US3362454A - Air inductors for oil burners - Google Patents

Description

Jan. 9, 1968 M. BELZER AIR INDUCTORS FOR OIL BURNERS Filed Sept. 6, 1966 INVENTOR MILTON BELZER AT ORNEY United States Patent 3,362,454 AIR INDUCTORS FOR OIL BURNERS Milton Belzer, 5535 Columbia Pike,

' Arlington, Va. 22207 Filed Sept. 6, 1966, Ser. No. 590,133 7 Claims. (Cl. 158-4) ABSTRACT OF THE DISCLOSURE This document describes an inductor for conducting secondary air from the draft opening of a boiler to the nozzle of an oil burner to insure better combustion of fuel. The inductor has a configuration such as to fit with existing boilers and carry the seoon'dary air to the ignition point of the fuel without unduly increasing the velocity of the burning gases.

This is a continuation-impart of my copending application, Ser. No. 406,324, filed Oct. 26, 1964, now abandoned.

This invention is concerned with improving the efiiciency of oil burners, particularly those using heavy fuel oil, and provides a novel air inductor by which secondary air can be brought to the cone of the oil burner to improve combustionat the ignition point of the fuel oil.

It is well-known that hydrocarbon oils have an ignition temperature which is related to the average molecular weight of the oil, heavier fuel, that is, those of greater average molecular weight, requiring a higher temperature for ignition. It also is well-known that the initial combustion of heavy fuel oils involves not only oxidation of hydrocarbons but also cracking, that is, splitting of the larger molecules to smaller molecules, often with the production of solid carbonaceous material which forms smoke and/or soot. The smaller hydrocarbon molecules can burn at a lower temperature, but the solid carbonaceous material requires a high temperature for ignition. In a conventional burner for heavy oil fuel, such as is found in heating plants in apartment houses, institutions, etc., the heavy oil is atomized, that is, formed into droplets, within a rapidly moving air stream. The resulting oil and air mixture is ignited at the nozzle of the burner and the flame produced thereby is carried by the rapidly moving air stream into the fire box which is adjacent to, usually below, a heat exchange means, such as boiler tubes.

It will be readily recognized that there are inherent limitations on the amount of air, called primary air, which can be introduced to the nozzle with the oil. For exam'ple, good ignition requires that the mixture pass the ignition point in a confined stream and at a velocity slow enough to bring the mixture to combustion temperature. The art has attempted to supply auxiliary air to the fire-box by providing most oil burner installations with a draft opening at or near the bottom of the firebox. The secondary air introduced thereby can serve to complete the ignition of some lower-molecular weight hydrocarbons found in the fire box downstream from the oil burner nozzle or cone, where the temperature is lower than at the main ignition point, and also can serve to ventilate the fire -box, that is, to carry out combustion products and incompletely burned fuel, including soot. However, such secondary air from the conventional draft opening fails to provide combustion of those unreacted or incompletely oxidized hydrocarbons or solid carbonaceous materials which require a high ignition temperature. The apparatus of this invention provides for improved combustion of such hydrocarbons by bringing the secondary air directly to the main ignition point and directing it into the hydrocarbon stream.

While the art has provided many devices for the introduction of secondary air to the firebox, it is not known that any of them introduces such an directly to the ignition point or cone of the oil burner. Rather, such introduction is usually made downstream of the ignition point, where the temperature may already be too low for full ignition of all fuel components. Further, such devices often must be part of the original equipment of the furnace installation or else require substantial modification of an existing fire-box and oil-burner heat-ing plant, sometimes amounting to almost complete dismantling of the plant, thus m alcing the cost of installation prohibitive in many cases. The device of this invention, however, may be readily slipped into most existing installations without substantial modification of the fire box or the need to remove the oil burner. The device is essentially fiat and is placed inside the fire box, lying vertically along the front wall of the fire-box. The original insulation of the fire box is preserved and any heat absorbed by the device is reradiated into the fire-box, thus minimizing any heat losses.

This invention comprises an elongated air channel means which can communicate with the inside of the draft opening of the conventional fire-box and extend upwardly to the-vicinity of the oil-burner entry into the firebox. The channel means is surmounted by a circular air crown which is disposed about the cone of the oil burner. Generally the crown flares outwardly downstream of the oil burner cone, allowing for expansion of the gas stream due to combustion without causing an undue increase in velocity of this stream. An air director is mounted in the air crown to deflect the secondary air more completely and accurately into the main gas stream.

The air channel means generally is of metal and is therefore a good conductor of heat, and has a width at its bottom suflicien-t to cover the draft opening of the fire box. It generally will taper upwardly and at its upper end have a width equal to the diameter of the circular air crown. The metallic nature of the air channel provides for some heating of the secondary air by heatexchange between the draft opening and the ignition point, thus serving to avoid undue lowering of the temperature at the point of ignition. Also, the combination of the flaring air crown with the burner nozzle appears to create a suction effect at the point where the air channel empties into the air crown, serving to suck in a greater amount of secondary air than would ordinarily be obtained from the draft opening. The air-channel means may provide in itself all four sides of the channel, but advantageously the inside, usually insulated, wall of the fire-box itself between the draft opening and the oilburner entry can serve as the fourth side of the channel.

The invention will be better understood by reference to the accompanying drawing, which is to be considered illustrative only and not limiting, and in which:

FIGURE 1 is a perspective view of the device of the invention;

FIGURE 2 is a front elevation, showing the device installed in a fire-box with an oil burner; and

FIGURE 3 is a vertical section taken along the line 3--3 of FIGURE 2.

As can be seen from the drawing, the air channel member 1 is a relatively flat, vertically elongated, trough having at least front and side portions. The width of the channel member near its bottom is sufiicient to cover the draft opening 2 in the front wall B of a conventional fire-box. The channel extends upwardly to the vicinity of the oil-burner nozzle 4, its width usually tapering as it rises. As is conventional, the oil-burner nozzle 4 projects slightly into the fire-box through the wall B and as can be seen, the channel member 1 conducts the secondary air to locations both slightly upstream and slight- 1y downstream of the burner nozzle, assuring the presence of this secondary air at the nozzle tip which defines the ignition point of the oil. Also, as can be seen, the inside front wall of the fire-box can serve as the fourth side of the air channel.

The circular air crown 3 is provided at the top of the air channel, and surrounds the nozzle, preferably axially. Also, as mentioned, this crown preferably flares outwardly downstream of the burner nozzle. The stationary air director 5 is mounted in the crown 3, preferably at its top, and serves to deflect the secondary air into the main gas stream rather than allow it to continue in a circular path surrounding this gas stream.

It can thus readily be seen that this invention provides a device which is readily installable in and removable from a conventional fire-box without any significant alteration of the original installation. The air crown is usually sufficient to fit around the nozzle of any conventional oil burner and the height of the channel may be adjusted for any distance of the burner entry from the floor of the fire-box. Although highly suitable for use in existing oil-burner installations as mentioned, when fastened into the fire-box by any convenient means, the device of this invention may comprise part of the original equipment of the plant.

By bringing the secondary air directly to the point of ignition, the device of this invention improves combustion and thus minimizes smoke and stack temperature While increasing the heating efiiciency of a given quantity of fuel.

What is claimed is:

1. An air inductor for insertion into a boiler without significant alteration of the boiler which comprises the combination of an air channel member communicating at its lower end with the inside of the draft opening of the boiler, and having a width near its bottom sufficient to cover said draft opening and a circular air crown, supported on the upper end of said channel and disposed about the nozzle of an oil burner within said boiler, said crown flaring outwardly downstream of the oilburner nozzle and adapted to direct secondary air supplied through said channel and said crown, into the atomized oil at ignition point.

2. An air inductor according to claim 1 in which the air channel member is of heat-conducting metal.

3. An air inductor according to claim 1 in which the said air channel member tapers from a width near its bottom suflicient to cover said draft opening to a width at its top about equal to the diameter of the air-crown.

4. An air inductor according to claim 1 in which the said channel member is adjacent to and extends along the inside front wall of the boiler.

5. An air inductor according to claim 1 in which the wall forms a side of said channel member.

6. An air inductor according to claim 4 in which the circular air crown is about coaxial with the oil-burner nozzle.

7. An air inductor according to claim 1 in which the air crown is provided with an air director mounted therein.

7 References Cited UNITED STATES PATENTS 325,376 9/1895 Baker 158-4 2,334,617 11/1943 Fisher 1581.5 3,037,550 6/1962 Uschold 158-1.5

FREDERICK L. MATTESON, JR., Primary Examiner.

E. G. FAVORS, Assistant Examiner.

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