Coal feed amount control method for reducing startup disturbance in hydraulically loaded pulverizing system

Abstract

The present invention relates to a coal feed amount control method for reducing startup disturbance in a hydraulically loaded pulverizing system. The method comprises the following steps: S1. constructing a hydraulically loaded pulverizing system, and controlling a coal feeder which is not yet in operation to execute a coal-spreading starting instruction; S2. upon executing the coal-spreading starting instruction, performing coal spreading on the second coal feeder and recording a coal-spreading time period of the second coal feeder; S3. monitoring an instantaneous coal feed amount feedback value, and using the sum of coal feed amounts of a first coal feeder during the coal-spreading time period as a first total coal feed amount, and on the basis of the first total coal feed amount and a fuel instruction, performing PID control to adjust the coal feed amount of the first coal feeder; and S4. after the coal-spreading time period, the second coal feeder starting normal operation, and PID control being performed on the basis of a second total coal feed amount and the fuel instruction to adjust the coal feed amounts of all operating coal feeders. Compared with the prior art, the present invention can reduce the problem of a significant decrease in coal feed amount caused during a coal-spreading stage when a new coal feeder is put into operation.

Description

A method for controlling coal quantity to reduce start-up disturbances in a hydraulically loaded pulverizing system Technical Field

[0001] This invention relates to the technical field of coal quantity control, and in particular to a coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system. Background Technology

[0002] In normal operation, existing hydraulically loaded pulverizing systems use hydraulic oil to drive the tie rod and pressure frame, bringing the grinding rollers into contact with the coal seam for pulverization. Because hydraulically loaded pulverizing systems rely on high-pressure oil as a power source, they offer advantages over spring-loaded systems, including finer coal powder, wider coal type adaptability, and a smaller amount of gravel. However, direct contact between the grinding rollers and rotating parts is strictly prohibited in this type of system, as excessive loading force can easily damage the equipment. Therefore, during startup, the grinding rollers must first be lifted using the tie rod, with approximately 0.2 tons of coal laid on the grinding bowl, before lowering the rollers to begin grinding.

[0003] The fuel command (FFD) of a normally operating unit is generated by superimposing the boiler command (BD), the water-fuel ratio command, and the BIR (boiler advance acceleration control). The FFD and total fuel quantity (TFF) are processed by PID control to generate the common coal quantity command (CM) for the coal feeder. The total fuel quantity signal is generated by adding the coal quantity of the coal feeders in operation and the fuel oil flow rate.

[0004] Problems with starting up the existing powder making system:

[0005] When a new coal feeder needs to be put into operation, the coal feeder's coal quantity during the coal laying stage of the pulverizer has already been included in the total coal quantity. The other coal feeders will reduce the coal flow during the coal laying stage under the control of the common coal quantity command (CM) to meet the common coal quantity command (CM). However, in reality, the coal flow during the coal laying stage is not converted into coal feed. As a result, when the pulverizer is started up, the coal feed is usually reduced significantly during the load increase process, causing fluctuations in superheat and main / reheat steam temperature. Summary of the Invention

[0006] The purpose of this invention is to provide a coal quantity control method to reduce the significant reduction in coal feed caused by the coal laying stage when a new coal feeder is put into operation. This method reduces the start-up disturbance of the hydraulic loading pulverizing system. By removing the coal flow during the coal laying stage when calculating the total coal feed, the coal flow during the coal laying stage is monitored as an instantaneous coal quantity feedback value but not included in the total coal feed. This ensures that the coal feed of other coal feeders that are already in operation maintains the boiler's demand. Furthermore, the coal flow after the coal laying is completed is re-included in the total coal feed to ensure that the subsequent coal feed meets the public coal quantity command.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for controlling the amount of coal to reduce start-up disturbances in a hydraulically loaded pulverizing system, the method comprising the following steps:

[0009] S1. Construct a pulverizing system with reduced hydraulic loading, the system including a first coal feeder that is working and a second coal feeder that is not yet working, and control the second coal feeder that is not yet working to execute the coal spreading start command.

[0010] S2. After executing the coal spreading start command, spread coal with the second coal feeder and record the coal spreading time period of the second coal feeder;

[0011] S3. During the coal laying period, the actual coal laying amount of the second coal feeder during coal laying is monitored as the instantaneous coal amount feedback value, and the sum of the coal amounts of the first coal feeder during the coal laying period is taken as the first total coal feed. Based on the first total coal feed and the fuel command, PID control is performed to adjust the coal amount of the first coal feeder.

[0012] S4. After the coal laying period, the second coal feeder starts to work normally. The sum of the coal quantity of the first coal feeder and the coal quantity of the second coal feeder after the coal laying period is taken as the second total coal quantity. Based on the second total coal quantity and the fuel command, PID control is performed to adjust the coal quantity of all working coal feeders.

[0013] Furthermore, the amount of coal fed by the coal feeder during operation is the amount of coal output by the coal feeder per unit hour.

[0014] Furthermore, the instantaneous coal quantity feedback value is the amount of coal laid on the grinding bowl of the second coal feeder per unit hour.

[0015] Furthermore, the duration of the coal laying time period is the preset total weight of coal laid divided by the preset coal quantity per unit hour of the second coal feeder during coal laying.

[0016] Furthermore, the specific steps for monitoring the actual coal feeding amount of the second coal feeder during coal feeding as the instantaneous coal feeding feedback value are as follows:

[0017] During the coal laying period, the actual amount of coal laid by the second coal feeder is obtained as the instantaneous coal quantity feedback value. If the instantaneous coal quantity feedback value exceeds the threshold, a coal laying problem reminder signal is issued.

[0018] Furthermore, the threshold is a fixed value.

[0019] Furthermore, the first coal feeder is one or more coal feeders in operation.

[0020] Furthermore, the second coal feeder may be one or more.

[0021] Furthermore, the specific steps for spreading coal on the second coal feeder are as follows:

[0022] During the coal spreading period, the grinding roller of the second coal feeder is lifted by the pull rod to spread coal onto the grinding bowl of the second coal feeder.

[0023] Furthermore, the specific steps for the second coal feeder to begin normal operation after the coal laying period are as follows:

[0024] After the coal laying period, the grinding rollers of the second coal feeder are lowered to begin grinding.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention removes the coal flow during the coal laying stage when calculating the total coal feed rate. The coal flow during the coal laying stage is monitored as an instantaneous coal quantity feedback value but not included in the total coal feed rate. This ensures that the coal feed rate of other coal feeders that were originally working maintains the boiler's demand. Furthermore, the coal flow after the coal laying is completed is re-included in the total coal feed rate to ensure that the subsequent coal feed rate meets the public coal quantity command. Attached Figure Description

[0027] Figure 1 is a flowchart of the present invention. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0029] To overcome the problem that when a new coal feeder needs to be put into operation, the coal flow of the feeder during the coal laying stage of the pulverizer is already included in the total coal flow. The other feeders, under the control of the common coal flow command (CM), will reduce the coal flow during the coal laying stage to meet the common coal flow command (CM). However, in reality, the coal flow during the coal laying stage is not converted into coal feed, resulting in a significant reduction in coal feed during the load increase process when the pulverizer is started up. This causes fluctuations in superheat and main / reheat steam temperatures. This invention proposes a coal flow control method to reduce start-up disturbances in a hydraulically loaded pulverizing system. The flowchart of the method is shown in Figure 1. The method includes the following steps:

[0030] S1. Construct a pulverizing system with reduced hydraulic loading, the system including a first coal feeder that is working and a second coal feeder that is not yet working, and control the second coal feeder that is not yet working to execute the coal spreading start command.

[0031] S2. After executing the coal spreading start command, spread coal with the second coal feeder and record the coal spreading time period of the second coal feeder;

[0032] S3. During the coal laying period, the actual coal laying amount of the second coal feeder during coal laying is monitored as the instantaneous coal amount feedback value, and the sum of the coal amounts of the first coal feeder during the coal laying period is taken as the first total coal feed. Based on the first total coal feed and the fuel command, PID control is performed to adjust the coal amount of the first coal feeder.

[0033] S4. After the coal laying period, the second coal feeder starts to work normally. The sum of the coal quantity of the first coal feeder and the coal quantity of the second coal feeder after the coal laying period is taken as the second total coal quantity. Based on the second total coal quantity and the fuel command, PID control is performed to adjust the coal quantity of all working coal feeders.

[0034] The amount of coal fed by the coal feeder during operation is the amount of coal output by the coal feeder per unit hour.

[0035] The instantaneous coal quantity feedback value is the amount of coal laid on the grinding bowl of the second coal feeder per unit hour.

[0036] The duration of the coal laying period is the preset total weight of coal laid divided by the preset coal quantity per hour of the second coal feeder during coal laying.

[0037] The specific steps for monitoring the actual coal feeding amount of the second coal feeder during coal feeding as the instantaneous coal feeding feedback value are as follows:

[0038] During the coal laying period, the actual amount of coal laid by the second coal feeder is obtained as the instantaneous coal quantity feedback value. If the instantaneous coal quantity feedback value exceeds the threshold, a coal laying problem reminder signal is issued.

[0039] The threshold is a fixed value.

[0040] The first coal feeder is one or more coal feeders in operation.

[0041] The second coal feeder may be one or more.

[0042] The specific steps for spreading coal on the second coal feeder are as follows:

[0043] During the coal spreading period, the grinding roller of the second coal feeder is lifted by the pull rod to spread coal onto the grinding bowl of the second coal feeder.

[0044] The specific steps for the second coal feeder to start normal operation after the coal laying period are as follows:

[0045] After the coal laying period, the grinding rollers of the second coal feeder are lowered to begin grinding.

[0046] In this invention, during the coal laying process, the coal feeder maintains a coal rate of 0 t / h. After a 40-second delay, calculations are performed based on the instantaneous coal rate feedback. Simultaneously, the instantaneous coal rate feedback value is introduced to monitor whether coal feeding is smooth during the pulverizer startup process, but this is not included in the total fuel quantity. The instantaneous coal rate feedback monitors the coal flow (at this point, it is 17.92 t / h), but since the coal feeder's coal rate is 0 t / h during the coal laying stage, it is not included in the total fuel. Only after coal laying is completed, i.e., after a 40-second delay, when the coal feeder reaches the instantaneous coal rate feedback value at a certain rate, is the total coal feed calculation initiated, and the coal quantity of the remaining pulverizers is reduced via CM (Compressive Control).

[0047] By means of the method of the present invention, when a new coal feeder is introduced to work, the coal quantity of the original coal feeder will not drop suddenly, preventing the coal quantity of the subsequent unit from being greatly reduced during the load increase process, reducing superheat and main / reheat steam temperature disturbances, effectively avoiding false coal quantity entering the boiler during the coal laying stage of the pulverizing system startup, which would greatly reduce superheat and cause unstable unit operation conditions, while improving the safety and stability of the unit.

[0048] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for controlling the amount of coal to reduce start-up disturbance in a hydraulically loaded pulverizing system, characterized in that, The method includes the following steps: S1. Construct a pulverizing system with reduced hydraulic loading, the system including a first coal feeder that is working and a second coal feeder that is not yet working, and control the second coal feeder that is not yet working to execute the coal spreading start command. S2. After executing the coal spreading start command, spread coal with the second coal feeder and record the coal spreading time period of the second coal feeder; S3. During the coal laying period, the actual coal laying amount of the second coal feeder during coal laying is monitored as the instantaneous coal amount feedback value, and the sum of the coal amounts of the first coal feeder during the coal laying period is taken as the first total coal feed. Based on the first total coal feed and the fuel command, PID control is performed to adjust the coal amount of the first coal feeder. S4. After the coal laying period, the second coal feeder starts to work normally. The sum of the coal quantity of the first coal feeder and the coal quantity of the second coal feeder after the coal laying period is taken as the second total coal quantity. Based on the second total coal quantity and the fuel command, PID control is performed to adjust the coal quantity of all working coal feeders.

2. The coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 1, characterized in that, The amount of coal fed by the coal feeder during operation is the amount of coal output by the coal feeder per unit hour.

3. The coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 1, characterized in that, The instantaneous coal quantity feedback value is the amount of coal laid on the grinding bowl of the second coal feeder per unit hour.

4. The coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 3, characterized in that, The duration of the coal laying period is the preset total weight of coal laid divided by the preset coal quantity per hour of the second coal feeder during coal laying.

5. The coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 4, characterized in that, The specific steps for monitoring the actual coal feeding amount of the second coal feeder during coal feeding as the instantaneous coal feeding feedback value are as follows: During the coal laying period, the actual amount of coal laid by the second coal feeder is obtained as the instantaneous coal quantity feedback value. If the instantaneous coal quantity feedback value exceeds the threshold, a coal laying problem reminder signal is issued.

6. The coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 5, characterized in that, The threshold is a fixed value.

7. The coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 1, characterized in that, The first coal feeder is one or more coal feeders in operation.

8. The coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 1, characterized in that, The second coal feeder may be one or more.

9. The coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 1, characterized in that, The specific steps for spreading coal on the second coal feeder are as follows: During the coal spreading period, the grinding roller of the second coal feeder is lifted by the pull rod to spread coal onto the grinding bowl of the second coal feeder.

10. A coal quantity control method for reducing start-up disturbances in a hydraulically loaded pulverizing system according to claim 8, characterized in that, The specific steps for the second coal feeder to start normal operation after the coal laying period are as follows: After the coal laying period, the grinding rollers of the second coal feeder are lowered to begin grinding.

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