基于生命周期分析的禽畜养殖厂沼气工程性能评价

Biogas Engineering Performance Evaluation of Livestock Breeding Plant Based on Animal Life Cycle Assessment

为对比研究大型沼气工程不同沼液处理方式造成的综合性能差异,文章以某禽畜养殖厂沼气工程为例,以生命周期评价法为基础,对发酵出料直接排放及固液分离后排放两种情况进行对比,在此基础上从经济、能效和环境影响3个方面进行评价。设定情况一为发酵出料排放灌溉;情况二为固液分离后沼渣作为有机肥基质出售。结果表明,经济性方面,当沼渣售价为300元·m-3时,情况二下动态投资回收期9. 8年、自筹资金动态投资回收期3. 21年,明显优于情况一的无法在运行周期20年内收回成本、自筹资金投资回收期9. 7年;当沼渣售价低于90元·m-3时,情况一有更好的经济性。能效评价中可得情况一、情况二能量产出比分别为7. 75,17. 26,情况二较情况一单位能耗升高26. 2%,单位产能增加2. 8倍。环境影响分析结果表示环境一、情况二的综合环境影响潜力为0. 072,0. 067。综合考虑经济、能效及环境影响三方面因素,情况二是经济、节能、相对环境友好的沼气工程运行模式。

In this study,in order to compare the differences in economic,energy efficiency and environmental impact caused by different biogas slurry treatment methods in large-scale biogas projects,taking a biogas project of a livestock breeding factory as an example,and based on the life cycle assessment,two different discharge methods of biogas slurry were compared,namely： 1. discharging slurry directly（ irrigation as fertilizer）,2. discharging after solid-liquid separation（ solid residue was for sale as organic fertilizer）. The evaluation was made from three aspects： economy,energy efficiency and environmental impact. The results showed that,in aspect of economic,when the biogas solid residue was 300 yuan·m-3,the method 2 of solid separation had a dynamic investment payback time of 9. 8 years,with 3. 21 years of payback time for self-fund dynamic investment,which were obviously better than the method 1 of direct discharge for irrigation,that were 20 years and 9. 7 years,repectively. When the biogas solid residue was less than 90 yuan·m-3,the method 1 had a better economic situation. The energy efficiency evaluation showed that the energy output ratio of method 1,and method 2 were7. 75 and 17. 26 respectively. The energy consumption per unit of method 2 increased by 26. 2% comparing with method 1,and the productivity per unit increased by 2. 8 times. The results of environmental impact analysis indicated that the comprehensive environmental impact potential of method 1 and method 2 were 0. 072 and 0. 067 respectively. Taking economic,energy efficiency and environmental impact into consideration,the method 2 was more economic,energy-saving and relatively environment-friendly biogas project.