Advanced steam technology

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Advanced steam technology (sometimes known as Modern Steam) reflects an approach to the technical development of the steam engine intended for a wider variety of applications than has recently been the case. Particular attention has been given to the long-term endemic problems that have led to the demise of steam power in a commercial environment; these include excessive pollution, maintenance costs, labour intensive operation, low power/weight ratio, low overall thermal efficiency... This applies particularly to medium and small-scale installations where steam power has generally now been superseded by the internal combustion engine or by electrical power drawn from the National Grid. The proposed steam engines may be for stationary, road, rail or marine use.

The Argentinian engineer Livio Dante Porta in the development of "Stephensonian" railway locomotives incorporating advanced steam technology was a precursor of this movement from 1948^[1]. Where possible Porta much preferred to design new locomotives, but more often in practice he was forced to radically update old ones to incorporate the new technology.

Contents 1 Achieving the ends 1.1 Carbon neutrality 1.2 Potential solutions offered by advanced steam technology 2 History 3 Current projects 3.1 Small-scale stationary plant 3.2 Small ship auxiliaries/large portable generators 3.3 Small fixed stationary plant 3.4 Automotive uses 3.5 Rail use 3.5.1 Fireless locomotives 4 References

[edit] Achieving the ends

The Sir Biscoe Tritton Lecture, read by Roger Waller, of the DLM company [1] to the Institute of Mechanical Engineers in 2003^[2] gives an idea of how these problems are currently being addressed. Waller refers mainly to some rack and pinion mountain railway locomotives that were newly built from 1992-98. They were developed for three companies in Switzerland and Austria and continue to work on two of these lines at present (2008). The new steam locomotives burn the same grade of light oil as their diesel counterparts and all demonstrate the same advantages of ready availability and reduced labour cost; at the same time they have been shown to procure greatly reduced air and ground pollution. Their economic superiority has meant that they have largely replaced the diesel locomotives and railcars previously operating the line; over which steam locomotives present the additional advantage of providing strong tourist attraction.

A parallel line of development was the return to steam power of the old Lake Geneva paddle steamer Montreux that had been refitted with a diesel-electric engine in the 1960s [2]. Economic aims similar to those achieved with the rack locomotives were pursued through automatic control of the light-oil-fired boiler and remote control of the engine from the bridge enabling the steam ship to be manned by the same number of personnel as a motor ship.

All this can be summed up as follows on the basis of the DLM company prospectus[3]:

Modern Steam stands for a new economic and ecologic steam technology, providing the following advantages:

• One-man operation for steam locomotives
• Automatic boiler and remote-controlled steam engine for ships
• Light-oil firing with clean combustion
• Low cost of ownership providing good return on investment
• High thermal efficiency of engine and boiler
• High-level insulation of boiler, steam engine and piping
• Modular concept and exchangeable parts
• Up-to-date bearing technology reducing maintenance and protecting the environment

- To which may be added:

• Ready availability for use
• Can also be used as part of a cogeneration system with a petrol, diesel or gas turbine engine
• Lends itself well to combined heat and power (CHP) operation
• Can exploit geothermal sources of steam

[edit] Carbon neutrality

A power unit based on advanced steam technology may produce smaller quantities of toxic products than a diesel engine of the same power but as with any heat engine that involves combustion, it will inevitably emit a quantity of the greenhouse gas carbon dioxide. However, significant reductions in other worrying pollutants such as CO and NO_x are achievable through the intrinsic nature of steam technology[4] without the need for add-ons such as filters etc or special preparation of fuel. If wood fuel is used then the system could, theoretically, be carbon neutral. The use of biofuel remains controversial; that said, liquid biofuels are easier to manufacture for steam plant than for diesels, as they do not demand the stringent fuel standards required to protect diesel injectors. It follows then that advanced steam technology may offer the potential to achieve carbon neutrality more easily and cheaply than with other types of heat engine.

[edit] Potential solutions offered by advanced steam technology

In principle with steam plant, combustion and power delivery can be considered as separate issues. Whilst high overall thermal efficiency may be difficult to achieve – largely due to the extra stage of generating a working fluid between combustion and power delivery, mainly attributable to leakages and heat losses^[3] – the separation of the processes gives the possibility of addressing specific problems at each stage without revising the whole system every time. For instance the boiler/steam generator can be adapted to any heat source, whether obtained from solid, liquid or gaseous fuel, and can furthermore successfully exploit waste heat; whatever the choice, it will have no direct effect on the design of the engine unit as that only ever has to deal with steam, independently of the means that may have been employed to produce it.

[edit] History

Although most references to "Modern Steam" apply to developments since the 1970s, certain aspects of advanced steam technology can be discerned throughout the twentieth century, notably as regards automatic boiler control along with rapid steam raising from cold. From 1922 Abner Doble developed an electro-mechanical system that reacted simultaneously to steam temperature and pressure, starting and stopping the feed pumps whilst igniting and cutting out the burner according to boiler pressure.^[4] The contraflow monotube boiler had a working pressure of from 750 psi (5.17 MPa) to 1,200 psi (8.27 MPa) but contained so little water in circulation as to present no risk of explosion. This type of boiler was continuously developed in the USA, Britain and Germany throughout the 1930s and into the 1950s for use in cars, buses, trucks, railcars, shunting locomotives (US; switchers) a speedboat and a small aeroplane.

[edit] Current projects

[edit] Small-scale stationary plant

This mainly includes combined electrical generation and heating systems for private homes and small villages burning wood or bamboo chips. This is intended to replace 2-stroke donkey engines and small diesel power plants. Drastic reduction in noise level is one immediate benefit of a steam-powered small plant.

Ted Pritchard, Melbourne, Australia was intensively developing this type of unit from 2002 until his death in 2007 and the company Pritchard Power[5] intends to have a test unit in operation in 2008.

Until 2006, a German company called Enginion was also actively developing a Steamcell, a micro CHP unit about the size of a PC tower for domestic use. It seems that now (2008) it has merged with another Berlin company called AMOVIS [6]

A similar unit is marketed by Powertherm[7], a subsidiary of Spilling (see below).

[edit] Small ship auxiliaries/large portable generators

Once again quiet operation is the immediate benefit to be sought in this field, a potential recognised by Ted Pritchard; although nothing of note has yet appeared.

[edit] Small fixed stationary plant

The Spilling company produces a variety of small fixed stationary plant adapted to biomass combustion or power derived from waste heat or pressure recovery. [8] [9]

[edit] Automotive uses

During the first 1970s oil crisis, a number of investigations into steam technology were initiated by large automobile corporations although as the crisis died down, impetus was soon lost.

Ted Pritchard's[10] main field of research from the late 1950s through the Sixties and into the Seventies was the building of several efficient steam power units working on the uniflow system adapted to a small truck and two cars. One of the cars was achieving the lowest emissions figures of that time.

IAV, a Berlin-based R&D company that eventually developed the Steamcell, previously during the 1990s was working on the single-cylinder ZEE (Zero Emissions Engine, followed by the compact 3-cylinder EZEE (Equal-to-Zero-Emissions-Engine)[11] designed to fit under the bonnet (US hood) of a Skoda Fabia small family saloon. All these engines made heavy use of non-flaming ceramic heat cells both for the steam generator and at strategic boost points where steam was injected into the cylinder(s).

[edit] Rail use

• No. 52 8055 [12]

• The 5AT project [13]

Both 52 8055 and the proposed 5AT are of conventional layout, with the cab at the back, but other approaches are possible, especially with liquid fuel firing. For example:

• Cab forward type. This is a well-tried design with the potential for a large power output and it would give the driver a good view of the road ahead. Being single-ended, it would require to be turned on a Turntable (railroad) or be able to run round a convenient triangular junction.

• Garratt type. Another well-tried design with large power potential. Probably the best all-rounder. Could be modified by shortening the water tanks and adding a cab at each end to give the driver a good view in either direction.

• A design mounted on power bogies with compact water-tube boiler similar to Sentinel designs of the 1930s. This would give a compact, double-ended, locomotive but would require considerable development work.

[edit] Fireless locomotives

Another proposal for advanced steam technology is to revive the fireless locomotive, which runs on stored steam independently pre-generated.

[edit] References