CA2499264C - A process and a plant for recycling carbon dioxide emissions from power plants into useful carbonated species - Google Patents
A process and a plant for recycling carbon dioxide emissions from power plants into useful carbonated species Download PDFInfo
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- CA2499264C CA2499264C CA2499264A CA2499264A CA2499264C CA 2499264 C CA2499264 C CA 2499264C CA 2499264 A CA2499264 A CA 2499264A CA 2499264 A CA2499264 A CA 2499264A CA 2499264 C CA2499264 C CA 2499264C
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- 238000010521 absorption reaction Methods 0.000 description 2
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- 229910052791 calcium Inorganic materials 0.000 description 2
- VTVVPPOHYJJIJR-UHFFFAOYSA-N carbon dioxide;hydrate Chemical compound O.O=C=O VTVVPPOHYJJIJR-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical class OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 2
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- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/84—Biological processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/50—Carbon oxides
- B01D2257/504—Carbon dioxide
Abstract
A process is disclosed for recycling carbon dioxide emissions from a fossil-fuel power plant into useful carbonated species. Ohe process primarily comprises the steps of: a) burning the fossil fuel, thereby generating heat and a hot exhaust gas containing CO2; and b) converting the heat into energy.
The process is characterized in that it further comprises the steps of: c) cooling the exhaust gas; and d) biologically transforming the CO2 contained in the cooled exhaust gas into carbonated species, thereby obtaining a low CO2 exhaust gas and producing useful carbonated species. The low CO2 exhaust gas obtained in step d) can be released in the atmosphere without increasing the problem of greenhouse effect.
The process is characterized in that it further comprises the steps of: c) cooling the exhaust gas; and d) biologically transforming the CO2 contained in the cooled exhaust gas into carbonated species, thereby obtaining a low CO2 exhaust gas and producing useful carbonated species. The low CO2 exhaust gas obtained in step d) can be released in the atmosphere without increasing the problem of greenhouse effect.
Description
A PROCESS AND A PLANT FOR RECYCLING CARBON DIOXIDE
EMISSIONS FROM POWER PLANTS INTO USEFUL CARBONATED
SPECIES
FIELD OF THE INVENTION
The present invention relates generally to processes and apparatuses used for energy production in fossil-fuel power plants. More particularly, it concerns a process and a plant for the sequestration of carbon dioxide emissions emanating from fossil-fuel power plants, and for the production of useful carbonated species.
BACKGROUND OF THE INVENTION
Fossil-fuel power plants produce the main part of the energy actually consumed worldwide. Energy is generated from. the combustion of fossil-fuels such as coal, natural gas and fuel oil. The use of biomass to fuel the power plant is also within the scope of this invention. Main exhaust gases formed from such processes may be C02, SO2 and NOx depending on the nature of the fuel used. Treatment systems are already available for reducing SO2 and NOx emissions. However to date, CO2 emissions from fossil-fuel power plants are generally not contained or reduced. These CO2 emissions thus contribute to increase the atmospheric concentration of CO2, the most important greenhouse gas. It is known that such an increase in greenhouse gases causes climate changes which could lead to various environmental problems, such as an increase in violent weather events, significant temperature warming in specific *areas, changes in the precipitation pattern trends and a rise of ocean level.
Moreover, in the next century, a significant increase of carbon dioxide concentrations is expected, unless energy production systems reduce their emissions into the atmosphere. Carbon sequestration consisting of carbon capture, separation and storage or reuse represents potent ways to stabilize and eventually reduce concentration of atmospheric CO2.
EMISSIONS FROM POWER PLANTS INTO USEFUL CARBONATED
SPECIES
FIELD OF THE INVENTION
The present invention relates generally to processes and apparatuses used for energy production in fossil-fuel power plants. More particularly, it concerns a process and a plant for the sequestration of carbon dioxide emissions emanating from fossil-fuel power plants, and for the production of useful carbonated species.
BACKGROUND OF THE INVENTION
Fossil-fuel power plants produce the main part of the energy actually consumed worldwide. Energy is generated from. the combustion of fossil-fuels such as coal, natural gas and fuel oil. The use of biomass to fuel the power plant is also within the scope of this invention. Main exhaust gases formed from such processes may be C02, SO2 and NOx depending on the nature of the fuel used. Treatment systems are already available for reducing SO2 and NOx emissions. However to date, CO2 emissions from fossil-fuel power plants are generally not contained or reduced. These CO2 emissions thus contribute to increase the atmospheric concentration of CO2, the most important greenhouse gas. It is known that such an increase in greenhouse gases causes climate changes which could lead to various environmental problems, such as an increase in violent weather events, significant temperature warming in specific *areas, changes in the precipitation pattern trends and a rise of ocean level.
Moreover, in the next century, a significant increase of carbon dioxide concentrations is expected, unless energy production systems reduce their emissions into the atmosphere. Carbon sequestration consisting of carbon capture, separation and storage or reuse represents potent ways to stabilize and eventually reduce concentration of atmospheric CO2.
2 Several technologies, based on carbon sequestration, are being studied by academic and industrial groups. These are: transformation by algae, sequestration in oceans, storage in depleted oil and natural gas wells and dissolution of pressurized CO2 in water tables. CO2 can also be transformed into more geologically stable forms, such as calcium carbonate.
Transformation of CO2 with algae involves the use of algal photosynthesis.
The gas emitted by power stations is thus directly introduced in basins located nearby. The selected algae must therefore support these environments with harsh conditions. The algae produced could be dried up and used as fuel to supply the power station. This approach reduces the required fuel to supply power, but does not eliminate CO2 production completely.
Sequestration in oceans consists in pumping the carbon dioxide to be disposed of to depths of 1,000 metres below sea level. The technique is based on the fact that CO2 possesses a higher density than water. It is believed that CO2 will sink to the bottom of oceans where lakes of liquid carbon dioxide will be formed. However, as yet, the environmental impact of this technology has not been demonstrated (US 6,475,460). Another way is to bring carbon dioxide and seawater or fresh water into contact to form carbon dioxide hydrate and sinking it in the seawater, fresh water or geological formation under conditions for the stability of carbon dioxide hydrate (CA 2,030,391, patent application US 2003/0055117, patent application US 2003/0017088; US 6,254,667).
Oil and natural gas wells are capable of supporting enormous pressures without leakage. They are therefore an ideal location for the storage of compressed CO2 (patent application CA 2,320,216; US 6,598,398;
US 6,389,814; US 6,170,264). In the petroleum industry, the injection of CO2 in wells to enhance oil recovery is a widely used technique. However, this method only constitutes a temporary storage, since in the medium
Transformation of CO2 with algae involves the use of algal photosynthesis.
The gas emitted by power stations is thus directly introduced in basins located nearby. The selected algae must therefore support these environments with harsh conditions. The algae produced could be dried up and used as fuel to supply the power station. This approach reduces the required fuel to supply power, but does not eliminate CO2 production completely.
Sequestration in oceans consists in pumping the carbon dioxide to be disposed of to depths of 1,000 metres below sea level. The technique is based on the fact that CO2 possesses a higher density than water. It is believed that CO2 will sink to the bottom of oceans where lakes of liquid carbon dioxide will be formed. However, as yet, the environmental impact of this technology has not been demonstrated (US 6,475,460). Another way is to bring carbon dioxide and seawater or fresh water into contact to form carbon dioxide hydrate and sinking it in the seawater, fresh water or geological formation under conditions for the stability of carbon dioxide hydrate (CA 2,030,391, patent application US 2003/0055117, patent application US 2003/0017088; US 6,254,667).
Oil and natural gas wells are capable of supporting enormous pressures without leakage. They are therefore an ideal location for the storage of compressed CO2 (patent application CA 2,320,216; US 6,598,398;
US 6,389,814; US 6,170,264). In the petroleum industry, the injection of CO2 in wells to enhance oil recovery is a widely used technique. However, this method only constitutes a temporary storage, since in the medium
3 term, the displacements of the earth crust are capable of bringing about a release of C02. Moreover, although there are hundreds of depleted sites around the world, their total capacity is after all limited, and there is an obligation to land case the geological formations involved.
The deep water tables are distributed throughout the globe. They generally include salt water and are separated from the surface water tables which constitute the drinking water supplies. The water contained in these natural reservoirs can dissolve the pressurized CO2 and even disperse it in the geological formations. However, the implementation of this technology must always imply a strong concern regarding the proximity of the water tables with the CO2 emission sources.
CO2 sequestration in solid carbonates and/or bicarbonates has already been reported in Lee et al. (US 6,447,437). However, CO2 chemical transformation into bicarbonate fertilizer requires methane, hydrogen and nitrogen. Kato et al. (US 6,270,731) reported CO2 sequestration into carbon powder. However, methane and hydrogen are required. Shibata et al. (US 5,455,013) reported CO2 sequestration into CaCO3. However, the chemical process enables C02 sequestration into CaCO3 only. Other carbonates cannot be obtained.
Although some solutions have been proposed in the past for reducing C02 emissions in general, few of them have shown to be efficient or commercially viable for different reasons. Moreover, a very few, if not none, of the solutions proposed specifically apply to CO2 emissions from fossil-fuel power plants. Thus, there is still a need for a solution for reducing those CO2 emissions from fossil-fuel power plants. With the general concern throughout the world with respect to the urgency of finding a solution to the problem of emissions of greenhouse gases, this need is even more obvious.
The deep water tables are distributed throughout the globe. They generally include salt water and are separated from the surface water tables which constitute the drinking water supplies. The water contained in these natural reservoirs can dissolve the pressurized CO2 and even disperse it in the geological formations. However, the implementation of this technology must always imply a strong concern regarding the proximity of the water tables with the CO2 emission sources.
CO2 sequestration in solid carbonates and/or bicarbonates has already been reported in Lee et al. (US 6,447,437). However, CO2 chemical transformation into bicarbonate fertilizer requires methane, hydrogen and nitrogen. Kato et al. (US 6,270,731) reported CO2 sequestration into carbon powder. However, methane and hydrogen are required. Shibata et al. (US 5,455,013) reported CO2 sequestration into CaCO3. However, the chemical process enables C02 sequestration into CaCO3 only. Other carbonates cannot be obtained.
Although some solutions have been proposed in the past for reducing C02 emissions in general, few of them have shown to be efficient or commercially viable for different reasons. Moreover, a very few, if not none, of the solutions proposed specifically apply to CO2 emissions from fossil-fuel power plants. Thus, there is still a need for a solution for reducing those CO2 emissions from fossil-fuel power plants. With the general concern throughout the world with respect to the urgency of finding a solution to the problem of emissions of greenhouse gases, this need is even more obvious.
4 SUMMARY OF THE INVENTION
An object of the present invention is to provide a process and a fossil-fuel power plant that satisfy the above mentioned need.
Accordingly, the present invention provides a process comprising:
a) combustion of a fossil fuel, thereby generating heat and an exhaust gas containing C02;
b) converting said heat into energy;
the process being characterized in that it comprises the steps of:
c) cooling at least a portion of the exhaust gas to produce a cooled exhaust gas; and d) reducing the amount of CO2 contained in the cooled exhaust gas by biologically transforming said CO2 into carbonated species; thereby obtaining a low CO2 exhaust gas, wherein step d) comprises:
contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO2 and producing a solution containing hydrogen ions and carbonate ions, wherein said hydration is catalyzed by an enzyme comprising carbonic anhydrase or an analogue thereof.
The present invention also provides a power plant for producing energy from fossil fuel and recycling carbon dioxide emissions into carbonated species, the plant comprising:
a combustion unit for burning fossil fuel, thereby producing heat and an exhaust gas containing C02;
means for converting the heat into energy;
the plant being characterized in that it comprises:
4a means for cooling at least a portion of the exhaust gas to produce a cooled exhaust gas;
means for contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO2 to dissolve into the aqueous liquid phase;
biological catalyzing means for biologically transforming at least a portion of the dissolved CO2 into hydrogen ions and carbonate ions and producing a solution containing the same, wherein the hydration is catalyzed by an enzyme comprising carbonic anhydrase or an analogue thereof; and precipitation means for precipitating carbonated species from the carbonate ions.
The invention may comprise a step where the CO2 emissions from the fossil-fuel power plant are transformed by means of a biological process into different useful carbonated species, such as calcium carbonate, a geological natural product.
More particularly, in accordance with the present invention, there is provided a process for recycling carbon dioxide emissions from a fossil-fuel power plant into useful carbonated species, which process primarily comprises the steps of: a) combustion of a fossil fuel, thereby generating heat and a hot exhaust gas containing CO2; and b) converting the heat into energy. The process is characterized in that it further comprises the steps of: c) cooling the exhaust gas;
and d) biologically transforming at least a portion of the CO2 contained in the cooled exhaust gas into carbonated species, thereby obtaining a low CO2 exhaust gas and producing useful carbonated species. The low CO2 exhaust gas obtained in step d) can be released in the atmosphere without increasing the problem of greenhouse effect.
4b By biological process, it is meant a process involving the activity of living organisms.
More particularly, the step d) of biologically transforming the CO2 defined above preferably comprises the steps of. catalyzing the hydration of at least a portion of the CO2 contained in the exhaust gas, and producing a solution containing hydrogen ions and carbonate ions. Then, metal ions are added to the solution, and the pH is adjusted to precipitate a carbonate of that metal. These metal ions are preferably selected from the group consisting of calcium, barium, magnesium and sodium ions. More preferably, Ca++ is used and the carbonate obtained is CaCO3.
The hydration is catalyzed by a biocatalyst capable of catalyzing the hydration of dissolved CO2 into hydrogen ions and bicarbonate ions. More preferably, the biocatalyst is selected from the group consisting of enzyme, cellular organelle, mammal cells and vegetal cells. Most preferably, the
An object of the present invention is to provide a process and a fossil-fuel power plant that satisfy the above mentioned need.
Accordingly, the present invention provides a process comprising:
a) combustion of a fossil fuel, thereby generating heat and an exhaust gas containing C02;
b) converting said heat into energy;
the process being characterized in that it comprises the steps of:
c) cooling at least a portion of the exhaust gas to produce a cooled exhaust gas; and d) reducing the amount of CO2 contained in the cooled exhaust gas by biologically transforming said CO2 into carbonated species; thereby obtaining a low CO2 exhaust gas, wherein step d) comprises:
contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO2 and producing a solution containing hydrogen ions and carbonate ions, wherein said hydration is catalyzed by an enzyme comprising carbonic anhydrase or an analogue thereof.
The present invention also provides a power plant for producing energy from fossil fuel and recycling carbon dioxide emissions into carbonated species, the plant comprising:
a combustion unit for burning fossil fuel, thereby producing heat and an exhaust gas containing C02;
means for converting the heat into energy;
the plant being characterized in that it comprises:
4a means for cooling at least a portion of the exhaust gas to produce a cooled exhaust gas;
means for contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO2 to dissolve into the aqueous liquid phase;
biological catalyzing means for biologically transforming at least a portion of the dissolved CO2 into hydrogen ions and carbonate ions and producing a solution containing the same, wherein the hydration is catalyzed by an enzyme comprising carbonic anhydrase or an analogue thereof; and precipitation means for precipitating carbonated species from the carbonate ions.
The invention may comprise a step where the CO2 emissions from the fossil-fuel power plant are transformed by means of a biological process into different useful carbonated species, such as calcium carbonate, a geological natural product.
More particularly, in accordance with the present invention, there is provided a process for recycling carbon dioxide emissions from a fossil-fuel power plant into useful carbonated species, which process primarily comprises the steps of: a) combustion of a fossil fuel, thereby generating heat and a hot exhaust gas containing CO2; and b) converting the heat into energy. The process is characterized in that it further comprises the steps of: c) cooling the exhaust gas;
and d) biologically transforming at least a portion of the CO2 contained in the cooled exhaust gas into carbonated species, thereby obtaining a low CO2 exhaust gas and producing useful carbonated species. The low CO2 exhaust gas obtained in step d) can be released in the atmosphere without increasing the problem of greenhouse effect.
4b By biological process, it is meant a process involving the activity of living organisms.
More particularly, the step d) of biologically transforming the CO2 defined above preferably comprises the steps of. catalyzing the hydration of at least a portion of the CO2 contained in the exhaust gas, and producing a solution containing hydrogen ions and carbonate ions. Then, metal ions are added to the solution, and the pH is adjusted to precipitate a carbonate of that metal. These metal ions are preferably selected from the group consisting of calcium, barium, magnesium and sodium ions. More preferably, Ca++ is used and the carbonate obtained is CaCO3.
The hydration is catalyzed by a biocatalyst capable of catalyzing the hydration of dissolved CO2 into hydrogen ions and bicarbonate ions. More preferably, the biocatalyst is selected from the group consisting of enzyme, cellular organelle, mammal cells and vegetal cells. Most preferably, the
5 biocatalyst is the enzyme carbonic anhydrase or an analogue thereof.
CO2 transformation takes place inside a bioreactor and is performed by a biocatalyst which accelerates the transformation of CO2 into bicarbonate in an aqueous environment. The bicarbonate can then be precipitated into a stable solid product.
This invention thus proposes the integration of a CO2 transformation process into a fossil-fuel power plant in order to produce bicarbonate species which are useful by-products, and thereby reducing at the same time the CO2 emissions. This CO2 transformation process is based on a biological reactor which enables CO2 transformation into bicarbonate in an aqueous environment. The CO2 is then precipitated into a stable solid product, safe for the environment. As can be appreciated, in the present invention, only water, a biocatalyst and a cation source are required for carbon dioxide sequestration.
In accordance with a preferred aspect of the invention, step d) of biologically transforming the CO2 comprises the step of: feeding liquid H2O
and at least a portion of the exhaust gas, preferably all, into a bioreactor containing therein a reaction chamber filled with the biocatalyst. The biocatalyst is optionally immobilized on solid supports packing the bioreactor or in suspension in a liquid phase. In that latter case, the biocatalyst may be either free in the aqueous liquid phase, immobilized on solid supports or entrapped inside a solid matrix.
The present invention also provides a power plant for producing energy from fossil fuel, and recycling carbon dioxide emissions into carbonated species. The plant comprises a combustion unit for burning fossil fuel,
CO2 transformation takes place inside a bioreactor and is performed by a biocatalyst which accelerates the transformation of CO2 into bicarbonate in an aqueous environment. The bicarbonate can then be precipitated into a stable solid product.
This invention thus proposes the integration of a CO2 transformation process into a fossil-fuel power plant in order to produce bicarbonate species which are useful by-products, and thereby reducing at the same time the CO2 emissions. This CO2 transformation process is based on a biological reactor which enables CO2 transformation into bicarbonate in an aqueous environment. The CO2 is then precipitated into a stable solid product, safe for the environment. As can be appreciated, in the present invention, only water, a biocatalyst and a cation source are required for carbon dioxide sequestration.
In accordance with a preferred aspect of the invention, step d) of biologically transforming the CO2 comprises the step of: feeding liquid H2O
and at least a portion of the exhaust gas, preferably all, into a bioreactor containing therein a reaction chamber filled with the biocatalyst. The biocatalyst is optionally immobilized on solid supports packing the bioreactor or in suspension in a liquid phase. In that latter case, the biocatalyst may be either free in the aqueous liquid phase, immobilized on solid supports or entrapped inside a solid matrix.
The present invention also provides a power plant for producing energy from fossil fuel, and recycling carbon dioxide emissions into carbonated species. The plant comprises a combustion unit for burning fossil fuel,
6 thereby producing heat and an exhaust gas containing C02; and conventional means for converting the heat into energy. The plant is characterized in that it further comprises: means for cooling the exhaust gas; and biological means for biologically transforming at least a portion of the CO2 from the cooled exhaust gas into hydrogen ions and carbonate ions, and means for precipitating carbonated species.
The biological means preferably comprises a bioreactor including a reaction chamber filled with a biocatalyst capable of catalyzing the hydration of dissolved CO2 into hydrogen ions and bicarbonate ions. The reaction chamber preferably comprises:
- a liquid inlet for receiving an aqueous liquid;
- a gas inlet for receiving the cooled exhaust gas to be treated;
- a gas outlet for releasing a low CO2 gas; and a liquid outlet for releasing a solution containing carbonate ions.
Also preferably, the precipitation means comprises a precipitation vessel, wherein the bicarbonate ions can react with metal ions and precipitate a carbonate of that metal. -GENERAL DESCRIPTION OF THE INVENTION
CO2 production in a fossil fuel power plant CO2 is produced during combustion of fossil fuels such as coal, natural gas or fuel oil (Equation 1). For the purpose of the present invention, fossil-fuel power plant is also directed to power plants using biomass as the fuel. In the case of a coal power plant, the heat released during this combustion is used to heat water and produce steam which then passes through steam turbines coupled to electric alternators leading to electricity generation. In
The biological means preferably comprises a bioreactor including a reaction chamber filled with a biocatalyst capable of catalyzing the hydration of dissolved CO2 into hydrogen ions and bicarbonate ions. The reaction chamber preferably comprises:
- a liquid inlet for receiving an aqueous liquid;
- a gas inlet for receiving the cooled exhaust gas to be treated;
- a gas outlet for releasing a low CO2 gas; and a liquid outlet for releasing a solution containing carbonate ions.
Also preferably, the precipitation means comprises a precipitation vessel, wherein the bicarbonate ions can react with metal ions and precipitate a carbonate of that metal. -GENERAL DESCRIPTION OF THE INVENTION
CO2 production in a fossil fuel power plant CO2 is produced during combustion of fossil fuels such as coal, natural gas or fuel oil (Equation 1). For the purpose of the present invention, fossil-fuel power plant is also directed to power plants using biomass as the fuel. In the case of a coal power plant, the heat released during this combustion is used to heat water and produce steam which then passes through steam turbines coupled to electric alternators leading to electricity generation. In
7 PCT/CA2003/001496 the case of a natural gas power plant, the fuel is burned directly in gas turbines coupled to electric alternators.
CxHy + (x+y/4) 02 x C02+y/2 H2O Equation 1 Other gases may also be produced by combustion, namely SO2 and NO5 , given the original sulphur and nitrogen content of the used fuel. These other gases are encountered mainly in coal power plants.
Flue gas exhausting from combustion chambers and containing CO2 is discharged directly to the atmosphere. In the context of this invention, CO2 emissions are treated and reduced by a biological process.
In the case of coal power plants, flue gas has first to be cooled in order to have a temperature that does not lead to the ,denaturizing (free and/or immobilized) of the biocatalyst. Gas cooling is obtained with any type of heat exchanging device, and the recovered energy is preferably used to increase the process efficiency. The heat could, for example, be used to pre-heat the air required for combustion, or to supply energy for additional turbines. The gas is then preferably treated to remove excess ash, SO2 and NOx, in order that the gas be of optimum quality for the biological process. Ash can be removed using units such as electrostatic precipitators and fabric filters. SO2 can be removed using scrubber units and NOx using burners or catalytic systems leading to the conversion of NOx to N2 and H2O. These units, which are used to remove ash, SO2 or NOx, are already known in prior art and do not need further description.
CO2 transformation in a biological process ,Gas phase containing CO2 with appropriate level of ash, SO2, NOx and at appropriate temperature and pressure, is then fed to the biological process, enabling CO2 transformation into bicarbonate and hydrogen ions, and then to useful carbonated species. This biological process is preferably performed in a biological reactor where CO2 transformation takes place.
CxHy + (x+y/4) 02 x C02+y/2 H2O Equation 1 Other gases may also be produced by combustion, namely SO2 and NO5 , given the original sulphur and nitrogen content of the used fuel. These other gases are encountered mainly in coal power plants.
Flue gas exhausting from combustion chambers and containing CO2 is discharged directly to the atmosphere. In the context of this invention, CO2 emissions are treated and reduced by a biological process.
In the case of coal power plants, flue gas has first to be cooled in order to have a temperature that does not lead to the ,denaturizing (free and/or immobilized) of the biocatalyst. Gas cooling is obtained with any type of heat exchanging device, and the recovered energy is preferably used to increase the process efficiency. The heat could, for example, be used to pre-heat the air required for combustion, or to supply energy for additional turbines. The gas is then preferably treated to remove excess ash, SO2 and NOx, in order that the gas be of optimum quality for the biological process. Ash can be removed using units such as electrostatic precipitators and fabric filters. SO2 can be removed using scrubber units and NOx using burners or catalytic systems leading to the conversion of NOx to N2 and H2O. These units, which are used to remove ash, SO2 or NOx, are already known in prior art and do not need further description.
CO2 transformation in a biological process ,Gas phase containing CO2 with appropriate level of ash, SO2, NOx and at appropriate temperature and pressure, is then fed to the biological process, enabling CO2 transformation into bicarbonate and hydrogen ions, and then to useful carbonated species. This biological process is preferably performed in a biological reactor where CO2 transformation takes place.
8 This transformation is catalyzed by a biocatalyst accelerating CO2 transformation. The biocatalyst is a biological entity which can transform a substrate in one or more products. The biocatalyst is preferably an enzyme, a cellular organelle (mitochondrion, membrane, etc.), and animal, vegetal or human cells. More preferably, the biocatalyst is the enzyme carbonic anhydrase but may be any biological catalyst enabling CO2 transformation. CO2 transformation reaction is the following:
C02 +H20 HCO3+H+ Equation 2 This reaction is natural. It is at the basis of CO2 transportation and removal phenomenon in the human body and in most living beings.
The biological catalyst may be free or immobilized inside the biological reactor. An example of a bioreactor which could be used for biological transformation of CO2 is described in "Process and Apparatus for the Treatment of Carbon Dioxide with Carbonic Anhydrase" (Blais et al.)(CA, 2,291,785; W098/55210). In this process, carbonic anhydrase is immobilized onto solid supports. Solid supports can be made of various organic and inorganic material and have shapes proper to packed columns. The gas phase containing CO2 enters at the bottom of the packed column and the liquid phase enters at the top of the column. Both phases flow counter currently and close contact of liquid and gas phases is promoted by a solid support having immobilized enzymes on its surface.
Gaseous CO2 is then transferred to the liquid phase where it dissolves and then is transformed according to Equation 2. The liquid flows in and out of the column and is treated for precipitating the bicarbonate ions produced by the bioreaction.
Another biological reactor with free and/or immobilized enzymes for CO2 transformation into bicarbonate is the following.
C02 +H20 HCO3+H+ Equation 2 This reaction is natural. It is at the basis of CO2 transportation and removal phenomenon in the human body and in most living beings.
The biological catalyst may be free or immobilized inside the biological reactor. An example of a bioreactor which could be used for biological transformation of CO2 is described in "Process and Apparatus for the Treatment of Carbon Dioxide with Carbonic Anhydrase" (Blais et al.)(CA, 2,291,785; W098/55210). In this process, carbonic anhydrase is immobilized onto solid supports. Solid supports can be made of various organic and inorganic material and have shapes proper to packed columns. The gas phase containing CO2 enters at the bottom of the packed column and the liquid phase enters at the top of the column. Both phases flow counter currently and close contact of liquid and gas phases is promoted by a solid support having immobilized enzymes on its surface.
Gaseous CO2 is then transferred to the liquid phase where it dissolves and then is transformed according to Equation 2. The liquid flows in and out of the column and is treated for precipitating the bicarbonate ions produced by the bioreaction.
Another biological reactor with free and/or immobilized enzymes for CO2 transformation into bicarbonate is the following.
9 The bioreactor consists of a chamber containing biocatalyst particles. The gas to be treated enters at the bottom of the chamber. A diffusion system is responsible for the uniform distribution of the gas phase at the bottom of the chamber and is designed for minimum bubble diameter. These conditions are required to optimize gas-liquid contact. An agitation device (magnetic or mechanical) can also be used to assure uniform biocatalyst distribution. Liquid phase enables gas dissolution and thus the biocatalytic reaction. In this process, the biocatalyst (preferably carbonic anhydrase, but may be any biological catalyst) is free in the liquid phase and/or immobilized onto a solid support and/or entrapped inside a solid matrix.
These particles are moving freely in the liquid and are prevented from exiting the chamber by a membrane or filter. The liquid flows in and out of the chamber and is treated for precipitation of the bicarbonate ions produced by the bioreaction.
As mentioned, bicarbonate ions produced in these two types of bioreactors are preferably precipitated and finally sequestrated. This precipitation is obtained by combining bicarbonate ions to cations. Cations used are preferably calcium, barium, magnesium, sodium or any cation that could lead to the formation of carbonate or bicarbonate salts. As shown in Figure 2, a potential source of cations is the reagent solution coming out of the SO2 treatment unit. Bicarbonate ions can also be used directly in other chemical or biological processes.
In summary, CO2 is to be transformed, for example into calcium carbonate, in the biological process, according to the following reactions:
C02 dissolved + H2O H+ + HCO3 HCO3 = H+ + 0032"
0032 + Ca2+ CaCO3 The coupling of the biological process for CO2 removal and transformation to a fossil-fuel power plant leads to a reduction of CO2 emissions into the atmosphere and an increase energy efficiency of the plant. Furthermore, the required cooling of the flue gas enabling proper operation of the 5 bioreactor is coupled with energy recovery systems that produce additional power output for the power plant.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a flow sheet of a preferred embodiment of the process according to the invention, in the context of power plant processes.
These particles are moving freely in the liquid and are prevented from exiting the chamber by a membrane or filter. The liquid flows in and out of the chamber and is treated for precipitation of the bicarbonate ions produced by the bioreaction.
As mentioned, bicarbonate ions produced in these two types of bioreactors are preferably precipitated and finally sequestrated. This precipitation is obtained by combining bicarbonate ions to cations. Cations used are preferably calcium, barium, magnesium, sodium or any cation that could lead to the formation of carbonate or bicarbonate salts. As shown in Figure 2, a potential source of cations is the reagent solution coming out of the SO2 treatment unit. Bicarbonate ions can also be used directly in other chemical or biological processes.
In summary, CO2 is to be transformed, for example into calcium carbonate, in the biological process, according to the following reactions:
C02 dissolved + H2O H+ + HCO3 HCO3 = H+ + 0032"
0032 + Ca2+ CaCO3 The coupling of the biological process for CO2 removal and transformation to a fossil-fuel power plant leads to a reduction of CO2 emissions into the atmosphere and an increase energy efficiency of the plant. Furthermore, the required cooling of the flue gas enabling proper operation of the 5 bioreactor is coupled with energy recovery systems that produce additional power output for the power plant.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a flow sheet of a preferred embodiment of the process according to the invention, in the context of power plant processes.
10 Figure 2 is a flow sheet of a further preferred embodiment of the process according to the invention, in the context of power plant processes.
MORE DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Figure 1 shows a flow sheet where a biological process is integrated to energy generation processes.
In this diagram, the nature of the fossil fuel (10), either coal (12) or natural gas (14), used to power the plant leads to two different branches.
In the case of coal (12), the fuel is burned in a combustion chamber (16);
the heat (17) is ,used to produce steam from water in a heat recovery steam generator system (18). The steam propels turbines and alternators (20) producing electric power. The flue gas (22) exiting the combustion chamber (16) is treated to remove ash, NOx and/or SO2 (23). In the current configuration of power plants, the gas is finally exhausted by a stack (24).
In the context of this invention, the gas (26) is not exhausted at this stage, but rather sent to additional heat exchangers and energy recovery systems (28) to cool it down to an adequate temperature for the biological process.
Energy is produced by this step. The cooled gas (30) is then treated in a gas treatment unit (32) to remove additional contaminants that may be
MORE DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Figure 1 shows a flow sheet where a biological process is integrated to energy generation processes.
In this diagram, the nature of the fossil fuel (10), either coal (12) or natural gas (14), used to power the plant leads to two different branches.
In the case of coal (12), the fuel is burned in a combustion chamber (16);
the heat (17) is ,used to produce steam from water in a heat recovery steam generator system (18). The steam propels turbines and alternators (20) producing electric power. The flue gas (22) exiting the combustion chamber (16) is treated to remove ash, NOx and/or SO2 (23). In the current configuration of power plants, the gas is finally exhausted by a stack (24).
In the context of this invention, the gas (26) is not exhausted at this stage, but rather sent to additional heat exchangers and energy recovery systems (28) to cool it down to an adequate temperature for the biological process.
Energy is produced by this step. The cooled gas (30) is then treated in a gas treatment unit (32) to remove additional contaminants that may be
11 harmful to the biological process, and finally, CO2 is removed by the bioreactor (34) and the low CO2 gas (36) is blown to the atmosphere.
In the case of natural gas (14), the fuel (14) is burned directly in the turbine (38), and the intermediary step of steam production is not present in the main power production stage, although it may be used in subsequent heat recovery stages. The rest of the process is analog to that of the left branch (coal).
Figure 2 is a flow sheet schematically showing the integration of the biological process (32) to a SO2 treatment unit (40).
This diagram shows the cross-linking that may be performed between the.
biological process, which produces carbonate and/or bicarbonate ions (33), and the SO2 treatment unit (40) present in the current power plant process.
To remove SO2 from the flue gas (42), a reagent solution (44) is required.
An analog solution is also required for the biological process (32). This solution (44), readily available from either sub-processes, may be used in closed loop for both processes.
Experimental results The feasibility of treating flue gas from power plant by a biological process has been demonstrated. The lab scale biological process enabled CO2 absorption and its transformation into CaCO3 The biological process was performed with a 3 operation units each comprising a 3L-bioreactor containing 2 L of packing material with immobilized carbonic anhydrase for CO2 absorption. The units also included two ion exchange columns required for recovering and concentrating the bicarbonate ions and a precipitation and sedimentation vessel for formation and recovery of solid CaCO3. The bioreactor used was similar to the one described in "Process and Apparatus for the Treatment of Carbon Dioxide with Carbonic Anhydrase" (Blais et al.)(CA 2,291,785; W098/55210), and was operated at room temperature and atmospheric pressure. Gas phases with CO2
In the case of natural gas (14), the fuel (14) is burned directly in the turbine (38), and the intermediary step of steam production is not present in the main power production stage, although it may be used in subsequent heat recovery stages. The rest of the process is analog to that of the left branch (coal).
Figure 2 is a flow sheet schematically showing the integration of the biological process (32) to a SO2 treatment unit (40).
This diagram shows the cross-linking that may be performed between the.
biological process, which produces carbonate and/or bicarbonate ions (33), and the SO2 treatment unit (40) present in the current power plant process.
To remove SO2 from the flue gas (42), a reagent solution (44) is required.
An analog solution is also required for the biological process (32). This solution (44), readily available from either sub-processes, may be used in closed loop for both processes.
Experimental results The feasibility of treating flue gas from power plant by a biological process has been demonstrated. The lab scale biological process enabled CO2 absorption and its transformation into CaCO3 The biological process was performed with a 3 operation units each comprising a 3L-bioreactor containing 2 L of packing material with immobilized carbonic anhydrase for CO2 absorption. The units also included two ion exchange columns required for recovering and concentrating the bicarbonate ions and a precipitation and sedimentation vessel for formation and recovery of solid CaCO3. The bioreactor used was similar to the one described in "Process and Apparatus for the Treatment of Carbon Dioxide with Carbonic Anhydrase" (Blais et al.)(CA 2,291,785; W098/55210), and was operated at room temperature and atmospheric pressure. Gas phases with CO2
12 concentrations ranging from 0.5 to 12% were efficiently treated with the bioreactor. CO2 removal rate ranged from 1,47 x 10-4 to 4,5 x 10"3 mol CO2/min. Bicarbonate ions produced were recovered and concentrated in ion exchange columns. The removal of ions enabled the recycling of the CO2 absorbent used in the bioreactor. A carbonate/bicarbonate rich solution was obtained following regeneration of ion exchangers. A calcium source, CaCl2 was added to the bicarbonate/carbonate rich solution, conducting to the formation of precipitated calcium carbonate. A carbon mass balance indicated that carbon dioxide removed from the gas was recovered as precipitated CaCO3.
These results indicate that the biological process can be used to manage CO2 emissions from power plants. Moreover, valuable products such as CaCO3 are produced.
Although the present invention has been explained hereinabove by way of preferred embodiments thereof, it should be understood that the invention is not limited to these precise embodiments and that various changes and modifications may be effected therein without departing from the scope or spirit of the invention.
These results indicate that the biological process can be used to manage CO2 emissions from power plants. Moreover, valuable products such as CaCO3 are produced.
Although the present invention has been explained hereinabove by way of preferred embodiments thereof, it should be understood that the invention is not limited to these precise embodiments and that various changes and modifications may be effected therein without departing from the scope or spirit of the invention.
Claims (68)
1. A process comprising:
a) combustion of a fossil fuel, thereby generating heat and an exhaust gas containing CO2;
b) converting said heat into energy;
the process being characterized in that it comprises the steps of:
c) cooling at least a portion of the exhaust gas to produce a cooled exhaust gas; and d) reducing the amount of CO2 contained in the cooled exhaust gas by biologically transforming said CO2 into carbonated species; thereby obtaining a low CO2 exhaust gas, wherein step d) comprises:
contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO2 and producing a solution containing hydrogen ions and carbonate ions, wherein said hydration is catalyzed by an enzyme comprising carbonic anhydrase or an analogue thereof.
a) combustion of a fossil fuel, thereby generating heat and an exhaust gas containing CO2;
b) converting said heat into energy;
the process being characterized in that it comprises the steps of:
c) cooling at least a portion of the exhaust gas to produce a cooled exhaust gas; and d) reducing the amount of CO2 contained in the cooled exhaust gas by biologically transforming said CO2 into carbonated species; thereby obtaining a low CO2 exhaust gas, wherein step d) comprises:
contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO2 to dissolve into the aqueous liquid phase and catalyzing the hydration of at least a portion of the dissolved CO2 and producing a solution containing hydrogen ions and carbonate ions, wherein said hydration is catalyzed by an enzyme comprising carbonic anhydrase or an analogue thereof.
2. The process of claim 1, wherein step d) comprises the step of feeding the aqueous liquid phase and the cooled exhaust gas into a bioreactor.
3. The process of claim 2, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is free in the aqueous liquid phase.
4. The process of claim 2, wherein the enzyme is immobilised on a solid support which is in suspension in the aqueous liquid phase.
5. The process of claim 2, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is entrapped inside a matrix which is in suspension in the aqueous liquid phase.
6. The process of claim 2, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is entrapped inside a matrix in the bioreactor.
7. The process of claim 2, wherein the reaction chamber is filled with the enzyme.
8. The process of claim 2, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is immobilized on solid support packing filling the bioreactor.
9. The process of claim 2, wherein the enzyme is suspended in the aqueous liquid phase, the enzyme being free, immobilized on supports or entrapped inside a matrix or a combination thereof.
10. The process of claim 9, comprising retaining the enzyme within the bioreactor.
11. The process of claim 10, wherein the retaining of the enzyme within the bioreactor is performed using a membrane or a filter.
12. The process of any one of claims 2 to 11, wherein in step d) the contacting of the aqueous liquid phase with the cooled exhaust gas is facilitated by uniformly distributing the cooled exhaust gas into the aqueous liquid phase in a bottom part of the bioreactor.
13. The process of any one of claims 2 to 12, comprising agitating the aqueous liquid phase within the bioreactor.
14. The process of any one of claims 1 to 13, wherein step d) comprises adding to the solution cations, and adjusting the pH of the solution to precipitate a carbonated species of the cation.
15. The process of claim 14, wherein the cations are selected from the group consisting of calcium ions, barium ions, magnesium ions and sodium ions.
16. The process of claim 15, wherein the cations are Ca++ and the carbonated species is CaCO3.
17. The process of any one of claims 1 to 16, wherein the carbonated species comprise precipitates.
18. The process of claim 17, wherein the precipitates are separated from the solution.
19. The process of claim 17, wherein the precipitates comprise stable solid products.
20. The process of any one of claims 1 to 16, wherein the carbonated species consist of precipitates.
21. The process of any one of claims 1 to 20, wherein the cooling of the exhaust gas comprises passing the exhaust gas through a heat exchanger.
22. The process of claim 21, wherein heat removed by the heat exchanger is recovered to convert into energy.
23. The process of any one of claims 1 to 22, comprising removing additional contaminants contained in the exhaust gas.
24. The process of any one of claims 1 to 23, wherein the removing of the additional contaminants contained in the exhaust gas is done while the cooling of the exhaust gas is performed.
25. The process of claim 23 or 24, wherein the additional contaminants are removed from the exhaust gas by scrubbing.
26. The process of claim 25, wherein the additional contaminants removed by scrubbing are selected from the group consisting of ash, NO x and SO2.
27. The process of any one of claims 23 to 26, wherein the step of removing the additional contaminants from the exhaust gas is performed prior to step d).
28. The process of any one of claims 1 to 27, wherein in step c) the exhaust gas is cooled to a temperature sufficientto maintain a desired catalytic effect of the carbonic anhydrase or the analog thereof.
29. The process of claim 28, wherein in step c) the temperature to which the exhaust gas is cooled avoids a given denaturing of free carbonic anhydrase.
30. The process of claim 28, wherein in step c) the temperature to which the exhaust gas is cooled avoids a given denaturing of immobilized carbonic anhydrase.
31. The process of claim 28, wherein in step c) the temperature to which the exhaust gas is cooled avoids a given denaturing of free and immobilized carbonic anhydrase.
32. The process of any one of claims 1 to 31, wherein the step c) of cooling is performed so as to remove heat from the exhaust gas, the removed heat being recycled into step b) of the process.
33. The process of any one of claims 1 to 32, wherein in step d) the contacting of the aqueous liquid phase with the cooled exhaust gas is performed counter-currently.
34. The process of claim 33, wherein in step d) the aqueous liquid phase flows downward and the cooled exhaust gas flows upward.
35. The process of any one of claims 1 to 34, wherein the fossil fuel comprises coal.
36. The process of any one of claims 1 to 35, wherein the exhaust gas has a CO2 concentration between 0.5% and 12%.
37. The process of any one of claims 1 to 36, wherein the solution containing hydrogen ions and carbonate ions is treated to remove the carbonated species and is subsequently recycled back to be used as the aqueous liquid phase in step d).
38. A power plant for producing energy from fossil fuel and recycling carbon dioxide emissions into carbonated species, the plant comprising:
a combustion unit for burning fossil fuel, thereby producing heat and an exhaust gas containing CO2;
means for converting the heat into energy;
the plant being characterized in that it comprises:
means for cooling at least a portion of the exhaust gas to produce a cooled exhaust gas;
means for contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO2 to dissolve into the aqueous liquid phase;
biological catalyzing means for biologically transforming at least a portion of the dissolved CO2 into hydrogen ions and carbonate ions and producing a solution containing the same, wherein the hydration is catalyzed by an enzyme comprising carbonic anhydrase or an analogue thereof; and precipitation means for precipitating carbonated species from the carbonate ions.
a combustion unit for burning fossil fuel, thereby producing heat and an exhaust gas containing CO2;
means for converting the heat into energy;
the plant being characterized in that it comprises:
means for cooling at least a portion of the exhaust gas to produce a cooled exhaust gas;
means for contacting an aqueous liquid phase with the cooled exhaust gas to cause at least a portion of the CO2 to dissolve into the aqueous liquid phase;
biological catalyzing means for biologically transforming at least a portion of the dissolved CO2 into hydrogen ions and carbonate ions and producing a solution containing the same, wherein the hydration is catalyzed by an enzyme comprising carbonic anhydrase or an analogue thereof; and precipitation means for precipitating carbonated species from the carbonate ions.
39. The power plant of claim 38, wherein the means for cooling the exhaust gas comprise a heat exchanger.
40. The power plant of claim 38 or 39, wherein the means for contacting the aqueous liquid phase with the cooled exhaust gas and the biological catalyzing means comprise a bioreactor.
41. The power plant of claim 38, wherein the means for contacting the aqueous liquid phase with the cooled exhaust gas comprise a bioreactor comprising a reaction chamber.
42. The power plant of claim 41, wherein the reaction chamber comprises:
a liquid inlet for receiving the aqueous liquid phase;
a gas inlet for receiving the cooled exhaust gas to be treated;
a gas outlet for releasing a CO2-depleted gas; and a liquid outlet for releasing the solution.
a liquid inlet for receiving the aqueous liquid phase;
a gas inlet for receiving the cooled exhaust gas to be treated;
a gas outlet for releasing a CO2-depleted gas; and a liquid outlet for releasing the solution.
43. The power plant of claim 42, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is free in the aqueous liquid phase.
44. The power plant of claim 42, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is immobilised on a solid support which is in suspension in the aqueous liquid phase.
45. The power plant of claim 42, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is entrapped inside a matrix which is in suspension in the aqueous liquid phase.
46. The power plant of claim 42, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is entrapped inside a matrix in the reaction chamber of the bioreactor.
47. The power plant of claim 42, wherein the enzyme comprises carbonic anhydrase or an analogue thereof that is immobilized on solid supports packing the reaction chamber of the bioreactor.
48. The power plant of claim 42, wherein the bioreactor comprises a membrane or filter for retaining the enzyme within the reaction chamber.
49. The power plant of any one of claims 42 to 48, wherein the gas inlet comprises a distributor for uniformly distributing the cooled exhaust gas into a bottom part of the reaction chamber containing the aqueous liquid phase.
50. The power plant of any one of claims 38 to 49, wherein the precipitation means comprises a precipitation vessel to react the bicarbonate ions with metal ions and precipitate a carbonate of said metal.
51. The power plant of claim 50, wherein the cations are selected from the group consisting of calcium ions, barium ions, magnesium ions and sodium ions.
52. The power plant of claim 51, wherein the cations are Ca++ and the carbonated species is CaCO3.
53. The power plant of any one of claims 38 to 50, wherein the carbonated species comprise precipitates.
54. The power plant of claim 53, wherein the precipitates are separable from the solution.
55. The power plant of claim 53, wherein the precipitates comprise stable solid products.
56. The power plant of claim 53, wherein the carbonated species consist of precipitates.
57. The power plant of any one of claims 38 to 56, comprising a scrubber for removing additional contaminants the exhaust gas.
58. The power plant of claim 57, wherein the additional contaminants removed by the scrubber are selected from the group consisting of ash, NO x and SO2.
59. The power plant of claim 57 or 58, wherein the scrubber is located upstream of the means for contacting the aqueous liquid phase with the cooled exhaust gas and the biological catalyzing means.
60. The power plant of any one of claims 38 to 59, wherein the means for cooling the exhaust gas is configured to cool the exhaust gas to a temperature sufficient to maintain a desired catalytic effect of the carbonic anhydrase or the analog thereof.
61. The power plant of claim 60, wherein the temperature to which the exhaust gas is cooled avoids a given denaturing of free carbonic anhydrase.
62. The power plant of claim 60, wherein the temperature to which the exhaust gas is cooled avoids a given denaturing of immobilized carbonic anhydrase.
63. The power plant of claim 60, wherein the temperature to which the exhaust gas is cooled avoids a given denaturing of free and immobilized carbonic anhydrase.
64. The power plant of any one of claims 38 to 63, comprising means for recycling heat removed from the means for cooling the exhaust gas into the means for converting the heat into energy.
65. The power plant of any one of claims 38 to 64, wherein the bioreactor is configured such that the contacting of the aqueous liquid phase with the cooled exhaust gas is performed counter-currently.
66. The power plant of any one of claims 38 to 65, wherein the fossil fuel comprises coal.
67. The power plant of any one of claims 38 to 66, wherein the exhaust gas has a CO2 concentration between 0.5% and 12%.
68. The power plant of any one of claims 38 to 67, wherein the solution containing hydrogen ions and carbonate ions is treated to remove the carbonated species and is subsequently recycled back to be used as the aqueous liquid phase.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2499264A CA2499264C (en) | 2002-09-27 | 2003-09-29 | A process and a plant for recycling carbon dioxide emissions from power plants into useful carbonated species |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002405635A CA2405635A1 (en) | 2002-09-27 | 2002-09-27 | A process and a plant for the production of useful carbonated species and for the recycling of carbon dioxide emissions from power plants |
| CA2,405,635 | 2002-09-27 | ||
| CA2499264A CA2499264C (en) | 2002-09-27 | 2003-09-29 | A process and a plant for recycling carbon dioxide emissions from power plants into useful carbonated species |
| PCT/CA2003/001496 WO2004028667A1 (en) | 2002-09-27 | 2003-09-29 | A process and a plant for recycling carbon dioxide emissions from power plants into useful carbonated species |
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| CA2499264A1 CA2499264A1 (en) | 2004-04-08 |
| CA2499264C true CA2499264C (en) | 2011-04-12 |
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