METHOD FOR BLOWING SUBSTITUTE REDUCING AGENTS INTO A BLAST FURNACE

Abstract

The present invention relates to a method for pneumatically blowing a powdery substitute reducing agent in a dense flow process, by means of a transport gas, into a gasification reactor, or via a tuyere into a blast furnace. The substitute reducing agent is gasified in a gasification reaction. The transport gas comprises a fuel gas, the constituents of which or the oxidation constituents of which are at least partly involved in the gasification reaction.

Claims

1-17. (canceled)

18. A method for pneumatically blowing a powdery substitute reducing agent in a dense flow process, in which a flow density of the powdery substitute reducing agent is 60% or more of the packing density in the bulk state, by means of a transport gas, into a reactor or via a tuyere into a blast furnace, so that the substitute reducing agent is gasified in a gasification reaction, wherein the transport gas comprises a fuel gas, which is carbon monoxide, hydrogen, water vapor, oxygen, hydrocarbon, furnace gas, natural gas, coke gas, converter gas, another blast furnace gas, or a mixture thereof.

19. A method for pneumatically blowing a powdery substitute reducing agent in a dense flow process, in which a flow density of the powdery substitute reducing agent is 60% or more of the packing density in the bulk state, by means of a transport gas, into a reactor, or via a tuyere into a blast furnace, so that the substitute reducing agent is gasified in a gasification reaction, wherein the transport gas consists of a fuel gas, the components of which or their oxidation components at least partially participate in the gasification reaction, and of another gas or gas mixture than the fuel gas.

20. A method according to claim 18, wherein the transport gas consists to at least 2 w. %, preferably at least 5 w. %, preferably at least 10 w. % of the fuel gas, and wherein the transport gas in particular consists to maximum 90 w. %, preferably maximum 50 w. %, further preferably maximum 25 w. %, further preferably maximum 20 w. % of the fuel gas.

21. A method according to claim 19, wherein the other gas comprises nitrogen.

22. A method according to claim 18, wherein the substitute reducing agent is injected with the transport gas through a first injection lance, and wherein the first injection lance protrudes into the tuyere.

23. A method according to claim 22, wherein in addition to the substitute reducing agent and transport gas, oxygen is also supplied to the reactor through the first injection lance and is combined with the substitute reducing agent and transport gas in an opening region of the first injection lance, wherein the first injection lance has an inner first pipe and a second pipe arranged around this, whereby a ring gap surrounding the first pipe is formed between the first and second pipes, and wherein the substitute reducing agent and the transport gas are conducted through the first pipe and the oxygen is conducted through the ring gap.

24. A method according to claim 22, wherein the first injection lance is a single pipe and wherein oxygen is conducted through a second injection lance into the reactor via the tuyere into the blast furnace.

25. A method for pneumatically blowing a powdery substitute reducing agent in a dense flow process, in which a flow density of the powdery substitute reducing agent is 60% or more of the packing density in the bulk state, by means of a transport gas, into a reactor or via a tuyere into a blast furnace, so that the substitute reducing agent is gasified in a gasification reaction, wherein the substitute reducing agent with the transport gas is blown in through a first injection lance, wherein in addition to the substitute reducing agent and transport gas, oxygen is also supplied to the reactor through the first injection lance and is combined with the substitute reducing agent and transport gas in an opening region of the first injection lance, wherein the first injection lance has an inner first pipe and a second pipe arranged around this, whereby a ring gap surrounding the first pipe is formed between the first and second pipes, wherein the substitute reducing agent and the transport gas are conducted through the first pipe and the oxygen is conducted through the ring gap, and wherein the transport gas comprises a fuel gas, the components of which or their oxidation components participate at least partially in the gasification reaction.

26. A method according to claim 23, wherein at least one substitute reducing agent with the fuel gas and the oxygen is conducted through at least one first injection lance and at least one second injection lance into the reactor via the tuyere.

27. A method according to claim 23, wherein at least one of the outlet speed and the quantity of oxygen is adjusted depending on the reaction.

28. A method according to claim 18, wherein a mixing of the substitute reducing agent and transport gas with oxygen is promoted by an eddy structure.

29. A method according to claim 18, wherein at least one of a ratio between the substitute reducing agent and fuel gas, an outlet speed, and an injection quantity of the substitute reducing agent and transport gas is adjusted depending on the reaction.

30. A method according to claim 18, wherein at least one of the transport gas, the substitute reducing agent, and the oxygen has a temperature of between 100° C. and 950° C.

31. A method according to claim 19, wherein the fuel gas consists of carbon monoxide, carbon dioxide, hydrogen, water vapor, oxygen, hydrocarbon, or a mixture thereof.

32. A device for performance of the method according to claim 18, comprising an injection lance for blowing the substitute reducing agent into the reactor or into the tuyere of the blast furnace, a vessel for receiving at least one of the transport gas and the substitute reducing agent, and a transport line for supplying the substitute reducing agent from the vessel to the injection lance, wherein the device furthermore comprises a fuel gas supply via which a fuel gas can be supplied to the transport gas upstream of the injection lance.

33. A device according to claim 32, wherein the fuel gas supply is arranged on the transport line, wherein a distance along the transport line from the fuel gas supply to the injection lance is less than the distance along the transport line to the vessel.

34. A device according to claim 32, wherein the fuel gas supply is arranged upstream of the injection lance and downstream of a distribution device.

35. A device according to claim 31, wherein the fuel gas consists of furnace gas, natural gas, coke gas, converter gas, another blast furnace gas, or a mixture thereof.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0062] FIGS. 1a to 1c depict diagrammatically a preferred injection plant for a blast furnace and some details of such an injection plant.

[0063] FIG. 2 shows a further preferred injection plant which has a static distributor.

[0064] FIG. 3 shows a further preferred injection plant which has a distribution vessel instead of a static distributor.

WAYS OF IMPLEMENTING THE INVENTION

[0065] The same or corresponding elements are identified in the description of the figures below by the same reference numerals and are only described once. In principle, features described in connection with one embodiment may also be implemented in another embodiment. This applies in particular to the arrangement and configuration of elements influencing flow, such as valves, chokes or distributors, and for the configuration of the mechanism for injecting the substitute reducing agent into the tuyere.

[0066] FIG. 1a is a diagrammatic depiction of a preferred injection plant 100. The injection plant 100 comprises a tuyere 7 via which the hot blast from a blast ring 8 can be injected into a blast furnace. Arranged in the tuyere 7 is an injection lance 6, preferably configured as a coaxial dust and gas injection lance, through which at the same time a first flow of substitute reducing agent and transport gas containing a fuel gas, and a second flow comprising oxygen or an oxygen-containing gas, can be supplied to the hot blast in the dense flow process.

[0067] In the embodiment depicted, the injection lance 6 is connected to an individual transport line 5 through which the substitute reducing agent can be transported from an injection vessel 3 via a fluidization vessel 4 to the injection lance 6. Preferably, a blast furnace plant may comprise several injection lances 6, individual transport lines 5 and in some cases also fluidization vessels 4, in order to inject as large a quantity as possible of substitute reducing agent into the blast furnace, distributed as evenly as possible.

[0068] Upstream of the injection vessel 3 in the depiction in FIG. 1a is a pressure lock 2, through which the pressurized injection vessel 3 is supplied optionally with substitute reducing agent which can then be topped up. For example, the pressure lock 2 may be filled under ambient pressure with coal dust or another substitute reducing agent, the pressure lock 2 may then be brought to the delivery pressure of the injection vessel 3, and then the substitute reducing agent introduced into the injection vessel 3. To control this, in FIG. 1a a shut-off valve 1 is arranged upstream and downstream of the pressure lock 2, wherein the valves mentioned as examples in the present description, and other flow-influencing elements may also be supplemented, modified, replaced and partly also omitted.

[0069] FIG. 1a shows at points marked “A” locations at which for example transport gas and/or fuel gas may be introduced into the system. At the point marked “B”, upstream of the first shut-off valve 1 in the embodiment outlined in FIG. 1a, the substitute reducing agent or fuel may be introduced into the system.

[0070] In the region of the points marked “A” of the individual transport line 5, preferably a fuel gas may be added to the transport gas so that the transport gas consists for example to at least 2 w. % of fuel gas, the components of which or their oxidation components participate at least partially in a gasification reaction of the substitute reducing agent in the tuyere 7 and the blast furnace. The fuel gas may be introduced into the system preferably at one or both of the points marked “A” on the individual transport line 5, so that the transport gas downstream of this point consists to at least 2 w. % of fuel gas and the remainder of another gas or gas mixture, and hence leads to a particularly efficient injection of the substitute reducing agent in relation to its subsequent gasification.

[0071] At the point marked “C” directly upstream of the injection lance 6, in the embodiment shown in FIG. 1a, it is provided that the injection lance 6 is supplied with oxygen. In the embodiment shown in FIG. 1a, the injection lance 6 is preferably configured such that the substitute reducing agent with the transport gas, which comprises at least 2 w. % fuel gas, is introduced into the tuyere 7 through a central pipe which is surrounded by a ring gap, through which oxygen or an oxygen-containing gas is injected into the tuyere 7 as a casing flow of the transport gas.

[0072] Such a configuration of the injection lance 6 leads to a particularly efficient gasification reaction, which thus proceeds particularly quickly and begins particularly early, and hence allows the addition of a particularly large quantity of substitute reducing agent and the saving of a particularly large quantity of high-quality and expensive blast furnace coke.

[0073] FIG. 1b shows an alternative embodiment of the injection mechanism which comprises a single dust injection lance 16 and a single gas injection lance 17. The substitute reducing agent with transport gas is injected into the tuyere 7 via the dust injection lance 16, and the oxygen is injected via the gas injection lance 17.

[0074] Preferably, immediately before the single dust injection lance 16, the fuel gas is supplied to the substitute reducing agent and transport gas at the point marked “A”. However it is also possible that the fuel gas is already contained in the supply system and the substitute reducing agent is conveyed by the transport gas, which already partially or completely contains the fuel gas, substantially further upstream of the point shown in FIG. 1b.

[0075] FIG. 1c illustrates a further preferred embodiment in which only a single dust injection lance 16 is provided, while no guided injection of oxygen is provided. Oxygen may here be supplied by a corresponding enrichment of the hot blast via the blast ring 8, or taken from the hot blast without separate enrichment, in order to perform the gasification reaction of the substitute reducing agent.

[0076] FIG. 2 shows an alternative embodiment of an injection plant 200.

[0077] In contrast to the injection plant in FIG. 1a, FIG. 2 shows an injection plant 200 without a separate pressure lock. Such a separate pressure lock may however also be provided in the embodiment according to FIG. 2. In the injection system 200, in particular two separate injection vessels 3 are provided, wherein more than two injection vessels 3 may also be present. From the injection vessels 3, the substitute reducing agent and transport gas enter a pipe system via a respective fluidization vessel 4. as in the embodiment in FIG. 1a.

[0078] The injection plant 200 comprises for example two collective transport lines 9. In principle, a single collective transport line 9 may also be provided, or more than two collective transport lines 9. Through the collective transport lines 9, the substitute reducing agent and transport gas from the fluidization vessel 4 reach a static distributor 10, in which they are distributed over several individual transport lines 5. The individual transport lines 5 then each lead to an injection lance 6, wherein this injection plant 200 too may be configured and modified as described in connection with FIG. 1.

[0079] Preferably, the individual transport lines 5 each comprise a choke 20 in order to be able to adjust reliably the distribution of the substitute reducing agent to be injected. Alternatively and additionally, the individual transport lines 5 may also be equipped with control valves.

[0080] Particularly preferably, the fuel gas is added to the transport gas at the points marked “A” on the individual transport lines 5. In principle however, it is also possible that fuel gas is supplied upstream of these points, namely for example in the region of the collective transport lines 9, or directly to the injection vessels 3. For safety reasons however, it is preferred that the fuel gas is supplied to the transport gas as far downstream as possible. In particular, in this way the risk of explosion of the injection plant can be kept very low.

[0081] FIG. 3 shows a further preferred embodiment of an injection plant 300, wherein the injection plant 300 according to FIG. 3 has three intermediate transport vessels 11 instead of the injection vessels 3 of the two embodiments described above.

[0082] From the intermediate transport vessels 11, the substitute reducing agent and transport gas reach a distribution vessel 12 via a collective transport line 9. From the distribution vessel 12, via a fluidization vessel 4 in the same way as in the embodiments described above, substitute reducing agent with transport gas may be conducted via an individual transport line 5 to the injection lance 6 for injection into the tuyere 7. Instead of the injection lance 6, in this embodiment too, other mechanisms may be used for blowing the substitute reducing agent into the tuyere 7.

[0083] From the distribution vessel 12, via a gas control valve 14 mounted downstream of a filter 13, surplus gas may be discharged to the environment. Also, the third preferred embodiment of the injection plant 300 contains some valves, in particular shut-off valves 1 and dust control valves 15, in order to be able to control the flow of the substitute reducing agent and transport gas reliably. For the sake of completeness, it is stated that such valves, in particular the dust control valves 15, may be provided on the individual transport lines 5 and also on the collective transport line 9 or lines 9. In connection with the present invention, no particular requirements are imposed on the arrangement and configuration of valves, vessels and similar components, nor on the configuration of the gas transport system, but these result from the professional design of the injection plant as known in principle.

[0084] In the embodiment shown in FIG. 3, the fuel gas is also supplied to the transport gas particularly preferably at the points marked “A” on the individual transport line 5. In the same way as in the embodiments described above according to FIGS. 1 and 2, it is however also possible to acid the fuel gas to the system at other points. For example, in FIG. 3, various points are marked “A” at which the fuel gas may be added to the system.

[0085] The embodiments described above show three exemplary possibilities for how the method according to the invention may be implemented in terms of the plant. The invention is not however restricted to these particular embodiments of an injection plant but may also be used in different types of device.

[0086] In particular, the embodiment of the injection lance(s) may be selected individually for each injection plant and combined, wherein the exemplary embodiments illustrated in connection with FIG. 1 may evidently also be used in the embodiments shown in FIGS. 2 and 3 and may be combined arbitrarily.

[0087] Using the injection plants described above, the method according to the invention may be applied well. In this way it is possible to achieve substantial savings in fuel costs in the blast furnace process or gasification reactors, in that a larger quantity of substitute reducing agent is injected into the blast furnace or reactor than is possible with the methods according to the prior art, because the gasification reaction according to the invention can proceed more quickly and begin earlier.