JPH047253B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to 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. 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.

[Prior art]

Conventionally, sterilization of semipermeable membrane filtration devices with pore diameters of 0.2 μm or less has been carried out using boiling water sterilization or sterilizing agents, but sterilization with boiling water involves the existence of heat-resistant spores that cannot be killed by sterilization with boiling water at around 90°C. However, such boiling water sterilization is insufficient, and in addition, with the method of sterilizing by sending the sterilizer into the equipment or pipes, if there are air pockets in the pipes, the sterilizer will not fill the parts of the equipment. There was a drawback that sterilization of the area was insufficient.

Steam sterilization can be considered to solve the above-mentioned drawbacks of the conventional method, but in the past, there was no semipermeable membrane that could be used for in-line steam sterilization in semi-permeable membrane filtration equipment, but recently, in-line steam sterilization is possible. When a semi-permeable membrane was developed, steam sterilization was performed, and the inside of the device became negative pressure 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,
If cold water is poured immediately after steam sterilization, leakage will occur from the seal, so for practical use it is necessary to naturally cool the device to below 100℃.If the temperature drops below 100℃, the inside of the device will become negative pressure, causing damage to the device and piping. This was done in order to solve the problem that unsterilized air from outside the device enters the device after steam sterilization through the sealing portion, causing the inside of the device to become contaminated again.

[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 semipermeable membrane module, sterilized gas is introduced from the water side of the filtration device during cooling after steam sterilization, It is designed to prevent the water side of the filtration device from becoming negative pressure, and its implementation mode is to set the pressure of the introduced gas to 1 kg/cm ² G or less, and,
Air, nitrogen, and helium are used as the introduced gases.

[Effect]

By preventing negative pressure inside the filtration equipment and piping 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. It is possible to maintain a sterile state even after 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 cut off 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 the hollow fiber-like semi-permeable membrane module 2. The water flows inside the permeable membrane and returns to the raw water tank 3 via the raw water circulation pipe 7. The raw water circulation pipe 7 is equipped with an automatic valve 22 and a pressure adjustment valve 41, and is also equipped with a meter _F2 for measuring the raw water circulated through the raw water circulation pipe 7.

While the raw water passes through the inside of the hollow fiber semipermeable membrane described above, a part of the raw water permeates to the outside of the membrane and becomes water, passing through the water supply pipe 8 and the automatic valve 30 installed in the water supply pipe 8. and sent to the location where it will be 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 for measuring the amount of extracted raw water.
F ₃ , a control valve 42 and an automatic valve 52 are installed inside.

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,
Pressure gauge P ₃ , stainless steel sintered metal prefilter 13 with a pore diameter of 3 μm, safety valve 14 and automatic valve 23
is installed.

Reference numeral 15 denotes a water extraction pipe connected to the lower part of the filter device 1, and an automatic valve 2 is installed in the extraction pipe 15.
6 and a steam trap _S1 are arranged, and the raw water supply pipe 6 to the filtration device 1 is further extended to connect a water drain pipe 16 used for draining water, and the water drain pipe 16 is equipped with a valve. A discharge pipe 16 provided with 43, and an automatic valve 2
7. Connect the condensed water discharge pipe ₁₆₂ equipped with the steam trap _S2 . Further, 17 and 18 are a steam discharge pipe and a condensed water discharge pipe that discharge sterilizing steam branched from the water supply pipe 8. The steam discharge pipe 17 has a control valve 44 and an automatic valve 28, and the condensed water discharge pipe
is equipped with an automatic valve 29 and a steam trap _S3 .

31 is an air supply pipe connected to the water supply pipe 8, and the air supply pipe 31 includes a pressure gauge P ₅ for measuring the primary pressure of air, and an air pressure reducing valve for adjusting the secondary pressure of the air. 32. A pressure gauge P ₆ is installed to measure the secondary side pressure, and the air supply pipe 31 is equipped with a pre-filter 3 equipped with a filter made of cotton, for example, to remove dust, etc. from the air that is pressurized and supplied to the water side.
3. Polyvinyl alcohol pore size 0.2μ for sterilization
m main filter 34 and automatic valve 25 are arranged.

Further, in order to sterilize the main filter 34 described above, a steam connecting pipe 35 is provided to the main filter 34 to connect with the steam supply pipe 10, and a drain drain pipe 36 is further connected to the main filter 34 and the pre-filter 33. Ru. 46,47,4
Reference numerals 8, 49, 50, and 51 are switching valves installed in the air supply pipe 31, the steam connection pipe 35, and the drainage pipe 36.

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, 19 is a level meter that detects the water surface of the raw water tank 3, and T ₁ is the temperature of the raw water in the raw water tank. The thermometer to be measured, T ₂ , is a thermometer that measures the temperature on the water side (secondary side).
24 is an automatic pressurizing valve disposed in the raw water circulation pipe 7.

The embodiment of the present invention is constructed as described above, and normally raw water is supplied from A and stored in the raw water tank 3. In this case, the raw water inside the raw water tank 3 is controlled by the signal from the level meter 19. The raw water in the raw water tank 3 is always kept constant by opening and closing an automatic valve 20 in the liquid pipe.

In order to pass raw water through the semipermeable membrane filtration device 1, first, the automatic valve 21 of the raw water supply pipe 6, the automatic valve 22 of the raw water circulation pipe 7, the automatic valve 30 provided at the end of the water supply pipe 8, and the concentrated water Automatic valve 5 of extraction pipe 9
2 is opened, the automatic valve 26 of the pipe 15 is extracted from the water draining pipe 1, the valve 43 of the pipe 16 ₁ branched from the drain pipe 16, the automatic valve 27 of the pipe 16 ₂ , and the steam exhaust pipe 1.
When the automatic valve 28 of 7 and the automatic valve 29 of the condensing pipe 18 are closed and the circulation pump 5 is started, the raw water in the raw water tank passes through the valve 40, and the supply amount is measured by the flowmeter _F1 , while the semipermeable membrane module 2 is supplied,
Flowing inside the hollow fiber-shaped semipermeable membrane, the raw water circulation pipe 7
The water returns to the raw water tank 3, but while passing through the inside of the hollow fiber semipermeable membrane, some of the raw water exits as water to the outside of the membrane, but this semipermeable membrane has a molecular weight cut-off of
6000, the water is sent through the water supply pipe 8 and automatic valve 30 to the point where it is used, with bacteria and pyrogen removed.

Further, as mentioned above, the raw water is returned to the raw water tank 3 through the raw water circulation pipe 7, and a part of the concentrated raw water is drawn out using the concentrated water draw-out pipe 9. is performed by operating the valve 42 and automatic valve 52. 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 when pressurizing the semipermeable membrane modules 2, etc., and the valve 42 is for adjusting the pressure when pressurizing the semipermeable membrane modules 2, . It is used to adjust the amount of extracted raw water.

Although filtration is carried out by the above-mentioned operations, the normal filtration is stopped and steam sterilized about once every two weeks. To perform this steam sterilization, first, the circulation pump 5 is stopped, Close the automatic valve 21 installed in the raw water supply pipe 6, 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 automatic valve 26 of the water withdrawal pipe 15 from the filter device 1. The automatic valve 27 of the condensed water discharge pipe 16 ₂ and the pressurizing valve 24 disposed on the raw water circulation pipe 7 are opened, and the automatic valve 29 of the condensed water discharge pipe 18 is opened, and the steam supply pipe 10 is opened.
Automatic valve 23 is opened to supply steam from inlet B, but this steam is supplied in such a way that it does not give a thermal shock to the semipermeable membrane inside (raw water side) of the hollow fiber semipermeable membrane in filtration device 1. The heating time from room temperature to 121℃ is 10-15
Introduce it in minutes. This steam is transferred to the pressure reducing valve 12
The pressure gauge P ₂ was adjusted until the reading was 1.2 kg/cm ³ G, and iron rust, etc. in the steam was removed by a prefilter 13 made of stainless steel sintered metal with a pore diameter of 3 μm. A restriction orifice 11 and a safety valve 14 are provided as safety measures when an abnormal condition occurs in the steam supply pipe 10.

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
is opened, and the valve 44 of the pipe 17 is slightly opened to blow out the steam 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 steam traps S ₁ , S ₂ , and S ₃ disposed at the ends of the draw-out pipe 15 , the drain pipe 16 ₂ , and the condensed water discharge pipe 18 .

Steam sterilization is performed in the above-described state, and when the sterilization is completed, the automatic valve 23 provided in the steam supply pipe 10 is closed, and the automatic valve 26 of the draw-out pipe 15, the automatic valve 27 of the drain pipe ₁₆₂ , The automatic valve 28 of the steam discharge pipe 17 and the automatic valve 29 of the condensed water discharge pipe 18 are closed to seal the entire filter device 1 and begin cooling. Since there is a risk that outside air may be sucked into the sterilized pipes and the like and become contaminated, sterilized gas is introduced into the water side of the filtration device 1 and pressurized. In an experiment using a test machine, when cooled in a sealed state as described above after steam sterilization, approximately -250 mmHg
Negative pressure of about -110mm after leaving it for a while.
Development was observed in which the negative pressure decreased due to Hg.

Pressurization using the sterilized gas described above is performed through the air supply pipe 31 connected to the water supply pipe 8, but air, nitrogen, helium, etc. can be used as the introduced gas used for pressurization. but,
Since air is inexpensive and preferable, the explanation will be made assuming that air is used as the pressurized gas.

Air used for pressurization is introduced into the air supply pipe 31 from the inlet C, and adjusted to the pressure required for pressurization by the pressure reducing valve 32 while checking the pressure gauge P ₆ for measuring the secondary side pressure of the air. The air, which has been adjusted to the required pressure, passes through the pre-filter 33 to remove dust, etc., and is then sterilized by the main filter 34. However, when sterilizing the main filter 34, the steam that has passed through the filter 13 with a pore diameter of 3 μm installed in the steam pipe 10 is switched from the steam connecting pipe 35 connected to the steam pipe 10. The sterilization of the main filter 34 is performed by introducing the air into the main filter 34 via the valves 48, 49.
A switching valve 5 installed in the drain pipe 36 connected to the main filter 34 while opening the switch valve 5
0 and 51 are also open, and switching valves 45 and 46 are installed inside the inlet of the prefilter 33 of the air supply pipe 31 and between the prefilter 33 and the main filter 34,
This is carried out by closing the prefilter 33 and drain switching valve 47 and maintaining the temperature at 1.2 Kg/cm ³ G and 121° C. for 30 minutes.

After the main filter 34 has been sterilized, the switching valves 48, 49, 50, and 51 are closed, and the switching valves 45 and 46 are opened, and the air that has passed through the prefilter 33 and from which dust has been removed is removed. The air, which has been made sterile by passing through the steam-sterilized main filter 34, is introduced into the water supply pipe 8 by opening the automatic valve 25, and in this state, the water side pipe and the semi-permeable This is maintained while the membrane module 2 is cooled to room temperature.

When the temperature reaches normal temperature, the automatic valve 25 is closed,
While pressurizing the raw water side of the semipermeable membrane module 2 and passing water, the automatic valve 30 is opened to send water to the point of use, thereby returning to normal continuous filtering operation.

As mentioned above, in the present invention, the filtration device is steam sterilized, but membranes that can withstand steam sterilization are generally hydrophobic, and when the pressure is increased and the membrane is passed through the membrane, the semipermeable membrane is As the overcapacity decreases, it is necessary to introduce pressurized gas from the liquid side, and if the pressure of the pressurized gas exceeds 1 kg/cm ³ G, the membrane will dry and the amount of water after steam sterilization will decrease. Therefore, the pressure is preferably 1 Kg/cm ³ G or less.

〔Effect of the invention〕

The method for preventing negative pressure in the steam sterilization system of the filtration device according to the present invention eliminates the risk of outside air entering through seals such as piping connections during cooling after steam sterilization, which prevents bacteria and pyrogen from entering. Steam sterilization becomes more reliable without contamination.

Furthermore, since the gas such as air used is sterilized, the overcapacity of the semipermeable membrane module is not reduced.

[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, 10: steam supply pipe,
11: Limiting orifice, 12, 32: Pressure reducing valve, 1
3, 33: Pre-filter for air, 31: Air supply pipe, 34: Main filter for air, 35: Steam connection pipe, 36: Drain removal pipe, P ₁ to _{P 6} : Pressure gauge,
20-30...Automatic valve.

Claims (1)

[Claims] 1. In a filtration device equipped with a semipermeable membrane module, sterilized gas is introduced from the water side of the filtration device during cooling after steam sterilization, so that the water side of the filtration device becomes negative pressure. How to prevent overpressure in steam sterilization systems. 2. A method for preventing negative pressure in a steam sterilization system for a steam sterilization device according to claim 1, characterized in that the pressure of the introduced gas is 1 Kg/cm ² G or less. 3. A method for preventing negative pressure in a steam sterilization system for a filtration apparatus according to claim 1, characterized in that air, nitrogen, or helium is used as the introduced gas.