JPH0966213A - Adsorption element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorption element with improved heat transfer efficiency adopting an indirect heating (cooling) method to prevent the generation of a large amount of waste water by the condensation of steam as the adsorption element to be used for the adsorption separation and desorption recovery of a gas component. SOLUTION: An adsorption element 1 with a structure in which a heat transfer body 3 for heating or cooling is inserted into an adsorbent layer has the structure in which, when the heat transfer body 3 is inserted, a heat transfer medium such as gauze 4 which is brought into contact with the heat transfer body 3 is inserted together. For the adsorption element in which the adsorbent layer 2 is formed cylindrically around a core material to make gas flow in the radial direction of a cylinder, the heat transfer body 3 and the heat transfer medium in contact with it are arranged concentrically in one or more lines. Therefore, by inserting the heat transfer medium such as a gauze 4 together with the heat transfer body 3 keeping in contact with it, an effective heat transfer area is increased to promote a heat transfer effect, and especially heating efficiency is elevated during adsorption regeneration, improving the removal recovery performance of a solvent, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of an adsorption element used for separating gas or vapor components by an adsorption operation.

[0002]

2. Description of the Related Art In various factories, air or other gases containing solvents or other harmful components are generated,
Purification by removing the solvent and the like from the generated gas is important in terms of environmental measures, and it is also an important process to separate or remove dilute components from various mixed gases.
The adsorption operation is particularly effective for the separation of such gas components and has been applied in many fields from the past. In the adsorption operation, the components to be separated are adsorbed on the adsorbent, and then the adsorbed components are desorbed by blowing steam into the adsorbent,
It is generally practiced to re-adsorb the adsorbent that is recovered and regenerated by desorption.

However, this method has a problem that a large amount of condensed water of steam is generated during desorption and waste water is generated, or decomposition of the recovered component is promoted by contact with the steam. Therefore, in recent years, in the adsorption treatment operation, A desorption method other than such direct blowing of water vapor is desired. Desorption mainly includes thermal desorption by heating the adsorbent and decompression desorption that lowers the pressure than during adsorption.In either method, it is necessary to give the adsorbent latent heat of desorption necessary for desorption. , Heating means for that is indispensable.

As a desorption method which does not depend on the blowing of steam, conventionally, a method of passing a heating gas instead of steam, a method of directly heating the adsorbent layer with electromagnetic waves such as microwaves, or a method of heating the adsorbent layer such as activated carbon with steam is used. There are methods such as embedding tubes and sheet heaters, but in the heating gas flow method that is generally practiced, the desorbed components are diluted by the heating gas, so there is a limit to the degree of concentration, and gas concentration is possible. However, it may be difficult to recover. In addition, the electromagnetic wave heating method, the cost of the electromagnetic wave generator is high,
It may be difficult to uniformly heat the adsorbent.

Further, a method of embedding a heater in the adsorbent layer has been found for some time, and is disclosed in, for example, Japanese Patent Publication No. 2-48287.
JP-A-1-242121 and 266832, JP-A-4-2641
It is also disclosed in 341316 and 341317. However, since the adsorbent is generally porous and poor in heat transfer, it is customary that such an indirect heating method requires a long time for heating for desorption and uniform heating is difficult.
In the case of the continuous adsorption / desorption method, a large amount of adsorbent is required to secure the adsorption capacity during the desorption period, so that there is a problem that the apparatus becomes large and the manufacturing cost is high. As described above, each of the methods has various problems.

[0006]

The present invention adopts a method of embedding a heat transfer material in an adsorbent layer as a method of heating or cooling the adsorbent without directly contacting the adsorbent with water vapor. It is an object of the present invention to provide an adsorption element which solves the above-mentioned problems, is simple in structure and manufacture, and has high thermal efficiency.

[0007]

As a result of researches conducted by the present inventors, in an adsorption element having an adsorbent layer in which a heat transfer body is inserted, adsorption of a structure in which a heat transfer medium is inserted in contact with the heat transfer body More specifically, by adopting the element, the adsorbent layer is formed in a cylindrical shape around the core material in order to allow the gas to flow in the radial direction of the cylinder, and the heat transfer body is concentrically formed on the adsorbent layer. It is possible to solve the above-mentioned problems by adopting an adsorption element having a structure in which one or more rows are inserted in a row and the heat transfer medium is inserted in contact with the heat transfer body row. is there.

Here, the heat transfer element means a heating / cooling means having a fixed shape, and for example, a heat transfer tube of a system in which a heat medium fluid is flown into the tube, or a nichrome wire itself generates heat. A heating wire or the like is used. In addition, the heat transfer medium
It means a means for transmitting the heat of the heat transfer material to the adsorbent, and a material having good thermal conductivity such as a wire mesh is used.

As an aspect of the present invention, an adsorbing element in which a heat transfer body and a heat transfer medium which are in contact with each other are embedded in advance in an adsorbent layer is manufactured, and one or a plurality of such adsorbing elements are mounted in a prepared container. Generally, the above-mentioned one is used as the adsorption tower, but in addition to that, the heat transfer medium and the heat transfer medium which are in contact with each other may be embedded in the adsorbent layer of the adsorption tower directly filled with the adsorbent. As a form of the adsorbent layer, a cylindrical gas is allowed to flow in the radial direction,
This is efficient because the cross-sectional flow area of the gas per unit volume of the adsorption element can be increased. In that case, the adsorbent layer is arranged in a cylindrical shape around an appropriate core material, and the heat transfer body and the heat transfer medium in contact with the heat transfer medium are concentrically inserted in one or more rows in the adsorbent layer.

A conceptual diagram of the adsorption element of the present invention is shown in FIG. It is conceptually shown that the heat transfer body 3 and the heat transfer medium 4 in contact with the heat transfer body 3 are embedded in the adsorbent layer 2.

An example of an embodiment of the adsorption element of the present invention is shown in FIG. A pair of disk-shaped end plates 5 are fixed and arranged at both ends of a cylindrical core member 6 near the center thereof. This core material forms the core of the adsorption element, around which sheet-like activated carbon fiber as an adsorbent is wound up and laminated to form an adsorbent layer 2 in a cylindrical shape. Then, for each constant thickness of the adsorbent layer, a heat transfer tube array 7 for heating / cooling is inserted as a heat transfer member in a concentric circle shape. As shown in FIG. 2, these heat transfer tube rows are preprocessed so that one heat transfer tube is meandered at a constant pitch and further along the peripheral surface of the adsorbent layer. A wire net 4 as a heat transfer medium is inserted in contact with these heat transfer tube rows. The wire nets are provided on both surfaces of the heat transfer tube array, that is, on the inner peripheral side and the outer peripheral side, respectively, in contact with the heat transfer tubes.

In practice, a sheet-like activated carbon fiber such as activated carbon felt is laminated to a certain thickness, a wire mesh is first wound on it, and a heat transfer tube is circumferentially arranged in contact with the wire mesh. Then, wind a wire mesh as before. A sheet-shaped activated carbon fiber is further laminated on the outer side thereof. These heat transfer tube rows are provided in the required number of stages according to the thickness of the entire adsorbent layer. In this way, an adsorption element having an adsorbent layer having a constant thickness and a row of heat transfer tubes is formed.

In this adsorption element, the gas is circulated in the radial direction from the outer peripheral surface toward the core material or vice versa. The heat transfer body and the heat transfer medium in contact with it are usually inserted so as to be embedded in the cylindrical adsorbent layer, but a part thereof may be provided just outside the core material, that is, on the innermost layer surface of the adsorbent layer. is there. This is because when the purge gas for desorption regeneration is caused to flow from the inner layer of the cylindrical adsorbent layer toward the outer layer, the heat desorption is particularly effective on the inner layer side. Further, in such a case, a simpler structure can be obtained by configuring the core material itself with the heat transfer body and the heat transfer medium in contact with it.

When the heat transfer medium and the heat transfer medium are inserted into the adsorbent layer, the structure is generally complicated and the production is difficult, and as a result, the exchange of the adsorbent is also difficult. However, in the present invention, as described above, after forming the adsorbent layer having a certain thickness, the prefabricated heat transfer tube and the wire net are set, and the adsorbent layer is further formed thereon repeatedly as many times as necessary. By adopting the mode, the work of embedding the heat transfer body and the heat transfer medium in contact with the heat transfer body in the adsorbent layer becomes extremely easy, and the adsorption element having the adsorbent layer having good heat transfer property can be relatively easily manufactured. .

Further, as shown in FIG. 3, the sheet-like activated carbon fiber 8 and the wire net 4 are superposed and rolled up in a spiral shape, and the heat transfer body 3 prefabricated at a constant thickness is set and further superposed sheet. It is also preferable that the activated carbon fiber and the wire mesh are wound up to form an adsorption element having an adsorbent layer in which the sheet-shaped activated carbon fiber and the wire mesh are alternately laminated. In this case, the insertion ratio of the heat transfer medium can be changed by adjusting the numbers of the sheet-like activated carbon fibers and the wire mesh at the time of winding.

The adsorbent used in the present invention is generally activated carbon, but other than that, any adsorbent capable of adsorbing gaseous substances such as zeolite, activated alumina and silica gel can be used without limitation. The form of the adsorbent may be granular or fibrous, and sheet-like activated carbon fiber is most preferable. The activated carbon fiber has a much higher adsorption rate than other adsorbents, and the adsorbent utilization efficiency is high, so the device becomes compact, and the use of sheet-shaped activated carbon fiber makes the adsorbent layer It becomes easy to control the packing density of, and it is possible to manufacture adsorption elements with extremely uniform performance characteristics. As a preferred structure of the adsorbent layer of the adsorption element of the present invention, a sheet-like activated carbon fiber is used as an adsorbent, and this is wound up in a spiral shape while adjusting the tension of the sheet around the core to obtain a constant packing density. With this, an adsorbent layer having an arbitrary thickness can be easily formed.

As the sheet-like activated carbon fiber, the felt-like one is the most general and cheap, but other than the woven fabric,
Breathable sheet, such as knit or braid,
In addition, any of them can be used as long as the shape can be maintained when wound up. In particular, the woven or knitted structure can increase the bulk density of the sheet-like activated carbon fiber and increase the adsorption capacity per unit volume, so that the entire adsorption device can be made compact. When a felt-like sheet-like activated carbon fiber is used, for example, a felt having a thickness of 3 mm and a basis weight of 100 g / m ² is rolled up to a thickness of 15 to 20 cm to form an adsorbent layer.

The heat transfer body inserted in the adsorbent layer is for heating the adsorbent layer, or for heating and cooling the adsorbent layer. Generally, a metal heat transfer tube through which a heat transfer fluid flows is used. To be done. When desorbing and regenerating the adsorbent layer, steam is usually used as a heating medium fluid for heating, and when adsorbing and cooling the adsorbent layer after desorption regeneration, cooling water is passed instead of steam. Further, a heat pipe for exchanging heat with the outside may be applied as the heat transfer tube. Further, when only heating is required, an electric heater can be used as the heat transfer body. Copper is generally used as the material of the heat transfer material from the viewpoint of thermal conductivity and corrosion resistance, but other materials such as stainless steel,
Brass or the like can also be used.

The heat transfer medium provided in contact with the heat transfer body is for uniform and rapid heat transfer from the heat transfer body to the adsorbent layer, and for that purpose, the material is heat conductive. Copper, stainless steel and the like having good performance are suitable, but copper is most preferable. In addition, as its structure, wire mesh, punching plate,
Examples thereof include those obtained by processing fine metal wires into a web shape. When using a wire net, a wire with a large diameter and a fine opening is suitable from the viewpoint of thermal conductivity, but it is also necessary to consider the heat capacity and ventilation resistance, and also considering workability at the time of manufacturing etc. The one with a different structure is selected. Generally, 1-20
A mesh, preferably 4-18 mesh, and more preferably 8-16 mesh is used. When it exceeds 20 mesh, the pressure loss cannot be ignored. From the viewpoint of pressure loss, 18 mesh or less is preferable, and 16 is more preferable.
Below the mesh. If it is less than 5 mesh, the desired heat transfer effect cannot be obtained.

The adsorption element of the present invention is used, for example, in an adsorption device for solvent recovery as shown in the flow chart of FIG.
Here, the adsorption element 1 is incorporated in the adsorption tower 9 (9A and 9B). While one of the two adsorption towers is in the adsorption step of adsorbing the solvent in the gas to be treated, the other adsorption tower is in the desorption step of desorbing and condensing and recovering the adsorbed solvent under heating and reduced pressure. These steps are repeated alternately in the tower. When the solvent is flammable, the desorption process is performed under N ₂ gas atmosphere, and the uncondensed gas in the condenser is recycled to the gas to be treated.

[0021]

EXAMPLE Using the apparatus shown in the flow chart of FIG. 4, 25 ppm of solvent (isopropyl alcohol) containing 2000 ppm was used.
Air at 50 ° C. and 50 RH% was treated at a rate of 5 Nm ³ / min. The adsorbent in the adsorption tower is made of activated carbon fiber felt, and the felt having a thickness of 3 mm and a basis weight of 100 g / m ² is spirally laminated to have an inner diameter of 100 mm and an outer diameter of 400 m.
The heat transfer tube is a cylindrical type with a height of m and a height of 450 mm, and the heat transfer tube is inserted in the vicinity of the core and at the positions of 160 mm and 280 mm in diameter. A 4-mesh copper wire mesh having a wire diameter of 0.8 mm, a 8-mesh copper wire mesh having a wire diameter of 0.8 mm, or a 16-mesh copper wire mesh having a wire diameter of 0.8 mm was inserted. The average flow velocity of the processing gas in the adsorbent layer is set to about 0.3 m / sec,
The adsorption time for one cycle was 15 minutes.

First, the solvent-containing air is sent to the adsorption tower and passed through the adsorption element, and the cleaned air is discharged into the atmosphere. (Adsorption step) After the adsorption step is completed, the inside of the adsorption tower is evacuated to a reduced pressure, and then 150 N is introduced into the heat transfer tube while purging with N ₂ gas as a carrier gas.
Heat through steam at 5 ° C., 5 kg / cm ² pressure. The decompression degree in the tower during desorption was 50 Torr. The solvent removal rate from the adsorbent layer and the average temperature of the adsorbent layer were measured when the above-mentioned four kinds of wire nets were used and when the wire net was not used (Comparative Example). The results are shown in Table 1.

[0023]

[Table 1] (# In the table indicates the number of meshes)

In all cases where the wire net is used, the average temperature of the adsorbent layer is higher and the solvent removal rate is better than when not used. Although not shown in the table, it has been confirmed that the use of a wire net is significantly superior in terms of temperature uniformity in the adsorbent layer. It seems to have contributed to the improvement.

[0025]

EFFECTS OF THE INVENTION The adsorption element of the present invention does not directly contact the adsorbent with water vapor, so that a large amount of drainage is not generated, and since the adsorbent element has an excellent heat transfer effect, it efficiently heats or cools the adsorbent layer. As a result, the solvent and the like in the gas can be efficiently removed and concentrated and recovered. Furthermore, the structure is simple and the manufacture is easy.

As described above, attempts to insert a heat transfer material into the adsorbent layer have been made conventionally, but since the porous adsorbent has extremely poor thermal conductivity, it is difficult to heat the transfer material. The cooling effect is limited to the vicinity of the heat transfer body, and as a result, the temperature rise or cooling of the adsorbent is non-uniform and time-consuming, and the desorption efficiency is poor, and the performance of the adsorption device using such a method is low. It was usually not good. In the adsorbing element of the present invention, the heat transfer area of the heat transfer body is dramatically increased by inserting a heat transfer medium having good heat conduction such as a wire mesh in contact with the heat transfer body into the adsorbent layer. A very good heat transfer effect can be obtained. Such an effect is remarkable not only during desorption under normal pressure, but especially during desorption under reduced pressure. That is, under reduced pressure, in addition to the poor heat conduction of the adsorbent itself, the poor heat transfer due to the dilution of the gas itself, which is another heat transfer medium, is overlapped, so that heat transfer acceleration by the adsorption element of the present invention is promoted. It seems that the effect is remarkable.

[0027]

[Brief description of drawings]

FIG. 1 ((1a) and (1b)) is a conceptual view of an adsorption element of the present invention, (a) is an overall cross-sectional view, and (b) is an assembled view of an adsorbent layer.

FIG. 2 ((2a), (2b) and (2c)) is a view showing a cylindrical adsorption element which is one of the embodiments of the adsorption element of the present invention, where (a) is an overall view and (b) is FIG. 3 is an assembled view of the inside of the adsorbent layer, and (c) is a sectional view in the radial direction.

FIG. 3 shows an example of an adsorbent layer having a structure in which a sheet-like activated carbon fiber and a wire net are overlapped and rolled up in a spiral shape, which is another embodiment of the adsorption element of the present invention.

FIG. 4 shows a flow example of an apparatus for performing solvent recovery using the adsorption element of the present invention.

[Explanation of symbols]

1. Adsorption element 2. Adsorbent 3. Heat transfer body 4. Wire mesh 5. End plate 6. Core material 7. Heat transfer tube 8. Sheet-shaped activated carbon fiber 9 (9A and 9B). Adsorption tower 10. fan
11. Decompression pump 12. Condenser 13. Solvent recovery tank 14.
Gas to be treated 15. Clean gas 16. Steam 17. N ₂ gas

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Matsuhiro Kimura 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd.

Claims (9)

[Claims] 1. An adsorption element having an adsorbent layer in which a heat transfer body is inserted, wherein a heat transfer medium is inserted together with the heat transfer body in contact therewith. 2. An adsorbent layer is formed in a cylindrical shape around a core material to allow gas to flow in the radial direction of the cylinder, and heat transfer elements are concentrically inserted in one or more rows. Adsorption element according to claim 1, characterized in that 3. The adsorption element according to claim 1, wherein the adsorbent is activated carbon fiber. 4. The adsorption element according to claim 1, wherein the heat transfer medium is a wire mesh. 5. A sheet-shaped adsorbent and a heat transfer medium are stacked on each other and wound up in a spiral shape to form a structure in which an adsorbent layer and a heat transfer medium layer are alternately laminated. The adsorption element according to any one of claims 2 to 4. 6. The heat transfer body according to claim 2, wherein the heat transfer body is directly arranged around the core material, in addition to being embedded in the adsorbent layer. Adsorption element. 7. The adsorption element according to claim 2, wherein the core material is composed of a heat transfer body and a heat transfer medium in contact with the heat transfer body. 8. The adsorption element according to any one of claims 1 to 7, wherein the heat transfer body is composed of a heat transfer tube through which a heat transfer fluid can be passed. 9. The adsorption element according to claim 1, wherein the heat transfer member is an electric heater.