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On the use of caustic lime, instead of limestone, in blast furnaces
On the Use of Caustic Lime in Blast Farnaces.
329
given point is always in arrear of that of the ascending current of heated gases, and will become more so the greater the quantity of volatile matter they contained at their introduction, whether that may be of a nature to become dissipated before they arrive at a state of incandescence--such as moisture--or after having passed that point, as the gaseous and other matters evolved during the distillation of coal, and the carbonic acid from unca]cined carbona'tes. The ettbet of these combined coolinginfluenees is to allow the minerals, before they have attained a certain determinate temperature--say, that necessary for deoxidation or fusion--to be carried to a lower point in the fi2rnaee than o:herwise would be, had they not existed. Thus the zone of' fusion will have become reduced in breadth, and insufficient tbr pertbrming its fimctions without encroaching on the zone of combustion below, with all its attendant evils~scouring cinder with loss of iron, bad yields, and inferior quality. This is not all ; the supply of 2uel also reaching the blast at a correspondingly reduced temperature, is now unable to give out so great a degree of heat by its combu.~tion ; and this diminution goes on increasing for some time, t]ll an equilibrium is established. The modern domedform of blast furnace with a wide mouth, in a great measure counteracts the above defects, by etfecting the absorption of more of the heat of the ascending current of hot ga~es than can be obtained by the old conical narrow-topped furnace ; for at a certain limited depth the capacity of the lbrmer will be found fully double that of the latter; consequently presenting twice the surt~me of minerals to the action of the gases. ']'hese, also, in passin¢ through this enlarged region, move with only half the velomty, and, therefore, give double the time fbr the abstraetmn of thetr caloric. Hence it follows that by doubling the capacity of a furnace at the upper parts, or where the translbrence of heat goes on with the greatest rapidity from the continued influx of cold materials, nearlyfour times the amount is collected and carried down by the descending masses. That narrow tops consume a great deal of fuel, is an old and general complaint; and possibly the above considerations may attbrd an explanation of the cause. The theory of conduction upwards cannot be admitted~there not being the slightest analogy between the transference of heat from the bottom to the top of a filrnace, and from one end of a bar of iron to the other. The latter is a good conductor of heat while the fiJrnaee is filled with bad ores. It would take months to convey the heat through such a disintegrated mass by conduction alone ; while the passage of the gases effects it in a few seconds. Practically, the heat would never reach the top by conduction ; it would be dissipated by radiation from the sides of the furnace faster than the loose matter in its interior would take it by conduction. Ebbw Vale h'on Works, Jan. 30. •
0
,
,
•
On the Use of Caustic Lime, Instead of Limestone, in Blast Furnaces. By THO.~fASHOWELLS, Furnace .Manager.* The frequent, almost weekly, observations in your valuable paper upon the use of lime, instead of limestone, in the blast furnaces, induce me to7 • From the London Mining Journal, No. 810. 2,qo
330
.Mechanica, Physics, and Chemistry.
furnish you with particulars of the use of lime for a long period upon o u r blast furnaces at Abersychan~the result of which may be fully relied upon. In August last, our manager, in order to work off some limestones of an inferior quality, and condemned as useless, instructed me to bum some of them in one of our idle kilns, and then to use them in the :furnaces in the form of lime. I commenced putting the lime into No. 7 furnace, one charge out of four, and gradually replaced all the limestones by lime. My burden of limestone for iron of good quality was 4 cwts.; I now use of lime ~ ewts. to the charge ; and my furnace "burden" has borne an increase, without deterioration in the quality of iron produce, of from ~ cwt. to 1 cwt. to the chartge. On our No. 3 furnace, I use 1~ cwt. of lime where I used to require 3 cwts. to the charge of limestone ; and the furnace burden is increased ia proportion. I find the furnaces work in every way satisfactorily since the application of the lime, and do not observe that the use of lime in any way prejudices the quantity or quality of iron which they produce. dtbersychan, .Monraouthsldre, Feb. 26. For the Journal of the Franklin Institute,
Jl Series of Lectures on the Telegraph, deliveredbeforethe Franklin Institute. Session, 1850--51. By DR• L. TUR~BoLr.. Continued from page 274.
./1pplieation of Galvamsm to Telegraphz~.-- Mr. S. T. Sommermg, •
•
•
o
~
o~
~
°
of Munich, first applied galvanism to telegraphing; in 1809, he constructed an apparatus, which by decomposing water enabled him to give signals. At the station where the news was to arrive, were arranged thirty-five small .glass test tubes, filled with water, and reversed in a reservoir also contain. mg that fluid. Into each one of these test tubes, projected through the bottom of the reservoir the gilt end of one of thirty-five wires~ that came from the transmitting station• Each wire at the termini of the line was connected to its own distinct brass plate or cylinder. These plates were arranged in a row and perforated at one extremity; by introducing two conical metallic pinsoonnected with the poles of a voltaic btttery into these perforations, a circuit was established• Each glass tube was marked with o n e of the ~5 letters of the German alphabet, or 10 numerals, and the plate connected to it by wire at the other station, was stamped with the same. The circuit being established, the water in two of the tubes was decomposed, the gaseous constituents of which rising gave two signs, whose succession was determined by considering the letter over the evolved hydrogen as first. Decomposition of water gives twice the volume of hydrogen that it does of oxygen, and thus no mistake could well be made in dist~nguishing them. The conducting wires, well insulated, after passing some distance from the apparatus, were wound into a rope to go on totheir d~tination. Fig. 3represents Sfmmering's telegraph; A A water receiver. ql'he pointa protruding into it are shown, the glass tubes are removed, UB the apparatus to close the circuit; C the vohaic battery; single wires coming from the wire rope D have c0nnexion with file plates or cylin~[~s. Iutll the perforations of these plates the metal pencils connected
329
given point is always in arrear of that of the ascending current of heated gases, and will become more so the greater the quantity of volatile matter they contained at their introduction, whether that may be of a nature to become dissipated before they arrive at a state of incandescence--such as moisture--or after having passed that point, as the gaseous and other matters evolved during the distillation of coal, and the carbonic acid from unca]cined carbona'tes. The ettbet of these combined coolinginfluenees is to allow the minerals, before they have attained a certain determinate temperature--say, that necessary for deoxidation or fusion--to be carried to a lower point in the fi2rnaee than o:herwise would be, had they not existed. Thus the zone of' fusion will have become reduced in breadth, and insufficient tbr pertbrming its fimctions without encroaching on the zone of combustion below, with all its attendant evils~scouring cinder with loss of iron, bad yields, and inferior quality. This is not all ; the supply of 2uel also reaching the blast at a correspondingly reduced temperature, is now unable to give out so great a degree of heat by its combu.~tion ; and this diminution goes on increasing for some time, t]ll an equilibrium is established. The modern domedform of blast furnace with a wide mouth, in a great measure counteracts the above defects, by etfecting the absorption of more of the heat of the ascending current of hot ga~es than can be obtained by the old conical narrow-topped furnace ; for at a certain limited depth the capacity of the lbrmer will be found fully double that of the latter; consequently presenting twice the surt~me of minerals to the action of the gases. ']'hese, also, in passin¢ through this enlarged region, move with only half the velomty, and, therefore, give double the time fbr the abstraetmn of thetr caloric. Hence it follows that by doubling the capacity of a furnace at the upper parts, or where the translbrence of heat goes on with the greatest rapidity from the continued influx of cold materials, nearlyfour times the amount is collected and carried down by the descending masses. That narrow tops consume a great deal of fuel, is an old and general complaint; and possibly the above considerations may attbrd an explanation of the cause. The theory of conduction upwards cannot be admitted~there not being the slightest analogy between the transference of heat from the bottom to the top of a filrnace, and from one end of a bar of iron to the other. The latter is a good conductor of heat while the fiJrnaee is filled with bad ores. It would take months to convey the heat through such a disintegrated mass by conduction alone ; while the passage of the gases effects it in a few seconds. Practically, the heat would never reach the top by conduction ; it would be dissipated by radiation from the sides of the furnace faster than the loose matter in its interior would take it by conduction. Ebbw Vale h'on Works, Jan. 30. •
0
,
,
•
On the Use of Caustic Lime, Instead of Limestone, in Blast Furnaces. By THO.~fASHOWELLS, Furnace .Manager.* The frequent, almost weekly, observations in your valuable paper upon the use of lime, instead of limestone, in the blast furnaces, induce me to7 • From the London Mining Journal, No. 810. 2,qo
330
.Mechanica, Physics, and Chemistry.
furnish you with particulars of the use of lime for a long period upon o u r blast furnaces at Abersychan~the result of which may be fully relied upon. In August last, our manager, in order to work off some limestones of an inferior quality, and condemned as useless, instructed me to bum some of them in one of our idle kilns, and then to use them in the :furnaces in the form of lime. I commenced putting the lime into No. 7 furnace, one charge out of four, and gradually replaced all the limestones by lime. My burden of limestone for iron of good quality was 4 cwts.; I now use of lime ~ ewts. to the charge ; and my furnace "burden" has borne an increase, without deterioration in the quality of iron produce, of from ~ cwt. to 1 cwt. to the chartge. On our No. 3 furnace, I use 1~ cwt. of lime where I used to require 3 cwts. to the charge of limestone ; and the furnace burden is increased ia proportion. I find the furnaces work in every way satisfactorily since the application of the lime, and do not observe that the use of lime in any way prejudices the quantity or quality of iron which they produce. dtbersychan, .Monraouthsldre, Feb. 26. For the Journal of the Franklin Institute,
Jl Series of Lectures on the Telegraph, deliveredbeforethe Franklin Institute. Session, 1850--51. By DR• L. TUR~BoLr.. Continued from page 274.
./1pplieation of Galvamsm to Telegraphz~.-- Mr. S. T. Sommermg, •
•
•
o
~
o~
~
°
of Munich, first applied galvanism to telegraphing; in 1809, he constructed an apparatus, which by decomposing water enabled him to give signals. At the station where the news was to arrive, were arranged thirty-five small .glass test tubes, filled with water, and reversed in a reservoir also contain. mg that fluid. Into each one of these test tubes, projected through the bottom of the reservoir the gilt end of one of thirty-five wires~ that came from the transmitting station• Each wire at the termini of the line was connected to its own distinct brass plate or cylinder. These plates were arranged in a row and perforated at one extremity; by introducing two conical metallic pinsoonnected with the poles of a voltaic btttery into these perforations, a circuit was established• Each glass tube was marked with o n e of the ~5 letters of the German alphabet, or 10 numerals, and the plate connected to it by wire at the other station, was stamped with the same. The circuit being established, the water in two of the tubes was decomposed, the gaseous constituents of which rising gave two signs, whose succession was determined by considering the letter over the evolved hydrogen as first. Decomposition of water gives twice the volume of hydrogen that it does of oxygen, and thus no mistake could well be made in dist~nguishing them. The conducting wires, well insulated, after passing some distance from the apparatus, were wound into a rope to go on totheir d~tination. Fig. 3represents Sfmmering's telegraph; A A water receiver. ql'he pointa protruding into it are shown, the glass tubes are removed, UB the apparatus to close the circuit; C the vohaic battery; single wires coming from the wire rope D have c0nnexion with file plates or cylin~[~s. Iutll the perforations of these plates the metal pencils connected