热动专业英语第二章.ppt

为减少投资，大多数锅炉省煤器应用了各种鳍片以强化烟气侧的传热效率。鳍片是廉价的非承压物件，它可减少省煤器的总尺寸和造价。然而，成功的应用对于烟气环境是非常敏感的。表面的清洁能力是一关键因素。 Air heaters The air heater utilises the heat in the boiler flue gases leaving the economiser to heat the combustion air and provide hot air for drying coal. The air outlet temperature limit in coal fired plant is dictated by the coal mill exit temperature and capacity of the tempering air system with the gas outlet temperature limited by considerations of fouling of the heat transfer surface and corrosion of downstream equipment. 空气预热器 空气预热器是利用经过省煤器的锅炉烟气携带的热量加热燃烧空气，并提供干燥煤粉的热空气。在燃煤电厂中，空气预热器的出口温度受限于磨煤机的出口温度和调温风系统容量，烟气出口温度则要考虑传热表面的污染和后面设备的腐蚀情况。 On older boiler tubular or plate recuperators were generally used which were large, difficult to clean and did not lend themselves to easy replacement of damaged heating surface. On all modern boilers regenerators are used. 在较老的锅炉中一般采用管式或板式空预器，体积大，很难清理，而且坏损的传热表面不易替换。现代锅炉都采用回转式。 The most significant feature of regenerative air heaters, is the marked saving in space compared with recuperative designs. This stems from the adoption of a closely packed heating surface matrix, which is permissible only if good sootblowing facilities are available to keep it clean. 回转式空气预热器的最大特点是显著地节省了空间。回转式空预器采用紧密的受热面布置方式，必须采用性能良好的吹灰器使其保持清洁。 The heat transfer surface consists of steel or Corten plates pressed specific profile. The plates are 0.5mm to 0.8mm thick and are generally compressed and packed into solid steel containers which are then placed into the supporting structure. The profile of the plates is optimised to give high thermal performance with the minimum of pressure loss within the constraint of being adequately cleaned by sootblowing. 受热面由压制成特殊形状的钢板或考登钢板组成。这些板子厚0.5到0.8mm，一般被压紧并装进置于支撑结构上的钢制仓体。这些板子的形状经过优化，具有很高的传热效率，同时要在使用吹灰器充分保持清洁的情况下保证压损最小。 For a 660MW unit there are two airheaters, each 14.6m in diameter and weighing some 500 tonnes each. The surface area of the heat transfer su