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Obtaining Petrol from Coal

Obtaining Petrol from Coal June , 1934 AIRCRAFT ENGINEERING 171 Some Details of Production by the Low-Temperature Carbonisation Process N his speech introducing the Air Estimates in th e House of Commons on March 8, 1934, th e Right Honourable Sir Philip Sassoon, Under Secretary of State for Air, recalled that one squadron of th e Royal Air Force had been since February, 1933, operating on petrol produced from coal by the low-temperature carbonization process, and announced that it was expected that sufficient quantities of this fuel will be produced during the coming year t o provide supplies for the use of seven squadrons. I n view of this it was felt that a description of the method of producing this petrol would be of interest to readers of AIRCRAFT ENGINEERING . The following specially written account was, therefore, obtained from Low Temperature Carbonisation, Ltd., the firm responsible for the supply. The thre e principal products of th e "Coalite " carbonization process are "Coalite " smokeless domestic fuel, petrol and coal oil. number of electrodes standing at 90,000 volts strong smell and contains impurities which D.C. The electrostatic action on the gas must be removed before it is fit for use in an Th e Raw Material causes the small globules of oil to be flung to internal combustion engine. It is first pumped The coal used in th e process is washed smalls, th e sides of the chamber, from whence they throug h pipe-lines to large vertical agitators tha t is to say, a coal which would all pass drain and are led away to a collecting tank. where it is treated with some eight to twelve throug h a ⅜-in. screen and which has been In effect, therefore, the electrostatic precipi­ successive chemical reagents, each one of these washed so as to reduce the ash content to the tato r acts as a highly efficient filter which cannot being designed to remove one or more of the lowest possible figure. become clogged and which never requires impurities present and to turn the dark- Th e coal, which is brought to the plant by cleaning. coloured spirit into one which is clear and rail, usually contains from 11 to 13 per cent Th e gas next passes t o a bubbler, where it is water-white. Sulphur compounds are present of moisture, and this figure is reduced to about washed with a diluted solution of sulphuric which have to be removed, as have also unstable 5 per cent by passing the coal through a drier, acid for the removal of ammonia, which is constituents which form a gummy substance th e heat for this operation being obtained eventually recovered in the form of sulphate when the spirit is stored for any length of from the otherwise waste flue gases. The of ammonia and sold as a fertilizer. time . dried coal is elevated to storage bunkers, After leaving the acid washer the gas passes placed above each battery of retorts, each During this process of purification samples to a condenser of the water-tube type, where bunker being of sufficient capacity to hold of the spirit which is undergoing treatment an y light oil vapou r and moisture are removed. are examined by chemists in the laboratory 24 hours' supply of coal. in order to see that the impurities are being The retorts are of the vertical type and are properly removed. made in the form of castings of a special Th e Scrubber mixture and so designed as to give the most The gas is withdrawn from the carbonizing satisfactory carbonization of the charge in the plan t and passed onwards by means of ex­ Final Distillation shortest possible period. hausters. All the foregoing apparatus is on When the required stage of purification is The coal is automatically measured and th e suction side of these machines. After reached, the spirit is allowed to settle for a charged into th e retorts by means of travelling passing through the exhausters the gas goes while and is then pumped into steam-heated skips, and as the retorts are worked in pairs t o a scrubber, where it is washed for the stills, where it is fractionally distilled. A each skip holds the correct charge for two removal of petrol. The scrubber consists of a careful watch is kept on this and both the first retorts. Below each pair of retorts is arranged tall tower packed with wooden grids. The and the last part of the distillate is rejected, a cooling chamber. The cooling chamber a t its gas enters at the bottom of the tower and as it contains gaseous or other impurities lower end is fitted with a water seal to prevent passes out through a connection at the top. which would be harmful in th e finished product. th e ingress of air. Th e wash oil enters at the top of the tower Delicate apparatus is employed for controlling and cascades over th e grids in intimate contact th e temperature at which the distillation is with the gas. In so doing the oil becomes A Four-Hour Operation carried out and great care is taken to keep impregnated with petrol. The complete cycle of operations is as th e conditions uniform throughout the process. Th e stripped gas is then passed to a gas follows:— The distillate, which is constantly tested, is holder and returned to the carbonizing plant Th e retorts are discharged and recharged collected in receivers whence it flows to under­ for heating the retorts. every 4 hours, a strict time-table being adhered ground storage tanks. As each tank becomes The rich or impregnated wash oil is then to. The contents of the cooling chamber are full the contents are again examined in the treate d in a steam heated still, where it is discharged on to a conveyor, the contents of laboratory, and they are also subjected to raised to such a temperature as will distil off th e retort are then discharged into the cooling engine tests to determine the anti-knock value th e petrol without affecting the wash oil. chamber and the retort is then recharged. and the power output. If all the results are The stripped oil is then recirculated through satisfactorily up to the standard, the tanks During the process of carbonization the gas th e scrubbing plant and the crude spirit which evolved is led from the top of each retort are sealed to await release to the various air has been recovered by means of a condenser throug h an off-take pipe to the hydraulic squadrons which are flying on this type of is passed on for rectification. mains and so to the gas handling system. fuel. Should, however, the results of this final Most of the coal oil and moisture in the gas examination be below the standard which has are condensed in the hydraulic mains. The been set, then the spirit undergoes further Refining the Crude Spirit gas is then passed through an electrostatic purification and re-distillation until the proper The crude spirit is despatched in rail tank standar d is reached. precipitator for the removal of any traces cars to the refineries of Carless, Capel & of oil. Leonard in London, where it is transformed Thu s the finished product is one of great Th e Precipitator into the finished coal petrol which is sold under purit y and uniform quality, and can be relied th e name of "Carless-Coaline." When it The precipitator consists of a vertical upon to give consistently good results when cylindrical chamber in which are suspended a reaches the refinery it is dark in colour, has a i t is used in internal combustion engines. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Obtaining Petrol from Coal

Aircraft Engineering and Aerospace Technology , Volume 6 (6): 1 – Jun 1, 1934

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Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb029810
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Abstract

June , 1934 AIRCRAFT ENGINEERING 171 Some Details of Production by the Low-Temperature Carbonisation Process N his speech introducing the Air Estimates in th e House of Commons on March 8, 1934, th e Right Honourable Sir Philip Sassoon, Under Secretary of State for Air, recalled that one squadron of th e Royal Air Force had been since February, 1933, operating on petrol produced from coal by the low-temperature carbonization process, and announced that it was expected that sufficient quantities of this fuel will be produced during the coming year t o provide supplies for the use of seven squadrons. I n view of this it was felt that a description of the method of producing this petrol would be of interest to readers of AIRCRAFT ENGINEERING . The following specially written account was, therefore, obtained from Low Temperature Carbonisation, Ltd., the firm responsible for the supply. The thre e principal products of th e "Coalite " carbonization process are "Coalite " smokeless domestic fuel, petrol and coal oil. number of electrodes standing at 90,000 volts strong smell and contains impurities which D.C. The electrostatic action on the gas must be removed before it is fit for use in an Th e Raw Material causes the small globules of oil to be flung to internal combustion engine. It is first pumped The coal used in th e process is washed smalls, th e sides of the chamber, from whence they throug h pipe-lines to large vertical agitators tha t is to say, a coal which would all pass drain and are led away to a collecting tank. where it is treated with some eight to twelve throug h a ⅜-in. screen and which has been In effect, therefore, the electrostatic precipi­ successive chemical reagents, each one of these washed so as to reduce the ash content to the tato r acts as a highly efficient filter which cannot being designed to remove one or more of the lowest possible figure. become clogged and which never requires impurities present and to turn the dark- Th e coal, which is brought to the plant by cleaning. coloured spirit into one which is clear and rail, usually contains from 11 to 13 per cent Th e gas next passes t o a bubbler, where it is water-white. Sulphur compounds are present of moisture, and this figure is reduced to about washed with a diluted solution of sulphuric which have to be removed, as have also unstable 5 per cent by passing the coal through a drier, acid for the removal of ammonia, which is constituents which form a gummy substance th e heat for this operation being obtained eventually recovered in the form of sulphate when the spirit is stored for any length of from the otherwise waste flue gases. The of ammonia and sold as a fertilizer. time . dried coal is elevated to storage bunkers, After leaving the acid washer the gas passes placed above each battery of retorts, each During this process of purification samples to a condenser of the water-tube type, where bunker being of sufficient capacity to hold of the spirit which is undergoing treatment an y light oil vapou r and moisture are removed. are examined by chemists in the laboratory 24 hours' supply of coal. in order to see that the impurities are being The retorts are of the vertical type and are properly removed. made in the form of castings of a special Th e Scrubber mixture and so designed as to give the most The gas is withdrawn from the carbonizing satisfactory carbonization of the charge in the plan t and passed onwards by means of ex­ Final Distillation shortest possible period. hausters. All the foregoing apparatus is on When the required stage of purification is The coal is automatically measured and th e suction side of these machines. After reached, the spirit is allowed to settle for a charged into th e retorts by means of travelling passing through the exhausters the gas goes while and is then pumped into steam-heated skips, and as the retorts are worked in pairs t o a scrubber, where it is washed for the stills, where it is fractionally distilled. A each skip holds the correct charge for two removal of petrol. The scrubber consists of a careful watch is kept on this and both the first retorts. Below each pair of retorts is arranged tall tower packed with wooden grids. The and the last part of the distillate is rejected, a cooling chamber. The cooling chamber a t its gas enters at the bottom of the tower and as it contains gaseous or other impurities lower end is fitted with a water seal to prevent passes out through a connection at the top. which would be harmful in th e finished product. th e ingress of air. Th e wash oil enters at the top of the tower Delicate apparatus is employed for controlling and cascades over th e grids in intimate contact th e temperature at which the distillation is with the gas. In so doing the oil becomes A Four-Hour Operation carried out and great care is taken to keep impregnated with petrol. The complete cycle of operations is as th e conditions uniform throughout the process. Th e stripped gas is then passed to a gas follows:— The distillate, which is constantly tested, is holder and returned to the carbonizing plant Th e retorts are discharged and recharged collected in receivers whence it flows to under­ for heating the retorts. every 4 hours, a strict time-table being adhered ground storage tanks. As each tank becomes The rich or impregnated wash oil is then to. The contents of the cooling chamber are full the contents are again examined in the treate d in a steam heated still, where it is discharged on to a conveyor, the contents of laboratory, and they are also subjected to raised to such a temperature as will distil off th e retort are then discharged into the cooling engine tests to determine the anti-knock value th e petrol without affecting the wash oil. chamber and the retort is then recharged. and the power output. If all the results are The stripped oil is then recirculated through satisfactorily up to the standard, the tanks During the process of carbonization the gas th e scrubbing plant and the crude spirit which evolved is led from the top of each retort are sealed to await release to the various air has been recovered by means of a condenser throug h an off-take pipe to the hydraulic squadrons which are flying on this type of is passed on for rectification. mains and so to the gas handling system. fuel. Should, however, the results of this final Most of the coal oil and moisture in the gas examination be below the standard which has are condensed in the hydraulic mains. The been set, then the spirit undergoes further Refining the Crude Spirit gas is then passed through an electrostatic purification and re-distillation until the proper The crude spirit is despatched in rail tank standar d is reached. precipitator for the removal of any traces cars to the refineries of Carless, Capel & of oil. Leonard in London, where it is transformed Thu s the finished product is one of great Th e Precipitator into the finished coal petrol which is sold under purit y and uniform quality, and can be relied th e name of "Carless-Coaline." When it The precipitator consists of a vertical upon to give consistently good results when cylindrical chamber in which are suspended a reaches the refinery it is dark in colour, has a i t is used in internal combustion engines.

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Jun 1, 1934

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