Balanced coal feeding control method for preventing blockage of direct-fired pulverizing system

Abstract

The invention discloses a balanced coal feeding control method for preventing blockage of a direct-fired pulverizing system. The method comprises the following steps that a coal feeder instruction upper limit is manually set on the basis of each coal mill, the coal feeder instruction upper limit is dynamically adjusted according to an air-coal ratio parameter of each coal mill, and the phenomenon of mill blockage caused by insufficient primary air volume or overlarge coal stored in the coal mill in the dynamic load adjustment process is prevented; a coal feeding instruction balance algorithm is set, so that each coal feeder in an automatic state is increased or decreased in proportion in respective upper and lower limit ranges along with a fuel main control instruction; and according to coal feeder upper limit dynamic adjustment and manual offset setting upper and lower limit judgment functions in the automatic state, when an actual coal feeding instruction reaches a limit value, boiler master control is switched to track the actual coal feeding amount, and fuel instruction idle stroke is avoided. On the basis of the coal feeder quantity of the coal mill after balance limitation, mill blockage caused by the maximum output change of the coal mill in unit operation is avoided, and the load dynamic response performance of a thermal power generating unit and the stability of equipment operation are improved.

Description

technical field [0001] The invention relates to the field of boiler master control of a thermal power unit unit coordination control system, in particular to a thermal power unit unit boiler master control method for preventing grinding blockage in a direct-blown pulverizing system. Background technique [0002] The boiler main control and fuel main control in the thermal power generation unit are the core control units of the entire coordinated control system, and their output commands directly act on the coal supply control commands to control the coal volume entering the coal mill. As power grid dispatching has higher requirements on the AGC adjustment function of thermal power units, the units generally set a higher load changing rate in order to quickly respond to AGC's load instructions. Due to the inherent large delay and large inertia characteristics in the process of boiler pulverization, combustion and heat transfer, the main control of the boiler generally adopts ...

AI Technical Summary

Problems solved by technology

Due to the inherent large delay and large inertia characteristics in the process of boiler pulverization, combustion and heat transfer, the main control of the boiler generally adopts the method of drastic increase and decrease of fuel volume and primary air volume in the process of rapid load change to quickly change the combustion conditions of the boiler to improve The response speed of the boiler, and in order to reduce the operating cost of the power plant, it has become a common phenomenon to use coal with a calorific value lower than the design coal type, which leads to the long-term high-load operation of the coal mill output, and the operating personnel are usually for each coal mill Set a conservative output upper limit. During the process of large load fluctuations, the output of the coal mill is very likely to be limited, or the coal mill is blocked.

[0003] Through the analysis of the operating condition data under the coordinated control mode of the unit, it is found that the output of coal mills in different combustion layers is different. Generally, the output of the lower coal mill is greater than that of the upper coal mill, and with the change of equipment health and air leakage, The upper limit of the output of the same coal mill changes accordingly, and the operator manually sets different upper limits of coal feeding according to the output of different coal mills. The time when the coal feeder reaches the upper limit of coal feeding is not synchronized, resulting in a change in the number of coal feeders participating in the adjustment in the upper section of the fuel master control instruction, which affects the tracking performance of the fuel amount; at the same time, the operator manually sets the coal feeding upper limit of different coal mills It often cannot accurately reflect the actual output upper limit of the coal mill, especially in the process of rapid changes in fuel volume, the process of coal feeding and pulverization lags behind the change process of the primary air volume, resulting in the coal feeder being unable to grind coal according to the upper limit of the output of the coal mill. The dynamic coal storage inside the machine quickly adjusts the coal supply

[0004] Through the analysis of the control strategy of the existing coordinated control system, the main control of the fuel will block the main control of the boiler after reaching the upper limit of the command, but due to the different settings of the upper limit of the coal supply, the upper limit of the command of the main fuel control cannot match the actual coal supply in the automatic state When the actual coal supply command reaches the upper limit, the boiler main control command cannot track the actual coal quantity, resulting in the expansion of the command empty stroke and the difference in the return stroke of the command, which affects the coordinated control performance of the unit

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