Substitute natural gas

About: Substitute natural gas is a research topic. Over the lifetime, 1216 publications have been published within this topic receiving 23604 citations. The topic is also known as: synthetic natural gas.

Evaluation of alternative processes of CO2 methanation: Design, optimization, control, techno-economic and environmental analysis

Abstract: Converting carbon dioxide (CO2) into substitute natural gas (SNG) has received renewed interests recently. It not only realizes large scale CO2 conversion, but also provides a synthetic source for those countries lacking natural gas. This study firstly attempts to explore and evaluate alternative processes for CO2 methanation, in which four schemes (six processes overall) based on adiabatic and/or non-adiabatic fixed-bed reactors are focused. Rigorous process design, optimization, waste heat recovery, economic and environmental evaluation, and control are covered. From this work, the most promising configuration (i.e. Scheme 4B) uses only two reactors. A counter-current cooling, non-adiabatic reactor equipped with internal recycle goes first, and an adiabatic reactor follows. This process reveals great CO2 reduction potential (i.e. CO2-e: −3.338 kg/kg), as compared with other previously developed processes converting CO2 to value-added chemicals (i.e. CO2-e: −0.154 to 2.242 kg/kg). More importantly, better operability of the first reactor is indicated by the generated temperature profile. Finally, a suitable control strategy is developed for this scheme, which results in satisfactory closed-loop responses under throughput and composition disturbances. For future work, clarifying how the feed impurities influence the reaction kinetics, and developing a less expensive hydrogen source, will be recommended.

Supercritical CO2 utilization in a CO2 zero emission novel system for bio-synthetic natural gas, power and freshwater productions

Abstract: Supercritical CO2 utilization is of interest because its supercritical conditions are easily accessible. Supercritical CO2 was utilized in this study in a Brayton cycle driven by a biomass gasification for power production and preheating a humidification-dehumidification desalination system. Biomass gasification triggered a methanation reactor for production of a bio-synthetic natural gas which is a synthetic natural gas obtained from a biomass resource. This technology has a promising performance because it approximately does not have carbon dioxide emission and producing bio-synthetic natural gas from a biomass gasification using a methanation reactor is a carbon dioxide negative technology. Response surface methodology has been utilized for comprehensive investigation and multi-objective optimization of the novel tri-generation system considering power production, freshwater flow rate, and methane content in bio-synthetic natural gas as criteria and selecting biomass feed rate, steam to biomass ratio and pressure ratio of supercritical carbon dioxide Brayton cycle as variable parameters. What stands out in results of analysis of variance is the dominance of biomass feed rate in shares on outputs. Biomass feed rate of 1.2 mol/s, steam to biomass ratio of 1.5 and pressure ratio of 3.5 resulted in the optimum response variables of power production of 172.6 kW, freshwater flow rate of 778.8 kg/hr, and methane content of 50.8% in bio-synthetic natural gas.

Process for co-producing and synthetic natural gas and food-grade carbon dioxide by using calcium carbide furnace gas

Abstract: The invention discloses a process for co-producing synthetic natural gas and food-grade carbon dioxide by using calcium carbide furnace gas. The process sequentially comprises the steps that after purified calcium carbide furnace gas is pressurized and mixed with medium-pressure steam and then the obtained mixture enters a shift-converter to carry out shift-conversion, the obtained gas enters a methanation reactor to carry out methanation, and then enters a decarbonization system to remove CO2; the gas subjected to CO2 removal is dried, and then enters a methane concentration system to carry out concentration, thereby obtaining synthetic natural gas; and the removed CO2 is prepared into food-grade CO2 through a recovery unit. The decarbonization system can adopt a PSA (pressure swing adsorption) dry decarburization process, and also can adopt a wet decarburization process. The wet decarburization is implemented by removing CO2 by using a thermokalite method or MDEA washing. A CO2 recovery unit has the functions of CO2 collecting, purifying, and purification by flash distillation. The methane concentration can be implemented by concentrating methane by using a PSA method, and also can be implemented by concentrating methane through low-temperature separation. The process disclosed by the invention is a packaged technology for co-producing synthetic natural gas and food-grade carbon dioxide by using calcium carbide furnace gas, which is suitable for industrial scale applications.

Production of synthetic natural gas

Abstract: PURPOSE:To obtain a synthetic natural gas at a relatively low temperature and pressure, by subjecting a raw material containing methanol as a main component to catalytic reforming using a catalyst obtained by molding and calcining a mixture consisting of a specific ratio of nickel sesquioxide and an inorganic carrier. CONSTITUTION:Raw materials consisting of (A) nickel sesquioxide of 30-90% based on NiO, preferably (B) >=1 kind of 1-20% oxide selected from Mo, La, Zn, Cr, Ru and Li and (C) residual amount of an inorganic carrier composed of TiO2, ZrO2, SiO2, Al2O3, MgO, etc., are blended and molded and calcined at 300-500 deg.C to provide a catalyst, which is subjected to activation treatment and temperature and pressure in a reactor is maintained to 150-500 deg.C and ordinary pressure - 10kg/cm pressure respectively and a raw material containing methanol preheated as a main component and steam are passed through the catalyst in 0.5-4hr LHSV and <=1.0 steam ratio to convert the raw material to a gas rich in methane.