Heat Recovery Steam Generation

A Gas Turbine with Heat Recovery Steam Generation (HRSG) is a system that provides power in two ways:

  1. The Gas Turbine drives a mechanical load, for instance a generator
  2. The Turbine Exhaust Gas is used to produce steam, which may in turn drive a steam turbine coupled to another generator or other load

The HRSG system may incorporates another set of burners (often duct burners) to provide additional heat to the Turbine Exhaust Gas (TEG) and to allow for steam production in case the Gas Turbine (GT) is offline. As the exhaust fumes from a Gas Turbine normally contain sufficient oxygen (12% - 16%) for combustion of fuel in the duct burners, ambient air is only required when the GT is not in operation. The Burner Management System will therefore have to be kept fully informed of the status of the GT. This interaction between GT controller and BMS is also key to ensure that purge sequences are properly executed.

 

In terms of sequencing, an HRSG is clearly more complicated than a conventional burner. In addition to the checks executed by the BMS of a conventional duct burner, the BMS for an HRSG must separately purge the duct burner, the GT and the HRSG as a whole. The air dampers (bypass dampers, inlet damper and ambient air damper) must all be operated and proved in the proper position. The GT must be informed that conditions are safe to start, and the GT must inform the BMS that it is operating at cranking speed (for purging), that it has attained normal speed, whether it has successfully ignited, and so on. In the meantime, if the GT is taken offline or if any of the dampers loses its proved position, as indicated by limit switches, then the dampers will have be quickly re-aligned in order to safeguard minimum air flow.

A HRSG showing GT air inlet filter, bypass stack, boiler section and main stack

At Beldick we have developed our Burner Management Systems to incorporate all of the above requirements and more. We provide a full and intuitive user interface through our graphical Human-Machine Interface. We provide clear system status and alarm management including “first up” alarms. We allow for individual burners to be selected or de-selected and adjust any AFR calculations accordingly. We also make sure the BMS communicates with other (supervisory) systems in a safe and dependable way. And because we have in-depth knowledge of all the applicable standards, we can guarantee that your BMS will fly through any certification procedure that may apply.