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[1967Brutus]

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

[1967Brutus]

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.

[DBS88]

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.

[1967Brutus]

Thanks for the compliments!

As for honesty, I'm in it for the learning, both incoming and outgoing, not for the ego...
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.
 

[1967Brutus]

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.

[1967Brutus]

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.




(yes... the boat is in operation here... No smoke, no steam, no oil traces...)

[rhavrane]

Bonjour,
And no whistle 

[1967Brutus]

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...

[KBIO]

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 ! Thanks for sharing your experience, I'm going to wait until it's 20°C before going to the pond ! LOL![/color]

[1967Brutus]

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 ! 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

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...

[1967Brutus]

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.

[1967Brutus]

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.

[KNO3]

Sounds good. It would be nice to see some good photos of your current set up.

[1967Brutus]

I am not the best of  photographers, but here's an attempt:



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:


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.

[KNO3]

Thanks!

[1967Brutus]

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.


First tests (with less slope) were promising, will report back as soon as the next testrun is done.

[1967Brutus]

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.

[1967Brutus]

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

[KBIO]

Hello !
As per the book ! 
Can we see more of the supoly boat carrying a riser (looks like)  ??

[1967Brutus]

Hello !
As per the book ! 
Can we see more of the supoly boat carrying a riser (looks like)  ??

That's an old Robbe Rembertiturm, I have some footage of that, Facebook

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[KBIO]

I did not know that Robbe offres kits for supplies boats.

[1967Brutus]

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

[1967Brutus]

About 10 months, maybe 20 runhours and therefore approx 2 kilos of gas through the system, I can only say that the system basically works flawless, with a few operational notitions (things to consider):

1-I have had ONCE in this period that the burner flamed out due to wind, which is unrelated to the liquid feed. It is a thing to consider because you really do not want liquid fuel to reach the burner, not even when it is extinguished, but the risk is minimal, because due to my evaporator being on the chimney, which retains a fair bit of heat, it takes quite a while before liquid passes the evaporator. Something to keep in mind, but not a big risk.


2-preheating the evaporator is a bit of a thing in windy conditions. I need to find a better burner for that, because the pencil-torch that I am using easily flames out in wind.
It IS most definitely possible to get the system going without preheating the evaporator, but that takes a LOT of attention and I really can NOT reccomend doing that UNLESS there is a separate vapour valve on the fuel tank.

3-The final thought is that gas apparently contains some dissolved "not gas" which as far as I can tell are heavy hydrocarbons carried over from the refining/destilling/cracking process where crude oil is refined to produce LPG. With vapour feed, these longchain hydrocarbons typically remain in the bottle or tank, and will not very rapidly cause issues, but with liquid feed, these are carried with the liquid into the evaporator, where they will precipitate.

I have had blocked burner nozzles before, which is not a really big issue, a nuisance when pondside, but an easy fix with the tiny high power U-son cleaner.
Last outing I noticed that the burner control, which has been really rocksteady w.r.t. burner setting at full ahead, all of a sudden ran a bit higher.
If steam demand does not change, that means effective burner output also does not change. So if burner control sees the need to increase, it means there is a restriction somewhere.
Cleaning the nozzle did not cure the issue, and the issue worsened the very next outing to where I could barely hold "half ahead".
So dismantling the fuel lines, it showed the line from tank to controlvalve (which also has the evaporator coil in it) to be near completely blocked, and I had to FORCE brakecleaner through to open it back up again. In all fairness, once the brake cleaner managed to reach the blockage, it dissolved the crud in seconds (which is the reason for me thinking the issue is not filterable dirt but long chain hydrocarbons) and all in all it was not a big job, but trying to connect a spraycan to a fuel line with cone-couplings has its challenges...

I have no idea whether this issue can be prevented with a filter in the line, since I am fairly sure, the "dirt" is in solution in the liquid-state fuel, so it will pass a filter in the liquid line, and it is not there in the gaseous state fuel, so a filter in the gas line also probably won't do much good. So I'm not yet considering filters.

It is very possible, that given the fact that prior to running liquid feed, at least some 10 kilo of fuel has been evaporating in the fuel tank, which, I assume, would cause residue to precipitate in the tank. Precipitation that back then built up, but now possibly went back into solution and migrated to the evaporator.
So maybe from now on this issue will be at least a less frequent issue.

[1967Brutus]

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.

On this issue, I can report having seen approx 40 deg C on hot summer days with strong sun.
Not sure where the safe limits are, but I could not really notice this high temperature (and thus fuel pressure) in the automated burner control settings.
At best I had to reduce the manual valve for pilot fire a bit, but apart from that, nothing really changed.
I am thinking of removing the black paint from the tank, to reduce heat absorption from radiation (sun, hot surfaces in the boat, etc).

[DBS88]

Thank you for the update and for the thorough way you have developed this approach, there is much to learn from what you have achieved, well done.