Electric heating – Inductive heating – With heat exchange
Reissue Patent
2000-06-30
2002-07-23
Leung, Philip H. (Department: 3742)
Electric heating
Inductive heating
With heat exchange
C219S629000, C219S656000, C392S450000
Reissue Patent
active
RE037800
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a novel and useful steam generating system.
Steam is currently generated from liquid water by the use of oil, gas, coal, or other fuel in pressurized heat exchanged vessels. The pressure within such vessels normally runs 20 to 60 atmospheres. These prior steam generators are systems typically found on ocean going vessels and are quite large and cumbersome.
Natural gas fired or resistance electric heater systems have also been devised to produce superheated steam. Such systems are generally slow and inefficient.
In the past, induction heaters have been employed in furnaces to heat a metallic charge within a refractory crucible. Such furnaces are surrounded by a water cooled copper coil which receives power in the form of alternating current varying from 60 hertz to 500,000 hertz, or even higher frequencies which are derived from oscillators. Essentially, the molten charge within such induction furnace is heated by the interaction of eddy currents produced by a high frequency field. Moreover, the molten charge is considered to be the secondary of a transformer.
Unfortunately, the past systems have either required extensive and expensive equipment to produce superheated steam at very high pressures.
A steam generating system which produces superheated steam at or near atmospheric pressure would be a notable advance in the industrial arts.
SUMMARY OF THE INVENTION
In accordance with the present invention a novel and useful steam generating system is herein provided.
The steam generating system includes a first container which is provided with a first chamber for a liquid to be converted into steam. Such liquid may be water, ammonia, and the like. The chamber includes an inlet and an outlet. A reservoir of water communicates with the inlet of the first container such that liquid is provided therein at a steady rate, commensurate with the generation of steam within the container. The container also includes a tank wall portion or shell which is capable of being heated by electrically induced eddy currents. In most cases, the wall portion may be a metallic member such as copper, silver, aluminum, and the like. However, other materials may be employed which are capable of performing this function. In certain cases, metallic shells having a mask of other metallic materials may be employed. For example, a combination of a copper shell and an iron mask suffices, in this regard.
The system of the present invention also includes a first coil which at least partially surrounds the first container. The first coil may be a metallic member or one which is composed of a material which conducts electricity and is capable of producing a field around the container. The first coil may also be cooled by the passage of liquid therethrough. In this respect, such cooling helps maintain the strength of the electromagnetic field produced by the coil, which will be discussed hereinafter.
An insulation layer may also be found, in the present invention, sandwiched between the first coil and the wall portion of the first container. Such insulation layer is also cooled by the coil which is normally heated by heat radiating from the container. In essence, eddy currents created within the metallic tank by the electro-magnetic field produced by the coil heats the tank through the Joule effect. Radiated heat from the tank travels inwardly and heats upon the liquid within the chamber into steam. The steam is raised to a desired temperature for use. In certain cases, steam may be superheated within the first container.
First electric means generates a magnetic field at the first coil and an eddy current at the first container tank wall portion. The first electric means in the form of a high frequency AC power source produces a frequency which may be typically
250,000
25
kilohertz. However, any high frequency can be utilized in the power source of the present invention.
A second container is also employed in one of the embodiments of the present invention. Again, the second container is similarly constructed to the first container. That is, the second container includes a chamber, an inlet, and outlet, and a tank wall portion capable of being heated by an induction eddy current. A second coil surrounds the second chamber and is connected to second electric means for generating a field in the second coil and an eddy current at the second container. Conduit means transports steam from the first container outlet to the second container inlet. The induction heating accomplished in the second container superheats steam at approximately atmospheric pressure. Thus, superheated steam passes from the second container and may be employed to heat any item such as foodstuffs, metals, and the like.
It may be apparent that a novel and useful steam generating system has been described.
It is therefore an object of the present invention to produce a steam generating system which capable of producing superheated steam at or about atmospheric pressure.
Another object of the present invention is to provide a steam generating system which employs induction heating and avoids the expense and bulk of equipment used in prior superheated steam generating systems.
Another object of the present invention is to provide a steam generating system which is compact and may be easily used in confined spaces.
A further advantage of the present invention is to provide a steam generating system which is highly efficient and uses an induction and heating element having a high frequency power source.
Another object of the present invention is to provide a steam generating system which eliminates fire hazards, since the outer surfaces of the equipment employed in the present invention are normally cool to the touch.
The invention possesses other objects and advantages especially as concerns particular characteristics and features thereof which will become apparent as the specification continues.
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Daihan Co., Ltd.
Leung Philip H.
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