Abstract:

For a large-scale biogas project in Heilongjiang province, based on finite element model of steady-state thermal balance, the total daily mean heat loss of a digester was analyzed under the condition of the lowest mean temperature. Results show that the daily mean temperature reduction of the fermentative materials is less than 1 °C. The proportion of heat loss in different part of the digester is also obtained. According to the results, the digester structure and insulating system for this large-scale biogas project was designed. The heating system was optimized by replacing the heat exchanger, which was located between the acidification digester and biogas digester, with general heating circular pipeline. Thus, the incrustation and rust leakage of the pipeline could be avoided and the energy consumption was reduced. The temperature of the heating material was adjusted according to daily mean temperature drop of the fermentative material in the digester to make the temperature of the mixed fermentative material be up to 35 °C. The key parameters of the heating material for external heating of digester were investigated. Our study can provide reference for the design and optimization of the heating system of large-scale biogas project in northeast China.

Key words: environment engineering, energy-saving technology, optimization analysis, insulating and heating system, biogas