JP2003513272A - Continuous monitoring method of chemical species and temperature of high temperature process gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for monitoring and preferably controlling the performance of an industrial combustion space. A method and apparatus for monitoring and / or controlling a high temperature process using an oxidant including O ₂ and an organic fuel using a tunable diode laser. Real-time monitoring of important chemical species (O ₂ , CO, H ₂ O, etc.) to measure global or local chemical species, gas temperatures, particle concentrations, and air intake levels into the process Can be. Coupling the measured information with the control system provides a means to optimize and control the process.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of combustion. In particular, the invention relates to continuous monitoring of the concentrations of reactants, intermediates, or products from or in high temperature combustion processes. It is also possible to obtain measured values of the process gas temperature, the particle concentration level, and the air suction speed.

[0002]

[Prior art]

Many measurement methods can be selected for monitoring gas composition in industrial combustion processes operating at high temperatures (T> 500 ° C.). In particular, diagnostic measurement is effective for the analysis of important combustion chemical species (O ₂ , CO ₂ , CO, NO _x, etc.), and energy efficiency and product quality can be improved by optimizing and controlling the process using measurement information. Is improved and pollutants are minimized. However, high temperatures and high particle concentrations are typically found in industrial processes, limiting available monitoring methods to extractive sampling techniques. In special cases, as described below,
In situ techniques can also be used, but for limited operating conditions and a particular set of chemical species.

Conventional extraction sampling methods for gas composition analysis are performed using a heat resistant probe (eg, water cooled), a moisture removal system, a particle filter, and a wicking pump (withdrawing the sample from the process). .. The assembly of these components in front of the analyzer ensures cooling of the sample and removal of water and particulate matter from the sample. Many factory environments are not suitable for sensitive measurements, so the sampling line from the process to the analyzer can be tens to hundreds of feet long. The use of long sampling lines introduces a delay, which can be tens to hundreds of seconds before reaching the analyzer. The analytical measurement method is selected depending on the target chemical species. For example, paramagnetic resonance techniques or electrochemical cells are often used to monitor O ₂ concentration in a process or flue. A non-dispersive infrared detector may be used to monitor CO, CO ₂ , and NO. All of these commercially available analyzers exhibit a characteristic response time, which also adds to the measurement delay.

[0004]   Other instruments that can be used with the extraction sampling system include gas cylinders.
Romanograph (GC), mass spectrometer (MS), or GC / MS pair
There is a combination. The GC instrument contains many chemical species (O ₂ , N₂, CO₂, CO, H, etc.) can be monitored. But this
Since the instrument samples gas in batch mode, it has a slow response time and GC
It takes about 30 seconds to a few minutes depending on the production conditions. Discontinuous sampling and instrument response
Slow delays prevent the use of learned information in process control loops
Especially in the case of processes with dynamic behavior. Using MS equipment
Then, continuous gas sampling can be performed with a short response time <1 second.
However, the resulting mass spectrum is difficult to interpret. The reason is the same
This is because fragments of ionized molecules having high molecular weights overlap. In addition, MS equipment
Must be operated in vacuum. Change in sampling flow rate (for example, blockage,
(Or due to pressure fluctuations in the process itself), the response of the detector changes, resulting in incorrect measurement.
There is a difference.

In-situ zirconium oxide (ZrO ₂ ) probe was used in the late 1960s NA
Developed by SA and used for O ₂ monitoring in many industrial applications. This sensor uses a sealed ZrO ₂ tube which, when heated, becomes an electrolyte conductor due to the mobility of O ₂ ions, with a minimum operating temperature of ˜600 ° C. for permeation of ions. is necessary. The sensor is capable of operating at moderate to very high temperatures> 1600 ° C. and response times are reported to be on the order of seconds. The device works well in relatively clean environments (low levels of excess O ₂ present (a few percent)), for example in steel slab reheat furnaces. However, in a high particle process or reducing environment, clogging of the probe surface causes measurement degradation. Also, in processes where thermal cycling can be large (experienced in a batch process), thermal shock to the ceramic probe can result in permanent damage.

In order to overcome the lag time issues associated with extractive sampling techniques, and the limited flexibility of ZrO ₂ probes, optical measurement techniques, ie, by absorption, for making in-situ measurements on combustion processes. Means are brought. Since the optical measurements are non-intrusive, the measurements can be performed even in the most harsh environments, including high particle density atmospheres (which can be reducing or oxidizing). Temperature limits are not important. Because the measurement is optical and is done in-situ. Also, when performing optical measurements in corrosive atmospheres (acidic or basic), their handling is not accompanied by the difficulties typically experienced with extractive sampling.

[0007]   Products, reactants, or to monitor and control the combustion process
Intermediate products can be detected. For hydrocarbon fuels, the main source of complete combustion
The product is N₂(Introduced by fuel or oxidant), CO₂, And H₂O
Consists of O₂CO and H when operating under lean conditions₂Also exists. O ₂ In the rich state, excess O₂Are observed in the process exhaust gas. Therefore
, CO and O monitoring₂Is the stoichiometry of the local or global process
Is an important chemical species when defining the theory.

A means for performing in-situ measurements in harsh process environments by means of optical measurement techniques, avoiding problems such as long lag times, thermal cycles, and atmospheric effects (reducing or oxidizing). Is given. Many optical techniques using simultaneous monitoring of O ₂ and CO to monitor and control combustion space stoichiometry use lasers such as Raman, REMPI (Resonant Multiphoton Ionization), or absorption in the UV region. Can be done by. However, these techniques have, until now, been limited to well-controlled environments because of the drawbacks required complex optics. As a result of advances in solid-state diode lasers, this device provides the simplicity needed to make absorption measurements in harsh factory environments. A solid-state laser is a small, powerful device that provides a spectrally pure narrow linewidth tunable radiation source (typically 1 MHz) with wavelength accessibility.
The length accessibility) is 600 nm to 25 μm.

In particular, diode lasers operating in the near infrared spectral range (600-2000 nm) provide tunable radiation sources consisting of devices operating near room temperature and compatible with standard optical fiber components. Standard here refers to the usual materials used in the telecommunications industry, for example silica. Diode lasers operating at longer wavelengths (greater than 2.0 mm) require special cooling. Mid-infrared diode lasers (2.5-25 μm) require cryogenic cooling and are not easy to combine with fiber optics. Therefore, this device is unwieldy for industrial applications. On the other hand, the transitions observed in the near infrared do not originate in the fundamental band, but rather in the overtone or coupling band system. Therefore, the observed signal is small in order compared to the mid-infrared laser that examines the fundamental band. Nevertheless, many publications have been published demonstrating sensitive detection (ppm levels) of many gas species, including those important in combustion. The combination of room temperature operation and compatibility with commercially available fiber optic systems make near infrared diode lasers the preferred choice for industrial monitoring applications. Its compatibility with fiber optics provides a means for transporting laser radiation to the measurement point of the process, and a means for networking multiple sensors together.

[0010]

[Problems to be Solved by the Invention]

The main object of the present invention is to provide a method for monitoring, and preferably controlling, the performance of an industrial combustion space. Performance herein may refer to overall stoichiometry, or stoichiometry of a particular zone of the process, gas temperature, particle density, or air intake level. One or more performance criteria can be monitored simultaneously.

[0011]

[Means for Solving the Problems]

The methods provided herein allow in-situ real-time measurements for critical combustion process parameters such as product, intermediate, or reactant species concentration, gas temperature, and particle load density. , Provides a means of performing absorption measurements using a diode laser source. This information can then be related to overall or specific zone process stoichiometry, air uptake rates, particle density levels, and gas temperatures. The measurements can be used in process control strategies to improve energy efficiency, product quality, and pollutant reduction. Since the method uses line of sight optical measurements, no gas extraction is required. As a result, system costs and associated maintenance issues due to probe clogging are reduced. The feature of this method is the short-time response, which enables real-time monitoring of the combustion atmosphere. Further, the effects of thermal shock or extreme changes in the combustion atmosphere (eg, highly reducing or oxidizing) are not harmful to the sensor. The proposed method of the present invention also exhibits further advantages by monitoring the actual gas temperature as well as particle density and air intake. All such information can be obtained at one line of sight location on the process. Also, multiple line-of-sight measurements can be performed by placing multiple diode laser systems at the point of the process location of interest.

The first aspect of the present invention is the overall or local chemistry of a process (preferably an oxy-fuel combustion process) operating in a lean state (ie in the presence of excess O ₂ ). It is a method of monitoring or controlling the stoichiometry. The method includes the following steps.

[0013] (a) a tunable diode initial collimated radiation beam emitted from a laser, relative to the step (O ₂ passing the process by firing along the line-of-sight path, the O ₂ B-X ( Selected rotation spectral lines (rotationa near the 0,0) band
l line) is preferably monitored. This corresponds to a wavelength around 763 nm. This wavelength is accessible using a commercially available AlGaAs diode laser which is optically matched to the fiber), (b) substantially opposite the launch position, the emitted radiation is collected and filtered out of the filter element. To a photodetector having a detector (the detector is preferably a silicon photodiode, a photomultiplier, or a similar photodetector sensitive to the O ₂ spectral region. The filter element is preferably narrow band. Reflector or transmission optics and / or dispersive element (used to suppress background radiation), (c) the initial beam observed when the laser is tuned to the resonant absorption spectral line of O _2. step of observing and processing the attenuation from (integrated area of the absorption spectral line is directly proportional to the O ₂ number density at a given temperature), (d) O ₂ number Based on the time, one or more of the following variables: process pressure, the fuel inlet flow, to produce an electrical signal for use in control of the oxidant inlet flow rate.

The electrical signal generated preferably allows the operator to be informed of the process operating conditions and to manually adjust the process by adjusting the oxidant, fuel, or process pressure or any combination of these three process variables. To
One preferred method is to use electrical signals to control the operation of one or more actuators to allow manipulation of one or more process variables. For example, if the process is a furnace, the flue area may be reduced to increase the furnace pressure. As a result, air ingress is reduced and the measured concentration of O ₂ is reduced. Instead,
The oxidant input flow rate (preferably containing air, oxygen-enriched air, or oxygen) can be adjusted to achieve the desired amount for the process. Similarly, the input fuel flow rate can be adjusted. However, this also affects the energy input to the process.

A second aspect of the invention is a process that operates in a fuel rich state (ie in the presence of excess CO) (a process that creates a reducing atmosphere of CO) (preferably oxygen-
Method of monitoring or controlling the overall or local stoichiometry of the fuel combustion process). The method includes the following steps.

(A) Launching an initial collimated radiation beam emitted from a tunable diode laser along a line-of-sight path to pass through the process (for CO, CO overtone band near 1.56 μm) It is preferred to use selected rotating spectral lines from S., which wavelengths are accessible using a commercially available InGaAsP / InP diode laser that can be optically coupled to the fiber), (b) launch position and On the opposite side of the filter, the emitted radiation is collected and transported to a photodetector having a filter element and sensitive to the CO spectral region, which detector is preferably an InGaAs photodiode, photomultiplier tube, or CO A similar photodetector sensitive in the spectral domain, the filter element preferably being a narrow band reflector. Or transmission optics and / or dispersive elements (used to suppress background radiation from hot walls and / or particles), (c) optical signal tuned the laser to the CO resonant absorption line. A step of observing and processing the amount of attenuation from the initial beam that is sometimes observed (the integrated area of the absorption spectrum line divided by the spectrum line intensity and the path length is C at a predetermined temperature).
Directly proportional to the O number density), and (d) generating an electrical signal for use in controlling one or more of the following variables based on the CO number density: process pressure, fuel inlet flow rate, oxidant inlet flow rate. .

The electrical signals generated preferably inform the operator of the operating state of the process and allow manual adjustment of the process by adjusting the oxidant, fuel, or process pressure or any combination of these three process variables. to enable. One preferred method is to use electrical signals to control the operation of one or more actuators to allow manipulation of one or more process variables. For example, if the process is a furnace, the flue damper area may be increased to reduce the furnace pressure. As a result, the ingress of air increases and combustion with air reduces the measured CO concentration. Alternatively, the oxidant input flow rate (preferably containing air, oxygen-enriched air, or oxygen) can be adjusted to achieve the desired CO concentration for the process. Similarly, the input fuel flow rate can be adjusted.

A third and preferred aspect of the present invention is a method of monitoring both CO and O ₂ number densities simultaneously or nearly simultaneously at a particular location on a process (preferably an oxy-fuel combustion process). is there. The preferred method is 10 for CO and O _2.
It is compatible with a range of process operating conditions that vary from 0% to 0.01%. The method includes the following steps.

(A) launching a plurality of parallel radiation beams emitted from a plurality of tunable diode lasers along a line-of-sight path to pass through the process (parallel beams have a plurality of wavelengths, eg 763 nm; And 1.5 μm radiation is included for O ₂ and CO monitoring respectively), and (b) launching multiple tunable beams simultaneously by spatially introducing the radiation through a fiber optic network (instead of , Multiple input beams are time-split, ie multiple beams are introduced at approximately the same time by tuning the lasers at different times), (c) Multiple frequencies are detected with dispersive elements and / or narrow band filters. Separating by distinguishing different wavelengths using a combination with a container and sending at the same time (
In the case of time division, by demodulating the input signal using a single detector,
(All wavelengths tuned can be resolved), (d) Optical signals are processed by observing the amount of attenuation observed when multiple signals are tuned to the resonance absorption spectral lines of a particular chemical species. (The integrated area of the absorption spectrum line is directly proportional to the number density at a given temperature), (e) based on the O ₂ number density, one or more of the following variables: process pressure, fuel inlet flow rate, oxidation Generating an electrical signal for use in controlling the agent inlet flow rate.

A fourth aspect of the invention is a method of monitoring the temperature of the gas phase of a process, preferably an oxy-fuel combustion process. The method includes the following steps.

(A) launching an initial collimated beam of radiation emitted from a tunable diode laser along a line-of-sight path to pass through a combustion process; (b) directing the diode laser of a selected species. Step of tuning to more than one rotating spectral line (temperature can be monitored using CO and / or O ₂ but preferred species is H ₂ O or other possible detectable process gas such as HCl). Regardless of which species is selected, it is preferred that the dependence on process stoichiometry be minimal: near infrared monitoring of H ₂ O (many absorption transitions 1.4, 1.5, and Existing in the 2.0 μm spectral region, which are accessible by near-infrared diode lasers) and are supplied with hydrocarbon fuel When performed on a combustion process, both CO and O ₂ concentrations are strongly dependent on process operating conditions, so no detectable species of either species are observed at all (ie, the concentration is too low to allow temperature measurements. For this reason, and also because H ₂ O is present in the majority of the combustion process, oxy-fuel combustion processes and other processes where the presence of H ₂ O is known to exist. H ₂ O is an ideal candidate for temperature monitoring.

(C) on the side opposite to the launch position, collecting the emitted radiation and transporting it to a photodetector having a filter element (sensitive to the wavelength of interest), which filter element is preferably , Narrowband reflectors or transmission optics and / or dispersive elements (used to suppress background radiation from hot walls and / or particles)
(D) the step of processing the optical signal by observing the amount of attenuation from the initial beam observed when the laser is tuned to two or more resonant absorption spectral lines (temperature is calculated using the formula Ask for.

[0023]

[Equation 3] Here, R is the ratio of the integrated absorption of each transition at an unknown temperature T. The parameters that make up the right side of the equation are all known except T. (S ₁ / S ₂ ) _{T 0} is a ratio of spectral line intensity values at a certain reference temperature T ₀ , ΔE is energy separation of an absorption state, h is Planck's constant, k is Boltzmann's constant, and c is speed of light. ) Based on the temperature of the gas phase, one or more of the following variables: process pressure,
Generating an electrical signal for use in adjusting fuel inlet flow rate, oxidant inlet flow rate.

The measurement of the gas phase temperature provides additional information, preferably used in the mass and energy balance of the process, and also in the spectral line intensities (used to determine number density from absorption measurements, useful in unit conversion). , Which is useful in process optimization).

For unit conversion, temperature is used to convert the number density values obtained from absorption measurements into industrially more acceptable percent concentration values (usually used in industrial plant environments). Process optimization is preferably performed on temperature measurements at defined process locations. For example, one purpose of a reheat furnace is to achieve a uniform billet temperature and hold the temperature for a predetermined time. Measuring the temperature of the gas phase near the billet surface provides feedback information about temperature levels and stability and provides a means to control unwanted temperatures or temperature fluctuations.

A fifth aspect of the invention is a method of monitoring particle concentration levels in a monitored gas phase region of a process. The method includes the following steps.

(A) launching an initial collimated radiation beam emitted from a tunable diode laser along a line-of-sight path to pass the gas phase; (b) delivering on the side opposite to the launch position. Collected radiation and transport it to a photodetector with a filter element (which is sensitive to the wavelength of interest), where the filter element is a narrowband reflector or transmission optics and / or a dispersive element (of background radiation). (Can be used for suppression))), (c) tune the laser offset from any of the resonant absorbing species and monitor the attenuated radiation detected, (d) the optical signal to detect all resonances of the laser. The process of observing and processing the amount of attenuation from the initial beam that is observed when tuned by shifting from the absorption spectrum line (observed attenuation is the line of sight The particle density along the path is related by the following equation: (I / I ₀ ) = exp (−a _ext l) where I ₀ is the beam initial irradiance and I is the beam distance l The measured irradiance after propagating through the process.If the absorptance a _ext is known in the presence of particles, the measured attenuation can be related to the particle number density), (e) particles Generating an electrical signal based on number density (the electrical signal is preferably used to adjust one or more of the following variables: process pressure, fuel inlet flow rate, oxidant inlet flow rate, and burner momentum ( It is preferable to change the momentum) and position adjustment by feeding back the effect of these adjustments on particle suction in real time.) Sixth aspect of a method of monitoring the air suction rate to the combustion process. The method includes the following steps.

(A) Concentrations of major combustion product species, such as CO ₂ or H ₂ O, are emitted along a line-of-site path with an initial collimated beam of radiation emitted from a tunable diode laser to drive the combustion process. Passing through and measuring, (b) collecting emitted radiation on the side opposite to the launch position and transporting it to a photodetector with a filter element (sensitive to the wavelength of interest) ( The filter element may be a narrow band reflector or transmission optics and / or a dispersive element (used to suppress background radiation from hot walls and / or particles))), (c) the optical signal to be resonantly absorbed by the laser. The process of observing and processing the amount of attenuation observed when tuned to the spectral line (the integrated area of the absorption spectral line and the spectral line intensity and path Is directly proportional to the number density at a given temperature), (d) the air intake rate into the process using the ambient air composition along with the fuel and oxidant inlet and flow rates, and for complete combustion. Estimating using the difference between the theoretical value and the measured concentration of the chemical species, (e) adjusting one or more of the following variables based on the air intake rate: process pressure, fuel inlet flow rate, oxidant inlet flow rate. Generating an electrical signal for use in.

A seventh aspect of the present invention is an indirect means of monitoring H ₂ (no infrared absorption transitions) and / or combustible hydrocarbons in the gas phase at high temperatures> 1000 ° C. This means includes the following steps.

(A) The H ₂ O concentration is emitted by launching an initial collimated beam of radiation emitted from a tunable diode laser along a line-of-sight path through a gas phase, preferably the flue gas of the combustion process. Te, a step of measuring in the spectral region H ₂ O absorption transition is observed, (b) at the opposite side to the firing position, to recover the sent radiation process (filter transporting a photodetector having a filter element The element is preferably a narrow band reflector,
A narrow band filter and / or a dispersive element (used to suppress background radiation))), (c) the optical signal initially observed when the laser is tuned to the resonant absorption spectral line of H ₂ O. A step of observing and processing the amount of attenuation from the beam (the integrated area of the absorption spectral line divided by the spectral line intensity and the path length is directly proportional to the H ₂ O number density at a given temperature), (d) The step of using the second measuring point in the gas phase region or in the bypassed gas stream (H ₂ O is measured as described above, but here O ₂ is introduced and mixed with the heating gas. O ₂ gas reacts with any unburned H ₂ and / or hydrocarbons that may be present to form H ₂ O as a product), (e) H ₂ O downstream of the O ₂ gas inlet and upstream. by measuring the difference between the side H ₂ O, the gas phase of the A step of calculating back the amount of ₂ and / or unburnt hydrocarbons, (f) based on the amount of unburned H ₂ and / or hydrocarbons, to produce an electrical signal (a, preferably this signal, one or more The following variables: used to control fuel inlet flow and / or oxidant inlet flow, and process pressure).

[0031] If the O ₂ is introduced into the gas stream, the O ₂ content can vary from air-pure O _2. However, O ₂ purity> 90% is preferred in order to ensure complete reaction of the gas and to minimize the effects of dilution. The same strategy can also be applied to CO monitoring. In this case, CO reacts with the introduced O ₂ in hot gas, for example combustion flue gas, to form CO ₂ . As a result, CO ₂ can be monitored in the 1.5 μm spectral region using a near infrared laser. By comparing the CO ₂ observed before the introduction of O ₂ with the CO ₂ observed after the introduction of O ₂ ,
An indirect means of measuring CO is obtained.

A further aspect of the method is a means for monitoring contaminant X, where X is a contaminant of particular interest to the process. For example, X can be NO or SO in the process flue exhaust or at a particular location in the process. This monitoring method includes the following steps.

(A) Launching an initial collimated beam of radiation emitted from a tunable diode laser along a line-of-sight path to pass through the combustion products of the combustion process (a preferred method when monitoring species X). Consists of monitoring one of the absorption transitions in the near infrared with no interfering background species (such as H ₂ O)), (b) the emitted radiation on the side opposite the launch position. Collecting and transporting to a detector having a filter element (the detector is preferably a silicon photodiode,
A photomultiplier tube, or similar photodetector sensitive to the spectral region of species X. The filter element may be a narrow band reflector or transmission optics and / or a dispersive element (used to suppress background radiation), (c) an optical signal that tunes the laser to the resonant absorption spectral line of species X. A process of observing and processing the amount of attenuation from the initial beam observed when (the integrated area of the absorption spectrum line is directly proportional to the number density at a given temperature), (d) based on the number density of the chemical species X And generating an electrical signal. The electrical signal is
It may be useful in controlling one or more of the following variables: process pressure, fuel inlet flow rate, oxidant inlet flow rate.

By including additional combustion species, such as NO and / or SO, with the main set of monitoring species, ie O ₂ , CO, H ₂ O, the exhaust gas and / or zones of the combustion process are fully enriched. A means of characterizing is provided. The wide wavelength range covered by diode lasers limits the detection of chemical species.
It depends on the physical process of the absorption process. For example, some chemical species are not infrared active (such as N ₂ ). On the other hand, other infrared-active species have limited applications. This is because the absorption transition is weak and / or there is interference by other species in the measurement volume.

The generality of the invention provides a unique method for monitoring the operating conditions of high temperature, large scale industrial processes. The short response time provides a means to monitor process conditions in real-time mode, allows confirmation of process changes (eg global or local stoichiometry), and uses adjustments to correct and tune processes. The desired operating state can be achieved. These and other aspects of the invention will be apparent upon consideration of the following description and appended claims.

[0036]   The drawings are not to scale and are only typical of actual embodiments.

[0037]

DETAILED DESCRIPTION OF THE INVENTION

The method of in situ, short response time and high precision monitoring of key gas phase species provides a means to regulate many industrial processes to maintain optimal performance. Performance here refers to estimates of global or local stoichiometry, gas temperature, particle density, and air intake. Measuring and controlling these quantities provides a means to control product quality, reduce pollutants, and improve energy efficiency.

Implementing the preferred monitoring method for the combustion process involves the following basic elements (shown in FIG. 1). Single or multiple diode laser 1
Is used in this embodiment. For O ₂ monitoring, a diode laser model 760DFB (sold by Sarnoff, Princeton, NJ) is suitable. Each diode laser has a current controller 2 and a temperature controller 3 for stability and wavelength tuning (eg Melles Griot, Carlsbad,
Model 56DLD403), sold by the State of California. The output of diode laser 1 is optically coupled to the fiber (according to model 22-10676040-4687, Gould Electronic, Millesville, MD) and transported to coupler 4. In the coupler 4, the input energy is split in half. If multiple lasers are used, the splitter will be nx2. Where n is the number of inputs with two outputs. The output of the coupler is transported by a single mode fiber 5 (OZ Optics, Ontario, Canada). This is a core with FC / APC connector / collimator ends and can be several hundred meters long. Therefore, place sensitive lasers and associated electronics in a safe, well-controlled environment to
(Typically found near industrial combustion processes).
The beam launch module 6 is placed at a process target monitoring location 8 using a water or gas cooled pipe 16. After the beam exits the fiber optics 5, the shaping and collimating optics 7 (eg, OZ Opt
ics is coated with anti-reflective coating and has a 2 mm waist at 1 mm position). Here, the beam is shaped to the desired diameter and divergence. In industrial processes where particulate matter is present, beam diameters typically range from 1 to 9 centimeters (c
m) is preferred. Increasing the beam diameter produces a spatial averaging effect, which improves the signal-to-noise ratio for flows containing particles and reduces angular dispersion. As a result, beam steering due to the temperature gradient is reduced. The beam 9 propagates through the cooled pipe 16 on the launch side and then across the process is received by a detector module 11 (located on the side opposite the beam launch module 6). Both the beam launch module 6 and the detector module 11 are purged by the gas 15. Any gas can be used as long as it does not contain the gas species being monitored. For example, N ₂ or air could be used
Only when performing CO monitoring. Even the process gas itself can be used, as long as the process gas is clean (free of particulate matter), dry (dehydrated) and does not contain any absorbing gas species. is there. Also, the process gas must be cooled to an acceptable temperature (depending on the components used in the module). The detector module 11 is
After receiving the beam, it sends it to the detector 10. Detector 10 includes one or more of the following elements: narrow band filter, dispersive element, or narrow band reflector to select laser emission for photodetectors (eg, EG & G Optoelectronic, Salem, Model UV245BQ, Salem, Mass.). To send. The filter is also used to suppress small background emissions from high temperature processes. The output of the photodetector 12 is sent to a balanced radiometric detector (BRD) 13 with a beam splitting portion 14 from the coupler 4 (used as a reference). The BRD 14 is a noise canceling electronic circuit. The output from the BRD shows the logarithmic ratio of the measured intensity from the detector 12 and the reference intensity 14. The output from the reference numeral 14 is processed by the computer 17 to obtain the measured number density of the chemical species.

The apparatus shown in FIG. 1 is an example of a preferred apparatus for making absorption measurements on industrial combustion processes. After the beam is generated by the diode laser,
The absorbance is measured as it propagates across the gas region of the process. The difference between the known approach and method and the device of the invention is in the way the absorbance signal is measured. Diode lasers are inherently "noisy" devices, which usually have accessible vibrational overtones in the near infrared region and weak absorbance of the bandpass transition. Therefore, it is necessary to reduce noise. Direct absorption monitoring can be performed under the following conditions. Strong absorption transitions, high concentrations of monitored species, or sufficiently long path lengths.
However, for combustion applications, a large dynamic range is required and short path lengths are required (because of beam steering and particulate matter in the gas). Therefore, direct absorption has limited applications, and noise suppression techniques need to be implemented.

Many applications of diode laser monitoring have been demonstrated, these using the technique of modulating a diode laser at high frequency (f) and detecting the absorbance by a lock-in amplifier at 2f (second derivative). There is. This method is generally called frequency modulation (FM spectroscopy), and detects the second derivative of the resonance frequency spectrum line shape. This technique can be used, but the preferred method is Physical Sci.
It is advertised by ences. This method uses balanced radiation detection electronics (first developed by Hobbs et al., US Pat. No. 5,134,276). See the following references: PCB Hobbs, `` Shot noise-limited optica
l measurements at baseband with noisy lasers "," Lasers Noise ", 1376,
Society of Photo-Optical Instrumentation Engineers, pp.216-221 (1990). This document is incorporated herein by reference. This technique has the advantage of measuring the true spectral lineshape and does not require a high frequency generator and lock-in amplifier. A discussion of high frequency generators can be made by reviewing the following documents: KL Haller and PCB Hobbs "Double Beam Laser Absorptio
n Spectroscopy: Shot Noise-Limited Performance at Baseband with a Novel E
lectronic Noise Canceller "," Optical Methods for Ultrasensitive Detect "
ion and Analysis: Techniques and Applications, '' 1435, Society of Photo-O
ptical Instrumentation Engineers, p.298 (1991). These documents are incorporated herein by reference.

The laser is tuned to a narrow wavelength range that includes the resonant absorption transition of the target species so that the absorption of the target species is affected by window fouling, the presence of particles along the beam path, and other molecular species. Keep away from. Using multiple wavelength regions from multiple lasers and / or a single laser (obtained tuned broadly), as shown in the following references for performance, Upschulte et al., "Measurement"
of CO, CO ₂ , OH and H ₂ O in Room Temperature and Combustion Gases By Use
of a Broadly Current-Tuned Multi-Section Diode Laser "(Applied Optics 3
8 (9), 1999), ie near-simultaneous detection of multiple target species. An excellent time response is obtained with a continuous bandwidth of 100 Hz (measurement time 0.01 s), and a bandwidth of 1000 Hz can be achieved in special cases. The short time response allows for monitoring of dynamic process conditions, and even small changes such as CO bursts or variations in air ingress, which can affect overall process performance, can be resolved.

[0042]

【Example】

In the examples below, real-time monitoring of O ₂ was performed using the configuration shown in FIG. This configuration was installed in a natural gas oxyfueled pilot furnace operating at 1.5 MMBtu / hr. To monitor O ₂ , AlG
aAs diode lasers, P ₂ of the weak transitions forbidden electronic system for O ₂ (25
) It was tuned to the rotating spectral line (near 763 nm). In this case, the process gas temperature was 1363 K and the excess O ₂ concentration was 5.2%. Tuning the laser to the transition provides a means to obtain the full spectral lineshape as shown in FIG. Also shown in FIG. 2 is the Voigt spectral lineshape function, and a good comparison is shown between the measured and theoretical spectral lineshapes. The concentration is determined using the Beer's law below.

[0043]     I = I₀exp [-S (T) g (ν) Nl] Where I₀Is the incident laser intensity, I is the distance l and has propagated through the process
Later measured laser intensity, S (T) is temperature-dependent absorption spectrum line intensity, g (n)
Is the frequency-dependent spectral line shape, and N is the number density of the absorber. log (I / I ₀ ) Is recorded directly from the BRD circuit used in the system shown in FIG.
I want you to understand. S (T) is a function of temperature, so we need to know about temperature
is there. If not, the absorption spectrum line is used as the temperature within the target range.
On the other hand, it is possible to select a relatively insensitive one. The number density uses the equation of state
Can be converted to concentration, but the signal is spread over the range of the absorption spectral line shape.
The integral can be obtained as follows.

[0044]

[Equation 4] Where S (T) is the spectral line intensity, l is the path length, I _v0 is the reference beam intensity, and I _v is the measured intensity after passing through the process.

[0045]   Figure 3 shows an example of real-time monitoring. This is O₂Measure changes in number density
It is a fixed one. Here, in order to dynamically change the stoichiometry, fuel (natural
Change of square wave (0.1Hz) in gas flow rate is 4m x 1m x 1m furnace smoke
For oxy-fuel combustion with an average burning rate of 1.5MMBtu / hr
And is implementing. The dynamics of combustion stoichiometry due to varying fuel flow rates
A change occurs and oscillates between the lean and rich fuel states. Similarly, 1.5
It is performed for CO using an InGaAs / InP diode laser near 6 μm.
The resulting measurement is shown in FIG. Here, the fuel flow rate is changed at a frequency of 0.5 Hz.
ing. The flue gas composition produced in this mode of operation also includes excess CO concentration and excess O 2₂concentration
And (during the fuel rich cycle and the fuel lean cycle, respectively). this
Due to the time-dependent measured number density, the diode laser absorption method
The unique ability to capture the periodic temporal behavior of processes has been demonstrated. Conventional, O ₂ The extraction and solid state analysis methods for CO and CO are as described above.
Moreover, we cannot resolve such time-dependent changes.

Real-time monitoring of dynamic process changes provides a means of coupling the sensor with the regulation system, which can be used for process optimization. For example, electric arc furnace (processing of secondary steel) or rotary kiln (process)
Secondary aluminum or iron melt) etc. operate in batch mode. First, scrap iron and / or raw materials are charged into the process and electrical and / or chemical energy is input to initiate melting. Large amounts of CO are produced in this type of process, which means energy loss and environmental hazards. In order to obtain an improvement in energy efficiency, the composition of the flue gas is monitored and an O ₂ containing gas (concentration range (20% -100)) is introduced. CO is oxidized by the excess O ₂ and heat energy is recovered. However, CO emissions from this process can be transient in nature. Applying conventional extractive sampling systems to these types of processes suffers from slow response times and maintenance problems (related to clogging due to high particle loading), as described above. Near-simultaneous real-time monitoring of CO and O ₂ using a diode laser system for processes exhibiting dynamic behavior and high particle loading,
The problems encountered with conventional exhaust gas analysis are avoided. By monitoring the concentration of key target species, a regulatory system using this information can optimize process energy utilization, product quality, and minimize pollutants.

An example showing diode laser monitoring for dynamic processes is shown in FIG. This is for an electric arc furnace (EAF). In this case, the sensor beam launch module and the detector module described above are located near the flue area and are at positions 1 or 2 in FIG. Position 1 is between the exhaust gas of the EAF furnace and the water cooled duct. At this location, air is drawn in and mixed with the flue gas.
Therefore, for monitoring at this position, the optical path length must be provided between the beam emitting module and the receiving module such that the inhalation of ambient air does not affect the measurement. In position 2, the sensor system has a process lid 14
Is attached to. Since the process operates in batch mode, the lid 14 is removed and the raw material 5 is loaded into the tank 3. Then, the lid 14 is returned together with the electrode 4. By performing the exhaust gas monitoring at position 1 or 2, the transmission signal 6 for CO, O ₂ , H ₂ O is sent to the processor 7, where the signal is converted into concentration. This information is then sent to a control system 8 (e.g., programmable logic controller (PLC)) from which signal 9 is sent to flow control valves 11 and 13. Based on the exhaust gas analysis, the control valve for the auxiliary burner 10 can be adjusted to increase or decrease the O ₂ flow rate. Similarly, the O ₂ flow rate can be adjusted on the O ₂ lance 12. Although shown in this example for EAF applications, any dynamic combustion process can be retrofitted with an integrated diode laser control system.

The introduction of the second monitoring position upstream of position 1 or 2 shown in FIG. 5 is carried out in the process or in the diverted flue gas stream. This thus provides a means of indirectly monitoring the H ₂ content in the gas. In the EAF example, in addition to CO (meaning energy loss in the exhaust gas), H ₂ can also be present in high concentrations. Introducing O ₂ into the high temperature process at the second location reacts with the H ₂ flue gas and any unburned hydrocarbons to produce H ₂ O as a product species.
O ₂ may be introduced into the surroundings or may be heated using a heat exchanger. The heat exchanger utilizes thermal energy from the flue itself or other means (such as a secondary burner or electrical). Of H ₂ O concentration by measuring at two different positions, can be attributed to changes in the H ₂ O content to the amount of H ₂ and / or unburnt hydrocarbons.

In dynamic processes such as EAF, rapid changes in exhaust gas composition may be experienced on a tenth of a second time scale. The response time of conventional industrial flow control valves can be the rate limiting step in this scheme. This is because adjustment of this valve can take many tenths of a second. A preferred system uses a regulation system and a solid state proportioning control valve (eg, as described and claimed in US Pat. No. 5,222,713) with a short response diode laser sensor. This document is incorporated herein by reference. In this case, a large volume of gas flow can be rapidly controlled, so that a short-time response diode laser sensor (delay limited to the residence time of the process) can be fully used. In this application example, the exhaust gas composition is measured by a diode laser. Based on the CO and O ₂ content in the exhaust gas, the controller changes the proportional valve width to the desired value and reduces or increases the O ₂ flow rate. The response of proportional valves is on the order of milliseconds and can be considered essentially instantaneous. This control valve can also be pulsed. As a result, process gas mixing is improved and residence times are further reduced. Further, the measurement position of the diode laser is preferably arranged at a position targeted for the process to further shorten the delay time. This is because measurement delay can still be a problem for high volume processes.

In the next set of examples, as an application example using the diode laser sensor method of the present invention, one having full monitoring performance (including T, CO, O ₂ , particle concentration, and air suction speed) will be described. To do. Each of these parameters provides important information about the process and can be used for optimization and control. For example, when controlling industrial processes using oxidant fluids composed of oxygen-enriched air or pure oxygen, the permissible range of controllability is greater than that of air. As shown in FIG. 6, for processes using pure O ₂ , a small change in oxidant inlet results in a large change in oxidant outlet. Excess O ₂ in the exhaust gas promotes NO _x formation. For O ₂ -enriched air, the sensitivity lies between the air curve of FIG. 6 and the pure O ₂ curve, with the slope increasing with increasing O ₂ content in the oxidant. The tolerance for excess O ₂ is process dependent and can affect the production process in terms of quality, capacity and thermal efficiency, as well as the environmental impact associated with NO _x formation.
The suction air to the process, not only the level of the oxidizing agent is increased, because the N is additionally introduced, causing an increase in energy loss and / or NO _x formation. Similarly, the presence of CO indicates a reducing atmosphere, which can affect process quality, production, and can be a safety concern (as CO is toxic and flammable).

The diode laser detection method of the present invention, which is the first embodiment presented, was applied to the glass melting tank 1 as shown in FIG. Raw materials are placed on the left side of the melt tank 1 and flow to the right side into a refining zone 2 from which they are allocated to the production of fibers or vessels. The exhaust pipe 3 of the furnace is arranged in the same region as the raw material inlet. The furnace is
O ₂ - can be operated with fuel or O ₂ enriched air fuel burners 4. A beam launch module 6 and a detector module 5 are provided at selected locations on the furnace 1. For illustration purposes, three monitoring locations are shown in Figure 7. In principle, N monitoring points can be chosen. The laser system 10 is located remotely from the process and sends the N selected wavelengths to the beam launch module 6 via the fiber optics 8. The beam 7 of N wavelengths is temporarily separated and propagates along the line-of-sight path, passing through the process and reaching the detector module 5. The resulting transmittance signal 9 is sent back to the laser system 10 so that the information is processed into physical quantities (eg temperature and concentration). The measurement results are sent to the monitoring system 12 of the furnace through the joint 13. Based on the measurement results, the monitoring system 12 sends a signal 11 to the appropriate flow control valve using a regulation algorithm. Regenerators or recuperators are also suitable for this monitoring and control method. Hybrid furnaces (heat storage or recuperation type with O ₂ lances and / or auxiliary burners) are also suitable for the method.

[0052]   As shown in Fig. 7, monitoring at three locations makes it possible to use different zones for different processes.
Information is obtained. At location A, the measurements are near the furnace exhaust pipe and ₂ Get general information about air, CO, air inhalation and particle carry-in
You can Further, the measurement area may be limited by adjusting the length of the path to be observed. Toi
This is because this monitoring technique is the sum of line-of-sight routes.
Control of path length extends the cooled pipe 14 (discussed in FIG. 1)
, Indicated by shortening the path. The shorter the path length, the higher the particles.
Preferred for loads. In case of high particle load, if the path distance is long,
Significant beam attenuation can occur due to the absorption. In zones B and C
The average stoichiometry and temperature observed in the area can be monitored. Also
Operating conditions Change the particle density, for example by changing the momentum of the burner.
It can be observed.

Performing the measurements in exhaust gas provides overall process stoichiometry monitoring by determining O ₂ and CO concentrations. The use of these measurements in combination with the air intake rate estimated from H ₂ O measurements provides a means for adjusting the oxidant input of the burner and the furnace pressure. The air intake also preferably informs the operator of a furnace leak due to possible refractory damage. The measurement of the level of particulate matter in the exhaust gas is performed synchronously with at least one laser off the absorption transition. Here, this information is preferably used as feedback regarding the placement of the burner in the glass tank, the momentum of the burner, the angle of the flame with respect to the glass bath. Changes in these parameters are known to affect volatilization, which causes higher levels of particulate matter (ref) in the flue exhaust. It can also inform furnace operators of potential problems (eg, flame impingement due to crown deflection or refractory damage near the burner exit) when any major or sudden changes occur at the particle level. it can. By measuring the temperature from at least two rotational spectra, it is possible to determine the spectral line intensity values needed to determine all the concentrations of the species to be measured. In this way, the measured values can be converted into percent readings to replace the number density, and the furnace operator can
More favorably accepted.

Also, as shown in FIG. 7, process monitoring can be performed at selected locations within the process. Since the measurement is optical, no disturbance is introduced into the process as is the case with sampling probe measurements. In this case, the measurements are made along the path length, so a summed average over the line-of-sight path is obtained. Therefore, high or low levels of O ₂ detected along the path
I do not know the spatial position of. Also, the observed absorption signal may be biased towards the hot or cold side, depending on the transition being monitored. The preferred method is to select absorption transitions that have a weak temperature dependence in a given process temperature range. Such an application allows local control of stoichiometry for specific zones of the process. The coupling of the sensor and flow control by a control loop provides a means to optimize the desired stoichiometry. In the case of glass, the color of the glass becomes unstable when the melting furnace is operated in a reducing atmosphere.

The basic principles already outlined in the application examples for glass melting tanks can likewise be applied to steel reheating furnaces. In this case, stoichiometry is an important control parameter to minimize the scale formed on the billet. here,
Preferred sensor locations can be determined so that the beam propagates near the billet surface to adjust O ₂ concentration and temperature uniformity. Although the process is different from glass melting, the method and coupling with the conditioning system is the same. However, the key parameters in optimizing and controlling the process can be different.

Other applications using the diode laser sensor method of the present invention can be found in the chemical industry for processes that can be highly corrosive. The non-invasive nature of the method of the present invention is ideal for application to such processes. In one such example, a sulfur recovery unit is used to recycle sulfur, which is used in the Plexiglas industry to produce MMA (methyl methacrylate). This process has been demonstrated to be improved by replacing some of the air with pure O ₂ . The use of pure O ₂ results in increased capacity, overall reduction of pollutants (SO _x and NO _x ), improved fuel efficiency and reduced CO ₂ emissions. In this case, the sensor is placed at the beginning of the process. The O ₂ inlet flow rate of the process is adjusted through a regulation system while monitoring O ₂ , CO, T in real time to minimize NO _x . Further, since organic compounds are present in the waste acid, it is necessary to burn it. Here, CO monitoring is used to ensure complete combustion of all organics entering the process by adjusting the oxidant inlet conditions by appropriate adjustment.

Variations on the monitoring method can be considered for industrial processes where the beam energy is highly attenuated due to the extremely high particle loading. The effect of particle concentration and path length is shown in FIG. At high particle concentrations and small diameter particles, the laser intensity attenuation can be completely absorbed. Short path lengths are the preferred solution, but in some cases short path lengths may not be sufficient. In such a case, the dilution method as shown in FIG. 9 can be used. Here, the dirty process gas is flowing in the duct 1 in the direction indicated by reference numeral 2. A part of the flow is diverted and put into the reference numeral 3, where the diluent gas 4 is used for mixing to reduce the particle density. The flow passes through the outer chamber 6 and then exits where it returns into the main process flow. A diode laser monitoring system 7 is provided in the outer chamber. The preferred diluent gas may be any gas that does not contain the target species monitored by the diode laser. To convert back to process gas concentration,
You must know the flow rate of the diluent gas. The amount of diluent gas may be high.
This is because the diode laser monitoring method has high sensitivity.

Although the present invention has been described above, it will be appreciated by those skilled in the art that many changes and modifications may be made to the above described embodiments without departing from the scope of the present invention.
tisan) is easily apparent.

[Brief description of drawings]

FIG. 1 shows a schematic block diagram illustrating a configuration for industrial monitoring and control.

FIG. 2 is a graph showing a comparison between measured O ₂ absorption and theoretical Vogtfit.

FIG. 3 is a graph showing changes in O ₂ number density measured in a dynamic combustion process with time.

FIG. 4 is a graph showing changes in CO number density measured in a dynamic combustion process with time.

FIG. 5 shows a schematic block diagram showing the conceptual application of the diode laser monitoring method in an electric arc furnace.

FIG. 6 is a graph showing the relationship between the excess oxidant introduced into the combustion process and the percent O ₂ observed in dry flue gas when increasing the O ₂ concentration in the oxidant.

FIG. 7 shows a schematic block diagram showing the conceptual application of the diode laser monitoring method in a glass melting furnace.

FIG. 8 is a graph showing the relationship with the observed transmittance through a medium containing particles of a particular size.

FIG. 9 shows a schematic block diagram illustrating a conceptual method for performing absorption measurements under high particle loading.

[Explanation of symbols]

  1 ... Diode laser   2… Current controller   3 ... Temperature controller   4 ... Coupler   5 ... Fiber optics   6 ... Beam launch module   7 ... Collimating optical system   8 ... Monitoring position   9 ... Beam   10 ... Detector   11 ... Detector module   12 ... Photodetector   13 ... Balanced radiation detector   14 ... Standard strength

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] February 4, 2002 (2002.2.4)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Equation 1] (Where R is (S _Θ / S _θ ) _{ω 0} , the integral absorption of each transition at an unknown temperature T,
This is a ratio of spectral line intensity values at a certain reference temperature T ₀ , ΔE is energy separation of absorption state, h is Planck's constant, k is Boltzmann's constant, c is speed of light), and (e) Based on one or more of the following variables: process pressure, fuel inlet flow rate,
Generating an electrical signal for use in adjusting the oxidant inlet flow rate.

[Equation 2] (Where R is (S _Θ / S _θ ) _{ω 0} , the integral absorption of each transition at an unknown temperature T,
This is a ratio of spectral line intensity values at a certain reference temperature T ₀ , ΔE is energy separation of absorption state, h is Planck's constant, k is Boltzmann's constant, c is speed of light), and (e) Based on one or more of the following variables of the oxy-fuel combustion process: generating an electrical signal for use in adjusting process pressure, fuel inlet flow rate, oxidant inlet flow rate.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Sharon, Olivier             60610, Illinois, United States             Basket, West Superior 1 (72) Inventor Sonnenflow, David M             Massachusetts, United States             01845 North and Bar, Village W             Yeah 1 (72) Inventor Mullhall, Philip A.             New Hampshire, United States             03873 Sundown, Phillips Wood             De Road 9 (72) Inventor Allen, Mark Gee             Massachusetts, United States             02116 Boston, No. 1, Applet             N Street 114 (72) Inventor Wetgen, Eric             California, United States             95051 Santa Clara, number 9201,             Pepper Tree Lane 900 F term (reference) 2G059 AA01 AA10 BB01 CC04 CC05                       CC09 EE01 EE11 GG01 GG09                       HH01 JJ03 JJ05 JJ06 JJ11                       JJ17 JJ22 KK01 MM05 NN01                       NN02                 2G066 AA01 AC01 AC14 BA11 CA11                       CA20

Claims (29)

[Claims] 1. A method for monitoring or controlling the global or local stoichiometry of a process operating in a lean state, comprising: (a) an initial collimated beam of radiation emitted from a tunable diode laser; and firing along the site path is through the process, with respect to O _2, can be accessed using the commercially available AlGaAs diode laser adapted optically to the fiber, the O ₂ corresponding to the wavelength of around 763 nm B- Monitoring selected rotational spectral lines near the X (0,0) band; (b) collecting the emitted radiation at a location substantially opposite the launch location and having a filter element O a step of transporting the optical detector sensitive to _second spectral region, observed when tuned to (c) an optical signal, a laser resonance spectrum lines of O ₂ Observing attenuation of the initial beam processing, integrated area of the absorption spectral line is a step that is directly proportional to the O ₂ number density at a given temperature, on the basis of the (d) O ₂ number density, one or more The following variables: process pressure, fuel inlet flow rate, generating an electrical signal for use in controlling oxidant inlet flow rate. 2. A generated electrical signal informs an operator of process operating conditions and allows manual adjustment of the process by adjusting oxidant, fuel, or process pressure or any combination of these three process variables. The method according to claim 1, wherein 3. The method of claim 2, wherein the electrical signal is used to control the operation of one or more actuators to enable manipulation of one or more process variables. 4. A method for monitoring or controlling the global or local stoichiometry of a process operating in a fuel rich condition, comprising: (a) initially collimating a beam of radiation emitted from a tunable diode laser; From the CO overtone band near 1.56 μm, which is launched along the observer path to pass through the process and is accessible to CO with a commercially available InGaAsP / InP diode laser that can be optically coupled to the fiber. And (b) collecting the emitted radiation at a location substantially opposite the launch location to provide a light having a filter element and sensitivity to the CO spectral region. Transport to detector, (c) observed optical signal when the laser is tuned to the resonance absorption line of CO Observing and processing the amount of attenuation from the initial beam, dividing the integrated area of the absorption spectrum line by the spectrum line intensity and the path length, a step directly proportional to the CO number density at a given temperature, and (d) CO Generating one or more of the following variables based on number density: process pressure, fuel inlet flow rate, oxidant inlet flow rate, and generating an electrical signal for use in controlling the same. 5. A generated electrical signal informs an operator of process operating conditions and allows manual adjustment of the process by adjusting oxidant, fuel, or process pressure or any combination of these three process variables. The method of claim 4, comprising: 6. The method of claim 5, wherein the electrical signal is used to control the operation of one or more actuators to enable manipulation of one or more process variables. 7. The method of claim 6 wherein the flue damper area is increased to reduce the process pressure to increase air ingress and combustion with air reduces the measured CO concentration. . 8. The method of claim 6, wherein the inlet flow rate of the oxidant, which may consist of air, oxygen-enriched air, or oxygen, can be adjusted to achieve the desired CO concentration for the process. 9. A method for monitoring the number densities of both CO and O ₂ simultaneously or substantially simultaneously at specific locations on the process, comprising: (a) a plurality of tunable diode lasers emitting a plurality of tunable diode lasers. A collimated beam of radiation is launched along a line-of-sight path to pass through the process, the collimated beam containing radiation at multiple wavelengths, eg, 763 nm and 1.5 μm, for O ₂ and CO monitoring, respectively. (B) launching multiple tunable beams simultaneously by spatially introducing radiation through a fiber optic network, or, alternatively, splitting the multiple input beams in time, ie tuning the lasers at different times. By introducing a plurality of beams substantially at the same time, and (c) using multiple frequencies as a dispersion element and / or a narrow band filter When the detectors are combined to separate different wavelengths for simultaneous transmission, and in the case of time division, a single detector is used to demodulate and tune the input signal. Resolving all wavelengths, and (d) processing the optical signal by observing the amount of attenuation observed when multiple signals are tuned to the resonance absorption spectral lines of a particular chemical species. The integrated area of is directly proportional to the number density at a given temperature and (e) one or more of the following variables based on the O ₂ number density: process pressure, fuel inlet flow rate, oxidant inlet flow rate control. Generating an electrical signal for use. 10. A method of monitoring the temperature of a gas phase of a process, comprising: (a) launching an initial collimated beam of radiation emitted from a tunable diode laser along a line of sight path. And (b) selecting the diode laser from a group consisting of CO, O ₂ , H ₂ O, or other detectable process gas that is not strongly dependent on process stoichiometry, such as HCl. (C) collecting the emitted radiation at a location substantially opposite the launch location and having a sensitivity in the spectral region of interest having a filter element; Transporting to a photodetector (which is sensitive to the wavelength of interest) to produce an optical signal; Observing and processing the attenuation from the initial beam observed when tuned to vector lines, the following equations temperature, Equation 1] (Where R is the ratio of integrated absorption of each transition at an unknown temperature T, (S ₁ / S ₂ ) _T0
Is a ratio of spectral line intensity values at a certain reference temperature T ₀ , ΔE is energy separation of an absorption state, h is Planck's constant, k is Boltzmann's constant, and c is speed of light). , One or more of the following variables: process pressure, fuel inlet flow rate,
Generating an electrical signal for use in adjusting the oxidant inlet flow rate. 11. A method for monitoring particle concentration levels in a monitored gas phase region of a process, comprising: (a) launching an initial collimated radiation beam emitted from a tunable diode laser along a line of sight path. Through the gas phase, and (b) collecting the emitted radiation on the side opposite to the launch position and transporting it to a photodetector having a filter element (sensitive to the wavelength of interest). And (c) tuning the laser offset from any of the resonant absorption species to monitor the attenuated radiation detected, and (d) tuning the optical signal with the laser offset from all resonant absorption spectral lines. Observed and processed the amount of attenuation from the initial beam that was observed, and the observed attenuation was measured using the particle density along the line-of-sight optical path and the following formula: (Where, I ₀ is the beam initial irradiance, I is measured irradiance after passing the process by propagating beam by a distance _{l) (I / I 0)} = exp (-a ext l) relationship pickled by _,, if the absorptance a _ext is known in the presence of particles, the measured attenuation can be related to the particle number density, and (e) based on the particle number density, one or more of the following: Variables: generating process signals, fuel inlet flow rates, electrical signal that can be used to regulate oxidant inlet flow rates. 12. A method of monitoring the rate of air intake into a combustion process, comprising: (a) determining the concentration of major combustion product species such as CO ₂ or H ₂ O initially emitted from a tunable diode laser. Emitting a collimated beam of radiation along a line-of-sight path to pass through the combustion process for measurement, and (b) collecting the emitted radiation on the opposite side of the firing position and having a filter element. Transporting to a photodetector (which is sensitive to the wavelength of interest), (c) processing the optical signal by observing the amount of attenuation observed when the laser is tuned to the resonant absorption spectral line, The integrated area of the absorption spectrum line divided by the spectrum line intensity and the path length is directly proportional to the number density at a given temperature, and (d) the air intake rate to the process And (e) an estimated air intake rate using the ambient air composition together with the inlet composition and flow rate of the oxidant and the difference between the theoretical value for complete combustion and the measured concentration of the species. Based on one or more of the following variables: generating an electrical signal for use in adjusting process pressure, fuel inlet flow rate, oxidant inlet flow rate. 13. A method for indirectly monitoring H ₂ concentration and / or hydrocarbons in a hot gas phase, comprising: (a) H ₂ O concentration initially collimated radiation beam emitted from a tunable diode laser. Is launched along a line of sight path through a gas phase (preferably flue gas of the combustion process) to measure in the spectral region where H ₂ O absorption transitions are seen, and (b) the launch location. Collecting the emitted radiation on the opposite side of the filter and transporting it to a photodetector with a filter element, and (c) the optical signal when the laser is tuned to the resonant absorption spectral line of H ₂ O. Observing and treating the amount of attenuation from the observed initial beam; (d) using the second measurement point in the gas phase region or in a diverted gas flow; (e) O ₂ Downstream of gas inlet Side H ₂ O and upstream H ₂ O are measured to calculate back the amount of H ₂ and / or unburned hydrocarbons in the gas phase, and (f) unburned H ₂ and / or Or generating an electrical signal based on the amount of hydrocarbons. 14. A pollutant X of particular interest to the process in the gas phase.
And (b) launching an initial collimated beam of radiation emitted from a tunable diode laser along a line-of-sight path through the gas phase of the process, and (b) launching position. On the side opposite to, and collecting the emitted radiation and transporting it to a photodetector having a filter element and sensitive to the spectral region of species X; Observing and processing the amount of attenuation from the initial beam observed when tuned to the resonance absorption spectral line of X, and (d) generating an electric signal based on the number density of the chemical species X. A method comprising. 15. A method of monitoring or controlling the global or local stoichiometry of an oxy-fuel combustion process operating in lean, comprising: (a) an initial collimated radiation beam emitted from a tunable diode laser. At a wavelength near 763 nm, which is accessible along the line of sight path to pass through the combustion products of the process and for O ₂ using a commercially available AlGaAs diode laser that is optically matched to the fiber. Corresponding to O ₂ BX (0,0
) Monitoring selected rotational spectral lines near the band; and (b) collecting the emitted radiation at a position substantially opposite the launch position and having a filter element and sensitivity to the O ₂ spectral region. And (c) processing the optical signal by observing the amount of attenuation from the initial beam observed when the laser is tuned to the resonant absorption spectral line of O ₂ to absorb the optical signal. The integral area of the spectral line is directly proportional to the O ₂ number density at a given temperature, and (d) based on the O ₂ number density one or more of the following variables of the oxy-fuel combustion process: process pressure, fuel Generating an electrical signal for use in controlling an inlet flow rate, an oxidant inlet flow rate. 16. A generated electrical signal informs an operator of process operating conditions and allows manual adjustment of the process by adjusting oxidant, fuel, or process pressure or any combination of these three process variables. 16. The method of claim 15, wherein 17. The method of claim 16, wherein the electrical signal is used to control the operation of one or more actuators to allow manipulation of one or more process variables. 18. A method for monitoring or controlling the global or local stoichiometry of an oxygen-fuel process operating in fuel rich conditions, comprising: (a) an initial collimated radiation beam emitted from a tunable diode laser. Are launched along a line-of-sight path to pass the combustion products of the process and are accessible to CO using a commercially available InGaAsP / InP diode laser that can be optically coupled to the fiber. Using monitoring of selected rotational spectral lines from the CO overtone band around 56 μm, and (b) collecting the emitted radiation at a position substantially opposite the launch position and having a CO with a filter element. Transporting to a photodetector sensitive to the spectral region, and Attenuation from the initial beam observed when adjusted is processed, and the integrated area of the absorption spectrum line divided by the spectrum line intensity and path length is directly proportional to the CO number density at a given temperature. And (d) generating an electrical signal for use in controlling one or more of the following variables of the oxygen-fuel combustion process: process pressure, fuel inlet flow rate, oxidant inlet flow rate, based on the CO number density. A method comprising the steps of: 19. The generated electrical signal informs the operator of the operating state of the process and allows manual adjustment of the process by adjusting oxidant, fuel, or process pressure or any combination of these three process variables. 19. The method according to claim 18, wherein 20. The electrical signal controls the operation of one or more actuators to enable manipulation of one or more process variables.
The method described in. 21. The method of claim 20, wherein increasing the flue damper area to reduce the process pressure increases air ingress and combustion with air reduces the measured CO concentration. . 22. The method of claim 20, wherein the inlet flow rate of the oxidant selected from the group consisting of oxygen-enriched air or oxygen can be adjusted to achieve a desired CO concentration for the process. 23. A method for monitoring both CO and O ₂ number densities simultaneously or substantially simultaneously at a particular location on an oxy-fuel combustion process, comprising: (a) emitting from multiple tunable diode lasers. A plurality of collimated radiation beams that are emitted along a line-of-sight path to pass through the combustion products of the process, the collimated beams having radiation at multiple wavelengths, such as 763 nm and 1.5 μm.
A step included O ₂ and CO, respectively for monitoring, (b) or simultaneously firing a plurality of variable wavelength beam by spatially introduced through emit fiber optic network, or alternatively, the multiple input beams time Introducing multiple beams at approximately the same time by splitting the laser, ie by tuning the lasers at different times, and (c) multiple frequencies using dispersive elements and / or a combination of narrow band filters and detectors. If the different wavelengths are separated and sent simultaneously, and if they are time-divided, then a single detector is used to demodulate the input signal and resolve all tuned wavelengths. , (D) processing the optical signal by observing the amount of attenuation observed when multiple beams are tuned to the resonance absorption spectral lines of a particular chemical species, The integrated area of is directly proportional to the number density of the species at a given temperature, and (e) based on the number density of the species, one or more of the following variables: process pressure, fuel inlet flow rate, oxidant inlet. Generating an electrical signal for use in controlling the flow rate. 24. A method of monitoring the temperature of the gas phase of an oxy-fuel combustion process, comprising: (a) launching an initial collimated beam of radiation emitted from a tunable diode laser along a line of sight path. Passing the combustion products of a combustion process, and (b) a diode laser from the group consisting of CO, O ₂ , H ₂ O, or other detectable process gas such as HCl that is not strongly dependent on process stoichiometry. Tuning to two or more rotating spectral lines of a selected species of choice; (c) collecting the emitted radiation at a location substantially opposite the launch location and targeting with a filter element. Transporting to a photodetector sensitive to the spectral region (sensitive to the wavelength of interest) to produce an optical signal, (d) the optical signal It was observed and process the attenuation from the initial beam observed when tuned to two or more resonance spectrum lines, the following equations temperature, Equation 2] (Where R is the ratio of integrated absorption of each transition at an unknown temperature T, (S ₁ / S ₂ ) _T0
Is a ratio of spectral line intensity values at a certain reference temperature T ₀ , ΔE is energy separation of an absorption state, h is Planck's constant, k is Boltzmann's constant, and c is speed of light). And generating one or more of the following variables of the oxy-fuel combustion process: process pressure, fuel inlet flow rate, generating an electrical signal for use in adjusting the oxidant inlet flow rate. 25. A method for monitoring a particle concentration level in a monitored gas phase region of an oxy-fuel combustion process, comprising: (a) an initial parallel radiation beam emitted from a tunable diode laser to a line of sight path. Firing along to pass the gas-phase combustion products of the process; (b) on the side opposite the firing position, the emitted radiation is collected and a photodetector with a filter element (of interest) Sensitive to wavelengths), (c) tune the laser offset from any resonant absorbing species to monitor the attenuated radiation detected, and (d) send the optical signal to the laser. Observe and process the amount of attenuation from the initial beam that is observed when tuning is performed by shifting from all resonance absorption spectral lines, and the observed attenuation is converted into line-of-sight light. And particle density along the following _{formula, (I / I 0) =} exp (-a ext l) ( where, I ₀ is the beam initial irradiance, I is passed through the process by propagating beam by a distance l (E) the particle number density, if the absorptance a _ext is known when the particles are present, the measured attenuation can be related to the particle number density. Generating one or more of the following variables of the oxy-fuel combustion process: generating an electrical signal that can be used to adjust the process pressure, fuel inlet flow rate, oxidant inlet flow rate. Method. 26. A method for monitoring the rate of air uptake into an oxy-fuel combustion process, comprising: (a) emitting a concentration of major combustion product species such as CO ₂ or H ₂ O from a tunable diode laser. Firing an initial collimated beam of radiation along a line-of-sight path through the oxy-fuel combustion process to measure, and (b) collecting the emitted radiation opposite the firing location. Transport to a photodetector with a filter element (which is sensitive to the wavelength of interest), and (c) the optical signal, the attenuation observed when the laser is tuned to the resonant absorption spectral line. Observed and processed, the integrated area of the absorption spectrum line divided by the spectrum line intensity and path length is directly proportional to the number density at a given temperature, and (d) air to the process. Estimating the intake rate using the ambient air composition along with the fuel and oxidant inlet and flow rates and the difference between the theoretical and measured concentration of the species for complete combustion; and (e) estimating Generating one or more of the following variables based on the air intake rate: process pressure, fuel inlet flow rate, oxidant inlet flow rate, and generating an electrical signal for use in adjusting. 27. Oxygen - and H ₂ concentration and / or hydrocarbons in the hot gas stream of the fuel combustion process be indirect monitoring methods, the (a) H ₂ O concentration, emission from tunable diode lasers An initial collimated beam of radiation is launched along a line-of-sight path and passed through the gas phase region of the process (preferably the flue gas of the combustion process), measured in the spectral region where H ₂ O absorption transitions are found. And (b) collecting the emitted radiation on the side opposite the launch position and transporting it to a photodetector with a filter element, and (c) sending an optical signal to the H ₂ O resonance of the laser. Observing and processing the amount of attenuation from the initial beam observed when tuned to the absorption line, and (d) the second measurement point in the gas phase region or in the bypassed gas flow. so The step used and (e) the difference between H ₂ O on the downstream side and H ₂ O on the upstream side of the O ₂ gas introduction part is measured to determine the amount of H ₂ and / or unburned hydrocarbons in the process stream. A method comprising: back calculating and (f) generating an electrical signal based on the amount of unburned H ₂ and / or hydrocarbons. 28. Species X of particular interest to oxygen-fuel combustion processes.
(A) launching an initial collimated beam of radiation emitted from a tunable diode laser along a line-of-sight path to pass combustion products of a combustion process; and (b) Collecting emitted radiation on the side opposite to the launch position and transporting it to a detector with a filter element, and (c) an optical signal to tune the laser to the resonant absorption spectral line of species X. A method comprising the steps of observing and processing the amount of attenuation from the initial beam that is sometimes observed, and (d) generating an electric signal based on the number density of the chemical species X. 29. An apparatus for monitoring a chemical species X of particular interest to a process for: (a) launching an initial collimated beam of radiation along a line-of-sight path to pass through the gas phase of the process. A tunable diode laser of (b) a collection capable of collecting emitted radiation at a location substantially opposite the tunable diode laser and transporting the collected radiation to a photodetector having a filter element. And (c) an optical processor for observing the attenuation of the initial beam when the initial beam is tuned to the resonance absorption spectral line of the chemical species X. Means for generating a signal.