第一部分一熱力學(xué)工程基礎(chǔ)知識(shí)

1、WELCOME ！ 熱力工程基礎(chǔ)知識(shí)Foundation knowledge of thermal engineering 熱力參數(shù)名稱，計(jì)量單位及符號(hào)：Thermodynamic parameter name,unit and mark:名稱name符號(hào)mark單位unit溫度 temperatureT壓力 pressureP Pa、KPa、MPa比體積 specific volumem/kg能 energyEJ、KJ功 workWKJ/Kg熱量 quantity of heatQKJ比熱容 specific heat capacitycKJ/(KgK) 真空、真空度(vaucum、vacu

2、um degree)當(dāng)容器中的壓力低于大氣壓力（atmospheric pressure）時(shí)，把低于大氣壓力的部分叫真空。用符號(hào)“pv”表示。其關(guān)系式為： When the pressure in the container below the atmospheric pressure. The part lower than atmospheric pressure is called the vacuum. Use the symbol Pv. Their relationship is: PvPatmPa 發(fā)電廠有時(shí)用百分?jǐn)?shù)表示真空值的大小，稱為真空度。真空度是真空值和大氣壓力比值的百分

3、數(shù)， 即： The power plant express the size of the vacuum value as a percentage sometimes, called the degree of vacuum. The degree of vacuum is the ration percentage of the vacuum value and the atmospheric pressure, namely: 真空度(degree of vacuum)Pv / Patm100% 什么是表壓力？What is gauge pressure？當(dāng)容器中的壓力高于大氣壓力時(shí)，把

4、高于大氣壓力的部分稱為表壓力。用符號(hào)“pe”表示。其關(guān)系式為：When the pressure in the container exceed the atmosphere pressure, the part higher than atmosphere pressure is called the gauge pressure. Use the symbol pe .There relationship is: pepatm + pa PvPatmPe0PaPaPe=Pa-PatmPv=Patm-Pa 什么是經(jīng)濟(jì)真空（economic vacuum）？什么是極限真空（ultimate v

5、acuum）？ What is the economic vacuum?What is the ultimate vacuum?所謂經(jīng)濟(jì)真空是提高真空使汽輪發(fā)電機(jī)增加的負(fù)荷與循環(huán)水泵多消耗的電功率之差為最大時(shí)的真空。Economic vacuum is vacuum that when the difference between the load of turbine generator and consumed electrical power of circulating pumps is maximum. 如真空再繼續(xù)提高,由于汽輪機(jī)末級(jí)噴嘴的膨脹能力已達(dá)極限,汽輪機(jī)的功率不再增加,此

6、時(shí)真空稱為極限真空。If continue to raise vacuum, due to the expansion capacity of end level nozzle of the turbine has reached the limit, no further increase for turbine power, the vacuum known as the ultimate vacuum. 朗肯循環(huán)（Rankine cycle） 以水蒸氣為工質(zhì)的火力發(fā)電廠中，讓飽和蒸汽在鍋爐的過熱器中進(jìn)一步吸熱，然后過熱蒸汽在汽輪機(jī)內(nèi)進(jìn)行絕熱膨脹做功，汽輪機(jī)排汽在凝汽器中全部凝結(jié)成水。并以

7、水泵代替卡諾循環(huán)中的壓縮機(jī)使凝結(jié)水重又進(jìn)入鍋爐受熱，這樣組成的汽-水基本循環(huán)，稱之為朗肯循環(huán)。 In the steam power plant using steam as the working medium, saturated steam proceeds to the boiler superheater for further heat absorption, and superheated steam do adiabatic expansion work in the turbine, the exhausting steam of turbine condenses into

8、 water in the condenser. The condensate water proceeds to boiler again to be heated by pump instead of compressor in Carnot cycle, so this steam - water cycle, known as the Rankine cycle. 朗肯循環(huán)是通過哪些熱力設(shè)備實(shí)施的？各設(shè)備的作用是什么？畫出其熱力設(shè)備系統(tǒng)圖。Rankine cycle is implemented by which thermal equipment? What is the role

9、of the each device? Draw its thermal equipment system diagram.朗肯循環(huán)的主要設(shè)備是蒸汽鍋爐、汽輪機(jī)、凝汽器和給水泵四個(gè)部分。The main equipments of the Rankine cycle are the steam boiler, steam turbine, condenser and feed pump.鍋爐：包括省煤器、爐膛、水冷壁和過熱器，其作用是將給水定壓加熱，產(chǎn)生過熱蒸汽，通過蒸汽管道，送入汽輪機(jī)。Boilers: include economizer, furnace, water wall and

10、superheater, and its role is heating and pressurizing the feed water to generate superheated steam and feed it into the turbine through the steam pipe. 汽輪機(jī)：蒸汽進(jìn)入汽輪機(jī)絕熱膨脹做功將熱能轉(zhuǎn)變?yōu)闄C(jī)械能。 Turbine: The steam proceeds to the turbine to do adiabatic expansion work and convert heat energy into mechanical energy

11、.凝汽器：作用是將汽輪機(jī)排汽定壓下冷卻，凝結(jié)成飽和水，即凝結(jié)水。 Condenser: cooling the turbine exhaust steam with certain pressure and condenses into water-saturated, i.e., the condensate water.給水泵：作用是將凝結(jié)水在水泵中絕熱壓縮，提升壓力后送回鍋爐。 Feed pump: adiabatic compression of condensate water in pump, feed back in boiler after raising the pressu

12、re.朗肯循環(huán)熱力設(shè)備系統(tǒng)圖 System diagram of Rankine cycle thermal equipmentCondenser TurbineFeedwater pump Boiler Generator 朗肯循環(huán)Rankine cycleFeedwater pumpCondenserTurbineBoiler 給水回?zé)嵫h(huán)定義及意義?What is the extraction cycle of feedwater ?What is the meaning of using it?把汽輪機(jī)中部分做過功的蒸汽抽出，送入加熱器中加熱給水，這種循環(huán)叫給水回?zé)嵫h(huán)。 Extrac

13、t the steam done work from turbine; feed into heater for heating feed water, this cycle is called the extraction cycle of feedwater. 給水回?zé)嵫h(huán)的意義是什么？ What is the meaning of extraction cycle of feedwater？ 采用給水回?zé)峒訜嵋院?，一方面從汽輪機(jī)中間部分抽出一部分蒸汽，加熱給水提高了鍋爐給水溫度。這樣可使抽汽不在凝汽器中冷凝放熱，減少了冷源損失。另一方面，提高了給水溫度，減少給水在鍋爐中的吸熱量。 Usi

14、ng the feedwater extraction cycle to heat, on the one hand, to take part of the steam from the middle part of turbine to heat feedwater for increasing feedwaters temperature. This avoids the extraction condensing and discharging heat in the condenser ，and reduces the loss of the cold source. On the

15、other hand, increase feedwater temperature; reduce the heat absorption of the feedwater in the boiler. 什么是換熱？基本形式有哪幾種？ What is heat transfer? How many basic forms are there?物體間的熱量交換稱為換熱。The heat exchange between the objects called heat transfer.換熱有三種基本形式： There are three basic forms:導(dǎo)熱conduction：直接接

16、觸的物體或物體本身各部之間的熱量傳遞現(xiàn)象。常見的導(dǎo)熱現(xiàn)象如管壁、汽缸壁、汽包壁內(nèi)外表面間的熱量傳遞。 The phenomenon of heat transfer from one object to another directly or among parts of object itself called conduction. The conduction phenomena in power plant are between the inner and outer surfaces of wall panels, cylinder walls and drum wall. b.

17、對(duì)流換熱convective heat transfer：在流體內(nèi)，熱量由熱流體傳遞給冷流體。例如汽機(jī)排汽對(duì)凝汽器銅管；循環(huán)水對(duì)銅管；空氣對(duì)暖器等。 The heat transfer between fluids mainly due to the movement of fluid, so that part of the heat of the hot fluid is passed to the cold fluid, this heat transfer method is called convective heat transfer. The convective heat tr

18、ansfer phenomenon in the power plant, such as: exhaust gas to economizer; working medium to water wall; exhaust steam to condenser copper pipe; recycled water to copper pipe; air to radiator. c. 熱輻射radiation heat transfer：輻射換熱是一種不需要物質(zhì)直接接觸而進(jìn)行的熱量傳遞方式。如火電廠中,爐膛內(nèi)火焰與水冷壁間的換熱。 The radiation heat transfer ex

19、change heat without contacting object directly. Such as the heat transfer between the flame and the water wall furnace in power plant. 什么是汽化？它分為哪兩種形式？What is vaporization? Which two forms is it divided?物質(zhì)從液態(tài)變成汽態(tài)的過程叫汽化。它分為蒸發(fā)和沸騰兩種形式。The process of substances from the liquid to vapor phase is called va

20、porization. It is divided into evaporation and boiling. 液體表面在任何溫度下進(jìn)行的比較緩慢的汽化現(xiàn)象叫蒸發(fā)。The slow vaporization on liquid surface at any temperature is called evaporation.液體表面和內(nèi)部同時(shí)進(jìn)行的劇烈的汽化現(xiàn)象叫沸騰。The intense vaporization phenomenon is in the process on liquid surface and interior at the same time is called bo

21、iling. 什么是凝結(jié)？有什么特點(diǎn)？What is condensation? What are the characteristics of vapor condensation?物質(zhì)從汽態(tài)變成液態(tài)的現(xiàn)象成為凝結(jié)。The phenomenon from steam state to liquid of substances called condensation.特點(diǎn)characteristic：a、一定壓力對(duì)應(yīng)一定溫度。Certain pressure corresponding certain temperature.b、溫度不變。Constant temperature. 什么是濕飽

22、和蒸汽，干飽和蒸汽，過熱蒸汽？What is wet saturated steam、dry saturated steam and superheated steam/vapor？含有飽合水的蒸汽即為濕飽和蒸汽，簡稱濕蒸汽。 The vapor containing saturated water before the water is not completely vaporized is called the wet saturated steam, referred to as wet steam.濕蒸汽繼續(xù)定壓加熱，水完全汽化成蒸汽的狀態(tài)，即為干飽和蒸汽。 The wet satur

23、ated steam continue to be heated under constant pressure conditions, the state that water is completely vaporized into steam is called the dry saturated steam. 干飽和蒸汽繼續(xù)定壓加熱，蒸汽溫度上升超過飽和溫度時(shí)，即為過熱蒸汽。 Continue to heat with constant pressure, steam temperature increases and exceed the saturated steam temperature, dry saturated steam is converted into superheated steam.電廠整個(gè)工藝流程:Total technological process of power plant 原水經(jīng)過化水車間處理后成為合格的軟化水，軟化水輸送到汽機(jī)車間經(jīng)除氧、加熱經(jīng)給水泵輸送到鍋爐內(nèi)，經(jīng)吸熱后變成壓力、溫度合格蒸汽，蒸汽再被輸送到汽輪機(jī)內(nèi)，蒸汽沖動(dòng)汽輪機(jī)轉(zhuǎn)子轉(zhuǎn)動(dòng)，汽輪機(jī)通過聯(lián)軸器帶動(dòng)發(fā)電機(jī)轉(zhuǎn)動(dòng)，發(fā)電機(jī)通過電磁感應(yīng)進(jìn)行發(fā)電，經(jīng)過變壓器輸送到電網(wǎng)；蒸汽最后在凝汽器內(nèi)凝結(jié)