CA1109914A - Electric steam generator - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The electrodes of the steam generator are each formed as a horizontally extending disk to receive descending water jets from a distribution chamber above the electrode as well as with openings to direct water jets downwardly onto a collecting grid. The current flows from the electrodes through the water jets to evaporate part of the water to steam. Movable inter-ceptors are also mounted in the vessel to intercept the water jets for partial loads. The invention results in a reduced overall height of the generator. In a particularly useful embodiment, the water distribution means are movable to adjust the number of water jets which impinge on the electrodes while the collecting means for intercepting the excess water are stationary. Each collecting means is also located out of vertical alignment with the respective electrode. The distribution means are fixed to a rotatable pipe which serves to move the distribution means and through which water can be fed to the distribution means. The latter embodiment results in a still further reduction of the overall height of the generator.

Description

The present invention relates to an electric steam generator of the type havin~ at least one electrode disposed in a vessel, and further including a distribution device for directing water to be evaporated against the electrode in the form of jets.
In known steam generators of this type, the electrodes are arranged vertically about a centrally located distribution device and being operatively connected to a three-phase network.
In use, a current flows through the water jets so that part of the water jets evaporates. The steam formed in this manner is collected in the vessel and i~ then fed to the steam consumers while the unevaporated water returns to a sump loca~ed in the lower part of the vessel and forms further current paths. If the consumption of electric power changes, a larger or smaller number of the water jets emanating from the distribution device is intercepted in these known steam generators so as not to reach the ele~trodes. It is a drawback of ~he known steam generators that because of the vertical arrangement o the elec~rodes and of the distribution device, the steam generator has a relatively large overall height as r due to the curved water~jets, it is necessary to provide intercept area of the -electrodes to be of required size in vertical directionO
It is an object of -the pxesent invention to provide a steam generator of the above mentioned type, whose overall height is smaller than in the known prior art devices, and whose steam generating capacity relative to the volume of the generator is increased.
The present invention solves the above object hy an arrangement wherein the elec~rode is formed as a horizontally extending~dish for receiving a supply of water having openings forming outlets for the received water to f~rm vertical water the jets. The distributi~n means has a chamber to receive water, .
- : :

chamber having an approxima-tely horizontal bottom and h~ving a group of openings above the dish-shaped electrode for directing vertical water jets against the electrodeO Due to the fact that the openings in the distribution means are arranged in a horizontal plane and the electrode is in the form of a horizontal dish, the height of the electrode and thereby, the overall height of the steam generator, can be reduced substantially. This makes it possible to accommodate the steam generator according to the present invention in a basement of a normal story height in dwellings, hospitals, and similar buildings. Due to the dish-shaped form of the horizontal electrode and the horizontal arrangement of the openings in the distribution means, a uniform vertical straight-line path of the water jets emanating from the distribution means is obtained. This makes it possible to increase the steam generating capacity over vertically arranged electrodes.
In general terms, the present invention provides, . -in an electric steam generator, the combination comprising; at least one horizontally extending dish-shaped electrode in said vessel for receivlng and~heating a supply of water and having openings therein forming outlets for the received water to form vertical water jets; a distribution mea.ns located above said at least one electrode, said distribution means having a chamber to receive water, said chamber including a horizontal bottom having a group of openings above each of sald at least one :: -electrode for directing vertical water jets against and into each of said at least one electrodei means mounted for movement between each of said at least one electrode and said distribution :.
means for selectively intercepting the flow of water in said -.--water jets between said distribution means~and each of said at ~:
least one electroda; and means for selectively moving said ~: intercepting means across~said latter water jets to intercept .~ :

' and to divert away from each of sa.id a-t least one electrode a number of said latter water jets proportional -to the distance moved between each of said at least one electrode and said distribution means.
The present invention will be described in greater detail with reference to two embodiments shown in the accompanying drawing, of which one has been made the subject of a divisional application.
In the Drawings:
Figure 1 is a vertical section of a steam generator according ~o the present inVentiQn;
Figure 2 is a section along lines II II of Figure l;
Figure 3 is a vertical section of another steam generator, now subject of the said divisional application;
Figure 4 is a partial section IV-IV of Figure 3;
Figure 5 is a partial section V-V of Figure 3 and Figure 6 is a section VI-VI of Figure 4.
Referring to Fig. 1, the electric steam generator has a cylindrical vessel 1 disposed on a vertical axis which ~;
is provided at the top and ~ottom with a convex cover 3 and

2 respectively. The diameter of the vessel 1 is approximately equal to the height o e the vessel, so that the vessel 1 is of :

-2a~
' :
..
, . ' ~ ' : -: .

compact sh~pe. A pipe elbow 4 is connected to the lower cover 2 and is connected via a flange joint to an intake stub 5 of a circulatlng pump 7, which is driven by an eIectric motor 6. An output stub 8 of the circulating pump 7 is flanged to a central pipe 10 which passes through the lower cover 2 and extends close to the upper cover 3. The lower end of the pipe 10 is cylindrical and changes toward the top to a triangular cross-section with rounded corners tsee Fig. 2). ~ pipe line 50 is connected to the lower cover 2 through which feed water is supplied by means of a feed pump ~not shown~ and forms a sump in the lower par of vessel 1.
A plane intermediate plate 12 is provided below the mouth of the central pipe 10 in the vicinity of the upper cover

3 or at the same height as this mouth. This intermediate plate 12 is part of a distribution means for the water to be evaporated which water collects on the intermediate plate 12 as a layer of a certain height. At approximately half height o the vessel 1 three dish-shaped electrodes 20 are provided in a horizontal plane, uniformly distributed over the circumference. Each electrode 20 consists of an approximately horizontal bottom 21 and a frame 22 welded thereto, which extends upward and has a segment-shaped top elevation (see Fig. 2). The bo~tom 21 is equipped with sixty-six noæzles 55, the exit openings of which ,!
are arranged at the in~ersection points o~ two amilies of involutes 26 which are mirror-symmetrical to a radial plane including the axis o the ~essel 1~ Several mutually parallel grid bars 25 are fastened above the nozzles 55 in the frame 22, which form a grid and are omitted in Fig. 2 ~o the left o~ ~he ~ break llne b for the sake of clarity.
A collecting grid 15 is prov1ded below each electrode -20 which conaists of steel strlps 16 arranged on edge sid~ by-side and rests via four leqs 14 on the lower cover 2. Each ~ ~ -3-electrode 20 is supported via two ceramic insulators 18 on the collecting grid 15 located underneath. For this purpose, the grid 15 has two overhanging pla~es 17. The insulators 18 lns~late the respective electrode 20 electrically against the collecting grid 15. Current is supplied to the three elec~rodes 20 via a bar 41 each of which is connected at one end to the bottom 21 of an electrode 2~ via a connecting strip 43 and is brought out at the other end through a radially disposed stub 42 of the vessel 1. ~he bars 41 are enclosed by insulators 40. The three phases of a ~hree-phase network are connected to the outer ends of the bars 41 in a manner not shown in detail.
A group of several nozzles 13 is associated with each electrode 20 and are disposed in the intermediate plate 12 to define openings through which vertical water jets are directed against the associated electrode 20. The arrangement of the noz~les 13 corresponds to that of the no~zles 55 in the electrode 20. A pipe line Sl is connected to the vessel 1 closely below the intermediate bottom 12 and conducts the saturated steam generated in thevessel 1tO the consumers (not shown).
:: 20 ~ Furthermore, the intermediate bottom 12 is:provided on its lower side with a pipe section 28 which is concentric with the central pipe 10 and has a flange 29 at a lower end. The flange 29 has an annular slot of circular cross-section on the upper side in which balls 30 roll and a ring 31 of angular cross-section extends over ~he balls 30 so that an axial bearing is formed. Three collecting trays 35 are distributed circumferentially over the ring 31 and are welded to the ring 31. Each tray 35 is associated with one of the three groups of nozzles 13 and can be swung into the area of the water jets coming from the nozzles 13. ~ach of ~he collecting t.rays 35 is provided with a spout 36 ~Fig. 2) which is pointed toward the wall of the vessel 1 and can move, together witt the collecting

-4-tray 35, over the opening of a collecting pocket 38. The collecting pockets 38 are each formed by a metal sheet 56 which is welded to the inside of the vessel and extends downward to shortly above the water sump. If the collecting trays 35 are swung into the area undernea~h the nozzle 13, part o~ the water jets is thereore intercepted by means of the collecting trays 35 and the water collected is conducted into the collecting pockets 38, so that this intercepted water does not come into contact with the electrodes 20 and therefore does not carry current.
The operation of the steam generator is as follows:

By means of the circulatiny pump 7, water is drawn from the sump and pumped via the cen~ral pipe 10 onto the intermedlate bottom 12, where a water layer is formed, the height of which depends on the amount of water pumped by the circulating pump 7 and on the sum total of the exit cross sections of all nozzles 13. A pipe 52 is provided for pressure equalization between the space above and the space below the intermediate plate 12. This pipe 52 also serves as an overflow. The water collec~ing on the intermediate bottom 12 is distributed over the nozzle 13 and falls in a . .
~ 20 multiplicity o ve~tical jets onto the grid 25 of the dish-shaped .
electrodes 20. The water collec~s in these dishes forming a level.i~ Then, the water 10ws via the no~zles 55 onto the collecting grid 15 underneath and from there to the sump. The current fed in vla the bars 41 flows from the dish-shaped electrodes 20 on;the one hand against the falling water, to the nozzles 13 and on the other hand, in the same direction as the falling water; to the collecting grid 15. The nozzles 13 as ; well as the connecting grids 15 are electrically connected to the vessel 1 and are at zero potential. When the current passe~
throu~h the w~ter jets, steam i generated. The steam is then collected belQw the intenmediate plate 12 and leaves the vessel via ~he line 51.
' .

At full load of the s-team generator, the three collec-ting trays 35 are outside the area of the water jets issuing from the nozzles 13. For a smaller load, the ring 31 with the three collecting trays 35 is moved counter-clockwise in Fig.
by a suitable means ~not shown).so ~hat the collecting trays intercept a larger or smaller part of the water issuing from the nozzles 13. The collected water flows via the spouts 36 into the collecting poc]cets 38 and returns to the water sump.
By the specific arrangement o the nozzles 13 and 55 at the points of interception of two equidistan~ families of involu~es, the number of water jets covered.. by the collecting trays 35 :~
is varied approximately linearly as a function of the angle of rotation. ..
. It may be advantageous to pjro~ide partitions abou~
the individual nozzles 55 at the bottom of t~e dish-shaped electrodes 20 in such a manner that the water leaves the dish in appxoximately the same axis as the watex enters. It is also conceivable to arrange partitions in the dishes in such a manner th t the w~ter is not distri.buted over a larger area . .
or a larger number o~ jets leaving the electrodes than Gorresponds approximately to the number of ~he jets flowing towards the electrode. Finally, the heic~ht o~ the partitions can be arranged in steps. In this manner, at low load, the ; water which is fed-in in only a few jets can be prevented from discharging rom~ too ~large a number of jets.
Instead of equipping the bottoms 21 and the-inter-mediate plate 12 with nozæl~ 55 and 13, respectively, it is . also possible to work nozzle-shaped discharye openings into the bottom 2~1 or .the:plate 12 itself.
.: .
3~ In the: ste~am generator shown~in ~igures 1 and 2, means are provided whereby~- for~a partial load of the steam generator - the water flowin~ toward the electrode is fed only . -5-. ,. ..... . . ~
. - . - . .. . . .. .

to a part of the openings in the electrode. This means consis~s of a movable in~ercepting device which can be moved into the space between the distribution device and the electrode located underneath in order to prevent more or fewer water jets from striking the electrode. However, such a steam generator still has a relatively large overall height because -the distance between the upper side of the electrode and the underside Qf the intercepting device inserted below the distribution device must not be less than a certain value as otherwise there is danger ~ of the current arcing over.
In the embodiment o Figures 3 to 6, the distribu~ion means is arranged to be movable in a hori~ontal direction from its position above the electrode in a direction away from the electrode. The collecting means is mounted in stationary manner in the vessel between the water distribution means and the electrode vertically out of alignment with the electrode, to intercept the watex jets which are not to strike the electrode. As the water distxibution means i5 movable and the collec~ing means is stationary, the distribution means can be arranged closer to the el ctrode, while the collecting means remains outside of the curren~-carrying water jets. Thus, the overall height of the steam generator can be further reduced.
Referring to Fig. 3, ~he steam generator comprises a cylindrical vessel 1 which is disposed on a vertical axis and is provided at its bottom cover 2 to communicate with a suction stub 5 of a circulating pump 7. ~n output stu~ 8 of the pump 7 is connected to a flanged pipe StU~ 10 which is centrally located of the vessel 1 and protrudes upwardly throu~h the vessel bottom cover 2. The pipe stub 10 terminates at a - 30 flan~e 65 somewhat belo~ the le~el of the water sump formed on ~he hottom 2. A bearing;ring 66~of angular cross-section is a~ranged on the flange 65 to surround ~he flanye 65 on the outside ~, ~ 7 .. :
~: . . ~ , . . .
. ~ . ., -with a downward directed rim. A vertical pipe 67 is mounted on the bearing ring 66 to rotate about the axis of the ~essel. This pipe 67 is formed at the lower end with an inward projecting flange 68 which rests on the bearing ring 66. The section of the pipe 67 located below the flange 68 encloses the outer circumference of the bearing ring 66. ~hus, the bearing portion is bridged by the water of the sump acting as an electric conductor. Therefore, there are only negligibly small voltage differences between the bearing surfaces; so that corrosion due to voltage differences is avoided~
The upper end o~ the rotatable pipe 67 terminates in a hexagonal housing 69 which has a rectangular opening 70 in each of three walls. The three openings 70 are thus arranged ; at an angle of 120 to each other. A distribution box 72 which is open at the top and is bolted to the respective wall of the housing 69 via gaskets (not shown~ is connected to each opening 70 to form a chamber to receive water. ~he distribution boxes 72 have the shape of a truncated sector as seen in a top view (Fig. 4). The horizontal bottom of each distribution box 72 is~provided an opening in the shape of a ring sector 73 which is covered from~below by a nozzle pla~e 75 which is fastened to the bottom of the distribution box 72 by means of screws 74.
The nozæle plate 75 has a group of nozzle openings 76 which are arranged in rows in such a manner that the rows are slightly askew to the axis of rotation of the pipe 67. Referring to Figs. 4 and 6, each distribution box 72 has a slightly inclined sheet of metal plate 79 near one boundary wall 72' ' which forms a slot 78 for the chamber. ~s shown, the slot 7 ~ widens towards the top. The plate 79 func~ions as a partition ~ to sepaxate the slot 78 from tbe~remainder of the chamber in the box 72 such that ~he slot 7~ can function as an over~low opening~

- ' :
. ;;.::

. .

In order to drive the pipe 67, a rotatable drive sh~ft 80 is bolted to a cover 69' of the hexagonal housing 69 via a flange and extends through the upper end, i.e. cover 3, of the vessel 1. In addition, a stuffing g1.and 81 i5 mountéd in the.cover 3 to seal the drive sha~t 80 in the cover 3. Iihe drive shaft 80 is in connection with drive means (not sho~n) via which a rotar~ motion o about 45 can be imparted to the rotatable pipe 67 including the three distribution boxes 72, and more specifically, clockwise from the position shown in Fig. 4 and back again. The collection device formed by the collecting dishes 95 is thus disposed within the vessel 1 in a stationary fashion~
As bes~ seen from Fig. 4, three horizontally extending dish-shaped electrodes 88 are arranged underneath the full-load position of the distrihution boxes 72 spaced by 120 over the circumference of the vessel 1~ Each of these eIectrodes 88 is supported by a conduc~or rod 87 which projects into the vessel space radially and is mounted in a stub 85 of the vessel. The : conductor rods 87 serve to supply current and are each surrounded by an insulator~86. Each electrode 88 consists of a horizontal bot~om 89 and an adjoining upward-extending frame 91. The bottom 89 is provided with no~zle outlets 90, which are arranged, corresponding to the nozzle openings 76 of the distrihution boxes :72, in xows which are slightly askew to the axis of the rotatable pipe 67. Vertical partitions ~4 are pxovided between each two adjacent rows of nozzle outlets 90 and extend from the bottom to about 2/3 o~ the height of the frame 91. Collecting .:
: ~ rods g2 are:fastened to the frame 91 above partitions ~4 and run :~
crosswise to the partitions 94 and ex~end in the vertical direction. A collecting ~rid 35 is~provided below each electrode .
88 to collect the:water jets from ~hè electrode 88. Each collecting grid 15:is fastened to ~wo brackets 15' which are : ' _g_ :

welded to the inside of the vessel l and protrude horizontally into the vessel space ~ig. 5~, Referring -to Figs. 3 and 4, a collecting means is moun~ed in stationary manner within the vessel 1 in a horizontal plane between each water distribution box 72 and an associated electrode 88. Each collecting means includes a collecting dish 95 which is secured, as by welding, to a vertical run-off pipe 96. The run of~ pips 95 are fastened by means of U-bolts 97 to U-shaped strip steel brackets 98, which are welded to the wall of the vessel 1. As seen in Fig. 6, the upper left boundary edge 99 of each collecting dish 95 runs approximately radially to the pipe 67 and extends, in the position of the distribution box 72 shown in Fig. 4, underneath this box 72 between the slot 78 and the row of the row o nozzle openings 76 adjacent to this slot 78.
In the operation of the steam generator, water is taken from the sump of the vessel 1 by mea.s of the circulating . pump 7 and pumped ~ia the cen~ral pipe 10 and the ro-tatable ~.
pipe 67 into the:three distribution boxes 72~ The three dis-20 tribution boxes 72 thus ~orm a water chamber in wh~ch the water to be evaporated collects as a layer of a certain height~ From the distribution boxes 72, the water passes via the no~zle openings 76 to the associated electrode 88 in the form of water jets while any excess pumped by the circulating pump 7 flows . ~.
over the upper edge of the~plate:79 into the ovexflow slot 78 :;
and thence into the associated collecting dish 95. For full . ~ p load, the distribution boxe;s 72 are in the positian shown in Fig. 4, i.e. vertically over the electrodes 88, so that a]l the ~:
water jets issuing from the:nozzle openings 76 strike the electrodes 88. The~;excess~water flowing out from the slots 78 - returns via the collectin~dishes 95 and the run of pipes 96 .

to the sump. The water o-E the water jeks coming fxom the boxes :-.. .

72 collects row by row between the partitions 94 of the dish shaped electrodes 88 and is distributed anew and flows via the outlets 90 to the collecting grid 15, again in the form of jets.
The three-phase current fed~in via the three conductor rods 87 flows from the dish-shaped electrodes 88 on the one hand toward the noz~le plates 75, against the falling water, and on the other hand, in the direction of the falling water, to the collecting grids 15. The nozzle plates 75 as well as the collecting grids 15 are electrically connected to the vessel 1 and are at zero potential. During the passage of the current, steam is generated which collects under the top~cover 3 and is conducted via a line 51 to consumers ~not shown). The amount of steam leaving the vessel 1 is replaced by feed water, which is ~ed to the vessel 1, via a line 50 connected to the bottom cover 2 by means .
: of a feed water pump, not shown.
If the load is reaucedr the p~pe 67 is rota~ed via the ~: dr-ive shaft 80 so that the distribution boxes 72 are gradually moved away from the associated electrode 88 in the hori~ontal direction clockwise as viewed in Fig. 4. Thus, one jet after 2Q the other from each box 72 no longer s~rikes the associated electrode 88 and is received by the associated collecting dish 95 from where the water is returned to the sump via the run-off pipe g6. .Accordingly, the steam generation is reduced while the electrlc voltage remains constant.
: A.man hole stub 100 is provided in the cylindrical . wall of the vessel 1 through which all components of the steam g nerator -can be brought into the vessel .-1 and assembled.
The steam generator according to t~e-invention may also be equipped with oniy one electrode instead of with three electrodes.
The invention is not:limited to vessels with a vertiral axis~ It is also possible to use cylindrical vessels .. .. : .

with a horizontal axis, in which case, the dish-shaped electrodes are arranged staggered in the direction of the horizontal axis.
Accordingly, also the distrib~ltion boxes are then arranged to be axially movable.

2n :

. ~:
'~ ' :
','' '.

Claims (8)

The embodiments of the invention in which an exclusive property or privilege is claimed axe defined as follows:

1. In an electric steam generator, the combination comprising a vessel;
at least one horizontally extending dish-shaped electrode in said vessel for receiving and heating a supply of water and having openings therein forming outlets for the received water to form vertical water jets;
a distribution means located above said at least one electrode, said distribution means having a chamber to receive water, said chamber including a horizontal bottom having a group of openings above each of said at least one electrode for direct-ing vertical water jets against and into each of said at least one electrode;
means mounted for movement between each of said at least one electrode and said distribution means for selectively inter-cepting the flow of water in said water jets between said dis-tribution means and each of said at least one electrode; and means for selectively moving said intercepting means acorss said latter water jets to intercept and to divert away from each of said at least one electrode a number of said latter water jets proportional to the distance moved between each of said at least one electrode and said distribution means.

2. In an electric steam generator as set forth in claim 1 which further comprises a collecting grid below and spaced from each of said at least one electrode to collect the water jets from each of said at least one electrode.

3. In an electric steam generator as set forth in claim 1 wherein said intercepting means permits selective feeding of the water jets from said distribution means to a selective number less than all of said outlets of each of said at least one electrode at partial load of the generator, the number of said water jets being in a ration relative to the total number of the openings of a group in said chamber bottom equal to the ratio of said selective number of outlets of each of said at least one electrode to the total number of said outlets of each of said at least one electrode.

4. In an electric steam generator as set forth in claim 1 wherein said intercepting means includes a collecting tray between said chamber and each of said at least one electrode movably mounted about a vertical axis for selective movement into said water jets therebetween.

5. In an electric steam generator as set forth in claim 4 which further comprises a pipe coaxially of said vertical axis for feeding a flow of water to be evaporated to said chamber, each of said collecting trays being mounted on said pipe.

6. In an electric steam generator as set forth in claim 1 wherein at least one of said at least one electrode and said chamber having a plurality of nozzles therein forming said respective openings.

7. In an electric steam generator for generating steam from water, the combination comprising a vessel;
a plurality of electrodes in said vessel, each electrode being of horizontally extending dish-shaped for receiving a supply of water and having openings therein to discharge a plur-ality of downwardly directed water jets;
a plurality of water distribution means in said vessel, each means being located above a respective electrode and having a chamber with a bottom to receive water and a group of openings in said bottom above each respective electrode to discharge a plurality of downwardly directed water jets into said electrode;
means mounted for movement between each of said dis-tribution means and each of said electrodes for selectively intercepting the flow of water in said jets between each said distribution means and respective electrode to divert the inter-cepted flow away from said respective electrode;
means for selectively moving said intercepting means;
a plurality of collecting grids, each grid being dis-posed beneath a respective electrode to receive the water jets issuing therefrom; and means for supplying an electric current to each said electrode to cause evaporation of the water in said water jets issuing from each said chamber and each said electrode.

8. In an electric steam generator as set forth in claim 7 which further comprises means for recirculating water from said collecting grids to said distribution means.