System for the removal of agglomerated build-up that interferes with off-gas analytical devices

Abstract

A gas analyzer system using extraction or in situ tunable diode lasers (TDLAS) or infrared or Fourier Transfer infrared (IR / FTIR) analysis methods that incorporates one or more analytical system devices including a gas sampling extraction probe or TDLAS shielding probes or IR / FTIR optical windows together with, an associated cleansing assembly that creates a shockwave by the sudden release of a preselected volume of cleansing gas at a pressure of between 3 BAR and 10BAR with a release flow rate of greater than 100 1 / s to effect to remove built-up dust and agglomerates from said analytical system devices and thereby keep said gas analyzer system operational.

Description

[0001] SYSTEM FOR THE REMOVAL OF AGGLOMERATED BUILD-UP THAT INTERFERES WITH OFF-GAS ANALYTICAL DEVICES

[0002] SCOPE OF THE INVENTION

[0003] The present invention relates to a system for the removal agglomerated build-up in gas extraction probes, shielding probes, on optical windows and the like wherein said agglomerated build-up interferes with the analysis of industrial off-gases from metallurgical furnaces and more preferably, steelmaking furnace by extractive methods, tunable diode lasers (TDLAS) and IR or Fourier Transform IR (FTIR) sensors.

[0004] BACKGROUND OF THE INVENTION

[0005] It is common industrial off-gas analysis practice to use probes to extract a sample of off-gas to be transported to a remote analyzer as described in United States Patent No. 10648901 B2 or to use a TDLAS system equipped with optical windows and two gas shielding probes as described in international patent application W02002 / 090943, the contents of which are incorporated herein by reference, or to use an optical window(s) to collect a spectrum of gases for IR and / or FTIR gas analysis as described in publication FTIR: A Flexible Tool for Industrial Gas Analysis | AIChE Nordstrom, et al American Institute of Chemical Engineers, June 2018. However, as documented in United States Patent No. 10,948,184 B2 which pertains to obstruction build-up commonly encountered in TDLAS system shielding probes and in reference Understanding Optical Windows | Edmund Optics, such build-up is a chronic problem when analyzing industrial furnaces gases with these methods.

[0006] To mitigate the build-up problem, such analytical methods commonly incorporate a gas purging method typically using an inert gas such as N2 whose flow is designed to act as a cleansing gas media to remove build-up in extraction probes, or, to remove build-up on the optical windows or in the shielding probes in TDLAS systems, or, on the optical windows used to collect spectrum in the IR or FTIR methods. In conventional gas purging operations, a flow of purging gas is provided at flow rates of typically but not necessarily between about 30 and 40 1 / minute, for extractive analysis in a reverse direction flow to extraction during periods when the probe is not extracting process gas for analysis, and, for TDLAS analysis as a continuous or semi-continuous flow across the face of the associated optical windows and subsequently through the shielding probes , and, for IR and FTIR analysis across the face of optical widows used to collect the spectrum. While such inert gas purging methods can be somewhat effective for removing loosely bound dust that collects in the probes and on the optical windows, the flow of purge gas is largely ineffective for removing harder or denser agglomerates that can build up inside or at the open end of the extraction or shielding probes or on the optical window. This is largely because the purge gas is compressible, and hence, when the flowing purge gas encounters a hard or dense build-up, the gas simply compresses and flows over and around the obstruction without removing it. Also because of electrostatic forces, it is common for a thin layer of dust particles to adhere to optical windows making it difficult to completely remove with the purge gas method.

[0007] The problem of build-up is particularly acute in many metallurgical processes and in particular steelmaking furnaces because of the presence of molten or semi-molten particles of slag and metal being carried along with other solid dust particles in the off-gas stream. When this mixture of particles contacts probes in the proximity of the probe open end or the optical windows, the mixture can readily stick together causing a hard agglomerated build up that can grow over time into a larger obstruction as more and more material continues to accumulate. This build-up problem is exacerbated if a molten slag or metal splash is ejected from the furnace proper and strikes the probe or the optical window as can happen from time to time in many metallurgical and steelmaking furnace applications. Overtime, such built-up agglomerates can plug the open end of extraction probes or block the laser beam line of sight through shielding probes with TDLAS systems or block or interfere with spectrum collection with IR and FTIR systems. In these situations, the inert gas purging method is largely ineffective for removing such agglomerated materials and the probes or optical windows will require manual maintenance and / or repair so that the off-gas analysis system can resume effective operation.

[0008] Extractive gas analyzers, TDLAS analyzers or IR spectrum analyzers are used for the analysis of exhaust off-gases produced by industrial furnaces, such as metallurgical and steelmaking furnaces is known. The applicant’s United States Patent No. 10648901 B2, the entirety of which is incorporated herein by reference, discloses an extractive off- gas analyzer system used to analyze H2O vapour, CO, O2, CO2, and H2content in steel furnace off-gas streams. In particular, analyzing the furnace off-gas components allows for the control of inputs and furnace operating parameters to optimize the performance of combustion processes in electric arc furnace (EAF) or basic oxygen furnace (BOF) steelmaking operations. The system described in United States Patent No. 10648901 B2 incorporates a longitudinally elongated sampling probe, such as is described in United States Patent No. 5777241 to EVENSON, the entirety of which is incorporated herein by reference. Typically, such probes are provided with a length of about 1 or 2 meters, and have a hollow interior opening at a distal end and a gas sampling port or inlet therein. The probe sampling port or inlet provided in fluid communication with a remote gas analyzer by way of a 0.75 -1 .5 cm diameter gas sampling line which fluidically connects with a vacuum pump. The probe distal end is adapted to be positioned through the side of the fume or flue duct of the industrial furnace and in the furnace off-gas stream. The vacuum pump operated to continuously extract and convey to the analyzer via the gas inlet, sampled process off-gas for analysis.

[0009] Similarly, international patent application W02002 / 090943 to Dietrich describes a laser method to analyze one or more gas species for control of industrial furnaces involving the use of two facing shielding probes each equipped with an optical window at their closed end to protect the laser emitter and receptor from contamination with the furnace gases. These shielding probes extend partway across the fume or flue duct to improve the reliability of TDLAS laser signal transmission and typically incorporate a continuous or semi-continuous flow of inert purge gas in the direction towards the distal open end to minimize build-up accumulation inside the probes and on the optical windows.

[0010] Similarly, as previously cited herein, 1R and FTIR methods can also be used to analyze off-gas for control of industrial furnaces. Such infrared methods use an optical window(s) to collect a spectrum of gases for 1R and / or FTIR gas analysis. As discussed in detail below, these optical windows are prone to build-up of dust and agglomerates that affect their optical transmission performance. Optical windows used in TDLAS and IR / FTIR systems are flat, optically transparent plates that are typically designed to maximize transmission in a specified wavelength range, while minimizing reflection and absorption. They are often used to protect optical systems and electronic sensors from a harsh outside environment. Because windows introduce no optical power into a system, windows should be selected based on the material transmission properties, optical surface specifications, and the mechanical properties that match the application (reference Understanding Optical Windows | Edmund Optics). Dirt, agglomerates and dust collecting on the optical window can cause scatter, which is the deflection of light in multiple directions, resulting in reduced clarity and increased noise in the transmitted signals. This scatter can also absorb light, further reducing optical signal quality. Hence, keeping the optical windows clean is an important requirement for signal transmission (reference Why and How to Clean Your Optics — Firebird Optics). Conventional practice is to use inert gas purging systems that flow gas across the face of the windows as a means to minimize said signal interfering build-up.

[0011] With conventional gas purging methods, replacement, maintenance and repairs to analytical system devices (herein collectively the extractive probe, shielding probes and optical windows are referred to as the “analytical system devices”) caused by agglomerate build-up and damage must take place at the exhaust fume extraction point where the devices are located usually near the top of the metallurgical or steelmaking furnace. This area is often located at a height of 10 meters or more above the shop floor, and as such, is often difficult to access and poses safety risks to maintenance personnel. Furthermore, conditions are hot and dusty which makes work difficult. For these reasons, maintenance personnel are prohibited from entering and working in this area when the furnace is operational. This means that the “analytical system devices” may remain inoperable and the plant may have to function without off-gas analysis based process control for extended periods of time lasting a week or longer before corrective action can be taken. Another major advantage of the current invention is that it is capable of removing large, agglomerated build-up that otherwise would require maintenance, repair or replacement of the “analytical system device” and thereby enables off-gas analysis process control systems to function more reliably without extended periods of interruption requiring expensive repair work. The applicant has recognized that with metallurgical and steelmaking furnaces, and particularly EAF or BOF furnaces, a mixture of molten slag and metal droplets along with solid dust particles may accumulate and build-up on the interior sidewalls particularly near the open end of extraction and shielding probes or on optical windows used in TDLAS and IR / FTIR systems. As this material mixture cools and solidifies it can adhere to said probes and optical windows and in such situations, conventional purging gas flows are frequently insufficient to dislodge agglomerated material. Over time these particles may thus occlude the extractive sampling probe or block the line of sight of TDLAS shield probes or disrupt the transmission of light through optical windows used in TDLAS and IR systems. In such an event, replacement or repairs of such devices is required which is both time consuming and expensive, requiring technicians to access and at least partially disassemble the “analytical system device” assemblies directly in the area of the exhaust fume duct.

[0012] SUMMARY OF THE INVENTION

[0013] Accordingly, one non-limiting object of the present invention is to provide a system that generates a high pressure shockwave that travels through the extractive probe, the shielding probes or across the face of the optical windows. For clarity, as used herein shockwaves include pressure waves which may travel at less than or which may exceed the speed of sound, and are similar to other wave forms in that it carries energy and can propagate. Such shockwaves are distinguished by an abrupt change in pressure or density of the medium, thereby creating a process of disruptive interference. Unlike traditional inert gas purge methods that are largely ineffective because the gas compresses and flows past the agglomerate without removing it, in the current invention, the shockwave is disruptive and assists in breaking apart and removal of built-up agglomerates as loosely held particulate matter so that said built-up agglomerates no longer impede or interfere with the effectiveness of “analytical system devices” used for analyzing industrial furnace off-gas flows such as those produced in metallurgical furnaces and most preferably in BOF and EAF steelmaking furnaces.

[0014] In another non-limiting embodiment, the invention provides for a shockwave dispersing system for extractive gas analyzers. The system is adapted to be periodically operated to effect probe cleaning by dislodging dust and agglomerated material from within the extraction sampling probe. It should be noted that the same shockwave system is also effective for remove dust and other loosely held material from within the probe and the associated gas supply lines during furnace operations and preferably without requiring significant interruption or cessation of gas analyzer operation as would normally be required when using conventional gas purging.

[0015] In another embodiment, the invention provides for removal of dust and / or agglomerate built-up material from analytical system devices that are used with an extractive gas analyzer system or a TDLAS laser gas analyzer or an infrared spectrometer gas analyzer.

[0016] In another non-limiting embodiment, a shockwave cleaning system operates by the sudden release of a volume of high pressure air or inert gas such as N2 cleansing gas directly into the “analytical system device” or within the off-gas system in close proximity of preferably 10 meters or less from the “analytical system device”. The system is operable to create a shockwave of sufficient intensity by the sudden release of a suitable volume of cleansing gas maintained at a pressure of at least about 3BAR and preferably between 5 to 10BAR and most preferably between 7 and 10BAR in less than about 0.3 seconds and preferably in less than about 0.2 seconds and most preferably in less than about 0. 1 seconds thereby releasing between about 20 to 280 liters (STP) of cleansing gas by the sudden release of said cleansing gas from a pressurized reservoir tank preferably sized between about 5 to 30 1 into the system analytical device with sufficient intensity to create the shockwave.

[0017] Typically, the stored pressurized volume of cleansing gas will be between about 5 and 30 1, however different stored volumes may be used.

[0018] In another non-limiting embodiment, the shockwave is generated by using a quick release valve such as a diaphragm value or the like to cause the sudden release of the pressured cleansing gas from the tank in approximately 0.09 to 0. 15 seconds.

[0019] In another non-limiting embodiment, for the volumetric preferred tank range of between 5 to 30 liters maintained at a pressure ranging between 3 and 10BAR, a shockwave of varying intensity is created when the release gas flow velocity is above about 75 1 / s and preferably ranges between about 150 to 3,000 1 / s. In another embodiment, the invention provides for a gas analyzer cleansing system, and preferably an extractive gas analyzer system, which is operable to effect the pressure induced pressure wave, and preferably shockwave cleansing of extractive gas analyzer probe and / or sampling lines by the supply of preselected volumes of pressures line cleansing gas, and preferably air or an inert gas such as nitrogen (N2) as a high pressure reverse shockwave induced gas flow. Most preferably, the cleansing system is provided as a part of system for industrial furnace gas analysis and control.

[0020] In another embodiment the invention provides an apparatus and method that are adapted to clean away built-up material in extraction and shielding probes and material adhering to optical windows without using larger volumes of lower pressure inert gas flowing for longer periods time. The pressure wave or shockwave generating apparatus is preferably more effective to remove dense agglomerates that would otherwise not be removed by the conventional purging method because of purge gas compression as it passes over and around agglomerated material. In preferred aspects, the present invention relies on a preselected relatively small release volume of air or inert gas of between about 20 to 280 liters (STP) of gas that has been suddenly released from a tank with a stored volume of between about 5 and 30 1 that was maintained at a pressure of at least about 3BAR and preferably between 5 to 10BAR and most preferably between 7 and 10BAR with the release time being less than about 0.3 seconds and preferably in less than about 0.2 seconds and most preferably in less than about 0. 1 seconds in a fashion that creates a wave front that is capable of dislodging and breaking-up accumulated dust as well as agglomerated material adhering to the “analytical system device”.

[0021] In another non-limiting embodiment, a shockwave generating gas cleansing system can be used to remove accumulated dust and agglomerates within the interior of the extraction probe or shielding probes or from the face of optical windows by using either a “short connection configuration” or a “remote connection configuration” as described herein.

[0022] In another non-limiting embodiment, the shockwave generating system can be designed to release gas of a specified volume and pressure at high speed from a suitably sized tank that has a short connection distance with an extraction probe, or a shielding probe or an optical window “analytical system device”. In such “short connection configuration”, the shock wave is created by the sudden release of a relatively small release volume of cleansing gas ranging between 20 to 135 liters (STP) from a suitably sized tank that has been maintained at a stored pressure preferably between 3 to 10 BAR and more preferably between 6 to 10 BAR and most preferably between 7 to 10 BAR with a release time of less than about 0.2 seconds and most preferably between about 0.09 to 0.15 seconds into a short tube with an inner diameter of preferably between 0.9 to 1 .6 cm and a length of less than 1 meter and preferably less than 0.5 meters and most preferably less than 0.3 meters with said short tube being connected directly to the “analytical system device” being cleaned.

[0023] In another non-limiting embodiment, the shockwave generating tank with the short connection configuration is between about 5 to 30 liters in size and preferably between about 5 to 15 liters in size and more preferably between about 5 to 10 liters in size.

[0024] In another non-limiting embodiment, the shockwave generating system can be located more remotely from said “analytical system devices”. In such “remote connection configuration”, the shockwave generating device is designed to suddenly release gas of a specified volume and pressure at high release velocity into a longer transport line up to 10 meters in length that connects to the ‘analytical system device”, In such configuration, the shockwave is created by release and / or expansion of stored volume of cleansing gas from a suitably sized tank of between about 15 to 30 liters maintained at a pressure preferably between 5 to 10 BAR and more preferably between 6 to 10 BAR and most preferably between 7 and 10 BAR with a release time of the cleansing gas of the order of 0.09 to 0. 15 seconds into a transport line of about 10 meters or less in length with an inner diameter of preferably between 3 to 5 cm and more preferably between 3.2 to 4.4 cm and most preferably between 3.6 to 4 cm with said transport line being connected fluidically to the “analytical system device” being cleaned.

[0025] In another non-limiting embodiment, the selection between a short connection configuration and a remote connection configuration is determined by the nature of the agglomerated material being removed with larger and harder agglomerates requiring a stronger shockwave generated by the sudden release of larger gas volumes, any physical constraints that may limit the size and locational positioning of the shockwave generating apparatus and any environmental constraints such as the presence of high heat and / or flames or other environmental factors which may limit apparatus serviceability. All things being equal, a short connection configuration is preferable over a remote connection configuration system since the tank size and cleansing gas volumes needed to generate a shockwave of sufficient intensity are typically reduced.

[0026] In another non-limiting embodiment, one or more shockwave generating apparatus may be employed to clean multiple analytical system devices.

[0027] In another non-limiting embodiment, remote connection configuration and short connection configuration shockwave generating apparatus’ may be combined to better clean an analytical system device.

[0028] In another non-limiting embodiment pertaining more specifically to extractive analyzer systems wherein a sample of furnace process gas is extracted through a sampling probe with its distal open end embedded in the off-gas in the fume system exiting the furnace and with said furnace process gas being subsequently transported from the probe to analyzer by a gas supply line typically with an internal diameter of about 0.5 and 1.5 cm, In such extractive system arrangements, a shockwave generating gas cleansing system can be configured to remove accumulated dust within both the gas supply line connecting the probe to the analyzer as well as agglomerates within the interior of the sampling probe by employing the “remote connection configuration” described herein. In such arrangement, a single suitably designed remote configuration shockwave system is connected to the gas supply line where the connection point is preferably less than 10 meters from the distal open end of the sampling probe. The shockwave generating system consisting of a tank of at least 5 1, preferably at least 15 liters and more preferably 30 liters for storing a corresponding volume of cleansing gas consisting of an inert gas or air maintained at a pressure between about 5 to 10BAR and preferably between 7 and 10BAR and a quick release valve to suddenly release said high pressure cleansing gas in less than about 0.2 seconds and preferably between about 0.09 to 0.15 seconds creating a reverse flow shockwave front passing through the gas supply line and the fluidically connected gas sampling probe thereby discharging a relatively small volume of cleansing gas and dislodged agglomerates into the off-gas flue through the open distal end of the sampling probe. To prevent dust or debris from entering the gas analyzer, such extractive analyzer systems often utilize a gas filter usually within the probe proper. In another un-limiting embodiment, with the remote shockwave device described herein, said filter can be repositioned to a location further downstream of the shockwave apparatus connection point to the gas supply line closer to the analyzer. In such configuration, a conventional gas purging arrangement would be used to remove loosely bound dust in the gas supply line from the analyzer and relocated filter and the remote connection configuration shockwave system described herein would be used to remove dust in the sampling line between said connection point and the probe as well as dust and larger agglomerated material build-up within the probe. The applicant has appreciated that providing the filter assembly at a more remote location, and spaced near the analyzer facilitates better and safer access for filter replacement, system maintenance and repair. Furthermore, because the filter is no longer in the probe inside of the flue duct it no longer needs to be of an expensive high temperature resistant stainless steel mesh design, and can be replaced with a more conventional fabric, paper or sock-type filter design.

[0029] In another non-limiting embodiment, in the event the extractive sampling system incorporates an outer larger diameter protective probe surrounding a smaller diameter central gas sampling tube in fluidic communication with the gas supply line and extending downwards with its the distal open end being in close proximity to the open end of the outer protective probe, a combined remote connection and short connection shockwave configuration can be used to clean dust from the gas supply line and agglomerated material within the sampling tube and within the outer protective probe. In said extractive system arrangement, a suitably designed remote connection configuration shockwave system is connected to the gas supply line where the connection point is preferably less than 10 meters from the distal open end of the gas sampling tube. The shockwave generating system consisting of a tank of at least 15 liters and preferably 30 liters containing the cleansing gas consisting of an inert gas or air maintained at a pressure between about 5 to 10BAR and preferably between 7 and 10BAR and a quick release valve to suddenly release said high pressure cleansing gas in less than about 0.2 seconds and preferably between about 0.09 to 0.15 seconds to generate a reverse flow shockwave front through the gas supply line and fluidically connected gas sampling tube discharging the small volume of cleansing gas and the dislodged agglomerates and dust into the off- gas flue through the open distal end of the gas sampling tube located near the open distal end of the outer protective probe. A second shockwave generating system using the most appropriate of a short connection configuration or a remote connection configuration as described herein is used to cleanout agglomerate build-up within the outer protective probe. If such extractive system arrangement contains a filter in the sampling tube or in the sample supply line, said filter can be relocated into the gas supply line downstream of the remote connection shockwave generating apparatus connection point as described elsewhere herein.

[0030] In another non-limiting embodiment, the use of the shockwave generating system to clean the gas supply line and the probe and gas sampling tube allows for the relocation of the expensive stainless steel mesh filter normally positioned at the open distal end of the gas sampling tube to a more accessible location in the gas supply line nearer to the analyzer. Applicant recognizes such filter relocation represents a significant cost saving since the expensive temperature resistant stainless steel mesh filter requires regular replacement usually on a weekly or biweekly basis and can now be replaced by a more conventional less expensive fabric sock filter, or paper filter. Additionally, relocation of the filter to a more accessible downstream location brings operational and safety benefits since it minimizes the need for system maintenance and repair personnel to have to go to the exhaust fume extraction point near the top of the metallurgical or steelmaking furnace on regular basis to inspect and change the stainless steel mesh filter.

[0031] In another non-limiting embodiment as it pertains to an extractive sampling system, because of the smaller volume of cleansing gas and rapid release rate, the shockwave generating inert gas or air used in the current invention can be introduced to clean the gas supply line and sampling tube and probe during periods when the off-gas is being extracted and analyzed with minimal effect on the analysis precision. For example, in a typical extraction analysis, the shockwave generating gas would affect the precision of the off-gas analysis for a period of only between 6 to 10 seconds. As such, the current invention allows cleaning of analytical system devices on demand on an as required basis which represents a significant improvement over conventional gas purge methods which can only be deployed when the off-gas is not being extracted for analysis. In another non-limiting embodiment, it is understood that the shockwave cleansing system can be designed as a single remote connection system as described herein to clean the gas sampling line and the probe assembly or as separate shockwave cleaning systems to separately clean the outer protective probe assembly and the inner sampling tube and the gas supply line.

[0032] The analytical system device cleansing apparatus is configured to introduce a preselected volume of pressurized cleansing gas into and along the interior of the extractive probe and / or the outer protective and or the inner gas sampling tube and / or the gas supply line and / or the TDLAS shield probes and / or across the face of optical windows with said cleansing gas being released from a pressurized tank of between about 5 liters to 30 liters in size containing a corresponding stored volume cleansing inert gas or air maintained at a pressure of between about 3 BAR and 10BAR, and preferably between about 7BAR to 10BAR and released over a time period of less than 1 second, preferably less than about 0.5 seconds, and more preferably between about 0.09 to 0.15 seconds. However, it is recognized that this invention allows for different combinations of volumes and / or pressures and / or release times provided such combinations create a shockwave or a pressure wave with sufficient intensity to breakup and dislodge solid aggregations that are interfering with the performance of said analytical system devices noted above.

[0033] Said shock wave cleansing apparatus is operable to effect the sudden release of the preselected volume of pressurized cleansing gas at a release flow rate of more than about 100 1 / s and preferably between 200 to 3,000 1 / s.

[0034] Although not essential, the system may also include a controller which is selectively operable to control the activation of the shockwave generating assembly. In non-limiting embodiments, the controller may be operable either automatically or manually to control initiation of the shockwave by actuating one or more valve assemblies either in unison or in sequence as most appropriate for effective cleaning. The table below summarizes some of the operational ranges specified in the current invention.

[0035] Accordingly, the present invention may reside in one or more non-limiting aspects, and which may include:

[0036] (i) An extractive gas analyzer cleansing system and preferably a pressurized gas cleaning system comprising, a longitudinally elongated gas sampling probe for extracting a gas sample, a gas supply line configured for supplying extracted sampled gas to a gas analyzer, and line cleansing assembly, the probe extending from a proximal end portion to an open distal end configured for positioning in an industrial furnace off-gas stream, and preferably a basic oxygen furnace BOF or electric arc furnace EAF furnace off-gas stream, and comprising, a tubular outer sidewall extending from said proximal end portion to said distal end, and defining a hollow interior, and a gas sampling tube extending longitudinal along said hollow interior, said sampling tube having an open inlet end spaced towards the distal end and an outlet end fluidically coupled to the gas supply line, the line cleansing assembly including a line cleansing gas source configured to create a shockwave by high speed release of a preselected volume of line cleansing gas stored at a pressure selected between about 3 BAR. and 10BAR, and preferably about 7BAR and 10BAR, the line cleansing gas source being in selective fluidic communication with the gas supply line via an inlet port intermediate said tube outlet end and said gas analyzer, and a line valve selectively actuable to effect flow of the shockwave cleansing gas into the gas supply line and into the fluidically connected gas sampling tube inlet end as a reverse line cleansing gas flow.

[0037] (ii) An extractive gas analyzer system for analyzing a furnace off-gas flowing in a furnace flue duct, and preferably an EAF or BOF furnace duct, the analyzer system comprising, a gas sampling probe, the probe being elongated along a longitudinal axis and extending from an open distal end disposed in the furnace flue duct to a proximal end spaced outwardly therefrom, the probe comprising, an outer sidewall extending about said axis from the open distal end towards the proximal end and defining a hollow probe interior, and an elongated sampling tube disposed at least in part in said probe interior and extending generally along said axis from an inlet end open to said interior and disposed towards said open distal end, to an outlet end disposed towards the proximal end, a gas supply line fluidically communicating the outlet end with a gas analyzer assembly spaced a distance from the furnace flue duct, the gas analyzer assembly being operable to draw said furnace off-gas from the flue duct into said sampling tube and along said supply line in a first flow direction for analysis; a line cleansing assembly selectively operable to suddenly release a preselected volume of pressurized line cleansing gas in a fashion that creates a shockwave in said gas supply line as a line cleansing method travelling in a direction opposite to said first flow direction, and wherein the preselected stored volume of pressured line cleansing gas is maintained in a tank of between 2 and 40 liters, preferably 5 and 35 liters, most preferably about 5 and 30 liters, and has a pressure selected at between about 3BAR and 10BAR, preferably between about 7 to 10BAR; and / or a probe cleansing assembly selectively operable to introduce a shockwave created by a sudden release of the preselected volume of pressurized probe cleansing gas into said probe interior as a probe cleansing shockwave method travelling in a direction outwardly from the open distal end, wherein the preselected volume of probe cleansing gas is maintained in a suitably sized tank between about 5 liters and 40 liters at a pressure selected between about 3BAR and 10BAR, preferably between about 7 and 10BAR; and a controller for controlling the line cleansing assembly and / or probe cleansing assembly to initiate a shockwave front by triggering the sudden release of said high pressure gas into the line and / or probe to remove built up material.

[0038] (iii) An extractive gas analyzer system for analyzing a furnace off-gas flowing in a furnace flue duct, and preferably an EAF or BOF steelmaking furnace flue duct, the analyzer system comprising, a gas sampling probe, the probe being elongated along a longitudinal axis and extending from an open distal end disposed in the furnace flue duct to a proximal end spaced outwardly therefrom, the probe comprising, an outer sidewall extending about said axis from the open distal end towards the proximal end and defining a hollow probe interior, and an elongated sampling tube disposed at least in part in said probe interior and extending generally along said axis from an inlet end open to said interior and disposed towards said open distal end, to an outlet end disposed towards the proximal end, a gas supply line fluidically communicating the outlet end with a gas analyzer assembly spaced a distance from the furnace flue duct, the gas analyzer assembly being operable to draw said furnace off-gas from the flue duct into said sampling tube and along said supply line in a first flow direction for analysis, a line cleansing assembly selectively operable to introduce a shockwave by the sudden release of a preselected stored volume of pressurized line cleansing gas into said gas supply line in a direction opposite said first flow direction, and wherein the preselected volume of pressured line cleansing gas is maintained in a tank selected at between about 2 liters and 40 liters, preferably about 5 liters and 30 liters, and has a pressure selected at between about 3BAR and 10BAR, preferably about 7 to 10BAR, a line valve selectively actuable to effect flow of the preselected volume of line cleansing gas into said gas supply line via an inlet port intermediate said outlet end and said gas analyzer, the inlet port being spaced 0.5 meters to about 10 meters and preferably about 5 meters to about 8 meters from said probe.

[0039] (iv) A gas analyzer system comprising, a gas analyzer for analyzing one or more constituents in an industrial furnace off-gas stream, the gas analyzer including an analyzer component selected from the group consisting of a gas extraction port, an optical emitter and an optical receptor, a longitudinally elongated mounting or shielding tube, and a high velocity gas blow system for effecting shockwave cleansing of said tube and / or analyzer component, the tube extending from a proximal end portion to an open distal end and comprising a tubular outer sidewall configured for positioning in the industrial furnace off-gas stream extending from said proximal end portion to said distal end and defining a hollow interior, and said analyzer component being substantially housed within the hollow interior, and preferably being spaced towards the distal end, the high velocity gas blow system including a high pressure gas source configured to create a gas burst shockwave from the sudden release of a preselected volume of analyzer cleansing gas at pressure selected at between about 3BAR and 10BAR, and preferably about 7 to 8BAR, the high pressure gas source being in selective fluidic communication with the tube interior via an inlet port spaced towards, and preferably adjacent said proximal end portion, and a valve assembly selectively actuable to effect flow of the volume of analyzer cleansing gas from said inlet port and into said hollow interior as a reverse gas burst flow.

[0040] (v) A TDLAS gas analyzer system comprising a laser emitter with an adjoining optical window located in a housing outside of the fume duct which is attached to an adjoining longitudinally elongated TDLAS shielding probe, and, a counter facing TDLAS shielding probe adjoining to a housing attached to the opposite side of the fume duct maintaining an optical window and a laser receptor wherein each shielding probe is extending from a proximal end portion at the outer sidewall of the fume duct to an open distal end towards the center of the fume duct creating an open space between the two counter facing shielding probes with said open space being positioned within the industrial furnace off- gas stream. With this arrangement the laser beam is designed to transmit from the emitter through its adjoining optical window and shielding probe into the open space containing the industrial furnace gas to effect gas analysis and then subsequently to enter into and pass through the second shielding probe and adjoining optical window for collection by the receptor. As documented in the previously cited in United States Patent No. 10,948,184 B2, such horizontal shielding probe configurations are prone to the accumulation of agglomerated material build up that cannot be dislodged by conventional gas purging methods and will eventually block the line of sight between the laser emitter and receptor and thereby prevent analysis of the industrial gas. Such problems can only be resolved by maintenance personal going to this difficult to access and unsafe location near the top of the furnace to remove blockage for the shielding probes and clean the optical windows. The current invention optionally may address this problem by using two shockwave creating apparatus, one for each set of shielding probe and optical window and with said shock wave apparatus being either a short connection configuration or a remote connection configuration as is most appropriately suited for the plant conditions. Said apparatus are designed to create a shockwave front that will dislodge and remove the agglomerated material by the sudden release of a relatively small volume of high pressure cleansing gas maintained in a tank sized between about 5 liters to 30 liters at a preselected cleansing gas pressure of between about 3 to 10BAR, and preferably about 7 to 10BAR, and a quick release valve that releases the cleansing gas over a time of less than about 1 second, preferably over 0.5 seconds or less and more preferably over about 0.07 to 0.20 seconds with said high pressure gas source being in selective fluidic communication with the shielding probe interior via an inlet port spaced towards, and preferably tangential to the face of the optical window near said proximal end portion of each shielding probe, and the valve assembly selectively actuable to effect a sudden release of the pressurize cleansing gas to remove loosely deposited material and difficult to dislodge agglomerates off the face of each optical window and out of the interior of each shielding probe.

[0041] (vi) A gas analyzer system for analyzing one or more constituents in an industrial furnace off-gas stream with said gas analyzer including an analyzer components consisting of an optical window to collect a spectrum of gases for IR and / or FTIR gas analysis and a “remote connection” or a “short connection” shockwave generating apparatus consisting of a suitably sized pressurized tank of cleansing gas maintained at a pressure between about 3 to 10B AR with a quick release valve system connected to an inlet port positioned tangentially to the optical window so as the shockwave front will cross the face of the window and thereby remove dust and agglomerates that are interfering with the transmission of IR spectrum through the window and which would otherwise require maintenance personal going to this difficult to access and unsafe location near the top of the furnace to clean the optical windows.

[0042] (vii) A gas analyzer cleansing system comprising, a longitudinally elongated gas sampling probe for extracting a gas sample, a gas supply line configured for supplying extracted sampled gas to a gas analyzer, and line cleansing assembly, the probe extending from a proximal end portion to an open distal end configured for positioning in an industrial furnace off-gas stream and comprising, a tubular outer sidewall extending from said proximal end portion to said distal end and defining a hollow interior, and gas sampling tube extending longitudinal along said hollow interior, said sampling tube having an open inlet end spaced towards the distal end and an outlet end fluidically coupled to the gas supply line, the line cleansing assembly including a line cleansing gas source configured to supply a preselected volume of line cleansing gas at pressure selected at between about 3BAR and 10BAR, and preferably about 7 to 10 BAR, the line cleansing gas source being in selective fluidic communication with the gas supply line via an inlet port intermediate said tube outlet end and said gas analyzer, and a line valve selectively actuable to effect flow of the volume of line cleansing gas into the gas supply line and from said gas sampling tube inlet end as a reverse gas burst line cleansing gas flow.

[0043] (viii) An extractive gas analyzer system for analyzing a furnace off-gas flowing in a furnace flue duct, the analyzer system comprising, a gas sampling probe, the probe being elongated along a longitudinal axis and extending from an open distal end disposed in the furnace flue duct to a proximal end spaced outwardly therefrom, the probe comprising, an outer sidewall extending about said axis from the open distal end towards the proximal end and defining a hollow probe interior, and an elongated sampling tube disposed at least in part in said probe interior and extending generally along said axis from an inlet end open to said interior and disposed towards said open distal end, to an outlet end disposed towards the proximal end, a gas supply line fluidically communicating the outlet end with a gas analyzer assembly spaced a distance from the furnace flue duct, the gas analyzer assembly being operable to draw said furnace off-gas from the flue duct into said sampling tube and along said supply line in a first flow direction for analysis, a line cleansing assembly selectively operable to introduce a preselected volume of pressurized line cleansing gas into said gas supply line as a line cleansing gas flow in a direction opposite said first flow direction, and wherein the preselected volume of pressurized line cleansing gas is stored at a volume selected at between about 11 and 401, preferably about 251 and 301, and has a pressure selected at between about 3BAR and 10BAR, preferably about 7 to 8BAR, a probe cleansing assembly selectively operable to introduce a preselected volume of pressurized probe cleansing gas into said probe interior as a probe shockwave induced cleansing gas flow in a direction outwardly from the open distal end, wherein the preselected volume of pressurized probe cleansing gas is stored at a volume selected at between about 51 and 501, preferably about 51 and 101, and has a pressure selected at between about 3BAR and 10BAR, preferably about 7 to 10BAR, and a controller for controlling the line cleansing assembly and probe cleansing assembly to selectively effect the line cleansing gas flow and / or probe cleansing gas flow.

[0044] (ix) An extractive gas analyzer system for analyzing a furnace off-gas flowing in a furnace flue duct, the analyzer system comprising, a gas sampling probe, the probe being elongated along a longitudinal axis and extending from an open distal end disposed in the furnace flue duct to a proximal end spaced outwardly therefrom, the probe comprising, an outer sidewall extending about said axis from the open distal end towards the proximal end and defining a hollow probe interior, and an elongated sampling tube disposed at least in part in said probe interior and extending generally along said axis from an inlet end open to said interior and disposed towards said open distal end, to an outlet end disposed towards the proximal end, a gas supply line fluidically communicating the outlet end with a gas analyzer assembly spaced a distance from the furnace flue duct, the gas analyzer assembly being operable to draw said furnace off-gas from the flue duct into said sampling tube and along said supply line in a first flow direction for analysis, a line cleansing assembly selectively operable to introduce a preselected stored volume of pressurized line cleansing gas into said gas supply line as a high velocity gas burst in a direction opposite said first flow direction, and wherein the preselected stored volume of pressured line cleansing gas is selected at between about 21 and 401, preferably about 21 and 301, and has a pressure selected at between about 3 BAR and 10BAR, preferably about 7 to 8BAR, a line valve selectively actuable to effect flow of the preselected stored volume of line cleansing gas into said gas supply line via an inlet port intermediate said outlet end and said gas analyzer, the inlet port being spaced 0.5 meters to about 8 meters and preferably about 5 meters to about 7 meters from said probe.

[0045] (x) The system according to any of the preceding or hereafter described aspects, wherein the line valve comprises a one-way valve configured to substantially prevent flow of said line cleansing gas to said analyzer.

[0046] (xi) The system according to any of the preceding or hereafter described aspects, wherein the system further comprises a probe cleansing assembly, the probe cleansing assembly including a probe cleansing gas source configured to supply a preselected stored volume of probe cleansing gas at pressure selected at between about 3BAR and 10BAR, and preferably between about 7 to 10 BARBAR, the probe cleansing gas source being in selective fluidic communication with the hollow interior of the probe via a probe inlet port spaced towards the proximal end portion, and a probe valve selectively actuable to effect flow of the volume of probe cleansing gas as a gas burst creating shockwave into the probe interior via the probe inlet port.

[0047] (xii) The system according to any of the preceding or hereafter described aspects, wherein the preselected volume of probe cleansing gas is selected at between about 51 and 301, preferably about 51, and / or is provided for supply as a high velocity gas burst for effecting shockwave cleansing of said probe interior at a release flow rate of between greater than about 100 1 / s and preferably between about 200 to 2,500 1 / s.

[0048] (xiii) The system according to any of the preceding or hereafter described aspects, wherein the probe cleansing gas source comprises a high-pressure reservoir tank.

[0049] (xiv) The system according to any of the preceding or hereafter described aspects, further including a gas filter assembly in fluid communication with said gas supply line, the filter assembly including a filter element for filtering dust or debris from said sampled gas disposed in a downstream position, interposed between said inlet port and said gas analyzer.

[0050] (xv) The system according to any of the preceding or hereafter described aspects, wherein the line cleansing gas source comprises a high-pressure reservoir tank. (xvi) The system according to any of the preceding or hereafter described aspects, wherein at least one of said line cleansing gas and said probe cleansing gas comprises of an inert gas such as N? or Argon or alternatively air.

[0051] (xvii) The system according to any of the preceding or hereafter described aspects, wherein the preselected volume of pressurized stored line cleansing gas is selected at between about 2 and 401, preferably about 25 and 301, and most preferably about 301, and / or the line cleansing assembly is operable to supply said preselected volume of line cleansing gas as a high velocity gas burst for effecting shockwave cleansing of said sampling tube and / or said gas supply line at a release flow rate of between greater than about 100 1 / s, preferably between about 200 and 2,500 l / s.

[0052] (xviii) The system according to any of the preceding or hereafter described aspects, further including a controller operable to control gas cleaning by: a) activating said line valve to effect the flow of line cleansing gas into the supply line at a first time period; and b) at a second time period, activating said probe valve to effect the flow of probe cleansing gas into the probe interior, the second time period being selected substantially concurrent with or about 1 to 10 seconds following the first time period

[0053] (xix) The system according to any of the preceding or hereafter described aspects, wherein the controller is operable to activate said line valve and / or said probe valve for a timed period selected less than about 2 seconds, preferably less than about 1 seconds, most preferably at or less than about 0.1 to 0.5 seconds and / or repeat steps a) and b) at timed intervals selected at between about 5 and 15 minutes, and preferably between about 8 and

[0054] 10 minutes.

[0055] (xx) The system according to any of the preceding or hereafter described aspects, wherein the controller is operable to further independently activate said line valve and / or said probe valve with differing frequencies, and preferably in dependence on the steel furnace process parameters. (xxi) The system according to any of the preceding or hereafter described aspects, wherein said inlet port is spaced less than about 10 meters from the open distal end of said sampling tube.

[0056] (xxii) The system according to any of the preceding or hereafter described aspects, wherein the industrial furnace off-gas stream is a steelmaking furnace off-gas stream moving through a steel furnace exhaust duct, the probe open distal end being disposed in the exhaust duct in at least a partially downwardly open orientation.

[0057] (xxiii) The system according to any of the preceding or hereafter described aspects, wherein the filter assembly is spaced from said exhaust duct by a distance selected at between about 5 and 15 meters and preferably about 8 to 10 meters, and said filter element comprises a replacement fabric sock filter or a stainless steel mesh filter.

[0058] (xxiv) The system according to any of the preceding or hereafter described aspects, wherein the gas supply line comprises an externally heated copper or Teflon1'1line having a diameter selected at between about 0.5 and 4 cm, preferably about 0.5 and 3.5 cm, and most preferably about 0.7 to 1.25 cm.

[0059] (xxv) The system according to any of the preceding or hereafter described aspects, wherein the probe has a longitudinal length selected at between about 1 meter and 2.5 meters, preferably between about 1 meter and 1.5 meters, and the hollow interior has a lateral diameter selected at between about 5 and 15 cm, and preferably between about 7 to 10 cm.

[0060] (xxvi) The system according to any of the preceding or hereafter described aspects, wherein the tubular outer sidewall comprises a fluid cooled double walled sidewall and extends concentrically about and is spaced from said gas sampling tube.

[0061] (xxvii) The system according to any of the preceding or hereafter described aspects, wherein the line valve and / or the probe valve comprises a solenoid valve, or a quick release piston valve.

[0062] (xxviii)The system according to any of the preceding or hereafter described aspects, wherein the line cleansing assembly includes a first valve assembly selectively activatable to effect flow of the preselected volume of line cleansing gas into said gas supply line via an inlet port intermediate said outlet end and said gas analyzer, the inlet port being spaced 0.5 meters to about 8 meters and preferably about 5 meters to about 7 meters from said outlet end, and wherein the probe cleansing assembly includes a second valve assembly selectively activatable to effect flow of the preselected volume of probe cleansing gas into said probe interior via an inlet spaced towards said proximal end.

[0063] (xxix) The system according to any of the preceding or hereafter described aspects, wherein the line cleansing assembly includes a first valve assembly operable to effect the flow of the preselected volume of line cleansing gas into said supply line as a high velocity gas burst for effecting shockwave cleansing at said gas sampling tube and / or said gas supply line at a release flow rate selected at between about 1 and 300 1 / s, preferably between about 10 and 100 1 / s or more.

[0064] (xxx) The system according to any of the preceding or hereafter described aspects, wherein the probe cleansing assembly includes a second valve assembly operable to effect the flow of the preselected volume of probe cleansing gas into said probe interior as a high velocity gas burst for effecting shockwave cleansing of said probe interior at a release flow rate selected at between about 5 and 300 1 / s, and preferably between about 10 and 100 1 / s, more preferably about 10 1 / s and 50 1 / s.

[0065] (xxxi) The system according to any of the preceding or hereafter described aspects, wherein the gas supply line comprises a heated line, and the distance is selected at between about 1 and 10 meters, preferably between about 3 and 9 meters and most preferably about 7 meters.

[0066] (xxxii) The system according to any of the preceding or hereafter described aspects, wherein the probe has a longitudinal length selected at between about 1 meter and 2.5 meters, preferably between about 1 meter and 1 .5 meters, and the hollow interior has a lateral diameter selected at between about 5 and 15 cm, and preferably between about 7 to 10 cm.

[0067] (xxxiii)The system according to any of the preceding or hereafter described aspects, wherein the furnace off-gas comprises an EAF furnace, BOF furnace off-gas and the flue duct comprises steelmaking furnace flue duct. (xxxiv)The system according to any of the preceding or hereafter described aspects, wherein the first valve assembly and / or second valve assembly comprises a solenoid valve, a diaphragm valve, a piston valve, or a quick release valve.

[0068] (xxxv) The system according to any of the preceding or hereafter described aspects, wherein the controller is operable to activate said first valve assembly and / or said second valve assembly for a timed period selected less than about 2 seconds, preferably less than about 1 second, and most preferably at or less than about 0.1 to 0.5 seconds and / or repeat steps a) and b) at timed intervals selected at between about 5 and 15 minutes, and preferably between about 8 and 10 minutes.

[0069] (xxxvi)The system according to any of the preceding or hereafter described aspects, wherein at least one of said line cleansing gas and said probe cleansing gas comprises of an inert gas such N2 or air.

[0070] (xxxvii) The system according to any of the preceding or hereafter described aspects, wherein the line valve is operable to effect the flow of the high velocity gas burst into said supply line to effect shockwave cleansing of the gas supply line and / or sampling tube thereby at a release flow rate selected at least between about 1 and 500 1 / s, preferably between about 6 and 300 1 / s, and preferably between about 10 and 200 1 / s.

[0071] (xxxviii) The system according to any of the preceding or hereafter described aspects, wherein the gas supply line comprises a heated line, and the distance is selected at between about 1 and 10 meters, preferably between about 3 and 9 meters and most preferably about 8 meters.

[0072] (xxxix)The system according to any of the preceding or hereafter described aspects, wherein the line valve comprises a one-way valve, and preferably a quick release valve, a diaphragm valve, a solenoid valve or a piston valve, configured to substantially prevent flow of said line cleansing gas to said analyzer assembly.

[0073] (xl) The system according to any of the preceding or hereafter described aspects, wherein the system further comprises a probe cleansing assembly, the probe cleansing assembly including a probe cleansing gas source configured to introduce a preselected volume of probe cleansing gas as a high pressure gas burst into the probe interior at pressure selected at between about 3BAR and 10BAR, and preferably about 7BAR, the probe cleansing gas source being in selective fluidic communication with the hollow interior of the probe via a probe inlet port spaced towards the proximal end, and a probe valve selectively actuable to effect flow of the volume of probe cleansing gas into the probe interior via the probe inlet port.

[0074] (xli) The system according to any of the preceding or hereafter described aspects, wherein the preselected stored volume of probe cleansing gas is selected at between about 51 and 301, and / or is provided for supply at a flow rate of between about 2 and 300 1 / s, preferably about 5 and 100 1 / s, and most preferably between about 10 and 40 1 / s.

[0075] (xlii) The system according to any of the preceding or hereafter described aspects, wherein at least one of said line cleansing gas and said probe cleansing gas comprises an inert gas such as N2 or air.

[0076] (xliii) The system according to any of the preceding or hereafter described aspects, wherein the preselected volume of probe cleansing gas is selected at between about 51 and 301, and the probe valve is operable to supply the volume of probe cleansing gas at a velocity selected to effect shockwave cleansing of said probe interior at a release flow rate of between about 1 and 300 1 / s, preferably about 5 and 10 1 / s, and most preferably between about 10 and 50 1 / s.

[0077] (xliv) The system according to any of the preceding or hereafter described aspects, wherein the valve assembly comprises a quick release valve configured to effect the flow of the analyzer cleansing gas at or towards said analyzer component and along said hollow interior as a shockwave.

[0078] (xlv) The system according to any of the preceding or hereafter described aspects, wherein the analyzer component comprises a gas sampling tube, and the tube comprises an extractive gas sampling probe.

[0079] (xlvi) The system according to any of the preceding or hereafter described aspects, wherein the gas analyzer comprises a TDLAS gas analyzer, and the analyzer component is selected from the group consisting of a laser beam emitter, a laser beam receptor and an optic window for a laser beam emitter or a laser beam receptor. (xlvii) The system according to any of the preceding or hereafter described aspects, wherein the gas analyzer comprises an IR analyzer or a FTIR analyzer, and the analyzer component is selected from the group consisting of an infrared sensor and an optic window for an infrared sensor.

[0080] (xlviii) The system according to any of the preceding or hereafter described aspects, wherein the valve assembly comprises a quick release valve configured to create a shockwave disturbance resulting from the high speed release of a relatively small volume of high pressure cleansing gas with said shock being directed at or to the analyzer system device component to dislodge, break apart and remove agglomerated build up from along the hollow interior of TDLAS shielding probes, the hollow interior of extractive probe assemblies including inner sampling tubes and gas supply lines and from the face of optical windows.

[0081] (xlix) The system according to any of the preceding or hereafter described aspects, wherein the line valve comprises a one-way valve configured to substantially prevent flow of said line cleansing gas to said analyzer.

[0082] (1) The system according to any of the preceding or hereafter described aspects, wherein the system further comprises a probe cleansing assembly, the probe cleansing assembly including a probe cleansing gas source configured to supply a shockwave from a preselected stored or relatively small volume of probe cleansing gas, preferably of about 5 and 301 at a pressure selected at between about 3BAR and 10BAR, and preferably between about 5 and 8BAR, and / or the probe cleansing gas source being in selective fluidic communication with the hollow interior of the probe via a probe inlet port spaced towards the proximal end portion, and a probe valve selectively actuable to effect a shockwave by the sudden release of the pressurized volume of probe cleansing gas into the probe interior via the probe inlet port.

[0083] (li) The system according to any of the preceding or hereafter described aspects, wherein the preselected stored, and preferably relatively small volume of cleansing gas, preferably of about 5 and 301, is maintained in pressurized a tank up to about 35 liters in size at pressures up to about 10BAR, and wherein the cleansing gas is released from said tank over a short time interval of less than about 0.5 seconds with sufficient disruptive intensity so as to create a shockwave front that is capable of dislodging and removing large, dense agglomerates that collect and build up in various analytical system devices used to analyze industrial gases most particularly from metallurgical and steelmaking furnace as defined herein.

[0084] (Hi) The system according to any of the preceding or hereafter described aspects, wherein the analytical system device cleansing gas source comprises a high-pressure reservoir tank.

[0085] (liii) The system according to any of the preceding or hereafter described aspects for gas extraction analysis, further including a gas filter assembly in fluid communication with said gas supply line, the filter assembly including a filter element for filtering dust or debris from said sampled gas disposed in a downstream position, interposed between said inlet port and said gas analyzer.

[0086] (liv) The system according to any of the preceding or hereafter described aspects, wherein the line cleansing gas source comprises a high-pressure reservoir tank.

[0087] (Iv) The system according to any of the preceding or hereafter described aspects, wherein at least one of said line cleansing gas and said probe cleansing gas comprises of an inert gas such as N2 or Ar or alternatively air.

[0088] (Ivi) The system according to any of the preceding or hereafter described aspects, wherein the preselected high pressure reservoir tank volume of line cleansing gas is selected at between about 2 and 40 liters, preferably 5 and 35 liters, most preferably about 5 and 30 liters and / or is supplied as a line cleansing shockwave resulting from the sudden release of high pressure gas from the reservoir tank gas flow over a time period selected less than about 1 second, or at less than about 0.5 second, or at or less than about 0. 1 second, and / or the line cleansing assembly is operable to supply said preselected volume of line cleansing gas as a high velocity gas burst for effecting shockwave cleansing of the gas supply line and / or sampling tube at a release flow rate of between greater than about 100 1 / s and preferably between about 200 to 3,000 I / s.

[0089] (Ivii) The system according to any of the preceding or hereafter described aspects, further including a controller operable to control gas cleaning by: a) activating said line valve to effect the shockwave creating flow of line cleansing gas into the supply line at a first time period; and b) at a second time period, activating said probe valve to effect the flow of shockwave creating probe cleansing gas into the probe interior, the second time period being selected substantially concurrent with or about 1 to 10 seconds following the first time period.

[0090] (Iviii) The system according to any of the preceding or hereafter described aspects, wherein the controller is operable to activate said line valve and / or said probe valve for a timed period selected less than about 1 second, preferably less than about 0.5 seconds, more preferably at or less than about 0.1 seconds and / or repeat steps a) and b) at timed intervals selected at between about 5 and 15 minutes, and preferably between about 8 and 10 minutes or at a time interval that is required to keep the analytical system devices fully operational.

[0091] (lix) The system according to any of the preceding or hereafter described aspects, wherein the controller is operable to further independently activate said line valve and / or said probe valve with differing frequencies, and preferably in dependence on the metallurgical or steel furnace process parameters.

[0092] (lx) The system according to any of the preceding or hereafter described aspects, wherein said inlet port is spaced less than about 10 meters, preferably less than about 8 meters and most preferably less than about 3 meters from the open distal end of said sampling tube.

[0093] (Ixi) The system according to any of the preceding or hereafter described aspects, wherein the industrial furnace off-gas stream is a steelmaking furnace off-gas stream moving through a steel furnace exhaust duct, the probe open distal end being disposed in the exhaust duct in a range between downwardly open and horizontally open orientations.

[0094] (Ixii) The system according to any of the preceding or hereafter described aspects, wherein the extraction system filter assembly is spaced from said exhaust duct in an easily accessible location by a distance of typically but not necessarily between about 5 and 15 meters and preferably about 7 to 10 meters, and most preferably about 8 meters and / or said filter element comprises preferably a replacement fabric sock or fabric or paper filter.

[0095] (Ixiii) The system according to any of the preceding or hereafter described aspects, wherein the extraction gas supply line comprises a Teflon™ or copper gas supply line, and preferably a heated copper or Teflon™ line and / or has an interior diameter selected at between about 0.5 and 4 cm, preferably about 0.5 and 3.5 cm, and most preferably 0.7 to 1 .2 cm.

[0096] (Ixiv) The system according to any of the preceding or hereafter described aspects, wherein the probe has a longitudinal length selected at between about 1 meter and 2.5 meters, preferably between about 1 meter and 1 .5 meters, and / or the hollow interior has a lateral diameter selected at between about 5 and 15 cm, and preferably between about 7 to 10 cm.

[0097] (Ixv) The system according to any of the preceding or hereafter described aspects, wherein the tubular outer sidewall probe comprises a fluid cooled double walled sidewall and / or preferably extends concentrically about and is spaced from said gas sampling tube.

[0098] (Ixvi) The system according to any of the preceding or hereafter described aspects, wherein the line valve and / or the probe valve comprise a solenoid valve or a quick release piston or diaphragm valve or the like capable of releasing the gas from a pressurized reservoir tank in less than about 0.5 seconds and preferably between about 0. 15 to 0.09 seconds.

[0099] (Ixvii)The system according to any of the preceding or hereafter described aspects, wherein the line cleansing assembly includes a first valve assembly selectively activatable to effect the sudden release flow of the preselected volume of line cleansing gas into said gas supply line via an inlet port intermediate said outlet end and said gas analyzer, the inlet port being spaced 0.5 meters to about 8 meters and preferably about 5 meters to about 7 meters from said outlet end, anchor wherein the probe cleansing assembly includes a second valve assembly selectively activatable to effect flow of the preselected volume of probe cleansing gas into said probe interior via an inlet port spaced towards said proximal end. (Ixviii) The system according to any of the preceding or hereafter described aspects, wherein the line cleansing assembly includes a first valve assembly operable to effect the sudden release flow of the preselected stored or relatively small volume of line cleansing gas into said supply line at a release flow rate selected at greater than about 100 1 / s and preferably between about 200 to 3,000 1 / s and most preferably as a high velocity, high pressure shockwave selected to dislodge and / or displace dust and agglomerated material from the extractive system gas supply line and / or extraction probe and / or extractive system sampling tube and / or from the TDLAS shielding probes and / or from the face of the TDLAS and IR / FTIR optical windows.

[0100] (Ixix) The system according to any of the preceding or hereafter described aspects, wherein the extractive and shielding probe cleansing or optical window cleansing assembly includes second valve assembly operable to effect the sudden release flow of the preselected relatively small volume of cleansing gas into said probe interior or along the face of said optical window as a high velocity gas burst for effecting shockwave cleansing of the probe interior or optical window face at a release flow rate selected greater than about 100 1 / s and preferably between about 200 to 3,000 1 / s.

[0101] (Ixx) The system according to any of the preceding or hereafter described aspects, wherein the extraction gas supply line comprises a heated line, and the distance is selected at between about 1 and 10 meters, preferably between about 3 and 9 meters and most preferably about 8 meters.

[0102] (Ixxi) The system according to any of the preceding or hereafter described aspects, wherein the probe has a longitudinal length selected at between about 1 meter and 2.5 meters, preferably between about 1 meter and 1 .5 meters, and / or the hollow interior has a lateral diameter selected at between about 5 and 15 cm, and preferably between about 7 to 10 cm.

[0103] (Ixxii) The system according to any of the preceding or hereafter described aspects, wherein the furnace comprises an EAF furnace, or a B OF furnace and the flue duct comprises steelmaking furnace flue duct. (Ixxiii) The system according to any of the preceding or hereafter described aspects, wherein the first valve assembly and / or second valve assembly comprises a solenoid valve, a quick release valve, a diaphragm valve and / or a piston valve and / or the like.

[0104] (Ixxiv) The system according to any of the preceding or hereafter described aspects, wherein the controller is operable to activate said first valve assembly and / or said second valve assembly for a timed gas release period selected less than about 1 second, preferably less than about 0.5 seconds, preferably at or less than about 0.1 to 0.15 seconds and / or repeat steps a) and b) at timed intervals selected at between about 5 and 15 minutes, and preferably between about 8 and 10 minutes or at any other time intervals as may be required to keep the analytical system devices fully operative.

[0105] (Ixxv) The system according to any of the preceding or hereafter described aspects, wherein the line valve is operable to effect the flow of the preselected volume of line cleansing gas into said supply line at a release flow rate selected at greater than 100 1 / s and preferably between 200 to 3,000 1 / s.

[0106] (Ixxvi) The system according to any of the preceding or hereafter described aspects, wherein the extraction system gas supply line comprises a heated line, and the distance is selected at between about 1 and 10 meters, preferably between about 3 and 9 meters and most preferably about 8 meters.

[0107] (Ixxvii) The system according to any of the preceding or hereafter described aspects, wherein the line valve comprises a one-way valve, and preferably a solenoid valve, a quick release valve, a diaphragm valve or a piston valve, or the like, configured to substantially prevent flow of said line cleansing gas to said extractive analyzer.

[0108] (Ixxviii) The system according to any of the preceding or hereafter described aspects, wherein the extractive probe or the TDLAS probe are cleaned with a direct connect shockwave apparatus wherein a preselected volume of the reservoir tank used for maintaining a stored, and preferably relatively small volume of the probe cleansing gas, and preferably a volume of about 5 and 301 is selected at between about 5 and 10 liters and preferably 5 liters and maintains the cleansing gas pressure preferably between 7 to 10BAR and is provided for supply at a release flow rate of greater than 100 l / s and preferably between 200 to 3,000 1 / s so as to effect a shockwave front upon release of said cleansing gas.

[0109] (Ixxix) The system according to any of the preceding or hereafter described aspects, wherein the system further comprises an extractive probe cleansing assembly and / or a TDLAS shielding probe cleansing assembly wherein said probe cleansing assembly includes a probe cleansing gas source configured to supply a preselected volume of probe cleansing gas at pressure selected at between about 3 and 10BAR, and preferably between about 5 and 10BAR, the probe cleansing gas source being in selective fluidic communication with the hollow interior of the probe via a probe inlet port spaced towards the proximal end portion, and a probe valve selectively actuable to effect flow of the volume of probe cleansing gas into the probe interior via the probe inlet port, and preferably as a high pressure shockwave selected to dislodge and / or displace dust and / or agglomerated material from the probe interior.

[0110] (Ixxx) The system according to any of the preceding or hereafter described aspects, wherein the gas analyzer comprises a TDLAS gas analyzer, and the analyzer component is selected from the group consisting of a laser beam emitter, a laser beam receptor and an optic window for a laser beam emitter or a laser beam receptor.

[0111] (Ixxxi) The system according to any of the preceding or hereafter described aspects, wherein the gas analyzer comprises an IR or FTIR analyzer, and the analyzer component is selected from the group consisting of an infrared sensor and an optic window for an infrared sensor.

[0112] BRIEF DESCRIPTION OF THE DRAWINGS

[0113] Reference may now be had to the following detailed description, taken together with the accompanying drawings, in which:

[0114] Figure 1 shows schematically a steel making furnace installation which incorporates an extractive gas analyzer system for analyzing furnace off-gases, which incorporates a high velocity gas cleansing system for effecting shockwave cleansing of analyzed components in accordance with a preferred embodiment of the invention;

[0115] IT Figure 2 illustrates schematically the extractive gas analyzer system of Figure 1 , illustrating the probe outer sidewall and sampling tube;

[0116] Figure 3 illustrates an example output of off-gas constituent values detected in the operation of the EAF furnace installation of Figure 1 , while periodically effecting gas supply line and probe cleansing operations;

[0117] Figure 4 illustrates schematically a tunable diode laser analyzer system for the analysis of furnace off-gases, and which incorporates a high velocity gas cleansing system in accordance with a further embodiment of the invention; and

[0118] Figure 5 illustrates schematically an IR / Fourier Transfer IR sensor analysis system used in the analysis of furnace off-gas constituents, and which incorporates a high velocity gas cleansing system in accordance with a further embodiment.

[0119] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0120] Reference may be had to Figure 1 which illustrates a basic oxygen furnace (BOF) steelmaking furnace installation 10 which incorporates an extractive gas analyzer system 30 in accordance with a preferred embodiment of the invention. The BOF furnace installation 10 includes a hearth 12 for melting charged materials 14 by way of an electrode 16. Furnace off-gases produced in the hearth 12 are exhausted by way of furnace outlet 18 via an exhaust flue duct 20 as an exhaust off-gas flow 100.

[0121] As will be described, the extractive gas analyzer system 30 is configured to extract and monitor sampled off-gases flowing through the flue duct 20 to obtain measurements of constituent off-gas components, and typically CO, CO2, Hz, O2and / or H2O, as indicators of hearth 12 operating conditions. Depending on the gas constituents detected, the gas analyzer system 30 may be used to control hearth 12 and furnace operating parameters, including charging material types and rates, heat times, electric current supplied to the electrode 16, oxygen inputs and the like, to better maximize melt efficiencies and / or optimize furnace environmental controls.

[0122] Figures 1 and 2 illustrate schematically the gas analyzer system 30 shown in

[0123] Figure 1 . The gas analyzer system 30 includes a gas sampling probe 32, a gas analyzer assembly 34, a gas supply line 36 fluidically communicating the probe 32 and the gas analyzer assembly 34, a line cleansing assembly 38, a probe cleansing assembly 40, and a controller 50. The line cleansing assembly 38 and probe cleansing assembly 40 are each provided for selective fluid communication with a bulk cleansing gas (consisting of air or an inert gas such as N2 or argon) supply 44 via respective gas feed lines 48,46

[0124] Figure 2 shows the probe 32 as provided with a double walled outer sidewall 60 which extends axially as a cylindrical tube having a longitudinal length of about 1 .5 meters. The sidewall 60 extends from a substantially sealed proximal end 62 to a lower open distal end 64, defining a smooth walled hollow probe interior 66 having a lateral diameter of between about 7 and 15 cm. Preferably, the interior of the double sidewall 60 is divided into at least one fluid flow channel 68. The fluid flow channel 68 is adapted to receive a flow of coolant water from a suitable coolant source 70.

[0125] A longitudinally elongated sampling tube 72 is coaxially mounted in the probe interior 66. The sampling tube 72 extends axially through the sealed proximal end 62 to a distal most inlet end 74. Preferably the sampling tube 72 is positioned with the inlet end 74 spaced inwardly in the probe interior 66 from the open distal end 64 by a distance of between about 10 and 20 cm. Although not essential, in a most preferred construction, the sampling tube 72 is provided as an open ended cylindrical metal tube having an inner diameter selected at between about 0.5 and 3 cm, preferably 0.5 and 1 cm, and an axial length of about 1 .5 meters.

[0126] Figure 2 shows the gas supply line 36 as being fluidically coupled to an upper outlet end 76 of the sampling tube 72 by way of threaded coupling. Preferably, the gas supply line 36 is provided as a heated copper or Teflon™ tubular line having an internal diameter selected at between about 0.5 and 3 cm, and most preferably between about 0.5 and 1 cm. Non-heated lines may also be used. In one non-limiting construction heating strips or coils may be imbedded in or in thermal contact about the tubular line. The heating strips or coils are activatable to maintain the sampled furnace gases flow 200 moving through the gas supply line 36 at a preselected temperature, and most preferably a temperature selected above the dew point of the constituent gas component species to be analyzed. Figures 1 and 2 illustrate the gas supply line 36 as providing fluid communication between the sampling probe 32 and the gas analyzer assembly 34 via a prefilter 80. As will be described, sampled gas flow 200 extracted from the off-gas flow 100 moving through the duct 20 thus moves via the sampling probe 32, through the prefilter 80 and is filtered prior to analysis in the gas analyzer assembly 34, to remove any entrained dust or particulate matter therein. Although not essential, most preferably, the prefilter 80 is provided at at least 2 meters, and preferably about 5 to 8 meters from the flue duct 20. The applicant has appreciated that the remote positioning of the prefilter 80 advantageously facilitates filter replacement and system maintenance, allowing filter replacement in an area separated from the flue duct 20 and the associated high temperature furnace off-gases. Furthermore, because the prefilter 80 is located a distance spaced from the heat associated with the flue duct 20 and off-gas flow 100, larger and / or more conventional bag filters may be used as suitable filter media, in place of more expensive stainless steel metal filter constructions.

[0127] Figure 2 shows best the gas analyzer assembly 34 as including an internal reversable vacuum pump 90, one or more constituent analyzer cells 92 and the controller 50. Whilst the controller 50 is illustrated as part of the gas analyzer assembly 34, it is to be appreciated that in alternate constructions, the controller 50 could be provided as a separate or stand-alone processor or central processing unit (CPU). The vacuum pump 90 fluidically communicates with both the gas supply line 36 and analyzer cell 92. In a sampling and analysis mode, the vacuum pump 90 is operable to draw sampled off-gas from the off-gas stream 100 into the probe gas sampling tube 72 and along the gas supply line 36 and through the prefilter 80 in the direction of arrow 200 for constituent analysis by way of the analyzer cell 92. In a most preferred construction, the vacuum pump 90 is also provided for selective communication with the cleansing gas supply 44, and is operable in a reverse manner to effect conventional supply line and probe cleansing operations during furnace shut down.

[0128] Figure 2 illustrates best the line cleansing assembly 38 as including a compressor 94, a gas pressurization tank 96 and a valve assembly 98. The compressor 94 is provided in fluid communication with the gas feed line 46 for receiving cleansing gas from the cleansing gas supply 44 to effect cleansing of the gas supply line 36 and gas sampling tube 72. The pressurization tank 96 is configured to store a preselected volume of cleansing gas pressurized by the compressor 94. Preferably, the pressurization tank 96 and compressor 94 are configured to pressurize and store in the pressurization tank 96 a preselected stored volume VLof line cleansing gas of between 5 and 301, and typically about 301 at a stored pressure of between 3 to 10 BAR and preferably between 7 to 10 BAR.

[0129] The valve assembly 98 is positioned to selectively fluidically communicate the pressurization tank 96 with the gas supply line 36. Most preferably, the valve assembly 98 includes solenoid and diaphragm valve which when operated, permit almost instantaneous a one-way gas flow 300 from the pressurization tank 96 and into and along the gas supply line 36 and from the probe gas sampling tube 72 as a high velocity cleaning flow in the reverse flow direction only.

[0130] In a most preferred arrangement, the one-way valve assembly 98 is positioned to fluidically communicate the line cleansing assembly pressurization tank 96 with the gas supply line 36 in a location immediately upstream from the prefilter 80. With such an orientation, valve assembly 98 may be operated to effect the cleansing gas flow 300 as a high pressure gas burst along substantially the entirety of the length gas supply line 36 upstream from the prefilter 80, and outwardly from the sampling tube 72.

[0131] The valve assembly 98 is operated to release substantially the entirety of the stored volume of pressurized line cleansing gas VLstored in the pressure tank 96 in a period of less than 0.5 seconds and typically at or from less than about 0.1 to 0.2 seconds. Preferably, the stored volume of line cleansing gas Vi. is released at release flow rates that are typically of greater than 100 1 / s and preferably between 200 to 2,500 1 / s. The release flow rate is selected to effect gas expansion and the creation of a release volume flow 300 and shockwave along the supply line 36 and sampling tube 72 so as to dislodge dust and any agglomerated material therefrom. The released gas forms pressure wave moving in a reverse flow direction 300 along the supply line 36 and outwardly from the probe sampling tube 72 via the open distal end 74. Depending on the overall geometry and dimensions of the supply line 36 and sampling tube 72 interior, typically the valve assembly 98 is actuated to release the entire stored volume of pressurized line cleansing gas VLat a release flow rate of at least about 100 1 / s and preferably between about 200 to 2,500 1 / s. The initial pressurization of the stored volume VLof line cleansing gas in the pressurization tank 96 and rate of flow 300 are most preferably selected such that the formed pressure wave is characterized by a steep or shockwave front which propagates longitudinally along the entire length of the gas supply line 36 and outwardly from the sampling tube 72. The line cleansing assembly 30 may thus be periodically operated to rapidly dislodge any dust, and preferably any adhered or agglomerated molten slag which has been drawn into the sampling tube 72 and / or gas supply line 36 without receiving significant interruption in gas sampling procedures.

[0132] In a preferred construction, the pressurization tank 96 and line cleansing valve assembly 98 are oriented to provide for the introduction of the stored volume of pressurized line cleansing gas VLinto the gas supply line 36, so that the distance of travel of the resulting compression wave prior to exiting the open distal end 74 equal to or is less than about 8 meters and preferably less than about 5 meters.

[0133] Figure 2 shows the probe cleansing assembly 40 as including a compressor 102, an associated gas pressurization tank 104 and a second valve assembly 106. The compressor 102 is provided in fluid communication with the gas feed line 48 for receiving cleansing gas from the cleansing gas supply 44 to effect cleansing of the probe interior 66. The pressurization tank 104 is configured to store a preselected stored volume Vp of probe cleansing gas pressurized by the compressor 102. Preferably, the compressor 102 and pressurization tank 104 are configured to pressurize and store in the pressurization tank 104, a preselected stored volume Vp of between 51 and 301, at a stored pressure of about 7 to 10BAR. Although not essential, in a simplified construction, the pressurization tank 104 may be mounted immediately adjacent the probe proximal end 62. Such an arrangement minimizes the path of fluid flow travel between the tank 104 and probe interior 66, allowing smaller probe cleansing gas volume Vp to be used.

[0134] The valve assembly 106 is positioned to selectively fluidically communicate the pressurization tank 104 with a proximal-most region of the tube interior 66. Most preferably, the valve assembly 106 includes solenoid and diaphragm valves which when operated, effect one-way gas flow 400 as a high velocity gas burst from the pressurization tank 104 via an outlet port 108 adjacent the proximal end 62. The gas flow 400 preferably probes as a separate shockwave along the probe interior 66, dislodging both dust and agglomerated material therefrom. The gas flow 400 moves as a pressure wave from the port 108 and into and downwardly along the probe interior 66 from the probe distal end 64 as a cleansing flow 400.

[0135] The valve assembly 106 is operated to release the pressurized probe cleansing gas Vp stored in the pressure tank 104 over a period of preferably less than about 0.5 seconds, more preferably at or less than about 0.15 seconds. Preferably, the stored volume of probe cleansing gas Vp is released with a flow rate selected to effect expansion and the creation of pressure wave downwardly along the probe interior as a cleansing release volume flow 400, and outwardly from the open distal end 64. With the overall geometry and dimensions of the probe interior 66, typically the valve assembly 106 is actuated to release the entire volume of pressurized probe cleansing gas Vp at a release flow rate of greater than about 1001 / s and preferably about 200 to 2,500 1 / s. The initial pressurization of the stored volume Vp of probe cleansing gas in the pressurization tank 104 and rate of flow 400 are most preferably selected such that the formed pressure wave is characterized by a steep or shockwave front which propagates longitudinally downward along the entire length of the probe interior 66, substantially from the proximal end 62 and outwardly from the distal end 62. The probe cleansing assembly 40 may thus be used periodically to rapidly dislodge any dust, and preferably any adhered or agglomerated molten slag which has been drawn into the probe interior 66, and which may adhere to the sidewall 60 and / or the exteriors of the sampling tube 72.

[0136] The applicant has appreciated that because the stored volumes VL, Vp of the line cleansing gas and probe cleansing gas are fully released over shortened time periods lasting preferably less than about 1 seconds, more preferably at or less than about 0.15 to 0.1 seconds. , cleansing of the supply line 36 and the sampling tube 72, as well as sampling probe interior 66 may be effected periodically during furnace heat operations and with minimal interruption to the process off-gas constituent monitoring and furnace control. The applicant has appreciated that the present invention advantageously may allow for rapid “shock” cleaning of the gas supply line and / or probe interior over shortened periods of time, and most preferably the time period for complete exhaust of the cleansing gas from the gas supply line and probe of less than about 10 seconds. As a result, with the present system periodic supply line 36 and / or probe 32 cleansing operations may be effected with only minimal interruption with gas analysis and extraction. In particular, the shorter cleansing times allow almost continuous gas analysis during a steel production heat, and whereby the individual time periods during which cleansing operations are effected are filtered from obtained data readings.

[0137] In a preferred embodiment, the controller 50 may be used to effect supply line 36 cleansing and probe 66 cleansing on a sensed basis, for example by using one or more optical sensors (not shown) positioned along the gas supply line 36, and which are operable to optically detect line obstructions. Alternately, cleansing operations may be effected at pre-timed intervals as for example, at times T1, T2, T3 preselected at every 8 to 15 minutes, and preferably 8 to 10 minutes, during steel making heats or at such intervals as needed to maintain uninterrupted operation of the specific analytical system device. Such timed intervals may further vary in frequency with particular steel production heat stages, and expected corresponding increases or decreases in slag splash or dust output.

[0138] In a typical mode of operation, the EAF hearth 12 is charged with selected charging materials 14, and the electrode 16 activated to effect melt operations. Concurrently, the extractive gas analyzer system 30 is operated whereby the vacuum pump 90 is used to draw sampled furnace off-gases from the off-gas stream 100 and into the probe distal end 64. The operation of the vacuum pump 90 draws the sampled off-gas into the sampling tube 72 and through the prefilter 80 via the gas supply line 36 as a sample off-gas stream 200, for the analysis off-gas constituents such as CO, CO2, H2, H2O and O2by the analyzer cell 92.

[0139] During steel melt operations by the hearth 12, the valve assemblies 98,106 are preferably periodically activated at preselected timed intervals T1,T2,T3to concurrently release the stored volumes of pressurized line cleansing gas VLand probe cleansing gas Vp as the cleansing gas flows 300,400, to dislodge dust and debris accumulating in the gas supply line 36 and sampling tube 72, as well as the probe interior 66. Following the discharge of the cleansing gas volumes VL,VP, the valve assemblies 98,106 are again closed, and the compressors 94 and 102 are activated to pressurize and respectively store in each gas pressurization tank 96,104, a next volume of pressurized line cleansing gas VLand probe cleansing gas Vp for use in a next cleansing operation. As noted, the valve assemblies 98,106 may be operated in concert on a timed basis at intervals T1,T2,T3, as for example periodically every 8 to 10 minutes. Although less preferred, in an alternative arrangement, the valve assemblies 98,106 may be operated on a sequenced basis, with a delay between valve operation, as for example of between about 1 and 10 seconds and / or with one of the valve assemblies 98,106 actuated with a higher frequency than the other.

[0140] Figure 3 illustrates an example output display showing detected off-gas constituent concentrations identified by the gas analyzer assembly 34 in the operation of the gas analyzer system 30. In the example, at times T1,T2,T3of gas supply line 36 and probe 32 cleansing as well in the 2 to 10 second period immediately following gas cleansing operations, the concentration of off-gas constituents detected may be less reliable, as a result of dilution and / or mixture of sampled off-gases and cleansing gases. Most preferably, the controller 50 is provided with suitable filtering software which operates to filter from constituent output readings and any associated furnace controls in response thereto, detected constituents readings during valve assembly 98,106 activation times T1,T2,T3and preferably for a period of 5 to 20 seconds immediately following each cleansing operation.

[0141] The applicant has appreciated that the extractive gas analyzer system 30 may thus be used to effect almost continuous extraction and analysis of sampled furnace off-gases, and provide suitable furnace signal controls to optimize hearth 12 efficiencies.

[0142] Although the detailed description describes the preferred embodiment of the invention as residing in a high velocity gas shockwave burst cleansing system for use with an extractive off-gas analyzer system 30, the invention is not so limited. It is to be appreciated that the gas burst system of the present invention may be used to effect the periodic cleaning of different types of analyzers, including without restriction tunable diode laser absorption spectroscopy (TDLAS) analyzers, as well as infrared (IR.) and Fourier-Transform infrared spectroscopy (FTIR) analyzers. In such arrangements, the gas burst shockwave system may be configured to supply the sudden release and output preselected pressurized volumes of cleansing gas across the face of optical windows adjoining optical emitters and / or receptacles so as to effect the shockwave cleansing and displacement of dust, debris and other agglomerated material accumulating thereon. Reference may be had to Figure 4 which illustrates a TDLAS gas analysis system 150 in accordance with an alternate embodiment of the invention, in which like reference numerals are used to identify like components.

[0143] The TDLAS gas analyzer system 150 is illustrated in Figure 4 as including a tunable diode laser beam emitter 152 and a laser beam receptor 154. Each of the emitter 152 and receptor 154 are positioned on opposing sides of a furnace flue duct 20, so as to respectively emit and detect a coherent light beam 155 directly across the off-gas flow 100. Each of the emitter 152 and receptor 154 are mounted within a proximal outer portion of a respective shielding tube 160a, 160b, which extends inwardly into the flue duct 20 to respective open distal ends 64.

[0144] The emitter 152 and receptor 154 are preferably maintained in isolation from the off-gas stream 100 flowing through the duct 20, by respective optic lenses or windows

[0145] 162.164.

[0146] The gas analyzer system 150 is provided with tube cleaning assembly 132 which is operable to selectively emit the sudden release of high pressure, high velocity gas flows longitudinally along the interior of each shielding tube 160a, 160b. The gas flows are selected to effect the shockwave cleaning of the tube 160a, 160b and optic windows

[0147] 162.164, and the dislodgement of any dust or agglomeration accumulating therein. The tube cleaning assembly 132 is preferably provided with a pair of pressurization tanks of approximately 5-30 liters in size 96,96’ which are each configured to pressurize and store therein a respective preselected volume VTof a suitable tube cleansing gas. The pressurization tanks 96,96’ are respectively provided in selective fluid communication with proximal end portions of each shielding tube 160a, 160b by way of associated valve assemblies 98,98’ and conduits. Most preferably, the pressurization tanks 96,96’ are oriented such that the actuation of the valve assemblies 98,98’ is such as to effect burst cleaning of the optic windows 162,164, and the discharge of a high velocity cleaning gas flow at each window 162,164 and along and outwardly from each shielding tube

[0148] 160a, 160b into the duct 20.

[0149] Reference may be had to Figure 5 which illustrates an IR / FTIR analyzer system 180 in accordance with a further embodiment of the invention, in which like reference numerals are used to identify like components. In the analyzer system 180 of Figure 5, an infrared (IR) sensor 174 is positioned within a suitable mounting flange tube 176. The mounting tube 176 is mounted to the side of a furnace flue duct 20 aligned with a duct opening 182 and open to the flue gas stream 100. The IR sensor 174 is sealed against the off-gas flow 100 travelling through the duct 20 by a suitable optical window 178.

[0150] An analyzer cleaning assembly 184 includes a pressurization tank 96 configures to store a preselected volume VLof suitable cleansing gas, and a valve assembly 98. Most preferably, the pressurization tank of 5 and 30 liters in size 96 is configured to store a preselected volume VTof inert gas such as nitrogen, or air at a pressure of approximately 3 to 10BAR and preferably 7 to 10BAR. The valve assembly 98 is actuable to output the stored volume VTof gas from the pressurization tank 98 as a high velocity gas burst adjacent to the optical window 178. The valve assembly 98 preferably is actuable to the entire volume of cleansing gas VTat a release flow rate at or at least about greater than 100 1 / s to effect shockwave cleaning of the optical window 178, and dislodge any dust or agglomerated materials thereon and from around the opening 182 which could otherwise obstruct or occlude the sensor 174.

[0151] Although the detailed description describes and illustrates various preferred embodiments in accordance with the best mode, the invention is not limited. Modifications and variations will now occur to persons skilled in the art.

Claims

We claim:1 . A gas analyzer cleansing system comprising, a longitudinally elongated gas sampling probe for extracting a gas sample, a gas supply line configured for supplying extracted sampled gas to a gas analyzer, and line cleansing assembly, the probe extending from a proximal end portion to an open distal end configured for positioning in an industrial furnace off-gas stream and comprising, a tubular outer sidewall extending from said proximal end portion to said distal end and defining a hollow interior, and a gas sampling tube extending longitudinal along said hollow interior, said sampling tube having an open inlet end spaced towards the distal end and an outlet end fluidically coupled to the gas supply line, the line cleansing assembly including a line cleansing gas source configured to supply a preselected volume of line cleansing gas at pressure selected at between about 3 BAR and 10BAR, and preferably about 7 to 10 BAR, the line cleansing gas source being in selective fluidic communication with the gas supply line via an inlet port intermediate said tube outlet end and said gas analyzer, and a line valve selectively actuable to effect flow of the volume of line cleansing gas into the gas supply line and from said gas sampling tube inlet end as a reverse gas burst line cleansing gas flow.

2. The gas analyzer system as claimed in claim 1, wherein the line valve comprises a one-way valve configured to substantially prevent flow of said line cleansing gas to said analyzer.

3. The gas analyzer system as claimed in claim 1 or claim 2, wherein the system further comprises a probe cleansing assembly,the probe cleansing assembly including a probe cleansing gas source configured to supply a preselected stored volume of probe cleansing gas at pressure selected at between about 3BAR and 10BAR, and preferably between about 7 to 10 BAR, the probe cleansing gas source being in selective fluidic communication with the hollow interior of the probe via a probe inlet port spaced towards the proximal end portion, and a probe valve selectively actuable to effect flow of the volume of probe cleansing gas as a gas burst creating shockwave into the probe interior via the probe inlet port.

4. The gas analyzer system as claimed in claim 3, wherein the preselected volume of probe cleansing gas is selected at between about 51 and 301, preferably about 51, and / or is provided for supply as a high velocity gas burst for effecting shockwave cleansing of said probe interior at a release flow rate of between greater than about 100 1 / s and preferably between about 200 to 2,500 1 / s.

5. The gas analyzer system as claimed in claim 3 or claim 4, wherein the probe cleansing gas source comprises a high-pressure reservoir tank.

6. The gas analyzer system as claimed in any one of claims 1 to 5, further including a gas filter assembly in fluid communication with said gas supply line, the filter assembly including a filter element for filtering dust or debris from said sampled gas disposed in a downstream position, interposed between said inlet port and said gas analyzer.

7. The gas analyzer system as claimed in any one of claims 1 to 6, wherein the line cleansing gas source comprises a high-pressure reservoir tank.

8. The gas analyzer system, as claimed in any one of claims 1 to 7, wherein at least one of said line cleansing gas and said probe cleansing gas comprises of an inert gas such as N2 or Argon or alternatively air.

9. The gas analyzer system as claimed in any one of claims 1 to 8, wherein the preselected volume of stored line cleansing gas is selected at between about 2 and 401, preferably about 25 and 301, and most preferably about 301, and / or the line cleansing assembly is operable to supply said preselected volume of line cleansing gas as a highvelocity gas burst for effecting shockwave cleansing of said sampling tube and / or said gas supply line at a release flow rate of between greater than about 100 1 / s, preferably between about 200 and 2,500 1 / s,.

10. The gas analyzer system as claimed in any one of claims 1 to 9, further including a controller operable to control gas cleaning by: a) activating said line valve to effect the flow of line cleansing gas into the supply line at a first time period; and b) at a second time period, activating said probe valve to effect the flow of probe cleansing gas into the probe interior, the second time period being selected substantially concurrent with or about 1 to 10 seconds following the first time period.1 1 . The gas analyzer system as claimed in claim 10, wherein the controller is operable to activate said line valve and / or said probe valve for a timed period selected less than about 2 seconds, preferably less than about 1 seconds, most preferably at or less than about 0.1 to 0.5 seconds and / or repeat steps a) and b) at timed intervals selected at between about 5 and 15 minutes, and preferably between about 8 and 10 minutes.

12. The gas analyzer system as claimed in claim 10 or claim 1 1, wherein the controller is operable to further independently activate said line valve and / or said probe valve with differing frequencies, and preferably in dependence on the steel furnace process parameters.

13. The gas analyzer system as claimed in any one of claims 1 to 12, wherein said inlet port is spaced less than about 10 meters from the proximal end of said probe.

14. The gas analyzer system as claimed in any one of claims 1 to 13, wherein the industrial furnace off-gas stream is a steelmaking furnace off-gas stream moving through a steel furnace exhaust duct, the probe open distal end being disposed in the exhaust duct in at least a partially downwardly open orientation.

15. The gas analyzer system as claimed in any one of claims 1 to 14, wherein the filter assembly is spaced from said exhaust duct by a distance selected at between about 5 and15 meters and preferably about 8 to 10 meters, and said filter element comprises a replacement fabric sock filter or a stainless steel mesh filter.

16. The gas analyzer system as claimed in any one of claims 1 to 15, wherein the gas supply line comprises an externally heated copper or Teflon™ line having a diameter selected at between about 0.5 and 4 cm, preferably about 0.5 and 3.5 cm, and most preferably about 0.7 to 1 .25 cm.

17. The gas analyzer system as claimed in any one of claims 1 to 16, wherein the probe has a longitudinal length selected at between about 1 meter and 2.5 meters, preferably between about 1 meter and 1.5 meters, and the hollow interior has a lateral diameter selected at between about 5 and 15 cm, and preferably between about 7 to 10 cm.

18. The gas analyzer system as claimed in any one of claims 1 to 17, wherein the tubular outer sidewall comprises a fluid cooled double walled sidewall and extends concentrically about and is spaced from said gas sampling tube.

19. The gas analyzer system as claimed in any one of claims 1 to 18, wherein the line valve and / or the probe valve comprises a solenoid valve, or a quick release piston valve.

20. An extractive gas analyzer system for analyzing a furnace off-gas flowing in a furnace flue duct, the analyzer system comprising, a gas sampling probe, the probe being elongated along a longitudinal axis and extending from an open distal end disposed in the furnace flue duct to a proximal end spaced outwardly therefrom, the probe comprising, an outer sidewall extending about said axis from the open distal end towards the proximal end and defining a hollow probe interior, and an elongated sampling tube disposed at least in part in said probe interior and extending generally along said axis from an inlet end open to said interior anddisposed towards said open distal end, to an outlet end disposed towards the proximal end, a gas supply line fluidically communicating the outlet end with a gas analyzer assembly spaced a distance from the furnace flue duct, the gas analyzer assembly being operable to draw said furnace off-gas from the flue duct into said sampling tube and along said supply line in a first flow direction for analysis, a line cleansing assembly selectively operable to introduce a preselected volume of pressurized line cleansing gas into said gas supply line as a line cleansing gas flow in a direction opposite said first flow direction, and wherein the preselected volume of pressurized line cleansing gas is stored at a volume selected at between about 11 and 401, preferably about 251 and 301, and has a pressure selected at between about 3BAR and 10BAR, preferably about 7 to 8BAR, a probe cleansing assembly selectively operable to introduce a preselected volume of pressurized probe cleansing gas into said probe interior as a probe cleansing gas flow in a direction outwardly from the open distal end, wherein the preselected volume of pressurized probe cleansing gas is stored at a volume selected at between about 51 and 501, preferably about 51 and 101, and has a pressure selected at between about 3BAR and 10BAR, preferably about 7 to 10BAR, and a controller for controlling the line cleansing assembly and probe cleansing assembly to selectively effect the line cleansing gas flow and / or probe cleansing gas flow.21 . The extractive gas analyzer system as claimed in claim 20, wherein the line cleansing assembly includes a first valve assembly selectively activatable to effect flow of the preselected volume of line cleansing gas into said gas supply line via an inlet port intermediate said outlet end and said gas analyzer, the inlet port being spaced 0.5 meters to about 8 meters and preferably about 5 meters to about 7 meters from said outlet end, and wherein the probe cleansing assembly includes a second valve assembly selectively activatable to effect flow of the preselected volume of probe cleansing gas into said probe interior via an inlet spaced towards said proximal end.

22. The extractive gas analyzer system as claimed in any one of claims 20 or 21 , wherein the line cleansing assembly includes a first valve assembly operable to effect the flow of the preselected volume of line cleansing gas into said supply line as a high velocity gas burst for effecting shockwave cleansing at said gas sampling tube and / or said gas supply line at a release flow rate selected at between about 1 and 300 1 / s, preferably between about 10 and 100 1 / s or more.

23. The extractive gas analyzer system as claimed in any one of claims 20 to 22, wherein the probe cleansing assembly includes second valve assembly operable to effect the flow of the preselected volume of probe cleansing gas into said probe interior as a high velocity gas burst for effecting shockwave cleansing of said probe interior at a release flow rate selected at between about 5 and 300 1 / s, and preferably between about 10 and 100 1 / s, more preferably about 10 1 / s and 50 1 / s.

24. The extractive gas analyzer system as claimed in any one of claims 20 to 23, wherein the gas supply line comprises a heated line, and the distance is selected at between about 1 and 10 meters, preferably between about 3 and 9 meters and most preferably about 7 meters.

25. The extractive gas analyzer system as claimed in any one of claims 20 to 24, wherein the probe has a longitudinal length selected at between about 1 meter and 2.5 meters, preferably between about 1 meter and 1 .5 meters, and the hollow interior has a lateral diameter selected at between about 5 and 15 cm, and preferably between about 7 to 10 cm.

26. The extractive gas analyzer system as claimed in any one of claims 20 to 24, wherein the furnace off-gas comprises an EAF furnace, BOF furnace off-gas and the flue duct comprises steelmaking furnace flue duct.

27. The extractive gas analyzer system as claimed in any one of claims 20 to 26, wherein the first valve assembly and / or second valve assembly comprises a solenoid valve, a diaphragm valve, a piston valve, or a quick release valve.

28. The extractive gas analyzer system as claimed in claim 27, wherein the controller is operable to activate said first valve assembly and / or said second valve assembly for a timed period selected less than about 2 seconds, preferably less than about 1 second, and most preferably at or less than about 0.1 to 0.5 seconds and / or repeat steps a) and b) at timed intervals selected at between about 5 and 15 minutes, and preferably between about 8 and 10 minutes.

29. The extractive gas analyzer system, as claimed in any one of claims 20 to 28, wherein at least one of said line cleansing gas and said probe cleansing gas comprises of an inert gas such N2 or air.

30. An extractive gas analyzer system for analyzing a furnace off-gas flowing in a furnace flue duct, the analyzer system comprising, a gas sampling probe, the probe being elongated along a longitudinal axis and extending from an open distal end disposed in the furnace flue duct to a proximal end spaced outwardly therefrom, the probe comprising, an outer sidewall extending about said axis from the open distal end towards the proximal end and defining a hollow probe interior, and an elongated sampling tube disposed at least in part in said probe interior and extending generally along said axis from an inlet end open to said interior and disposed towards said open distal end, to an outlet end disposed towards the proximal end, a gas supply line fluidically communicating the outlet end with a gas analyzer assembly spaced a distance from the furnace flue duct, the gas analyzer assembly being operable to draw said furnace off-gas from the flue duct into said sampling tube and along said supply line in a first flow direction for analysis, a line cleansing assembly selectively operable to introduce a preselected stored volume of pressurized line cleansing gas into said gas supply line as a high velocity gas burst in a direction opposite said first flow direction, and wherein the preselected stored volume of pressured line cleansing gas is selected at between about 21 and 401, preferablyabout 21 and 301, and has a pressure selected at between about 3BAR and 10BAR, preferably about 7 to 8BAR, a line valve selectively actuable to effect flow of the preselected stored volume of line cleansing gas into said gas supply line via an inlet port intermediate said outlet end and said gas analyzer, the inlet port being spaced 0.5 meters to about 8 meters and preferably about 5 meters to about 7 meters from said probe.31 . The extractive gas analyzer system as claimed in claim 30, wherein the line valve is operable to effect the flow of the high velocity gas burst into said supply line to effect shockwave cleansing of the gas supply line and / or sampling tube thereby at a release flow rate selected at at least between about 1 and 500 1 / s, preferably between about 6 and 300 1 / s, and preferably between about 10 and 200 1 / s.

32. The extractive gas analyzer system as claimed in claim 30 or claim 31 , wherein the gas supply line comprises a heated line, and the distance is selected at between about 1 and 10 meters, preferably between about 3 and 9 meters and most preferably about 8 meters.

33. The extractive gas analyzer system as claimed in any one of claims 30 to 32, wherein the line valve comprises a one-way valve, and preferably a quick release valve, a diaphragm valve, a solenoid valve or a piston valve, configured to substantially prevent flow of said line cleansing gas to said analyzer assembly.

34. The extractive gas analyzer system as claimed in any one of claims 30 to 33, wherein the system further comprises a probe cleansing assembly, the probe cleansing assembly including a probe cleansing gas source configured to introduce a preselected volume of probe cleansing gas as a high pressure gas burst into the probe interior at pressure selected at between about 3BAR and 10BAR, and preferably about 7BAR, the probe cleansing gas source being in selective fluidic communication with the hollow interior of the probe via a probe inlet port spaced towards the proximal end, and a probe valve selectively actuable to effect flow of the volume of probe cleansing gas into the probe interior via the probe inlet port.

35. The extractive gas analyzer system as claimed in claim 33, wherein the preselected stored volume of probe cleansing gas is selected at between about 51 and 301, and / or is provided for supply at a flow rate of between about 2 and 300 1 / s, preferably about 5 and 100 1 / s, and most preferably between about 10 and 40 1 / s.

36. The extractive gas analyzer system as claimed in claim 34 or claim 35, wherein at least one of said line cleansing gas and said probe cleansing gas comprises an inert gas such as N2 or air.

37. The extractive gas analyzer system as claimed in any one of claims 34 to 36, wherein the preselected volume of probe cleansing gas is selected at between about 51 and 301, and the probe valve is operable to supply the volume of probe cleansing gas at a velocity selected to effect shockwave cleansing of said probe interior at a release flow rate of between about 1 and 300 1 / s, preferably about 5 and 10 1 / s, and most preferably between about 10 and 50 1 / s.

38. A gas analyzer system comprising, a gas analyzer for analyzing one or more constituents in an industrial furnace off- gas stream, the gas analyzer including an analyzer component selected from the group consisting of a gas extraction port, an optical emitter and an optical receptor, a longitudinally elongated mounting or shielding tube, and a high velocity gas blow system for effecting shockwave cleansing of said tube and / or analyzer component, the tube extending from a proximal end portion to an open distal end and comprising a tubular outer sidewall configured for positioning in the industrial furnace off-gas stream extending from said proximal end portion to said distal end and defining a hollow interior, and said analyzer component being substantially housed within the hollow interior, and preferably being spaced towards the distal end,the high velocity gas blow system including a high pressure gas source configured to create a gas burst shockwave from the sudden release of a preselected volume of analyzer cleansing gas at pressure selected at between about 3BAR and 10BAR, and preferably about 7 to 8BAR, the high pressure gas source being in selective fluidic communication with the tube interior via an inlet port spaced towards, and preferably adjacent said proximal end portion, and a valve assembly selectively actuable to effect flow of the volume of analyzer cleansing gas from said inlet port and into said hollow interior as a reverse gas burst flow.

39. The gas analyzer system as claimed in 38, wherein the valve assembly comprises a quick release valve configured to effect the flow of the analyzer cleansing gas at or towards said analyzer component and along said hollow interior as a shockwave.

40. The gas analyzer system as claimed in claim 38 or claim 39, wherein the analyzer component comprises a gas sampling tube, and the tube comprises an extractive gas sampling probe.41 . The gas analyzer system as claimed in claim 38 or claim 39, wherein the gas analyzer comprises a TDLAS gas analyzer, and the analyzer component is selected from the group consisting of a laser beam emitter, a laser beam receptor and an optic window for a laser beam emitter or a laser beam receptor.

42. The gas analyzer system as claimed in claim 38 or claim 39, wherein the gas analyzer comprises an IR analyzer or a FTIR analyzer, and the analyzer component is selected from the group consisting of an infrared sensor and an optic window for an infrared sensor.

43. An extractive gas analyzer system for analyzing a furnace off-gas flowing in a furnace flue duct, and preferably an EAF or BOF furnace duct, the analyzer system comprising, a gas sampling probe, the probe being elongated along a longitudinal axis and extending from an open distal end disposed in the furnace flue duct to a proximal end spaced outwardly therefrom, the probe comprising,an outer sidewall extending about said axis from the open distal end towards the proximal end and defining a hollow probe interior, and an elongated sampling tube disposed at least in part in said probe interior and extending generally along said axis from an inlet end open to said interior and disposed towards said open distal end, to an outlet end disposed towards the proximal end, a gas supply line fluidically communicating the outlet end with a gas analyzer assembly spaced a distance from the furnace flue duct, the gas analyzer assembly being operable to draw said furnace off-gas from the flue duct into said sampling tube and along said supply line in a first flow direction for analysis; a line cleansing assembly selectively operable to suddenly release a preselected volume of pressurized line cleansing gas in a fashion that creates a shockwave in said gas supply line as a line cleansing method travelling in a direction opposite to said first flow direction, and wherein the preselected stored volume of pressured line cleansing gas is maintained in a tank of between 2 and 40 liters, preferably 5 and 35 liters, most preferably about 5 and 30 liters, and has a pressure selected at between about 3BAR and 10BAR, preferably between about 7 to 10BAR; and / or a probe cleansing assembly selectively operable to introduce a shockwave created by a sudden release preselected volume of pressurized probe cleansing gas into said probe interior as a probe cleansing shockwave method travelling in a direction outwardly from the open distal end, wherein the preselected volume of probe cleansing gas is maintained in a suitably sized tank between about 5 liters and 40 liters at a pressure selected between about 3 BAR and 10BAR, preferably between about 7 and 10BAR; and a controller for controlling the line cleansing assembly and / or probe cleansing assembly to initiate a shockwave front by triggering the sudden release of said high pressure gas into the line and / or probe to remove built up material.

44. An extractive gas analyzer system for analyzing a furnace off-gas flowing in a furnace flue duct, and preferably an EAF or BOF steelmaking furnace flue duct, the analyzer system comprising, a gas sampling probe, the probe being elongated along a longitudinal axis and extending from an open distal end disposed in the furnace flue duct to a proximal end spaced outwardly therefrom, the probe comprising, an outer sidewall extending about said axis from the open distal end towards the proximal end and defining a hollow probe interior, and an elongated sampling tube disposed at least in part in said probe interior and extending generally along said axis from an inlet end open to said interior and disposed towards said open distal end, to an outlet end disposed towards the proximal end, a gas supply line fluidically communicating the outlet end with a gas analyzer assembly spaced a distance from the furnace flue duct, the gas analyzer assembly being operable to draw said furnace off-gas from the flue duct into said sampling tube and along said supply line in a first flow direction for analysis, a line cleansing assembly selectively operable to introduce a shockwave by the sudden release of a preselected stored volume of pressurized line cleansing gas into said gas supply line in a direction opposite said first flow direction, and wherein the preselected volume of pressured line cleansing gas is maintained in a tank selected at between about 2 liters and 40 liters, preferably about 5 liters and 30 liters, and has a pressure selected at between about 3BAR and 10BAR, preferably about 7 to 10BAR, a line valve selectively actuable to effect flow of the preselected volume of line cleansing gas into said gas supply line via an inlet port intermediate said outlet end and said gas analyzer, the inlet port being spaced 0.5 meters to about 10 meters and preferably about 5 meters to about 8 meters from said probe.

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