METHOD TO PRODUCE ENERGY AND CARBON DIOXIDE

METHODE DE PRODUCTION D'ENERGIE ET DE GAZ CARBONIQUE

English Abstract

T 6023 CAN

A B S T R A C T

METHOD TO PRODUCE ENERGY AND CARBON DIOXIDE

A method to produce energy and carbon dioxide, comprising
introducing a stream of essentially oxygen and a stream of
hydrocarbon fuel into a combustion chamber, combusting the
hydrocarbon fuel with the oxygen in the combustion chamber thereby
producing an amount of energy and a stream of combustion gas
comprising carbon dioxide, and using at least a first part of said
amount of energy to drive a turbine thereby generating mechanical
energy. At least a first part of the stream of combustion gas is
cooled and recycled into the combustion chamber so as attenuate the
combustion temperature in said chamber.


CS7.T6023PD

Claims

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T 6023 CAN

C L A I M S

1. A method to produce energy and carbon dioxide, comprising:
- introducing a stream of essentially oxygen and a stream of
hydrocarbon fuel into a combustion chamber;
- combusting the hydrocarbon fuel with the oxygen in the
combustion chamber thereby producing an amount of energy and a
stream of combustion gas comprising carbon dioxide;
- using at least a first part of said amount of energy to drive
a turbine thereby generating mechanical energy; and
- cooling at least a first part of the stream of combustion gas
and recycling said cooled first part of the stream of combustion
gas into the combustion chamber so as attenuate the combustion
temperature in said chamber.
2. The method of claim 1, wherein a second part of the stream of
the combustion gas is introduced into a subsurface earth formation
so as to enhance recovery of oil from said formation.
3. The method of claim 2, wherein the second part of the stream
of the combustion gas is dehydrated prior to introduction into said
earth formation.
4. The method of claim 3, wherein the second part of the stream
of the combustion gas is compressed after dehydration and prior to
introduction into said earth formation.
5. The method of any one of claims 1-4, wherein oxygen of the
stream of oxygen is produced from air which is introduced into
means for producing oxygen from air.
6. The method of any one of claims 1-5, wherein said turbine is
in the form of a steam-turbine and said first part of the amount of
energy is carried in a stream of steam produced in a steam boiler,
said stream of steam being used to drive the steam-turbine.
7. The method of any one of claims 1-5, wherein said turbine is
in the form of a gas-turbine and said first part of the amount of

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energy is carried in the stream of combustion gas, said stream of
combustion gas being used to drive the gas-turbine.
8. The method of claim 7, wherein a second part of said amount of
energy is recovered from the stream of combustion gas after
discharge from the gas-turbine using energy recovery means .
9. The method of claim 8, wherein said second part of the amount
of energy is used to produce a stream of steam using a steam
boiler.
10. The method substantially as described hereinbefore with
reference to the drawings.




CS7.T6023PD

Description

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T 6023 CAN
C~U

~ETHOD TO PRODUCE ENERGY AND CARBON DIOXIDE

The invention relates to a method to produce energy and carbon
dioxide from the combustion of hydrocarbon fuel. In conventional
methods for generating energy and carbon dioxide from the
combustion of hydrocarbon fuel, recovery of the carbon dioxide from
the combustion flue gas often involves costly and complex solvent
processes.
It is an object of the invention to overcome these and other
drawbacks of conventional methods for generating energy and carbon
dioxlde.
In accordance with the invention this object is achieved by a
method to produce energy and carbon dioxide, comprising introducing
a stream of essentially oxygen and a stream of hydrocarbon fuel
into a combustion chamber, combusting the hydrocarbon fuel with the
oxygen in the combustion chamber thereby producing an amount of
energy and a stream of combustion gas comprising carbon dioxide,
using at least a first part of said amount of energy to drive a
turbine thereby generating mechanical energy, cooling at least a
first part of the stream of combustion gas and recycling said
cooled first part of the stream of combustion gas into the
combustion chamber so as attenuate the combustion temperature in
said chamber. In this manner it is achieved that the stream of
combustion gas is essentially free of nitrogen and nitrogen
compounds and oxides.
Advantageously a second part of the stream of combustion gas ~
is introduced into a subsurface earth formation so as to enhance
recovery of oil from said formation. If the stream of hydrocarbon
fuel contains sulphur, it is not required to remove any sulphur
oxides from said second part of the stream of combustion gas sincs
these oxides are disposed in the subsurface earth formation.
Consequently it is not required to operate at high combustion

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temperatures to remove any sulphur oxides which would otherwise
have formed and which would have to be removed for example by a
reaction with a sodium compound, and no additional steps to protect
heat exchanger surfaces from such high temperatures are requi~ed.
The invention will now be explained in more detail with
reference to the accompanying drawings, in which:
Fig. 1 shows schematically a first embodiment of a system for
use in the method according to the invention; and
Fig. 2 shows schematically a second embodiment of a system for
use in the method according to the invention.
Referring to Fig. 1 there is shown an oxygen plant 1 which
produces a stream of essentially oxygen 3 from a stream of air 5
which is introduced into the plant 1. A stream of gaseous
hydrocarbon fuel 7 which is essentially sulphur-free and the stream
of oxygen 3 are introduced into a combustion chamber 9 of a steam
boiler 11 provided with heat exchanging means (not shown). The
hydrocarbon fuel is combusted with the oxygen in the combustion
chamber 9 thereby producing an amount of energy and a stream of
combustion gas 13 comprising carbon dioxide. Since the stream 3
contains essentially oxygen, the stream of combustion gas 13 is
essentially free of nitrogen oxides.
The combustion gas is cooled as it flows along the heat
exchanging means of the steam boiler 11. A first part 15 of the
stream of cooled combustion gas 13 is recycled to the combustion
chamber 9 of the steam boiler 11 by introducing said first part 15
into the stream of oxygan 3.
A first part of the amount of energy produced during the
combustion process is carried in a stream of steam 15 produced in
the steam boiler. The stream of steam 15 drives a steam-turbine 17
thereby providing mechanical energy to a process 19. A stream of
low-pressure steam 21 leaves the steam turbine 17 and flows to a
suitable process 23. Thereafter the low-pressure steam is condensed
in a cooling tower 25, and a stream of water 27 flows back to the
steam boiler 11.

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A second part 29 of the stream of combustion gas 13 is
dehydrated using a dehydrator 31 to produce essentially dry carbon
dioxide. Thereafter the dried carbon dioxide is compressed using a
compressor 33 and transported via a pipeline system 35 to a
location (not shown) where the carbon dioxide is pumped into a
subsurface earth formation so as to enhance recovery of oil from
the earth formation.
Referring now to Fig. 2 there is shown an oxygen plant 40
which produces a stream of essentially oxygen 42 from a stream of
air 44 which is introduced into the plant 40. A stream of gaseous
hydrocarbon fuel 46 which is essen~ially sulphur-free and the
stream of oxygen 42 are introduced into a combustion chamber 48 of
a gas turbine 50. The hydrocarbon fuel is combusted with the oxygen
in the combustion chamber 48 thereby producing an amount of energy
and a stream of combustion gas 52 comprising carbon dioxide.
Similar to the first embodiment shown in Fig. 1, the stream of
combustion gas 52 is essentially free of nitrogen oxides.
A first part of the amount of energy produced during the
combustion process is carried in the combustion gas and is used to
drive a gas-turbine 50. A second part of the amount of energy is
recovered from the stream of combustion gas 52 after discharge from
the gas-turbine 50 by producing a stream of steam 54 using a waste
heat boiler 56, which streaM of steam 54 is then used in a suitable
process 58. The steam is then condensed in a cooling tower 60 and a
stream of water 62 is transported back to the waste heat boiler 56.
The co~bustion gas is cooled as it flows along the waste heat
boiler 56. In order to attenuate the combustion temperature in the
combustio chamber 48, a first part 64 of the stream of cooled
combustion gas 52 is recycled to the combustion chamber 48 of the
gas turbine 50 by introducing said first part 64 into the stream of
oxygen 42.
A second part 66 of the stream of combustion gas 52 is
dehydrated using a dehydrator 68 to produce essentially dry carbon
dioxide. Thereafter the dried carbon dioxide is compressed using a
compressor 70 and transported via a pipeline system 72 to a

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location (not shown) where the carbon dioxide is pumped into a
subsurface earth formation so as to enhance recovery of oil from
the earth formation.
The foregoing description of the invention is merely intended
to be explanatory thereof. Various changes in the details of the
described method may be made within the scope of the appended
claims.

Representative Drawing