Optimization Design Of Heat Exchanger For Wastewater Treatment In Livestock Farm

As global economy develops, energy consumption increases dramatically. Growing energy demands caused serious environmental problems. Efficient organization of heat swap between cold and hot substances is the key to improve the entire process equipments from aspect of Economics. Relative to normal temperature anaerobic process, moderate temperature anaerobic fermentation process is faster, the decomposition of organic matter is more thoroughly, and productivity of biogas is higher. So it has broad application foreground in wastewater treatment. But the main limiting factor for it to be used in the wastewater treatment is comparatively high cost for energy of heating wastewater. At the same time the investment of wastewater heating equipments is also an obstacle to its application. Therefore reducing fuel consumption, especially external input fuel consumption, is very important for wastewater treatment in livestock farm.The great energy input hampered moderate temperature anaerobic technology to be used in livestock and poultry environmental engineering, particularly in small and medium-sized livestock and wastewater treatment process. This results in poor effect of wastewater treatment in many small and medium-sized livestock farm, low capacity of anaerobic fermentation, low output of biogas. And this also makes most of livestock farm biogas projects don't really play good functions of decomposing organic wastewater and producing renewable energy. This article proposed that the temperature of anaerobic fermentation can be increased by burning biogas (which is from anaerobic fermentation), heating fresh water directly (which can be recycled), and then warming wastewater through a heat exchanger. Such system can maintain wastewater in moderate temperature anaerobic fermentation, promote decomposing organic wastewater and increase production of biogas. Thus wastewater treatment and biogas engineering could be combined together tightly. The key of this system is the energy that is needed for heating wastewater and is not from external but from internal biogas, i.e. from the system itself. Let biogas energy make up of a friendly and interactional circulation in the system. Therefore, In this system, heat exchanger is of the essence and dose be taken as researching object of this article.The result of the research indicates that this heat exchanger at a certain climate conditions has good usability. In Chongqing's climate, it can implement its own energy supply to ensure wastewater treatment in moderate temperature anaerobic fermentation condition. The design of this heating system is good and adjustable, the process of anaerobic fermentation is steady-going, and the goal of wastewater moderate temperature anaerobic fermentation can be reached.The innovations of this article include:â‘ designed a special structure of heat exchanger, which is simple, easy for make, difficult to be clogged, easy to be cleaned, and has comparatively high efficiency of heat exchange.â‘¡used FLUENT finite element analysis for the heat exchanger, and compared with theoretical design, so the reliability of the system is increased.â‘¢optimized the structures of wastewater heating system according to the results of simulation to this special heat exchanger. These are reinforcing wastewater flow, pumping wastewater from the middle of heating pond and preserving heat with plastic-film cover.