The Design Of The Kang-stove Household Biogas Digester Of The Cold Area And The Technical Economic Assessment To It

Searching for a solution that could deal with the energy crisis and the environmental pollution has become an urge, since the two issues have begun to block the human development. The idea of low carbon economy has been accepted and the nations are emphasizing on the biomass energy. Being one of the biomass energy, biogas has a long history. The usage of biogas is an effective approach to solving the two problems. It can not only provide the production and living of human being with clean energy, but also ease the resulting pressure on fossil energy. At the mean time, this approach takes full advantage of the industrial and agricultural waste, which improves the ecological environment and is favorable for the achievement of sustainable development.Nowadays, the biogas technology tends to mature.There are plenty of feedstocks for the biogas fermentation in our country. Domestic biogas in the country develops so fast; however, there exist a series of problems still. Temperature is an important factor to keep normal operation of domestic biogas system in the cold rural area. Thus, the key part in popularization of domestic biogas in cold area is how to achieve the heat insulation and heat preservation in a practical and economical way. In the present study, the Kang-stove biogas system is designed by combining a Kang-stove system with the domestic biogas system. The Kang-stove system is the one commonly used in cold area. A U-shaped hot smoke channel is built inside the biogas digester,and the double membrane for heating insulation is built outside the pool. This configuration could use the waste heat of smoke emitted by the Kang-stove for the heat up and heat preservation. The use efficiency is thus improved.Thermal balance calculation has been conducted for the Kang-stove biogas system, taking a 10 square metre biogas digester as an example. The results show that an average of 17 ℃ higher temperature for the fermention material and liquid could be provided by the waste heat of hot smoke emitted by the Kang-stove everyday. Thus, the requirements for normal operation of domestic biogas system in cold area can be satisfied.The evaluation of the heat up and heat preservation of the the Kang-stove biogas system has been made. For a digester of fixed size, the higher the use efficiency of the waste heat is, the better the effects of heating up and thermal insulation are. Under the same use efficiency, different heating effect can be obtained in digesters of different sizes. There is room for the improvement of the temperature of the fermention material and liquid. Under the same use efficiency, the smaller the size is, the better the effect of heating is. All can ensure the normal operation of the household biogas digester of the cold region.The technical evaluation has been made on the Kang-stove biogas system. The lower using rate of the waste gas heat,the greater heating insulation potential to the same volume biogas digester,under the premise of raising the same temperature.The results show that the heat and preservation potential of the U-shaped hot smoke channel is bigger than the double-membrane’s.Thus,the U-shaped hot smoke channel has better technology popularization value.Economical evaluation has been made on the Kang-stove biogas system.The contrast is the solar assisted heat household biogas system,with the period of cost recovery of the heat insulation facilities as the evaluation index. The results show that the period of cost recovery of the U-shaped hot smoke channel is much shorter than the contrasts. Thus, the Kang-stove hot smoke channel biogas system gets a proper promotional value.The present design of the Kang-stove hot smoke channel biogas system provides a reference for ensuring the normal operation of domestic biogas system in the cold rural area.