Serial combustion system and method for load control of circulating fluidized bed boiler

Abstract

The invention relates to a cycle fluid bed boiler load serial burning control system, which comprises a forecasting unit, a main steam pressure serial control circuit, a coal feeder average rotation speed PID circuit, a one-time wind PID circuit, a secondary wind PID circuit. Wherein, the forecasting unit uses secondary curve as forecast function to forecast the main steam pressure; the main steam pressure serial control circuit comprises an external loop PID circuit and an internal loop PID circuit, to guide the bed temperature signal or/and hearth outlet temperature into internal loop PID circuit as the middle controlled variable; the result of main steam pressure serial control circuit is used as the control order of boiler to be input into the coal feeder average rotation speed PID circuit, the one-time wind PID circuit and the secondary wind PID circuit. The invention also discloses a method for controlling said cycle fluid bed boiler load serial burning control system. The invention can solve the defects of present technique that large over-adjusted main pressure and worse bed temperature stability.

Description

technical field [0001] The invention relates to a fluidized bed combustion control system and method, in particular to a circulating fluidized bed boiler load cascade combustion control system and method. Background technique [0002] Circulating fluidized bed boilers are more and more widely used in the electric power and thermal power industries due to their high combustion efficiency, wide fuel adaptability, and easy to meet the requirements of environmental protection. When the circulating fluidized bed boiler is running, the bed temperature (or the furnace outlet temperature) must be kept within its design range, generally between 850°C and 950°C, within this range, normal fluidization, combustion, and maximum Best desulfurization efficiency, lower NO X yield and higher combustion efficiency. If the bed temperature or furnace outlet temperature is too high, coking will occur in the furnace, and if the temperature is too low, fire will occur. While ensuring the bed te...

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Problems solved by technology

[0007] In order to overcome the problem of serious overshooting of the main steam pressure caused by the large inertia and large hysteresis characteristics of the controlled object of the existing circulating fluidized bed boiler, the present invention uses a simple and practical prediction algorithm to predict the main steam pressure. It is not necessary to establish an accurate model of the controlled object in advance, but only predict the measured value after n operating cycles in the future (hereinafter referred to as the predicted value) based on the measured value at the current moment and the measured value of the past two operating cycles. As an input signal to the main steam pressure cascade control loop

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