Research On Simulation And Optimization Of Parallel Polygenration System Of Biomass Gasification-FT Liquids-power

At present,environmental pollution and resource waste caused by coal,oil and natural gas have hindered the high-quality development of green economy in China.Under the new situation,biomass has become an important energy source in today’s world because of its advantages of green,renewable and widespread distribution,and is one of the ideal substitutes for fossil fuels.As a common form of biomass energy,biomass gasification technology produces clean fuel and has good environmental benefits and resource utilization compared with direct combustion.But because the yield per unit technology is difficult to meet the requirements of efficiency,economy and environment at the same time,the poly-generation system came into being.At present,gasification raw materials（coal,biomass or coal-biomass mixture）,gasification process and system integration and evaluation index are the main contents of poly-generation system research,but there are few studies on energy utilization of poly-generation system with pure biomass gasification technology as the core.The biomass gasification technology is the largest oil of thermoelectric power plant,this topic is based on the laws of energy conversion,in accordance with the"component counterpart,hierarchical transformation、energy cascade utilization,"of the principle of energy utilization,biomass gasification as the core of the parallel type FT synthetic liquid fuel-power integrated system simulation and optimization research The chemical energy and physical energy are used step by step by cycle.First of all,each subsystem of the polygeneration system was modeled and calculated with Aspen Plus software in combination with literature data.,including gasification unit,water-gas transformation unit,the syngas purification unit,FT synthesis unit and oil refining unit,sulfur and combined cycle units,conform to the industrial production of key parameters,such as temperature,pressure,key components and energy consumption.Then,a parallel polygeneration system was designed to coupling biomass gasification-FT synthesis-IGCC to maximize the utilization of energy and achieve the optimization of benefits in all aspects.The internal material balance and energy balance of the system are calculated and evaluated by building Excel model.The influence of public works consumption on the system is considered in calculation.It studied the changes of thermal efficiency,exergic efficiency,utilization rate of C and H elements,CO₂capture rate and emission rate of sub-unit and global of poly-generation system under different split ratio（0.2,0.5,0.75,1.0）and with or without transformation,and analyzed and optimized the global energy,integration mode and key parameters of the system.In this thesis,bark biomass is used as raw material and the parallel coupling method is adopted.The results show that:Energy analysis:the thermal efficiency and exergic efficiency of FT synthetic oil-power polygeneration system of parallel biomass gasification increased as the proportion of syngas used in chemical side increased according to the shunt ratio.When the shunt ratio was 1.0,the maximum thermal efficiency and exergic efficiency were 39.36%and 54.68%respectively.For the system without transformation,33.81%and 50.62%.But its net power output is negative（-19.81MW,-32.63MW）,that is,the power output of the system cannot meet its own power loss;When the shunt ratio was 0.2,the thermal efficiency and exergic efficiency of polygeneration system were the lowest,and the conversion system was 33.39%and 48.47%.The net power output of the system without conversion increased significantly（111.59MW and 94.32MW）,while the net power output of the system without conversion increased significantly（30.45%and44.98%）.Material utilization analysis:with and without transformation,the utilization rates of C and H elements increased approximately linearly with the increase of split ratio.Due to the high CO content and the lack of conversion unit,the utilization rate of 31.40%C in the poly-generation system without transformation unit is higher than that in the poly-generation system with transformation unit,and the utilization rate of element C in the poly-generation system without transformation unit is lower than that in the poly-generation system with transformation unit,resulting in a total utilization rate of element H（30.39%）12.04%lower than that in the poly-generation system with transformation unit（42.43%）.Environment-friendly analysis:With the increase of split ratio in the polygeneration system,the C capture rate increases.When there is no transformation system,the CO₂ purified and absorbed comes from the CO₂ in the syngas,and the lack of transformation reaction makes the capture rate of C smaller than that of the transformation system.The capture rate of transformation system C is 50%,and the emission rate of C is 2.27%.The capture rate of system C without transformation is 11.4%,and the emission rate of system C is 16.7%.It can be seen that carbon emission reduction mainly depends on the degree of water and gas shift.Compared with the system without shift,the system with shift is more friendly to the environment and has greater development potential.