Power plants – Combustion products used as motive fluid
Reexamination Certificate
1999-08-17
2001-07-24
Kim, Ted (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S039350, C060S279000, C060S737000
Reexamination Certificate
active
06263660
ABSTRACT:
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
TECHNICAL FIELD OF THE INVENTION
My invention relates to an apparatus for high efficiency fuel-air mixing, and to the novel combination of such fuel-air mixing arrangements with the low pressure supply of fuel to a rotary ramjet engine power plant. More particularly, my invention relates to a unique combination of structures in the inlet air supply for a rotary ramjet engine, as particularly advantageous in achieving thorough lean pre-mixing of fuel and air which is necessary to minimize emission of nitrogen oxides.
BACKGROUND OF THE INVENTION
A continuing demand exists for a simple, highly efficient and inexpensive thermal power plant which can reliably provide low cost electrical and mechanical power. This is because many electrical and/or mechanical power plants could substantially benefit economically from a prime mover that offers significantly improved cycle efficiencies. This is particularly true in medium size power plants—generally in the 10 to 100 megawatt range—which are used in many industrial applications, including stationary electric power generating units, rail locomotives, and marine power systems.
Medium sized power plants are also well suited for industrial and utility cogeneration facilities. Such facilities are increasingly employed to service thermal power needs while simultaneously generating electrical power in a cost effective manner. Power plant designs which are now commonly utilized in co-generation applications include (a) gas turbines, driven by the combustion of natural gas, fuel oil, or other fuels, which capture the thermal and kinetic energy from the combustion gases, (b) steam turbines, driven by the steam which is generated in boilers from the combustion of coal, fuel oil, natural gas, solid waste, or other fuels, and (c) large scale reciprocating engines, usually diesel cycle and typically fired with fuel oils.
Of the currently available power plant technologies, diesel fueled reciprocating and advanced aeroderivative gas turbine engines have the highest efficiency levels. Unfortunately, with respect to the reciprocating engines, at higher power output levels, the size of the individual engine components required become almost unmanageably large, and as a result, commercial use of single unit reciprocating engine systems in larger sizes has been minimal.
Gas turbines perform more reliably than reciprocating engines, and thus are in widespread use. However, because gas turbines are only moderately efficient in converting fuel to electrical energy, gas turbine powered plants are most effectively employed in co-generation systems where both electrical and thermal energy can be utilized. In that manner, the gas turbine efficiency can be counterbalanced by using the thermal energy to increase the overall cycle efficiency.
In any event, and particularly in view of reduced governmental regulation in the sale of electrical power, it can be appreciated that significant cost reduction in electrical power generation would be desirable. This objective can be most effectively accomplished by generating electrical power at higher overall cycle efficiency than is achieved with technology currently utilized for power generation.
One of the technical challenges in providing a high efficiency combustion engine is the ability to achieve low emissions of undesirable nitrogen oxides, i.e., to minimize “NOx” production. Also, to achieve stable, uniform combustion temperatures, it is desirable to provide a method to easily control and maintain uniformity in concentration of fuel in fuel-air mixtures. This is particularly helpful in avoidance of flame temperature variations, to thus avoid hot spots and accompanying potential adverse effects with respect to the hot zone cooling technology and metallurgy.
In gas turbine technology, it is well known that combustion at lean fuel-air ratios is effective in reducing the formation of oxides of nitrogen (“NOx”). However, since gas turbines inject fuel into combustors after the inlet combustion air has been compressed, the fuel must be introduced to the gas turbine combustor under pressure. Also, pressure in such fuel supply line is often utilized to assist mixing of the fuel with the compressed air, by inserting a high momentum fuel jet into the combustion chamber, so that in the resulting mixture, the incoming fuel is very well mixed with the compressed air. However, if through mixing did not occur, the result would be a fuel-air mixture which at various points was richer than optimum for achieving low NOx performance.
In contrast, in my rotary ramjet based power plant, the necessary inlet air compression to support combustion in the ramjet occurs only along the inlet ramp of the ramjet. In my ramjet engine, it is unnecessary to expend energy for the compression of gaseous fuels. Therefore, high pressure fuel, and accompanying high momentum fuel injection jets, are not normally available to promote mixing of the fuel with the air, since the compression of gaseous fuels is not otherwise necessary.
It is therefore desirable to provide a fuel-air mixing housing capable of reliably and uniformly mixing low pressure fuel and the supplied inlet air to provide a uniform, consistent composition lean fuel-air mixture.
SUMMARY OF THE INVENTION
I have now invented a novel, improved rotary ramjet based power plant which uses as one important component an air-fuel pre-mix housing utilizing fuel supply structures in the shape of low aerodynamic drag stators with strategically located fuel injection outlets, and with vortex generators to generate transverse momentum as necessary to assure thorough fuel-air mixing. In such apparatus, fuel air mixing is conducted at or near ambient pressure, and at the ambient (or any desired) incoming temperature. Thus, fuel-air mixing is reliably completed prior to being fed to the combustor. This apparatus, and the method used to reliably design such apparatus, result in the uniform, lean fuel-air pre-mix conditions necessary to reliably achieve low NOx emissions during power plant operation.
Also, by use of a metered fuel feed apparatus, the power output of the ramjet power plant can be turned down as necessary to maintain the desired rotating velocity. In this manner, a constant rotating velocity can be achieved, as is necessary in synchronous power generation apparatus.
To achieve the desired power plant operational parameters, I have now developed a novel fuel-air mixing housing which uses an axial supply fan design and which introduces a lean, uniformly mixed fuel-air mixture to a transverse mounted ramjet engine configuration. This apparatus overcomes some specific problems inherent in the heretofore known apparatus and methods that are known to me and which have heretofore been proposed for the application of ramjet technology to stationary power generation equipment. Of primary importance, I have now developed a simple, low speed, essentially ambient pressure air supply apparatus which can deliver a stabilized, smoothly flowing oxidant carrier gas to a housing for thorough mixing with a gaseous fuel which is supplied at low pressure. Preferably, fuel is injected at relatively low velocity into the air supply stream, and the fuel and air are thoroughly mixed by using a plurality of vortex generators to create swirling vortices, so that a uniformly mixed fuel-oxidant mixture is supplied to the ramjet inlet. Resultingly, efficient and clean combustion of the supplied fuel is achieved.
More specifically, my novel fuel-air pre-mix housing receives an inlet carrier gas such as air which carries an oxidant such as oxygen, and thoroughly mixes the carrier gas with a selected fuel such as natural gas. The housing, and the process employed therein, tho
Goodloe, Jr. R. Reams
Kim Ted
Ramgen Power Systems, Inc.
LandOfFree
Apparatus and method for fuel-air mixing before supply of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for fuel-air mixing before supply of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for fuel-air mixing before supply of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2543914