Optimization of process parameters for glycol unit to mitigate the emission of BTEX/VOCs

Recent developments in environmental regulations on the emissions of aromat ic compounds including benzene, toluene, ethyl benzene and xylene isomers ( BTEX) and other volatile organic compounds (VOCs) have made these emissions a major concern in the natural gas industry. In particular, one of the sou rces of emissions is glycol dehydration units. During the dehydration of na tural gas, the BTEX and VOC compounds in it are absorbed by the glycol solv ent, and subsequently emitted to the atmosphere during the thermal regenera tion of glycol. As a result, quantification and means of reduction and ulti mately elimination of these emissions is gaining importance in the industry . This problem requires careful attention during the design phase. The enviro nmental considerations mentioned above are increasingly driving the selecti on and operation of process alternatives to reduce the BTEX/VOCs emissions to the atmosphere. This paper focuses on the glycol dehydration unit for one of the onshore oi l and gas processing facilities in Abu Dhabi operated by Abu Dhabi Company for Onshore Oil Operations (ADCO). Firstly, the BTEX/VOCs emission levels v ented out to atmosphere are quantified, and a description given of the samp ling/measurement technique. Secondly, the process parameters associated wit h all major equipments in the glycol dehydration unit, i.e. the absorber, t he flash tank, and the regenerator that may lead to the reduction in BTEX/V OC emissions, are optimized. The optimization study involves building a pro cess simulation model based on actual design data/parameters provided by th e glycol unit vendor and verified by operational data.