US2086202A

US2086202A - Fluid control system

Info

Publication number: US2086202A
Application number: US614132A
Authority: US
Inventors: Alpern Maxwell
Original assignee: AMERCIAN ENGINEERING Co
Current assignee: AMERCIAN ENGINEERING Co
Priority date: 1932-05-27
Filing date: 1932-05-27
Publication date: 1937-07-06
Anticipated expiration: 1954-07-06

Description

July 6, 1937. M. All PERN y FLUID CONTROL SYSTEM 4 Sheets-Sheet l Filed May 27, 1932 m2 w m .m

MAXWELL A/.FEEN

BY e j ATTORNEY.

July 1937.

M. ALPERN FLUID CNTROL Filed May 27,

SYSTEM I I 4 Sheets-Sheet 2 MAXWEM ALPEKN WW/W2,

ATTORNEY.

July 6, 1937.

Filled May 27, 1932 4 Sheets-Sheet 3 u? 6 4J w 3 ||FI Ik... mh

m u n.lHHI-h m2\ .M1 mlllrl .En- 1.1 m u.. um n i WN u.. 3 Jani-...Irl

IN VEN TOR. MAxwzL A mE/1 i Mln" A TT ORNE Y.

4 S-heet-Sheet 4 July 6, 1937. M. ALPERN FLUID CONTROL SYSTEM Filed May 27, 1932 IN VEN TOR.

MAXWELL ALFEN ATTORNEY,

Patented July 6, 1937 UNITED STATES PATENT OFFICE e FLUID CONTROL SYSTEMV Application May 27, 1932, Serial No. 614,132

Claims.

This invention relates to systems employed in the handling of fluids either in the gaseous or liquid state, and comprises means for controlling such fluids in passing through said systems. 5 In the accompanying drawings the invention is shown in one form Which it might take when applied to or embodied in stoker furnaces. This embodiment is only illustrative, however, as the invention is capable o-f modification and change to permit applying it tol other devices, such, for example, as Ventilating systems and hot air heating systems.

'I'he present invention contemplates a fluid system comprising a series of ducts through Which fluid from a common pressure chamber passes to sectionalized groups of tuyres or grates of a Stoker furnace. Control mechanism is associated with each duct for automatically regulating the volume of fluid passing therethrough. This mechanism is so constructed as to independently regulate the volume of fluid passing through each duct in direct proportion to the resistance offered to the free flow of uid therethrough. Thus, when the resistance to the flow of fluid in a duct increases, the volume of air passing therethrough will also increase, and vice versa; when the resistance decreases the volume of air passing therethrough will also decrease. Y

In stoker furnaces the density of the fuel bed constitutes the resistance offered to the flowof air through the various ducts. In such devices the depth of the fuel bed varies from front to rear, it having the greatest depth near the front of the stoker and gradually tapers o' toward the rear thereof. In furnaces of the type illustrated the ash forms at the top of the incandescent fuel and during operation of the furnace fusion of the ash takes place to a certain extent thereby forming clinkers which `also have a tendency to vary the density of the fuel bed. The size of the coal particles also has atendency to vary Such Aport-ions present the least resistance to the free flow of air and consequently will receive more air than is necessary for proper combustion of the fuel, and if nothing is done to check such conditions, the incandescent fuel will soon find its way to the grates and may cause serious damage thereto which can only be corrected by extinguishing the fire. 'Ihis requiresv taking a boiler 01T the line so that Workmen may replace the damaged parts and obviously results inA considerable losses to the user.

One object of the present invention is to eliminate such losses by so regulating the draft air that all portions of the fuel bed will receive proper amounts of air. In case a thin re should develop in one or more portions of the fuel bed the air supply thereto will be throttled to permit the fuel feeding apparatus to build it up to such an extent that -it will again b ecome normally uniform. The invention also functions to supply a greater amount of air to the portions of the fuel bed which become abnormally heavy, thereby increasing the rate of combustion so that these portions will also again assume a no-rmal condition.

The present invention also includes mechanism which automatically functions to permit greater or lesser volumes of air to pass through the entire system depending upon load conditions. mechanism Will function to permit greater voumes of air to pass through all of the ducts thereby increasing the rate of the Ycombustion of the fuel to meet the increased load conditions. Likewise, when the load decreases` this mechanism will also function to decrease the volume of air passing through the system so that at all times the fuel bed Will receive the proper amount of air to insure pro-per combustion vof the fuel.

Another object of the present invention, therefore, is to provide a fluid control system which automatically regulates the volume of airV passing therethrough in accordance With the load conditions under which the system operates.

A more general object of the present invention is to provide a huid system which is effective to control the volume of air passing through the entire system in accordancewith load conditions, and also to regulate the Volume of fluid passing through each -branch thereof, in accordance with the resistance offered to the flow of fluid therein. Y

A more specific object of the present invention is to Vprovide auid system having a plurality of In case the load should increase this Cil fluid motors, some of which being effective to regulate the volume of air passing through the system as a whole, depending upon load conditions, and others to regulate the ow of iiuid in the individual branches thereof in accordance with the resistance offered to the free ow of fluid therein.

A further object of this invention is to provide a draft air control mechanism for stoker furnaces which functions to vary the flow of air to the fuel bed in accordance with load conditions, and also to regulate the ilow of fluid in the individual branches thereof in accordance with the resistance offer-ed to the free iiow of air by the fuel thereabove.

A further object is to provide a draft air control for stoker furnaces comprising a series of ducts leading from a pressure chamber to sectionalized groups of tuyres, the ducts being so constructed that fuel siftings will be deflected away from the control mechanism, and conducted to hoppers positioned beneath the ducts.

Other and further objects will become apparent as the description of the invention progresses.

` Of the accompanying drawings:

Fig. 1 is a side elevational view taken through one of the retorts of the stoker showing the general arrangement of the iiuid control system.

Fig. 2 is a view taken substantially on line 2 2 of Fig. 1, with parts removed to show the mechanism for adjusting the throat dampers of the various air ducts.

Fig. 3 is a View taken on line 3 3 of Fig. 1, showing the arrangement ofthe fluid control mechanism and the apparatus for handling the fuel siftings.

Fig. 4 is a View taken on line 4 4 of Fig. 2.

Fig. 5 is a sectional side View taken through one of the control boxes.

Fig. 6 is a view taken on line 5 5 of Fig. 5.

Fig. 7 is an end View' taken on line 1 1 of Fig. 5 with the motor removed to show the construction Of the control box.

Fig. 8 is a sectional end view taken through one of the .dampers Fig. `9 is a view taken on line 9 9 of Fig. 8.

Fig. 10 is an enlarged sectional elevation view taken through the mechanism for adjusting one of the dampers.

Fig. 11 is a sectional View taken on line Il II of Fig. 12.

Fig. 12 is a view taken on line I2 I2 of Fig. 1.

In the drawings the invention is shown applied to an underfeed stoker of the inclined grate multiple retort type, of which, for the purpose of illustration, but five of the retorts are shown. It is apparent, however, that the invention is equally well adapted for use in connection with stokers of any size.

Referring to the drawings, l indicates the front wall of a furnace equipped with an underfeed Stoker of a well known type. This stoker comprises an inclined grate made up of alternating retorts 2 and tuyre rows 3. A series of alternately disposed pushers 4 and dead plates 5 are provided in the bottom of each retort and at the rear of the stoker are pro-vided extension grates 6. The pushers and extension grates are reciprocated to advance the fuel from the top to the bottom of the retorts in accordance with the well known principles of operation of this type of apparatus. The grate terminates in an ash pit 'l from which the ashes may be removed by any suitable apparatus. Beneath lthe inclined grate lstructure is a space 8 known as the plenum aosaeoe chamber, into which combustion air is forced by suitable blower apparatus (not shown) and from which the air passes through the tuyres 3 andI extension grates 5 to the fuel bed. The flow of air through the tuyres is controlled by a fluid control system which is designated generally by the numeral 9, and which will be fully described hereinafter. It may be stated here that the walls and bottom of the chamber B are sealed so that the air delivered thereto can escape only through the tuyres and grates overlying said chamber.

Fuel is fed to the upper ends of the r-etorts from hoppers I0 through the medium of main fuel feeding rams II, Fig. 1, one such ram being provided for each retort. Rams II are reciprocated in cylinders I2 with which the hoppers I0 communicate by any suitable power mechanism shown at I3 in such a manner as to force predetermined quantities of fuel emptying into the cylinders I2 from the hoppers Il) into the retorts 2. The main rams lI and the secondary pushers 4 thus advance the fuel at a predetermined rate to the bottom of the grate structure and the extension grates in turn feed the consumed fuel to the ash pit 1. The pushers 4 and extension grates 6 are also reciprocated by the power mechanism I3 through the medium of the mechanism indicated generally by numeral I4. Since the specific construction of the operation mechanism for the rams and pushers forms no part of the present invention a detail description thereof will not be given. For a complete description of this mechanism reference may be had to United States application of Herbert E. Preston, Serial No. 482,617, led September 17, 1930, and assigned to the American Engineering Company.

The walls of the retorts are comprised of side supporting plates I5 extending substantially the entire length of the stoker having a plurality of removable plates I6 attached along the upper sides thereof upon which the tuyres 3 are sup'- ported.

Referring to Fig. 1 it will be seen that each row of tuyres is divided into four groups. Communicating with each group of tuyres is a substantially rectangular air duct or passage I l, which is secured to a respective pair of side plates I5 by welding orany other suitable means. A pair of plates I 8 are provided for each duct II, which extend from the top of the. duct tothe upper edge of plates I5. In order to prevent the escape of fluid from one duct to another additional plates l9 and 20 are provided, the latter of which is fastened at one end between the adjacent tuyres of adjoining groups and is bent downwardly in close juxtaposition to the plates I6. The lower end of plate 2B is positioned between sections 2! and 22 of plate I9 and is provided with an open slot 23, extending upwardly from the bottom edge thereof so as to straddle bolts 24, which extend through elongated slots provided in sections 2| and 22 of plate I9. The slots-25 are provided in the sections of plate I9 so that when the parts have been arranged in the manner just described the sections 2l and 22 may be extended to bring the side edges thereof into contact with plates I6. The parts are then secured in this position by simply tightening bolts 24. Suitable packing 26 is then placed around the joints to effectively seal the same against air leakage.

As shown in Figs. 1 and 3, the ducts I'I depend from the lower edges of side plates I5 intothe plenum chamber 8, and are secured in any suitable manner intermediate the endsA thereof to a shedding plate 21. This plate is substantially rectangular in form and extends across the chamber 8 and inclines downwardly from front to rear thereof. The lower edge of this plate communicates with a chute 28 extending upwardly from a hopper 29. The shedding plate 21 is provided to collect the coal siftings which escape between the pushers 4 and dead plates 5. These siftings gravitate from plate 21 to chute 28 and thence into hopper 29. A second shedding plate 30 also communicates with chute 28V and is provided to deflect the siftings which pass between extension grates 6 into the chute 28. The lower end of each duct I1 has attached theretoa spout 3l which also communicates with hopper 29. The spouts 3| attached to the ducts I1 for the lower groups of tuyres communicate directly with hopper 29, while those leading from the ducts asso ciated with all of the other groups of tuyres communicate with inclined spouts 32, which in turn communicate with the hopper 29. A normally closed damper (not shown) is provided in each spout 3| to prevent the flow of air to the tuyres through said spouts. These dampers may be opened from time to time by any suitable means to discharge the fuel siftings which have accumulated thereon. Chutes 33 are provided at the upper end of spouts 32 for collecting siftings passing through the upper portion of the stoker.

As shown more particularly in Fig. 3, a control box designated generally by the numeral 34 is positioned adjacent toeach duct I1 and communicates therewith through a curved passage 35.

Each control box 34 is provided with a pair of

dampers

36 and 31, the former constituting an adjustable throat for the control box, which regulates the volume of air passing through an associated duct, and the latter constituting a throttle which is controlled by the resistance offered to the free flow of air in said duct. Thus, dur ing operation periods of the furnace a current of air will be owing from the control box through passage 35 and ducts I1. As shown more particularly in Fig. 3, the wall of each duct I1 opposite 35 is enlarged as shown at 38, forming a pocket into which the fuel siftings descending in duct I1 will be deflected by the current of air` passing therein from passage 35. The siftings then gravitate into spouts 3| and are delivered to hopper 29.

By this construction only a small portion of the fuel siftings will enter the control boxes, the quantity thereof being insucient to interfere with proper operation of the

dampers

36 and 31.

Each control box 34 comprises side walls 39 and 49 and end walls 4I and 42, the latter of which inclines inwardly as shown at 43, and then outwardly slightly as shown at 44- in Fig. 5. End wall 4I is substantially vertical and extends from top to bottom of control box 34. Spaced from wall 4I and substantially parallel thereto, is a second wall 45. A wall V46 is also provided at the bottom of the chamber defined-by the walls 39, 49, 4I and 42'. The upper sides of walls 39 and 48 converge as shown in Figs. 6 and '1, and have secured thereto a framework 41 to which is secured the curved passage 35 through which the air from the control box passesto anA associated duct I1. The upper ends of walls 4I and 42 are also secured to the framework 41. Depending from the framework 41 are a pair of vertical walls 48 and 49, the portions 56 and 5I of which extend downwardly to substantially the bottom edge of wall 42. An arcuate plate 52 se-Y cured at oneend to inner side of wall 4I-inclines downwardly therefromL and isl secured Yto edges 53 and 54 of walls 48 and 49 respectively. A wall 55 is attached to the vertical edges 56 of portions and 5I of walls 48 and 4-9 respectively, and also to the lower endof plate 52. A substantially horizontal plate 51 extends. between and is suitably secured to sidewalls 39 and 40, and also to walls 4.5 and 55. This plate is formed With a. concave depression` intermediate its ends soas to permit the plate to t snugly around arcuate plate 52. As shown. irr Fig. '1, the portions of side walls 39 and 40 adjacent portions 50 and 5I of wa11s'48 andf49. respectively, terminate upwardly of the bottom edge. of said portions and are bent through substantially ninety degrees into. contact with the latter towhich they are secured by anyV suitable means.r Thus any fuel siftings which may enter the control box through passage 35 are deflected by plate 52 and portion 43 of wall 42 into chamber 51, from which they maybe removed from time to time. by simply opening a closure 56 provided at the bottom'thereof. In the event that it should be desirable to operate the furnace without Yregulation of the draft air, it is only neeessary'tov open closures 58. The air would then. pass directly to the tuyres without having to rst'fpassthrough-

dampers

36 and 31.

Fluid from chamber 8 enters each control box 34 through aligned circular openings provided in walls 4I and 45 of said boxes and the volume thereof which. passes into the ducts I1 is regulated by throat dampers 36 which now will be blades 59 and a second series of movable bladesk 60. The bladesy 59 are arranged in spaced relation around thev periphery of the circular openings provided in walls 4I and 45 and extend between andare secured at their ends to said walls. The ends of the movableblades 60 are secured to rims 6I and 62 positioned in spaced relation within the cylindrical 'chamber defined by the blades 59. The blades 59 and 60'are so arranged that when thel damper 3.6 is adjusted to closed position blades 60 will register with the openings between blades 59 thereby preventing the passage of uid therethrough. The rims 6I and 62 are provided with hubs 63' and 64 through .which a i in any suitable manner.. These rims are also provided with hubs 69 and 16 respectively and spokes 1Iy rigidly'secure said hubs to the rims.

Adjustable thrust bearings 12 and 13 provided in hub-s 69 and 1I] respectively, engage the opposite ends of shaft 65 to support the blades 69 for movement. yIn order to prevent leakage yof air between blades 59 and rims 6I and 62 the latterv are provided with annular flanges 14 and 15. These flanges extend substantially to the inner side of blades 69 but sufficient clearance is rallowed therebetween to permit free movement of blades 60 on bearings 12 and 13.

As shown more clearly in Fig. 8, the upper series of fixed blades 59 and the lower series of s movable blades 68 of each'damper are provided with depending flanges 16. By this construction it is obvious that the friotional resistancelto the free movement of blades 60 that may Ybe caused' 75g,-

by siftings lodging on the blades is minimized.

The anges also act as scrapers to remove suchV siftings from the blades during operation of the dampers.

The damper '31 of each control box'34 is similar in construction to the throat dampers 36 and accordingly a detailed description thereof is unnecessary. Referring more particularly to Figs. 5 and 5 it is seen that walls 48 and 49 are also provided with aligned circular openings through which iiuid may pass to damper Slaafter leaving damper 36. Fixed blades extend between these walls in spaced relation around the periphery of said openings and are secured at the ends thereof to said walls in any suitable manner. Like the dampers 36 the dampers 3l are also provided with a series of spaced movable blades 18 positioned within the `chamber defined by blades 'il and when said dampers are in fully closed position the blades 18 will register with the openings between blades Tl thereby preventing the passage of air therethrough. Thrust bearings 719 and 89 are also providedwhich suitably support the blades 78 for movement.

From the foregoing description it is seen that fluid from the chamber 8 enters 4the control boxes 34 and flows in the direction ofthe arrows shown e in Figs. 3, 5 and 6 through said box and into the ducts I1 which conduct it to the tuyres 3 thereabove. All of the joints between the various walls of the control boxes 34, as well as those in the passages 35 and ducts are sealed against air leakage so that all of the fluid delivered to the tuyres must pass through this system.

The mechanismv for adjusting the dampers 36 and 3l will now be described in` detail. Referring to Figs. 1 to 4 itis seen that a fluid motor system 8| arranged outside the front wall 82 of chamber 8 is operatively connected to the movable blades 99 associated with each throat damper 36 while a separate motor 83 arranged within the chamber 8 is provided for adjusting the movable blades i8 of each damper 31.

The fluid motor system 8| comprises two parallel rows of individual motors 84a, 84h, 84e, 88d;

84e, 84j, 84g and 84h, and each row in the present instance has four motors which are connected in tandem. Through the connections shown in Figs. l, 3 and 4 between the motor system 8| and dampers 36 the combined action of all of the individual motors 8f3 will beV simultaneously transmitted to said dampers. The number of motors 8l! employed depends upon the power required to adjust the dampers 36 and it is obvious that any number thereof may be employed without departing from the present invention. Each motor 84 is supported upon angle irons 95 extending outwardly from wall 82 and the base 86 thereof being secured to a pair of said angle irons by any suitv able means such as bolts 8l,` shown in Fig. 2. The angle irons 85 are securedatl one end to wall 82 by welding and are supported intermediate their ends by angle irons 85a. depending nfrom the inclined portion 89 of wall 82p. Angle irons 85a, are also secured to wall 88 and to a row of angle irons 85 by welding or any other suitablemeans.

The motors 88 are similar in construction so that a description of one will suilice for all. Each motor 84 is constructed of sheet metal or any other suitable material and is formed with spaced cylindrical walls 69- and 99 which define an annular chamber 9|, for receiving a bell 92; The lower edge of each wall 89 and 98 is secured to a flat annular ring 93 which in turn is secured to the base 86.

It will be noted that wall 89 terminates substantially midway between the top and bottom of the motor and to the upper edge thereof is secured a. circularY plate 95 having a series of apertures 96. The upper edge of wall 9|] has also secured thereto a circular plate 91 which constitutes the upper casing for the motor. A cylindrical casing 98 having an annular flange 99 is closely tted around wall 90, the flange 99 thereof lying in abutting relation with the upper surface of plate 91. A flange |00 is also provided around the bottom edge of casing 98 which abuts against and is securedto base plate 86. Suitable sealing means is provided between ange 99 and plate 97|, and also between flange |99 and base plate 86 to prevent the escape of fluid therethrough. The annular chamber 9| may be partially filled with mercury to prevent the escape of fluid from one side of the bell to the other. t is obvious that the walls 89 and 99 and the annular ring 93 and plate 95 may be formed from a single piece of material if it is so desired.

The lower surface of bell 92 is exposed to atmospheric pressure by virtue of the apertures 96 andi 9| provided in plate 95 and base plate 86 respectively, while the upper surface thereof is exposed to the pressure in chamber 8 through the medium of a pipe |82 which, as shown in Figs. 2 and 4, has one end thereof tightly fitted in an opening provided vin plate 9'! and the other end projected through an opening provided in wall 82.

Each bell 92 has attached to the under side thereof a rod |93 which operates in suitable guides provided in

plates

95 and 86. The lower end of each rod is pivoted to a lever Yi 84 at a point intermediate the ends of the latter. Lever |04 is pivoted at its inner end to a bracket |05 depending from and suitably secured to base plate 86. The outer ends of the levers |94 are provided with couplings |88 to which are adjustably connected a series of connecting rods |81. The levers |94 for all of the motors are the same with the exception of those associated with motors 84o and 84e. These levers extend inwardly of their pivots and the inner ends thereof are also provided with couplings |89 and |99 respectively. A rod H9 is connected at its lower en-d to coupling |88 and at the upper end thereof to coupling 89. A second rod is also connected to the coupling |89 at its lower end and extends through a guide H2 l rovided in wall 88. The upper end of this rod is attached to a coupling I3 provided at the free end of the substantially horizontal arm 4 of a bell crank lever l5 pivoted to the lower end of a bracket H9 depending l:from the control box 34 associated with the top group of tuyres of the central row, as shown in Figs. l and 2. A rod il is also connected at its lower end to the coupling ||3-and at its upper end to a coupling ||8 provide-d von an arm H9 secured to and extending outwardly from the movable blades 68 of damper 35. The other control boxes 38 for the central row of'tuyres are also provided with brackets H6 depending therefrom, to which are also pivoted bell crank levers I5. The substantially horizontal arms |4 of these bell -crank leversr are also provided with couplings to which are attached the lower ends of rods lil. The upper ends of these rods are likewise attached to couplings ||8 attached to arms ||9 extending from the movable blades 879 of the respective dampers 36. The lower arms |20 of bell crank levers ||5 are also provided with couplings |2| to which are secured connecting rods |22. As shown more particularly in Figs. Zand 9, a second arm |23 extends from each of the movable blades 60 an-d also has attached thereto a coupling |24 to which are attached rods |25. Thus it is seen that all of the dampers 36 are interconnected and that any movement of the bells 92 of motors 84 will be imparted simultaneously to said dampers. Adjustable connections are provided between the Various connecting rods so that any slack between them may be taken up.

As shown in Figs. 2 and 4, the base plates of motors 83d and 83h are provided with depending bracket |26, to the lower ends of which are pivoted segmental discs |21. EachV disc is provided with an outwardly exten-ding arm having a coupling |28 to which the lower end of a `rod |29 is adjustably connected. The upper end of this rod is connected to a coupling |30 provided near the outer end of lever |04. An arm |3| is pivoted at |32 to each disc and is provi-ded with a stud |33 which operates in an arcuate slot |34 provided in said disc. A weight |35 is attached to the lower end of arm I3 I. This weight is provided with a longitudinal slot which receives the end of arm |3|, so that it may be adjustably positioned on sai-d arm. A set screw |36 is provided to secure the Weight in its adjusted position on said arm. A second arm |31 is pivoted on the opposite side of disc |21 at |32, and is also provided with a stud |38 which operates in slot |34. A weight |39 is also provided on arm |31 and also contains 'a longitudinal slot provided therein for 'receiving said arm and a set screw |40 secures the weight in adjusted position.

From the foregoing description it is seen that the weights |35 and |39 may be adjusted longitudinally of arms |3| and |31 respectively, and also toward and away from eachother by virtue of the connections just described so that the desired adjustment may be obtained. Weights |35 and |39 are provided .to balance the pressure exerted upon the uppersurfaces of the bells 95 which, it will be remembered, communicate with the chamber 8 through the medium of pipes |02. In operation the weights |35 and |39 are `posi-- tioned to balance a predetermined pressure vin the chamber 8. It therefore is. seen that in case the pressure in said chamber' should increase, the

weights will be moved bythe motors 84 about the pivot point of discs |21 a distance commensurate to the change in pressure, and will be held in this position until the pressurein chamber 6 again changes. This movement is transmitted through the various connections described hereinbefore to the movable blades of throat dampers 36, which. accordingly are adjusted to Vpermit a greater volume of .airto pass therethrough. When the pressure in the chamber 8 again becomes normal the weights |35- and |30 will actuate the dampers 36 to normal position and thus restore` the balanced condition of the system. On the other hand, if the pressure in chamber B falls below normal the balance will again be broken and weights |30 will tend to rotate disc |21 in the opposite direction, which motion through the various connections heretofore described will also be transmitted to the movable blades of throat dampers 36 with the result that .the dampers will be moved toward closed position an amount cornmensurate with the Vdecrease in pressure, thereby decreasing the volume ,of air passing therethrough. The purpose of this arrangement is to regulate the volume of air passing through the ducts 1 to the tuyres thereabove so that in case the load should decrease the damp-ers will be partially closed, thereby causing a decreased into an aperture provided in plate |48. l

|55 is secured to the central portion of bell |52 and operates in suitable guides provided in plates` 5 so adjusted by the mechanism just described that the difference in pressure between thefluid' in chamber 8 and that in control box'34 above these dampers will remain substantially constant.

The mechanism .for adjusting the dampers 31 Aof each control box Will now be described in detail. As pointed out beflore, an independent motor 83 is provided to adjustthe movable blades 18 of each damper 31. Inasmuch as the struc-r ture and operation of this mechanism is the same for all of the control boxes a description of one will suflice for all.

Referring more particularly to Figs. 5, 6 and 10, it is seen that each motor 33 is substantially the same in construction as the motors 84 and comprises a base plate 4| supported upon'a suit-V able bracket |42 attached' to and extending vfrom a control box 34 in any suitable manner, such asY by bolts |43. Each motor comprises'spaced cy lindrical Walls |44 and |45 the lower edgesiof' which are connected to an annular disc |46 which in turn is secured to base plate |4|. CircularV discs |41 and |48 aresecured to the'upper edges.

of walls |44 and |45 respectively, and a cylindrif. 3,0;

face of bell |52 communicates with thefluidin control box 34 above damper 36 V`through theA Y medium of a pipe |54. One end of .this pipe extends through wall 42A of the associated c ontrol-v box and the other end thereof istightlyfitted A rod 41 and |4| respectively. The lower endof rod |55 is pivoted at |51 to a leVerVI58, the latter of which is pivoted intermediate its ends at |59V to bracket |42. One end of lever |58 haspivoted thereto a rod |60 which is threaded at its lower end to receive a nut |6|. A series of weights |62 having apertures extending through the-axisY thereof are carried by rod |60 and areretainedr- By this arrangement the mass of weights |60 Vmay be Variedr to suitthe v conditions under which the device is V '.\perat ed. A The other end of lever |58 is provided'with a-r thereon by nut |6I.

coupling |63 to which the lower end of a rod |64 is adjustably connected. The upper end ofrod |64 is also adjustably connected to a coupling |65v provided at the outer end of an arm |66 extend ing outwardly from the movable blades -16l of damper 31. As shown in Figs. 5 and 10, a closed |58 and extends an equal distance on either side of the pivot |59 thereof.

It will be noted that only a slight clearance space is provided between the inner surfacesof walls |44 and |45 and the cylindrical portion of bell |52. By constructing the motor in this manner it is unnecessary to provide a liquid seal inasmuch as insufficient quantities of fluid may escape from one side of the bell to the other to prevent proper operation of the motor. It is sometimes impracticable to employ a liquid seal, especially when the motor is subjected to higher temperatures due to the rapid evaporation thereof. Under such conditions a motor constructed after the fashion shown in Fig. 10 is preferable.

The operation of the mechanism just described will now be briefly stated. It will be remembered that the upper surface of each bell |52 is subjected to the pressure in the associated control box 34 above damper 36, while the lower surface thereof is exposed to the pressure in chamber 8. The pressure on the lower side of bell |52 will obviously be greater than that on the upper side thereof due to the restricted opening at the throat of control box 34 through which fluid from chamber 8 must pass. In order to balance this dilerence in pressure, weights 62 are provided. When the device is placed into operation the mass of Weights |62 is regulated so as to balance the bell |52 for a predetermineddifference ,in pressure.

As has been pointed out before, the density of the fuel supported by the groups'of tuyres, with which the ducts |1 communicate, changes from time to time thus creating variable resistances to the free flow of air in said ducts. This causes the pressure in control boxes 34 also to change With the result that the motor mechanisms 83 associated therewith will be thrown out of balance. In case the density of the fuel above a group of tuyres should become greater, it is obvious that the resistance to the ow of air in the duct associated therewith will also become greater and that the pressure in the associated control box will increase a corresponding amount. The bell |52 of motor 83 will immediately res-pond to this change in pressure and will move downwardly. This downward movement is increased by the shifting of the mercury contained in box |67, thus causing the movable blades 'I8 of damper 31 to move toward open position a greater distance than they would be moved if actuated by the increased pressure alone. Thus, the fuel directly above these tuyres will receive a greater amount of air and the rate of combustion thereof will increase. Due to this increased rate of combustion the density of the fuel will soon be restored to normal and the pressure in the associated control box will decrease and the greater pressure in the chamber 8 will consequently force bell `|52 upwardly until it reaches a proper balanced position.

In case a thin fire should develop over a group of Vtuyres the resistance to the iiow of air passing through an associated duct will decrease with the result that the pressure in the associated control box 34 will also decrease. The pressure in chamber 8, however, will remain substantially the same. Therefore, an upward force will be exerted upon bell |52 equal to this change in pressure causing damper 31 to move toward closed position. When this occurs the mercury in box I6`| will shift to the other side of the pivot and the force thereof will tend to actuate the movable blades 18 of damper 31 toward closed position a greater distance than they would be moved had they been actuated by the difference in pressure alone. The fuel bed above this group of tuyres will thus receive but little air, and the rate of combustion of the fuel supported thereby will be reduced. Any damage to the tuyres that may have resulted if the rate of combustion was not checked is thereby prevented. 'Ihe fuel feeding mechanism operating at the usual rate will soon restore this portion of the fuel bed to a normal condition and the normal pressure in the control bo-x will again be restored. This pressure is immediately communicated to the upper surface of bell |52 and the mechanism will soon adjust itself tc a balanced condition and the normal volume of fluid will again pass through duct I7 to the fuel bed.

Thus it is seen that a highly sensitive uid control mechanism is provided which is wholly automatic in operation, and which insures the delivery of the proper volume of air to each portion of the fuel bed at all times. The mechanism also functions to maintain the fuel bed normally uniform thereby assuring efficient operation of the Stoker.

While the illustrated embodiment shows the invention applied to a Stoker furnace it is obvious that it is equally well adapted for use in connection with other forms of .mechanism- Instead of communicating with a group of tuyres the various ducts may lead to rooms in a Ventilating system. In case vthe resistance to the. ow of air should increase or decrease the motor mechanisms would function to either close or open the dampers, as the case may be, so that proper amounts of air would be delivered to each room of the system.

In the illustrated embodiment the ducts are shown to be in communication only with groups of tuyres. However, it is obvious that similar ducts may also be designed to communicate with the extension grates and lower grates, or any other part of the furnace which receives air from the chamber 8. The invention is, therefore, not limited to the specific embodiment shown herein and it is intended that it should be limited only by the scope of the claims which follow.

What is claimed is:

1. In a stoker, the combination of a tuyre chamber comprising spaced walls, a series of tuyre blocks spanning the space between said walls, a pressure chamber, a duct, a control unit of substantially box-like construction for each duct, a compartment formed within said unit, a damper mounted in the outer walls of said unit, and a second damper mounted in the walls of said compartment, said parts being so constructed and arranged that fluid must pass through both dampers of said control unit before entering said duct.

2. In a stoker, the combination of a tuyre chamber comprising spaced Walls, a series of tuyre blocks spanning the space between said walls, a pressure chamber, a duct extending into said pressure chamber from a group of said tuyre blocks, said duct having a restricted throat opening, a damper in said duct, means for adjusting said damper in proportion to the resistance offered to the flow of iiuid in said duct, said last mentioned means comprising a fluid motor having a floating bell, means connecting one side of said bell with said pressure chamber and means connecting the other side of said bell with the throat of said duct, means operatively connected to said motor for balancing said bell for a predetermined differential pressure, and additional means associated with said motor for actuating the same a greater distance in either direction than it would be operated by the change in differential' in pressure alone.

3. In a Stoker, the combination of a. tuyre chamber comprising spaced walls, a series of tuyre blocks spanning the space between said Walls, a pressure chambeig'a duct extending into said pressure chamber from a group of said tuyre blocks, said duct having a restricted near the throat thereof, means operatively con-v nected to said motor for balancing said bell for a predetermined diierential pressure, said last mentioned means comprising a pivoted lever having a weight at one end thereof, means operatively connecting the bell to said lever, and additional means provided on said lever for actuating said bell in either direction depending upon the change in said differential pressure, said last mentioned means comprising a closed vessel partially filled with a heavy liquid supported on said lever and extending an equal distance on either side of the pivot thereof, said` last mentioned means being so constructed and arranged that when said lever is tilted in either direction due to a change in the diierential pressure to which said bell is subjected the liquid therein will shift in said vessel thereby imparting a greater movement to said bell than'would be imparted thereto by the change in diierential pressure alone.

4. In an underfeed Stoker comprising spaced pairs of spaced walls dening parallel retorts, a row of tuyre blocks spanning the space between each pair of retort walls and forming therewith tuyre chambers, means dividing each of said tuyre chambers into a plurality of compartments each of which is subjacent a group of said blocks, means forming a pressure chamber, a duct extending into said pressure chamber from each compartment and having an adjustable throat damper operable to provide communication with said pressure chamber, automatic means operable in response to changes in pressure in said pressure chamber for simultaneously adjusting all of said throat dampers, a second damper provided in each duct, and an independent automatic means for each damper operable independently of each other and in response to changes in the differential pressure existing between said pressure chamber and the discharge side of said throat dampers for automatically adjusting each of said last mentioned dampers to throttle the flow of fluid therethrough in inverse proportion to the resistance offered to the flow of fluid through the fuel bed supported by the tuyres.

5. In a furnace Stoker, the combination of a combustion grate, comprising a series of tuyre blocks, of means forming a pressure chamber beneath said combustion grate, means dividing said tuyre blocks into a plurality of groups, one or more ducts extending into said pressure chamber from said groups of tuyre blocks, a control unit for each of said ducts having a throat damper and a control damper, automatic means responsive to changes in pressure in said pressure chamber for adjusting said throat dampers, and additional automatic means responsive to the changes in the diierential pressure existing in said pressure chamber and the discharge side of said throat dampers for adjusting said control dampers.

6. An underfeed stoker comprising spaced walls, dening parallel retorts, a row of tuyre blocks spanning the space between each pair of adjacent retort walls and extending lengthwise of said retorts, means forming a pressure charn-A ber, means dividing the tuyre blocks of each of said rows into groups, means extending into said pressure chamber from each of said groups of tuyre blocks forming passages for draft air, a throat damperfor each of said passages, means interconnecting said throat dampers for simultaneous operation .in the same direction, means for operating said throat dampers including a uid motor system responsive to changes in pressure in said pressure chamber, adjustable means operatively connected to said motor system to balance the system for a predetermined pressure in said chamber, a second damper provided in each of said passages, and independent means for actuating said second dampers.

7. An underfeed Stoker comprising spaced walls, defining parallel retorts, a, row of tuyre blocks spanning the space between each pair of adjacent retort walls and extending lengthwise of said retorts, means forming a pressure chamber, means dividing the tuyrek blocks of each of said rows into groups, means extending into said pressure chamber from each of said groups of tuyre blocks forming passages for draft air, a throat damper for each of said passages, means interconnecting said throat Vdampers for simultaneous operation in the same direction, means for operating said throat dampers including a fluid motor system responsive to changes in pressure in said pressure'chamber, and adjustable means operatively connected to said motor system to balance the system forV a predetermined pressure in said chamber.

8. An underfeed stoker comprising spaced walls, defining parallel retorts, a'row of tuyre blocks spanning the space between each pair of adjacent retort walls and extending lengthwise of said retorts, means forming a pressure chamber, means dividing the tuyre blocks of each of said rows into groups, means extending into said pressure chamber from each of said groups of tuyre blocks forming passages for Vdraft air, a throat damper for each of said passages, a second damper provided in each of said passages, independent operating means for each of said second dampers, responsive to the changes in the differential pressure existing between said pressure chamber and the discharge side of the respective throat damptuyre chambers formed by spaced side walls and a series of tuyre blocks spanning said walls, a pressure chamber, a duct extending into said pressure chamber from each tuyre chamber, said duct having a restricted throat opening, a damper in said duct, a fluid motor connected to said damper and having a fluid connection to said pressure chamber and to the throat of said duct for adjusting said damper in proportion to the resistance offered to the flow of fluid in said duct, means operatively connected toiand balancing said motor for a predetermined differential pressure between said chamber and throat, and additional means cooperating with said motor operative to actuate said motor and damper a greater distance in either direction than they would be actuated by the change in diierential pressure alone.

10. In a furnace stoker, the combination of a responsive to changes in pressure in said pressure chamber for adjusting said throat dampers, and additional automatic means responsive to the changes in the differential pressure existing in said pressure chamber and the discharge side of said throat dampers for adjusting said control 5 dampers.

MAXWELL ALPERN.