Note: Descriptions are shown in the official language in which they were submitted.
W O 96!03345 PCT/EP95/02877
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y A PROCESS FOR THE MANUFACTURE OF SYNTHESIS GAS
BY PARTIAL OXIDATION OF A GASEOUS HYDROCARBON-CONTAINING
FUEL USING A MULTI-ORIFICE (CO-ANNULAR) BURNER
The invention relates to a process for the manufacture of
synthesis gas by partial oxidation of a gaseous hydrocarbon-
containing fuel using a multi-orifice (co-annular) burner.
In particular, the invention relates to a process for partial
oxidation of a gaseous hydrocarbon-containing fuel wherein an
oxygen-containing gas, which is applied as an oxidiser, and a
gaseous hydrocarbon-containing fuel are supplied to a gasification
zone through a multi-orifice (co-annular) burner comprising a
concentric arrangement of n passages or channels coaxial with the
longitudinal axis of said burner, wherein n is an integer _> 2, and
wherein autothermically a gaseous stream containing synthesis gas is
produced under appropriate conditions.
The oxygen-containing gas, which is applied as an oxidiser, is
usually air or (pure) oxygen or steam or.a mixture thereof. In order
to control the temperature in the gasification zone a moderator gas
(for example steam, water or carbon dioxide or a-combination
thereof) can be supplied to said zone.
Those skilled in the art will know the conditions of applying
oxidiser and moderator.
Synthesis gas is a gas comprising carbon monoxide and hydrogen,
and it is used, for example, as a clean medium-calorific value fuel
gas or as a feedstock for the synthesis of methanol, ammonia or
hydrocarbons, which latter synthesis yields gaseous hydrocarbons and
liquid hydrocarbons such as gasoline, middle distillates, lub oils
and waxes.
In the specification and in the claims the term gaseous
hydrocarbon-containing fuel will be used to refer to hydrocarbon-
containing fuel that is gaseous at gasifier feed pressure and
temperature.
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According to an established process, synthesis gas is produced
by partially oxidising in a reactor vessel a gaseous fuel such as
gaseous hydrocarbon, in particular petroleum gas or natural gas, at
a temperature in the range of from 1000 °C to 1800 °C and at a
pressure in the range of from 0.1 MPa to 6 MPa abs. With the use of
an oxygen containing gas.
Synthesis gas will often be produced near or at a crude oil
refinery because the produced synthesis gas can directly be applied
as a feedstock for the production of middle distillates, ammonia,
hydrogen, methanol or as a fuel gas, for example, for heating the
furnaces of the refinery or more efficiently for the firing of gas
turbines to produce electricity and heat.
In co-annular (multi-orifice)- gas burners it has appeared that
the burner lifetime is restricted by phenomena of pre-ignition or
flame-flashback. Because of such phenomena the temperature of the
burnez-internals becomes too high and serious burner damage will
occur. Further, there are problems with corrosion of the gas burner
tips.
It is an object of-the..invention.to-provide a process for
partial oxidation of a gaseous hydrocarbon-containing fuel wherein a
good and rapid mixing or contacting of oxygen-containing gas
(oxidiser), fuel and, optionally, moderator gas in the gasification
zone is achieved beyond the exit of the burner and wherein burner-
damage by corrosion, pre-ignition or flame-flash-back is suppressed.
The invention solves the above burner damage problem in that in
the process of the invention the oxygen-containing gas applied as
oxidiser and the gaseous hydrocarbon-containing fuel are supplied to
the gasification zone through specific passages at specific
velocities.
The invention therefore provides a process for the manufacture
of synthesis gas by reacting oxygen-containing gas, applied as
oxidiser, and gaseous hydrocarbon-containing fuel in a reaction zone
of a substantially non-catalytic gas genera~ot comprising the steps
of injecting the said fuel and the said oxidiser into the reaction
zone through a multi-orifice ico-annular) burner comprising an
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arrangement of n separate passages or channels coaxial with the
longitudinal axis of said burner, wherein n is an integer _> 2 (2, 3,
4, 5 ...), wherein the (n-1)th passage is the inner passage with
respect to the nth passage, measured from the longitudinal axis of
the said burner, and wherein the said gaseous hydrocarbon-containing
fuel (optionally with a moderator gas) is passed through one or more
of the passages, but at least through the nth passage, whereby at
least one passage remains; the said oxidiser (optionally with a
moderator gas) is passed through one or more of the remaining
passages, but at least through the (n-1)th passage, and in such a
manner that in any two adjacent passages in Which oxidiser is passed
through the one passage, and gaseous hydrocarbon-containing fuel is
passed through the other passage, the said oxidiser has a higher
velocity than said hydrocarbon-containing fuel, and provided
that when n is 4, then all four passages are used.
In this manner the oxygen-containing gas (oxidiser) entrains
the gaseous hydrocarbon-containing fuel after which the partial
oxidation takes place in the gasification zone, and the burner-
internal blades that form the internal separation wall between the
oxygen-containing gas (oxidiser) and the hydrocarbon-containing gas
and which have a finite thickness, are cooled by the oxygen-
containing gas (oxidiser) and the hydrocarbon-containing gas (in
particular by connective cooling) to lower the flame temperature
just behind the tips.
Behind the tip of the blade there is unavoidably at least a
recirculation area in which both gaseous fuel and oxygen-containing
gas, applied as oxidiser, are present.
If the hydrocarbon-containing gas would have the highest
velocity, there will be oxygen-rich conditions at the burner-
internal-tip by means of "entrainment" which will lead to high flame
temperatures, high tip temperatures and serious loss of burner
material.
If the oxygen-containing gas, applied as oxidiser, has the
highest velocity, in the recirculation area there will be mainly
oxygen-depleted conditions, which will lead to lower flame
temperature. Thus, serious burner damage will not occur, which leads
VJO 96103345 PCTIEP95/02877
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to a long burner-lifetime.
Advantageously, for n 2 3, at least part (e.g. 20$) of the
gaseous hydrocarbon-containing fuel is passed through the said nth
passage and the remainder of the gaseous hydrocarbon-containing fuel
is passed through one or more of the remaining passages. The (
velocity of the oxygen-containing gas, applied as oxidiser, is
advantageously 20-150 m/s.
The velocity of the gaseous hydrocarbon-containing fuel is
advantageously 0.2-0.8 times the velocity of the oxygen-containing
gas, applied as oxidiser, in any two adjacent passages in which
oxidiser is passed through the one passage, and gaseous hydrocarbon-
containing fuel is-passed through the other passage.
In an advantageous embodiment pf the invention the respective
velocities are measured or calculated at the outlet of-the said
respective channels into the gasification zone. The velocity
measurement or calculation can be carried out by those skilled in
the art in any way suitable for the purpose and will therefore not
be described in detail. -
In another-advantageous embodiment of the invention-the
moderator gas is steam and/or water and/or carbon dioxide and the
oxidiser contains at least 90$ pure 02. In-still anothei
advantageous embodiment of the invention the gasification process is
carried out at a pressure of-.0_1-12 MPa abs.
Multi-orifice burners comprising arrangements of annular ,
concentric channels for supplying oxygen-containing gas (oxidiser),
fuel and moderator gas to a gasification zone are known as such
(vide e.9. EP-A-0,545,281 and DE-OS-2,935,754) and the mechanical
structures thereof--will therefore not be described in detail.-
Usually such burners comprise a number of slits at the burner
outlet and hollow-wall members with internal cooling fluid (e. g.
water) passages. The passages may or may not be converging at the
burner outlet. Instead of comprising internal cooling fluid
passages, the burner may be provided with a suitable ceramic or
refractory lining applied onto or suspended by a means closely
adjacent to the outer surface of the burner (front) wall for
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resisting the heat load during operation or heat-up/shut down
situations of the burner.
y No fuel passage is reserved for a fuel other than gaseous
hydrocarbon-containing fuel.
The invention will now be described in moze detail by reference
to the following examples.
A number of examples are given in the Table. In this Table the
following abbreviations are made:
Feed l:Natural Gas with the following typical composition
CHq : 94.4$ by volume
C2H6 . 3.0$
C3H8 . 0.5$
C4H10 : 0.2$
CSH12+: 0.2$
. C02 . 0.29
N2 . 1.5$
The supply temperature to the burner.of this feedstock is 150-
2so ac.
Feed 2: Natural Gas with the following typical composition
CH4 : 81.8$ by volume
C2H6 . 2.7$
C3H8 . 0.4$
C4H10 : O.I$
CSH12+: 0.1$
_Cp2 . 0.9$
N2 : 14.0$
C02._is supplied as a moderator gas to the said natural gas in such a
manner that the mass ratio of moderator gas C02 to Natural Gas is
0.6-0.8. The supply temperature to the burner of this feedstock is
280-320 °C~-_
oxidiser l: 99.5$ pure 02 with a temperature of 230-250 °C.
oxidiser 2: a mixture of a gas with 99.5$ pure 02 with 20-30$ (by
mass) of moderator gas. This mixture has a temperature of 250-270 °C
and the moderator gas is steam at a temperature of 280-300 °C.
WO 96103345 PCTIEP95102877
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A number of 9 examples has been presented. The following Table
indicates the distributions of the respective fuels and oxidisers
for these examples. The typical synthesis gas compositions are also
given. The values of n as used in the description and claims are
indicated and passage 1 is the first-or central passage. !
r
W 0 96103345 PCT/EP95/01877
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Table With Examples
Exam 1e number 1 2 g
Value of n 7 6 6
'S Typical synthesis
gas
composition -3 -7 -3
CO [8 Vol, dr ]
CO [B Vol, dr ] 34-35 39-40 34-35
i
H [8 Vol, dr ] 62-63 47-48 62-63
Reactor ressura [MPa]9-5 2-3 5-,
3
Reactor temperature
Ide CI 300-1400 250-1350 300-1400
Passa a 1 T a of feed 1 oxidiser oxidiser 1
as 1
Mass flow [k /s] 1-1.5 1.2-1.8 1-1.5
i
Velocit [m/s] 30-45 80-120 50-75
Passa a 2 T a of oxidiser feed 2 feed 1
as 1
Mass flow jk Js) 2.6-4 0.9-0.6 1.1-1.6
i Velocit [m/s] BO-120 30-45 25-35
- Passa a 3 T a of feed 1 feed 2 oxidiser 1
as
Mass flow [k /s] 2.1-3.1 2.1-3.1 2-3
Velocit [m/s] 30-45 80-120 50-75
Passa a 4 T a of oxidiser feed 2 feed 1
1 as 1
Mass flow [k /s] 2.7-4 0.6-0.9 1.8-2.7
Velocit [m/s] 80-120 30-45 25-35
Passa a S T a of feed 1 oxidiser oxidiser 1
as 1 .
Mass flow [k /s] 2.1-3.1 1.2-1.8 2-3
Velocit [m/s] 30-45 80-120 50-75
Passa a 6 T a of oxidiser feed 2 feed 1
as 1
f
Mass flow [k /s] 3-4.5 0.76-1.1 1-1.5
Velocit [m/s] 80-120 30-45 20-30
) Passa a 7 T a of feed 1
as
Mass flow (k /s1 1-1.5
Velocit [m/s] 30-45
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Table With Examples (Continued)
Exam 1e aumber 4 S 6
Value of n 5 4 3
Typical synthesis
gas
composition -10 -5 -5
CO [~ Vol, dr ]
CO [8 Vol, dr ] 36-37 32-33 32-33
H [fl Vol, dr ] 47-48 62-63 62-63
Reactor ressure [MPa]2-3 I-1.5 2-3
Reactor temperature
[de C] 1200-1300 1300-1400 1300-1400
Passa a 1 T a of as feed 2 feed 1 feed 1
Mass flow [k /s] 1-1.5 - 2-3 0.7-1.1
Velocit [m/sj 40-60 80-120- 45-80
Passa a 2 T a of as oxidiser.2 feed 1 oxidiser 1
Mass flow (k /s] 1.6-2.4 0.6-0.9 1.7-2.6
Velocit [m/s] 95-140 30-45 100-150
Passa a 3 T a of as feed 2 oxidiser feed 1
2
Mass flow [k /s] 2-3 6.2-9.3 0.9-1.3
Velocit [m/s] 40-60 80-120 35-40
Passa a 4. T a of oxidiser feed 1 moderator as
as 2
Mass flow (k /s] 1.6-2.4 1.3-2 0.6-0.9
Velocit [m/s] 70-100 25-35 55-80
Passa a 5 T a of as feed 2
Mass flow [k /s] 1-1.5
Velocit (m/s] 30-45
W 0 96103345 PCT/EP95/02877
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Table With Examples (Continued)
Exam 1e number 7 8 g
Value of n 3 3 2
3 Typical synthesis
gas
composition -5 -3 -5
CO [8 Vol, dr ]
CO [8 Vol, dr ] 32-33 34-35 32-33
H [6 Vol, dr ] 62-63 62-63 62-63
Reactor ressure [MPa]2-3 4-5 7-10
Reactor temperature
[de C] 1300-1400 1300-1400 1300-1400
Passa a 1 T a of as oxidiser feed 1 oxidiser 2
2
Mass flow [k /s] 2.5-3.5 2-3 6-8
Velocit [m/s] 40-60 40-70 95-60 .
Passa a 2 T a of as oxidiser oxidiser feed 1
2 1
Mass flow [k /s] 1.7-2.6 4-6 4-5.6
Velocit [m/s] 100-150 80-120 25-35
Passa a 3 T a of as feed 1 feed 1
Mass flow [k /s] 2.5-3.7 1.3-2
Velocit [m/s] 30-45 30-45
It will.be appreciated by those skilled in the art that any
slit width suitable for the purpose can be applied, dependent on the
burner capacity.
Advantageously, the first or central passage has a diameter up
to 70 mm, whereas the remaining concentric passages have slit widths
in the range of 1-20 mm.
Various modifications of the present invention will become
apparent to those skilled in the art from the foregoing description.
Such modifications are intended to fall within the scope of the
appended claims.
