JP3517157B2 - Method and apparatus for dehumidifying compressed gas - 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 of dehumidifying a compressed gas in which a moist compressed gas is adsorbed and dehumidified using an adsorbent and then dried, and particularly to prevent early deterioration of the adsorbent. About energy-saving driving.

[0002]

2. Description of the Related Art In a conventional dehumidifying apparatus, two dry adsorption air is continuously supplied, and therefore 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. .

Wet compressed air is introduced into one of the adsorption cylinders to be adsorbed and dried, and supplied to a predetermined supply destination. At the same time, a part of the obtained dry air is introduced to the other adsorption cylinder, and moisture is desorbed from the adsorbent whose hygroscopic capacity has decreased by absorbing moisture in the previous stage, and this moisture is further purged from the adsorption cylinder. Eggplant In this regeneration step, about 20% of the obtained 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 simultaneously performed in parallel, and a switching valve provided between the adsorption cylinders is operated after a predetermined time has elapsed. Switch to supply dry air continuously.

By the way, since the dehumidifier is designed on the basis of the most harsh summer conditions in which the ambient temperature and the intake air temperature rise, the dehumidifier is adsorbed, for example, when it is used in winter or when the load on the supply destination is reduced. It is desirable to reduce the adsorption action of the agent to achieve this long 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 the purge valves connected to the adsorption cylinders are closed. For example, while the compressed air that has been wetted is guided only to the B cylinder to continue the drying for adsorption and dehumidification, the regeneration of both the A and B cylinders is stopped.

[0007]

In the energy saving operation, when the switching operation of the switching valve is stopped and all the purge valves connected to the adsorption cylinder are closed, the amount of dry air discharged by the purge is increased. Decreases. However, the energy saving operation described above may be continued for a long time depending on conditions. During this time, the adsorbent in one of the adsorption cylinders only performs the adsorption action, and the adsorbent in the other adsorption cylinder does not have any action.

Therefore, in the state of returning to the standard operation, the balance between the amount of adsorbed water of the adsorbent in the adsorption column that continues dehumidification and drying and the amount of adsorbed water of the adsorbent in the other adsorption column having no effect is poor. Become. Actually, the dew point temperature of the dry air supplied from the side where the dehumidifying and drying is continued becomes higher than the dew point temperature of the dry air supplied from the other side.

After all, the adsorbent on the side that has continued the adsorption action 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 one of the adsorbents deteriorates, both of them are generally replaced, and the other adsorbent becomes useless replacement, which adversely affects the running cost.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to reduce the discharge amount of dry air by purging to a small amount in both so-called energy-saving operation, while maintaining both adsorption cylinders. The deterioration of the adsorbent inside is promoted evenly, the fluctuation of the dew point temperature between each adsorption cylinder when returning to the standard operation is suppressed, and the adsorbent replacement timing is eliminated at the same time to eliminate wasteful replacement and running. An object of the present invention is to provide a dehumidification method for compressed gas and a device therefor, which contributes to cost reduction.

[0011]

In order to satisfy the above object, the method for dehumidifying a compressed gas according to the present invention is, as claimed in claim 1, that one of the two adsorbing cylinders filled with an adsorbent is moistened. A drying process that introduces compressed gas to adsorb and dehumidify it, and a part of the dry gas obtained by this drying process is introduced to the other adsorption column whose hygroscopic capacity has decreased in the previous drying process to desorb moisture from the adsorbent. Dehumidification of the compressed gas, in which the regeneration process of purging the desorbed moisture from the adsorption cylinder is performed in parallel, and the drying process and the regeneration process are alternately switched between the adsorption cylinders to continuously supply the dry gas. In the method, under a given condition, one of the adsorption cylinders carries out a drying step, and the other adsorption cylinder carries a part of the dry gas obtained by the one adsorption cylinder.
The adsorption process to remove the moisture from the adsorbent , and to stop the purging of the desorbed moisture, and to perform a drying process alternately between both adsorption cylinders.
Continue switching the regeneration process to stop the regeneration .

According to a second aspect of the present invention, in the method for dehumidifying compressed gas according to the first aspect, the predetermined condition is that the dew point temperature (pressure dew point) Ta of the dry gas obtained in the drying step is the set dew point temperature (under pressure). The dew point is equal to or lower than Ts (Ta ≦ Ts).

In order to satisfy the above object, the compressed gas dehumidifying device of the present invention is, as a third aspect, a two adsorption cylinders filled with an adsorbent, a communication passage communicating these adsorption cylinders through a switching means, and An adsorbent having a purging means, which guides a moist compressed gas to one of the adsorption cylinders to adsorb and dehumidify and dry it, and guides a part of the dried gas to the other adsorption cylinder to reduce the hygroscopic ability in the previous stage. The moisture is desorbed from the adsorption column and the desorbed moisture is purged from the adsorption column by the purging unit.The regeneration is performed in parallel.Drying and regeneration are alternately switched between the adsorption columns based on the switching of the switching unit. in dehumidifier supplies to dry gas, under predetermined conditions, to name a drying of moist compressed gas in one adsorption cylinder, one to the other adsorption column
Is it an adsorbent that guides a part of the dry gas obtained in one adsorption cylinder?
Control for the above switching means to desorb moisture from the
And continue to stop purging the desorbed moisture.
The control means for controlling the purging means is provided.

By adopting a means for solving such a problem , a drying process is performed in both adsorption cylinders under predetermined conditions ,
Dehumidify and stop purging of desorbed moisture
So-called energy-saving operation that continues switching the regeneration process
Even if the purge amount is suppressed to a small amount, the deterioration of both in-cylinder adsorbents can be progressed evenly, and the fluctuation of the dew point temperature between the adsorption cylinders when returning to standard operation can be suppressed, and the adsorbent replacement The timing can be taken at the same time.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a perspective view of the appearance of a decompressor for compressed gas. This dehumidifying device includes a pedestal 1 on the lower side, an electric component box 2 mounted on one side of the pedestal 1, and two adsorption cylinders mounted on the other side of the pedestal 1 (for convenience of explanation, Hereinafter, the left suction cylinder in the drawing will be referred to as the A cylinder, and the right suction cylinder in the drawing will be referred to as the B cylinder.) 3, 4 and the outlet head 5 mounted over the upper ends of these A and B cylinders 3, 4. , And an inlet head (not shown here) mounted over the lower ends of the A and B cylinders.

The outlet head 5 is attached and fixed to the pedestal 1 through a plurality of support 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 cover plate 8 attached to the gantry 1.

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

A humidity indicator 11 is provided at the center of the outlet head 5 and contains a member which comes into contact with the adsorbed and dried gas and changes its 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 the upper ends of both cylinders 3 and 4
Two are provided. A pair of connection ports 13 for connecting a purge valve described later are provided on the side opposite to the purge orifice 12.

FIG. 2 and FIG. 3 schematically show the cross section of the same adsorption device, which are in different states of action. Each of the A and B cylinders 3 and 4 is composed of a cylinder body whose upper and lower end surfaces are open. The upper end opening portion is inserted into the recess 5a provided on the lower surface of the outlet head 5, and the lower end opening portion is described above. It is fitted into a recess 15 a provided on the upper surface of the inlet head 15.

Then, the perforated plate 16 is provided at a position spaced from the upper end opening and the lower end opening of the A and B cylinders 3 and 4, respectively.
Is provided, 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 A in the outlet head 5,
Check valves 18A, 18 are provided at positions facing the central portions of B cylinders 3, 4
A valve chamber 19 that accommodates B is formed. These check valves 18
A and 18B allow the gas flow upward from the inside of the cylinders 3 and 4 on the lower side, and prevent the gas flow from the upper part into the cylinders 3 and 4.

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

Around the respective valve chambers 19, recesses are formed within the range where the A and B cylinders 3 and 4 are fitted, and the purge orifice described above (here, it is drawn so as to be provided in the outlet head 5 is drawn. The purge chamber 22 communicates with the (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 / discharge path 20 opposite to the supply / discharge port 9 is closed, and a humidity sensor 23 is attached therethrough. As shown only in FIG. 3, a control circuit 25 serving as control means is housed in the electric component box 2 and electrically connected to the humidity sensor 23. The humidity sensor 23 detects the humidity of the dry air in the feed passage 20 and sends the detection signal to the control circuit 25.

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

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

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

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

The inlet head 15 has an inlet 1
0 and the third port c of the switching valve 26 are communicated with each other, an A cylinder communication passage 31 that communicates the lower opening end of the A cylinder 3 with the second port b, and a lower opening of the B cylinder 4. B cylinder communication passage 32 that connects the end and the fourth port d, and the first port a
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 opening / closing valve having a normal structure, and is electrically connected to the control circuit 25.
It opens and closes in accordance with a control signal from the control circuit 25 to conduct or block the purge gas introduced from the purge branch passage 34. The purge gas derived from here is guided to the silencer 28 to be silenced, and then discharged to the outside.

The control circuit 25 controls the humidity sensor 23.
A circuit for receiving the detection signal from the unit and converting it to a dew point temperature (pressure dew point) Ta, a circuit for comparing this dew point temperature Ta with a preset dew point temperature (pressure dew point) Ts, and the comparison result. Based on the above, the switching valve 26
And a circuit for controlling opening / closing of the purge valve 27.

An adsorption device having such a structure,
It operates as described below. It should be noted that compressed air is applied as the compressed gas in the description.

When the valve body f of the switching valve 26 is in the position shown in FIG. 2, the B cylinder 4 performs the drying process and the A cylinder 3 performs the pressurizing process or the regenerating process. That is, the moist compressed air supplied to the dehumidifier is guided from the inlet 10 of the inlet head 15 to the third port c of the switching valve 26 via the inlet passage 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 inside of the B cylinder 4 from the lower part to the upper part, the adsorbent 17 filled therein adsorbs and dehumidifies it to dry it.
Then, the check valve 18B provided at the upper portion is pushed up to be guided to the supply passage 20 of the outlet head 5, and further supplied from the supply outlet 9 to a predetermined supply destination.

A part of the dry air discharged from the upper end opening of the B cylinder 4 is introduced into the purge chamber 22, and the flow rate is throttled by the purge orifice 12, so that the purge chamber 2 above the A cylinder 3 is filled.
It is guided into the A cylinder 3 via 2. Then, it passes through the adsorbent 17 filled in the A cylinder 3 to desorb the moisture adsorbed by the adsorbent 17 in the drying process of the previous stage.

The purge air, which is the air from which moisture has been desorbed, is led out from the A-cylinder communication passage 31 through the second port b through the first port a and is introduced into the port communication passage 33.
From the place where the fifth port e is in the closed state, the purge air is guided from the port communication passage 33 to the purge branch passage 34.

When the purge valve 27 is in the closed state, the purge air is cut off here, so that the pressure in the A cylinder 3 rises. 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 it is silenced and then released to the outside.

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

While the moist compressed air passes through the inside of the A cylinder 3 from the lower part to the upper part, the adsorbent 17 filled therein adsorbs and dehumidifies the material to dry it. Then, the check valve 18A provided at the upper portion is pushed up to be guided to the feed passage 20 of the outlet head 5, and further, the feed outlet 9
Is supplied to a predetermined supply destination.

A part of the dry air discharged from the upper end opening of the A cylinder 3 is guided to the purge chamber 22, and the flow rate is reduced by the purge orifice 12, and the dry air is discharged from the purge chamber 22 above the B cylinder 4 to the B chamber 4. Guided in the cylinder 4.

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

From the place where the first port a is closed, the purge air is supplied from the port communication passage 33 to the purge branch passage 3.
Guided to 4. When the purge valve 27 is closed, the purge air is cut off here, and the pressure in the B cylinder 4 rises. 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 it is silenced and then released to the outside.

Next, as shown in FIGS. 4A to 4D, the above dehumidifying action will be described in order from the aspect of switching the flow path configuration.

In FIG. 4A, the moist 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 discharged from the B cylinder 4 is guided to the A cylinder 3 via the purge orifice 12, but the purge valve 27 is closed and the inside of the A cylinder 3 is pressurized to the operating pressure. . That is, the B cylinder 4 performs the drying process, and the A cylinder 3 performs the pressurizing process.

In FIG. 4B, the switching valve 26 is switched and the purge valve 27 is opened. The moist compressed air is guided to the A cylinder 3 through the switching valve 26, and the adsorbent 17
By adsorption and drying.

Dry compressed air is delivered through the check valve 18A. A part of the dry air discharged from the A cylinder 3 is guided to the B cylinder 4 through the purge orifice 12 to desorb the moisture from the adsorbent.

The purge air is released from the purge valve 27.
Is guided to the silencer 28, and is discharged to the outside from here. That is, the A cylinder 3 performs the drying process and the B cylinder 4 performs the regeneration process.

In FIG. 4 (C), the switching valve 26 maintains the same state, while the purge valve 27 changes to the closed state. Therefore, the A cylinder 3 is subsequently subjected to the drying process, and the B cylinder 4 is subjected to the pressure increasing process of increasing the pressure to the operating pressure.

In FIG. 4D, the switching valve 26 is switched and the purge valve 27 is changed to the open state. The moist compressed air is guided to the B cylinder 4 via the switching valve 26, and is adsorbed and dried by the adsorbent 17 that has finished regeneration.

The dried compressed air is supplied via the check valve 18B. A part of the dry air discharged from the B cylinder 4 is guided to the A cylinder 3 through the purge orifice 12 to become the purge air in which moisture is desorbed from the adsorbent 17, and the purge air is discharged from the silencer 28 via the purge valve 27. It is released to the outside.
That is, the B cylinder 4 performs the drying process, and the A cylinder 3 performs the regeneration process.

After that, the state is changed to the state of FIG. 4A again, and the above four steps are sequentially repeated.

During the standard operation, the control as shown in FIG. 6 is performed. That is, since the control circuit 25 controls the switching valve 26 to switch at an interval of 2 minutes, the switching between the drying process for adsorbing and dehumidifying in the A cylinder 3 and the drying process for adsorbing and dehumidifying in the B cylinder 4 takes about 2 minutes. Done at intervals.

Then, the control circuit 25 controls the opening of the purge valve 27 at substantially the same timing as the switching of the switching valve 26, and controls the closing of the purge valve 27 before the switching valve 26 is switched next time.

For example, the purge valve 27 is controlled to be opened a few seconds after the switching valve 26 is switched to perform the drying process of adsorption and dehumidification in the A cylinder 3, and the pressure fluctuation when the regeneration purge in the B cylinder 4 is started. Suppress.

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

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

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

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

For example, when the so-called load is small, for example, the amount of air required at the destination supplied from the supply outlet 9 is very small, or the humidity of the compressed air introduced from the inlet 10 is extremely low and dry. In this case, shift to energy saving operation.

Actually, based on the flow chart as shown in FIG. 5, the switching is made from the standard operation of the total flow rate to the energy saving operation of the small flow rate. That is, the standard operation is started in step S1 from the start. From this standard operation, the process moves to step S2, and the humidity sensor 23 detects the humidity of the dry air supplied.

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

The calculated dew point temperature Ta is the set dew point temperature Ts.
Lower than or equal to (Ta ≦ Ts),
If Yes, the process moves to step S5, and the energy saving operation described later is started. Further, if the calculated dew point temperature Ta is higher than the set dew point temperature Ts, the determination result is No and the step S1 is performed.
Return to normal 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 calculated.
Is equal to or lower than this set dew point temperature Ts, the energy saving operation start signal is issued below.

The switching valve 28 is used for dehumidifying and drying the A cylinder 3 and the B cylinder 4.
The dehumidifying / drying is switched at intervals of 2 minutes as described above. Then, the purge valve 27 is opened to perform the regeneration purge of the B cylinder 4 almost at the same timing as the switching of the dehumidifying and drying to the A cylinder 3, and then the purge valve 27 is closed to increase the pressure. After 2 minutes, the regeneration purge of the A cylinder 3 is performed almost at the same timing as the switching of the dehumidifying and drying of the B cylinder 4, and then the pressure is increased.

Since the load is very small or the humidity of the introduced compressed air is very low, the dew point temperature drops from -40 ° C to -45 ° C. Further, although the switching control for the switching valve 26 continues every two minutes, the purge valve 27
Holds the closed state. From this, the A cylinder 3 and the B cylinder 4
The moist compressed air is introduced almost uniformly to the adsorbents 17 in the cylinders 3 and 4 so as to have the same adsorbing action. for that reason,
The dryness of the supplied dry air does not change and is kept constant.

Since there is no purge of the moisture desorbed from the adsorbent 17 due to the closing of the purge valve 27, the dew point temperature Ta
Gradually rises again from -45 ° C. After such switching of the switching valve 26 is performed for a predetermined cycle (for example, 3 cycles: 12 minutes), the purge valve 27 is once opened.

The purge valve 27 is opened only for one cycle of the switching valve 26, for example. That is, the B cylinder 4 is almost timed with the switching of the dehumidifying and drying of the A cylinder 3.
The regeneration purge is performed, and the regeneration purge of the A cylinder 3 is performed almost at the same timing as the switching of the dehumidifying and drying of the B cylinder 4.

Therefore, by repeating the dehumidifying and drying during the energy saving operation, the moisture accumulated in the A and B cylinders 3 and 4 is purged, and the adsorption degree of the adsorbent 17 is recovered to some extent. Then, the switching control of the switching valve 26 as described above is continued and the purge valve 27 is closed during the predetermined cycle.

By switching to such energy saving operation,
The amount of purge is reduced, and energy loss is reduced.
The deterioration of the adsorbent 17 is suppressed to a minimum since the cylinders 3 and 4 are purged every predetermined cycle.

When the load returns to the original state or the humidity of the compressed air introduced again rises, 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 standard operation of the full flow rate described above.

Even after returning to the standard operation, A,
B Since dehumidifying and drying were continued evenly in each of the cylinders 3 and 4,
There is almost no change in the dew point of the dry air obtained in the dehumidifying and drying process of each other.

Further, during the energy saving operation, the deterioration of the adsorbent 17 in the A and B cylinders 3 and 4 progresses evenly,
Therefore, when it is necessary to replace the adsorbent 17, the adsorbents 17 of the A and B cylinders 3 and 4 may be replaced at the same time.

The above is the description of the energy-saving operation in which the load is very small and dehumidified and dried compressed air is supplied only at a small flow rate. The energy-saving operation at a small flow rate and the standard operation at the full flow rate described above are performed. The energy saving operation at a so-called medium flow rate during the period will be described below.

As shown in FIG. 8, the switching valve 26 is switched every 2 minutes to continue the dehumidifying and drying process in the A and B cylinders 3 and 4 alternately. On the other hand, it is judged that the calculated dew point temperature Ta is equal to or lower than the set dew point temperature Ts, and the energy saving operation is started. That is, the purge valve 27 is closed at substantially the same timing as the switching of the dehumidifying and drying of the A cylinder 3.
The regeneration purge in the B cylinder 4 is interrupted.

However, since the load is large to some extent, the dew point temperature Ta becomes higher than the set dew point temperature Ts due to the interruption of the regeneration purge. Therefore, the purge valve 27 is opened almost at the same timing as the switching of the dehumidifying / drying of the B cylinder 4 to perform the regeneration purge in the A cylinder 3.

Then, since the dew point temperature Ta becomes lower than the set dew point temperature Ts again, the purge valve 27 is closed at the same timing as the dehumidification / drying switching of the A cylinder 3, and the regeneration purge of the B cylinder 4 is interrupted.

In the following, the energy saving operation at the medium flow rate is performed every time the dew point Ta rises above the set dew point temperature Ts during the four cycles of the dehumidifying / drying switching of the A and B cylinders 3 and 4 of the switching valve 26. 27 is opened to perform regeneration purge in the corresponding cylinders 3 and 4. As a result, the dew point fluctuation when returning to the standard operation is suppressed as much as possible, which is exactly the same as the energy saving operation with the small flow rate described above.

Further, although not shown in the drawing, it is possible to perform ranking even in energy saving operation with a small flow rate, depending on conditions. That is, in the energy saving operation of the small flow rate described above, the purge valve 27 is opened every four cycles of the dehumidification / drying switching for the A and B cylinders 3 and 4 of the switching valve 26, but the invention is not limited to this. is not.

The preset dew point temperature Ts stored in advance is set to a lower value, for example, a pressure dew point of −60 ° C. or −80 ° C. as a reference, and the dehumidifying / drying of the switching valve 26 is switched every 6 cycles or 8 cycles. An energy-saving operation with a smaller flow rate may be performed such that the purge valve 27 is once opened.

[0082]

According to the present invention as described above, according to the present invention, where
Under constant conditions, dehumidify and dry both purge cylinders and stop purging again.
Since the so-called energy-saving operation is performed to continue the raw switching, the deterioration of the adsorbent in both adsorption cylinders will progress evenly while suppressing the amount of dry air discharged by purging to a standard level. It suppresses the fluctuation of dew point temperature between each adsorption cylinder when returning and improves the reliability, and at the same time, the adsorbents of both adsorption cylinders are replaced at the same time to eliminate wasteful replacement and contribute to the reduction of running cost. It has the effect of doing.

[Brief description of drawings]

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

FIG. 2 is a schematic cross-sectional view of a dehumidifying device showing the same embodiment.

FIG. 3 is a schematic cross-sectional view of a dehumidifying device showing the same embodiment, illustrating a step different from that in FIG. 2;

FIG. 4 is a view for explaining the dehumidifying action in the same embodiment in order from the switching of the flow path configuration.

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

FIG. 6 is a view for explaining control during standard operation, showing the same embodiment.

FIG. 7 is a view for explaining control during energy saving operation at a small flow rate, showing the same embodiment.

FIG. 8 is a diagram illustrating control during energy saving operation at a medium flow rate according to the embodiment.

FIG. 9 is a diagram illustrating 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 route, 31 ... A cylinder communication passage, 32 ... B cylinder communication passage, 33 ... Port communication passage, 34 ... Purge branch.

Claims (3)

(57) [Claims] 1. A drying step of introducing a moist compressed gas into one of the two adsorption columns filled with an adsorbent to adsorb and dehumidify it, and a part of the dried gas obtained by this drying step. In parallel with the regeneration step of leading the other adsorption column whose hygroscopic capacity has decreased in the drying step in the previous stage to desorb moisture from the adsorbent and purge the desorbed moisture from the adsorption column,
In the method for dehumidifying a compressed gas in which a drying gas and a regeneration process are alternately switched between both adsorption cylinders to continuously supply a dry gas, one adsorption cylinder forms a drying step under the predetermined conditions, and the other Of the dry gas obtained by one of the adsorption tubes
A part of the adsorbent is used to desorb moisture, and a desorption process is also performed to stop the purging of the desorbed moisture.Also, a drying process is performed alternately between both adsorption cylinders, and moisture is desorbed from the adsorbent to remove moisture.
A method for dehumidifying a compressed gas, which is characterized in that the switching of the regeneration process for stopping the minute purge is continued. 2. The predetermined condition is that the dew point temperature (pressure dew point) Ta of the dry gas obtained in the drying step is equal to or lower than the set dew point temperature (pressure dew point) Ts (Ta ≦
The method for dehumidifying a compressed gas according to claim 1, wherein the method is Ts). 3. An adsorbent filled with two groups of adsorbents, a communication passage for connecting these adsorbents via a switching means and a purging means, and introduces a moist compressed gas into one of the adsorbents. Adsorption dehumidification and drying, part of this dry gas is guided to the other adsorption cylinder to desorb moisture from the adsorbent whose hygroscopic capacity has decreased in the previous stage and to purge the desorbed moisture from the adsorption cylinder by the purging means. In a dehumidifier for compressed gas, which continuously supplies dry gas by alternately switching drying and regeneration between both adsorption cylinders based on the switching of the switching means, under a predetermined condition. , to name a drying of moist compressed gas in one adsorption cylinder, obtained in one adsorption column to another adsorption column
To guide some of the dry gas to desorb moisture from the adsorbent
Continue the control of the switching means and attach / detach
Control the purging means to stop the purging of the accumulated moisture
A dehumidifying device for compressed gas, comprising: