Replacing a Shell and Tube Bundle with a Round Welded Plate Pack to Increase Heat Recovery in Existing Shell

Presented at 2017 Spring Conference held at Hilton Garden Inn, Milan North on 17 - 19 May 2017 by Robert Broad, GESMEX GmbH
With the low gas price pushing operating margins down, energy efficiency is becoming more and more important. However, retrofitting equipment to gas processing plants is capital expensive, requiring detailed design, long shutdown periods and many contractors on site cutting and welding. The energy required for the acid gas recovery unit stripper reboiler is a considerable amount. The rich amine/ lean amine interchanger is used to recover heat from the stripped lean amine, and preheat the rich amine before entering the column. Whilst modern plants are often built with more modern heat exchanger technology, older plants were built with nearly all shell and tube exchangers, being the accepted workhorse. In this paper, a model will be developed to show where the economic optimum is for replacing four shell and tube heat exchanger bundles, operating as amine interchangers in the AGRU, with round plate and shell plate packs. No piping modifications will be required for this, however installation costs for new units have been assumed. The optimized point can save over $1m a year in reducing the reboiler requirement be increasing the NTU from 1 to 4, with a gas price of $3/MMBtu, and a reduction of CO2 emissions by over 35,000 te a year.