US2668225A - Vaporizable liquid electrode boiler - Google Patents

Description

Feb. 2, 1954 s. LIVINGSTONE VAPORIZABLE LIQUID ELECTRODE BOILER Filed March 20, 1951 Patented Feb. 2, 1954 VAPORIZABLE LIQUID ELECTRODE BOILER Stanley Livingstone, Chattanooga, Tenn., as-

signor to Livingstone Engineering Company, Worcester, Mass., a corporation of Massachusetts Application March 20, 1951, Serial No. 216,525 8 Claims. (Cl. 219-40) This invention relates to electric boilers and more particularly to a boiler of the type which contains one or more electrodes which contact the liquid from which vapor is generated by electric current passing through the liquid.

In commercial forms of such boilers, water is used as the liquid and saturated steam generated by the electric current from the water is used as a source of heat for a load such as a mold or other heat exchanger. Boilers of this type are shown and described in Vickery Patent No. 2,447,294. Another type utilizes a pressure switch to control the operation of the boiler by regulating the electric power input to the electrodes. The switch is pre-set for the desired pressure and when that boiler pressure is reached the switch shuts ofi the power. Pressure switches usually include an adjustable pressure differential device so that when the boiler pressure drops to a pre-set level, the switch turns on the power. Still another type of electrode boiler employs a thermostatic switch control. Since the temperature of the steam or vapor is a function of the pressure, a thermostatic switch with an adjustable on and ofi differential can be used in the same manner as a pressure switch. Where boilers which will develop high temperatures are desired, the design of the boilers becomes expensive because, as temperature demands go up, increased steam pressure must be developed in order to attain the desired temperature. For example, at 40 pounds per square inch gauge pressure saturated steam has a temperature of 286 F. In order to develop steam temperature of 550 F., the pressure must go up above 1,000 pounds per square inch with the result that the boiler, piping, couplings, joints and the pressure seals must be capable of withstanding these exceedingly high pressures.

Nevertheless, particularly in molding, it is desirable to have efiicient units which can develop temperatures in the range of 400-550 F.

According to this invention, an electrode boiler is provided which can developsuch high temperatures of the order of 550 F. without exceeding pressure capacities that would produce, in the case of a steam boiler, temperatures not exceeding about 365 F. Furthermore, an electrode boiler is provided which develops temperatures in the neighborhood of 410 F. without exceeding pressures of five to ten pounds per square inch. This is an extremely important characteristic of this electrode boiler because it permits heating ordinary jacketed kettles, sterilizers, autoclaves and other forms of heat exchangers to temperatures far above those attainable with steam because of the limited pressure capacity of such heat exchangers.

Boilers of this invention may be used in a closed or open system. In the closed system, the boiler is provided with an external fluid circuit leading from its upper or vapor portion to its lower or liquid portion and having interposed in the fluid circuit a mold or other heat exchanger constituting the load and wherein vapor produced in the generating chamber passes through the circuit to the load where it condenses and returns as condensate into the lower portion of the boiler.

When boilers of this invention are used in an open system, the condensate leaving the mold, jacketed kettle or other form of heat exchanger load, is piped to a trap of the ordinary bucket or float type and discharged through an after-cooler into a receiver. From the receiver, the liquid is pumped into the boiler. The after-cooler is a heat exchanger, either air or water cooled. Its purpose is to dissipate heat and lower the temperature of the liquid to avoid loss through evaporation or flashing. The primary purpose of condensate return systems used with steam boilers is to conserve heat but in boilers of this invention, the primary objective is to conserve and recover the liquid.

Boilers of this invention should have thermostatic traps or equivalent devices for continuously venting air or gases that may be in the boiler at starting or generated during operation. One such trap can be mounted on the piping connected to the top of the regulating or surge tank of boilers of the type described in Vickery Patent No. 2,447,294. Pressure or thermostatic switch controller boilers can have the venting device mounted at the vapor outlet from the boiler to the load. In a closed system, another such trap should be located on the condensate return line from the heat exchanger load and close to the heat exchanger.

The invention is predicated upon the use of a novel liquid vapor system in the boiler, which system I have discovered to have all the requirements for such use. It is of such nature that it does not detrimentally break down chemically at temperatures of 400-550 F.; it is conductive and vaporizes in the same manner as water but at a higher temperature and condenses as it gives up its latent heat, It has no adverse eifect upon the materials of which ordinary boilers, piping and heat exchangers are made and has the admirable characteristic of having vapor temperatures of from 400-550 F. at pressures not exceeding about pounds per square inch. In

solve in ethylene glycol, apreferred percentage, being in the order of 5 to 12%.; by weightjaddedq to the ethylene glycol when ,hot, Anywher -salt.

soluble in the glycol to a greater or lesser degree, may, however, be substituted for, the so; dium carbonate, for example; sodium chloride or trisodium phosphate, and otheralkali metal carbonates, bicarbonates, phosphates and halides, in amount sufficientto render; the com: position conductive.

In Fig. 1 of. the drawing,- I, have diagrammatically shown a. closed boiler system of the invention with a self-regulating pressurevalve; and

In Fig. 2, Ihave illustrated thecomparative vapor heat curves of ethylene glycol and saturated steam at increasing-pressures,

Fig. 1 shows a generating tank, 12, having anoutlet l4 runningto a heatxchanger Is as, for egrampletheplatens of amold pressandconnected to a return condensate line H. Electrodes are, disposed within the generating tank I2 andsupplied withsuitable electrical connectionsnot shown, Thermostatictraps 22 and 23 are; provided, as previously described.

The generator; also includes a pressure-regulatingsystern which includesa surge tank connested in a.suitable line extending fro nthe top of the, generating-tankiZ; into the return-cone sa e ne; 5. Th s tt r rc i is o e a l i mitten, a; a e-' safet a ve 36, a pressureregulating valve 38 and a pet cook 40. The pressure regulating valveis. adjustalole-; and acts to -close the regulating, circuit when the pressure in the generating chamber [2 uil sup toams ete m n d pres e t u -cau ing any. conduetivejiquid in the tank 1 12 to back up into thesurgetankjfl and reduce the current nt l-fin WP: h e er t n ank ro sbe w h r d t min d;pre u whe u n t su t n l a ve 58:0nfi st rermit liquid from the surge tank 30',t o ,re-enter at the-bottom ofthe tank. l2. The operationot such a regulatingcircuit is well known., How..- ever, in the instances of its commercial use-and; description, the conductive liquid is waterwiththe resultthat the temperatures attained in the. heat exchanger 16 cannot exceed; the temperature of saturated steam at the pressurefo-r which; the regulating'valve 38 is set.

In accordance with my invention, thetank. l2 isfilled to the levelfill with a glycol containing; an electrolyte which acts in the samemanner as steam to the; extent that it vaporizes as a result of passage of electric current therethrough between the electrodesjll, However, if the pressure regulator hasthe-sarne setting ;as,;in the ase h e t n ato he, e pe at develpped-in the: heat exchanger ;with';the= -use -of my conductive liquid, will be very much greater and supply heat, in the case of ethylene glycol, at substantially the temperatures indicated in Fig. 2 for any given setting of the pressure regulator valve 38.

It will be understood that the form of system and-regulating controlshown in the drawings is merely an example of one application of the invention and that, as previously described, the invention is equally applicable to closed systems having different forms of regulating controls or towopensystems. However, since the invention is concerned notwith the particular type of systerns, but with the nature of the vaporizable liquid used, onlya typical system has been shown in the drawings.

1, claim:

1. An electric boiler having a tank adapted to contain liquid to be boiled, electrodes in said tank, a liquid in said tank contacting said electrodes,, said liquid comprising a mixture of a glycol and an electrolyte, said glycol being adapted to be vaporized by the passage of electric current through said liquid between said electrodes, andmeans for regulating the current input. to said, electrodes to boil said liquid and createv vapor in said system at a pressure corresponding to a temperature at least as great as the boiling point of said glycol mixture and for reducing said current input when said pressure has reached a predetermined maximum.

2. Anelectric boiler as claimed in claim wherein the glycol is ethylene glycol.

3. Anelectric boiler as claimed in wherein the glycol is-diethylene glycol.

4'. An electric boiler as claimed in wherein the glycol is triethylenev glycol.

5.. An electric boiler as claimed in wherein the glycol is propylene glycol.

6, An electric boiler as claimed in claim whereinthe glycolis dipropylene glycol.

7. An electric boiler as claimed in claim 1, wherein the glycol is ethylene glycol and the electrolyteis soda ashin an-amount of about 5%-12.% by weight of the liquid.

8., An electrode boiler having a liquid-vapor system inwhich a liquid in contact with the electrodes, of said boiler comprises a vaporizable glycol containing a-non-vaporizable electrolyte, and the. vapor comprises saidglycol free of said electrolyte.

claim claim claim STANLEY LIVINGSTONE.

References Cited in the. file of this patent UNITED STATES PATENTS Number Name Date 1,546,061 Drefahl July 14, 1925 1,672,899 Miller June 12, 1928 1,709,437 Bush Apr. 16, 1929 1,34-5-,852- Slisz Feb. 16, 1932 1,868,710 McCullough July 26, 1932 1,919,204" Decker .July' 25, 1933. 1,941,855- Eggleston Jan. 2, 1934' 2,162,397 Gray June 13, 1939 2,196,057- Clark Apr. 2, 1940 2,253,506 Clark Aug. 26, 1941 2,375,892 Bouyoucos May 15, 1945' 2x14729 1 Vickery Aug. 17, 1948 2510235 Kogel June 6, 1950 2,593,363- Glendinning-et a1. Feb. 27, 1951

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