On the design of an ORC axial turbine based expander working as a mechanical driver in gas compressor stations

Lisa Branchini, Cesar Celis, Sebastian Ruiz, Rene Aguilar, Andrea De Pascale, Francesco Melino

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In this work, the feasibility of increasing the capacity of a natural gas compressor station by means of an Organic Rankine Cycle (ORC) is studied. In the proposed configuration, the ORC recovers natural gas compressor drivers' wasted heat and converts it into mechanical energy. Thus, as innovative approach, the ORC generated mechanical power will be used to drag an additional gas compressor. A case study representative of a medium-size on-shore facility is taken as reference. The mechanical drivers' arrangement is composed of four recuperated GTs of PGT5 R type (three units continuously operating and one used as back-up) and two smaller engines of Solar Saturn 20 type. Assuming the actual operation of the station, the addition of an ORC, as bottomer cycle, is designed to recover the exhaust heat from the three PGT5 R running units. According to the Authors' preliminary investigations and state of the art MW-size parameters, a regenerative sub-critical ORC cycle is selected. Therminol 66 and Hexamethyldisiloxane (MM) are chosen as intermediate and working fluids, respectively. The design ORC key cycle parameters are identified: about 2700 hp (2 MW) of capacity could be added to drive a compressor. For a comprehensive investigation, ORC off-design operating range is explored too assuming one out of three topper cycle units out of service. Since a direct coupling of the ORC driver and the gas compressor is expected, thus excluding the use of gearboxes to avoid losses, an ORC axial turbine based expander is designed that accommodates variable speed operation. The referred design includes mean-line calculations and three-dimensional computational fluid dynamics (CFD) based numerical simulations at design and off design point conditions.

Original languageEnglish
Title of host publicationIndustrial and Cogeneration; Manufacturing Materials and Metallurgy
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791885000
DOIs
StatePublished - 2021
EventASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition, GT 2021 - Virtual, Online
Duration: 7 Jun 202111 Jun 2021

Publication series

NameProceedings of the ASME Turbo Expo
Volume7

Conference

ConferenceASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition, GT 2021
CityVirtual, Online
Period7/06/2111/06/21

Keywords

  • Axial turbine
  • CFD modelling
  • Mechanical driver
  • Natural gas compressor station
  • Organic rankine cycle
  • Preliminary design
  • Waste heat recovery

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