US3342241A

US3342241A - Combustion apparatus

Info

Publication number: US3342241A
Application number: US496993A
Authority: US
Inventors: John S Whitesides
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1965-10-18
Filing date: 1965-10-18
Publication date: 1967-09-19
Anticipated expiration: 1984-09-19

Description

Sept. 19, 1967 J. S. WHITESIDES COMBUSTION APPARATUS 2 Sheets-Sheet 1 Filed Oct 18, 1965 FIG.

GAS TURBINE INVENTOR J. 5. WHITE SIDES ATTORNEYS FIG. 2

P 1967 r J. 5. WHITESIDES 3,342,241

COMBUSTION APPARATUS Fild Oct. 18, 1965 2 Sheets-Sheet 2 l3 FUEL 8. AIR

INVENTOR J. S.WHITES1DES FIG. 3

ATTORNEYS United States Patent 3,342,241 COMBUSTION APPARATUS John S. Whitesides, Borger, Tex., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Oct. 18, 1965, Ser. No. 496,993 6 Claims. (Cl. 158-7) This invention relates to the recovery of heat. In one aspect, this invention relates to a method of and apparatus for recovering the heat in exhaust gases. In another aspect, this invention relates to methods of and apparatus for burning a fuel gas to recover heat therefrom. In a further aspect, this invention relates to burner tips for distributing a fuel gas or the like.

Many power plant installations utilize a gas turbine for generating the power required. The natural products of combustion in the form of exhaust gases including free oxygen pass from the gas turbine at a temperature of 700 F. or higher. Except for the use of a small amount of this heat for preheating boiler feed water and the like, the heat in the exhaust gases is usually not recovered. Although attempts have been made to utilize the oxygen in the exhaust gases to support combustion of fuel used to supply heat to a boiler, direct attempts to directly utilize the oxygen in the exhaust gases for supporting combustion to raise the temperature of the exhaust gases themselves have not been successful in the art. The reason it is difficult to raise the temperature of the exhaust gases is because it is almost impossible to initiate combustion in the exhaust gas stream as it leaves the gas turbine because of its high velocity.

According to this invention, these and other disadvantages of the prior art methods and apparatus for recovering heat from high temperature exhaust gases are overcome by providing a novel apparatus for effecting a combustion zone in the exhaust gases and for recovering the heat produced thereby. Another feature of this invention includes a novel burner tip which can be used to supply fuel gas to the stream of exhaust gases in a manner whereby the fuel gas remains ignited even though the exhaust gas is moving at a very high velocity.

The novel apparatus of this invention comprises a duct means adapted to receive and transmit exhaust gases, a first bank of burners carried by the wall of said duct means .and arranged in a substantially common plane which is substantially transverse with the duct means, a second bank of burners spaced downstream from the first bank of burners and carried by the walls of the duct means in a substantially common plane substantially transverse with the duct means, fuel supply means connected to each of the first and second banks of burners for supplying fuel thereto, and heat exchange means connected to the duct means downstream from the second bank of burners for recovering the heat in the exhaust gases passing through the duct means. The duct means of this invention can be connected to a gas turbine to receive the exhaust gases therefrom or to a gas expander. The novel burner tip which can be used in connection with the heat recovery system of this invention comprises a tubular body portion having .an inlet end for receiving fuel and an outlet end for discharging fuel, a shoulder disposed within the tubular body portion, and means defining a plurality of passageways each of which extends from the shoulder toward the outlet end of the tubular body. Each 3,342,241 Patented Sept. 19, 1967 of the passageways serves to allow fuel to be projected from within the tubular body in the same general direction as the fuel discharged from the outlet end of the tubular body.

Accordingly, it is an object of this .invention to provide a method of and apparatus for recovering heat from exhaust gases.

Another object of this invention is to provide a method of and apparatus for recovering heat from the exhaust gases from a gas turbine.

Still another object of this invention is to provide a method of and apparatus for projecting a flame a maximum distance with a minimum degree of bending into the stream of exhaust gases from a gas turbine.

A further object of this invention is to provide a burner tip which will retain a flame in high velocity gas streams.

Still another object of this invention is to provide a burner tip which will produce an easiiy ignitable gas fuel.

A still further object of this invention is to provide a method and apparatus which eliminates temperature differentials across the exhaust gas stream of a gas turbine.

Another object of this invention is to raise the temperature of the exhaust gases from a gas turbine, and to recover the heat therefrom.

These and other objects of the invention will become apparent to one skilled in the art after studying the following detailed description, the appended claims, and the accompanying drawings in which:

FIGURE 1 is a diagrammatic illustration of a gas turbine and an exhaust duct for transmitting the products of combustion from the gas turbine;

FIGURE 2 is a cross-section of the exhaust gas duct taken along the line 22 of FIGURE 11;

FIGURE 3 is a detail view partially in section showing a burner mounted through the wall of the exhaust duct in accordance with the invention; and

FIGURE 4 is a partial cross-section of a burner tip constructed in accordance with this invention.

Referring now to the drawings wherein like reference numerals are used to denote like elements, and particularly to FIGURES 1 and 2, the invention will be described in more detail. A gas turbine 10 is mounted to receive hot gases from a combustor (not shown). The hot gases are expanded within the turbine and discharged by means of conduit 11 into a duct means 12 which will serve to transmit them to atmosphere. The duct 12 is provided with

linings

13 and 14 of refractory material which serve to protect the outer shell of the duct 12 from the heat and to prevent heat loss.

The normal products of combustion discharged from a gas turbine contain about 18% oxygen. In accordance with this invention, it has been discovered that the temperature of the exhaust gases can be raised by utilizing the oxygen in the products of combustion to burn a fuel gas in the stream of exhaust gases. This can be accomplished by positioning a first bank of burners, shown generally by reference numeral 16, through the walls of the duct 12. A second bank of burners, shown generally by reference numeral 17, is spaced downstream from the first bank of burners through the walls of the duct 12. The burners in each of the banks 16 and 17 are arranged in a substantially common plane which is substantially transverse with the longitudinal axis of the duct 12. The first bank of burners '16 comprises a plurality of individual burners 18 positioned radially through and circumferentially spaced around the duct 12. The second bank of burners 17 comprises a plurality of individual burners 19 positioned radially through and circumferentially spaced around duct 12 downstream from the first bank of burners.

Referring more particularly to FIGURE 2, it can be seen that the individual burners 19 in the second bank of burners 17 are offset with respect to the individual burners 18 in the first bank of burners 16 in the sense that none of the burners lie in the same longitudinal plane. Thus, with each bank of burners 16 and 17 comprising ten individual burners, as illustrated, when the burners are circumferentially spaced an equal distance apart, there is a space of about 36 between adjacent burners. By offsetting the second bank of burners 17 with respect to the first bank of burners 16 as shown, the net distance between the individual burners in bothbanks of burners is reduced to about 18. This construction results in a more uniform distribution of the flame into the exhaust gases thereby decreasing the temperature differential across the exhaust gases as they pass through duct 12.

A heat exchanger 21 in the form of a helical tube having an inlet tube 22 and an outlet tube 23 is connected to and mounted within the duct 12 downstream from the second bank of burners 17. This will allow a fluid to be heated by the hot exhaust gases as it is circulated through the helical tube of the heat exchanger 21.

Referring now to FIGURE 3 of the drawings, a burner of the

type

18 and 19 in FIGURE 1 of the drawings is illustrated in detail. A cylinder 24 constructed of a refractory material or the like is carried by the inner surface of the duct 12 such that the flared portion of the cylinder is oriented toward the center of the duct. A plurality of radial passageways 26 is provided through the walls of the cylinder 24. A conduit 27 mounted exteriorly of the duct 12 is positioned in fluid communication with cylinder 24. Means including a pipe 28 having a valve 29 is operatively connected in fluid communication with conduit 27 for supplying a combustible mixture of fuel and air for the purpose of initiating combustion of the main fuel. An igniter 31 positioned to extend through the surface of pipe 28 will serve to supply a spark to initiate combustion of the fuel and air mixture.

Each of the

burners

18 and 19 is provided with means for receiving fuel in order to sustain combustion after the fuel and air mixture entering through pipe 28 is ignited. This means'includes a fuel delivery pipe 32 with a valve 40 therein and a burner tip 33 attached thereto. A tubular housing 45 mounted within conduit 27 by means of a plurality of spokes 35 serves to house the fuel delivery pipe 32 and the burner tip 33 such that the burner tip is positioned substantially along the longitudinal axis of cylinder 24.

The burner tip 33 of this invention is illustrated in more detail in FIGURE 4 of the drawings and comprises 'a tubular body portion having a cylindrical inlet end 34 and a frusto-conical outlet end 36. The cylindrical inlet end 34 can be provided with threads or the like such that it can be attached to the fuel supply conduit. If desired, the tip 33 can be attached to the fuel supply conduit 32 by welding. The frusto-conical outlet end 36 for discharging fuel from the burner tip 33 has an interior surface substantially parallel with the frusto-conical exterior surface. A shoulder 37 is disposed within the tubular body at substantially the juncture between the cylindrical inlet end 34 and the frusto-conical outlet end 36. A pair of parallel passageways 38 disposed within the frusto-conical outlet end 36 of the tubular body extend from the shoulder 37 through the frusto-conical outlet end in a direction substantially parallel with the longitudinal axis of the burner tip 33.

The shoulder 37 of the burner tip 33 can be at any convenient angle with the interior surface of the burner tip i so long as a smooth transition of the flowing ga between the cylindrical inlet end and the frusto-conical outlet end of the burner tip is maintained. Thus, the shoulder can be at an angle of between about 15 and about 75 with a plane transverse to the cylindrical inlet end of the burner tip. This range corresponds to an included angle range between the shoulder 37 and the interior surface of the cylindrical inlet end of between about and about The interior surface of the frusto-conical outlet end 36 of the burner tip 33 can be at any convenient angle which will provide the decrease in the size opening necessary to increase the velocity of the fuel gas. For convenience, it is preferred that the interior surface of the frusto-conical outlet end be at an angle of about 80 with a plane transverse to the cylindrical inlet end of the burner tip. This angle corresponds to an included angle between the interior surface of the frusto-conical outlet end and the interior surface of the cylindrical inlet end of In the operation of the invention, exhaust gases from gas turbine 10 containing approximately 18% oxygen and at a temperature of about 750 F. are introduced into duct means 12 and passed therethrough at hurricane velocity of about 110 feet per second. A fluid such as butane or the like which is to be heated can be circulated through helical heat exchange tube 21 by any suitable pumping means (not shown). The individual burners 18 and '19 can be ignited by introducing a mixture of fuel and air through pipe 28. Igniter 31 can be used to ignite the combustible mixture whereupon flame will be emitted from cylinder 24. The main fuel mixture can then be introduced through fuel delivery pipe 32 and burner tip 33 whereupon it will become ignited. After the fuel being delivered from fuel delivery pipe 32 is ignited, the fuel and air mixture supp-lied through pipe 28 can be discontinued. The oxygen carried in'the exhaust gases from the gas turbine will serve to support combustion of the fuel. By igniting all of the

burners

18 and 19, the temperature of the exhaust gases can be raised by 400 Fahrenheit degrees or more.

The burner tips of the invention and their association with the cylinders 24 and duct 12 result in a flame having maximum projection into the duct with a minimum amount of flame bending in the direction the exhaust gases travel. This result can be largely attributed to the effect obtained by the shoulder 37 and its association with the passageways 38. When the fuel passes through'the burner tip 33, the layer of fuel adjacent the interior surface of the cylindrical inlet end 34 passes smoothly over the shoulder and along the surfaces of the frusto-conical outlet end. A portion of this layer of fuel-passes through passageways 38 such that when this portion leaves passageways 38 it serves to maintain the main flame emanating from the outlet end in a straight line. By not allowing the outermost layer of fuel to become broken up before it exits from the burner tip, which is made possible by the presence of the shoulder 37, a much smoother flow of fuel through the burner tip is achieved, and a much longer and more durable flame projection is achieved. Moreover, the fuel passing from passageways 38 serves as a constant source of ignition for the fuel exiting through the frusto-conical outlet end of the burner tip. This advantage allows the fuel to be more easily ignited even when the exhaust gases are traveling at hurricane velocity. Thus, in the event the fuel pressure is reduced such that the flame is extinguished, it is easier to ignite the fuel issuing from the flame retention passageways 38.

Another important advantage realized by the method and apparatus of this invention is the elimination of hot and cold spots within the exhaust gases in the duct means. This result can be attributed to the presence of the

burners

18 and 19 in their offset relationship.

The following example will serve to illustrate the utility and operability of the invention. It must be understood that this example is for the purpose of illustrating typical operating conditions and must not be considered to be limiting of the invention.

Example In the apparatus illustrated in FIGURES 1 and 2 using the burners of FIGURES 3 and 4, stable combustion was attained at the following rates and conditions:

Total fuel 1 added to all burners (32):

Heated total admixture (before Temperature, F.

1 Primarily methane.

Although the invention has been described in considerable detail, it must be understood that such detail is for illustration purposes only and must not be considered limiting of the invention.

I claim:

1. Apparatus for recovering waste heat from exhaust gases comprising duct means adapted to be connected to a gas turbine for receiving and transmiting exhaust gases therefrom; a first bank of burners carried by the walls of said duct means and arranged in a substantially common plane substantially transverse therewith; a second bank of burners positioned downstream from said first bank of burners and carried by the walls of said duct means and arranged in a substantially common plane substantially transverse therewith, each of the burners in said first and said second banks of burners comprising a cylinder carried by the inner surface of said duct means, a conduit carried exteriorly of said duct means in fluid communication with said cylinder, means connected to said conduit for supplying a combustible mixture of fuel and air thereto, and means within said conduit for projecting fuel into said cylinder and said duct means; means connectedto said first and said second banks of burners for supplying fuel thereto; and heat exchange means connected to said duct means downstream from said second bank of burners for recovering the heat in the exhaust gases passing through said duct means.

2. Apparatus according to claim 1 wherein said cylinder of said burner is provided with a plurality of radial passageways extending through the walls thereof.

3. Apparatus according to claim 1 wherein said means within said conduit for projecting the fuel into said cylinder and said duct means includes a tubular housing mounted longitudinally within said conduit; a fuel delivery pipe positioned within said housing; and a burner tip attached to said fuel delivery pipe.

4. Apparatus according to claim 3 wherein said burner tip comprises a tubular body portion having an inlet end for receiving fuel and an outlet end for discharging fuel; a shoulder disposed within said tubular body; and means defining a plurality of passageways each of which extends from said shoulder toward the outlet end of said tubular body for allowing fuel to be projected from said tubular body in the same general direction as the fuel discharged from the outlet end of said tubular body.

5. Apparatus for recovering waste heat from exhaust gases comprising duct means adapted to receive and transmit exhaust gases; a first bank of burners carried by the walls of said duct means and arranged in a substantially common plane substantially transverse therewith; a second bank of burners positioned downstream from said first bank of burners and carried by the walls of said duct means and arranged in a substantially common plane substantially transverse therewith, each of the burners in said first and second banks of burners comprising a cylinder carried by said duct means, a conduit positioned exteriorly of said duct means in fluid communication with said cylinder, means connected to said conduit .for supplying a combustible mixture of fuel and air thereto, and means within said conduit for projecting fuel into said cylinder and said duct means; means connected to said first and said second banks of burners for supplying fuel thereto; and heat exchange means connected to said duct means downstream from said second bank of burners for recovering the heat in the exhaust gases passing through said duct means.

6. Apparatus for recovering waste heat from exhaust gases comprising duct means to receive and transmit exhaust gases; a first bank of burners carried by the Walls of said duct means and arranged in a substantially common plane substantially transverse therewith; a second bank of burners positioned downstream from said first bank of burners and carried by the wall of said duct means and arranged in a substantially common plane substantially transverse therewith, the individual burners of said second bank of burners being offset with respect to the individual burners of said first bank of burners such that the individual burners of said second bank of burners lie in longitudinal planes different from the longitudinal planes occupied by the individual burners of said first bank burners; means connected to said first and said second banks of burners for supplying fuel thereto; and heat exchange means connected to said duct means downstream from said second bank of burners for recovering the heat in the exhaust gases passing through said duct means and wherein each of the burners in said first and said second banks of burners comprises a cylinder carried by the inner surface of said duct means; a conduit carried exteriorly of said duct means in fluid communication with said cylinder; means connected to said conduit for supplying a combustible mixture of fuel and air to initiate ignition of the fuel; and means within said conduit for projecting the fuel into said cylinder and said duct means.

References Cited UNITED STATES PATENTS 1,380,507 6/1921 Wallace 239-566 X 1,508,718 9/ 1924 Peabody l58-1.5 1,790,908 2/ 1931 Fitts 239552 1,824,820 9/1931 Hynes 23712.3 2,444,851 7/1948 Rogers 239548 2,840,049 6/1958 Durham 122-7 2,898,093 8/1959 Severson 239-548 X FREDERICK L. MATTESON, JR., Primary Examiner. E. G. FAVORS, Assistant Examiner.

Claims

1. APPARATUS FOR RECOVERING WASTE HEAT FROM EXHAUST GASES COMPRISING DUCT MEANS ADAPTED TO BE CONNECTED TO A GAS TURBINE FOR RECEIVING AND TRANSMITING EXHAUST GASES THEREFROM; A FIRST BLANK OF BURNERS CARRIED BY THE WALLS OF SAID DUCT MEANS AND ARRANGED IN A SUBSTANTIALLY COMMON PLANE SUBSTANTIALLY TRANSVERSE THEREWITH; A SECOND BANK OF BURNERS POSITIONED DOWNSTREAM FROM SAID FIRST BANK OF BURNERS AND CARRIED BY THE WALLS OF SAID DUCT MEANS AND ARRANGED IN A SUBSTANTIALLY COMMON PLANE SUBSTANTIALLY TRANSVERSE THEREWITH, EACH OF THE BURNERS IN SAID FIRST AND SAID SECOND BANKS OF BURNERS COMPRISING A CYLINDER CARRIED BY THE INNER SURFACE OF SAID DUCT MEANS, A CONDUIT CARRIED EXTERIORLY OF SAID DUCT MEANS IN FLUID COMMUNICATION WITH SAID CYLINDER, MEANS CONNECTED TO SAID CONDUIT FOR SUPPLYING A COMBUSTIBLE MIXTURE OF FUEL AND AIR THERETO, AND MEANS WITHIN SAID CONDUIT FOR PROJECTING FUEL INTO SAID CYLINDER AND SAID DUCT MEANS; MEANS CONNECTED TO SAID FIRST AND SAID SECOND BANKS OF BURNERS FOR SUPPLYING FUEL THERETO; AND HEAT EXCHANGE MEANS CONNECTED TO SAID DUCT MEANS DOWNSTREAM FROM SAID SECOND BANK OF BURNERS FOR RECOVERING THE HEAT IN THE EXHAUST GASES PASSING THROUGH SAID DUCT MEANS.