System and method for improving RB working condition of induced draft fans of two-boiler one-machine thermal power generating unit

Abstract

The invention discloses a system and a method for improving the RB working condition of induced draft fans of a two-boiler one-machine thermal power generating unit. An outlet of a first boiler communicates with one end of a first induced air mother pipe, the other end of the first induced air mother pipe communicates with the input ends of a first induced draft fan and a second induced draft fan, and an outlet of a second boiler communicates with one end of a second induced air mother pipe; the other end of the second induced draft mother pipe communicates with the input end of a third induced draft fan and the input end of a fourth induced draft fan, one end of a communicating pipe communicates with the first induced draft mother pipe, the other end of the communicating pipe communicates with the second induced draft mother pipe, and an electric adjusting valve is arranged on the communicating pipe; and a first pressure transmitter and a second pressure transmitter are respectively arranged on the first boiler and the second boiler, and a PID controller is respectively connected with the first pressure transmitter, the second pressure transmitter and the electric adjusting valve. The problem of induced draft fan RB caused by the fact that only one boiler induced draft fan of a two-boiler-one-machine unit breaks down can be effectively solved.

Description

technical field [0001] The invention relates to the technical field of automatic control of thermal power plants, in particular to a system and method for improving the RB working conditions of induced draft fans of two furnaces and one thermal power unit. Background technique [0002] The function of RB means that in the case of abnormality and failure of the auxiliary machine in operation, the load command of the unit and the fuel amount can be quickly responded, and the main automatic control system of the unit cooperates with each other to quickly and stably reduce the load of the unit to the actual maximum output allowed by the unit , and ensure the continued safe operation of the unit. Among the existing thermal power units, most of the units are equipped with two induced draft fans with 60% rated output (because the induced draft fan and the booster fan of the desulfurization system are combined into one) as the main power output of the air and smoke system of the boi...

AI Technical Summary

Problems solved by technology

[0008] First of all, the load of all auxiliary machines of the entire unit is quickly reduced by 50% at the same time, which brings obvious workload and mental pressure to the operating personnel; the rapid response of equipment is also a great test for the quality of equipment materials, and many times Substantial load changes, the hidden damage to the equipment can not be ignored

[0009] Second, the RB of the induced draft fan occurs, and the air supply system trips an air supply fan in an emergency to match the flow capacity lost by the boiler's air and smoke system. The reduction in air volume caused a large area of ​​unburned pulverized coal to stay in the furnace; however, the extremely unstable aerodynamic field at this time provided opportunities for the pulverized coal to stay in the tail flue of the boiler. As time went on, the tail smoke The pulverized coal that has not been fully burned in the flue will accumulate more and more, and when it reaches a certain level, it will deflagrate instantly in the tail flue, damaging the heat exchange area of ​​the tail flue of the boiler, and bringing irreparable economic losses to the power generation company

[0010] Thirdly, the induced draft fan RB causes the furnace negative pressure to fluctuate violently, and can even reach the limit protection value of the boiler in an instant, or even exceed the limit value, causing the unit to shut down unplanned; although the time for exceeding the limit protection value is not long, it is frequently exceeded. operation, it is also a great test for the life of the material of the boiler

[0011] In the end, RB of the induced draft fan occurred, and the load of the two boilers changed drastically at the same time to maintain the consistency of the steam quality before the parallel valve. If there is a slight carelessness, it will cause unplanned shutdown of the unit, or serious damage to the equipment of the unit, which will bring immeasurable economic losses to the power generation company.

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