JP2687070B2 - How to prepare dry air - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing dry air widely used in various fields, and more particularly to a method for preparing dry air having a high dehumidifying effect.

[0002]

2. Description of the Related Art Dry air is used for manufacturing, assembling and storing electronic parts, electronic devices, etc., for manufacturing and storing dry food, and for drying and storing various other products. The same applies to the following: (equal to the equipment for setting and adjusting the set value for automatic control or adjusting the control operation, the same applies to the following). Widely used in driving and various other fields.

[0003] Such dry air uses air in the atmosphere, air after being used in the above fields or other fields as a raw material, and uses this as a liquid hygroscopic agent such as concentrated sulfuric acid,
It is generally prepared by absorbing or removing water through a solid hygroscopic agent such as calcium carbonate, activated carbon, zeolite or silica gel.

By the way, in the technology of reforming and decomposing petroleum, manufacturing and refining of other various petroleum products, a method of using a specific catalyst has been generally practiced.
The catalyst in such a field is usually packed in an apparatus called a contact tower, and used, for example, as follows.

A plurality of, for example, two contact towers described above are installed, and one of the towers is used for the above-mentioned reforming, decomposition, production and purification (hereinafter collectively referred to as "contact"). , The catalyst is regenerated in the other tower, and after a certain time has passed, the contact tower whose regeneration has been completed and the contact tower whose activity has deteriorated are automatically switched, and contact and regeneration are continuously performed without interruption. To do.

Alternatively, a contact tower and a catalyst regeneration unit are installed close to each other, a part of the catalyst is extracted from the contact column and sent to a catalyst regeneration unit, and a part of the catalyst regenerated here is transferred to the contact column. Circulate (hereinafter, this catalyst circulation system will be referred to as "CC
R method ").

In such a usage mode of the catalyst, a step of drying the catalyst by aeration of dry air is performed immediately before the end of the regeneration step. This dry air is, for example, air used for the equipment for controlling the above-mentioned plant for reforming or cracking petroleum, or for controlling the above-mentioned two contact towers (hereinafter, abbreviated as “instrumentation”) (hereinafter, “instrument”). , "Instrumentation air"), that is, the air is used as it is, or after being compressed, it is dried by aeration with the above-mentioned various hygroscopic agents.

[0008]

By the way, in the dry air used in the above-mentioned catalyst drying step, particularly in the CCR system catalyst drying step, excess water (reaction inhibiting factor) generated during catalyst regeneration is used in the reaction system. Since it is used to suppress the inflow into the air, the moisture content allowed in this dry air is a very strict value (about 5 ppm at 3.2 atm, dew point about -60 ° C in atmospheric pressure conversion). ).

However, the dry air prepared as described above cannot satisfy such a water content allowable value, and it is often difficult to guarantee the dry quality of the regenerated catalyst.

If the drying quality is not good (that is, if the drying is not carried out sufficiently), the chemicals and detergents used for the regeneration of the catalyst may remain, which may adversely affect the catalyst and cause the catalyst activity. It is not possible or impossible to regenerate the catalyst, or the life of the catalyst is shortened. As a result, the contact step is adversely affected and the quality of the contact product is deteriorated.

In order to prevent such a situation, a liquid or solid hygroscopic agent having high hygroscopicity is used, or a large amount of these hygroscopic agents having high hygroscopicity are used, and further, these hygroscopic agents are used. It is inevitable to take measures such as installing a plurality of high-performance dehumidifiers that use a large amount of hygroscopic agent having a hygroscopic property and allowing raw material air to pass through these devices in series.

However, each of these measures has a drawback that not only the cost of the hygroscopic agent but also the cost of the apparatus and the operating cost are high.

The present invention eliminates the above-mentioned situation, and in particular, prepares dry air which can always guarantee the allowable moisture content required for the dry air used for catalyst regeneration in the CCR system at low cost. The purpose is to propose a possible method.

[0014]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventors have found that (1) the CC
From the viewpoint of energy saving, the preparation of dry air used for R-type catalyst regeneration is performed by using a solid moisture absorbent (hereinafter referred to as “adsorbent”).
The heatless dehumidifier according to (1) is used frequently, and the heatless dehumidifier regenerates the adsorbent by the heat of adsorption when adsorbing water in the raw material air, but this is functioning sufficiently. (2) In pursuit of this cause, the raw air to be ventilated in the heatless dehumidifier was prepared as the instrumentation air described above in order to further improve the dryness of the product drying air (for example, already Since the heatless dehumidifier is ventilated), the water content is considerably reduced, and it is impossible to generate a sufficient amount of heat to regenerate the adsorbent of the dehumidifier. (3) Even if this raw material air is replaced with air with a large amount of water or air for plants, C
It was impossible to prepare dry air with a high degree of dryness required for CR system catalyst regeneration air,
(4) Therefore, we changed the idea and used it as raw material air,
When the instrument air, which has already passed through the heatless dehumidifier and has a reduced water content, is rehumidified and adjusted to a water content capable of generating the above-mentioned heat of adsorption, a heatless dehumidifier is used. It has been found that the adsorbent in the vessel can be regenerated favorably, and the dryness of the product drying air can be always guaranteed to the allowable water content required for the CCR type catalyst regeneration air.

The present invention has been made on the basis of the above findings (1) to (4), in which instrument air is used as the raw material air, the instrument air is once humidified, and then the heatless dehumidifier is used. The gist is a method for preparing dry air, which is characterized in that The dry air prepared by the method of the present invention is not limited to the above-mentioned CCR-type catalyst regeneration, but may be suitably used in various other fields described above, particularly in fields requiring high-dryness dry air. You can

In the present invention, the instrumentation air used as the raw material air may be the one prepared as the above-mentioned instrumentation air, for example, the one which has been passed through a heatless dehumidifier after compressing the atmosphere. it can.

The above-mentioned raw material air is humidified by, for example, passing the raw material air through water while bubbling it, passing it through a water sprinkling tower, or passing it through a container kept at a constant humidity.

The water used at this time or the steam for maintaining the above-mentioned humidity depends not only on pure water but also on the use of dry air. In addition to tap water and industrial water, condensate of boilers and various devices driven by steam, etc.
And steam with these waters can be preferably used.

The degree of humidification of the raw material air by water or steam as described above depends on the type and function of the heatless dehumidifier used, in other words, the type and performance of the hygroscopic agent used in the dehumidifier. Differently, it cannot be determined in a general way, but if it is too small, the humidifying effect does not appear, and conversely, if it is too large, the desired dehumidifying effect cannot be obtained. , 30 ° C, 3.2 atm
At about 5 ppm to saturation, preferably about 10 pp
It is preferable that m to be saturated. From this range, the optimum degree of humidification may be appropriately selected according to the type and function of the heatless dehumidifier (that is, the type and performance of the adsorbent). As the heatless dehumidifier, an ordinary heatless dehumidifier filled with an adsorbent can be used as it is.

[0020]

In the method of the present invention, since the raw material air supplied to the heatless dehumidifier is adjusted to have an appropriate amount of moisture, when the moisture is adsorbed by the dehumidifier, an appropriate amount of heat of adsorption is generated. Occur. This heat of adsorption favorably regenerates the adsorbent whose performance has deteriorated due to the adsorption of water. Therefore, the dehumidifying effect of the heatless dehumidifier is kept good, and as a result,
The dryness of the dry air prepared by the method of the present invention is always guaranteed to the desired value.

Further, in the method of the present invention, in the step of humidifying the raw material air, scraps of metals and metal oxides in the air (various scales coming out from various equipments and pipes in the distribution line of the raw material air), etc. When various dusts and the like are contained, these contained substances are removed, and clean dry air can be obtained.

Further, in the method of the present invention, a normal simple humidifier is newly added to the minimum equipment required for the prior art (raw air supply means and heatless dehumidifier) as means for humidifying the raw air. All you have to do is add. Therefore, in the method of the present invention, for example, both the apparatus cost and the operating cost for obtaining high-quality dry air having a high degree of dryness, which is suitable as CCR-type catalyst regeneration air and the like,
It can be kept very inexpensive.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram schematically showing a structural example of an apparatus suitable for carrying out the method of the present invention. In FIG.
Raw material air (instrumentation air) is introduced into the humidifier 2 from the line 1. As the humidifier 2, a line 3 is used in this example.
Although a method of bubbling raw material air into a container filled with pure water 21 introduced from the above is shown, the method of the present invention is not limited to this, and as described above, water is sprinkled from the upper part and sprinkled from the lower part. Various methods such as a method of flowing the raw material air toward the upper side or a method of flowing the raw material air into a container kept at high humidity can be used. Further, not only pure water but also normal tap water, industrial water, or steam condensate can be used depending on the use of dry air as described above.

In the humidifier 2 of the present embodiment, the residence time of the raw material air in the humidifier 2 is adjusted to adjust the degree of humidification of the raw material air (for example, a vertical container is used. , The amount of the pure water 21 to be filled is adjusted, or the bubbling portion is installed at the bottom or the upper portion of the pure water 21.
It is possible to realize it by adjusting the time for passing through 1).

The raw material air that has been humidified to a constant water content by the humidifier 2 is introduced into the heatless dehumidifier 5 through the line 4. As the heatless dehumidifier 5, in this example, two synthetic zeolites manufactured by Bayer (Germany) as the adsorbent and filled with the trade name “Bayrit KE-254” were installed (not shown), and one of them was air-dried. The other is used for regenerating an adsorbent having a reduced water adsorption capacity, and after switching for a certain period of time, these are switched to continuously supply dry air. Of course, the present invention is not limited to this method, and may be one having only one unit or three or more units,
It may be filled with another heatless type adsorbent.

In addition, when it is not necessary to humidify the material air (that is, when the moisture content is approximately 5 ppm to the saturated water content at 3.2 atm described above) or the adsorbent in the heatless dehumidifier 5 is sufficient. Since there is a case where the humidification of the raw material air is not necessary when it has an adsorption capacity, a line 6 that bypasses the humidifier 2 is provided in the example of FIG. 1, and in such a case, The line 6 can be directly introduced into the heatless dehumidifier 5.

The product drying air taken out from the heatless dehumidifier 5 is supplied from a line 7 to a predetermined device (not shown).
Sent to and used for a predetermined purpose. A specific example (an example simulating preparation of dry air to be sent to a device for regenerating a catalyst for reforming petroleum according to the CCR method described above) performed by using the device shown in FIG. 1 is shown below. The method will be described more specifically.

Concrete Example The raw material air has a water content of 3.2 atm and is about 20 ppm.
Use instrumentation air with a dew point of approximately -41 ° C to -42 ° C in terms of atmospheric pressure (that is, air that has been compressed by passing it through a heatless dehumidifier (not shown) to remove water). did. The humidifier 2 uses pure water 2 so that the moisture content of the raw material air after humidification becomes various amounts as shown in Table 1.
The amount of 1 was appropriately adjusted and used.

The heatless type dehumidifier 5 has a function of obtaining dry air having a water content of 5 ppm at 3.2 atm (a dew point is about -60 ° C. in terms of atmospheric pressure) (the above-mentioned adsorbent filling amount is 1 Two units (each having a capacity of 125 kg per 0.219 m ³ ) are used, and these two heatless dehumidifiers 5 alternately perform air drying and regeneration every 5 minutes.

As the regenerating air at this time, a part of the product air obtained in this example was pooled separately and used. The conditions for regeneration air are 2.2 kg / cm ²
It was decided to supply the material pressurized at 115 Nm ³ / hr. The results obtained under the above conditions are shown in Table 1.

[0031]

[Table 1]

[0032]

As described above in detail, according to the method of the present invention, dry air that can be suitably used in a field requiring a high degree of dryness such as CCR system catalyst regeneration is used. It can be prepared simply by performing an operation of humidifying the raw material air. Further, according to the method of the present invention, clean dry air containing extremely few impurities can be prepared. Further, the apparatus cost applied to the method of the present invention is low, the operating cost is also low, and dry air of high dryness and high quality can be prepared easily and economically.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of the configuration of an apparatus used when carrying out the method of the present invention.

[Explanation of symbols]

 1 Raw air introduction line 2 Humidifier 3 Humidification water introduction line 4 Air flow path after humidification 5 Heatless dehumidifier 6 Humidifier 2 bypass line 7 Product dry air extraction line 21 Water in humidifier 2

Claims (1)

(57) [Claims] 1. A method for preparing dry air, which comprises using instrumentation air as raw material air, humidifying the instrumentation air once, and then passing the instrumentation air through a heatless dehumidifier.