[Gasification] Fwd: RE: Whole log pyrolysis for char production was Re: W...

Fri Jan 3 00:05:51 CST 2014

Regarding the reflected heat from the refractory: If you were to travel on  
the footplate of a steam locomotive at full regulator, you might observe  a 
temperature of 2,500 f in the fire box. in which there is  generally  a 
refractory (brick) arch above the grate which extends the  flame pattern and 
generally helps the secondary air entering above the grate to  insure compete 
combustion. I have observed these arches to glow bight  Yellow, the surface 
of the brickwork actually  melting with the heat. I  am certain the 
radiation has a  lot to do with complete combustion.  Would this form of radiation 
help refine "smoke" (gas) breaking it down  into short chain Molecules?

GF

In a message dated 1/2/2014 3:35:33 A.M. Eastern Standard Time,  
rex at whitfieldfarm.co.za writes:

Paul, 
I  designed a diesel burner for preheating a bubbling fluidised combustor 
about  12 years ago. Fortunately I took advice from an old and experienced 
engineer  who advised that we had to line the fire box with refractory. When 
questioned  why, his explanation was as follows: the diesel burns and gives 
off radiant  heat to the wall. The wall heats up and radiates heat back 
toward the flame.  The incoming radiation from the refractory is what evaporates 
and heats the  diesel so that it is able to burn nearly completely (as 
opposed to the smoky  start when the refractory is cold). I suspect that Rolf’s 
refractory does much  the same thing in that it sends radiation back into the 
log. This heating  effect is frequently underestimated as to its assistance 
with the whole  combustion process. We also use this effect in the first 
portion of wall above  the bubbling fluid bed level to provide radiation into 
the secondary air  combustion area. Above this we build a membrane wet wall 
boiler. As with Rolf,  our secondary air is aimed downward as we run the 
bubbling bed under a slight  vacuum.  
I  am looking forward to seeing Rolf’s photos. 
Rex 

From: Paul Anderson [mailto:psanders at ilstu.edu] 
Sent: 27  December 2013 04:49 PM
To: Discussion of biomass pyrolysis and  gasification; 
biochar at yahoogroups.com
Subject: [Gasification] Fwd:  RE: Whole log pyrolysis for char production 
was Re: Wood heating in the UK -  whole log gasification

Dear all,

This excellent reply below came from  Rolf.   Thank you!!

Pictures only after 6 January, but by  then I am in Africa and might not 
remember to request that Rolf send  them.  Together, we should be able to get 
this worked out.

We  definitely should have some other people replicating this and 
suggesting  solutions for char removal, etc.    And there should be some  examination 
of the pyrolyzed log concerning the char in the center verses the  char at 
the edges, and % yield (by weight).

Paul 

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD  
Email:  _psanders at ilstu.edu_ (mailto:psanders at ilstu.edu)    
Skype: paultlud      Phone: +1-309-452-7072
Website:  _www.drtlud.com_ (http://www.drtlud.com/) 

-------- Original Message --------      
Subject:    
RE: Whole log pyrolysis for char production was Re:  [Gasification] Wood 
heating in the UK - whole log  gasification   
Date:    
Fri, 27 Dec 2013 08:50:06 +0100   
From:    
energiesnaturals _<energiesnaturals at gmx.de>_ 
(mailto:energiesnaturals at gmx.de)    
Reply-To:    
energiesnaturals _<energiesnaturals at gmx.de>_ 
(mailto:energiesnaturals at gmx.de)    
To:    
_psanders at ilstu.edu_ (mailto:psanders at ilstu.edu)  

Hallo Paul,

Thanks for your interest in our living room  stove/boiler!

Because that's what it is.

I build this one and quite a few more many years ago in the  pre pellet 
area.

It is not really a big thing but just what i said in my 1.  Description for 
Ken.

An airtight firebox with controlled primary and secondary  air, both 
preheated by the non insulated air and water xchanger above the  burning chamber.

The primary 60% is used to regulate the gasification (  remember it is an 
all night heater on one log) and the secondary actually  burns the 
develloping gas.

The escape hole is central in the dome. The admission pipes  of 2.air are 
offset and aimed at a 30 deg.downwards to create a turbulance and  thus allow 
for a quite complete combustion before the gas leaves the hot area.  We use 
mainly white pine, p.halepensis, airdried or so-so and we clean the  
conducts every 2. year or so, it burns so clean.

After 1-3 h, depending on the log, you can find the  remaining carbon in 
more or less the shape of the log.

We do not use the char at present, cause it would be a mess  to take it out 
inside the living room...,but if we put in the last log around  midnight 
and close all the 1. And most of the 2nd air once it is lit, we are  left with 
a good bed of embers for toasting our breakfast  bread.

If our aim was to produce char , i should have incorporated  a movable 
floor( no grate) to discharge it into a cooling device below or yes  a grate and 
create a repeating cycle without the need to light the batch every  time.

(Un-)luckily i cannot provide any pictures right now,  because we spend a 
wonderful holydays at our doughter's in  Budapest.

But if you want some, tell me after the 6th next  year.

B.r.

Rolf

Paul Anderson _<psanders at ilstu.edu>_ (mailto:psanders at ilstu.edu)   
escribió: 

Dear Rolf,    (and hello to Greg!!)

I  am very interested in your method of whole log gasification.   In  
particular, I am interested in your statement that the pyrolysis occurs first  
(or mostly first is fine), leaving the char to either be consumed (char  
gasified) or removed.    My interest is in removing / saving  the char for a 
variety of other purposes, including possible use as biochar.  (I am interested 
in using the heat, but that can be treated as a  separate topic.)  

Therefore, I am sending this message to the  Biochar Listserv.   But 
because relatively few people subscribe to  both lists, I (and Ron Larson and Tom 
Miles) will relay your reply to the  Biochar List.   Eventually these 
messages could be taken off of the  Gasification List and just continued with the 
Biochar list, but let's see what  develops.

Could you please provide some:
some   photos,
construction plans if available, 
and some data on what  percentage of char is yielded from the dry weight of 
the feedstock  logs.

I am content with using cordwood that is smaller than the 45 cm  diameter 
that you mention, so any comments about the good or bad of using 10  cm or 25 
cm diameter feedstock would be appreciated.

Although as you  say it is "a tad late", I will count your message and 
replies among my most  treasured presents received this year for  Christmas!!

Paul

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD  
Email:  _psanders at ilstu.edu_ (mailto:psanders at ilstu.edu)    
Skype: paultlud      Phone: +1-309-452-7072
Website:  _www.drtlud.com_ (http://www.drtlud.com/) 
On 12/26/2013 5:16 PM, energiesnaturals  wrote:

Merry Christmas Ken and list ( I am aware that I am a tad  late)

One way to burn whole logs like we do (45cm across x 55  cm long) in an 
efficient way is to build a well closed ,dome shaped burning  chamber out of 15 
cm fire brick and have individually regulated, preheated  primary and 
2,dary air , at least 2 pipes either side.

You build up afire with kindling as you describe it and  after 15 min you 
can add  an entire log of pitchy pine and it will  first gasify very nicely 
and than burn the charcoal if you  want.

The secret is to keep the  walls of the combustion  chamber warm and do not 
use them as heat xchangers!

You build a convenient xchanger above it and use the hot  exhaust gas. 
Build it large enough to reduce the exhaust temp to 90 deg C or  less and you 
will be way above 50 % eff. Ours has been working for 20+ years  and is still 
doing fine with 2 mm black steel pipes.

We never cut anything below 55 cm long and never split  anything below 45 
cm, believe me or come and see!

Cheers and a happy new year

Rolf

Enviado desde Samsung tablet

Ken Boak _<ken.boak at gmail.com>_ (mailto:ken.boak at gmail.com)   escribió: 

Greg  

Thanks for sharing.

I want to try a few ideas for myself to see if this is  indeed possible on 
the small split logs I can produce  locally.

Our heating needs, and indeed modest on account of the  mild climate here, 
but I would like to find an efficient solution for all  the thousands of 
acres of neglected coppiced hardwood.  Cast iron  victorian stoves may be 
quaint, but I am sure there are ways to improve the  overall efficiency with 
radical redesign.

The main burner/heat exchanger on our 24kW gas boiler is  no bigger than a 
gallon paint tin.  Perhaps there is design lesson to  be learned here

Anything to reduce mechanical handling and processing of  wood fuels has to 
be a step in the right direction

Happy New Year 

Ken

On 26 December 2013 19:22, Greg Manning <_a31ford at gmail.com_ 
(mailto:a31ford at gmail.com) > wrote: 

Greetings Ken, and list members.  

Ken, I'm going to point you to a video of the "underside"  of a whole log 
(or split) "cordwood as we call it here" stove that is a  downdraft gasifier.

I can speak at length privately, however only somewhat on  list, as this is 
a proprietary design. 

Here's the link to the video:

http://youtu.be/DNYCfgEdYpg

Greg Manning

On Thu, Dec 26, 2013 at 12:59 PM, Ken Boak <_ken.boak at gmail.com_ 
(mailto:ken.boak at gmail.com) > wrote:

Happy Christmas to the gasification  list.

At this time of year, during the festive holiday  season, I get a bit more 
time to manage the running of our woodstove, as  it rapidly warms the room 
and produces a cheery  effect.

Our property is fairly conventionally heated by natural  gas, but a few 
years back, I took the decision to invest in a woodstove  with back-boiler, to 
provide an alternative or back-up to the gas fired  system.

The woodstove has a flat steel tank at the rear, the  "back boilerr", in 
place of a couple of the firebricks lining.  This  circulates heated water 
entirely by the thermosyphon principle to a  radiator located in the 
bedroom/workroom directly above the stove. So in  effect the stove heats the living 
room/kitchen area  directly, and  the room upstairs by circulating hot water.

No electricity is required for circulation, and if  worse-case we had an 
extended power outage, this stove would provide heat  and comfort in the two 
main occupied areas of the house. Stoking it and  attending it is often more 
interesting than what is being shown on  TV!

With a few days off work, I have had time to monitor  the stove and make 
some assessments of its overall performance. Its a  fairly traditional stove,  
a rectangular box,, made from bolted  together cast iron panels and partly 
lined with firebrick. It's described  as a multifuel stove - having been 
supplied with a cast iron removable  grate for burning coal - which is not used 
when burning wood. It's  approximately 24" wide, 12" deep and 18" tall.

In the UK, a common size for firewood logs, intended  for the domestic 
woodstove is about 10" (254mm) long, and equal to a 1/4  round taken from a limb 
that may have been 5 or 6" in diameter.  The  reason for this is that there 
is a lot of coppiced hardwood, which has  become mis-managed in the last 20 
years, so there are a lot of trees with  6" diameter shoots.  The 
popularity of the "firewood processor"  machine, means that a lot of this wood is now 
coming on the market as  domestic firewood, and sold to suburbanites at 
vastly inflated prices  (about $0.50 per kilo).

I am burning a mixture of kiln dried Silver Birch, and  air dried other 
species which includes ash, oak and sweet chestnut. The  silver birch splits 
well and makes excellent kindling.  One log is  split into 8 or 10 kindling 
sticks and these are built into a pyramid  around 2 or 3 sheets of scrunched 
up newspaper. Lighting is quick and easy  - as the birch is kiln dried, and 
within 5 minutes you will have a roaring  fire and the larger logs can be 
added.

The logs have an average weight of approximately 1 kg.  I have found that a 
normal burn rate of these is two per hour.  I burn two at a time, and each 
hour, add a further two to the  burning char bed from the previous logs.  
With firewood having a  calorific value of approximately 4kWh/kg - I estimate 
the fuel input is in  the order of 8 to 10kW.

Of course, with a traditional stove, so much of the  heat energy is lost up 
the chimney, and goes to create the draft.  The efficiency of the stove, 
might be in the region of 50% -  somewhat better than the open wood fire.  It 
occurred to me that by  way of a 2 stage gasification process, it would be 
possible to increase  the overall system efficiency, resulting in less wood 
consumption, or more  heat output per log.

This leads to a question - is it possible to design a  gasifier aimed at 
handling whole log gasification - where a log is 10"  long and no more than 6" 
across?  Can you recreate the temperatures,  turbulence and reactants, 
found within the combustion zone of the  woodstove, and use this to thermally 
process a single firewood log, at the  rate of one every 30 minutes or so?

I've had some ideas on how this can be done,  effectively using a length of 
6" diameter stovepipe/fluepipe to make a  compact gasifier.  Logs would be 
loaded in from the top, and the  length of the pipe chosen to perhaps hold 4 
logs at any time - about 1m  (40") tall.  The bottom log would sit in the 
combustion zone -  so the end of this log is constantly under the action of 
the air nozzles.  The logs above are subjected to the elevated temperatures 
and begin to  pyrolise, char and split on their descent down the  tube.

Beneath the combustion zone would be a fairly  conventional hearth, and 
reduction zone, with the char supported by a  grate below that. For an overall 
idea of the system - think of HS Mukundas  open top gasifier. 

Use of twin-wall stainless flue pipe would allow the  air to be pre-heated 
in the outer annulus - adding to the overall  efficiency.  The hot syn-gas 
could be burned in whatever appropriate  burner geometry deemed necessary for 
either radiant space heating or water  heating with a suitable heat 
exchanger coil.

I hope to try to build a prototype of this over the  next 10 days (a 
working gasification holiday?)  and to see whether a  log can be reduced in this 
manner.  If all that is needed is heat,  then the restrictions to produce a 
tar free gas need not apply. If one can  use whole logs, without having to 
resort to woodchip - then this will be a  considerable saving in mechanical 
handling and wood  processing.

At the end of the day - this gasifying stove needs to  be as simple to 
operate as the existing woodstove.  Reloading with a  couple of logs each hour, 
and no sophisticated need for fan- forced draft  or electricity to operate. 
Draft would come from the chimney as per now -  about 25 to 30 feet, 6" 
diameter.

If anyone has experience of something similar - please  let me know.

Happy Holidays

Ken

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