Study On AB ControlLogix PLC Applied In FGD Project For 2×600MW Power Plant

FGD(Flue Gas Desulfurization)is a main method which used in large coal fuel power plant to remove the SO2 in the flue gas after the boiler.In this article, the engineering applications of AB PLC used in FGD project are analyzed and studied. The main contents include:PLC hardware configuration, that the net is combined by two layers, the above layer is star type Ethernet we called monitor and control layer, the lower layer is ControlNET we called process control layer. The controller and I/O distribution plan and the system power and grounding plan also be introduced.Closed control loops such as BUF blade angle control, limestone slurry density control, limestone slurry flow control, gypsum hydrocyclone inlet pressure control, gypsum cake thickness control are introduced and analyzed. The important closed control loop such as limestone slurry flow control loop is analyzed in detail about the desulfurization efficiency and flue gas flow calculation formula, the switch procedure during field signal failure.Main interlock and sequence control requirements, such as interlock between boiler and FGD, FGD trip terms, FGD system star and stop procedures are analyzed. Specially, the start and stop sequence of flue gas system, BUF, recirculation pump and mist eliminator washing are studied in detail.Some detail charts and diagrams are given in this article. These are I/O list, closed loop diagrams, HMI(human machine interface) pictures and the process parameters alarm list.For the direct influence of main equipments and instruments to the FGD operation, a summary and analysis is given for Failure detection and alarming of the main equipments and instruments which are used in the FGD project.By the end of this article, the economic analysis is given for the signal unit of FGD in this project.Wishing this article can give some suggestions and references to the later FGD project.