US2570612A - Method and apparatus for removing the crusts of the cooling elements of a continuously operating crystallizer - Google Patents

Method and apparatus for removing the crusts of the cooling elements of a continuously operating crystallizer Download PDF

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US2570612A
US2570612A US30394A US3039448A US2570612A US 2570612 A US2570612 A US 2570612A US 30394 A US30394 A US 30394A US 3039448 A US3039448 A US 3039448A US 2570612 A US2570612 A US 2570612A
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cooling elements
crusts
continuously operating
crystallizing
container
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US30394A
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Vahl Laszlo
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Werkspoor NV
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Werkspoor NV
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D9/00—Crystallisation
    • B01D9/0004—Crystallisation cooling by heat exchange
    • B01D9/0013—Crystallisation cooling by heat exchange by indirect heat exchange
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D9/00—Crystallisation
    • B01D9/005—Selection of auxiliary, e.g. for control of crystallisation nuclei, of crystal growth, of adherence to walls; Arrangements for introduction thereof

Definitions

  • the invention has for its object to remove the drawbacks of said known methods and to deal with the formation of crusts or scale on the cooling elements of continuously operating crystallizers in simple manner.
  • the crust is periodically molten by'heating means operating on the outer surface of the cooling elements in such a manner that the molten mass flows back into the crystallizing mass.
  • the crystals preferably should have a melting point less than 100 centigrade.
  • the heating means for melting the crusts on the discs may be formed as heated scrapers which are periodically brought to their operative position relative to the discs.
  • the heating means may also direct jets of hot air or steam on the.
  • the drawing illustrates an embodiment of a device according to the invention as applied to a crystallizing apparatus of the kind described in Patent 1,868,406.
  • Fig. 1 is a cross section of the crystallization trough and Fig. 2 shows a plan view of a cooling disc and the cooperating heating element formed as a scraper.
  • a rotary hollow shaft 2 is mounted on which sector-shaped cooling discs 3 are secured.
  • a heating element 4 is adapted to cooperate which from time to time is brought into its operative position shown in full lines in Fig. 1.
  • the element 4 which is formed as a scraper is hollow and is heated e. g. by an electric resistance 5 or by steam.
  • the element 4 is normally held in its inoperative position as shown in dotted lines in Fig. 1 and to this end the element l is secured to a shaft 6 in order to be swung by means of lever 1.
  • the heating elements may be actuated automatically or manually.
  • the element 4 Whenever the crusts on the cooling discs have grown too thick the element 4 is brought into its operative position and thus acts on the surface of the disc portion extending above the level of the crystallizing mass in order to melt the crusts thereon. During said operation the rotary speed of the discs is preferably reduced. The molten mass flows back into the trough.
  • the solution to be crystallized may be fed to the surface of the cooling elements whereby the melting and removing of the crusts is facilitated.
  • a continuously operable crystallization apparatus comprising a container for crystallizing liquid, a plurality of hollow disc-like cooling elements journalled in said container on a substantially horizontal axis for rotative movement through the liquid and with their upper portions above the normal level of the crystallizing mass, and a plurality of scraper members respectively cooperative with said cooling elements and mounted on said container adjacent the upper portions of said cooling elements and for movement between inoperative positions beyond said cooling elements and operative positions adjacent said upper portions of said cooling elements for removing crystallized crusts therefrom.
  • scraper members comprise arms pivotally mounted at one end to extend radially along the sides of said cooling elements when in operative position.
  • scraper members comprise heating means to supply heat from said scraper members to said cooling elements for melting at least a part of the crusts thereon.

Description

Oct. 9, 1951 L. vAHL 2,570,612
METHOD AND APPARATUS FOR REMOVING THE CRUSTS OF THE COOLING ELEMENTS OF A CONTINUOUSLY OPERATING CRYSTALLIZER Filed June 1, 1948 Patented Oct. 9, 1951.
METHOD AND- APPARATUS FOR REMOVING THE CRUSTS OF THE COOLING ELEMENTS OF A CONTINUOUSLY CRYS- TALLIZER Laszlo Vahl, Muiderberg, Netherlands, assignor to Werkspoor N. V., Amsterdam, Netherlands, a company of the Netherlands Application June 1, 1948, Serial No. 30,394 In the Netherlands June 5, 1947 4 Claims. (Cl. 23-273) When crystallizing solutions in continuously operating crystallization apparatus the difliculty arises that the crystals form crusts or scale on the surface of the cooling elements which have to be removed. For removing the crusts or scale usually scrapers are provided, scraping the crusts off the cooling surfaces, but with such scrapers the crusts are only incompletely removed and moreover such scrapers are liable to heavy wear particularly with hard crystals.
For removing crusts formed by crystals having a low melting point it has been proposed to melt the crusts periodically by passing hot water or steam instead of the cooling fluid through the cooling elements. Said method, however, has the drawback that the temperature conditions in the continuously operating apparatus are disturbed so that the cleaning of the cooling elements is accompanied by a serious interruption of the normal operation.
The invention has for its object to remove the drawbacks of said known methods and to deal with the formation of crusts or scale on the cooling elements of continuously operating crystallizers in simple manner. According to the invention the crust is periodically molten by'heating means operating on the outer surface of the cooling elements in such a manner that the molten mass flows back into the crystallizing mass. The crystals preferably should have a melting point less than 100 centigrade.
With a crystallizing apparatus comprising cooling elements consisting of a set of rotary hollow discs such as is described in Patent 1,868,406 the heating means for melting the crusts on the discs may be formed as heated scrapers which are periodically brought to their operative position relative to the discs. The heating means may also direct jets of hot air or steam on the.
cooling elements.
The drawing illustrates an embodiment of a device according to the invention as applied to a crystallizing apparatus of the kind described in Patent 1,868,406.
Fig. 1 is a cross section of the crystallization trough and Fig. 2 shows a plan view of a cooling disc and the cooperating heating element formed as a scraper.
In the trough I a rotary hollow shaft 2 is mounted on which sector-shaped cooling discs 3 are secured. With each of said discs 3 a heating element 4 is adapted to cooperate which from time to time is brought into its operative position shown in full lines in Fig. 1. The element 4 which is formed as a scraper is hollow and is heated e. g. by an electric resistance 5 or by steam. The element 4 is normally held in its inoperative position as shown in dotted lines in Fig. 1 and to this end the element l is secured to a shaft 6 in order to be swung by means of lever 1. The heating elements may be actuated automatically or manually.
Whenever the crusts on the cooling discs have grown too thick the element 4 is brought into its operative position and thus acts on the surface of the disc portion extending above the level of the crystallizing mass in order to melt the crusts thereon. During said operation the rotary speed of the discs is preferably reduced. The molten mass flows back into the trough.
Simultaneously with the melting of the crusts on the cooling elements by the heating means the solution to be crystallized may be fed to the surface of the cooling elements whereby the melting and removing of the crusts is facilitated.
What I claim is:
1. A continuously operable crystallization apparatus comprising a container for crystallizing liquid, a plurality of hollow disc-like cooling elements journalled in said container on a substantially horizontal axis for rotative movement through the liquid and with their upper portions above the normal level of the crystallizing mass, and a plurality of scraper members respectively cooperative with said cooling elements and mounted on said container adjacent the upper portions of said cooling elements and for movement between inoperative positions beyond said cooling elements and operative positions adjacent said upper portions of said cooling elements for removing crystallized crusts therefrom.
2. An apparatus as defined in claim 1 wherein said scraper members comprise arms pivotally mounted at one end to extend radially along the sides of said cooling elements when in operative position.
3. An apparatus as defined in claim 1 wherein said scraper members comprise heating means to supply heat from said scraper members to said cooling elements for melting at least a part of the crusts thereon.
4. In a method for removing the crusts from rotary cooling elements of a continuously operating crystallization apparatus for producing crystals having a melting point lower than (7., melting the crusts periodically by externally directing heat on that part of the cooling elements of said apparatus which is above the level of the crystallizing mass, simultaneously scraping the crusts from the cooling elements and returning Number the molten mass to the crystallizing mass. 1,755,059 LAszL VAHL. 1,790,544 1,868,406 REFERENCES CITED 5 2,255,393
The following references are of record in the file of this patent: Number UNITED STATES PATENTS 291,035
Number Name Date 10 1,430,900 Haferkamp Oct. 3, 1922 Name Date Gallagher Apr. 15, 1930 Hoover Jan. 27, 1931 Bonath July 19, 1932 Osborn Sept. 9, 1941 FOREIGN PATENTS Country Date Great Britain Apr. 4, 1929

Claims (1)

1. A CONTINUOUSLY OPERABLE CRYSTALLIZATION APPARATUS COMPRISING A CONTAINER FOR CRYSTALLIZING LIQUID, A PLURALITY OF HOLLOW DISC-LIKE COOLING ELEMENTS JOURNALLED IN SAID CONTAINER ON A SUBSTANTIALLY HORIZONTAL AXIS FOR ROTATIVE MOVEMENT THROUGH THE LIQUID AND WITH THEIR UPPER PORTIONS ABOVE THE NORMAL LEVEL OF THE CRYSTALLIZING MASS, AND A PLURALITY OF SCRAPER MEMBERS RESPECTIVELY COOPERATIVE WITH SAID COOLING ELEMENTS AND MOUNTED ON SAID CONTAINER ADJACENT THE UPPER PORTIONS OF SAID COOLING ELEMENTS AND FOR MOVEMENT BETWEEN INOPERATIVE POSITIONS BEYOND SAID COOLING ELEMENTS AND OPERATIVE POSITIONS ADJA-
US30394A 1947-06-05 1948-06-01 Method and apparatus for removing the crusts of the cooling elements of a continuously operating crystallizer Expired - Lifetime US2570612A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2701266A (en) * 1949-08-12 1955-02-01 Ici Ltd Separation of p-xylene by crystallization
US3908001A (en) * 1971-11-18 1975-09-23 Energy Dev Ass Manufacture of chlorine hydrate
US4486395A (en) * 1979-12-19 1984-12-04 Goudsche Machinefabriek B.V. Continuously working crystallizer

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1430900A (en) * 1920-10-28 1922-10-03 Diamond Match Co Apparatus for the production of crystals
GB291035A (en) * 1927-05-24 1929-04-04 Alois Rolz Improvements in cooling devices for mashing vessels for crystallisable material, more particularly for the sugar industry
US1755059A (en) * 1929-02-21 1930-04-15 Jr Edward J Gallagher Windshield wiper
US1790544A (en) * 1931-01-27 Automobile windshield scraper
US1868406A (en) * 1928-10-11 1932-07-19 Werkspoor Nv Apparatus for the heat treatment of sugar solutions either completely or partly crystallized
US2255393A (en) * 1940-03-28 1941-09-09 Osborn Charles Lee Windshield cleaner

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1790544A (en) * 1931-01-27 Automobile windshield scraper
US1430900A (en) * 1920-10-28 1922-10-03 Diamond Match Co Apparatus for the production of crystals
GB291035A (en) * 1927-05-24 1929-04-04 Alois Rolz Improvements in cooling devices for mashing vessels for crystallisable material, more particularly for the sugar industry
US1868406A (en) * 1928-10-11 1932-07-19 Werkspoor Nv Apparatus for the heat treatment of sugar solutions either completely or partly crystallized
US1755059A (en) * 1929-02-21 1930-04-15 Jr Edward J Gallagher Windshield wiper
US2255393A (en) * 1940-03-28 1941-09-09 Osborn Charles Lee Windshield cleaner

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2701266A (en) * 1949-08-12 1955-02-01 Ici Ltd Separation of p-xylene by crystallization
US3908001A (en) * 1971-11-18 1975-09-23 Energy Dev Ass Manufacture of chlorine hydrate
US4486395A (en) * 1979-12-19 1984-12-04 Goudsche Machinefabriek B.V. Continuously working crystallizer

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