Thursday, August 5, 2010
Thursday, March 6, 2008
update on why I have not been posting
OK, I realize I have been completely remiss in my obligations to post at least somewhat regularly. So I apologize to all of my loyal readers who have been anxiously awaiting my next entry.
Ha!
I'm the only one who ever reads this thing.
At any rate, I have a good excuse, I have been so damn busy with school work that I barely have time for anything.
But never fear. Within the next two weeks I will be completing the first major deliverable for my plasma-gasification project. It is the business case and it will be around 12 pages long and I will post it. Probably won't do anything on the blog until then though.
Ha!
I'm the only one who ever reads this thing.
At any rate, I have a good excuse, I have been so damn busy with school work that I barely have time for anything.
But never fear. Within the next two weeks I will be completing the first major deliverable for my plasma-gasification project. It is the business case and it will be around 12 pages long and I will post it. Probably won't do anything on the blog until then though.
Tuesday, January 29, 2008
Getting Organized
OK,
So I realize that my blog is a bit unwieldy so far, too much text, not enough graphics, and I am rambling in general.
I am working on some technical solutions to index my collection of documents about gasification. I have at least 1 GB of .pdf files, a lot of which are federal government reports on coal and biomass gasification. By indexing these documents I will be able to search them more easily and hopefully improve my writing by being more succinct and to the point.
Ideally I would expand this whole effort into a website and host all the doc's on the site and have a public accessible library. But one thing at a time. I barely can find the time to blog, much less build an entire site right now.
So I realize that my blog is a bit unwieldy so far, too much text, not enough graphics, and I am rambling in general.
I am working on some technical solutions to index my collection of documents about gasification. I have at least 1 GB of .pdf files, a lot of which are federal government reports on coal and biomass gasification. By indexing these documents I will be able to search them more easily and hopefully improve my writing by being more succinct and to the point.
Ideally I would expand this whole effort into a website and host all the doc's on the site and have a public accessible library. But one thing at a time. I barely can find the time to blog, much less build an entire site right now.
Friday, January 25, 2008
Plasma-Arc Gasification
Plasma-Arc Gasification is a unique form of gasification that utilizes plasma torches to generate the highest temperatures of any type of gasifier. Plasma is an ionized gas that forms from high currents of electricity passing through the air across two electrodes. Plasma is sometimes called "the fourth state of matter" after solid, liquid, and gas. We see plasma in nature in the form of lightning bolts and also on the surface of the sun. The fundamental advantage of utilizing plasma is that it generates much higher temperatures than other technologies, and since it is electrically powered it can be fired up at the flip of a switch (a pretty big switch!) and attain operating temps almost immediately, and be shut down just as quickly. Plasma torches can generate heat up to 10,000 degrees.
Plasma gasification utilizes two primary techniques, the transferred torch and the non-transferred torch. The non-transferred torch has the electrodes inside the torch body and on the outside of the gasification reactor, air is blown through the torch across the plasma arc and into the gasifier. This it the type of system developed by Westinghouse-Plasma Corp which is the world leader today in gasifying MSW. I will detail the Westinghouse technology quite a bit in my blog.
A transferred torch places the electrodes inside the reactor and the arc is made inside the reactor. Proponents of this technique claim better heat transfer and electrical power efficiency, the downside may be greater wear on the torch because of the corrosive nature of the gases. Transferred torches are used in electric arc furnaces in the steel making industry. Heat also needs to be balanced between making sure there is enough to effectively break down all of your feed and the resulting tars while at the same time protecting the interior of your reactor and its refractory lining. Uncontrolled heats will damage the reactor.
Plasma torches have been used for many years to dispose of hazardous wastes and to melt foundry wastes and incinerator ashes. The military has also used the technology to destroy chemical weapons.
Plasma gasification utilizes two primary techniques, the transferred torch and the non-transferred torch. The non-transferred torch has the electrodes inside the torch body and on the outside of the gasification reactor, air is blown through the torch across the plasma arc and into the gasifier. This it the type of system developed by Westinghouse-Plasma Corp which is the world leader today in gasifying MSW. I will detail the Westinghouse technology quite a bit in my blog.
A transferred torch places the electrodes inside the reactor and the arc is made inside the reactor. Proponents of this technique claim better heat transfer and electrical power efficiency, the downside may be greater wear on the torch because of the corrosive nature of the gases. Transferred torches are used in electric arc furnaces in the steel making industry. Heat also needs to be balanced between making sure there is enough to effectively break down all of your feed and the resulting tars while at the same time protecting the interior of your reactor and its refractory lining. Uncontrolled heats will damage the reactor.
Plasma torches have been used for many years to dispose of hazardous wastes and to melt foundry wastes and incinerator ashes. The military has also used the technology to destroy chemical weapons.
high temperature and slag
There are endless varieties of gasifiers that have been produced over the years. Gasification is very much an art and the equipment is tailored to the feedstocks that are put into it. Most gasifiers have been used for either coal or biomass and have been optimized for those purposes. Generally speaking coal gasification is done in very large industrial facilities while biomass gasification is done on a much smaller scale, and is often done by hobbyists and tinkerers in their garage as well as in developing world countries.
I intend to do a review of gasification technologies at some point.
The challenge in gasifying garbage (municipal solid waste or MSW) is the heterogeneous nature of the materials. MSW by its nature is composed of a huge variety of materials ranging from plastics and papers to metals, glass, construction debris, and many others in varying sizes and moisture contents. Traditional gasifiers cannot handle such mixed waste. In order to reliably process MSW the gasifier needs to operate at much higher temperatures and throughputs. Basically the temperature needs to be high enough that it can reliably melt all the metals and glass that go in. Gasifiers that melt metals and ashes are called "slagging" gasifiers because the melted materials from glass, mineral, stone, and metal becomes molten fluid in the gasifier and will pour out a tap hole and be cooled. Once cooled the molt is called slag and it forms vitrified glass. The slag is very stable and in the USA must pass EPA TCLP leachability tests which test for a variety of potential toxins that may potentially leach out. Slag from high temperature gasifiers is remarakbly stable and clean. The high temperatures break down organic hazards and the glass itself seals up many other dangers such as volatile metals like mercury, lead and cadmium.
Insert details on TCLP tests.
Insert characteristics of Slag. Review New York harbor sludge.
I intend to do a review of gasification technologies at some point.
The challenge in gasifying garbage (municipal solid waste or MSW) is the heterogeneous nature of the materials. MSW by its nature is composed of a huge variety of materials ranging from plastics and papers to metals, glass, construction debris, and many others in varying sizes and moisture contents. Traditional gasifiers cannot handle such mixed waste. In order to reliably process MSW the gasifier needs to operate at much higher temperatures and throughputs. Basically the temperature needs to be high enough that it can reliably melt all the metals and glass that go in. Gasifiers that melt metals and ashes are called "slagging" gasifiers because the melted materials from glass, mineral, stone, and metal becomes molten fluid in the gasifier and will pour out a tap hole and be cooled. Once cooled the molt is called slag and it forms vitrified glass. The slag is very stable and in the USA must pass EPA TCLP leachability tests which test for a variety of potential toxins that may potentially leach out. Slag from high temperature gasifiers is remarakbly stable and clean. The high temperatures break down organic hazards and the glass itself seals up many other dangers such as volatile metals like mercury, lead and cadmium.
Insert details on TCLP tests.
Insert characteristics of Slag. Review New York harbor sludge.
Thursday, January 24, 2008
Great slideshow on gasification history
http://www.slideshare.net/ncenergy/operating-engines
-on-woodgas-by-bill-olsen/
(get the link on one line!)
Hoping to get permission to post the whole file, but in the meantime take a look at the link. Fascinating stuff, especially once you get to pictures of all the woodgas cars. Don't think too many of those would pass inspection here in the US!
-on-woodgas-by-bill-olsen/
(get the link on one line!)
Hoping to get permission to post the whole file, but in the meantime take a look at the link. Fascinating stuff, especially once you get to pictures of all the woodgas cars. Don't think too many of those would pass inspection here in the US!
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