Operational experience with a closed final-cooling cycle for coke oven gas

摘要

The closed final-cooling cycle, designed by the State Scientific-Research and Design Institute of the Coke Industry to Markokhim specifications, went into operation in February 2003. The cycle includes: four final gas-cooling units (Fig. 1) with horizontal pipes (cooling surface 2900 m~2); two water-tar emulsion collectors (volume 50 m~3); two emulsion-supply pumps (productivity 125 m~3/hr; 50-mhead); two A4-450kh-6U3 pumps supplying recycled industrial-grade water (productivity 1800m~3/hr; 80-mhead). The basic system is shown in Fig. 2. Following the sulfate department, the coke oven gas is sent in two streams to the cooling units 1. Recycled industrial-grade water is used to cool the gas. The water passes through pipes between which the coke oven gas flows. To remove naphthalene deposits, the space between the cooling pipes is continuously irrigated with water-tar emulsion (25 m~3/hr per cooling unit). The approximate water/tar ratio in the emulsion is 2-3:1. This ratio is regulatedClosing the final-cooling cycle for coke oven gas by means of gas-cooling units with horizontal pipes ensures that the temperature conditions and removal of naphthalene comply with the Operational Rules. Closing the cycle does not result in ballast-salt accumulation in the absorbing oil. When using units based on horizontal pipes for the final cooling of coke oven gas, the water consumption in gas cooling is 2.5 times that for direct-action units. Closing the final-cooling cycle markedly reduces atmospheric emissions. Thus, the missions of benzene, hydrogen cyanide, naphthalene, and phenol in 2003 were 192.1, 171.52, 45.7, and 38.6 tons, respectively, corresponding to reduction by 76 percent, 88 percent, 81 percent, and 81 percent with respect to 2002.