JP3528057B2 - Degassing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deaerator for removing air and other gases contained in liquid.

[0002]

2. Description of the Related Art Conventionally, as a deaerator used to remove air and other gases contained in liquid, a vacuum pump is connected to a vacuum chamber (deaeration chamber) having a permeable membrane tube inside. There is known a degassing device (for example, Japanese Patent Laid-Open No. 4-203479).

The liquid from which the gas is to be removed is circulated in the permeable membrane tube, and the air and other gases contained in the liquid are passed through the tube wall to the vacuum chamber side for removal. Based on the output signal of a pressure sensor provided in the vacuum chamber, the start and stop of the vacuum pump are controlled via a control circuit so that a predetermined pressure of several tens Torr is maintained in the vacuum chamber. .

The permeable membrane tubes are installed in the vacuum chamber in 1 to 6 systems. In a liquid chromatography device using this type of degassing device, when performing analysis by a gradient method, degassing of several types of liquids, such as multiple carrier liquids such as water, methyl alcohol, tetrahydrofuran, acetonitrile, etc., can be performed in parallel. It is possible to deal with the need to do so.

[0005]

In the above deaerator, when the liquid to be degassed is an organic solvent such as tetrahydrofuran, ethyl acetate, methanol, ethanol, hexane, etc., the liquid to be degassed permeates through the permeable membrane. Therefore, there is a problem in that the organic solvent leaches out to the deaeration chamber side, and the leached organic solvent damages the vacuum pump and other exhaust systems connected to the deaeration chamber.

When the organic solvent leaches into the deaeration chamber side, the organic solvent repeats only the phase change between the gas phase and the liquid phase in the vacuum pump, and the external discharge by the vacuum pump is not executed. In such a situation, the organic solvent causes corrosion of the metal parts that make up the vacuum pump and swelling of synthetic rubber O-rings and other sealing parts, which causes the exhaustion of the vacuum pump due to inoperability and loss of valve function. It caused a failure such as inability. The compounding of several solvents can also lead to unexpected failures.

It is unavoidable for the purpose of use of the vacuum pump that such condensation of the exhaust gas occurs in the vacuum pump. That is, the gas exhausted via the vacuum pump must be finally exhausted under atmospheric pressure,
Therefore, the exhaust gas needs to be compressed in the vacuum pump to a pressure higher than atmospheric pressure. As a result, the dew point of the exhaust gas is lowered, and condensation occurs. Therefore, there has been a conventional method in which air is introduced into the vacuum chamber regularly or intermittently to forcibly exhaust the condensate in the vacuum chamber and the vacuum pump together with the air.
Since damage to the equipment or parts by condensate is unavoidable, it cannot be said to be a fundamental solution.

The present invention fundamentally solves the problems as described above, and provides a deaerator capable of continuing operation without damaging the exhaust system even when deaerating an organic solvent. The purpose is to do.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention constantly introduces a predetermined amount of atmosphere into the exhaust gas and / or heats the exhaust gas so that condensation of the exhaust gas does not occur. It was done.

That is, the present invention relates to a degassing device comprising a vacuum chamber accommodating a permeable membrane tube and an exhaust vacuum pump connected to the vacuum chamber, wherein the vacuum pump is a cascade pump or a diaphragm pump.
The exhaust gas in the suction chamber for the exhaust gas of the pump.
A degassing device, characterized in that the air introducing portion for limiting to less conductance than the conductance of the intake communication passage is provided.

Still another invention is a deaerator comprising a vacuum chamber accommodating a permeable membrane tube and an exhaust vacuum pump connected to the vacuum chamber, wherein the vacuum pump is a cascade pump or a diaphragm pump.
And a heating means is provided in the exhaust gas suction chamber of the pump .

Next, another invention is a deaeration apparatus comprising a vacuum chamber accommodating a permeable membrane tube and an exhaust vacuum pump connected to the vacuum chamber, wherein the vacuum pump is a cascade pump or a diaphragm type. Pong
The exhaust gas in the suction chamber for the exhaust gas of the pump.
With ambient air intake part focused on smaller conductance than the conductance of the suction communication passage is provided in a degassing device, characterized in that the heating means is provided.

Further , the vacuum pump may have one or a plurality of serial connection configurations.

Further, the atmosphere introducing portion can be constituted by a pipe, a capillary or an orifice provided with a needle valve.

[0015]

According to the degassing apparatus of the present invention, the degassed gas and the atmosphere in the vacuum chamber are simultaneously sucked into the suction chamber of the vacuum pump, and / or the gas sucked into the suction chamber is heated. The partial pressure of the condensable gas contained in the sucked gas is lowered, and / or the temperature is higher than the dew point, and the gas can be exhausted to the outside without causing condensation.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a deaerator according to the first embodiment of the present invention, which comprises a vacuum chamber 1 and a vacuum pump 2. The vacuum chamber 1 accommodates therein a permeable membrane tube 3 (a single system is shown in the drawing, but a plurality of systems may be used), and a liquid to be degassed can be circulated in the permeable membrane tube 3. ing.

The vacuum pump 2 is a cascade type pump in which bottomed cylindrical pump casings 4 and 5 are provided with their openings facing each other, and a piston 6 reciprocates between the pump casings 4 and 5. It is possible. The reciprocating movement of the piston 6 is performed by the eccentric cam 7 engaged with the piston 6.
Is performed by rotating the motor 8. The control circuit 9 of the motor 8 receives the signal from the pressure sensor 10 attached to the vacuum chamber 1 to control the ON / OFF of the motor 8. Reference numeral 11 in the figure denotes an O-ring mounted on the piston 6, and is designed to maintain airtightness with the inner wall surfaces of the pump casings 4 and 5. Further, 12 is a conduit connecting between the vacuum chamber 1 and the pump casing 4, 13 is a conduit connecting between the pump casing 4 and the pump casing 5, and 14 is an exhaust pipe connected to the pump casing 5. A check valve 15 is provided in each of the conduits 12 and 13 and the exhaust pipe 14, and the flow direction of gas is regulated as shown by an arrow 16. The conduit 13 is the piston 6
It is also possible to have a structure in which a through passage is formed in the inside of the container along the longitudinal direction and a check valve is installed therein.

One end of another conduit 17 is connected to the pump casing 5 of the latter stage (high pressure side) of the pump casings 4 and 5, and the needle valve 18 is connected to the conduit 17.
Is installed. The conduit 17 and the needle valve 18 constitute an atmosphere introducing portion 19 for the pump casing 5, and the conductance of this atmosphere introducing portion 19 is
It is adjusted to be smaller than the conductance of the suction passage 20 of the pump casing 5, which is composed of the conduit 13 and the check valve 15.

For example, if the conductance of the atmosphere introducing portion 19 is adjusted to be approximately equal to the conductance of the suction passage 20, the gas sucked into the pump casing 5 is approximately one-to-one with the gas exhausted from the vacuum chamber 1 side and the atmosphere.
And the partial pressure of the gas (particularly the condensable gas) contained in the exhausted gas can be reduced to about 1/2. Therefore, the opening degree of the needle valve 18 is adjusted and the conductance is set in consideration of the components and properties of the gas to be actually exhausted.

In the deaerator of the above embodiment, the liquid to be degassed is passed through the permeable membrane tube 3 and the vacuum pump 2 is used.
In the operating state, the gas contained in the liquid to be degassed can be transmitted to the vacuum chamber 1 side and removed by the vacuum pump 2.

The pressure inside the vacuum chamber 1 is measured by the pressure sensor 1.
The vacuum pump 2 is ON / OFF controlled by the control circuit 9 so as to be detected at 0 and maintained at a predetermined pressure. An example of the pressure of each part is about 45 To in the vacuum chamber 1.
rr (6000 Pa), 20 to 2 in the pump casing 4
00 Torr (2600-26000 Pa), 70-760 Torr (9000-101000) in the pump casing 5.
Pa).

In the degassing action as described above, some liquid to be degassed permeates through the permeable membrane tube 3 and is mixed in the exhaust gas. When the liquid to be degassed is an organic solvent such as tetrahydrofuran, ethyl acetate, methanol, ethanol, hexane, etc., these permeated liquids cause condensation in the pump casing 5, and the O-ring 11 and the pump casing 5 ( (If it is made of metal), the seal parts and the like of the check valve 15 are damaged. This is because the exhaust gas in the pump casing 5 is pressurized to a pressure higher than the atmospheric pressure and is discharged to the atmosphere side through the check valve 15.

However, in the deaerator of the embodiment, as described above, the atmosphere is introduced into the pump casing 5 through the atmosphere introducing portion 19 to reduce the partial pressure of the condensable exhaust gas, so that the non-return Even in the step of releasing under pressure through the valve 15, the discharge is performed without causing condensation. As a result, damage to the O-ring 11 and other members can be prevented.

FIG. 2 is a block diagram of the deaerator of the second embodiment of the present invention. A heater 21 is provided as a heating means for the pump casing 5 in place of the air introduction section of the above embodiment. The heater 21 is the heater controller 2
The heater controller 22 controls the heater 21 on the basis of the pressure change rate of the vacuum chamber 1 provided from the control circuit 9 to control the pump casing 5
Can be heated to a predetermined temperature (for example, 25 to 50 ° C.). The other parts have the same structure as the above-mentioned embodiment, and therefore, the same members are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, when the condensable gas is guided to the pump casing 5 side, the gas is heated through the heater 21 and can be heated to a temperature sufficiently higher than the dew point, so that the check valve 15 does not condense. Can be discharged to the outside through.

When condensation occurs in the pump casing 5, the condensable gas is repeatedly condensed and vaporized in the pump casing 5 as the piston 6 reciprocates, and the condensable gas undergoes a phase change between a liquid phase and a gas phase to be exhausted. Disappear. In this case, the gas transfer from the pump casing 4 to the pump casing 5 is not performed either, so that the function of the vacuum pump 2 is deteriorated and the reduction of the pressure of the vacuum chamber 1 does not occur. In such a situation, the pressure sensor 10 and the control circuit 9
Since it is transmitted to the heater controller 22 through the heater 21 and the heating is enhanced by the heater 21, the pump function is prevented from deteriorating and the exhaust gas is discharged to the outside without being condensed, so that the pump casing 5, the O-ring 11, the check valve. It is possible to prevent damage such as 15.

Next, FIG. 3 is a block diagram of the deaerator of the third embodiment of the present invention. Both the atmosphere introducing portion 19 of the first and second embodiments and the heater 21 as a heating means are provided. Therefore, the same members as those in the above-described respective embodiments are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the atmosphere is introduced into the pump casing 5 at a predetermined ratio, the partial pressure of the condensable gas is lowered, and the gas is heated by the heater 21 to be a gas having a temperature sufficiently higher than the dew point. It is possible to prevent condensation and prevent damage to the O-ring 11 and the like.

FIG. 4 shows another embodiment of the atmosphere introducing section 19. FIG. 4A shows the case where the atmosphere introducing section 19 is constructed by connecting the capillary 23 to the pump casing 5.
FIG. 7B shows a case where the orifice 24 is formed on the side wall of the pump casing 5 to form the atmosphere introducing portion 19. In either case, when the conductance of the atmosphere introducing unit 19 is constant, the length of the capillary 23 and the diameter of the orifice 24 can be set and implemented.

5 and 6 show an embodiment in which a diaphragm type pump is used instead of the cascade type pump of the above embodiment, and FIG. 5 is a diaphragm type vacuum pump 25,
An example in which two 26 are connected in series, and FIG. 6 is an example in which one diaphragm-type pump is connected. In the figure, 27 is a diaphragm, 28 is a diaphragm drive device (vibration source), and 29 is a control circuit that receives the signal from the pressure sensor 10 and controls the vacuum pumps 25 and 26.

The suction chambers 25a, 26 of the vacuum pump 26 in the latter stage of the embodiment of FIG. 5 and the vacuum pump 25 of the embodiment of FIG.
At a, an end of a conduit 29 provided with a needle valve 18 is connected, and an atmosphere introducing section 30 is provided. The conductance of the atmosphere introducing portion 30 is smaller than the conductance on the suction side. With respect to other members, the members having the same functions as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

Even in the deaerator using the diaphragm type vacuum pumps 25 and 26 as described above, the atmosphere introducing section 3
Since the partial pressure of the condensable gas decreases in the suction chambers 25a and 26a where 0 is provided, condensation is avoided even when exhausting under atmospheric pressure through the exhaust pipe 14, and the diaphragm, the check valve 15, etc. Can be prevented from being damaged.

Since it is possible to provide a heating means by a heater to the diaphragm type vacuum pumps 25 and 26 to heat the suction gas to a temperature higher than the dew point to prevent condensation, the atmosphere introduction section 28 as described above. Instead of or in addition to this, a heating means may be provided to configure the degassing device.

[0035]

As described above, according to the present invention, the condensable gas that has permeated the permeable membrane tube can be discharged without causing condensation, so that damage to the O-ring and other pump components and valve components is prevented. In addition to the effect of being able to be prevented, the exhaust function is not impaired, so that there is an effect of being able to provide a deaerator having excellent deaerating performance.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a view of another embodiment of the atmosphere introducing portion, in which (a) is a capillary and (b) is an enlarged cross-sectional view of an embodiment using an orifice.

FIG. 5 is a configuration diagram of an embodiment using a diaphragm type vacuum pump (two stages).

FIG. 6 is a configuration diagram of an embodiment using a diaphragm type vacuum pump (1 stage).

[Explanation of symbols]

1 vacuum chamber 2 vacuum pump 3 permeable membrane tube 4, 5 pump casing 6 pistons 7 Eccentric cam 8 motor 9 Control circuit 10 Pressure sensor 11 O-ring 12, 13 conduit 14 Exhaust pipe 15 Check tube 16 arrow 17 conduits 18 Needle valve 19 Atmosphere Introduction Department 20 Inhalation passage 21 heater 22 Heater controller 23 capillaries 24 orifice 25, 26 vacuum pump 27 diaphragm 28 Drive 29 conduits 30 Atmosphere Introduction Department

Claims (5)

(57) [Claims] 1. A degassing device comprising a vacuum chamber containing a permeable membrane tube and an exhaust vacuum pump connected to the vacuum chamber, wherein the vacuum pump is a cascade pump or a diaphragm pump. The
A degassing device, wherein an exhaust gas suction chamber of a vacuum pump is provided with an atmosphere introduction section whose conductance is smaller than that of an exhaust gas suction passage. 2. A degassing apparatus comprising a vacuum chamber containing a permeable membrane tube and an exhaust vacuum pump connected to the vacuum chamber, wherein the vacuum pump is a cascade pump or a diaphragm pump. The
A deaerator, wherein a heating means is provided in an exhaust gas suction chamber of the vacuum pump. 3. A degassing apparatus comprising a vacuum chamber containing a permeable membrane tube and an exhaust vacuum pump connected to the vacuum chamber, wherein the vacuum pump is a cascade pump or a diaphragm pump. The
A degassing device, characterized in that an exhaust gas suction chamber of a vacuum pump is provided with an atmosphere introducing section whose conductance is smaller than the conductance of an exhaust gas suction passage and a heating means. 4. A vacuum pump 1 or more serially connected configuration and the deaerator of any one of claims 1 to 3. 5. A needle valve is installed in the air introduction section.
One end is in contact with the exhaust gas suction chamber of the vacuum pump.
A continuous conduit, a suction chamber for the exhaust gas of the vacuum pump
Capillary connected to and adjustable in length, or
Formed on the side wall of the exhaust gas suction chamber of the vacuum pump
With an orifice that can adjust the size of the diameter by
The degassing device according to claim 1 or 3, wherein