The EERC has numerous laboratory-, bench-, and pilot-scale systems that can be used to subject coal and other solid materials to hydrothermal treatment. The multigram extraction system is capable of treating up to 20 g at sub- and supercritical fluid conditions, including those of water. The system consists of flowing heated water through a fixed bed of solids for a given amount of time. The main components are a hydraulic pump, three electric heater systems, a reactor cell, a pressure control valve, a pressure letdown vessel, and two condensers. The unit is equipped with ten thermocouples, three pressure gauges, and two system relief valves.

The fluid is pressurized using an air-operated hydraulic pump system, which has the capability of pumping about 60 lb/hr of water at 2200 psig; however, for most of the testing with the multigram extraction system, water flow rates have been between 10 and 300 cm³/min. The pump is equipped with an internal pressure regulator to control system conditions. The water is heated through a series of two preheaters followed by a main reactor cell containing the solid material. The first preheater is a 3/4-in.-outer-diameter high-pressure cone-and-thread tubing wrapped by an 800-watt electric heater with controls. The middle heater contains coiled 1/8-in. high-pressure tubing wrapped by a 1000-watt Thermolyne muffle furnace. The heated water/steam is exposed to solid material in the reactor cell. The 40-cm³ high-pressure tubular reactor is surrounded by an 860-watt heater to maintain a consistent temperature throughout the reactor. The process water/steam is then depressurized to atmospheric conditions in a 1-gal autoclave assembly using a small metering valve specially designed by Pressure Products Industries. The process steam is cooled through a series of condensers, allowing appropriate water and gas samples to be collected for material balance information and analysis.