Commissioning and Operation of an Inventory Management System

The DOE STEP 10 MWe Pilot Scale sCO2 Power Plant encompasses several pieces of turbomachinery that utilize dry gas seals to contain the process fluid. The system also has a large piping loop and multiple heat exchangers making it a large volume to fill with CO2. The plant requires an inventory management system (IMS) in order to supply the dry gas seal systems, fill the process volume, and allow for the system to change load while operating. The size of this system is important to have the ability to support the operation of the plant. In order to allow the plant to change load quickly, the pressure of the IMS needs to stay between the low pressure of the compressor suction and the high pressure of the compressor discharge. This allows the natural pressure differential to drive flow in and out of the IMS as the plant changes load. The major factor in changing load is the mass flow through the system. With CO2 near the critical point, the temperature of the tanks will be an important part of the design selection of the IMS volume required. In order to supply the dry gas seal systems when the machinery is stopped, there also needs to be a system to increase the pressure and drive flow to the dry gas seals. This paper will discuss the commissioning and operation of the IMS system in the STEP power plant.