CA1323339C - Valve system - Google Patents
Valve systemInfo
- Publication number
- CA1323339C CA1323339C CA 514570 CA514570A CA1323339C CA 1323339 C CA1323339 C CA 1323339C CA 514570 CA514570 CA 514570 CA 514570 A CA514570 A CA 514570A CA 1323339 C CA1323339 C CA 1323339C
- Authority
- CA
- Canada
- Prior art keywords
- solids
- high purity
- valve
- angle
- silicon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000007787 solid Substances 0.000 claims abstract description 130
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 44
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 44
- 239000010703 silicon Substances 0.000 claims abstract description 44
- 239000000463 material Substances 0.000 claims abstract description 30
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 12
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 7
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 7
- 230000000903 blocking effect Effects 0.000 claims description 52
- 230000001681 protective effect Effects 0.000 claims description 19
- 238000007599 discharging Methods 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 238000004891 communication Methods 0.000 claims description 5
- 230000006854 communication Effects 0.000 claims description 5
- 229910002804 graphite Inorganic materials 0.000 claims description 5
- 239000010439 graphite Substances 0.000 claims description 5
- 229910000676 Si alloy Inorganic materials 0.000 claims description 2
- 239000011521 glass Substances 0.000 claims description 2
- 239000010453 quartz Substances 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims 3
- 229920005591 polysilicon Polymers 0.000 claims 3
- 238000000034 method Methods 0.000 abstract description 11
- 238000011109 contamination Methods 0.000 abstract description 9
- 239000000047 product Substances 0.000 description 51
- 239000012265 solid product Substances 0.000 description 39
- 239000007789 gas Substances 0.000 description 24
- 239000002245 particle Substances 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000012530 fluid Substances 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000008187 granular material Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 229910000077 silane Inorganic materials 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000002210 silicon-based material Substances 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 241000518994 Conta Species 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 208000034809 Product contamination Diseases 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000000806 elastomer Substances 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
- F16L55/24—Preventing accumulation of dirt or other matter in pipes, e.g. by traps, by strainers
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Filling Or Emptying Of Bunkers, Hoppers, And Tanks (AREA)
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
- Valve Device For Special Equipments (AREA)
- Electrically Driven Valve-Operating Means (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
Abstract
ABSTRACT
VALVE SYSTEM
An apparatus and process for maintaining the purity of solid/granular product and dispensing high purity granular product from a vessel. A noncontaminat-ing surface is provided by a cup, cylinder, or other structure having a surface of silicon, silicon carbide, silicon nitride, sialon, or similar materials and preferably operates as an angle of repose valve in a pressurized system to prevent contamination by undue contact of the high purity product with conventional gastight valves such as ball valves, butterfly valves, pinch valves, etc.
VALVE SYSTEM
An apparatus and process for maintaining the purity of solid/granular product and dispensing high purity granular product from a vessel. A noncontaminat-ing surface is provided by a cup, cylinder, or other structure having a surface of silicon, silicon carbide, silicon nitride, sialon, or similar materials and preferably operates as an angle of repose valve in a pressurized system to prevent contamination by undue contact of the high purity product with conventional gastight valves such as ball valves, butterfly valves, pinch valves, etc.
Description
VALVE SYSTEM
This invention relates in general to maintaining the purity of a high purity material in a pressurized system and dispensing such material. This invention relates in particular to processes, apparatuses, and valves for dispensing a high purity material from a pressurized vessel by depositing the high purity material on a noncontaminating surface and then trans~erring it only when a gastight valve is opened to dispense the 10 solid material.
Various types of standard valves hàve been used in the past to dispense gaseous, solid, and liquid materialsO Applicants have found, however, that standard valves are unacceptable for dispensing relatively hard solids that may cause valve wear. In preserving the high purity of a granular or similar solid product, valve wear also has the disadvantage of contaminating the solid product with the metal, elastomers, or other material from which the valve is constructed. Not only do the 20 valves wear out prematurely and lose their gas seal, for high purity applications the material that wears the valves becomes contaminated with impurities from the valve body. For example, a mechanically operated or gas operated elastomeric pinch valve has been used to shut ~r~
the opening of the valve, trapping between the elasto-matic walls of the valve particles of granular or similar solid product but making a gastight seal. The continued opening and closing of the elastomeric valve continues to wear on the walls of the valve so as to make the valve lose its gas seal. Similarly, ball valves and butterfly valves wear and lose their gas seal. In the process of losing the gas seal, such valves concurrently contaminate a high purity granular or similar material with carbon, 10 phosphorus, boron, nickel, or other elements present in the valve walls. Metals are particularly troublesome, especially for dispensing semiconductor materials.
When a high purity granular material such as silicon granules, gallium arsenide particles, or other III-V semiconductor materials, for example, are contained in a pressurized vessel, they will necessarily become somewhat contaminated by use of only a standard, gastight valve as described above. While this contamination may seem very minor to the casual observor, the contamination is very significant when the purity of the granules or similar material is to be maintained in the parts per million, parts per billion, or even parts per trillion range.
In certain pressurized vessels, the granules or 25 other form of solid is at relatively high temperature which can accelerate the process of wearing out the valve ~323339 and increase the rate of contamination of the high purity material from the walls or other surfaces of the valve.
The present invention addresses the problems of valve wear and contamination of high purity solid products dispensed from a vessel by providing means for dispensing the high purity product in granular or similar form in such a fashion that the product does not have undue contact with the worXing mechanism of the gastight valve of the vessel. Normally the solids are being dis-10 pensed from a protective environment.
The invention may use an angle of repose valve andan accompanying gastight valve in a protective environ-ment, preferably a gastight or pressurized environment.
The protective environment may be a high purity zone and the pressurized environment may be one with a flow of gas.
An exemplary protective environment may be merely a zone for containing solids product apart from the atmosphere. In containing semiconductor solids, separation from the atmosphere prevents accumulation of 20 carbon and other impurities otherewise gathered from dust and organic matter in the air. Thus, the protective environment may be a blanket of helium, argon, etc.
Examples of such environments are pure atmosphere containers for dispensing high purity silicon seeds to a fluid bed reactor and the fluid bed reactor itself (a pressurized environment).
By use of the combination of the invention it is possible to stop the flow of a solids material in the protective environment in such a manner that the high purity solid is not contacted with the gastight valve during its operation. There is then substantially no contact between the high purity solid and the gastight valve during discharge of the solids from the dispensing means through the gastight valve to a collection vessel, hopper, or other container. The dispensing means 10 preferably has noncontaminating surfaces for contacting the solids. The dispensing means is also preferably an angle of repose valve.
The dispensing means and angle of repose valves of the invention are preferably constructed of noncon-15 taminating materials such that the contact of solids withthe surface supporting the solids does not conta~inate the solids.
Of course, even if noncontaminating materials are not used, valve wear is avoided by use of such a 20 dispensing means. The angle of repose valve stops the flow of solids from a vessel when in a closed position and allows the solids to "seal" by virtue of their natural angle of repose against the valve seat. After solids flow has been interrupted, a gas sealing valve may 25 now be closed to achieve the gastight seal. Product contamination is avoided because high purity solids flow ~3233~9 In summary, therefore, the present invention may be considered as providing an angle of repose valve for dispensing high purity solids from a protective environment, said valve comprising: a) a housing having a top inlet and a bottom outlet; b~ an inlet tube sealingly disposed in said top inlet for receiving a flow of high purity solids from the protective environment, the inlet tube having an interior which in non-contaminating to the high purity solids for contacting the high purity solids; c) high purity solids blocking means f~r controlling the flow of high purity solids, the bloeking means being disposed within the housing and blocking but not contacting the inlet tube, the blocking means having surfaces which are non-contaminating to the high purity solids for contacting the solids, the blocking means being moveable within the housing between a first position to receive and block the high purity solids and accumulate solids in the inlet tube and a second position to unblock and discharge the high purity solids to the bottom outlet, the blocking means being cylindrical in shape, having a horizontally disposed cylindrical axis, the inlet tube extending into the interior of the cylindrically shaped bloeking means, the blocking means having a wall having a hole formed therein for discharging solids when the blocking means is in the second position, the cylindrical shaped blocking means being rotatable on its cylindrical axis to move between the first position and the s~cond position; and d) means for moving the bloc~ing means between the first position and the - 5a - 13233~
second position, the moving means being controllable from outside the housing.
Additionally, the present invention may be considered as an angle of repose valve for dispensing high purity solids from a protective environment consisting essentially of: a) a housing having a top inlet and a bottom outlet; b) an inlet tube sealingly disposed in the top inlet for receiving a flow of high purity solids from the protective environment, the inlet tube having an interior which is non-contaminating to the high purity solids for contacting the solids; c) a cylinder having solids inlet means and a bottom, inside, horizontal surface for accumulating solids thereon, the inlet tube extending into the interior of the cylinder;
and d) means for rotating the cylinder to discharge the solids from the horizontal surface.
Furthermore, the invention provides an angle of repose valve for dispensing high purity solids from a protective environment, the valve comprising: a) a housing having a top inlet for receipt into the housing of the high purity solids and a bottom outlet for discharging from the housing the high purity solids; b) a flow path between the top inlet and the bottom outlet, the path having (i) a blocking surface portion upon which high purity solids can be supported so as to obtain their natural angle of repose whereby a seal against flow is formed in the path; (ii) a first downwardly disposed portion extending from the top inlet to a point in flow communication with the blocking surface portion, and (iii) a second downwardly disposed portion extending from a - 5b - 1323339 point in flow communication with the blocking surface portion to the bottom outlet; and c) a means for opening the path to the flow of high purity solids therethrough by directing a motive gas across the blocking surface so as to move, in the same direction, those high purity solids which have formed the seal or which would form such a seal if not so moved.
132~3~9 Figure 7 is a center sectional view through Figure 8.
Figure 8 is a cross-sectional end view of a gas operated noncontaminating means which may be operated as an angle of repose valve;
Figure 9 is a cross-sectional view of a movable cylindrical noncontaminating means which rotates on its axis and may be operated as an angle of repose valve, and Figure lO is a perspective view of a portion of the unassembled cylindrical noncontaminating means of Figure 9.
Figure 11 is a schematic of a fluid bed, solids blocXing means, and hopper for solids handling.
According to the invention solids are dispensed from a vessel to a gastight valve without wear from contact between the gastight valve and the solids, and especially without such contact during opening or closing of the gastight valve.
According to the invention a high purity solid, subject to a protective environment, is suitably dis-pensed from that environment without contaminating the high purity solid by the use of a noncontaminating means (such as an angle of repose valve) in combination with a gastight valve.
A preferred embodiment of the present invention is an apparatus for maintaining the purity of a solids product ,,_ and dispensing said product from a vessel, said apparatus comprising:
(a) solids blocking means fluidly communicating with said vessel, said blocking means being operable between a first position to block the flow of and collect said product and a second position to discharge said product: and (b) valve means fluidly communicating with said blocking means to receive product discharged from said blocking means, said valve means being movable between a gastight closed position and an open position to receive the discharge from said blocking means and dispense said product from said vessel.
A preferred embodiment of the invention is also a process for di~pensing a high purity solids product from a collection vessel having a gastight dispensing valve without eroding said dispensing valve, said process comprising the steps of:
(a) blocking the flow of said product from said vessel with a nongastight noncontaminating surface upstream of said gastight dispensing valve;
(b) opening said gastight dispensing valve; and (c) unblocking the flow of said product thereby discharging at least part of the collected product through said dispensing valve.
A preferred embodiment of the invention is also a process for the production of high purity silicon, said process comprising the steps of:
(a) fluidizing a heated bed of high purity silicon seed particles with a gas stream comprising a silicon-containing compound in a reactor having a gastight silicon product dispensing valve so as to decompose silicon-containing compound and coat said 0 silicon seed particles to form high purity silicon product;
(b) blocking the flow of and collecting said high purity silicon product with noncontaminating surface below said heated bed and upstream of said gastight dispensing valve;
(c) opening said dispensing valve; and (d) unblocking the flow of and discharging said high purity silicon product [from said noncontaminating surface] through said open dispensing valve.
The apparatus of the present invention can take various physical forms and shapes so long as a noncontaminating means for stopping the flow of high purity solids is used in combination with a gastight valve means. The noncontaminating means may take various forms and shapes and suitable preferred embodiments of 1~23339 those structures for the noncontaminating means, especially angle of repose valves, and the surfaces for such noncontaminating means are given by way of example herein as well as in the accompanying drawings.
A preferred embodiment of the invention is also a high purity silicon fluid bed reactor comprising:
a fluidized bed reactor having walls defining a reaction chamber;
means for heating said reaction chamber to 0 decompose a silicon-containing gas entering said chamber;
seed particle entry means for introducing silicon seed particles into said reaction chamber;
means for introducing a silicon-containing gas into said reaction chamber to decompose said gas and form silicon product by growing silicon on said silicon seed particles;
means for exhausting decomposition gas and any unreacted silicon-containing gas from said reaction chamber; and means for dispensing silicon product from said reactor, said dispensing means fluidly communicating with said reaction chamber and comprising:
noncontaminating solids blocking means for collecting and transferring said silicon product from 25 said reaction chamber, and gastight valve means com-municating with said blocking means to receive granular silicon product discharged from said reaction chamber, and thereby dispense said silicon product from said reactor.
A preferred embodiment of the invention is also a 5 device for maintaining the purity of a high purity solid product during transfer of said solid product from a high purity zone, said device comprising:
solids blocking means for collecting said product, said blocking means having surfaces for contacting said 10 product, said surfaces being formed of a material noncontaminating to said product, said blocking means being operable to discharge said product therefrom; and valve means for discharging said product from said collection means, said valve means being operable between 15 a gastight closed position and an open position to receive therethrough the discharge from said blocking means and thereby dispense said product.
A preferred embodiment of the invention is also an angle of repose valve for dispensing high purity solids 20 from a protective environment, said valve comprising:
a housing having a top inlet and a bottom outlet;
an inlet tube sealingly disposed in said top inlet for receiving a flow of high purity solids from said protective environment, said inlet tube having a 25 noncontaminating interior for contacting said solids;
high purity solids blocking means for controlling said flow of high purity solids, said blocking means being disposed within said housing and blocking but not contacting said inlet tube, said blocking means having noncontaminating surfaces for contacting said solids, said blocking means being movable within said housing between a first position to receive and block said high purity solids and accumulate solids in said inlet tube and a second position to unblock and discharge said high purity solids to said bottom outlet; and means for moving said blocking means between said first position and said second position, said moving means being controllable from outside said housing.
In one preferred embodiment, the invention is an apparatus for maintaining the purity of a granular solid product during discharge from a storage vessel, said apparatus including:
(a) a vessel adapted to store granular solid product;
(b) a receiving vessel below said adapted vessel to receive said granular solid product;
20(c) passage means forming a fluid connection between said vessel and said receiving vessel;
(d) noncontaminating nongastight solids blocking means in said passage means; and (e) gastight valve means in said passage means 25between said nongastight solids blocking means and said storage vessel 132333~
whereby said gastight valve means can be opened and closed without errosion caused by the passage of said granular solid product through said gastight valve means during opening and closing thereby prolonging the 5 gastight life of said gastight valve and avoiding contamination of said solid product.
The solid products (solids) of the invention include all solids which are comprised of a large number of particles, granules, hunks, lumps, bits fragments, shreddings, slivers, pieces, chunks, BB's, and other moieties to make up a bulk.
According to the invention, a vessel may be considered to include a gastight valve and a solids-tight valve for dispensing product in a noncontaminating manner.
The invention may be generally described by reference to Figure 11. A container vessel 106 such as a seed particle bin, fluidized bed reactor or storage tank contains high purity solid product. The vessel 106 fluidly communicates through conduit 108 to a means 110 for alternately blocking and permitting the flow of high purity solids. The high purity solids may be transferred from the blocking means 110 through second fluid communi-cation means 112 for bulk collection in a hopper 114 or other device by transfer through a gastight valve 116.
25 Preferably, the gastight valve 116 is positioned and constructed such that high purity product passes through it without touching valve 116. Operation of the above-described apparatus permits preservation of the high purity solid in a controlled environment without con-tacting a gastight valve which could contaminate the solid and erode the valve.
In a preferred embodiment of the invention a non-contaminating means or means for avoiding valve wear is provided by a series of plates assembled as shown in Figure 1 to form a gas operated angle of repose valve 10 10 which may be threadably or otherwise connected to a noncontaminating (silicon carbide-coated graphite or silicon) tube 12 from which it receives solids such as a granular product. An end plate 18 of this assembly is shown in Figure 2. Another end plate 18 also threadably 15 or otherwise connects to a dispensing tube 14. Two next-to-end plates 16, (Fi~ure 4) are oriented in the opposite directions and placed adjacent the end plates 18 in the assembly 10. Two next-to-center plates 20 shown in Figure 5 are oriented opposite each other and placed 20 adjacent each of the next-to-end plates 16 in the assembly 10 such that the openings between the adjacent plates 16 and 20 are aligned. Finally, the center plate 22 is placed between the next-to-center plates 20 to form the serpentine flow path shown in Figure 1. Granular 25 product or similar solids entering tube 12 from above will accumulate somewhat in the space 24 of center plate 13233~
22 and build up in the space 26 of the top next-to-center plate 20 as well as in space 28 of the top next-to-end plate 16, the space 29 of end plate 18, and the inside of __ __ _ tube 12.
Thus the assembly 10 provides an angle of repose valve which operates by simply providing a horizontal blocking surface below tube 12 carrying solids downward.
The horizontal blocking surface, in this case surface 30 of bottom next-to-center plate 20 is wide enough that solids falling from above form a pile on it with a sloping surface angle e~ual to the angle of repose of the solids.
That is, without motive force, the solids falling on surface 30 do not tend to fall down into opening 26 of bottom next-to-center plate 20 but rather tend to accu-mulate as described. Since the solids cannot flow outtube 14 they are blocked and accumulate up into tube 12 and above until a motive force is applied to transfer the solids from surface 30 thereby unblocking the solids flow.
In the assembly 10 shown in Figure 1, the motive force may be applied by movement of the entire assembly, or other means such as the motion of a noncontaminating gas provided into gas inlet 32. The entire assembly 10 of Figure 1 may be made of any noncontaminating material suitable for handling the pure product entering tube 12.
Preferably, the inside diameter surface 34 of tube 12 and the remaining interior surfaces of the assembly which see 1~23339 the pure product, eithex while flow is stopped or during flow, are formed of the same material as the pure product or a composition including that material.
An angle of repose valve is particularly advanta-5 geous for the invention since a relatively small devicemay be used to accumulate solids product when used in conjunction with a tube or other container above the valve mechanism.
In a preferred embodiment of the invention, the lO high purity product is granular or BB-shaped silicon entering tube 12 and reposing on surface 30 and there-above until moved such as by entry of argon, helium, or other gas through inlet 32. The angle of repose valve thus blocks the flow of solids and fluid bed from the [vessel] fluidized bed reactor above the angle of repose valve. In such embodiment, the interior surfaces 34 and other interior surfaces of the assembly are preferably made of silicon, silicon carbide, silicon nitride, sialon (materials where the structural units are (SiAl) (O,N)4 20 or (Si,M) (O,N)4 tetrahedrawhere M is a metal), or another composition/alloy of silicon. Alternatively, the interior could be formed or coated with a noncontaminat-ing glass, quartz, or silicon carbide-coated graphite.
Alternatively, the entire assembly may be made of silicon 25 carbide-coated graphite, silicon carbide, silicon nitride, or preferably, high purity silicon. In still another embodiment the surfaces which could contact silicon are coated by plasma-sprayed silicon on the steel or other metal.
The entire assembly 10 of Figure 1 is suitably 5 disposed within an apparatus 36 shown in cross section in Figures 7 and 8. Each of the member plates, 16, 18, 20, and 22 has a dowel hole 38 (two dowel holes and dowels may be used). The plates are assembled so that each of the dowel holes _ are in line and the entire assembly lO may then be fitted into the apparatus 36 such that screw rod 40 received in the dowel holes 38 to maintain the rigid integrity of the assembly 10. A controlled supply of motive gas is connected to inlet tube 42 which is inserted through the interior wall 44 of apparatus 36 15 such that the inlet tube 42 projects into inlet 32 of the assembly 10.
In the above-described fashion, the noncontaminat-ing internal assembly 10 may be positioned within an apparatus 36 made of any suitable material such as steel, 20 stainless steel, or another metal. The exterior threaded wall 46 of tube 12 (Figure 1) and threaded wall 48 of tube 14 are threadably received within the threaded opening 50 of plate 52 (Figure 7) and threaded opening 54 of plate 56, respectively, in the apparatus 36 of Figure 25 7.
A sectional top view of the apparatus 36, taken just above the level of the inlet tube 42 but showing 13233~
plate 56 is shown in Figure 8. As can be seen, the entire apparatus 36 may be secured to the remainder of the flow path for the solid products by means of bolts or screws secured into threaded holes 58. Additionally, 5 bolts may be attached through a series OL holes 60 at the ends of plates 52 and 56 to secure the apparatus 36 tightly and make a gastight o-ring seal at 61.
Two alternative embodiments of the invention are shown in Figures 6 and 6a. Figure 6 shows a flapper style angle of repose valve 68 in the closed position with solid product 62 accumulated in the metal valve seat support 64 and accumulated in and above tube 66. The interior surfaces of tube 66 and metal valve seat support 64 which contacts solid product 62 are coated with a 15 noncontaminating material according to the nature of the solid product 62.
In the case of granular silicon product, e.g., the interior surfaces of tube 66 and support 64 are formed of silicon carbide-coated graphite, silicon carbide, silicon 20 nitride, sialon, silicon, or other noncontaminating material, preferably high purity silicon. The angle of repose valve 68 is operated so as to allow a buildup of solid product on a surface of support 64 and in tube 66 or a vessel above the valve~ When the valve 68 is 25 opened, solid product flows by gravity from above the valve. The product is collected not only immediately 13233~9 above the valve but in any tube or vessel above the valve before dispensing the product to a hopper or other container through a gastight valve (not shown) which may or may not be coated with or formed from noncontaminating materials. When valve 68 is used below a fluidized bed of solid product, the bed acts as a fluid such that if valve 68 remains open after accumulated solids are dis-pensed, then fluidized particles from the bed also begin to flow through valve 68. After the solid product 62 is collected in and above the valve 68, a gastight valve below the angle of repose valve 68 is opened and the collected solid product 62 is discharged from the valve seat support 64 by mechanically rotating handle 70 to discharge the collected silicon product 62 from the noncontaminating surfaces where the product 62 rests and above that position through the now opened gastight dispensing valve for collection, hoppering, packaging, or further processing.
If the angle of repose valve 68 shown in Figure 6 20 or other apparatus of the invention is operated in a pressurized environment which contains a dangerous gas, it is advisable to discharge the silicon product from the angle of repose valve through the open gastight valve and into a hopper or similar container which is sealed from the outside and pressure equalized with the pressurized environment. For example, if the solid product is 13233~9 granular silicon formed from silane or a silane com-position, this procedure will prevent the pyrophoric silane gas from escaping to the atmosphere. After the gastight valve below the angle of repose valve is again 5 closed, the hopper apparatus may be purged or otherwise made safe by appropriate techniques. The entire valve 68 may be contained within a housing 71 which may be constructed of any suitable material.
A schematic view of another angle of repose valve 10 72 is shown in Figure 6A. The solid product tends to accumulate at its natural angle of repose on surface 74 and build up in and above collection tube _6 as shown.
The angle of repose valve 72 of Figure 6A may be operated in much the same fashion as the angle of repose valve 16 15 shown in Figure 1. A motive gas is used to move the solid product 84 from the surface 74 and from within collection tube 76 into a hopper 78. This is accom-plished by opening gastight valve 80 and discharging a preferably noncontaminating motive gas through inlet 20 valve 82 to move the solid product 84 through the lower portion of tube 76, through the open gastight valve 80 and into hopper 78. That is, the dispensed product may free fall in a contacting or, preferably, noncontacting manner to a collection hopper. In one preferred embodi-25 ment, the opening of the gastight valve is larger thanand surrounds the tube through which solids flow. Of course it is always possible that some contact will occur between the open gastight valve and the solid product but this can be minimized by making the open I.D. of the gastight valve much larger than the drop tube 85. The resulting small amount of contact does not significantly contribute to contamination or valve wear. The invention is also advantageous because the solids do not contact the gastight valve during its operation.
After the desired amount of solid product 84 has 10 been transferred to hopper 78, inlet valve 82 is closed causing solid product 84 to again accumulate on surface 74 to close the angle of repose valve. When gastight valve 80 clears of solids it is then closed.
Referring to Figure 9, and Figure 10, the angle of repose valve 86 permits collection of silicon product in a cylinder 88 in such a fashion that solid product collects in cylinder 88 and builds up inside and above collection and entry tube ~0 thereby closing valve 86.
Preferably, the inside surfaces 92 of cylinder 88 and 94 of tube 90 are coated with or formed of a material which is noncontaminating to the entering high purity solid product. Cylinder 88 has formed in its wall a hole 96 which, when the cylinder 88 is in the open position shown in Figure 9, permits solid product to flow from the cylinder 88 and, in fact, directly from tube 90 through hole 96 into dispensing tube 98 and through an open gas-tight valve (not shown) for collection of product.
Preferably, all of the inside surfaces of the angle of repose valve 86 shown in Figure 9 which surfaces come into contact with the high purity solid product are coated with or formed of a material noncontaminating to the solid product. To close valve 86 rod 100 is rotated to move the cylinder 88 from the open position shown in Figure 9 to a closed position wherein the hole 96 is above the bottom inside horizontal surface of entry tube 90 such that the solids falling from the tube 90 above 10 form a pile on the cylinder inside wall with a sloping surface angle equal to the angle of repose of the solids. Of course, eventually the solids build up into the tube 90 in a manner according to the shape, size, and particle size distribution of the solid product thereby 15 preventing the solid product from flowing out hole 96 above the pile of solids. Thus the solids become blocked and begin to collect in tube 90 until the angle of repose valve 86 is opened by turning rod 100 to discharge the collected high purity product from the cylinder 88 20 through hole 96 into tube 98 and, preferably, through an open gastight valve for collection.
Suitably, a casing 102, which may be made of any substance such as stainless steel, carbon steel, or other material encloses the angle of respose valve 86 to 25 maintain a high purity zone or environment. The high purity zone or environment may be associated with a 13~3339 - 27. -gastight or even a pressurized zone open to the solids inthe angle of repose valve 86 since the valve is not gastight.
As may be seen in Figure 9, the cylinder 88 has a 5 cutout arcuate slot 105 formed along surface 104 which may be seen in phantom and perspective in Figure 10.
This slot _05 permits rotation of cylinder 88 without_ interference with tube 90. Rod lO0 is sealingly engaged on bearings in casing 102 so that the high purity zone, 10 gastight zone, or pressurized zone, as the case may be, is maintained. The integrity of the zone is maintained during collection of product in cylinder 88 by keeping a gastight valve (not shown) below tube 98 in the closed position.
The assembly shown for the cylinder 88 and rod lO0 may be formed in the manner shown in Figures 9 and 10 or in any convenient mechanical arrangement to effect the purposes of the invention as shown in this embodiment such that solid product may be collected and then 20 discharged from cylinder 88. Of course, the angle of repose valve 86 may be considered to include tube 90 since solid product builds up within this tube due to the angle of repose of the solid product on the surface of cylinder 88.
The embodiment of angle of repose valve 86 shown in Figures 9 and 10 is advantageous over angle of repose 132333~
valve 68 shown in Figure 6 in that dust and small particles of product associated with the bulk solids may escape from the valve seat support 64 due to turbulence around the bottom of tube 66. Valve 86, when in its 5 closed position, very nearly seals arcuate surface 104 around the bottom of tube 90, thereby preventing product from gaining entry into the closed space in casing 102 which entry would permit contamination. If product is inadvertently blown out of seat 64 in Figure 6, it can 10 accumulate on the closed gastight valve below to cause wear when the valve is opened and permit further contamination.
Having described our invention, one skilled in the art could ascertain various changes and modifications 15 thereof which are within the scope of the disclosed apparatus and process. Thus the invention is limited only by the lawful scope of the following claims:
This invention relates in general to maintaining the purity of a high purity material in a pressurized system and dispensing such material. This invention relates in particular to processes, apparatuses, and valves for dispensing a high purity material from a pressurized vessel by depositing the high purity material on a noncontaminating surface and then trans~erring it only when a gastight valve is opened to dispense the 10 solid material.
Various types of standard valves hàve been used in the past to dispense gaseous, solid, and liquid materialsO Applicants have found, however, that standard valves are unacceptable for dispensing relatively hard solids that may cause valve wear. In preserving the high purity of a granular or similar solid product, valve wear also has the disadvantage of contaminating the solid product with the metal, elastomers, or other material from which the valve is constructed. Not only do the 20 valves wear out prematurely and lose their gas seal, for high purity applications the material that wears the valves becomes contaminated with impurities from the valve body. For example, a mechanically operated or gas operated elastomeric pinch valve has been used to shut ~r~
the opening of the valve, trapping between the elasto-matic walls of the valve particles of granular or similar solid product but making a gastight seal. The continued opening and closing of the elastomeric valve continues to wear on the walls of the valve so as to make the valve lose its gas seal. Similarly, ball valves and butterfly valves wear and lose their gas seal. In the process of losing the gas seal, such valves concurrently contaminate a high purity granular or similar material with carbon, 10 phosphorus, boron, nickel, or other elements present in the valve walls. Metals are particularly troublesome, especially for dispensing semiconductor materials.
When a high purity granular material such as silicon granules, gallium arsenide particles, or other III-V semiconductor materials, for example, are contained in a pressurized vessel, they will necessarily become somewhat contaminated by use of only a standard, gastight valve as described above. While this contamination may seem very minor to the casual observor, the contamination is very significant when the purity of the granules or similar material is to be maintained in the parts per million, parts per billion, or even parts per trillion range.
In certain pressurized vessels, the granules or 25 other form of solid is at relatively high temperature which can accelerate the process of wearing out the valve ~323339 and increase the rate of contamination of the high purity material from the walls or other surfaces of the valve.
The present invention addresses the problems of valve wear and contamination of high purity solid products dispensed from a vessel by providing means for dispensing the high purity product in granular or similar form in such a fashion that the product does not have undue contact with the worXing mechanism of the gastight valve of the vessel. Normally the solids are being dis-10 pensed from a protective environment.
The invention may use an angle of repose valve andan accompanying gastight valve in a protective environ-ment, preferably a gastight or pressurized environment.
The protective environment may be a high purity zone and the pressurized environment may be one with a flow of gas.
An exemplary protective environment may be merely a zone for containing solids product apart from the atmosphere. In containing semiconductor solids, separation from the atmosphere prevents accumulation of 20 carbon and other impurities otherewise gathered from dust and organic matter in the air. Thus, the protective environment may be a blanket of helium, argon, etc.
Examples of such environments are pure atmosphere containers for dispensing high purity silicon seeds to a fluid bed reactor and the fluid bed reactor itself (a pressurized environment).
By use of the combination of the invention it is possible to stop the flow of a solids material in the protective environment in such a manner that the high purity solid is not contacted with the gastight valve during its operation. There is then substantially no contact between the high purity solid and the gastight valve during discharge of the solids from the dispensing means through the gastight valve to a collection vessel, hopper, or other container. The dispensing means 10 preferably has noncontaminating surfaces for contacting the solids. The dispensing means is also preferably an angle of repose valve.
The dispensing means and angle of repose valves of the invention are preferably constructed of noncon-15 taminating materials such that the contact of solids withthe surface supporting the solids does not conta~inate the solids.
Of course, even if noncontaminating materials are not used, valve wear is avoided by use of such a 20 dispensing means. The angle of repose valve stops the flow of solids from a vessel when in a closed position and allows the solids to "seal" by virtue of their natural angle of repose against the valve seat. After solids flow has been interrupted, a gas sealing valve may 25 now be closed to achieve the gastight seal. Product contamination is avoided because high purity solids flow ~3233~9 In summary, therefore, the present invention may be considered as providing an angle of repose valve for dispensing high purity solids from a protective environment, said valve comprising: a) a housing having a top inlet and a bottom outlet; b~ an inlet tube sealingly disposed in said top inlet for receiving a flow of high purity solids from the protective environment, the inlet tube having an interior which in non-contaminating to the high purity solids for contacting the high purity solids; c) high purity solids blocking means f~r controlling the flow of high purity solids, the bloeking means being disposed within the housing and blocking but not contacting the inlet tube, the blocking means having surfaces which are non-contaminating to the high purity solids for contacting the solids, the blocking means being moveable within the housing between a first position to receive and block the high purity solids and accumulate solids in the inlet tube and a second position to unblock and discharge the high purity solids to the bottom outlet, the blocking means being cylindrical in shape, having a horizontally disposed cylindrical axis, the inlet tube extending into the interior of the cylindrically shaped bloeking means, the blocking means having a wall having a hole formed therein for discharging solids when the blocking means is in the second position, the cylindrical shaped blocking means being rotatable on its cylindrical axis to move between the first position and the s~cond position; and d) means for moving the bloc~ing means between the first position and the - 5a - 13233~
second position, the moving means being controllable from outside the housing.
Additionally, the present invention may be considered as an angle of repose valve for dispensing high purity solids from a protective environment consisting essentially of: a) a housing having a top inlet and a bottom outlet; b) an inlet tube sealingly disposed in the top inlet for receiving a flow of high purity solids from the protective environment, the inlet tube having an interior which is non-contaminating to the high purity solids for contacting the solids; c) a cylinder having solids inlet means and a bottom, inside, horizontal surface for accumulating solids thereon, the inlet tube extending into the interior of the cylinder;
and d) means for rotating the cylinder to discharge the solids from the horizontal surface.
Furthermore, the invention provides an angle of repose valve for dispensing high purity solids from a protective environment, the valve comprising: a) a housing having a top inlet for receipt into the housing of the high purity solids and a bottom outlet for discharging from the housing the high purity solids; b) a flow path between the top inlet and the bottom outlet, the path having (i) a blocking surface portion upon which high purity solids can be supported so as to obtain their natural angle of repose whereby a seal against flow is formed in the path; (ii) a first downwardly disposed portion extending from the top inlet to a point in flow communication with the blocking surface portion, and (iii) a second downwardly disposed portion extending from a - 5b - 1323339 point in flow communication with the blocking surface portion to the bottom outlet; and c) a means for opening the path to the flow of high purity solids therethrough by directing a motive gas across the blocking surface so as to move, in the same direction, those high purity solids which have formed the seal or which would form such a seal if not so moved.
132~3~9 Figure 7 is a center sectional view through Figure 8.
Figure 8 is a cross-sectional end view of a gas operated noncontaminating means which may be operated as an angle of repose valve;
Figure 9 is a cross-sectional view of a movable cylindrical noncontaminating means which rotates on its axis and may be operated as an angle of repose valve, and Figure lO is a perspective view of a portion of the unassembled cylindrical noncontaminating means of Figure 9.
Figure 11 is a schematic of a fluid bed, solids blocXing means, and hopper for solids handling.
According to the invention solids are dispensed from a vessel to a gastight valve without wear from contact between the gastight valve and the solids, and especially without such contact during opening or closing of the gastight valve.
According to the invention a high purity solid, subject to a protective environment, is suitably dis-pensed from that environment without contaminating the high purity solid by the use of a noncontaminating means (such as an angle of repose valve) in combination with a gastight valve.
A preferred embodiment of the present invention is an apparatus for maintaining the purity of a solids product ,,_ and dispensing said product from a vessel, said apparatus comprising:
(a) solids blocking means fluidly communicating with said vessel, said blocking means being operable between a first position to block the flow of and collect said product and a second position to discharge said product: and (b) valve means fluidly communicating with said blocking means to receive product discharged from said blocking means, said valve means being movable between a gastight closed position and an open position to receive the discharge from said blocking means and dispense said product from said vessel.
A preferred embodiment of the invention is also a process for di~pensing a high purity solids product from a collection vessel having a gastight dispensing valve without eroding said dispensing valve, said process comprising the steps of:
(a) blocking the flow of said product from said vessel with a nongastight noncontaminating surface upstream of said gastight dispensing valve;
(b) opening said gastight dispensing valve; and (c) unblocking the flow of said product thereby discharging at least part of the collected product through said dispensing valve.
A preferred embodiment of the invention is also a process for the production of high purity silicon, said process comprising the steps of:
(a) fluidizing a heated bed of high purity silicon seed particles with a gas stream comprising a silicon-containing compound in a reactor having a gastight silicon product dispensing valve so as to decompose silicon-containing compound and coat said 0 silicon seed particles to form high purity silicon product;
(b) blocking the flow of and collecting said high purity silicon product with noncontaminating surface below said heated bed and upstream of said gastight dispensing valve;
(c) opening said dispensing valve; and (d) unblocking the flow of and discharging said high purity silicon product [from said noncontaminating surface] through said open dispensing valve.
The apparatus of the present invention can take various physical forms and shapes so long as a noncontaminating means for stopping the flow of high purity solids is used in combination with a gastight valve means. The noncontaminating means may take various forms and shapes and suitable preferred embodiments of 1~23339 those structures for the noncontaminating means, especially angle of repose valves, and the surfaces for such noncontaminating means are given by way of example herein as well as in the accompanying drawings.
A preferred embodiment of the invention is also a high purity silicon fluid bed reactor comprising:
a fluidized bed reactor having walls defining a reaction chamber;
means for heating said reaction chamber to 0 decompose a silicon-containing gas entering said chamber;
seed particle entry means for introducing silicon seed particles into said reaction chamber;
means for introducing a silicon-containing gas into said reaction chamber to decompose said gas and form silicon product by growing silicon on said silicon seed particles;
means for exhausting decomposition gas and any unreacted silicon-containing gas from said reaction chamber; and means for dispensing silicon product from said reactor, said dispensing means fluidly communicating with said reaction chamber and comprising:
noncontaminating solids blocking means for collecting and transferring said silicon product from 25 said reaction chamber, and gastight valve means com-municating with said blocking means to receive granular silicon product discharged from said reaction chamber, and thereby dispense said silicon product from said reactor.
A preferred embodiment of the invention is also a 5 device for maintaining the purity of a high purity solid product during transfer of said solid product from a high purity zone, said device comprising:
solids blocking means for collecting said product, said blocking means having surfaces for contacting said 10 product, said surfaces being formed of a material noncontaminating to said product, said blocking means being operable to discharge said product therefrom; and valve means for discharging said product from said collection means, said valve means being operable between 15 a gastight closed position and an open position to receive therethrough the discharge from said blocking means and thereby dispense said product.
A preferred embodiment of the invention is also an angle of repose valve for dispensing high purity solids 20 from a protective environment, said valve comprising:
a housing having a top inlet and a bottom outlet;
an inlet tube sealingly disposed in said top inlet for receiving a flow of high purity solids from said protective environment, said inlet tube having a 25 noncontaminating interior for contacting said solids;
high purity solids blocking means for controlling said flow of high purity solids, said blocking means being disposed within said housing and blocking but not contacting said inlet tube, said blocking means having noncontaminating surfaces for contacting said solids, said blocking means being movable within said housing between a first position to receive and block said high purity solids and accumulate solids in said inlet tube and a second position to unblock and discharge said high purity solids to said bottom outlet; and means for moving said blocking means between said first position and said second position, said moving means being controllable from outside said housing.
In one preferred embodiment, the invention is an apparatus for maintaining the purity of a granular solid product during discharge from a storage vessel, said apparatus including:
(a) a vessel adapted to store granular solid product;
(b) a receiving vessel below said adapted vessel to receive said granular solid product;
20(c) passage means forming a fluid connection between said vessel and said receiving vessel;
(d) noncontaminating nongastight solids blocking means in said passage means; and (e) gastight valve means in said passage means 25between said nongastight solids blocking means and said storage vessel 132333~
whereby said gastight valve means can be opened and closed without errosion caused by the passage of said granular solid product through said gastight valve means during opening and closing thereby prolonging the 5 gastight life of said gastight valve and avoiding contamination of said solid product.
The solid products (solids) of the invention include all solids which are comprised of a large number of particles, granules, hunks, lumps, bits fragments, shreddings, slivers, pieces, chunks, BB's, and other moieties to make up a bulk.
According to the invention, a vessel may be considered to include a gastight valve and a solids-tight valve for dispensing product in a noncontaminating manner.
The invention may be generally described by reference to Figure 11. A container vessel 106 such as a seed particle bin, fluidized bed reactor or storage tank contains high purity solid product. The vessel 106 fluidly communicates through conduit 108 to a means 110 for alternately blocking and permitting the flow of high purity solids. The high purity solids may be transferred from the blocking means 110 through second fluid communi-cation means 112 for bulk collection in a hopper 114 or other device by transfer through a gastight valve 116.
25 Preferably, the gastight valve 116 is positioned and constructed such that high purity product passes through it without touching valve 116. Operation of the above-described apparatus permits preservation of the high purity solid in a controlled environment without con-tacting a gastight valve which could contaminate the solid and erode the valve.
In a preferred embodiment of the invention a non-contaminating means or means for avoiding valve wear is provided by a series of plates assembled as shown in Figure 1 to form a gas operated angle of repose valve 10 10 which may be threadably or otherwise connected to a noncontaminating (silicon carbide-coated graphite or silicon) tube 12 from which it receives solids such as a granular product. An end plate 18 of this assembly is shown in Figure 2. Another end plate 18 also threadably 15 or otherwise connects to a dispensing tube 14. Two next-to-end plates 16, (Fi~ure 4) are oriented in the opposite directions and placed adjacent the end plates 18 in the assembly 10. Two next-to-center plates 20 shown in Figure 5 are oriented opposite each other and placed 20 adjacent each of the next-to-end plates 16 in the assembly 10 such that the openings between the adjacent plates 16 and 20 are aligned. Finally, the center plate 22 is placed between the next-to-center plates 20 to form the serpentine flow path shown in Figure 1. Granular 25 product or similar solids entering tube 12 from above will accumulate somewhat in the space 24 of center plate 13233~
22 and build up in the space 26 of the top next-to-center plate 20 as well as in space 28 of the top next-to-end plate 16, the space 29 of end plate 18, and the inside of __ __ _ tube 12.
Thus the assembly 10 provides an angle of repose valve which operates by simply providing a horizontal blocking surface below tube 12 carrying solids downward.
The horizontal blocking surface, in this case surface 30 of bottom next-to-center plate 20 is wide enough that solids falling from above form a pile on it with a sloping surface angle e~ual to the angle of repose of the solids.
That is, without motive force, the solids falling on surface 30 do not tend to fall down into opening 26 of bottom next-to-center plate 20 but rather tend to accu-mulate as described. Since the solids cannot flow outtube 14 they are blocked and accumulate up into tube 12 and above until a motive force is applied to transfer the solids from surface 30 thereby unblocking the solids flow.
In the assembly 10 shown in Figure 1, the motive force may be applied by movement of the entire assembly, or other means such as the motion of a noncontaminating gas provided into gas inlet 32. The entire assembly 10 of Figure 1 may be made of any noncontaminating material suitable for handling the pure product entering tube 12.
Preferably, the inside diameter surface 34 of tube 12 and the remaining interior surfaces of the assembly which see 1~23339 the pure product, eithex while flow is stopped or during flow, are formed of the same material as the pure product or a composition including that material.
An angle of repose valve is particularly advanta-5 geous for the invention since a relatively small devicemay be used to accumulate solids product when used in conjunction with a tube or other container above the valve mechanism.
In a preferred embodiment of the invention, the lO high purity product is granular or BB-shaped silicon entering tube 12 and reposing on surface 30 and there-above until moved such as by entry of argon, helium, or other gas through inlet 32. The angle of repose valve thus blocks the flow of solids and fluid bed from the [vessel] fluidized bed reactor above the angle of repose valve. In such embodiment, the interior surfaces 34 and other interior surfaces of the assembly are preferably made of silicon, silicon carbide, silicon nitride, sialon (materials where the structural units are (SiAl) (O,N)4 20 or (Si,M) (O,N)4 tetrahedrawhere M is a metal), or another composition/alloy of silicon. Alternatively, the interior could be formed or coated with a noncontaminat-ing glass, quartz, or silicon carbide-coated graphite.
Alternatively, the entire assembly may be made of silicon 25 carbide-coated graphite, silicon carbide, silicon nitride, or preferably, high purity silicon. In still another embodiment the surfaces which could contact silicon are coated by plasma-sprayed silicon on the steel or other metal.
The entire assembly 10 of Figure 1 is suitably 5 disposed within an apparatus 36 shown in cross section in Figures 7 and 8. Each of the member plates, 16, 18, 20, and 22 has a dowel hole 38 (two dowel holes and dowels may be used). The plates are assembled so that each of the dowel holes _ are in line and the entire assembly lO may then be fitted into the apparatus 36 such that screw rod 40 received in the dowel holes 38 to maintain the rigid integrity of the assembly 10. A controlled supply of motive gas is connected to inlet tube 42 which is inserted through the interior wall 44 of apparatus 36 15 such that the inlet tube 42 projects into inlet 32 of the assembly 10.
In the above-described fashion, the noncontaminat-ing internal assembly 10 may be positioned within an apparatus 36 made of any suitable material such as steel, 20 stainless steel, or another metal. The exterior threaded wall 46 of tube 12 (Figure 1) and threaded wall 48 of tube 14 are threadably received within the threaded opening 50 of plate 52 (Figure 7) and threaded opening 54 of plate 56, respectively, in the apparatus 36 of Figure 25 7.
A sectional top view of the apparatus 36, taken just above the level of the inlet tube 42 but showing 13233~
plate 56 is shown in Figure 8. As can be seen, the entire apparatus 36 may be secured to the remainder of the flow path for the solid products by means of bolts or screws secured into threaded holes 58. Additionally, 5 bolts may be attached through a series OL holes 60 at the ends of plates 52 and 56 to secure the apparatus 36 tightly and make a gastight o-ring seal at 61.
Two alternative embodiments of the invention are shown in Figures 6 and 6a. Figure 6 shows a flapper style angle of repose valve 68 in the closed position with solid product 62 accumulated in the metal valve seat support 64 and accumulated in and above tube 66. The interior surfaces of tube 66 and metal valve seat support 64 which contacts solid product 62 are coated with a 15 noncontaminating material according to the nature of the solid product 62.
In the case of granular silicon product, e.g., the interior surfaces of tube 66 and support 64 are formed of silicon carbide-coated graphite, silicon carbide, silicon 20 nitride, sialon, silicon, or other noncontaminating material, preferably high purity silicon. The angle of repose valve 68 is operated so as to allow a buildup of solid product on a surface of support 64 and in tube 66 or a vessel above the valve~ When the valve 68 is 25 opened, solid product flows by gravity from above the valve. The product is collected not only immediately 13233~9 above the valve but in any tube or vessel above the valve before dispensing the product to a hopper or other container through a gastight valve (not shown) which may or may not be coated with or formed from noncontaminating materials. When valve 68 is used below a fluidized bed of solid product, the bed acts as a fluid such that if valve 68 remains open after accumulated solids are dis-pensed, then fluidized particles from the bed also begin to flow through valve 68. After the solid product 62 is collected in and above the valve 68, a gastight valve below the angle of repose valve 68 is opened and the collected solid product 62 is discharged from the valve seat support 64 by mechanically rotating handle 70 to discharge the collected silicon product 62 from the noncontaminating surfaces where the product 62 rests and above that position through the now opened gastight dispensing valve for collection, hoppering, packaging, or further processing.
If the angle of repose valve 68 shown in Figure 6 20 or other apparatus of the invention is operated in a pressurized environment which contains a dangerous gas, it is advisable to discharge the silicon product from the angle of repose valve through the open gastight valve and into a hopper or similar container which is sealed from the outside and pressure equalized with the pressurized environment. For example, if the solid product is 13233~9 granular silicon formed from silane or a silane com-position, this procedure will prevent the pyrophoric silane gas from escaping to the atmosphere. After the gastight valve below the angle of repose valve is again 5 closed, the hopper apparatus may be purged or otherwise made safe by appropriate techniques. The entire valve 68 may be contained within a housing 71 which may be constructed of any suitable material.
A schematic view of another angle of repose valve 10 72 is shown in Figure 6A. The solid product tends to accumulate at its natural angle of repose on surface 74 and build up in and above collection tube _6 as shown.
The angle of repose valve 72 of Figure 6A may be operated in much the same fashion as the angle of repose valve 16 15 shown in Figure 1. A motive gas is used to move the solid product 84 from the surface 74 and from within collection tube 76 into a hopper 78. This is accom-plished by opening gastight valve 80 and discharging a preferably noncontaminating motive gas through inlet 20 valve 82 to move the solid product 84 through the lower portion of tube 76, through the open gastight valve 80 and into hopper 78. That is, the dispensed product may free fall in a contacting or, preferably, noncontacting manner to a collection hopper. In one preferred embodi-25 ment, the opening of the gastight valve is larger thanand surrounds the tube through which solids flow. Of course it is always possible that some contact will occur between the open gastight valve and the solid product but this can be minimized by making the open I.D. of the gastight valve much larger than the drop tube 85. The resulting small amount of contact does not significantly contribute to contamination or valve wear. The invention is also advantageous because the solids do not contact the gastight valve during its operation.
After the desired amount of solid product 84 has 10 been transferred to hopper 78, inlet valve 82 is closed causing solid product 84 to again accumulate on surface 74 to close the angle of repose valve. When gastight valve 80 clears of solids it is then closed.
Referring to Figure 9, and Figure 10, the angle of repose valve 86 permits collection of silicon product in a cylinder 88 in such a fashion that solid product collects in cylinder 88 and builds up inside and above collection and entry tube ~0 thereby closing valve 86.
Preferably, the inside surfaces 92 of cylinder 88 and 94 of tube 90 are coated with or formed of a material which is noncontaminating to the entering high purity solid product. Cylinder 88 has formed in its wall a hole 96 which, when the cylinder 88 is in the open position shown in Figure 9, permits solid product to flow from the cylinder 88 and, in fact, directly from tube 90 through hole 96 into dispensing tube 98 and through an open gas-tight valve (not shown) for collection of product.
Preferably, all of the inside surfaces of the angle of repose valve 86 shown in Figure 9 which surfaces come into contact with the high purity solid product are coated with or formed of a material noncontaminating to the solid product. To close valve 86 rod 100 is rotated to move the cylinder 88 from the open position shown in Figure 9 to a closed position wherein the hole 96 is above the bottom inside horizontal surface of entry tube 90 such that the solids falling from the tube 90 above 10 form a pile on the cylinder inside wall with a sloping surface angle equal to the angle of repose of the solids. Of course, eventually the solids build up into the tube 90 in a manner according to the shape, size, and particle size distribution of the solid product thereby 15 preventing the solid product from flowing out hole 96 above the pile of solids. Thus the solids become blocked and begin to collect in tube 90 until the angle of repose valve 86 is opened by turning rod 100 to discharge the collected high purity product from the cylinder 88 20 through hole 96 into tube 98 and, preferably, through an open gastight valve for collection.
Suitably, a casing 102, which may be made of any substance such as stainless steel, carbon steel, or other material encloses the angle of respose valve 86 to 25 maintain a high purity zone or environment. The high purity zone or environment may be associated with a 13~3339 - 27. -gastight or even a pressurized zone open to the solids inthe angle of repose valve 86 since the valve is not gastight.
As may be seen in Figure 9, the cylinder 88 has a 5 cutout arcuate slot 105 formed along surface 104 which may be seen in phantom and perspective in Figure 10.
This slot _05 permits rotation of cylinder 88 without_ interference with tube 90. Rod lO0 is sealingly engaged on bearings in casing 102 so that the high purity zone, 10 gastight zone, or pressurized zone, as the case may be, is maintained. The integrity of the zone is maintained during collection of product in cylinder 88 by keeping a gastight valve (not shown) below tube 98 in the closed position.
The assembly shown for the cylinder 88 and rod lO0 may be formed in the manner shown in Figures 9 and 10 or in any convenient mechanical arrangement to effect the purposes of the invention as shown in this embodiment such that solid product may be collected and then 20 discharged from cylinder 88. Of course, the angle of repose valve 86 may be considered to include tube 90 since solid product builds up within this tube due to the angle of repose of the solid product on the surface of cylinder 88.
The embodiment of angle of repose valve 86 shown in Figures 9 and 10 is advantageous over angle of repose 132333~
valve 68 shown in Figure 6 in that dust and small particles of product associated with the bulk solids may escape from the valve seat support 64 due to turbulence around the bottom of tube 66. Valve 86, when in its 5 closed position, very nearly seals arcuate surface 104 around the bottom of tube 90, thereby preventing product from gaining entry into the closed space in casing 102 which entry would permit contamination. If product is inadvertently blown out of seat 64 in Figure 6, it can 10 accumulate on the closed gastight valve below to cause wear when the valve is opened and permit further contamination.
Having described our invention, one skilled in the art could ascertain various changes and modifications 15 thereof which are within the scope of the disclosed apparatus and process. Thus the invention is limited only by the lawful scope of the following claims:
Claims (15)
1. An angle of repose valve for dispensing high purity solids from a protective environment, said valve comprising:
a) a housing having a top inlet and a bottom outlet;
b) an inlet tube sealingly disposed in said top inlet for receiving a flow of high purity solids from the protective environment, the inlet tube having an interior which in non-contaminating to the high purity solids for contacting the high purity solids;
c) high purity solids blocking means for controlling the flow of high purity solids, the blocking means being disposed within the housing and blocking but not contacting the inlet tube, the blocking means having surfaces which are non-contaminating to the high purity solids for contacting the solids, the blocking means being moveable within the housing between a first position to receive and block the high purity solids and accumulate solids in the inlet tube and a second position to unblock and discharge the high purity solids to the bottom outlet, the blocking means being cylindrical in shape, having a horizontally disposed cylindrical axis, the inlet tube extending into the interior of the cylindrically shaped blocking means, the blocking means having a wall having a hole formed therein for discharging solids when the blocking means is in the second position, the cylindrical shaped blocking means being rotatable on its cylindrical axis to move between the first position and the second position; and d) means for moving the blocking means between the first position and the second position, the moving means being controllable from outside the housing.
a) a housing having a top inlet and a bottom outlet;
b) an inlet tube sealingly disposed in said top inlet for receiving a flow of high purity solids from the protective environment, the inlet tube having an interior which in non-contaminating to the high purity solids for contacting the high purity solids;
c) high purity solids blocking means for controlling the flow of high purity solids, the blocking means being disposed within the housing and blocking but not contacting the inlet tube, the blocking means having surfaces which are non-contaminating to the high purity solids for contacting the solids, the blocking means being moveable within the housing between a first position to receive and block the high purity solids and accumulate solids in the inlet tube and a second position to unblock and discharge the high purity solids to the bottom outlet, the blocking means being cylindrical in shape, having a horizontally disposed cylindrical axis, the inlet tube extending into the interior of the cylindrically shaped blocking means, the blocking means having a wall having a hole formed therein for discharging solids when the blocking means is in the second position, the cylindrical shaped blocking means being rotatable on its cylindrical axis to move between the first position and the second position; and d) means for moving the blocking means between the first position and the second position, the moving means being controllable from outside the housing.
2. The angle of repose valve of Claim 1 wherein the high purity solids are particulate polysilicon.
3. The angle of repose valve of Claim 1 wherein the surfaces which are non-contaminating to the high purity solids comprises surfaces of silicon or a silicon-containing composition.
4. The angle of repose valve of Claim 3 wherein the surfaces are silicon carbide, silicon nitride, sialon or a silicon-aluminum-oxynitride.
5. An angle of repose valve for dispensing high purity solids from a protective environment consisting essentially of:
a) a housing having a top inlet and a bottom outlet;
b) an inlet tube sealingly disposed in the top inlet for receiving a flow of high purity solids from the protective environment, the inlet tube having an interior which is non-contaminating to the high purity solids for contacting the solids;
c) a cylinder having solids inlet means and a bottom, inside, horizontal surface for accumulating solids thereon, the inlet tube extending into the interior of the cylinder; and d) means for rotating the cylinder to discharge the solids from the horizontal surface.
a) a housing having a top inlet and a bottom outlet;
b) an inlet tube sealingly disposed in the top inlet for receiving a flow of high purity solids from the protective environment, the inlet tube having an interior which is non-contaminating to the high purity solids for contacting the solids;
c) a cylinder having solids inlet means and a bottom, inside, horizontal surface for accumulating solids thereon, the inlet tube extending into the interior of the cylinder; and d) means for rotating the cylinder to discharge the solids from the horizontal surface.
6. The angle of repose valve of Claim 5 wherein the high purity solids are particulate polysilicon.
7. The angle of repose valve of Claim 5 wherein the interior which is non-contaminating to the high purity solids comprises surfaces of silicon or a silicon-containing composition.
8. The angle of repose valve of Claim 7 wherein the silicon-containing composition is silicon carbide, silicon nitride, sialon or a silicon-aluminum-oxynitride.
9. The angle of repose valve of Claim 5 in which the cylinder having solids inlet means and a bottom, inside, horizontal surface for accumulating solids thereon further comprises a material which is non-contaminating to the high purity solids.
10. The angle of repose valve of Claim 9 wherein the material which is non-contaminating to the high purity solids is silicon, silicon carbide, silicon nitride or a silicon-aluminum-oxynitride.
11. An angle of repose valve for dispensing high purity solids from a protective environment, the valve comprising:
a) a housing having a top inlet for receipt into the housing of the high purity solids and a bottom outlet for discharging from the housing the high purity solids;
b) a flow path between the top inlet and the bottom outlet, the path having (i) a blocking surface portion upon which high purity solids can be supported so as to obtain their natural angle of repose whereby a seal against flow is formed in the path;
(ii) a first downwardly disposed portion extending from the top inlet to a point in flow communication with the blocking surface portion, and (iii) a second downwardly disposed portion extending from a point in flow communication with the blocking surface portion to the bottom outlet; and c) a means for opening the path to the flow of high purity solids therethrough by directing a motive gas across the blocking surface so as to move, in the same direction, those high purity solids which have formed the seal or which would form such a seal if not so moved.
a) a housing having a top inlet for receipt into the housing of the high purity solids and a bottom outlet for discharging from the housing the high purity solids;
b) a flow path between the top inlet and the bottom outlet, the path having (i) a blocking surface portion upon which high purity solids can be supported so as to obtain their natural angle of repose whereby a seal against flow is formed in the path;
(ii) a first downwardly disposed portion extending from the top inlet to a point in flow communication with the blocking surface portion, and (iii) a second downwardly disposed portion extending from a point in flow communication with the blocking surface portion to the bottom outlet; and c) a means for opening the path to the flow of high purity solids therethrough by directing a motive gas across the blocking surface so as to move, in the same direction, those high purity solids which have formed the seal or which would form such a seal if not so moved.
12. An angle of repose valve of Claim 11 wherein the path has an interior surface which is non-contaminating to the high purity solid.
13. The angle of repose valve of Claim 13 wherein the high purity solid is polysilicon.
14. An angle of repose valve as in Claim 13 wherein the interior surface is made of one of silicon, silicon carbide, silicon nitride, sialon, and another composition/alloy of silicon.
15. An angle of repose valve as in Claim 13 wherein the interior surface is one of a non-contaminating glass, quartz, and silicon carbide-coated graphite.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US76143485A | 1985-08-01 | 1985-08-01 | |
| US761,434 | 1985-08-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1323339C true CA1323339C (en) | 1993-10-19 |
Family
ID=25062172
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 514570 Expired - Fee Related CA1323339C (en) | 1985-08-01 | 1986-07-24 | Valve system |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS62110098A (en) |
| CA (1) | CA1323339C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101419143B1 (en) * | 2009-10-09 | 2014-07-11 | 신닛테츠스미킨 카부시키카이샤 | Gate valve |
-
1986
- 1986-07-24 CA CA 514570 patent/CA1323339C/en not_active Expired - Fee Related
- 1986-08-01 JP JP18182786A patent/JPS62110098A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62110098A (en) | 1987-05-21 |
| JPH0567512B2 (en) | 1993-09-27 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |