US3825230A

US3825230A - Safe geometry nuclear fuel powder blender

Info

Publication number: US3825230A
Application number: US00250130A
Authority: US
Inventors: J Frye; R Morton
Original assignee: BOARDMAN CO
Current assignee: BOARDMAN CO
Priority date: 1972-05-04
Filing date: 1972-05-04
Publication date: 1974-07-23
Anticipated expiration: 1991-07-23

Abstract

A safe geometry nuclear fuel powder blender of a tumble type having unique and improved concepts of loading and unloading, powder mixing pins, access hatches, and drive means. The powder is fluidized by an appropriate gas and subjected to a rocking motion to facilitate flow to a discharge mechanism of a vacuum pickup or screw conveyor type. Structural integrity and safe and easy operating access hatches are provided.

Description

1 July 23,1974

2,514,375 7/1950 Cornell..............,.................. 259/89 SAFE GEOMETRY NUCLEAR FUEL POWDER BLENDER [75] Inventors: James A. Frye, Oklahoma City;

FOREIGN PATENTS OR APPLICATIONS 4/1965 Germany 259/3 Ralph B. Morton, Del City, both of Okla.

[73] Assignee: The Boardman Company,

Primary Examiner-Peter Feldman Oklahoma City, Okla. Assistant Examiner-Philip R. Coe May 4, 1972 [21] Appl. No.: 250,130

[22] Filed:

ABSTRACT A safe geometry nuclear fuel powder blender of a tumble type having unique and improved concepts of loading and unloading, powder mixing pins, access hatches, and drive means. The powder is fluidized by an appropriate gas and subjected to a rocking motion to facilitate flow to a discharge mechanism of a vacuum pickup or screw conveyor type. Structural integrity and safe and easy operating access hatches are provided.

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[56] References Cited UNITED STATES PATENTS 2,100,599 11/1937 Schulthess et 259/30 X 10 Claims, 10 Drawing Figures PATENTEDJULZSIBH SHEET 2 BF 3 BLEN DED

MATERIAL BLENDED MATERIAL AIR M SOURC i PATENIED JULZBIQM

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3 or 3 SAFE GEOMETRY NUCLEAR FUEL POWDER BLENDER BACKGROUND OF THE INVENTION v SUMMARY1OF THE INVENTION The present invention generally relates to a tumble type nuclear fuel powder blender and, more especially, to a design and method of loading and unloading the blender, design of mixing pins and access hatches, and

method of driving the unit. In one concept, unloading of the material after blending is performed pneumatically with dry air or inert gas which is injected into an air chamber surrounding the bottom half of the blender drum which functions to fluidi'ze the powder and, aided by a rocking motion, the material is caused to flow into a vacuum pickup for conveying to a subsequent station. A specifically different form of discharge includes a variable pitch screw conveyor, which permits greatly reducing rocking and vibration and injection of gas to substantially reduce problems of dusting and overpressure in the blender.

Mixing pins within the blending chamber serve structurally as stay bolts for structural integrity in the event of excessive pressure buildup and others of the pins act to prevent collapsing during a vacuum loading cycle.

A hatch construction is provided having features facilitating ease of manufacture, provision of a bimetallic construction and improved sealing and release characteristics.

Additional objects, advantages and features of the invention will be more readily apparent from the following detailed description of embodiments thereof when taken together with the accompanying drawings in which:

FIG. 1 is a front elevational view of an embodiment of the invention, including rotating drive means and a schematic illustration of air flotation and conveying means;

FIG. 2 is an enlarged, detailed vertical sectional view taken on line 22 of FIG. 1;

FIG. 3 is an enlarged, detailed, fragmentary sectional view along line 33 of FIG. 2;

FIG. 4 is an enlarged, fragmentaryvertical sectional view taken along line 44 of FIG. 3;

FIG. 5 is an enlarged, fragmentary sectional view taken along line 5-5- of FIG. 1, showing mounting of materialflotation implementing air pads;

FIG. 6 is a fragmentary sectional view of a single air pad and associated mechanism taken along line 6--6 of FIG. 3; V

FIG. 7 is an enlarged, fragmentary elevational view of anaccess hatch shown in FIG. 1;

FIG. 8 is a detailed vertical sectional view taken along line 8-8 of FIG. 7, disclosing pivoting and locking means for the hatch;

FIG. 9 is a fragmentary elevational view of a modified form of material discharge means; and

FIG. 10 is a view similar to FIG. 9 of a still further modification of discharge and measured collecting means for blended powder.

Referring now in greater detail to the drawings, the tumble type nuclear fuel powder blender of the invention generally designated 10 includes a substantially circular drum 12 to which is affixed a removable cover 14 by means of bolts and nuts 16 peripherally arranged and spaced thereabout. The design of the blender as shown and described herein was especially devised for a 5 inch maximum thickness mixing chamber and size ranging including various diameter units of, for example, 2 feet, 4 feet, 6 feet, 9 feet and 12 feet. The drum is rotatably mounted on a base generally designated 18 by means of shaft 20 joumalled in pillow block 22, and a driven sprocket 24 operatively attached to the drum 12. A reinforcing gusset 26 interengages hub 28 and sprocket 24. A variable speed electric motor 30, with reverse drive for rocking motion, is operatively engaged with sprocket 24 by drive chain 32 in association with an idler gear 34. While particularly adapted to impart a rocking motion to the blender to facilitate material flow to a discharge, the drive is such that the drum can be rotated as desired and as indicated by arrow 36.

The drum of the FIG. 1 embodiment is provided with a discharge spout 38 opening into a discharge hopper 40 which will be described in greater detail hereinafter. Removable cover 14 is provided with a plurality of access hatches 42 spaced therearound, the details of which will be described with reference to FIGS. 7 and 8 and these hatches provide ready access to various portions of the blending chamber. A suitable number of mixing pins 44 are provided interiorally of the blending chamber and optionally can be welded in place to the interior of the removable cover or replaceable and sealed with an O-ring. A suitable number of the mixing pins can also act as stay bolts for structural integrity in the event of excessive pressure buildup. Others of the pins act to prevent collapsing of the removable cover during a vacuum loading cycle. These pins are spaced around the inner periphery of the blending chamber, or in such other areas as might be indicated, to insure optimum blending of material as the drum rotates during the blending cycle as indicated by arrow 36 in FIG. 1.

As shown in FIGS. 7 and 8, the access hatches 42 are conical for a tapered fit with a captured O-ringseal 46. The hatch is made in two parts divided along the parting line of the O-ring seating groove 47 for ease of manufacture and to provide bi-metallic construction. The relatively thin inner disc 48 is stainless steel for contact with the powder, while the outer disc 50 is of mild steel and is thicker for strength. The tapered seat improves opening into the blending chamber and, additionally, a nozzle 66 is provided to facilitate a vacuum hookup and also a vent for excessive fluidizing gas. Unloading is performed in the embodiment of FIG. 1 pneumatically with dry air or inert gas such as nitrogen being injected into an air chamber 68 which serves as an air pad compartment and in the nature of a plenum chamber. The construction of the air pads can be as shown in FIG. 6 wherein a coupling half 70 is secured to and opening into the interior of the drum with pad inserts or nozzles 72 having bores 74 therethrough threadedly engaged in the coupling half. Micron filters 76 are positioned in the bores by snap rings 78. Air from air source 80 passes into and through the nozzles and exits into the interior of the blender drum as indicated by arrows 82 with the flow schematically depicted at 82A. As shown in FIG. 5, the nozzles are provided in the pads 72 around the lower half of the drum as a plurality of individualized pads including each of a plurality of individual nozzles with air interconnections to the source passing through a closure plate 84 for the chamber. Preferably, the dry air pads are valved with quick disconnect couplings. The number of nozzles in each pad are selected for optimal operation and upon injection of air therethrough into the interior of the blending drum through the porous metal filter elements will, in effect, fluidize the powder during a blending cycle of rotation which is aided by the mixing pins. Fluidizing of the powder, aided by a rocking motion induced by motor 30, plus pneumatic vibrators 86, FIG. 4, causes the material to flow into a vacuum pickup generally designated 88 as indicated by arrows 90 for transfer or conveyance to a next station. The vacuum pickup or conveyor has air introduced therein from an air source through a dry air in quick disconnect means 92 and blended material as indicated in FIG. 1 is conveyed from the blender, preferably through a quick disconnect plug valve generally indicated at 94, which provides for a quick disconnect and additionally serves to prevent air inlet into the chamber during hookup and disconnect. Excess fluidizing gas is vented through the nozzle on the top of the drum and can be filtered by the same vacuum unit used to load the unit when a vacuum is applied to nozzle 66 and powder is introduced through inlet 64.

Specifically different mechanism for unloading the unit is shown in FIG. 9, wherein material flows through discharge outlet 96 into a discharge hopper 98 in which is mounted a screw conveyor 100, having a variable pitch flight and rotatably driven by hydraulic motor 102 from a power source generally designated 104. A discharge spout 106 is arranged at the exit end of the screw conveyor and the material is again conveyed by air entering through air disconnect means 92 and exiting a plug valve 94 similar to the previous arrangement. In one embodiment, a 4 inch diameter variable pitch screw conveyor is used powered by a low speed, high torque hydraulic motor. The hoses disconnect during the blending cycle and are attached for unloading.

. Rocking and vibration will be greatly reduced and injection of gas and resulting problems of dusting and over-pressure are virtually eliminated.

FIG. is similar in concept to the mechanism of FIG. 9, but further includes a container filling concept. The material handling container 108, provided by a customer, is inserted in a closed dust-tight enclosure generally indicated at 110, manually mounted by manual connector means 112 of any suitable type, and which are detached therefrom and removed during the blending cycle.

Air cylinders 114 are incorporated in enclosure to lift container 108 into compressed engagement with an elastomeric material indicated at 109, provided on the discharge spout to provide a seal during discharge. Nuclear level indicator/controller means generally indicated at 116 are provided which function to opera tively transmit a signal to hydraulic motor 102 of the hydraulic unloading system for control of material flow into the container 108 in a manner similar to the embodiment of FIG. 9.

The basic function and operation of the embodiments of FIGS. 1, 9 and 10 are substantially the same. The specifically different discharge mechanisms are optionally usable. The blender is loaded by pulling a hard vacuum on the chamber and conveying powder into it through proper nozzles. Tubing plug valves as hereinbefore referred to are recommended for sealing against the atmosphere while changing connections.

Manifestly, minor changes can be effected in details without departing from the spirit and scope of the invention as defined in and limited solely by the appended claims.

We claim:

I. A nuclear fuel powder blender comprising:

A. a rotatable closed cylindrical blending chamber consisting of a drum;

B. power blending means operably associated with said beldning chamber;

c. drive means for said chamber operable to selectively rotate and rock said chamber for a blending cycle and facilitating discharge of blended powder fromsaid chamber respectively;

D. blended powder discharge outlet from said chamber; and

E. blended powder unloading means operatively opening into said discharge outlet for conveying blended powder from said blender, including means for injecting air under pressure into the bottom half of said drum to fluidize powder therein, the fluidizing in conjunction with rocking said drum causing material to flow to said discharge outlet.

2. A nuclear fuel powder blender as claimed in claim 1, including an air chamber surrounding the bottom half of said drum, a plurality of air injector pads in said chamber spaced peripherally around said bottom half of said drum, porous metal filter elements interposed between said air pads and the interior of said drum, said unloading means including a vacuum pickup positioned below said discharge outlet and adapted to convey blended powder to a subsequent station.

3. A nuclear fuel powder blender as claimed in claim 2, wherein said drum includes a venting nozzle on the top thereof, excess fluidizing gas being vented through said nozzle, a vacuum loading unit in said drum, said vented fluidizing gas being filtered by said vacuum unit.

4. A nuclear fuel powder blender as claimed in claim 1, said unloading means including a variable pitch screw conveyor positioned below said blended powder discharge outlet, an air injection means operatively associated with the discharge end of said screw conveyor to entrain and convey blended powder discharged therefrom, and a vacuum pickup for conveying the powder to a subsequent station.

5. A nuclear fuel powder blender as claimed in claim 1, said unloading means including a variable pitch screw conveyor to receive and impel powder to a discharge outlet therefrom, a material handling container removably positioned below the discharge outlet from said screw conveyor and nuclear level controller means associated with said container for control of the screw conveyor for determining the amount of powder discharged into said container.

6. A nuclear fuel powder blder as claimed in claim 5, including a dust tight enclosure for confining said container, elastomeric sealing means between said container and the discharge from said screw conveyor, means operable to force the mouth of said container into sealing engagement with said discharge outlet, said dust tight enclosure and said container being removed during the powder blending cycle.

7. A nuclear fuel powder blender as claimed in claim 1, said blending chamber comprising a circular, openfaced drum, a removable cover for said drum, a plurality of mixing pins attached to the interior of said removable cover, some said mixing pins acting as stay bolts for structural integrity in the event of excessive pressure buildup in said drum, and others of said pins acting to prevent collapsing of the removable cover during a vacuum loading cycle.

8. A nuclear fuel powder blender as claimed in claim 7, including means for pulling a hard vacuum on said chamber and means for conveying powder into said chamber through nozzles associated therewith and tubing plug valves associated with the vacuum and powder conveying mechanism for sealing against the atmosphere while changing connections between loading, blending and discharge cycles.

9. A nuclear fuel powder blender as claimed in claim 1, said blending chamber comprising a circular openfaced drum, a removable cover for said drum, a hatch on said cover mounted for pivotal movement to open and closed positions, said hatch when open providing access to the interior of said drum.

10. A nuclear fuel powder blender as claimed in claim 9, said hatch being conical, a captured O-ring seal adapted for tapered fitting with said conical hatch, said hatch consisting in two parts divided along the parting line of a seating groove for said O-ring, said parts constituting a bimetallic hatch construction, and quick opening hatch dogs for said hatch.

Claims

1. A nuclear fuel powder blender comprising: A. a rotatable closed cylindrical blending chamber consisting of a drum; B. power blending means operably associated with said beldning chamber; c. drive means for said chamber operable to selectively rotate and rock said chamber for a blending cycle and facilitating discharge of blended powder from said chamber respectively; D. blended powder discharge outlet from said chamber; and E. blended powder unloading means operatively opening into said discharge outlet for conveying blended powder from said blender, including means for injecting air under pressure into the bottom half of said drum to fluidize powder therein, the fluidizing in conjunction with rocking said drum causing material to flow to said discharge outlet.

7. A nuclear fuel powder blender as claimed in claim 1, said blending chamber comprising a circular, open-faced drum, a removable cover for said drum, a plurality of mixing pins attached to the interior of said removable cover, some said mixing pins acting as stay bolts for structural integrity in the event of excessive pressure buildup in said drum, and others of said pins acting to prevent collapsing of the removable cover during a vacuum loading cycle.

9. A nuclear fuel poWder blender as claimed in claim 1, said blending chamber comprising a circular open-faced drum, a removable cover for said drum, a hatch on said cover mounted for pivotal movement to open and closed positions, said hatch when open providing access to the interior of said drum.