Evaporative Gas Turbine Cycles
Scope
A research project was carried out at the Department concerning evaporative gas turbine cycles (EvGT). This project was a co-operation between universities, gas turbine manufacturers, utility power companies and research organizations in Sweden. The overall goal was to increase the knowledge of evaporative gas turbine cycles and to demonstrate the EvGT cycle. A Pilot Plant was erected at Lund Institute of Technology. Three different thermodynamical cycles was tested in the pilot plant; the simple, the recuperative and the evaporative cycle. The final pilot plant roughly consisted of a 600 kW gas turbine, a hydraulic brake, a recuperator, a humidification tower, an economiser and a flue gas condenser. All layout and functional analyses were made within the project.The pilot plant is, however, optimized neither for best efficiency nor for best emissions. It was only built for demonstration purposes.
Abstract
In recent years the interest for new advanced thermodynamical gas turbine cycles has increased. One of the new designs is the evaporative gas turbine cycle. A lot of effort worldwide has been put into predicting the possible efficiency, pollutants and dynamic behaviour of the evaporative gas turbine cycle, but all results so far have been affected by uncertain assumptions. Until now this cycle has not been demonstrated in a pilot plant. The purpose of this work was to identify the potential of this cycle, by erecting a pilot plant at the Lund Institute of Technology. The project was financed on a 50/50 basis from the Swedish National Energy Administration and the industrial partners.
Three different thermodynamical cycles was tested in the pilot plant: the simple, the recuperative and the evaporative cycles. The final pilot plant roughly consisted of a 600 kW gas turbine, a hydraulic brake, a recuperator, a humidification tower, an economiser and a flue gas condenser. All layout and functional analysis was made within the project. The pilot plant was, however, optimized neither for best efficiency nor for best emissions. It was only built for a demonstration purpose.
It was shown from the performance tests that the efficiency for the simple, recuperative and evaporative cycles are 22, 27 and 35% respectively, at rated power output. The NOx emissions were reduced by 90% to under 10 ppm, and the UHC and CO were not measurable when running the evaporative cycle at rated power output. It was also shown that it is possible to reach full power output from the evaporative cycle in less than five minutes.The performance of the humidification tower was better than expected. The humidified air out from the humidification tower is always saturated. The pinch point, i.e. temperature difference between the outcoming water from the humidification tower and the saturation temperature of the incoming air is around 3°C. The water circuit was closed, i.e. there was no need for additional water, when the flue gases after the flue gas condenser reached a temperature of 35°C.
The inhouse heat balance program, used for both cycle optimization and evaluation, has been verified. The evaporative gas turbine cycle has, when optimized, at least the same efficiency as the best combined cycle today, based on the same gas turbine. The evaporative cycle will also show very good performance when used in small scale power plants. Furthermore, it is possible to start the power plant very quickly from a remote place, and it is not in need of any cooling water. The investment cost for the evaporative cycle is much smaller than for the competing cycles.
Cooperative partners
- Royal Institute of Technology, Sweden
- Vattenfall Energy Utility, Sweden
- Sydkraft Energy Utility, Sweden
- Alstom Power, Sweden
- Swedish National Energy Administration
- ELFORSK, Sweden
- Elkraft, Denmark
Gas turbine manufacturer
Current research staff
Marcus Thern, Associate professor (Docent)
Phone: +46 46 222 41 12
Email: marcus.thern@energy.lth.se
Former staff
- Program manager: Prof. Tord Torisson, LTH, tord.torisson@energy.lth.se
- Torbjörn Lindquist, Ph.D.
- Per Rosén, Ph.D.
- Technician Björn Eriksson