US3311154A - Fuel burners - Google Patents

Description

March 1967 D. ca. H. SUMPTER FUEL BURNERS 6 Sheets-Sheet 1 Filed May 20, 1965 March 28, 1967 D. a. H. SUMPTER 3,

FUEL BURNERS Filed May 20, 1965 6 Sheets-Sheet 2 I' I I I II B l 00 (IL I a [a I la I I W46 1 I L I I I w March 3, 1967 D. G. H. SUMPTER FUEL BURNERS 6 Sheets-Sheet 5 Filed May 20, 1965 March 28, 1967 D. G. H. SUMPTER FUEL BURNERS e sheets-shat 4 Filed May 20, 1965 March 1967 D. G. H. SUMPTER 3,

FUEL BURNERS Filed May 20, 1965 6 sheets sheet 5 March 28, 1967 I D. G. H. SUMPTER 3,311,154

FUEL BURNERS Filed May 20, 1965 6 Sheets-Sheet 6 United States Patent Ofiice 3,311,154 Patented Mar. 28, 1967 3,311,154 FUEL BURNERS David George Henry Sumpter, Drayton, England, assignor to Associated British Combustion Limited, Portchester, Hampshire, England, a British company Filed May 20, 1965, Ser. No. 457,305 Claims priority, application Great Britain, May 25, 1964, 21,429/ 64 3 Claims. (Cl. 158-4) This invention relates to fuel burners and to boiler arrangements incorporating the same suitable for large industrial boilers of the power station type.

The invention is more especially concerned with boilers which are fed from the front by means of banks of burners.

Hitherto these have taken the form of individual burners with separate ducting arrangements for supplying each of them with the necessary combustion air. Also control arrangements have been provided so that each burner can be switched on or of separately.

Each individual burner has had its separate aperture at the boiler front the boiler tubes being bent around these apertures within a frusto-conical collar.

Special bafiling arrangements are also required derived from model studies to ensure that each burner receives its correct air supply. This is necessary to ensure that there is a minimum excess of oxygen (of the order of 0.5%) or less in the combustion gas in accordance with modern specifications.

To supply air to the complex baflling system satisfactorily it has been necessary to use a fairly low air velocity, say not more than 40 ft./sec. since otherwise the air velocity tends to cause variation of air supply to the individual burners. This has made it necessary to provide a considerable depth of casing in order to give an adequate air supply.

The type of burner used has therefore of necessity been of some considerable length.

The burners extending through the deep casings cause considerable difficulties in suspending the burners and allowing for expansion and contraction owing to large differences in temperature at the inside and the outside faces of the casing.

In the case of oil fuel burners, with recent increases in the size of boilers and tendency to use larger burners for these, further difiiculties have arisen in that the oil pressure output to maintain a given oil particle size increases with size of burner. With the increase in burner size occurring for the reasons given above the resulting higher oil pressures require more expensive pumping provisions.

The present invention consists in an oil burner arrangement for boilers in which the burners are arranged in separate cells each cell comprising a plurality of burners with a common air supply.

The burners in each cell may be operated together, thus reducing the number of elements in the control systern.

Conveniently two adjacent rows of cells are provided, one row with its air supply from the top and the other row with its air supply from the bottom.

The invention further consists in a fuel burner cell in the form of a generally rectangular box or casing with the burners disposed in a line centrally of the box and extending from the center part of one end towards the center part of the other end.

The outlet ends of the individual burners will conveniently be enclosed in open ended ducts of increasing length proceeding from the burner nearest the air inlet whereby the air is distributed evenly to each burner, and

suitable baffles may be provided to aid in this distribution.

The cell wall may be conveniently sloped inwardly at the end through which spraying ends of the burners project.

The bottom (or top) will form the inlet for air and be closable by means of valves.

The use of a multiplicity of separate cells simplifies the model study requirements and air flow patterns in that each cell once designed functions in exactly the same way and the problem of dividing the main air flow of a duct between the respective cells leading off from it becomes a relatively simple one, particularly as the air may be supplied at each end of each of the two ducts supplying the top and bottom cells respectively.

In view of this simplification of air flow pattern the air velocities may be increased without disturbing the flow pattern and this enables a reduction of the front to back dimensions, i.e. between the boiler wall and the outside wall and hence of the lengths of burners extending therebetween.

The problems arising from suspension of the burners and differential heating effects are thus reduced and in the case of oil burners the oil pressures required may be considerably reduced. Also, the flame lengths may be short and the flame shapes more readily adapted to furnace configuration.

A further advantage of the use of individual burner cells is that each cell is independent as required expansion effects which are therefore minimised.

The invention will be further described with reference to the accompanying drawings, thus taking an oil fuel burner installation by way of example.

FIGURE 1 is a Side elevation in partial section of a cell according to the invention;

FIGURE 2 is an end elevation of the same in partial section;

FIGURE 3 is a section on the line IIIIII of FIG. 1;

FIGURE 4 is an end elevation of the front of the lower end of a boiler supplied by means of banks of the cells;

FIGURE 5 is a side elevation of the same in partial section;

FIGURE 6 shows a modified form of the baffles of FIGURE 1;

FIGURE 7 is a cut-away perspective view from inside a cell modified for use with gas; and

FIGURE 8 is a similar cut-away perspective view from inside the furnace looking on the end of the cell.

The cells each comprise a generally rectangular boxor casing 1 with a front wall, spaced side walls including a first portion extending from opposite lateral ends of the front .wall, to mutually inclined portions leading to third and paralled portions defining a central vertical slot or passage.

From front to back of the box there extend six superposed burners or sprayer bodies 2 centrally disposed in the front walls and parallel to the first and third portions of the side walls and with radial baffles 2a of an air swirler at their exit ends projecting through the slot or passage, and associated with guide vanes 2b. The uppermost burner (as shown) is adjacent the top end (as shown) and the lowermost burner is some two thirds of the way down the box. Two of the burners are provided with igniters 20.

At the bottom of the box are provided valves 3a with resiliently flexible margins 3b for controlling the air supply and disposed in a separate damper box 3 which may be extracted from the cell 1 and as shown is shorter than the cell front to back with the bottom or partial base wall of the cell being extended to lead to it.

Each burner from its exit end towards its entry end is enclosed within a rectangular duct 4 the length of which increases from the lowermost burner towards the uppermost. These ducts defined by horizontal dividers extending between the side walls and which ducts have open ends within the box lying in an inclined plane roughly diagonal in relation to the box; These ducts or passages surround the respective burners and constrain the air to flow around the individual burners through the outlet slot.

This provides for separate equal air streams to each burner. The dimension of the air into equal streams may be assisted by suitably placed baffies 4a curving towards the damper box.

A duct 1a supplies cooling air to a main pipe 112 with branches 10 by which the cooling air is fed to each burner.

As shown in FIGURES 4 and 5 in a particular installation, twenty of these cells are arranged side by side in two rows of ten at the front of the boiler.

The uppermost ends of the cells as described are adjacent in the two rows.

Each burner in a cell is supplied from an automatic oil valve 5 from an oil fuel manifold 6.

Steam manifold 7 respectively supplies automatic steam valves 8 which also supply the burners of the respective cells.

The valves 3 of the respective cells are supplied from upper and lower ducts or air casings 9, 10, respectively.

Suitable bafiies or air guides 11, 12 (corresponding to 4a) may be provided within the cells.

Coupling blocks 13 are fitted on the outer ends of the burners to connect to the oil supply.

The boiler tubes 14 for each pair of top and bottom cells as shown in FIGURES? and 4 are bent into overlaping relationship to form one vertical slot for the twleve burners of the two cells.

The invention may also be used to cater for gas firing, both using this fuel alone and with a combination of gas and oil. The way in which this may be done is shown in FIGURES 7 and 8.

Gas is introduced by means of a flanged connection 15, into a volume formed by the double skinning on both sides of the cell at the forward end. The gas is led from this space by means of contoured louvres 16, which adjoin the inside skin of the cell and are shaped forward to form an annular gas space around the outside diameter of each burner swirler. The gas passing through this annular ring is deflected by a series of angled vanes 17 before being burnt.

Various modifications may be made within the scope of the invention. Thus, with suitable modifications the arrangement described may be modified for burning pulverised fuel. Also, the number of burners can be from two upwards, the most usual numbers being three, four, five, six or seven. The number of igniters could vary from one per cell to one per sprayer.

The number of cells per boiler may vary from two upwards.

Various types of atomisers and sprayers can be used. These are:

(1) Mechanical atomisers relying on fuel pressure alone.

(2) Atomisers relying on steam pressure.

(3) A combination of (1) and (2) known as the steam-assisted atomiser.

(4) Mechanical atomisers of the wide range type where the flow is controlled by either leaking off oil from within the whirl chamber, or by means of an adjustable pintle, or combination of slots in the oil passages.

- I claim:

1. Ina fuel burner construction, a burner cell comprising a rectangular casing including a front wall, an end wall, a partial base wall parallel to the said end wall and remote from the front wall and spaced side walls including parallel portions and converging portions defining a slot along the center line of the casing, said slot having substantially less transverse dimension than the corresponding dimension of the casing, a plurality of burners extending into the casing in superposed relation along the vertical center line thereof, means mounting the burners in the front wall, each burner having a delivery and extending through said slot, vertically spaced horizontally arranged dividers extending between the side walls in alternating arrangement with said burners and cooperating with said end wall, said side walls and partial base wall to define a rectangular passage around each burner, said dividers increasing in length from said base wall toward said end wall, and valve controlled conduit means communicating with said casing between said front wall and partial base wall for introducing air into said casing whereby it is distributed by said dividers to flow through said slot around the respective burners.

2. In a fuel burner construction as claimed in claim 1, said valve controlled conduit means comprising wall means communicating with the cell between the side, front and partial base walls, and a removable damper box associated with said wall means and having damper valves therein for controlling air flow to said cell.

3. In a fuel burner construction, a burner cell comprising a rectangular casing including a front wall, spaced side walls and an end wall, each side wall including a first portion extending away from one lateral edge of the front wall and parallel to the first portionof the other side wall, a second portion inclined toward the opposite side wall and a third portion extending to an outlet and parallel to the third portion of the other side wall to define therewith an elongated rectangular vertically extending outlet slot, said casing also including a partial base wall extending rearwardly of said slot toward and terminating short of said front wall, a plurality of burners extending through the casing in superposed relation along the vertical center line thereof, said slot having substantially less transverse dimension than the corresponding dimension of the casing, means mounting each burner in the front wall, each burner having a delivery end extending through said slot, vertically spaced horizontally arranged dividers eX- tending between said side walls and in alternating arrange ment with said burners and cooperating with said end wall, said side walls and partial base wall to define a rectangular passage around each burner, said dividers increasing in length from said base wall toward said end wall, and valve controlled conduit means communicating with said casing between said front wall and partial base wall for introducing air within the cell wherein it is constrained by said dividers to flow through said passages to form separate exit streams through said slot around the individ ual burners.

References Cited by the Examiner UNITED sTATEs PATENTS 474,344 5/1892 Ramsay 158-74 2,392,822 1/1946 Kuhner 122-235 3,135,314 6/1964 Brunner 158-11 3,202,196 8/1965 Rackley et a1. 158-15 FOREIGN PATENTS 266,827 3/1927 Great Britain.

FREDERICK L. MATTESON, ]R., Primary Examiner,

E. G. FAVORS, Assistant Examiner.

Claims (1)

1. IN A FUEL BURNER CONSTRUCTION, A BURNER CELL COMPRISING A RECTANGULAR CASING INCLUDING A FRONT WALL, AN END WALL, A PARTIAL BASE WALL PARALLEL TO THE SAID END WALL AND REMOTE FROM THE FRONT WALL AND SPACED SIDE WALLS INCLUDING PARALLEL PORTIONS AND CONVERGING PORTIONS DEFINING A SLOT ALONG THE CENTER LINE OF THE CASING, SAID SLOT HAVING SUBSTANTIALLY LESS TRANSVERSE DIMENSION THAN THE CORRESPONDING DIMENSION OF THE CASING, A PLURALITY OF BURNERS EXTENDING INTO THE CASING IN SUPERPOSED RELATION ALONG THE VERTICAL CENTER LINE THEREOF, MEANS MOUNTING THE BURNERS IN THE FRONT WALL, EACH BURNER HAVING A DELIVERY AND EXTENDING THROUGH SAID SLOT, VERTICALLY SPACED HORIZONTALLY ARRANGED DIVIDERS EXTENDING BETWEEN THE SIDE WALLS IN ALTERNATING ARRANGEMENT WITH SAID BURNERS AND COOPERATING WITH SAID END WALL, SAID SIDE WALLS AND PARTIAL BASE WALL TO DEFINE A RECTANGULAR PASSAGE AROUND EACH BURNER, SAID DIVIDERS INCREASING IN LENGTH FROM SAID BASE WALL TOWARD SAID END WALL, AND VALVE CONTROLLED CONDUIT MEANS COMMUNICATING WITH SAID CASING BETWEEN SAID FRONT WALL AND PARTIAL BASE WALL FOR INTRODUCING AIR INTO SAID CASING WHEREBY IT IS DISTRIBUTED BY SAID DIVIDERS TO FLOW THROUGH SAID SLOT AROUND THE RESPECTIVE BURNERS.

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