发电方式浅析--电气工程概论论文

发电方式浅析

摘要：发电是生产电能的核心，担负着把不同种类的一次能源转换成电能的任务。依据使用的能源来源的不同，发电厂可分为许多类型。例如：燃烧煤、石油、天然气等化学能的火力发电厂；利用水的动能发电的水力发电厂；利用核能发电的核动力发电厂。本文探究了传统的火力、水力、核能发电方式及一些新能源发电方式。

关键词：发电；火力发电；水力发电；核能发电；新能源。 1、

火力发电

火力发电的主要发电设备包括锅炉、汽轮机和发电机，其辅助设备有冷凝器、给水加热器、各种水泵、磨煤机、除氧器、烟囱及各种量测与控制设备。原煤从煤矿运到电厂后，先存入原煤仓，随后由输煤皮带运进原煤斗，从原煤斗落入球磨机中被磨成很细的煤粉，再由排粉机抽出，随同热空气送入锅炉的燃烧室进行燃烧。

燃烧放出的热量一部分被燃烧室四周的水冷壁吸收，一部分加热燃烧室顶部和烟道入口处的过热器中的蒸汽，余下的热量则被烟气携带穿过省煤器、空气预热器传递给这两个设备内的水和空气。烟气经过除尘器净化处理，由吸风机导入烟囱，被排入大气。燃烧时生成的灰渣和由除尘器收集下来的细灰，用水冲进冲灰沟排出厂外。

燃烧用的助燃空气，经送风机进入空气预热器中加热，加热后，一部分被送往磨煤机作为干燥和运送煤粉的介质，大部分送入燃烧室参与助燃。水、蒸汽是把热能转化成机械能的重要介质。净化后的给水，先送进省煤器预热，继而进入汽包，由汽包降入水冷壁管中吸收燃烧室的热能后蒸发成蒸汽。蒸汽通过过热器时，再次被加热，变为高温高压的过热蒸汽。过热蒸汽经主蒸汽管道进入汽轮机膨胀做功，推动汽轮机转子转动，将热能转变为机械能。做完功的蒸汽在凝结器中被冷却凝结成水。凝结水经除氧器去氧、加热器加热后再用给水泵重新送入省煤器预热，便可作为工质继续循环使用。凝结器需要的冷却水由循环水泵送入，冷却水在凝结器中吸热之后，流回冷却塔散热，然后，再经循环水泵供给凝结器。汽轮机转子转动带动发电机转子旋转，在发电机中又把机械能转换成电能。发电机发出的电能经过变压器升高电压后送入高压电力网。

2、水力发电

水力发电是利用河流所蕴藏的水力能资源来发电，水力能资源是最干净、价廉的能源。水力发电厂的容量大小决定于上下游的水位差(简称水头)和流量的大小。因此，水力发电厂往往需要修建拦河大坝等水工建筑物以形成集中的较高水位差，并依靠大坝形成具有一定容积的水库，以调节河水流量。根据地形、地质、水能资源特点等的不同，水力发电厂的形式是多种多样的。

水力发电的生产过程要比火力发电简单。由拦河坝维持在高水位的水，经压力水管进入螺旋形蜗壳，推动水轮机转子旋转，将水能变为机械能。水轮机转子

再带动发电机转子旋转，使机械能变成了电能。而做完功的水则经过尾水管排往下游。发电机发出的电，经变压器升压后由高压输电线送至用户。水利发电厂的优势：首先，水利发电厂的生产过程较简单，故所需的运行维护人员较少，且易于实现全盘自动化。其次，水力发电厂不消耗燃料，故电能成本要比火力发电厂低得多。此外，水力机组的效率较高，承受变动负载的性能较好，故在系统中的运行方式较为灵活。水力机组启动迅速，在事故时能有力地发挥其后备作用。再者，随着水力发电厂的兴建往往还可以同时解决发电、防洪、灌溉、航运等多方面的问题，从而实现河流的综合利用，使国民经济取得更大效益。水力发电厂的另一个优点是不像火力发电厂、核能发电厂那样存在环境污染问题。水利发电厂的劣势：由于水力发电厂需要建设大量的水工建筑物，所以相对于火电厂来说，建设投资大，工期较长，使用劳力也较多。特别是水库还将淹没一部分土地，给农业生产带来一定不利影响。水力发电厂的运行方式还受到气象、水文等条件的影响，有丰水期、枯水期之别，发电出力不如火电厂稳定，也给电力系统的运行带来一定不利因素。

3、核能发电厂

核能是一种新的能源，也是可望长期使用的能源。所以，自19年世界上第一座核电厂投入运行以来，许多国家纷纷建设核电厂。核电厂建设的速度最快 。

核能发电的基本原理：核燃料在反应堆内产生核裂变，即所谓链式反应，释放出大量热能，由冷却剂(水或气体)带出，在蒸汽发生器中将水加热为蒸汽。然后，同一般火力发电厂一样，用蒸汽推动汽轮机，再带动发电机发电。冷却剂在把热量传给水后，又被泵打回反应堆里去吸热，这样反复使用，就可以不断地把核裂变释放的热能引导出来。核能发电厂与火力发电厂在构成上最主要区别是前者用核一蒸汽发电系统来代替后者的蒸汽锅炉，所以核电厂中的反应堆又被称为原子锅炉 。核能发电厂的特点和问题：核能发电厂的主要优点之一是可以大量节省煤、石油等燃料。核能发电厂的另一个特点是燃烧时不需要空气助燃，所以核能电厂可以建设在地下、山洞里、水下或空气稀薄的高原地区。核能发电厂的主要问题是放射性污染。但随着科学技术的发展，将会变得越来越安全 。目前大多数商业运行的核电厂属于水堆型，包括压水堆、沸水堆和重水堆。正在研究开发中的有快中子增殖堆和高温气冷堆核电厂。

4、新能源发电

新能源发电主要有风能发电、太阳能发电、地热能发电、潮汐能发电等 风力发电：风力发电是通过风力发电机组将风能转化成机械能，再转化为电能 。风力发电的原理，是利用风力带动风车叶片旋转，再透过增速机将旋转的速度提升，来促使发电机发电。依据目前的风车技术，大约是每秒三米的微风速度，便可以开始发电。 风力发电正在世界上形成一股热潮，因为风力发电不需要使用燃料，也不会产生辐射或空气污染。

太阳能发电：太阳能发电方式主要利用太阳能电池来产生电能，太阳能电池是一对光有响应并能将光能转换成电力的器件。当光线照射太阳能电池表面时，一部分光子被硅材料吸收；光子的能量传递给了硅原子，使电子发生了越迁，成为自由电子在P－N结两侧集聚形成了电位差，当外部接通电路时，在该电压的

作用下，将会有电流流过外部电路产生一定的输出功率。这个过程的实质是：光子能量转换成电能的过程。

地热能发电：通过热流体将地下热能携带到地上，经过专门的装置将地下热能转换为机械能，然后再把机械能转换为电能的生产过程。根据地热能的赋存形式，地热能可分为蒸汽型、热水型、干热岩型、地压型和岩浆型等五类。从地热能的开发和能量转换的角度来说，上述五类地热资源都可以用来发电，但日前开发利用得较多的是蒸汽型及热水型两类资源。地热发电的有点是：一般不需燃料，发电成本上多数情况下都比水电、火电、核电要低，设备的利用时间长，建厂投资一般都低于水电站，且不受降雨拉季节变化的影响，发电稳定，可以人人减少环境响污染等等。

潮汐发电：潮汐发电与普通水利发电原理类似，通过出水库，在涨潮时将海水储存在水库内，以势能的形式保存，然后，在落潮时放出海水，利用高、低潮位之间的落差，推动水轮机旋转，带动发电机发电。

此外还有生物能、波浪能、海洋温差能等。从远景发展来看，还有聚变能、氢能等 。各种发电方式都有各自的优缺点，具体采用哪种方式应该根据实际情况择优选择。比如说，国北方煤炭资源丰富，这些地方多采用火力发电；我国西北地区常年有大风且风力稳定，这些地方多采用风力发电；我国黄河、长江等大河附近水流量大，水流落差高，这些地方多采用水力发电。

Analysis of power generation

Abstract: Power generation is the core of energy production, responsible for the different types of primary energy into electrical energy task. Based on the use of different energy sources, power plants can be divided into many types. For example: the burning of coal, oil, gas and other chemical energy of the thermal power plant; use the kinetic energy of water power hydro power plants; the use of nuclear power nuclear power plants. This article explores the traditional fire, water, nuclear power generation and new energy power generation.

Keywords: power generation; thermal power; hydropower; nuclear power; new energy.

1, thermal

The main thermal power generation equipment including boilers, turbines and generators, the auxiliary equipment condensers, feedwater heaters, all kinds of pumps, mill, deaerator, chimneys, and a variety of measurement and control equipment. Transported to the power plant from coal mine, the first into the coal storage, then transported by a coal conveyer belt into the coal bucket, coal bucket from falling into the ball mill was ground into very fine coal, then row out of powder, along with heat air into the boiler combustion chamber for combustion.

Part of the heat released by the combustion chamber around the water wall absorption, the top part of the heating chamber and flue entrance of the steam superheater, heat the remaining gas was carried through the economizer, air preheater passed to the two devices in the water and air. Flue gas through the filter purification, by the suction fan into the chimney, entering the atmosphere. Combustion-generated ash and dust collection down by the thin gray, water rushed into the ash discharge ditch outside the factory.

Burning with the combustion air, the blower into the air preheater heating, heating, some were sent to transport coal mill as dry and the media, most of the combustion into the combustion chamber to participate. Water, steam is the heat energy into mechanical energy of the important media. Purified water, first sent to the economizer warm, and then into the drum, the drum down into the combustion chamber wall tube to absorb the heat evaporates into the steam. Steam through the superheater, the re-heated, high temperature and pressure into the superheated steam. Superheated steam into the turbine by expansion of the main steam pipe acting to promote the turbine rotor, the heat energy into mechanical energy. Done successfully in the steam is cooled in the condenser condenses into water. Phenylephrine by deaerator condensate, heater and then re-fed with economizer to preheat water pump can be used as a refrigerant cycle to continue. Condenser cooling water required by the circulating pump into the cooling water absorbs heat in the condenser, the heat back into the cooling tower, and then, via the supply condenser circulating water pump. Turbine rotor to drive the generator rotor rotation, the generators convert mechanical energy into electrical energy again. Generator of electricity through the

issue of increased voltage transformer into the power grid.

2, hydropower

Hydropower is the use of river water to a reservoir of resources to generate electricity, hydro resources are the most clean, inexpensive energy. Hydroelectric power plant capacity depends on the size difference between the upstream and downstream water level (the head) and the size of the flow. Therefore, often requires the construction of hydroelectric power plant dams and other hydraulic structures weir to form a higher concentration of water is poor, and rely on the formation of a certain volume of the dam reservoir to regulate water flow. Based on topography, geology, water resources, characteristics of different forms of hydropower plants are diverse.

Hydroelectric power production process than the simple thermal power. From the dam to maintain a high level of water through the pipes into the spiral volute pressure to promote the turbine rotor, the water into mechanical energy. Turbine driven generator rotor then the rotor rotation, so that mechanical energy into electrical energy. The power of water is done through the tail pipe discharged into the downstream. The electricity generator, the transformer voltage to high voltage transmission lines sent by the user. Hydroelectric power plant advantages: First, the hydroelectric power plant's production process is relatively simple, it required less operation and maintenance personnel, and easy to implement comprehensive automation. Second, the hydroelectric power plant does not consume fuel, so electricity costs are much lower than the thermal power plant. In addition, the hydraulic unit more efficient, better performance under load changes, so the operation mode in the system more flexible. Hydro unit start quickly, when the accident back to play its role effectively. Moreover, with the construction of hydroelectric power plants often can simultaneously address power generation, flood control, irrigation, navigation, and many other issues, in order to achieve the comprehensive utilization of the river, the national economy to achieve greater efficiency. Another advantage of hydroelectric power plant is unlike thermal power plants, nuclear power plants, as there is environmental pollution. Hydroelectric power plant disadvantages: the need to build large hydroelectric power plant because of hydraulic structures, so relative to the thermal power plant, the construction of large investment and a longer duration, use of labor is greater. Particular part of the reservoir will flood the land, to bring some negative impact of agricultural production. Hydroelectric power plant operation mode is also affected by meteorological, hydrological and other conditions, there is the wet period, dry season of the other, stable power output than power plants, but also to bring some electricity to run the system disadvantages.

3, nuclear power plants

Nuclear energy is a new energy, but also the expected long-term use of energy. So, since 19 the world's first nuclear power plant put into operation, many countries have nuclear power plant construction. Nuclear power plant construction the fastest.

The basic principle of nuclear power: nuclear fuel to generate nuclear fission in the reactor, the so-called chain reaction, releasing large amounts of heat from the coolant (water or gases) out, the water will be heated in the steam generator to steam. Then, as with the general thermal power plants with steam turbine drive, then drive generators. Coolant in the heat to the water after he was pumped to go back to the endothermic reactor, so that repeated use can keep the heat released by nuclear fission to guide them. Nuclear power plants and thermal power plants constitute the main difference is that the former on a steam with nuclear power generation system to replace the latter's steam boiler, so the reactor nuclear power plant is also known as atomic boiler. Nuclear power plant characteristics and problems: The main advantages of nuclear power plant can save a lot of coal, oil and other fuels. Another feature is a nuclear power plant does not require combustion air for combustion, it can build nuclear power plants in the ground, cave, underwater, or the thin air of the highlands. The main problem is that nuclear power plant radioactive contamination. But with the development of science and technology, will become more and more security. Most commercial operation of nuclear power plants are water reactor type, including pressurized water reactors, boiling water reactor and heavy water reactors. There is research and development in the fast breeder reactor and HTR nuclear power plants.

4, new energy power generation

New energy generation are wind, solar power, geothermal power, tidal power, etc.

Wind power: Wind power by wind turbine wind energy into mechanical energy and then into electricity. The principle of wind power, wind power is driving the use of windmill blades rotating, and then through the growth machine will improve the speed of rotation, to encourage generators. According to the current windmill technology, is about three meters per second speed of the breeze, they can start generating electricity. Wind power is the formation of a craze in the world, because wind power without using fuel, it does not produce radiation or air pollution. Solar power: Solar power generation mainly to produce electricity using solar cells, solar cells is a response to light and can convert light energy into electrical devices. When light solar surface, part of the photons absorbed by silicon material; photon energy transfer to the silicon atom, the electron transfer occurred in Vietnam, becoming free electrons in the P-N junction on both sides gathered to form a potential difference, when the external access through the circuit, the voltage effect, there will be current flow through an external circuit to generate a certain output power. The essence of this process: the photon energy into electrical energy in the process. Geothermal power generation: thermal fluid through the heat carried to the ground floor, through a special device will be underground heat into mechanical energy, mechanical energy and then converted to electrical energy production process. Occurrence form of base heat, geothermal energy can be divided into the steam-based, water based, hot dry rock type, ground pressure, such as five-and magma-type. From geothermal energy development and energy conversion point of view, the above five

categories of geothermal resources for power generation, but have more recently developed is the use of steam and hot water type two types of resources. Geothermal power is a kind of: general need of fuel, electricity costs in most cases than the hydropower, thermal power, nuclear power is lower, the equipment used for a long time, investments are generally lower than the hydroelectric plant, and is not pulling the seasonal variation of rainfall influence, power and stability, can all reduce the environmental impact pollution, and so on.

Tidal power: tidal power and hydroelectric power works like an ordinary, through the reservoir, at high tide when the water stored in reservoirs, in the form of potential energy saving, and then release water at low tide, using high, the gap between low tide level, promote the turbine rotation, driven generators.

There are also bio-energy, wave energy, ocean thermal energy, etc. From the long-term development perspective, there are fusion energy, hydrogen energy and so on. Various power generation has its own advantages and disadvantages, the specific manner in which the actual situation should be based on merit selection. For example, north of the country rich in coal resources, where to use more thermal power; Northwest China and the wind steady winds year round, these places use more wind power; China's Yellow River, Yangtze and other rivers near the water volume, high-flow gap, where more use of hydroelectric power.