Askern Coal and Iron Co
of Askern, near Doncaster
1930 Visit to Askern Colliery.[1]
By the courtesy of Mr. W. Llewellyn Jones, General Manager of the Askern Coal Co., and Messrs. Low Temperature Carbonisation, Ltd., the members of the North Eastern Centre visited Askern Colliery and the adjoining low temperature carbonisation Saturday, 26th October, 1929. The members were met at by Mr. H. Wilson, the assistant engineer, who then conducted the members round the surface works of the colliery.
The colliery was opened in 1911, and is situated seven miles north of Doncaster at the small town of Askern. There are two shafts: No. 1, 650 yards deep, and No. 2, 720 yards deep. From the time the pit was opened considerable trouble has been experienced, due to a number of “faults” being encountered in the coal seam, and this has restricted the output of the colliery.
An interesting feature of the boiler plant is the special type of hollow firebar in use to enable the slurry from the coal washery to be burned instead of coal. The boilers are of the Lancashire type, and the grate is formed by three long firebars, each bar being hollow. This hollow passage, about 5in. by 5in., is connected to the forced draught main, and the combustion surface of the bars is perforated by two rows of 0.5in. diameter holes spaced 1in. apart. In this way the fuel (slurry) is prevented from coking on the bars by the action of the air pressure. The slurry, as fed to the boilers, contains about 28 per cent, ash and 6 per cent, moisture. Hand firing is adopted, as this method seems to give the best results. The water consumption of the boilers is 1,100 gallons per hour. Green’s economisers are fitted, and the steam is superheated to 400°F.
The winding engines are by Yates and Thom, of Blackburn, and are 4-cylinder compound tandem engines with Corliss gear, cylinders: h.p. 36in. diameter, l.p. 60in. diameter, stroke 6ft. ; the rope drum is 24ft. diameter. The winding rope is 2.5in. diameter and has a useful life of 3 to 3.5 years, when it is renewed at a cost of about £800.
In addition to the usual reciprocating air compressors there is a Belliss and Morcom turbo-compressor utilising the exhaust steam from the winding engines. This compressor has a capacity of 20,000 cu. ft. of air per minute at 80lbs. per sq. in., and is used for supplying compressed air for working pneumatic picks, the use of which the Company is endeavouring to popularise with the men.
Electric power is supplied by two turbo-generators, one of 500 k.w. and one of 1,500 k.w. at 500 volts a.c.
The screens and coal washing plant were visited, the latter being in operation.
The members were then conducted to the entrance of The Low Temperature Carbonisation Co.’s plant, where they were met by Mr. W. R. Bell, the manager, who showed the members over the plant.
The small coal is brought in wagons from the colliery and emptied into a container in the ground, from which it is elevated by a mechanical elevator to a drying chamber, heated by the gases from the retorts, and finally distributed to the carbonising chambers. These chambers or retorts are fitted with pipes which taper from 4in. at the top to 6in. at the bottom. The coal is dropped into these pipes from hoppers arranged above; each charge is left in the pipes for about 4 hours and a temperature of 600° centigrade is maintained by gas Hames playing on the exterior of the pipes. After this time the contents of the pipes are discharged into another container and the gases conveyed to the distilling plant. The remaining fuel, "Coalite,” which contains 6 to 10 per cent, volatile matter, is released from the container after 4 hours and is delivered to a screen by means of rubber belt conveyors, and after screening it is loaded into wagons, 5 tons of ”Coalite” filling a 10-ton wagon.
The gases obtained from the process are passed along a pipe line to an electro-static precipitator, where the tar and solid matter in the gas is electrically precipitated. All the crude oil obtained is sent away to other works for the purpose of being distilled. A certain amount of benzol is extracted from the gas before it reaches a gasometer. The gas obtained is used for heating the retorts. A small gas producer plant is provided for starting up, should the works be stopped and the supply from the gasometer run out.
About 250 tons of coal are dealt with in 24 hours, of which 70 per cent, is converted into “Coalite.” From each ton of coal used, 18 gallons of tar and two gallons of benzol are extracted. At the present time “Coalite” costs 30/- per ton at the works, one ton of “Coalite” being equal in volume to two tons of coal.
At the conclusion of the visit the thanks of the members were expressed to Mr. Wilson and to Mr. Bell by Mr. G. A. Musgrave, who was supported by Mr. G. Stewart.
Thirty members and visitors took part in the visit, amongst the visitors being several members of kindred Institutions.