METHOD AND APPARATUS FOR INCINERATING WASTE

Abstract

Exemplary arrangements relate to a method for incinerating waste on a combustion grate of a furnace and an apparatus for carrying out such a method. Oxygen mixed with carrier gas is supplied to the combustion for incineration as an oxygen and carrier gas mixture. The carrier gas comprises recirculated combustion gas from the furnace and may have a CO.sub.2 concentration of from 10% to 99%.

Claims

1. A method comprising: a) incinerating waste supported on a combustion grate of a furnace via combustion, b) during at least a portion of (a), adding an oxygen and carrier gas mixture to the combustion, wherein the carrier gas comprises recirculated combustion gas produced by the combustion within the furnace with a CO.sub.2 concentration of from 10% to 99%.

2. The method according to claim 1 wherein in (b) the oxygen and carrier gas mixture has an oxygen concentration by volume of from 5% to 40% of the mixture.

3. The method according to claim 1 wherein in (b) the oxygen and carrier gas mixture has an oxygen concentration by volume of from 16% to 40% of the mixture.

4. The method according to claim 1 wherein in (b) the oxygen and carrier gas mixture is added to the combustion in a primary combustion zone of the furnace.

5. The method according to claim 1 wherein in (b) the oxygen and carrier gas mixture is added to the combustion in a secondary combustion zone of the furnace.

6. The method according to claim 1 wherein in (b) the oxygen and carrier gas mixture is added to the combustion in both a primary combustion zone of the furnace and in a secondary combustion zone of the furnace.

7. The method according to claim 1 wherein in (b) the oxygen and carrier gas mixture further comprises air.

8. The method according to claim 1 wherein in (b) the oxygen and carrier gas mixture further comprises atmospheric air.

9. The method according to claim 1, and further comprising: prior to (b), extracting waste combustion gas from the furnace, and treating the waste combustion gas, wherein in (b) the carrier gas comprises the treated waste combustion gas.

10. The method according to claim 1, and further comprising: varying the gas fractions in the oxygen and carrier gas mixture, whereby in (a) incinerating properties are varied.

11. The method according to claim 1 wherein in (a) the combustion grate includes a plurality of disposed combustion zones in which incinerating occurs, wherein in (b) the oxygen and carrier gas mixture is delivered via delivery conduits in a plurality of the combustion zones.

12. The method according to claim 1 wherein in (a) the combustion grate includes a plurality of disposed combustion zones in which incinerating occurs, wherein in (b) the oxygen and carrier gas mixture is delivered in a plurality of the combustion zones, and further comprising: varying the gas fractions of the oxygen and carrier gas mixture, wherein the gas fractions of the oxygen and carrier gas mixture that is delivered in one of the combustion zones in (b) differs from the gas fractions of the oxygen and carrier gas mixture that is delivered in at least one of the other combustion zones in (b).

13. The method according to claim 1 wherein in (a) the combustion grate includes a plurality of disposed combustion zones in which incinerating occurs, wherein in (b) the oxygen and carrier gas mixture is delivered in a plurality of the combustion zones, and further comprising: varying the gas fractions of the oxygen and carrier gas mixture, wherein the gas fractions of the oxygen and carrier gas mixture that is delivered in (b) in each combustion zone of a set including a plurality of zones, differs from the gas fractions of the oxygen and carrier gas mixture that is delivered in (b) in each of the other combustion zones of the set.

14. The method according to claim 1, and further comprising: prior to (b), delivering waste gas from the furnace to a separating device that separates CO.sub.2 from the waste gas, wherein in (b) the recirculated combustion gas includes gas separated by the separating device.

15. The method according to claim 1, and further comprising: during at least a portion of (a) additionally adding separately at least one of air and oxygen to the combustion.

16. The method according to claim 1 wherein in (b) the mixture of oxygen and carrier gas is added both above and below the combustion grate.

17. The method according to claim 1, and further comprising: during at least a portion of (a) separately adding air to the combustion, both above and below the combustion grate.

18. The method according to claim 1, and further comprising: during at least a portion of (a) separately adding oxygen to the combustion, both above and below the combustion grate.

19. A method comprising: a) carrying out combustion within an interior area of a furnace to incinerate waste, b) during at least a portion of (a) adding a mixture comprised of oxygen and carrier gas to the interior area of the furnace, wherein the carrier gas comprises recirculated combustion gas produced by the combustion within furnace with a CO.sub.2 concentration of from 10% to 99%.

20. Apparatus comprising: a furnace, wherein the furnace includes an internal combustion grate, wherein the furnace is configured to incinerate waste supported on the combustion grate via combustion in a combustion zone, a separating device, wherein the separating device is operative to receive combustion gas produced by the furnace during combustion, and separate CO.sub.2 from the combustion gas produced by the furnace, at least one conduit operative to deliver a mixture of oxygen and the CO.sub.2 separated from the combustion gas into the combustion zone.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1 is a schematic cross-sectional representation of components of an exemplary incineration plant.

[0025] FIG. 2 is a schematic diagram of an exemplary incineration plant and the material flows.

DETAILED DESCRIPTION

[0026] The exemplary incineration furnace shown in FIG. 1 has a combustion grate 2, to which primary air feed lines 3, 4, 5 and 6 lead. These primary air feed lines 3, 4, 5 and 6 lead to outlets in individual combustion zones 7, 8, 9 and 10 of the combustion grate 2. Besides the primary air feed lines 3, 4, 5 and 6, recirculation gas feed lines 11, 12, 13 and 14 are located to deliver gas under the combustion grate 2. The primary air feed lines 3, 4, 5 and 6 have a port 15 for delivery of primary air, the recirculation gas feed lines 11, 12, 13, and 14 have a port 16 for delivery of recirculation gas, and the oxygen feed lines 17, 18, 19 and 20 have a port 21 for delivery of oxygen.

[0027] Valves 22, 23 and 24 (numbered for exemplary purposes only) in the primary air feed lines 3, 4, 5 and 6, in the recirculation gas feed lines 11, 12, 13 and 14 and in the oxygen feed lines 17, 18, 19 and 20 make it possible to supply different gases and mixtures thereof to the combustion grate 2, tuned highly selectively to the individual combustion zones 7, 8, 9 and 10.

[0028] Above the exemplary waste supporting combustion grate 2, the waste gas flue 25 is furnished with secondary air feed lines 26, 27, 28 and 29, which have a separate or common port 30, 31 for delivery of air and/or recirculation gas. In the exemplary arrangement each secondary air feed line includes a valve 32, 33, 34 and 35 to allow the supply of air and/or recirculation gas to be adjusted or regulated. The air and/or the recirculation gas are fed in controlled manner via valves 32, 33, 34 and 35 to secondary air nozzles 36, 37, 38 and 39, via which the secondary air reaches the waste gas flue 25. Oxygen feed lines 40, 41, 42 and 43 are arranged between each of the valves 32, 33, 34 and 35 and the secondary air nozzles 36, 37, 38 and 39, and each feed line has a port 44, 45 for delivery of oxygen.

[0029] In this way, secondary air in the waste gas flue 25 can also be supplied as air and/or recirculation gas via the nozzles 36, 37, 38 and 39. Numerous different combinations and amounts of the mixture of oxygen and carrier gas, oxygen, air and recirculated combustion gas may be delivered via outlets from conduits above and below the exemplary combustion grate.

[0030] When the exemplary furnace 1 is in use, waste 46 is incinerated supported on the combustion grate 2, via combustion, and during the incineration oxygen is forwarded to the combustion grate 2 via lines 17, 18, 19 and 20 and oxygen is forwarded to the waste gas flue 25 via lines 40, 41, 42 and 43. This oxygen is supplied together with recirculation gas, which can be added via ports 16, 30 and 31.

[0031] FIG. 2 is a schematic representation of a method according to an exemplary arrangement. Fuel 50 is supplied to the furnace 1, and the flue gases 51 are forwarded to heat recovery 52 and from there to waste gas purification 53. From waste gas purification 53, the waste gas 51 passes to post-treatment in a separate device 54, in which CO.sub.2 is separated. After the post-treatment 54, at least a portion of the waste gas is returned as recirculated combustion gas to the furnace 1. Waste gas streams 55 and 56 from waste gas purification 53 or from heat recovery 52 may be fed to this waste gas stream from the post-processing separate device 54 for firing 51. A feed line 57 for air and a feed line 58 for oxygen are also provided.

[0032] Thus the exemplary arrangements achieve improved operation, eliminate difficulties encountered in the use of prior devices, systems and methods, and attain the useful results described herein.

[0033] In the foregoing description, certain terms have been used for brevity, clarity and understanding. However no unnecessary limitations are to be implied therefrom because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover the descriptions and illustrations herein are by way of examples and the new and useful features are not limited to the exact features that have been shown and described.

[0034] Having described features, discoveries and principles of the exemplary arrangements, the manner in which they are constructed and operated, and the advantages and useful results attained, the new and useful features, devices, elements, arrangements, parts, combinations, systems, equipment, operations, methods, processes and relationships are set forth in the appended claims.