Metallurgical apparatus – Means for introducing fluent into vessel – e.g. – tuyere – Having means preventing damage to introducing means – e.g.,...
Patent
1988-12-29
1990-03-27
McDowell, Robert
Metallurgical apparatus
Means for introducing fluent into vessel, e.g., tuyere
Having means preventing damage to introducing means, e.g.,...
266218, G21C 548
Patent
active
049114140
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to sealing injection apparatus for use to inject substances into molten metals.
We have been developing apparatus and methods for introducing substances through the wall or bottom of a vessel, such as a ladle, deep into metal melt therein. Such substances include gases, powders, solids and mixtures thereof. In principle, the chosen substance is fed along a metal lance pipe loosely fitted in passage in a refractory, injection nozzle block. The loose fit permits the lance pipe to be moved forcefully along the passage, to break or dislodge a closure installed at an inner, melt end of the passage, thereby gaining access to the melt for initiating injection of the substance. See, for example, our International Patent Publication No. W084/02147, the contents of which are incorporated herein by this reference.
The loose fit also allows the pipe and passage to be flushed with a selected gas before injection commences. Generally, the gas is passed along the inside of the pipe. Before injection is started, the closure prevents the flushing gas entering the melt, so it travels back along the outside of the pipe in the clearance space in the passage, and then exhausts to the atmosphere. Besides expelling unwanted air from the passage and pipe, the flushing step permits the operator to establish the gas conditions appropriate for efficacious injection into the melt, before injection is activated. See, for instance our International Patent Publication No. WO 87/05051published on 27 Aug. 1987, the contents of which are incorporated herein by this reference.
As also disclosed in International Patent Publication No. WO 87/05051, the flushing step cools the lance pipe. Moreover, the loose fit is designed to allow the melt to penetrate and freeze in the clearance space. This is beneficial because the frozen melt locks the lance pipe in the passage and counters any tendency of the metallostatic pressure in the vessel to thrust the lance pipe outwards of the passage.
Once injection has commenced, it is desired to constrain the injection gas to enter the melt and to preclude it from escaping and exhausting to the atmosphere. To meet this desire, we provide a sealing means between the lance pipe and the outer end of the passage, operative when the lance is advanced to its injection position. An example of a sealing means is shown incidentally in FIG. 8 of the drawings of our International Patent Publication No. WO 88/00246published on 14 Jan. 1988, but is not explicitly described therein. Another example of such a sealing means is illustrated and described in our International Patent Publication No. WO 88/00247 published on 14Jan. 1988. This sealing means (35) comprises a metal sleeve (36) having a flared mouth fitted in the outer end of the passages and metal collar (38) immovably fixed on the lance pipe. A seal is attained on advancing the lance pipe when the collar and sleeve abut and interfit.
As aforesaid, melt runs back along the lance pipe, (in the clearance space). This happens apparently instantaneously upon initiating injection. Usually, the melt travels only a limited distance before freezing in the clearance space. With most metals, e.g. steel, the melt does not run back the entire length of the lance. However, we have observed that in the case of some melts, usually those that are very limpid, the run back may be very rapid and extensive. Superheated molten iron (superheat of 200.degree.C.) is one example. This can run back as far as the sealing means. Without being bound by incompletely-understood hypothesis, we think this may be caused by the metallostatic head acting in conjunction with a pressure shock wave which may be generated in the clearance space as flushing becomes injection upon initiating injection.
If molten particles reach the sealing means, they may damage the sealing means and prevent proper sealing. Moreover, they may spray out of the passage if they reach its end before the collar has reached its sealing position. Furthermore, the injection apparatus is fabricated fro
REFERENCES:
patent: 1793849 (1931-02-01), Groninger
patent: 3971548 (1976-07-01), Folgero et al.
patent: 4771992 (1988-09-01), King
Bates Kenneth W.
Dixon Peter R.
Toyn John G.
Ingersoll Buchanan
Injectall Limited
McDowell Robert
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