JP2000297797A - Compressed air manufacturing apparatus and dehumidifying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the economy during operation by reducing the power consumption in a compressed air manufacturing device. SOLUTION: In this compressed air manufacturing apparatus having a compressor 1 and a drier 22a, the compressor 1 is driven by an electric motor 2. A part of the compressed air compressed by the compressor and cooled by an intercooler 11a is used for cooling the electric motor 2. The air cooling the electric motor is lead to an adsorption type drier 22a and the adsorbent filling the adsorption cylinder 23 of the drier 22a is heated and regenerated by the cooled air. This constitution can shorten the operation time of blower 25 and reduce the power consumption of the electric heater 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed air producing apparatus having an air compressor driven by an electric motor and an adsorption dryer, and a method for dehumidifying compressed air generated by the apparatus.

[0002]

2. Description of the Related Art Various methods have conventionally been employed for cooling an apparatus having a compressor. For example, an example in which an air compressor driven by an electric motor uses a part of compressed air to cool the electric motor is disclosed in JP-A-9-30818.
9 and JP-A-10-89296.

Further, in a refrigerator having a compressor having a drive shaft supported by magnetic bearings, a condenser and an evaporator, a part of the refrigerant circulating in a refrigeration cycle formed in the refrigerator or cooled by the refrigerator. Example of using a part of the cooling medium that has been used for cooling the power amplifier that constitutes the control system of the magnetic bearing,
It is disclosed in Japanese Utility Model Laid-Open No. 3-19499.

By the way, an adsorption type dryer is used to remove moisture from the compressed gas. As the adsorption type dryer, "Pneumatic Pneumatic Handbook", pages 513 to 517, edited by The Japan Hydraulic and Pneumatics Society. As described on the page, it is known that two adsorption cylinders each containing an individual adsorbent such as silica gel or activated alumina are used, and the adsorption and desorption of water are alternately repeated to dehumidify continuously. . This adsorptive dryer uses the method of desorbing moisture (regenerating adsorbent)
It is roughly classified into a heating regeneration type and a non-heating regeneration type.

In the desorption method of the heat regeneration type, a blower and a heater are used, and the regeneration air taken in from the outside is heated to 150 ° C. to 30 ° C.
Heated to 0 ° C. Then, the heated air is ventilated into the adsorption cylinder to be desorbed. Thereby, the temperature of the adsorbent is increased to enable regeneration. On the other hand, in the case of the non-heating regeneration type, a part of the dry air which has once passed through the dryer is introduced into the adsorption column to be desorbed. As a result, the adsorbent is exposed to a low steam partial pressure atmosphere to enable regeneration.

[0006]

In the cooling of the compressor described in the above publication, when a part of the air compressed by the air compressor is used for cooling the drive motor, it is supplied to a plant to which the compressor is connected. In order to secure the required air flow, it is necessary to increase the operating air flow of the compressor by the air flow used for cooling the electric motor. As a result, the compressor power increases.

On the other hand, regarding a dryer for dehumidification,
When a heating regeneration type dryer is used, regeneration air of about 4% to 10% of the handling air volume of the dryer is required for regeneration of the adsorbent. Further, a blower is required to blow the regeneration air, and an electric heater is required to heat the regeneration air. Therefore, the driving power of the blower and the electric power of the heater are required. On the other hand, when a non-heat regeneration type dryer is used, although no new power is required, the compressed air once passed through the dryer and dried is used as the regeneration air. About 30% is consumed in the regeneration air.

As described above, when the compressor and the dryer are separately installed, the amount of air used for cooling the motor and the amount of air required for operating the dryer are required. Further, in the heating and regeneration type dryer, the required air amount does not increase so much, but electric power for heating the regeneration air by the electric heater is required. All of these are uneconomical.

The present invention has been made in view of the above-mentioned disadvantages of the prior art, and has as its object to reduce the power cost during operation in a compressed air producing apparatus having an air compressor driven by an electric motor and an adsorption type dryer. An object of the present invention is to improve economic efficiency by reducing the amount. Another object of the present invention is to reduce the consumption of compressed air in a compressed air producing apparatus having an air compressor driven by an electric motor and an adsorption type dryer. Still another object of the present invention is to realize a compressed air producing apparatus having a simple configuration and improved economy.

[0010]

A first feature of the present invention to achieve the above object is to provide an air compressor having an electric motor and a centrifugal impeller attached to an end of a rotating shaft of the electric motor. A compressed air producing apparatus having a dryer for dehumidifying the air compressed by the air compressor, a cooling means for cooling the compressed air compressed by the compressor, and one of the compressed air cooled by the cooling means. It is an object of the present invention to provide a first flow path for extracting a portion and guiding the electric motor to the motor, and a second flow path for guiding compressed air that has cooled the electric motor to the dryer.

The dryer is an adsorption type dryer having a blower, and is provided with switching means for switching between air introduced from an electric motor and air supplied from the blower when the adsorbent contained in the dryer is regenerated. Is desirable. Further, a flow rate adjusting means for adjusting the amount of compressed air guided to the dryer may be provided in the first flow path.

A second feature of the present invention for achieving the above object is a dehumidifying method for dehumidifying compressed air compressed by a compressor having a centrifugal impeller attached to a motor shaft end by a dryer. In the on-road operation, the air cooled by the electric motor is guided to the dryer to regenerate the adsorbent, and when the compressor is in the unload operation, the adsorbent is regenerated by air from the blower provided in the dryer.

A third feature of the present invention to achieve the above object is that an air compressor having an electric motor and a centrifugal impeller attached to an end of a rotating shaft of the electric motor, In a compressed air producing apparatus provided with a dryer for dehumidifying compressed air, a first cooling means for cooling compressed air compressed by an air compressor, and a first means for guiding the compressed air cooled by the cooling means to an electric motor or a dryer. There is provided a pipe and a second pipe for connecting the motor and the dryer to flow the compressed air which has cooled the motor or regenerated the adsorbent in the dryer.

It is preferable that a three-way valve is provided in the second pipe, and the three-way valve and the first pipe are connected by a third pipe. Further, the electric motor is an electric motor driven by an inverter, and it is preferable to provide a pipe for guiding the compressed air obtained by regenerating the adsorbent in the dryer to a control panel of the inverter. Further, a pipe may be provided in which the rotating shaft is supported by a magnetic bearing, and the compressed air obtained by regenerating the adsorbent in the dryer is led to a control panel of the magnetic bearing.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several embodiments of the compressed air producing apparatus of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a first embodiment of a compressed air producing apparatus according to the present invention, and is a system diagram of a schematic configuration thereof. The compressed air producing apparatus includes a two-stage centrifugal air compressor and a heating / regenerating adsorption dryer. The compressors 1a and 1b that constitute the first and second stages of the two-stage centrifugal compressor 1 have centrifugal impellers 4a and 4b attached to both ends of the rotating shaft 3, respectively. An electric motor 2 is formed in an intermediate portion. The rotating shaft 3 is supported by radial magnetic bearings 6 a and 6 b and an axial magnetic bearing 7, and is driven by the high-speed motor 2 to rotate at high speed.

In the two-stage centrifugal compressor 1 configured as described above, the suction air 8 sucked into the first stage compressor 1a is guided from the outside atmosphere to a suction port via a required device such as a suction filter (not shown). . The air pressurized by the first stage compressor 1a is guided to the intercooler 11a, cooled, and then guided to the second stage compressor 1b. The air further pressurized by the second stage compressor 1b is guided to an aftercooler 11b, cooled, and supplied to a demand source downstream of the compressor 1 via a check valve 12. Here, the intercooler 11a and the aftercooler 11b may be formed integrally with the compressor casing, or may be provided separately.

The motor 2 for driving the compressor generates heat due to copper loss and iron loss of the motor stator 5 and the magnetic bearings 6a, 6b, 7 and wind loss around the rotating shaft 3 rotating at high speed. The intercooler 11a and the aftercooler 11
b, a part of the compressed air cooled is
8 and is supplied to the inside of the electric motor 2.

The cooling air supplied to the electric motor 2 cools the periphery of the electric motor stator 5 and the magnetic bearings 6a, 6b, 7 and then is exhausted out of the compressor 1. The temperature of the exhaust 19 at this time is a high temperature of about 90 ° C. to 120 ° C. Note that when the compressor 1 is in the unload operation state, the blow-off valve 13 is open. At this time, the control valve 14 is opened to secure the supply pressure of the cooling air.

The discharge air discharged from the compressor 1 is supplied to a pipe 9
, And is cooled by the aftercooler 11b, so that the relative humidity is high. Therefore, a dryer 22a is installed downstream of the compressor 1 in order to prevent generation of drain in a plant to which compressed air is supplied. Dryer 2
Reference numeral 2a denotes a heat regeneration type adsorption type dryer,
Solid adsorbents such as silica gel, activated alumina, and synthetic zeolite are filled in 3a and 23b. Dryer 22
The compressed air introduced into a is switched by the switching valves 24a and 24b so as to pass through one of the two suction tubes (the suction tube 23b in FIG. 1). Then, the moisture in the air is absorbed by the adsorbent in the adsorption column, and is supplied to the plant from the pipe 10 as dry air.

When the adsorbent absorbs a certain amount of water, it cannot be sufficiently adsorbed, and the dew point of the discharged air increases. For this reason, conventionally, the adsorption type dryer has a plurality of, in most cases, two adsorption columns, and when one adsorption column is adsorbing the handling air, the other adsorption column is regenerating the adsorbent. In order to regenerate the adsorbent, the temperature of the adsorbent is increased in the case of a heat regeneration type dryer. This is realized by heating the air blown from the blower by an electric heater and passing the air through an adsorption cylinder in a regeneration process.

Further, as described above, the amount of air required for regeneration of the adsorbent reaches 4% to 10% of the air flow handled by the dryer. The regeneration temperatures of silica gel and activated alumina are 150 ° C. to 180 ° C. and 170 ° C. to 30 ° C., respectively.
It is as high as 0 ° C. After regenerating the adsorption cylinder for a certain time,
Turn off the electric heater. Then, after the adsorbent has sufficiently cooled, the switching valve is operated to alternate the path of the compressed air to the two adsorption columns, thereby continuously producing dry air.

Since this conventional cooling and dehumidifying method is uneconomical, in the present invention, the cooling air which has been cooled and exhausted to the outside of the machine is effectively used. That is, the cooling air that has cooled the electric motor of the compressor 1 is supplied to the pipe 19,
Next, the air is led to the dryer 22a and is used as the regeneration air 28 of the dryer 22a. Therefore, when the compressor is performing the on-load operation, the three-way valve 30 is connected to the dryer side, and the air heated to about 90C to 120C is supplied to the dryer. Here, the valve 31 regulates the amount of air supplied to the dryer 22a. The supplied regeneration air is heated to a predetermined temperature by an electric heater 27 via a three-way valve 26. Thereafter, in the example of FIG. 1, the switching valves 24a and 24b guide the fluid toward the adsorption cylinder 23a to regenerate the adsorbent. After passing through the adsorption cylinder 23a, the gas is discharged from the exhaust pipe 29 to the atmosphere as wet dryer exhaust.

After regenerating the dryer for a predetermined time,
The three-way valve 30 is connected to the atmosphere to sufficiently cool the adsorbent. Then, the power supply to the electric heater 27 is stopped, and the three-way valve 26 is switched again to operate the blower 25. Thereafter, the switching valves 24a and 24b are operated to operate the cooling air adsorption cylinder 23.
a, switch the route to 23b. Next, the three-way valve 3
0, 26, the state of the electric heater 27 and the blower 25 are restored. Thereby, the adsorption cylinder is continuously regenerated.

When the compressor 1 is in the unloading operation, the three-way valve 30 is connected to the atmosphere side and the cooling air is supplied to the dryer 22a because the amount of exhaust air flowing through the pipe 19 is not sufficient. do not do. Therefore, the blower 25 is operated as a regeneration air source. Regeneration air is supplied from the blower 25 through the three-way valve 26 and the electric heater 27 to the adsorption column in the regeneration process. At this time, since the temperature of the air blown from the blower 25 is lower than that of the air in the pipe 19, the output of the electric heater 27 is automatically adjusted to a higher output than the air in the pipe 19.

According to the above-described embodiment, the operating time of the blower 25 can be reduced because the cooling air obtained by cooling the electric motor of the compressor 1 is effectively used for the regeneration of the adsorbent of the dryer 22a. 27 can be reduced. As a result, the compressed air production device can be operated economically. In this embodiment, a magnetic bearing is used as a bearing for supporting the rotating shaft, but it goes without saying that a ball bearing or an oil bearing may be used. Although not shown in FIG. 1, an air filter, a pressure gauge, and the like may be appropriately installed.

Next, another embodiment of the compressed air producing apparatus according to the present invention will be described with reference to FIG. In this embodiment,
The compressed air producing apparatus is provided with a two-stage centrifugal air compressor and a non-heat regenerative adsorption dryer. FIG. 2 is a schematic flow chart thereof. This embodiment is different from the embodiment shown in FIG. 1 in that a cooling air introduction path of the electric motor 2 and a non-heat regenerative adsorption type dryer are provided.

The air discharged from the compressor 1 is guided to an aftercooler 11b via a pipe 9. And aftercooler 11
It cools by b, and it will be in the state where relative humidity is high. A dryer 22b is provided downstream of the compressor 1 in order to prevent drainage in the plant. Here, the dryer 22b is a non-heating regenerative adsorption type dryer, and the adsorption cylinders 41a and 41b are filled with a solid adsorbent such as silica gel, activated alumina, or synthetic zeolite. The compressed air guided to the dryer 22b is guided to one of the two adsorption cylinders (41a in FIG. 2) by the three-way valves 33a and 33b. In the compressed air guided to the adsorption cylinder, moisture is absorbed by the adsorbent in the adsorption cylinder, and is supplied from the discharge pipe 10 to the downstream plant equipment as dry air.

At this time, a part of the dry air is
Is supplied to the adsorption cylinder 41b via the. The adsorbent in the adsorption cylinder 41b is exposed to the low steam partial pressure atmosphere by the dry air, and the regeneration of the adsorbent proceeds.

Even in the non-heat regeneration type dryer, the compressed air can be continuously dried by alternately repeating the adsorption and regeneration functions in the two adsorption cylinders. Non-heated dryer regeneration air volume is 15% to 30% of the dryer flow rate
%, Which is more than that of a heated dryer. In addition, since regeneration is performed with dry air, there is an advantage that it is not necessary to heat the regeneration air.

Heretofore, the air from which the dryer has been regenerated has been discharged to the atmosphere. In the present embodiment, the moist air exhausted from the dryer 22b is guided to the cooler 36 via the pipe 29, and is cooled by the cooler 36 and the drain 38 is separated. Then, the cooling air is supplied to the inside of the motor 2 through the three-way valve 42 as cooling air 37 for cooling the motor, and after cooling the motor, the cooling air is discharged from the discharge pipe 19 to the atmosphere. Further, when the amount of air discharged from the dryer 22b is larger than the amount of air required for cooling the motor, excess air is discharged to the atmosphere via the relief valve 43. One opening of the three-way valve 42 is connected to the pipe 9 via the pipe 9a.

When the compressor 1 is performing the unload operation, the blow-off valve 13 is opened to stop the supply of the compressed air to the dryer. Therefore, no exhaust of the regeneration air occurs. Therefore, during the unload operation, the three-way valve 42 is switched, and air for cooling the electric motor is extracted from an intermediate portion between the aftercooler 11a and the discharge check valve 12. At this time, the piping 37
Connects the three-way valve 42 and the electric motor 2 to guide cooling air to the electric motor 2.

According to the present invention, the air obtained by regenerating the adsorbent of the dryer 22a is effectively used as air for cooling the electric motor provided in the compressor 1. Thereby, the consumption of the compressed air in the compressor and the dryer can be reduced. Further, the economical efficiency of the operation of the compressor can be improved.

Also in this embodiment, it goes without saying that a ball bearing or an oil bearing may be used as a bearing for supporting the rotary shaft, and it goes without saying that an air filter, a pressure gauge and the like may be appropriately installed.

Another embodiment of the present invention will be described with reference to FIG. This embodiment is different from the embodiments shown in FIGS. 1 and 2 in that the compressor is a single-stage compressor and the electric motor is driven by an inverter. FIG. 3 is a schematic flow diagram showing an example of a compressed air producing apparatus provided with a single-stage centrifugal air compressor and a non-heating regenerative adsorption dryer.
In the single-stage centrifugal compressor 1, an impeller 4 a
The rotating shaft 3 is driven by the electric motor 2. The electric motor 2 is a high-speed electric motor driven by the inverter device 44. The rotating shaft 3 is supported by radial magnetic bearings 6a and 6b and an axial magnetic bearing 7, and each magnetic bearing is controlled by a magnetic bearing control panel 45. Other points are the same as those of the embodiment shown in FIG.

In this embodiment, the electric motor is driven by the inverter device, and a magnetic bearing is used as the bearing. Heretofore, in order to prevent the power elements and the like from generating heat and becoming high in temperature, an electric cooling fan has been installed in a housing that houses the inverter control panel. Also, a fan was similarly provided on the control panel of the magnetic bearing to forcibly cool it. According to the present invention, the branch pipe 3 branching from the pipe 37 for guiding the cooling air for cooling the electric motor.
7a is connected to the inverter board 44 and the magnetic bearing board 45, and a part of the cooling air is supplied to the inverter board 44 and the magnetic bearing board 45 to cool the inverter board and the magnetic bearing board. As a result, it is not necessary to install a fan in the housing.

According to the present embodiment, the air obtained by regenerating the adsorbent of the dryer 22a is guided to the electric motor and the control panel of the compressor 1 and is effectively used as reject air. The consumption can be reduced. In addition, since a cooling fan is not required in the casing of the control panel, it is economical.

[0037]

As described above, according to the present invention, in the compressed air producing apparatus including the compressor and the dryer, the power consumption of the blower and the electric heater of the dryer can be reduced, and the economical efficiency during operation can be improved. Further, since the electric motor is cooled by the air in which the adsorbent of the adsorption type dryer is regenerated, the consumption of the compressed air in the compressor and the dryer can be reduced. Furthermore, each of the above effects can be achieved without employing a particularly complicated configuration.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of one embodiment of a compressed air production device of the present invention.

FIG. 2 is a schematic configuration diagram of another embodiment of the compressed air producing apparatus of the present invention.

FIG. 3 is a schematic configuration diagram of still another embodiment of the compressed air producing apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Electric motor, 3 ... Rotating shaft, 4a, 4b ... Impeller, 5 ... Motor stator, 6a, 6b ... Radial magnetic bearing, 7 ... Axial magnetic bearing, 8 ... Compressor suction air piping, 9 ... compressor discharge air piping, 10 ... dryer discharge air piping, 11a, 11b ... cooler, 12 ... compressor discharge check valve, 13 ... outlet valve, 14 ... control valve, 15 ... check valve, 16 ... outlet passage, 17, 18: motor cooling air pipe, 19: motor cooling air pipe, 20: throttle, 21a,
21b: Cool drain, 22a, 22b: Dryer, 2
3a, 23b: adsorption cylinder, 24a, 24b: switching valve, 25
... Blower, 26 ... 3-way valve, 27 ... Electric heater, 28 ... External supply air pipe, 29 ... Dryer exhaust pipe, 30 ... 3-way valve, 31 ... Air release valve, 32 ... Exhaust, 33a, 33b ...
3-way valve, 34a, 34b ... check valve, 35a, 35b
... fixed throttle, 36 ... cooler, 37 ... electric motor cooling air pipe, 38 ... cool drain, 41a, 41b ... adsorption cylinder, 4
2 ... three-way valve, 43 ... air relief valve, 44 ... inverter board,
45: magnetic bearing control panel, 46: throttle valve, 47: control panel cooling air pipe, 48: control panel cooling air exhaust pipe, 49: motor drive wiring, 50: magnetic bearing wiring.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hideo Nishida 603, Kandamachi, Tsuchiura-shi, Ibaraki Pref. Inside the Tsuchiura Plant, Hitachi, Ltd. Inside the Tsuchiura Plant (72) Inventor Yasuo Fukushima 603, Kandamachi, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant, Hitachi, Ltd. F-term (reference) 3H035 AA02 AA06 CC06 DD05

Claims (8)

[Claims] An air compressor having an electric motor, a centrifugal impeller attached to an end of a rotating shaft of the electric motor, and a dryer for dehumidifying air compressed by the air compressor. In the manufacturing apparatus, a cooling unit that cools the compressed air compressed by the compressor, a first flow path that extracts a part of the compressed air cooled by the cooling unit and guides the extracted portion to the electric motor, A second flow passage for guiding the cooled compressed air to the dryer; 2. The method according to claim 1, wherein the dryer is an adsorption type dryer having a blower, and switches between air introduced from the electric motor and air supplied from the blower when regenerating the adsorbent contained in the dryer. The compressed air producing apparatus according to claim 1, further comprising means. 3. The compressed air producing apparatus according to claim 1, wherein a flow rate adjusting means for adjusting an amount of compressed air guided to the dryer is provided in the first flow path. 4. A dehumidifying method for dehumidifying compressed air compressed by a compressor having a centrifugal impeller attached to a shaft end of an electric motor with a dryer, wherein the air cooled by the electric motor when the compressor is in an on-load operation. Is introduced into the dryer to regenerate the adsorbent, and when the compressor is in the unload operation, the adsorbent is regenerated with air from a blower provided in the dryer. 5. Compressed air provided with an air compressor having an electric motor, a centrifugal impeller attached to an end of a rotating shaft of the electric motor, and a dryer for dehumidifying air compressed by the air compressor. In the manufacturing apparatus, a cooling unit that cools the compressed air compressed by the air compressor, a first pipe that guides the compressed air cooled by the cooling unit to the electric motor or the dryer, and a space between the electric motor and the dryer. And a second pipe through which compressed air for cooling the electric motor or regenerating the adsorbent in the dryer flows. 6. The compressed air production according to claim 5, wherein a three-way valve is provided in the second pipe, and the three-way valve is connected to the first pipe by a third pipe. apparatus. 7. The motor according to claim 5, wherein said electric motor is an electric motor driven by an inverter, and a pipe is provided for guiding compressed air obtained by regenerating an adsorbent in said dryer to a control panel of said inverter. The compressed air producing apparatus according to the above. 8. A pipe according to claim 5, wherein said rotating shaft is supported by a magnetic bearing, and a pipe is provided for guiding compressed air obtained by regenerating an adsorbent in said dryer to a control panel of said magnetic bearing. Compressed air production equipment.