JPH01218619A - Dehumidifying agent - Google Patents

Abstract

PURPOSE:To provide an easily reusable inexpensive dehumidifying agent which is large in dehumidification capacity, by depositing copper sulfate on a gypsum carrier. CONSTITUTION:The dihydrate gypsum resulting from a flue gas desulfurization device during desulfurization in calcined gypsum process is heated into a hemihydrate gypsum, to which an aqueous copper sulfate solution is added and, after kneading, this mixture is solidified and heated to form a dehumidifying agent. Hence, the gypsum changes back into a dihydrate in the presence of water, serving as a dehumidifying agent and as a caking agent for a powdery copper sulfate. Since this dehumidifying agent is white when high in dehumidification capacity and presents a blue color characteristic of CuSo4.5H2O at a saturated water adsorbing point, the terminal point of the dehumidification capacity can be judged from changed in the color. It is also made easily reusable by heat treatment.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a new dehumidifying agent, particularly for dehumidifying industrial gases such as Co, laser oscillation medium gas and natural gas, moisture-proof precision machinery, steel materials, etc. Dehumidifying during storage and transportation, drying rooms and clothes boxes,
This product relates to a desiccant used for drying moisture-proof foods (such as biscuits, biscuits, and crackers).

[Conventional technology]

As conventional desiccants, calcium chloride, copper sulfate, zeolite 1-, silica gel, etc. are used.

Calcium chloride is expressed as CaC4.2H20 and is 30
When heated near 0°C, it dehydrates and forms anhydrous calcium chloride (
CaCl2) is used as a dehumidifying agent, but since it is a powder, handling during filling and unloading is inconvenient; There is a drawback that pressure loss is large when contacting gas during dehumidification. Furthermore, because of its deliquescent properties, it is rarely used effectively, and it also has the drawback of causing corrosion when it comes into contact with mechanical parts, which limits its use.

Copper sulfate is usually expressed as CuSO4*5H10, 15
When heated above 0°C, it dehydrates and becomes anhydrous copper sulfate (Cu80n).
) is used as a strong dehumidifying agent, but since it is a powder, it is inconvenient to handle when filling and taking out, and since it is a powder, it is not suitable for dehumidification. When the agent is brought into contact with a gas, it has the disadvantage of a large pressure loss, similar to the case with μsium chloride. However, this material not only has the disadvantage of poor utilization as an absorbent, but also has the problem of being expensive compared to zeolite and silica gel.

In addition, zeolite and silica gel have the disadvantage that they co-adsorb polar substances such as Co in addition to water.

[Problem to be solved by the invention]

In view of the above-mentioned state of the art, the present invention aims to provide a desiccant agent that is inexpensive, has a large dehumidifying capacity, and is easily regenerated.

[Failure to solve the problem]

The present invention is a desiccant agent characterized in that copper sulfate is supported on gypsum.

[Effect]

Gypsum used as a carrier in the present invention is an extremely inexpensive material that can also be obtained by a desulfurization process using the lime plaster method. Also, when this gypsum is heated to over 100 degrees, it changes from industrial water salt (CuSO4-2H!0) to hemihydrate salt (C
aS04.%H,O), and this hemihydrate salt is also restored to industrial water salt in the presence of moisture, so it also acts as a desiccant agent. In addition to this effect, copper sulfate, which is a powder, has the advantage of being effective as a molding binder.

The weight ratio of gypsum to copper sulfate in the desiccant of the present invention is preferably in the range of gypsum:copper sulfate=100:20 to 5o. This is because if copper sulfate is sold in large quantities, the strength will be improved but the dehumidifying effect will be reduced, and if copper sulfate is sold in such large quantities, the dehumidifying effect will be improved but the strength will be reduced. Practically speaking, plaster 1
It is preferred to use copper sulfate in an amount close to 50 parts by weight per 00 parts by weight.

〔Example〕

Below, a conventional dehumidifier containing copper sulfate alone is given as a comparative example.
An embodiment of the desiccant of the present invention will be explained in comparison thereto.

As a comparative desiccant agent, reagent-grade Cu S 04.5H!
The powder of No. 0 was directly heated at -160°C for 3 hours to obtain anhydrous copper sulfate CuSO4. (The scattering temperature of this 5H80 is 150°C.) This was filled into a glass tube, and water-containing air (approximately Q, 42%) prepared by contacting the filled material with water at 30°C was passed through to dehumidify it. I did it. Initially, the air treated with the desiccant contained almost no moisture, but over time, as the moisture absorption capacity decreased, moisture began to remain. The residual concentration of water is Q,
The weight of the desiccant was measured when the moisture content reached 1% by volume, and calculation was made assuming that the theoretical amount of moisture absorbed was up to CuSO4.5H20, and the amount of water absorbed was 23% of the theoretical amount. That is, the filled C
77% of uSO4 was unreacted, and the utilization rate of CuSO4 was poor.

On the other hand, industrial gypsum (Cu) produced from flue gas desulfurization equipment
SO4-2FI, O) was heated at 150°C for 3 hours to obtain gypsum hemihydrate. An aqueous solution previously dissolved in water containing 50% by weight of copper sulfate (CuSO4.5H,O) was mixed with gypsum hemihydrate, thoroughly kneaded, solidified, and heated at 160°C for 5 hours. It was used as a dehumidifier.

As in the comparative example, a dehumidification test was performed using air humidified with 30°C water, and when the reaction rate of CuSO4 was calculated at the point when 0.1% by volume of water remained in the treated gas, the theoretical value was 77.
%Met. That is, the unreacted portion of CuSO4 was 23%, and a significant improvement in the utilization rate of CuSO4 was observed. Even if the gypsum in this desiccant absorbs half of the moisture, the utilization rate is higher than that of copper sulfate alone (comparative example), and the effect of the combination with gypsum can be seen.

This dehumidifying agent is white when its dehumidifying ability is high, and becomes blue, which is characteristic of CuSO4.5 H,O, when moisture is saturated and adsorbed, so it is convenient to indicate when it is time to regenerate.

It was also found that the dehumidification ability was recovered by heat treatment at 160° C. after use to saturation.

〔Effect of the invention〕

The dehumidifying agent of the present invention has a large moisture adsorption capacity, is recyclable, and the end point of dehumidifying ability can be determined by a change in color, so it is an industrially extremely useful dehumidifying agent.

Claims (1)

[Claims] A desiccant characterized by having copper sulfate supported on gypsum.