GB1600491A

GB1600491A - Cooling of blast furnaces

Info

Publication number: GB1600491A
Application number: GB196877A
Authority: GB
Original assignee: Carblox Ltd
Current assignee: Carblox Ltd
Priority date: 1977-01-18
Filing date: 1977-01-18
Publication date: 1981-10-14
Also published as: FR2377451A1; DE2713353A1

Description

(54) AN IMPROVEMENT IN OR RELATING TO COOLING OF BLAST FURNACES (71) We, CARBLOX LIMITED, a British Company, of Storrs Bridge Works, Loxley, Sheffield 6, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to cooling of blast furnaces and has for its object to provide an improvement therein. In particular, it concerns an improved method of providing underfloor cooling in a blast furnace.

Heretofore, when building a blast furnace which is to have underfloor cooling it has been customary to lay conduits for circulating cooling water or air between support members on which a substantial metal plate or other impermeable member has been laid to guard against the possibility of water or air leaking upwards from the conduits into the refractory furnace hearth.

In another method of building a blast furnace, where it is required to extract heat from the base but air or water pipes are not required or desired, a course of high conductivity graphite is used as the bottom course of the hearth pad. Heat from the pad is conducted through the graphite to the shell (or coolers) and is extracted by water cooling.

It is normal practice to thermally connect the graphite to the shell (or staves) by means of a ramming material. Ihis method of cooling is not as efficient as air or water cooling, but does of course eliminate water or air from the inside of the furnace.

According to one - aspect of the invention, there is provided a method of cooling a blast furnace, the method involving the use of heat pipes (that is to say low pressure boiling/ condensing units), said heat pipes extending underneath the furnace hearth and/or into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace.

When the method involves the use of heat pipes extending into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace, said heat pipes may be vertically or substantially vertically disposed and may be embedded in steel or cast iron blocks. When the method involves the laying of heat pipes beneath the hearth, these may be laid within a heat conducting medium surrounding the heat pipes to facilitate heat transfer from the hearth to said heat pipes.

The method may include the connection of portions of the heat pipes projecting outwardly from the furnace to heat transfer apparatus located wholly outside the furnace.

According to a further aspect of the invention, there is provided a blast furnace with cooling means constituted by a plurality of heat pipes (that is to say low pressure, boiling/ condensing units) extending underneath the furnace hearth and/or into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace. Heat pipes which extend into the furnace wall and/ or into the bosh and/or into the barrel and/or into the stack of the furnace may be vertically or substantially vertically disposed and may be embedded in steel or cast iron blocks. Heat pipes located beneath the furnace hearth may be laid within a heat conducting medium facilitating heat transfer from the hearth to said heat pipes. Portions of the heat pipes which extend outwardly from the furnace may be connected to heat transfer apparatus located wholly outside the furnace.In this case, the heat transfer apparatus may include respective heat exchange chambers surrounding the outwardly projecting portions of the heat pipes, flow and return pipes being connected into said heat exchange chambers for the circulation of cooling water therethrough.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which: Fig. 1 is a vertical section through the lower wall portion of a blast furnace embodying the invention, Fig. 2 is a fragmentary plan view thereof.

Fig. 3 is a diagrammatic view of a so-called heat pipe, and Fig. 4 is a view similar to Fig. 1 of the lower wall portion of a different construction of blast furnace.

Referring now to Figs. 1 and 2 of the draw-.

ings, the blast furnace there illustrated includes a steel shell 10 and a hearth composed of carbon blocks 12 laid on a flat floor composed of tiles 14 accurately placed on a castable material 16.

The furnace is provided with underfloor cooling means constituted by a plurality of socalled heat pipes, generally indicated 20, extending as shown through the shell of the furnace and beneath the furnace hearth. As shown, the heat pipes are laid on a base cast able material 18 and have been covered by a high conductivity ramming material 19 which is arranged to draw heat from beneath the hearth and pass it into the heat pipes. Each heat pipe is a sealed, low pressure, boiling/ condensing tubular unit utilizing capillary action for condensate return to an evaporator (heat input) section from a condenser (heat removal) section. Such units, previously, available under the trade name SOLEK, are now available under the trade name ISOTERIX.

A heat pipe is illustrated diagrammatically in Fig. 3 and is shown to include a hollow tube 22 with closed ends and a lining material constituting a wick 24. The tube has been evacuated of air and a quantity of a suitable working fluid has been introduced into the tube before it has been sealed.

Outwardly projecting portions of the heat pipes 20, that is to say their condenser (heat removal) sections, are connected to heat transfer apparatus, illustrated purely diagrammatically in the drawing and generally indicated 26, which includes respective heat exchange chambers 28 which surround said outwardly projecting portions of the heat pipes and which are provided with flow and return pipes 30 and 32 for the circulation of cooling water therethrough.

By virtue of the fact that the heat transfer apparatus 26 through which the cooling water is circulated is located wholly outside the furnace it has been possible to omit the substantial metal plate or other impermeable member usually built into such a furnace as a barrier against the leakage of water or air upwards into the refractory furnace hearth and it will be understood that this represents a considerable saving of cost. It will also be understood that should a heat pipe require replacement or repair it can be withdrawn through the shell of the furnace and a new one fitted, possibly with a coating of a material ensuring good thermal contact with the floor into which it extends.

Referring now to Fig. 4, this illustrates the incorporation of the invention in a blast furnace the hearth of which is differently consuucted.

The furnace hearth in this case is shown to be composed of a flat floor of carefully laid tiles 34, an overlying layer of graphite blocks 36, and a topmost layer of carbon blocks 38.

A high thermal conductivity ramming material 40 (for example flake graphite) is used to fill the space between the graphite or carbon blocks and the steel shell 10.

In this case, the heat pipes 20 extend through the furnace shell and into the graphite layer substantially midway of its thickness. Although not shown in the drawing, the heat pipes will be surrounded by a heat conducting medium to facilitate heat transfer from the graphite blocks to the heat pipes.

Various modifications may be made without departing from the scope of the invention. For example, the condenser (heat removal) sections of the heat pipes could be finned to promote good heat transfer to the cooling water.

Their evaporator (heat input) sections could be differently arranged for maximum heat transfer from the ramming material in which they are set; for example they could be welded to a metal plate or respective plates disposed beneath the ramming material, or between the courses of graphite or carbon blocks as the case may be, although this would of course interfere with the subsequent removal and replacement of the heat pipes through the furnace shell, or they could extend into metallic sleeve elements welded to such a metal plate or such respective plates. The required number and spacing of the heat pipes and their size to achieve the required rate of cooling of the furnace hearth may of course be determined by calculation and experiment by persons skilled in the art.

It will be seen that in the example illustrated the heat pipes extend in parallel across the furnace floor. However, it will be understood that, if preferred, they could extend radially outwards from the centre or from regions near the centre of the furnace floor.

It will also be understood that in addition to the furnace hearth being cooled by means of heat pipes in the manner described the same method may be adopted for the cooling of other regions of the furnace, for example by heat pipes extending into the furnace wall, the bosh, the barrel and the stack, but of course in these cases the heat pipes may need to be laid not horizontally but vertically and may need to be embedded in steel or cast iron blocks.

WHAT WE CLAIM IS: 1. A method of cooling a blast furnace, the method involving the use of heat pipes (that is to say low pressure boiling/condensing units), said heat pipes extending underneath the furnace hearth and/or into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace.

2. A method according to claim 1 of cooling a blast furnace, and involving the use of heat

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. heat pipe, and Fig. 4 is a view similar to Fig. 1 of the lower wall portion of a different construction of blast furnace. Referring now to Figs. 1 and 2 of the draw-. ings, the blast furnace there illustrated includes a steel shell 10 and a hearth composed of carbon blocks 12 laid on a flat floor composed of tiles 14 accurately placed on a castable material 16. The furnace is provided with underfloor cooling means constituted by a plurality of socalled heat pipes, generally indicated 20, extending as shown through the shell of the furnace and beneath the furnace hearth. As shown, the heat pipes are laid on a base cast able material 18 and have been covered by a high conductivity ramming material 19 which is arranged to draw heat from beneath the hearth and pass it into the heat pipes. Each heat pipe is a sealed, low pressure, boiling/ condensing tubular unit utilizing capillary action for condensate return to an evaporator (heat input) section from a condenser (heat removal) section. Such units, previously, available under the trade name SOLEK, are now available under the trade name ISOTERIX. A heat pipe is illustrated diagrammatically in Fig. 3 and is shown to include a hollow tube 22 with closed ends and a lining material constituting a wick 24. The tube has been evacuated of air and a quantity of a suitable working fluid has been introduced into the tube before it has been sealed. Outwardly projecting portions of the heat pipes 20, that is to say their condenser (heat removal) sections, are connected to heat transfer apparatus, illustrated purely diagrammatically in the drawing and generally indicated 26, which includes respective heat exchange chambers 28 which surround said outwardly projecting portions of the heat pipes and which are provided with flow and return pipes 30 and 32 for the circulation of cooling water therethrough. By virtue of the fact that the heat transfer apparatus 26 through which the cooling water is circulated is located wholly outside the furnace it has been possible to omit the substantial metal plate or other impermeable member usually built into such a furnace as a barrier against the leakage of water or air upwards into the refractory furnace hearth and it will be understood that this represents a considerable saving of cost. It will also be understood that should a heat pipe require replacement or repair it can be withdrawn through the shell of the furnace and a new one fitted, possibly with a coating of a material ensuring good thermal contact with the floor into which it extends. Referring now to Fig. 4, this illustrates the incorporation of the invention in a blast furnace the hearth of which is differently consuucted. The furnace hearth in this case is shown to be composed of a flat floor of carefully laid tiles 34, an overlying layer of graphite blocks 36, and a topmost layer of carbon blocks 38. A high thermal conductivity ramming material 40 (for example flake graphite) is used to fill the space between the graphite or carbon blocks and the steel shell 10. In this case, the heat pipes 20 extend through the furnace shell and into the graphite layer substantially midway of its thickness. Although not shown in the drawing, the heat pipes will be surrounded by a heat conducting medium to facilitate heat transfer from the graphite blocks to the heat pipes. Various modifications may be made without departing from the scope of the invention. For example, the condenser (heat removal) sections of the heat pipes could be finned to promote good heat transfer to the cooling water. Their evaporator (heat input) sections could be differently arranged for maximum heat transfer from the ramming material in which they are set; for example they could be welded to a metal plate or respective plates disposed beneath the ramming material, or between the courses of graphite or carbon blocks as the case may be, although this would of course interfere with the subsequent removal and replacement of the heat pipes through the furnace shell, or they could extend into metallic sleeve elements welded to such a metal plate or such respective plates. The required number and spacing of the heat pipes and their size to achieve the required rate of cooling of the furnace hearth may of course be determined by calculation and experiment by persons skilled in the art. It will be seen that in the example illustrated the heat pipes extend in parallel across the furnace floor. However, it will be understood that, if preferred, they could extend radially outwards from the centre or from regions near the centre of the furnace floor. It will also be understood that in addition to the furnace hearth being cooled by means of heat pipes in the manner described the same method may be adopted for the cooling of other regions of the furnace, for example by heat pipes extending into the furnace wall, the bosh, the barrel and the stack, but of course in these cases the heat pipes may need to be laid not horizontally but vertically and may need to be embedded in steel or cast iron blocks. WHAT WE CLAIM IS:

1. A method of cooling a blast furnace, the method involving the use of heat pipes (that is to say low pressure boiling/condensing units), said heat pipes extending underneath the furnace hearth and/or into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace.

pipes extending into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace, in which said heat pipes are vertically or substantially vertically disposed.

3. A method according to either one of the preceding claims of cooling a blast furnace, in which heat pipes extending into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace are embedded in steel or cast iron blocks.

4. A method according to any one of the preceding claims of cooling a blast furnace, the method involving the laying of heat pipes beneath the hearth within a heat conducting medium surrounding the heat pipes to facilitate heat transfer from the hearth to said heat pipes.

5. A method according to any one of the preceding claims, of cooling a blast furnace, the method including the connection of portions of the heat pipes projecting outwardly from the furnace to heat transfer apparatus located wholly outside the furnace.

6. A blast furnace with cooling means constituted by a plurality of heat pipes (that is to say low pressure, boiling/condensing units) extending underneath the furnace hearth and/or into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace.

7. A blast furnace according to claim 6, in which heat pipes which extend into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace are vertically or substantially vertically disposed.

8. A blast furnace according to either one of claims 6 and 7, in which heat pipes which extend into the furnace wall and/or into the bosh and/or into the barrel and/or into the stack of the furnace are embedded in steel or cast iron blocks.

9. A blast furnace according to any one of claims 6 to 8, in which heat pipes located beneath the furnace hearth are laid within a heat conducting medium facilitating heat transfer from the hearth to said heat pipes.

10. A blast furnace according to any one of the claims 6 to 9, in which portions of the heat pipes which extend outwardly from the furnace are connected to heat transfer apparatus located wholly outside the furnace.

11. A blast furnace according to claim 10, in which the heat transfer apparatus includes respective heat exchange chambers surrounding the outwardly projecting portions of the heat pipes, flow and return pipes being connected into said heat exchange chambers for the circulation of cooling water therethrough.

12. A method of cooling a blast furnace, substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

13. A blast furnace, constructed and arranged substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

1600491 COMPLETE SPECIFICATION 2 SHEETS This drawing Is a reproduction of the Original on a reduced scale Sheet 2

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