US2054682A - Boiler - Google Patents

Description

Sept. 15, 1936. Q v F, N055 ET AL 2,054,682

BOILER Filed Deo. 21, 1933 2 Sheets-Sheet l YF-YJENTRS 05CARF-NOSS BY JOI-M M, LCKETT ATTORNEYS Sept. 15, 1936. o. F. Nss ET AL. 2,054,682

BQILER Filed Dec. 21, 1955 l 2 sheets-sheet, 2

INVENTORS 0.5 CAR E N055 BY JOHN LUCKE TT ATTORN EYS Patented Sept. 15, 1936 UNITED STATES PATENT lOFFICE W. Lockett, Oswego,

N. Y., assignors to Fitzgibbons Boiler Company, Inc., New York, N. Y., a corporation of New York Application December 21, 1933, Serial No. 703,396

3 Claims.

The present invention relates to boilers, heat exchangers, and the like and has for an object to provide a boiler of the fire tube type having a high thermal eiciency.

The invention has been developed in connection with the production of an oil burning boiler designed more particularly for the heating of residences, and for the purposes of disclosure of the principles of the invention such a boiler will be more particularly described. It will be underistood, however, that the particular description is illustrative merely and is not intended as defining the limits of the invention.

In boilers generally and especially in oil burn- -ing boilers it is highly desirable that the draft effective in the combustion chamber and in the boiler tubes should be as nearly constant as possible.

In a single pass fire tube boiler the hot gases of combustion rise rapidly to the top of the combustion chamber and in response to chimney draft :pass mainly through relatively few of the upper tubes while the ow through the lower tubes is much less.

This crowding of the combustion gases through ,the tubes of the upper rows creates a very uneven distribution throughout the bank of tubes and results in excessive speed of gases through the upper tubes leaving insufcient time of contact to Agive up all useful heat with the result that the "exit temperature of gases from the upper tubes .is excessively high, often several hundred degrees abovethe temperature vof the slower moving gases issuing from the lower tubes. This Aobviously causes a low thermal efliciency.

Furthermore when combustion is not completed in the combustion chamber before the gases enter the tubes, the chilling of the gases below the ignition temperature by contact with the relatively .cold tube surfaces stops combustion and unburned products are deposited in the form of carbon and tar on the heating surfaces. This soot is one of the best heat insulators known, and when a relatively large part of the total volume of gases rpasses through relatively few of the total number of tubes, an insulating coating of soot is built up rapidly in those few tubes with the result that the greater part of the combustion gases passes through theboiler with very low efficiency.

The inefficiency due to the unequal distribution of the hot gases is the more marked because the temperature of the water in the lower part of a boiler surrounding thev lower rows of tubes is always lower than that of thewater surrounding the upper rows of tubes. Uneven distribution of heat with consequent overheating of the upper tubes also increases the formation of scale thereon.

The present invention aims to equalize the chimney draft and the distribution of the flow of gas through the fire tubes. It aims further to provide a boiler in which the efliciency will be maintained without frequent cleaning by reducing the tendency to deposit soot in the tubes and by reducing the tendency to deposit scale from the water upon the exterior of the tubes.

A further object is to provide an automatic vent operable in the event of explosions to release the pressure.

The invention stabilizes combustion conditions by maintaining an automatically controlled constant draft and provides means for decreasing the ldraft through the upper tubes and for increasing the draft through the lower tubes. This is accomplished in the preferred embodiment illustrated in the drawings by introducing a check valve which is balanced to open automatically when the draft in the chimney exceeds a predeterminedV limit and by providing in the smoke chamber a deflector hood having a somewhat reg stricted cross-sectional area over the outlets of the. uppermost fire tubes and with a gradually increasing cross-sectional area over the middle and lower tubes to Vprovide a substantially uniform draft through all of the tubes.

The uniform draft .and the uniform distribution of the gases throughout the bank of tubes accomplishes several advantageous results. In the rst place the transfer of. heat to the water of the boiler is more complete because of the greater area of heat transferring surface with the consequent reduction of the temperature of the flue gases. In the second place the overheating of the uppermost tubes is eliminated with less deposit of soot within the tubes and less deposit of scale on their outer surfaces. Furthermore, Asuch soot as is deposited is distributed throughout the tubes and the eiiiciency of the boiler ismaintained through a considerably longer period of use and less frequent cleaning isnecessary. There is also less strain on the boiler due to unequal heating and the circulation of Water within the boiler is improved.V

The nature and objects of the invention will be better understood from a'description.- of an illustrative embodiment for the purpose of which description reference should be had to the accompanying drawings forming a part hereof and in which- Y Figure 1-is a diagrammatic partly cross-sec- 55 tional view of a horizontal oil burning fire tube boiler having a deiiector plate and an automatic relief damper constructed in accordance with the invention,

Fig. 2 is a rear View of the same,

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 1,

Fig. 4 is a rear view of the boiler with the rear door open to show the parts within,

Fig. 5 is a sectional view taken on the line 5--5 of Fig. 2, and

Fig. 6 is a detail sectional View of the rear door latch.

In the structure shown for purposes of illustration the boiler 5 comprises a combustion chamber 6 and fire tubes I extending horizontally from the combustion chamber to the smoke chamber 8, from the top of which a pipe 9 leads to the chimney. In accordance with the inven tion, means is provided for reducing the draft through the uppermost of the fire tubes in order to compensate for the tendency of the hot gases in the combustion chamber to rise to and pass through the uppermost tubes. By this means an even distribution of the gases through the tubes is obtained. In the particular arrangement shown a deflector hood III is suitably supported within the smoke chamber to form a substantially smoke tight seal along its sides and across its upper edge against the tube plate II into which the ends of the tubes are secured. The hood is made in two sections I2, I3, one slightly overlapping the other, suspended on hooks I4, I5 in the rear wall of the boiler, each section being small enough for removal through the rear door I6. The handles I'I, I8 facilitate removal and replacement.

The cross-sectional area, of the hood is relatively small at the top and increases downwardly in proportion such as to provide a substantially equal draft throughout the whole range of the bank of tubes. Ordinarily the hood may be correctly designed for a particular boiler so that it is unnecessary to make the hood of adjustable cross-section, as for example by pivoting the rear wall thereof to move inwardly. With this arrangement the draft from the lowermost tubes is substantially unimpeded by the deflector hood but that through the upper tubes is progressively more and more checked toward the top, thus compensating for the thermal effect whereby the hottest gases pass readily to the top of the combustion chamber and there create a draft inducing pressure. The form of hood shown in which the sides are closed is preferred to a mere fiat plate because of the tendency in the case of the flat plate for the` draft to be unduly increased through the tubes close to the outer edges of the plates. Obviously a single plate, flat or curved, could be designed to materially improve the draft condition often found in boilers of the horizontal fire tube type and if extended suiiiciently toward the sides of the smoke chamber would give effective results.

The deflector hood is preferably placed sunlciently close to the outlets of the re tubes so that, especially opposite the uppermost tubes, it substantially impedes the draft therethrough, although obviously there should be ample space for the passage of the gases.

The rear door of the smoke chamber is hinged at I 9 and latched at20. In order to permit release of pressure in the event of an explosion, as may happen when the oil burner is lighted, the latch stud 2| carries a spring 22 which holds the latch normally in inner securing position but permits movement outward in the event of excess pressure within the smoke box.

Uniformity of the effective draft at the combustion chamber is insured by the balanced check valve mounted on ball bearings 26 in the door I6. The pivot axis is slightly off center whereby the larger area receives the air pressure of any back draft and causes immediate closing and is immediately opened by a suction greater than a predetermined amount. In order to hold the valve closed when the draft is within the predetermined limit a weight 2l is carried by the valve and projects inwardly therefrom. This weight may be adjustable as by making the weight to consist of a stud with lighter or heavier nuts but usually this is not necessary. The valve is made of cast aluminum for sensitiveness and furthermore the aluminum valve with the iron or steel mounting provides a relatively noiseless combination.

The doorv I6 is formedwith a shield 30 projecting into the path of the hotv combustion gases and having for part of its extent a lip 3I in order to deiiect the gases from the check valve25. Otherwise the gases escape through the valve when it opens in response to increased chimney draft. On one side the lip 3l is of reduced yWidth to permit the check valve to open through quite a large arc, as indicated at 32. Closing movement of the check valve is limited by a lug 33 engaging the door.

A hole 35 is provided in the door I6 below the shield 30 to permit introduction of a thermostat to the point where the stack gases are hottest. Some engineers prefer to use such a thermostat as a safety device to shut ofi the oil burner if and when the gases get above a predetermined temperature.

It will be understood that the foregoing. description is not intended as defining the limits of the invention for the principles involved may be variously applied and numerous embodiments of the invention may be developed without departing from the spirit of the appended claims.

We claim:

1. A fire tube boiler having, in combination, a combustion chamber, a smoke chamber, a bank of horizontal fire tubes leading from the combustion chamber to the smoke chamber and a defiector hood in the smoke chamber over the outlets of said fire tubes to deflect the gases downwardly and outwardly and to equalize the draft through the tubes, a balanced damper in the wall of the smoke chamber, and a shield for defiecting away from the damper the stream of gases issuing from below the defiector.

2. A re tube boiler having, in combination,

la combustion chamber, a smoke chamber, a bank of horizontal fire tubes leading from the combustion chamber to the smoke chamber, a door opening into the smoke chamber in line with the fire tubes, a removable deiiector hood in the smoke chamber over the outlets of the fire tubes Yto equalize the draft through said tubes and arranged to deflect the gases downwardly and outwardly toward the door, a check damper consisting of a plate kbalanced on an eccentric diagonal pivot'to open when the draft within the smoke chamber exceeds a predetermined limit, and a shield between the deflector hood and the check damper positioned to deflect the gases away from the checkV damper, substantially as described.

3, A fire tube boiler having, in combination, a.

combustion chamber, a smoke chamber, a bank of horizontal fire tubes leading from the combustion chamber to the smoke chamber, a door opening into the smoke chamber in line with the re tubes, a two part delector hood in the smoke chamber over the outlets of the fire tubes to equalize the draft through said tubes and arranged to deflect the gases downwardly, hooks in the smoke chamber on which the deector 10 hood parts are removably suspended, a check damper in the door consisting of a plate balanced on an eccentric diagonal pivot to open when the draft within the smoke chamber exceeds a. predetermined limit, and a shield secured to the door between the deector hood and the check damper positioned to deflect the gases away from the check damper, substantially as described.

OSCAR F. NOSS.

JOHN W. LOCKETT.

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