A control method for a drum feeder of a circulating fluidized bed waste incinerator

Abstract

The present invention discloses a control method for a drum feeder of a circulating fluidized bed waste incinerator, which overcomes the problems of less consideration and inaccurate control in the prior art for the feeder control, and includes the following steps: S1: Collect data of the circulating fluidized bed, and process the collected data to generate sub-control instructions; S2: Use a multivariable control algorithm, input the sub-control instructions, and output the frequency control instructions for the drum feeder; S3: Control the operation of the drum feeder according to the frequency control instructions for the drum feeder, and the frequency control instructions for the drum feeder control the output frequency of the drum feeder to be 18% - 30% of the maximum frequency. It can ensure that the waste is continuously and evenly fed into the furnace for combustion, thereby improving the stability of the combustion condition of the boiler.

Description

Technical Field

[0001] The present invention relates to the technical field of waste treatment, and particularly relates to a control method for a rotary feeder of a circulating fluidized bed waste incinerator. Background Art

[0002] The function of the rotary feeder of the circulating fluidized bed waste incinerator is to continuously and evenly feed waste into the furnace through the internal spiral blades for combustion. The rotational speed of the drum is generally 10 - 60% of the maximum speed. The original control was mainly manually controlled by operators, and mainly intervened and adjusted according to the changes in the furnace outlet pressure, the oxygen content in the tail gas (5% - 12%), and the CO emission (<100 mg / m³).

[0003] At present, the control method of waste feeding amount mainly uses the ultrasonic level measurement plus the weighing of the waste hopper. Through internal operation, the current waste feeding speed is calculated to realize the automatic operation of waste feeding. There is also a method of directly controlling the speed of the feeder to control the uniform and stable feeding of waste. For example, on October 26, 2016, the Chinese Patent Office disclosed an invention named a control method and device for a waste feeder of a waste incinerator, with the publication number CN106051783B. The control method for the waste feeder of the waste incinerator in this invention includes: obtaining the total forward feeding stroke and the preset number of forward feeding steps of the waste feeder; dividing the total forward feeding stroke by the preset number of forward feeding steps to obtain the forward feeding sub-stroke; calculating the preset residence time of the waste feeder; controlling the waste feeder to perform feeding once every preset residence time, and the forward distance of each feeding is the forward feeding sub-stroke. Through the above method, it is possible to avoid the accumulation of waste in the drying section of the grate, improve the stability of the incineration process, thereby improving the combustion efficiency of the incinerator and improving the operation safety of the incinerator. And because the accumulation of waste in the drying section of the grate is avoided, the situation of excessive pollution emissions is improved, and the emission of pollutants is reduced. However, this invention only achieves the purpose by controlling the forward stroke of the feeder, and does not consider the influence of environmental factors. As the final link of feeding, the quality of its control performance is directly related to the performance of the combustion system, and has a greater impact on the fluctuations of parameters such as the circulating fluidized bed temperature, the return material temperature, the furnace temperature, the steam volume, the oxygen content in the flue gas, the CO emission, and the furnace pressure. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art, and provide a control method for a rotary feeder of a circulating fluidized bed waste incinerator, which can ensure that waste is continuously and evenly fed into the furnace for combustion, thereby improving the stability of the combustion condition of the boiler.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A control method for a rotary feeder of a circulating fluidized bed waste incinerator, which includes the following steps:

[0006] S1: Collect the data of the circulating fluidized bed, and process the collected data to generate sub-control instructions;

[0007] S2: Use the multivariable control algorithm, input the sub-control instructions, and output the frequency control instruction of the roller feeder;

[0008] S3: Control the operation of the roller feeder according to the frequency control instruction of the roller feeder. The frequency control instruction of the roller feeder controls the output frequency of the roller feeder to be 18%-30% of the maximum frequency.

[0009] The present invention utilizes the multivariable coordinated control technology, and through the coordinated control of multiple sub-control instructions, generates the final frequency control instruction of the roller feeder, which can ensure that the garbage is continuously and evenly fed into the furnace for combustion, thereby improving the stability of the boiler combustion condition, greatly improving the uniformity of the continuous feeding of the roller feeder of the circulating fluidized bed waste incinerator, and improving the stability of the working condition of the circulating fluidized bed waste incinerator.

[0010] Preferably, in the step S1, the data of the circulating fluidized bed collected includes: furnace temperature, steam flow rate, steam flow rate set value, current return material temperature, next moment return material temperature, upper-stage reamer current, roller current, flue gas oxygen content, and CO content. As the final link of feeding, the quality of the control performance of the roller feeder is directly related to the performance of the combustion system, and has a great influence on the fluctuations of parameters such as the circulating fluidized bed temperature, return material temperature, furnace temperature, steam flow rate, flue gas oxygen content, CO emission, and furnace pressure.

[0011] Preferably, in the step S1, the generated sub-control instructions include: steam flow rate correction instruction, return material temperature deviation correction instruction, CO overlimit prediction correction instruction, and furnace positive pressure correction instruction. Through the coordinated control of the sub-control instructions, it can ensure that the garbage is continuously and evenly fed into the furnace for combustion, thereby improving the stability of the boiler combustion condition.

[0012] Preferably, in the step S1, the steam flow rate correction instruction: obtain the steam flow rate set value by collecting the historical big data of the steam flow rate, and use the result of comparing the current steam flow rate with the set value as the steam flow rate correction instruction. If the difference between the steam flow rate and the set value is greater than the threshold value, then issue the steam flow rate correction instruction.

[0013] Preferably, the circulating material temperature deviation correction instruction is obtained by collecting the current circulating material temperature, the current upper reamer current, the drum current, the oxygen content in the flue gas, and the circulating material temperature at the next moment from historical big data, establishing a circulating material temperature prediction model, inputting the current circulating material temperature, the upper reamer current, the drum current, and the oxygen content in the flue gas into the circulating material temperature deviation correction instruction model to obtain the predicted temperature at the next moment, and obtaining the circulating material temperature deviation correction instruction according to the deviation between the predicted value and the actual value. The temperature prediction model is used to predict the temperature at the next moment and compare it with the actual value.

[0014] Preferably, the steps for establishing the reverse material temperature prediction model are as follows:

[0015] a1: Collect the current circulating material temperature, the circulating material temperature at the next moment, the upper reamer current, the drum current, and the oxygen content in the flue gas from historical data;

[0016] a2: Use the current circulating material temperature, the upper reamer current, the drum current, and the oxygen content in the flue gas as inputs, and the circulating material temperature at the next moment as the output, and input them into the neural network model for training to obtain the reverse material temperature prediction model;

[0017] a3: Repeat step a2 to obtain several reverse material temperature prediction models, test the trained models, and select the model with the lowest error rate as the final reverse material temperature prediction model.

[0018] Train multiple models, select the model with the lowest error rate as the final model, and provide the accuracy of the prediction result.

[0019] Preferably, in step S1, the CO overlimit estimation correction instruction: Obtain the change trend of the oxygen content and CO content in the flue gas for a period of time as the CO overlimit estimation correction instruction, which is specifically manifested as: Use an oxygen sensor to detect the oxygen content in the flue gas, use a CO sensor to detect the CO content. If within a specified time, the oxygen content in the flue gas decreases, the CO content increases, and the difference between the measured CO content and the CO content limit exceeds the threshold, then a CO overlimit estimation correction instruction needs to be issued. The CO overlimit estimation correction instruction is used as a feedforward quantity.

[0020] Preferably, in step S1, the furnace positive pressure correction instruction: Obtain the change in the drum current from historical data, obtain the furnace positive pressure from historical data, obtain the reference value of the furnace positive pressure, and use the change in the drum current and the reference value of the furnace positive pressure as the furnace positive pressure correction instruction.

[0021] Preferably, in step S2, the input of the sub-control instruction and the output of the frequency control instruction for the roller feeder include: taking the steam quantity correction instruction as the benchmark, taking the return material temperature deviation correction instruction as the wide-range adjustment, and taking the CO over-limit prediction correction instruction and the furnace positive pressure correction instruction as the dynamic feedforward to obtain the final frequency control instruction for the roller feeder.

[0022] Through multivariable coordinated control, taking the steam quantity set value as the instruction adjustment benchmark and the return material temperature as the wide-range adjustment, on this basis, the fine regulation of the steam quantity is carried out. At the same time, for the fluctuations of the furnace temperature, O2, CO, and the furnace pressure, the dynamic feedforward is applied to the roller instruction to form the final frequency control instruction for the roller feeder. The multivariable control algorithm is a prior art, which is a control method with multiple input or output quantities and adopts control strategies such as multi-step testing, rolling optimization, and feedback correction. Adding feedforward control to multivariable prediction is also visible in the prior art. Through the multivariable control algorithm, the predicted value of the roller feeder frequency is obtained, and thus the frequency control instruction for the roller feeder is generated.

[0023] Therefore, the present invention has the following beneficial effects: 1. Through multivariable coordinated control, taking the steam quantity set value as the instruction adjustment benchmark and the return material temperature as the wide-range adjustment, on this basis, the fine regulation of the steam quantity is carried out; 2. For the fluctuations of the furnace temperature, O2, CO, and the furnace pressure, the dynamic feedforward is applied to the roller instruction, which greatly improves the uniformity of the continuous feeding of the roller feeder of the circulating fluidized bed waste incinerator and improves the stability of the working conditions of the circulating fluidized bed waste incinerator. Description of the Drawings

[0024] Figure 1 It is the specific operation flow chart of the method of the present invention. Detailed Embodiments

[0025] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

[0026] Such as Figure 1In the illustrated embodiment, a control method for a drum feeder of a circulating fluidized bed waste incinerator can be seen. Its operation process is as follows: Step 1, collect data of the circulating fluidized bed and process the collected data to generate sub-control instructions; Step 2, use a multivariable control algorithm, input the sub-control instructions, and output the frequency control instruction for the drum feeder; Step 3, control the operation of the drum feeder according to the frequency control instruction for the drum feeder. The frequency control instruction for the drum feeder controls the output frequency of the drum feeder to be 18% - 30% of the maximum frequency. The present invention utilizes the multivariable coordinated control technology to generate the final frequency control instruction for the drum feeder through coordinated control of multiple sub-control instructions, greatly improving the uniformity of continuous feeding of the drum feeder of the circulating fluidized bed waste incinerator and enhancing the stability of the operating conditions of the circulating fluidized bed waste incinerator.

[0027] Next, the technical solution and technical effect of the present invention will be further illustrated through specific examples.

[0028] Step 1: Collect data of the circulating fluidized bed and process the collected data to generate sub-control instructions

[0029] The data collected from the circulating fluidized bed includes: furnace temperature, steam flow rate, steam flow rate set value, current return material temperature, next moment return material temperature, upper reamer current, drum current, flue gas oxygen content, and CO content. Corresponding processing is performed on the collected data to obtain sub-control instructions including steam flow rate correction instruction, return material temperature deviation correction instruction, CO overlimit prediction correction instruction, and furnace positive pressure correction instruction.

[0030] As the final link of feeding, the control performance of the drum feeder is directly related to the performance of the combustion system and has a great impact on the fluctuations of parameters such as the circulating fluidized bed temperature, return material temperature, furnace temperature, steam flow rate, flue gas oxygen content, CO emissions, and furnace pressure. Through coordinated control of the sub-control instructions, it can ensure that waste is continuously and evenly fed into the furnace for combustion, thereby improving the stability of the boiler combustion conditions.

[0031] The steam flow rate correction instruction obtains the steam flow rate set value by collecting historical big data of the steam flow rate, and uses the result of comparing the current steam flow rate with the set value as the steam flow rate correction instruction. If the difference between the steam flow rate and the set value is greater than the threshold, the steam flow rate correction instruction is issued.

[0032] The return material temperature deviation correction instruction collects the current return material temperature, upper reamer current, drum current, flue gas oxygen content, and next moment return material temperature in historical big data, establishes a return material temperature prediction model, inputs the current return material temperature, upper reamer current, drum current, and flue gas oxygen content into the return material temperature deviation correction instruction model to obtain the predicted temperature at the next moment, and obtains the return material temperature deviation correction instruction according to the deviation between the predicted value and the actual value.

[0033] The steps to establish the prediction model for the temperature of the returned material are as follows:

[0034] a1: Collect the current returned material temperature, the returned material temperature at the next moment, the current of the upper reamer, the current of the drum, and the oxygen content in the flue gas from historical data;

[0035] a2: Use the current returned material temperature, the current of the upper reamer, the current of the drum, and the oxygen content in the flue gas as inputs, and the returned material temperature at the next moment as the output, and input them into the neural network model for training to obtain the prediction model for the temperature of the returned material;

[0036] a3: Repeat step a2 to obtain several prediction models for the temperature of the returned material, test the trained models, and select the model with the lowest error rate as the final prediction model for the temperature of the returned material.

[0037] Train multiple models, select the model with the lowest error rate as the final model, and provide the accuracy of the prediction results.

[0038] By obtaining the change trends of the oxygen content and CO content in the flue gas over a period of time as the CO overlimit prediction and correction instruction, specifically: use an oxygen sensor to detect the oxygen content in the flue gas, use a CO sensor to detect the CO content. If within the specified time, the oxygen content in the flue gas decreases, the CO content increases, and the difference between the measured CO content and the CO content limit exceeds the threshold, then a CO overlimit prediction and correction instruction needs to be issued.

[0039] The returned material temperature deviation correction instruction is obtained by obtaining the change in the drum current from historical data and obtaining the furnace positive pressure from historical data to obtain the reference value of the furnace positive pressure, and using the change in the drum current and the reference value of the furnace positive pressure as the furnace positive pressure correction instruction.

[0040] The second step: Use the multivariable control algorithm, input the sub-control instructions, and output the frequency control instruction for the drum feeder

[0041] Through multivariable coordinated control, with the steam flow correction instruction as the reference, using the returned material temperature deviation correction instruction as the wide-range adjustment, on this basis, perform fine regulation of the steam flow. At the same time, for the fluctuations of the furnace temperature, O2, CO, and furnace pressure, using the CO overlimit prediction and correction instruction and the furnace positive pressure correction instruction as dynamic feedforward, the final frequency control instruction for the drum feeder is obtained. This greatly improves the uniformity of the continuous feeding of the drum feeder of the circulating fluidized bed waste incinerator and improves the stability of the operating conditions of the circulating fluidized bed waste incinerator.

[0042] The third step: Control the operation of the drum feeder according to the frequency control instruction for the drum feeder

[0043] The frequency control command of the drum feeder controls the output frequency of the drum feeder to be 18% - 30% of the maximum frequency, ensuring the continuous and stable operation of the drum feeder.

[0044] The above-described embodiments are only a preferred solution of the present invention and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions described in the claims.

Claims

1. A control method for a drum feeder of a circulating fluidized bed waste incinerator, characterized in that, It includes the following steps: S1: Collect data of the circulating fluidized bed, including furnace temperature, steam flow, steam flow set value, current return material temperature, return material temperature at the next moment, current of the upper reclaimer, current of the drum, oxygen content in the flue gas, and CO content, and process the collected data to generate sub-control instructions, including steam flow correction instruction, return material temperature deviation correction instruction, CO overlimit prediction correction instruction, and furnace positive pressure correction instruction, and coordinate the control of multiple sub-control instructions; S2: Use the multivariable control algorithm, input the sub-control instructions, take the steam flow correction instruction as the benchmark, use the return material temperature deviation correction instruction as a wide-range adjustment, apply dynamic feedforward to the drum instruction for the fluctuations of furnace temperature, O2 and CO, and furnace pressure, and output the frequency control instruction of the drum feeder; S3: Control the operation of the drum feeder according to the frequency control instruction of the drum feeder, and control the output frequency of the drum feeder to be 18%-30% of the maximum frequency.

2. The control method of a drum feeder for a circulating fluidized bed waste incinerator according to claim 1, wherein The control performance of the drum feeder affects the bed temperature, return material temperature, furnace temperature, steam flow, oxygen content in the flue gas, CO emissions, and furnace pressure of the circulating fluidized bed.

3. A control method for a rotary feeder of a circulating fluidized bed waste incinerator according to claim 1, characterized in that, In step S1, the steam flow correction instruction: Obtain the steam flow set value by collecting the steam flow of historical big data, and use the result of comparing the current steam flow with the set value as the steam flow correction instruction.

4. A control method for a drum feeder of a circulating fluidized bed waste incinerator according to claim 1, characterized in that, In step S1, the return material temperature deviation correction instruction: Collect the current return material temperature, current of the upper reclaimer, current of the drum, oxygen content in the flue gas, and return material temperature at the next moment in historical big data, establish a return material temperature prediction model, input the current return material temperature, current of the upper reclaimer, current of the drum, and oxygen content in the flue gas into the return material temperature deviation correction instruction model to obtain the predicted temperature at the next moment, and obtain the return material temperature deviation correction instruction according to the deviation between the predicted value and the actual value.

5. A control method for a drum feeder of a circulating fluidized bed waste incinerator according to claim 4, characterized in that, The steps to establish the return material temperature prediction model are as follows: a1: Collect the current return material temperature, return material temperature at the next moment, current of the upper reclaimer, current of the drum, and oxygen content in the flue gas in historical data; a2: Take the current return material temperature, current of the upper reclaimer, current of the drum, and oxygen content in the flue gas as inputs, and the return material temperature at the next moment as the output, input them into the neural network model for training to obtain the return material temperature prediction model; a3: Repeat step a2 to obtain several return material temperature prediction models, test the trained models, and select the model with the lowest error rate as the final return material temperature prediction model.

6. A control method for a drum feeder of a circulating fluidized bed waste incinerator according to claim 3, characterized in that, In step S1, the CO overlimit prediction correction instruction: Obtain the change trend of oxygen content and CO content in the flue gas for a period of time as the CO overlimit prediction correction instruction, and the specific manifestation is: Use an oxygen sensor to detect the oxygen content in the flue gas, use a CO sensor to detect the CO content, use a current sensor to detect the current of the drum. If the oxygen content in the flue gas decreases, the CO content increases, and the difference between the measured CO content and the CO content limit exceeds the threshold within the specified time, then a CO overlimit prediction correction instruction needs to be issued.

7. A control method for a drum feeder of a circulating fluidized bed waste incinerator according to claim 3, characterized in that, Step S1 mentioned above, furnace positive pressure correction instruction: Obtain the change in drum current from historical data, obtain the furnace positive pressure from historical data, get the reference value of the furnace positive pressure, and use the change in drum current and the reference value of the furnace positive pressure as the furnace positive pressure correction instruction.

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