JPH01199621A - Adsorber for gas having very low concentration - Google Patents

Abstract

PURPOSE:To reduce the number of gas adsorption rotors by forming two or more adsorption zones, one precooling zone and one or more regeneration zones in each of the rotors having small through holes from one end of the cylinder to the other end in accordance with the turning of the rotor. CONSTITUTION:Air TA to be treated is sent by a fan 6 to the first adsorption zone 2 of a cylindrical honeycomb rotor 1 impregnated with LiCl, etc. The sent air is dehumidified, passed through a cooler 10, introduced into the second adsorption zone 3 and dehumidified again. The rotor 1 turns and transfers successively from the adsorption zones 2, 3 to the regeneration zone 5. Part of the dehumidified air passed through the precooling zone 4 is heated with a heater 8 and passed through the regeneration zone 5 to desorb the adsorbed moisture and to regenerate the adsorbent. The rotor 1 in the zone 5 returns to the adsorption zones 2, 3 through the precooling zone 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses a rotor having a large number of small holes to reversibly absorb or adsorb (hereinafter referred to as sorption) moisture and other active gases (hereinafter referred to as gases). It is formed of a sheet containing a sorbent, and a processing gas and a desorption gas are passed through the small holes alternately, and the gas is removed by sorption, especially a gas containing an ultra-low concentration gas, such as an ultra-low concentration gas. It concerns hundreds of ultra-low concentration gas machines that obtain air with a low dew point.

Conventional technology A rotor with many small perforations, that is, a honeycomb rotor, is molded using a dehumidifier that absorbs moisture, and two such rotors are used, and the gas to be treated is passed through the first rotor to dehumidify it. After that, it is cooled and passed through the second stage rotor for further dehumidification, and the regeneration gas is passed through the second stage rotor's regeneration zone and heated.
A method for obtaining ultra-low humidity gas with a dew point of -80 DEG C. or lower by passing the gas through the regeneration zone of the rotor in each stage is disclosed in Japanese Patent Laid-Open No. 61-71821.

Problems to be Solved by the Invention In the above method, two dehumidifying rotors are operated in parallel, and the structure is complicated because two rotor drive devices, piping, seal plates, etc. are also required. It requires a large installation area, requires complicated maintenance, and inevitably increases both manufacturing costs and operating costs.

Means for Solving the Problems The present invention eliminates the above-mentioned drawbacks by providing a honeycomb rotor impregnated with a gas sorbent or having a gas sorbent on its surface and formed to have a large number of small holes. The rotor is separated by sectors provided in the casing so that each sector of the rotor functions sequentially as a first stage loading zone, a second stage loading zone, a precooling zone, and a desorption zone. It is designed to perform stepwise sorption. The number of stages of the sorption zone and desorption zone may be further increased, and the zones may be divided into a first stage, a second stage, a third stage, etc. in the direction opposite to the rotational direction of the rotor.

Examples Below, as examples, we will introduce a rotor (special) in which silica/alumina/erogel, which has normal moisture adsorption performance, and synthetic zeolite, which has extremely high moisture adsorption performance for low-humidity air, are synthetically bonded to a honeycomb-like matrix made of non-combustible paper. Gansho 62
-145873) will be described with reference to the drawings.

A low-density paper mainly composed of Ia-free #a fibers is formed to obtain a single-wave molded body, and this single-wave molded body is wound and laminated to form a matrix in which many small holes pass through both end faces. Then, the matrix was impregnated with a dispersion of synthetic zeolite powder dispersed in an aqueous water glass solution, and after drying, it was immersed in an aqueous magnesium salt solution to generate a hydrogel of magnesium silicate through the reaction between the water glass and the magnesium salt, which was then washed with water and dried. A dehumidifying rotor in which synthetic zeolite and magnesium silicate aerogel are integrally bonded to a matrix is obtained. In this dehumidifying rotor, the magnesium silicate erogel acts as a gas adsorbent with normal gas adsorption performance, and the synthetic zeolite acts as a gas adsorption agent with extremely high gas adsorption performance for gases with low gas concentration.

The sectors S shown in FIG. 2 are attached to both end faces of this rotor l, and as shown in FIG. Divided into stage desorption zones 6, each zone is equipped with a fan 7 for introducing processed air, a fan 8 for supplying air, a heater 9 for heating regenerated air,
Regeneration air introduction fan 1O1 Processed air cooling heat exchanger 1
1 is an ultra-low concentration gas adsorption machine with piping as shown in the figure. In addition, to give an example of the width of each zone, that is, the central angle,
Stage adsorption zone 130°, second stage adsorption zone 95°,
They are a pre-cooling zone 45'', a first desorption/desorption zone 45@, and a second desorption/desorption zone 45''.

To explain the process of dehumidifying the working air of the invention as an example, the treated air to be dehumidified is transferred to the first stage adsorption zone 2 of the rotor l by the fan 7.
and is then dehumidified, preferably in a cooling heat exchanger 11.
After being cooled by the cooling water 12 through the cylinder, the cylinder enters the two-pronged suction zone 3 and performs the second dehumidification process, obtaining dehumidified air with an ultra-low dew point.
Supply as.

To explain the process of dehumidifying the rotor, that is, regenerating it, the pre-cooled air, preferably a part of the dehumidified air SA obtained in the dehumidifying process described above, is first passed through the pre-cooling zone 4 to pre-cool the rotor, and then the regenerated air heater 9 is used to heat the rotor. After heating the air to 180°C and passing it through the first stage desorption zone 5 as high-temperature, low-humidity regeneration air RA to desorb the moisture adsorbed on the rotor, the temperature drops to about 120°C and the humidity is slightly high. The regenerated air RA that still has desorption capacity is transferred to the second desorption zone 6.
to desorb the adsorbed moisture.

Above we have traced how the treated air and regeneration air interact with each part of the rotor as they pass through each part.
The following will explain how a portion of the rotor interacts with the process air and the regeneration air during one rotation in the direction of the arrow in the figure.

The rotor part, which has been desorbed from adsorbed moisture in the desorption zone 6.5 and cooled by low-humidity precooled air at room temperature or slightly higher than room temperature in the precooling zone 4, is first cooled in the second stage adsorption zone 3 after the first stage adsorption step. (Example: 30℃) The treated air is further dehumidified mainly using synthetic zeolite to produce ultra-low dew point air, and then in the first stage adsorption zone 2, the treated air, for example, outside air at 20℃, is supplied. Dehumidifies with metal silicate erogel. The rotor portion, which has thus adsorbed moisture and has become slightly heated, desorbs and regenerates the metal silicate aerogel in the second stage desorption zone 6 with regeneration air at approximately 120"C, and then regenerates at approximately 180"C in the first desorption zone 5. The synthetic zeolite is mainly desorbed and regenerated by air, and then cooled to room temperature or near room temperature through precooled air, preferably a part of the dehumidified supply air SA, in precooling zone 4, and the above steps are repeated.

In the above embodiments of the present invention, magnesium silicate Erogel was used as a gas adsorbent with normal gas adsorption performance, and synthetic zeolite was used as a gas adsorption agent with extremely high gas adsorption performance for gases with low gas concentration. We have explained an example of obtaining air with an ultra-low dew point by adsorbing moisture in the air by combining silica aerogel and synthetic zeolite, using silica aerogel instead of the above-mentioned magnesium silicate aerogel as a gas adsorbent with normal gas adsorption performance. It is also possible to use a combination with In addition to the above, gas adsorbents include silica gel, alumina gel, activated carbon, etc., and active components in the gas to be adsorbed and removed include carbon monoxide, sulfur oxides, ammonia, hydrogen sulfide, organic solvent vapor, etc. Depending on the type of gas in the gas to be adsorbed and removed, it is possible to use only one type of gas adsorbent or a combination of three or more types of gas adsorbents, or to divide the adsorption zone into three or more stages and perform a multi-stage process. Adsorption operations can also be performed. On the other hand, the desorption zone may be only one part, but energy can be saved if the desorption zone is divided into two or more parts and desorption is performed in multiple stages by increasing the desorption temperature sequentially, as will be described later. Further, in place of the above-mentioned gas adsorbent, a rotor impregnated with a gas absorbent such as a lithium chloride aqueous solution for moisture absorption and dried may be used in the same manner.

An example of the case where air is dehumidified according to the above embodiment is shown on the next page as shown in the diagram.

At the time of startup, the temperature of the desorption air entering the second desorption/desorption zone 6 may not be sufficient, so a heater 1 is installed in this area.
3 is desirable, and the humidity of the regenerated air can be controlled by raising or lowering the temperature of the heater 9.13.

Effects of the Invention Since the present invention has the above-described configuration, it is not necessary to arrange two rotors for adsorption in parallel and perform a two-step adsorption operation as in the conventional method, and the drive device, casing, seal, and piping can be performed using one rotor. By simply attaching the gas, you can obtain a gas in which the active gas in the processing gas has been removed to an ultra-low concentration. For example, when comparing the same moisture adsorbent with the same rotor pore diameter and thickness, two rotors with a diameter of 5DOIIIm are required to obtain ultra-low dew point air with a dew point of -80'C or less using the conventional method. 1) Be-1-1 田QQ QQQ の 口 um 0 口 、
)+! 8 8 8 〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉
Baba Attack 1
This can be done with one rotor of 0+nn+ diameter, the structure is simple and therefore the cost is low, and the power cost can be greatly saved, the installation area is small, and the maintenance cost is also reduced.

Also, to explain using the above example of dehumidification, in a dehumidifying operation, if the temperature of the rotor is high, its moisture absorption ability decreases, so the rotor part after desorption and regeneration is heated in the precooling zone 4 with precooled air at almost room temperature, preferably with extremely low humidity. After precooling a portion of the air SA, dehumidification is performed. Here, a portion of outside air, preferably low temperature and low humidity outside air, may be introduced as the precooling air.

In the dehumidification operation, first, the low-humidity air, that is, the air that has undergone considerable dehumidification processing in the first-stage dehumidification zone 2, is dehumidified to an ultra-low dew point in the second-stage dehumidification zone 3, and then the small amount of moisture adsorbed at that point is dehumidified. The rotor section containing can adsorb a sufficient amount of moisture from the process air in the first stage dehumidification zone 2.

Next, in the desorption operation, if the dehumidified air that is first used for pre-cooling and then heated as a result is heated by the regeneration air heating heater 9 and used as regeneration air, compared to the case where only outside air is heated and used as regeneration air. Since its relative humidity is low, the desorption effect is large. Desorption, or regeneration, may be performed in one stage, but
If this is made into two stages and the second stage desorption zone 6 and the first stage desorption zone 5 are provided as in the above embodiment and desorption and regeneration is performed in the two stages, a considerable amount of water that is discharged from the first stage desorption zone 5 can be removed. The hot regenerated waste gas can be further used for desorption regeneration in the second stage desorption zone 6, resulting in thermal energy savings. In addition, when two types of sorbents are used together as in the above example, the first stage has a temperature and dryness that are a little low and a little high, but are sufficient for normal level regeneration. The relatively low temperature due to the regenerated waste gas in the desorption zone 5, e.g. 8
A sorbent, such as silica alumina aerogel, which can be desorbed and regenerated at temperatures between 0 and 110°C, is regenerated in the second stage desorption zone and then regenerated in the first stage desorption using the exhaust gas from the pre-cooling zone 4, which has a high temperature and low relative humidity. In the desorption zone 5 it is possible to regenerate sorbents that require high temperatures for desorption regeneration, such as synthetic zeolites. When one type of sorbent is used or when two or more types of sorbents having substantially the same regeneration temperature are used in combination, only one part of the regeneration zone may be used.

Although FIG. 1 shows that the process air is passed through the rotor from bottom to top and the regeneration air is passed from top to bottom in opposite directions within the rotor, this can be selected as appropriate depending on the piping space. However, from the point of view of waste heat utilization, the dehumidification efficiency will be improved if the treated air and regenerated air flow in opposite directions.

In addition, in FIG. 1, the lower part of the rotor l is mainly composed of magnesium silicate aerogel, an adsorbent that has normal gas adsorption performance and has a relatively low desorption and regeneration temperature, and the upper part is made of magnesium silicate aerogel and synthetic zeolite, that is, an adsorbent that has a relatively low desorption and regeneration temperature. If it is configured in combination with an adsorbent that has extremely high gas adsorption performance for gases with low gas concentrations and a relatively high desorption and regeneration temperature, magnesium silicate Erogel will be produced in the lower part when treated air is introduced from below in the adsorption process. After a considerable amount of gas is adsorbed and removed, residual gas is further adsorbed mainly by synthetic zeolite in the upper part, so gas in the -layer air can be adsorbed and removed to an ultra-low concentration. When regeneration air is introduced from above, the temperature of the regeneration air gradually decreases as it passes through the small holes in the rotor, but in the upper part, the high temperature regeneration air regenerates synthetic zeolite whose desorption and regeneration temperature is relatively high. After that, the magnesium silicate aerogel, which has a relatively low desorption and regeneration temperature, can be regenerated by the regeneration air whose temperature has been slightly lowered in the lower part, and the regeneration thermal energy can be used effectively.

In general, when adsorbing gases using a solid adsorbent, including the case of moisture absorption mentioned above, the lower the temperature, the more the adsorption reaction progresses, and the higher the temperature, the more difficult the adsorption becomes, and the more the desorption reaction tends to progress. The same effect can be achieved by selecting an adsorbent or a combination thereof suitable for each adsorbed gas.

[Brief explanation of the drawing]

Claims (1)

[Claims] 1. A gas sorption rotor having a large number of small through holes extending from one end surface to the other end surface of a cylinder and in which a gas sorbent appears on the surface of each small hole is rotated. An ultra-low concentration gas sorption machine configured such that each of its parts sequentially functions as two or more sorption zones, one part precooling zone, and one or more desorption zones. 2. Claim 1 in which the gas sorbent is a gas adsorbent
Ultra-low concentration gas sorption machine described in Section 1. 3. Ultra-low concentration gas according to claim 2, in which a gas adsorbent having normal gas adsorption performance and a gas adsorbent having extremely high gas adsorption performance for gases with low gas concentration are used in combination. Sorption machine. 4. Claim 3, wherein the gas adsorbent having normal gas adsorption performance is silica aerogel or metal silicate aerogel, and the gas adsorbent having extremely high gas adsorption performance for gases with low gas concentration is synthetic zeolite. Ultra-low concentration gas sorption machine described. 5. Claim 1 in which the gas sorbent is a gas absorbent
Ultra-low concentration gas sorption machine described in Section 1. 6. The ultra-low concentration gas sorption machine according to claims 1 to 5, wherein the gas is water vapor and the gas sorption machine is a dehumidifier.