CA1229845A - Apparatus and method for mixing and distributing solid particulate material - Google Patents

Abstract

APPARATUS AND METHOD FOR MIXING AND
DISTRIBUTING SOLID PARTICULATE MATERIAL
ABSTRACT OF THE DISCLOSURE
An apparatus and method for mixing and distributing solid material in which the material is continuously introduced into a vessel and a pressurized gas is introduced into the lower portion of the vessel at a velocity sufficient to pass upwardly through the material in the vessel to promote mixing of the material. A plurality of outlets are disposed in an angularly spaced relation along the vessel for permittting the material to continuously discharge to a plurality of selected locations. The excess gas in the vessel is removed, cleaned and introduced back into the vessel.

Description

APPARATUS AND METHOD FOR MIXING AND
DISTRIBUTING SOLID PARTICULATE ~ATERIAL

BACKGROUND OF THE INVENTION
This invention relates to a mixing and distributing apparatus and method, and more particularly to such an apparatus and method in which one or more materials are mixed in a vessel and distributed from the vessel~
'rhe use of fluidized beds has long been recognized as an attractive way of generating heat. In these type of :Lo arrangements, a particulate material, including a mixture of fuel material, such as coal, and an adsorbent material for the sulfur released as a result of the combustion of the fuel material, are disposed on a grate or grate-like plate. Air is passed through the bed to fluidize the material so that the bed behaves as a boiling liquid which promotes the combustion of the fuel.
Additional fuel and adsorbent material must be continuous-ly supplied to the bed through a plurality of overbed or inbed feeders disposed at spaced locations along the walls of the vessel housing of the fluidized bed. Since in many arrangements a plurality o~ material inlets are provided through two or more walls of the vessel, it becomes difficu]t from a materials handling standpolnt to recei.ve the fuel materials and the adsorbent materials from separate sources, mix them and uniformly clistribute them to the selected locations along the walls of the vessel.
In order to promote the mixing and improve the handling capabiity of the material it has been suggested to pass a stream of air through the materials. However, since the air discharged with the mixed solids is only a relatively small percentage of the air flow required to insure proper mixing, a considerable amount o e~cess air is present in the system which must be removed to insure proper operation.

SUMMARY OF THE INVENTION
Accordingly, the present invention see~s to provide an apparatus and method in which solid particulate material is received from separate sources, is mixed and is discharged in a precise and uniform manner.
In one broad aspect, the invention pertains to an apparatus for rnixing and distributing solid particulate material, the apparatus comprising a vessel for supporting a bed of the ma-terial with inlet means associated with the vessel for receiving additional material for the bed. Means are provided for introducing a pressurized gas into the lower portion of the vessel at a velocity sufficient to pass throuc3h the central portion of the bed and cause a spouting of -the particles from the upper surface of the bed, thereby forming a central zone in which the concentration of particles in the gas is relatively low and the particles move upwardly with the gas, and an outer zone surrounding the central zone in which the concentration of the paxticles is relativel~r high and their general movement is downwardly. A plurality of outlets are disposed ln a spaced relation around the vessel and communicate with the outer zone for permitting the mixed rnaterial to discharge from a plurality of areas of the vessel.
Outlet means permit the gas to discharge from the upper portion of the vessel and means is connected to the gas outlet means for separating from the gas the solid particlcs entrained Ln the gas and means is provided for injecting the solicl particles back into the bed.
The invention urther pertains to a method for mixiny and d;.stributing solid particulate material, the method comprising the steps of introducin(3 the particulate matericll to a ver,sel to form a ~ed of the material in the vessel, introduclng a pressurized gas into the vessel at a veloci4.y sufficient to pass througll the bed of material and promote mi~iny ot the material, clischarging the mi~ed material from the vess*l, ~,~

discharging the gas from the vessel, separatiny from the gas the solid particles entrained in the gas, and injecting the solid particles back into the bed.
DESCRIPTION OF THE DRAWIMGS
The above brief description, as well as Eurther aspects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of the presently preferred but nonetheless illust-rative embodiment in accordance with the present invention when -taken in conjunction with the accompanying drawings in which:
Fig. 1 is a schematic view of the system of the present invention;
Fig. 2 is a front elevational view, partially in section, of the mixing and distributing apparatus of the system of Fig. l;
Fig. 3 is a cross-sectional view taken along the line 3~3 of Fig. 2;
Fig. 4 is a vertical cross-sectional view taken along the line 4-~ o~ Fig. 3;
Fig. 5 is a view similar to Fig. 4 bu-t depicting an alternate embodiment of the apparatus of the present invention;
and Fig. 6 is a horizontal cross-sectional view taken along the line 6-6 of Fig. 5.
DESCRIPTION OF' THE PREFERRED EMBODIMENT
Referxing specifically to Figs. 1 and 2 of the drawings, _ ., the reference numeral 10 refers in general to an elonga~ed cylindrical vessel having an ~pper inlet 12 I.~hich is adap.ed .
to receiva particulate matexial from one or more sources (no-t shown), The particulate material can, for the purpose of example, bP a source of crushed coal for a fluidized bed and ~ source of limestone for adsor~ing ~he sulfur formed as a result o~ combustion of the coal.

The lower end portion of the YeSsel 10 is formed into a . .
conically shaped hopper 14 which has an inlet 16 re~istering with its apex for receiving a pressurized gasr such as air, rom an externai source, which air passes upwardly throug~

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the vesse~ in a manner to ~e described in detail later.
.
Four equianyularly spaced outlet pipes 18 :(two of which are shown in Fig. 1) extend at an acuta an~le with respect to a hori20nal plane from a point ~ithin the vessel 10, through . the vessel wail and to a point externally of tlle ve~sel.

The material from the sà~ce or ~ources mentioned above is introduced into the upper inlet 12 of tha vessel 10 and ~lows downwardly through the ves3el ~y graYity before acc~nulatin3 in the vessel~ Air is introducea into the ` inlet 16 and passe~ through the hopper 14, and upwardly .
through the material accumulating in the vessel 10. The ~
velocity and flow o~ the air are re~ul~tecl so that "s~o~lking"
occurs, i.e~, a porti.on of the materials .~rGm the bed in the vessel will b~ discharged upwardl~ fxc)m the upper surf~ce of the bed. ~s wiil be described later, this induces a circula-tion of ma~erials in the bed and an improved ~ixinc3 o~ same.

The considerable amount of excess air xising upwardly in the vessel 10 from the bed of particulate material exits through an opening f~r~ed in the up er portion oE tne vessel 10 and into an outlet line 20. A recirculating blower 22 is provided which operates to drain the air from the up~er portion of the bed vessel through the line 20 and into a solicl separating device 2¢ of any conven-tional design, such as a cyclone separator. The separating device 24 operates in a conventional manner to remove a great majority o~ the solid bed particles ~rom -the air, which solids are passed ~2rtically downwardly ~hrough a line 26 containing a rotary valve 28 to a reinjectio~ nozzle 30. The output of the blower 22 is connected, via a line 32, to ths inlet wside of the reinject-ing nozzle 30 which operates to entrain the solid particle~

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passing ~ro~ the valYe 28 and introduce them, via a line 34, . to the inlet 16 of the vessel 10. The rotary valve X8 func-.. - tiOIls as.a seal ta prevent back10w or air from the hi~h .. pressure side of the blower 22 to the low p~essure ~one in the separating device 24 The air outlet oE the separating device 2~ is connected, via a line 36, to a second-stage separating devlce 38 wnich also can be in tlle form o a cyclone sepa~ator. Although not shown in the dra~iings, it is understood that the solids outlet ~rom the separating device 38 can be di~charaed to another vessel or the like.

The air outlet rom the separ~ting device 38 is con-nected, via a line ~0, back to ~lle inlet side o~ the recir-cula-tion blower 22 for injection back into the system. ~h~s, the suction from the blower 22 draws the air from the vessel 10, throu~h the separators 2~ and 38 and ~o ~he blow~r 22. A
., heat exchan5er 42 can be provided in the line 40 to cool.the recycled air passing through the latter line, especially if the hea-t removed with the air-solids mixture from the vessel 10 is not su~ficient to compensate for the heat add2d b~ tne recirculation blower 22 without excessive temperature ~uildup in the bed in the vessel 10.

Figs. 2-4 depict the specifics of the vessel 10 in more detail~ More particulaxly, it is noted that four outlet ',...''..,,.~'',--~'pipes 18 extend ~rom the vessel and are covered by a refractory -, ' material 44. As better shown i~ Fig. 4, ~ filler plug 46 i5 ( .provided in ~he .vessel immediately above the hopper portion 14 and has a central bore 48 ~hrough which the air from the -.. inlet 16 passes,' which bore widens out into a substantially t - ' ' ' - '~; ' -' '-conical shaped.opening 50 ~hich receives the material flowing , downwardly in the vessel~ As a result o~ this ~low ol the ,-, air through.~he material, a cen~ral zone, shown in general . . .. ~.. . . .
, by the re~erence numeral 60 is formed ~hich is concentxic .,: .- . ., .. - .
~o ,.with the axis o,the vessel 10 a~d in which the concentration of the particles is low and the general movement of the ' parA~kicles is upward~ An annular zone 62 is ~lso formed which extends around the central zone 60 and in ~hich the concentration of the particles is hi~h and the ~eneral - '' .
movement is downward. The cen-tral zone 60 is continually supplied with particles from the ~nnular zone 62 in the vicini~.y of the openin~ 50 which particles a~e thus tr~ns-.ported to the upper part oE the bed by means of the pres-surized air and then fall ~ack down into the annular zone 62 and repeat the'cycle. A~; a result, a thoro-tgh mi.xing of t~e particles w;~hin the bed is achieved.

,, --6--During movement of the particles in the annular zone 62 downwardly, a portion will enter the upper ena of the discharge pipe 18 and be transported, ~y gravity, throu~h -th~ entire length of the pipes to areas external of the vessel 10. In the present embodiment in which four such pipes 18 are provided, it can be appreciated -that a precis~
distribution of the mixed particles into four seoarate locations is thus achieved. In the case of a fluidized bed discussed above, a ductin~ system, or the like, can be provided to connect the outlet ends of the pipes 18 to the feeders associated with the walls o~ the vessel housing the fluidized bed. ~~

~-~ ....... Of course, the supply o~ new particulate material to the inlet 12 o~ the vessel 10 i~ regulated according to the discharge from the pipes 18 so that a continuous replenish-ing oi the particle material in the vessel 10 is achieved.

:.- Of course~ the excess ai.r ~usually in excess o~ ~0~ of ., . . - ~ . .
the air discharged from the pipes l~) passes upwardl~ into the upper portion o~ the vessel and out throug~ tne line ~a . . ..
;~or treatmen-t and recirsulation by the separ~-ting devi.ce 2~, the blower 22, etc., as described above.

. ~n alternative embodim~nt o~ the ve~sel 10 ,~s depicted -in ~ig.s. 5 and. 6 and includes identical components of the latter vessel which are glven the same reference nu~eral~, wi~h tlle particula-te materi~1 being omit-ted from the drawings in the int~rest o~ clarity. In this embodiment, the filler plug 46 of the previous em~odiment is omitted ~nd fou~

A ., .

g8 equiangularly spaced inlet pipes 64 are provided which extend through the wall of the hopper portion 1~ of the vessel and at an angle to the horizontal. The pipes 64 receive the particulate material from one or more sou_ces as in the previolls embodiment and feed the material into the lower portion of the hopper 14 imrnediately above the air inlet 16.

A central æone and an annular zone are thus formed and the flow pattern of the material in the vessel is the same as discussed in connection with the previous embodimen~ -.. .: . . . . .
Four vertically extending, angularly spaced, discharge i pipes 66 extend ~rom a point inside -th vessel 10, and through the inclined wall~ of the hopper 1~ for discharging the particulate material t~ four separa~e external locations . . .
. in a manner similar ~o that in connection with ~he embodiments . ... . . .
o~ ~igs. 2-4.;. Of course, ~he vessel o the e~bodimen~. of ,, . . . .:
Figs. 5 and 6 can be used with the recirculating, se~arating .
and reinjecting apparatus depicted in Fi~. 1.

It is thua seen that, as a result of -~he foregoing, a ~o precise mixing and distributiGn of the pa~ticulate ~aterial -xom one or more sources to a plurality o~ discha~ge points i~.achieved in.a relatively simple and`efficient ~anner while the excess air frorn the vessel is used in an efficien-t manner.

It is noted that several variations may be ~ade in the foregoing. Fo~ example, if the vessel 1~ is ope~ted at, or near, atmospheric pressurer the recyd ed air line 40 , 8~

(Fiy. 1) and the heat exchanger 42 can be omitted, and t'ne air leaving the second-stage separa-ting device 38 can be discharged to atmosphere and the blower 22 can ta~e su_tion from the atmospnere.

As will ~e apparent to those skilled in the art, various change's and modifications may be made to the apparatus of the present inven-tion without departing from the spirit and scope of the present invention as recited in the appended claims and their legal eguivalent.
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Claims (15)

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:

1. An apparatus for mixing and distributing solid particulate material, said apparatus comprising a vessel for supporting a bed of said material, inlet means associated with said vessel for receiving additional material for said bed, means for introducing a pressurized gas into the lower portion of said vessel at a velocity sufficient to pass through the central portion of said bed and cause a spouting of said particles from the upper surface of said bed and forming a central zone in which the concentration of particles in the gas is relatively low and said particles move upwardly with the gas, and an outer zone surrounding said central zone in which the concentration of said particles is relatively high and their general movement is downwardly, a plurality of outlets disposed in a spaced relation around said vessel and communicating with said outer zone for permitting said mixed material to discharge from a plurality of areas of said vessel, outlet means for permitting said gas to discharge from the upper portion of said vessel, means connected to said gas outlet means for separating from said gas the solid particles entrained in said gas and means for injecting said solid particles back into said bed.

2. The apparatus of Claim 1 wherein each of said outlet means is in the form of a pipe extending from said outer zone, through said vessel and to an area external of said vessel.

3. The apparatus of Claim 2 wherein said vessel has a generally cylindrical shape and wherein said pipes extend through circumferentially spaced openings extending through said vessel.

4. The apparatus of Claim 1, 2 or 3 wherein said separating means comprises a cyclone separator.

5. The apparatus of Claim 1 wherein said injecting means comprises an injecting nozzle, and a blower connected to the inlet of said injecting nozzle.

6. The apparatus of Claim 5 further comprising a second-stage separating means connected between the gas outlet means of said separating means and said blower.

7. The apparatus of Claim 5 further comprising means connecting said blower to the gas outlet of said separating means for injecting the clean gas from said separating means to said nozzle.

8. The apparatus of Claim 6 further comprising means connecting said blower to the gas outlet of said second-stage separating means for injecting the clean gas from said second-stage separating means to said nozzle.

9. The apparatus of Claim 7 or 8 further comprising a heat exchanger connected to said connecting means.

10. The apparatus of Claim 2 wherein said pipes extend at an angle relative to the axis of said vessel.

11. The apparatus of Claim 2 wherein said pipes extend parallel to the axis of said vessel.

12. The apparatus of Claim 1, 2 or 3 wherein said inlet means for said material is located in the upper portion of said vessel.

13. The apparatus of Claim 1, 2 or 3 wherein the inlet means for said material is located in the lower portion of said vessel.

14. The apparatus of Claim 1, 2 or 3 wherein the inlet means for said material is in the form of a plurality of spaced pipes extending through said vessel at an angle relative to the axis of said vessel and communicating with the lower portion of said vessel.

15, The apparatus of Claim 1, 2 or 3 further comprising means disposed in said vessel for defining a conical hopper portion in said vessel, said gas introducing means registering with the apex of said hopper portion.