WO2023064312A1

WO2023064312A1 - Single support and single penetration stave coolers

Info

Publication number: WO2023064312A1
Application number: PCT/US2022/046334
Authority: WO
Inventors: Allan J. Macrae
Original assignee: Macrae Technologies, Inc.
Priority date: 2021-10-11
Filing date: 2022-10-11
Publication date: 2023-04-20

Abstract

A stave cooler with a body of cast copper in which are fully disposed a number of independent loops of cooling pipes of CuNi/NiCu only, and each loop having an inlet end and an outlet end fitted with a stainless steel (SS) coupler, and all of which inlet and outlet ends and SS couplers are turned up together for external access in a single grouping. A single steel ribbon band or steel collar opened at two opposite ends, is attached, filled in by, or captured to the body panel of cast copper such that the single grouping of inlet and outlet ends and SS couplers are partially or fully filled inside and made accessible for external coolant hose connections. The steel ribbon band, if filled inside, or the steel collar if not filled inside supports the entire weight of the stave cooler inside a furnace shell through a one-per-stave penetration of the furnace shell. The inlet and outlet ends are externally accessible for coolant connections.

Description

SINGLE SUPPORT AND SINGLE PENETRATION STAVE COOLERS

CROSS-REFERENCE TO RELATED APPLICATIONS

This present application is an International Patent Application claiming priority to US Patent Application No. 17/450,536, filed October 11, 2021, entitled SINGLE SUPPORT AND SINGLE PENETRATION STAVE COOLERS, which is a continuation in part of US Patent Application No. 16/634,878, filed January 28, 2020, entitled METHODS FOR MANUFACTURING HIGH HEAT FLUX REGIME COOLERS, which is a National Stage Entry of International Patent Application No. PCT/US 19/38752, filed June 24, 2019, entitled HIGH HEAT FLUX REGIME COOLERS, which is a continuation-in-part of US Patent Application No. 16/443,474, filed June 17, 2019, entitled FURNACE BRICKS, COOLERS, AND SHELL S/B INDINGS OPERATING IN SYSTEMIC BALANCE, now issued as US Patent No. 10,533,802, which is a divisional of US Patent Application No. 16/422,909, filed May 24, 2019, entitled METHODS FOR MANUFACTURING COPPER BLOCK COOLERS, now abandoned, which is a continuation-in-part of US Patent Application No. 16/290,922, filed March 3, 2019, entitled WATER PIPE COLLECTION BOX AND STAVE COOLER SUPPORT, now issued as US Patent No. 10,954,574, which is a continuation-in-part of US Patent Application No. 16/272,662, filed February 11, 2019, entitled PLATE COOLER STAVE APPARATUS AND METHODS FOR FERROUS OR NON-FERROUS METAL MAKING FURNACE, now abandoned, which is a continuation-in-part of US Patent Application No. 13/148,003, filed December 23, 2011, entitled PANEL FOR FERROUS OR NON-FERROUS METAL MAKING FURNACE, which is now issued as US Patent No. 10,247,477, which claims priority from US Provisional Patent Application No. 61/319,089, filed March 30, 2010, entitled PANEL FOR FERROUS OR NON-FERROUS METAL MAKING FURNACE, the disclosures of which are incorporated herein in their entireties. FIELD OF INVENTION

The present invention relates to stave coolers for circular furnaces with steel containment shells, and more particularly to cast-copper stave coolers with a single penetration required of a steel containment shell.

BACKGROUND

Steel and non-ferrous metals are being smelted throughout the world in circular furnaces with steel containment shells. Some of these employ panel type stave coolers that completely line the interior walls to cool refractory bricks mounted to their hot faces. Their individual cooling actions are delivered by liquid coolants that circulate inside each stave cooler with piping that passes through penetrations of the steel containment shells to access an external heat exchanger. Each penetration of the steel containment shell requires reliable welds and seals to keep the hazardous process gases both inside the furnace and away from its operating personnel.

Production rates exceeding three tons of hot metal per cubic meter of working volume per day are now being reached with modern blast furnaces. This was made possible by using improved burden materials, better burden distribution techniques, tighter process controls, very high hot-blast temperatures, oxygen enrichment technology, pulverized-coal injection, and natural gas fuel enrichment. All of which result in much higher average heat loads and fluctuations that land on the stave coolers mounted inside the steel containment shells of up-to-date blast furnaces.

Integrated steelworks use blast furnaces to supply themselves the pig iron they use to make steel. The large gains being made in furnace-productivity have also placed overwhelming demands on cooling system capacities. The liquid-cooled stave coolers in blast furnaces first developed in the late 1960's became inadequate. Pure-copper stave coolers have been needed since the late 1970's because these are better able to deal with the intense process heats now being generated in state-of-the-art, high stress furnaces. Copper stave coolers have also proved themselves capable of delivering furnace campaign lives that now exceed fifteen years.

The average thermal load levels a stave cooler will be subjected to depends on where it will be positioned within a blast furnace. See Fig. 1. Cast-iron staves can still be successfully used in the less demanding middle and upper stack areas of blast furnaces, but the much higher average heat loads below in the lower stack, Belly, Bosh, Tuyere Level, and Hearth all require the use of higher performing, but more costly copper staves.

Cast iron staves are less efficient at cooling than are copper staves because the cast iron metal is relatively much lower in thermal conductivity. Their inherent thermal resistance allows heat to pile up too high if too much loading is presented. Poor internal boding can add unnecessarily to the overall thermal resistance. Otherwise, cracks develop in the internal cast iron and the cracking can propagate into the steel pipes themselves. Cast iron staves have a de-bonding layer that adds to a thermal barrier between coolants circulating in its water-cooling tubes and the hot faces of the cast iron stave body. Both such effects conspire in reducing the overall heat transfer abilities of cast iron staves.

Such inefficiencies in cast iron stave heat transfer performance can drive hot face temperatures over 700° C. That hot, thermal deformations in cast iron staves are hard to avoid with such overstressing. Cast iron stave bodies can also suffer phase-volume transformations when operated at very elevated temperatures. Fatigue cracking, stave body material spalling, and cooling pipes exposed directly to the furnace heat are common failures. Stave coolers can also be used in reduction vessels for the production of direct reduced iron (DRI).

Towards these ends, stave coolers must depend entirely for their vertical mechanical support by a single hanging of the through-bulkhead in a single corresponding penetration of the containment shell. Carrying only "much of the load" leaves the door open to more than one penetration of the steel containment shell per stave cooler. The two jobs of supporting the stave cooler's weight, and connecting all the coolant piping, must always be shared in a single through-bulkhead neck.

SUMMARY

Briefly, cast-copper stave cooler embodiments of the present invention include a body of cast copper in which are fully disposed a number of independent loops of cooling pipes of CuNi/NiCu only, and each loop having an inlet end and an outlet end fitted with a stainless steel (SS) coupler, and all of which inlet and outlet ends and SS couplers are turned up together for external access in a single grouping. A single steel ribbon band or steel collar opened at two opposite ends, is attached, filled in, or captured by the body panel of cast copper such that the single grouping of inlet and outlet ends and SS couplers are partially or fully filled inside and made accessible for external coolant hose connections. The steel ribbon band, if filled inside, or the steel collar if not filled inside supports the entire weight of the stave cooler inside a furnace shell through a one-per-stave penetration of the furnace shell. The inlet and outlet ends are externally accessible for coolant connections.

SUMMARY OF THE DRAWINGS

Fig. 1 represents a perspective view diagram of a stave cooler that was originally disclosed as Figs. 5 and 7 by the Present Inventor, Allan J. MacRae, and Todd G. Smith on 12/23/2011, in Application 13/148,003, now US 10,247,477. The same was also originally disclosed in a CIP of the first also as Figs. 5 and 7 by the Present Inventor, Allan J. MacRae, and Todd G. Smith on 02/11/2011, in Application 16/272/662, Patent Application Publication US 2019/0170439, and still pending;

Fig. 2 represents a perspective view diagram a stave cooler in a mutation of the stave cooler of Fig. 1;

Fig. 3 represents a perspective view diagram a stave cooler in a mutation of the stave cooler of Fig. 2;

Fig. 4 represents a perspective view diagram a stave cooler in a mutation of the stave cooler of Fig. 3; and

Fig. 5 represents a perspective view diagram a stave cooler in a mutation of the stave cooler of Fig. 4.

DETAILED DESCRIPTION

Fig. 1 represents a new perspective view of a stave cooler 100 that was originally disclosed as Figs. 5 and 7 by the Present Inventor, Allan J. MacRae, and Todd G. Smith on 12/23/2011, in Application 13/148,003, now US 10,247,477. The same was also originally disclosed in a CIP of the first also as Figs. 5 and 7 by the Present Inventor, Allan J. MacRae, and Todd G. Smith on 02/11/2011, in Application 16/272/662, Patent Application Publication US 2019/0170439, and still pending. There was much more to be said about such stave coolers in those Figs. 5 and 7 than we divulged at the time.

Stave cooler 100 is further limited herein to a cast body 102 limited to only copper, a plurality independent piping loops 104 limited to only thin-wall CuNi/Ni/Cu, a plurality of pipe couplers 106 limited to only stainless steel (SS), a corresponding number of inlets/outlets 108 to couple outside a steel containment shell, a fill neck 112 limited to only being a portion of casting of body 102, and a band/collar 110 limited to only carbon steel formed in a thin steel ribbon band, or a thick frame collar.

The band/collar 110 is not a strap. It is a continuous ribbon of steel inside of which neck 112 is cast. The two cannot weld or bond together because copper and steel are not conducive for such.

The limitations of the cast body 102 to only copper, and the plurality piping loops 104 to only thin-wall CuNi/Ni/Cu, enable the respective alloys to fuse together and form an inseparable bond. Such bonding occurs during a no-oxygen environment casting of the body 102 with preheated and cleaned scrubbed piping loops 104 inside.

The plurality piping loops 104 are limited to only thin-wall CuNi/Ni/Cu, such as Schedule 40, allows the piping loops 104 to be arraigned tightly together with minimum radii. This aids with even cooling.

The ordinary inlets/outlets 108 of piping loops 104 must be supported by the pipe couplers 106. And those must be of stainless steel, both to avoid contaminating the surrounding copper fill, and to present a strong enough material to attach coolant pipes and hoses.

The neck 112 need not protrude from band/collar 110. If it doesn't, a steel cover can be added to seal process gases inside a steel containment shell. The band/collar 110 is continuously perimeter welded around an aperture in the steel containment shell during final installation. Hanging on the steel containment shell, the band/collar 110 will support all the weight of stave cooler 100.

If the band/collar 110 is larger in cross section than the body 102, stave cooler 100 can be slipped into the aperture in the steel containment shell from outside. If the band/collar 110 is not larger in cross section than the body 102, stave cooler 100 can be slipped into the aperture in the steel containment shell from its inside.

Stave cooler 100 is preferably laterally curved to better fit a cylindrical steel containment shell. (Such curvature is slight and not readily discernable in Fig. 1.)

Fig. 2 represents a stave cooler 200 in a mutation of stave cooler 100. Its cast copper body 202 is extended up and a neck 204 and a steel band/collar 20 6 are moved down. Two circuits of coolant pipes 208 would also loop around inside the extension of body 202 to provide even cooling throughout. The configuration of coolant pipes 208 is such that no part of them will suffer from hot spots, film boiling, or collapse from melting.

Stave cooler 200 mounts from only inside a steel containment shell.

Fig. 3 represents a stave cooler 300 in a mutation of stave cooler 200. A cast copper body 302 has been flowed up and into a neck 304 during casting and solidified. An independent network of coolant pipes 306 was also placed inside and solidified inside body 302 at a fixed, predetermined position to optimize and level heat evacuation by a coolant flow during use. Such fixed, predetermined position is calculated in CFD/FEA computer modeling in iterative simulations.

Fig. 4 represents a stave cooler 400 in a mutation of stave cooler 300 that was developed over years. It includes four independent loops 402 of CuNi/Ni/Cu piping in more or less equal lengths, diameters, and flow rates/pressure drops. A steel collar 404 has one end embedded inside stave cooler 400. A steel cover 406 has eight holes in a 2x4 matrix to accommodate the inlet/outlet ends a pipe coupler inside steel collar 404.

The steel cover 406 provides a way to gas seal process gases when continuously welded.

The whole of stave cooler 400 hangs onto a corresponding opening in a steel containment shell 408.

Figs. 5A and 5B represent a stave cooler 500 in a mutation of stave cooler 400. A cast copper panel 502 includes an interior pipe circuit 508 with up-turned inlets/outlets 509. The interior pipe circuit 508 consists here of four independent loops 510-513. These all turn up through steel anchor frame 604 with inlets/outlets 509 through a steel anchor frame 514. The inlets/outlets 509 all end in stainless steel (SS) couplers 516.

Figs. 6A-6D represent a stave cooler 600 in a mutation of stave cooler 500. A copper body 602 is laterally curved with coolant pipe circuits emerging as inlet/outlet ends 606. These connect to SS thimble sleeves 608 inside a steel collar 610. A cover plate 612 seals the insides. Eight SS couplers 614 are used to connect to external hoses. A steel adapter plate 616 is welded on outside the containment shell.

Although particular embodiments of the present invention have been described and illustrated, such is not intended to limit the on-going invention. Modifications and changes will no doubt become apparent to those skilled in the art, and it is intended that the invention only presently be limited by the scope of the appended claims.

Claims

1 . A stave cooler, comprising: a stave body of cast copper only in which are fully disposed a number of independent loops of cooling pipes of CuNi/NiCu only, and each loop having an inlet end and an outlet end only, and each fitted with a coupler, and all of which inlet and outlet ends and couplers are turned up together for external access in a single grouping; a single ribbon band or steel collar of steel only and opened at two opposite ends, and in casting, attached, filled in, or otherwise captured by the stave body of cast copper such that the single grouping of inlet and outlet ends and couplers is filled inside and the inlet and outlet ends are accessible for external coolant hose connections; wherein, the steel ribbon band or the steel collar is configured to support the entire weight of the stave cooler inside a furnace shell when passed through a one- per-stave penetration of the furnace shell and continuously welded together external to a steel only containment shell around a perimeter of the band or collar for a gas-tight seal, and that thereby makes the single grouping of inlet and outlet ends externally accessible for coolant plant connections passing through inside the perimeter; wherein the cooling pipes and the single grouping of inlet and outlet ends are thereby less susceptible to cracking and water leaks over a campaign life.

2 . The stave cooler of Claim 1, further comprising: two independent loops only of cooling pipes wherein each is configured to remove the same amount of heat as the other from any incoming heat flux on a hot face of the stave body.

3 . A plate cooler stave for use in an iron-making furnace that has a carbon steel containment shell, comprising:

8 a main body of cast iron or cast copper and that includes a top portion in which are disposed a number of pairs of cooling fluid inlets and outlets; a number of independent loops of cooling fluid circulating tubes of thin wall, copper or steel, piping and fittings only that are embedded in the main body, and wherein each independent loop ends in one pair of cooling fluid inlets and outlets; a single carbon steel band embracing or fixed into the top portion that is weldable around its outside perimeter to an opening defined by the carbon steel containment shell; wherein, the main body is insertable into and externally exposed by its top portion and single carbon steel band into the furnace from the inside only through the opening defined by the carbon steel containment shell.

4 . The plate cooler stave of Claim 3, further comprising: a carbon steel cover plate used to install the plate cooler stave, and that is configured to weld to and prevent process gas leakage from within the furnace shell by covering the opening after installation of the plate cooler stave; wherein, the routes and positionings of the number of independent loops of cooling fluid circulating tubes are configured within the plate cooler stave to provide uniform cooling of the furnace.

5 . The plate cooler stave of Claim 4, further comprising: a hole in the carbon steel cover plate that is sized to fit around and continuously be welded inside around its inner perimeter to an outer perimeter of the carbon steel band.

6 . The plate cooler stave of Claim 3, further comprising: a carbon steel cover plate that is attached to the top portion and that is securable to a wall of the carbon steel containment shell.

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7 . The plate cooler stave of Claim 4, wherein: the carbon steel cover plate is attached to the top portion, and is configured to be gas-sealed by welding to a wall of the carbon steel containment shell.

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