Archive for February, 2014
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February 25th, 2014

Environmental regulations can, of course, impact the development and implementation of green technologies. This can happen on an industry level, for example, when automobile fuel efficiency technology is improved in response to rising CAFE standards.
It can also happen on a smaller scale and affect one company at a time, such as MaxWest Environmental Systems (Maxwest), which has developed gasification technology to break down sewage sludge.
The U.S. Environmental Protection Agency (EPA) recently ruled that MaxWest’s patented gasifier is not an incinerator and therefore will not be regulated as such. According to the company, this means the technology can be developed and implemented at a lower cost to municipalities (see the press release here).
MaxWest owns at least one patent and one published patent application relating to its gasification technology. Â U.S. Application Publication No. 2013/0195727 (‘727 Application) is entitled “Fluidized bed biogasifier and method for gasifying biosolids” and directed to a gasifier and methods of gasifying biosolids obtained from sewage sludge.
A fluid bed gasifier (200) includes a bubbling reactor bed section (204) which receives sewage sludge through feed inlets (201) and flue gas through a flue gas inlet (203). Â The gasifier has a freeboard section (205) between the reactor bed section (204) and the outlet (210) of the gasifier.

A cyclone separator (207) separates material exhausted from the fluidized bed reactor into clean producer gas for recovery and ash for disposal. Â An oxygen monitor (209) may be used to help control oxygen levels in the gasification process together with a producer gas control (208), which monitors oxygen and carbon monoxide levels in the producer gas.
It appears that the control of oxygen levels was critical to the EPA ruling. Â According to the ‘727 Application, the biogasification process occurs in an “oxygen starved environment” which prevents combustion. Â Because there is no combustion, the gasifier is not classified as an incinerator.
An older gasifier technology is described and claimed in MaxWest’s U.S. Patent No. 7,793,601 (‘601 Patent), issued in 2010 from an application filed back in 2005. Â The ‘601 Patent is entitled “Side feed/centre ash dump system” and directed to an apparatus for gasifying solid fuel where the biomass feed material is introduced into the primary oxidation chamber (400) through in opening (408) in the side of a wall (402) or in the floor of the chamber (400).

The wall (402) has multiple layers, and the innermost layer (405) is made of a high-temperature refractory material capable of withstanding elevated temperatures. Â According to the ‘601 Patent, the wall (402) is therefore capable of allowing oxidation of biomass while maintaining a tolerable skin temperature on the outside of the wall.
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Readers of this blog know that I have a soft spot for patent PR, particularly green patent PR (see, e.g., here and here). Â So I’m always interested in covering announcements by green tech companies about their patents.
Aphios, a Massachusetts company that develops technology for cellulosic biomass conversion, recently put out a press release announcing the grant of U.S. Patent No. 8,540,847Â (‘847 Patent).
Entitled “Methods and apparatus for processing cellulosic biomass,” the ‘847 Patent is directed to methods and apparatus for making ethanol or other biofuels using what Aphios calls its Aosic process.
The apparatus (11) described and claimed in the patent comprises a first vessel (13) for receiving cellulosic biomass and conveying means (15) in fluid communication with the first vessel (13). Â The apparatus (11) also comprises supercritical, critical, or near critical fluid means (17), which includes a source of gas, such as gas tank (41), holding carbon dioxide pressurized to form supercritical, critical, or near critical fluid.
The fluid means (17) is in fluid communication with conveying means (15) via conduit (31). Â A pump (47) is connected to a heat exchanger (55), which controls the temperature of the supercritical, critical, or near critical fluid.

The cellulosic biomass is loaded into the first vessel (13) and becomes laden with the supercritical, critical, or near critical fluid. Discharge means (21) is in fluid communication with the conveying means (15) for receiving cellulosic biomass laden with the supercritical, critical, or near critical gas and discharging the gas to form a disrupted cellulosic biomass.
A second vessel assembly (23) may include a hydrolysis vessel (23a) and a fermentation vessel (23b) for further processing of the cellulosic biomass. Â Discharge means (21), including a discharge pipe (71) is connected to a turbine (73), which captures the kinetic energy of the expanding gas. Â The turbine (73) is coupled to an electric generator to recover and recycle energy from the process.
According to the press release, contacting the cellulosic biomass with the supercritical, critical, or near critical fluid or gas improves the process by separating the fibers of the biomass:
In the Aosic process, biomass is contacted with SuperFluids such as carbon dioxide with or without small quantities of polar solvents such as ethanol, both sourced from the downstream fermentation process. Pressure is released and fibers are made more accessible to enzymes as a result of expansive forces of SuperFluids (about 10 times those of steam explosion) and carbonic acid hydrolysis.
The ‘847 Patent says the process provides biomass recovery yields between 95 and 99 percent. Â Thanks to Biofuels Digest, from whence I picked up the Aphios news.