strength, and to provide some sort of cooling, usually bore cooling.一种替代方法是围绕汽缸套的上部设计水套，也就是钻孔冷却。，缸套的上部较厚，提供足够的强度，也可以实现一些冷却。
CYLINDER HEAD 汽缸盖
The cylinder head must effectively close the upper part of the cylinder and provide space for air inlet and exhaust valves, a fuel injector and a number of other fittings such as air start valve, relief valve and indicator cock. 汽缸盖必须有效地封住汽缸的上部，为进排气阀、燃油喷射器，还其他一些装置如：空气启动阀、安全阀和示功考克等提供安装空间，In Vee type engines it is usual to fit air start valves to one bank of cylinders only. 在V型机上，通常只在一列汽缸上安装启动空气阀。The head must resist mechanical stress due to peak firing pressure and must also be cooled to maintain strength. 汽缸盖必须能够承受爆发压力所产生的机械应力，必须冷却以保持强度。As with cylinder liners, cooling can present problems related to thermal stress and an effective system of coolant circulation is needed. 汽缸套的冷却可能存在热应力问题Although many cylinder heads still employ cored-out cooling spaces, some engines (e.g. Sulzer 'Z' range) make use of bore cooling systems. 尽管很多汽缸盖采用中空冷却腔冷却I，但是一些柴油机（如：苏尔寿Z系列）采用钻孔冷却方式。n some cases combined bore and cavity cooling is used, with the bores located at the lower face closest to the combustion chamber where the cooling effect is critical. 一些时候，钻孔冷却和冷却腔冷却会混合应用，钻孔在汽缸盖的下表面紧靠燃烧室，这里的冷却效果很关键。This lower face is known as the 'flame plate'.下表面一般称作“底板” The cylinder head sits on the top of the liner and holds it in place. 汽缸盖位于汽缸套上面，并固定汽缸套A number of hydraulically tightened studs are usually employed to hold the head onto the cylinder block.一些液压上紧螺栓通常用来把汽缸盖固定到汽缸体上 Cooling water flows from the cylinder liner to the cylinder head either directly, with self sealing connections, or by means of connecting pipes. 汽缸套和汽缸盖之间密封连接或采用连接管后，冷却水直接从汽缸套流向汽缸盖Water outlet flow is fro m the top of the head to a common flow pipe. 冷却水从汽缸盖上部流出到到一个公共管路。Some form of air vent arrangement is usually provided at the water outlet pipe to ensure removal of air from the coolant passageways following overhaul.在冷却水出口管通常安装一些除气装置，用以大修后从冷却管路中驱除气体。 For most engines each unit, cylinder liner jacket and head, can be isolated from the coolant circulating system so it is only necessary to drain the unit being overhauled. 对于大多数柴油机，汽缸套、水套和汽缸盖各单元都可以从冷却循环中独立出来，所以各单元大修时仅需要单独放空。The cylinder head also connects to the air inlet and exhaust trunkings, passageways are cast into the cylinder head to permit the flow of combustion air and exhaust gas.汽缸盖也连接到空气入口和排气管，这些通道铸造在汽缸盖上，允许新鲜空气流入废气排出。
LESSON 5
Lubricating Oil Of Today 现今的润滑油
The fuel of today contains more sulphur and slow burning components such as asphaltenes than before. 现今的燃油比以前含有更多的硫和不易燃烧的成分如沥青。The aromaticity of
fuels has increased. 燃油里的芳香族化合物也增加。Engine design has changed, aimed towards reduced operating costs. 为了降低运行成本，柴油机的设计也改变了。The output per cylinder, the engine pressures and temperatures, have increased in order to make it possible to burn less, but heavier fuel. 每个汽缸输出的压力和温度都增加了，这样可以燃烧更少、更差的油。The lube oil consumption is reduced. 润滑油的消耗量增加了。To hold back on the investment cost there is a trend towards smaller sump volumes.为了降低投资成本，也有一个向小型油底壳的发展趋势。
These changes increase the stress on and the amount of contaminants in the lube oil.这些改变增加了应力和润滑油中污染物的数量。 Further, as effects of the increased use of heavy fuel the classification societies indicate bearing problems with focus on the lubricating oils. 进一步来说，船级社指出随着低质燃料油使用增加的影响，轴承的一些问题主要集中在润滑油上。The lube oils today have been developed to meet the increased demands. 现今的润滑油为了适应不断增加的要求，也有了很大的发展。Higher sulphur content in the fuel oil has been counteracted by a higher TBN. 含硫值较高燃油的用总碱值较高的润滑油中和其酸性产物。In order to keep the engine clean and avoid agglomeration of sludge particles, more detergent and dispersant additives are used. 为了保持气缸内的清洁，避免泥渣颗粒结块会使用更多的清洁剂和分散剂。The trend towards reduce manning in the engine room less man-hours for adjusting, cleaning and repair of the equipment.为了降低机舱里的人员配员，调整、清洁和修理设备的工时也要少。 The increased contaminants in the lube oils must be efficiently removed by cleaning equipment with a constantly high separation performance. 润滑油里增加的污染物必须要通过一个稳定的高分离性的设备有效的清除。The detergent and dispersant properties of the lube oil make separation a difficult task. 润滑油中清洁剂和分散剂的存在使得润滑油分离困难。These additives keep the particles small or even break them up. 这些添加剂的存在使得颗粒更小甚至使颗粒破碎。Removal of water is also made difficult due to the increased dispersant properties. 由于分散性能的增加，清除水也变得困难。In extreme cases it is even possible that the lube oil picks up water from the water seal of a purifier if the oil and water are brought into turbulent content with each other. 在一些极端的情况下，润滑油可能从分油机的水封水中吸收水，如果水和润滑油剧烈的混合在一起。Another complicating factor is that some of the additives e.g. over-base detergents, are more or less sensitive to contact with water and will deplete and form deposits themselves. 另外一些复杂的因素是一些添加剂，如高碱性清洁剂几乎都对水接触比较敏感，自身浓度降低并形成沉淀。Combustion by-products in the lube oil also increase due to the changed properties of the fuel oil. 燃油性质的变化也会导致润滑油中燃烧副产品增加。Separated sludge is stickier, which makes it difficult to discharge from self-cleaning centrifugal separators.分离出来的泥渣是粘稠的，要从自清洗分离机上清除掉这种泥渣很困难。
Conventional cleaning plants are based on purifier type separators. 传统的清洁装置是基于净化器式分油机。During operation, cleaned oil and separated water continuously discharged. 在运转过程中，清洁的油和分离出来的水连续排出来。An interface is formed in the bowl between the water and the oil.在水和油之间在分离同内部形成一个油水分界面。 This interface position is affected by several factors, such as density, viscosity, temperature and flow rate.这个分界面的位置取决于几个因素，如密度、粘度、温度和流量。
To achieve the best possible separator, the interface must be located between the outer edge of the top disc and the disc stack. 为了获得最好的分离效果，分界面必须位于盖盘的外边缘和分离盘组之间。If the interface enters the disc stack, the oil to be cleaned will pass only through the lower part of the disk stack, since the upper part is blocked with water.如果分界面进入分离
盘，要清洁的油就只从分离盘下部经过，上半空间充满了水。 Thus, separation is inefficient because only part of the disc stack is being used. Should the interface move outside the top disc the oil will escape through the water outlet. 因此分离效果不好，这是因为只有部分分离盘片有效利用。To obtain a correct interface the purifier must be fitted with a correct gravity disc. 为了获得正确的分界面，分油机必须安装正确的重力环。A too large gravity disc may cause a broken water seal and oil losses. 一个太大的比重环会破坏水封造成跑油。A too small gravity disc contributes to poor separation efficiency and carries over of water into the clean oil outlet.一个太小的分离盘会导致分离效果差，还会造成净油口出水。
During separation, the basic problem in treating lube oil in purifiers is the gravity disc. 在分离润滑油过程中，主要问题是重力环的选择。The interface position will move into the disc stack if the temperature increases or if the flow rate, density or viscosity decrease.如果温度升高或者流量、密度、粘度降低，分离界面都会移向分离盘， Should the interface enter the disc stack water will escape with the cleaned oil into the oil outlet. 如果分离界面进入分离盘片，将会造成出油口跑水The interface position will move towards the periphery if the temperature decreases or if the flow rate, density or viscosity increase. 如果温度降低或者流量、密度、粘度升高，分离界面将会向外边缘移动。Should the interface reach the outside of the top disc a broken water seal will occur, with consequent oil loss checking and fitting the gravity disc is a time-consuming and unpleasant task. 如果分界面到了盖盘的外面，那么水封就会被破坏，就会跑油，检查更换重力环是一个耗时费力的工作。Since the correct gravity disc is defined as the largest disc that does not cause a broken water seal, it can be a frustrating trial-and-error process. 正确的重力环是一个不破坏水封的最大的环，找出正确的重力环是一个麻烦的试凑过程。Alarm for broken water seals can be frequent.经常会出现水封破坏报警， Consequently, the gravity disc selected mot to be big enough and there is a risk that the oil is not adequately cleaned. 因此重力环不要选择太大，但是也有一个油不能充分净化的问题。Oil losses are reduced by addition of displacement water to the separator bowl prior to a sludge discharge.（排渣）跑油可以通过在排渣过程之前向分离桶额外供入一些置换水得到减轻 This pushes the interface into the disc stack, and increases the volume of water in the bowl.这时分界面向分离盘内部移动，分离桶内部水的体积增加。 Sludge that has not settled in the sludge space will enter the disc stack, and deposits might be formed on the discs.没有在泥渣空间沉下来的泥渣也进入分离盘片，就有可能在分离盘片上沉淀下来。
With a total discharge type purifier large oil losses occur on sludge discharge. 全排放型分油机会在排渣过程中造成大量跑油。The entire contents of the separator bowl are emptied, including not only sludge and separated water but also the oil between the water layer and the centre of the bowl.整个分离桶内部是空的，不仅包括泥渣和分离出来的水也包括水层和分离桶中心之间的油。 It is impossible to have full displacement of the oil in the bowl without water escaping with the cleaned oil, hence the oil loss with total discharge. 不可能在没有一点水从出油口流出的情况下，完全把分离桶内部的油置换出去，所以全排放情况下总会跑油。With a partial discharge type purifier there are virtually no oil losses. 实际上部分排放型分油机不会跑油。The bowl is opened for a shorter period of time, in this type to permit only sludge and water to be discharged.分离桶只开启很短的时间，这种型号的分油机只允许排放泥渣和水。
LESSON 7
Sea Water System 海水系统
Problems are often encountered in sea water systems due to corrosion and erosion phenomena. 由于腐蚀和侵蚀现象使海水系统面临很多问题。These problems arise due to the inherent aggressive chemical nature of sea water or due to the abrasive nature of solids carried in the water causing erosion, or even blockage of passage ways by large agglomerations of biological material, seaweed, shell fish, etc. 这些问题的出现是由于海水内在的化学侵蚀性或者海水中携带的磨蚀性的固体所造成的冲蚀，或者是一些通路被一些生物、海草贝类等的结块所堵塞。System features that require special consideration in view of the above factors are discussed and may be categorized as follows. 对于以上讨论过的因素系统特性要求进行特别考虑，可分类如下：
Sea water strainers 海水过滤器
An incorrect choice of mesh size for the main sea water strainers will frequently give rise to problems of either choking or allowing the passage of excessively large particles into the ship's system.主海水滤器网孔规格的选择不正确会经常导致问题出现，或者是堵塞或者是让特别大的颗粒物质通过，进入船舶系统。
In performing its designed function the sea water strainer will obviously collect material at a rate depending on the degree of contamination of the salt water surrounding the ship. 按照设计功能，海水滤器能够依据船舶周围海水的污染程度，以一定的速率有效地过滤海水中存在的物质，The cleaning of filters must be part of a regular routine and not a chore resorted to when problems occur. 海水滤器的清洁必须是一项常规性的工作，不应该是当问题发生时的临时工作。The frequency of cleaning can only be determined in relation to a particular ship and its duty, but even when a routine is established abnormal conditions may well result in the need for more frequent cleaning.清洁的频率和具体的工作只能由各个船舶决定，即使制定一个惯例，一些不正常的条件出现后也需要加大清洁频率。 Distribution pipework 分配管路
In many cases a single pump is used to supply a number of auxiliary sets and in this case distribution pipework will be used, possibly in the form of a ring main, to supply the various auxiliary sets. 在很多情况下，一台泵用来给很多辅助设备服务，这时会用到分配管路（有可能是环形管路）来供给各种辅助设备。The danger points here are sudden changes in section or direction where erosion damage may occur, and at any necking down of the pipe, for example where the furthermost engine is taken from the main supply rail, where agglomerations of weed, etc. may well occur. 在一些截面或者方向突然改变的危险点会出现侵蚀破坏，在管路的颈缩处海草等就容易结块聚集，如最远处的机械从主供给管路引支管处。At every opportunity inspection and attention should be given to these specific areas.在任何检查的时候，应该注意这些特殊的区域。
Galvanic corrosion 电流腐蚀
It must always be recognized that any two dissimilar material immersed in a high conductivity electrolyte, i.e. sea water, forms a galvanic cell. 必须认识到，任何两种不相似的物质浸在高导电性的电解液中（如海水）都会形成原电池。Such a cell will result in rapid attack of the less noble material (anode) transferring material in the form of neutral salts to the more noble cathode.这样的原电池会使惰性材料（阳极）迅速受到腐蚀，以中性盐的形式向更加惰性的阴极转移物质。 This principle is used to advantage where, for example, zinc rods are used sacrificially to protect heat exchanger headers, or even the ship‘s hull itself.这个原理可以有效利
用，如用牺牲锌棒来保护热交换器盖，或者是保护船体。
In some cases, manufacturers deliberately incorporate less noble materials in order to ensure that the more critical areas are preferentially protected. 一些情况下，生产厂故意混合一些低惰性材料，以使得更加重要的区域到优先保护。A good example is where copper nickel heat exchanger tubes benefit from the proximity of iron pipework or headers.一个很好的例子是铜镍热交换器管从附近的铁管或端盖得到保护。 It is important that the effect of such protection is not excessive to the extent that the life of the sacrificial end is uneconomic.重要的是这样的保护效果不能太过度消耗牺牲级的使用寿命，这样是不经济的。 Where dissimilar metals are used some relief may be given by insulating the dissimilar metals by gaskets and bolt sleeves.这种不相似金属可以通过衬垫或套筒把这两种金属绝缘隔开，使它们的原电池现象减轻。The next step is perhaps to coat the inside surfaces of the less noble element with epoxy paint or nylon. 接下来可能是把低惰性原件用环氧树脂漆或者尼龙包起来。However, the process carries two dangers in that the protection given to the remainder of the circuit is lost, and the smallest defect in the coating is immediately the focus of intensive local attack-the smallest pin-hole in the coating will lead to rapid penetration. 然而，这个过程也包含着两个危险，一旦电路一部分的保护失效，在保护层上很小的损坏就会立即形成强烈的局部集中侵蚀，保护层上很小的孔洞很快就刺穿。In these circumstances, therefore, the safest answer is to install sacrificial anodes. 这种情况，最安全的做法是安装牺牲阳极。It should be noted that efficient electrical contact must be made between the anode and the element it is required to protect, as in this case an active cell is required to be formed.需要注意的是在阳极和被保护的原件之间要有有效地电连接，这样起作用的原电池就形成了。
Sea water pump 海水泵
The most frequent problems with salt water pumps are erosion or cavitation damage to the impeller, corrosion to internals and damage or wear to the rotating seal element.海水泵最容易发生的问题是叶轮的冲蚀和穴蚀、内部的腐蚀及旋转密封部件的损坏和磨损。 Heat exchanger headers 热交换器端盖
The headers of heat exchangers form a natural collecting point for all kinds of debris passing through the salt water system, due to the reduction in flow velocity which occurs within them. 热交换器端盖可以形成一个自然收集点，收集各种通过海水系统的碎片This in turn leads to blockage of the lower tubes by sand, weed, etc. and can also lead to increased local velocities at the inlets to the tubes causing curing of the tube ends due to turbulence.这样就导致了热交换器下部的管子被沙子、海草等堵住，进而使管子入口速度增加,由于湍流使管子端部产生穴蚀。 Heat exchanger 热交换器
Heat exchanger tubes are frequently attacked by sea water because of turbulence within the tubes causing pitting and eventual leakage.由于管内部海水的湍流，热交换器的管子经常受到海水的侵蚀，在管子上造成麻点最后漏泄。 Alternatively, a build-up of corrosion products may cause a local turbulence, leading to eventual local pitting. 或者是，出现腐蚀导致局部湍流，最后出现麻点蚀斑。A general build-up of deposits resulting a loss of thermal efficiency and leads in turn to overheating problems. 出现一个普通的沉淀，就会导致热效率降低，进而导致过热问题。Regular cleaning will extend the life of heat exchanger tubes considerably.定期清理会相当程度的延长热交换器的寿命。
It is not possible, for the operator to control the corrosive nature of sea water but the two main subsidiary causes, flow velocity and entrained solids are within the control of the operator to a greater or lesser extent. 对于一个使用者不可能控制海水的腐蚀性，但是另两个次要原因，