The Simon Gas-Steam Engine

Gallery opened 4 Apr 2015

Updated: 11 Apr 2015

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The Simon engine was an attempt to make use of the large amount of waste heat produced by internal-combustion engines, by boiling water and using the steam in the same engine. The Still engine used the heat from a Diesel engine to create steam; the engine of Messrs Simon was fueled by gas. It was exhibited at Paris in 1878. Donkin says it was "Partly founded on Mr Beechey's design." but that statement remains obscure for the present.

The account given here is largely taken from A Text-book of Gas, Oil and Air Engines by Bryan Donkin, published by Charles Griffen & Co in 1900. The author has not been tracked down definitively, but he was probably the son of this Bryan Donkin (1809-1893) who in turn was the son of Bryan Donkin FRS. Our Donkin has dates of 1835-1902, and was the author of other books, including The Heat Efficiency of Steam Boilers and The Entropy Diagram and Its Applications. He also translated Theory and Construction of a Rational Heat Motor, by Rudolf Diesel, from the German. Otherwise he so far remains elusive. The Bryan Donkin Company still exists today.

Left: Simon engine with steam-boiler: 1878

The Simon engine, like other early gas engines, used separate cylinders for compression and for the power stroke. The cylinder on the left is the power cylinder and the smaller cylinder on the right the compression or pumping cylinder.

This engine has an underbeam, which reduces the height of the engine but increase its length. The operation is much the same as for the Henniges version below. The horizontal shaft A appears to be driven from the crankshaft by bevel gears, and apparently operates a valve between the pumping and power cylinders.

The exhaust gases pass through a coiled tube in the small boiler, and the heat from the water-jackets was also utilised. The water used to make steam was replaced by a small eccentic-driven pump.

A model of this engine (to what scale is unknown) was exhibited at the Universal Exposition of 1878 in Paris.

Left: Simon engine built by Otto Henniges & Co: 1880

This neater version of the Simon engine was buit by Otto Henniges & Co of Berlin-Moabit for some years though with little success. Despite all the complications of the steam drive the gas consumption was higher than Otto engines; one reason given was that the steam cooled the power cylinder too much. Henniges abandoned the technology.

Here A is the power cylinder and B the compression or pumping cylinder. Air and gas are drawn into B through slide-valve S1, are compressed, and then passed to power cylinder A via slide-valve S, which is driven from the crankshaft. j is a continually-burning gas jet on the A side of a wire gause which (so long as it remains intact) should prevent cylinder B exploding. This ignites the gas/air mixture and piston P is pushed down. The slide exhaust valve d is driven from the crankshaft and allows the hot exhaust gases to pass through coiled tubes e in the boiler F. When the water boils steam passes through pipe f and the top section of slide-valve S, to assist in pushing down the piston.

Given the size of the boiler, it is difficult to believe that it generated very much power, and there are all the extra complications of safety-valves, boiler feed pumps, pressure gauges, and so on.

On this point, according to Donkin, Professor Rudolf Schottler (who is unknown to Google) pertinently asks; "Whether it can be considered an advantage, since the gas engine is expressly designed to avoid the defects and dangers of a steam boiler, to add the latter to it?" One might add that in many countries there were strict regulations about employing qualified engineers to oversee steam engines, because of the risks of boiler explosion. This would have have been a major disincentive to using the Simon engine, and we can only conclude that he didn't think it through, did he?

Note that both the pumping and power cylinders have water jackets, the former presumably being needed because of the substantial amount of heat that is evolved when gases are compressed. I am only speculating, but presumably the jackets pre-heated the water fed to the boiler. (This is now confirmed for the 1878 version)

The Simon engine is unknown to Google, and this probably indicates a total lack of commercial success.

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