Conversion methods such as Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) are commonly used methods to estimate the apparent activation energy of reactions, but there are significant errors in the estimation process, especially in scenarios where the activation energy changes. The frequency factor is usually calculated by the Kissinger method, which requires the assumption that the chemical reaction process conforms to the first-order chemical reaction model and the kinetic parameters are constant, and cannot accurately describe the kinetic behavior of complex reactions. Using the above method may result in large errors in the calculated apparent activation energy and frequency factor, thereby affecting the calculation of thermodynamic parameters.

[0005] There are serious problems in calculating the pyrolysis rate using the above method: the data between the conversion rate sampling intervals cannot be effectively determined; there are obvious errors in calculating the reaction rate using the average activation energy and frequency factor, and the wrong pyrolysis rate will lead to wrong heat release, and there is a possibility that the error will be amplified, thus affecting the calculation prediction accuracy. It can be seen that the above method has obvious limitations, and a more accurate method for solving the continuous pyrolysis rate is urgently needed. Summary of the invention

[0006] The present invention provides a method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments. The conversion rate versus time and temperature curves are obtained through thermogravimetric experiments at different heating rates, and then the apparent activation energy E is obtained through a series of methods. α Curves of changes in conversion rate α and pre-factor A α The curve of the ln value of the product of the reaction mechanism function f(α) and the conversion rate α and the fitting formula can be used to calculate the continuous pyrolysis rate based on the Arrhenius formula. The subsequent code implantation is based on the fitting formula to facilitate numerical calculations, so as to solve the technical problem of low accuracy in the prediction of the pyrolysis rate of wood biomass.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In one aspect, the present invention provides a method for calculating and implanting a continuous pyrolysis rate of woody biomass based on a thermogravimetric experiment, the method comprising:

[0009] Carry out multiple thermogravimetric experiments on woody biomass at a specified heating rate, derive the weight-time and temperature curve of the sample, and obtain the apparent activation energy E based on the Friedman conversion method. α Curves of changes in conversion rate α and pre-factor A α The change curve of the ln value of the product of the reaction mechanism function f(α) with the conversion rate α is used to calculate the pyrolysis rate using the Arrhenius formula to obtain the continuity curve of the pyrolysis rate with the sample conversion rate;

[0010] Using piecewise polynomials for E α -α and ln[A α f(α)]-α is fitted, and the pyrolysis rate is calculated again based on the fitting formula, the calculated fluctuation is corrected, and the late pyrolysis stage that cannot be calculated is supplemented;

[0011] The piecewise polynomial is converted into array form for implantation, and the Arrhenius formula and supplementary equation can be directly implanted, thereby realizing the calculation and code implantation of the continuous pyrolysis rate of wood biomass.

[0012] Furthermore, multiple thermogravimetric experiments of woody biomass are performed at a specified heating rate to derive a curve of the weight of the sample versus time and temperature, including:

[0013] For specific wood biomass, powder is made and dried, and thermogravimetric analysis instruments are used to conduct multiple thermogravimetric experiments at different heating rates. The heating rate is generally set to 5K / min and 10K / min, and nitrogen is used as the atmosphere. The heating range is determined according to the actual application scenario.

[0014] Based on the curve of sample weight versus time and temperature generated by the instrument, the curve of sample conversion rate α versus time and temperature is plotted.

[0015] Furthermore, the sample powder needs to be sieved through a mesh screen, and its particle size is less than 0.18 mm, and only about 3-5 mg is required for a thermogravimetric experiment; a low heating rate, a small sample size, and fine sawdust are selected to reduce the influence of heat transfer on the measurement results.

[0016] Furthermore, the sample conversion rate is the degree of pyrolysis of the sample. When the sample is not pyrolyzed, its conversion rate is 0, and the conversion rate after complete pyrolysis is 1.

[0017] Furthermore, based on the conversion method of Friedman et al., E α -α and ln[A α f(α)]-α continuous curve, the pyrolysis rate is calculated by Arrhenius formula, and the continuity curve of pyrolysis rate with sample conversion rate is obtained, including:

[0018] Based on the thermogravimetric experimental data, the apparent activation energy E of thermal decomposition can be solved by the Friedman conversion method. α , and the frequency factor A α and the ln value of the product of the mechanism function f(α), that is, ln[A α ·f(α)]-α, thus obtaining E α -α and ln[A α f(α)]-α curve;

[0019] Based on the acquisition of E α -α and ln[A α f(α)]-α curve, through the Arrhenius formula dα / dt=Ae -α / R·T f(α)=e^{ln[A α ·f(α)]-E α / (R·T α,i )} to calculate the conversion rate dα / dt. The pyrolysis rate can be obtained by multiplying the conversion rate by the sample mass, thereby obtaining a continuity curve of the pyrolysis rate versus the sample conversion rate.

[0020] Furthermore, the Friedman et al. transformation method is a data processing method, and the specific method is:

[0021] Substitute the heating rate β = dT / dt into the Arrhenius formula dα / dt = Ae -E / R·T f(α), we get ln[β i (dα / dt) α,i ]=ln[A α ·f(α)]-Eα / (R·T α,i ), where R is the ideal gas constant, T α,i is the temperature at different heating rates i and different conversion rates α;

[0022] Obtain the data of ln(β·dα / dT) and -1000 / (RT) at different heating rates i and the same conversion rate α, connect two points with the same conversion rate and calculate the slope and intercept of the straight line;

[0023] The slope of the straight line is the apparent activation energy of pyrolysis E α , the intercept is ln[A α ·f(α)]-α.

[0024] Furthermore, using piecewise polynomials for E α -α and ln[A α f(α)]-α is fitted, and the pyrolysis rate is calculated again based on the fitting formula to correct the calculation fluctuations, including:

[0025] For E α -α and ln[A α The f(α)]-α curves were fitted with piecewise polynomials to obtain fitting formulas, and the fitting formulas were substituted into the Arrhenius formula to obtain the dα / dt-α curves;

[0026] Based on the linear form of the Arrhenius formula ln[A α ·f(α)]-E α / (R·T α,i )=ln(dα / dt) to correct the curve fluctuation. The specific method is to set the ln(dα / dt) values ​​of two different heating rates as C1 and C2 at the same conversion rate, and obtain E α =(C1-C2) / [1 / (R·T α,2 )–1 / (R·T α,1 )],ln[A α f(α)]=C1+E α / (R·T α,1 );

[0027] Fit the ln(dα / dt)-α curve and T-α curve under different conversion rates, and substitute the fitting formula into the above formula to solve E α andln[A α ·f(α)], thereby correcting the conversion rate data in the fluctuation area.

[0028] Furthermore, the segmented fitting method is prone to data differences at the endpoints of the segments, resulting in certain fluctuations in the recalculated dα / dt-α curve.

[0029] Furthermore, the final stage of pyrolysis that cannot be calculated is supplemented, including:

[0030] At the end of the pyrolysis stage, dα / dt=(dα / dT)·(dT / dt) is used to calculate the conversion rate. The specific method is to solve dα / dT based on the data of thermogravimetric changes with temperature, and perform segmented simplification processing to sort out the simplified linear fitting formula, and then solve dT / dt based on the data of temperature changes with time, so as to calculate the pyrolysis rate at the end of the pyrolysis stage.

[0031] Furthermore, the piecewise polynomial fitting method cannot be used in the late stage of pyrolysis: E α andln[A α ·f(α)] becomes negative after the conversion rate reaches a certain value. The data difference is large, and the segmented fitting method cannot fit the data of the subsequent stage, resulting in the inability to calculate the pyrolysis rate of this stage.

[0032] Furthermore, the piecewise polynomial is converted into an array form for implantation. The Arrhenius formula and supplementary equations can be directly implanted, including:

[0033] Arrange the coefficients of the piecewise polynomial into an array, and convert a large amount of experimental data into an array of polynomial coefficients to facilitate code implantation and correction;

[0034] The Arrhenius formula and supplementary equations do not rely on experimental data and can be directly implanted.

[0035] Based on the results of thermogravimetric experiments on woody biomass, the present invention proposes a continuity curve calculation method for the ln value of the product of the apparent activation energy, the prefactor and the mechanism function that changes with the conversion rate, and a piecewise polynomial fitting method for the curve, which can calculate the continuous pyrolysis rate that changes with the conversion rate. After the fitting formula is implanted, the calculation is convenient, thereby providing a reference for the prediction of the pyrolysis process of woody biomass.

[0036] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects:

[0037] 1. The general calculation methods of wood biomass pyrolysis rate use the average apparent activation energy and pre-factor to describe the pyrolysis reaction kinetics. The present invention obtains the data of wood biomass thermogravimetric changes with time and temperature based on thermogravimetric experiments, and then obtains the continuous E through the Friedman conversion method and Arrhenius formula. α -α and ln[A α f(α)]-α curve, with a higher sampling rate, provides a more accurate data basis for calculating the pyrolysis rate.

[0038] 2. The present invention adopts E α -α and ln[A α ·f(α)]-α curve is fitted and corrected by piecewise polynomial, and a coefficient array is obtained for convenient code implantation, which avoids the need to process a large amount of experimental data in the calculation process and improves the calculation efficiency. The present invention also provides an effective calculation and implantation method for the pyrolysis rate calculation in the late stage of pyrolysis, which can provide an important methodological basis for the prediction of the whole process of wood biomass pyrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 It is a schematic diagram of the execution flow of the method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments provided in an embodiment of the present invention;

[0041] Figure 2 TG and DTG curves of a Finnish pine sample generated by a thermogravimetric analyzer provided in an embodiment of the present invention;

[0042] Figure 3 It is a curve of conversion rate α and dα / dT versus temperature calculated based on TG and DTG data of Finnish pine wood samples provided in an embodiment of the present invention;

[0043] Figure 4 are ln(β·dα / dT) and -1000 / (RT) data at different heating rates i and the same conversion rate α provided in the embodiments of the present invention;

[0044] Figure 5 is a calculation curve of the conversion rate dα / dt provided in an embodiment of the present invention;

[0045] Figure 6 is a conversion rate dα / dt curve calculated based on a fitting formula provided in an embodiment of the present invention;

[0046] Figure 7 It is the conversion rate dα / dt curve after correction and supplementation provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0048] First of all, it should be noted that in the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "exemplarily" is intended to present the concept in a concrete way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0049] Moreover, in the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they want to express are the same. "of", "corresponding, relevant" and "corresponding" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they want to express are the same.

[0050] In addition, in the embodiments of the present invention, sometimes a subscript (such as W1) may be mistakenly written as a non-subscript form (such as W1). When the difference is not emphasized, the meanings to be expressed are consistent.

[0051] Example

[0052] This embodiment provides a method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments. The method can be implemented by an electronic device, which can be a terminal or a server. The execution flow of the method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments is shown in the figure, and includes:

[0053] S1, perform multiple thermogravimetric experiments on woody biomass at a specified heating rate, and derive the weight-versus-time and temperature curves of the samples;

[0054] Specifically, in this embodiment, the implementation process of the above S1 is as follows:

[0055] S11, preparing powder and drying specific woody biomass;

[0056] Among them, the sample powder needs to be sieved through a mesh screen, and its particle size is less than 0.18mm, and only about 3-5mg is required for a thermogravimetric experiment;

[0057] S12, using a thermogravimetric analyzer to conduct multiple thermogravimetric experiments at different heating rates. The heating rate is generally set to 5K / min and 10K / min. The atmosphere uses nitrogen. The heating range is determined according to the actual application scenario.

[0058] Among them, low heating rate, small sample size, and fine sawdust were chosen to reduce the influence of heat transfer on the measurement results;

[0059] S13, based on the curve of sample weight versus time and temperature generated by the instrument, plotting the curve of sample conversion rate α versus time and temperature.

[0060] S2, Obtaining Apparent Activation Energy E Based on Friedman and Other Conversion Methods α Curves of changes in conversion rate α and pre-factor A α The change curve of the ln value of the product of the reaction mechanism function f(α) with the conversion rate α is used to calculate the pyrolysis rate using the Arrhenius formula to obtain the continuity curve of the pyrolysis rate with the sample conversion rate;

[0061] Specifically, in this embodiment, the implementation process of the above S2 is as follows:

[0062] S21, based on the thermogravimetric experimental data, the apparent activation energy E of thermal decomposition can be solved by the Friedman conversion method. α , and the frequency factor A α and the ln value of the product of the mechanism function f(α), that is, ln[A α ·f(α)]-α, thus obtaining E α -α and ln[A α f(α)]-α curve;

[0063] Among them, the Friedman et al. transformation method is a data processing method, and the specific method is:

[0064] Substitute the heating rate β = dT / dt into the Arrhenius formula dα / dt = Ae -E / R·T f(α), we get ln[β i (dα / dt) α,i ]=ln[A α ·f(α)]-E α / (R·T α,i ), where R is the ideal gas constant, T α,i is the temperature at different heating rates i and different conversion rates α;

[0065] Obtain the data of ln(β·dα / dT) and -1000 / (RT) at different heating rates i and the same conversion rate α, connect two points with the same conversion rate and calculate the slope and intercept of the straight line;

[0066] The slope of the straight line is the apparent activation energy of pyrolysis E α , the intercept is ln[A α ·f(α)]-α.

[0067] S22, based on the acquired E α -α and ln[A αf(α)]-α curve, through the Arrhenius formula dα / dt=Ae -α / R·T f(α)=e^{ln[A α ·f(α)]-E α / (R·T α,i )} to calculate the conversion rate dα / dt. The pyrolysis rate can be obtained by multiplying the conversion rate by the sample mass, thereby obtaining a continuity curve of the pyrolysis rate versus the sample conversion rate.

[0068] S3, using piecewise polynomials for E α -α and ln[A α f(α)]-α is fitted, and the pyrolysis rate is calculated again based on the fitting formula to correct the calculation fluctuation;

[0069] Specifically, in this embodiment, the implementation process of the above S3 is as follows:

[0070] S31, to E α -α and ln[A α The f(α)]-α curves were fitted with piecewise polynomials to obtain fitting formulas, and the fitting formulas were substituted into the Arrhenius formula to obtain the dα / dt-α curves;

[0071] S32, based on the linear form of the Arrhenius formula ln[A α ·f(α)]-E α / (R·T α,i )=ln(dα / dt) to correct the curve fluctuation. The specific method is to set the ln(dα / dt) values ​​of two different heating rates as C1 and C2 at the same conversion rate, and obtain E α =(C1-C2) / [1 / (R·T α,2 )–1 / (R·T α,1 )],ln[A α f(α)]=C1+E α / (R·T α,1 );

[0072] S33, fitting ln(dα / dt)-α curve and T-α curve under different conversion rates, and substituting the fitting formula into the above formula to solve E α andln[A α ·f(α)], thereby correcting the conversion rate data in the fluctuation area.

[0073] S4, supplements the uncalculated final stage of pyrolysis;

[0074] Specifically, in this embodiment, the implementation process of the above S4 is as follows:

[0075] S41, at the end of the pyrolysis stage, the conversion rate is calculated using dα / dt=(dα / dT)·(dT / dt), and the specific method is to solve dα / dT based on the thermogravimetric data of temperature change, and perform piecewise simplification processing to sort out a simplified linear fitting formula;

[0076] Among them, the piecewise polynomial fitting method cannot be used in the late stage of pyrolysis: E α andln[A α ·f(α)] becomes negative after the conversion rate reaches a certain value. The data difference is large, and the segmented fitting method cannot fit the data of the subsequent stage, resulting in the inability to calculate the pyrolysis rate of this stage.

[0077] S42, solving dT / dt based on the temperature variation data over time, thereby calculating the pyrolysis rate at the end stage of pyrolysis.

[0078] S5, the piecewise polynomial is converted into array form for implantation, and the Arrhenius formula and supplementary equation can be directly implanted.

[0079] Specifically, in this embodiment, the implementation process of the above S5 is as follows:

[0080] S51, organize the coefficients of the piecewise polynomial into an array form, convert a large amount of experimental data into an array composed of polynomial coefficients, so as to facilitate code implantation and correction;

[0081] S52, Arrhenius formula and supplementary equations do not need to rely on experimental data and can be directly implanted.

[0082] Below, this embodiment uses a practical application scenario to illustrate the application process of the method of the present invention.

[0083] This example uses Finnish pine as the research object, and performs continuous pyrolysis rate calculation and implantation of Finnish pine based on thermogravimetric experiment. The initial thermogravimetric temperature of this example is 14°C, and the termination temperature of the thermogravimetric experiment is 800°C. Based on this, the specific implementation process of the method of the present invention is as follows:

[0084] (1) Making Finnish pine samples

[0085] Among them, about 4.5 mg of dried Finnish pine wood sample was prepared and sieved through an 80-mesh sieve, and the particle size thereof was less than 0.18 mm.

[0086] The apparent density of the Finnish pine wood sample used is 491.4 kg / m 3 .

[0087] (2) Conduct thermogravimetric analysis experiments on Finnish pine wood and derive experimental data.

[0088] Among them, the thermogravimetric analysis experiment is completed by a thermogravimetric analyzer, which is mainly composed of a temperature-controlled furnace, a crucible and a crucible support, and a high-precision thermal balance connected to the crucible support.

[0089] The heating rates were set to 5K / min and 10K / min, respectively, the atmosphere was N2, and the flow rate was 30mL / min.

[0090] During the experiment, the specified gas will be introduced into the equipment, and the sample will be heated according to the specified time-temperature program in this atmosphere. During the heating process, the balance will monitor the sample mass data, and the thermocouple will record the temperature data, so as to obtain the mass loss data of the sample over time or temperature, and obtain the TG and DTG curves, such as Figure 2 shown.

[0091] (3) Plot the sample conversion rate α versus time and temperature curve.

[0092] The curve generated by the instrument is actually composed of dense data points, and there are sampling intervals between the data points.

[0093] When generating the sample conversion rate α versus time and temperature curve based on the original curve, mathematical operations are performed based on the data point data.

[0094] The conversion rate corresponding to the initial mass of the sample is defined as 0, and the lost mass divided by the initial mass is the conversion rate. The calculated data points are plotted in the form of a curve to obtain the curve of the sample conversion rate α changing with time and temperature, such as Figure 3 shown.

[0095] (4) Get E α -α and ln[A α ·f(α)]-α curve.

[0096] Based on the thermogravimetric experimental data, the apparent activation energy E of thermal decomposition was solved by the Friedman conversion method. α , and the frequency factor A α and the ln value of the product of the mechanism function f(α), that is, ln[A α ·f(α)]-α;

[0097] Among them, the Friedman et al. transformation method is a data processing method, and the specific method is:

[0098] Substitute the heating rate β = dT / dt into the Arrhenius formula dα / dt = Ae -E / R·T f(α), we get ln[β i (dα / dt) α,i ]=ln[A α ·f(α)]-E α / (R·Tα,i ), where R is the ideal gas constant, T α,i is the temperature at different heating rates i and different conversion rates α;

[0099] Obtain the data of ln(β·dα / dT) and -1000 / (RT) at different heating rates i and the same conversion rate α, connect two points with the same conversion rate and calculate the slope and intercept of the straight line; the slope of the straight line is the apparent activation energy of pyrolysis E α , the intercept is ln[A α ·f(α)]-α, such as Figure 4 shown.

[0100] (5) Obtain the continuity curve of pyrolysis rate versus sample conversion rate.

[0101] Based on the acquisition of E α -α and ln[A α f(α)]-α curve, through the Arrhenius formula dα / dt=Ae -α / R·T f(α)=e^{ln[A α ·f(α)]-E α / (R·T α,i )} to calculate the conversion rate dα / dt, such as Figure 5 As shown; the pyrolysis rate is obtained by multiplying the conversion rate by the sample mass, and a continuity curve of the pyrolysis rate versus the sample conversion rate is obtained.

[0102] (6) Fitting E α -α and ln[A α ·f(α)]-α curve.

[0103] Among them, α -α and ln[A α f(α)]-α curves are fitted with piecewise polynomials to obtain fitting formulas;

[0104] Substituting the fitting formula into the Arrhenius formula to obtain the dα / dt-α curve, we get Figure 6 ;

[0105] (7) Correct the curve fluctuation.

[0106] Convert the Arrhenius formula to linear form ln[A α ·f(α)]-E α / (R·T α,i ) = ln(dα / dt);

[0107] At the same conversion rate, let the ln(dα / dt) values ​​of two different heating rates be C1 and C2, and we get E α=(C1-C2) / [1 / (R·T α,2 )–1 / (R·T α,1 )],ln[A α f(α)]=C1+E α / (R·T α,1 );

[0108] Fitting ln(dα / dt)-α curve and T-α curve under different conversion rates;

[0109] Substitute the fitting formula into the above formula and solve for E α andln[A α ·f(α)], thereby correcting the conversion rate data in the fluctuation area.

[0110] (8) Supplement the calculation of pyrolysis rate and curve fitting method in the final stage of pyrolysis.

[0111] At the end of the pyrolysis stage, the conversion rate was calculated using dα / dt=(dα / dT)·(dT / dt);

[0112] The specific method is to first solve dα / dT based on the thermogravimetric data of temperature change;

[0113] Perform piecewise simplification processing and sort out the simplified linear fitting formula;

[0114] Based on the temperature-time variation data, dT / dt is solved to calculate the pyrolysis rate at the end of the pyrolysis period. The corrected and supplemented curve is as follows: Figure 7 shown.

[0115] (9) Implantation operation.

[0116] Arrange the coefficients of the piecewise polynomial into an array, and convert a large amount of experimental data into an array of polynomial coefficients to facilitate code implantation and correction;

[0117] The Arrhenius formula and supplementary equations do not rely on experimental data and can be directly implanted.

[0118] In summary, this embodiment provides a method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments. The conversion rate versus time and temperature curves are obtained through thermogravimetric experiments at different heating rates, and then the apparent activation energy E is obtained through a series of methods. α Curves of changes in conversion rate α and pre-factor A α The curve of the ln value of the product of the reaction mechanism function f(α) and the fitting formula with the conversion rate α can be used to calculate the continuous pyrolysis rate of Finnish pine based on the Arrhenius formula. Subsequent code implantation is based on the fitting formula, which facilitates numerical calculations and improves the prediction accuracy of the pyrolysis process.

[0119] Finally, it should be noted that the above is a preferred embodiment of the present invention. It should be noted that although the basic creative concept of the present invention has been described, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. Therefore, the attached claims are intended to be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the embodiments of the present invention.

Claims

1. A method for calculating and implementing the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments, characterized in that: The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments includes: Carry out multiple thermogravimetric experiments on woody biomass at a specified heating rate, and derive the curve of the weight change of the sample over time and temperature; Obtaining the apparent activation energy E based on Friedman et al. conversion method α Curves of changes in conversion rate α and pre-factor A α The change curve of the ln value of the product of the reaction mechanism function f(α) with the conversion rate α is used to calculate the pyrolysis rate using the Arrhenius formula to obtain the continuity curve of the pyrolysis rate with the sample conversion rate; Using piecewise polynomials for E α -α and ln[A α f(α)]-α is fitted, and the pyrolysis rate is calculated again based on the fitting formula, the calculated fluctuation is corrected, and the late pyrolysis stage that cannot be calculated is supplemented; The piecewise polynomials are converted into array form for implantation, and the Arrhenius formula, correction and supplementary equations can be directly implanted, thereby realizing the calculation and code implantation of the continuous pyrolysis rate of wood biomass.

2. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 1, characterized in that: Perform multiple thermogravimetric experiments on woody biomass at a specified heating rate and derive the weight-over-time and temperature curves of the samples, including: For specific wood biomass, powder is made and dried, and thermogravimetric analysis instruments are used to conduct multiple thermogravimetric experiments at different heating rates. The heating rate is generally set to 5K / min and 10K / min, and nitrogen is used as the atmosphere. The heating range is determined according to the actual application scenario. Based on the curve of sample weight versus time and temperature generated by the instrument, the curve of sample conversion rate α versus time and temperature is plotted.

3. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 2, characterized in that: The characteristics of the samples are: The sample powder needs to be sieved through a mesh screen, and its particle size is less than 0.18mm, and only about 3-5mg is required for one thermogravimetric experiment; A low heating rate, a small sample size, and fine wood chips were chosen to reduce the effects of heat transfer on the measurement results.

4. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 2, characterized in that: The sample conversion rate is the degree of pyrolysis of the sample. When the sample is not pyrolyzed, its conversion rate is 0, and the conversion rate after complete pyrolysis is 1.

5. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 1, characterized in that: Based on the conversion method of Friedman et al., the apparent activation energy E is obtained based on the conversion method of Friedman et al. α Curves of changes in conversion rate α and pre-factor A α The curve of the ln value of the product of the reaction mechanism function f(α) and the conversion rate α is used to calculate the pyrolysis rate using the Arrhenius formula to obtain the continuity curve of the pyrolysis rate versus the sample conversion rate, including: Based on the thermogravimetric experimental data, the apparent activation energy E of thermal decomposition can be solved by the Friedman conversion method. α , and the frequency factor A α and the ln value of the product of the mechanism function f(α), that is, ln[A α ·f(α)]-α, thus obtaining E α -α and ln[A α f(α)]-α curve; Based on the acquisition of E α -α and ln[A α f(α)]-α curve, through the Arrhenius formula dα / dt=Ae -α / R·T f(α)=e^{ln[A α ·f(α)]-E α / (R·T α,i )} to calculate the conversion rate dα / dt. The pyrolysis rate can be obtained by multiplying the conversion rate by the sample mass, thereby obtaining a continuity curve of the pyrolysis rate versus the sample conversion rate.

6. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 5, characterized in that: Friedman et al. conversion method is a data processing method, the specific method is: Substitute the heating rate β = dT / dt into the Arrhenius formula dα / dt = Ae -E / R·T f(α), we get ln[β i (dα / dt) α,i ]=ln[A α ·f(α)]-E α / (R·T α,i ), where R is the ideal gas constant, T α,i is the temperature at different heating rates i and different conversion rates α; Obtain the data of ln(β·dα / dT) and -1000 / (RT) at different heating rates i and the same conversion rate α, connect two points with the same conversion rate and calculate the slope and intercept of the straight line; The slope of the straight line is the apparent activation energy of pyrolysis E α , the intercept is ln[A α ·f(α)]-α.

7. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 1, characterized in that: Using piecewise polynomials for E α -α and ln[A α f(α)]-α is fitted, and the pyrolysis rate is calculated again based on the fitting formula to correct the calculation fluctuations, including: For E α -α and ln[A α The f(α)]-α curves were fitted with piecewise polynomials to obtain fitting formulas, and the fitting formulas were substituted into the Arrhenius formula to obtain the dα / dt-α curves; Based on the linear form of the Arrhenius formula ln[A α ·f(α)]-E α / (R·T α,i )=ln(dα / dt) to correct the curve fluctuation. The specific method is to set the ln(dα / dt) values ​​of two different heating rates as C1 and C2 at the same conversion rate, and obtain E α =(C1-C2) / [1 / (R·T α,2 )–1 / (R·T α,1 )],ln[A α f(α)]=C1+E α / (R·T α,1 ); Fit the ln(dα / dt)-α curve and T-α curve under different conversion rates, and substitute the fitting formula into the above formula to solve E α andln[A α ·f(α)], thereby correcting the conversion rate data in the fluctuation area.

8. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 7, characterized in that: The segmented fitting method is prone to data differences at the endpoints of the segments, resulting in certain fluctuations in the recalculated dα / dt-α curve.

9. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 1, characterized in that: Supplement the uncalculated final stage of pyrolysis, including: At the end of the pyrolysis stage, dα / dt=(dα / dT)·(dT / dt) is used to calculate the conversion rate. The specific method is to solve dα / dT based on the data of thermogravimetric changes with temperature, and perform segmented simplification processing to sort out the simplified linear fitting formula, and then solve dT / dt based on the data of temperature changes with time, so as to calculate the pyrolysis rate at the end of the pyrolysis stage.

10. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 9, characterized in that: The piecewise polynomial fitting method cannot be used in the late stage of pyrolysis: E α andln[A α ·f(α)] becomes negative after the conversion rate reaches a certain value. The data difference is large, and the segmented fitting method cannot fit the data of the subsequent stage, resulting in the inability to calculate the pyrolysis rate of this stage.

11. The method for calculating and implanting the continuous pyrolysis rate of woody biomass based on thermogravimetric experiments according to claim 1, characterized in that: The piecewise polynomial is converted into an array form for implantation. The Arrhenius formula and supplementary equations can be directly implanted, including: Arrange the coefficients of the piecewise polynomial into an array, and convert a large amount of experimental data into an array of polynomial coefficients to facilitate code implantation and correction; The Arrhenius formula and supplementary equations do not rely on experimental data and can be directly implanted.

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