JP5527168B2 - Converter exhaust gas recovery device and converter exhaust gas recovery method - Google Patents

Description

  The present invention relates to a converter exhaust gas recovery apparatus and a converter exhaust gas recovery method that collects exhaust gas generated in a converter and recovers non-combustible combustible gas.

  The exhaust gas generated during converter refining is a gas containing carbon monoxide at a high concentration. As a method of treating this converter exhaust gas, a combustion type exhaust gas treatment device that recovers energy with a boiler after burning carbon monoxide in the exhaust gas at the top of the converter furnace, and recovering without burning carbon monoxide And a non-combustion type exhaust gas treatment device. As described in Non-Patent Document 1, an OG-type converter exhaust gas recovery device is typically used as a non-combustion type exhaust gas treatment device. FIG. 1 shows an overall schematic diagram of an OG type converter exhaust gas recovery device. In the OG type converter exhaust gas recovery device, the converter exhaust gas is guided to the hood 2 at the furnace port of the converter 1 and the gas temperature is reduced by the radiant unit 3 and then wet dust collection is performed by the two-stage venturi scrubber 4. The gas is attracted by the induction blower 5, and the converter exhaust gas is collected in the gas holder 10 via the flue 11.

  In refining in a converter, hot metal is first charged into the converter, and decarburization refining is mainly performed by converter blowing. After the refining is completed, the molten steel is discharged and the slag is discharged, and the molten iron is charged for the next refining. In the converter refining cycle as described above, it is during converter blowing that a large amount of exhaust gas containing a high concentration of carbon monoxide is generated. No exhaust gas is generated during non-blowing. Further, immediately after the start of blowing, the amount of exhaust gas generated increases rapidly, but the exhaust gas contains high concentration of oxygen. As time elapses from the start of blowing, the oxygen concentration in the exhaust gas decreases and the carbon monoxide concentration increases.

  Immediately after the start of blowing, it is not preferable to collect the exhaust gas from a point in time when the concentration of carbon monoxide in the exhaust gas is not high, since the quality of the recovered exhaust gas as a fuel gas is reduced. Therefore, as described in Patent Document 1, exhaust gas is released into the atmosphere at the start of converter blowing, and a CO concentration analyzer in the gas (furnace top CO analysis) is connected to the exhaust gas path of the radiant section 3 at the top of the converter furnace. A total 22) is provided, and the recovery of the exhaust gas to the gas holder is not started until the carbon monoxide concentration in the exhaust gas rises above a certain concentration.

  Immediately after the start of blowing, the oxygen concentration in the exhaust gas is high. Further, when the outside gas is mixed due to damage or the like in the exhaust gas path, the oxygen concentration in the exhaust gas may increase. If the exhaust gas is recovered when the oxygen concentration in the exhaust gas is high, the components of the exhaust gas may exceed the explosion limit. Therefore, a gas oxygen concentration analyzer (furnace top oxygen analyzer 21) is provided in the exhaust gas path of the radiant section 3 at the top of the converter furnace, and the gas oxygen concentration analyzer (under the furnace) is placed in the flue 11 after wet dust collection. An oxygen analyzer 23) is provided, and the exhaust gas is collected in the gas holder 10 only when the oxygen concentration in the exhaust gas at the two locations is below a certain concentration.

  At the start of blowing, the recovery valve 9 is closed, and the exhaust gas from the flue 11 is discharged to the diffusion tower 8 by operating the three-way valve 6. After the start of blowing, the carbon monoxide concentration measured by the furnace top CO analyzer 22 becomes a certain concentration or more, for example, 25% or more, and at two locations measured by the furnace top oxygen analyzer 21 and the furnace oxygen analyzer 23. The recovery valve 9 is opened only when the condition that the oxygen concentration in the exhaust gas is equal to or lower than a certain concentration, for example, 2% or less, and the exhaust gas path is switched by operating the three-way valve 6 to the exhaust gas holder 10. Start collecting.

  In the analysis of oxygen concentration in converter exhaust gas, a method of sampling and analyzing the gas in the flue is common. For example, a magnetic oxygen analyzer using a wet sampler is used. The gas is sampled from the flue using a water flow, the sample gas is introduced into the magnetic oxygen analyzer via the drain separator, the gas cooler, and the drain separator, and the oxygen concentration in the sample gas is measured.

JP-A-5-209212 JP 2002-277391 A JP 2007-170841 A

Edited by the Japan Iron and Steel Institute, “Third Edition Steel Handbook II Steelmaking and Steelmaking”, page 462

  The time required for the converter exhaust gas to move through the exhaust gas path and pass the position of the furnace top oxygen analyzer 21 to pass the position of the furnace oxygen analyzer 23 is about 30 seconds. However, when the time transition of the gas concentration analyzed by the gas analyzer is compared immediately after the start of the converter blowing, the oxygen concentration in the gas analyzed by the furnace top oxygen analyzer 21 becomes 2% or less, and the oxygen analysis under the furnace About 110 seconds had elapsed until the oxygen concentration in the gas analyzed in total 23 became 2% or less. In the oxygen analysis by the in-furnace oxygen analyzer 23, it is presumed that there is a response delay from when the gas is sampled from the exhaust gas path until the analysis result of the gas is obtained. Since there is a delay in the analysis response in the in-furnace oxygen analyzer 23, the time to start collecting exhaust gas in the gas holder 10 after the start of converter blowing is delayed, and the converter exhaust gas, which is a combustible gas, is sufficiently effective. It was not available.

  In the converter exhaust gas recovery device for collecting exhaust gas generated in the converter and recovering non-combustible combustible gas, the present invention reduces the analysis response delay of the oxygen analysis in the gas in the exhaust gas path after dust collection, An object of the present invention is to provide a converter exhaust gas recovery device and a converter exhaust gas recovery method capable of increasing the recovery amount of converter exhaust gas.

  As gas analyzers, for example, Patent Documents 2 and 3 disclose laser-type gas analyzers that irradiate a measurement gas with laser light and measure a gas concentration based on a change in light amount due to light absorption of the laser light. Laser light is irradiated toward the measurement gas flowing in the pipeline, and the gas component is detected by detecting the laser light transmitted through the measurement space. When a laser gas analyzer was used as the in-furnace oxygen analyzer of the converter exhaust gas recovery system, it became clear that the response delay of the oxygen analysis in the gas could be reduced.

This invention is made | formed based on the said knowledge, The place made into the summary is as follows.
(1) A converter exhaust gas recovery device that collects exhaust gas generated in a converter and recovers non-combustible combustible gas. Hereinafter referred to as “furnace top oxygen analyzer 21”) and gas CO concentration analyzer (hereinafter referred to as “furnace top CO analyzer 22”), and the gas oxygen analyzer (hereinafter referred to as “furnace top CO analyzer 22”) in the exhaust gas path after dust collection. As the furnace oxygen analyzer 23, the exhaust gas in the flue is irradiated with laser light, and the gas concentration is measured from the change in the amount of light due to the light absorption of the laser light. Using a laser gas analyzer 25 ,
An insertion tube 28 is disposed in the flue so as to surround the optical path of the laser beam 30 on one or both of the laser irradiation unit 26 side and the laser detector 27 side of the laser gas analyzer 25. A converter exhaust gas recovery device characterized by flowing nitrogen gas .
(2) A converter exhaust gas recovery method carried out using the converter exhaust gas recovery apparatus described in (1) above, wherein when the converter blowing is started, the generated converter exhaust gas is diffused into the atmosphere, When the oxygen concentration in the gas measured by the analyzer 21 and the in-furnace oxygen analyzer 23 is lower than the predetermined concentration and the CO concentration in the gas measured by the top CO analyzer 22 is higher than the predetermined concentration, the gas is discharged into the atmosphere. A converter exhaust gas recovery method characterized by switching from emission to recovery to the gas holder 10.

  The present invention relates to a laser gas analyzer as an in-furnace oxygen analyzer 23 provided in an exhaust gas path after dust collection in the recovery of a converter exhaust gas that collects exhaust gas generated in a converter and recovers non-combustible combustible gas. By using 25, the response delay of the oxygen analysis in the gas can be reduced, and the recovery amount of the converter exhaust gas can be increased.

It is the whole OG system converter exhaust gas recovery device schematic. It is a figure which shows the condition which used the laser type gas analyzer as a furnace oxygen analyzer. It is a figure which shows transition of the analysis result of the gas analyzer after a converter blowing start.

  The whole of the OG type converter exhaust gas recovery device is shown in FIG.

  The exhaust gas generated in the converter is collected by a hood 2 arranged at the upper part of the converter 1, the gas is cooled by a radiating section 3, and then wet dust is collected by a two-stage venturi scrubber 4. The exhaust gas after wet dust collection is blown by the induction blower 5 provided in the middle of the flue 11 and reaches the three-way valve 6. One path branched by the three-way valve 6 reaches the diffusion tower 8, and the exhaust gas flowing through this path is diffused into the atmosphere. The other path branched by the three-way valve 6 reaches the gas holder 10 via the recovery valve 9. By operating the three-way valve 6, the exhaust gas discharged from the converter 1 is guided to the gas holder 10 or diffused from the stripping tower 8.

  A gas oxygen concentration analyzer (furnace top oxygen analyzer 21) and a gas CO concentration analyzer (furnace top CO analyzer 22) are arranged in the radiation section 3 which is the exhaust gas path before wet dust collection at the top of the converter furnace. . Further, an in-gas oxygen analyzer (under-furnace oxygen analyzer 23) is disposed in the flue 11 which is an exhaust gas path after wet dust collection. Usually, the in-furnace oxygen analyzer 23 is arranged in the flue 11 on the downstream side of the induction fan 5.

  Whether the converter exhaust gas is collected in the gas holder 10 or is released into the atmosphere via the diffusion tower 8 is determined based on the gas analysis result of the exhaust gas. The carbon monoxide concentration in the exhaust gas analyzed by the furnace top CO analyzer 22 is 25% or more, for example, and the oxygen concentration in the exhaust gas analyzed by the furnace top oxygen analyzer 21 and the furnace oxygen analyzer 23 is both 2% or less, for example. In this case, the recovery condition is satisfied, and the exhaust gas is recovered in the gas holder 10. If even one of the conditions is not met, the recovery condition is not established, and the exhaust gas is diffused from the diffusion tower 8. At the start of converter blowing, the converter exhaust gas is released from the diffusion tower 8. With the progress of blowing, the oxygen concentration in the gas analyzed by the furnace top oxygen analyzer 21 and the furnace oxygen analyzer 23 decreases, and the carbon monoxide concentration in the gas analyzed by the furnace CO analyzer 22 increases. . When the analyzed gas component reaches the recovery condition, the three-way valve 6 is operated to the recovery side, the on-off valve 9 is opened, and gas recovery to the gas holder 10 is started.

  In the present invention, as the in-furnace oxygen analyzer 23, a laser gas analyzer 25 is used which irradiates the flue gas with laser light and measures the gas concentration from the change in the amount of light due to light absorption of the laser light. As shown in FIG. 2, the laser gas analyzer includes a laser irradiation unit 26 that irradiates a measurement laser beam toward a space to be measured, and a laser light receiving unit 27 that detects the measurement laser beam 30 that has passed through the measurement space. And an arithmetic processing unit 31 for processing an output signal of the laser light receiving unit. The measurement laser light is irradiated to the measurement space while continuously changing the wavelength of the laser light 30 emitted from the laser irradiation unit 26, and the output signal of the laser light receiving unit 27 obtained as a result is analyzed and processed by the arithmetic processing unit 31. By calculating, the average concentration and average temperature data of the molecules / atoms to be detected are obtained. Even if the measurement gas contains high-concentration dust, the component concentration in the gas can be analyzed with high accuracy.

  In the present invention, a laser gas analyzer 25 is installed as an in-furnace oxygen analyzer 23 in the flue 11 which is an exhaust gas path after wet dust collection. Usually, as shown in FIG. 1, it provides in the exhaust gas path | route downstream of an induction fan. As shown in FIG. 2A, a laser irradiation unit 26 is disposed outside the flue 11, and the laser light 30 is emitted toward the exhaust gas in the flue. A laser light receiving unit 27 is disposed on the outer side of the flue 11 opposite to the laser irradiation unit 26. The laser gas analyzer arranged in this way can analyze the oxygen concentration of the exhaust gas flowing through the flue.

  The flue 11 on the downstream side of the induction fan has a large diameter exceeding 2 m. The length of the optical path of the laser beam 30 from the laser irradiation unit 26 to the laser light receiving unit 27 is equal to or greater than the diameter of the flue 11. When there are a lot of dust and water droplets in the exhaust gas, if the optical path of the laser beam 30 is too long, the laser beam may be scattered by the dust and water droplets, making measurement difficult. In such a case, as shown in FIG. 2B, an insertion tube 28 is disposed so as to surround the optical path of the laser beam 30 on one or both of the laser irradiation unit 26 side and the laser detector 27 side. The problem can be solved. In the insertion tube 28, nitrogen gas is flowed as the purge gas 29 so as to flow toward the tip of the insertion tube inside the furnace. Thereby, the inside of the insertion tube is always filled with clean nitrogen gas. The optical path through which the measurement gas flows is between the tip of the insertion tube 28 extending from both sides. By installing the insertion tube 28, it is possible to shorten the laser light path passing through the measurement gas, and even if dust or water droplets are contained in the exhaust gas, it is possible to analyze the oxygen concentration in the gas satisfactorily. Become.

  In the present invention, the furnace top oxygen analyzer 21 and the furnace top CO analyzer 22 may be the same analyzer as in the past. Conventionally, the delay in response to gas analysis has been noticeable in the furnace oxygen analyzer 23. By simply changing the furnace oxygen analyzer 23 from a magnetic oxygen analyzer to a laser gas analyzer 25, the converter exhaust gas This is because the recovery start time of the gas can be advanced and the amount of recovered gas can be increased.

  In the converter exhaust gas recovery method of the present invention, the converter exhaust gas recovery apparatus of the present invention is used, and when the converter blowing is started, the generated converter exhaust gas is released to the atmosphere, and the furnace top oxygen analyzer 21 and the furnace When the oxygen concentration in the gas measured by the lower oxygen analyzer 23 is lower than the predetermined concentration and the CO concentration in the gas measured by the furnace top CO analyzer 22 is higher than the predetermined concentration, the gas is removed from the atmosphere to the gas holder 10. Switch to recovery. Since the laser gas analyzer 25 is used as the in-furnace oxygen analyzer 23, the recovery start time of the converter exhaust gas can be advanced, and the amount of gas recovered can be increased.

  The OG type converter exhaust gas recovery device has been described above as an example. However, the present invention can also be implemented with other methods when the downstream oxygen concentration is a recovery condition in the non-combustion type gas recovery device. .

  The present invention was applied to an OG-type converter exhaust gas recovery apparatus for a 300-ton converter. The whole of the OG converter exhaust gas recovery device is as shown in FIG.

  A furnace top oxygen analyzer 21 and a furnace top CO analyzer 22 are installed in the exhaust gas path of the radiation section 3 at the top of the converter furnace, and a furnace oxygen analyzer 23 is installed in the flue 11 after wet dust collection. At the start of blowing, the recovery valve 9 is closed, and the exhaust gas from the flue 11 is discharged to the diffusion tower 8 by operating the three-way valve 6. After the start of blowing, the carbon monoxide concentration measured by the furnace top CO analyzer 22 is 25% or more, and the oxygen concentrations in the two exhaust gases measured by the furnace top oxygen analyzer 21 and the furnace oxygen analyzer 23 The recovery valve 9 is opened only when the condition of 2% or less is established, and the exhaust gas path is switched by operating the three-way valve 6 to start recovery of the exhaust gas to the gas holder 10.

  In the conventional example, a magnetic analyzer was used for the furnace top oxygen analyzer 21 and the furnace oxygen analyzer 23, and an infrared analyzer was used for the furnace CO analyzer 22.

  In the present invention example, only the in-furnace oxygen analyzer 23 is changed from the conventional magnetic oxygen analyzer to the laser gas analyzer 25. A laser type gas analyzer 25 was installed in the flue 11 on the downstream side of the induction blower 5 as shown in FIG. A laser irradiation unit 26 is disposed outside the flue 11, the laser light 30 is irradiated toward the exhaust gas in the flue, and a laser light receiving unit 27 is disposed outside the flue 11 opposite to the laser irradiation unit 26. . A measurement laser beam is irradiated onto the measurement space while continuously changing the wavelength of the laser beam 30 emitted from the laser irradiation unit 26, and the output signal of the laser receiving unit 27 obtained as a result is analyzed and calculated by the arithmetic processing unit 31. To analyze the oxygen concentration in the exhaust gas passing through the flue. Since the flue 11 has a large diameter of 2.4 m, an insertion tube 28 is provided as shown in FIG. In the insertion tube 28, nitrogen gas is flowed as the purge gas 29 so as to flow toward the tip of the insertion tube inside the furnace. The interval from the tip of the insertion tube 28 extending from both sides to the tip was 1 m. Thereby, the length of the optical path of the laser beam 30 passing through the exhaust gas becomes 1 m, and the oxygen concentration in the exhaust gas can be analyzed without any problem even if the exhaust gas contains dust or moisture.

  FIG. 3 shows the passage of time since the start of blowing in the converter 1 and the time transition of the gas analysis results by the furnace top oxygen analyzer 21, the furnace top CO analyzer 22, and the furnace oxygen analyzer 23. ing. Regarding the in-furnace oxygen analyzer 23, both conventional data by a magnetic analyzer and data of the present invention by a laser gas analyzer are listed. In the figure, timings of the furnace top CO analyzer condition establishment 41, the furnace oxygen analyzer condition establishment 42 in the conventional method, and the furnace oxygen analyzer condition establishment 43 in the method of the present invention are illustrated.

  The horizontal axis in FIG. 1 starts blowing in about 20 seconds.

  In the conventional example, first, the condition of the furnace top oxygen analyzer is satisfied, and further, the furnace top CO analyzer condition is satisfied 41 after about 90 seconds, and then the furnace oxygen analyzer condition is satisfied 42 after about 170 seconds. At this time, “recovery conditions are met”, and a sequence for gas recovery is started.

  In the example of the present invention, first, the furnace oxygen analyzer condition is satisfied 43 in about 60 seconds, and then the furnace CO analyzer condition 41 is satisfied in about 90 seconds. At this time, “recovery conditions are met”, and a sequence for gas recovery is started. Therefore, in comparison with the conventional example, in the example of the present invention, the recovery condition is satisfied from 170 seconds to 90 seconds, and the time reduction of 80 seconds can be realized.

DESCRIPTION OF SYMBOLS 1 Converter 2 Hood 3 Radiation part 4 Venturi scrubber 5 Induction fan 6 Three-way valve 7 Bypass valve 8 Exhaust tower 9 Recovery valve 10 Gas holder 11 Flue 21 Furnace top oxygen analyzer 22 Furnace top CO analyzer 23 Furnace oxygen analyzer 25 Laser type gas analyzer 26 Laser irradiation unit 27 Laser light receiving unit 28 Insertion tube 29 Purge gas 30 Laser beam 31 Arithmetic processing unit 41 Furnace top CO analyzer condition establishment 42 Conventional furnace analyzer condition establishment 43 Conventional method Of in-furnace oxygen analyzer conditions in Japan

Claims (2)

A converter exhaust gas recovery device that collects exhaust gas generated in a converter and recovers flammable gas in a non-combustible manner. Gas oxygen concentration analyzer (hereinafter referred to as “furnace top CO analyzer”) and gas oxygen analyzer (hereinafter referred to as “furnace oxygen analysis”) in the exhaust gas path after dust collection. Called "total")
As the in-furnace oxygen analyzer, a laser gas analyzer is used that irradiates the flue gas with laser light and measures the gas concentration from the light quantity change due to light absorption of the laser light .
An insertion tube is disposed in the flue so as to surround the optical path of the laser beam on one or both of the laser irradiation part side and the laser detector side of the laser gas analyzer, and nitrogen gas is allowed to flow through the insertion tube. A converter exhaust gas recovery apparatus characterized by that.   A converter exhaust gas recovery method performed using the converter exhaust gas recovery apparatus according to claim 1, wherein when the converter blowing is started, the generated converter exhaust gas is diffused into the atmosphere, and a furnace top oxygen analyzer and a furnace When the oxygen concentration in the gas measured with the lower oxygen analyzer is lower than the predetermined concentration and the CO concentration in the gas measured with the furnace CO analyzer is higher than the predetermined concentration, the gas is recovered from the atmospheric discharge to the gas holder. The converter exhaust gas recovery method characterized by switching to.

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