US3749549A

US3749549A - Continuous heating apparatus for granular material

Info

Publication number: US3749549A
Application number: US00221963A
Authority: US
Inventors: B Henderson
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-01-31
Filing date: 1972-01-31
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31

Abstract

The apparatus includes a heating chamber having a heat exchanger located therein provided with a series of angularly disposed plates, heated directly by a flame, that gives a cascade effect on sand falling thereover. Thermostats are provided within the heat chamber and at the sand discharge opening for controlling the temperature of the sand. An adjustable sand flow control arrangement directs sand at a constant rate to the heat exchanger.

Description

United States Patent 11 1 Henderson [451 July 31,1973

[ CONTINUOUS HEATING APPARATUS FOR GRANULAR MATERIAL [76] Inventor: Barry C. Henderson, 2760 Westridge Rd., Winston-Salem, NC.

22 Filed: 11111.31, 1972 21 Appl. No.: 221,963

[52] US. Cl. 432/49, 34/171 [51] Int. Cl. F27b 1/00, F26b 17/12 [58] Field of Search 263/29, 30, 31; 34/171; 432/49 [56] References Cited UNITED STATES PATENTS 2,824,384 2/1958 Niemitz 34/171 X 3,140,865 7/1964 Cohen 263/30 685,336 10/1901 Le Roy et al. 263/30 789,807 5/1905 Holl 263/171 X 3,274,702 9/1966 Kleinbcrg 263/30 Primary ExaminerJohn J. Camby Attorney-David Rabin [5 7 ABSTRACT The apparatus includes a heating chamber having a heat exchanger located therein provided with a series of angularly disposed plates, heated directly by a flame, that gives a cascade effect on sand falling thereover. Thermostats are provided within the heat chamber and at the sand discharge opening for controlling the temperature of the sand. An adjustable sand flow control arrangement directs sand at a constant rate to the heat exchanger.

12 Claims, 6 Drawing Figures Patented July 31, 1973 3 Sheets-Sheet 1 FIG.2

FIG.4

Patented July 31, 1973 5 Sheets-Sheet 2 FIG. 5

Patented July 31, 1973 3 Sheets-Sheet i5 CONTROL RELAY HEAT THE RMOSTAT SAND THERMOSTAT INDlCATING LIGHT {MAIN IGNITION TRANS.

FLOW REG. V.

W FOJE MAIN FLOW GAS REG V REG.

PILOT Am? 0341 ZOCLZQ GAS SUPPLY CONTINUOUS HEATING APPARATUS FOR GRANULAR MATERIAL BRIEF SUMMARY AND OBJECTS OF THE INVENTION This invention relates generally to the heating or drying of granular material, and more particularly to a continuous heating apparatus for sand whereby the sand exiting from the apparatus is maintained at a predetermined temperature.

Sand is the primary material utilized in the manufacture of foundry molds and cores. Generally, ingredients are added to the sand to improve its molding and core making qualities. These ingredients affect the strength, surface quality, durability, and processing of the molded sand as well as various metal components cast in the molds.

Treating the sand by a heating process affects the manner by which the sand subsequently responds to the various additives. If the sand is heated properly in a manner which allows moisture to escape and which provides a uniform temperature throughout the processed sand at a preselected and controlled temperature, the resin and catalyst additives mix more thoroughly and set quicker and deeper. Less additives need be added and production rates are increased.

The heating apparatus of the present invention removes moisture from the sand and responds to varying incoming sand temperatures to heat the sand uniformly on a continuous basis.

Briefly, the heating apparatus of the present invention includes a structure which defines a chamber and houses a heat exchanger over which the sand is directed. The heat exchanger generally is in the configuration of an inverted V having a plurality of angularly disposed heat conducting plates which provide a cascading effect for uniformly mixing and controlling the rate of flow of the sand downwardly by gravity. The heat exchanger is of an open type configuration which permits moisture to be driven off. A burner flame is directed upwardly between the legs of the heat exchanger to heat the angularly disposed plates. A sand hopper, having a sand flow control gate located at the base thereof, is positioned above the chamber. Perforations in the flow control gate distributes the sand uniformly to both sides of the heat exchanger. Automatic control of the sand temperature exiting from the heat exchanger is affected by adjustable thermostats sensing temperature in the chamber and sensing the temperature of the exiting sand.

One of the primary objects of the invention is the provision of an apparatus for heating sand uniformly to a preselected temperature on a continuous basis.

Another object of the invention is the provision of a heating apparatus wherein the sand flow rate through the apparatus is adjustable and a constant flow is maintained over the heat conducting plates.

A further object of the invention is the provision of an apparatus for heating sand while being conveyed by gravity in a zigzag fashion at a given flow rate with the sand free falling after each reversal of direction of sand flow.

Still another object of the invention is the provision ofa sand heating apparatus which is simple in construction and reliable in operation.

Other objects and advantages of the invention will become apparent when considered in view of the following detailed description and drawing.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a side elevational view of the sand heating apparatus of the present invention;

FIG. 2 is a cross-sectional view of the sand heating apparatus taken along line 2-2 of FIG. 1 illustrating the heat exchanger located intermediate the upper and lower hoppers;

FIG. 3 is a perspective view of the heat exchanger illustrating the angularly disposed heat conducting plates;

FIG. 4 is an enlarged, fragmentary, side elevational view of one leg portion of the heat exchanger of FIG. 3 and illustrating the angularly disposed plates and the path of travel of the heated sand;

FIG. 5 is an exploded, fragmentary, perspective view of the heating apparatus illustrating the adjustable flow control gate; and

FIG. 6 is a schematic diagram of the various burner and temperature controls.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing and particularly to FIGS. 1 and 2, there is shown an upstanding, generally rectangular structure 10 which encloses a heat exchanger 12 in a chamber 13. The upper end portions of the structure I0 is open and cooperates with angularly disposed walls 14 to define an inlet hopper 16 for the sand. Below the heat exchanger 12, and intermediate the support legs 18 of the housing, are converging walls 20 which define a heated sand discharge opening 22. Heat is provided by a burner unit 24 mounted upon a support 26. The flame from the burner is directed upwardly towards the heat exchanger 12 by means of a flame directer 28 which is substantially centrally disposed at the base of the heat exchanger 12.

The heat exchanger 12 is generally in the form of an inverted V having an apex positioned immediately below the upper sand hopper l6, and diverging

leg portions

30 and 32 which rest upon supports 34 within the structure 10. Each

leg portion

30 or 32, includes spaced

channel members

36 and 38 interconnected with a series of angle members 40 welded together as at 42, see FIGS. 3 and 4. Spaced in parallel relation with one leg 45 of each angle member 40, to define a passage 44, is a plate 46. The plate 46 extends outwardly and upwardly beyond the plane through the other leg 47 of the angle member, as shown by FIG. 4, to direct sand through the passages 44. A cap 48 overlaps the abutting edges of the uppermost angle members 40 at the apex of the heat exchanger 12. The arrangement of the heat conducting angle members 40 and plates 46 and the steep slopes, approximately of the

leg portions

30 and 32 provides a high energy, quick fall sand course with nonoverloading features. Since the sand is deposited at a given flow rate upon the uppermost portion of the heat exchanger 12, the angle members 40 and plates 46 give the sand a cascading effect and thus prevents the sand from backing up and retarding the incoming flow. The sand is required by plates 46 and angles 40 to follow a zigzag course, as shown by FIG. 4, which causes the sand to be mixed uniformly. It is to be noted that the cascade effect heat exchanger 12 has an important flow-energy re-establishing feature whereby the sand free falls after each short slide on the surfaces of angle members 40 and plates 46.

Within the hopper 16 at the base of the converging walls 14 is a sand flow rate control mechanism 50 including a sand gate comprising a perforated slide member 52, see FIG. 5. Below the slide member 52 is a bottom plate 54 having a series of openings 56 which are adapted to be aligned with the openings 58 of the perforated slide member 52. The bottom plate 54, along with edge member 60, serves to support and guide the slide member 52. The rate of flow of the sand from the hopper 16 to the heat exchanger 12 can be accurately controlled to maintain a given flow rate depending upon the positioning of the

openings

56 and 58 relative to each other. The sand gate design allows a very short displacement of the slide member for flow shut-off and start-up. A bracket 62 is secured at each end of the slide member 52 and has openings for threadably re ceiving adjusting screws 64. The positions of the screws 64 relative to the bracket 62 may be secured in adjusted positions by lock nuts 66. The inner ends of the screws 64 abut the exterior surface of the structure to limit inward displacement of the slide 52 and thereby regulate the position of

openings

56 and 58 thereby controlling the sand flow. Therefore, the sand flow rate through the heating apparatus has the capability of being preset to match and integrate with neighboring process equipment. Upon shut-off of sand through the heating apparatus and subsequent restart, the flow rate re-establishes to the pre-set amount.

The structure 10 may include a supporting frame 68 which supports sheet metal plates 70. The inner portions of the plate 70 may be lined with insulation 72. One or more vents 74 is provided in the upper portion of structure 10 to allow moisture in the sand to be driven off.

PK]. 6 is a schematic diagram of a typical electrical and burner control arrangement for controlling the temperature of the sand exiting from the chamber 13 and opening 22. An adjustable thermostat 76 including an element 78 for sensing the temperature within the chamber 13 of the heating apparatus is connected in series with an adjustable thermostat 80 which includes element 82 for sensing the exiting sand temperature. Thus the heating apparatus of this invention responds to the varying incoming sand temperature to maintain the preselected discharge sand temperature constant. When there is not a demand for sand, there is no sand in the chamber 13 or at the discharge opening 22. Thus the sand thermostat 80 calls for heat which allows the internal temperature of the apparatus within chamber 13 to build and hold to the value of that of the upper chamber thermostat 76. The thermostat 76 is not used as a safety high limit as is usual in heating practices but serves as an important sand temperature controlling element. The sand is only in the chamber 13 an extremely short period of time. Controlling the chamber temperature provides a heat input to the incoming sand necessary to maintain a predetermined temperature at discharge exit 22. In combination with the thermostat 80, automatic control of the sand temperature is effected. If only the thermostat 80 were allowed to control, hundreds of pounds of sand would pass through the chamber before the pre-set sand temperature would be reached. Adjusting the upper thermostat permits setting the heating apparatus for specfic conditions, that is, high values for extremely cold sand as in winter conditions, and low values for warm sand as during summer conditions.

Although the heating apparatus is adapted to operate continuously, sand to be heated may flow through the chamber 13 intermittently depending upon the demand. At shut-off of sand flow by the control gate, since quantity flows of 300-1000 pounds per minute are involved, the sand in the chamber at any one time must be minimal to reduce waste and over run. If sand were left in the chamber, hot spots would develop. if the burner was turned off, it could not respond fast enough to heat the incoming cold sand at the quantity rates involved when additional sand is required.

in view of the temperature controls and the adjustable sand flow control, the apparatus heats and controls the sand on a time rate basis. The heating and controlling of the sand is extremely fast thus eliminating sand overrun and start-up delays.

During operation, the flame of burner 24 is directed upwardly by the deflector 28 thereby heating directly the plates 46 and angle members 40. it is to be noted that as the sand fallsfrom the lowermost plates 46, it passes through the flame area and to the discharge opening 22.

I claim:

1. Apparatus for heating granular material comprising means defining a chamber, a heat exchanger located within said chamber, said heat exchanger including means over which the granular material is directed, heating unit means for applying heat directly to said heat exchanger, granular material flow rate control means for adjusting and maintaining a preselected flow rate over the heat exchanger, and means for controlling said heating unit means to heat the sand uniformly and maintain a predetermined, constant temperature of the granular material as it exits from the chamber.

2. Apparatus for heating granular material as recited in claim 1, wherein said heat exchanger includes at least one portion defining a steep slope with respect to the horizontal for defining a high energy, quick fall, granular material course, and the heat exchanger further includes a series of heat conducting angle members and plates for confining the flow of granular material to a zigzag path.

3. Apparatus for heating granular material as recited in claim 2, wherein said plates and said angle members are arranged relative to each other to permit free fall of the granular material intermediate said plates for uniformly mixing the granular material and maintaining a constant flow.

4. Apparatus for heating granular material as recited in claim 2, wherein said heat exchanger is generally in the shape of an inverted V and said heating unit means applies a flame to said angle members and said plates intermediate the legs of the inverted V.

5. Apparatus for heating granular material as recited in claim 4, wherein the granular material passes through the direct flame as it is discharged from the heat exchanger.

6. Apparatus for heating granular material as recited in claim 3, wherein said granular material flow rate control means includes a flow control gate located above said heat exchanger for controlling the flow of granular material onto said heat exchanger, and means for adjustably regulating the opening of said gate.

7. Apparatus for heating granular material as recited in claim 6, said means for controlling the temperature of the granular material as it exits from the chamber including means for sensing the temperature within the chamber and for sensing the temperature of the granular material as it exits from the chamber.

8. Apparatus for heating granular material as recited in claim 7, said sensing means including adjustable thermostats.

9. Apparatus for heating granular material as recited in claim 1, said means for controlling the temperature ofthc granular material as it exits from the chamber including a thermostat for sensing the temperature within the chamber and a thermostat for sensing the temperature of said discharging flow from the chamber.

10. Apparatus for heating granular material as recited in claim 1, said granular material flow rate control means including an adjustable flow control gate comprising a pair of members positioned in superposed relation, each of said members defining a plurality of openings therein, one of said members being slidably displaced relative to the other to regulate the positions of the openings of one member relative to the other to control the flow of granular material therethrough.

11. Apparatus for heating granular material comprising means defining a chamber, a heat exchanger located within said chamber, said heat exchanger including means over which the granular material is directed, heating unit means for applying flame directly to said heat exchanger, granular material flow rate control means for adjusting and maintaining a preselected flow rate over the heat exchanger, and means for regulating said heating unit for controlling the temperature of the granular material as it exits from the chamber.

12. Apparatus for heating granular material as recited in claim 11, wherein said chamber comprises a combustion chamber.

Claims

9. Apparatus for heating granular material as recited in claim 1, said means for controlling the temperature of the granular material as it exits from the chamber including a thermostat for sensing the temperature within the chamber and a thermostat for sensing the temperature of said discharging flow from the chamber.