柔性顶膜车库式干发酵装置运行参数优化

Operation parameter optimization of dry fermentation equipment with garage style based on flexible roof membrane

针对湿发酵工艺存在需水量大、沼液处理成本高、发酵原料单一、发酵浓度小、单位容积产气率低等不足,研究一种新型干法厌氧发酵工艺,并对干发酵工艺条件进行优化研究,旨在为干发酵沼气工程提供发酵原料最佳配比、沼液传质传热最佳效果、发酵原料最大降解率、单位容积产气率最高、沼气工程运行时间最短、成本最低等工艺参数,为当前国内干发酵沼气工程的健康、稳定运行提供一定的科学依据。该文应用设计的柔性顶膜车库式干发酵装置,以秸秆、牛粪混合物为发酵原料,进行了厌氧干发酵生产试验。研究了物料配比、发酵温度、沼液喷淋次数、发酵时间四因素对产气量和原料降解率的影响,通过L9(34)正交试验设计,对运行工艺进行优化,并与湿发酵方式进行了比较。结果表明:该装置的最佳运行工艺参数为:物料配比牛粪∶秸秆为4∶1、发酵温度35℃、沼液每天喷淋2次、发酵时间35 d。此时容积产气率为0.63m3/(m3·d)、CH4体积分数为65%、原料降解率为45%,容积产气率和原料降解率均高于湿法厌氧发酵方式。该厌氧发酵工艺克服了湿法厌氧发酵的不足,为厌氧干发酵规模化生产提供参考。

China produces the biggest amount of agricultural solid waste in the world. The annual production of agricultural solid waste is approximately 40 billion tons, of which 30 billion tons is livestock and poultry manure, 7 billion tons is crop straw, 1.5 billion tons is vegetable waste, and 2.5 billion tons is garbage and human waste. The waste is not only valuable resources, but also a major source of pollution if it has been discharged into environment without proper treatment. Nowadays as the fossil energy has been gradually dried up, the large-scale application of dry fermentation biogas technology is one of the solution to energy shortage, environmental pollution and the demand for more effective disposal of crop straw, livestock manure and garbages. The research of dry fermentation biogas technology has become a popular project in China. Bigger water demand in wet fermentation process, higher cost in biogas slurry processing, single fermentation material, low fermentation density, and low unit volume gas production are the disadvantage of traditional fermentation method. To solve these problems, this paper suggested a dry fermentation process, and the dry fermentation technology optimization condition were studied. The experiment of anaerobic dry fermentation using the garage style with flexible roof membrane was tried with setting mixture of straw and cattle manure as raw materials. The methane production and material degradation rate using different material ratio, fermentation temperature, biogas slurry spraying times, fermentation time were investigated. Working process was optimized by L9（34） orthogonal experimental design. Compared with wet fermentation, the experimental results showed that the optimal working process parameters of the device were material ratio 4：1, fermentation temperature 35℃, biogas slurry spraying times two times per day, fermentation time 35 days. The volume fraction of CH4 was 65%, the volumetric gas production rate was 0.63m3/（m3·d） and the material degradation rate reached 45% under the optimum condition . This results were better than those using wet fermentation methods. The insufficiency of the wet fermentation technology could be overcome by dry fermentation technology, which provide the reference for the scale anaerobic dry fermentation production.