Method and apparatus for treating process water

Patent metadata

Field	Value
Publication number	US-9802838-B2
Application number	US-201113996025-A
Country	US
Kind code	B2
Filing date	Dec 6, 2011
Priority date	Dec 20, 2010
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

A method and apparatus are disclosed for treating process water which is loaded with gaseous compounds and/or possibly with solids and comes from a wet-cleaning installation for cleaning process gas, e.g., from a melt-reduction subassembly or from a direct-reduction subassembly. Process water is introduced in a tank in a first process stage and degassed on the basis of reduced solubility of the dissolved compounds. The tank has, on its upper side, a gas-collecting chamber, in which the separated-off gases are collected and from which these are discharged. Likewise, the treated process water is discharged from the tank via a drainage means.

First claim

What is claimed is:

1. An apparatus for degassing process water loaded with dissolved gaseous compounds comprising at least one of carbon dioxide CO 2 , carbon monoxide (CO), volatile organic substances, and solids, the process water received from a wet-cleaning installation for cleaning process gas, the apparatus comprising:
in a first process stage including in a sealable tank with a supply line at least one entry element for entering process water into the tank,
wherein the tank comprises a gas-collecting chamber on a top side of the tank for receiving gaseous compounds separated from the process water, and
a gas drain for the separated gases and a floating sludge drain is provided in an upper area of the gas-collecting chamber,
wherein:
the tank comprises:
a drain for the treated process water, and
a discharge facility for discharging solids separated from the process water, the discharge facility being provided in an area of a lowest point of the tank,
wherein the drain includes at least one of a sealable outlet, a pump, and at least one hydrocyclone, the drain draining treated process water from the tank,
the at least one entry element subjects the process water to a drop in pressure, and the at least one entry element distributes the process water in the gas-collecting chamber, and
the at least one entry element comprises a nozzle which finely distributes the process water in the gas-collecting chamber.

2. The apparatus of claim 1 , wherein the at least one entry element comprises a valve.

3. The apparatus of claim 1 , wherein the at least one entry element comprises a diaphragm.

4. The apparatus of claim 1 , wherein the at least one entry element comprises a siphon.

5. The apparatus of claim 1 , wherein the tank further comprises a scraper for removing foam or floating sludge from the degassed process water in the tank.

6. The apparatus of claim 1 , wherein the gas drain is connected to at least one of a heater, and a filter, the heater being configured to dry the gases discharged from the tank, and the filter being configured to separate gaseous substances.

7. The apparatus of claim 1 , comprising a gas distributor on a lower side of the tank for introducing a carrier gas for the cleaning-off of dissolved or suspended solids, wherein the gas distributor comprises a plurality of openings and the gas distributor is arranged at least in an area of the tank below the gas-collecting chamber.

8. The apparatus of claim 1 , wherein at least one of a gasification tube, a gasification rod, a gasification vessel, and a dynamic gasification facility is provided in the tank for disperging a carrier gas in the process water and for increasing the exchange of materials surface for at least one gas distributor.

9. The apparatus of claim 1 , wherein the apparatus comprises in a second process stage a column which is embodied as at least one of a spray tower with a separation by contact of the sprayed process water by means of a gas flow, at least one bubble column with a separation by blocking a stripping gas into the process water, and a packed column with a separation by means of bulky solids made of carbon, coke or ore.

10. The apparatus of claim 1 , comprising at least one burner for oxidation or thermal decomposition of the separated gaseous compounds from at least one of the first process stage and a second process stage.

11. The apparatus of claim 1 , wherein the tank is a cylinder open at the bottom, which is immersed at least partially into process water.

12. The apparatus of claim 1 , wherein the drain for the treated process water feeds the treated process water, in a second process stage, into a column for further degassing of the process water.

13. A method for degassing process water loaded with dissolved gaseous compounds comprising at least one of carbon dioxide (Co 2 ), carbon monoxide (CO), volatile organic substances, and solids, the process water coming from a wet-cleaning installation for cleaning process gas, the method being performed with the apparatus of claim 1 and comprising:
introducing the process water into the tank of the first process stage that is sealed off from the surrounding atmosphere by the at least one entry element,
for degasification of the process water, subjecting the process water is subjected to the drop in pressure upon entry into the tank, thereby resulting in a degasification due to the reduced solubility of the dissolved gases,
controlling a fill level in the gas-collecting chamber of the tank such that the separated gases collect above a fill level for discharge from the tank,
discharging from the tank the degassed process water and solids deposited in the area of the lowest point of the tank from the process water in the form of sediments, and
drawing off the degassed process water via at least one of the sealable outlet, the pump, and the at least one hydrocyclone, and discharging the solids via the discharge facility.

14. The method of claim 13 , comprising introducing the process water into the gas-collecting chamber in order to increase the exchange of materials surface.

15. The method of claim 13 , wherein the drop in pressure is generated upon entry of the process water through the at least one entry element, which comprises at least one of a valve, a diaphragm, and a siphon.

16. The method of claim 13 , comprising drying the gases discharged from the tank in at least one of a droplet separator and a heating facility, supplying the dried gases to at least one of a filter and an absorber, and separating the organic substances.

17. The method of claim 13 , wherein the gases discharged from the tank are combusted or heated, wherein the organic substances are destroyed by means of at least one of oxidation and thermal decomposition.

18. The method of claim 13 , wherein the drop in pressure amounts to 0.1-10 bar.

19. The method of claim 13 , comprising introducing a carrier gas comprising air, nitrogen or steam into the tank to assist with the degasification and cleaning process of dissolved or suspended solids on the underside of the tank.

20. The method of claim 19 , comprising using the floating sludge drain to remove from the gas-collecting chamber foam or floating sludge arising during degasification or by the cleaning-off of suspended solids.

21. The method of claim 13 , wherein the pressure in the tank is reduced as a function of the temperature of the process water such that the process liquid boils.

22. The method of claim 13 , comprising re-supplying at least one part of the process water discharged from the tank to the first process stage for further treatment.

23. The method of claim 13 , comprising routing the treated process water to a further process stage including at least one column suited to stripping the process water, wherein a further separation of at least gaseous compounds from the process water occurs.

24. The method of claim 23 , wherein the separation in the column in a spray tower occurs by contact of the sprayed process water with a gas flow by blowing a stripping gas into the process water with fillers or components for increasing the exchange of materials surface.

25. The method of claim 23 , wherein in the first process stage, the solids are discharged at least partially in the form of sludge, and the gaseous compounds and gaseous compounds remaining in the treated process water are discharged in the further process stage.

Assignees

• Gstoettenmayr Alois
• Heckmann Hado
• Lukschander Kurt
• Millner Robert
• Schmidt Ulrike
• Siegl Helmut
• Wurm Johann
• Choi Chong Won
• Yoon Seok Min
• Posco
• Primetals Technologies Austria GmbH

Inventors

• Gstoettenmayr Alois
• Heckmann Hado
• Lukschander Kurt
• Millner Robert
• Schmidt Ulrike
• Siegl Helmut
• Wurm Johann
• Choi Chong Won
• Yoon Seok Min

Classifications

• C02F2301/063

  Underpressure, vacuum · CPC title

• C02F2209/42

  Liquid level · CPC title

• B01D21/0084

  Enhancing liquid-particle separation using the flotation principle (flotation in general B03D1/00) · CPC title

• C02F1/20 Primary

  by degassing, i.e. liberation of dissolved gases (degasification of liquids in general B01D19/00; arrangement of degassing apparatus in boiler feed supply F22D) · CPC title

• C02F2103/18

  from the purification of gaseous effluents · CPC title