REDUCTION OF METAL OXIDES USING GAS STREAM CONTAINING BOTH HYDROCARBON AND HYDROGEN
A gas stream containing both hydrocarbon and hydrogen is separated into a hydrogen-rich fraction and a hydrocarbon-rich fraction. Then at least one sub-quantity of the hydrocarbon-rich fraction is subjected to at least one operation from the group oxidation using technically pure oxygen and reforming using CO 2 and H 2 O. The result is introduced at least as a component of a reduction gas into a reduction unit containing the metal oxides. As a result of the at least one operation, the hydrocarbon content in the reduction gas on entry into the reduction unit is below 12% by volume.
1 - 12 . (canceled)
13 . A method for reducing metal oxides using a coke oven gas, comprising:
separating the coke oven gas into a hydrogen-rich fraction and a hydrocarbon-rich fraction;
subjecting at least a subquantity of the hydrocarbon-rich fraction to at least one operation of the group consisting of oxidation using technically pure oxygen and reforming using CO 2 and H 2 O to obtain at least a component of a reducing gas;
obtaining an auxiliary reducing gas at least in part by mixing top gas that is dedusted and substantially freed from CO 2 , and at least one further gas, including the hydrogen-rich fraction produced by said separating of the coke oven gas;
mixing at least a portion of the component obtained by said subjecting with the auxiliary reducing gas to obtain the reducing gas; and
introducing the reducing gas after said mixing, into a reducing unit containing the metal oxides, where a hydrocarbon content of the reducing gas, as a result of said subjecting and said mixing, is on entry into the reducing unit, less than 12% by volume.
14 . The method as claimed in claim 13 , wherein the hydrocarbon content of the reducing gas, on entry into the reducing unit, is less than 10% by volume.
15 . The method as claimed in claim 14 , wherein the hydrocarbon content of the reducing gas, on entry into the reducing unit, is less than 8% by volume, but greater than 1% by volume.
16 . The method as claimed in claim 15 , wherein the hydrocarbon content of the reducing gas, on entry into the reducing unit, is greater than 2% by volume.
17 . The method as claimed in claim 16 , wherein the hydrocarbon content of the reducing gas, on entry into the reducing unit, is greater than 3% by volume.
18 . The method as claimed in claim 17 , wherein said separating includes at least one operation of the group consisting of pressure-swing adsorption and membrane separation.
19 . The method as claimed in claim 18 , further comprising heating the auxiliary reducing gas in a gas furnace prior to said mixing.
20 . The method as claimed in claim 19 , wherein the gas furnace is operated with a fuel gas which at least in part includes at least one gas of the group consisting of tail gas formed in removal of CO 2 from the top gas, the top gas, the coke oven gas, the hydrogen-rich fraction obtained by said separating of the coke oven gas, and the hydrocarbon-rich fraction obtained by said separating of the coke oven gas.
21 . The method as claimed in claim 13 ,
wherein the reducing unit is a reducing shaft,
wherein said method further comprises introducing a first subquantity of the hydrocarbon-rich fraction directly into the reducing shaft, and
wherein said subjecting subjects a second subquantity of the hydrocarbon-rich fraction to the at least one operation of the group consisting of oxidation using technically pure oxygen and reforming using CO 2 and H 2 O, prior to said mixing.
22 . The method as claimed in claim 21 , wherein the hydrocarbon content of the reducing gas, on entry into the reducing unit, is less than 10% by volume
23 . The method as claimed in claim 22 , wherein the hydrocarbon content of the reducing gas, on entry into the reducing unit, is less than 8% by volume, but greater than 1% by volume.
24 . The method as claimed in claim 21 , further comprising adding at least one gas stream containing at least one of CO 2 and H 2 O to the hydrocarbon-rich fraction before reforming using CO 2 and H 2 O.
25 . A device for reducing metal oxides using a coke oven gas, comprising:
a reducing unit reducing metal oxides;
a separating device separating coke oven gas into a hydrogen-rich fraction and a hydrocarbon-rich fraction;
a feed line, connected to the separating device, supplying the hydrocarbon-rich fraction;
an operation unit, connected to the feed line, carrying out on at least a subquantity of the hydrocarbon-rich fraction an operation of the group consisting of oxidation using technically pure oxygen and reforming using CO 2 and H 2 O, to produce an operation gas stream;
at least one introduction line introducing into said reducing unit a reducing gas including at least one from the group consisting of the hydrocarbon-rich fraction and the operation gas stream produced by the operation unit; and
an auxiliary reducing gas line feeding an auxiliary reducing gas into at least one of the at least one introduction line upstream of the reducing unit, the auxiliary reducing gas including top gas that is dedusted and substantially freed from CO 2 and the hydrogen-rich fraction produced by said separating device, whereby the reducing gas and the auxiliary reducing gas introduced into said reducing unit by the at least one introduction line having a hydrocarbon content that is less than 12% by volume on entry into said reducing unit.
26 . The device as claimed in claim 25 , wherein the hydrocarbon content of the reducing gas and the auxiliary reducing gas, on entry into said reducing unit, is less than 10% by volume.
27 . The device as claimed in claim 26 , wherein the hydrocarbon content of the reducing gas and the auxiliary reducing gas, on entry into said reducing unit, is less than 8% by volume.
28 . The device as claimed in claim 27 , wherein the hydrocarbon content of the reducing gas and the auxiliary reducing gas, on entry into said reducing unit, is greater than 2% by volume.
29 . The device as claimed in claim 28 , wherein the hydrocarbon content of the reducing gas and the auxiliary reducing gas, on entry into said reducing unit, is greater than 3% by volume.
30 . The device as claimed in claim 29 , wherein said separating device includes at least one of a pressure-swing adsorption device and a membrane separation device.
31 . The device as claimed in claim 30 , further comprising gas furnace in said auxiliary reducing gas line upstream of said introduction line.
32 . The device as claimed in claim 31 , wherein said at least one introduction line includes at least two introduction lines of which at least one is not connected to the auxiliary reducing gas line.
33 . The device as claimed in claim 32 , wherein said reducing unit is a reduction shaft.
34 . The device as claimed in claim 32 , wherein said reducing unit is a fluidized-bed cascade.