JPH0620508B2 - Dehumidification method of pressurized air - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for efficiently dehumidifying pressurized air.

[Conventional technology]

As a method for removing water in pressurized air, an adsorption-type dehumidifying method is widely used today.

In this method, one of two adsorption towers packed with an adsorbent such as silica gel, alumina gel, or zeolite is passed through an adsorption step in which moist compressed air is passed, dehumidified and dried, and taken out of the system, and the other adsorption is performed. In the tower, after heating the adsorbent to desorb the water adsorbed by the adsorbent, a heating regeneration step of regenerating the adsorbent through steps such as cooling is performed, and the steps of both towers are alternated. It is a method of continuously removing the water content of the pressurized air by switching to.

In general, water in pressurized air consists of water droplets and water vapor that are saturated and condensed due to cooling after the atmospheric humidity is cooled, and the water droplets that are produced can be removed with a filter, but water vapor cannot be removed with it. It is widely practiced to remove them by adsorbing them on an adsorbent. Therefore, the method as described above is adopted.

Thus, although water vapor is removed in the adsorption step described above, when the adsorbent becomes saturated, it is necessary to desorb moisture from the adsorbent by heating air. Is heated with a heater and introduced into the adsorption tower with a blower or the like to perform heat regeneration for 2 to 3 hours, but the heating is stopped when the temperature at the tower outlet rises. That is, the heating time can be set by the air volume and the heater capacity. On the other hand, cooling is generally performed by using a part of the dried product air and passing through the inside of the tower, and if the temperature inside the tower is close to room temperature,
The regeneration process is completed.

[Problems to be solved by the invention]

However, the cooling time in the above method depends only on the dry air to be passed, and if the cooling time is to be shortened, a large amount of the product dry air must be consumed, so that the amount is naturally limited. Conventionally, this cooling process requires 2 to 3 hours, and when the adsorption tower switching time becomes long, the amount of dry air consumed at the same time is inevitably increased, and further, the switching time is long. However, there is a problem in that the size of the device becomes large, the cost increases, and it becomes uneconomical.

[Means for solving problems]

The present invention solves the problems of the prior art as described above, and greatly reduces the 2-3 hours conventionally required for cooling the adsorption tower,
The purpose of the present invention is to provide a dehumidification method that makes it possible to reduce the switching time of the tower to about half that of the conventional method. The composition is silica gel, alumina gel,
Two adsorption towers filled with an adsorbent such as zeolite are arranged in parallel, and one of the adsorption towers is allowed to pass through moist air to adsorb and remove moisture, and at the same time monitor the moisture content of the adsorbent by a humidity detector, When water breakthrough occurs in the adsorbent, in the adsorption type dehumidification method of switching to the other tower and continuing dehumidification and regenerating the adsorption tower that was previously in the adsorption step, when regenerating the adsorption tower, After heating inside air at atmospheric pressure through external air, the total amount of pressurized dry air at the outlet of another adsorption tower in the adsorption step is cooled under pressure and the dried air heated by the cooling is cooled by a cooler. The feature is that the dry air returned to room temperature is recovered without substantially impairing its pressure and capacity.

That is, the main point of the method of the present invention is that the entire amount of the product dry air is used for cooling the adsorption tower after the heating and regeneration. By doing this, the tower heated to a high temperature by heating and regeneration is pressurized to the adsorption pressure by the pressurized air, and then by switching the product dry air extraction line,
The whole amount is introduced into the high temperature tower, the tower is cooled and the high temperature air discharged is cooled by a means such as a cooler, the temperature is lowered and it is returned to the dry air supply line and taken out as product air. To Since the high temperature tower can obtain a large amount of cooling air as compared with the passage of cooling air in the conventional method, the cooling time is shortened to 1/10 or less of that in the conventional method. Furthermore, in order to save energy, the high temperature energy discharged from the tower can be used for assisting a heater for regenerative heating if it is recovered in a heat storage layer without being cooled by a cooler or the like.

On the other hand, the cooling time required by the conventional method was 2 to 3 hours.
Since it will be improved in about 10 to 15 minutes, the adsorption time of the column can be shortened to 3 to 4 hours. Therefore, it is possible to obtain a sufficient result with an apparatus that is about half the size of an apparatus that has conventionally set an adsorption time of 8 hours.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

The figure is a flow sheet of an apparatus for carrying out the method of the present invention.
B is an adsorption tower filled with an adsorbent such as silica gel, alumina gel, or zeolite, 1 is a blower, 2 is a heater, 3 is a cooler, 4 is a humidity detection sensor, 5 is a temperature detection sensor, and 6 is a pressure saturated with water. A valve provided in the air supply line C, 7,
7 ', 8,8', 9,9'10,10 ', 11,11', 12,1
2'and 13 are automatic valves, 14 is a valve provided in the product air line D, E is a discharge line, and F is a cooling line.

Now, it is assumed that the adsorption tower A is performing the adsorption step, and the adsorption tower B is also performing the heating step for regeneration.

In this state, valve 6, automatic valve 7, 12, valve 14, automatic valve
8'and 11 'are open and the other valves and / or the automatic valve are closed.

In the adsorption process, the compressed air from the compressor, which is saturated with water and should be dehumidified, is discharged from the line C through the valve 6 and the automatic valve 7.
After being introduced into the adsorption tower A, passed through the adsorption tower A, dehumidified and dried, then passed through the automatic valve 12, cooled by the cooler 3, and taken out of the system as product air from the valve 14 of the line D. Be done.

On the other hand, in the heating step, the air from the blower 1 is heated to 180 ° C. by the heater 2 in the vicinity of the atmospheric pressure and introduced from the top of the adsorption tower B via the automatic valve 11 ′ to regenerate the adsorbent by heating and desorb it. The steam and the steam are discharged from the discharge line E through the automatic valve 8'to the outside of the system. In this heating and regeneration process, when the temperature sensor 5 installed in the line E detects the set temperature (90 to 120 ° C). finish.

When the heating process is completed in this way, the automatic valve 8'is closed and the automatic valve 13 is opened, and the pressurized air discharged from the top of the adsorption tower A is introduced into the adsorption tower B, whereby the tower B Is increased to match the pressure of the supplied pressurized air, and the cooling process starts. In this cooling step, the automatic valves 9'and 10 are opened to connect the bottom of the tower B to the top of the tower A, and further the automatic valve 1 at the top of the tower.
If 2'is opened and the automatic valves 12 and 13 are closed at the same time, the entire amount of dry air flows through the cooling line F from the bottom to the top of the tower B, and the tower B is cooled. The high temperature dry air discharged from the top of the tower B by this cooling step is cooled to room temperature by the cooler 3 and taken out of the system as product air from the valve 14 of the line D.

Further, the adsorption step ends when the relative humidity exceeds the set value by the humidity detection sensor 4 installed in the cooling line F. However, even if the set value of the relative humidity is increased, in the detection thereof, The presence of the adsorption tower B significantly improves the dryness at the outlet, resulting in air (DP-40 ° C) having an extremely low dew point.

On the other hand, when the outlet relative humidity of the adsorption tower A reaches 20 to 50%,
By switching the adsorption step to the adsorption tower B and repeating the same operation thereafter, dehumidification of the pressurized air is continuously performed.

〔The invention's effect〕

The present invention is as described above, and according to the method of the present invention, not only is it possible to recover almost all the dry air for cooling that has been conventionally discarded, but the cooling time can be shortened to 1/10 or less of the conventional method, Therefore, the size of the adsorption tower can be set to 1/2 of that of the conventional method, which is extremely economical. Moreover, when switching the adsorption tower, the humidity sensor is used to follow the seasonal changes of the four seasons and the total load. It is possible to operate, and it is possible to perform dehumidifying operation that is extremely energy-saving.

In particular, in the conventional method, the switching of the adsorption tower was mostly the method of switching at the time when the breakthrough point was detected, but according to the present invention, even if the breakthrough point is passed and the outlet relative humidity exceeds 50%. Since the dew point of -40 ° C can be obtained sufficiently and the adsorbent in the tower can be set to the saturated adsorption amount, the switching time becomes long and the energy saving effect becomes extremely large.

[Brief description of drawings]

The figure is a flow sheet of an embodiment of the present invention. A, B ... Adsorption tower, C ... Pressurized air supply line, D ...
Product air extraction line, E ... exhaust line, F ... cooling line, 1 ... blower, 2 ... heater, 3 ... cooler,
4 ... Humidity detection sensor, 5 ... Temperature detection sensor, 6, 14
... Valves, 7,7 ', 8,8', 9,9 ', 10,10', 11,1
1 ', 12, 12', 13, 13 '... Automatic valve

Claims (1)

[Claims] 1. A pair of adsorption towers filled with an adsorbent such as silica gel, alumina gel, zeolite, etc. are arranged in parallel, and one of the adsorption towers is allowed to pass moist air to adsorb and remove moisture to be dried, and a humidity detector. To monitor the water content of the adsorbent,
When water breakthrough occurs in the adsorbent, in the adsorption type dehumidification method of switching to the other tower and continuing dehumidification and regenerating the adsorption tower that was previously in the adsorption step, when regenerating the adsorption tower, After heating inside air at atmospheric pressure through external air, the total amount of pressurized dry air at the outlet of another adsorption tower in the adsorption step is cooled under pressure and the dried air heated by the cooling is cooled by a cooler. A method for dehumidifying compressed air, which comprises recovering dry air returned to room temperature without substantially impairing its pressure and capacity.