JPH0363411B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for preventing negative pressure inside the steam sterilization device and piping during cooling after steam sterilization in a steam sterilization system for the steam sterilization device. In particular, the present invention relates to a method for preventing the inside of a semipermeable membrane filtration device and piping from becoming negative pressure due to steam condensation after steam sterilization of a semipermeable membrane filtration device.

[Conventional technology]

For sterilization of semipermeable membrane filtration devices with pore diameters of 0.2 μm or less, hot water sterilization and sterilizing agents have traditionally been used. Spores are present, and hot water sterilization is insufficient, and methods that sterilize by sending a sterilizer into the equipment or pipes may cause the sterilizer to fill the equipment if there are structural air pockets in the pipes. There was a drawback that some areas were left unprotected and the sterilization of those areas was insufficient.

Steam sterilization was considered to solve the drawbacks of these conventional methods, but semipermeable membrane filtration equipment did not previously have a semipermeable membrane that could be used for in-line steam sterilization, but recently, in-line steam sterilization is possible. When a semi-permeable membrane was developed and steam sterilization was performed, negative pressure was generated inside the device during cooling after steam sterilization.
There was a problem in that unsterilized air from outside the device entered the device after steam sterilization through the seals of the device and piping, causing recontamination.

[Problem that the invention seeks to solve]

The present invention performs steam sterilization on a semipermeable membrane filtration device,
When cold water was run immediately after steam sterilization, seal leakage occurred due to differences in thermal expansion, so in order to put it into practical use, it was necessary to cool it naturally to below 100℃.
If the temperature drops below 100℃, the steam will rapidly condense, creating a negative pressure inside the device, and unsterilized air from outside the device will enter the device after steam sterilization through the seals of the device and piping, causing recontamination. This was done to solve the problem.

[Means for solving problems]

The present invention was made in order to solve the above-mentioned problems, and in a filtration device equipped with a semi-permeable membrane module, hot water is introduced from the raw water side of the filtration device during cooling after steam sterilization. This is to prevent negative pressure from forming on the side.

[Effect]

By pressurizing the equipment and piping to avoid negative pressure during cooling after steam sterilization, there is no risk of dirty air containing bacteria or pyrogens from outside the equipment and piping entering through seals such as piping connections. Therefore, it is possible to maintain a sterile state after steam sterilization.

〔Example〕

The present invention will be explained by means of embodiments shown in the drawings.
1 is a filtration device using Module 2, a semipermeable membrane made of polysulfone with a molecular weight cutoff of 6000, to remove bacteria and pyrogen from the raw water. 3 is a raw water tank, and raw water is supplied to the raw water tank 3 through a pipe 4 equipped with an automatic valve 20. Raw water is supplied from the raw water tank 3 to the filtration device 1 through a raw water supply pipe 6 equipped with a pressure adjustment valve 40 and an automatic valve 21 by a circulation pump 5, and is then pressurized and supplied to the semipermeable membrane module 2, which passes through a hollow fiber semi-transparent membrane. The water flows inside the permeable membrane and is returned to the raw water tank 3 through the raw water circulation pipe 7. The raw water circulation pipe 7 is equipped with an automatic valve 22 and a pressure adjustment valve 4.
1 is installed inside, and a flow meter F ₂ for measuring the amount of raw water returned through the raw water circulation pipe 7 is also installed.

While the raw water passes through the inside of the hollow fiber semipermeable membrane described above, a part of the raw water is transmitted to the outside of the membrane as water, and the water supply pipe 8 and the automatic valve 30 disposed in the water supply pipe 8 are activated. It passes through and is sent to the place where it is used. Reference numeral 9 denotes a withdrawal pipe which is branched from the raw water circulation pipe 7 and draws out a part of the concentrated raw water, and the withdrawal pipe 9 is equipped with a flowmeter F ₃ for measuring the amount of extracted water, a control valve 42 and an automatic valve 31. It's decorated.

10 is a steam supply pipe that supplies steam to the filtration device 1, and the steam supply pipe 10 includes, in order from the inlet side, a pressure gauge P ₄ , a restriction orifice 11 , a pressure reducing valve 12 , a pressure gauge P ₃ , and a 3 μm stainless steel A prefilter 13 made of metal, a safety valve 14, and an automatic valve 23 are provided.

Reference numeral 15 denotes a water extraction pipe connected to the lower part of the filter device 1, and an automatic valve 26 is installed in the extraction pipe 15.
and a steam trap _S1 , and a raw water supply pipe 6 that supplies raw water to the filtration device 1.
A drain pipe 16 used for draining water is frozen, and the drain pipe 16 is a discharge pipe 16 equipped with a valve 42, an automatic valve 27, and a condensate discharge pipe equipped with a steam trap _S2 . A pipe 16 ₂ is connected. Also,
Reference numerals 17 and 18 are a steam discharge pipe and a condensed water discharge pipe which are branched from the water supply pipe 8 to discharge sterilizing steam, and the steam discharge pipe 17 is equipped with a control valve 43 and an automatic valve 2.
8, the condensed water discharge pipe 18 is equipped with an automatic valve 29 and a steam trap _S3 .

Further, a pipe 19 is branched from the steam supply pipe 10 described above, and an automatic valve 25 is installed in the pipe 19, and the pipe 19 is inserted into the raw water tank 3 and the automatic valve 25 is opened to supply steam to the pipe 19. The raw water in the raw water tank 3 is heated, and the condensed water is discharged from the steam trap _S4 provided at the end of the pipe.

33 is a bypass pipe that communicates the raw water circulation pipe 7 with the vicinity of the outlet of the circulation pump 5 of the raw water supply pipe 6 connected to the circulation pump 5;
An automatic valve 32 is installed inside the bypass pipe 33.

In the figure, F ₁ is a flow meter installed in the raw water supply pipe 6 to measure the amount of raw water supplied, 34 is a level meter that senses the water surface of the raw water tank 3, and t ₁ is the raw water tank 3.
t2 is a thermometer that measures the temperature of the water side (secondary side), and _t2 is a thermometer that measures the temperature of the water side (secondary side).
is an automatic valve installed near the outlet of the raw water circulation pipe 7.

Since this embodiment is as described above, normally raw water is supplied from A and stored in the raw water tank 3, but in this case, the inside of the raw water tank 3 is automatically controlled by the signal from the level meter 34. The raw water in the raw water tank 3 is kept constant by opening and closing the valve 20. In order to pass the raw water through the filtration device 1, first, the automatic valve 21 of the raw water supply pipe 6 and the raw water circulation pipe 7 are opened and closed. Open the automatic valve 30 provided at the end of the automatic valve and water supply pipe 8, the automatic valve 31 of the concentrated water withdrawal pipe 9, open the automatic valve 32 of the bypass pipe 33, and open the automatic valve 31 of the concentrated water withdrawal pipe 9.
5. Valve 4 of pipe 16 ₁ branched from drain pipe 16
2 and pipe 16 ₂ , the automatic valve 28 of the steam discharge pipe 17, and the automatic valve 29 of the condensing pipe 18 are closed, and the raw water in the raw water tank that starts the circulation pump 5 passes through the valve 40 to reduce the flow rate. is supplied to the semipermeable membrane module 2 while being metered, flows inside the hollow fiber semipermeable membrane, and flows through the raw water circulation pipe 7 to the raw water tank 3.
Returning to the above, while passing through the inside of the hollow fiber semipermeable membrane, some of the raw water comes out as water to the outside of the membrane, but since this semipermeable membrane has a molecular weight cutoff of 6000,
The water, with bacteria and pyrogen removed, is sent through the water supply pipe 8 and automatic valve 30 to the location where it is used.

In addition, the raw water is returned to the raw water tank 3 through the raw water circulation pipe 7 as described above, but in order to draw out a part of the concentrated raw water, a concentrated water extraction pipe 9 is used to remove the valve 42 and the automatic valve 31. It is made to pass through and be discharged. The valves 40 and 41 installed in the raw water supply pipe 6 and the raw water circulation pipe 7 described above are valves for adjusting the pressure that pressurizes the semipermeable membrane module 2, and the valve 42 is for controlling the pressure of the semipermeable membrane module 2... This is a valve that adjusts the amount that is extracted.

Although sterilization is performed using the above-mentioned operations, the normal filtration is stopped and steam sterilization is performed about once every two weeks.
Automatic valve 2 installed in the raw water supply pipe 6
1. Close the automatic valve 22 installed in the raw water circulation pipe 7 and the automatic valve 30 of the water supply pipe 8, and close the filter device 1.
The automatic valve 26 of the water drain pipe 15, the automatic valve 27 of the condensed water discharge pipe ₁₆₂ , and the air vent valve 24 are opened, and the valve 43 of the steam discharge pipe 17 is slightly opened, and the automatic valve 28 is opened. Also, condensed water discharge pipe 1
The automatic valve 29 of 8 and the automatic valve 24 at the inlet of the raw water circulation pipe 7 are opened to draw out the raw water inside the semipermeable membrane and the water outside the semipermeable membrane.

When the above extraction is completed, the automatic valve 24 at the inlet of the raw water circulation pipe 7 is closed, and the automatic valve 23 of the steam supply pipe 10 is opened to supply steam from the inlet B. The inside of the hollow fiber semipermeable membrane (raw water side) is heated from room temperature to 121℃ for 10 to 10 minutes to avoid applying thermal shock to the semipermeable membrane.
Introduce for 15 minutes. This steam is transferred to pressure reducing valve 1
2 until the reading on the pressure gauge P ₂ becomes 1.2 kg/cmG, and a prefilter 13 made of 3 μm stainless steel sintered metal removes iron rust in the steam. As described above, the steam supply pipe 10 is provided with a restriction orifice 11 and a safety valve 14 as a safety measure in case an abnormal condition occurs.

The steam introduced inside the hollow fiber semipermeable membrane (raw water side) passes through the semipermeable membrane and flows into the water side, but at this time, the automatic valve 28 of the steam exhaust pipe 17
By opening the valve 43 of the pipe 17 slightly, the steam is blown out to the outside, thereby facilitating the flow of steam from the raw water side to the water side of the semipermeable membrane.

This steam sterilization is performed by keeping the temperature of the filtration device 1 and related piping at approximately 121°C for approximately 30 minutes.
At this time, the condensed water is discharged from the steam traps S ₁ , S ₂ , and S ₃ provided at the ends of the extraction pipe 15 , the water drain pipe 16 ₂ , and the condensed water discharge pipe 18 .

Steam sterilization is performed in a state where the air is elevated, and when the steam sterilization is completed, the automatic valve 2 installed in the steam supply pipe 10
3 and close the automatic valve 2 of the extraction pipe 15.
6, water drain pipe 16 ₂ automatic valve 27, steam discharge pipe 1
7 automatic valve 28 and condensate discharge pipe 18 automatic valve 2
9 is also closed to put the entire filter device 1 in a sealed state and begin cooling. However, as the filter device 1 cools, the pressure in the filter device 1 becomes negative, and the air outside the filter device 1 is sucked into the sterilized piping, etc. and becomes contaminated. To prevent this, hot water is introduced into the filtration device 1 to pressurize it. In an experiment using a test machine, it was found that after steam sterilization, when the product was cooled in a sealed state as described above, a negative pressure of about -250 mmHg was obtained, and when the product was left to stand still after that, the negative pressure decreased to about -110 mmHg.

To pressurize with the hot water described above, first, the automatic valve 25 installed in the pipe 19 communicating with the steam supply pipe 10 is opened to introduce steam into the heater in the raw water tank 3.
Heat the raw water in the raw water tank to approximately 50℃ or higher. In order to stir the raw water in the raw water tank 3 during this heating, the automatic valve 31 in the concentrate extraction pipe 9 is closed, and the raw water supply pipe 6 near the circulation pump 5 is communicated with the raw water circulation pipe 7. The automatic valve 32 of the bypass pipe 33 is opened, the circulation pump 5 is started, and the raw water tank 3 is adjusted with the regulating valve 44 of the bypass pipe 33.
The raw water inside is circulated through the bypass pipe 33 to maintain a temperature of about 50°C or higher.

When the raw water in the raw water tank reaches 50°C, preferably 80°C or higher, the automatic valve 32 of the bypass pipe 33 is closed, and the automatic valve 21 installed in the raw water supply pipe 6 and the raw water circulation pipe 7 is closed. The automatic valve 22 is opened, heated raw water is supplied into the filtration device 1 by the circulation pump 5, the semipermeable membrane is pressurized from the raw water side, and the water side is pressurized by the water that has passed through the semipermeable membrane. In this state, the circulation pump 5 is operated for about 30 minutes while the inside of the water side piping and the semipermeable membrane module are cooled down to room temperature.
is kept in a pressurized state while operating, and when the temperature reaches room temperature, an automatic valve 30 disposed at the end of the water supply pipe 8 is opened to supply water. When water is sent, the liquid level in the raw water tank drops, but the signal from the level meter 34 opens the automatic valve 20 installed in the pipe that supplies raw water to the raw water tank 3, and room temperature water is replenished. The temperature of the raw water in the tank 3 will drop, and continuous operation will result in normal overwork.

Since the embodiment of the present invention is configured as described above, in order to prevent the inside of the filtration device from becoming negative pressure and drawing in contaminated air etc. from the outside when the filtration device is cooled after steam sterilization, 50℃ or more preferably 80
Since hot water at about 0.degree. C. is introduced into the apparatus under pressure, there is no risk of contaminated air entering the apparatus or through seals such as pipe connections.

〔Effect of the invention〕

Due to the negative pressure prevention method of the present invention, there is no risk of outside air entering through seals such as piping connections during cooling after steam sterilization, so steam sterilization is more reliable without being contaminated by bacteria or pyrogen. becomes.

[Brief explanation of drawings]

The drawing shows a flow sheet of the negative pressure prevention method of the present invention. 1; filtration device, 2; module, 3; raw water tank, 5; circulation pump, 6; raw water supply pipe, 7; raw water circulation pipe, 8; water supply pipe, 9; concentrated water extraction pipe, 10; steam supply pipe , 11; restriction orifice,
12; pressure reducing valve, 13; prefilter, 14; safety valve, 20-32; automatic valve, 33; bypass pipe,
P ₁ ~ _{P 4} ; Pressure gauge, S ₁ ~ _{S 4} ; Steam trap,
t ₁ , t ₂ ; thermometer; F ₁ to F ₄ ; flow meter.

Claims (1)

[Claims] 1. In a filtration device equipped with a semipermeable membrane module, hot water is introduced from the raw water side of the filtration device during cooling after steam sterilization to prevent negative pressure on the water side of the filtration device. A method for preventing negative pressure in a steam sterilization system using a steam sterilization system. 2. A negative pressure prevention method in a steam sterilization system for a filtration device according to claim 1, characterized in that a polysulfone membrane is used as the semipermeable membrane module.