Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Imaging apparatus characterizes drops in ’dirty’ laboratory environments

20.09.2002


A high-fidelity spectrometric system for studying the behavior of drops and particles in industrial flame reactors has been constructed by researchers at the University of Illinois at Urbana-Champaign in collaboration with researchers at the University of Arizona. The instrument was used to study the potential of thermal combustors for reducing the volume of liquid nuclear wastes for safe, long-term storage.



Vitrification of radioactive waste into glassy solids is the most popular approach for disposal. By spraying radioactive sludge into a high-temperature combustor, essentially all the water and other nonradioactive material could be removed, leaving only the radioactive metallic elements to be vitrified for burial. Under optimized conditions, up to 99.99 percent of the metal ions in a waste stream can be scavenged in the combustor.

"That kind of efficiency would be great for most applications, but it’s not good enough when dealing with radioactive waste," said Alexander Scheeline, a professor of chemistry at Illinois. "Understanding the cause of the unscavenged fraction and devising a way to reduce it are essential if thermal processing is to be used for nuclear waste treatment."


One possible explanation is that large "rogue" drops are responsible for the unscavenged metals, Scheeline said. These drops do not pass through the hottest zones in the combustor, resulting in only partial vaporization.

To investigate the role of rogue drops in this process, Scheeline and his colleagues --Illinois postdoctoral researcher Jerry Cabalo, Arizona professor and head of chemical and environmental engineering Jost Wendt, and Arizona graduate student John Schmidt -- developed an optical system to monitor drop sizes and trajectories at very high spatial resolutions.

"In the thermal waste destruction process, small particle formation is also very important," Scheeline said. "Metals released into the gas phase readily form small particles, so it was crucial that this system also have the capability of detecting small soot particles."

In operation, large drops of water or diesel fuel were injected into the furnace. An excimer laser sent a beam into the combustor, illuminating a plane through which the drops passed. The scattered light was then passed to a CCD (charge-coupled device) camera and analyzed.

In contrast to optical monitoring of typical combustion experiments performed in a reasonably clean environment, "these measurements took place in a coal combustion laboratory at the University of Arizona," Scheeline said. "Coal dust from experiments and sand from the desert were all-too-frequent visitors."

To protect delicate optical components, the researchers covered the optical system with plastic panels and pumped clean, dry air into the enclosure. "Despite months of experiments on coal dust combustion taking place in the laboratory -- which left a thick layer of dust on the outside of the spectrograph and on the plastic housing -- the optical path remained free of dust and other contaminants," Scheeline said.

In their initial studies, the researchers demonstrated that the optical system could track large drops and the resulting soot particles through the flame. "To get these drops to break up and vaporize, we need a longer combustion zone, or we need to spray finer drops," Scheeline said.

The same kind of optical measurements and combustion research is relevant to designing cleaner-running automobile engines, studying combustion processes in rocket engines, and developing alternative means for solid waste disposal.

The researchers describe their instrumentation and experiments in the October issue of Applied Spectroscopy. The U.S. Department of Energy supported this work.

Jim Kloeppel | UIUC

More articles from Process Engineering:

nachricht Fraunhofer researchers develop measuring system for ZF factory in Saarbrücken
21.11.2017 | Fraunhofer-Institut für Zerstörungsfreie Prüfverfahren IZFP

nachricht New manufacturing process for SiC power devices opens market to more competition
14.09.2017 | North Carolina State University

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New proton record: Researchers measure magnetic moment with greatest possible precision

High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons

The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

IceCube experiment finds Earth can block high-energy particles from nuclear reactions

24.11.2017 | Physics and Astronomy

A 'half-hearted' solution to one-sided heart failure

24.11.2017 | Health and Medicine

Heidelberg Researchers Study Unique Underwater Stalactites

24.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>