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Post by Deleted on Mar 28, 2014 18:56:00 GMT
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Post by doubletop on Mar 30, 2014 8:46:12 GMT
I recognise that link :-)
My Rob Roy runs fine on gas and no mess to clean up at the end of the day
Pete
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Post by Deleted on Mar 30, 2014 12:35:16 GMT
Hello PETE-------- This link, as with most that I post on here, I came across quite by accident whilst looking for something else !!........... Glad to hear it's still running ok then..What intrigued me was that the deflector you found necessary is in reality, the same as the brick arch fitted in full-size locos and for the same reasons.......... Could you post a few notes, photos and updates on here maybe ??...........
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Post by doubletop on Mar 31, 2014 9:41:12 GMT
Yes exactly that's a brick arch. That's how it was described to me by another club members who had successfully run his Manor on gas. Actually the early photos in the sequence on the post and the video below are using his gas equipped trolley. I don't lay any claim to the idea.The point being that without it and the engine working hard combustion occurs done the tubes rather than in the firebox so the baffle keeps the combustion in the firebox. Without it the smoke box can get very hot meaning the heat isn't being transferred to the water as it should be. Much the same as full size. One thing I did come up with, well I think I did, was the tubes running through the ceramic to increase the secondary air flow. I don't think I'd seen it done anywhere before but I've now seen other burner designs using the idea. Particularly for G1 locos, the recent Derwent in ME being an example. Somebody tell me I'm wrong. There's not much point in repeating the thread over here as it provides a full story of my experiences getting the burner to work, good and bad. Later in the thread a guy from Belgium joins in and makes a similar burner for his OS Rocket. He teaches thermal dynamics at a Uni so his contribution helped a lot. So for those who are wondering what we are banging on about here are some photos   Does it work? The rest is on the thread. You'll need to register to see the photos Pete |
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Post by Deleted on Mar 31, 2014 10:03:13 GMT
Hi PETE and thanks very much for sharing that with us------Your ROB ROY is a great performer...Maybe your friend with the gas fired Manor might be persuaded to post a few notes/photos for us ??---------- I'm inspired now to have a look at my Simplex with gas firing in mind...........Just a thought on that Secondary air tubes idea}--- looking at the original positioning of the burner it appears to hav virtually filled-in the original grate space....Given that most grates have a 50% rating ( ie the width of a bar equals the width of an air gap) then your locos need for that "lost air" is quite understandable.....Looking at the gas burner in situ reminded me of the Rosebud Grate that was talked about on this forum not so long ago----- only around the other way so to speak, with gas exiting those nozzles instead of air---------
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Post by doubletop on Apr 1, 2014 9:51:40 GMT
Those three laps were part of a 20 lap (about 4.5km) no-stop marathon. You can see me refiling the tanks with a water bottle, it was a bit like a marathon at the guys were passing me water bottles as I went by.
I don't think a ceramic burner would work that well in a Simplex. As the burner fills up too much of the grate area to get the secondary air in for the correct stoichiometric ratio. To get the heat you'd need you'd need a lot of gas and then 15-16 times that of air. The Ammericans run a lot of their locos on gas and appear to use fabricated burners (see the pics at the end of the thread). Google "Marty Burners" for a design. These burners can allow a lot more air into the firebox.
The Manor has been converted back to coal (its for sale if anybody is interested). It used a tube burner much like the copper one I built and tried without success, again see the thread.
The thing with burners is getting the jet size and gas pressure right. For a particular heat you need to get a finite amount of gas into the firebox with the right air mix. Too small a jet and you need too high a pressure to get the gas into the burner and have the risk of the flame lifting as the gas velocity is too high. Too large a jet and you get too much gas and the gas/air mix goes out of bounds of the correct ratio. All a bit obvious if you think about it and the reason why a pressure gauge is a must to make sure you are running at the optimum pressure for your setup.
Pete
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Post by rickhann on Apr 3, 2014 20:21:04 GMT
Hin Pete. I have been following your posts on the Rob Roy with much interest as I want to fire my Rob Roy with Propane. I have a couple questions. Did you mount the burner level, or did you follow the slope of the firebox? Also, from your dimensions, the burner is slightly smaller than the firebox. I am assuming this gap around the burner is needed for additional combustion air. Thanks for all your work in proving that a Rob Roy can be fired with propane.
Rick
Cape Cod, MA
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Post by doubletop on Apr 6, 2014 10:53:36 GMT
Rick Its mounted level to the foundation ring. And no the gap around the edge is insufficient to supply the secondary air necessary for combustion, that's why I copied the burner and added the two extra tubes through the center. I think I explained that on the thread  I think a lot of the US guys use burners like the Marty burner found on this link. www.discoverlivesteam.com/magazine/186/index.htmI'm guessing they wouldn't have the secondary air problem. I'd like to hear from somebody who has made some of these Pete |
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Post by rickhann on Apr 6, 2014 21:03:38 GMT
Pete,
Thanks for the response. I did completely understand the reason for the additional air supply. I was just wondering if the side gaps were needed in addition to the tubes, or if it would work as well with a smaller side gaps. I did a rough calculation and found that reducing the burner box size by 1mm on all sides would reduce the burner area by about 7%. Sorry for the misunderstanding, I should have been clearer in my query. In regards to the "Marty Burner", I did consider them, but when researching them I came to the conclusion that there was not enough space in the firebox to install enough burners to generate the heat needed to fire the boiler. I am not one to reinvent the wheel, so I am going to duplicate what you have done as it seems to work very well.
Rick
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Post by doubletop on Apr 7, 2014 19:30:42 GMT
Rick
Because of the ends of the stays you can't do much about the gap. I had to dress the ends of my stays to get the burner to fit.
You can't have too much air
Pete
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Post by wdiannes on Apr 8, 2014 11:10:39 GMT
I acquired a 1.5" scale L.E. American last spring and due to a shortage of quality coal in this part of the country and with the experience in our club running propane I decided to try switching it to bottled gas. I started with "BBQ burners" but could not get enough heat so I switched to a design that other club members have been using for many year and it has been quite successful. You will find links to both on my Web site at www.diannebest.com/Projects/TheAmerican/TheAmerican.html The current burner is adequate but, if I have the time one day, I will build another iteration with about 10% more capacity. A key 'feature' of this design is that all air entering the firebox MUST come through the burner and I believe that contributes to high efficiency. |
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Post by doubletop on Apr 9, 2014 10:06:46 GMT
Dianne
I've checked your website out and you make a good point about the burner being too high in the firebox and the lower portion not getting enough heat. Its clear that a ceramic burner will have that problem given the thickness of the ceramic plaque and enough volume below for the primary air/gas mix to 'blend'. You just need to look at my two examples to see how high the burner is. Coupled with the fact that on the Rob Roy the rear axle runs just under the foundation ring. Check the other photo.
Although my loco runs I've never felt it was a good steamer however at the time I had nothing to compare it with as I'd never run loco before, let alone on coal. Now I run a coal fired Simplex I know what I should be experiencing.
As you say, getting air into the firebox and maximizing the area of burner 'holes' is the main objective. Then its getting the right jet size to feed the correct amount of gas for the heat required. Too large a jet and too much gas for the amount of air that can be effectively added to the mix and an orange flame of unburnt gass. Too small a jet and too high a pressure is required to get the necessary amount of gas which then results in the flame lifting. I find that to get the airflow correct I need the blower cracked all the time. OK its not necessary when you are running but as soon as the regulator is shut the firebox floods with gas, the Stoichiometric ratio goes out of bounds and the flame goes out. So a little blower keeps things in balance.
Pete
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Post by wdiannes on Apr 9, 2014 11:01:01 GMT
Yes, the "learning curve" is balancing the air/gas ratio as the load changes. With the box style burner, the higher the flame, the more forced draft is required, either from the blower or the exhaust. While running I keep the flame high and when slowing down I have to add more blower and less when working. Sitting idle with a low flame, just a little blower is required to maintain a positive air flow.
I lost my fire more than once getting used to the characteristics of the burner!
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Post by Deleted on Apr 9, 2014 16:32:14 GMT
Has anyone on here had experiences of driving/firing an oil burner loco ??... I was just wondering about a Diesel-fired loco ie}--- Diesel burnt as the fuel in the firebox, not a diesel-powered loco that looks like a steamer...Just for interests sake}-- A friend of mine at the SVR ( "Dave-the-Lathe" for those who might know him) had a similar air supply problem when he fully insulated his front room...It's one of those old Victorian houses that face directly onto the SVR Station at Bridgnorth....Having done a really superb job of insulating the windows, doors etc. and including a deep shag-pile carpet, he found that the new fitted gas fire went out after a few mins....The O2 sensor had cut the gas supply off...........So he lifted a few of the wooden floor boards and fitted a couple of sections of surplus boiler flue tubes running from just under the front window to just behind the burner grill = RESULT !!...Still there as far as I know...
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Apr 10, 2014 1:20:31 GMT
all the houses ive bought have had to have solid fuel fires! the best one i owned had an open grate with a pipe underneath the floor to outside feeding the grate/ashpan with air. also the ashpan was very deep and only needed emptying once a week. forget the brand name of it. current home with coal stove in the lounge is a pain as wont burn crap coal, and recent repairs to same have caused a 2 week delay in progress on STEPNEY due to cast iron parts corroding away and the lower part of the flue disintegrating! repairs to a very heavy stove and flue not recommended! very dirty and awkward job!
a late great friend of mine built a miniature loco in 3.5"g sort of copying the FR oil firing process but using on the miniature loco paraffin and steam to atomise same. it was OK and was described in ME around 1973/74. later converted to coal firing with a brick arch that i demolished whilst driving same as hadnt been told of the presence of the brick arch! personally if a loco isnt coal fired im not interested, being a coal pyromaniac from a very early age!
cheers,
julian
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Post by doubletop on Apr 10, 2014 10:09:28 GMT
Yes, the "learning curve" is balancing the air/gas ratio as the load changes. With the box style burner, the higher the flame, the more forced draft is required, either from the blower or the exhaust. While running I keep the flame high and when slowing down I have to add more blower and less when working. Sitting idle with a low flame, just a little blower is required to maintain a positive air flow. I lost my fire more than once getting used to the characteristics of the burner! Tell me about it! I do just about the same. Here's something that may help. This is my riding trolley fitted out for gas. The left hand gauge is regulated gas pressure which I have at about 45psi its also a good indicator when the bottle starts to get empty. The second gauge is the jet pressure controlled by the larger of the two knobs. I use about 5psi at the start of steaming up on the electric blower, bring it up to about 10psi until the steam pressure is about 30psi when I open the steam blower and dispense with the electric blower. Then the jet pressure can go up to about 25psi. The second smaller knob is the 'pilot' pressure control. It is in parallel with the main control so can be set to 'bleed' about 2-3psi of jet pressure even if the main jet is shut right down. That way no flame outs when the steam regulator is shut and the blower is off. You can just keep the burner on a low flame. Of course it needs a 'full off' capability and that's the red knob in the feed line before the regulated gas pressure gauge.  Despite all that nothing is infallible and if you don't get the order of things right you'll get a flame out so I generally run with a little blower going just in case of an emergency steam regulator shut off. I hope that helps somebody Pete |
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Post by Rex Hanman on Apr 14, 2014 9:46:21 GMT
Sorry to hijack this thread, but any Rob Roy owners might like to know that Andover MES will be holding another Rob Roy day on Sunday June 15th. PM me for details.  |
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Post by Deleted on Apr 14, 2014 10:55:34 GMT
---------- then they can get together and have a good "gas" about old times, 3+1/2" gauge, state of the world, etc !! (  = Cheesy grin !!) |
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Post by sncf141r on Apr 14, 2014 17:57:32 GMT
Sorry to hijack this thread, but any Rob Roy owners might like to know that Andover MES will be holding another Rob Roy day on Sunday June 15th. PM me for details. Rex; The results of this is the kind of thing I like to read about in Model Engineer - whether as an article, or a letter to the editor, or as a picture or two in the club chat column. So, if so inclined, please submit for publication! (as an aside, a few of my pictures and thoughts have made it into the club chat column in Model Engineer in the last year or so; I think there's two in the latest issue.) Thank you for organizing this - even though I can't attend for a number of reasons! (no Rob Roy, too far to fly for an afternoon, etc...) JohnS. |
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Post by Rex Hanman on Apr 14, 2014 19:18:24 GMT
JohnS, no promises but I'll see what I can do. :)Sorry you can't make it.  |
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= Cheesy grin !!)