Proceedings Volume 3108

Combustion Diagnostics

Maurus Tacke, Winfried Stricker
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Proceedings Volume 3108

Combustion Diagnostics

Maurus Tacke, Winfried Stricker
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Volume Details

Date Published: 23 May 1997
Contents: 4 Sessions, 18 Papers, 0 Presentations
Conference: Environmental Sensing III 1997
Volume Number: 3108

Table of Contents

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Table of Contents

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  • REMPI
  • In-Situ Techniques
  • In-Situ Techniques and Infrared Techniques
  • Poster Session
REMPI
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Resonance ionization mass spectrometry and its application to trace analysis of emissions from combustion engines
Ulrich Boesl, Holger Nagel, Ralf Zimmermann, et al.
The principle of resonance-ionization mass spectrometry with lasers is the combination of two analytical tools, UV- spectroscopy in the gas phase and time-of-flight mass selection. The special features of this combination are: very high selectivity, high speed, multicomponent ability, and adaptability to many different problems. Examples for the latter are on-line trace analysis of emissions from combustion processes, such as from combustion engines as well as from municipal incinerators. But also monitoring of industrial procedures, e.g. food processing, are interesting applications of REMPI-MS. In this paper the principles will be shortly explained and results for the analysis of exhaust emissions from motorized vehicles presented.
Application of resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) for on-line trace analysis of combustion and pyrolysis products in technical processes
Ralf Zimmermann, H. J. Heger, R. Dorfner, et al.
We present first applications of resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) for on-line monitoring of technical water incinerator flue gases and coffee roasting process off- gases. The results were obtained with a newly developed, mobile REMPI-TOFMS device. The combination of laser induced resonance-enhanced multiphoton ionization and time-of-flight mass spectrometry represents a highly selective as well as sensitive analytical technique, well suited for species selective real-time on-line monitoring of trace-products in of-gases from thermal processes or technical incinerators. The achievable sensitivities are in the ppb-range or better for aromatic compounds. The high selectivity is due to the combination of mass- and optical selectivity, the high sensitivity is caused by the high cross sections of resonance-enhanced two photon ionization with lasers. On- line monitoring of trace chemicals, formed during combustion- or pyrolysis-processes, is useful e.g. for feed back steering of combustion processes in order to minimize the formation of hazardous byproducts or for optimization of the economic efficiency of thermal production processes.
Jet-REMPI for process control in incineration
Harald Oser, Reinhold Thanner, Horst-Henning Grotheer, et al.
The mobile Jet-REMPI apparatus is an optimized variant of the conventional REMPI mass spectrometry which is known for its selectivity and on-line capability. By shifting the ionization volume from the molecular regime of the sample beam as in conventional arrangements, to the vicinity of the jet, a significant sensitivity improvement was achieved without loss in the other favorable features of this technique. The laboratory set-up was converted into a mobile unit so that the technique could be field-tested. The experimental test reactor KLEAA was developed in order to simulate grate incineration under well-defined conditions. To this end selected waste samples of up to 3 kg mass are taken as fuel and are connected to the bottom end of a pre- heated cylindrical combustion chamber which is equipped with heating elements to allow for a variable temperature profile. Measurable quantities include velocities of ignition and of combustion, mass loss rate of the sample, and pollutants along with permanent gases such as CO, CO2, O2 in the exhaust gas line. The coupling of these machines served two purposes: (a) to test Jet-REMPI under realistic conditions and to study its requirements with regard to sampling techniques, (b) to better characterize and understand the non-stationary behavior of the KLEAA reactor which is operated batch-wise. For these measurements wood diluted with suitable inert material was taken as a fuel, i.e., an essentially chlorine-free situation prevailed. Samples were drawn downstream of the filter. The Jet-REMPI measurements constitute the first field measurements carried out with this method. The monitored compounds include typical products of incomplete combustion such as phenol, benzene, naphthalene, fluorene and other compounds. As a drawback it turned out that particulates cannot be tolerated in the REMPI ion source because they lead to non-resonant contributions which are recorded as noise.
In-Situ Techniques
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Beam-steering effects in turbulent high-pressure flames
Bernd Hemmerling
The propagation of a laser beam through a flame is influenced by variations of the refractive index. This can limit the application of laser diagnostic methods in turbulent high-pressure flames. On the other hand, one can gain some insight into the turbulence structure of such flames by analyzing the speckle patterns which appear in the transmitted laser light.
AEROJET: nonintrusive measurements of aircraft engine exhaust emissions
Klaus Schaefer, Joerg Heland, Roger Burrows, et al.
The environment impact of air traffic and economical aspects require aircraft engines to be developed which have reduced trace gas emissions and, at the same time, increased efficiency. Each new engine must be shown to meet the environmental requirements laid down by regulatory bodies, and exhaust gas measurements must be performed for the certification. The goal of the EC project AEROJET is to demonstrate the equivalence of remote measurement techniques to conventional extractive methods for both gaseous and particulate measurements. The different remote measurement techniques will be compared and calibrated. A demonstrator measurement system for exhaust gases, temperature and particulates including data-analysis software will be regarded as result of this project.
In-Situ Techniques and Infrared Techniques
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Infrared temperature measurement of burning droplet
Olivier Ravel, Nicolas Naudin, Olivier Adam, et al.
This paper describes the IR optical system technic used for droplet surface temperature measurements in combustion. The experimental set up is composed of two off axis parabolic mirrors, a detector and an electronic data acquisition and processing unit. Droplets with 200 micrometers diameters and velocity about 5m/s are investigated. In order to study the feasibility of the droplet temperature measurement during combustion process, the ethanol flame spectral emission has been measured with an IR spectrometer. For these operating conditions, we could draw the apparent droplet temperature along the droplet stream. These results show that in all cases, the apparent droplet temperature has an asymptotic behavior along the stream. The real droplets temperature can be obtained by a precise estimate of all thermal fluxes.
Automotive exhaust gas analysis by infrared tunable diode laser absorption spectroscopy
Yolande Louvet, Eric de Borniol, Daniel Henry, et al.
Engine management optimization and waste exhaust-gas control require engine transients measurements. The infrared tunable diode laser absorption spectroscopy method can measure absolute molecule concentrations, gas temperature and pressure at high rate. The technique has been improved to measure NO or CO concentrations, as well as temperature and pressure of engine exhaust-gas. Measurements with a time resolution of one millisecond have been achieved in one of the cylinder exhaust pipe without any gas sampling.
Poster Session
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Detection of nitrogen oxides by high-resolution near-infrared absorption spectroscopy
Manazumi Tanoura, Kenji Muta, Kohtaro Fujimura, et al.
Near-infrared absorption spectra of NO, NO2 and N2O were observed in the wavelength region between 1.2 and 1.9 micrometers using a high-resolution Fourier-transform spectrometer, and we have obtained precise absorption data which are useful for tunable diode laser absorption spectroscopy (TDLAS). Furthermore, the NO and N2O were detected by means of TDLAS method for the first time using InGaAs-DFB diode lasers which were designed to access absorption lines at wavelengths of 1.798 and 1.766 micrometers respectively.
Simultaneous detection of oxygen and soot particles by visible diode laser absorption spectroscopy
Kenji Muta, Manazumi Tanoura, Kohtaro Fujimura, et al.
A technique for simultaneous detection of oxygen molecules and soot particles by means of visible tunable diode laser absorption spectroscopy was investigated. The effects of solid particles on the measurement of oxygen molecules were evaluated using a 760 nm visible diode laser. The maximum solid particle density was 5.6g/m3m, allowing measurement of the concentration of oxygen with sufficient precision. We applied this technique to analysis of real exhaust gas from a large-scale test furnace, and verified that oxygen molecules and soot particles in such gas can be directly measured from a large-scale test plant without pretreatement, such as removal of water vapor and soot.
Temperature measurement by laser-induced fluorescence of nitric oxide in combustion flame
Masafumi Yorozu, Yasuhiro Okada, Akira Endo
2D rotational temperature measurement was performed in a stable combustion flame of premixed butane and oxygen using multiline laser induced fluorescence (LIF) of nitric oxide (NO) molecules. The rotational lines of the $gama bands of NO were excited by laser light around 226 nm, and the LIF signal was observed by an image-intensified digital camera. Temperature was determined through least square fitting correlation between LIF intensity and excitation rotational quantum number for the Boltzmann distribution function. The measured LIF intensity was approximated by the Boltzmann distribution with good accuracy, and the temperature obtained was between 500K and 1800K for the test flame. The measuring error of the temperature was evaluated and found to be 80K, which corresponded to 8 percent of the measured fluorescence intensity. The two-line LIF scheme was evaluated for comparison with the multiline LIF approach. Temperature which was obtained by two-line LIF scheme corresponded well with multiline LIF results for Q1(31.5)/Q1(16.5) excitation. However, for Q1(18.5)/Q1(16.5) excitation, the obtained temperature did not agree with the multiline LIF result because the population of rotational states J equals 18.5 and J equals 16.5 is similar at high temperatures. We found that two-line LIF temperature measurement was reliable when excitation lines were suitably selected.
Combustion diagnostic using degenerate four wave mixing spectroscopy
The DFWM, used as a laser spectroscopy for gas phase trace detection,is receiving a great deal of attention in combustion diagnostics. In this technique three laser beams, tuned at the same wavelength, interfere in a gaseous medium containing a resonant species. Two laser beams, interacting with the (chi) 3 of the medium, generate a grating which is read by the third laser and scatters the signal beam at the same wavelength. The NO molecule and OH radical have been detected in small undoped flames by performing space resolved concentration and temperature measurements in forward BOXCARS geometry. The NO space distribution has been investigated in a C2H2/air flame by exciting the (gamma) transition around 226 nm. Flame temperature and NO concentration have been calculated after calibration on room temperature cell data. The OH DFWM spectrum of the A2(Sigma) +-X2(Pi) vibrationally excited transition peaked around 284 nm has ben recorded in C2H2/air and isobuthane/air flames, corresponding flame temperatures have been determined. The possibility of NO2 detection in flame outlets has been investigated by studying the effects of collisional energy redistribution on its Douglas-Huber band DFWM spectrum measured in air mixtures at different pressures and temperatures.
Optical measurement of the sodium concentration in the gas stream of a 1-MWth coal powder reactor at 1300oC and 13 bar
Peter Kohns, R. Stoermann, W. Christmann, et al.
In practice, an upper limit of the temperature of the gas stream in thermal power plants arises from the corrosive effect of several contents which damage the turbine material, in particular sodium atoms. Thus the increase of the efficiency requires the on-line measurement of the sodium concentration. In order to install a protection of the turbines we carried out atomic absorption measurements of the sodium concentration in the gas stream of an experimental coal powder reactor with a thermal power of 1 MW. Pressure and temperature of the gas stream were 13 bar and 1300 degrees C, respectively. We found considerable fluctuation of the sodium concentration at a time scale of several seconds, especially when the operation conditions of the reactor were changed. The obtained temporal resolution was 0.3 sec. This value is sufficient to control the combustion process.
New spectral selection system for infrared imaging of carbon monoxide in combustion environments
Jesus Meneses, Susana Briz, Antonio J. de Castro, et al.
In this work, a new spectral selection system for imaging of CO infrared emission in combustion environments is proposed. The CO and CO2 medium infrared emission bands are spectrally overlapped, so cross-talk effects would appear when trying to image CO using a IR camera equipped with a conventional band-pass filter. The system proposed belongs to a new family of infrared multilayer filters, called solid state Fabry-Perot (SSFP) filters. The transmittance of such filters can be spectrally matched to the CO fine structure emission band. Thus, it is possible to discriminate the CO emitted IR radiation from that which comes from CO2 in combustion environments. With a Fourier Transform Infrared spectroradiometer, we have studied and spectrally characterized the IR emission from hydrocarbon flames, varying the O2 inlet, i.e. the CO generated. Using these experimental data and the theoretical spectral transmission for both band-pass filter and the SSFP filter, we have demonstrated the uselessness of the former and the suitability of the latter, in order to discriminate CO and CO2. A silicon wafer, both sides covered by a reflecting multilayer, is proposed as a SSFP. The design and spectral parameters of such a filter are developed on the basis of the optical properties of the multilayers and substrate, and specific designs for CO imaging are presented.
Selective remote diagnostics of gaseous hydrocarbon flames
Valery D. Antsygin, Sergei M. Borzov, Victor I. Kozik, et al.
An optoelectronic remote method of gaseous flame parameters determination is suggested. It is based on the principles of passive optical spectroscopy with the use of a receiving radiation of tongues followed by electronic digital data processing. The radiation is registered in green-blue range of spectrum by multielement semiconductor photodetector with a predominant use of one spatial coordinate and optical integration along the other coordinate. The digital data processing is performed by means of local and pointwise image processing operators.
Use of an airborne laboratory as an integrated instrumentation complex for the investigation of emissions from industrial enterprises
Boris D. Belan, Mikhail Yu. Arshinov, Gennadii N. Tolmachev
Airborne laboratories are used for the estimation of the environmental state during several tens of years. However, the results obtained with such labs are incomplete, it follows from the analysis made. If the aircraft equipped with contact means, they provide information only on one or two ingredients, if remote systems are installed on it, then it is possible to acquire information on vertical profiles or spectral response of the underlying surface. Experience accumulated in IAO SB RAS during airborne sounding of cities and areas shows that if all measurement systems are combined into an integrated complex, then information on environmental state exhibits a new quality. At the same time some conditions should be achieved. First of all, the airborne laboratory should be equipped with contact as well as with remote devices which duplicate measurement of the same parameters. This allows to obtain more reliable data s well as to calibrate remote devices using contact data. Second, all measurement instruments should be combined into a united information system to make synchronous measurements. In this case data from different instruments complement each other. Third, all three media, i.e. soil, water, and air should be controlled by means of remote and contact means, that will essentially facilitate data interpretation.
Results of direct measurements of aerosol composition in emissions from several enterprises in Russia and Kazakhstan
Boris D. Belan, Mikhail Yu. Arshinov, D. V. Simonenkov, et al.
These measurements have been carried out directly by sampling on filters in the emission plumes by means of airborne laboratory. Then filters have been analyzed in laboratory conditions. The analysis allowed the determination of the concentration of 12 ions and 27 elements. Average concentration of each emission component has been determined from known air volume passed through the filer. Wind speed has been measured at the crossing of the emission plume whose area is found from lidar data. This allows us to find the average concentration of contaminants in the emission as well as the emission gross yield. In this paper we present the data on the composition of emissions from enterprises of Pavlodar, Khabarovsk, Komsomolsk-on- Amur, Nizhnevartovsk, and Nizhnii Tagil.
Database compiled based on the results of monitoring atmospheric emissions from industrial enterprises
Tatyana K. Sklyadneva, Boris D. Belan
Since 1981 the Institute of Atmospheric Optics started regular airborne sounding of the atmosphere. As a result vast observational materials has been compiled during the last decade. In fact three generations of computers changed in the course of airborne missions onboard, first IL-14 and then AN-30 aircrafts. Therefore the data have been stored in different formats and on different data media. In this connection it happened to be an urgent task at present to rewrite the whole data bulk in one an the same format. Thus created database involves three types of data sets, i.e. profiles acquired during the ascends and descends, data collected along horizontal flights, and data on chemical composition of air including data obtained with analytical techniques in laboratory. This database has been included into the list of databases at the Information Center of the National Committee of the Russian Academy of Sciences. During the period from 1989 till 1991 several ecological surveys have been performed with an 'Optik E' airborne laboratory on board an AN-30 aircraft over a number of cities. The database compiled during these missions has similar to the above database structure. It differs from that by additional blocks of information on flight routes necessary for mapping air pollutions. Data sampled inside stack plumes from plants with the aircraft and data collected with a ground-based mobile station also differ it from that database.
Continuous multicomponent stack gas analyzer using ultraviolet-photodiode-array spectroscopy
Derek D. Stuart
Ammonia injection is frequently used to reduce emissions of nitrogen oxides from modern combustion plant. Accurate measurements of ammonia and nitric oxide are therefore required to ensure optimum operation of the NOx control system. Measurements of sulphur dioxide are also required to ensure compliance with legislation in most countries. An extractive analytical system has been developed for continuous measurements of ammonia, nitric oxide and sulphur dioxide concentrations in stack gases based on an ultraviolet spectrometer using a photodiode array detector operating in the 200nm region. The use of the photodiode array spectrometer enables the system to have a fast response time while maintaining excellent wavelength stability and reliability, since there are no moving parts in the main optical system. A high temperature sampling system is coupled to a hot sample cell to ensure that there is no degradation of the sample prior to measurement. Tests in the laboratory and at a combustion plant in Europe have shown practical detection limits of 1ppm for all of the target gases.