JP2018091783A - Analytical method of gas component concentration, recovery method of exhaust gas, analyzer of gas component concentration and recovery facility of exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an analytical method of gas component concentration and an analyzer of gas component concentration which can accurately measure gas component concentration of exhaust gas, and a recovery method of exhaust gas and a recovery facility of exhaust gas which can safely and efficiently recover exhaust gas by use of the analytical method of gas component concentration or the analyzer of gas component concentration.SOLUTION: An analytical method of gas component concentration is given in which gas component concentration of exhaust gas is analyzed by penetration of laser beam through the exhaust gas which is generated in a steel converter 5 and dust of which is removed in a gas duct 20. The analytical method measures flow quantity or flow rate of the exhaust gas, makes the laser beam 3 penetrate through the gas duct 20 to measure absorbance of the penetrated laser beam 3 while inactive gas flows as purge gas 4 into insertion tubes 12a, 12b surrounding a part of the light path of the laser beam 3 and being arranged in the gas duct 20, and calculates the gas component concentration based on the measurement result of the flow quantity or the flow rate of the exhaust gas and the measurement result of the absorbance.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas component concentration analysis method, an exhaust gas recovery method, a gas component concentration analyzer, and an exhaust gas recovery facility.

  A converter-type smelting furnace (hereinafter referred to as a converter including a converter-type smelting furnace for pretreatment of hot metal), which is a refining facility used for dephosphorization pretreatment and decarburization of hot metal in the steelmaking process of steelworks. ), Exhaust gas is generated during the refining reaction during blowing (during acid sending refining treatment). Since the exhaust gas contains CO which is a combustible component, the generated exhaust gas is removed as dust and then recovered as non-combustible and combustible fuel gas. However, the CO concentration of the exhaust gas may be so low that it cannot be used as a fuel gas depending on the timing and conditions of blowing. In addition, the exhaust gas treatment facility is operated so as to increase the CO concentration in the exhaust gas by gradually reducing the atmospheric suction rate after the CO gas generation rate is increased and the atmospheric gas suction rate is increased when the blowing starts. Is done. For this reason, the exhaust gas transitions from a state in which the oxygen concentration is high in the initial stage of blowing to a state of fuel gas in which the oxygen concentration is low and the CO concentration is high through a state of combustion gas having a relatively low oxygen concentration and CO concentration. In addition, with changes in the state of exhaust gas, the flow rate of exhaust gas including the sucked air also changes greatly. For this reason, when recovering exhaust gas, the gas component concentration of the generated exhaust gas is usually measured, and recovery is performed only when it is determined that the fuel gas can be recovered from the measurement result.

  For example, in Patent Document 1, a gas oxygen concentration meter (hereinafter referred to as “furnace top oxygen analyzer”) and a gas CO concentration meter (hereinafter referred to as “furnace top”) are provided in the exhaust gas path before dust collection at the top of the converter furnace. And an exhaust gas recovery device having an in-gas oxygen analyzer (hereinafter referred to as “in-furnace oxygen analyzer”) in the exhaust gas path after dust collection. In the exhaust gas recovery apparatus described in Patent Document 1, as a furnace oxygen analyzer, laser gas analysis is performed by projecting laser light into flue exhaust gas and measuring the gas concentration from the change in the amount of light due to light absorption of the laser light. An insertion tube is placed in the flue so as to surround the optical path of the laser beam on at least one of the laser projection side and the laser detector side of the laser type gas analyzer, and purge gas is supplied to the insertion tube. Shed. In Patent Document 1, exhaust gas is diffused to the atmosphere at the start of converter blowing, and the oxygen concentration in the gas measured by the furnace top oxygen analyzer and the furnace oxygen analyzer becomes equal to or lower than the predetermined concentration, while the furnace top CO analysis is performed. When the CO concentration in the gas measured by the meter becomes a predetermined value or more, the exhaust gas is recovered by switching the exhaust gas from atmospheric emission to recovery to the gas holder. In Patent Document 1, instead of the magnetic oxygen analyzer that has been conventionally used as the oxygen analyzer, the laser oxygen analysis in the flue is adopted, so that the response time of the analysis is greatly shortened, and the converter The amount of exhaust gas recovered can be increased.

  The laser-type gas analyzer described in Patent Document 1 measures the absorbance corresponding to the absorption wavelength of the gas component to be analyzed by, for example, using a variable wavelength infrared semiconductor laser to compare the absorbance at a plurality of wavelengths. This is characterized in that it is less susceptible to changes in dust concentration. Also, at that time, if the dust concentration is high and the transmittance of the base laser beam is too low, it becomes difficult to measure with high accuracy.Therefore, an insertion tube that allows purge gas that is not the object of analysis to flow into the pipe is placed in the flue. A method is used in which the substantial optical path length (effective optical path length, the distance from the tip of the insertion tube to the tip of the insertion tube) in the flue space of the laser beam is shortened to ensure the necessary transmittance of the laser beam. .

  Patent Document 2 discloses that the effective optical path length is set so that the laser beam transmittance of the laser gas analyzer is 10% or more. Further, in Patent Document 2, as the exhaust gas flow velocity in the flue increases, the laser light transmittance decreases due to the scattering of the laser light by dust and water droplets, so that the predetermined laser light transmittance depends on the exhaust gas flow velocity. It is disclosed that an effective optical path length is set so as to be obtained. Furthermore, in Patent Document 2, in order to prevent intrusion and adhesion of dust and water droplets into the insertion tube, the tip of the insertion tube has a shape provided with a notch on the downstream side in the exhaust gas flow direction. Have been described.

Japanese Patent No. 5527168 International Publication No. 2013/179432

  By the way, in the analysis methods described in Patent Documents 1 and 2, the extinction coefficient 1 at the absorption wavelength corresponding to the gas component to be measured and the extinction coefficient 2 at other wavelengths are obtained in advance. Then, using the interval between the tips of the insertion tubes installed in the flue as the optical path length, the concentration of the gas component to be measured is calculated from the absorbance ratio (or light intensity ratio) at both wavelengths and the optical path length. However, there may be an error between the measurement result of the laser gas analyzer and the analysis result of the gas sample collected from the flue at the measurement timing. For this reason, when performing gas recovery using the analysis methods described in Patent Documents 1 and 2, gas calorie reduction or ignition due to a decrease in CO concentration or an increase in oxygen concentration of exhaust gas recovered in the gas holder. It was considered that the recovery amount was reduced because the possibility of recovering the exhaust gas could not be fully utilized because the determination of whether or not the exhaust gas could be recovered was strict.

  Therefore, the present invention has been made paying attention to the above-mentioned problem, and provides a gas component concentration analysis method and a gas component concentration analysis device that can accurately measure the gas component concentration of exhaust gas. It is an object. Another object of the present invention is to provide an exhaust gas recovery method and exhaust gas recovery equipment that can recover exhaust gas safely and efficiently using the gas component concentration analysis method or the gas component concentration analyzer. .

  In various operating conditions and measurement conditions, the present inventors have measured the exhaust gas measured in the flue by a laser gas analyzer and other gas chromatograph analyzers of exhaust gas samples collected from the flue at the same time as this measurement. By comparing the analysis value with a highly reliable analysis method, the cause of the measurement error of the gas component concentration by the laser type gas analyzer was investigated earnestly. As a result, it has been found that the exhaust gas flow rate and the exhaust gas flow velocity in the flue greatly affect the measurement error of the gas component concentration, and the present invention has been completed.

  Specifically, in the tube of the insertion tube and near the outlet, a mixed region of purge gas and exhaust gas occurs, and the mixed state such as the range of the mixed region and the gas volume ratio of both depends on the flow rate of the exhaust gas and the flow rate of the purge gas. Therefore, when the laser light passes through the exhaust gas, the substantial optical path length changes. From this, the present inventors estimated that this substantial change in the optical path length is the main cause of the error in the analytical value of the gas component concentration. When measuring with a laser gas analyzer, the optical path length is generally the distance between the tips of the pair of insertion tubes. For this reason, if at least one of the flow rate of the exhaust gas and the flow rate of the purge gas varies and the substantial optical path length of the laser beam changes, the absorbance of the laser beam changes, and therefore the calculation is performed using the set optical path length. An error occurs in the analysis value of the gas component concentration. Therefore, the present inventors, when using a laser type gas analyzer, when calculating the analytical value of the gas component concentration from the measured absorbance, the analytical value using the exhaust gas flow rate measured at the same timing, etc. A method for obtaining an accurate gas analysis value by correcting or adjusting the purge gas flow rate so as to offset the influence of the error in accordance with the exhaust gas flow rate, etc., was studied, and the present invention was completed. It was.

  According to one aspect of the present invention, there is provided a gas component concentration analysis method for analyzing the gas component concentration of the exhaust gas by transmitting laser light to the exhaust gas in the flue that is generated in the converter and removed from the dust. The flow rate or flow velocity of the exhaust gas is measured, and the laser is inserted into the flue with an inert gas flowing as a purge gas in an insertion tube disposed in the flue surrounding a part of the optical path of the laser beam. Transmitting light, measuring the absorbance of the transmitted laser beam, and calculating the gas component concentration based on the measurement result of the flow rate or flow rate of the exhaust gas and the measurement result of the absorbance A method for analyzing gas component concentrations is provided.

  According to one aspect of the present invention, there is provided a gas component concentration analysis method for analyzing the gas component concentration of the exhaust gas by transmitting laser light to the exhaust gas in the flue that is generated in the converter and removed from the dust. The flow rate or flow velocity of the exhaust gas is measured, and the laser is inserted into the flue with an inert gas flowing as a purge gas in an insertion tube disposed in the flue surrounding a part of the optical path of the laser beam. Measure the absorbance of the laser beam that has passed through the light, calculate the gas component concentration based on the measurement result of the absorbance, and measure the flow rate or flow velocity of the exhaust gas when measuring the absorbance. Based on the result, the flow rate of the purge gas is adjusted so as to cancel the error in the analysis result of the gas component concentration due to fluctuations in the flow rate or flow rate of the exhaust gas.析方 there is provided a method.

  According to one aspect of the present invention, exhaust gas generated in a converter is discharged to the atmosphere or recovered as fuel gas according to the gas component concentration, and the blowing process is started in the converter. The exhaust gas generated when the gas is discharged to the atmosphere, and the gas component concentration of the exhaust gas is analyzed using the gas component concentration analysis method during blowing in the converter to analyze the gas component concentration. As a result, when it is determined that the exhaust gas can be recovered, the exhaust gas is recovered as the fuel gas.

  According to one aspect of the present invention, there is provided a gas component concentration analyzer for analyzing the gas component concentration of the exhaust gas by transmitting laser light through the flue gas generated in the converter and dedusted in the flue. A measuring unit for measuring the flow rate or flow velocity of the exhaust gas, an insertion tube disposed in the flue surrounding a part of the optical path of the laser light, and a purge gas for flowing an inert gas as a purge gas in the insertion tube A supply unit, a light projecting unit that transmits the laser light by projecting the laser light, and a laser that transmits the laser light through the flue by receiving the projected laser light. The gas component concentration is calculated based on a light receiving unit that measures light absorbance, a measurement result of the flow rate or flow rate of the exhaust gas by the measurement unit, and a measurement result of the absorbance by the light receiving unit. Analyzer of the gas component concentration, characterized in that it comprises an arithmetic unit is provided.

  According to one aspect of the present invention, there is provided a gas component concentration analyzer for analyzing the gas component concentration of the exhaust gas by transmitting laser light through the flue gas generated in the converter and dedusted in the flue. A measuring unit for measuring the flow rate or flow velocity of the exhaust gas, an insertion tube disposed in the flue surrounding a part of the optical path of the laser light, and a purge gas for flowing an inert gas as a purge gas in the insertion tube A supply unit, a light projecting unit that transmits the laser light into the flue, and a light receiving unit that measures the absorbance of the laser light transmitted through the flue by receiving the projected laser light; Based on the measurement result of the absorbance by the light receiving unit, the calculation unit for calculating the gas component concentration and the measurement result of the flow rate or flow velocity of the exhaust gas by the measurement unit, the flow rate of the exhaust gas. And a purge gas control unit that adjusts the flow rate of the purge gas so as to cancel out an error in the analysis result of the gas component concentration calculated by the calculation unit due to fluctuations in flow velocity. Is provided.

  According to one aspect of the present invention, there is provided an exhaust gas recovery facility for exhausting exhaust gas generated in a converter and dedusted to the atmosphere or recovering to a gas holder as fuel gas according to the gas component concentration, From the flue flow through which the exhaust gas flows and connected to the chimney and the gas holder, the gas component concentration analyzer provided in the flue for analyzing the gas component concentration of the exhaust gas, and the analysis result of the gas component concentration When the exhaust gas is determined to be recoverable, the exhaust gas flow path is adjusted so that the exhaust gas is sent to the gas holder, and when it is determined that the exhaust gas cannot be recovered, the exhaust gas is And a recovery control unit for adjusting the flow path so as to be sent to the exhaust gas.

  According to one aspect of the present invention, even when the flow rate of exhaust gas changes, the gas component concentration analysis method, exhaust gas recovery method, and gas component concentration analysis device can accurately measure the gas component concentration of the exhaust gas. And exhaust gas recovery equipment.

It is a schematic diagram which shows the analyzer of the gas component density | concentration which concerns on the 1st Embodiment of this invention. It is a mimetic diagram showing recovery equipment of exhaust gas concerning a 1st embodiment. It is a flowchart which shows the collection | recovery method of the waste gas which concerns on 1st Embodiment. It is a schematic diagram which shows the analyzer of the gas component density | concentration which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the collection | recovery method of the waste gas which concerns on 2nd Embodiment. It is a schematic diagram which shows the modification of the edge part of an insertion tube. It is a graph which shows the relationship between the flow volume of waste gas, and CO density | concentration difference in fixed purge gas flow volume. It is a graph which shows the relationship between the flow volume of waste gas, and CO density | concentration difference in different purge gas flow volume. It is a graph which shows the relationship between the flow volume of waste gas, and the nitrogen (purge gas) flow volume from which a CO concentration difference becomes 0 volume%.

  In the following detailed description, numerous specific details are set forth, illustrating embodiments of the present invention, in order to provide a thorough understanding of the present invention. However, it will be apparent that one or more embodiments may be practiced without such specific details. In the drawings, well-known structures and devices are schematically shown for simplicity.

<First Embodiment>
[Gas component concentration analyzer and exhaust gas recovery equipment]
First, with reference to FIGS. 1-3, the structure of the gas component concentration analyzer 1 and the exhaust gas recovery facility 2 according to the first embodiment of the present invention will be described.
The recovery facility 2 is a facility for recovering exhaust gas generated by blowing, which is an acid feeding refining process in the converter 5. In the blowing of the converter 5, oxygen is mainly blown into the hot metal accommodated in the furnace body 50 from a tuyere (not shown) provided at the bottom of the main lance 51 or the furnace body 50, thereby Carbon and phosphorus inside are removed by oxidation. At this time, gas components such as CO (carbon monoxide) and CO ₂ (carbon dioxide) are generated from the converter 5 as exhaust gas along with the treatment. In blowing, dust containing iron or the like in hot metal is generated, and this dust is contained in the exhaust gas.

The recovery facility 2 includes a flue 20, a water seal tank 21, an induction blower 22, a three-way valve 23, and the analyzer 1.
The flue 20 is a flow path (duct) for exhaust gas, and extends from the furnace port on the upper side of the furnace body 50 (upper side in FIG. 2) to the chimney and the gas holder. The flue 20 includes a first region 201 that extends upward from the furnace port in the vertical direction (vertical direction in FIG. 2), and a second region 202 that is connected to the first region 201 and extends downward in the vertical direction. And a third region 203 connected to the second region 202 and extending in the horizontal direction (left-right direction in FIG. 2). In the first region 201, steam and water flow on the outer peripheral surface of the flue 20 to be cooled, and the heat of the exhaust gas is recovered by the boiler. In the second region 202, a saturator is provided in the flue 20, and water is blown onto the exhaust gas that has passed through the first region 201, whereby the exhaust gas is further cooled, and dust in the exhaust gas is collected with water. Dust removal is performed by being dusted. The third region 203 is divided into two parts in which the exhaust gas cooled and removed in the second region 202 is sent to a chimney or a gas holder, and the exhaust gas path after the analyzer 1 is connected to the chimney and the gas holder. .

The water-sealed tank 21 is a water tank provided to be connected to the lower side of the second area 202 and shuts off the exhaust gas and the atmosphere with dust collection water, and is sprayed on the exhaust gas in the second area 202 to generate dust. The collected dust water is sent from the flue 20. In addition, the collected water sent to the water sealing tank 21 is further sent to a thickener (not shown) via a flow path opened to the atmosphere. In the thickener, the dust contained in the dust collection water is settled and separated by retaining the dust collection water sent from the water sealing tank 21 in the tank.
The induction blower 22 is provided in the middle of the third region 203, sucks exhaust gas through the flue, and sends the exhaust gas to the three-way valve 23.
The three-way valve 23 is provided at the branch point of the third region 203 where the path is divided into the chimney side and the gas holder side. The three-way valve 23 receives the signal transmitted from the analyzer 1 and changes the exhaust gas path to the chimney side or the gas holder side.

The analyzer 1 is a laser analyzer for analyzing the CO gas concentration and the oxygen gas concentration, respectively, and includes a light projecting unit 10, a light receiving unit 11, a pair of insertion tubes 12a and 12b, and a pair of purge gas supplies. Units 13 a and 13 b, a pair of purge gas supply paths 14 and 14 b, an exhaust gas flow measurement unit 15, a calculation unit 16, and a recovery control unit 17.
The light projecting unit 10 includes a semiconductor laser beam irradiation device with a variable wavelength, and projects the laser beam 3 to the light receiving unit 11.

The light receiving unit 11 is provided with a photodetector, and detects the intensity of the laser light 3 projected from the light projecting unit 10 and transmitted through the flue.
The light projecting unit 10 and the light receiving unit 11 are provided in the third region 203 of the flue 20 on the upstream side of the induction blower 22 in the flow direction of the exhaust gas, and the directions facing each other are the extending direction of the flue 20 They are arranged perpendicular to (the front-rear direction in FIG. 1). The light projecting unit 10 and the light receiving unit 11 are provided outside the flue 20, and the laser light 3 having a plurality of wavelengths projected from the light projecting unit 10 is smoked through an insertion tube 12 a provided in the flue 20. The light passes through the passage 20, passes through the flue 20 through the insertion tube 12 b provided in the flue 20, and is projected to the light receiving unit 11. Further, the light projecting unit 10 and the light receiving unit 11 transmit the distinction of the wavelength of the laser light 3 and the detection result of the light intensity to the calculation unit 16 that is electrically connected.

  The pair of insertion tubes 12 a and 12 b are cylindrical members disposed in the flue 20 so as to surround a part of the optical path of the laser light 3. The pair of insertion tubes 12 a and 12 b are respectively connected to the light projecting unit 10 and the light receiving unit 11, and penetrate the side surface of the flue 20 from the light projecting unit 10 and the light receiving unit 11 provided outside the flue 20. Thus, it extends into the flue 20. The pair of insertion tubes 12a and 12b are provided to face each other in a direction orthogonal to the extending direction of the flue 20, and a gap is formed between them by a predetermined distance. Although the edge part distribute | arranged in the flue 20 of a pair of insertion tube 12a, 12b may be a flat end surface shape orthogonal to the axial direction of an insertion tube, it is disclosed by patent document 2 As described above, it is preferable to prevent the intrusion of dust or the like into the tube by making the tip of the insertion tube a notch on the downstream side in the exhaust gas flow direction. In addition, the insertion tube is generally provided in such a manner that a pair of both connected to the light projecting unit 10 and the light receiving unit 11 protrudes into the flue as described above, but only one of them is smoke. It can also be configured to project into the road. Furthermore, a pair of insertion tubes can be configured integrally, and exhaust gas can be introduced into the section from a side opening provided in a predetermined section in the middle of the tube and used for measurement.

  The pair of purge gas supply units 13a and 13b supplies the purge gas 4 at a predetermined flow rate to the pair of purge gas supply paths 14a and 14b, respectively. The purge gas 4 is an inert gas, and nitrogen gas is used in this embodiment. The pair of purge gas supply units 13a and 13b may receive a signal from an electrically connected purge gas control unit (not shown) and supply the purge gas 4 at a known flow rate corresponding to the received signal.

  The pair of purge gas supply paths 14a and 14b are connected to the pair of purge gas supply units 13a and 13b, respectively, and send the purge gas 4 supplied from the pair of purge gas supply units 13a and 13b to the pair of insertion tubes 12a and 12b, respectively. . The purge gas 4 supplied from the pair of purge gas supply units 13a and 13b is sent to the pair of insertion tubes 12a and 12b through the pair of purge gas supply passages 14a and 14b, and then the pair of insertion tubes 12a and 12b. It ejects from the end face in the flue 20.

  The exhaust gas flow measuring unit 15 is a measuring device that measures a gas flow rate or a gas flow velocity, and measures the flow rate or flow velocity of the exhaust gas flowing through the flue 20. In FIG. 1, the case where a flow velocity probe is installed in the flue is schematically shown as an example. However, the method of measuring the exhaust gas flow rate or the exhaust gas flow velocity is not limited to this, for example, in the venturi section provided in the middle of the flue A known method such as a method of measuring the differential pressure can be used. The measurement unit 15 transmits the measurement result of the exhaust gas flow rate to the calculation unit 16 that is electrically connected.

  The calculation unit 16 analyzes the gas component concentration of the exhaust gas based on the detection result of the light intensity of each wavelength of the laser light 3 by the light receiving unit 11 and the measurement result of the exhaust gas flow rate or exhaust gas flow rate by the exhaust gas flow measurement unit 15. Details of the gas component concentration analysis method will be described later. In addition, the calculation unit 16 transmits the analysis result of the gas component concentration (CO concentration and oxygen concentration) to the recovery control unit 17.

  The recovery control unit 17 controls the exhaust gas flow path in the third region 203. Specifically, the collection control unit 17 controls the operation of the three-way valve 23 to control whether the exhaust gas flowing through the third region 203 is subsequently sent to the chimney or the gas holder. Further, the recovery control unit 17 acquires the analysis result of the gas component concentration from the calculation unit 16, and controls the exhaust gas flow path in the third region 203 based on the acquired analysis result.

[Analysis method of gas component concentration and recovery method of exhaust gas]
Next, a gas component concentration analysis method and exhaust gas recovery method according to the first embodiment will be described. In the exhaust gas recovery method according to the first embodiment, exhaust gas generated in the converter 5 is recovered as fuel gas. The exhaust gas is collected according to the processing flow shown in FIG. Note that the processing flow shown in FIG. 3 starts upon the start of blowing in the converter 5.

  As shown in FIG. 3, first, when blowing is started in the converter 5, the generated exhaust gas is diffused into the atmosphere (S100). At this time, the three-way valve 23 is set so that the exhaust gas flow path in the third region 203 is sent to the chimney as an initial position. The exhaust gas generated by blowing is cooled and removed by passing through the first and second regions 201 and 202 of the flue 20, and is sent from the third region 203 to the chimney to be diffused into the atmosphere. If it is flammable, it will burn further. Further, with the start of blowing, supply of the purge gas 4 from the pair of purge gas supply units 13a and 13b to the pair of purge gas supply paths 14a and 14b is started. In the first embodiment, the purge gas 4 is supplied at a constant flow rate that is set in advance so that the exhaust gas does not enter the pair of insertion tubes 12a and 12b. The supply of the purge gas 4 is continued until the blowing is completed. In addition, the flow rate of the purge gas may be changed according to the operating conditions or the like so as to prevent dust and the like from entering the insertion tube.

After a predetermined time has elapsed from step S100, a measurement loop for analyzing the concentration of exhaust gas components and controlling exhaust gas recovery starts (S102). In the first embodiment, the CO concentration and oxygen concentration of the exhaust gas are analyzed as the gas component concentration.
In the measurement loop, first, the exhaust gas flow measurement unit 15 measures the flow rate or flow velocity of the exhaust gas (S104). The measurement result of the flow rate or flow velocity of the exhaust gas is sent to the calculation unit 16.

  Next, the light projecting unit 10 and the light receiving unit 11 measure the light intensities of the laser beams 3 having a plurality of wavelengths transmitted through the exhaust gas in order to measure the absorbance of the exhaust gas (S106). In step S <b> 106, laser light 3 having a plurality of wavelengths is projected from the light projecting unit 10 to the light receiving unit 11. The laser light 3 projected from the light projecting unit 10 passes through the flue 20 through which the exhaust gas flows and is projected to the photodetector of the light receiving unit 11. The light receiving unit 11 measures the light intensity of the received laser beam 3 at other wavelengths having different absorption wavelengths and absorption coefficients of the gas component to be analyzed, and transmits the measurement results to the calculation unit 16.

Further, the calculation unit 16 calculates the absorbance based on the measurement results of the light intensities of the laser beams 3 having a plurality of wavelengths acquired from the light receiving unit 11, and calculates the absorbance and the exhaust gas flow rate acquired from the exhaust gas flow measurement unit 15. Alternatively, the gas component concentration of the exhaust gas is calculated using the measurement result of the flow velocity (S108). In step S108, first, the calculation unit 16 compares the measurement results of the light intensities at a plurality of wavelengths to calculate the absorbance and the temporary gas component concentration. Absorbance can be conveniently expressed by the light intensity ratio (Im / Ir) between the light intensity Im of the laser light 3 at the absorption wavelength of the gas component to be analyzed and the light intensity Ir of the reference laser light having a different wavelength (however, Im / Ir). , Assuming that the light intensity of the two wavelengths is equal). When the difference in absorption coefficient of the gas component to be analyzed at both wavelengths is Δε, and the optical path length in the exhaust gas is L, the temporary gas component concentration C1 and the absorbance (Im / Ir) have the relationship of the following equation (1). is there. Accordingly, the temporary gas component concentration C1 is calculated from the absorbance measurement result (Im / Ir) by the equation (1).
(Im / Ir) = 10 ^{−Δε · C1 · L} (1)

Next, the calculation unit 16 corrects the temporary gas component concentration C1 using a correction coefficient expressed by a function of a preset flow rate or flow velocity of the exhaust gas, thereby obtaining a final exhaust gas component concentration (CO concentration). And oxygen concentration). The correction coefficient η is, for example, a linear function of the exhaust gas flow rate or flow velocity, and is represented by, for example, the following equation (2). In the equation (2), X ₁ is a flow rate of exhaust gas [10 ³ Nm ³ / h], and α ₁ and β ₁ are constants.
η = α ₁ × X ₁ + β ₁ (2)

When not the purge flow rate is constant, to previously obtain a constant alpha ₁ and beta ₁ corresponds to the flow rate of purge gas to be used in advance, depending on the purge gas flow rate actually used above (2) constant alpha ₁ and beta ₁ May be changed to calculate the correction coefficient η. In addition, when the purge gas flow rate is not constant, the correction coefficient η is obtained in advance as a function of both the exhaust gas flow rate and the purge gas flow rate, and the correction coefficient using the measured value of the purge gas flow rate together with the measured value of the exhaust gas flow rate. η may be calculated.

Constant alpha ₁ and beta ₁ is obtained in advance under the condition having various exhaust gas flow _{X 1,} and the ratio of the gas component concentration analysis values _(C ref / C1), the relationship between the exhaust gas flow rate _{X 1 ((C} ref / C1 ) = Α ₁ × X ₁ + β ₁ ). Here, C _ref is the exhaust gas sample taken from the flue in conditions having various exhaust gas flow X _1, due to the high analytical method reliable than laser type analyzer such as a gas chromatograph analyzer, gas component concentration This is the analysis value. C1 is a temporary gas component concentration obtained by the laser analyzer at the timing when the exhaust gas sample is collected.

The finally calculated gas component concentration is calculated by multiplying the provisional gas component concentration C1 by the correction coefficient η, and the calculated gas component concentration (CO concentration and oxygen concentration) is the recovery control unit 17. Sent to.
Since the functional equation of the correction coefficient η and its constant vary depending on the shape of the insertion tube used and the installation conditions in the flue, it is determined according to the installation conditions of the insertion tube used in the actual flue. It is necessary to The correction coefficient η can be approximated by a linear function of the exhaust gas flow rate and the purge gas flow rate as described above, but the function form of η is not necessarily limited to this. For example, η may be approximated by a quadratic function such as the exhaust gas flow rate, or η may be approximated by a function such as a linear function of a ratio value between the exhaust gas flow rate and the purge gas flow rate. Each constant in the case of using each of these function forms is also obtained by organizing data collected according to the function form used in the same manner as in the above case and performing multiple regression analysis or the like.

In the above description, the correction coefficient η is corrected by multiplying the provisional gas component concentration C1 as an example. However, the provisional gas component concentration C1 is corrected to calculate the final gas component concentration. The calculation method at this time is not necessarily limited to this. For example, the final gas component concentration may be calculated by dividing the temporary gas component concentration C1 by the correction coefficient η. In this case, it corresponds to the objective variable in the regression analysis or multiple regression analysis for obtaining each constant used in the functional expression representing the correction coefficient η from the measurement data (in the above example, the ratio of the gas component concentration analysis value (C _ref / C1)) Is changed according to the relational expression between the final gas component concentration and the provisional gas component concentration C1, which represents the correction coefficient η. Furthermore, the final gas component concentration may be calculated by another arithmetic expression that uses the temporary gas component concentration C1, the exhaust gas flow rate (or the exhaust gas flow layer), and the purge gas flow rate and does not use the correction coefficient η. In this case as well, the constant of the arithmetic expression can be determined from the measurement data by multiple regression analysis as exemplified above.

  After step 108, the recovery control unit 17 determines whether the exhaust gas can be recovered based on the acquired CO concentration and oxygen concentration of the exhaust gas (S110). In step S110, the recovery control unit 17 determines whether or not the acquired CO concentration and oxygen concentration of the exhaust gas are equal to or higher than the preset threshold values, and the CO concentration is equal to or higher than the threshold value, and the oxygen concentration is equal to the threshold value. When the concentration is less than the threshold value, it is determined that the gas can be recovered.

If it is determined in step S108 that the recovery is impossible, the recovery control unit 17 controls the three-way valve 23 so that the exhaust gas flowing through the third region 203 is sent to the chimney, thereby reducing the exhaust gas to the atmosphere. It performs (S112).
On the other hand, if it is determined in step S108 that recovery is possible, the recovery control unit 17 controls the three-way valve 23 so that the exhaust gas flowing through the third region 203 is sent to the gas holder, thereby recovering the exhaust gas. (S114).
In the measurement loop of step S102, for example, the above-described steps S104 to S114 are repeatedly performed at predetermined time intervals. In the above description, in order to simplify the description, steps S104 to S114 are described as a series of process flows. However, it is not always necessary to execute all the process steps as a series of processes. For example, an execution loop may be formed for each processing step, and data may be transferred at a timing necessary for each execution loop. When the blowing in the converter 5 is finished, the measurement loop is finished by the interrupt process (S116). Further, when the measurement loop ends, the processing flow of the exhaust gas recovery processing ends.

<Second Embodiment>
[Gas component concentration analyzer and exhaust gas recovery equipment]
Next, the configuration of the gas component concentration analyzer 1 and the exhaust gas recovery facility 2 according to a second embodiment of the present invention will be described with reference to FIG.
The recovery facility 2 is the same as that of the first embodiment shown in FIG.

The analyzer 1 is a laser analyzer, which includes a light projecting unit 10, a light receiving unit 11, a pair of insertion tubes 12a and 12b, a pair of purge gas supply units 13a and 13b, and a pair of purge gas supply paths 14, 14 b, an exhaust gas flow measurement unit 15, a calculation unit 16, a recovery control unit 17, and a purge gas control unit 18.
The configurations of the light projecting unit 10, the light receiving unit 11, the pair of insertion tubes 12a and 12b, the pair of purge gas supply paths 14 and 14b, and the recovery control unit 17 are the same as those in the first embodiment.

The pair of purge gas supply units 13a and 13b is the same as in the first embodiment, but is further electrically connected to the purge gas control unit 18, and receives a signal from the purge gas control unit 18 to adjust the flow rate of the purge gas 4. .
The exhaust gas flow measurement unit 15 is the same as that of the first embodiment, but is electrically connected to the purge gas control unit 18 instead of the calculation unit 16, and transmits the measurement result of the exhaust gas flow rate or flow velocity to the purge gas control unit 18. .

The calculation unit 16 analyzes the gas component concentration of the exhaust gas based on the detection result of the laser beam 3 by the light receiving unit 11. Details of the gas component concentration analysis method will be described later. In addition, the calculation unit 16 transmits the analysis result of the gas component concentration to the recovery control unit 17.
The purge gas control unit 18 calculates the flow rate of the purge gas 4 based on the measurement result of the flow rate or flow rate of the exhaust gas by the exhaust gas flow measurement unit 15, and controls the pair of purge gas supply units 13a and 13b so that the calculated flow rate is obtained.

[Analysis method of gas component concentration and recovery method of exhaust gas]
Next, a gas component concentration analysis method and exhaust gas recovery method according to the second embodiment will be described. In the exhaust gas recovery method according to the second embodiment, exhaust gas generated in the converter 5 is recovered as fuel gas, as in the first embodiment. The exhaust gas is collected according to the processing flow shown in FIG. Note that the processing flow shown in FIG. 5 starts upon the start of blowing in the converter 5 as in the first embodiment.
As shown in FIG. 5, first, when blowing is started in the converter 5, the generated exhaust gas is diffused into the atmosphere (S200). The process of step S200 is the same as step S100 in the first embodiment.

Simultaneously with the start of step S200, a measurement loop for analyzing the gas component concentration of the exhaust gas and controlling the recovery of the exhaust gas is started (S202). In the second embodiment, as in the first embodiment, the CO concentration and oxygen concentration of the exhaust gas are analyzed as the gas component concentration.
In the measurement loop, first, the exhaust gas flow measurement unit 15 measures the flow rate or flow velocity of the exhaust gas as in step S104 of the first embodiment (S204). The measurement result of the flow rate or flow velocity of the exhaust gas is sent to the purge gas control unit 18.

  Next, the purge gas control unit 18 calculates the flow rate of the purge gas 4 from the obtained measurement result of the flow rate or flow rate of the exhaust gas, and sends a control signal so that the purge gas 4 flows from the pair of purge gas supply units 13a and 13b at the calculated flow rate. Make a call (S206). The purge gas control unit 18 calculates the flow rate of the purge gas 4 based on a preset function so that the flow rate of the purge gas 4 increases as the flow rate or flow rate of the exhaust gas increases. Then, the purge gas control unit 18 controls the pair of purge gas supply units 13a and 13b so that the flow rate of the purge gas 4 is calculated. That is, in the measurement loop, the flow rate of the purge gas 4 is adjusted every time step S206 is repeatedly performed.

  In the following description, in order to simplify the description, the control flow of the purge gas flow rate consisting of steps S204 and S206, the measurement flow of the gas component concentration of exhaust gas and the control flow of exhaust gas recovery consisting of the following steps are measured. Although the embodiment implemented as a series of flows constituting a loop has been described as an example, these control flows and measurement flows do not have to be a series of processing flows, and an execution loop is provided for each control flow or measurement flow. It is rather common to configure to form. In any of the embodiments, the supply and control of the purge gas 4 are continuously performed from the start to the end of blowing.

In step S206 of the second embodiment, unlike the first embodiment, for example, a function represented by the following equation (3) is used so as to cancel the error in the analysis result of the gas component concentration due to the fluctuation of the flow rate or flow velocity of the exhaust gas. Is used to calculate the set value of the flow rate of the purge gas 4, and the flow rate of the purge gas 4 is automatically adjusted. In equation (3), Y ₂ is the set value [L / min] of the purge gas flow rate, X ₂ is the exhaust gas flow rate [10 ³ Nm ³ / h], and α ₂ and β ₂ are described later in the description of the embodiments. It is a constant set in such a way.
Y ₂ = α ₂ × X ₂ + β ₂ (3)

When being measured in the exhaust gas flow measuring unit 15 is the exhaust gas flow rate, purge gas flow rate is calculated by the function formula of the exhaust gas flow rate as a variable in place of the exhaust gas flow rate X ₂ in equation (3). Exemplified in the above (3), a function formula of the exhaust gas flow rate X ₂ or the exhaust gas flow rate to derive a set value Y ₂ of the purge gas flow rate and variable, the necessarily (3) a linear function like equation Not limited. If suitable for expressing the relationship between the two, a function form including a quadratic function and other general functions such as an exponential function can be used alone or in combination by addition or multiplication.

At this time, the constants as exemplified by α ₂ and β ₂ in the above equation (3) used in each function form can be obtained as follows, similarly to the method described later in the description of the embodiment. it can. That is, in the apparatus and operating conditions actually used for analyzing the gas component concentration, the purge gas flow rate is changed variously, and the error in the analysis value of the exhaust gas flow rate or the exhaust gas flow rate and the gas component concentration under the same purge gas flow rate condition (other reliability The deviation from the analysis value by the high analysis method) is obtained, and the exhaust gas flow rate X ₂ or the exhaust gas flow velocity at which the error of the analysis value of the gas component concentration becomes 0 at each purge gas flow rate Y ₂ is obtained. The relation between the purge gas flow rate Y ₂ thus obtained and the exhaust gas flow rate X ₂ or the exhaust gas flow velocity at which the error of the analysis value of the gas component concentration becomes 0 is applied to a function form as exemplified in the above equation (3). By performing regression analysis and multiple regression analysis, each constant used in each function form can be obtained.

Next, the light projecting unit 10 and the light receiving unit 11 measure the light intensities of the laser beams 3 having a plurality of wavelengths transmitted through the exhaust gas in order to measure the absorbance of the exhaust gas (S208). Step S208 is the same as step S106 of the first embodiment.
Thereafter, as in the first embodiment, the calculation unit 16 calculates the absorbance based on the measurement results of the light intensities of the laser beams 3 having a plurality of wavelengths acquired from the light receiving unit 11, and calculates the exhaust gas from the calculation result of the absorbance. The gas component concentration is calculated (S210). Unlike the first embodiment, step S210 of the second embodiment does not use the measurement result of the flow rate of the exhaust gas and the measurement result of the flow rate of the purge gas 4 in calculating the gas component concentration. That is, in step S210 of the second embodiment, the gas component concentration is calculated in the same manner as the provisional gas component concentration calculation method in the first embodiment, and the calculated gas component concentration is the final gas component. Concentration.
Thereafter, the calculated gas component concentration is transmitted to the recovery control unit 17.

  In step S210 of the second embodiment, the flow rate of the purge gas 4 is adjusted according to the flow rate or flow rate of the exhaust gas so as to cancel out the error in the analysis result of the gas component concentration due to the fluctuation of the flow rate or flow rate of the exhaust gas. The gas component concentration can be calculated. Here, in the laser analyzer, the purge gas is used for the purpose of preventing the exhaust gas and dust from entering the insertion tube. For this reason, when the flow rate of exhaust gas is small, the flow rate of purge gas may be reduced, and the amount of purge gas used can be suppressed by changing the flow rate of purge gas in accordance with the flow rate of exhaust gas. That is, according to the second embodiment, it is possible to improve the analysis accuracy of the gas component concentration of the exhaust gas and reduce the use cost of the purge gas.

After step 210, similarly to step S110 of the first embodiment, the recovery control unit 17 determines whether exhaust gas can be recovered based on the acquired CO concentration of the exhaust gas (S212).
When it is determined in step S212 that recovery is impossible, the recovery control unit 17 controls the three-way valve so that the exhaust gas flowing through the third region 203 is sent to the chimney, as in step S112 of the first embodiment. By controlling 23, the exhaust gas is diffused into the atmosphere (S214).

On the other hand, when it is determined in step S212 that recovery is possible, the recovery control unit 17 causes the exhaust gas flowing through the third region 203 to be sent to the gas holder, as in step S114 of the first embodiment. The exhaust gas is recovered by controlling the three-way valve 23 (S216).
In the measurement loop of step S202, for example, the above-described steps S204 to S216 are repeatedly performed at predetermined time intervals, similarly to step S102 of the first embodiment. In the above description, in order to simplify the description, steps S204 to S216 are described as a series of process flows. However, it is not always necessary to execute all the process steps as a series of processes, and an execution loop is provided for each process step. It is also possible to configure such that data is transferred at a timing required for each execution loop. When the blowing in the converter 5 is finished, the measurement loop is finished by the interrupt process (S218). Further, when the measurement loop ends, the processing flow of the exhaust gas recovery processing ends.

<Modification>
Although the present invention has been described above with reference to specific embodiments, it is not intended that the present invention be limited by these descriptions. By referring to the description of the present invention, other embodiments of the present invention will be apparent to those skilled in the art, including various modifications along with the disclosed embodiments. Therefore, it should be understood that the embodiments of the present invention described in the claims also include embodiments including these modifications described in the present specification alone or in combination.

For example, in the first embodiment, the final gas component concentration is calculated from the calculated correction coefficient and the temporary gas component concentration in step S108, but the present invention is not limited to such an example. For example, when calculating the gas component concentration in step S108, the final gas component concentration may be calculated by correcting the optical path length used for calculating the gas component concentration. In this case, in step S108, the final gas component concentration can be obtained by calculating the gas component concentration in the same manner as the temporary gas component concentration using the optical path length corrected according to the flow rate of the exhaust gas. The measurement error of the gas component concentration due to the fluctuation of the exhaust gas flow rate is caused by the fact that the optical path length substantially changes due to the fluctuation of the exhaust gas flow rate. At this time, the substantial change amount of the optical path length is a function of the flow rate of the exhaust gas and the purge gas flow rate. When the purge gas flow rate is constant, the optical path length is corrected by, for example, a linear function of the exhaust gas flow rate. The correction function shown is added and used. If X ₁ is the exhaust gas flow rate [10 ³ Nm ³ / h] and the interval between the tips of the pair of insertion tubes, which is normally used as the optical path length, is L ₀ , the corrected optical path length L is, for example, a constant It is represented by the following formula (4) using α ₃ and β ₃ .
L = L ₀ + α ₃ × X ₁ + β ₃ (4)

Here, the constants α ₃ and β ₃ can be obtained by regression analysis or the like from the respective analysis results of the exhaust gas flow rate and the gas component concentration in the same manner as the constant of the equation (2) in the first embodiment described above. Since it differs depending on the shape of the insertion tube to be used, it is necessary to determine in accordance with the installation conditions of the actually used insertion tube and the purge gas flow rate.
Assuming that the temporary gas component concentration calculated from the above equation (1) using the optical path length L ₀ for a certain absorbance is C ₀ , the gas component concentration C ′ calculated using the corrected optical path length L. Is represented by the following equation (5).
C ′ = C ₀ × L ₀ / (L ₀ + α ₃ × X ₁ + β ₃ ) (5)

Therefore, this case may be a gas component concentration C ₀ of the provisional considered to be corrected by multiplying coefficients is advantageous function of exhaust gas flow rate X _1.
When the purge gas flow rate is also a variable, for example, a correction function indicated by a linear function of the exhaust gas flow rate and the purge gas flow rate is added, or a ratio function of the exhaust gas flow rate and the purge gas flow rate is indicated by a linear function. The optical path length is corrected by adding a correction function.

Furthermore, in the first embodiment, nitrogen is used as the purge gas 4, but the present invention is not limited to such an example. The purge gas 4 may be an inert gas and may be another component composition such as argon.
Furthermore, in the first embodiment, the collection control unit 17 is provided in the analyzer 1, but the present invention is not limited to such an example. For example, the recovery control unit 17 that adjusts the flow path of the exhaust gas in the third region 203 may be provided in an apparatus such as a control facility different from the analysis apparatus 1 of the converter 5.

  Furthermore, in the exhaust gas recovery facility according to the present invention, a furnace top oxygen analyzer and a furnace top CO analysis may be further provided as in Patent Document 1. In this case, when determining whether or not the exhaust gas can be recovered, in addition to the analysis result of the analyzer 1, the analysis result by the furnace top oxygen analyzer and the furnace top CO analysis satisfy each predetermined condition. Alternatively, the fuel gas may be recovered as being recoverable.

  Further, in the first and second embodiments, the analyzer 1 analyzes the CO concentration and the oxygen concentration of the exhaust gas as the gas component concentration, but the present invention is not limited to such an example. The analyzer 1 may analyze the concentration of other gas components in the exhaust gas in addition to the CO concentration and the oxygen concentration. In addition, when analyzing the CO concentration and oxygen concentration using a laser gas analyzer, the present invention is applied to the analysis of only one gas component, and the measurement result of the flow rate or flow velocity of the exhaust gas is used to The component concentration may be calculated or the purge gas flow rate may be adjusted. In this case, as a gas component to be analyzed by applying the present invention, it is desirable to select a gas component that is more effective in improving the gas recovery efficiency safely. In this case, in order to improve the gas recovery rate safely, it is preferable to perform analysis with higher accuracy.

  Furthermore, in the first embodiment, the case where the correction coefficient of the gas component concentration linearly changes with respect to the flow rate or flow rate of the exhaust gas is illustrated, and in the second embodiment, the purge gas is changed with respect to the flow rate or flow rate of the exhaust gas. The case where the flow rate of 4 changes linearly, that is, the case where the flow rate can be approximated by a straight line is illustrated, but the present invention is not limited to such an example. For example, when conditions such as the shape of the ends of the pair of insertion tubes 12a and 12b and the shape of the flue 20 are different, the above relationship may not be linear. For this reason, instead of a linear function, other functions such as an exponential function and a quadratic function may be used alone or in combination.

<Effect of embodiment>
(1) The gas component concentration analysis method according to one aspect of the present invention analyzes the gas component concentration of the exhaust gas by transmitting laser light through the exhaust gas in the flue 20 generated in the converter 5 and dedusted. A gas component concentration analysis method that measures the flow rate or flow velocity of exhaust gas and surrounds a part of the optical path of the laser beam 3 and inserts inert gas into the insertion tubes 12 a and 12 b disposed in the flue 20. In the state where the gas is purged as the purge gas 4, the laser beam 3 is transmitted through the flue 20, the absorbance of the transmitted laser beam 3 is measured, and the measurement result of the flow rate or flow velocity of the exhaust gas and the measurement result of the absorbance are used. Then, the gas component concentration is calculated.
According to the configuration of (1) above, even when the flow rate of the exhaust gas passing through the flue 20 changes, the gas component concentration of the exhaust gas can be measured with high accuracy.

(2) In the configuration of (1) above, when calculating the gas component concentration, the temporary gas component concentration calculated from the wavelength characteristic of absorbance is corrected using the measurement result of the flow rate or flow velocity of the exhaust gas. The gas component concentration of the exhaust gas is calculated.
According to the configuration of (2) above, the gas component concentration of the exhaust gas can be accurately measured by simply correcting using the temporary gas component concentration that is the output of the general-purpose laser gas analyzer.

(3) In the configuration of (2) above, the flow rate of the purge gas 4 is further used when correcting the temporary gas component concentration.
According to the configuration of (3) above, the gas component concentration of the exhaust gas can be accurately measured even if the purge gas is variable. For this reason, the use cost of purge gas can be reduced.

(4) In the configuration of (1) above, when calculating the gas component concentration, the optical path length of the laser beam 3 is corrected using the measurement result of the flow rate or flow velocity of the exhaust gas, and the corrected optical path length is used. The gas component concentration is calculated from the wavelength characteristic of absorbance.
According to the configuration of (4) above, the gas component concentration of the exhaust gas can be accurately measured according to the substantial change in the optical path length accompanying the fluctuation of the flow rate of the exhaust gas.
(5) In the configuration of (4), the flow rate of the purge gas 4 is further used when correcting the optical path length.
According to the configuration of (5), the same effect as the configuration of (3) can be obtained.

(6) The gas component concentration analysis method according to one aspect of the present invention analyzes the gas component concentration of the exhaust gas by transmitting the laser beam 3 through the exhaust gas in the flue 20 generated in the converter 5 and dedusted. A gas component concentration analysis method that measures the flow rate or flow velocity of exhaust gas and surrounds part of the optical path of the laser beam 3 with inert gas in the insertion tubes 12a and 12b disposed in the flue. While flowing as the purge gas 4, the laser beam 3 is transmitted through the flue 20, the absorbance of the transmitted laser beam 3 is measured, the gas component concentration is calculated based on the absorbance measurement result, and the absorbance is measured. In this case, the flow rate of the purge gas 4 is adjusted based on the measurement result of the flow rate or flow rate of the exhaust gas so as to cancel the error in the measurement result of the gas component concentration due to the fluctuation of the flow rate or flow rate of the exhaust gas.
According to the configuration of (6) above, even when the flow rate of the exhaust gas passing through the flue 20 changes, the gas component concentration of the exhaust gas can be accurately measured. Further, since the correction of the gas component concentration error is performed by adjusting the purge gas 4, the gas component concentration can be calculated by a method similar to the conventional method. For this reason, application becomes easy also in the existing equipment.

(7) The exhaust gas recovery method according to one aspect of the present invention is an exhaust gas recovery method in which exhaust gas generated in the converter 5 is diffused into the atmosphere or recovered as fuel gas according to the gas component concentration, The exhaust gas generated when starting the blowing in the converter 5 is diffused into the atmosphere, and the gas component concentration of the exhaust gas during the blowing in the converter 5 is set to any one of the above configurations (1) to (6). The analysis is performed using the gas component concentration analysis method, and the exhaust gas is recovered as fuel gas when it is determined from the analysis result of the gas component concentration that the exhaust gas can be recovered.
According to the configuration of (7) above, the gas component concentration of the exhaust gas can be accurately measured even when the flow rate of the exhaust gas passing through the flue 20 changes. For this reason, the collection | recovery efficiency of waste gas can be improved.

(8) The gas component concentration analyzer 1 according to one aspect of the present invention transmits the laser light 3 through the exhaust gas in the flue 20 generated and removed from the converter 5 to thereby determine the gas component concentration of the exhaust gas. A gas component concentration analysis device 1 for analysis, a measurement unit 15 for measuring the flow rate or flow velocity of exhaust gas, and an insertion tube 12a disposed in a flue 20 surrounding a part of the optical path of the laser beam 3 , 12b, purge gas supply units 13a, 13b for flowing an inert gas as a purge gas 4 in the insertion tubes 12a, 12b, and a projection for transmitting the laser beam into the flue 20 by projecting the laser beam 3 A light receiving unit 11 that measures the absorbance of the laser light 3 that has passed through the flue 20 by receiving the projected laser light 3, and a measurement result of the flow rate or flow velocity of the exhaust gas by the measuring unit 15. ,Light receiving section 1 based on the measurement result of the absorbance, and a calculation unit 16 for calculating a gas component density.
According to the configuration of (8) above, the same effect as the configuration of (1) can be obtained.

(9) The gas component concentration analyzer 1 according to one aspect of the present invention transmits the laser light 3 to the exhaust gas in the flue 20 generated in the converter 5 and dedusted, thereby determining the gas component concentration of the exhaust gas. A gas component concentration analysis device 1 for analysis, a measurement unit 15 for measuring the flow rate or flow velocity of exhaust gas, and an insertion tube 12a disposed in a flue 20 surrounding a part of the optical path of the laser beam 3 , 12b, purge gas supply units 13a, 13b for flowing an inert gas as the purge gas 4 into the insertion tubes 12a, 12b, and a laser beam 3 to project the laser beam 3 through the flue 20. By receiving the light unit 10 and the projected laser beam 3, the light receiving unit 11 that measures the absorbance of the laser beam 3 that has passed through the flue 20, and the measurement result of the absorbance by the light receiving unit 11, the gas component concentration Calculate Based on the measurement result of the flow rate or flow rate of the exhaust gas by the calculation unit 16 and the measurement unit 15, the purge gas 4 so as to cancel the error of the analysis result of the gas component concentration calculated by the calculation unit 16 due to the fluctuation of the flow rate or flow rate of the exhaust gas. And a purge gas control unit 18 for adjusting the flow rate of gas.
According to the configuration of (9) above, the same effect as that of the configuration of (6) above can be obtained.

(10) The exhaust gas recovery facility 2 according to one aspect of the present invention disperses the exhaust gas generated in the converter 5 and dedusted to the atmosphere or recovered as a fuel gas in a gas holder according to the gas component concentration. The exhaust gas recovery facility 2 has the flue 20 through which the exhaust gas flows and is connected to the chimney and the gas holder, and the gas component concentration of the exhaust gas that is provided in the flue 20 and analyzes the concentration of the gas component of the exhaust gas When the exhaust gas can be recovered from the gas component concentration analysis device 1 and the gas component concentration analysis result, the exhaust gas flow path is adjusted so that the exhaust gas is sent to the gas holder, and the exhaust gas is recovered. And a recovery control unit 17 that adjusts the flow path so that the exhaust gas is sent to the chimney when it is determined to be impossible.
According to the configuration of the above (10), the same effect as the above (7) can be obtained.

Next, examples performed by the present inventors will be described. In the examples, the gas component concentration of the exhaust gas was analyzed using the same analyzer 1 as that of the second embodiment provided in the exhaust gas recovery facility of the converter having a capacity of 300 t.
In the embodiment, the ends of the pair of insertion tubes 12a and 12b in the flue 20 are provided with the notches shown in the modification of FIG. Other conditions were as follows.
Internal diameter of the flue: 4m
Insertion tube diameter: 40 A (outer diameter 48.6 mm)
Distance between tips of insertion tubes: 0.6m
Length of cut-out portion of insertion tube in exhaust gas flow direction: 16.2 mm
Length in the axial direction of the notch of the insertion tube: 97.2 mm

In the examples, prior to the analysis of the gas component concentration of the exhaust gas, the influence on the measurement of the gas component concentration due to the fluctuation of the flow rate of the exhaust gas was confirmed under the condition that the flow rate of nitrogen as the purge gas 4 was constant. The exhaust gas flow rate during blowing is in the range of 50 to 170 × 10 ³ Nm ³ / h, and tends to be significantly low particularly at the end of blowing. Note that the configurations of the flue 20 and the insertion tubes 12a and 12b were the same as those in the above-described embodiment. FIG. 7 shows the relationship between the exhaust gas flow rate and the CO concentration difference between the laser analyzer and other analyzers when nitrogen at a constant flow rate of 80 L / min is passed through each insertion tube. In FIG. 7, the horizontal axis represents the flow rate of the exhaust gas flowing through the third region 203 measured by the measurement unit 15, and the CO concentration difference on the vertical axis represents the CO concentration from the temporary CO concentration measured by the laser analyzer. This is a deviation value obtained by subtracting the reference value (CO concentration analyzed by an infrared absorption analyzer or the like with high measurement accuracy).

  The reference value of the CO concentration by the infrared absorption analyzer is a value obtained by continuously sucking the exhaust gas after dust removal with dust collection water from the flue and continuously analyzing it with the infrared absorption analyzer. The time delay required for the response of the suction and infrared absorption analyzers was corrected and compared with the analysis value of the laser analyzer to determine the difference between the two. At this time, the reference value of the CO concentration by the infrared absorption analyzer was in the range of 60 to 75% by volume.

  As shown in FIG. 7, it can be seen that the CO concentration difference has a substantially linear correlation with the flow rate of the exhaust gas. That is, as in the first embodiment, the correction coefficient represented by the linear function of the exhaust gas flow rate shown in the equation (2) so that the CO concentration difference shown in FIG. 7 is eliminated from the measured temporary CO concentration. It was confirmed that the CO concentration close to the CO concentration reference value can be calculated by multiplying by the correction.

Since the infrared absorption analyzer is inferior in response speed as compared with the laser analyzer, when the change rate of the CO concentration is large, the difference tends to be large when both analysis values are compared. Therefore, referring to the transition of each exhaust gas analysis value and the transition of the exhaust gas flow rate at each blowing, select a section of 1 minute to several minutes with less fluctuation, and average the values in each section. FIG. 8 shows the result of obtaining data with little variation. The horizontal axis and the vertical axis in FIG. 8 are the same as those in the graph of FIG. 7, and one plot in FIG. 8 corresponds to data of one section during one blowing. Moreover, the average value of the CO concentration reference value by the infrared absorption analyzer of the data shown in FIG. 8 is in the range of 60 to 75% by volume, and the fluctuation range in one section is 5% by volume or less. The plot of the purge N ₂ gas flow rate of 80 Nl / min in FIG. 8 is based on the same blowing data as the plot shown in FIG. Note that the constants α ₁ and β _{1 in the} expression (2) in the first embodiment are the regression lines of the actual values of the exhaust gas flow rate and the CO concentration difference as shown in FIG. 8 if the CO concentration reference value is constant. Can be obtained from

Next, the inventors confirmed the influence of the flow rate of the purge gas 4 on the analysis value by analyzing the gas component concentration by changing the flow rate of the purge gas 4 prior to the analysis of the gas component concentration of the exhaust gas. Note that the configurations of the flue 20 and the insertion tubes 12a and 12b were the same as those in the above-described embodiment. FIG. 8 shows the results of obtaining the relationship between the exhaust gas flow rate and the CO concentration difference for each flow rate of different purge gases (nitrogen) in the same manner as in the case where the purge N ₂ gas flow rate is 80 Nl / min. The straight line in FIG. 8 is a regression line in a plot for each flow rate of nitrogen, and the slope with respect to the exhaust gas flow rate was almost equal at any purge gas flow rate, and thus was determined by regression analysis as being constant regardless of the purge gas flow rate. As shown in FIG. 8, it can be seen that the relationship between the flow rate of the exhaust gas and the CO concentration difference also changes as the flow rate of the purge gas changes.

Further, in order to calculate the constants α ₂ and β ₂ in the equation (3), the flow rate of exhaust gas at which the CO concentration difference becomes 0% by volume with respect to the flow rate of each purge gas 4 was calculated from the regression line shown in FIG. FIG. 9 shows a plot showing the relationship between the flow rate of exhaust gas and the flow rate of purge gas 4 at which the CO concentration difference is 0% by volume, and the regression line obtained from the regression line of FIG. As shown in FIG. 9, it was confirmed that the flow rate of the purge gas 4 at which the CO concentration difference becomes 0% by volume changes linearly with respect to the exhaust gas flow rate. And from this result, when the constants α ₂ and β ₂ in the equation (3) were calculated, α ₂ = 0.77 and β ₂ = 0.099 were obtained.

In the examples, the calculated constants α ₂ and β ₂ were used to analyze the gas component concentration of the exhaust gas as in the second embodiment. In the example, as a comparative example, as in the conventional analysis method, the purge gas 4 is flowed at a constant flow rate of 80 L / min in the same manner as the temporary gas component concentration analysis method of the first embodiment. The CO concentration was analyzed using the distance between the tips of the insertion tubes as the optical path length.

  The analysis accuracy was evaluated using the result of gas chromatograph analysis of the gas component concentration of the exhaust gas sample collected from the flue as a reference value. The exhaust gas sample is collected from the suction pipe provided on the upstream side of the flue analyzer 1 in the vicinity of the flue gas by sucking in about 10 seconds per minute during blowing, and the laser analyzer at the collection timing. The exhaust gas analysis values obtained from the above were compared using the gas chromatographic analysis values of the collected exhaust gas samples as reference values. Therefore, in this case, unlike the case where the analysis value of the infrared analyzer is used as a reference value, there is no problem that the analysis response is delayed.

  In the comparative example, as a result of investigating the variation (square root σ of the mean square value of the difference) of the difference between the analyzed CO concentration and the CO concentration reference value, it was confirmed that the variation was σ = 5.5% by volume. On the other hand, as a result of investigating the variation of the difference between the CO concentration analyzed in the example and the CO concentration reference value, the variation is σ <1% by volume, and according to the gas component concentration analyzing method according to the second embodiment, It was confirmed that the gas component concentration of the exhaust gas can be accurately measured even when the flow rate of the exhaust gas changes.

  In the above description, the case where the analysis target of the laser analyzer is CO gas has been described. However, the influence of the exhaust gas flow rate and the purge gas flow rate on the analysis value should be evaluated in the same manner even when the exhaust gas oxygen concentration is the analysis target. Can do. Also in this case, as in the case of CO gas, it was confirmed that the analysis accuracy was improved by correcting the analysis value based on the measured value of the exhaust gas flow rate and adjusting the purge gas flow rate based on the measured value of the exhaust gas flow rate. However, since the oxygen concentration in the exhaust gas during blowing is generally very low, it is difficult to evaluate the direct effect on the analytical value based on the fluctuation in the exhaust gas flow rate during blowing, This can be replaced by evaluating the influence on the analysis value based on the estimation or estimating the influence on the concentration of other gas components during blowing in the same apparatus.

DESCRIPTION OF SYMBOLS 1 Analyzer 10 Light projection part 11 Light-receiving part 12a, 12b Insertion tube 13a, 13b Purge gas supply part 14a, 14b Purge gas supply path 15 Exhaust gas flow measurement part 16 Calculation part 17 Recovery control part 18 Purge gas control part 2 Exhaust gas recovery equipment 20 Smoke Road 201 1st area | region 202 2nd area | region 203 3rd area | region 21 Water-sealed tank 22 Induction fan 23 Three-way valve 3 Laser light 4 Purge gas 5 Converter 50 Furnace body 51 Main lance

Claims (10)

A gas component concentration analysis method for analyzing a gas component concentration of the exhaust gas by transmitting laser light through the flue gas generated in a converter and dedusted in a flue,
Measuring the flow rate or flow velocity of the exhaust gas,
The laser that passes through and transmits the laser light into the flue in a state where an inert gas flows as a purge gas in an insertion tube disposed in the flue surrounding a part of the optical path of the laser light Measure the light absorbance,
A gas component concentration analysis method, wherein the gas component concentration is calculated based on a measurement result of the flow rate or flow rate of the exhaust gas and a measurement result of the absorbance.   When calculating the gas component concentration, the temporary gas component concentration calculated from the wavelength characteristic of the absorbance is corrected by using the measurement result of the flow rate or flow velocity of the exhaust gas, so that the gas component concentration of the exhaust gas is corrected. The gas component concentration analysis method according to claim 1, wherein the gas component concentration is calculated.   3. The gas component concentration analysis method according to claim 2, further comprising using a flow rate of the purge gas when correcting the temporary gas component concentration.   When calculating the gas component concentration, the optical path length of the laser beam is corrected using the measurement result of the flow rate or flow velocity of the exhaust gas, and the gas component is calculated from the wavelength characteristic of the absorbance using the corrected optical path length. The gas component concentration analysis method according to claim 1, wherein the concentration is calculated.   The gas component concentration analysis method according to claim 4, further comprising using a flow rate of the purge gas when correcting the optical path length. A gas component concentration analysis method for analyzing a gas component concentration of the exhaust gas by transmitting laser light through the flue gas generated in a converter and dedusted in a flue,
Measuring the flow rate or flow velocity of the exhaust gas,
The laser that passes through and transmits the laser light into the flue in a state where an inert gas flows as a purge gas in an insertion tube disposed in the flue surrounding a part of the optical path of the laser light Measure the light absorbance,
Based on the measurement result of the absorbance, the gas component concentration is calculated,
When measuring the absorbance, the flow rate of the purge gas is adjusted based on the measurement result of the flow rate or flow rate of the exhaust gas so as to cancel the error in the analysis result of the gas component concentration due to fluctuations in the flow rate or flow rate of the exhaust gas. A method for analyzing a gas component concentration. According to the gas component concentration, the exhaust gas generated in the converter is dissipated into the atmosphere or recovered as fuel gas,
Dissipate the exhaust gas generated when starting blowing in the converter to the atmosphere,
During the blowing in the converter, the gas component concentration of the exhaust gas is analyzed using the gas component concentration analysis method according to any one of claims 1 to 6,
An exhaust gas recovery method, wherein the exhaust gas is recovered as the fuel gas when it is determined from the analysis result of the gas component concentration that the exhaust gas can be recovered. A gas component concentration analyzer for analyzing the gas component concentration of the exhaust gas by transmitting laser light through the flue gas generated in the converter and dedusted in the flue,
A measuring unit for measuring the flow rate or flow velocity of the exhaust gas;
An insertion tube disposed in the flue surrounding a part of the optical path of the laser beam;
A purge gas supply section for flowing an inert gas as a purge gas into the insertion tube;
By projecting the laser beam, a projecting unit that transmits the laser beam into the flue,
By receiving the projected laser light, a light receiving unit that measures the absorbance of the laser light transmitted through the flue,
A calculation unit that calculates the gas component concentration based on a measurement result of the flow rate or flow rate of the exhaust gas by the measurement unit and a measurement result of the absorbance by the light receiving unit. Analysis equipment. A gas component concentration analyzer for analyzing the gas component concentration of the exhaust gas by transmitting laser light through the flue gas generated in the converter and dedusted in the flue,
A measuring unit for measuring the flow rate or flow velocity of the exhaust gas;
An insertion tube disposed in the flue surrounding a part of the optical path of the laser beam;
A purge gas supply section for flowing an inert gas as a purge gas into the insertion tube;
By projecting the laser beam, a projecting unit that transmits the laser beam into the flue,
By receiving the projected laser light, a light receiving unit that measures the absorbance of the laser light transmitted through the flue,
From the measurement result of the absorbance by the light receiving unit, a calculation unit for calculating the gas component concentration,
Based on the measurement result of the flow rate or flow rate of the exhaust gas by the measurement unit, the flow rate of the purge gas so as to cancel the error in the analysis result of the gas component concentration calculated by the calculation unit due to the fluctuation of the flow rate or flow rate of the exhaust gas A purge gas control unit for adjusting
A gas component concentration analyzer comprising: Exhaust gas that is generated in the converter and removed from the dust according to the concentration of the gas component is released to the atmosphere or recovered to the gas holder as fuel gas.
A flue connected to the chimney and the gas holder;
The gas component concentration analyzer according to claim 8 or 9, which is provided in the flue and analyzes the gas component concentration of the exhaust gas.
From the analysis result of the gas component concentration, when it is determined that the exhaust gas can be recovered, the exhaust gas flow path is adjusted so that the exhaust gas is sent to the gas holder, and it is determined that the exhaust gas cannot be recovered. A recovery control unit for adjusting the flow path so that the exhaust gas is sent to the chimney;
An exhaust gas recovery facility comprising:

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