Process and installation for the continuous application of an oxidizable coating to a strip
AssigneeZiegler S.A.
InventorsJean-Paul Hennechart, Bernard Bramaud, Francois Prat
Life of this patent
Estimating the term…
Abstract
A process and an installation for the continuous application of an oxidizable coating to a strip. The object of the invention is to provide an improvement in the recycle ratios and a savings of inert replenishing gas in an installation, in the enclosure which protects the draining means for controlling the coating, is recycled. To achieve this result, provision is made for the continuous purification of this gas by bringing it into contact with a reductive substance. If protective enclosure also contains the minimized flouring nozzles, zinc vapor can be introduced into the gas. This zinc vapor reacts with the oxygen and produces the nuclei by condensation.
Claims18
A process for the continuous coating of a strip with an oxidizable coating material comprising the steps of:
- causing the strip to enter and pass through a bath containing the coating material in the liquid state, causing the strip to leave the bath in an ascending direction, equalizing the liquid coating material thickness carried by the strip, said equalizing operation being carried out in an enclosure substantially isolated from an atmosphere external to said enclosure and containing a first non-oxidizing or weakly oxidizing gas, said first gas being at least partially recycled and purified by bringing the gas into contact with a reducing substance to bring its oxygen content below a preselected value, the gas to be purified being reacted with a reducing substance of the hydrocarbon type, introduced in a small quantity, on a hot surface comprising a heated plate or a coated sheet.
An installation comprising means for successively causing a strip to enter and pass continuously through a molten bath of coating material and causing said strip to leave the bath in an ascending direction;
- means for equalizing the thickness of the layer of liquid coating material carried by the strip, said equalizing means being arranged inside an enclosure open towards the bottom and having side walls which dip into the bath and having an upper wall provided with a narrow slit through which the strip can leave, said enclosure being associated with a gas circuit having means for recycling a first gas from said enclosure;
- at least one blast nozzle for cooling the strip below a solidification point of the coating material;
- means for introducing a reducing substance into said circuit for recycling said first gas;
- and means for bringing said first gas to a temperature at which the reducing substance reacts with the oxygen contained in the gas to bring its concentration below a selected value, the means for introducing the reducing substance into the gas and bringing the latter to the reaction temperature consists of an enclosure through which the gas passes and which contains a bath of reducing substance in the liquid state and a plasma torch, arranged about this bath, for vaporizing the substance.
Dependencies are inferred from the claim text.