JPS61245822A - Removal of sulfur dioxide - Google Patents

Abstract

PURPOSE:To remove SO2 with high efficiency by a perfect dry system without generating a problem of waste water treatment, by passing exhaust gas containing SO2 through an accumulation bed or packed bed comprising a mixture of calcium hypochlorite and slaked lime mixed at a specific ratio. CONSTITUTION:Powdery or molded Ca(OCl)2 and Ca(OH)2 are mixed in a Ca wt. ratio of 0.05-20 and diatomaceous earth is further added to the resulting mixture to form a dry absorbent bed 1 on a support 2 and SO2- containing exhaust gas G1 is passed through said bed. SO2 in the exhaust gas is oxidized by Ca(OCl)2 and simultaneously immobilized in a CaSO4 form by Ca(OH)2 to be removed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for removing sulfur dioxide gas.

[Conventional technology and its problems]

Methods for removing sulfur dioxide gas from waste residue can be broadly divided into ① wet method and ② dry method. The wet method.

Calcium hydroxide (Ca(on)t)% Calcium carbonate (CaCO,), Magnesium hydroxide (Mg(OH)t)
The sulfur dioxide gas is neutralized and absorbed by a scrubber using a slurry of hydroxide or an aqueous solution of hydroxide (NaOH) as an absorbent, and then transferred to the source side where it is fixed. Although this method is effective and can be expected to have a sulfur dioxide gas removal rate of 90% or more, there is a problem in that wastewater remains to be treated after the sulfur dioxide gas is absorbed, making the treatment system complicated.

On the other hand, dry methods include (1) activated carbon adsorption method and (2) CaC0° high temperature injection method (requires an atmosphere of 5°00 to 600'C or higher). Activated carbon adsorption method removes exhaust gas containing sulfur dioxide by approximately 2
00c, under gas temperatures below.

It passes through an activated carbon layer and adsorbs sulfur dioxide gas on the activated carbon to remove it, and a high sulfur dioxide removal rate of 90% or more can be expected.

However, since the activated carbon that has adsorbed sulfur dioxide gas needs to be regenerated and reused, it is necessary to treat the wastewater generated during activated carbon regeneration, making the overall system complex.

Next, the high-temperature injection method of CaC0, is calculated using the following formula (1)%
It is thermally decomposed to CaO at a high temperature of % or more, and the CaO reacts with sulfur dioxide gas at high temperature in an oxygen atmosphere to form calcium sulfate [CaSO4], which fixes sulfite scum.

Reaction formula CaC0,--CaO+CO,...-
(1) CaO+SO*+ 2 0t C”SO
4...t2'caso, is a dust collector (for example,
? It is a so-called completely dry method, and has the great feature of being able to remove sulfur dioxide gas. However, there is a problem in that it is difficult to obtain a high removal rate. Also.

This method has the constraint of a high-temperature atmosphere of 500 to 6,000 or higher, and has the disadvantage that it cannot be as effective in a low-temperature atmosphere.

[Child actor to solve problems]

The present invention is characterized in that sulfur dioxide gas is removed by passing sulfur dioxide gas-containing exhaust gas through a deposited layer or a packed bed formed by mixing calcium hypochlorite and slaked lime with a calcium weight ratio in the range of 0.05 to 20. This method is used to remove sulfur dioxide gas.

Here, 1. The dry absorbent for removing atomite scum by the method of the present invention is composed of slaked lime and calcium hypochlorite, and is available in powder form and molded form (cylindrical form).

Any spherical shape is fine. ) can be used. When used in powder form, the particle size of the powder is 1 to 1000p, preferably 1
0 to 100 II is suitable. When used for molding, 1 to 50 m, preferably 3 to 20+s, is appropriate. The basis for these numerical limitations is to effectively and sufficiently remove sulfur dioxide gas. In addition to the above-mentioned absorbent components, other components (for example, alumina, silica, etc.) may be added in consideration of air permeability, adhesion, and prevention of moisture absorption, regardless of whether the absorbent is used in powdered or molded form.

Silica alumina, zeolite, diatomaceous material.

Perlite, feldspar, white clay, etc.) can also be added.

The mixing ratio of calcium hypochlorite and slaked lime is such that the weight ratio of calcium is 0.05 to 20.0 to effectively and sufficiently remove sulfur dioxide gas. Preferably, it is appropriate to set it in the range of 0°1 to 2. ing. In the case of the powder dry absorbent layer 1, when the waste gas G1 containing sulfite gas passes through the powder dry absorbent layer 1, sulfur dioxide gas is absorbed and removed. 2 in the figure is a powder support. As the powder support 2, a glass fiber filter, a metal fiber filter, a ceramic filter, etc. can be used. In the case of the shaped dry absorbent layer 3, when the exhaust gas G containing sulfite scum passes through the shaped dry absorbent layer 3, the sulfite scum is absorbed and removed.

In the figure, 4 is a molded absorbent support. As the shaped absorbent support, wire mesh, punched metal, etc. can be used.

When the sulfur dioxide gas in the exhaust gas passes through each of the absorbent layers 1 and 3T, it is oxidized to primary calcium chlorite by the reaction of the linear equation (31, (4), and at the same time, the sulfur dioxide gas is converted into slaked lime in the oxidation field. is fixed in the form of calcium sulfate.

2SO@ + Ca (0CII) t →2 S
Os +C"C6t"・(31So @ 10Ca (
OH) * ” Ca So 4 + H! O-”・
(4 [Operations and Effects of the Invention] According to the method for removing sulfur dioxide gas according to the present invention.

A deposited layer or packed layer of mixed powder or molding material of slaked lime (main component Ca(OH)t) and calcium hypochlorite (Ca(OC6)t) is formed, and exhaust gas containing sulfur dioxide gas is passed through this layer. This method can remove sulfur dioxide gas with high efficiency without the problems of wastewater treatment, and in a completely dry manner.

〔Example〕

The mixing ratio of calcium hypochlorite with an average particle size of 1811 and slaked lime with an average particle size of 15μ is 2 in terms of calcium weight ratio.
= 8 (ie 0.25), diatomaceous earth having an average particle size of 207 J was added in an amount of 10% by weight to form a cake layer on the glass fiber filter to a thickness of about 10 ml. When air containing 1,100 ppm of sulfite sludge was flowed at a flow rate of 1 cm/s through the powder absorption layer consisting of a cake layer, the sulfite sludge concentration behind the powder absorption layer reached 7 ppm one hour after the first gas pass. This was confirmed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the structure of a powdery dry absorbent layer, and FIG. 2 is an explanatory diagram showing the structure of a molded dry absorbent layer. l... Dry absorbent layer, 2... Powder support, 3...
Molded dry absorbent layer, 4... Powdered dry absorbent layer, G1
...Exhaust gas containing sulfite residue. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1■ Figure 2↓

Claims (1)

[Claims] A sulfur dioxide gas characterized in that sulfur dioxide gas is removed by passing sulfur dioxide gas-containing exhaust gas through a deposited layer or a packed bed formed by mixing calcium hypochlorite and slaked lime with a calcium weight ratio in the range of 0.05 to 20. Removal method.