As described in ASM International's Advanced Materials & Processes magazine, the limestone captures the sulfur oxides as they are formed, while the low burning temperature minimizes the formation of nitrogen oxides.
The fuel and limestone particles are recycled over and over back to the process, which results in high efficiency for burning the fuel, capturing pollutants, and for transferring the fuel’s heat energy into high quality steam to produce power.
Due to the vigorous mixing, long burning time, and low temperature of the combustion process, CFBs are fuel flexible, which means they can cleanly burn traditional coal fuels, as well as “carbon neutral” biomass and waste fuels. This ability to cleanly burn virtually any combustible material greatly surpasses the fuel limitation of conventional combustion processes.
Unlike conventional steam generators, CFBs capture and control harmful pollutants during the burning process and do not need to rely on add-on pollution control equipment. In addition, Foster Wheeler Power Group, Clinton, N.J., has applied highly efficient vertical-tube, supercritical steam technology to their utility-scale CFB designs. Supercritical steam enables more of the fuel’s energy to be transferred to the steam. This improves power plant efficiency, reducing the amount of fuel needed for electricity production and further reducing emissions.
Due to its ability to burn carbon-neutral fuels such as biomass along with coal, CFB technology offers a unique solution to the CO2 issue. Biomass is considered carbon neutral since it absorbs and stores carbon from the atmosphere during its growth cycle through the natural photosynthesis process. When biomass is burned, it releases the same carbon back to the atmosphere, resulting in nearly zero net carbon emitted to the atmosphere. However, due to the world’s limited and undeveloped biomass supply chain, existing biomass power plants are limited to about 25 to 50 MWe in size. The plant’s small scale, coupled with its fuel supply limitation, translates into electricity costing about 20 to 30% more than that from conventional fossil power plants.
Again, the CFB offers a solution. Due to its fuel flexibility, a large scale (300 MWe or larger) CFB power plant can be built to burn a combination of coal and several types of biomass. This solution captures both the environmental benefit of reducing CO2 emissions, and the economic benefit of providing affordable electricity. It is also flexible enough to utilize more biomass when it is available, or fall back on coal when it is not. This concept can produce a substantial reduction in CO2 emissions.
The entire article, written by Robert Giglio and Justin Wehrenberg of the Foster Wheeler Power Group, Clinton, N.J., was published originally in the May 2009 issue of Advanced Materials & Processes magazine and may be accessed free of charge at www.asminternational.org/amp.
Rego Giovanetti | Newswise Science News
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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