Waste Gas Incineration Boiler System Design And Application Of Soft Redundant Control System

In the production process of petrochemical products, a mass of toxic and harmful gases are directly discharged into the atmosphere which will seriously pollute the environment and destroy the ecological balance. Currently the best treatment of the exhaust gases is the incineration. The ethylene glycol production line in Shanghai Petrochemical Company whose annual output is 605 thousand tons could release the waste gas mixture of CH4, C2H6, CH3CHO and the Formaldehyde. To protect the atmosphere, these substances need to be treated by burning in an incinerator before being release into the atmosphere. Therefore, the factory has invested in developing the waste incinerator for the ethylene glycol equipments. As an important part of the project, the main task of this paper is to design a set of thermal incinerator exhaust gas monitoring system with installation and debugging processes. This work commenced on the basis of the designs of consolidated incinerator furnace structure, burner and air distribution piping system, layout structure of waste heat boiler heating surface, and combined with many years of engineering practice in the design, development, debug, installation, maintenance of the thermal control system. The domestic and international researches for the design and application in the field of pyrology have been referenced.The hardware proportion of incinerator thermal control system generally composes of host computer and lower computer. The host computers are two special PC suiting industrial application which are engineer station and operator station separately. The Siemens s7-300 series programmable logic controller (PLC) is employed as the lower computer. The development of host computer control software is based on WinCC configuration software from Siemens, and the whole control system consists of four modules: Quantization of Engineering Data, Human-machine Interface, PID Control Loop, and System Security Management etc. The programming of lower computer utilizes the STEP7 toolkit provide together with the PLC, which implements the following functions: Data Acquisition/Conversion, Task Distribution, Production Process Control, and Interlocking Logic Management etc.The communication lines between host computers and lower computers employ the Ethernet connection. A lower computer is provided with two sets of CPU module to ensure the reliability of the incineration system. Taking into account the cost performance of the control system, there are some certain redundancy functions sharing between the two CPU systems which perform data exchange and backup via PROFIBUS-DP protocol between the primary and standby systems. The parameters of the instruments involved in the two ET200M distributed IO workstations in the redundant system.The research and design works included in this paper should provide useful help to the global engineers engaging in the monitoring system design for waste gas incineration.