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The steam engine

Topic: Inventions
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Technical Description

Using the steam heat energy is converted to kinetic energy. Water is boiled in a boiler, so that it becomes steam under pressure. In a cylinder affects the vapor pressure of the piston, which in turn conveys the mechanical work. The first steam engines were used to pump water out of mines, which had previously used horse-drawn pumps. Therefore counted steam engine in the power in horsepower, then you knew how many (tired and bored) horses they would replace. The pumps could be used a reciprocating movement directly. Otherwise it has a connecting rod that transfers power to a rotating shaft.

The piston may be single acting or double acting. A valve mechanism to control the vapor pressure alternately to one or the other side of the piston of a double-acting steam cylinder. Thus develops force in both directions. If the machine has two cylinders, which works with a quarter-turn shift, so it can start itself as always at least one cylinder is in the working phase. For example, on a steam train would not it be so convenient if you had to push in time there! Two double-acting steam cylinders correspond in this regard a four-cylinder two-stroke internal combustion engine, or an eight-cylinder four-stroke engine.

The steam generated in a boiler, which in principle can be fired with anything. Traditionally, coal, of which there were plenty of in England, and that includes a lot of energy.

In a power plant or larger ships can use a steam turbine instead of a piston steam engine, but the principle is the same. The efficiency of heat into mechanical energy (and on to electrical energy) is not so high, about 30 - 40%. The heat source may be oil, coal, biomass or nuclear energy.


The use of steam engines was one of the foundations for the Industrial Revolution. It was no longer as dependent on hydropower for mining pumps and machinery. That enabled efficient transport with ships and railways. In combination with the new machines, especially in English textile industry arose manufacturing industries that could be run on a large scale.

The largest use of steam engines were in the 1800s, before combustion engines and electric energy gained greater importance. But in a way going on the steam revolution still. The use of fossil fuels has increased dramatically, and threaten the Earth's climate. In China opens a new major coal power plant every month.


Steam technology still gives us great opportunities, if it can be used properly. One can, as in Vasteras, use bio-fuel, and with CHP Utilise this to both electricity and heat at the same time. In this case the total efficiency more than double. But unfortunately it is not enough. Man fires also here with coal, and cools the heat surplus in Mälaren to produce more electricity. The demand for electrical energy is so large that it starts new power plants, sometimes based on natural gas or coal.
steam engine, the piston machine with one or more pistons moving reciprocally and converts the energy of water vapor of more or less high pressure into mechanical work. Even so-called rotary steam engines with klafförsedda rotors appeared (James Watt in 1781, the brothers Alrik and Oscar Hult 1895). The origin is Watts improvement of Newcomen atmospheric steam engine with the introduction of the separate condenser (1769). Watts single acting machine (which only one piston side is exposed to the vapor pressure) developed in 1782 to a double acting machine in which valves (later a slide constructed by William Murdock 1799) supply steam alternately in one or the other piston side. In the expansion machine (Watt 1782) takes the steam supply only for about half the battle (ie piston displacement between the turning points). During the remainder of the battle expands steam with continued energy conversion.

Growth in effect would the single-cylinder machines have led to a grotesque size of the cylinder. For this and several other reasons developed multi-cylinder machines in which steam is either distributed in two equal cylinders (twin engine) or at two in the series by pouring cylinders, where the expansion begins in a high-pressure cylinder and finished in a low-pressure cylinder (kompoundmaskin, Jonathan Hornblower, 1781). Kompoundmaskinen has developed into triple and kvadrupelexpansionsmaskiner.

Drain steam is either out in the open (in the so-called friblåsare, even abusively called high-pressure machines) or to a condenser where the vapor is getting water (condensation machinery). The pressure in the condenser corresponds to the cooling water temperature and becomes about 0.05 bar (5 kPa), resulting in better utilization of steam energy content, but about 2/3 of the input energy is lost anyway with the cooling water. The low pressure involves a large volume flow of steam in the outlet, which limits the power of the engines to 12 000 kW. Friblåsarna received early general use in ånglokomotiven, while condensing machines dominated among desktop machines and sjöångmaskiner.

Two basic types of steam engines can be distinguished: horizontal machines (with horizontal cylinders) and vertical machines. While other designs have appeared, such as the machines with oscillating cylinders that existed in the marine area. The steam engine was fully developed around 1910, before the diesel engine and the steam turbine finished evolved. The best steam engine the efficiency was then at about 25%. By steam data (pressure and temperature) subsequently escalated and the steam engine supplemented with sewage turbine efficiency has been increased to about 30%. For outputs of 12 000 kW, assumes the diesel engine and the steam turbine over, because they lack kolvångmaskinens limitations. At very large effects (in the range of 40 MW - 1000 MW) steam turbine is supreme.


The first industrially useful steam engine was built by the English wrought champion Thomas Newcomen in 1712. This so-called atmospheric steam engine had a vertical, at its upper end open cylinder. Piston top side was therefore under constant influence of the ambient air pressure (atmospheric pressure). The existing space below the piston alternately filled with steam (wherein the piston via the balance beam is lifted up by the weight of the pump rods in the second end of the boom) and cooled by injecting cold water, whereby the steam was condensed and vacuum occurred in the cylinder. The atmospheric pressure then pinned down on the plunger again. Such machines were used for pumping out the English coal mines. They had an efficiency of about 0.4% and spent large amounts of carbon. The first steam engine in Sweden was a Newcomen machine that Marten Triewald built at the Dannemora mine in 1728.

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