Study On Flow And Heat Transfer Characteristics Of Synthetic Gas In Waste Heat Boiler After Dry Feed Entrained Flow Bed

Raw synthesis gas leaving the gasifier contains a considerable number of sensibleheat in IGCC system, Efficient use of waste heat boiler to recycle the heat is essential toprove the generating efficiency. Synthesis gas(CO and H2) which is high temperature,high pressure and corrosive is different from traditional exothermic agent in chemicalindustry and gas (CO2and N2)of traditional boiler. So the physical parameters of highpressure and temperature synthesis gas were researched in IGCC system, which wasused to assist the thermodynamic calculation of waste heat boiler; three-dimensionalboiler model was established and numerical simulation was calculated to research theflow and heat transfer; at the end, the boiler with variable operating conditions(pressure and atmosphere) were also be calculated by numerical simulation, and thecomparative analysis will provide basis for the design and operation of waste heat boilerin variable conditionsTaking the1×250MW IGCC demonstration projects as the example, the flow andheat transfer of synthesis gas in the waste heat boiler were researched:1) Because the synthesis gas which is high temperature (623K～1173K)and highpressure(3.1Mpa) is different from pure gas at normal pressure, the calculation ofphysical parameters is also different, reasonable physical parameters are essential forthe design and numerical simulation, so the reasonable calculation methods ofparameters were researched, such as: viscosity, thermal conductivity, specific heatcapacity, volume, density et al, at the end, the reasonable methods were found for thespecial synthesis gas.2)Thermodynamic calculation was studied by the physical parametersabove-mentioned, then radiation and convection heat transfer coefficient, the total heattransfer coefficient of waste heat boiler, as well as the percentage of heat exchange byvarious forms. Then let us have an overall understanding of the waste heat boileroperation.3)Three-dimensional physical model of convective waste heat boiler wasestablished, the suitable mathematical model were selected to assist the numericalsimulation, then the flow field, temperature field and discrete phase residence timewere analyzed. 4) In order to study the operation of the waste heat boiler at variable conditions,simulate and analyze the flow and heat transfer by changing the waste heat boiler fluegas atmosphere and the operating pressure, the changes in the waste heat boiler wereexpounded under variable conditions, Therefore simulation can be an effective means toguide the design and modification.