BURNER AND PROCESS FOR THE PARTIAL OXIDATION OF LIQUID, CARBONACEOUS FUEL

BRULEUR ET PROCEDE POUR L'OXYDATION PARTIELLE DE COMBUSTIBLE LIQUIDE, CONTENANT DU CARBONE

English Abstract

The invention relates to a burner for partially oxidizing liquid, carbon-containing fuel, said fuel having water vapor and an oxygen-containing gas, and to the method in which said burner is used, wherein the parts of the outlet opening of the burner directed toward the combustion chamber are completely or partially provided with a coating or with a diffusion layer for protecting against thermal loading and/or corrosion.

French Abstract

L'invention concerne un brûleur pour l'oxydation partielle de combustible liquide, contenant du carbone, par de la vapeur d'eau et un gaz contenant de l'oxygène, ainsi que le procédé selon lequel ce brûleur est utilisé, les pièces orientées vers la chambre de combustion de l'orifice de sortie du brûleur étant pourvues totalement ou partiellement d'un revêtement ou d'une couche de diffusion pour la protection contre une sollicitation thermique et/ou la corrosion.

Claims

8
Claims:
1. A burner for the partial oxidation of liquid, carbonaceous fuel with
steam
and an oxygen-containing gas, whose outlet orifice is directed into a
combustion chamber, wherein parts of the outlet orifice directed towards
the combustion chamber are wholly or partly provided with a coating which
consists of an adhesive layer and a heat insulation layer, which each are
applied by a thermal spraying method, and wherein the adhesive layer
consists of the metal mixture MCrAIY, M representing at least one of the
elements Ni, Co, Pt or Pd).
2. The burner according to claim 1, wherein the thermal spraying method is
plasma spraying.
3. The burner according to claim 1 or 2, wherein the heat insulation layer
consists of an oxidic spraying material.
4. The burner according to any one of claims 1 to 3, wherein the heat
insulation layer is ZrO2.
5. A process for the partial oxidation of liquid, carbonaceous fuel with
steam
and an oxygen-containing gas, wherein at least one burner according to at
least one of claims 1 to 4 is used.

Description

, CA 02794240 2012-09-24
,
Lurgi GmbH 14.04.2011 / Wro
/ mv
Lurgiallee 5
60439 Frankfurt
Lurgi File Number: L08P31 DE
Burner and Process for the Partial Oxidation of Liquid,
Carbonaceous Fuel
Field of the Invention
This invention relates to a burner for the partial oxidation of liquid,
carbonaceous fuel with
steam and an oxygen-containing gas, and to the process for producing synthesis
gas by
partial oxidation of said fuels, in which the burner according to the
invention is used.
Prior art
A known process for the partial oxidation of liquid, carbonaceous feedstocks
for the
production of synthesis gas for example is the Lurgi process as described in
Ullmann's
Encyclopedia of Industrial Chemistry, 6th Edition, Volume 15, Chapt. 3.2.2.
In such processes, the hydrocarbonaceous feedstock stream, e.g. heavy oil,
together with
the oxygen-containing oxidizing agent, e.g. air enriched with oxygen, and
possibly a
moderator (mostly steam or carbon dioxide) is converted into a synthesis gas
chiefly
consisting of carbon monoxide and hydrogen in a reactor space (combustion
chamber) at
temperatures of 1200 to 1500 C and high pressures, between 30 and 75 bar.
The reactor is equipped with one or more burners which in general are
installed at the
head of the reactor such that their flame is vertically guided into the
reactor from top to
bottom, so that only the lower end of the burner throat protrudes into the
combustion
chamber and is exposed to the high temperatures and the corrosive atmosphere
of the
combustion chamber. Such burner is described in DE 198 60 479 C1 and in DE 199
31
373A1.

CA 02794240 2012-09-24
- 2 -
The high temperatures and corrosive gases obtained in these processes for
producing
synthesis gas limit the durability of the burners. Therefore, at least the
components of the
burners subjected to high loads are fabricated from so-called superalloys.
These are high
temperature resistant alloys, such as high-carbon nickel-chromium-iron alloys.
Fundamental statements on superalloys can be found in Rompps Chemie-Lexikon,
8th
edition, Franckh'sche Verlagshandlung, Stuttgart.
Beside the selection of particularly robust construction materials numerous
constructive
methods have been developed to extend the service life of the burners.
In EP 0 545 281 B1 it is proposed to line the end face of the burner throat
with a layer
composed of individual ceramic platelets arranged one beside the other.
In EP 1 284 234 A2 it is proposed to divide the inner burner tube into two
halves
releasably connected with each other, wherein only the lower half facing the
end face of
the burner is made of a particularly high temperature resistant and high-
melting metal
alloy. The end face of the outer burner tube is equipped with a space for the
passage of a
cooling medium and in addition the burner throat protruding into the reactor
is surrounded
with cooling coils.
DE 601 20 674 T2 proposes the installation of an annular heat shield on the
end face of
the burner throat, which is made of a material with a high melting point.
What is disadvantageous in the previously proposed solutions for extending the
service
life of the burner is the fact that they intervene in the construction of the
burner throat, so
that in the construction a compromise must be found between the actual
function of the
burner and the measures for protecting the same against corrosion.
Description of the Invention
Therefore, it has been the object to find a solution for extending the service
life of the
burner, which rather does not intervene in the construction of the burner and
can be
carried out economically.

CA 02794240 2014-09-11
3
That object is achieved with a burner for the partial oxidation of liquid,
carbonaceous
fuel with steam and an oxygen-containing gas, whose outlet orifice is directed
into a
combustion chamber, wherein parts of the outlet orifice directed towards the
combustion chamber are wholly or partly provided with a coating which consists
of an
adhesive layer and a heat insulation layer, which each are applied by a
thermal
spraying method, and wherein the adhesive layer consists of the metal mixture
MCrAIY, M representing at least one of the elements Ni, Co, Pt or Pd). Further
advantageous aspects of the invention can be taken from the sub-claims. This
invention also
relates to a process for the partial oxidation of liquid, carbonaceous fuel
with steam and an
oxygen-containing gas, in which the burner according to the invention is used.
This object is solved in that the parts of the outlet orifice directed towards
the combustion
chamber are wholly or partly provided with a coating or with a diffusion layer
for protection
against thermal load and/or corrosion.
This inventive solution of the object was induced by the proven practice in
the construction of
hot gas turbines to provide the parts exposed to high temperatures and
corrosive gases with
a protective ceramic layer, as is reported e.g. in DE 35 43 802 A1.
Preferred Aspects of the Invention
In accordance with a preferred aspect of the invention the burner according to
the invention
is provided with a coating of an adhesive layer and a heat insulation layer,
which each are
applied by a thermal spraying method, such as plasma spraying, wherein the
adhesive layer
consists of the metal mixture MCrAlY (M represents at least one of the
elements Ni, Co, Pt or
Pd) and wherein the heat insulation layer preferably consists of an oxidic
spraying material,
in particular of Zr02. This combination of materials was found to be
particularly effective with
regard to the extension of the service life of the burner.
In a further aspect of the invention it is provided that by alitizing,
chromizing or siliconizing
merely a diffusion layer is produced in the surface of the workpiece. The
separate heat
insulation layer is omitted, which contributes to the constructive simplicity
of the burner
according to the invention.

CA 02794240 2014-09-11
4
In accordance with a particularly preferred aspect of the invention the burner
designed
according to the invention is wholly or partly provided with a combination of
a coating for
protection against thermal load and a diffusion layer on its parts of the
outlet orifice directed
towards the combustion chamber. In this way, a particularly marked extension
of the service
life and the related operating cost advantages are achieved.
This invention also relates to a process for the partial oxidation of liquid,
carbonaceous fuel
with steam and an oxygen-containing gas, which is characterized in that at
least one burner
as described above is used. Details of the procedure and constructive details
of the burner
are known to the skilled person and described already for example in the
documents
DE 19931373A1, DE 19860479 C1, DE 10152686A1 and DE 10156980A1.
In the drawings:
Fig. 1 shows the arrangement of the burner according to the invention in
the
combustion chamber,
Fig. 2 shows the position and the layered structure of the protective layer
according to a
first preferred aspect of the invention,
Fig. 3 shows the position and the layered structure of the protective layer
according to a
second preferred aspect of the invention,
Fig. 1 shows how the throat (1) of the burner extends through the reactor wall
(3) into the
combustion chamber (4) of the reactor with the lower end of the outer burner
tube (2). In this
example, the throat of the burner (1) is constructed of two concentric tubes.
The inner tube
(5) conveys a mixture (6) of carbonaceous fuel and steam, the outer tube (2)
conveys the
oxygen (7) necessary for the combustion and/or partial oxidation, which is
possibly mixed
with steam or carbon dioxide. Fig. 1 shows the inner (5) and outer (2) tube
ends of the burner
throat by way of example as straight tube pieces. Other tube shapes are,
however, also
possible, such as tubes conically tapering towards the tube end or widening
tubes. It is also
possible that the outer tube (2) is provided with a cooling chamber (9) in
which a coolant is
contained. In this example shown in Fig. 1 the end face of the outer tube (2)
directed into the
combustion chamber (4) is provided with a protective layer (8) which according
to the

CA 02794240 2014-09-11
invention can be a coating or a diffusion layer. Of course, the lower end face
of the inner tube
(5) can also be provided with such protective layer, which is not shown in
Fig. 1.
As indicated in Fig. 1, the protective layer (8) can not only cover the end
face, but also the
surfaces in the inner or outer region of the tube or tubes of the burner
throat.
Fig. 2 shows the layered structure of the protective layer ((8) in Fig. 1)
according to claim 2.
In an aspect of the invention, an adhesive layer (11) and a heat insulation
layer (13) each are
applied onto the workpiece (10) by a thermal spraying method, such as plasma
spraying,
wherein the adhesive layer (11) consists of the metal mixture MCrAlY (M
represents at least
one of the elements Ni, Co, Pt or Pd) and wherein the heat insulation layer
(13) preferably
consists of an oxidic spraying material, in particular of Zr02. The surface
(12) of this adhesive
layer (11) additionally is enriched with aluminum and silicon atoms in its
surface by a
diffusion treatment, by so-called alitizing/siliconizing.
Thermal coating methods, such as plasma spraying, useful for the solution of
the object are
described in Ullmann's Encyclopedia of Industrial Chemistry, 6th Edition,
Volume 21,
Chapt. 5.
The fact that the durability of the protective layer is improved by priming by
means of an
adhesive layer of this type is known to the skilled person for example from US
4,321,310. In
the development of the present invention MCrAlY spraying material with the
trade name
SICOAT 2464 has been used successfully.
Fig. 3 shows the structure of the protective layer ((8) in Fig. 1) according
to one embodiment.
A variant of the invention consists in that a coating of the workpiece (10')
is omitted and
instead the surface to be protected merely is subjected to a diffusion
treatment, wherein
aluminum and/or silicon and/or chromium atoms diffuse into the surface (12').
These
processes are known to the skilled person as alitizing, siliconizing ____

= CA 02794240 2012-09-24
- 6 -
and chromizing. The fundamentals of the used diffusion treatment are described
in
IROmpps Chemie-Lexikon, 8th edition, Franckh'sche Verlagshandlung, Stuttgart.
Industrial Applicability
The present invention provides a burner which is characterized by a high
resistance to
thermal and corrosive loads.

. CA 02794240 2012-09-24
- 7 -
List of Reference Numerals
(1) burner throat
(2) outer burner tube
(3) reactor wall
(4) combustion chamber
(5) inner burner
(6) mixture of carbonaceous fuel and steam
(7) oxygen
(8) protective layer
(9) cooling chamber
(10), (10') workpiece
(11) adhesive layer
(12), (12') surface of the adhesive layer
(13) heat insulation layer

Representative Drawing