[Gasification] Hazardous classification of MSW, plasma gasification thermodynamics

[Tom Miles]

Not all plasma systems are identical so it's not necessarily correct to think of plasma gasification as an environment of intense heat. Systems like those promoted by AlterNRG/Westinghouse maintain intense temperatures in the ash bed but the gases must travel up through a cooler pile of pyrolyzing fuel in which many of the inorganic components would condense. The top of the fuel pile looks like any other updraft gasifier except that by using the plasma to maintain the process (3% of heat input) you use less air. There are waste plasma gasifier coupled to boilers in Japan. 

Tom



-----Original Message-----
From: gasification-bounces at lists.bioenergylists.org [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of linvent at aol.com
Sent: Sunday, February 12, 2012 7:45 AM
To: gasification at lists.bioenergylists.org
Subject: Re: [Gasification] Hazardous classification of MSW, plasma gasification thermodynamics

GAsification produces an ash where the RCRA hazardous metals are bound and inert,  and pass US EPA TCLP leachate test which means that it can be put into landfill. I am not sure how MSW can be classed as a hazardous waste as per your language Peter. Otherwise normal landfills would also accept hazardous waste. Metals volatilized in a normal gasifier are condensed in the lower temperature section of the gas processing. In plasma gasification they would coat any nearby cooler surface very rapidly, leading to potential blockage in short order. The amount of energy put into plasma gasification is a waste of energy as all of the desired reactions occur at much lower temperature and it makes no thermodynamic reason to go above those temperatures. Ash vitrification in plasma is supposedly better, but the lower temperature and hydrogen environment of a regular gasifier produce a stable TCLP ash anyhow.
There are direct methods of measuring metals in a gas stream. There is an interesting study where the metal balance in a gasifier is attempted to be determined but couldn't. More went in  than came out and where the difference occurred was never determined.
Sincerely,
Leland T. "Tom" Taylor
President
Thermogenics Inc.

-----Original Message-----
From: jonathan <jonathan at bmpconsultants.com>
To: Discussion of biomass pyrolysis and gasification <gasification at lists.bioenergylists.org>
Sent: Sat, Feb 11, 2012 7:39 pm
Subject: Re: [Gasification] Steam Turbines

We can provide custom turbines; if you will forward your requirements I'll provide you with a quote.

Thanks,


Jonathan

On Sat, Feb 11, 2012 at 3:58 PM, Peter & Kerry <realpowersystems at gmail.com> wrote:
Hi Liran,

The 2 second combustion requirement is an Interesting and slightly disturbing prescriptive regulator response (that narrows gas use options), is somebody in authority just guessing and being cautious or is it based around actual gas analysis results from your plasma gasification system?

What potential constituents in the gas stream are these requirements aimed at?

In regard our own experience with gasifying hazardous waste (sewerage sludge with potential heavy metal contaminants, particularly mercury &
cadmium) the client at the time for this (a large public authority) would not pay for direct emissions testing covering these so we paid out of our own pockets for an indirect "indicator" measurement, getting a ultimate analysis of the raw feed stock and the same test on the ash collected from the test run, then had a industrial chemist review the results. This showed the metals identified in the original analysis were captured within the ash in equivalent amounts relative to the mass reduction from the original sample (so didn't travel out with the gas).

Is this a problem with Plasma gasification? Are such contaminants mobilised in the gas instead?

We are currently engaged in the early stages of a formal testing project involving MSW and other hazardous wastes that will have EPA oversight and permitting for the trial. The results from this will inform pilot commercial scale system design and operating parameters in regard to emission management for our own system, so we are interested in what other regulator agencies are thinking in regard general gasification issues that might be flagged along the way.

Otherwise we would agree with Pannierselvam's question. Certainly subject to your gas meeting all the requirements for gas turbines (not just energy content) then these combined with downstream HRSG steam units using this exhaust, perhaps augmented with some  auxiliary firing if needed, could be another way to meet your regulatory requirement.

At the moment we are unaware of any commercial fuel cells that wouldn't require a high level of gas polishing and separation without quickly poisoning the cell, but also would love to hear more.

Regards,
Peter

Peter Davies
Real Power Systems Pty Ltd
Australia


Steam Turbines

Liran Dor liran at eer-pgm.com
Sat Feb 11 13:26:27 CST 2012
Previous message: [Gasification] Steam Turbines Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Dear Pannierselvam,

Thank you for your reply

The reason for the rankin cycle is that due to the fact we are treating hazardous waste the environmental regulation dictate we combust the gas in a chamber with a 2 second residence time.

I do like your approach for the MSW application we are working on and would like to hear more about it.

Thanks

Liran


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