Steam compression dryer

1. An apparatus, comprising:

a container ( 30 ), configured to receive material to be dried ( 40 ) and having a container inlet ( 50 ) and a container outlet ( 42 );

a blower ( 110 ) that is configured to motivate a first air-vapor mixture flow via the container inlet through said material and via the container outlet ( 40 );

a heating device ( 130 ) that is configured to heat said first air-vapor mixture;

a selector ( 100 ) with at least two states:

in a first state, the selector directs most of the first air-vapor mixture driven by the blower from said container outlet to said container inlet in a closed cycle; and

in a second state, the selector exchanges most of the first air-vapor mixture with air located outside the apparatus, or enables to transfer part of the heat from said first air-vapor mixture toward a fluid located outside the apparatus;

a compressor ( 140 ) that is configured to compress and motivate a part of said first air-vapor mixture flow as a second air-vapor mixture flow to flow through a first heat exchanger ( 120 ) and through a second heat exchanger ( 160 ) in an open process;

a pressure reducing device ( 150 ) that is configured to reduce the pressure of said second air-vapor mixture downstream said first heat exchanger ( 120 ),

wherein:

said first heat exchanger is configured to transfer heat between said compressed second air-vapor mixture toward said first air-vapor mixture, and

said second heat exchanger is configured to remove excess heat from the second air-vapor mixture toward outside of the apparatus.

2. The apparatus according to claim 1 wherein part of the second air-vapor mixture condenses, thereby creating a gas and liquid mixture within the first and/or the second heat exchanger.

3. The apparatus according to claim 2 wherein said gas and liquid mixture are separated using a separator to a gas portion and a liquid portion.

4. The apparatus according to claim 3 in which said gas portion returns to said first air-vapor mixture.

5. The apparatus according to claim 3 , wherein the pressure reducing device comprises a turbine configured to recover pressure energy contained in said gas portion which exits said separator.

6. The apparatus according to claim 5 , in which the gas and liquid mixture flow exiting the turbine is separated using a separator and a selector is used to decide whether said gas portion is returned to the first air-vapor mixture or to flow to said second heat exchanger.

7. The apparatus according to claim 5 , wherein said turbine and said compressor are built from one mechanical assembly.

8. The apparatus according to claim 1 further comprising a controller to control at least some components and/or indicators of the apparatus.

9. The apparatus according to claim 8 , in which at least one of the physical parameters comprising pressure, volume, temperature, humidity, relative humidity, air flow and conductivity is measured by a sensor and data representative of the at least one of the physical parameters is fed to said controller.

10. The apparatus according to claim 1 , where the first and second heat exchangers are combined to a single mechanical structure.

11. The apparatus according to claim 1 , comprises a two-state valve configured in a first configuration to allow the second air-vapor flow to bypass the pressure reducing device, and in a second configuration enforces the second air-vapor flow to pass through the pressure reducing device.

12. The apparatus according to claim 1 , wherein an operating pressure of the container is less than one bar.

13. The apparatus according to claim 1 which includes a pressure tight sealable lid and an opening to enable insertion and removal of the material to be dried into and from said container and a locking mechanism configured to lock said lid.

14. The apparatus according to claim 1 where the functionality of said second heat exchanger is implemented as allowing to allow heat loss to the environment.