Method for drying wet particulate matter, wherein the dried particulate matter is a white mineral having a brightness Ry of at least 65% that forms particulate matter through drying in direct superheated steam dryer

Patent metadata

Field	Value
Publication number	US-10190820-B2
Application number	US-201214008679-A
Country	US
Kind code	B2
Filing date	Apr 11, 2012
Priority date	Apr 15, 2011
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

The present invention relates to a method for drying wet particulate matter, wherein at least one feed stream ( 1 ) of wet particulate matter is contacted with superheated steam ( 6 ) within at least one drying chamber ( 40 ) with a mixing system, and the dried particulate matter is discharged as at least one product stream ( 10 ) to obtain the dried particulate matter.

First claim

The invention claimed is:

1. A method for drying wet particulate matter, wherein the dried particulate matter is a white mineral having a brightness Ry of at least 65% measured according to DIN 53163, the method comprising the steps of:
a) providing at least one feed stream of wet particulate matter;
b) providing a recirculation circuit comprising at least one drying chamber, at least one circulation fan, and at least one heat exchanger, wherein the at least one drying chamber comprises a mixing system and mixed particulate matter, at least one inlet for the feed stream of wet particulate matter, at least one inlet for superheated steam, and at least one outlet for exhaust steam, wherein the recirculation circuit includes no fines/steam separator between the at least one outlet of the at least one drying chamber for exhaust steam, the at least one inlet of the at least one drying chamber for the feed stream of wet particulate matter, and the at least one inlet of the at least one drying chamber for superheated steam that is configured to separate particulate matter from the exhaust steam traveling along the recirculation circuit;
c) feeding, either continuously or discontinuously, the at least one feed stream of wet particulate matter into the mixed particulate matter in the at least one drying chamber via the at least one inlet for the feed stream;
d) feeding superheated steam into the at least one drying chamber via the at least one inlet for superheated steam;
e) directly contacting the mixed particulate matter with superheated steam within the at least one drying chamber to dry the mixed particulate matter and exhausting said steam via the at least one outlet for exhaust steam without separating from the exhaust steam any carried particulate matter;
f) feeding the exhaust steam carrying particulate matter from the step (e), without separating from the exhaust steam any carried particulate matter, into the at least one heat exchanger, in which the exhaust steam carrying particulate matter is reheated to provide superheated steam, wherein the exhaust steam carrying particulate matter passes the at least one circulation fan before or after the at least one heat exchanger, and feeding said superheated steam back into the at least one drying chamber via the at least one inlet for superheated steam;
g) splitting an excess steam from at least one position within the recirculation circuit;
h) feeding the excess steam into at least one mechanical compressor, wherein the excess steam is compressed to raise its saturated temperature, using said compressed excess steam as a source of heat in the at least one heat exchanger, and discharging the excess steam as a liquid condensate; and
i) discharging, either continuously or discontinuously, the dried particulate matter as at least one product stream via at least one outlet to obtain the dried particulate matter.

2. The method according to claim 1 , wherein the at least one drying chamber comprises at least one outlet for dried particulate matter and the at least one product stream is discharged via the at least one outlet for dried particulate matter from the at least one drying chamber and/or the remaining recirculation circuit excluding the at least one drying chamber comprises at least one outlet for dried particulate matter and the at least one product stream is discharged via the at least one outlet for dried particulate matter from the recirculation circuit excluding the at least one drying chamber.

3. The method according to claim 1 , wherein the mixing system within the drying chamber is a one, two- or more shafts mixer, a one, two- or more shafts combined mixer and mechanical fluidized bed establisher, or a two shafts combined mixer and mechanical fluidized bed establisher.

4. The method according to claim 1 , wherein the at least one drying chamber has an internal pressure of from 0 to 5 bar.

5. The method according to claim 1 , wherein the at least one drying chamber has an internal pressure of from 0.1 to 1.5 bar.

6. The method according to claim 1 , wherein the at least one drying chamber has an internal pressure of from 0.1 to 0.95 bar.

7. The method according to claim 1 , wherein the at least one drying chamber has an internal pressure of from 1.05 to 1.2 bar.

8. The method according to claim 1 , wherein the superheated steam is superheated water steam and the pressure drop through the recirculation circuit is from 500 to 3000 Pa at a pressure in the at least one drying chamber of 0.8 to 1.2 bar.

9. The method according to claim 1 , wherein the superheated steam is superheated water steam and the pressure drop through the recirculation circuit is from 1000 to 2000 Pa at a pressure in the at least one drying chamber of 0.8 to 1.2 bar.

10. The method according to claim 1 , wherein the excess steam is split from at least one position within the recirculation circuit, wherein the amount of carried particulate matter is found to be lowest.

11. The method according to claim 1 , wherein the excess steam is split from the exhaust steam after leaving the at least one drying chamber and before leaving the at least one circulation fan.

12. The method according to claim 1 , wherein the at least one heat exchanger is a shell and tube heat exchanger.

13. The method according to claim 1 , wherein the at least one mechanical compressor is a centrifugal compressor, a high pressure centrifugal fan, or a positive displacement roots blower.

14. The method according to claim 1 , wherein the at least one mechanical compressor is a high pressure centrifugal fan.

15. The method according to claim 1 , wherein the superheated steam's temperature and the exhaust steam's temperature leaving the at least one drying chamber differs by a temperature difference ΔT R , wherein ΔT R is from 5 to 100° C.

16. The method according to claim 1 , wherein the superheated steam's temperature and the exhaust steam's temperature leaving the at least one drying chamber differs by a temperature difference ΔT R , wherein ΔT R is from 10 to 50° C.

17. The method according to claim 1 , wherein the superheated steam's temperature and the exhaust steam's temperature leaving the at least one drying chamber differs by a temperature difference ΔT R , wherein ΔT R is from 15 to 30° C.

18. The method according to claim 1 , wherein the superheated steam's temperature and the exhaust steam's temperature leaving the at least one drying chamber differs by a temperature difference ΔT R , wherein ΔT R is from 15 to 25° C.

19. The method according to claim 1 , wherein the excess steam's saturated temperature and the compressed excess steam's saturated temperature differs by a temperature difference ΔT E , wherein ΔT E is from 6 to 130° C.

20. The method according to claim 1 , wherein the excess steam's saturated temperature and the compressed excess steam's saturated temperature differs by a temperature difference ΔT E , wherein ΔT E is from 11 to 80° C.

21. The method according to claim 1 , wherein the excess steam's saturated temperature and the compressed excess steam's saturated temperature differs by a temperature difference ΔT E , wherein ΔT E is from 15 to 60° C.

22. The method according to claim 1 , wherein the excess steam's saturated temperature and the compressed excess steam's saturated temperature differs by a temperature difference ΔT E , wherein ΔT E is from 20 to 45° C.

23. The method according to claim 1 , wherein the superheated steam's tempera

Assignees

• Bergset Olav
• Cremaschi Alain
• Gutsche Robert
• Hautcoeur Ludovic
• Omya Int Ag

Inventors

• Bergset Olav
• Cremaschi Alain
• Gutsche Robert
• Hautcoeur Ludovic

Classifications

• F26B2200/18

  Sludges, e.g. sewage, waste, industrial processes, cooling towers · CPC title

• F26B23/004

  by compressing and condensing vapour in exhaust gases, i.e. using an open cycle heat pump system · CPC title

• C01F11/185

  After-treatment, e.g. grinding, purification, conversion of crystal morphology · CPC title

• F26B17/20

  the axis of rotation being horizontal or slightly inclined · CPC title

• Y02B30/52

  Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency · CPC title