| The increasing petroleum demand of various countries all over the world has driven tanker-manufacture to larger size and super large size. In this case, the evaporation of boiler should be larger as well. However, comparatively, boilers' size is not changed so much. Under the condition of insuring both speediness as well as economy, the requirement to boiler control system becomes higher.This thesis first introduces the components and their controlling objects and targets of tank auxiliary boiler's automatic control system. This thesis also introduces the components of the boilers and their categorization and also the ignition consequence control and the major functions of safety system.This thesis makes a profound research in water level control system and steam pressure control system respectively. On the basis of the full understanding of the systems' structure and feature, the thesis analyzed the single-variable control, dual-variable control and tri-variable control, which are often used in water level control system and dual-position control, multi-position control and multi-modal PID control which are often used in steam pressure control system. In view of the control systems' advantage and disadvantage, more advanced control methods which can be used in both systems are put forward: forecast control, expert control, fuzzy control, neural network and genetic algorithms, and also the basic concepts of each control and general design of their application in both systems are introduced.After knowing the usage of PLC, the ignition consequence control and safety control program are designed, and water level control, steam pressure control process chart and program control flow chart are drawn.There are also some new implications from the thesis: PLC has been widely used in ship control and has a sound development outlook. In view of field bus and Ethernet development, the combination of PLC and field bus will have a very promising future.
|
PDF Full Text Request