Design And Theory Research Of Integration System Combining Biogas Production By Food Waste And Membrane Purification

Fossil fuels-coal, oil and gas, used as energy now are more than the total 85%. It is estimated that the world oil reserves can be mined for only forty years, gas can be exploited for more than sixty years and coal can be used more than 200 years. We can see that fossil energy sources which human beings rely on are turning out. Searching for renewable energy seems no time to delay. Furthermore, the use of fossil fuel causes CO2 emissions in our country's ranking first in the world. It is against current national requirements of the clean, sustainable and harmonious development. China is a country with large population, generates several million tons of food waste every year which should be disposed Scientifically without any pollution. Therefore, it has important practical, environmental and strategic significance to research and develop on purifying the food waste gas into natural gas, achieving waste treatment and resource science, and making up our Energy shortage,Ordinary biogas with low heat value contains a lot of CO2 and other unwanted ingredients. So it is difficult for sales and use as industrial energy and its market is limited in the rural areas. In this paper, according to the reality of China's energy shortage, the problems that food waste requires scientific treatment and difficulties that ordinary biogas is difficult to apply in the industrial field because of low heat value, we researched and discussed the method to get biogas basing on advanced membrane technology combining with other gas purification technology, theoretical integration method of biogas production and purification by large amount of food waste, how to achieve the technology systems and other related issues. Main research achievements include following points:We proposed and designed a technology system based on the technology system which integrated two-phase anaerobic fermentation to methane, biogas production using CO2 membrane separation and membrane biogas purification. Then, we designed and analyzed the theory of the main device.Basing on in-depth study and exploration of gas separation membrane materials, separation mechanism, the main characteristics, construction methods and characteristics of component construction, we developed a membrane which can efficiently remove CO2 out from biogas, and proposed technological process and experiment plan of single-stage membrane biogas purification..Through the gas purification experiments in laboratory, it showed it is feasible to construct biogas purification system by using appropriate membrane.Basing on biogas purification experiments by purification system developed by this paper, we found following conclusion:when the pressure changes between 0.2 and 0.8 MPa, with the increase of film pressure, the content of residual CO2 decreased gradually, but the content of CH4 increased gradually. When the pressure reaches 0.6 MPa, CH4 content can be 81.99%. When the pressure is increased to 0.8 MPa, CH4 content reached the highest level of 83.90%. It means that under the condition of the single-stage membrane module, if Pressure is more than 0.6MPa, we can get purified biogas which CH4 content is over 80%.Basing on analysis of major components and element distribution of food waste, we derived its approximate formula, and then estimated the potential gas production and food waste possible economic benefits by using Buswell-Mualler formula. At the sane time, we discussed the potential economic benefits of biogas production and purification. The results show that the food waste contains a large amount of biomass energy and it is meaningful and valuable to product and purify biogas by food waste. So it can be a useful complement for China's energy security.We determined the overall technology plan for two-phase anaerobic fermentation by food waste and the purification test system. We also choose the anaerobic fermentation and the fermentation tank and design fermentation tank for acid production, the Biogas fermentation tank and the mixing device and block board. At last, we design and analyze the low-pressure Biogas tank which plays a key role in the total process system..In this paper,, we provide the feasible method that food waste can be used in large-scale production of biogas and purified into valuable new energy products like natural gas, datas for referring, idears and experience of industrial development.