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Spiral water-tube boilers are a family of vertical water-tube boilers. Their steam generating tubes are narrow spiral tubes, arranged in circular fashion around a central vertical water drum. The water tubes are long, numerous and of diameter, or smaller. This gives an extremely large heating area, and so good steam raising capabilities. "A maximum fire surface is obtained in a given space, and great economies in fuel are thereby made possible."〔 As both drum and tubes are of small diameter, the boilers are also suitable for high pressure use. However the boilers entered service early on, as one of the first small-tube water-tube designs and so they have rarely been used for high pressures or with steam turbines. Differences between these types of boiler are in the arrangement of their water tubes. They all share the same basic layout. The outer casing of the boiler is of steel plates, lined with firebrick, and plays no part in their heating area. == Climax boiler == The large industrial boiler known as the ''Climax'' was one of the first of this overall type. It was invented by Thomas F. Morrin and Walter W. Scott of New Jersey and was patented in 1884.〔 Steam Generator, Morrin & Scott, 1884〕〔 Steam Generator, Morrin & Scott, 1891〕〔 Steam Generator, Morrin, 1891〕 The water-tubes were single-turn loops aligned diagonally and arranged into horizontal tiers. The upper tube entry is vertically above the lower entry of the adjacent tube. In the original patent, tubes are hairpin-shaped with radial straight sections.〔 Later designs used a larger outer radius and "pear-shaped" tubes,〔 finally a tube shape that was almost the radius of the outer casing.〔 Reducing the curvature of tubes like this reduces the effects of expansion due to heating and the risk of leakage at the tube entries. The water level of these boilers was around 3/4 of the height of the tube tiers,〔 so that the upper tubes were filled with steam rather than water. Above the tube banks a single flat spiral tube was used as an economiser or feedwater heater.〔 The furnace used to fire these large boilers was annular, often with four or more separate firedoors. The boiler was also successfully fired with bagasse, plant waste or refuse. Where they were used for continual high-power production, such as for electricity generation, some were also used with early automatic stokers.〔 One advantage of these boilers was the rapidity with which they could be constructed. A factor in this was their pre-fabricated steel casings that were bolted together in sections.〔 Although their potential for high pressure was not made use of, they did gain a reputation for reliability and long service between overhaul.〔 These boilers were developed by Morrin & Scott at the "Clonbrook Steam-Boiler Works" and have no connection with either the Climax Locomotive Works or their logging locomotives. They were licensed for production to the "Clonbrook Steam-Boiler Co.", but in 1896, their previous manager Thomas J. Lawler began production of a competing boiler at the "Columbian Steam-Boiler Works" and Morrin & Scott successfully sued them for infringement of the Climax patents.〔(【引用サイトリンク】url=http://openjurist.org/90/f1d/285 )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Spiral watertube boiler」の詳細全文を読む スポンサード リンク
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