US3204687A - Centrifugal electrical apparatus for treating liquids - Google Patents

Description

Sept. 7, 1965 R. G. SARGEANT 3,204,687

CENTRIFUGAL ELECTRICAL APPARATUS FOR TREATING LIQUIDS Filed July 23, 1963 2 Sheets-Sheet 1 HIGH FREQUENCY ELECTRODE TO VACU ELECTRODE FREQUENCY GENERATOR 3 INVENTOR Ru I ph G. Sergeant ATTORNEY Sept. 7, 1965 R. G. SARGEANT CENTRIFUGAL ELECTRICAL APPARATUS FOR TREATING LIQUIDS Filed July 23, 1965 2 Sheets-Sheet 2 5 It 3 I- m m E M Ralph G. Sarge-ant W! mm m m FIG.6.

ATTORNEY United States Patent 3,204,687 CENTRIFUGAL ELECTRICAL APPARATUS FOR TREATING LIQUIDS Ralph G. Sargeant, 408 W. Windsor St., Lakeland, Fla. Filed July 23, 1963, Ser. No. 297,086 12 Claims. ('Cl. 159-6) This invention relates to apparatus for evaporating, concentrating or otherwise treating liquids, and more particularly to centrifugal apparatus of this character, combined with means for subjecting the liquid to the action of electrical energy.

While the invention is applicable to liquids or liquid mixtures in general, it has special advantages when used in the treatment of fruit juices.

In the concentration of fruit juices, it has been common practice for many years to cause the juices to flow by gravity through a group of vertical tubes surrounded by a heating medium such as steam, in order to heat the juices before discharging them into an evaporating chammethod, however, has been the fact that the juices, trickling down the hot tubes, form a film which adheres to the tube walls, and builds up in thickness until it eventually fills up or closes the tubes. It has also been the common practice to carry out this evaporation method in successive stages, the partially concentrated juice from the first stage being fed into the second stage, and that discharged from'the second stage being fed into the third stage, and

so on, until the desired density is reached. However, it

has been found that the above mentioned clogging of the tubes increases rapidly with the density, and it is generally conceded that this type of evaporator becomes practically inoperative above a density of 50 to 55 Brix.

One object of the invention is therefore to devise a tube-type heat exchanger in which gravity is not depended upon to cause the flow of liquid through the tubes but in which the liquid is driven through the tubes by centrifugal force. In this way the formation of film and the building up of material in such manner as to clog the tubes is practically prevented.

' In my prior Patent No. 3,060,297 dated October 23, 1962, I have disclosed and claimed apparatus for removing water from liquid mixtures, this apparatus including a vertical evaporating chamber into which the liquid was .20 her, under partial vacuum. A great drawback to this "ice liquid flowing through the same, at moderate temperatures. Owing to the relatively large amount of energy being transmitted, the conductor connected with the central electrode tends to become hot, and this heat is transferred by conduction and radiation to the electrode structure, thus unduly raising the temperature thereof. To prevent this, the said conductor is shown in my said prior patent as a water-cooled tube.

I have now discovered that undue heating of the electrode structure and the mass of liquid therein can be prevented without recourse to water cooling of the conductor. I have found that the desired result can be accomplished by forming the conductor in two sections, one being connected with the electrode and the other being connected with the generator, the two sections being disposed in end-to-end relation, with an air gap between them. The high frequency, high voltage electrical energy can readily flow across this gap, but the transmission of heat from one section to the other is substantially prevented by said gap. Thus, the section connected with the electrode remains relatively cool.

In order that the invention may be readily understood, reference is had to the accompanying drawings forming part of this specification and in which:

FIG. 1 is a vertical section through one form of my improved apparatus, parts being shown in elevation and v parts being broken away;

FIG. 2 is a horizontal section substantially on the line 2--2 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a transverse section on the line 3-3 of FIG. 2 looking in the direction of the arrows;

FIG. 4 is a view similar to FIG. 1 but showing a modified arrangement;

FIG. 5 is a fragmentary detail on an enlarged scale showing some of the parts included in FIG. 4; and

FIG. 6 is a fragmentary side elevation showing a modified arrangement which is applicable to either FIG. 1 or FIG. 4.

Referring to the drawings in detail and more particularly first to FIG. 1, my improved apparatus comprises an evaporating chamber 1 having a sloping bottom 2 and connected with a vapor exhaust pipe 3. This pipe leads to a condenser and vacuum pump of any suitable type,

introduced and from the bottom of which it was recycled by a pump to the top thereof. In this patented apparatus, I subjected the liquid being recycled to theaction of high frequency electrical energy by causing the same to flow through a special electrode structure.

Another object of the present invention is to provide means whereby the fresh, incoming liquid is subjected to the action of high frequency electrical energy before reaching the evaporator, in addition to while it is being recycled.

Still another object is to devise a novel means of subjecting the liquid to the action of high frequency electrical energy, operating on a principle entirely different from that of the patented electrode structure. In this way I can utilize, in connection with my improved centrifugal arrangement, either my novel electrical energy applying means or the electrode structure, or both, as may be desired.

The electrode structure shown in my said prior patent comprises a cylindrical casing having a rod-shaped central electrode extending into it, this electrode being sup ported at one end of the casing by and projecting through a suitable insulator. A conductor from a high frequency generator is connected to the projecting end of the electrode. In most applications of the apparatus, especially when treating heat-sensitive liquids such as fruit juices, it is important to keep the electrode structure and the such as shown in my said prior patent.

Mounted Within the evaporating chamber is a heat exchanger unit comprising a closed cylindrical container 4 having ahopper shaped bottom 5 and mounted for rotation about a vertical axis. Rigid with the container 4 at the center thereof is a vertical pipe 6 extending through the top wall of the evaporating chamber and through a combined seal and bearing 7. A pipe 8 connects with the top of pipe 6 through a suitable stuffing box 9.

At the bottom of the container is a discharge pipe 10 passing through a combined seal and bearing 11. This pipe is joined by means of a swivel connection 12 with an outlet pipe 13.

.A suitable pulley 14 is secured to the pipe 10 and is adapted to be driven by a belt 15 from a suitable motor (not shown).

Also rigidly carried by the container 4 surrounding and spaced from the pipe 6 is a standpipe 16. This is of such It will be seen that the four tubes of each set are disposed at 90 to each other and lie in the same plane. When the unit is rotated at high speed, jets of liquid are driven by centrifugal force from the tubes of each set and impinge so rapidly against the cylindrical bafile as to create, in effect, a continuous layer or sheet of liquid, which then flows downwardly along the baffie, and is discharged from the lower edge thereof.

Each of the tubes 17, instead of being round, is preferably of flattened cross section, as shown in FIG. 3, This results in more uniform heating of the liquid being treated, as hereinafter described.

Surrounding the rotary unit above described is a fixed,

vertical cylindrical baffle 18, of a height approximately equal to that of the cylindrical container 4. This baffle plate is spaced from and supported on the walls of the evaporating chamber by suitable anchoring rings 19 which are preferably of insulating material.

The liquid to be treated is introduced into the apparatus through pipe 20. It is delivered from this pipe into an electrode structure 21 which may be similar to that shown .in detail in my aforesaid prior patent. The electrode structure 21 is supplied with high frequency electrical energy from a generator 22, as in my said prior patent. From this electrode structure the liquid is delivered through pipe 23 into the upper end of the standpipe 16, filling the annular space within this standpipe. At the same time, a suitable heating medium, such as hot or warm water, or steam, is introduced by way of pipe 8 into the upper end of pipe 6 so that it fills the entire container 4 and surrounds all of the tubes 17. The heating medium escapes from the lower end of the container through pipes 10 and 13.

As above stated, the container, carrying the tubes 17, is rotated about a vertical axis by means of the pulley 14 and belt 15, with the result that the liquid being treated is driven radially outward through the tubes 17 by centrifugal force. The liquid issuing from the outer ends of the tubes impinge upon the bafile 18 and flows down-. wardly along the sloping bottom 2 of the evaporating chamber to the lower end thereof Where it flows out through pipe 24 into a suitable pump 23. p

This pump 23 delivers the liquid up through pipe 25 to and through an electrode structure 28 and thence through pipe 29 into the upper end of standpipe 16. The electrode structure 28 is connected to a high frequenecy generator 30 by means of conductors 31 and 33, the conductor 31 being connected with the central electrode 32, as in my said prior patent.

The finished product is drawn off through pipe 26 connected with the pipe 25 through a suitable valve 27.

Referring now to FIG. 4, it will be seen that this is closely similar to FIG. 1 and I have used the same reference characters to designate similar parts. It therefore seems unnecessary to describe these parts again in detail. The fundamental distinction between FIGS. 1 and 4 is the fact that, in FIG. 4, I have omitted electrode structures 21 and 28 which appear in FIG. 1, and in place thereof have provided special novel means for subjecting the liquid being treated to high frequency electrical energy inside of the evaporating chamber.

This novel means comprises a conductor 34 which passes through a block 35- of insulating material interposed between the wall of the evaporating chamber and the baffle plate 18. As more clearly shown in FIG. 5, this conductor 34 passes through the baffle 18 and is Welded to the inside thereof as at 37. The end of the conductor 34 is threaded and a nut 36 is screwed on it so as to clamp the block of insulating material 35 in position. The wall 1 of the evaporating chamber is formed with a relatively large opening 1a in which the conductor 34 and nut 36 are located, while the block 35 has a flange 38 secured by bolts 39 passing through the wall 1. A high frequency generator 40 has one side 41 connected to the conductor 34 and the other side 42 connected to ground as, for example, by means of one of the bolts 39.

In FIG. 1 it is immaterial whether or not the supporting rings 19 are formed of insulating material, and in fact in FIG. 1 the baffle 18 may be omitted altogether so that the jets discharged from the tubes 17 impinge directly upon and flow downwardly along the walls 1 of the evaporating chamber.

In FIG. 4, however, it is essential that the cylindrical baffie 18 be used and that the supporting rings 19 be formed of suitable insulating material such as that, for example, sold under the name Teflon.

Referring again to FIG. 4, it will be seen that as the tubes 17 rotate and the liquid is discharged from the outer ends thereof in the form of jets, these jets impinge upon the highly charged insulated bafile 18 so that the electrical energy traverses the liquid while it is in the form of jets between the ends of the tubes 17 and the baflle 18. So far as I am aware, it is a broadly new idea to cause a jet to impinge from a tube against a plate, either the tube or the plate being at ground potential and the other being highly charged, so that the electrical energy acts upon the liquid in the form of a jet at a point between the tube and the plate.

In both FIGS. 1 and 4, it will be seen that the liquid being treated is driven outwardly through the radial tubes 17 by centrifugal force and that, therefore, the clogging of these tubes by the building up of a film therein is substantially prevented. Also, by making the tubes of fiattened cross section, as shown in FIG. 3, they are relatively thin and the heat from the surrounding medium is transmitted to the liquid being treated more uniformly. For heat sensitive materials such as fruit juices, the heating medium is preferably warm or hot water, while in other applications it may be steam.

If, in either FIG. 1 or FIG. 4, it is desired to supply additional heat to the liquid, this may be done by means of what is known as a swept surface heater made by Cherry-Burrell Corporation and sold under the trade name Thermutator. This is shown diagrammatically in FIG. 6 at 43. It includes rotary scraper blades driven by a suitable motor 46 so that the liquid being treated cannot adhere to the walls of the heating chamber. The heating medium is supplied through pipes 44 and 45. As already mentioned, such a heater can be inserted either in the pipe 25 of FIG. 1 or the pipe 29 of FIG. 4.

In FIG. 7, I have illustrated more or less diagrammatically my improved means for presenting the transmission of heat from the conductor leading from the high frequency generator to the conductor which is fastened to the electrode. In this figure, the electrode casing is indicated at 28 and the high frequency generator at 30, as in FIG. 1. The conductor 31 extending from the high frequency generator to the electrode is formed in two sections 31a and 31 b disposed in end-to-end relation with an air gap 310 between them. These sections may be made either of rod or tubing. The section 3115, as in my said prior patent, is shown as being flattened and perforated and fitted over the threaded projecting end 32 of the central electrode to which it is clamped by means of a nut 32a. I have found that the electrical energy traverses the gap 310 effectively while this gap substantially prevents the transmission of heat from the section 31a to the section 31b. While the electrical energy will effectively transverse the gap 310 formed merely between the abuttting ends of the conductor sections, the transmission of the electrical energy across this gap may be increased by providing a pair of parallel plates 31d adjacent the gap as shown, these plates acting in the manner of a condenser.

What I claim is:

1. Apparatus for treating liqhids comprising an evaporating chamber, a unit disposed within said chamber and including a container rotatable about a vertical axis, a standpipe at the center of and rigid with said container and having an open upper end, a plurality of radially disposed open tubes communicating at their inner ends with said standpipe and projecting at their outer ends through the side wall of said container, means for feeding the liquid to be treated into the upper end of said standpipe whereby it enters said tubes, means for causing a heating medium to circulate through said container so as to surround and heat said tubes, means for rotating said container and tubes, so as to cause the liquid being treated to be driven by centrifugal force from said standpipe out through said heated tubes and discharged from the outer ends thereof into said chamber, and means for maintaining said chamber under high vacuum, whereby the volatile components of the heated liquid flash into vapor and are drawn off.

2. Apparatus in accordance with claim 1 in which the open tubes are of flattened cross section, so that all parts of the liquid are more uniformly heated.

3. Apparatus in accordance with claim 1 in which means are provided for subjecting the liquid discharged from said tubes inside of said chamber to the action of high frequency electrical energy.

4. Apparatus in accordance with claim 1 in which the means for feeding the liquid to be treated into said standpipe is a conduit through which the liquid flows in a confined stream, and in which means are provided for subjecting the liquid while so flowing to the action of high frequency electrical energy' 5. Apparatus in accordance with claim 1 in which a fixed, open ended cylindrical bathe surrounds said rotating container and tubes, so that the heated liquid discharged from the outer ends of said tubes impinges against said battle and flows from the bottom edge thereof into the lower part of said chamber.

6. Apparatus in accordance with claim 1 in which a fixed, open ended cylindrical baffle, spaced and insulated from the walls of said chamber, closely surrounds said rotating container and tubes, so that the liquid, discharged from the outer ends of said tubes impinges against said baffle, and a generator of high frequency electrical energy having one pole insulated from said chamber and electrically connected with said bafile, and the other pole grounded.

7. Apparatus in accordance with claim 1 in which means are provided for withdrawing the liquid from the bottom of said chamber and delivering it into the top of said standpipe, whereby the liquid is recycled through the apparatus.

8. Apparatus in accordance with claim 7 in which the means for feeding the liquid to be treated, and the means for delivering the liquid being recycled, into the top of said standpipe is, in each case, a conduit through which the liquid flows in a confined stream, and in which means are provided for subjecting both the liquid being fed in and the liquid being recycled, while so flowing in their respective conduits, to the action of high frequency electrical energy.

9. Apparatus for applying high frequency electrical energy to liquid materials, including an electrode in contact with such materials and a conductor connecting said electrode with a high frequency generator, said conductor comprising two sections disposed endto-end but separated by a clear, empty air gap, thus constituting a condenser whereby the electrical energy is transmitted from one section to another, but the transfer of heat from one section to the other is substantially prevented by said gap.

10. Apparatus for treating liquids comprising a heatexchanger unit including a container rotatable about a vertical axis, a standpipe at the center of and rigid with said container and having an open upper end, a plurality of substantially rectilinear radially disposed open tubes communicating at their inner ends with said standpipe and projecting at their outer ends through the side wall of said container, means for feeding the liquid to be treated into the upper end of said standpipe, whereby it enters said tubes, means for causing a fluid heat-exchange medium to circulate through said container so as to completely surround all parts of said tubes within said container, means for rotating said container and tubes so as to cause the liquid being treated to be driven by cen trifugal force from said standpipe out through said tubes and discharged from the outer ends thereof, and means for collecting the treated liquid thus discharged.

11. Apparatus in accordance with claim 10 in which a fixed, vertical, cylindrical baflle having an open lower end surrounds said rotating container and tubes, so that the treated liquid discharged from the outer ends of said tubes impinges against said baffle and flows downwardly toward and then from the bottom edge thereof.

12. Apparatus in accordance with claim 10 in which the tubes lie in the same plane and are arranged at an angle to each other, and in which a fixed, insulated, cylindrical, vertical baflle having an open lower end, surrounds said rotating container and tubes, so that the liquid, discharged from the outer end of said tubes, impinges against said battle to create a substantially continuous layer of liquid within the same, which layer then fiows downwardly from the bottom edge of said baffle, and a generator of high frequency electrical energy having one pole connected with said bafile and the other pole grounded on said container.

References Cited by the Examiner UNITED STATES PATENTS 1,932,405 10/33 Harris. 2,192,089 2/40 Long 1596 2,306,265 12/ 42 Heald. 2,483,623 10/49 Clayton 219-1065 2,493,073 1/50 Kineen. 2,551,360 5/51 Bierwirth 1596 X 2,996,439 8/61 Glover 1596 3,060,297 10/62 Sargeant. 3,072,490 l/ 63 Sargeant. 3,092,180 6/63 Dahlgreen l596 X FOREIGN PATENTS 504,048 4/39 Great Britain. 917,259 1/ 63 Great Britain.

NORMAN YUDKOFF, Primary Examiner.

Claims (1)

1. APPARATUS FOR TREATING LIQHIDS COMPRISING AN EVAPORATING CHAMBER, A UNIT DISPOSED WITHIN SAID CHAMBER AND INCLUDING A CONTAINER ROTATABLE ABOUT A VERTICAL AXIS, A STANDPIPE AT THE CENTER OF AND RIGID WITH SAID CONTAINER AND HAVING AN OPEN UPPER END, A PLURALITY OF RADIALLY DISPOSED OPEN TUBES COMMUNICATING AT THEIR INNER ENDS WITH SAID STANDPIPE AND PROJECTING AT THEIR OUTER ENDS THROUGH THE SIDE WAL,L OF SAID CONTAINER, MEANS FOR FEEDING THE LIQUID TO BE TREATED INTO THE UPPER END OF SAID STANDPIPE WHEREBY IT ENTERS SAID TUBES, MEANS FOR CAUSING A HEATING MEDIUM TO CIRCULATE THROUGH SAID CONTAINER SO AS TO SURROUND AND HEAT SAID TUBES, MEANS FOR ROTATING SAID CONTAINER AND TUBES, SO AS TO CAUSE THE LIQUID BEING TREATED TO BE DRIVEN BY CENTRIFUGAL FORCE FROM SAID STANDPIPE OUT THROUGH SAID HEATED TUBES AND DISCHARGED FROM THE OUTER ENDS THEREOF INTO SAID CHAMBER, AND MEANS FOR MAINTAINING SAID CHAMBER UNDER HIGH VACUUM, WHEREBY THE VOLATILE COMPONENTS OF THE HEATED LIQUID FLASH INTO VAPOR AND ARE DRAWN OFF.

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