US2821614A - Electrical steam generator and method of steam generation - Google Patents

Description

Jan. 28,1958 J. JANSONS 2,821,614

ELECTRICAL STEAM GENERATOR Ania METHOD 0; sum GENERATION Filed July 22, 1955. I v 2 Sheds-Sheet 1 L lfi T I9m E f T a INIVENT'OR 22 l8 Jfl/ZLJ Lia/740724 WORNEYS ZI SIXeetS-Sheet 2 W TTORNEY:

J. JANSONS ELECTRICAL STEAM GENERATOR AND METHOD DE S'iEAM GENERATION Jan. 28, 1958 Filed July 22,.155

United States Patent ELECTRICAL STEAM GENERATOR AND METHOD OF STEAM GENERATION Janis Jansons, New York, N. Y., assignor, by mesne assignments, to Carbon Heater Corporation, New York, N. Y., a corporation of New York Application July 22, 1955, Serial No. 523,808

Claims. (Cl. 219-40) This invention relates generally to apparatus and method for heating of liquids or fluids and more particularly to improvements in electrical water heaters that are intended to generate steam especially to provide the steam jackets of heating vessels or steam tables rapidly with an adequate supply of steam, and to improvements in a method of providing steam for such purposes.

Electrical water heaters are known wherein heating is effected by the conduction of electrical currents through the Water, the water acting as the resistance. Heaters of this character usually make use of spaced carbon electrodes between which the water circulates. Waters at various localities by reason of their different mineral content possess different electrical resistance or conductivity characteristics. Waters are frequently classified according to degree of hardness, namely, in accord with the extent of mineral content. Usually the higher the mineral content the harder the water. Soft water has the least mineral content. -In consequence in the past for a given voltage supply, diflerent waters which were to be heated to the boiling point to supply steam have been found to require different mechanical adjustments in the spacing or effective area between the electrodes.

The problem is of particular importance when the heaters are utilized for steam generation. The adjustment of electrodes heretofore required has been laborious. Moreover, in most cases complex arrangements have been required for providing adjustment in spacing and surface area of contact between the water and the electrodes. These existing arrangements have increased the expense of the heaters extant unnecessarily and in addition have required use of numerous additional parts all subject to mechanical failure.

Objects and features of the present invention are the provision of an improved apparatus for electrical heating of a fluid, such as water for steam generating pur poses which is self-compensating for waters of different resistivity, conductivity, mineral content or degrees of hardness without requiring any mechanical adjustment whatsoever or the electrodes used to produce the steam. In other words, principal objects and features of the invention are the provision of a steam generator of the character in question which may be used universally and irrespective of the local water conditions without requiring any mechanical adjustments or structural changes in the electrodes of the apparatus at each different locale for effective operation at rated capacity.

Further objects and features of the invention are the provision of relatively inexpensive and simple structure for practicing the invention.

Wherein the invention is primarily at present utilized as herein described for steam generation purposes, its utility in connection with heating of other liquids or fluids with varying conductivities or resistivi'ties is apparent.

Further objects and features of the invention will become apparent from the following specification and the accompanying drawings wherein:

Figure 1 is a vertical section of an electrical steam generating apparatus made in accord with the present invention;

Fig. 2 is a transverse section taken along the plane of line 22 of Fig. l and viewed in direction of the arrows;

Fig. 3 is a similar transverse section taken along the plane of line 3-3 of Fig. 1 and also viewed in direction of the arrows; and

Fig. 4 is an isometric view with parts broken away of details of the apparatus embodying the invention.

Referring now to the drawing, the electrical steam generating apparatus made in accordance with the present invention generally comprises a heater assembly 10. This assembly includes a water heating and steam generating chamber G defined within an open-ended outer casing 11 made of suitable metal, such as copper, and a tubular inner electrode shell 12 made preferably of graphite or carbon. The opposite ends of the electrode shell 12 and the metallic casing 11 are closed off by the respective insulating end closure members 13 and 13a which are formed, for example, of ceramic or other insulative heat resisting material.

The end closure member 13 has a centrally disposed recess 14 at its inner face and a centrally located inlet opening 15 extending axially through the body thickness of member 13. The outer periphery of the member 13 is provided with a portion 16 of smaller diameter than the inner diameter of the casing 11 and with an annular flanged portion 17 substantially of the same diameter as the inner diameter of casing 11. This end closure member 13 is fitted into the lower end of the casing 11 until annular flange 17 abuts the lower end of the cylindrical electrode shell 12. The closure member 13 is held in this position by a pressing ring 18 of metallic or other desired material.

The pressing ring 18 has a sleeve-like portion 19 which fits into the space defined between the casing 11 and the reduced portion 16 of the end closure member 13. Suitable steam packing 20 provides a seal between the annular flange 17 and the sleeve 19 and also serves to prevent leakage of steam outwardly of the casing 11 past the end closure member 13.

The center opening 15 of the end closure member 13 is fitted with a removable nipple 21 that is secured in place as by the nut 22. The nipple 21 may be connected in conventional ways to a source of water supply for admitting water into the interior of the casing 11 and shell 12. The annular flange 23 on the inner end of nipple 21 rests within a recess 24 provided in the end closure member 13 and steam packing 25 serves to prevent leakage in the usual manner.

The upper end closure member 13a is provided with an annular ring-like recess 26 surrounding a central axially directed boss 27 arranged at its inner face. The boss 27 includes a central opening 28 which extends axially through the body thickness of the closure member 13a. A second opening 29 is provided in the closure member 13a. This opening 29 also extends axially through the body thickness of said member 13a and is located within the area defined by the annular recess 26. An outlet nipple 30 is positioned within the opening 29. Packing 31 between the head 32 of the nipple 30 and body 13:: eliminates leakage in well-known manner.

The member 13a has a portion 16a of smaller diameter than the internal diameter of the casing 11 and a portion 17:: forming an annular peripheral flange of substantially the same diameter as the internal diameter of the casing 11. The end member 1311 is inserted into the upper end of the casing 11 until its flange 17a abuts the upper end of the. carbon shell 12. A ring-like member 18a substantially identical with the ring like member 18 and having a sleeve-like portion 19a serves to retain the upper end closure member 13a in position. Suitable packing 20a between the inner end of the sleeve-like portion 190 and the flange 17a functions identically with the packing 20 to prevent leakage of steam outwardly from the upper end of the casing 11. The ring- like members 18 and 18a after positioning, as herein described, may be held in place by clamps, tie rods or other conventional means (not shown).

'The inner shell 12 constitutes one of the electrodes required. The second required electrode 35, in this instance a core of carbon or graphite, is adapted to be suspended internally of the shell 12 in concentric relationship thereto from the uppermost end closure member 13a. This second electrode 35 has generally overall cylindrical shape. The upper and major portion 36 of the core elecnode 35 has a uniform diameter which is less than the internal diameter of the shell 12. A conical frusturn or tapered portion 38 immediately adjoins the lower end of the cylindrical portion 36. The major base of this frustum portion 38 has the diameter of the cylindrical portion 36. This frustum portion 38 tapers toward a minor base that is substantially smaller than its major base. A second smaller diametered cylindrical portion 39 immediately adjoins the conically-shaped frustum portion 38 and has a diameter substantially equal to that of the minor base of the frustum portion 38. In effect the electrode 35 thus comprises a cylindrical portion 36 and :a second cylindrical portion 39 of smaller diameter joined by an intermediate or connecting portion 38 which is tapered or shaped like a conical frustum.

Longitudinally extending grooves 40 arranged in quadrant positions of the surface of the core electrode 35 extend the full length of the latter and through all of its portions 36, 38 and 39. The inner bases 40a of the grooves 40 are all parallel with the axis of the electrode 35. In consequence, each groove 40 has its greatest depth in the larger cylindrical portion 36 of the electrode and its least depth in the second cylindrical smaller portion 39 while in the conically shaped frustum portion 38, each groove 40 has a varying depth caused by the tapering contour there of the outer surface of the core electrode 35.

An axially extending centrally located bore 41 is provided at the upper end of the larger cylindrical portion 36. This bore 41 serves to receive a metallic core shaft 42. The shaft 42 fits tightly within the electrode bore 41 and has a reduced diametered portion 43 which extends into the boss 27 of the end closure member 13a. A second reduced diametered portion 44 of the core shaft 42 threaded at 45 extends through a metallic pressurizing sleeve 46 located within the central opening 28 of the end closure member 13a. A conventional steam packing 47 lies between the lower end of sleeve 46 and the portion 43 of shaft 42. A nut 48 when tightened on the threaded portion 45 serves to mount core shaft 42 rigidly on the end closure member 13 1 and to compress the packing 47 for sealing purposes.

With this described arrangement the second electrode 35 is eifectively supported from the end closure member 1311 in concentric relationship relative to the tubular or shell electrode 12. Because of the described shape of electrode 35, the regional annular space 49 defined between its portion 36 and shell 12 is of a uniform width which is smaller than the uniform width of a regional annular space 51) defined between its portion 39 and shell 12, while the regional annular space 51 defined between its portion 38 and shell 12 varies in conformity with the slope of the walls of said portion 38. The variation in width of the regional annular spaces 49, 50 and 51 serves, :as will be described, to permit use of the heater without mechanical adjustment in locales whose waters have differing mineral content, resistivity or degrees of hardness.

In a practical embodiment of the apparatus described :the metal jacket 11 had an inside diameter .of approxiproximately 1%", its wider or longer base a diameter of 2%" and its narrower or shorter base a diameter of approximately 1.95". The second cylindrical portion 39 had a length of approximately 1 /2 and a diameter of approximately 1.95". The lowermost end of portion 39 had a short adjoining cylindrical portion 39a about 34" in length and of a diameter of approximately 1.8". Portion 39a was provided to fit into the recess 14 of end closure member 13a without extending the full depth of said recess so as to center the lower end of the electrode 35.

Each longitudinal groove 40 of the center electrode 35 spanned its full length and had a width of approximately and a maximum depth in the largest diametered cylindrical portion 36 of approximately V These dimensions are by way of example only and are intended to provide adequate steam for the steam jacket I of a conventional steam table T.

With such dimensions a unit operating on a 220 volt electric supply line at current of 60 amps. or approximately at 13.2 klws. is capable of producing approximately 1.34 boiler H. P. and supplying approximately 43 pounds of steam per hour.

When steam is being generated from water of medium hardness the level of water in chamber G lies in spaces 50, 51 and 49 to approximately half the height of the electrodes 12 and 35. For softer water the level would be at a higher elevation and for harder water at a lower elevation than the said mid-height position.

The rate of steam supply can range from approximately 40 to 60 pounds per hour with the structure described and adjustments in current, line voltage and liquid level of water during steam generation can be used to control the steam output within the specified range. Steam pressures of from 50 to p. s. i. are usual operating pressures but operation at pressures below or above this range are possible and are contemplated.

In operation of a heater having the structure described water is admitted via inlet 21 at a rate controlled by a conventional throttle valve VT. This valve VT is adjusted either mechanically or automatically in conventional ways to regulate the rate of water flow in accord with the known degree of hardness, resistivity or conductivity characteristics of the water in any particular locale. For example, if the water is very soft its resistivity is high. Since the heating effect of current flow is the product of the square of the current and the resistance, the necessary water level in chamber G to produce a given steam pressure then is higher than that required where the resistivity of the Water is low, e. g., with a harder Water. Simple adjustment of throttle valve VT to control the level of water in the chamber G permits accommodation of the heater to waters of different degrees of hardness or electrical resistivity.

The throttle valve VT can be manually operated or may be provided with a conventional magnetic control C which is connected in the electric circuit supplying current to the electrodes 12 and 35 so that the extent of valve throttling action can becontrolled by the current flowing in the circuit. Thus automatic control of the water level in the chamber G in conformity with the resistivity or hardness of the water may be effected.

The Water entering the chamber G via inlet 21, recess 14 and grooves or slots 40 fills it to the selected level determined by the adjustment of the throttle valve VT and completes the electric circuit between the portions of electrodes 12 and 35 with which the water is in contact. The passage of the current through the water heats it to the boiling point and the rising steam vapor makes its way upwardly through the boiling water, the regional annular spaces 50, 51 and 49 in chamber G and the grooves 40 in the center electrode 35 to the recess 26 in end closure 13a. The steam entering recess 26 fiows outwardly thereof via outlet nipple 30 which may be connected by any appropriate conduit, to, for example, the steam jacket I of a steam table T or to any other heating apparatus requiring steam for heating or other purposes.

The reason the steam generator herein described is effective for universal use without mechanical modification of its electrodes with waters of differing resistivity or conductivity in differing locales is the shape of its electrode 35. The different herein described dimensional characteristics of its three portions 36, 33 and 39 provide three difierent zones or regions 49, and 51 whose spacing relative to the other electrode 12 varies as has been described. The heating effect on the water depends upon the magnitude of the voltage applied between the electrodes, and the spacing and the efiective area of the opposing electrodes in actual contact with the water. The shape of electrode 35 provides a relatively wide range of spacing variation and effective contact area by simple control of the level of water in chamber G. In consequence, under practical operating conditions waters of substantially any degree of softness or hardness may be utilized effectively for generation of steam within the rated capacity of the apparatus. The elimination of any necessity for mechanical structural changes in the unit either by way of introduction of additional electrodes or by way of removal of electrodes or by way of any change of relative positions of electrodes is an outstanding ad vantage of the instant invention. The savings in costs for manufacture, installation and maintenance are substantial.

The apparatus described herein and the method of heating practiced therewith are applicable not only for use with water but with any fluids whose conductivity or resistivity may vary under diiferent circumstances. In such event control of the contact between the liquids or fluids and the electrodes and its confinement to selected regions of the difierently spaced portions of the fixed electrodes chosen in accord with the specific conductivity or resistivity of a particular liquid are all that are required. No mechanical change is needed.

While a specific embodiment of the invention has been described, variations in structural detail within the scope of the claims are possible and are contemplated. There is no intention, therefore, of limitation to the exact details shown and described.

What is claimed is:

1. Apparatus for heating fluid by electrical conduction comprising a heater assembly including a tubular electrode, end closure members mounted on said electrode for sealing both ends thereof and a core electrode extending axially within the tubular electrode and in spaced relationship therewith, said core electrode having portions of differing dimensions to provide variations in spacing between respective portions of said core electrode and said tubular electrode whereby like heating eifect may be produced in fluids of diflerent conductivities by varying the extent of contact of the fluid within the tubular electrode with said portions of said core electrode, and means providing an inlet for water into the space between the electrodes and an outlet for steam generated therefrom.

2. Apparatus for heating water by electric conduction to generate steam comprising a heater assembly including a shell-like electrode, end closure members for said electrode sealed at opposite ends thereof and a core electrode supported from one of said end closures and centrally disposed within the shell-like electrode and in spaced relationship therewith, said core electrode having a plurality of portions of differing dimensions to provide variations in spacing between respective of the said portions of said core electrode and said shell-like electrode whereby like steam generation may be effected with waters of dilferent degrees of hardness by varying the extent of contact of such Waters within the shell-like electrode with said portions of said core electrode, and means providing an inlet for water into the space between the electrodes and an outlet for steam generated therefrom.

3. Apparatus for heating Water by electric conduction to generate steam comprising a heater assembly including a tubular electrode, end closure members for said tubular electrode, a core electrode supported by a first of said end closure members and extending axially of the tubular electrode and in spaced relationship therewith, said core electrode having a plurality of successively arranged portions of different dimensions to provide successively differing variations in spacing between respective of the said portions and said tubular electrode and grooves in said core electrode, said first of said end closure members having an outlet for steam generated in said apparatus and the other of said end closure members having an inlet for water and said grooves providing entrance and exit communications respectively with the inlet for water and the outlet for steam.

4. Apparatus for heating water by electric conduction to generate steam comprising a heater assembly including a tubular cylindrical electrode, end closure members for said electrode, a core electrode extending axially and concentrically of the tubular electrode between said end closure members, said core electrode having a first uniformly diametered cylindrical portion, an adjoining frustum portion and a second uniformly smaller diametered cylindrical portion adjoining the frustum portion, said portions all having smaller diameters than the inner diameter of said cylindrical electrode and thereby providing varied spacing between the tubular electrode and the differing portions of said core electrode, one of said end closure members has a recess provided with a water inlet and the other of said end closure members has a recess provided with steam outlet, and said core electrode having axially extending grooves in communication with both of said recesses, and means to secure said core electrode to said other of said end closure members.

5. Apparatus for heating water by electric conduction to generate steam comprising a heater assembly including a tubular cylindrical electrode, end closure means for sealing off opposite ends of said electrode, water inlet means in one of the end closure means and steam outlet means in the other end closure means, a core electrode concentrically disposed within said tubular electrode and spanning the distance between the end closure means and being in spaced relationship with said tubular electrode throughout its length, said core electrode having a first uniformly diametered portion, a second uniformly smaller diametered portion and a frustum portion joining said two first-named portions and thereby providing variations in spacing between the tubular electrode and the respective portions of said core electrode, and said core electrode having longitudinally extending grooves in its surface spanning its length, said grooves providing entrance passageways to the space between the electrodes for water supplied to said inlet means and outlet passageways from said space to said steam outlet means for steam generated in said space, and means for regulating the level of water in said space in accord with its hardness.

References Cited in the file of this patent UNITED STATES PATENTS 1,597,362 Henriksson Aug. 24, 1926 2,106,019 Roberson Ian. 18, 1938 2,185,786 Eaton Jan. 2, 1940 2,556,656 Lehman June 12, 1951 2,611,852 Eaton Sept. 23, 1952 2,612,592 Paulison et al Sept. 30, 1952 2,623,980 Toensfeldt Dec. 30, 1952

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