GB1588334A

GB1588334A - Through water current flow electric steam generator

Info

Publication number: GB1588334A
Application number: GB3134077A
Authority: GB
Original assignee: Sulzer AG; Gebrueder Sulzer AG
Current assignee: Sulzer AG
Priority date: 1976-10-29
Filing date: 1977-07-26
Publication date: 1981-04-23

Description

(54) THROUGH WATER CURRENT FLOW ELECTRIC STEAM GENERATOR (71) We, SULZER BROTHERS LIMITED, a Company organised under the laws of Switzerland, of Winterthur, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an electric steam generator in which water is directed to fall from a water distribution device in streams or jets onto an electrode for the conduction of electricity through the streams of water to heat it to generate steam.

Accordingly, the present invention provides an electric steam generator comprising at least one water distribution device defining a weir to permit water in said device to overflow at least a part of said weir freely for all loads of the steam generator; a variable water supply means for supplying water to said distribution device; and an electrode positioned below said distribution device to receive water overflowing said weir in free fall and conduct electric current through that water.

In use, the water to be evaporated collects at the lowest point of the distribution device and leaves the device if the water level has reached the lowest point of the overflow edge defining the weir. With increasing load, the level in the distribution device rises and the water stream leaving the device changes in dimension continuously and, thereby, the total flow cross-section of the falling water increases continuously.

These and other objects and advantages of the invention will become more apparent from the following detailed description of some exemplary embodiments of the invention taken in conjunction with the accompanying drawings in which: Fig. 1 illustrates a vertical cross-sectional view of an electric steam generator according to the invention; Fig. 2 illustrates a vertical cross-sectional view through a dish-shaped distribution device of Fig. 1; Fig. 3 illustrates a detail of the device in a cross-section according to the line III-III in Fig. 2; Fig. 4 illustrates a perspective view of a modified detail of the device as per Fig. 2; Fig. 5 illustrates a vertical cross-sectional view through another embodiment of the distribution device and the electrode according to the invention; Fig. 6 illustrates a modified detail of the electrode of Fig. 5;; Fig. 7 illustrates a vertical cross-section through a further embodiment of a distribution device having a serrated rim in accordance with the invention; Fig. 8 illustrates a top view of a further embodiment of the distribution device and the electrode in accordance with the invention; and Fig. 9 illustrates a view of the electrode of Fig. 1 partly in cross section.

Referring to Fig. 1, the electric steam generator has a horizontal, cylindrical vessel 2 to which feed water is fed to collect in a sump at the bottom, via a line 3 and from which steam is taken off at the top via a pipe 4. The water is taken from the sump via a connecting pipe stub 6 and is returned to the vessel 2 by means of a circulating pump 7 via a riser 8 which contains a throttle 9, a distribution line 10 running perpendicularly to the plane of the drawing, and three branch lines 12 which branch off from the line 10 and lead to the top of the vessel 2. Each of the branch lines 12, of which only one is visible in Fig. 1, is equipped with a choke plate 13. A horizontal, dish-shaped distribution device 20 is arranged in the vessel 2 underneath the mouth of each branch line 12.

Each distribution device 20 is formed of sheet metal and is constructed as a shallow conical surface which is open toward the top.

The distribution device 20 is fastened at the rim to the vessel 2 via two sheet metal lugs 14, for instance, by welding. An electrode 25 is arranged at about half the height of the vessel 2 underneath each distribution device 20. Each electode 25 is supported from the walls of the vessel 2 by two insulators 26, 27.

A rod 30 is disposed inside the insulator 26 and serves as a conductor for supplying the electrode 25 with electric current. The three electrodes 25 associated with the three lines 12 are connected via the rods 30 to the three phases of a three-phase AC supply network (not shown).

Collecting grids 40 are provided in the vessel 2 underneath each electrode 25. Each grid 40 consists of a frame 41 and rectangular cross-section strip steel bars 42 which are arranged parallel to each other and are mounted with their cross-sectional width vertical. The frames 41 are supported in the bottom part of the vessel 2 by legs 43.

Each distribution device 20 defines a weir arranged to permit water to flow over at least a part of the weir in unthrottled manner for all loads on the steam generator. To this end, the cone of each distribution device 20 has a rounded apex which forms a tray in the central zone 21 in which the water to be evaporated collects from the lines 12. In addition, each distribution device 20 has slots 50 which run out from the central region 21 and extend approximately radially up to the vicinity of the rim of the distribution device 20.

As shown in Fig. 2, an auxiliary slot 54 extends from each radial slot 50 in angular relation thereto and also extends to near the rim of the distribution device 20. Each slot 54 branches off from the slot 50 at about half the length of the latter. The slots 50, 54 thus to ether have a configuration in the shape of a.Six such Y-shaped arrangements of slots are distributed over the circumference of each distribution device 20 in this exemplary embodiment.

Referring to Figs. 2, 3 and 4, it will be seen that the slots 50, 54 are formed by pushing the metal out of the wall of the distribution device 20 in a downward direction in such a manner that large radii compared with the thickness of the metal are obtained on the top side and on the underside, while the rims 51 of the slots end with the sheet metal extending vertically. In order to increase the stiffness of structure around the slots, corsspieces 55 are fastened in the slots 50, 54. The dish-shaped device 20 together with the central region 21 therefore forms a weir, the overflow edge of which is defined by the edges of the slots 50, 54. The lower end of all slots 50 is at the same height. The slots do not continue all the way to the rim for reasons of strength.

As is shown in Fig. 9, the electrode 25 is also constructed as a dish-shaped distribution device 32 which has generally the same shape as the distribution device 20 and which is similarly provided with slots 50 and 54. In addition, a collecting dish 34, which is connected to the distribution dish 32 via six radial web plates 33, is arranged on the top of the electrode 25. The collecting dish 34 has a funnel-shaped outlet 35 at its centre. In addition, the collecting dish 34 is provided on top with radial fins 36 which run in from the edge of the dish 34 and extend toward the centre.

The fins 36 also serve to increase the surface area of the dish 34.

In the operation of the steam generator, water is pumped from the sump of the vessel 2, by means of the circulation pump 7, into the dish-shaped distribution devices 20, where the water at first collects in the central regions 21. If the load of the steam generator is low the circulation is kept low, and the water overflows in streams only through the lower section of the slots 50. The water falls freely from each distribution device 20 onto the collecting dish 34 of the associated electrode 25. The water is collected in the collecting dish 34 and is conducted via the funnelshaped outlet 35 to the distribution dish 32 of the electrode underneath the outlet 35. From the dish 32, the water then falls freely, again in streams to the associated collecting grid 40.The electric current flows from the electrodes 25 upwards through the falling water streams to the distribution device 20 and downwards through the falling water to the collecting grid 40. With this flow of the current, part of the flowing water evaporates and the saturated steam which is thus generated is conducted via the pipes away from the generator to a consumer not shown).

The amount of water circulated in the generator can be adapted to the prevailing steam load on the steam generator by setting the throttle 9. If the circulated quantity is large, the water level in the distribution device 20 rises to a higher level. The water then reaches the sections of the slots 50 situated further upward as well as to the lower sections of the slots 54. Thus, the total crosssection of all the water streams, which conform in cross-section to the shape of that part of the slot 50, 54 in use at any instant, increases continuously in stepless fashion.

The current drawn by the steam generator and therefore also the output of the steam generator, thereby increase continuously.

The energy converted in the steam generator increases the enthalpy of the water. Due to the "Y"-shaped arrangement of the slots 50, 54, the saturated steam produced can easily flow off to the space around the water streams without taking along substantial quantities of water.

Because of the large radius of the slots 50 and 54, as particularly shown in Fig. 3, a smooth stream of water is obtained. To make the stream flow laminar, a vertical centre web 56 which runs along the centre of the slot through the cross-pieces 55 and has about the same height as the cross-pieces 55, may be provided as is shown in Fig. 4.

As shown in Fig. 5, the dish-shaped distribution device 20 may alternatively be constructed without slots. As shown, the distribution device indicated at 20' is in the form of a shallow conical surface open toward the top with a rounded radial crosssection upper periphery 60. In this em bodiment, the water flows over the rim 60 of the distribution device 20', the cross-sectional curvature extending for this purpose over to a point where it runs approximately vertically. The distribution device 20' is mounted by means of two brackets 61 on the end of the branch line 12 which extends into the vessel 2. The associated electrode 25' located underneath the distribution device 20' con- sists of a sheet metal ring 65 of approximately S-shaped annular cross-section which, in a first part 66, runs steeply upward and is convex.In a middle part 67 of the cross-section, which follows on from the part 66, the S-shaped cross-section runs outward with a concave-convex curvature. The middle part 67 is followed by a third part 68 of the cross-section, which is directed downward and has a slightly inwardly directed frusto-conical shape. At one point of the circumference of the electrode 25', a sheet metal member 69 is provided welded onto the electrode. This sheet metal member 69 is inverted V-shaped in cross-section and has a ridge 70 that is inclined toward the section 66. The free end of the member 69 is closed off by a triangular metal plate 71 to which one end of the conductor rod 30 is fastened.

The rod 30 is surrounded by an insulator 26 as before and supports the electrode 25'.

In this embodiment, the water fed to the distribution device 20' via the branch line 12 falls as a tubular shroud from the rim 60 which forms a smooth overflow dam in the horizontal plane, onto the part 66 of the electrode 25' and then passes to the collecting grid (not shown) along the middle part 6 and the third part 68. The steam released from the water forming that shroud into the interior of the shroud flows off through a gap formed in the water shroud underneath the member 69, and thence passes to the pipe 4.

If the load on the generator changes, the length of the water shroud remains constant but the thickness of the water stream forming the shroud is changed.

If no small partial load ability is called for, an electrode 5" such as that shown in Fig.6, can also be used instead of the electrode 5'.

The annular electrode 25" consists only of a part with a convex curvature.

Fig. 7 shows a further dish-like distribution device 20", which may be used shaped as a shallow conical surface, and provided with a rim 80 which is serrated in star-fashion and defines the overflow edge of the weir formed by the all of the dish. If the load f the steam generator is small and the water level in the distribution device 20" is accordingly low, water streams of approximately triangular cross-section are produced; this cross-section being relatively small. As the load increases, the level rises and the size of the cross-section of the streams increases continuously. In general, this distribution device is constructed so that adjacent streams do not merge but gaps are left between them through which the steam within the circle of streams can flow off to the outside.Because the overflow edge offered by the serrations extends between two height levels, defined water streams are produced with very small flow rates, and as the quantity of water increases, the circumference of the crosssection of falling water becomes larger. This favours a good and safe discharge of the steam.

Fig. 8 shows how, in a further arrangement, the dish-shaped distribution device 20"' may be made similar to that of Fig. 1 but instead of having radial slots, the slots 90 in the device 20 "' are curved in involutefashion. As shown, these slots 90 run out from the central region 21"' of the distribution device and extend to near the rim of the device 20"'. An electrode 25"' of similar shape is arranged underneath the distribution device 20 'with involute-like slots displaced by half an angular pitch relative to the slots 90 m the distribution device 20"'. The out-of-phase relation of the slots in the distribution device and the electrode allows the water streams from the slots 90 to strike the electrode between each pair of slots therein.

Instead of using three electrodes as discussed above, the steam generator can be equipped with only one electrode. In this case, only one distribution device is provided above the electrode.

The invention is not limited to vessels with a horizontal axis. It is also possible to use vessels with a vertical axis. The dish-shaped distribution devices are then uniformly distributed about the axis. Similarly, the invention is not limited to distribution devices with conical dishes. Any other desired shapes are conceivable, for instance, toroidal dishes.

WHAT WE CLAIM IS: 1. An electric steam generator comprising at least one water distribution device defining a weir to permit water in said device to overflow at least a part of said weir freely for all loads of the steam generator; a variable water supply means for supplying water to said distribution device; and an electrode positioned below said distribution device to receive water overflowing said weir in free fall and conduct electric current through that water.

2. An electric steam generator as claimed in Claim 1 in which said distribution device has a shallow conical surface open towards the top to receive water from said supply means.

3. An electric steam generator as claimed in Claim 1 or 2 in which said weir is circular and is formed by a rim of said distribution device.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. toward the top with a rounded radial crosssection upper periphery 60. In this em bodiment, the water flows over the rim 60 of the distribution device 20', the cross-sectional curvature extending for this purpose over to a point where it runs approximately vertically. The distribution device 20' is mounted by means of two brackets 61 on the end of the branch line 12 which extends into the vessel 2. The associated electrode 25' located underneath the distribution device 20' con- sists of a sheet metal ring 65 of approximately S-shaped annular cross-section which, in a first part 66, runs steeply upward and is convex. In a middle part 67 of the cross-section, which follows on from the part 66, the S-shaped cross-section runs outward with a concave-convex curvature.The middle part 67 is followed by a third part 68 of the cross-section, which is directed downward and has a slightly inwardly directed frusto-conical shape. At one point of the circumference of the electrode 25', a sheet metal member 69 is provided welded onto the electrode. This sheet metal member 69 is inverted V-shaped in cross-section and has a ridge 70 that is inclined toward the section 66. The free end of the member 69 is closed off by a triangular metal plate 71 to which one end of the conductor rod 30 is fastened. The rod 30 is surrounded by an insulator 26 as before and supports the electrode 25'. In this embodiment, the water fed to the distribution device 20' via the branch line 12 falls as a tubular shroud from the rim 60 which forms a smooth overflow dam in the horizontal plane, onto the part 66 of the electrode 25' and then passes to the collecting grid (not shown) along the middle part 6 and the third part 68. The steam released from the water forming that shroud into the interior of the shroud flows off through a gap formed in the water shroud underneath the member 69, and thence passes to the pipe 4. If the load on the generator changes, the length of the water shroud remains constant but the thickness of the water stream forming the shroud is changed. If no small partial load ability is called for, an electrode 5" such as that shown in Fig.6, can also be used instead of the electrode 5'. The annular electrode 25" consists only of a part with a convex curvature. Fig. 7 shows a further dish-like distribution device 20", which may be used shaped as a shallow conical surface, and provided with a rim 80 which is serrated in star-fashion and defines the overflow edge of the weir formed by the all of the dish. If the load f the steam generator is small and the water level in the distribution device 20" is accordingly low, water streams of approximately triangular cross-section are produced; this cross-section being relatively small. As the load increases, the level rises and the size of the cross-section of the streams increases continuously. In general, this distribution device is constructed so that adjacent streams do not merge but gaps are left between them through which the steam within the circle of streams can flow off to the outside.Because the overflow edge offered by the serrations extends between two height levels, defined water streams are produced with very small flow rates, and as the quantity of water increases, the circumference of the crosssection of falling water becomes larger. This favours a good and safe discharge of the steam. Fig. 8 shows how, in a further arrangement, the dish-shaped distribution device 20"' may be made similar to that of Fig. 1 but instead of having radial slots, the slots 90 in the device 20 "' are curved in involutefashion. As shown, these slots 90 run out from the central region 21"' of the distribution device and extend to near the rim of the device 20"'. An electrode 25"' of similar shape is arranged underneath the distribution device 20 'with involute-like slots displaced by half an angular pitch relative to the slots 90 m the distribution device 20"'. The out-of-phase relation of the slots in the distribution device and the electrode allows the water streams from the slots 90 to strike the electrode between each pair of slots therein. Instead of using three electrodes as discussed above, the steam generator can be equipped with only one electrode. In this case, only one distribution device is provided above the electrode. The invention is not limited to vessels with a horizontal axis. It is also possible to use vessels with a vertical axis. The dish-shaped distribution devices are then uniformly distributed about the axis. Similarly, the invention is not limited to distribution devices with conical dishes. Any other desired shapes are conceivable, for instance, toroidal dishes. WHAT WE CLAIM IS:

1. An electric steam generator comprising at least one water distribution device defining a weir to permit water in said device to overflow at least a part of said weir freely for all loads of the steam generator; a variable water supply means for supplying water to said distribution device; and an electrode positioned below said distribution device to receive water overflowing said weir in free fall and conduct electric current through that water.

4. An electric steam generator as

claimed in Claim 3 in which the radial crosssection of said rim is rounded in a downward direction and extends to a point where it runs approximately vertically.

5. An electric steam generator as claimed in Claim 1 or 2 in which said weir is generally circular and is formed by a starshaped serrated rim of said distribution device.

6. An electric steam generator as claimed in Claim 1 or 2 in which said distribution device has a plurality of generally radial slots extending rom a rim of said device towards the centre of said device, the slots defining said weir.

7. An electric steam generator as claimed in Claim 6 in which said distribution device has a plurality of auxiliary slots, each said auxiliary slot extending from a repsective radial slot in angular relation thereto.

8. An electric steam generator as claimed in Claim 1 or 2 in which said distribution device has a plurality of involutelycurved slots extending from a rim of said device towards the centre of said device the slots defining said weir.

9. An electric steam generator substantially as herein described with reference to Figures 1, 2,3,4, 5 and 9, Figure 5, Figure 6, Figure 7 or Figure 8 of the accompanying drawings.