US3706652A

US3706652A - Separable plasma torch apparatus

Info

Publication number: US3706652A
Application number: US80691A
Authority: US
Inventors: Stephen Mark Lesley Hamblyn; Anthony Patrick Money; Ian Malcolm Mackinnon; John Edmund Trotter
Original assignee: United States Borax and Chemical Corp
Current assignee: US Borax Inc
Priority date: 1970-05-20
Filing date: 1970-10-14
Publication date: 1972-12-19
Anticipated expiration: 1989-12-19
Also published as: CA937397A

Abstract

Plasma torch apparatus having separable parts such as separable inlet head and/or feed device. Preferably the head and base are made of brass.

Description

L A N Y L B M A H L M.

SEPARABLE PLASMA TORCH APPARATUS 2 Sheets-Sheet l Filed Oct. 14, 1970 19, 1972 s. M. l.. HAMBLYN ETAL 3,706,652

SEPARABLE PLASMA TORCH APPARATUS 2 Sheets-Sheet 2 Filed Oct. 14, 1970 STPA/EN M10/@K [5167 #f4/W62 //V ANTHONY PA TfQ/C/ MOA/5V JAN MAL COL/W M/QCA//NNON JOHN EDM/ND 79077-5? INVENTORS.

United States atent O 3,706,652 SEPARABLE PLASMA TORCH APPARATUS Stephen Mark Lesley Hamblyn, Long Ditton, Anthony Patrick Money, Surbiton, Ian Malcolm Mackinnon, Kingston-upon-Thames, and John Edmund Trotter, Hampton, England, assignors to United States Borax & Chemical Corporation, Los Angeles, Calif.

Filed Oct. 14, 1970, Ser. No. 80,691 Claims priority, application Great Britain, May 20, 1970, 24,495/ 70 Int. Cl. B01k 1/00 U.S. Cl. 204-312 11 Claims ABSTRACT OF THE DISCLOSURE Plasma torch apparatus having separable parts such as separable inlet head and/or feed device. Preferably the head and base are made of brass.

This invention relates to an improved apparatus for effecting a hightemperature chemical reaction, namely a plasma torch.

In co-pending application Ser. INo. 737,464, liled June 17, 1968, by H. D. Murdoch and S. M. L. Hamblyn, now Pat. No. 3,625,846 issued Dec. 7, 1971, there is described a process for carrying out a high-temperature chemical reaction, such as between boron trichloride and hydrogen, to produce nely divided elemental boron, in which one gaseous reactant is ionized by induction heating to form a plasma and another generally gaseous reactant is fed into the plasma as that reaction takes place. In that application there is also described an apparatus for use in the process which in essence is a quartz tube surrounded by an induction coil, having an inlet upstream of the coil for the gas to be ionized and having a number of quartz tubular inlets downstream of the coil through which the second reactant is introduced to the plasma.

In a related co-pending application Ser. No. 1,195, led Jan. 7, 1970, by S. M. L. Hamblyn, A. P. Money, and I. M. Mackinnon, is described an improved apparatus according to said earlier application, which is provided with a jacket through which a fluid cooling medium may be passed.

We have now devised a novel plasma torch which is an improvement in the torch described in the aboveidentified copending applications.

According to the present invention, the plasma torch comprises a quartz tube which is surrounded by an induction coil and within which a plasma is formed as gases pass along the tube, an inlet device for gas upstream of the coil, and a feed device for reactant downstream of the coil, either the inlet device or the feed device or, preferably, both being an element removably attached to the tube.

Thus if supply tubes for plasma forming gas or for reactant to the reaction tubes are damaged, they can be more readily replaced. This construction of separable parts facilitates access to the reaction tube for cleaning.

Preferably each removable element is made of a material stronger than quartz which is not heated by electromagnetic induction; the preferred such material being brass. Thus, the apparatus comprises as separable elements, a gas inlet head, a reaction tube, and a reactant feed device.

The inlet device is suitably a cylindrical head of a strong, para-magnetic material such as brass, having substantially the same radial cross-section as the reaction tube, closed at one end by an integral cap, and bored to provide at least one tangential entry port for gas. Its open end can then be compressively urged into sealing Patented Dec. 19, 1972 ICC contact, e.g., through a compressible seal member with the upstream end of the reaction tube. The head can be provided with an integral cooling jacket.

The feed device is suitably an annular element of strong, para-magnetic material such as brass, of internal crosssection substantially the same as the radial cross-section of the reaction tube. This too can be compressively urged into sealing contact with the open downstream end of the reaction tube. This annular element is bored to provide at least one inlet passage for reactant, and preferably has a number of such passage circumferentially spaced and radially inwardly directed. There can be more than o ne such annular element, for the'entries of different reactants. They or each annular element can be provided with passages for coolant, either by having an integral jacket or, preferably, by the presence of a cooling passage formed in the solid material from which the annular element is shaped.

A plasma torch according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. l shows a longitudinal section through a plasma torch, the components being shown detached from each other in position for assembly;

FIG. 2 shows a transverse section of a head of the torch taken along A-A1;

FIG. 3 shows a plan, viewed from upstream, of the rst base; and

FIG. 4 shows a plan, also viewed from upstream, of the second base.

In FIG. l there is shown a cylindrical quartz reaction tube 10 which is surrounded by a cylindrical quartz jacket 11 joined to the reaction tube by a flange 12 which extends radially outwardly from the downstream end of the reaction tube. Interposed between the reaction tube and the jacket is a cylindrical quartz battle 13, extending upstream beyond the jacket and downstream substantially to the flange. The bal-lie is joined circumferentially to the reaction tube at the upstream end 14 and the jacket is joined circumferentially to the bafiie at the upstream end 15. The jacket has near its upstream end a conduit 16 for the admission of coolant water to the cooling channel 17 formed between the jacket and barile; and the baie has near its upstream end a conduit 18 for the exit of coolant water from a cooling channel 17A formed between the baille and the reaction tube, the two cooling channels being in communication at their downstream ends. The tube assembly of reaction tube, bai-lle and jacket is surrounded by a radio frequency induction coil 19. In the position of operation the coil is xed in an operating bay (not shown) and the tube assembly can be slid into the coil or removed therefrom as necessary.

A gas injection head, indicated generally at 20, is provided to mate with the upstream end .14 of the reaction tube. An inner cylindrical brass member 21 of the head, substantially the same diameter as tube 10, is provided with a flange 22 which extends radially outwardly at its downstream end and with a brass disc 23 which closes its upstream end. Four gas inlet ports 24, equally spaced from the brass disc and equi-angularly disposed about the circumference of the inner member are formed in the inner member, being directed to admit gas substantially at a tangent to the interior of the head. A ange 25 is provided around the upstream end of the inner member below the inlet ports, the flange 25 extending radially outwardly from the inner member and being returned upstream of the brass disc. The Outer face 26 of the returned portion of the flange 25 is threaded to cooperate with a brass cap 27 which is apertured to receive a centrally located conduit 28 for gas and which, together with the inner member, disc and flange 25, detnes a manifold 29.

A cylindrical brass jacket 30 is welded to lflanges 22 and 25 and contains a downstream inlet port 31 and an upstream outlet port 32 for coolant water.

A base assembly, indicated generally at 33 and shown in detail in FIGS. 3 and 4 is provided to seat on the downstream end of the reaction tube. A brass annular base 34, having in its upstream surface a central recess 35 to provide a concentric circular housing for the tube assembly, contains a concentric circular manifold 36; manifold 36 communicates with the exterior of the base via two diametrically opposed tail gas inlets 37 and communicates with an internal passage 38 (which is aligned with the interior of tube via eight passages 39, which are equiangularly disposed about the inner circumference of the manifold and extend radially inward from the manifold, being cranked to enter passage 38 at discharge port 40, directed towards the head at an angle to the axis of the tube. The base also contains upstream a concentric circular duct 41 into which an inlet passage 42 and a diametrically opposed outlet passage 43 pass; duct 41 is used as a cooling channel.

Base 34 is, in turn, on a second brass annular base 44 which contains a downstream concentric circular manifold 45 communicating with two diametrically opposed secondary tail gas inlets 46 and leading into a central annular orifice 47 by means of eight passages 48, equiangularly disposed about the inner circumference of the manifold and extending radially inward from the manifold, being cranked to enter the orice at discharge port 49, directed towards the head at an angle to the axis of the tube. The second base also contains four solids feed pipes 50, each leading from the periphery of the base to the annular orifice and being equi-angularly disposed about the circumference of an annular orifice.

To assemble the apparatus of this invention, ring 34 is urged against ring 44 in the position shown in FIG. l with gasket 51 interposed, while ring 44 is in alignment with a conduit for the removal and cleaning of gases. Tube 10l with its associated water jackets is similarly urged against ring 33, being received within recess 35 and spaced from the ring by the gasket 52, and the head is urged in the position shown in FIG. l against the upstream end of tube lil, a gas-tight seal being formed by the interposed O-ring 53. The assembled apparatus is held in position by clamps which urge head 10 against ring 44.

In use of the apparatus, gas to be ionised, such as an argon-hydrogen mixture, is delivered through inlet 28 into head 20` and then passes through the tube 10, being ionised to form a plasma when passing through the tube within RF coil 19. A reactant to be reacted with the plasma is fed into the downstream end of the plasma through one or both of the rings 34, 44. For example, boron trichloride gas can be fed through inlet 37 or through inlet 46. If it is desired to react a solid reactant, this is suitably delivered through inlet 50. One can, for example, make elemental cobalt by blowing cobalt chloride (III) as a solid powder suspended in argon gas into a hydrogen plasma. The operation of a chemical process in apparatus of the sort described in the present application is more fully described in our co-pending application No. 737,464 or British Pat. 1,194,415.

In a typical run Nickel (II) chloride in a stream of boron trichloride (1:2 molar ratio) is passed through inlets 50 of the ring at a rate of 27 g./min. Hydrogen s passed through inlet 28 of the .ring ata rate of 40 liters per minute. The resultant product is nickel boride. The reaction is particularly good if the nickel chloride has a particle size of 60 microns or less.

During use of the apparatus it is cooled by passage of a refrigerant, e.g. water, through cooling channels 32, or 18, or 411. The product of the reaction is deposited on the walls of the apparatus as a ne powder, or may be carried by unreacted gases out of the apparatus into the removal conduit and thence to separation apparatus such as a bagiilter after which the gases are Washed. Being made of separable parts the apparatus can readily be undone to permit removal of deposited powder product and to permit cleaning. The apparatus is stronger than quartz so there is less ranger of damage to the coolant tubes or to the inlet means for reactant, and if there is damage then the damaged detachable part can be replaced without having to replace the entire apparatus.

Various changes and modifications of the invention can be made and, to the extent that such variations incorporate the spirit of this invention, they are intended to be included within the scope of the appended claims.

What is claimed is:

1. A plasma torch apparatus comprising a quartz tube adapted for forming a plasma as gases pass along within said tube, an induction coil surrounding said quartz tube, an inlet device for gas removably attached to said quartz tube upstream of said induction coil, and means for feeding reactant attached to said quartz tube downstream of said induction coil, said inlet device comprising a cylindrical head made of a para-magnetic material, having substantially the same radial cross-section as said quartz tube, an integral cap enclosing one end thereof, the opposite end being compressively urged into sealing contact with the upstream end of said quartz tube, said head being provided with at least one tangential entry port for gas.

2. A torch apparatus of claim 1 in which said means for feeding reactant is removably attached to said quartz tube.

3. The plasma apparatus according to claim 1 wherein said head is provided with four entry ports equi-angularly spaced in said cylindrical head, said entry ports cornmunicating with a chamber defined by the closed end of said cylindrical head and a cap surrounding the closed end, said cap having a conduit for gas.

4. The torch apparatus according to claim 2 in which both said inlet device and said means for feeding reactant are made of brass.

5.. The apparatus according to claim 1 in which said para-magnetic material is brass.

6. The apparatus according to claim 1 in which said cylindrical head is surrounded by an integral cooling jacket.

7. The apparatus according to claim 2 in which said means for feeding reactant comprises an annular element of para-magnetic material having an internal cross-section substantially the same as the radial cross-section of said quartz tube and having at least one inlet passage for reactant, said reactant feeding means being compressively urged into sealing contact with the downstream end of said quartz tube.

8. The apparatus according to claim 7 in which said para-magnetic material is brass.

9. The apparatus according to claim 7 in which said inlet passage for reactant comprises more than one radially inwardly directed passages circumferentially spaced in said means for feeding reactant.

|10. The apparatus according to claim 7 in which said annular element is provided with passages for coolant.

11. The apparatus according to claim 9 in which said means for feeding reactant is a base assembly comprising an upper and lower annular base in sealed relationship and being aligned with a conduit for removal and cleaning of gases.

References Cited UNITED STATES PATENTS 3,547,802 12/l97;0 Gleit et al. 204-312 3,345,280 lll/1967 `Berghaus 204-164 JOHN H. MACK, Primary Examiner T. TUFARIELLO, Assistant Examiner