太阳能与发电余热复合沼气增温系统设计

Engineering design of solar and power waste energy heating system for biogas project

为了实现大中型沼气工程在北方寒冷地区的应用推广。该文针对北方寒冷气候特点,以哈尔滨双城市沼气工程为例构建了1套太阳能—发电余热中温厌氧发酵增温系统,阐述了该增温系统的设计原理,并对沼气发酵热负荷、发电机组余热回收利用率、太阳能集热装置热效率等关键参数进行了理论计算。计算得出该沼气工程全年平均每日热量的损失为6659.2 MJ,太阳能—发电余热中温厌氧发酵增温系统全年平均每日集热量为7017.6 MJ。通过对增温效果与该工程的热量损失进行对比,表明12、1、2月份系统需沼气发电机组额外提供372.2、369.4、208.3 kWh电量增温,其余月份系统可以实现发酵工程每日热量损失的补充,保证该工程的稳定运行。在8月份对示范工程的一次发酵罐体进行了增温效果测试,表明该增温系统在28 d左右可将该发酵罐内物料温度提升到中温发酵水平。该文为北方寒冷地区大中型沼气增温保温设备的配套建设提供参考。

Biogas projects have been rapidly developed in China due to their energy efficiency and environmental benefit. However, the microorganism in fermentor is inactivate and biogas production will be dramatically declined if the temperature in biogas fermentor is unstable or is too low. Sofar many biogas projects only operate stably in Southern China. It is difficult to expend the larger and medium-sized biogas projects in Northern China. Because the thermal insulation in this region cannot support the biogas fermentation. In this study, a set of heating system that composed of solar and power waste energy were tested. This technology was demonstrated for a middle temperature fermentation project in Harbin Shuangcheng city. The design principle is discussed in this paper. Some key parameters including fermentation heat load, generator heat recovery utilization rate, and thermal efficiency of solar collector unit were calculated theoretically to verify whether this heating system can meet the middle temperature condition. The results showed that averaged daily heat loss for this biogas project was 6659.2MJ during the whole year. Solar energy- power waste heating system used in intermediate temperature anaerobic fermentation can store averaged 7017.6 MJ heat per day. Because of larger temperature difference during the year in Northern China, adding heat and losing heat of the biogas project were analyzed for each month through the comparison analysis of heat supplement and loss. The biogas project needs additional 372.2, 369.4 and 208.3 kWh power from the biogas generator in December, January and February to ensure the project stable operation. In remaining months, the heating system was able to meet the middle temperature for the project. Further testing for the temperature raising effects by this heating system was conducted in August. Results showed that the fermentation raw material in primary fermentor can achieve 35℃ after 28 days’ heating,, and satisfy the middle temperature condition. With high quality solar energy resources in Northern plains, combining the solar energy and biogas power generation waste energyis bale to reduce the generator heat waste and regulate the heating system by controlling the biogas generator. The combined heating system in this biogas project can reduce the investment system. It is expected that this paper will assist designing a heating system to for the stable operation of biogas projects in Northern China.