A constant-speed gas generator set full-working-condition SCR control method and system

Abstract

The application provides a constant-speed gas generator set full-condition SCR control method and system, and belongs to the technical field of the constant-speed gas generator set full-condition SCR control, and comprises a three-channel heat exchange pipeline, a sensor assembly and a central controller. One end of the three-channel heat exchange pipeline is connected to a first main pipe, and the other end is connected to a second main pipe. The second main pipe is connected to an ammonia injection system and an SCR treatment system. The three-channel heat exchange pipeline is a high-temperature pipeline, a medium-temperature pipeline and a low-temperature pipeline. The sensor assembly is arranged on the downstream pipeline of the first main pipe, the second main pipe and the SCR treatment system. The central controller controls the opening degree of the channel valve of the high-temperature pipeline, the medium-temperature pipeline and the low-temperature pipeline based on the measured temperature of the sensor assembly, so that the tail gas is always at a suitable temperature of the SCR treatment system.

Description

Technical Field

[0001] This invention belongs to the field of SCR control technology for all operating conditions of gas generator sets, and particularly relates to a constant speed gas generator set SCR control method and system for all operating conditions. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] As the speed of a gas generator set increases, the exhaust gas temperature gradually rises; after reaching a peak exhaust gas temperature, the temperature tends to stabilize at higher speeds. When the speed is constant, the temperature is mainly related to the load. Gas generator sets include gas internal combustion engines and micro gas turbines. These types of units require a strictly constant speed when connected to the grid, such as 50 / 60Hz. Exhaust temperature cannot be adjusted by increasing or decreasing the speed. Therefore, solutions to low-temperature deactivation and high-temperature sintering must rely on load management, waste heat exchange, and supplementary combustion heating.

[0004] SCR is an abbreviation for Selective Catalytic Reduction. SCR technology is used for denitrification of exhaust gas from gas-fired generator sets. By precisely controlling the injection of the reducing agent and the reaction conditions, nitrogen oxides in the exhaust gas are reduced to nitrogen and water under the action of a catalyst, achieving nitrogen oxide emission standards while suppressing ammonia escape and ensuring stable operation of the unit under varying loads. However, the exhaust temperature of gas-fired generator sets varies drastically with the load: under low load / cold start, the temperature is too low, below 200℃, and the SCR catalyst cannot ignite, resulting in direct NOx emissions; under high load, the temperature is too high, above 450℃, which can easily cause catalyst sintering and deactivation, leading to nitrogen oxide emissions and catalyst failure. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a constant speed gas generator set full-condition SCR control method and system. Under the premise of maintaining 100% power generation efficiency without interfering with engine combustion, the exhaust gas entering the SCR is controlled within the optimal window of 250-450℃ through a three-channel exhaust gas heat exchange architecture and timing control logic.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: In the first aspect, a constant speed gas generator set full-condition SCR control system is disclosed, including: a three-channel heat exchange pipeline, a sensor assembly and a central controller; One end of each of the three-channel heat exchange pipes is connected to the first main pipe, and the other end is connected to the second main pipe; the second main pipe is connected to the ammonia injection system and the SCR treatment system respectively. The three-channel heat exchange pipelines are respectively a high-temperature pipeline, a medium-temperature pipeline, and a low-temperature pipeline; The sensor assemblies are respectively installed in the first main pipe, the second main pipe and the downstream pipe of the SCR processing system; The central controller controls the opening degree of the channel valves of the high-temperature, medium-temperature, and low-temperature pipelines based on the temperature measured by the sensor components, so that the exhaust gas is always at the appropriate temperature of the SCR treatment system.

[0007] As a further technical solution, the sensor assembly includes: A temperature sensor, installed in the first main pipe, is used to measure the temperature of the exhaust gas entering the three-channel heat exchange pipe. The first flow sensor, installed in the first main pipe, is used to measure the flow rate of the exhaust gas entering the three-channel heat exchange pipe. The second flow sensor, installed in the second main pipe, is used to measure the exhaust gas flow rate entering the SCR treatment system. The first NOx concentration sensor, installed in the second manifold, is used to measure the NOx concentration upstream of the SCR treatment system; The second NOx concentration sensor is installed in the downstream pipeline of the SCR treatment system to measure the NOx concentration downstream of the SCR treatment system. An NH3 sensor is installed in the downstream pipeline of the SCR treatment system to measure the NH3 concentration downstream of the SCR treatment system.

[0008] As a further technical solution, a first valve is provided at one end of the cryogenic pipeline, and a fourth valve is provided at the other end; A second valve is installed at one end of the medium-temperature pipeline, and a fifth valve is installed at the other end; The high-temperature pipeline is equipped with a third valve at one end and a sixth valve at the other end.

[0009] Secondly, a constant-speed gas generator set under all operating conditions SCR control method is disclosed, including: If the initial temperature of the exhaust gas is in the low-temperature zone, open the low-temperature pipeline valve and close other channel valves to temporarily store the low-temperature exhaust gas in the low-temperature pipeline and expansion chamber. When the exhaust gas gradually heats up to the SCR activation temperature, close the low-temperature channel valve. If the initial temperature of the exhaust gas is in the medium temperature range, open the valve of the medium temperature pipeline, and open the channel valve at the end of the low temperature pipeline proportionally according to the value of the exhaust gas inlet temperature sensor to exchange the low temperature gas to the corresponding temperature for SCR treatment. After all the low temperature gas has been treated, close the channel valve of the low temperature pipeline. If the initial temperature of the exhaust gas is in the high-temperature zone, heat exchange occurs through the high-temperature channel and the medium-temperature channel. The proportion of heat exchange gas required is calculated based on the exhaust gas temperature. The high-temperature channel controls the amount of heat exchange gas to exchange heat with the outside environment through a gas valve, and finally mixes with the exhaust gas in the medium-temperature channel.

[0010] As a further technical solution, if the initial temperature of the exhaust gas is in the low-temperature zone, the temperature of the low-temperature pipeline can be predicted based on the values ​​of the first flow sensor and temperature sensor, as well as the duration.

[0011] As a further technical solution, the prediction of the temperature of the cryogenic pipeline includes: Calculate the enthalpy increment of the gas flowing into the cryogenic pipeline at the current moment; Next, calculate the total enthalpy of the gas in the cryogenic pipeline; The new average temperature after mixing is calculated based on the enthalpy increment and the total enthalpy of the gas. The new average temperature after mixing is used as the predicted low-temperature exhaust gas temperature.

[0012] As a further technical solution, it also includes: After obtaining the low-temperature exhaust gas temperature T1, the fourth valve can be controlled based on the medium-temperature exhaust gas temperature T2 to mix with the medium-temperature exhaust gas. The valve opening of the medium-temperature pipeline is fully open. To ensure normal SCR operation, the valve opening of K4 is as follows: k1=(T2-T0) / T1 Where T0 is the set SCR processing temperature.

[0013] As a further technical solution, if the initial temperature of the exhaust gas is in the high-temperature zone, assuming the high-temperature exhaust gas temperature is T3 and the temperature after heat exchange with the outside is T4, then the equations can be solved simultaneously. K2+K3=1 K2T3-K3T4=T0 The openings of K2 and K3 can be obtained.

[0014] As a further technical solution, when the ammonia injection system injects ammonia, the amount of ammonia injected is determined based on the measured NOx concentration upstream of the SCR treatment system.

[0015] As a further technical solution, the ammonia injection rate is determined based on the measured NOx concentration upstream of the SCR treatment system, specifically including: Based on the upstream NOx concentration, the basic ammonia injection amount is calculated according to the stoichiometric ratio of the chemical reaction. Then, a closed-loop correction is performed based on the real-time feedback of the downstream NOx and ammonia concentrations: if the downstream NOx concentration is too high, the ammonia injection amount is increased; if ammonia escape exceeds the limit, the ammonia injection amount is reduced or the load / air-fuel ratio is finely adjusted through the GCU to change the exhaust composition.

[0016] The above one or more technical solutions have the following beneficial effects: This embodiment of the sub-technical solution, without interfering with engine combustion (maintaining 100% power generation efficiency), uses a three-channel exhaust gas heat exchange architecture and timing control logic to control the amount of ammonia injected to near the chemical stoichiometry ratio, and precisely locks the exhaust gas entering the SCR within the optimal window of 250-450℃.

[0017] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the method flow of an embodiment of the present invention. Detailed Implementation

[0020] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0022] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0023] SCR (Selective Catalytic Reduction) primarily controls two parameters: temperature and ammonia injection rate. Excessive ammonia injection leads to ammonia waste and escape pollution, while insufficient injection results in excessive NOx emissions. Temperature mainly affects the catalyst's efficiency; current practice generally avoids ammonia injection when catalytic efficiency is low to prevent ammonia escape and further pollution. The ammonia injection rate corresponds to the amount of nitrogen oxides reacting; optimal results are achieved when both are close to their stoichiometric ratio. Both insufficient and excessive ammonia injection cause pollution. The challenge lies in controlling the ammonia injection rate—specifically, how to maintain it near the stoichiometric ratio.

[0024] Example 1 This embodiment discloses a constant-speed gas generator set SCR control system under all operating conditions. See attached document. Figure 1 ,include: Three-channel heat exchange pipes, sensor assembly and central controller; One end of the three-channel heat exchange pipe is connected to the first main pipe, and the other end is connected to the second main pipe; the second main pipe is connected to the ammonia injection system and the SCR treatment system; the three-channel heat exchange pipes are high-temperature pipe, medium-temperature pipe and low-temperature pipe respectively; The sensor assemblies are respectively installed in the first main pipe, the second main pipe, and the downstream pipe of the SCR processing system; The central controller controls the opening degree of the channel valves of high-temperature, medium-temperature and low-temperature pipelines based on the temperature measured by the sensor components, so as to keep the exhaust gas at the appropriate temperature of the SCR treatment system.

[0025] In this embodiment, the first main pipe is the exhaust gas main pipe, and the second main pipe is the exhaust gas treatment pipe.

[0026] The above technical solution avoids the conventional approach of "not injecting ammonia when the exhaust gas temperature is too low to meet the SCR conditions, which would cause further pollution." This embodiment's sub-solution stores the low-temperature exhaust gas, allowing it to exchange heat with the high-temperature gas, thus bringing it to a reasonable temperature range.

[0027] In one embodiment, the sensor assembly described above includes: A temperature sensor, installed in the first main pipe, is used to measure the temperature of the exhaust gas entering the three-channel heat exchange pipe. The first flow sensor, installed in the first main pipe, is used to measure the flow rate of the exhaust gas entering the three-channel heat exchange pipe. The second flow sensor, installed in the second main pipe, is used to measure the exhaust gas flow rate entering the SCR treatment system. The first NOx concentration sensor, installed in the second manifold, is used to measure the NOx concentration upstream of the SCR treatment system; The second NOx concentration sensor is installed in the downstream pipeline of the SCR treatment system to measure the NOx concentration downstream of the SCR treatment system. An NH3 sensor is installed in the downstream pipeline of the SCR treatment system to measure the NH3 concentration downstream of the SCR treatment system.

[0028] By setting up the above sensor components, the temperature, flow rate, NOx concentration, and NH3 concentration at the desired location can be obtained, which facilitates subsequent temperature control.

[0029] In one embodiment, a first valve is installed at one end of the aforementioned cryogenic pipeline, and a fourth valve is installed at the other end; A second valve is installed at one end of the medium-temperature pipeline, and a fifth valve is installed at the other end; A third valve is installed at one end of the high-temperature pipeline, and a sixth valve is installed at the other end.

[0030] The valves described above facilitate the control of exhaust gas entering the required pipeline for heat exchange, ultimately achieving the required exhaust gas temperature for effective subsequent treatment in the SCR system.

[0031] This embodiment's sub-solution does not interfere with the combustion process, but rather manages the heat of the exhaust gas: ensuring the engine always operates within its highest efficiency range, and then precisely controlling the temperature of the gas entering the SCR through an exhaust gas heat exchanger. The exhaust manifold is connected to three corresponding pipes via three gas valves K1, K2, and K3, and finally merges into the SCR exhaust gas treatment pipe through K4, K5, and K6. The central controller uses PWM to control the opening and degree of opening of these six pipe valves. An SCR inlet temperature sensor is installed before the three-channel heat exchange pipe to measure the initial exhaust gas temperature and control the opening degree of the six gas valves based on this temperature. The central controller implements state machine control logic based on temperature ranges and PID closed-loop control based on NOx / NH3 ammonia injection quantity.

[0032] Example 2 See appendix Figure 2 As shown, the purpose of this embodiment is to provide a constant-speed gas generator set SCR control method under all operating conditions, including: Data from the exhaust gas temperature sensor is acquired and categorized into low-temperature, medium-temperature, and high-temperature zones based on whether the exhaust gas temperature is within the optimal SCR response temperature range. The zone is defined as follows: exhaust gas temperature below the optimal SCR response temperature range is the low-temperature zone; within the optimal SCR response temperature range is the medium-temperature zone; and above the optimal SCR temperature range is the high-temperature zone. Low-temperature zone (<250℃): Instead of simply prohibiting direct ammonia emission, forced rapid heating (such as inlet preheating) is implemented, and the low-temperature channel valve K1 is opened while other channel valves are closed. The low-temperature exhaust gas is temporarily stored in the low-temperature pipeline and expansion chamber. During subsequent high-load, high-temperature gas emission, heat exchange with the low-temperature gas is achieved, allowing the low-temperature gas to reach the SCR temperature. The low-temperature period is generally short-lived, only occurring during the cold start phase. When the exhaust gas gradually heats up to the SCR activation temperature, channel valve K1 can be closed. Once the emitted exhaust gas reaches the medium-temperature gas level, K4 and K5 are opened to achieve heat exchange. After heat exchange, the gas reaches the appropriate SCR temperature and then enters the SCR treatment system together.

[0033] After closing channel valve K1, when the exhaust gas temperature is in the medium temperature range, open K4, K2, and K5. The low-temperature gas will flow into the SCR treatment system. The exhaust gas will also flow into the SCR treatment system through K2 and K5, completing the heat exchange treatment of the low-temperature gas.

[0034] Medium temperature zone (250-450℃): This temperature is the optimal operating window for SCR. At this time, valves K2 and K5 in the medium temperature pipeline can be opened directly. According to the value of the exhaust gas inlet temperature sensor, the channel valve K4 at the low temperature end can be opened proportionally to exchange the heat of the low temperature gas stored in the low temperature pipeline to the corresponding temperature for SCR treatment. The temperature here is the temperature of the gas after the medium temperature gas and the low temperature gas are mixed, so that it reaches the appropriate temperature for SCR catalysis. After all the low temperature gas has been treated, the low temperature channel valve K4 is closed.

[0035] High-temperature zone (>450℃): Temperature is controlled by an exhaust gas heat exchange device, maintaining 100% power generation efficiency without changing engine combustion parameters. Exhaust gas heat exchange occurs through high-temperature and medium-temperature channels. The required proportion of heat exchange gas is calculated based on the exhaust gas temperature. The high-temperature channel controls the amount of heat exchange gas to exchange heat with the outside environment via gas valve K3, and finally mixes with the exhaust gas from the medium-temperature channel. In this way, the exhaust gas treated by SCR can function within the appropriate temperature range for the catalyst.

[0036] Based on the above method, by controlling the on / off state and proportional control of the three-channel valve, the exhaust gas can always be kept at the appropriate temperature for SCR treatment.

[0037] In terms of specific implementation, the next step is the corresponding temperature control strategy, the purpose of which is to maintain the exhaust gas temperature within the SCR catalytic range. Since the exhaust gas temperature and flow rate are constantly changing, the temperature of the cryogenic pipeline will also change. Using a single temperature sensor to measure the total temperature of the gas in the cryogenic pipeline at a single point will result in inaccurate data due to uneven mixing. Therefore, for the exhaust gas in the cryogenic pipeline, the temperature T1 of the cryogenic pipeline is predicted based on the values ​​of the flow sensor and temperature sensor, as well as the duration, to facilitate heat exchange with the medium-temperature zone.

[0038] First, calculate the enthalpy increment of the gas flowing into the cryogenic pipe at the current moment.

[0039] Let be the mass flow rate at time t. The specific heat capacity at constant pressure of the exhaust gas. Let be the exhaust gas temperature at time t. The shorter the sampling time, the more accurate the calculation, but the greater the computing load and the more prone it is to oscillation.

[0040]

[0041] in, This refers to the total mass of the gas stored in the cryogenic pipeline. The average temperature of the cryogenic gas in the pipeline at the previous moment. This represents the total enthalpy of the gas already inside the pipeline.

[0042] The new average temperature after the newly introduced cryogenic gas and the original cryogenic gas in the cryogenic pipeline mix is:

[0043] in, The total mass after mixing is used to calculate the total temperature of the cryogenic gas in the cryogenic pipeline using the above formula.

[0044] The new average temperature after mixing is used as the predicted low-temperature exhaust gas temperature T1. Knowing the low-temperature exhaust gas temperature T1, valve K4 can be controlled to mix with the medium-temperature exhaust gas based on the medium-temperature exhaust gas temperature T2. The valve opening of the medium-temperature pipeline is fully open. To ensure the normal operation of the SCR treatment system, the valve opening of K4 is... k1=(T2-T0) / T1 T0 is the set SCR treatment temperature, and the medium-temperature exhaust gas temperature T2 is obtained through the exhaust gas temperature sensor. The function of the exhaust gas temperature sensor is to determine which temperature range the exhaust gas belongs to based on the exhaust gas temperature. Gases below the SCR treatment system reaction temperature zone are low-temperature gases, those in the SCR treatment system reaction temperature zone are medium-temperature gases, and those above the SCR treatment system reaction temperature zone are high-temperature gases.

[0045] In high-temperature exhaust gas treatment, the exhaust gas temperature also needs to be controlled to reach the SCR treatment temperature. This requires controlling the opening degrees of K2 and K3. Assuming the high-temperature exhaust gas temperature is T3, and the temperature after heat exchange between the high-temperature channel and the heat exchanger is T4, the following equations can be established simultaneously. K2+K3=1 K2T3-K3T4=T0 The opening degrees of valves K2 and K3 are determined. When the exhaust gas temperature sensor detects high-temperature gas, valves K2 and K3 will open. Part of the exhaust gas from valve K3 flows into the high-temperature channel, where it exchanges heat with the outside environment to reach a low temperature (T4). The other part flows directly to the SCR treatment system through valve K2, without participating in heat exchange. Finally, these two gas streams merge and exchange heat to reach the SCR treatment system's reaction temperature (T0). To ensure that the heat exchange reaches the SCR treatment system's reaction temperature (T0), the opening degrees of valves K2 and K3 need to be controlled. Based on the opening degrees of valves K2 and K3, the amount of gas flowing into the high-temperature and medium-temperature channels is controlled.

[0046] Therefore, K2 + K3 = 1 represents the complete flow of gas into K2 and K3, with no gas flowing to other pipes. K2T3 - K3T4 = T0 represents the process where the two gas streams rejoin and exchange heat to reach the SCR treatment system's reaction temperature T0. By solving the above system of equations, the opening degrees of K2 and K3 can be obtained.

[0047] In summary, when the exhaust gas temperature sensor detects that the gas is in the low-temperature zone, K1 opens and other valves close, so no gas flows to the SCR treatment system.

[0048] In the medium temperature range, K1, K3, and K6 will be closed, while K2, K4, and K5 will be opened. This ensures that the exhaust gas flows into the SCR while also allowing the stored low-temperature gas to be processed by opening K4.

[0049] In the high-temperature zone, K1 and K4 will be closed, and the other four valves will be opened to process the high-temperature gas. At this time, the exhaust gas flows from K2 and K3 into the medium-temperature pipeline and the high-temperature pipeline respectively, and then flows into the SCR treatment system from K5 and K6 respectively.

[0050] Therefore, the opening of different channel valves is determined based on the value of the exhaust gas temperature sensor, all in order to ensure that the exhaust gas temperature after three-channel treatment meets the temperature requirements of the SCR treatment washing system.

[0051] Finally, the exhaust gas enters the SCR system after passing through the valves in the three-channel system. Ammonia injection is required to react with the exhaust gas and eliminate nitrogen oxides. The key is calculating the ammonia injection amount to prevent over-injection. This ammonia injection amount is determined by measuring the nitrogen oxide concentration using the nitrogen oxide concentration sensor after the valve is opened.

[0052] For ammonia injection control, a simple PID closed-loop control is adopted, implementing a feedforward + feedback composite ammonia injection control. First, based on the upstream NOx sensor readings, the basic ammonia injection quantity is calculated according to the stoichiometric ratio (feedforward). Then, closed-loop correction is performed based on real-time feedback from the downstream NOx and ammonia sensors: if downstream NOx levels are high, the ammonia injection quantity is increased; if ammonia escape exceeds the limit, the ammonia injection quantity is reduced or the load / air-fuel ratio is fine-tuned through the GCU to change the exhaust composition. This achieves the goal of "clean treatment without wasting ammonia." Because the temperature is constant, the ammonia-nitrogen molar ratio (ANR) can be set constant at its optimal value without drastic adjustments with temperature, reducing the difficulty of control coupling.

[0053] When calculating the basic ammonia injection rate based on the stoichiometric ratio of chemical reactions, SCR denitrification involves two reactions: ammonia and nitric oxide and nitrogen dioxide: 4NO + 4NH3 + O2 → 4N2 + 6H2O; 2NO + 2NO2 + 4NH3 → 4N2 + 6H2O; the molar ratio is 1:1; n(NO x Molar flow rate) = [Flue gas flow rate × NO] x Concentration × 10 -6 ] ÷ NO x molar mass of NO; x The molar mass is taken as 30 kg / kmol in engineering; n (NH3 molar flow rate) = ammonia flow rate (Nm³ / h) ÷ 22.4; N represents the flow rate under standard conditions.

[0054] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0055] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A constant-speed gas generator set with full-condition SCR control system, characterized in that, include: Three-channel heat exchange pipes, sensor assembly and central controller; One end of each of the three-channel heat exchange pipes is connected to the first main pipe, and the other end is connected to the second main pipe; the second main pipe is connected to the ammonia injection system and the SCR treatment system respectively. The three-channel heat exchange pipelines are respectively a high-temperature pipeline, a medium-temperature pipeline, and a low-temperature pipeline; The sensor assemblies are respectively installed in the first main pipe, the second main pipe and the downstream pipe of the SCR processing system; The central controller controls the opening degree of the channel valves of the high-temperature, medium-temperature, and low-temperature pipelines based on the temperature measured by the sensor components, so that the exhaust gas is always at the appropriate temperature of the SCR treatment system.

2. The constant speed gas generator set full-condition SCR control system as described in claim 1, characterized in that, The sensor assembly includes: A temperature sensor, installed in the first main pipe, is used to measure the temperature of the exhaust gas entering the three-channel heat exchange pipe. The first flow sensor, installed in the first main pipe, is used to measure the flow rate of the exhaust gas entering the three-channel heat exchange pipe. The second flow sensor, installed in the second main pipe, is used to measure the exhaust gas flow rate entering the SCR treatment system. The first NOx concentration sensor, installed in the second manifold, is used to measure the NOx concentration upstream of the SCR treatment system; The second NOx concentration sensor is installed in the downstream pipeline of the SCR treatment system to measure the NOx concentration downstream of the SCR treatment system. An NH3 sensor is installed in the downstream pipeline of the SCR treatment system to measure the NH3 concentration downstream of the SCR treatment system.

3. The constant speed gas generator set full-condition SCR control system as described in claim 1, characterized in that, The cryogenic pipeline is equipped with a first valve at one end and a fourth valve at the other end; A second valve is installed at one end of the medium-temperature pipeline, and a fifth valve is installed at the other end; The high-temperature pipeline is equipped with a third valve at one end and a sixth valve at the other end.

4. A constant-speed gas generator set with full-condition SCR control method, characterized in that, include: If the initial temperature of the exhaust gas is in the low-temperature zone, open the low-temperature pipeline valve and close other channel valves to temporarily store the low-temperature exhaust gas in the low-temperature pipeline and expansion chamber. When the exhaust gas gradually heats up to the SCR activation temperature, close the low-temperature pipeline valve. If the initial temperature of the exhaust gas is in the medium temperature range, open the valve of the medium temperature pipeline, and open the channel valve at the end of the low temperature pipeline proportionally according to the value of the exhaust gas inlet temperature sensor to exchange the low temperature gas to the corresponding temperature for SCR treatment. After all the low temperature gas has been treated, close the channel valve of the low temperature pipeline. If the initial temperature of the exhaust gas is in the high-temperature zone, heat exchange occurs through the high-temperature channel and the medium-temperature channel. The proportion of heat exchange gas required is calculated based on the exhaust gas temperature. The high-temperature channel controls the amount of heat exchange gas to exchange heat with the outside environment through a gas valve, and finally mixes with the exhaust gas in the medium-temperature channel.

5. The constant speed gas generator set full-condition SCR control method as described in claim 4, characterized in that, If the initial temperature of the exhaust gas is in the low-temperature zone, the temperature of the low-temperature pipe is predicted based on the values ​​of the first flow sensor and temperature sensor, as well as the duration.

6. The constant speed gas generator set full-condition SCR control method as described in claim 5, characterized in that, The process of predicting the temperature of the cryogenic pipeline includes: Calculate the enthalpy increment of the gas flowing into the cryogenic pipeline at the current moment; Next, calculate the total enthalpy of the gas in the cryogenic pipeline; The new average temperature after mixing is calculated based on the enthalpy increment and the total enthalpy of the gas. The new average temperature after mixing is used as the predicted low-temperature exhaust gas temperature.

7. The constant speed gas generator set full-condition SCR control method as described in claim 4, characterized in that, it further... include: After obtaining the low-temperature exhaust gas temperature T1, the fourth valve can be controlled based on the medium-temperature exhaust gas temperature T2 to mix with the medium-temperature exhaust gas. The valve opening of the medium-temperature pipeline is fully open. To ensure normal SCR operation, the valve opening of K4 is as follows: k1=(T2-T0) / T1 Where T0 is the set SCR processing temperature.

8. The constant speed gas generator set full-condition SCR control method as described in claim 4, characterized in that, If the initial temperature of the exhaust gas is in the high-temperature zone, assuming the high-temperature exhaust gas temperature is T3 and the temperature after heat exchange with the outside is T4, then the equations can be solved simultaneously. K2+K3=1 K2T3-K3T4=T0 The openings of K2 and K3 can be obtained.

9. The constant speed gas generator set full-condition SCR control method as described in claim 4, characterized in that, When the ammonia injection system injects ammonia, the injection rate is determined based on the measured NOx concentration upstream of the SCR treatment system.

10. The constant speed gas generator set full-condition SCR control method as described in claim 9, characterized in that, The ammonia injection rate is determined based on the measured NOx concentration upstream of the SCR treatment system, specifically including: Based on the upstream NOx concentration, the basic ammonia injection amount is calculated according to the stoichiometric ratio of the chemical reaction. Then, a closed-loop correction is performed based on the real-time feedback of the downstream NOx and ammonia concentrations: if the downstream NOx concentration is too high, the ammonia injection amount is increased; if ammonia escape exceeds the limit, the ammonia injection amount is reduced or the load / air-fuel ratio is finely adjusted through the GCU to change the exhaust composition.

Images