Systems and methods for igniting and operating a gas turbine engine with alternative fuels

Abstract

The present invention discloses a power generation system (100), which includes a combustion system (108), a liquid supply system (104), and a steam supply system (106). The combustion system (108) is configured to generate electricity by burning an alternative fuel. The liquid supply system (104) is configured to direct the liquid alternative fuel to the combustion system (108). The steam supply system (106) is configured to direct the vapor alternative fuel to the combustion system (108). The combustion system (108) is ignited by burning the liquid alternative fuel from the liquid supply system (104) and is operated by burning the vapor alternative fuel from the steam supply system (106).

Description

Background Art

[0001] The field of the present disclosure relates generally to gas turbine engines and, more particularly, to systems and methods for igniting and operating gas turbine engines using alternative fuels.

[0002] In at least some known rotating machines, energy is extracted from the combustion of alternative fuels such as biodiesel, alcohol-based fuels (methanol, ethanol, etc.), bioalcohol, vegetable oils, and / or other biomass fuels. Alternative fuels may be cheaper, more readily available, and may be used for carbon offsets in some jurisdictions. In addition, burning alternative fuels can reduce emissions and increase the operating range of rotating machinery because the boiling point of alternative fuels can be lower than that of conventional fuels.

[0003] However, rotary machinery burning alternative fuels is typically ignited and started using conventional fuels because alternative fuels are more volatile than conventional fuels. Specifically, because at least some known alternative fuels vaporize at lower temperatures than conventional fuels, rotary machinery burning alternative fuels is first ignited using liquid conventional fuel and then transitions to burning the alternative fuel after ignition. Therefore, it is desirable to ignite and operate gas turbine engines using alternative fuels. Summary of the Invention

[0004] In one aspect, a power generation system is provided. The power generation system includes a combustion system, a liquid supply system, and a steam supply system. The combustion system is configured to generate electricity by burning an alternative fuel. The liquid supply system is configured to direct the liquid alternative fuel to the combustion system. The steam supply system is configured to direct the vapor alternative fuel to the combustion system. The combustion system ignites by burning the liquid alternative fuel from the liquid supply system and operates by burning the vapor alternative fuel from the steam supply system.

[0005] In another aspect, a method for generating electricity using a power generation system is provided. The power generation system includes a combustion system, a liquid supply system, and a steam supply system. The steam supply system includes a heat recovery steam generator and a vaporization system. The method includes directing a first liquid alternative fuel from the liquid supply system to the combustion system. The method also includes using the first liquid alternative fuel from the liquid supply system to ignite the combustion system by burning the first liquid alternative fuel to generate electricity and exhaust gas. The method also includes directing the exhaust gas from the combustion system to the heat recovery steam generator. The method also includes using the exhaust gas to heat a heat exchange medium within the heat recovery steam generator. The method also includes directing the heat exchange medium from the heat recovery steam generator to the vaporization system. The method also includes using the heat exchange medium to vaporize a second liquid alternative fuel to generate a vapor alternative fuel. The method also includes directing the vapor alternative fuel to the combustion system. The method also includes operating the combustion system by burning the vapor alternative fuel.

[0006] In another aspect, a method for generating electricity using a power generation system is provided. The power generation system includes a combustion system and a steam supply system. The method includes generating steam using an auxiliary boiler. The method also includes directing the steam from the auxiliary boiler to a vaporization system. The method also includes vaporizing a liquid alternative fuel using the steam to generate vapor alternative fuel. The method also includes directing the vapor alternative fuel to the combustion system. The method also includes igniting and operating the combustion system by combusting the vapor alternative fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters refer to like parts throughout, and in which:

[0008] Figure 1 is a flow chart diagram of an exemplary power generation system;

[0009] Figure 2 is available for Figure 1 A schematic diagram of an exemplary combustion system in a power generation system is shown;

[0010] Figure 3 is a flow chart diagram of another exemplary power generation system;

[0011] Figure 4 is a flow chart diagram of another exemplary power generation system;

[0012] Figure 5 is a flow chart diagram of another exemplary power generation system;

[0013] Figure 6 is used Figure 1 A flowchart of an exemplary method for generating power by a power generation system; and

[0014] Figure 7 is used Figure 5 A flow chart of an exemplary method for generating power using a power generation system.

[0015] Unless otherwise indicated, the drawings provided herein are intended to illustrate features of the embodiments of the present disclosure. It is believed that these features are applicable to a variety of systems including one or more embodiments of the present disclosure. Therefore, the drawings are not intended to include all conventional features required for practicing the embodiments disclosed herein that are known to those of ordinary skill in the art. DETAILED DESCRIPTION

[0016] In the following description and claims, reference will be made to a number of terms which shall be defined to have the following meanings.

[0017] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0018] Unless otherwise indicated, approximate language as used herein, such as "substantially", "substantially" and "about" indicate as those of ordinary skill in the art will recognize that the terms so modified may apply only to an approximate degree, rather than an absolute or perfect degree. Therefore, the value modified by one or more terms (such as "about", "approximately" and "substantially") is not limited to the specified exact value. In at least some cases, approximate language can correspond to the precision of the instrument used to measure the value. Here and throughout the specification and claims, range limitations can be identified. Unless otherwise indicated by the context or language, these ranges can be combined and / or interchangeable, and include all subranges contained therein. In addition, unless otherwise indicated, the terms "first", "second" etc. are only used as marks in this article, and are not intended to impose order, position or hierarchical requirements on the items referred to by these terms. In addition, for example, the reference to the "second" item does not require or exclude the existence of, for example, the "first" or lower numbered item or the "third" or higher numbered item.

[0019] As used herein, the terms "axial" and "axially" refer to directions and orientations that extend substantially parallel to the longitudinal axis of a rotary machine. Additionally, the terms "radial" and "radially" refer to directions and orientations that extend substantially perpendicular to the longitudinal axis of a rotary machine. Additionally, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations that extend in an arc around the longitudinal axis of a rotary machine. Further, as used herein, the term "upstream" refers to the front end or inlet end of a rotary machine, and the term "downstream" refers to the rear end or outlet end of a rotary machine.

[0020] The system described herein relates to a power generation system that is ignited and operated using alternative fuels. Specifically, the power generation system described herein includes a storage and distribution system, a liquid supply system, a steam supply system, and a combustion system. The storage and distribution system stores a certain volume of alternative fuel, such as ethanol, and directs a portion of the stored ethanol to the liquid supply system and the steam supply system. The liquid supply system receives liquid ethanol from the storage and distribution system and directs the liquid ethanol to the combustion system. The steam supply system receives ethanol from the storage and distribution system and vaporizes the liquid ethanol into vaporized ethanol that is directed to the combustion system. The combustion system generates electricity by igniting the liquid ethanol from the liquid supply system. Exhaust gas from the combustion system is then directed to a heat recovery steam generator within the steam supply system, wherein the heat recovery steam generator generates steam that is directed to a heat exchanger within the steam supply system. The heat exchanger vaporizes the liquid ethanol into vaporized ethanol that is directed to the combustion system.

[0021] During the transition, the combustion system begins to burn liquid ethanol from the liquid supply system and vaporized ethanol from the vapor supply system. More specifically, the liquid supply system gradually reduces the volume of liquid ethanol supplied to the combustion system, and the vapor supply system increases the volume of vaporized ethanol supplied to the combustion system until the combustion system burns only vaporized ethanol. Thus, the power generation system described herein ignites and subsequently operates using the alternative fuel. Generally, power generation systems that use alternative fuels to generate electricity emit fewer greenhouse gases and have greater operational flexibility than power generation systems that use conventional fuels to generate electricity. Therefore, the power generation system described herein is beneficial for reducing fossil fuel emissions by generating electricity using alternative fuels such as ethanol and has greater operational flexibility.

[0022] Figure 1 It is a flow chart of an exemplary power generation system 100 using alternative fuels to generate electricity. In an exemplary embodiment, the alternative fuel is ethanol. However, the alternative fuel can be any other type of unconventional liquid fuel that enables system 100 to operate as described herein, including but not limited to biodiesel, alcohol-based fuel (methanol, ethanol, etc.), bioalcohol, vegetable oil and / or other biomass fuels. As used herein, conventional fuel is generally fossil fuel, such as but not limited to petroleum products, coal and / or natural gas. In addition, although system 100 is configured to use alternative fuels to generate electricity, system 100 also can use conventional fuels to generate electricity, and the conventional fuel is such as but not limited to petroleum products, coal and / or natural gas (methane).

[0023] In the exemplary embodiment, power generation system 100 includes a storage and distribution system 102, a liquid supply system 104, a vapor supply system 106, and a combustion system 108. Storage and distribution system 102 stores a volume of ethanol and directs a portion of the stored ethanol to liquid supply system 104 and vapor supply system 106. Liquid supply system 104 receives liquid ethanol from storage and distribution system 102 and directs the liquid ethanol to combustion system 108. Vapor supply system 106 receives liquid ethanol from storage and distribution system 102, vaporizes the liquid ethanol into vaporous ethanol, and directs the vaporous ethanol to combustion system 108. In addition, vapor supply system 106 may also direct vaporous methane to combustion system 108. Combustion system 108 generates electricity by combusting liquid ethanol from liquid supply system 104, vaporous ethanol from vapor supply system 106, and / or a different fuel from liquid supply system 104 or vapor supply system 106.

[0024] In the exemplary embodiment, storage and dispensing system 102 includes an ethanol storage system 110, a first pump system 112, a first filtration system 114, and a first flow measurement system 116. Ethanol storage system 110 includes at least one storage tank (not shown) that receives and stores a volume of ethanol. Ethanol storage system 110 may receive ethanol from, for example, a pipeline, a nearby production facility, a ship, and / or a tanker truck.

[0025] First pump system 112 transfers ethanol from ethanol storage system 110 to first filtration system 114, to first flow measurement system 116, to liquid supply system 104, and / or to vapor supply system 106. In the exemplary embodiment, first pump system 112 comprises a pump. In alternative embodiments, first pump system 112 comprises any type of fluid dynamic device that enables storage and dispensing system 102 to operate as described herein.

[0026] In the exemplary embodiment, first filtration system 114 filters particulates and / or debris from the ethanol received from first pump system 112 to facilitate protecting downstream equipment from such particulates and / or debris that may be entrained within the ethanol received from first pump system 112. First filtration system 114 may include any type of filter that enables storage and dispensing system 102 to operate as described herein.

[0027] In the exemplary embodiment, first flow measurement system 116 measures ethanol from first pump system 112 to better control liquid supply system 104 and / or vapor supply system 106. First flow measurement system 116 may include any type of flow meter that enables storage and dispensing system 102 to operate as described herein. Ethanol is directed from first flow measurement system 116 to liquid supply system 104 and / or vapor supply system 106.

[0028] In the exemplary embodiment, liquid supply system 104 includes a second pump system 118, a second filtration system 120, a second flow measurement system 122, and a flow control and distribution system 124. Second pump system 118 transfers ethanol from first flow measurement system 116 to second filtration system 120, to second flow measurement system 122, to flow control and distribution system 124, and / or to combustion system 108. In the exemplary embodiment, second pump system 118 includes a pump. In alternative embodiments, second pump system 118 includes any type of fluid dynamic device that enables liquid supply system 104 to operate as described herein.

[0029] In an exemplary embodiment, second filtration system 120 filters particulates and / or debris from the ethanol received from second pump system 118 to protect downstream equipment from such particulates and / or debris that may be entrained within the ethanol received from second pump system 118. Second filtration system 120 may include any type of filter that enables liquid supply system 104 to operate as described herein. Liquid supply system 104 may also include a safety shut-off valve (SSOV) to protect equipment within liquid supply system 104 and / or combustion system 108.

[0030] In the exemplary embodiment, a second flow measurement system 122 measures ethanol from the second pump system 118 in order to control the liquid supply system 104 and / or the combustion system 108. The second flow measurement system 122 may include any type of flow meter that enables the liquid supply system 104 to operate as described herein. In the exemplary embodiment, a flow control and distribution system 124 controls the flow of ethanol from the flow measurement system 122 to the combustion system 108. The flow control and distribution system 124 includes valves, actuators, and / or other flow control devices that control the delivery or flow rate of ethanol to the combustion system 108. The ethanol is directed from the flow control and distribution system 124 to the combustion system 108.

[0031] In the exemplary embodiment, vapor supply system 106 includes a third pump system 126, a vaporization system 128, a methane supply system 130, a heat recovery steam generator (HRSG) 132, an inertial separator 134, a third flow measurement system 136, and a gas control system 138. Third pump system 126 transfers ethanol from first flow measurement system 116 to vaporization system 128, to inertial separator 134, to third flow measurement system 136, to gas control system 138, and / or to combustion system 108. In the exemplary embodiment, third pump system 126 includes a pump. In alternative embodiments, third pump system 126 includes any type of fluid dynamic device that enables vapor supply system 106 to operate as described herein.

[0032] In an exemplary embodiment, vaporization system 128 vaporizes ethanol from third pump system 126. Vaporization system 128 includes at least one heat exchanger 140 that transfers heat from the heat exchange medium of HRSG 132 to the ethanol from third pump system 126 to vaporize the ethanol from third pump system 126. In an alternative embodiment, vaporization system 128 includes a plurality of heat exchangers 140 that vaporize ethanol from third pump system 126. In an exemplary embodiment, components of vaporization system 128 downstream of heat exchanger 140 are heat traced (e.g., Figure 1) to preheat equipment within vaporization system 128 to receive vaporized ethanol from heat exchanger 140. Heat traces within vaporization system 128 may also be used to preheat equipment within vaporization system 128 to receive methane from methane supply system 130.

[0033] In the exemplary embodiment, methane supply system 130 directs methane to vaporization system 128 downstream of heat exchanger 140. The heating value of methane is similar to that of ethanol, enabling combustion system 108 to burn either ethanol vapor or methane. Therefore, if ethanol is unavailable, methane can be used as an alternative fuel source. Therefore, if ethanol is unavailable, methane supply system 130 supplies methane to combustion system 108. Furthermore, methane supply system 130 can supply methane to supplement vaporized ethanol. Thus, methane supply system 130 increases the operational flexibility of power generation system 100.

[0034] In the exemplary embodiment, HRSG 132 receives exhaust gas from combustion system 108 and transfers heat from the exhaust gas to a heat exchange medium. HRSG 132 also directs the heat exchange medium to heat exchanger 140 and receives heat exchange medium from heat exchanger 140. In the exemplary embodiment, HRSG 132 includes a heat exchanger that recovers heat from the exhaust gas in combustion system 108 and transfers the recovered heat to the heat exchange medium. In the exemplary embodiment, the heat exchange medium includes liquid water and / or steam. However, the heat exchange medium may include any type of heat transfer fluid that enables steam supply system 106 to operate as described herein.

[0035] HRSG 132 and heat exchanger 140 form a closed loop circuit that directs a heat exchange medium from HRSG 132 to heat exchanger 140, and from heat exchanger 140 back to HRSG 132. Thus, HRSG 132 increases the temperature of the heat exchange medium by transferring heat from the exhaust gas to the heat exchange medium, and heat exchanger 140 decreases the temperature of the heat exchange medium by transferring heat from the heat exchange medium to ethanol to vaporize the ethanol.

[0036] In an exemplary embodiment, inertial separator 134 separates liquid that may be entrained in the vaporized ethanol from the vaporized ethanol. The vaporized ethanol from vaporization system 128 may include liquid entrained in the vaporized ethanol. Specifically, due to a fault within heat exchanger 140, droplets of liquid ethanol may be entrained in the vaporized ethanol and / or heat exchange medium may leak into the vaporized ethanol. In an exemplary embodiment, inertial separator 134 comprises a centrifugal separator. However, inertial separator 134 may include any other type of separator that enables vapor supply system 106 to operate as described herein. In an exemplary embodiment, components of inertial separator 134 downstream of heat exchanger 140 are heat traced (e.g., Figure 1 ) to a preheating device within inertial separator 134 to receive vaporized ethanol from heat exchanger 140.

[0037] In the exemplary embodiment, third flow measurement system 136 measures the vaporized ethanol from inertial separator 134 to control vapor supply system 106 and / or combustion system 108. Third flow measurement system 136 measures the flow of vaporized ethanol but does not control the flow of vaporized ethanol. The flow measurement is used to tabulate or total flow consumption when operating with only ethanol vapor, or can be used as a method to control the mixture or blend ratio during operation using a mixture of methane vapor and ethanol vapor. Third flow measurement system 136 may include any type of flow meter that enables vapor supply system 106 to operate as described herein.

[0038] In the exemplary embodiment, gas control system 138 controls the flow of vaporized ethanol from third flow measurement system 136 to combustion system 108. Gas control system 138 includes valves, actuators, and / or other flow control devices oriented to control the flow of vaporized ethanol to combustion system 108. Vaporized ethanol is directed from gas control system 138 to combustion system 108. In the exemplary embodiment, components of third flow measurement system 136 and gas control system 138 downstream of heat exchanger 140 are heat traced (e.g., Figure 1 ) to a third flow measurement system 136 and a preheating device within a gas control system 138 to receive vaporized ethanol from a heat exchanger 140 .

[0039] In the exemplary embodiment, combustion system 108 is a gas turbine engine. Alternatively, combustion system 108 may be any other turbine engine and / or rotary machine, including but not limited to a gas turbofan aircraft engine and / or other aircraft engine.

[0040] Figure 2is an enlarged schematic diagram of an exemplary combustion system 108. In the exemplary embodiment, combustion system 108 includes an intake section 202, a compressor section 204 downstream of intake section 202, a combustor section 206 downstream of compressor section 204, a turbine section 208 downstream of combustor section 206, and an exhaust section 210 downstream of turbine section 208. Turbine section 208 is coupled to compressor section 204 via a rotor shaft 212. It should be noted that, as used herein, the term "coupled" is not limited to direct mechanical, thermal, electrical, and / or fluidic connections between components, but may also include indirect mechanical, thermal, electrical, and / or fluidic connections between multiple components.

[0041] In the exemplary embodiment, combustor section 206 includes a plurality of burners 214 and a plurality of fuel nozzles (not shown). Combustor section 206 is coupled to compressor section 204 such that each burner 214 is in fluid communication with compressor section 204. Rotor shaft 212 is also coupled to a load 216, such as, but not limited to, a generator and / or a mechanical drive application. In the exemplary embodiment, each of compressor section 204 and turbine section 208 includes at least one rotor assembly 218 coupled to rotor shaft 212.

[0042] In operation, intake section 202 delivers air 220 toward compressor section 204. Compressor section 204 compresses intake air 220 to a higher pressure and then discharges compressed air 222 toward combustor section 206. Compressed air 222 is directed to combustor section 106, where it is mixed with ethanol from liquid supply system 104 and / or ethanol from steam supply system 106 and combusted to generate high-temperature combustion gases 224. More specifically, ethanol from liquid supply system 104 is directed to fuel nozzles at high pressure. The fuel nozzles atomize the ethanol from liquid supply system 104, causing the atomized ethanol to mix with compressed air 222. Combustion gases 224 are directed downstream toward turbine section 208 and impact turbine blades (not shown), converting thermal energy into mechanical rotational energy, which is used to drive rotor assembly 218 to rotate about longitudinal axis 226. Generally, combustor section 206 and turbine section 208 are referred to as the hot gas section of combustion system 108. The exhaust gas 228 is then discharged to the HRSG 132 via the exhaust section 210 .

[0043] During operation of power generation system 100, storage and distribution system 102 directs ethanol to liquid supply system 104, and liquid supply system 104 directs ethanol to combustion system 108. Liquid ethanol from liquid supply system 104 is used to ignite combustion system 108. Thus, combustion system 108 is started using an alternative fuel. Exhaust gas 228 from combustion system 108 is directed to HRSG 132. Once combustion system 108 reaches a minimum operating load for burning liquid ethanol, steam supply system 106 begins vaporizing ethanol and directing the vaporized ethanol to combustion system 108. That is, once the temperature of the exhaust gas is high enough to vaporize the ethanol, steam supply system 106 begins vaporizing ethanol and directing the vaporized ethanol to combustion system 108. Then, during a transition period, combustion system 108 begins combusting both liquid ethanol from liquid supply system 104 and vaporized ethanol from steam supply system 106. Liquid supply system 104 reduces the volume of liquid ethanol and vapor supply system 106 increases the volume of vaporized ethanol until combustion system 108 burns only vaporized ethanol. Thus, power generation system 100 ignites and operates combustion system 108 using the alternative fuel.

[0044] In an alternative operating mode, methane supply system 130 directs methane into vaporization system 128 downstream of heat exchanger 140, allowing the methane to mix with the vaporized ethanol. Thus, the methane supplements the vaporized ethanol, and combustion system 108 operates on a mixture of vaporized ethanol and methane. In another alternative operating mode, methane supply system 130 directs methane into vaporization system 128 downstream of heat exchanger 140, and vaporization system 128 does not vaporize ethanol. Thus, combustion system 108 operates solely on methane.

[0045] Figure 3 is a flow chart diagram of an exemplary power generation system 300 that generates electricity using an alternative fuel and is fired solely on methane. More specifically, combustion system 108 is fired solely on methane, enabling exhaust gas 228 to heat HRSG 132. HRSG 132 raises the temperature of the heat exchange medium by transferring heat from the exhaust gas to the heat exchange medium, and heat exchanger 140 lowers the temperature of the heat exchange medium by transferring heat from the heat exchange medium to ethanol, vaporizing the ethanol. Thus, the combustion of methane allows vaporization system 128 to begin producing vaporized ethanol. The vaporized ethanol is then blended with methane, and combustion system 108 begins operating on the blend of methane and vaporized ethanol. Combustion system 108 can either remain operating on the blend of methane and vaporized ethanol or switch to operating solely on vaporized ethanol.

[0046] Power generation system 300 is substantially similar to power generation system 100, except that in power generation system 300, liquid supply system 104, vaporization system 128, inertial separator 134, third flow measurement system 136, and gas control system 138 do not include heat tracing. Alternatively, power generation system 300 may include liquid supply system 104, but liquid supply system 104 is idle during operation of power generation system 300.

[0047] During operation of power generation system 300, methane is directed from methane supply system 130 to combustion system 108 through vaporization system 128, inertial separator 134, third flow measurement system 136, and gas control system 138. Combustion system 108 is ignited using the methane from methane supply system 130. Exhaust gas 228 from combustion system 108 is directed to HRSG 132.

[0048] Once combustion system 108 reaches its minimum operating load for burning methane, steam supply system 106 begins vaporizing ethanol and directing the vaporized ethanol to combustion system 108. That is, once the temperature of the exhaust gas is high enough to vaporize ethanol, steam supply system 106 begins vaporizing ethanol and directing the vaporized ethanol to combustion system 108. More specifically, steam supply system 106 mixes the vaporized ethanol with methane, and then, during a transition, combustion system 108 begins burning the mixture of methane from methane supply system 130 and vaporized ethanol from steam supply system 106. Methane supply system 130 reduces the volume of methane, and steam supply system 106 increases the volume of vaporized ethanol until combustion system 108 is burning only vaporized ethanol. Thus, power generation system 300 uses conventional fuel (e.g., methane) to ignite combustion system 108 and uses alternative fuel (e.g., vaporized ethanol) to operate combustion system 108.

[0049] Power generation system 300 may also include steam pipe 302 coupled to HRSG 132 and inertial separator 134. In some operating modes, the combustion of methane generates exhaust gas 228 that heats HRSG 132. HRSG 132 generates steam that is directed to inertial separator 134, third flow measurement system 136, and gas control system 138 to preheat equipment within inertial separator 134, third flow measurement system 136, and gas control system 138 to begin receiving vaporized ethanol from vaporization system 128.

[0050] Figure 4FIG2 is a flow chart of an exemplary power generation system 400 that generates electricity using an alternative fuel and is ignited using liquid ethanol. Power generation system 400 is substantially similar to power generation system 300, except that steam supply system 106 further includes an auxiliary boiler 402, and steam pipe 302 is coupled to HRSG 132, auxiliary boiler 402, and inertial separator 134. Liquid ethanol is used to ignite combustion system 108, and auxiliary boiler 402 preheats equipment within inertial separator 134, third flow measurement system 136, and gas control system 138 to receive vaporized ethanol from vaporization system 128.

[0051] While auxiliary boiler 402 preheats a portion of steam supply system 106, exhaust gas 228 heats HRSG 132. HRSG 132 raises the temperature of the heat exchange medium by transferring heat from the exhaust gas to the heat exchange medium, and heat exchanger 140 lowers the temperature of the heat exchange medium by transferring heat from the heat exchange medium to the ethanol, vaporizing the ethanol. Consequently, the combustion of the liquid ethanol allows vaporization system 128 to begin producing vaporized ethanol. The vaporized ethanol is then blended with the liquid ethanol, and combustion system 108 begins operating on the blend of liquid and vaporized ethanol. Utilizing auxiliary boiler 402 to preheat a portion of steam supply system 106 enables steam supply system 106 to quickly begin producing vaporized ethanol and quickly switch to operating solely on vaporized ethanol.

[0052] During operation of power generation system 400, steam pipe 302 directs steam from auxiliary boiler 402 and / or HRSG 132 to inertial separator 134. The steam preheats equipment within inertial separator 134, third flow measurement system 136, and gas control system 138 to receive vaporized ethanol from vaporization system 128. Auxiliary boiler 402 generates steam using electricity, combustion of natural gas, combustion of ethanol, and / or any other energy source. Storage and distribution system 102 then directs the ethanol to liquid supply system 104, and liquid supply system 104 directs the ethanol to combustion system 108. Liquid ethanol from liquid supply system 104 is used to ignite combustion system 108. Thus, combustion system 108 is started using alternative fuel. Exhaust gas 228 from combustion system 108 is directed to HRSG 132.

[0053] Once combustion system 108 reaches the minimum operating load for burning liquid ethanol, vapor supply system 106 begins vaporizing ethanol and directing the vaporized ethanol to combustion system 108. That is, once the temperature of the exhaust gas is high enough to vaporize ethanol, vapor supply system 106 begins vaporizing ethanol and directing the vaporized ethanol to combustion system 108. Then, during a transition period, combustion system 108 begins combusting liquid ethanol from liquid supply system 104 and vaporized ethanol from vapor supply system 106. Liquid supply system 104 reduces the volume of liquid ethanol, and vapor supply system 106 increases the volume of vaporized ethanol until combustion system 108 is burning only vaporized ethanol. Thus, power generation system 400 ignites and operates combustion system 108 using the alternative fuel.

[0054] During an alternative operating mode of power generation system 400, steam from auxiliary boiler 402 is directed into inertial separator 134, third flow measurement system 136, and gas control system 138 to preheat equipment within inertial separator 134, third flow measurement system 136, and gas control system 138. After auxiliary boiler 402 has preheated portions of steam supply system 106, methane is directed from methane supply system 130 through vaporization system 128, inertial separator 134, third flow measurement system 136, and gas control system 138 to combustion system 108. Combustion system 108 is ignited using the methane from methane supply system 130. Exhaust gas 228 from combustion system 108 is directed to HRSG 132.

[0055] Once combustion system 108 reaches its minimum operating load for burning methane, steam supply system 106 begins vaporizing ethanol and directing the vaporized ethanol to combustion system 108. That is, once the temperature of the exhaust gas is high enough to vaporize ethanol, steam supply system 106 begins vaporizing ethanol and directing the vaporized ethanol to combustion system 108. More specifically, steam supply system 106 mixes the vaporized ethanol with methane, and then, during a transition, combustion system 108 begins burning the mixture of methane from methane supply system 130 and vaporized ethanol from steam supply system 106. Methane supply system 130 reduces the volume of methane, and steam supply system 106 increases the volume of vaporized ethanol until combustion system 108 is burning only vaporized ethanol. Thus, power generation system 400 uses conventional fuel (e.g., methane) to ignite combustion system 108 and uses alternative fuel (e.g., vaporized ethanol) to operate combustion system 108.

[0056] Figure 5is a block diagram of an exemplary power generation system 500 for generating electricity using alternative fuels. Power generation system 500 is substantially similar to power generation system 400, except that steam supply system 106 further includes a steam or water supply line 502 coupled to auxiliary boiler 402 and heat exchanger 140 of vaporization system 128, and a steam or condensate return line 504 coupled to auxiliary boiler 402 and heat exchanger 140 of vaporization system 128. Steam or water supply line 502 directs steam or water from auxiliary boiler 402 to heat exchanger 140 of vaporization system 128 to vaporize ethanol from third pump system 126. Steam or condensate return line 504 directs steam or condensate from heat exchanger 140 of vaporization system 128 back to auxiliary boiler 402. Auxiliary boiler 402 generates steam using electricity, combustion of natural gas, combustion of ethanol, and / or any other energy source.

[0057] During operation of power generation system 500, steam from auxiliary boiler 402 is directed to heat exchanger 140 of vaporization system 128. Simultaneously, third pump system 126 pumps liquid ethanol to vaporization system 128, and steam from auxiliary boiler 402 vaporizes the liquid ethanol. Storage and distribution system 102 then directs the ethanol to liquid supply system 104, and liquid supply system 104 directs the ethanol to combustion system 108. Liquid ethanol from liquid supply system 104 is used to ignite combustion system 108. Thus, combustion system 108 is started using an alternative fuel. Then, during a transition period, combustion system 108 begins combusting liquid ethanol from liquid supply system 104 and vaporized ethanol from steam supply system 106. Liquid supply system 104 reduces the volume of liquid ethanol, and steam supply system 106 increases the volume of vaporized ethanol until combustion system 108 is combusting only vaporized ethanol. Exhaust gas 228 from combustion system 108 is directed to HRSG 132.

[0058] Once combustion system 108 reaches the minimum operating load for burning liquid ethanol, HRSG 132 begins directing steam to vaporization system 128, and auxiliary boiler 402 reduces steam production until HRSG 132 generates all the steam necessary to vaporize the liquid ethanol. Thus, power generation system 500 ignites and operates combustion system 108 using an alternative fuel.

[0059] During the alternative operating mode of power generation system 500, steam from auxiliary boiler 402 is directed through steam line 302 to inertial separator 134, third flow measurement system 136, and gas control system 138 to preheat the equipment within inertial separator 134, third flow measurement system 136, and gas control system 138. Steam from auxiliary boiler 402 is also directed to heat exchanger 140 of vaporization system 128 to vaporize ethanol from third pump system 126 using steam supply line 502. Steam supply system 106 vaporizes the ethanol and directs the vaporized ethanol to combustion system 108. Combustion system 108 is then ignited and operated using the vaporized ethanol from steam supply system 106. Thus, combustion system 108 is started using the vaporized alternative fuel. Exhaust gas 228 from combustion system 108 is directed to HRSG 132.

[0060] Once combustion system 108 reaches the minimum operating load for combusting vaporized ethanol, HRSG 132 begins directing steam to steam supply system 106. That is, once the temperature of the exhaust gas is high enough to vaporize ethanol, HRSG 132 begins directing steam to steam supply system 106, and steam supply system 106 begins vaporizing ethanol using steam from HRSG 132. Combustion system 108 then begins combusting the vaporized ethanol that has been vaporized using steam from HRSG 132 rather than from auxiliary boiler 402. Thus, power generation system 500 ignites and operates combustion system 108 using the vaporized alternative fuel.

[0061] Figure 6 Is to use the power generation system 100 ( Figure 1 106 . The power generation system 100 includes a combustion system 108, a liquid supply system 104, and a steam supply system 106. The steam supply system 106 includes a HRSG 132 and a vaporization system 128. In the exemplary embodiment, the method 600 includes directing 602 a first liquid alternative fuel from the liquid supply system 104 to the combustion system 108. The method 600 also includes igniting 604 the combustion system 108 with the first liquid alternative fuel from the liquid supply system 104 by combusting the first liquid alternative fuel. The combustion of the first liquid alternative fuel generates electricity and exhaust gas. The method 600 also includes directing 606 the exhaust gas from the combustion system 108 to the HRSG 132. The method 600 also includes heating 608 a heat exchange medium within the HRSG 132 using the exhaust gas. The method 600 also includes directing 610 the heat exchange medium from the HRSG 132 to the vaporization system 106. The method 600 also includes vaporizing 612 a second liquid alternative fuel using the heat exchange medium to generate a vaporized alternative fuel. The method 600 also includes directing 614 the vapor substitute fuel to the combustion system 108. The method 600 also includes operating 616 the combustion system 108 by combusting the vapor substitute fuel.

[0062] Figure 7 Is the use of power generation system 500 ( Figure 5 10. The power generation system 500 includes the combustion system 108 and the steam supply system 106. The steam supply system 106 includes the vaporization system 128 and the auxiliary boiler 402. The method 700 includes generating 702 steam using the auxiliary boiler 402. The method 700 also includes directing 704 the steam from the auxiliary boiler 402 to the vaporization system 106. The method 700 also includes vaporizing 706 a liquid substitute fuel using the steam to generate a vapor substitute fuel. The method 700 also includes directing 708 the vapor substitute fuel to the combustion system 108. The method 700 also includes igniting and operating 710 the combustion system 108 by combusting the vapor substitute fuel.

[0063] The above-mentioned power generation system ignites and operates using alternative fuels. Specifically, the power generation system described herein includes a storage and distribution system, a liquid supply system, a steam supply system, and a combustion system. The storage and distribution system stores a certain volume of alternative fuel, such as ethanol, and directs a portion of the stored ethanol to the liquid supply system and the steam supply system. The liquid supply system receives liquid ethanol from the storage and distribution system and directs the liquid ethanol to the combustion system. The steam supply system receives ethanol from the storage and distribution system and vaporizes the liquid ethanol into vaporized ethanol that is directed to the combustion system. The combustion system generates electricity by igniting the liquid ethanol from the liquid supply system. The exhaust gas from the combustion system is then directed to a heat recovery steam generator within the steam supply system, wherein the heat recovery steam generator generates steam, which is directed to a heat exchanger within the steam supply system. The heat exchanger vaporizes the liquid ethanol into vaporized ethanol that is directed to the combustion system.

[0064] The combustion system begins by burning liquid ethanol from the liquid supply system and, during the transition, operates using both liquid ethanol and vaporized ethanol from the vapor supply system. More specifically, the liquid supply system reduces the volume of liquid ethanol and the vapor supply system increases the volume of vaporized ethanol until the combustion system is burning only vaporized ethanol. Thus, the power generation system described herein ignites and subsequently operates using the alternative fuel. Generally, power generation systems that use alternative fuels to generate electricity emit fewer greenhouse gases and have greater operational flexibility than power generation systems that use conventional fuels to generate electricity. Therefore, the power generation system described herein is advantageous in reducing fossil fuel emissions and having greater operational flexibility by generating electricity using alternative fuels such as ethanol.

[0065] Among other things, exemplary technical effects of the systems and methods described herein include at least one of: (a) igniting a combustion system using a liquid alternative fuel; (b) igniting a combustion system using a vapor alternative fuel; and (c) operating a combustion system using a vapor alternative fuel.

[0066] Exemplary embodiments of systems and methods for generating electricity using alternative fuels are described above in detail. The systems and methods are not limited to the specific embodiments described herein, but rather, components of the systems and / or steps of the methods can be used independently and separately from other components and / or steps described herein. For example, the methods can also be used in conjunction with other power generation systems and are not limited to practice with only the other power generation systems described herein. Rather, the exemplary embodiments can be implemented and used in conjunction with many other power generation applications.

[0067] Although specific features of various embodiments of the present disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the embodiments of the present disclosure, any feature of a drawing may be referenced and / or claimed in conjunction with any feature of any other drawing.

[0068] This written description uses examples to disclose embodiments of the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the embodiments of the present disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the embodiments described herein is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that are the same as the literal language of the claims, or if they include equivalent structural elements that are insubstantially different from the literal language of the claims.

Claims

1. A power generation system (100), comprising: a combustion system (108) configured to generate electricity by combusting only ethanol; a liquid supply system (104) configured to direct liquid ethanol to the combustion system (108); and a vapor supply system (106) configured to direct vaporous ethanol to the combustion system (108), wherein the combustion system (108) is ignited by combusting the liquid ethanol from the liquid supply system (104) and operates by combusting the vaporous ethanol from the vapor supply system (106); wherein, after igniting (604) the combustion system (108) with the liquid ethanol, the liquid supply system (104) is configured to reduce the volume of liquid ethanol supplied to the combustion system (108), and the vapor supply system (106) is configured to increase the volume of vaporized ethanol supplied to the combustion system (108) until the combustion system burns only vaporized ethanol.

2. The power generation system (100) of claim 1, wherein the combustion system (108) comprises a gas turbine engine (108).

3. The power generation system (100) of claim 2, wherein the gas turbine engine (108) includes a combustor section (206), the combustor section including a plurality of burners (214) and a plurality of fuel nozzles, the plurality of fuel nozzles being configured to atomize the liquid ethanol and inject the atomized liquid ethanol into the plurality of burners (214).

4. The power generation system (100) of claim 1, wherein the steam supply system (106) includes a burner (128) configured to vaporize liquid ethanol.

5. The power generation system (100) of claim 4, wherein the combustor (128) includes at least one heat exchanger (140).

6. The power generation system (100) of claim 5, wherein the combustor (128) further comprises a heat recovery steam generator (132) configured to receive exhaust gas from the combustion system (108), wherein the heat recovery steam generator (132) is configured to heat a heat exchange medium and direct the heat exchange medium from the heat recovery steam generator (132) to the at least one heat exchanger (140) to vaporize the liquid ethanol.

7. A method (600) of generating electricity using a power generation system (100), the power generation system (100) comprising a combustion system (108), a liquid supply system (104), and a steam supply system (106), wherein the steam supply system (106) comprises a heat recovery steam generator (132) and a burner (128), the method (600) comprising: directing (602) liquid ethanol from the liquid supply system (104) to the combustion system (108); igniting (604) the combustion system (108) by combusting the liquid ethanol using only the liquid ethanol from the liquid supply system (104) to generate electricity and exhaust gas; directing (606) the exhaust gas from the combustion system (108) to the heat recovery steam generator (132); heating (608) a heat exchange medium within the heat recovery steam generator (132) using the exhaust gas; directing (610) the heat exchange medium from the heat recovery steam generator (132) to the combustor (128); vaporizing (612) liquid ethanol using the heat exchange medium to produce vapor ethanol; directing (614) the vapor ethanol to the combustion system (108); and operating (616) the combustion system (108) by combusting the vaporous ethanol; wherein, after igniting (604) the combustion system (108) with the liquid ethanol, the liquid supply system (104) is configured to reduce the volume of liquid ethanol supplied to the combustion system (108), and the vapor supply system (106) is configured to increase the volume of vaporized ethanol supplied to the combustion system (108) until the combustion system burns only vaporized ethanol.

8. The method (600) of claim 7, wherein igniting (604) the combustion system (108) with the liquid ethanol from the liquid supply system (104) by combusting the liquid ethanol to generate electricity and exhaust gas comprises igniting (604) a gas turbine engine (108) with the liquid ethanol from the liquid supply system (104) by combusting the liquid ethanol to generate electricity and exhaust gas.

9. The method (600) of claim 8, wherein the gas turbine engine (108) includes a combustion section (206) comprising a plurality of burners (214) and a plurality of fuel nozzles, wherein the method (600) further comprises atomizing the liquid ethanol using the plurality of fuel nozzles.

10. The method (600) of claim 7, further comprising directing the vaporous ethanol to an inertial separator (134).

11. The method (600) of claim 10, wherein the inertial separator (134) comprises a centrifugal separator, wherein the method (600) further comprises separating liquid entrained in the vaporous ethanol using the inertial separator (134).

12. The method (600) of claim 7, further comprising preheating the steam supply system (106) using heat exchange medium from the heat recovery steam generator (132).

13. The method (600) of claim 8, wherein using the exhaust gas to heat a heat exchange medium within the heat recovery steam generator (132) comprises using the exhaust gas to heat steam within the heat recovery steam generator (132).

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