JP2004068812A - Superpure water pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent inconvenience of ion generation, etc. of metal, etc. by contact of a main delivered liquid such as superpure water, etc. by discharging abrasive fine particulates on a sliding part of a pump and effectively avoiding intrusion of the main delivered liquid extremely high in chemical activation and having corrosiveness to the sliding part. <P>SOLUTION: A point to contact the main delivered liquid is processed for corrosion resistance, a first blocking current mechanism to prevent contamination of an abrasive article in the sliding part and a second blocking current mechanism to avoid intrusion of the main delivered liquid high in chemical reaction to a point not processed for corrosion resistance are furnished, the first blocking current mechanism is furnished with a first blocking current channel by a rotation axis and an inner peripheral surface of a rotation axis casing and a discharge part to discharge a first blocking current by the main delivered liquid from a pump space from the first channel, and the second mechanism is furnished with an inactive liquid supply source as the second blocking current and a second blocking current supply port formed in the casing to deliver the second blocking current to the inside of the casing and to join it with the first blocking current through the second channel by the rotation axis and the inner peripheral surface of the casing. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotary pump for transferring an extremely high-purity active liquid used in a manufacturing process of a semiconductor, a liquid crystal, and the like, and more particularly, to an insulation between an active liquid such as ultrapure water and a metal part of a pump mechanism. The present invention relates to a pump capable of preventing the generation of other fine particles including metal ions.
[0002]
BACKGROUND OF THE INVENTION
In order to achieve a high degree of integration of a semiconductor, it is necessary to extremely reduce the purity of various liquids used in manufacturing, particularly the content of impurities. In ultrapure water used in the cleaning process of semiconductor manufacturing, the amount of fine particles on the order of 0.1 micron is considered to be a problem and greatly affects the product yield. In particular, in the pump for transferring ultrapure water, it was a major problem to prevent the generation of wear fine particles generated from the rotary sliding portion. This problem was solved by the inventor of the present invention in Japanese Patent No. 1807169 and US Pat. No. 5,131,806 or JP-A-3-26897.
[0003]
However, as the degree of integration of semiconductors and the performance of liquid crystal have been further improved, the concentration of residual metal ions in ultrapure water has become a serious problem, and the content of metal ions has now risen to 1 PPT (parts per trillion). ) The following are required. This metal ion is manifested by the dissolving behavior of ultrapure water in the metal at the liquid contact points of all devices such as pumps, pipes, valves, etc. during the wet process, and in particular, has a maximum resistance value of 18.20 MΩ or more. It is said that in ultrapure water, very active ion elution of metals and the like occurs.
[0004]
[Problems to be solved by the invention]
In order to solve the above-mentioned inconveniences, in a device such as a pump, a cylinder place in contact with ultrapure water is lined with tetrafluoride resin, and coating is also performed. Surface treatment such as lining with a tetrafluoride resin cannot be performed on the seal portion. Further, even when extremely hard SiC (silicon carbide), which is extremely chemically stable, is used for the pump rotary sliding portion and the seal portion, the dissolution behavior by ultrapure water cannot be suppressed. In addition, functional ultrapure water containing a small amount of ozone (O ₃ ), hydrogen fluoride (HF), etc. is being used in the current ultrapure water, and metals and ceramics are exposed to a larger chemical attack. In other words, inconveniences such as corrosion due to elution of the metal ceramics and the like in the liquid contacting parts in the above-mentioned pump rotating sliding parts, that is, the bearing parts and the seal parts, are to be regarded as further problems.
[0005]
[Means for Solving the Problems]
The present invention relates to a pump used for transferring ultrapure water and the like, which includes a pump space, an impeller rotating in the pump space, a rotating shaft connecting a rotary drive source and the impeller, and a rotating portion having a bearing portion and a seal portion. A portion having a shaft casing and being in contact with the main liquid is subjected to anti-corrosion treatment by lining of tetrafluoride resin or the like, and is rotated from a rotary sliding portion such as a bearing portion and a seal portion in contact with the second cutoff flow. A first cut-off flow mechanism for preventing the generated fine particles from being mixed into the liquid feed, and a first cut-off flow mechanism for preventing entry of the main liquid feed from the pump space into a portion where the anti-corrosion treatment is impossible in the rotating shaft sliding portion. Equipped with two cut-off flow mechanisms,
The first cut-off flow mechanism includes a first cut-off flow passage formed by a rotary shaft and an inner peripheral surface of a rotary shaft casing, and a first cut-off by a main liquid supplied partially into the rotary shaft casing from a pump space. In order to discharge the flow from the first cut-off flow channel, the rotary shaft casing includes a discharge portion provided near the impeller, and a discharge passage connected thereto.
The second cutoff flow mechanism is configured to supply a supply source of an inert liquid having lubricity as a second cutoff flow, and to send the second cutoff flow into a rotary shaft casing in which a bearing unit and a seal unit are located, and rotate the rotary shaft. To join the first cut-off flow through the second cut-off flow passage formed by the inner periphery of the rotary shaft casing and discharge from the discharge passage of the first cut-off flow mechanism, the rotary shaft side of the rotary shaft A second cutoff flow supply port formed in the rotary shaft casing between the end and the discharge path, and a supply path provided between the second cutoff flow supply source and the second cutoff flow supply port. This aims to solve the conventional problem.
[0006]
In the pump, the discharge part of the first cut-off flow mechanism is provided with a cut-off disk provided at a meeting point of flows in directions opposite to each other on a rotary shaft of the pump, and a disk chamber provided on a rotary shaft casing for storing the same. It is constituted by opening.
[0007]
In the above, a labyrinth may be formed on the flow path blocking disk to prevent the first and second blocking flows from flowing into the respective flow paths.
[0008]
In any one of the above, a portion where the anti-corrosion treatment cannot be performed in the rotary shaft casing is always filled with a second cut-off flow made of an inert liquid flowing from a second cut-off flow supply port, and enters through the first cut-off flow passage. It is insulated from the main liquid feed, which has a strong chemical attack property, which is likely to occur.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the pump according to this embodiment, the surface of the portion in contact with the main liquid feed (ultra pure water) is lined with a tetrafluoride resin, as described above, except for the rotary sliding portions such as the bearing portion and the seal portion of the rotary shaft casing. And so on. In the first cut-off flow mechanism, the first cut-off flow due to the main liquid supply (ultra pure water) partially flowing into the rotary shaft casing from the pump space is formed by the rotary shaft and the inner periphery of the rotary shaft casing. The discharge water flows out of the rotary shaft casing through one cut-off flow path, a discharge portion provided in the rotary shaft casing near the impeller, and a discharge path connected to the discharge portion. Therefore, the wear fine particles generated from the rotary sliding portions such as the bearing portion and the seal portion are contained in the second cutoff flow, but are blocked by the first cutoff flow and enter the pump shaft direction in the rotary shaft casing. I will not.
[0010]
That is, in the second cut-off flow mechanism, a normal inert liquid (such as tap water) that lubricates ultrapure water as the second cut-off flow is sent from the supply source into the rotary shaft casing and is rotated. Flows through the second cut-off flow passage constituted by the inner peripheral surface of the rotary shaft casing to the discharge portion of the first cut-off flow device, so that the first cut-off flow flows in the direction of a rotating sliding portion such as a bearing portion or a seal portion. Is blocked. Further, the inert liquid (water) as the second cutoff flow sent into the rotary shaft casing is in the rotary shaft casing in a direction opposite to the rotary shaft with respect to the first cutoff flow mechanism, that is, a bearing portion, a seal portion, and the like. In the direction of the rotary sliding portion. Since the end portion of the rotating shaft casing, that is, the tip in the direction of the rotating sliding portion, is closed by a sealing mechanism, the inert liquid (water) contains the rotating sliding portion such as a bearing portion and a sealing portion inside the rotating shaft casing. To isolate the first cutoff flow (ultra pure water) from the rotary sliding part.
[0011]
The pressure and the amount of water at the second cutoff flow supply port of the inert second cutoff flow are higher than that of the first cutoff flow, but the amount of water may be always smaller than that of the first cutoff flow. It is the extent to have. After flowing into the rotary shaft casing, the pressure is gradually reduced so as to become the same pressure since it is extremely smaller than the first cutoff flow rate, and becomes the same pressure at the time of merging and discharging with the first cutoff flow. It does not flow to the side of the pump.
[0012]
The inert liquid (water) that forms the second cutoff flow is supplied by a fixed amount pump including an air pressure, a water pressure, a diaphragm driven by electric power, an air cylinder driven plunger pump, and the like. Available. If necessary, a pressure regulating valve, a flow regulating valve, an on-off valve and the like may be provided in a supply path connecting the supply source and the rotary casing.
[0013]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a main part of a rotary pump according to the present invention. FIG. 2 shows the present invention in which the bearing B is omitted, and the positions of the fixed ring and the rotating ring of the mechanical seal portion are reversed, but the numbering is the same as in FIG.
In the drawing, 1 is a pump space, 2 is an impeller that rotates in the pump space 1, 3 is a rotating shaft connecting the rotary drive source M and the impeller 2, 4 is a fixed ring with a bearing portion B and a mechanical seal portion S, S1 is a rotating shaft casing having a rotating ring S2. Except for the bearing portion B and the seal portion S, each of the elements has been subjected to anticorrosion treatment by lining or the like of tetrafluoride resin at a portion in contact with ultrapure water as a main liquid, and is indicated by a thick solid line. .
[0014]
Reference numeral 5a denotes a disk chamber formed on the inner peripheral surface of the rotary shaft casing 4 between the end in the direction of the impeller 2 and the bearing portion B. The disk chamber 5a is rotatable with a blocking disk 5b provided on the rotary shaft. It is stored in. The discharge section 5 of the first cut-off flow mechanism is formed at a location corresponding to the outer peripheral portion of the disk 5b made of the fluorocarbon resin in the disk chamber 5a. 5c is a discharge passage connected to the disk chamber 5a and a flow control mechanism 5e. 5f is provided. A labyrinth 5d may be formed in the disk chamber 5a.
A first cut-off flow path 6, which is formed by a gap between the rotary shaft 3 and the inner peripheral surface of the rotary shaft casing 4 between the pump empty space 1 and the disk chamber 5a, a discharge section 5, and a discharge path 5c. These form a first cut-off flow mechanism. From the pump space 1, the branch flow of the ultrapure water as the main liquid flows as the first cutoff flow through the first cutoff flow passage 6, the discharge unit 5, and the discharge passage 5 c, so that the bearing unit B and the seal unit S The liquid containing the wear fine particles from entering the pump space 1 from the direction is prevented.
[0015]
In the drawing, T is a supply source of an inert liquid (water), p is a metering pump, 7 is a second cut-off flow supply port formed at an intermediate portion between the bearing portion B and the seal portion S of the rotary shaft casing 4. , 8 are second cutoff flow passages formed by a gap between the rotary shaft 3 and the inner peripheral surface of the rotary shaft casing 4 between the bearing portion B and the disk chamber 5a. It is configured. The position of the second cut-off flow mechanism, specifically, the setting position of the second cut-off flow supply port in the rotary shaft casing 4 is such that, assuming that the pump idle side is the head (the rotary shaft casing 4), Must be behind the blocking plate at the end. Thus, the inert liquid (water) from the supply source flows as the second cut-off flow through the bearing section B, the second cut-off flow path 8, the discharge section 5, and the discharge path 5c, thereby forming the first cut-off flow. The first cutoff flow (ultra pure water) from the discharge section 5 direction of the mechanism is prevented from entering the bearing section B.
[0016]
As described above, the second cut-off flow merges with the first cut-off flow at the discharge portion 5 of the first cut-off flow mechanism and flows out from the discharge passage 5c. If a labyrinth is provided on the disk 5b, it is difficult for the two cutoff flows to mix, and the centrifugal flow generated by the rotation of the 5b will flow out to the discharge path 5c. This further contributes to preventing the first cutoff flow from entering the bearing space B.
[0017]
The inert liquid serving as the second cutoff flow may be ordinary tap water, and is supplied to the second cutoff flow passage 8 at a higher pressure and a smaller amount than the first cutoff flow by a metering pump. As described above, since the second cutoff flow has a high pressure and a small amount, the second cutoff flow has the same pressure as the first cutoff flow in the discharge section 5 and is discharged out of the system via a flow control valve provided in the discharge path 5c. Note that the composition ratio of the merged first cutoff flow and second cutoff flow may be about 1.5: 1 to 50: 1, 100: 1 depending on the case, and the flow direction is determined by the main flow first cutoff flow. You. In summary, the present invention is implemented by securing a larger discharge amount than the second cutoff flow supplied into the system.
[0018]
When the pump stop time becomes longer, metal ions are generated in the ultrapure water during liquid sending from fine abrasion particles generated from the metal ceramics in the liquid contact part. Therefore, in order to obtain ultrapure ultrapure water quality, which requires a concentration of metal ions or the like equal to or less than PPT, immediately after the start of the pump, a large amount of ultrapure water must be pumped through the contaminated pump system at the time of startup. Cleaning with pure water is required. However, this flushing causes an excessive increase in operating cost.
Therefore, in this embodiment, immediately after the operation of the pump is stopped, the operation of the second cutoff flow mechanism is stopped, and the second cutoff flow including wear fine particles such as metal and ceramic is stopped, while the main pump is restarted. By circulating the first cut-off flow in an amount of about 10/1 or less during normal operation, the prevention of ions eluted from metals and ceramics from entering the pump space is further ensured. Since the second cut-off flow mechanism is full of the second cut-off flow mechanism, there is no danger that the first cut-off flow will enter the bearing portion B direction. Or may be operated intermittently. In some cases, a lip seal LS as a check valve may be provided in each of the first and second shutoff channels.
[0019]
In short, in order to prevent ions such as metals generated when the pump is stopped from diffusing throughout the pump system due to Brownian motion, a small amount of cut-off flow is intermittently or continuously circulated to increase the high pressure inside the system. The purpose is to maintain a pure environment.
[0020]
【The invention's effect】
With the above-described configuration and operation, the present invention effectively and efficiently removes the abrasion fine particles generated in the sliding portion of the rotary pump at low cost and effectively prevents the main liquid from entering the sliding portion. In addition, there is an effect that inconvenience such as generation of ions of metal or the like due to contact of the main liquid such as ultrapure water with the sliding portion of the pump can be prevented.
The above description has been made on the exterior (outside type) mechanical seal in which the fixed ring in the mechanical seal is located in the pump chamber and the rotating ring and the spring are located outside the pump chamber. The spring is also used for an internal (inside) type mechanical seal mechanism in the pump chamber, but it is almost the same, so that the illustration is omitted.
Further, the present invention can be effectively used as it is in a gland, packing type, or lip seal type, which is a rotary sliding part sealing method other than the mechanical seal, according to the embodiment shown in the drawings.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of the present application. FIG. 2 is a cross-sectional view of a mechanism in FIG. 1 from which a bearing portion is omitted.

Claims (5)

It has a pump space, an impeller that rotates in the space of the pump, a rotary shaft that connects the rotary drive source and the impeller, and a rotary shaft casing that has a bearing portion and a seal portion. A first cut-off flow mechanism for preventing a second cut-off flow containing wear fine particles generated from a rotary sliding portion such as a bearing portion and a seal portion from being mixed into a main liquid supply in a rotary pump subjected to a corrosion treatment; Providing a second blocking flow path for preventing the main liquid supply from entering the second blocking flow mechanism,
The first cut-off flow mechanism includes a first cut-off flow passage formed by a rotary shaft and an inner peripheral surface of a rotary shaft casing, and a first cut-off by a main liquid supplied partially into the rotary shaft casing from a pump space. In order to discharge the flow from the end of the first cut-off flow channel, the rotary shaft casing includes a discharge portion provided near the impeller, and a discharge passage connected to the discharge portion,
The second cutoff flow mechanism includes: a supply source of an inert liquid for a pump wetted portion as a second cutoff flow; a second cutoff flow that is sent into a rear rotary shaft casing; and a rotary shaft and an inner peripheral surface of the rotary shaft casing. To join the first cut-off flow through the second cut-off flow passage constituted by the first cut-off flow mechanism, and to discharge from the discharge passage of the first cut-off flow mechanism. And a supply path provided between the second cut-off flow supply source and the second cut-off flow supply port. pump. In the first cut-off flow mechanism located at the meeting point of the terminal portions flowing in opposite directions on the rotating shaft, the discharge portion is provided on the rotating shaft casing for storing the blocking disk provided on the rotating shaft of the pump and the pump. A pump comprising: a disc chamber; wherein the second cutoff has a higher hydraulic pressure at its supply port than the first cutoff. 3. The pump according to claim 2, wherein a labyrinth is formed on the blocking disk. The second blocking flow of an inert liquid flowing from the second blocking flow supply port is always filled in a portion of the rotary sliding portion in the rotary sliding portion where the anti-corrosion treatment cannot be performed, according to any one of claims 1 to 3, A pump that is insulated from the main liquid supply that may enter from the first cutoff flow channel. The mixed liquid volume of the first and second shut-off flows discharged from the common outlet is always larger than the second cut-off flow, the composition ratio is the second cut-off flow 1, and the first cut-off flow is at least 1.5 or more. .

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