Serpollet cauldron
The Serpollet boiler is a steam generator with direct steam generation; This means that the boiler room only receives as much water as is immediately consumed in the connected steam engine. The usual water space in the boiler is avoided.
The boiler was invented and patented in 1881 by Henri Serpollet (1848–1915), and later it was significantly further developed by his brother Léon Serpollet .
The principle of steam generation used was not a new invention, it consists in injecting water between two externally heated metal walls that are as close as possible to each other, with instantaneous evaporation taking place. The Serpollet brothers used a copper pipe to manufacture the heating pipes, which was pressed together by hot rolling and then bent into a spiral. The feed device and steam line were connected to the two pipe ends and the water was fed into the pipe, which was heated to about 250 ° C. with petroleum .
The scale formation should be low with this type of construction. The feed device for fresh water had to work precisely; On the one hand, to prevent overheating and thus destruction of the pipelines and, on the other hand, so that the connected steam engine ran regularly. Later versions were also provided with transverse ribs in order to achieve a larger heating surface and greater resistance to internal pressure of up to 25 bar .
In France, these boilers were allowed to be installed without the otherwise prescribed safety devices. In addition to drives for small businesses, the boilers were also used to operate the Serpollet steam tricycle , steam railcars , bicycles and small steam ships.