第一部分一热力学工程基础知识

1、WELCOME ！ 热力工程基础知识Foundation knowledge of thermal engineering 热力参数名称，计量单位及符号：Thermodynamic parameter name,unit and mark:名称name符号mark单位unit温度 temperatureT压力 pressureP Pa、KPa、MPa比体积 specific volumem/kg能 energyEJ、KJ功 workWKJ/Kg热量 quantity of heatQKJ比热容 specific heat capacitycKJ/(KgK) 真空、真空度(vaucum、vacu

2、um degree)当容器中的压力低于大气压力（atmospheric pressure）时，把低于大气压力的部分叫真空。用符号“pv”表示。其关系式为： 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 发电厂有时用百分数表示真空值的大小，称为真空度。真空度是真空值和大气压力比值的百分

3、数， 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% 什么是表压力？What is gauge pressure？当容器中的压力高于大气压力时，把

4、高于大气压力的部分称为表压力。用符号“pe”表示。其关系式为：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 什么是经济真空（economic vacuum）？什么是极限真空（ultimate v

5、acuum）？ What is the economic vacuum?What is the ultimate vacuum?所谓经济真空是提高真空使汽轮发电机增加的负荷与循环水泵多消耗的电功率之差为最大时的真空。Economic vacuum is vacuum that when the difference between the load of turbine generator and consumed electrical power of circulating pumps is maximum. 如真空再继续提高,由于汽轮机末级喷嘴的膨胀能力已达极限,汽轮机的功率不再增加,此

6、时真空称为极限真空。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. 朗肯循环（Rankine cycle） 以水蒸气为工质的火力发电厂中，让饱和蒸汽在锅炉的过热器中进一步吸热，然后过热蒸汽在汽轮机内进行绝热膨胀做功，汽轮机排汽在凝汽器中全部凝结成水。并以

7、水泵代替卡诺循环中的压缩机使凝结水重又进入锅炉受热，这样组成的汽-水基本循环，称之为朗肯循环。 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. 朗肯循环是通过哪些热力设备实施的？各设备的作用是什么？画出其热力设备系统图。Rankine cycle is implemented by which thermal equipment? What is the role

9、of the each device? Draw its thermal equipment system diagram.朗肯循环的主要设备是蒸汽锅炉、汽轮机、凝汽器和给水泵四个部分。The main equipments of the Rankine cycle are the steam boiler, steam turbine, condenser and feed pump.锅炉：包括省煤器、炉膛、水冷壁和过热器，其作用是将给水定压加热，产生过热蒸汽，通过蒸汽管道，送入汽轮机。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. 汽轮机：蒸汽进入汽轮机绝热膨胀做功将热能转变为机械能。 Turbine: The steam proceeds to the turbine to do adiabatic expansion work and convert heat energy into mechanical energy

11、.凝汽器：作用是将汽轮机排汽定压下冷却，凝结成饱和水，即凝结水。 Condenser: cooling the turbine exhaust steam with certain pressure and condenses into water-saturated, i.e., the condensate water.给水泵：作用是将凝结水在水泵中绝热压缩，提升压力后送回锅炉。 Feed pump: adiabatic compression of condensate water in pump, feed back in boiler after raising the pressu

12、re.朗肯循环热力设备系统图 System diagram of Rankine cycle thermal equipmentCondenser TurbineFeedwater pump Boiler Generator 朗肯循环Rankine cycleFeedwater pumpCondenserTurbineBoiler 给水回热循环定义及意义?What is the extraction cycle of feedwater ?What is the meaning of using it?把汽轮机中部分做过功的蒸汽抽出，送入加热器中加热给水，这种循环叫给水回热循环。 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. 给水回热循环的意义是什么？ What is the meaning of extraction cycle of feedwater？ 采用给水回热加热以后，一方面从汽轮机中间部分抽出一部分蒸汽，加热给水提高了锅炉给水温度。这样可使抽汽不在凝汽器中冷凝放热，减少了冷源损失。另一方面，提高了给水温度，减少给水在锅炉中的吸热量。 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. 什么是换热？基本形式有哪几种？ What is heat transfer? How many basic forms are there?物体间的热量交换称为换热。The heat exchange between the objects called heat transfer.换热有三种基本形式： There are three basic forms:导热conduction：直接接

16、触的物体或物体本身各部之间的热量传递现象。常见的导热现象如管壁、汽缸壁、汽包壁内外表面间的热量传递。 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、对流换热convective heat transfer：在流体内，热量由热流体传递给冷流体。例如汽机排汽对凝汽器铜管；循环水对铜管；空气对暖器等。 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. 热辐射radiation heat transfer：辐射换热是一种不需要物质直接接触而进行的热量传递方式。如火电厂中,炉膛内火焰与水冷壁间的换热。 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？它分为哪两种形式？What is vaporization? Which two forms is it divided?物质从液态变成汽态的过程叫汽化。它分为蒸发和沸腾两种形式。The process of substances from the liquid to vapor phase is called va

20、porization. It is divided into evaporation and boiling. 液体表面在任何温度下进行的比较缓慢的汽化现象叫蒸发。The slow vaporization on liquid surface at any temperature is called evaporation.液体表面和内部同时进行的剧烈的汽化现象叫沸腾。The intense vaporization phenomenon is in the process on liquid surface and interior at the same time is called bo

21、iling. 什么是凝结？有什么特点？What is condensation? What are the characteristics of vapor condensation?物质从汽态变成液态的现象成为凝结。The phenomenon from steam state to liquid of substances called condensation.特点characteristic：a、一定压力对应一定温度。Certain pressure corresponding certain temperature.b、温度不变。Constant temperature. 什么是湿饱

22、和蒸汽，干饱和蒸汽，过热蒸汽？What is wet saturated steam、dry saturated steam and superheated steam/vapor？含有饱合水的蒸汽即为湿饱和蒸汽，简称湿蒸汽。 The vapor containing saturated water before the water is not completely vaporized is called the wet saturated steam, referred to as wet steam.湿蒸汽继续定压加热，水完全汽化成蒸汽的状态，即为干饱和蒸汽。 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. 干饱和蒸汽继续定压加热，蒸汽温度上升超过饱和温度时，即为过热蒸汽。 Continue to heat with constant pressure, steam temperature increases and exceed the saturated steam temperature, dry saturated steam is converted into superheated steam.电厂整个工艺流程:Total technological process of power plant 原水经过化水车间处理后成为合格的软化水，软化水输送到汽机车间经除氧、加热经给水泵输送到锅炉内，经吸热后变成压力、温度合格蒸汽，蒸汽再被输送到汽轮机内，蒸汽冲动汽轮机转子转动，汽轮机通过联轴器带动发电机转动，发电机通过电磁感应进行发电，经过变压器输送到电网；蒸汽最后在凝汽器内凝结