New biochar ideas from The Warm Heart team. Bringing excellent innovations to the world.
E, Dolph, aloha kaua-
We have been developing a new type of flame cap / flame curtain (FC) biochar production unit that we think may be of interest to your readers. These are the FC Trough units, which are defined as above ground FC units with a non-square, rectangular top aspect.
The design was developed as a result of considering the easiest low tech way to pyrolyse a great variety of the feedstock types available to the small holders in developing countries, that is, a minimum amount of processing &/or transportation of the feedstock beyond the initial harvesting. Given this economy of effort/cost and the basic growth pattern of much potential feedstock, it seems the design will also be of interest to the small to medium low tech distributed biochar makers in developed regions. These are Top Fed Open Draft FC units and not to be confused with kilns since they do not fit the standard English definition of kiln.
New biochar ideas
The Warm Heart team has come up with a special type of FC Trough design which features reduced weight without sacrificing durability and without greatly increasing fabrication cost or difficulty. This is accomplished by reducing the thickness of the firebox sheet metal and laying out the base and long sides as a single rectangular panel so that the sides are simply bent up from the central base section of the panel at the desired angle (see schematic detail). The ends are inverted isosceles trapezoids congruent with the outline of the bent base and long sides. They are welded on at right angles to the base. This light weight fire box is cradled in a light weight supporting frame made of box iron (or ‘square iron’ – iron bars with a hollow square cross section). To further strengthen the unit and secure the firebox in place a ring of angle iron encircles the top of the unit with its vertical arm on the inside of the unit and its horizontal arm making the uppermost rim of the unit. Thus the firebox rim is sandwiched between the box iron cradle rim and the angle iron (see schematic detail).
Photo 1) The 3 main types of FC Troughs in the Warm Heart (WH) line.
In the foreground is a T 500, a 500 l FC biochar oven designed for 2 person carry in rough terrain. Behind to the right rear is an XLT 1k, a 4.7 m long unit of 1 m3 capacity designed specifically to minimize cutting when processing bamboo. To the left rear is a T2k a short and wide unit of 2 m3 capacity designed for transportation (singly or stacked multiple units) in a light pickup truck and carried in the field by 4 individuals.
Photo 2) The WH T500 oven – This 500 l oven trough was specifically designed for hill tribe farmers for 2 person distance carry on steep, rough, and/or forested terrain either by using a carrying pole or the alternate side handles, front & back. The extra-long handles allow for up to 8 persons to carry the unit when carrying a load. It is also small enough to be easily moved by one person on level ground in a cart or with a set of strap on wheels.
Photo 3) The original WH T2k – This is the first version of the 2 m3 LLU (large low-tech unit) trough. It was designed to sit on top of a towing skid which raised the angled sides enough to clear the wheel wells of the small pickup used for transportation. Towing in the rough local fields proved difficult and the local workers preferred to hand carry the unit. Foregoing the towing skid resulted in the sides coming in contact with the wheel wells before the bottom of the unit rested on the truck bed so the profile was made narrower at the base and taller in the standard design. The handles extending from the top of the original design made lifting the unit for ground clearance when hand carrying somewhat difficult for all but tall individuals. This would have been accentuated by the added height of the second rendition, so the handles were lowered to the sides in the standard version and lengthened so that two persons could carry in tandem at each handle for added lifting power. Also, local workers preferred to bucket or tip excess water out of the units. Consequently, the drains were seldom used and usually allowed to rust shut, so few of the other units were fitted with them to save on unit cost and fabrication effort. The man stoking the unit in the photo is a member of a 6 man team, 5 of whom cut and carry the cornstock to the unit with the sixth stoking. The stoking position was rotated amongst all the members during the run. Each team uses 3 T2k units in the standard charring procedure developed locally. These units are place at strategic positions in the field to minimize feedstock carrying. Each unit is filled with char and quenched in succession and after lunch the char was bagged. New biochar ideas
Photo 4) The standard WH T2k – This is the evolved 2 m3 LLU trough. It is the workhorse of the Warm Heart line, proving itself suited for major distributed low-tech biochar production in small farmers’ fields and forests, utilizing cornstock, rice straw, fruit tree prunings or bamboo. Pictured here is the beginning of a successful test with mixed feedstock consisting of (to the rear of the unit) corn husk and fruit tree prunings, and (left foreground) lemon grass, and behind that corn stock.
Photo 5) A pile of fruit tree trimmings to be charred in a T2k.
Photo 6) Fruit tree trimmings charring in a T2k. The 2.3 m length easily accommodates almost all fruit tree trimmings while the standard T2k’s 1.6 m width means it can handle most all of the branchy trimmings without additional processing.
Photo 7) The wet blanket snuff. In areas where water is scarce or difficult to transport in, the water needed can be greatly minimized by a first light quench of the top hot coals followed by covering the char and unit sides with a water soaked heavy canvas blanket.
Photo 8) Charring bamboo feedstock in a standard WH T2k LLU on site in a forest setting. Light branches burning to build the hot coal with larger lengths in the background. New biochar ideas
Photo 9) The resulting char load. The resulting bamboo feedstock char has been heaped in one end to facilitate finding hot spots and to expose the unit’s water table so the earlier quench water can be reused on hot spots. In addition, this allows soaked char to drain. Such strategies lessen the quench water needed even if a wet snuff blanket is not used.
Photo 10) The WH T2k LLU can also produce char from rice straw without smoke pollution. The burn is started by lighting a small pile of rice straw in the center of the unit.
Photo 11) Early straw stoking – spreading the fire. Straw is added with the aid of a long metal handled pitch fork, placing one forkful at a time in very quick succession.. New biochar ideas.
Photo 12) Rice straw – drag stoking. Several methods of stoking were developed to allow clean, smokeless charring without excessive ashing of the straw. One of these methods consisted of dragging the forkful of straw along the surface of the char load to deposit a burning band of new straw and resulting char.
Photo 13) Roll stoking rice straw. Another stoking method consisted of rolling the forkful of straw along the surface until the outside of the ball was aflame and then depositing the flaming ball where desired. The flames on the outside of the ball consumed the smoke generated by the igniting straw inside. New biochar ideas from New biochar ideas from The Warm Heart team. Excellent innovations in biochar.
Photo 14) Pit stoking in late burn. A third method of stoking that can be employed after a deep bed of char has been built up is to rake a pit in one section of the trough and deposit balls of flaming char in it until it is filled with char, then move to the next section of the trough and repeat. Note the smoke being generated by the igniting straw being burned as it is sucked up the flaming updraft.
Photo 15) Rice straw char. A cross-section of the char load as it is being bagged a shovelful at a time with an eye out for hot spots.
The second half of the post will feature photos of the XLT 1k and T200 units, general schematics and a table of dimensions for all of the standard WH Trough units.
Me le aloha – frog, for Warm Heart, UB International & UB Siam.
This is so great I did not want to edit any of it. So here you are folks.
Is it necessary to cover this machine to reduce smoke ? Is there any cooling system to get liquid pyrolysis ? Is it easy to transfer ? Its shape is really good I think we can put on waste easy very very simple
E, Ghada elmasry, aloha kaua-
Thank you for your interest in the FC troughs. I’ll answer each of your questions in order.
Is it necessary to cover this machine to reduce smoke?
No. The unit is started with a small fire in the bottom (see photo 10 to get an idea of the starting fire for the T2k for making char from rice straw) then feed stock is added in such a way that the air currents generated by the heat of the fire and the shape of the unit keep the gasses with the heat stream until they are burned or, when so cool, they are returned to the flame stream and burned (see photo 14 for an example of the latter). Stoking takes some practice but it is a skill that is easily mastered for a wide variety of dry feedstock. However, we are contemplating experimenting with long ‘clam shell’
Is there any cooling system to get liquid pyrolysis?
No. These units are specifically designed to keep the technology as simple and inexpensive as possible. If you would like to produce liquefied pyrolysis gasses I would suggest setting a simple barrel retort over the trough on a tripod that that allows convenient stoking of the trough. It would be a good use of the heat generated. A simple pivot arm could be used to replace the barrel retorts during longer burns.
Is it easy to transfer?
Yes. It is easy to transport even the T2k units. From base to field they are usually transported in a small light pickup. One or two can be loaded by 2 persons. With additional personnel to load and unload a 3rd can be added to the stack. We work with 3 units to a team, so have never had cause to try to carry more. At the site, the units can be hand carried. The T2k units are easily carried by 4 individuals. The T500 is designed for carrying by two persons over long distances by personnel used to carrying loads in such terrain.
Me ke aloha – frog pattamo_kop@yahoo.com
E, Ghada elmasry-
My response to your first question seems to have gotten cut off at ‘clam shell’. It should have gone on as: ‘clam shell’ cover doors meeting at meeting at about 45° above the trough proper. They would overlap the sides with space to catch hot secondary air and have a gap where they meet at the top to vent the hot, burnt gasses. This would serve as a structured afterburner, but could also be used one side at a time to be more of a wind shield / role down draft generator when necessary.
Me ke aloha- frog
What gauge steel is used for the body of the trough?
How durable are they?