【作者】 张翔；

【导师】 柳朝晖；

【作者基本信息】 华中科技大学 ， 热能工程， 2019， 硕士

【摘要】 富氧燃烧技术作为具有重要应用前景的CO₂捕集、封存与利用技术之一,在世界范围内引起了广泛研究。本文选取经济性上更具优势的分级增压富氧燃烧系统基于过程模拟软件Aspen Plus进行建模,从系统的能耗分析、压力评价、集成优化、水耗分析等方面对分级增压富氧燃烧系统进行评价。首先建立分级增压富氧燃烧系统全流程模型,在整体操作压力提升到12.5bar的工况下,系统的毛效率提高到45.83%（HHV）和47.67%（LHV）。此外,采用的空分系统（air separation unit,ASU）和CO₂压缩纯化系统（CO₂ compression and purification unit,CPU）改善了整体性能。对于脱除SOx和NOx采用的直接接触式冷却塔（direct contact column,DCC）装置,在净化烟气的同时回收大量热量,进一步提高系统效率。因此,分级增压富氧燃烧系统实现了35.71%（HHV）或37.15%（LHV）的净效率,相对于常压富氧燃烧系统提升了7.41%（HHV）和7.51%（LHV）。继而在分级增压富氧燃烧系统模型的基础上,进行系统操作压力对分级增压富氧燃烧系统整体性能影响的灵敏度分析。随着操作压力的增加,在更高的露点情况下烟气中可以回收更多可用的潜在焓。虽然ASU压缩在较高压力下消耗更多能量,但CPU需要较少的辅助能量。系统在12.5bar的工作压力附近可以实现最大效率。此外基于夹点分析和热集成方法分析分级增压富氧燃烧系统10条冷热物流,发现在10℃的最小温差下,全系统最大热量回收值超过240MW,系统净发电效率值增加了0.63%。最后,对分级增压富氧燃烧系统运行水耗与生命周期水耗进行分析。从六个耗水单元的取水量和耗水量分析可以看出,水的使用主要在蒸汽循环冷却部分。从燃料供应、基础设施、系统运行和化学品生产四个方面来评价系统生命周期水耗,分级增压富氧燃烧系统的生命周期取水量为3225.04 L/MWh,生命周期耗水量2165.63 L/MWh。在整个生命周期,系统运行阶段所占的比例最大,按照取水量计算系统运行阶段取水量达到整个生命周期取水量的87.58%。更多还原

【Abstract】 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.更多还原