Research And Design Of ESD In Sulfur Recovery Unit Based On PLC

Sulfur recovery unit is an important part of the exhaust gas treatment in the Refinery, which can solve the problems of exhaust gas pollution in the environment. But this unit only with the process control system is not far enough, in order to guarantee their safety and smooth running, the design of an emergency shutdown device (ESD) is essential. In this paper, an emergency shutdown device based on S7-400FH was studied and designed according to the productive and control process of the sulfur recovery unit in a petrochemical company. The major tasks are as follows:(1) Refer to the characteristics, development status, common indicators, the structures of safety level and design principles of the emergency shutdown device, the ESD system was analyzed and studied to improve its system reliability.(2) Based on the productive and control process of the sulfur recovery unit, the interlocking shutdown logics of SRU were designed, and the overall hardware configuration of a dual redundant safety interlock system on the basis of Siemens PLC was constructed.(3) The statistics of I/O points, the establishment of the CPU type, the hardware selections of I/O stations, as well as the property parameters of I/O were designed according to the relevant requirements of safety interlock in the SRU process, and the card and I/O configuration of the ESD system were completed.(4) The safety programs of the ESD system were designed to ensure that the sulfur recovery unit could interlock shutdown when the process parameters to be overrunned or the equipments appeared to be malfunctioning. Then, the automatic ignition control logic, the anti-surge control of the blower and the network communications were analyzed and researched, and provided with the design programs.(5) In this paper, the Man-machine interface of monitoring was designed by WinCC6.0configuration software, including the login/logout interface, the main menu interface, the productive process interface, the interlock logic interface, the automatic ignition control monitoring interface, the historical trends and alarm recording interface.