A method for measuring a nitrogen oxide bias ratio

Abstract

This invention discloses a method for measuring nitrogen oxide (NOx) deviation. The method involves obtaining the distribution of an ammonia injection grid, setting the distribution of sampling holes on two cross-sections in the flue based on the grid distribution, substituting the sampling hole distribution into a preset simulation state to correct it, obtaining a corrected distribution, and setting the sampling holes accordingly. NOx parameters in the flue are obtained from the two cross-sections, and the opening of the ammonia injection valve is controlled based on these parameters. This application accurately obtains NOx parameters by setting the sampling hole distribution based on the ammonia injection grid distribution, and then controls the ammonia injection valve opening based on these parameters. By controlling the ammonia injection valve opening based on the content of NOx and other emissions, the ammonia injection quantity is accurately controlled, improving economic applicability and environmental friendliness.

Description

Technical Field

[0001] This application relates to the field of boiler testing technology, and more specifically, to a method for measuring nitrogen oxide deviation. Background Technology

[0002] In the operation of denitrification systems for coal-fired boilers, in order to improve denitrification efficiency and ensure energy conservation and emission reduction, the process of removing nitrogen oxides from combustion flue gas to prevent environmental pollution has become a critical issue worldwide. The two main technologies globally are SCR and SNCR. These two technologies are largely similar except that SCR uses a catalyst, resulting in a lower reaction temperature than SNCR. However, considering construction and operating costs, SCR requires at least several times, even more than ten times, the investment of SNCR. Each has its advantages and disadvantages. The principle of denitrification is to prevent excessive NOx pollution from coal combustion in the boiler, requiring coal denitrification treatment. This is divided into pre-combustion denitrification, combustion-process denitrification, and post-combustion denitrification.

[0003] In SCR, precise NO is obtained for each ammonia injection grid area. X Value and NO of the entire cross section X The value becomes exceptionally important. NO X The value is obtained through both precise analysis by the analyzer and representativeness of the flue gas sampling. In existing technologies, the measurement of NO... X The value is usually measured using a single cross-section, which leads to the measurement of NO. X Inaccurate values ​​prevent accurate control of ammonia injection rates. Inappropriate ammonia injection rates lead to NO generation. X Too high or too low a value can lead to problems such as economic losses or environmental pollution.

[0004] Therefore, improving the accuracy of ammonia injection control is a technical problem that needs to be solved. Summary of the Invention

[0005] This invention provides a method for comparing and measuring nitrogen oxide deviations, thereby solving the technical problem of low accuracy in ammonia injection control in existing technologies. This method is applied to denitrification systems in coal-fired boilers, and includes:

[0006] Obtain the distribution of the ammonia injection grid, and set the distribution of sampling holes on the dual sections of the flue according to the distribution of the ammonia injection grid;

[0007] Substitute the distribution of sampling holes on the dual cross-section into the preset simulation state, correct the distribution of sampling holes on the dual cross-section, and obtain the corrected distribution of sampling holes on the dual cross-section. Set the sampling holes according to the corrected distribution of sampling holes on the dual cross-section.

[0008] According to the double cross section, a nitrogen oxide parameter in the flue is obtained, and the ammonia injection valve opening degree is controlled according to the nitrogen oxide parameter.

[0009] In some embodiments of the present application, the double cross section includes a first cross section and a second cross section, the sampling holes on the first cross section are first sampling holes, and the sampling holes on the second cross section are second sampling holes, and each ammonia injection grid corresponds to one first sampling hole and one second sampling hole.

[0010] In some embodiments of the present application, the distribution of the sampling holes on the double cross section is substituted into a preset simulation state, and the distribution of the sampling holes on the double cross section is corrected to obtain a corrected distribution of the sampling holes on the double cross section, and the correction is specifically as follows:

[0011] The distribution of the sampling holes on the double cross section is substituted into a preset simulation state to obtain a simulation result.

[0012] The distribution of the sampling holes on the double cross section is corrected according to the simulation result.

[0013] In some embodiments of the present application, the distribution of the sampling holes on the double cross section is corrected according to the simulation result, and the correction is specifically as follows:

[0014] If the simulation result meets the preset requirement, the distribution of the sampling holes on the double cross section is not corrected, and the distribution of the sampling holes on the double cross section is taken as the corrected distribution of the sampling holes on the double cross section.

[0015] If the simulation result does not meet the preset requirement, the distribution of the sampling holes on the double cross section is corrected to obtain a corrected distribution of the sampling holes on the double cross section.

[0016] In some embodiments of the present application, the nitrogen oxide parameter in the flue is obtained according to the double cross section, and the nitrogen oxide parameter is specifically as follows:

[0017] The nitrogen oxide parameter includes a nitrogen oxide average value and a nitrogen oxide cycle value.

[0018] The nitrogen oxide average value is obtained according to the first cross section, and the nitrogen oxide cycle value is obtained according to the second cross section.

[0019] In some embodiments of the present application, the ammonia injection valve opening degree is controlled according to the nitrogen oxide parameter, and the control is specifically as follows:

[0020] A deviation value is obtained according to the nitrogen oxide average value and the nitrogen oxide cycle value, and the ammonia injection valve opening degree is controlled according to the deviation value.

[0021] In some embodiments of the present application, the ammonia injection valve opening degree is controlled according to the deviation value, and the control is specifically as follows:

[0022] If the deviation value exceeds a first preset threshold, the ammonia injection valve opening degree is increased.

[0023] If the deviation value is between the first preset threshold and the second preset threshold, the ammonia injection valve opening degree is not changed;

[0024] If the deviation value is below the second preset threshold, the ammonia injection valve opening degree is reduced;

[0025] The first preset threshold is greater than the second preset threshold.

[0026] By applying the above technical solution, the distribution of the ammonia injection grid is obtained, and the distribution of the sampling hole on the double section in the flue is set according to the distribution of the ammonia injection grid; the distribution of the sampling hole on the double section is substituted into the preset simulation state, and the distribution of the sampling hole on the double section is corrected to obtain the corrected distribution of the sampling hole on the double section, and the sampling hole is set according to the corrected distribution of the sampling hole on the double section; the nitrogen oxide parameter in the flue is obtained according to the double section, and the ammonia injection valve opening degree is controlled according to the nitrogen oxide parameter. The distribution of the sampling hole is set according to the distribution of the ammonia injection grid, so that the nitrogen oxide parameter is accurately obtained, and the ammonia injection valve opening degree is controlled according to the nitrogen oxide parameter. The ammonia injection valve opening degree is controlled according to the content of the nitrogen oxide and other exhausts, so that the ammonia injection amount is accurately controlled, and the economic applicability and environmental protection possibility are improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 A flowchart of a nitrogen oxide deviation comparison measurement method according to an embodiment of the present application is shown;

[0029] Figure 2 A structure diagram of a device for realizing measurement according to another embodiment of the present application is shown;

[0030] Figure 3 A structure diagram of a first section in a device according to another embodiment of the present application is shown;

[0031] Figure 4 A structure diagram of a second section in a device according to another embodiment of the present application is shown.

[0032] 1, flue; 2, first section; 3, second section; 4, main pipe; 5, temperature and pressure flow; 62, second branch pipe; 63, first branch pipe; 7, sampling hole; 8, switching device. DETAILED DESCRIPTION

[0033] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0034] The embodiments of the present application provide a nitrogen oxide deviation comparison measurement method, which is applied to a coal boiler denitration system, as shown in the figure, the method comprises the following steps: Figure 1

[0035] In step S101, the distribution of the ammonia injection grid is obtained, and the distribution of the sampling holes on the double section in the flue 1 is set according to the distribution of the ammonia injection grid.

[0036] In the embodiment, the distribution of the ammonia injection grid in the coal boiler denitration system is obtained, and the distribution of the ammonia injection grid includes the basic conditions such as the position, number and size of the ammonia injection grid. The distribution of the sampling holes on the double section in the flue 1 is set according to the distribution of the ammonia injection grid, and the distribution of the sampling holes on the double section includes the basic conditions such as the position, size and number of the sampling holes. The distribution of the sampling holes on the double section obtained here is a hypothetical or preset condition, which needs to be checked or verified before implementation.

[0037] It should be noted that the measurement of the nitrogen oxide content value is generally performed by setting a single section in the flue 1 to collect data. In the present scheme, two single sections are provided to collect different nitrogen oxide parameters, and the deviation between the two is used to control the opening degree of the ammonia injection valve, so as to control the ammonia injection amount.

[0038] In order to improve the accuracy of data collection, in some embodiments of the present application, the double section includes a first section 2 and a second section 3, the sampling holes on the first section 2 are first sampling holes, and the sampling holes on the second section 3 are second sampling holes. Each ammonia injection grid corresponds to one first sampling hole and one second sampling hole.

[0039] In the embodiment, each ammonia injection grid corresponds to one first sampling hole and one second sampling hole, which means that each ammonia injection grid and the first sampling hole and the second sampling hole are at the same horizontal position.

[0040] In step S102, the distribution of the sampling holes on the double section is substituted into the preset simulation state, the distribution of the sampling holes on the double section is corrected, the corrected distribution of the sampling holes on the double section is obtained, and the sampling holes are set according to the corrected distribution of the sampling holes on the double section.

[0041] ​In this embodiment, the preset simulation state is a flow field simulation state, which is a special condition for simulation or modeling in the power plant. The distribution of the double-section sampling holes in step S101 is checked or inspected through the preset simulation state, so as to obtain the most suitable distribution of the double-section sampling holes.

[0042] In order to improve the reliability of the sampling hole distribution, in some embodiments of the present application, the distribution of the double-section sampling holes is substituted into the preset simulation state to correct the distribution of the double-section sampling holes, and the corrected distribution of the double-section sampling holes is obtained. Specifically, the distribution of the double-section sampling holes is substituted into the preset simulation state to obtain a simulation result; and the distribution of the double-section sampling holes is corrected according to the simulation result.

[0043] In order to further improve the reliability of the sampling hole distribution, in some embodiments of the present application, the distribution of the double-section sampling holes is corrected according to the simulation result. Specifically, if the simulation result meets the preset requirement, the distribution of the double-section sampling holes is not corrected, and the distribution of the double-section sampling holes is taken as the corrected distribution of the double-section sampling holes; if the simulation result does not meet the preset requirement, the distribution of the double-section sampling holes is corrected to obtain the corrected distribution of the double-section sampling holes.

[0044] In step S103, the nitrogen oxide parameter in the flue 1 is obtained according to the double sections, and the ammonia injection valve opening degree is controlled according to the nitrogen oxide parameter.

[0045] In this embodiment, the nitrogen oxide average value and the nitrogen oxide wheel value are obtained according to the double sections, and the ammonia injection valve opening degree is controlled according to the difference between the two values.

[0046] In order to improve the accuracy of the control, in some embodiments of the present application, the nitrogen oxide parameter in the flue 1 is obtained according to the double sections. Specifically, the nitrogen oxide parameter includes the nitrogen oxide average value and the nitrogen oxide wheel value. The nitrogen oxide average value is obtained according to the first section 2, and the nitrogen oxide wheel value is obtained according to the second section 3.

[0047] In some embodiments of the present application, the ammonia injection valve opening degree is controlled according to the nitrogen oxide parameter. Specifically, a deviation value is obtained according to the nitrogen oxide average value and the nitrogen oxide wheel value, and the ammonia injection valve opening degree is controlled according to the deviation value.

[0048] In some embodiments of the present application, the ammonia injection valve opening degree is controlled according to the deviation value. Specifically, if the deviation value exceeds a first preset threshold, the ammonia injection valve opening degree is increased; if the deviation value is between the first preset threshold and a second preset threshold, the ammonia injection valve opening degree is not changed; and if the deviation value is lower than the second preset threshold, the ammonia injection valve opening degree is decreased. The first preset threshold is greater than the second preset threshold.

[0049] In this embodiment, an interval value is set according to historical data or actual application of the denitration system, the interval value is maximum first preset threshold value and minimum second preset threshold value. The deviation value is the difference between the nitrogen oxide average value and the nitrogen oxide wheel value. If the deviation value exceeds the first preset threshold value, it indicates that the ammonia injection amount is small, and the ammonia injection amount needs to be increased, so the ammonia injection valve opening is increased, and the ammonia injection valve of the corresponding region (the first sampling hole and the second sampling hole) is controlled according to the region corresponding to the ammonia injection grid. If the deviation value is between the first preset threshold value and the second preset threshold value, it indicates that it is in a normal state, and the ammonia injection valve opening is not changed. If the deviation value is lower than the second preset threshold value, it indicates that the ammonia injection amount is too much, and the ammonia injection amount needs to be reduced, so the ammonia injection valve opening is reduced.

[0050] It can be understood that the deviation value can also be in other forms, such as an image, a curve or a straight line is generated according to the deviation value, and it is determined whether the curve or the straight line is within the preset range, which also belongs to the protection scope of the present application.

[0051] By applying the above technical solution, the distribution of the ammonia injection grid is obtained, the distribution of the sampling hole on the double section in the flue 1 is set according to the distribution of the ammonia injection grid; the distribution of the sampling hole on the double section is substituted into the preset simulation state, and the distribution of the sampling hole on the double section is corrected to obtain the corrected distribution of the sampling hole on the double section, and the sampling hole is set according to the corrected distribution of the sampling hole on the double section; the nitrogen oxide parameter in the flue 1 is obtained according to the double section, and the ammonia injection valve opening is controlled according to the nitrogen oxide parameter. The present application sets the distribution of the sampling hole according to the distribution of the ammonia injection grid, so as to accurately obtain the nitrogen oxide parameter, and controls the ammonia injection valve opening according to the nitrogen oxide parameter. The ammonia injection valve opening is controlled according to the content of the exhaust gas such as nitrogen oxide, so as to accurately control the ammonia injection amount, and improve the economic applicability and environmental protection possibility.

[0052] Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by hardware, or by means of software and necessary general hardware platform. Based on such understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a U disk, a mobile hard disk, etc.), and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the method described in each embodiment of the present application.

[0053] In order to further illustrate the technical idea of the present application, the technical solution of the present application will be described in combination with specific application scenarios.

[0054] The specific device structure for obtaining the nitrogen oxide parameter by the double section in the above method is as follows: Figures 2-4As shown, the flue 1 is provided with a double cross-section structure for measuring nitrogen oxide parameters, the first cross-section 2 and the second cross-section 3 are both vertically arranged in the flue 1, the first cross-section 2 includes the first branch pipe 63, the first sampling hole and the main pipe 4, and the second cross-section 3 includes the second branch pipe 62, the second sampling hole and the main pipe 4, here, the sampling holes are arranged according to the distribution obtained in step S102. A plurality of first sampling holes are arranged on each first branch pipe 63, and only one second sampling hole is arranged at the bottom end of each second branch pipe 62, here, the number of second branch pipes 62 corresponds to the number of first sampling holes, and the positional relationship is adjusted correspondingly, for example, two sampling holes are arranged on the first branch pipe 63, and two second branch pipes 62 are arranged correspondingly, so that two second sampling holes are arranged. The temperature and pressure flow is used to collect and measure the temperature of the gas.

[0055] According to the partition of the ammonia injection grid, one wheel area corresponds to the position of one ammonia injection grid on the cross-section.

[0056] When the first cross-section 2 is measured, the plurality of first sampling holes simultaneously collect the gas, and when the second cross-section 3 is measured, the single second sampling hole collects the gas. The corresponding first sampling hole and second sampling hole are measured simultaneously.

[0057] The second cross-section 3 further includes a switching device 8 for switching to single second branch pipe 62 measurement.

[0058] It should be noted that each ammonia injection grid is at the same horizontal position with a first sampling hole and a second sampling hole. The first sampling hole and the second sampling hole are the same size to ensure that the gas inlet amount of each hole is consistent. The sampling hole 7 includes the first sampling hole and the second sampling hole.

[0059] The average value of nitrogen oxide is obtained through the first cross-section 2: the valve of each first sampling hole is opened at the same time, the gas is mixed into the flue 1 outside the main pipe to form a mixed flow, and then the mixed flow is measured by the analyzer to obtain the full cross-section NOx value. X The data obtained is the average value of NOx. X The analyzer obtains the average value of NOx.

[0060] The wheel value of nitrogen oxide is obtained through the second cross-section 3: the gas is sequentially introduced into the second sampling hole according to the preset wheel area sequence, and then the gas is measured by the analyzer to obtain the NOx value of one wheel area. X The NOx value of all hole inlets is measured, and the NOx wheel value is obtained. X (When the second sampling hole of one wheel area is opened, the valves of the second sampling holes of the remaining wheel areas are closed)

[0061] According to the above content, the nitrogen oxide wheel value of each wheel area is obtained, the nitrogen oxide wheel value is subtracted from the average value of nitrogen oxide to obtain a deviation value, and the opening degree of the ammonia injection valve is controlled according to the deviation value.

[0062] It should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the foregoing examples, those skilled in the art will understand that modifications can be made to the technical solutions described in the foregoing examples, or some of the technical features thereof can be replaced by equivalent features, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for measuring nitrogen oxide deviation, characterized in that, The method, applied to a denitrification system for a coal-fired boiler, includes: Obtain the distribution of the ammonia injection grid, and set the distribution of sampling holes on the dual sections of the flue according to the distribution of the ammonia injection grid; Substitute the distribution of sampling holes on the dual cross-section into the preset simulation state, correct the distribution of sampling holes on the dual cross-section, and obtain the corrected distribution of sampling holes on the dual cross-section. Set the sampling holes according to the corrected distribution of sampling holes on the dual cross-section. The dual-section includes a first section and a second section. The first section includes a first branch pipe, a first sampling hole, and a main pipe. The second section includes a second branch pipe, a second sampling hole, and a main pipe. Each first branch pipe has multiple first sampling holes, and each second branch pipe has only one second sampling hole at its bottom end. The number of second branch pipes corresponds to the number of first sampling holes, and their positional relationships are adjusted accordingly. Each ammonia injection grid corresponds to one first sampling hole and one second sampling hole. The ammonia injection grid is divided into zones, with one ammonia injection grid corresponding to a wheel zone on the cross section. Several wheel zones are set on the first and second cross sections. The average value of nitrogen oxides is obtained based on the first cross section, including: simultaneously opening the valve of each first sampling hole, allowing air to enter at the same time, mixing and entering the outer main pipe of the flue to form a mixed flow, and then entering the analyzer to measure the nitrogen oxide value of the entire cross section. The data obtained is the average value of nitrogen oxides. The nitrogen oxide wheel value is obtained according to the second section, including: gas is introduced into the second sampling hole in sequence according to the preset wheel area order, and then the nitrogen oxide value of one wheel area is measured in the analyzer. This process is repeated until the nitrogen oxide value of all the holes is measured, which is the nitrogen oxide wheel value. When the second sampling hole of one wheel area is opened, the valves of the second sampling holes of the other wheel areas are closed. The deviation value is obtained based on the average value and the rotation value of nitrogen oxides, and the opening degree of the ammonia injection valve is controlled based on the deviation value.

2. The nitrogen oxide deviation comparison and measurement method as described in claim 1, characterized in that, The distribution of sampling holes on the dual cross-sections is substituted into a preset simulation state to correct the distribution of sampling holes on the dual cross-sections, resulting in the corrected distribution of sampling holes on the dual cross-sections, as follows: The distribution of sampling holes on the dual cross-sections is substituted into the preset simulation state to obtain the simulation results; The distribution of sampling holes on the dual cross-sections was corrected based on the simulation results.

3. The nitrogen oxide deviation comparison and measurement method as described in claim 2, characterized in that, The distribution of sampling holes on the dual cross-sections is corrected based on the simulation results, specifically as follows: If the simulation results meet the preset requirements, no correction will be made, and the distribution of sampling holes on the dual cross-section will be used as the corrected distribution of sampling holes on the dual cross-section. If the simulation results do not meet the preset requirements, corrections are made to obtain the distribution of sampling holes on the corrected dual cross-sections.

4. The nitrogen oxide deviation comparison and measurement method as described in claim 1, characterized in that, The opening degree of the ammonia injection valve is controlled according to the deviation value, specifically as follows: If the deviation exceeds the first preset threshold, the opening of the ammonia injection valve will be increased; If the deviation value is between the first preset threshold and the second preset threshold, the opening degree of the ammonia injection valve will not be changed. If the deviation value is lower than the second preset threshold, the opening degree of the ammonia injection valve will be reduced. The first preset threshold is greater than the second preset threshold.

Images