US2244821A - Combustion apparatus - Google Patents

Description

June 10, 1941. s BLOOM 2,244,821

COMBUSTION APPARATUS Filed May 13, 1940 INVENTOR Patented June 10, 1941 .UNITED STATES PATENT OFFICE,

4 Claims.

This invention relates to fuel combustion, and in particular, to a method and apparatus for obtaining the desired distribution of air or other combustion-supporting gases delivered to a combustion space coincidently with a jet of combustible fluid such as gas, oil or the like.

In the art of measuring fluid flow, it is well recognized that at bends in a pipe line, there are eddies on the inside of the bend resulting from the tendency of the fluid to crowd to the outside of the bend, and normal or uniformly distributed flow is not resumed for some distance beyond the bend. This phenomenon is taken into account when measuring fluid flow in the pipe lines.

Fuel burners are frequently designed with elbows in the pipe lines supplying air thereto and with this construction the phenomenon mentioned results in poor distribution of the air in the combustion space which prevents a proper mixture of the fuel and air and reduces the efllciency of combustion. This problem is particularly serious in large burners using lowpressure air (1. e., air under a static pressure of from three to ten inches of water) in which the velocity head of the air in the supply line is a substantial proportion of the friction drop through the burner.

In a specific installation which I have tested, the air delivered through a burner port to a combustion space such as a furnace, flowed into the combustion space over only about one-third of the sectional area of the port. Over the remainder of the sectional area, the air flow was reversed because of eddies. Besides producing poor mixing of the air and fuel and poor combustion efliciency in the furnace, this condition caused the combustion gases to leave the burner at an angle of about 30 above the horizontal plane through the center line of the burner.

I have invented a novel combustion method and apparatus effective to prevent such improper and non-uniform distribution of the air in the combustion space as just described. In a preferred practice of the invention, I divide the air supplied to the burners into a plurality of strata and vary the flow through each stratum in such manner as to produce the desired distribution of air in the combustion space. The apparatus which I prefer to employ for practicing this method, comprises a plurality of fixed horizontal baflles or guide vanes disposed in the air inlet and adjacent the burner port opening into the furnace. I also provide a plurality of movable baffles or dampers for controlling the amount of air flowing from the supply pipe between each pair of adjacent guide vanes. The aforementioned preferred embodiment and practice of the invention are illustrated more or less diagrammatically in the accompanying drawing, in which Figure 1 is a vertical central sectional view through a burner according to my invention; and

Figure 2 is an end elevation of the burner, looking thereon from the furnace end.

Referring in detail to the drawing, I have shown at Hi for purposes of illustration only, a portion of the wall of a furnace or other en'- closure to be heated. A burner block H laid in the wall provides a port 12' through which combustion gases may be admitted to the furnace. A burner indicated generally at I3 is associated with the block II and comprises principally an elbow 14 having a neck l5 at the adjacent end thereof adapted to extend into the block II and a flange or collar I6 adapted to seat against the exterior of the wall |il. As indicated in Figure 2, the elbow I4 is of generally circular section and its outer end is adapted to be connected, as by bolts I! to an air supply pipe l8 extending upwardly to a suitable source of air or other combustion-supporting gas under relatively low pressure, i. e., three to ten inches of water.

An opening I 9 is formed in the end of the elbow substantially coaxial with the horizontal portion thereof. A cover plate 20 having a central boss 2| drilled and tapped to receive a threaded pipe is secured over the opening 19 by screws 22. A fuel supply pipe 23 is threaded into the boss 2| from the exterior. A short length of pipe 24 threaded into the boss from the interior provides a fuel nozzle effective to discharge combustible fluid into the port l2 from a suitable supply (not shown) to which the pipe 23 is connected through suitable control devices such as valves, as may be desirable;

Horizontal guide vanes or fixed baffles 25, 26 and 21 extend transversely of the horizontal portion of the elbow 14. These baffles extend rearwardly from adjacent the end of the hori-' zontal portion of the elbow l4 to about the 45 plane through the bend of the elbow. The baiiles are substantially uniformly spaced apart vertically and define parallel paths 28, 29, 30 and 3| through the horizontal portion of the elbow it. As shown, the length of the baffles is several times the distance between them.

Movable guide vanes or dampers 32, 33 and 34 are hinged to the vanes 25, 26 and 21 adjacent the rear edges thereof (the direction in which the air and fuel flow through the port I2 being considered the forward direction). The dampers 33 and 34 are notched as at 35 and 36 to clear the fuel nozzle 24. The dampers are rigidly secured to hinge pins 31, 3B and 39 journalled in suitable bearings 40 formed on the elbow l4. Levers 4| on the projecting ends of the hinge pins permit manual adjustment of the dampers and provision is made in any convenientmanner, for securing the dampers in any position to which they may be adjusted. The possible range of adjustment is shown by extreme positions of the dampers indicated in chain lines in Figure 1.

It will be apparent from the structure described above that air flowing downwardly through the supply pipe I 8 is divided into a plurality of strata which flow separately along the paths 28, 29, etc. The distribution of air in the several strata is determined by the adjustment of the dampers 32, 33 and 35. By shifting the damper 32 clockwise, the amount of air in the uppermost stratum is reduced and the amount of air in the remaining strata is increased, and vice versa. The air in the bottom stratum may be similarly controlled by shifting the damper 34 between its illustrated extreme positions. As a matter of fact, the air delivered along the path 30 may be almost entirely out off by shifting the damper 34 clockwise as far as it will go. This adjustment, of course, increases the flow through the bottom stratum along the path 3!. bution of air between the paths 29 and 30. It is thus possible to divide the total air flow as desired among the several paths through the horizontal portion of the elbow. The air flow in each path will be substantially uniform across the width thereof since there is nothing to cause a non-uniform distribution laterally. By properly adjusting the dampers, the tendency of the air flowing around the bend in the elbow It to crowd into the bottom of the horizontal portion thereof and to eddy in the top of such portion may be almost entirely'eliminated and the air distributed along a vertical section in the manner most conducive to a thorough mixture of the fuel and air and efiicient combustion thereof. Since large eddies at the bend of the elbow are eliminated by the guide vanes, the air flow forwardly through the port l2 may be made substantially uniform over the entire section thereof. This prevents any marked upward deflection of the combustion gases caused by large eddies formed in an elbow without guide vanes, as previously disclosed.

The invention also lends itself to the correction of a non-uniform distribution of the air in the supply pipe itself. For the purpose of the above explanation, it has been assumed that the air is substantially uniformly distributed over the section of the supply pipe. This is not always the case, because of bends or elbows in the supply line ahead of the burner elbow I4. In such cases, the dampers may be appropriately adjusted to produce substantially uniformly distributed flow Similarly, the damper 33 controls the distrithrough the horizontal portion of the elbow it, should that be desired. In other words, if the volume of flow through the pipe l3 should differ on opposite sides of a central horizontal plane, this may be corrected by means of the dampers to produce a substantially uniform distribution of air through the vertical section of the port I 2.

If it should be desirable, for any reason, to have more or less of the air delivered above or below the fuel jet, this condition may also be produced by properly adjusting the dampers.

It will be apparent from the foregoing description that the invention is characterized by numerous advantages over the apparatus and procedure employed heretofore in the combustion of fuel in furnaces or the like. As already indicated, the desired distribution of the air relative to the fuel can be obtained regardless of the lack of uniform distribution of air in the supply pipe or the tendency of the air to crowd into the outside of the elbow through which it flows into the combustion space. The apparatus involved is relatively simple and inexpensive in construction. It requires little or no maintenance, and is easily adjusted for different conditions. The bafiies or guide vanes do not materially increase the friction drop through the burner, as compared to that occurring in an open elbow.

Although I have illustrated and described but a preferred embodiment and practice of my invention, it will be appreciated that changes in the construction and procedure disclosed may be made within the spirit of the invention and the scope of the appended claims.

I claim:

1. In a burner, an air duct having an elbow therein, with inlet end substantially vertical and with its discharge end substantially horizontal and communicating with a combustion space, a fuel nozzle extending substantially centrally through the discharge end of the elbow, a plurality of fixed horizontal guide vanes extending rearwardly from the discharge end of the elbow to the bend of the elbow, and a movable guide vane hinged to each fixed vane adjacent the rear end thereof and extending into the inlet end of the elbow.

2. Combustion apparatus comprising a burner block having a substantially horizontal port therethrough, means for supplying air to the port including a substantially vertical pipe and an elbow connected thereto and communicating with said port, a fuel nozzle extending through said elbow substantially coaxial with said port, a plurality of horizontal guide vanes spaced apart vertically in the horizontal portion of the elbow and tiltable guide vanes extending upwardly from the rear ends of the horizontal guide vanes.

3. Combustion apparatus as defined by claim 2 characterized by said movable guide vanes being hinged to the substantially horizontal guide vanes.

4. Combustion apparatus as defined by claim 2 characterized by said horizontal vanes having a length several times the distance between them.

FREDERICK S. BLOOM.

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