US3660043A - Method and device for feeding crystals and melts - Google Patents

Method and device for feeding crystals and melts Download PDF

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Publication number
US3660043A
US3660043A US796321*A US3660043DA US3660043A US 3660043 A US3660043 A US 3660043A US 3660043D A US3660043D A US 3660043DA US 3660043 A US3660043 A US 3660043A
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Prior art keywords
strip
column
crystals
melts
feeding
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Expired - Lifetime
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US796321*A
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English (en)
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Herman Schildknecht
Klaus Maas
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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
    • B01D9/004—Fractional crystallisation; Fractionating or rectifying columns
    • 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 present invention is directed to apparatus for feeding crystals and melts in a crystallization column and is more specifically directed to an improvement in the impeller used for this purpose.
  • the counter-current of the crystals and melt in this apparatus is carried out by means of a spiral.
  • This comprises a coil spring (preferably of steel wire) with square or lenticular cross section which rotates in the annular space between concentric stationary tubes.
  • These tubes are commonly made of glass but, of course, any other suitable material inert to their contents may be used.
  • the spiral. strip described herein takes the place of the prior art feed spiral. By using this device no center portion of the column is required and thus the construction of the overall apparatus is simplified. Moreover, this potential source of heat dissipation problems is eliminated.
  • the twisted strip as described and claimed herein is much more rigid than the comparable feed spirals and therefore permits much longer columns. On the other hand for short columns lower strength material such as glass may be used. Obviously glass is substantially inert to almost all crystallization materials and would be desirable particularly where high corrosion is an important object.
  • the present invention will permit the use of glass because of the increased strength provided by the form in which the strip is inserted.
  • Such a strip can be prepared using a width as small as approximately 1 mm and its minimum thickness is then about 0.2 mm.
  • the strip can, of course, comprise any material which is inert to the substances being handled and which is stable at working temperatures.
  • glass stainless steel is particularly suitable for the manufacture of the spiral strips of this invention.
  • a piece of steel plate can be cut into strips of the desired width and each strip twisted into a suitable spiral.
  • the strips are encased in a protective coat of an inert material such as teflon.
  • an inert material such as teflon.
  • This material is easily applied to thestrips as the strips do not come in contact during manufacture either with a guide or a core of any kind.
  • a very simple method of coating with teflon can be carried out by pushing unsintered teflon hose over the steel band which is then twisted in the usual manner. The entire completed feeding means is then sintered and the hose fuses to the metal.
  • the end opposite that connected to the driving means has one to two turns which are directed oppositely to the other turns.
  • An extended untwisted flat portion of the strip is disposed between the turns of the spiral and the counterturns on the end opposite that connected to the driving means. These counterturns form a crystal stopper during the column crystallization at the point at which the reversal takes place. This has a favorable effect on the separating process. Moreover, this helps to prevent lifting of the feeding device by the crystals accumulated at the bottom of the column.
  • FIG. 1 is a spiral strip of the present invention.
  • FIG. 2 is a view partly in section showing the strip of H6. 1
  • a driving rod 1 affixed to one end of the spiral strip.
  • the strip has twists 2 and counterturns 3.
  • the strip is hollow and its interior is provided with resistance wire 5 for generating of heat.
  • a simple way to manufacture such strips is the installation of a resistance wire 5 in a flat tube prior to turning.
  • the heated spiral strip often permits the feeding of material which has a tendency to agglomerate.
  • the apparatus may contain in addition to internal heating devices an external heater surrounding the column.
  • cooler 7 preferably adjacent the upper end of column 4.
  • the two heating devices can supply heat of different intensities to the material being handled. It has been found that the separating effect can be improved by this means. However, it is often costly in its use of power. It is, therefore, of primary value on the laboratory scale where these matters are of minor concern only.
  • EXAMPLE 2 The same procedure as set forth in Example 1 was followed except for the following variations: the inside diameter of the column was 2 mm and the steel strip had a usable length of 100 mm. Its cross section was 2 mm X 0.6 mm, and there were 25 half turns (twists) and 2 counterturns. The strip was rotated at 200 rpm and the separating time was 10 minutes. 200 mg of the mixed crystal substance were introduced and substantially the same results were obtained as with Example 1.
  • EXAMPLE 3 In this Example a crystallization column with an inside diameter of 7 mm was used. A strip of stainless steel having a usable length of 1,000 mm, a cross section of 7 mm X 1 mm, 80 twists and 2 countertums was rotated in the column at a speed of 100 rpm. The charge was 30 g of technical grade caprolactam (also known as extract lactam) as a eutectic forming substance and the material is crystallized. After a separating time of 60 minutes [5 cm dark brown impurity concentrate is found at one end of the column. Next to it is 10 cm of brown to light brown transition material and there are 75 cm of pure white caprolactam. This separation is satisfactory for practical use.
  • technical grade caprolactam also known as extract lactam
  • EXAMPLE 4 This separation was carried out in a manner similar to that of Example 3 but with the following differences: The inside diameter of the column was 25 mm and it contained a strip having a useful length of 1,500 mm, a cross section of 25 X 8 mm and there was 35 twists and l countertum. The strip was rotated at 50 rpm for 60 minutes. The charge was 400 g of the same material as used in the Example 3.
  • EXAMPLE 5 In this Example a hollow strip containing an internal heating device was used. The current was supplied by sliding contacts and the width of the flat tubes which were compressed from suitable for column ciglsitallization of substances which crystallize only with great d' culty. It appears that the temperature gradient obtainable between the feeding device and the column wall aids in the crystallization process.
  • a vertical crystallization column apparatus for separating crystals and melt into higher and lower melting fractions comprising: a rigid strip having edges, said strip being freely rotatably mounted in said column, said strip having an upper and bottom section having twists thereon, the twists of one section being directed oppositely to that of the other portion of said rigid strip and an extended untwisted flat portion forming the junction between the twists of the upper section and the twists of the bottom section, such that said higher melting fraction is urged by said upper section toward the untwisted .flat portion whereby said untwisted flat portion facilitates separation.
  • An apparatus for feeding crystals and melts in a crystallization column comprising a rigid strip having edges freely rotatably mounted in said column, said strip twisted spirally in one direction about its longitudinal axis, said strip being connected to a driving means whereby said strip is adapted for rotation about said axis, said strip being a flattened tube, and said heating device comprising a resistance wire in said tube connected to a source of electricity.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
US796321*A 1968-01-31 1969-01-31 Method and device for feeding crystals and melts Expired - Lifetime US3660043A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DESC041915 1968-01-31
DE19681719468 DE1719468B1 (de) 1968-01-31 1968-01-31 Foerderschnecke zum Transport von Kristallen und Schmelze in einer Kristallisationskolonne

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US3660043A true US3660043A (en) 1972-05-02

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US (1) US3660043A (de)
CH (1) CH502833A (de)
DE (1) DE1719468B1 (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4340547A (en) * 1980-03-10 1982-07-20 Scm Corporation Process for concentrating a flow of lipids in solvent
US4453959A (en) * 1982-02-25 1984-06-12 Bishkin D Bruce Crystal washing and purification method
EP0119178A1 (de) * 1983-03-15 1984-09-19 Boliden Aktiebolag Verfahren zur Separierung von Lösungen
USD623319S1 (en) * 2008-04-24 2010-09-07 3Form, Inc. Architectural panel with flowing element
USD623320S1 (en) * 2008-04-24 2010-09-07 3Form, Inc. Architectural panel with valley element
US20120298340A1 (en) * 2011-05-25 2012-11-29 Al-Otaibi Abdullah M Turbulence-inducing devices for tubular heat exchangers

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2540706A (en) * 1947-05-22 1951-02-06 Texas Co Process and apparatus for effecting catalytic reactions
US2617273A (en) * 1949-04-25 1952-11-11 Phillips Petroleum Co Continuous crystallization apparatus and process
US2679539A (en) * 1949-12-22 1954-05-25 Phillips Petroleum Co Separation of eutectic-forming mixtures by crystallization
US2780663A (en) * 1953-05-29 1957-02-05 Standard Oil Co Fractional crystallization and crystal washing
US2800411A (en) * 1954-03-31 1957-07-23 Phillips Petroleum Co Crystal purification apparatus and process
US2818631A (en) * 1952-08-16 1958-01-07 Syntron Co Sheathed electric heating elements
US2920347A (en) * 1955-12-02 1960-01-12 Du Pont Sealing means for rotary pumps
DE1161852B (de) * 1956-11-03 1964-01-30 Goeppner Kaiserslautern Eisen Duennschichtverdampfer
US3457982A (en) * 1966-11-14 1969-07-29 Hugo H Sephton Evaporation and distillation apparatus
US3898271A (en) * 1971-06-08 1975-08-05 Squibb & Sons Inc Cyclopropylmethylphenylacetic acids and derivatives

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2540706A (en) * 1947-05-22 1951-02-06 Texas Co Process and apparatus for effecting catalytic reactions
US2617273A (en) * 1949-04-25 1952-11-11 Phillips Petroleum Co Continuous crystallization apparatus and process
US2679539A (en) * 1949-12-22 1954-05-25 Phillips Petroleum Co Separation of eutectic-forming mixtures by crystallization
US2818631A (en) * 1952-08-16 1958-01-07 Syntron Co Sheathed electric heating elements
US2780663A (en) * 1953-05-29 1957-02-05 Standard Oil Co Fractional crystallization and crystal washing
US2800411A (en) * 1954-03-31 1957-07-23 Phillips Petroleum Co Crystal purification apparatus and process
US2920347A (en) * 1955-12-02 1960-01-12 Du Pont Sealing means for rotary pumps
DE1161852B (de) * 1956-11-03 1964-01-30 Goeppner Kaiserslautern Eisen Duennschichtverdampfer
US3457982A (en) * 1966-11-14 1969-07-29 Hugo H Sephton Evaporation and distillation apparatus
US3898271A (en) * 1971-06-08 1975-08-05 Squibb & Sons Inc Cyclopropylmethylphenylacetic acids and derivatives

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Betts et al., J. Applied Chem. 1968 Vol. 17 June pp. 180 182 *
Schildhnecht & Powers Chemiher-Zeitung/Chem. Apperatur, 1966 N. 15 pp. 135 140 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4340547A (en) * 1980-03-10 1982-07-20 Scm Corporation Process for concentrating a flow of lipids in solvent
US4453959A (en) * 1982-02-25 1984-06-12 Bishkin D Bruce Crystal washing and purification method
EP0119178A1 (de) * 1983-03-15 1984-09-19 Boliden Aktiebolag Verfahren zur Separierung von Lösungen
USD623319S1 (en) * 2008-04-24 2010-09-07 3Form, Inc. Architectural panel with flowing element
USD623320S1 (en) * 2008-04-24 2010-09-07 3Form, Inc. Architectural panel with valley element
US20120298340A1 (en) * 2011-05-25 2012-11-29 Al-Otaibi Abdullah M Turbulence-inducing devices for tubular heat exchangers
US9605913B2 (en) * 2011-05-25 2017-03-28 Saudi Arabian Oil Company Turbulence-inducing devices for tubular heat exchangers

Also Published As

Publication number Publication date
CH502833A (de) 1971-02-15
DE1719468B1 (de) 1971-01-28

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