Grane Mill Engine, Boiler restoration with other engines on site.
"The Steam power plant at Grane Mill is owned by the Heritage Trust for the North West on whose behalf the Grane Mill Preservation Group volunteers and associates are working to conserve and repair this unique and important heritage asset to give it the long term future it deserves."
The boilers and equipment.
The boilers fitted at Grane Mill are of the Lancashire type which is a design where there are two fires at the front ends of two furnace tubes that run the full length of the boiler shell. The hot gasses being released by the burning fuel travel along the Furnace tube to the rear of the boiler thus performing the first heating pass. The gasses are then directed by flue brickwork down the back of the boiler and along the return flue underneath the boiler thus performing a second heating pass. On reaching the front of the boiler the hot gasses are divided by flue brickwork into side flues on each side of the boiler which performs the third heating pass. At the end of the side flues the gasses pass through the side flue dampers which regulate the draft from the chimney. When the chimney is hot and creating good draught the dampers are adjusted to achieve a fourth pass through the banks of economiser tubes before the gasses are finally exhausted up the chimney.
It is interesting to note that the boiler plant at Grane struggles, especially when cold, to create natural draft from the chimney alone, so we are very dependent on the wind speed outside for draught. As a consequence an induced draught fan was fitted when the mill was running to improve the draught when required, Unfortunately this was removed when the mill closed, so a replacement will need to be fitted when the time comes.
As described above this is the front of No.1 boiler the two Furnace tubes can be seen as the two rings along the centre line of the boiler front. The fires would be at this end of the furnace tubes on fire bars with fire doors to help control the flow of air over the fire, the oval hole at the bottom is a man hole for access to the boiler shell at the bottom end.
A view inside No.1 boiler at Grane the two holes in the Furnace tubes are the Galloway cross tubes. Also the float weight that can be seen in the foreground is part of the Low water, High steam safety valve, there are normally weights hanging of the centre of the arm as well but have been removed for work to be done on them for this boiler. Also the tube on the top of the boiler barrel to the rear of the picture is the steam collector for the crown valve. The small pipe on the right of the image is the Water feed pipe from the Check feed valve on the front plate.
This photo shows No.1 boiler (L) and No.2 boiler (R). On the front of both boilers can be seen the water gauges with protectors and above them in the centre the steam pressure gauge. Above the pressure gauge on no.2 boiler can be seen the second safety valve which is the dead weight steam safety valve. The James Hodgkinson low ram stokers are still fitted to No.2 boiler and would have had hoppers fitted either side of the water gauges to feed coal in to the fires. No.1 boiler also had them fitted but they have long been removed so it is hoped to return this boiler to its original hand firing format. To the left of each boiler front can be seen the water feed pipe leading to the check feed valve.
This view shows the bottom flue on the boiler at Ellenroad as Grane's are currently inaccessible looking towards the front of the boiler.
The steam injector for feeding water into the boilers when the engine isn't running (the feed pump connected to the air pumps would feed water out of the hot well to the boiler when the engine was running)
This is a view down one of the furnace tubes at the Ellenroad Steam Museum, looking towards the front of the boiler. It is a plain type like the No.2 boiler at Grane. However, No.1 boiler at Grane has Galloway cross tubes in each separate furnace tube to increase efficiency. These are riveted water tubes passing vertically through the furnace tube to increase heating area and improve water circulation to raise more steam more quickly.
This is a view of the top of no.2 boiler at Grane the crown valve is nearest the wood wall where the steam is taken to the engine there are smaller pipes as well coming off either boiler to various processes around the mill. Behind the crown valve can be seen the Low water, High steam safety valve mentioned previously and the man hole is behind that with the wooden board over it to allow for easy inspection.
The two above views show the Green’s Economiser that heats the boiler feed-water before it enters the boiler through the check feed valves. On the top picture you can see the gears and chains that operate the scraper gear up and down the nest of 142 tubes to prevent build up of clinker. The metal covers with a pipe at the end are covering the top manifold, which is where the hot water is taken off, the cold water being fed in from the bottom.
The bottom picture shows one row of tubes looking up to the top manifold with the scraper gear visible clamped around the tubes. To give an idea where this photo is located, look at the top picture on the left side where the pipe is, the bottom picture is taken in the flue below this end of the economiser.
The fire grate of one of the Low Ram Stokers on No.2 boiler. The stokers worked by the coal entering the fire grate via a hopper and ram above the front of the fire-hole door, the coal would then drop onto the cast segments in front of the grate first where it would start burning, this would have the effect of releasing the gasses over the entire fire and help burn the volatiles off to help reduce the production of black smoke. The fire-bars that form the grate are always oscillating next to each other and in doing so move the coal to the rear of the grate where it would drop off, hopefully after all the usefulness has been released out of the fuel. The ash would then be raked out underneath the fire-grate to be removed from the boiler house by the engineer or fire beater.
The electric boiler feed pump used for the same purpose as the Steam injector. This area could have a steam Weir vertical boiler feed pump at first when the mill was built with the electric being added much later on.