连续发酵生产乙醇的过程模拟与优化研究

Simulation and Optimization of Continuous Ethanol Fermentation Process

对发酵过程进行模拟优化是降低乙醇生产成本、促进乙醇工业化生产的有效途径。考虑到乙醇发酵过程中存在的各种竞争性抑制作用，结合连续生产的全混釜模型方程，利用AspenPlus软件编写并建立了用户模型，实现了玉米清液连续发酵制乙醇过程的全流程模拟，模拟结果与工厂生产所测数据一致。同时对发酵过程进行了分析，优化了生产条件。计算结果表明，发酵罐中糖液的进料情况对结果影响较大，预发酵以及酵母回流是为了维持系统内合适的菌体浓度，需要根据实际情况调整；为了避免系统染菌，发酵过程宜采取带压操作，压力0．12--0．14MPa为佳；工厂实际生产工艺中，前3个发酵罐的热负荷较大，需要重点采取散热措施。对发酵系统进行热量优化有利于生产发酵罐的温度控制，提高产品质量。

Simulating and optimizing the ethanol fermentation process will benefit the ethanol production and decrease its cost. Using Aspen Plus software, a user model library was established by writing user programs. The simulation of the whole continuous ethanol fermentation process using the purified corn saceharification liquid as fermented medium was accomplished, and it shows that the simulation results agree well with the production data. Then the continuous ethanol fermentation process was analyzed and the production conditions were optimized. The results show that the corn saccharifieation liquid feeding amount affects the fermentation results obviously, and the arrangements of pre-fermentation and recycle of yeast in the fermentation system are used to keep a proper yeast concentration in the system which should be adjusted according to practical situation. In order to avoid the infection of the system by other bacteria, it is suitable to maintain the fermentation system at a low positive operating pressure, such as 0.12-0.14 MPa. In present fermentation process, the heat loads of the former three fermenters are a little too height, it needs to take some measures to improve it. Therefore the heat load optimization of the fermentation system was conducted to make the fermentation temperatures of fermenters under control, which will enhance the quality of the produced ethanol.