US2635565A - Induced draft system - Google Patents

Description

'April 21, 1953 L. J. HERSH INDUCED DRAFT SYSTEM Filed April 5, 1950 F1 EL 2 SHEETS-SHEET '1 I INVENTOR. \28 LLOYD J. HERSH 4 W ATTORNEY April 21, 1953 L. J. HERSH INDUCED DRAFT SYSTEM ,Filed April 3,. 1950 INVENTOR. LLOYD J. HERSH l l l I 1 1 l i I I I I I I I I I n 1 v I I I a I I I I I .i

ATTORNEY Patented Apr. 21, 1953 UNITED STATES PATENT 'OFFICE INDUCED 1 DRAFT SYSTEM Lloyd J Hersh, Oetronla, Pa.

Application April 3, 1950, Serial No. 153,542

2 Claims. (Cl. 110-162) This invention relates to induced draft,sys-

tems and more particularly to an induced draft fan and associated structure and the assembly thereof in a compact unit.

It has heretofore been proposed, in smaller boiler or furnace installations, to connect an induced draft fan directly to the stack and to the breeching from the boiler so that all of the combustion gases pass through the fan.

It has also heretofore been proposed to insert, between the fan and the breeching of the boiler, other apparatus such as cinder or dust collectors,

air heaters, and feed water heaters, and the like' This additional equipment has heretofore customarily been made as separate units, any one of which requires considerable space and is costly to manufacture and to install. Such ad.- ditional equipmentj also usually causes considerable resistance to the natural flow. of the gases. It has also heretofore been proposed .to control th volume of gas flow by resistance dampers,

I or by speed control of the induced draft fan.

The equipment for effecting automatic control of this character is rather costly.

,It has also heretofore been the practice, when employing small induced draft fans, to equip the same with bearings that are air cooled or have other provisions, dependent upon'fan rotation,

to prevent the transmission of heat through the fan shaft to the bearings. With such fans, when the fan rotation is stopped, the heat dis sipatin provisions are not effective and the heat transmitted through the shaft may cause damage to'the bearings. Also, when the fan is not being operated, the fan wheel or rotor provides considerable resistance to the natural flow of the gases.

It is the principal object of the present invention to provide an induced draft fan system, pref to provide an induced draft fan with provisions for bypassing the combustion gases when the fan is not operated.

It is a further object of the present invention to provide an induced draft fan with provisions for bypassing the combustion gases, which provisions are controlled, at least in part, by the operation or non-operation of the fan.

It is a further object of the present invention to provide, in combination with an induced draft fan, a simplified control of the path of the gases dependent upon the operation of the fan.

It is a further object of the present invention to provide a compact unit, including an induced draft fan and a separator, together with control mechanism for determining the path of the gases through the separator.

Other objects and advantageous features of the invention will be apparent from the specification and claims.

The nature and characteristic features of the invention will be more readily understood from the following description, taken in connection with the accompanying drawings forming part hereof, in which:

Figure 1 is a top plan view of a preferred em bodiment of the invention;

Fig. 2 is a front elevational view, parts being broken away to show the details of construction;

Fig. 3 is a horizontal sectional view taken approximately on the line 3-3 of Fig. 2;

Fig. 4 is a vertical sectional view taken approximately on the line 4-4 of Fig. 2; and

Fig. 5 is a vertical sectional view taken approximately on the line 5-5 of Fig. 2.

It should, of course, be understood that the description and drawings herein .are illustrative merely, and that various modifications and changes may be made in the structure disclosed without departing from the spirit of the inven tion.

Like numerals refer to like parts throughout the several views.

Referring more particularly to the drawings, a exterior casing is provided, with an upper section A, an intermediate section B, and a lower section C. The casing is preferably constructed from sheet metal plates and structural angles and in? cludes a vertical exterior front wall l0, a vertical exterior side wall H, a vertical exterior rear wall l2 parallel to the front wall 10, a vertical exterior side wall l3, parallel to the side wall H, a horizontal exterior top wall l4, and a horizontal bottom wall 15 supported on a suitable foundation (not shown).' The side, rear, top and bottom walls, at their contiguous or meeting edges, are preferably made gas-tight, in any desired manner.

The front wall i 0 at the upper portion thereof, and to one side and adjacent the wall I3, is provided with a flanged inlet opening it which is adapted to be connected to the breeching of the boiler, furnace, or the like (not shown), from which the gases of combustion are delivered.

The front wall I is also provided, below the inlet opening I6, with a cover plate I! for a manifold I8 in the interior of the intermediate section B, as hereinafter explained.

Within the interior of the casing, and intermediate the side walls I and I3, an interior partition wall 20 is provided, extending from the bottom of'the upper: section A tothe bottom wall I and from the front'wall I0 to the back wall I2. The interior of the housing is thus separated into interior chambers 2| and 22.

In the chamber 2|, an induced draft-fan is pro- 7 vided which includes a fan rotor 23 mounted on a shaft 24. A fan rotor access door |92is provided in the wall It]. The shaft 24 issupported in cutboard bearings 25 disposed beyoridthesidewall and supported on a suitable frame 26. .The. shaft 24 is preferably driven through a suitable driving connection 2 'hby an electric motor .28 whichis also supported .on a suitable'framezi. .The fan-rotor .23 vvis preferably enclosed within .a-.suitableffan 'housing3ll of scroll shape a gasinlet openingiil .to. the rotor 23 ,beingprovidedlinthe interior wall '20. "The fanhousingBfihas a gas delivery duct. l3 extending .upwar'dly therefrom, the boundary walls of which include portions of. the interior wall .20, the'frontwall II], the side wall lLan'd a'duct .wall32disposed betweentheinterior wall .23 and the side wall II and whichextends verticallyupwardly tothetop wall I4.

v.Attheupper end ofthe duct |3I, andspaced above the top wall 4, a'flange'dlgasoutlet opening .33.is provided for connection to thestack (not .shown).

,i Spaced .jdownwardly Tfrom ithe. flanged. opening .33. and disposedin the duct: I 3 I a'horizontal valve seating "flange '34 is provided on which a valve plate or vane 35. is,a.dapted.to vseat. in one of its positions and close the .duct.|3|, as hereinafter explained.

The plate 35' isconnected at one edge to a shaft to permitof swinging movement thereof. The shaft 36 extends outwardly through the side wall Hand has'an arm 3'! connected'thereto with a balance weight 38 slidable along the arm3l for adjustment, as hereinafter. explained.

"The 'ductwa'll 32. is.a1so .prov.ided, between the top wall I4 and the inner pivotal edgexof the plate .35, with an opening 33 which serves as a valve ":port,*and which is adapted-to:be partly or wholly closeldby movement of'the valve plate 35.

".The"'interior partitionwall. 2|! has an extension "20a extending to thetop'wa'll I4 and above the seating flange 34 and below the top wall I4, is

part of the compartment 22, a curved deflector 'plate"45 is mounted, extending, from the top wall 14 '-to* the rear wall |2 andbetween the interior :partition 20 and the side wall I3.

:At'rthe lower partof theupper section Av and extending from the intermediate partition 'wall 20a to the exterior wall I, and from'theexterior wall|2 to the duct 32, a horizontal partition 52 is .provided, the, space thereabove being in communi- .,cation with the inlet opening I6. Spaced inwardly from the rear wall I2, and parallel thereto, a vertical wall 41 is provided between the side wall I3 and the interior partition 20. The upper terminus of the wall 41 is approximately in line with or slightly below the lower edge of the inlet opening I6, and has a downwardly and rearwardly inclined flange 48 which, with the curved deflector plate 41, functions as a cinder trap for delivery of cinders to a cinder collecting space 49 vprovidedbetween the wall :41, and the :rear wall I2, the interior partition wallZB and the wall I3. At the lower part of this space 49, a clean out :door 5| is provided carried by the wall I2, and

.removableto permit the extraction of cinders delivered to the space 43.

JBetweengthe upper section A and the intermediate section Band at the upper part of the compa-rtmentZ Z, and aiding in the delivery of cinders to. the-cinder collecting space 49, a plurality of inclined deflector plates 59 are provided in spaced relation and at the level of the flange 48.

v.In the compartment .22, below the deflector gplatesifl, aiheat exchanger 5| ispre'ferably provided, for extraction of heat from the hot;gases .of combustion and this may .be a feed Water heater, air heater, or the like, depending upon;the specific installation. Merely by wayof illustration, the front manifold-I8 is shownas having ,a horizontal interior partition 53 and is connected by heat transfer tubes54 ,to a rear-manifold 55. The cover plate I! maybe provided witha fluid inlet connection i56lfor, the'fluid to be heated and a fluid, delivery connection 5I for the'flui'd heated in the1tubes..54.

iThemodeof operationwill now be .pointedout. With 'thejfan 2.3..sh1it down, the valve plate ':35 will be seatedon itsseat 3.4...andthe inlet |6.Will be, directly. in communication, .throughthelspace above the deflectors .50 and the .spaceabove .the horizontal .wall. 52 with ,the upper portionpf the exhaustjduct32 through the valveport 39. As soon asthe fan 23 is started, the pressure thus set up in the duct 3| willtend to. movethe valve from its seat .34 and will .tend toclosethe port 39, at least partially. .The movementand positioning of the valve..35 will .be. controlled by. the pressure conditions effective on, its opposite. faces andbythe. settingof the weight 38.

.The flow vof gas willthus be permittedthrough the inlet opening I6 then downwardly past the fdefiectorsjfl and in contact with theheat-exchanger 5|. inthelcompartment 22, then through above the wall 552' will also aid in holding the valve 35 in open position and away from the seat,34.

.By propersetting of. the weight 38, .thevalve35 can also function for volume control. Withthe valve 35in. a partially. closed position, a portion of-the gases, .by reason of the negative pressure infthechamberabove the wall 52,.will circulate back through the fan.

Itwill also be noted that the valve 35. functions asan explosiondoor and servesto prevent possible damage'toithefan, and other equipmentin position by the weight 45 and, when this weight is adjusted for normal operation, no flow will occur past this valve.

If, however, there is a reduction in the system pressure and the fan has tended to increase its capacity, the additional volume will cause the valve 42 to open, due to an increase in static pressure, permitting a portion of the gases to recirculate back through the fan. The volume of gases drawn from the boiler or furnace is thus controlled. By proper adjustment or setting of the valve 42 to effect partial recirculation, it is also possible to have the fan maintain a constant volume even though an increase in the system resistance occurs.

I claim:

1. In an induced draft system, a casing, a vertical partition in said casing separating the interior into a first and a second chamber, an inlet connection on the exterior of said casing in communication with said first chamber, a fan housing having a fan therein in said second chamber and having an inlet in communication with said first chamber, a fan discharge duct in said second chamber, an adjustable valve normally closing said duct and adapted to be moved from closed position by gas pressure from said fan, said discharge duct having a port interposed between said first chamber and said discharge duct beyond 6 said Valve, and an additional adjustable valve for controlling said port.

2. In an induced draft system, a casing having upper, intermediate and lower sections, a vertical partition in said intermediate and lower sections separating the interior thereof into a. first chamber and a second chamber, an inlet connection in communication with said upper section, said upper section and said first chamber being in communication and said upper section and said second chamber being separated by a horizontal partition, a fan housing in said lower section and in said second chamber having a fan therein and having an inlet in communication with said first chamber, a fan discharge duct in said second chamber and extending upwardly through said intermediate and upper sections, an adjustable gas pressure operated valve in said upper section normally closing said duct and adapted to be moved from closed position by gas pressure from said fan, said discharge duct having a port interposed between said upper section and said discharge duct and controlled by said valve, said discharge duct having a second port between said duct and the interior of said upper section, and an additional adjustable gas pressure operated valve in said upper section for controlling said second port.

LLOYD J. HERSH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 704,097 Phillips July 8, 1902 871,541 Wallace Nov. 19, 1907 1,369,841 Ryerson Mar. 1, 1921 2,113, 70 Waldon Apr. 5, 1938 2,125,646 Nessell Aug. 2, 1938 2,376,170 Mueller May 15, 1945

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