CA1050265A - Apparatus for injection of hot reducing gas into a shaft - Google Patents
Apparatus for injection of hot reducing gas into a shaftInfo
- Publication number
- CA1050265A CA1050265A CA223,263A CA223263A CA1050265A CA 1050265 A CA1050265 A CA 1050265A CA 223263 A CA223263 A CA 223263A CA 1050265 A CA1050265 A CA 1050265A
- Authority
- CA
- Canada
- Prior art keywords
- gas
- plasma
- furnace
- injection tube
- tuyere
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/001—Injecting additional fuel or reducing agents
- C21B5/002—Heated electrically (plasma)
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/001—Injecting additional fuel or reducing agents
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
- Manufacture Of Iron (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Blast Furnaces (AREA)
- Furnace Details (AREA)
- Plasma Technology (AREA)
Abstract
ABSTRACT
Reducing gas is injected into a shaft furnace by means of a gas supply duct, an injection tube, and a tuyere co-axial with the injection tube. The injection tube comprises a plasma furnace co-axial with and adjacent to the tuyere. While the reducing gas is being injected into the shaft furnace a plasma is generated in the plasma furnace to heat the reducing gas.
Reducing gas is injected into a shaft furnace by means of a gas supply duct, an injection tube, and a tuyere co-axial with the injection tube. The injection tube comprises a plasma furnace co-axial with and adjacent to the tuyere. While the reducing gas is being injected into the shaft furnace a plasma is generated in the plasma furnace to heat the reducing gas.
Description
The present invention relates to apparatus for inject-ing hot reducing gas into a shaft furnace, particularly into the zone at the top of the hearth of a blast furnace, preferably at the level of the main tuyeres, and to a method of operation of this apparatus.
It is known to replace a part of the coke in the charge of an iron blast furnace and a part of the hot blast blown in through the main tuyeres by a certain amount of hot reducing gas injected into the top of the hearth of a blast furnace. The reducing gas is injected at a high temperature and mainly consists of CO and H2.
This replacement is particularly recommended for decreasing the consumption of coke, an expensive and sometimes not readily available fuel. It would be possible to meet the whole requirement of heat and reducing gas in this way. In this case, apart from its function of carburizing of the metal, coke would only play the mechanical role of a refractory sup-t port carrying the solid burden and allowing the metal to be decanted from the slag.
As is known, many processes ~or producing reducing gas are known at present, for example catalytic oxidation by means of water vapour or partial oxidation (reforming) by oxygen, applied to gaseous or liquid hydrocarbons.
Moreover, in view of diversifying the energy sources employed in siderurgy, we have already suggested the production of reducing gases from a liquid or gaseous hydrocarbon or a solid carbonaceous material such as coal by using the throat gas as oxidizer.
In any case, the reducing gases obtained are heated to a temperature of 1700C to 2500C to be injected into the top of the hearth of the blast furnace. These high temperatures can be reached in several ways; however, excellent results have i: ~
~OSOZ6S
been obtained, according to a process also suggested by the Applicants, by heating this gas in a plasma medium. This pro-cess is particularly advantageous in view of a prospective - -decrease of the relative cost of electrical energy as a result of the production of electrical energy through nuclear power.
The present invention provides apparatus for injecting hot reducing gas into a shaft furnace, comprising a gas supply duct, a tuyere directed into the interior of the shaft furnace, and an injection tube communicating between the supply duct and the tuyere and being co-axial with the tuyere, in which tne injection tube comprises at least one plasma furnace co-axial with and adjacent to the tuyere.
The invention also provides a method of operating a shaft furnace, comprising: injecting reducing gas into the furnace through a supply duct, an injection tube, and a tuyere co-axial with the injection tube, the injection tube comprising at least one plasma furnace through which the reducing gas passes, said at least one plasma furnace being co-axial with and adjacent to the tuyere; and simultaneously generating a plasma in the at least one plasma furnace.
In this way, the reducing gas, which is heated or produced and heated by the plasma, can be injected into a shaft furnace and particularly into the top of the hearth of a blast furnace by means of tuyeres located approximately at the level of the main blast tuyeres or even by means of the main blast tuyeres themselves.
The injection tube (which, when operating convention-ally serves to supply the tuyere with hot air) may be either ~holly or only partly constituted by the plasma furnace or plasma furnaces (e.g. two arranged in series).
Pre~erably, the injection tube is provided with a cover or hood designed to protect it against leaking water and lOSOZ65 to form an acoustic screen.
In a preferred embodiment, a pilot plasma-generating gas is injected into the plasma furnace or furnaces by one or more arc plasma torches, the gas being an inert gas, such as argon or (preferably) nitrogen, the latter being a by-product easily available and of low cost in siderurgy.
Alternatively, the pilot gas may be industrially pure hydrogen.
Another alternative for the pilot plasma generating gas is "impure" reducing gas which may include, apart from major quantities hydrogen, CO, and nitrogen, minor quantities of H2O
and CO2 The gas to be injected into the shaft furnace and to be supplied to the plasma furnace(s) is advantageously pre-heated by convéntional means, that is not by plasma means, to a temper- _ ature of 900C to 1400C.
In the case where there are two plasma furnaces arranged in series, the reducing gas can be heated in two stages, the downstream furnace being designed to provide an injection temperature from 1700C to 2500C.
,~ Also in the case where there are two plasma furnaces arranged in series, these furnaces may be fed with gas to be ` reformed ana oxidising gas, one of the furnaces causing reform-ing and the other effecting heating, for example.
When during operation the injection of hot reducing gases into the top of the hearth of the blast furnace has to be terminated, the plasma torches are advantageously kept in an atmosphere of an inert gas under pressure (such as nitrogen) to protect them by preventing corrosive gases from entering.
Moreover, in order t~ stabilize the position of the plasma within the injection tube, the pressure in the blast furnace is measured and the intensity of the electric current to the plasma furnace(s) is adjusted as a function of the varia-tions in pressure detected so as to maintain constant the con-sumed electric power.
In view of the high speed of the gases flowing through the plasma furnace(s), the stability of the electric arcs is preferably assisted by seeding the pilot gases and by adding to them thoroughly dispersed compounds capable of being easily ionized such as alkali metal or alkaline-earth metal compounds, for example halides, preferably CaC12.
The invention will be described further, by way of .
example only, with reference to the accompanying drawings, in which:
Figure 1 illustrates, in vertical section, the arrange- .
ment of a main tuyere in a blast furnace, certain details shown in Figure 2, being omitted for clarity; and Figure 2 is a cross-sectional view of a detail of the :, .
tuyere arrangement of Figure 1 on an enlarged scale.
In Figure 1, only part of the blast furnace is illus-trated, its outer metal casing 1 and its refractory lining 2 being shown.
The conventional circuit of the hot blast usually injected into the top of the hearth of the blast furnace com-prises the hot blast circulating duct 3 and a connecting duct , 4 (kno~n as the goose neck) which connects the duct 3 to an injection tube 5, opening into the tuyere proper 6. Also shown is the water-cooled tuyere-casing 7 and the holder 8.
Figure 2 shows the injection tube 5, made in two parts, one o$ which comprises a cylindrical plasma furnace 9 adjacent to the tuyere proper 6. The tuyere proper 6 and the two parts of the inlet tube 5 are coaxial, having a common longitudinal axis 10-11. The plasma furnace 9 is a three-phase plasma furnace whose neutral point is arranged on the axis 10-11.
- - 1050Z~S
The cylindrical plasma furnace 9 has a refractory lin:ing 12 and a jaeket 13 for water eireulation 14. The furn-aee 9 has three radial plasma torehes 15 spaeed at 120 from one another, their axes interseeting at a point on the longi-tud:inal axis 10-11.
~' .
It is known to replace a part of the coke in the charge of an iron blast furnace and a part of the hot blast blown in through the main tuyeres by a certain amount of hot reducing gas injected into the top of the hearth of a blast furnace. The reducing gas is injected at a high temperature and mainly consists of CO and H2.
This replacement is particularly recommended for decreasing the consumption of coke, an expensive and sometimes not readily available fuel. It would be possible to meet the whole requirement of heat and reducing gas in this way. In this case, apart from its function of carburizing of the metal, coke would only play the mechanical role of a refractory sup-t port carrying the solid burden and allowing the metal to be decanted from the slag.
As is known, many processes ~or producing reducing gas are known at present, for example catalytic oxidation by means of water vapour or partial oxidation (reforming) by oxygen, applied to gaseous or liquid hydrocarbons.
Moreover, in view of diversifying the energy sources employed in siderurgy, we have already suggested the production of reducing gases from a liquid or gaseous hydrocarbon or a solid carbonaceous material such as coal by using the throat gas as oxidizer.
In any case, the reducing gases obtained are heated to a temperature of 1700C to 2500C to be injected into the top of the hearth of the blast furnace. These high temperatures can be reached in several ways; however, excellent results have i: ~
~OSOZ6S
been obtained, according to a process also suggested by the Applicants, by heating this gas in a plasma medium. This pro-cess is particularly advantageous in view of a prospective - -decrease of the relative cost of electrical energy as a result of the production of electrical energy through nuclear power.
The present invention provides apparatus for injecting hot reducing gas into a shaft furnace, comprising a gas supply duct, a tuyere directed into the interior of the shaft furnace, and an injection tube communicating between the supply duct and the tuyere and being co-axial with the tuyere, in which tne injection tube comprises at least one plasma furnace co-axial with and adjacent to the tuyere.
The invention also provides a method of operating a shaft furnace, comprising: injecting reducing gas into the furnace through a supply duct, an injection tube, and a tuyere co-axial with the injection tube, the injection tube comprising at least one plasma furnace through which the reducing gas passes, said at least one plasma furnace being co-axial with and adjacent to the tuyere; and simultaneously generating a plasma in the at least one plasma furnace.
In this way, the reducing gas, which is heated or produced and heated by the plasma, can be injected into a shaft furnace and particularly into the top of the hearth of a blast furnace by means of tuyeres located approximately at the level of the main blast tuyeres or even by means of the main blast tuyeres themselves.
The injection tube (which, when operating convention-ally serves to supply the tuyere with hot air) may be either ~holly or only partly constituted by the plasma furnace or plasma furnaces (e.g. two arranged in series).
Pre~erably, the injection tube is provided with a cover or hood designed to protect it against leaking water and lOSOZ65 to form an acoustic screen.
In a preferred embodiment, a pilot plasma-generating gas is injected into the plasma furnace or furnaces by one or more arc plasma torches, the gas being an inert gas, such as argon or (preferably) nitrogen, the latter being a by-product easily available and of low cost in siderurgy.
Alternatively, the pilot gas may be industrially pure hydrogen.
Another alternative for the pilot plasma generating gas is "impure" reducing gas which may include, apart from major quantities hydrogen, CO, and nitrogen, minor quantities of H2O
and CO2 The gas to be injected into the shaft furnace and to be supplied to the plasma furnace(s) is advantageously pre-heated by convéntional means, that is not by plasma means, to a temper- _ ature of 900C to 1400C.
In the case where there are two plasma furnaces arranged in series, the reducing gas can be heated in two stages, the downstream furnace being designed to provide an injection temperature from 1700C to 2500C.
,~ Also in the case where there are two plasma furnaces arranged in series, these furnaces may be fed with gas to be ` reformed ana oxidising gas, one of the furnaces causing reform-ing and the other effecting heating, for example.
When during operation the injection of hot reducing gases into the top of the hearth of the blast furnace has to be terminated, the plasma torches are advantageously kept in an atmosphere of an inert gas under pressure (such as nitrogen) to protect them by preventing corrosive gases from entering.
Moreover, in order t~ stabilize the position of the plasma within the injection tube, the pressure in the blast furnace is measured and the intensity of the electric current to the plasma furnace(s) is adjusted as a function of the varia-tions in pressure detected so as to maintain constant the con-sumed electric power.
In view of the high speed of the gases flowing through the plasma furnace(s), the stability of the electric arcs is preferably assisted by seeding the pilot gases and by adding to them thoroughly dispersed compounds capable of being easily ionized such as alkali metal or alkaline-earth metal compounds, for example halides, preferably CaC12.
The invention will be described further, by way of .
example only, with reference to the accompanying drawings, in which:
Figure 1 illustrates, in vertical section, the arrange- .
ment of a main tuyere in a blast furnace, certain details shown in Figure 2, being omitted for clarity; and Figure 2 is a cross-sectional view of a detail of the :, .
tuyere arrangement of Figure 1 on an enlarged scale.
In Figure 1, only part of the blast furnace is illus-trated, its outer metal casing 1 and its refractory lining 2 being shown.
The conventional circuit of the hot blast usually injected into the top of the hearth of the blast furnace com-prises the hot blast circulating duct 3 and a connecting duct , 4 (kno~n as the goose neck) which connects the duct 3 to an injection tube 5, opening into the tuyere proper 6. Also shown is the water-cooled tuyere-casing 7 and the holder 8.
Figure 2 shows the injection tube 5, made in two parts, one o$ which comprises a cylindrical plasma furnace 9 adjacent to the tuyere proper 6. The tuyere proper 6 and the two parts of the inlet tube 5 are coaxial, having a common longitudinal axis 10-11. The plasma furnace 9 is a three-phase plasma furnace whose neutral point is arranged on the axis 10-11.
- - 1050Z~S
The cylindrical plasma furnace 9 has a refractory lin:ing 12 and a jaeket 13 for water eireulation 14. The furn-aee 9 has three radial plasma torehes 15 spaeed at 120 from one another, their axes interseeting at a point on the longi-tud:inal axis 10-11.
~' .
Claims (18)
1. Apparatus for injecting hot reducing gas into a blast furnace, comprising a gas supply duct arranged to supply a reducing gas or a gas consisting of a mixture of hydrocarbon gas to be reformed and an oxidizing gas, a tuyere directed into the blast furnace, an injection tube communicating between the supply duct and the tuyere and being coaxial with the tuyere, the injection tube comprising at least one plasma furnace, the at least one plasma furnace being coaxial with and adjacent to the tuyere, and means for supplying a plasma to the furnace to heat the said gas.
2. Apparatus as claimed in claim 1, in which the injection tube is only partly constituted by the at least one plasma furnace.
3. Apparatus as claimed in claim 1, in which the injection tube has two plasma furnaces in series.
4. Apparatus as claimed in claim 1, including a hood covering the injection tube to protect it against leaking water and to form an acoustic screen.
5. A method of injecting hot reducing gas into a blast furnace, comprising: supplying reducing gas or a gas consisting of a mixture of hydrocarbon gas to be reformed and oxidizing gas through a supply duct to an injection tube communicating with a tuyere directed into the blast furnace, the injection tube comprising at least one plasma furnace through which the said gas passes, the at least one plasma furnace being coaxial with and adjacent to the tuyere; and simultaneously supplying a plasma to the at least one plasma furnace, whereby the plasma heats the said gas.
6. A method as claimed in claim 5, in which the plasma is supplied to the at least one plasma furnace by at least one arc plasma torch fed with a pilot plasma-forming gas.
7. A method as claimed in claim 6, in which the pilot plasma-forming gas is selected from the group consisting of nitrogen, argon, and gases inert to the contents of the shaft furnace.
8. A method as claimed in claim 6, in which the pilot plasma-forming gas is industrially pure hydrogen.
9. A method as claimed in claim 6, in which the pilot plasma-forming gas is reducing gas containing major quantities of hydrogen, CO and nitrogen and minor quantities of H2O and CO2.
10. A method as claimed in claim 5, in which the gas supplied through the supply duct is pre-heated to a temperature of 900°C to 1400°C before being passed through the injection tube.
11. A method as claimed in claim 5, in which the injection tube has two plasma furnaces in series.
12. A method as claimed in claim 11, in which reducing gas is supplied through the supply duct and is heated in two stages in the respective plasma furnaces, the gas being raised to a temperature of 1700°C to 2500°C
in the second stage.
in the second stage.
13. A method as claimed in claim 11, in which a gas consisting of hydrocarbon gas to be reformed and oxidizing gas is supplied through the supply duct, whereby reforming of the hydrocarbon gas takes place in one plasma furnace and heating takes place in the other.
14. A method as claimed in claim 6, in which, when injection of the reducing gas into the shaft furnace is suspended an inert gas is blown into the at least one plasma furnace through the at least one plasma torch.
15. A method as claimed in claim 5, further comprising measuring the pressure in the shaft furnace, and regulating the intensity of the electric current feeding the at least one plasma furnace as a function of the measured pressure, thereby maintaining the consumed electric power constant.
16. A method as claimed in claim 6, including assisting the stability of the electric arc by seeding the pilot gas by thoroughly dispersing at least one readily ionizable compound in the pilot gas.
17. A method as claimed in claim 16, in which the compound is selected from the group consisting of alkali metal compounds and alkaline-earth metal compounds.
18. A method as claimed in claim 17, in which the compound is a halide.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BE6044528A BE813118A (en) | 1974-03-29 | 1974-03-29 | DEVICE FOR INJECTING HOT REDUCING GAS INTO A TANK OVEN AND IMPLEMENTATION PROCEDURE. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1050265A true CA1050265A (en) | 1979-03-13 |
Family
ID=3874571
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA223,263A Expired CA1050265A (en) | 1974-03-29 | 1975-03-27 | Apparatus for injection of hot reducing gas into a shaft |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS50130617A (en) |
| BE (1) | BE813118A (en) |
| CA (1) | CA1050265A (en) |
| DE (1) | DE2512178C3 (en) |
| FR (1) | FR2265863B1 (en) |
| GB (1) | GB1488976A (en) |
| LU (1) | LU72058A1 (en) |
| NL (1) | NL7502814A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4421553A (en) * | 1980-05-06 | 1983-12-20 | Centre De Recherches Metallurgiques | Process for operating a blast furnace |
| SE8306107D0 (en) * | 1983-11-07 | 1983-11-07 | Skf Steel Eng Ab | TETNINGSANORDNING |
| AT384007B (en) * | 1984-04-02 | 1987-09-25 | Voest Alpine Ag | METHOD FOR PRODUCING SYNTHESIS GAS AND DEVICE FOR IMPLEMENTING THE METHOD |
| FR2576403B1 (en) * | 1985-01-21 | 1987-03-06 | Siderurgie Fse Inst Rech | DEVICE FOR COOLING A PIPE ON WHICH A SECONDARY PIPE FOR THE SUPPLY OF A SUPERHEATED GAS IS STITCHED |
| SE500956C2 (en) * | 1991-01-17 | 1994-10-10 | Ssab Tunnplaat Ab | Blast position with carbon injection lance |
-
1974
- 1974-03-29 BE BE6044528A patent/BE813118A/en not_active IP Right Cessation
-
1975
- 1975-03-07 FR FR7507961A patent/FR2265863B1/fr not_active Expired
- 1975-03-10 NL NL7502814A patent/NL7502814A/en not_active Application Discontinuation
- 1975-03-17 LU LU72058A patent/LU72058A1/xx unknown
- 1975-03-20 GB GB1173375A patent/GB1488976A/en not_active Expired
- 1975-03-20 DE DE19752512178 patent/DE2512178C3/en not_active Expired
- 1975-03-25 JP JP3602575A patent/JPS50130617A/ja active Pending
- 1975-03-27 CA CA223,263A patent/CA1050265A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2265863B1 (en) | 1979-01-05 |
| DE2512178A1 (en) | 1975-10-09 |
| BE813118A (en) | 1974-09-30 |
| GB1488976A (en) | 1977-10-19 |
| LU72058A1 (en) | 1975-08-20 |
| NL7502814A (en) | 1975-10-01 |
| FR2265863A1 (en) | 1975-10-24 |
| DE2512178C3 (en) | 1979-02-08 |
| JPS50130617A (en) | 1975-10-16 |
| DE2512178B2 (en) | 1978-06-01 |
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