Efficiency Enhancement of Gas Turbines - SP1

This subproject focuses on the design of Combined Cycles Gas Turbines (CCGTs) where the exhaust heat runs a Steam Bottoming Cycle (SBC) for additional power generation and increased efficiency. For this, we need new, compact, and efficient SBC heat exchangers. Design of efficient CCGTs includes development of effective control strategies for gas turbine and CCGT operation.

Main objective:

The main objective of SP1 is to reduce the emissions related to offshore gas turbine operation. The measure with the highest emission reduction potential is to recover heat from the exhaust gas to produce electricity and/or heat in a bottoming cycle. This concept has been implemented before, but the large weight and footprint impede widespread implementation. Our focus is therefore on developing more compact and lightweight designs, possibly using other working fluids than steam.

Results 2020

  • Further development of framework for simultaneous optimisation of component design and process parameters by
    • Including full geometry description of plate heat exchangers and finned tube heat recovery heat exchangers.
    • Adding a recuperator to the cycle for improved effi ciency.
  • The heat recovery heat exchanger is a key component of a bottoming cycle, but most simulation models are 1D-models. A dynamic 2D-model was developed in 2020 to enable more detailed simulations.
  • PhD student Mohammad Ali Motamed started working in the summer. Tentative title for his thesis is "Assessment of alternative concepts for combined cycle gas turbine operation under varying loads".
  • Summer researcher Knut Andre Grytting Prestsveen successfully developed a web interface to the process optimisation model. This will be launched 2021.

Impact and innovations

  • Compact bottoming cycle designs, possibly with new working fl uids, which could enable widespread implementation.
  • New methodology for simultaneous optimisation of component specifications and process parameters.

Results 2019

This SP focuses on the design of Combined Cycles Gas Turbines (CCGTs) where the exhaust heat runs a Steam Bottoming Cycle (SBC) for additional power generation and increased efficiency. New, compact, and efficient SBC heat exchangers, designed for varying heat transfer and boiling regimes along the heat exchanger tubes, are essential. Design of efficient CCGTs includes development of effective control strategies for gas turbine and CCGT operation.

Main objective

The main objective is to reduce the emissions related to offshore gas turbine operation. Two approaches are being investigated. The first one is increasing the gas turbine's efficiency during part-load operation. The second approach is to recover heat from the exhaust gas to produce electricity and/or heat in a bottoming cycle.

This concept has been implemented before,  but the large weight and footprint impede widespread implementation. Focus is therefore one developing more compact and lightweight designs, possibly using other working fluid as steam

Main results

  • PhD position announced. Topic: "Assessment of alternative concepts for combined cycle gas turbine operation under varying loads".
  • A report about gas turbine operation and transient behavior was written as basis for future research.
  • A first working fluid screening was performed to compare possible working fluids that can  be used in a bottoming cycle (as alternative to steam).
  • The dynamic modelling and simulation of a combined cycle gas turbine was initialized in cooperation with Siemens.

Impact and innovations

  • More efficient gas turbine operation
  • Compact bottoming cycle designs, possibly with new working fluids, enabling widespread implementation
Early-stage dynamic simulation model of a combined cycle gas turbine in Dymola.