After finalizing the field devices like actuator/positioner valves and safety interlock devices. Panel design will begin. Choosing logic platforms and panel components based on experience with reliability plays a big hand.
Next the drawings will be engineered taking into account the I/O count and tag naming.
After drawings have reached a milestone near completion, panel parts will need to be purchased and supplied to a panel builder with the drawings for assembly.
The layout and hardware configurations will need to meet NFPA85 code requirements and when the panel is ready, there will be a formal wiring and programming checkout before the panel is shipped to the site for installation.
Programming the control system is a complex task as well. The program will be based on two aspects of fundamental boiler control. The safety aspect and the running control aspect.
The safety aspect is the burner management system and will be compiled of all the safety interlocks discretely tied to the PLC controller. The interlocks will be programmed following NFPA85 guidelines as well and facilitate interposing relays for all outputs as well as a watchdog timer and input checking logic for all of the failsafe interlocks that function as on is a good state.
The controlling aspect is the Combustion Control System and is compiled of all of the controlling devices. After the safety system starts the boiler it will hand control to the combustion control for metering the fuel and air as well as other boiler functions like oxygen trim and drum level. If the combustion control malfunctions, it will have one failsafe interlock that will tell the safety system to shut the boiler down. Malfunctions are usually based on bad quality readings from transmitters and set point deviation for the fuel and air.
Collins Combustion Services provides industrial boiler control system related services and tuning as well as emergency repair. |
