Direct reduction shaft furnace with probe for internal gas analysis

Abstract

A direct reduction shaft furnace having at least one probe disposed vertically within its reduction zone. The probe preferably extends from the top to the bottom of the reduction zone. The probe allows for gas sampling along its length and delivery of the gas to at least one type of gas analysis device. The probe can also allow for measurement of the temperature and pressure of the gas sample at the time of collection.

Description

[0001] This invention patent application is a divisional application of the invention patent application filed on November 13, 2018, with application number 201880099457.9 and invention title "Direct Reduction Shaft Furnace with Probe for Internal Gas Analysis". Technical Field

[0002] This invention generally relates to any type of shaft furnace, including direct reduction shaft furnaces. More specifically, this invention relates to internal sensors for direct reduction shaft furnaces. In particular, this invention relates to direct reduction shaft furnaces having at least one probe for measuring temperature and collecting gas samples at different levels within their reduction zone. Background Technology

[0003] The direct reduction process, used for producing high-quality metallized pellets, boasts extremely high thermal efficiency. Direct reduced iron (DRI) is produced by directly reducing iron ore (in the form of lumps, pellets, or fines) to iron using reducing gases. Hematite / magnetite is suitable for direct reduction.

[0004] The name "reduced iron" comes from the chemical changes that occur when iron ore is heated in a furnace at high temperatures in the presence of hydrocarbon-rich gases, carbon monoxide, hydrogen, or elemental carbon. Direct reduction refers to the process of reducing iron oxides to metallic iron at temperatures below the melting point of iron. The product of such a solid-state process is called direct reduced iron.

[0005] The process employs a vertical furnace 1, as illustrated in the diagram. Figure 1 The vertical shaft furnace 1 has a reduction zone 2 in the upper region and a cooling zone 3 in the lower region. Hot reducing gas from any external source is introduced into the reduction zone 2 via gas inlet 4. For the purposes of describing the entire process, the reducing gas used herein consists primarily of CO and H2, which are typically produced by continuous catalytic reforming of hydrocarbons (e.g., natural gas, petroleum distillates, methane, ethane, propane, butane, or other readily volatile hydrocarbons) or by syngas from any source (e.g., a coal gasifier). The purpose of the reduction process is to remove oxygen contained in various forms of iron ore (graded ore, concentrate, pellets, rolled steel scale, furnace ash, etc.) to convert the ore into metallic iron without melting it. The reduction process temperature is typically between 800°C and 1200°C.

[0006] At least 85% and preferably at least 90% of the metallized products are produced. A gravity flow of the metal oxide material or charge is established by loading granular metal oxide material into the upper part of the furnace and removing the metallized products from the bottom. A hot reducing gas containing CO and H2 as reducing agents is introduced into the material flow through an annular duct and a tuyer inlet system at the furnace end. The gas flows counter-currently upwards through the material, reducing most of the metal oxides and forming a top gas. The top gas is removed from the upper part of the furnace through gas outlet 5.

[0007] In a direct reduction (DR) shaft furnace, the descending charge faces different gas compositions and temperatures at each level of the furnace. The overall reaction in a DR furnace is:

[0008] Overall reaction

[0009]

[0010]

[0011] However, numerous intermediate reactions exist to arrive at the final overall reaction. These intermediate reactions include:

[0012]

[0013] Currently, there is no way to determine what reactions are occurring at any level within the reduction zone at any given time. Therefore, since there are currently no in-situ measurements of gas analysis inside the shaft furnace, technicians can only model the DR reduction zone based on its inputs and outputs (gas and solids). Measuring the gas composition, temperature, and pressure inside the furnace can provide useful information such as reduction potentials at different levels, reduction kinetics, the evolution of chemical reactions along the shaft furnace, pressure drops, carbonization, in-situ reforming, and temperature distribution. Therefore, there is a need in the art for direct reduction shaft furnaces that include thermal-gas probes in their reduction zone. Summary of the Invention

[0014] This invention relates to an apparatus for the direct reduction of oxide ores. The apparatus includes a vertical shaft furnace having an oxide ore reduction zone and at least one probe for sampling gases from within the reduction zone of the vertical shaft furnace. The probe may be vertically positioned within the reduction zone and extend through the entire reduction zone. The probe may include a plurality of sampling tubes. Each sampling tube may have an upper portion and an end portion. The sampling tubes may be housed within at least one support tube. The support tube may enclose and support a portion of the upper portion of all sampling tubes.

[0015] The end of each sampling tube can be configured to allow the introduction of a gas sample therethrough. The end of each sampling tube may also include a thermocouple disposed therein to measure the temperature of the gas sample. Each sampling tube has a different length and extends downwards through the reduction zone a different distance to allow sample introduction from different depths within the reduction zone.

[0016] Each sampling tube may be the same length as the rest of the sampling tubes. Each sampling tube may have a gas inlet configured to penetrate its wall. Each gas inlet is located at a different position along the length of the sampling tube than the inlets on the rest of the sampling tubes. Each gas inlet may be configured to allow the introduction of a gas sample through it. The end of each sampling tube may be closed to prevent gas from entering through it. Each sampling tube may also include a thermocouple configured adjacent to the gas inlet for measuring the temperature of the gas sample.

[0017] The first sampling tube may be concentrically nested within the support tube. The first sampling tube may be longer than the support tube and may have an end protruding from the support tube. Each subsequent sampling tube may be concentrically nested within the preceding sampling tube and may be longer than the preceding sampling tube, having an end protruding from the preceding sampling tube. The end of each sampling tube may be configured to allow the introduction of a gas sample therethrough. The end of each sampling tube may also include a thermocouple disposed therein for measuring the temperature of the gas sample.

[0018] The equipment for the direct reduction of oxide ores may also include a gas analysis system and a pressure measurement system. The gas analysis system may include a gas cooling system to cool the gas sample prior to compositional analysis and pressure measurement. The gas analysis system may also include a gas analysis device, which may be a mass spectrometer or a laser / infrared analyzer. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a vertical furnace in which the gas analysis probe of the present invention can be installed;

[0020] Figure 2 A is a cross section that penetrates the diameter of the probe 6 used in the first embodiment of the present invention;

[0021] Figure 2 B is a side view of the first embodiment of probe 6;

[0022] Figure 2 C is a 3D perspective view of the first embodiment of probe 6;

[0023] Figure 3 This is a side view of the second embodiment of probe 6;

[0024] Figure 4A side view of another embodiment of the probe 6 used in the present invention is depicted;

[0025] Figure 5 This is a 3D perspective view of a cannulated embodiment of the probe 6 used in this invention;

[0026] Figure 6 A schematic diagram of the combination of DR vertical furnace 1 and probe 6 vertically arranged in the reduction zone is shown. Detailed Implementation

[0027] This invention relates to a DR vertical furnace having at least one probe vertically disposed within its reduction zone. The probe preferably extends from the top to the bottom of the reduction zone. The probe allows for gas sampling along its length and delivery of the gas to at least one type of gas analysis device and pressure measuring instrument. The probe also allows for measurement of the temperature of the gas sample during sample collection. Therefore, the combination of the DR furnace and probe of this invention allows for the collection of gas samples and temperatures at different levels within the furnace. The probe can be mounted vertically at one or more locations along the diameter of the DR vertical furnace.

[0028] Figure 2 Figures A through 2C illustrate different embodiments of the probe 6 used in this invention. This embodiment has individual gas sampling tubes 8 of varying lengths and a support tube 7. In this embodiment, all gas sampling tubes 8 are longer than the support tube 7. Gas samples are drawn into the sampling tubes through the open ends. Thermocouples (not shown in the figures) can be positioned at the open ends of each sampling tube 8. This allows for temperature distribution measurements of the reduction zone of the DR furnace and indicates the temperature of the gas collected for analysis. In this embodiment, all sampling tubes 8 have different lengths to collect gas samples along the entire reduction zone. Figure 2 A is the cross section with the diameter of the first embodiment of the probe 6. Figure 2 B is a side view of the first embodiment of probe 6. Finally, Figure 2 C is a 3D perspective view of the first embodiment of probe 6.

[0029] In another implementation, multiple support tubes 7 may exist. Figure 3 This is a side view of this second embodiment of probe 6. Two or more support tubes 7 can accommodate sampling tubes 8. A gap may exist between support tubes 7' and 7'', and the sampling tube 8 may terminate in this gap to collect a sample at this level in the reduction zone. Similarly, thermocouples (not shown in the figure) may be placed at the open end of each sampling tube 8.

[0030] Figure 4Another embodiment of the probe 6 used in this invention is depicted. In this embodiment, a single support tube 7 is present, and all sampling tubes 8 are of approximately the same length. Each sampling tube 8 has a sampling port 9 at a different location thereon to allow gas sampling along the entire reduction zone. As described above, a thermocouple (not shown) may be mounted adjacent to the sampling port 9 in each sampling tube 8.

[0031] Figure 5 A cannulated embodiment of the probe 6 used in this invention is depicted. In this embodiment, a sampling tube 8 is nested concentrically within a support tube 7 in a cannulated manner. Thus, a first sampling tube 8 is nested concentrically within the support tube 7. The first sampling tube 8 is longer than the support tube 7 and protrudes from it. A subsequent sampling tube 8 is nested concentrically within the first sampling tube. This concentric nesting continues with additional sampling tubes 8 to provide as many gas sampling tubes 8 as necessary or desired for sampling the entire reduction zone. Each additional sampling tube 8 is longer than the preceding sampling port in which it is nested and protrudes from it. As in some other embodiments, a thermocouple (not shown) may be mounted at the end (gas sampling) of each sampling tube 8.

[0032] The support tube 7 and the sampling port 8 are formed of materials selected to suit the high-temperature conditions and corrosive atmosphere of the DR furnace.

[0033] Typically, probe 6 is designed to collect gas samples at different levels within the reduction zone of the DR furnace, and (optionally) measure temperature. The gas samples will be used for gas analysis and pressure measurements. Probe 6 can be installed vertically at up to five different locations along the diameter of the DR vertical furnace reduction zone.

[0034] Figure 6 A schematic diagram of the vertical shaft furnace probe 6, and schematic diagrams of the temperature measurement system and gas analysis system connected thereto, are shown. The gas analysis system includes a gas delivery line 14 and a gas cooling device 10 for cooling the gas sample. The gas sample is then guided to both the gas composition analysis system 11 and the gas pressure measurement system 12. The temperature measurement system 13 includes a thermocouple / delivery line 15.

[0035] The sample analysis system 11 may include a mass spectrometer or a laser / infrared analyzer.

[0036] Probe 6 can be fixed to the furnace top. Fixing can be accomplished, for example, by welding a flange to the top of probe 6. The tubes (support tube 7 and sampling tube 8) can be welded together along their length to provide greater mechanical strength and resistance to bending and fracture.

[0037] According to embodiments of the present invention, the following notes are also disclosed:

[0038] Appendix 1. An apparatus for the direct reduction of metal ores, said apparatus comprising:

[0039] A vertical shaft furnace, wherein the shaft furnace has a metal ore reduction zone;

[0040] At least one probe, the at least one probe being used to sample gas from the reduction zone of the vertical furnace;

[0041] The at least one probe is vertically positioned within the reduction zone and extends through the entire reduction zone;

[0042] The probe includes a plurality of sampling tubes, each sampling tube having an upper part and an end part, and the sampling tubes are disposed within at least one support tube.

[0043] Note 2. The device according to Note 1, wherein the support tube wraps around and supports a portion of the upper part of all the sampling tubes.

[0044] Note 3. The apparatus according to Note 2, wherein the end of each of the sampling tubes is configured to allow the introduction of a gas sample therethrough.

[0045] Note 4. The apparatus according to Note 3, wherein the end of each of the sampling tubes further includes a thermocouple disposed therein for measuring the temperature of the gas sample.

[0046] Note 5. The device according to Note 4, wherein the sampling tubes each have different lengths and extend downward through the reduction zone by different distances to allow for the introduction of samples from different depths within the reduction zone.

[0047] Note 6. The device according to Note 2, wherein each of the sampling tubes:

[0048] The same length as the rest of the sampling tubes;

[0049] It has a gas inlet located through its wall at a position along its length different from the rest of the sampling tubes, and the gas inlet is configured to allow the introduction of a gas sample therethrough;

[0050] Its ends are sealed to prevent gas from entering through them.

[0051] Note 7. The apparatus according to Note 6, wherein each of the sampling tubes further includes a thermocouple disposed adjacent to the gas inlet to measure the temperature of the gas sample.

[0052] Note 8. The apparatus according to Note 1, wherein:

[0053] The first sampling tube is nested concentrically within the support tube, the first sampling tube being longer than the support tube and having an end protruding from the support tube;

[0054] Each subsequent sampling tube is nested concentrically within the preceding sampling tube and is longer than the preceding sampling tube, having an end that protrudes from the preceding sampling tube.

[0055] Note 9. The apparatus according to Note 8, wherein the end of each of the sampling tubes is configured to allow the introduction of a gas sample therethrough.

[0056] Note 10. The apparatus according to Note 9, wherein the end of each of the sampling tubes further includes a thermocouple disposed therein for measuring the temperature of the gas sample.

[0057] Note 11. The apparatus according to Note 1, wherein the apparatus further includes a gas analysis system.

[0058] Note 12. The apparatus according to Note 11, wherein the gas analysis system includes a gas cooling system to cool the gas sample prior to compositional analysis.

[0059] Note 13. The apparatus according to Note 12, wherein the gas analysis system further includes a gas composition analysis device.

[0060] Note 14. The apparatus according to Note 13, wherein the gas composition analysis device includes a mass spectrometer.

[0061] Note 15. The apparatus according to Note 13, wherein the gas analysis system further includes a gas pressure measurement system.

Claims

1. A direct reduction shaft furnace, the direct reduction shaft furnace having an oxide ore reduction zone and at least one probe, the at least one probe being used to sample gas from the reduction zone of the direct reduction shaft furnace; The at least one probe is vertically positioned within the reduction zone and extends through the entire reduction zone; The probe includes a plurality of sampling tubes, each sampling tube having an upper part and an end part, and the sampling tubes are disposed within at least one support tube; The first sampling tube is nested concentrically within the support tube, the first sampling tube being longer than the support tube and having an end protruding from the support tube; Each subsequent sampling tube is nested concentrically within the preceding sampling tube and is longer than the preceding sampling tube, having an end that protrudes from the preceding sampling tube.

2. The direct reduction furnace according to claim 1, wherein the support tube wraps around and supports the upper portion of all the sampling tubes.

3. The direct reduction shaft furnace according to claim 1 or 2, wherein the end of each of the sampling tubes is configured to allow the introduction of a gas sample therethrough.

4. The direct reduction shaft furnace according to claim 1 or 2, wherein the end of each of the sampling tubes further includes a thermocouple disposed therein for measuring the temperature of the gas sample.

5. The direct reduction vertical furnace according to claim 4, wherein the sampling tubes each have different lengths and extend downward through the reduction zone by different distances to allow for the introduction of samples from different depths in the reduction zone.

6. The direct reduction shaft furnace according to claim 1 or 2, wherein each of the sampling tubes: The same length as the rest of the sampling tubes; It has a gas inlet located through its wall at a position along its length different from the rest of the sampling tubes, and the gas inlet is configured to allow the introduction of a gas sample therethrough; Its ends are sealed to prevent gas from entering through them.

7. The direct reduction furnace according to claim 6, wherein each of the sampling tubes further includes a thermocouple disposed adjacent to the gas inlet to measure the temperature of the gas sample.

8. An apparatus for the direct reduction of oxide ores, comprising a direct reduction shaft furnace according to any one of claims 1 to 7.

9. The apparatus of claim 8, wherein the apparatus further comprises a gas analysis system.

10. The apparatus of claim 9, wherein the gas analysis system includes a gas cooling system to cool the gas sample prior to compositional analysis.

11. The apparatus according to claim 9 or 10, wherein the gas analysis system further comprises a gas composition analysis device.

12. The apparatus of claim 11, wherein the gas composition analysis device comprises a mass spectrometer.

13. The apparatus according to claim 9 or 10, wherein the gas analysis system further comprises a gas pressure measurement system.

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