Flocculants Used in Sugar Processing | Flocculant Dosing Calculation

Role of Flocculants in Sugar Industry | Flocculant Dosing Online Calculator

Introduction of flocculants:

Flocculants are a reagent added  to a dispersion of solids in a liquid to bring together  the fine particles to from floc.

The flocculants are generally classified as natural flocculants and Synthetic flocculants.

Role of Flocculants in Sugar Industry | Flocculant Dosing Online Calculator

Natural Flocculants:

They are water soluble anionic, cationic, non ionic polymers . Non ionic polymers adsorb on the suspended particles The most common natural flocculants are

  • Starch derivatives: Mostly pregelatinized hence water soluble . They are corn or potato, starch are natural starches, anionic oxides starches or amine treated cationic starches . They used of this classes of product has decreased in water treatment but remain important in the paper industries .
  • Polysaccharides: Usually guar ,gums & mostly used in acidic medium .
  • Alginate: Anionic & used in potable water treatment  

Synthetic flocculants: 

Polyacrylamides: The most common polymers are those based on Polyacrylamide.  Which is a a nonionic polymer. Their effect is due to bridging between particles polymer chains.  Polymer can be given anionic character by co polymerizing acrylmide with acryl amide acid,.  Cationic polymer are prepared by co polymerizing acryl amide with a cationic monomer.  All available acryl amide based polymers have a specific amount of ionic monomer giving a certain degree of ionic characters. 

Action of flocculants:

  • Dispersion of polymer in solution phase.
  • Transport of polymer to solid phase.
  • Adsorption of polymer on solid surface.
  • Collision of particles being adsorbed polymer to permit formation.

Advantages of flocculants in clarification:

  • Rate of settling is fast.
  • Batter  compactness  in  mud.
  • Improved  clarity  of  juice.
  • Reduction  in  color  formation  and  mud  volume.
  • Due  to  thickening  of  mud  lesser  sugar  loss  in  filter  cakes.
  • Efficiency  of  vacuum  filter  improve.
  • Clarifier  capacity  increased  by  10-20 %.
  • 0.3  to 0.5  rise  in  purity  achieved  from  mixed  juice  to  clear juice.
  • Reduction  in  filter  cake  pol  by  0.3 to 0.5 units.

Flocculents in sugar industry:       

  1. A number of synthetic flocculating agents are using in the sugar industry clarification process. These flocculants are synthetic high molecular weight polyacrylamides which are partially hydrolysed. Their efficiency as settling aids depends on the molecular weight which ranges between 7 to 10 million and the degree of hydrolysis.
  2. These compounds serve as bridges among particles of precipitate and thus bring about formation of bigger aggregates of flocs.
  3. The most common flocculants used for juice clarification as well as filter feed conditioning are hyolyzed polyacrylamide compounds, Which are anionic types. Cationic type of flocculents have much more limited use, mainly as decolorants in syrup flotation processes.
  4.  They are added as 0.05 % concentrated solution in water at the rate of 1.5 to 5 ppm on juice,
  5. The dosing to be connectec to the treated juice in the pipe connecting flash tank to clarifier.
  6. In the trayless clarifier has reduced the time of juice retention to 45 to 60 minutes. For improving settling rate and increasing the clarifier through put the addition of synthetic flocculant is essential.
  7. Thus the introduction of synthetic polyacrylamide as settling aids has been a significant advance in the process of clarification.

Flocculant Properties:

Property Effects
Molecular weight increase Poor solubility, more viscous solutions, chain more shear sensitive, Higher unit cost, Higher optimum dose, bridging favored, large flocs and faster settling but higher sediment volume
Temperature Change Complex effects
Dose increase Better flocculation up to optimum
Shear increase Breakdown of long chain, irreversible
Particle surface area increase Increase flocculants consumption, ultra fines, susceptible to over dosing and restabilisation.
Suspension pH Non ionic little affected, ionization and extension of anionic at alkaline pH- converse for catatonics, also alters particle charge, combined effects on flocculation are complex.
Suspension ionic strength Similar to suspension pH- can promote or inhibit flocculation, Excess salt lowers solubility, coils polymer
Polymer charge density increase Extends polymer solution under suitable conditions, decrease adsorption on to particle of same sign.

Role of Flocculants in Sugar Industry | Flocculant Dosing Online Calculator

Clarification in sugar process:

  1. The  clarification  step  in  sugar  manufacture  is  designed  to  remove  insoluble  suspended  impurities  from  the  mixed  juice .
  2. The formation of cane juice floc is based on Ca3(PO)4 and protein. Its effective density is varied by surface charge effects (Zeta potential).
  3. Flocculation has been described by Crees et al. as a two-stage reaction, the first step being the scavenging of individual particles into micro flocs, and the second being the agglomeration of these into macro-flocs that settle relatively rapidly.
  4. The nature of  colloid  particles  must  be  collected  into  agglomerates. The  intended effect  of  juice  clarification  by  sedimentation  is  to  achieve  1. higher   clarity  of  juice  2. compact  volume  of  mud. 
  5. The higher  clarity  of  juice  means  fewer  suspended  solids.  Flocculants  improve juice  clarity  by  decreasing  suspended   solids.  The  compactness  of  mud  can  reduce  the  retention  time  of  juice  inside  the  clarifier  thus  reducing  the  color  formation  and  also  sucrose  degradation.

Flocculant preparation and dosing:

  1. The flocculant tanks in either stainless steel or suitable MS tank with epoxy painting.  This eliminates the potential contact between flocculant molecules and iron, which can quickly result in degraded flocculant.
  2. The preparation tank should be located directly above the stock holding tank. The preparation tank having stirrer and its recommended speed of 10-15 rev/min. Otherwise air sparger is one of the best option for preparation of flocculent.
  3. Always ensure that in-line valves are fully open when dropping the solution from preparation tank to holding tank. Because molecules  will be sheared if the solution is passed through partially open valves.
  4. It having two tanks are sized to provide 4 to 8 hours supply of 0.05% to 0.2% concentration. The flocculant demand equivalent to 1.5 to 4 ppm on juice. The concentarion and dosing ppm may be veariy according to type of clarifier and dosing process. The final dosing solution concentarion to be maintain 0.05%.
  5. A minimum of four hours of preparation should be allowed before the flocculant solution is dropped to the holding tank. A mixing time of two hours should be considered as the absolute minimum mixing time and should only be adopted as an emergency procedure.
  6. The water supply must be of good quality with a pH greater than 8, of low hardness and be less than 50ºC. It is recommended that cooled condensate with 8 pH.
  7. It is essential that all the flocculant powder is wetted before reaching the water in the mixing tank to prevent the formation of large lumps or ‘oysters’ of flocculant, which are difficult to dissolve fully, and can block pipes and screens.
  8. Suitable disperser units consist of a funnel hopper and a variable aperture arrangement designed to ensure wetted individual particles of flocculant powder.
  9. Flocculant solution will become ineffective after 18 hours, so fresh solution must be prepared after a long process stoppage.
  10. The most suitable pump for flocculant is a progressing cavity pump operating at slow speeds with a variable frequency drive.
  11. In some designers flocculant preared by 0.2% concentration and the dilute to 0.03 to 0.05% solution by inline mixer with condensate water or clear juice while solution passing from flocculent pump to flash tank.  It will helpful to increase the useful life of the flocculant and reduce the water dilution.

Flocculant preparation and holding tank volume and dosing pump calculation.

In this we take one example and find the above parameters.

Flocculant Dosing for clarifier
S.No Description Sign Values UOM Remarks
1 Crushing rate TCH 210 TCH
2 Flocculant Dosing R 2 PPM
3 Concentration of flocculant C 0.05 % 0.05 to 0.2 %
4 Retention time T 4 hrs. 4 to 8 hrs.
1 Flocculant Quantity Q = TCH x R / 1000 0.42 Kg/hr
2 Flocculent flow rate Qr = Q x 100/ C 840 Lt/ hr
3 Pump capacity required Qr x 1.1 924 Lt/ hr 10% extra
4 Preparation tank capacity (Qr x T/1000) x 1.1 3.696 M3 10% extra
5 Holding or stock tank capacity (Qr x T/1000) x 1.2 4.032 M3 20% extra

Flocculant Dosing Online Calculator

Sugar Process Industry Terminology in Clarification section like Imbibition, Bagacillo,Bagasse,Cush Cush,Fiber,Lime,Flocculent,Affination,Raw Juice etc.

Phosphoric Acid(H3PO4) in sugar process industry and online calculator to find required dosing quantity in kgs and also find present going condition in PPM.

Juice Clarifier Flash Tank design parameters like dia of the flash tank, juice inlet and out line sizing, flash vent pipe sizing ..etc.with online calculation sheet.

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Post Author: siva alluri

The aim of this Blog "sugarprocesstech" is Providing basic to advance knowledge in sugar process industry and providing maximum calculation regarding capacity and equipment design online calculators .

15 thoughts on “Flocculants Used in Sugar Processing | Flocculant Dosing Calculation

    DAYANAND HIREMATH

    (October 4, 2017 - 4:55 pm)

    Nice information

    Hazen elmasry

    (October 25, 2017 - 9:20 pm)

    Give me more details about floculation and sedimentation of cane sugar juice with cationic and anionic co_polymer or home polymer

      siva alluri

      (October 27, 2017 - 2:07 pm)

      Ok sir
      we will provide in separate article for that
      Clarifier setting process.
      If you having knowledge related to this topic please submit in word doc. we will publish according to your good name.
      Contact mail: sugarprocesstech@gmail.com
      Thank you

    krishna toragal

    (November 1, 2017 - 1:00 am)

    nice topic

      siva alluri

      (November 1, 2017 - 1:01 pm)

      Thank you sir
      The “www.sugarprocesstech.com” invites to all sugar technologists to share your knowledge, achievements in your working organization and new developments and technologies in sugar industry and its concerned units. It is very much helpful to show your identity to the world at the same time it will helpful to another technologist to enhance their insight and enhance great execution in there working. This website also provides the basic knowledge in sugar industry technologies and equipment design calculation with online calculators.
      sugarprocesstech@gmail.com

    krishna toragal

    (November 1, 2017 - 1:01 am)

    nice

    Umakant Paul

    (January 30, 2018 - 12:36 am)

    Sir I want Refinery Telo clarifier calculation and FFE calculation

      siva alluri

      (January 30, 2018 - 1:36 pm)

      Mr.Umakant
      Definitely we will provide soon melt clarification system calculation

    Kennias Musasa

    (March 16, 2018 - 6:57 am)

    well explained.

    narendra jain

    (April 13, 2018 - 10:15 am)

    well explained to learners and useful for professionals also as it is online available.

    Surendra singh

    (April 28, 2018 - 8:45 am)

    Sir,please tell me about short retention time clarifier design and calculation all about it.

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