| The field of ammonium nitrate production is filled with toxic gases, such as NH3 and NOx. These gases seriously endanger the health of workers. Automatic control system is applied in the process of ammonium nitrate production, which will increase production efficiency, protect workers safety, improve the production environment and promote the development of enterprise.An implication of process control system to a chemical Ltd. company's nitric acid and ammonium nitric production as background, analyze the main factors influence the product quality and production security. Ammonia oxidation, nitric acid neutralizes ammonia and ammonium nitric crystal processes are studied on. The mathematic prediction model is established between calcar temperature and ammonia flux. Ammonia flux ratio control is used instead of ammonia concentrate control. This method not only optimizes the control of ammonia concentrate, but also ensures calcar temperature is variated in the range of security. A dead band shift PI controller is used to handle the process nonlinearity. The neutralization reaction must happen at alkalescency circumstance. Therefore, the test module is used to measure nitric acid concentrate. This technique effectively controls the pH of neutralization and decreases the waste of ammonia. Through analyzing the ammonium crystal process and worker's experiences, crystal kettle automatic control is completed.Control system hardware consists of Siemens S7-400 redundancy controllers, CP443-1 communication processors, ET-200 distribution stations and different input/output modules. Siemens configuration software PCS7 is applied to configure hardware, define equipment address, compile control program. And PCS7 is also used to edit the monitor interface, which includes flow chart, data achievement, history trend, alarm information and form print. Ammonium nitrate process control system demonstrated excellent performance in both reducing the amount of labor intensity and improving the product quality. |
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