products which are wasted in the beehive oven, yet statistics show that less than 607o of coke manufactured today is produced in the by- product coke ovens.
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NATIONAL ASSOCIATION of COST ACCOUNTANTS Affiliated with The Canadian Society of Cost Accountants it Official Publications Vol. IV DEC. 1, 1922 No. 6 Cost Practices and Prob- lems In the Production of Coke BUSH TERMINAL BUILDING 190 WEST 42nd STREET, NEW YORK
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NATIONAL ASSOCIATION OF COST ACCOUNTANTS Affiliated with The Canadian Society of Cost Accountants Official Publications Vol. IV, No. 6 December 1, 1922 Cost Practices and Problems in the Production of Coke C. C. SHEPPARD, Sheppard and Co., Pittsburgh, Pa. BUSH TERMINAL BUILDING 130 WEST 42nd STREET, NEW YORK CITY
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The National Association of Cost Account- ants does not stand sponsor for views expressed by the writers of articles issued as Publications. The object of the Official Publications of the Association is to place before the members ideas which it is hoped may prove interesting and suggestive. The articles will cover a wide range of sub- jects and present many different viewpoints. It is not intended that they shall reflect the particular ideas of any individual or group. Constructive comments on any of the Pub- lications will be welcome. Additional copies of this Publication may be obtained from the office of the Secretary. The price to members is twenty -five cents per copy and to non – members seventy -five cents per copy. x! COPYRIGHTED BY NATIONAL ASSOCIATION OF COST ACCOUNTANTS DECEMBER 1, 1922
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National Association of Cost Accountants COST PRACTICES AND PROBLEMS IN THE PRODUCTION OF COKE Note: This paper is one of aseries presented before the Pittsburgh Chapter. These papers dealt with cost accounting in the iron and steel Industry from the ore to the finished product. It is the intention of the Publications Department to publish some more of these papers as Official Publications. The term coking is used to denote the process of preparing, from bituminous or other coal, a fuel adapted for metallurgical and other special uses. The operation consists of expelling by heat the gaseous elements from coking coals, leaving the fixed and de- posited carbon, ash, and the residue of sulphur and phophorus. These elements constitute what is known as coke. Three methods have been, or are being used, in the manufac- ture of coke. These methods may be referred to briefly in the following terms: 1, Coking the coal in heaps or mounds, in the open air; 2, coking the coal in the beehive or round oven partly enclosed, with the air partially excluded; and 3, coking in retort or closed ovens, with air almost entirely excluded. The first method has almost entirely disappeared owing to its obvious wastefulness, as well as the evident difficulty in operation and limited production. The second method is still prevalent in most of our coking fields on account of its moderate costs and simplicity of operation. The by- product coke oven with its additional apparatus for sav- ing by- products affords many advantages in particular localities and under favorable conditions. While enormous economies may be effected in the production of coke by the recovery of the by- products which are wasted in the beehive oven, yet statistics show that less than 607o of coke manufactured today is produced in the by- product coke ovens. This fact may be readily appreciated if we are cognizant of the enormous expenditure which is required in the construction and installation of plants and equipment necessary for the recovery of these by- products. BY- PRODUCT RECOVERY’ The by- product recovery plant serves to clean the gas and to recover from it as by- products, tar, ammonia and benzols. The ammonia may be recovered either in the form of ammonia liquor or as ammonium sulphate. The hot gas from the ovens is drawn through mains to the primary coolers, where it is cooled and a certain amount of water ‘As described by The Koppers Co., Pittsburgh. 3
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and tar is condensed. This condensate carries with it a portion of the ammonia present in the gas. The gas is then drawn into ex- hausters and forced by them through tar extractors where any remaining tar is removed. From the tar extractors the gas passes to the saturators, where ammonia is removed in the form of am- monium sulphate. The gas bubbles through an acid bath in the saturator, and the intimate contact of the ammonia with the acid forms ammonium sulphate, which is precipitated as a salt. This reaction is complete, and all the ammonia remaining in the gas is recovered at this point. The gas then passes through cooling towers, where it is cooled to the proper temperature and then through scrubbers or washers where by direct contact with ab- sorbent oil, benzols are removed from the gas. After the removal of the benzols, a part of the gas is returned to the ovens for heat- ing, and the remainder is ready for distribution for use elsewhere. The ammonium sulphate formed in the saturator is pumped into drawn tables and then dried by means of centrifugal dryers. After being dried, the salt is carried to a storage pile from which it is delivered for shipment. Ammonium sulphate has many in- dustrial uses, but its most important use is as a nitrogen- carrying fertilizer. The ammonia liquor condensed in the primary coolers, to- gether with tar from coolers and tar extractors, is drained into a tank where by taking advantage of their differences in specific gravity, the two liquids are separated by decantation. The tar is pumped to a storage tank and is ready for use or shipment. To enumerate the various uses of coal tar would require avolume in itself. Among the most important, are its uses for fuel, road material, roofing material and as a base for many chemcials and dyes. The ammonia liquor is pumped also to a storage tank and from there it is taken to stills in which the ammonia vapors are driven off by treatment with steam. These vapors are piped into the stream of coke oven gas just before the saturators, and are con- verted into sulphate of ammonia in the manner just described. If it is desired, all of the ammonia can be scrubbed from the gas by the use of water, and distilled and delivered in the form of con- centrated ammonia liquor. The absorbant oil in its contact with the gas absorbs and carries away with it the benzols contained in the gas. This oil is pumped to stills and the combined benzols are driven off in aproduct known as light oil. The scrubbing oil, after it gives up its benzols, is cooled and returned to the scrubbing towers to secure more benzol. The light oil containing benzol, toluol and solvent naphtha is pumped to other stills, and these products are separated by fractional distillation. The products are then known as crude benzol, crude toluol, etc. If it is desired to make pure products, the crude products are washed with sulphuric acid to remove im- purities, and then neutralized with an alkali and redistilled Such products are then known as pure benzol, pure toluol, etc. Benzols 4
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have many important uses in the manufacture of chemicals. Toluol was in great demand during the war in the manufacture of the high explosive, tri- nitro – toluene, generally known as T.N.T. Benzol is being increasingly used as motor fuel in the place of gasoline, for it is capable of producing 2070 more mileage per gallon than gasoline. The foregoing is a brief description of the operation of a by- product coke plant. Necessarily, such a plant in its design and construction requires the efforts of all classes of engineering talent. The operation of the plant in itself is relatively simple, and aside from one or two men trained in such work, requires only ordinary labor and men capable of operating simple pieces of machinery and apparatus. Contained in the raw gases issuing from the carbonization of coal is a compound called benzol. Benzol itself is an indispensable source of nitro – benzene and aniline with its long series of deriva- tions used for dyes, drugs, photographic chemicals, etc. The manu- facture of synthetic phenol, which is a close rival of carbolic acid made directly from coal tar, may be considered as an outlet for pure benzol on account of the great increase in the production of the various condensation products of phenol and formaldehyde. From toluene is obtained such well -known products as benzalde- hyde, saccharin and benzoic acid. Metaxylene is the source of rather important series of dye. The study of other materials ob- tained in smaller amounts in coke oven benzol is believed to suggest other valuable results in the not far distant future. The Koppers Company has developed a motor fuel from coke oven gas that promises to become quite valuable for this purpose. It is claimed to give 20 to 30 per cent more power and mileage than high grade gasoline, and to cause less carbon trouble than gasoline. Owing to the rapid depletion of natural gas and the increased cost of manufacturing water gas, coke oven gas becomes of greater importance. It is claimed that coke oven gas can be substituted directly for natural gas or water gas. In the steel mills and in- dustrial plants it is used extensively in heating appliances, the chief question being where it can be used to the best advantage. Because of its high flame temperature and ease of control, and due to the claim that it is a cold, clean gas, it is used in open hearth furnaces, tube mills, soaking pits, billet- heating furnaces, annealing furnaces, galvanizing pots, brazing furnaces, etc. Coke oven gas is also being used either wholly or mixed with water gas in various cities. Coal tar recovered in by- product coking is also avaluable material from which are derived many of the basic substances used in making dyes, medicines, explosives, etc. By the process of dis- tillation various grades of oil are driven off, such as light oil, naph- thalene oil, heavy oil and anthracene oil. The residue left in the tar still is coal tar pitch, and its quality depends upon the amount of oil removed during distillation. From the above description of the physical routine for the 5
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Department Code OFFICE B1Salaries, Superintendence and Engineers 8Traveling Expenses 4Bookkeeping and Clerical Salaries 6Maintenance of Building 6Maintenance of Office Equipment 7Depreciation, Office Building 8Depreciation, Office Equipment 9Stationery and Printing 11 Toilet Repairs and Supplies 12 Heat, Light and Power 13 Telephone and Telegraph 14 Taxes 16 Insurance, Fire C1Salaries, Superintendence and Engineers 3Labor, Pumps, etc. 6Repairs to Buildings 6Repairs to Machinery and Equipment 7Depreciation, Buildings 8Depreciation, Machinery and Equipment 12 Heat, Light and Power 17 Steam 18 Small Tools 19 Lubricants, Waste and Packing 20 Miscellaneous Materials and Supplies DEPARTMENT D1Salaries, Superintendence and Engineers 2Salaries, Foreman 8Labor, Tenders, Cleaners and Stokers 4Labor, Miscellaneous 6Repairs to Buildings 6Repairs to Cranes 7Repairs to Boilers and Stacks 8Repairs to Pumps 9Repairs to Stokers 10 Repairs to Turbines, Blowers and Fans 11 Repairs to Fuel Gas Piping 12 Repairs to Steam Lines 13 Repairs to Miscellaneous Equipment 14 Depreciation, Buildings 16 Depreciation, Cranes 16 Depreciation, Boilers and Stacks 17 Depreciation, Pumps 18 Depreciation, Stokers 19 Depreciation, Turbines, Blowers and Fans 20 Depreciation, Fuel Gas Piping 21 Depreciation, Steam Lines 22 Fuel 23 Water 24 Electric Light and Power 26 Tools 26 Lubricants, Waste and Packing 27 Boiler Compound 28 Removal of Ashes and Refuse 29 Miscellaneous Supplies and Expenses
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Department Code POWER DEPARTMENT E1Salaries, Superintendence and Engineers 2Salaries, Foreman 3Labor 45Repairs to Buildings 6Repairs to Generators 7Repairs to Rotaries and Transformers 8Repairs to Feed Lines 9Depreciation, Buildings 10 Depreciation, Generators 11 Depreciation, Rotaries and Transformers 12 Depreciation, Feed Lines 13 Water 14 Steam 15 Small Tools 16 Lubricants, Waste and Packing 17 Power Purchased 18 Miscellaneous Supplies and Expenses F1Salary, Superintendence 2Salaries, Clerical 3Stationery and Printing 4Telephone and Telegraph 5Insurance, Fire 6Heat, Light and Power 7Repairs to Buildings 8Repairs to Equipment 9Depreciation, Buildings 10 Depreciation, Equipment G1Salary, Superintendence 2Labor 3Chemicals 4Miscellaneous Materials and Supplies 5Repairs to Buildings 6Repairs to Apparatus and Equipment 7Heat, Light and Power 8Miscellaneous Supplies and Expenses MACHINE, BLACKSMITH, ELECTRIC AND CARPENTER SHOPS H1Repairs to Buildings 2Repairs to Machinery and Equipment 3Water 4Steam 5Light and Power 6Small Tools 7Lubricants, Waste and Packing 8Miscellaneous Supplies and Expenses DEPARTMENT OPERATING COSTS K1Coal (proportionate part chargeable to producing coke) 2Superintendence and Clerical g
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Department Code 3Labor, Coal Conveying 4Labor, Crushing Coal 5Labor, Heating and Assistance 6Labor, Charging 7Labor, Pushing and Leveling 8Labor, Cooling and Transferring 9Labor, Coke Conveying 10 Labor, Screening and Inspecting 11 Labor, Storing 12 Labor, Loading 13 Labor, Repairing Ovens 14 Materials and Supplies, Repairing Ovens 15 Repairs to Machinery and Equipment 16 Repairs to Buildings and Grounds 17 Water 18 Steam 19 Gas (Returned to Ovens) 20 21 22 Depreciation, Ovens 23 Depreciation, Machinery and Equipment 24 Depreciation, Buildings 30 Proportion of General Overhead INCOME AND CREDIT ACCOUNTS 60 Sales, Coke (at cost if not sold) 51 Sales, Breeze (at cost if not sold) 52 Proportionate part of operating expenses charged to coke de- partment which is chargeable to production of raw materials in by- products. Note: After item 51 and item 52 has been determined, the re- mainder of the charges to department K will represent the cost of item number 50. DEPARTMENT OPERATING COSTS L1Coal (Proportionate part chargeable to production of tar as aseparate commodity) 2Proportionate part of operating expenses from coke department 3Materials and Supplies 4Salaries and Wages 5Repairs to Machinery and Equipment 6Depreciation, Machinery and Equipment 9Proportion of Plant Overhead 10 Proportion of General Overhead INCOME ACCOUNTS L20 Sales, Tar Note: If this department is charged with the total cost of tar as computed and further distillation is contemplated, the cost of tar should be credited with its derivatives at cost value. DEPARTMENT OPERATING COSTS M1Coal (Proportionate part chargeable to production of oil as aseparate commodity) 2Proportionate part of operating expenses from coke department 3Materials and Supplies 9
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Department Code 4Salaries and Wages 5Repairs to Machinery and Equipment 6Depreciation, Machinery and Equipment 9Proportion of Plant Overhead 10 Proportion of General Overhead INCOME ACCOUNTS 20 Sales, Oil Note: If this department is charged with the total cost of oil as computed and further distillation is contemplated, the cost of oil should be credited with its derivatives at cost value. OF AMMONIA DEPARTMENT OPERATING COSTS N1Coal (Proportionate part chargeable to production of sulphate of ammonia as aseparate commodity) 2Proportionate part of operating expenses from coke department 3Materials and Supplies 4Salaries and Wages 5Repairs to Machinery and Equipment 6Depreciation, Machinery and Equipment 9Proportion of Plant Overhead 10 Proportion of General Overhead INCOME ACCOUNTS 20 Sales, Sulphate of Ammonia Note: If this department is charged with the total cost of ammonia as computed and further distillation is contem- plated, the cost of sulphate of ammonia should be credited with its derivatives at cost value. DEPARTMENT OPERATING COSTS P1Coal (Proportionate part chargeable to production of gas as aseparate commodity) 2Proportionate part of operating expenses from coke department 3Materials and Supplies 4Salaries and Wages 5Repairs to Machinery and Equipment 6Depreciation, Machinery and Equipment 9Proportion of Plant Overhead 10 Proportion of General Overhead INCOME ACCOUNTS 20 Sales, Gas Note: If this department is charged with the total cost of gas as computed and further distillation is contemplated, the cost of gas should be credited with its derivatives at cost value. OPERATING COSTS R1Coal (Proportionate part chargeable to production of benzol as aseparate commodity) 2Proportionate part of operating expenses from coke department 3Materials and Supplies 4Salaries and Wages 5Repairs to Machinery and Equipment 6Depreciation, Machinery and Equipment 10
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