Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1990-05-08
1991-09-17
Kastler, S.
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
148 16, C21D 148
Patent
active
050491857
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a method for supplying with a lance a liquid to a heat-treatment oven, the liquid being vaporized by the oven heat and, with the assistance of carrier gas, introduced into the oven, and a lance for carrying out the method.
Heat treatment of steel of relatively high carbon content, for example annealing of ball-bearing steel, normally takes place in large ovens or furnaces with carefully regulated treatment atmosphere and temperature. The atmosphere normally consists substantially of nitrogen, with an addition of carbon monoxide and hydrogen. For correcting the carbon activity of the steel, use is made of additives of propane or air, depending upon the nature of the deviation.
The addition of hydrogen and carbon monoxide is normally effected by an addition of methanol which, in the oven, at a temperature of approx. 700.degree. C. or higher, is thermally broken down into carbon monoxide and hydrogen. The methanol is supplied using a lance which is inserted in a channel through the oven wall.
A prior-art lance consists of a tube which is inserted in the oven wall and which thereby directs a jet of methanol towards the opposite wall. Thereupon, a portion of the methanol which is not thermally broken down before the jet reaches the opposite wall will impinge upon the wall and give rise to soot formation on the oven wall.
Another prior-art lance fundamentally consists of two concentric tubes, of which the outer is inserted further into the oven wall than the inner. Methanol is supplied to the inner tube and a carrier gas, normally nitrogen, is supplied to the annular space between the outer surface of the inner tube and the inner surface of the outer tube. The methanol in the inner tube is vaporized by the heat of the oven in the downstream end of the inner tube. The nitrogen from the annular space which, at the downstream end of the inner tube, merges into a circular chamber in which the inner tube discharges entrains the vaporized methanol and disseminates it more uniformly in the interior of the oven.
The disadvantage inherent in the first-described lance will be obvious to the skilled reader and primarily consists of soot formation on that oven wall which faces the lance. The disadvantage inherent in the second prior-art lance is primarily that the lance cannot be inserted a sufficient distance into the oven wall, since thermal breakdown may occur even before the methanol has departed from the lance. As a result, the lance cannot be inserted a sufficient distance into the channel of the oven wall, in order to avoid the risk that methanol impinges upon the channel wall.
One object of the present invention is to obviate the drawbacks described in tho foregoing in the employment of the prior-art lances and, thereby, to devise a method of supplying a substance which is liquiform at ambient temperature, preferably methanol, to a heat-treatment oven using a lance, such that the risk is avoided that methanol impinges on the channel wall of the oven in which the lance fs inserted, or on the opposing wall.
A further object of the present invention is to realize a method of obtaining more uniform distribution than has hitherto been possible of a liquid in vapour form in a heat-treatment oven.
Yet a further object of the present invention is to realize a lance for practical implementation of the method.
These objects will be attained by a method characterized in that the liquid is atomized in a carrier gas in an end of a lance facing away from the interior of the oven, that the atomized liquid and carrier gas are supplied to a vaporization chamber with an outlet which is directed towards the interior of the oven, in which chamber the atomized liquid is vaporized by the oven heat during simultaneous cooling of the chamber; and that the thus formed vapour and carrier gas are caused to depart from the vaporization chamber of the lance through the aperture acting as a nozzle, the lance employed in reducing the method into practice being characterized by a vaporization chamber w
AGA Aktiebolag
Kastler S.
LandOfFree
Method and arrangement for supplying liquid to an oven does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and arrangement for supplying liquid to an oven, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and arrangement for supplying liquid to an oven will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1914519