STEAM ENGINES AND WATERWHEELS

User avatar
PanBiker
Site Administrator
Site Administrator
Posts: 16400
Joined: 23 Jan 2012, 13:07
Location: Barnoldswick - In the West Riding of Yorkshire, always was, always will be.

Re: STEAM ENGINES AND WATERWHEELS

Post by PanBiker »

A comprehensive reply Stanley, thanks for that. :good:
Ian
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Some of what follows is from me memoir and it isn't long since I posted it but it's pertinent as part of the story I am telling at the moment.

My job as firebeater was to raise steam by burning coal in the boiler to supply all the needs of the mill keeping a constant pressure of about 140psi. The problem the firebeater continually had to solve was that the demand for steam fluctuated because it was used for process and heating as well as driving the engine. The demand from the engine could alter suddenly if the lights had to be put on because we generated our own electricity and this could increase the load on the engine by 20%. I soon learned that the secret was anticipation and the more I knew about what was happening in the mill or the weather outside the better the estimates I could make of future demand. I had to predict ahead because one of the characteristics of a Lancashire boiler is that it is slow to react, if I wanted more steam I had to act 15 minutes before the demand came on. Once I had cracked the routine and the technicalities, which didn’t take long, the job became easy and a joy because you always had to be thinking ahead. It became a matter of pride to me that steam didn’t vary by more than five pounds unless there was an entirely unforeseen circumstance.
December 1973 we had the fuel crisis and the three day week. There were power cuts and we were using oil lamps at times at the farm. We got right down to the bottom of the stock pile and I was burning coal which was sent over from the United States after the war. It was lousy stuff, I had to mix it with good coal to get it to burn! The paradox was that we were immune to power cuts as long as we had coal but it was strictly rationed. We never knew when coal was coming, we just had to take our turn. One day a wagon drew into the yard and asked if we were Bankfield Mill. I assumed temporary deafness and said yes and we backed him in and tipped his load. It was Sutton Manor Pit washed singles from over St Helens way and was wonderful steam coal. Of course I knew that he’d made a mistake, Bankfield Shed was the Rolls Royce factory and we had pinched 20 tons of their coal! It took about five days for the penny to drop but by that time it was too late to do anything about it, we had burned it. I left it to the management to sort out and carried on as best as I could. (That was the eight wheeler I posted about yesterday)
Back now to my story about firing the boiler..... I've shown you how the firebeater managed his coal during the day and I've related elsewhere about much connected with this. There was another vital ingredient that the firebeater had to control, the water level in the boiler. At first sight, this was dead easy, all you had to do was keep the water level as close as possible to midway up the sight glasses. Like everything else connected with the job it wasn't quite as easy as this. For a start off you had to be certain that the sight glasses were telling the truth. This meant that you had to make sure that there were no obstructions in the steam and water passages to the glasses. The way you did that was to blow them down at least once a day. I'm not going to describe the complicated way you used the three stop cocks on each sight glass to gain your ends all Ill say is that what you did was to arrange them so as you blew water out to atmosphere via the bottom connection first and then steam through the top one. This ensured that the passages into the boiler and through the glasses was clean. It also ensured incidentally that you were eroding the inside of the sight glass tube and weakening it and eventually one would sometimes fail. I always fitted new sight glasses at the annual inspection so this was a rare occurrence but it could happen.
If there was no protection or safety measures, a burst glass could be very dangerous. Our sight glasses were Hopkinson's and they were protected in two ways. The first line of defence was heavy glass guards around the glass so that when one burst, the flying glass splinters were caught and the initial blast of steam and superheated water couldn't fly straight out and scald the operative. The second was the clever bit, inside the passages from the boiler to the glasses, on both the steam and water connections, a large bronze ball sat in a depression in the bottom of the casting. Under normal flow conditions including blow down the ball was heavy enough to remain on its depression. But in an explosive event like a glass breaking the ball was lifted by the surge and thrown into a seating ground to the shape of the ball on the passage out of the casting and into the glass. If maintained properly once a year by making sure everything was clean, this immediately shut off the flow sufficiently for you to approach the glass and shut both the cocks in the passages connecting into the boiler. This isolated the glass and you could take the guard off, remove the broken glass and replace it with a new glass and rubber sealing rings.

Image

This is the relevant drawing from the Hopkinson catalogue no. 900 which I think was about 1920. If you want any information about boiler fittings and accessories this is the way to go! Find one and buy it.

[Here's a LINK to a copy for less than £25 on Bookfinder. Go on! You'll never regret it and they are as rare as hen's teeth!]
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Water management was important in other ways. One of the great enemies in the search for thermal efficiency is scale build up on the internal surfaces of the boiler. Ideally you want about 1/16" to strike the balance between heat transmission and protection from corrosion. In soft water districts where very little scale was formed boilers were often painted on the interior surfaces with a thin cement wash. If the railways were sending a loco out to such a district they would allocate it to a hard water district first for a few weeks to let it build a protective coating.
Our Barlick water isn't bad but scale does form when using lodge water for top up so once a day when the firebeater blew his gauges down he took a sample of clean water and brought it up to me in the engine house and I tested it for dissolved solids.

Image

Charlie Southwell, my boiler treatment man from Manchester used to call in regularly at no charge because he liked the engine. He taught me how to test and record the results and fitted me up with the equipment which I still have. The composition of our treatment was varied if necessary and after the first year we had scale well under control.
The way the treatment worked was that during the day it dissolved the scale and precipitated it out into the water. During the night when the boiler was under pressure but the water was still the precipitate settled out and because the boiler was installed correctly with a slight slope down to the front, most of it accumulated over the exit to the blow down pipe. When you came in first thing, before you started firing and disturbed the water you gave it a 20 second blow down. This kept build up of the precipitate at bay.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Feed water management had another important role. The ideal way to run a Lancashire boiler with a lag in response times due to the volume of water in the boiler was to establish a good firing rate with just the right amount of draught to achieve good combustion and a clean chimney top and leave that alone as long as possible. The feed water was at constant low level, just enough to maintain working level. If there was a variation in demand, usually because the tapes were boiling size or the shed lights had to be put in, pressure was best maintained by cutting back or even stopping the feed water input. The boiler was safe with the water as low as the bottom of the glass which was positioned to give 2" of water over the furnace tubes. In order to do this you have to have reliable and efficient feed pumps so that you can allow the level to drop in full knowledge that you can quickly return the water level to normal at will.
Unfortunately, because of lack of maintenance over the years our main feed pump, the three throw Pearn was very inefficient and even at full output couldn't keep pace with normal firing conditions, let alone catch up during operation.

Image

The Pearn three ram pump at Bancroft.

The problem was that due to the design of the pump, access to the clack valves and their seats was only possible if you completely stripped the pump and this was a major job.

The only way we could manage our job was to start the day with the water right up in the top of the glass and endure a constant loss during the day. Any variations in demand had to be managed with the adjustment of the fires, not a good way to do it. At Dinner time we gained a bit but by the time we finished at night the water was right down in the bottom nut of the gauge. I used to set the Weir steam pump on when we finished and leave it and the Pearn running while I went home and had my tea. Then I came back and stopped it when we had a full level. This didn't do coal consumption any good at all!
I've told the story before but I eventually managed to persuade the management to allow me to fit another, larger, Brown and Pickles pump.

Image

The big B&P pump in place and playing with the demand.

Once we had the new pump up and running we took the Pearn off line and did the valves and seats up which restored it to full output. We adopted a way of managing the feed which entailed running the Pearn continuously and letting the B&P pump kick in when needed. The overall flow was managed by adjusting a valve in the by-pass line. This worked brilliantly and we had no more problems. The average saving was 3 tons of coal a week, over £100. The total cost of putting the B&P pump in was £600 so it paid for itself in six weeks.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
plaques
Donor
Posts: 8094
Joined: 23 May 2013, 22:09

Re: STEAM ENGINES AND WATERWHEELS

Post by plaques »

You're going to have to run this pass me again Stanley. If the feed water pump is only there to maintain an adequate water level in the boiler, which it appears to do but requiring a lot of personal attention, Why does it save 3 tons a week on coal? There must be quite a lot of heat loss somewhere associated with this pump but I can't see it.
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Sorry If I haven't made it clear P. The saving is due to the fact that you can keep your firing rate at the best level for efficiency. That's a clear fire burning brightly and covering the whole of the bars at uniform level and ending up with a good bed of dead clinker at the back quietly falling off into the ash pit. If you have complete control of feed water levels you can manage steam production by allowing the water level to fall as more steam effervesces off as the pressure falls slightly. Ignoring the water, if you have a boiler with plenty of water in it, as pressure drops the water 'boils' and passes steam out to partially compensate for the drop in pressure. In a bad case you can stop the feed altogether.
The other advantage is that all the condensate from the mill flows back into the hot box and it is a float switch in there that controls the big B&P pump. Because it is a big efficient pump running slowly and well within its capacity it can handle water that is almost at boiling point and so with this set up, when you are injecting water into the boiler it is much hotter than anything that the Pearn could handle because it was in such bad condition. So you had two factors where you were conserving heat and maintaining efficiency, the constant settled fire and the more efficient use of the hot condensate coming back to the hot well.
There is another factor which I haven't mentioned.

Image

Here's a schematic drawing of a Green's Economiser made at Wakefield. Bancroft had one of these and the salient fact is that roughly speaking, every 10degrees Fahrenheit you raise the temperature in the economiser increases overall thermal efficiency by 1%. In a fully functioning installation the feed water is pumped through the economiser on its way to the boiler and is of course under boiler pressure plus enough differential to overcome friction in the system. With a working pressure of 140psi, this is about 180psi. The economiser can withstand this pressure and is protected by its own safety valve. the boiling point of water at 180psi is 192Cwhich is actually higher than the water in the boiler so ideal feed.
Unfortunately, the cast iron tubes in the economisers at Bancroft had, over the years been eroded and were too thin in the wall to pass the annual survey by the Boiler Surveyor so the economiser had been de-rated by removing the safety valve and replacing it with a vent pipe which ensured they operated at atmospheric pressure and this of course meant that the flow of hot gas through the economiser had to be managed to stop them boiling, a loss of about 100C in feed temperature. More if you take into account the heat losses in the pipe work and we were probably working with feed water at less than 70C.
The way we got round this was to arrange for the make up feed water to pass through the economiser on its way to the hot box where it supplemented the condensate return. Under our new system with two good pumps we used the Pearn to circulate the make up water through the economiser and could allow the return to the hot box to be at boiling point and the B&P pump could send that to the boiler at about 180psi with no problem. So, with the advantage of a well managed feed, we could send water at a constant rate under normal conditions and gain perhaps 40c in temperature. This contributed a lot to the saving.
The other saving was of course the overtime I charged for going back in after tea and then there was the fact that it took all the stress off me and particularly John, he could let his water drop away and know with certainty that one tweak of the by-pass valve in the cellar was all that was needed to start gaining again.
Let me know if I have clarified things P. It's complicated..... There are other minor factors but I have to stop going on somewhere!

Image

Here's a pic of a man who has complete control. Lovely! When John was in his chair like this we were running efficiently!
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
plaques
Donor
Posts: 8094
Joined: 23 May 2013, 22:09

Re: STEAM ENGINES AND WATERWHEELS

Post by plaques »

That makes sense Stanley, Thank you.
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Thanks P. I enjoyed explaining it to you. I'll carry on with the maintenance tomorrow. Events have rather overtaken me this morning!
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

It's always good to give yourself options. If you look at the pic of the B&P pump again.....

Image

You'll notice that there are a lot of large valves! The idea was that if necessary, even during the working day, either pump could be isolated from the system so that running repairs could be done.
When we got all the preparatory work done and Newton sent his fitters up to erect the pump Jim Fort noticed something about this particular pump and told me the story. He had chopped out the three throw crankshaft for it out of a single billet of 70 ton steel. It was a big job and it was him who told me how long it took to do it. He showed me where he had gone wrong with it. There was supposed to be a flange at each end to control the end float between the two very large bronze bushes it was mounted in but in an unguarded moment he forgot and turned it off. They rescued the situation by modifying the bush at that end to incorporate the necessary flange. That was many years ago but as soon as he started working on the pump he remembered it.

Image

We used Rochdale Electric Welding for any work we needed on the boiler at the summer break. You may wonder why we went out of the town for outside services at times. This was because in those days the Wakes Week system was universal and anyone local would have had to charge holiday overtime rates. Apart from this REW were an efficient and economic firm who could do all that was needed.
The pic above shows Dennis Sterriker, a man who started as a riveter but graduated to welding and was a superb craftsman. In this pic he is building up the swan neck steel casting that was permanently bolted to the aperture at the bottom of the front end of the boiler which was the egress point for blowing down. It carried the Hopkinson blow-down valve and was made of cast steel because it had to withstand the erosion of sediment and superheated water. Unusually it was me that initiated this repair and not the boiler inspector. The swan neck was bolted onto the boiler by four heavy steel suds and normally these were never disturbed but I was worried about wastage of the studs so we took it off and found it wasn't before time. Not only were the studs wasted but the flange faces also. Here, Dennis is building up the face of the casting with low hydrogen rods and then grinding it back to profile while has mates renewed the studs. The surveyor took note and said that he had learned something. I have an idea that several of their clients were forced to remove the swan necks for inspection and he told me later that the problems we had found were common. The insurers had a bit of a blind spot there I think.
Other common jobs were caulking or even replacing leaky rivets. In most cases you could 'caulk' them by going round the rim where it met the plate with a flat faced chisel bit in the pneumatic gun, this upset the metal of the head, sealed the rivet and gave it extra pressure on the joint.

Image

Caulking the rivets in the angle plate joint under the front of the boiler.
Fusible plugs don't last forever and I replaced them occasionally even if they were giving no trouble.

Image

This is a 2" fusible plug for a Lancashire boiler furnace tube. It was installed in the top of the tube screwed into the tube from the inside water space and if the water level was allowed to fall too low the fusible insert made of low melting point tin alloy in the centre of the plug melted and allowed water and steam to blow onto the fire, warning that there was a problem and putting the fire out. They could deteriorate over time. We had a further problem in that the screw thread in the seating for the plugs had wasted away and we were above the top size that NABIC supplied, the plugs were provided in over sizes up to 2 1/4" to accommodate worn seatings. The repair was to cut the old section out of the furnace tube and weld in a new seating bush with 2" BSP Taper threads, in effect same standard as a brand new boiler. As many of you know, I worked for REW later in my life and saw them do some wonderful repairs which other firms regarded as impossible.
Tomorrow I'll look at stoker and furnace maintenance.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

It will not surprise you to learn that the interior of the furnaces where temperatures of over 1500C were common suffered more attrition than any other part of the plant. Their design had evolved over the years and it was as good at resisting the heat as was possible. However, they were under constant attack and we had to look after them. There were two main areas, the refractories and the stokers. Let's look at the refractories first.
There were two areas of refractory surface, the half wall in the furnace tube behind the grate, the gap between the grate and this wall was the ash pit. This half wall was built with Class 1 refractories, a grade above common firebrick. It got so hot that the surface vitrified and we never had to do any maintenance on them.
The other area that needed protection was the cast iron closure of the front of the furnace tube that carried the doors and the brackets for supporting the firebars. The doors were solid cast iron 4" thick and were cooled by secondary air through the holes cast in it which was essential for the initial coking stage of combustion so they looked after themselves. The rest of the closure was vulnerable as unlike the tubes themselves, they were not backed by water and so needed protection. This was provided by a thick layer of refractory that formed two side walls and an arch over the opening. This wasn't refractory bricks but was solid refractory cast in situ using iron formers into which was rammed plastic refractory compound, it was a very stiff mix that we used straight out of the box. The brand we used was called 'Plybrico' I think. It did a good job and was very durable if properly rammed home using a wooden rammer and a heavy hammer. You didn't need any reinforcement in it and once rammed the formers could be removed. When the fires were relit the heat cured the refractory and it became a monolithic hard arch and side pieces. On average we renewed it every two years long before it started to deteriorate as In order to ram it home you had to get into the furnace and this could stop the mill for 24 hours in worst case.

Image

This pic by Daniel Meadows shows me inside the furnace doing an emergency repair on a broken hinge on the ashpit door. Luckily we managed to carry on until weekend and we blew the boiler down and gave it 24 hours to cool. Despite this It was far too hot for comfort! I could have called in outside help or sent John in but unfortunately it was my responsibility and I couldn't trust anyone else to get it repaired in time to start as usual on the Monday. Heroic maintenance!
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Image

The Proctor Unit Wide Coking Ram Stoker, to give it its full name, was a good stoker if you had plenty of load on and could maintain a full, bright fire bed in the furnace. However, like all stokers it was under severe attrition and needed to be maintained if it was to be efficient.
The action of the stoker was that a unit wide ram at the base of the hopper moved slowly backwards and forwards. On the back stroke it allowed coal to fall out of the hopper into the space in front of it and on the return stroke it pushed that charge forwards into the furnace. The speed and length of the stroke could be controlled to adjust the quantity in each charge. As the coal entered the furnace it was exposed to the heat of the furnace and started to gas off, the combustible smoke was ignited by the flame of the bright fire and was consumed in the furnace area. Large holes in the cast iron door allowed secondary air in to the fresh charge and as you can see in the picture, good coal ignited immediately and burned bright and clean. As I explained earlier, the system of moving firebars controlled by cams on the shaft across the front of the bars acted in such a way that as long as the bars were moving, they conveyed the burning bed of the fire slowly down the length of the furnace which was about 6 feet. If everything was properly adjusted, by the time the bed reached the back of the bars it was fully burned and had changed to clinker, fused ash.
The area immediately in front of the cast iron door was protected by thick cast iron coking plates which, once the fire was established became red hot and assisted in the coking process. This heat, plus the chemical and mechanical attrition of the coking process gradually eroded the coking plates and they had to be replaced when necessary. If memory serves they lasted about 18 months before needing replacement with new plates from Proctors who were still in business in Great Hammerton Street in Burnley.

Image

Proctor's foundry in Burnley. Incidentally, the worst built and maintained chimney in the town!

The next element under constant attack was the firebars. They were over 6 Feet long, about 9" deep at the widest part, tapered from the top surface to the bottom of the fish belly section and had small knobs down the sides to keep them separated from their mating bars to ensure that there was a space for the underfire draught to get through. This was essential for combustion and also to cool the bars. Without this cooling they would have burned away in no time. As it was, when the full bed of bars was exposed there were depressions in the overall surface where the top edge of the bars had been burned away.
Over time, clinker burned on to the sides of the top surfaces and eventually this needed to be ground off to maintain air flow into the firebed. To do this all the bars had to be numbered and then pulled out of the furnace. We did this every two years and again, if memory serves me right there were about 60 bars in each furnace. When they were all pulled and stacked in the empty bunker you'd wonder how they all fitted in!

Image

The firebars completely filling the furnace. Notice how the fish tail at the back end of the bars formed a partial barrier to the clinker. This encouraged it to pile up at the back of the fire and be exposed to the superheated gases for long enough to ensure complete combustion of any coal that had survived the fire. We regularly examined the ashes as they came out to check whether we were getting as near a 100% burn as possible.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

The first year after I took over I did what George had always done, I got Proctors in at the annual break to go through the firebars and the furnace. The main job, an I'll admit it was tedious was cleaning up the sides of the top surface of the bars so as to give the maximum chance for the underfire draught to get through. As I have mentioned, there were spacer pips on the sides of the bars to ensure there was a gap and when Proctor's men were doing this I realised they were grinding the tops off the pips! I stopped them and we had a bit of unpleasantness over it which ended up with me sacking them and finishing the job myself. Luckily the management saw the point, that this was shortening the life of the bars and was going to cost a lot more money. From them on I did the job myself and we never had to replace a single bar.
The small electric motors and variable drive gearboxes were relatively trouble free. We had one gearbox fail a couple of years after I took over and John had to hand fire that furnace through the very restricted doorway while Newton and I identified the trouble and got the box working again.

Image

John rebuilding the drive after Newton had fixed the broken key. I was running the engine.

The big regret at Bancroft was that I never got to swap the stokers to full under-fired which would have solved all our smoke problems. These worked by injecting coal via a screw auger into the bottom of a cast iron pot in a totally enclosed furnace. Combustion air was blown into this pot by fans and you could control coal feed and draught exactly to suits conditions. I fitted them on the boiler at Ellenroad later and they were, and are, a complete success.

Image

The under-fired stokers at Ellenroad. We won them from Oldham Hospital when it closed down and Bennis, the manufacturers, installed them for us at no charge.
Notice that on the left hand dummy boiler there are different stokers. These were also Bennis but were the obsolete shovel stokers that sprayed coal in the furnace by a spinning CI fan. Bennis had one customer in Ireland who still ran these stokers and when they needed to cast a replacement part for them they sent a fitter up, removed the part from our stokers, took it back to the works and made a replacement, then they came back and refitted our part.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

The one thing we haven't covered in detail when looking at boiler management is the draught. The furnaces need enormous amounts of air to support complete combustion. This is a complicated subject so we'd better start at the beginning. (You're right, there was a lot more to fire-beating than meets the eye!)
Newton and I were talking about townscapes one day and he said "Look at all them chimneys! And remember there was an engine at the bottom of every one of them". He was right of course, he was seeing the stacks with an engineer's eye. The question is why have a chimney. If you think it was just for getting rid of the smoke forget it. Chimneys are very clever things! The chimney ensures that there is a constant flow of air through the furnaces.
The way they do it is down to a very basic law of Physics, hot air weighs less than cold. So a flue full of hot gas is actually at a lower pressure than the surrounding atmosphere, the pressure difference depends on the height of the stack, the higher it is, the more gas it will move. Also the hotter the flue gas, the lighter the column in the stack. The chimney is connected to the back of the boiler by the flues and so once you get heat in the stack there is a pressure differential between the back of the boiler and the front of the furnaces. This means that atmospheric pressure forces air into the furnaces. Notice that this is different from the common misconception that the chimney 'sucks' air in.
When building a mill the architects had tables they could refer to which contained formulae into which you could insert the total grate area you were catering for and produced a solution that gave the height and cross section needed. The only problem with this is that these formulae all give the minimum height necessary and this is why almost every boiler was, if not short of draught, on a knife edge. I'll tell you later why I can be absolutely sure of this.
The other failure of these tables was that they didn't take into account the location of the stack or the ambient atmospheric pressure. A chimney in a valley often suffers from down draught from the hills which reduces efficiency and you would be amazed how changes in atmospheric pressure affected draught. A stack always pulls better on a sharp frosty morning with high pressure than on a muggy, rainy low pressure day. The valley problem was often alleviated by making a long underground flue up the hillside and erecting a short stack higher up, a detached chimney.

Image

Here's a good example. The stack that served the Dura Mill at Facit in the Tod Valley.

Right! Let's assume we have a serviceable stack, we need to look at how the draught is managed at the business end, the boiler. What follows is directly associated with a Lancashire boiler but similar arrangements are used for any type of boiler. The base of the chimney is always at a distance from the boiler and has to be connected by a horizontal flue. In some installations this can be a considerable length. This flue and the bottom part for the chimney itself has to be lined with firebrick, common brick can't withstand the high temperature of the gasses, often in excess of 600C even at the far end in the chimney bottom.

Image

The long flue at Ellenroad after we completely relined it. Note that at the base where is is cooler you could get away with common brick which was cheaper. Notice also the arched construction of the roof, the iron beams supporting the arches are made of cast iron, steel beams can't withstand the heat and attrition. In some flues the roof is made of thick CI plates.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Working back from the chimney bottom, the draught was managed by large cast iron doors called dampers set in the main flue. The main function of the first one was to shut off the hot flue gases from direct access to the stack and force them to divert though the economiser to heat the feed water. The temperature that the economiser ran at could be adjusted by using this main damper and also a secondary damper, the by-pass damper.
We need to shift focus now to flue gas management on the boiler itself. The boiler was set in brickwork. The hot flue gases came out of the furnace tubes into the downtake at the back of the boiler. This was divided by the mid-feather wall which kept the two streams of gas separate until they were in the sole flue that extended under the boiler to the front. The idea was that any ignition of unburnt products of combustion took place in this sole flue where the minor explosions could be contained. You could often hear this process, it sounded like a low rumbling. Some down-takes had an additional safeguard, loose cast iron lids in the top of the downtake or explosion box that could lift and relieve any pressure.
The gases are now travelling away from the chimney and towards the boiler front. At the front of the boiler two short passages allowed the gas to divide into two flows, one up each side of the boiler and head back to the main flue, these were called the side flues. At the back of the boiler the egress to the main flue was controlled by tow side flue dampers, long strips of heavy metal running in guides which could be raised or lowered by the firebeater by adjusting heavy counterweights on the wire ropes which supported the slides, pulleys carried these ropes to the front of the boiler. If you look at the Ellenroad pic of the automatic under-fired stokers you can see the counterweights at each side of the boiler. These two side flue dampers were the main control of the amount of draught on the fire and allowed the firebeater to balance the fires. In practice, with the usual shortage of draught because of lack of chimney height, on a hard pressed boiler these dampers were wide open so as to get maximum draught.
And thereby hangs a tale.......

Image

The side flue. The black object at the back is the damper.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

I said earlier that one of the advantages of being able to play with a Meccano set the size of Ellenroad was the opportunity to try out ideas and learn new things. I stated then that the formulae in all the old books were wrong in that they always gave undersized chimneys. I promised you some proof.

During the course of refurbishing the boiler and brick settings I took out all the brickwork round the boiler down to the foundations and renewed it all with Class One refractories and new seating blocks. When we rebuilt we had completely renewed the brickwork settings and flues round the boiler. I had taken the opportunity to put some of my own ideas into effect while we had it down and did things like incorporate sliding expansion joints in the side walls. Ten years later there is no sign of movement in these walls and I have never seen a boiler setting side wall that didn’t move when built in the conventional way. Another thing we did was pay particular attention to the sizing of the side flues. I made them as narrow as I possibly could and paid a lot of attention to sealing them against leakage. All this showed up when we first fired the boiler. We raised steam from cold to working pressure with only 30cwt of coal. I’ve never seen it done with less than four to five tons before. One reason for this that I worked out later was that because we had such a large chimney for a single boiler we had plenty of draught with the side flue dampers only open about four inches. Normally, with a cold boiler and flue the dampers have to be wide open to give enough draught to get a good fire going. If you think about it, the hottest, and therefore the most useful, gas is in the tops of the side flues. When the dampers are wide open this is all going to warm the flue. At Ellenroad with the dampers almost closed we were only allowing gas from the bottom of the flue to escape up the chimney, this was cold in comparison with the gas higher up and so the boiler ran more efficiently. None of the formulae in the old reference books take account of this and I really do think we discovered something significant about flueing a Lancashire boiler by these modifications at Ellenroad. That’s prime source industrial archaeology for you but unfortunately, by the time I worked it out the industry was dead!
One or two points about chimneys that might help you if you want to dig further into these wonderful structures. Seek out a book called 'Tall Chimney Construction' by Bancroft, published in 1885. I doubt if you'll find it but if you search tinternetwebthingy you'll find it as a downloadable archived file. I printed my own out and it's a goldmine of facts and figures and hard information.
I mentioned earlier that Newton said there was an engine at the bottom of every chimney. This isn't strictly true of course and if you seek out Messrs Tennant and Co's stack at St Rollox Glasgow you'll enjoy it. Tenant's were chemical manufacturers and the chimney was built to serve the boilers and at the same time carry away the horrible fumes they generated to high level so they didn't annoy the population who lived round the works. Ellenroad was a fair size at 230ft but the Tennant stack dwarfs this, it was 435.5ft ground to coping and the diameter of the shaft at ground level was 40ft.

Image

Image

Here it is in its prime and also when it was demolished. See THIS report of the eventual complete demolition, it claimed four lives.
There was another monster chimney at a Wigan chemical works which would have equalled Tennant's Stalk at least but unfortunately half way through the construction it started to lean and before they could pull it back it collapsed into the adjoining canal and blocked it.
I have to stop my discourse on chimneys, it's one of my favourite subjects. I'll leave you with two pictures to mull over.

Image

A bit of a problem......

Image

Swabs Chimney at Rhodes, Middleton. At one time the largest brick chimney in Europe.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

We've strayed a bit from the original question on daily maintenance but I think all this is pertinent and from the page views you appear to be putting up with me quite well so I'll crash on wherever it takes me.....
As we have seen, there is a lot to running a boiler economically and safely and another way to highlight good practice is to look at the bad, the mistakes that are made.
Not all the mistakes were down to the firebeater or manager. Sometimes faults occurred which were the result of long standing flaws in design or construction which took years to declare their existence. I went one day with my mate Dennis Sterriker to an emergency shout from a slaughterhouse in Carlisle who reported that their boiler was 'leaking steam' and couldn't be fired. Needless to say this had stopped production so off we went. The boiler was a small economic capabler of about 10,000lbs of steam an hour, more in fact than a normal Lancashire boiler can produce but much smaller.
When we got there they showed us where the steam had 'leaked'. There was a suspicious bulge in the insulated cladding on the front of the boiler at the top which was handy because it was easy to get to. We cut the cladding back and revealed a gap about 1/2" wide in the seam round the periphery of the front extending to about 10", the shell immediately behind it was bulged and it was obvious that this was a bit more than a leak. When we asked a few questions we learned that as was their usual practice in which they treated the boiler as just another automatic machine, the first bloke in to work had gone into the boiler house and pressed the green button before he went away to do his normal work. About half an hour later they heard a big roaring noise and found the boiler house full of steam. They had enough sense to press the red button and send for us! This was in fact a catastrophic failure of the welded seam in the shell and how it avoided zipping open the shell and developing into a full scale explosion I will never know.
Dennis cut the offending metal out and we went back to Rochdale where ha made a 'D' Patch, a replacement for the metal incorporating the corner section and replacing all the damaged area. Any of you who are used to welding will realise what a skilled job this was, welding two pieces of metal together to make an accurate curved right angled section. When Dennis had all his measurements he asked me to cut the damaged piece open so he could look at the weld. The cause was quite obvious, there was a slag inclusion in the weld and it had been hanging on by the skin of its teeth ever since the boiler was manufactured. So this was not the fault of the users, it was a manufacturing fault that should have been picked up by non-destructive inspection of the welds as part of the certification process that all new pressure vessels in the UK have to adhere to. We took the bits back and gave them to the management and left them to pursue the matter.
Dennis made his final adjustments to the 'D' Patch and tacked it in place. Then he welded it back in using multiple runs of weld using relatively thin rods, grinding out the root after every run. We got our DTI man, Dave in to test the weld and he passed it, his certificate was given to the management. Finally Dennis gave me the job of grinding and polishing the surface of the welds and when we had finished you couldn't see the join. Replace the cladding, give it a coat of paint and then do a quick hydraulic test using the feed pump to pressurise the boiler to 50% above red line. Last thing was to fire it until the safety valve lifted at red line pressure. Job done.
This was a rare fault in that it had been revealed by failure and they had been very lucky. We did point out to them that it would be a good thing if they treated the boiler a bit better by giving it more attention.
'D' Patches weren't uncommon but the need for them was usually revealed by DTI inspection when we were refurbishing secondhand boilers. Anything in the least suspect was cut out and replaced and you'd be surprised how often we found these faults.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Bodger
Senior Member
Posts: 1285
Joined: 23 Jan 2012, 12:30
Location: Ireland

Re: STEAM ENGINES AND WATERWHEELS

Post by Bodger »

When erecting a stack , how did they maintain the perpendicular in relation to the the taper of the stack ?, was a inclinometer used to maintain the stack as it rose ?
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Good question Bodge. Most chimneys were built with a 'batter' of 1" for every yard. In other words it sloped in that much. The brickies used a batter board. This was a piece of plank the a plum bob fitted and an aperture at the bottom where the weight hung. The outside edge was perpendicular but the other side which was the business end was planed with the appropriate batter on it. This was used by all the workers and ensured that en even batter was maintained.
When they built the new brick chimney at West Marton Dairy in the late 1960s the usual brickie was off ill and his replacement made the mistake of using the wrong side. It wasn't until the scaffold was removed they realised it had a dog leg in it! The outside skin had to be pulled back, cutting all the key bricks into the liner and it was built back at the correct batter without them. The only thing holding the skin in place at the top was the coping stones!
Incidentally, another rule when chimney building was to keep the mortar stiff and and never put a rise on greater than a yard a day. This ensured that the weight of the courses couldn't squeeze the joints below enough to disturb them.
There were always two types of brick, curved stretchers tailored to the diameter and altered slightly as this diminished and wedge shaped headers that had curved faces on the outside used for key bricks.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Another case study..... This starts at Ellenroad but then progresses.

It was time to fire the boiler and find out if I’d got everything right. I knew in my bones that there would be something wrong but didn’t have a clue what it would be. There was only one thing to do, run the engine in steam for the first time in 50 years. How the hell did I manage to get myself into these situations?

On the Tuesday we steamed the boiler and got about ten pounds of steam, we could set the automatic controls to hold this pressure. We cracked steam through the main and barred the engine round until the steam was passing through into the base of the cylinder. I reckoned there was enough play in the piston to allow circulation to the top so we opened the drains and left the engine warming through for 48 hours. While it was all hot and under very low pressure we nipped all the joints on the pipework and engine except for the connection between the valve chest and the cylinder. The reason for nipping all the joints is that no matter how tight you get them while they are cold you can always get another couple of turns when the metal has warmed up. I always call this following the joints up and it should be done on any piece of equipment when it has been re-built.

On this point, it never failed to amaze me how some engineers running steam plant got away with neglecting things like this. I remember once helping a firm to get a gas burner on a boiler working after it had been repaired. I found the fault and we started the boiler from cold on ‘kindle’ which is a low setting on the burner designed for slow steam raising so as not to damage the boiler by thermal shock caused by too rapid firing. The engineer said they never bothered about this and put it straight on to ‘High Flame’, the top setting. I kept quiet and stood back, awe-struck by his ignorance. At this setting the boiler started making steam after about twenty minutes and I noticed a few wisps of vapour on the top of the boiler. By the time I got up there to have a look it was a full blooded rush and you couldn’t get near it. It was steam escaping out of the top manhole on the boiler which was a mile off being tight. I told the engineer about it and he said it had always been like that since Rochdale Electric Welding had repaired the boiler. He said it would shut itself off as pressure blew the lid up against the seat! It did too, but I suggested it would be as well to tighten the holding up nuts as soon as he had a chance! There is a lesson to be learned from this; never underestimate the capacity of the human race to be stupid!
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

A couple more examples for you.....

The standard of maintenance on boilers varied from firm to firm. It was a constant source of wonder to me that a company that lived and died by the ability of their boilers to raise steam would try to save £10,000 a year by not having a full time boilerman. A lot of the problems this caused were actually down to the boiler inspector. If he was lax in his annual inspections problems could build up until they made a good job impossible, a good example of this was a boiler we went to once at a paper works on the Lancashire Moors. They had several boilers connected to one main going into the works and we were called to weld up some cracks in the tube plate of one of the boilers which was off line. I was with Dennis at the time and we decided that while he did the tube plate I would make a new valve for the feed water tank. As soon as we opened the boiler up to get Dennis in there we knew we were in trouble, it was like an oven in the combustion chamber! We soon realised that this was due to the fact that the Board of Trade Valve which was the statutory isolation valve that should have shut the boiler off from the steam main so that steam from the other boilers couldn’t leak back was faulty and passing steam. There was another isolation valve, the crown valve on the boiler. When I tried to close that it was seized solid! This is very dangerous and doesn’t happen all of a sudden, it takes years of neglect to allow a valve to get into that state. By fiddling around we got the valve working but it was still leaking. We got the temperature down enough to allow Dennis to get in the chamber to do his repair welding but I told John to tell the owners that if they wanted a hydraulic test they’d better do it themselves.
Another thing that intrigued me at this works was the fact that the large safety valve on the steam main was leaking very badly. Most safety valves will ‘feather’ a bit under pressure but this one was roaring steam out. John said that it had been like that for years because in order to repair it they would have to close the plant down. The amount of steam they were wasting meant that a twenty four hour shut down would be a very cheap option but no, they just carried on. Things like this were down to the engineer in charge and one wondered many a time about their competence.
We took a big job on up at a works at Penrith in Cumbria at one time. The plant was dedicated to converting slaughterhouse waste into ‘protein granules’ which were used in the manufacture of pet foods. All these plants used a lot of steam for the processes and we used to hate going to them because of the smell! This one wasn’t so bad because the plant had to be rebuilt after a long closure due to a fire and we were re-commissioning the boilers for them. To give you an idea of how bad the smell could get, on the night the plant caught fire the locals drove their cars up and parked them in the lane down to the plant so that the fire brigade couldn’t get down to put the fire out! By the time the police had traced the owners the plant was destroyed.
Our job was to get the two large boilers back on line. Basically it was a simple job, remove all the fittings, take them back to the shop and refurbish them all to new standard and then refit them and steam test the boilers with the inspector in attendance. One of the boilers was a bit more complicated as it had a bulge in the wall of the combustion chamber. This was a sign that the plate had overheated at some point under pressure and distorted. It wasn’t too bad so the cure for that was to jack it back into its correct position but the inspector said it would be alright as it was! John told me afterwards that this had puzzled him as well, however, once the inspector said this it wasn’t our responsibility. If it had been really bad we would have had to remove the tube and fit another one which would have been a very big job. I remember this job particularly because as I was doing one of the large eight inch, double seated safety valves in the shop a spectator who was watching over my shoulder took me to task because of the time I was taking re-cutting the valve seats. He reckoned I had done enough but I knew I hadn’t got it just right and so ignored him and did it my way. I made several trips up there to remove fittings and replace them after refurbishing them.
A couple of weeks later John sent me up to be there when the boilers were given their steam test by the inspector. The test consisted of firing the boiler from cold, watching for any leaks and rectifying them, testing the safety systems and then firing right up to maximum pressure and ensuring that the safety valve lifted at the correct pressure. This last item was in the lap of the gods because, having skimmed the valve seating surfaces, you had to set the spring pressure on the valve by guesswork. We fired the first boiler on ‘kindle’ which was the lowest flame setting and the first thing I noticed was that the flame, which should have been about six feet long, filled the whole of the furnace! God alone knew what it would be like on high flame. The boilers had been notoriously hard pressed before the fire and I pointed out to the inspector that they must have opened the burners up as high as possible to keep pressure up and this was probably what had overheated the combustion chamber and caused the bulge. He didn’t seem to be perturbed by this and it was actually none of my business so I let it go.
We carried on with the test and watched the pressure gauge carefully. You can usually expect a bit of feathering as you get close to the lifting pressure but the valve never wept at all. The inspector looked at me as we hit 150psi and said “You’ve slipped up with this one!” Just as he said it the valve snapped open and unloaded with a roar like Concord taking off. I think I must have jumped a foot in the air, he certainly did! The pressure dropped back five pounds and the valve snapped shut as suddenly as it had opened. Just at that moment the engineer came in and said, “That’s how they ought to work, sounded like a pop valve on a loco!” I told him I was pleased with the way it was working but I could do without shocks like that! I was very suited actually because that was exactly how a safety valve should function but seldom did. Another thing about it was the fact that because it was so tight, there would be no feathering and so the seat wouldn’t get eroded. It would be a good valve long after I had lost interest. We tested the other boiler, this wasn’t quite as sudden as the first but was still perfectly acceptable. The inspector asked me how I had got the valve to work so well and I told him that I had deepened the annular ring round the top of the valve slightly because it looked as though it needed it. This ring acts like an aerofoil when the valve blows and tends to lift the valve against the spring when it first opens but once the flow is established it loses its effect and the valve snaps shut. I went off down the road feeling quite pleased with myself!
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Wearing my historian's hat, all heavy repairs on boilers interested me and working as labourer or driver I saw some incredibly skilled work on problems that the layman would consider terminal. However the most interesting aspect to me was anything to do with riveted construction. This could be heavy repairs or even making an entirely new boiler. Some of the work was rectifying badly done jobs by 'experts' who had the gift of the gab and had attempted to do jobs well outside their capabilities. It got to the stage where I was looking at a loco boiler one day and knew exactly who had made the mess I was looking at.

John had a friend Hugh Winterbottom who was a driver on the trans-Pennine railway and he was a useful man when we needed something painting. He wasn’t the fastest man in the west but did a superb job. He painted Annie for us and has recently (2010) made a nice job of the Scammel Crusader after John completely refurbished it. Hugh had a Sentinel steam wagon and we made him a completely new boiler from scratch. This was to the original specification and was a very heavily made riveted high pressure boiler. Hugh had his own boiler surveyor who was a younger man and not familiar with riveted construction. On one of his visits he questioned the joint where the single sheet of boiler plate rolled to a true cylinder met. The original design was for an extra thickness of plate inside and out with two rows of rivets either side of the joint which meant there was a treble thickness on the junction of the two plates. This had always proved to be adequate, no Sentinel boiler ever failed on this point of design but the young surveyor was worried about it and wanted John to ‘reinforce’ the joint by welding the strengthening plates down the edges. John had to work very hard on him to educate him and show him he was wrong. If we had done what he wanted we would have destroyed the joints capacity to flex and this would have weakened the construction. As the old surveyors died out and experience of riveting was lost this became more and more of a problem. Very hard to understand considering that the oldest boilers working safely in the country were all riveted.
Lack of knowledge and experience wasn’t confined to the surveyors. Some firms of boiler repairers were less than adequate. We had a good example in the shop once. A local man who wanted a traction engine found one for sale at a suspiciously low price. When he enquired he found that the reason for the low price was that the backhead of the firebox had been condemned by the owner’s insurance surveyor because of ‘grooving’ in the sharp bend of the back plate down each side of the box. This is quite a common fault and is a combination of corrosion and internal stress in the metal on the sharp curve during cycles of expansion and contraction stemming from stress induced in the metal during the forging of the bend during original manufacture. The man who owned it consulted various ‘skilled’ practitioners and they all said it needed a new backplate, a major and very expensive repair.
The bloke who was considering buying it asked us to have a look at it and John told him we could put it right at a much lower cost. The man bought the engine, a lovely little thing with a roof, rubber tyres, brakes and a winch built into one of the driving wheels, everything that Annie lacked! So, the question is how did John manage it?
Remember that the original problem was a flaw down each side of the backplate in a very inaccessible place because it was shielded by the horn plates which run down each side of the footplate and support the gearing. John reasoned that all that needed to be done was to cut out the affected metal and weld in new metal to cure the weakness. To get at this we would remove the wheels and gearing and cut adequate access holes in the horn plates which could be patched afterwards. None of this is easy but it is possible. The man bought the engine and brought it down to the shop.
The first job was to get the wheels and gearing off to get access to the horn plates. John gave me the job and using the crane I lifted the back of the engine and blocked it up securely with very large timbers. Once the back wheels were off the ground it was just a matter of careful dismantling until the welders had a clear way in, I think I had it ready in less than a day.
Paul moved in and cut a large access hole in each horn plate leaving enough metal top and bottom to maintain sufficient strength to hold the footplate together. He made as clean a cut as possible and once the plates were out they were ground to a ‘V’ shape around the edge ready for welding back in. With the back plate accessible Dave Jones our non destructive test (NDT) man came in and mapped the areas of weakness for us using ultrasonic testing. Paul and Dave agreed how far to extend the repair beyond the obvious flaws so as to make sure any potential areas of future weakness were cut out. Then Paul did what to a casual observer would look like vandalism. He cut out all the weak and affected metal and finished up with two long slots in what was then a totally useless backplate.

Image

You can see here how the outer plate has been cut away to get to the flaw in the backhead. It’s been cut out, welded back up and the white paint you can see is the developer for a dye penetration test which seeks out any flaws in the weld.

This is where the welder has a different view of the world, he doesn’t see a catastrophic flaw, he sees a hole that needs cleaning up and filling with good metal. This is the good welder’s skill, he can lay down runs of molten metal down onto the parent plate and gradually fill the hole until he has a complete closure with a slightly raised surface. This is ground back and polished until the only way to identify the area of repair is by the polish. Dave Jones came back in and under the boiler surveyor’s watchful eye tested the repair and certified it.
No need to do anything about the polished metal, it would soon pick up a patina of dirt and oil baked on by the heat when the boiler is firing. Paul welded the sections back in the horn plate and polished the welds flat. A couple of coats of paint and it’s time for Stanley to move in again, rebuild the gearing and fit the driving wheels. While I was doing this Paul re-tubed the boiler. In short time the engine was back together, lifted off the blocks, hydraulically tested and ready to go forth into the world for its steaming test. The nice thing is that not only has a serious fault been cured but the backplate is in better condition than when it was new because all the internal stresses have been taken out of it. The man who bought it had a very reasonably priced engine because he had gone to the right firm and tapped into the expertise that existed inside REW. Can you wonder why I enjoyed watching skills like this being used?
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

The other great asset I had at Bancroft was the knowledge that half a mile down the road I had Brown and Pickles who could take on any repair job, no matter how big. If you haven't read it, go back in this topic and have a look at my account of the firm. By the time I was dealing with them they only had a few engines on the books and I knew that one call to them would get an immediate response. When Mt Birtles asked me to repair the broken spring on his car because the local garages couldn't give him a fast solution I told him that we were lucky in that you could get attention for the engine faster than a response from a garage for a minor repair. In addition, I don't think Newton charged for his visits, he saw it as a nice diversion from the day to day work they had in hand.
The only place I ever saw such good service was that of REW when they got an emergency call. I may be wrong but I think that this sort of service is thin on the ground these days..... Unless of course it is a call to an accountants to come in and supervise an administration or liquidation where enormous fees are assured. Perhaps I am just a cynic.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

On the wider front, running the engine at Bancroft was probably the best job I ever had. Don't get me wrong, I always enjoyed my work, I must have been lucky, but running the engine ticked all the boxes for me. I never lost interest in the actual mechanics of the job and kept up with my reading. Sarco, the firm who made steam traps and accessories ran a correspondence course on steam, it was free and I did it as I sat at the desk in the engine house and completed it. They didn't grade you but it was very instructive and I learned a lot which I put into practice and I have no doubt my time was well spent in terms of the benefit to the management. I remember our managing director Mr Birtles noticing the papers on the desk one day and I think he was a bit surprised when he learned what they were. I think he automatically assumed I was up to mischief. I think it had an effect because I was never refused any of the orders I put in for Sarco products!
The biggest change for me was being freed from the solitary confinement of the wagon cab. No cell phones and the only contact you had with the rest of the world was when you got out of the cab. I didn't see that as a disadvantage while I was doing it but when I started at Bancroft and was meeting lovely people every day I realised what I had been missing. That was the big bonus and because I was working hard to do a good job people recognised this and soon decided I was OK. Part of this was the change from George Bleasdale, the man I replaced. He was not liked and made no attempt to do anything about it.
Like the wagon, I had complete autonomy. Nobody in the mill apart from John Plummer had any idea what engine tenting entailed and so as long as the shaft was turning the management left me alone. I once had a conversation with Sidney Nutter in the office, he had worked at Bancroft all his life and he told me he had never seen the plant run as well or as economically. He said it was obvious that I was doing my best and always chasing better efficiency. Apart from Jim Pollard the weaving manager and Newton he was the only one who lst me know he was on side.
The weavers had the best view of what I was doing, all they had to do was look at how the looms were weaving and their wage packets. The consequence was lovely relations with the shed and it made all the difference. I still look back on them with affection, they were the best people you could have to work with.

As you can see, I am running out of steam a bit. Ask me questions please if there is anything you want me to cover again. I shall do my best to keep you reading but it would help if you pressed me!
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
User avatar
chinatyke
Donor
Posts: 3831
Joined: 21 Apr 2012, 13:14
Location: Pingguo, Guangxi, China

Re: STEAM ENGINES AND WATERWHEELS

Post by chinatyke »

Re: Your post of 6th September and side flues.

Did the flue gases always go around the outside of the boiler like this? Something I didn't know. I can see there would be a heat advantage on the boiler shell but I would have thought the flue gases would be very dirty and at too high a temperature. Anyway, isn't that what the economisers did?

My only experience of steam raising is a couple of small self-contained upright multi-tube boilers, very simple and only about 1000 lbs per hour at 100 psig, and a CHP (combined heating and power plant) where the exhaust from a gas turbine was used to raise steam in a boiler, I think it was 28 tonnes per hour at 12 barg, about 190C.
User avatar
Stanley
Global Moderator
Global Moderator
Posts: 89914
Joined: 23 Jan 2012, 12:01
Location: Barnoldswick. Nearer to Heaven than Gloria.

Re: STEAM ENGINES AND WATERWHEELS

Post by Stanley »

Good question China. The first thing to say is that the products of combustion in a conventional furnace burning some form of fossil or carbon based fuel are never too hot to be used, being 'dirty' has no effect on heat transmission. This means that in all steam raising plant, no matter what type, a common goal is to have the maximum heat raising area exposed to the high temperature gases. In modern tubed boilers this is achieved by having multiple passes of tubes, up to five are commonly used. In the case of shell boilers like the Lancashire or Cornish single flued type this was achieved by exposing all surfaces below water level to the hot gas and this is why the common practice was internal furnace tubes discharging onto a downtake which exposed the back of the boiler, from there into a sole flue under the boiler and then divided in two to pass down each side of the exterior before being discharged at the back to the chimney. Diverting these gases through the economiser enabled even more thermal efficiency to be achieved by heating the feedwater to the temperature of the superheated water already in the shell. In practice the number of tubes in the economiser was designed to get the discharge from it to the chimney to a temperature of approximately 600F as this was needed to excite the chimney gas column enough to generate sufficient draught to keep the system going. This was seen as essential because most plants had undersized chimneys as I have said earlier. The heat in the flue gases emerging from the chimney top is, in terms of thermal efficiency, pure waste but as I say essential for getting enough draught to keep the flow going.
In some systems, noticeably in oil fired ships with relatively short funnels, a 'forced draught' system was used where the boiler room was pressurised by fans to well above atmospheric pressure to force air into the combustion zone. In some modern economic boiler installations with short chimneys 'induced draught' was used generated by a fan at the base of the chimney forcing the gases to atmosphere which generated enough draught in the furnaces. These of course operated at high temperatures and were a source of trouble needing high levels of maintenance. In the case of steam locomotives the draught is achieved by discharging the exhaust steam from the cylinders up the short chimney via a 'blast pipe', inducing a draught that increases in strength automatically with greater demand.
If you want to read the bible on this seek out two books, both issued by the then Ministry of Power: 'The efficient use of fuel' published in 1958 and 'The Efficient use of steam' published in 1947. I have copies of them and both came from the library of Reuben Burton who was a manufacturer in Nelson.
So, to go back to your question, "Did the flue gases always go around the outside of the boiler like this?" The answer is in most cases yes. The reason why it was done and the way they arrived at these solutions can be found in the early history of boilers. The early boilers were nothing more than a large copy of the domestic kettle sat on a trivet. Then it was found that if the gases were conducted round the outside of the boiler in a circular flue this increased efficiency. From there the practice became to expose the whole of the exterior of the boiler, whatever the type to the hot gases. The first use of an internal tube in a boiler that I know of is in a boiler made of close fitting granite slabs with an internal cast iron flue that was used in Cornwall to extract heat from the exhaust gases from a smelter. There is little doubt that Trevithick knew about this and at the time he was heavily involved in the Cornish mining industry which was heavily influenced by a monthly publication called McLean's Reporter which conducted independent tests on mine engines and expressed the results in amount of water raised against bushels of coal used and every engineer and mine owner wanted to improve this 'duty'. This stimulated many improvements in engines and boilers and there was a rapid advance. Trevithick contributed to engines but his major achievement was to design what became known as the Cornish Boiler, an all metal (wrought iron at first) riveted shell with a single internal furnace tube and a flue system very similar to the one I have described.
At that time the biggest steam users in the country were the textile manufacturers of Lancashire and they rapidly adopted the Cornish boiler for steam raising in mills. Then there was a major innovation, the product of general experience but owing its perfection to Sir Henry Fairbairn, the Lancashire boiler which was larger and had two furnace tubes. This increased the heating service and improved water circulation past the tubes but it's worth noting that the twin flue approach was driven mainly by the fact that it allowed the two furnaces to be hand-fired independently and managed so that when the volatiles from the newly fired tube met the incandescent gases from the other, the smoke was consumed giving better thermal efficiency. The adoption of the twin flued boiler led to refinements in the flues like ideal sizing and the introduction of the mid feather in the downtake to stop damaging explosions there and confine them to the sole flue. There was also an innovation introduced by the firm of Galloways which was to introduce a small water tube in the rear of each furnace tube to increase heating area slightly but that never caught on. The last attempt at innovation was the Yorkshire boiler that introduce a third furnace tube but this caused so many problems in use and was also more expensive to manufacture that it died the death.
By the time all these innovations were made, the Lancashire boiler had reached the peak of its efficiency, reckoned to be about 75% thermal efficiency in a good, well managed installation running at 75% of steam raising capacity. The only changes that came later in the 20th century were one piece corrugated furnace tubes, 'German' or dished ends to do away with strengthening gussets in a normal flat fronted boiler and all welded construction. I have seen modern Lancashires built like this rated at 300psi but not many were built. The last ones I saw were in the Lucas factory at Manchester but they had been bought cheaply when new from John Thompson in Glasgow as there was no market for them and ran all their lives at 40psi for the heating system.
The Lancashire boiler died because it couldn't match the thermal efficiency of the modern tubed economics but in terms of ease and cheapness of maintenance and longevity they were never bettered, many are still in service still rated at their original pressure over 100 years after they were made.
One last observation. The Lancashire boilers that have survived are all from mills where they were used to power steam engines. This is because it was a characteristic of this use that constant steam pressure was kept at all times. Boilers used in the brewing or dying industries which suffered violent swings in demand gave more trouble as their shells were flexing all the time. Riveted boilers can cope with a small amount of this but not constant repetition.
Stanley Challenger Graham
Stanley's View
scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!
Post Reply

Return to “Local History Topics”