ORC and EGR Scrubber integration

01/25/2017 - 15:00-01/25/2017 - 16:30


Fredrik Ahlgren
(Linnaeus University)
Marcus Thern
(Lund University)
Magnus Genrup
(Lund University)
Maria E. Mondejar
(Technical University of Denmark)


Energy Efficient Ship Design and Operation (Part C)

Dimitrios Dalaklis
Fredrik Ahlgren

The vast majority of ships trafficking the oceans are fuelled by residual oil with high content of sulphur, which produces sulphur oxides (SOx) when combusted. Moreover, the high pressures and temperatures in modern diesel engines also produce nitrogen oxides (NOx). These emissions are both a hazard to health and the local environment, and regulations enforced by the International Maritime Organization (IMO) are driving the maritime sector towards the use of either distillate fuels containing less sulphur, or the use of exhaust gas cleaning devices. Two common techniques for removing SOx and limiting NOx are the open loop wet scrubber and exhaust gas recirculation (EGR). The scrubber sprays sea water in the exhaust forming sulphuric acid which is then discharged to the sea, and nitrogen oxides are limited by recirculating parts of the exhaust gas. A scrubber and EGR installation reduces the overall efficiency of the system as it needs significant pumping power, which means that the exhaust gases are cleaner but at the expense of higher CO2 emissions.

In this paper we propose a method to integrate an exhaust gas cleaning device for both NOx and SOx with an organic Rankine cycle for waste heat recovery, thereby enhancing the system efficiency. We propose two optimised ORC configurations, integrated with the energy flows from both an existing state-of-the-art EGR system and an additional open loop wet scrubber.