US3002345A

US3002345A - Apparatus for minimizing the deposition of deleterious compounds in a petroleum fuel fired gas chamber

Info

Publication number: US3002345A
Application number: US2019A
Authority: US
Inventors: William E Young
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1960-01-12
Filing date: 1960-01-12
Publication date: 1961-10-03
Anticipated expiration: 1978-10-03
Also published as: GB926366A

Description

3,002,345 G THE DEPOSITION OF DELETER IOUS Oct. 3, 1961 w. E. YOUNG APPARATUS FOR MINIMIZIN COMPOUNDS IN' A PETROLEUM FUEL FIRED GAS CHAMBER Filed Jan. 12, 1960 IN TEGRATING CONTROLLER FIG].

TO THER l/l O COUPLE FUEL CONTROL FIG.4.

INVENTOR WILLIAM E.YOUNG nited States This invention relates to gas turbine power plants generally, more particularly to gas turbine power plants operating on residual petroleum oil as a fuel and has for an object to provide an improved method and apparatus for inhibiting the formation of deleterious deposits formed by the combustion gas products on the metallic components of the turbine.

Residual fuel oil is becoming more widely used in the operation of industrial gas turbines because of its low cost and high B.t.u. content. However, as well known in the art, residualpetroleum fuel oil contains sodium, sulphur and vanadium which form compounds during combustion of the fuel and can cause serious corrosion of the metal components of the gas turbine and associated structure. The vanadium cannot be removed economically from the fuel oil, at the present time, nor are there commercial alloys or coatings which can be employed on the hot engine parts exposed thereto, to reliably resist its attack at elevated temperatures. Accordingly, at the present time various solutions to the problem have been proposed, all of which lie in the introduction of certain metals or metallic compounds into the fuel and air systems for the power plant which, during combustion, tend to combine chemically or physically with the vanadium, thus rendering it innocuous to the gas turbine components.

One of the preferred metal elements employed as an additive is magnesium or its compounds. These materials may be introduced in various forms such as metallic magnesium, magnesium oxide, magnesium hydroxide, magnesium sulphate, carbonate of magnesium or even as an organic compound of magnesium. These materials I have heretofore been added directly to the fuel as aqueous solutions but, when so added, tend to deposit in the fuel lines. Oil slurries of these materials have also been used but have induced severe erosion and plugging of the fuel pumps and fuel injection nozzles. To obviate these difliculties, these materials, in comminuted form, have been added to combustion air in boiler installations utilizing residual fuel oil. However, this is not easily done with gas turbines.

Although these materials are effective in inhibiting the formation of the harmful vanadates, they do have one serious disadvantage. They tend to be deposit forming and rapidly build up a thick coating on the turbine blades, causing the blades to lose their optimum airfoil shape and causing the machine to operate at lower efiiciency, often times within a few hours of steady operation.

It has been found that when a second material such asaluminum or one of its compounds is employed as an additive and fed concomitantly with magnesium materials into the plant, the combination of the aluminum and magnesium materials tends to prevent or at least minimize the accumulation of deposits on the turbine blades and I at other hotcomponents. Accordingly, it is an object of the inveniton to provide two materials as additives for residual oil fuel fired gas turbine power plants, wherein one of the materials serves to inhibit the formation of harmful vanadium, sodium and sulphur compounds, and the other material iseffective to. minimize the accumulation or deposition of these compounds on the turbine components.

It has further been found, that in order to be eifective, the proportions of the two materials must be relatively Patented ot. 3, i951 closely held and, further, the quantity of the materials fed must be varied with fuel pressure and/or fuel flow of the specific fuel employed, temperature within the power plant, speed of the rotor and other variables. Accordingly, it is a further object of the invention to provide apparatus for feeding two materials of the above type concomitantly into the fuel combustion chamber of a gas turbine power plant in preselected proportions and at a rate varying directly with plant operating variables.

Ordinarly, when a material such as magnesium or its compounds is used alone, a 3/1 atom ratio of magnesium to vanadium has been found sufiicient. However, when a second material such as aluminum or its compounds is employed in conjunction With the magnesium materials, a 6/ 3/ 1 atom ratio of magnesium and aluminum to vanadium, respectively, appears to be essential. Although the mechanism by which the aluminum is rendered effective to complement the effects of the magnesium has not been definitely established, it appears that the aluminum material diverts some of the magnesium by forming a magnesium aluminate therewith, so that more magnesium must be added to be available to combine with the vanadium. However, this aluminate has a higher melting temperature and seems to be much less adherent to the blade components than the usual compounds of magnesium such as the vanadates and sulphates.

It appears that the vanadates, chiefly sodium pyrovanadate and sodium orthovanadate formed in the residual oil fuel ash is deposited on the blades in molten and high viscous form and acts as a flux, removing the protective oxides from the blades and destroying their corrosion resistance, as well as providing oxygent for continuing corrosion.

The magnesium material, when employed alone, will substantially minimize the above phenomenon by forming a protective coating about the blades. However, this coating builds up during operation of the machine, as mentioned above, until the efficiency of the power plant drops to economically unendurable values. In accordance with the invention, the aluminum permits the magnesium to act in the same manner but is highly effective to control the thickness, of the coating formed by the magnesium to a reasonable value.

In accordance with the invention, to insure that the magnesium and aluminum materials are fed in proper quantities to suit all operating conditions of the power plant, the two materials are combined in a composite rod, such as a tube made of one material and filled with the other material, and fed by a suitable variable speed mechanism directly into the fuel combustion chamber of the gas turbine power plant. The composite rod may be stored on a reel and fed by suitable sheaves driven by a variable speed driving mechanism, the speed of which is controlled by an integrating controller responsive to engine operating variables such as fuel pressure, turbine inlet temperature, etc. Accordingly, with increasing fuel pressure, indicative of increasing fuel flow to the combustor, the variable speed driving mechanism is effective through its controller to feed the composite rod into the fuel combustor at an increasing rate. Conversely, when the fuel pressure is lowered, the composite rod is fed into the combustor at a lower rate. In a similar manner, the speed of the composite rod may be increased or decreased in accordance with increase or decrease, respec-- tively, of the temperature adjacent the turbine inlet.

If tubing is used, the tubular sheath may be formed of aluminum and filled with one of the magnesium compounds such as magnesium oxide, the proper proportions of magnesium oxide to aluminum being arrived at by forming the sheath of the required wall thickness and diameter.

On the other hand, various modifications of this at rangement may be employed, to dispense with the sheath, by forming a composite rod or strip of magnesium and aluminum bonded to each other to form a bimetallic structure, or the rod may be formed of any suitable magnesium and aluminum alloys; It may" also be feasible to form the composite rod of comminuted magnesium and aluminum materials bonded together by a suitable plastic binder.

Although magnesium and aluminum materials have been heretofore mentioned for clarity and simplicity, the magnesium materials may be substituted by other elements of the same chemical group, as follows: beryllium, calcium, barium, strontium, and zinc. On the other hand, the aluminum materials may be substituted by other elements having the same chemical characteristics, such as: chromium, iron, manganese, silicon, boron, ti tanium, zirconium, molybdenum, and tungsten.

The foregoing and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application; in which:

FIG. 1 is a schematic view illustrating a typical industrial gas turbine power plant having the invention incorporated therein;

FIG. 2 is a transverse section of the tubular structure taken on line IIII of FIG. 1; and

FIGS. 3, 4 and 5 are sections similar to FIG. 2 but illustrating different modifications of the invention.

Referring to the drawing in detail, in FIG. 1 there is shown a typical gas turbine power plant incorporating a compressor section 11 having a bladed rotor 12, a gas turbine section 13 including a bladed rotor 14 drivingly connected to the compressor rotor 12 by a shaft 15 and having interposed therebetween fuel combustion apparatus 16. The power plant 10 is provided with housing structure 17 enclosing the above recited components and having an opening 13 through which a drive shaft 19 is extended for providing shaft power to an external load (not shown). As well known in the art, the shaft 19 is connected to the

rotor aggregate

12, 14 and 15 and driven thereby.

The combustion apparatus 16 includes an annular array of apertured fuel combustion chambers 21 disposed within a plenum chamber 22 formed in the housing structure 17 and communicating with the outlet 23 of the compressor. Since the fuel combustion chambers 21 may be identical, only one has been shown and will be described.

The fuel combustion chamber 21 is of cannister form and is provided at its upstream end wall portion with a fuel injection nozzle 25 to which fuel is fed from a suitable fuel supply 26 containing residual fuel oil through a conduit 27, by a fuel pump ZS-and regulated by a suitable fuel control 29. The fuel control may be regulated as required to vary the fuel flow rate to an annular fuel manifold 30 connected to the nozzles 25- by branch conduits 31.

The turbine section 13 is further provided with an inlet 33 communicating with the fuel combustion chambers 21 and an outlet 34 communicating with an exhaust outlet conduit 35.

As thus far described, the power plant 10 is substantially conventional and operates in substantially the following manner. As residual fuel oil from the fuel supply 26 is delivered, as required, by the fuel control 2% to the fuel combustion chambers 21 through the fuel injecting nozzles 25 and ignited by suitable means (not shown), air is induced through an air intake 36 by the compressor 11 and pressurized, and thence delivered through the compressor outlet 23 into the plenum chamber 22. The thus pressurized air enters the fuel combustion chambers 21, where it combines with the atomized fuel oil being admitted thereto by the fuel nozzles 25 to sustain combustion. The resulting hot gaseous products of combustion are directed through the downstream ends of the fuel combustion chambers-21 and through the turbine inlet 33 tothe turbine section 13-, thereby motivating the turbine rotor 14. The turbine rotor 14 rotates the shaft 15 and compressor rotor 12. The thus expanded motive gases are exhausted through the turbine outlet 34 and thence through the exhaust outlet conduit 35,. as indicated by the arrows,. to any region. of lower pressure, such as atmospheric.

In accordance with the invention, the housing 1.7' isprovided with a generally frusto-conical combustion. section housing portion 37 having a plurality of. apertures 38 formed therein communicating with apertures 39 (only one shown) formed in each of the fuel: combustion chambers 21. As shown in FIG. 1, a composite rod such as a tubular sheathed structure 40 is fed through the apertures 38 and 39 into the fuel combustion zone 41 within the fuel combustion chamber 21.

The tubular structure 40' may be formedin' long continuous lengths, stored upon a rotatably mounted reel 42 and having its free endportion passing through a pair of rollers or

sheaves

43 and 44. The sheave 44 is rotatably connected to the drive shaft 45 of variable speed drive mechanism 46 rotatable in the direction indicated by the arrow to feed the tubular sheath structure 4% into'the fuel combustion chamber 21.

The speed of the variable speed drive mechanism 46 is controlled by a suitable integrating controller 47, responsive to fuel pressure from the fuel control 29, admitted thereto by a conduit 48, and to the temperature of the turbine inlet 33 as sensed by a thermocouple 49 disposed at the downstream end of the combustion chamber 21 and connected to the controller 47.

Referring to FIG. 2, the tubular sheath structure 40 comprises a metallic sheath 51 within which is disposed a compacted comminuted metallic material or compound 52. The sheath 4'0 and the material 52 disposed therewithin may be formed of any two of the materials selected from eachof the following two groups:

Group I Aluminum Boron Chromium Titanium" Iron Zirconium Manganese Molybdenum Silicon Tungsten Group II Magnesium Barium Beryllium Strontium. Calcium Zinc It will be understood thatthe sheath: 51 is preferably formed of the selected metal while the material 52 disposed within the sheath may be formed by comminuting the selected metal or employing. the oxide, sulphate, carbonate, chloride or hydroxideof the metal.

When the materials selected from groups I and II are aluminum and magnesium, a 6/3/1 atom ratio of magnesium, aluminum and vanadium. has been found to be adequate. Accordingly, to fulfill these requirements, aluminum tubing having an outside diameter of inch, 4 inch or inch, with acorresponding Wall thickness of .011 inch, .021 inch. and .032 inch, could be employed, for example.

A representative 5000 kw. gas turbine power plant, having six fuel combustion chambers 21, operating atfull load and utilizing 833 lbs. per combustion chamber per hour of a residual fuel oil having 400- p.p .m. vanadium, would require about .529 lb. per hour of aluminum and 1.569 lbs. per hour of magnesium oxide for: each combustion chamber. The optimum linear feed rate for a A; inch tube would be about 24 inches per minute per fuel combustion chamber or a total of 144' inches of tubing per minute. On the other hand, if inch tubing were employed, about 2.65 inches per minute per combustion chamber or a total of 1519 inches per minute would be required. Similar calculations could be made for other types of materials employed.

In FIG. 3 there is shown a composite rod 53 formed of alloys of materials selected from groups I and II and formed into a solid mass, thereby dispensing with the need for providing a sheath and filling the same with comminuted material.

In FIG. 4, another variation is shown wherein the materials selected from the two groups above may be bonded to each other to form a composite rod in the form of a bimetallic strip 54 having one portion 55 formed of one material and the other portion 56 of the other material.

In FIG. 5, a further embodiment is shown wherein a composite rod 57 is formed of comminuted materials selected from groups I and II in proper proportion and bonded to each other by a suitable binding agent, such as one of the plastic resins.

During operation, as fuel is admitted into the combustion chamber 21 by the fuel injecting nozzle 25, the sheath structure 40 is fed thereinto by the variable speed drive mechanism 46 at a rate determined by the fuel pressure in the fuel control 29 and the temperature of the gases at the turbine inlet 33 and integrated in the integrating controller 47 which has been preset for a range corresponding to the vanadium content of the fuel. Accordingly, since the rate of feed of the sheath structure 40 is thus regulated, the proper amount of additive for any variable condition of operation of the power plant is thus insured.

Although the integrated controller 47 has been illustrated and described as being controlled by fuel pressure and turbine inlet temperature, it is within the scope of the invention to control this controller in response to other engine operating variables such as r.p.m. of the shaft 19, compressor pressure, etc.

As the sheath structure 40 is fed into the fuel combustion chamber 21, it is consumed in the fuel combustion process and modifies the hot products of combustion formed in such a manner that the usual and deleterious compounds of vanadium, sodium, and sulphur are inhibited. The magnesium is thus rendered effective to provide a protective coating about the blading and associated components of the turbine section 13, thereby minimizing the corrosive effectiveness of the hot motive gases of combustion. Concomitantly therewith, the aluminum is combined with some of the magnesium to form magnesium aluminate. This aluminate is efiective to control the accumulation thickness of the protective coating formed by the magnesium to the minimum thickness required to prevent corrosive attack by the hot products of combustion and preventing excessive buildup or formation of this protective coating, thereby enabling the turbine section to operate at substantially high aerodynamic efiiciency.

It will now be seen that, with the invention, clogging or erosion of the fuel system components by the admis sion of additives thereto is obviated. Also, the mixing in special tanks of slurries for feeding the additives directly to the residual fuel oil is obviated. In addition thereto, the rate at which the additives are injected is positively controlled, as required for optimum plant operation, and is automatically modified continuously a required. Since the additives are admitted directly into the fuel combustion chamber, settling, sludging, agglomeration and pre-reaction with the fuel in the fuel conduits is obviated.

Although the feeding apparatus for providing the additive materials has been shown in conjunction with only one fuel combusion chamber 21, it will be understood that if a plurality of such combustion chambers are employed, the remaining fuel combustion chambers may be fed by similar apparatus through their associated apertures 38. Although each may be provided with separate controllers and engine variable sensing means, if desired,

6 all of the feeding apparatus may be controlled by one set of engine operating sensing devices.

While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

What is claimed is:

l. Agas turbine power plant comprising an air compressor, a fuel combustion chamber and a gas turbine driven by the gaseous products of combustion formed in said chamber, said gas turbine having metal components subject to corrosion attack by compounds of vanadium, sodium and sulphur, means for injecting a petroleum fuel containing one or more of the above compound forming elements into said combustion chamber for combustion purposes, a coil of composite rod containinga-t least two materials in preselected proportions, one of said materials being effective to inhibit the formation of at least one of the above compounds and forming another compound and the other of said amterials being effective to minimize the deposition of said another compound on said turbine components, means for feeding said rod directly into said combustion chamber, and means for controlling said feeding means in accordance with an operating condition of said power plant.

2. A gas turbine power plant comprising an air compressor, a fuel combusion chamber and a gas turbine driven by the gaseous products of combustion formed in said chamber, said gas turbine having metal components subject to corrosion attack by compounds of vanadium, means for injecting a petroleum fuel containing vanadium into said combustion chamber for combustion purposes, a coil of tubing containing at least two materials in preselected proportions, one of said materials being effective to inhibit the formation of said vanadium compounds and forming another compound and the other of said materials being effective to minimize the deposition of said another compound on said turbine components, a variable speed drive mechanism for feeding said tubing directly into said combustion chamber at a variable rate, and means for controlling said variable speed drive mechanism in accordance with a variable operating condition of said power plant, said one material forming said tubing and said other material being comminuted and contained in said tubing.

3. A gas turbine power plant comprising an air compressor, a fuel combustion chamber and a gas turbine driven by the gaseous products of combustion formed in said chamber, said gas turbine having metal components subject to corrosion attack by compounds of vanadium, sodium and sulphur, means for injecting a petroleum fuel containing one or more of the above compound forming elements into said combustion chamber for combustion purposes, a coil of composite rod containing at least two materials in preselected proportions, one of said materials being eifective to inhibit the formation of at least one of the above compounds and forming another compound and the other of said materials being effective to minimize the deposition of said another compound on said turbine components, means including a variable speed drive mechanism and sheave structure for feeding said rod directly into said combustion chamber at a variable rate, and a controller for controlling said variable speed drive mechanism in accordance with a variable operating condition of said power plant.

4. A gas turbine power plant comprising an air compressor, a fuel combustion chamber and a gas turbine driven by the gaseous products of combustion formed in said chamber, said gas turbine having metal blading elements subject to corrosion attack by compounds of vanadium, sodium and sulphur, means including a fuel control for controlling the rate of injection of a petroleum fuel containing vanadium, and sodium or sulphur into said combustion chamber for combustion, a coil of composite rod containing magnesium and aluminum in preselected proportions, and means for feeding said rod into said combustion chamber at a rate sufficient to minimize formation of said compounds on said gas turbine blading.

5. A gas turbine power plant comprising an air compressor, a fuel combustion chamber and a gas turbine driven by the gaseous products of combustion formed in said chamber, said gas turbine having metal blades and associated components subject to corrosion attack by compounds of vanadium, means including a ,fuel control for controlling the rate of injection. of a petroleum fuel containing vanadium into said combustion chamber for combustion, a coil of tubular sheathing containing magnesium and aluminum, and variable speed mechanism for feeding said tubular sheathing into said combustion chamber for consumption at a rate sufficient to inhibit formation of said vanadium compounds and minimize accumulation of deposits on said gas turbine blades and components, said sheathing being formed of said aluminum and said magnesium being comminuted and disposed in said sheathing.

6. A gas turbine power plant comprising an air compressor, a full combustion chamber and a gas turbine driven by the gaseous products of combustion formed in said chamber, said gas turbine having metal components subject to corrosion attack by compounds of vanadium, sodium and sulphur, mean including a fuel control for controlling the rate of injection of a petroleum fuel containing vanadium, and sodium or sulphur into said combustion chamber for combustion, a composite rod containing two materials in preselected proportions, one of said materials being selected from the group comprising aluminum, chromium, iron, manganese, silicon, boron, titanium, zirconium, molybdenum and tungsten, and the other of said materials being selected from the group comprising magnesium, beryllium, calcium, barium, strontium and zinc, and means for feeding said rod into said combustion chamber for consumption at a rate sulficient to inhibit formation of said compounds and minimize accumulation of deposits on said gas turbine components.

7. A gas turbine power plant comprising an air compressor, a fuel combustion chamber and a gas turbine driven by the hot gaseous products of combustion formed in said combustion chamber; said power plant having metal components subject to corrosion attack by com- 8 pounds of vanadium, a supply of petroleum fuel containing vanadium, means including a fuel control for controlling the rate of injection of said fuel into said combustion chamber for combustion, a coil of tubular sheathed structure including a metallic tubular sheath having a comminuted material disposed therein, said sheathed structure being consumable in said combustion chamber to inhibit formation of said vanadium compounds and minimize accumulation of deposits on said metal components, means including a variable speed drive mechanism for feeding said sheathed structure into said combustion chamber at a variable rate, and an integrating controller responsive to at least one power plant operating characteristic for controlling the speed of said variable speed drive mechanism.v

8. A gas turbine power plant comprising an air compressor, a fuel combustion chamber and a gas turbine driven by the hot gaseous products of combustion formed in said combustion chamber; said power plant having metal components subject to corrosion attack by compounds of vanadium, a supply of petroleum fuel containing vanadium, means including a fuel control for controlling the rate of injection of said fuel into said combustion chamber for combustion, a coil of tubular sheathed structure including a tubular sheath formed of material selected from one group and having a comminuted material containing material selected from another group disposed therein, said groups comprising: aluminum, chromium, iron, manganese, silicon, boron, titanium, zirconium, molybdenum and tungsten; and magnesium, beryllium, calcium, barium, strontium and zinc; means including a variable speed drive mechanism for feeding said sheathed structure into said combustion chamber at a variable rate, and an integrating controller responsive to at least one power plant operating characteristic for controlling the speed of said variable speed drive mechanism.

References ited in the file of this patent UNITED STATES PATENTS 2,399,680 Keefer May 7, 1946 2,781,005 Taylor et al Feb. 12, 1957 7 2,844,112 Muller July 22, 1958' 2,890,108 Toulmin June 9, 1959 FOREIGN PATENTS 1,102,480 Canada May 11, 1955 576,888 France June 2, 1959

Claims

1. A GAS TURBINE POWER PLANT COMPRISING AN AIR COMPRESSOR, A FUEL COMBUSTION CHAMBER AND A GAS TURBINE DRIVEN BY THE GASEOUS PRODUCTS OF COMBUSTION FORMED IN SAID CHAMBER, SAID GAS TURBINE HAVING METAL COMPONENTS SUBJECT TO CORROSION ATTACK BY COMPOUNDS OF VANADIUM, SODIUM AND SULPHUR, MEANS FOR INJECTING A PETROLEUM FUEL CONTAINING ONE OR MORE OF THE ABOVE COMPOUND FORMING ELEMENTS INTO SAID COMBUSTION CHAMBER FOR COMBUSTION PURPOSES, A COIL OF COMPOSITE ROD CONTAINING AT LEAST TWO MATERIALS IN PRESELECTED PROPORTIONS, ONE OF SAID MATERIALS BEING EFFECTIVE TO INHIBIT THE FORMATION OF AT LEAST ONE OF THE ABOVE COMPOUNDS AND FORMING ANOTHER COMPOUND AND THE OTHER OF SAID MATERIALS BEING EFFECTIVE TO MINIMIZE THE DEPOSITION OF SAID ANOTHER COMPOUND ON SAID TURBINE COMPONENTS, MEANS FOR FEEDING SAID ROD DIRECTLY INTO SAID COMBUSTION CHAMBER, AND MEANS FOR CONTROLLING SAID FEEDING MEANS IN ACCORDANCE WITH AN OPERATING CONDITION OF SAID POWER PLANT.