Application of Turbo-Expander for Greenhouse Gas and Air Pollutant Emissions Reduction Using Exergy and Economical Analysis

The effects of greenhouse gases (GHG) on the growth of global warming and increase of GHG and air pollutant emissions for energy production have prompted the need of energy recovery, which is normally wasted in industrial plants. The present research is focused on the GHG and air pollutant emissions reduction employing pressure waste energy recovery. Break-down pressure via Joule-Thomson valve is a neat potential for waste energy recovery in gas refineries, which may also be provided using a turbo-expander instead of commercial valves. Based on this ground, an exergy analysis is carried out for Joule-Thomson valve. The results showed that the exergy loss is higher than 6.5 MW, and it is possible to recover about 1.9 MW of exergy loss. On the other hand, it was found that about 16900MWh of electrical energy can be produced by recovering the energy of waste pressure, which may lead to less consumption of the load and gas in refinery power unit. Consequently, the gas consumption reduction, 12056 ton CO2e of GHG and 54.6 ton of air pollutant emissions, is reduced annually. Economical evaluation of utilizing a turbo-expander, instead of a valve, proved that an alternative scenario is deductible and practical. Economical indexes, namely IRR and NPV, are found to be equal to 25.51 % and 929571 US$, respectively. Moreover, sensitivity analysis conducted on each specific state certified the obtained results.