Vacuum apparatus for multiple-bed industrial hide driers, and drier including the apparatus

A vacuum apparatus for multiple-bed industrial hide driers, wherein each bed has a heating surface on which the hides to be dried are placed and a cover that provides a hermetic seal, said apparatus comprising a circuit with an open end, along which are arranged in series:

• at least one vapor manifold associated with each bed to collect vapors released by the hides;
• a condenser inserted in each manifold;
• at least one main vacuum pump, said main vacuum pump being suitable to gradually reduce absolute pressure in the circuit to a first value corresponding to a first vapor equilibrium temperature, said apparatus further comprising:
• a first and a second condensate separator arranged at an output of said condenser;
• a secondary aspiration device arranged upstream of said main vacuum pump and downstream of said first and second condensate separators to operate almost exclusively on dry air, said secondary aspiration device being suitable to continuously operate in series with said vacuum pump when said first value of the absolute pressure is reached so as to further reduce the pressure of the circuit to a second value lower than said first value with a result of at least one of (a) instantly increasing evaporation and (b) reducing the vapor equilibrium temperature to a value which is lower than said first vapor equilibrium temperature.