Power plants – Motive fluid energized by externally applied heat – Power system involving change of state
Patent
1996-02-23
1999-05-04
Kamen, Noah P.
Power plants
Motive fluid energized by externally applied heat
Power system involving change of state
60668, 12223522, 122248, 180 652, 180310, F01K 2500
Patent
active
058990720
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention covers a steam generator and a steam turbine driving unit containing the generator which can be operated in a more advantageous way than conventional combustion engines, without air contamination, especially if hydrogen is used for fuel, because in this case the carbon dioxide emission accompanying the firing of hydrocarbons is avoided.
The most widely used fuels are hydrocarbons, primarily crude oil derivates. Consequently, oil reserves are expected to be exhausted sometime in the middle of the next century, according to prevailing estimates. Another disadvantage is the carbon dioxide emission, the harmful consequences of which are increasingly grave. With higher firing temperatures, the further drawback of nitrogen oxide emission arises, increasingly jeopardizing life and health.
To reduce the above indicated problems, the use of hydrogen as fuel has been considered for a long time. Hydrogen is available in unlimited quantities, and returns to its former state after firing. Hydrogen is the cleanest fuel, can be produced and used without losses, in a cycle, without emitting any substances than could be harmful to the environment. As the firing temperature can be reduced with suitable control, the production of nitrogen oxides can be reduced to a minimum level.
The general use of hydrogen as fuel requires the construction of various projects to resolve the task related to the production, storage and transportation of large quantities.
However, the use of hydrogen also creates a number of problems. At an environmental temperature, gaseous molecular hydrogen does not penetrate metals immediately. Hydrogen in atomic form is more dangerous. Atomic hydrogen can be generated at a temperature of above 430.degree. F., in the presence of humidity, in case of corrosion and electrolysis, as well as a higher hydrogen pressure. At higher temperatures, the effect of hydrogen consists of a surface or inner decarbonization. The surface decarbonization occurs above 1050.degree. F., and this reaction is caused by water vapor. During the inner decarbonization, hydrogen penetrates into steel at temperatures above 430.degree. F., reducing the iron carbide to metallic iron by means of an internal reaction, creating methane. The products of the reaction gather at grain boundaries and in small crevices, causing the reduction of plasticity. In graver cases, they bring about the growth of local, internal pressures, and consequently the formation of blisters or fractures. (See P. Webb; C. Gupta: metals in hydrogen environment, Chem. Eng. October, 1984). The stress type fractures caused by hydrogen are sometimes mentioned as a delayed rigid fracture caused by hydrogen or an internal hydrogenous rigidity. This used to happen when the metal was exposed for a long period of time to tensile stresses caused by load lower than the yield limit.
At lower temperatures, below 430.degree. C., brittleness or the formation of blisters takes place. The brittleness or rigidity is caused by the hydrogen penetrating into the metal, reducing the plasticity and tensile strength of the metal.
The effect of hydrogen on metals can be reversible or irreversible. In case of an irreversible rigidity, the absorption of hydrogen is accompanied by a damage arising in the metal structure, which remains even when the last traces of the hydrogen itself have left the metal. One example is copper, in which hydrogen, having diffused into the metal at a temperature of above 300.degree. C., enters into reaction with the inclusions, whereby water vapor and metallic copper are produced. The increased pressure associated with high temperature is sufficient for the inclusions to widen themselves, making the texture of the metal porous and deteriorating its strength. The reversible transformations can be reversed by driving out the hydrogen, and the original value of plasticity can be regained.
Hydrogen as a fuel has very good characteristics: its combustion temperature and heating value are high, it is ab
REFERENCES:
patent: 3139866 (1964-07-01), Lumm et al.
patent: 5092127 (1992-03-01), Miller
patent: 5385214 (1995-01-01), Spurgeon
patent: 5513600 (1996-05-01), Teves
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