From the data of furnace practice of forty-two openhearth furnaces in ecah works, the relations between the furnace capacity, productive power and fuel value were traced out, and further the merits of using molten pig iron with scrap were studied. The conclusions are summarised below:-
(1) The productive power of steel increases as the capacity of open-hearth furnace and is almost independent to the variety of fuels or charges. If we take x and v as the productive power of steel per hour and the capacity of the furnace respectively, their relation can be represented by the following equations
(constant)
where t is the refining time per ton of steel.
(2) The productive power of steel increases as the calorific power of fuel generated in the furnace in unit time and is independent of the variety of fuels.
(3) The refining time per ton of steel is inversely proportional to the calorific power of fuel in unit time. The refining time of cold charge is always longer than that of mixed charge with molten pig iron, when the same calorific power is generated in the furnace in unit time.
(4) The calorific power for refining about one ton of steel is reduced in an inverse ratio to the capacity of furnace.
(5) The more steel is produced per hour, the less fuel cosumption per ton of steel is effected.
(6) The fuel consumption per ton of steel diminishes as the increase of furnace capacity, almost independently of charge.
(7) In the mean value, the use of molten pig iron for the charge saves 409·5×103 kilocalories per ton. This calorific value corresponds to 2·55 times the heat content in one ton of molten pig iron.
(8) The heat loss per ton of steel due to waste gas, rediation and conduction increases as the refining time, and consequently as the heat cosumption per ton of steel, almost independently of the variety of charges or fuels, and diminisheds as the increase of furnace capacity.
(9) The heat loss due to the foregoing three causes diminishes linearly as the increase of steel production per hour, independent of the variety of charges.
(10) The total heat quantity contained in one of molten steel and its corresponding slag is almost always equal to 429×105 kilocalories and is indepen lent of the furnace capacity, variety of fuels and the refining time, so that it will be seen, even from this point, that the shortening of refining time brings the saving of fuel consumption.
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