沼气发酵罐热负荷特性研究与排料余热回收装置设计

针对天津市某养殖场沼气工程,基于热平衡模型,模拟分析了沼气发酵罐热负荷特性,发现发酵罐罐体传热负荷和加热发酵料液负荷是沼气生产过程中主要负荷组成部分,而其中加热发酵料液负荷占到了沼气工程总热负荷的87.5%~90.8%,约为发酵罐罐体传热负荷的8倍。为减少发酵罐排料造成的热量损失,设计了1套沼气发酵罐排料余热回收装置,并对其余热回收效率进行模拟计算。结果表明:该装置在春季余热回收量为1 472.3~2 216.5 MJ,夏季为747.4~993.5 MJ,秋季为1 515.7~2 069.3 MJ,冬季为2 526.3~2 707.7 MJ。全年节能率波动范围在25.36%~48.46%,在冬季其节能率仍能达到30%以上,有效减少了排料的热量损失。

RESEARCH ON HEAT LOAD CHARACTERISTICS OF BIOGAS FERMENTATION TANK AND DESIGN OF WASTE HEAT RECOVERY DEVICE FOR DISCHARGE OF METHANE FERMENTATION TANK

Based on the heat balance model,the heat load characteristics of the fermentation tank were simulated and analyzed in a farm biogas project in Tianjin.Results showed that the heat transfer load of fermentation tank and the fermentation liquid heating load was the main load in biogas production process part,and heating fermentation liquid load accounted for 87.5％ ～ 90.8％ of total heating load of biogas project which was about eight times of the heat transfer load of fermentation tank.In order to reduce the heat loss caused by the discharge of fermentation tank,a set of waste heat recovery device for biogas fermentation tank was designed,and its waste heat recovery efficiency was simulated.Results showed that the device heat recovery rate was 1 472.3 ～2 216.5 MJ in spring,747.4 ～993.5 MJ in summer,1 515.7 ～2 069.3 MJ in autumn,and 2 526.3 ～ 2 707.7 MJ in winter,and annual energy saving rate was 25.36％ ～ 48.46％.In winter the energy saving rate could still reach more than 30％,effectively reducing the heat loss of the discharge.