Numerical Simulation Of The Fluid Flow And The Combustion Characteristics In A Horizontal Circulating Fluidized Bed Boiler

In recent years,it can be regarded as a higher efficiency and more environment-friendly for the circulating fluidized bed boiler(CFBB),and people pay more attention to it.But the traditional CFBB can't apply to many of small capacity industrial boilers in our country.With regard to this,it is important to develop the Horizontal circulating fluidized bed boiler(HCFBB) which can save more coal resource and reduce emissions.In this dissertation,an overall combustion model was developed for horizontal circulating fluidized bed boiler.Characteristics of gas-solid fluid,heat transfer and combustion in the HCFBB which capacity is 7MW are investigated numerically with this overall model.Characteristics of gas-solid fluid is investigated based on the two-fluid model and (?)theory of granular flow.Non-uniform distributions of vertical and lateral solid concentration,pressure in the HCFBB and local distribution of velocity are founded.It is certified that it has core-annulus structure in the HCFBB.With adjustment of first-air, solids concentration,pressure in the HCFFB are investigated and author can analysize the characteristics of gas-solid fluid in the HCFBB under different circulating rate. Pressure and solids concentration in the HCFBB varies with primary air:when primary air is increased,pressure drop will decrease,and solids concentration also will be weaken.Circulating rate has strong influence on the characteristics of gas-solid fluid in the HCFBB.In the dense zone,solids concentration will increase with increment of circulating rate.In the dilue zone,solids concentration will decrease with reduction of circulating rate.In a word,when circulating rate increases,circulation of coal feeding will increase,and solids concentration also will be denser.Under combustion condition,distribution of CO,CO₂,O₂,carbon,tempreture in the HCFBB are founded and characteristics of gas-solid fluid is investigated.Some results are compared with the experiments quantitatively.Under different condition,author can analysize the the overall combustion behavior in the HCFBB by adjusting the ratio of first-air and second-air.Moreover,it is investigated under different coal feeding.When coal feeding is fixed,and ratio of primary air and auxiliary air is reduced,tempreture in HCFBB will be heating up,vice versa.When ratio of primary and auxiliary air is fixed,and coal feeding is reduced or increased,then tempreture in the HCFBB will vary after coal feeding.