System Doble
A to System Doble designated boiler is a design of the once-through - steam boiler to produce steam for the operation of steam railcar modern construction and other steam-powered vehicles for smaller power to 100 hp. It got its name from the Doble company in Emeryville , USA .
description
Vehicles with prime movers from the Doble company had already been used on some trucks in the USA . Compared to conventional systems, vehicles based on the Doble system differed in a system of condensation of the exhaust steam in a circuit. Although the circulating work processes were controlled by a closed-loop control system, the operation was as simple as conventional control of a steam locomotive . The processes of the individual control devices happened automatically through the position of the regulator as well as the control, the steam pressure and the speed of the steam engine. The system is characterized by its relatively small dimensions.
The system of the steam locomotive boiler was designed for an operating pressure of 100 bar. The steam generator is formed from a single coil into which the feed water is pressed from below by a feed pump operated with live steam via a preheater. The control of the fuel, mostly consisting of lignite tar oil, and the combustion air happened automatically. The combustion air was forced into the combustion chamber by a fan driven by an exhaust steam turbine. The fuel supply was done electromechanically depending on the steam temperature and the steam pressure. The exhaust steam, after being expanded in the steam engine, after being passed through a preheater for the feed water, was pressed into a cooler and precipitated as condensate by cooling in a collecting tank. The cooling was provided by a turbine with a fan wheel driven by the exhaust steam. This significantly minimized the excessive risk of scale formation from fresh water. The steam engine was fast-running and produced greater performance with smaller dimensions.
In practice, vehicles equipped with the Doble system did not achieve the required performance. They did not react quickly enough to sudden load changes. Different steam temperatures and steam pressures were found, so that the valve box pressure required for a specific load case was not always achieved. In the long-term test, numerous failures resulted from the destruction of pipes that were exposed to the greatest thermal loads. A decisive factor was the use of the fuel, the quality of which steam engines were sometimes sensitive to. The vehicles were therefore more unreliable than those with a diesel engine drive of the same performance class.
Steam railcars equipped with the Doble system in Germany
| vehicle | Construction year | design type |
|---|---|---|
| DT 15-16 | 1932 | A1 h2v |
| LBE DT 2000 | 1933 | Bo'2 'h4v |
| DT 51-53 | 1934-1936 | Bo'2 'h4v |
| DT 54-58 | 1938 | Bo'2 'h4v |
| DT 59 | 1937 | Bo'2 'h4v |
literature
- Werner Willhaus: Kittel steam railcar . EK-Verlag, Freiburg 2008, ISBN 978-388255-106-8
- Rudolf Krebs: Five millennia of wheeled vehicles: 2 centuries of road traffic with thermal energy, over 100 years of automobiles . Springer-Verlag, Berlin, ISBN 978-3-642-93553-4 . ( limited preview in Google Book search)