The first half of eighteenth Century,the use of steam engines in the United Kingdom, including Watt's initial steamengine, including the steam pressure is equal to atmospheric pressure. In thelatter half of the eighteenth Century, the steam was replaced by a higher thanatmospheric pressure. Nineteenth Century, commonly used to increase the steampressure to about 0.8 mpa. And adapt the earliest steam boiler is a watercontaining large diameter cylindrical vertical boiler shell, then use ahorizontal boiler shell, a fire in the boiler shell bottom brick furnace body.
With bigger and bigger boiler, in orderto increase the heating area, in the boiler shell equipped with fireextinguishers, a fire in front of the fire extinguishers, the smoke came outfrom behind the fire extinguishers, through a brick flue row to the chimney andthe pot shell external heating, called the fire tube boiler. Started only afire extinguishers, known as single firebox boiler or Connie permits theboiler. Later added two fire extinguishers, said double firebox boiler or Lancashire boiler.
In 1830, after the production of highquality steel pipe and tube expanding technology, the fire tube boiler. Somefire tubes are arranged in the shell of the boiler, the main heating surface ofthe boiler is formed, and the fire (smoke) flows through the pipe. In thefollowing storage shell installed on the waterline as much as possible firetube, called horizontal tempering pipe external combustion boiler. Its metalconsumption is low, but it needs a lot of masonry.
In the middle of the nineteenthCentury, there was a water tube boiler. The heating surface of the boiler shellis outside the pipe, replaced the shell itself and the shell in fireextinguishers and fire tube. The increase of the heating area and the steampressure of the boiler is no longer limited by the shell diameter, which isbeneficial to increase the evaporation and steam pressure of the boiler. Thecylindrical shell of the boiler is changed to a drum, or a drum. In the early stage,the pressure and the capacity of the boiler are restricted by the straightpipe.
In the early twentieth Century, thesteam turbine began to develop, and it required a boiler with a high capacityand a high steam parameter. Straight pipe boiler（www.rguolu.com） has been unable to meet therequirements. With the development of manufacturing technology and watertreatment technology, a curved pipe type boiler has been developed. Starting isthe use of multi barrel type. With the application of water wall, superheaterand economizer, and drum internal steam, water separation element is improved,drum number decreased gradually, which not only saves the metal, and to improvethe boiler pressure, temperature, capacity and efficiency.