Marine low-speed engine technology status and development trend

Marine engines are known as the heart of ships. More than 90 percent of ocean-going ships all over the world use low-speed engines in nowadays. In the field of marine low-speed engine, we can only produce the engines through patent license without the core research and development technologies. In terms of heavy parts for marine low-speed engines, we

Are mainly based on patented manufacturing, which requires a large number of imported electronic control systems, fuel systems, superchargers, bearing bushings, piston rings and other parts, leading to the “heart disease”in the shipbuilding industry. In order to solve this problem, shipbuilding industry in our country actively explored independent research and development of marine low-speed machinery and heavy parts over the years, and carried out a lot of fruitful work. Therefore, the China Shipping News specially opened up the Sound of Ship Machinery column, providing readers with a good academic and technical exchange platform. It is committed to promoting the establishment of marine low-speed machinery innovation and development technology system, the formation of China’s marine low-speed machinery research and development system and innovation capability.

--Editor

Data map/LASTAIR PHILIP WIPER

Marine low-speed engine industry status

Low-speed engines generally refer to reciprocating internal combustion engines with a speed of less than 300 RPM, which can be divided into 2 types according to different duels: low-speed diesel engines and low-speed dual-duel engines. The low-speed engine has the advantages of high power, high efficiency, long serve life, good reliability, easy operation and maintenance, and is the main propulsion power of ocean-going ships. According to statistics, 90 percent of the worlds maritime traffic is driven by low-speed machines.

In the 1950’s, there were more than a dozen of low-speed machine brands in the world. Due to the requirement of heavy investment, global service capabilities, and the benefits only being produced under a certain production scale, after a period of merging, acquisition and extinction, by the 1990s, there were only three low-speed machine brands: Man, Wartsila, and Mitsubishi Corporation, among which the Man was formed by the merging of the low-speed machinery businesses of the former German Man and Danish B&W, and Wartsula was acquired from Sulzer of Switzerland. In 2015, the former CSSC acquired Wartsila’s low-speed machinery business to form Winterthur Gas & Diesel(WinGD). In 2017, Mitsubishi Corporation’s low-speed engine business was merged with Kobe Engine Corporation to form Japan Engine Corporation(J-ENG). In nowadays, the three low-speed machinery brands in the world are MAN ES(Man renamed Man Energy Solutions), WinGD and J-ENG. J-ENG both have brands and products of their owns while the other two are only responsible for technical research and product design of low-speed machines, which are manufactured by authorized patent factories through licenses. Low-speed machine patent factories are mostly located in China, Japan and South Korea, which have almost manufactured all the low-speed machines in the world. South Korea has the highest output, and the daily outputs between China and Japan are equivalent. Among the enterprises in China, Hudong Heavy Machinery Co., LTD, a subsidiary of China Shipbuilding Group Co., Ltd occupies more than 20 percent of the market share of low-speed machinery manufacturing, ranking second in the world, lower than Hyundai.

Emission regulations promote the development of low-speed engine technology

The main driving factor for the technological development of low-speed engines in recent years is the International Maritime Organization (IMO) regulations on hazardous emissions. In order to meet the requirements of the Tier III regulations on nitrogen oxides that came into effect in 2016, selective catalytic reduction (SCR) and exhaust gas recirculation (EGR) technologies have been applied to low-speed diesel engines. SCR technology has a higher market share and is currently developing towards compact airborne technology. WinGD proposed an SCR on engine solution that integrates an SCR reactor and exhaust manifold, significantly reducing the space occupied in the cabin. Under the cooperation of low-speed engine research and manufacturing units in China and WinGD, the first low-speed engine using this technology will be manufactured in 2020 at Dalian Marine Diesel Engine Co., Ltd., a subsidiary of China Shipbuilding Group.

In 2016, the 70th meeting of the IMO Marine Environmental Protection Committee (MEPC70) set January 1, 2020 as the implementation date for the global standard of ship fuel sulfur content not exceeding 0.5% m/m. The installation of exhaust gas cleaning systems (EGCS) on ships has become one of the acceptable solutions for shipowners. According to the usage mode, EGCS can be divided into open, closed, and hybrid. The open system directly uses the alkalinity of seawater itself to clean the exhaust gas. The cleaned seawater is treated or directly discharged back into the sea, which has the characteristics of simple equipment, low initial investment and operating costs. However, some countries and ports restrict the discharge of wastewater from open systems within their control areas, including China.

After the implementation of sulfur emission restriction regulations in 2020, the use of low sulfur fuels has also become a possible option. The use of low sulfur fuel eliminates the obstacles to the application of wet combustion technology in the cylinder, that is, the problem of sulfur and water in the fuel corroding combustion chamber components no longer exists. Therefore, wet combustion technology has been developed in recent years.

MAN ES proposed two wet combustion technology solutions. One is the LGIM-W technology, which mixes methanol and water into the cylinder and ignites it with conventional diesel fuel. This technology has been applied to a 6G50ME model. Another type is PI FIW (Pilot Ignition Fuel In Water) technology, which ignites conventional diesel fuel and directly injects emulsified diesel fuel into the cylinder. Both of the above technologies can meet the requirements of Tier III.

JUMP (J-ENG Unique Marine Power) is a solution provided by J-ENG to meet emission reduction requirements such as sulfur, nitrogen oxides, and carbon dioxide. This scheme only uses marine light oil (MGO or MDO) and optimizes the combustion process through stratified cylinder water spraying technology. On the basis of meeting Tier II requirements, fuel consumption is reduced by 5% compared to conventional low-speed engines; After installing low-pressure EGR, it can meet Tier III requirements. In January 2019, J-ENG announced the successful operation of the first UEC50LSJ using JUMP technology.

Dual fuel technology can use new clean fuels such as methane, which is one of the solutions to emissions such as sulfur and particulate matter. MAN ES first launched the GI series of dual fuel low-speed engines with high-pressure gas injection, using diffusion combustion technology (Diesel cycle). In 2015, WinGD delivered the first low-speed dual fuel engine flexi-50DF using low-pressure gas injection. The DF series adopts premixed combustion technology (Otto cycle), with low nitrogen oxide emissions and no need for post-treatment devices to meet Tier III requirements, but diffusion combustion can only meet Tier II standards. In addition, the cost of low-pressure gas equipment is lower than that of high-pressure equipment. Due to technological and cost advantages, the WinGD DF series has quickly surpassed MAN ES's GI series, with a current market share of 70%. In 2019, Shanghai CSIC Mitsui Shipbuilding Diesel Engine Co., Ltd., a subsidiary of China Shipbuilding Corporation, delivered a 12X92DF with a rated power of 63840 kilowatts, becoming the world's largest dual fuel engine and the world's largest Otto cycle internal combustion engine in history.

Black carbon is the second largest source of global warming, second only to carbon dioxide, and is also one of the important causes of Arctic glacier melting. Ship power is the main source of Arctic black carbon. International ship black carbon reduction is still in the legislative stage, and black carbon reduction will be the next technological challenge faced by low-speed engines. The IMO Black Carbon Emission Measures Research Communication Group has identified 41 black carbon emission reduction measures, mainly including five research directions: fuel type, post-treatment technology, engine type, new power system, and ship operating parameters. Among them, light fuel technology, particle trap technology, and their combination are considered important means to solve the black carbon problem.

"Three Modernizations" Becoming the Development Direction of Low Speed Machine Technology

After years of development, it can be seen that intelligence, low carbonization, and integration are important directions for the future development of low-speed machine technology.

In recent years, intelligent ships have become a new hotspot in the international maritime community. International organizations such as the IMO and the International Organization for Standardization (ISO) have listed smart ships as important topics, and major international classification societies have successively issued normative or guiding documents related to smart ships. In 2016, China launched the "Intelligent Ship 1.0 R&D Special Project". At the end of 2018, the Ministry of Industry and Information Technology, the Ministry of Transport, and the State Administration of Science, Technology, and Industry for National Defense jointly released the "Action Plan for the Development of Intelligent Ships (2019-2021)", which emphasized "promoting the intelligent upgrading of marine equipment" as one of its key tasks. Low speed engines are the most important marine equipment for ocean going vessels, and their intelligent technology has become a key bottleneck restricting the leapfrog development of the shipbuilding industry.

In April 2018, the IMO MEPC 72nd meeting formulated a preliminary strategy for reducing greenhouse gas (GHG) emissions from maritime transportation, which determined the vision of achieving zero GHG emissions from shipping as soon as possible in this century. In June 2019, the 74th MEPC conference clarified the start time and reduction rate of the third phase of the Ship Energy Efficiency Design Index (EEDI). Overall, the start time was advanced and the reduction rate was increased. In response to greenhouse gas emission reduction requirements and energy efficiency regulations, countries around the world are conducting research on various technologies to improve low-speed engine energy efficiency and reduce carbon emissions. In terms of fuel, MAN ES is currently developing ammonia low-speed engines. Zero carbon and low-carbon fuels such as hydrogen, methanol, and biodiesel are also hot research topics both domestically and internationally.

In terms of system integration, hybrid power systems have typical applications on inland ships. On ocean going ships, low-speed engines are integrated with PTI/PTO to form a unified ship power grid with auxiliary systems, combined with energy storage units, forming the general form of ocean going ship hybrid power systems. The application of energy storage units can "peak shaving and valley filling" the load, making the host work under high-efficiency conditions as much as possible. When docking, stopping the main engine and using auxiliary engines or stored electrical energy to manipulate the ship can improve ship energy efficiency and reduce carbon emissions. Domestic and foreign enterprises and research institutions are conducting research on hybrid power systems for ocean going ships.

China's low-speed engine technology has made significant progress

China has always been committed to the independent development of low-speed engines, and there have been independent brand products in history. Under the current requirements of transformation, upgrading, and high-quality development in the shipbuilding industry, China should have its own low-speed engine brand and independent research and development, manufacturing, and service system. Acquiring a mature low-speed machine design enterprise to obtain a higher starting point is an effective and feasible way to achieve the leapfrog development of China's low-speed machine industry. Based on the above strategic considerations, in 2015, the former China Shipbuilding Group acquired Wartsila's low-speed engine business and established WinGD. At the same time, China Shipbuilding Power Research Institute Co., Ltd., a subsidiary of China Shipbuilding Corporation, has taken the lead in launching a major scientific research project for low-speed marine engines, actively carrying out research and development collaboration at home and abroad. Through more than four years of hard work, China's low-speed engine technology has made significant progress and achieved fruitful phased results.

As of now, the 400mm cylinder diameter low-speed engine dual fuel engine engineering prototype has fulfilled the shipment order; The low-speed diesel engine and dual fuel engine principle testing machine were successfully ignited and operated in Lingang, Shanghai. Both types of engines are the most advanced principle testing machines in the world, and their completion means that China has the world's most advanced low-speed engine whole machine testing platform; The development of core components for low-speed engines has also made gratifying progress. The electronic control system has been applied for engine matching, and the turbocharger and oil mist detector have obtained recognition certificates from China Classification Society, forming independent matching capabilities.

Driven by scientific research projects, various units in China adhere to the collaborative research and development model of "politics, industry, academia, research, and application", accumulate momentum, and strive to improve the innovation capacity of low-speed engines in China, build an independent and controllable low-speed engine industrial system, fill the gaps in the high-quality development of the shipbuilding industry, and continuously strive to enhance the international competitiveness of China's shipbuilding power and even the shipbuilding industry, striving to achieve the "Chinese Dream" of independent innovation and development of low-speed engines in China.