The Power House contains much electrical equipment, needed for the many electrical services required throughout, the factory.
A new and complex automatic water softening plant has recently been installed, to supply the Power House and producer plant with softened water.
Wharf and Rail Traffic
Quite a number of our bottles are exported by sea; in peacetime they went to many countries but during the war, export has been restricted.
The sand as received whether Dutch, Belgian or Fontainebleau in pre-war days, or the English sands at the present time, is dried. This ensures the most accurate control of glass composition. After drying, the sand is elevated to its appropriate concrete storage silo, each of which holds about 600 tons. In other silos, we store limestone, soda ash (sodium carbonate) and cullet the name we give to broken bottles). Before elevating to the silos, the cullet is washed, sorted and crushed, to reduce its Impurities to the minimum. The batches or mixtures for U.G's. bottle glass are prepared by mixing sand , limestone and soda ash with cullet., the proportions of those major ingredients being carefully controlled to yield a glass composition of :
Sodium oxide (Na20)
Alumine (Al203) 16-15
With the aid of a travelling, weighing batch-car, which runs on a track beneath the silo, the appropriate weights of sand, limestone and soda ash, with cullet, are taken from their respective silos, and are conveyed to the mixer , the minor ingredients of arsenic, salt cake , nitre and decolouriser- being added in the case of the colourless glasses immediately before mixing.
When mixed, the batch is elevated, and by means of a second, high-levc1 batch, car, is transported to the large hopper immediately above the furnace.
The present furnaces at Charlton can be fired by producer gas or, alternatively by creosote pitch fuel. The former method of firing is cheaper and yields glasses of higher quality and better colour; in war- time, however, coal supplies have to be restricted, and at times it has been necessary to use the 1ess convenient and more expensive creosote pitch liquid fuel.
In our Chapman gas producers, the coal fuel (from Northumberland, Durham, Scottish or Yorkshire coal-fields) is converted, by partial burning in an atmosphere of steam and limited air, to the combustible carbon monoxide and hydrogen. Gaseous fuels are controlled much more easily than solid fuels. The producer gas, containing 25-27% carbon monoxide, with 12-14% hydrogen, at a temperature of approximately 600 passes along insulated flues, provided with water seals, to the gas regenerators. Rising though the gas regenerators, the producer gas is preheated by the hot brickwork to about 900 o C before reaching the furnace ports. In these ports, which are virtually large burners, the preheated gas meets air which has been preheated to about 1OOO C., and the mixture ignites to give an intense flame within the combustion space of the furnaces i.e. in the zone immediately above the batch or glass. Waste gases Leave the-furnace and pass to the chimney via regenerators which are gradually raised in temperature.
(Since September, 1946 heavy fuel oil (Pool) has replaced creosote pitch, the lower viscosity of the new liquid fuel enables circulation to be made at lower temperatures)
The furnaces hold 120-140 tons of molten glass at temperatures of 1450 to 1480 °C. With present design and with existing refractory material, the furnaces last from 15 months to 2 years between repairs and they may yield as much as 25,000 tons of glass during their useful life. These standards may be raised still further in the next few years, as furnace design improves and as better refractories become available after the war.
As structural materials we use fireclay or sillimanite (an aluminous material), or electrocast (electrically fused) blocks, to form the bottom and side walls of the refractory bath or tank (some 42" in in depth) which contains the molten glass. The furnace super-structure i.e. the portion above the glass level, is mainly built in silica materials
Intense cooling is applied to the throats of our furnaces, and also to the outside of the lower side-walls of the tank, at the flux- line 1evel corresponding with the surface of the molten glass.
(All suction machines)
The O’Neill feeder-fed machine receives the gob of glass by gravity, the correct weight bang dispensed by the feeder. The machine has rotating tables but the operation is not continuous. Bottles with internal screw finishes can be made on this machine although they cannot be produced on the Owens.
The Roirant and CSH machines deal with smaller orders that cannot be made economically on the large Owen machines these smaller machines operate on an 'in ‘and 'out' principle– they are not of the rotating type.
The method of glass bottle manufacture on the Owens machine is as follows :