JPH0767556B2 - Sterilization method by heat generation of pump of ultrapure water and aseptic pure water production equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sterilization method using heat generated by a pump in an apparatus for producing ultrapure water and aseptic pure water.

Ultrapure water is used, for example, as washing water in a semiconductor manufacturing process, and is required to have a specific resistance value and a water quality close to theoretical pure water without impurities such as bacteria, fine particles, and organic substances.
In addition, sterile pure water is used in the pharmaceutical industry, medicine, cosmetics, fermentation,
It is used in place of conventional distilled water and sterilized purified water for raw water and washing water in the chemical or food industry. The production of ultrapure water or sterile pure water is usually carried out by a membrane separation technique using a reverse osmosis membrane (RO), an ultrafiltration membrane (UF), an ultraprecision filtration membrane (SF) or the like.

By the way, in these ultrapure water and sterile pure water production apparatuses, in order to guarantee sterility and pyrogen-free,
It is necessary to take sterilization measures and maintain the aseptic condition. In particular, when the apparatus is stopped such as on a holiday or at night and water is retained in the system, microorganisms and bacteria grow in the system, particularly in the membrane module, so that it is necessary to use a sterilizer. Therefore, in general, the raw water is stored in a tank, and the circulating water is usually heated to 85 ° C to 95 ° C by a heat exchanger or a method of constantly circulating it again to the tank through an ultraviolet sterilizer and a sterilization filter. A method of storing water at a high temperature is used.

As a conventional example implementing such a method, low pressure circulation through the ultraviolet sterilizer without stopping the water even during the pause and stop period, or by automatically performing intermittent flushing at low pressure and high flow rate for several minutes at regular intervals There is a method of discharging accumulated water inside the apparatus, particularly inside the membrane module, to the outside of the system.

An example of a method of heating by using a heat exchanger and circulating at high temperature through a tank is shown in FIG. 2 of the accompanying drawings. In FIG. 2, A is a tank, and a pump B is arranged at the outlet side thereof, and the raw water in the tank A is passed to the ultrafiltration device C by this pump B, and the permeated water is passed through the permeated water outlet side of the ultrafiltration device C. In addition, the concentrated water outlet side of the ultrafiltration device C communicates with the tank A through the heat exchanger D.
The heat exchanger D is supplied with steam from a steam generation source (not shown) via a valve E. As a result, the circulating water is heated to the required temperature when flowing from the concentrated water outlet side of the ultrafiltration device C to the tank A, and thus the circulating water becomes hot water and circulates in the system to perform a sterilizing action. Has been

It has also been proposed to use other heating means such as a heater as the heating means instead of the above heat exchanger.

[Problems to be Solved by the Invention] By the way, in the case of using an ultraviolet sterilizer, it is needless to manage the lamp of the ultraviolet sterilizer. The rate of sterilization may be reduced and the sterilization efficiency may be reduced. Therefore, it is necessary to always keep the quartz tube in contact with water in a clean state. Therefore, it is necessary to regularly remove and clean the quartz tube, which is not only time-consuming in terms of management, but also may cause contamination.

Further, in the conventional example as illustrated in FIG. 2, a special heat energy source is required, and moreover, since the water in the entire system including the tank is heated to a required temperature, a considerable amount of energy is required. Since it is necessary to return the warmed water to room temperature when restarting the normal pure water production operation, it is normal to discard the water in the system, especially the tank, and supply new water to restart the operation. is doing. Therefore, there is a problem that running cost is considerably high. However, in practice, when the equipment is stopped, such as on a holiday or at night, and water accumulates in the system, the problem is that the liquid separation membrane is rather than the microorganisms or bacteria present or growing in the entire system water. How to prevent the growth of microorganisms and fungi in the membrane module of the device.

Therefore, an object of the present invention is to provide water only to the pipe line portion including the membrane module without circulating the water throughout the system when the apparatus stops and the water stays in the system such as on a holiday or at night. Ultrapure water that can circulate and can significantly reduce running costs by using the exhaust heat of the circulation pump without using a special heat energy source to heat water, and sterilization by heat generation from the pump of an aseptic pure water production system To provide a method.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a tank for storing pretreated raw water, a pump connected to the outlet side of the tank, and the pump are used. A liquid physical membrane device having ultrapure water for filtering raw water supplied from the tank and delivering it as sterile pure water, aseptic water supply outlet, and concentrated water outlet for delivering concentrated water, the pump and the above In the ultrapure water and sterile pure water production apparatus having a closed pipeline on the concentrated water side that passes through the liquid separation membrane device, when the filtration operation is stopped,
It is characterized in that the water existing therein is circulated by the pump in the closed pipeline on the concentrated water side, and at the same time the temperature is raised by the heat generated by the pump to sterilize the hot water.

An ultrafiltration membrane module or a reverse osmosis module can be used as the separation membrane of the liquid separation membrane device.

[Operation] In the sterilization method by the pump heat generation of the ultrapure water and aseptic pure water production apparatus according to the present invention configured as described above, a closed pipe line passing through the pump and the liquid separation membrane device is provided so that the tank is not passed through. Since the water is circulated, the total amount of water circulated is relatively small, so that the heat of the pump can sufficiently heat the circulated water to a temperature necessary for suppressing the growth of microorganisms and bacteria. Thereby, the growth of microorganisms and fungi in the membrane module of the liquid separation membrane device can be effectively suppressed.

Further, when restarting the operation, a relatively small amount of water circulating at a high temperature may be returned to room temperature or discarded, and in this case, the water in the tank may or may not be discarded.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. 1 of the accompanying drawings.

FIG. 1 shows the structure of the essential parts of an apparatus for producing ultrapure water and aseptic pure water according to the present invention. Reference numeral 1 denotes a tank lever 1 which is water pretreated by a pretreatment system not shown in the tank 1. Is supplied.
The outlet side of the tank 1 is connected via a pump 2 to the inlet side of an ultrafiltration device 3 constituting a liquid separation membrane device, and the permeated water outlet side of this ultrafiltration device 3 communicates with a pure water supply passage 4. ,
A concentrated water outlet side is connected to an upstream side of the pump 2 through a pipe line 5 to form a circulation path passing through the ultrafiltration device 3 of the pump 2.

In the apparatus of the illustrated embodiment configured in this way, during normal operation, the water from the tank 1 is sent to the ultrafiltration device 3 by the pump 2, filtered through the membrane module of the ultrafiltration device 3 and purified. It is supplied to the water supply passage 4. In this case, the concentrated water can be returned to the upstream of the pump 2 through the line 5. On the other hand, when the apparatus is stopped such as on a holiday or at night, the pipe line leading from the tank 1 to the pump 2 is blocked by a valve or the like (not shown), whereby the pump 2 and the ultrafiltration apparatus 3 are separated. The water existing therein is circulated by the pump 2 in the circulating circuit, and the circulating water is circulated by the pump 2.
It is heated to a predetermined temperature by the heat generation of. In this way, in particular, the growth of microorganisms and fungi in the membrane module of the ultrafiltration device 3 can be effectively suppressed. In this case, even if the amount of water to be circulated is controlled according to the calorific value of the pump used, or the amount of water to be circulated is determined in advance and the output of the pump is controlled to circulate the water in the required temperature range. You may make it possible to heat. It should be noted that the pump 2 to be used can naturally be set so as not to heat the water above a predetermined temperature by its own heat generation during normal operation, that is, during the production of pure water.

[Effects of the Invention] As described above, according to the present invention, in the apparatus for producing ultrapure water and aseptic pure water, a tank is provided by providing a closed pipeline on the concentrated water side that passes through the pump and the liquid separation membrane device. Since the water is circulated without passing through it, the total amount of water circulated can be relatively small, and therefore the heat of the pump heats the circulated water sufficiently to the temperature necessary to suppress the growth of microorganisms and bacteria. can do. With this, it is possible to effectively suppress the growth of microorganisms and bacteria in the membrane module, without using a special heating means or sterilizing means as in the conventional device,
Sterilization can be performed, and as a result, not only the labor for management can be saved, but also the energy cost can be reduced and the apparatus can be simplified, and ultrapure, sterile pure water can be purified at low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a schematic diagram showing an example of a conventional device. In the figure, 1: tank, 2: pump, 3: ultrafiltration device, 5: pipeline.

Claims (1)

[Claims] 1. A tank for storing pretreated raw water, a pump connected to the outlet side of the tank, the raw water supplied from the tank by the pump is filtered and delivered as ultrapure water or sterile pure water. Ultrapure water, a sterile pure water outlet and a liquid separation membrane device having a concentrated water outlet for delivering the concentrated water, and a closed pipe path on the concentrated water side that passes through the pump and the liquid separation membrane device, When the filtration operation is stopped, the water existing in the closed pipeline on the concentrated water side is circulated by the pump and at the same time the temperature of the water is raised by the heat generated by the pump to perform hot water sterilization. Sterilization method by pump heat generation of ultrapure water and aseptic pure water production equipment.