Correction Of Several Key Parameters For Thermal Calculation Of Oxy-fuel Combustion Boiler Based On 35MWth

Oxy-fuel combustion technology is recogni zed as one of the m ost potential CO2 capture technologies inthe world, which was extensively researched in China. Based on the first pilot scale 35 MWth oxy-fuel combustion boiler in our country, the operation data of air combustion and oxy-fuel com bustionwas compared in this paper, especially the heat absorption capacity of each h eating surface. The fouling coefficient, thermal efficient coefficient and heat utilization coef ficient were analyzed, which are regarded as th e most important coefficients in the oxy-fuel combustion thermodynamic calculation.First of all, it focused on th e study of fouling c oefficient in the oxy-fuel com bustion boiler. The results showed that when the fou ling coefficient is 0.45 in the air condition, the calculated value of the f urnace outlet fuel gas temperature is nearly 60? higher than the experimental value in the conditi on of oxy-fuel dry recycle and 25 ?higherthan in the condition of oxy-fuel wet recycle. When the fouling coef ficient is 0.53 in the oxy-fuel dry recycle and 0.49 in the oxy-fuel wet recycle, th e calculated value of fuel gas temperature is equal to the experimental value. The heat absorption capacity of the boiler in the condition of oxy-fuel dry recycleandwet recycleis respectively 30.0% a nd 30.6% higher than that in the same condition of air combustion.Then thermal effective coefficient of high temperature super-heater and low temperature super-heater was studied. The calculatedflue gas temperature in the o utlet of high temperature super-heater was 15 ? and 4 ? lower th an the exp erimental valuein oxy-fuel dry and wet recycle. The calculated flue gas temperature in the outlet of low temperature super-heater outlet was 15? and 4? lower than the experim ental value in oxy-fuel dry and wet recycle. Reducing the thermal coefficient within a certain range can make the calculated flue gas tem perature in the outlet of high tem perature super-heater equal to the experimental values in oxy-fuel condition. The heat absorp tion capacity was calculated through the corrected therm al effective coefficient of super-heater. Results indicated that the heat absorption capacity of high tem perature super-heaterin oxy-fuel dry and wet recycle was 26.6% and 14.5% lower than that in air combustion, whereas the heat absorption capacity of low temperature super-heater was 6.2% and 6% lower.Finally, the fouling coefficient of superior and inferior econ omizer was researched. Results showed that the fouling coef ficient of economizer in oxy-fuel combustion is lower than that in air atm osphere and th e corresponding heat absorption capacityin oxy-fuel combustion is higher than that in air atm osphere. There is no need to correct the heat utilization coefficient of air preheater becau se using air co mbustion value stand ard, the calculated exhaust gas temperature was equal to the experimental value.