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US2175995A - Method of centrifuging sugar - Google Patents

Method of centrifuging sugar Download PDF

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Publication number
US2175995A
US2175995A US113542A US11354236A US2175995A US 2175995 A US2175995 A US 2175995A US 113542 A US113542 A US 113542A US 11354236 A US11354236 A US 11354236A US 2175995 A US2175995 A US 2175995A
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US
United States
Prior art keywords
sugar
syrup
centrifugal
speed
crystals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US113542A
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English (en)
Inventor
Roberts Eugene
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Western States Machine Co
Original Assignee
Western States Machine Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Western States Machine Co filed Critical Western States Machine Co
Priority to US113542A priority Critical patent/US2175995A/en
Priority to FR830147D priority patent/FR830147A/fr
Application granted granted Critical
Publication of US2175995A publication Critical patent/US2175995A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C13—SUGAR INDUSTRY
    • C13B—PRODUCTION OF SUCROSE; APPARATUS SPECIALLY ADAPTED THEREFOR
    • C13B30/00—Crystallisation; Crystallising apparatus; Separating crystals from mother liquors ; Evaporating or boiling sugar juice
    • C13B30/04—Separating crystals from mother liquor
    • C13B30/06—Separating crystals from mother liquor by centrifugal force
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B11/00—Feeding, charging, or discharging bowls
    • B04B11/04—Periodical feeding or discharging; Control arrangements therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B15/00—Other accessories for centrifuges
    • B04B15/12—Other accessories for centrifuges for drying or washing the separated solid particles
    • C—CHEMISTRY; METALLURGY
    • C13—SUGAR INDUSTRY
    • C13B—PRODUCTION OF SUCROSE; APPARATUS SPECIALLY ADAPTED THEREFOR
    • C13B30/00—Crystallisation; Crystallising apparatus; Separating crystals from mother liquors ; Evaporating or boiling sugar juice
    • C13B30/04—Separating crystals from mother liquor
    • C13B30/08—Washing residual mother liquor from crystals
    • C13B30/10—Washing residual mother liquor from crystals in centrifuges

Definitions

  • This invention relates to improved methods of separating sugar crystals from syrup by centrifuging mixtures of these materials, which may be massecuites of any grade encountered in the man-A ufacture of sugar or magmas comprising mixtures formed by the addition of syrup to preformed crystals.
  • centrifugals generally used heretofore have been driven by belts or by motors directly connected to the spindles upon which the centrifugal baskets are mounted, and speeds of around 900 to 1,200 revolutions a minute have'been considered quite satisfactory for most purposes.
  • vobjects of my invention are to provide an improved vmethod of centrifuging sugar which enables the recovery of substantially greater amounts of sugar crystals kfrom a given quantity o f material forming a single charge, to
  • This eilcient syrup elimination when combined with control over the consistency of successive charges of the material introduced into the centrifugals, in ac- -cor'dance with preferred embodiments of the invention, permits maximum benefits of massecuite boiling and conditioning operations to be realized.
  • it When coupled with the cycle control and washing practices which are features of further embodiments of the invention, it enables the final cleansing of sugar crystals in centrifugals to be accomplished with maximum yield and quality of product, and enables other plant operations that are affected by the qualities of the sugar crystals and run-offs produced from the centrifugals to be improved in important respects.
  • centrifugal apparatus of the ltering type which is capable of rapid acceleration and high speed operation may be employed in carrying out the invention.
  • An especially suitable form of apparatus is illustrated in my copending application, Serial No. 124,244, filed Feb. 5, 1937, for Centrifugal apparatus.
  • filtering centrifugals'in which the centrifugal basket is of the standard perforated type having a diameter of 40 inches. It is to be understood, however, that the invention is not limited to the use of a basket of this size, since the principles of the invention apply to baskets of various sizes, with corresponding variations in the speeds of revolution.
  • the invention is described as it is applied specifically to the treatment of white massecuites and low grade massecuities. It produces unproved results, however,
  • the general practice is to flow the massecuite from a mixing chamber into the centrifugals in successive quantities, the sugar crystals being separated from the motor liquor in the centrifugals and the crystals being washed and nally discharged for subsequent treatment preliminary to packaging.
  • the present invention results in substantial improvements when applied to massecuites introduced into the centrifugals without reheating after leaving the vacuum pan, the better procedure is to reheat or maintain successive charges of the massecuite at a substantially uniform temperature between about and 195 F., and preferably between and 190 F., immediately before introduction into the centrifugals.
  • the charging of the centrifugals may take place before the basket has reached a substantial speed, or up to speeds of about 600 R. P.
  • M. may be completed at substantially the same speed, before the acceleration stage of the centrifuging cycle is started. I prefer, however, to begin charging the basket after it has reached a speed of approximately 300 R. P. M. and to carry out the charging operation during the acceleration of the basket, between about 300 and 500 R. P. M.
  • the speeds actually employed in either practice depend on the fluidity of the massecuite and the size of the sugar grain, which will vary with different grades of massecuites and different temperatures. For coarse grain sugars the speed of the basket during charging must be kept at a. low point to avoid unevenness in the sugar wall so as to maintain a smoothly running, perfectly balanced basket, while for sugars of finer grain 'dissolving of the crystals themselves.
  • aimee@ higher speeds within the range specified above are preferably employed, with acceleration during loading.
  • the loaded basket, or the basket to which the charge is being added during acceleration is accelerated from such speed to a speed in excess of 1250 R. P.M. in less than 40 seconds, and theI acceleration is preferably continued to a speed of not less than 1500 R. P. M. in less than one minute. In actual practice I find that acceleration to 1500 R. P. M.
  • I employ Wash water at a temperature of from about to 195 F. and preferably at a temperature of about to 190 F.
  • This water is sprayed onto the sugar from nozzles maintained under a pressure of about 25 to 35 pounds per square inch.
  • There results a mist-like spray of hot water which is heated sufliciently to remove quickly the molasses lm from the sugar and which strikes the sugar in a manner to penetrate the mass uniformly and to effect complete removal of the syrup.
  • unheated water is employedfor washing it has a chilling effect which tends to congeal the mother liquor on the crystals, resulting in poor filtration and incomplete purging of the crystals unless larger quantities of Wash water are used.
  • the figure graphically illustrates the advantages of my improved method over standard prior practice, in the treatment of white massecuite.
  • the abscissa represent elapsed time in the centrifuging cycles.
  • the ordinates represent the percent of available green liquor thrown olf the sugar crystals.
  • Curve A shows the operation of a standard centrifugal equipped with a directly connected motor and capable of reaching a speed of 1100 R. P. M. in two minutes.
  • Curve B represents the operation of a centrifugal used in carrying out the present invention and capable of reaching a speed of more than 1500 R.. P. M. with acceleration to 1500 R. P. M. in 40 seconds.
  • the wash water was turned on after forty seconds of operation, at the point indicated at la on the curve A, and the wash water was turned off at the point indicated at 2a on this curve.
  • Less than 55% of the'green liquor had been eliminated when the wash water was turned on according to this practice, and less than 75% had been eliminated when the Water was turned off.
  • curve B the improved method involving acceleration to more than 1250 R. P. M. in less than 40 seconds results in a flashing off of the green liquor such that more than 85% has been eliminated in less than 40 seconds.
  • the wash water is turned on, after 40 seconds as indicated at lb, the sugar has already been purged of considerably over 90% of the available green liquor, and over 95% of available green liquor has been eliminated when the wash water is turned off, as at 2b.
  • the above data relate to massecuites of extra fine grain.
  • the invention easily produces products of less than 1% moisture content, and the amount of wash water required for perfect purging is reduced to as low as seven quarts.
  • the present invention effects provements in the capacity of the centrifugals and the purity of the raw sugar obtained after separation of the mother liquor.
  • the centrifugal is brought to a speed of ⁇ at least 1250 R. P. M. in 40 seconds and to a speed of 1500 R. P. M. or higher in less than one minute.
  • 'I'he low grade massecuite is preferably heated to a temperature between about 95 F. and 130 F.
  • the rapid acceleration imparted to the massecuite according to this invention quickly throws the syrup from the crystals in a manner to obtain optimum purging, and a product of high' purity is obtained in a relatively short operating cycle.
  • the centrifuging of low grade massecuites generally does not involve washing of the sugar in the basket nor separation of wash syrup from green liquor.
  • the following table includes comparative data on the treatment of reheated low grade massecuites, taken from common sources of supply.
  • Test #2 96. 3 58. 1 10 127 97. 3 85. 0 87. 4 38. 1 10 122 98. 1 89. 9 91'. 8 35. 9 20 127 98.0 89. 0 90. 8 20 122 98. 4 90. 5 92.0
  • the invention is applicable to the centrifuging of afnations or raw sugar magmas in much the same manner as it applies to white massecuites, with correspondingly improved results. Similarly, it provides important advantages in the treatment of any type of sugar-syrup mixture. Essentially, the method of the invention, involving rapid acceleration to high speed, produces a maximum filtration, or maximum elimination of syrup.
  • the practical'accomplishments include:
  • the sugar when using the invention for 'the production of consumption sugar, is dried to the lowest possible moisture content at which it can be safely discharged from the centrifugals. This reduces the cost of drying, allows maximum granulator capacity and produces sugar of better luster. It also reduces the amount of "screenings through easier and faster drying and formation of less "hard lumps, thereby further increasing direct yields through reduction in material requiring remelting.
  • the improved method relates to any mixture of sugar crystals and syrup, whether termed technically a massecuite" or a magma". Furthermore, it is not restricted to specific types of apparatus, nor specic tem-v peratures for the material undergoing treatment, nor specic speeds of operation or cycles of operation, except as required by the claims appended hereto.
  • Nb is the speed of a basket Whose radius, in feet, is Vb
  • N is the given speed for a 40 inch basket.
  • the constant 1.667 is the radius, in feet, of the 40 inch basket.
  • the method of centrifuging mixtures consisting of grain sugar suspended in syrup which comprises introducing a charge of the mixture into a centrifugal and accelerating the centrifugal to a speed in excess of ⁇ 1250 R. P. M. within forty seconds.
  • the method of centrifuging mixtures consisting of grain sugar suspended in syrup which comprises introducing successive charges of the mixture into a centrifugal while maintained at a substantially uniform temperature between 150 to.195 F. and bringing the centrifugal in each instance to a speed in excess of 1250 R. P. M. in less than forty seconds.
  • the method of centrifuging mixtures consisting of grain sugar suspended in syrup which comprises introducing a charge of the mixture into a centrifugal during acceleration of the centrifugal between 300 and 600 R. P. M. and completing acceleration of the centrifugal to a speed in excess of 1250 R. P. M. Within 40 seconds from the beginning of the charging operation.
  • the method of centrifuging mixtures consisting of grain sugar suspended in syrup which comprises introducing a charge of the mixture into a centrifugal during acceleration of the centrifugal between 300 and 600 R. P. M., completing acceleration of the centrifugal to a speed in excess of 1250 R. P. M. in less than 40 seconds from the beginning ofthe charging operation and applying a spray of hot water to the material in thecentrifugal after a speed of 1250 R. P. M. has been reached.
  • the method of centrifuging mixtures consisting of grain sugar suspended in syrup which comprises introducing a charge of the mixture into a. centrifugal and accelerating the centrifugal to a speed in excess of 1500 R. P. M. in less than 1 minute.
  • the method of separating the constituents of mixtures consisting of grain sugar and adhering syrup which comprises introducing a charge of the mixture into a centrifugal, accelerating the centrifugal to a speed in excess of 1250 R. P. M. in less than 40 seconds, and applying a spray of washing liquid to the material in the centrifugal after a speed of 1250 R. P. M. has been reached.
  • a method of separating the constituentsof mixtures consisting of grain sugar and adhering syrup which comprises introducing successive trifugal, accelerating the centrifugal in each instance to a ,speed in excess of 1250 R. P. M. Within 40 seconds and applying tothe material in the centrifugal after a speed of 1250 R. P. M. has been reached a spray of water at a nozzle temperature in excess of 170, F. and a nozzle pressure of from 25 to 35 pounds per square inch.
  • the method of centrifuging free-purging sugar massecuites which comprises introducing successive charges of the massecuite or magmas maintained at a substantially uniform temperature between 170 and 195 F. into a centrifugal and expelling more than of the mother liquor from each charge before Washing the sugar by accelerating the centrifugal to a speed in ex-V cess of 1250 R. P. M. within 40 seconds.
  • the method of centrifuging free-purging sugar massecuites which ,comprises introducing successive charges of the massecuite or magmas maintained at a substantially uniform temperature between 170 and 195 F. into a centrifugal, expelling more than 85% of the mother liquor from each charge before washing the sugar by accelerating the centrifugal to a speed in excess of 1250 R. P. M. within 40 seconds and applying to the material in the centrifugal after more than 85% of the mother liquor has been expelled a mist-like yspray of water at a nozzle temperature in excess of 170 F.
  • the method of centrifuging mixtures of grain sugar and syrup and of producing sugar crystals of high quality and wash syrup of high purity in comparison with the syrup purged from the sugar which comprises charging a batch of the mixture into a centrifugal revolving at loading speed, purging more than 85% of the syrup from the batch before washing the sugar by accelerating the centrifugal from loading speed to a speed in excess of 1250 R. P. M. within 40 seconds, and applying a spray of water to the material in the centrifugal after more than 85% of the syrup has been purged therefrom.
  • the method of centrifuging mixtures of grain sugar 'and syrup and of producing sugar crystals of high quality and wash syrup of high purity in comparison with the syrup purged from the sugar which comprises charging successive batches of the mixture maintained at a substantially uniform temperature and fluidity into a centrifugal revolving at loading speed, purging more than of the. syrup from the batch in each instance before washing the sugar by acceleratlng the centrifugal from loading speed to a speed of at least 1500 R. P. M. in less than 1' minute, and applying a spray of hot Water to the material in the centrifugal after more than 90% of the syrup has been purged therefrom.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Organic Chemistry (AREA)
  • Confectionery (AREA)
US113542A 1936-12-01 1936-12-01 Method of centrifuging sugar Expired - Lifetime US2175995A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US113542A US2175995A (en) 1936-12-01 1936-12-01 Method of centrifuging sugar
FR830147D FR830147A (fr) 1936-12-01 1937-11-29 Perfectionnements aux procédés de turbinage des mélanges sucrés

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US113542A US2175995A (en) 1936-12-01 1936-12-01 Method of centrifuging sugar

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2626055A (en) * 1948-12-14 1953-01-20 Castle & Cooke Ltd Apparatus for treating molasses

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2626055A (en) * 1948-12-14 1953-01-20 Castle & Cooke Ltd Apparatus for treating molasses

Also Published As

Publication number Publication date
FR830147A (fr) 1938-07-21

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