KR101686574B1 - Carbon dioxide capture system using a Alcohol converting apparatus - Google Patents

Abstract

The present invention relates to a carbon dioxide capturing system using an alcohol conversion apparatus, which can capture carbon dioxide by using a method different from conventional methods. A carbon dioxide capturing system using an alcohol conversion apparatus according to an embodiment of the present invention comprises: a pretreatment part which removes nitrogen oxides (NOx) and sulfur oxides (SOx) from flue gas; a cooling chamber which is formed to include a first coolant so as to cool the flue gas, discharged from the pretreatment part, to a preset temperature or lower; a tank which dissolves carbon dioxide by cooling the flue gas discharged from the cooling chamber until a preset dissolution condition is reached; a conversion chamber which includes a lighting means configured to convert the dissolved carbon dioxide into methanol by radiating light onto a filled photocatalyst part when water in which the carbon dioxide has been dissolved is introduced; a treatment part which includes a filter unit and a distillation and cooling part so as to separately collect the photocatalyst and methanol when the converted liquid is introduced from the conversion chamber; and an elimination unit which includes activated carbon so as to purify the converted liquid from which the methanol has been collected, and which is formed to return the purified, converted liquid to the tank. The tank includes a branch part configured to move a part of the flue gas, primarily cooled via the cooling chamber, to the tank accommodating a second coolant to the extent that satisfies the preset dissolution condition and to store the remainder of the flue gas in a storage unit and then move the remainder to the tank when the dissolution condition is satisfied.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a carbon dioxide capture system using an alcohol conversion apparatus,

One embodiment of the present invention relates to a system for collecting carbon dioxide using an apparatus for converting carbon dioxide to alcohol.

Carbon dioxide has served as a greenhouse to maintain the current civilized world. However, the surge in energy consumption due to population growth and industrial development is expected to lead to an unprecedented increase in carbon dioxide, which will exceed the atmospheric carbon dioxide concentration of 400 ppm. This is caused by global warming, glacier shrinkage, sea level rise, and severe natural disasters such as heavy rains or droughts. This is a phenomenon to find equilibrium points. However, if the phenomenon exceeds the critical point, it will be impossible to reverse it again. This suggests that the decline of Arctic ice is accelerating.

The world, including the European Union, is trying to stabilize the CO2 concentration at 500 ppm. We have been making various efforts such as energy efficiency and alternative energy development by reducing carbon dioxide, but the increase of carbon dioxide is continuing. This is because the consumption of energy continues to increase with the development of the emerging countries and the population increase. With increasing energy consumption, the use of fossil fuels is expected to be used for more than the next few decades.

This is because it can not replace fossil fuels with renewable energy such as solar cells and wind power. This is because these renewable energies can not replace existing fossil fuels in terms of energy triple sounds (density, storage, transport). Therefore, the post-treatment technology for the generated carbon dioxide is needed, but an effective method has not been proposed. In spite of many environmentalists' problems, storage technology has been recognized as the most realistic post-production technology, and it has been recognized that the clean development mechanism (CDM) project of these processing technologies is recognized. . The treatment of carbon is thought to be more effective in treating carbon (carbon dioxide) through the carbon cycle through the natural CO2 cycle.

With the introduction of mandatory greenhouse gas emission reduction quotas through enforcement of the UNFCCC and penalties such as fines, interest in the green technology industry has been increasing worldwide and research and development has been actively carried out to realize this. Research has been focused mainly on CCS, which collects carbon dioxide, which is a representative greenhouse gas emitted in large quantities in industrial processes, as waste and reclaims it on the seabed. However, recent studies on CCU technology for recycling carbon dioxide I am getting new interest.

CCU technology uses carbon dioxide as a useful resource rather than simply a dumped substance and converts it into value-added chemicals with high added value. It solves environmental problems through reduction of greenhouse gases, The abundance of carbon dioxide is used as a carbon source and, after use, it is discharged into the atmosphere in the form of carbon dioxide again, meaning that it can be found in terms of recycling of a sustainable carbon source. In addition, since the addition of high-value-added carbon compounds after conversion is expected to generate additional profits, the possibility is gradually being recognized.

Therefore, more efficient carbon capture and utilization technology can be considered, which not only captures carbon dioxide but also can be recycled and used as fuel.

Korean Patent Publication No. 2015-0010914 (Jan. 29, 2015)

An object of the present invention is to provide a carbon dioxide capture system having an alcohol conversion device capable of capturing carbon dioxide by a method other than the conventional method.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a carbon dioxide capture system having an alcohol conversion device according to an embodiment of the present invention includes a pretreatment unit for removing NOx and sulfur oxides from an exhaust gas from an exhaust gas, A cooling chamber formed with a first cooling water for cooling the exhaust gas discharged from the pre-processing unit to a predetermined temperature or lower; and a cooling chamber for cooling the exhaust gas discharged from the cooling chamber until a preset dissolution condition is reached, A conversion chamber having a tank for dissolving carbon dioxide and lighting means for converting dissolved carbon dioxide into methanol by irradiating light to the photocatalyst portion charged when the dissolved water in which the carbon dioxide is dissolved is introduced; , A filter portion and a distillation and cooling portion for separating and recovering the photocatalyst and methanol And a removal section including activated carbon so as to stabilize the conversion liquid from which the methanol is recovered, and a removal section formed to re-flow the stabilized conversion liquid into the tank, wherein the tank is provided with the cooling chamber A portion of the first cooled flue gas is transferred to the tank containing the second cooling water to a range satisfying a predetermined dissolution condition and the remaining flue gas is stored in the storage portion and is formed to move to the tank when the dissolution condition is satisfied As shown in Fig.

According to an example of the present invention, the storage unit may be arranged to be locked by the first cooling water.

According to one example of the present invention, the dissolution conditions may be a pressure of 1.5 MPa to 3.5 MPa and a temperature of 2 to 5 占 폚.

According to one embodiment of the present invention, the second cooling water further comprises sodium hydroxide, and the dissolving water introduced into the conversion chamber is at least one member selected from the group consisting of propanol, Na ₂ S and Na ₂ SO ₃ And an alcohol conversion device comprising the alcohol conversion device.

According to one example of the present invention, the photocatalyst unit comprises CUO, activated carbon and TiO ₂ In a predetermined ratio.

The carbon dioxide capture system having the alcohol conversion apparatus according to at least one embodiment of the present invention configured as described above can convert energy from carbon dioxide to methanol in the exhaust gas.

Also, since the absorption rate of carbon dioxide is high, it can be widely used in a process of collecting carbon dioxide contained in flue gas discharged from a boiler of a thermal power plant, a steel factory, a cement factory, or an industrial plant, and can contribute to environmental protection.

1 is a conceptual diagram showing a methanol conversion system according to an embodiment of the present invention;
2 is a flowchart of a carbon dioxide capture system having an alcohol conversion device according to an embodiment of the present invention;
3 is a view illustrating a photocatalytic reaction process according to an embodiment of the present invention.
4 is a view illustrating a process of methanol generation according to an embodiment of the present invention.

Hereinafter, a carbon dioxide capture system having an alcohol conversion device according to the present invention will be described in detail with reference to the drawings. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the present specification, the same or similar reference numerals are given to different embodiments in the same or similar configurations. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

1 is a conceptual diagram showing an alcohol conversion system 100 according to an embodiment of the present invention.

1, the alcohol conversion system 100 includes a pretreatment unit 120, a cooling chamber 130, a tank 140, a conversion chamber 150, a processing unit 160, a methanol storage unit 170, (180).

The pretreatment unit 120 removes nitric oxide (NOx) and sulfur oxides (SOx) from the exhaust gas from the exhaust source 110 after combustion. The exhaust gas is mixed with primary fine dust and secondary fine dust in addition to CO ₂ , and these fine dusts are removed from the cooling chamber and the tank 140 in which the primary cooling and the secondary cooling are performed. Here, the flue gas may be flue gas discharged from a boiler of a thermal power plant, a steel plant, a cement plant, or an industrial plant.

The exhaust gas from which NOx and sulfur oxides (SOx) have been removed through the pretreatment unit 120 moves to the cooling chamber 130. The cooling chamber 130 uses the first cooling water to keep the internal temperature below a certain level. The cooling chamber 130 allows the flue-gas to be below 60 ° C, and carbon dioxide in the flue-gas is hardly dissolved during this process.

The exhaust gas cooled from the cooling chamber 130 is transferred to the tank 140 and the storage portion 141 via the branch portion 131, respectively. The exhaust gas is first introduced into the tank 140. If the dissolution conditions are not satisfied due to the inflow of the exhaust gas, the exhaust gas is prevented from flowing into the tank 140, and the exhaust gas is stored in the storage unit 141. [ The storage unit 141 has a filter for removing fine dust from the exhaust gas. Further, the storage part 141 is arranged to be locked by the first cooling water of the cooling chamber 130. [ Thus, the temperature of the exhaust gas stored in the storage unit 141 can be further lowered. That is, since the flue gas is stored in the storage unit 141, when the flue gas flows into the tank 140 from the storage unit 141, the amount of the flue gas flowing into the tank 140 is increased .

For example, the branching unit 131 may include a 3-way valve, and the passage of the flue gas may be opened or closed by sensing a dissolution condition in the tank 140.

The tank 140 uses the second cooling water to cool the flue gas to dissolve the carbon dioxide. At this time, the dissolution conditions are a pressure of 1.5 MPa to 3.5 MPa and a temperature of 2 to 5 캜. The tank 140 is formed so as to satisfy the above dissolution conditions. Due to the inflow of the flue gas, the inflow of the flue gas is blocked if any of the above-mentioned dissolution conditions is exceeded. Under the above conditions, the dissolution rate of carbon dioxide reaches about 70%.

At higher temperatures, the dissolution efficiency of carbon dioxide drops sharply. That is, when the temperature inside the tank 140 is 5 to 7 占 폚, the dissolution rate of carbon dioxide is 65% or less. Also, at lower temperatures, the required power is high and the efficiency is low. The dissolution rate of carbon dioxide at -1 DEG C is only 70.35%.

Further, when the tank 140 is designed to have a pressure of 3.5 MPa or more, a large amount of cost is required for manufacturing and maintaining the tank 140, and the dissolution rate of the carbon dioxide does not greatly increase even if the pressure is high. That is, even at a pressure of 3.6 MPa, the dissolution rate of carbon dioxide is only 70.2% under the same temperature condition. Further, at 1.4 MPa, which is lower than 1.5 MPa, the dissolution rate of carbon dioxide is remarkably reduced to 67%.

The addition of sodium hydroxide to the second cooling water further increased the methanol conversion efficiency of the carbon dioxide. When sodium hydroxide is added, the solubility of carbon dioxide is increased, and the added OH ^- is used as an electron donor to slow the recombination reaction of electron-hole.

The dissolved water in which the flue gas is dissolved flows into the conversion chamber 150. The inside of the switching chamber 150 is filled with a photocatalyst 151. When light is irradiated to the photocatalyst unit 151 using the illuminating unit 152, the carbon dioxide dissolved in the dissolving water is converted to methanol. At this time, the illuminating means can emit visible light or emit ultraviolet light.

The photocatalyst portion 151 may be formed in various shapes. For example, metal or metal oxide may be used as a promoter. For example, it can be produced in a complex form by using hydrothermal synthesis method, sol-gel method, microwave method, ultrasonic method, etc. in the state of containing activated carbon, titanium dioxide and copper oxide.

That is, the photocatalyst is TiO _2, activated carbon -TiO _2, graphene -TiO _2, activated carbon CuO- -TiO _2, WO ₃ - and the like can be used active carbon -TiO _2. Among them, the production efficiency (Vo / Vol) is 1.5 or less, 1.5 to 2.7, 2.5 to 3.0, 4.0 to 4.5 or 3.5 to 4.2, respectively, and the production efficiency is highest when CuO-activated carbon-TiO ₂ is used as a photocatalyst . TiO ₂ doped with CuO and WO ₃ increases the conversion efficiency of carbon dioxide to methanol. Also, activated carbon and TiO ₂ Is combined TiO ₂ The reduction efficiency of carbon dioxide is increased.

The alcohol-based electron donor may be added to the dissolving water introduced into the conversion chamber 150. [ For example, the addition of propanol can lead to a rapid oxidation of water, thereby increasing the reduction efficiency of carbon dioxide. Also, at least one of the group consisting of Na ₂ S and Na ₂ SO ₃ may be used as a sacrificial agent or a scavenger.

When the conversion takes place, the methanol will be in a gaseous or liquid state. Since the conversion liquid contains a part of methanol, the conversion liquid and the conversion gas are transferred to the processing section 160. The processing unit 160 includes a filter unit 161 and a distillation and cooling unit 162. The filter unit 161 is used to recover the photocatalyst contained in the conversion liquid. The distillation and cooling unit 162 is used to recover methanol from the conversion liquid.

The conversion liquid from which the methanol is recovered is made to settle through the removal unit 180 formed with activated carbon. The stationary conversion liquid flows back into the tank 140.

As described above in relation to methanol in the alcohol conversion system, ethanol may be produced when the alcohol is converted, and some of the methanol may be converted into ethanol when the conversion time exceeds the predetermined conversion time in the conversion chamber.

2 is a flowchart of a carbon dioxide capture method using an alcohol conversion system 100 according to an embodiment of the present invention.

Referring to FIG. 2, the carbon dioxide capture method using the alcohol conversion system 100 includes a first cooling step, a second cooling and dissolving step, a methanol conversion step, a methanol recovery step, and a tank re-inflow step.

The primary cooling step

In the first cooling step, the exhaust gas flowing in the pre-treatment unit 120 is cooled to 60 ° C or lower. The pretreatment unit 120 removes nitric oxide (NOx) and sulfur oxides (SOx) from the exhaust gas after combustion from the emission source. The exhaust gas is mixed with primary fine dust and secondary fine dust in addition to CO ₂ , and these fine dusts are removed from the cooling chamber and the tank 140 in which the primary cooling and the secondary cooling are performed. The exhaust gas from which NOx and sulfur oxides (SOx) have been removed through the pretreatment unit 120 moves to the cooling chamber 130. The cooling chamber 130 uses the first cooling water to keep the internal temperature below a certain level. The cooling chamber 130 allows the flue-gas to be below 60 ° C, and carbon dioxide in the flue-gas is hardly dissolved during this process.

Thus, in the first cooling step, the exhaust gas flows into the cooling chamber provided with the first cooling water so that the exhaust gas becomes 60 DEG C or less, and is first cooled.

Secondary cooling and dissolution steps

In the second cooling and dissolving step, the exhaust gas is cooled to a predetermined temperature or less to dissolve the carbon dioxide in the dissolving water. That is, a part of the flue gas that has been primarily cooled using the branching unit is moved to the tank 140 containing the second cooling water to a range satisfying predetermined dissolution conditions, the remaining flue gas is stored in the storage unit 141, To the tank (140).

This will be described in more detail as follows.

The exhaust gas cooled from the cooling chamber 130 is transferred to the tank 140 and the storage portion 141 via the branch portion 131, respectively. The exhaust gas is first introduced into the tank 140. If the dissolution conditions are not satisfied due to the inflow of the exhaust gas, the exhaust gas is prevented from flowing into the tank 140, and the exhaust gas is stored in the storage unit 141. [ The storage unit 141 has a filter for removing fine dust from the exhaust gas. Further, the storage part 141 is arranged to be locked by the first cooling water of the cooling chamber 130. [ Thus, the temperature of the exhaust gas stored in the storage unit 141 can be further lowered. That is, since the flue gas is stored in the storage unit 141, when the flue gas flows into the tank 140 from the storage unit 141, the amount of the flue gas flowing into the tank 140 is increased .

The tank 140 uses the second cooling water to cool the flue gas to dissolve the carbon dioxide. At this time, the dissolution conditions are a pressure of 1.5 MPa to 3.5 MPa and a temperature of 2 to 5 캜. The tank 140 is formed so as to satisfy the above dissolution conditions. Due to the inflow of the flue gas, the inflow of the flue gas is blocked if any of the above-mentioned dissolution conditions is exceeded. Under the above conditions, the dissolution rate of carbon dioxide reaches about 70%.

At higher temperatures, the dissolution efficiency of carbon dioxide drops sharply. That is, when the temperature inside the tank 140 is 3 to 5 占 폚, the dissolution rate of carbon dioxide is 65% or less. Also, at lower temperatures, the required power is high and the efficiency is low. And the dissolution rate of carbon dioxide at-1 캜 is only 70.35%.

Further, when the tank 140 is designed to have a pressure of 3.5 MPa or more, a large amount of cost is required for manufacturing and maintaining the tank 140, and the dissolution rate of the carbon dioxide does not greatly increase even if the pressure is high. That is, even at a pressure of 3.6 MPa, the dissolution rate of carbon dioxide is only 70.2% under the same temperature condition. Further, at 1.4 MPa, which is lower than 1.5 MPa, the dissolution rate of carbon dioxide is remarkably reduced to 67%.

The addition of sodium hydroxide to the second cooling water further increased the methanol conversion efficiency of the carbon dioxide. When sodium hydroxide is added, the solubility of carbon dioxide is increased, and the added OH ^- is used as an electron donor to slow the recombination reaction of electron-hole.

Methanol conversion step

In the methanol conversion step, when the dissolved water dissolved in the exhaust gas flows into the conversion chamber 150, light is irradiated to the photocatalyst unit 151 filled in the conversion chamber 150, and carbon dioxide dissolved in the dissolution water is converted into methanol .

At this time, the photocatalyst is TiO _2, activated carbon -TiO _2, graphene -TiO _2, activated carbon CuO- -TiO _2, WO ₃ - and the like can be used active carbon -TiO _2. Among them, the production efficiency (Vo / Vol) is 1.5 or less, 1.5 to 2.7, 2.5 to 3.0, 4.0 to 4.5 or 3.5 to 4.2, respectively, and the production efficiency is highest when CuO-activated carbon-TiO ₂ is used as a photocatalyst . TiO ₂ doped with CuO and WO ₃ increases the conversion efficiency of carbon dioxide to methanol. Also, activated carbon and TiO ₂ Is combined TiO ₂ The reduction efficiency of carbon dioxide is increased.

The alcohol-based electron donor may be added to the dissolving water introduced into the conversion chamber 150. [ For example, the addition of propanol can lead to a rapid oxidation of water, thereby increasing the reduction efficiency of carbon dioxide.

Methanol recovery step

In the methanol recovery step, when the conversion liquid containing methanol flows into the processing unit 160, the photocatalyst contained in the conversion liquid is recovered using the filter unit, and the conversion liquid is distilled and cooled to recover the methanol. When the conversion of methanol occurs, the methanol is present in a gas or liquid state. Since the conversion liquid contains a part of methanol, the conversion liquid and the conversion gas are transferred to the processing section 160. The treatment unit 160 includes a filter unit, a distillation and cooling unit, and uses the filter unit to recover the photocatalyst contained in the conversion liquid. Methanol is recovered from the conversion liquid using a distillation and cooling section. The recovered methanol is stored in the methanol recovery tank 140 (170).

Tank reintroduction phase

In the tank reintroduction step, the converted liquid from which the methanol is recovered is fixed through the remover 180 containing activated carbon, and then reintroduced into the tank 140.

FIG. 3 is a view illustrating a photocatalytic reaction process in the conversion chamber 150 according to an embodiment of the present invention.

Photocatalyst is a substance that functions as a catalyst by using light energy. The reaction mechanism is as follows.

That is, the photocatalyst includes a common band and a conduction band having an energy gap between each band. When the photocatalyst absorbs sufficient light energy to overcome this band gap, electrons are excited from the common band to the conduction band, Accordingly, a hole having an electron in an empty state is generated in the common band.

When electrons and holes are generated in the photocatalyst, they generate photocatalytic reactions such as hydrogen generation and oxidation of various organic materials. TiO ₂ is the most widely used photocatalyst.

When titanium is exposed to air, it readily reacts with oxygen to be oxidized to form titanium dioxide (TiO ₂ ) in the form of a film. The properties of titanium dioxide have a good condition for being used as a photocatalyst.

When titanium is exposed to air, it readily reacts with oxygen to be oxidized to form titanium dioxide (TiO ₂ ) in the form of a film. The properties of titanium dioxide have a good condition for being used as a photocatalyst.

In other words, it absorbs light and oxidizes other substances and has a very high oxidizing power. It is not soluble in almost all solvents such as acids, bases or aqueous solutions because of its large negative power.

It is harmless to the environment and human body because it does not react with biological reaction, and it is a particularly stable substance.

However, since the band gap of titanium dioxide, which is widely used as such a photocatalyst, is 3.0-3.2 eV, ultraviolet (u.v) light region shorter than 388 nm is required to overcome this band gap.

4 is a view illustrating a process of methanol generation in the switching chamber 150 according to an embodiment of the present invention.

When the titanium dioxide photocatalyst doped with the transition metal in the conversion chamber 150 reacts with the H ₂ O (water) in the exhaust gas and the light emitted from the illuminating means 152, O ₂ (oxygen) and 4H ⁺ (Hydrogen) radical, and 4e ^- (hole).

2H2O? O2 (g) + 4H (aq.) + 4e- [Reaction Scheme 1]

CO2 (aq.) + E- CO2- (aq.) [Reaction Scheme 2]

Also. As shown in Scheme 2, CO ₂ (carbon dioxide) in the flue gas reacts with the e ^- (hole) generated in Scheme 1 to generate CO ₂ ^- .

CO ₂ + 2H ₂ O? CH ₃ OH + 3 / 2O ₂ [Reaction Scheme 3]

Further, the 4H ⁺ (hydrogen) radical generated in the above reaction formula 1 and the CO ₂ ^- (carbon dioxide hole) generated in the reaction formula 2 act as a catalytic reaction, so that CH ₃ OH (methanol) and 3/3/2 O ₂ It reacts to the process of creation.

 The methanol generated inside the conversion chamber 150 exists in a gas or state and is discharged to the processing unit 160 through an exhaust pipe. The methanol is distilled and cooled by the treatment section 160 installed at the tip of the discharge pipe and stored in the methanol storage section 170.

The carbon dioxide capture system having the above-described alcohol conversion device can be applied to a configuration and a method of the above-described embodiments in a limited manner, but the embodiments can be applied to all or some of the embodiments May be selectively combined.

Claims (5)

A pretreatment unit for removing oxides of nitrogen (NOx) and sulfur oxides (SOx) from the flue gas from the flue gas;
A cooling chamber formed with a first cooling water to cool the exhaust gas discharged from the pre-processing unit to a predetermined temperature or lower;
A tank for cooling the exhaust gas discharged from the cooling chamber until the predetermined dissolution condition is reached to dissolve the carbon dioxide;
A conversion chamber having illumination means for irradiating light to the filled photocatalyst portion to convert the dissolved carbon dioxide to methanol when the dissolved water in which the carbon dioxide is dissolved is introduced from the tank;
A processing unit having a filter unit and a distillation and cooling unit for separating and recovering the photocatalyst and methanol when the conversion liquid flows from the conversion chamber; And
And a removing unit including a removing unit including activated carbon so as to purify the conversion liquid from which the methanol is recovered, the removing unit being configured to re-flow the purified conversion liquid into the tank,
The tank may comprise:
A part of the flue gas that has been primarily cooled through the cooling chamber is moved to the tank containing the second cooling water to a range satisfying a predetermined dissolution condition and the remaining flue gas is stored in the storage part and then, And a branching portion formed so as to move the carbon dioxide trapping device.
The method according to claim 1,
And the storage unit is arranged to be locked by the first cooling water.
3. The method of claim 2,
Wherein the dissolution condition is a pressure of 1.5 MPa to 3.5 MPa and a temperature of 2 to 5 ° C.
The method according to claim 1,
Wherein the second cooling water further comprises sodium hydroxide,
Wherein the dissolving water introduced into the conversion chamber includes propanol. ≪ Desc / Clms Page number 20 >
The method according to claim 1,
Wherein the photocatalyst unit comprises CuO, activated carbon, and TiO ₂ in a predetermined ratio.

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