Title of Invention

SYNTHESIS FURNACE

Abstract Synthesis furnace (1) with a furnace chamber (3) surrounded by a furnace wall (2) all around, in which several burners (5) are arranged mainly in one plane with the burner outlet direction pointed downwards, whereby at least the outer burners (5) arranged in the region of the furnace wall (2) have a burner outlet direction (R), which is inclined from the centre of the furnace moving away towards the vertical and in which several reaction pipes (4) are arranged mainly perpendicular and parallel to one another, that are heated from outside by the firing burners (5), characterized in that the inclination of the burner outlet direction (R) of the individual burners (5) is different.
Full Text "Synthesis Furnace"
The invention relates to a synthesis furnace with a furnace chamber surrounded

by a wall
all around, in which there are several burners mainly arranged on one level,

with the
burner orifice directed downwards and several reaction pipes arranged mostly
perpendicular and parallel to one another, whereby the reaction pipes are

heated from
outside by the firing burners.
Such synthesis furnaces, e.g. for producing ammonia, methanol or hydrogen, are
sufficiently well known and are designed for use in big technology often as

generic top-
fired box furnaces with vertically standing reaction tubes or slotted tubes.

These reaction
tubes are arranged in series and are charged through from above to below with

process
gas. This process gas is thereby subjected to a so-called fission process. The

process gas
is collected below either inside or outside the furnace in exit collectors. In

the lanes
between the pipe rows the pipes get heated by the burners arranged above in the

furnace
and firing vertically downwards; the flue gas generated by the burner flows

through the
furnace from top to bottom and is drawn away through the flue gas tunnel

arranged on the
floor (e.g. published in: "Ammonia: Principles and Industrial Practice/Max Appl

-
Weinheim; New York, Chichester; Brisbane; Singapore; Toronto; Wiley-VCH, 1999,
ISBN 3-527-29593-3, pages 80-89).
In such synthesis furnaces, particularly with a large number of pipe rows, a

very
un-uniform flow is observed, especially in the outer pipe rows mainly

influenced by re-
circulation. This re-circulation leads to low flue gas and process gas

temperatures in the
outer pipe rows as compared to the central rows. This low temperature in the

outer rows
has a disadvantageous effect on the fission process. Besides, it also leads to

flame
deflection in the outer burner rows, which hampers the entire heat transfer and

increases
the material load.
In order to avoid these known problems, already various solutions have been

suggested
(Flue Gas Flow Patterns in Top-fired Steam Reforming Furnaces, P.W. Farnell &

W. J.
Cotton, Synetix, Billingham, England, 44th Annual Safety in Ammonia Plants and
Related Facilities symposium, Seattle, Washington, paper no. 3e, September 27 -

30,
1999). On the one hand, it is suggested that the outer burners be operated with

higher air
discharge velocities, and on the other hand, that the process gas be

distributed in a
specific manner in different quantities to the reaction pipes. However, both

the solutions
have not proved to be satisfactory. It has also been suggested that the burner

distance to
the furnace wall be increased. However, this solution also does not solve the

above
mentioned problems.
It is therefore the task of this invention to improve the heat distribution and

the total heat
transfer in a simple design and technically easy to control manner.
This task is fulfilled in the case of a synthesis furnace of the type described

above, in that
at least the outer burners arranged in the region of the furnace wall have a

burner outlet
direction that is inclined starting from the centre of the furnace and moving

away from
the vertical.
It has been seen that by using this solution, as against the previously

described known
solutions, the flame deflection of the outer burner rows towards the centre of

the furnace
can be significantly reduced in a design-wise and control-technically simple

manner.
One obtains a mainly more uniform flow-off of the flue gases along the reaction

pipes,
the heat transfer gets improved and the increased material load of the reaction

pipes due
to "hot spots" in case of synthesis furnaces according to the state-of-the-art

technology,
gets significantly reduced, so that the life-span of the reaction pipes

increases
significantly.
In order to achieve a good heat distribution or flue gas flow, it is foreseen

that the
inclination of the burner outlet directions of the individual burners is

different. This
means that the burners, depending on the suction effect of adjacent burner

flames on the
respective own flame, are arranged at a corresponding angle of inclination

(opposed to
the suction effect of adjacent burners).
It is thereby foreseen that the inclination of the burner exit directions of

the burners,
starting from the centre of the furnace, increases outwards towards the furnace

walls.
Whereas the centrally arranged burners do not have any inclination, the

inclination of the
burner rows increases towards the outside to a maximum value.
It has also been proved to be particularly useful if the angle of inclination,

starting from
the centre, lies between 0 to 10°, preferably between 0 to 5°.
In order to realise the inclination of the burners, design-wise it can be

foreseen that the
burners with inclined burner exit direction are installed altogether inclined

and/or their
burner orifice is arranged in an inclined manner.
It is also foreseen that the inclination of the burner outlet direction is

adjustable, i.e.
during operation of the synthesis furnace these can be altered for adapting to

the
respective conditions/patterns.
For this, it is particularly foreseen that for setting the inclination a

control system is
foreseen, that takes into consideration the operation parameters of the

synthesis furnace.
The invention is described in details below on the basis of the drawing. The

following
are shown:
Fig. 1 A principle diagram of a synthesis furnace;
Fig.2a The temperature distribution in a synthesis furnace according the

state-of-the-art
technology;
Fig.2b The temperature distribution in a synthesis furnace as per the

invention;
Fig.3a Flow patterns in a synthesis furnace according to the state-of-the-art

technology;
Fig.3b Flow patterns in a synthesis furnace as per the invention; and
Fig.4 A diagram in which the heat flow density for the outermost pipe row over

the pipe
length for a synthesis furnace according to the state-of-the-art technology and

the
synthesis furnace as per the invention is shown.
A synthesis furnace is generally denoted in fig. 1 by the reference sign 1.

This synthesis
furnace is designed as box-type or square-type and has a furnace chamber 3

surrounded
by a furnace wall 2 all around.
Within this furnace chamber 3 several reaction pipes 4 are arranged, mainly

arranged
perpendicular and parallel to one another, through which process gas is

introduced from
above, which is not shown in more details. This process gas flows from top to

bottom
through the reaction pipes 4 and is collected in the lower region of the

furnace or outside
it in exit collectors that have not been shown.
In the region between the reaction pipes 4 or pipe rows formed by these,

several
burners 5 are arranged in the upper region of the chamber 3 mainly on one

level.
However, these burners 5 have a burner outlet direction pointing downwards; in

fig. 1,
for each burner 5 a vertical burner axis 6 has been drawn with dashed line.
Now it is important that at least the outer burners 5 arranged in the region of

the furnace
wall 2 have a burner outlet direction R, which is inclined moving away from the

centre of
the synthesis furnace 1 against the vertical. This angle of inclination is

denoted by a in
fig. 1 and defined opposite to the allied vertical burner axis 6. It is obvious

that, contrary
to the two dimensional depiction in fig. 1, this inclination can also stretch

or stretch
additionally, depending on the arrangement of the burners, towards the centre

of the
furnace chamber 3 in the plane stretched transverse to the shown drawing plane.

The
centre of the furnace chamber 3 is thereby situated in the region of the plane

supporting
the central reaction pipes 4m.
It is particularly advantageous, if not only the burner outlet directions R of

the outer
burners 5 are inclined, but also those of the central and inner burners,

whereby the
arrangement is made in such a way that the inclination increases starting from

the inner
burners towards the furnace wall 2; the inclination y of the inner burners is

clearly lesser
than the inclination P of the central burners and this again is lesser than the

inclination a
of the outer burners.
The angle of inclination a of the outer burners lies at approx. maximum 10°,

preferably
5°; the angle of inclination p and y are suitably selected lesser.
The inclination of the burners 5 can be realised in different ways; on the one

hand, it can
be foreseen that the burners are installed altogether inclined or only their

burner orifice or
burner nozzle is inclined.
It is particularly advantageous if the inclination of the burners 5 can be

adjusted,
especially also during operation; in this case a control system (not shown) can

be
foreseen for the synthesis furnace 1, which takes up an adjustment of the

inclinations
under consideration of the operation parameters of the synthesis furnace 1.
By means of this extended design of the burners 5, the flame deflection of the

outer
burner rows towards the centre gets significantly reduced; one obtains a

uniform or more
uniform flow-off of the flue gas along the reaction pipes, the heat transfer

gets improved
and the increased material load due to "hot spots" gets clearly reduced.
These advantages as compared to the state-of-the-art technology can be clearly

seen in
figures 2a and 2b on the one hand, and in 3a and 3b on the other hand.
Fig. 2a shows a very un-uniform temperature distribution in a traditional

synthesis
furnace without burner inclination. As against that, an extended design

according to the
invention can be identified in fig. 2b, in which the outer burners or their

burner outlet
direction is inclined by 5° and one can see a clearly more homogeneous

temperature
distribution.
One can see similar behaviour pattern also in the flow condition shown in

figures 3a and
3b. Fig. 3a shows the flow patterns for a traditional synthesis furnace without

burner
inclination and fig. 3b with burner inclination, that too for an inclination by

5° in the
outer burners. The undesirable dead zones (white empty surfaces) get

significantly
reduced in the design as per the invention.
In fig. 4 the heat flow density for the outermost pipe row is plotted over the

pipe length,
in dashed-line for a synthesis furnace according to the state-of-the-art

technology and in a
continuous line for a synthesis furnace as per the invention with outer burners

inclined by
5°. It can be clearly seen that the heat flow density over the pipe length is

much more
uniformly distributed in a synthesis furnace according to the invention.
WE CLAIM:
1. Synthesis furnace (1) with a furnace chamber (3) surrounded by a
furnace wall (2) all around, in which several burners (5) are arranged
mainly in one plane with the burner outlet direction pointed
downwards, whereby at least the outer burners (5) arranged in the
region of the furnace wall (2) have a burner outlet direction (R),
which is inclined from the centre of the furnace moving away towards
the vertical and in which several reaction pipes (4) are arranged
mainly perpendicular and parallel to one another, that are heated from
outside by the firing burners (5), characterized in that the inclination
of the burner outlet direction (R) of the individual burners (5) is
different.
2. Synthesis furnace as claimed in claim 1, wherein the inclination of the
burner outlet directions (R) of the burners (5), starting from the centre
of the furnace, increases outwards towards the furnace walls (2).
3. Synthesis furnace as claimed in claim 1 or one of the following
claims, wherein the angle of inclination, starting from the centre, lies
between 0 to 10°, preferably between 0 to 5°.
4. Synthesis furnace as claimed in claim 1 or one of the following
claims, wherein the burners (5) with inclined burner outlet direction
(R) are altogether installed inclined and/or their burner orifice is
arranged inclined.
5. Synthesis furnace as claimed in claim 4, wherein the inclination of the
burner outlet directions (R) is adjustable.
6. Synthesis furnace as claimed in claim 5, wherein for setting the
inclination a control system is foreseen that takes into account the
operating parameters of the synthesis furnace.


Synthesis furnace (1) with a furnace chamber (3) surrounded by a furnace
wall (2) all around, in which several burners (5) are arranged mainly in one
plane with the burner outlet direction pointed downwards, whereby at least
the outer burners (5) arranged in the region of the furnace wall (2) have a
burner outlet direction (R), which is inclined from the centre of the furnace
moving away towards the vertical and in which several reaction pipes (4) are
arranged mainly perpendicular and parallel to one another, that are heated
from outside by the firing burners (5), characterized in that the inclination of
the burner outlet direction (R) of the individual burners (5) is different.

Documents:


Patent Number 247515
Indian Patent Application Number 1547/KOLNP/2006
PG Journal Number 16/2011
Publication Date 22-Apr-2011
Grant Date 13-Apr-2011
Date of Filing 06-Jun-2006
Name of Patentee UHDE GMBH
Applicant Address FRIEDRICH-UHDE-STRASSE 15 44141 DORTMUND
Inventors:
# Inventor's Name Inventor's Address
1 GORVAL, EVGENL MARKISCHE STRASSE 96 44141 DORTMUND
PCT International Classification Number B01J8/06; C01B3/38
PCT International Application Number PCT/EP04/011442
PCT International Filing date 2004-10-13
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 103 57 064.0 2003-12-04 Germany