Download or read book Investigation of Tunable Diode Spectroscopy for Monitoring Gases in Geothermal Plants written by J. K. Partin and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of an investigation directed at the development of instrument-tation for the real-time monitoring of gases, such as hydrogen sulfide (H2S) and chloride (HCl), in geothermal process streams is described. The geothermal power industry has an interest in the development of new low maintenance techniques since improved capabilities could lead to considerable cost savings through the optimization of various gas abatement processes. Tunable diode laser spectroscopy was identified as a candidate tech-nology for this application and a commercial instrument was specified and procured for testing. The measurement principle involved the use of solid state diode lasers and frequency modulation techniques. The gallium arsenide diode lasers employed emit light in the 0.7 to 2.0 micron region of the electromagnetic spectrum. This region contains the overtone and combination absorption bands of a number of species of industrial interest, including H2S and HCl. A particular device can be tuned over a small range to match the absorption line by changing its applied temperature and current. The diode current can also be sinusoidally modulated in frequency as it is tuned across the line. This modulation allows measurements to be conducted at frequencies where the laser intensity noise is minimal; and therefore, very high signal-to-noise measurements are possible. The feasibility of using this technology in various types of geothermal process streams has been explored. The results of laboratory and field studies are presented along with new advances in laser technology that could allow more sensitive and selective measurements to be performed.
Download or read book Trace Gas Monitoring by Open path Tunable Diode Laser Absorption Spectrometer OP TDLAS written by University of Victoria (B.C.). Centre for Earth and Ocean Research and published by . This book was released on 1996* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geothermal written by Geothermal Resources Council. Meeting and published by . This book was released on 1998 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monitoring Gas Concentrations in Environmental and Atmospheric Applications Using Tunable Diode Lasters written by Andrew Awtry and published by . This book was released on 2004 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gas Sensing in Industry by Tunable Diode Laser Spectroscopy TDLS written by Maximilian Lackner and published by . This book was released on 2008 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1978 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Indirect Gas Species Monitoring Using Tunable Diode Lasers written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A method for indirect gas species monitoring based on measurements of selected gas species is disclosed. In situ absorption measurements of combustion species are used for process control and optimization. The gas species accessible by near or mid-IR techniques are limited to species that absorb in this spectral region. The absorption strength is selected to be strong enough for the required sensitivity and is selected to be isolated from neighboring absorption transitions. By coupling the gas measurement with a software sensor gas, species not accessible from the near or mid-IR absorption measurement can be predicted.
Download or read book Environmental Application of High Sensitive Gas Sensors with Tunable Diode Laser Absorption Spectroscopy written by Xiaojuan Cui and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the fact of global warming, air quality deterioration and health concern over the past few decades, great demands and tremendous efforts for new technology to detect hazard gases such as CH4, CO2, CO, H2S, and HONO have been performed. Tunable diode laser absorption spectroscopy (TDLAS) is a kind of technology with advantages of high sensitivity, high selectivity, and fast responsivity. It has been widely used in the applications of greenhouse gas measurements, industrial process control, combustion gas measurements, medicine, and so on. In this chapter, we will briefly summarize the most recent progress on TDLAS technology and present several kinds of gas sensors developed mainly by our group for various field applications. These could expand from energy, environment, and public safety to medical science.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1984 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Earth Resources written by and published by . This book was released on 1976 with total page 910 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multiple Gas Specie Detection Using a Tunable Diode Laser Sensor for Combustion Process Monitoring written by William Von Drasek and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Utilization of Multiple Harmonics of Wavelength Modulation Absorption Spectroscopy for Practical Gas Sensing written by Kai Sun and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To meet more rigorous criteria for environmental-unfriendly emissions and to increase energy efficiency, in-situ real-time sensors are needed to optimize the performance of next-generation energy systems. The emergence of high-quality (narrow linewidth, fast tuning capability) tunable diode lasers (TDLs) has enabled the use of wavelength modulation spectroscopy (WMS) for harsh industrial applications. Compared to conventional direct absorption measurements, WMS has the advantage of 10-100 times better detection sensitivity, avoids the need to obtain a zero-absorption baseline, and provides much better isolation from the beam steering, non-absorption transmission loss (e.g., light scattering) or mechanical vibrations. Many models have been developed to interpret the measured WMS signal into absolute absorption. However, most of these models are limited to specific applications by a wide variety of assumptions and approximation most of which deal with the simultaneous intensity and wavelength modulation of injection-current-modulated diode lasers. In this dissertation, two generalized approaches to analyze the WMS absorption signal were developed that account for non-ideal simultaneous intensity modulation of laser output when injection current variation is used for wavelength modulation. The first approach is ideal for wavelength-fixed WMS (the laser mean wavelength is fixed) analysis and the second approach is ideal for wavelength-scanned (the laser mean wavelength is scanned) WMS analysis, and both of them can be used for arbitrary modulation depth, or laser architectures even when severe non-linear intensity modulation occurs simultaneously with wavelength modulation. These new interpretations of WMS absorption signals provide the potential for extended and improved use of WMS for practical gas sensing in a much wider array of applications. The first approach built on earlier work in our laboratory. The analysis of calibration-free, 1f-normalized, WMS-2f absorption signals was extended to higher harmonics (for example 3f, 4f ...) using traditional Fourier analysis. The new approach and procedure developed also accounts for non-ideal wavelength-tuning of the injection-current tuned laser as well as etalon interference from the optical components in the laser line-of-sight (LOS). This approach was validated using measurements of the CO transition of R (11) in the 1st overtone band near 2.3æm in a laboratory cell at room temperature for a range of CO mole fractions (0.21-2.8%) and pressures (5-20atm). For high-pressure gas sensing, wavelength modulation spectroscopy with higher-order harmonic detection (WMS-nf, n> 2) was found to have less influence from the WMS background signals when the selected modulation depth was near the optimal modulation depth for the WMS-2f signal. This WMS approach was then used for measurements in a pilot-scale entrained-flow coal gasifier at the University of Utah. Even though the particulate scattering reduced the laser transmission as much as 99.997%, and pressure broadening at the 18atm (~250psig) operating pressure blended the absorption transitions, successful in-situ rapid-time-resolved 1f-normalized WMS-2f absorption measurements for gas temperature and H2O mole fraction were made. Based on lessons learned during the gasifier measurements at Utah and a desire to eventually develop real-time sensors for long-term monitoring, a second approach for WMS analysis was developed that differs from previous WMS analysis strategies in two significant ways: (1) the measured laser intensity without absorption is used to simulate the transmitted laser intensity with absorption and (2) digital lock-in and low-pass filter software is used to expand both simulated and measured transmitted laser intensities into harmonics of the modulation frequency, WMS-nf (n=1,2,3 ...), avoiding the need for an analytic model of intensity modulation or Fourier expansion of the simulated WMS harmonics. The new method was demonstrated and validated with WMS of H2O dilute in air (1atm, 296K, near 1392nm). WMS-nf harmonics for n=1 to 6 are extracted and the simulations and measurements are found in good agreement for the entire WMS lineshape. This new analysis scheme was applied to monitor the synthesis gas output from an engineering-scale transport reactor coal gasifier at the National Carbon Capture Center. There the pressures ranged up to 15 atm (~220psig) and temperatures up to 650K. Continuous monitoring of moisture level in the gasifier output with 2s time resolution was performed by the TDL sensor for more than 500 hours, including the periods of burner ignition, combustion heating with a propane flame, coal combustion, coal gasification, and reactor shut-down via coal-feed termination. In addition, a novel and rapid approach to determine the collisional linewidth via the WMS signals at different harmonics at the modulation frequency is presented. The peak values of the WMS-nf absorption spectrum near the transition line center are used to infer the absorption lineshape, which is exploited here to extract collision-broadening halfwidth from the ratio of WMS-4f/WMS-2f (or other even harmonics) signals when the mean laser wavelength is tuned to line center. Measurement of the absorption linewidth enables quantitative WMS measurements without the need for a collision-broadening database. Alternatively, when collision-broadened spectral data are available, a WMS-based pressure sensor can be realized, and a demonstration using the 4fpeak/2fpeak ratio gives less than 0.7% difference for the pressure for cell measurements from 100 torr to 753 torr. These new WMS analysis schemes have been validated in near commercial environments and illustrate the potential of their use to develop practical TDL sensors for a wide variety of industrial applications.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Near infrared Tunable Diode Laser Absorption Spectrometer for Trace Gas Detection written by Iain Fletcher Howieson and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Acid Precipitation written by and published by . This book was released on 1983 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Euro Abstracts written by and published by . This book was released on 1989 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1976 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:
