Lesson-18-Maintenance-Procedures-for-Reciprocating-Air-Compressors.doc

Lesson 18 Maintenance Procedures for Reciprocating Air Compressors第18课往复式空压机的维护保养1. Since marine compressors are encountered in several forms, comments on maintenance will be made by following the passages through each form of machines.1.由于船用空压机有多种形式，下文将通过介绍不同形式的机型来探讨空压机的维护保养工作。Air Filter空气滤器2. The dry type of filter, as used on marine compressors, has a filtering media of either felted cloth or paper, the latter usually being slightly oil coated. This type of filter is quite satisfactory although its strength is sometimes suspect on higher speed machines. The most widely used type of filter is the viscous impingement type filter, usually of cylindrical design and the filtering media usually being woven copper wire or nylon strands, which are, when cleaned, dipped in oil and allowed to drain before fitting. The oil coating then traps the dirt quite satisfactorily, since the atmosphere for the marine compressor is usually fairly clean. This type of filter is also quite acceptable for oil-free machines, if the unit is being used for controlling air. First stage failures have, on occasions, been caused by some of the copper wire being teased loose and the pulsating air flow bending the strands backwards and forwards until a strand has broken free and lodged awkwardly in either a valve or piston clearance. In general, the nylon strand is much more resilient in this respect. It is essential that the filter is kept in a clean condition so that the air pressure drop across the filter is kept to an absolute minimum, and the engineer in charge of the compressors should accept as his responsibility the blanking off of the air inlet before any painting takes place, as should this area be painted it will cause too great a pressure drop. This point is well worth inspecting after any painting in the compressor vicinity.2.船用空压机使用的干式过滤器，其过滤介质是毡布或纸，后者通常轻微涂油。最常用的滤器为黏滞撞击型滤尘器，通常为圆柱状，滤网为铜网或尼龙绳，当清洗时要浸泡在油里，而且安装前要放残。由于对船用空压机来说空气相当干净，所以油膜能很好地吸附污垢。如果是控制空气的单元，这种滤器也可以用于无润滑机器。有时，一级故障是因为铜丝松弛，而且空气使得铜丝前后弯曲直到铜丝断裂或在气阀活塞间隙中无规律运动。通常尼龙丝回弹力较大。尽量将滤器放置在干净的环境是很有必要的，这样经过滤器的空气可以保持在最小值。并且主管空压机的轮机员把涂油漆前密封滤器进气口视为自己的职责，如果进口有油漆会产生很大的压降，空压机附近的任何油漆作业结束后，这一点都是值得检查的。First Stage Valves一级气阀3. All modern marine compressors use automatic valves which operate on low pressure differential. It is usual for the suction valve to have a lower spring pressure than the delivery valve and it is, therefore, most important that whenever a valve is stripped for cleaning and/ or maintenance, the parts are put back correctly and even if springs look similar, that no interchange between suction and delivery valves is made. When selecting spare springs or plates from the Spares Inventory, care must be taken that the right part is selected. The valve is the heart of the machine and, since it operates once every revolution, the valve movements are extremely frequent and, because of this, the valve lifts are kept extremely low to reduce impact forces. The spring assembly design is very critical to ensure correct valve action. It is extremely important, therefore, that the valve design is not altered in any way without contacting the compressor manufacturer. Valve failure will occur due to wear and fatigue, and is a function of the compressor design; therefore, if failures occur from this facet on a frequent basis, it is almost certainly due to the wrong machine selection, or if on a lubricated machine, to insufficient oil carry-over. Naturally, if the compressor is overheating wear and fatigue will occur.3.所有的船用空压机都使用在低压差下操作的自动阀。通常吸入阀的弹簧压力低于排气阀。因此最为重要的是，无论何时因清洁或维护拆检气阀后，所有的零件要准确放回。即使吸入阀和排出阀弹簧很相似，也不能互换。当从备件单选用备用弹簧或阀盘时，必须确保选择正确。气阀是机器的心脏。由于它每转动一次，运动非常频繁，气阀升程很低来降低冲击力。弹簧组件的设计对确保正确的阀门动作是非常重要的。这是非常重要的，因此，无需与空压机制造商协商，阀门的设计无论如何是不能改变的。阀的故障是由于损耗，而且也是空压机设计的功能之一;如果这种故障经常发生，那么几乎可以肯定是由于机器选择不当，如果发生在有滑油的空压机上，则是由于滑油不够。通常，如果空压机过热，磨损和疲劳就会发生。4. Failures will also occur due to the presence of foreign particles. If these are of a solid nature they are, normally, quite readily detected, since they will also usually affect other running parts. However, if in liquid form, this liquid is either being drawn into the machine or, in the case of non-oil free machines, is caused by excessive oil coming past worn pistons and rings.4.外来微粒也会导致故障出现。通常，固体颗粒很容易被发现，因为它们也会影响其他运动部件。然而，如果是液体，液体要么进人机器，要么在有滑油的空压机中，过多的油从磨损的活塞或环槽中流出。5. Carbon deposits from the oil also cause valve wear and breakages, and it is, therefore, important that the compression chambers and oil usage are carefully examined. On all non-oil free machines some carboning of valves will usually take place but, providing the valves are not-found excessively carbonned when maintenance is carried out to the manufacturers recommendations, the problem can be accepted as normal. It is usual for the suction valve to be relatively free from carbon except on its bore contact side, where the carbon deposits should be fairly low, but the delivery valve will usually carbon up on both its inner and outer surfaces, since the air stream through the valve is hot and contaminated by the lubricating oils, except, of course, on oil free machines.5.滑油积炭也会导致气阀磨损和断裂。因.此，要仔细检查压缩室和滑油。有滑油的空压机经常出现气阀结炭。但是，当根据制造商的要求进行维护，气阀没有发现过多积炭，被认为是正常的。吸如入阀除了在阀孔接触面之外几乎没有积炭，在此处积炭很少，但是排出阀会有积炭出现在内、外面，因为有热的气流经过，而且被滑油污染，当然无滑油的机型除外。6. Valves should be removed, dismantled and inspected at frequent intervals, as recommended by the compressor manufacturer. Depending on the condition of the valves, the intervals between inspections can be reduced or extended, providing worn parts can be replaced before failure. In the event of a broken valve being found, all the parts should be located, otherwise they might cause damage to other parts of the machine. Air valve parts should be carefully and thoroughly cleaned with a cleansing fluid, using a soft brush. Sharp edged tools and wire brushes should never be used to clean valve seats and plates. Any parts which are worn, damaged or cracked must be replaced. Valve plates which are worn on one side should never be turned over and used. To ensure good sealing between valve seat and plate, each part should be lightly lapped, separately, on a smooth flat surface. After valves have been reassembled, check by using a small piece of wood that the plates are free to move and will fully open. Valves are usually seated in the cylinder either by metal to metal contact or using a gasket. The former should be lapped together if there are signs of dents, nicks or scratches, to provide a leak-proof joint. In the case of gaskets it is best to fit new parts each time valves are inspected. When replacing the valves in the cylinder, special care should be taken to ensure that the suction and delivery valves are installed in their respective ports and that the correct clearance is maintained between the valves and pistons.6.气阀应该根据空压机制造商的建议，定期进行拆卸、清洁、检查。检查间隔可以根据气阀的状况缩短或延长，使得受损部件能在失效前更换。发现气阀破损，查找出所有的(破损)部件，否则会导致其他部件损坏。空气阀件应仔细和彻底地用清洁液和软刷清洗。不允许用利器或钢丝刷清理阀座或阀盘。任何部件已磨损、损坏或破裂，必须更换。一侧已磨损的阀板不应该换向使用。为了确保阀座阀盘之间良好的密封，每个部分应分别在光滑平整的表面轻轻研磨。阀门重新组装后，用木片检查阀盘是否可以自由移动、全开。气阀通过金属与金属接触戴使用衬垫安装在气缸内。如果有迹象表明存在凹痕、缺口或刮痕，金属应该叠放来防漏。使用衬垫的话，最好气阀每次检查都更换衬垫。当更换缸体的阀时，要特别小心确保吸入阀和排出阀安装在相应的孔上，阀与活塞之间要保持适当的间隙。First Stage Intercooler一级冷却器7. Intercoolers usually cause very little problem providing the water side of the tubes is kept free of fouling. On the air side, if the machine is correctly cooled and there have been no excessive temperatures caused by valve failures, etc. it should be relatively clean with only oil smear present. If excessive temperatures have been present, it will often be found that the delivery valve, although showing signs of heat, is relatively free from carbon, but the cooler inlet is heavily carboned on its immediate entrance. This carbon will sometimes also affect the relief valve, so carboning in this area is a defect that must be treated very seriously and the cooling of the machine investigated. The function of the intercooler is to reduce the air temperature to as low a figure as possible before proceeding to the next stage, and in doing this it brings the air below its dew point and condensate is collected at the outlet end of the cooler. It is extremely important that this condensate is kept drained from the machine, preferably by an automatic drain; Alternatively by a partially opened drain valve. The seating of a drain valve which is partially open will quickly be damaged by wire drawing and cause maintenance problems. Manual blow down at frequent intervals, say every half to one hour, is not normally possible under present day operating conditions.7.如果供水管侧保持无结垢，中间冷却器就会很少出问题。在空气侧，如果机器正确冷却，就不会产生阀件故障导致的高温等。它应该相对干净，仅有少量油污。如果温度过高，通常排出阀发热但是没有积炭，冷却器进口严重积炭。这种炭有时还会影响安全阀，所以，这个区域出现积炭是严重缺陷，必须认真对待，检查机器冷却。中间冷却器的功能是，在空气进人下一级前尽可能降低其温度。这样空气温度在露点以下，冷凝水被收集在冷却器的出口端。凝水排出机器是极为重要的。优选自动泄放阀，也可部分地打开泄放阀。部分打开的泄放阀的阀座会由于节流很快损坏，会引起维护问题。频繁地手动排凝水，比如每半个小时到一个小时，在目前的运行状况下根本不可能。Second Stage Valves二级气阀8. The configuration of these valves is identical to the first stage valves, except they are usually smaller, since the air is reduced in volume due to it having been compressed in the first stage, and also the scantlings are usually heavier since the stage pressure to be withstood is higher. Maintenance should be carried out in a similar manner, and at the same intervals as the first stage valves.After Cooler and Fusible Plug8.这些阀的结构与一级阀相同，但是它们比较小。因为空气在第一阶段中被压缩，体积减小，并且材料也比较重，因为要承受更高的级间压力。维护应该以类似的方式进行，并与一级阀间隔时间相同。After Cooler and Fusible Plug后冷却器及易熔塞9. The comments on the intercooler are applicable to the after cooler, but since the pressures are higher and usually the inlet temperatures are also higher, the cleanliness of this cooler is more critical from a safety point of view. It should be noted, however, that this cooler has absolutely no bearing on the compressor performance since its action takes place after all work has been done on the air, and its function is to bring the delivery temperature to a reasonable figure and, in doing so, remove condensate from the air.9.对于中间冷却器的说明也适用于后冷却器。但由于压力较高，通常后冷却器的入口温度也较高，从安全的角度来看，冷却器的清洁是更关键的。然而，应当指出，该冷却器对压缩机的性能完全没有影响，因为它的动作发生在对空气所有的工作已经完成之后。它的功能是，通过使排气温度到一个合理的数字，除去空气中的凝水。10. Although all marine compressors usually have a fusible plug fitted immediately on the outlet of the after cooler to meet Classification Society regulations, this fusible plug does not contribute to machine safety in any way whatever, but only to the safety of the system after the machines outlet.10.虽然所有船用空压机在后空冷器出口处都安装有易熔塞来满足船级社的法规要求，这种易熔塞不会以任何方式有助于机器的安全，只会有助于出口处的系统安全。B. Multiple Choice选择题Questions 1-3 are based on paragraphs 1-2. 根据课文第1-2段回答问题1-3.1. Which air filters are most commonly used on board ships? 船上最常用的滤器是哪一种?答案.DA. Cell type. 蜂窝式B. Oil bath type油浸式.C. Dry type of filter. 干式滤器D. Viscous impingement type filter黏滞撞击型滤尘器.2. _is used on marine compressors and quite satisfactory although its strengthis suspected on higher speed machine.被用在船用压缩机上并且效果令人满意，虽.然在高速机上它的强度值得怀疑。答案:CA. Viscous impingement type filter黏滞撞击型滤尘器B. Automatic viscous-impingement intake air filter自动黏滞撞击型滤尘器C. Dry type of filter with felted paper纸质干式过滤器D. Dry type of filter with felted cloth毡布干式过滤器3. The maintenance procedure of viscous impingement type filter is the following except下列是黏滞撞击型滤尘器的维护步骤，除了_。答案AA. to trap the dirt收集灰尘B. to dip in oil when cleaned清洗时要浸泡在油里C. to drain before fitting .安装前要放残D. to keep in a clean condition保持清洁状态Questions 4-6 are based on paragraphs 3-6根据课文第3 -6段回答问题4-6。4. The selection of spare spring in suction valve and delivery valve of first stage must be very careful because_.选择一级吸排气阀的备用弹簧必须谨慎，因为_答案:AA. the valve design is often altered阀的设计经常变化B. it is usual for the suction valve to have a lower spring pressure than the delivery通常吸入阀弹簧的压力低于排出阀C. the valve operates once every revolution, the valve movements are extremely frequent气阀每转动作一次，气阀的运动特别频繁D. if the compressor is overheating wear and fatigue will occur如果空压机过热，会出现磨损和疲劳5. Carbon deposits from the oil will cause valve wear and breakages so_should be carried out. 滑油带来的积炭会导致阀磨损和破坏，所以应该_。答案.BA. check for the presence of foreign particles检查是否出现外来杂质B. compression chamber and oil usage are carefully examined仔细检查压缩室和滑油C. check for the excessive oil coming past worn pistons and rings过多的滑油从活塞环溢出D. check for the insufficient oil of lubricated machine机器滑油不足6. Air valve parts should be_.气阀部件应该_。答案CA. cleaned by sharp edged tools and wire brush用利器和钢丝刷清洁B. removed, dismantled and inspected at fixed intervals定期拆解检查C. carefully and thoroughly cleaned with a cleansing fluid用清洁剂仔细彻底地清洁D. checked by using a small piece of wood用一片小木片检查Questions 7-10 are based on paragraphs 7-10. 根据课文第7-10段回答问题7 -9.7. The function of the intercooler is to_级间冷却器的作用是_。答案BA. increase the air temperature to as high a figure as possible before proceeding to the next stage在进人下一级前尽可能地提高空气温度B. reduce the air temperature to as low a figure as possible before proceeding to the next stage在进入下一级前尽可能地降低空气温度C. bring the air above its dew point .使空气温度低于露点D. condensate the air at the outlet end of the cooler在冷却器出口端形成冷凝8. In the sentence” The configuration of these valves is identical to the first stage valves, except they are usually smaller”, the word “identical” has the same meaning with_.在句子“这些阀的结构与一级阀是相同的，但是它们比较小”中，“相同的”与_意思一致。答案.BA. different不同的B. same一样的C. obvious明显的D. exclusive独有的9. Of the following statements about the fusible plug, which one is true? 关于易熔塞的叙述，下列哪一项是正确的?答案;BA. This fusible plug is not necessary for the safety of the machine. 为了机器的安全易熔塞不是必需的。B. This fusible plug only contributes to the safety of the system after the machines outlet. 易熔塞只有助于出口处的系统安全。C. Most marine compressors usually have a fusible plug fitted immediately on the outlet of the after cooler. 大部分船用空压机在后空冷器出口处都安装有易熔塞。D. The installation of the fusible plug is to meet the national regulation.易熔塞的安装要符合国家法规Task 2 Vocabulary and Structure任务2词汇与结构A. Technical Terms专业术语Translate the following into