JP2000350917A - Method and device for dehumidifying compressed air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce running costs by a method wherein, in an energy saving operation, adsorbents in one of two adsorption cylinders and those in the other one are caused to be concurrently deteriorated to suppress variation in dew point when a normal operation is restored, whereby replacement operation of adsorbents of both the cylinders can be simultaneously carried out. SOLUTION: In the method for dehumidifying compressed air, a drying process wherein humid compressed gas is fed into one of adsorption cylinders 3, 4 each filled with adsorbents to effect adsorption and dehumidification and a regeneration process wherein a part of dry gas obtained in the drying process is led to the other adsorption cylinder wherein the moisture-adsorptivity of the adsorbents is lowered in the drying process in the preceding step to desorb moisture from the adsorbents, thereby purging the desorbed moisture from the cylinder, are parallelly performed. The drying process and regenerating process are carried out by alternately switching both the cylinders to each other to continuously supply dry gas. In that method, an energy saving operation is performed under predetermined conditions to suspend the regeneration process, and a regeneration process is carried out at predetermined cycles during the energy saving operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for dehumidifying a compressed gas, in which a wet compressed gas is adsorbed and dehumidified using an adsorbent and dried, and in particular, to prevent early deterioration of the adsorbent. Related to energy saving driving.

[0002]

2. Description of the Related Art In a conventional dehumidifier, two adsorption cylinders are prepared in which a container is filled with an adsorbent such as activated alumina, silica gel, synthetic zeolite or lithium chloride in order to continuously supply dry air. .

[0003] Wet compressed air is guided to one of the adsorption columns to perform adsorption drying, and is supplied to a predetermined supply destination. At the same time, a part of the obtained dry air is guided to the other adsorption column, and moisture is desorbed from the adsorbent having reduced moisture absorption capacity in the previous stage, and the moisture is further purged from the adsorption column. Eggplant In this regeneration step, about 20 percent of the resulting dry air was released to the atmosphere.

The drying of the compressed air in one of the adsorption cylinders and the regeneration of the adsorbent in the other adsorption cylinder are performed simultaneously in parallel, and a switching valve provided between the adsorption cylinders after a predetermined time has elapsed. Switch to continuously supply dry air.

[0005] Since the dehumidifier is designed on the basis of the harshest summer conditions in which the ambient temperature and the inlet air temperature rise, for example, when the dehumidifier is used in winter or when the load on the supply destination is reduced, the adsorption is performed. It is desirable to reduce the adsorbing action of the agent to extend the life.

Conventionally, energy saving operation as shown in FIG. 9 has been performed. That is, the switching operation of the switching valve is stopped, and all of the purge valves connected to the respective adsorption columns are closed. For example, while the wet compressed air is guided only to the cylinder B to continue the drying for adsorption and dehumidification, the regeneration of both the cylinders A and B is interrupted.

[0007]

When the switching operation of the switching valve is stopped and all the purge valves connected to the adsorption cylinder are closed during the energy saving operation, the amount of dry air discharged by the purge is reduced. Decreases. However, depending on conditions, the above-described energy saving operation may be continued for a long time. During this time, the adsorbing action is performed only by the adsorbent in one of the adsorption cylinders, and the adsorbent in the other adsorption cylinder has no effect.

[0008] Therefore, in the state where the operation is returned to the standard operation, the balance between the amount of water adsorbed by the adsorbent in the adsorber which has been continuously dehumidified and dried and the amount of water adsorbed by the adsorbent in the other adsorber having no function is poor. Become. Actually, the dew point temperature of the dry air supplied from the side where the dehumidification and drying is continued becomes higher than the dew point temperature of the dry air supplied from the other side.

Eventually, the adsorbent on the side that has continued the adsorption operation for a long time deteriorates earlier than the adsorbent on the other side, and it becomes necessary to replace it with a new adsorbent. If either one of the adsorbents deteriorates, both of them are generally replaced, and for the other, the replacement is useless and adversely affects the running cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to reduce the amount of dry air discharged by purging during a so-called energy-saving operation and to reduce the amount of dry air. The deterioration of the adsorbent in the inside progresses evenly, the fluctuation of the dew point temperature between each adsorption cylinder when returning to the standard operation is suppressed, and the timing of the adsorbent exchange is eliminated at the same time to eliminate unnecessary exchange and run. An object of the present invention is to provide a method and an apparatus for dehumidifying compressed gas which contribute to cost reduction.

[0011]

In order to satisfy the above-mentioned object, a method for dehumidifying a compressed gas according to the present invention is characterized in that a wet compressed gas is supplied to one of two adsorption cylinders filled with an adsorbent. A drying step of conducting the adsorption and dehumidification, and a part of the dry gas obtained in the drying step is led to the other adsorption column having a reduced hygroscopic capacity in the drying step in the previous stage to desorb and desorb moisture from the adsorbent. The regeneration step of purging the collected moisture from the adsorption column is performed in parallel, and the drying step and the regeneration step are alternately switched between the adsorption columns to continuously supply a dry gas under a predetermined condition. The method is characterized in that the regeneration step is stopped, and the regeneration step is performed in a predetermined cycle during the stop.

According to a second aspect of the present invention, in the method for dehumidifying a compressed gas according to the first aspect, the drying step is alternately continued between the two adsorption columns while the regeneration step is stopped under the predetermined condition. Characterized in that only the adsorption cylinder is continued.

In order to satisfy the above object, a compressed gas dehumidifier according to the present invention is characterized in that, as claim 3, two adsorption cylinders filled with an adsorbent, a communication path for communicating these adsorption cylinders via switching means, and An adsorbent having a purging means, wherein the wet compressed gas is guided to one of the adsorption columns to be adsorbed and dehumidified and dried, and a part of the dried gas is directed to the other adsorption column to reduce the hygroscopic capacity in the previous stage. The regeneration in which moisture is desorbed from the purging means and the desorbed moisture is purged from the adsorption cylinder by the purging means is performed in parallel, and drying and regeneration are alternately switched between the two adsorption cylinders based on the switching of the switching means. A dehumidifying device for supplying a dry gas in an energy-saving manner in which the regeneration step is stopped under a predetermined condition, and a control means for controlling the regeneration step in a predetermined cycle during the energy-saving operation. To And butterflies.

By adopting a means for solving such a problem, a so-called energy-saving operation for stopping the regeneration step under a predetermined condition is performed, and also in this case, the forced purging of both in-cylinder adsorbents is performed in a predetermined cycle. By doing so, the deterioration of the adsorbent proceeds evenly while suppressing the purge amount to a small amount, the fluctuation of the dew point temperature between the adsorption cylinders when returning to the standard operation can be suppressed, and the timing of adsorbent replacement Can be taken at the same time.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the appearance of a compressed gas dehumidifier. This dehumidifier includes a lower frame 1, an electric component box 2 mounted on one side of the frame 1, and two adsorption cylinders mounted on the other side of the frame 1 (for convenience of explanation, Hereinafter, the left suction cylinder in the figure is referred to as an A cylinder,
The right suction cylinder in the figure is called a B cylinder) 3, 4 and these A, B
It comprises an outlet head 5 mounted over the upper ends of the cylinders 3 and 4 and an inlet head (not shown) mounted over the lower ends of the A and B cylinders.

The outlet head 5 is attached and fixed to the gantry 1 via a plurality of column bolts 6 and nuts 7 so that the A and B cylinders 3 and 4 are fixed and held. The inlet head is shielded by a lid plate 8 attached to the gantry 1.

On one side of the outlet head 5,
A supply port 9 for supplying and guiding the gas adsorbed and dried in the apparatus to a predetermined destination is provided, and an inlet 1 for introducing and guiding the wet compressed gas into the apparatus is provided on one side of the gantry 1.
0 is opened.

A humidity indicator 11 is provided at the center of the outlet head 5 and accommodates a member which comes into contact with the adsorbed and dried gas and changes color when the gas exceeds a predetermined relative humidity. . That is, the humidity indicator 11 detects the degree of deterioration of the adsorbent contained in the A and B cylinders 3 and 4.

Further, the outlet head 5 has A, B
Purge orifice 1 communicating with upper ends of both cylinders 3 and 4
2 are provided. On the side opposite to the purge orifice 12, a pair of connection ports 13 for connecting a purge valve described later is provided.

FIG. 2 and FIG. 3 schematically show cross sections of the same suction device, in which the functions are different from each other. The A and B cylinders 3 and 4 are each formed of a cylinder whose upper and lower end surfaces are open. The upper end opening is inserted into a concave portion 5a provided on the lower surface of the outlet head 5, and the lower end opening is as described above. It is inserted into a concave portion 15 a provided on the upper surface of the inlet head 15.

The porous plate 16 is located at a predetermined distance from the upper end opening and the lower end opening of each of the A and B cylinders 3 and 4.
And the adsorbent 17 is filled between the perforated plates 16. As the adsorbent 17, activated alumina, silica gel, zeolite, or the like is used.

Each of the A,
Check valves 18A, 18 are located at positions facing the central portions of B cylinders 3, 4.
A valve chamber 19 containing B is formed. These check valves 18
A and 18B allow the gas to flow upward from the inside of the cylinders 3 and 4 on the lower side, and block the gas flow from the upper part into the cylinders 3 and 4.

Further, the outlet head 5 is provided with a supply passage 20 which communicates the supply outlet 9 with each valve chamber 19, and opens the check valves 18A and 18B to open the valve chamber 19.
The gas that has exited is guided to the supply port 9. In addition,
In the supply path 20, a branch path 21 communicating with the humidity indicator 11 is provided in a branched manner.

Around the respective valve chambers 19, the area where the A and B cylinders 3 and 4 are inserted is recessed, and the above-described purge orifice (in this case, drawn to be provided on the outlet head 5). The purge chamber 22 is in communication with the purge chamber 12. In other words, the purge chambers 22 and 22 are communicated with each other by the purge orifice 12.

The end of the supply path 20 opposite to the supply port 9 is closed, and a humidity sensor 23 is mounted therethrough. As shown in FIG. 2 only, a control circuit 25 as a control means is accommodated in the electric component box 2 and is electrically connected to the humidity sensor 23. The humidity sensor 23 detects the humidity of the dry air in the supply path 20 and sends a detection signal to the control circuit 25.

A switching valve 26 as switching means is attached to the lower surface of the innerlet head 15. The inlet 10 is provided on one side of the innerlet head 15, and a purge valve 27 and a silencer 28 are connected in series on the other side.

The switching valve 26 has a first port a, a second port b, a third port c,
A fourth port d and a fifth port e are sequentially provided, and the communication between the ports a to e is switched by moving the valve body f.

That is, at the position of the valve element f shown in FIG. 2, the first port a and the second port b communicate with each other.
The third port c communicates with the fourth port d. Also,
At the position of the valve element f shown in FIG. 3, the second port b communicates with the third port c, and the fourth port d communicates with the fifth port e.

The valve f is driven by a solenoid 26S. The solenoid 26S is electrically connected to the control circuit 25, and is driven and controlled as described later.

The inlet head 15 has an inlet 1
0 and the third port c of the switching valve 26, an introduction path 30 communicating the lower opening end of the A cylinder 3 with the second port b, and a lower opening of the B cylinder 4 A B-tube communication passage 32 for communicating the end with the fourth port d, and a first port a
There is provided an inverted U-shaped port communication passage 33 that communicates with the fifth port e, and a purge branch passage 34 that branches from an intermediate portion of the port communication passage 33 and communicates with the purge valve 27.

The purge valve 27 is an electromagnetic on-off valve having a normal configuration, and is electrically connected to the control circuit 25.
It opens and closes in response to a control signal from the control circuit 25, and conducts or shuts off the purge gas guided from the purge branch passage. The purge gas derived therefrom is guided to the silencer 28, silenced, and then released to the outside.

The control circuit 25 includes the humidity sensor 23
A circuit that receives the detection signal from the converter and converts it into a dew point temperature (dew point under pressure) Ta, a circuit that compares this dew point temperature Ta with a preset dew point temperature (dew point under pressure) Ts, and Based on the switching valve 26
And a circuit for controlling the opening and closing of the purge valve 27.

[0033] The suction device thus configured,
The following operation is performed. The description will be made by applying compressed air as the compressed gas.

When the valve body f of the switching valve 26 is at the position shown in FIG. 2, the drying process is performed by the B cylinder 4, and the pressure increasing process or the regeneration process is performed by the A cylinder 3. That is, the moist compressed air supplied to the dehumidifying device is guided from the inlet 10 of the inlet head 15 to the third port c of the switching valve 26 via the inlet path 30, and further via the fourth port d. It is guided into the B cylinder 4 from the B cylinder communication passage 32.

While the moist compressed air passes through the B cylinder 4 from the lower part to the upper part, a drying step is performed in which the adsorbent 17 filled therein absorbs and dehumidifies and dries the compressed air.
Then, the check valve 18B provided at the upper portion is pushed up, guided to the supply path 20 of the outlet head 5, and further supplied from the supply port 9 to a predetermined supply destination.

A part of the dry air flowing out of the upper opening of the B cylinder 4 is guided to the purge chamber 22, and the flow rate is further reduced by the purge orifice 12.
It is guided into the A-cylinder 3 via 2. Then, the moisture passes through the adsorbent 17 filled in the A cylinder 3 and desorbs the moisture adsorbed by the adsorbent 17 in the previous drying step.

The purge air, which is the air from which the moisture has been desorbed, is drawn out of the first port a from the A cylinder communication path 31 via the second port b, and is guided to the port communication path 33.
When the fifth port e is closed, the purge air is guided from the port communication path 33 to the purge branch path 34.

When the purge valve 27 is in the closed state, the purge air is shut off at this point, so that the pressure rises in the A cylinder 3 as a pressure increasing step. When the purge valve 27 is in the open state, the purge air passes through the purge valve 27 and is guided to the silencer 28, where the air is silenced and then released to the outside to constitute a regeneration step.

When the valve body f of the switching valve 26 is at the position shown in FIG. 3, the drying process is performed by the A cylinder 3 and the pressure increasing process or the regeneration process is performed by the B cylinder 4. That is, the moist compressed air supplied to the dehumidifying device is guided from the inlet 10 of the inlet head 15 to the third port c of the switching valve 26 via the inlet 30 and further via the second port b. It is guided from the A cylinder communication passage 31 into the A cylinder 3.

While the moist compressed air passes through the inside of the A-cylinder 3 from the lower portion to the upper portion, a drying step is performed in which the adsorbent 17 filled therein adsorbs and dehumidifies and dries. Then, the check valve 18A provided at the upper portion is pushed up and guided to the supply passage 20 of the outlet head 5, and further the supply outlet 9
Is supplied to a predetermined supply destination.

A part of the dry air derived from the upper end opening of the A cylinder 3 is guided to the purge chamber 22, the flow rate is reduced by the purge orifice 12, and the dry air flows through the purge chamber 22 above the B cylinder 4. It is guided into the cylinder 4.

This dry air passes through the adsorbent 17 filled in the B-cylinder 4 and, in the preceding drying step, adsorbent 1
7 desorbs the adsorbed moisture. The purge air, which is the air from which the moisture has been desorbed, is led out of the B cylinder communication passage 32 through the fourth port d through the fifth port e, and further guided into the port communication passage 33.

When the first port a is closed, the purge air flows from the port communication passage 33 to the purge branch passage 3.
It is led to 4. When the purge valve 27 is in the closed state, the purge air is shut off here, and a pressure increasing step is performed in which the pressure in the B cylinder 4 increases. When the purge valve 27 is in the open state, the purge air passes through the purge valve 27 and is guided to the silencer 28, where the air is silenced and then released to the outside to constitute a regeneration step.

Next, as shown in FIGS. 4A to 4D, the above-described dehumidifying operation will be described in order from the viewpoint of switching the channel configuration.

In FIG. 4A, the wet compressed air is guided to the B cylinder 4 through the switching valve 26, and is adsorbed and dried by the adsorbent 17 filled therein. The dried compressed air is supplied to the supply destination through the check valve 18B.

A part of the dry air flowing out of the B cylinder 4 is guided to the A cylinder 3 through the purge orifice 12, but the purge valve 27 is closed, and the pressure in the A cylinder 3 is increased to the operating pressure. . That is, the drying process is performed in the B cylinder 4, and the pressure increasing process is performed in the A cylinder 3.

In FIG. 4B, the switching valve 26 switches and the purge valve 27 changes to the open state. The wet compressed air is guided to the A cylinder 3 through the switching valve 26, and the adsorbent 17
For adsorption and drying.

The dry compressed air is discharged through a check valve 18A. A part of the dry air that has flowed out of the A cylinder 3 is guided to the B cylinder 4 through the purge orifice 12 to desorb moisture from the adsorbent.

The purge air is supplied to the opened purge valve 27.
And is guided to the silencer 28, from which it is discharged to the outside. That is, the drying process is performed in the A cylinder 3, and the regeneration process is performed in the B cylinder 4.

In FIG. 4C, the switching valve 26 is kept in the same state, while the purge valve 27 is changed to the closed state. Therefore, a drying step is performed subsequently in the A cylinder 3 and a pressure increasing step for increasing the pressure in the B cylinder 4 to the operating pressure is performed.

In FIG. 4D, the switching valve 26 is switched, and the purge valve 27 is changed to the open state. The wet compressed air is led to the B cylinder 4 via the switching valve 26, and is adsorbed and dried by the adsorbent 17 after the regeneration.

The dried compressed air is supplied through a check valve 18B. A part of the dry air that has flowed out of the B cylinder 4 is led to the A cylinder 3 through the purge orifice 12, becomes purge air in which moisture is desorbed from the adsorbent 17, and is sent from the silencer 28 through the purge valve 27. Released to the outside.
That is, the drying process is performed in the B cylinder 4, and the regeneration process is performed in the A cylinder 3.

Thereafter, the state is switched to the state shown in FIG. 4A again, and the above four steps are sequentially repeated.

During the standard operation, control as shown in FIG. 6 is performed. That is, since the control circuit 25 controls the switching valve 26 to switch at intervals of two minutes, the switching between the drying step in which the A cylinder 3 adsorbs and dehumidifies and the drying step in which the B cylinder 4 adsorbs and dehumidifies takes about two minutes. Done at intervals.

The control circuit 25 controls the opening of the purge valve 27 substantially at the same timing as the switching of the switching valve 26, and controls the closing of the purge valve 27 so as to be before the switching of the switching valve 26 next.

For example, the purge valve 27 is controlled to open several seconds after the switching valve 26 is switched to perform the drying step of adsorption and dehumidification in the A cylinder 3, and the pressure fluctuation when the regeneration purge in the B cylinder 4 is started is reduced. Suppress.

The purge valve 27 is set to be opened for about 90 seconds, during which the regeneration process in the B cylinder 4 is continued. Then, about 90 seconds after the start of the dehumidifying and drying of the A cylinder 3, the purge valve 27 is closed, so that the B cylinder 4 performs the pressure increasing step.

The pressurizing step is continued in the B cylinder 4 for about 30 seconds, and after a total of about 120 seconds (2 minutes), the drying step of switching the switching valve 26 to perform adsorption and dehumidification in the B cylinder 4 is continued for 120 seconds. A few seconds after this switching, the purge valve 27 is controlled to open, and the regeneration process is continuously performed on the side of the A cylinder 3 for about 90 seconds. Then, the purge valve 27 is closed for about 30 seconds, and the pressure increase step is performed on the side of the A cylinder 3. change.

Eventually, after continuing for about 120 seconds (2 minutes), the process is changed to the drying and adsorption / dehumidification on the side of the A cylinder 3 and the regeneration and pressurization on the side of the B cylinder 4 again as described above.
Repeat in the following order.

The humidity sensor 23 detects the humidity of the compressed air dried by adsorption and dehumidification and sends a detection signal to the control circuit 25, which calculates the dew point temperature (dew point under pressure) Ta, and outputs the result to the sensor output. Output as voltage.

For example, when the load supplied is small, such as when the amount of air required at the point supplied from the supply port 9 is extremely small, or when the humidity of the compressed air introduced from the introduction port 10 is extremely low, the air is dried. In this case, the operation shifts to energy saving operation.

In practice, switching from the standard operation to the energy-saving operation is performed based on the flowchart shown in FIG. That is, the standard operation is started in step S1 from the start. Moving from the standard operation to step S2, the humidity sensor 23 detects the humidity of the supplied dry air.

In step 3, the control circuit 25 having received the detection signal from the humidity sensor 23 calculates the dew point temperature (dew point under pressure) Ta. Then, in step S4, the control circuit 25 compares the preset dew point temperature (dew point under pressure) Ts stored in advance with the calculated dew point temperature Ta.

The calculated dew point temperature Ta is equal to the set dew point temperature Ts.
Lower than or equal to (Ta ≦ Ts)
When the determination is Yes, the process proceeds to step S5, and the energy saving operation described later is started. If the calculated dew point temperature Ta is higher than the set dew point temperature Ts, the result is No, and step S1 is performed.
Return to standard operation.

FIG. 7 shows the control in the energy saving operation. The set dew point temperature Ts stored in advance in the control circuit 25 is, for example, a pressure dew point of −40 ° C., and the calculated dew point temperature Ta
Is less than or equal to the set dew point temperature Ts, a start signal for energy saving operation is issued.

The switching valve 28 is used for dehumidifying and drying the A cylinder 3 and the B cylinder 4
And dehumidification and drying are switched at 2 minute intervals as described above. The purge valve 27 is opened to perform regeneration purging of the B cylinder 4 substantially at the same timing as the switching of the dehumidification / drying for the A cylinder 3, and then the purge valve 27 is closed to increase the pressure. Two minutes later, the regeneration purge of the A cylinder 3 is performed substantially in synchronization with the switching of the dehumidification and drying of the B cylinder 4, and then the pressure is increased.

When the load is very small or the humidity of the introduced compressed air is very low, the dew point temperature falls from -40.degree. C. to -45.degree. Further, the switching control for the switching valve 26 continues at intervals of two minutes,
Keeps the closed state. From this, A cylinder 3 and B cylinder 4
And wet compressed air is guided to the cylinders 3 and 4 so that the adsorbents 17 in the cylinders 3 and 4 perform the same adsorption function. for that reason,
The degree of dryness of the supplied dry air does not vary and is kept constant.

Since there is no purge of moisture desorbed from the adsorbent 17 by closing the purge valve 27, the dew point temperature Ta
Gradually rises again from -45 ° C. After the switching of the switching valve 26 is performed for a predetermined cycle (for example, three cycles: 12 minutes), the purge valve 27 is controlled during one cycle of the dehumidifying and drying switching of the A and B cylinders 3 and 4. You.

That is, the purge valve 27 is controlled in the fourth cycle based on the first switching cycle of the switching valve 26. More specifically, the regeneration purge of the B cylinder 4 is performed substantially in synchronization with the switching of the dehumidification and drying of the A cylinder 3,
The timing of the switching of the dehumidifying and drying of the B cylinder 4 is almost synchronized with the timing of A.
The regeneration purging of the cylinder 3 is performed.

From this, the moisture accumulated in each of the A and B cylinders 3 and 4 is forcibly purged by the repetition of dehumidification and drying during the energy saving operation, and the adsorption degree of the adsorbent 17 is recovered to some extent.

Thereafter, the switching valve 2 as described above is again used.
6 and the purge valve 27 every four cycles
Is performed. The above pattern does not change while the energy saving operation is continued.

A so-called energy saving operation is performed in which the amount of energy can be reduced by reducing the purge amount. Then, since the adsorbent 17 in each of the cylinders 3 and 4 is forcibly purged at every predetermined cycle, the deterioration of the adsorbent 17 is minimized.

When the load returns to the original state or the humidity of the compressed air introduced rises again, the set dew point temperature T
Since the calculated dew-point temperature Ta becomes higher than s, the control circuit 25 controls again to return to the above-described standard operation of the entire flow rate.

Even after returning to the standard operation, A,
Since the regeneration step of forcibly purging the desorbed moisture for the desorbent 17 in each of the cylinders 3 and 4 is performed, the dew point of the obtained dry air hardly fluctuates.

Further, during the energy saving operation, the deterioration of the adsorbent 17 in each of the A and B cylinders 3 and 4 proceeds uniformly.
Therefore, when replacement is necessary, the adsorbents 17 of the A and B tubes 3 and 4 may be replaced at the same time.

During the energy saving operation in which the regeneration process described above is stopped, the purge valve 27 is controlled to open every four cycles of the dehumidification / drying switching of the switching valves 26 for the cylinders A and B 3 and 4. However, the present invention is not limited to this.

As shown in FIG. 8A, the purge valve 27 may be controlled to be opened every five cycles of the dehumidification / drying switching, and the number of cycles may be determined, for example, by controlling the load condition by the dew point of the air after adsorption and drying. It can be appropriately changed according to various conditions such as judgment and response.

Further, during the energy saving operation, the switching of the dehumidifying / drying operation of the switching valve 26 for each of the A and B cylinders 3 and 4 is not necessarily limited to the alternate operation. For example, as shown in FIG. 8B, an energy-saving operation is performed in which the purge valve 27 is closed to stop the regeneration process, while the switching valve 26 is kept switched from the A cylinder 3 to the B cylinder 4. There may be.

However, even in this state, it is needless to say that the purge valve 27 must be opened and controlled in a predetermined cycle so that the adsorbent 17 in each of the cylinders 3 and 4 is evenly purged. is there.

[0080]

As described above, according to the present invention, during the so-called energy saving operation, the forced purge of the adsorbent of each adsorption column is performed in a predetermined cycle.
Deterioration of the adsorbent in both adsorption cylinders proceeds evenly while keeping the amount of dry air discharged by purging small, suppressing fluctuations in dew point temperature between adsorption cylinders when returning to standard operation. In addition to the improvement of the reliability, there is an effect that the replacement of the adsorbent of both adsorption cylinders is performed at the same time, unnecessary exchange is eliminated, and the running cost is reduced.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a dehumidifier showing one embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the dehumidifier, showing the embodiment.

FIG. 3 is a schematic cross-sectional view of the dehumidifier showing the embodiment, illustrating a process different from that in FIG. 2;

FIG. 4 is a view showing the same embodiment and explains the dehumidifying action in order from the switching of the channel configuration.

FIG. 5 is a flowchart showing the same embodiment, up to switching from standard operation to energy saving operation.

FIG. 6 is a view showing the embodiment and illustrating control during standard operation.

FIG. 7 is a diagram illustrating the embodiment and illustrating control during energy saving operation.

FIG. 8 is a diagram illustrating control during energy saving operation according to another embodiment.

FIG. 9 is a view for explaining conventional control during energy saving operation.

[Explanation of symbols]

 17 ... adsorbent, 3 ... adsorption cylinder (A cylinder), 4 ... adsorption cylinder (B cylinder), 26 ... switching valve (switching means), 27 ... purge means (purge valve), 23 ... humidity sensor, 25 ... control circuit (Control means) 30 ... Introduction path, 31 ... A cylinder communication path, 32 ... B cylinder communication path, 33 ... Port communication path, 34 ... Purge branch path.

Claims (3)

[Claims] 1. A drying step in which a wet compressed gas is introduced into one of two adsorption cylinders filled with an adsorbent to adsorb and dehumidify, and a part of the dry gas obtained in the drying step is used in a previous stage. A regeneration step of desorbing moisture from the adsorbent by guiding to the other adsorption column having reduced moisture absorption capacity in the drying step and purging the desorbed moisture from the adsorption column is performed in parallel, and these drying and regeneration steps are performed. In a method of dehumidifying a compressed gas for supplying a dry gas continuously by alternately switching between both adsorption columns, an energy saving operation for stopping the regeneration process under a predetermined condition is performed, and a predetermined cycle is performed during the energy saving operation. A method for dehumidifying compressed gas, wherein the regeneration step is performed in step (a). 2. The dehumidification of compressed gas according to claim 1, wherein during the energy saving operation, the drying step is alternately continued between the two adsorption cylinders, or only one of the adsorption cylinders is continued. Method. 3. An adsorbent-filled two adsorption cylinders, a communication path for communicating these adsorption cylinders via switching means, and a purging means are provided to guide wet compressed gas to one of the adsorption cylinders. A part of the dried gas is led to the other adsorption column to desorb moisture from the adsorbent whose hygroscopic capacity has decreased in the previous stage, and the desorbed moisture is purged from the adsorption column by the purge means. In a compressed gas dehumidifier for supplying dry gas continuously by alternately switching between drying and regeneration between both adsorption columns based on the switching of the switching means, under predetermined conditions. A compressed gas dehumidifier comprising a control means for performing an energy saving operation for stopping the regeneration step and performing a regeneration step in a predetermined cycle during the energy saving operation.