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Publication numberUS3359723 A
Publication typeGrant
Publication dateDec 26, 1967
Filing dateOct 29, 1965
Priority dateOct 29, 1965
Also published asDE1476765A1
Publication numberUS 3359723 A, US 3359723A, US-A-3359723, US3359723 A, US3359723A
InventorsGeorge R Bohensky, Walter A Herbst, Wesley D Niles, Charles W Siegmund
Original AssigneeExxon Research Engineering Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of combusting a residual fuel utilizing a two-stage air injection technique and an intermediate steam injection step
US 3359723 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

1967 G. R. BOHENSKY ETAL 3,359,723


COMPRESSOR EXHAUST WASTE HEAT BOILER AUXILIARY FUEL '4 amaa $22 322" WESLEY o.' NILES CHARLES w. SIEGMUND wpjm PATENT ATTORNEY United States. Patent METHOD OF COMBUSTING A RESIDUAL FUEL UTILIZING A 'TWO-STAGE AIR INJECTION TECHNIQUE AND AN INTERMEDIATE STEAM INJECTION STEP George R. Bohensky, Parsippany, Walter A. Herbst, Union, Wesley D. Niles, Roselle Park, and Charles W. Siegmund, Morris Plains, N.J., assignors to Esso Research and Engineering Company, a cor oration of Delaware Filed Oct. 29, 1965, Ser. No. 505,606 5 Claims. (Cl. 60-39.05)

ABSTRACT OF THE DISCLOSURE The present invention is concerned with a technique and apparatus for burning a high sulfur, high ash residual fuel which comprises adding about a stoichiometric amount of steam in an initial zone, thereafter adding steam passed about said initial zone to the combustion product in a secondary zone and thereafter adding addi tional air to said combustion products in a tertiary zone.

The present invention is broadly concerned with an improved gas turbine engine and with its method of operation. The invention is more particularly concerned with a gas turbine engine designed for utilizing a liquid petroleum fuel which is characterized by being a residual fuel containing a relatively high concentration of sulfur and ash forming constituents. In accordance with the present invention, a gas turbine engine is designed so as to be operated using a relatively low quantity of excess air upstream in the combustor and in combination with the addition of additional air downstream in the combustor, and also in combination with the use of steam. In accordance with one specific adaptation of the present invention, a controlled amount of steam injection is used to cool the combustor chamber walls and also the combustion products in the first twozones of a combustor while additional air is utilized in the final zone of the combustor. Thus, in accordance with the present invention, a gas turbine engine is operated by burning an ashcontaining fuel with essentially the stoichiometrically correct amount of air (0 to 3% excess) followed by quenching of the hot gases by steam or a mixture of steam and air added downstream from the primary combustion zone.

In the operation of a conventional, open cycle, gas turbine engine, it is necessary to utilize relatively large quantities of excess air with the combustion gases in order to keep the temperatures within the temperature limits which materials can withstand. For example, stoichiometric combustion of a typical fuel results in a temperature in the range of about 3400 F. to 4000 F. while the present limitation of the turbine blade materials in industrial gas turbine engines is in the range of about 1400 F. to 1600 F. For this reason, in conventional turbine engines as much as 500% excess air is used in order to lower the, temperatures to within a range which the materials can withstand. This results in inefiiciencies and other operating problems.

Also, for economic reasons it is desirable to utilize inexpensive petroleum fuels in turbine engines, particularly in stationary power plants. Such fuels include petroleum liquid fractions boiling above about 800 F. and having viscosities above about 400 SS at 150 F. These fuels contain a substantial amount of ash-forming components which include compounds of sodium, calcium, nickel, iron and vanadium. These fuels, in most instances, also have sulfur concentrations in the range from about 0.5


to 5% by weight. Thus, these fuels when used in gas turbine engines tend to be excessively corrosive and highly ash forming.

It is known that if near stoichiometric amounts of air, 0 to 3% excess air, are used in the combustion of residual fuels of this particular type containing vanadium and sodium salts, the corrosion and fouling characteristics associated with these fuels are substantially decreased. Therefore, for this reason it is much preferred to use a minium amount of excess air.

Such fuels, for example, when burned in the presence of large amounts of air (e.g. 5 to 500% above stoichiometric requirements) produced ash and products of combustion that form deposits and corrode the downstream hot parts of the engine (e.g. transition ducts, fixed nozzles, turbine blades). On the other hand, when the amount of air is limited to 0 to 3 wt. percent excess over the theoretically correct amount, the deposit-forming and corrosive compounds are not formed. These effects are illustrated by the following data obtained with a petroleum residual fuel containing 0.1 wt. percent ash.


0.007 wt. percent Na)] Amount of Combust. Air Ash Deposits, Corrosion Wt. Loss,

Percent Above Theoret. rug/em. mgJcnr-Ka) Reqmns.

(* Stainless steel 347 (18% chromium, 8% nickel).

However, stoichiometric combustion of a typical fuel results in a temperature in the range of about 3600 F. This is much too high for current turbine blade materials, which cannot practically handle gases hotter than about 1200 to 1800 F. Thus, means of cooling these combustion products to 1200 to 1800" F. must be employed. In current turbine engine design this is done by adding large amounts of excess air (up to 500% over stoichiometric requirements) to the combustor. This results in inefficiencies (because of the work required to compress this large amount of air) and gives the aforementioned harmful ash and combustion products.

In the method of operation disclosed herein this cooling is accomplished by steam an-d/ or steam and air added downstream from the primary combustion zone. The steam is produced in a waste heat boiler heated by the turbine exhaust and can be generated at pressures above the turbine cycle pressure. It can, therefore, be added directly to the cycle for cooling purposes and adds to the massv of the working fluid without requiring the compression work characteristic of air cooling. This results in increased power and thermal efliciency.

One form of a conventional gas turbine combustor comprises an exterior or outer shell and a substantially concentrically disposed inner shell or casing. The combustor has generally three main zones. Fuel is injected in the primary zone along with air where combustion occurs and where the temperature exceeds about .3000 F. Excess air is passed about the exterior of the casing walls of the primary zone to cool the walls of this primary zone. In the secondary zone of a conventional casing, the casing contains louvers, or slots, through which some of the excess air is admitted to within the casing which provides turbulence for complete combustion. The tertiary zone is essentially a quench zone where the major portion of the excess air is introduced to cool the combustion gases and provide the proper temperature for the fluid for utilization in the gas turbine cycle.

In accordance with the present invention, steam is utilized to cool the casing walls in the primary and secondary zones and thus permit the combustion to be carried out with about 3% excess air. In the tertiary zone where the combustion is essentially complete, in accordance with the present invention, the hot gases mixed with steam, are quenched by additional steam and/ or air which has bypassed the first two zones of the combustor basket or casing. One way of operating in this manner is by the use of a combustor comprising an outer shell, an inner shell or casing or combustor basket, and a third intermediate substantially concentrically disposed shell, the length of which is less than the length of the outer shell or casing. I

The unique combustor and method of operation will be readily understood by reference to the drawing illustrating one embodiment of the same. Referring specifically to the drawing, air is introduced into the compressor 10 by means of line 1. In accordance with the present invention, a stoichiometric portion of the compressed air at a pressure in the range from about 75 to 200 p.s.i., such as about 90 psi, is introduced into combustor 20 by means of line 2. Combustor 20 comprises an outer shell 30, an inner shell or casing 40, and an intermediate shell 50. Thus, an annular area 31 is provided between shells 30 and 50, and an annular area 32 between shells 40 and 50. The stoichiometric portion of the air is introduced into primary zone 1 within casing 40 of combustor 20. Fuel is also introduced into primary zone I of casing 40 by means of line 3. Conventional means are utilized to secure the combustion of the fuel within casing 40. As mentioned, the amount of air introduced into primary zone I is below excess air, preferably in the range of from stoichiometric to 3% excess air.

In accordance with the present invention, steam, preferably produced as hereinafter described, is introduced into an annular area 32 about primary zone I by means of line 4. This steam flows through annular area 32 and serves to cool the walls of primary zone I. Substantially complete combustion occurs in primary zone I within casing 40. The hot combustion gases flow into secondary zone II of casing 4-0 wherein the hot gases are mixed with the steam which flows into secondary zone II through slots or louvers 5, which provide communication from area 32 to within casing 40.

In accordance with the present invention, a portion of the compressed air from compressor is introduced into annular area 31 of combustor 20 which is positioned about annular area 32. This compressed air flows through annular area 31 and is introduced by means of apertures or slots 6 into tertiary zone III of casing 40 wherein the same is mixed with the combustion gases and the steam. This added air serves as a quench for the steam and the combustion products. The combustor products are withdrawn from combustion zone 20 by means of line 7 and function to drive turbine 80 in a conventional manner. Turbine 80 is linked by suitable means 8 in order to drive compressor 10. The load 60 is driven by suitable means 9 from turbine S0.

The spent turbine gases are withdrawn from turbine 80 by means of line 11 and passed into waste heat boiler 70 wherein they are utilized to generate steam which is withdrawn by means of line 4 and passed into annular area 32. Suflicient water is introduced into waste heat boiler 70 by means of line 12 while spent exhaust gases are withdrawn from waste heat boiler 70 by means of line 13.

The advantage of the present invention is that it is possible to burn residual fuel without the attendant corrosion problems presently limiting turbine applications with this type of fuel. As residual fuel is considerably less expensive, the technique permitting its use represents a sizeable savings in economics. An added advantage of this cycle is the increase in efficiency obtained by injecting steam and increasing output work by increasing mass flow without increasing the compressor load.

As pointed out heretofore, the amount of air mixed with the fuel in primary zone I is substantially stoichiornetric and preferably should not exceed about 3% excess air.

The amount of steam introduced into secondary zone II is in the range from about 3 to 20 pounds of steam per pound of fuel, preferably about 6 to 10 pounds of steam per pound of fuel to the primary combustion zone. The pressure of this steam is in the range of 75 to 200 p.s.i. The amount of air introduced into tertiary zone III of casing 40 is from 0 to 50 lbs. per lb. of fuel to the combustor preferably 2535 lbs. per lb. of fuel. Under these conditions the temperature of the gases withdrawn from casing 40 and utilized in turbine 50 is in the range from about 1350 to 1700 F. and the pressure is in the range from 75 to 200 p.s.i. Under some conditions the recoverable heat in the exhaust gases may not be sufficient to provide all the steam required in this process. Additional steam may be generated in an oil-fired boiler which may be separate from, or a part of, the waste heat boiler 70. This auxiliary fuel will be supplied through line 14 at a rate equivalent to 0 to 1 lb. of auxiliary fuel per pound of primary fuel burned in the turbine combustor. Also as pointed out heretofore, the present turbine engine and technque is particularly adapted for the combusting of heavy residual fuels which contain in the range from about 50 to 1500 as, for example, 1000 parts per million of ash and wherein the vanadium content is greater than 2 as, for example, in the range from about 60 to 1000 parts per million of fuel.

Thus the basic concept of the present invention is to burn a fuel containing harmful trace components (i.e. metals and sulfur) with stoichiometric amouns of air. This keeps the combustion products of the metals and sulfur in a low valence state where they do not form the harmful deposits characteristic of the higher valence states obtained with large amounts of excess air. The products from the stoichiometric combustion, however, are too hot to be used directly in a turbine and therefore must be cooled. If air is used as a quench at high temperatures, the ash and sulfur will be oxidized and the benefits of the stoichiometric combustion will be lost. This is avoided by quenching first with steam and then adding air if necessary. The amount of steam required is that necessary to reduce the temperature of the combustion products to a point where they will not oxidize in the presence of added air.

In order to further illustrate the present invention Attachr nent I shows the relative amounts of steam and air required for 1500 F. turbine inlet temperature under one set of turbine conditions. The various cases are as follows:

Case 1.Conventional turbine operation where cooling is done by the use of excess air over that required for combustion. The combustion air and coolant air are supplied by the compressor.

Case 2.-Steam from waste heat boiler replaces part of the air for cooling. The amount of steam is held at 10% of mass cycle flow. The additional cooling required to reach 1500 F. turbine inlet temperature is accomplished by air from the turbine compressor.

Case 3.Steam from waste heat boiler is added to cycle for cooling. Total air flow held same as in Case 1. Fuel flow is increased as allowed by increased cooling from added steam.

Case 4.-The maximum amount of steam that can be produced from the waste exhaust heat is added to cycle. Fuel flow is same as Case 1. Air flow decreased since steam provides part of cooling.

Case 5.Maximum amount of waste heat steam added to cycle. The same as Case 4, except total air flow held c stant s. same as Case 1 and fuel flow increased.

Case 6.-flteam alone is used for cooling. Fuel flow same as Case 1. Coolant air eliminated. This case requires more steam than is available from Waste heat in exhaust i.e. supplemental fuel oil must be fired under steam boiler.

Case 7.--Liquid water and maximum waste heat steam used for cooling. Coolant air eliminated. Fuel flow same as Case 1.

The desirable cases are 2, 3, 4 and 5 in which the amounts of steam used are limited to that produceable from the waste heat in the exhaust gases. While it would be difficult to justify the production of additional steam specifically for this purpose, under certain conditions waste steam may be available from outside sources which is illustrated in Case 6.

zone, and thereafter driving a turbine with the gaseous mixture.

2. Process as defined by claim 1 wherein said air added to said tertiary zone is passed about the steam added to said secondary zone.

3. Process as defined by claim 1 wherein the amount of steam added to said secondary zone is in the range of 6.0 to 10 pounds of steam per pound of fuel introduced into said primary zone.

4. Process as defined by claim 1 wherein a stoichiometric amount of air is introduced into said primary zone.

5. Process as 'denfied by claim 1 wherein additional steam is supplied to said secondary zone by burning supplemental fuel oil in a waste heat boiler at a quantity to 0.7 pound of supplemental fuel per pound of fuel to the combustor.

ATTACHMENT I.TURBINE OPERATION WITH ADDED STEAM lBases: Turbine press. ratio 9.7; turbine inlet temp. 1,500 F.; Compression discharge temp. 650 F.; turbine exhaust temp. 1,000

F.; waste heat boiler exhaust 400 F.; adiabatic flame temp. 4,000 FJ Case 1 2 3 4 5 6 7 All Air Air+10% Air+10% Air-l-Max. Air+Max. All Water+Max. Conven- Steam Steam Waste Heat Waste Heat Steam Waste Heat tional Steam Steam Steam Fuel Flow, Lbs 1 1 1. 7 1 2.0 1 1 Combustion Air, Lbs 14. 7 14. 7 24. 4 14. 7 29. 4 14. 7 14. 7 Cooling Air, Lbs 67 37 58 25 53 0 0 Total Air, Lbs 82 52 82 40 82 15 Steam, Lbs.:

From waste heat boiler 0 6 11 10 21 13 5 From fuel fired boiler 0 0 0 0 0 8 0 Auxiliary Fuel Oil Required, Lbs 0 0 0 0 0 0,5 0 Liquid Water 0 0 0 0 0 0 5 To combustor.

What is claimed is:

1. Improved process for the operation of a gas turbine engine which comprises introducing a residual fuel boiling above about 50 F. and having an ash content to 1500 parts per million of fuel, a vanadium content of 2 to 400 parts per million of fuel, and a sulfur concentration in the range from about 0.5 to 5% by weight, and less than about 5% excess air into a primary zone of a combustor and combusting the same to produce combustion products, passing about 3 to pounds of steam per pound of fuel about said primary zone and mixing said combustion products with said steam in a secondary zone, then adding about to pounds of additional air per pound of fuel to said combustion products and said steam in a tertiary References Cited UNITED STATES PATENTS CARLTON R. CROYLE, Primary Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1988456 *Mar 19, 1931Jan 22, 1935Milo AbGas turbine system
US2636345 *Mar 19, 1948Apr 28, 1953Babcock & Wilcox CoGas turbine combustor having helically directed openings to admit steam and secondary air
US2660032 *Oct 4, 1947Nov 24, 1953Rosenthal HenryGas turbine cycle employing secondary fuel as a coolant
US2678531 *Feb 21, 1951May 18, 1954Chemical Foundation IncGas turbine process with addition of steam
US2781635 *Apr 26, 1952Feb 19, 1957Freeport Sulphur CoProcess and heating system for providing hot water and power for sulfur mining
US3038308 *Jul 16, 1956Jun 12, 1962Nancy W N FullerGas turbine combustion chamber and method
US3238719 *Mar 19, 1963Mar 8, 1966Harslem Eric WLiquid cooled gas turbine engine
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3657879 *Jan 26, 1970Apr 25, 1972Walter J EwbankGas-steam engine
US3747336 *Mar 29, 1972Jul 24, 1973Gen ElectricSteam injection system for a gas turbine
US3756029 *Aug 3, 1971Sep 4, 1973Sulzer AgGas/steam turbine plant and a method of operating same
US3785146 *May 1, 1972Jan 15, 1974Gen ElectricSelf compensating flow divider for a gas turbine steam injection system
US3921389 *Oct 3, 1973Nov 25, 1975Mitsubishi Heavy Ind LtdMethod and apparatus for combustion with the addition of water
US4519769 *Nov 15, 1983May 28, 1985Akio TanakaApparatus and method for the combustion of water-in-oil emulsion fuels
US4823546 *Apr 13, 1988Apr 25, 1989International Power TechnologySteam-injected free-turbine-type gas turbine
US4893467 *Jul 13, 1988Jan 16, 1990Gas Research InstituteControl system for use with steam injected gas turbine
US4899537 *Feb 7, 1984Feb 13, 1990International Power Technology, Inc.Steam-injected free-turbine-type gas turbine
US4958488 *Apr 17, 1989Sep 25, 1990General Motors CorporationCombustion system
US4969324 *Jul 24, 1989Nov 13, 1990Gas Research InstituteControl method for use with steam injected gas turbine
US5265410 *Mar 29, 1991Nov 30, 1993Mitsubishi Jukogyo Kabushiki KaishaPower generation system
US5285628 *Jan 18, 1990Feb 15, 1994Donlee Technologies, Inc.Method of combustion and combustion apparatus to minimize Nox and CO emissions from a gas turbine
US5461854 *Jul 7, 1993Oct 31, 1995Griffin, Jr.; Arthur T.Combustor cooling for gas turbine engines
US5694761 *Oct 31, 1995Dec 9, 1997Griffin, Jr.; Arthur T.Combustor cooling for gas turbine engines
US6116018 *Mar 5, 1998Sep 12, 2000Mitsubishi Heavy Industries, Ltd.Gas turbine plant with combustor cooling system
US6176075Dec 2, 1997Jan 23, 2001Arthur T. Griffin, Jr.Combustor cooling for gas turbine engines
US6341485 *May 5, 2000Jan 29, 2002Siemens AktiengesellschaftGas turbine combustion chamber with impact cooling
US6389814Dec 20, 2000May 21, 2002Clean Energy Systems, Inc.Hydrocarbon combustion power generation system with CO2 sequestration
US6523349Jun 19, 2001Feb 25, 2003Clean Energy Systems, Inc.Clean air engines for transportation and other power applications
US6568187 *Dec 10, 2001May 27, 2003Power Systems Mfg, LlcEffusion cooled transition duct
US6598398May 21, 2002Jul 29, 2003Clean Energy Systems, Inc.Hydrocarbon combustion power generation system with CO2 sequestration
US6622470May 14, 2001Sep 23, 2003Clean Energy Systems, Inc.Semi-closed brayton cycle gas turbine power systems
US6637183May 14, 2001Oct 28, 2003Clean Energy Systems, Inc.Semi-closed brayton cycle gas turbine power systems
US6715294 *Jan 23, 2002Apr 6, 2004Drs Power Technology, Inc.Combined open cycle system for thermal energy conversion
US6824710May 14, 2001Nov 30, 2004Clean Energy Systems, Inc.Working fluid compositions for use in semi-closed brayton cycle gas turbine power systems
US6868677May 24, 2002Mar 22, 2005Clean Energy Systems, Inc.Combined fuel cell and fuel combustion power generation systems
US6910335Aug 22, 2003Jun 28, 2005Clean Energy Systems, Inc.Semi-closed Brayton cycle gas turbine power systems
US6945029Nov 17, 2003Sep 20, 2005Clean Energy Systems, Inc.Low pollution power generation system with ion transfer membrane air separation
US7021063Mar 10, 2004Apr 4, 2006Clean Energy Systems, Inc.Reheat heat exchanger power generation systems
US7043920Jul 8, 2003May 16, 2006Clean Energy Systems, Inc.Hydrocarbon combustion power generation system with CO2 sequestration
US7882692Apr 30, 2007Feb 8, 2011Clean Energy Systems, Inc.Zero emissions closed rankine cycle power system
US8813473 *Aug 17, 2012Aug 26, 2014Rolls-Royce PlcSteam injected gas turbine engine
US20100154430 *Dec 22, 2008Jun 24, 2010Krishan Lal LuthraSystem and method for operating a gas turbine using vanadium-containing fuels
US20130055698 *Mar 7, 2013Rolls-Royce PlcSteam injected gas turbine engine
USRE43252Sep 22, 2003Mar 20, 2012Vast Power Portfolio, LlcHigh efficiency low pollution hybrid Brayton cycle combustor
CN104302893A *Jan 29, 2013Jan 21, 2015鲍尔法斯有限责任公司Gas turbine energy storage and energy supplementing systems and methods of making and using the same
EP0795685A1 *Feb 13, 1997Sep 17, 1997Asea Brown Boveri AgMulti-staged gas-turbine with steam cooling and feeding into the combustor
EP2199569A1 *Dec 15, 2009Jun 23, 2010General Electric CompanySystem and method for operating a gas turbine using vanadium-containing fuels
EP2565417A2 *Aug 17, 2012Mar 6, 2013Rolls-Royce plcSteam injected gas turbine engine
WO1997014881A1 *Oct 20, 1995Apr 24, 1997Arthur T Griffin JrCombustor cooling for gas turbine engines
WO2013116185A1 *Jan 29, 2013Aug 8, 2013Kraft Robert JGas turbine energy storage and energy supplementing systems and methods of making and using the same
WO2014066276A2 *Oct 21, 2013May 1, 2014Kraft Robert JGas turbine energy supplementing systems and heating systems, and methods of making and using the same
U.S. Classification60/775, 60/39.55
International ClassificationF02C7/16, F01K21/04, F02C3/30
Cooperative ClassificationF02C3/30, F02C7/16, F01K21/047, F05D2260/2322
European ClassificationF02C7/16, F02C3/30, F01K21/04E