Variable volume vacuum drying chamber

An apparatus for reducing the moisture content of a material, the apparatus comprising:

• a variable volume chamber, adapted to receive such material for reducing the moisture content of the material, which variable volume chamber comprises side-walls, a bottom wall extending from the side-walls and inclined downwards to a material outlet, and a resilient diaphragm extending across the top of the side-walls to close the chamber;
• heating means within the chamber arranged to heat the material by direct contact with the material;
• and
• pumping means connected to the chamber for pumping fluid from the chamber and capable of maintaining a sub-atmospheric pressure equivalent to at least 16 inches of mercury below atmospheric pressure in the chamber sufficient to substantially reduce heat input from the heating means required to heat material within the chamber;
• the arrangement being such that, in use, the chamber is filled with material, the pumping means pumps fluid from the chamber to create a sub-atmospheric pressure therein, the variable volume chamber reduces in volume so that external pressure is transmitted to the material within the chamber and no substantial pressure load is carried by the walls of the chamber, and material within the chamber is heated by the heating means to cause vaporization of moisture in the material at a temperature below the boiling point of water at atmospheric pressure, the vaporized moisture being drawn off by the pumping means.

An apparatus for reducing the moisture content of a material, the apparatus comprising:

• a variable volume chamber, adapted to receive such material for reducing the moisture content of the material, which variable volume chamber comprises side-walls, a bottom wall extending from the side-walls and inclined downwards to a material outlet, and a resilient diaphragm extending across the top of the side-walls to close the chamber;
• heating means within the chamber arranged to heat the material by direct contact with the material;
• a condenser connected to the variable volume chamber;
• a water/vapor separator connected to the condenser and having one outlet for non-condensable fluid and another outlet for condensate;
• and
• pumping means connected to said one outlet of the water/vapor separator, for pumping fluid from the chamber through the condenser and through the separator, the pumping means being capable of maintaining a sub-atmospheric pressure equivalent to at least sixteen inches of mercury below atmospheric pressure in the chamber sufficient to substantially reduce heat input from the heating means required to heat material within the chamber;
• the arrangement being such that, in use, the chamber is filled with material, the pumping means pumps fluid from the chamber to create a sub-atmospheric pressure therein, condensate is drawn off through the other outlet of the water/vapor separator, the variable volume chamber reduces in volumes so that external pressure is transmitted to the material within the chamber and no substantial pressure load is carried by the walls of the chamber, and material within the chamber is heated by the heating means to cause vaporization of moisture in the material at a temperature below the boiling point of water at atmospheric pressure, the vaporized moisture being drawn off by the pumping means.

An apparatus for reducing the moisture content of a material, the apparatus comprising:

• a variable volume chamber, adapted to receive such material for reducing the moisture content of the material;
• heating means within the chamber arranged to heat the material by direct contact with the material;
• a condenser connected to the variable volume chamber;
• a water/vapor separator connected to the condenser and having one outlet for non-condensable fluid and another outlet for condensate;
• and
• pumping means connected to said one outlet of the water/vapor separator, for pumping fluid from the chamber through the condenser and through the separator, the pumping means being capable of maintaining a sub-atmospheric pressure in the chamber sufficient to substantially reduce heat input from the heating means required to heat material within the chamber;
• the arrangement being such that, in use, the chamber is filled with material, the pumping means pumps fluid from the chamber to create a sub-atmospheric pressure therein, condensate is drawn off through the other outlet of the water/vapor separator, the variable volume chamber reduces in volumes so that external pressure is transmitted to the material within the chamber and no substantial pressure load is carried by the walls of the chamber, and the material within the chamber is heated by the heating means to cause vaporization of moisture in the material at a temperature below the boiling point of water at atmospheric pressure, the vaporized moisture being drawn off by the pumping means.

An apparatus for reducing the moisture content of a material, the apparatus comprising:

• a variable volume chamber adapted to receive such material for reducing the moisture therein, which variable volume chamber is cylindrical about a vertical axis and has regid side-walls;
• heating means for heating the material by direct contact with the material comprising a plurality of cylindrical heating panels disposed concentrically within one another and within the variable volume chamber to define annular spaces for said material, each of which heating panels comprises two sheets bonded together to define channels extending across the panel for a heat source;
• and
• pumping means connected to the chamber for pumping fluid from the chamber and capable of maintaining a sub-atmospheric pressure equivalent to at least 16 inches of mercury below atmospheric pressure in the chamber sufficient to substantially reduce heat input from the heating means required to heat material within the chamber;
• the arrangement being such that, in use, the chamber is filled with material, the pumping means pumps fluid from the chamber to create a sub-atmospheric pressure therein, the variable volume chamber reduces in volume so that external pressure is transmitted to the material within the chamber and no substantial pressure load is carried by the walls of the chamber, and material with the chamber is heated by the heating means to cause vaporization of moisture in the material at a temperature below the boiling point of water at atmospheric pressure, the vaporized moisture being drawn off by the pumping means.