Research Of Effect Of Secondary Air Injector On Aerodynamic Field In 1025t/h CFB Furnace

In the case of conflict of coal combustion and environment protection, the Circulating Fluidized Bed (CFB) combustion technology is largely developed in tow decades, because it is a new kind of clean coal technology with high combustion efficiency and low pollution emissions. With the large-scale development of CFB boiler, many problems appear. Secondary air injector is used to study aerodynamic field in CFB. Research about the aerodynamic field in CFB is very important to reveal the principle of gas-solid two-phase flow. Because of the complicacy of gas-solid two-phase flow, it is hard to obtain the distributions of particle concentration and velocity by experimental methods. With the rapid development of hardware and calculation technique, numerical simulation has become an important mean to study the gas-solid two-phase flow in CFB boiler.The Euler-Euler two-fluid model is used in the simulation of gas-solid two-phase in CFB boiler including the cyclone. And the standard k-εmodel is also used for the solution of the viscous item.Firstly, the dynamic characteristic of gas-solid two phase flow in modeling CFB boiler without cyclone separator is studied. Result show that the axial distribution of particle concentration is digressive as the height increasing on the whole. Particle concentration is high in central and low in the edge. The typical flow, core-annulus flow is found in results of the simulation of modeling CFB boiler. With different velocity of secondary air injector, the length of secondary air injection is different. Higher velocity secondary air injection makes deeper length of injection. Upper secondary air injector is more sensitive then lower secondary air injector. Different circulation ratio influence particle concentration in furnace. High circulation ratio makes high particle concentration; low circulation ratio makes high particle concentration. Aerodynamic field in furnace is similarity under the other same conditionSecondly, 1025t/h CFB boiler made in HBC is also study as a main object. The particle concentration distributes non-uniform from left to right at the same height. The length of secondary air injection is short. Study on the advanced version CFB, we find that the shortcoming has improvement.