Unconventional Prime Movers for Large Ships / Combined cycles and waste heat

Owing to current and future regulations regarding fuel quality and pollutant emissions, there is an increasing interest in novel technologies that may reduce the environmental consequences of shipping. In this project alternatives to the two-stroke diesel engine as prime mover for large ships are studied from a systems perspective.

The research is aimed at finding technologies that may offer advantages in terms of environmental impact, performance, and possibly also operational costs. The technologies under consideration are gas turbine-based solutions like gas turbine/steam turbine combined cycle power plants, and gas turbine/fuel cell combined cycles.

Illustration of a combined cycle power plant featuring two gas turbines and a single-pressure steam cycle.

With advanced thermodynamic modelling the efficiency and performance of combined cycles with gas and steam turbines and the performance of waste heat recovery systems is successfully modelled by Fredrik Haglind and his researchers at DTU Mechanical Engineering.

Based on his own research and supportive master projects from a number of students, Ph.D. Fredrik Haglind and his team have made an impressive study of combined cycles for marine applications. Their findings and research have been documented in a number of papers and implemented in the thermodynamic Dynamic Network Analysis (DNA) model at DTU Mechanical Engineering.

The result is that DTU Mechanical Engineering today has an advanced thermodynamic modelling system for calculation and optimisation of gas and steam turbines in combined cycles and in complex waste heat systems. The DNA model has been applied in a number of practical assignments for demonstration. As an example the model has been used for simulation and optimisation of a waste heat recovery system on a Post-Panamax Container vessel from Maersk Line.

The main focus of this particular project was the performance and optimisation of waste heat recovery systems including also part load conditions, which in many cases are not advantageous.

The results from the project suggest that an alternative turbocharger configuration where two compressors with intercooling are combined with a two-pressure level steam cycle will be advantageous as this configuration offers large improvements in performance.

Furthermore, the model has been used on a large container vessel to demonstrate and evaluate the performance of a traditional diesel engine versus an alternative propulsion system using gas and steam turbines in a combined cycle machinery system.

The results of this design study clearly show that the combined cycle system has advantages in terms of space and weight, whereas the diesel engine is favourable when considering part load conditions. Also the two-stroke diesel engine is still favourable in terms of large flexibility in fuel oil grades, ranging from high distillate diesel oil qualities to low fuel oil qualities.

The DNA model has recently been used with Molslinien A/S in a project within the Green Ship of the Future project. In this project, Fredrik Haglind and Otello Barduca made a design study of a LNG powered fast ferry with gas turbines and waste heat recovery system. The project showed that it is possible to use LNG powered gas turbines in a fast ferry, resulting in significantly reduced emissions of nitrogen dioxide and sulphur.

Papers by Fredrik Haglind:

Published:

1. Haglind F. 2009, “Variable geometry gas turbines for improving the part-load performance of marine combined cycles - Gas turbine performance,” Energy, Vol. 35, pp. 562-570.
2. Haglind F. and Elmegaard B., 2009, “Methodologies for predicting the part-load performance of aero-derivative gas turbines,” Energy, Vol. 35, pp. 1484-1492.
3. Haglind F., 2008, “A review on the use of gas and steam turbine combined cycles as prime movers for large ships, Part I: background and design,” Energy Conversion and Management, Vol. 49, Issue 12, pp. 3458-3467.
4. Haglind F., 2008, “A review on the use of gas and steam turbine combined cycles as prime movers for large ships, Part II: previous work and implications,” Energy Conversion and Management, Vol. 49, Issue 12, pp. 3468-3475.
5. Haglind F., 2008, “A review on the use of gas and steam turbine combined cycles as prime movers for large ships, Part III: fuels and emissions,” Energy Conversion and Management, Vol. 49, Issue 12, pp. 3476-3482.

Under review:

• Haglind F. 2010, “Variable geometry gas turbines for improving the part-load performance of marine combined cycles -  Combined cycle performance,” submitted.

Reports:

• Barduca O. and Haglind F., 2009, “Optimization of the waste recovery system for a marine slow-speed diesel engine, Part I: full-load performance.”
• Barduca O. and Haglind F., 2009, “Optimization of the waste recovery system for a marine slow-speed diesel engine, Part II: part-load performance.”

 Please contact Fredrik Haglind (frh@mek.dtu.dk) in order to receive a copy of the papers above.