Scott Still Machine
The Scott still machine or still machine is a heat engine that works as a diesel engine and a steam engine at the same time .
history
The machine was patented in 1913 by William Joseph Still. The patent was published in 1917 and the machine was first presented to the public in 1919. The first use took place in 1924 by the Scotts Shipbuilding and Engineering Company in the construction of the cargo ship Dolius of the Blue Funnel Line , which was equipped with two double-acting four-cylinder engines, each with an output of 1250 hp. In 1928 the same shipping company had the Eurybates built with two Scott Still machines, each with an output of 2500 hp, with separate diesel and steam pistons. This was converted to pure diesel operation in 1948. In the 1920s and 1930s there were also attempts to use Scott-Still machines to drive locomotives. Despite the clearly measurable under-consumption, the more demanding operation and progress in conventional diesel engine construction led to the discontinuation of the construction of further machines of the Still type.
principle
The original working principle was that of a double-acting piston engine , the top of the piston being operated as an internal combustion engine based on the principle of a two-stroke diesel engine and the bottom of the piston being operated as a steam engine. The thermal energy of the exhaust gas side and the engine cooling was used, or also used, to generate the steam required for operation.
Since the exhaust gases from the two-stroke engine are fed into the boiler's combustion chamber, the (residual) fuel contained in the exhaust gas is used to heat the boiler.
advantages
Machines based on the Still principle had low fuel consumption compared to the diesel engines available at the beginning of the 1920s, which, however, went hand in hand with increased construction and maintenance costs and required double-qualified machine personnel. Further advantages were the possibility of using the steam engine alone or increasing the output by generating additional steam in the steam boiler.
Later Scott-Still machines worked with separate diesel and steam pistons to avoid cross-contamination of oil and steam.
Individual evidence
literature
- Heinrich Dubbel: Oil and gas machines (stationary and ship machines) , J. Springer, Berlin, 1926
- Myron Seiliger : The high-performance diesel engines , J. Springer, Berlin, 1926
- Friedrich Sass: Compressorless diesel machines (pressure injection machines) , J. Springer, Berlin, 1929
