Method for constructing a simplified model of combustion reaction of high-volatile organic dust and system thereof

Abstract

The present application relates to the field of organic dust, in particular to a kind of high volatile organic dust multi-step combustion reaction skeleton construction method and system thereof.The construction method of the simplified model includes the following steps: industrial analysis and element analysis are carried out on organic dust;Organic dust is continuously heated, and the mass, mass loss rate and heat release rate of organic dust are collected;According to the inflection point of mass loss rate curve, the pyrolysis process is divided into slow pyrolysis stage and rapid pyrolysis stage;The volume ratio of different molecular weight gas is calculated;The type and mass percentage of gas are determined according to element analysis and volume ratio;The rate constant k of slow pyrolysis stage and rapid pyrolysis stage is fitted in sections, and the combustion reaction of organic dust gas phase volatile matter is simplified using Chemkin-Pro software.The present application is helpful to construct the simplified model of multi-step combustion reaction of various high volatile organic dust and realize the output of results, and provides a new direction for the study of high volatile organic dust combustion reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic dust, in particular to a method for constructing a multi-step combustion reaction skeleton of high-volatility organic dust and a system thereof. BACKGROUND

[0002] Organic dust is a renewable biomass fuel with wide application prospects. Studying the pyrolysis parameters and combustion reactions of gas-phase volatile components of organic dust is of great significance to efficient energy utilization, low-pollution emission, and chemical process design. At present, research on dust combustion is mostly from the macroscopic perspective to analyze the apparent combustion characteristics of dust particles. There are still many deficiencies and difficulties in the study of dust combustion reactions and kinetic parameters at the microscopic level.

[0003] At present, there are many detailed chemical reaction steps for gas combustion, which have been supplemented and improved based on a large amount of experimental data. In particular, the chemical reactions of hydrocarbon gases have been accurately detailed. Unlike gas combustion, the volatile components produced by organic dust pyrolysis are composed of multiple gases, and the pyrolysis products contain a certain proportion of fixed carbon components. Therefore, the combustion process of organic dust is a multiphase combustion system with coexistence of solid particles, gas-phase volatile components, and oxidants, which is a complex system involving momentum, energy, and mass coupling transmission in a multiphase system. At present, there is no effective modeling method for the kinetic model of the organic dust pyrolysis process.

[0004] Therefore, it is necessary to construct a multi-step combustion reaction skeleton suitable for organic dust and to effectively verify its accuracy and effectiveness. SUMMARY

[0005] One of the purposes of the present application is to provide a method for constructing a simplified model of high-volatility organic dust combustion reaction, which is accurate and practical, and provides a new direction for the study of organic dust combustion reaction.

[0006] The technical scheme of the method for constructing a simplified model of high-volatility organic dust combustion reaction of the present application is as follows:

[0007] The method for constructing a simplified model of high-volatility organic dust combustion reaction comprises the following steps:

[0008] S1, performing industrial analysis and elemental analysis on the organic dust;

[0009] S2, continuously heating the organic dust in an inert gas atmosphere, and collecting the mass, mass loss rate, and heat release rate of the organic dust, and dividing the organic dust pyrolysis process into a slow pyrolysis stage and a rapid pyrolysis stage according to the inflection point of the mass loss rate curve;

[0010] S3, detecting average ion current intensity of different molecular weight gases in the continuous temperature rising process and obtaining the curve of the average ion current intensity changing with temperature, then integrating the average ion current intensity to obtain the relative content of different molecular weight gases, and further obtaining the volume ratio of different molecular weight gases;

[0011] S4, determining the types and mass percentages of different molecular weight gases according to the elemental analysis in S1 and the volume ratio of different molecular weight gases in S3;

[0012] S5, segment fitting the rate constant k of the slow pyrolysis stage and the fast pyrolysis stage based on the mass loss rate curve in S2, and obtaining the E and A values of the slow pyrolysis stage and the fast pyrolysis stage respectively;

[0013] S6, using the zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure combustor model of the Chemkin-Pro software to simplify the combustion reaction of the gas-phase volatile components of the organic dust;

[0014] S7, comparing the prediction effects of the simplified combustion reaction obtained in S6 and the detailed reaction laminar flame speed and adiabatic flame temperature, when the relative error of the two is <10%, the simplified model is reasonable, otherwise it needs to return to S5 for further optimization of the simplified reaction.

[0015] Preferably, in S5, the rate constant k is segment fitted based on the mass loss rate curve in S2, and the relationship between the rate constant k and the temperature T is shown in formula (1),

[0016]

[0017] In formula (1), A is the pre-exponential factor; E is the pyrolysis reaction activation energy, J·mol -1 ; R is the universal gas constant, 8.314 J·mol -1 ·K -1 ;

[0018] The relationship between the continuous temperature rising rate β and the instantaneous pyrolysis volatilization rate α in S2 is shown in formula (2),

[0019]

[0020] In formula (2), the instantaneous pyrolysis volatilization rate α=(M0-M) / (M0-M ∞ )×100%, wherein M0, M and M ∞ are the initial mass of the organic dust, the instantaneous remaining mass and the remaining mass after the pyrolysis is completed, respectively, and the unit is g; g(α)=-ln(1-α) in the slow pyrolysis stage, and g(α)=(1-α) -1 -1 in the fast pyrolysis stage;

[0021] Taking logarithm on both ends of formula (2), formula (3) can be obtained,

[0022]

[0023] In formula (3), assuming E / RT>>1, (1-2RT / E)≈1, ln(AR / βE) is a constant value, therefore, ln[g(α) / T 2 ] and 1 / T approximately satisfy a linear function shown in formula (4), linear fitting can obtain the optimal solution of the slope-E / R and the intercept ln(AR / βE) of the linear function, and then obtain the E and A values of the slow pyrolysis stage and the fast pyrolysis stage respectively;

[0024]

[0025] Further preferably, in S6, the combustion reaction of the gas-phase volatile component of the organic dust is simplified by using a zero-dimensional constant-volume explosion model and a one-dimensional constant-pressure combustor model of Chemkin-Pro software, wherein the reaction rate constant k g As shown in formula (5),

[0026]

[0027] In formula (5), k0 and k ∞ are the reaction rate constants under low pressure and high pressure conditions respectively, E0 and E ∞ are the activation energies under low pressure and high pressure conditions respectively, [M] is the molar concentration of the gas, n0 and n ∞ are the temperature exponents under low pressure and high pressure conditions respectively, A0 and A ∞ are the pre-exponential factors under low pressure and high pressure conditions respectively.

[0028] Preferably, in S1, the organic dust is one or more of coal powder, cotton powder, hemp powder, grain powder, flax powder, sugarcane powder, wood powder, tea powder, resin powder, organic dye powder, synthetic fiber powder, and synthetic rubber powder.

[0029] Preferably, in S1, the proximate analysis includes measuring the mass fractions of volatile matter, fixed carbon, moisture, and ash of the organic dust, and the elemental analysis includes measuring the mass fractions of C, H, S, N, and O elements of the organic dust.

[0030] Preferably, in S2, the organic dust is continuously heated to 1800K-2000K in an inert gas atmosphere, and a TG-DSC thermal analyzer is used to collect the mass, mass loss rate, and heat release rate of the organic dust in real time during the continuous heating process.

[0031] Further preferably, in S6, the combustion reaction simplification is based on the entire reaction, and a generation rate analysis and a sensitivity analysis are performed on main groups and reaction steps to obtain groups with obvious changes in concentration and main reaction steps affecting the changes.

[0032] Still further preferably, the zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure combustor model use finite difference method to perform time and space discretization on the control equations, and use high-order QUCK format to discretize the convection term and use second-order upwind format to discretize the heat conduction term; groups with obvious changes in component concentration in the chemical reaction and main reactions affecting the changes are obtained to determine the simplified model of the high-volatility organic dust combustion reaction.

[0033] The second object of the present application is to provide a high-volatility organic dust combustion reaction simplification model system, which is helpful to construct a simplified model of multi-step combustion reaction of various organic dusts and realize result output.

[0034] The technical scheme of the high-volatility organic dust combustion reaction simplification model system of the present application is as follows:

[0035] The high-volatility organic dust combustion reaction simplification model system comprises:

[0036] The pyrolysis kinetics model construction module (1) obtains industrial analysis and element analysis data of the organic dust; (2) real-time collects mass, mass loss rate, and heat release rate data of the organic dust in the continuous temperature rising process, and automatically divides the pyrolysis process of the organic dust into a slow pyrolysis stage and a rapid pyrolysis stage at the inflection point of the mass loss rate curve; (3) real-time collects average ion current intensity of different molecular weight gases in the continuous temperature rising process and obtains a curve of the average ion current intensity varying with temperature, and integrates the average ion current intensity in the entire test temperature range to obtain relative contents of the different molecular weight gases; (4) establishes and solves a multivariate linear equation set to determine the types and mass percentages of the different molecular weight gases; and (5) performs segmented fitting on the rate constant k of the slow pyrolysis stage and the rapid pyrolysis stage of the organic dust.

[0037] The gas phase volatile component reaction kinetics model simplification module uses the zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure combustor model of the Chemkin-Pro software to simplify the detailed gas phase combustion reaction mechanism Mech-3.0 of the gas phase volatile component of the organic dust.

[0038] The model precision judgment and correction module compares the prediction effects of the obtained simplified combustion reaction of the gas phase volatile component and the original detailed chemical reaction mechanism Mech-3.0 on the laminar flame speed and the adiabatic flame temperature, and when the relative error of the two is less than 10%, the simplified combustion reaction of the gas phase volatile component of the organic dust is reasonable, otherwise the M2 needs to be returned for further optimization.

[0039] The output display module displays and outputs (1) the organic dust pyrolysis process curve, the slow pyrolysis stage and the fast pyrolysis stage pyrolysis kinetics parameters; (2) the proportion of different molecular weight gases in unit mass of organic dust; (3) the simplified model of multi-step combustion reaction of high-volatility organic dust; (4) the relative error of the prediction results of the laminar flame speed and the adiabatic flame temperature of the simplified reaction model and the original detailed chemical reaction mechanism Mech-3.0.

[0040] Beneficial effects:

[0041] The application provides a construction method and system of a high-volatility organic dust combustion reaction simplified model, which is accurate and practical, and provides a new direction for the research on high-volatility organic dust combustion reaction; the system is helpful for constructing a simplified model of multi-step combustion reaction of various high-volatility organic dusts and realizing result output. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The construction flowchart of the high-volatility organic dust combustion reaction simplified model of the application;

[0043] Figure 2 The TG-DSC curve of corn starch in Example 2 of the application;

[0044] Figure 3 The TG curve and gas relative concentration change graph of corn starch in Example 2 of the application;

[0045] Figure 4 In the figure, a is the Coats-Redfern integral method pyrolysis reaction fitting curve graph of the first stage of corn starch pyrolysis in Example 2 of the application; b is the Coats-Redfern integral method pyrolysis reaction fitting curve graph of the second stage of corn starch pyrolysis in Example 2 of the application;

[0046] Figure 5 In the figure, a is the CH4 generation rate analysis graph in the constant-volume explosion process of the volatile matter of corn starch in Example 2 of the application; b is the CO generation rate analysis graph in the constant-volume explosion process of the volatile matter of corn starch in Example 2 of the application; c is the H2 generation rate analysis graph in the constant-volume explosion process of the volatile matter of corn starch in Example 2 of the application; d is the O2 generation rate analysis graph in the constant-volume explosion process of the volatile matter of corn starch in Example 2 of the application;

[0047] Figure 6In the figure, a is the sensitivity analysis diagram of CH4 at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; b is the sensitivity analysis diagram of H2 at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; c is the sensitivity analysis diagram of CO at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; d is the sensitivity analysis diagram of OH at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application;

[0048] Figure 7 In the figure, a is the sensitivity analysis diagram of CH4 at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; b is the sensitivity analysis diagram of H2 at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; c is the sensitivity analysis diagram of CO at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; d is the sensitivity analysis diagram of OH at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application;

[0049] Figure 8 In the figure, a is the sensitivity analysis diagram of CH4 at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; b is the sensitivity analysis diagram of H2 at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; c is the sensitivity analysis diagram of CO at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; d is the sensitivity analysis diagram of OH at different initial temperatures of the volatile matter of corn starch in Example 2 of the present application; DETAILED DESCRIPTION

[0050] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0051] Example 1

[0052] A method for constructing a simplified model of combustion reaction of high-volatility organic dust, comprising the following steps:

[0053] S1, select an organic dust and test the physical parameters, perform industrial analysis (including volatile matter, fixed carbon, moisture and ash) and elemental analysis (including C, H, S, N and O elements) to prepare the composition and percentage of the gas phase volatile matter of the organic dust. The organic dust includes animal dust such as hair, plant dust such as cotton and hemp, and organic dust such as organic dyes. In order to eliminate the influence of moisture on the test results as much as possible, the organic dust is dried in a 50℃ vacuum drying oven for 4h before the experiment.

[0054] S2, using a simultaneous thermal analyzer TG-DSC to continuously heat the organic dust to 1800K-2000K and collect the mass, mass loss rate, heat release rate in real time to obtain the combustion characteristic parameter information and corresponding reaction kinetic parameters of the organic dust decomposition process. The information of the organic dust decomposition process is divided into three stages, the first stage, the water in the organic dust is evaporated by heating, resulting in a decrease in the mass of the solid, so that a weight loss peak appears on the DTG curve of the thermal analyzer, and the TG curve also decreases; the second stage, the mass of the solid decreases by more than 70wt%, and the DTG curve appears a "concave" weight loss peak greater than the first stage; the third stage, the coke produced by the pyrolysis of the organic dust decomposes.

[0055] According to the inflection point of the mass loss rate curve, the second stage is divided into a slow pyrolysis stage and a fast pyrolysis stage; the average reaction rate (dm / dt) mean and the combustibility index S of the organic dust are represented by equations (6) and (7) respectively, and a larger combustibility index indicates that the organic dust has stronger reaction activity,

[0056]

[0057] S=(dm / dt) max ·(dm / dt) mean / (T i 2 ·T max ) (7)

[0058] Wherein, m is the mass of the organic dust, m0 is the initial mass of the sample organic dust, α is the conversion rate, T max is the peak temperature, T i is the ignition temperature, and β is the heating rate.

[0059] S3, detecting the real-time release of gas phase volatile matter in the combustion process of the organic dust by a TG-MS simultaneous thermal analyzer to obtain the curve of gas content changing with temperature. The average ion current intensity of different molecular weight gases is tested to obtain the curve of the average ion current intensity changing with temperature, and the relative content of different molecular weight gases is obtained by integrating in the entire test temperature range, and then the proportion of different molecular weight gases is obtained. Since the molecular weights of some gases are the same, all the gases cannot be completely distinguished at this time.

[0060] S4, combining the elemental analysis results in S1 and the TG-MS experimental results in step S3 to obtain the types and percentages of different molecular weight gases of the organic dust. The TG-MS method provides a relatively reliable test method for obtaining the composition of gas phase volatile matter. According to the conservation of elements, the accuracy of the composition and percentage of the gas phase volatile matter of the organic dust is further verified by a theoretical calculation method.

[0061] S5, the rate constant k of the organic dust slow pyrolysis stage and fast pyrolysis stage is segmented fitted using the CR integral method, and the organic dust pyrolysis reaction function and segmented pyrolysis reaction kinetic parameters are obtained. The thermal gravimetric curve obtained by only one heating rate can obtain the two-stage pyrolysis kinetic parameters.

[0062] The relationship between the rate constant k and the temperature T is shown in formula (8),

[0063]

[0064] In formula (1), A is a pre-exponential factor; E is a pyrolysis reaction activation energy, J·mol -1 ·K -1 ·K -1 ;

[0065] The relationship between the continuous heating rate β and the instantaneous pyrolysis volatile rate α (the pyrolysis volatile rate is essentially the mass loss rate) in S2 is shown in formula (9),

[0066]

[0067] In formula (9), the instantaneous pyrolysis volatile rate α = (M0-M) / (M0-M ∞ )×100%, wherein M0, M and M ∞ are the initial mass of the organic dust, the instantaneous remaining mass of the organic dust and the remaining mass of the organic dust after the pyrolysis is completed, respectively, in g; g(α) is a function determined by the decomposition reaction mechanism of the substance, g(α) = -ln(1-α) in the slow pyrolysis stage and g(α) = (1-α) -1 -1 in the fast pyrolysis stage;

[0068] Taking the logarithm of both ends of formula (9), formula (10) is obtained,

[0069]

[0070] In formula (10), for a general reaction temperature range and the pyrolysis activation energy of most organic dust, E / RT>>1, so (1-2RT / E)≈1, and ln(AR / βE) is a constant value, so ln[g(α) / T 2 ] and 1 / T approximately satisfy a linear function shown in formula (11),

[0071]

[0072] The discrete data points of the pyrolysis volatile rate α changing with the heating temperature T obtained in S2 can be converted into ln[g(α) / T 2The discrete data points corresponding to 1 / T are linearly fitted by using the least square method to obtain the optimal solution of the slope of the first order function E / R and the intercept ln(AR / βE), and then the values of E and A in the slow pyrolysis stage and the fast pyrolysis stage can be obtained respectively;

[0073] The change relationship of the pyrolysis rate constant with temperature is as follows:

[0074]

[0075] S6, the detailed gas phase combustion reaction mechanism Mech-3.0 of the gas phase volatile matter of the organic dust is simplified by using the zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure combustor model in the Chemkin-Pro software, and the simplification method is the direct relationship diagram method (DRGEP) based on error propagation, wherein the reaction rate constant k of the gas phase single molecule / complex decay reaction g As shown in formula (13),

[0076]

[0077] In formula (13), k0 and k ∞ are the reaction rate constants under low pressure and high pressure conditions respectively, E0 and E ∞ are the activation energies under low pressure and high pressure conditions respectively, [M] is the molar concentration of the gas, n0 and n ∞ are the temperature exponents under low pressure and high pressure conditions respectively, A0 and A ∞ are the pre-exponential factors under low pressure and high pressure conditions respectively.

[0078] On the basis of the full reaction, the formation rate analysis and the sensitivity analysis are performed on the main groups and the reaction steps according to the composition of the gas phase volatile matter of the organic dust obtained in the above steps, the groups with obvious changes in concentration and the main reaction steps affecting the changes are obtained, and the simplified model of the combustion reaction of the high-volatility organic dust is determined. The zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure combustor model use the finite difference method to discretize the control equations in time and space, and the convection term is discretized by using the high-order QUCK format, and the heat conduction term is discretized by using the second-order upwind format.

[0079] S7, the prediction effects of the volatile matter simplified combustion reaction mechanism obtained in S6 and the original detailed chemical reaction mechanism Mech-3.0 on the laminar flame speed and the adiabatic flame temperature are compared to verify the accuracy of the simplified reaction in S6. When the relative errors of the two are both less than 10%, it is considered that the simplified combustion reaction mechanism of the organic dust volatile matter determined in S6 is reasonable and reliable, otherwise it is necessary to return to S6 to further optimize the simplified result.

[0080] The flow of the construction method is shown in Figure 1 .

[0081] Example 2

[0082] A method for constructing a high volatile organic dust combustion reaction simplified model, comprising the following steps:

[0083] S1, corn starch is selected as the research object, and industrial analysis and element analysis are performed on the corn starch. The element analysis results are that C element accounts for 40.80%, H element accounts for 6.56%, S element accounts for 1.35%, and O element accounts for 48.55%. The industrial analysis results are that volatile matter accounts for 87.69%, fixed carbon accounts for 4.25%, moisture accounts for 7.94%, and ash accounts for 0.12%.

[0084] S2, a TG-DSC synchronous thermal analyzer is used to collect and obtain information of a corn starch decomposition process and corresponding combustion characteristic parameters in a continuous heating process of the corn starch in real time, and a TG-DSC test result is as shown in Figure 2 . The pyrolysis process of the corn starch in nitrogen mainly consists of three stages. In the first stage, a smaller weight loss peak appears on a DTG curve of the corn starch, and a TG curve also appears to decrease. The reason for weight loss in this stage is mainly that water is evaporated by heating. Stages II and III are two stages with relatively fast pyrolysis speed. Almost 76% of weight loss of the corn starch occurs in stage II, and a significant “concave” weight loss peak appears on the DTG curve. In the third stage, coke produced by pyrolysis is decomposed in this stage. The average reaction rate (dm / dt) mean and the combustibility index S are represented by the following formula:

[0085]

[0086] S=(dm / dt) max ·(dm / dt) mean / (T i 2 ·T max ) (15)

[0087] Wherein, m is the mass of the organic dust (corn starch in this embodiment), m0 is the initial mass of the sample, α is the conversion rate, T max is the peak temperature, T i is the ignition temperature, and β is the heating rate.

[0088] S3, a TG-MS synchronous thermal analyzer is used to detect real-time release of different molecular weight gases in a corn starch combustion test, and a curve of gas content changing with temperature is obtained. As can be known from Figure 3 , CH4 is the first combustible gas to be precipitated, followed by CO and H2, accompanied by a small amount of SO2 and CO2.

[0089] The average ion current intensity versus temperature curve was obtained for each gas, and the total amount of volatile matter per unit mass of corn starch was obtained by integrating the curve over the entire test temperature range. According to the obtained peak area ratio of the gases, the gas components in the volatile matter of corn starch were as follows: the volume ratio of CH4, H2 and CO was 9.4%, 34.4% and 55.1% respectively, and the remaining gas components accounted for only 1.1%.

[0090] S4, the composition and percentage of the volatile matter of corn starch were determined according to the elemental analysis results in S1 and the TG-MS experimental results in S3. According to the elemental composition of the volatile matter (40.80% of C element, 6.56% of H element and 48.55% of O element) in step S1, the composition of the volatile matter was mainly considered to be CO, H2 and CH4, and the amounts of CO, H2 and CH4 could be calculated according to the element conservation. Therefore, the theoretically calculated composition of the volatile matter was CH4-9.5%, H2-34.7% and CO-55.8%. The maximum error between the theoretically calculated composition of the volatile matter and the experimental results was 3.7%, and therefore the TG-MS method in step S3 provided a relatively reliable experimental method for obtaining the composition of the volatile matter.

[0091] S5, the pyrolysis rate constants of the slow pyrolysis stage and the fast pyrolysis stage of corn starch were fitted by using the CR integral method as shown below to obtain the first-order approximate Coats-Redfern integral equation of corn starch. Figure 4 The Coats-Redfern integral method pyrolysis reaction fitting curve of corn starch;

[0092]

[0093]

[0094] The arrangement is as follows:

[0095]

[0096] Taking the logarithm of both ends, we have

[0097]

[0098] For a general reaction temperature range and most of the reaction activation energy, E / RT>>1, then (1-2RT / E)≈1, ln[AR / βE] is a constant value, that is, 1 / T and ln[g(α) / T 2 ] are linearly related. The activation energy E is converted from the slope of the fitting relationship, and the pre-exponential factor A can be obtained according to the intercept.

[0099] The temperature range, reaction rate function, activation energy and pre-exponential factor of the slow pyrolysis stage and the fast pyrolysis stage of corn starch are shown in Table 1.

[0100] Table 1 Coats-Redfern integral form kinetic reaction fitting results of corn starch

[0101]

[0102]

[0103] S6, the zero-dimensional constant volume explosion model and one-dimensional constant pressure combustor model in Chemkin-Pro were selected to simplify the multi-step combustion reaction of corn starch volatiles. Based on the full reaction, the formation rate analysis and sensitivity analysis were performed on the main groups and reaction steps according to the composition of the corn starch volatiles obtained in the previous steps. Figure 5 is the formation rate analysis diagram of the main components in the constant volume explosion process of corn starch volatiles.

[0104] The one-dimensional constant pressure combustor model was used to simulate the laminar combustion process, and the components with obvious changes in concentration in the flame surface included H2, CO, CH4, OH, H, CO2, H2O, etc. Figure 6 is the component sensitivity analysis diagram of corn starch volatiles at different initial temperatures. Taking the analysis of combustible gas reactants CO, H2 and their products H2O, CO2 as an example: the elementary reactions R99 (OH+CO→H+CO2) and R84 (OH+H2→H+H2O) are the most important elementary reaction steps. For CO, as the initial temperature increases, the sensitivity coefficients of R99 (OH+CO→H+CO2), R84 (OH+H2→H+H2O), R98 (OH+CH4→CH3+H2O) and R11 (O+CH4→OH+CH3) gradually decrease; the sensitivity coefficients of R36 (H+O2+N2→HO2+H2O), R38 (H+O2→O+OH), R43 (H+OH+M→H2O+M) and R284 (O+CH3→H+H2+CO) increase, which indicates that as the temperature increases, the above-mentioned elementary reactions play a more significant role in the change of CO concentration. In addition, R46 (H+HO2→2OH) changes from increasing CO concentration to decreasing CO concentration, and R13 (O+HCO→OH+CO) changes from decreasing CO concentration to increasing CO concentration. For each key component, the main reactions of corn starch gas phase volatiles include CO, H2, CH4, H2O, CO2, H, CH3 and CHO, a total of 8 components. Figure 7 is the simplified reaction skeleton diagram of corn starch gas phase volatiles explosion. The simplified explosion reaction of corn starch gas phase volatiles includes a total of 22 steps of elementary reactions, and the simplified reaction of corn starch gas phase volatiles explosion is shown in Table 2.

[0105] Table 2 Simplified reaction of corn starch gas phase volatiles explosion

[0106]

[0107] S7, based on the simplified combustion reaction of corn starch obtained in S6, the prediction effect of the simplified reaction and the detailed reaction of volatile matter on the laminar flame speed and adiabatic flame temperature is obtained, and the accuracy of the simplified reaction in S6 is verified. From Figure 8 It can be seen that the calculation results of the simplified reaction and the detailed reaction on the laminar flame speed and adiabatic flame temperature are not much different, and the error of the parameters is within 7%. Therefore, the simplified reaction obtained can accurately reflect the combustion details of the gas phase volatile matter of corn starch.

[0108] Example 3

[0109] A high-volatile organic dust combustion reaction simplified model system, the system comprising:

[0110] A pyrolysis kinetics model construction module, (1) obtaining the proximate analysis and elemental analysis data of the organic dust; (2) real-time acquisition of the mass, mass loss rate, and heat release rate data of the organic dust during the continuous temperature rising process, and automatically splitting the pyrolysis process of the organic dust into a slow pyrolysis stage and a fast pyrolysis stage at the inflection point of the mass loss rate curve; (3) real-time acquisition of the average ion current intensity of different molecular weight gases during the continuous temperature rising process and obtaining the curve of the average ion current intensity varying with temperature, and integrating the average ion current intensity in the entire test temperature range to obtain the relative content of different molecular weight gas components; (4) establishing and solving a multivariate linear equation system to determine the types and mass percentages of different molecular weight gases; (5) segment fitting the rate constant k of the slow pyrolysis stage and the fast pyrolysis stage of the organic dust;

[0111] A gas phase volatile matter reaction kinetics model simplification module, using the zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure burner model of Chemkin-Pro software to simplify the detailed gas phase combustion reaction mechanism Mech-3.0 of the gas phase volatile matter of the organic dust;

[0112] A model precision judgment and correction module, comparing the prediction effect of the simplified combustion reaction mechanism of the volatile matter and the original detailed chemical reaction mechanism Mech-3.0 on the laminar flame speed and adiabatic flame temperature, when the relative error of the two is <10%, the simplified combustion reaction of the gas phase volatile matter of the organic dust is reasonable, otherwise it needs to return to M2 for further optimization;

[0113] The output display module displays and outputs (1) the organic dust pyrolysis process curve, the slow pyrolysis stage and the fast pyrolysis stage pyrolysis kinetics parameters; (2) the proportion of different molecular weight gas components in unit mass of organic dust; (3) the simplified model of multi-step combustion of high-volatility organic dust; (4) the relative error of the prediction results of the laminar flame speed and the adiabatic flame temperature of the simplified reaction model and the original detailed chemical reaction mechanism Mech-3.0.

[0114] Although the embodiments of the present application have been shown and described above, it should be understood by those skilled in the art that the above embodiments are exemplary and cannot be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for constructing a simplified model of combustion reaction of high volatile organic dust, characterized in that, The method comprises the following steps: S1, performing industrial analysis and element analysis on the organic dust; S2, continuously heating the organic dust in an inert gas atmosphere, collecting the mass, mass loss rate and heat release rate of the organic dust, and dividing the pyrolysis process of the organic dust into a slow pyrolysis stage and a rapid pyrolysis stage according to the inflection point of the mass loss rate curve; S3, detecting the average ion current intensity of different molecular weight gases in the continuous heating process and obtaining the curve of the average ion current intensity changing with temperature, then integrating the average ion current intensity to obtain the relative content of different molecular weight gases, and further obtaining the volume ratio of different molecular weight gases; S4, determining the types and mass percentages of different molecular weight gases according to the element analysis in S1 and the volume ratio of different molecular weight gases in S3; S5, based on the mass loss rate curve in S2, the rate constant k of the slow pyrolysis stage and the rapid pyrolysis stage is fitted in sections to obtain the E and A values of the slow pyrolysis stage and the rapid pyrolysis stage, respectively; S6, using the zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure combustor model of Chemkin-Pro software to simplify the combustion reaction of the gas-phase volatile components of the organic dust; S7, comparing the prediction effect of the simplified combustion reaction obtained in S6 with the detailed reaction laminar flame speed and adiabatic flame temperature, when the relative error of the two is less than 10%, the simplified model is reasonable, otherwise it needs to return to S5 for further optimization of the simplified reaction; In S5, based on the mass loss rate curve in S2, the rate constant k of the slow pyrolysis stage and the rapid pyrolysis stage is fitted in sections, and the relationship between the rate constant k and the temperature T is shown in formula (1), In formula (1), A is a pre-factor; E is a pyrolysis reaction activation energy, J-mol -1 ; R is a universal gas constant, 8.314 J-mol -1 ·K -1 ; The relationship between the continuous heating rate β and the instantaneous pyrolysis volatile rate α in S2 is shown in formula (2), In formula (2), the instantaneous pyrolysis volatilization rate a = (M0 - M) / (M0 - M ∞ ) x 100%, wherein M0, M and M ∞ are the initial mass, the instantaneous remaining mass and the remaining mass after pyrolysis is completed of the organic dust, respectively, in g; g(a) = -ln(l-a) in the slow pyrolysis stage and g(a) = (1-a) in the fast pyrolysis stage -1 -1; Taking the logarithm of both ends of formula (2), formula (3) is obtained, In formula (3), assuming E / RT » 1, (1-2RT / E)≈1, ln(AR / βE) is a constant value, therefore ln[g(α) / T] and 1 / T approximately satisfy a linear function shown in formula (4), and linear fitting can obtain the optimal solution of the slope -E / R and the intercept ln(AR / βE) of the linear function, and further obtain the E and A values of the slow pyrolysis stage and the fast pyrolysis stage respectively. 2 ] and 1 / T approximately satisfy a linear function shown in formula (4), and linear fitting can obtain the optimal solution of the slope -E / R and the intercept ln(AR / βE) of the linear function, and further obtain the E and A values of the slow pyrolysis stage and the fast pyrolysis stage respectively.

2. The method of claim 1, wherein the high volatile organic dust combustion reaction simplified model is constructed by, In S6, the combustion reaction of the gas-phase volatile component of the organic dust is simplified using a zero-dimensional constant-volume explosion model and a one-dimensional constant-pressure combustor model of the Chemkin-Pro software, wherein the reaction rate constant k of the gas-phase monomolecular / complex decay reaction is determined by the Arrhenius equation g As shown in equation (5), In formula (5), k0and k ∞ are reaction rate constants under low pressure and high pressure, respectively, E0and E ∞ are activation energies under low pressure and high pressure, respectively, [M] is the molar concentration of the gas, n0and n ∞ are temperature exponents under low pressure and high pressure, respectively, A0and A ∞ are pre-exponential factors under low pressure and high pressure, respectively.

3. The method of claim 1, wherein the high volatile organic dust combustion reaction simplified model is constructed by, In S1, the organic dust is one or more of coal powder, cotton powder, hemp powder, grain powder, flax powder, sugarcane powder, wood powder, tea powder, resin powder, organic dye powder, synthetic fiber powder and synthetic rubber powder.

4. The method of claim 1, wherein the high volatile organic dust combustion reaction simplified model is constructed by, In S1, the industrial analysis includes measuring the mass fraction of volatile matter, fixed carbon, moisture and ash of the organic dust, and the element analysis includes measuring the mass fraction of C, H, S, N and O elements of the organic dust.

5. The method of claim 1, wherein the high volatile organic dust combustion reaction simplified model is constructed by, In S2, the organic dust is continuously heated to 1800K-2000K in an inert gas atmosphere, and the mass, mass loss rate and heat release rate of the organic dust during the continuous heating process are collected in real time by using a TG-DSC thermal analyzer.

6. The method of constructing a simplified model of the combustion reaction of high volatile organic dust according to any one of claims 1 to 5, characterized in that, In S6, the simplification of the combustion reaction is based on the full reaction, and the formation rate analysis and sensitivity analysis are performed on the main groups and reaction steps to obtain the groups with obvious concentration changes in the reaction and the main reaction steps affecting the changes.

7. The method of claim 6, wherein the high volatile organic dust combustion reaction simplified model is constructed by, The zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure combustor model use finite difference method to discretize the control equations in time and space, and the convection term is discretized by high-order QUCK format, and the heat conduction term is discretized by second-order upwind format; the groups with obvious concentration changes in the chemical reaction and the main reactions affecting the changes are obtained, and the simplified model of the combustion reaction of the high-volatility organic dust is determined.

8. The high volatile organic dust combustion reaction reduced order modeling system of claim 1, wherein, The system comprises: The pyrolysis kinetics model construction module includes the following steps: (1) obtaining the proximate and ultimate analysis data of the organic dust; (2) collecting the mass, mass loss rate and heat release rate data of the organic dust in the continuous heating process in real time, and automatically splitting the pyrolysis process of the organic dust into a slow pyrolysis stage and a rapid pyrolysis stage at the inflection point of the mass loss rate curve; (3) collecting the average ion current intensity of the gas with different molecular weights in the continuous heating process in real time and obtaining the curve of the average ion current intensity varying with temperature, and integrating the average ion current intensity in the whole test temperature range to obtain the relative content of the gas with different molecular weights; (4) establishing and solving a multivariate linear equation set to determine the types and mass percentages of the gas with different molecular weights; and (5) performing segmented fitting on the rate constant k of the slow pyrolysis stage and the rapid pyrolysis stage of the organic dust; The gas phase volatile component reaction kinetics model simplification module simplifies the detailed gas phase combustion reaction mechanism Mech-3.0 of the organic dust gas phase volatile component by using the zero-dimensional constant-volume explosion model and the one-dimensional constant-pressure combustor model of the Chemkin-Pro software; The model precision judgment and correction module compares the prediction effects of the simplified gas phase volatile component combustion reaction and the original detailed chemical reaction mechanism Mech-3.0 on the laminar flame speed and the adiabatic flame temperature, and when the relative error of the two is less than 10%, the simplified gas phase volatile component combustion reaction of the organic dust is reasonable, otherwise the M2 needs to be returned for further optimization; The output display module includes the following steps: (1) displaying and outputting the pyrolysis process curve of the organic dust, the pyrolysis kinetics parameters of the slow pyrolysis stage and the rapid pyrolysis stage; (2) displaying and outputting the proportion of the gas with different molecular weights in the unit mass of the organic dust; (3) displaying and outputting the simplified model of the multi-step combustion reaction of the high-volatility organic dust; and (4) displaying and outputting the relative error of the prediction results of the laminar flame speed and the adiabatic flame temperature of the simplified reaction model and the original detailed chemical reaction mechanism Mech-3.0.

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