US2705217A

US2705217A - Constant flow device for a water still

Info

Publication number: US2705217A
Authority: US
Inventors: Canicoba Saul
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-01-18
Filing date: 1951-01-18
Publication date: 1955-03-29
Anticipated expiration: 1972-03-29

Description

March 29, 1955 Filed Jan. 18. 1951 S. CANICOBA CONSTANT FLOW DEVICE FOR A WATER STILL 4 Sheets-Sheet 1 V. j 55 I 41 2 14- z 7 f 10 r9 4 1/4 I 15 INVENTOR I \S (70!. N/COB,

March 29, 1955 CANICOBA 2,705,217

CONSTANT FLOW DEVICE FOR A WATER STILL Filed Jan. 18, I951 4 Sheets-Sheet 2 J5 64 14 65 J26, a 7 61 H 1,. 59 7 10 60 5X 5 956 9 102 7 5 J 5 J fli (71 9/ 90 92 March 29, 1955 s CANIQQBA- 2,705,217 I CO NSTANT FLOW DEVICE FOR A WATER STILL Filed Jan. 18, 1951 4 Sheets-Sheet 3 57 f N 5M MENTOR.

IZZQRQW March 29, 1955 s. CANICOBA 2,705,217 CONSTANT FLOW DEVICE FOR A WATER STILL Filed Jan. 18. 1951 5/404 C/iN/COB,

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4 Sheets-Sheet 4 United States Patent 2,705,217 CONSTANT FLOW DEVICE FOR A WATER STILL Saul Canicoba, Buenos Aires, Argentina Application January 18, 1951, Serial No. 206,696 4 Claims. (Cl. 202-185) This invention refers to improvements in distilling apparatus and more particularly it relates to a new water still of the continuous production type.

The known stills of the type herein concerned mainly comprise a boiler provided with a heating means fixed thereto, a condenser partially housed in said boiler and provided with means for collecting the steam produced by said boiler. The condenser is generally made of a metal pipe and the part emerging out of the boiler is surrounded by a jacket into which water is introduced for cooling purposes, said water being then conducted into the boiler for distilling purposes. The length of the condenser tube is in direct relationship with the speed of flow of the water in the jacket so that said water will usually enter into the boiler at a temperature which is near the boil ing point. I It will be appreciated that any change in the flow rate, which often happens due to pressure variations in the source of fluid, will act immediately on the production efficiency of the still because the water will enter at a different temperature in the boiler.

Another drawback resides in the fact that by using metal pipes in order to obtain a high heat interchanging coefiicient, the distilled water contains usually certain metal salts which must be eliminated later on. The heating means above referred to is generally made of a suitable insulated electrical resistance fixed to said boiler and in contact with the water, the terminals of said resistance emerging out of the boiler. Said resistance has a relatively short life, mostly due to short circuits, so that upon such a failure the whole equipment must be stopped, cooled and dismounted in order to replace the resistance by a new one.

The apparatus hereinafter described has overcome all the drawbacks pointed out above and provides at the same time several further advantages which will be apparent in the course of the following description.

In order to assure a constant production efliciency of the apparatus of this invention a constant flow device is provided which controls the flow of the cooling water through the jacket. Said constant flow device is furthermore provided with means for controlling the heating means, so that when the water supply falls below a predetermined limit, the electrical current supply to the heating means is interrupted.

The heating means is of a special structure and so arranged in the boiler that upon any failure of the former it can be quickly replaced by a new one without requiring all the operations previously pointed out.

The condenser tube is preferably made of thin glass in order to obtain the highest possible heat exchanging coeificient and at the same time substantially to prevent the appearance of any trace of metal salts in the resulting distilled water.

Moreover it has been found that by using the still of this invention the purity of the water obtained by a single distillation corresponds to that of an distilled water. It is not quite clear why such a favorable result is obtained but it seems that the arrangement of the different parts and the very even functioning of the apparatus are the basis therefor.

From the above discussion, it can be appreciated that one of the objects of the present invention is to provide a new still of the continuous production type wherein a constant flow device for the water supply exists, so that a high production efficiency is assured.

ordinary doubly 2,705,211 Patented Mar. 29, 1955 Another object is to provide a constant flow device for the still of this invention which is furthermore provided with means for controlling the electric circuit of the heating means arranged in the boiler of the still.

Still another object is to provide a jacket for the condenser which is partially housed in the boiler and pro vided with a preheating chamber in order to assure that the temperature of the cooling water is raised almost to the boiling point before entering the boiler, and furthermore a special channel relates said preheating chamber with a constant level device connected to a sink, thereby tending to maintain a constant level in the preheating chamber and discharging the cooling water surplus to the sink before it can reach the preheating chamber so that no unnecessary energy is wasted for the surplus cooling water.

Another object is to provide a glass condensing tube so arranged in a metal jacket that the unequal lengthening due to variation in heat of the glass condenser and'metal jacket will not produce any stresses between the two members in spite of their being connected together.

A further object resides in providing a heating means independent with regard to the rest of the apparatus which can be easily replaced in the boiler without requiring the discharge of the water from the boiler and the preheating chamber or cooling down the apparatus.

Another object consists in providing an electric re sistance so arranged, that it can be used for two-phase and three-phase current without requiring any modification in the apparatus with the exception of one wire con nection which operation represents no difficulty.

These and further objects and advantages will become clear in the course of the following description in which one specific embodiment has been illustrated by way of example.

In the drawings:

Fig. 1 is a side elevation of a water still of the continuous production type in accordance with the present invention.

Fig. 2 is a longitudinal part-sectional view of the still shown in Fig. 1.

Fig. 3 is a longitudinal section in a plane perpendicular to the plane of Fig. 1, of the constant flow device on a larger scale.

F Fig. 4 is a cross-sectional view along line IVIV of Fig. 5 is a rear perspective view of the heating means.-

Fig. 6 is a front elevation of the head with the electrical terminals of the heating means.

Fig. 7 represents the electrical circuit of the heating means in parallel arrangement.

Fig. 8 represents the electrical circuit of the heating means in a series arrangement.

As may be seen in Fig. 1 the still 1 is supported by wall 2, in this particular instance at a corner and wall 3 supports a cock 4 connected to a source of water, and a sink 5 for discharging the water surplus. Wall 2 is provided with a plug 6 connected to a source of electric current.

The still 1 comprises a constant flow device 7, a constant level and discharge device 8, a boiler 9 covered by a sealing cover 10 which supports an electric heating means 11 in functional relationship with the constant flow device 7. A metal jacket 12 surrounds a condenser tube of which only the lower end 13, and the upper end 14 are visible in Fig. 1.

The constant flow device 7 is connected to the cock 4 by means of a flexible tube 15 and metal duct 16 delivers the cooling water from the constant flow device 7 towards the lower end of metal jacket 12.

Conduit 17 connects the inside of boiler 9 with discharge device 8 through discharge valve 18.

The constant flow device 7 is provided with means 19 for controlling the current supply to the electric heating means 11.

Having thus given a general description of the main parts of the still of this invention, the several important features will now be analysed separately.

The constant flow device 7 (see Figs. 3 and 4) comprises a water admission chamber 20, a constant flow feeding chamber 21 and a surplus discharge chamber 22. The constant flow feeding chamber 21 is limited by part1t1on

walls constituting weirs

23 and 24 of equal height but smaller than the contour wall 25 which defines the

outer chambers

20 and 22 as well as the constant flow device 7 per se. Said contour wall 25 is provided with supporting ears 26 which enable the constant flow device 7 to be fastened by means of screws 27 to fixing plate 28 (see also Fig. 1) forming part of the constant level and discharge device 8 which supports the whole still and to which end holes 115 are provided for fastening the still to wall 2.

A nipple 29 arranged near the base of water admission chamber 20 provides the necessary connecting means be tween said water admission chamber 20 and cock 4 by means of flexible tube 15 (see also Fig. 1).

The constant flow feeding chamber is connected through a suitable coupling 30 arranged at the base of said chamber to metal duct 16. A float 31 is slidably housed in said constant flow feeding chamber 21 and provided with an upwardly emerging stem 32 connected to means 19 for controlling the current supply to the electric heating means 11 as already previouslv stated, and which means 19 will be later explained. The float 31 is of the cylindrical type and therefore, as can better be understood from Fig. 4, the water which is delivered to water admission chamber 20, can easily penetrate into the constant flow feeding chamber 21 upon overflowing the upper end of partition wall 23 by passing through spaces 33 existing between the side wall of float 31 and the wall of said constant flow feeding chamber 21.

The surplus discharge chamber 22 arranged adjacent to the constant flow feeding chamber has a base with a bore in which a discharge conduit 34 is mounted the free end of which is directed towards discharge device 8 as can be seen in Fig. 2.

From the preceding description the functioning of the constant level device 7 can already be conceived. In fact, water supplied from the source through cock 4, flexible tube 15 and nipple 29 will enter the lower part of water admission chamber 20 and the air bubbles will immediately rise whilst the water level itself will rise more slowlv until it reaches the upper free end of partition wall 23 and when it reaches said upper end, the water will overflow in a relatively steadv manner so that upon entering into constant flow feeding chamber 21 through spaces 33 very little disturbance exists. The water supply should be a little larger than the normal water discharge throu h metal duct 16 so that float 31 is substantially maintained in the position shown in Fig. 3. Under normal conditions a constant flow is thereby ensured and at the same time a constant pressure. because the hei ht of the water column in the onstant flow feeding chamber is maintained constant. The surplus of water passes to sur lus discharge chamber 22 where it will be dischar ed throu h discharge conduit 34. In order to facilitate the understanding. several arrows show the flow directi n of the water. If the water supply is increased no effect will be noticed in the c nstant flow of the water passing throu h metal duct 16. but merely an increase of water in the dischar e conduit 34 will exist, so that nothing will be m dified with re ard to the normal functioning of the still from this viewpoint. On the other hand if the water supplv decreases to such an extent that the pressure of the water column existing in the constant flow feeding chamber 21. varies substantially with respect to the normal functionin of this still, then automaticallv the electric current supplv is interrupted by means of float 31 which obviouslv will descend in the constant flow feeding chamber 21 and therebv operate on means 19 for controllin he electric circuit. which means 19 will now be descri ed.

A plate 35 of insulating material is supported by pro jecting ribs 36 and screws 37. On said plate 35 a mercury switch 38 is arranged which consists of an L-shaped support 39, swingable about pivot 40 and sup orting a glass bulb 41 bv means of clamps 42. Said glass bulb 41 is partially filled with mercurv and is provided in its interior with two platinum rings 43 and 44 separated from each other and provided with connecting wires passing through said bulb 41 to the exterior where the ends of said wires are connected to

insulated wires

45 and 46, respectively, the other ends of which are fixed to binding

screws

47 and 48, respectively. A $09 4? $9.

port 39 is also provided in order to limit the upward movement of float 31, and prevent at the same time that the float 31 can leave chamber 21.

The operation of the mercury switch 38 is quite simple since the mercury contained in bulb 41 is capable of establishing a conducting bridge between platinum rings 43 and 44, when float 31 is in the upper portion of the constant flow feeding chamber 21. When float 31 moves downwardly the mercury in the bulb 41 will displace itself towards the end adjacent to stem 32 and thereby destroys the conducting bridge between platinum rings 43 and 44, whereby the circuit is interrupted.

The insulating plate 35 is furthermore provided with

binding screws

50 and 51. A bridge 52 connects on the rear

face binding screws

47 and 51. Binding

screws

50 and 51 are connected to plug 6 (see Fig. 1) through twin cable 53.

Insulated wires

54 and 55 are connected respectively to binding

screws

48 and 50 and feed the current to the electric heating means 11 as will be later more detailed explained.

As may be best seen in Fig. 2 the still 1 itself consists of a cup shape outer carcase 56 having a central opening 57. Said carcase 56 constitutes a support for an inner container 58 having a flange 59 gripped around the upper circular edge of outer carcase 56. Outer carcase 56 and inner container 58 constitute the boiler 9. The inner container 58 is conveniently formed of two pieces riveted and welded together at the bottom part as can be appreciated in the figure. A circular bulge 60 constitutes a supporting platform for cover 10 formed of a cylinder 61 with a base ring 62 resting on said bulge 60 and provided at its upper end portion with a support 63 for a glass cupola 64 fastened to the cylinder 61 between the support 63 and the upper rim 65 of said cylinder 61.

The inner container 58 has a central opening coaxial with central opening 57 and provided with a rubber sealing and supporting ring 66 through which condenser 67 passes.

The constant level and discharge device 8 which is usually a casting has to be the most robust part because it actually supports the complete apparatus. The fixing plate 28 constitutes the back wall of discharge chamber 68 in alinement with surplus discharge chamber 22 of the constant flow device 7.

The base of the discharge chamber 68 is provided with a discharge duct 69 connected to flexible tube 70 which leads the surplus water to waste for example to sink 5 (see Fig. 1). Conduit 17 which connects the inside of inner container 58 with discharge chamber 68 enables the water existing in said container 58 to be discharged when the still is not to be used. Discharge valve 18 suitably controls said duct 17.

One side of the discharge chamber 68 is defined by a weir 71 forming with wall 72 the leveling chamber 73, the base of which forms part of an interconnecting duct 74 the other end of which is connected to a cylindrical body forming preheating chamber 75 coaxially arranged with central opening 57 and rubber sealing and supporting ring 66. Said preheating chamber 75 is in communication with atmosphere through channel 94 and central opening 57. The condenser tube also passes through said preheating chamber 75. The broken line 76 indicates the water level which will exist in the preheating chamber 75 and inner container 58 during normal operation due to the weir 71 connected to preheating chamber 75 through interconnecting duct 74. Adjacent to and underneath level 76 a bore 77 connects said preheating chamber 75 with the inner container 58.

Interconnecting duct 74 is provided with several ears 78 for fixing, by means of screws, both the inner container 58 as well as the outer carcase 56 to said interconnecting duct 74, which is the main support for boiler 9.

In order to give the assembly a greater rigidity, outer wall 72 is connected to carcase 56 by plates 79 (see also Fig. 1).

The cylindrical body of preheating chamber 75 supports at its lower end, metal jacket 12 which is screwed into said cylindrical body. The lower end of said metal jacket 12 is provided with a cup shaped member 80 having a central opening, and two projections 89 on which tension springs 90 are fastened.

Condenser tube 67 is housed partially in said metal jacket 12 and supported by conical rubber plug 81 at '5 the lower end portion and rubber sealing and supporting ring 66 at the upper portion.

The condenser tube 67 comprises at its upper end, which is housed in the steam containing chamber formed by the boiler 9 and the sealing cover 10, an outer cup shaped member 82 the base of which is provided with a draining tube 83 and an inner inverted cup shaped member 84, concentric with the outer cup shaped member 82 and supported in spaced relationship by means of spacing rods 85. The inner inverted cup shaped member 84 has a dome base and is spaced away from the cylindrical steam collecting duct 86. The arrangement 80, 8286 described, constitutes an improved steam trap. In fact the steam produced by the boiler, which will be later explained, enters through the upper open end into the outer cup shaped member 82 and any water drops which have been entrained will be returned to the boiler through training tube 83 when the steam changes its direction of flow. However, it sometimes happens that certain water particles are not eliminated by this first sudden change of direction of flow, and a condensate in the form of water drops can be noticed on the base of the inverted cup member 84. In view of the fact that said base is dome shaped, the condensate will find its way back to the outer cup member 82 and draining tube 83. In the steam traps formerly used the base or bottom of the inverted cup shaped member was flat and thereby some of the condensate or water drops dropped into the condensing tube and thus the quality of the distilled water was changed.

The steam collecting duct 86 merges into a second duct portion 87 of larger diameter which portion is arranged in the preheating chamber 75. The steam which penetrates into the steam collecting duct 86 has practically not lost any of its latent the second duct portion 87 because the cylindrical steam collecting duct 86 is surrounded by steam. As will be later explained, this latent heat existing in the steam when passing through the second duct portion is used in the preheating chamber for raising the temperature of the cooling water substantially up to the boiling point.

The condensing tube 67 consists furthermore of interconnected sphere shaped portions 88 which should be made as thin as possible in order to increase the heat exchanging coefficient between the condensing steam passing downwardly through condenser tube 67 and the cooling water rising in metal jacket 12 as will be further on explained. The sphere shaped portions 88 provide the largest contact surface possible in a given space so that by adopting this shape the heat exchanging coefiicient is also increased.

The lower end 13 of condenser tube 67 is of frustoconical shape the larger base corresponding to the free end 13 of the condenser tube. The conical rubber plug 81 mounted on the lower end 13 of the condenser tube is an inversely conical plug, with regard to the frustoconical shape of the lower end 13, whereby a selffastening action between the cup shaped member of the metal jacket 12 and the condenser tube 67 is obtained. In fact, if due to variation in temperature a difference in elongation between the metal jacket 12 and the condenser tube 67 is produced, condenser tube 67 tends to move upwardly or decrease its length with regard to the metal parts, thereby pressing rubber plug 81 against opening of cup shaped member 80. The relative movement of the condenser tube 67 is performed at the upper end or in other words rubber sealing and supporting ring 66 will permit a slight displacement of condenser tube 67 with regard to the metallic parts.

The lower end 13 of condenser tube 67 is conveniently connected to a delivering tube 91 having a corresponding frustoconical upper end to fit into the lower end 13 of condenser tube 67. It is furthermore provided with two projections 92 to which the springs are fastened in order to maintain the delivery tube 91 in its proper position. A cover 93 is integral with the delivery tube 91 in order to prevent strange particles from entering into the flask or tank into which the delivery tube discharges the condensate, and also to avoid that water spilling over from the boiler, which will be later explained, enter the flask.

The electric heating means 11, see Figs. 5, 6 and also Fig. 2, consists of a hollow metal case 95 having at its lower end connected thereto two

helical tubes

96 and 97 which form a cylindrical body.

heat when entering into The hollow metal case 95 has a circular projection 98 provided with a screw thread 99 on which two rings 100 and 101 are threaded (see Fig. l). The cylinder 61 is provided with a suitable opening through which projection 98 may pass and rings 100 and 101 are designed to clamp therebetween a corresponding portion of the cylinder 61 to fasten the heating means 11 thereto and situate it in the boiler. In order to seal the opening wherein the circular projection 98 of the hollow metal case 95 is mounted, a packing ring or the like (not shown) is mounted therebetween.

The

helical tubes

96 and 97 are so arranged that when the heating means 11 is mounted in the boiler they are concentrical with the condensing tube 67. The height of the heating means 11 should be so designed that the lowest portion of helical tube 96 is situated adjacent the bottom of the inner container 58 but substantially not in contact therewith and the uppermost portion of helical tube 97 is not above the rubber sealing and supporting ring 66 or even better above level 76. In the hollow case 95 and helical tube 96 connected thereto an electrical resistance 102 is arranged which is surrounded by refractory material 103. Similarly an electrical resistance 104 is arranged in metal case 95 and helical tube 97. The electrical resistance 102 has two terminals 105 and 106 (see Figs. 6 to 8) which project out of projection 98 and are fastened to binding

screws

107 and 108 respectively, which binding screws are partially embedded in the refractory material 103; similarly, resistance 104 has outwardly projecting

terminals

109 and 110, which are fastened to binding

screws

111 and 108, respectively.

A bridge 112 (Figs. 6 and 7) connects terminal 105 to 109 through

binding screws

107 and 111.

Insulated wires

54 and 55 connect the electrical resistances with the mercury switch 38.

As may be seen in the electrical circuit diagrams of Figs. 7 and 8 the connections may be carried out in two manners. The arrangement of Fig. 7 corresponds to that shown in the remaining drawings or in other words

electrical resistances

102 and 104 are parallel. In fact, the power supply source 113 is connected to the apparatus through twin cable 53 one Wire of which is connected to binding screw 50 whilst the other is connected to binding screw 51. The electric current flow is as follows: power supply source 113 through conduit 53 to binding screw 51, to bridge 52, to binding screw 47, to platinum ring 43 through mercury bridge to platinum ring 44, through insulated wire 46 to binding screw 48, through insulated wire 54 to

binding screw

107 and 111 by means of bridge 112. From binding

screws

107 and 111 in parallel arrangement through

heating resistance

102 and 104 to binding screw 108 and from binding screw 108 back to binding screw 50 through insulated wire 55 and back to the supply source 113 by means of the other conduit 53.

In order to obtain the circuit shown in Fig. 8, it is only necessary to eliminate bridge 112 by loosening binding screws 107 and 111 (see Fig. 6), thereby the series arrangement is obtained which operates as follows: from power supply source 113 to conduit 53, binding screw 51, bridge 52, binding screw 47, wire 45, platinum ring 43, mercury bridge, platinum ring 44, wire 46, binding screw 48, wire 54, binding screw 111, resistance 104, binding screw 108, resistance 102, binding screw 107, wire 55, binding screw 50 and back to the supply source 113 through the other wire of twin cable 53.

In view of the fact that the several parts integrating the still of this invention have already been described individually both with respect to structure as well as to function, the operating and functioning of the still as a whole will be readily understood, by the following brief description.

Water is supplied through cock 4, flexible tube 15 to the constant flow device 7 which once in normal operation by means of the means 19 for controlling the electric circuit will close the latter and thereby supply electric current to the

resistances

102 and 104 whilst water enters through metal duct 16 into metal jacket 12 passing through bore 77 into inner container 58 wherein steam is generated. The steam is collected by the cylindrical steam collecting duct 86, previously passing through the corresponding steam trap and said steam will descend through the condensing tube 67 wherein it will be condensed and discharged through delivery tube 91. The condensation takes place in the sphere shaped portions 88 by heat interchange between the cooling water rising in metal jacket 12 and the condensing steam descending in condensing tube 67. It will thereby beunderstood that the cooling water which enters at the bottom portion into metal jacket 12 will at that height be practically at 75 F. and the condensate in the condenser 67 at that height will have practically the same or a slightly higher temperature. The higher the cooling water rises in the metal jacket 12, the higher its temperature will be. Similar considerations are applicable to the condensate.

It is obvious that a greater amount of cooling water is necessary than steam is produced in the boiler, so that the surplus of cooling water must be eliminated. To this effect interconnecting duct 74 communicates the preheating chamber 75 at the lower end thereof with the constant level and discharge device 8 through leveling chamber 73. Thereby a constant level is obtained both in the preheating chamber and in the inner container 58 and water will only pass into the inner container 58 in the same measure as steam is evacuated through condenser 67. In view of the fact that the water will remain a certain time in the preheating chamber, its temperature will almost rise to 212 F. because as already previously explained, the steam passing through the secondduct portion 87 has not as yet transferred any of its latent heat. a

This preheating chamber eliminates also the gases and air bubbles existing in the cooling water there stationed, because upon heating the water up to practically the boiling point, the air and gases will rise and pass through channel 94 and central opening 57 to the atmosphere. Thereby the water which enters into the boiler is practically free of gases and air and thus a first purification has already taken place.

It is possible that in the preheating chamber together with the air and gases which exit through channel 94 and central opening 57, a certain amount of water overspills which will then run along the outer surface of metal jacket 12. In order to avoid that said water enter into the collector of the distilled water, a cover 93, as already previously explained, is integral with delivery tube 91.

It is obvious that if a short circuit exists in the resistance it is only necessary to dismount the sealing cover by loosening screws 114 (only one being visible in Fig. 1) and unscrewing ring 100 to be able to interchange the heating means 11 for a new one and thereafter again mount the sealing cover 10 on the rest of the apparatus without requiring practically any interruption of the functioning of the still.

It is obvious that the most important feature concerning the heating means 11 is that they are supported by the sealing cover 10, and instead of mounting the assembly on the cylindrical body 61 it could be as well fixed to the glass cupola 64, for instance.

The water existing in the boiler at the level indicated by dotted line 76 provides also a hydraulic sealing between the inner container 58 and the cylindrical body 61 and thereby a perfect closure is assured.

If the

electric resistances

102 and 104 are damaged, such as by a short circuit, obviously the steam production will stop and consequently no distilled water will be discharged by delivery tube 91. The cooling water will run through the surplus flow circuit, or in other words the water delivered by cock 4 will pass through flexible tube 15, constant flow device 7, metal duct 16, metal jacket 12, interconnecting duct 74, leveling chamber 73, Weir 71, discharge chamber 68, discharge duct 69, flexible tube 70, to sink 5.

When the operator notices that no distilled water is discharged by delivery tube 91 he should first check if the water supply is interrupted, by observing the position of mercury switch 38 and stem 32. If the water supply is normal then the

resistances

102 and 104 must be damaged which however he can test in the manner known to those skilled in the art. The replacement of the electric heating means 11 has already been explained.

The fact that metal case 95 is situated above water level line 76 represents several advantages over the heating means used in the apparatus known in the art. In fact the welding between

tubes

96 and 97 and the bottom part of metal case 95 is situated above the water level Whilst the welding of the tube in the known apparatus is beneath the water level and therefore pores which may be present in the welding and which are temporarily covered by borax, for instance, which is gradually washed out, will permit the entrance of Water and thereby produce a short circuit.

Another advantage of the structure as described resides in the fact that

terminals

105, 106, 109 and 110 as well as binding

screws

107, 108 and 111 are above the water level so that any overspilling will not wet the contacts and cannot produce a short circuit as happens in the known devices wherein usually said terminals and binding screws are situated below the water level.

I claim:

1. In combination with a water still of the continuous production type having an evaporating chamber and a leveling device communicating with said evaporating chamber, a constant flow device providing a uniform flow of cooling water, said constant flow device comprising a water admission chamber, a surplus discharge chamber and a constant flow feeding chamber separating said first two chambers, each of said chambers having a bottom portion, said water admission chamber being provided at its bottom portion with means for connecting said water admission chamber with a source of water, a first partition wall separating said admission chamber from said constant flow feeding chamber, a second partition wall of substantially the same height as said first wall separating said constant flow feeding chamber from said suiplus discharge chamber, said first and second partition walls forming connecting weirs between the respective chambers, said chambers being open to atmosphere, said constant flow feeding chamber and said surplus discharge chamber being each provided with a discharge opening at their bottom portion.

2. In combination with a water still of the continuous production type having a boiler provided with an electric heating resistance for producing steam in said boiler and a condenser for condensing said steam by means of cooling water, part of which is used for distilling purposes while the rest is discharged to waste, a constant flow device for delivering to said boiler a constant uniform flow of cooling water, said constant flow device being a container divided into a water admission chamber, a surplus discharge chamber and a constant flow feeding chamber located between said first two chambers, said chambers being separated from each other by two partition walls of substantially the same height and of smaller height than that of the container, said chambers open to atmosphere, each having a bottom portion provided with an opening, said partition walls constituting weirs communicating said water admission chamber with said constant flow feeding chamber respectively, and said constant flow feeding chamber with said surplus discharge chamber, said constant flow feeding chamber being provided with electric current supply controlling means for said electric heating resistance, which controlling means are responsive to variations of the water level in said constant flow feeding chamber.

3. In combination with a water still of the continuous production type having a boiler provided with an electrical heating resistance for producing stem in said boiler and a condenser for condensing said steam by means of cooling Water, part of which is to be distilled while the rest is discharged to waste, a constant flow device for providing a uniform fiow of cooling water, said constant flow device being a container divided into a water admission chamber, a surplus discharge chamber and a constant flow feeding chamber disposed between said first two chambers, said chambers being separated from each other by two partition walls of equal height but smaller than the height of the container, said chambers being open to atmosphere, each having a bottom portion provided with an opening, said partition walls constituting weirs communicating said water admission chamber with said constant flow feeding chamber, and said constant flow feeding chamber with said surplus discharge chamber, respectively, a float slidably mounted in said constant flow feeding chamber and provided with a stem and connected to a swingablc mercury switch for controlling current supply to said electric heating resistance.

4. A water still of the continuous production type comprising a boiler; a leveling device having a discharge outlet; means forming a communication between said boiler and said leveling device; a condenser; a supply of cooling water for said condenser; means forming a flow path for said cooling water around said condenser and into said communicating means between said boiler and said leveling device, whereby a portion of said cooling water flows into said boiler and the remainder flows through said leveling device to discharge; and a constant flow device providing a uniform flow of cooling water; said constant flow device comprising a water admission chamber; a surplus discharge chamber, and a constant flow feeding chamber separating said first two chambers, each said chambers having a bottom portion, a first partition wall separating said admission chamber from said constant flow feeding chamber, a second partition wall substantially of the same height as said first wall separating said constant flow feeding chamber from said surplus discharge chamber, said first and second partition walls forming connecting weirs between the respective chambers, said chambers being open to atmosphere, said water admission chamber being provided at its bottom portion with supply means having a discharge opening for connecting said water admission chamber with said supply of cooling water, said discharge opening of said supply means facing said first partition wall, said constant flow feeding cham- References Cited in the file of this patent UNITED STATES PATENTS Barnstead July 28, 1891 Girouard July 23, 1901 Rochlitz Oct. 11, 1904 Edelen June 8, 1909 Wagner May 10, 1921 Jack June 21, 1932 Palmer Sept. 15, 1936 Poirier June 11, 1940 Rickmeyer Sept. 30, 1941

Claims

1. IN COMBINATION WITH A WATER STILL OF THE CONTINUOUS PRODUCTION TYPE HAVING AN EVAPORATING CHAMBER AND A LEVELING DEVICE COMMUNICATING WITH SAID EVAPORATING CHAMBER, A CONSTANT FLOW DEVICE PROVIDING A UNIFORM FLOW OF COOLING WATER, SAID CONSTANT FLOW DEVICE COMPRSING A WATER ADMISSION CHAMBER, A SURPLUS DISCHARGE CHAMBER AND A CONSTANT FLOW FEEDING CHAMBER SEPARATING SAID FIRST TWO CHAMBERS, EACH OF SAID CHAMEBRS HAVING A BOTTOM PORTION, SAID WATER ADMISSION CHAMBER BEING PROVIDED AT ITS BOTTOM PORTION WITH MEANS FOR CONNECTING SAID WATER ADMISSION CHAMBER WITH A SOURCE OF WATER, A FIRST PARTITION WALL SEPARATING SAID ADMISSION CHAMBER FROM SAID CONSTANT FLOW FEEDING CHAMBER, A SECOND PARTITION WALL OF SUBSTANTIALLY THE SAME HEIGHT AS SAID FIRST WALL SEPARATING SAID CONSTANT FLOW FEEDING CHAMBER FORM SAID SURPLUS DISCHARGE CHAMBER, SAID FIRST AND SECOND PARTITION WALLS FORMING CONNECTING WEIRS BETWEEN THE RESPECTIVE CHAMBERS, SAID CHAMBERS BEING OPEN TO ATMOSPHERE, SAID CONSTANT FLOW FEEDING CHAMBER AND SAID SURPLUS DISCHARGE CHAMBER BEING EACH PROVIDED WITH A DISCHARGE OPENING AT THEIR BOTTOM PORTION.