EVAPORATION DRYER AND METHOD FOR OPERATING SAME

Abstract

The invention relates to an evaporation dryer (1) for drying particles, havinga process chamber (10) with at least one product inlet (11) for supplying the particles to be dried into the process chamber (10) and a product outlet (12) for discharging dried particles from the process chamber (10), a heat exchanger (20) arranged within the process chamber (10), having at least one inlet (21, 211) into the heat exchanger (20) for pressurized steam as process steam and at least one condensate outlet (22, 222) from the heat exchanger (20), whereinthe at least one condensate outlet (22, 222) is connected to an expansion tank (30), wherein at least one pump (40) is connected to the expansion tank (30), and the expanding steam is pumped out of the expansion tank (30) and supplied to the process steam.

Claims

1. An evaporation dryer for the drying of particles, comprising: a process chamber having at least one product inlet for the feeding of particles to be dried into a process chamber space and having a product outlet for evacuation of dried particles from the process chamber; a heat exchanger arranged within the process chamber, the heat exchanger comprising at least one inlet for highly pressurized steam as heating steam and at least one condensate outlet connected to an expansion tank, wherein the expansion tank is connected to at least one pump which pumps off flash steam from the expansion tank and supplies the flash steam to the heating steam.

2. The evaporation dryer as claimed in claim 1, wherein the at least one pump is configured as a steam jet pump having a motive steam port, and wherein at least a partial flow of the heating steam is obtained at the motive steam port.

3. The evaporation dryer as claimed in claim 1, wherein the at least one pump is configured as a mechanical suction pump.

4. The evaporation dryer as claimed in claim 1 wherein a pressure within the expansion tank is set beneath a pressure of the heating steam.

5. The evaporation dryer as claimed in claim 1 wherein the heat exchanger is of multi-stage construction having at least a first stage and a second stage, wherein to the first stage comprises a mixed steam of the heating steam and the flash steam, and wherein the second stage is configured such that the heating steam is fed to the heat exchanger.

6. The evaporation dryer as claimed in claim 5, wherein the first and second stages are assigned separate condensate tanks which are coupled to the expansion tank.

7. The evaporation dryer as claimed in claim 6, wherein the separate condensate tanks are coupled to the expansion tank via a control valve.

8. The evaporation dryer as claimed in claim 6, wherein the separate condensate tanks each have a pressure level equating to or below a pressure of the heating steam.

9. The evaporation dryer as claimed in claim 1, wherein the evaporation dryer is configured as a fluidized-bed evaporation dryer, wherein the process chamber is a ring-like process chamber and wherein the evaporation dryer further comprises a conveying device for feeding a fluidizing agent into the process chamber, and wherein in the process chamber is comprised of configured cells which extend in a vertical direction, wherein one cell of the configured cells forms a discharge cell, which is either not, flowed through from below by the fluidizing agent or is flowed through in a reduced amount by the fluidizing agent, and wherein a lower end of the one cell is configured as a product outlet, and wherein each of the configured cells is open at an upper end.

10. The evaporation dryer as claimed in claim 1 further comprises a plurality of pumps connected in parallel to one another, wherein said plurality of pumps includes said at least one pump.

11. The evaporation dryer as claimed in claim 1 wherein an overpressure prevails in the process chamber.

12. The evaporation dryer as claimed in claim 6 further comprising a connecting line from the expansion tank leads to a mixing point arranged downstream of a steam generating device, wherein the heating steam is mixed with condensate from the expansion tank and/or the separate condensate tanks in the mixing point.

13. The evaporation dryer as claimed in claim 1 further comprising a control valve positioned between the at least one pump and the steam generating device.

14. The evaporation dryer as claimed in claim 1 wherein condensate from the at least one condensate outlet is conducted from heating plates or heating devices in or outside the process chamber to the expansion tank directly or via condensate tanks or condensate drains.

15. A method for operating an evaporation dryer for the drying of particles, comprising: providing an evaporation dryer with a process chamber having at least one product inlet through which particles to be dried are introduced into a process chamber space and having a product outlet, through which dried particles are evacuated from the process chamber, a heat exchanger into which, via at least one inlet, highly pressurized steam is passed as heating steam and from which, through at least one condensate outlet, condensate is led off and supplied to an expansion tank; pumping off flash steam via at least one pump; supplying the flash steam to the heating steam.

16. The method as claimed in claim 15, wherein the heating steam is fed to the evaporation dryer from various steam generating devices in different steam qualities.

17. The evaporation dryer as claimed in claim 1 further comprising a connecting line from the expansion tank leads to a mixing point arranged downstream of a steam generating device, wherein the heating steam is mixed with condensate from the expansion tank in the mixing point.

Description

REFERENCE SYMBOL LIST

[0033] 1 evaporation dryer

[0034] 2 steam generating device

[0035] 3 mixing point

[0036] 10 process chamber

[0037] 11 product inlet

[0038] 12 product outlet

[0039] 13 store

[0040] 14 14 expansion cyclone

[0041] 15 cylindrical housing

[0042] 16 conveying device

[0043] 17 ejector

[0044] 20 heat exchanger

[0045] 21 heating steam inlet, upper heat exchanger

[0046] 22 condensate outlet, upper heat exchanger

[0047] 23 upper heat exchanger

[0048] 25 lower heat exchanger

[0049] 28 internal heating surfaces

[0050] 30 expansion tank

[0051] 33 condensate tank, upper heat exchanger

[0052] 34 flash steam line

[0053] 35 condensate tank, lower heat exchanger

[0054] 36 condensate tank

[0055] 40 pump

[0056] 41 motive steam port

[0057] 42 condensate line to the mixing point

[0058] 53 control valve, upper heat exchanger

[0059] 54 control valve for motive steam

[0060] 55 control valve, lower heat exchanger

[0061] 57 control valve for dryer pressure

[0062] 211 heating steam inlet, lower heat exchanger

[0063] 222 condensate outlet, lower heat exchanger