JPS62160106A - Method and device for separating membrane by supplying low temperature water - Google Patents

Abstract

PURPOSE:To control propagation of microbes and germs, reduce the the number of times for sterilizing and cleaning, decrease penetration speed of salt, prepare penetrating water of high purity and prevent a membrane from getting compacted by maintaining a device including membrane module under a low temperature. CONSTITUTION:After introducing water from a water supply pipe 1 into a filter 3 of a pretreatment device 2 and removing suspension from the supplied water, the water is cooled down by means of heat exchanging with low temperature penetrating water and concentrated water by a sub-heat exchanger 4. Further, after the water is cooled down by being passed through a cooler 8 in which refrigeration mediums such as Freon cooled by a refregerator 5, the same is guided from a pipe 9 into a membrane module 11 of the reverse osmosis pressure device through a high pressure pump 10 for membrane separation. Penetrating water and concentrated water formed in the membrane module 1 are still cold, and to recover cold heat, the said penetrating water and the concentrated water are passed from pipes 12 and 13 into the sub-heat exchanger 4 for being cooled down and then taken out of pipes 14 and 15.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention can provide sterile and highly pure permeated water for a long period of time, which is required in various fields such as food, pharmaceutical, medical, and electronic industries.
The present invention relates to a membrane separation method and apparatus that stably obtain membrane separation.

(Prior art) In reverse osmosis type desalination equipment, generally when the temperature of the feed water decreases, the viscosity coefficient of the water increases, and the permeation rate of water through the membrane decreases, so high temperature operation is desirable, but the temperature is too high. Since the hydrolysis effect and compaction phenomenon of the membrane becomes significant, the operating temperature is lower than that of the prior art, JP-A-49-13.
As seen in Publication No. 5888, the water temperature is always between 20°C and 3°C.
The temperature is controlled using an absorption refrigerator to maintain the temperature at 0°C.

However, at this water temperature, bacteria and microorganisms are likely to proliferate, causing clogging, and furthermore, there is a high possibility that the membrane will be damaged and its performance will be reduced.

(Problems to be Solved by the Invention) Permeated water obtained using a reverse osmosis desalination device has recently been in increasing demand as pure water, especially in the electronics industry, and as sterile water in the pharmaceutical field. However, as mentioned above, microorganisms and bacteria can easily proliferate at room temperature, so as a countermeasure, the membrane module must be regularly sterilized and cleaned, and during this time the supply of permeated water is interrupted, making the operation complicated. was there. Furthermore, in the recent electronic industry, it cannot be said that water permeated at conventional temperatures is necessarily of sufficiently high purity, and the demand for high purity is increasing.

(Means for Solving the Problems) In view of the above, the present invention suppresses the proliferation of microorganisms and bacteria by keeping the device including the membrane module at a low temperature, reduces the number of sterilization and cleaning operations that were often performed in the past, and In addition, by lowering the temperature to a lower temperature, the salt permeation rate is reduced to obtain filtered water with a lower concentration, in other words, a high purity, and furthermore, the purpose is to prevent compaction of the membrane.

-a The compaction rate of the membrane is related to the water temperature and operating pressure as shown in the following equation, and the lower the water temperature, the smaller the rate of decrease in permeated water over time.

Consolidation rate of membrane ocpα・tβ P: Operating pressure t: Water temperature α, β: Membrane constant depending on membrane material For example, in the case of a polyamide hollow fiber membrane, the reduction ratio of the amount of permeated water due to membrane consolidation is the first The trend shown in the figure is shown.

The present invention is based on the above knowledge, and uses a refrigerant in a refrigerator to suppress the growth and reproduction of bacteria and microorganisms.

For example, after being cooled to around 5°C, it is sent to a reverse osmosis desalination equipment, where it permeates at a low temperature, and the still cooled permeated water and concentrated water retain their cold heat to pre-cool the feed water and recover heat.
The gist is that feed water from which pollutants have been removed through pretreatment is sent to a heat exchanger, where it is heat exchanged with low-temperature permeate water and/or low-temperature concentrated water introduced from a reverse osmosis desalination device, and then further heated with low-temperature refrigerant. The low-temperature feed water is further cooled by exchanging heat with the water, and the feed water maintained at a low temperature is sent to a reverse leaching membrane module, and the generated low-temperature permeate water and concentrated water are returned to the heat exchanger. This is a membrane separation method that consists of a water supply inlet provided in the casing, a filtration layer located below it, a passed water heat transfer tube bundle, a concentrated water heat transfer tube bundle, and a refrigerant placed downstream thereof. A low-temperature pretreatment device equipped with a heat transfer tube bundle and a lower water supply outlet is used for freezing (function and effect). In the present invention, the supply water from which pollutants have been removed by pretreatment such as TF + It exchanges heat with a low-temperature refrigerant, cools it to around 5℃, and then sends it to the reverse osmosis desalination equipment, which suppresses the growth of microorganisms and bacteria compared to conventional operation that maintains the temperature at 20 to 30℃, and achieves high purity. of permeated water, which can fully meet the demands of the electronics and pharmaceutical fields.

Moreover, the permeated water obtained here =? Since the H1ii water is both low temperature, this cold energy is used for pre-cooling by exchanging heat with the feed water after pretreatment, which has a small effect on maintaining the low temperature of the reverse osmosis device, and improves the thermal efficiency of the refrigerator. It is useful for

In addition, the pretreatment device has a temporary layer in the upper part of the casing.
Since the heat transfer tube bundles for permeated water, concentrated water, and low-temperature refrigerant, which have cold heat, are provided below, the feed water after IJ12 is first precooled by the upper permeated water and concentrated water heat transfer tube bundles, and then cooled by the refrigerant heat transfer tube bundles. ℃, and if the heat transfer tube bundles are arranged at right angles, the falling feed water will be rectified, making heat transfer even more effective, and the filtration layer and heat exchanger will be integrated. Since it is housed inside the casing, it becomes a compact device, which has the effect of reducing the surface area and suppressing the amount of heat dissipation.

(Example) The figure shows an example of the present invention, and in FIG. The refrigerant, such as Freon, passes through the side heat exchanger 4 and is cooled by heat exchange with low-temperature permeated water and concentrated water, which will be described later, and is further cooled in the refrigerator 5. 5 passing through a cooler 8 which circulates via an outlet pipe 7
After being cooled to around 0.degree. C., it is introduced into a membrane module 11 of a reverse osmosis device through a pipe 9 via a high-pressure pump 10, and subjected to membrane separation.

Since the permeated water and concentrated water generated in the membrane module 11 are still in a cold state, in order to recover this cold energy, they are passed through the side heat exchanger 4 through pipes 12 and 13, respectively, and used for cooling the feed water, and then 14. Take it out from 15.

A filter unit 3 is provided, permeation main heat exchanger tube bundles 17 having a water chamber 16 at the bottom thereof are arranged horizontally, and a concentrated water heat exchanger tube bundle 19 having an ice chamber 18 below it is arranged horizontally and at right angles to form a membrane module. A refrigerant heat exchanger tube bundle 21 having a water chamber 20 connected to the refrigerator 5 below is installed so as to intersect at right angles to the horizontal direction, and water is supplied from the upper water supply pipe l to γμ After uniformly passing through the heat exchanger tube 3, the main heat exchanger tube bundle 17. The concentrated water tube bundle 19 is allowed to flow down for preliminary cooling, and then heat exchanged with the lower refrigerant heat transfer tube bundle 21 to cool it down to around 5°C, after which it is taken out from the tube 9 and passed through a high pressure pump as in the case of Fig. 2 to the membrane module. In this case, each heat transfer tube bundle is arranged at right angles, so the flowing water is rectified and efficiently exchanges heat. Furthermore, the entire device is compact, and the heat exchanger tubes are arranged at right angles. The heat dissipation area is small (which is advantageous in terms of thermal economy).

[Brief explanation of drawings]

FIG. 1 is a graph showing a trend in the amount of permeated water over time due to compaction of the membrane, FIG. 2 is a flow sheet in an embodiment of the present invention, and FIG. 3 is a perspective view of the main parts. 1... Water supply pipe, 2... Pretreatment device, 3
...Filter, 4...Side heat exchanger, 5.
... Refrigerator, 6... Inlet pipe, 7... Outlet pipe, 8... Cooler, 10... High pressure pump, 11... Membrane module, 17... Permeation main heat exchanger tube bundle, 19... Concentrated water heat transfer tube bundle, 21... Refrigerant heat transfer tube bundle. Patent applicant Sasakura Machinery Co., Ltd. Figure 3

Claims (2)

[Claims] (1) Feed water from which pollutants have been removed through pretreatment is sent to a heat exchanger, where it is heat exchanged with low-temperature permeated water and/or low-temperature concentrated water introduced from a reverse osmosis desalination device, and then further heated with low-temperature refrigerant. Membrane separation using low-temperature feed water, characterized in that the feed water is further cooled by heat exchange, the feed water maintained at this low temperature is sent to a reverse osmosis membrane module, and the generated low-temperature permeate water and concentrated water are returned to the heat exchanger. Method. (2) a water supply inlet provided in the casing, a filtration layer located below it, a permeated water heat transfer tube bundle, a concentrated water heat transfer tube bundle, and a refrigerant heat transfer tube bundle placed further downstream thereof; A membrane separation device using low-temperature water supply, in which a low-temperature pretreatment device equipped with a water supply outlet at the bottom is connected to a refrigerator and a reverse osmosis membrane module.