Every year some two million tons of coal are discharged from colliers at Beckton Gasworks, London, and 250,000 tons are kept in reserve. The largest plant of its kind in the world handles, grades, crushes and delivers the coal to coke ovens and retorts. The plant deals also with the coke that is formed from the coal
AN ELABORATE SYSTEM of belt conveyers carries the coal at the Beckton Gasworks of the Gas Light and Coke Company from the main riverside pier, where it is discharged from colliers to the service bunker. This is a huge reinforced concrete building with a capacity of 6,000 tons. An additional bunker, of 3,000 tons capacity, is capable of being enlarged to 6,000 tons.
WITHIN ten miles of the Mansion House, London, is one of Great Britain’s most gigantic industrial plants, the Beckton Gasworks of the Gas Light and Coke Company. This plant, the largest of its kind in the world, is much more than a gasworks. It is a triumph of applied engineering, and a fine example of how the engineer deals with raw coal. The huge plant which, including the adjacent chemical works, covers 540 acres - nearly a square mile - is one of London’s most trusty servants.
Served by its own fleet of coal-carrying ships, Beckton is a self-contained port and factory where coal, the raw material, is converted into heat, light, coke and a variety of by-products ranging from motor spirit to moth balls. There are seventy miles of standard-gauge railway lines within its boundaries, a chemical works, gasholders, a new £1,000,000 battery of coke ovens, miles of conveyers and a variety of machinery. The plant is so well designed that smoke, dust and fumes are reduced to negligible proportions.
The gasworks was founded on the Essex Marshes in 1868 by Adam Beck, then governor of the company. Beck gave the place its name. The site is on the north bank of the Thames, just east of the Royal Albert Dock and is from five to eight feet below the level of the Thames at high water. Not the least remarkable of the engineering features of Beckton is that the engineers had to ensure stability for the weighty buildings by erecting them on concrete piers, built up from the ballast which lies 25 or 30 feet below the made-up ground, or on timber or concrete piles driven into the ballast. Reinforced concrete rafts laid on the marsh level support lighter structures. Engineers have overcome the difficulty of the light surface soil, and turned to advantage the transport possibilities of a waterfront of nearly half a mile for receiving coal and sending away coal, coke and other products. There are two T-shaped piers for unloading and loading ships of up to 21 feet draught and a dock where smaller vessels berth. At the main pier ships unload no less than 1¾ million tons of coal a year. A million tons of this are used at Beckton, and the remaining 750,000 tons are transhipped into barges and sent to other stations of the company.
The second pier handles coke, pitch, sulphate of ammonia and other products, which are shipped outwards from Beckton. Building material, gas-purifying material and other goods are received in the dock. A separate wharf is allocated for the unloading and the transfer of gas oil for the carburetted water gas plants at Beckton and elsewhere. The railway within the plant connects with the L.N.E.R. and a road leads to Canning Town.
SHIP-LOADING PLANT AT BECKTON. From the screening house, where all coke under 2-in is extracted, coke for export is moved on a belt conveyer. This ends in a movable belt conveyer boom which is seen slung alongside the pier. When in use this boom is hoisted to the level of the main conveyer and the coal slides down into the ship’s hold.
During the last forty years the annual coal consumption at Beckton has averaged one million tons a year. Almost all of it comes from the north country coalfields - chiefly from Co. Durham - and is carried in the seventeen ships, ranging from 1,200 to 2,800 tons, of the company’s fleet. When necessary, other ships of up to 4,500 tons are chartered.
All these ships unload at the main pier, where eight electric cranes grab the coal from their holds at the rate of 3½ tons every bite. The cranes can unload two vessels at once, at a maximum rate of 2,000 tons an hour.
The cranes disgorge the coal into movable hoppers, which deposit it on to belt conveyers, 4 feet wide, running along each arm of the pier. After having passed over continuous weighing machines, the belts meet in the centre of the pier and deliver the coal either into a hopper reserved for the loading of barges, which will take it to stations of the company above London Bridge, or on to a rubber belt conveyer 54-in wide, which carries the coal to a 6,000-tons reinforced concrete service bunker ashore. From here the coal is carried either to the storage bunkers in the retort houses or to the storage ground by the railway. The wagons weigh 5 tons each. Sixteen of them form a standard train, hauled by a steam locomotive. Trains are loaded on any of the six tracks below the service bunker by a semi-automatic charging device, which is rapid and safe.
As the demands are increasing on the service bunker, an additional bunker of 3,000 tons capacity, which can be enlarged to 6,000 tons, is being added, with a screening and loading plant which separates and grades the coal.
The new bunker can supply graded or ungraded coal to the following points: the main storage bunker, the coke ovens, railway trucks or the two adjacent retort houses. The fine coal will be separated from the run-of-mine coal and taken to the coke ovens by belt conveyers with a total length of 1,200 feet. The large coal will be reserved for carbonizing in retorts at Beckton and elsewhere.
The question arises of the storage of sufficient coal to ensure smooth working and to provide against emergencies. Beckton can store 250,000 tons, enough to keep the plant working at full capacity for about six weeks. Eighty thousand tons can be stored away under the railway viaduct which encircles the works and links the two piers, and the other 170,000 tons can be placed on the field. To reach this coal there are steam and electric navvies mounted on crawler tracks, and also crawler cranes with grabs. Each navvy can load 100 tons of coal an hour into the works wagons. The cranes, which operate in positions that the navvies cannot easily reach, deal with about 60 tons an hour.
The engineer has abolished the sweat and grime which the popular mind associates with coal. Cranes, navvies, locomotives, conveyers, a giant breaker and hammers, each created by the engineer, are the steel slaves which do the arduous work. They cart the coal from the ship, sort, clean and crush it, deliver it to the retorts and coke ovens, and charge and discharge them. The plant is operated by steel robots, controlled by skilled men.
The crushing plant which converts the raw coal into a state suited to the appetites of the retorts and ovens is in itself a masterpiece. One line of supply is a belt conveyer which brings coal from the screening plant near the pier - the gate by which the raw coal enters. Another is the railway on the overhead viaduct which delivers coal either from ships or from the stores to a line of hoppers of about 200 tons capacity below the viaduct. This coal is fed by roll feeders to a belt which brings it to the crushing plant.
DISCHARGING COAL from colliers at the main Beckton pier is done by eight electric cranes with 3½ tons grabs. Two vessels can be unloaded simultaneously at the rate of 2,000 tons an hour. The coal is loaded into movable hoppers, which deposit it on to belt conveyers 4 feet wide, running along each arm of the pier. The vessel in the foreground is the Mr. Therm a recent addition to the fleet of the Gas Light and Coke Co.
Here a revolving drum of 12 feet diameter, called a Bradford breaker, first extracts tramp iron, wood, rags and mineral matter, and odds and ends of rubbish from the coal, and then drops it on to the breaking bars and the heavy perforated steel plates of the revolving drum. This machine breaks 200 tons of coal every hour into pieces not larger than 1½-in, but this sorted and broken coal is still not good enough. It is passed on to one or other of two hammer mills, whose combined output keeps pace with the breaker. Each mill, which requires about 250 horse-power and runs at a speed of 725 revolutions a minute, reduces the coal to a size that can be passed through a screen of ⅛-in mesh.
A tramp iron separator deals with matter that the larger breaker has missed, and the hammers are adjustable to enable the coal to be reduced to a predetermined size. The coal is then conveyed to the blending plant, which consists of three blending bunkers. Below these a dozen revolving feed tables adjust the rate of delivery to an inclined belt conveyer, which takes the coal to the various bunkers for the retorts and the coke ovens.
The process of gas manufacture has been described in the chapter which begins on page 59. The gas-producing plant at Beckton consists of horizontal retort settings, coke ovens and carburetted water-gas generators. The first of these consists of fourteen retort houses, ten of which are equipped and contain no fewer than 318 regenerative settings heated by producer gas from “built-in” producers. Each setting contains ten retorts, whose capacity ranges from 11½ to 18 cwt. a charge.
On a Concrete Raft
The retorts can be discharged every eight hours, but the usual period is from ten to twelve hours. When a retort is discharged, doors are opened at either end, and a mechanical ram discharges the glowing coke into a stream of water. Then the projector shoots a fresh charge of coal into the retort. The discharged coke goes partly to the producers and partly on to a conveyer, which ultimately takes it to outside intermediate storage hoppers.
As a producer of coke the battery of sixty coke ovens, costing more than £1,000,000, officially opened in May 1932, forms a triumph of engineering. These ovens are arranged in two series of thirty ovens each on either side of the coal service bunker, which holds 3,600 tons of crashed and blended coal, or three days’ supply for the ovens. The ovens are capable of splitting up 1,200 tons of coal a day.
Before this mighty plant was erected, precautions had to be taken to ensure that the great weight could be supported. Piles 40 feet long, each designed to support 40 tons, were driven into the soil. Those piles under the coke ovens were capped by a concrete raft 2 feet thick, to distribute the weight evenly. Under each of the two longitudinal lines of the main columns of the service bunker 101 piles were driven, surmounted by a capping beam 12 feet wide and 4 feet deep. The total load on each line of columns is about 4,350 tons.
The capacity of each of these coke ovens is many times greater than that of each horizontal retort. Each deals with about sixteen tons of crushed coal, compared with the 18 cwt. of the larger retorts. An oven carbonizes about 20 tons of coal in twenty-four hours. The normal carbonizing period is nineteen hours, but this period can be varied in conformity with the demand for gas and the type of coke required. Each oven has an overall length of 41 ft 10-in, a height of 14 ft 1½-in and an average width of 17¾-in.
THE PORTAL RAM which discharges the coke ovens at Beckton Gasworks is mounted on a gantry running on rails. The ram is operated by an electric motor of 80 horse-power. The ram enters the coke oven at the back and pushes the coke out at the other end into a quenching car.
The ovens are similar in principle to those used for producing coke at a steelworks, as described on pages 168-174. The doors are self-sealing, and there are double, brick-lined gas offtakes. Chambers and heating flues are built of a high-grade silica. Heating flues are designed as hairpin flues, with waste gas circulation to avoid excessive local temperatures, so that the coal charge is
heated uniformly. Each oven has its own regenerators, arranged in pairs on either side of a central division wall.
Coal is drawn from the bunker through eighteen doors into the charging cars which travel on top of the batteries. Each oven is charged from the car through the centre of one of the three charging holes in the roof of the oven. During the charging, steam ejectors fitted to gas offtake pipes prevent smoke and dust from being emitted. Discharging occupies four minutes, charging two minutes thirty seconds. A portal ram driven by an 80 horse-power electric motor pushes the glowing coke through a travelling guide into the quenching car, which holds twelve tons. Driven by an 80 horse-power electric locomotive, this car takes the glowing mass under a quenching tower adjoining the central coal service bunker, where the quenched coke is discharged on to an inclined wharf to allow the surplus water to evaporate. Then the coke is removed through gates to a belt conveyer, leading to the central screening and grading plant.
Not many years ago coke was the Cinderella of fuels, but now that it is recognized as one of the most important sources of power it is becoming more and more important. With the increased importance of coke the grading plant has been arranged to sort and care for this fuel.
THE TIPPLER PLANT at Beckton Gasworks has a capacity of 560 tons an hour. Coke discharged from the retort houses is carried in 10-tons or 20-tons railway wagons. These wagons are grasped by the tippler and turned bodily over as shown in the lower photograph. The coke is weighed and discharged from a hopper on to a rubber belt conveyor which leads to the screening plant.
ROTARY TIPPLER IN ACTION at the Bow Common (London) Gasworks of the Gas Light and Coke Company. The loaded wagon is run on to a platform which extends from the tippler. Rails, platform and wagon are upturned by the tippler and the coal is tipped out.
The belt conveyer system carries coke from the ovens to all parts of the plant. Wagon-tipping machines (or tipplers) weigh and discharge the coke from trucks, grading and screening apparatus separates large from small coke in various sizes, and a loading machine loads it into ships at the rate of 215 tons an hour. A rail-loading machine fills large coke intended for home markets into wagons at the rate of 130 tons an hour. Clean graded coke is stored in bunkers containing nearly 3,000 tons. There are nearly three miles of conveyer belting for carrying coke.
All coke from the retorts and the ovens, except that sent direct to the storage ground, is dealt with by the grading and screening plant before it is sent away by ship, railway, barge or road. In all stages of treatment the coke from the ovens is kept separate from that from the retorts. When the plant is dealing with retort coke, the oven coke is carried to the storage ground. The plant, which can deal with 200 tons an hour, comprises a preliminary scalping machine for removing the small from the large coke, a cutting section for making the small coke, and a screening section for dividing the cut coke into the three sizes - small coke or breeze, nuts and broken coke.
Railway wagons are used to haul the coke from the retort houses to the grading plant in trains of from ten to twelve wagons, and about 630,000 tons of retort house coke are handled yearly. As the trucks arrive from the retorts the wagon tipplers tip the coke into a hopper, from which it is taken to the scalping station on conveyers. Here all coke under 2-in is removed and the large coke is sent to the ship-loading machine on the pier. The ship-loading machine has a range of movements to suit every type of vessel, and the loading boom can be lowered into the hold to avoid the risk of breaking the coke. Another screening plant at the scalping station is used with the rail-loading machine, which consists of an electrically worked boom conveyer, which can be lowered over the railway trucks. Small coke is carried to the screening section of the plant where it is screened and sent to the storage bunkers, where different compartments are allotted to each size. The bunker outlets are arranged to enable the coke to be loaded into railway trucks or on to conveyers. The grading plant and storage bunkers are in one concrete building 266 feet long, 49 feet wide and 110 feet high.
The coke ovens produce about 900 tons a day, and as the demand for this varies, a storage ground is provided near the ovens. A travelling distributor working on an elevated concrete platform distributes the coke over the stock heap of about 30,600 tons. To take the coke from this great stack a concrete tunnel has been built under the storage ground. Twenty-five outlets with valves are in the roof of the tunnel. When coke is required, a valve is opened and the coke flows on to a belt conveyer, which takes it to the junction house for grading or shipping.
A COKE HOIST AT BECKTON lifts entire trucks to the level of a conveyer and empties them there. The coke is delivered from the retort houses in trains of about ten or twelve trucks and transferred to the coke screening and grading plant.