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Author Topic: Liquid gas feed to burner...  (Read 537 times)

1967Brutus

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Liquid gas feed to burner...
« on: October 28, 2024, 12:40:52 pm »

Hi Gents,

Anybody having any experience with this? I see great advantages, and a few issues/dangers that I think can be controlled remedied.

For all clarity, my intention is NOT to feed the fuel to the burner nozzle in liquid form...
My intention is to extract the fuel in liquid form from the tank, and evaporate it en-route to the burner control valve.

The reason for this is simply put, to relocate the evaporation process from the tank to "another place, not being the tank".
The advantages I hope to achieve are:
-Constant temperature of the tank (no or negligable evaporation in the tank, thus no pressure drop)
-Constant composition of the mix in the tank (no "destillation effect" changing the ratio between propane and butane over time)
-Connected to this, no more need to either blow off the tank before filling, or run the boat until empty to prevent butane saturation, a half full tank can be replenished without effect on composition.

-liquid fuel extraction also means sloshing has no effect, therefore the tank can be filled to a higher level.
-elimination of the need for tank heating ("large" energy consumer if done electrically, in my case a significant extension of RX battery duration).

The downside is that either a double fuel feed (gas and liquid) are needed in order to start up on vapour, then switch over to liquid once the evaporator coil is hot, OR the need for temporary external heat during the start-up phase.
I am probably going to try the latter option, since I don't want to add a 2nd valve to my gastank.


As said, anyone having experience with this type of set-up, any do's or don'ts or things I overlooked?

Thanks in advance,

Bert
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rhavrane

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Re: Liquid gas feed to burner...
« Reply #1 on: October 28, 2024, 01:08:09 pm »

Bonjour Bert,
Yves (Kbio) has a great experience on this topic and I have personally tested once :https://youtu.be/1TdwdAKIFKE
This phase is more delicate to manage than the classic gaseous phase but allows the tank to maintain a constant pressure and therefore a constant power, especially if a pressure attenuator and a regulator are placed after the transformation of the liquid into gas.

In this case,as my tank could not easily receive a second valve and no attenuator or regulator for my "speed" boat. The pipe is heated by a tour around the burners before a big gas filter.

The only constraint is that at the very beginning of heating, the tube is cold, as is the filter where the liquid expands, so I have to open the gas just a little bit ti heat them, after, perfect, constant pressure 2 bar in the gas tank.

I applied the same principle on this other boat : https://youtu.be/A4smWk7YK8I.

So, if I had to give an opinion, I would say that it is the smartest and safest solution to have the "good" / correctly managed gas pressure as soon as you can install two separate valves on the tank, a good way two pre heat the pipe then cool it a little bit before  the attenuatr and regulator.
This is not exacly what I did, didn't I  ok2
 
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Raphaël
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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #2 on: October 28, 2024, 02:06:54 pm »

Bonjour Bert,
Yves (Kbio) has a great experience on this topic and I have personally tested once :https://youtu.be/1TdwdAKIFKE
This phase is more delicate to manage than the classic gaseous phase but allows the tank to maintain a constant pressure and therefore a constant power, especially if a pressure attenuator and a regulator are placed after the transformation of the liquid into gas.

In this case,as my tank could not easily receive a second valve and no attenuator or regulator for my "speed" boat. The pipe is heated by a tour around the burners before a big gas filter.

The only constraint is that at the very beginning of heating, the tube is cold, as is the filter where the liquid expands, so I have to open the gas just a little bit ti heat them, after, perfect, constant pressure 2 bar in the gas tank.

I applied the same principle on this other boat : https://youtu.be/A4smWk7YK8I.

So, if I had to give an opinion, I would say that it is the smartest and safest solution to have the "good" / correctly managed gas pressure as soon as you can install two separate valves on the tank, a good way two pre heat the pipe then cool it a little bit before  the attenuatr and regulator.
This is not exacly what I did, didn't I  ok2
 

Thanks, Raphaël,

Yes, I agree that a separate gas valve and liquid valve would be ideal, but... unfortunately same like in your video, a bit tricky to install (I prefer not to solder on my gas tank).
There are ways around that too by the way, but they require quite a bit of lathe-work, which in all fairness, I do not see myself bringing that to a good end.

My intention is as follows, I have this Portasol soldering set, which contains a really tiny blowtorch as well as a hotair blower for shrink-tubing.
I plan to make a holder for that Portasol, so I can use it to pre-heat the evaporator coil. Preheat for a minute, then carefully open the fuel valve and light the burner on low fire. Maintain a low fire with the RC control valve, after maybe 30 seconds or so, it should be good to go.

I know the heat requirement of the fuel to evaporate, and at low fire, 1W effective transfer should be sufficient, full fire requires about 6W. The portasol has a 60W burner, so I think that should work.
I need to see what kind of temperature the gas will have after the evaporator, because of course I think the Regner RC gas valve can get damaged if the gas is too hot, no?

So I think I need to be careful with the experiments here, and maybe play with the exact location of the evaporating coil (hotter or colder location on the burner tube). Maybe a heat exchanger between liquid phase and gas phase, to cool down the gas a bit to acceptable temperatures in order not to damage the RC valve.



Alas, it sure needs some more "thought experiments" before I will start doing things for real.
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Re: Liquid gas feed to burner...
« Reply #3 on: October 28, 2024, 05:09:04 pm »

Bonjour Bert,

I fully agree with you.

Other information I did not mention, my safety RC gas valves are just after the tank, they operate well on liquid as on gazeous phase and are never exposed to the heat.

Unlike attenuators/regulators which must receive the gas in the gaseous phase only.

The assemblies that I have seen included a winding of half a dozen turns of about 2 cm in diameter after the heating zone, apparently sufficient to cool the gas. 
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Raphaël
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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #4 on: October 28, 2024, 11:34:37 pm »

Bonjour Bert,

I fully agree with you.

Other information I did not mention, my safety RC gas valves are just after the tank, they operate well on liquid as on gazeous phase and are never exposed to the heat.

Unlike attenuators/regulators which must receive the gas in the gaseous phase only.

The assemblies that I have seen included a winding of half a dozen turns of about 2 cm in diameter after the heating zone, apparently sufficient to cool the gas.

Do you mean the Regner RC valve by that?

I wonder how well the Regner valve would control the flow in liquid phase, because that could also be a solution,albeit control could be a little bit slower...
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DBS88

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Re: Liquid gas feed to burner...
« Reply #5 on: October 29, 2024, 01:42:59 pm »

I am starting to learn how to use gas from the liquid phase, the reason being that I have a boiler that I need to supply significant amounts of heat to generate the steam volume needed. I am therefore a novice in this field but will share with you over a few posts what I have learned, the successes, failures and challenges of using gas in the liquid phase. I must start here by saying thank you to those who are helping me and teaching me, for without their experience I would be floundering in the dark.
For our model boats and steam plants there appears to be a point or rate of gas supply which is difficult to exceed, lets say its a number 10 jet. The slightly smaller number 8 gas jet is fairly commonly used with a flow rate of approx 90grams of gas per hour, yet even with this smaller gas jet many on this forum will be adopting measures to combat tank cooling/freezing. This occurs as the liquid gas in the tank vaporises to compensate for the gas vapour that is being used. As a result the temp of the tank and liquid gas drop and so does the gas pressure, meaning the flame in the boiler is less powerful so you make less steam, it's a vicious circle. Some place the gas tank in contact with the boiler to heat the gas tank, there are a variety of methods adopted, but all are aiming to keep the gas pressure up to maintain a decent flame.
My journey to using gas in the liquid phase started about 3 years ago, a friend built and sent me a burner designed to burn 300g of gas from the liquid phase per hour. The principle for using liquid phase gas is that you use the gases own naturally developed pressure (vapour pressure) to expel liquid gas from the tank and allow the liquid gas to turn to vapour away from the tank - avoiding tank cooling and the tank pressure falling. Each drop of liquid gas turns into approx 240 times as much gas and the rate of gas phase gas used is then controlled by the size of the gas jet. In other words the system should form a self sustaining equilibrium, where the gas escaping from the gas jet is replaced by an equal amount of gas (in liquid form) when vaporised. I have seen videos and spoken with people who use this system very successfully and they achieve exactly that, a system in equilibrium with virtually no tank cooling and a steady flame with a heat output that far exceeds our traditional burners.
Here is a video, the burner is alight with gas being burnt in gas phase straight from a commercial can, I then turn the gas tank upside down so that the gas is expelled as liquid, it is then vaporised in the pipework around the burner before being burnt as gas in the normal way. I have seen this done very successfully. If you try this,  don't expect that this will always be the case, I have learned from many trials what to expect and find that it is necessary to control the liquid gas flow rate, since too much liquid flow can result in liquid gas being expelled from the burner as a flame thrower and or the flame being extinguished (mixture beyond combustion range). That said this early test is a success in that it shows that it can and does work as well as what happens with too much liquid. I will share with you further experiences in later posts if you would like me to?
https://youtu.be/ATfw7SpJvr4?si=e7KRzEEEBoaCKkeN

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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #6 on: October 29, 2024, 01:50:44 pm »

I will share with you further experiences in later posts if you would like me to?


YES! YES! I would REALLY like you to...

For full disclosure and to prevent misunderstandings: I am NOT out to achieve "more fire", larger nozzles or such.
My intent is the simple avoidance of evaporation in the fuel tank, for reasons of constant pressure, omission of (in my case electric) tankheating, but also the elimination of destillation in the tank. Three factors that increase endurance, consistency and flexibility.

I have an average fuel consumption of around 60 grammes per hour, and full fire is in the neighbourhood of 90 g/h.

I am looking to control the fire with the same Regner valve as currently fitted, and if possible, I would like to refrain from a double fuel valve (vapour and liquid).

Whether that will prove possible, remains to be seen.
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DBS88

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Re: Liquid gas feed to burner...
« Reply #7 on: October 29, 2024, 02:16:46 pm »


I have a burner designed by a Gentleman known as Bobino and I have a number of different size jets with which to experiment to confirm the best option for supplying gas. Note these are not the std UK sizes of jet they are not No8, No6 etc, they are European sized jets, in fact for cost effectiveness they are actually 3D printer nozzles, far cheaper than gas jets


The burner is currently equipped with a 0.5 jet and I know it works well in the gas phase. I have been looking at the liquid phase information and want to experiment more with the liquid phase. I started using liquid phase with the Bobino burner in a very basic way with a pipe straight from a commercial disposable butane/propane can, it has not yet reached the steady state, with the valve fully open the flame is being blown out. Before putting the burner in my boiler and model boat I would like to achieve a steady reliable flame. I also would like to get to a point where I can also include a gas attenuator fitted to the boiler and a radio controlled gas cut off valve in the pipework.

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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #8 on: October 29, 2024, 05:00:03 pm »

So far, this is exclusively "thought-experimenting", nothing has been built, let alone tested yet.

My train of thought (for now) is as follows: I want to try and maintain the Regner RC gas valve. It can control a gasflow against the tank pressure as is.
Liquid feed or not, that controlfunction should not change IF the valve is still located in the part of the circuit that carries the gaseous phase, AFTER the evaporator coil. So theoretically, control should remain the same.
I am aiming for only slightly overheated state for the vapour, because I have no idea about the temperature resilience of the Regner valve. I considered coiling the evaporator tube around the burner base, but reconsidered: it probably makes more sense to use the flue gas at the stack for evaporating the liquid, for reason that:
A) this location allows for adaptation/modification of the evaporator coil without any disassembling of other components
B) at this location, heat will be availlable the most rapid (seconds after lighting the burner).
C) heat will have direct relation to the fuel flow so chances are it is easier to determine a proper coil length and have a steadier vapour temperature
D) temperatures in the funnel will be "reasonable" so much lower to no risk of overheating/decomposing of the gas, which I see as extremely undesirable.

I'll explain:

On a french forum that was brought to my attention, it seemed people were convinced filters before the burner are a necessity and the reason given would be that due to the liquid riser pipe in the fuel tank extending all the way to the bottom, dirt from the tank could enter the fuel system and pollute the gas nozzle. I think that is not the case (dirt pick-up from the tank), I think given that several people use evaporator coils at the base of the fire, where very high temperatures can be reached, this dirt is simply the product of overheating and subsequent decomposing (thermal cracking) of the fuel, causing carbon deposits. It would be my estimation that any dirt carried along by the "low velocity" liquid fuel, would fall stagnant in the evaporator and not be carried along with the vapour.
It would also be my estimation that since LPG is a reliquified byproduct of destillation, it would by nature be pretty much dirt-free, the same way destilled water is dirt-free. Dirt in small bottles of LPG also would be very dangerous, because it would render the non-returnvalve that is on each and every one of those bottles, very unreliable.

Since I am just theorizing, please feel free to shoot holes in the story so far, I can only learn from that.
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DBS88

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Re: Liquid gas feed to burner...
« Reply #9 on: October 29, 2024, 07:43:15 pm »

Through experiments I have confirmed two things;
1) There is no need to run with gas first to heat everything up and then switch to liquid phase, by just cracking the valve a little and lighting the burner its possible to go straight from the liquid phase, once the burner is alight its just a matter of opening the valve a bit more and then a bit more until the flame is at the intensity that you desire, it will then stay that way. Be warned though, in my set up it is possible to open the valve too far which results in a flame thrower with a bright orange flame or the flame being extinguished, neither of which is desirable.
2) A gas tank with two take offs, one for vapour gas and the second for liquid phase gas which requires a dip tube to be added so liquid is taken from the bottom of the tank, is not required (although it has advantages). It is possible to operate this system straight from a commercial disposable or a refillable tank, by turning the tank upside down and carefully opening the valve a little, lighting the burner then increasing the flow of liquid phase gas, it works, the liquid gas is expelled by the gases own vaporisation pressure, it then turns to gas in the pipework and is combusted as gas in the normal way.


As the experiments have continued and my confidence with using the liquid gas is growing. I do have a refillable gas tank that can supply gas phase or liquid phase gas, so have also started to use it. Here is a video, it is quite long but it's useful. Remember, this burner is using gas at a much greater rate, a rate that far exceeds a standard number 8 or 10 gas jet. The video shows the burner lit straight from liquid phase gas, the burner warms up and more gas is allowed to pass. Initially we see frosting of the pipework and valve, but not the gas tank. This is because the liquid phase gas is vaporising in the pipework, not in the tank as it does in a standard set up. The gas tank temperature does not get cold or get frost on it throughout the test. The frosting of the pipework is showing us that the liquid gas is vaporising in the pipe line rather than the tank which is positive. As the rate of flow of liquid gas is increased you will observe the frosting on the pipework disappear, but note, it disappears first from the tank end not the burner end, showing us that the  liquid gas is now in that part of the pipework and travelling towards the burner where it is heated and vaporised. Note also the outside of the burner is glowing red until later when more liquid gas is in the coils and the burner case is no longer red - it's cooled by the gas vaporising. Towards the end of the video the flame is less powerful and the gas valve can be opened all the way, this is because the gas tank has run very low, the liquid level has dropped below the level of the dip tube and the tank is now supplying gas phase gas since the tank is almost empty of gas. I hope you find this test both useful and informative.
https://youtu.be/i_Sl7iXL7wA



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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #10 on: October 29, 2024, 11:04:51 pm »

Thanks! That was extremely helpful.


It confirms what I hoped to see, as a concept, and above all, the possibility of starting straight on the liquid phase.

If you have info on it, I would like to know what kind of temperatures you see at the vapour line between evaporator and where the vapour line enters the burner head...
Because I cannot help but thinking your vapour would be pretty overheated, given how much heat it seems to absorb, and I am trying to estimate.

Your burner has a relatively short evaporation traject (three turns around the burner) with very intense heat supply and a high fuel throughput (looks like order of magnitude of say, 20 grammes per minute to me?).

I am trying to "estimate an extrapolation" (is that a way of putting it?) towards my intended set-up with a much lower fuel flow and a much more sedate evaporation proces...

Right now I am inclined to use much thinner gauge fuel tubing, and more length, in a much longer coil exposed to much lower temperatures.
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Re: Liquid gas feed to burner...
« Reply #11 on: October 30, 2024, 10:13:27 am »

Very interesting discussion, I follow it since I might also use a liquid phase system in my boat, if the normal gas tank will cause terrible with freezing.

I'd like to add that a gas filter is really useful, in my experience, because I have had trouble with impurities blocking the gas jet before. I have made the simplest of gas cookers by stuffing some cotton wool inside the gas valve exit, where the gas pipe nut screws to.
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Re: Liquid gas feed to burner...
« Reply #12 on: October 30, 2024, 11:21:38 am »

Excellent topic !
DS88 is an expert in liquid phase now !  :-))
Concerning a filter in the gas line , my point of view is that it does not hurt to install one. It takes more debris than the jet itself before to be plugged.
The gas inside the bottles have been filtered and treated before to be sold but the lines , tanks , installations from the well to the shop are full with scales & debris .
On personal installations , the problem is more often due to the weld inside the tank itself , above all if made on the shelf and lines welded. It is not always clean enough and some residues from the welding take time to be eliminated. Even by pulling the liquid 5 mm above.
Regards .

1967Brutus

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Re: Liquid gas feed to burner...
« Reply #13 on: October 30, 2024, 11:38:41 am »


DS88 is an expert in liquid phase now !  :-))


From another member I understood you yourself also are not unfamiliar with liquid fuel feed?
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Re: Liquid gas feed to burner...
« Reply #14 on: October 30, 2024, 11:55:55 am »

I do like to think things through and to understand how and why things happen, that said I do also try not to overthink things. To my mind we are using the gases own pressure to eject it from a container, the rate at which its ejected is in theory controlled by the size of the opening in the nozzle/jet. I also believe that hot gases burn more easily or combust more completely than cold gas. The question being raised is does the gas break down at high temperatures and cause issues with deposits in the jet? So what temperatures is this burner operating at and how hot is it making the gas?
The first clue is that the steel tube of the burner on occasion reaches a glowing red colour, so the tip of the burner is in the range of 550C to 750C - this then is probably the maximum temperature that any part near to the gas reaches. A quick internet search reveals butane and propane are very stable and only degrade in the presence of a catalyst in very controlled conditions in the range of 700 - 900C.
We know the copper pipe carrying the gas is not in direct contact with the steel and that the gas has a cooling effect. We also know that the silver soldered joints are not being affected so the temperature in the gas pipeline is definitely lower than 700C, at no point have we seen the gas lines copper pipe glowing red, so we can safely say the temperature is below 500C.
We also know that other people successfully use this system without problems. We also know and experience blocked gas jets from dirty gas or tanks when using gas in the usual way. So my conclusion is that using gas from the liquid phase is unlikely to be any more prone to gas jet blockages than using lag from the gaseous phase.
I am not an expert but I am experimenting and trying to learn, I now have more experience than I did a couple of months ago and have much to thank friends for that continue to help and support me on my journey of discovery.
What I have realised from my tests is that I have been trying to get the burner to work at the maximum rate - having tested the gas consumption I know it to be 360g/hr or 6g per minute - From this I know the burner will provide more heat than I need so I can now concentrate on operating the burner at a lower rate so aim to set it up at 75% max and for it to be consistent and reliable.
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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #15 on: October 30, 2024, 02:23:00 pm »

I do like to think things through and to understand how and why things happen, that said I do also try not to overthink things. To my mind we are using the gases own pressure to eject it from a container, the rate at which its ejected is in theory controlled by the size of the opening in the nozzle/jet. I also believe that hot gases burn more easily or combust more completely than cold gas. The question being raised is does the gas break down at high temperatures and cause issues with deposits in the jet? So what temperatures is this burner operating at and how hot is it making the gas?
The first clue is that the steel tube of the burner on occasion reaches a glowing red colour, so the tip of the burner is in the range of 550C to 750C - this then is probably the maximum temperature that any part near to the gas reaches. A quick internet search reveals butane and propane are very stable and only degrade in the presence of a catalyst in very controlled conditions in the range of 700 - 900C.
We know the copper pipe carrying the gas is not in direct contact with the steel and that the gas has a cooling effect. We also know that the silver soldered joints are not being affected so the temperature in the gas pipeline is definitely lower than 700C, at no point have we seen the gas lines copper pipe glowing red, so we can safely say the temperature is below 500C.
We also know that other people successfully use this system without problems. We also know and experience blocked gas jets from dirty gas or tanks when using gas in the usual way. So my conclusion is that using gas from the liquid phase is unlikely to be any more prone to gas jet blockages than using lag from the gaseous phase.
I am not an expert but I am experimenting and trying to learn, I now have more experience than I did a couple of months ago and have much to thank friends for that continue to help and support me on my journey of discovery.
What I have realised from my tests is that I have been trying to get the burner to work at the maximum rate - having tested the gas consumption I know it to be 360g/hr or 6g per minute - From this I know the burner will provide more heat than I need so I can now concentrate on operating the burner at a lower rate so aim to set it up at 75% max and for it to be consistent and reliable.

Despite being an engineer, I do not know those numbers by heart, so I had to look them up...
Not being pedantic, I just found information differing from yours.
According to my AI buddy on the web, Propane and Butane start decomposing around about 480 deg C, literal statement was:  "at the auto-ignition point, 480 degrees".
According to Wiki, the auto-ignition temperature is around 280 degrees, and that usually is the temperature where molecules become unstable, because they show a strong tendency to react with other molecules without external provocation. So now we have three values, appr 280 deg, appr 480 deg, and "above 700 deg in presence of a catalyst.
Given that the gas is pressurized throughout the entire fuel circuit until either nozzle or control valve, whichever of the values turns out correct, that critical temperature could be significantly lower.
Personally, I still think the chances of dirt being formed in the evaporator being higher than the dirt being carried from the bottle to the tank to the burner, and given that it happens also on vapourfeed installations, I would not be surprised if the dirt is being formed at the tip of the nozzle even...

On the bolded, I have a question: those that experience gas blockages in vapour fed installations, how intensively do they operate their equipment, and what consumption rates are we talking about?

Because here is why I can't grasp the concept of there being dirt in the gas:
-IF the blockages are being caused by dirt, it would be fair to assume, this dirt has certain dimensions, no? The gas as we buy it being filtered and all should suggest a certain max possible particle size.
-If above assumption is valid, it would also be fair to assume, that "trouble-interval" would be depending on nozzle size, no? A smaller nozzle would block sooner than a wider nozzle, if particles are the reason, because the smaller particles would pass a wider nozzle unhindered, but might get stuck in a smaller nozzle...

Reason I am pushing this subject a little, is that I an fairly certain that not many people run their set 80+ hours in a single year. Most people I talk to, speak of maybe 5 hours per year, if that...
But that is the kind of runtimes I am getting. I have a relatively small burner (max about 90 grammes per hour, average 60), meaning my burner has seen roughly 5 kilos of fuel and all of it throught that one single tiny nozzle. If dirt would be a problem, I run no filter and my burner has a relatively small nozzle, I would expect to have seen trouble allready...

I have anyway a very hard time imagining how dirt particles, once on the bottom of the fuel tank, would be carried away by the vapours above the liquid surface. I just don't see the mechanism... I could see that happening in liquid feed installations, but not in vapour feed systems.

Again, if this comes across as pedantic, I apologize once more, that really is not my intention. I see things that do not add up, and being a bit autistic, that does not go down easy.
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DBS88

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Re: Liquid gas feed to burner...
« Reply #16 on: October 30, 2024, 04:05:50 pm »

Having gone back through the discussion I believe you are looking to just evaporate the liquid gas somewhere other than the gas tank using a free source of heat, one that is not so aggressive as a coil of copper round the burner. From the work you have done to date on your boat you are clearly a very clever and accomplished engineer and I am confident that we can learn a lot from the experiments you conduct into adopting the use of liquid phase gas. I look forward to seeing how your project progresses since it is something that we could all benefit from. At the conclusion of your experiments it will be interesting to see if you have to use a blow torch burner or whether you can use a conventional ceramic burner with your final set up.
I will leave you with one other consideration that has been shown to me by others and that is the position of the gas cut off valve, it needs to be positioned so as not to leave a long run of pipe with liquid gas in it, otherwise it will take a long time for the flame to be killed since all the liquid gas on the nozzle side of the cut off valve has to be vaporised and burnt before the fire goes out!
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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #17 on: October 31, 2024, 04:01:05 am »

Having gone back through the discussion I believe you are looking to just evaporate the liquid gas somewhere other than the gas tank using a free source of heat, one that is not so aggressive as a coil of copper round the burner. From the work you have done to date on your boat you are clearly a very clever and accomplished engineer and I am confident that we can learn a lot from the experiments you conduct into adopting the use of liquid phase gas. I look forward to seeing how your project progresses since it is something that we could all benefit from. At the conclusion of your experiments it will be interesting to see if you have to use a blow torch burner or whether you can use a conventional ceramic burner with your final set up.
I will leave you with one other consideration that has been shown to me by others and that is the position of the gas cut off valve, it needs to be positioned so as not to leave a long run of pipe with liquid gas in it, otherwise it will take a long time for the flame to be killed since all the liquid gas on the nozzle side of the cut off valve has to be vaporised and burnt before the fire goes out!

That is a correct belief, albeit a bit simplified, because the main reason is not "free" (important but not dominant), the main reason for me is the constant pressure and the avoidance of destillation in the fuel tank. Those go hand in hand of course, but the constant pressure is desirable because of the more consistent process parameters, and the avoidance of destillation is, because in order to counter that destillation one has to blow down the fuel tank before filling, which is a waste. I hate that... Stupid, huh? It's mere cents, but still...

As for the burner, currently I have the burner that came with the Microcosm boiler (this one: M26D GAS BURNER FOR LIVE STEAM BOILERSNew - $48.00 microcosm-engine.com) and I have no intention to change the burner, it has so far been functioning well, and I believe it has more capacity than I need.

My job as a marine engineer, and especially the fact that I was lucky enough to serve for multiple years on the same ship, observing the results of minor mods, has led to a general "philosophy" that optimizing details goes a much longer way than most people think, and minor details (such as a proportional burner control instead of an on-off control, proportional feedwater control, and an as constant as possible boilerpressure) have positive effects that are not immediately visible, but work out positively in the entire process cycle from feedwatertank back to feedwatertank (if that sounds sensible), and every little detail in itself may seem insignificant, all those little bits accumulated can have a significant total result. I like to think my boat reflects that :D

Hence my focus on things like "is it dirt, or decomposition?". I don't mean to be pedantic nor obtuse, but I also have no fear of walking WAY far off the trodden path to see if there are other solutions than the "generally accepted" ones.

Your consideration about the shut-off valve is a very valid one, and I too have had my thoughts about that.
What you say there, is exactly the reasoning I had when commenting on one of your latest YT videos about the location of the control valve.
As of yet, I do not have an automated or otherwise controlled "emergency stop valve", but indeed, such a valve should be in the vapour part of the system in order to ensure an as immediate as possible outflow of fuel.

Right now I am leaning towards using a very small ID fuel line, coiled to form the evaporator. 1 mm inner diameter. Several reasons for that, one of them being that the ratio volume/exposed surface is better than a larger size tubing, but the other main reason is to limit the possible amount of liquid in that line. A 1 metre length of that tubing has an internal volume of about 0,8 ml...
I estimate to have about 30 cm of that wound up as the evaporating coil, which should result in an exposed surface of 18,9 cm2, and a transfersurface of 9,4 cm2, for a volume of 0,25 ml. I think that should do the job of evaporating the stuff... :D

I intend to use the Regner valve as control valve, it has the possibility to shut off the gas flow and thus kill the flame, although Regner states it should not be relied on to have a complete seal.
My intention is to have a 40 mm brushless fan in the boat, that automatically starts when the controlvalve is in the fully closed position, so in case of a shutdown, outflow is minimized and any accumulation of gas is vented out. That should keep things safe enough until the boat is retrieved.
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Re: Liquid gas feed to burner...
« Reply #18 on: October 31, 2024, 03:25:44 pm »

Bonjour,
About safety RC gas valve, mandatory for me, I find steam manufacturers ones very expensive so I now use an alternative 4 times less expensive  :-))
https://youtu.be/egl3ngBwsVM  installed like this https://youtu.be/y6b9mqO95Uk
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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #19 on: Yesterday at 06:31:08 am »

WRT valves for safety systems: Anyone know a good source for tiny solenoid valves suitable for handling liquid gas?
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Re: Liquid gas feed to burner...
« Reply #20 on: Yesterday at 09:37:34 am »

Hi Gents,

Anybody having any experience with this? I see great advantages, and a few issues/dangers that I think can be controlled remedied.

For all clarity, my intention is NOT to feed the fuel to the burner nozzle in liquid form...
My intention is to extract the fuel in liquid form from the tank, and evaporate it en-route to the burner control valve.

The reason for this is simply put, to relocate the evaporation process from the tank to "another place, not being the tank".
The advantages I hope to achieve are:
-Constant temperature of the tank (no or negligable evaporation in the tank, thus no pressure drop)
-Constant composition of the mix in the tank (no "destillation effect" changing the ratio between propane and butane over time)
-Connected to this, no more need to either blow off the tank before filling, or run the boat until empty to prevent butane saturation, a half full tank can be replenished without effect on composition.

-liquid fuel extraction also means sloshing has no effect, therefore the tank can be filled to a higher level.
-elimination of the need for tank heating ("large" energy consumer if done electrically, in my case a significant extension of RX battery duration).

The downside is that either a double fuel feed (gas and liquid) are needed in order to start up on vapour, then switch over to liquid once the evaporator coil is hot, OR the need for temporary external heat during the start-up phase.
I am probably going to try the latter option, since I don't want to add a 2nd valve to my gastank.


As said, anyone having experience with this type of set-up, any do's or don'ts or things I overlooked?

Thanks in advance,

Bert


What you are describing is a Saito burner.
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JimG

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Re: Liquid gas feed to burner...
« Reply #21 on: Yesterday at 12:03:51 pm »

WRT valves for safety systems: Anyone know a good source for tiny solenoid valves suitable for handling liquid gas?
Check out the suppliers for model jet turbine engines, these use small solenoid valves for their fuel, kerosene in their case  but should still work with gas as the fuel is generally under pressure from the pump.Can't help with suppliers in the Netherlands but UK sources are Motors And Rotors and Turbine Solutions. Valves are normally 6V operated.
Jim
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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #22 on: Yesterday at 12:21:52 pm »


What you are describing is a Saito burner.

Is it? If so, I was unaware of that...
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1967Brutus

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Re: Liquid gas feed to burner...
« Reply #23 on: Yesterday at 12:22:47 pm »

Check out the suppliers for model jet turbine engines, these use small solenoid valves for their fuel, kerosene in their case  but should still work with gas as the fuel is generally under pressure from the pump.Can't help with suppliers in the Netherlands but UK sources are Motors And Rotors and Turbine Solutions. Valves are normally 6V operated.
Jim

Thanks for that info. I was not aware of that. I'll look into it.
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Re: Liquid gas feed to burner...
« Reply #24 on: Yesterday at 03:24:26 pm »


Hello !
One try I did about some years ago. With a small tank and no gas line to initiate the burning .  The gas is cooled down after the burner to enter into the gas attenuator.The video speaks by it self.,: small tank , stable flare , lot of heat and no ice covering the wall .
https://youtu.be/_1DNVCx6zgI?si=23jHEIYRes-YRPmW



Below I show an early installation with a gas line to start the burning. Switching on the liquide line is done without any disturbance.
Photo

The last video , I explain to our friend Giovanni (R.I.P)  , why In close boat when I cannot remove the gas tank , I favor filling up with a bleed  off line extended with silicone tube to let the gas escaping outside the boat.  This si just a matter of common sense not to let any leak inside the boat during the fill up.

https://youtu.be/VKvPsVlZ1sw?si=eQD772-SgQq2-95e
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