Fluid sprinkling – spraying – and diffusing – Combining of separately supplied fluids – Including whirler device to induce fluid rotation
Reexamination Certificate
2002-09-12
2004-06-29
Doerrler, William C. (Department: 3744)
Fluid sprinkling, spraying, and diffusing
Combining of separately supplied fluids
Including whirler device to induce fluid rotation
C239S406000, C239S432000, C239S596000
Reexamination Certificate
active
06755359
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
This invention relates generally to apparatuses and methods for injecting fluids and more specifically to an injector and associated method for injecting combustion fluids into a combustion chamber.
2) Description of Related Art
The combustion of carbon-based compounds, or carbonaceous fuels, is widely used for generating kinetic and electrical power. In one typical electric generation system, a carbonaceous fuel such as natural gas is mixed with an oxidizer and combusted in a combustion device called a gas generator. The resulting combusted gas is discharged to, and used to rotate, a turbine, which is mechanically coupled to an electric generator. The combusted gas is often discharged to one or more additional combustion devices, called reheaters, where the combusted gas is mixed with additional fuel and/or oxidizer for subsequent combustion.
Gas generators and reheaters are generally similar combustion devices, but gas generators have traditionally been used as initial combustion devices and reheaters have traditionally been used as secondary combustion devices that recombust a gas after the gas has gone through an initial combustion device. Gas generators typically combust at least some liquid combustion components, e.g. liquid water, while reheaters typically combust only gases including, for example, steam. Therefore, the volumetric expansion of the combustion gases in a typical gas generator is higher than that of a reheater. Further, the pressure drop across the injector system of a gas generator is typically higher than that of a reheater.
The combustion in both gas generators and reheaters results in high temperatures and pressures. In some systems, pure oxygen is used as the oxidizer to eliminate the production of nitric oxides (NOx) and sulfur oxides (SOx) that typically result from combustion with air. The temperature in such an oxygen-fed system can be especially high, sometimes exceeding 5000° F. Such extreme conditions increase the stress on components in and around the combustion chambers, increasing the likelihood of failure of such components and decreasing their useful lives accordingly.
Injectors are used to inject the combustion components of fuel, oxidizer, and/or recycled gases into the combustion chambers of the gas generator and reheaters. Because of their position proximate to the combustion chambers, the injectors are subjected to the extreme temperatures of the combustion chamber. Additionally, the injectors may be heated by the passage of preheated combustion components therethrough. Failure of the injectors due to the resulting thermal stress caused by overheating increases operating costs, increases the likelihood of machine downtime, and presents an increased danger of worker injury and equipment damage.
One proposed injector incorporates a mixer for combining a coolant with the fuel before the fuel is combusted. For example, U.S. Pat. No. 6,206,684 to Mueggenburg describes an injector assembly
10
that includes two mixers
30
,
80
. The first mixer
30
mixes an oxidizer with a fuel, and the second mixer
80
mixes coolant water with the prior mixed fuel and oxidizer. The mixture then flows through a face
121
to a combustion chamber
12
for combustion. The coolant water reduces the temperature of combustion of the fuel, easing the stress on the system components. One danger presented by such a design is the possibility of “flashback,” or the combustion flame advancing from the combustion chamber into the injector. Flashback is unlikely in an injector outlet that has a diameter smaller than the mixture's “quenching distance”. Thus, flashback can be prevented by limiting the size of the injectors. Undesirably, however, a greater number of small injectors is required to maintain a specified flow rate of the combustion mixture. The increased number of injectors complicates the assembly. Small injectors are also typically less space-efficient because the small injectors require more space on the face than would a lesser number of large injectors that achieve the same flow rate. Space on the face is limited, so devoting more space to the injectors leaves less space for other uses, such as devices for injecting coolant into the combustion chamber.
Because sufficient quantities of coolant sometimes cannot be injected from the face, coolant must be injected further downstream. The injection of liquid coolant presents a danger to turbine blades located downstream from the combustion device. If the coolant is not fully vaporized before reaching the turbine, droplets of liquid coolant can damage the turbine blades. Injection of large volumes of a liquid coolant near the turbine blades can increase the likelihood of droplets progressing to the turbine blades, and decrease the useful life of the blades. Turbine blades are sometimes protected by splash plates, which provide a physical barrier to prevent the progression of liquid coolant. However, splash plates add complication to the system, requiring additional service and increasing the cost of the system. Splash plates can also interfere with the flow of gas through the combustion chamber and turbine, and are sometimes not fully effective in protecting the turbine blades.
Additionally, small injectors are subject to further complications due to their size. For example, small passages and outlets in the injectors can become blocked by particulates present in the fuel, oxidizer, or coolant. Thus, the reactants must be carefully filtered before passing through the injector. The need for filters also increases the complexity and cost of the system, as well as the likelihood of failure.
Thus, there exists a need for an apparatus and method for injecting fluid components of combustion into a combustion chamber. The injector and method should prevent liquid water from progressing to downstream turbine blades and should minimize the likelihood of flashback. Preferably, the injector should not be overly complex and should not require stringent filtering of the combustion components. The injector and method should be adaptable for use with gas generators and reheaters of various sizes. Further, the injector and method should facilitate efficient combustion, even at varying flow rates and limit the temperature of the injector to decrease thermal stress, likelihood of failure, and operating costs.
BRIEF SUMMARY OF THE INVENTION
The present invention provides an injection system, an injector, and an associated method for injecting combustion fluids into a combustion chamber. Each injector injects an oxidizing fluid formed from a mixture of steam and oxygen to impinge on, and mix with, a stream of fuel in a combustion chamber. Mixing the oxidizing fluid and fuel in the combustion chamber decreases the likelihood of flashback, even with relatively large streams of fuel. Any number of injectors can be included on a faceplate of an injection system for a gas generator or reheater, and the thorough mixing provided by the injector also increases the efficiency of the combustion, even at low flow rates. Further, the flexibility in the size of the injectors also increases the potentially available space on the faceplate for coolant injectors. Locating the coolant injectors at the faceplate reduces the likelihood of coolant droplets progressing through the combustion chamber to the turbine.
According to one embodiment of the present invention, the injection system includes a first faceplate and a plurality of injectors extending through the first faceplate. The faceplate has an inlet side and an outlet side that faces the combustion chamber. Each of the injectors has a fuel bore that extends from a fuel bore inlet to a fuel bore outlet located at an outlet side of the injector. The diameter of the fuel bore can converge in a direction from the fuel bore inlet to the fuel bore outlet. A swirler chamber defined by the injector has at least one inlet for receiving steam and oxygen, which are preferably mixed before entering the inlet. A converging channel extends fro
Jensen Robert J.
Matthews David R.
Sprouse Kenneth M.
Alston & Bird LLP
Doerrler William C.
The Boeing Company
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