JPH0830475B2 - Operating method of turbo pump for high purity liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for operating a turbo pump for high-purity liquid, in which wear impurities generated in a rotary sliding portion of the turbo pump are In order to prevent the rotary sliding portion from penetrating into the pump chamber through the narrow shaft penetrating portion gap, the flow rate of the pump handling liquid flowing from the pump chamber to the shaft penetrating portion gap is changed to the pressure change of the pump chamber. Regardless of the above, it relates to a method of maintaining a predetermined flow rate.

(Prior Art) In a turbo pump that feeds a high-purity liquid such as a cleaning liquid or an etching liquid in the semiconductor manufacturing process, a rotary sliding part such as a bearing or a mechanical seal or a shaft seal part such as a gland packing is rotated and slid. Wear impurities are generated, and some of the wear impurities are pressure pulsation generated in the narrow shaft penetrating gap between the pump portion and the bearing or between the pump chamber and the shaft seal portion, and the wear impurities are ultrafine particles. Due to the diffusion phenomenon that occurs due to this, it enters the pump chamber through the gap between the shaft penetrating parts and mixes into the pump discharge liquid,
There is a problem that the purity of the pump discharge liquid is lowered.

Therefore, the present applicant has proposed “Operating method of turbo pump for high-purity liquid” (hereinafter referred to as prior invention) of Japanese Patent Application No. 1-64865.

According to the operating method of the invention of the prior application, in a turbo pump in which an impeller arranged in a pump chamber rotates in a non-contact manner, wear impurities generated in a rotary sliding portion of the turbo pump have a narrow shaft penetrating portion from the rotary sliding portion. In order to prevent entry into the pump chamber through a gap, the pump handling liquid having a predetermined flow rate is constantly pumped while the turbo pump is rotating and until a predetermined time elapses after the turbo pump is stopped. Liquid is passed from the chamber to the gap through the shaft.

FIG. 2 shows an example of a high-purity liquid turbopump device employing a canned motor pump for applying the operating method of the invention of the prior application, in which the discharge pump 2 is always operated while the canned motor pump 1 is rotating. Due to the suction force of the lever discharge pump 2 and the discharge pressure of the impeller 24 of the canned motor pump 1, a part of the pump handling liquid in the pump chamber 3 is generated at a predetermined flow rate, that is, by the rotational sliding of the bearings 4 and 5. After the wear impurities can be prevented from entering the pump chamber 3 through the narrow shaft penetrating portion gap 6 and the canned motor portion 7 can be sufficiently cooled, after passing through the shaft penetrating portion gap 6 at a flow rate of a minimum flow rate or more. , Is passed through the canned motor unit 7 and discharged from the discharge pump 2 to the outside of the canned motor pump 1 through the flow meter 8, the electromagnetic switching valve 9 and one of the flow rate control valves 10, After the pump 1 is stopped, the discharge pump 2 is continuously operated until a predetermined time elapses, that is, at least until the wear impurities remaining in the canned motor unit 7 are discharged to the extent that there is no practical problem. The pump handling liquid in the pump chamber 3 is determined by the suction force of the discharge pump 2 or the suction head of the canned motor pump 1 at the pump suction port 12 caused by the suction force of the discharge pump 2 and the liquid level of the suction tank 11. Liquid is passed through the shaft penetrating gap 6 at a flow rate, that is, at a flow rate that is more than a flow rate that can prevent the wear impurities remaining in the canned motor portion 7 from entering the pump chamber 3 through the shaft penetrating gap 6. After that, the discharge pump 2 is passed through the canned motor unit 7.
To flow meter 8, electromagnetic switching valve 9 and other flow rate control valve 13
By discharging to the outside of the canned motor pump 1 via the, the deterioration of the purity of the pump discharge liquid due to the wear impurities is prevented.

(Problems to be Solved by the Invention) By the way, in this high-purity liquid turbo pump device, while the canned motor pump 1 is rotating, the pump discharge port
If the pump discharge flow rate of the canned motor pump 1 is increased or decreased by operating the discharge valve 15 connected to the 14 side or changing the rotation speed of the canned motor pump 1 with an inverter, and after stopping the canned motor pump 1, the suction tank When the pushing liquid head at the pump suction port 12 increases or decreases due to the elevation of the liquid level of 11, the pressure of the pump chamber 3 changes, and the flow rate of the pump handling liquid flowing from the pump chamber 3 to the shaft penetrating portion gap 6 becomes Change.

In order to prevent the wear impurities from entering the pump chamber 3 even when the pressure changes in the pump chamber 3 as described above, when the pressure in the pump chamber 3 becomes the lowest during the rotation of the canned motor pump 1 and after the stop thereof, respectively. A pump handling liquid having a predetermined flow rate is supplied from the pump chamber 3 to the gap 6 between the shaft penetrating portions.
It suffices to adjust the flow rate adjusting valves 10 and 13 so as to allow the liquid to pass through, but the pump discharge flow rate of the canned motor pump 1 is reduced by narrowing the discharge valve 15 or the rotational speed of the canned motor pump 1 is reduced by an inverter. When it is raised and increased, and when the liquid level of the suction tank 11 rises and the pushing liquid head at the pump suction port 12 increases, the pressure in the pump chamber 3 rises and liquid is passed from the pump chamber 3 to the shaft penetrating portion gap 6. Since the flow rate of the pump handling liquid to be used increases, that is, a large amount of expensive high-purity liquid is discharged to the outside of the canned motor pump 1, the excess discharge liquid is discarded or reprocessed. The operating cost is high.

In order to prevent an increase in operating cost due to the unnecessary discharge of the pump handling liquid, as shown in FIG. 3, the electrically operated valve 16 and the flow sensor 17 are sequentially connected to the rear of the discharge pump 2, and the canned motor pump is connected. The signal from the flow rate setters 18 and 19 which set the flow rate of the pump handling liquid flowing from the pump chamber 3 to the shaft penetrating portion gap 6, that is, the discharge flow rate of the discharge pump 2 and the above, respectively, during the rotation of 1 and after the stop and The comparison circuit 20 compares the signal from the flow rate sensor 17 with each other, and the drive circuit 21 compares the signals from the comparison circuit 20 with each other.
By adjusting the opening degree of the electrically operated valve 17 at, the discharge flow rate control device 22 for controlling the discharge flow rate of the discharge pump 2 during the rotation of the canned motor pump 1 and after the stop can be provided. However, since the manufacturing cost of the electrically operated valve 16 and the flow rate sensor 17 is as high as that of the canned motor pump 1 having a relatively small capacity, the overall equipment cost of the turbo pump apparatus for high-purity liquid increases significantly. To do.

In addition, as shown by the broken line arrow in FIG. 2, the expensive pump handling liquid discharged to the outside of the canned motor pump 1 is returned to the pump suction port 12 side through the filter device 23 after passing through the discharge pump 2 and the like. Even in such a case, if the flow rate of the pump handling liquid flowing from the pump chamber 3 into the shaft penetrating portion gap 6 becomes larger than necessary, the discharge pump 2 and the filter device 23 having a large capacity are required, and the equipment cost is increased accordingly. As the cost increases, the volumetric efficiency of the canned motor pump 1 decreases and the operating cost increases.

In this case, if the discharge flow rate control device 22 is provided, an increase in operating cost can be prevented, but even if the discharge pump 2 and the filter device 23 have a small capacity, the electrically operated valve 16 and the flow rate sensor 17 are provided.
Therefore, it is not possible to expect a reduction in equipment cost.

As shown in FIG. 2 and FIG. 3, the canned motor is constructed by directly connecting the canned motor part 7 and the turbo pump part 25 in which the impeller 24 arranged in the pump chamber 3 rotates without contact. In addition to the turbo pump device for high-purity liquid that employs the pump 1, as shown in FIG. 4, the turbo pump unit in which the impeller 24 disposed in the pump chamber 3 rotates without contact
25 and the canned motor unit 7 are connected via the adapter 26, and the liquid in the canned motor unit 7 is circulated between the canned motor unit 7 and the heat exchanger 28 by the auxiliary impeller 27 to cool the canned motor unit 7. By adopting the canned motor pump 1 configured so as to allow the pump handling liquid on the pump discharge side of the pump chamber 3 to flow into the pump rear chamber 30 through the through hole 29 of the adapter 26, a part of the pump rear chamber 30 is introduced. Is returned to the pump chamber 3 through a narrow shaft penetrating gap 31 between the boss portion of the impeller 24 and the adapter 26, and the remaining portion of the rotary shaft 33 between the pump rear chamber 30 and the canned motor front chamber 32.
After passing through the narrow shaft penetrating portion gap 6 between the adapter 26 and the adapter 26 to flow into the canned motor portion 7 and pass through the inside of the canned motor portion 7, or as shown by a dashed arrow, the canned motor front chamber 32 Directly from the canned motor pump 1
Of the high-purity liquid, which is configured to be discharged to the outside of the pump and guided to the discharge pump 2, and a turbo pump unit in which the impeller 24 disposed in the pump chamber 3 rotates without contact as shown in FIG. A magnetic coupling pump 36, which is configured by coupling the 25 and a general-purpose motor 34 through a magnetic coupling 35, is adopted, and the pump handling liquid in the pump chamber 3 is passed through the narrow shaft penetrating portion gap 6 and then the front portion. While lubricating the bearing 37, a part of the bearing 37 is introduced into the front rotor chamber 39 through the rotary sliding portion gap between the bearing 37 and the thrust color 38, and the rest is passed through the through hole 41 of the rotor 40, and then the rear bearing 42. While lubricating the rear bearing 42 and the rear thrust
Through the gap of the rotary sliding portion with 43, the remainder is guided from the rear side chamber 44 of the magnetic coupling to the rear rotor chamber 46 through the through groove 45, and from this rear rotor chamber 46, the gap 48 between the rotor 40 and the partition wall body 47. Through the partition wall body 47 while cooling the partition wall body 47 to the front rotor chamber 39, discharging from the front rotor chamber 39 to the outside of the magnetic coupling pump 36 and guiding to the discharge pump 2. In the pump device as well, and as shown in FIG. 6, the turbo pump unit 25, in which the impeller 24 disposed in the pump chamber 3 rotates in a non-contact manner, and the general-purpose motor 34 are provided with a shaft sealing unit 49 such as a mechanical seal or a gland packing. Motor pump configured by coupling via
50, the pump handling liquid in the pump chamber 3 is passed through the narrow shaft penetrating portion gap 6 and then the shaft sealing portion 49 is passed through the shaft penetrating portion gap 6.
The same problem also occurs in the high-purity liquid turbo pump device configured so as to flow into the pump rear chamber 51 formed between the above and the above, discharge from the pump rear chamber 51 to the outside of the motor pump 50, and lead to the discharge pump 2. there were.

The present invention has been made in view of the above problems, and in the method for operating a high-purity liquid turbopump of the prior invention,
An object of the present invention is to provide an operation method in which the flow rate of the pump handling liquid flowing from the pump chamber to the narrow shaft penetrating portion can be controlled to a constant flow rate, and the equipment cost and the operation cost can be reduced.

[Structure of Invention]

(Means for Solving the Problems) A method of operating a turbo pump for high-purity liquid according to the present invention is a turbo pump in which an impeller arranged in a pump chamber rotates in a non-contact manner, and a rotary sliding portion of the turbo pump is used. To prevent the generated wear impurities from entering the pump chamber through the narrow shaft penetrating portion gap from the rotary sliding portion, always during rotation of the turbo pump, and for a predetermined time after stopping the turbo pump. The discharge pumps consisting of positive displacement rotary pumps having the pump characteristics that the discharge flow rate hardly changes even if the suction pressure changes until After passing the pump handling liquid from the pump chamber into the gap through the shaft penetrating portion, it is discharged to the outside of the turbo pump and guided to the discharge pump.

(Operation) According to the method for operating a high-purity liquid turbo pump of the present invention, while the turbo pump is rotating, the discharge valve connected to the pump discharge port side of the turbo pump is operated, or the turbo pump is operated by an inverter. By changing the rotation speed of the pump to increase or decrease the pump discharge flow rate of the turbo pump, even if the suction pressure of the discharge pump changes due to the pressure change in the pump chamber, and after the turbo pump is stopped, the liquid level in the suction tank Even if the pressure in the pump chamber changes and the suction pressure of the discharge pump changes due to the increase / decrease in the pressure head at the pump suction port of the turbo pump as the suction pump moves up and down, the discharge flow rate is almost the same as the suction pressure changes. Since the discharge pumps composed of positive displacement rotary pumps having pump characteristics that do not change are operated while being maintained at predetermined rotation speeds, respectively, the discharge flow rate of the discharge pumps, That is, the flow rates of the pump handling liquids that are discharged from the pump chamber to the outside of the turbo pump by passing through the narrow gap between the shaft penetrating portions change only negligibly in practical use, and are maintained at a predetermined flow rate. .

(Example) Next, the Example of this invention is described based on drawing.

FIG. 1 shows a high-purity liquid turbopump device adopting a canned motor pump for applying the operating method of the present invention, and the canned member shown in FIG. 3 for applying the operating method of the prior invention. In a high-purity liquid turbopump device employing a motor pump, the electrically operated valve 16 and the flow sensor 17 are removed and the discharge flow control device 22 is removed,
Instead of the conventional discharge pump 2, a discharge pump 52 comprising a positive displacement rotary pump having a pump characteristic such that the discharge flow rate hardly changes even if the suction pressure changes, such as a gear pump, a vane pump, a lobe pump, and a flexible pipe pump. A switching circuit 53 that is used to switch between the rotation and the stop of the canned motor pump 1, that is, the rotation speed setting device 54 that is transmitted through the switched circuit 53 that switches depending on whether power is applied to the canned motor pump 1 or The signal from either one of 55 and the signal from the rotation speed sensor 56 that detects the rotation speed of the discharge pump 52 is compared in the comparison circuit 57, and the signal from this comparison circuit 57 is transmitted via the drive circuit 58. The drive motor 59 of the discharge pump 52 is operated so that the rotation speed of the discharge pump 52 during rotation of the canned motor pump 1 and after stoppage of the canned motor pump 1 respectively. Serial rotational speed setting unit 54 and
A rotation speed control device 60 for controlling the rotation speed set at 55 is provided.

Next, an embodiment of the operating method of the present invention in the turbo pump device for high-purity liquid thus configured will be described.

First, during rotation of the canned motor pump 1, a narrow shaft penetrating gap 6 from the pump chamber 3 due to the suction force of the discharge pump 52 and the discharge pressure of the impeller 24 of the canned motor pump 1.
After passing through the canned motor unit 7 and then discharged to the outside of the canned motor pump 1 and discharged from the discharge pump 52, or discharged from the discharge pump 52 to the pump suction port 12 side through the filter device 23. In order to keep the flow rate of the pump handling liquid at a predetermined flow rate, that is, the discharge flow rate of the discharge pump 52, wear impurities generated by the rotational sliding of the bearings 4 and 5 of the canned motor pump 1 are caused by the gap 6 in the shaft penetrating portion.
The discharge flow rate and the rotation speed of the discharge pump 52, which are obtained in advance, are set so that the flow rate is equal to or higher than the minimum flow rate that can prevent the canned motor portion 7 from being sufficiently cooled while intruding into the pump chamber 3 through A predetermined rotation speed is set in one rotation speed setting device 54 based on the relationship, and the discharge pump 52 is constantly
The operation is performed while maintaining this predetermined rotation speed.

Next, after the canned motor pump 1 is stopped, the shaft penetrates from the pump chamber 3 by the suction force of the discharge pump 52, or by the suction force of the discharge pump 52 and the pushing head at the pump suction port 12 of the canned motor pump 1. After passing through the gap 6 and passing through the canned motor portion 7, it is discharged to the outside of the canned motor pump 1 and discharged from the discharge pump 52, or from the discharge pump 52 to the pump suction port 12 side through the filter device 23. The flow rate of the pumped liquid to be recirculated becomes a predetermined flow rate, that is, the discharge flow rate of the discharge pump 52 is such that the wear impurities remaining in the canned motor section 7 pass through the shaft penetrating portion gap 6 to the pump chamber 3. Similarly, a predetermined rotation speed is set in the other rotation speed setting device 55 so that the flow rate is equal to or higher than the minimum flow rate that can prevent the intrusion, and the discharge pump 52 is set for a predetermined time. Until, that is, until the wear impurities remaining at least canned motor unit 7 is discharged to an extent no practical hindrance, operated and maintained at a predetermined rotational speed.

According to the operating method of this embodiment, while the canned motor pump 1 is rotating, the discharge valve 15 is operated, or the rotation speed of the canned motor pump 1 is changed by the inverter to change the pump discharge flow rate of the canned motor pump 1. By increasing or decreasing, the pressure of the pump chamber 3 changes and the suction pressure of the discharge pump 52 also changes, and after the canned motor pump 1 is stopped, the pump of the canned motor pump 1 is moved up and down by the elevation of the liquid level of the suction tank 11. A pump whose discharge flow rate hardly changes in response to a change in suction pressure, even if the pressure in the pump chamber 3 changes and the suction pressure in the discharge pump 52 changes due to the increase or decrease of the pressure head in the suction port 12. Since the discharge pump 52 composed of a positive displacement rotary pump having characteristics is operated while being maintained at a predetermined rotation speed by the rotation speed control device 60, the discharge pump 52 The discharge flow rate of the pump handling liquid, that is, the flow rate of the pump handling liquid that is discharged from the pump chamber 3 to the outside of the canned motor pump 1 through the narrow shaft penetrating gap 6 is
Even if the pressure in the pump chamber 3 is doubled or halved, it changes only a few percent, which is an extremely small change, and can be ignored in practice.

Therefore, the discharge flow rate of the discharge pump 52 is several percent of the minimum required flow rate of the pump handling liquid flowing from the pump chamber 3 to the shaft penetrating portion gap 6 while the canned motor pump 1 is rotating and after being stopped. By setting the rotation speed of the discharge pump 52 in the rotation speed setters 54 and 55, respectively, based on the relationship between the discharge flow rate and the rotation speed of the discharge pump 52, which has been obtained in advance, so that the second speed is increased. It is possible to prevent an increase in operating cost due to discharging a large amount of expensive high-purity liquid to the outside of the canned motor pump 1 like the conventional high-purity liquid turbo pump device shown in FIGS. And an electrically operated valve which is considerably expensive to configure the discharge flow control device 22 like the conventional turbo pump device for high-purity liquid shown in FIG.
It is possible to prevent an increase in equipment cost due to the provision of 16 and the flow rate sensor 17.

In addition, in the rotation speed setting device 54, 55, in place of the rotation speed scale, or with the rotation speed scale, the discharge flow rate scale is engraved based on the relationship between the discharge flow rate and the rotation speed of the discharge pump 52 that is obtained in advance. By doing so, the complexity of setting the rotation speed setters 54 and 55 by converting the rotation speed into the required discharge flow rate is eliminated.

Further, in the turbo pump device for high-purity liquid shown in FIG. 1, the rotation speed sensor 56, the rotation speed setting devices 54,5
5. A rotation speed control device 60 including a switching circuit 53, a comparison circuit 57 and a drive circuit 58 is provided, but a synchronous motor whose rotation speed is proportional to the power supply frequency regardless of load changes is adopted as the drive motor 59 of the discharge pump 52. In addition, a frequency variable power supply device for driving this synchronous motor is provided, and the discharge pump 52 is operated at a predetermined rotation speed by operating the discharge pump 52 at a rotation speed proportional to the power supply frequency set by the frequency variable power supply device. It is only necessary that the vehicle can be operated at the speed maintained.

As described above, according to the operating method of the present invention, the canned motor pump 1 configured by directly connecting the turbo pump unit 25 and the canned motor unit 7 in which the impeller 4 disposed in the pump chamber 3 rotates in a non-contact manner is used to achieve high purity. Although the embodiment applied to the liquid turbo pump device has been described, as shown in FIG. 4, the canned motor pump 1 configured by connecting the turbo pump unit 25 and the canned motor unit 7 via the adapter 26. Alternatively, as shown in FIG.
A magnetic coupling pump 36 configured by coupling 25 and a general-purpose motor 34 via a magnetic coupling 35,
Alternatively, as shown in FIG. 6, the turbo pump unit 25
The same can be applied to a high-purity liquid turbo pump device that employs a motor pump 50 configured by coupling a general-purpose motor 34 and a general-purpose motor 34 via a shaft seal portion 49 such as a mechanical seal or a gland packing.

〔The invention's effect〕

According to the method for operating a high-purity liquid turbopump of the present invention, the wear impurities generated in the rotary sliding portion of the turbo pump in which the impeller 24 arranged in the pump chamber 3 rotates in a non-contact manner are the rotary sliding portions. In order to prevent the gas from penetrating into the pump chamber 3 through the narrow shaft penetrating portion gap 6, the pump is handled at a predetermined flow rate at all times during the rotation of the turbo pump and until a predetermined time elapses while the turbo pump is stopped. Liquid pump chamber 3
In the operating method in which liquid is passed through the shaft penetrating portion gap 6 from the nozzle to the outside of the turbo pump through the discharge pump 52, the discharge flow rate hardly changes even if the suction pressure of the discharge pump 52 changes. By adopting a positive displacement rotary pump having pump characteristics and operating the discharge pump 52 while maintaining the respective predetermined rotation speeds, the pressure in the pump chamber 3 is changed during and after the turbo pump is stopped and discharged. Even if the suction pressure of the pump 52 changes, the discharge flow rate of the discharge pump 52, that is, the gap 6 from the pump chamber 3 to the shaft penetrating portion.
Since the flow rates of the pump handling liquids discharged to the outside of the turbo pump after passing through the tanks change very little to practically negligible levels and are maintained at a predetermined flow rate, the conventional flow rate shown in FIG. A large amount of expensive high-purity liquid is needed outside the turbo pump without providing the discharge flow rate control device 22 that requires the electrically operated valve 16 and the flow rate sensor 17 which are quite expensive like the turbo pump device for high-purity liquid of It does not need to be discharged to, and the equipment and operating costs are low.

[Brief description of drawings]

FIG. 1 is a cross-sectional view including a circuit diagram of a high-purity liquid turbopump device adopting a canned motor pump for applying an operating method of an embodiment of the present invention, and FIG. 2 is a conventional adopted canned motor pump. FIG. 3 is a sectional view of a turbo pump device for high-purity liquid of FIG. 3, FIG. 3 is a sectional view including a circuit diagram of another conventional turbo pump device for high-purity liquid, FIG. 4, FIG. It is sectional drawing of the conventional high purity liquid turbopump apparatus which adopted the other canned motor pump, the magnet coupling pump, and the motor pump of a general purpose motor drive which has a shaft sealing part. 1 ... Canned motor pump, 3 ... Pump chamber, 4,5 ...
... Bearing, 6 ... Gap through shaft, 7 ... Canned motor, 11 ... Suction tank, 12 ... Pump suction port, 14 ...
… Pump discharge port, 15… Discharge valve, 23… Filter device,
24 …… impeller, 25 …… turbo pump part, 26 …… adapter, 27 …… auxiliary impeller, 28 …… heat exchanger, 24 …… general-purpose motor, 35 …… magnet coupling, 36 …… magnet coupling pump , 37 …… front bearing, 42…
… Rear bearing, 49 …… Shaft seal part, 50 …… Motor pump, 51 …… Pump rear chamber, 52 …… Discharge pump, 53 …… Switching circuit, 54, 55 …… Rotation speed setting device, 56 …… Rotation Speed sensor, 57 …… Comparison circuit, 58 …… Drive circuit, 59 …… Drive motor, 60 …… Rotary speed controller.

Claims (1)

[Claims] 1. In a turbo pump in which an impeller arranged in a pump chamber rotates in a non-contact manner, wear impurities generated in a rotary sliding portion of the turbo pump pass through the narrow shaft penetrating portion gap from the rotary sliding portion. In order to prevent the turbo pump from entering the pump chamber, the discharge flow rate is almost constant during the rotation of the turbo pump until the predetermined time elapses after the turbo pump is stopped even if the suction pressure changes. By operating the discharge pumps composed of positive displacement rotary pumps having the same pump characteristics at the predetermined rotation speeds, the pump handling liquids at the respective predetermined flow rates were made to flow from the pump chambers to the shaft penetrating portion gaps. After that, the turbo pump for high-purity liquid is discharged to the outside of the turbo pump and guided to the discharge pump.