US3284008A - Burner - Google Patents

Description

Nov. 8, 1966 E. c. M |L,.LER 3,284,008

BURNER Filed Nov. 9, 1964 2 Sheets-Sheet l LOAD UPPER VANES vow/v UP GAS LOWER F IG 3 VANES UP DOWN UPPER DOWN DOWN EARLE 0.. MILLER VANES OIL LOWER INVENTOR.

VANES up UP 2 Sheets-Sheet 2 l-g CRJ BURNER E. C. MILLER "g/CR- l OFF Nov. 8, 1966 Filed Nov. 9, 1964 63 L41 LOW CRIS-I FIG. 2

EARLE C. MILLER INVENTOR BY W I w IFll! United. States Patent Office 3,284,968- Patented Nov. 8, 1966 3,284,008 BURNER Earle C. Miller, Worcester, Mass., assignor to Riley Stoker Corporation, Worcester, Mass., a corporation of Massachusetts Filed Nov. 9, 1964, Ser. No. 409,868 4 Claims. (Cl. 239-412) This invention relates to a burner and, more particularly, to apparatus arranged to produce hot products of combustion in a furnace to generate steam by burning oil or gas in suspension.

Many steam generating units are arranged to burn several types of fuel alternatively or at the same time. The selection of fuel to be burned at a particular time is usually determined by economics and by supply. Those steam generating units which are located close to oil-producing fields will have varying amounts of fuel oil and natural gas available for burning at various times. One of the difficulties experienced with this type of operation, however, is that the quality of the gases, the nature of the flame, and its amount of radiation to the heat exchange elements of the boiler vary with the type of fuel; this has a profound effect on the tempera-.

ture of superheat. It is important, of course, in using steam with a turbine-generator set that the steam be maintained at a constant, predetermined temperature and pressure. Steam generating units of the .past which have burned various types of fuel have experienced considerable ditficulty in maintaining superheat at the desired temperature; when fuels were changed, it was necessary for the boiler operator rapidly to make manual adjustments of the apparatus. If the apparatus were provided automatic superheat control, such as a spray de-superheater, it was necessary to reduce the superheat by considerable amounts with a resultant low efiiciency of the steam generating unit. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a burner capable of burning fuels of different quality without affecting the temperature of superheat.

Another object of this invention is the provision of a burner having means for regulating the burner, when the fuels are changed from one to another, in such a way as to produce a constant, predetermined gas tem perature in the convection superheater passes.

A further object of the present invention is the provision of a burner for gas and oil, which burner is of the inter-tube type having directional vanes in which the vanes are automatically adjusted to compensate for changes in temperature of gases passing over the superheaters at various loads with various fuels.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms as illustrated by the accompanying drawings in which:

FIG. 1 is a vertical sectional view of a burner embodying the principles of the present invention with some parts shown schematically,

FIG. 2 is an electrical schematic diagram showing an electrical control forming part of the invention, and

FIG. 3 is a chart showing the arrangement of burner vanes at different loads and with different fuels.

Referring first to FIG. 1, wherein are best shown the general features of the invention, the burner, indicated generally by the reference numeral 10, is shown in use with a steam generating unit 11 having water-Wall tubes 12 which are bent to provide an opening 13. A duct 14 approaches the steam generating unit from an air heater (not shown) and enters a wind box 16 surrounding the opening 13 and providing an air chamber 17. The air arriving in the duct 14 is controlled by a damper 15. Extending into the chamber 17 from the opening 13 is a shroud 18 which is divided by baflles 19 and 21 into a central passage 22, an upper passage 23, and a lower passage 24. Extending through the wind box 16, through the air chamber 17, and centrally of the central passage 22 is a burner gun 25. Located above the gun in the central passage 22 and in front of the upper passage 23 are adjustable vanes 28. Similar vanes 29 are lo cated in the opening of the lower passage 24 into the furnace and in the central passage 22 below the gun. A small damper 31 is located in the opening to the upper passage 23, while a similar damper 32 is located at the entrance into the lower passage 24. A linkage 33 connects the two dampers 31 and 32 to a linear actuator 34, such as a hydraulic cylinder for the adjustment thereof.

A rod 36 is connected to the upper vanes 28 for the regulation thereof and is operated by a reversible electric motor 35 operating through a worm-and-gear mechanism in the well-known manner. Similarly, a rod 37 is connected to adjust the angularity of the lower vanes 29 and this rod is moved by a reversible electric motor 38. An igniter 39 is mounted in the burner to assure ignition of the flame.

The burner 25 is connected to a gas pipe 26 and to an oil pipe 41. Extending through the burner and having its end lying in the furnace itself is an air pressure tube 44, while a similar tube 45 opens into the duct 14 ahead of the damper 15. The-diiferential pressure between these two tubes is connected to the opposite sides of the diaphragm 42 of an operator 43; this differential pressure is indicative of air flow to the burner.

Located in the oil pipe 41 is a valve 46 which, in the preferred embodiment, is of the ball type. This valve is operated from open to closed position by an air cylinder 47. Located on opposite sides of the actuating arm is an OIL OFF switch 48 and an OIL ON switch 49. In a similar way, the gas pipe 26 is provided with a valve 51 which is moved from open to closed position by an air cylinder 52, there being a gas OFF switch 53 mounted on the valve housing on one side of the operating arm and a gas ON switch 54 located on the other side of the operating arm of the valve. Mounted on the mechanism for moving the rod 36 are an UPPER VANES DOWN switch 55 and an UPPER VANES UP switch 56 in position to be engaged and closed by an actuating arm associated with the rod 36. In a similar way, mounted on the mechanism associated with the operation of the rod 37 are a LOWER VANES UP switch 57 and a LOWER VANES DOWN switch 58. The operator 43 is provided with a vertical stem 59 connected to the diaphragm 42 and this stem is provided with a laterally-extending pin 61 which is in position to contact a HIGH LOAD switch 62 in its upper movement and a LOW LOAD switch 63 in its downward movement. The upper end of the stem is connected through a rack-and-pinion mechanism to the sweep arm of a potentiometer 64. This potentiometer has its input connected to a source 65 of alternating current electricity, while its output is connected to a coil 66 of an electric servo valve 67. This servo valve serves to regulate the flow of oil from a high pressure oil source 68 to the cylinder 34.

Referring to FIG. 2, which shows the electrical arrangement of the apparatus, it can be seen that the apparatus is provided with two power lines 69 and 71 which are of widely-differing direct current electrical potential, as in the usual practice in this art. The GAS ON switch 54 3 is connected on one side to the line 69 and on the other side through the coil of a relay CR1 into the line 71. Similarly, the GAS OFF switch S3 is connected on one side to the line 69 and on the other side to the line 71 through the coil of a relay CR2. The OIL ON switch 49 is connected on one side to the line 69 and on the other side through the coil of a relay CR3 to the line 71. The OLL OFF switch 48 is connected on one side to the line 69 and on the other side through the coil of a relay CR4 to the line 71. The UPPER VANES UP switch S6 is connected on one side to the line 69 and on the other side through the coil of a relay CR5 to the line 71. The VANES DOWN switch 55 is connected on one side to the line 69 and on the other side through the coil of a re lay CR6 to the line 71. The LOWER VANES UP switch 57 is connected on one side to the line 69 and on the other side through the coil of a relay CR7 to the line 71, while similarly the LOWER VANES DOWN switch S8 is connected on one side to the line 69 and on the other side through the coil of a relay CR8 to the line 71. Furthermore, the HIGH LOAD switch 62 is connected on one side to the line 69 and on the other side through the coil of a relay CR9 to the line 71, while the LOW LOAD switch 63 is connected on one side to the line 69 and on the other side through the coil of a relay CR10 to the line 71.

The upper vanes motor 35 is shown as having an UP- WARD winding 72 and a DOWNWARD winding 73, one end of each being connected to the line 71. Similarly, the lower vanes motor 38 is shown as having an UP- WARD winding 74 and a DOWNWARD Winding 75, one end of each being connected to the line 71. Unless otherwise indicated, all contactors are of the normally open variety and are closed by the energization of the coil of their respective relays. Connected from the line 69 to the line 72 in series with one another are the following items: a contactor CR1-1, a contactor CR4-1, a contactor CR6-1, a contactor CR7-1, a contactor CR9-1, the coil of a relay CR11, and the UPWARD winding 72 of the motor 35. The common point between the contactor CR9-1 and the coil of the relay CR11 is connected to one side of a contactor CR111, the other side of which is connected through a normally-closed contactor CR5-1, the other side of which is connected to the line 69 to form a hold-in circuit for the relay CR11. Also extending in series between the line 69 and the line 71 are the following items: a contactor CR12, a contactor CR4-2, a contactor CR62, a contactor CR7-2, the coil of a relay CR12, a contactor CR9-2, and the UPWARD winding 72 of the motor 35. An intermediate point between the contactor CR7-2 and the coil of the relay CR12 is connected to one side of a contactor CR121, the other side of which is connected to one side of a contactor CR5-2, the other side of which is connected to the line 69 to form a holdin circuit for the relay CR12.

Connected from the line 69 to the line 71 are the following items in series: a contactor CR1-3, a contactor CRIB-2, a contactor CR43, a contactor CR5-3, a contactor CR8-1, the coil of a relay CR13, and the DOWN- WARD winding 73 of the motor 35. An intermediate point between the contactor CR8-1 and the coil of the relay CR13 is connected to one side of a contactor CR13-1, the other side of which is connected to the line 69 to form a hold-in circuit for the relay CR13. An intermediate point between the contactor CR4-3 and CR5-3 is connected to one side of a contactor CR31, the other side of which is connected to one side of a contactor CR10-2, which is connected through a contactor CR2-1 to the line 69.

Connected from the line 69 to the line 71 are the following items in series: contactor CR1-4, contactor CR10-4, contactor CR44, contactor CRS4, contactor CR8-2, the coil of a relay CR14 and the UPWARD winding 74 of the motor 38. An intermediate point between the contactor CR8-2 and the coil of the relay CR14 is connected to one side of a contactor CR14-1, the other side of which is connected through a normally-closed contactor CR73 to the line 69 to act as a holding circuit for the relay CR14. An intermediate point between the contactor CR4-4 and the contactor CR5-4 is connected through a contactor CR3-2, a contactor CR103, and a contactor CR22 to the line 69.

Connected from the line 69 to the line 71 are the following items in series: contactor CR15, contactor CR4-5, contactor CR6-4, contactor CR7-4, the coil of a relay CRIS, a contactor CR9-3, and the DOWN- WARD winding of the motor 38. A common point between the contactor CR7-4 and the winding of the relay CRIS is connected to one side of a contactor CRIS-1, the other side of which is connected through a normallyclosed contactor CR8-3 to the line 69 to act as a holdin circuit for the relay CRIS. The line 69 is also connected to the line 71 through the following items in series: a contactor CR1-6, a contactor CR4-6, a contactor CR6-5, a contactor CR7-5, a contactor CR9-4, and the coil of the relay CR16 and the DOWNWARD winding 75 of the motor 38. The common point between the contactor CR9-4 and the coil of the relay CR16 is connected to one side of a contactor CR161, the other side of which is connected through a normally-closed contactor CR8-4 to the line 69 to form a hold-in circuit for the relay CR16.

The operation of the burner 10 will now be readily understood in view of the above description, particularly in the light of the chart shown in FIG. 3. To begin with, it should be understood that the burner will give a narrow flame if the upper vanes 28 are directed downwardly and the lower vanes 29 are directed upwardly. Such a narrow flame will tend to cause less absorption of heat from the products of combustion in the furnace proper and, therefore, result in higher gas temperatures in the convection superheater passes and would result, therefore, in a higher temperature of superheat at a given load. On the other hand, when the upper vanes 28 are directed upwardly and the lower vanes 29 are directed downwardly, the result isa broad flame from which heat will be absorbed more readily in the furnace with resulting cooler gas temperatures in the superheater passes and lower temperature of superheat. While the burning of oil in the burner will give a temperature of superheat approximately the same, either at high or low load, irrespective of the settings of the vanes, when gas is burned in the burner a given setting of the vanes will produce a higher superheat at high load than at low load, giving a problem of correction, which is solved by the present inven tion.

Firstof all, the various switches in the apparatus give an indication of the condition of the burner at any given time. The switches 53 and 54 indicate whether or not the burner is provided with gas, the switches 48 and 49 indicate whether or not oil is being provided to the burner, the switches 55 and 56 indicate whether the upper vanes 28 extend in the upward direction or the downward direction, the switches 57 and 58 indicate whether the lower vanes 29 are directed in the upward or the downward direction, while the switches 62 and 63 indicate whether the steam generating unit is operating at high load or low load. For the purposes of clarity of explanation, low load is expressed as 25% of the rate of load of the steam generating unit, while high load is indicated as 75% of the load; as a practical matter, however, the switchover of the vanes would take place at some point between 25% load and 75% load. Let us suppose that the operation of the unit is being changed from the use of gas at low load to the use of gas at high load. The GAS ON switch 54 will be closed, the OIL OFF switch 48 will be closed, the upper vanes 28 will be directed downwardly before the change takes place, and this will be indicated by the fact that the UPPER VANES DOWN switch 55 will be closed and the LOWER VANES UP switch S7 will be closed. Before the change takes place, the LOW LOAD switch 63 will be closed. As the load goes up, LOW LOAD switch 63 will open and the HIGH LOAD switch 62 will be closed, while all other switches will remain as described above. An electrical circuit will be produced through one of the lines indicated by the numeral 1 in FIG. 2; that is to say, the contactor CR1-5 will be closed, the contactor CR45 will be closed, the contactor CR6-4 willbe closed, the contactor CR7-4 will be closed, and the contactor CR9-3 will become closed when the load goes to high. A circuit will be provided not only through the relay CRIS (which locks in through the contactor CR-1 and the normally-closed contactor CR8-3), but the current will also pass through the DOWNWARD winding 75 of the motor 38. This will cause the lower vanes motor 38 to be actuated in the downward direction. In a similar way, the upper vanes motor 35 will have its UPWARD winding 72 energized so that it will move in the upward direction because of current passing in the other line labelled 1 in FIG. 2 through the contactor CR1-t2, the contactor CR42, the contactor CR62, the contactor CR7-2, the coil of the relay CR14, the contactor CR92, and the UPWARD winding 72. The contactor CH12 is locked in through the contactor CH121 and the normally-closed contactor CR5-2. The movement of the upper vanes upwardly and the lower vanes downwardly will take place until the UPPER VANES UP switch 56 closes and the LOWER VANES DOWN switch 58 closes to shut off the motors. This is because the closure of the switch 56 opens the contactor CR5-2 and drops out the relay CR12. Current ceases to go through the winding 72 because, during the passage from high to low load, the UPPER VANES DOWN switch 55 has re-opened, thus de-energizing the relay CR6 and opening the contactor CR6-2, so that, once the lock-in circuit of the relay CR12 has been released, current can no longer flow through the winding 72.

The reverse process takes place when gas operation at high load changes to gas operation at low load. The elements that take part in this operation are shown in the lines numbered 2 in FIG. 2. The net result is that the upper vanes motor 75 is actuated downwardly and the lower vanes motor 38 is actuated upwardly until they reach their final positions and the UPPER VANES DOWN switch 55 is closed and the LOWER VANES UP switch 57 is closed to open up the lock-in circuits associated with the relays of these motors.

When oil operation at high load is changed to gas operation at high load, it is necessary to change the vanes again, and this is done through the elements shown in the lines numbered 3 in FIG. 2. The upper vanes motor 35 is actauted in the upward direction by the energization of the winding 72, while the lower vanes motor 38 is operated in the downward direction by the energization of the winding 75. These motors continue until the UPPER VANES UP switch 56 is closed and the LOWER VANES DOWN switch 58 is closed, in which case the hold-in circuits are dropped out. When the burner condition goes from gas operation at high load to oil operation at high load, the reverse process takes place and the elements in the lines numbered 4 in FIG. 2 take part in the operation. When the burner is changed from oil operation at low load to gas operation at high load, the elements in the lines numbered 5 in FIG. 2 take part in the operation. When the burner operation changes from gas operation at high load to oil operation at low load, the elements in lines numbered 6 in FIG. 2 take place in the operation.

When the switches indicate that the burner operation has gone from oil operation at low load to gas operation at low load there is no necessity to change the vanes and nothing happens in the electrical circuitry. In a similar way, when the burner condition is changed from gas operation at low load to oil operation at low load, nothing happens. When the burner operation is from oil operation at high load to oil operation at low load, or from oil operation at high load to oil operation at low load, no change in the vane condition takes place.

It can be seen, then, that the directional air vanes influence the angle at which the air enters the burner and mixes with the fuel. 'The upper set of vanes work independently of the lower set making many various combinations of combustion air influence obtainable. These directional vanes are used to influence final steam temperature conditions, among other things. Experience with gas and oil-fired burners indicates that two directionalvane positions can be used to approach the desired steam temperature conditions throughout the load range. Two positions are required for gas firing and one position for oil firing, of which the one oil firing position is identical to one of the gas firing positions. Operation on gas will be discussed first. With no gas flow the upper directional vanes will be in a downward direction and the lower directional vanes will be in an upward direction. This setting will produce higher steam temperatures with respect to other settings. At some point to be determined during initial operation (probably between one-half and threequarter load) the directional-vanes will be re-positioned. At this point, the upper vanes will be turned up and the lower vanes will be turned down. This vane position produces the lowest steam temperature when compared to other settings. The oil firing directional-vane position is identical to the low load gas position. Since there is a greater furnace heat absorption with oil firing, it is necessary to position the directional-flames to give as high a steam temperature as possible under all load conditions. This vane setting will accomplish this requirement. It can be seen that with dual fuel firing the predominant fuel will have the desired directional-vane setting to produce the required conditions regardless of boiler load.

The velocity control dampers 31 and 32 regulate th outlet area of the burner and, hence, the velocity of secondary air through the burner. An operator will be used to position these dampers and the burner differential pressure (which will be the controlling factor in damper positioning) will be the pressure drop obtained from the secondary air plenum chamber to the furnace. A velocity of about 7,000 feet per minute will be reached at peak load conditions. The velocity dampers will hold the burner dilferential (which is necessary to produce the desired velocity) down to approximately half load. Below this load point burner ,velocity will decrease, but will be of sufficient magnitude to produce the desired turbulent action for proper ignition of the fuel being fired. Since the velocity-control dampers are located in the upper and lower sections of the plenum chamber, a full closing of these dampers will result in a concentration of secondary air towards the horizontal centerline and will result in better air and fuel mixing at reduced loads. When load on the steam generating unit is increased, it is best (in accordance with well-known practice) to use opposed burners on both sides of the furnace in order to increase furnace turbulence. It is also important to select burners so as to maintain a good lateral balance of fuel put into the furnace.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. A burner for use with gas and oil, comprising (a) vanes which, in a first setting, give a narrow flame and, in a second setting, give a broad flame,

(b) a first means supplying gas to the burner,

(c) a second means supplying oil to the burner, and

(d) a third means associated with the first means, the

second means, and the vanes to provide the first setting for the vanes when the first means is operative at low load and when the second means is operative at either high or low load and to provide the second setting for the vanes when the first means is operative at high load.

2. An intertube burner, comprising (a) an upper and a lower set of vanes operative in a first setting with the upper vanes directed down wardly and the lower vanes directed upwardly to give a narrow flame, the vanes being operative in a second setting with the upper vanes directed upwardly and the lower vanes directed downwardly to give a broad flame,

(b) a first valve regulating the flow of gas to the burner, (c) a second valve regulating the flow of oil to the burner, (d) a load indicator giving a signal indicative of load,

and

(e) means associated with the va-nes to provide the first setting when the first valve is operative at low load and when the second valve is operative at either high or low load and to provide the second setting when the first valve is operative at high load.

3. An intertube burner as recited in claim 2, wherein a combination of gas gun and oil gun is located centrally of an opening into the furnace with which the burner is used, wherein dampers are provided to prevent the flow of air through the portions of the opening farthest removed above and below the guns at low load, whereby the flow of air is maintained below a predetermined value irrespective of load.

4. An intertube burner as recited in claim 2, wherein the said means consists of aGAS ON switch, a GAS OFF switch, an OIL ON switch, an OIL OFF switch, an UPPER VANES UP switch, an UPPER VANES DOWN switch, a LOWER VANES UP switch, a LOWER VANES DOWN switch, a HIGH LOAD switch, and 21 LOW LOAD switch, the said means also consisting of a first reversible motor responsive to the switches to move the upper vanes from upwardly-directed to downwardlydirected condition and vice versa, the said means also consisting of a second reversible motor responsive to the switches to move the lower vanes from upwardlydirected to downwardly-directed condition and vice versa.

No references cited.

EVERETT W. KIRBY, Primary Examiner.

Claims (1)

1. A BURNER FOR USE WITH GAS AND OIL, COMPRISING (A) VANES WHICH, IN A FIRST SETTING, GIVE A NARROW FLAME AND, IN A SECOND SETTING, GIVE A BROAD FLAME, (B) A FIRST MEANS SUPPLYING GAS TO THE BURNER, (C) A SECOND MEANS SUPPLYING OIL TO THE BURNER, AND (D) A THIRD MEANS ASSOCIATED WITH THE FIRST MEANS, THE SECOND MEANS, AND THE VANES TO PROVIDE THE FIRST SET-

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