畜禽养殖场沼气工程发酵温度的确定方法

Method determinating operation temperature of biogas plant in livestock farms

为实现沼气工程运行的净产能最大化,以万头猪场配置的500m3发酵罐为分析对象,建立计算模型,计算净沼气产量,从而确定发酵温度。结果表明:发酵罐的能量产出效率指标k和能量输入效率指标η是发酵温度选择的决定性因素;在现有设计条件(k=0.55、η=0.45、发酵温度35℃)下运行,年增温所需沼气量为总沼气产量的42.4%,其中,冬季为65.2%,春季为42.1%,秋季为40.4%,夏季为22.3%,年平均净沼气产量为285.6m3/d;只有当k≥0.55和η≥0.45时,运行净能产出最大的发酵温度为35℃,当k或η值随工程运行下降,降低发酵运行温度方可获得最大净能产出;结合我国沼气工程的实际工况,建议选择30℃作为发酵运行温度,并及时对发酵设备进行维护,以确保工程的长期运行效率。

A calculation model was established to analyze and maximize the net biogas production of the large and middle scale biogas plant at the existing working condition in China,and then,a 500 m3 digester was taken as an example to investigate the optimum fermentation temperature.The results showed that the two main effects on the fermentation temperature were the biogas production efficiency of the digester（k）and the thermal efficiency of the heat exchange system thermal（η）.As the normal designing,k=0.55,η=0.45,and fermentation temperature is 35℃,the biogas used for heat loading is 42.4% of the annual biogas production,which is 65.2%in winter,42.1%in spring,40.4%in summer and in summer,the average net biogas production is 288.0 m3/d.As when k ≥0.55andη≥0.45,the optimum fermentation temperature is 35 ℃.However,as decreasing of the value korη,the optimum fermentation temperature is likely to decrease as well.Two strategies were suggested to improve the benefits of biogas production in biogas plant：operating the biogas plant at about 30 ℃in China,maintaining kandηat high values as possible.