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[Klunk]

Right, down the lake today (yes it was snowy and cold!), and I thought lets get the steam up.........problem could not keep pressure in the boiler due to it being so cold. Tried  to have the gas mix on full, this was ok at the lakeside where i could agitate the can (BLUE PROPANE BUTANE MIX), but as soon as was on the lake I could not keep the boiler pressure up to make more than a minutes headway, without having to throttle off to let the pressure build up again. Is there a way of keeping the gas bottle warm so as not to let it freeze ( i have the same problem during warm weather but to a lesser extent).

Also the boat has a gas jet burner, would it be worthwhile to  get a ceramic burner and if so where from????

[Underpressure]

If the weather where you are is anything like it is here then you're a brave man. We had max temp of 3 degrees and a freezing cold wind blowing all day. These are pretty much the toughest conditions for sailing a steam boat as everything is against you.

To answer: Yes you can heat the gas tank. There are some German made tanks that actually have a pipe through them which is plumber into the exhaust of the engine, other people have some sort of close fitting heat transfer device from the condenser to the gas tank. In one of my boats I have the condenser standing on a brass plate which the gas tank also stands on and on another I have the gas tank and boiler mounted on a common brass base plate, with two thick copper spacers fitted to make contact with both the base plate and the bottom of the gas tank.

Fitting a ceramic burner will also help as they require less gas. It is the transfer of the liquid gas from the tank to the burner which causes the drop in temperature, so the less gas that is used the less everything cools down. There are several sources of burners, it all depends what boiler you have. Clevedon Steam (ebay shop), Bruce Engineering, Mac Steam, Forest Classics just to name a few can all supply ceramic burners and if you look in a plumbing supplier, you will find some very useful pipe reducers, which can be used as adaptors  if you need one.

Neil

[Klunk]

thanks will look into this all over christmas!!!! PS I rang round to get a few others down so I could play!!!!!!

[Underpressure]

There are several threads on this forum about gas tanks and heating them, have a search and see what you can find.

You must have some very hardy mates 

Neil

[Bunkerbarge]

I had a steamer going at the pond side in sub zero temperatures this morning but the pond was frozen over and so couldn't go on the water.  The set up, a Cheddar Boiler and Puffin took a bit of getting going but the gas tank is actually relatively close to the boiler and so conduction of heat through the gas supply pipe warms the gas tank slightly.  The trouble is that until you get some pressure on the gas tank the flame is very poor and you are constantly blowing out the flames that emit from the air inlet holes at the base of the boiler.  

The following are all worth considering to help though:

Pre-warm the tank by either putting it inside your coat or dipping it into a cup of hot water from a vacuum flask.

Pre-warm the boiler by filling it with hot water from a vacuum flask.

Try to keep the model warm by keeping it indoors until you leave for the pond.  Today I kept the model in a van overnight so the model was cold and the filling water actually had ice on the surface of the water bottle.  No wonder it took a long time to get it all warmed through!!  Something to remember for me!!

All these will help to get the plant up and running quickly and then you want to get the model on the water as soon as possible to keep things warm.

Have a look at these gents for a hardy bunch this morning.

http://www.modelboatmayhem.co.uk/forum/index.php?topic=5657.msg209406;topicseen#msg209406

[MONAHAN STEAM MODELS]

There's other options mates. 

While heating the gas tank seems to be the most commonly and obvious method employed for correcting the chilling of the gas tanks, it's not the only option. In fact it's far from the best one. I have been experimenting with different options over the past year to try to find a simple way of eliminating this problem in all climate conditions. What I can tell you from my experiments is that gently heating the gas tanks will only work well in not so cold climates. (Above freezing) For operating in climates close too and below freezing heating the gas tank will not yield the performance results you desire. It will offer an improvement over doing nothing at all, but will not give you the same performance in the colder winter climates that you would see during the warmer summer months.

The nature of Butane/Propane is to turn from a gas to a liquid by chilling the gas (which drops the pressure) or by compressing it under pressure. It's kept at a liquid state by being stored under pressure. (There's more to it than this and I'm sure I will be corrected but please understand I'm just trying to sum this up) When you consume the gas vapor stored in your tank the pressure in the tank drops allowing more liquid fuel to boil off and be converted to vapor, however when this conversion occurs the boiling off of the gas produces a chilling effect which causes some of the liquid fuel to remain in a state of liquid. While operating in warm climates the chilling effects of the tank are kept under control. However as most of you have experienced while operating in colder climates you're fighting a losing battle. Your tank freezes, the pressure drops which in turn affects the burners performance.

So why not stop fighting this battle and start using it to your advantage? I'll explain what I have done.
 
The system that I have developed for use in my personal boilers (which will eventually be offered commercially by my company) is rather complex, so I will spare you and myself by not go into great detail at this time. (Besides this is not meant to be some sort of advertisement.)  I will attempt to sum it up into a simple concept. In both a refillable fuel tank as well as an off the shelf disposable fuel canister the gas vapor is drawn off the upper most part of the tank allowing the liquid to be stored at the bottom. So as I have explained, consuming the vapor will cause the liquid to chill. What I have done is to operate my experimental burners off of the liquid fuel instead of the gas which eliminates the chilling effect altogether no matter the outside ambient temperature. In order for this system to work you will need to convert the liquid back into a gas before it enters the fuel jet in your burner. There are many ways of doing this (hence all my personal experiments) but a simple yet effective way is to make a gas line out of copper tubing shaped like a flat pancake coil of and place it up against the back section of the burner which protrudes outside your boiler. For example: those of you who are familiar with Cheddar's horizontal Proteus boiler know that it has a rather large diameter burner. (I think it's 2 or more inches in diameter.) Well the backside of this burner offers a lot of surface area for this flat wound copper coil to be placed up against.

There are many advantages of using this liquid fuel system which include being able to use every last drop of fuel in the tank, being able to run your models in the dead of winter with the same performance experienced in summer and my favorite, this system when properly designed starts working immediately since you don't have to wait for steam pressure to be raised in order to heat a conventional tank heated by a steam line wound around or place close to the tank (which in my opinion can be dangerous if the heating is not regulated properly). I was waiting to surprise you all with this design of ours but figured some of you could use it now by building your own systems. I expect my competitors will enjoy reading this too. 

[SteamboatPhil]

There was something like that described in model boats a while ago (sorry can't remember when) 

[gondolier88]

Something along the lines of a Lune Valley burner then Nick?

Obviously they were made for kerosene, but used a large surface area to heat that particular petroleum derv', heating to well past critical flashpoint and burning with a white hot flame- however as yuor starting with a far more potent derv' you don't even need to 'raise' to flashpoint as it already flashes at liquid state, you just need to raise the temp' enough to make it into a gas.

The simplest, by far, method i can think of, based on the above burner, is to use the bottom of the firebox of any vertical boiler and make a tray around it. This tray acts as a spill tray to catch any meths that overflows. The meths being collected in the bottom of the firebox- only a small amount mind. The gas pipe could be coiled over the burner a couple of times- making sure that it doesn't block products of combustion path, or be in contact with the flame of the burner as it will chill the flame and cause sooting. This would also heat the gas pipe run along it's length, but wouldn't heat the tank to any dangerous limits.

The second option, which I suppose could be even simpler, that I can think of, is to use a miniature air-sourced heat pump. This would comprise of a 12v computer cooling fan, this would be mounted above the gas tank, which would be located in it's own an airtight compartment. This compartment would have an intake at the bottom (prefarably run from a point near the boiler or engine), at the top a vent would be located of a smaller diameter than the intake and preferably the gas tank would vanes loctited,soft soldered to it (without gas in if soldering of course), increasing it's heating surface by anything upto about 150% I should say.

Alternatively, perhaps we should all start looking at the possibilty of modern technology applied to the burning of a common and cheap commodity- white spirits (turps substitute)- if you burn this normally it smoke with huge volatile discharge. However under strict scientific conditions (yes your right on the balcony of our spare bedroom!!!!! ) I coiled a 400mm (sorry Nick, 16"  ) of 4mm brass tube, about three or four coils at 30mm dia. I capped one end off and left the other end completely open, filling roughly upto the beginning of the coil with white spirit, I heated the coil to a dull red and tipped the tube up over a flame- I got a fireball about 300mm long and a decent, though yellow, flame. This gave off a little smoke, however i'm sure that by introducing secondary air to the termination (a blowlamp basically) then a consistent, controllable, hot flame could easily be produced. This would also negate the need to transport pressurised gas around, and would allow the builder of the boat to construct a liquid fuel tank as large or as small, any shape and any suitable material that they may wish.

Just a couple of ramblings, now, pull them apart guys......

Greg

[ian kennedy]

This is really nothing new, Peter Arnot did the same thing in the 80's published in model boats i seem to remember he used a dip tube mounted on the gas valve stem  to take the LPG out of the gas tank and wound a coil around the burner plate to vapourise it before it hit the jet.

I have used this system for a number of years very successful it is too.

Ian

[Colin Bishop]

There are few things that are new, just those that have been forgotten.

Colin

[Bunkerbarge]

The one main concern with burning liquid gas over the years has been the inability to control the burner by varying the gas pressure according to the boiler pressure, i.e. with an attenuator valve or the good old Cheddar Electronic Gas Valve.

Have you managed to find a way of controlling the burner with using the boiler pressure as an input signal Nick?  If you have overcome that issue you may be on to something.

As it is burning gas from the tank may have disadvantages, especially in cold temperatures, but at least I can control the flame which can save significant amounts of gas and prevents the loss of huge amounts of energy when the safety valve lifts.

[HS93 (RIP)]

two things
 
are you using more than 30% butane ?

and have you still got the gas valve in line?

if so a start would be to get back to basics, remove the GAV and just run as a standard engine , you will get a base then to work from in the future, all you have to do is leave the steam line on  but remove the gas line and take it direct to the tank, as you don't still know if the gav is operating as it should if you cannot get above what was it 40psi in the workshop.
you also need to remember first runs in this weather will only put you off steam, it can be very difficult for people who know what to expect.

my thought's

Peter

[MONAHAN STEAM MODELS]

Oops, I never claimed that this was a new idea. Just one that is not commonly used. Especially one that is not offered by any current manufacturer. I was offering up this knowledge for members here who have not heard of this method nor knew of it's advantages.

Ian, you are absolutely correct, Peter Arnot has used a similar method for years.

Bunkerbarge,

Yes I have managed to crack a method of being able to use this liquid fuel system and reliably control the burners output in real time based on boiler pressure (with an attenuator). The way that I have designed my personal system, does not use a long length of coil as I have suggested earlier since I've found that this creates a significant lag time for the burner to respond to an attenuator. I merely mentioned the coil as it is a simple yet effective way for anyone who would like to build their own system without the need of complex tools.  

As I've said the system that I designed for myself is a bit more complex (it includes a completely new burner design, a new attenuator design and a new type of fuel tank) but I don't feel comfortable divulging everything about it yet. I'm sure you can appreciate how much research and development time that I've put into this system for use in our products.

However as I have already, I willing to share the general idea of the system and how it works, as well as offer up some simple suggestions on how people can begin to experiment with their own designs. Besides that's half the fun.

[HS93 (RIP)]

I know some company's have used the twin poker idea in the past with good effect, so how about a twin ceramic burner split 50/50 and two feeds ?

peter

[steamboatmodel]

There are a number of small camping burners that can use the fuel inverted feeding liquid to the burner. They have a loop of line that runs in the flame to vaporize the fuel.
Regards,
Gerald.

[MONAHAN STEAM MODELS]

Twin poker burners would be fine and so would twin ceramic burners but in my ever so humble opinion if you have to use two burners to heat something up then my guess would be something else might be designed poorly. 

For example: the standard practice for most marine boiler makers when designing and building a larger diameter boiler is to use a heavier gauge copper tube for the main boiler shell or wrapper as this is the simplest and easiest way to gain strength. The problem is with this practice is now you have to heat up all that heavy copper before you will even begin to boil water. Not to mention you just added a huge heat sink to the mess that will efficiently radiate a lot of the heat produced by the burner away. Lets not even talk about the weight of the thing.  MHB had it right when they decided to use Nickel silver for their large horizontal boiler for the Seekadett which is almost 5 inches in diameter. They only use one small burner which was borrowed from the Cheddar puffin boilers and the boiler produces more than enough consistent steam pressure to operate a 3 cylinder engine a top speed. Plus the boiler comes up to pressure really quickly. Great design. 

One thing to keep in mind is the larger the jet that is used for a burner, the more fuel will be consumed. Also the same is true when using multiple burners. The problem with this is the faster you consume the gas the more dramatic the chilling of the fuel tank will be when firing on Butane/Propane.

While taking the opposite approach than using bigger or multiple burners and again seriously not trying to advertise or promote anything offered by myself (especially since it's not even currently offered for that matter), I've successfully designed a burner which consumes approximately half the amount of gas while producing 3 times the amount of heat and is whisper quite. I'm really not trying to be a jerk by not going into further detail but again I can't let all my dirty little product secrets out of the bag before I even get the chance to sell them. I really hope that's understandable.  A man needs to earn a living and eat after all and when that comes to a steam engine business, that's already an oxymoron. 

I'm always willing to offer up advice or help though.

[HS93 (RIP)]

MHB did use twin poker burners at one time , the idea was to use two gas tanks and yes they would have small jets so you would consume the same amount over all but from two supplies at a slower rate so less chance of chilling.


Peter

[MONAHAN STEAM MODELS]

That's interesting, I did not know MHB used poker burners in the past. Thank you for sharing that info. The twin fuel tanks make sense.

[Bunkerbarge]

Nick, If you have developed a system that controls the burner flame according to the boiler pressure while using liquid from the tank then you really have taken this to the next level and produced something very useful.  I am certainly looking forward to seeing these systems commercially available, put me down for one!

[steamboatmodel]

Malcolm Beak did an article called "In Control" in the November 1989 Model Boats Magazine. Where he describes a method of automatically controlling a gas fired model marine steam plant. I haven't built one yet, but have seen one built and operating. It worked quite well full flame when running full out and a pilot when the pressure is up.
Regards,
Gerald.

[Brooks]

A method used by US G-gauge loco steamers (and probably others too) is to keep the gas tank in a water bath. Water will soak away the cold of the tank faster than air. They will replace the bath water periodically as it gets cold.

Some engineers with also run a bubbler of steam into the bath. This slightly heats the water, so should prolong the production of sufficient gas pressure.  

As long as the gas tank is not plumb full of liquid, there should be no danger of excessive pressures with a waterbath, even with the steam heating. If the tank is plumb full, HOWEVER, there is a danger of liquid expansion which will split a tank seam....been there done that. If you are running off a commercial canister of gas, it will not be plumb full even when brand new (to protect against just this heat=> hydraulic failure mode). The danger (which exists no matter how you heat the tank) only exists for refillable tanks, and only when they are plumb full of liquid.

[kno3]

I have a question too: did anyone make a pressurized alcohol (or gasoline or whatever other liquid fuel) burner that is automatically regulated by the boiler pressure, in model size? I mean the way the gas attenuator works. I use gas firing because it allows automatic control of the fire/boiler pressure, but alcohol burners are usually simpler and if they could be automatically regulated then one can forget about freezing gas tanks.

[Bunkerbarge]

That was discussed above.  As for historically I am not aware of any system that controls a liquid fed burner from a boiler pressure signal, which is why the Monahan idea looks so useful.

[gondolier88]

Hi Bunkerbarge,

That was discussed above.  As for historically I am not aware of any system that controls a liquid fed burner from a boiler pressure signal, which is why the Monahan idea looks so useful.

For parafin fired vaporising burners a diaphragm with steam pressure one side and atmospheric pressure the other controlliung a needle valve with a 'pilot' miniumum setting- just a depth stop on the diaphragm.

There's an example in 'Model Boilers & Boilermaking'.

Greg

[Klunk]

ask a simple question..............................................!