MARINE POWER PLANT POLLUTANT EMISSIONS
Abstract：This paper presents a comparison of toxic chemical emissions comprised in exhaust flows/fluxes of marine thermal engines of different types: diesel, gas and steam turbines (including boilers). Their impact on the environment was studied taking into account the engine type and its function in the ship power system.
Keywords: marine power plant, emission, exhaust gas, diesel engines, gas turbines,
steam turbines, boilers
1. Introduction
A ship differs in many aspects from other means of transport, such as trucks or railway [2]. In addition to transporting different types of goods or passengers, a ship must also contain accommodation and other necessary facilities for the crew. In many cases it must also be able to handle different kinds of cargo in the harbours. In order to make this possible, a ship must be capable of a high degree of self sufficiency and of handling its own energy supply under very varying conditions. This is why ships are equipped with different types of energy suppliers.
These are identified as the main engine, auxiliary engines and the boiler.The principal sources of marine exhaust emissions are as follows:
- main engine – used for propulsion,
- auxiliary engine – used for the generation of electricity,
- boiler.
The propulsion engines installed in today#39;s ships are of the following types:
- diesel engines
- gas turbines,
- steam turbines.
Steam for turbines is produced by burning fossil fuels. Steam powered vessels are rapidly disappearing from merchant fleets because their specific fuel consumption is approximately 300g/kWh, which is nearly twice as much as that of a modern diesel engine.
2. Chosen Pollutant in Exhaust Gases
There is increasing interest at all levels of society into harmful emissions to the atmosphere.This section compares the emissions from the various propulsion system options .The diesel engine has undergone a powerful development process resulting in a completely new generation of engines with considerably improved performance. The specific fuel consumption of a modern two-stroke diesel engine may be in the order of 160 g/kWh, as comparedto 210 g/kWh for older engines.
Today the largest two-stroke diesel engines have an output of over80 MW, which should be sufficient even for future proposed high-speed container ships. Owing to the high efficiency of diesel engines, the emissions of CO2, CO and hydrocarbons are relatively low, however, high emissions of NOX are also characteristic of diesel engines. The same high combustion temperatures that give a high thermal efficiency in the diesel engine are also most conducive to NOX formation. By running on low quality fuels with a low fuel consumption, large diesel engines offer enormous savings in fuel costs compared with those of alternative prime movers.
On some smaller, more specialized ships such as cruise ships, diesel-electric engines have been installed. This means that the electrical output from several diesel-electric generators, running at constant speed, have been connected to each other. The propulsion then occurs by means of large electric motors, contrary to the conventional way wherein the propeller is fitted on a shaft connected directly, or via a driving gear, to the main engine. However, diesel-electric propulsion is still uncommon today except in cruise ships and in some of the smaller passenger-car ferries. As regards emissions, diesel-electric propulsion does not lead to any significant difference compared to a conventional installation and may experience a net increase in emissions due to the lower efficiency of the total system.
Gas turbines are characterized by the combination high output/low weight. As such they are widely used in military ships and in modern fast ferries. But their fuel efficiency is low (total approx. 215 g/kWh) as compared with diesel engines (approx 160 – 180 g/kWh), which makes them uneconomic for most commercial vessel applications. However, gas turbines are recently appearing in cruise ships where they are used to augment diesel-engined gensets. Princess Cruisersquo;s new Coral Princess, for instance, uses a 30,2 MW gas turbine (General Electric LM2500 ) in conjunction with two Wartsila diesel engines (Model 9L46 @ 9.45 MW and Model 8L46 @ 8.4MW). The gas turbine is used as a low-emission power source while hoteling as well as to meet peak power demands. The two diesels meet normal cruising power requirements. They have a fuel efficiency (85% load) of 180 g/kWh, as compared with 215 g/kWh for the LM2500 gas turbine.
Steam for steam turbines may be produced by burning fossil fuels or by means of nuclear reactors. Steam powered vessels are rapidly disappearing from merchant fleets because their specific fuel consumption is approximately 300 g/kWh, which is nearly twice as much as that of a modem diesel engine. Some steam powered ore carriers apparently still ply the Great Lakes, and a single steam powered cruise ship visits the Port of Vancouver during the summer months.
However, these vessels are a small minority of the total marine vessel fleet and hence steam engines will not be addressed in the following sections.
Auxiliary engines are running almost constantly in order to take care of part of the ship#39;s power supply. Power is needed for pumps, cranes, cooling and heating plants, lighting, etc. Some ships have generators connected to the shaft of the main engine (known as shaft generators). These substitute for the auxiliary engines, usually while cruising at sea when the main en
全文共26945字，剩余内容已隐藏，支付完成后下载完整资料
MARINE POWER PLANT POLLUTANT EMISSIONS
Abstract：This paper presents a comparison of toxic chemical emissions comprised in exhaust flows/fluxes of marine thermal engines of different types: diesel, gas and steam turbines (including boilers). Their impact on the environment was studied taking into account the engine type and its function in the ship power system.
Keywords: marine power plant, emission, exhaust gas, diesel engines, gas turbines,
steam turbines, boilers
1. Introduction
A ship differs in many aspects from other means of transport, such as trucks or railway [2]. In addition to transporting different types of goods or passengers, a ship must also contain accommodation and other necessary facilities for the crew. In many cases it must also be able to handle different kinds of cargo in the harbours. In order to make this possible, a ship must be capable of a high degree of self sufficiency and of handling its own energy supply under very varying conditions. This is why ships are equipped with different types of energy suppliers.
These are identified as the main engine, auxiliary engines and the boiler.The principal sources of marine exhaust emissions are as follows:
- main engine – used for propulsion,
- auxiliary engine – used for the generation of electricity,
- boiler.
The propulsion engines installed in today#39;s ships are of the following types:
- diesel engines
- gas turbines,
- steam turbines.
Steam for turbines is produced by burning fossil fuels. Steam powered vessels are rapidly disappearing from merchant fleets because their specific fuel consumption is approximately 300g/kWh, which is nearly twice as much as that of a modern diesel engine.
2. Chosen Pollutant in Exhaust Gases
There is increasing interest at all levels of society into harmful emissions to the atmosphere.This section compares the emissions from the various propulsion system options .The diesel engine has undergone a powerful development process resulting in a completely new generation of engines with considerably improved performance. The specific fuel consumption of a modern two-stroke diesel engine may be in the order of 160 g/kWh, as comparedto 210 g/kWh for older engines.
Today the largest two-stroke diesel engines have an output of over80 MW, which should be sufficient even for future proposed high-speed container ships. Owing to the high efficiency of diesel engines, the emissions of CO2, CO and hydrocarbons are relatively low, however, high emissions of NOX are also characteristic of diesel engines. The same high combustion temperatures that give a high thermal efficiency in the diesel engine are also most conducive to NOX formation. By running on low quality fuels with a low fuel consumption, large diesel engines offer enormous savings in fuel costs compared with those of alternative prime movers.
On some smaller, more specialized ships such as cruise ships, diesel-electric engines have been installed. This means that the electrical output from several diesel-electric generators, running at constant speed, have been connected to each other. The propulsion then occurs by means of large electric motors, contrary to the conventional way wherein the propeller is fitted on a shaft connected directly, or via a driving gear, to the main engine. However, diesel-electric propulsion is still uncommon today except in cruise ships and in some of the smaller passenger-car ferries. As regards emissions, diesel-electric propulsion does not lead to any significant difference compared to a conventional installation and may experience a net increase in emissions due to the lower efficiency of the total system.
Gas turbines are characterized by the combination high output/low weight. As such they are widely used in military ships and in modern fast ferries. But their fuel efficiency is low (total approx. 215 g/kWh) as compared with diesel engines (approx 160 – 180 g/kWh), which makes them uneconomic for most commercial vessel applications. However, gas turbines are recently appearing in cruise ships where they are used to augment diesel-engined gensets. Princess Cruisersquo;s new Coral Princess, for instance, uses a 30,2 MW gas turbine (General Electric LM2500 ) in conjunction with two Wartsila diesel engines (Model 9L46 @ 9.45 MW and Model 8L46 @ 8.4MW). The gas turbine is used as a low-emission power source while hoteling as well as to meet peak power demands. The two diesels meet normal cruising power requirements. They have a fuel efficiency (85% load) of 180 g/kWh, as compared with 215 g/kWh for the LM2500 gas turbine.
Steam for steam turbines may be produced by burning fossil fuels or by means of nuclear reactors. Steam powered vessels are rapidly disappearing from merchant fleets because their specific fuel consumption is approximately 300 g/kWh, which is nearly twice as much as that of a modem diesel engine. Some steam powered ore carriers apparently still ply the Great Lakes, and a single steam powered cruise ship visits the Port of Vancouver during the summer months.
However, these vessels are a small minority of the total marine vessel fleet and hence steam engines will not be addressed in the following sections.
Auxiliary engines are running almost constantly in order to take care of part of the ship#39;s power supply. Power is needed for pumps, cranes, cooling and heating plants, lighting, etc. Some ships have generators connected to the shaft of the main engine (known as shaft generators). These substitute for the auxiliary engines, usually while cruising at sea when the main en
全文共35201字，剩余内容已隐藏，支付完成后下载完整资料
资料编号：[16866]，资料为PDF文档或Word文档，PDF文档可免费转换为Word
以上是毕业论文外文翻译，课题毕业论文、任务书、文献综述、开题报告、程序设计、图纸设计等资料可联系客服协助查找。
