Method for determining burn-off rate of pulverized coal in high-temperature reaction area by directly reading CO2 and CO concentrations through spectrum

Abstract

The invention discloses a method for determining the burn-off rate of pulverized coal in a high-temperature reaction area by directly reading CO2 and CO concentrations through a spectrum. According to the method, the concentration change of CO2 and CO in the combustion reaction process in a high-temperature reaction area is monitored in real time through a spectrum direct reading instrument, and a mathematical model between the burn-off rate and the CO2 and CO concentration is established in combination with factors such as the combustion temperature, the coal injection amount and the oxygen injection amount. According to the method, the burnout condition of the pulverized coal in the high-temperature reaction area can be reflected on line in real time, and the combustion efficiency of the pulverized coal can be accurately evaluated. Compared with a traditional burn-off rate measuring method, the method has high precision and high timeliness, effective data support can be provided for optimization control of the pulverized coal combustion process in the high-temperature reaction area, the pulverized coal combustion efficiency is further improved, and the energy loss in the combustion process is reduced.

Description

Technical Field

[0001] The present invention relates to, in particular, the technical field of monitoring and analysis of pulverized coal combustion process, and specifically to a method for real-time monitoring of the changes in the concentrations of CO2 and CO by using spectral direct-reading technology, and then calculating the burnout rate of pulverized coal in a high-temperature environment. Background Art

[0002] The pulverized coal combustion process is an important research topic in the energy-intensive industrial field and is widely applied to high-temperature environments such as blast furnace ironmaking and coal-fired power plants. In these fields, the burnout rate of pulverized coal not only directly determines the fuel utilization efficiency, but also affects the control of pollutant emissions and the operation stability of combustion equipment. However, due to the complex environment in the high-temperature furnace and limited measurement conditions, the direct measurement of the burnout rate of pulverized coal poses great technical challenges.

[0003] The current research field mainly relies on numerical simulation calculations or indirectly estimates the burnout rate of pulverized coal by analyzing the residual carbon content in blast furnace dust (such as petrographic analysis). However, due to the lack of direct experimental data support in the high-temperature combustion zone, the calculation results of these methods are difficult to accurately reflect the actual burnout state of pulverized coal during the combustion process, thus limiting the reliability and application promotion of the research results.

[0004] As the main products of pulverized coal combustion, the generation amounts of CO2 and CO are directly related to the burnout rate of pulverized coal. Therefore, real-time monitoring of the changes in the concentrations of CO2 and CO during the combustion process can provide an important basis for evaluating the burnout degree of pulverized coal. Spectral analysis technology has the characteristics of high sensitivity, fast response speed, non-contact measurement, etc., and can overcome many limitations of traditional measurement methods. Therefore, the technical personnel in this field are committed to developing a spectral direct-reading technology to realize the real-time monitoring of the concentrations of CO2 and CO, and combining the amount of pulverized coal participating in the reaction and the amount of oxygen, to calculate the burnout rate of pulverized coal in the high-temperature reaction zone. Summary of the Invention

[0005] To achieve the above object, the present invention provides a method for determining the burnout rate of pulverized coal in a high-temperature reaction zone by spectral direct-reading of CO2 and CO concentrations, which is characterized in that the calculation data includes the analysis data of the physical and chemical properties of pulverized coal in the high-temperature reaction zone; the number of moles of C element in the pulverized coal injected into the high-temperature reaction zone; the number of moles of O2 participating in the combustion reaction in the high-temperature reaction zone; the number of moles of C element consumed for the reaction to generate CO2; the number of moles of C element consumed for the reaction to generate CO; the total number of moles of C element consumed in the reaction and the burnout rate of pulverized coal; wherein, the analysis of the physical and chemical properties of pulverized coal in the high-temperature reaction zone is carried out using dry basis data, and the fixed carbon content, volatile matter content, and ash content are respectively denoted as FC daf , unit %, V daf , unit %, A daf, unit: %; the contents of carbon element C, hydrogen element H, nitrogen element N, sulfur element S and oxygen element O in the proximate analysis of pulverized coal are denoted as C, unit: %, H, unit: %, N, unit: %, S, unit: % and O, unit: % respectively; the high-temperature reaction zone refers to the area where the pulverized coal injected from the blast furnace tuyere undergoes a combustion reaction in the raceway.

[0006] Provide the mass m of the coal sample injected into the high-temperature reaction zone, unit: g; the C content in the proximate analysis parameters of the pulverized coal injected into the high-temperature reaction zone, unit: %; calculate the intermediate value of the number of moles N of element C in the pulverized coal participating in the combustion reaction in the high-temperature reaction zone, unit: mol; the specific calculation method is as follows:

[0007]

[0008] Provide the O2 pressure P1 in the oxygen lance, Pa; the oxygen injection volume V1 of the oxygen lance, m 3 ; the O2 temperature T1 in the oxygen lance, K; calculate the intermediate value of the number of moles N1 of O2 provided by the oxygen lance to the high-temperature reaction zone, mol; the specific calculation method is as follows:

[0009]

[0010] where R is 8.314 J / K;

[0011] Calculate the initial number of moles of O2 before the combustion reaction in the high-temperature reaction zone, unit: mol; the specific calculation method is as follows:

[0012]

[0013] Provide the volume fraction γ of the remaining O2 after the combustion reaction in the high-temperature reaction zone measured by spectral direct reading, unit: %; calculate the number of moles N4 of O2 participating in the combustion reaction in the high-temperature reaction zone, mol; the specific calculation method is as follows;

[0014]

[0015] Provide the volume fraction α of CO2 generated after the combustion reaction in the high-temperature reaction zone measured by spectral direct reading, unit: mol; calculate the volume fraction ψ1 of the CO2 generation amount after the combustion reaction in the high-temperature reaction zone relative to the total volume of CO2 and CO generation amounts, unit: %; the specific calculation method is as follows;

[0016]

[0017] Provide the volume fraction β of CO generated after the combustion reaction in the high-temperature reaction zone measured by spectral direct reading, mol; calculate the volume fraction ψ2 of the CO generation amount after the combustion reaction in the high-temperature reaction zone relative to the total volume of CO2 and CO generation amounts, %; the specific calculation method is as follows;

[0018]

[0019] Calculate the number of moles N5 of the C element content in the pulverized coal consumed to generate CO2 after complete combustion reaction with O2 in the high-temperature reaction zone, with the unit of mol; the specific calculation method is shown in the following formula;

[0020]

[0021] Calculate the number of moles N6 of the C element content in the pulverized coal consumed to generate CO after incomplete combustion reaction with O2 in the high-temperature reaction zone, in mol; the specific calculation method is shown in the following formula;

[0022]

[0023] Calculate the number of moles N7 of the C element content in the pulverized coal consumed to generate CO2 and CO after combustion reaction with O2 in the high-temperature reaction zone, in mol; the specific calculation method is shown in the following formula;

[0024]

[0025] Finally, the calculation method of the burnout rate of the pulverized coal is shown in the following formula;

[0026]

[0027] In the process of pulverized coal combustion of the present invention, by means of a spectral direct-reading instrument, the changes in the concentrations of CO2 and CO in the combustion gas are monitored in real time, and the burnout rate of the pulverized coal in the high-temperature reaction zone can be accurately judged. When abnormal changes in the concentrations of CO2 and CO are detected, it is possible to timely identify the situation of low burnout rate or incomplete combustion of the pulverized coal, and provide an early warning signal for optimizing the combustion process.

[0028] The following further describes the concept, specific structure and technical effects generated by the present invention to fully understand the purpose, features and effects of the present invention. Specific embodiments

[0029] The following introduces multiple preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0030] S1) Pretreat the pulverized coal for blast furnace injection;

[0031] S2) Analyze the physical and chemical parameters of the pulverized coal for blast furnace injection to obtain the fixed carbon content FC daf , volatile content V daf , ash content A daf content, as well as the contents of carbon element C, hydrogen element H, oxygen element O, nitrogen element N and sulfur element S;

[0032] S3) Determine the molar amount of carbon atoms per tuyere, the hot air injection volume per tuyere \(W\), and the oxygen enrichment injection volume per tuyere \(W\) based on the process parameters of the actual blast furnace, i.e., the pulverized coal injection volume per tuyere \(W\). PC Determine the molar amount of carbon atoms per tuyere, the hot air injection volume per tuyere \(W\), and the oxygen enrichment injection volume per tuyere \(W\). O2 Determine the molar amount of oxygen atoms per tuyere, and thus obtain the oxygen-to-carbon ratio \(A\). O / C ;

[0033] S4) Based on the parameters of the oxygen-enriched blast furnace simulation experiment device, i.e., the volume of the gas chamber, obtain the volume of the simulated coal injection carrier gas and the volume of the simulated hot air injection volume in the experiment. Calculate the experimental pulverized coal injection volume under the experimental conditions according to the oxygen-to-carbon ratio \(A\) and the volume of \(O_2\). O / C and the volume of \(O_2\).

[0034] S5) Conduct an experiment in the oxygen-enriched blast furnace simulation experiment device according to the experimental pulverized coal injection volume obtained in step S4), and calculate the combustion rate based on the results of the gas analyzer;

[0035] Calculate the combustion rate based on the results of the gas analyzer;

[0036] According to the embodiments of the present disclosure, the pretreatment of pulverized coal injection into the blast furnace described in S1) is carried out in accordance with the national standard GB / T474 - 2008 "Method for Preparation of Coal Samples".

[0037] According to the embodiments of the present disclosure, the analysis of the pulverized coal composition in S2) is carried out using dry basis data. The fixed carbon content, volatile matter content, and ash content are analyzed in accordance with the national standard GB / T212 - 2008 "Proximate Analysis of Coal", and are denoted as FC daf , %, V daf , %, A daf , %;

[0038] According to the embodiments of the present disclosure, for the elemental analysis of the pulverized coal in S2), the carbon element C and hydrogen element H contents are analyzed in accordance with the national standard GB / T212 - 2008 "Determination of Carbon and Hydrogen in Coal", the nitrogen element N content is analyzed in accordance with the national standard GB / T19227 - 2008 "Determination of Nitrogen in Coal", the sulfur element S content is analyzed in accordance with the national standard GB / T214 - 2007 "Determination of Total Sulfur in Coal", and the oxygen element O content is calculated by the subtraction method, and are denoted as C, %, H, %, N, %, S, %, and O, % respectively;

[0039] According to the embodiments of the present disclosure, for the process parameters of the actual blast furnace described in S3), provide the pulverized coal injection volume per tuyere \(W\) PC , kg / tHM, the hot air injection volume per tuyere \(W\), kg / tHM, and the oxygen enrichment injection volume per tuyere \(W\) O2 , kg / tHM

[0040] Calculate the molar amount of carbon atoms per tuyere \(N\) C, mol / S; The specific calculation method is shown in formula (1)

[0041]

[0042] Calculate the molar amount of oxygen atoms N at a single tuyere O , mol / S; The specific calculation method is shown in formula (2)

[0043]

[0044] Calculate the oxygen-carbon atom ratio A of the process parameters of the actual blast furnace O / C ,; The specific calculation method is shown in formula (3)

[0045]

[0046] According to the parameters of the oxygen-enriched blast furnace simulation experiment device described in S4) of the present disclosure, provide the volume V1, mL, oxygen pressure P1, pa, and oxygen temperature T1, K of the oxygen gas chamber in the simulated coal injection carrier gas system;

[0047] Calculate the number of moles of O2, N1, mol, provided by the oxygen injection lance to the high-temperature reaction zone; the specific calculation method is shown in formula (4);

[0048]

[0049] According to the parameters of the oxygen-enriched blast furnace simulation experiment device described in S4) of the present disclosure, provide the volume V2, mL, oxygen pressure P2, pa, and oxygen temperature T2, K of the oxygen gas chamber in the simulated hot blast stove air supply system;

[0050] Calculate the number of moles of O2, N2, mol, provided by the oxygen injection lance to the high-temperature reaction zone; the specific calculation method is shown in formula (5);

[0051]

[0052] Calculate the initial number of moles of O2, N3, mol, before the combustion reaction in the experimental high-temperature reaction zone; the specific calculation method is shown in formula (6);

[0053]

[0054] Calculate the number of moles of O atoms N before the combustion reaction in the experimental high-temperature reaction zone o , mol; the specific calculation method is shown in formula (7);

[0055]

[0056] According to the oxygen-carbon atom ratio A of the process parameters of the actual blast furnace O / C , calculate the number of moles of C atoms N in the pulverized coal required for the combustion reaction in the experimental high-temperature reaction zonec , mol; The specific calculation method is shown in Formula (8);

[0057]

[0058] According to the number of moles of C atoms N in pulverized coal required for the combustion reaction in the high-temperature reaction zone of the experiment, c , mol; Calculate the mass m, g of pulverized coal required for the combustion reaction in the high-temperature reaction zone of the experiment; The specific calculation method is shown in Formula (9);

[0059]

[0060] According to the embodiment of the present disclosure, the experimental pulverized coal injection amount described in S5) is experimented in the oxygen-enriched blast furnace simulation experimental device to provide the number of moles N of C atoms in the pulverized coal participating in the combustion reaction in the high-temperature reaction zone, mol; The specific calculation method is shown in Formula (10);

[0061]

[0062] According to the embodiment of the present disclosure, the experimental pulverized coal injection amount described in S5) is experimented in the oxygen-enriched blast furnace simulation experimental device to provide the O2 pressure P1, pa in the oxygen injection lance; the oxygen injection volume V1, Nm 3 / t; the O2 temperature T1 in the oxygen injection lance;

[0063] Calculate the number of moles N1 of O2 provided by the intermediate oxygen injection lance to the high-temperature reaction zone, mol. The specific calculation method is shown in Formula (11);

[0064]

[0065] where R is 8.314 J / K.

[0066] According to the embodiment of the present disclosure, the experimental pulverized coal injection amount described in S5) is experimented in the oxygen-enriched blast furnace simulation experimental device to provide the O2 pressure P2, pa in the hot blast stove air supply system; the air supply volume V2, Nm 3 / t; the O2 temperature T2 in the hot blast stove air supply system;

[0067] Calculate the number of moles N2 of O2 provided by the intermediate hot blast stove air supply system to the high-temperature reaction zone, mol. The specific calculation method is shown in Formula (12);

[0068]

[0069] Calculate the initial number of moles of O2 before the combustion reaction in the high-temperature reaction zone, mol. The specific calculation method is shown in Formula (13);

[0070]

[0071] According to an embodiment of the present disclosure, the amount of pulverized coal injected in the experiment described in S5) is experimented in an oxygen-enriched blast furnace simulation experimental device to provide the volume fraction γ, % of the remaining O2 after the combustion reaction in the high-temperature reaction zone;

[0072] Calculate the number of moles N4, mol of O2 participating in the combustion reaction in the high-temperature reaction zone. The specific calculation method is shown in formula (14);

[0073]

[0074] According to an embodiment of the present disclosure, the amount of pulverized coal injected in the experiment described in S5) is experimented in an oxygen-enriched blast furnace simulation experimental device to provide the volume fraction α, mol of CO2 generated after the combustion reaction in the high-temperature reaction zone;

[0075] According to an embodiment of the present disclosure, the amount of pulverized coal injected in the experiment described in S5) is experimented in an oxygen-enriched blast furnace simulation experimental device to provide the volume fraction β, mol of CO generated after the combustion reaction in the high-temperature reaction zone;

[0076] Calculate the volume percentage ψ1, % of the CO2 generation amount relative to the total generation amount of CO2 and CO after the combustion reaction in the high-temperature reaction zone; the specific calculation method is shown in formula (15);

[0077]

[0078] Calculate the volume percentage ψ2, % of the CO generation amount relative to the total generation amount of CO2 and CO after the combustion reaction in the high-temperature reaction zone; the specific calculation method is shown in formula (16);

[0079]

[0080] Calculate the number of moles N5, mol of the C element content in the pulverized coal consumed to generate CO2 after the complete combustion reaction with O2 in the high-temperature reaction zone; the specific calculation method is shown in formula (17);

[0081]

[0082] Calculate the number of moles N6, mol of the C element content in the pulverized coal consumed to generate CO after the incomplete combustion reaction with O2 in the high-temperature reaction zone; the specific calculation method is shown in formula (18);

[0083]

[0084] Calculate the number of moles N7, mol of the C element content in the pulverized coal consumed to generate CO2 and CO after the combustion reaction with O2 in the high-temperature reaction zone; the specific calculation method is shown in formula (19);

[0085]

[0086] Calculate the burnout rate η of pulverized coal, and the specific calculation method can be found in formula (20);

[0087]

[0088] Example 1

[0089] Select the measured values of the component analysis and elemental analysis of the injected pulverized coal as shown in Table 1:

[0090] Table 1 Component analysis and elemental analysis of pulverized coal injected into blast furnace, %

[0091]

[0092] The process parameters of the actual blast furnace are shown in Table 2:

[0093] Table 2 Blast furnace process parameters

[0094]

[0095] Substitute the data in Table 1 and Table 2 into the formula to solve the combustion rate of pulverized coal injected into the blast furnace.

[0096] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should fall within the protection scope determined by the claims.

Claims

1. A method for determining the burnout rate of pulverized coal in a high-temperature reaction zone by directly reading CO2 and CO concentrations, characterized in that: The calculation data include the physicochemical characteristics analysis data of coal powder in the high temperature reaction zone; the molar number of C element in the coal powder injected into the high temperature reaction zone; the molar number of O2 participating in the combustion reaction in the high temperature reaction zone; the molar number of C element consumed by the reaction to generate CO2; the molar number of C element consumed by the reaction to generate CO; the total molar number of C element consumed by the reaction and the coal powder burnout rate; among them, the physicochemical characteristics analysis of coal powder in the high temperature reaction zone is carried out using dry basis data, and the fixed carbon content, volatile matter content, and ash content are recorded as FC respectively. daf , unit %, V daf , unit %, A daf , unit %; the carbon element C, hydrogen element H, nitrogen element N, sulfur element S content and oxygen element O content in the elemental analysis of pulverized coal are recorded as C, unit %, H, unit %, N, unit %, S, unit % and O, unit % respectively; Provide the mass m of the coal sample injected into the high temperature reaction zone, in g; the C content in the elemental analysis parameters of the coal powder injected into the high temperature reaction zone, in %; calculate the molar number N of the C element in the coal powder participating in the combustion reaction in the intermediate high temperature reaction zone, in mol; the specific calculation method is shown in the following formula: Provide O2 pressure in oxygen spray gun P1, pa; oxygen spray gun spray volume V1, m 3 ; O2 temperature in the oxygen spray gun T1, K; calculate the intermediate value of the oxygen spray gun to provide O2 mole number N1, mol in the high temperature reaction zone; the specific calculation method is shown in the following formula: Where R is 8.314 J / K; Calculate the initial molar number of O2 before the combustion reaction in the high-temperature reaction zone, in mol; see the following formula for the specific calculation method: Provide the spectral direct reading of the residual O2 volume fraction γ after the combustion reaction in the high-temperature reaction zone, in units of %; calculate the number of O2 moles N4, mol, participating in the combustion reaction in the high-temperature reaction zone; see the following formula for the specific calculation method; Provide the volume fraction α of CO2 generated after the combustion reaction in the high-temperature reaction zone by direct spectral reading, in mol; calculate the volume proportion ψ1 of the amount of CO2 generated after the combustion reaction in the high-temperature reaction zone relative to the total amount of CO2 and CO generated, in %. See the following formula for the specific calculation method; Provide the volume fraction β, mol of CO generated after the combustion reaction in the high-temperature reaction zone by direct spectral reading; calculate the volume proportion ψ2, % of the amount of CO generated after the combustion reaction in the high-temperature reaction zone relative to the total amount of CO2 and CO generated; refer to the following formula for the specific calculation method; Calculate the molar number N5 of the C element content in the pulverized coal consumed to generate CO2 after complete combustion reaction with O2 in the high-temperature reaction zone, in mol; the specific calculation method is shown in the following formula; Calculate the molar number N6, mol of the C element content in the pulverized coal consumed to generate CO after the incomplete combustion reaction with O2 in the high-temperature reaction zone; the specific calculation method is shown in the following formula; Calculate the molar number N7, mol of the C element content in the pulverized coal consumed by the combustion reaction with O2 to generate CO2 and CO in the high-temperature reaction zone; the specific calculation method is shown in the following formula; Finally, the coal powder burnout rate is calculated according to the following formula:

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