US2590202A

US2590202A - Material discharge mechanism

Info

Publication number: US2590202A
Application number: US625239A
Authority: US
Inventors: Jr Charles L Norton
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1944-07-04
Filing date: 1945-10-29
Publication date: 1952-03-25
Anticipated expiration: 1969-03-25

Description

March 25, 1952 c. L. NORTON: JR I 2,590,202

MATERIAL DISCHARGE MECHANISM Original Filed July 4, 1944 3 Sheets-Sheet 1 INVENTOR Char/es l. Norton ATTORNEY c. L. NORTON, JR

MATERIAL DISCHARGE MECHANISM Original Filed July 4, 1944 March 25, 1952' 9 INVENTOR.

Uzar/es l. Nortonjr BY ATTORNEY March 25, 1952 c, NORTON, JR 2,590,202

MATERIAL DISCHARGE MECHANISM Original Filed July 4, 1944 3 Sheets-Sheet 3 INVENTOR aria/7, r

ATTORNEY Patented Mar. 25, 1952 MATERIAL DISCHARGE MECHANISM Charles L. Norton, Jr., New York, N. Y., assignor to The Babcock- & Wilcox-Company, Rockleigh, N. J., a, corporation of New Jersey Original application Juiy 4', 1944, Serial No. 543,441. Divided and this application October 29, 1945, SerialNo. 625,239

9; Claims. 2

My present invention relates in general to the construction and operation of solid material dis.- charge mechanisms, and. more particularly, to mechanisms of. this character designed for operation with a material receptacle under a positive pressure and adapted to maintain a gas seal at the discharge end of the receptacle.

The general object of my invention is the provision of an. improved mechanism for controlling the discharge of a fluent mass of solid material from a chamber or receptacle under a positive pressure, while maintaining an effective gas. seal at the discharge end of the chamber or receptacle. A further and more specific object is the provision of an improved mechanism for controlling the discharge of a fiuent mass of solid material train a chamber under a positive pressure which insures a continuous discharge of the solid material while maintaining an effective gas seal at the discharge end of the chamber.

The various features of novelty which characterize my invention are pointed out with. particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred embodiments of my invention.

Of the drawings:

Fig. l is an elevation, partly in section, of a fluid heater unit incorporating discharge mechanism constructed in accordance with my invention;

Fig. 2 is a horizontal section taken on the line 2-92 of Fig. 1;

Fig. 3 is an enlarged sectional elevation of the material discharge mechanism shown in Fig. 1;

Fig. 4 is a horizontal section taken on the line 4--4 of Fig. 3; and

Fig. 5 is a partly diagrammatic sectional elevation of a modified form of solid material discharge mechanism.

My invention is illustrated as used in a fluid heater of the character disclosed in my prior application Serial No. 543,441, filed July 4 1944, now Patent No. 2,520,164, August 29, 1950, of which this application is a division. The fluid heater illustrated in Figs. 1 and 2 has a vertically elongated fluid tight metal casing l0. of circular cross-section lined with an annular wall of suitable high temperature refractory material H.

, The fluid heater interior is divided into an upper chamber [2 and a lower chamber I3 connected tinuous fluentmass, or column of refractory heat transfer material [5 of a character hereinafter described.

A heat transfer material inlet pipe 16 is connected to, the upper part of the chamber I2 v and a heating gas outlet pipe [-1, controlled by a valve 18, opens centrally into the conical top [9 oi the chamber. The material inlet pipe l6; discharges into the lower portion of an auxiliary heating gas outlet pipe 20, which opens into the chamber 12. A substantially annular combustion chamber 25: is formed by an enlarged section of the casing [0 around the lower part of the chamber l2. As shown in Figs. 1 and 2;, the inner side of the combustion chamber is formed by an annular bridge wall 26 extending upwardly for part of the height of the chamber and over which flow the heating gases generated by the combustion of any suitable fuel in the surrounding combustion space. As shown, premixed air andgas burner nozzles 21. are arranged at diametrically opposite points and substantially tangential to the combustion chamber 25. Each nozzle 21 is supplied by a valve controlled fuel pipe 2-8 and an air casing 29 to which. a secondary air supply pipe 32 is connected. The ignited mixture of fuel and air discharges through a burner block 3| into the combustion chamber 25 under a positive pressure, with the heating gases generated flowing over.- the top of the bridge wall 26 and through a circular series of gas inlet ports 32 formed between firebrick- 33 and opening into the lower part, of the chamber l2. The chamber I2 is formed with an inverted conical bottom section extending from the lower end of the ports 32 to the top ofthe throat passage Id.

The lower chamber 13 is shown as of substantially uniform circular cross-section from its upper end to a point spaced from its lowerend, the lower end portion of the chamber being downwardly tapered and defined by an inverted frusto conical metal screen 35. The lower part of the casing l0 surrounding the screen 35 is downwardly tapered in a cone 36, having a bottom discharge opening 31' which is spaced below the open lower end of the screen 35 to permit any heat transfer material passing through the screen to reach the outlet 31. The

parts

35 and 36 cooperate to define l 2 1 9 1 fluid inlet chamber 38 to which one or more valve controlled fluid supply pipes. 39 are connected for the .ad-

mission of a fluid to be heated under a positive pressure. The upper end of the lower chamber 13 is a flat firebrick arch in which a multiplicity of radial outlet slots 40 are formed in flrebrick 4|. An annular fluid outlet duct 43 surrounds the tile 42 and into which open the outlet slots 40. One or more fluid discharge pipes 44 are connected to the duct 43.

Fluid heating apparatus of this type are frequently referred to as pebble heaters, although a wide range of heat transfer materials other than pebbles can be used therein. Such materials may be ceramic refractories or corrosion resistant alloys and alloy steels, in small pieces of regular or irregular shape, such as sized grog, pebbles or crystals of mullite, silicon carbide, alumina, or other refractories. Substantially spherical pellets of uniform shape and size and formed of a mixture of calcined Georgia kaolin, raw Georgia kaolin and a binder, fired to 2850-3000 F. have been successfully used. The pellets are made of a'diameter small enough to minimize thermal shocks and impact stresses, and to provide a large amount of heat transfer surface, and yet large enough to withstand the desired gas velocities through the pellet mass without lifting. Pellet diameters /2" and have beenfound suitable.

In accordance with my invention, the downward flow of heat transfer material through the upper chamber l2, throat I4, and lower chamber 13, is controlled by a pressure-tight feeder receiving material from the pellet outlet 31, while maintaining a fluid seal on the lower end of the chamber 13. The outlet pipe 3'! opens into a small fluid tight expansion chamber 55 constructed to provide a space above the pellets at their normal angle of repose therein. The expansion chamber 50 has a bottom outlet pipe 51 provided with an adjustable sleeve extension 53 having a sharpedged lower end determining the effective position of the outlet in a subjacent valve chamber 52. The feeder mechanism is constructed to provide a periodic discharge of a small amount of pellets from the lower end of the sleeve 53. The mechanism for this purpose comprises a valve member 55 in the chamber 52 having a concave upper surface, preferably in the form of a bowl or cup having an inner central conical portion 56. The cone 56 acts to deflect the pellets outwardly on the valve member and facilitates its movement upwardly and the discharge of pellets therefrom. The cup valve member 55 is vertically movable by means of a rod 51 between an upper position shown in full lines in Fig. 3 at which the normal angle of repose of the pellets on the upper surface of the valve member is greater than the angle formed between the outer periphery of the valve member and the lower en of the sleeve 53, so that the pellets do not tend to flow over the periphery of the valve member when the latter is in its upper position, and a lower position indicated in broken lines at which the angle between the periphery of the valve member and the botvalve is moved to this position. The flow of pellets is thus dammed when the cup shaped valve member 55 is moved to its upper position without requiring any contact between the valve member and the lower end of the sleeve 53 which might V tend to crush pellets therebetween.

The valve chamber 52 has a central valve controlled bottom outlet 58 opening into a third chamber 59. The passage of pellets from the chamber 52 through the outlet 58 into the chamber 59 is controlled by a vertically movable bell valve member 65] slidable relative to the rod 51 in the chamber 59 and mounted on a hollow rod 6| surrounding the rod 51. The valve 60 is timed to open after the cup valve member 55 reaches its upper position and stops the pellet flow from the lower end of the sleeve 53. The downward movement of the valve 68 permits the pellets accumulated in the bottom of the chamber 52 to drop into the chamber 59 which has a discharge opening 52 concentric with the opening 58 and closed by a bell valve member 54 similar to the valve member 50. The valve 64 surrounds and is movable relative to the operating rods 51 an BI and is mounted on a third hollow rod 65 surrounding the

rods

57 and 51. The opening of the valve member '64 permits the pellets to drop into an inclined discharge pipe 55. The valve 64 is normally closed when the valve 60 is open and vice versa to minimize fluid leakage from and thus preserve the fluid pressure conditions in the chamber I3. The describe valve parts are coaxially arranged with the operating rods extending through a guide bearing in the discharge pipe 55.

The cup valve member 55 and bell valves 60 and 54 are intermittently operated to effect a fluid seal at all times on the lower end of the chamber l3. The operating mechanism for this purpose consists of a pair of cam members 10 and 'il rotated by a shaft 12 through suitable gearing and a belt drive from an electric motor 13. A lever 14 is pivotally mounted at 15 and arranged with one end in contact with the periphery of the cam member it. The opposite end of the lever M has a forked pivot connection with the lower end of the hollow valve rod 65 and a bracket H connects the same also to the innermost valve rod 51. With this arrangement movement of the lever 14 will cause simultaneous raising and lowering movements of the cup valve 55 and bell valve 64. The bell valve member 60 is alternately raised and lowered by a second lever pivotally mounted at 8| with one end in contact with the periphery of the'cam member H. The opposite end of the lever has a forked pivot connection with the lower end of the hollow rod 5|. The cam members 5'0 and II have their cam surfaces shaped'and relatively arranged on the shaft 12 to effect a cyclic movement of the cup valve 55 and bell valves 60 and 64. With the arrangement of the parts shown in Fig. 3, the cup member 55 and bell valves 60 and 54 are in their upper positions, the cup member having just been raised to its upper position to dam the pellet flow from the chamber 50 and the valve 64 closed after having delivered pellets from the chamber 59 to the pipe 65. The pellets previously discharged while the valve 55 is in its lower position accumulate in the bottom of the chamber 52 and the valve 60 is about to open to allow this pellet accumulation to drop into the chamber 59, the bottom outlet of which is now closed by the valve 55. The pellets drop into the chamber 59 and the valve 60 is then moved to its top closing position, after which the cup member 55 and valve 54 are simultaneously moved to their lower positions. The opening movement of the valve 8 1 permits the pellets in the chamber 59 to drop into the discharge pipe 65, while the descent of the cup member permits a new batch of pellets to flow over its periphery and accumu- 5. Iateonthebottom of the hamber 52. The parts are proportioned and timed to minimize the possibility ofany pellets becoming jammed between the valves 60 and 64 and their respective seats, while the cup member 55 is arranged so that it does not actually seat on any surface. Any upward movement of the column of pellets in the sleeve 53 during the rising movement of the cup member '5 is absorbed in the expansion chamber 50 by the movement of the pellets into the available space therein.

To insure that no pellets will be accidentally displaced and fall over the edge of the valve member 55 when the latter is in its upper or flow dammi'ng position, an annular shroud or shield H maybe arranged to contact with the peripheral edge of the valve member in that position.

The shroud is preferably of oppositely flaring vertical cross-section with its minimum diameter portion of the same diameter as. the valve member peripheral edge, to avoid binding. of the parts. The depending outlet 5| serves as a support for a vertically adjustable ring ltd connected by flexible supporting chains it? to the shroud member I 85. As the valve member moves upwardly it enters the lower flared section of the shroud, and contacts therewith in its upper posi tion. If any pellets should be caught between these parts, the flexible support of the shroud permits it: to be moved upwardly by the valve member.

The discharge pipe 66 is connected through an expansion joint 85: to a second inclined pipe 86 leading to: a box 8 at the foot of an elevator casing 88. The box 8'! opens into the elevator casing and is provided with openings through which pellets can be added or taken from the system. The. elevator casing 83 is of welded gas tightconstruction, and encloses an elevator 89, indicated as being the slow speed continuous bucket type having overlapping. buckets which are; partly filled with. pellets at the normal rate of pellet: circulation. The elevator is driven by an: electric motor: 98 having a drive connection with. the elevator headshaft. The buckets empty into. a vertical discharge pipe 91 which has its lower end opening into. an inclined pipe 92, connected through an expansion joint 93 to the inlet pipe: i5. With this arrangement a substantially continuous circulation of the heat transfer material. is maintained externally of the fluid heater between. the bottom discharge opening- 31 and the top inlet:- pipe. it, so that the mass or column. of heat transfer material within. the chambers l2 and I3 and throat 14 will descend at a predetermined, rate.

To avoid contamination of the outgoing fluids by any dust and pellet fragments formed during the circulation of the pellets, the heat transfer -material. entering through the inlet pipe I6 is preferably subjected to a. scavenging effect by a controllable portion. of the heating gases leaving the: chamber I2 through the auxiliary gas outlet conduit. 20. The. pipe. extends externally to a cyclone separator 98 having a bottom outlet 99 for separated solid material and a vent pipe Hi9 controlled by a valve. lill for discharge of the gases.

In the normal operation of the described apparatus the. heating gases generated in the combustion chamber enter the chamber l2 through the interstices. of the pellets in the gas inlets 32 under a predetermined pressure, and are substantially uniformly distributed throughout the horizontal area of the adjacent portionv of the-- 6 mass of refractory heat transfer material. The heating gases flow upwardl through the mass in intimate contact with the descending heattransfer material which reaches its maximum temperature at the level of the heating gas inlets. The heat transfer material continues its descent through the throat passage I4 into the chamber l3. The fluid to be heated, such as air, steam, or other gas or vapor, enters as a predetermined temperature and pressure through the supply pipe 39 and inlet chamber 38 and flows through the annular screen 35 into the lower end of the. heat transfer material in the chamber [3, passing upwardl y through the interstices in the material in intimate counterflow contact with the descending pellets. The entering gas is at a relatively low temperature to insure a low discharge temperature for the pellets which will provide a high thermal efficiency, lessen thermal shock. on the pellets, and permit safe handling of the pellets by the pressure-tight feeder and elevator. The. fluid. to be heated reaches its. maximum temperature at the top of the chamber l3: flowing out through the slots 46, duct 43 and discharge pipe 4d. Mixing of the fluid atmospheres. in the chambers i2 and [3 can be avoided by maintaining predetermined relative pressures in the two chambers to provide a zero fluid flow throughthe throat Hi. Pressure taps. 1.02 and H33 are indicated. for measuring the pressure differential across the throat, and variations in this condition from a predeterminedstandard are utilized to control the position of the valves i8 and till and thereby the gaseous pressure in the chamber l2 to control the relative pressures. in the two chambers; The. return of the pellets through the feeder and. elevator to the inlet pipe I6 has been previously described.

While the feeder valve operating mechanism described is normally operated to complete a cycle in a relatively few seconds, and thus provide a substantially continuous discharge of pellets from the outlet 31 and downward movement of the pellet column in the chambers I2 and 13,, the high rate of heat transfer in the chamber [3 in conjunction. with the periodic dwell of the pellets in the chamber even with. the rapid cycle of feeder operation described will result in a slight variation in. the heated fluid outlet temperature. While such temperature. variation may be negligible for most usesof the invention, in. some cases a uniform final temperature of the heated fluid maybe. important.

A. continuous discharge of pellets from the outlet 3! while maintaining the feeder under pressure is provided by the modified feeder mechanism shown in Fig. 5. Inv this construction the outlet pipe 31 has aninclined lower section 31' inwhich a vibrating feeder unit till. is incorporated. The flow area of the inclined pipe section 31 is reduced by a plate. I H therein restricting the pellet flow to one side of the pipe section below which ahorizontally extending vibrating plate H2 is located. The vibrating plate is supported and actuated by an electrically operated vibrator unit I13 in a fluid tight casing H4. The vibrating plate H2 extends into the pipe 31 for a distance sufficient to cause the pellet stream to assume an angle of repose thereon. and stop the pellet flow when the plate H2 is stationary. In operation the pellets continuously discharge from the inner end of the plate H2 at a rate depending upon the vibrating frequency and drop into an expansion chamber- 50 having a volumetric capacity sufficient to provide an expansion space above the normal level of pellets therein. The pellets periodically discharge from the chamber 50 through the outlet pipe and feeder mechanism previously described. With this feeder construction, the pellet column will continuously descend through the chambers l2 and I3 at a controllable rate.

I claim:

1. A material discharge mechanism for a receptacle containing a fluent mas of solid material which comprises a chamber having a solid material inlet and a lower solid material outlet, a valve member in said chamber, and means for moving said valve member in a timed cycle relative to said inlet between a solid material damming upper position spaced below said inlet and in which the angle of slope of a line between the periphery of said inlet and the periphery of said valve member is less than the normal angle of repose of said material on the upper surface of said valve member and a spaced lower material discharging position in which said angle of slope between said peripheries is greater than said normal angle of repose of the material.

2. A material discharge mechanism for a receptacle containing a fluent mass of solid material which comprises a chamber having a solid material inlet and a lower solid material outlet, a valve member in said chamber having a concave upper surface, an annular shield flexibly mounted between said solid material inlet and outlet, the minimum diameter of said shield being substantially the same as the peripheral edge of said valve member, and means for moving said valve member relative to said inlet between an upper position in normal contact with said shield and in which the angle of slope of a line between the periphery of said inlet and the periphery of said valve member is less than the normal angle of repose of said material on the upper surface of said valve member and a lower position in which said angle of slope between said peripheries is greater than said normal angle of repose of the material.

3. A material discharge mechanism for a receptacle containing a fluent mas of solid material under a positive pressure which comprises a valve chamber having a solid material inlet in its top and a solid material outlet in its bottom, a valve member in said valve chamber having a cup-shaped upper surface and a central conical projection in axial alignment with said inlet, means for moving said valve member relative to said inlet between an upper position spaced below said inlet and in which the angle of slope of a line between the periphery of said inlet and the periphery of said valve member is less than the normal angle of repose of said material on the upper surface of said valve member and a lower position in which said angle of slope between said peripheries is greater than said normal angle of repose of the material, and a closed expansion chamber between said receptacle and said valve chamber and arranged to receive material moved upwardly on the upward movement of said valve member.

4. A material discharge mechanism for a receptacle containing a fluent mass of solid material under a positive pressure which comprises an upper valve chamber having a solid material inlet and a lower solid material outlet and opening into a lower chamber having a solid material outlet in its bottom, a valve member in said upper chamber having a material receiving surface,

-means, for moving said valve member relative to said inlet between an upper position spaced below said inlet and in which the angle of slope of a line between the periphery of said inlet and the periphery of said valve member is less than the normal angle of repose of said material on the material receiving surface of said valve member and a lower position in which said angle of slope between said peripheries is greater than said normal angle of repose of the solid material, whereby an intermittent flow of solid material from said inlet into said upper chamber can be effected, a closed expansion chamber between said receptacle and said upper valve chamber and arranged to receive material moved upwardly on the upward movement of said valve member, a second valve member arranged to control the material outlet from said upper chamber, a third valve member arranged to control the outlet from said lower chamber, and valve operating mechanism arranged to operate said valve members.

5. A material discharge mechanism for a re ceptacle containing a fluent mass of solid material under a positive pressure which comprises an upper valve chamber having a solid material inlet in its top and a solid material outlet in its bottom and opening into a lower chamber having a solid material outlet in its bottom, a valve member in said upper chamber having a concave upper surface and in axial alignment with said inlet, means for moving said valve member relative to said inlet between an upper position spaced below said inlet and in which the angle of slope of a line between the periphery of said inlet and the periphery of said valve member is less than the normal angle of repose of said material on the upper surface of said valve member and a lower position in which said angle of slope between said peripheries is greater than said normal angle of repose of the solid material, whereby a periodic flow of solid material from said inlet into said upper chamber is effected, a closed expansion chamber between said receptacle and said upper valve chamber and arranged to receive material moved upwardly on the upward movement of said valve member, a second valve member arranged to control the solid material outlet from said upper chamber, a third valve member arranged to control the solid material outlet from said lower chamber, and valve operating mechanism having timing mechanism arranged to simultaneously raise and lower said first named valve member and said third valve member and to alternately raise and lower said second valve member.

6. A material discharge mechanism for a receptacle containing a fluent mass of solid material comprising means forming a solid material outlet from said receptacle, a movable valve member having a concave upper surface spaced below said outlet in the path of said material discharging therefrom and in a position symmetrically spaced from said outlet in which the angle of slope of a line between the periphery of said outlet and the periphery of said valve member is less than the normal angle of repose of said material on the upper surface of said valve member, whereby the flow of solid material from said outlet is dammed, and means for bodily moving said valve member to a spaced second position in which said angle of slope between the periphery of said outlet and the periphery of said valve member is greater than the normal angle of re pose of said'material on the upper surface of said valve member, said angle being regulated to control the discharge rate of fluent solid material from said. receptacle.

7. A material discharge mechanism for a receptacle containing a fluent mass of solid material comprising means forming a solid material outlet from said receptacle, a movable valve member coaxially arranged with respect to and having a peripheral configuration similar to said outlet, the upper surface of said valve being spaced below said outlet in the path of said material discharging therefrom and in a position in which the angle between the periphery of said outlet and the periphery of said valve member is less than the normal angle of repose of said material on the upper surface of said valve member, whereby the flow of solid material from said outlet is dammed. a shroud ring flexibly supported in radially spaced encirclingrelationship to said solid material outlet and contacting the periphery of said valve member when the member is in a material flow damming position, and means for moving said valve member out of peripheral contact with said shroud ring to cause the discharge of solid material over the periphery thereof.

8. A material discharge mechanism according to claim 1 wherein a vibrating member is positioned adjacent the solid material inlet to said valve chamber to cause a continuous discharge of solid material from said receptacle.

9. A material discharge mechanism according to claim 8 wherein said vibrating member is electrically operated to cause a continuous discharge of solid material therefrom when vibrated and is positioned to dam the flow of solid material when stationary.

CHARLES L. NORTON, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 791,352 Marcus" May 30, 1905 802,176 Sheldon Oct. 17, 1905 1,080,602 Stokes Dec. 9, 1913 1,382,371 McClimon et a1. June 21, 1921 1,433,109 Brown Oct. 24, 1922 1,652,250 Morrow Dec. 13, 1927 1,863,871 Pa-ckwood June 21, 1932 2,227,706 Conner Jan. 7, 1941 FOREIGN PATENTS Number Country Date 466,192 Germany Oct. 3, 1928 560,041 Germany Sept. 28, 1932