Auxiliary control method for sulfuric acid plant

Abstract

An auxiliary control method for a sulfuric acid plant comprises tail gas emptying SO2 automatic control and tail gas emptying SO2 automatic control, specifically, during back flushing of a tail washing online monitoring device, the descent rate in a PVI module is decreased, an alarm module starts to give an alarm, and at the moment, a PV value of PID is switched from a tail emission SO2 content measured value to a set value so as to stabilize the frequency of a hydrogen peroxide pump; the invention relates to the field of chemical equipment, in particular to an auxiliary control method for a sulfuric acid plant. The method has the beneficial effects that 1, a device control loop is set and optimized by using a standard control loop setting method;

Description

Technical Field

[0001] The invention relates to the field of chemical equipment, and in particular to an auxiliary control method for a sulfuric acid plant. Background Art

[0002] In the field of process industry, many chemical companies are actively using various cutting-edge technologies to strive to achieve operational excellence and thus consolidate their position in the fierce market competition. However, although these efforts are worthy of recognition, many chemical companies often ignore the potential opportunities in certain key areas in their pursuit of excellence. Especially at the basic control level, such as the precise setting of PID parameters and the deep optimization of control schemes, these seemingly subtle links actually contain huge room for improvement. Therefore, if chemical companies can dig deeper into these areas, they are expected to further improve operational efficiency and win more lasting market competitiveness for the company.

[0003] PID control plays an important role in industrial process automatic control systems due to its simple structure, strong robustness and easy mastery by operators. More than 90% of controllers use PID control strategy. However, despite the wide application of PID control, studies have shown that up to 80% of controllers in actual industries have performance problems, which greatly affects the control effect and economic operation efficiency of industrial processes. Summary of the invention

[0004] The purpose of the present invention is to provide an auxiliary control method for a sulfuric acid plant in view of the above-mentioned shortcomings.

[0005] The present invention provides the following technical solutions: The beneficial effects of the present invention are: 1. The control loop of the device is calibrated and optimized using a standard control loop calibration method.

[0006] 2. Operation event statistics can reduce the number of manual interventions in all control loops by more than 80%.

[0007] 3. Through server installation and deployment, data collection, software installation and configuration, analyze operation events, process indicators, system alarms, etc., to provide theoretical support for continuous improvement.

[0008] 4. Effectively tap the potential of the existing DCS control system, analyze operational events, adjust and optimize control loop parameters, use advanced software to reduce the difficulty of control loop maintenance, improve the factory's production management level and intelligence, effectively reduce labor intensity, improve system safety and stability, and reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of the control circuit for automatic control of exhaust SO2; Figure 2 Schematic diagram of the control circuit for exhaust SO2 automatic control; Figure 3 This is a schematic diagram of the control circuit for automatic switching control of steam condensation and hot water; Figure 4 It is a schematic diagram of the control circuit for the automatic switching control of steam condensation and hot water; Figure 5 This is a schematic diagram of the automatic control circuit for the liquid level of the concentrated acid circulation tank; Figure 6 This is a schematic diagram of the control circuit for the automatic control of the liquid level in the concentrated acid circulation tank; Figure 7 This is a schematic diagram of the automatic control circuit for acid concentration regulation; DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0011] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0012] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0013] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the invention is usually placed when in use. This is only for the convenience of describing the present invention 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 present invention. In addition, if the terms "first", "second", etc. appear in the description of the present invention, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0014] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting" and "connection" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0015] The present invention (1) automatically controls the exhaust of SO2 from tail gas.

[0016] a. Control strategy: This loop is a single-loop control, in which the backwash of the tail wash online monitoring device will affect the stability of the loop. Its characteristic is that the measured value of the tail exhaust SO2 content drops sharply in a distorted state in a short period of time, affecting the frequency adjustment of the hydrogen peroxide pump. Using this feature, the descent rate alarm in the PVI module is used to stabilize the frequency of the hydrogen peroxide pump. During backwashing, the descent rate alarm is also triggered, and the PV value of the PID is switched from the tail exhaust SO2 content measurement value to the set value to stabilize the frequency of the hydrogen peroxide pump, ensuring that the tail exhaust SO2 content does not exceed the standard after backwashing.

[0017] b. Control procedures: such as Figure 1 , 2 As shown, C. Detailed control process: AT_145401FB is a rate detection module. When the tail discharge value drops by 15mg / m³ in 1 second, the module generates a negative rate alarm. At this time, the DED pure hysteresis (3 seconds) module outputs the tail discharge set value, and the time is 110 seconds. When no backflush is detected, the DED module outputs the tail discharge true value. The pure hysteresis of 3 seconds is to make the transition process smoother. The output value of the DED module is filtered for 3 seconds and then sent to the PV value of the PID for PID control.

[0018] , (2) Automatic control of active power generation and power factor

[0019] General control strategy: When adjusting active power and power factor, the DCS sends pulse signals to 505 for control. The PULPOS function block is used to generate pulse signals according to the deviation between the calculated value (active power / power factor) and the actual value (active power / power factor) to achieve the control effect.

[0020] a. Control strategy: N75 active power: Control the network pressure through the N75 power generation. When the network pressure deviates from the pressure setting value, the N75 generator automatically adjusts the power generation load to achieve the effect of stable control of the network pressure.

[0021] c. Detailed control process: The PV value of the PID module is the low-pressure steam network pressure, and the MV value is the generated power. The power is sent to the set value of the pulse module FDCS. The measured value of FDCS is the current power of the N75 generator. After comparing it with the set value, a pulse signal for increasing or decreasing the speed is generated.

[0022] a.Control strategy: CB6 active: Control the main steam valve steam inlet pressure through CB6 power generation. When the steam inlet pressure deviates from the pressure setting value, the CB6 generator automatically adjusts the power generation load to achieve the effect of stable control of the steam inlet pressure.

[0023] c. Detailed control process: The PV value of the PID module is the value of the steam pressure in front of the CB6 main steam valve after 20 seconds of filtering. The MV value is the generated power. The power is given to the set value of the pulse module. The pulse module measures the current power of the generator. After comparing it with the set value, it generates a pulse signal to increase or decrease the speed.

[0024] a. Control strategy: C12 active power: Manually input the power value to control the active power.

[0025] c. Detailed control process: The PV value of the handheld operator module is the current power of the generator. The power value entered by the operator is given to the set value of the pulse module. The pulse module measures the signal of the current power of the generator filtered for 20 seconds, and after comparing it with the set value, it generates a pulse signal for increasing or decreasing the speed.

[0026] a. Control strategy: N75 power factor: The current control strategy is to generate a broken line based on the power factor corresponding to the active power, and control the power factor to automatically add or subtract reactive power. c. Detailed control process: According to the N75 active power and the operator's experience, the power factor corresponding to the current power generation is obtained through the line graph and given to the handheld operator module IN. When the handheld operator is put into automatic operation, the handheld operator gives the power factor to the pulse module setting value. The pulse module measurement value is a signal filtered for 20 seconds for the current power factor of the generator. After comparing it with the setting value, a pulse signal of adding or subtracting reactive power is generated. When the handheld operator is switched to manual mode, the operator can input the power factor in the handheld operator.

[0027] a. Control strategy: CB6 power factor: Automatically control the power factor setting value according to a section of bus voltage to automatically increase or decrease reactive power c. Detailed control process: The PV value of the PIDEX module is the 5-second value of a bus voltage filter, and the MV value is the power factor. The power factor is sent to the set value of the pulse module. The pulse module measurement value is the filtered value of the current power factor of the generator. After comparing it with the set value, it generates a pulse signal of adding or subtracting reactive power.

[0028] a. Control strategy: C12 power factor: Automatically control the power factor setting value based on the two-stage bus voltage to automatically increase or decrease reactive power c. Detailed control process: The PV value of the PID module is the value after the second-stage bus voltage is filtered for 5 seconds, and the MV value is the power factor. The power factor is sent to the set value of the pulse module. The measured value is the value of the current power factor of the generator after filtering for 20 seconds. After comparing with the set value, a pulse signal of adding or subtracting reactive power is generated.

[0029] The calculation formulas involved in the active power and power factor of power generation are: This function block outputs positive pulse and reverse pulse in each pulse cycle TCYC according to the comparison result of deviation and dead zone DB.

[0030] If the deviation EI is within the dead zone [-DB, DB], there is no pulse output signal.

[0031] If EI>DB, a positive pulse is generated.

[0032] .

[0033] (3) Automatic switching control of steam condensation and hot water.

[0034] a. Control strategy: Use the frequency of the soft water pump to control the flow of soft water entering the second-line deaerator, and the cascade control of the liquid level of the first-line deaerator. The inverted soft water tank causes the inlet pressure of the soft water pump to change, causing the flow fluctuation of the deaerator and the interlocking reaction of the deaerator liquid level fluctuation. Putting the flow into the cascade can eliminate the influence, but the flow of the first-line deaerator is not accurate, so consider using the soft water flow of the second-line deaerator with the same frequency fluctuation. The liquid level of the first-line deaerator is controlled by the flow of the soft water pump of the desalted water, and the liquid level of the soft water tank is controlled by the second-line soft water flow of the soft water pump of the desalted water. Prevent the failure of this circuit when the second line is stopped.

[0035] b. Control procedures: such as Figure 3 , 4 As shown, c. Detailed control process: The outer loop of the cascade is the deaerator level control. The deaerator level is the PV value. The MV value is used as the set value of the inner loop hot water pump frequency modulation control. The inner loop PV value is the soft water flow to the second-line deaerator, and the MV output controls the pump frequency. The advantage of the cascade is that the interference caused by flow fluctuations can be quickly adjusted through the inner loop.

[0036] Flow control in cascade is a self-balancing object: , The following formula can be used to determine the PID tuning parameters of the self-balancing object:

[0037]

[0038] (2) Controller gain Kc Kc: Controller gain, one of the controller parameters.

[0039] T: time constant, usually in seconds (s).

[0040] K: Self-balancing object gain as described above.

[0041] λ: The time constant of the object.

[0042] τ: lag time.

[0043] (3). Proportional band PB PB: Proportional band, a parameter of the controller, used to set the proportional coefficient of the controller output change.

[0044] Kc: controller gain.

[0045] (4). Integration time TI TI=T TI represents the integration time.

[0046] (5). Differential time D D=0 The derivative time D is set to 0, which means that the controller has no derivative action.

[0047] (4) Automatic control of boiler feed water level.

[0048] a. Control strategy: The boiler feed water flow rate is the total flow rate at the boiler feed water pump outlet minus the two-stage water spray cooling water flow rate. The drum liquid level and the drum feed water flow rate are controlled in cascade. The drum liquid level controls the flow rate, and the flow rate controls the water spray cooling valve, ensuring that the drum liquid level is not affected by flow changes when the water spray cooling valve grabs water.

[0049] c. Detailed control process: The outer loop of the cascade is the boiler level control. The boiler level is the PV value. The MV value is the set value of the inner loop flow control. The inner loop PV value is the total flow at the boiler feed pump outlet minus the two-stage spray cooling water flow, which is the boiler feed flow. MV controls the opening of the feed valve. The advantage of the cascade is that it can suppress the fluctuation of the inner loop caused by flow changes as soon as possible. The flow is a self-balancing object and the liquid level is an integral object. The calculation is as follows:

[0050] (1) Integral object gain K K: Gain of the integration object.

[0051] k2−k1: The difference in the controlled variable PV at different time points.

[0052] PV range: PV range.

[0053] ΔOP: The change in controller output.

[0054] OP range: the range of controller output.

[0055] Here k2−k1 represents the difference between the final stable slope of PV after the controller output changes and the initial slope.

[0056] (2) Controller gain Kc Kc: controller gain.

[0057] K: Gain of the integration object.

[0058] λ: The time constant of the object.

[0059] τ: lag time.

[0060] (3) Proportional band PB PB: Proportional band, a parameter of the controller, used to set the proportional coefficient of the controller output change.

[0061] Kc: controller gain.

[0062] (4) Integration time TI TI=4(λ+τ) TI: Integral time, usually associated with the integral action of the controller, that is, the ability of the controller to eliminate steady-state errors.

[0063] λ: The time constant of the object.

[0064] τ: lag time.

[0065] (5). Differential time D D=0 The derivative time D is set to 0, which means that the controller has no derivative action.

[0066] (5) Automatic control of liquid level in concentrated acid circulation tank.

[0067] a. Control strategy: The acid-generating valve controls the average liquid level of the drying and second-suction circulation tanks through PID; the second-suction valve in the drying series controls the liquid level difference of the drying and second-suction circulation tanks through PID and always keeps it at 0m. to play the role of a balancing pipe. The two control the liquid levels of the two circulation tanks together to ensure the liquid level balance of the two tanks.

[0068] b. Control procedures: such as Figure 5 , 6 As shown, c. Detailed control process: Calculate the average of the drying and di-acid absorption levels as the PV value of the level control PID.

[0069] Calculate the difference between the dry acid and di-absorbent acid levels as the PV value of the level control PID.

[0070] This control loop is an integral object, and the calculation formula is:

[0071] 1. Integral object gain K K: Gain of the integration object.

[0072] k2−k1: The difference in the controlled variable PV at different time points.

[0073] PV range: PV range.

[0074] ΔOP: The change in controller output.

[0075] OP range: the range of controller output.

[0076] Here k2−k1 represents the difference between the final stable slope of PV after the controller output changes and the initial slope.

[0077] 2. Controller gain Kc Kc: controller gain.

[0078] K: Gain of the integration object.

[0079] λ: The time constant of the object.

[0080] τ: lag time.

[0081] 3. Proportional band PB PB: Proportional band, a parameter of the controller, used to set the proportional coefficient of the controller output change.

[0082] Kc: controller gain.

[0083] 4. Integration time TI TI=4(λ+τ) TI: Integral time, usually associated with the integral action of the controller, that is, the ability of the controller to eliminate steady-state errors.

[0084] λ: The time constant of the object.

[0085] τ: lag time.

[0086] For an integral object, the selection of the integral time usually takes into account the time constant and lag time of the object to ensure that the system has good dynamic response performance.

[0087] 5. Differential time D D=0 The derivative time D is set to 0, which means that the controller has no derivative action.

[0088] (6) Automatic control of acid concentration adjustment.

[0089] a. Control strategy: This control loop is a single loop. The valve opening is automatically controlled according to the deviation between the acid concentration and the set value to adjust the amount of desalted water / dilute acid added to the circulation tank to control the acid concentration stability. When the safety interlock is activated, the valve is automatically closed.

[0090] b. Control procedures: such as Figure 7 As shown, c. Detailed control process: The PV value of the PID module is the acid concentration of the disulfide. After comparing it with the set value, the water adding valve opening is adjusted. SWTR is the interlocking signal. After the action, the TV value (0) is output as the valve opening, that is, the valve is closed after the interlocking action.

[0091] This control loop is an integral object, and the calculation formula is:

[0092] 1. Integral object gain K K: Gain of the integration object.

[0093] k2−k1: The difference in the controlled variable PV at different time points.

[0094] PV range: The measuring range of PV.

[0095] ΔOP: The change in controller output.

[0096] OP range: The range of the controller output.

[0097] Here k2−k1 represents the difference between the final stable slope of PV after the controller output changes and the initial slope.

[0098] 2. Controller gain Kc Kc: controller gain.

[0099] K: Gain of the integration object.

[0100] λ: The time constant of the object.

[0101] τ: lag time.

[0102] 3. Proportional band PB PB: Proportional band, a parameter of the controller, used to set the proportional coefficient of the controller output change.

[0103] Kc: controller gain.

[0104] 4. Integration time TI TI=4(λ+τ) TI: Integral time, usually associated with the integral action of the controller, that is, the ability of the controller to eliminate steady-state errors.

[0105] λ: The time constant of the object.

[0106] τ: lag time.

[0107] For an integral object, the selection of the integral time usually takes into account the time constant and lag time of the object to ensure that the system has good dynamic response performance.

[0108] 5. Derivative time D D=0 The derivative time D is set to 0, which means that the controller has no derivative action.

[0109] 4. Operation and alarm analysis: Regularly download and sort the operation and alarm records of the device, solve the top few items with frequent operations and alarms, analyze, formulate solutions, and gradually reduce the frequency of operations and alarms. Identify problems in the operation process, determine the direction of control solution optimization, put forward suggestions for instrument equipment inspection and maintenance, change the control strategy for complex control, such as cascade and other methods, and strengthen the anti-interference ability and reduce system fluctuations through reasonable control strategies.

[0110] 5. Optimization of process parameters: With the improvement of the automatic control rate, the process indicators can be optimized according to the design. Under the premise of ensuring the production safety of the device, the material and energy consumption of the device can be reduced and the steam production rate of the device can be increased. At the same time, functions such as automatic generation of design reports can be designed to continuously improve the level of automation and reduce the labor intensity of employees.

[0111] 6. Personnel training: Instrumentation process personnel participate in the whole process of project implementation, master the standard control loop tuning method, so that they can reach the level of optimizing PID parameters independently and have the ability to optimize control loops.

[0112] (1) Carry out the work in stages, and the implementation team members should keep a work log to record the progress of the work.

[0113] (2) Actively participate in weekly and monthly meetings, report on the current work progress and the next stage of work goals in a timely manner, and summarize the shortcomings and improvement measures in the work.

[0114] (3) After the project team arrives, they will organize on-site observation and learning. On the one hand, they will assist them in completing the preliminary work, and on the other hand, they will understand and learn the workflow of digital transformation and the operation and data collection of related platforms.

[0115] (4) Invite project team experts to provide guidance and explanations, using actual cases and difficult points in previous work to solve problems encountered in actual independent work. At the same time, based on the actual situation of the factory, explain the general operating procedures and methods in the form of simulation exercises to help everyone run the work independently.

[0116] (5) Under the supervision and guidance of professionals, independently complete the input of relevant data, platform operation and emergency response. While improving practical operation capabilities, discover problems in actual operation.

[0117] (6) Organize theoretical examinations and practical examinations separately, with questions set based on the actual situation of the factory and targeted examinations conducted around problems that occurred in the early stages. The practical examinations should focus on emergency response and be assessed on a job-by-job basis.

Claims

1. An auxiliary control method for a sulfuric acid plant, characterized in that It includes automatic control of exhaust SO2, Automatic control of exhaust SO2: When the tail wash online monitoring device is backwashed, the drop rate in the PVI module decreases, and the alarm module starts to alarm. At this time, the PV value of the PID is switched from the measured value of the tail exhaust SO2 content to the set value to stabilize the frequency of the hydrogen peroxide pump; The PV value calculation formula of PID is:

2. The auxiliary control method for a sulfuric acid plant according to claim 1, characterized in that: It also has automatic switching control for steam condensation and hot water: the flow rate of the soft water pump in series with desalted water controls the liquid level of the first-line deaerator, and the frequency of the soft water pump in series with desalted water controls the liquid level of the second-line soft water tank; Among them, the flow control in the cascade is a self-balancing object: , Use the following formula to determine the PID tuning parameters of the self-balancing object: ， ， (2) Controller gain Kc Kc: controller gain, one of the controller parameters; T: time constant, usually in seconds (s); K: self-balancing object gain as described above; λ: time constant of the object; τ: lag time; (3). Proportional band PB PB: Proportional band, a parameter of the controller, used to set the proportional coefficient of the controller output change; Kc: controller gain; (4). Integration time TI TI=T TI represents the integration time; (5). Differential time D D=0 The derivative time D is set to 0, which means that the controller has no derivative action.

3. The auxiliary control method for a sulfuric acid plant according to claim 1, characterized in that: It also has automatic control of boiler feed water level: the drum level and drum feed water flow are controlled in cascade, the drum level controls the flow, and the flow controls the spray water cooling valve; the flow is the self-balancing object, the liquid level is the integral object, and the control formula is as follows: ， As mentioned above; ， (1) Integral object gain K K: Gain of the integral object; k2−k1: the difference in the controlled variable PV at different time points; PV range: PV range; ΔOP: the change in controller output; OP range: the range of the controller output; Here k2−k1 represents the difference between the final stable slope of PV after the controller output changes and the initial slope; (2) Controller gain Kc Kc: controller gain; K: Gain of the integral object; λ: time constant of the object; τ: lag time; (3) Proportional band PB PB: Proportional band, a parameter of the controller, used to set the proportional coefficient of the controller output change; Kc: controller gain; (4) Integration time TI TI=4(λ+τ) TI: Integral time, usually associated with the integral action of the controller, that is, the ability of the controller to eliminate steady-state errors; λ: time constant of the object; τ: lag time; (5). Differential time D D=0 The derivative time D is set to 0, which means that the controller has no derivative action.

4. The auxiliary control method for a sulfuric acid plant according to claim 1, characterized in that: It also has automatic control of the concentrated acid circulation tank level: the acid-generating valve controls the average level of the drying and secondary suction circulation tanks through PID; Calculate the average of the drying and di-acid absorption levels as the PV value of the level control PID. Calculate the difference between the dry acid and di-absorbed acid levels as the PV value of the level control PID. This control loop is an integral object, and the calculation formula is: ， (1) Integral object gain K K: Gain of the integral object; k2−k1: the difference in the controlled variable PV at different time points; PV range: PV range; ΔOP: the change in controller output; OP range: the range of the controller output; Here k2−k1 represents the difference between the final stable slope of PV after the controller output changes and the initial slope; (2) Controller gain Kc Kc: controller gain; K: Gain of the integral object; λ: time constant of the object; τ: lag time; (3) Proportional band PB PB: Proportional band, a parameter of the controller, used to set the proportional coefficient of the controller output change; Kc: controller gain; (4) Integration time TI TI=4(λ+τ) TI: Integral time, usually associated with the integral action of the controller, that is, the ability of the controller to eliminate steady-state errors; λ: time constant of the object; τ: lag time; For integral objects, the selection of integral time usually takes into account the object's time constant and lag time to ensure that the system has good dynamic response performance; (5). Differential time D D=0 The derivative time D is set to 0, which means that the controller has no derivative action.

5. The auxiliary control method for a sulfuric acid plant according to claim 1, characterized in that: It also has automatic control for acid concentration adjustment: this control loop is a single loop, and the valve opening is automatically controlled according to the deviation between the acid concentration and the set value to adjust the amount of desalted water / dilute acid added to the circulation tank to control the acid concentration stability. When the safety interlock is activated, the valve is automatically closed; This control loop is an integral object, and the calculation formula is: ， (1) Integral object gain K K: Gain of the integration object, k2−k1: The difference in the controlled variable PV at different time points, PV range: PV range, ΔOP: the change in controller output, OP range: the range of the controller output, Here k2−k1 represents the difference between the final stable slope of PV and the initial slope after the controller output changes. (2) Controller gain Kc Kc: controller gain, K: Gain of the integration object, λ: the time constant of the object, τ: lag time, (3) Proportional band PB PB: Proportional band, a parameter of the controller, used to set the proportional coefficient of the controller output change. Kc: controller gain, (4) Integration time TI TI=4(λ+τ) TI: Integral time, usually associated with the integral action of the controller, that is, the ability of the controller to eliminate steady-state errors, λ: the time constant of the object, τ: lag time, For integral objects, the selection of integral time usually takes into account the time constant and lag time of the object to ensure that the system has good dynamic response performance. (5). Differential time D D=0 The derivative time D is set to 0, which means that the controller has no derivative action.

6. The auxiliary control method for a sulfuric acid plant according to claim 1, characterized in that: It also has automatic control of active power generation and power factor: when adjusting active power and power factor, pulse signals are sent to 505 through DCS to control, and the PULPOS function block is used to generate pulse signals according to the deviation between the calculated value and the actual value to achieve the control effect.

7. The auxiliary control method for a sulfuric acid plant according to claim 6, characterized in that: Power generation control method: The network pressure is controlled by generating power. When the network pressure deviates from the set pressure value, the generator automatically adjusts the generating load to achieve the effect of stabilizing the network pressure. Among them, the PV value of the PID module is the low-pressure steam network pressure, the MV value is the generated power, the power is sent to the set value of the pulse module FDCS, and the measured value of FDCS is the current power of the generator. After comparing with the set value, a pulse signal for increasing or decreasing the speed is generated.

8. The auxiliary control method for a sulfuric acid plant according to claim 6, characterized in that: Power generation control method: The main steam valve inlet pressure is controlled by the power generation. When the inlet pressure deviates from the pressure setting value, the generator automatically adjusts the power generation load to achieve the effect of stable control of the inlet pressure. Among them, the PV value of the PID module is the value of the steam pressure in front of the main steam valve after 20 seconds of filtering, the MV value is the generated power, the power is given to the set value of the pulse module, and the pulse module measures the current power of the generator. After comparing it with the set value, it generates a pulse signal to increase or decrease the speed.

9. The auxiliary control method for a sulfuric acid plant according to claim 6, characterized in that: Manually input power value to control active power; Among them, the PV value of the handheld operator module is the current power of the generator. The power value entered by the operator is given to the set value of the pulse module. The pulse module measurement value is the signal of the current power of the generator filtered for 20 seconds. After comparing with the set value, a pulse signal for increasing or decreasing the speed is generated.

10. The auxiliary control method for a sulfuric acid plant according to claim 6, characterized in that: Power factor, automatically controls the power factor setting value according to a section of bus voltage to automatically increase or decrease reactive power: Among them, the PV value of the PIDEX module is the 5-second value of a bus voltage filter, the MV value is the power factor, the power factor is sent to the set value of the pulse module, and the pulse module measurement value is the current power factor filtered value of the generator. After comparing with the set value, a pulse signal of adding or subtracting reactive power is generated.

11. An auxiliary control method for a sulfuric acid plant according to claim 6 or 10, characterized in that: Automatically control the power factor setting value according to the two-stage bus voltage to automatically increase or decrease reactive power; Among them, the PV value of the PID module is the value after the second-stage bus voltage is filtered for 5 seconds, and the MV value is the power factor. The power factor is sent to the set value of the pulse module. The measured value is the value of the current power factor of the generator after filtering for 20 seconds. After comparing with the set value, a pulse signal of adding or subtracting reactive power is generated; The calculation formulas involved in the active power and power factor of power generation are: This function block outputs positive pulse and reverse pulse in each pulse cycle TCYC according to the comparison result of deviation and dead zone DB; If the deviation EI is within the dead zone [-DB, DB], there is no pulse output signal; If EI>DB, a positive pulse is generated; ， PV: Measured value SV: Set value EI: Deviation between measured value and set value FSR: Forward Travel Rate RSR: Reverse travel rate.

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