Variable flow rate dehumidification plant and process for granular materials

• US 20080295354A1
• Filed: 05/23/2008
• Published: 12/04/2008
• Est. Priority Date: 05/25/2007
• Status: Active Grant

• Current Assignee: Moretto S.p.A. (Faita SA)
• Original Assignee: Moretto S.p.A. (Faita SA)
• Inventors: Moretto, Renato
• Granted Patent: US 8,021,462 B2
• Time in Patent Office: Days
• US Class Current: 34/476
• CPC Class Codes: B29B 13/065 of powder or pellets
• CPC Class Codes: B29B 9/16 Auxiliary treatment of granules
• CPC Class Codes: F26B 21/083 by using sorbent or hygroscopic materials, e.g. chemical substances, molecular sieves

Abstract

The present invention relates to a dehumidification plant for a granular material, comprising at least one hopper (2) having at least one loading mouth (3a) and one discharge mouth (3) for granular material, at least one upper feeding mouth in the at least one hopper (2) and at least one lower delivery mouth of a gaseous medium therefrom, humidity absorbent means (51, 52) designed to absorb the humidity conveyed by the gaseous medium; at least two towers (29, 36) arranged to contain the absorbent means (51, 52); supplying means designed to feed the gaseous medium to the at least one hopper (2) and the at least two towers (29, 36); at least one electronic control unit (46); detection means arranged to detect process variables of the plant and electrically connected with the at least one electronic control unit (46). The plant further comprises distribution means designed to distribute gaseous medium coming from at least one (29, 36) of the at least two towers thereby feeding it to at least another tower (36, 29) from among the at least two towers, the distribution means being controllable by the at least one electronic control unit (46) between at least one open position, in which at least one portion of the gaseous medium contained in the at least one of the at least two towers (29, 36) is fed to the at least another (36, 29) of the at least two towers, and at least one closed position.

Claims

1. A dehumidification plant for a granular material, comprising at least one hopper having at least one loading mouth and one discharge mouth for said granular material, at least one upper feeding mouth in said at least one hopper and at least one lower delivery mouth of a gaseous medium therefrom, humidity absorbent means designed to absorb the humidity conveyed by said gaseous medium;

at least two towers arranged to contain said absorbent means;

supplying means designed to feed said gaseous medium to said at least one hopper and said at least two towers;

at least one electronic control unit;

detection means arranged to detect process variables of said plant and electrically connected with said at least one electronic control unit, comprising distribution means designed to distribute gaseous medium coming from at least one of said at least two towers thereby feeding it to at least another tower from among said at least two towers, said distribution means being controllable by said at least one electronic control unit between at least one open position, in which at least one portion of said gaseous medium contained in said at least one of said at least two towers is fed to said at least another of said at least two towers, and at least one closed position.

2. A plant according to claim 1, wherein said distribution means comprises at least one first valve means, at least one duct intended to place said first valve means in fluid communication with at least one of said at least two towers, at least one duct between at least another of said at least two towers and said first valve means.

3. A plant according to claim 2, comprising at least one emission duct of said gaseous medium between said first valve means and said at least one hopper.

4. A plant according to claim 2, wherein said first valve means comprises a slide valve.

5. A plant according to claim 2, wherein said distribution means comprises pressurization means for said gaseous medium.

6. A plant according to claim 5, wherein said pressurization means of said gaseous medium comprises at least one blower arranged to intercept said at least one duct intended to place in fluid communication said first valve means and at least one of said at least two towers.

7. A plant according to claim 2, wherein said distribution means comprises pressurization means for said gaseous medium, said pressurization means of said gaseous medium comprising at least one blower arranged to intercept said at least one duct intended to place in fluid communication said first valve means and at least one of said at least two towers, and said distribution means comprises at least one adjusting device arranged to adjust the rotation speed of said blower.

8. A plant according to claim 7, wherein said adjusting device of the rotation speed of said blower is controllable by said at least one electronic control unit.

9. A plant according to claim 1, wherein said process variable detection means comprises at least one temperature sensor set to detect the temperature at a lower portion of at least one of said at least two towers.

10. A plant according to claim 1, wherein said process variable detection means comprises at least one temperature sensor set to detect the temperature at an upper portion of at least one of said two towers.

11. A plant according to claim 2, wherein said supply means of said gaseous medium comprises at least a second valve means, at least one delivery duct of gaseous medium between said at least one first valve means and said at least two towers, and at least one fluid connection duct between said at least one second valve means and said at least one hopper, and in that said distribution means comprises at least one duct intended to place in fluid communication said first valve means and said at least one second valve means, and at least one duct arranged to place in fluid communication said first valve means and said second valve means.

12. A plant according to claim 11, comprising an actuation device of said second valve means.

13. A plant according to claim 1, comprising heating/cooling means of said gaseous medium set to cool/heat said gaseous medium supplied between said hopper and at least one of said at least two towers.

14. A plant according to claim 13, comprising at least one supply duct of said gaseous medium between at least one of said at least two towers and said cooling/heating means, a connection duct between said cooling/heating means and said at least one hopper, at least one temperature sensor electrically connected with said electronic control unit and arranged to detect the temperature in said connection duct.

15. A plant according to claim 13, wherein said heating/cooling means of gaseous medium comprises at least one heat exchanger designed to cool said gaseous medium conveyed between said at least one hopper and said at least two towers, pressurization or pumping means of said gaseous medium, variator means arranged to vary the rotation speed of said pressurization or pumping means, at least one external refrigeration unit for a refrigerant fluid to be fed to said at least one heat exchanger.

16. A plant according to claim 15, comprising at least one delivery duct of refrigerant fluid from said external refrigeration unit to said at least one heat exchanger, at least one delivery duct of refrigerant fluid from said at least one heat exchanger to said at least one external refrigeration unit, at least one third adjusting valve means intended to intercept said at least one delivery duct of refrigerant fluid coming from said external refrigeration unit to said at least one heat exchanger, and/or at least one emission duct of refrigerant fluid from said at least one heat exchanger to said at least one external refrigeration unit, and actuation means of said at least one adjusting valve controllable by said electronic control unit.

17. A plant according to claim 15, comprising at least one temperature probe placed at a suction mouth of said pressurization or pumping means for said gaseous medium.

18. A dehumidification plant according to claim 1, comprising measuring means designed to measure the flow rate of said gaseous medium.

19. A plant according to claim 18, wherein said measuring means of the flow rate comprises a Venturi meter nozzle provided with a respective differential pressure sensor, and are electrically connectable to said at least one electronic control unit.

20. A plant according to claim 1, wherein said absorbent means comprises molecular sieves.

21. A plant according to claim 1, comprising a user interface including a video unit and data insertion means, said user interface being designed to store processing parameters and characteristics related to the granular materials to be processed in the electronic control unit.

22. A plant according to claim 21, wherein said electronic control unit comprises a first pre-storage portion of a table, in which a list is indicated of a first array of granular plastic materials together with respective main processing parameters that one expects to use in the plant, and a second storage portion for storing parameters of a second array of granular plastic materials.

23. A plant according to claim 1, comprising at least one heating means arranged upstream of at least one of said at least two towers.

26. A process of at least one tower of a dehumidification plant of a granular material, comprising the following steps in sequence:

detecting the process variables of said plant and adjusting, as a function of the detected process variables, the supply flow of gaseous medium to said at least one tower, to be carried out by means of a plant according to claim 17, comprising the following sequential steps;

detecting at least one temperature signal by means of said temperature probe and by means of said at least one probe located at at least one of said at least two towers; and

adjusting the opening/closing of said at least one adjusting valve as a function of the signals detected in said detection step, thereby obtaining a predetermined temperature for said gaseous medium to be fed to said at least two towers in processing phase.

27. A process of at least one tower of a dehumidification plant of a granular material, comprising the following steps in sequence:

detecting the process variables of said plant and adjusting, as a function of the detected process variables, the supply flow of gaseous medium to said at least one tower, that can be carried out by means of a plant according to claim 7, comprising an adjusting step of the flow of said gaseous medium intended to regenerate said absorbent means as a function of the granular material to be dehumidified and/or type of absorbent means and/or said process variable detection means.

28. A process of at least one tower of a dehumidification plant of a granular material, comprising the following steps in sequence:

detecting the process variables of said plant and adjusting, as a function of the detected process variables, the supply flow of gaseous medium to said at least one tower, that can be achieved by means of a plant according to claim 15, comprising;

detecting the flow rate by means of said measuring means of the flow rate of said gaseous medium;

detecting the temperature at said gaseous medium inlet mouth in said at least one hopper; and

controlling said rotation speed variation means as a function of the detected data.

29. A process of at least one tower of a dehumidification plant of a granular material, comprising the following steps in sequence:

detecting the process variables of said plant and adjusting, as a function of the detected process variables, the supply flow of gaseous medium to said at least one tower, that can be carried out by means of a plant according to claim 23, wherein the emission of said gaseous medium coming from at least one of said at least two towers when in processing phase to at least one of said at least two towers in regeneration phase occurs when said heater upstream of said at least one of said at least two towers in regeneration phase is turned on.

24. A regeneration process of at least one tower of a dehumidification plant of a granular material, comprising the following steps in sequence:

detecting the process variables of said plant and

adjusting, as a function of the detected process variables, the supply flow of gaseous medium to said at least one tower.

25. A process according to claim 24, wherein regeneration process of at least one tower of a dehumidification plant of a granular material, comprising the following steps in sequence:

detecting the process variables of said plant and

adjusting, as a function of the detected process variables, the supply flow of gaseous medium to said at least one tower.