JP2010046599A - Method for regenerating cleaning performance of acidic gas absorbing/removing agent and apparatus for absorbing acidic gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that since the removal performance of the conventional acidic gas absorbing/removing agent is deteriorated gradually owing to long-term use, it is necessary to regenerate the used acidic gas absorbing/removing agent and it is also necessary to restrain the strength reduction thereof when regenerated and shorten the regeneration time. <P>SOLUTION: The acidic gas absorbing/removing agent is obtained by immersing a material which is prepared by mixing a small amount of cellulose ether in a main component comprising calcium sulfate, calcium hydroxide and activated carbon, kneading the obtained mixture, compacting the kneaded mixture and hardening the compacted mixture, in an aqueous solution of a hydroxide or carbonate of sodium or potassium. After the acidic gas absorbing/removing agent is used for a long period of time, the used acidic gas absorbing/removing agent is washed with a sulfite aqueous solution. As a result, the regeneration time can be shortened and the strength reduction thereof when regenerated can be restrained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a purification performance regeneration method for a removing agent that absorbs and removes acidic gases such as nitrogen oxides and sulfur oxides, and further an acidic gas absorption treatment apparatus.

  A remover that absorbs and removes acidic gases such as nitrogen oxides and sulfur oxides is known (see, for example, Patent Document 1). The structure of this conventional acid gas absorption and removal agent is as shown in FIG. 5. 1 is calcium sulfate, 2 is calcium hydroxide, 3 is activated carbon, 4 is amorphous carbon, 5 is sodium or potassium hydroxide or Carbonate.

  There are other acid gas absorption / removal agents having a similar composition, and the amorphous carbon used as a binder is a nonionic water-soluble cellulose ether (see, for example, Patent Document 2). Also known as an acidic gas absorption and removal agent of similar composition is a kneaded and molded cured product comprising an alkali such as an alkali metal or alkali metal earth metal hydroxide or carbonate, a cement material such as calcium sulfate, and powdered activated carbon. (For example, see Patent Document 3).

When the activity of these acidic gas absorption / removal agents decreases after long-term use, the purification performance is regenerated mainly by washing with water.
Japanese Patent No. 2778031 JP 2004-230322 A JP 52-123987 A

  Conventional acid gas absorption / removal agents have reduced activity and reduced purification performance when acid gas components (nitric acid compounds) that have been absorbed in the removal agent after long-term use are accumulated. As a method for regenerating the purification performance, the purification performance has been regenerated by washing with water and eluting the nitrate compound accumulated in the acid gas absorption and removal agent into water. According to this method, there is a problem that calcium sulfate, calcium hydroxide and the like, which are components of the absorption removing agent, are eluted together with the nitric acid compound in the washing water, and the strength of the absorption removing agent itself is reduced. Moreover, in order to elute the nitrate compound accumulated in the absorption and removal agent, 4 to 5 hours of washing time is required, and it has been required to shorten the regeneration time.

  In order to solve the above-mentioned problems, the present invention immerses a kneaded molded cured product obtained by mixing a small amount of cellulose ether with the main components of calcium sulfate, calcium hydroxide and activated carbon in an aqueous solution of sodium or potassium hydroxide or carbonate. In order to recover the activity of products that have been used for a long time by absorbing a large amount of acid gases such as nitrogen oxides and sulfur oxides, It is to be washed with.

  Furthermore, in the present invention, the acid gas absorption and removal agent washed with the sulfite aqueous solution is immersed in an aqueous solution of sodium or potassium hydroxide or carbonate, thereby regenerating the purification performance of the absorption removal agent and the purification performance duration after regeneration. Is intended to be extended.

  According to the present invention, it is possible to suppress the strength reduction of the absorbent removal agent itself by water washing and to shorten the regeneration time.

  Further, when this acidic gas absorption / removal agent is a treatment device arranged in a gas flow path through which a gas containing nitrogen dioxide or sulfur dioxide flows, an acidic gas having an excellent acidic gas absorption capacity at an atmospheric temperature of -20 to 120 ° C. An absorption processing apparatus can be realized.

  The acid gas absorption / removal agent regeneration method according to the first aspect of the present invention comprises a kneaded and molded product obtained by mixing a small amount of cellulose ether with the main components of calcium sulfate, calcium hydroxide and activated carbon, an aqueous solution of sodium or potassium hydroxide or carbonate In the acidic gas absorption / removal agent obtained by immersing in water, the absorption / removal agent after long-term use is washed with a sulfite aqueous solution to recover the activity of the absorption / removal agent. This makes it possible to recover the acid gas purification performance of the acid gas absorption and removal agent that has continued to be used for a long period of time and the acid gas removal performance has been reduced. Therefore, high acid gas removal performance can be maintained for a long time. Furthermore, the playback time can be shortened.

  In the method for regenerating an acidic gas absorption / removal agent of the second invention, the aqueous sulfite solution used in the first invention is an aqueous sodium sulfite solution. As a result, a decrease in strength of the absorption / removal agent itself can be suppressed, and a high acid gas removal performance can be maintained for a long time because it can be used repeatedly. Furthermore, the playback time can be shortened.

  In the method for regenerating an acidic gas absorption and removal agent of the third invention, the concentration of the aqueous sodium sulfite solution used in the second invention is 0.2 to 5% by weight. Since the concentration of the acid gas absorption and removal agent regeneration solution is optimized, it is possible to further suppress the strength reduction of the absorption and removal agent itself and to maintain high acid gas removal performance for a long time because it can be used repeatedly. it can. Furthermore, the playback time can be shortened.

  The acid gas absorption / removal agent regeneration method of the fourth invention is the acid gas absorption / removal agent regeneration method according to any one of items 1 to 3, wherein the acid gas absorption / removal agent regeneration method is washed with a sulfite aqueous solution, dried and then immersed in an aqueous sodium hydroxide solution. This is a purification performance regeneration method for recovering the activity of the absorption remover. Thereby, besides the suppression of the strength reduction of the absorption / removal agent itself, the acid gas removal performance of the absorption / removal agent after regeneration can be kept high for a long period of time.

  The acid gas absorption / removal agent regeneration method of the fifth invention is the acid gas absorption / removal agent regeneration method according to any one of items 1 to 3, wherein the acid gas absorption / removal agent regeneration method is washed with a sulfite aqueous solution, dried and then immersed in an aqueous potassium hydroxide solution. This is a purification performance regeneration method for recovering the activity of the absorption remover. Thereby, besides the suppression of the strength reduction of the absorption / removal agent itself, the acid gas removal performance of the absorption / removal agent after regeneration can be kept high for a long period of time.

  The acid gas absorption / removal agent regeneration method of the sixth invention is the acid gas absorption / removal agent regeneration method according to any one of items 1 to 3, wherein the acid gas absorption / removal agent regeneration method is washed with an aqueous sulfite solution, dried and then immersed in an aqueous sodium carbonate solution. This is a purification performance regeneration method for recovering the activity of the absorption remover. Thereby, besides the suppression of the strength reduction of the absorption / removal agent itself, the acid gas removal performance of the absorption / removal agent after regeneration can be kept high for a long period of time.

  The acid gas absorption / removal agent regeneration method of the seventh invention is the acid gas absorption / removal agent regeneration method according to any one of items 1 to 3, wherein the acid gas absorption / removal agent regeneration method is washed with a sulfite aqueous solution, dried and then immersed in an aqueous potassium carbonate solution. This is a purification performance regeneration method for recovering the activity of the absorption remover. Thereby, besides the suppression of the strength reduction of the absorption / removal agent itself, the acid gas removal performance of the absorption / removal agent after regeneration can be kept high for a long period of time.

  The processing apparatus for absorbing acidic gas according to the eighth invention is a gas in which a gas containing nitrogen dioxide or sulfur dioxide flows as the acidic gas absorption / removal agent obtained by the regeneration method according to any one of the first to seventh aspects. A treatment apparatus for removing the acidic gas arranged in the flow path was used. The acid gas absorption / removal agent has an excellent acid gas absorption capacity because it is maintained at an optimum temperature of -20 to 120 ° C. Since the acid gas absorption / removal agent is placed in an atmosphere that does not exceed 120 ° C., it suppresses dehydration of the component calcium sulfate and volume expansion and thermal decomposition of the cellulose ether of this composition. The life is not reduced. As a result, an acid gas absorption treatment apparatus that satisfies the acid gas removal performance and can repeatedly use the acid gas absorption / removal agent that has been used for a long time and has decreased activity is obtained.

  In the acidic gas absorption treatment apparatus of the ninth invention, the acidic gas absorption treatment apparatus used in the eighth invention is applied to an apparatus for purifying automobile tunnel exhaust gas or automobile roadside atmosphere. The exhaust gas from the automobile tunnel and the atmosphere along the automobile road have an advantage that the relative humidity is higher than the general environment due to moisture contained in the automobile exhaust gas, and the purification performance of nitrogen oxides and sulfur oxides is improved. For this reason, it is possible to absorb and remove nitrogen oxides and sulfur oxides contained in automobile tunnel exhaust gas or automobile roadside atmosphere over a long period of time.

(Embodiment 1)
FIG. 4 shows a processing apparatus in which the acidic gas absorption / removal agent obtained by the regeneration method of the present invention is disposed in a gas flow path through which a gas containing nitrogen dioxide or sulfur dioxide flows. The acid gas absorption / removal agent is maintained in an atmosphere of -20 to 120 ° C. Therefore, it has an excellent acid gas absorption capacity. In addition, since the acid gas absorption / removal agent is arranged in a temperature atmosphere that does not exceed 120 ° C., calcium sulfate, which is a component thereof, dehydrates and expands in volume, and the cellulose ether of this composition is thermally decomposed. Is suppressed, and the lifetime is not reduced. As a result, an acid gas absorption treatment apparatus that satisfies the acid gas removal performance and can repeatedly use the acid gas absorption / removal agent that has been used for a long time and has decreased activity is obtained. Furthermore, the present acid gas absorption treatment apparatus can be applied to an automobile tunnel. The automobile tunnel has the advantage that the relative humidity is higher than the general environment due to the moisture contained in the automobile exhaust gas, and the purification performance of nitrogen oxides and sulfur oxides is improved. For this reason, nitrogen oxides and sulfur oxides contained in automobile tunnel exhaust gas can be absorbed and removed for a long time.

  Examples will be described in detail below.

  FIG. 1 is a regeneration flow chart of an acid gas absorption / removal agent according to an embodiment of the present invention. The results of a regeneration test performed by this method are shown below.

Example 1
The acid gas absorption and removal agent in which actual diesel exhaust gas was passed as acid gas was used as a test sample, and the sample was washed with a washing solution, and the total amount of nitrogen eluted in the washing water after washing was measured. The cleaning liquid was water and a sodium sulfite aqueous solution (concentration 5%). The washing time was 1 hour, 2.5 hours, and 4 hours.

  The test results are shown in FIG. The total nitrogen elution amount was set to 100 as the conventional regeneration method (water washing, 4 hours), and the total nitrogen elution amount by each regeneration method was compared. The regeneration method using a sodium sulfite aqueous solution (concentration 5%) obtained a cleaning effect equivalent to or higher than that of the conventional method by setting the cleaning time to a quarter or more of the conventional method. Therefore, the regeneration time can be shortened by the regeneration method using an aqueous sodium sulfite solution. In addition, when this test was repeated 20 times, the sample was slightly cracked or chipped by the conventional method, but the sample was not cracked or chipped by regeneration with an aqueous sodium sulfite solution, and the strength of the absorbent remover was reduced by regeneration. It was confirmed that

(Example 2)
The same test as in Example 1 was carried out with a washing time of 1 hour and the washing water in three patterns with a sodium sulfite aqueous solution concentration of 0.2%, 1.0% and 5.0%.

  The test results are shown in FIG. A cleaning effect equivalent to that of the conventional method was obtained by cleaning the acidic gas absorbing / removing agent for 1 hour with an aqueous sodium sulfite concentration of 0.2% to 5.0%. When the concentration of the sodium sulfite aqueous solution is less than 0.2%, the cleaning effect is further reduced. Therefore, when the cleaning time is 1 hour, the concentration of the sodium sulfite aqueous solution is preferably 0.2% or more. On the other hand, when the concentration of the sodium sulfite aqueous solution exceeds 5.0%, the amount of sodium sulfite used in one cleaning step is excessively increased, resulting in an increase in cleaning cost.

  In addition, when this test was repeated 20 times, the sample was slightly cracked or chipped by the conventional method, but the sample was not cracked or chipped by regeneration with an aqueous sodium sulfite solution, and the strength of the absorbent removal agent decreased due to regeneration. It was confirmed that Therefore, according to the present embodiment, the concentration of the sodium sulfite aqueous solution used for the washing water is set to 0.2% to 5.0%, thereby reducing the regeneration time while suppressing the decrease in the strength of the acid gas absorption and removal agent. be able to.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a method for regenerating an acid gas absorption / removal agent used in automobile tunnel exhaust gas or an acid gas absorption treatment apparatus installed along a road.

Reproduction method flow chart according to one embodiment of the present invention The graph which shows the test result by Example 1 of this invention The graph which shows the test result by Example 2 of this invention Acid gas absorption processing system diagram showing the first embodiment of the present invention Cross section of conventional acid gas absorption and removal agent

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Calcium sulfate 2 Calcium hydroxide 3 Activated carbon 4 Amorphous carbon 5 Sodium or potassium hydroxide or carbonate 6 Acid gas absorption removal agent 7 Gas flow path 8 Acid gas absorption treatment device

Claims (9)

In the acid gas absorption and removal agent obtained by immersing a kneaded molded cured product in which a small amount of cellulose ether is mixed with the main components of calcium sulfate, calcium hydroxide and activated carbon in an aqueous solution of sodium or potassium hydroxide or carbonate. A purification performance regeneration method for recovering the activity of the absorption removing agent by washing the absorption removing agent with a sulfite aqueous solution after a period of use. The absorption removal agent purification performance regeneration method according to claim 1, wherein the sulfite is sodium sulfite. The method according to claim 2, wherein the concentration of the aqueous sodium sulfite solution is 0.2 to 5% by weight. 4. The method for regenerating purification performance of an acid gas absorption / removal agent according to any one of claims 1 to 3, wherein the activity of the absorption / removal agent is recovered by washing with a sulfite aqueous solution, drying, and immersing in an aqueous sodium hydroxide solution. 4. The method for regenerating purification performance of an acid gas absorption / removal agent according to any one of claims 1 to 3, wherein the activity of the absorption / removal agent is recovered by washing with a sulfite aqueous solution, drying, and immersing in an aqueous potassium hydroxide solution. 4. The method for regenerating purification performance of an acid gas absorbing / removing agent according to any one of claims 1 to 3, wherein the activity of the absorbing / removing agent is recovered by washing with an aqueous sulfite solution, drying, and immersing in an aqueous sodium carbonate solution. 4. The method for regenerating purification performance of an acid gas absorption / removal agent according to any one of claims 1 to 3, wherein the activity of the absorption / removal agent is recovered by washing with a sulfite aqueous solution, drying, and immersing in an aqueous potassium carbonate solution. The acid gas absorption / removal agent is a treatment apparatus arranged in a gas flow path through which a gas containing nitrogen dioxide or sulfur dioxide flows, and the acid gas absorption / removal agent is brought into contact at an atmospheric temperature of -20 to 120 ° C. An acidic gas absorption treatment apparatus that removes the acidic gas in the gas by using the regeneration method according to any one of claims 1 to 7, even if the activity of the absorbent removal agent decreases after long-term use. An acidic gas absorption treatment apparatus capable of repeatedly using the absorption and removal agent. The acid gas absorption treatment apparatus according to claim 8, wherein the acid gas absorption / removal agent is installed along an automobile tunnel or an automobile road to purify the exhaust gas from the automobile tunnel or the atmosphere along the automobile road.

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