Fluidized bed boiler control system and bed pressure self-adaptive accurate control method

Abstract

According to the fluidized bed boiler control system and the bed pressure self-adaption accurate control method, the control system adjusts the frequency of a flue gas induced draft fan to achieve the stability of the hearth pressure of the fluidized bed boiler, and under the condition that a return feeder is adjusted, the bed pressure self-adaption accurate control method is achieved by controlling the air supply amount of a primary air fan of a combustor at the bottom of the fluidized bed boiler and the fuel amount of a fuel system. And a fuzzy control system deslagging distributor is used for adjusting the operation frequency to carry out deslagging control, so that the bed pressure of the control system can be controlled more quickly, stably and accurately.

Description

Technical Field

[0001] This invention relates to a fluidized bed boiler control system and a bed pressure adaptive precision control method, belonging to the field of fluidized bed boiler automatic control technology. Background Technology

[0002] Fluidized bed boilers are important industrial reaction devices in coal chemical and petrochemical industries, widely used in processes such as waste pyrolysis, coal pyrolysis, plastic pyrolysis, and solid waste treatment. In these devices, the fluidized bed solid heat carrier forms a moving bed or fluidized bed within the furnace, serving as a heat source for direct contact heat exchange with the materials. Stable bed pressure is a key parameter for ensuring the safe, stable, and efficient operation of the system.

[0003] The main equipment in the pyrolysis gasification process includes a fluidized bed boiler, a pyrolysis unit, a return material unit, and a slag discharge unit.

[0004] After the solid heat carrier is heated by the fluidized bed boiler, the high-temperature flue gas carries the high-temperature heat carrier into the cyclone separator. The separated high-temperature solid heat carrier is sent to the pyrolysis unit. The heat carrier acts as a heat source to pyrolyze and gasify the material in the pyrolysis unit. After the reaction is completed and cooled, the heat carrier and pyrolysis residue are sent back to the fluidized bed boiler through the intermediate silo unit for reheating. The heat carrier is recycled again after being heated in the furnace. The combustible components in the pyrolysis residue are heated and burned in the furnace. Large particles of non-combustible pyrolysis residue can be discharged to the slag discharge unit through the slag discharge port of the heat carrier furnace.

[0005] Fluidized bed boilers are of the circulating fluidized bed type. Bed pressure control is primarily achieved by adjusting the ash discharge unit to stabilize the bed pressure. The bed thickness is generally proportional to the bed pressure. Bottom ash discharge is a common method for adjusting bed pressure drop. The task of the bed pressure control system is to maintain the bed thickness at an appropriate value by adjusting the ash discharge rate. When periodic ash discharge is used, the bed pressure values ​​for starting and stopping the bottom ash discharge device are set in the control system to keep the bed pressure within a certain range.

[0006] Excessive bed pressure may lead to abnormal fluidization of bed materials, uneven gas distribution, increased equipment resistance, increased energy consumption, and even the risk of equipment overpressure. Insufficient bed pressure may cause bed cavitation, interruption of solid heat carrier circulation, fluctuations in reaction temperature, and a decline in product quality. In severe cases, it may lead to reaction termination or equipment damage.

[0007] Currently, traditional bed pressure control mostly employs single-loop PID (proportional-integral-derivative) control, which detects and compares the bed pressure in the dilute and dense phase regions, and its output directly controls the frequency of the slag discharge distributor. However, this method has significant drawbacks: 1. Significant time lag: There is a significant time lag between the change in bed pressure and the action of the slag discharge and distribution device. Conventional PID control is difficult to adapt to, which can easily lead to system oscillation and poor control quality.

[0008] 2. Nonlinearity: The characteristics of the slag discharge feeder (such as valve jamming and material bridging) and the flow characteristics of the material are both nonlinear, and the PID controller with fixed parameters has poor control effect when the operating conditions change.

[0009] 3. Poor anti-interference ability: For interference such as fluctuations in feed rate and changes in material characteristics, single PID control has a slow response and long recovery time.

[0010] Therefore, there is an urgent need in this field for an advanced method that can overcome large hysteresis and nonlinearity to achieve rapid, stable and precise control of bed pressure. Summary of the Invention

[0011] The technical problem solved by this invention is to address the various shortcomings of traditional bed pressure control methods in the existing technology, and to propose a fluidized bed boiler control system and a bed pressure adaptive and precise control method.

[0012] The present invention solves the above-mentioned technical problem through the following technical solution: A fluidized bed boiler control system includes a flue gas induced draft fan, a cyclone separator, a controller, a fuzzy controller, a feeding unit, a pyrolysis unit, an intermediate silo unit, a return feeder, a primary blower, a fuel system, a burner, an ash discharge distributor, an ash discharge unit, and a fluidized bed boiler, wherein: The controller is connected to the flue gas induced draft fan, intermediate silo unit, return feeder, fluidized bed boiler, fuel system, and primary blower to transmit control commands. The fuzzy controller is connected to the fluidized bed boiler, slag discharge feeder, and return feeder, and performs fuzzy control based on the upper-level control commands issued by the controller. The flue gas induced draft fan is connected to the cyclone separator, the feeding unit is connected to the pyrolysis unit, the fluidized bed boiler is connected to the cyclone separator, the fluidized bed boiler is connected to the slag discharge feeder, the slag discharge feeder is connected to the slag discharge unit, the fluidized bed boiler is connected to the return feeder, the return feeder is connected to the intermediate silo unit, the cyclone separator is connected to the pyrolysis unit, and the pyrolysis unit is connected to the intermediate silo unit. All of these are used to realize the linkage action between the upper-level and lower-level components. The primary blower and fuel system are both connected to the burner of the fluidized bed boiler.

[0013] When the heat carrier in the fluidized bed boiler burns to generate hot flue gas, it carries the heat carrier into the cyclone separator. The hot flue gas is then sent out by the flue gas induced draft fan. The heat carrier enters the pyrolysis unit, and the feeding unit sends the material into the pyrolysis unit. After pyrolysis is completed, the heat carrier mixed with the pyrolysis residue enters the intermediate silo unit and is then transported back into the fluidized bed boiler through the return feeder. The combustible substances in the pyrolysis residue burn in the fluidized bed boiler, while the non-combustible substances remain in the bed layer of the fluidized bed boiler.

[0014] The fluidized bed boiler has a pressure measuring point P1 in the upper dense phase zone and a pressure measuring point P2 in the dilute phase zone installed in its external passageway, and a furnace temperature measuring point T is installed inside the furnace. x The signal access controller is used to receive control commands issued by the controller. The pressure measuring point P1 in the upper dense phase zone is used to characterize the amount of material entering the fluidized bed boiler. The stable control of the pressure measuring point P2 in the dilute phase zone of the fluidized bed boiler is achieved by adjusting the frequency of the flue gas induced draft fan. The pressure measuring point P2 in the dilute phase zone and the frequency of the flue gas induced draft fan constitute a single-loop PID control loop.

[0015] The material level measurement of the intermediate silo unit is based on the differential pressure ΔP within the silo. 料仓 The material level height, material bulk density, and gravitational acceleration are determined, and the optimal material level height is regulated by controlling the frequency of the return feeder. The amount of material F entering the fluidized bed boiler is proportional to the pressure value at the pressure measuring point P1 in the dense phase zone. Under the condition that the pressure value P2 in the dilute phase zone is stable, the amount of material F in the return feeder is related to the differential pressure ΔP of the bed.

[0016] The fluidization state inside the furnace of the fluidized bed boiler is adjusted according to the blower start-up frequency. When the furnace temperature T... x Each increase in T x+10℃ Then reduce the fuel supply R of the bottom burner. 燃 When the temperature inside the furnace is T x Return to the process temperature range; otherwise, if the furnace temperature T x Reduce, adjust fuel supply R according to temperature changes. 燃 Until the temperature inside the furnace reaches T x Return to the process temperature range.

[0017] The fluidized bed boiler bed pressure adaptive control method implemented according to the fluidized bed boiler control system includes: The pressure value P1_actual in the dense phase region is collected in real time by the bed pressure detection unit. Compare the actual bed pressure value P1_actual in the dense phase region with the pressure value P2_actual in the dilute phase region to calculate the bed differential pressure ΔP. A fuzzy PID control algorithm is adopted to dynamically adjust the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd of the PID controller according to the bed differential pressure ΔP. The output signal of the PID controller running the fuzzy PID control algorithm is dynamically adjusted, and the output signal is used as the basic control quantity u_base(t) for the frequency control of the slag discharge feeder. A feedforward compensation algorithm is introduced. By monitoring the feed flow rate F_in entering the bed in real time, the feedforward compensation amount u_ff(t) is calculated according to the preset feedforward compensation model. Based on the basic control quantity u_base(t) and the feedforward compensation quantity u_ff(t), the final control output u_final(t) is obtained; The final control output u_final(t) is output to the slag discharge feeder, and the discharge rate of the bed material is controlled by the frequency of the conditional slag discharge feeder to maintain the stability of the bed pressure.

[0018] The bed differential pressure ΔP = P2_actual – P1_actual; The final control output is u_final(t) = u_base(t) + u_ff(t).

[0019] The fuzzy PID control algorithm is as follows: The bed differential pressure ΔP is used as the input variable of the fuzzy controller; The bed differential pressure ΔP is fuzzified to convert precise data into fuzzy data. A fuzzy control rule base is established, and fuzzy values ​​of PID parameter corrections ΔKp, ΔKi, and ΔKd are calculated from the fuzzy control rule base based on the fuzzy inference algorithm. The fuzzy values ​​of the PID parameter corrections ΔKp, ΔKi, and ΔKd are defuzzified to obtain the accurate correction values; The precise correction value of the PID parameter correction is adjusted online, and the final correction value is used for fuzzy PID control.

[0020] In the fuzzy control rule base, direct values ​​are assigned to the correction values ​​of each PID parameter. The values ​​of each PID parameter correction value constitute a fuzzy subset. The method for online correction of PID parameters is as follows: Kp= Kp0 +ΔKp, Ki = Ki0 +ΔKi, Kd = Kd0 +ΔKd In the formula, Kp0, Ki0, and Kd0 are the initial parameters of the PID controller.

[0021] The feedforward compensation model is: u_ff(t) = K×F_in(t – t¹); In the formula, K is the feedforward coefficient and t¹ is the estimated lag time for the feed disturbance to be transmitted to the bed pressure detection point.

[0022] The advantages of this invention compared to the prior art are: (1) The fluidized bed boiler control system and bed pressure adaptive precision control method provided by the present invention achieves the stability of the fluidized bed boiler chamber pressure by adjusting the frequency of the flue gas induced draft fan through the control system. Under the condition of fine adjustment of the return feeder, by controlling the air supply of the primary air fan of the bottom burner of the fluidized bed boiler and the fuel quantity of the fuel system, as well as the intermittent start and stop of the slag discharge feeder and the adjustment of the operating frequency, the control system achieves the automatic and stable control of the bed differential pressure. (2) The present invention adopts fuzzy PID control, which can adjust the controller parameters in real time and nonlinearly according to the bed pressure deviation and its changing trend, effectively overcoming the nonlinearity and large lag problem of the system, improving the adaptability of the control, and having better adaptive capability; (3) The present invention introduces feedforward control based on feed flow rate, which can act on the discharge mechanism in advance before it has an actual impact on the bed pressure, significantly suppressing the impact of the main disturbance (feed fluctuation) on the bed pressure, reducing overshoot, accelerating the system recovery speed, and improving anti-interference performance; (4) This invention combines the intelligent adjustment of fuzzy PID with the predictive nature of feedforward control, making bed pressure control faster, more stable and more accurate, effectively avoiding the continuous oscillation phenomenon under conventional PID control, and providing a guarantee for the long-term stable operation of the device. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the fluidized bed boiler control system provided by the present invention. Detailed Implementation

[0024] A fluidized bed boiler control system and a method for adaptive and precise bed pressure control are disclosed. The control system adjusts the frequency of the flue gas induced draft fan to stabilize the furnace pressure of the fluidized bed boiler. With the return feeder adjusted, the system controls the air supply of the primary air fan of the bottom burner of the fluidized bed boiler and the fuel quantity of the fuel system. The ash discharge control is achieved by adjusting the operating frequency of the ash discharge distributor of the fuzzy control system. This allows the bed pressure of the control system to be controlled more quickly, smoothly and precisely.

[0025] The fluidized bed boiler control system includes a flue gas induced draft fan, cyclone separator, controller, fuzzy controller, feeding unit, pyrolysis unit, intermediate silo unit, return feeder, primary blower, fuel system, burner, ash discharge distributor, ash discharge unit, and fluidized bed boiler, wherein: The controller is connected to the flue gas induced draft fan, intermediate silo unit, return feeder, fluidized bed boiler, fuel system, and primary blower to transmit control commands. The fuzzy controller is connected to the fluidized bed boiler, slag discharge feeder, and return feeder, and performs fuzzy control based on the upper-level control commands issued by the controller. The flue gas induced draft fan is connected to the cyclone separator, the feeding unit is connected to the pyrolysis unit, the fluidized bed boiler is connected to the cyclone separator, the fluidized bed boiler is connected to the slag discharge feeder, the slag discharge feeder is connected to the slag discharge unit, the fluidized bed boiler is connected to the return feeder, the return feeder is connected to the intermediate silo unit, the cyclone separator is connected to the pyrolysis unit, and the pyrolysis unit is connected to the intermediate silo unit. All of these are used to realize the linkage action between the upper-level and lower-level components. The primary blower and fuel system are both connected to the burner of the fluidized bed boiler.

[0026] When the heat carrier in the fluidized bed boiler burns to generate hot flue gas, it carries the heat carrier into the cyclone separator. The hot flue gas is then sent out by the flue gas induced draft fan. The heat carrier enters the pyrolysis unit, and the feeding unit sends the material into the pyrolysis unit. After pyrolysis is completed, the heat carrier mixed with the pyrolysis residue enters the intermediate silo unit and is then transported back into the fluidized bed boiler through the return feeder. The combustible substances in the pyrolysis residue burn in the fluidized bed boiler, while the non-combustible substances remain in the bed layer of the fluidized bed boiler.

[0027] In the external passage of the chemical bed boiler, pressure measuring point P1 in the upper dense phase zone and pressure measuring point P2 in the dilute phase zone are installed, and furnace temperature measuring point T is installed inside the furnace. x The signal access controller is used to receive control commands issued by the controller. The pressure measuring point P1 in the upper dense phase zone is used to characterize the amount of material entering the fluidized bed boiler. The stable control of the pressure measuring point P2 in the dilute phase zone of the fluidized bed boiler is achieved by adjusting the frequency of the flue gas induced draft fan. The pressure measuring point P2 in the dilute phase zone and the frequency of the flue gas induced draft fan constitute a single-loop PID control loop.

[0028] The material level measurement in the intermediate silo unit is based on the differential pressure ΔP within the silo. 料仓 The material level height, material bulk density, and gravitational acceleration are determined, and the optimal material level height is regulated by controlling the frequency of the return feeder. The amount of material F entering the fluidized bed boiler is proportional to the pressure value at the pressure measuring point P1 in the dense phase zone. Under the condition that the pressure value P2 in the dilute phase zone is stable, the amount of material F in the return feeder is related to the differential pressure ΔP of the bed.

[0029] The fluidization state inside the furnace of a fluidized bed boiler is adjusted according to the blower start-up frequency. When the furnace temperature T... x Each increase in T x+10℃ Then reduce the fuel supply R of the bottom burner. 燃 When the temperature inside the furnace is T x Return to the process temperature range; otherwise, if the furnace temperature T x Reduce, adjust fuel supply R according to temperature changes. 燃Until the temperature inside the furnace reaches T x Return to the process temperature range.

[0030] The adaptive control method for bed pressure in a fluidized bed boiler, implemented according to the fluidized bed boiler control system, comprises the following steps: The pressure value P1_actual in the dense phase region is collected in real time by the bed pressure detection unit. Compare the actual bed pressure value P1_actual in the dense phase region with the pressure value P2_actual in the dilute phase region to calculate the bed differential pressure ΔP. A fuzzy PID control algorithm is adopted to dynamically adjust the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd of the PID controller according to the bed differential pressure ΔP. The output signal of the PID controller running the fuzzy PID control algorithm is dynamically adjusted, and the output signal is used as the basic control quantity u_base(t) for the frequency control of the slag discharge feeder. A feedforward compensation algorithm is introduced. By monitoring the feed flow rate F_in entering the bed in real time, the feedforward compensation amount u_ff(t) is calculated according to the preset feedforward compensation model. Based on the basic control quantity u_base(t) and the feedforward compensation quantity u_ff(t), the final control output u_final(t) is obtained; The final control output u_final(t) is output to the slag discharge feeder, and the discharge rate of the bed material is controlled by the frequency of the conditional slag discharge feeder to maintain the stability of the bed pressure.

[0031] Bed differential pressure ΔP = P2_actual – P1_actual; The final control output is u_final(t) = u_base(t) + u_ff(t).

[0032] The fuzzy PID control algorithm is as follows: The bed differential pressure ΔP is used as the input variable of the fuzzy controller; The bed differential pressure ΔP is fuzzified to convert precise data into fuzzy data. A fuzzy control rule base is established, and fuzzy values ​​of PID parameter corrections ΔKp, ΔKi, and ΔKd are calculated from the fuzzy control rule base based on the fuzzy inference algorithm. The fuzzy values ​​of the PID parameter corrections ΔKp, ΔKi, and ΔKd are defuzzified to obtain the accurate correction values; The precise correction value of the PID parameter correction is adjusted online, and the final correction value is used for fuzzy PID control.

[0033] In the fuzzy control rule base, direct values ​​are assigned to the correction values ​​of each PID parameter. The values ​​of each PID parameter correction value constitute a fuzzy subset. The method for online correction of PID parameters is as follows: Kp= Kp0 +ΔKp, Ki = Ki0 +ΔKi, Kd = Kd0 +ΔKd In the formula, Kp0, Ki0, and Kd0 are the initial parameters of the PID controller.

[0034] The feedforward compensation model is: u_ff(t) = K×F_in(t – t¹); In the formula, K is the feedforward coefficient and t¹ is the estimated lag time for the feed disturbance to be transmitted to the bed pressure detection point.

[0035] The following description, in conjunction with the accompanying drawings and preferred embodiments, provides further details: In the current embodiment, such as Figure 1 As shown, the fluidized bed boiler system control includes: a flue gas induced draft fan, a cyclone separator, a controller, a feeding unit, a pyrolysis unit, an intermediate silo unit, a primary blower, a fuel system, a slag discharge unit, and the fluidized bed boiler. The controller is connected to the flue gas induced draft fan, the return material unit, the fluidized bed boiler, the fuel system, the slag discharge unit, and the primary blower. The flue gas induced draft fan is connected to the cyclone separator. The feeding unit is connected to the pyrolysis unit. The fluidized bed boiler is connected to the cyclone separator. The fluidized bed boiler is connected to the slag discharge unit. The fluidized bed boiler is connected to the return material unit. The cyclone separator is connected to the pyrolysis unit. The pyrolysis unit is connected to the intermediate silo unit. The primary blower and the fuel system are both connected to the burner of the fluidized bed.

[0036] The hot flue gas generated after combustion carries the solid heat carrier of the fluidized bed boiler into the cyclone separator. The high-temperature flue gas enters the flue gas system through the flue gas induced draft fan. The separated solid heat carrier enters the pyrolysis unit. At the same time, the feeding unit sends the material into the pyrolysis unit. After pyrolysis, the solid heat carrier mixed with the pyrolysis residue enters the intermediate silo unit and is transported back into the solid heat carrier furnace through the return feeder. The combustible substances in the pyrolysis residue will burn in the fluidized bed furnace, while the non-combustible substances remain on the bed.

[0037] The key control points are as follows: A. The frequency control and regulation of the flue gas induced draft fan can stabilize the pressure P2 in the dilute phase zone of the fluidized bed boiler. The frequency of the flue gas induced draft fan and the pressure P2 in the dilute phase zone are constructed into a PID single-loop regulation loop. When the frequency increases, the pressure decreases, and when the frequency decreases, the pressure increases. B. The material level in the intermediate silo is measured using the differential pressure ΔP within the silo. 料仓 Proportional to material level height x Material bulk density x Gravitational acceleration, ΔP, is relatively constant due to the relatively constant bulk density of the material during stable operation.料仓 This directly reflects the material level. L1 and L2 represent two material level measuring points in the silo. When the material level continuously increases and exceeds L1, the frequency of the return feeder will be increased, and the material level in the silo will gradually decrease until it reaches the optimal material level height of ∑(L1+L2) / 2. When the material level height is lower than ∑(L1+L2) / 2, the frequency of the return feeder will be reduced to maintain the optimal material level height. Simultaneously, the operating frequency of the return feeder affects the amount of solid heat carrier and reaction residue in the fluidized bed boiler. A slower frequency results in less return material, while a faster frequency results in more return material. The more material F enters the fluidized bed boiler, the larger the pressure measuring point P1 in the dense phase zone; the less material F enters the fluidized bed boiler, the smaller P1 will be. Therefore, the material quantity F of the return feeder affects the magnitude of the pressure P1 in the dense phase zone. Under the condition that the pressure P2 in the dilute phase zone is stable, the material quantity F of the return feeder is a factor affecting the differential pressure ΔP of the bed. C. During the solid heat carrier heating process in a fluidized bed boiler, to ensure the fluidization state within the furnace, the minimum starting frequency of the primary blower is first set to F. min， With the furnace temperature T of the fluidized bed boiler x With the increase in flue gas volume while maintaining a constant primary blower frequency, the furnace heat carrier circulation volume will also increase, and the amount of heat carrier carried away by the high-temperature flue gas will also continuously increase within the same time period; when the furnace temperature T x Each increase in T x+10℃ Then reduce the fuel supply R of the bottom burner. 燃， Until T x The temperature should be restored to within the range required by the process system; conversely, if the furnace temperature decreases, the fuel supply R should be increased according to the temperature change. 燃 until TT x Return to the temperature range required by the process system; D. The drive motor of the slag discharge and distribution device is frequency-controlled. Only by effectively controlling the frequency and slowly discharging slag can the bed pressure be kept stable within a reasonable range. The logic control flow is as follows: S1: Real-time acquisition of the dense phase pressure value P1_actual measured by the bed pressure detection unit; S2: Compare the actual bed pressure value P1_actual in the dense phase region with the pressure value P2_actual in the dilute phase region, and calculate the bed pressure deviation e(t) = P2_actual – P1_actual; S3: A fuzzy PID control algorithm is adopted to dynamically adjust the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd of the PID controller according to the bed pressure deviation e(t); S4: Use the output signal of the PID controller after dynamic adjustment in step S3 as the basic control quantity u_base(t) for the frequency control of the slag discharge feeder. S5: Introduce feedforward compensation control: Real-time monitoring of the feed flow rate F_in entering the bed, and calculation of the feedforward compensation amount u_ff(t) based on the preset feedforward model; S6: Add the basic control quantity u_base(t) to the feedforward compensation quantity u_ff(t) to obtain the final control output u_final(t) = u_base(t) + u_ff(t); S7: Output the final control output u_final(t) to the slag discharge distributor, adjust its frequency, thereby controlling the discharge rate of bed material and maintaining stable bed pressure.

[0038] Furthermore, the specific process of the fuzzy PID control algorithm described in step S3 is as follows: S31: Use the bed pressure deviation e(t) as the input variable of the fuzzy controller; S32: Perform fuzzification processing on the input variable e(t), converting its precise value into a fuzzy value; S33: Establish a fuzzy control rule base, which contains multiple rules expressed in the form of "if e is A, ΔKp is B, ΔKi is C, and ΔKd is D", where A, B, C, and D are the corresponding fuzzy subsets; S34: Based on the fuzzy inference algorithm, calculate the fuzzy values ​​of PID parameter corrections ΔKp, ΔKi, and ΔKd using the rule base; S35: Defuzzify the fuzzy values ​​of ΔKp, ΔKi, and ΔKd to obtain accurate correction values; S36: Correct PID parameters online according to the formula: Kp = Kp0 +ΔKp, Ki = Ki0 +ΔKi, Kd = Kd0 +ΔKd, where Kp0, Ki0, and Kd0 are the initial parameters of the PID controller.

[0039] Further, the feedforward model mentioned in step S5 is: u_ff(t) = K×F_in(t – t¹), where K is the feedforward coefficient, which is determined through experiments or mechanistic models, and t¹ is the estimated lag time of the feed disturbance being transmitted to the bed pressure detection point.

[0040] After the fluidized bed boiler heats the solid heat carrier, the high-temperature flue gas carries the high-temperature heat carrier into a cyclone separator. The separated high-temperature solid heat carrier is then sent to the pyrolysis unit, where it acts as a heat source to pyrolyze and vaporize the material. After the reaction is complete and the heat carrier and pyrolysis residue are cooled, they are returned to the fluidized bed boiler through an intermediate silo unit. The bed differential pressure is the difference between the pressure P1 in the dense phase zone and the pressure P2 in the dilute phase zone of the fluidized bed boiler. In this technical process, the control of the bed differential pressure in the fluidized bed boiler is crucial. Based on the system process characteristics, the fluidized bed boiler bed differential pressure is controlled using the following method: A. The pressure P2 in the dilute phase zone of the fluidized bed boiler is stabilized by controlling and regulating the operating frequency of the flue gas induced draft fan. B. The amount of solid heat carrier and reaction residue entering the fluidized bed boiler is adjusted by controlling the operating frequency of the return feeder. C. During the solid heat carrier heating process in a fluidized bed boiler, the stable fluidization state inside the boiler furnace is ensured by adjusting the frequency of the primary blower and the ratio of fuel quantity. D. By controlling and adjusting the operating frequency of the slag discharge and distribution device, slag is discharged slowly, stabilizing the bed pressure within a reasonable range, so that the bed pressure can be controlled more quickly, smoothly and accurately.

[0041] This embodiment features stable control, strong adaptability, and good anti-interference performance.

[0042] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0043] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A fluidized bed boiler control system, characterized in that: This includes a flue gas induced draft fan, cyclone separator, controller, fuzzy controller, feeding unit, pyrolysis unit, intermediate silo unit, return feeder, primary blower, fuel system, burner, ash discharge distributor, ash discharge unit, and fluidized bed boiler, wherein: The controller is connected to the flue gas induced draft fan, intermediate silo unit, return feeder, fluidized bed boiler, fuel system, and primary blower to transmit control commands. The fuzzy controller is connected to the fluidized bed boiler, slag discharge feeder, and return feeder, and performs fuzzy control based on the upper-level control commands issued by the controller. The flue gas induced draft fan is connected to the cyclone separator, the feeding unit is connected to the pyrolysis unit, the fluidized bed boiler is connected to the cyclone separator, the fluidized bed boiler is connected to the slag discharge feeder, the slag discharge feeder is connected to the slag discharge unit, the fluidized bed boiler is connected to the return feeder, the return feeder is connected to the intermediate silo unit, the cyclone separator is connected to the pyrolysis unit, and the pyrolysis unit is connected to the intermediate silo unit. All of these are used to realize the linkage action between the upper-level and lower-level components. The primary blower and fuel system are both connected to the burner of the fluidized bed boiler.

2. The fluidized bed boiler control system according to claim 1, characterized in that: When the heat carrier in the fluidized bed boiler burns to generate hot flue gas, it carries the heat carrier into the cyclone separator. The hot flue gas is then sent out by the flue gas induced draft fan. The heat carrier enters the pyrolysis unit, and the feeding unit sends the material into the pyrolysis unit. After pyrolysis is completed, the heat carrier mixed with the pyrolysis residue enters the intermediate silo unit and is then transported back into the fluidized bed boiler through the return feeder. The combustible substances in the pyrolysis residue burn in the fluidized bed boiler, while the non-combustible substances remain in the bed layer of the fluidized bed boiler.

3. The fluidized bed boiler control system according to claim 2, characterized in that: The fluidized bed boiler has a pressure measuring point P1 in the upper dense phase zone and a pressure measuring point P2 in the dilute phase zone installed in its external passageway, and a furnace temperature measuring point T is installed inside the furnace. x The signal access controller is used to receive control commands issued by the controller. The pressure measuring point P1 in the upper dense phase zone is used to characterize the amount of material entering the fluidized bed boiler. The stable control of the pressure measuring point P2 in the dilute phase zone of the fluidized bed boiler is achieved by adjusting the frequency of the flue gas induced draft fan. The pressure measuring point P2 in the dilute phase zone and the frequency of the flue gas induced draft fan constitute a single-loop PID control loop.

4. The fluidized bed boiler control system according to claim 3, characterized in that: The material level measurement of the intermediate silo unit is based on the differential pressure ΔP within the silo. 料仓 The material level height, material bulk density, and gravitational acceleration are determined, and the optimal material level height is regulated by controlling the frequency of the return feeder. The amount of material F entering the fluidized bed boiler is proportional to the pressure value at the pressure measuring point P1 in the dense phase zone. Under the condition that the pressure value P2 in the dilute phase zone is stable, the amount of material F in the return feeder is related to the differential pressure ΔP of the bed.

5. The fluidized bed boiler control system according to claim 4, characterized in that: The fluidization state inside the furnace of the fluidized bed boiler is adjusted according to the blower start-up frequency. When the furnace temperature T... x Each increase in T x+10℃ Then reduce the fuel supply R of the bottom burner. 燃 When the temperature inside the furnace is T x Return to the process temperature range; otherwise, if the furnace temperature T x Reduce, adjust fuel supply R according to temperature changes. 燃 Until the temperature inside the furnace reaches T x Return to the process temperature range.

6. A fluidized bed boiler bed pressure adaptive control method implemented by the fluidized bed boiler control system according to claim 5, characterized in that: The pressure value P1_actual in the dense phase region is collected in real time by the bed pressure detection unit. Compare the actual bed pressure value P1_actual in the dense phase region with the pressure value P2_actual in the dilute phase region to calculate the bed differential pressure ΔP. A fuzzy PID control algorithm is adopted to dynamically adjust the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd of the PID controller according to the bed differential pressure ΔP. The output signal of the PID controller running the fuzzy PID control algorithm is dynamically adjusted, and the output signal is used as the basic control quantity u_base(t) for the frequency control of the slag discharge feeder. A feedforward compensation algorithm is introduced. By monitoring the feed flow rate F_in entering the bed in real time, the feedforward compensation amount u_ff(t) is calculated according to the preset feedforward compensation model. Based on the basic control quantity u_base(t) and the feedforward compensation quantity u_ff(t), the final control output u_final(t) is obtained; The final control output u_final(t) is output to the slag discharge feeder, and the discharge rate of the bed material is controlled by the frequency of the conditional slag discharge feeder to maintain the stability of the bed pressure.

7. The fluidized bed boiler bed pressure adaptive control method according to claim 6, characterized in that: The bed differential pressure ΔP = P2_actual – P1_actual; The final control output is u_final(t) = u_base(t) + u_ff(t).

8. The fluidized bed boiler bed pressure adaptive control method according to claim 6, characterized in that: The fuzzy PID control algorithm is as follows: The bed differential pressure ΔP is used as the input variable of the fuzzy controller; The bed differential pressure ΔP is fuzzified to convert precise data into fuzzy data. A fuzzy control rule base is established, and fuzzy values ​​of PID parameter corrections ΔKp, ΔKi, and ΔKd are calculated from the fuzzy control rule base based on the fuzzy inference algorithm. The fuzzy values ​​of the PID parameter corrections ΔKp, ΔKi, and ΔKd are defuzzified to obtain the accurate correction values; The precise correction value of the PID parameter correction is adjusted online, and the final correction value is used for fuzzy PID control.

9. The fluidized bed boiler bed pressure adaptive control method according to claim 8, characterized in that: In the fuzzy control rule base, direct values ​​are assigned to the correction values ​​of each PID parameter. The values ​​of each PID parameter correction value constitute a fuzzy subset. The method for online correction of PID parameters is as follows: Kp= Kp0 +ΔKp, Ki = Ki0 +ΔKi, Kd = Kd0 +ΔKd In the formula, Kp0, Ki0, and Kd0 are the initial parameters of the PID controller.

10. The fluidized bed boiler bed pressure adaptive control method according to claim 9, characterized in that: The feedforward compensation model is: u_ff(t) = K×F_in(t – t¹); In the formula, K is the feedforward coefficient and t¹ is the estimated lag time for the feed disturbance to be transmitted to the bed pressure detection point.

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