JPS59199018A - Deodorizing method - Google Patents

Abstract

PURPOSE:To reduce the decomposition of Na2SO3 even in a hot gas and to enhance the odorizing effect by using an aq. soln. of Na2SO3, added with glycerine, as an absorbing liquid. CONSTITUTION:An odorous gas contg. aldehydes, is introduced into an absorption tower 1. An absorbing liquid consisting of an aq. soln. of Na2SO3 added with glycerine is sprinkled over a packing material layer 2 from a circulation storage tank 5 while controlling the flow rate with a flowmeter 8, and the gas is deodorized by contact with the liquid.

Description

[Detailed description of the invention] The present invention relates to a chemical cleaning and deodorizing method.

More specifically, the present invention relates to a method for deodorizing odor gases containing aldehydes.

Odor gases containing aldehydes are generated by wet oxidation of human waste and sludge, drying and incineration of activated sludge, heating acid of glass
It is a substance that appears in the exhaust gas from processes such as shell mold casting, which heat-treats organic materials, and is often considered to be the cause of odor pollution. For deodorization as a means of removal, a method of deodorizing by oxidation using hydrogen peroxide, an aqueous solution of sodium chlorate, or ozone has been implemented. However, these S-forming agents are highly concentrated depending on the concentration of aldehyde in the gas! It has the disadvantage that it must be used at different times, and the excess discharge causes secondary pollution. Furthermore, depending on the oxidation conditions, aldehydes may change to organic acids, producing a different kind of bad odor. Furthermore, since the gas temperature is high due to the nature of the process, it has been pointed out that there are cases where the gas is thermally decomposed by l/i by the oxidizing agent, resulting in almost no deodorizing effect.

The present inventors have pursued a deodorizing method that has no odor-reducing effect on aldehydes and is also applicable to high-temperature gases, and as a result of intensive research, we have found that By adding an appropriate amount of glycerin to soda as an absorbing liquid, the inventors achieved the desired objective and completed the present invention.

That is, the present invention is a chemical cleaning and deodorizing method using salivary soda added with glycerin as an absorbing liquid.

A method has already been proposed in which sodium sulfite is used in a chemical solution for cleaning and deodorizing odor gases whose main components are aldehydes. However, it has been shown that the color number of sodium sulfite solution decreases due to gas-liquid contact with air (F Water Works Association Magazine vol. 120. No. 225. 1983/215
(See pages 4-59). Therefore, if this method is applied immediately to a deodorizing device, a large amount of sodium sulfite will be consumed without taking part in the deodorization reaction, making it uneconomical. The deodorizing effect is opaque.

By adding glycerin at a certain degree to an absorbing liquid containing sodium sulfate, it is possible to obtain an odorless effect by lighting it with a high-4 degree odor gas. The /#1 range of added glycerin is 1-4 w/v% as shown in Example 1
The greatest effect can be seen here.

Example 1 Air washing pin (250m7!"d) To an aqueous solution containing approximately 100 ppm of sodium sulfite and acetaldehyde in VC, add #1 volume (il) of glycerin, and add air (
I L/min ) At t3, iNj was blown into the reactor, and the acetaldehyde concentration before and after aeration was measured by gas chromatography, and the relationship between the decomposition rate and glycerin concentration + f was determined as shown in Table 1.

Table 1 It is said that an addition reaction as shown in the following formula occurs between 71 and aldehydes.

This is an equilibrium reaction, so if there is a shortage of sodium sulfite, a reverse reaction occurs and aldehydes are regenerated.

Glycerin has the effect of preventing the oxidation of sodium sulfite, and the higher the glycerin content, the more the prevention effect is promoted, but the decomposition rate of acetaldehyde in Example 1 has an extreme value, and the lateral change of glycerin increases rapidly. does not necessarily match. Therefore, the effect of adding glycerin in the present invention is =
This is not due to the oxidizing effect of ll'u sulfuric acid, but is due to a reaction falsification.It is unclear, but the glycerin in the four dishes acts to prevent the progress of the reverse reaction.

It is thought that there is no such thing.

On the other hand, Kasu l dredged soda is easily decomposed and decomposed by heat, and is heated to 40°C.
Although it is particularly sensitive to the following gases, Example 3vC
As shown, according to the present invention, sodium sulfite decomposes decomposition of sodium sulfite and has a deodorizing effect even on hot gases.

Table 2 shows an example of a wet oxidation treatment of human waste using the Zimmerman process. In Figure 1g1, the exhaust gas was drawn into the absorption tower 1 from the exhaust gas reservoir duct 7 part 13 through orifices 14 and 15 for flow rate 1 law. Absorbent liquid,
Around 1 hour, the pump I pumps the water from the storage tank 5, and while adjusting the flow rate with the flow meter 8, it is dispersed from the top of the packing layer 2 in the absorption tower into the tower, and the filling material is used to collect gas and air for 7 nights. brought into contact. Others, looking at the same figure, 3 is a demister, 14 is a gas outlet, 1
An ipH meter, 12 a manometer, and 6 a valve.

Knowing that the i [transformation condition + r] of the Yue odor apparatus and equipment was as follows, the measurements were performed using the gas chromatography method and the three-point ratio odor bag method.

Processing gas t: 150,71'/, gas column, III [
:1.5m/s, i gas ratio: :2! /7F/, light filling height: L 8 tn, absorption liquid: sodium sulfite 1.3
w/v%, glycerin 3 w/v%, pH 7
Example 3 Activated sludge drying furnace exhaust gas gold, gas temperature after cooling in water washing tower 5
Table 3V shows an example in which the sample was treated at 0° C. using the same deodorizing device as in Example 2, and the aldehyde removal effect was measured by chromatography.

Table 3) In the present invention, the L removal rate of formaldehyde is not necessarily high, but since the formaldehyde detection threshold is close to 'l' p p m, it has little effect on deodorization.

When the surplus of the absorbent discharged from the deodorizing device was mixed with a portion of the cooling water of the washing tower, the deodorizing effect was improved (although not), and most of the remaining sodium sulfate was thermally decomposed.

[Brief explanation of drawings]

Fig. υ1: is a railway diagram showing one of the most difficult routes suitable for carrying out the method of the present invention. 1...Absorption tower 2...Filling material, Zeng 3...Demister-5: (Absorption liquid) circulation storage 1 arm

Claims (1)

[Claims] 1. A chemical cleaning and deodorizing method using an aqueous sodium sulfite solution to which glycerin is added as an absorbing liquid. 2. A claim in which the surplus discharge part of the absorption liquid used in the later stage is reused as the absorption liquid in the previous stage (the method of use 1. 3. The surplus discharge part of the absorption liquid used for deodorization is reused as the absorption liquid in the previous stage). 2. The method of claim 1, wherein the method is reused as part of the cooling water.