Dear Stuart Basically, a "Gasifier + IC engine" is cheaper than a "Boiler + Turbine (or steam engine)".
Turbines must have superheated steam, to enable maximum expansion of the steam, without having droplet condensation that can be a serious cause of turbine blade erosion. erosion in a steam engine is not a problem, even with saturated steam. However, the steam engine efficiency with low pressure saturated steam is dreadful. Higher pressures and superheat would considerably improve the efficiency of steam engines. Then there is the safety hazard associated with steam. Safety is not a problem with competent operators, but competent operators are expensive to hire. Additionally, there are many Government regulations connected to steam boilers and their operation, because of many fatalities in the past, as a result of poor boiler design or inadequately qualified Operators. With woodgas, there are indeed safety hazards, but they are much smaller than with steam. The main safety hazard with wood gas is the poisonous CO, but with appropriate system design and ventilation, this hazard is small. Additionally, if there is a serious failure with woodgas, it will not be as dramatic and physically devastating as would be a steam boiler explosion. So.... it is worth the bother, especially for smaller installations, to go with woodgas rather than steam boilers, and to take extra steps to clean it adequately. Best wishes, Kevin ----- Original Message ----- From: stuart mather To: stuart mather ; Discussion of biomass pyrolysis and gasification Sent: Thursday, January 31, 2013 11:07 PM Subject: Re: [Gasification] mycoremediation of tarry water Ok, steam turbines under 250 hp aren't efficient and a turbine needs super heated steam. But a reciprocating steam engine is efficient and doesn't need superheated steam, so aren't these better than trying to deal with tar in an internal combustion engine? Stuart. ------------------------------------------------------------------------------ From: stuart mather <[email protected]> To: Discussion of biomass pyrolysis and gasification <[email protected]> Sent: Friday, 1 February 2013 12:21 PM Subject: Re: [Gasification] mycoremediation of tarry water I'm just curious why syngas is ever deliberately burnt in an internal combustion engine in a deliberate setup when surely it would completely sidestep the tar/acids corrosion/disposal issue if the heat was just used to power a steam turbine driven generator? Sorry if it's a daft question. Stuart. ------------------------------------------------------------------------------ From: Robert Fairchild <[email protected]> To: Discussion of biomass pyrolysis and gasification <[email protected]> Sent: Friday, 1 February 2013 11:40 AM Subject: Re: [Gasification] mycoremediation of tarry water This might be a job for mushrooms. Really. Filter the water through straw or woodchips then innoculate with the appropriate fungus. It's known as mycoremediation. Paul Stamets is the expert. See: http://www.realitysandwich.com/mycoremediation_and_oil_spills http://www.wsdot.wa.gov/research/reports/fullreports/464.1.pdf Bob --- On Thu, 1/31/13, [email protected] <[email protected]> wrote: From: [email protected] <[email protected]> Subject: Re: [Gasification] Gasification Digest, Vol 29, Issue 7: scrubber water To: [email protected] Date: Thursday, January 31, 2013, 8:15 PM And some of the gasifiers in India simply dump it in ponds. One very well funded group set up large tanks ala biodigesters, that didn't work. This is the same group that spent $200 mm on an Australian MSW to power gasifier that was scrapped. It is not acceptable to dump the produced water in any normal waste water treatment system. Even in "clean" gasifier gas the moisture content going to the engine will bring organic acids and other compounds that will reduce the lifetime and the power output of the engine. There are effective water treatment systems available, and after years of trying a variety of options, we have landed on ones that work well and are relatively inexpensive to construct and operate. If you look at the cost of a coal gasifier water treatment plant, it is a significant investment. Sincerely, Leland T. "Tom" Taylor Thermogenics Inc. -----Original Message----- From: David Coote <[email protected]> To: gasification <[email protected]> Sent: Thu, Jan 31, 2013 5:38 pm Subject: Re: [Gasification] Gasification Digest, Vol 29, Issue 7: scrubber water How were they handling the scrubber water, Tom? A colleague visited a reasonable size gasifier in Europe where the water was stored in a tank. Once this tank was full their immediate option was to install another tank. Not ideal! Waste disposal is becoming increasingly expensive in Australia. This would increase the cost of the power. Regards David On 1/02/2013 7:00 AM, [email protected] wrote: > ------------------------------ Message: 20 Date: Thu, 31 Jan 2013 > 09:32:11 -0800 From: "Tom Miles" <[email protected]> To: "'Discussion > of biomass pyrolysis and gasification'" > <[email protected]> Subject: Re: [Gasification] > Power Pallet Message-ID: <[email protected]> > Content-Type: text/plain; charset="us-ascii" >> >yes, but remember that all that run these fuels to date are doing so by >> > tolerating a dirty gas non tar solving reactor, and fighting the tar problem > in the filtering. on the low tech end this is nearly always a water > scrubbing system, which really just>moves the toxic problem somewhere else, > and actual real world running is highly unattractive. yes, it will work for > the demo, but the ongoing issues with the bongwater cofferdam challenges > health, regulatory and general pleasurable>concerns. > > Not so fast. You can't write off "tar making" gasifiers completely. While > your observation may be true for hundreds of low cost gasifiers now in use, > in the last five years I have seen three small scale gas cleaning systems > using wet scrubbers that would pass California air quality and safety > regulations. One is produced commercially and was demonstrated at the 300 > kWe scale. Another was demonstrated at 300 KWe and used on a 1 MWe system. > One was demonstrated on a 100 kWe downdraft gasifier generating 100 kWe from > grass seed screenings. I know of another two in development for the 40 kWe > scale. (I also know of at least one that has failed miserably.) > > Tar making gasifiers may be a solution for some very difficult but abundant > fuel like rice husks and agricultural residues if the tars can be managed > and destroyed acceptably. > > Tom > _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ -----Inline Attachment Follows----- _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ ------------------------------------------------------------------------------ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
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