| OCR Text |
Show cylindrical chamber, fully equipped for monitoring gas and wall temperatures . There are mUltiple ports for flame observation and for insertion of solid sampling probes. The pulverized coal is delivered down-draft to the burner with the combustion air which can be electrically preheated to temperatures up to 350°C (662°F). Gas burners on each side of the coal burner are used to heat the furnace to operating temperatures before beginning to feed the coal. The coal burner, designed and constructed by Research Division staff, is equipped with a vortex generator and four air vanes to assure good mixing and adequate residence time of the fuel-air mixture in the combustion zone. The combustion gases in the furnace are cooled by water and/or air circulating in . a cylindrical Inconel jacket around the furnace. This cooling system is equipped with temperature sensors and flow meters to control furnace quenching rates. The combustion gases leaving the furnace are further cooled by a series of air-cooled heat exchangers prior to entering the resistivity probe housing and ESP. The ESP consists of a cubic stainless steel chamber, and is equipped with two sets of interchangeable cells. One set has an 11-plate electrode with 2.5 cm (1 in) spacing, the other a 5-plate electrode with 5 cm (2 in) spacing. The design srecific collection areas ~SCA, m2/m3/s) for the two sets of cells are 39 (0.2 ft /cfm) and 17 (0.09 ft /cfm) respectively for baseline firing conditions using a high volatile US bituminous coal. The CRF instrumentation permits system temperatures, and flue gas compositions (02, C02, CO, S02 and NOx) to be monitored continuously. Gas temperatures in the furnace were measured with a suction pyrometer and flame temperatures with an optical pyrometer. Flow rates and pressures are measured by flow meters and manometers. All measuring and monitoring systems are linked to a computerized data acquisition system. Particulate mass loading in the flue gas before and after the ESP is measured with an isokinetic sampling system and particle size distribution of fly ash and wastes are measured with a cascade impactor. In-situ resistivity is measured with a point-plane resistivity probe situated in the resistivity probe housing. A detailed description of the facility and its subsystems is given in Reference 5. ADDITIVE INJECTION SYSTEM The schematic diagram of the injection system is shown in Figure 3. It consists of a positive displacement pump which pumps the additive solution from a continuously stirred tank under a pressure of 94 to 104 psig. The pump delivers the additive solution to the atomizer through which fine droplets are injected into the flue gas stream. The solution is injected into the middle of the furnace through a high pressure twin-fluid nozzle (5, 3 or 2 mm) with an internal mixing chamber, shown in Figure 4. Operating pressures range between 40 and 70 psig. The stainless steel nozzle was purchased from Turbotak Inc. The MMD of the droplets is about 17 ~m for the 5 mm nozzle, 6 ~m for the 3 mm nozzle and 3 ~m for the 2 mm nozzle. The droplet size distribution produced by the 3 mm nozzle is shown in Figure 5(6). The nozzle is equipped with a cooling jacket which protects it from extreme heat in the hot zones of the furnace. Another nozzle designed by the National Research Council of Canada (NRC) was also tested. The MMD of the droplets with this nozzle is 8.6 ~m. The NRC nozzle could be operated up to 100 |
