The Study On Automatic Control System Of Process Anti-Corrosion In Refining Units

This paper presents the disadvantage of present manual operation of process anti-corrosion in refining units, influence of external factor and the short life of online detectors, a novel method of continuous and automatic control is proposed. This method not only solves the problems above, but increases the rapidity, accuracy and the level of automation, avoiding some unnecessary waste of reagent. The detailed work and study are as follows:1. With the manual operation and large time delay of control system, there is an improvement on the coefficient factor of the signal single neuron PID control. According to the simulation result of matlab software, it improves the level of automation of process anti-corrosion.2. Because the pH online detector will be inaccurate after a short time, this automation scheme includes three parts of online control, judgment between online and offline control and offline control to solve this problem. As a result, this designed scheme makes the control run continuously with the wrong online detection.3. Taking the atmospheric and vacuum distillation unit for example, this paper deduces some formulas for the reason of control conditions, which gets the ranks of sulfur and acid composition. And all relevant ranks are come up with, which provide control basis for offline detecting and automatic control.4. All the programs including online control, judgment and switch between online and offline, offline control and redundancy of PLC are edited in the Siemens S7-300PLC controller. And with the Visual Basic development tool, we develop the monitoring software. Both of them could ensure the stability of the program execution of control system and reduce the cost of monitoring software comparing with the use of general configuration software.5. This paper focuses on the the atmospheric and vacuum distillation unit to design automatic control system of process anti-corrosion, and discusses whether the system could be used in other refining units. At last, some measures are taken to improve the applicability.6. The requirement on control system of reliability and safety is high in refineries, so there are redundancies and other design, which improves the safety of management and reliability of hardware and accuracy of data in the database.