| 1. |
- Sandsten, Jonas
(författare)
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Development of infrared spectroscopy techniques for environmental monitoring
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Infrared spectroscopy techniques have long been utilized in identifying and quantifying species of interest to us. Many of the elementary molecules in the atmosphere interact with infrared radiation through their ability to absorb and emit energy in vibrational and rotational transitions. A large variety of methods for monitoring of molecules and aerosol particles by collecting samples or by using remote sensing methods are available. The objective of this thesis work was to develop infrared spectroscopic techniques to further enhance the amount of useful information obtained from gathering spectral data. A new method for visualization and quantification of gas flows based on gas-correlation techniques was developed. Real-time imaging of gas leaks and incomplete or erratic flare combustion of ethene was demonstrated. The method relies on the thermal background as a radiation source and the gas can be visualized in absorption or in emission depending on the temperature difference. Diode laser spectroscopy was utilized to monitor three molecular species at the same time and over the same path. Two near-infrared diode lasers beams were combined in a periodically poled lithium niobate crystal and by difference-frequency generation a third beam was created, enabling simultaneous monitoring of oxygen, water vapor and methane. Models of aerosol particle cross sections were used to simulate the diffraction pattern of light scattered by fibers, spherical particles and real particles, such as pollen, through a new aerosol particle sensing prototype. The instrument, using a coupled cavity diode laser, has been designed with a ray-tracing program and the final prototype was employed for single aerosol particle sizing and identification.
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| 2. |
- Sandsten, Jonas, et al.
(författare)
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Gas visualization of industrial hydrocarbon emissions
- 2004
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Ingår i: Optics Express. - 1094-4087. ; 12:7, s. 1443-1451
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Tidskriftsartikel (refereegranskat)abstract
- Gases leaking from a polyethene plant and a cracker plant were visualized with the gas-correlation imaging technique. Ethene escaping from flares due to incomplete or erratic combustion was monitored. A leakage at a high-pressure reactor tank could be found and visualized by scanning the camera system over the industrial site. The image processing methods rely on the information from three simultaneously captured images. A direct and a gas-filtered infrared image are recorded with a split-mirror telescope through a joint band-pass filter. The resulting path-integrated gas concentration image, derived from the two infrared images, is combined with a visible image of the scene. The gas-correlation technique also has the potential to estimate the flux in the gas plume by combining a wind vector map, derived by cross-correlating the images in time, with a calibrated gas path-integrated concentration image. The principles of the technique are outlined and its potential discussed.
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| 3. |
- Sandsten, Jonas, et al.
(författare)
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Volume flow calculations on gas leaks imaged with infrared gas-correlation
- 2012
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Ingår i: Optics Express. - 1094-4087. ; 20:18, s. 20318-20329
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Tidskriftsartikel (refereegranskat)abstract
- Two methods for volume flow calculation from images of methane leakages to the atmosphere are presented. The images contain calibrated gas concentration x path length pixel information, and are processed with a block matching method and a theoretical velocity field method. Results from known methane flow in two laboratory setups and one unknown real leakage from a gas processing plant are compared with the image processing methods. The methods are generic and can be implemented in common infrared systems for gas visualization. This work provides a new tool for estimating and reporting volume flow emissions from gas processing plants to the authorities. (C) 2012 Optical Society of America
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