密西西比河西部次烟煤的蕴藏量约占美国煤藏量的25%,这些煤大多分布在远离人口集中的地区,过去未大规模开采。随着超高压输电技术的进展,能远距离送电,因此在次烟煤产区兴建了电厂;而且考虑到大气污染,这些低硫份煤正运销他处。燃烧工程公司(C.E.)十年来承制了一批次烟煤锅炉,容量为15至75万瓩。燃用次烟煤在经济性及可靠性方面对锅炉设计有一些特殊要求,因为要考虑到次烟煤热值低,水份高,有一定的灰特性。本文拟就次烟煤锅炉的设计和运行作些说明。次烟煤特性次烟煤具有适宜的特性,一般讲这些煤热值还是不太低的,应用基热值为4440至5560大卡/公斤、灰份5～15%、水份16～30%。表1列出了本文拟介绍的锅炉设计煤种的特性。次烟煤基本特性之一是水份较高,每百万大卡有18～72公斤以上的水份;灰份也很可观,每百万大卡有7～41.4公斤灰份。次烟煤水份高对锅炉设计的影响是多方面的,设计时要考虑到烟量及烟速的增加, The sub-bituminous coal reserves in the western Mississippi River account for about 25% of the U.S. coal reserves. Most of the coal is located far away from densely populated areas and has not been mined in the past. With the advancement of EHV transmission technologies, power can be delivered over long distances, so power plants are being built in sub-bituminous coal producing areas, and these low-sulfur coals are shipping elsewhere, given the air pollution. C.E. has contracted a batch of bituminous coal boilers over the past decade and has a capacity of 150,000 to 750,000 tonnes. Burning sub-bituminous coal has some special requirements on the design of the boiler in terms of economy and reliability because it takes into account that the sub-bituminous coal has low calorific value, high moisture content and certain ash characteristics. This article intends to sub-bituminous coal boiler design and operation of some instructions. Sub-bituminous coal has the characteristics of sub-optimal properties, generally speaking, these coal calorific value is not too low, the application of the base calorific value 4440 to 5560 kcal / kg, ash 5 to 15%, moisture 16 to 30%. Table 1 lists the characteristics of boiler design coal to be introduced in this paper. Sub-bituminous coal is one of the basic characteristics of high water per million kcal has 18 to more than 72 kg of water; ash is also very impressive, there are 7 to 41.4 kg ash per million kcal. The impact of sub-high bituminous coal moisture on the design of the boiler is manifold, and the design should take into account the increase in the amount of smoke and smoke,