Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Steam => Topic started by: 1967Brutus on October 28, 2024, 12:40:52 pm
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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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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 (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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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 (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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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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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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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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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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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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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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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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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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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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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 .
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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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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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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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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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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 (http://www.microcosm-engine.com/m26d-gas-burner-for-live-steam-boilersnew-p-228.html)) 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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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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WRT valves for safety systems: Anyone know a good source for tiny solenoid valves suitable for handling liquid gas?
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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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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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What you are describing is a Saito burner.
Is it? If so, I was unaware of that...
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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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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 (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 (https://youtu.be/VKvPsVlZ1sw?si=eQD772-SgQq2-95e)
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I favor filling up with a bleed off line extended with silicone tube to let the gas escaping outside the boat.
Thanks for the videos. They are clear and enlightening.
Not letting gas escape INTO the boat, in itself is clear, but... I have so far never seen the need for letting gas bleed off during filling?
I like those snap-on couplings... who sells them? Haven't found them yet.
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Bonjour,
These ones ?
- http://fr.rs-online.com/web/p/coupleurs-rapides/6671784/?sra=pstk (http://fr.rs-online.com/web/p/coupleurs-rapides/6671784/?sra=pstk)
- http://fr.rs-online.com/web/p/coupleurs-rapides/6671778/?sra=pstk (http://fr.rs-online.com/web/p/coupleurs-rapides/6671778/?sra=pstk)
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Hello !
Filling up a gas tank with no bleed off is like filling up blind. You never know if it's full or not , above all with the connections supplied . A bleed off with a plunger inside the tank at about 15/20 mm from the top is a clear indication of the tank being full when the liquide spits outside.... the boat ! ok2 and it leaves a void space for safety .
I get those push/pull connections for a fair price ,compared to what is proposed in some other places , in Germany:[size=78%]
https://www.bengs-modellbau.de/en/Quick-coupling-Nw-2.7/7021 (https://www.bengs-modellbau.de/en/Quick-coupling-Nw-2.7/7021)
[/size](you have plenty informations and suppliers all over the world , here: https://modelismenavalvapeur.forumactif.com/ (https://modelismenavalvapeur.forumactif.com/) )[size=78%]
Whatever I built , I keep my standards to :
- 6,75 mm for steam and 5,50 for gas. I keep BA in BA as I have the tap & die for it , but as I am always doing tests , I am swapping engines or boilers and standard threads make the thing easy.
I'm gone for a few days ! Have fun and "Steam up"!
[/size]
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Thanksfor the info, guys!
Feel a bit silly, since I have bought from Bengts before, the grafisil balls for my safety valve repair... Guess I did not look properly, huh? Duh...
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Filling up a gas tank with no bleed off is like filling up blind. You never know if it's full or not , above all with the connections supplied . A bleed off with a plunger inside the tank at about 15/20 mm from the top is a clear indication of the tank being full when the liquide spits outside.... the boat ! ok2 and it leaves a void space for safety .
Makes sense... My tank is removable, I weigh, so I know what is inside...
Raphaël showed a gas tank with a level glass... I guess that would be my preference in case weighing is not an option, but your solution works as well.
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For a while I used to build gas tank with glass gauge . But I quickly realized that it not very handy to see them when inside the boat and that the tube glass is very fragile .
They end up cracking and leaking (always at the bad time) and the O'ring getting old ends up by leaking.
I then did some with a polycarbonate window , which is a lot stronger and safer , but still , it is difficult to check the level when inside the boat.
I must admit that , even if I don't use them anymore , it is lovely to have it.
Just do what you like, as long as you like it , that's make the life brighter and the steamer happy !
:-))
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Just do what you like, as long as you like it , that's make the life brighter and the steamer happy !
:-))
:D It's not a matter of choice... I only have ONE gastank, and it's not fixed in the boat :D :D :D
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Hermann Echtdampf sells a full set for converting Regner gas tanks to quick coupling, including the valve and pipe for refill from a commercial gas canister:
https://www.echtdampfwelt.de/gaseinfullsystem.html
The parts can be bought separately as well:
https://www.echtdampfwelt.de/echtdampfshop/gasarmaturen.html
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Out of curiosity I have now added a pressure gauge to the refillable gas tank so that we can see the pressure in the tank at the start and also whilst the burner is running. The guage is connected to the valve that supplies gas in the gas phase. In the video, the burner is running completely from the liquid phase valve. My workshop temperature is about 20C, the pressure shown at the start is 45psi or 3Bar. The pressure remains constant through out the test, after a couple of minutes gas valve is opened further and the burner runs near to its maximum with a 0.5 gas jet, the pressure remains at 45psi or 3 Bar, the gas tank does not get cold, no condensation forms, and no icing on any of the pipework. The flame is a good steady flame.
https://youtu.be/4haodDkh0M8?si=yuy8hr9RpY3H7tMf
We now know that the pressure in the system is 45psi or 3 Bar which is higher than the 2 Bar that I have seen other video's of liquid phase gas being used.
The figure of 3 Bar or 45 PSI in my tank at 20C was worrying me, since other videos show 2 Bar, I wondered if my gauge was not working properly? I did some further research and it appears from this chart that 3 Bar is about right.
I hope this further information is useful to your project
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Bonjour,
For fun, using the usual gaseous phase with a large burner : https://youtube.com/shorts/RPYHMExjdIo
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Out of curiosity I have now added a pressure gauge to the refillable gas tank so that we can see the pressure in the tank at the start and also whilst the burner is running. The guage is connected to the valve that supplies gas in the gas phase. In the video, the burner is running completely from the liquid phase valve. My workshop temperature is about 20C, the pressure shown at the start is 45psi or 3Bar. The pressure remains constant through out the test, after a couple of minutes gas valve is opened further and the burner runs near to its maximum with a 0.5 gas jet, the pressure remains at 45psi or 3 Bar, the gas tank does not get cold, no condensation forms, and no icing on any of the pipework. The flame is a good steady flame.
https://youtu.be/4haodDkh0M8?si=yuy8hr9RpY3H7tMf (https://youtu.be/4haodDkh0M8?si=yuy8hr9RpY3H7tMf)
We now know that the pressure in the system is 45psi or 3 Bar which is higher than the 2 Bar that I have seen other video's of liquid phase gas being used.
The figure of 3 Bar or 45 PSI in my tank at 20C was worrying me, since other videos show 2 Bar, I wondered if my gauge was not working properly? I did some further research and it appears from this chart that 3 Bar is about right.
I hope this further information is useful to your project
Too bad the noise of the burner near completely drowns out your voice and makes your comments unintelligeble, but absolutely a very useful and inspiring video.
the 2 bar might be the result of using a filling bottle that also has been feeding a burner in the gaseous phase some previous occasion, and the propane content of the mix in that bottle having lowered a bit.
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Bonjour,
We are supposed to use a pressure of about 800g / 10 - 15 PSI to the burner and a gas regulator needs a gaseous phase, this means that, in a liquid phase mount, these parameters should be taken in account,
I say that because for me, a gas regulator is a securing accessory as it is not mandatory in the practice of model boats I mean !
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Helo !
A very accurate observation, as the propane %tage decreases more rapidly. But if you look at the chart above, a difference of 5°C justifies the pressure difference.
Many burner tests are carried out at room temperature, and in a workshop, the temperature is more often 15°C than 20°C, especially in winter.
This means that DS88's reasoning is correct, given the chart.
Below is a graph I propose on my forum , showing how propane behaves during burning and why the pressure in the tank drops.
Note that when the tank level is at the middle , there is 25% Propane for 75% Butane .The propane would only propel the mixture, the two calorific values being more or less the same.
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Bonjour,
We are supposed to use a pressure of about 800g / 10 - 15 PSI to the burner and a gas regulator needs a gaseous phase, this means that, in a liquid phase mount, these parameters should be taken in account,
I say that because for me, a gas regulator is a securing accessory as it is not mandatory in the practice of model boats I mean !
Not sure if I understand this post properly...
I understand what you mean by a "securing accesory".
I mean, how does it improve safety?
I agree on the constant pressure, but in my opinion, "liquid phase feed" allready provides a significant improvement on the stability of the fuel pressure.
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Bonjour,
Sorry, my French is better than my English to give my opinion, would it be because I am French ok2 ?
What I wanted to say is that for me I specify, the gas regulator is a very useful accessory in terms of safety.
In fact, in the event of the boat being blocked unexpectedly in the middle of the lake, as has already happened to me, a regulator stops the pressure increase and the consumption of steam, which leaves much more time to carry out a rescue and avoids any risk of possible deterioration of the boiler.
It is not mandatory and I feel much more safe with one on my steam plants.
My friend Google, I like using when I have a doubt or a lack of vocabulary translated "sécurisant" by "secure" because I thought that "comfortable" was not appropriate to translate my opinion.
Counter example, for the "Anton trophy", we operate at 8 bar (+/-120 PSI) max and there, no regulation, all the heat power is needed and our lonely safety accessory is the RC safety gas valve : https://youtu.be/IzHLYp4lXtM (https://youtu.be/IzHLYp4lXtM) (The winner, "Ky" as a more efficient boiler than mine as we have the same speed machines https://youtu.be/pxjvgliqmuI (https://youtu.be/pxjvgliqmuI) )
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Thanks for the explanation. Languages and translations can be tricky at times.
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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.
I am coming back to this, for reason that I opened my gastank today to check the possibility to install a riser tube under the gasvalve (which is no problem).
When doing so, I also measured the exact volume of the tank by filling it with tapwater (measured volume 135 ml) and I checked with a light before filling if there was any debris inside.
I emptied the tank via a coffee filter to see if there would be any debris coming out with the water. I found none. Flushed it 3 times with destilled water, same procedure, there was absolutely NO debris in the tank whatsoever.
About 5 kilogrammes of gas have been evaporated in that tank, if there would have been ANY dirt in the gasbottles that I use for filling (I have used 3 different brands, the bulk of it Rothenberger, but also a few no-brand generic bottles) it would have collected in the tank.
Therefore, I absolutely do not believe in dirt coming from those bottles, and any dirt formed, therefore HAS to originate from overheating/decomposing in the evaporator.
I am currently modifying, using a temporary coil of 2 mm ID (3 mm OD) because I do not have any other suitable material.
Gas tank has its riser pipe, and appears to be gas-tight. So far, so good.
Coil will be experimental-only-aesthetics-later...
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Well...
I think I overestimated the Regner gasvalve's abilities...
I have a HUGE fire now, and the regner valve barely controls it... Even with the engine full ahead, and the gas regulating valve at minimum, burner pressure was in no time over 2 bar (control setpoint 1,5 bar).
Now it is very possible that I accidentally opened the pilot regulating valve.
Anyway, with a bit of care, it IS possible to fire up without a vapour circuit, and despite the humongous fire, and the heating deactivated, the fuel tank picked up temperature fairly quickly to 28 degrees C.
So THAT part of the game works.
A second, slightly less nervous (me) run, allowed me to pay a bit more attention, and this revealed that the controlvalve DOES control, it simply needs a bit of readjustment.
Apart from that, it worked fabulous! The tank remained constant in temperature without heating, the fuel pressure, judging by the virtually total lack of correcting action by the pressure control was absolutely constant from the very beginning till the last 30 seconds.
When fuel ran out, in about 10 seconds the burner controller went from about 20% to 100%, the flame reducing, and about 10 seconds later the flame went out, just like that.
Video:
First run with experimental liquid gas feed (https://www.youtube.com/watch?v=Hpia6UpqiGA)
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I remembered, that when I first received the valve, and used it with an unheated gastank, about a year and a half ago, I was not impressed with maximum fire, so I shifted the lever a bit over the control spindle.
Back then I was running a cold tank and thus lower fuel pressure.
I restored original calibration of the controlvalve, and now it simply works. I had to set a pilot fire adjustment to prevent the burner from extinguishing, but other than that it now works like a charm.
Rocksteady pressure control, and from full tank to empty, the burner position does not change if the steamthrottle is not moved.
I am very pleased.
Of course, I need to re-do the entire system, because it works in the test-conditions (indoor, no wind) but it looks ugly as heck.
I have a few ideas for that, but if I can do that, remains to be seen.
The start is relatively simple: Set RC valve to manual, and set it to full open, liquid valve closed. Hold a pilot fire at the funnel, and very carefully open the liquidvalve until the fire catches. Manually keep the fire a bit low. Within about 15 seconds, the RC valve can be closed. If fire responds, the liquid valve can be carefully opened further. Raise steam on a tempered fire. Onc pressure is in range, set RC valve to auto.
https://www.youtube.com/watch?v=TZ4jjKwckxw
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Rearranged the evaporator coil to make use of heat transfer through metal-to-metal contact instead of the hot gasses.
Reasons for doing, first of all, the first experimental set-up really looked like crap, second, the coil was located OVER the flue gas outlet.
A gust of wind would mean that the hot outflow would be pushed aside, not only robbing the coil of its heatsource, but maybe even actively cooling it. Dangerous!
The coil now being located lower, and in direct metallic contact with a guaranteed hot metal conduct should ensure a more stable heat supply, of still an acceptably low intensity.
How it looks now:
(https://www.modelbouwforum.nl/attachments/20241112_084248-1-jpg.599427/)
To me, this is aesthetically acceptable.
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Well done and thank you for sharing your work with us, we can all learn from what you have achieved.
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Bonjour,
Nice job indeed to my opinion, furthermore it fully justifies the French expression "Usine à gaz" ;)
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About 5 kilogrammes of gas have been evaporated in that tank, if there would have been ANY dirt in the gasbottles that I use for filling (I have used 3 different brands, the bulk of it Rothenberger, but also a few no-brand generic bottles) it would have collected in the tank.
Therefore, I absolutely do not believe in dirt coming from those bottles, and any dirt formed, therefore HAS to originate from overheating/decomposing in the evaporator.
Yeah, right! Me and my big mouth... Spent about an hour messing about and swearing, not understanding why the darn thing would not light.
Found the nozzle blocked.
Does only confirm my conviction that there is no dirt in the gas though, because how else would I be able to burn 5 kilo of gas without any problems, have a squeaky clean fuel tank, but still within 2 runs after changing to liquid fuel feed encounter a blocked nozzle?
My best guess is that I soldered the fuel lines with resin core tin, and the fuel now being liquid in the line, dissolves the resin.
Anyway, after U-son cleaning, the thing ran again, and the new evaporator is easy to use.
I lighted the burner with everything cold, which is doable if being done careful, but I think the new standard will be to heat the funnel for 10~20 seconds with one of those tiny burners (I belive they are used to make "crème brulé" or something, anyway, barely bigger than a cigarette lighter and a nice little flame. Heat the evaporator, open the fuel and light the burner. A bit of assist at the evaporator for the first 10 or 20 seconds, and things should work all on their own from there.
And they do:
https://www.youtube.com/watch?v=VbxQ-J2g41M (https://www.youtube.com/watch?v=VbxQ-J2g41M)
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Well done and thank you for sharing your work with us, we can all learn from what you have achieved.
Thanks! It seems to work really well, but I have to still get used a bit to the slightly different behaviour at start-up and initial raising steam.
But the constant, and much higher fuel pressure is a real blessing. The fact that the RX battery load has reduced by about 65% is marvellous (and was the primary goal), but the stability of the system is really amazing. So much so, that there literally is ZERO indication of fuel remains decreasing, AT ALL...
It just goes and goes, and all of a sudden, simply the burner control goes to full within a few seconds and that's it...
In the old situation, I saw a fairly constant steam pressure, but over the duration of the run a gradual increase of the burner control, due to the dropping fuel pressure. That gave me a crude indication of fuel remaining. Now I REALLY have to fill the tank to a prescribed amount and use the timer, or I am screwed. :D :D :D
Oh, well, there's a downside to everything I guess... :p
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Bonjour,
Nice job indeed to my opinion, furthermore it fully justifies the French expression "Usine à gaz" ;)
I had to look that one up, but.... yes... it does, doesn't it?
Yet, while by now over the course of a year the internals of the boat resemble a plate of spaghetti, the liquid feed system actually is extremely simple, and way easier to use than I expected...
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Last one, a full start-up from cold, and then I will shut up about it. System is simply fully operational, no ifs or buts.
As you can see, it basically is absolutely no more hassle than a conventional gas system. Mind you, it is way easier to make really stupid mistakes, like allowing liquid gas to pour into the boat, but if the preheating of the coil is done properly, that functions as a barrier of sorts.
The 3~4 minutes that the camera was paused, there was absolutely nothing more to see OR to do, just a low setting burner heating up a boiler.
Hope you like it.
https://www.youtube.com/watch?v=sTtwlDO8E9E
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I was reading through the thread, Checking if I missed any of the advises given, if there would be anything that could possibly deviate, recaps, etc etc.
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. (1)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.
(2)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!
(1) It turns out to be possible to start the burner system "cold", if I am VERY (and I mean EXTREMELY) careful. My fuel shut off valve does not really allow for minimal flowrates, especially not in liquid phase. A way to start the cold setup is to open the valve very carefully until I see condensation on the liquid line, and IMMEDIATELY close it, then ASAP light the burner. Heating up can then be controlled by observing the flame and very briefly give it a shot of fuel when the flame size shrinks.
In order to do this, the RC gas control valve has to be fully open, meaning there is no redundant safety in the system, and it is extrmely easy to make mistakes.
I did it, it IS possible, but I strongly recommend AGAINST it. I had an extinguisher beside me all the time.
With a better controllable shut-off valve a cold start can be done easier, but still, very dangerous. Do NOT do this unless for experimenting only and in a safe environment only.
What however, IF done properly, is absolutely safe, is to preheat the coil before opening the shut-off valve. RC valve can be in a reduced position as in "low fire".
If the evaporator is preheated sufficiently, it will form a "liquid barrier", and the amount of, and rate of opening of the shut-off valve becomes irrelevant: Liquid fuel will enter the line, evaporate at the coil, and from there the vapour meets a strongly throttled control valve. Fuel will pass at an acceptable rate for safely lighting the burner. However, this is a relatively very short term situation, once the coil cools down, liquid can pass, so it is imperative to IMMEDIATELY light the burner, and continue to preheat the coil.
If lighting the fire fails, close everything, and ventilate the boat thoroughly before again preheating the coil and attempting to relight.
Starting a liquid phase feed burner needs to be a solid ingrained procedure for the operator, taking maybe 40 seconds, but in those 40 seconds no distractions, no interruptions. My latest video showed a huge violation of that principle when my torch refused to fire when I wanted to "after-heat" the evaporator. It also showed nothing really bad happening.
(2)My setup is as follows WRT physical dimensions:Fuel system consists of one single length of appr 80 cm copper tube 2 mm ID, of which appr 20 cm passes liquid fuel into an approc 40 cm long evaporator coil, and then 20 cm of "cool down tubing, where it meets the control valve. From there a 1 mm ID line of approx 15 cm passes fuel to the burner
The liquid part of the system (20 cm tubing, ID 2 mm) contains at best about 0,3 grammes of liquid fuel. At a burner setting for "engine full ahead", this is less than 10 seconds of burning. The fire will actually take longer to extinguish, since upon closing of the valve the liquid remaining in the line, will start to evaporate and drop in pressure, so what you will see is a flame that immediately starts deminishing when the valve is closed, and slowly decline until it dies in about 20 seconds or so.
Even on a completely dry boiler, this will not cause any damage.
I am hard pressed to think of a situation where the flame out delay would be unacceptable, but in case so: a 1 mm ID fuel line can pass an awful amount of fuel allready (400 grammes per hour are no problem at all, flow velocity about 0,1 m/sec). In cases where long liquid lines are inevitable, build them out of 1 mm ID tubing and delaytime will be strongly reduced.
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Thank you for sharing what you have done and achieved, well done, there is a lot we can all take away from your work. The quality of the engineering in your boat and your attention to detail is a credit to you.
Re the blocked gas jet, your honesty about this is appreciated, I too have shared your frustration in trying to find the problem, only to realise that the gas jet was blocked.
As a matter of coincidence, a friend has asked for some work to be done on his boat, at the weekend I fired up the boiler and it had a very weak flame, yes the No5 gas jet was partially blocked, another fitting, a gas attenuator also had a very fine pale residue inside it, which unfortunately didn't photograph. So yes it happens, and it obviously happens using gas in the gas phase, so at ambient temperatures, to such an extent that a reputable manufacturer (Regner) produces and sells gas filters for use with their gas and steam model products, its a very neat unit. I bought one about a year ago but have not yet installed it.
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Thanks for the compliments!
As for honesty, I'm in it for the learning, both incoming and outgoing, not for the ego... :D
I am of course a bit proud of the achievements, but not to the point that I keep goof-ups to myself. No learning there.
When I had my blocked jet the other day, it was a bit weird, in that I could not get the gas to flow at low burner setting, but when turning to full, a short burst popped through after which the jet blocked again.
Impossible to see what was in it, but trying to clean it with a Q-tip gave what apeared to be dark and gooey.
I sincerely think it was resin from the Tin I used for soldering the fuel line.
Went through 2 more full tanks, not filmed, not reported on since there was nothing to report. Meaning no more dirt.
I will, trust me, report the next time a jet blocks, including the runtime and amount of gas that went through the nozzle.
I have an idea for a better design evaporator, that should make cold starts easier, consisting of a relatively short and stubby barrel (appr 5 mm diameter, 5~6 cm length) placed vertical in the wall of the smokestack. Fuel lines 1 mm ID, fuel entering at half height, exiting at the top.
Should be a visually "clean" set-up and very easy to start without any external heat.
It will probably take 1~2 weeks to order material and start fabricating.
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A week of 12 hr shifts later, coming home straight after the last shift, the proof of the pudding is in the eating as they say.
Procedure check. Conditions, unheated test room (bathroom), gastank at 15 degrees (ambient), touch over 30 grammes of gas, check if the firing up procedure works, so there we went:
Gas control valve in starting position (approx corresponding with half ahead, which is a fairly conservative little fire).
20 seconds of preheating the coil, crack open the liquid valve and light the fire, 20 seconds of supporting heating of the coil and that should do it. Which it did.
There is a little instability in the first few minutes, a small but clearly noticable rhytmic surge in the fire every 2~3 seconds,probably this is a bit of gas re-condensing after the coil in the still cold vapour line. It is really minor, and I think it is nothing to worry about. It dissapears before steam is raised, when the vapourline warms through.
Once steam is raised, immediate stability, but the effect of tank temperature is noticable in the equilibrium position of the gas control valve.
I noticed that during this test the gastank also stabilized at about 25 deg C, and I am not sure where this 25 degrees tanktemperature is coming from, to be honest... A bit curious where that will end in summer conditions..
Saturday first test on open water, most likely probably going to be pretty cold, so that will be a real operational stresstest for the set-up.
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Today was THE day:
About 5 deg C, and about 3 Bft, so quite cold and due to the wind most likely a fair amount of heatloss.
My preheating/ignition burner pretty much sucks, I need to find something better for that.
Despite that, I managed to get the burner lit and the evaporator going (don't ask how) and from there, the system functioned pretty much flawless even in these cold and windy conditions.
I started out with a gas tank that was 6 degrees. noticable significantly less fuel pressure. But the electric heating still present, the tank was in no time 20 degrees, and heat radiation from the engine kept the fuel more or less at that temperature thereafter, since I did not see the tankheating activate anymore once it reached that temperature.
In other words: despite having to look for a better portable burner for preheating and igniting, the system functions flawless, even in these temperatures.
(https://scontent-ams4-1.xx.fbcdn.net/v/t39.30808-6/467758630_8446250935484408_1128008296726535667_n.jpg?_nc_cat=109&ccb=1-7&_nc_sid=127cfc&_nc_ohc=LlXAgajoA3MQ7kNvgHz70Rw&_nc_zt=23&_nc_ht=scontent-ams4-1.xx&_nc_gid=AYLPkbmHAfuRPOBPpFritGf&oh=00_AYDVvuUSK6LtTFiyBwOeyQQWUicaO64GCkwzmwh2a7v0TA&oe=6747B427)
(https://scontent-ams2-1.xx.fbcdn.net/v/t39.30808-6/467866279_8446250945484407_5523179202841699074_n.jpg?_nc_cat=111&ccb=1-7&_nc_sid=127cfc&_nc_ohc=9R2CeUg54C8Q7kNvgEiSzQp&_nc_zt=23&_nc_ht=scontent-ams2-1.xx&_nc_gid=A4tzQz22lu_oSIvl4ZKXLsO&oh=00_AYDwoPXQBG9sFq7VTN1rmVKkAKZ7dKv2u3fzyVKx4iJhBg&oe=6747C3BB)
(yes... the boat is in operation here... No smoke, no steam, no oil traces...)
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Bonjour,
And no whistle <:(
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No whistle...
Not gonna happen...
But I LOVE that liquid phase feed. Thanks to KNO3 who pointed my attention to the possibility of liquid phase feed...
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Hello !
Nice boat and nice test ! :-))
Congratulations for going sailing in that bad weather!
[/size]Probably only a Dutchman can do that ;-))[/color][/size]5°C, that's more or less the boiling point temperature of Butane. Propane is there to help but I presume that during the flowing , the temperature remains very low and unlike the sailing Dutchman, the mixture stays safe at the bottom of the tank ! :}2 Thanks for sharing your experience, I'm going to wait until it's 20°C before going to the pond ! LOL![/color]
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Hello !
Nice boat and nice test ! :-))
Congratulations for going sailing in that bad weather!
Probably only a Dutchman can do that ;-))5°C, that's more or less the boiling point temperature of Butane. Propane is there to help but I presume that during the flowing , the temperature remains very low and unlike the sailing Dutchman, the mixture stays safe at the bottom of the tank ! :}2 Thanks for sharing your experience, I'm going to wait until it's 20°C before going to the pond ! LOL!
Yeah, it was pretty cold, but the upside was: it was the last clubday of the year for the club I was guest, and they had a very hearty pea-soup, and a heated clubhouse :D
On the bolded: The beauty of liquid phase feed is that there is NO (or virtually no) evaporation in the tank itself, and the liquified gasses mix in every ratio and form a stable mix, similar like water and alcohol do.
I started with a fuel tank temperature of 6 degrees, which is fairly noticable in the pressure, but without evaporation in the tank, it is amazing how little heat it takes to raise gas tank temperature (and thus fuel pressure).
In any case, as soon as steam was raised, the entire situation was as stable as a rock.
What was most noticable, was that the engine needed quite some time before the lower gear (crankshaft, crossheads and rods) warmed up, and during that time, the effect of cold lubricating oil was very noticable in a lower top RPM and the engine unwilling to run really slow.
Fuel consumption also was noticably higher than normal. The full filling of 65 grammes of fuel, normally enough for 40+ minutes full ahead, now only lasted 35 minutes.
Meanwhile, I found a very old "Pencil Torch" and I think that thing is WAY more suitable for firing up the burner.
EDIT: just tested it, and it's a bliss...
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With Yves' remark about Butane boiling point in mind, I put the gastank in the freezer until it was below -10 deg C.
Now of course it warms up in the time it takes to place it in the boat and the fuel line being hooked up, but by the time I got to lighting the boiler, it still was -5 deg C.
I had to open the gas control valve significantly more, but the burner did not object to being lighted, and the entire event actually was very predictable.
Preheat evaporator, blah blah and off it went. Since the tank heating was on (it is automatically controlled) the tank steadily rose in temperature, fuel pressure increased, RC gasvalve had to be gradually reduced.
The "pencil torch" works a charm, much easier in use, much safer, one hand operation, stronger flame and at least it keeps going.
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As a follow-up:
I have now been running this system for about 8~10 hours of testing, including out on the pond.
It seems to work OK, and once running, I have so far not seen any undesirable situations (such as flame outs or such).
Most of the time, lighting the burner is pretty straightforward, I have seen once or twice that I had minor trouble getting a stable flame.
The jury is not yet out on that for the cause of this.
One thing that I see, which does not seem to cause any issues BUT puzzles me a bit, is that the burner is large parts of the time surging.
There seems to be some irregular fuel flow going on: liquid fuel enters the evaporator too fast, evaporates rather rapidly, and the pressure surge pushes the liquid back into the tank, and causes also a clearly audible surge in the burner. The burner then continueing to consume gas in its usual rate rapidly allows liquid to enter the evaporator coil and the process repeats itself at a rate of about 1 surge per second or so.
The surging seems to stop above certain fire rates, and mostly occurs at lower burner settings. Sometimes it stops even at low fire but more often, not...
Regardless of surging, the pressure control does not sem to be affected by it.
I am going to stick with this set-up for now.
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Sounds good. It would be nice to see some good photos of your current set up.
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I am not the best of photographers, but here's an attempt:
(https://www.modelbouwforum.nl/attachments/20241207_211604-1-jpg.602441/)
It really is no more complicated than this. Initially, with vapour feed, the fuel line went from tank straight to control valve.
Now, it runs from tank to funnel, wraps around the funnel 4 turns (wound on a slightly smaller core, so the coil is tight around the funnel with firm metallic contact), then continues on to the control valve, with some excess length in order to let the gas cool down a bit.
That is all there is to it. Not visible of course, is the riserpipe in the tank, that changes the fuel feed from vapour to liquid.
Sharp eyes will notice that the original TowerPro servo, which mechanically still was sound but somehow lost its precision and did not always respond immediately either, has been replaced for a digital precision servo intended for 450 size helicopters. A near direct drop in fit, replacement was a 5 minute job. Control stability improved even a bit more (corrections by the servo are now within the mechanical clearance, meaning in a constant speed situation the valve does barely ever move and the fire remains stable. The original servo, much more coarse in its response, would constantly overshoot, and thus "hunt" a bit).
Then this silly old thing is a very important tool for the entire operation:
(https://www.modelbouwforum.nl/attachments/20241207_211827-1-jpg.602442/)
These things were everywhere in the 1990's, but nowadays, I guess you can still buy them, but you have to look for them online.
I had this "creme Brulee burner" which was awful: Once the burner was hot, it would refuse to relight until it had cooled down. Very inconvenient if for whatever reason I would (accidentally) let go of the trigger halfway the preheating, or worse, at igniting the burner, because for safety reasons, once the burner is lit, some additional "afterheating" is advisable.
So far, I have never seen any real issues upon faillure to afterheat, but alas, better safe than sorry.
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Thanks!
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As a follow-up:
I have now been running this system for about 8~10 hours of testing, including out on the pond.
It seems to work OK, and once running, I have so far not seen any undesirable situations (such as flame outs or such).
Most of the time, lighting the burner is pretty straightforward, I have seen once or twice that I had minor trouble getting a stable flame.
The jury is not yet out on that for the cause of this.
One thing that I see, which does not seem to cause any issues BUT puzzles me a bit, is that the burner is large parts of the time surging.
There seems to be some irregular fuel flow going on: liquid fuel enters the evaporator too fast, evaporates rather rapidly, and the pressure surge pushes the liquid back into the tank, and causes also a clearly audible surge in the burner. The burner then continueing to consume gas in its usual rate rapidly allows liquid to enter the evaporator coil and the process repeats itself at a rate of about 1 surge per second or so.
The surging seems to stop above certain fire rates, and mostly occurs at lower burner settings. Sometimes it stops even at low fire but more often, not...
Regardless of surging, the pressure control does not sem to be affected by it.
I am going to stick with this set-up for now.
Currently working on this issue. It appears that it has to do (at least in part) with the physical layout of the fuel tubing: In my particular case, the last part of the fuel line entering the coil ran horizontally. In itself this should not really be an issue, but the thing is that copper conducts heat. So the last few cm before entering the coil, that pipe is allready warm, and evaporation starts at some distance before the coil.
This part running horizontally. Vapour bubbles want to rise, liquid wants to fall, but in a horizontal pipe this is not possible.
So any evaporation in this horizontal part WILL push liquid into the hot coil, where it will flash, leading to a pressure surge, causing not only a fire surge in the burner, but also a pushback of liquid back to the tank. No liquid in the evaporator means no evaporation, and the burner still consuming gas, the liquid then rushes in towards the coil with some velocity, and the process becomes repetitive.
I have now bent the fuel tubing such that there is a continuous upwards slope. It's not pretty, but function over form anytime.
(https://www.modelbouwforum.nl/attachments/20241211_103548-1-jpg.602773/)
First tests (with less slope) were promising, will report back as soon as the next testrun is done.
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Most definitely results, but mixed...
Minimum fire, stability has noticably improved, and setting for minimum fire could safely be lowered.
3/4 fire and above, absolutely stable fire, full fire pleasantly "roaring".
Around half, surging returns, but it is clearly less pronounced than before. Less regular also.
Returning to low fire (manually, therefore rapid closing of gas valve), there is a bit of initial instability, but on the automatic control, when valve movements are a bit more gradual, this seems less pronounced.
I'll be uploading videos later.
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Today another "never done before": It was 5 degrees outside, never run the boat in this kind of weather, ever.
The pencil torch (which most likely was the last time refilled more than a decade ago) struggled a bit, but despite that, as well as the fuel pressure being noticably lower with the tank at only 8 deg C, 30 seconds of preheating the chimney was enough, support heat after lighting the boiler turned out not necessary.
Pencil torch in the left hand, transmitter to the right of me, flame at the chimney top, open the liquid valve and straightaway opening the gas control via TX, the fire lit and I had a stable fire straightaway.
Surging occurred at certain throttle positions, but it was so minimal that it was barely audible.
Boat ran perfect for about 50 minutes, due to the low ambient temperature, fuel consumption slightly higher than normal (fuel prssure occurred appr 30 seconds before the fuel timer ran out, which is not bad considering the timer is set at 33,5 minute), but other than that extremely stable, even when running several minutes continuous dead-slow.
Saw the tank heating active during raising steam, but once it stopped, it did not reactivate. In other words: this way of evaporating the liquid gas really works like a charm.
Couldn't be happier...
https://www.youtube.com/watch?v=h_n_wdPw9kU (https://www.youtube.com/watch?v=h_n_wdPw9kU)
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Hello !
As per the book ! :-))
Can we see more of the supoly boat carrying a riser (looks like) ?? ok2
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Hello !
As per the book ! :-))
Can we see more of the supoly boat carrying a riser (looks like) ?? ok2
That's an old Robbe Rembertiturm, I have some footage of that, Facebook (https://www.facebook.com/100003496789015/videos/pcb.8571285592997915/576103365016338)
Facebook (https://www.facebook.com/photo?fbid=8571279806331827&set=pcb.8571285592997915)
Facebook (https://www.facebook.com/photo/?fbid=8571279986331809&set=pcb.8571285592997915)
Facebook (https://www.facebook.com/photo/?fbid=8571280146331793&set=pcb.8571285592997915)
Facebook (https://www.facebook.com/photo/?fbid=8571280292998445&set=pcb.8571285592997915)
Facebook (https://www.facebook.com/photo/?fbid=8571280442998430&set=pcb.8571285592997915)
Facebook (https://www.facebook.com/100003496789015/videos/pcb.8571285592997915/1112782256910152)
Facebook (https://www.facebook.com/photo/?fbid=8571280652998409&set=pcb.8571285592997915)
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I did not know that Robbe offres kits for supplies boats.
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I did not know that Robbe offres kits for supplies boats.
They did... a LONG time ago... I think Rembertiturm was a kit from the late '80's, early '90's