GB2120373A

GB2120373A - Hot blast stoves

Info

Publication number: GB2120373A
Application number: GB08313312A
Authority: GB
Inventors: Horst Kalfa; Dr Hans-Eugen Buhler
Original assignee: Didier Werke AG
Current assignee: Didier Werke AG
Priority date: 1982-05-14
Filing date: 1983-05-13
Publication date: 1983-11-30
Also published as: DE3218125C1; JPS58207306A; GB8313312D0; GB2120373B; FR2526811A1; NL8301648A

Abstract

A hot blast stove for a blast furnace plant includes a burner, a heat exchanger and an outer sheet metal casing. The metal casing is associated with protective means or is so disposed that it is substantially not subject to changes in the climate. Changes in the temperature of the sheet metal casing are thus reduced and stress corrosion of the casing minimised. The protective means may be a weather shield or wind deflector, for example.

Description

SPECIFICATION Hot blast stoves The present invention relates to hot blast stoves for a blast furnace plant and to a blast furnace plant including such a hot blast stove.

Such hot blast stoves generally include an outer sheet metal casing and it is an object of the invention to eliminate or substantially reduce stress corrosion of this casing.

According to the present invention a hot blast stove for a blast furnace plant includes a burner, a heat exchanger and an outer sheet metal casing, the metal casing being associated with protective means or being so disposed that it is substantially not subject to changes in the climate. The changes in the climate which are of particular concern are changes in the wind direction and strength, temperature or rain conditions since these can cause differences in the temperature of the exterior of the sheet metal casing.

The invention utilises the realisation that temperature differences caused by climatic effects on the exterior of the sheet metal casing result in undesirable stress corrosion. The proposal of the present invention eliminates or substantially reduces such temperature differences.

Hot blast stoves include a burner and a heat exchanger and these may either be arranged together within a single sheet metal casing or they may constitute separate but connected components each of which is within a respective sheet metal casing. In the event that the hot blast stove has two sheet metal casings it is preferred that they are both protected from changes in climatic effects and it is preferred also that the connecting pipes and those leading to the blast furnace are also so protected. The proposal of the present invention is applicable not only to new hot blast stoves but also to the subsequent modification of existing hot blast stoves which may not be disconnectable from the plant whilst in operation.

The sheet metal shell may be arranged so as to be shielded from the weather by other parts of the blast furnace plant or it may be provided with special wind deflectors. The wind deflector is preferably disposed adjacent the sheet metal shell or mounted on it as a baffle or guard plate. A special rain shield may also be associated with the sheet metal shell and if both a wind deflector and a rain shield are provided they may be constructed as a shed-like modification of the sheet metal shell.

The wind deflector and/or the rain shield may be made from thin metal or plastics plates. They may alternatively be constituted by organic or inorganic coatings. In contrast to known insulating means, the protective measures of the present invention do not aim to avoid stress corrosion by the temperature of the heat metal shell exceeding the condensation point.

It is also possible to dispose the hot blast stove initially at geographical locations where the climatic effects such as the wind, temperature and rain, or changes therein are relatively slight.

The accompanying drawings illustrate the problem with which the present invention is concerned in more detail. Figure 1 represents a vectorial addition of the wind strength and direction to be expected at the site of a hot blast stove, reference numerals 1 to 7 indicating winds blowing from the North-West, West, South-West, South, East, North-East and North respectively whilst reference numeral 8 represents the vectorial addition or resultant of these. Figure 2 is a schematic representation of a blast furnace installation including a blast furnace 12 to which two hot blast stoves are connected, each of which comprises a heat exchange. 10 and a combustion shaft 11 within a respective sheet metal shell.

Figure 3 is a graphical representation of the crack frequency or concentration, shown on the Y axis, at various points on the shell of one of the combustion shafts. The positions of these points on the shell are indicated angularly with reference to the scale shown adjacent Figure 2 with respect to the resultant or primary wind direction illustrated in Figure 1. Figure 3 can thus be considered as showing the crack concentration on a development of the sheet metal shell of a combustion shaft.

1. A hot blast stove for a blast furnace plant including a burner, a heat exchanger and an outer sheet metal casing, the metal casing being associated with protective means or being so disposed that it is substantially not subject to changes in the climate.

2. A hot blast stove as claimed in Claim 1 in which the metal shell is disposed adjacent a weather shield, particularly a wind shield, such as other parts of the plant or specially provided wind deflectors.

3. A hot blast stove as claimed in Claim 2 in which the wind deflector is disposed in the proximity of the metal shell or mounted on the metal shell as a baffle or guard plate.

4. A hot blast stove as claimed in any one of Claims 1 to 3 including a rain shield associated with the metal shell.

5. A hot blast stove as claimed in Claims 2 and 4 in which the wind deflector and rain shield are constructed as a shed-like modification of the metal shell.

6. Protective arrangement as claimed in Claim 3 or Claim 4, in which the wind deflector and the rain shield are made from metal or plastics plates.

7. A hot blast stove as claimed in any one of the preceding claims which is arranged at a geographical location where the wind,

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Hot blast stoves The present invention relates to hot blast stoves for a blast furnace plant and to a blast furnace plant including such a hot blast stove. Such hot blast stoves generally include an outer sheet metal casing and it is an object of the invention to eliminate or substantially reduce stress corrosion of this casing. According to the present invention a hot blast stove for a blast furnace plant includes a burner, a heat exchanger and an outer sheet metal casing, the metal casing being associated with protective means or being so disposed that it is substantially not subject to changes in the climate. The changes in the climate which are of particular concern are changes in the wind direction and strength, temperature or rain conditions since these can cause differences in the temperature of the exterior of the sheet metal casing. The invention utilises the realisation that temperature differences caused by climatic effects on the exterior of the sheet metal casing result in undesirable stress corrosion. The proposal of the present invention eliminates or substantially reduces such temperature differences. Hot blast stoves include a burner and a heat exchanger and these may either be arranged together within a single sheet metal casing or they may constitute separate but connected components each of which is within a respective sheet metal casing. In the event that the hot blast stove has two sheet metal casings it is preferred that they are both protected from changes in climatic effects and it is preferred also that the connecting pipes and those leading to the blast furnace are also so protected. The proposal of the present invention is applicable not only to new hot blast stoves but also to the subsequent modification of existing hot blast stoves which may not be disconnectable from the plant whilst in operation. The sheet metal shell may be arranged so as to be shielded from the weather by other parts of the blast furnace plant or it may be provided with special wind deflectors. The wind deflector is preferably disposed adjacent the sheet metal shell or mounted on it as a baffle or guard plate. A special rain shield may also be associated with the sheet metal shell and if both a wind deflector and a rain shield are provided they may be constructed as a shed-like modification of the sheet metal shell. The wind deflector and/or the rain shield may be made from thin metal or plastics plates. They may alternatively be constituted by organic or inorganic coatings. In contrast to known insulating means, the protective measures of the present invention do not aim to avoid stress corrosion by the temperature of the heat metal shell exceeding the condensation point. It is also possible to dispose the hot blast stove initially at geographical locations where the climatic effects such as the wind, temperature and rain, or changes therein are relatively slight. The accompanying drawings illustrate the problem with which the present invention is concerned in more detail. Figure 1 represents a vectorial addition of the wind strength and direction to be expected at the site of a hot blast stove, reference numerals 1 to 7 indicating winds blowing from the North-West, West, South-West, South, East, North-East and North respectively whilst reference numeral 8 represents the vectorial addition or resultant of these. Figure 2 is a schematic representation of a blast furnace installation including a blast furnace 12 to which two hot blast stoves are connected, each of which comprises a heat exchange. 10 and a combustion shaft 11 within a respective sheet metal shell. Figure 3 is a graphical representation of the crack frequency or concentration, shown on the Y axis, at various points on the shell of one of the combustion shafts. The positions of these points on the shell are indicated angularly with reference to the scale shown adjacent Figure 2 with respect to the resultant or primary wind direction illustrated in Figure 1. Figure 3 can thus be considered as showing the crack concentration on a development of the sheet metal shell of a combustion shaft. CLAIMS

7. A hot blast stove as claimed in any one of the preceding claims which is arranged at a geographical location where the wind, temperature or rain effects are comparatively low.

8. A hot blast stove as claimed in any one of Claims 1 to 7 which is provided with a water spraying arrangement which is constructed and arranged that there is a substantially constant temperature field around the sheet metal casing.