Study On Heat Transfer Of The Pressurized Oxygen-enriched Combustion Circulating Fluidized Bed

Recently the"greenhouse effect"becomes increasingly serious and CO₂ emissions are the primary source of greenhouse gases.How to reduce and control CO₂ discharge problem has been paid highly attention by all the countries.Pressurized oxygen-enriched combustion as one of the effective control of coal combustion CO₂ emissions technology has received wide public attention because of its prominent technology and economic advantages.However, many problems waiting to be solved in the study of pressurized oxygen-enriched combustion, the heat transfer in the pressurized oxygen-enriched CFB boiler is such one urgent problem. So the research directing at the heat transfer of pressurization oxygen-enriched CFB boiler is imperative.This paper based on the existing researches and combined with real gas equations and built a model for heat transfer in a pressurized oxygen-enriched CFB boiler, which consideres flow and combustion characteristics. Using the model to analyze influence of operation parameters to heat transfer. with an example of 440t/h CFB boiler. Then it found heat transfer was reducing when the particle diameter and porosity was increasing; heat transfer was increasing when the temperature was rising, gas emission rate was decreasing with temperature rising, so heat transfer was decreasing; heat transfer was increasing when pressure was rising and the higher the pressure, the greater the growth, it showed when pressure raised to certain degree, to increase pressure was not too big effect on heat transfer. Compared with other researchers'related experimental results, it was tested the model right.Finally,the paper did preliminary conceptual design to a 440t/h CFB by the model, When the heat absorption capacity of furnace was constant at the oxy-fuel condition of 30%O₂/70%CO₂, heat-absorbing surface decreased with pressure increased, so it need to transfer external heat-absorbing surface to interior or increase external heat-transfer bed and reduce the return material temperature to keep the boiler running normally. The results of study have certain reference significance for the pressurized oxygen-enriched CFB boiler design and optimizing operation.