US2112063A - Peep sight for furnaces - Google Patents

Description

March 22, 1938. .1t BUZARD y 2,112,063

PEEP SIGHT FOR FURNACES Filed Aug. 7. 1956 Patented Mar. 22, 1938 lm'raN'rl OFFICE PEEP SIGHT FOR FURNACES John Blizard, Garden City, N. Y., assignor to Foster Wheeler Corporation, New York, N. Y., a corporation of New York Application August 7, 1936, Serial No. 94,751

is ci. (ci. 126-190) My invention relates to furnaces, and an improved means for permitting observation of internal furnace conditions, and the action of the vburning gases on the refractory walls of a high temperature furnace chamber,` and on any .tubes or other devices disposed therein.

The invention is particularly applicable to furnaces which are wholly or partially surrounded by an air duct or air chamber, in which the pressure is higher than that existing in the fur- I nace, and in which an aperture or peephole of special design, comprising a sight tube and nozzle member, opens to the atmosphere in the boiler room or ring isle and extends inwardly `therefrom through the air duct and refractory' furnace Wall to the furnace, whereby a clear vision may be had into the furnace chamber whenever desired, without discomfort or injury and without the use of any interposed transparent material such as glass or mica.

In operation, such devices depend on the pressure differential existing between the air duct and the furnace to create a flow of air from the air duct of sumcientA momentum to oppose any flow of gases from the furnace, and further depend upon a Venturi shaped nozzle assembly and diffuser to force the air from the air duct through the peephole into the furnace at the desired velocity. Apparatus of the kind described is broad-` ly disclosed in, and forms the subject matter of the application of Hugh E. Carleton, Serial No. 89,287, filed July 7, 2,105,309, granted January 11, 1938.

The present invention constitutes an improvement thereon, and includes a damper for shutting .olf the ow of air from the air duct to the furnace during the periods when visual access to the furnace is not desired, which is highly desirable from the standpoint of combustion. Also, the arrangement is such that the opening to the peephole in the boiler room or ring isle cannot be opened for'use until after the damper has been moved to the fully open position, thus first establishing a ow of air duct into the furnace and preventing possible injury to the operating personnel by an outward blast of furnace gases or preheated air, which would be'the result if the order of the operation were reversed, due to the relatively high pressure existing in the air.

l duct and furnace chamber.

1936,` now Patent No.v

Fig. 1 is a vertical sectional view of `a preferred form of apparatus embodying the invention, taken substantially on line I--I 'of Fig. 2;

Fig.A 2 is an elevation of the outer end of the apparatus, as shown in Fig. 1; and 5 Fig. 3 is a transverse sectional view of the apparatus taken on line l:i3- 3 of Fig. 1.

Like reference characters refer to like parts throughout the several views..

Referring to the drawing, particularly Fig. l, 10 reference character l0 designates the inner refractory lining of a furnace chamber having an outer lining of suitable refractory material, while I2 and I2' indicate the inner metallic casing walls of an air duct or chamber I3 which may l5 entirely surround the furnace or may be disposed on and exteriorly of, one or more walls thereof. 'I'he outer wall is formed by heat insulating material designated I4 and outer metallic casing I5. Suitable means are provided to maintain a pres- 20 sure in the air chamber which is higher `than the pressure in the furnace, or that yof the surround- 4 ing atmosphere.

The. peephole arrangement selected for illustration, includes a tapered sight tube I6 having an inner end portion I6' and a laterally extending annular ange at its outer end. The inner end of the sight tube extends into the throat or reduced portion 25 of a nozzle member 23 which is secured by bolts 24 and 24 to casing I2, and-30 forms in combination with an enlarged furnace opening 26, a Venturi shaped nozzle assembly and diffuser which is arranged and adapted to provide when the peephole is in use, the desired volume and velocity of air ow therethrough from the 35 air chamber to the furnace, and at the same time to permit a wide range of vision within the furnace when the sight tube cover plate I'I is removed. If desired, the nozzle member 23 may be arranged to extend entirely through the fur- 40 nace wall, in which event a flared aperture in the furnace wall may not be necessary. Cover plate I'I, which opens to the boiler room or ring isle, is secured to an intermediate portion of a latch I8 by a pin I9, and the latch is hinged at 45 one end by pin 20 on spaced studs 20' extending from the annular ange on the sight tube I6. 'I'he other end of the latch I8 is provided with a slot I8 which receives a swinging bolt 2| secured to'said annular flange. As shown in the drawing, 5 0 swinging bolt 2| also passes through a slot 3|' in a' lever arm 3| forming. a part of the damper means hereinafter described, and both the lever arm and the cover plate I1 are secured in closed position by a wing nut 2| `threaded on the bolt 2|. 55

'I'he lsight tube I8 is supported on the outer wall of the air chamber by means of the annular flange thereon and by bolts 22 that pass through the ange and the outer wall.

Reference character 21 designates a thin, generally triangular or segmental shaped metal disc, or damper, fixed to squareddlportion 84 of an operating shaft 28 by washers 35 and nuts Il and 31. The cylindrical inner end 20 of shaft 28 is supported by bearing block 38 and rotates therein. while the outer end Iii passes through the annular flanged portion of sight tube IB and is supported thereby for rotation in gland 40. Air leakage through the gland is prevented by packing 39. The lever arm 3i is iixed to operating shaft 28 by cap screw 33 and is operated by handle 32. The damper 21 is received by a narrow transverse slot or groove 42 disposed in the nozzle member 23 inwardly of the inner end I6' of sight tube I 6, and is adapted for a limited rotary movement therein when operated by shaft 28 and lever arm 3|. An orifice 4| in damper 21 corresponds substantially in diameter to the diameter of the throat of the nozzle member. The arrangement is such that by rotating the damper through a relatively small arc or range, transversely to the axis of the nozzle member, either the ow of air to the furnace can be entirely cut off, or the orifice 4I can be brought in axial alignment or register with the throat of the nozzle member, and a flow of air established from the air duct to the furnace. When .in the fully open position, as indicated by position A of the damper in Fig. 2 of the drawing, stop nut 43 on damper 21 is in contact with the outer wall of the nozzle member, thereby preventing movement of the damper beyond fully open position.

As illustrated in the drawing, the damper is closed, and all flow from the air duct to the fur-f nace is cut oil'; both the lever arm 3i and cover plate I1 of the sight tube are securely held in closed position by, latch I 8, swinging bolt 2| and wing nut 2| threaded thereon. ,When it is desired to use the peephole, wing nut 2l' is loosened and the lever arm 3| is moved upwardly to the right, as shown by dot and dash lines in Fig. 2, until further movement is prevented by the stop nut 43, in which position the lever will be clear of the cover plate. 'I'he bolt 2| is then swung free of the latch i8, and the latch and the cover plate are swung downwardly away from the outer end of the sight tube, thus permitting a clear vision through the peephole to the furnace without discomfort or risk of injury due to a sudden blast of hot air or furnace gases. When it is no plonger desired to use the peephole, the damper is moved to closed position and the several parts associated therewith are returned to the positions shown in the drawing.

Itis to be understood that changes may be made in the form and structure of the apparatus herein described and disclosed, without departing from the principles of the invention which is not to be limited except by the scope of the appended claims.

What I claim is:

1. In a furnace having an air chamber outside at least one wall thereof, means for observing combustion and internal furnace conditions comprising a sight tube, a nozzle member arranged to conduct air from the air chamber to the furnace and cooperating with the sight tube in such manner as to permit observation of the furnace interior through the sight tube and nozzlelmember, and a shut-off damper for the nozzle member movable transversely of the axis of the nozzle member.

2. In a furnace wholly or partially surrounded by an air chamber, a peephole assembly comprising a nozzle member extending between the air chamber and the furnace, a sight tube extending through the wall of the air chamber inwardly to the throat of the nozzle member, and a damper for the nozzle member disposed inwardly of the furnace end of said sight tube for controlling the iiow of air through the nozzle member from said air chamber to the furnace.

3. In a furnace having an air chamber outside at least one wall thereof, means for observing combustion and internal furnace conditions therein, comprising a nozzle member for conducting air from the air chamber to the furnace. a sight tube extending through the outer wall of the air chamber and cooperating with lthe nozzle member, a cover for the outer end of the sight tube, and a damper for the nozzle member operable independently of the sight tube and its cover.

4. In a furnace having an air chamber outside at least one wail thereof, means for observing combustion and internal furnace conditions therein, comprising a 'nozzle member Yfor conducting air from the airchamber to the furnace, a sight tube extending through the outer wall of the air chamber and cooperating with the nozzle member, a cover for the outer end of the sight tube, a damper for the nozzle member, and means independent of the sight tube and its cover "or operating the damper, said damper operating means being disposed so as to prevent movement of the sight tube cover to open pojtun when the damper is in closed position.

5. In a furnace having an air chamber outside at least one wall thereof, means for observing combustion and internal furnace conditions therein, comprising a nozzle member for conducting air from the air chamber to the furnace, a sight tube extending through the outer wall of the air chamber and cooperating with the nozzle member, a cover for the outer end of the sight tube, a damper for the nozzle member, means independent of the sight tube and its cover for operating the. damper, and single means for v securing the damper and said cover in closed position.

end of said sight tube, and a damper for saidv nozzle member movable transversely of the axis of said nozzle member for controlling the flow of air therethrough, and common means for securing said cover plate and said damper in closed position.

'1. In a furnace having an air chamber outside at least one wall thereof, a peephole for observing internal furnace conditions comprising a nozzle member arranged to conduct air from the air chamber to the furnace, a sight tube in axial augment with the nozzle member, a cover plate for the outer end of said sight tube, a damper for said nozzle member disposed inwardly of the furnace end of said sight tube, and common means for securing said cover plate and damper in closed position.

8. In a furnace having an air chamber outside anaoea at least one wall thereof, a peephole for observing internal furnace conditions comprising a nozzle member arrangedy to conduct air from the air chamber to the furnace, a sight tuberextending through the wall of the `air chamber to the throat of the nozzle member, a cover plate for closing said sight tube, a damper for said nozzle member movable transversely of the axis thereof for controlling the flow of air therethrough, a lever for opening and closing said damper, and common means for securing both the damper and cover plate in closed position, the arrangement v being such as to prevent the opening of said cover `plate when said damper is closed. l

9. In a furnace having an air chamber outside y at least one wall thereof, a peephole for observing internal furnace conditions comprising a nozzle member arranged to conduct air from the air chamber to the furnace, a sight tube extending through the wall of the air chamber to the throat of the nozzle member, a cover plate for closing said sight tube, a damper for said nozzle member, an orice in the damper, and means for rotating said damper transversely of the axis of said nozzle member whereby the orice is moved into or out of alignment with the nozzle member, thereby permitting or preventingilow of air through the nozzle member from said air chamber to the furnace. l

10. In a furnace having an air chamber outside at least one wall thereof, a peephole for observing internal furnace conditions comprising ya nozzle memberarranged to conduct air from the air chamber to the furnace, a sight tube extending through the wall of the air chamber to the throat of the nozzle member, a cover plate for closing the sight tube, a damper for said nozzle member disposed inwardly of the furnace end of said sight tube. an orifice in the damper having a flow area substantially equal to the ilow area of the-throat of the nozzle member, means for rotating said damper through a limited arc to open or close said nozzle member, and common means for securing the cover plate and damper in closed position, said means for rotating the damper being arranged and disposed so as to prevent the opening of said cover plate before said damper has been rotated to the fully open position.

11. In a furnace having an air chamber outside at least one wall thereof, a peephole for observing internal furnace conditions comprising a nozzle member arranged to conduct air from the air chamber to the furnace. a sight tube extending through the wall of the air chamber to the throat of said nozzle member, a cover plate for closing said sight tube, a damper for the nozzle member disposed inwardly of the furnace end of said sight tube, a shaft extending through the wall of the air chamber and operably connected to the damper, an operating lever xed to the shaft at its outer end and arranged lto overlap said cover4 plate, and common means for securingthe lever and cover plate in closed position, the arrangement being such that said cover plate cannot be removed from said sight tube until the damper is moved to a position inv which the nozzle member is open.

l2. In a furnace having an air duct outside at least one wall thereof, means for observing combustion and internal furnace conditions comprising a nozzle in a wall of the furnace, a sight tube extending through the wall of the air duct and having its inner end so disposed with respect to the nozzle that uid ow through the latter causes air flow inwardly through the tube, and a shut off damper for the nozzle member movable transversely of the axis of the nozzle member.

13. In a furnace having an air duct outside at least one wall thereof, means for observing combustion and internal furnace conditions comprising a nozzle in a wall of the furnace, a sight tube

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