Process equipment vacuum dryers

VAC TRAX is different from other thermal desorption processes in that it is a vacuum dryer. By sealing the drying chamber and reducing the air pressure, a vacuum is created. The vacuum allows a much lower temperature to be used in the dryer, enabling the use of smaller, more transportable equipment. 

The crystalline BHC product is to be dried in a rotary vacuum dryer equipped with a solvent recovery system. The recovered solvents from various operations are to be combined and fractionated. The overhead distillate consisting primarily of benzene is to be reused in the process whereas the chlorobenzol solvents in the bottoms are to be stored for sale as crude monochlorobenzene. 

Essentially atmospheric conditions for all process equipment except vacuum dryer which operates at about 20 in. Hg vacuum... 

Conaform, Double cone vacuum dryers, Patterson Process Equipment Div. 

For drying rubber by a vacuum process it is heated in a closed vessel by steam from which the air and moisture are removed by a vacuum pump. The vacuum dryer is used where fast drying of rubber is required. While a vacuum dryer is an expensive piece of equipment, the cost and upkeep of buildings and saving of time must be set against its prime cost and working expenses. 

To date, only microwave hot-air dryers used principally in flnish drying processes to level-off the moisture content in pasta, crackers or chips, and microwave vacuum dryers custom-made to specific product requirements, are available commercially (Ratti, 2008). Good microwave-assisted drying equipment should have a uniform distribution of the microwave field, provide a movement of the material to be dried, keep the microwave field strength in the drying chamber lower than the dielectric breakdovm strength, and possess an economic dehumidification system. 

The process system consists of two long-tube vertical evaporators, a draft-tube baffled crystallizer, a rotary-drum vacuum filter, and a direct-heat rotary dryer. Also, pumps are needed to move the solution from evaporator 1 to evaporator 2, to recycle the filtrate from the filter to the crystallizer, and to move the magma from the crystallizer to the filter and a heat exchanger is needed to heat the recycle filtrate. However, the purchase costs for the three pumps and the heat exchanger are not considered here because examples for these types of equipment are presented in Section 16.5. For the equipment considered here, assume fabrication from stainless steel, with a material factor of 2 for the ratio of stainless steel cost to carbon steel cost. For the process, using the following size factors and the equations in Table 16.32, the estimated f.o.b. equipment purchase costs at a CE index of 394 are included in the following table. 

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