US3032635A - Heater and utilization system for converting small quantities of fusible solids - Google Patents

Description

May 1, 1962 A. 1.. KRAFT 3,032,635 HEATER AND UTILIZATION SYSTEM FOR CONVERTING SMALL QUANTITIES OF FUSIBLE SOLIDS Filed Oct. 5, 1960 FIG.Z

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INVENTOR AUGUST L. KRAFT ATTORNEY United States Patent Ofiice 3,032,635 Patented. May 1, 1962 3 032 635 HEATER AND UTILIZATlON SYSTEM FOR CON- VERTIN G SMALL QUANTITIES F FUSIBLE SOLIDS August L. Kraft, 120 Bender Ave., Roselle Park, NJ. Filed Oct. 3, 1960, Ser. No. 60,080 4 Claims. (Cl. 219-19) This invention relates to a method and system for handling in molten form materials which when cool are in the form of powdered solids. In the case of materials such as the anhydrides, and solids such as dichlorobenzidrine and dichlorohydrin, difficulties are encountered, due to the tendency of such materials to oxidize or sublime if held in the molten state for any appreciable time.

It is accordingly an object of this invention to provide a system including a fast acting heating agency which automatically will provide a small, but fixed, supply of molten material.

An additional object of the invention is the provision of an eflicient and very fast acting heating unit.

A feature of the invention is a heating unit which may consist of a substantially solid mass of conducting material which is sufficiently porous to be permeable to liquids. A heating unit of this type provides large areas of heating surfaces, both internal and external, Which are in intimate contact with the material during the preliminary melting stage and also during the passage of the molten material through the heater. Suitable solids for this purpose are carbon, fused quartz or silica with controlled conducting impurities. If desired, porous stainless steel or porous bronze may be used.

In accordance with a further feature of the invention, the heating unit may consist of a spirally wound ribbon of conducting material with the turns of the ribbons spaced by a corrugated ribbon of insulating material. In this form of the invention, the interstices created by the corrugated spacer render the heater permeable to liquids.

Heaters constructed in accordance with this invention are capable of operation at very low wattage per unit area. The thickness or depth of the heater is a major factor in obtaining increased efliciency in terms of watts per unit area.

The invention will be better understood from the following detailed description, reference being had to the accompanying drawings.

FIG. 1 discloses apparatus and control circuits for converting fusible solids in powdered form into a liquid state together with an electrical circuit for maintaining a small amount of molten material at a desired level.

FIG. 2 discloses a heating unit in the form of a permeable conductor or semi-conductor.

FIG. 3 illustrates a heating unit in which the heating unit is a disc assembled by rolling into a spiral a ribbon of conducting material, the convolutions of the spiral being spaced from one another by a continuous corrugated strip which may be made of plastic or other insulating material. If desired, the convolutions may be wound so as to form a rectilinear solid without departing from the spirit of my invention.

Referring now to FIG. 1, a container 1 of any desired configuration is provided with a closure cap 2 and an outlet pipe 3 threaded into a boss 4 formed on the bottom of the container. A heating unit 5 provided with suitable connections to electrical conductors 6 and 7 is mounted in the lower portion of the container in any convenient manner. A float switch generally indicated at 8 is mounted below the heating unit with its operating float ball 9 at an elevation so disposed as to maintain the molten mate rial 10 at a desired level. A float operated switch 11 is mounted in pipe 3 and is so disposed as to operate when the level of the molten liquid from pipe 3 drops below a desired predetermined level. A pipe 12 is secured to pipe 3 by means of a threaded cap 13. In operation, the powder to be liquefied is inserted in receptacle 1 and rests on the upper surface of heater 5. Assuming that there is no liquefied material in the container below the heating unit, float switches 8 and 11 will both be closed. As a result, the closure of switch 15 completes an obvious circuit from a source of power 16 to the heating unit through switches 8 and 11 in series.

The heater, alternative forms of which will be more fully described hereinafter, is of a nature to provide intense heat at relatively low voltages. As its entire upper surface is covered with the powder, liquefaction begins over the entire area simultaneously and with minimum delay. The molten material, in response to both gravity and the pressure of the powder in the reservoir, will immediately start to enter the porous openings of the heater. During the passage of the molten material through the heater, it is again in intimate contact with the walls of the interstices so that it is continuously heated throughout its passage and emerges from the bottom of the heater in drops which have attained a high temperature. After the lower pipes have filled and liquid 10 rises to the desired predetermined level, float valve 9 operates to open the circuit of heater 5.

The molten material may then be dispensed as desired into utilization equipment of any desired nature. When the liquid level in pipe 3 drops below a predetermined level, float valve 11 closes. Float valve 9 will have previously closed as soon as the level of liquid 10 starts to drop. As a result, the closure of switch 11 completes the circuit to heater 5 and a new cycle is begun.

In FIG. 2 the heater is shown in the form of a solid block 26 provided with suitable connecting electrodes as indicated at 17. Obviously the heater may be of any desired form, such as circular or elliptical discs or in rectilinear form of any desired proportions. Suitable materials are carbon, fused quartz or silica with controlled conducting impurities. Porous stainless steel and porous bronze of a composition commonly used as filters are satisfactory materials.

The heater shown in FIG. 3 is made by winding into spiral form a conducting strip 18 on which a corrugated strip 19 of insulating material formed of any suitable plastic has been superposed. Electrical connection to the strip may be made at terminals 20 and 21. In this form of the invention the voids created by the successive alternations of the corrugated strip provide the openings through which the liquefied material may pass. It is to be understood that the voids as shown in FIG. 3 are greatly magnified and that in practice they must be small enough to prevent passage of the powdered solid. While the heater has been shown in disc form, it may, if de sired, be Wound into any shape appropriate to the cross section of the reservoir with which it is to be used.

It is evident that the conductor may be formed into a corrugated strip with a flat strip of insulating material as the spacer.

What is claimed is:

1. An electrical heating unit consisting of a substantially solid cake of conductive porous material, electrical terminals connected to separated surfaces of said cake, a source of electrical energy, heat-liquefiable material in powder form, said cake being impervious to said material in powder form but permeable to said material after liquefaction by said heating unit in response to the passage of electrical energy therethrough, the thickness of said cake being sufficient to provide interstitial passages of substantial length so that internal heat is applied to said liquefied material for an extensive period of time while in intimate contact with said passages during transit therethrough, whereby said liquefied material emerges at high temperatures.

2. An electrical heating .unit consisting of a spirally wound strip of flat material, said strip being of substantial Width, the successive convolutions of said strip being spaced from one another by a substantially continuous strip of corrugated material of like width, one of said strips being an electrical conductor and the other strip being an insulator, a source of electrical energy, electrical connections to the conducting strip, heat liquefiable material in powderform, said heating unit being impervious to said material in powder form but permeable to said material after liquefaction by said heating unit in response to the passage of electrical energy therethrough,

the width of said strips being sufiicient to provide inter- .stitial passa'ges of substantial length so that internal heat is applied to said liquefied material for an extensive period of time while in intimate contact with said passages during transit th'erethrough, whereby said liquefied material emerges at high temperatures.

3. The combination of the heating unit of claim '1 with a utilization system, said utilization system in'cluding'a container in which said heater .is mounted, fusible material in the'form'of a powdered solid disposed in said container and supported by said-heating unit, anelectrical circuit, rneanstto energize said heating unit by way of said circuit and to liquefy said powdered material, a reservoir below said heating unit, and automatically operated switches to maintain the liquefied material at a level between desired upper and lower limits.

4. The combination of the heating unit of claim 2 with a utilization system, said utilization system including a container in which said heater is mounted, fusible material in the form of a powdered solid disposed in said container and supported by said heating unit, an electrical circuit, means to energize said heating unit by way of said circuit and to liquefy said powdered material, a reservoir below said heating unit, and automatically operated switches to maintain the liquefied material at a level between desired upper and lower'limits.

References Cited in the file of this patent UNITED STATES PATENTS m n i

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