Pollutant emissions management in an existing plant:: The CHF3 case

Changing production patterns towards waste reduction in a globalizing world can be considered a starting point towards sustainable development. The aim of the chemical plant designer is to reduce pollutant emissions, not by cleaning the effluents but by diminishing the production of the undesirable compounds. The case study examined is focused on reducing the CHF3 emission of an existing difluorochloromethane (HCFC-22) plant by allocating the source of the problem and trying to decrease byproduct emissions by reducing their production. The effect of the operating conditions on the formation rate of both the product and the byproduct of the plant is studied and it is proved that the optimum result is accomplished simply by reducing the residence time in the fluorination reactor, that is, without the need for extra investment and/or energy consumption, a solution highly desirable from an economic point of view. The results of the study were applied to an existing plant leading to 50% reduction of the CHF3 emissions.