Author(s)

D.P. CLOS, G. SKAUGEN, M. MAZETTI & D. ROHDE

Abstract

Steam cycles are a mature technology that has been used for many decades to produce power from heat. Novel expanders that can expand in the two-phase region have been developed for years but only recently have achieved a level of maturity that makes them commercially interesting.

In this study wet and dry steam cycles recovering heat from gas turbines in offshore industry are compared in a thermodynamic basis. Three different cycle configurations are studied in three scenarios with different combinations of power and heat demand. Every case is optimized with and without restrictions for two-phase steam expansion.

It is shown that wet expansion cycles can achieve higher steam pressures which increase steam cycle efficiency. Steam cycle power increase has been found to be large for single expansion cases (20%) due to the low pressures that can be achieved by the dry cycles.

Optimization of two-stage wet expansion does not produce significant improvements and in some cases results are equivalent to single stage wet expansion cycles.

Energy savings and CO₂ emissions reduction when comparing with the reference cases without steam cycle installation are found to be in the range of 17%–26%.

Keywords

offshore industry, steam cycles, wet expansion