Research On Automatic Control Device Of Oil Boiler Auxiliary Boiler Based On PLC And Frequency Conversion Technology

Ships is truly an energy hog.With energy-saving,emission reduction being a global issue today,it is urgent that energy efficiency be improved especially in the large energy-consuming equipment.The control of Marine boiler especially used in large oil tankers has always been an important subject in the fields of marine engineering technology and automation technology.Based on one 25 T/h boiler used in tanker,focusing on analysis of characteristic of the boiler and its requirement in control,this paper proposed the use of high-performance controller and frequency converter to seek excellent performance(reliable,energy-saving,etc)by means of controlling process itself(That is,control device)in the control of the boiler water level,PID control of steam pressure,the timing control of ignition and combustion and automatic safety protection.Based on the analysis of the PLC and converter's characteristics in its functionality and performance and the boiler control requirements used in large oil tankers,This article choose S7-200 PLC and FR-740 converter to build its control system.This article focused on the configuration and distribution of PLC's input and output interface in the control system;setting of parameters and controlling mode in converter;design of software and hardware of control system.the main control circuit diagram of hardware and control procedures is also available in this paper.This article chose HITECH(Model PWS6800)touch-screen as upper monitor,designed the human-computer interface in HITECH\6.1.1.02 development environment and managed to avoid deficiencies of so-called "black box" control of the PLC control system.The control system makes it convenient and fast to set parameters without having to modify the program and greatly facilitate the debugging of the system;The dynamic parameters and its changes can be shown in the system.it can also monitor working conditions of boiler and indicate and record the faults;which make it possible to put real-time monitoring on boiler into really use.