Some figures on the biogas?

[chatelot16]

the air chamber loaded by a weight will be less worse than inflated to its elasticity, but still very variable, because the contact surface varies completely with the volume

solution used in large methanizers: flexible tarpaulin above the tank, methane below, air above, inflated dome above

the dome is inflated at constant pressure by a small fan: whatever the volume of methane below it puts methane at this inflation pressure ... just slightly increased by the weight of the membrane

another advantage the dome is always inflated correctly to support the wind

[Did67]

We agree, that's what's going to be with us.

[Did67]

the air chamber loaded by a weight will be less worse than inflated to its elasticity, but still very variable, because the contact surface varies completely with the volume

If I remember correctly, it's a question of operating a gas lamp ... the flow rate will vary depending on the pressure, so the light ...

Otherwise, it remains only to reinvent the gasometer with two nestable pots, one overturned in the other with water ...

[chatelot16]

I did not invent this flexible membrane under an inflated dome I simply see it on most of the description of large methanizer!

the gasometer is the simplest to do in DIY with the means on board

not only does this system give constant pressure, but the height of the bucket makes it possible to calculate exactly the volume of gas: hence the name of gasometer: its function is as much to measure as to store

a 200 l barrel full of water

a 60 liter bucket with a string attached to the suspended bottom with a pulley and a counterweight

a bent pipe which goes underwater and ends in the bucket

without the counterweight the bucket would not stand, would lie on its side and let the gas escape

if the bucket is not heavy enough it will not be stable: add some weight on the edge of the bucket below, offset by a heavier counterweight

[chatelot16]

it seems to me that a diesel for methane co-combustion has a slightly reduced compression ratio

For information / not to be right!

With biogas, the compression rate is kept high because the high rate of CO² allows it: the high rate of CO² prevents self-ignition.

With natural gas, auto-ignition is indeed a problem. So we must actually lower the compression rate of Diesel which loses part of its interest, the higher efficiency linked to a higher compression rate and therefore better combustion.

I do not know formally if the initial compression ratio is maintained. To my knowledge yes. I saw work on the cylinder head to install smaller injectors, with a special cooling system. But not piston / connecting rod / crankshaft ...

see "klopffestiggheit" (resistance to self-ignition) here: http://www.schnellmotor.de/sm/schnellmo ... rinzip.php

your information is precious! better than my general, I don't have the chance to be a real customer for this kind of thing

on engines with large turbo, you can adjust the compression ratio with the regulation of the turbo, so optimize without changing the mechanics

and conversely as diesel engines are manufactured for different turbo, different pistons are often available to make different volumetric ratio

[Did67]

Indeed.

If you take this leaflet for example, the same SCANIA engine with 6 cylinders / 11,7 liters is available in 4 versions: http://www.schnellmotor.de/sm/pdf/SCHNE ... _kW_DE.PDF

Note the electrical efficiency ("elektr. Wirkungsgrad") of 42 to 47%.

Note also that the last model has the same electrical power as the previous one (264 kW), but the power of the motor / generator has been lowered to 235 kW (therefore its consumption); on the other hand, a turbine has been added to the exhaust after the turbo, which produces an additional 30 kW ("free" because normally lost in the exhaust; spins at 49 rpm! It is on the photo on the left, at the bottom right).

As you can see in the photos, all the engines are turbocharged + 1st water cooler (to recover and enhance the calories: it is the square block on the pipes above the cylinder head) then a second cooler with two radiators air at the front (there, the calories are blown "out" - see hatch in the doors) ...

In the end, the "electricity + recovered heat" efficiency is around 80 to 82%. The rest is the heat lost by the exhaust and by this 2nd cooler.

[Did67]

I did not invent this flexible membrane under an inflated dome I simply see it on most of the description of large methanizer!

Yes Yes...

This is what we will get.

In Germany, there are installations with a simple membrane, which "deflates" so ... It still works.

But the trend is towards double membranes, with finer regulation. Maybe also an "aesthetic aspect" ...

I do not remember (I would have to see that with our design office), it seems to me that in France, it is compulsory (classified installations, with all the traintrain of standards) ...

[chatelot16]

my anaerobic digestion experience has been abandoned for a few years, but I will get back to it

I am missing an important piece: fine grinding of the waste before introducing it into the tank

I like to introduce the waste immediately into a water tank without grinding, to avoid any storage in the air of waste and avoid the emission of odor, but then you have to grind the waste in the water so that it runs well in pumps and hoses

I see the pump macerator planned for the lifting of wastewater: not only is it very expensive like 1500euro but I am not sure that it is solid enough

what kind of grinder will there be in this installation? even if it's too big for me it will be instructive to see the principle

[Did67]

Powering our system is quite complex:

- manure, stored as before in a covered manure to avoid percolation; but greatly reduced storage time; this will be digested +/- continuously and in fact, the stock should disappear ...

- green waste / lawn mowing / stolen energy crops: silage and / or continuous feed; concrete silos; no more odor than an agricultural silo (it is above all the waste which "lags" and which ferment in juices which develop odors; with a concrete slab and water drainage, much less problem; our area is already " nickel "currently - (when I see the surroundings of some silos !!!)

- canteen waste / slaughterhouse waste and agro-food industry waste (flotation grease, "misfires" and production starts): are treated in a sealed building, under vacuum, with air treatment; the truck enters the building / closing the door / extracting air starts; the air passes through a "biofilter"; this waste is pasteurized (legally compulsory) then stored in a closed concrete tank to be injected as and when required ...

For these last two points, we will be "perstataires" for the structures which are currently paying dearly to get rid of this "waste". We proposed a 50/50 market ...

On the other hand, we "offer" the digestate to the farmers participating in the project, with the idea of ​​reducing the consumption of chemical fertilizers in the area. It is a "political" choice. We could have sold this digestate, again 50/50 (reduced to the fertilizer unit, of course).

We are at the limit of a subdivision. The question of odors is therefore very sensitive.

Normally the hope is to reduce odor emissions compared to "before" !!! A "nose" has been commissioned to smell the place before work and will come back after for an expertise.

[moinsdewatt]

Concrete example of agricultural methanisation in Langolen (29)

10 Oct 2012 enerzine

This anaerobic digestion unit, which has just started, operates from bovine effluents from SCL Odet Lait and flotation fat from processing stations in the food industry located nearby.

The farmer - Daniel Barré - said in the local newspaper that the cost of this investment had been estimated at 2 million euros. It received grants from Ademe and the European Regional Development Fund (ERDF) for a total amount of 320.000 euros, the rest being financed by a bank loan.

.............
The installation will be able to recover annually:

- 4.500 tonnes of slurry from SCL Odet Lait
- 2.150 t of manure
- 2.350 t of floatation grease

In return, it will produce annually:

- 777.000 m3 of biogas
- 1.950 MWh of electrical energy
- 2.340 MWh of thermal energy including 1.880 MWh used for heating greenhouses
- 6.900 t of liquid digestate and 1.200 t of spread dry digestate.
...........

http://www.enerzine.com/12/14562+exempl ... n-29+.html