Simulation Of Heat Transfer In A 1000MW Supercritical Tower Boiler

Although supercritical coal-fired power generation technology is a kind of highly-efficient,clean coal combustion technology and has been applied for many years,it faces some new problems.As the power structure changes,deep load regulation is a new problem for the supercritical boiler.Because of coal distribution and coal economy,coal variety also becomes an important problem for the supercritical boiler.Although supercritical coal-fired power generation technology has been developed for some years,there still exist some problems remained;therefore,further research is needed.The heat transfer plays a key role in the supercritical boiler.This paper studies heat transfer in a 1000 MW supercritical tower boiler.A co-simulation model is developed using Fluent and Matlab.A 3D CFD model is used to model the furnace,while a 1D boiler model is developed using Matlab.For validation,the simulated results of the BRL load case are compared with the design data;good agreement is obtained.The co-simulation model is used to study the effect of boiler load,coal species and different operational models of mills in service on heat transfer of the boiler.As the boiler load decreases,the heat absorption ratios of reheater becomes slightly lower.The heat fluxes are fitted as a function of furnace height.While the furnace height is between-2 and 54 meter,the heat flux ratio is approximately equivalent to the boiler load ratio.Coal type has a great impaction on heat transfer in the boiler.Compared with the design coal,the calculation coal 2 needs more stoichiometric air and has a lower caloric value.The heat absorption ratios of reheater and economizer for coal 2 are slightly higher,while the excess air coefficient remain unchanged.And the heat flux is lower in burner zone.The furnace height of closed pulverized coal nozzle is higher,the heat absorption ratio of reheater is slightly higher.The heat flux is slightly lower in lower part of furnace.Senior-Srinivasachar viscosity model and Cundick model are used to calculate ash deposition in the water-wall.The ash deposition is not evenly distributed.While the particle collision intensity of the region is larger,deposit thickness and deposit thermal resistance of this region is larger.The relation between them is not linearly proportional.Deposit thickness and deposit thermal resistance mainly depends on the first particle collision intensity.For front wall,back wall,left wall and right wall,the heat flux that is fitted as a function of furnace height is similar to each other.This indicates that ash deposition of these four walls is similar.