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Dryers

Drying is vital unit operation used in pharmaceutical, Chemical and Agro-chemical industry.
​It is a unit operation in which solvent or water traces are removed by thermal means.
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Contents :
1. What is drying ?
2. What are types of dryers ?
3. What is general operation principles ?
4 What are the parts of dryer ?
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Common types of dryers used in our API industry are:
  • Vacuum tray dryer
  • Rotocone vacuum dryer
  • Fluid bed dryer
  • Rotary Vacuum Paddle Dryer

Vacuum Tray Dryer (VTD)

Vacuum Tray Dryer :

Material is dried in tray which are placed on shelf and with the help of vacuum, hence it is known as Vacuum tray dryer. Material is dried by use of heat and vacuum. Heat is required to raise the temperature, this leads to boiling of solvent which is trapped in lumps and vacuum is applied to lower the boiling point of solvent.

By application of heat and vacuum, solvent / water traces evaporated and material is getting dried.

This dryer is generally used for those products where drying temperature is low (Some products are heat sensitive, it may decomposes at high temperatures) and / or solvent base material (Safety point of view).

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Major parts of Vacuum tray dryer:

  1. Tray: Material is spread over tray for drying.

  2. Shelf: Trays are placed on shelf. Hot water is circulated through shelf and getting heated. Shelf transfers heat to tray where material is spread.  

  3. Vacuum pump: This is required to provide vacuum in vacuum tray dryer.

  4. Chamber: This is outer case of vacuum tray dryer. Shelf are fitted in chamber.

  5.  Pump: This is required to circulate hot water as heating media.

  6. Hot water generation tank: This tank generates hot water by using steam which is required for drying.

  7. HMI panel operation: All utility operation is to be handled through HMI panel. (Vacuum Pump ON/OFF is to be done manually).

Vacuum tray Dryer

Fluid Bed Dryer (FBD)

Fluid Bed dryer :

Material is dried under hot air fluidization, hence it is known as Fluid Bed dryer. Material is dried by use of hot air. Heat is required to raise the temperature, this leads to boiling of solvent/water which is trapped in lumps and air is required to fluidize the material bed and carryover of solvent/ water along with hot air stream. By application of heat and air flow, solvent / water traces evaporated and material is getting dried. This dryer is generally used for those products where drying temperature is high and / or water base material.

 

Major parts of Fluid Bed dryer:

  1. Bowl: Material is charged and here material dried by hot air.

  2. Jack chamber: Bowl is fixed on jack chamber. It is entry portion of hot air.

  3. Retarding chamber: Dryer finger bag fixed here to avoid material carryover along with air stream.

  4. Blower: It is provided at air flow discharge end of fluid bed dryer. It creates air flow during drying operation.

  5. Air preparation unit: Air is filtered through 10µ, 3µ and HEPA filter and heated by steam coil. This filtered and heated air fluidizes and dries material and finally leaves the dryer.

  6. Heating system: It is a part of Air preparation unit.  Air is heated by steam coil. Steam is circulated through coil.

  7. Cooling System: It is a part of Air preparation unit. Cooling damper is provided to cool the air. This cooling is by taking fresh filtered air from atmosphere.

  8. HMI panel operation: All utility operation is to be handled through HMI panel. (Vacuum Pump ON/OFF is to be done manually).

Fluid Bed Dryer

Rotocone Vacuum Dryer (RCVD)

Rotocone Vacuum dryer :

Material is dried in cone shaped rotating chamber in the presence of vacuum, hence it is known as Rotocone Vacuum dryer. Material is dried by use of heat and vacuum. Heat is required to raise the temperature, this leads to boiling of solvent which is trapped in lumps and vacuum is applied to lower the boiling point of solvent.

By application of heat and vacuum, solvent / water traces evaporated and material is getting dried.

This dryer is generally used for those products where drying temperature is low (Some products are heat sensitive, it may decomposes at high temperatures) and / or solvent base material (Safety point of view).

Drying rate of material in Rotocone Vacuum dryer is faster than Vacuum tray dryer. This is because, Material remains stagnant in vacuum tray dryer. In some cases, this benefit may come with one concern that material gets converted in round lumps and results into trouble in drying.

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Major parts of Rotocone Vacuum dryer:

  1. Rotocone chamber: Material is charged and here material dries along with rotation.

  2. Vacuum Filter: This is provided at vacuum inlet position with vacuum mike having externally provision of 5 micron of filter bag size to avoid any contamination through line (during vacuum/nitrogen application)

  3. Vacuum pump: This is required to provide vacuum in rotocone vacuum dryer.

  4. Pump: This is required to circulate hot water as heating media.

  5. Hot water generation tank: This tank generates hot water by using steam which is required for drying.

  6. HMI panel operation: All utility operation is to be handled through HMI panel. (Vacuum Pump ON/OFF is to be done manually) 

Rotocone Vacuum Dryer

Rotary Vacuum Paddle Dryer (RVPD)

Rotary Vacuum Paddle Dryer :

Material is dried in cylindrical shaped chamber with provision of agitator in the presence of vacuum. Material is dried by use of heat and vacuum. Heat is required to raise the temperature, this leads to boiling of solvent which is trapped in lumps and vacuum is applied to lower the boiling point of solvent.

By application of heat and vacuum, solvent / water traces evaporated and material is getting dried.

Agitator is also having the utility provision and is used as dual way, means material scrapping/racking as well as drying of the material with the help of utility provision

This dryer is generally used for solvent base material for those products where drying temperature is low (Some products are heat sensitive, it may decomposes at high temperatures).

Drying rate of material in Rotary Vacuum Paddle Dryer is faster than Rotocone Vacuum Dryer and Vacuum tray dryer. This is because, Material remains stagnant in vacuum tray dryer. In case of Rotocone Vacuum Dryer, the material gets converted in round lumps and results into trouble in drying which is not the case in Rotary Vacuum Paddle Dryer due to agitator provision which constantly rotates and do not allow the material to form the lumps.

 

Major parts of Rotary Vacuum Paddle Dryer:

  1. Cylindrical chamber: Material is charged and here material dries along with rotation.

  2. Dust collector bags: This is provided at vacuum inlet position having externally provision of 5 micron of filter bag size to avoid any contamination through line (during vacuum/nitrogen application)

  3. Vacuum pump: This is required to provide vacuum in rotocone vacuum dryer.

  4. Pump: This is required to circulate hot water as heating media.

  5. Hot water generation tank: This tank generates hot water by using steam which is required for drying.

  6. HMI panel operation: All utility operation is to be handled through HMI panel. (Vacuum Pump ON/OFF is to be done manually)

  7. Power Pack System: This is required for body retraction operation while changeover cleaning.  

Rotary Vacuum Paddle Dryer
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