Bed temperature control system and method for supercritical CFB (circulating fluid bed) boiler

Abstract

The invention discloses a bed temperature control system and method for a supercritical CFB (circulating fluid bed) boiler. The bed temperature control system for the supercritical CFB boiler can comprise multiple groups of bed temperature control devices, wherein each group of bed temperature control device can comprise a cyclone separator arranged in steel frame auxiliary spans on two sides of a hearth as well as a return device and an external bed which are arranged below the cyclone separator, a heat exchanger for controlling the bed temperature is arranged in the external bed, a material separated from the cyclone separator enters the return device, the material in the return device is divided into two parts, one part directly returns to a hearth of the supercritical CFB boiler, and the other part returns to the hearth after passing the external bed; and feedforward of boiler load can act on a valve of the return device, and a slight oscillation signal is overlapped on a control signal of the valve. According to the bed temperature control system and method for the supercritical CFB boiler, the bed temperature control can rapidly respond to the actual working conditions and is independent of reheating steam temperature adjustment, and the stable, rapid and accurate bed temperature control is realized.

Description

technical field [0001] The invention relates to the field of supercritical CFB boilers, in particular to a supercritical CFB boiler bed temperature control system and control method. Background technique [0002] Supercritical unit means that the main steam pressure at the outlet of the superheater exceeds 22.129MPa. It is theoretically believed that when the state parameters of water reach the critical point (pressure 22.129MPa, temperature 374°C), the complete vaporization of water will be completed in an instant. The supercritical once-through boiler has no steam drum, and the start and stop speed is fast. Compared with the thermal efficiency of subcritical thermal power units with the same capacity, theoretically using supercritical parameters can increase the efficiency by 2%-2.5%. [0003] Circulating fluidized bed (CFB) is a new generation of high-efficiency, low-pollution and clean combustion technology developed internationally in recent years. The movement is st...

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Problems solved by technology

[0006] In the current ultra-high temperature CFB combustion control, bed temperature control and reheat steam temperature adjustment are usually coupled with each other, and the control factors of bed temperature and reheat steam temperature interfere with each other, which is not conducive to stably controlling the bed temperature within the target range

At the same time, in order to accurately control the bed temperature, it is necessary to make a decision after comprehensively considering multiple factors that affect the bed temperature, which makes the decision-making time longer, resulting in a certain delay in the control operation than the real-time working condition, which is also a defect of the current bed temperature control

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