A method for calculating the combustion characteristics of the mixed combustion of gasified fine slag and coal with different proportions

Abstract

The present invention belongs to the technical field of coal combustion, and particularly relates to a method for calculating the combustion characteristics of a mixture of gasification fine slag and coal in different proportions. The method of the present invention is proposed based on the basic test data of gasification fine slag and coal. Based on the established basic data model of gasification fine slag and coal, for the new basic data of gasification fine slag and coal, taking the proximate analysis, ultimate analysis, calorific value measured by oxygen bomb calorimeter and their proportions as the original data inputs, a set of targeted calculation models are obtained by fitting using the real combustion data of fuels composed of various proportions of coal and gasification fine slag mixtures. Using this calculation model to predict the ignition temperature, burnout temperature and comprehensive combustion characteristic index of the mixed fuel of the coal to be tested and gasification fine slag, it has the characteristics of being fast, efficient and having a high prediction accuracy. The present invention has high application value in the fields of harmless treatment of gasification fine slag of coal gasification, etc., and has broad development prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal combustion, and particularly relates to a method for calculating the combustion characteristics of a mixture of gasification fine slag and coal in different proportions. Technical Background

[0002] As one of the important means for the current clean and efficient utilization of coal, coal gasification has now become a key focus in the coal chemical industry. However, a large amount of coal gasification fine slag is generated during the coal gasification process, which has a large loss on ignition and a high carbon content. Currently, the most common treatment methods are stacking or landfilling. However, this treatment method not only occupies land resources but also pollutes the soil, surface water, and even groundwater.

[0003] A large number of experiments have shown that co-combusting the gasification fine slag with coal as a fuel in a certain proportion can play a certain synergistic effect. Therefore, co-combusting the gasification fine slag and coal is considered a feasible technical solution for resource utilization. Combustion characteristics have important reference value for characterizing the actual combustion conditions of fuels in boilers and are an important part of fuel combustion theory. The combustion characteristics of mixtures have guiding significance for the application of different mixed raw materials and mixed fuels with different proportions in boilers.

[0004] However, it is unrealistic to repeatedly test the combustion effects of different mixed fuels in industrial boilers. In current research, the combustion effects of the gasification fine slag and coal co-combustion are mainly analyzed by thermogravimetry, which has high requirements for experimental personnel and testing instruments. Moreover, multiple sets of measurements will also require experimental personnel to perform repetitive work, wasting both time and manpower. Therefore, establishing a convenient method for calculating the combustion characteristics of the mixture of gasification fine slag and coal is of great significance for guiding the application of different proportions of gasification fine slag and coal mixed fuels. Summary of the Invention

[0005] The present invention is to solve the problems existing in the prior art and provides a method for quickly calculating the combustion characteristics of a mixture of gasification fine slag and coal in different proportions.

[0006] The present invention adopts the following technical solutions:

[0007] A method for calculating the combustion characteristics of a mixture of gasification fine slag and coal in different proportions, wherein the combustion characteristics include the ignition temperature T, burnout temperature t, and comprehensive combustion characteristic index B, and the method comprises the following steps:

[0008] S1. Taking the moisture content M, volatile matter V, and fixed carbon FC as factors, selecting 10 representative gasification fine slags and 5 coals as experimental samples, respectively conducting proximate analysis, ultimate analysis, calorific value Q, and combustion characteristic tests to obtain different basic data of each gasification fine slag and coal, and establishing a basic database of 10 gasification fine slags and 5 coals;

[0009] S2. For the test sample obtained by mixing unknown types of gasified fine slag and unknown types of coal in different proportions, denote the coal in the test sample as m and the gasified fine slag as n. Obtain various basic data of coal m and gasified fine slag n according to the test method in S1.

[0010] Calculate the sum of the squares of the differences between the basic data of coal m and the corresponding basic data of any kind of coal in the basic database, and select the basic data of the coal in the basic database corresponding to the minimum sum of the calculated squares as the target basic data of coal; Calculate the sum of the squares of the differences between the basic data of gasified fine slag n and the corresponding basic data of any kind of gasified fine slag in the basic database, and select the basic data of the gasified fine slag in the basic database corresponding to the minimum sum of the calculated squares as the target basic data of gasified fine slag; Take the experimental sample providing these two sets of target basic data as the target basic sample, denote the target basic sample corresponding to coal m as sample α, and the target basic sample corresponding to gasified fine slag n as sample β.

[0011] S3. According to the basic data of sample α, calculate the combustion coefficient K of coal m m , K m Specifically, it is the sum of the squares of the differences between each basic data value in sample α and each basic data value of coal m in the test sample multiplied by the corresponding correction coefficient of each basic data; According to the basic data of sample β, calculate the combustion coefficient K of gasified fine slag n n , K n Specifically, it is the sum of the squares of the differences between each basic data value in sample β and each basic data value of gasified fine slag n in the test sample multiplied by the corresponding correction coefficient of each basic data.

[0012] S4. Calculate the combustion characteristics of coal m and gasified fine slag n respectively according to the following formulas. The combustion characteristics include ignition temperature T, burnout temperature t and comprehensive combustion characteristic index B:

[0013] Ignition temperature of coal m In the formula, T α is the ignition temperature of sample α;

[0014] Burnout temperature of coal m In the formula, t α is the burnout temperature of sample α;

[0015] Comprehensive combustion characteristic index of coal m In the formula, B α is the comprehensive combustion characteristic index of sample α;

[0016] Ignition temperature of gasified fine slag n In the formula, T β is the ignition temperature of sample β;

[0017] Burnout temperature of gasification fine slag n In the formula, t β is the burnout temperature of sample β;

[0018] Comprehensive combustion characteristic index of gasification fine slag n In the formula, B β is the comprehensive combustion characteristic index of sample β;

[0019] S5. Suppose the mass fraction of coal m in the sample to be measured is X. Then, for the said sample to be measured:

[0020] Ignition temperature T = 1.22 × T m × X + 1.12 × T n × (1 - X);

[0021] Burnout temperature t = 1.22 × t m × X + t n × (1 - X);

[0022] Combustion characteristic index B = 0.68 × B m × X + 0.9 × B n × (1 - X).

[0023] Preferably, the proximate analysis includes the determination of moisture content M, ash content A, volatile matter V, and fixed carbon FC, and the ultimate analysis includes the determination of carbon element C, hydrogen element H, oxygen element O, nitrogen element N, and sulfur element S.

[0024] Preferably, in the step S3, the correction factors of each index used in the calculation of K m and K n are the same, specifically: the correction factor of moisture content M is 1, the correction factor of ash content A is 1, the correction factor of volatile matter V is 2, the correction factor of fixed carbon FC is 3, the correction factor of carbon element C is 1.5, the correction factor of hydrogen element H is 1.5, the correction factor of oxygen element O is 0.05, the correction factor of nitrogen element N is 0.02, the correction factor of sulfur element S is 0.02, and the correction factor of calorific value Q is 0.17.

[0025] The beneficial effects of the present invention are as follows:

[0026] Based on the basic test data of gasification fine slag and coal, the present invention proposes a set of calculation methods. Based on the established basic data model of gasification fine slag and coal, for the new basic data of gasification fine slag and coal, using the proximate analysis, ultimate analysis, bomb calorific value, and their proportions of the two as the original data input, a set of targeted calculation models are obtained by fitting using the real combustion data of fuels composed of different proportions of various coals and gasification fine slags, and the ignition temperature, burnout temperature, and comprehensive combustion characteristic index of the mixed fuel of the coal to be measured and gasification fine slag are predicted using this calculation model, which has the characteristics of high speed, high efficiency, and high prediction accuracy.

[0027] After experimental verification, the calculation method provided by the present invention calculates the combustion characteristics of the mixture of gasified fine slag and coal with different proportions. Most of the calculation errors are within 5%, and the calculation errors of individual data may exceed 5% but not exceed 10%. This indicates that the calculation method of the present invention is an accurate and efficient calculation method for the combustion characteristics of the mixture of gasified fine slag and coal. The present invention has high application value in the fields of harmless treatment of gasified fine slag and has broad development prospects. Specific Embodiments

[0028] The technical solutions of the present invention will be described in more detail below in conjunction with the embodiments:

[0029] Embodiment 1

[0030] A method for calculating the combustion characteristics of the mixture of gasified fine slag and coal with different proportions, where the combustion characteristics include the ignition temperature T, burnout temperature t, and comprehensive combustion characteristic index B, and the method includes the following steps:

[0031] S1. Taking the moisture content M, volatile matter V, and fixed carbon FC as factors, selecting 10 representative gasified fine slags and 5 coals as experimental samples, respectively conducting proximate analysis, ultimate analysis, calorific value Q, and combustion characteristic tests, obtaining different basic data of each gasified fine slag and coal, and establishing a basic database of 10 gasified fine slags and 5 coals;

[0032] In this embodiment, the selection is based on different gasifiers for producing gasified fine slag and coals with different degrees of coalification. Among them, the gasified fine slags are respectively from Texaco furnace, GSP furnace, Shell furnace, UGI furnace, and Shenhua Ningxia Coal Industry Group furnace. Two samples are taken respectively during the continuous operation of each gasifier as a kind of gasified fine slag, and the second sample is taken 30 days after the first sampling for each gasifier; the coals are anthracite, coking coal, bituminous coal, gas coal, and lignite respectively. The 10 gasified fine slags are numbered C1, C2,..., C 10 , and the 5 coals are numbered G1, G2,..., G5.

[0033] The above proximate analysis includes the determination of moisture content M, ash content A, volatile matter V, and fixed carbon FC, and the ultimate analysis includes the determination of carbon element C, hydrogen element H, oxygen element O, nitrogen element N, and sulfur element S; the proximate analysis is tested according to the GB212 - 91 standard, the ultimate analysis is tested according to the GB / T 476 standard, the calorific value is tested according to the GB213 - 87 standard, and the combustion characteristic test is carried out using a thermogravimetric analyzer.

[0034] S2. For the test sample obtained by mixing unknown types of gasified fine slag and unknown types of coal in different proportions, denote the coal in the test sample as m and the gasified fine slag as n. Obtain various basic data of coal m and gasified fine slag n according to the test method in S1; calculate the sum of squares of the differences between the corresponding basic data of coal m and any kind of coal in the basic database, and select the basic data of the coal in the corresponding basic database with the smallest calculated sum of squares as the target basic data of coal; calculate the sum of squares of the differences between the corresponding basic data of gasified fine slag n and any kind of gasified fine slag in the basic database, and select the basic data of the gasified fine slag in the corresponding basic database with the smallest calculated sum of squares as the target basic data of gasified fine slag; take the experimental sample providing these two sets of target basic data as the target basic sample, denote the target basic sample corresponding to coal m as sample α, and the target basic sample corresponding to gasified fine slag n as sample β.

[0035] The above basic data can be respectively expressed as: the water content M of coal in the test sample m , ash content A m , volatile matter V m , carbon element C m , hydrogen element H m , oxygen element O m , nitrogen element N m , sulfur element S m , calorific value Q m , the water content M of gasified fine slag in the test sample n , ash content A n , volatile matter V n , carbon element C n , hydrogen element H n , oxygen element O n , nitrogen element N n , sulfur element S n , calorific value Q n ;

[0036] Taking the water content M as an example, the corresponding values for gasified fine slag in the basic database are The corresponding values for coal are The representation rules for the remaining data are the same and will not be elaborated.

[0037] Therefore, the process of selecting sample α and sample β in this S2 step can be expressed as follows:

[0038] For gasified fine slag,

[0039]

[0040]

[0041] ……

[0042]

[0043] Take f min = min{f1, d2, d3, …, d 10}, and use the corresponding gasified fine slag sample as the target basic sample, and the corresponding sample is denoted as β;

[0044] For coal,

[0045]

[0046]

[0047] ……

[0048]

[0049] Take f min = min{f1, f2, f3, …, f5}, and use the corresponding coal sample as the target basic sample, and the corresponding sample is denoted as α.

[0050] S3. According to the basic data of sample α and the basic data of coal m in the sample to be tested, calculate the combustion coefficient K m , K m Specifically, it is the sum of the squares of the differences between each basic data value in sample α and each basic data value of coal m in the sample to be tested, multiplied by the correction coefficient corresponding to each basic data; According to the basic data of sample β and the basic data of gasified fine slag n in the sample to be tested, calculate the combustion coefficient K n , K n Specifically, it is the sum of the squares of the differences between each basic data value of sample β and each basic data value of gasified fine slag n in the sample to be tested, multiplied by the correction coefficient corresponding to each basic data;

[0051] In the present invention, the correction coefficients of each basic data used in the calculation of K M and K N are the same. Specifically: the correction coefficient of moisture content M is 1, the correction coefficient of ash content A is 1, the correction coefficient of volatile matter V is 2, the correction coefficient of fixed carbon FC is 3, the correction coefficient of carbon element C is 1.5, the correction coefficient of hydrogen element H is 1.5, the correction coefficient of oxygen element O is 0.05, the correction coefficient of nitrogen element N is 0.02, the correction coefficient of sulfur element S is 0.02, and the correction coefficient of calorific value Q is 0.17.

[0052] The calculation method of the above correction coefficient is as follows: Assign values to each basic data according to the importance of different basic data and confirm the verification range. For the correction coefficients of moisture content M, ash content A, volatile matter V, and fixed carbon FC, they are incrementally valued from 0 to 5 at intervals of 0.1; the correction coefficients of carbon element C and hydrogen element H are incrementally valued from 0 to 2 at intervals of 0.1; oxygen element O, nitrogen element N, sulfur element S, and calorific value Q are incrementally valued from 0 to 1 at intervals of 0.01. In the basic database, any two of the 5 coal samples are subjected to orthogonal tests according to their respective basic data values to obtain a batch of calculated K M data sets, and find the average value of the K M data sets. Finally, select the K M value that is closest to the average value as the final coefficient in the M calculation formula; the coefficients of the gasification fine slag use the coefficients calculated from the coal. Then, the calculation formula of the combustion coefficient K can be expressed as follows:

[0053] K m =(M α -M m ) 2 +2×(V α -V m ) 2 +(A α -A m ) 2 +3×(FC α -FC m ) 2

[0054] +1.5×(C α -C m ) 2 +1.5×(H α -H m ) 2

[0055] +0.05×(O α -O m ) 2 +0.02×(N α -N m ) 2

[0056] +0.02×(S α -S m ) 2 +0.17×(Q α -Q m ) 2

[0057] K n =(M β -Mn ) 2 +2×(V β -V n ) 2 +(A β -A n ) 2 +3×(FC β -FC n ) 2

[0058] +1.5×(C β -C n ) 2 +1.5×(H β -H n ) 2 +0.05×(O β -O n ) 2

[0059] +0.02×(N β -N n ) 2 +0.02×(S β -S n ) 2

[0060] +0.17×(Q β -Q n ) 2

[0061] S4. Calculate the combustion characteristics of coal m and gasification fine slag n respectively according to the following formulas. The combustion characteristics include ignition temperature T, burnout temperature t, and comprehensive combustion characteristic index B:

[0062] Ignition temperature of coal m where T α is the ignition temperature of sample α;

[0063] Burnout temperature of coal m where t α is the burnout temperature of sample α;

[0064] Comprehensive combustion characteristic index of coal m where B α is the comprehensive combustion characteristic index of sample α;

[0065] Ignition temperature of gasification fine slag n where T β is the ignition temperature of sample β;

[0066] Burnout temperature of gasification fine slag n where t β is the burnout temperature of sample β;

[0067] Comprehensive combustion characteristic index of gasified fine slag In the formula, B β is the comprehensive combustion characteristic index of sample β.

[0068] The determination method of the coefficients in the above formula is as follows: The data are respectively assigned values according to linear experience. Among them, the ignition temperature and burnout temperature are incrementally assigned values from 1 to 100 at an interval of 1, and the comprehensive combustion characteristic index is incrementally assigned values from 0 to 200 at an interval of 10. A simulation prediction is carried out between any two coal samples, and the deviations between the predicted values and the actual values are added up. Finally, the values used in the group with the smallest deviation among all simulation predictions are used as the final coefficients. The prediction methods for the coefficients of gasified fine slag are the same.

[0069] S5. Obtain relevant calculation coefficients based on data of a large number of mixed fuels with different proportions. Use 10 gasified fine slag samples and 5 coal samples in the basic database to cross - compose 50 mixed fuel combinations; the mixing ratios are five ratios of 1 / 9, 3 / 7, 5 / 5, 7 / 3, and 9 / 1, totaling 250 mixed fuels. Randomly number the 250 mixed fuels, and randomly select 10 mixed fuels for experimental testing. Calculate the ignition temperature, burnout temperature, and combustion characteristic index, and use them as standard data to calculate the calculation coefficients of the mixed fuels.

[0070] Taking the ignition temperature as an example, in the mixed sample, the coefficient of coal is incrementally assigned values from 0.5 to 1.5 at an interval of 0.02 in sequence, and the coefficient of gasified fine slag is incrementally assigned values from 0.5 to 1.5 at an interval of 0.02 in sequence. A simulation prediction is carried out in sequence in the selected combination, and the error between each predicted value and the experimental calculated value is obtained. Finally, a set of coefficients with the smallest sum of errors is selected as the coefficients of the calculation formula. The same applies to the burnout temperature and the combustion characteristic index.

[0071] After calculation, for the gasified fine slag and coal mixed samples to be tested in S2, assuming the mass fraction of coal m in the mixture of the gasified fine slag to be tested and coal is X, then:

[0072] Ignition temperature T = 1.22×T m ×X + 1.12×T n ×(1 - X);

[0073] Burnout temperature t = 1.22×t m ×X + t n ×(1 - X);

[0074] Combustion characteristic index B = 0.68×B m ×X + 0.9×B n ×(1 - X).

[0075] Example 2

[0076] For a coal gasification fine slag and coal mixed sample to be calculated, the properties of coal m and gasification fine slag n are measured respectively as follows:

[0077]

[0078] Note: The above basis is air-dried basis.

[0079] Referring to the steps in Example 1, f min = 0.25, h min = 0.24, and the properties of the corresponding coal sample α and gasification fine slag sample β are as follows:

[0080]

[0081] Note: The above basis is air-dried basis.

[0082] The ignition temperature T, burnout temperature t and comprehensive combustion characteristic index B data are as follows:

[0083]

[0084] According to the above data and the formula in S3, continue to calculate the coal combustion coefficient K m = 15.08447, coal ignition temperature T m = 453.0317, coal burnout temperature t m = 568.8955, coal comprehensive combustion characteristic index B m = 3.7026;

[0085] Gasification fine slag combustion coefficient K n = 25.97, gasification fine slag ignition temperature T n = 625.0897, gasification fine slag burnout temperature t n = 693.2595, gasification fine slag comprehensive combustion characteristic index B n = 0.6991;

[0086] For different proportions of gasification fine slag and coal mixed samples, finally, the combustion characteristic data are calculated by using the method of the present invention as shown in Table a below:

[0087] Table a Combustion characteristic data calculated by the calculation method of the present invention

[0088]

[0089] For the above-mentioned gasification fine slag and coal mixed samples with different proportions, experimental measurements are carried out, and the true combustion characteristic data are as shown in Table b below:

[0090] Table b Combustion characteristic data of each group obtained by experiment

[0091]

[0092]

[0093] By comparing the data in Table A and Table B, it can be seen that for the calculation method provided by the present invention to calculate the combustion characteristics of the mixture of gasified fine slag and coal with different proportions, the calculation errors of the vast majority of data are within 5%, and the calculation errors of individual data may exceed 5% but not exceed 10%. This indicates that the calculation method of the present invention is an accurate and efficient calculation method for the combustion characteristics of the mixture of gasified fine slag and coal.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the present invention; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calculating the combustion characteristics of the mixed combustion of gasified fine slag and coal in different proportions, where the combustion characteristics include the ignition temperature T, burnout temperature t, and comprehensive combustion characteristic index B, and is characterized in that It includes the following steps: S1. Taking the moisture content M, volatile matter V, and fixed carbon FC as factors, select 10 representative gasification fine slags and 5 coals as experimental samples, conduct proximate analysis, ultimate analysis, calorific value Q, and combustion characteristics tests respectively to obtain different basic data of each gasification fine slag and coal, and establish a basic database of 10 gasification fine slags and 5 coals; S2. For the test sample obtained by mixing unknown types of gasification fine slag and unknown types of coal in different proportions, denote the coal in the test sample as m and the gasification fine slag as n, and obtain various basic data of coal m and gasification fine slag n according to the test method in S1; Calculate the sum of squares of the differences between the corresponding basic data of coal m and any coal in the basic database, and select the basic data of the coal in the corresponding basic database with the smallest calculated sum of squares as the target basic data of the coal; Calculate the sum of squares of the differences between the corresponding basic data of gasification fine slag n and any gasification fine slag in the basic database, and select the basic data of the gasification fine slag in the corresponding basic database with the smallest calculated sum of squares as the target basic data of the gasification fine slag; Taking the experimental samples providing the two sets of target basic data as the target basic samples, denote the target basic sample corresponding to coal m as sample α and the target basic sample corresponding to gasification fine slag n as sample β; S3. Calculate the combustion coefficient K of coal m based on the basic data of sample α and the basic data of coal m in the sample to be measured m , K m Specifically, it is the sum of the squares of the differences between the respective basic data values in sample α and the respective basic data values of coal m in the sample to be measured, each multiplied by the corresponding correction coefficient of each basic data value; Calculate the combustion coefficient K of gasification fine slag n based on the basic data of sample β and the basic data of gasification fine slag n in the sample to be measured n , K n Specifically, it is the sum of the squares of the differences between the respective basic data values of sample β and the respective basic data values of gasification fine slag n in the sample to be measured, each multiplied by the corresponding correction coefficient of each basic data value; S4. Calculate the combustion characteristics of coal m and gasification fine slag n respectively according to the following formulas, and the combustion characteristics include ignition temperature T, burnout temperature t, and comprehensive combustion characteristic index B: Ignition temperature of coal m where T α is the ignition temperature of sample α; Burnout temperature of coal m where t α is the burnout temperature of sample α; Comprehensive combustion characteristic index of coal m Where B α is the comprehensive combustion characteristic index of sample α; Ignition temperature of gasified fine slag where T β is the ignition temperature of sample β; Burnout temperature of gasified fine slag n In the formula, t β is the burnout temperature of sample β; Comprehensive combustion characteristic index of gasification fine slag Where B β is the comprehensive combustion characteristic index of sample β; S5. Let the mass fraction of coal m in the test sample be X, then for the test sample: The ignition temperature T = 1.22×T m ×X + 1.12×T n ×(1 - X); Burnout temperature t = 1.22 × t m × X + t n × (1 - X); Combustion characteristic index B = 0.68×B m ×X + 0.9×B n ×(1 - X).

2. The method for calculating the combustion characteristics of a mixture of gasified fine slag and coal with different proportions according to claim 1, characterized in that The proximate analysis includes the determination of moisture content M, ash content A, volatile matter V, and fixed carbon FC, and the ultimate analysis includes the determination of carbon element C, hydrogen element H, oxygen element O, nitrogen element N, and sulfur element S.

3. A method for calculating the combustion characteristics of a mixture of gasified fine slag and coal with different proportions as claimed in claim 2, characterized in that, In the said step S3, K m and K n The correction factors for each index used in the calculation are the same, specifically: the correction factor for water content M is 1, the correction factor for ash content A is 1, the correction factor for volatile matter V is 2, the correction factor for fixed carbon FC is 3, the correction factor for carbon element C is 1.5, the correction factor for hydrogen element H is 1.5, the correction factor for oxygen element O is 0.05, the correction factor for nitrogen element N is 0.02, the correction factor for sulfur element S is 0.02, and the correction factor for calorific value Q is 0.17.

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