Draft regulator for chimneys

Jan. 30, 1940. e. n. berg 2,188,564

DRAFT REGULATOR FOR CHIMNEYS

Filed Feb. 8, 1939

<img file="US2188564A_D0001.tif" />

Patented Jan. 30, 1940

2,188,564

UNITED STATES PATENT OFFICE

2,188,564

DRAFT REGULATOR FOR CHIMNEYS

Edward N. Berg, Minneapolis, Minn., assignor of one-half to Floyd F. Schultz, Minneapolis, Minn.

Application February 8, 1939, Serial No. 255,269

Claims.

My invention relates to chimney cowls and particularly to chimney cowls having a draft-regulating action.

In connection with heating plants it is desirable 5 to have an ample but not excessive draft when operating with a heavy fire and a relatively slight draft when operating with only a small fire since too much draft for a given size of fire will cause poor economy in the use of fuel for the reason 10 that the hot gaseous products of. combustion will pass cut of the furnace before very much of the heat contained in the gases has been transferred to the heating system.

A object of my invention is to provide a draft15 regulating device the action of which will not be affected by atmospheric conditions and which will cause the draft to vary in accordance with the size of the fire in the furnace until a maximum draft condition is secured whereupon no greater 20. draft will be obtained even if the furnace fire burns more strongly.

Another object is to provide such a draft-regulating device which will be highly sensitive to furnace fire conditions and which may be ad25 justed as to the sensitivity of operation thereof and the maximum draft obtainable therewith.

Still another object is to provide such. a regulation device which is adapted to be installed on the top of any chimney without necessitating any 30 appreciable changes being made in the same.

A further object is to provide such a regulator of simple, light, rugged and inexpensive construction.

These and other objects and advantages will be 35 more apparent from the following description made in connection with the. accompanying drawing, wherein like reference characters refer to the same or similar parts throughout the. several views, and, in which:

Fig. 1 is a vertical sectional view of a preferred embodiment of my invention shown in operative association with a chimney:

Fig. 2 is a sectional view taken on the line 2—2 of Fig. 1 as indicated by the arrows;

pig. 3 is a sectional view taken on the line 3—3 of Fig. 2 as indicated by the arrows;

Fig. 4 is a sectional view taken on the line 4—4 of Fig. 1 as indicated by the arrows, and

Fig. 5 is a vertical sectional view of another 50 form of my device.

Referring to the drawing and particularly to Figs. 1 to 4 inclusive thereof, an embodiment, of my invention is shown in operative relation with a chimney 6. A vertically disposed tubular mem55 ber 7 is placed upon the top of the chimney in (Cl. 98—78) . - ' . S communication with the interior thereof to project upwardly therefrom. The member 7 comprises one of the parts of my device when the same is constructed for use in connection with a ..... chimney built of brick or the like but, where my 6 device is to be applied to the top of a tubular steel stack or the like, the member 7 may consist of the uppermost portion of the tubular stack.

An outer member 8 of hollow frusto-conical ,., form is disposed in co-axial relation with the 10 tubular member 7 with the lower portion of the outer member 8 associated with the upper part of the tubular member 7 in radially outwardly spaced, partially telescoped relation therewith so .... as to leave an. annular space or passage 9 there- i® between. Several brackets 10 are provided connecting the lower portion of the frusto-conical member 8 to the upper portion of the tubular member 7 for support therefrom.

An inner element i I of tubular shape is placed 20 within the frusto-conical member 8 in co-axial relation with the same and the tubular member 7. The lower portion of the tubular element ί I is telescoped into the upper end of the tubular member 7 in radially inwardly spaced relation there- ²⁵with so as to provide therebetween an annular space or passage 12 In communication with the interior of the tubular member 7. The upper edge of the tubular element is in radially inwardly spaced relation with the upper portion of the ³⁰frusto-conical outer member 3 so as to provide an annular passage 13 therebetween.

The inner tubular element I ί is so arranged as to be adjustable in diameter for the purpose of adjustively varying the effective cross-sectional 35 area of the annular passage 12 previously described. The tubular element is formed of a pair of rectangular sheets of material rolled and assembled into tubular form as indicated’in Fig. 2 with longitudinally extending marginal portions 40 thereof overlapping in a circumferential direction. As shown in Fig. 4, one of the overlapping marginal portions, at each joint between the respective sheets, is apertured and the other overlapping marginal portion is provided with circum- ⁴⁵ferentially extending slots Ila, and nutted bolts 14 are extended through the slots 14 and apertured portions to enable adjustive variation in the degree of overlap and locking of the overlapping portions in any adjusted relation thereof. ⁵⁰

Means is provided for supporting the inner tubular element 11 from the outer frusto-conical member and permitting adjustive longitudinal movement of the inner tubular element I I relative to the. frusto-conical member 8 for the pur-5®

2,188,564 pose of adjusting the effective cross-sectional area of the annular passage 13 therebetween. As shown in Fig. 3 radially inwardly projecting apertured brackets i 5 are provided on the inner side of the frusto-conical member 8 in line with the medial portion of the tubular inner element !!. Angle pieces i 6 having longitudinal slots 16α and 16b in the respective legs thereof are associated with the brackets 15 and the tubular element I i ¹⁰ as shown for interconnecting the same. Nutted bolts IT are passed through the apertures of the brackets i 5 and the slots i 6α of the angle pieces 16 to interconnect the same and nutted bolts I 8 are passed through the slots 16b of the angle piece ¹⁵ 16 and apertured portions of the inner tubular element I i to connect the angle pieces I 6 to the tubular element I i. The slot-equipped connections between the brackets 15 and the angle pieces 16 enable adjustment to compensate for adjustive ⁰ variation in the diameter of the tubular element f I in the manner previously described. The slotequipped connections between the angle pieces 16 and the tubular element I i enable adjustive longitudinal movement of the tubular element I! rela™ tive to the frusto-conical outer member 8 to vary the cross-sectional area of the passage 13 therebetween. Where the cross-sectional area of the passage 13 is changed due to¹ adjustive change in the diameter of the tubular elementI I, compensa™ tion for this change may be made by raising or lowering the inner tubular element II.

In operation of the device the hot flue gases rising in the tubular member 7 will divide with part thereof passing upwardly through the in⁰ terior of the inner tubular element 11 and part passing upwardly through the annular passage 12 and then through the annular passage 13 to draw cold air therewith through the passage 9. The hot gases passing through the passage 12 will 40 mix with the cold air entering through the passage 9 before the mixture thereof passes upwardly through the passage 13. Above the top end of the inner tubular element 11, gases and air passing upwardly from the passage 13 will create 45 the equivalent of a venturi for exerting suction on the gases issuing from the upper end of the inner tubular element 11, and hence will increase the effective degree of draft. The extent of the above described venturi action will vary up to a 50 maximum set limit as the temperature of the flue gases increases and hence a strong draft will exist when a large fire is burning and a very mild draft will exist when a small fire is burning in the furnace connected to the chimney 6.

.55 Variation in the area of the passage 13 varies the degree of suction or draft obtained for any given conditions and determines the maximum draft that can be obtained in any chimney. Variation in the area of the passage 12 varies the 60 sensitivity of the device as to speed of adjustment of the draft to the fire conditions. Adjustments of the areas of these passages by means cf the adjustment features previously described will adapt the device for use with heating plants and 65 chimneys of widely different characteristics.

Due to the venturi action which constantly takes place outside atmospheric conditions cannot affect the chimney draft. Thus down draft or irregular draft is prevented. In other words &lt;70 when the draft created by the device under a hot fire has reached a certain pressure, the friction of the air running through passage 13 is such by reason of the size of the passage that no greater draft can be created. Thus adequate draft for a ,75 hot fire is secured without excessive draft τ,ο waste fuel when the device is adjusted properly to produce a passage 13 of the proper size.

Fig. 5 illustrates another form of the device wherein the adjustment features are not incorporated. This form of the device includes a ⁵tubular member 19, a frusto-conical outer member 20 and a tubular inner element 21 respectively similar to the tubular member 7, frusto-conical outer member 8 and the inner tubular element 11 of the previously described form of the device ³⁰in all particulars except that the inner tubular element in Fig. 5 is of fixed rather than adjustable diameter. The frusto-conical outei· member 20 is connected to the tubular member by means of brackets 22 similar to the brackets 10 ¹⁵of the first form of the device. The inner element 21 is connected near its upper end to the frusto-conical outer member 20 by means of nonadjustable brackets 23. The principle of operation of the device of Fig. 5 is, of course, the ²⁰same as the principle of operation described in connection with the first form of the device.

Full sized models of the device have been built and placed in regular service over a period of time and have been found to improve the fuel -° economy of heating plants to a very substantial degree.

It is apparent that I have invented a novel, simple, effective and inexpensive form of draft regulator for the chimneys of heating plants. ³⁰

It will, of course, be understood that various changes may be made in the form, details, proportions and arrangement of parts without departing from the scope of my invention.