Research On Natural Gas Utilization Based On Chemical Chain Technology

Natural gas has been widely recognized all over the world because of its clean and low-carbon characteristics.The consumption of natural gas will continue to rise in the next thirty years.At present,natural gas is mainly used for methanol production,ammonia synthesis,acetylene production,hydrogen production,electricity generation,oil making and so on.Hydrogen is the cleanest energy in the world because of its clean and high calorific value.Electricity is an indispensable energy in the "electrical age".In addition,the lack of oil leading high dependence of foreign.Therefore,taking natural gas as raw material,hydrogen,electricity and oil as the target products,has became the research focus of natural gas utilization.Natural gas is mainly used by burning way.Chemical looping technology is a new type of combustion technology,which can effectively improve energy utilization and reduce environmental pollution compared with traditional combustion.Taking natural gas as raw material,combined with the characteristics of the combined production system and the advantages of chemical looping technology,this paper puts forward four different processes to study the way of natural gas utilization,represently,conventional natural gas steam reforming for hydrogen and power cogeneration technology(process Ⅰ),based on chemical looping technology of natural gas for power generation(process Ⅱ),based on chemical looping technology of natural gas for hydrogen and power cogeneration(process Ⅲ),based on chemical looping technology of natural gas for hydrogen,power and oil cogeneration(processⅣ).Then the comparative study of different processes was done.The software of Aspen Plus was used to modeling and simulating the above of four processes.Some parameters were analyzed,including the mole ratio of steam to natural gas in the reforming reactor,the molar ratio of steam to natural gas in WGS,the feeding temperature and flow of the iron base oxygen carrier,the pressure of the fuel reactor,the flow of steam in the steam reactor,the separation rate of H2 into the RWGS reactor,the temperature of FT reactor,the cycle rate of unreacted gas.The thermodynamic performance of the system is obtained through sensitivity analysis and optimization of key parameters.For process Ⅰ,hydrogen production efficiency is 62.80%,the efficiency of electricity production is 3.76%,the total system energy efficiency is 66.56%,the system of exergy efficiency is 62.36%.For process Ⅱ,the efficiency of the system is 62.44%and the exergy efficiency is 59.10%.For process Ⅲ,hydrogen production efficiency is 76.48%,the efficiency of electricity production is 3.51%,the total system energy efficiency of 79.99%,exergy efficiency is 75.88%.For process Ⅳ,the hydrogen production efficiency is 32.24%,the electricity generation efficiency is 18.30%,the oil production efficiency is 24.82%,the total energy efficiency of the system is 75.36%,and the exergy efficiency is 71.56%.Comparison and analysis of the thermodynamic efficiency performance of the four processes,got the following conclusions:(1)cogeneration system(process Ⅲ)of total energy efficiency and exergy efficiency were higher than the single production system(processⅡ).(2)The efficiency of process Ⅱ is higher than IGCC for power generation,The efficiency of process Ⅱ is higher than process Ⅰ,the advantages of chemical looping technology are demonstrated.(3)Process Ⅲ and process Ⅳ were both cogeneration systems and combined chemical looping technology,both of them got high total efficiency and exergy efficiency.Process Ⅳ can not only produce some oil products,but also capture and utilize CO2,which is of positive significance for alleviating oil crisis and CO2 emission reduction.