Ammonia spraying control method and device and SCR denitration device

Abstract

The invention discloses an ammonia spraying control method and device and an SCR denitration device.The ammonia spraying control method comprises the following steps that the gas content in a flue is monitored in real time, and detection data are obtained; prediction data are obtained according to the detection data, and the injection amount of the reducing agent in the flue is determined according to the prediction data; the detection data comprises the NOx concentration C0 at the flue inlet, and the prediction data comprises the NOx concentration C1 at the SCR reactor inlet. The problem that an NH3 concentration field and an NOx concentration field are not matched due to ammonia spraying delay is effectively solved, the phenomena that ammonia escape is increased and a denitration catalyst and the cold end of a downstream air pre-heater are subjected to ash deposition and blockage due to excessive spraying of a reducing agent are reduced, the problem that NOx at an outlet of an SCR reactor is too high due to insufficient spraying of a local reducing agent is solved, and the service life of the SCR reactor is prolonged. And the control is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of denitration, and in particular to an ammonia injection control method and device, and an SCR denitration device. Background Art

[0002] In modern glass enterprises, cement, steel and other industries, nitrogen oxides (NO x ) As an important pollutant in the original flue gas, it has always been a difficult and painful point for environmental protection treatment. x The treatment method is the selective catalytic reduction (SCR) denitrification technology, that is, under the action of the catalyst, the reducing agent ammonia or urea is sprayed to reduce the NO in the flue gas. x Reduced to N2 and H2O.

[0003] During the denitrification control process, due to the adjustment of boiler load or combustion mode, the flue gas flow and NO x The distribution of NH3 changes accordingly, and the ammonia injection method of the traditional SCR denitrification technology cannot make the NH3 concentration field and NO x The concentration field matching may cause local excessive ammonia injection, increase ammonia escape, and increase the probability of dust accumulation and blockage of the denitrification catalyst and the cold end of the downstream air preheater, thus affecting the normal operation of the unit; on the other hand, there may also be local insufficient ammonia injection, resulting in NO at the SCR outlet. x High, NO x The problem of poor concentration uniformity.

[0004] Although there are ammonia injection control methods such as multi-point ammonia injection and precise ammonia injection on the market, this method cannot effectively solve the NH3 concentration field and NO caused by ammonia injection delay. x Problems caused by concentration field mismatch. Summary of the invention

[0005] The main purpose of the present invention is to provide an ammonia injection control method and device, and an SCR denitrification device, which aims to improve the NH3 concentration field and NO caused by the delayed ammonia injection. x Problems caused by concentration field mismatch.

[0006] To achieve the above objectives, in a first aspect, the present invention provides an ammonia injection control method, comprising: Monitor the gas content in the flue in real time and obtain detection data; Obtaining prediction data according to the detection data, and determining the injection amount of the reducing agent in the flue according to the prediction data; The test data includes NO at the flue inlet x Concentration C0, the predicted data includes NO at the inlet of the SCR reactor x Concentration C1.

[0007] In one embodiment, “obtaining prediction data based on detection data” includes: Get the NO at the flue inlet within time t x The average concentration ; According to C0, And the predicted multiple N is used to obtain C1.

[0008] In one embodiment, “determining the injection amount of the reducing agent in the flue according to the prediction data” includes: According to C1, C2, Q and V m The injection amount of reducing agent m is obtained, where C2 is NO x Emission control target value, Q is the standard dry flue gas volume, V m is the molar ratio of ammonia to nitrogen.

[0009] In one embodiment, the standard dry flue gas volume Q is calculated by the natural gas consumption V 天然气 , Heavy oil consumption m 重油 And the amount of petroleum coke m 石油焦 get.

[0010] In one embodiment, “determining the injection amount of the reducing agent in the flue according to the prediction data” further includes: m is corrected according to the correction factor K.

[0011] In a second aspect, the present invention provides an ammonia injection control device, comprising: The smoke detector is installed at the smoke duct to monitor the gas composition and parameters in the smoke duct in real time; An ammonia spraying assembly is connected to the flue and is used to spray a reducing agent into the flue; The control system is electrically connected to the smoke detector and the ammonia spraying assembly, and is used to obtain the predicted data according to the detection data of the smoke detector, and determine the injection amount of the reducing agent according to the predicted data; the detection data includes the NO x Concentration C0, the predicted data includes NO at the inlet of the SCR reactor x Concentration C1.

[0012] In one embodiment, the ammonia injection assembly comprises: A delivery main pipe, on which a regulating valve is provided, the regulating valve is electrically connected to a control system to adjust the injection amount of the reducing agent according to the opening of the regulating valve; At least one ammonia spraying grid is communicated with the conveying main pipe, and a nozzle is arranged on the ammonia spraying grid.

[0013] In one embodiment, the smoke detector is arranged at the entrance of the smoke duct; and / or, The ammonia injection assembly is arranged at the inlet of the SCR reactor.

[0014] In one embodiment, the control system comprises: An autonomous adjustment module is used to obtain prediction data based on the detection data of the smoke detector, and to adjust the injection amount of the reducing agent based on the prediction data; The passive closing module is used to delay the closing of the ammonia injection component according to the action signal of the combustion equipment.

[0015] In a third aspect, the present invention provides an SCR denitration device, comprising an SCR reactor and the above-mentioned ammonia injection control device.

[0016] The control method of the present invention monitors NO in flue gas in real time x Concentration C0, based on which the NO flowing through the inlet of the SCR reactor is estimated x The concentration C1 is then used to determine the amount of reducing agent injected, thereby effectively solving the problem of NH3 concentration field and NO x The problem of concentration field mismatch not only reduces the increase of ammonia slip caused by excessive injection of reducing agent, the accumulation of dust and blockage of denitration catalyst and cold end of downstream air preheater, but also improves the NO at the outlet of SCR reactor caused by insufficient local injection of reducing agent. x Therefore, the present invention can improve the NH3 concentration field and NO caused by the delay of ammonia injection. X Problems caused by concentration field mismatch. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on the structures shown in these accompanying drawings without paying any creative work.

[0018] Figure 1 A schematic flow chart of an ammonia injection control method according to an embodiment of the present invention; Figure 2 It is a structural schematic diagram of an ammonia injection control device in one embodiment of the present invention; Figure 3 This is a curve diagram showing the change of denitration efficiency over time during operation of the SCR denitration device in one embodiment of the present invention.

[0019] Description of Figure Numbers 100. Ammonia spray control device; 11. Smoke detector; 12. Ammonia spray assembly; 200, flue; 300. SCR reactor. DETAILED DESCRIPTION

[0020] It should be noted that if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. "At least one" appearing in the embodiments of the present invention refers to one or more, and "more than one" refers to two or more.

[0021] In the description of the embodiments of the present invention, if technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0022] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0023] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0024] During the denitrification control process, due to the adjustment of boiler load or combustion mode, the flue gas flow and NO x The distribution of NO changes accordingly, while the traditional SCR denitrification technology ammonia injection method (ammonia injection grid) assumes that the flue gas flow and NO x The distribution is fixed, so it is impossible to make the NH3 concentration field and NO xConcentration field matching may, on the one hand, cause local excessive ammonia injection, increase ammonia escape, and increase the probability of dust accumulation and blockage of the denitrification catalyst and the cold end of the downstream air preheater, thereby affecting the normal operation of the unit; in addition, when the rear end of the combustion equipment is a bag filter, excessive ammonia escape will cause the dust filter bag to stick, the air permeability of the dust collector filter bag will deteriorate, the resistance will increase, the frequency of the environmental protection fan will increase, and the power consumption will increase (in severe cases, the operating power consumption will increase by 30%-100%); when the sulfur content in the flue gas is high, excessive ammonia escape will react with SO3 in the flue gas to form ammonium bisulfate. When the temperature drops below 185°C, the gaseous ammonium bisulfate generated in the flue gas will solidify on the heat transfer element of the cold section of the waste heat boiler, causing salt accumulation and scaling in the cold section of the waste heat boiler, and then corrosion, increasing maintenance costs. On the other hand, there may also be insufficient local ammonia injection, resulting in NO x High, NO x The problem of poor concentration uniformity.

[0025] In order to solve the above problems, the current mainstream ammonia injection control method is the multi-point ammonia injection method or the precise ammonia injection method. The multi-point ammonia injection method refers to setting multiple ammonia injection ports at different positions of the flue to spray the reducing agent evenly into the flue, so that the reducing agent and NO in the flue gas can be separated. x Fully mix to improve denitrification efficiency and reduce ammonia escape. The precise ammonia injection method refers to the method of accurately injecting the appropriate amount of reducing agent into the flue through intelligent control, ammonia injection grid optimization, flow field simulation and optimization, etc., which can reduce ammonia escape and improve denitrification efficiency.

[0026] Although the above method can reduce ammonia escape to a certain extent, the flue gas monitoring equipment has a delay of 3min-6min, that is, the flue gas NO displayed on the flue gas monitoring equipment x The concentration value is already the detection value of the position 3min-6min ago. At this time, there will still be errors in determining the amount of reducing agent injection based on the delayed data value. Therefore, the existing method cannot effectively improve the NH3 concentration field and NO caused by the delay in ammonia injection. X Problems caused by concentration field mismatch.

[0027] Based on the above considerations, in order to improve the problem caused by delayed ammonia injection, an ammonia injection control method is designed, which can detect the delayed NO x The concentration value is predicted, and then the amount of reducing agent injection is determined based on the predicted value, thereby improving the control accuracy.

[0028] According to some embodiments of the present invention, reference Figure 1The present invention provides an ammonia injection control method, comprising the following steps: real-time monitoring of the gas content in the flue and obtaining detection data; obtaining prediction data based on the detection data, and determining the injection amount of the reducing agent in the flue based on the prediction data; the detection data includes NO at the flue inlet x Concentration C0, the predicted data includes NO at the inlet of the SCR reactor x Concentration C1.

[0029] The flue refers to the channel connecting the combustion equipment (such as boiler) and the denitrification device (such as SCR reactor) and the subsequent environmental protection treatment equipment, which is used to remove nitrogen oxides NO x Flue gas is transported from the combustion area to the denitrification system for treatment. The gas content in the flue includes but is not limited to SO2, NO, NO2, NH3, etc.

[0030] NO at the inlet of SCR reactor x Concentration C1 refers to the NO concentration at the ammonia injection grid flowing through the ammonia injection assembly. x Concentration, that is, according to the NO x The concentration C0 predicts the NO at the ammonia injection grid flowing through the ammonia injection assembly. x The concentration C1 is used to determine the amount of reducing agent injected.

[0031] The reducing agent can be ammonia or urea, which can reduce NO in the flue gas. x Reduced to N2 and H2O.

[0032] The present invention determines the injection amount of the reducing agent by inferring C1, which can make the NH3 concentration field and NO x The concentration field is matched, thereby reducing the increase of ammonia slip caused by excessive injection of reducing agent, the accumulation of dust and blockage of denitration catalyst and cold end of downstream air preheater, and improving the NO at the outlet of SCR reactor caused by insufficient local injection of reducing agent. x For problems with high pressure, the control is more precise.

[0033] According to some embodiments of the present invention, "obtaining prediction data based on detection data" includes the following steps: obtaining the NO at the flue entrance within time t x The average concentration ; According to C0, And the predicted multiple N is used to obtain C1.

[0034] The time t may be 3 seconds or 5 seconds, and the embodiment of the present invention does not impose any specific limitation thereto.

[0035] The prediction multiple N can be determined according to the delay duration. For example, if the t value is 5s and the delay duration is 200s, the prediction multiple N value = 200 / (5 / 2) = 80.

[0036] According to C0, And the predicted multiple N can be calculated by referring to formula (I): C1=C0+N(C0- ) Formula (I) Among them, C0, And the unit of C1 is mg / Nm 3 ,mg / Nm 3 It refers to the mass of a substance in milligrams per standard cubic meter of gas. Standard cubic meter refers to the unit of volume under standard conditions (temperature 273.15K, pressure 101.325kPa).

[0037] According to some embodiments of the present invention, "determining the injection amount of the reducing agent in the flue according to the prediction data" comprises the following steps: according to C1, C2, Q and V m The injection amount of reducing agent m is obtained, where C2 is NO x Emission control target value, Q is the standard dry flue gas volume, V m is the molar ratio of ammonia to nitrogen.

[0038] NO x The emission control target value C2 refers to the NO emission allowed to be emitted from a certain emission source or within a certain area under specific environmental management requirements. x For example, for the glass industry, NO x Emission control target value ≤ 200mg / Nm 3 .

[0039] Standard dry flue gas volume Q is the volume flow of dry flue gas (flue gas without water vapor) under standard conditions (101.325kPa, 0℃), and is an important indicator for measuring flue gas emissions. In actual measurements, the state of flue gas (temperature, pressure, humidity, etc.) is complex and changeable. In order to facilitate comparison and unify standards, it is necessary to convert the flue gas volume under actual working conditions into the volume of dry flue gas under standard conditions (standard dry flue gas volume). The unit of standard dry flue gas volume Q can be cubic meters per hour (m³ / h) or standard cubic meters per hour (Nm³ / h).

[0040] Ammonia nitrogen molar ratio V m It refers to the reaction between the injected reducing agent (ammonia or urea) and NO in the flue gas. x The ratio of the amount of substance is generally between 0.5-1.

[0041] According to C1, C2, Q and V m The injection amount m of the reducing agent can be calculated by referring to formula (II): Formula (II) Among them, the unit of C1 and C2 is mg / Nm 3, the unit of Q is Nm 3 / h, the unit of m is kg / h, 46 is the molecular weight of nitrogen dioxide (NO2), and 17 is the molecular weight of ammonia (NH3).

[0042] According to some embodiments of the present invention, "determining the injection amount of the reducing agent in the flue according to the prediction data" further includes the following steps: correcting m according to the correction coefficient K.

[0043] The injection amount of reducing agent m is obtained according to theoretical calculation. Since some parameters in theoretical calculation are fixed values ​​(such as standard dry flue gas volume Q), the actual operation process needs to be corrected due to parameter changes (such as flue gas volume changes, instrument drift, catalytic efficiency, etc.). The correction coefficient is obtained by the ratio of the actual reducing agent dosage to the theoretical reducing agent dosage. The actual ammonia consumption can be manually controlled by ammonia injection to obtain the hourly ammonia consumption, which can be averaged for 3h or 5h continuously. The correction coefficient K=m 实际氨耗 / m 理论氨耗 .

[0044] A correction coefficient is set for the injection amount m of the reducing agent to make corrections according to the efficiency of the catalyst at different stages, thereby ensuring that the reducing agent and the flue gas react within a certain high ratio range.

[0045] According to some embodiments of the present invention, the standard dry flue gas volume Q is calculated by the natural gas consumption V 天然气 , Heavy oil consumption m 重油 And the amount of petroleum coke m 石油焦 get.

[0046] The standard dry flue gas volume Q can be calculated by referring to formula (III): Q=V 天然气 ×16.15+m 重油 ×21323.08+m 石油焦 ×20838.46 Formula (III) Among them, V 天然气 The unit is m 3 / h,m 重油 The unit is t / h, m 石油焦 The unit is t / h. 16.15, 21323.08 and 20838.46 represent the smoke generation coefficients of the three fuel combustion respectively. The smoke generation coefficient of fuel combustion refers to the amount of smoke generated after the unit mass (or volume) of fuel is completely burned. It can be calculated based on the excess air coefficient, and the coefficient varies for different kilns.

[0047] Natural gas, heavy oil and petroleum coke are commonly used fuels for boilers. When natural gas, heavy oil and petroleum coke are burned, chemical reactions will occur and flue gas will be produced. Natural gas is a gaseous fuel mainly composed of methane. Its combustion reaction equation is CH4+2O2=CO2+2H2O. It can be seen that for every 1 volume of methane burned, 1 volume of carbon dioxide and 2 volumes of water vapor will be produced, and 2 volumes of oxygen will be consumed at the same time. Oxygen comes from the air. After combustion, a large amount of nitrogen and other gases will be mixed to form flue gas. Heavy oil and petroleum coke are complex mixtures of hydrocarbons and impurities. When they burn, they will also react with oxygen according to the carbon, hydrogen and other elements in their components to generate carbon dioxide, water vapor and other combustion products, and will form flue gas containing multiple components due to the participation of air. Therefore, the standard dry flue gas volume Q can be obtained according to the amount of natural gas, heavy oil and petroleum coke used.

[0048] According to some embodiments of the present invention, reference Figure 2 As shown, the present invention provides an ammonia injection control device 100, comprising: a smoke detector 11, an ammonia injection component 12 and a control system; the smoke detector 11 is arranged at the flue 200, and is used to monitor the gas composition and parameters in the flue 200 in real time; the ammonia injection component 12 is connected to the flue 200, and is used to inject a reducing agent into the flue 200; the control system is electrically connected to the smoke detector 11 and the ammonia injection component 12, respectively, and is used to obtain prediction data according to the detection data of the smoke detector 11, and determine the injection amount of the reducing agent according to the prediction data; the detection data includes NO at the flue inlet x Concentration C0, the predicted data includes NO at the inlet of the SCR reactor x Concentration C1.

[0049] The gas components in the flue include but are not limited to CO, CO2, SO2, NO x , O2, gas parameters include but are not limited to temperature, pressure, humidity, flow rate, etc.

[0050] The reducing agent can be ammonia or urea, which can reduce NO in the flue gas. x Reduced to N2 and H2O.

[0051] The control system can use a distributed control system (DCS system), which has an intelligent algorithm configuration to adjust the NO x The concentration C0 is used to estimate the NO at the inlet of the SCR reactor. x Concentration C1.

[0052] The DCS system can also have NO x Abnormal concentration alarm function, discharge port NO can be set xThe concentration high and low alarm values. When an alarm occurs, the technicians can adjust the ammonia injection parameters in time or check the inlet and outlet flue gas continuous emission monitoring system (CEMS), ammonia flow meter, ammonia pressure, regulating valve, bypass gate, bypass valve, fuel consumption and other related equipment, and check whether there is a drastic change in the flue gas volume, so as to adjust the discharge port NO x The concentration is controlled within the emission standards.

[0053] The DCS system has an inlet NO x Continuous high value frequency statistics function, the high value and duration required for statistics can be set by yourself to prevent entry NO x Exceeding the denitrification load will lead to poor environmental protection operation stability, easy boiler tube burst, shortened bag life, high environmental resistance and increased power consumption. x Continuously exceeding 2500mg / Nm 3 If it exceeds 3 minutes, it will be recorded once; if it exceeds 6 minutes, it will be recorded twice. The cumulative number of times can be cleared at any time.

[0054] The DCS system also has an exhaust port NO x The continuous low value frequency statistics function can set the required low value and duration to prevent excessive ammonia injection from causing poor environmental protection operation stability, boiler tube bursts, shortened bag life, high environmental resistance and increased power consumption. x Continuously below 150mg / Nm 3 If it exceeds 3 minutes, it will be recorded once; if it exceeds 6 minutes, it will be recorded twice. The cumulative number of times can be cleared at any time.

[0055] The DCS system also has the function of automatically calculating the hourly molar ratio and daily molar ratio. When the input value of the ammonia nitrogen molar ratio changes, the hourly average value can be calculated. =[(C0-C2) × Q × 10 -6 / 46]:(m / 17).

[0056] Electrical connection refers to a connection relationship between devices established through wires or other means that can transmit current, electrical signals or data, that is, the detection data of the smoke detector 11 can be transmitted to the control system, and the control system then sends a signal to the ammonia spray component 12, and the ammonia spray component 12 responds according to the signal.

[0057] According to some embodiments of the present invention, the ammonia injection assembly 12 includes a delivery main pipe and at least one ammonia injection grid, the delivery main pipe is provided with a regulating valve, the regulating valve is electrically connected to the control system to adjust the injection amount of the reducing agent according to the opening of the regulating valve; the ammonia injection grid is connected to the delivery main pipe, and a nozzle is provided on the ammonia injection grid.

[0058] The delivery main pipe is used to connect with the ammonia supply system to deliver ammonia to the ammonia injection grid. The ammonia injection grid is composed of multiple groups of ammonia injection pipes arranged in a certain layout. The ammonia injection pipes are provided with nozzles to spray ammonia evenly into the flue. There are no restrictions on the number, position and angle of the nozzles. Different layout methods can be selected according to system requirements, such as matrix type, partition type, etc.

[0059] A regulating valve can be provided to adjust the amount of ammonia. The regulating valve is electrically connected to the control system, which means that the regulating valve is an electrically controlled valve, and the control system can control the opening of the regulating valve through an electronic signal. Exemplarily, the regulating valve can be a solenoid valve.

[0060] According to some embodiments of the present invention, the flue gas detector 11 is disposed at the entrance of the flue 200 ; and / or the ammonia injection assembly 12 is disposed at the inlet of the SCR reactor 300 .

[0061] refer to Figure 2 As shown, one end of the flue 200 is connected to the SCR reactor 300, and the other end is connected to the combustion equipment (not shown). The end of the flue 200 connected to the combustion equipment is the inlet end, and the end connected to the SCR reactor 300 is the outlet end. The smoke detector 11 is arranged at the entrance of the flue 200, which means that the smoke detector is arranged close to the combustion equipment. In this way, the smoke component information just discharged from the combustion equipment (boiler, etc.) can be quickly obtained, and the combustion status can be fed back in time to facilitate adjustments. For example, if the smoke detector 11 detects that the CO content is too high, this may mean that the combustion is incomplete, and the combustion conditions need to be adjusted in time, such as increasing the air supply, etc., to improve the combustion efficiency and reduce energy waste and pollutant generation.

[0062] The ammonia spraying assembly 12 is arranged at the inlet of the SCR reactor 300, and can utilize the airflow in the flue 200 to evenly disperse the ammonia and the flue gas. After entering the SCR reactor 300, the ammonia and NO are separated by the catalyst. x It can react more evenly, thus improving the denitrification efficiency.

[0063] According to some embodiments of the present invention, the control system includes an autonomous adjustment module and a passive shutdown module. The autonomous adjustment module is used to obtain prediction data based on the detection data of the smoke detector 11, and to regulate the injection amount of the reducing agent based on the prediction data; the passive shutdown module is used to delay the shutdown of the ammonia injection component 12 according to the action signal of the combustion equipment.

[0064] The autonomous adjustment module is used to obtain prediction data based on the detection data of the smoke detector 11 and adjust the injection amount of the reducing agent based on the prediction data. The autonomous adjustment module is electrically connected to the smoke detector 11 and the ammonia injection component 12. The C0 signal detected by the smoke detector 11 is transmitted to the autonomous adjustment module. The autonomous adjustment module calculates C1 based on C0, and sends an opening adjustment instruction to the regulating valve of the ammonia injection component 12 based on C1, thereby realizing autonomous adjustment of the injection amount.

[0065] The passive closing module is provided with parameters such as the delay time of the delayed ammonia shut-off, the ammonia shut-off opening, and the ammonia shut-off time. When the combustion equipment (such as a glass kiln) sends an action signal similar to the left-right switching of the fire, the passive closing module sends a shut-off instruction to the ammonia spraying component 12. The ammonia shut-off signal of the passive closing module is due to the opening adjustment instruction of the autonomous adjustment module.

[0066] According to some embodiments of the present invention, reference Figure 2 As shown, the present invention further provides an SCR denitration device, including an SCR reactor 300 and the above-mentioned ammonia injection control device 100. The specific configuration of the ammonia injection control device 100 refers to the above-mentioned embodiment. Since the SCR denitration device of the present invention adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0067] In some embodiments, the temperature within the SCR reactor 300 is 350°C-380°C.

[0068] The SCR reactor 300 is filled with a catalyst to x Under the action of the catalyst, it reacts with ammonia to generate nitrogen and water vapor. The main reaction equation is: 4NH3+ 4NO + O2+ 4N2+ 6H2O4NH3+ 2NO2+ O2+3N2+ 6H2O.

[0069] When the temperature in the SCR reactor 300 is between 350°C and 380°C, the activity and selectivity of the catalyst are optimal, and NO in the flue gas can be efficiently converted to x It is converted into nitrogen and water vapor, and at the same time, it can ensure that the ammonium bisulfate is in a gaseous state in the SCR reactor 300, which can effectively ensure that the catalyst is unobstructed. Although too high a temperature helps to increase the reaction rate, the catalyst may burn out, resulting in a decrease in denitration efficiency. Too low a temperature can reduce energy consumption and heat loss, but the activity and selectivity of the catalyst will be affected, resulting in a decrease in denitration efficiency.

[0070] The SCR denitration device in the embodiment of the present invention is applied to the flue gas treatment of a glass enterprise, wherein the reaction temperature in the SCR reactor 300 is 370°C.

[0071] The amount of liquid ammonia used in the first month before the SCR denitration device was put into use was 55.467 tons, and the amount of liquid ammonia used in the first month after it was put into use was 45.209 tons, and the amount of liquid ammonia used was reduced by 10.258 tons, indicating that the SCR denitration system of the present invention can achieve precise ammonia injection control, making the liquid ammonia supply and NO x The treatment needs are matched, thus saving the use of liquid ammonia. x Less than 150mg / Nm 3 The number of times is 394 times / month. After being put into use, the discharge port NO x Less than 150mg / Nm 3 The number of low-standard times is 42 times / month, and the number of low-standard times is significantly reduced, indicating that the SCR denitration device of the embodiment of the present invention operates stably, that is, the ammonia spraying is more uniform, avoiding the situation of excessive or insufficient ammonia in some areas, and improving the overall denitration effect; the wear and blockage of the catalyst layer are reduced, ensuring the long-term effective use of the catalyst. In addition, after the SCR denitration device of the embodiment of the present invention is put into use, the pressure difference of the bag filter at the rear end of the boiler is reduced from 1kpa to 0.8kpa, and the running stability of the fan is also greatly improved.

[0072] The denitrification efficiency of the SCR denitrification device before and after it is put into use is as follows Figure 3 As shown, it can be seen that the SCR denitration device of the present invention can improve the denitration efficiency, and the denitration efficiency can reach up to 92.5% at the highest, and can basically be maintained above 88%.

[0073] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An ammonia injection control method, characterized in that: include: Monitor the gas content in the flue in real time and obtain detection data; Obtaining prediction data according to the detection data, and determining the injection amount of the reducing agent in the flue according to the prediction data; The detection data includes NO at the flue inlet x The predicted data includes the NO concentration C0 at the inlet of the SCR reactor. x Concentration C1.

2. The ammonia injection control method according to claim 1, characterized in that: The “obtaining prediction data according to the detection data” includes: Get the NO at the flue inlet within time t x The average concentration ; According to C0, And the predicted multiple N is used to obtain C1.

3. The ammonia injection control method according to claim 2, characterized in that: The “determining the injection amount of the reducing agent in the flue according to the prediction data” includes: According to C1, C2, Q and V m The injection amount of reducing agent m is obtained, where C2 is NO x Emission control target value, Q is the standard dry flue gas volume, V m is the molar ratio of ammonia to nitrogen.

4. The ammonia injection control method according to claim 3, characterized in that: The standard dry flue gas volume Q is calculated by the natural gas consumption V 天然气 , Heavy oil consumption m 重油 And the amount of petroleum coke m 石油焦 get.

5. The ammonia injection control method according to claim 3, characterized in that: The "regulating the injection amount of the reducing agent in the flue according to the prediction data" also includes: m is corrected according to the correction factor K.

6. An ammonia injection control device, characterized in that: include: The smoke detector is installed at the smoke duct to monitor the gas composition and parameters in the smoke duct in real time; An ammonia spraying assembly is connected to the flue and is used to spray a reducing agent into the flue; The control system is electrically connected to the smoke detector and the ammonia spraying component, respectively, and is used to obtain prediction data according to the detection data of the smoke detector, and determine the injection amount of the reducing agent according to the prediction data; the detection data includes NO x The predicted data includes the NO concentration C0 at the inlet of the SCR reactor. x Concentration C1.

7. The ammonia injection control device according to claim 6, characterized in that: The ammonia injection assembly comprises: A delivery main pipe, wherein a regulating valve is provided on the delivery main pipe, and the regulating valve is electrically connected to the control system to adjust the injection amount of the reducing agent according to the opening of the regulating valve; At least one ammonia injection grid is communicated with the transport main pipe, and a nozzle is arranged on the ammonia injection grid.

8. The ammonia injection control device according to claim 6, characterized in that: The smoke detector is arranged at the entrance of the smoke duct; and / or, The ammonia injection assembly is arranged at the inlet of the SCR reactor.

9. The ammonia injection control device according to claim 6, characterized in that: The control system comprises: An autonomous adjustment module, used to obtain prediction data according to the detection data of the smoke detector, and determine the injection amount of the reducing agent according to the prediction data; The passive closing module is used to delay the closing of the ammonia injection component according to the action signal of the combustion equipment.

10. An SCR denitration device, characterized in that: It comprises an SCR reactor and the ammonia injection control device according to any one of claims 6 to 9.

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