沼气工程进料非稳态预热工艺设计

Design of Feed Unsteady Preheating Process for Biogas Plant

针对我国沼气工程普遍存在发酵温度低,冬季产气难的问题,笔者基于所在课题组开发的新型沼液换热器和现行沼气工程间歇进料的运行模式,以华东地区50~1000 m^(3)规模的沼气工程为研究对象,建立进料温度与时间相关的非稳态预热工艺。计算表明:容积产气率为0.5~1.0 m^(3)·m^(-3)d^(-1)的沼气工程所产生沼气量均能满足全年沼液预热的能耗需求;对于50 m^(3),300 m^(3),500 m^(3),1000 m^(3)的沼气工程进料预热工艺所需单根沼液换热器数量分别为串联2根、串联6根、串联5根并联2组,串联8根并联2组;对改造后的沼气工程进行效益分析,以300 m^(3)沼气工程为例,使用新型沼液换热器后冬季(11、12、1、2、3月份)所产沼气富余量约为3539~14864 m^(3)天然气,处理COD为1239~5203 kg,效益显著。该进料预热工艺可满足华东地区沼气工程的中温发酵,实现全年的高效运行,对我国沼气工程的升级改造也具有重要意义。

The problems of low fermentation temperature and biogas production in winter commonly exist in biogas engineering in China.Based on the new biogas slurry heat exchanger developed by our research group and the current intermittent feeding mode for biogas engineering,the author took the biogas plant with 50~1000 m^(3)in East China as the research object,and established a unsteady preheating process correlated to feeding temperature and time.The results showed that the biogas production rate with 0.5~1.0 m^(3)·m^(-3)d^(-1)could meet the energy consumption demand for feed preheating in the whole year.And for the scales of 50 m^(3),300 m^(3),500 m 3 and 1000 m^(3)biogas plants,the numbers of heat exchanger pipe required for the feed preheating process were 2 pipes in series,6 pipes in series,5 pipes in series with two groups in parallel,and 8 pipes in series with two groups in parallel,respectively.The benefits of the modified biogas plant were analyzed.Taking the 300 m^(3)biogas plant as an example,after using the biogas slurry heat exchanger in winter(November,December,January,February and March),the surplus amount of biogas produced was about 3539~14864 m^(3)natural gas,and the treated COD was 1239~5203 kg,which had significant benefits.This feed preheating process could make the biogas plants in East China to run in medium temperature and achieve high-efficiency operation throughout the year.It is of great significance for upgrading biogas plants in China.