輪機(jī)英語(yǔ)教學(xué)課件(16)MarineBoilers

1、Lesson 16 Marine Boilers1. Main Contents of the Text2. Useful Vocabulary & Special Terms3. Detailed Analysis of Difficult Sentences4. Review Questions 5. Some Relevant Multiple Choice ExercisesMain Contents of the TextTypes of boilerFiretube boilers and watertube boilersBoiler mountingsSafety valves

2、Main steam stop valveWater level gaugeWaste heat recovery systemMain Contents of the TextThis unit tells us there are two distinct types of marine boilers,i.e. fire-tube boiler and water-tube boiler.In this unit, we also can learn different functions of two distinct type of marine boilers and their

3、advantages and disadvantages.We also have to pay attention to the basic structures of marine boilers and functions of mountings of a boiler.Useful Vocabulary & Special Terms1. distinct: completely different from 名詞：distinction eg. There are two distinct types of marine boilers in use on board ship.2

4、. mounting: part of a machine (equal to fitting) boiler mountings(fittings) 鍋爐附件3. analyze: 分析 名詞：analysis eg. analysis certificate 化驗(yàn)證書 4. refractory 耐火的，耐熱的 refractory alloy 高熔點(diǎn)合金 refractory brick 耐火磚 refractory casting tube 耐熱鑄管 refractory coating 耐火 涂料， 耐熱層Useful Vocabulary & Special Terms :Defi

5、nition of boilersFire-tube boiler: the hot gases from the furnace pass through the tubes while the water is on the outside. Water-tube boiler: the water through inside of the tubes while the hot furnace gases pass around the outside. Comparison between two types of boilersFunctions:Fire-tube boiler

6、are commonly used with steam reciprocating engines on board ship,but because of their comparatively poor efficiency and low power/weight ratio, these system are no longer installed for propulsion plant. water-tube boiler are used widely on the ship. However,the water-tube boiler require great skill

7、in operating and maintaining.esp.with regard to the purity of the feed water, its upkeep is more expensive than the fire-tube boiler. Comparison between two types of boilersWater-tube boiler has distinct advantage over fire-tube boiler:1.The steam can be raised from cold water in short period of tim

8、e because circulation of the water is natural and immediate on lighting up.2.The steam and water drums are small in diameter compared with the large shell of the fire tube boilers, therefore they are suitable for much higher steam pressure.3.Less mass of water is carried in boiler, hence a saving in

9、 weight and less space is taken up for the same output. Cochran spheroid vertical boilerBoiler Mountings:Safety valves: to protect the boiler against overpressure.Main stem stop valve: usually fitted in the main steam supply line and is usually of the non-return type.Auxiliary stem stop valve: a sma

10、ller valve fitted in the auxiliary steam supply line,and is usually of the non-return valve.Boiler Mountings:Blow down valve: This valve enables water to be blown down or emptied from the boiler.Scum valve: a shallow dish positioned at the normal water level is connected to the scum valve. This enab

11、les the blowing down or removal of scum and impurities from the water surface.Detailed Analysis of Difficult Sentences1 Fire-tube boilers are used for auxiliary purposes to provide smaller quantities of low pressure steam on diesel engine powered ships. 火管鍋爐應(yīng)用于輔助的目的，為柴油機(jī)動(dòng)力船提供少量的低壓蒸汽。 Powered為過(guò)去分詞作前置定語(yǔ)Detailed Analysis of Difficult SentencesGeneration of electric power from a steam turbo-generator and the supply of saturated steam(飽合蒸汽) to heating services by exhaust gas heat recovery systems is effected in many ships. 在許多船上通過(guò)廢熱回收裝置由蒸汽渦輪發(fā)動(dòng)機(jī)發(fā)電和向加熱設(shè)備供應(yīng)飽和蒸汽均有應(yīng)用。該句為主系表結(jié)構(gòu)，is之前皆為主語(yǔ)。Review Qu