JPS6345859B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an element for adsorbing and removing adsorbed components such as solvent vapor in a process gas, which exhibits particularly excellent adsorption performance and recovers excellent adsorption performance through desorption and regeneration. The present invention relates to an adsorption element that can be used.

As a relatively new type of adsorption element for removing harmful components from processing gas, adsorption is made by stacking a large number of sheet-like materials containing an adsorbent material such as activated carbon in a wavy or honeycomb shape. element is known. This element has advantages such as a wide effective contact area with the processing gas, excellent removal efficiency, and relatively simple desorption and regeneration processing.

By the way, this regeneration of the adsorption element is usually carried out using heated gas such as heated air or heated nitrogen, or steam, and especially when recovering desorbed components, desorption and regeneration are mainly performed using steam. On the other hand, the adsorption performance of an adsorbent material is often influenced by its water content, and the higher the water content, the lower the adsorption performance. Therefore, it is desirable that the adsorbent material in the adsorption element be kept as dry as possible, and that the relative humidity of the process gas be kept as low as possible. However, even if these conditions can be maintained, the water vapor regeneration as described above is performed, and the moisture content of the adsorbent material increases during the regeneration stage, resulting in a significant drop in adsorption performance. Therefore, in order to recover the adsorption performance after regeneration in a practical sense, it is necessary to dry and remove the moisture in the adsorption material after desorption, and the time and effort required for regeneration is extremely large.

The inventors of the present invention focused on the above-mentioned circumstances, and if they could suppress the adhesion of moisture to the absorbent material as much as possible, and if it did adhere, it could be easily removed, thereby reducing the drying time after regeneration. We believe that the process can be simplified or omitted, and that high adsorption performance can be achieved even when the undried process gas is supplied as is, and we have been conducting intensive research to realize this idea. As a result, it was found that the above object could be successfully achieved by using the adsorption element shown below, and the present invention was finally completed.

That is, the structure of the adsorption element according to the present invention is such that the adsorption element is formed by combining sheet-like materials having adsorption ability to define a large number of gas passages, and in which an aqueous alkali silicate solution or a colloidal silicate solution is applied to the surface in contact with the treated gas. The gist lies in the fact that a porous polymer film with siloxane bonds is formed by adhering and heat-treating the adsorption element, thereby suppressing the adhesion of moisture to the adsorption element and making it possible to easily remove the adhering moisture. do.

In the present invention, a sheet-like material having adsorption ability refers to a sheet-like material containing or attached with an adsorbent material such as powder, granules, or fibers. Specific examples of adsorbent materials include activated carbon, activated alumina, and silica gel. , zeolite, ion exchange resin, clay-based adsorbent, etc. Among these, specific means for obtaining a sheet material with adsorption performance using fibrous activated carbon, for example, include forming it into a sheet shape by itself, or mixing it with fibrous material such as pulp or asbestos. A method of forming the material into a sheet-like material is adopted. In addition, when using a powdery adsorbent material, a method is adopted in which the adsorbent material is suspended together with a fibrous material such as pulp or asbestos and then put into papermaking, or it is attached to the surface of a sheet-like material prepared in advance. A method of manufacturing an adsorption element using this sheet-like material is, for example, as shown in Figs. Apply adhesive and wind up into a roll as shown in Figure 3, or
As shown in the figure, a large number of layers are stacked to define a large number of gas passages to form an adsorption element. When using this element 3, the processing gas G flows in through one opening and flows out through the opening at the other end, but the solvent etc. in the processing gas G is adsorbed during the process of passing through the element 3. It is adsorbed to sexual materials. If the shape, height and pitch of the waves, the length in the gas passage direction, etc. are adjusted appropriately according to the type and amount of processing gas G, harmful components in processing gas G can be almost completely removed. can.

By the way, in this type of adsorption element 3, the adsorption performance decreases rapidly when the amount of adsorption reaches a saturated state, so desorption and regeneration must be performed after that, but if water vapor or the like is used for desorption and regeneration as described above, The adsorption capacity of the adsorption element 3 is significantly reduced. Moreover, in the conventional adsorption element 3, even in the processing stage, the processing gas G
It absorbs the moisture inside, and its adsorption performance quickly decreases.

On the other hand, in the adsorption element of the present invention, a porous polymer film having siloxane bonds formed by the treatment described below is formed on the surface in contact with the processing gas, and its water-repellent action allows water to be absorbed into the adsorption layer. Infiltration is prevented as much as possible. Therefore, even when regenerating with water vapor or the like, adsorption performance does not deteriorate due to moisture absorption, and high adsorption performance is immediately restored by desorption of adsorbed components. Furthermore, even when undried gas is used as the processing gas, no moisture absorption occurs, so the rate of decline in adsorption performance over time is extremely slow. Furthermore, since the adsorption element itself has a water-repellent effect, even if it absorbs some moisture, it can be easily removed with a slight heating, thereby significantly simplifying the regeneration process.

By the way, when forming the water-repellent film on the adsorption element, the adsorption element 3 that has been assembled as shown in Figs. 3 and 4, or the sheet-like material 1 (Fig. With this method, in which the corrugated sheet material 2 (Fig. 2) is impregnated with an aqueous alkali silicate solution or a colloidal silicate solution and then heat-treated, the solution penetrates into the layers of the sheet material constituting the adsorption element. This method is extremely effective because a polysiloxane-based water-repellent porous film is formed on the surface of each adsorbent material. The impregnation rate at this time is not particularly limited, but is most preferably in the range of 2.5 to 50% by weight. However, if it is less than 2.5% by weight, sufficient water repellency will not be exhibited, while if it exceeds 50% by weight, the water repellent layer will become too thick and the adsorption performance will tend to be inhibited.
Also, the heat treatment temperature after impregnation is preferably 50℃ or higher.
A temperature in the range of 100 to 250°C is best; if the heat treatment temperature is too low, the siloxane bond will be insufficient and sufficient water repellency will not be obtained, while if it is too high, it will cause thermal deterioration, especially when the base material is pulp. I don't like it because it has a tendency.

In this case, the greatest feature of the adsorption element of the present invention is that a polysiloxane-based polymer porous film is formed on the surface in contact with the processing gas, thereby imparting water repellency to the adsorption surface. shape and structure,
The desorption means etc. are not limited at all, and can be applied to all known adsorption elements of this type and their improvement elements. Furthermore, the configuration of the processing equipment to which this adsorption element is applied is not limited in any way; it may be a type that performs adsorption, desorption, and regeneration continuously and in parallel, or a type that performs adsorption, desorption, and regeneration in parallel.
This method can be applied to all types of playback that are performed intermittently and alternately.

For example, FIG. 5 is a schematic diagram showing the latter type. That is, adsorption units A and B containing adsorption elements (water-repellent treated) as shown in FIGS. 3 and 4 are arranged in parallel, and each unit A and B is connected to exhaust gas pipes 4a, 4b, Clean gas pipe line 5a,
5b, the desorption steam pipes 6a, 6b and the desorption gas pipes 7a, 7b are connected, and each pipe is provided with a switching valve 4 for alternately switching the pipes.
c, 5c, 6c, and 7c are provided. Further, after the desorption gas line switching valve 7c, a separation device c or the like for separating and recovering the desorbed solvent from the vapor, for example, is arranged as desired.

When the exhaust gas containing harmful components is adsorbed through the exhaust gas pipe 4a, the adsorption unit A, and the cleaned gas pipe 5a, the adsorption unit B uses the pipe 6b.
Desorption and regeneration are performed by the steam supplied from the pump, and these are performed alternately by switching the switching valves 4c, 5c, 6c, and 7c. Then, the gas from the desorption gas pipe 7b is sent to the separator C, where it is separated and recovered from water vapor, or a combustion device is disposed in place of the separator C to burn off the desorbed harmful components.

Therefore, by periodically switching the switching valves according to the adsorption performance (adsorption saturation capacity) of adsorption units A and B, adsorption, desorption, and regeneration can be carried out continuously. Note that the same understanding applies even when three or more adsorption units are used in combination, and the adsorption and desorption/regeneration can also be performed alternately using one adsorption unit.

The adsorption element of the present invention is applied to, for example, the above-mentioned devices, but the feature of the present invention is that the adsorption element is water-repellent treated to prevent performance deterioration due to moisture absorption. ,structure,
All known techniques or techniques that will be developed in the future can be applied to the adsorption/desorption operation method.

The present invention is roughly constructed as described above, and its effects can be summarized as follows.

Since water repellency is imparted by the porous polysiloxane-based polymer film, the adsorption performance hardly deteriorates even when water vapor or the like is used as the regeneration gas. Furthermore, even when a undried processing gas is used, the adsorption performance does not deteriorate, and adsorption performance corresponding to the saturated adsorption capacity can be ensured.

The polysiloxane film has excellent heat resistance as well as water repellency, and prevents moisture softening of the adsorption element and also suppresses thermal deterioration. Therefore, the number of repeated uses, that is, the life span can be greatly extended.

A polysiloxane film can be easily formed by impregnating an adsorption element or a sheet-like material that is a component thereof in a silicate colloid solution or the like and heat-treating it, so that the manufacturing burden is small.

Since the shape and structure of the adsorption element are not limited at all, the present invention can be applied to any adsorption element of this type without any inconvenience.

Next, examples of the present invention will be shown, but like the embodiments described in the claims, the following do not limit the present invention, and can be appropriately modified in accordance with the spirit of the above and below. and all of them are included within the scope of the present invention.

Example 1 Activated carbon fiber 70 using cellulose fiber as a precursor
30 parts by weight of asbestos fibers and a very small amount of polyvinyl alcohol fibers were mixed and paper was made using a normal wet paper making method to obtain activated carbon fiber-containing paper having a basis weight of 50 g/m ² and a thickness of 0.25 mm. Using this paper, a single-sided corrugated cardboard sheet with a pitch of 3.1 mm and a wave height of 2.0 mm was produced. This was immersed in a 20% silica sol aqueous solution for 10 minutes, drained, and heat-treated at 140°C for 10 hours to make it water repellent (amount of silicic anhydride adhered: 45
weight%).

This cardboard sheet was cut into pieces of 40 cm wide and 45 cm long, and 200 sheets each were stacked as shown in Figure 4 to obtain two adsorption elements (40 cm x 40 cm x 45 cm). These adsorption elements were filled in each adsorption device, arranged in parallel as shown in FIG. 5, and subjected to alternating adsorption/desorption processing.
The processing gas used was air containing 500 ppm toluene, which was flowed into one tank for 7 minutes at a speed of 1.5 m/sec across the cross section of the stack, and 120°C steam was fed into the other tank for 4 minutes for regeneration. I did this. Further, the desorbed toluene was separated and recovered from the condensed water using a separator.

As a result of continuous operation while repeating this operation,
92% of the toluene in the treated gas was adsorbed and removed, and almost all of this toluene could be recovered from the condensed water. Further, this treatment was continued for 50 hours, but almost no decrease in treatment efficiency was observed.

Comparative Example 1 The operation of the adsorption element and the adsorption/desorption test were conducted in the same manner as in Example 1 except that the silica sol treatment was omitted. As a result, it was confirmed that 92% of toluene could be removed initially, but the removal efficiency significantly decreased over time, dropping to 75% after 5 hours and 50% after 20 hours. This is thought to be because the adsorption element became wet due to the regeneration treatment with water vapor, resulting in a decrease in adsorption performance. Moreover, it was confirmed that after 20 hours of operation, the adsorption element absorbed a large amount of water and became soft, indicating that it was on the verge of losing its shape retention.

Example 2 The activated carbon fiber-containing single-sided corrugated sheet used in Example 1 was rolled up to a width of 300 mm, an outer diameter of 130 mm, and an inner diameter of 40 mm to produce a cylindrical adsorption element. This was immersed in a 15% aqueous solution of sodium silicate for 15 minutes, thoroughly drained, and then heat treated at 140°C for 10 hours to make it water repellent.

Fill this element into an adsorption device and use toluene.
Toluene is adsorbed and removed by flowing air containing 150 ppm at a superficial velocity of 1.5 m/sec. After the adsorption capacity of the element is saturated, water vapor at 120°C is flowed for 30 minutes to perform desorption regeneration. This adsorption/desorption process was repeated 50 times, but no change in the shape of the adsorption element was observed.
In addition, the initial leakage is 3ppm, and the adsorption zone thickness is as short as 30cm.
This deterioration in adsorption performance over time was hardly observed.

On the other hand, when an adsorption/desorption test was conducted in the same manner as above except that the sodium silicate treatment was omitted, the amount of moisture adsorbed by the element reached 150% after 5 repetitions, and the thickness of the adsorption zone could not be measured accurately. Also, regarding the adsorption performance, leakage of 30 ppm or more was observed from the initial stage of adsorption. Furthermore, the shape retention of this adsorption element was significantly reduced, and it was easily deformed by a slight external force.

[Brief explanation of the drawing]

Figures 1 to 3 are sketches showing an example of how to assemble an adsorption element, Figure 4 is a sketch showing another adsorption element, and Figure 5 is an explanatory diagram illustrating an adsorption/desorption treatment method using the adsorption element of the present invention. be. 1... Sheet-like material, 2... Single-sided corrugated sheet material, 3... Adsorption element, A, B... Adsorption unit,
4a, 4b...Exhaust gas pipe line, 5a, 5b...Clean gas pipe line, 6a, 6b...Steam pipe line for desorption, 7
a, 7b... Desorption gas pipe line, 4c, 5c, 6c,
7c...Switching valve.

Claims (1)

[Claims] 1 Siloxane produced by adhering an aqueous alkali silicate solution or a colloidal silicate solution to the surface in contact with the treated gas and heat-treating it in an adsorption element formed by combining sheet-like materials with adsorption ability to define a large number of gas passages. An adsorption element with excellent adsorption and desorption performance characterized by forming a porous polymer film containing bonds.