Research On Supply Technology Of Blending Conventional Gas Into Biogas

Nowadays, the biogas industry development in China has not only achieved preliminary results in the amelioration of rural energy structure, but also brought out some social and economic benefits. But the utilization and extension of biogas have not reached a level of industrialized and large-scale development, because raw materials shortage and poor fermentation caused by different regional resources distribution and climate induce biogas industry has a disparity between the requirement and supply, even lead to biogas production is at a standstill. Therefore, the paper puts forward a new and practical approach which is worth popularizing besides temperature rising fermentation and other measures. This approach based on biogas utilization priority and gas interchangeability takes conventional gas which is reliable and easy to access as supplementary gas source and blends conventional gas into biogas to provide daily gas for residents. The approach can both make full use of renewable energy sources and guarantee the continuity and stability of gas consumption for residents.The research on interchangeability and safety in this paper can provide theoretical basis of making up gas blending scheme and controlling the gas blending ratio for the supply technology. The blending device has been designed and can be served as the tool to realizing gas blending which has been verified through numerical modeling for the supply technology. The measurement of gas stove’s combustion condition can provide terminal utilization platform for the supply technology. The main research works are as follows:① So as to guarantee the biogas’ s continuous and steady supply, the paper has adopted the scheme of blending air into natural gas to reinforce the 6T natural gas supply. And by calculating Wobbe index, combustion potential, A.G.A index and Weaver index, the interchangeability judgement is assured. Supplemented by safety computation of explosion limits, the research concludes that if air and natural gas blended evenly as the ratio of 47:53~51:49, mixture could satisfy the interchangeability safety requirements.② The structural parameters of the inspirator mixer have been figured out by means of calculated air-natural gas ratio’s upper limit and empirical data. Through the ANSYS software numerical modeling of the inspirator mixer’s working conditions, the result shows that the distribution of velocity and pressure field figured out by theoretical calculations are consistent to that by numerical modeling. The inject ratio can reach set value.③ The inspirator mixer operation characteristics experiment platform is built up which has two gas sources and equipped with the inspirator mixer. Above all, by studying the influence factors of inject ratios, the experiment concludes that: The inject ratios increase as the difference values between inject pressure and outlet pressure increase, which the outlet pressure of the inspirator mixer has greater influence on inject ratios. In order to satisfy the air-natural gas ratio by interchangeability calculation and guarantee enough incoming gas pressure, the inlet pressure value of the inspirator mixer is at least reach 0.25 MPa. Then, through the comparison between experiment data with numerical modeling data, the research finds out that the relative error between experimental data and analog data is below 10%. The designed inspirator mixer can realize the effective blending between air and natural gas.④ Through the stability experiment for gas stove’s combustion condition, the stable working curves of gas stove under different gas constitution are figured out, which shows that the blending gas that meets interchangeability requirements can burn stably in 6T natural gas stove.