Research On Pressure Control Systems Of Ammonia Evaporation

The ammonia evaporation tank is a device used for evaporating the aqua ammonia from the wastewater in the production line of the iron oxide red. As a key equipment of the process of ammonia evaporation, the pressure control on the ammonia evaporation tank has a direct influence on the quality of the ammonia and the follow-up neutralization and oxidation reaction. The process of the ammonia evaporation is not only a procedure of production, but also a procedure of environmental protection in the whole production line of the iron oxide red. Therefore, the pressure control system of the ammonia evaporation tank can improve the product quality, reduce the labor intensity, and it has very important significance of realizing the automation of the process of the ammonia evaporation.The process of the ammonia evaporation in the production of the iron oxide red is introduced, and the characteristics of the time delay and great inertia in the process of the ammonia evaporation are also analyzed. Besides, on the basis of that the approximation model of the pressure control system of the ammonia evaporation tank is deduced from the establishment of the mechanism model and the estimation of the model parameters. In compare with the traditional PID control, the generalized predictive control can overcome the effects of all kinds of complex factors such as uncertainties, time delay and so on. This control method has a weak dependence on the model, and it is easy to control the system well. Moreover, it makes the control system have a quicker response speed and good robustness. Considered the characteristics of the time delay and inertia of the pressure control system of the ammonia evaporation tank, the generalized predictive control is proposed to improve the control performance of the ammonia pressure control system significantly. Through the simulation of the generalized predictive controller on the MATLAB platform, the results show that even in the cases of parameter time-variance and disturbance, the generalized predictive control can have a well control effects, and can be very good to eliminate the interferences on the influence of the system.At last, the general structure of the pressure control system of the ammonia evaporation tank is designed, and the basic hardware and software structure of the control system are also designed. The system realizes the real-time monitor and pressure control of the ammonia evaporation tank. And the controller realizes the continuous production of the ammonia evaporation in the production of the iron oxide red, and it also improves the production efficiency and saves the costs.