Development of a techno-economic framework for natural gas dehydration via absorption using Tri-Ethylene Glycol: a comparative study on conventional and stripping gas dehydration processes

Abstract

BACKGROUND: To date, none of the existing techno-economic analyses on natural gas dehydration via absorption using triethylene glycol takes into consideration the profit assessment. This work addresses this shortcoming by developing a techno-economic framework that evaluates the economic feasibility of three different dehydration processes, i.e., conventional dehydration process, stripping gas dehydration process using sale gas, and stripping gas dehydration process using nitrogen, which can meet the maximum water dew point requirement set by local authorities (e.g., Malaysia) for pipeline-transported natural gas. RESULTS: Our techno-economic analyses reveal that the maximum water dew point specification of -25 °C can only be achieved by using a stripping gas dehydration process that consumes more than 260 Nm3 h-1 of sale gas or 435 Nm3 h-1 of nitrogen. In particular, the use of sale gas as stripping gas with an optimum flow rate of 260 Nm3 h-1 generates the highest annual net profit margin, of about $29 million. Such a profit margin is higher with respect to the use of nitrogen as stripping gas and the conventional dehydration process by about $1.6 million and $300 000, respectively. The minimum water dew point specification of 5 °C, on the other hand, can be achieved by all three analysed dehydration processes. CONCLUSION: The use of sale gas as stripping gas becomes more justifiable economically relative to the conventional dehydration process and the other alternative (the use of nitrogen as stripping gas) and when a low water dew point specification of -25 °C is required for natural gas. © 2018 Society of Chemical Industry.