New device curbs greenhouse gas emission
13/9/2007 9:59
Technologists have developed a new industrial device to purify methane
from coal-bed gas, finding a solution to reduce a big chunk of China's
greenhouse gas emission.
Yang Kejian, a veteran technologist at the
Technical Institute of Physics and Chemistry under the Chinese Academy of
Sciences (CAS), led his research team to develop the device, which is used for
sucking coal-bed gas, a combination of methane, oxygen and nitrogen, and
producing highly-purified methane, a clean energy equivalent to natural
gas.
As key steps in their experiment, Yang and his team installed two
sets of such device on two different coal pits in Yangquan and Jincheng, both
big coal fields in north China's Shanxi Province.
Using the device like a
huge refrigerator, the technologists froze the combined coal-bed gas under 200
degrees Celsius below zero, and separated methane, oxygen and nitrogen from each
other thanks to their different evaporation points, Yang said.
"The
technology not only produces commercialized methane, but also helps reduce
greenhouse effect resulting from randomly emitted methane to the air," Yang
said.
The usually combined coal-bed gas, which is highly explosive if
aggregating to a certain density, also poses deadly threat to coal
miners.
Coal mine blasts are often triggered by the gas and coal mining
firms have not found better ways than pumping the coal-bed gas out of pits and
letting it melt in the air.
Statistics show that China has the world's
biggest reserve of coal-bed gas, three times that of the United States. But
unlike America, most of the precious coal-bed gas has not been collected or
utilized.
The Yangquan coal mines, one of the country's largest 13 coal
production bases, accounted for one fifth of the total coal-bed gas emission.
Therefore, Yang and his team negotiated with Yangquan Coal Co. for a test on the
experimental device.
All the three major components of the coal-bed gas
could be effectively used, said Zhang Wu, chief architect and lead engineer of
the project.
"We got 99 percent purified methane which could be directly
packaged for consumers, oxygen is okay for certain purposes or just to be
released into the air, and nitrogen is used for adding coolant," Zhang
said.
After comparing other techniques in separating methane from the
mingled gas, Zhang said he feels confident about their low-temperature
fractionation method. With computer analyses, the research team built more than
10 models for the best possible choice.
A Beijing-based venture capital
company financed the green-energy project. The private company invested roughly
10 million yuan (US$1.32 million) in the two experimental
devices.
Xinhua
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