Steam generator injector

Combustion – Process of combustion or burner operation – Feeding flame modifying additive

Reexamination Certificate

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Details

C431S002000, C431S350000, C239S008000, C239S419300, C239S559000, C239S416100

Reexamination Certificate

active

06206684

ABSTRACT:

FIELD OF THE INVENTION
The following invention relates to a system for injecting combustible mixtures into a combustion chamber. More specifically, this invention relates to a steam generator injector designed to inject a thoroughly premixed combination of oxidizer, fuel, and coolant water into a combustion chamber which has steam and carbon dioxide as its primary combustion species.
BACKGROUND OF THE INVENTION
Injecting combustible fluids and coolants into combustion chambers has long been a common practice in the prior art. Typically, fuel and oxidizer reactants are brought to an injector face by separate flow paths. The reactant flow paths are designed to control and meter the fluids prior to their exit from orifices in the injector face. Internal geometry, spacing, and number of the orifices are configured to promote efficient mixing as the combustible fluids flow into a combustion chamber and travel away from the injector face. An ignition source then ignites the combustible mixture of reactants and large quantities of heat are released.
The large heat release in the combustion chamber usually makes it necessary to actively cool its walls to prevent combustion chamber damage. This is typically accomplished by enveloping the parts of the chamber to be cooled with a coolant, generally a fuel or water. Often more cooling capacity is necessary, as when stoichiometric mixture ratios cause extremely high combustion temperatures. In this case, coolant is injected directly into the combustion chamber and mixes with the combustion fluids. Cooling systems such as that disclosed by Walker (U.S. Pat. No. 2,770,097 are of this type. are of this type.
There are several drawbacks to the prior art approach. First, stoichiometric mixture ratios are generally not used because of the excessive heat generated (as well as pollutant generation problems), thereby limiting the heat release of the reactants below their full potential. An important reason reactants are not combusted at stoichiometric mixture ratios is that high levels of cooling are required to prevent damage to the combustion chamber and injector face. Another important reason is that a catastrophic explosion could result if the combustion flame propagated back into the injector body.
The second drawback to the prior art approach is that the mixture ratio distribution within the chamber is often not uniform. The non-uniformity occurs because machining tolerances permit variations in the orifice geometry and spacing and because manifold velocities are often not uniform. This leads to streaking of the combustion walls and necessitates the use of a chamber wall film coolant. The coolant, generally fuel, reduces the overall combustion efficiency of the process and results in using more fuel than otherwise would be necessary.
Beichel (U.S. Pat. No. 5,709,077) teaches a prior art system which disclose combusting hydrocarbon fuel with oxygen at a stoichiometric ratio to produce a high temperature water and carbon dioxide working fluid without any pollutants. This system teaches water delivery to cool the combustion reaction somewhat. However, no system for injecting the reactants and water into the combustion chamber is shown other than direct entry into the combustion chamber as disclosed in the prior art.
Accordingly, a need exists for an apparatus and system that thoroughly mixes the combustible fluids and allows combustion of fuels at stoichiometric mixture ratios without damaging the combustion chamber or incurring undesirable combustion inefficiencies.
SUMMARY OF THE INVENTION
The steam generator injector apparatus and system of this invention solves the problems associated with extremely high combustion temperatures, upstream flame propagation, and non-uniform mixture ratio distribution. It does so by reducing combustion temperatures of reactants having stoichiometric mixture ratios and by eliminating non-uniform mixture ratio distribution. Specifically, the injector system has two primary design features that provide these benefits. The first design feature is that the injector system thoroughly premixes the combustion reactants before they enter the injector manifold and orifices. This essentially eliminates non uniform mixture ratio distribution. Machining errors, non-uniform manifold velocities, and orifice distribution and geometries on the injector face have minimal negative impact because the present invention does not rely on these features to promote mixing.
The other distinguishing design feature of the present invention is that coolant is mixed with the reactants prior to injection into the combustion chamber. Coolant streams are injected perpendicular to streams of premixed reactants and in a manner that induces flow to ensure thorough mixing. The combination of reactants and coolants are injected into the combustion chamber where the combination is ignited. The coolant reduces what would otherwise be extremely high combustion temperatures throughout the combustion zone by absorbing a portion of the released heat. By contrast, prior art does not control the heat release of the combusting reactants. Instead, the walls of the combustion chamber are protected from the high temperature by regenerative cooling, film cooling along the interior combustion chamber walls, or both. The latter result in combustion inefficiencies not found in the present invention.
A typical operation of the system is as follows. Continuous sources of fuel, oxidizer, and coolant flow are made available for use in the injector. Typical examples are methane, oxygen, and water as the fuel, oxidizer, and coolant, respectively. Fuel and oxidizer are drawn from separate sources through individual feed lines. They are then brought together inside the injector assembly to a first mixing region at desired proportions ranging from fuel rich to oxidizer rich. In the preferred embodiment of this invention, the mixing area consists of a stack of platelets that bring the reactants together in an inner chamber in such a manner as to induce substantially complete mixing of the reactants. The substantially mixed reactants are then channeled to a second mixing region.
Concurrently, coolant is drawn from its source through a feed line into and along an injector face. The coolant reduces the temperature of the face during combustion to acceptable levels for the particular injector face material used. The coolant passes from the injector face into the second mixing region. In this region the coolant is atomized and brought together with the substantially mixed reactants and the fluids are blended into a single mixture. The velocity of the substantially mixed reactants causes the water droplets formed by the self impinging water streams to shear and further promote atomization of the coolant immediately prior to injecting into the combustion chamber. This combined mixture is channeled through holes in the injector face that open into the combustion chamber. The combined mixture goes into the combustion chamber where combustion is initiated by an igniter.
OBJECTS OF THE INVENTION
Accordingly, a primary object of the present invention is to provide an injector assembly that premixes reactants from the injector upstream of the injector face.
Another object of the present invention is to blend coolant and reactants before injection into a combustion chamber.
Another object of the present invention is to reduce combustion temperatures of reactants being combusted in stoichiometric proportions.
Another object of the present invention is to promote safe combustion of reactants at stoichiometric mixture ratios.
Another object of the present invention is to prevent uneven mixture ratio combustion that results in local hot zones along the combustion chamber walls.
Another object of the present invention is to prevent damage to combustion chambers.
Another object of the present invention is to reduce combustion temperatures of reactants.
Another object of the present invention is to prevent adverse effects on combustion chambers due to geometric variations in injector orifice g

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