[Gasification] Dioxins ...was Clean air ..

[James Joyce]

Leland, regarding costs. I have had two scenarios described to me, one where the sample device is provided and I take the sample (therefore up to me to make that representative) and one where a technician comes in to collect the sample. I believe the $3000 applies to the first case ... ie. sampling is an additional cost.

If you are referring to on-line or at-line GS-MS or Gel chromatography I am interested to hear about experiences with these techniques. Our plant operators are not qualified instrument techs or lab techs ... which means at best the devices would get a check over on a monthly basis during scheduled plant visits.

My interest in the bag filter was with respect to particulates. This relates to dioxin in that they tend to be adsorbed onto the particulates (although perhaps more so at <300 deg C than 600 deg C), so it is one way to remove dioxins and their precursors if they are present. Some plants I understand actually inject fine carbon into their flue gas for this very purpose.

Kevin, on your comments about Chlorine and copper, I have been maintaining a watching brief for some time on the topic and from what I understand Chlorine levels are in fact poorly correlated with Dioxin emissions, arguably because the chlorine levels in most feedstocks, even at ppm levels are many many times the quantity needed to make the tiny amounts of Dioxins that regulators are checking for.  I read a very good review of the science just last week. If anyone wants the reference I could dig it out next week. The review of a looked critically at a variety of data on Dioxin formation and control. My interpretation of the their conclusions is that Dioxin emissions from pyrolysis, gasification and combustion processes are:

(a) Very poorly correlated with Chlorine levels, with the exception of a few industrial chemicals (not biomass)

(b) Strongly correlated to completion of combustion and the residence time of flue gases between 200 - 400 deg C (the desired residence times in this range were less than 1.6 seconds ...which perhaps does not bode well for torrefaction ! ... and hot running electrostatic precipitators)

(c) Catalysed by copper and copper compounds .. which in turn are inhibited by the presence of sulphur.

(d) Sometimes dictated by the dioxin content of the incoming feedstock rather than formation in the process

If anyone has done Dioxin measurements on flue gases from thermal processing of biomass I certainly would be interested in their experiences.

Regards,

James

------------------------------
Date: Sat, 28 Jun 2014 05:50:23 -0400 (EDT)
From: linvent at aol.com
To: gasification at lists.bioenergylists.org
Subject: Re: [Gasification] Clean Air Regulation requirements imposed
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 James,
	The price you stated for a dioxin test is just the analysis and does not include the technician's travel time, set up time and sampling time, per US costs.?
	There is a method of on-stream continuous measurement that will give analysis of all of the compounds presented in the standard you referenced that will also include fixed gases to almost any molecular weight.?
	I can't see how any bag or filter can be used to clean the gas.?
	
Sincerely,
Leland T. "Tom" Taylor
Thermogenics Inc.?


Date: Sat, 28 Jun 2014 09:22:55 -0300
From: "Kevin" <kchisholm at ca.inter.net>
To: "Discussion of biomass pyrolysis and gasification"
	<gasification at lists.bioenergylists.org>
Subject: Re: [Gasification] Clean Air Regulation requirements imposed
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	reply-type=original

Dear James

It is my understanding that if Chlorine is present in a "biomass pyrolysis 
situation", the presence of dioxins is virtually guaranteed.

For example, if yak or cattle dung, chicken or feedlot manure, or salt water 
driftwood are pyrolysed or partially burned, there will be dioxins in the 
resulting pyrolysis gases or smoke.

QUANTITATIVE testing for dioxins could be very expensive, as you suggest. 
However, QUALITATIVE testing can be very low cost. Simply heat a copper wire 
red hot in the presence of the gas being tested for dioxins, when chlorine 
gas or chlorofluorocarbon refrigerants are known to be absent. If dioxins 
are present, the flame turns green or blue-green.

Best wishes,

Kevin