MXPA00004640A - Method and apparatus for off-gas composition sensing - Google Patents

Abstract

An apparatus and method for non-intrusive collection of off-gas data in a steelmaking furnace (100) includes structure and steps for transmitting a laser beam (300) through the off-gas produced by a steelmaking furnace, for controlling the transmitting to repeatedly scan the laser beam through a plurality of wavelengths in its tuning range, and for detecting (400) the laser beam transmitted through the off-gas and converting (600) the detected laser beam to an electrical signal. The electrical signal is processed to determine characteristics of the off-gas that are used to analyze and/or control the steelmaking process.

Description

METHOD AND APPARATUS FOR DETECTING THE COMPOSITION OF DETACHMENT GAS FIELD OF THE INVENTION The present invention is concerned generally with improvements in steelmaking and more particularly with improvements in the measurement of dynamic characteristics of the process in a steelmaking process. .

BACKGROUND OF THE INVENTION [0002] Conventional control technology in the steelmaking industry relies on static computer models, for example, computer models of heat and direct power and energy balance. The composition and weight of the starting materials (for example, first melting iron, waste steel, oxygen, alkaline fluxes, etc.) are introduced to the model and the oxygen flow rate and blowing time are calculated using the model . Due to the unknown composition of the waste steel, significant inaccuracies occur to obtain the desired carbon end point concentration and melting temperature in the final steel product. However, no practical real-time method is commercially available to verify the process characteristics of the steelmaking process and by REF .: 28257 consequently no dynamic control of a process can be carried out. The non-availability of real-time process verification and dynamic process control cause significant safety and efficiency problems for current steelmaking processes such as the basic oxygen process. This process combusts the oxygen with the carbon contained in the molten metal to transform the molten metal to steel. Safe and efficient transformation requires that process variables be controlled to maintain certain process characteristics (for example, temperature and concentrations of CO, C02 and H20) at preferred or optimal values. Since there is no real-time online method to measure or verify these process characteristics at this time, dynamic adjustments can not be made to ensure maximum safety and efficiency. More particularly, current commercial methods for producing steel using the basic oxygen process involve transforming the starting materials containing a relatively high content (up to about 4% by weight) by high speed oxygen blowing to the starting materials. in a batch process called a "warm up". Oxygen is combusted with the carbon contained in the starting materials to decrease the carbon content, to result in carbon containing steel at levels of 0.03 to 0.6% by weight, depending on the alloy desired. The starting materials include molten metal and alkaline flux (collectively referred to as the "bath") and during the steelmaking process form molten and slag phases in an oven. The process is carried out in a basic oxygen furnace (BOF) that includes a large container with a refractory lining to contain the bath, an oxygen lance to blow oxygen into the bath, and exhaust ducts to separate the gases produced by the oxygen process. steel fabrication These gases are collectively referred to as the release gas. One of the main gases produced by the process is carbon monoxide (CO) - the primary reaction product of oxygen and carbon. There are a variety of schemes to further react this CO with oxygen before leaving the furnace, to form carbon dioxide (C02). This post-combustion reaction of CO and oxygen is highly exothermic and therefore releases heat to the slag and melt phases in the furnace. This additional heat accelerates the steel conversion process. A significant problem with commercial steel manufacturing is to make efficient the use of CO, that is, to efficiently control the post-combustion of CO, which requires proper control of the oxygen flow rate. If insufficient oxygen is injected, then the maximum effective use of CO is not obtained. On the other hand, if too much oxygen is injected, then the process is not cost effective because the oxygen is wasted and the release gas becomes too hot, detrimentally affecting the refractory lining and the exhaust duct walls. Conventionally, post-combustion of CO is verified in a time-averaged manner using commercially available mass spectrometry (MS) or non-dispersive infrared absorption (NDIR) methods. These methods require that a sample of the release gas be extracted, cooled and analyzed and therefore there is a significant time delay in data acquisition. Some indication of the post-combustion gas concentration can also be derived by checking the wall temperatures and the cooling water in the exhaust duct using standard thermocouple technology. However, this technique is severely limited in sensitivity, accuracy and response time. This lack of on-line, real-time measurement of CO and C02 concentrations in the release gas prevents efficient control of oxygen flow velocity in conventional steelmaking processes to ensure optimal CO afterburning. Another major problem with current commercial steelmaking methods is the lack of an online method to provide continuous data, in real time, regarding the carbon content of the metal. In many commercial steel mills, the concentration of the carbon end point is determined by stopping the process at the predicted end point, extracting a sample of the molten steel and carrying out an off-line chemical analysis. Another technique involves using a "detector lance" technology that requires a water cooled lance equipped with a disposable oven detector to be lowered. The disposable detector is immersed in the liquid steel near the predicted end point of the oxygen blowing, a metal sample is extracted and the cooling curve of the sample is measured. Then this cooling curve can be correlated with the carbon concentration in the steel. For example, U.S. Patent No. 3,720,404 shows the use of a sample lance. Both of these methods produce only one data point per heating instead of continuous data. Another technique is described in WO 92/02824, which involves extracting a gas sample, separating the water vapor and then analyzing the gas in a gas analyzer using gas chromatography or infrared absorption to determine the release gas composition. In another context, as described in EP 0 768 525 A2, a species of the gas phase can be detected in the effluent of the semiconductor processing chamber by using a laser beam to carry out absorption spectroscopy. However, this technique is directed to the measurement of a single absorption line at a particular desired wavelength. Other methods for carbon endpoint verification use MS or NDIR absorption methods to determine the CO and C02 concentrations in the exhaust gas after it has been cooled and the particles have separated. These methods require the use of a release gas treatment system to treat the gas and such a system requires expensive maintenance. As a result of the lack of continuous data, steelmakers sometimes resort to a technique in which a heating is "blown" to ensure that the molten metal has been properly decarbonized. The "blowing" technique uses excess oxygen to reduce the concentration of carbon in the melt to the lower limit of the desired range, that is, 0.03% by weight. After the container is capped and the steel is transferred to a ladle, the carbon concentration is adjusted back to the desired level by adding material in the ladle. However, this process is inefficient for several reasons. First, excess oxygen is used to ensure complete carbon oxidation in the melt, necessitating additional expense. Second, the use of excess oxygen causes the iron in the molten bath to begin to oxidize when the dissolved carbon has been reduced to very low concentrations. This oxidation results in a loss of iron, which must form a portion of the commercial product, to the iron oxide that ends up in the slag phase. Finally, the blowing process requires the expense of unnecessary additional processing time, thus reducing the performance in the industrial process and consequently increasing the costs and decreasing the benefits. Another significant problem with current steelmaking methods is the creation of a highly reactive scum slag layer when certain combinations of hot metal chemistry and alkaline flux additions are used, which causes the ejection of large quantities of liquid slag from the BOF vessel during oxygen blowing (referred to as "slope"). This "slope" causes an accumulation of undesirable rapid slag in the mouth of the container and exhaust hood surfaces and an accumulation of the bottom of the bucket increased on the lance. The "slope" can be controlled by adjusting the parameters of the lance (for example, the height of the lance above the bath and the oxygen flow rate) but this is difficult to obtain automatically, since the techniques of manufacturing Current steel can not detect the amount of liquid slag that is expelled from the furnace. Still another significant difficulty with current steelmaking methods results from the presence of a large amount of water in the furnace. A large amount of water in the furnace causes the rapid formation of molecular hydrogen in the melt surface, thereby creating a greater safety hazard due to the risk of an explosion. The presence of excess water can be caused by undesirable leakage of cooling water from a water-cooled oxygen lance or water-cooled release gas discharge conduits. Conventionally, the potential for hydrogen formation in the steel conversion furnace is determined by verifying the flows of water cooling water and output through an oxygen lance and an exhaust hood system. Large discrepancies or sudden changes in flow rates could indicate dangerous leaks to the oven container. However, while the verification of the water flow can indicate the source of water that can cause dangerous levels of hydrogen, this method does not indicate the levels of hydrogen actually present and therefore this method does not offer appropriate safety measures against explosions. . In an effort to address the above limitations of the conventional verification technique, research has led to methods for taking gas samples near the mouth of the furnace using water cooled extraction probes. Then the extracted gas is analyzed, either with Fourier transform infrared spectroscopy (FTIR) or mass spectrometry. The FTIR method provides a relatively real-time response to measure the concentration of the gas phase, compared to the methods described above. However, an extraction probe has a limited life due to its location above the mouth of the furnace. In addition, the temperature of the release gas is measured in this technique by a thermocouple located in the extraction probe and such thermocouples have slow response times. A) Yes, an improved verification method is needed that can provide continuous real-time data about the characteristics of the release gas using a non-intrusive, reliable method.

BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to provide an improved method and apparatus for verifying dynamic process characteristics in a manufacturing process. In particular, it is an object of the invention to provide a non-intrusive method for obtaining real-time data about the characteristics of the release gas to allow the analysis and / or dynamic control of a steelmaking process. According to a first aspect of the invention, means (or a step) are provided for transmitting a laser beam through the release gas produced by a steel fabrication furnace, having a range of wavelength tuning of the laser beam. Means (or a step) are also provided to control the transmission to repeatedly scan the laser beam through a preset continuous range of wavelengths in its tuning range, together with means (or a stage) to detect the beam of laser transmitted through the release gas and to convert the detected laser beam to an electrical signal. The preset wavelength range includes at least two absorption lines of one or more gaseous phase species in the release gas. In accordance with another aspect of the invention, means or steps are provided for processing the electrical signal to determine at least one characteristic of the release gas in the steelmaking furnace. According to yet another aspect of the invention, the transmission means comprise a tunable diode laser arranged to transmit a laser beam through the release gas produced by the steelmaking furnace and the control means comprise a circuit of control electrically connected to the laser of the tunable diode to provide an injection current to the tunable diode laser, the control circuit varies the injection current provided to the laser, in such a way that the laser emits a laser beam whose wavelength is repeatedly scanned through the preset wavelength range. The apparatus may also include a computer or computer that receives and processes the electrical signal to determine at least one characteristic of the release gas. In addition, the control circuit can be constructed to vary the injection current to modulate the wavelength of the laser beam while scanning the laser beam through the plurality of wavelengths and the detector can include an amplifier. of fixation to detect a harmonic signal of the modulated laser beam. Additional objects and aspects of the present invention will become apparent to those of ordinary skill in the art from the detailed description of the preferred embodiments, which are discussed later herein, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing a configuration of the present invention suitable for a basic oxygen furnace. Figure 2 is a cross-sectional view of the basic oxygen furnace shown in Figure 1 taken along line II-II. Figure 3 is a schematic view showing the components of a laser source module. Figure 4 is a schematic view showing the components of a detector module. Figure 5 is a graph showing the measured transmittance values and calculated as a function of the wave number. Figure 6 is a graph showing the laser transmittance and temperature values as a function of the elapsed blow time. Figure 7 is a graph showing the values of the laser transmittance ratio and absorbance as a function of the elapsed blow time. Figure 8 is a graph showing the absorbance in H20 as a function of the elapsed blow time. Figure 9a is a graph of a direct absorption spectrum measured experimentally of CO and water vapor in the laboratory. Figure 9b is a graph of the second harmonic spectrum measured experimentally and a second calculated harmonic spectrum of the spectrum of Figure 9a. Figure 10a is a graph showing the transmittance values calculated as a function of the wave number. Figure 10b is a graph showing the transmittance values of the second harmonic calculated from the graph of transmittance values shown in Figure 10a and also shows the transmittance values of the second harmonic measured. Figure 11 is a graph showing the values of the peak carbon dioxide intensity ratio as a function of the elapsed blow time.

Figure 12 is a graph showing the ratio of the peak intensity values of carbon monoxide and carbon dioxide as a function of the elapsed blow time. Figure 13 is a graph showing the signal of the release gas emission intensity (upper curve) and the signal intensity 2f (lower curve) as a function of the elapsed blow time.

DESCRIPTION OF THE PREFERRED MODALITY The present invention is a non-intrusive optical detector system. This system verifies the dynamic process characteristics of a steelmaking process by measuring the characteristics of the release gas produced by a steelmaking furnace. This is accomplished by forwarding a tunable diode laser beam through the release gas while scanning the laser beam through a range of wavelengths and detecting the beam with an infrared optical receiver module. Then the resulting signal is processed to analyze the laser transmittance and absorption intensities that indicate process characteristics, such as CO and C02 concentrations, temperature, carbon endpoint level (ie, carbon content) "slope" of the oven and concentration of water vapor. In general, an optical detector system according to the present invention comprises four distinct sections: (1) a tunable laser source (with a module of appropriate electronic components), (2) a detector module, (3) a path optics from the laser source to the detector module, which passes through the release gas produced by a steelmaking furnace, for example a basic oxygen furnace (BOF) and (4) an acquisition / display / output module of data . The structure of a preferred embodiment of the present invention is described with respect to Figures 1 to 4, followed by a description of the preferred embodiment. Although the preferred embodiment is described with reference to a basic oxygen furnace, the invention is not limited to such an application. Rather, the invention is generally applicable to the analysis of stripping gas streams and to the control of steelmaking processes, in which an optical line of sight can be made available for emission of the laser beam. In addition to basic oxygen furnaces, other examples include electric arc furnaces and bottom-blown oxygen furnaces. Figure 1 shows the deployment of the invention suitable for a basic oxygen furnace 100 having a mouth 105. The furnace is surrounded by shields or heat shields 110 and 120. An exhaust hood 130 is positioned near the mouth 105 of the oven 100 (for example, separated by a gap of approximately 0.9144 m (3 feet)) to collect the release gas. A vertically adjustable oxygen spear 140 is insertable into the furnace 100 to inject oxygen into the furnace. As shown in Figure 1, an optical path 200 located just above the mouth of the furnace is linked to a tunable laser source 300 and an infrared signal detector module 400, which are respectively mounted behind shields or thermal shields 110 and 120 on opposite sides of the furnace 100. Holes are provided in the thermal shields 110 and 120 to provide a path of the laser beam between the laser source 300 and the detector module 400. In the preferred embodiment these holes have a diameter of about 7.62 cm (3 inches) but the size is not critical. A module 500 of electronic components is disposed on the side of the heat shield 110 adjacent to the laser source 300. The laser source 300 and the electronic components module 500 are interconnected by appropriate electric cables 550C and the detector module 400 and the module 500 of electronic components are connected by electrical cables 550b and 550a respectively to a data acquisition / display / output module 600 which are located remotely. Figure 2 is a cross-sectional view of the furnace 100 taken along the sectional line II-II shown in Figure 1. As shown in Figure 2, the optical path 200 is displaced from the center of the furnace to one side of the oxygen lance 140. Further details of the laser source, the detector module and the acquisition / display / output data system are discussed with respect to Figures 3 and 4. As shown in Figure 3, the laser source 300 includes two infrared lasers tunable 310 and 315. Lasers 310 and 315 are similar in their electrical and optical characteristics. Laser 310 is actively used in gas release measurements while laser 315 is reserved as a spare. The laser to be used is selected by computer control (discussed below with respect to module 500 of electronic components) and the path of the beam is determined by the presence or absence of a separable mirror 320. In the preferred embodiment, each of the lasers 310 and 315 is capable of at least a spectral resolution of 0.01 cm "1 at a wave number of 1900 to 2200 cm" 1 (4.55 to 5.26 μm). In service, the laser that is used is configured to work in a range of tuning that is narrower than its possible operating range, for example 2111 to 2115 cm "1. In addition, by selecting the optimum tuning range for other types of For steelmaking processes or for determining gas release characteristics other than those discussed hereinafter, the preferred embodiment may be adapted for use in such other types of steelmaking processes or for determining other characteristics of the release gas Thus, lasers suitable for operating in the wider range of 1700 to 2500 cm "1 (4.0 to 5.88 μm) can be used to provide greater flexibility in the selection of an appropriate tuning range. In the preferred embodiment, lasers 310 and 315 are commercially available lead-diode-diode lasers that emit extremely narrow line width radiation (0.0005 cm "1) in the mid-infrared region, such as a laser model L5621 manufactured by Laser Photonics Inc., Andover, MA These lasers are continuously tunable in a range of approximately 2 to 4 cm "1 when adjusting the injection current of the diode. These are class 1 non-dangerous lasers. Associated with lasers is an evacuable Dewar box 330 suitable for being cooled to the temperature of liquid nitrogen. The laser outputs of the Dewar box 330 are divergent infrared beams and accordingly a lens (350a, 350b) is provided in each beam path to collimate the respective beam. Lenses 350a and 350b are calcium fluoride lenses of focal length f / 1, 3.81-cm (1.5 inches). Mirrors 355a, 355b, 355c and 355d are also provided to direct the laser beam, mirror 355d is a remotely operated mirror that is adjustable to alter the position of the beam path through the furnace release gas. A continuous line in Figure 3 of the laser 310 illustrates the trajectory of the tunable diode laser (TDL) beam. Since the TDL emits the laser at an infrared wavelength therefore is invisible, a visible alignment beam is transmitted along the line of sight of TDL to aid in fast and accurate alignment of the TDL beam with the module detector during the installation of the detector. The alignment beam is generated by a visible alignment laser 360 and is guided by mirrors 356a and 356b to the second surface of a narrowband optical filter 370 in the path of the TDL beam. The infrared TDL beam and the visible laser beam are combined on the second surface of the filter 370 to produce precisely colinear, stable laser beams. A dashed line in Figure 3 illustrates the path of the visible laser beam of the laser 360 to the beam combining filter 370. As shown in Figure 3, a reference beam is provided by inserting a calcium fluoride window 375 into the TDL beam to serve as a beam splitter. Window 375 directs approximately 5 to 10% of the power of the incident laser beam, via a mirror 378, through a gas cell 380 filled with CO at low pressure (approximately 0.0528 atmospheres (40 torricellis)). The beam exiting from the gas cell 380 is focused by a calcium fluoride lens 382 on an indium antimonide infrared reference detector 385 (InSb) or other suitable material that emits a detection signal that is amplified by an amplifier 386. A characteristic absorption pattern of narrow absorption lines is produced as the TDL is scanned through its injection current tuning range. This distinctive configuration is used to verify that the temperature tuning of the diode laser is set correctly and that the current tuning range of the desired diode is scanned. The components of the laser source 300 are enclosed in a jacket 390 to provide appropriate environmental control. The envelope 390 is hermetically sealed to prevent the entry of dust into the envelope. The enclosure or envelope consists of a double-walled water jacket 392 for cooling purposes, with additional thermal insulation 393 mounted on the outside. The internal components of the laser source 300 are further cooled by a stream of cold, dry air, by a mechanism (not shown) that creates a positive pressure inside the envelope or envelope. Cooling water and cold dry air are provided by utilities in the steelmaking plant. The envelope 390 has a window 395 composed of calcium fluoride or some other suitable infrared transmitter material mounted on a wall to allow TDL beam output. The window 395 has an antireflection coating for the wavelength range in which the TDL is put into operation, to prevent the formation of interference bands ("etalons") in the detected TDL signal. The external surface of the window is purged with air, instrument-air by a mechanism that is not shown to prevent the accumulation of dust and debris on the surface. A motor-driven plug 397 is provided on the outside of the wrapper or enclosure 390 to protect the surface of the window 395 when no measures are taken. The motor-driven shutter 397 is driven by a motor 398 and can be put into operation either manually or under computer control. To provide a stable base laser source 300, it is mounted on a plate (not shown) composed of aluminum or a steel honeycomb base plate of sufficient thickness (at least 2.54 cm (1 inch)) to provide stability for the optical components mounted within the envelope 390. The base plate is insulated and mounted firmly on a platform adjacent to the release gas stream. The mounting platform must be sufficiently rigid to support the laser source 300 and must be protected by thermal shields to minimize the radiative and convective heat loads generated by the steelmaking process and the release gas stream. The electronic component module 500 (shown in Figure 1) contains standard electronic components necessary to control and stabilize the output of the tunable diode laser. Additional components include power supplies for various components in the laser source 300 (visible diode alignment laser 360, remote operated mirror 355d, reference detector amplifier 386 and shutter motor 398). These components are remotely controlled by the data acquisition / display / output module 600 to energize the components of the laser source in accordance with the synchronization or timing of the measurements to be made. The module 500 of electronic components is cooled and purged by dry air by a mechanism that is not shown. The cables connecting the electronic component module 500 to the laser source 300 and the data acquisition / display / output module 600 pass through two holes in the electronic components module case. These holes are used as an outlet for the dry purge air, also for similar holes in the laser source and detector modules. As shown in Figure 1, the laser beam passes through the release gas in the BOF 100, adjacent to the oxygen lance 140. The absorption of the laser beam varies as a function of the wave number and the individual absorption lines that are due only to the gaseous phase molecules excited vibrationally in the release gas can be verified by the detector module 400. In this way, inaccuracies due to the optical absorption caused by the CO, C02 and H20 molecules outside the hot zone along the optical line of sight are avoided when calculating gas concentrations and temperatures. In addition to the molecular absorption along the optical path the laser beam can be severely attenuated in its passage through the release gas due to the scattering caused by the very large number of small particles entrained in the gas flow. This attenuation may necessitate the use of path shortening devices for some applications. The path shortening devices may comprise opposed tubes that extend to the flow of release gas over a short distance along the line of sight of the laser beam. The tubes are purged with a flow of either air or some other inert gas and act to shorten the length of the optical path through the particle-laden release gas. Since the path shortening devices do not contain optical components, they can be formed from inexpensive materials and are considered as disposable products or articles in the case of sudden failures due to the accumulation of slag or impact damage from the flying debris. In addition to absorption and attenuation, the additional optical interface in the detector module 400 is generated by fluctuating broad band emissions of particles and gas molecules in the release gas stream. In addition, turbulence within the stripping gas stream and large thermal differentials along the optical path cause the transmitted laser beam to be directed in a random fashion as it enters the detection module 400. Thus, a highly sensitive configuration is required for the detection module 400 to properly detect the transmitted laser beam very weakly. Figure 4 shows the structure of a preferred embodiment of an infrared signal detector module 400. As shown in Figure 4, the components of the detector module are housed in a hermetically sealed, water-jacketed enclosure 410, similar to the enclosure or shell described for the laser source 300. The envelope 410 provides cooling and environmental control for the components of the detector module. The enclosure is mounted on a base plate (not shown) similar to that described for the laser source 300, to provide a stable base for the components of the detector module. A window 430 of calcium fluoride having an antireflection coating is provided in a wall of the envelope 410. The window 430 is used to transmit the TDL beam to the detector module where it also serves to seal the module against intrusion of hot gases and dust. Similar to the 395 advantage of calcium fluoride from the laser source, an antireflection coating reduces the formation of etalons in the detected signal and the outer surface of the window 430 is purged with air from dry instruments by a mechanism that is not shown, to prevent the accumulation of dust particles on its surface. A shutter 435 driven by a motor 437 is provided to protect the window 430 when no measurements are to be made. Mirrors 440a and 440b are provided to guide the laser beam entering the detector module to an InSb detector 450 or other suitable material. The detector 450 has a detector surface of 1 mm in diameter. One or more openings 460a are provided, 460b along the line of sight within the detector module to physically block light outside the unwanted axis that strikes the detector 450, also as to decrease the thermal background noise and experimental noise. A 470 rapid calcium fluoride lens (ie, low f number) is used to focus the laser beam transmitted on the surface of the detector. In the preferred embodiment, a lens having a number of f of 1 is used. This high pickup efficiency and resulting small image size reduces the signal loss due to the laser beam addressing as it traverses the stripping gas. A combination of narrowband optical filters 480a, 480b is placed immediately in front of the detector 450 such that the resulting filter bandpass is centered around the optimum laser tuning range. This mimics unwanted wide band light such that only light in the wave number range essential for laser detection reaches the detector. For the detector used in the preferred embodiment and the background conditions in the release gas, a bandpass of not more than 30 cm "1 should preferably be used to prevent the detector from overloading, while providing a Sufficient transmitted laser signal for a satisfactory dynamic range An amplifier 490 is provided to amplify the detection signal output by the detector 450. The data acquisition / display / output module 600 includes a data processing computer 610 such as for example a PC-based computer control system The data acquisition / display / output module 600 also includes a 100 KHz amplification amplifier 620, through which the signals from the detector module 400 are channeled into the harmonic detection operation mode (discussed later herein.) Computer 610 receives detector absorption spectra 385 of reference (after amplification by amplifier 386) and of detector 450 (after amplification by amplifier 490 and in harmonic detection mode, amplifier 620 of fixation to 100 KHz) and the computer averages the periodic samples of the signal of the detector 450 to maximize the signal to noise ratio of the system. A total response time resulting from 1 to 5 seconds per time-averaged measurement is obtained, depending on the furnace conditions and the desired signal-to-noise ratio (that is, the averaging of more samples over a longer period will improve the ratio of signal to noise). After processing, the data may be displayed as a screen output, output to a printer or used to generate process control signals that are issued to sound an alarm that a predetermined condition has been met (e.g., hazardous quantities). of water that have been detected that can cause an accumulation of hydrogen resulting in an explosion) or are emitted to control process parameters (for example, to vary the speed of oxygen flow in the lance). The operation of the preferred embodiment will now be discussed with respect to Figures 5-13. Two different operating modes are possible - the direct absorption mode and the harmonic detection mode. In the direct absorption mode, a transmitted infrared laser beam is analyzed directly to detect absorption characteristics due to the gas phase species (eg, CO, C02, H20) in the release gas and the results are interpreted in terms of temperature and gas concentrations to allow real-time control of the process. This mode of operation is particularly suitable for release gas streams that are small in diameter and / or possess relatively low dust loads, such that the average maximum transmitted laser power is at least 10% of the original laser power. In the harmonic detection mode, an incident laser beam is modulated (either in amplitude or in wavelength) at a high frequency in addition to being scanned through a range of wavelengths. The transmitted laser beam is detected and processed using a phase detector device (e.g., clamp amplifier 620 shown in Figure 4) to the first or second harmonic frequency of the high frequency modulation. The absorption characteristics due to the species of the gas phase (for example, CO, C02, H20) in the release gas are observed and the results are interpreted in terms of temperature and gas concentrations to allow control of the process in time real. This mode of operation is especially suitable for stripping gas streams that are large in diameter and / or possess relatively high dust loading, such that the average maximum transmitted laser power is less than 10% of the original laser power . The direct absorption mode will be discussed first, referring to Figures 5-8. Briefly, the structure in Figures 1 to 4 described previously, operates as follows. The tunable laser source 300 emits a laser beam that is swept through a predetermined range of wavelengths. The laser is preferably swept over a wave number range of at least 3 cm "1 for maximum accuracy in the determination of the release gas In the preferred mode of direct absorption mode, the laser is swept over the range of wave numbers from 2111 to 2115 cm "1. Other ranges of wavelengths can be used to optimize detector performance to characterize the release gas streams from other steelmaking processes. The laser output power must be at least 100 microwatts to ensure proper detection sensitivity; however, the laser must emit laser only in one mode. When using a lead-diode salt laser source, the laser operating temperature should be between 85 and 110 K to ensure proper wavelength control while minimizing the use of liquid nitrogen refrigerant.

The module 500 of electronic components regulates the temperature of the. laser and injection current. In the preferred embodiment, the electronic components module regulates the injection current in such a way that the TDL 310 is swept in its wavelength tuning range at a frequency of 1000 Hz. The laser beam passes through the gas of detachment of the BOF 100 where certain wavelengths are absorbed by transitions of molecular vibration-rotation of molecules of CO, C02 and H20 in the release gas. The sensor module 400 detects the transmitted laser beam and outputs data to the data processing computer 610. The computer 610 stores the previously calculated theoretical transition spectra and compares the characteristics of the detected data such as laser transmittance and absorbance ratio of CO and C02 (defined later herein) with the calculated transmission spectra to determine measurements of the average gas concentration, temperature and other characteristics as discussed later in the present. In particular, the absorption intensities of the individual molecular transitions for CO and C02 depend on their concentration and temperature in well-defined relationships. By adjusting the transmission spectra measured with the theoretical calculations, measurements of average gas concentrations and temperature can be made along the optical line of sight. The theoretical calculations are based on the following method: (1) Absorption wave numbers (vi) and lower energy levels (E ") for individual CO vibrational transitions (for isotopes 12C160, 13C160, 12C180, 12C170 and 13C180) they are calculated for lower vibrational quantum numbers (v ") of up to 10 (using the method of R. Farrenq, et al., J. Mol. Spec., 1991, 375). (2) These values are then used as input data for the calculation of the CO absorbance spectra in which the shape of the calculated CO absorption characteristics are referred to as "Voigt profiles" (using the method of JH Pierluissi, et al., J. Quant. Spectrosc. Radiat, Transfer, 1977, 555). The input values in addition to Vi and E "(above) are the concentration of CO, Cco, expressed in partial pressure in units of atmospheres, the length of the path through the absorption gas medium, L, the gas temperature , T, in Kelvins, the average collision width,? L, for the CO absorption characteristic at the calculated temperature (experimentally determined in the work of P.L.

Varghese and R.K. Hanson, J. Quant. Spectrosc. Radiat. Transfer, 1991, 339), and the intensity of line S, (extracted from the HITRAN database, HITRAN database 1992, Version 2.31, Ontar Corp., 9 Village Way, North Andover, MA). (3) The absorbance spectra of CO are calculated for temperatures of 1500 to 2100 K, at intervals of 50 K. The relevant quantity measured is the laser transmittance, T (v), which is expressed as the ratio of the intensity of the incident laser, I0, at the detected laser intensity, I, for a given wave number, v. The resulting transmittance spectrum is directly related to an absorbance spectrum a (v) by a (v) = -log (T (v)).

Figure 5 shows data for an example in which measurements of a laser beam emitted above the mouth of a BOF at pilot scale and compared to a calculated transmittance spectrum will be made. The continuous curve shows the transmittance of the laser beam that indicates the absorbance of CO measured via the previous relationship. The discontinuous curve indicates a theoretical calculation of the transmittance characteristics for the CO, using an optical path of 0.5 m, a temperature of 1435 K, a partial pressure of 0.12 atmospheres and a total pressure of 1 atmosphere. The characteristic marked with an asterisk in the experimental transmittance is a prominent CO absorption that is not reproduced in the CO calculation. (4) Using the series of calculated CO absorption spectra, the CO absorption lines that are most sensitive to temperature are indicated (for example, the characteristics at 2112.6 cm "1 (vi) and 3113.9 cm-1 ( vi) in figure 5) and absorbance ratios Rt as a function of temperature are calculated: RT = a (Vi) / a (v0) (5) Then a ninth-degree polynomial is adjusted to these various proportions of Rt (using known curve fitting techniques) to generate a mathematical function that expresses the absorption ratios for the two chosen CO absorption characteristics throughout the range of temperature (1500 to 2100K). Using this method, the temperature of the gas can be calculated in real time for the signals of the optical detector. The transmittance data as a function of the wave number (as shown in Figure 5) are generated every second or similar and the magnitude of the transmittance at specific wave numbers is extracted. The transmittance is rapidly converted to absorbance values by the 610 computer using the relationship indicated above. The absorbance ratio for the chosen absorption characteristics is then used as an input to the polynomial setting for Rt and the resulting value of the temperature is displayed by the computer and stored in memory. Note also that, since the absorbance is directly proportional to the CO contraction along the optical path lengths, the partial presence of CO can also be extracted from this calculation in real time. Figure 6 shows a graph of the temperature and transmittance of the laser as a function of a time through a heating. The temperature (upper curve) is calculated as described above. The laser transmittance shown in Figure 6 (bottom curve) is the value of the peak transmittance at a wave number of 2114.1 cm-1. The maximum transmittance of the laser through the flow of the gas of detachment is related to the dispersion caused by the greater number of particles entrained in the gas of detachment, also as the configuration of gases that absorb infrared along the line of sight optics. At 2114.1 cm "1 little molecular absorption of CO and C02 is expected and the reported transmittance of the laser represents mainly the estimation of the laser beam due to dispersion by dust particles, a substantial increase in the transmittance of the laser started at approximately 1300 seconds of blowing time with 02 as measured during pilot-scale experiments Several gaps in the data shown in Fig. 6 occur when a detector lance is lowered into the furnace for extraction of metal samples during blowing The detector lance, when lowered, effectively locks the infrared laser beam for approximately 20 seconds during each sample extraction.This situation does not occur in a standard commercial BOF. the present time, this method for real-time measurement of temperature and gas concentration can not be used for carbon dioxide (the small absorption characteristics of Figure 5 that are not adjusted in the calculated transmittance spectrum [dashed curve], the most prominent of which is marked by an asterisk). The main obstacle to implement this method for steel fabrication is the lack of fundamental data for the C02 absorption transitions as a function of temperature, at the high temperature of interest, to be used in the calculations described above.

However, much can be learned about the relative concentrations of CO and C02 by simply following a ratio of the absorption intensities for the absorption lines of the two gases throughout the oxygen blowing. The proportion used is: Rabs = AbSco / (AbSco - C * [AbSc02]) where Absc0 and Absco2 are the real-time absorbance values of the absorption characteristics of CO and C02 at 2112.6 and 2113.8 cm "1 respectively (see figure 5) and c is a constant whose value is selected in such a way that the ratio R The absorbance values of CO and C02 are approximately equal to the proportion of CO and C02 observed experimentally, Figure 7 shows a graph of the laser transmittance signal (lower curve, repeated from Figure 6) and the Rftbs function during a warm-up (that is, plotted as a function of the elapsed blow time). In this illustration, the constant "c" is chosen equal to 10, thus producing a value for R ^ s of approximately 0.8 (which is similar to the proportion of concentrations of C0 / C02 observed experimentally during most of the oxygen blowing, as shown in figure 7 (upper curve). The value of the proportion function begins to fall to approximately 1350 seconds on this graph and decreases rapidly to approximately 1500 seconds. The analysis of samples of metal samples extracted during the blow (again, causing the various gaps in the data shown in Fig. 6 and 7) show that the initial drop in Rñbs and the rise in the maximum transmittance of the laser are presented for a carbon content of 0.7%. Significant changes in these two measured optical properties continue to a melt carbon content of 0.03%. The computer can calculate and show R ^ s and the initial drop can be used to indicate that the carbon content has reached approximately 0.7%. During pilot-scale experiments, measured gas temperature values and the behavior of the maximum transmittance of the laser and R ^ s were sufficiently repeatable for approximately 10 warm-ups to demonstrate that this method can be used to extract real-time values of gas temperature , relative concentration of CO and C02 and carbon values in the endpoint melt for applications for which the maximum transmittance of the laser is greater than 0.1. The presence of hydrogen is detected by verifying transmission spectra corresponding to the water absorption line, for example, characteristics at a wave number of 2114.5 cm "1. Figure 8 shows a graph of water absorbance as a function of time. There can be seen clearly transients where the absorbance increases suddenly (that is, the transmittance in these spectra decreases) indicating high levels of water vapor During the normal steelmaking process in a pilot scale BOF, Water absorption lines were observed only briefly when the alkaline flux was added to the melt prematurely at the oxygen blowing frequency and during the extraction of metal samples for analysis by means of a sampling lance. water in the release gas during preheating periods (not shown in Figure 8). preheating the refractory lining of the furnace is carried out by blowing oxygen to combust coal and / or mineral coal and strong water line absorptions are continuously observed under these conditions. The absorption peaks at other times indicate an abnormally high level of water vapor and the 610 computer can check the signal level at 2114.5 cm "1 such that the detection of a water vapor level above a certain threshold It can be used to trigger an alarm or signal to an operator that potentially dangerous levels of hydrogen gas may be present.This is only an indirect indication of the presence of hydrogen, since it is H20 instead of hydrogen per se that is detected. However, because verification is performed on the actual release gas, this method of verification is more reliable than the conventional method of verifying the flow to and out of the water-cooled lance or exhaust pipe for water leaks. be a source of excess hydrogen The preferred embodiment of the harmonic detection operation mode will be described with respect to Figures 9-13. The aspects that differ from the direct absorption mode will be discussed in detail. In this mode, the TDL beam is modulated in terms of wavelength by rapidly varying the injection current with a 50 KHz sine wave form as the beam is swept in its wavelength tuning range. In the preferred mode in this way, the wavelength of the laser beam is swept over a range of wave numbers from approximately 2090 to 2093 cm "1. The second harmonic of the laser signal transmitted in the detector is then detected using the amplifier 620 of 100 KHz. It has been shown that this method allows the detection of TDL beams that have been attenuated by 5 orders of magnitude of their initial intensity.The precise frequencies of laser tuning and wavelength modulation are not critical (length modulation of high frequency wave up to several gigahertz is possible.) The ratio between the presence of laser sweep in its tunable range and the wavelength modulation frequency should preferably be at least 1: 1,000. continued to determine the characteristics of the release gas in the harmonic detection mode, the examples given are for a commercial basic oxygen furnace A scale and signals modulated by wavelength are demodulated at the second harmonic frequency using a fixation amplifier. The resulting waveforms resemble a second mathematical derivative of the transmission spectrum with absorption peaks going to negative. For convenience, these calculated second harmonic methods and signals are referred to as "2f" signals. The calculated signals 2f produced using an algorithm of programming elements (to be described later herein) that transform either the calculated direct or experimental absorption spectra to the corresponding second harmonic spectra ("2f"). The input spectra can be either normal transmittance spectra or non-standardized detector signals.

This algorithm can also be used to produce first harmonic spectra ("lf") or other higher harmonic spectra if desired. This procedure is necessary for the quantitative interpretation of the harmonic spectra in terms of the temperature and composition of the release gas, since the measured 2f spectra can not easily be "inverted" to simple transmission spectra that are easily interpreted. Previous research (notably, J. Reid and D. Labrie, App. Phys. B, 1981, 203) have shown that existing investment procedures are only successful for gaseous media that are almost very transparent and are not appropriate for the present application . The present process is similar to that followed in the direct absorption method described above. It allows to construct 2f spectra calculated for a series of temperatures and considerations of release gas. The spectral characteristics that are most sensitive to these variables for a given laser wavelength range are then selected and then a functional adjustment of eg the intensity ratio of two absorption lines 2f for CO is derived and used to adjust the detector data observed experimentally to produce real-time values of the temperature of the release gas. Information of the absorption line form, which includes the peak width and number position, wave, can also be used for this purpose. The algorithm of programming elements for the transformation of spectra of transmittance to spectra 2f simulates the action of a fixing amplifier in the electrical output of the detector module and carries out the following operations. An input transmittance spectrum (either calculated according to the direct absorption method described above or measured experimentally) is expanded by interpolating the additional data points using cubic flute adjustments. Since the sweep of the laser through its wave number tuning range is linear with respect to time, the resulting expanded transmittance spectrum is represented as transmission intensity with respect to time. In this representation, at least 10 data points are present for each cycle of the high frequency harmonic to be evaluated (100 KHz for the second harmonic, in the present example). Then the intensities of the expanded transmission spectrum are redistributed in time to represent the action of a sinusoidal modulation of the laser wave number by high frequency modulation as it is swept through its wave number tuning range. The minimum amplitude of the sinusoidal redistribution is equal to the experimental modulation amplitude, while the frequency of the sinusoidal redistribution is equal to the experimental value of 50 KHz. The mathematically expanded and "modulated" transmission spectrum is then multiplied by a sine wave at the frequencies of the experimental fixation amplifier, in this case, the second harmonic frequency at 100 KHz. Then the resulting function is filtered mathematically with a low pass function. The additional data points used to expand the original transmittance spectrum are removed to simplify the digital comparison with the experimental data and the result is a mathematical 2f spectrum that is essentially identical to the experimentally measured data. An example is shown in Figures 9a and 9b. Figure 9a shows a non-standardized, experimental direct absorption spectrum of carbon monoxide and water vapor obtained in the laboratory with the configuration of the release gas detector described above with reference to Figures 1 to 4. Figure 9b shows the measured 2f spectrum (continuous curves) and a calculated 2f spectrum (dashed lines) calculated using the algorithm described above of the direct absorption spectrum of Figure 9a. The measured and calculated spectra 2f of Figure 9 show excellent agreement. Figure 10a shows a calculated transmission spectrum for CO at 0.5 atmospheres partial pressure, 3.65 trajectory length and 1900K (2960 ° F). Figure 10b shows (as a dashed curve) a spectrum 2f calculated from the spectrum of Figure 10a. Figure 10b also shows (as a continuous curve) an experimental spectrum 2f measured in a full-scale BOF during oxygen blowing. A comparison of the two curves in Figure 10b shows good agreement of the position, shape and relative intensities of the various absorption characteristics in the 2f measured and calculated signals, even without including the contribution of C02 in the calculated 2f spectrum. The characteristic at 2091.55 cm "1 (referred to as" a ") is a line of CO absorption that is particularly sensitive to temperature, while the characteristic of CO at 2091.92 cm" 1 (called "b") is reasonably constant with the variable temperature. The ratio of these two intensities can be used to track the temperature of the release gas throughout the oxygen blow, as illustrated in Figure 11. Figure 11 shows a graph of the ratio of intensities of the characteristics a and b in the figure 10b. The ratio of intensities of these characteristics in the calculated 2f spectra of Figure 10b have also been calculated and these intensity ratios were found to be substantially linear with respect to the temperature in the range of 0.5 to 0.9 which corresponds to a temperature range of approximately 1750K to approximately 1900K. The proportions of experimental intensities plotted in Figure 11 can be converted to corresponding temperatures based on this linear relationship, for example, a value of 0.7 corresponds to a temperature of about 1825K. The relative concentrations of CO and C02 are determined using the characteristics called "a" and "c" in Figure 10b. Most of the strong absorption characteristics in Figure 10b are due to carbon monoxide. However, the bump-like characteristic called "c" in the experimental curve of Figure 10 at 2092.23 cm "1 is due to C02 in the release gas, the intensities of the characteristics of CO and C02 (referred to as" a "and "c" respectively) are denoted Ico and Ico2, respectively and are combined in the function: Proportion = Ico / (ICo + [* IC02J) where "k" is an arbitrary constant used to produce a similar proportion to the experimentally observed results, as in the equation for R ^ s above.

Figure 12 shows a graph of this intensity ratio, which is used to track the relative concentrations of CO and C02 throughout the oxygen blowing. The graph of figure 12 corresponds to the heating illustrated by the graph of figure 11, using a value of k = 0.1. As shown in Figure 12, the CO / C02 ratio is very stable in most of the blowing. As the melt approaches the final stages of decarburization, however, the CO at the loosening site is oxidized directly to C02. At this point, the value of the proportion function drops rapidly (as shown in Figure 12 beginning at approximately 1250 seconds of elapsed blow time). The values of the proportion functions for various CO and C02 absorption characteristics can be useful for determining the carbon content in the final melt in real time for applications where the continuous detector data can be obtained during the decarburization stage of the final cast. For some regions of TDL tuning in the range of 1700-2500 cm "1 (4.00 - 5.88 μm), this method for determining end-point carbon content does not work as well .This is mainly due to the very large increase in the C02 absorbance at the end of the oxygen blowing and a very large attenuation in the laser beam through the release gas In this case, a second procedure can be used to verify the carbon content of the end point. 2f "are recorded as a function of the wave number (as in Figure 10b, solid curve) every second or approximately and the average absolute value of the 2f spectra (hereinafter referred to as" signal strength 2f ") is calculated by the computer 610 for each spectrum This signal strength 2f is shown by the computer 610 and stored in the memory throughout an oxygen blow The behavior in time of the intensity of ñal 2f exhibits a characteristic and repeatable response with respect to blow time and accumulated oxygen. Figure 13 shows the intensity of the signal 2f (lower curve) as a function of the blowing time of 02 for a full-scale BOF heating (this is a different heating than that illustrated in Figures 11 and 12). For most heating, the intensity of the 2f signal advances to zero during the final stage of the decarburization of the melt. In addition, for some heating with very low final melt carbon concentrations, the signal intensity 2f becomes nonzero before the end of the oxygen blowing, due to a resulting decrease in the C02 concentration. In addition, the disappearance time and reappearance of the signal intensity 2f near the end of the oxygen blowing appears to be correlated with the wavelength of the laser, such that the longer wavelengths (lower wave numbers) give as a result shorter periods when the signal intensity 2f is zero. The characteristics of these signal intensity curves 2f can be useful for adjusting the release gas detector to the measurement of the carbon content in the specific melt for specific steelmaking processes and are under further investigation. The total emission that falls on the detector 450 through the narrow-band optical filters 480a and 480b does not show spectral characteristics through the laser tuning range of 3 cm "1. The emission intensity signal of the release gas is evaluated by a single sweep of the laser by taking multiple samples of the electrical output signal of the detector 450 and amplifier 490 before the signal is channeled through the amplifier 620. Then the multiple samples are averaged by the 610 computer in real time and the result is displayed and stored in memory throughout an oxygen blow-up.An example of such an exhibit or screen is shown in Figure 13 (top curve) .The rapid decrease in release of the release gas, which starts at approximately 1100 seconds of the elapsed blow time, can be correlated with the carbon content of the melt between 0.06 and 0.03% by weight. Thus, an estimated value that the carbon content is in this range can be made from the detector signal even when the most widely applicable technique using the intensity ratio can not be used. The combination of the 2f signal strength and the total emission methods can be used to produce more precisely correlated measurements of the carbon content in the final melt due to the independent nature of these two measurements. Additional information concerning the ejection of liquid slag (this is "slope") from the furnace can be extracted from the release gas emission signal shown in Figure 13. The sharp decrease in emission intensity (upper curve) between 400 and 600 seconds of elapsed blow time correlates well with the "slope" of the furnace. The decrease is caused by the expulsion of slag particles through the detector's field of view. Rapid changes in signal strength can be detected by the computer 610 used to alert the oven operator (or provide a signal to a process controller) that the incline of the furnace is eminent or is in progress. The position of the oxygen lance and / or the oxygen flow rate can then be adjusted (either manually or automatically) to prevent or stop the "slope". Although a specific embodiment of the invention has been described, the invention is not limited to this embodiment. For example, the wavelength ranges need not be identical to those used in the preferred modalities. Rather, any range that includes characteristic lines of interest can be used and those of ordinary experience will appreciate that the technique of the invention can be adapted to analyze characteristics different from the concentrations of CO, C02 and H20. It will also be appreciated that a different range may be required to give optimum results in adapting the invention to a different steelmaking process than that of BOF described in the preferred embodiment. In addition, the invention is not limited to a tunable diode laser and an InSb detector. Instead, any source of reaction that can be swept through the desired range of wavelengths at a sufficient power level for the choice can be used and any detector of a material suitable for detecting the transmitted beam can be used. In this regard, it should be understood that the precise arrangement of mirrors, lenses and other components in the laser source module and detector module are necessary. Other arrangements can be used that perform the same functions of guiding and focusing a laser beam and blocking and filtering undesirable components of the detector. Thus, those skilled in the art will appreciate that, while the present invention has been described with respect to the structure and operation of a preferred embodiment, the appended claims are not limited to the specific structure and operation discussed above. On the contrary, there are numerous variations of the described modality that can be effected by those of ordinary experience without deviating from the scope of the appended claims. It is noted that, with regard to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Claims (38)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: • An apparatus for collecting data concerning one or more species in the gas phase of a release gas that is emitted from a steelmaking furnace. , characterized in that it comprises: transmission means for transmitting a laser beam through the release gas produced by the steel manufacturing furnace, the transmission means have a range of wavelength tuning of the laser beam; control means for controlling the transmission means to repeatedly scan or sweep the laser beam through a range of continuous wavelengths preset in its tuning range, the range of preset continuous wavelengths includes at least two lines of absorption of one or more species in the gas phase and detection means to detect the laser beam transmitted through the release gas and to convert the detected laser beam to an electrical signal, by means of which the apparatus is operable to collect the data in a non-intrusive manner with respect to the flow of the release gas away from the furnace.
2. An apparatus according to claim 1, characterized in that the control means comprise means for carrying out the wavelength modulation of the laser beam while scanning or sweeping with the laser beam through the range of preset wavelengths and wherein the detector means comprises a phase responsive device for detecting a harmonic of the laser beam modulated in wavelength transmitted through the stripping beam.
3. 3. A method for collecting data concerning one or more gaseous phase species of a release gas that is emitted from a steelmaking furnace, characterized in that it comprises the steps of: transmitting a laser beam through the release gas produced by the steelmaking furnace using a laser having a wavelength tuning range of the laser beam; repeatedly sweep the laser beam through a range of continuous wavelengths preset in its tuning range, the range of preset continuous wavelengths includes at least two absorption lines for one or more species in the gas phase; detecting the laser beam transmitted through the release gas and converting the detected laser beam to an electrical signal, by which the data is collected in a non-intrusive manner with respect to the flow of the release gas away from and away from the oven. .
4. The method according to claim 3, characterized in that the step of repeatedly sweeping the laser beam comprises the step of carrying out the wavelength modulation of the laser beam while sweeping with the laser beam to through the preset range of wavelengths and wherein the detection step comprises the step of detecting a harmonic of the laser beam modulated in wavelength transmitted through the release gas.
5. The apparatus according to claim 1, characterized in that it further comprises processing means for processing the electrical signal to determine at least one characteristic of the release gas in the steelmaking furnace.
6. An apparatus according to claim 5, characterized in that the processing means comprise means for storing calculated theoretical characteristics of the stripping gas and means for comparing the electric signal with the calculated characteristics to determine at least one characteristic of the stripping gas. .
7. The apparatus according to claim 5, characterized in that the processing means comprise means for extracting information from one or more preselected wavelengths of the electrical signal and means for determining the at least one characteristic of the release gas in base to the information extracted.
8. 8. The apparatus in accordance with the claim 7, characterized in that the processing means comprise means for determining at least one proportion value, each proportion value represents the proportion of absorbance values for two wavelengths and for using the at least one proportion value with a polynomial determined from theoretical spectral calculations to determine a temperature value.
9. The apparatus according to claim 5, characterized in that the transmission means comprise means for carrying out the modulation of the wavelength of the transmitted laser beam while sweeping the laser beam through the range. of wavelengths and wherein the detection means comprises means for detecting a harmonic of the modulated laser beam.
10. The apparatus according to claim 9, characterized in that the processing means comprise means for extracting information of intensity concerning at least two preselected wavelengths from the electrical signal and means for determining the at least one characteristic of the stripping gas based on a proportion of the intensity information for one or more pairs of preselected wavelengths.
11. The apparatus according to claim 9, characterized in that the detection means comprises a detector and the processor means comprises means for determining the total emission intensity incident on the detector and means for determining at least one gas characteristic of the detector. detachment based on the determined emission intensity.
12. The apparatus according to claim 9, characterized in that the means for detecting a harmonic detect the second harmonic and wherein the processing means comprise means for ascertaining an average signal strength of the second detected harmonic and determining means for determining the at least one feature of the stripping gas using the average signal intensity investigated from the second harmonic.
13. The apparatus according to claim 12, characterized in that the processing means further comprise means for determining the total emission intensity incident on the detector and wherein the determining means use the second average harmonic signal intensity investigated and the Total emission intensity to determine the at least one characteristic of the release gas.
14. 14. The method according to the claim 13, characterized in that it further comprises the step of processing the electrical signal to determine the at least one characteristic of the release gas in the steelmaking furnace.
15. 15. The method of compliance with the claim 14, characterized in that the processing step comprises the step of comparing the stored calculated theoretical characteristics of the stripping gas with the electric signal to determine the at least one measured characteristic of the stripping gas.
16. The method according to claim 14, characterized in that the processing step comprises the step of extracting information from one or more preselected wavelengths from the electrical signal and determining the at least one characteristic of the release gas in based on the information extracted.
17. 17. The method according to claim 16, characterized in that the processing step further comprises the steps of determining at least one proportion value, each proportion value represents the proportion of absorbance values for two wavelengths and using the At least one proportion value with a polynomial determined from calculations of theoretical spectra to determine a temperature value.
18. The method according to claim 14, characterized in that the transmission stage comprises the step of carrying out the wavelength modulation of the transmitted laser beam while sweeping the laser beam through the range of wavelengths and the detection step comprises the step of detecting a harmonic of the modulated laser beam.
19. 19. The method according to the claim 18, characterized in that the processing step comprises the step of extracting intensity information from at least two preselected wavelengths from the electrical signal and determining the at least one characteristic of the release gas based on a proportion of information of intensity for one or more pairs of preselected wavelengths.
20. The method according to claim 18, characterized in that the processing step comprises the step of determining the total emission intensity incident on a detector and determining the at least one characteristic of the release gas based on the emission intensity determined.
21. The method according to claim 18, characterized in that the step of detecting a harmonic detects the second harmonic and wherein the processing step comprises the steps of investigating an average signal intensity of the second harmonic detected and determining the minus one characteristic of the stripping gas using the average second harmonic signal intensity investigated.
22. The method according to claim 21, characterized in that the processing step further comprises the step of determining the total emission intensity incident on a detector and wherein the determining step comprises the step of determining the at least one characteristic of the release gas using the intensity of the second average harmonic signal and the total emission intensity.
23. The apparatus according to claim 1, characterized in that the transmission means comprise a tunable diode laser arranged to transmit a laser beam through the release gas produced by the steelmaking furnace wherein the control means comprising a control circuit electrically connected to the laser of the tunable diode to provide an injection current to the tunable diode laser, the control circuit includes a circuit that causes the injection current provided to the tunable diode laser to vary in such a way that the tunable diode laser emits a laser beam that repeatedly sweeps through the preset wavelength range.
24. The apparatus according to claim 23, characterized in that it further comprises a computer or computer, the computer or computer includes means for receiving the electrical signal and means for processing the electrical signal to determine the at least one feature of the release gas .
25. 25. The apparatus according to claim 23, characterized in that the circuit which causes the injection current provided to the tunable diode laser to vary causes the injection current to vary in such a way as to modulate the laser beam in wavelength at so much that a sweep of the laser beam is effected through the range of wavelengths and wherein the detection means comprises a clamp amplifier for detecting a harmonic signal from the modulated laser beam.
26. 26. The apparatus according to claim 25, characterized in that it further comprises a computer or computer, the computer includes means for receiving the electrical signal and means for processing the electrical signal to determine at least one characteristic of the release gas.
27. 27. The apparatus according to claim 21, characterized in that the preset wavelength range is a range that is approximately 2 to 4 cm "1.
28. 28. The apparatus according to claim 27, characterized in that the continuous range Preset wavelengths are one of: (i) a range of wave numbers from approximately 2111 to 2115 cm-1 and (ii) a range of wave numbers from approximately 2090 to 2093 cm "1.
29. 29. The method according to claim 3, characterized in that the preset wavelength range is a range having a width of approximately 2 to 4 cm "1.
30. The method according to claim 29, characterized in that The preset wavelength range is one of: (i) a wave number range of approximately 2111 to 2115 cm "1 and (ii) a range of wave numbers of approximately 2090 to 2093 cm" 1.
31. 31. The method according to claim 3, characterized in that at least two absorption lines include lines of absorption of CO at wave numbers of 2112.6 cm "1 and 2113.0 cm" 1.
32. 32. The method of compliance with the claim 3, characterized in that the at least two absorption lines include a line of absorption of CO at a wave number of 2112.6 cm "1 and a line of absorption of C02 at a wave number of 2113.8 cm" 1.
33. 33. The method of compliance with the claim 3, characterized in that the at least two absorption lines include lines of absorption of CO at wave numbers of 2091.55 cm "1 and 2091.92 cm" 1.
34. 34. The method according to claim 3, characterized in that the at least two absorption lines include a line of absorption of CO at a wave number of 2091.55 cm "1 and a line of absorption of C02 at a wave number. of 2092. 33 cm "1.
35. 35. The apparatus according to claim 23, characterized in that the preset continuous range of wavelengths is a range having a width of approximately 2 to 4 cm "1.
36. 36. The apparatus according to claim 35, characterized in that The preset wavelength range is one of: (i) a range of wave numbers from approximately 2111 to 2115 cm "1 and (ii) a range of wave numbers from approximately 2090 to 2093 cm" 1.
37. 37. The apparatus according to claim 8, characterized in that the transmission means are located in such a way that the laser beam is transmitted through the release gas just above the mouth of the furnace
38. 38. The method according to claim 3, characterized in that the transmission step comprises transmitting the laser beam through the release gas just above the mouth of the furnace. METHOD AND APPARATUS FOR DETECTING THE COMPOSITION OF DETACHMENT GAS SUMMARY OF THE INVENTION A method and apparatus for the non-intrusive collection of release gas data in a steel fabrication furnace (100) including a structure and stages for transmitting is described. a laser beam (300) through the release gas produced by a steelmaking furnace, to control the transmission to repeatedly sweep the laser beam through a plurality of wavelengths in its tuning range and to detecting (400) the laser beam transmitted through the release gas and converting (600) the detected laser beam to an electrical signal. The electrical signal is processed to determine the characteristics of the release gas that are used to analyze and / or control the steelmaking process.