Bio-methanation at the Agricultural College of Obernai

[Did67]

No. Not quite.

There is a schedule. I need to take stock with the director. We tried different angles / different regimes ...

From memory, this is about 50% of the time. We try to reduce, because it is one of the main "gray energies" ...

But in fact, the fact that these stations operate 24 hours a day for around 24 days a year means that there is a colossal multiplier.

For example, for the engine, we have had feedback from the maintenance team. In its "deflated" version, at 180 kW electric, almost all the motors installed have passed the 100 h mark. For a Diesel, which would drive a car running at 000 km / h on average, that would make 60 million km on the clock!

At 240 kW, obviously, the motor is a little more used, it "knocks" a little more and that accelerates the wear [when I say "knocks", I mean that the noise is a little more marked inside ; of course, it turns perfectly "round"! There was an update of the software that manages the engine and we noticed that this lowered the sound level !!!]

[Philippe Schutt]

Stainless steels are mainly oriented towards corrosion resistance, and for this we lower the carbon content. Therefore there are few stainless steel alloys on which one can make an effective heat treatment.

I only know:
AISI 17-7PH
AISI 15-7PH

Then you have to see the cost / life ratio ...
We can also consider a surface treatment, such as chrome plating with a thickness of 0.2-0.3mm. It's not expensive and it can pay off;) provided the part is very rigid, otherwise the chrome will crack and flake.

[Did67]

I guess they know all of that at SUMA ???

They are not the only ones on the market ... So it is not entirely in their interest to take their customers for cons ...

Especially since on this kind of project, we call on a builder ... So the experience, if it is bad, will necessarily "go up" and impact future sales ...

But yes, stainless steel is not hard. I always buy my Opinels with the famous "carbon" blades, which oxidize but cut! Never found stainless steel which cut durably (unless there are "notches") ...

The replacement of the two propellers is scheduled for September 22. I will keep you posted. + photos, if I think about it!

[chatelot16]

for ordinary knives we have the choice between ordinary stainless steel not hard enough to cut well, and ordinary carbon steel which cuts better but rust

by putting the price there are steel both hard and stainless

now there are even ceramic knives that cut very well and are even more unalterable than stainless steel

but we must remain reasonable: the mixing propellers of a methanizer are large parts that cannot be made of precious materials: we must find the economic optimum between wear and cost

stainless steel is quite expensive: therefore useful when it allows to make durable parts ... if it is to last 2 years what good is stainless steel? it gives me the impression that the steel to shoe the donkeys would have lasted the same time ... or even longer because the same price in ordinary steel would have allowed to put thicker

see also cast iron which has quite surprising quality: there are special cast iron, both resistant to wear and corrosion, and much less expensive than stainless steel ... but cast iron means that parts have to be made more thick heavier donation, so the rest of the mechanics have to support the weight

[Philippe Schutt]

it's all about compromise, in mechanical parts. Must see what is put forward.
My brother gave me an alloy composition for my cold dies and they haven't worn out in 20 years. Yes, we get very close to the cast irons, and the machining is followed by a heat treatment. it is impossible to trace it with a needle. I can ask him again which alloy if it can be useful to someone.
Conversely, the punches that I buy are in a much less resistant alloy, and do not hold more than 10000 holes even when oiling.
ceramic blades are fragile I prefer to blunt than break.

Nowadays there is a strong tendency to reduce or simplify heat treatments, for example on chisels I soak them in oil and they hold 3 times longer before re-sharpening. And nobody knows how to quench in 3 steps, apparently. Ditto for chrome plating, fallen into disuse in my opinion a question of fashion ...

[Flytox]

Nowadays there is a strong tendency to reduce or simplify heat treatments, for example on chisels I soak them in oil and they hold 3 times longer before re-sharpening. And nobody knows how to quench in 3 steps, apparently. Same for the chrome plating, obsolete in my opinion a question of fashion ...

Rather for an HSE question, the health, safety, etc. constraints are too cumbersome to manage, plus a layer with the Reach regulations.

http://ec.europa.eu/enterprise/sectors/ ... dex_fr.htm

REACH is the regulation on registration, evaluation, authorization and restrictions of chemical substances. It entered into force on June 1, 2007. REACH rationalizes and improves the old European Union (EU) regulatory framework on chemicals.

The main objectives of REACH are to ensure a high level of protection of human health and the environment against the risks that chemicals may pose, the promotion of alternative test methods, the free movement of substances within the market interior and strengthen competitiveness and innovation.

REACH places the responsibility on industry to assess and manage the risks posed by chemicals and to provide adequate safety information to their users. In parallel, the European Union can take additional measures concerning extremely dangerous substances, when additional action at European level proves necessary.

There are plenty of surface treatments to control corrosion / wear but if they are "affordable" for large series, they are often not competitive individually ....


http://www.bodycote.com/fr-FR/services/ ... tings.aspx

Ceramic coatings

Chromium oxide ceramic material thermochemically assembled on the parts of a part specified by the customer, including external diameters, internal diameters and certain hidden holes and cavities. The individual ceramic particles are submicron in size and consist of mixtures of a selection of ceramic materials assembled together and with the substrate.

Benefits
Applications
Process

Hardness
Reduced friction
Corrosion barriers of absolute density and devoid of any porosity
Increased assembly strength
Extraordinary wear resistance
Applicable to bores with complex and internal geometries
No measurable buildup on top of veneer / coating
No pre-grinding required
Lifetime of veneer / coating multiplied by 4 to 10 times in the most corrosive environments
Cycle resistance / thermal shock
Electrical resistivity

[Philippe Schutt]

Not said. In galvanic treatment and in general the baths, we hang the part on the chain and it goes with the large series. Finally as long as we stay + - in the same size and weight.
But the school will not go into these details, it will let the supplier do it.

[Did67]

I have not yet recovered the photos!

But already some elements:

- small blunder of the design office, which put stainless steel propellers in the digester where it was not necessary; these propellers are always flooded; they are not exposed to H²S; stainless steel propellers are manufactured for ripeners, where they can be "in the air", so risk corrosion by H²S

- we have therefore replaced by the appropriate model, in "hardened" steel (I do not know which alloy), but not in stainless steel; life expectancy of at least 3 years a priori ...

Since then, we have been overproducing gas, with occasional switching on of the safety flare. The digester, better stirred, produces much more gas with roughly the same ration (which has been reduced since).

At the moment, processing of grape marc, in agreement with the association of local winegrowers. We also ensile them, to spread out the consumption, our goal being always to change the rationing very gradually (a digester should be treated like a ruminant rumen; therefore no sudden changes in rations if possible; the more we "push" the production of gas, and the more the digester is "sensitive" to indigestion!)