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冬季北方寒冷地区温度偏低,难以满足大中型沼气厌氧发酵系统对于温度的要求。为了解决该问题,针对天津地区某奶牛场沼气工程,设计了一套回收发电机余热并辅助电加热为发酵罐体供热的沼气增温控制系统,且实验确定最佳控制温度为35℃。在该系统中,罐体内部均匀布置竖直型循环加热管路,从而使料液温度分布更加均匀,热响应更加迅速,6 d左右即可将发酵罐内发酵料液提升到所需最佳温度;另外,采用罐内部温度及循环水流量的反馈调节,使料液的温度波动维持在±1℃范围内,解决了在冬季由于温度过低而导致沼气产气率偏低、甚至停滞的问题;同时,采用MATLAB软件对基于F-PID及传统PID的温度控制系统进行了仿真。对比结果表明,F-PID控制器较传统PID控制器超调量减小3℃,响应时间缩短60%,表明F-PID系统具有更高的效率、稳定性及实用价值。
Winter cold in northern temperatures is low, it is difficult to meet the medium and large biogas anaerobic fermentation system for the temperature requirements. In order to solve this problem, a set of biogas warming control system was designed to recover the waste heat of the generator and assist the heating of the fermentation tank for the biogas project of a dairy farm in Tianjin. The optimal control temperature was 35 ℃. In this system, vertical circulation heating pipes are uniformly arranged inside the tank, so that the temperature distribution of the feed liquid is more uniform and the thermal response is more rapid. The fermentation liquor in the fermentor can be lifted to the desired optimum level in about 6 d Temperature; In addition, the use of tank internal temperature and circulating water flow feedback adjustment, so that the liquid temperature fluctuations in the maintenance of ± 1 ℃ range, solved in the winter as a result of low temperature gas biogas production rate is too low, or even stagnant At the same time, MATLAB software was used to simulate the temperature control system based on F-PID and traditional PID. The comparison results show that the F-PID controller reduces the overshoot by 3 ℃ and the response time by 60% compared with the traditional PID controller, which shows that the F-PID system has higher efficiency, stability and practical value.