| Oxy-combustion technology that is one of CCS technology with important application prospects has caused extensive research all over the world.This study selected the more economical staged pressurized oxy-combustion system to develop steady state model based on the process simulation software Aspen Plus.The all system would be analyzed and evaluated from different aspects of energy consumption analysis,pressure evaluation,integration optimization and water use analysis.At the beginning,the whole process model of the staged pressurized oxy-combustion system is established.Under the condition that overall operating pressure was increased to 12.5 bar,the gross efficiency of staged pressurized oxy-combustion system cloud reach to 45.83%(HHV)and 47.67%(LHV).In addition,the use of new generation ASU system and CPU system improved overall performance.The effectively balanced compression workload between this two units reduces the system’s corresponding energy requirements.For the DCC system used to remove SOx and NOx,a large amount of heat were recovered from the flue gas while to further improve system efficiency,while the flue gas was being purifying.Therefore,the staged pressurized oxy-combustion system achieved the net efficiency of 35.71%(HHV)or 37.15%(LHV),which is 7.41%(HHV)and 7.51%(LHV)higher than that of the atmospheric oxy-combustion system.Then based on the model of staged pressurized oxy-combustion system,the sensitivity analysis was carried out to study the influence of system operating pressure on overall performance of the staged pressurized oxy-combustion system.As operating pressures increase,more potential enthalpy can be recovered from the flue gas at higher dew points.Although ASU compression consumed more energy at higher pressures,the CPU requires less auxiliary energy.The system achieves maximum efficiency around a working pressure of 12.5 bar.In addition,based on the pinch analysis and heat integration method,10 hot and cold streams of the staged pressurized oxy-combustion system were analyzed.It was found that the maximum heat recovery value of the whole system exceeded 240 MW under the minimum temperature difference of 10 °C.In addition,the net power generation efficiency value of the system increased by 0.63%..Finally,the water use of system operation and life cycle water use of the staged oxycombustion system were analyzed.From the analysis for water consumption and water withdrawals of the six water use units,it could be seen that water was mainly used in the steam cycle cooling part.The life cycle water use of the system was evaluated from four aspects including fuel supply,infrastructure,system operation and chemical production.The life cycle water withdrawals of the staged pressurized oxy-combustion system is 3225.04 L/MWh,and the life cycle water consumption is 2165.63 L/MWh.In the whole life cycle,the proportion of water withdrawals in the operation stage of system is the largest.According to the water withdrawals,the water withdrawals in the operation stage of the system reached 87.58% of the total water withdrawals in the whole life cycle. |
