Method, device and terminal for calculating NOx generation concentration of coal-fired boiler

Abstract

The invention discloses a coal-fired boiler NOx generation concentration calculation method and device and a terminal.The technical scheme includes the steps that firstly, according to structure information of a coal-fired boiler, a combustion area of the coal-fired boiler is divided into a plurality of sub-combustion areas; area combustion parameters of all the sub-combustion areas are obtained; according to the regional combustion parameters, combining with a preset NOx concentration calculation formula, and determining the predicted concentration of NOx generated by the coal-fired boiler, according to the scheme, starting from the generation mechanism of NOx of the coal-fired boiler, the calculation formula and the implementation method of the NOx generation concentration are provided, better adaptability to various operation conditions of the coal-fired boiler is achieved, and the method is suitable for popularization and application. The NOx generation concentration of the coal-fired boiler can be well predicted online in real time, the method is used for precise ammonia spraying control of a boiler denitration system, and the economical efficiency and safety of a unit are improved.

Description

Technical Field

[0001] This application relates to the field of thermal power technology, and particularly to a method, device and terminal for calculating the NO x generation concentration of a coal-fired boiler. Background Art

[0002] At present, coal-fired boilers basically adopt low-nitrogen combustion methods and are equipped with selective catalytic reduction (SCR) denitration systems to achieve NO x ultra-low emissions. Continuous emission monitoring systems (CEMS) are configured at the inlet and outlet of the SCR denitration system, which can continuously monitor the NO x concentration and O2 concentration entering the SCR denitration system, etc. This NO x concentration is the NO x generation concentration of the coal-fired boiler, and the ammonia injection control of the SCR denitration system is also based on this NO x concentration. However, since the current monitoring method is to extract flue gas into an analyzer and then measure the NO x concentration by infrared method or chemiluminescence method, there is a large lag relative to the ammonia injection moment, and the ammonia-nitrogen cannot be accurately matched, so the precise ammonia injection control of the denitration system cannot be truly achieved, which is likely to cause a series of problems such as air preheater blockage and reduction of denitration efficiency, seriously affecting the safe operation of the boiler unit. Summary of the Invention

[0003] This application provides a method, device and terminal for calculating the NO x generation concentration of a coal-fired boiler, which is used to solve the safety problems existing in the existing coal-fired boiler units.

[0004] To solve the above technical problems, in the first aspect of this application, a method for calculating the NOx generation concentration of a coal-fired boiler is provided, including:

[0005] Dividing the combustion area of the coal-fired boiler into multiple sub-combustion areas according to the structural information of the coal-fired boiler;

[0006] Obtaining the regional combustion parameters of each sub-combustion area, where the regional combustion parameters include: coal combustion parameters and excess air coefficient, and the coal combustion parameters include: coal consumption, coal calorific value and comprehensive coal quality parameters;

[0007] According to the regional combustion parameters, combining with a preset NO x concentration calculation formula, determining the predicted NO x concentration generated by the coal-fired boiler.

[0008] Preferably, the NO x concentration calculation formula is specifically:

[0009]

[0010] In the formula, m is the number of sub - combustion regions, K and B are coefficients, n is an exponent, G is the coal combustion amount in each sub - combustion region, Qnet is the calorific value of the coal in each sub - combustion region, MZ is the comprehensive coal quality parameter in each sub - combustion region, α is the excess air coefficient in each sub - combustion region, P is the unit power, Pe is the rated power of the unit, Qy is the flue gas volume under standard conditions before the boiler denitration system, and μ NOx is the predicted concentration of NO generated by the boiler combustion, and i is the number of the sub - combustion region. x

[0011]

[0011] Preferably, the method for obtaining the coal combustion parameters includes:

[0012] Measuring the coal combustion amount in each sub - combustion region through a preset on - line coal amount monitoring module, or calculating the coal combustion amount in each sub - combustion region by equally dividing the total coal combustion amount of each layer according to the burner layer layout information of the coal - fired boiler;

[0013] Measuring the calorific value of the coal in each burner layer through a preset on - line coal quality monitoring module, or calculating the calorific value of the coal in each sub - combustion region by the heat balance calculation method;

[0014] Measuring the nitrogen content and volatile matter of each burner layer through a preset on - line coal quality monitoring module, and determining the comprehensive coal quality parameter of each sub - combustion region according to the nitrogen content and the volatile matter, or calculating the moisture parameter of each burner layer by the heat balance calculation method, and then determining the volatile matter through a preset volatile matter conversion relation formula, and determining the comprehensive coal quality parameter of each sub - combustion region according to the volatile matter.

[0015] Preferably, the method for obtaining the excess air coefficient includes:

[0016] Constructing an excess air correction coefficient calculation formula according to the total primary air volume, total secondary air volume of the coal - fired boiler and the on - line measured oxygen content at the denitration inlet;

[0017] Calculating the excess air coefficient of each sub - combustion region respectively according to the calculated excess air correction coefficient and the air volume flow relationship of each sub - combustion region.

[0018] Preferably, the method for dividing the combustion region of the coal - fired boiler into multiple sub - combustion regions according to the structure information of the coal - fired boiler includes:

[0019] According to the structure information of the coal - fired boiler, taking a single combustion nozzle as the smallest division unit, and dividing the combustion region of the coal - fired boiler into multiple sub - combustion regions along the combustion process direction.

[0020] Preferably, it further includes:

[0021] Determining NO xMeasure the time delay difference between the measured concentration and the boiler operating parameters, and linearly fit the boiler operating parameters with the NO x measured concentrations at different time delays to obtain the correlation coefficients at different time delays.

[0022] Determine the optimal time delay based on the maximum value of the correlation coefficient, and shift the NO x measured concentration according to the optimal time delay to align the time of the NO x measured concentration and the boiler operating parameters.

[0023] Preferably, the calculation formula for the flue gas volume under standard conditions is:

[0024]

[0025] In the formula, Q1 and Q2 are the total primary air volume and the total secondary air volume of the boiler respectively, Aar is the ash content of the coal entering the boiler, and Gj is the coal consumption of the jth layer of burners or coal mills.

[0026] Preferably, it further includes:

[0027] Collect multiple groups of boiler operation data, establish multiple groups of non-linear equations, and then use the least squares method to solve the non-linear equations to determine the values of each constant coefficient and exponent in the NO x concentration calculation formula according to the solution results.

[0028] Meanwhile, a second aspect of the present application provides a device for calculating the NO x generation concentration of a coal-fired boiler, including:

[0029] A region division unit for dividing the combustion region of the coal-fired boiler into multiple sub-combustion regions according to the structural information of the coal-fired boiler;

[0030] A combustion parameter acquisition unit for acquiring the regional combustion parameters of each sub-combustion region;

[0031] A concentration prediction unit for determining the predicted NO x concentration generated by the coal-fired boiler according to the regional combustion parameters and in combination with a preset NO x concentration calculation formula.

[0032] A third aspect of the present application provides a terminal for calculating the NO x generation concentration of a coal-fired boiler, including: a memory and a processor;

[0033] The memory is used to store program code, and the program code is used to implement a method for calculating the NO x generation concentration of a coal-fired boiler provided in the first aspect of the present application;

[0034] The processor is used to read and execute the program code.

[0035] As can be seen from the above technical solutions, the present application has the following advantages:

[0036] The technical solution provided by the present application first divides the combustion area of the coal-fired boiler into multiple sub-combustion areas according to the structural information of the coal-fired boiler; obtains the regional combustion parameters of each sub-combustion area; and according to the regional combustion parameters, combines a preset NO x concentration calculation formula to determine the predicted concentration of NO generated by the coal-fired boiler. This solution starts from the generation mechanism of NO in the coal-fired boiler, provides a calculation formula and implementation method for the generated concentration of NO, has better adaptability to various operating conditions of the coal-fired boiler, and can preferably predict the generated concentration of NO in the coal-fired boiler online in real time, and is used for precise ammonia injection control of the boiler denitration system, improving the economy and safety of the unit. x in the coal-fired boiler, x and provides x a calculation formula for the generated concentration of NO. x It has better adaptability to various operating conditions of the coal-fired boiler, can preferably predict the generated concentration of NO in the coal-fired boiler online in real time, and is used for precise ammonia injection control of the boiler denitration system, improving the economy and safety of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0038] Figure 1 FIG. is a schematic flow chart of an embodiment of a method for calculating the generated concentration of NO in a coal-fired boiler provided by the present application. x

[0039] Figure 2 FIG. is a schematic layout diagram of a boiler combustion system.

[0040] Figure 3 FIG. is a schematic diagram of the delay time relationship between the boiler operating parameters and the NO concentration measured at the inlet of the denitration system. x

[0041] Figure 4 FIG. is a schematic diagram of the delay time series of NO concentration. x

[0042] Figure 5 FIG. is a curve graph showing the change relationship between the delay time and the correlation coefficient.

[0043] Figure 6 FIG. is a comparison schematic diagram of the predicted result and the actual measurement result obtained by the method for calculating the generated concentration of NO in a coal-fired boiler provided by the present application. x ​​​​

[0044] Figure 7 A NO for this application x Schematic structural diagram of an embodiment of a generation concentration calculation device.

[0045] Figure 8 A NO for this application x Schematic structural diagram of an embodiment of a generation concentration calculation terminal. Detailed implementation manner

[0046] An embodiment of this application provides a NO for a coal-fired boiler x Generation concentration calculation method, device and terminal, which are used to solve the safety problems existing in existing coal-fired boiler units.

[0047] In order to make the invention purpose, features and advantages of this application more obvious and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the embodiments described below are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0048] First is a detailed description of an embodiment of a NO generation concentration calculation method provided by this application, which is specifically as follows: x Please refer to

[0049] Refer to Figure 1 An NO generation concentration calculation method provided by an embodiment of this application includes: x Step 101: Divide the combustion area of the coal-fired boiler into multiple sub-combustion areas according to the structural information of the coal-fired boiler.

[0050] Step 102: Obtain the regional combustion parameters of each sub-combustion area.

[0051] Step 103: According to the regional combustion parameters, combine with a preset NO

[0052] concentration calculation formula to determine the predicted concentration of NO generated by the coal-fired boiler. x concentration x predicted concentration.

[0053] It should be noted that according to the method provided in this embodiment, first, according to the structural information of the coal-fired boiler, specifically including: the arrangement of combustion nozzles and the distribution of on-line measuring points, the boiler combustion area is divided into multiple sub-combustion areas.

[0054] Then, based on the divided sub-combustion regions, obtain the regional combustion parameters of each sub-combustion region. Among them, the regional combustion parameters include: coal combustion parameters and excess air coefficient. The coal combustion parameters include: coal consumption, coal calorific value, and comprehensive coal quality parameters. Then, according to the above regional combustion parameters, combined with a preset NO x concentration calculation formula, determine the predicted NO x concentration generated by the coal-fired boiler;

[0055] Among them, the NO x concentration calculation formula is specifically:

[0056] (1)

[0057] In the formula, m is the number of sub-combustion regions, K and B are coefficients, n is an exponent, G is the coal consumption of each sub-combustion region, Qnet is the coal calorific value of each sub-combustion region, MZ is the comprehensive coal quality parameter of each sub-combustion region, α is the excess air coefficient of each sub-combustion region, P is the unit power, Pe is the rated unit power, Qy is the flue gas volume at standard conditions before the boiler denitration system, μ NOx is the predicted NO x concentration generated by boiler combustion, and i is the number of the sub-combustion region.

[0058] Furthermore, according to the structural information of the coal-fired boiler, dividing the combustion region of the coal-fired boiler into multiple sub-combustion regions includes:

[0059] According to the structural information of the coal-fired boiler, taking a single combustion nozzle as the smallest division unit, along the combustion process direction, divide the combustion region of the coal-fired boiler into multiple sub-combustion regions.

[0060] It should be noted that the division of sub-combustion regions is based on a single combustion nozzle, divided along the combustion process direction, and considering the staged combustion of primary air, secondary air, and overfire air. Taking a front and rear wall opposed fired boiler as an example, its combustion system layout is as Figure 2 shown. There are 3 layers of burners and 1 layer of overfire air arranged on the front wall and the rear wall respectively. Each layer of burners has 6 combustion nozzles, and each combustion nozzle is equipped with primary air and secondary air respectively. Then, the sub-combustion regions are divided into 84 in total, including 42 on the front wall and 42 on the rear wall.

[0061] When it is impossible to obtain the coal quantity and the primary and secondary air volumes of each combustion nozzle separately, the division of sub-combustion regions is based on the burner layer. It is equivalent to combining the 6 nozzles of the same layer of burners. Then, the actual number of sub-combustion regions is 14, including 7 on the front wall and 7 on the rear wall.

[0062] More specifically, for the coal combustion parameters in the NO x concentration calculation formula, the acquisition method includes:

[0063] Through the preset on-line coal quantity monitoring module, measure the coal quantity of each sub-combustion area, or according to the burner layer layout information of the coal-fired boiler, evenly divide and calculate based on the total coal quantity of each layer to obtain the coal quantity of each sub-combustion area;

[0064] Through the preset on-line coal quality monitoring module, measure the calorific value of the coal for each burner layer, or calculate the calorific value of the coal in each sub-combustion area through the heat balance calculation method;

[0065] Through the preset on-line coal quality monitoring module, measure the nitrogen content and volatile matter of each burner layer, and determine the comprehensive coal quality parameters of each sub-combustion area according to the nitrogen content and volatile matter, or calculate the moisture parameter of each burner layer through the heat balance calculation method, and then determine the volatile matter through the preset volatile matter conversion relationship formula, and determine the comprehensive coal quality parameters of each sub-combustion area according to the volatile matter.

[0066] It should be noted that the coal combustion parameters of each sub-combustion area Consist of three parts, namely the coal quantity G, the calorific value of coal Qnet and the comprehensive coal quality parameter MZ in the sub-combustion area. Among them, Qnet and MZ are the same for the 6 nozzles of each layer of burners, that is, corresponding to the burner layer or the coal mill, and are Qnetj and MZj respectively, where j = A, B, C, D, E, F.

[0067] 1) Determination of Qnet:

[0068] When each coal mill of the boiler is equipped with an on-line measurement system for the coal quality of the coal entering the furnace, Qnetj takes the on-line measurement value Qnetj,cl of each coal mill;

[0069] When each coal mill of the boiler is not equipped with an on-line measurement system for the coal quality of the coal entering the furnace, but the coal conveyor belt of the boiler is equipped with an on-line measurement system for the coal quality of the coal entering the furnace, then the calorific values of the coal for the 6 coal mills are equal, and all take the on-line measurement value Qnet,cl of the coal conveyor belt of the boiler, that is:

[0070] Qnetj = Qnet,cl j = A, B, C, D, E, F (2)

[0071] When the boiler is not equipped with an on-line measurement system for the coal quality of the coal entering the furnace, then the calorific value of the coal entering the furnace Qnet,js is obtained according to the heat balance calculation of the boiler unit, and it is the same for each burner layer or sub-burner area, as shown in formula (3). The specific calculation method will not be repeated here. Further, in the scenario where the boiler is not equipped with an on-line measurement system for the coal quality of the coal entering the furnace, in addition to the above-preferred heat balance calculation method, the calorific value of the coal entering the furnace Qnet,js can also be obtained through the method of building a model based on operating parameters.

[0072] Qnetj = Qnet,js j = A, B, C, D, E, F (3)

[0073] 2) Determination of MZ:

[0074] MZ is the comprehensive coal quality parameter affecting boiler NO x Generated. According to the research on the NO x Generation mechanism, MZ mainly includes nitrogen Nar, volatile matter Var, etc., and corresponds to the burner layer or the coal mill.

[0075] When each coal mill of the boiler is equipped with an on-line measurement system for the coal quality entering the furnace, the nitrogen Narj and volatile matter Varj take the on-line measurement values Narj,cl and Varj,cl of each coal mill respectively, where j = A, B, C, D, E, F;

[0076] When each coal mill of the boiler is not equipped with an on-line measurement system for the coal quality entering the furnace, but the on-line measurement system for the coal quality entering the furnace is equipped on the coal feeding belt of the boiler, then the coal quality parameters of the 6 coal mills are equal and all take the on-line measurement values Nar,cl and Var,cl of the coal feeding belt of the boiler. That is:

[0077] Narj = Nar,cl, j = A, B, C, D, E, F (4)

[0078] Varj = Var,cl, j = A, B, C, D, E, F (5)

[0079] When the boiler is not equipped with an on-line measurement system for the coal quality entering the furnace, then first calculate the coal quality moisture Mtj,js according to the heat balance of the boiler coal mill, and then calculate the Varj,js of the coal quality entering the furnace through big data analysis and modeling of the coal quality entering the furnace, as shown in formula (6). The specific calculation method will not be repeated.

[0080] Varj = f1(Mtj,js) (6)

[0081] An application example of the f1 function is:

[0082] Mtj,js ≤ 7.0, Varj = -0.353 Mtj,js 2 +4.1 Mtj,js - 1.17

[0083] 7.0 < Mtj,js ≤ 10.0, Varj = -0.67 Mtj,js 2 +16.1 Mtj,js - 69.6

[0084] 10.0 < Mtj,js, Varj = -0.05 Mtj,js 2 +1.65 Mtj,js + 11.8

[0085] Correlation coefficient R of the above modeling formula 2 ≈0.2 - 0.7

[0086] When using the calculation method, the coal quality Nar of each burner layer or mill cannot be obtained and is ignored during the calculation.

[0087] When both nitrogen Narj and volatile matter Varj can be obtained, the calculation formula for MZj is:

[0088] MZj = P1j Varj m1 +P2j Narj m2 j = A, B, C, D, E, F (7)

[0089] Where: P1j and P2j are the weight coefficients of coal quality parameters, and m1 and m2 are the exponents of coal quality parameters. They can be solved by collecting multiple sets of operating data to establish a non - linear equation system and using solution algorithms such as the least - squares method.

[0090] When only considering the volatile matter Var for the comprehensive coal quality parameter, formula (1) becomes:

[0091] (8)

[0092] 3) Determination of the coal combustion amount G in the sub - combustion area:

[0093] When there are online measurement data for the coal amount entering the furnace of each combustion nozzle, such as an online wind - powder measurement system installed on each powder pipe, the measured value of the coal amount entering the furnace Gjh,cl of each nozzle can be obtained, where j = A, B, C, D, E, F, h = 1, 2, 3, 4, 5, 6; otherwise, take 1 / 6 of the coal amount entering the furnace Gj of each burner layer or mill, then the coal amount entering the furnace of each nozzle is:

[0094] Gjh = Gjh,cl or Gjh = Gj / 6;

[0095] The calculation method of coal combustion parameters in the sub - combustion area. Specifically, the calculation method of coal combustion parameters in sub - combustion area i is the sum of the coal combustion parameters of each nozzle at the same column position in front of area i in the reverse flue gas flow direction. Its general calculation formula is:

[0096] (9)

[0097] Where, j is the burner layer or mill, h is the nozzle column number of the same burner layer, Gjh is the coal combustion amount of the h - th column nozzle of the j - th burner layer; Qnetj is the calorific value of the coal burned by the j - th burner layer; MZj is the comprehensive coal quality parameter of the j - th burner layer.

[0098] Taking the sub-combustion zones from 1 to 7 as an example and only considering the volatile matter Var, we can have:

[0099] Coal combustion parameters for the 1st and 2nd sub-combustion zones:

[0100] ( ) 1,2 = GC1 QnetC (P1C VarC m1 ) (10)

[0101] Coal combustion parameters for the 3rd and 4th sub-combustion zones:

[0102] ( ) 3,4 = GC1 QnetC (P1C VarC m1 ) + GB1 QnetB (P1B VarB m1 ) (11)

[0103] Coal combustion parameters for the 5th and 6th sub-combustion zones:

[0104]

[0105] Coal combustion parameters for the 7th sub-combustion zone:

[0106] ( )7 = ( ) 5,6

[0107] The coal feed quantity Gj for each layer of burners or coal mills into the furnace is calculated according to the primary air duct resistance method or by modeling based on the operating parameters of the coal mills. The specific calculation method will not be elaborated here.

[0108] Furthermore, for the excess air coefficient in the NO x concentration calculation formula, the acquisition methods include:

[0109] Construct an excess air correction coefficient calculation formula based on the total primary air volume, total secondary air volume of the coal-fired boiler, and the online measured oxygen content at the denitration inlet;

[0110] According to the calculated excess air correction coefficient and combined with the air volume flow relationship of each sub-combustion zone, calculate the excess air coefficient of each sub-combustion zone respectively.

[0111] It should be noted that, first, according to the total primary air volume, total secondary air volume of the coal-fired boiler, and the online measured oxygen content at the denitration inlet, a calculation formula for the excess air correction coefficient is constructed to calculate the excess air correction coefficient. Then, based on the calculated excess air correction coefficient and combined with the air volume flow relationship in each sub-combustion area, the excess air coefficient of each sub-combustion area is calculated respectively.

[0112] More specifically, the correction coefficient Kxz of the excess air coefficient is determined

[0113] (14)

[0114] In the formula: O 2A 、O 2B are the online measured oxygen contents on the A and B sides at the inlet of the boiler SCR denitration system or air preheater, %;

[0115] Q1 is the total primary air volume of the boiler, t / h;

[0116]

[0117] Among them, QA1, QB1, QC1, QD1, QE1, QF1 are the online measured values of the primary air volume of mills A to F respectively, t / h.

[0118] Q2 is the online measured value of the total secondary air volume of the boiler, t / h;

[0119] K0 is the theoretical air volume per unit calorific value, which is the statistical average value of the common coal types used in the boiler, t / h / MJ. For example, for a certain bituminous coal boiler, K0 is about 0.34 t / h / MJ.

[0120] 2) The excess air coefficient of the sub-combustion area, and its general calculation formula is as follows:

[0121] (15)

[0122] In the formula, is the sum of the primary and secondary air volumes of each nozzle in the hth row in front of the i area in the reverse flue gas flow direction; K0 is the theoretical air volume per unit calorific value; is the sum of the heat entering the boiler of each nozzle in the hth row in front of the i area in the reverse flue gas flow direction.

[0123] More specifically, taking the Figure 2 shown structure as an example, the excess air coefficient of the 1st sub-combustion area:

[0124] (16)

[0125] Where: QC11 is the primary air volume of the #1 nozzle in the C burner layer, an on-line measured value, t / h. When there is no on-line measured value, QC11 is taken as GC1 / 6, and GC1 is the primary air volume of the C coal mill.

[0126] GC1 is the coal feed amount into the furnace of the #1 nozzle in the C burner layer, taking the on-line measured value GC1,cl; when there is no on-line measured value, GC1 = GC / 6, and GC is the coal feed amount into the furnace of the C coal mill or the burner layer, t / h;

[0127] QnetC is the calorific value of the coal quality of the C coal mill, MJ / kg.

[0128] 0.001 is to prevent the denominator from being 0 when the C coal mill stops running.

[0129] Excess air coefficient in the secondary combustion area:

[0130] (17)

[0131] Where: QC21 is the secondary air volume of the #1 nozzle in the C burner layer, t / h; obtained through on-line measurement or calculation, and the calculation method is as follows:

[0132] (18)

[0133] Where: VC1 is the opening of the secondary air damper of the #1 nozzle in the C burner layer, %; Vr is the opening of each secondary air damper of the boiler, including the A~F burner layers, the front wall overfire air layer, and the rear wall overfire air layer, %; s is an exponent, determined according to the damper resistance characteristics, and s can be taken as 0.555.

[0134] Excess air coefficient in the third combustion area:

[0135] (19)

[0136] Where: QB11 is the primary air volume of the #1 nozzle in the B burner layer, t / h;

[0137] GB1 is the coal feed amount into the furnace of the #1 nozzle in the B burner layer, t / h, and the acquisition method is the same as before.

[0138] QnetB is the calorific value of the coal quality of the B coal mill, MJ / kg.

[0139] Excess air coefficient in the fourth combustion area:

[0140] (20)

[0141] Where: QB21 is the secondary air volume of the #1 nozzle in the B burner layer, t / h, and the acquisition method is the same as before.

[0142] Excess air coefficient in the fifth combustion area:

[0143] (21)

[0144] Where: QA11 is the primary air volume of nozzle #1 in burner layer A, t / h, and the acquisition method is the same as before.

[0145] GA1 is the coal quantity fed into the furnace of nozzle #1 in burner layer A, t / h, and the acquisition method is the same as before.

[0146] QnetA is the calorific value of the coal quality of mill A, MJ / kg.

[0147] Excess air coefficient in the 6th sub-combustion area:

[0148] (22)

[0149] Where: QA21 is the secondary air volume of nozzle #1 in burner layer A, t / h, and the acquisition method is the same as before.

[0150] Excess air coefficient in the 7th sub-combustion area:

[0151] (23)

[0152] Where: QQ21 is the secondary air volume of nozzle #1 in the front wall overfire air layer, t / h, and the acquisition method is the same as before.

[0153] More specifically, regarding the determination of the standard state flue gas volume Qy parameter:

[0154] (24)

[0155] Where: Aar is the ash content of the coal fed into the boiler, %; it can be calculated from the calorific value Qnet,js and moisture Mt of the coal fed into the furnace.

[0156] Aar = f2(Qnet,js, Mt) (25)

[0157] (26)

[0158] As an example:

[0159] Aar = -2.14 * Qnet,js - 1.08 * Mt + 77.1, correlation coefficient R 2 ≈0.94.

[0160] More specifically, the determination of parameters such as K, B, m1, P1, n, etc.:

[0161] Obtain all known parameters in formula (1) or the simplified formula (8) according to the above method, obtain a sufficient number of data sets at 1s intervals, generally more than 100,000 sets, and after processing according to the following parameter synchronous analysis and processing method, obtain a sufficient number of sets of non-linear equations, and then solve the non-linear equations to obtain parameters such as K, B, m1, P1, n, etc. The solutions of these parameters are not unique and are related to factors such as data sources and calculation accuracy requirements.

[0162] Furthermore, it also includes:

[0163] Determine NO x Measure the delay time difference between the concentration and the boiler operating parameters, and linearly fit the boiler operating parameters with the NO x measurement concentrations at different delay times to obtain the correlation coefficients at different delay times.

[0164] According to the maximum value of the correlation coefficient, determine the optimal delay time, and shift the NO x measurement concentration according to the optimal delay time to align its time with the boiler operating parameters.

[0165] It should be noted that there is a delay time difference z0 between the boiler operating parameters and the NOx concentration u measured at the inlet of the denitration system. This time difference is composed of t1, t2, and t3, and its time series is as NOx,CL shown. Figure 3 shown.

[0166] Among them, the time difference t1 between the operating parameters and the generation of NO at the furnace outlet is mainly the data transmission time of the operating parameter measurement and the generation time of NO in the furnace. This time is very short, generally less than 5s; x The time difference t2 from the generation of NO at the furnace outlet to the ammonia injection point at the denitration inlet is the flue gas flow time in the tail flue, which can be estimated by the flue gas volume and the tail flue size. Generally, it is 5 - 15s and is related to the load; x This time is very short, generally less than 5s;

[0167] The time difference t2 from the generation of NO at the furnace outlet to the ammonia injection point at the denitration inlet is the flue gas flow time in the tail flue, which can be estimated by the flue gas volume and the tail flue size. Generally, it is 5 - 15s and is related to the load; x The time difference t3 between the ammonia injection point at the denitration inlet and the NO

[0168] concentration measurement value u of the analyzer is the sum of the time for the analyzer to extract flue gas and the measurement time. According to the different lengths of the analyzer and the pipeline layout, t3 can reach 60 - 240s. x concentration measurement value u of the analyzer is the sum of the time for the analyzer to extract flue gas and the measurement time. According to the different lengths of the analyzer and the pipeline layout, t3 can reach 60 - 240s. NOx,CL The time difference t3 between the ammonia injection point at the denitration inlet and the NO

[0169] The value of t3 can be obtained through experimental methods: when the unit is in cold state, introduce NO x standard gas at the inlet of the flue gas sampling point and start timing. When the flue gas analyzer reaches 90% of the standard gas indication value, end the timing. This time difference is t3.

[0170] After the parameter synchronization analysis, the corresponding relationship between the boiler operation parameters and u NOx is as follows Figure 4 As shown, the delay time difference z0 can also be obtained through data analysis methods, that is, by linearly modeling the boiler operation parameters with u at different delay times NOx,CL to obtain the correlation coefficient R at different delay times 2 , and taking the delay time with the maximum R 2 as z0. As shown Figure 5 the delay time z0 is taken as 173 s

[0171] It can be understood that for the denitration system of large power station boilers, usually a set of ammonia injection denitration system is set on each of the A and B sides, and it is necessary to separately predict the NO x generation concentration on the A and B sides. The theoretical prediction method is the same as above, except that all boiler operation parameters are taken as the data of one side, which will not be elaborated here

[0172] For different boiler types, such as tangentially fired boilers with four corners, tangentially fired boilers with eight corners, boilers co-firing multiple fuels, etc., the prediction formulas and methods are the same

[0173] The difference between different boiler types lies in the specific division of the sub-combustion areas, and the division principle is the same, that is, it is divided according to the burner layout

[0174] The difference in co-firing multiple fuels lies in the determination method of the coal combustion parameters in the sub-combustion areas, and the determination principle is the same, that is, both are obtained through actual measurement or parameter modeling calculation, which will not be elaborated here

[0175] The above is a detailed description of an embodiment of the calculation method for the NO x generation concentration of a coal-fired boiler provided by this application. The following is an application example description of the calculation method for the NO x generation concentration of a coal-fired boiler provided by this application

[0176] According to the method provided by this application, the NO x generation concentration prediction formula of a certain coal-fired boiler (opposed firing of front and rear walls, two layers of overfire air) was solved. Since there is no direct measurement data of the coal feed rate and air volume of each nozzle, the sub-combustion area is divided into 16 (8 on each of the front and rear walls). Under a certain data source, the prediction formula for the A side is

[0177] The correlation coefficient R of this prediction formula 2 ≈0.92

[0178]

[0179] The comparison between the prediction result of this prediction formula and the actual measurement result is as Figure 6as shown

[0180] The above is a detailed description of an embodiment of the method for calculating the NO generation concentration of a coal-fired boiler provided by this application. The following is a detailed description of an embodiment of the device for calculating the NO generation concentration of a coal-fired boiler provided by this application. x The above is a detailed description of an embodiment of the method for calculating the NO generation concentration of a coal-fired boiler provided by this application. The following is a detailed description of an embodiment of the device for calculating the NO generation concentration of a coal-fired boiler provided by this application. x Detailed description of the embodiment of the device for calculating the NO generation concentration.

[0181] Please refer to Figure 7 An embodiment of this application provides a device for calculating the NO generation concentration of a coal-fired boiler, including: x A device for calculating the NO generation concentration, including:

[0182] A region division unit 201, configured to divide the combustion region of the coal-fired boiler into multiple sub-combustion regions according to the structural information of the coal-fired boiler;

[0183] A combustion parameter acquisition unit 202, configured to acquire the regional combustion parameters of each sub-combustion region;

[0184] A concentration prediction unit 203, configured to determine the predicted concentration of NO generated by the coal-fired boiler according to the regional combustion parameters and in combination with a preset NO concentration calculation formula; x A concentration prediction unit 203, configured to determine the predicted concentration of NO generated by the coal-fired boiler according to the regional combustion parameters and in combination with a preset NO concentration calculation formula; x Predicted concentration.

[0185] As Figure 8 shown, a terminal for calculating the NO generation concentration of a coal-fired boiler provided in an embodiment of this application. The implementation types of the terminal include but are not limited to: personal computers, servers, and embedded intelligent devices. The main components of the terminal include: a memory 33 and a processor 31, and the memory 33 and the processor 31 can be connected through a communication bus 34; x shown, a terminal for calculating the NO generation concentration of a coal-fired boiler provided in an embodiment of this application. The implementation types of the terminal include but are not limited to: personal computers, servers, and embedded intelligent devices. The main components of the terminal include: a memory 33 and a processor 31, and the memory 33 and the processor 31 can be connected through a communication bus 34;

[0186] The memory 33 is used to store program code, and the program code is used to implement a method for calculating the NO generation concentration of a coal-fired boiler as provided in the first aspect of this application; x The memory 33 is used to store program code, and the program code is used to implement a method for calculating the NO generation concentration of a coal-fired boiler as provided in the first aspect of this application;

[0187] The processor 31 is configured to read and execute the program code.

[0188] An embodiment of this application provides a computer-readable storage medium, in which program code is stored. The program code is used to be read and executed by a processor to implement a method for calculating the NO generation concentration of a coal-fired boiler as provided in the foregoing embodiment. x The program code is used to be read and executed by a processor to implement a method for calculating the NO generation concentration of a coal-fired boiler as provided in the foregoing embodiment.

[0189] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described terminal, device, and unit can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated here.

[0190] In several embodiments provided in the present application, it should be understood that the disclosed terminals, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in an electrical, mechanical, or other form.

[0191] Terms such as "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein, for example, can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that comprises a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0192] It should be understood that in the present application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects and indicates that three relationships can exist. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (one) of the following" or its similar expression refers to any combination of these items, including any combination of single item (one) or plural items (ones). For example, at least one (one) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0193] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0194] In addition, in each embodiment of the present invention, each functional unit can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0195] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0196] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present application.

Claims

1. A method for calculating the NO generation concentration in a coal-fired boiler, characterized in that, x Including: ​ Dividing the combustion area of the coal-fired boiler into multiple sub-combustion areas according to the structural information of the coal-fired boiler; Obtaining the regional combustion parameters of each sub-combustion area, where the regional combustion parameters include: coal combustion parameters and excess air coefficient, and the coal combustion parameters include: coal consumption, calorific value of coal, and comprehensive coal quality parameters; According to the regional combustion parameters and in combination with a preset NO x concentration calculation formula, determine the predicted NO x concentration generated by the coal-fired boiler.

2. A method for calculating the generation concentration of NO in a coal-fired boiler according to claim 1 x , characterized in that The NO x concentration calculation formula is specifically as follows: Wherein, m is the number of sub-combustion zones, K and B are coefficients, n is an exponent, G is the coal consumption of each sub-combustion zone, Qnet is the calorific value of the coal for each sub-combustion zone, MZ is the comprehensive coal quality parameter of each sub-combustion zone, α is the excess air coefficient of each sub-combustion zone, P is the unit power, Pe is the rated power of the unit, Qy is the flue gas volume at standard conditions before the boiler denitration system, μ NOx is the NO generated by boiler combustion x predicted concentration, and i is the number of the sub-combustion zone.

3. A method for calculating the NO generation concentration of a coal-fired boiler according to claim 1 x , characterized in that The obtaining method of the coal combustion parameters includes: Measuring the coal consumption of each sub-combustion area through a preset on-line coal quantity monitoring module, or calculating the average of the total coal consumption of each layer according to the burner layer layout information of the coal-fired boiler to obtain the coal consumption of each sub-combustion area; Measuring the calorific value of coal in each sub-combustion area through a preset on-line coal quality monitoring module, or calculating the calorific value of coal in each sub-combustion area through the heat balance calculation method; Measuring the nitrogen content and volatile matter of each burner layer through a preset on-line coal quality monitoring module to determine the comprehensive coal quality parameters of each sub-combustion area according to the nitrogen content and the volatile matter, or calculating the moisture parameter of each burner layer through the heat balance calculation method, and then determining the volatile matter through a preset volatile matter conversion relationship formula to determine the comprehensive coal quality parameters of each sub-combustion area according to the volatile matter.

4. A method for calculating the generation concentration of NO in a coal-fired boiler according to claim 1 x , characterized in that The obtaining method of the excess air coefficient includes: Constructing an excess air correction coefficient calculation formula according to the total primary air volume, total secondary air volume of the coal-fired boiler and the on-line measured oxygen content at the denitration inlet; Calculating the excess air coefficient of each sub-combustion area respectively according to the calculated excess air correction coefficient, combining the air volume flow relationship and coal combustion heat of each sub-combustion area.

5. A method for calculating the generation concentration of NO in a coal-fired boiler according to claim 1 x , characterized in that The dividing the combustion area of the coal-fired boiler into multiple sub-combustion areas according to the structural information of the coal-fired boiler includes: Dividing the combustion area of the coal-fired boiler into multiple sub-combustion areas along the combustion process direction with a single combustion nozzle as the smallest division unit according to the structural information of the coal-fired boiler.

6. A method for calculating the generation concentration of NO in a coal-fired boiler according to any one of claims 1 to 5 x , characterized in that Also including: Determine NO x Measure the delay time difference of the concentration relative to the boiler operation parameters, and linearly fit the boiler operation parameters with the NO at different delay times x Measure the concentration and perform a linear fit to obtain the correlation coefficients at different delay times; Determine the optimal delay time according to the maximum value of the correlation coefficient, so as to shift the NO x measurement concentration according to the optimal delay time, so that the NO x measurement concentration and the boiler operation parameters are time-aligned.

7. A method for calculating the NO generation concentration of a coal-fired boiler according to claim 2 x , characterized in that The calculation formula of the standard state flue gas volume is: In the formula, Q1 and Q2 are the total primary air volume and total secondary air volume of the boiler respectively, Aar is the ash content of the coal entering the boiler, and Gj is the coal consumption of the jth layer burner or coal mill.

8. A method for calculating the generation concentration of NO in a coal-fired boiler according to claim 2 x , characterized in that Also including: Collect multiple groups of boiler operation data, establish multiple groups of non-linear equations, and then use the least squares method to solve the non-linear equations to determine the values of each constant coefficient and exponent in the NO x concentration calculation formula according to the solution results.

9. A NO generation concentration calculation device for a coal-fired boiler, characterized in that x Including: A regional division unit for dividing the combustion area of the coal-fired boiler into multiple sub-combustion areas according to the structural information of the coal-fired boiler; A combustion parameter acquisition unit for acquiring the regional combustion parameters of each sub-combustion area; A concentration prediction unit, which is used to determine the predicted concentration of NO generated by the coal-fired boiler according to the regional combustion parameters and in combination with a preset NO concentration calculation formula. x x ​ 10. A coal-fired boiler NO x generation concentration calculation terminal, characterized in that, Including: A memory and a processor; The memory is used to store program code for implementing a method for calculating the generation concentration of NO in a coal-fired boiler as described in any one of claims 1 to 8 x ; The processor is used to read and execute the program code.

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