Diesel engine running on gas

[fredericponcet]

Okay ... if I understand correctly:

no modification to be made on the engine itself (the injection pump regulates itself the quantity of fuel oil according to the volume of gas aspirated)

but it is necessary to regulate the injection of gas ... according to the mode? If the speed increases, the gas flow is reduced, if the speed decreases, it is increased.

I understood well ?

Subsidiary question: if the gas is injected on the admission, it can be at atmospheric pressure? We can regulate with a simple butterfly downstream behind a regulator, for example?

[chatelot16]

if the regulator of the injection pump works well the speed is constant ... there is no information to take on the speed

it is necessary to detect the quantity of diesel injected by the pump: if the pump injects too much diesel, the gas must be increased ... if the pump no longer injects enough diesel, the gas must be reduced before it I don't have enough diesel for ignition

if it has to be done electronically, we can leave the diesel pump in its original state, and put a piezoelectric sensor on an injector pipe, to capture the injection time and control the gas

but what gas? LPG is absurd it is more expensive than fuel oil!

only bio methane is interesting

for what power?

in small power a gasoline generator is cheaper than a diesel, and plau easy to adapt to methane: without electronics!

diesel is good for big power, or we find diesel more easily ... and again, I find it only works with gas simpler ... I saw large diesel transformed with candle at place injectors

[fredericponcet]

but what gas? LPG is absurd it is more expensive than fuel oil!

only bio methane is interesting

for what power?

in small power a gasoline generator is cheaper than a diesel, and plau easy to adapt to methane: without electronics!

diesel is good for big power, or we find diesel more easily ... and again, I find it only works with gas simpler ... I saw large diesel transformed with candle at place injectors

Chatelot16, you seem very competent, but you have the art of answering questions based on your concerns and ignoring those of others, which you consider absurd a priori ...

So I'm going to give you two details:

1) the Diesel generator, I already have it (it is 16 kW). So buying a petrol group would be an economic nonsense for me.

2) if I ask myself the question, it is not for the pleasure of installing an LPG tank in addition, but because I ask myself the question of producing biogas, and what I could do with it ...

[Did67]

Some elements here: https://www.econologie.com/forums/post262362.html#262362

But we acquired a group with all its electronics, in a soundproof box.

What I know, to transform the Scania 6 cylinders:

a) change of injectors / transformation of the cylinder head: the temperature too high and the reduction of the lubrication of the injectors destroys the original injectors.

So "mini-injectors", crimped in a copper ring, which itself "bathes" in pipes which provide the cooling liquid ... It is quite heavy, as a transformation

b) our group consumes around 55 to 65 m3 of biogas and around 2,25 l of diesel per hour, at 1 rpm, 500 kW

c) the electronic box plays on the two parameters: at startup or if the quality of the gas decreases, the consumption of diesel increases ... But it is locked at 2,25 l / H. The group would still turn below when the gas quality is good. But Schnell does not. Some German farmers hacked at their own risk.

d) the gas, which arrives at very low pressure, is pressurized by a turbine (hypersecured! most sensitive part!). It is added to the combustion air filtered by a venturi.

Gas consumption fluctuates, but I don't know how. No doubt, but I remain careful, the turbo pressure, which also varies ...

I did not observe an intake valve, but I am a good handyman, not a trained engine manufacturer at all!

So on your real problem, I can't really help you.

e) pay attention to corrosion of the engine and more generally of the installation. You have to drastically reduce the rate of H2S, which is very variable depending on the quality of the biogas (and what the digester "eats"). H2S is tocic for us. It is a super corrosive for mechanics, including stainless steel !!!

This is the 1st engine problem / The 1st source of breakage!

[Did67]

On reflection, for a less complicated system, I think:

a) that it is necessary to leave the injection pump and put the idle

b) regulate by admitting gas; even if the engine is running at 1 rpm due to the energy of the gas, the pump will inject at each revolution just the minimum amount of diesel, whatever makes the engine idle - this will serve as a match, even at 500 1 turns; the regulator of the injection pump will try to reduce this quantity, but it seems to me that the minimum is "tared" [but there is now, on diesel cars, the injection which is cut to save / reduce pollution ; this was not the case on the old pumps; so it depends on what you have)

c) for gas injection, I think you need to "hijack" an LPG system, with electronic injectors in the intake manifolds ... But I don't know what the adjustment attitude we have on the electronic calculators: biomethane, with about 50% of CH4, will be much less rich than LPG !!! It is therefore necessary to double the impulses !!!

[chatelot16]

inject gas at the intake of an unmodified diesel, but what will become of the injector when the engine is running at full power thanks to gas and with a low flow of diesel?

if at schnell you need a special cooling of the injectors, what will it be on your 16 kW engine

the only way to know is to try, a little expensive if the test causes breakage

beware gas works well in direct injection diesel, like big trucks

if the 16kW diesel is an indirect injection with a ricardo comet combustion chamber, the chamber creates a hot spot which will explode the gas during compression before pmh

[chatelot16]

a) that it is necessary to leave the injection pump and put the idle

no because at idle the injection pump is speed regulator! it sends what it takes to run at idle speed, as soon as it runs faster it does not inject anything at all, so no minimum dose to ignite

another point of view, the speed regulation of an injection pump is more easily precise and quick than a regulation by gas, so it is better an approximate regulation by gas, and let the diesel make the exact regulation

[fredericponcet]

if the 16kW diesel is an indirect injection with a ricardo comet combustion chamber, the chamber creates a hot spot which will explode the gas during compression before pmh

It is a Slanzi DVA 1500 (in an old Cérès 20 KVA group). I would like to keep it as long as it runs ...

In short, what I understand is that it is better that I use biogas otherwise. Anyway, the idea is to exploit the production of my dry toilets, therefore a gas production probably modest. It is a medium-term project (not for this winter!)

Furthermore, if I can replace the group in the future with any other quieter solution, I will try to do so. Steam or Stirling, whatever. I have never heard a Stirling running, but it is impossible for it to make as much noise as a Slanzi DVA 1500 ...

[Did67]

no because at idle the injection pump is speed regulator! it sends what it takes to run at idle speed, as soon as it runs faster it does not inject anything at all, so no minimum dose to ignite

The news, yes!

But not the "old pumps"; there was a "physical" centrifugal regulator, with a minimum wedge ...

Now, in fact, it cuts to save / pollute less.

[fredericponcet]

But not the "old pumps"; there was a "physical" centrifugal regulator, with a minimum wedge ...

Yes I think mine works more like this ...