Study On Control Technology Of The Bed Temperature Of The Circulating Fluidized Bed Boiler

Circulating Fluidized Bed Boiler(CFBB) is a new technique of high-efficiency,low-pollution and clean combustion developed in recent years in the world ,which has many advantages such as extensive adaption of fuels, low emission of SO₂ and NO_X, simple fuel treatment system,good performance of load adjustment and so on.That is popularized in commerce internationally and there are more than thousand Circulating Fluidized Bed Boiler put to use in our country.But, CFBB is a new type boiler with immature technology till now. It′s main feature is that the material (fuel such as desulphurization agent) is in flowing state during burning. There are some complex characteristics such as non-linearity, uncertainty,time-variety,undue lagging and multi-variable coupling in combustion. It is difficult to automatic control CFBB especially burning control.Bed temperature is important parameter of CFBB control system. Under practical operating condition, the best bed temperature is 850℃～900℃which can eliminate SO₂ and reduce the emission of NO_X. Low bed temperature not only goes down the efficiency of desulphurization but also increase the emission of SO₂ and NO_X. Meanwhile it makes the boiler scorched and the material can not burn circularly. The bed temperature not only affects the safety of whole boiler and economical operation but also the effect of boiler operation. There are many factor affects the bed temperature. The thickness of material, quality of coal, air amount, the circulation amount of material, the supply of coal, and the change of load can raise the bed temperature. The main factors are the supply of coal, air amount and the circulation amount of material. For ensuring the stability and reliability of bed temperature controlling, this article research the controlling technology of CFBB such as bed temperature measuring instrument, compensation technology, the inspection and obtaining of signal and the controlling tactics etc..The accurate measuring of bed temperature is the important link of realizing bed temperature controlling and is the premise of assuring the bed temperature can control stably and operate reliably. The bed temperature measuring is the part of bed temperature controlling system. Bed temperature signal usually is tested by bed temperature instrument which arranged in boiler bed anywhere. In accordance with the problem of normal bed temperature measuring instrument during actual operating such...