WO1998042456A1

WO1998042456A1 - Apparatus and method for reducing consumption of alcohol used in cleaning oxidized hot metal surfaces

Info

Publication number: WO1998042456A1
Application number: PCT/US1998/006206
Authority: WO
Inventors: Milton Edward Berry
Original assignee: Southwire Company
Priority date: 1997-03-27
Filing date: 1998-03-26
Publication date: 1998-10-01
Also published as: DE69819108T2; DE69819108D1; EP0914217A1; EP0914217A4; EP0914217B1

Abstract

An apparatus and method for reducing consumption of a cleaning solution used in cleaning oxidized hot metal surfaces of continuously cast and rolled metal rod are disclosed. A blast of air is applied to the metal surface with an airwipe device (36) so as to remove droplets of the solution used in cleaning the oxidized metal surface, the removed droplets are collected in an enclosure or box (18), and are received and recovered in a storage tank (20). A liquid trap (19) is provided in a drain connecting the box (18) to the storage tank (20) so as to prevent exhaustion of air into the storage tank (20) and carrying away of volatile components of the cleaning solution.

Description

APPARATUS AND METHOD FOR REDUCING CONSUMPTION OF ALCOHOL USED IN CLEANING OXIDIZED HOT METAL SURFACES

Field of the Invention The present invention generally relates to an apparatus and method for reducing consumption of alcohol used in cleaning oxidized hot metal surfaces. For example, the invention can be employed in an apparatus for continuous cleaning or pickling of cast and rolled copper rod.

Description of the Prior Art

Hot-rolled copper or copper alloy rod used in the manufacture of wire is usually formed into coils for convenient handling. The rod accumulates a surface scale or oxide when exposed to the atmosphere, and this scale should be completely removed before the rod is used in the manufacture of wire. In the prior art, the surface scale or oxide has been typically removed from the surface of copper base products by the common practice of "pickling" the products, that is, contacting their surfaces with a "pickling" liquid such as a solution including sulfuric acid, nitric acid, or other acids. Such methods and apparatus are disclosed in the following U.S. patents, which are assigned to the assignee of the present invention: 3,623,532; 4,005,744; and 4,181,091.

In more recent times, alternatives to "pickling" using acid solutions have been developed. Such alternative solutions are necessitated by the operating costs associated with the requirement to use acid-resistant materials, to avoid ecological problems associated with waste acid disposal, and to produce a more consistent and better quality product. One such alternative has involved the use of organic reducing agents, such as alcohol, aldehydes, ketones and organic acids. However, the use of such agents must be carefully controlled to avoid adverse effects on the environment.

Therefore, more modern methods and apparatus have involved the collection of the cleaning mixture (or reducing agent mixture) vapors and the conveyance of the collected vapors to a central point for concentration and condensation. Such a method and apparatus are disclosed in U.S. Patent No. 4,899,798, which is assigned to the assignee of the present invention.

Thus, alcohol is often used to chemically reduce the oxidized surface of continuously cast and rolled hot copper and copper alloy metal products. Such alcohol is in an aqueous solution typically of about 3 % alcohol. After the reduction process, small quantities of the alcohol solution remain on the surface of the moving rod, and are usually removed with on or more blasts of air provided by an "airwipe" apparatus. In such methods and apparatus of the prior art, alcohol droplets removed from the rod as a result of the airwipe drain into a solution recovery tank for further disposition and/or recycling and reuse.

However, in the prior art apparatus, a portion of the air utilized in the airwipe device passes out through the drain of the airwipe enclosure into the recovery tank, and sweeps across the surface of the alcohol liquid in the tank thereby removing volatile alcohol from the tank. Since this alcohol-laden air must be treated before disposal to the external atmosphere, e.g., by thermal destruction or condensation of the alcohol, there results a substantial loss of alcohol. Prior to the present invention, about 50% of the alcohol used in the cleaning process was lost due to this phenomenon. Thus, there is a significant need for a method and apparatus which solves this disadvantageous situation in the prior art apparatus and method.

Summary of the Invention

The present invention generally relates to an apparatus and method for reducing the consumption of alcohol used in cleaning oxidized hot metal surfaces. More particularly, the invention accomplishes that function in a method and apparatus for continuously quench-pickling cast and rolled copper and copper alloy rod in a continuous casting and rolling process. Essentially, the invention accomplishes the desired objective by providing a liquid trap in the drain line between the airwipe enclosure or box and the storage or recovery tank. This liquid trap separates the airwipe air from the liquid alcohol solution according to the typical function of a water trap.

For the apparatus disclosed, the amount of alcohol solution contacted by the airwipe air is only that small amount of alcohol solution which is carried over from the pickling or cleaning tube into the airwipe, and the small surface of the liquid trap. To meet environmental requirements, the airwipe air discharged via the normal vent tubes from the airwipe box may still require treatment by condensation of the alcohol or thermal destruction of the alcohol. However, the quantity of alcohol carried by this air is insignificant compared to the total amount of alcohol being used and the amount of volatile alcohol carried out of the recovery tank by the air discharged into the tank in the prior art apparatus.

Therefore, it is a primary object of the present invention to provide an apparatus and method for reducing the consumption of alcohol used in pickling or cleaning oxidized hot metal surfaces.

It is an additional object of the present invention to provide an apparatus and method wherein a liquid trap is provided in the drain line between the airwipe box and the storage or recovery tank to separate air from the alcohol solution.

The above and other objects, and the nature of the invention, will be more clearly understood by reference to the following detailed description, the associated drawings, and the appended claims.

Brief Description of Drawings

Figure 1 is a diagrammatic representation of an apparatus for the pickling or cleaning of continuously cast and rolled rod in accordance with the present invention. Figure 2 is a side elevation view in cross-section of the airwipe box employed in the apparatus of Figure 1. Figure 3 is an end elevation view partly in cross-section taken along line IQ- III of Figure 2 of the airwipe box employing a liquid trap in accordance with the present invention.

Detailed Description of the Invention

The invention will now be described in more detail with reference to the various figures of the drawings.

Figure 1 is a diagrammatic representation of an apparatus for the pickling or cleaning of continuously cast and rolled rod in accordance with the present invention. As seen therein, the apparatus 10 comprises a cleaning pipe or tube 12 and various spray boxes 14a-14h positioned at predetermined intervals along the length of the pipe 12, as well as a drain box 16 positioned at an intermediate point along the pipe 12. The apparatus 10 also includes an airwipe assembly 17 with a plurality of airwipe boxes 18 disposed at the downstream end of the pipe 12, as well as pinch rolls 22 through which the rod passes prior to being delivered to a conventional rod coiler (not shown). Finally, the apparatus 10 includes a storage or recovery tank 20 connected to the airwipe boxes 18 of the airwipe assembly 17 via one or more drains employing a liquid trap 19.

In operation, the rod being processed passes through the pipe 12, and successively past spray boxes 14a-14h. Spray boxes 14a-14h spray the rod with a cleaning solution (e.g., a 3 % aqueous alcohol solution), and the drain box 16 is provided at an intermediate point of the pipe 12 for draining off excess solution.

Once the rod passes through each of the spray boxes 14a-14h, it enters the first airwipe box 18 where it is subjected to a blast of air at a pressure of from about 1 atm. to about 10 atm. for the purpose of removing solution droplets from the surface of the rod. These droplets are drained off via liquid trap 19 to storage or recovery tank 20. The resulting rod, with the alcohol droplets removed, passes between pinch rolls 22 and is conveyed to a rod coiler (not shown) where it is formed into coils for further disposition or transport.

In the airwipe boxes 18, air preferably enters the pipe 12 in such a manner as to flow in a direction opposite, i.e., countercurrent, to the direction of travel of the metal rod. Moreover, the blast of air introduced into pipe 12 passes through a relatively small gap between the airwipe housing and the outer surface of the metal rod, effectively removing droplets of cleaning solution from the surface of the metal rod in the process. The droplets of cleaning solution fall to the bottom of the airwipe boxes 18 and are drained through trap 19 into storage or recovery tank 20. Figure 2 illustrates one airwipe box 18 employed in the apparatus of Figure

1 , and Figure 3 is an end view of that box taken along line III-III of Figure 2 showing the liquid trap 19 in accordance with the present invention. As seen therein, airwipe box 18 includes air vent pipes 30 and 32, a threaded rod guide 34 mounted on the upstream side of box 18 with a slotted nut 34a, a conventional airwipe 36, liquid drain pipes 38 and 40, rod exit opening 42, and an air inlet 44 connected to the airwipe 36.

In operation, the metal rod (not shown) enters airwipe box 18 via guide 34 and passes from left to right in Figure 2, emerging from box 18 via exit opening 42. An air blast is injected into airwipe 36 via air inlet 44. Preferably, the air blast is directed circumferentially about the rod and flows in a direction from right to left in

Figure 2, that is, in a direction opposite to the direction of travel of the metal rod.

As a result of being subjected to the blast of air, droplets of cleaning solution adhering to the outer surface of the metal rod are removed, fall downwardly to the bottom of the airwipe box 18, and are drained off via drain pipes 38 and 40. As mentioned previously, a particular problem with the prior art apparatus is that some of the air injected through inlet 44 passes through pipes 38 and 40. As a result, such air flows across the large surface area of liquid solution collected in the storage/recovery tank 20 (Figure 1), and this results in the removal and loss of large quantities of volatile alcohol collected in the space over the solution in the tank 20. The inventive arrangement disclosed herein provides a solution to this problem. Specifically, in accordance with the invention, a liquid trap 19 is connected to drain pipes 38 and 40. As seen in Figure 3, the liquid trap 19 is preferably in the shape of oppositely connected U-shaped tubes according to a common design of water traps . As a result of the configuration of the liquid trap 19, air cannot escape through pipe 40 due to the fact that liquid solution collected in the trap fills the trap 19 to some level indicated by the dashed lines 56 in Figure 3. Thus, liquid collected in the trap 19 prevents the air in box 18 from exhausting through drain pipes 38 and 40, flowing into tank 20, and disadvantageously removing volatile alcohol from tank 20. As a result, the present invention achieves substantial savings in the overall cleaning process because of the retention of most of the collected cleaning solution. It has been found that, as a result of implementation of the present invention, loss of cleaning solution (such as alcohol) is substantially eliminated whereas, in arrangements of the prior art, approximately 50% of the cleaning solution was lost as a result of air passing out of box 18 into and through storage/recovery tank 20. The inventive arrangement also has advantages from the environmental standpoint in that, when alcohol is used as a cleaning solution, the essential elimination of evaporation of alcohol results in drastic cutback in the emission or exhaustion of alcohol into the external atmosphere.

Although certain presently preferred embodiments of the present invention have been specifically described herein, it will be apparent to those skilled in the art to which the invention pertains that variations and modifications of the various embodiments shown and described herein may be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the invention be limited only to the extent required by the appended claims and the applicable rules of law.

Claims

What Is Claimed Is:

1. Apparatus for reducing consumption of a solution used in cleaning an oxidized metal surface, comprising: airwipe means for applying a blast of air to the metal surface so as to remove droplets of the solution used in cleaning the oxidized metal surface; drain means for carrying the removed droplets away from the metal surface; recovery means connected to said drain means for receiving the removed droplets carried away from the metal surface; and trap means disposed in said drain means for preventing the exhaustion of air from said airwipe means into said recovery means.

2. The apparatus of claim 1 , wherein said trap means comprises a liquid trap including a first portion connected to said drain means and extending in a downward direction, a second portion connected to an end of said first portion remote from said drain means and extending in an upward direction, and a third portion connected to an end of said second portion remote from said first portion and extending in the downward direction.

3. The apparatus of claim 1 , including a plurality of said airwipe means each airwipe means having trap means in the drain means connected to the recovery means.

4. The apparatus of claim 1, wherein said cleaning solution is aqueous alcohol.

5. The apparatus of claim 1, wherein said metal surface is a copper rod surface.

6. The apparatus of claim 1 , wherein said blast of air comprises air at a pressure of from about 1 atm. to about 10 atm.

7. A method for reducing consumption of a solution used in cleaning an oxidized metal surface comprising the steps of: applying a blast of air to the metal surface with an airwipe so as to remove droplets of the solution used in cleaning the oxidized metal surface; collecting the removed droplets in an enclosure surrounding the airwipe; draining the collected droplets from the enclosure through a drain and into a storage tank; and preventing the exhaustion of air from the enclosure into the storage tank.

8. The method of claim 7 , wherein said preventing step comprises providing a liquid trap in the drain between the enclosure and the storage tank.

9. The method of claim 8, wherein said preventing step further comprises collecting the removed droplets in the liquid trap so as to block the exhaustion of air into the storage tank.

10. The method of claim 7, wherein said blast of air comprises air at a pressure of from about 1 atm. to about 10 atm.

11. Apparatus for cleaning an oxidized metal surface of a continuously cast and rolled metal rod comprising a cleaning pipe through which said rod travels, means for introducing a cleaning solution having volatile components into the pipe into contact with the metal surface of the rod, airwipe means downstream of the pipe for wiping the solution from the rod surface with a blast of air, means for collecting the solution wiped from the rod surface, tank means for storing the collected solution, drain means for draining the solution from the collecting means into the tank means, and trap means disposed in the drain means for preventing air from the airwipe means from flowing into the tank means and carrying off the volatile components from the cleaning solution in the tank means.

12. The apparatus of claim 11, wherein said blast of air comprises air at a pressure of from about 1 atm. to about 10 atm.

13. The apparatus of claim 11, wherein said metal rod is a copper rod.

14. The apparatus of claim 11 , wherein said cleaning solution is aqueous alcohol.