US2742328A - Apparatus for feeding pulverulent material - Google Patents

Description

April 17, 1956 K. J. SYLVEST 2,742,328

APPARATUS FOR FEEDING PULVERULENT MATERIAL Filed March 2, 1954 IN VEN TOR.

Karl Jens Sylvest, Copenhagen, Denmark, assignor to.

p F. L. Smidth & Co., New York, N. Y., a corporation of New Jersey Application March 2, 1954, Serial No. 413,559

Claims priority, application Great Britain November 3, 1953 9 Claims. (Cl. 30229) This invention relates to the feeding of pulverulent material and is concerned more particularly with a novel apparatus, by which such material may be fed from a region atone pressure to a region at a different pressure, while maintaining a seal between the regions. The new apparatus may be employed for various purposes and affords special advantages, when used to feed finely divided material into a stream of hot gases to be entrained and heated thereby. Such a heating installation is useful in pro-heating cement raw material to be burned in a kiln and, in that installation, the apparatus may be utilized to feed the material into the hot kiln gases traveling to a cylone or like separator or to deliver the material into a kiln.

The apparatus of the invention may be of different constructions and its essential features are a pipe for conducting the material in a generally downward direction, means at the lower end of the pipe, which changes the direction of travel of the material and holds a body of the material effective to seal the pipe, and means for continually removing part of the body of material for feeding purposes without destroying the seal. The means for changing the direction of travel of the material and holding the body of material sealing the pipe may take various forms, such as a bowl, into which the pipe extends, or an approximately right angle bend in the pipe plus a generally horizontal extension from the bend. The means for continually removing part of the body of material acting as a seal preferably includes a p ervious support for at least an outer marginal part of the body and means for diffusing air through the support into the material thereon, so that the aerated material continually flows off the support and material flows at the same rate from the conduit to maintain the sealing body.

For a better understanding of the present invention,

reference may be had to the accompanying drawing, in which: Fig. l is a fragmentary View, partly in elevation and partly in section, of an installation for preheating cement raw materials, in which the new feeding apparatus is employed; and

Figs. 2-6, incl., are vertical sectional views of different forms of the feeding apparatus of the invention.

The installation illustrated in Fig. 1 comprises a rotary cement kiln it together with means utilizing hot gases from the kiln for preheating the raw materials to be burned in the kiln. In the installation, the upper end of the kiln extends into a hood or dust chamber 11, from which the gases are led through a conduit 12 to the inlet of a cyclone separator 13 having a hopper bottom 13a with an outlet for solids. A conduit 14 leads from the gas outlet of separator 13 to the inlet of a second cyclone separator 15 having a hopper bottom 15a with a solids outlet. The gases issuing from the outlet of separator 15 are led to the atmosphere through a conduit 16 and, in order to provide the desired gas flow, the conduit is connected to the intake of a blower 17.

The raw material is supplied from a bin 18 through United States Patent ice a pipe 19 to a feeding device 20 of the invention, and the device feeds the material through a pipe 21, which dis charges the material into the gas stream flowing through conduit 14, The gases entrain the material and carry it to separator 15, in which the solids are separated from the gases and collect in the hopper bottom 15a. The solids from separator 15 travel through a pipe 22 to another feeding device of the invention, which is designated 23 and lies within conduit 12. The solids fed by the device 23 are picked up in the gas stream traveling through conduit 12 and carried into separator 13, in which the solids are separated from the gas and collect in hopper bottom 13a. The solids leaving the hopper bottom 13a are conducted through a pipe 24 to another form 25 of the new feeding device, which lies within a casing 26 having an outlet pipe 27 extending through the dust chamber 11 and into the upper end of the kiln.

In the installation described, the raw materials are pre-heated by heat from the gases carrying the materials along and, at each place where the materials are discharged into a gas stream, a form of the new feeding device is employed to feed the materials and maintain a seal. Also, a form of the new device is employed to feed the heated materials into the kiln while preventing the atmosphere from entering the kiln.

The feeding device 26 shown in a larger scale in Fig. 2 includes a casing 28, in which is mounted an open receptacle 29 formed of a pneumatically permeable material, such as filter stone, asbestos cloth, metal gauze, or metal felt, canvas, and the like. The receptacle is shaped like a bowl and it is supported by a gas-impermeable horizontal partition 30 within the casing out of contact with the bottom of the casing. The pipe 19 passes through the top wall of the casing and extends intothe receptacle a short distance. The upper end of the discharge pipe 21 extends into the casing and terminates at the level of the horizontal partition. A gaseous medium, such as air, is supplied under relatively low pressure through a line 31 containing a valve 32 to the interior of the casing 28 between the bottom wall of the casing and the receptacle;

In operation, the cement raw material flowing from bin 18 through pipe 19 tends to form a pile at the bottom of the receptacle 29, as indicated by the dotted lines, and, if no air were supplied through line 31, the material in the pile would assume a position determined by the head of material in pipe 19 and would prevent further discharge of material through the pipe and thus seal the pipe. When valve 32 is opened and air enters the casing and'is diffused through the wall of the receptacle into the material, the material is fluidized, so that it spreads and flows laterally. As a result, additional material may flow into the receptacle from pipe 19. When the receptacle is filled, the overflow passes out of the casing through pipe 21 and is discharged into the gases in the conduit 14. The material contained within the receptacle serves as a gas seal for the end of the pipe 19, thus permitting a pressure differential to be maintained in the conduit 14 and the bin 18. The rate of flow of the material through the device 20 may be varied by adjusting valve 32 to vary the volume of air delivered to the casing. If valve 32 is closed, the fluidized material in the receptacle will be de-aerated and settle to a level just above the end of pipe 19, thereby maintaining the seal. If, for any reason, the flow of material to the receptacle is stopped, the fluidized material already within the receptacle forms a gas seal, the level of the material remaining in the receptacle always being high enough to cover the end of the pipe 19. i

In the form of the feeding device shown in Fig. 3 and generally designated 33, the pipe 34 supplying the raw materials extends into a conduit 35 containing flowing gases and terminates with a lower flared end 36 having a radial flange 37. A chamber 38 is mounted within conduit 35 on the end of an air line 39 extending through an opening in the wall of the conduit and the chamber has a fiat top 40 opposed to the end 36 of pipe 34 and of about the same diameter as flange 37. The central part 40a of top 40 is formed of a gas-impermeable material and the surrounding annular part 40b is made of a gas-permeable material, similar to the materials used for the receptacle 31.

In the operation of the device, the material flowing from the feed pipe 34 forms a conical pile on the top of chamber 38, and the head of material in pipe 34 is such that the lower edge of the pile covers the annular portion 40b of the top. The pile seals the lower end of pipe 34 and, when air under relatively low pressure is supplied by line 39 to chamber 38, theair is diffused through the gas-permeable annulus 40b into the material thereon to fluidize the material. The material at the edge of the pile is thus enabled to flow freely ofl the edge'of the top' of chamber 38 into the gas stream in conduit 35 and the pile is continually replenished by material discharged from pipe 34. If the supply of material is shut OE, and the level of the material in pipe 34 drops below a given point, the pressure exerted by the column of material in the pipe is not suflicient to force the lower edge of the heap outwardly far enough to cover the annular portion of the top of chamber 38. As a result, the pile of material below the flared end of the pipe and the flange is adequate to seal the end of the pipe. If the air pressure is cut off, the seal formed by the pile of material is still maintained, because the pressure exerted by the column of material in the pipe is not suflicient to cause the material to flow off the edge of the top of the chamber.

The device shown in Fig. 4 is similar to the feeding device 33 (Fig. 3), except that the lower end of the feed pipe 34' is not flared, and the end of the pipe and chamber 38' are enclosed in a housing 41 with a hopper bottom 41a. Air supplied to chamber 38' through a line 39 escapes through the annular gas-permeable portion 40b of the top 40' of the chamber to fluidize the outer marginal portion of the pile of material, which collects on the top. The fluidized material then flows 01f the top of the chamber into the hopper bottom 41a and leaves the housing through pipe 42.

The form 25 of the feeding device shown in Fig. includes a right angle bend 24a at the lower end of the supply pipe 24 and a horizontal extension 2411 of the pipe beyond the bend. The extension communicates with the interior of the casing 26 through an opening in the side wall of the casing; A chamber 43 is mounted in casing 26 with its top even with the bottom of the opening, to which pipe extension 24b leads. The top of the chamber is of gas-permeable material and air under relatively low pressure is supplied to the chamber through I a line 44 containing a valve 45. The length of the horizontal extension 24b of the pipe 24 beyond the bend is such that the pressure exerted by a column of material of a given height within the vertical portion of the pipe causes the material to fill the extension and flow onto the permeable top of chamber 43. If the column of material is less than the given height, the material will flow only to the end of the horizontal portion of the pipe and form the sloping end surface indicated by the dotted line 46. Under both condtions, the material within the tube forms a gas seal.

In operation, the air passing through the partition fluidizes the material coming in contact therewith with the result that a marginal part of the body of material forming the seal is continually removed by the pressure exerted by the column of material. The rate of flow of the material through the feeding device into pipe 27 may be controlled by varying the amount of air supplied to ,chamber 43 and the flow of material may be stopped entirely by shutting off the flow of air.

In the modification of the feeding device shown in Fig. 6, the material supplied by the feed pipe 47 flows into a casing 48 and collects upon the sloping bottom wall 48a of the casing beneath a partition 49 extending downwardly at an angle from the top of the casing to terminate a short distance above wall 48a. A chamber 50 subdivided into two compartments 50a, 50b by a partition 51 is disposed at the lower end of bottom wall 48:: with the top 52 of the chamber forming a continuation of the wall. The top of the chamber is made of gas-permeable material and air is supplied to the compartments through branches 53a, 53b from an air line 53, the branches containing respective valves 54a, 54b. A discharge pipe 55 leads from the bottom of casing beyond the top 52 of chamber 50.

When material is fed to casing 48 through feed pipe 47, the material collects on the bottom wall 48a beneath partion 49 and forms a pile sealing the opening between the wall and the lower end of the partition. Part of the material passes through the opening onto the top of compartment 50a and, when air is supplied to the compartments, it escapes through the gas-permeable top walls of the compartments and fluidizes the material thereon. As a result, the fluidized material flows down the top wall of the compartments and is discharged through pipe 55. By subdividing the air chamber into two or more compartments, a saving in air is effected because, after the material is initially fluidized by the air in the first chamber 50a, only a small amount of air is required to maintain the fluidization of the material passing over the second compartment 50b.

I claim:

1. Apparatus for feeding pulverulent material through an opening in a wall having ditferent pressures on opposite sides thereof which comprises means connected to the wall at the opening and including a pipe for conducting the material in a generally downward direction and means at the lower end of the pipe changing the direction of travel of the material without lateral confinement along at least one side and holding a body of material effective to seal the pipe, said holding means including a gas-impermeable surface beneath the lower end of said pipe for receiving material from said pipe and for supporting the main part of the body of pulverulent material, a gas-permeable support for the remainder of the body of material, said gas-permeable support lying beyond the gas-impermeable surface and at least in part at the side of the wall to which the material is to be fed, and means for passing a gaseous medium through the gas-permeable support to render the material on said support sufiiciently fluent to flow off said support, the gas-permeable support being beyond the place at which material from said pipe is delivered to said gas-impermeable surface a distance such that when pulverulent material in the lower end of said pipe is under asubstantial head, the pulverulent material will flow along the gas-impermeable surface and onto the gas-permeable support, and when pulverulent material in the lower end of said pipe is under no appreciable head, the pulverulent material will be retained on the gas-impermeable surface, whereby pulverulent material on the gas-impermeable surface and in the lower end of the pipe forms a gas seal independent of the extent of the head of material in the pipe and the flow of gaseous medium through the gaspermeable support.

2. Apparatus for feeding pulverulent material which comprises a pipe for conducting material in a generally downward direction and having a flared lower end with a. radial flange, a plate facing the flared end of the pipe, the central portion of the plate being opposite the open end of the pipe and adapted to receive pulverulent material from said pipe to seal the pipe and being gasimpermeable, the surrounding portion of the plate being gas-permeable, and means for passing a gaseous medium through the gas-permeable portion of the plate torender the material thereon sufficiently fluent to flow off the plate, the surrounding gas-permeable portion of the plate being beyond the place at which material from said pipe is delivered to the central gas-impermeable portion a distance such that when pulverulent material in the lower end of the pipe is under a substantial head, the pulverulent material will flow along said central gas-impermeable portion onto the surrounding gas-permeable portion, and when pulverulent material in the lower end of the pipe is under no appreciable head, the pulverulent material will be retained on the gas-impermeable central portion, whereby pulverulent material on the gas-impermeable central portion and in the lower end of the pipe forms a gas seal independent of the extent of the head of material in the pipe and the flow of gaseous medium through the gas-permeable support.

3. Apparatus for feeding pulverulent material which comprises a conduit, a pipe for conducting material into the conduit in a generally downward direction, a plate beneath and facing the end of the pipe, the central portion of the plate being opposite the open end of the pipe and adapted to receive pulverulent material from said pipe to seal the pipe and being of gas-impermeable material, the surrounding portion of the plate being gaspermeable, a chamber having the plate as its top wall, and means for supplying a gaseous medium to the chamber to pass through the gas-permeable portion of the plate to render the material thereon sufficiently fluent to flow off the plate, the surrounding gas-permeable portion of the plate being beyond the place at which material from said pipe is delivered to the central gas-impermeable portion a distance such that when pulverulent material in the lower end of the pipe is under a substantial head, the pulverulent material will flow along said central gasirnpermeable portion onto the surrounding gas-permeable portion and when pulverulent material in the lower end of the pipe is under no appreciable head, the pulverulent material will be retained on the gas-impermeable central portion, whereby pulverulent material on the gas-impermeable central portion and in the lower end of the pipe forms a gas seal independent of the extent of the head of material in the pipe and the flow of gaseous medium through the gas-permeable support.

4. Apparatus for feeding pulverulent material, which comprises a casing having a hopper bottom with an outlet for pulverulent material, a pipe for conducting material in a generally downward direction into the casing, a chamber within the casing and having a top upper wall beneath the lower end of the pipe, the central portion of the top upper wall being opposite the open end of the pipe and adapted to receive pulverulent material from said pipe to seal the pipe and being gas-impermeable,

and the surrounding portion being gas-permeable, means for supplying a gaseous medium to the chamber to pass through the gas-permeable portion of the top and render the material thereon sufliciently fluent to flow ofi the top.

5. Apparatus for feeding pulverulent material, which comprises-a pipe for conducting material in a downward direction having at its lower end a bend and a generally horizontal extension beyond the bend, the wall of the pipe being gas-impermeable, a chamber mounted with its top substantially even with the lower inner surface of the extension, the chamber top being gas-permeable, and means for supplying a gaseous medium to the chamber for escape through the top to render the material thereon sufliciently fluent to flow off the top, the material on the top being correspondingly replenished from the pipe.

6. Apparatus for feeding pulverulent material, which comprises a casing having a side wall with an inlet for ing material in a downward direction and having at its "lower end a bend and a horizontal extension beyond the bend connected to the casing inlet, the wall of the pipe, including the head and extension being gas-impermeable, and means for supplying fluid medium to the chamber to escape through the top to render the material supported thereon sufliciently fluent to flow off the top, the material on the top being correspondingly replenished from the pipe.

7. Apparatus for feeding pulverulent material, which comprises a casing having a top wall with an inlet for material and a sloping gas-impermeable bottom wall with an outlet for the material near its lower end, a partition within the casing extending downwardly at an angle from the top wall and terminating a short distance above the bottom wall, a chamber having a permeable top forming a continuation of the bottom wall of the casing and disposed adjacent to the material outlet, means for supplying material through the casing inlet to form a pile partly on the bottom wall beneath the partition and partly on the top of the chamber, and means for supplying a gaseous medium to the chamber for escape through the top to render the material thereon sufflciently fluent to flow oil the top and through the outlet, the material on the top being correspondingly replenished by the material supplying means.

8. Apparatus for feeding pulverulent material which comprises a casing having a top wall with an inlet for material and a sloping gas-impermeable bottom wall with an outlet for the material near its lower end, a partition within the casing extending downwardly at an angle from the top wall and terminating a short distance above the bottom wall, a chamber having a gas-permeable top forming a continuation of the bottom wall of the casing and disposed adjacent to the material outlet, at least one partition subdividing the chamber into compartments, means for supplying material through the casing inlet, the material forming a pile partly on the bottom wall beneath the partition and partly on the top of the chamber, means for supplying a gaseous medium to the compartments for escape through the top to render the material thereon sufliciently fluent to flow off the top, the material on the top being correspondingly replenished by the material supplying means, and means for controlling the flow of fluid medium to the respective compartments.

9. Apparatus for feeding pulverulent material which comprises a pipe for conducting the material in a generally downward direction, a wall disposed beneath and spaced from the lower end of the pipe, the wall having a central gas-impermeable portion and a peripheral gas-permeable portion and projecting outwardly beyond the pipe sufliciently to support a pile of the material eflective to seal the lower end of the pipe, and means for passing a fluid medium through the gas-permeable portion to render fluent the material in the part of the pile resting upon said portion and thereby cause said material to flow over the edge of the wall, the peripheral gas-permeable portion of the wall being beyond the place at which material from said pipe is delivered to the central gas-impermeable portion a distance such that when pulverulent material in the lower end of the pipe is under a substantial head, the pulverulent material will flow along said central gasimpermeable portion onto the peripheral gas-permeable portion, and when pulverulent material in the lower end of the pipe is under no appreciable head, the pulverulent material will be retained on the gas-impermeable central portion, whereby pulverulent material on the gas-impermeable central portion and in the lower end of the pipe forms a gas seal independent of the extent of the head of material in the pipe and the flow of gaseous medium through the gas-permeable support.

References Cited in the file of this patent UNITED STATES PATENTS

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