Abstract
A method for converting a blast furnace plant for synthesis gas utilization includes:
constructing a syngas stove, and constructing a syngas supply system for connecting the syngas stove to a blast furnace;
connecting a first syngas stove to the top-gas supply system, the cold-blast and hot-blast supply systems and operating the first syngas stove for hot blast generation;
disconnecting a first original stove from the top-gas supply system, the cold-blast and hot-blast supply systems; and
converting the first original stove to adapt it for producing syngas. The method includes
connecting the first original stove to the top-gas supply system;
disconnecting the first syngas stove from the cold-blast and hot-blast supply systems, connecting the first original stove and first syngas stove to a gas-combination supply system; and
operating the first original stove and first syngas stove to produce and then supply syngas to the blast furnace via the syngas supply system.
Claims
1. A method for converting a blast furnace plant (1), which initially comprises at least one blast furnace (10, 50), a plurality of original stoves (31-36) adapted for generating hot blast, a top-gas supply system (11, 51) for supplying top gas from at least one blast furnace (10, 50) to each original stove (31-36), a cold-blast supply system (14) for supplying cold blast to each original stove (31-36), a hot-blast supply system (15, 55) for supplying hot blast from each original stove (31-36) to a hot-blast injection system (16, 56), which is adapted to inject gas into at least one blast furnace (10, 50) at a tuyere level (10.1, 50.1), the method comprising: at least partially while operating the original stoves (31-36) to generate hot blast, constructing at least one syngas stove (40, 41), adapted to produce a syngas by reforming a gas combination of a CO.sub.2-containing industrial gas and a hydrocarbon-containing fuel gas, and constructing a syngas supply system (18) adapted for connecting at least one syngas stove (40, 41) to at least one blast furnace (10, 50); connecting a first syngas stove (40) to the top-gas supply system (11, 51), the cold-blast supply system (14) and the hot-blast supply system (15, 55) and operating the first syngas stove (40) for hot blast generation; disconnecting a first original stove (31) from the top-gas supply system (11, 51), the cold-blast supply system (14) and the hot-blast supply system (15, 55); converting the first original stove (31) to adapt it for producing syngas, if necessary by replacing its refractory lining and/or the support of its refractory lining and/or its mechanical components; connecting the first original stove (31) to the top-gas supply system (11, 51); disconnecting the first syngas stove (40) from the cold-blast supply system (14) and the hot-blast supply system (15, 55), connecting the first original stove (31) and the first syngas stove (40) to a gas-combination supply system (19) for supplying the gas combination and via the syngas supply system (18) to at least one blast furnace (10, 50); and operating the first original stove (31) and the first syngas stove (40) to produce syngas and supplying the syngas to the at least one blast furnace (10, 50) via the syngas supply system (18).
2. A method according to claim 1, characterised in that it comprises constructing a syngas injection system (22, 23, 62, 63) that is adapted to inject gas into at least one blast furnace (10, 50) and connecting the syngas supply system (18) to the syngas injection system (22, 23, 62, 63).
3. A method according to claim 2, characterised in that constructing the syngas injection system (22, 23, 62, 63) comprises at least partially converting the hot blast injection system (16, 56) to adapt it for syngas injection.
4. A method according to any of the preceding claims, characterised in that the syngas injection system (22, 23, 62, 63) is adapted to inject gas at the tuyere level (10.1, 50.1) and/or at a shaft level (10.2, 50.2) above the tuyere level (10.1, 50.1).
5. A method according to any of claims 2 to 4, characterised in that the syngas injection system (22, 23, 62, 63) is at least partially constructed during operation of the at least one blast furnace (10, 50).
6. A method according to any of the preceding claims, characterised in that at least one of the following steps is performed during a shutdown of at least one blast furnace (10, 50): connecting a syngas stove (40, 41) to the top-gas supply system (11, 51), the cold-blast supply system (14) and the hot-blast supply system (15, 55); connecting a stove (31-36, 40, 41) to the syngas supply system (18); and connecting the syngas injection system (22, 23, 62, 63) to the at least one blast furnace (10, 50).
7. A method according to any of the preceding claims, characterised in that it comprises the following steps: connecting a second syngas stove (41) to the top-gas supply system (11, 51), the cold-blast supply system (14) and the hot-blast supply system (15, 55); and operating the second syngas stove (41), along with the first syngas stove (40) and the first original stove (31), to produce syngas and supplying the syngas to the at least one blast furnace (10, 50) via the syngas supply system (18).
8. A method according to claim 7, characterised in that the second syngas stove (41) is constructed after operation of the first syngas stove (40) to generate hot blast has started.
9. A method according to any of the preceding claims, characterised in that it comprises, after converting the first original stove (31): connecting the first original stove (31) to the top-gas supply system (11, 51), the cold-blast supply system (14) and the hot-blast supply system (15, 55); disconnecting a second original stove (32) from the top-gas supply system (11, 51), the cold-blast supply system (14) and the hot-blast supply system (15, 55); converting the second original stove (32) to adapt it for producing syngas; at least while the second original stove (32) is being converted, operating the first original stove (31) and the first syngas stove (40) to generate hot blast; disconnecting the first syngas stove (40) and the first original stove (31) from the cold-blast supply system (14) and the hot-blast supply system (15, 55), connecting the first original stove (31), the second original stove (32) and the first syngas stove (40) to the gas-combination supply system (19) and via the syngas supply system (18) to the at least one blast furnace (10, 50); and operating the first original stove (31), the second original stove (32) and the first syngas stove (40) to produce syngas and supplying the syngas to the at least one blast furnace (10, 50) via the syngas supply system (18).
10. A method according to any of the preceding claims, characterised in that it comprises the following steps: disconnecting a third original stove (33) from the top-gas supply system (11, 51), the cold-blast supply system (14) and the hot-blast supply system (15, 55); converting the third original stove (33) to adapt it for producing syngas; connecting the third original stove (33) to the gas-combination supply system (19) and via the syngas supply system (18) to the at least one blast furnace (10, 50); and operating the third original stove (33) to produce syngas and supplying the syngas to the at least one blast furnace (10, 50) via the syngas supply system (18).
11. A method according to any of the preceding claims, characterised in that it comprises constructing a mixing chamber (21) and connecting the mixing chamber (21) to a fuel-gas supply system (20) for supplying the fuel gas and to the gas-combination supply system (19).
12. A method according to claim 11, characterised in that it comprises connecting the top-gas supply system (11, 51) to the mixing chamber (21) and supplying the top gas from a blast furnace (10, 50) as the industrial gas to the mixing chamber (21).
13. A method according to any of the preceding claims, characterised in that all original stoves (31-36) are converted to adapt them for producing syngas.
14. A method according to any of the preceding claims, characterised in that the blast furnace plant (1) comprises a first blast furnace (10) connected to a first group (30) of original stoves (31-36) via a first hot-blast supply system (15) and a first top-gas supply system (11) and a second blast furnace (50) connected to a second group (37) of original stoves (31-36) via a second hot-blast supply system (55) and a second top-gas supply system (51), and the method comprises: connecting the first syngas stove (40) to at least one of the first top-gas supply system (11) and the second top-gas supply system (51); converting all original stoves (31-33) of the first group (30) and connecting them to the gas-combination supply system (19) and the syngas supply system (18); connecting the second hot-blast supply system (55) to the first blast furnace (10); connecting the syngas supply system (18) to the first blast furnace (10) and the second blast furnace (50).
15. A method according to any of the preceding claims, characterised in that after finishing converting, all original stoves (31-33) of the first group (30) are operated to produce syngas while all original stoves (34-36) of the second group (37) are operated to generate hot blast.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Preferred embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:
[0041] FIG. 1 is a schematic view of a first blast furnace plant before application of the inventive method;
[0042] FIGS. 2-4 illustrate different stages of a first embodiment of the inventive method;
[0043] FIGS. 5-9 illustrate different stages of a second embodiment of the inventive method;
[0044] FIG. 10 is a schematic view of a second blast furnace plant before application of the inventive method; and
[0045] FIGS. 11-15 illustrate different stages of a third embodiment of the inventive method.
DETAILED DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 shows a schematic representation of a blast furnace plant 1. It comprises a blast furnace 10, the general operation of which is known in the art and therefore will not be explained here. A hot-blast injection system 16 is disposed at a tuyere level 10.1 of the blast furnace 10. The hot-blast injection system 16 is connected to a hot-blast supply system 15 and to an oxygen supply system 17. The oxygen supply system 17 provides an oxygen-rich gas, which e.g. may have an O.sub.2 concentration of 95 vol % and an N.sub.2 concentration of 5 vol %. As an alternative to the embodiment shown here, the oxygen supply system 17 could be connected to the cold-blast supply system 14, so that oxygen-rich cold blast is supplied to the original stoves 31-33 and oxygen-rich hot blast is supplied to the hot-blast injection system 16. Indeed, generally speaking, if hot blast is used in the blast furnace process, the oxygen supply system feeds oxygen into the cold blast, i.e. upstream of the stoves. If, on the other hand, the blast furnace is operated as a pure oxygen furnace, the supply system feeds oxygen directly to the blast furnace, at tuyere level, as represented in FIG. 1
[0047] Furthermore, an auxiliary fuel like pulverized coal or oil can also be injected with the hot blast, which also applies to the second and third embodiment described below. The hot-blast supply system 15 is connected to three original stoves 31-33, which are configured as hot-blast stoves that receive cold blast from a cold-blast supply system 14 and heat it to generate hot blast. Each of the original stoves 31-33 is connected to a top-gas supply system 11 that receives a top gas (or blast furnace gas) from the top of the blast furnace 10. The recovered top gas may, in the conventional operation of the blast furnace using hot blast, have a N.sub.2 concentration below 50 vol %, a CO and CO.sub.2 concentration of about 23 vol % each and about 6 vol % of H.sub.2. For a blast furnace being operated using syngas, the recovered top gas may have a N.sub.2 concentration below 5 vol %, a CO and CO.sub.2 concentration of about 40 vol % each and about 15 vol % of H.sub.2. The recovered top gas is fed to the top-gas supply system 11 and is cleaned in a gas cleaning plant 13, mostly for removing particulate matter from the gas and possibly condensing a part of the vapour contained in the top gas. The top gas is used to heat the original stoves 31-33.
[0048] FIGS. 2-4 illustrate a first embodiment of an inventive method for converting the blast furnace plant 1 to adapt it for syngas utilisation. As shown in FIG. 2, a first syngas stove 40 is constructed, which has basically the same setup as the original stoves 31-33, that is adapted to support a reforming process, in which a gas combination of a CO.sub.2-containing industrial gas (in this case, the top gas) and a hydrocarbon-containing fuel gas (in this case, coke oven gas, optionally mixed or combined with natural gas) react to produce a syngas (or synthesis gas). The chemical mechanism of the reforming process is not limited within the scope of the disclosure, but it normally comprises at least that the CO.sub.2 content of the industrial gas reacts with the hydrocarbon in the fuel gas, e.g. according to the following reaction: CO.sub.2+CH.sub.4.fwdarw.2 H.sub.2+2 CO. This may also be referred to as dry reforming. Also, the H.sub.2O content of the industrial gas may react with the hydrocarbon in the fuel gas, e.g. according to the following reaction: H.sub.2O+CH.sub.4Δ3 H.sub.2+CO. This may also be referred to as wet reforming. The reforming process normally requires elevated temperatures, e.g. above 800° C. The elevated temperatures and the chemical properties of the substances involved in the reforming process may seriously damage either of the original stoves 31-33 depending on their original configuration/quality. The first syngas stove 40 on the other hand, is adapted from the start to withstand the conditions of the reforming process, which is generally due to a different type of refractory lining and possibly a different type of support for the checker bricks.
[0049] As can also be seen in FIG. 2, a syngas supply system 18 is constructed, which is adapted for connecting the first syngas stove 40 to the blast furnace 10. Also, an upper syngas injection system 22 is constructed at a shaft level 10.2 above the tuyere level 10.1 and a lower syngas injection system 23 is constructed at the tuyere level 10.1. The syngas injection systems 22, 23 each comprise a bustle pipe and injectors that protrude into the blast furnace 10, wherefore the blast furnace 10 needs to be shut down temporarily during the installation of the injectors. Apart from this temporary shutdown, operation of the blast furnace 10 is not interrupted. In the stage shown in FIG. 2, the syngas supply system 18 is neither connected to the syngas injection systems 22, 23 nor to any of the stoves 31-33, 40.
[0050] FIG. 3 shows another stage of the method, where a first original stove 31 is disconnected from the top-gas supply system 11, the cold-blast supply system 14 and the hot-blast supply system 15, while the first syngas stove 40 is connected to these supply systems 11, 14, 15. Again, a temporary shutdown of the blast furnace 10 may be required, which is only for a limited time period, though. The first syngas stove 40 is now operated to generate hot blast, which is possible since the conditions for hot-blast generation are less severe than those for the reforming process. Meanwhile, the first original stove 31 is converted to adapt it for syngas production. This conversion may pertain, if necessary among other, to replacing the refractory lining and/or possibly adapting the support of the refractory lining and/or by replacing/adapting the mechanical components. Also, a second syngas stove 41 is constructed, which is also adapted for syngas production and may be identical to the first syngas stove 40.
[0051] FIG. 4 illustrates a final stage of the method for converting the blast furnace plant 1. The first original stove 31 and the second syngas stove 41 are connected to the top-gas supply system 11, the first original stove 31, the first syngas stove 40 and the second syngas stove 41 are connected to the syngas supply system 18, which is also connected to the syngas injection systems 22, 23. Furthermore, they are connected to a gas-combination supply system 19 that supplies a gas mixture of the top gas and the coke oven gas (and, optionally, the natural gas). A mixing chamber 21 is constructed, to which the gas-combination supply system 19 is connected. Furthermore, the mixing chamber is connected to the top-gas supply system 11, through which it receives the top gas, and to a fuel-gas supply system 20, through which it receives the coke oven gas (and, optionally, the natural gas, as indicated by the dashed arrow). Since the reforming reaction normally requires an elevated pressure, the gas-combination supply system 19 may comprise a compressor. Alternatively, each of the top-gas supply system 11 and the fuel-gas supply system 20 may comprise a compressor, so that the top-gas and the fuel gas are introduced into the mixing chamber 21 under elevated pressure. For sake of simplicity, the compressors are not shown here and in the following.
[0052] The blast furnace plant 1 can resume its operation in a modified form, where a second and third original stove 32, 33 are operated to generate hot blast, which is supplied to the blast furnace 10 at the tuyere level 10.1, while the first original stove 31 and the syngas stove is 40, 41 are operated to produce syngas, which is supplied via the syngas supply system 18 and is injected through the upper syngas injection system 22 at the shaft level 10.2 and through the lower syngas injection system 23 at the tuyere level 10.1.
[0053] While in the embodiment shown in FIGS. 2-4, and upper syngas injection system 22 is constructed at the shaft level 10.2 and additionally a lower syngas injection system 23 is constructed at the tuyere level 10.1, it would be possible to modify this embodiment so that only a single the injection system 22, 23 is constructed either at the tuyere level 10.1 or at the shaft level 10.2 of the blast furnace 10.
[0054] If an auxiliary fuel is injected at the tuyere level 10.1 as mentioned above, this fuel injection can usually continue during and after the conversion. However, in some cases, depending on the amount of syngas produced, auxiliary fuel injection needs to be reduced or even stopped. For instance, if the coke oven gas is supplemented by natural gas, an increased amount of top gas can be converted to syngas, which may make the auxiliary fuel (e.g. pulverized coal) obsolete. This also applies to the second and third embodiment discussed below.
[0055] FIGS. 5-9 illustrate a second embodiment of a method for converting the blast furnace plant 1 shown in FIG. 1. FIG. 5 shows a first stage of the conversion, which is similar to the stage shown in FIG. 2 and insofar will not be described again. In this case, though, only an upper syngas injection system 22 at the shaft level 10.2 is constructed. In a second stage that is shown in FIG. 6, the first syngas stove 40 is connected to the top-gas supply system 11, the cold-blast supply system 14 and the hot-blast supply system 15 and is operated to generate hot blast. Meanwhile, the first original stove 31 is disconnected from the top-gas supply system 11, the cold-blast supply system 14 and the hot-blast supply system 15, whereafter it is converted to adapt it for syngas production.
[0056] In a third stage that is shown in FIG. 7, the first original stove 31, which has been converted, is re-connected to the top-gas supply system 11, the cold-blast supply system 14 and the hot-blast supply system 15 and is operated to generate hot blast. Meanwhile, the second original stove 32 is disconnected from the top-gas supply system 11, the cold-blast supply system 14 and the hot-blast supply system 15, whereafter it is converted to adapt it for syngas production.
[0057] In a fourth stage (shown in FIG. 8), the second original stove 32, which has been converted, is re-connected to the top-gas supply system 11. The mixing chamber 21 is constructed and connected to the top-gas supply system 11 and to the fuel-gas supply system 20. The hot-blast injection system 16 is converted into a lower syngas injection system 23, which comprises adapting the bustle pipe and the tuyere stocks and installing separate lances through which the oxygen-rich gas from the oxygen supply system 17 is injected. Also, the first original stove 31, the second original stove 32 and the first syngas stove 40 are connected to the syngas supply system 18 and via the gas-combination supply system 19 to the mixing chamber 21. The syngas supply system 18 is connected to the upper syngas injection system 22 and to the lower syngas injection system 23. The first and second original stove 31, 32 and the first syngas stove 40 are operated to produce syngas, which is supplied to the blast furnace at the shaft level 10.2 via the syngas supply system 18 and the syngas injection systems 22, 23. Meanwhile, the third original stove 33 is disconnected from the top-gas supply system 11. The cold-blast supply system 14 and the hot-blast supply system 15 are dismantled. The third original stove 33 is converted to adapt it for syngas production.
[0058] FIG. 9 shows a final stage of the conversion process. The third original stove 33 is connected to the top-gas supply system 11, the syngas supply system 18 and the gas-combination supply system 19. Afterwards, it is operated to produce syngas. As can be seen by comparison of FIG. 4 and FIG. 9, the second embodiment completely eliminates hot-blast generation so that only the oxygen-rich gas is injected at the tuyere level 10.1 via the oxygen supply system 17 and the lower syngas injection system 23. All original stoves 31-33 and have been converted and are operated to produce syngas, which is injected via the syngas supply system 18 and the upper syngas injection system 22 at the shaft level 10.2 and the lower syngas injection system 23 at the tuyere level 10.1.
[0059] FIG. 10 shows a second embodiment of a blast furnace plant 1, which basically comprises two blast furnace plants as shown in FIG. 1. It comprises a first blast furnace 10 and a second blast furnace 50. A first hot-blast injection system 16 is disposed at a tuyere level 10.1 of the first blast furnace 10. The first hot-blast injection system 16 is connected to a first hot-blast supply system 15 and to a first oxygen supply system 17. The first hot-blast supply system 15 is connected to a first group 30 of original stoves 31-33, which receive cold blast from a first cold-blast supply system (which is not shown for sake of clarity) and heat it to generate hot blast. Advantageously, the hot blast is oxygen-enriched. Each of the original stoves 31-33 of the first group 30 is connected to a first top-gas supply system 11 that receives a top gas from the first blast furnace 10. Furthermore, a second hot-blast injection system 56 is disposed at a tuyere level 50.1 of the second blast furnace 50. The second hot-blast injection system 56 is connected to a second hot-blast supply system 55 and to a second oxygen supply system 57. The second hot-blast supply system 55 is connected to a second group 37 of original stoves 34-36, which receive cold blast from a second cold-blast supply system (not shown) and heat it to generate hot blast. Each of the original stoves 34-36 is connected to a second top-gas supply system 51 that receives a top gas from the second blast furnace 50.
[0060] FIGS. 11-15 illustrate a third embodiment of the inventive method, by which the blast furnace plant 1 shown in FIG. 10 can be converted. As can also be seen in FIG. 11, a syngas supply system 18 is constructed, which is adapted for connecting the first syngas stove 40 to the first blast furnace 10 and the second blast furnace 50. Also, a first upper syngas injection system 22 is constructed at the shaft level 10.2 of the first blast furnace 10, a first lower syngas injection system 23 is constructed at the tuyere level 10.1 of the first blast furnace 10, a second upper syngas injection system 62 is constructed at the shaft level 50.2 of the second blast furnace 50 and a second lower syngas injection system 63 and is constructed at the tuyere level 50.1 of the second blast furnace 50. In the stage shown in FIG. 11, the syngas supply system 18 is neither connected to any syngas injection system 22, 23, 62, 63 nor to any of the stoves 31-36, 40.
[0061] In a second stage that is shown in FIG. 12, the first syngas stove 40 is connected to the first top-gas supply system 11, the first cold-blast supply system and the first hot-blast supply system 15 and is operated to generate hot blast. Meanwhile, the first original stove 31, which is part of the first group 30, is disconnected from the first top-gas supply system 11, the first cold-blast supply system and the first hot-blast supply system 15, whereafter it is converted to adapt it for syngas production.
[0062] In a third stage that is shown in FIG. 13, the first original stove 31, which has been converted, is re-connected to the first top-gas supply system 11, the first cold-blast supply system and the first hot-blast supply system 15 and is operated to generate hot blast. Meanwhile, the second original stove 32, which is also part of the first group 30, is disconnected from the first top-gas supply system 11, the first cold-blast supply system and the first hot-blast supply system 15, whereafter it is converted to adapt it for syngas production.
[0063] In a fourth stage (shown in FIG. 14), the first original stove 31, which has been converted, is re-connected to the first top-gas supply system 11, the first cold-blast supply system and the first hot-blast supply system 15. Meanwhile, the third original stove 33 is disconnected from the top-gas supply system 11, the first cold-blast supply system and the first hot-blast supply system 15 and is converted to adapt it for syngas production.
[0064] FIG. 15 shows a final stage of the conversion process. The mixing chamber 21 is constructed and connected to the first and second top-gas supply system 11, 51 and the fuel-gas supply system 20. Also, the first original stove 31, the second original stove 32, the third original stove 33 and the first syngas stove 40 are connected to the syngas supply system 18 and via the gas-combination supply system 19 to the mixing chamber 21. The syngas supply system 18 is connected to the first upper and lower syngas injection system 22, 23 and the second upper and lower syngas injection system 62, 63. The first, second and third original stove 31-33 and the first syngas stove 40 are operated to produce syngas, which is supplied to both blast furnaces 10, 50 at the tuyere level 10.1, 50.1 via the syngas supply system 18 and the respective syngas injection system 22, 23, 62, 63. The first cold-blast supply system 14 and the first hot-blast supply system 15 are dismantled. Instead of the first hot-blast supply system 15, the second hot-blast supply system 55 is connected to the first hot-blast injection system 16. All original stoves 31-33 of the first group 30 have been converted and are operated to produce syngas, while all original stoves 34-36 of the second group 37 remain unchanged and are operated to generate hot blast.
[0065] While in the embodiment shown in FIGS. 11-15, there is a respective upper syngas injection system 22, 62 disposed at the shaft level 10.2, 50.2 and additionally a respective lower syngas injection system 23, 63 disposed at the tuyere level 10.1, 50.1, it would be possible to modify this embodiment so that at least one blast furnace 10, 50 only has a single the injection system 22, 23, 62, 63, which would be disposed either at the tuyere level 10.1, 50.1 or at the shaft level 10.2, 50.2 of the respective blast furnace 10, 50.
