[Stoves] [MHAtech] Re: Top lit updraft combustors

[Crispin Pemberton-Pigott]

Dear Tom

I have an interesting conversation with my gasifier friend about that and I posed the question as to whether or not the 20-22% ‘limit’ is in fact the fixed carbon content of the biomass.

If the biomass is heated above 550 there will be no tarry gases emerging from then on. The difference between the carbon yield at that point and the fixed carbon content is not much. In order for char to be produced in the 35-40% range it would have to include some tars that distilled at temperatures above the process temp involved.

Do I have that correct?
Thanks
Crispin


From: Tom Miles [mailto:tmiles at trmiles.com]
Sent: 19-Dec-17 06:16
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Cc: Ronal W. Larson <rongretlarson at comcast.net>; Law, Steven (MOECC) <Steven.Law at ontario.ca>; Crispin Pemberton-Pigott <crispinpigott at outlook.com>; Sauve, Terrence (OMAFRA) <Terrence.Sauve at ontario.ca>
Subject: Re: [Stoves] [MHAtech] Re: Top lit updraft combustors

Similar Gasifiers get 15%-20% yields. I would question 25% or more.
T R Miles Technical Consultants Inc.
tmiles at trmiles.com<mailto:tmiles at trmiles.com>
Sent from mobile.

On Dec 18, 2017, at 6:50 PM, Norbert Senf <norbert.senf at gmail.com<mailto:norbert.senf at gmail.com>> wrote:
On Mon, Dec 18, 2017 at 6:22 PM, Ronal W. Larson <rongretlarson at comcast.net<mailto:rongretlarson at comcast.net>> wrote:
[RWL:  I sometimes hear of reverse flow in chimneys.  Not  to worry in your systems?

It can be an issue with cold starts, but is not a safety concern because there will be noxious smoke, which is obvious. There are various workarounds/fixes for this
In normal operation, the heater is warm, and will keep powering the chimney draft long after the fire is out until all the heat is sucked out of the mass.
During the charcoal phase, when the thermal mass has been heated, chimney draft is never an issue.
This is quite the opposite of "airtight" stoves that you fill with wood and then turn down for an overnight burn. During the middle-of-the-night charcoal phase, draft can get low and house depressurization can cause a reversal and CO spillage.

[RWL:  No - medium .  I almost never varied a percentage point from 25% by weight (multiply by about 30/18 to get energy).  But we hear 30% by weight sometimes (low temperature char).

Thanks, interesting to know what a good number for yield would be ...............N

--
Norbert Senf
Masonry Stove Builders
25 Brouse Road, RR 5
Shawville Québec J0X 2Y0
819.647.5092
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