GB1585732A - Cooled tubular members in metallurgical furnaces - Google Patents

Description

(54) COOLED TUBULAR MEMBERS IN METALLURGICAL FURNACES (71) We, VSESOJUZNY NAUCHNO ISSLEDOVATELSKY I PROEKTNY INSTITUT PO OCHISTKE TEKHNOLOGICHESKIKH GAZOV STOCHNYKH VOD I ISPOLZOVANIJU VTORICH NYKH ENERGORESURSOV PREDPRIYATY CHER NOI METALLURGII (VNIPICHERMETENER- GOOCHISTKA), of prospekt Lenina 9, Kharkov, Union of Soviet Socialist Republics, a corporation organised and existing under the laws of the Union of Soviet Socialist Republics, 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 present invention relates to the design of cooled tubular members in metallurgical furnaces.

One known metallurgical furnace includes straight cooled pipes representing a product-supporting structure made up of long (up to 25 m) horizontal sections with an inside diameter of up to 200 mm.

Accommodated coaxially in the interior of the pipes (if they are over 90 mm in diameter) are inserts (metallic rods or plugged tubes), making it possible to bring down the flow rate of a circulating coolant (the mass of a coolant flowing through the cross-sectional area of the pipes per unit time), and to improve the cooling conditions of the pipes. In the prior-art construction the gap between the outside surface of the insert and inside surface of the pipe in which the insert is accommodated remains the same throughout the pipe length.

What is desired is a design of cooled tubular members which will make it possible to improve cooling efficiency and extend the service life of the members owing to a reduction in flow resistance in the coolant flowing zone with a substantial vapour content, to increase the rate of circulation to improve heat transfer conditions in the zone where boiling of water occurs at the internal surface of the tube, and to eliminate the possibility of stratification into steam and water in the boiling zone. Another desire is to enhance the operating reliability of the tubular members by eliminating the possibility of insert displacement and obviating a considerable number of welded joints. A specific aim is to reduce metal requirements for pipelines running to an evaporative cooling plant.

Yet another no less important aim is to provide a reduction in power consumption for plants with forced coolant circulation.

The present invention provides a metallurgical furnace including tubular members through which a coolant is to flow, the tubular members comprising straight pipes, the interior of each pipe accommodating a coaxial insert diminishing in cross-section in the direction of coolant flow.

Such constructional arrangement of the insert makes it possible to reduce the flow resistance in the zone with substantial vapour contents, thereby providing for enhanced cooling efficiency, to improve cooling conditions and to extend the service life of the tubular members.

It is expedient that the insert be made of abutting parts, which facilitates manufacture thereof, particularly when the length of the insert exceeds 10 m.

It is preferable for the gap between the outside surface of the insert and the inside surface of the pipe in which it is accommodated to vary in the range between 12 and 30 mm. This assures a higher coolant flow rate and a better cooling efficiency for sections which are arranged where the cooling conditions are most arduous and which are most frequently subjected to damage, and maintains a sufficient coolant flow rate in other sections.

It is advisable for the straight pipes to be coupled in pairs by bent connecting pipes and for an insert to be arranged con cordantly to the longitudinal axis of the connecting pipe and abutted against the inserts accommodated in the straight pipes, the abutted pipes being made with the same diameters, and the abutted inserts also having the same diameters at their junctions.

Such a design provides a coolant flow in which any vapour is more finely dispersed and provides better cooling conditions for the straight pipes adjoining the bent connecting pipes. The use of a heated bent connecting pipe ensures better cooling conditions and more reliable operation.

It is sound practice for the junction between each straight cooled pipe and a bent connecting pipe to be displaced relative to the place of connection of its insert with that accommodated in the bent connecting pipe. This ensures easy manufacture and mounting of the inserts.

Each pair of said inserts can be abutted against each other by way of a metallic stud and a recess provided respectively in the abutted ends of the inserts. Such an embodiment ensures convenient mounting and dismounting of the tubular members with bent connecting pipes.

The invention will be described further, by way of example only with reference to the accompanying drawings, in which: Figure 1 shows cooled tubular members in a metallurgical furnace, with cut-away sections (partial section of pipes through the longitudinal axis); Figure 2 depicts a straight pipe with an insert and a stud at its junction with a bent connecting pipe and a recess provided in an insert in the bent connecting pipe (partial section through the longitudinal axis); and Figure 3 illustrates a straight pipe and a connecting pipe and inserts with centering studs accommodated therein (partial longitudinal section of the pipe).

Referring now to the drawings and to Figure 1 in particular, there is shown therein one of a plurality of cooled tubular members in a metallurgical furnace. The tubular member comprises straight pipes 1 and 2, the interior 3 of each pipe accommodating respective coaxial inserts 4 and 5 made with a cross-section diminishing in the direction of the coolant flow (as indicated by arrow A). To enable more convenient fabrication the insert 5 is made up of two parts 6 and 7 abutted against each other. Between the outside surface of the insert 4 and inside surface of the pipe 1 in which the insert 4 is accommodated, there is provided a gap 8 which may vary in the range between 12 and 30 mm depending on the coolant parameters.

The two straight pipes 1 and 2 are coupled with a bent connecting pipe 9 accommodating an insert 10 running along the pipe longitudinal axis. The inserts 4 and 5 in the pipes 1 and 2 are abutted against the insert 10 in the connecting pipe 9, the abutted pipes 1, 2, and 9 being similar in diameter.

The junction 11 between each straight cooled pipe 1 and 2 and bent connecting pipe 9 is displaced relative to the junction 12 between the insert 5 and insert 10 accommodated in the bent connecting pipe 9, the inserts 5 and 10 having the same diameters or cross-sections (where use is made of the inserts having other than circular configuration) at their junction 12.

The junction (not visible) between the inserts 4 and 10 is also displaced from the pipe junctions 11.

To enable more convenient mounting and dismounting operations while abutting the inserts 5 and 10 which are accommodated respectively in the pipes 2 and 9, a stud such as shown at 13 in Figure 2 is provided on the insert 5 and a recess 14 in the insert 10, adapted to receive the stud 13.

For aligning the inserts 5 and 10 use is made of studs 15 such as shown in Figure 3, arranged at intervals on the outside surface of the inserts 5 and 10. The furnace has several cooled tubular members consisting of pairs of straight pipes 1 and 2 interconnected with a pipe 9, the pairs being similar to that described above.

The cooling of each tubular member takes place in the following manner. A coolant is fed in the direction of arrow A into the annular gap 8 (see Figure 1) between the straight pipe 1 and the insert 4.

The tubular member can be considered as comprising three sections in the direction of the coolant flow. The first one comprises the part of the straight pipe 1 into which is flowing a coolant below its boiling point.

The coolant commences to boil also in that section. The second section includes a zone of moderate boiling of the coolant, this zone comprising the end of the first straight pipe 1, the bent connecting pipe 9, and the beginning of the straight pipe 2. The third section constitutes a zone wherein the coolant has a great vapour content; it comprises the central portion and the end of the straight pipe 2.

In accordance with the above-described subdivision of the pipes 1, 9, and 2 and the inserts 4, 10, and 5, the gap 8 between the corresponding inside wall of the cooled pipes 1, 9, and 2 and outside surfaces of the inserts 4, 10, and 5 ranges for the first section from 12 to 18 mm, for the second, from 18 to 25 mm, and for the third one from 25 to 30 mm.

In this case the ratio between the inside diameter of the straight pipes and the out side diameter of the inserts varied in the following ranges: between 1.2 and 1.4 for the first section; between 1.4 and 1.6 for the second one; and between 1.6 and 2.0 for the third section.

Test results have proved the effectiveness of engineering solutions followed in the above-described cooled tubular members, the possibility of diminishing materially the hydraulic resistance and enhancing the coolant flow rate in the first section.

Optimum coolant rates can be achieved at minimum values of hydraulic resistances along with an increased circulation flow rate and better cooling efficiency.

Moreover, it is possible to employ cooling systems with remote drums for separating vapour and liquid, maintain a constant flow area of the bent connecting pipe, which is of paramount importance for its reliable functioning, and cut down the number of welded joints in the junction between the straight and bent connecting pipes, which is likewise extremely important insofar as the evaporative cooling systems of metallurgical furnaces operate at a pressure of up to 45 atm. g. and are subjected to considerable dynamic loads.

WHAT WE CLAIM IS: 1. A metallurgical furnace including tubular members through which a coolant is to flow, the tubular members comprising straight pipes, the interior of each pipe accommodating a coaxial insert diminishing in cross-section in the direction of coolant flow.

2. A furnace as claimed in claim 1, wherein the insert is made up of parts abutted against each other.

3. A furnace as claimed in claims 1 or 2, wherein the gap between the outside surface of an insert and the inside surface of the pipe which accommodates it varies in the range between 12 and 30 mm.

4. A furnace as claimed in any of claims 1 to 3, wherein the straight pipes are coupled in pairs, the pipes of each pair being coupled by a bent connecting pipe accommodating an insert running along its longitudinal axis and abutted against the inserts in the straight pipes, the straight pipes and the bent pipes having the same diameters, the abutted inserts being of the same diameter at their junctions.

5. A furnace as claimed in claim 4, wherein the junction between a straight pipe and the bent connecting pipe is shifted relative to the junction between the insert in the straight pipe and that in the bent connecting pipe.

6. A furnace as claimed in claim 4 or 5, wherein the inserts are abutted by way of a metallic stud and a recess provided at the respective abutitng ends.

7. A metallurgical furnace including tubular members substantially as described herein with reference to, and as shown in, the accompanying drawings.

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. side diameter of the inserts varied in the following ranges: between 1.2 and 1.4 for the first section; between 1.4 and 1.6 for the second one; and between 1.6 and 2.0 for the third section. Test results have proved the effectiveness of engineering solutions followed in the above-described cooled tubular members, the possibility of diminishing materially the hydraulic resistance and enhancing the coolant flow rate in the first section. Optimum coolant rates can be achieved at minimum values of hydraulic resistances along with an increased circulation flow rate and better cooling efficiency. Moreover, it is possible to employ cooling systems with remote drums for separating vapour and liquid, maintain a constant flow area of the bent connecting pipe, which is of paramount importance for its reliable functioning, and cut down the number of welded joints in the junction between the straight and bent connecting pipes, which is likewise extremely important insofar as the evaporative cooling systems of metallurgical furnaces operate at a pressure of up to 45 atm. g. and are subjected to considerable dynamic loads. WHAT WE CLAIM IS:

1. A metallurgical furnace including tubular members through which a coolant is to flow, the tubular members comprising straight pipes, the interior of each pipe accommodating a coaxial insert diminishing in cross-section in the direction of coolant flow.

2. A furnace as claimed in claim 1, wherein the insert is made up of parts abutted against each other.

3. A furnace as claimed in claims 1 or 2, wherein the gap between the outside surface of an insert and the inside surface of the pipe which accommodates it varies in the range between 12 and 30 mm.

4. A furnace as claimed in any of claims 1 to 3, wherein the straight pipes are coupled in pairs, the pipes of each pair being coupled by a bent connecting pipe accommodating an insert running along its longitudinal axis and abutted against the inserts in the straight pipes, the straight pipes and the bent pipes having the same diameters, the abutted inserts being of the same diameter at their junctions.

5. A furnace as claimed in claim 4, wherein the junction between a straight pipe and the bent connecting pipe is shifted relative to the junction between the insert in the straight pipe and that in the bent connecting pipe.

6. A furnace as claimed in claim 4 or 5, wherein the inserts are abutted by way of a metallic stud and a recess provided at the respective abutitng ends.

7. A metallurgical furnace including tubular members substantially as described herein with reference to, and as shown in, the accompanying drawings.