Process Intensification of Triethylene Glycol Dehydration Units with Respect to Rated Energy Consumption, Emissions and Product Quality

Natural gas is the most widespread fossil fuel nowadays, used both domestically and in industry. Its processing is highly energy and cost intensive and consists of multiple steps. The gas dehydration is an essential and irreplaceable process because water content minimization is crucial in prevention of hydrate formation, electrochemical corrosion control as well as for subsequent cryogenic processing if present. Despite its importance, the dehydration step is often designed and operated based on rules of thumb and good practice instead of a systematic approach. This makes dehydration an adequate candidate to apply a previously suggested complete and concise Process Intensification (PI) framework developed specifically for oil & gas (O& G) industry. This framework suggests the Rated Energy Consumption (REC) as the key and measurable driver for design and implementation of PI tools. This paper presents a case study on absorption dehydration using triethylene glycol (TEG). The study is based on an existing facility. First, a process model was built and used to evaluate REC of the system with three main contributors: reboiler, stripping gas and circulation pump. For a PI analysis, two key process parameters affecting the REC were identified, i.e. TEG circulation rate and stripping gas consumption. Using response optimization, it was shown that the original design point is sub-optimal with respect to REC and indirect CO2 emissions, which could be reduced by 23 and 19 % respectively, while maintaining the product water content. The outcome of this work represents an important foundation for future PI within a more complex dehydration process considering also cooling and condensation upstream of the TEG unit and adsorption as a subsequent step