I have been thinking about a vaporizing waste oil burner for many years Matt; what i haven't been able to overcome is the variability of the waste oil and the noncombustable adulterations that come along for the ride and gum up the works. The best of the burners made by Nigel and Boston Lodge, etc, do a fine job of vaporizing and providing for efficient combustion but are tuned for a clean supply of light relibale grades of fuel. I'm considering now tinkering with a centrally mounted circular atomizing burner instead, located in a firepan / drafting box like Nigel's with a lot of smallish pipes imparting a swirling effect to the draft. What I'm not clear on is the potential for adding secondary air towards the top of the firebox - much like GPCS does for coal - in an effort to provide for better more complete combustion of the droplets that get away and head for the tubes. Haven't found anything other than frequent cleaning to deal with the junk in the oil issue.

Of course, I don't have a locomotive to try things out on now, being out of the business apart from armchair stuff. Anybody else working on these things wants to brainstorm and tinker, preferably with access to a rolling steam powered laboratory?

dave

Mr Austin here are a few points you have over looked.

Firstly, the paper is about why Lempors should be used with oil firing, NOT oil firing. I have worked on other papers on other aspects of oil firing which are not the topic here. The concepts are all valid due to the fact they are all tried proven phisicaly. I am a man who is intrested in the the practical chalenges of actualy making things work rather than words.

1 Steam atomisation reduces overal eficentcy? May be so but it is to find a way of limiting any losses which is important. One is using atomising steam which is hot enough to vaporise the fuel hence superheated steam for burners. The savings are around 10% of the fuel compered to saturated atomising steam.

There is a significant difrence in liqiuid fuel firing like oil to that of solid fuels and the presence of water or steam. I refer to the use of coal in the production of gas (town gas) where water is used on coal to produce water gas which is then burnt in a secondry combustion. I do not wish to dwell on it here but it is known as the Gas Producer Combusion System (GPCS) and can be found on both Hugh and Martyn's sites. So a comparison between the steam of a coal stoker is not relivent.

Oil is at totaly difrent situation. The ultimate 'ureka' moment I had with respect to oil and exsesive water in the fire box was when I watched an advert for the safty of cooking oil fires where you do NOT use water to put the fire out. If you doupt me then go to your fire house and see what the fireman has to say on the subject. Super heated steam has been used since the early part of the 20th century for oil firing so its tried and tested.

2 I have seen burners use up to full boiler pressure in an atempt to get atomisation. With the pressure so high the flames came out of the firepan in serch of oxygen to burn. The blower was full on to try and keep a control on the situation. This was only standing still and so when moving the front end was even less able to keep a control on the situation! I thought the gasses where supposed to pumped through the boiler by the front end?

How can this be reduced as the firebox size increses? If anything the flame length has to be longer and needs more pressure to achive a longer flame simply to fill it!

You quote figures of vacuum and back pressure. This dose not prove eficentcy for combustion as its easy to achive high vacuums (over 20 inches)when pulling at a small inlet for the air which is quite common situation for low eficentcy front ends as they can not achive the high gas flow rates for higher combustion and steaming rates. Efcentcy of the front ends is mostly concerned with the pumping of exhaust gasses and so you have to balance the vacuum agenst the combustion gas flow rate for a given back pressure which represents the desired steaming rate.
So the high vacuum figures you give represent the void and lack of air inlet area which allows in the air for combustion. So what you are saying is these locos you list do not have enough air coming in for combustion. (Somthing we had to correct at both GCR and WCWR) So what you are discribing is a low combustion rate for a large boiler at low eficentcy all because of a low front end limit because of its design.
That brings us back to the fundimental point of the type of front end used to get the best out of a locomotive must be the most eficent and at this point in history its a lempor.

3 You may be not sure but I can confirm ( by practical experiance) with out doupt that super heating is most important.
Beyond the efects in the firebox there are three ways to atomise fuel,
a)pressurisation and spraying through orifices,
b)impingement
c)vaporisation
Most steam burners on locos use b and c although imingement is confined to some rotory burners.
With out doupt the heat of super heated steam aids c and yes you are right fuel heating is important and under used.

Your coment about a 'fire box not knowing or caring what is sucking the gasses through and dependent upon the firebox' is not acurate. The front end matters to an extent beyond anything else afecting every part of the locomotive. What happens there afects everything including the rate and quality of combustion in the fire box So the firebox cares about the sucking device.

Many people have worked on draughting for many millions of hours to improve this aspect of the locomotive. I never set out to be an expert in front ends but it is with out doupt the most critcal item on a locomotive. Its the only one you can alter and improve in a short period of time and make a masive difrence to the locomotive. 'It's the control system of the whole locomotive.' Get that wrong and you condem the rest of what could be the best loco in the world. This goes for what ever the fuel is from wood, waste cane, coal or oil it dose not matter, the front end is most critical part, period and the best avalible is a lempor, if it was not then I would be building what ever else was best. I dont know how more clearly to say it in words. The hardware I have done says it best.

If you wish 'To a steam locomotive a Lempor is like a turbo charger is to a diesel engine'

What you say about the consepts of the actual cobustion system in the lower section of the firebox is valid and good air fuel mixing is critical. Primary air is more important to an oil burner than coal but again with what ever fuel the need for a good pump for the combustion gasses is the number one priority. Your discription of extra large air ducts is correct and multiple small ones are the preference. As is also the need to limit the surplus air which absorbs usful heat which can not be extracted.

So I can't see where some of your conclusions come from? How do you explain why I have been able to make sizable gains by simply converting from a traditional front end to a Lempor with either coal or oil as listed in my paper?

NOT the marine circular burner, Matt. I'm imagining taking a standard flame thrower, and twisting it around in a circle until the ends of the slots meet each other, and maybe with some little modifications to possibly decrease droplet size, and certainly with features to make for easy removal, disassembly, cleaning and reinstallation. On the little teakettles I have done most of my work on, we have no room to make for a long throw before impinging on the flash wall.

dave

Facts:- Some taken from books, the rest is from my work which is not published so is new here. Belive them or not I don't mind.

The Great Eastern Rly used and documented the super heaters on thier Jazz trains in and out of London in early part of 20th centry saved 10% of fuel

The work I have done confirms this fact 150%

Drumming may be a name for it, What ever. The exclusion of the fire is due to the super heating of the very wet atomizing steam to explosive proportions as discribed like a cooking oil fire having water put on it. Super heating atomising steam reduces this problem concidrably.

The burner you show is not suitable for loco work. What Dave says is correct and can be used to form an artificial fire bed similar to a coal burner. Air must go in as close to the burner as posible. A good air intate area which is used with a Lempor and radial burners is about 80% of the GFA of the tubes.

You show the draughting data graph of the Layden. It took me a while to realise just what it said. My interpritation was that the vacuum is decreasing as the back pressure incresses! Thus the desire for more evaporation and combustion gasflow due to the incresed work load is not meet. I have then plotted that data crudly over a recent oil fired (because 3751 was oil fired) graph of one of my Lempors and find that the front tube plate draught is well 'on another planet' as it starts at the common Zero and goes of the top of you graph at around 2psi back pressure heading for 10 inches of vacuum at 10 psi compered to less than 1,5 inches for the Layden!(Maybe the graph will get posted later here) Even my blowers are desighned to give 2 inches of vacuum at 85% of boiler pressure.
So do you still maintain that a Layden is a good draughting device? So will you now admit that such a powerful tool such as a lempor can have a dramatic efect upon the combustion gas flow mass on the firebox and combustion with in the firebox thus disproving your origonal statement? By the way the savings on the improved air/ fuel mixing resulting in the firebox from the lempor of the locomotive above was over 20%. The rest of the capabilities of a lempor will be shown on the Fowler.

Here's an upload from Nigel Day. I'll leave the commentary for him:

Thank you Tim for posting the graph for me, I know its a bit rough in presentation but shows the coments I made above. As far as I am concerned I have made my point and I have other things like Dennis's lempor to do.

My interpretation of the graph that Matt posted (and the Y axis label is confusing in this regard) is that it is showing inches of draft PER pound of back pressure; see the mid-chart labels for each group of curves. So to get actual inches of draft you need to multiply. This would wind up looking something like the red line below for the data from the solid line in the middle group (draft in firebox) on Matt's posted chart:

Certainly it shouldn't be LESS draft for more back pressure as indicated on the second chart posted.

I was scratching my head about that.......if the captions are correct, it is charting draft against back pressure, not draft per pound against either draft or back pressure. The lines in Matt's chart are labeled "draft per pound" even though that's not what the axes is captioned.........which may explain why, at first glance, it doesn't seem to make intuitive sense while the red and blue lines on Nigel's chart does. So, if I want to divide, which axis on Matt's chart is the constant?

dave

This made me wonder if in fact the lines on Matt's charts are actually the derivative (rate of change) of draft. That would make a little bit more sense, as then the graph tells you exactly what draft improvement you'd be getting for each pound of back pressure. That would make the actual draft be the integral (or area under the curve) of the data. This is shown as the yellow line below. (Computed with Riemann sums, so it's not the most accurate calculation in the world; on the other hand I eyeballed the input data anyway. :)

Thanks for that. Looks like my first interpretation (and the red line on my charts) was correct.

Have not set up my computer for download of mental fabrications yet, Matt......just working on it as theory. Here's a bit of a description of two things I'm mulling over, both concentrically cored cylindrical castings vertically mounted in the center of the firepan:

1. Concentrically cored casting with steam coming up the inner central hole, oil rising up the outer cylindrical core. The casting is topped with a sort of lid and the outer ring of the casting is topped by a shelf perhaps an eighth or so below the lid. A bunch of tiny holes are drilled through the inner ring of the casting, allowing many tiny jets of steam to blow the oil off the shelf outward in all directions.

2. Oil rises up the middle hole, steam comes up the outer cored ring. The steam core is topped by a slot all the way around of about .035 or so.......so it blows out in all directions through the narrow slot. The oil rises up the central core and "drools" out over the top and down in front of the slot and gets caught up by the circular steam jet and is blown out in all directions.

Think of both as steam atomizing sprinkler heads for dirty waste oils of very broadly varying consistencies. I expect the oil would be very well warmed by the steam in the adjacent cavity, and I would certainly borrow Nigel's great idea of a superheating coil for the atomizing steam in the firebox, and for little tubes for directed draft through the firepan. In both cases, we'd need to be able to easily disassemble, clean, and reassemble the burners as they get clogged by grunge, and the mounting should provide for fast exchange between burners.

Maybe I'll tinker with some metal a bit and see if I can get somebody with a little tank engine to try it out.

Thanks as always for some very intersting information, and for the explaination about the graph.

dave