Marine Diesel Electric Propulsion

EARLY HISTORY
The first Diesel engine ever to be sold was an industrial unit of 44 kw, delivered in January of 1898 to the firm of A.G. Union, of Kempten, some 50 miles southwest of Augsburg, Germany. Meanwhile, a Swedish entrepreneur, Marcus Wallenburg, who had been impressed by a demonstration of the new engine, encouraged Rudolf Diesel to establish exclusive licensing arrangements for the manufacture of same. Eventually this led to a license being granted to the firm of Nya AB Atlas, at Sickla, Sweden, owned by Wallenburg and his partner Oscar Lamm. Subsequently this company became AB Diesels Motorer and more recently was renamed AB Atlas Copco. In February of 1898 a license also was acquired by a Russian company owned by the Nobel Brothers for manufacturing rights of Diesel engines in Russia, followed by a similar arrangement later that same year with the Danish firm of Burmeister &amp; Wain Shipyard, of Copenhagen but most of their early engines were prime movers for shore-based electric power plants. Evolution of Diesel propulsion plants for marine applications can be traced back to the world's first Diesel-powered ship, M.V. VANDAL, a 244 foot tanker designed under the direction of K. W. Hagelin who managed the petroleum transportation operations of Naphtaproduktions-Gesellschaft Gebruder Nobel.

The M.V. VANDAL was built by the Sormovs Shipyard at Nizhniy Novgorod In Russia in 1903.

Upon completion the hull was towed to the L. Nobel facility in Saint Petersburg to be fitted with three 3-cylinder single-acting Diesel engines of the four-stroke cycle, non-reversible type built by AB Diesels Motorer of Sickle, Sweden. These engines were designed with a bore of 0.299 meters, (11.77") Stroke of 0.430 meters (16.93") and rated at 120 bhp at 250 rpm. Each of the three main Diesel engines was directly connected to an 85 kw D.C. generator which in turn powered a reversible electric propulsion motor rated at 75 kw, directly connected to its respective propeller shaft, to provide a speed of 7 knots, fully loaded. This arrangement was attributable to the fact that directly-reversible Diesel engines had not yet been built and in fact did not appear until a few years later. Power for the electric steering gear, anchor windlass and a fire pump, plus navigation and accommodation lighting was furnished by an auxiliary generator. Two electrically driven cargo pumps were powered from one of the main propulsion generators and capable of discharging all 700 tons of cargo within 6 hours.

Although the M.V. VANDAL launched a new era in terms of marine propulsion, in keeping with the custom followed by the earliest of steam-powered ships she was fitted with two hinged masts each designed to support a staysail and a trysail. Her relatively shallow draft was originally required to ensure safe navigation through the rivers and canals and later in the Caspian Sea where she loaded crude oil at the port of Baku for delivery to St. Petersburg. Initially, the VANDAL was deployed to transport oil from Lake Ladozhskoye to Saint Petersburg but went aground in 1907, was re-floated, repaired and returned to service. In 1941 she was repositioned to the Caspian Sea but went on the rocks again during a storm in 1944, broke into two pieces and sank. After World War II she was salvaged, converted to a barge and given the name No. 1040.

The world's first directly-reversible marine Diesel engine, which was also the world's first two-stroke cycle Diesel engine, was exhibited at the Milan World Fair in 1906. This was a four cylinder in-line engine rated at 90.0 brake horse¬power, designed and built by the Swiss company of Sulzer Brothers, who in May of 1893 had secured a license from Dr. Rudolf Diesel for the exclusive use of his patents in Switzerland. It is worth noting that following undergraduate studies at the Munchen Polytechnikum in 1879, Rudolf Diesel became an apprentice engine fitter at the Sulzer Engine Works in Winterthur, Switzerland, where he learned how to build steam reciprocating engines and refrigeration compressors. Three years later he received his patent from the German Imperial Patent Bureau for his "compression-ignition engine concept", in 1882. He was also granted a British patent, No. 7241 by the British Patent Office Library in London later the same year, but his application to the U.S. Patent Office was not granted until July 16, 1885, three years after being submitted..

In 1911 Burmeister &amp; Wain built a large freighter, M.V.SELANDIA, for the Danish East Asiatic Company, powered by two B&amp;W Diesel directly-reversible four stroke cycle engines rated at 932 kilowatts each at 140 rpm. This 10,000 ton vessel was intended to be the world's first ocean-going motorship, but shortly before SELANDIA was launched, a Dutch built 59.6 meter tanker of 1,200 tons, the M.V. VULCANUS, powered by a 6 cylinder direct-drive, directly-reversible Werkspoor Diesel engine rated at 600 ihp at 165 rpm was completed and departed under her own power for Borneo where she operated for over twenty yrars.

DEVELOPMENT
One of the first U.S. Navy ships built with turbo-electric propulsion was the 12,000 ton Fleet Collier JUPITER, of 7,152 shp, launched 1912 and converted to an Aircraft Transport in 1921. By that time turbo-electric drive had been installed in at least six new battleships including the NEW MEXICO of 27,500 shp (1917), and the WEST VIRGINIA of 28,900 shp (1921). Despite the proliferation of electric propulsion in capital ships, the Navy refrained from adopting Diesel-Electric drive except for submarines for several years. Meanwhile in Europe, Diesel propulsion had become well established among merchant vessels such as the world's first large Diesel-powered passenger ship, the 17,490 ton AORANGI which entered service in 1924. Her quadruple-screw propulsion plant consisted of four Sulzer 6ST70, 6-cylinder 2-stroke cycle Diesel engines with a total output of 13,000 bhp at 127 rpm. Larger marine Diesels soon became quite common, such as the Sulzer S90 type, 5-cylinder engines with a bore of 90 cm, and mcr rating of 4,650 bhp at 80 rpm, built in 1929 by John Brown under license from Sulzer Brothers. However, for the next 12 years steam turbines appeared to be the propulsion plant of choice for most naval and merchant vessels built in the United States until World War II when the U.S. Navy built a series of Destroyer escorts, some with 6,000 shp Diesel-Electric propulsion and others with 12,000 shp turbo-electric propulsion. In addition, seven 19,200 ton Submarine Tenders of the FULTON Class were built with 11,200 bhp Diesel-Electric drive. At the same time the U.S. Maritime Commission approved the construction of several hundred support ships including numerous oil tankers powered by turbo-electric propulsion plants.

A Diesel-Electric Super Liner
In 1929 the White Star Line, ordered construction of a super passenger liner, from the Harland &amp; Wolf Shipyard in Belfast, Ireland. This ship was designed to be 1,000 feet in length, featuring a multiple engined Diesel-Electric propulsion plant with a combined rating of 200,000 shaft horse power driving four propellers. The main propulsion plant was to consist of forty seven 6-cylinder, 4-stroke cycle, single-acting turbocharged Diesel engines operating at 260 rpm and coupled to Direct Current generators, to power the 24 foot diameter D.C. propulsion motors. Due to the economic depression of that era and resultant drop in world trade, construction of this super line was halted and never resumed.

After the depression, the White Star Line merged with Cunard Line and became known as the Cunard White Star line, resulting in the revival of the super liner concept, but with some changes. The outcome was the construction of the RMS QUEEN MARY in the mid-thirties, and subsequently the RMS QUEEN ELIZABETH, both of which were steam turbine powered. With the outbreak of World War II both ships were pressed into service as troop carriers and safely transported thousands of American service men across the Atlantic and elsewhere. Since the end of World War II Diesel-Electric propulsion has been applied to Ferry Boats, Tugboats, Ice Breakers, Oil Tankers, Oceanographic Research vessels and large size passenger cruise ships. An outstanding example of the latter is the current flagship of the Cunard Line, RMS QUEEN ELIZABETH II, (known as the QE2) which was converted from steam turbine to Diesel-Electric drive, rated at 44 megawatts on each of two screws. The QE2 was one of the first cruise liners to adopt alternating current (AC) propulsion rather than direct current (DC) that has been in use for over seventy years. This conversion from steam to Diesel, completed in 1987, may be seen by traditional marine Diesel advocates as the ultimate vindication of the original White Star Line Diesel-Electric super liner concept of the late twenties. The re-engining of the QUEEN ELIZABETH II was performed by the Lloyd Werft Shipyard in Bremerhaven, Germany, in 180 days, from October 1986 to April 1987, at an estimated cost of $53,000,000.00, resulting in the world's most powerful Diesel-Electric propulsion plant of any merchant vessel afloat. The nine 9L 58/64 MAN-B&amp;W Diesel engines rated at 14,445 bhp each, provide power to twin GEC 44 MW, 60 cycle synchronous propulsion motors turning at 144 rpm to produce a speed of 33 knots. In addition to the low specific fuel consumption for which these engines are noted, the overall conversion design includes an extensive waste heat recovery system with a total thermal efficiency of 74 per cent. Waste heat is recovered from engine exhaust by a series of exhaust gas boilers plus other means of heat recovery from engine jacket cooling water and turbo-charger inter-cooler to evaporate 1,000 tons of fresh water per day from sea water, resulting in a reduction of fuel consumption of approximately 250 tons per day.

Since the early 1990's several other cruise line owners have opted for Diesel-Electric propulsion and currently there are eighteen large passenger cruise ships either in operation or under construction for which Diesel-Electric propulsion has been selected. One of the many reasons for this preference is that operating experience has shown a remarkable reduction in noise levels and amplitude of vibration, particularly on ships equipped with outboard propulsion pods of the azimuthing type. This factor contributes significantly to the overall comfort of passengers. The Carnival cruise ship M.S. ELATION and her sister ship M.S. PARADISE were the first Wartsila Diesel-Electric powered vessels.

ADVANTAGES OF DIESEL-ELECTRIC DRIVE
It is evident that Diesel-Electric drive offers many advantages over steam turbine plants, medium speed geared Diesel drive, or slow speed Diesel direct drive. Initial cost is somewhat higher but actual operating expenses are lower due to reduced engine room manning, reduced maintenance work load and greater fuel economy. Other favorable factors include the feasibility of tailoring power production (hence fuel consumption), to actual load requirements within the desired speed range. Since propeller speed can be varied by changing the propulsion motor rpm, the prime movers (Diesel engines) are allowed to run at normal designed operating speed. This in turn allows for greater fuel economy, maximum efficiency and reduced air pollution by nitrogen oxides in the exhaust emissions, as a result of optimized combustion and more stable engine loading. Furthermore, changing from the ahead to the astern direction is accomplished simply by reversing the rotation of the propulsion motor(s). For special purpose vessels including naval minesweepers; missile tracking vessels; anti-submarine patrol vessels; and commercial vessels such as fishing trawlers, ice breakers: seismic survey vessels; oceanographic and fisheries research vessels, the ability to cruise at slow speed for prolonged periods of time is a pre-requisite. This capability is yet another area in which the precise controllability of Diesel-Electric drive has proven itself to be a worthy alternative to competitive conventional drive systems. This advantage is attributable to the flexibility of the Diesel-Electric power plant system that enables propulsion motors to be operated at very low speeds continuously for several days, without imposing a corresponding penalty on the prime mover(s). With direct-drive Diesel or geared-drive Diesel this type of duty would normally result in loss of efficiency due to improper fuel-air ratio, incomplete combustion, smoky exhaust, carbon build-up and higher specific fuel consumption. The favorable fuel economy of Diesel-Electric drives, coupled with the corresponding reduction in labor intensive operation and maintenance, tend to off-set to the somewhat higher initial acquisition cost compared to competitive propulsion systems. Ultimately the inherent savings reach a point whereby the initial investment differential is amortized by the "chain-reaction effect" that manifests itself in improved fuel economy, smaller engine room crew, fewer maintenance workers, and reduced expenditure for repair parts and materials, with less down time. The reduction in manning implies not only lower direct labor costs and fringe benefits, but with less need for maintenance there will be a proportional savings in overtime. Besides fewer crew members required there will be a reduction in the food budget, less potable water consumption and less laundry. There will also be further savings in travel expenses resulting from flying fewer relief crew members for crew-changes at overseas ports.

DIESEL-ELECTRIC PROPULSION TECHNOLOGY
Direct Current (DC) has been used for marine Diesel-Electric propulsion plants since 1903 almost exclusively until the trend toward Alternating Current (AC) first appeared around 1960. For the next twenty years there was a gradual but persistent shift towards the adoption of AC for power generation, propulsion control and drive purposes. This was mainly attributable to the trend toward higher propulsion power in excess of 10 MW per shaft, for which the corresponding weight and space requirements of DC machinery became unacceptable. However, since the early eighties, subsequent developments in electrical technology have made AC systems far more efficient, much lighter and more compact, besides requiring less maintenance than their DC counterparts, thereby contributing to greater economy of operation. For main propulsion power requirements in excess of 20 MW per shaft, two or more propulsion motors can be installed either in tandem on a common shaft, or geared to the shaft in parallel, reflecting the inherent flexibility of Diesel-Electric propulsion. The above mentioned advantages of AC systems however, are not limited to Diesel-Electric main propulsion plants but are equally applicable to other machinery systems served by the concept of a sea-going "Power Plant", such as dynamic positioning thrusters, and petroleum cargo pumps for shuttle tankers; bow and stern thrusters, air-conditioning plants,refrigeration systems and passenger elevators aboard large cruise liners. Taking this technology a step further, ABB has also introduced the Sami Megastar Pulse Width Modulator (PWM) frequency converter for control of AC cage induction motors. PWM units are currently available with power ratings in the 8 MW range, which equates to approximately 10,700 bhp per drive, and for speed ranges from 0 to 900 rpm or 0 to 1,800 rpm. This type of drive is suitable for control of either main propulsion motors or thrusters of dynamically positioned vessels in addition to auxiliary machinery such as compressors, pumps and winches. Due to the rather high power factor of almost unity, the relative efficiency of PWM systems is approximately 2% more than a conventional DC drive of comparable power. A significant advance in electrical engineering technology has been achieved by Asea-Brown-Boveri (ABB) since 1983, in the successful development of the Cyclo-converter, (Cyclo), many of which have been installed aboard several large European-built passenger cruise ships, icebreakers, oil tankers and ferries. The Cyclo propulsion control system has earned recognition within the marine industry as one of the most advanced forms of AC engineering technology for shaft power requirements higher than 7 MW (approximately 9,400 shp). This is evidenced by the numerous installations of ABB Marine Cyclo-converters on passenger cruise ships; icebreakers; oil tankers and cable laying ships since 1983. Likewise, the PWM drive system is now the system of choice for controlling multiple induction motors among smaller vessels. Both systems are well suited to the "Power Plant" concept which is rapidly gaining favor among ship-owners around the world.

Links
Fuel Cells for Marine Propulsion

Alternate Fuels for Marine Propulsion Plants

The Evolution of Steam Engines

Diesel Engine Exhaust Gas Emissions And The Effects Of Alternate Fuels