US-12624665-B2 - Purge system for dual-fuel gas turbine engine

US12624665B2US 12624665 B2US12624665 B2US 12624665B2US-12624665-B2

Abstract

A dual-fuel turbine engine is a type of turbine engine that can operate using two different fuel sources, such as liquid fuel (e.g., diesel) and natural gas. For liquid fuels, the turbine engine includes a primary line to facilitate engine startup and a secondary line to modify power output. Generally, the turbine engine only uses one type of fuel for combustion at a time. The fuel lines and passages in the fuel nozzles that carry the unused fuel source should preferably be purged and sealed by a purging system to reduce coking. However, conventional purge systems typically purge and seal only the secondary line for liquid fuels. As a result, the passages in the fuel nozzles connected to the primary line are prone to coking. To address this problem, a purge system is disclosed that purges and seals the primary line and, optionally, the secondary line.

Inventors

Vinayak Barve
David Plaza
Alex Starr
Joseph McMurry
Mike Yarnold
Christopher Beebe
Yanxia Sun

Assignees

VERICOR POWER SYSTEMS LLC

Dates

Publication Date: 20260512
Application Date: 20230906

Claims (14)

1 . A dual-fuel turbine engine configured to receive liquid fuel and natural gas, wherein, during operation of the dual-fuel turbine engine, only one of the liquid fuel or the natural gas is used for combustion and the dual-fuel turbine engine is further configured to switch between the liquid fuel and the natural gas, the dual-fuel turbine engine comprising: a fuel manifold having a first passage to carry a first portion of the liquid fuel, a second passage to carry a second portion of the liquid fuel, and a third passage to carry the natural gas; a natural gas intake system, fluidically coupled to the fuel manifold, to provide the natural gas; a liquid fuel intake system to provide the liquid fuel; a primary line network, fluidically coupled to the liquid fuel intake system and the fuel manifold, to carry the first portion of the liquid fuel; a secondary line network, fluidically coupled to the liquid fuel intake system and the fuel manifold, to carry the second portion of the liquid fuel; and a purge system, fluidically coupled to the primary line network, the secondary line network, and the third passage, to continuously provide a purging fluid, the purge system comprising a purge dividing fitting fluidically coupled to a primary liquid fuel dividing fitting of the primary line network and to a secondary liquid fuel dividing fitting of the secondary line network, wherein when the natural gas is used for combustion, the purge system flows the purging fluid through the first passage via the primary line network and the second passage via the secondary line network simultaneously; and wherein when the liquid fuel is used for combustion, the purge system flows the purging fluid through the third passage.
2 . The dual-fuel turbine engine of claim 1 , wherein: the primary liquid fuel dividing fitting comprises a first port, a second port, a third port, and a fourth port; the primary line network further comprises: a first primary line fluidically coupled to the liquid fuel intake system and the first port of the primary liquid fuel dividing fitting; and a second primary line fluidically coupled to the second port of the primary liquid fuel dividing fitting and the fuel manifold; the third port of the primary liquid fuel dividing fitting is fluidically coupled directly to the fuel manifold; and the purge dividing fitting is fluidically coupled to the fourth port of the primary liquid fuel dividing fitting.
3 . The dual-fuel turbine engine of claim 1 , wherein the purge system comprises: a valve fluidically coupled to a purge source, the first passage, the second passage, and the third passage; and a switch, operably coupled to the valve, to actuate the valve in response to a signal from a control system of the dual-fuel turbine engine.
4 . The dual-fuel turbine engine of claim 1 , wherein the purge system is configured to flow the purging fluid at a pressure of about 200 psig to about 250 psig.
5 . The dual-fuel turbine engine of claim 4 , wherein the purge system is configured to flow the purging fluid at a flow rate equal to or greater than 3 standard cubic feet per minute (SCFM).
6 . A method of operating a dual-fuel turbine engine configured to receive liquid fuel and gaseous fuel, the dual-fuel turbine engine comprising: a fuel manifold having a first passage to carry a first portion of the liquid fuel, a second passage to carry a second portion of the liquid fuel, and a third passage to carry the gaseous fuel, a primary line network connecting a liquid fuel source to the first passage of the fuel manifold via a first passage, a secondary line network connecting the liquid fuel source to the second passage of the fuel manifold via a second passage, and a gaseous fuel intake system connecting to the third passage of the fuel manifold via a third passage, and a purge system fluidly coupled to the primary line network, the secondary line network, and the third passage and comprising a purge dividing fitting fluidically coupled to a primary liquid fuel dividing fitting of the primary line network and to a secondary liquid fuel dividing fitting of the secondary line network, the method comprising: supplying the first portion of the liquid fuel from the liquid fuel source to the first passage of the fuel manifold via the primary line network and the first passage to facilitate startup of the dual-fuel turbine engine; supplying the second portion of the liquid fuel to the second passage of the fuel manifold via the secondary line network and the second passage to fuel the dual-fuel turbine engine; switching from the liquid fuel to gaseous fuel for fueling the dual-fuel turbine engine; and continuously flowing a purging fluid through the first passage via the purge dividing fitting and the primary liquid fuel dividing fitting of the primary line network and through the second passage via the purge dividing fitting and the secondary liquid fuel dividing fitting of the secondary line network while fueling the dual-fuel turbine engine with the gaseous fuel from the gaseous fuel intake system via the third passage that receives the gaseous fuel from the gaseous fuel intake system; and continuously flowing the purging fluid through the third passage when the liquid fuel is used for combustion.
7 . The method of claim 6 , wherein flowing the purging fluid through the first passage and the second passage occurs simultaneously.
8 . The method of claim 6 , further comprising: flowing the purging fluid through the first passage and the second passage at different flow rates and/or different flow pressures while fueling the dual-fuel turbine engine with the gaseous fuel.
9 . A dual-fuel turbine engine comprising: a fuel manifold to combust liquid fuel or gaseous fuel; a liquid fuel intake system, in fluid communication with the fuel manifold, to supply a first portion of the liquid fuel to the fuel manifold via a first liquid fuel dividing fitting and a first passage of the fuel manifold for start-up of the dual-fuel turbine engine and to supply a second portion of the liquid fuel to the fuel manifold via a second liquid fuel dividing fitting and a second passage of the fuel manifold for powering the dual-fuel turbine engine; a gaseous fuel intake system, in fluid communication with the fuel manifold, to supply the gaseous fuel to the fuel manifold via a third passage of the fuel manifold; and a purge system, in fluid communication with the fuel manifold, to continuously purge (i) the first passage via a purge dividing fitting fluidically coupled to the first liquid fuel dividing fitting and (ii) the second passage of the fuel manifold with purging fluid via the purge dividing fitting and the second liquid fuel dividing fitting while the gaseous fuel intake system supplies the gaseous fuel to the fuel manifold via the third passage of the fuel manifold and to continuously purge the third passage of the fuel manifold with the purging fluid while the liquid fuel intake system supplies the first portion of the liquid fuel to the fuel manifold via the first passage and the second portion of the liquid fuel to the fuel manifold via the second passage.
10 . The dual-fuel turbine engine of claim 9 , wherein the purge system comprises: a valve configured to connect to a purge source; and a switch, operably coupled to the valve, to actuate the valve in response to a signal from a control system of the dual-fuel turbine engine.
11 . The dual-fuel turbine engine of claim 9 , wherein the purge system is configured to flow the purging fluid through the first passage and the second passage at different flow rates and/or different flow pressures while the gaseous fuel intake system supplies the gaseous fuel to the fuel manifold via the third passage of the fuel manifold.
12 . The dual-fuel turbine engine of claim 9 , wherein the first liquid fuel dividing fitting is a four-port fitting.
13 . The dual-fuel turbine engine of claim 9 , wherein the purge system is configured to flow the purging fluid at a pressure of about 200 psig to about 250 psig.
14 . The dual-fuel turbine engine of claim 13 , wherein the purge system flows the purging fluid at a flow rate equal to or greater than 3 standard cubic feet per minute (SCFM).

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) This application claims the priority benefit, under 35 U.S.C. 119 (e), of U.S. Application No. 63/374,671, filed Sep. 6, 2022, which is incorporated herein by reference in its entirety for all purposes. JOINT RESEARCH AGREEMENT This application is subject to a joint research agreement between BJ Services, LLC, and Vericor Power Systems LLC. BACKGROUND A turbine engine is a thermomechanical device used in various power generation and mechanical drive applications, such as oil or natural gas extraction, jet propulsion, and the generation of electricity. Generally, a turbine engine operates by combusting fuel in a combustion chamber to produce a continuous stream of hot gas which, in turn, flows through and drives a downstream turbine. The turbine is mechanically coupled to an upstream compressor. Thus, a portion of the energy of the hot gas is used to drive the compressor and generate pressurized air for combustion with the remaining energy available for different uses depending on the application (e.g., providing thrust or driving an electrical generator). Over the years, turbine engines have been developed to operate using various liquid and gaseous fuels, such as liquified petroleum gas, kerosene, diesel, syngas, or natural gas. These fuels, however, are often subject to supply disruptions and/or market volatility. Moreover, turbine engines should also meet strict emissions regulations, which are changing as industries move towards decreasing carbon emissions to reduce the effects of climate change. These aspects coupled with the relatively long operating lifetime of conventional turbine engines (e.g., years, decades) have given rise to turbine engines that can operate using different types of fuels from different fuel sources (also referred to as a “fuel flexible turbine engine”). Compared to turbine engines that operate using only a single fuel source, a fuel flexible turbine engine is less likely to experience disruptions in operation due to sudden shortages in a particular type of fuel source. Fuel flexible turbine engines also allow operators to transition more easily from one type of fuel to another type of fuel (e.g., from liquid fuel to natural gas) particularly as regulations are introduced over time that mandate certain fuel sources over others. One example of a fuel flexible turbine engine is a dual-fuel turbine engine, which can use two different types of fuel for combustion, such as a liquid fuel (e.g., diesel) and a gaseous fuel (e.g., natural gas). A dual-fuel turbine engine typically operates using only one type of fuel at a time, but can switch between the two fuel sources during operation. In some instances, the changeover between a first fuel source (e.g., a liquid fuel) and a second fuel source (e.g., natural gas) can occur while the turbine engine is operating under full load. Said in another way, the turbine engine can remain in operation when switching between different fuels. This can be accomplished, in part, by incorporating fuel nozzles with multiple passages that supply different fuels to the combustion chamber of the turbine engine so that at least one type of fuel can be continually supplied for combustion. Some dual-fuel turbines can further utilize co-firing where two (or more) fuel sources are supplied simultaneously for combustion. SUMMARY Many dual-fuel turbine engines, particularly those used for oil and natural gas extraction, use cold fuel nozzles to inject fuel into their combustion chambers. Cold fuel nozzles are fuel nozzles that are partially disposed within the combustion chamber and operate at temperatures lower than the temperature of the hot gas produced within the combustion chamber. For turbine engines that operate using only a single fuel source, the fuel is transported at relatively cooler temperatures compared to the hot gases produced within the combustion chamber. Thus, the temperature of the fuel nozzle and, in particular, the passage of the fuel nozzle is typically maintained by continuously flowing fuel through the passage of the nozzle. For dual-fuel turbine engines, however, cold fuel nozzles are often prone to coking. Specifically, the unused passages of the fuel nozzle (i.e., the passages that do not supply a fuel currently being combusted by the turbine engine) may be exposed to the high temperature gases produced within the combustion chamber. This can lead to undesirable heating of the fuel nozzle that damages the nozzle. Additionally, excessive heating may vaporize any unburnt fuel or fuel residue within the unused passages of the fuel nozzle resulting in the formation of hard carbon deposits. Unburnt fuel or fuel residue vaporized near the fuel nozzle may also flow into the unused passages of the fuel nozzle resulting in hard carbon deposits on the inner surfaces of the fuel nozzle and/or fuel lines connected to the fuel nozzle. These deposits can impede and, in some instances, block the flow of fuel