Method and system for controlling ammonia consumption in an sncr system

Abstract

The application discloses a kind of control method and control system of ammonia water dosage in SNCR system, belong to cement industry flue gas denitration technical field, comprising: S1, obtain the following basic data ammonia water mass concentration, surplus coefficient, raw material feeding quantity, C1 target nitrogen oxide concentration, cement raw meal clinker conversion ratio γ, constant α, constant β, the nitrogen oxide concentration generated by cement kiln decomposing furnace and ammonia utilization efficiency;S2, establish relationship model;Ammonia water control dosage*ammonia utilization efficiency*ammonia water mass concentration / 17=surplus coefficient*(cement kiln nitrogen oxide concentration*β+α*cement kiln decomposing furnace generated nitrogen oxide concentration-α*C1 target nitrogen oxide concentration) / 22.4*raw material feeding quantity (t / h) / γ / 1000;S3, utilize flue gas analyzer to test the real-time nitrogen oxide concentration in kiln tail smoke chamber in kiln, and combine basic data, and the real-time ammonia water control dosage is obtained by the above relationship model calculation.

Description

Technical Field

[0001] This invention belongs to the field of flue gas denitrification technology in the cement industry, specifically relating to a method and control system for controlling the amount of ammonia water used in an SNCR system. Background Technology

[0002] Nitrogen oxides (NOx) are harmful pollutants that can easily cause acid rain and other damage. Currently, the cement industry widely uses selective non-catalytic reduction (SNCR) technology to reduce NOx emissions. SNCR technology has been widely adopted due to its advantages such as simple retrofitting and low investment. However, a serious problem with SNCR systems in the cement industry is the inability to accurately control the amount of ammonia used in advance.

[0003] Currently, all common PID control methods for ammonia water usage in cement kilns are based on lag regulation. For example, CN114067933A uses intelligent calculation to provide information on ammonia water usage changes, but its control is based on the rate of change in nitrogen oxide emission concentration. This control is based on the nitrogen oxide concentration at the preheater outlet or chimney, where there is a significant lag in detection, without analyzing the source of the nitrogen oxides. Furthermore, comparisons between different SNCR systems are difficult to make definitively accurate due to fluctuations in background nitrogen oxide concentrations.

[0004] The current methods for controlling ammonia water in SNCR systems in the cement industry generally suffer from the following problems:

[0005] First, the amount of ammonia used is controlled by measuring the nitrogen oxide concentration in the preheater or chimney, which has a significant lag time, instead of using a pre-control method.

[0006] Second, the emission mechanism of nitrogen oxides from cement kilns was not studied; the ammonia usage was simply controlled by PID based on the change in emission concentration.

[0007] If different SNCR systems are used on the same production line, it is difficult to control the amount of ammonia used between them. This is because although it is a production line, the initial concentration of nitrogen oxide emissions changes constantly, so it is impossible to compare the advantages and disadvantages of different SNCR systems. Summary of the Invention

[0008] To address the technical problems existing in the prior art, this invention provides a method and control system for controlling the amount of ammonia in an SNCR system. This system can pre-control the initial emission concentration of nitrogen oxides in real time (the concentration of nitrogen oxides in the cement kiln and the concentration of nitrogen oxides generated in the cement kiln decomposition furnace), thereby predicting the amount of ammonia used.

[0009] The first objective of this invention is to provide a method for controlling the ammonia dosage in an SNCR system, which utilizes the real-time initial nitrogen oxide emission concentration to control the ammonia dosage in the SNCR denitrification system, comprising:

[0010] S1. Obtain basic data; the basic data includes ammonia water mass concentration, surplus coefficient, raw material input amount, C1 target nitrogen oxide concentration, cement raw material-to-clinker conversion ratio γ, constant α, constant β, nitrogen oxide concentration generated by cement kiln decomposition furnace, and ammonia utilization efficiency.

[0011] S2. Establish a relational model;

[0012] Ammonia water dosage control Ammonia utilization efficiency Ammonia concentration / 17 = surplus coefficient (Nitrogen oxide concentration in cement kiln) β+α Nitrogen oxide concentration -α generated in cement kiln decomposition furnace (Target nitrogen oxide concentration C1) / 22.4 Raw material feed rate (t / h) / γ / 1000;

[0013] S3. Use a flue gas analyzer to test the real-time nitrogen oxide concentration in the cement kiln tail flue chamber, and combine the basic data to calculate the real-time ammonia water control dosage through the above relationship model.

[0014] The concentration of nitrogen oxides generated in the cement kiln decomposition furnace is obtained as follows:

[0015] With the SNCR system not in operation, the real-time NOx concentration (NO-riser) in the kiln tail flue gas chamber was measured by a flue gas analyzer; the real-time oxygen concentration (O2-c1) and NO concentration (NO-c1) in the flue gas were measured by a flue gas analyzer at the outlet of the first-stage cyclone.

[0016] Real-time nitrogen oxide concentration generated by cement kiln decomposition furnace = (α) NO-c1-β NO-riser) / α;

[0017] Under stable cement kiln production conditions, the concentration of nitrogen oxides generated in the cement kiln decomposition furnace in the relational model is obtained by averaging the continuously collected data.

[0018] The ammonia utilization efficiency is obtained as follows: when the cement production line output is stable and the SNCR system is not in operation, the real-time NO concentration NO-c11 of the flue gas is measured by the flue gas analyzer at the outlet of the first-stage cyclone. When the SNCR system is in operation and the converted concentration of nitrogen oxides in the chimney is controlled within the target value, the real-time NO concentration NO-c12 of the flue gas is measured by the flue gas analyzer at the outlet of the first-stage cyclone.

[0019] Real-time ammonia utilization efficiency = (NO - Cl11 - NO - Cl2) α Raw material feed rate / γ / 22.4 / (ammonia water usage (L / h)) Ammonia water density (kg / L) ammonia concentration 1000 / 17);

[0020] The utilization efficiency of ammonia can be calculated by taking the average value after continuous data collection, assuming stable cement kiln production.

[0021] The second objective of this invention is to provide a control system for the ammonia dosage in an SNCR system, which uses the real-time initial nitrogen oxide emission concentration to control the ammonia dosage in the SNCR denitrification system, including:

[0022] The module acquires basic data; the basic data includes ammonia water mass concentration, surplus coefficient, raw material input amount, target nitrogen oxide concentration of C1, cement raw material-to-clinker conversion ratio γ, constant α, constant β, nitrogen oxide concentration generated by cement kiln decomposition furnace, and ammonia utilization efficiency.

[0023] Ammonia water dosage control Ammonia utilization efficiency Ammonia concentration / 17 = surplus coefficient (Nitrogen oxide concentration in cement kiln) β+α Nitrogen oxide concentration -α generated in cement kiln decomposition furnace (Target nitrogen oxide concentration C1) / 22.4 Raw material feed rate (t / h) / γ / 1000;

[0024] Control module: The real-time nitrogen oxide concentration in the cement kiln is measured using a flue gas analyzer in the kiln tail flue chamber. Combined with the basic data, the real-time ammonia water control dosage is calculated through the above-mentioned relationship model.

[0025] The concentration of nitrogen oxides generated in the cement kiln decomposition furnace is obtained as follows:

[0026] With the SNCR system not in operation, the real-time NOx concentration (NO-riser) in the kiln tail flue gas chamber was measured by a flue gas analyzer; the real-time oxygen concentration (O2-c1) and NO concentration (NO-c1) in the flue gas were measured by a flue gas analyzer at the outlet of the first-stage cyclone.

[0027] Real-time nitrogen oxide concentration generated by cement kiln decomposition furnace = (α) NO-c1-β NO-riser) / α;

[0028] Under stable cement kiln production conditions, the concentration of nitrogen oxides generated in the cement kiln decomposition furnace in the relational model is obtained by averaging the continuously collected data.

[0029] The ammonia utilization efficiency is obtained as follows: when the cement production line output is stable and the SNCR system is not in operation, the real-time NO concentration NO-c11 of the flue gas is measured by the flue gas analyzer at the outlet of the first-stage cyclone. When the SNCR system is in operation and the converted concentration of nitrogen oxides in the chimney is controlled within the target value, the real-time NO concentration NO-c12 of the flue gas is measured by the flue gas analyzer at the outlet of the first-stage cyclone.

[0030] Real-time ammonia utilization efficiency = (NO - Cl11 - NO - Cl2) α Raw material feed rate / γ / 22.4 / (ammonia water usage (L / h)) Ammonia water density (kg / L) ammonia concentration 1000 / 17);

[0031] The utilization efficiency of ammonia can be calculated by taking the average value after continuous data collection, assuming stable cement kiln production.

[0032] A third objective of this invention is to provide an information data processing terminal for implementing the aforementioned method for controlling the amount of ammonia used in the SNCR system.

[0033] A fourth objective of this invention is to provide a computer-readable storage medium including instructions that, when executed on a computer, cause the computer to perform the above-described method for controlling the amount of ammonia in an SNCR system.

[0034] The advantages and positive effects of this invention are:

[0035] First, this invention decomposes nitrogen oxides in cement kilns according to their source mechanism, with one part being fuel nitrogen oxides and the other part being thermal nitrogen oxides. Based on this, the initial emission concentration of nitrogen oxides is pre-controlled, thereby predicting the amount of ammonia water used. This is a pre-control method with no lag time.

[0036] Second, this invention utilizes the fact that the amount of nitrogen oxides produced by fuel in cement kilns is relatively constant, while the amount of thermal nitrogen oxides fluctuates more drastically with the kiln conditions. By combining the real-time measured thermal nitrogen oxides with the pre-measured fuel nitrogen oxides, the initial concentration of nitrogen oxides can be used as the basis for controlling the ammonia water consumption of the SNCR system after multiple actual measurements, thereby reducing the consumption of ammonia water and reducing operating costs.

[0037] Third, this invention proposes a method for testing the concentration of nitrogen oxides generated in the decomposition furnace (which is the amount generated when combined with the flue gas volume). This method can be used not only for controlling the ammonia water volume in the SNCR system, but also to assist in controlling the pulverized coal combustion state in the decomposition furnace.

[0038] Fourth, this invention can be used not only for controlling the ammonia content in SNCR systems, but also for evaluating the performance of SNCR systems in individual cement production lines. On a single production line, SNCR systems with high ammonia utilization efficiency perform better than those with low ammonia utilization efficiency. Ammonia utilization efficiency can also be compared by examining the impact of the SNCR system's injection point, nozzle, and injection process parameters on the denitrification effect. Detailed Implementation

[0039] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed explanations follow:

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the technical solutions of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] A method for controlling the ammonia dosage in an SNCR system, which utilizes the nitrogen oxide concentration in the cement kiln to control the ammonia dosage in the SNCR denitrification system, includes:

[0042] S1. Obtain basic data; the basic data includes ammonia water mass concentration, surplus coefficient, raw material input amount, C1 target nitrogen oxide concentration, cement raw material-to-clinker conversion ratio γ, constant α, constant β, nitrogen oxide concentration generated by cement kiln decomposition furnace, and ammonia utilization efficiency.

[0043] S2. Establish a relational model;

[0044] Ammonia water dosage control Ammonia utilization efficiency Ammonia concentration / 17 = surplus coefficient (Nitrogen oxide concentration in cement kiln) β+α Nitrogen oxide concentration -α generated in cement kiln decomposition furnace (Target nitrogen oxide concentration C1) / 22.4 Raw material feed rate (t / h) / γ / 1000;

[0045] Wherein: NOx concentration in the cement kiln is the NOx concentration in the kiln tail flue, in ppm. Ammonia water control dosage is the target control parameter, in kg / h. α is the standard airflow of the primary cyclone separator corresponding to a unit cement clinker output, in m³ / kg.cl, generally defaulted to 1.4 or measured through thermal calibration. β is the standard airflow of the secondary air corresponding to a unit cement clinker output, in m³ / kg.cl, generally defaulted to 0.4 or measured through thermal calibration. Raw meal feed rate is the real-time raw meal feed rate of the cement plant, in t / h. γ is the raw-to-clinker conversion ratio of the cement plant, dimensionless, generally defaulted to 1.6 or measured.

[0046] S3. Use a flue gas analyzer to test the real-time nitrogen oxide concentration in the cement kiln tail flue chamber, and combine the basic data to calculate the real-time ammonia water control dosage through the above relationship model.

[0047] To ensure compliance with emission standards, the amount of ammonia used must be increased by a certain margin.

[0048] The target nitrogen oxide concentration (ppm) for C1 is calculated based on emission standards and the oxygen concentration at the outlet of the primary cyclone separator.

[0049] C1 target nitrogen oxide concentration (ppm) = emission standard nitrogen oxide concentration (mg / m3) (21 - Oxygen concentration at the outlet of the first-stage cyclone separator) / 11 / 2.05;

[0050] When a cement plant is in stable production, the amount of nitrogen oxides generated in the cement kiln's decomposition furnace is approximately constant. Therefore, it can be determined through manual testing, as follows:

[0051] With the cement kiln SNCR system not in operation, the NOx concentration (NO-riser, unit: ppm) in the kiln tail flue gas chamber was tested using a flue gas analyzer; the O2 oxygen concentration (O2-c1, unit: %) and NO concentration (NO-c1, unit: ppm) in the flue gas were tested using a flue gas analyzer at the outlet of the first-stage cyclone separator.

[0052] Real-time nitrogen oxide concentration generated by cement kiln decomposition furnace = (α) NO-c1-β NO-riser) / α;

[0053] Under stable cement kiln production conditions, the concentration of nitrogen oxides generated in the cement kiln decomposition furnace in the relational model is obtained by averaging the continuously collected data.

[0054] The utilization efficiency of ammonia was determined through experimental testing. The method is as follows:

[0055] When the output of the cement production line is stable, the real-time NO concentration (NO-C11) of the flue gas is measured by the flue gas analyzer at the outlet of the first-stage cyclone separator when the SNCR system is not in operation. When the SNCR system is in operation and the converted concentration of nitrogen oxides in the chimney is controlled within the target value, the real-time NO concentration (NO-C12) of the flue gas is measured by the flue gas analyzer at the outlet of the first-stage cyclone separator.

[0056] Real-time ammonia utilization efficiency = (NO - Cl11 - NO - Cl2) α Raw material feed rate / γ / 22.4 / (ammonia water usage (L / h)) Ammonia water density (kg / L) ammonia concentration 1000 / 17);

[0057] The ammonia utilization efficiency can be calculated by taking the average value after continuous data collection under stable cement kiln production conditions. For the same production line, the ammonia utilization efficiency is constant without changing the process conditions of the SNCR system; a good SNCR system should have an ammonia utilization efficiency between 75% and 90%.

[0058] Changes in the process conditions of an SNCR system can significantly affect denitrification efficiency and ammonia consumption. Therefore, changes in the location of the spray point, nozzle type, spray pressure, and number of spray guns will inevitably alter the ammonia utilization efficiency. A good SNCR system aims to meet emission standards while minimizing ammonia consumption. Consequently, a good SNCR system will have high ammonia utilization efficiency.

[0059] The second objective of this invention is to provide a control system for the ammonia dosage in an SNCR system, which uses the nitrogen oxide concentration in the cement kiln to control the ammonia dosage in the SNCR denitrification system, including:

[0060] The module acquires basic data; the basic data includes ammonia water mass concentration, surplus coefficient, raw material input amount, target nitrogen oxide concentration of C1, cement raw material-to-clinker conversion ratio γ, constant α, constant β, nitrogen oxide concentration generated by cement kiln decomposition furnace, and ammonia utilization efficiency.

[0061] Relational model module;

[0062] Ammonia water dosage control Ammonia utilization efficiency Ammonia concentration / 17 = surplus coefficient (Nitrogen oxide concentration in cement kiln) β+α Nitrogen oxide concentration -α generated in cement kiln decomposition furnace (Target nitrogen oxide concentration C1) / 22.4 Raw material feed rate (t / h) / γ / 1000;

[0063] Wherein: NOx concentration in the cement kiln is the NOx concentration in the kiln tail flue, in ppm. Ammonia water control dosage is the target control parameter, in kg / h. α is the standard airflow of the primary cyclone separator corresponding to a unit cement clinker output, in m³ / kg.cl, generally defaulted to 1.4 or measured through thermal calibration. β is the standard airflow of the secondary air corresponding to a unit cement clinker output, in m³ / kg.cl, generally defaulted to 0.4 or measured through thermal calibration. Raw meal feed rate is the real-time raw meal feed rate of the cement plant, in t / h. γ is the raw-to-clinker conversion ratio of the cement plant, dimensionless, generally defaulted to 1.6 or measured.

[0064] Control module: The real-time nitrogen oxide concentration in the cement kiln is measured using a flue gas analyzer in the kiln tail flue chamber. Combined with the basic data, the real-time ammonia water control dosage is calculated through the above-mentioned relationship model.

[0065] To ensure compliance with emission standards, the amount of ammonia used must be increased by a certain margin.

[0066] The target nitrogen oxide concentration (ppm) for C1 is calculated based on emission standards and the oxygen concentration at the outlet of the primary cyclone separator.

[0067] C1 target nitrogen oxide concentration (ppm) = emission standard nitrogen oxide concentration (mg / m3) (21 - Oxygen concentration at the outlet of the first-stage cyclone separator) / 11 / 2.05;

[0068] When a cement plant is in stable production, the amount of nitrogen oxides generated in the cement kiln's decomposition furnace is approximately constant. Therefore, it can be determined through manual testing, as follows:

[0069] With the cement kiln SNCR system not in operation, the NOx concentration (NO-riser, unit: ppm) in the kiln tail flue gas chamber was tested using a flue gas analyzer; the O2 oxygen concentration (O2-c1, unit: %) and NO concentration (NO-c1, unit: ppm) in the flue gas were tested using a flue gas analyzer at the outlet of the first-stage cyclone separator.

[0070] Real-time nitrogen oxide concentration generated by cement kiln decomposition furnace = (α) NO-c1-β NO-riser) / α;

[0071] Under stable cement kiln production conditions, the concentration of nitrogen oxides generated in the cement kiln decomposition furnace in the relational model is obtained by averaging the continuously collected data.

[0072] The utilization efficiency of ammonia was determined through experimental testing. The method is as follows:

[0073] When the output of the cement production line is stable, the real-time NO concentration (NO-C11) of the flue gas is measured by the flue gas analyzer at the outlet of the first-stage cyclone separator when the SNCR system is not in operation. When the SNCR system is in operation and the converted concentration of nitrogen oxides in the chimney is controlled within the target value, the real-time NO concentration (NO-C12) of the flue gas is measured by the flue gas analyzer at the outlet of the first-stage cyclone separator.

[0074] Real-time ammonia utilization efficiency = (NO - Cl11 - NO - Cl2) α Raw material feed rate / γ / 22.4 / (ammonia water usage (L / h)) Ammonia water density (kg / L) ammonia concentration 1000 / 17);

[0075] The ammonia utilization efficiency can be calculated by taking the average value after continuous data collection under stable cement kiln production conditions. For the same production line, the ammonia utilization efficiency is constant without changing the process conditions of the SNCR system; a good SNCR system should have an ammonia utilization efficiency between 75% and 90%.

[0076] Changes in the process conditions of an SNCR system can significantly affect denitrification efficiency and ammonia consumption. Therefore, changes in the location of the spray point, nozzle type, spray pressure, and number of spray guns will inevitably alter the ammonia utilization efficiency. A good SNCR system is judged by two criteria: first, it meets emission standards; second, it minimizes ammonia consumption while still meeting emission standards. Therefore, a good SNCR system will necessarily have high ammonia utilization efficiency.

[0077] Specific Implementation Case 1:

[0078] Under continuous operation of a cement kiln on a cement clinker production line in Zhejiang Province with a daily output of 6,000 tons,

[0079] Methods for controlling the ammonia usage in an SNCR system. The specific steps are as follows:

[0080] Ammonia water usage control (kg / h) Ammonia utilization efficiency Ammonia concentration / 17 = surplus coefficient (Nitrogen oxide concentration in cement kiln (ppm)) β+α Nitrogen oxide concentration (ppm) generated in cement kiln decomposition furnace - α C1 target nitrogen oxide concentration (ppm) / 22.4 Raw material feed rate (t / h) / γ / 1000;

[0081] The nitrogen oxide concentration in the cement kiln is the NOx concentration in the kiln tail flue, in ppm. Ammonia water control dosage is a control parameter, in kg / h. α is the standard airflow of the primary cyclone separator corresponding to a unit cement clinker output, in m³ / kg.cl, default is 1.4. β is the standard airflow of the secondary air corresponding to a unit cement clinker output, in m³ / kg.cl, default is 0.4. Raw meal feed rate is the real-time raw meal feed rate of the cement plant, in t / h. γ is the raw-to-clinker conversion ratio of the cement plant, dimensionless, default is 1.6.

[0082] The concentration of nitrogen oxides generated in the decomposition furnace of a cement kiln was measured continuously for 24 hours and more than 6 times under stable cement kiln production conditions, as shown in the table below.

[0083] Table 1 shows the concentration measurement of nitrogen oxides generated in the decomposition furnace of a cement kiln.

[0084]

[0085] The concentration of nitrogen oxides generated in the precalciner of a cement kiln is based on: Nitrogen oxide concentration generated in the precalciner of a cement kiln = (α) NO-c1-β The NO-riser / α ratio was calculated to have an average value of 302 ppm.

[0086] The emission standard's nitrogen oxide concentration (mg / m3) is 100. The average oxygen concentration at the outlet of the first-stage cyclone separator is 1.5% to 2.5%, taking the minimum value of 1.5%. The target nitrogen oxide concentration (ppm) for C1 is equal to the emission standard's nitrogen oxide concentration (mg / m3). (21 - oxygen concentration at the outlet of the first-stage cyclone separator) / 11 = 100 (21-1.5) / 11 / 2.05=86.5ppm;

[0087] The utilization efficiency of ammonia was determined through experimental testing. The steps are as follows:

[0088] When the cement production line output is stable, and the cement kiln SNCR system is not in operation, the NO concentration (NO-C11, unit: ppm) of the flue gas is measured using a flue gas analyzer at the outlet of the first-stage cyclone separator. With the cement kiln SNCR system in operation and the converted NO concentration at the chimney controlled within the target value, the NO concentration (NO-C12, unit: ppm) of the flue gas is measured using a flue gas analyzer at the outlet of the first-stage cyclone separator.

[0089] Ammonia utilization efficiency = (NO - Cl₁₁ - NO - Cl₂) α Raw material feed rate / γ / 22.4 / (ammonia water usage (kg / h)) ammonia concentration 1000 / 17)

[0090] γ=1.6, ammonia concentration 20%.

[0091] Table 2 shows the experimental results.

[0092]

[0093] The average ammonia utilization efficiency was calculated to be 81%. The surplus factor for this plant is considered to be 10%.

[0094] Substitute into the calculation formula:

[0095] Ammonia water usage control (kg / h) Ammonia utilization efficiency Ammonia concentration / 17 = surplus coefficient (Nitrogen oxide concentration in cement kiln (ppm)) β+α Nitrogen oxide concentration (ppm) generated in cement kiln decomposition furnace - α C1 target nitrogen oxide concentration (ppm) / 22.4 Raw material feed rate (t / h) / γ / 1000

[0096] Ammonia water usage control (kg / h) 81% 20% / 17=1.1 (Nitrogen oxide concentration in cement kiln (ppm)) 0.4 + 1.4 302-1.4 86.5) / 22.4 Raw material feed rate (t / h) / 1.6 / 1000

[0097] The calculated controlled ammonia dosage (kg / h) is 1.1. 2.928 10-3 (Nitrogen oxide concentration in cement kiln (ppm)) 0.4+301.7) Raw material input rate (t / h)

[0098] When the feed rate is 365 t / h and the real-time nitrogen oxide concentration (ppm) in the cement kiln is 922 ppm, the following is introduced:

[0099] Ammonia water usage control (kg / h) = 1.1 2.928 10 -3 (922) 0.4+301.7) 365 = 787.6 kg / h

[0100] Specific Implementation Case 2:

[0101] In a cement clinker production line in Zhejiang Province with a daily output of 6,000 tons, a new precision SNCR system and an old SNCR system were installed in continuous cement kiln operation. A comparative test was conducted between the new and old SNCR systems.

[0102] Table 3 shows the experimental results of the new precision SNCR system.

[0103]

[0104] Table 4 shows the experimental results of the old SNCR system.

[0105]

[0106] The average ammonia utilization efficiency of the new precision SNCR system is 81%, while the average ammonia utilization efficiency of the old SNCR system is 65%. This shows that the ammonia utilization efficiency of the new precision SNCR system is significantly improved compared to the old system, with lower ammonia consumption and lower operating costs.

[0107] Specific Implementation Case 3:

[0108] A precise SNCR system was implemented in a cement kiln of a cement clinker production line in Zhejiang Province with a daily output of 6,000 tons. After preliminary work, the formula for controlling the ammonia water dosage was obtained as follows:

[0109] Ammonia water usage control (kg / h) = 1.1 2.928 10 -3 (Nitrogen oxide concentration in cement kiln (ppm)) 0.4+301.7) Raw material input rate (t / h)

[0110] The concentration of nitrogen oxides generated in the decomposition furnace of the cement kiln was measured continuously for 24 hours and more than 6 times under stable cement kiln production conditions, as shown in the table below.

[0111] Table 5 shows the nitrogen oxide concentration measurement table.

[0112]

[0113] On a certain day, when the raw material feeding rate was 365 t / h and the nitrogen oxide concentration (ppm) in the cement kiln was 865 ppm, the resulting nitrogen oxide emission rate was 761 kg / h. However, the actual nitrogen oxide emission concentration decreased to 44 mg / m3, which is 100 mg / m3 lower than the environmental protection standard, with a difference of more than 40 mg / m3.

[0114] The concentration of nitrogen oxides generated in the cement kiln decomposition furnace was measured continuously for 24 hours and 6 times, as shown in the table below.

[0115] Table 6 shows the measurement results.

[0116]

[0117] It can be seen that the concentration of nitrogen oxides generated in the decomposition furnace of the cement kiln is significantly lower than that in the stable production of cement kiln, with a difference of more than 100 ppm. The combustion of pulverized coal in the decomposition furnace is poor, and the reducing atmosphere is strong, which has an adverse effect on production.

[0118] An information data processing terminal is used to implement a method for controlling the amount of ammonia used in the above-mentioned SNCR system.

[0119] A computer-readable storage medium includes instructions that, when executed on a computer, cause the computer to perform the method for controlling the amount of ammonia in the aforementioned SNCR system.

[0120] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented, in whole or in part, as a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0121] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the amount of ammonia in an SNCR system, characterized in that, include: S1. Obtain basic data; the basic data includes ammonia water mass concentration, surplus coefficient, raw material input amount, C1 target nitrogen oxide concentration, cement raw material-to-clinker conversion ratio γ, constant α, constant β, nitrogen oxide concentration generated by cement kiln decomposition furnace, and ammonia utilization efficiency. S2. Establish a relational model; Ammonia water dosage control Ammonia utilization efficiency Ammonia concentration / 17 = surplus coefficient (Nitrogen oxide concentration in cement kiln) β+α Nitrogen oxide concentration -α generated in cement kiln decomposition furnace C1 target nitrogen oxide concentration) / (22.4) γ 1000 / raw material input rate), where the unit of raw material input rate is t / h; where: The ammonia utilization efficiency was obtained by measuring the real-time NO concentration in the flue gas at the outlet of the primary cyclone separator when the cement production line output was stable and the SNCR system was not in operation. c11 With the SNCR system in operation and the converted NO concentration in the chimney controlled within the target value, the real-time NO concentration in the flue gas measured by the flue gas analyzer at the outlet of the first-stage cyclone separator is as follows: c12 ; Real-time ammonia utilization efficiency = (NO c11 -NO c12 ) α Raw material input rate / (γ) 22.4 Ammonia dosage ammonia density ammonia concentration (1000 / 17), the unit for ammonia water usage is L / h, and the unit for ammonia water density is kg / L; The utilization efficiency of ammonia can be calculated by taking the average value after continuous data collection, under the condition that cement kiln production is stable. S3. Use a flue gas analyzer to test the real-time nitrogen oxide concentration in the cement kiln tail flue chamber, and combine the basic data to calculate the real-time ammonia water control dosage through the above relationship model.

2. The method for controlling the amount of ammonia in the SNCR system according to claim 1, characterized in that, The concentration of nitrogen oxides generated in the cement kiln decomposition furnace is obtained as follows: With the SNCR system not in operation, the real-time NOx concentration in the kiln tail flue chamber was measured using a flue gas analyzer. riser The real-time oxygen concentration (O2-Cl) and NO concentration in the flue gas were measured using a flue gas analyzer at the outlet of the primary cyclone separator. c1 ; Real-time nitrogen oxide concentration generated by cement kiln decomposition furnace = (α) NO c1 -β NO riser ) / α; Under stable cement kiln production conditions, the concentration of nitrogen oxides generated in the cement kiln decomposition furnace is obtained by averaging the continuously collected data in the relational model.

3. A control system for the ammonia dosage in an SNCR system, characterized in that, include: The module acquires basic data; the basic data includes ammonia water mass concentration, surplus coefficient, raw material input amount, target nitrogen oxide concentration of C1, cement raw material-to-clinker conversion ratio γ, constant α, constant β, nitrogen oxide concentration generated by cement kiln decomposition furnace, and ammonia utilization efficiency. The relationship model is: ammonia water usage control Ammonia utilization efficiency Ammonia concentration / 17 = surplus coefficient (Nitrogen oxide concentration in cement kiln) β+α Nitrogen oxide concentration -α generated in cement kiln decomposition furnace C1 target nitrogen oxide concentration) / (22.4) γ 1000 / raw material input rate), where the unit of raw material input rate is t / h; where: The ammonia utilization efficiency was obtained by measuring the real-time NO concentration in the flue gas at the outlet of the primary cyclone separator when the cement production line output was stable and the SNCR system was not in operation. c11 With the SNCR system in operation and the converted NO concentration in the chimney controlled within the target value, the real-time NO concentration in the flue gas measured by the flue gas analyzer at the outlet of the first-stage cyclone separator is as follows: c12 ; Real-time ammonia utilization efficiency = (NO c11 -NO c12 ) α Raw material input rate / (γ) 22.4 Ammonia dosage ammonia density ammonia concentration (1000 / 17), the unit for ammonia water usage is L / h, and the unit for ammonia water density is kg / L; The utilization efficiency of ammonia can be calculated by taking the average value after continuous data collection, under the condition that cement kiln production is stable. Control module; The real-time nitrogen oxide concentration in the cement kiln tail flue gas chamber was measured using a flue gas analyzer, and the real-time ammonia water control dosage was calculated using the above-mentioned relationship model, based on the basic data.

4. The control system for ammonia dosage in the SNCR system according to claim 3, characterized in that, The concentration of nitrogen oxides generated in the cement kiln decomposition furnace is obtained as follows: With the SNCR system not in operation, the real-time NOx concentration in the kiln tail flue chamber was measured using a flue gas analyzer. riser The real-time oxygen concentration (O2-Cl) and NO concentration in the flue gas were measured using a flue gas analyzer at the outlet of the primary cyclone separator. c1 ; Real-time nitrogen oxide concentration generated by cement kiln decomposition furnace = (α) NO c1 -β NO riser ) / α; Under stable cement kiln production conditions, the concentration of nitrogen oxides generated in the cement kiln decomposition furnace is obtained by averaging the continuously collected data in the relational model.

5. An information data processing terminal, characterized in that, A method for controlling the amount of ammonia in the SNCR system according to any one of claims 1-2.

6. A computer-readable storage medium, characterized in that, Including instructions that, when run on a computer, cause the computer to perform a method for controlling the amount of ammonia in the SNCR system according to any one of claims 1-2.

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