US2701999A

US2701999A - Draft equalizing stack head

Info

Publication number: US2701999A
Application number: US313568A
Authority: US
Inventors: William O Moran
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-10-07
Filing date: 1952-10-07
Publication date: 1955-02-15
Anticipated expiration: 1972-02-15

Description

Feb. 15, 195s i w; Q MORAN y 2,101,999

DRAFT EQUALIZING STACK HEAD 2 sheets-sheet 1 @U2/19 /7 li Filed Oct. 7, 1952 woo www

" william amm Feb. 15, 1955 w. o. MoRAN 2,701,999

DRAFT EQUALIZING STACK HEAD Filed Oct. 7, 1952 I I 2 Sheets-Sheet 2 Siwa/YM /Vllam 0. Moran im 5M M 77;@

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Un'ited States Patent() 1mm EoUALiziNG sucx imap william o. Mom, misa, om.

Applicatie.. ociober 1, 1952, semi No. 313,568

s claims. (ci. 9s-ss) This invention relates to improvements in the structure of the stack head of chimneys and exhaust stacks to provide for equalizng the draft therein regardless of outside wind conditions. This invention is a continuation-inpart of mycopending application Serial No. 54,451 filed October 14, 1948, now U. S. Patent 2,655,833, issued October 27, 1953, said copending application being a continuation of applicants application Serial No. 689,231, filed August 8, 1946, now abandoned.

It`is the object of my invention to provide a stack head structure that will eliminate draft fluctuationcaused by wind direction and force changes thus providing a controlled draft resulting in increased eticiency of the boiler or heater which discharges into an exhaust stack or chimney having a stack head structure according to my invention. l

A further object of my invention is to provide a head structure in a chimney or exhaust stack that will keep the draft constant and hold the fre in the fire box of the boiler or furnace connected thereto.

Another object of my invention is to provide a chunney or exhaust stack for a boiler or furnace which is constructed with its top end imperforate but having the adjacent vertical side walls there below pierced with a plurality of orifices or ports preferably in uniform spaced relationships and having suicient area to permit free movlment of exhaust gases from the chimney or exhaust stac Another object of my invention is to provide a cap for telescopic mounting into or onto the top end of a chimney or exhaust stack of a boiler or furnace wherein the cap is constructed with an imperforate top end but has the adjacent vertical side walls there below pierced with a plurality of orifices or ports preferably in uniform spaced relationships and having sufficient area to permit free movement of exhaust gases from the chimney or exhaust stack.

A still further object of my invention is to provide a heating unit with an equalizng stack head in order to maintain an equalized or uniform draft, and prevent downdraft, regardless ofthe direction and amount of wind pressure that may occur at the stack head.

Another object of my invention is to provide a ventilator for any type of structure where ventilation is needed but where excessive ventilation is undesirable, such as would be caused by high winds blowing across the conventional type of ventilator. This type of ventilation is especially desirable in carbon black plants, paint rooms, battery rooms, and many other places where a constant steady draft is required.

These draft equalizng stack heads, when used as ventilators can be installed on trucks, planes, trains, or ships, as the speed of the conveyance, plus the speed of the wind, will not change the draft through these stack heads.

Other objects and advantages of the invention will be evidient from the following detailed description read in conjunction with the accompanying drawings.

ln a chimney or stack head having the usual end opening of area equal to the cross sectional area of the end of the stack, increased wind pressure from any direction blowing over the open top end of the stack causes a suction upward in the stack and pulls lthe fire from the fire box. This action causes a demand for more fuel and the draft is somewhat proportional to the wind pressure. However, according to my invention with a chimney head provided with a closed top with adjacent walls there be- 2,701,999 Patented Feb. 15, 1955 ICC low havin spaced holes therethrough of suticient s rea to permit re movement of exhaust gases from the chimney or exhaust stack, there is created a uniform draft in the stack regardless of wind velocity or direction. It is thought that the vacuum-created in such a construction by the action of the wind on the down wind side of the stack is offset by wind blowing from the up wind side of the stack that passes through the apertures in the stack supplying air to counteract the vacuum created on the opposite side of the stack. This action of the windpassing through the apertures on the Windward side of the stack offsets the vacuum normally created on the leeward or down wind side of the stack and this action serves to create a uniform draft in the stack and fire box regardless of the wind force or direction.

When the wind begins to blow against the stack head, it shortens the flow-of the stack gases on the upstream, or Windward, side of the stack, but it lengthens the ow of stack gases on the downstream side of the stack. As the wind increases in velocity across the stack head, the flow of stack gases on the upstream side continues to shorten, and the flow of stack gases on the downstream side continues to lengthen, until such time as the wind pressure and the pressure 'of the stack gases are equal. At this point, the openings in the upstream side are effectively sealed off because with wind pressure on the outside of the stack being equal to the pressure of the stack gases on the inside of the stack, no wind can blow into the stack, nor can any of the stack gases escape from the stackon the upstream side. When the wind pressure exceeds the stack pressure, the wind blows through the openings on the upstream side, which supplies the excess demand created by the lessening of pressure, or by the vacuum created on the downstream side, which permits a faster flow of the stack gases through the openings, in the downstream side of the stack.

It has been proven by many extensive tests that the velocity of the wind blowing through the stack head does not change the velocity or the amount of stack gases pulled through the fire box of the boiler; thus, maintaining still day efiiciency of heating equipment regardless of the velocity of the wind.

My invention may be used on exhaust stacks of heaters for meter houses which are frequently erected in isolated and exposed places where they may be subjected to winds which blow from every direction of the compass and over a large range of wind velocities. A heater for such an exposed meter house must be capable of functioning continually without being influenced by variations in wind directions and velocity, and particularly without being extinguished by sudden changes in direction of the Wind and its velocity.

For a more complete understanding of the nature and scope of my invention reference may be had to the accompanying drawings in which:

Fig. 1 is a perspective view according to my invention;

Fig. 2 is a vertical cross sectional view along lines 2 2 of Fig. l but showing the open bottom end of the cap teleskcopically received over the open end of an exhaust stac Fig.- 3 is a cross sectional view showing the cross section of the cap as viewed along line 3 3 in Fig. 4;

Fig. 4 is a schematic drawing of a cross section of a of a draft equalizer cap heatei having a draft equalizer stack head or cap installed on the exhaust stack according to my invention;

Fig. 5 is a perspective view looking upward from a position adjacent the bottom end showing a modified form of draft equalizng cap or stack head mounted within the top of a top fragmentary end of a stack;

Fig. 6 is a cross sectional view of the modified form taken on line 6 6 of Fig. 5; and

Fig. 7 is a cross sectional view taken along lines 7 7 of Fig. 6 of the modified form of cap or stack head.

Throughout the various views in the drawing like reference numerals refer in similar parts.

In Fig. 4 a typical heater, furnace, boiler or the like is indicated at 10 having a fire box l1 provided with a burner 12 over which is positioned a horizontal baille 13 providing an exhaust chamber 14 having a vertical exhaust stack or chimney l attached thereto on the upper portion of the heater or furnace.

I mounted on the upper end of the exhaust stack or chimney 15 a draft equalizing head or cap generally indicated at 16.

The cap 16 in the embodiment here illustrated is of elongated cylindrical shape having a vertical wall 17, an open bottom end 18 telescopicallv received over the end 15' of the stack 15, and an imperforate top end 19. The wall 17 is pierced with a plurality of apertures 20 extending therethrough, preferably equally spaced and having suicient area to permit free movement of exhaust gases from the chimney or exhaust stack. These apertures 20 are positioned all around the whole wall area 17. At the lower end 19' of the cap 16 adiacent the open bottom 18 there may be positioned a plurality of equally spaced threaded apertures 22 which receive threaded tap screws 23 to secure the cap 19 in the upper end 15 of the exhaust stack 15.

While l have here shown the apertures 20 as being t circular they may be of any configuration, circular apertures being here shown and used as they are more easily provided.

Tn Figures l and 2 it will Abe noted that thereare seven horizontal rows of apertures 20 spaced substantiallv at a uniform distance apart along the elongated vertical wall 17 of cap 16. There are an even number of apertures in each row, namelv. twelve apertures having a uniform `eclual area. The apertures 20 are disposed in uniformly spaced relationship throughout the whole circumference of the cap 16. Each of the apertures 20 is disposed in each horizontal row so that each aperture has an oppositelv disposed aperture in horizontal alignment therewith. This same arrangement of apertures applies to the structure shown in Figures 5, 6 and 7. except that each horizontal row in the cap or stack head 29 has an even number of -fourteen apertures 30.

The exhaust stack 15 may equally as well be a bricked uo chimney and .in such a case I carry out my invention bv laving up the head of the chimney with an apertured wall having the total aperture area sufficient to permit the free movement of exhaust gases from the tue or chimnev. ln laying up a brick chimney, I would provide an imoerforate top end 19 as I have in the cap 16 here illustrated.

I have shown in Fig. 2 arrows P to represent the wind blowing against an area at the left hand portion of the cap 16 while at the opposite area. arrows V represent a vacuum created about the opposite area of the cap. The arrows designated S within the exhaust stack 15 represent the suction existing in the ue of the exhaust stack or chimnev. This suction remains stable even though the pressure of the wind at P may increase or decrease and the corresponding vacuum represented by the arrows V mav increase or decrease. The wind is permitted to pass through the apertures 20 in the area of the blowing wind P and it is thought to offset the vacuum created at V at the opposite area of the stack head or cap, thereby not disturbing the suction within the exhaust ue.

In a beater such as is used in meter houses in the oil fields which have a 3" diameter stack of 7 feet in length, I have installed a 3" cap and made certain tests. The pressure of the gaseous fuel supplied to the burner in the fire box was 6% ounces open pressure. Compressedair was blown across the top of the heater stack without having an eoualizing cap installed and when the pressure of the compressed air in a 1A" blowing nozzle reached 20 pounds per square inch gauge pressure. the flame in the fire box was extinguished thereby. This condition of flame extinguishment existed when either butane or natural gas was used.

A draft eaualizing stack head according to my invention was then installed on the exhaust stack of the heater and further tests were conducted after the burner was ignited in the lire box of the heater. The compressed air nozzle discharge was directed against the perforated cap to simulate the blowing wind and the pressure was raised in the compressed air line to 550 pounds per square inch gauge pressure. the highest available, and the ame at the burner was not blown out.

Figures 5, 6 and 7 depict a modified form of cap or stack head generally indicated at 29 which is adapted for telescopic reception within a stack 15. The cap 29 1s of cylindrical shape and is provided with a plurality of relatively small spaced apertures or orifices 30 in the wall 31 thereof. The total area of the orices 30 may be ter than the cross-sectional area of the stack on which the head or cap is mounted. The same theory of operation as explained for the stack head 16, as illustrated in Figure 2, applies'as respects stack head 29.

The cap or stack head 29 is provided with an annular imperforate base 32 which is attached as by welding to the top end of a cylindrical thimble 33 adapted to be received by a telescopic slip tit in the topend of the stack or chimney 15 such that the imperforate annular base 31 rests on the top end l5 of the stack 15. The upper end of the stack head or ca 29 is closed off' by an imperforate top plate 34 attac ed as by welding. Imperforate top plate 34 is shoQwn as extending as an annular lip 34' beyond the cylindrical wall 31.

The cap or stack head 29 is held in place on the top end of the stack 15 by its own weight, however, if desired securing means such as tap screws (not shown) may be inserted through suitable apertures (not shown) formed in the stack 15 and received in threaded apertures (not shown) in the thimble portion 33 of the cap 29.

Draft equalizing stack heads according to my invention are useful in increasing the elciency of operation in all types of furnace and boiler plant installations. As an example of increased efciency such stack-heads were installed on a gasoline plant having nine oil field type boilers. Prior to the installation of the draft equalizer stack heads or caps, the fuel consumption of these boilers was at the rate of 1550 cu. ft. per rated boiler horse power per day under normal windage conditions. After the installation of the draft equalizing stack heads the fuel consumption decrease from the 1550 cu. ft. ligure to 1220 cu. ft. per horse power per day, even under high wind conditions, thus resulting in a fuel saving of 20%.

Since it is obvious Ithat certain changes can be made in the foregoing constructions without departing from theA spirit and scope of this invention, it is intended that all matter shown in the accompanying drawings or described herein before shall be interpreted as illustrative and not in a limiting sense. l

I claim as my invention:

1. In a chimney, a vertical tubular wall forming a vertical ue therein, an imperforate top on said chimney, said wall adjacent said top forming a stack head and having a plurality of horizontally disposed rows of apertures therethrough, said rows being spaced substantially uniformly from each other, each horizontal row of apertures having an even number of apertures disposed in uniformly spaced relationship throughout the whole circumference of said stack head, each of said apertures being of uniform area, said apertures being disposed in each horizontal row so that each aperture has an oppositely disposed aperture in horizontal alignment therewith, the total area of said apertures being suicient to permit free movement of exhaust gases from the chimney as determined for still day operating conditions for said chimney, whereby when wind blows against one apertured portion of the stack head, the vacuum created at the opposite apertured portion of the stack head is offset by the wind owing through the apertures in the lirst portion to the aligned apertures in the-second portion, whereby the action of the wind regardless of direction or velocity in acting on any apertured portion of the stack head does not change the uniform draft of still day operating conditions in said chimney.

2. In a chimney, a vertical tubular wall forming a vertical llue therein, said wall adjacent said top forming a stack head and having a plurality of horizontally disposed rows of apertures therethrough, said rows being spaced substantially uniformly from each other, each horizontal. row of apertures having an even number of apertures disposed in uniformly; spaced relationship throughout the whole circumference of said stack head, each of said apertures being of uniform area, said apertures being disposed in each horizontal row so that each aperture has an oppositely disposed aperture in horizontal alignment therewith, the total area of said apertures .being sufficient to permit free movement of exhaust gases from the chimney as determined-for still day operating conditions for said chimney, whereby when wind blows against one apertured portion of the stack head,

regardless of direction or velocity in acting on any apertured portion of the stack head does not change the uniform draft of still day operating conditions in said vchimn chimney, said vertical tubular wall having a plurality of horizontally disposed rows of apertures therethrough,

said rows being spaced substantially uniformly from each other, each horizontal row of apertures having an even number of apertures disposed in uniformly spaced relationship throughout the whole circumference of said vertical tubular wall, each of said apertures being of uniform area, said apertures being disposed in each horizontal row so that each aperture has an oppositely disposed aperture in horizontal alignment therewith, the total area of said apertures being sufficient to permit free movement of exhaust gases from the chimney as determined for still day operating conditions for said chimney, whereby when wind blows against one apertured portion of the draft equalizing stack head, the vacuum created at the opposite apertured portion of the stack head is offset by the wind flowing through the apertures in the first portion to the aligned apertures in the second portion whereby the action of the wind regardless of direction or velocity in acting on any apertured portion of the stack head does not change the uniform draft of still day operating conditions in said chimney. 4. A draft equalizing stack head according to claim 3 including means for holding said stack head in adjustable position on the top of said chimney.

5. A draft equalizing stack head adapted to vertically surmount the flue of a chimney, said stack head having a vertical tubular wall forming a ue therein, an open top end and an open bottom end, said open bottom end being adapted to be connected with the top ofthe chirnney so that the ue of the chimney is in communication with the flue of said stack head, means for securing said stack head to said chimney, said vertical tubular wall having a plurality of horizontally disposed rows of aper- `tures therethrough, said rows being spaced substantially uniformly from each other, each horizontal row of apertures having an even number of apertures disposed in uniformly spaced relationship throughout the whole circumference of said vertical tubular wall, each of said apertures being of uniform area, said apertures being disposed in each horizontal row so that each aperture has an oppositely disposed aperture in horizontal alignment therewith, the total area of said apertures being sufficient to permit free movement of exhaust gases from the chimney as determined for still day operating conditions for said chimney, whereby when wind blows against one apertured portion of the draft equalizing stack head, the vacuum created at the opposite apertured portion of the stack head is offset by the wind flowing through the apertures in the first portion to the aligned apertures in the second portion whereby the action of the wind regardless of direction `or velocity in actng on any apertured portion of the stack head does not change the uniform draft of still day operating conditions in said chimney.

6. A draft equalizing stack head according to claim 5 including means for holding said stack head in adjustable position on the top of said chimney. D

7. -A draft stabilizing device for mounting in the top of a chimney to project vertically upward from the chimney, comprising a thirnble adapted to be telescopically received within the top end of the chimney, a transversely extending annular plate attached to the top end of said thimble and extending transversely of the top of said chimof said transversely extending annular plate, and

ney and adapted to rest thereon, an annular vertically extending elongated shell attached to the outer periphery an imperforate plate attached to and closing off the top end of said shell, the vertically extending wall of said elongated shell having a plurality of horizontally disposed rows of apertures therethrough, said rows being spaced substantially uniformly from each other, each horizontal row of apertures having an even number of apertures disposed in uniformly spaced relationship throughout the whole circumference of said elongated shell, each of said apertures being of uniform area, said apertures being disposed in each horizontal row so that each aperture has an opposite-l ly disposed aperture in horizontal alignment therewith, the total area of said apertures being sufficient to permit free movement of exhaust gases from said chimney as determined for still day operating condition for said chimney with no wind blowing, whereby when wind blows against one apertured portion of the elongated shell, the vacuum created at the opposite apertured portion of the elongated shell is offset by the wind owing through the apertures in the first apertured portion to the aligned apertures in the second portion whereby the action of the wind regardless of direction or velocity in acting on any apertured portion of the elongated hollow shell does not change the uniform draft of still day operating condition in said chimney.

8. A draft stabilizing device for mounting in the top of a chimney to project vertically upward from the chimney, comprising a thirnble adapted to be telescopically received within the top end of the chimney, a transversely extending annular plate attached to the top end of said thirnble and extending transversely of the top of said chimney and adapted to rest thereon, an annular vertically extending elongated shell attached to the outer periphery of said transversely extending annular plate, the vertically extending wall of said elongated shell having a plurality of horizontally disposed rows of apertures therethrough, said rows being spaced substantially uniformly from each other, each horizontal row of apertures having an even number of apertures disposed in uniformly spaced rela tionship throughout the whole circumference of said elongated shell, each of said apertures being of uniform area, said apertures being disposed in each horizontal row so that each aperture has an oppositely disposed aperture in horizontal alignment therewith, the total area of said apertures being suflcient to permit free movement ofv exhaust gases from said chimney as determined for still day operating condition for said chimney with no wind blowing,

whereby when wind blows against one apertured portion of the elongated shell, the vacuum created at the opposite apertured portion of the elongated shell is offset by the wind flowing through the apertures in the first apertured portion to the aligned apertures in the second portion whereby the action of the wind regardless of direction or velocity in acting on any apertured portion of the elongated hollow shell does not change the uniform draft of still day operating condition in said chimney.

References Cited in the file of this patent UNITED STATES PATENTS 363,236 Hodel May 17, 1887 544,390 Shannon Aug. 13, 18.95 1,222,794 Quinn Apr. 17, 1917 1,930,050 Hilt Oct. 10, 1933 2,060,364 Chase Nov. 10, 1936 2,381,178 Munyon Aug. 7, 1945 2,598,603 Richtarsic May 27, 1952 2,630,748 v Brockelsby Mar. 10, 1953 FOREIGN PATENTS 964,531 'France Feb. 1, 1950