CA2715973A1

CA2715973A1 - System, method and apparatus for lean combustion with plasma from an electrical arc

Info

Publication number: CA2715973A1
Application number: CA2715973A
Authority: CA
Inventors: Todd Foret
Original assignee: Foret Plasma Labs LLC
Current assignee: Foret Plasma Labs LLC
Priority date: 2008-02-12
Filing date: 2009-02-12
Publication date: 2009-08-20
Anticipated expiration: 2029-02-12
Also published as: WO2009102907A3; WO2009102907A2; AU2009214660A1; AU2009214660B2; EP2255081A2; US20150000251A1; MX2010008819A; US8833054B2; EP2255081B1; US20120036829A1; US9163584B2; US20140260179A1; US9869277B2; US8074439B2; CA2715973C; US20090235637A1; EP2255081A4

Abstract

The present invention provides a plasma arc torch that can be used for lean combustion. The plasma arc torch includes a cylindrical vessel, an electrode housing connected to the first end of the cylindrical vessel such that a first electrode is (a) aligned with a longitudinal axis of the cylindrical vessel, (b) extends into the cylindrical vessel, and (c) can be moved along the longitudinal axis, a linear actuator connected to the first electrode to adjust a position of the first electrode, a hollow electrode nozzle connected to the second end of the cylindrical vessel such that the center line of the hollow electrode nozzle is aligned with the longitudinal axis of the cylindrical vessel, and wherein the tangential inlet and the tangential outlet create a vortex within the cylindrical vessel, and the first electrode and the hollow electrode nozzle crate a plasma the discharges through the hollow electrode nozzle.

Description

SYSTEM, METHOD AND APPARATUS FOR LEAN COMBUSTION
WITH PLASMA FROM AN ELECTRICAL ARC

FIELD OF THE INVENTION

The present invention relates generally to gas turbine engines. More specifically, the present invention relates to a supersonic lean combustion plasma steam reforming turbine engine that will combust low BTU gas such as landfill gas, biogas, blast furnace gas, coke oven gas and syngas.

BACKGROUND OF THE INVENTION

There are many problems associated with lean fuel combustion or low BTU gas combustion in gas turbine engines. With the successful flight of the X-43A, hypersonic flight has achieved several technological goals and entered a new era. With further developments, it will reach Technology Readiness Level. However, FAA and EPA emission regulations in addition to the cost of fossil-based aviation fuels have pushed the aviation community into research and development for highly efficient aircraft engines that work on alternative and/or renewable fuels.
In particular, the land based gas turbine community has been conducting research for integrating coal gasification with a combined cycle turbine ("IGCC"). In any case, the combustion of the product from gasification of carbon containing matter - synthesis gas ("syngas") - requires major modifications to current gas turbine engines. Because syngas has a low heating value ("LHV") compared to natural gas, significantly more fuel must be injected in an IGCC turbine than a natural gas turbine. Therefore, the mass-flow-and thus the output power-of the gas turbine is much higher for an IGCC application. For the same reason, the gas turbine's output power is flat-rated to very high temperatures.

Supersonic Combustion and Flame Holding Problem 1: Gas Turbine to Ramjet or Scramjet Operations High Bypass Fan Gas Turbines are the primary engines for transportation aircraft. Typical speeds are 893km/h (482kt) at altitude on aircraft such as the Boeing 777-300.
Military aircraft use augmentors ("afterburners") to achieve and sustain supersonic flight. Only the new F-22 raptor can sustain supersonic flight without the use of an augmentor. Air breathing ramjets or scramjets are required to achieve hypersonic flight using air. However, only one successful Scramjet has been flown since the beginning of aviation. The major problem with ramjets and scramjets can be traced back to the early problem of flame holding or preventing engine flame out. In addition, no matter which configuration is chosen for Hypersonic Flight a problem remains - transition from subsonic to supersonic and finally hypersonic flight will require several different engines.

Problem 2: Lean Combustion or Low BTU Fuel Combustion Fuel-lean combustion can increase efficiency while lowering emissions.
However, current combustors cannot hold a flame during lean combustion conditions. Likewise, low BTU fuel such as syngas is difficult to combust in current gas turbine engines.

Ansaldo Energia (Genoa, Italy) has engineered a new gas turbine V94.2K2 that targets the low-Btu (3.5 MJ/Kg - 7 MJ/Kg LHV) market. The K2 gas turbine builds on the design philosophy of Ansaldo Energia's V94.2K that can handle fuels with 8 MJ/Kg -13 MJ/Kg LHV. The K2 is intended for Chinese and Eastern European markets where the company sees a demand for power generation from industrial gases, such as Blast Furnace Gas (BFG) and Coke Oven Gas (COG).

The Lower Explosive Limit (LEL) and Upper Explosive Limit (UEL) for common hydrocarbon based fuels, such as diesel(0.6% to 7.5%), gasoline(1.4% to 7.6%), and natural gas(Methane -5.0% to 15%) is fairly limited in range. On the otherhand, syngas a product of natural gas(methane) steam reforming or gasification of hydrocarbons, coal, biomass, etc. is composed of hydrogen and carbon monoxide. The LEL and UEL for hydrogen(4% to 75%) and carbon monoxide(12.5% to 74.0%) are much broader than the parent fuel such as methane. Thus, this allows syngas (hydrogen + carbon monoxide) to be burned in a lean mode. The problem with syngas is that it is not widely available. It must be generated onsite by steam reforming natural gas or gasification of carbonaceous matter such as hydrocarbons or biomass.
Typical gasifiers are very large and extremely expensive. However, a small and inexpensive plasma gasifier, such as the ArcWhirl , US Patent #7,422,695 issued on Sept. 9, 2008 to the present inventor coupled to an IC engine could achieve both lean burn and supersonic combustion by gasifying the fuel first then combusting it in a cyclone combustor that is driven by a turbocharger.

Problem 3: Match lit in Hurricane Supersonic combustion has been compared to keeping a match lit in a hurricane or tornado. All gas turbines slow the flow of compressed air to below supersonic velocities in order to maintain a flame. This is due to the inherit design of the flame-holding capabilities of the combustor for a given turbine.

2 Move match to eye of Hurricane It is well known that speeds within a cyclone can easily attain supersonic velocities. For example, turbochargers and centrifugal compressors easily attain speeds of over 100,000 RPM.
Likewise, the air circulating within a turbocharger would far exceed supersonic speeds. Thus, the present invention achieves supersonic combustion by utilizing the centripetal forces within a rotating air column, such as a cyclone or hurricane for energy transfer, while utilizing the void, commonly referred to as the eye or vortex, in order to keep the match lit in order to maintain ignition. Simply put, the match is moved from the whirling column of air known as the shear wall to the eye or center of the hurricane.

Problem 4: Flame is stretched due to Whirl Flow & melts turbine Placing the igniter within the center of the combustor is common for many types of gas turbine engines. Allison's C-18 to C-20 series of gas turbine engines utilize a front mounted axial flow compressor that sweeps the compressed air to the combustor via externally mounted air conduits.
If the combustor were redesigned such that the air tubes entered tangentially to the combustor housing, thus creating centrifugal flow within the redesigned cyclone or vortex combustor, then the igniter and fuel nozzle would be placed within the central void space or eye of a whirling mass of air. However, this would create a detrimental effect on the compressor turbine if operated at supersonic combustion utilizing an intense igniter such as a plasma torch. The intense heat within the centrally stretched out plasma flame would melt the center of the compressor turbine.

Problem 5: Flame Out It is well known that lean combustion can achieve high efficiency while producing low emissions. However, attempting to achieve lean combustion within current internal combustion("IC") engine designs may lead to low reaction rates, flame extinction ("Flame Out"), instabilities, and mild heat release. Likewise, many IC engines are very sensitivity to fuel/air mixing.

With the current push for sequestering carbon or utilizing renewable fuels, a need exists for a relatively inexpensive turbine engine design that can operate in a lean fuel combustion mode in addition to a supersonic combustion mode. If such a turbine could be easily coupled to a motor generator, high bypass fan or propeller, this would allow for rapid transition to renewable fuels for electrical generation, aviation, marine propulsion and thermal oxidation.
The ability to transition from subsonic to supersonic then to hypersonic flight with the same engine would

3 solve many problems with reaching space at an affordable payload rate. The ability to use the same air breathing supersonic combustion turbine as a steam plasma thruster in space solves the issues of carrying a large oxidizer payload.

SUMMARY OF THE INVENTION

The present invention provides a supersonic lean fuel combustion plasma arc turbine that includes a plasma arc torch, a cyclone combustor and a turbocharger. The plasma arc torch includes a cylindrical vessel having a first end and a second end, a tangential inlet connected to or proximate to the first end, a tangential outlet connected to or proximate to the second end, an electrode housing connected to the first end of the cylindrical vessel such that a first electrode is (a) aligned with a longitudinal axis of the cylindrical vessel, (b) extends into the cylindrical vessel, and (c) can be moved along the longitudinal axis, a linear actuator connected to the first electrode to adjust a position of the first electrode within the cylindrical vessel along the longitudinal axis of the cylindrical vessel, a hollow electrode nozzle connected to the second end of the cylindrical vessel such that the center line of the hollow electrode nozzle is aligned with the longitudinal axis of the cylindrical vessel, and wherein the tangential inlet and the tangential outlet create a vortex within the cylindrical vessel, and the first electrode and the hollow electrode nozzle crate a plasma the discharges through the hollow electrode nozzle. The cyclone combustor is connected to a hollow electrode nozzle of the plasma arc torch.
The cyclone combustor has a tangential entry, a tangential exit, and an exhaust outlet.
The turbocharger has a turbine connected to a compressor via a shaft. The turbine entry is connected to the tangential exit of the cyclone combustor, and a compressor exit is connected to the tangential entry of the cyclone combustor.

In addition, the present invention provides a plasma turbine thermal oxidizer that includes a plasma arc torch, a vessel housing at least one ceramic cyclone, a first turbocharger and a second turbocharger. The plasma arc torch includes a cylindrical vessel having a first end and a second end, a tangential inlet connected to or proximate to the first end, a tangential outlet connected to or proximate to the second end, an electrode housing connected to the first end of the cylindrical vessel such that a first electrode is (a) aligned with a longitudinal axis of the cylindrical vessel, (b) extends into the cylindrical vessel, and (c) can be moved along the longitudinal axis, a linear actuator connected to the first electrode to adjust a position of the first electrode within the cylindrical vessel along the longitudinal axis of the cylindrical vessel, a hollow electrode nozzle connected to the second end of the cylindrical vessel such that the center line of the hollow

4 electrode nozzle is aligned with the longitudinal axis of the cylindrical vessel, and wherein the tangential inlet and the tangential outlet create a vortex within the cylindrical vessel, and the first electrode and the hollow electrode nozzle crate a plasma the discharges through the hollow electrode nozzle. The vessel housing at least one ceramic cyclone is connected to the hollow electrode nozzle. The first turbocharger is connected to a first recuperator, wherein the first recuperator is attached to the tangential input of the plasma arc torch. The second turbocharger is connected to a second recuperator, wherein the second recuperator is attached to an air intake of the vessel housing the ceramic cyclone(s). The discharge exhaust of the vessel housing the ceramic cyclone(s) is attached to a turbine of each turbocharger.

The present invention also provides a plasma turbine air breathing and steam rocket that includes a plasma arc torch, a vessel housing at least one ceramic cyclone, a recuperator encapsulating an exhaust nozzle connected to a discharge exhaust to the vessel housing the ceramic cyclone(s), a first turbocompressor for compressing air, oxidant, or steam connected to the recouperator, a second turbocompressor for pressuring fuel connected to the tangential input of the plasma arc torch, a valve system and a secondary oxidant injection system. The plasma arc torch includes a cylindrical vessel having a first end and a second end, a tangential inlet connected to or proximate to the first end, a tangential outlet connected to or proximate to the second end, an electrode housing connected to the first end of the cylindrical vessel such that a first electrode is (a) aligned with a longitudinal axis of the cylindrical vessel, (b) extends into the cylindrical vessel, and (c) can be moved along the longitudinal axis, a linear actuator connected to the first electrode to adjust a position of the first electrode within the cylindrical vessel along the longitudinal axis of the cylindrical vessel, a hollow electrode nozzle connected to the second end of the cylindrical vessel such that the center line of the hollow electrode nozzle is aligned with the longitudinal axis of the cylindrical vessel, and wherein the tangential inlet and the tangential outlet create a vortex within the cylindrical vessel, and the first electrode and the hollow electrode nozzle crate a plasma the discharges through the hollow electrode nozzle. The vessel housing at least one ceramic cyclone is connected to the hollow electrode nozzle. The valve system connects the tangential output of the plasma arc torch to the recouperator that converts the first turbocompressor into a vapor compressor pulling a suction on the recuperator while a water pump injects water into the recuperator and the compressed steam cools the ceramic cyclone and enters into the cyclone and shifts the syngas to hydrogen and carbon dioxide while injecting a secondary oxidant into the nozzle, thus allowing the rocket to transition from air breathing to steam propulsiona water pump, The ceramic cyclone is cooled with a preheated

5 combustion air from the first turbocompressor which cooled the exhaust nozzle in the recuperator, an exhaust is scavenged to drive the first and second turbocompressors and a valve system means.

Moreover, the present invention provides a method for supersonic lean fuel combustion by creating an electric arc, generating a whirl flow to confine a plasma from the electric arc, generating a combustion air whirl flow, extracting a rotational energy from one or more hot gases, recuperating energy from the hot gases, and utilizing the electrical arc for converting fuel to syngas while confining the plasma to the vortex of the whirling combustion air in order to maintain and hold a flame for supersonic combustion while coupled to a means for extracting rotational energy from the hot lean combustion exhaust gas while recuperating energy for preheating the fuel and combustion air.

The present invention is described in detail below with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS

The above and further advantages of the invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which:

FIGURE 1 is a diagram of a plasma arc torch in accordance with one embodiment of the present invention;

FIGURE 2 is a diagram of a Supersonic Lean Combustion Plasma Turbine in accordance with one embodiment of the present invention;

FIGURE 3 is a diagram of a Supersonic Lean Combustion Plasma Turbine Motor Generator in accordance with another embodiment of the present invention;

FIGURE 4 is a diagram of a Supersonic Lean Combustion Plasma Turbine High Bypass Fan in accordance with another embodiment of the present invention;

FIGURE 5 is a diagram of a Supersonic Lean Combustion Plasma Turbine Propeller in accordance with another embodiment of the present invention;

FIGURE 6 is a diagram of a Plasma Turbine Thermal Oxidizer in accordance with another embodiment of the present invention;

FIGURE 7 is a diagram of a Plasma Turbine Air Breathing & Steam Rocket with Recuperator in accordance with another embodiment of the present invention;
and

6

7 PCT/US2009/033979 DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.

Now referring to FIGURE 1, a plasma arc torch 100 in accordance with one embodiment of the present invention is shown. The plasma arc torch 100 is a modified version of the ARCWHIRL device disclosed in U.S. Patent No. 7,422,695 (which is hereby incorporated by reference in its entirety) that produces unexpected results. More specifically, by attaching a discharge volute 102 to the bottom of the vessel 104, closing off the vortex finder, replacing the bottom electrode with a hollow electrode nozzle 106, an electrical arc can be maintained while discharging plasma 108 through the hollow electrode nozzle 106 regardless of how much gas (e.g., air), fluid (e.g., water) or steam 110 is injected into plasma arc torch 100. In addition, when a valve (not shown) is connected to the discharge volute 102, the mass flow of plasma 108 discharged from the hollow electrode nozzle 106 can be controlled by throttling the valve (not shown) while adjusting the position of the first electrode 112 using the linear actuator 114.

As a result, plasma arc torch 100 includes a cylindrical vessel 104 having a first end 116 and a second end 118. A tangential inlet 120 is connected to or proximate to the first end 116 and a tangential outlet 102 (discharge volute) is connected to or proximate to the second end 118. An electrode housing 122 is connected to the first end 116 of the cylindrical vessel 104 such that a first electrode 112 is aligned with the longitudinal axis 124 of the cylindrical vessel 104, extends into the cylindrical vessel 104, and can be moved along the longitudinal axis 124. Moreover, a linear actuator 114 is connected to the first electrode 112 to adjust the position of the first electrode 112 within the cylindrical vessel 104 along the longitudinal axis of the cylindrical vessel 124 as indicated by arrows 126. The hollow electrode nozzle 106 is connected to the second end 118 of the cylindrical vessel 104 such that the center line of the hollow electrode nozzle 106 is aligned with the longitudinal axis 124 of the cylindrical vessel 104. The shape of the hollow portion 128 of the hollow electrode nozzle 106 can be cylindrical or conical.
Moreover, the hollow electrode nozzle 106 can extend to the second end 118 of the cylindrical vessel 104 or extend into the cylindrical vessel 104 as shown. As shown in FIGURE 1, the tangential inlet 120 is volute attached to the first end 116 of the cylindrical vessel 104, the tangential outlet 102 is a volute attached to the second end 118 of the cylindrical vessel 104, the electrode housing 122 is connected to the inlet volute 120, and the hollow electrode nozzle 106 (cylindrical configuration) is connected to the discharge volute 102. Note that the plasma arc torch 100 is not shown to scale.

A power supply 130 is electrically connected to the plasma arc torch 100 such that the first electrode 112 serves as the cathode and the hollow electrode nozzle 106 serves as the anode.
The voltage, power and type of the power supply 130 is dependant upon the size, configuration and function of the plasma arc torch 100. A gas (e.g., air), fluid (e.g., water) or steam 110 is introduced into the tangential inlet 120 to form a vortex 132 within the cylindrical vessel 104 and exit through the tangential outlet 102 as discharge 134. The vortex 132 confines the plasma 108 within in the vessel 104 by the inertia (inertial confinement as opposed to magnetic confinement) caused by the angular momentum of the vortex, whirling, cyclonic or swirling flow of the gas (e.g., air), fluid (e.g., water) or steam 110 around the interior of the cylindrical vessel 104. During startup, the linear actuator 114 moves the first electrode 112 into contact with the hollow electrode nozzle 106 and then draws the first electrode 112 back to create an electrical arc which forms the plasma 108 that is discharged through the hollow electrode nozzle 106. During operation, the linear actuator 114 can adjust the position of the first electrode 112 to change the plasma 108 discharge or account for extended use of the first electrode 112.

Referring now to FIGURE 2, a diagram of a Supersonic Lean Combustion Plasma Turbine 200 in accordance with one embodiment of the present invention is shown. In order to gasify, crack, reform or pyrolyize fuel, the fuel 202 may be introduced into the system at one or more points:
(a) introducing the fuel 202a into the plasma 108 directly through first electrode 112 wherein the first electrode 112 is hollow; (b) mixing (e.g., via an eductor) the fuel 202b with the gas (e.g., air), fluid (e.g., water) or steam 110 introduced into the tangential inlet 120 of the plasma arc torch 100; and (c) introducing (e.g., via an eductor) the fuel 202c into the plasma 108 plume exiting the hollow electrode nozzle 106. The plasma arch torch 100 is connected to a cyclone combustor 204 with a tangential entry 206 and tangential exit 208. The cyclone combustor 204 is connected to a turbocharger 210 via valve 212. Hot gases enter into a turbine 214 of the turbocharger 210. The turbine 214 rotates a compressor 216 by means of a shaft with a pinion 218. A compressor inlet valve 220 is connected to the compressor 216.
Compressor inlet valve 220 eliminates the need for stators to impart a whirl flow to match the compressor wheel rotation direction. In addition, by utilizing a tapered reducer for the housing the velocity of the air 222 must increase in order to conserve angular momentum. By utilizing a plunger style stopper

8 valve assembly 224 coupled to a linear actuator 226, the mass flow can be pinched or reduced while maintaining velocity. The physical separation of the compressor/turbine or turbocharger 210 from the combustor 204 allows for a radically different design for gas turbines, power plants and airframes. The turbocharger 210 can be located and oriented to maximize airflow while minimizing foreign object damage (FOD). In addition, the turbocharger 210 may be coupled to rotating unions and tubing in order to rotate or direct the exhaust from the turbine 214 for thrust vectoring. In order to maximize efficiency a first stage recuperator 228 is placed on the discharge exhaust from the turbine 214 and a second stage recuperator 230 is place on the discharge exhaust from the combustor 204 via a valve 232. Compressed air 234 enters into the first stage recuperator 228 and then into the second stage recuperator 230.
The hot compressed air 236 then enters into the combustor 204 via a volute with tangential entry 206.

More specifically, the compressor inlet valve 220 includes a volute with a tangential entry, a cone-shaped reducer connected to the volute, a linear actuator connected to the volute, and a cone-shaped stopper disposed within the cone-shaped reducer and operably connected to the linear actuator. A controller is connected to the linear actuator to adjust a gap between the cone-shaped stopper and the cone-shaped reducer to increase or decrease mass flow while maintaining whirl velocity to closely match compressor tip velocity.

Although there are several variations and modes of operations a few brief examples will be given in order to quickly demonstrate the uniqueness as well as functionality of the Supersonic Lean Combustion Plasma Turbine 200. A vortex is formed within the plasma arc torch 100 using water, steam, fuel or any other fluid 110. The arc is struck and a plasma is discharged into the eye of the cyclone combustor 204. The plasma syngas plume entering into the cyclone combustor 204 is also the igniter. Since it is in the eye of the cyclone it will be extended along the longitudinal axis of the combustor 204 and into valve 232. By throttling valves 212 and 232 the turbine can be operated from a takeoff mode and transition to supersonic and hypersonic flight. The purpose of the pinion 218 on the turbocharger 210 in combination with separating the combustor 204 from the compressor 216 and turbine 214 allows for a unique and completely unobvious mode of operation.

Referring now to FIGURE 3, a diagram of a Supersonic Lean Combustion Plasma Turbine Motor Generator 300 in accordance with another embodiment of the present invention is shown.
Two or more Plasma Turbines 200 (200a and 200b as shown) are coupled to a bull gear 302 in a locked-train fashion. The bull gear 302 drives a motor generator 306 via drive shaft 304. This

9 configuration allows for operating in a very fuel efficient and cost effective means. The first Plasma Turbine 200a is started by using the motor to rotate the pinions in order to rotate the compressor. The cyclone valve's stopper is opened to allow air into the compressor. The second Plasma Turbine's 200b stopper is placed in a closed position in order to unload the compressor. This can also be accomplished by placing electrical clutches on the pinion. When air flow enters into the combustor, the plasma arc torch 100 is ignited with only water or steam flowing through it in the same rotational direction as the cyclone combustor.
Once the plasma arc is stabilized fuel is flowed into the plasma arc torch 100 and gasified and synthesized into hydrogen and carbon monoxide. The hot syngas plasma flows into the cyclone combustor. It is ignited and lean combusted and flowed out of the combustor via the tangential exit. Valve is fully opened while valve is shut in order to maximize flow into the turbine.
Valves and are then adjusted according to torque loading on the pinion in addition to turbine and compressor speed.
By operating only one combustor at its maximum efficiency the generator can be operated as a spinning reserve. All utility companies within the US are required to maintain "Spinning Reserves." In order to come up to full power additional Plasma Turbines can be started almost instantly with very little lag time. This annular Plasma Turbine configuration may have multiple bull gears on a single shaft with each bull gear consisting of multiple Plasma Turbines.

Now referring to FIGURE 4, a diagram of a Supersonic Lean Combustion Plasma Turbine High Bypass Fan 400 in accordance with another embodiment of the present invention is shown. Two or more Plasma Turbines 200 (200a and 200b as shown) are coupled to a bull gear 302 in a locked-train fashion. A high bypass fan 402 is attached to the shaft 304.
Likewise, a small motor generator may be attached to the opposite end of the shaft for starting and inflight electrical needs. Once again the Plasma Turbine configuration allows for maximizing fuel efficiency while idling at the gate and taxing by operating only one Plasma Turbine attached to the bull gear. Prior to takeoff all Plasma Turbines are brought online to maximize thrust. After takeoff Plasma Turbines may be taken offline to maximize fuel efficiency during climbout and at cruise altitude and speed.

When the pilot is ready to transition to supersonic flight the turbine inlet valve is slowly closed while the combustor valve is opened. The high bypass fan may be feathered in order to reduce speed of the bull gear or to reduce drag. Likewise an inlet cowling may be used to close air flow to the high bypass fan. Air flow into the combustor is directly due to speed of the aircraft. This is accomplished with an additional three way valve (not shown) connected to the combustor tangential entry. Thus, the combination of the plasma arc torch 100 and the cyclone combustor coupled to a unique exhaust valve allows for a true plasma turbine scramjet that can be operated in a supersonic lean fuel combustion mode.

Referring to FIGURE 5, a diagram of a Supersonic Lean Combustion Plasma Turbine Propeller in accordance with another embodiment of the present invention is shown, which is similar to the motor generator and high bypass fan, the system allows for a very unique marine turbine. In comparison, the US Navy's Spruance class destroyers were one of the first class of Naval ships to utilize high powered marinized aircraft turbines. Two GE LM-2500 Gas Turbine Engines were coupled to the port shaft via a bull gear and two GE LM-2500 Gas Turbine Engines were coupled to the starboard shaft via a bull gear. This gave the ship a total of 100,000 shaft horsepower. In order to operate in the most fuel efficient mode, only one engine was operated while the other engine was decoupled from the bull gear via a friction and spur gear type clutch.
The other shaft was placed in a trail mode position and allowed to spin or rotate freely. If full power was needed the other 3 gas turbine engines required about 3 minutes to start in an emergency mode.

There were two major problems associated with the LM-2500 coupled to a bull gear. First, when starting from a dead in the water position, the engineers had to conduct a dead shaft pickup. This required engaging the clutch and placing the friction brake on which held the power turbine. The turbine was started and hot gases flowed across a non-moving power turbine section. The brake was released and the power turbine rotated thus turning the bull gear. The variable pitched propeller was usually placed at zero pitch.

Returning back to FIGURE 5, the bull gear 302 with multiple Plasma Turbines 200 (200a and 200b are shown) may be attached to a drive shaft 304 that is connected to a propeller 502.
However, this system can be greatly augmented with a motor generator (not shown) directly attached to the drive shaft 304. In fact, the propeller 502 can be eliminated and replaced with an all electric drive pod. Thus, FIGURE 3 would be installed and simply would provide electrical power to the electric drive pod. Neither rotating a shaft for transportation and propulsion purposes nor rotating a large motor generator may be required from the Plasma Turbine System.
Now referring to FIGURE 6, a diagram of Plasma Turbine Thermal Oxidizer 600 in accordance with another embodiment of the present invention is shown. The plasma arc torch 100 is attached to a commonly available filter vessel which houses a ceramic hydrocylone. Ceramic hydrocyclones are available from CoorsTek and Natco.

Many landfills as well as wastewater treatment plants produce a low BTU fuel referred to as biogas. Likewise, many industries produce a very low BTU offgas that must be thermally oxidized or incinerated. The plasma turbine thermal oxidizer achieves lean combustion by first gasifying the low BTU fuel in another low BTU fuel - syngas. However, since the syngas has a larger ignition range (LEL to UEL) it can be combusted at high flow rates without additional fuel.

The system is operated in the following mode. The plasma arc torch 100 is turned on to establish an arc. Water or steam may be flowed in the plasma arc torch 100 to form the whirl or vortex flow. Air is flowed into a compressor through a recuperator and into the vessel. The air surrounds and cools the ceramic cyclone. The air enters into the ceramic hydrocyclone tangentially then exits as a hot gas into the turbines. Once air flow is established the low BTU
gas is flowed into a compressor then into a recuperator. The hot low BTU gas is flowed into the plasma arc torch 100 where it is steam reformed into syngas. Once again, the syngas plasma enters into apex valve of the ceramic cyclone. The syngas is lean combusted and traverses to the turbine, recuperator and then exhausted for additional uses. In this system, the turbochargers may be installed with high speed alternators for providing electricity to operate the power supplies for the plasma arc torch 100.

This system is especially useful at wastewater treatment plants ("WWTP5").
Biogas is often produced from digesters. Likewise, all WWTPs use air to aerate wastewater.
Since the Plasma Turbine Thermal Oxidizer operates in a lean fuel combustion mode, there is ample oxygen left within the exhaust gas. This gas can be used for aerating wastewater.
Likewise, plasma arc torch 100 can be used to disinfect water while steam reforming biogas. In addition, biosolids can be gasified with the plasma arc torch 100 to eliminate disposal problems and costs.

Referring now to FIGURE 7, a diagram of a Plasma Turbine Air Breathing & Steam Rocket with Recuperator 700 in accordance with another embodiment of the present invention is shown.
The thermal oxidizer 600 of FIGURE 6 can easily be converted into a rocket or process heater.
A nozzle and recuperator are attached to the outlet of the combustor. Air or an oxidant are flowed into the recuperator. The hot air or oxidant exits the recuperator and enters into the vessel and into the ceramic cyclone. Fuel is pressurized via a compressor and enters into the plasma arc torch 100 where it is converted or cracked into syngas. The syngas plasma plume ejecting into the ceramic cyclone is controlled via a multi-position fuel recirculation valve. A
portion of the fuel may flow into the nozzle to increase thrust. In order to drive the turbines a portion of the hot exhaust gas is scavenged and flowed to the inlets of the fuel turbocompressor and turbocharger. When used as an air breathing rocket, upon reaching altitudes where lean combustion cannot be sustained due a lack of oxygen molecules, in lieu of carrying an oxidant, the rocket would carry water. The water in pumped into the recuperator to generate steam. The turbocharger is valved such that it can pull a vacuum on the recuperator. The turbocharger is then operated as a vapor compressor. The compressed steam is flowed in the vessel. The extremely hot syngas reacts with the steam in the cyclone for conversion to hydrogen and carbon dioxide via the water gas shift reaction. Since the water gas shift reaction is exothermic this will ensure that the steam remains in the vapor state. A small amount of liquid oxidizer may be added to combust the hydrogen.

Finally, the present invention provides a method for supersonic lean fuel combustion by creating an electric arc, generating a whirl flow to confine a plasma from the electric arc, generating a combustion air whirl flow, extracting a rotational energy from one or more hot gases, recuperating energy from the hot gases, and utilizing the electrical arc for converting fuel to syngas while confining the plasma to the vortex of the whirling combustion air in order to maintain and hold a flame for supersonic combustion while coupled to a means for extracting rotational energy from the hot lean combustion exhaust gas while recuperating energy for preheating the fuel and combustion air.

The foregoing description of the apparatus and methods of the invention in preferred and alternative embodiments and variations, and the foregoing examples of processes for which the invention may be beneficially used, are intended to be illustrative and not for purpose of limitation. The invention is susceptible to still further variations and alternative embodiments within the full scope of the invention, recited in the following claims.

Claims

1. A supersonic lean fuel combustion plasma arc turbine comprising:
a plasma arc torch comprising:
a cylindrical vessel having a first end and a second end, a tangential inlet connected to or proximate to the first end, a tangential outlet connected to or proximate to the second end, an electrode housing connected to the first end of the cylindrical vessel such that a first electrode is (a) aligned with a longitudinal axis of the cylindrical vessel, (b) extends into the cylindrical vessel, and (c) can be moved along the longitudinal axis, a linear actuator connected to the first electrode to adjust a position of the first electrode within the cylindrical vessel along the longitudinal axis of the cylindrical vessel, a hollow electrode nozzle connected to the second end of the cylindrical vessel such that the center line of the hollow electrode nozzle is aligned with the longitudinal axis of the cylindrical vessel, and wherein the tangential inlet and the tangential outlet create a vortex within the cylindrical vessel, and the first electrode and the hollow electrode nozzle crate a plasma the discharges through the hollow electrode nozzle;
a cyclone combustor connected to the hollow electrode nozzle of the plasma arc torch, wherein the cyclone combustor has a tangential entry, a tangential exit, and an exhaust outlet;
and a turbocharger having a turbine connected to a compressor via a shaft, wherein an turbine entry is connected to the tangential exit of the cyclone combustor, a compressor exit is connected to the tangential entry of the cyclone combustor.

2. The supersonic lean fuel combustion plasma arc turbine as recited in claim 1, further comprising a first valve disposed between the tangential exit of the cyclone combustor and a the turbine entry.

3. The supersonic lean fuel combustion plasma arc turbine as recited in claim 1, further comprising compressor inlet valve connected to a compressor entry of the compressor.

4. The supersonic lean fuel combustion plasma arc turbine as recited in claim 3, wherein the compressor inlet valve comprises:
a volute with a tangential entry;
a cone-shaped reducer connected to the volute;
a linear actuator connected to the volute, a cone-shaped stopper disposed within the cone-shaped reducer and operably connected to the linear actuator; and a controller for connected to the linear actuator to adjust a gap between the cone-shaped stopper and the cone-shaped reducer to increase or decrease mass flow while maintaining whirl velocity to closely match compressor tip velocity.

5. The supersonic lean fuel combustion plasma arc turbine as recited in claim 1, further comprising:
a first stage recuperator connected to a discharge exhaust of the turbine;
a second stage recuperator connected to a discharge exhaust of the cyclone combuster;
and wherein the compressor exit is connected to the first stage recuperator such that a compressed air from the compressor is heated by the first stage recuperator and the second stage recuperator and enters the combustor via the tangential entry of the combustor.

6. The supersonic lean fuel combustion plasma arc turbine as recited in claim 5, further comprising a second valve disposed between the discharge exhaust of the cyclone combustor and the second stage recuperator.

7. The supersonic lean fuel combustion plasma arc turbine as recited in claim 1, further comprising a pinon gear attached to the shaft between the turbine and the compressor.

8. The supersonic lean fuel combustion plasma arc turbine as recited in claim 7, further comprising a bull gear and a drive shaft connected to the pinion gear.

9. The supersonic lean fuel combustion plasma arc turbine as recited in claim 8, further comprising a motor generator connected to the drive shaft.

10. The supersonic lean fuel combustion plasma arc turbine as recited in claim 8, further comprising a high bypass fan connected to the drive shaft.

11. The supersonic lean fuel combustion plasma arc turbine as recited in claim 8, further comprising a propeller connected to the drive shaft.

12. A plasma turbine thermal oxidizer comprising:
a plasma arc torch comprising:
a cylindrical vessel having a first end and a second end, a tangential inlet connected to or proximate to the first end, a tangential outlet connected to or proximate to the second end, an electrode housing connected to the first end of the cylindrical vessel such that a first electrode is (a) aligned with a longitudinal axis of the cylindrical vessel, (b) extends into the cylindrical vessel, and (c) can be moved along the longitudinal axis, a linear actuator connected to the first electrode to adjust a position of the first electrode within the cylindrical vessel along the longitudinal axis of the cylindrical vessel, a hollow electrode nozzle connected to the second end of the cylindrical vessel such that the center line of the hollow electrode nozzle is aligned with the longitudinal axis of the cylindrical vessel, and wherein the tangential inlet and the tangential outlet create a vortex within the cylindrical vessel, and the first electrode and the hollow electrode nozzle crate a plasma the discharges through the hollow electrode nozzle;
a vessel housing at least one ceramic cyclone connected to the hollow electrode nozzle;
a first turbocharger connected to a first recuperator, wherein the first recuperator is attached to the tangential input of the plasma arc torch;
a second turbocharger connected to a second recuperator, wherein the second recuperator is attached to an air intake of the vessel housing the ceramic cyclone(s); and wherein a discharge exhaust of the vessel housing the ceramic cyclone(s) is attached to a turbine of each turbocharger.

13. A plasma turbine air breathing and steam rocket comprising:
a plasma arc torch comprising:
a cylindrical vessel having a first end and a second end, a tangential inlet connected to or proximate to the first end, a tangential outlet connected to or proximate to the second end, an electrode housing connected to the first end of the cylindrical vessel such that a first electrode is (a) aligned with a longitudinal axis of the cylindrical vessel, (b) extends into the cylindrical vessel, and (c) can be moved along the longitudinal axis, a linear actuator connected to the first electrode to adjust a position of the first electrode within the cylindrical vessel along the longitudinal axis of the cylindrical vessel, a hollow electrode nozzle connected to the second end of the cylindrical vessel such that the center line of the hollow electrode nozzle is aligned with the longitudinal axis of the cylindrical vessel, and wherein the tangential inlet and the tangential outlet create a vortex within the cylindrical vessel, and the first electrode and the hollow electrode nozzle crate a plasma the discharges through the hollow electrode nozzle;
a vessel housing at least one ceramic cyclone connected to the hollow electrode nozzle;
a recuperator encapsulating an exhaust nozzle connected to a discharge exhaust to the vessel housing the ceramic cyclone(s);
a first turbocompressor for compressing air, oxidant, or steam connected to the recouperator;
a second turbocompressor for pressuring fuel connected to the tangential input of the plasma arc torch;
a valve system connecting the tangential output of the plasma arc torch to the recouperator that converts the first turbocompressor into a vapor compressor pulling a suction on the recuperator while a water pump injects water into the recuperator and the compressed steam cools the ceramic cyclone and enters into the cyclone and shifts the syngas to hydrogen and carbon dioxide while injecting a secondary oxidant into the nozzle, thus allowing the rocket to transition from air breathing to steam propulsiona water pump;
a secondary oxidant injection system; and wherein the ceramic cyclone is cooled with a preheated combustion air from the first turbocompressor which cooled the exhaust nozzle in the recuperator, an exhaust is scavenged to drive the first and second turbocompressors and a valve system means.

14. A method for supersonic lean fuel combustion comprising the steps of:
creating an electric arc;
generating a whirl flow to confine a plasma from the electric arc;
generating a combustion air whirl flow;

extracting a rotational energy from one or more hot gases;
recuperating energy from the hot gases; and utilizing the electrical arc for converting fuel to syngas while confining the plasma to the vortex of the whirling combustion air in order to maintain and hold a flame for supersonic combustion while coupled to a means for extracting rotational energy from the hot lean combustion exhaust gas while recuperating energy for preheating the fuel and combustion air.