TITLE OF THE INVENTION
“BURNER AND METHOD FOR OPERATING A BURNER”
5 Description
The present invention relates to a burner for combustion of fluids as well as to a
method for operating a burner.
10 Prior art
A wide range of burner technologies exists, which can be used in high
temperature heating and melting processes such as aluminium melting or
remelting furnaces, steel reheating furnaces and glass melting furnaces. By means
15 of these burners, combustion of fluids is performed, particularly of a fuel like
natural gas, methane, propane, etc., and an oxidant. For example, air can be used
as oxidant, in so called air-fuel burners. Further, pure oxygen can be used as
oxidant, in so called oxy-fuel burners. It is also possible to use a combination of
air and oxygen as oxidant, in so called air-oxy-fuel burners.
20
Oxy-fuel burners can perform flameless or semi flameless combustion of the fuel
with high purity oxygen. In so called low temperature oxy-fuel burners (LTOF)
the combustion can occur under a diluted oxygen concentration by mixing furnace
gases into the combustion zone. So called low emission air-oxy-fuel burners
25 (LEAF) can be used for combustion with air, oxygen enriched air and pure
oxygen.
The addition of pure oxygen to the combustion process, i.e. in air-oxy-fuel burners
or oxy-fuel burners, can offer advantages resulting from the reduction in the
30 volume of the products of combustion and waste heat and the increase in flame
temperature and heat transfer and consequent production rates and process
efficiency. However, the addition of pure oxygen to the combustion process also
comes with some challenges in the control of NOx emissions. Reducing NOx
emissions is an important issue for most users of burners.
35
Disclosure of the invention
3
The present invention relates to a burner for combustion of fluids as well as a
method for operating a burner with the features of the independent claims.
Preferred embodiments and advantages of a method and a furnace according to
the invention are subject of the dependent claims and of the following description.
5
The burner comprises an inner or central fluid supply unit and an outer or
peripheral fluid supply unit. These inner and outer fluid supply units provide a
specific supply system for different fluids to be combusted. Particularly, the
burner is provided for combustion of a fuel, particularly natural gas or methane,
10 and at least one oxidant, particularly air and/or oxygen.
The inner fluid supply unit comprises a first inner fluid ejection element,
particularly a first pipe, particularly for ejecting a first fluid, a second inner fluid
ejection element, particularly a second pipe, particularly for ejecting a second
fluid, and a third inner fluid ejection element, particularly a third pipe, particularly
15 for ejecting a third fluid. The second inner fluid ejection element encompasses,
i.e. circumferentially surrounds at least an axial portion of the first inner fluid
ejection element. Particularly, the first and the second inner fluid ejection
elements are arranged coaxially and further particularly concentrically. The third
inner fluid ejection element encompasses, i.e. circumferentially surrounds at least
20 an axial portion of the second inner fluid ejection element. Particularly, the second
and the third inner fluid ejection elements are arranged coaxially and further
particularly concentrically. Particularly, the first, second and third inner fluid
ejection elements are arranged coaxially and concentrically.
25 The outer fluid supply unit comprises at least two outer fluid ejection elements
configured for ejecting a first and a second oxidant. The at least two outer fluid
ejection elements are arranged at a specific radial distance from the inner fluid
supply unit, particularly from a centre of the inner fluid supply unit, particularly
from a centre of the first inner fluid ejection element. The term "radial distance
30 from the inner fluid supply unit" is particularly to be understood as the radial
distance between the centre of the inner fluid supply unit, particularly the centre
of the first inner fluid ejection element, and the centre of the corresponding outer
fluid ejection element, particularly at an axial end of the corresponding outer fluid
ejection element and/or at an axial end of the inner fluid supply unit. For example,
35 the specific radial distance can be up to twice the radius of the outermost inner
fluid ejection element of the inner fluid supply unit.
4
In a preferred embodiment, the specific radial distance is larger than the sum of
the outermost inner fluid ejection element and the radius of the encompassing
fluid ejection element of the outer fluid ejection element such that there is a
spatial distance between the inner fluid supply unit and the outer fluid supply unit.
5 The inner fluid supply unit and the outer fluid supply unit do not directly abut
each other. The specific radial distance can be 1.1 to 1.9 times or 1.2 to 1.8 times
or 1.3 to 1.7 times, or 1.4 to 1.6 times of the radius of the outermost inner fluid
ejection element.

We Claim:
5 1. A burner (100) for combustion of fluids comprising an inner fluid supply unit
(110) with fluid ejection elements and an outer fluid supply unit (120),
 wherein the inner fluid supply unit (110) comprises
o a first inner fluid ejection element (111), particularly a first
pipe, and
10 o a second inner fluid ejection element (112), particularly a
second pipe, encompassing at least an axial portion of the first
inner fluid ejection element (111) and
o a third inner fluid ejection element (112), particularly a third
pipe, encompassing at least an axial portion of the second
15 inner fluid ejection element (112) and
 wherein the inner fluid supply unit is configured for ejecting a first
oxidant, a second oxidant and a fuel by means of the fluid ejection
elements of the inner fluid supply unit (110)
 wherein the outer fluid supply unit (120) comprises at least two outer
20 fluid ejection elements (121), arranged at a specific radial distance
from the inner fluid supply unit (110), particularly from a centre of the
inner fluid supply unit (110), particularly from a centre of the first
inner fluid ejection element (111),
 wherein each individual outer fluid ejection element (121) is
25 configured for ejecting the first oxidant and the second oxidant by
means of a central fluid ejection element (122), particularly a central
pipe, and an encompassing fluid ejection element (123), particularly
an encompassing pipe, encompassing at least an axial portion of the
central fluid ejection element (122).
30
2. The burner according to claim 1 configured for controlling at least one ratio
between amounts of the ejected first oxidant and/or the ejected second
oxidant and/or the ejected fuel such that at least one process parameter is
optimised.
35
3. The burner according to claim 2 configured for
22
controlling a first ratio between an amount of the first oxidant and an amount
of the second oxidant ejected by means of both the inner fluid supply unit
(110) and the outer fluid supply unit (120);
controlling a second ratio between an amount of the first oxidant and/or the
5 second oxidant ejected by means of the inner fluid supply unit (110) and an
amount of the first oxidant and/or the second oxidant ejected by means of the
outer fluid supply unit (120); and
controlling the first ratio and the second ratio such that the at least one
process parameter is optimised.
10
4. The burner according to any one of the preceding claims, wherein the outer
fluid supply unit (120) comprises at least two outer fluid ejection elements
(121) arranged circumferentially around the inner fluid supply unit (110),
particularly such that the at least two outer fluid ejection elements (121) have
15 the same radial distance from the inner fluid supply unit (110), particularly
from the centre of the inner fluid supply unit (110).
5. The burner according to any one of the preceding claims, wherein at least one
pressure reducing element (102, 103) is attached to an inner wall and/or outer
20 wall of at least one of the fluid ejection elements of the inner fluid supply unit
(110).
6. The burner according to claim 5, wherein at least one pressure reducing
element (102, 103) is provided for an individual fluid ejection element (111,
25 113) of the inner fluid supply unit (110), wherein a fluid, which is to be
ejected by means of this individual fluid ejection element (111, 113), is
further to be ejected by means of at least one outer fluid ejection element
(121, 122) of the outer fluid supply unit (120).
30 7. A method for operating a burner (100) according to any one of the preceding
claims, comprising the steps of:
ejecting a first oxidant, a second oxidant and a fuel by means of individual
fluid ejection elements of the inner fluid supply unit (110) and the outer fluid
supply unit (120); and
35 controlling at least one ratio between amounts of the ejected first oxidant
and/or the ejected second oxidant and/or the ejected fuel such that at least one
process parameter is optimised.
23
8. The method according to claim 7, comprising the steps of:
controlling a first ratio between an amount of the first oxidant and the second
oxidant ejected by means of both the inner fluid supply unit (110) and the
5 outer fluid supply unit (120);
controlling a second ratio between an amount of the first oxidant and/or the
second oxidant ejected by means of the inner fluid supply unit (110) and an
amount of the first oxidant and/or the second oxidant ejected by means of the
outer fluid supply unit (120); and
10 controlling the first ratio and the second ratio such that the at least one
process parameter is optimised.