The Research On Application Of Automatic Setting Ratio Of Ammonia And Air In The Temperature Control System Of Nitrate Oxidation Furnace

As an important industrial material, nitrate has been widely used in many fields, such as chemical industry, military, metallurgy, medicine and so on. Nitrate plays an very important role in the development of national economy. At present the production of nitrate in China is the biggest in the world. But compared with the developed countries, the production methods of nitrate is relatively backward. While paying attention to increase production, we lack process research on optimization. The production efficiency of nitrate is not high, resulting in the waste of raw material and the environment pollution. So the significance of the research in nitrate production method is very important.In the process of nitrate production, the most important is to control the temperature of the oxidation furnace, for the temperature of the oxidation furnace directly affecting the production efficiency of nitrate. The temperature of the oxidation furnace is mainly influenced by the ratio and the load, and it is also affected by the interference of the pressure and the preheating temperature change of the mixed gas. How to stabilize the temperature of the oxidation furnace through the regulation of ratio and ammonia flow has become the main content of this paper.In this paper, combining the advantages of the traditional ratio control scheme and the intelligent control, the author put forward a new method and then give the process of the control system design and simulation. The main research content is as follows:(1) Summarize the production methods of nitrate, and review the development of the ratio control method in the application research of the nitrate industry. To the shortage of traditional ratio control, puts forward the key points for the temperature control in the production of nitrate oxidation furnace.(2) Introduce the process and the characteristics of the nitrate production, then analysis the advantageous conditions in the reaction and optimize the process parameters.(3) Analysis the double closed loop ratio control system and the variable ratio control system and combine the advantages of two kinds of control system, then apply fuzzy control in the dynamic correction of ratio. Rules are made by the experienced experts, then design a fuzzy ratio correction unit to correct the real-time ratio. At the same time, the Smith predictive control is applied to the temperature hysteresis compensation in order to reduce the influence of time delay. The method that is based on Smith-Fuzzy control is proposed.(4) Apply the feed-forward control system to the control of oxygen content in the absorption tower of nitrate. The changes of ammonia flow is used as the feed-forward signal of the air to guarantee nitrate absorption efficiency in the optimum range.(5) Sum up the regulation rules of the correction unit, then design the fuzzy of the correction unit and Smith predictor. Establish mathematical model and do simulation experiment to get the dynamic and steady state performance parameters of the new control method. Experimental results show that the new control method has a better performance than the current methods.