# US 4,391,860 A · Device for the controlled feeding of powder material

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- Number: US 4,391,860 A
- Document ID: US4391860A
- Status: Granted
- Kind: A
- Application number: 06/237,092
- Filed: 1981-02-23
- Granted: 1983-07-05
- Earliest claimed: 1981-01-21
- Assignees: Eutectic Corporation
- Inventors: Anthony J. Rotolico; Eduardo Romero; John E. Lyons
- Web page: https://patentgrep.com/patent/US4391860A

## CPC

- B05B 7/1404: {Arrangements for supplying particulate material}
- B01J 8/001: {Controlling catalytic processes (B01J8/1809 takes precedence)}
- B01J 8/0015: {Feeding of the particles in the reactor; Evacuation of the particles out of the reactor}
- H05H 1/42: with provisions for introducing materials into the plasma, e.g. powder or liquid {(arc stabilising or constricting arrangements H05H1/3405; coaxial protecting fluids H05H1/341)}
- B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS

## Abstract

The invention contemplates a powder-feeding system for gas-propelled delivery of a powder to be controllably supplied, as to a flame-spraying gas torch or to a transferred-arc plasma torch. A fluidizing chamber receives (a) fluidizing-gas flow from below a porous screen, and (b) a restricted gravitational flow of powder at a relatively small central discharge location above the porous screen. A gas conduit extends transversely through the chamber between the powder-discharge location and the porous screen; it has a carrier-gas supply connection at one end and a gas-propelled powder-delivery connection at its other end. The conduit also has an upwardly extending opening virtually beneath and facing the powder-discharge location, but a shed interposed between this opening and the powder-discharge location sufficiently overlaps the opening to assure that no powder will pass through the opening and into the conduit unless it has been gas-fluidized. The powder-discharge flow is blocked to gas flow when powder is being delivered by the carrier-gas flow, but the powder delivery is terminated promptly upon gas-venting the fluidizing chamber, via the powder-discharge flow or otherwise. A multiple-unit combination of such a system is also described wherein the proportion of different gas-fluidized powders may be selectively varied and/or coordinated to achieve various different application objectives, as in the course of a single run of a flame-spraying torch served by such combination.

## Claims

### Claim 1

The method of supplying powder to a powder-deposition torch, which comprises selecting two powder-fluidizing systems each having the ability to selectively control the rate of its powder assimilation in a flow of carrier gas therethrough, supplying different gas-fluidizable powders to the respective systems, increasing the rate of powder assimilation in carrier-gas flow through one of said systems while decreasing the rate of powder assimilation in the carrier-gas flow through the other of said systems, combining the carrier-gas flows after powder-assimilation therein, and delivering the combined flow to the torch, the same carrier-gas flow being passed through the respective systems in succession, whereby the combining step occurs at passage of the carrier-gas flow through the second system.

### Claim 2 (depends on 1)

The method of claim 1, in which the increasing rate commences at zero.

### Claim 3 (depends on 1)

The method of claim 1, in which the decreasing rate is terminated at zero.

### Claim 4 (depends on 1)

The method of claim 1, and thereafter decreasing the rate of powder assimilation in carrier-gas flow through said one system, while increasing the rate of powder assimilation in carrier-gas flow through said other system, and while continuing delivery of the combined flow to the torch.

### Claim 5

The method of supplying powder to a powder-deposition torch, which comprises selecting two powder-fluidizing systems each having the ability to selectively control the rate of its powder assimilation in a flow of carrier gas therethrough, supplying different gas-fluidizable powders to the respective systems, varying the ratio of a powder-assimilation rate in carrier-gas flow through the respective systems, combining the carrier-gas flows after powder-assimilation therein, and delivering the combined flow to the torch, the same carrier-gas flow being passed through the respective systems in succession, whereby the combining step occurs at passage of the carrier-gas flow through the second system.

### Claim 6 (depends on 5)

The method of claim 5, wherein the sum of the respective powder-assimilation rates is maintained substantially constant.

### Claim 7 (depends on 1, 5)

The method of claim 1 or claim 5, in which the powder supplied to one of said systems is ceramic and the powder supplied to the other of said systems is metallic.

### Claim 8

The method of supplying powder to a powder-deposition torch, which comprises selecting two powder-fluidizing systems each having the ability to selectively control the rate of its powder assimilation in a flow of carrier gas therethrough, providing different supplies of the same powder to the respective systems, supplying the same single flow of carrier gas to both said systems in succsssion, varying the rate of powder assimilation in said single flow at one of said systems while varying in the opposite sense the rate of powder assimilation in said single flow at the other of said systems, the variation being from zero flow at one system and to zero flow at the other system, and delivering said single flow to the torch after passage through both systems.

### Claim 9

The method of supplying powder to a powder-deposition torch, which comprises selecting two powder-fluidizing systems each having the ability to selectively control the rate of its powder assimilation in a flow of carrier gas therethrough, supplying different gas-fluidizable powder to the respective systems, supplying the same single flow of carrier gas to both said systems in succession, varying the rate of powder assimilation in said single flow at one of said systems, and delivering said single flow to the torch after passage through both systems.

### Claim 10

Powder-feeding apparatus for carrier-gas delivery of a powder to be supplied to a torch or the like in loose particulate form, said apparatus comprising a carrier-gas line adapted at one end for connection to a source of carrier gas and adapted at its other end for connection to a torch or the like, and means for supplying a predetermined flow of carrier gas in said line, first and second powder-fluidizing chambers each having a fluidized-powder discharge-port connection to said line, said discharge-port connections being in succession in their connection to said line, a separate powder-supply means associated with each of the respective chambers, and a separate fluidizing-gas supply for each of said chambers, each fluidizing-gas supply being distinct and apart from the carrier-gas line and including a regulating valve connected to each of the respective chambers, whereby the setting of the respective regulator valves determines the respective rates of carrier-gas assimilation of the powders separately fluidized in the respective chambers.

### Claim 11 (depends on 10)

Apparatus according to claim 10, in which control means having concurrent connection to both regulator valves is operative to maintain a predetermined relation between regulator-valve settings.

### Claim 12 (depends on 10)

Apparatus according to claim 10, in which said relation is one of increasing fluidizing-gas flow to one of said chambers while decreasing fluidizing-gas flow to the other of said chambers.

### Claim 13 (depends on 11)

Apparatus according to claim 11, in which said relation is selected to produce a substantially constant combined delivery rate for both fluidized powders to said line.

### Claim 14 (depends on 10)

Apparatus according to claim 10, in which said line includes two branch lines for comingled delivery of separate carrier-gas flows in the respective branch lines, said first and second chambers being each associated with a different one of said branch lines.

### Claim 15 (depends on 10)

Apparatus according to claim 10, in which said line is a single carrier-gas line with which said first and second chambers are each associated.

### Claim 16 (depends on 15)

Apparatus according to claim 15, in which said first and second chambers are independently associated with said line in spaced succession in the direction of carrier-gas flow.

### Claim 17 (depends on 10)

Apparatus according to claim 10, in which said first and second chambers are part of a larger plurality of such chambers, and in which said line is a single carrier-gas line with which each of said chambers is independently associated.