新版轮机英语unit4 Fuel oil system

Lesson 4 Fuel oil system理解燃油的净化

供给和燃油系统的操作

补充内容燃油的参数：combustion Fuel oil’s viscosity(粘度), cetane number(16烷值), calorific value(燃烧值), the sulphur content(硫分), its carbon residues(残炭值)

Ash (灰分)

maintenanceflash point(闪点), setting point(倾点),

specific gravity(比重), viscosity(粘度 cst), water content(水分), mechanical impurities(机械杂质)

Fuel oil supply system(燃油输送系统):Fuel supply deals with the provision(预备)

of the fuel oil suitable for the use by the injection system.

Fuel injection system(燃油喷射系统)The function of fuel injection system is to

provide the amount of fuel at the right moment and in a suitable condition for the combustion process.

The “unifuel” systemThe common system covers the entire fuel flow from storage tank(储存舱) to injection into the engine cylinders. Uni- 单一，一个

【1】With regard to(关于) centrifuge recommendations, fuel oils should always be considered as contaminated (污染)upon delivery (交付)and should therefore be thoroughly cleaned to remove solid as well as liquid contaminants before use.

The solid contaminants in the fuel are mainly rust, sand, dust, and refinery(精炼) catalysts(催化剂). Liquid(液体) contaminants are mainly water, i.e. either fresh water or salt water.

Impurities in the fuel can cause damage to fuel pumps, and fuel valves, and can result in increased cylinder liner wear and deteriorations(磨损损耗，变坏) of the exhaust valve seats.

Also increased fouling(弄脏) of gas ways and turbocharger blades may result from the use of inadequately(不足的，不适当的) cleaned fuel oil.

Effectively cleaning can only be ensured by using a centrifuge(离心分离机).

【2】Results from experimental work on the

centrifuge treatment of today’s residual fuel qualities have shown that the best cleaning effect, particularly in regard to removal of catalytic fines, is achieved when the centrifuges are operates in series, i.e. in purifier/clarifier mode.

This recommendation(推荐，建议) is valid(有效的，正确的) for conventional centrifuges.

For modern types, suitable for treating fuels with densities higher than 991kg/m3 at 15℃, it is recommended to follow the maker’s specific instructions(说明).

【3】In view of(由于，考虑到) the fact that some fuel oil standards incorporate fuel grades without a density limit, and also the fact that the traditional limit of 991kg/m3 at 15℃ is occasionally exceeded on actual deliveries,

Some improvements in the centrifuging treatment have been introduced to enable the treatment of fuels with higher density.