Control method for participating fuel master control based on coal slurry blending in circulating fluidized bed boiler

Abstract

The present invention discloses a control method based on the participation of coal sludge blending in the fuel main control of a circulating fluidized bed boiler. According to the present invention, the output after calculation of the coal sludge conversion adjustment coefficient and the total fuel feedback of the original fuel main control are summed and participate in the fuel main control. Under the condition that the fuel instruction remains unchanged, since the coal sludge conversion amount participates in the total fuel feedback, the total fuel amount after the coal sludge participates in the conversion will be 8t / h more than the total fuel feedback of the original fuel main control. After the fuel main control regulator, the total amount of coal feeder instruction will be reduced by 8t / h of coal amount, thereby realizing fuel balance and economic blending in the coal sludge blending process. Since the coal sludge blending causes boiler overpressure, the operating personnel can adjust the coal sludge conversion adjustment coefficient according to the working conditions, thereby realizing the stable regulation function of the unit under the disturbance of coal sludge blending.

Description

Technical Field

[0001] The present invention relates to the technical field of coal slime co-firing control for generator boilers, and in particular to a control method for participating in fuel master control based on coal slime co-firing in circulating fluidized bed boilers. Background Art

[0002] Currently, circulating fluidized bed boilers (CFBs) have a wide range of fuel adaptability. They can burn not only anthracite and bituminous coal, but also coal gangue and coal slime. Even different coal qualities can be mixed in the same boiler. Coal slime combustion technology has matured, and some CFB power plants are already using coal slime for power generation, generating significant economic benefits. However, the stability of coal slime blending has not been fully resolved. The main technical challenges lie in calculating the boiler coal quantity based on the calorific value of coal slime and how to adjust the amount of blended coal slime to control the boiler's fuel flow. This process requires not only ensuring environmental protection requirements, but also considering the safety, stability, and affordability of boiler combustion. Summary of the Invention

[0003] The purpose of the present invention is to remedy the defects of the existing technology and provide a control method based on the main control of coal sludge blending in a circulating fluidized bed boiler.

[0004] The present invention is achieved through the following technical solutions:

[0005] A control method for participating in the main control of fuel based on coal slurry blending in a circulating fluidized bed boiler includes the following logical steps:

[0006] Step 1: Build a function block (FUNCTION) that converts the slurry pump delivery frequency into the standard coal quantity (F(x)) for the fuel master control input. Use the slurry pump delivery frequency feedback as the FUNCTION block's IN1 input. Build a TRANSFER switch block and constant block A1, using the FUNCTION block's output OUT1 as the TRANSFER switch block's INT1 (YES) input, and constant block A1 as the TRANSFER switch block's INT2 (NO) input. The TRANSFER switch block's judgment condition, FLAG, is determined by the slurry pump's operating status and the on / off button through an AND relationship. When the slurry pump is enabled and the fuel master control function is running, the switch block's judgment condition, FLAG, is 1, and the TRANSFER switch block's output, OUT2, is INT1 (YES). When the slurry pump is disabled or the fuel master control function is not running, the TRANSFER switch block's judgment condition, FLAG, is 0, and the TRANSFER switch block's output, OUT2, is INT2 (NO).

[0007] Step 2: Build the MULTIPLY function block and the SETPOINT analog setting function block. Use the TRANSFER switch block output OUT2 from Step 1 as INT1 of the MULTIPLY function block, and the SETPOINT analog setting function block output as INT2 of the MULTIPLY function block. Build the RATELIMIT rate limit function block, using the MULTIPLY multiplication function block output as the RATELIMIT rate limit function block input and the RATELIMIT rate limit function block output as OUT3.

[0008] Step 3: Build the SUM function block. Use the RATELIMIT function block output (OUT3) from Step 2 as INT1 for the SUM function block. Use the total fuel feedback from the original fuel control as INT2 for the SUM function block. The SUM function block output (OUT4) is the total fuel amount after the coal slime is converted. Using the SUM function block output (OUT4) as the controlled variable for the fuel control, the coal slime blending and fuel control function is implemented.

[0009] In step 1, the constant block A1 is 0.

[0010] The function block F(x) for converting the slurry pump delivery frequency into the standard coal volume of the fuel master control input in step 1 is as follows: X1=0, Y1=0; X2=15, Y2=3.5; X3=30, Y3=8; X4=35, Y4=10; X5=50, Y5=15, where X represents the slurry pump delivery frequency feedback, and Y represents the slurry volume delivered by the slurry pump at that frequency converted to standard coal volume. That is, when the slurry pump delivery frequency feedback is X=15 Hz, the slurry volume delivered by the slurry pump at that frequency converted to standard coal volume is Y=3.5 t / h. (This function calculates the conversion amount by analyzing the actual slurry volume delivered by the slurry pump at various operating frequencies, the average calorific value of the slurry, and the operator's switching factor adjustment. Each power plant should conduct experiments and adjust the function accordingly.)

[0011] In step 2, the high limit value of the SETPOINT analog setting function block is 2, and the low limit value is 0.5.

[0012] The advantages of the present invention are as follows: the output after calculating the coal slime conversion adjustment coefficient is summed with the total fuel feedback of the original fuel master control and then included in the fuel master control. When the fuel instruction remains unchanged, the coal slime conversion amount is included in the total fuel feedback, thereby achieving fuel balance and economical blending in the coal slime blending process;

[0013] During the operation of the present invention, if the boiler operating condition causes boiler overpressure due to coal slime co-firing, the operator can adjust the coal slime conversion adjustment coefficient according to the operating condition to achieve the stable regulation function of the unit under the disturbance of coal slime co-firing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention provides a SAMA logic diagram for the implementation of a control method for the main control of coal sludge blending and participating fuel in a circulating fluidized bed boiler. DETAILED DESCRIPTION

[0015] The following describes in detail the control method for the main control of coal sludge blending and participating fuel in a circulating fluidized bed boiler according to the present invention through an embodiment in conjunction with the accompanying drawings:

[0016] A control method for participating in the main control of fuel based on coal slurry blending in a circulating fluidized bed boiler includes the following logical steps:

[0017] Step 1: Build a function block (FUNCTION) that converts the slurry pump delivery frequency into the standard coal quantity F(x) input for the fuel master control. Use the slurry pump delivery frequency feedback as the IN1 input of the FUNCTION block. Build a TRANSFER switch block and constant block A1. Use the FUNCTION block output OUT1 as the INT1 (YES) input of the TRANSFER switch block, and constant block A1 as the INT2 (NO) input of the TRANSFER switch block. Constant block A1 is set to 0. The TRANSFER switch block's judgment condition FLAG is determined by the slurry pump's operating status and the on / off button through an AND relationship. When the slurry pump is enabled and the fuel master control function is running, the switch block's judgment condition FLAG is 1, and the TRANSFER switch block's output OUT2 is INT1 (YES). When the slurry pump is disabled or the slurry pump is not running, the TRANSFER switch block's judgment condition FLAG is 0, and the TRANSFER switch block's output OUT2 is INT2 (NO).

[0018] Step 2: Build the MULTIPLY multiplication function block and the SETPOINT analog setting function block. Set the SETPOINT analog setting function block's high limit to 2 and its low limit to 0.5. Use the TRANSFER switch block's output OUT2 from Step 1 as INT1 for the MULTIPLY multiplication function block, and the SETPOINT analog setting function block's output as INT2 for the MULTIPLY multiplication function block. Build the RATELIMIT rate limit function block, using the MULTIPLY multiplication function block's output as the RATELIMIT rate limit function block's input. The RATELIMIT rate limit function block's output is OUT3.

[0019] Step 3: Build the SUM function block. Use the RATELIMIT function block output (OUT3) from Step 2 as INT1 for the SUM function block. Use the total fuel feedback from the original fuel control as INT2 for the SUM function block. The SUM function block output (OUT4) is the total fuel amount after the coal slime is converted. Using the SUM function block output (OUT4) as the controlled variable for the fuel control, the coal slime blending and fuel control function is implemented.

[0020] In step 1, the function block F(x) in the function block FUNCTION is as follows: X1=0, Y1=0; X2=15, Y2=3.5; X3=30, Y3=8; X4=35, Y4=10; X5=50, Y5=15, where X represents the slurry pump's delivery frequency feedback, and Y represents the amount of slurry delivered by the slurry pump at that frequency converted to standard coal. That is, when the slurry pump's delivery frequency feedback is X=15 Hz, the amount of slurry delivered by the slurry pump at that frequency converted to standard coal is Y=3.5 t / h. (This function calculates the conversion amount by analyzing the actual slurry volume delivered by the slurry pump at various frequencies in the power plant, the average calorific value of the slurry, and the operator's switching factor adjustments. Each power plant should conduct experiments and adjust the corresponding function based on actual conditions.)

[0021] Example 1: When the coal slurry pump is running at a frequency of 30HZ, and the operator puts coal slurry into the fuel master control function, the coal slurry conversion adjustment coefficient is 1. At this time, the FUNCTION block output OUT is 8t / h. Since the coal slurry participates in the fuel master control function and the coal slurry pump is running, the TRANSFER switching block judgment condition FLAG output is 1, and the TRANSFER switching block output OUT2 is YES input, that is, 8t / h; after the coal slurry conversion adjustment coefficient is calculated, the output is summed with the total fuel feedback of the original fuel master control and participates in the fuel master control. When the fuel instruction remains unchanged, since the coal slurry conversion amount participates in the total fuel feedback, the total fuel amount after the coal slurry participates in the conversion will be 8t / h more than the total fuel feedback of the original fuel master control. After the fuel master control regulator, the total amount of coal feeder instruction will be subtracted by 8t / h of coal, thereby realizing fuel balance and economic blending in the coal slurry blending process.

[0022] Example 2: Based on Example 1, when the boiler operating condition is overpressured due to coal slime co-firing during operation, it means that the coal slime converted calorific value exceeds the calorific value of 8t / h of coal. The operator can adjust the coal slime conversion adjustment coefficient according to the operating conditions, and adjust the coefficient from 1 to 1.5. At this time, the output after calculation of the coal slime conversion adjustment coefficient is 12t / h. Compared with Example 1, the total amount of coal feeder instructions will be reduced by 4t / h of coal after the fuel master control, thereby realizing the stable adjustment function of the unit under the disturbance of coal slime co-firing.

Claims

1. A control method for controlling the main fuel of coal sludge blending in a circulating fluidized bed boiler, characterized by: The specific steps include: Step 1: Build the function block FUNCTION for converting the coal slurry pump delivery frequency into the standard coal quantity F(x) of the fuel master control adjustment input, and use the coal slurry pump delivery frequency feedback as the IN1 input of the FUNCTION function block; build the TRANSFER switching block and constant block A1, and use the FUNCTION function block output OUT1 as the INT1 input of the TRANSFER switching block, and the constant block A1 as the INT2 input of the TRANSFER switching block; the TRANSFER switching block judgment condition FLAG is judged by the coal slurry pump operation status and the switching button through the relationship of AND. When the coal slurry participates in the fuel master control function and the coal slurry pump is running, the switching block judgment condition FLAG is 1, and the TRANSFER switching block output OUT2 is INT1. When the coal slurry participates in the fuel master control function cutoff or the coal slurry pump is not running, the TRANSFER switching block judgment condition FLAG is 0, and the TRANSFER switching block output OUT2 is INT2. Step 2: Build the MULTIPLY multiplication function block and the SETPOINT analog setting function block, use the TRANSFER switching block output OUT2 in step 1 as INT1 of the MULTIPLY multiplication function block, and use the SETPOINT analog setting function block output as INT2 of the MULTIPLY multiplication function block; build the RATELIMIT rate limit function block, use the MULTIPLY multiplication function block output as the RATELIMIT rate limit function block input, and the RATELIMIT rate limit function block output as OUT3; Step 3: Build the SUM summation function block, use the output of the RATELIMIT rate limiting function block in step 2 as OUT3 as INT1 of the SUM summation function block, use the total fuel feedback originally participating in the fuel master control as INT2 of the SUM summation function block, and the output OUT4 of the SUM summation function block is the total fuel amount after the coal slime participates in the conversion. Use the output OUT4 of the SUM summation function block as the controlled amount of the fuel master control adjustment, thus realizing the coal slime blending and participating in the fuel master control function; The constant block A1 described in step 1 is 0; The function block F(x) of the standard coal quantity of the fuel master control adjustment input quantity converted from the coal slurry pump delivery frequency feedback in step 1 is set as follows: X1=0, Y1=0; X2=15, Y2=3.5; X3=30, Y3=8; X4=35, Y4=10; X5=50, Y5=15; The high limit value of the SETPOINT analog setting function block described in step 2 is 2, and the low limit value is 0.5.

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