太阳能与发电余热复合增温沼气工程的热电联供系统性能研究

发布时间：2018-07-04 10:20

  本文选题：可再生能源 + 恒温厌氧发酵　； 参考：《兰州理工大学》2017年硕士论文

【摘要】：甘肃省兰州市花庄镇甘肃荷斯坦奶牛繁育中心—中荷沼气工程热电联供系统应用沼气内燃机发电的同时对发酵塔、储气罐和进料进行增温保温。但内燃机运行中所产生的余热不能满足对原料预热以及维持发酵塔中温恒温发酵。为保证该沼气工程的产气稳定,解决因环境温度低而造成发酵塔内温度跨度较大的问题。文中通过构建一套太阳能与发电余热的增温保温系统,保证发酵塔在不同季节均能维持恒温厌氧发酵。阐述了系统的原理,并对系统各部分的热量进行理论计算。改进后的系统应用有机朗肯循环对烟气余热进行回收,使系统的总效率提高,主要的研究内容与结果如下:(1)对原有的沼气工程进行全面分析,得出沼气工程的主要散热部分为发酵塔和储气罐,需热部分为进料。其中散热损失占总需热量的5.9%-15.8%,进料需热量占总需热量的84.2%-94.1%。该沼气工程现阶段仅依靠内燃机发电余热回收系统在寒冷季节无法提供系统所需热量,内燃机余热仅可保证发酵塔在夏天维持37℃左右发酵。其它季节,余热回收系统热量无法满足系统在适宜的温度下发酵。(2)对该工程进行改造,新系统中增加太阳能对原料进行增温,其余热量用于发酵塔和储气罐进行保温。结果表明,该沼气工程需热量7531.9 MJ·d-1,太阳能与发电余热系统供热量7623.4 MJ·d-1,可使发酵塔夏季和其他季节分别维持在52℃和37℃恒温发酵,完全满足该工程的热量需求。所需太阳能集热面积为256m2,鲜牛粪总固体质量分数为27.5%,进料量为40 m3·d-1,将鲜牛粪稀释到总固体质量分数为8%时,所需水量为28.4 m3。兰州1月份自来水平均温度0.5℃,太阳能集热器出口的水温为50℃,此时所需太阳能循环水3.6 m3,自来水为24.8 m3。(3)基于“温度、品位对口,能量梯级利用”的原则,文中利用有机朗肯循环对低温烟气余热进行回收利用。利用Aspen plus软件对余热回收部分进行模拟研究,分析基本的有机朗肯循环,得出其发电效率和?效率分别为8.17%和54.16%;进行乏气回热改进后,得发电效率和?效率分别为9.42%和62.61%。回热系统相比基本的有机朗肯循环发电效率和?效率分别增长1.25%和8.45%。(4)利用太阳能与发电余热系统不仅能够为沼气工程提供充足的热量,同时对烟气运用有机朗肯循环,使系统的能源利用效率显著提高。本文创新点:(1)提出利用太阳能和生物质能驱动的、以内燃机为核心的热电联供系统,以此来解决西北大中型沼气工程寒冷季节“病态”运行状态。(2)基于“温度、品位对口,能量梯级利用”的原则,文章应用有机朗肯循环对内燃机中低温烟气的余热进行回收利用,使得整个系统的能源利用效率显著提高。
[Abstract]:The heat and electricity co-supply system of Gansu Holstein Cow breeding Center, Huazhuang Town, Lanzhou City, Gansu Province, is used to generate electricity from biogas internal combustion engine while the fermenting tower, gas storage tank and feed material are heated and insulated by using biogas internal-combustion engine. However, the residual heat generated in the operation of internal combustion engine can not meet the preheating of raw materials and the maintenance of fermentation tower temperature constant temperature fermentation. In order to ensure the gas production stability of the biogas project, the problem of large temperature span in the fermentation tower caused by low ambient temperature was solved. In this paper, a set of heating and heat preservation system based on solar energy and waste heat of power generation is constructed to ensure that the fermentation tower can maintain constant temperature anaerobic fermentation in different seasons. The principle of the system is expounded, and the heat of each part of the system is calculated theoretically. The improved system uses organic Rankine cycle to recover the waste heat from flue gas, so as to improve the overall efficiency of the system. The main research contents and results are as follows: (1) the original biogas project is comprehensively analyzed. The main heat dissipation part of biogas engineering is fermentation tower and gas storage tank, and the heat requirement part is feed material. The loss of heat dissipation accounts for 5.9- 15.8of the total required heat, and the heat required for feed accounts for 84.2- 94.1 of the total heat required. At this stage, the biogas project can not provide the heat needed by the system only in the cold season depending on the waste heat recovery system of internal combustion engine. The residual heat of the engine can only ensure that the fermentation tower can be fermented at about 37 鈩，

本文编号：2095751