进料对沼气发酵温度场和产气的影响分析

Effect of Feeding on Temperature Contour and Biogas Production

稳定的发酵温度是沼气工程高效运行的关键,然而进料过程将打破发酵罐内热平衡,影响发酵产气效率。文章以30 m3发酵罐为研究对象,研究3种进料流速(0.1 m·s-1,0.2 m·s-1和0.4 m·s-1)对发酵系统热量损失和罐内发酵液温度场分布的影响规律,并选择最佳流速进行工程试验,结果表明:0.1 m·s-1的系统整体热散失最小、发酵罐内温度梯度最小,最有利于沼气发酵;工程试验表明0.1 m·s-1能有效提升日产气量,但进料温差过大,也不利于提升产气效率。建议进料前对原料进行增温预处理,并采用低负荷进料工艺。

A stable fermentation temperature is the key for the high efficiency operation of biogas project. However,the feeding process will make the digester lose the heat balance,and reduce gas production yield. In this paper,the heat loss and temperature distributions affected by different feeding flow velocity（ 0. 1 m·s^-1,0. 2 m·s^-1,0. 4 m·s^-1） were investigated adopting a 30 m^3 anaerobic digester. The best feeding flow velocity was selected for the further engineering experiment. The results showed that feeding velocity of 0. 1 m·s^-1obtained the smallest heat loss and temperature gradient,which could effectively improve the daily gas production. But the large temperature difference between the feeding and digester liquid should be avoid. It was suggested that the raw material could be preheated before feeding to the digester.