JP2011177685A - Purification device and carbon dioxide recovery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purification device that efficiently removes impurities accumulated in an absorbing liquid used for a system for recovering the carbon dioxide in a combustion exhaust gas, and to provide a carbon dioxide recovery system using the same. <P>SOLUTION: The carbon dioxide recovery system includes: an absorbing tower 103 for making the absorbing liquid absorb the carbon dioxide contained in the combustion exhaust gas; a regenerating tower 105 for regenerating the absorbing liquid by removing the carbon dioxide from the absorbing liquid discharged from the absorbing tower; and a purification device 10 for purifying the absorbing liquid by removing anions existing in the absorbing liquid from the absorbing liquid discharged from the regenerating tower. The purification device includes a support body comprising a metal mesh or a porous polymer membrane, wherein a compound layer including a barium compound is formed thereon, and makes the anions absorbing liquid pass through the absorbing liquid to react the anions with barium ions and fixes to the compound layer, and provides a purified absorbing liquid to the absorbing tower. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a purification device and a carbon dioxide recovery system.

  In recent years, for thermal power plants that use large amounts of fossil fuels, a method for separating and recovering carbon dioxide in combustion exhaust gas by bringing the combustion exhaust gas into contact with an amine-based absorbent and releasing the recovered carbon dioxide to the atmosphere Research has been done on how to store without doing.

  Specifically, an absorption tower that absorbs carbon dioxide contained in combustion exhaust gas in an amine-based absorption liquid and an absorption liquid (rich liquid) that has absorbed carbon dioxide are supplied from the absorption tower, the rich liquid is heated, and the rich liquid A carbon dioxide recovery system including a regeneration tower that regenerates an absorbing solution by releasing carbon dioxide gas from the carbon dioxide is known (for example, see Patent Document 1).

  The combustion exhaust gas may contain solids such as nitrogen, oxygen, other acidic gas components, nitrogen oxides, sulfur oxides, hydrogen chloride, and dust in addition to carbon dioxide. Since the amine-based absorbing liquid is alkaline, it absorbs components other than carbon dioxide in these exhaust gases. When dust is taken into the absorption liquid, the components of dust, such as calcium, sodium, and silicon, are slightly eluted as ions.

  Since the absorbing liquid circulates in the apparatus, metal ion components eluted from the surface of the structural material, such as iron ions and chromium ions, are accumulated in the liquid as the plant structural material progresses in corrosion. In addition, since the amine as the main component of the absorbing liquid is an organic substance, by repeating heating and cooling cycles of the liquid, the thermal decomposition of the amine component proceeds, and organic acids such as formic acid, acetic acid, glycolic acid, propionic acid, oxalic acid Etc. are generated.

  When these impurities accumulate in the system, scales are generated in the regenerative heat exchanger, reboiler, and the like, and there is a problem that the amount of energy required for releasing carbon dioxide from the liquid is increased. Further, there is a problem that the pH of the absorbing solution is biased to the acidic side due to the absorption of the acidic gas, and the carbon dioxide absorbing ability of the absorbing solution is lowered.

  For this reason, when the absorbing solution is continuously used, it is necessary to periodically remove these impurities. Conventionally, an amine solution has been regenerated by removing a solid content using a filter and removing an ionic component after removing the solid content. However, a multi-stage filter or the like is provided, and there is a problem that an installation space for the apparatus becomes large.

  A technique for removing impurities contained in a liquid, particularly an ionic component, using an anion exchange resin and a cation exchange resin is known (see, for example, Patent Document 2). However, when the temperature of the ion exchange resin exceeds 100 ° C., the exchange group becomes unstable and elutes, so it is necessary to perform the treatment at a low liquid temperature. Therefore, when removing impurities, the temperature of the absorbing solution is lowered, and there is a problem that heat loss increases.

JP-A-2005-254212 JP 2009-215186 A

  An object of this invention is to provide the purification apparatus and carbon dioxide recovery system which remove efficiently the impurities which exist in absorption liquid with little heat loss.

  A purification apparatus according to an aspect of the present invention includes a container, a first line for introducing a liquid containing an anion into the container, a support provided in the container and made of a metal mesh or a porous polymer membrane, and the A filter having a compound layer formed on the surface of the support and containing a barium compound, and a second line for discharging the liquid that has passed through the filter from the container.

  A carbon dioxide recovery system according to an aspect of the present invention is provided with an absorption tower that absorbs carbon dioxide contained in combustion exhaust gas into an absorption liquid and discharges the absorption liquid containing carbon dioxide, and an absorption liquid discharged from the absorption tower is supplied. A carbon dioxide gas containing vapor from the absorption liquid, and regenerating and discharging the absorption liquid; a reboiler connected to the regeneration tower and heating the absorption liquid in the regeneration tower; An absorption liquid that is provided between the absorption tower and the regeneration tower and that is discharged from the regeneration tower and supplied to the absorption tower is used as a heat source. A regenerative heat exchanger that heats, and a purification device that purifies the absorption liquid by removing anions from the absorption liquid in the regeneration tower or the absorption liquid discharged from the regeneration tower, the purification apparatus comprising: a container; , Before the absorption liquid A first line to be introduced into the container; a support provided in the container and made of a metal mesh or a porous polymer film; and a compound layer formed on the surface of the support and containing a barium compound, And a second line for discharging the absorbing liquid that has passed through the filter from the container.

  A carbon dioxide recovery system according to an aspect of the present invention is provided with an absorption tower that absorbs carbon dioxide contained in combustion exhaust gas into an absorption liquid and discharges the absorption liquid containing carbon dioxide, and an absorption liquid discharged from the absorption tower is supplied. A carbon dioxide gas containing vapor from the absorption liquid, and regenerating and discharging the absorption liquid; a reboiler connected to the regeneration tower and heating the absorption liquid in the regeneration tower; An absorption liquid that is provided between the absorption tower and the regeneration tower and that is discharged from the regeneration tower and supplied to the absorption tower is used as a heat source. A regenerative heat exchanger that heats, and a purification device that purifies the absorption liquid by removing anions from the absorption liquid discharged from the absorption tower, the purification apparatus containing a container and the absorption liquid in the container First line to introduce And a filter that is provided in the container and includes a metal mesh or a porous polymer film, and a compound layer that is formed on the surface of the support and includes a barium compound, and removes anions from the absorbing solution. And a second line for discharging the absorption liquid that has passed through the filter from the container.

  According to the present invention, impurities present in the absorbing liquid can be efficiently removed with little heat loss.

1 is a schematic configuration diagram of a carbon dioxide recovery system according to a first embodiment of the present invention. It is a schematic block diagram of the purification apparatus. It is a schematic block diagram of a filter. It is a figure which shows the example in which a support | carrier carries an adjuvant. It is a schematic block diagram of the purification apparatus by a modification. It is a schematic block diagram of the carbon dioxide collection system which concerns on the 2nd Embodiment of this invention. It is a graph which shows transition of the sulfate ion concentration in the absorption liquid which circulates a system. It is a schematic block diagram of the carbon dioxide collection system by a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (First Embodiment) FIG. 1 shows a schematic configuration of a carbon dioxide recovery system according to a first embodiment of the present invention. Here, the carbon dioxide recovery system recovers carbon dioxide contained in combustion exhaust gas generated by the combustion of fossil fuel using an absorbing liquid capable of absorbing carbon dioxide. As the absorbing solution capable of absorbing carbon dioxide, for example, an amine compound aqueous solution in which an amine compound is dissolved in water is used.

  As shown in FIG. 1, the carbon dioxide recovery system 1 includes an absorption tower 103 that absorbs carbon dioxide contained in the combustion exhaust gas 102a into an absorption liquid, and an absorption liquid that absorbs carbon dioxide from the absorption tower 103 (hereinafter, rich liquid 104a and A regenerating tower that heats the rich liquid 104a, releases carbon dioxide gas containing steam from the absorbing liquid, discharges exhaust gas 102c containing carbon dioxide gas and steam, and regenerates the absorbing liquid. 105.

  For example, the combustion exhaust gas 102a generated in a power generation facility such as a thermal power plant is supplied to the lower part of the absorption tower 103, and the combustion exhaust gas 102b from which carbon dioxide has been removed is discharged from the top of the absorption tower 103. .

  The reboiler 106 heats a part of the lean liquid 104 b stored in the regeneration tower 105 to raise its temperature to generate steam, and supplies the steam to the regeneration tower 105. When heating the lean solution 104b in the reboiler 106, a small amount of carbon dioxide gas is released from the lean solution 104b and supplied to the regeneration tower 105 together with the vapor. Then, the rich liquid 104a is heated in the regeneration tower 105 by this steam, and carbon dioxide gas is released.

  Regenerative heat exchange is performed between the absorption tower 103 and the regeneration tower 105 by using the lean liquid 104b supplied from the regeneration tower 105 to the absorption tower 103 as a heat source and heating the rich liquid 104a supplied from the absorption tower 103 to the regeneration tower 105. A container 107 is provided and configured to recover the heat of the lean liquid 104b. The lean liquid 104 b from the regenerative heat exchanger 107 is cooled by the cooler 114 and supplied to the upper part of the absorption tower 103.

  The lean liquid 104 b supplied to the upper part of the absorption tower 103 descends from the upper part in the absorption tower 103. On the other hand, the flue gas 102 a supplied to the absorption tower 103 rises from the lower part toward the top in the absorption tower 103. Therefore, the combustion exhaust gas 102a containing carbon dioxide and the lean liquid 104b come into countercurrent contact (direct contact), and carbon dioxide is removed from the combustion exhaust gas 102a and absorbed by the lean liquid 104b, thereby generating the rich liquid 104a. The combustion exhaust gas 102 b from which carbon dioxide has been removed is discharged from the top of the absorption tower 103.

The combustion exhaust gas 102a is supplied to the absorption tower 103 after passing through denitration, dust removal, and desulfurization processes, but is not completely removed by these processes. These trace components remaining in the combustion exhaust gas 102a are absorbed by the lean liquid 104b together with carbon dioxide in the absorption tower 103. Therefore, the absorption liquid contains anions such as sulfate ions (SO ₄ ²⁻ ) and oxalate ions ((COO) ₂ ²⁻ ) as impurities.

  The purification device 10 removes anions from the absorbing solution, and is connected to a line 110 that guides the absorbing solution in the regeneration tower 105 to the reboiler 106. The absorption liquid is supplied to the purification device 10 via the inflow line 13, and the absorption liquid purified by the purification device 10 is returned to the line 110 via the outflow line 14. The configuration of the purification device 10 will be described later.

  The gas cooler 116 condenses the exhaust gas 102 c discharged from the regeneration tower 105 using cooling water (cooling medium) and supplies the condensed gas to the gas-liquid separator 117.

  The gas-liquid separator 117 separates the moisture-condensed exhaust gas 102c into carbon dioxide gas and reflux water containing an absorbing liquid component. The carbon dioxide gas 102d discharged from the gas-liquid separator 117 is stored in a storage facility (not shown). The reflux water from the gas-liquid separator 117 is returned to the regeneration tower 105.

  Next, the structure of the purification apparatus 10 is demonstrated using FIGS. FIG. 2 shows an example of the configuration of the purification device 10. The purification device 10 is a filter having a container 11 and a filter 12. The container 11 has an upper part and a lower part joined together by a flange. Absorbing liquid is supplied to the lower part of the container 11 of the purification device 10 via the inflow line 13. The absorbing liquid flows through the container 11 and is filtered by the filter 12. The absorption liquid filtered by the filter 12 is returned to the line 110 from the upper part of the container 11 through the outflow line 14.

  As shown in FIG. 3, the filter 12 includes a metal mesh 21 and a barium compound layer 22. The metal mesh 21 is a support that supports the barium compound layer 22 and has a hollow structure. The barium compound layer 22 is a filter aid formed on the surface of the metal mesh 21. The absorbing solution passes through the barium compound layer 22 and the metal mesh 21 and flows to the upper portion of the container 11 through the hollow portion.

  The metal mesh 21 is required to have chemical resistance, particularly not to be eluted in an alkaline atmosphere. Accordingly, the metal mesh 21 is desirably a nickel-based alloy or a metal mesh made of stainless steel containing a large amount of Cr, preferably stainless steel containing 20 wt% or more of Cr.

  The barium compound layer 22 is a metal barium compound made of powder or porous particles. As shown in FIG. 4, the barium compound may be supported on a carrier having many fine pores such as activated carbon and zeolite.

Anions such as sulfate ions (SO ₄ ²⁻ ) and oxalate ions ((COO) ₂ ²⁻ ) present in the absorbing solution react with barium ions. The barium ions contained in the metal-based barium compound of the barium compound layer 22 and the anion in the absorption liquid react chemically, and are deposited and fixed on the surface of the metal-based barium compound as a solid content. Thereby, an anion can be removed from the absorbing solution.

  In addition, the barium compound layer 22 also removes the solid content in the absorbent. By providing the barium compound layer 22, it is possible to remove a solid content having a smaller particle diameter than when the solid content is removed only by the metal mesh 21.

  Although barium ions may be slightly eluted from the barium compound into the absorbing solution, the barium ions themselves do not cause a significant decrease in the performance of the absorbing solution. Therefore, the barium compound is suitable for a material used for removing anions in the absorbing solution. Moreover, since the solid content in the absorbing liquid is not in direct contact with the metal mesh 21, the progress of clogging can be delayed.

  In the present embodiment, various compounds containing barium can be used as the barium compound used in the filter 12, but it is particularly insoluble in an amine solution and does not contain ions that cause scale or ions to be removed. It is preferred to use a barium compound. Further, a barium compound having a high melting point and high thermal stability is more preferable, for example, barium titanate or barium zirconate is preferable. A mixture of barium titanate and barium zirconate may also be used.

  Since barium compounds do not dissolve even at high temperatures, impurities (anions) and solids in the absorption liquid can be effectively removed while the absorption liquid is kept at a high temperature. Therefore, heat loss can be suppressed and fouling of the line for feeding the absorbing liquid can be prevented.

  Since the purification device 10 removes the anions before the absorption liquid is sent to the absorption tower 103, the purification tower 10 can efficiently remove the acidic gas contained in the combustion exhaust gas 102a in the absorption tower 103. Further, scale generation in the regenerative heat exchanger 107 and the reboiler 106 can be prevented, and an increase in energy necessary for releasing carbon dioxide can be prevented.

  Thus, in this embodiment, by using a barium compound, impurities (anions) present in the absorbing liquid can be efficiently removed with little heat loss. In addition, since the ions and solids contained in the absorbing solution can be removed together, the process for removing impurities can be simplified and the cost can be reduced.

  In the first embodiment, the purification device 10 is connected to the line 110. However, the purification device 10 is provided between the regeneration tower 105 and the regeneration heat exchanger 107, and impurities in the lean liquid 104b discharged from the regeneration tower 105 are removed. You may make it remove.

  In the filter 12, a porous polymer film having excellent heat resistance may be used instead of the metal mesh 21. Since the polymer film is required to have chemical resistance, a polymer film composed of a fluorine-containing polymer such as polytetrafluoroethylene is preferable. When the polymer membrane is used, the structure of the filter 12 is preferably a hollow fiber type or a pleated type that can be repeatedly used by backwashing or the like.

  The purification device 10 may be constituted by a body feed type filter as shown in FIG. This is a configuration in which a branch line 31, a filter aid introduction line 32, a tank 33, and a liquid feed line 34 are further provided in the purification device 10 shown in FIG. In addition, the filter of the purification apparatus 10 may be comprised only with the metal mesh 21, and may be comprised with the metal mesh 12 and the barium compound layer 22 as shown in FIG.

  The branch line 31 guides part of the absorbent flowing through the inflow line 13 to the tank 33. The filter aid introduction line 32 introduces the filter aid into the tank 33. The filter aid is a barium compound. The tank 33 mixes the absorbent and the filter aid. The liquid feed line 34 returns the absorbent mixed with the filter aid from the tank 33 to the inflow line 13. The absorbent is filtered in the container 11 and discharged via the outflow line 14.

  In the filter 12 in the container 11, the solid content contained in the absorbent and the barium compound added as a filter aid are collected. The resistance of the particles is reduced by the body feed, the amount of filtration can be increased, and the filtration time can be increased. By taking a longer filtration time, the contact time between the barium compound and the absorbing liquid becomes longer, so that impurities (anions) can be more efficiently removed.

  The washing apparatus 10 may use a reaction layer (fixed bed) filled with a carrier carrying a barium compound instead of a filter using a filter. By using a fixed bed, the contact time between the absorbing liquid and the barium compound is increased, and anions can be more efficiently removed from the liquid.

  (Second Embodiment) FIG. 6 shows a schematic configuration of a carbon dioxide recovery system according to a second embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 in that the purification device 10 is provided between the absorption tower 103 and the regenerative heat exchanger 107 and removes impurities from the rich liquid 104a. . In FIG. 6, the same parts as those of the first embodiment shown in FIG.

  The rich liquid 104a contains not only carbon dioxide absorbed by the absorption tower 103 but also a large amount of impurities. The purification device 10 removes solids and anions in the absorption liquid before the absorption liquid is heated in the regeneration heat exchanger 107 and the regeneration tower 105.

  Thereby, the heat loss at the time of heating up absorption liquid in the regeneration tower 105 can be reduced. Further, the impurities contained in the absorbing solution have an effect of promoting the decomposition of amines when the absorbing solution is heated. Therefore, the purification device 10 can prevent changes in the absorption liquid characteristics by removing these impurities before raising the temperature of the absorption liquid.

  The purification device 10 can be provided at any location where the absorbent in the carbon dioxide recovery system flows. For example, it may be provided between the cooler 114 and the absorption tower 103 to remove impurities from the lean liquid 104b.

  Since the absorption liquid that has passed through the cooler 114 has a low temperature, ion removal by ion exchange treatment using an ion exchange resin that cannot be used under high temperature conditions may be performed in the subsequent stage of the purification device 10. Thereby, impurities contained in the liquid can be further removed.

  FIG. 7 shows the transition of the sulfate ion concentration in the absorption liquid circulating in the carbon dioxide recovery system when the ion exchange treatment is applied. Impurities are also absorbed with the absorption of carbon dioxide in the absorption tower 103, and the concentration of sulfate ions in the absorption liquid increases. Thereafter, after the absorption liquid is discharged from the absorption tower 103, it is regenerated in the regeneration tower 105, is discharged from the regeneration tower 105, and reaches the regeneration heat exchanger 107. The sulfate ion concentration decreases. And the ion exchange process is performed with respect to the absorption liquid which passed the cooler 114, and the sulfate ion concentration in an absorption liquid further falls. In this way, since the sulfate ion concentration of the absorbing solution can be made extremely small, it is possible to prevent deterioration of carbon dioxide absorption performance.

  As shown in FIG. 8, the purification device 10 may be provided at two places between the line 110 and between the absorption tower 103 and the regenerative heat exchanger 107. Thus, by providing the purification device 10 at a plurality of locations, impurities in the absorbent can be further removed. Further, while the purification process in one of the purification apparatuses 10 is stopped and the filter 12 is exchanged, the purification process can be performed by the other purification apparatus 10.

  Although the example which uses the purification apparatus 10 in a carbon dioxide recovery system was demonstrated in the said embodiment, the purification apparatus 10 is applicable to the various situations where the anion removal in a liquid is requested | required.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 Purification apparatus 103 Absorption tower 105 Regeneration tower 106 Reboiler 107 Regenerative heat exchanger

Claims (8)

A container,
A first line for introducing a liquid containing anions into the container;
A filter provided in the container, comprising a support made of a metal mesh or a porous polymer film, and a compound layer formed on the surface of the support and containing a barium compound;
A second line for discharging the liquid that has passed through the filter from the container;
A purification device comprising: An absorption tower for absorbing carbon dioxide contained in the combustion exhaust gas into the absorption liquid and discharging the absorption liquid containing carbon dioxide;
An absorption liquid discharged from the absorption tower is supplied, a carbon dioxide gas containing steam is removed from the absorption liquid, and a regeneration tower that regenerates and discharges the absorption liquid;
A reboiler connected to the regeneration tower for heating the absorption liquid in the regeneration tower;
Absorbing liquid provided between the absorption tower and the regeneration tower, discharged from the regeneration tower and supplied to the absorption tower as a heat source, and discharged from the absorption tower and supplied to the regeneration tower A regenerative heat exchanger that heats,
A purification device for purifying the absorbent by removing anions from the absorbent in the regeneration tower or the absorbent discharged from the regeneration tower;
With
The purification device comprises:
A container,
A first line for introducing the absorbent into the container;
A filter provided in the container, having a support made of a metal mesh or a porous polymer film, and a compound layer formed on the surface of the support and containing a barium compound, and for removing anions from the absorbing solution;
A second line for discharging the absorption liquid that has passed through the filter from the container;
A carbon dioxide recovery system comprising:   The carbon dioxide recovery system according to claim 2, wherein the purification device removes anions from the absorption liquid heated by the reboiler. An absorption tower for absorbing carbon dioxide contained in the combustion exhaust gas into the absorption liquid and discharging the absorption liquid containing carbon dioxide;
An absorption liquid discharged from the absorption tower is supplied, a carbon dioxide gas containing steam is removed from the absorption liquid, and a regeneration tower that regenerates and discharges the absorption liquid;
A reboiler connected to the regeneration tower for heating the absorption liquid in the regeneration tower;
Absorbing liquid provided between the absorption tower and the regeneration tower, discharged from the regeneration tower and supplied to the absorption tower as a heat source, and discharged from the absorption tower and supplied to the regeneration tower A regenerative heat exchanger that heats,
A purification device for purifying the absorption liquid by removing anions from the absorption liquid discharged from the absorption tower;
With
The purification device comprises:
A container,
A first line for introducing the absorbent into the container;
A filter provided in the container, having a support made of a metal mesh or a porous polymer film, and a compound layer formed on the surface of the support and containing a barium compound, and for removing anions from the absorbing solution;
A second line for discharging the absorption liquid that has passed through the filter from the container;
A carbon dioxide recovery system comprising:   5. The carbon dioxide recovery system according to claim 4, further comprising a second purification device that purifies the absorbent by removing anions from the absorbent in the regeneration tower or the absorbent discharged from the regeneration tower. .   The carbon dioxide recovery system according to any one of claims 2 to 5, wherein the barium compound contains barium titanate and / or barium zirconate.   The carbon dioxide recovery system according to any one of claims 2 to 6, wherein the metal mesh is made of a nickel-based alloy or stainless steel containing 20 wt% or more of chromium. The purification device comprises:
A tank,
A third line for guiding a part of the absorbent flowing through the first line to the tank;
A fourth line for supplying a barium compound to the tank;
A fifth line for returning the mixed liquid of the absorbing liquid and the barium compound in the tank to the first line;
The carbon dioxide recovery system according to claim 2, further comprising:

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