JP2007021305A - Method for treating exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating an exhaust gas capable of completely removing a volatile aldehyde contained in the exhaust gas with a simple process. <P>SOLUTION: The method for treating an exhaust gas comprises: introducing an exhaust gas including a volatile aldehyde into a scrubber, and removing the volatile aldehyde contained in the exhaust gas by spraying or injecting water containing at least one kind selected from hydroxylamine sulfate and hydroxylamine hydrochloride into the exhaust gas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment method. More specifically, the present invention relates to an exhaust gas treatment method capable of reliably removing volatile aldehyde contained in exhaust gas by a simple method.

  Exhaust gas emitted from various factories such as chemical factories, food factories, steel factories, wet oxidation of human waste and sludge, drying and incineration of activated sludge, etc. often contains aldehydes, causing odor pollution. ing. Among various exhaust gas treatment methods, there is a cleaning method in which a liquid such as water or an absorbing liquid is brought into contact with exhaust gas to dissolve, absorb or neutralize odor / toxic components and capture them in the liquid.

As the cleaning method, for example, Japanese Patent Application Laid-Open No. 59-199018 (Patent Document 1) proposes a chemical solution cleaning and deodorizing method of odorous gas containing aldehydes using a sodium sulfite aqueous solution added with glycerin as an absorbing solution. ing. This method uses a cleaning deodorizing chemical solution to which glycerin is further added for the purpose of enhancing the deodorizing effect of the existing method using a sodium sulfite aqueous solution as a cleaning deodorizing chemical solution for odor gas. However, when glycerin is used, there is a concern about an increase in BOD and COD in the washed waste water after treatment.
Japanese Patent Laid-Open No. 62-237926 (Patent Document 2) discloses an exhaust gas treatment in which reducing substances such as phenol and formaldehyde in exhaust gas are absorbed and absorbed by an absorbing solution containing hydrogen peroxide and ferrous ions. A method has been proposed.

  On the other hand, Japanese Patent Application Laid-Open No. 56-113342 (Patent Document 3) proposes an adsorbent for a lower aldehyde composed of activated carbon loaded with hydroxylamine hydrochloride or hydroxylamine sulfate. However, the above publication does not describe a method of spraying or injecting water containing hydroxylamine hydrochloride or hydroxylamine sulfate to exhaust gas containing aldehydes.

JP 59-199018 A JP-A-62-237926 JP-A 56-113342

  An object of the present invention is to provide an exhaust gas treatment method capable of reliably removing volatile aldehyde contained in exhaust gas by a simple method.

  The inventor of the present invention has conducted extensive research to solve the above-mentioned problems. As a result, when exhaust gas is treated by a cleaning method, the exhaust gas containing volatile aldehyde was selected from hydroxylamine sulfate and hydroxylamine hydrochloride. It has been found that volatile aldehydes contained in exhaust gas can be reliably and efficiently removed by spraying or spraying water containing at least one species, and the present invention has been completed.

  Thus, according to the present invention, exhaust gas containing a volatile aldehyde is introduced into a scrubber, and water containing at least one selected from hydroxylamine sulfate and hydroxylamine hydrochloride is sprayed or injected into the exhaust gas. An exhaust gas treatment method characterized by removing volatile aldehydes contained in the product is provided.

According to the exhaust gas treatment method of the present invention, the volatile aldehyde contained in the exhaust gas can be surely removed by a simple method, so that the problem of bad odor pollution can be solved and it is extremely useful industrially.

  In the method of the present invention, the scrubber for introducing the exhaust gas may be an exhaust gas treatment apparatus including a step of spraying or injecting a cleaning liquid such as water, and is limited to other processes in the exhaust gas treatment apparatus, the amount of treatment gas flow, and the like. Never happen.

  In addition, commercially available hydroxylamine sulfate and hydroxylamine hydrochloride contained in the water sprayed or sprayed on the exhaust gas by the method of the present invention can be suitably used.

Furthermore, in the method of the present invention, the hydroxylamine is activated by containing at least one selected from hydroxylamine sulfate and hydroxylamine hydrochloride and adjusting the pH of water sprayed or injected to the exhaust gas to 9-12. It is preferable because removal of volatile aldehyde contained in the exhaust gas is promoted. In addition, it is good to use alkaline agents, such as sodium hydroxide and potassium hydroxide, for pH adjustment.

In the method of the present invention, the amount of at least one selected from hydroxylamine sulfate and hydroxylamine hydrochloride contained in water sprayed or sprayed on exhaust gas is such that hydroxylamine is contained in 1 mol of aldehyde groups contained in the exhaust gas. The amount is preferably 0.5 to 1.5 mol, and more preferably 0.5 to 1.0 mol. When the amount of hydroxylamine is less than 0.5 mol, it is not preferable from the point that sufficient volatile aldehyde removal effect cannot be obtained, and even when the amount of hydroxylamine exceeds 1.5 mol, volatile aldehyde The removal effect is not changed, and it is not preferable because it is an economic disadvantage.

On the other hand, the volatile aldehyde contained in the exhaust gas removed by the method of the present invention may be any volatile aliphatic aldehyde or aromatic aldehyde, specifically, formaldehyde, acetaldehyde, propion. Examples include aldehyde, butyraldehyde, acrolein, benzaldehyde, vanillin, cinnamaldehyde and the like.

In addition, the method of the present invention can be used in combination with known exhaust gas cleaning chemicals, adsorbents, etc. or in combination with various exhaust gas treatment methods as long as the effects of the present invention are not impaired.

(Example)
The present invention will be described in detail by test examples, but the present invention is not limited by these test examples.

Test example 1
A 350 mg / L aqueous propionaldehyde solution was prepared, and 200 mL each was dispensed into 6 1 L Erlenmeyer flasks. The odor in each Erlenmeyer flask immediately after adding and dissolving 0.2 g each of the reagent agent was evaluated. In addition, about Example 1 and 2, pH adjustment was performed using 10% sodium hydroxide aqueous solution, and the odor before and after pH adjustment was evaluated.
Further, each Erlenmeyer flask was stoppered and shaken up and down for 1 minute, and then the head space in the Erlenmeyer flask was measured using an aldehyde detector tube (“151L” and “91L” manufactured by GASTEC).
The results are shown in Table 1.

  Compared with the comparative example which is a known aldehyde removal method, it can be seen that Examples 1 and 2 have a remarkable aldehyde removal effect.

Test example 2
An aldehyde removal effect confirmation test was conducted when hydroxylamine sulfate-containing water was simply sprayed onto the vaporized aldehyde.
To 1 L of water, 2 g of hydroxylamine sulfate and 10% sodium hydroxide were added and dissolved to prepare a reagent solution (pH = 11.6).
After putting 0.07 g of propionaldehyde into a 1 L Erlenmeyer flask and stoppering, hot air was applied from the bottom of the flask for 3 minutes with a dryer to evaporate propionaldehyde into the Erlenmeyer flask to adjust the test gas. At this time, the concentration of propionaldehyde in the Erlenmeyer flask is 270000 ppm in calculation.
After adding 100 mL of the reagent solution into the test gas, capping and shaking up and down for 1 minute, the headspace in the Erlenmeyer flask was measured using an aldehyde detector tube (“91L” manufactured by GASTECH), and the result was less than 1 ppm. There was no smell.
From this, it can be seen that propionaldehyde in a vaporized state can be reliably removed by spraying water containing hydroxylamine sulfate.

Test example 3
The test was conducted in the same manner as in Test Example 2 except that acetaldehyde was used instead of propionaldehyde, and “92L” manufactured by Gastec was used as the aldehyde detector tube.
As a result, the aldehyde in the Erlenmeyer flask headspace was less than 1 ppm, and there was no odor.
From this, it can be seen that vaporized acetaldehyde can be reliably removed by spraying hydroxylamine sulfate-containing water.

Claims (3)

By introducing an exhaust gas containing a volatile aldehyde into a scrubber and spraying or injecting water containing at least one selected from hydroxylamine sulfate and hydroxylamine hydrochloride into the exhaust gas, the volatile aldehyde contained in the exhaust gas is removed. An exhaust gas treatment method comprising removing the exhaust gas. The treatment method according to claim 1, wherein the pH of water sprayed or sprayed on the exhaust gas is adjusted to 9-12. At least one amount selected from hydroxylamine sulfate and hydroxylamine hydrochloride contained in water sprayed or sprayed on exhaust gas is 0.5 to 1. hydroxylamine per mole of aldehyde groups contained in the exhaust gas. The processing method according to claim 1 or 2, wherein the amount is 5 mol.