Basic conceptual sketch of the burner from the 2 foot 0-4-0T - I'm told the development of the curve and proportioning of the rest are critical, so please don't do this at home, experts over there already have it worked out.

dave

If you have a nice clean fuel like diesel, you dont have to pre heat it and although you have to use some means like impingement to atomise the fuel you will get a fine mist. With thick heavey types of oil you will have alarge atomised ball of fuel to try and burn but it dose not fully burn due to the time it takes to reach th tube plate so you must further refine the atomising to get the small balls to aid combustion. Although fuel heating is a help the more dificault atomisationrequres more complex burners to complete the prosses. With what you discrib of fuel the steam and fuel gaps would have to match the fuel meaning an almost day to day ajustment. Aditionaly the bigger the fuel gap regardless of the fuel results in a less even flame espeshaly from a round burner and aditional eliments of the burner have to be included to keep the flame even.

I can not speak about some of the more resent FR burner work simply because I dont know whats been done. I do know that the FR/WHR is going away from oil as fast as they can so I am not conviced much development has taken place. Certainly they have not used some of the thing which I concider important in an ideal system. It is a fact that most loco work has been done from Laidlaw burners as a starting point. These have been used across the full range of fuels.

One thing I am adiment about what anyone says its a fact is that just like in Lempor chimneys the use of impingement similar to the diagram on the lempor thread is important and critical, its built in to the LD burners, ignore it at your peril.

I do not wnat to show to much of actual burners because I would rather see as a comparison what else can be designed.

Gents, Nigel was kind enough to send me some images of a Laidlaw - Drew catalog that shows their burner technology, and here they are.

I'm struck with the cultural / expepriential links between the development of the LD into the Ffestiniog / WHR burner, and with my basing the circular burner sketches on the VB. We work from what we know........ and Yank and Brit practice are very different.

It seems the LD burners were interchanged for different weights of oil, so while they are more "technological" they are also more limited individually than the VB in terms of what fuels each can handle.

dave

The Laidlaw burners come in many forms although the basic priciple is the same.The fuel comes up the middle and exits out of a gap near the top under the cap. the steam comes up the outside and is 'swirled' around the burner. Under the cap there is suposed to be the impingement and mixing for the atomising. Its dificault to extract a history but the principe point is that these burners where never origonaly intended for locos. The FR and SMR took them and after much trial and error made them work for the FR. It never did for SMR. The principle modification was to flatten the flame path by a larger flatter cap and spiral.

Over many years I have seen virsions where the spiral and caps have all been modified in many ways which would take days to list yet alone discribe so any thing you can think of has probrably been tried for this type of burner. The main problem is the spiral is milled on and thus is dificault to produce. Overal the results of these burners range from good to bad.

When I set out to do SMR in the 1990's I did look at these burners but decided to design my own using the fundimentals I had learnt. I do enficise that he whole system beyond the burner has to be looked at from the fuel through the fire pan, the burners, the atomising and the draughting. It is only when all the factors are concidered as a system can all the problems of the past be solved.

Perhaps you could share some information with us about SMR and your work there. It would help us put your last posting in context.

dave

Its very dificault to write a short discription of the SMR work but its not dificault to explain the context of it.

Firstly there had been pevious attempts to convert to oil. The first of any relivence was at the same time as the FR in 1973. The locos are bigger than FR and worked harder so had 2 inch agenst the 1.25 inch burners of FR. The fresults where far from I deal. The fuel consuption was high. The draughting was inadequate and there was masive vibration. The fuel tanks where on the roof. The boilers where not doing well. L/D not being a locomotive company never did find the solutions and after 3 years it was all abandoned.
In 1992 SMR tried again using the technology from East Aftrican railways, in your terms a wier burner. This again proved a failure as the fuel was not impinged so never atomised. the furthest the test loco got was about 200 yards up the line when they had a big blow back.
Watching this latter episode I had realised that the system was so far from anything that it had to be a radicaly better system to have any chance to work.

The burners of L/D where not instantly avalable so as I persued my developments I came up with my own design without the swirl but still using impingement. ( I can not understate the importance of the impingement of steam jets on fixed surfaces as with Lempors, and yet to this day although we know about this many people just do not apreciate how important this is) They do not need complex machining which is in the swirl of the L/D burners. I also used two burners inplace of the one to create a more like coal fired bed of heat. I reused the 1992 fuel tanks but modified to a suction feed. By now I had built many Lempors and knew of thier masive pumping power but without the masive back pressure of the traditional chimney, I modified many times the fire pan with difrent air flow paterns and areas. It was important to increse the airflow area to gain the desired combustion rate but it was only as good as the Lempor which I had to further modify for the right flow rate. The testing at first was not giving the full desired results so further investigation had to be done and superheating the atmising steam was the final part of the system. The eliments are in the firebox. The result is the reduction of vibration. Dryer combustion and reduced fuel consumption. The atomising pressure can be as low as 15psi

So its a masive difrence in the whole system to the American form of oil firing. The fuels which have been burnt in L/D burners has been many but the hevey fuels need heating, I am not tof the mind to pre vaporise the fuel as its better to keep for saftey reasons it in a liquid form till its in the burner. I have done fuel heating in some instances and its of great advantage.

As a comparison to the SMR experiance at the MW I found that basicaly the same problems ocurred with draughting and the burner they used was a small wier type under huge pressure so ejected a flame that went out of the chimney. I also found the identical papers on chimney design as at SMR which only offered solutions that further hindered the steaming capacity of the locomotives. I can not say it more definativly the the draughting is more critical to reduce the positive pressure of an oil burner and that an indication of masive vacuum is not an indication of gas flow, more a case of lack of air intake and pumping ability.

SMR was a major leason in how to get things better and worked well and has aidded further projects.

I have further investigated you coments about the guy called Dave at FR but still cant pin anything down.

He was a young man, I'd estimate in his early 20s at the time (11 years ago.)

I recall spending a happy time with him and another gray bearded guy in a greasy boiler suit who could be my Welsh twin, poor ugly bastard......hanging the rods on the Garrat during that visit. Young David broke away for a short time to take me into the shop and share his burner tinkering with me. Hope this might help you figure out who that was, and what if anything he might have to contribute to this discussion.

Ok, so you also solved drafting problems via firepan and front end engineering to make the burners useful. I'm interested in the impingement concept, and readily see how it is an integral part of the burner with the curved top. Working on another idea for adding a bit of impingement to a circular VB to also avoid the possibiolity for blowing the oil back down the tube.

dave

The nearest I could find out today was that there was someone on secondment from Rolls Royce at the time (post graduate.) This was when they did meshing to the fuel, a jet of steam next to a jet of fuel and then steam and so on. I saw a similar burner done that way in Oz which was of FR origion. I know that fuel vaporising was if tried sort lived. Certainly all the burners which are not realy standard at the moment but used are of L/D type.

In simple terms the system I used on SMR had only one component common to the 1973 L/D system was the fuel valve and even now I think I would want to alter that.

More photos from Nigel, showing Laidlaw-Drew burners in the UK including some shots of the innards, and a photo of what I think is his flat burner as built for the Grand Canyon under test. I welcome his contribution about the photos in more specifics, ar more information from anybody in the UK with Laidlaw-Drew experience.

dave

The first of the three pictures shows my test burner where I was establishing the priciples of impingement. These where taken from Lempor chimneys, Whistles and the Laidlaw burners. Its all done in a straight line, where as in the second picture you can see the spirial flutes for the steam of the L/D burner. The noticable feture on the flat burner is how the resistance to flow is greatest in the corners and also the flame starts nearer the burner. Incidentaly the flame length is proportional to the size or fuel consuption of the burner ie the more fuel the longer the flame. Its imperative that the flame length is less than the distance to the tube sheet. Idealy it should not extend beyond the fire bed like a coal burner which is why round burners ahve an advantage and better form to recreate a fire bed like coal.

The second picture shows the swirl of the L/D burner and cap. The fuel gap is not set and is between the swirl and the cap. The size of gap being depndent upon the fuel burnt. The cap shown to the left is off a F/R burner and up side down where the one to the right is a L/D cap from SMR. The forms of both the swirls and the caps are many and dependent upon the designers whim. I have even seen types where there are no swirls just a guide but I find them very undesirable to set up. There is should be another picture of one with axil flutes but yet again they do not forfil the optimum form for impingement and suction on the fuel.

The third picture shows an assembled FR burner on the left and the top of a larger burner. Both are not set up so the exit gap for the atomised fuel is not there but you will see the difrence in the cap forms.

Sketch for an impinging central burner quarter cross section. This could be very messy.........or it could, assuming proportioned right by experimentation, provide a burining cloud of gassy oil.

Nigel sent another Laidlaw Drew picture I'll try to post next. Edit: couldn't post, file too big for attachment.

dave

Good, but not a grove but flat out to the dege

Modified LD with in-line meshing fuel gap not set

I think the comparison is between the srraight steam grooves on this one and the swirling grooves in one of the photos a few postings above.

Groovy.......and both work. The straight grooves are much easier to make, however, not like hobbing a worm gear.

Anybody with a lathe, mill amd small tank engine want to make some chips and tell us how things work out?

dave

The spiral flue is more refined. The goved one gives less suction on the fuel.