JPS63264105A - Reciprocating pump for reverse-osmosis membrane concentrator - Google Patents

Abstract

PURPOSE:To reduce the total length of the title pump and to make the concentrator compact and lightweight by using a hollow shaft as the piston rod of the reciprocating pump, inserting a thread shaft to be rotated by a prime mover in the normal and reverse directions into the inside of the rod, and screwing a nut fixed to the piston rod on the thread shaft. CONSTITUTION:A reverse-osmosis membrane vessel 1 and the reciprocating pump 3 are connected by a closed-loop pipeline 15 in the reverse-osmosis membrane concentrator. In the pump, the piston rod 9 is formed with a hollow shaft, the thread shaft 11 to be rotated by the prime mover 13 in the normal and reverse diractions is inserted into the rod 9, and the nut 12 fixed to the piston rod 9 is screwed on the thread shaft 11. A piston 8 is reciprocated by the normal and reverse rotation of the thread shaft through a screw mechanism consisting of the thread shaft 11 and the nut 12. By this method, the length of the thread shaft and the length of the piston rod can be overlapped to the extent of one stroke of the piston, and the total length of the reciprocating pump is reduced by the overlapped length.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to reverse osmosis, in which a liquid to be concentrated is supplied to a reverse osmosis membrane under high pressure and separated into a permeated liquid that passes through the reverse osmosis membrane and a concentrated liquid that does not permeate. This invention relates to a reciprocating pump used in a membrane concentrator.

[Conventional technology and its problems]

Conventionally, this kind of reverse immersion! The concentrating device for ff5 is provided with a circulation pump in the middle of a closed loop pipe that connects the inlet and outlet of the liquid to be concentrated at one end of the reverse osmosis membrane tank and the inlet and outlet of the liquid to be concentrated at the other end. The liquid to be concentrated was supplied at high pressure (50 to 60 kg/an) using a pressure pump.

However, since this conventional reverse osmosis membrane concentrator requires two pumps, a pressure pump and a circulation pump, it has a complicated structure, becomes significantly large, and is quite expensive.
It turned out to be.

In contrast, the present inventors proposed a reverse osmosis membrane tank and a piston protruding from the cylinder in a patent application filed on March 16, 1988 (Japanese Patent Application No. 62-61639). It consists of a reciprocating pump that is reciprocated by a rod, and of both cylinder chambers in the reciprocating pump, the front cylinder chamber that does not have the piston rod is used as the inlet of the liquid to be concentrated in the reverse osmosis membrane tank. The rear cylinder chamber having the piston rod is connected to the outlet of the liquid to be concentrated in the reverse osmosis membrane tank to form a closed loop pipe between the reciprocating pump and the reverse osmosis membrane tank, and the closed loop pipe We have proposed a reverse osmosis membrane concentrator in which a liquid to be concentrated supply pipe and a liquid concentrate discharge pipe are connected to the pipe.

The reverse osmosis membrane concentrator according to this prior application can flow the liquid to be concentrated in the closed loop pipe between the reverse osmosis membrane tank and the pump using a single reciprocating pump. Since the liquid to be concentrated in the closed loop pipe can be pressurized to a high pressure, the reverse osmosis membrane concentrator can be made smaller and lighter than the conventional case, and can be provided at a lower cost.

However, in the reciprocating pump in the reverse osmosis membrane concentrator of the earlier application, a threaded shaft is coaxially connected to the tip of the piston rod, and a NAND screwed onto this threaded shaft is moved forward and backward by the prime mover. By rotating, the piston rod and thus the piston are configured to reciprocate with a small amount of power and a large output, and the length of the piston rod here is determined by adding the appropriate length to the stroke of the piston. In addition, the length of the screw shaft connected to this piston rod must be the same as the stroke of the piston. Therefore, the total length of a reciprocating pump is three times the stroke of the piston. In other words, since the total length of the reciprocating pump is long, it has not yet been possible to reduce the size, weight, and cost of reverse osmosis membrane concentrators.

The present invention provides that when the reciprocating pump in the reverse osmosis membrane concentrator of the prior application is reciprocated by a screw mechanism consisting of a threaded shaft and a screw threadedly fitted onto the screw shaft, the entire length of the reciprocating pump is By shortening the time, the reverse osmosis membrane concentrator can be made smaller, lighter, and lower in cost.

[Means to solve the problem]

Therefore, the present invention comprises a reverse osmosis membrane tank and a reciprocating pump in which a piston in a cylinder is reciprocated by a piston rod protruding from the cylinder, and one of the two cylinder chambers in the reciprocating pump is The front cylinder chamber without the piston rod is connected to the inlet of the liquid to be concentrated in the reverse osmosis membrane tank, and the rear cylinder chamber with the piston rod is connected to the outlet of the liquid to be concentrated in the reverse osmosis membrane tank. A reverse osmosis membrane concentrator comprising a closed loop pipeline between a dynamic pump and a reverse osmosis membrane tank, and a concentrated liquid supply pipeline and a concentrated liquid discharge pipeline connected to the closed loop pipeline, The piston rod of the reciprocating pump is formed into a hollow shaft, into which a screw shaft rotated forward and backward by a prime mover is inserted, and a nut fixed to the piston rod is fitted onto the screw shaft. It has a configuration that matches the above.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, reference numeral 1 indicates a reverse osmosis membrane tank equipped with a permeate extraction pipe line 2, and reference numeral 3 indicates a reciprocating pump with a relatively large capacity. .

This reciprocating pump 3 includes a cylinder 7 fastened between a pair of heads 4.5 by a plurality of stay bolts 6, and a piston 8 slidably inserted into the cylinder 7.
The piston 8 is provided with a hollow piston rod 9 that protrudes outside the cylinder 7, and is rotatably supported within the hollow piston rod 9 by bearings IO attached to each of the stay bolts 6. Insert the screw shaft 11
1, a NAND 1 fixed to the tip of the piston rod 9
2 are fitted and screwed together, while this screw shaft 11 is connected to the motor 13.
The piston 8 is configured to reciprocate by being connected to a prime mover via a shaft coupling 14 and rotated in forward and reverse directions by a motor 13.

Between the reverse osmosis membrane tank 1 and the reciprocating pump 3, a liquid to be concentrated 1a in the reverse osmosis membrane tank 1 and a front cylinder which does not have a piston rod 9 among both cylinder chambers in the reciprocating pump 3 are connected. It is connected to the chamber 7a via the first pipe line 15a, and the concentrated liquid outlet 1b in the reverse osmosis membrane tank l.
and the rear cylinder chamber 7b having the piston rod 9 out of both cylinder chambers in the reciprocating pump 3 are connected to the second pipe line 1.
5b to form a closed loop conduit 15.

A liquid to be concentrated supply line 16 is connected to the first line 15a of the closed loop line 15, and the piston 8 moves forward in the direction of the front cylinder chamber 7a into the liquid to be concentrated supply line 16. A liquid to be concentrated supply valve 17 in the form of a check valve is provided, which is closed only when the device is in motion.

On the other hand, in the second pipe line 15b in the closed loop pipe line 15,
The concentrate discharge pipe 18 is connected to the concentrate discharge pipe 1.
8, a concentrate discharge valve 19 is provided. This concentrate discharge valve 19 is related to the movement of the piston 8 in the reciprocating pump 3, and is closed when the piston 8 moves forward in the direction of the front cylinder chamber 7a. It is configured to open when retiring in the direction.

For example, the member 20 fixed to the piston rod 9,
A rotatable intermediate lever 21 is slidably fitted onto the stay bolt 6 to prevent the piston rod 9 from rotating.
This intermediate lever 21 is connected via a spring 22 to
and two interlocking pieces 23 and 24 slidably fitted onto the stay bolt 6, when the member 20 contacts one of the interlocking pieces 23 at the end of the forward movement of the piston 8. The concentrate discharge valve 19 is opened, and when the member 20 comes into contact with the other interlocking piece 24 at the end of the retraction movement of the piston 8, the concentrate discharge valve 19 is closed via wires 25, 26. Interlock and connect.

In this configuration, the piston 8 in the reciprocating pump 3 is rotated in the front cylinder chamber 7a by the forward rotation of the screw shaft 11.
When moving forward in the direction, the concentrate discharge valve 19 in the concentrate discharge pipe 18 connected to the second pipe 15b of the closed loop pipe 15 is closed, so that the front cylinder chamber of the reciprocating pump 3 is closed. The liquid to be concentrated in 7a is pushed out from the front cylinder chamber 7a, passes through the reverse osmosis membrane tank 1, and flows to the rear cylinder chamber 7b of the reciprocating pump 3. In this case, a piston rod 9 for reciprocating the piston 8 is present in the rear cylinder chamber 7b of the reciprocating pump 3, and the inner volume of the rear cylinder chamber 7b is equal to the content of the front cylinder chamber 7a. Since the volume of the piston rod 9 is smaller than the volume of the piston rod 9, the liquid to be concentrated in the closed loop pipe line 15 is less than the liquid to be concentrated due to the liquid to be concentrated supply valve 17 in the liquid to be concentrated supply pipe line 16 being closed. It is pressurized to a high pressure due to the difference in internal volume, and a part of it permeates through the reverse osmosis membrane in the reverse osmosis membrane tank 1, and from the permeate extraction pipe 2 in the reverse osmosis membrane tank 1, it flows into the front cylinder chamber 7a. While an amount of permeate corresponding to the difference between the internal volume and the internal volume of the rear cylinder chamber 7b, that is, the volume of the piston rod 9, is taken out, the rear cylinder chamber 7b contains 2! Concentrated liquid whose concentration has increased due to I-condensation flows in.

Next, when the piston 8 in the reciprocating pump 3 shifts from the forward movement toward the front cylinder chamber 7a to the backward movement toward the rear cylinder chamber 7b due to the reverse rotation of the screw shaft 11, the volume of the rear cylinder chamber 7b decreases. decreases, while the volume of the front cylinder chamber 7a increases, causing the liquid to be concentrated in the closed loop pipe 15 to flow from the rear cylinder chamber 7b to the front cylinder chamber 7a via the reverse osmosis membrane tank I. However, when the piston 8 is retracted, the concentrate discharge valve I9 is kept open during the day in the concentrate discharge pipe, so that the concentrate in the rear cylinder chamber 7b is removed from the concentrate. While being discharged from the discharge pipe 18 to the outside of the closed loop pipe 15, new liquid to be concentrated is sucked into the closed loop pipe 15 from the liquid to be concentrated supply pipe 16.

In this case, in the closed loop pipe 15, there is a connection part of the concentrated liquid supply pipe 16 to the closed loop pipe 15, and a concentrated liquid discharge pipe 1 to the closed loop pipe 15.
If a check valve 27 that opens only in the direction toward the rear cylinder chamber 7b is provided between the connecting portion of the piston 8 and the connecting portion of the piston 8, the piston 8 can be pushed out from the rear cylinder chamber 7b when the piston 8 moves backward. The check valve 2 prevents the concentrated liquid from being mixed with the new concentrated liquid sucked from the concentrated liquid supply pipe 16.
7, the concentrated liquid supply pipe 1
This makes it possible to avoid a decrease in the concentration ability due to mixing of a high concentration concentrate with the new liquid to be concentrated that is inhaled from 6, and to improve the concentration ability.

In the above embodiment, the motor 13 for rotating the screw shaft 11 is
is arranged at the tip of the screw shaft 11, and the motor 13
Although the output shaft of the motor 13 and the screw shaft 11 are directly connected via the shaft coupling 14, the output shaft of the motor 13 is The concentrate discharge valve 19 may be configured to transmit power to the screw shaft 11 via a power transmitter 14a such as a belt, a gear, or a chino. The opening/closing operation may be performed by other related means such as electrical connection, and the liquid to be concentrated supply valve 17 in the liquid to be concentrated supply pipe 16 may be of the check valve type (of the above embodiment). However, the opening/closing operation is not limited to this, and it is also possible to use one that opens and closes in conjunction with the reciprocating movement of the piston rod 9.

Furthermore, in the embodiment, the liquid to be concentrated supply line 16 is connected to the first line 15a in the closed loop line 15, and the concentrate discharge line 18 is connected to the second line 15b in the closed loop line 15, respectively. , the case where the connection part of the concentrated liquid discharge pipe 18 is located at a position closer to the rear cylinder chamber 7b than the connection part of the concentrated liquid supply pipe 16 is shown. The liquid discharge pipe 18 may be connected to the first pipe 15a or the second pipe 15b in the closed loop pipe 15, or the liquid to be concentrated supply pipe 16 may be connected to the front cylinder chamber 7a for supplying the concentrated liquid to the front cylinder chamber 7a. The same effect can be obtained even if the discharge pipes 18 are connected to the rear cylinder chambers 7b.

Therefore, in the claims of the present invention, the "concentrated liquid supply pipe connected to the closed loop pipe" includes, in addition to the case shown in the drawings, the concentrated liquid supply pipe 16 connected to the second pipe 15b. In addition, in the claims of the present invention, "connecting the concentrate discharge pipe to the closed loop pipe" includes the case where the concentrate discharge pipe is connected to the closed loop pipe. In addition, the concentrate discharge pipe 18 is connected to the first pipe 15a.
This includes cases where the cylinder is connected to the rear cylinder chamber 7b or the rear cylinder chamber 7b.

[Action/effect of the invention]

As described above, the present invention provides a reciprocating pump used in the reverse osmosis membrane concentration device of the prior application, in which the piston is reciprocated by a screw mechanism consisting of a screw shaft and a nut that is screwed into the screw shaft. When the piston rod is operated, the piston rod connected to the piston is formed into a hollow shaft, and a threaded shaft rotated forward and backward by a prime mover is inserted into the hollow shaft, and the threaded shaft is
A nut fixed to the piston rod is fitted and screwed together, and the piston can be reciprocated with a large output with a small power by forward and reverse rotation of the screw shaft. By inserting it into the hollow piston rod, the length of the screw shaft and the length of the piston rod can overlap by one stroke of the piston, so the total length of the reciprocating pump is equal to that of the earlier application. It is never more than twice the stroke of the piston, as in the case of a conventional piston, but it is only one stroke shorter.

Therefore, according to the present invention, a reciprocating pump and, by extension, a reverse osmosis membrane concentration device using the reciprocating pump can be made smaller and lighter, and can be provided at a lower cost.

[Brief explanation of drawings]

The drawing is a longitudinal sectional front view showing an embodiment of the present invention. 1... Reverse immersion i3 membrane tank, 2... Permeate extraction pipe,
3... Reciprocating pump, 7... Cylinder, 7a
...Front cylinder chamber, 7b...Rear cylinder chamber, 8...Piston, 9...Piston rod, 1
1... Screw shaft, 12... Nut, 13...
Motor, 15... Closed loop pipe line, 16... Concentrated liquid supply line, 17... Concentrated liquid supply valve, 18...
...Concentrate discharge pipe, 19...Concentrate discharge valve.

Claims (1)

[Claims] (1) Consisting of a reverse osmosis membrane tank and a reciprocating pump in which a piston in a cylinder is reciprocated by a piston rod protruding from the cylinder, the piston in both cylinder chambers of the reciprocating pump A front cylinder chamber without a rod is at the inlet of the liquid to be concentrated in the reverse osmosis membrane tank, and a rear cylinder chamber having the piston rod,
A closed loop pipeline is connected to the outlet of the liquid to be concentrated in the reverse osmosis membrane tank, and a closed loop line is formed between the reciprocating pump and the reverse osmosis membrane tank, and a liquid to be concentrated supply line and a concentrate line are connected to the closed loop line. In a reverse osmosis membrane concentration device connected to a liquid discharge pipe, the piston rod of the reciprocating pump is formed into a hollow shaft, and a screw shaft rotated in forward and reverse directions by a prime mover is inserted inside the piston rod. A reciprocating pump for a reverse osmosis membrane concentrator, characterized in that a nut fixed to the piston rod is fitted onto the threaded shaft.