TWI421123B - Method of capturing carbon dioxide - Google Patents

Description

Method of capturing carbon dioxide

This invention relates to a method of capturing carbon dioxide, and more particularly to a method suitable for capturing carbon dioxide in a stack exhaust gas produced by a combustion furnace.

After the steam engine opened the modern industrial revolution, industrial technology has made great progress. In order to meet the various needs of a growing population, a wide variety of manufacturing plants have emerged, and with the mass production, a large amount of exhaust gas (chimney exhaust) is discharged through the factory chimney.

In order to avoid the above-mentioned large amount of exhaust gas being discharged into the atmosphere, it has a negative impact on the atmospheric environment. Therefore, it is necessary to remove the above-mentioned harmful gas before discharging the above-mentioned large amount of exhaust gas into the atmosphere, and the most important harmful gas therein contains carbon dioxide. Among the exhaust gases produced in the manufacturing process, carbon dioxide occupies a considerable amount, and since carbon dioxide is a greenhouse gas, if it is discharged into the atmosphere without treatment, it will promote the deterioration of the greenhouse effect in the atmospheric environment.

The technology used to capture and store carbon dioxide from other gases in a variety of processes is collectively referred to as Carbon Capture and Storage (CCS). CCS technology is generally divided into the following four methods. The first type is a chemical absorption method in which a specific chemical absorbent is used depending on the composition of the exhaust gas, whereby the chemical absorbent absorbs carbon dioxide in the exhaust gas. The second type is the physical adsorption method. In the physical adsorption method, it is mainly divided into two types, one is Pressure Swing Adsorption (PSA), and the other is Temperature Swing Adsorption (TSA). The third type is Cryogenic. Since carbon dioxide can be condensed at -56.6 ° C and 7.4 atm and separated from nitrogen (N ₂ ), carbon dioxide can be captured by this characteristic. The last one is Membrane Diffusion, in which the thin film method has the advantage of saving energy, but this method belongs to a more advanced technology and is still in the development stage.

In foreign steel mills, some steel mills have studied the capture of carbon dioxide in blast furnace exhaust (Blast Furnace Gas; BFG). For example, Japan's Nippon Steel Corporation (NSC) used chemical absorption to capture carbon dioxide in BFG and separate it from other gases. However, there is no relevant research on the capture of carbon dioxide in the exhaust gas of the stove of the hot stove. In BFG, the main component is flammable gas, and in the exhaust gas of the hot stove chimney, the main component is the chimney exhaust of the general combustion furnace. Since the composition of the BFG and the hot air stove chimney are significantly different, and their characteristics are completely different, it is impossible to capture the carbon dioxide in the exhaust gas of the hot stove chimney by referring to the carbon dioxide capture method of BFG.

In the Ultra Low CO ₂ Steelmaking (ULCOS) conducted by the European Union, Vacuum Pressure Swing Adsorption (VPSA) is used to capture carbon dioxide for BFG. However, the adsorption method is generally only applicable to chimney exhaust gas with a low carbon dioxide concentration. For the capture of carbon dioxide in the exhaust gas of BFG or hot stove chimney, a chemical absorption method should be used.

In addition, South Korea's POSCO steel mill is developing technology to use ammonia (Ammonia) to capture carbon dioxide. However, the ammonia in this technology is easy to dissipate, so it remains to be seen whether it will be commercially viable in the future.

Furthermore, there are other related studies on the capture of carbon dioxide. For example, in U.S. Patent No. 7,056,482, Cansolv Technologies Inc. of Canada proposes the use of Tertiary Amine as an absorbent to capture carbon dioxide from specific exhaust gases and separate it from other gases. . In U.S. Patent No. 7,288,136, the Department of Energy (DOE) proposes to drive amines into porous materials, thereby increasing the content of amines in the porous material, thereby increasing the trapping of the porous material. The effect of carbon dioxide.

However, the techniques described in the above two patents are not applicable to the capture of carbon dioxide in the exhaust gas of a hot stove chimney. Therefore, it is necessary to propose a new carbon dioxide capture method suitable for the exhaust gas of a hot stove.

Accordingly, it is an object of the present invention to provide a method of capturing carbon dioxide which is suitable for capturing carbon dioxide in a chimney exhaust gas produced by a combustion furnace by contacting a primary amine solution with a chimney exhaust gas and controlling the flow of the chimney exhaust gas, chimney exhaust gas. The temperature and the flow rate of the primary amine solution can effectively increase the capture efficiency of carbon dioxide in the chimney exhaust gas to over 90%.

According to an embodiment of the present invention, a method for capturing carbon dioxide is provided, which is suitable for capturing carbon dioxide in a chimney exhaust gas generated by a combustion furnace, wherein the chimney exhaust gas contains a plurality of components, wherein the components are carbon dioxide water and sulfur oxides. (SO _X ), nitrogen oxides (NO _X ), unavoidable impurities, and the remainder (also referred to as residues) composed of nitrogen. The method for capturing carbon dioxide comprises: performing a pre-process for removing water, sulfur oxides, nitrogen oxides or unavoidable impurities in the chimney exhaust gas; performing a chimney exhaust step at 10 cubic meters per hour (m ³ /hr) Providing the above-mentioned chimney exhaust gas to a first predetermined flow rate of 11 cubic meters per hour, wherein the chimney exhaust gas temperature is 30 ° C to 40 ° C; performing a carbon dioxide absorption step to provide a primary amine solution containing water and a primary amine at a second predetermined flow rate Achieving carbon dioxide in the chimney exhaust gas by a primary amine, wherein a primary amine solution is provided at a second predetermined flow rate to provide 60 kg to 70 kg of primary amine per hour; and a primary amine regeneration step is performed, thereby allowing the primary amine to be absorbed Carbon dioxide is detached.

The invention has the advantages of effectively increasing the capture efficiency of carbon dioxide in the chimney exhaust gas by contacting the primary amine solution with the chimney exhaust gas and controlling the parameters of the primary amine solution and the chimney exhaust gas. Among them, in a specific embodiment, the primary amine as a carbon dioxide absorber can release the carbon dioxide absorbed by heating, so that the primary amine solution can be directly regenerated in the field. In addition, since the primary amine solution is not easily dissipated, it is not necessary to frequently replenish the carbon dioxide absorbent, and therefore, in a particular embodiment, the apparatus employing the method of the present invention can be operated stably and continuously, so that the apparatus employing the method of the present invention is more Have a competitive advantage.

Please refer to FIG. 1 , which is a flow chart showing a method for capturing carbon dioxide according to an embodiment of the present invention, wherein the method 100 for capturing carbon dioxide is suitable for capturing chimney exhaust gas generated by a combustion furnace such as a hot blast stove. carbon dioxide. In the above-mentioned chimney exhaust gas, it contains a plurality of components, which are carbon dioxide, water, sulfur oxides, nitrogen oxides, unavoidable impurities, and other parts composed of nitrogen. In certain embodiments of the chimney component comprises a plurality of exhaust gas were: 26 ~ 29 vol% of carbon dioxide, 14 ~ 16 vol% water, 0.003 ~ 0.004 vol% of the sulfur oxides (SO _X) and nitrogen oxide (NO _X ), unavoidable impurities, and other parts composed of nitrogen.

However, the chimney exhaust gas suitable for use in the carbon dioxide capture method 100 of the present invention is not limited only to the chimney exhaust gas produced by the hot blast stove, and the method of the present invention is more applicable to the carbon dioxide in the chimney exhaust gas produced by other combustion furnaces. Capture.

The method 100 of capturing carbon dioxide begins with a pre-process 102. In the pre-process 102, it is mainly used to remove water, sulfur oxides, nitrogen oxides or unavoidable impurities in the chimney exhaust gas. In a particular embodiment, the chimney waste gases are removed prior to the process 102 in the sulfur oxide containing sulfur dioxide (SO _2).

After completing the previous process 102 described above, the method 100 of capturing carbon dioxide proceeds to provide a chimney exhaust step 104. In the provision of the chimney exhaust step 104, the chimney exhaust after the removal of water, sulfur oxides, nitrogen oxides or unavoidable impurities by the pre-process 102 is provided at a first predetermined flow rate. The first predetermined flow rate is 10 cubic meters per hour to 11 cubic meters per hour. Further, the temperature of the stack exhaust gas is controlled to be between 30 ° C and 40 ° C, thereby promoting the absorption of the carbon dioxide absorber. In the present invention, however, the carbon dioxide absorber is a primary amine.

The method 100 of capturing carbon dioxide is followed by a carbon dioxide absorption step 106 to provide a primary amine solution at a second predetermined flow rate. Since the primary amine is corrosive, in order to avoid primary amine corrosion equipment (e.g., absorption towers), it is desirable to dilute the primary amine with water to form the primary amine solution described above. In the step of absorbing carbon dioxide 106, the carbon dioxide in the chimney exhaust gas is mainly absorbed by the primary amine contained in the primary amine solution. In order to efficiently absorb carbon dioxide in the chimney exhaust gas, wherein the first-order amine solution is provided at the second predetermined flow rate described above, 60 kg to 70 kg of primary amine can be supplied per hour, thereby capturing the carbon dioxide capture efficiency in the chimney exhaust gas. More than 90%.

In a particular embodiment, the step of providing chimney exhaust gas 104 further includes providing chimney exhaust after treatment with a pre-process 102 by a bottom of an absorber. Further, in this embodiment, the step of absorbing carbon dioxide 106 further comprises spraying a primary amine solution from the top of the absorption tower. Since the primary amine solution is supplied to the absorption tower by spraying, the surface area of the primary amine solution can be increased, thereby increasing the contact probability of the chimney exhaust gas with the primary amine solution. Since the primary amine solution is in a liquid state and the chimney exhaust gas is in a gaseous state, by providing the chimney exhaust gas and the primary amine solution respectively from the bottom and the top of the absorption tower, the probability of contact between the chimney exhaust gas and the primary amine solution can be increased, which is helpful for upgrading. The capture efficiency of carbon dioxide.

In addition, in order to increase the contact probability of the chimney exhaust gas in the absorption tower and the primary amine solution, a structure for slowing down the gas rising rate may be disposed at the bottom of the absorption tower, thereby avoiding a channel in the absorption tower where the chimney exhaust gas can directly rise. Since the structure of the above absorption tower is well known to those of ordinary skill in the art, it will not be described in detail.

In a particular embodiment, the primary amine contained in the primary amine solution is monoethanolamine (MEA). Further, in a particular embodiment, the above primary amine solution preferably comprises 20% by weight of primary amine in weight percent (wt%).

Finally, the method 100 of capturing carbon dioxide is subjected to a primary amine regeneration step 108 whereby the carbon dioxide absorbed by the primary amine described above is removed from the primary amine. In a particular embodiment, the above-described primary amine solution that absorbs carbon dioxide can be heated using a heating device such as an electric heater. The heat provided by the heating device is used to remove the carbon dioxide absorbed by the primary amine from the primary amine to facilitate recycling of the primary amine. In order to satisfy the efficiency of the above-mentioned primary amine for absorbing carbon dioxide, the heating device needs to supply heat to the absorbed amine monoamine solution at a specific power. Therefore, the heating temperature of the heating device is preferably set at 100 ° C to 105 ° C. between.

In the above embodiment in which the primary amine solution is heated by the heating means, in order to be able to regenerate the primary amine more efficiently, the primary amine regeneration step 108 further comprises spraying the primary amine solution from the top of a stripping column via the carbon dioxide absorption step 106 described above. And the heating device is placed at the bottom of the stripper. Since the structure of the stripper is well known to those of ordinary skill in the art, it will not be described in detail.

Moreover, in the present embodiment, the method 100 of capturing carbon dioxide further includes performing a carbon dioxide storage step 110 to store the carbon dioxide obtained by the treatment of the primary amine regeneration step 108 described above into a particular vessel.

Moreover, in the present embodiment, the method 100 of capturing carbon dioxide further comprises performing a recycling step 112 to transfer the primary amine solution obtained by the treatment of the primary amine regeneration step 108 via the transfer line to the absorption as described above. In the column, a carbon dioxide absorption step 106 is performed.

Please refer to Table 1 below, wherein Table 1 is a comparison of three embodiments of the method 100 for capturing carbon dioxide using the present invention. The content of the components of the chimney exhaust gas is 28.2 vol% carbon dioxide, 15.4 vol% water, 0.0035 vol% sulfur oxides and nitrogen oxides (NO _X ), unavoidable impurities, and nitrogen gas. other parts.

According to the above Table 1, the system using the method for capturing carbon dioxide 100 of the present invention can capture more than 100 kg of carbon dioxide per day if it is operated for 24 hours per day. Moreover, the capture efficiency of the carbon dioxide capture method 100 of the present invention is greater than 90% when calculated by weight. Furthermore, after a one-year actual trial run, it was found that the system using the carbon dioxide capture method 100 of the present invention not only has excellent stability, but also can continuously operate and maintain the above-described excellent performance.

In addition, the system employing the carbon dioxide capture method 100 of the present invention can be used as a demonstration or test in addition to the chimney exhaust gas produced by the production process.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

100. . . Method of capturing carbon dioxide

102. . . Pre-process

104. . . Provide chimney exhaust step

106. . . Carbon dioxide absorption step

108. . . Primary amine regeneration step

110. . . Carbon dioxide storage step

112. . . Recycling step

For a better understanding of the present invention, reference is made to the above detailed description and the accompanying drawings. It is emphasized that, in accordance with the standard of the industry, the various features in the drawings are not to scale. In fact, the dimensions of the various features may be arbitrarily enlarged or reduced in order to clearly illustrate the above embodiments. The relevant schema description is as follows.

1 is a flow chart showing a method of capturing carbon dioxide according to an embodiment of the present invention, wherein the method of capturing carbon dioxide is suitable for capturing carbon dioxide in a stack exhaust gas.

100. . . Method of capturing carbon dioxide

102. . . Pre-process

104. . . Provide chimney exhaust step

106. . . Carbon dioxide absorption step

108. . . Primary amine regeneration step

110. . . Carbon dioxide storage step

112. . . Recycling step

Claims (11)

A method for capturing carbon dioxide, which is suitable for capturing carbon dioxide in a chimney exhaust gas generated by a combustion furnace, the chimney exhaust gas comprising a plurality of components, wherein the components are carbon dioxide, water, sulfur oxides (SO _X ), nitrogen oxides (NO _X ), unavoidable impurities, and a residue consisting of nitrogen (N ₂ ), the method of capturing carbon dioxide includes: performing a pre-process to remove water, sulfur oxides, nitrogen oxides or An unavoidable impurity; performing a chimney exhaust step to provide the chimney exhaust gas at a first predetermined flow rate, wherein the first predetermined flow rate is 10 cubic meters per hour to 11 cubic meters per hour, and the chimney exhaust gas temperature is 30 °C to 40 ° C; performing a carbon dioxide absorption step to provide a primary amine solution at a second predetermined flow rate, the primary amine solution comprising water and a primary amine, wherein the primary amine absorbs carbon dioxide in the chimney exhaust gas, wherein Providing the primary amine solution at the second predetermined flow rate provides 60 kg to 70 kg of the primary amine per hour; and performing a primary amine regeneration step, This makes the absorbed carbon dioxide from the primary amine of an amine. The method of capturing carbon dioxide according to claim 1, wherein in the pre-process, the sulfur oxides in the chimney exhaust gas removed comprise sulfur dioxide (SO ₂ ). The method of capturing carbon dioxide according to claim 1, wherein the step of providing a chimney exhaust further comprises: providing the chimney exhaust gas from a bottom of an absorption tower. The method of capturing carbon dioxide according to claim 3, wherein the step of absorbing carbon dioxide further comprises: spraying the primary amine solution from the top of the absorption tower. The method for capturing carbon dioxide according to claim 1, wherein the primary amine regeneration step further comprises heating the primary amine solution by a heating device, wherein the heating device has a heating temperature of 100 ° C to 105 ° C. The method for capturing carbon dioxide according to claim 5, wherein the primary amine regeneration step further comprises: spraying the primary amine solution treated by the carbon dioxide absorption step from a top of a stripping column, wherein the heating device is disposed in the steam The bottom of the tower. The method for capturing carbon dioxide according to claim 1, further comprising: performing a carbon dioxide storage step to store the carbon dioxide obtained by the primary amine regeneration step treatment into a specific container. The method for capturing carbon dioxide according to claim 1, further comprising: performing a recycling step of performing the carbon dioxide absorption step on the primary amine solution obtained by the primary amine regeneration step. The method of capturing carbon dioxide according to claim 1, wherein the primary amine is monoethanolamine. The method of capturing carbon dioxide according to claim 1, wherein the primary amine solution comprises 20% by weight of the primary amine in weight percent (wt%). The method for capturing carbon dioxide according to claim 1, wherein the components of the chimney exhaust gas are respectively in a volume percentage (vol%): 26 to 29 vol% of carbon dioxide, 14 to 16 vol% of water, 0.003 to 0.004. Vol% of sulfur oxides and nitrogen oxides, unavoidable impurities, and residues consisting of nitrogen.