OCR Text |
Show 6 Operation of the PDTF requires the initial pressurization of the entire vessel after the furnace has been brought up to the desired operating temperature, usually with an inert gas. During operation, the pressure of the reactor is controlled by metering the exit gas with an electronic pressure controller, balancing the outlet flow to the input of the feed gas plus any gas produced during operation. Pulverized coal, typically 8()% -200 mesh, is introduced into the reactor with a carrier (primary) gas through a water-cooled injector probe. This injector is mounted to a translating device which moves the injector in the center of the reactor tube to various heights to allow variable residence times of the feed in the reactor zone. Optional secondary gas enters the reactor at the top of the reactor tube and flows down through the tube around the injector assembly and mixes with the primary gas and feed. The coal residue and process gases travel down the reactor tube in a laminar flow regime and pass through the accelerator where they are collected by a water-cooled, nitrogen-quenched ash collection probe or a water-cooled deposition probe. Various collection devices can be attached to the outlet of the collection probe to collect the gases and solids. The process gases exiting the collection device are monitored by on -line O2, CO, and CO2 gas analyzers and by taking gas bag samples for off-line gas chromatography (GC); the remainder of the process gases are then routed out through a vent. For this project, size segregation of the residue was facilitated by using a multicyclone and final fliter assembly, which was kept at the system pressure but under a lower temperature of 150°C. A bulk filter is used to collect ash for bulk chemistry. Tests were conducted under a broad range of conditions, varying temperature, pressure, and OIC ratio. Efforts were made to ensure that the same sampling procedure was followed for all tests under all of the various conditions. Operating procedures followed the standard PDTF routine as did the sample collection. For these tests, the particulate collection probe was used. Attached to the outlet of the probe was the No.2 cyclone (3-llm size cut), then No.5 cyclone |