Wartsila deliver 1st LNG Powered Tugs for China

Wärtsilä, the marine industry’s leading solutions and services provider, is to deliver the main engines for 2 environmentally sustainable tugs being built for CNOOC Energy Technology & Services Limited (CETS), a subsidiary of the state-owned China National Offshore Oil Corp. (CNOOC).

The ships are the 1st prepared in advance series to be fueled by liquefied natural gas (LNG), and will be the 1st tugs in China ever to be use on gas. One of the first tugs in the world using dual-fuel. The commitment was made at the start of July 2012 and the order is included in the third quarter 2012 order book.

 The idea of CNOOC is to use more green energy in its work, and the Wärtsilä dual-fuel engine invention fits this profile the best way. The low emission levels is good for ships sailing close to crowded places inland, as tugs frequently are, while the high fuel efficiency enables lower operating costs. These 6500 bhp tugs will work along China’s coastline, and will be powered from the company’s own bunker points.

 First expected tugs from this type is expected to be delivered in one year.

Thi dual-fuel idea was 1st started in the early 1990s for use in land-based power plant applications. 

One of the reason of this type engines from Wärtsilä is its superior propulsion system. When using gas fuel, the nitrogen oxide (NOx) emissions are at least 85% under the current IMO regulations, and CO2 emissions are some 25% less than those of a conventional marine engine working on diesel fuel.

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Wärtsilä Hamworthy wins third FSRU

Hamworthy Oil & Gas Systems has secured a contract to supply its innovative LNG regasification technology for the third Höegh LNG Floating Storage and Regasification Unit (FSRU) under construction at Hyundai Heavy Industries.
Here’s how it works:

In this system, LNG is heated by propane in a closed loop and the propane is heated by seawater. In situations where the seawater is too cold to supply all the required heating energy, additional heat can be introduced.

The cascade concept is recommended instead of directly heat exchanging with seawater. LNG heat exchanged directly with seawater increases the risk of freezing the seawater in the heat exchanger. Propane as a secondary medium is suggested because of its thermodynamic properties with a low freezing point.

A HAZID analysis has been carried out with DNV to identify risks related to the design and operation of the regasification system. For example, it was concluded that the cascade system is a safer system than the pure seawater based.  LNG enters a cryogenic pump capable of producing the required send-out pressure (e.g. up to 130 bar has been studied). LNG at the required discharge pressure is heated in two stages.

In the first stage LNG is heated from -160°C to -10°C in a compact printed circuit heat exchanger with propane as a heating medium.

In the second stage, LNG can be heated further using seawater as a heating medium in a shell and tube heat
exchanger.

In the LNG/Propane heat exchanger, heat is exchanged against propane circulating in a closed loop. The propane enters the heat exchanger at approx. 0°C at 4.7 bar as gas. In the heat exchanging process propane is condensed, and leaves the exchanger in a liquid state at approximately -5°C.  The propane in the closed loop is then pumped by the circulating pump and heated against seawater in titanium semi welded plate heat exchangers. In these heat exchangers, the propane is evaporated and heated to 0°C before returning as gas to the printed circuit heat exchanger.

Working together with Sinopacific Offshore and Engineering (SOE), Wärtsilä Hamworthy will design and supply the system concept whilst the key equipment and fabrication will be supplied by SOE.

This partnership agreement follows on from the contract to supply a propane-seawater regasification system for the first two 170,000m3 capacity vessels signed in November last year.

Rendering courtesy Hoegh LNG

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Marine Solutions

Wärtsilä is passionate about optimising lifecycle value by offering whatever its customers in the marine industry need from the only complete portfolio of marine products, integrated solutions and services in the industry. The shorter route to bigger profits for the customers is offered by focusing on operational efficiency, environmental excellence, fuel flexibility and services.
Container vessel specifications

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