核燃料在反应堆内发生裂变而产生大量热能,再被高压水把热能带出,在蒸汽发生器内产生蒸汽,蒸汽推动汽轮机带动发电机发电。 一回路反应堆堆芯因核燃料裂变产生巨大的热能,由主泵泵入堆芯的水被加热成327度、155个大气压的高温高压水,高温高压水流经蒸汽发生器内的传热U型管,通过管壁将热能传递给U型管外的二回路冷却水,释放热量后又被主泵送回堆芯重新加热再进入蒸汽发生器。水这样不断地在密闭的回路内循环,被称为一回路。 二回路蒸汽发生器U型管外的二回路水受热从而变成蒸汽,推动汽轮发电机做功,把热能转化为电力:做完功后的蒸汽进入冷凝器冷却,凝结成水返回蒸汽发生器,重新加热成蒸汽。这样的汽水循环过程,被称为二回路。 三回路三回路使用海水或淡水,它的作用是在冷凝器中冷却二回路的蒸汽使之变回冷凝水。 什么是核燃料? 核燃料是可在核反应堆中通过核裂变产生核能的材料,是铀矿石经过开采、初加工、铀转化、铀浓缩,进而加工成核燃料元件。 压水堆核电站用的是浓度为3%左右的核燃料(铀一235)。大亚湾核电站的核反应堆内有157个核燃料组件,每个组件由17×17根燃料棒组成。燃料棒由烧结二氧化铀芯块装入锆合金管中封焊构成。一个燃料组件中有一束控制棒,控制核裂变反应。 利用核能生产电能的电厂称为核电厂。由于核反应堆的类型不同,核电厂的系统和设备也不同。压水堆核电厂主要由压水反应堆、反应堆冷却剂系统(简称一回路)、蒸汽和动力转换系统(又称二回路)、循环水系统、发电机和输配电系统及其辅助系统组成,其流程原理如图2.1所示。通常将一回路及核岛辅助系统、专设安全设施和厂房称为核岛。二回路及其辅助系统和厂房与常规火电厂系统和设备相似,称为常规岛。电厂的其他部分,统称配套设施。实质上,从生产的角度讲,核岛利用核能生产蒸汽,常规岛用蒸汽生产电能。 反应堆冷却剂系统将堆芯核裂变放出的热能带出反应堆并传递给二回路系统以产生蒸汽。通常把反应堆、反应堆冷却剂系统及其辅助系统合称为核供汽系统。现代商用压水堆核电厂反应堆冷却剂系统一般有二至四条并联在反应堆压力容器上的封闭环路(见图2.2)。每一条环路由一台蒸汽发生器、一台或两台反应堆冷却剂泵及相应的管通组成。一回路内的高温高压含硼水,由反应堆冷却剂泵输送,流经反应堆堆芯,吸收了堆芯核裂变放出的热能,再流进蒸汽发生器,通过蒸汽发生器传热管壁,将热能传给二回路蒸汽发生器给水,然后再被反应堆冷却剂泵送入反应堆。如此循环往复,构成封闭回路。整个一回路系统设有一台稳压器,一回路系统的压力靠稳压器调节,保持稳定。 为了保证反应堆和反应堆冷却剂系统的安全运行,核电厂还设置了专设安全设施和一系列辅助系统。 一回路辅助系统主要用来保证反应堆和一回路系统的正常运行。压水堆核电厂一回路辅助系统按其功能划分,有保证正常运行的系统和废物处理系统,部分系统同时作为专设安全设施系统的支持系统。专设安全设施为一些重大的事故提供必要的应急冷却措施,并防止放射性物质的扩散。 二回路系统由汽轮机发电机组、冷凝器、凝结水泵、给水加热器、除氧器、给水泵、蒸汽发生器、汽水分离再热器等设备组成。蒸汽发生器的给水在蒸汽发生器吸收热量变成高压蒸汽,然后驱动汽轮发电机组发电,作功后的乏汽在冷凝器内冷凝成水,凝结水由凝结水泵输送,经低压加热器进入除氧器,除氧水由给水泵送入高压加热器加热后重新返回蒸汽发生器,如此形成热力循环。为了保证二回路系统的正常运行,二回路系统也设有一系列辅助系统。 循环水系统主要用来为冷凝器提供冷却水。 我们看到,在压水堆电厂,一回路系统的冷却剂与汽轮机回路工质是完全隔离的,这就是所谓的间接循环。采用间接循环具有使二回路系统免受放射性玷污的优点,但它与采用直接循环的沸水堆核电厂(图2.3)相比,增加了蒸汽发生器。压水堆体积较小和控制要求简单等因素可以弥补这一不足,并使这种系统设计在经济上具有竞争力。 发电机和输配电系统的主要设备有发电机、励磁机、主变压器、厂用变压器、启动变压器、高压开关站和柴油发电机组等组成。其主要作用是将核电厂发出的电能向电网输送,同时保证核电厂内部设备的可靠供电。 发电机的出线电压一般为22kV左右,经变压器升至外网电压。为保证核电厂安全运行,核电厂至少与两条不同方向的独立电源相连接,以避免因雷击、地震、飓风或洪水等自然灾害可能造成的全厂断电。 每台发电机组的引出母线上,均接有两台厂用变压器。为厂用电设备提供高压电源。高压厂用电系统一般为6kV左右。该高压厂用电系统直接向核电厂大功率动力设备供电。对于小功率设备,经 变压器降压后供给380220V低压电源。通常高压厂用电系统分为工作母线和安全母线两部分,高压厂用电系统的工作母线,可以由外电网或发电机供电,高压厂用电的安全母线,除外网和发电机外,还可由柴油发电机供电。 在电厂正常功率运行时,发电机发出的电能大部分经主变压器升压至外网电压输送给用户。同时,整个厂用设备的配电系统由发电机的引出母线经厂用变压器降压后供电。当发电机停机时,则由外部电网经启动变压器供电。当外网和发电机组都不能供电时,则由柴油发电机组向安全母线供电,以保证核电厂设备的安全。点击图片可放大 输配电系统的设计与机组容量、电网系统环境等密切相关,各核电厂设计会有较大差异。vartagarray="["cdma无线视频服务器","采购","设备","施工","工程","建筑弱电","系统","设计","预审","变压器","电气","机组","电力","空调","辅机","安防","招标","电厂","PLC","内蒙古","节能","设计师","应用","电梯","变电站","发电","电子警察","发电厂","大唐","风电场","电缆","变频器","电力系统","煤矿","水电站","监控系统","云南","电网","招聘","国电","单片机","技术","物资","项目","建筑","上海","污水处理","热电厂","热电","锅炉","控制","高速公路","通风管道","工程施工","控制系统","方案","标段","装置","消防","土建","神华","水库","山西","中央空调","LED","能源","网络","给排水","风电","照明","改造","软件","节能环保","公路","自动化","电站","线路","现场总线","故障","水泥","监控","华电","责任","天津","仿真","防雷","建造师","电源","宁夏","结构","图纸","断路器","贵州","华能","铁路","太阳能","水泵","供电局","智能建筑","污水处理厂"]";vartagencarray="["cdma%CE%DE%CF%DF%CA%D3%C6%B5%B7%FE%CE%F1%C6%F7","%B2%C9%B9%BA","%C9%E8%B1%B8","%CA%A9%B9%A4","%B9%A4%B3%CC","%BD%A8%D6%FE%C8%F5%B5%E7","%CF%B5%CD%B3","%C9%E8%BC%C6","%D4%A4%C9%F3","%B1%E4%D1%B9%C6%F7","%B5%E7%C6%F8","%BB%FA%D7%E9","%B5%E7%C1%A6","%BF%D5%B5%F7","%B8%A8%BB%FA","%B0%B2%B7%C0","%D5%D0%B1%EA","%B5%E7%B3%A7","PLC","%C4%DA%C3%C9%B9%C5","%BD%DA%C4%DC","%C9%E8%BC%C6%CA%A6","%D3%A6%D3%C3","%B5%E7%CC%DD","%B1%E4%B5%E7%D5%BE","%B7%A2%B5%E7","%B5%E7%D7%D3%BE%AF%B2%EC","%B7%A2%B5%E7%B3%A7","%B4%F3%CC%C6","%B7%E7%B5%E7%B3%A1","%B5%E7%C0%C2","%B1%E4%C6%B5%C6%F7","%B5%E7%C1%A6%CF%B5%CD%B3","%C3%BA%BF%F3","%CB%AE%B5%E7%D5%BE","%BC%E0%BF%D8%CF%B5%CD%B3","%D4%C6%C4%CF","%B5%E7%CD%F8","%D5%D0%C6%B8","%B9%FA%B5%E7","%B5%A5%C6%AC%BB%FA","%BC%BC%CA%F5","%CE%EF%D7%CA","%CF%EE%C4%BF","%BD%A8%D6%FE","%C9%CF%BA%A3","%CE%DB%CB%AE%B4%A6%C0%ED","%C8%C8%B5%E7%B3%A7","%C8%C8%B5%E7","%B9%F8%C2%AF","%BF%D8%D6%C6","%B8%DF%CB%D9%B9%AB%C2%B7","%CD%A8%B7%E7%B9%DC%B5%C0","%B9%A4%B3%CC%CA%A9%B9%A4","%BF%D8%D6%C6%CF%B5%CD%B3","%B7%BD%B0%B8","%B1%EA%B6%CE","%D7%B0%D6%C3","%CF%FB%B7%C0","%CD%C1%BD%A8","%C9%F1%BB%AA","%CB%AE%BF%E2","%C9%BD%CE%F7","%D6%D0%D1%EB%BF%D5%B5%F7","LED","%C4%DC%D4%B4","%CD%F8%C2%E7","%B8%F8%C5%C5%CB%AE","%B7%E7%B5%E7","%D5%D5%C3%F7","%B8%C4%D4%EC","%C8%ED%BC%FE","%BD%DA%C4%DC%BB%B7%B1%A3","%B9%AB%C2%B7","%D7%D4%B6%AF%BB%AF","%B5%E7%D5%BE","%CF%DF%C2%B7","%CF%D6%B3%A1%D7%DC%CF%DF","%B9%CA%D5%CF","%CB%AE%C4%E0","%BC%E0%BF%D8","%BB%AA%B5%E7","%D4%F0%C8%CE","%CC%EC%BD%F2","%B7%C2%D5%E6","%B7%C0%C0%D7","%BD%A8%D4%EC%CA%A6","%B5%E7%D4%B4","%C4%FE%CF%C4","%BD%E1%B9%B9","%CD%BC%D6%BD","%B6%CF%C2%B7%C6%F7","%B9%F3%D6%DD","%BB%AA%C4%DC","%CC%FA%C2%B7","%CC%AB%D1%F4%C4%DC","%CB%AE%B1%C3","%B9%A9%B5%E7%BE%D6","%D6%C7%C4%DC%BD%A8%D6%FE","%CE%DB%CB%AE%B4%A6%C0%ED%B3%A7"]";
信息发布:广州名易软件有限公司 http://www.myidp.net
|