Wooden biomass water evaporation rate calculation and precision improvement method based on thermogravimetric experiment

Abstract

The invention discloses a woody biomass water evaporation rate calculation and precision improvement 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 in a water evaporation temperature interval according to different heating rates, taking a water evaporation process as a chemical reaction process, and taking the chemical reaction process as a water evaporation temperature interval; the average apparent activation energy E at different heating rates and the ln value of the prefactor A are solved on the basis of a thermogravimetric curve, and then preliminary calculation of the water evaporation rates at different heating rates is conducted through an Arrhenius formula; respectively introducing correction coefficients cE and cA into E and lnA in a water evaporation rate preliminary calculation formula under each heating rate, solving the correction coefficients by using a Nelder-Mead algorithm, and establishing a function relationship between the correction coefficients and the heating rates; the coefficient in the function relation is solved through the Nelder-Mead algorithm again, secondary correction is carried out, the calculation precision of the water evaporation rate can be improved, and therefore calculation and precision improvement of the water evaporation rate of the wood biomass are achieved. According to the method, a method reference can be provided for calculating the water evaporation rate in the heating and combustion processes of the wood biomass.

Description

Technical Field

[0001] The invention relates to the technical field of energy utilization, and in particular to a method for calculating and improving the evaporation rate of wood biomass water based on a thermogravimetric experiment. Background Art

[0002] As a renewable resource, woody biomass has broad application prospects in the field of energy utilization. In the heating and combustion process of woody biomass, water evaporation is a key link, and its rate directly affects the combustion efficiency and energy utilization efficiency. However, the current calculation method of the water evaporation rate of woody biomass has the problem of insufficient accuracy, especially under different heating rates and temperature conditions, the existing methods are difficult to accurately predict the water evaporation rate. Therefore, the development of a high-precision water evaporation rate calculation method is of great significance for optimizing the energy utilization process of woody biomass. Summary of the invention

[0003] The present invention provides a method for calculating and improving the water evaporation rate of wood biomass based on thermogravimetric experiments. Through multiple thermogravimetric experiments and mathematical modeling, high-precision calculation of the water evaporation rate of wood biomass is achieved. The present invention can provide a method reference for calculating the water evaporation rate during the heating and combustion of wood biomass.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] In one aspect, the present invention provides a method for calculating and improving the evaporation rate of wood biomass water based on thermogravimetric experiments, the method comprising:

[0006] Multiple thermogravimetric experiments on woody biomass were conducted in the water evaporation temperature range at different heating rates;

[0007] The water evaporation process is regarded as a chemical reaction process, and the average apparent activation energy E and the ln value of the prefactor A at different heating rates are solved based on the thermogravimetric curve.

[0008] The Arrhenius formula was used to preliminarily calculate the water evaporation rate at different heating rates;

[0009] Correction coefficients were introduced into E and lnA in the preliminary calculation formula of water evaporation rate at each heating rate, and the correction coefficients were solved using the Nelder-Mead algorithm to establish the functional relationship between the correction coefficients and the heating rate.

[0010] The coefficients in the functional relationship are solved again using the Nelder-Mead algorithm, and a secondary correction is performed to improve the calculation accuracy of the water evaporation rate, thereby achieving the calculation and accuracy improvement of the water evaporation rate of wood biomass.

[0011] Further, the thermogravimetric experiment is performed at different heating rates, including:

[0012] Select representative woody biomass samples to ensure that their physical properties such as type, moisture content, density, etc. meet the research requirements;

[0013] A high-precision thermogravimetric analyzer was used to perform a programmed temperature experiment on wood biomass samples, and the mass change data of the samples at different heating rates were recorded;

[0014] Determine the water evaporation temperature range and ensure that the experiment covers the key temperature points within this range.

[0015] Furthermore, the method of solving the ln value of the average apparent activation energy E and the pre-factor A based on the thermogravimetric curve includes:

[0016] Analyze the thermogravimetric curves at different heating rates to extract key parameters in the water evaporation process, such as the starting evaporation temperature, the temperature of the maximum weight loss rate, etc.

[0017] The KAS method is used to solve the ln value of the average apparent activation energy E and the prefactor A.

[0018] Furthermore, the preliminary calculation by the Arrhenius formula includes:

[0019] Substitute the obtained average apparent activation energy E and the ln value of the prefactor A into the Arrhenius formula;

[0020] Calculate preliminary values ​​of water evaporation rate of woody biomass at different heating rates.

[0021] Furthermore, the establishing of the correction formula and solving the correction coefficient include:

[0022] Introduce correction coefficients c into E and lnA in the preliminary calculation formula of water evaporation rate at each heating rate E and c A ;

[0023] The formula is as follows: F=(f cal -f exp ) 2

[0024] Among them, f cal is the calculation result, w moi is the water content of the sample, Δt is the time step, c A and c E are the correction coefficients of E and lnA, respectively, exp are experimental measured values.

[0025] The Nelder-Mead algorithm is used to solve the minimum value of the above formula to solve the correction coefficient;

[0026] Further, establishing a functional relationship between the correction coefficient and the heating rate includes:

[0027] Analyze the variation of correction coefficient under different heating rates;

[0028] The mathematical function relationship between the correction coefficient and the heating rate is established as follows:

[0029] Furthermore, the secondary correction comprises:

[0030] Substitute the mathematical function relationship between the above correction factor and the heating rate into the following calculation formula: F=∑(f cal,i -f exp,i ) 2

[0031] Among them, f cal,i and f exp,i are the calculated and experimental results at different heating rates, w moi,i The water content of the sample at different heating rates Quantity, Δt i is the time step at different heating rates, T i Temperature data at different heating rates. ;

[0032] The Nelder-Mead algorithm is used again to calculate the minimum value of the above formula to solve the coefficients in the functional relationship;

[0033] Through secondary correction, the accuracy of water evaporation rate calculation is further improved.

[0034] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects:

[0035] 1. Through multiple thermogravimetric experiments and mathematical modeling, the present invention can accurately calculate the water evaporation rate of wood biomass at different heating rates, overcoming the shortcomings of existing methods in terms of accuracy.

[0036] 2. The present invention adopts the Nelder-Mead algorithm to optimize and solve the coefficients in the correction formula and the functional relationship, and further improves the calculation accuracy through secondary correction, thereby ensuring the reliability of the results.

[0037] 3. The method of the present invention has strong flexibility and scalability, can be adjusted and optimized according to different wood biomass types and experimental conditions, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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.

[0039] Figure 1 It is a schematic diagram of the execution flow of a method for calculating the evaporation rate of wood biomass water and improving its accuracy based on a thermogravimetric experiment provided in an embodiment of the present invention;

[0040] Figure 2 are the E and lnA data at different heating rates provided by the embodiments of the present invention;

[0041] Figure 3 is c at different heating rates provided by the embodiments of the present invention E and c A data;

[0042] Figure 4 It is a comparison chart of experimental data and calculation results provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0043] 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.

[0044] 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.

[0045] 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.

[0046] In addition, in the embodiments of the present invention, sometimes the subscript (such as W 1 ) may be mistakenly written as a non-subscript form (such as W1). When the difference is not emphasized, the meanings they express are the same.

[0047] Example

[0048] This embodiment provides a method for calculating the evaporation rate of wood biomass water and improving its accuracy based on thermogravimetric experiments. The method can be implemented by an electronic device, which can be a terminal or a server. The execution process of the method for calculating the evaporation rate of wood biomass water and improving its accuracy based on thermogravimetric experiments is as follows: Figure 1 As shown, including:

[0049] S1, multiple thermogravimetric experiments of wood biomass were carried out in the water evaporation temperature range at different heating rates;

[0050] Specifically, in this embodiment, the implementation process of the above S1 is as follows:

[0051] S11, select representative woody biomass samples to ensure that their physical properties such as type, moisture content, density, etc. meet the research requirements;

[0052] S12, using a high-precision thermogravimetric analyzer to perform a programmed temperature experiment on the wood biomass sample, and record the mass change data of the sample at different heating rates;

[0053] S13, determine the water evaporation temperature range and ensure that the experiment covers the key temperature points within the range.

[0054] S2, the water evaporation process is regarded as a chemical reaction process, and the average apparent activation energy E at different heating rates and the ln value of the prefactor A are solved based on the thermogravimetric curve;

[0055] Specifically, in this embodiment, the implementation process of the above S2 is as follows:

[0056] S21, analyze the thermogravimetric curves at different heating rates to extract key parameters in the water evaporation process, such as the starting evaporation temperature, the maximum weight loss rate temperature, etc.;

[0057] S22, the KAS method is used to solve the ln value of the average apparent activation energy E and the prefactor A.

[0058] S3, preliminary calculation of water evaporation rate at different heating rates using the Arrhenius formula;

[0059] Specifically, in this embodiment, the implementation process of the above S3 is as follows:

[0060] S31, substitute the obtained average apparent activation energy E and the ln value of the prefactor A into the Arrhenius formula;

[0061] S32, calculating preliminary values ​​of water evaporation rates of woody biomass at different heating rates.

[0062] S4, introduce correction coefficients c into E and lnA in the preliminary calculation formula of water evaporation rate at each heating rate. A and c E , use the Nelder-Mead algorithm to solve the correction coefficient;

[0063] Specifically, in this embodiment, the implementation process of the above S4 is as follows:

[0064] S41, introduce correction coefficients c into E and lnA in the preliminary calculation formula of water evaporation rate at each heating rate. A and c E ;

[0065] S42, use the Nelder-Mead algorithm to solve the correction factor in the following formula: F=(f cal -f exp ) 2

[0066] Among them, f cal is the calculation result, w moi is the water content of the sample, Δt is the time step, c A and c E are the correction coefficients of E and lnA, respectively, exp are experimental measured values.

[0067] S5, establish the functional relationship between the correction coefficient and the heating rate, and solve the coefficients in the functional relationship again by the Nelder-Mead algorithm. Perform secondary correction to improve the calculation accuracy of water evaporation rate;

[0068] Specifically, in this embodiment, the implementation process of the above S5 is as follows:

[0069] S51, analyze the variation of correction coefficient under different heating rates;

[0070] S52, establish the mathematical function relationship between the correction coefficient and the heating rate as follows:

[0071]

[0072] S53, substituting the mathematical function relationship between the correction coefficient and the heating rate into the following calculation formula: F=∑(f cal,i -f exp,i ) 2

[0073] Among them, f cal,i and f exp,i are the calculated and experimental results at different heating rates, w moi,i The water content of the sample at different heating rates Quantity, Δt i is the time step at different heating rates, T i is the temperature data under different heating rates;

[0074] S54, use the Nelder-Mead algorithm again to calculate the minimum value of the above formula, and solve the coefficients in the function relationship and use it again The Nelder-Mead algorithm solves the coefficients in the functional relationship;

[0075] Through secondary correction, the accuracy of water evaporation rate calculation is further improved.

[0076] Below, this embodiment uses a practical application scenario to illustrate the application process of the method of the present invention.

[0077] In this example, pine wood was used as the wood biomass sample to calculate the water evaporation rate based on the thermogravimetric experiment and reproduce the accuracy improvement process. The experimental environment temperature of this example was 20°C, and a high-precision thermogravimetric analyzer was used to perform a programmed temperature increase experiment on the pine wood sample. The heating rates were set to 5K / min, 10K / min, 15K / min and 20K / min, respectively, and a N flow rate of 30mL / min was used. 2 atmosphere. Therefore, the specific implementation process of the method of the present invention is as follows:

[0078] (1) Thermogravimetric test of pine wood.

[0079] A high-precision thermogravimetric analyzer was used to perform a programmed temperature experiment on the pine wood samples. The temperature range was from room temperature to 100°C, and the heating rates were The settings were 5K / min and 10K / min, using a N2 atmosphere with a flow rate of 30mL / min;

[0080] The mass change data of pine wood samples at different heating rates were recorded in detail, including key parameters such as the starting evaporation temperature and the maximum weight loss rate temperature. The thermogravimetric data were analyzed in depth to extract the main data characteristics of the water evaporation process, such as the shape of the thermogravimetric curve, the changing trend of the weight loss rate, etc. The experimental data were converted into a relationship curve between the mass change rate and the temperature and time.

[0081] (2) Solve the ln value of the average apparent activation energy E and the prefactor A and perform preliminary calculations.

[0082] Based on the Arrhenius formula, the water evaporation rate was preliminarily calculated for the thermogravimetric experimental data, and the ln value of the average apparent activation energy E and the prefactor A were solved respectively (such as Figure 2 As shown), a preliminary formula for calculating the water evaporation rate was obtained.

[0083] (3) Introduce the correction coefficient and solve it.

[0084] The correction coefficient is introduced into the preliminary calculation formula of water evaporation rate at each heating rate, and the values ​​of E and lnA are corrected respectively. The following formula is established and the correction coefficient is solved using the Nelder-Mead algorithm: F=(f cal -f exp ) 2

[0085] Among them, f cal is the calculation result, w moi is the water content of the sample, Δt is the time step, c A and c E are the correction coefficients of E and lnA, respectively, exp are experimental measured values.

[0086] The data obtained by solving is as follows Figure 3 As shown;

[0087] (4) Perform secondary correction to improve calculation accuracy.

[0088] according to Figure 3 According to the data rules in , the mathematical function relationship between the correction coefficient and the heating rate is established:

[0089] Substitute the above formula into the following formula: F=∑(f cal,i -f exp,i ) 2

[0090] Among them, f cal,i and f exp,i are the calculated and experimental results at different heating rates, w moi,i The water content of the sample at different heating rates Quantity, Δt i is the time step at different heating rates, T i is the temperature data under different heating rates;

[0091] Use the Nelder-Mead algorithm again to solve the coefficients in the functional relationship and get: a=0.03557, b=0.00388, c=0.001512, d=0.5843

[0092] Through secondary correction, the accuracy of water evaporation rate calculation is further improved, and finally the high-precision calculation of water evaporation rate of wood biomass is achieved. Figure 4 shown.

[0093] In summary, this embodiment provides a method for calculating and improving the water evaporation rate of wood biomass based on thermogravimetric experiments. Through multiple thermogravimetric experiments and mathematical modeling, high-precision calculation of the water evaporation rate of wood biomass is achieved. The present invention can provide a method reference for calculating the water evaporation rate during the heating and combustion of wood biomass.

[0094] 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 improving the evaporation rate of wood biomass water based on thermogravimetric experiments, characterized in that: The method comprises: Multiple thermogravimetric experiments on woody biomass were conducted in the water evaporation temperature range at different heating rates; The water evaporation process is regarded as a chemical reaction process, and the average apparent activation energy E and the ln value of the prefactor A at different heating rates are solved based on the thermogravimetric curve. The Arrhenius formula was used to preliminarily calculate the water evaporation rate at different heating rates; Correction coefficients were introduced into E and lnA in the preliminary calculation formula of water evaporation rate at each heating rate, and the correction coefficients were solved using the Nelder-Mead algorithm to establish the functional relationship between the correction coefficients and the heating rate. The coefficients in the functional relationship are solved again using the Nelder-Mead algorithm, and a secondary correction is performed to improve the calculation accuracy of the water evaporation rate, thereby achieving the calculation and accuracy improvement of the water evaporation rate of wood biomass.

2. The method for calculating and improving the evaporation rate of woody biomass water based on thermogravimetric experiments according to claim 1, characterized in that: The thermogravimetric experiment is carried out at different heating rates, including: Select representative woody biomass samples to ensure that their physical properties such as type, moisture content, density, etc. meet the research requirements; A high-precision thermogravimetric analyzer was used to perform a programmed temperature experiment on wood biomass samples, and the mass change data of the samples at different heating rates were recorded; Determine the water evaporation temperature range and ensure that the experiment covers the key temperature points within this range.

3. The method for calculating and improving the evaporation rate of wood biomass water based on thermogravimetric experiment according to claim 1, characterized in that: The method of solving the ln value of the average apparent activation energy E and the pre-factor A based on the thermogravimetric curve includes: Analyze the thermogravimetric curves at different heating rates to extract key parameters in the water evaporation process, such as the starting evaporation temperature, the temperature of the maximum weight loss rate, etc. The KAS method is used to solve the ln value of the average apparent activation energy E and the prefactor A.

4. The method for calculating and improving the evaporation rate of wood biomass water based on thermogravimetric experiment according to claim 1, characterized in that: The preliminary calculation is performed using the Arrhenius formula, including: Substitute the obtained average apparent activation energy E and the ln value of the prefactor A into the Arrhenius formula; Calculate preliminary values ​​of water evaporation rate of woody biomass at different heating rates.

5. The method for calculating and improving the evaporation rate of water from woody biomass based on thermogravimetric experiments according to claim 1, characterized in that: The introducing and solving of the correction coefficient comprises: Introduce correction coefficients c into E and lnA in the preliminary calculation formula of water evaporation rate at each heating rate E and c A ; The formula is as follows: F=(f cal -f exp ) 2 Among them, f cal is the calculation result, w moi is the water content of the sample, Δt is the time step, c A and c E are the correction coefficients of E and lnA, respectively, exp are experimental measured values.

6. The method for calculating and improving the evaporation rate of wood biomass water based on thermogravimetric experiment according to claim 1, characterized in that: The step of establishing a functional relationship between the correction coefficient and the heating rate comprises: Analyze the variation of correction coefficient under different heating rates; Establish the mathematical function relationship between the correction factor and the heating rate:

7. The method for calculating and improving the evaporation rate of wood biomass water based on thermogravimetric experiment according to claim 1, characterized in that: The secondary correction comprises: Substitute the mathematical function relationship between the above correction factor and the heating rate into the following calculation formula: F=∑(f cal,i -f exp,i ) 2 Among them, f cal,i and f exp,i are the calculated and experimental results at different heating rates, w moi,i is the water content of the sample at different heating rates, Δt i is the time step at different heating rates, T i is the temperature data under different heating rates; The Nelder-Mead algorithm is used again to calculate the minimum value of the above formula to solve the coefficients in the functional relationship. The Nelder-Mead algorithm is used again to solve the coefficients in the functional relationship; Through secondary correction, the accuracy of water evaporation rate calculation is further improved.

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