Patent Application
20160341429
The subject matter disclosed herein relates to gas turbine engines and, more particularly, to a liquid fuel supply system, as well as a method of supplying liquid fuel in a gas turbine engine.
During various operating conditions of a dual fuel gas turbine engine, it is required that liquid fuel is inhibited from entering a liquid fuel manifold. Examples of such operations include during gas fuel operation of the gas turbine engine or during a purge credit mode of the combustor assembly. This is done to protect the liquid fuel combustor nozzles and liquid fuel mixing valves. To block the liquid fuel from entering these locations, a valve assembly is employed upstream of these components and downstream of a liquid fuel supply.
A fluid may be routed to the liquid fuel manifold to pressurize the manifold when it is desirable to prevent liquid fuel from entering the fuel manifold or passing further downstream to the liquid fuel combustor nozzles. Upon initiation of a liquid fuel operation of the gas turbine engine, liquid fuel is to be routed to the combustor. Prior to doing so, the fluid disposed in the liquid fuel manifold must be removed to provide a clear path for the liquid fuel. Typically, this is done by completely draining the fluid from liquid fuel manifold and subsequently filling the manifold with liquid fuel. Unfortunately, the fluid draining procedure may account for a significant amount of time that is allotted for the transition to the liquid fuel operation, with the possibility of even exceeding the allotted time. Therefore, the delay associated with draining the fluid is an undesirable aspect for operators of gas turbine engines.
According to one aspect of the disclosure, a method of supplying liquid fuel in a gas turbine engine is provided and includes sealing a fuel manifold with a fluid in the fuel manifold. The method also includes initiating routing of a liquid fuel from a liquid fuel supply structure to the fuel manifold. The method further includes displacing the fluid disposed in the fuel manifold with the liquid fuel. The method yet further includes routing the liquid fuel and the fluid into a combustor.
According to another aspect of the disclosure, a method of supplying liquid fuel in a gas turbine engine is provided and includes sealing a fuel manifold with a water in the fuel manifold. The method also includes initiating routing of a liquid fuel from a liquid fuel supply structure to the fuel manifold. The method further includes displacing the water disposed in the fuel manifold with the liquid fuel, wherein displacing the water comprises routing the liquid fuel to the fuel manifold at varying flow rates. The method yet further includes routing the liquid fuel and the water into a combustor.
According to yet another aspect of the disclosure, a fuel supply system for a gas turbine engine includes a liquid fuel supply structure containing a liquid fuel. The fuel supply system also includes a combustor. The fuel supply system further includes a fuel manifold fluidly coupled to the liquid fuel supply structure to receive the liquid fuel and fluidly coupled to the combustor for selective distribution of the liquid fuel to the combustor. The fuel supply system yet further includes a liquid supply structure containing a liquid different from the liquid fuel, the liquid supply structure fluidly coupled to the fuel manifold for routing of the liquid to the fuel manifold, wherein the liquid fuel and the liquid are routed to the combustor upon initiation of routing the liquid fuel to the combustor.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the disclosure, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the disclosure, together with advantages and features, by way of example with reference to the drawings.
Referring to
In operation, air flows into the compressor 12 and is compressed into a high pressure gas. The high pressure gas is supplied to the combustor assembly 14 and mixed with fuel, for example natural gas, fuel oil, process gas and/or synthetic gas (syngas), in the combustor chamber 18. The fuel/air or combustible mixture ignites to form a high pressure, high temperature combustion gas stream, which is channeled to the turbine 24 and converted from thermal energy to mechanical, rotational energy. As will be appreciated from the description herein, the fuel provided is a liquid fuel, but it is to be appreciated that embodiments of the gas turbine engine 10 employ both liquid fuel and gas fuel, which may be employed during different operating conditions.
Referring now to
The valves 38, 39 are in the closed condition when the gas turbine engine 10 is operating in a condition other than liquid fuel operation. For example, this may occur during gas fuel operation of the gas turbine engine 10 or during a purge credit mode of the combustor assembly 14.
To reduce or eliminate the likelihood that liquid fuel undesirably leaks into or through the liquid fuel manifold 34 during a closed condition of the valves 38, 39, pressurization of the liquid fuel manifold 34 is provided with a purge system 40. The purge system 40 is fluidly coupled to the combustor assembly 14 and is configured to purge various portions of the combustor assembly 14 with a liquid, such as water, via a water manifold. More specifically, the water is demineralized water in certain embodiments. The purge system 40 includes a fluid supply line 42 (e.g., water supply line) that is fluidly coupled to a fluid supply 44 (e.g., water supply) and the liquid fuel manifold 34. A fluid valve 52 is provided between the fluid supply 44 and the liquid fuel manifold 34 to control the flow rate of fluid to the liquid fuel manifold 34. The fluid valve 52 (e.g., water valve) transitions between an open state and a closed state to selectively control the flow rate of the fluid to the liquid fuel manifold 34.
The fluid is pumped to the liquid fuel manifold 34 to pressurize the components therein. Pressurization opposes any leaked portion of the liquid fuel that tends to pass through the valve 38, thereby reducing the likelihood of ingress of the liquid fuel to the liquid fuel manifold 34 from upstream locations along the liquid fuel piping arrangement 36. To effectively seal the liquid fuel manifold 34 from the leaked portion of liquid fuel, the fluid pumped to the liquid fuel manifold 34 must exceed the internal pressure of the liquid fuel piping arrangement 36, which may vary depending upon the particular application and operating conditions.
In
During a gas turbine engine starting operation or transfer to a liquid fuel operation, the fluid disposed in the liquid fuel manifold 34 must be removed to clear a path for the liquid fuel that is to be routed to the combustor assembly 14. Rather than wasting time with draining the fluid, the embodiments described herein simply employ the pressure of the liquid fuel to displace the fluid. This is done by opening the valves 38, 39. The liquid fuel and the fluid are then routed into the combustor assembly 14. Elimination or reduction of the draining process advantageously reduces the time required for initiation of a liquid fuel operation of the gas turbine engine 10, whether during a fast start of the gas turbine engine 10 or during a transition from gas fuel operation to liquid fuel operation. While it is contemplated that some of the fluid may be drained, typically all of the fluid is routed to the combustor assembly 14.
As described above, routing of the liquid fuel to the liquid fuel manifold 34 comprises opening the valve 38. When done in conjunction with opening of valve 39, the liquid fuel and the fluid are routed to the combustor assembly 14. The valve 38 is configured to allow for control of the flow rate of the liquid fuel. In one embodiment, the flow rate is constant over the entire fluid removal process. However, in some embodiments it is advantageous to vary the flow rate of the liquid fuel during initiation of the liquid fuel operating condition. The advantages may be associated with the fuel supply profile required and/or with displacement characteristics of the fluid from the liquid fuel manifold 34. For example,
Advantageously, start or transition time for a liquid fuel operation is reduced by avoiding the need to completely drain the liquid fuel piping arrangement 36, including the liquid fuel manifold 34, of the fluid disposed therein during sealing of the arrangement. In some applications, operators of the gas turbine engine 10 are sensitive to this response time to the degree of seconds. Therefore, even small amounts of reduced time periods are greatly desired by operators in some instances.
While the disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that aspects of the disclosure may include only some of the described embodiments. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
