Heat exchanger application for environmental problem-reducing in flare systems of an oil refinery and a petrochemical plant: Two case studies

In this work, two common problems for refineries and petrochemical plants were investigated, which includes burning of unwanted components in flare systems. Although some heavy components are separated in knock out drums of flare networks, separated liquids or non-separated heavy pollutants cause significant environmental problems. In the domestic refinery, the separated liquids form slops which should be treated in the waste water plant of the refinery. However, the non-separated hydrocarbons generate droplet emissions in the domestic ethylene plant site. To handle mentioned problems, the slops and droplets were analyzed, and the concerned units were simulated. Two heat exchangers were designed to reduce the water carry-over from the waste gas stream of refinery and condense the heavier pollutants of ethylene plant before flaring. The optimum condition of the heat exchangers is obtained by sensitivity analysis and economical optimization. Furthermore, the environmental benefit and cost of the new systems were investigated. The results approved the dramatic impact of the heat exchanger application on reducing the environmental problems of the flare systems. The designed heat exchanger condenses over 60 percent of water from the vapor phase and makes it suitable for introducing to the incinerator. Moreover, preventing the emission of 168 kg/h of droplets is possible by applying the heat exchanger for the domestic ethylene plant.