生物质储运过程中存在微生物生长代谢产热引起的自加热现象,可能引起生物质自燃。含水量是影响微生物生长代谢产热的重要因素。设计并搭建了120L自加热保温试验箱,以玉米秸秆为对象,在含水量20%~95%开展测试,研究含水量对其自加热特性的影响,采用温度和氧气浓度消耗速率分别表征自加热程度和微生物代谢活性。结果表明,玉米秸秆自加热达到的最高温度与峰值产热均随含水量增加先升高后降低,含水量50%时最高温度为41.1℃,含水量80%时最高峰值产热为157J/(s∙m3)。含水量低于35%时,峰值产热量随含水量变化差异较小;含水量在35%~80%时,峰值产热量与含水量呈线性关系,含水量每增加15%,峰值产热量平均增加33.43J/(s∙m3);含水量超过80%时,峰值产热量下降。微生物比生长速率与氧气消耗速率呈正比,二者随含水量增加均先升高后降低,含水量80%时氧气消耗速率达到最高值0.056%/min,微生物代谢活性最强。研究结果为分析玉米秸秆自加热特性,进而提出生物质安全储运措施提供参考。

In the process of biomass storage and transportation, there exists the phenomenon of self-heating caused by microbial growthand metabolism heat production, which may cause spontaneous combustion of biomass. Water content is an important factor affecting microbial growth, metabolism and heat production. In this paper, a 120 L self-heating insulation test chamber was designed and built. Theeffects of water content on self-heating characteristics of corn straw were studied in the range of 20%-95% water content. Temperatureand oxygen consumption rate were used to characterize the degree of self-heating and microbial metabolic activity, respectively. The results show that the maximum temperature and peak heat production of corn straw in the process of self-heating increases firstly, and thendecreases with the increase of moisture content. The maximum temperature is 41.1 ℃ under 50% moisture content, and the maximumpeak heat production is 157 J/ (s·m3) under 80% moisture content. The peak heat production of corn straw is affected by moisture content. When the water content is lower than 35%, the difference of peak heat production is small. When the water content is between 35%and 80%, the peak heat production shows a linear relationship with the water content, and the average increase of peak heat production is33.43 J/ (s·m3) when the water content increases by 15%. When the water content exceeds 80%, the peak heat production decreases.The specific growth rate of microorganisms is directly proportional to the oxygen consumption rate, and both of them increase firstly, andthen decrease with the increase of water content. The oxygen consumption rate reaches the maximum value of 0.056% / min under 80% water content, indicating the strongest metabolic activity of microorganisms. The research results provide reference for analyzing the selfheating characteristics of corn straw and proposing the safe storage and transportation measures of biomass.

0 引言

1 试验

   1.1 试验材料与预处理

   1.2 120 L自加热保温试验箱

   1.3 玉米秸秆自加热特性试验

2 结果与讨论

   2.1 试验装置保温特性及系统热平衡方程构建

   2.2 玉米秸秆自加热特性分析

   2.3 玉米秸秆内部微生物的代谢活性

3 结论