METHOD AND ARRANGEMENT FOR HEATING EXTENDED STEEL PRODUCTS

PROCEDE ET ENSEMBLE PERMETTANT DE CHAUFFER DES PRODUITS EN ACIER ALLONGES

English Abstract

A method for heating extended steel products, such as pipes, tape or wire
products or rods following working such as rolling or extrusion to a heat
treatment temperature, normally to approximately 50 to 900 degrees Celsius.
The invention is characterised in that the heating is caused to take place
through the product (9) being caused to be fed through a burner (1) that has a
central through channel (2) into which the product is fed, in that fuel and
oxidant are caused to be supplied through channels (4, 5) that exist outside
of the said central channel (2), in that fuel and oxidant are caused to be
supplied at such a rate that the combustion is caused to take place in front
of the outlet opening (13) of the burner head (12) of the burner (1). The
invention also relates to an arrangement.

French Abstract

La présente invention concerne un procédé permettant de chauffer des produits en acier allongés, tels que des tuyaux, des produits du type bande ou fil métallique ou des tiges suite à un traitement du type laminage ou extrusion, jusqu'à une température de traitement thermique, normalement jusqu'à environ 50 à 900 °C. L'invention se caractérise en ce que le chauffage est effectué de manière à concerner l'ensemble du produit (9) destiné à être acheminé par l'intermédiaire d'un brûleur (1) doté d'un canal traversant central (2) à l'intérieur duquel le produit est acheminé, en ce que le carburant et l'oxydant sont acheminés par l'intermédiaire de canaux (4, 5) qui se trouvent à l'extérieur dudit canal central (2), en ce que le carburant et l'oxydant sont acheminés à une vitesse telle que la combustion se déroule face à l'ouverture de sortie (13) de la tête (12) du brûleur (1). Cette invention se rapporte également à un ensemble associé.

Claims

7
Claims
1. A method for heating extended steel products, such as
pipes, tape or wire products or rods following working such
as rolling or extrusion to a heat treatment temperature,
normally to approximately 50 to 900 degrees Celsius, c h a r-
a c t e r i s e d in that the heating is caused to take place
through the product (9) being caused to be fed through a
burner (1) that has a central through channel (2) into which
the product is fed, in that fuel and oxidant are caused to be
supplied through channels (4, 5) that exist outside of the
said central channel (2), in that fuel and oxidant are caused
to be supplied at such a rate that the combustion is caused
to take place in front of the outlet opening (13) of the
burner head (12) of the burner (1).
2 . A method according to claim 1, c h a r a c t e r i s e d in
that the product (9) is caused to be fed through the burner
in a direction that is opposite to the direction of flow of
the exhaust gases of the burner.
3 . A method according to claim 1 or 2 , characterised
i n that oxidant and fuel are caused to be fed out from the
outlet opening (13) of the burner in a symmetrical manner
with respect to the product (9).
4 . A method according to claim 3, characterised in
that oxidant and fuel are caused to be fed out from the out-
let opening (13) of the burner evenly distributed along the
periphery of the product (9).
5. A method according to claim 1, 2, 3 or 4, character-
ised in that fuel and oxidant are supplied at an angle

8
that lies between 1 and 90 degrees to the longitudinal axis
of the product (9).
6. A method according to claim 1, 2, 3, 4, or 5, charac-
terised in that the oxidant is caused to contain at
least 85% oxygen by volume.
7 . A method according to claim 1 , 2 , 3, 4 , 5 or 6, char-
acterised in that the flame is caused to be formed
within a flame tube (14) that extends out from the outlet
opening (13) of the burner (1) and is concentric with the
transport pathway of the product (9).
8. An arrangement for heating extended steel products, such
as pipes, tape or wire products or rods following working
such as rolling or extrusion to a heat treatment temperature,
normally to approximately 50 to 900 degrees Celsius, char -
acterised by a burner (1) that has a central through
channel (2) arranged for the feed of the product (9) through
the burner (1), by channels (4, 5) in the burner (1) for the
supply of fuel and oxidant, which channels (4, 5) are located
outside of the said central channel, by the arrangement of
the said channels (4, 5) for the supply of fuel and oxidant
such that combustion takes place in front of the outlet open-
ing (13) of the burner head (12) of the burner.
9. An arrangement according to claim 8, characterised
i n that the product (9) is arranged to be fed through the
burner (1) in a direction that is opposite to the direction
of flow of the exhaust gases of the burner (1).
10. The arrangement according to claim- 8 or 9, charac-
terised in that the outlet opening (13 ) of the burner

9
is arranged to supply fuel and oxidant at an angle that lies
between 1 and 90 degrees to the longitudinal axis of the
product (9).

Description

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Method and arrangement for heating extended steel products.
The present invention relates to a method and an arrangement
for heating extended steel products.
During working of steel products, the mechanical, metal-
lographic and surface chemical properties of the material
change. It may be necessary to change these properties before
further working and/or use. Heat treatment is one method of
changing the properties of the material. Heat treatment in-
volves the heating of the material to a certain temperature,
followed by its subsequent cooling.
The rate of heating depends on three factors, namely the
supply of heat to the surface of the material, transfer of
heat from the boundary layer to the surface of the material,
and the conduction of heat in the material. The conduction of
heat in the material is a material constant and for this
reason it cannot be influenced, whereby the supply of heat
and the transfer of heat in the boundary layer remain as
processes to influence.
One problem during the heating of extended steel products is
that the supply of energy should be even over the material
surface of the product.
Another problem consists of the material surface of a product
that is to be heated often having chemicals, such as roller
oils, lubricating soap grease, rust protection oils, polymers
and organic and/or inorganic particles. Such contaminants may
give undesirable effects on the surface during heating or
heat treatment, such as deposits on or in the heat treatment

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equipment, visual surface defects on the material and/or an
influence on the surface properties of the ready material.
The present invention solves these problems.
The present invention thus relates to a method for heating
extended steel products, such as pipes, tape or wire products
or rods following working such as rolling or extrusion to a
heat treatment temperature, normally to approximately 50 to
900 degrees Celsius, and it is characterised in that the
heating is caused to take place through the product being
caused to be fed through a burner that has a central through
channel into which the product is fed, in that fuel and oxi-
dant are caused to be supplied through channels that exist
15. outside of the said central channel, in that fuel and oxidant
are caused to be supplied at such a rate that the combustion
is caused to take place in front of the outlet opening of the
burner head of the burner.
The invention also relates to an arrangement of the nature
and having the principal features that are specified in
claim 8.
The invention.is described in more detail below, partly in
association with an embodiment of the invention shown in the
attached drawing whe.re
- Figure 1shows a section through a burner according to
the present invention, and
The present invention concerns the heating of extended steel
products, such as pipes, tape or wire products or rods fol-
lowing working such as rolling or extrusion to a heat treat
RECTIFIED SHEET (RULE 91)

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ment temperature, normally to approximately 50 to 900 degrees
Celsius.
According to the invention, the heating is caused to take
place through the product being caused to be fed through a
burner. The burner has a central through channel into which
the product is fed. Fuel and oxidant are caused to be sup-
plied through existing channels located outside of the said
central channel. According to the invention, furthermore,
fo fuel and oxidant are caused to be fed forwards at such a rate
that combustion is caused to take place in front of the out-
let opening of the burner head of the burner.
Figure 1 shows an arrangement in the form of a burner 1 for
the heating of extended steel products.
The burner 1 has a central through channel 2 arranged such
that the product is fed through the burner 1. The channel 2
comprises a tube 3. Furthermore, channels 4, 5 are present in
the burner for the supply of fuel 6 and oxidant 7, located
outside of the said central channel 2. The said channels for
the supply of fuel and oxidant are, according to the inven-
tion, arranged such that combustion takes place in front of
the outlet opening of the burner head of the burner.
The material is caused according to one preferred embodiment
to be fed through the burner in a direction that is opposite
to the flow of the exhaust gases.
The material 9 is fed through the burner 1 in the direction
of the arrow 10, while the exhaust gases flow in the direc-
tion of the arrow 11. The combustion of the fuel thus takes

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place outside of the opening 13 of the head 12 of the burner
1.
It is preferred that fuel and oxidant are caused to be sup-
plied at an angle of between 1 and 90 degrees to the longitu-
dinal axis of the product.
According to one preferred embodiment, the flame is caused to
be formed inside of a flame tube 14 that extends out from the
outlet opening 13 of the burner and is concentric with the
transport pathway of the product.
By passing the material through the burner, it is ensured
that the energy supplied is evenly distributed along the
periphery of the extended steel surface. There is a large
heating intensity or heating power at the first point of
contact, and this decreases away from the opening of the
burner in a direction that is opposite to the motion of the
material. The power of the pre-heating before the direct
impingement of the flame can be varied by adapting the length
of the flame tube. It is the length of the flame tunnel that
is varied. The combustion process can be made "flameless" by
the recirculation of exhaust gases that takes place in the
flame tunnel.
According to another preferred embodiment, oxidant and fuel
are caused to be fed out from the outlet opening 13 of the
burner in a symmetrical manner with respect to the product.
Thus it is preferred that oxidant and fuel are caused to be
fed out from the outlet opening of the burner evenly distrib-
uted along the periphery of the product.

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It is also preferred that the oxidant is caused to contain at
least 85% oxygen by volume.
The heating time for the material in the furnace is consid-
5 erably shortened through the higher transfer of heat, which
ensures that the rate of feed of the material through the
furnace can be considerably increased for a given furnace.
Furthermore, at least one of the combustion and the mechani-
cal blowing away of deposits and oil residues, etc. is
achieved by the direction of feed of the material being in a
direction that is opposite to the flow of the exhaust gases.
The surface will in this way become free of combustion prod-
ucts and other contaminants before further treatment, such
as, for example, heat treatment, working, removal of oxide,
etc.
In cross-section through a burner according to the invention,
it is divided into two halves along its longitudinal axis.
One half can be displaced relative to the other half by means
of a force-producing means. The construction of the burner in
a divided form ensures the advantage that the extended steel
product does not need to be threaded through the burner dur-
ing the start-up procedure.
It is thus apparent that the present invention solves the
, problems that have been described in the introductory part.
RECTIFIED SHEET (RULE 91)

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A number of embodiments have been described above. It is,
however, clear that the detailed design of the burner can be
varied and optimised for a particular steel product.
Thus the present invention is not to be considered as being
limited to the embodiments specified above, since it can be
varied within the scope of the attached claims.

Representative Drawing