Method for judging and disposing abnormity of dry quenching flue gas desulfurization system

Abstract

The invention discloses a dry quenching flue gas desulfurization system abnormity judgment and disposal method. The method comprises an abnormity judgment stage, an emergency disposal stage and a system recovery stage. According to the method, the rapid abnormity judgment is realized by monitoring the pressure change gradient of the pre-storage chamber, the current fluctuation of the desulfurization fan and the interlocking shutdown signal verification in real time; differentiated emergency disposal strategies are adopted according to characteristics of different areas; and rapid system recovery is realized through soft start control and parameter recovery optimization control. The method has the advantages of short fault response time, high pressure control precision, short system recovery time, low energy consumption and the like, and is suitable for a dry quenching process desulfurization system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coke dry quenching process, in particular to a coke dry quenching flue gas desulfurization system abnormality determination and disposal method. BACKGROUND

[0002] The coke dry quenching flue gas has the characteristics of multiple and dispersed pollution sources of sulfur dioxide and smoke dust, and because the temperature and pollutant concentration of the coke dry quenching flue gas are irregularly distributed, the temperature and pollutant concentration of the coke dry quenching flue gas will dynamically change as the coke charging operation progresses, so the control and collection of the coke dry quenching flue gas have extremely high concentration.

[0003] Because the temperature of the coke dry quenching pre-storage section diffused flue gas and the coke discharge site diffused flue gas is low and does not reach the dry desulfurization temperature requirement, a separate desulfurization and denitrification system is independently set, which requires a large investment. Therefore, the coke dry quenching system of TISCO merges the diffused flue gas into the coke oven flue gas desulfurization and denitrification system for purification, and the diffused flue gas of the coke dry quenching is mixed with the coke oven flue gas for desulfurization treatment. The temperature of the flue gas at the outlet of the coke dry quenching circulating fan is 160-180℃, and the pressure is 5.3KPa. Based on the above parameters, the flue gas is taken from the outlet pipeline of the circulating gas fan of the coke dry quenching and introduced into the desulfurization device, which solves the problem of low flue gas temperature of the coke dry quenching pre-storage section diffused flue gas and meets the temperature requirement of desulfurization.

[0004] Because the pressure of the flue gas discharged by the coke dry quenching is relatively low, the coke oven desulfurization and denitrification is far away from the coke dry quenching, and the suction of the induced draft fan is insufficient, a separate dust removal pretreatment system is needed before merging into the coke oven flue gas main pipeline. The diffused flue gas is first introduced into the anti-explosion bag type dust collector for smoke dust purification before entering the desulfurization and denitrification system, and the particulate matter (coke powder) in the flue gas is filtered and removed. In the prior art, the coke dry quenching flue gas desulfurization system has the following main technical defects: 1. Long abnormal condition determination response time: the traditional fault determination method relies on manual confirmation, and the average time consumption is 10-20 minutes. 2. Poor pressure control accuracy: the pre-storage chamber pressure fluctuation range exceeds ±200Pa, affecting the stable operation of the system. 3. Low system recovery efficiency: the conventional recovery time is more than 60 minutes, resulting in a decrease in production efficiency. 4. Lack of regional differentiation regulation: the process parameter difference between the north and south areas is not fully considered. 5. High energy consumption: the traditional control method leads to additional energy waste.

[0005] In order to overcome the above technical defects, the present application proposes an abnormality determination method based on multi-parameter linkage and a regional differentiation emergency disposal strategy, which can significantly improve the system operation reliability. It has the following advantages: 1. The fault response time is shortened to within 45 seconds. 2. The pressure control accuracy is improved to ±50Pa. 3. The system recovery time is compressed to 35 minutes. 4. The energy consumption is reduced by 12-15%. 5. Regional differentiation precise regulation is achieved. 6. The system operation reliability is improved. SUMMARY

[0006] The present application aims at the above-mentioned problems, and provides a dry quenching flue gas desulfurization system abnormality judgment and disposal method.

[0007] The present application is achieved in the following way: a dry quenching flue gas desulfurization system abnormality judgment method, comprising the following steps: step one: the DCS system monitors the pre-stored chamber pressure change gradient in real time, and triggers a first-level alarm when the pressure change speed ΔP / Δt is greater than or equal to 50 Pa / s, wherein ΔP is the pressure value, the unit is Pa, and Δt is the time, the unit is second; step two: after the first-level alarm is triggered, the desulfurization fan current fluctuation is detected synchronously, and a current sudden drop greater than or equal to 30% triggers a second-level alarm, and the main control personnel and the on-site personnel need to confirm the running state of the desulfurization fan; step three: an interlocking shutdown signal verification, i.e. abnormal shutdown of the desulfurization fan, triggers a third-level alarm, and the corresponding dry quenching furnace loading device is locked.

[0008] An abnormal treatment method of a dry quenching flue gas desulfurization system, comprising: an emergency treatment stage: establishing a logic interlocking between a pre-storage section pressure and a furnace top diffuser valve action, and before emergency treatment, namely when the pre-storage chamber pressure is greater than or equal to 100 Pa, the furnace top diffuser valve is automatically opened to ensure that the system pressure is not greater than 100 Pa; (1) a south area control strategy: executing an emergency shutdown sequence: 1) the coke charging system is automatically cut off, the delay is less than or equal to 5 s, 2) a circulating fan speed-down curve: non-linearly decreasing to 70% in the first 30 seconds and then decreasing to 50% in the next 60 seconds, 3) air introduction valve dynamic balance control: PID regulation based on pressure feedback, the regulation period is less than or equal to 3 s, 4) gradual adjustment: the opening degree of the 1# and 2# desulfurization system inlet valves is dynamically adjusted to 20%, and in this process, the pre-storage chamber pressure parameter needs to be continuously monitored to ensure that it is maintained within the control range of 0-100 Pa; (2) a north area control strategy: executing a double system, namely air introduction valve regulation system and desulfurization valve regulation system, to realize coordinated regulation: 1) the air introduction valve and the desulfurization valve are coupled to control, and the opening degree ratio is maintained at 1:1.2, 2) the circulating fan keeps inertial operation, and the speed attenuation rate is less than or equal to 2% per minute, 3) a pressure buffer model is established: the pre-storage chamber pressure prediction value = the measured value + 0.3*(dP / dt), the unit of the pre-storage chamber pressure prediction value is Pa, the unit of the measured value is Pa, dP is the pressure, the unit is Pa, and dt is the time, the unit is second; a system recovery stage: (1) fan soft start control: 1) an S-shaped acceleration curve is adopted, and the acceleration is less than or equal to 1.5% per second in the 10%-30% speed interval, 2) the dynamic matching circulating fan and desulfurization fan speed difference is maintained to be less than or equal to 15%, (2) parameter recovery optimization control: 1) a three-dimensional parameter regression model is established: f(speed, opening degree, pressure) = alpha*n^2 + beta*theta + gamma*P, n^2 is the speed, the unit is rad / min, theta is the desulfurization valve opening degree, the unit is %, P is the pre-storage chamber pressure, the unit is Pa, a phased verification mechanism is implemented, the pressure stability detection is executed every 5% speed increase, and the pressure is within-100-0 Pa, 3) a secondary loop: desulfurization valve front pressure feedforward compensation, the compensation amount is 0.7*Delta P, the unit of the compensation amount is Pa, and Delta P is the pressure, the unit is Pa.

[0009] The beneficial effects of the present application are: 1. the fault response time is shortened to within 45 seconds; 2. the pressure control precision is improved to ± 50 Pa; 3. the system recovery time is compressed to 35 minutes; 4. the energy consumption is reduced by 12-15%; 5. regional differentiation precise regulation is realized; and 6. the system operation reliability is improved. DETAILED DESCRIPTION

[0010] The innovation points of the present application mainly lie in the following aspects: 1. an abnormality determination method of multi-parameter linkage: through the comprehensive judgment of pressure change gradient, current fluctuation and interlocking signal, the rapid and accurate identification of faults is realized.

[0011] 2. Regional differentiated emergency disposal strategy: According to the process characteristics of north and south areas, the corresponding control strategy is formulated.

[0012] 3. Stage soft start control: S-shaped acceleration curve and dynamic speed matching are adopted to ensure the stable start of the system.

[0013] 4. Three-dimensional parameter regression model: The nonlinear relationship between speed, opening and pressure is established to realize the optimization recovery of parameters.

[0014] 5. Pressure buffer model: Through pressure prediction and dynamic adjustment, the system pressure is maintained stable.

[0015] 6. Multi-loop coordinated control method: The coordinated control of main loop and auxiliary loop is realized, and the overall performance of the system is improved.

[0016] The implementation of the present application can significantly improve the operation reliability of the dry quenching flue gas desulfurization system, reduce the fault response time and system recovery time, and at the same time realize the saving of energy and the improvement of operation efficiency.

[0017] The present application provides a multi-parameter linkage desulfurization system fault disposal method, comprising the following steps: 1. Abnormality determination stage: 1.1 DCS system real-time monitoring pre-storage chamber pressure change gradient, when ΔP / Δt≥50Pa / s, triggering first level alarm.

[0018] 1.2 After the first level alarm is triggered, the desulfurization fan current fluctuation is detected synchronously, and the current sudden drop ≥30% triggers the second level alarm, which needs the confirmation of the desulfurization fan running state by the main control and the field personnel.

[0019] 1.3 Interlock shutdown signal verification (firing system and fan running state logic interlocking), that is, the desulfurization fan abnormally stops, triggering the third level alarm, corresponding to the locking of the charging device of the dry quenching furnace.

[0020] 2. Emergency disposal stage: Establish the logic interlocking of pre-storage section pressure and furnace top blow-off valve action, and use it before emergency disposal, that is, when the pre-storage chamber pressure ≥100Pa, the furnace top blow-off valve is automatically opened to ensure that the system pressure does not exceed the standard.

[0021] South zone control strategy: 2.1 execute emergency shutdown sequence: 2.1.1 automatic cut-off of the coke charging system (delay ≤ 5 s). 2.1.2 circulating fan speed-down curve: non-linear decrease (speed down to 70% in the first 30 seconds and to 50% in the last 60 seconds). 2.1.3 dynamic balance control of air inlet valve: PID adjustment based on pressure feedback (adjustment period ≤ 3 s). PID control is the most widely used and mature control strategy in the field of industrial control. It is named after its three core components: proportional (P), integral (I), and derivative (D). A PID controller calculates an error signal (the difference between the desired value / setpoint and the actual measured value) in real time and performs operations based on the proportional, integral, and derivative of the error. Finally, it outputs a control signal to drive the actuator, making the actual output of the controlled system reach the desired value as quickly, smoothly, and accurately as possible. 2.1.4 gradually adjust the opening of the 1# and 2# desulfurization system inlet valves, dynamically adjusting the opening value to 20%. During this process, the pre-storage chamber pressure parameter needs to be continuously monitored to ensure that it remains within the control range of 0-100 Pa.

[0022] North zone control strategy: 2.2 execute dual-system coordinated regulation: 2.2.1 coupled control of air inlet valve and desulfurization valve (opening ratio maintained at 1:1.2). 2.2.2 circulating fan maintains inertial operation (speed decay rate ≤ 2% / min). 2.2.3 establish a pressure buffer model: pre-storage chamber pressure prediction value = measured value + 0.3 × (dP / dt).

[0023] 3. System recovery phase: 3.1 fan soft start control: 3.1.1 use S-shaped acceleration curve (acceleration ≤ 1.5% / s in the 10%-30% speed range). 3.1.2 dynamically match the speed difference between the circulating fan and the desulfurization fan (maintain ≤ 15%) which is the speed of the circulating fan minus the speed of the desulfurization fan, divided by the speed of the circulating fan, and the final calculation result ≤ 0.15.

[0024] 3.2 parameter recovery optimization control: 3.2.1 establish a three-dimensional parameter regression model: f(speed, opening, pressure) = α*n² + β*θ + γ*P. 3.2.2 implement a phased verification mechanism (perform pressure stability detection every 5% speed increase). 3.2.3 secondary loop: desulfurization valve pre-pressure feedforward compensation (compensation amount = 0.7 × ΔP). Example 1 (South zone)

[0025] Step 1: When the DCS system detects that the pre-storage chamber pressure ≥ +80 Pa and lasts for 10 seconds, trigger the three-level interlock: emergency shutdown of the coke charging system; desulfurization fan executes soft shutdown; circulating fan enters speed-down mode.

[0026] Step 2: Perform pressure gradient control equation: when ΔP / Δt≥30 Pa / s: air introduction valve closing rate = basic rate × (1+0.05×ΔP); ΔP unit is Pa, Δt unit is second Desulfurization gate opening correction coefficient = 1 / (1+0.02×t) (t is the shutdown time, unit is second). Example 2 (North Zone)

[0027] Step 1: Establish a dual-loop pressure compensation system: main loop: pre-storage chamber pressure PID control (Kp=2.5, Ki=0.05, Kd=0.8); secondary loop: desulfurization valve front pressure feedforward compensation (compensation amount = 0.7×ΔP), ΔP unit is Pa.

[0028] Step 2: Implement multi-objective optimization control: minΣ(pressure deviation²+valve action amount²); s.t. fan speed ≤ safety threshold; equipment parameter change rate ≤ maximum allowed value.

[0029] The above only describes specific embodiments of the present application, but the structural features of the scope of protection of the present application are not limited to this, any person skilled in the art in the field of the present application, the changes or modifications made are covered by the patent scope of the present application.

Claims

1. A method for determining abnormality in a CDQ FGD system, characterized by: The following steps are involved: Step 1: The DCS system monitors the pressure gradient of the pre-storage chamber in real time. When ΔP / Δt, i.e., the pressure change rate, is ≥50 Pa / s, a level 1 alarm is triggered. ΔP is the pressure value in Pa, and Δt is the time in seconds. Step 2: After the first-level alarm is triggered, the current fluctuation of the desulfurization fan is detected simultaneously. If the current drops by ≥30%, the second-level alarm is triggered, and the main control personnel and on-site personnel are required to confirm the operating status of the desulfurization fan; Step 3: Interlock shutdown signal verification means that the desulfurization fan stops abnormally, triggering the third-level alarm and locking the corresponding CDQ furnace loading device.

2. A method for handling abnormalities in a CDQ flue gas desulfurization system, characterized by: include: Emergency response phase: establish a logical interlock between the pre-storage section pressure and the furnace top relief valve action, and put it into use before emergency response, that is, when the pre-storage chamber pressure ≥100Pa, the furnace top relief valve automatically opens to ensure that the system pressure does not exceed the standard, that is, not ≥100Pa; (1) South zone control strategy: execute the emergency shutdown sequence: 1) the coke loading system is automatically cut off, with a delay of ≤5s, 2) the circulating fan speed reduction curve: the speed is reduced to 70% in the first 30 seconds of nonlinear decrease, and to 50% in the next 60 seconds, 3) dynamic balance control of the air inlet valve: PID adjustment based on pressure feedback, with an adjustment period of ≤3s, 4) step-by-step adjustment: the opening of the inlet valve of the 1# and 2# desulfurization systems, the opening value is dynamically adjusted To 20%. During this process, the pre-storage chamber pressure parameters need to be continuously monitored to ensure that they are maintained within the control range of 0-100Pa; (2) North zone control strategy: implement dual system, namely the air introduction valve regulation system and the desulfurization valve regulation system for coordinated regulation: 1) The air introduction valve and the desulfurization valve are coupled and controlled, and the opening ratio is maintained at 1:1.2; 2) The circulating fan maintains inertial operation, and the speed attenuation rate is ≤2% / min; 3) Establish a pressure buffer model: the pre-storage chamber pressure prediction value = the measured value + 0.3×(dP / dt), the pre-storage chamber pressure prediction value unit is Pa, the measured value unit is Pa, dP is pressure, unit is Pa, dt is time, unit is second; System recovery phase: (1) Fan soft start control: 1) Adopt S-type acceleration curve, 10%-30% speed range acceleration ≤1.5% / s, 2) Dynamically match the speed difference between the circulation fan and the desulfurization fan to keep the speed difference between the circulation fan and the desulfurization fan ≤15%, (2) Parameter recovery optimization control: 1) Establish a three-dimensional parameter regression model: f(speed, opening, pressure) = α*n²+β*θ+γ*P, n² is the speed, the unit is rad / min, θ is the desulfurization valve opening, the unit is %, and P is the pre-storage chamber pressure, the unit is Pa. Implement a phased verification mechanism, perform pressure stability detection every 5% speed increase, the pressure is between -100~0Pa, 3) Auxiliary loop: Desulfurization valve front pressure feedforward compensation, compensation amount = 0.7×ΔP, compensation amount unit is Pa, ΔP is pressure, the unit is Pa.