Research Of Dissolved Oxygen Control In Eumycete Fermentation Process

For many industries, fermentation is a fundamental process, and eumycete is one of the most promising fermenting microbes for food and medicine. It is much advantageous to get secondary metabolin by eumycete fermentation, and will be a important way to produce the metabolin. Dissolved Oxygen (DO) is involved in many domains of science, and it has great science and engineering significance to apply control over DO. However, DO control in microbe fermentation process is indeed left unsolved so far. Industrial fermentation requires optimized and controlled condition. This dissertation mainly deals with the control over DO in microbe fermentation process producing y-linolenic, devises a control system and builds up a DO controlling model based on Pan-bool algebra. The whole work consists of five chapters.Firstly, this paper outlines noticeable researches on microbe fermentation auto control , DO involves and DO control at present.To fermentation process, to measure and collect the data of the parameters is the premise of the control over them. Chapter 2 argues the present status of parameter measurement in fermentation, including the methods and equipment, and the restrictions fermenter applies to them.Chapter 3 primarily informs the fermentation process control system devising and the structure of the system. According to the characteristic of fermenter, we designed the control system based on single chip computer and personal computer, realizing the measurement and control over DO, pH, temperature, pressure, ventilating rate and the speed of the stirring motor. The paper details the hardware and software structure, and the working principle of the system, as well as the method to measure and control the parameters.Chapter 4 discusses the factors influencing DO in the process of fermentation in detail. Analyzing much experiment result, the paper presents a logical controlling method based on Pan-bool algebra and constructs the controlling model in allusion to the non-linear, time-varying, delaying DO control system. This theory depends on experience and logical control laws and needs no accurate mathematic model of the object, so approaches the difficulties traditional control method encounters building accurate model of the object. By simulation, the papersubsequently shows the feasibility of the method, and the result shows that this method is much advantageous over traditional methods in stability.Lastly, the work of the dissertation and the logical control method are briefly summarized.