Making a biomass boiler ... flameless

[marc91]

document in word format on the manufacture of a biomass boiler

https://www.econologie.info/share/partag ... hfShqs.doc

Manufacturing dossier for a biomass boiler

This boiler is based on the work of Jean Pain, who discovered that a pile of decaying plant waste of several m3 emits a temperature of up to 75 ° for several months, so it was heated.
This boiler does not emit co2 because it does not consume any material, it recovers the heat from the decomposition of plants.

Manufacturing:
the ideal would be stainless steel but expensive and difficult to weld (we can also recover a tank from an old stainless steel heating flask), failing that we will be satisfied with heating quality steel, welded with arc, protected against corrosion by treatment.

To get started, get:
a tube diameter 300 long 1,5m (found in scrap yards)
two domed bottoms diam 300
two tubes 26x34 long 50cm
two small pieces of 15x21 and 20x27
iron U (thick) four pieces of 50cm
two welding flanges 26x34 DN 50

bend the U-irons at 90 ° to about 35cm (heat them red with a blowtorch) to make the feet

pierce the domed bottoms in their center (one at 15, the other at 20)
weld the domed bottom drilled at 15 at one end of the 300 tube (top of the boiler)

make a turbulator * (it must slow down the circulation of water in the boiler), slide it into the tube of 300 and weld the other convex bottom weld a piece of threaded tube (15x21 on the side drilled at 15 for the purge) and (20x27 side drilled at 20 for emptying)
weld the feet along the bottom of the boiler (make sure to weld ALL sides)

pierce the body of the boiler about 10cm from the upper edge at 26, point a 26x34 tube at the square and point the flange to be welded (check the squareness) do the same at 10cm from the lower edge (return pipe) and weld the whole

put the boiler vertically, it must stand upright very stable
place perforated plates with gaskets on the flanges, valves on the drain and purge, inflate with air (at least 4 bars) and test the welds using a product for gas leaks
in the event of a leak, repeat the welds (grind and resume) otherwise fill it with water, have a plumbing pump lend a test pump and pressurize water at 20 bars for 4 hours.

Put a good coat of anti-rust paint on the entire boiler (also the feet), let dry at least a week before applying an epoxy paint

Put the boiler in place and connect to the heating circuit with isolation valves (be careful to put a 3 bar valve upstream)

the boiler must be kept straight during loading (fix it on the ground or against a wall with a minimum distance of 50cm from the wall), cover with 3m3 of fine ground vegetable waste (wood, brush, brambles) sprinkle with 5 buckets of rain water, leave for three days, then cover with 10cm of soil.
The reaction begins between 15 to 20 days and lasts more than 8 weeks, after which the temperature decreases, when it is no more than 30 ° we can remove the mixture that has composted and use it as or mixed with Earth .
Each year check the condition of the anti-rust treatment, carefully brush and redo the paints.

NOTE: several boilers can be put in a battery and run in turn. In this case, the waste must be stored in a dry place or produced as and when using a shredder.

[Christophe]

Seeing the 1st diagram I took a few seconds to understand what we were talking about because it was not a boiler but a balloon ...

I finally renamed the title of your subject to make it clearer and to arouse curiosity.

Regarding the concept, it is more, I think, a heater (therefore put upstream of a boiler) than a stand-alone boiler.

In addition, the quantities of plants must be significant. I know the methanogenic powers of most plants but I don't know the thermal potentials for decomposition (necessarily weaker than methanogenic powers ... right?). This is where we should start ...

Has a full-size model already been built?

[Gaston]

Does extracting heat from decomposing material not affect decomposition

The compost heap at the bottom of the garden does not like to be cooled at all ...

[cortejuan]

Hi,

same remark as Gaston, the extraction of the heat slows down the action of the bacteria and it will form around the balloon a less hot zone because not very active, its heat will come from the rest of the heap which will transmit (badly) its calories, so I am amazed that the system works other than as a means of slightly increasing the heat of the heat transfer fluid.

That said, it is undoubtedly the main source of heat which is the determining element: if the return of the main heating arrives at 30-40 degrees, this heat will activate the bacteria which will raise the temperature of the pile, the water can then exit with a gain of a few degrees compared to the inlet.

But how many m3 does it take to maintain microbial activity?

What type of waste?

What isolation from the heap?

There are still lots of questions on the subject.

cordially

[Ahmed]

I have already answered this subject, having followed the experiments of the emulators of Jean Pain.

In summary:
- there is confusion between the caloric mass of the heap in fermentation and the heat flow produced;
- the wall effect, at the interface between the substrate and the exchanger, causes the ground material to dry out, which then becomes insulating.

I also note two errors in the particular case considered here:
1- the volume of wood is very largely underestimated;
2- the assertion that the decomposition of wood excludes the release of CO2: this release is slower, but equal to that of combustion (for the part of material which is transformed, since, contrary to what is asserted, it there is indeed a decrease in plant mass).

Previous experiences have largely demonstrated the impasse of this process even though the conditions of implementation were very favorable: mass of ground material and large exchange surface (by winding a Socarex pipe) ...

To echo the message of cortejuan, there is no need for a calorific contribution to start the activity of bacteria ...

[marc91]

Seeing the 1st diagram I took a few seconds to understand what we were talking about because it was not a boiler but a balloon ...

I finally renamed the title of your subject to make it clearer and to arouse curiosity.

Regarding the concept, it is more, I think, a heater (therefore put upstream of a boiler) than a stand-alone boiler.

In addition, the quantities of plants must be significant. I know the methanogenic powers of most plants but I don't know the thermal potentials for decomposition (necessarily weaker than methanogenic powers ... right?). This is where we should start ...

Has a full-size model already been built?

Yes, jean pain had built a heap 3m high and 6m in diameter, but this one included in its center, a watertight tank which produced Biogas, for heating it had surrounded the tank with 200m of garden hose around of the tank, which allowed it to come out of the water at 60 °

[marc91]

I have already answered this subject, having followed the experiments of the emulators of Jean Pain.

In summary:
- there is confusion between the caloric mass of the heap in fermentation and the heat flow produced;
- the wall effect, at the interface between the substrate and the exchanger, causes the ground material to dry out, which then becomes insulating.

I also note two errors in the particular case considered here:
1- the volume of wood is very largely underestimated;
2- the assertion that the decomposition of wood excludes the release of CO2: this release is slower, but equal to that of combustion (for the part of material which is transformed, since, contrary to what is asserted, it there is indeed a decrease in plant mass).

Previous experiences have largely demonstrated the impasse of this process even though the conditions of implementation were very favorable: mass of ground material and large exchange surface (by winding a Socarex pipe) ...

To echo the message of cortejuan, there is no need for a calorific contribution to start the activity of bacteria ...

the insulation was it seems to me ensured by a layer of earth of 10cm, it is indeed a schematic diagram and the mass of materials also seems to me insufficient to ensure such production.
that said, being a child when we put our hands in silage (fodder kept in a wet pile) we managed to burn ourselves seriously !!!

[marc91]

1. Energy recovery:

This sector, very little known today, developed with the energy crisis of the 70s and 80s. As we have seen previously, composting generates heat due to the action of microorganisms. This heat has two possible "fates": 1. a part is used for the fermentation process by raising the internal temperature of the heap and evaporating the water; 2. the rest, surplus, is lost to the outside. The principle of energy recovery from compost will be to recover this energy released either at the heap level or at the fermenter level (if the composting takes place in a closed system). To do this, we can:

- install a water-compost exchanger in the fermentation mass (polyethylene or polypropylene pipe) and circulate water there which gradually heats up on contact. In 1980-82, the association SOLEIL VERT in Saint Aulaye (Dordogne) experimented with the heating of showers in a stadium by composting crushed wood. We calculated for this purpose that a heap of about 25 tonnes of ground material (i.e. 80 m3), with an average internal temperature of 65 ° C, made it possible to raise 22 liters of water in 473 days from a temperature average of 225 ° C (city water) at an average temperature of 12 ° C (hot water on the meter). It was thus calculated that the heap supplied a total energy of 45,5 kilocalories, or 1 kW.hour. The average installed power over 426 days is therefore 810 Watts, or 1 W / tonne, with 659 W / t in peak power (fermentation peaks). Other experiments have been carried out in this direction, in particular by CEMAGREF.

[Ahmed]

Marc91, you write:

... being a child when we put our hands in silage (fodder kept in a wet pile) we managed to get seriously burned !!!

It is this pertinent observation which is at the origin of the error between mass and flux!

[cortejuan]

Hi,

to answer Ahmed on the starting capacity without energy input, we agree, it is the mechanism of fermentation of the piles of grass that rise to 70 degrees and the damp recovery that burns the shed. What I am saying is that a minimum temperature must be maintained and the explanation provided goes in this direction because the return to the heap must be at around forty degrees (since the available heat is 45 degrees). This return keeps fermentation at the best level.

cordially