JPH02184907A - Liquid temperature adjusting method - Google Patents

Abstract

PURPOSE:To perform the rise or fall of a liquid temperature gradually for constant time by accommodating liquid with different temperatures in two tanks in which the liquid can flow from one side to the other side mutually, and discharging the liquid accommodated in both tanks from either of the tanks. CONSTITUTION:The tanks 6 and 7 in which the liquid with different temperatures are accommodated, respectively, are communicated in such a way that the liquid can flow from the tank on one side to the tank on the other side. And pure water with different temperatures accommodated in both tanks is discharged with a flow rate set in advance only from the tank on one side i.e. the tank 7 in which the pure water is accommodated by communicating the tanks 6 and 7 with each other by opening a valve 14, and opening a valve 11 simultaneously, and driving a liquid sending pump 13. In such a way, the pure water whose temperature can be increased gradually can be obtained from the discharging side of the liquid sending pump 13.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is an extremely simple liquid solution that is applied when it is desired to gradually and continuously raise or lower the liquid temperature over a certain period of time. The present invention relates to a temperature control method.

<Conventional technology> In recent years, so-called ultra-large-scale integrated circuits, which remove as much as possible fine particles, colloidal substances, high-molecular organic substances, pyrogenic substances, etc., have been used in the fields of the electronic industry, medicine, and pharmaceutical industry, etc., where LSIs and VLSIs are produced. Pure water is used.

For example, ultrapure water used in the electronics industry is typically
It is manufactured by the following method.

That is, raw water is treated with a primary water supply system consisting of a coagulation sedimentation device, a sand filter, an activated carbon filter, a reverse osmosis membrane device, a two-bed three-column pure water production device, a mixed bed polisher, a precision filter, etc. Primary pure water is obtained, and the secondary pure water is further processed in a secondary water supply system consisting of membrane devices such as a hotbed polisher, ultraviolet irradiation device, precision filtration membrane device, and super filtration membrane device to produce ultrapure water. It is something. The obtained ultrapure water is sent via piping to the point of use, where it is used for cleaning semiconductor wafers or chips.

In the above-mentioned secondary water supply system, even though the water to be treated is pure water obtained from the primary water supply system, and despite the fact that ultraviolet rays are applied just before the point of use, it cannot be used for a long time. As the production of ultrapure water continues, the amount of viable bacteria and particles leaking into the ultrapure water increases and exceeds the permissible limit.

The cause of this is thought to be that a small amount of general bacteria that exist in ultrapure water and are resistant to ultraviolet rays gradually breeds inside the secondary water supply system channels such as the membrane device and subsequent use point piping. .

If the secondary water supply system, such as a membrane device or point-of-use piping, is contaminated with bacteria, the ultrapure water obtained will be unsuitable as water for cleaning, so some kind of sterilization treatment will be required. Conventionally, a method of sterilizing the secondary water supply system by flowing hot water into the secondary water supply system has been used.

Normally, the hot water sterilization treatment uses room-temperature pure water obtained from the above-mentioned secondary side water supply device as water, and the purified water is heated with a device such as the one shown in Fig. 2 to supply the secondary side water supply. It was being supplied to the network. That is, pure water at room temperature is introduced into the heat exchanger 2 through the pipe 1 by a water supply means such as a pump (not shown), and a heat medium such as steam or hot water is introduced into the heat exchanger 2 through the heat medium supply pipe. 3, the pure water is heated to a predetermined temperature, usually 70°C or higher, to produce hot pure water, and the hot wire water is supplied to the secondary water supply system line through piping 4 to produce hot water. Sterilize.

Furthermore, when such hot water sterilization treatment is completed, the supply of the heat medium to the heat exchanger 2 is stopped, and the pure water at normal temperature is supplied to the secondary water supply line again to start producing ultrapure water. do.

<Problems to be solved by the invention> As mentioned above, in hot water sterilization treatment, a heat exchanger etc.
Thermal pure water heated to above ℃ is supplied, and after the hot water sterilization is completed, room temperature pure water is supplied again into the secondary water supply system, but conventionally, temperature control at this time was performed by the operator. This was done by manual operation.

For example, by attaching a valve 5 to the heat medium supply pipe 3 in FIG. 2 and gradually increasing the opening degree of the valve 5 manually, the flow rate of the heat medium supplied to the heat exchanger 2 is gradually increased.
This is a method in which the temperature of the room-temperature pure water introduced into the heat exchanger 2 is gradually raised by such an operation.
Therefore, operations are extremely complicated, and the temperature tends to rise or fall rapidly, which causes excessive expansion and contraction of piping and equipment, as well as increases in pressure inside the pipes due to rapid temperature rises. There was a problem that the durability of the product was deteriorated.

In this way, it is common industrial practice to switch the liquid flowing through a system from a low-temperature liquid to a much higher-temperature liquid, or vice versa. However, in such cases, in order to reduce damage caused by temperature changes to the piping and equipment being used, avoid sudden temperature rises or falls as much as possible, and slowly drain the liquid over a certain period of time. It is essential to raise or lower the temperature.

To achieve this purpose, for example, the valve attached to the heat medium supply pipe 3 in FIG. 2 is made into a control valve whose opening degree can be adjusted mechanically or electrically, and This can be done by controlling, for example, a control means using a microcomputer or the like. That is, by controlling the control valve so that its opening degree increases stepwise over a certain period of time, the flow rate of the heat medium supplied to the heat exchanger 2 is gradually increased, and the flow rate of the heat medium supplied to the heat exchanger 2 is increased accordingly. The temperature of pure water introduced into the heat exchanger 2 at a constant flow rate can be gradually increased.

However, in this case, there is a problem that the instrumentation is extremely complicated and requires an expensive control mechanism.

The present invention has been made in view of the above-mentioned circumstances, and provides an extremely simple and inexpensive liquid temperature control that can gradually raise or lower the liquid temperature over a certain period of time. The purpose is to provide a method.

<Means for Solving the Problems> The present invention, which has been made to achieve the above object, stores liquids having different temperatures in two tanks in which the liquids communicate with each other so that they can flow, and This liquid temperature regulating method is characterized in that the liquid contained in both tanks is discharged from only one of the tanks.

<Effect> The present invention will be explained in detail below using the drawings.

FIG. 1 is a flow explanatory diagram showing an example of an embodiment of the present invention. In the figure, 6 and 7 indicate oaks for respectively storing liquids having different temperatures, and these two tanks are connected to a communication pipe 8. This allows liquid to flow from one tank to the other tank.

Further, a discharge pipe 10 is connected to the tank 6 via a valve 9, and a discharge pipe 12 is connected to the tank 7 via a valve 11, and these re-discharge pipes are connected to the downstream side of the valve 9 and the valve 11, respectively. After that, it is connected to the suction side of the liquid feeding pump 13.

Further, in FIG. 1, reference numeral 14 indicates a valve attached to the communication pipe 8, and reference numerals 15 and 16 indicate supply pipes for supplying liquid at a predetermined temperature into the tank 6 and the tank 7, respectively.

For example, hot water sterilization of the secondary water supply system of the ultrapure water production apparatus described above can be carried out in the following manner using the flow shown in FIG.

In addition, in the following explanation, thermally purified water at 80 degrees Celsius will finally be added to the secondary water supply system, which has been treating pure water at room temperature (temporarily 20 degrees Celsius) obtained from the primary water supply system. An example will be explained in which the temperature of the supplied pure water is gradually increased from 20° C. to 80° C. over 15 minutes during hot water sterilization.

First, with all the valves 9, 11, and 14 closed, hot pure water heated to 80°C by a heat exchanger or the like is supplied into the tank 6 through the supply pipe 15, and a predetermined amount of water is supplied into the tank 6. of hot pure water is stored in advance. On the other hand, in the other tank 7, there is a supply pipe 16.
20°C pure water (hereinafter referred to as cold pure water) is supplied through the
A predetermined amount of cold pure water is stored in the tank 7 in advance. On this occasion,
Both lines of water are stored so that the water surface levels of both tanks are approximately at the same level. Further, the discharge amount of the liquid pump 13 is set in advance so that almost the entire amount of the liquid contained in the two tanks can be discharged in 15 minutes.

Next, from this state, the valve 14 is opened to communicate the tanks 6 and 7, and at the same time, the valve 11 is opened, and the liquid feed pump 13 is driven to transfer the two lines of water at different temperatures stored in the two tanks to one side. Only the tank 7 containing cold pure water is discharged at a preset flow rate.

By such a method, it is possible to obtain pure water whose temperature gradually rises from 20° C. to about 80° C. over a period of 15 minutes from the discharge side of the liquid pump 13.

That is, immediately after the start of the above operation, pure water at a temperature of 20° C. is obtained from the discharge side of the liquid pump 13 because the cold pure water stored in the tank 7 is discharged. When the water level of tank 7 C falls due to the discharge of cold pure water and becomes lower than the water level of the hot pure water stored in tank 6 , tanks 6 and 7 are connected via valve 14 to communication pipe 8 . Because they are in communication with each other, the water levels in tanks 6 and 7 always try to maintain the same level, and as a result, hot pure water at 80°C continuously flows from tank 6 to tank 7 via communication pipe 8. The water level in both tanks always stays at almost the same level and falls. The temperature of the pure water in the tank 7 gradually rises due to the inflow of the hot pure water, so that it is possible to obtain pure water from the discharge side of the liquid pump 13 whose temperature gradually and continuously rises from 20°C. I can do it. Then, 15 minutes after the water initially stored in both tanks is almost completely exhausted, pure water at about 80° C. can be obtained from the discharge side of the liquid feed pump 13.

The pure water obtained from the discharge side of the liquid pump 13 as described above and whose temperature gradually rises from 20°C to about 80°C is
The water is directly supplied to the secondary water supply system. Note that when the temperature of the pure water obtained from the discharge side of the liquid sending pump 13 reaches approximately 80°C, that is, immediately before the pure water initially stored in both tanks runs out, the water in the tank 6 via the supply pipe 15 is At the same time, valves 11 and 14 are closed, and valve 9 is closed.
The tank 6 is opened and the hot pure water continuously supplied into the tank 6 is then discharged via the valve 9, the discharge pipe 10, and the liquid pump 13. With this operation, 80° C. hot pure water can be continuously supplied to the secondary water supply system, and the hot water sterilization process of the secondary water supply system can be performed without any problem.

The above-mentioned series of operations can be carried out by, for example, attaching level switches to both tanks, using normal automatic opening/closing valves as the valves, and connecting these level switches, automatic valves, and the liquid sending pump 13 with instrumentation. This can be easily done automatically.

Once the above hot water sterilization process is completed, the secondary water supply system is then supplied with pure water whose temperature gradually drops from 80°C to 20°C to gradually cool the secondary water supply system. However, in this case, contrary to the above-mentioned case of rising liquid temperature, valve 11 is closed, valve 14 and valve 9 are opened, and the pure water contained in both tanks is
Only the tank 6 containing the thermally purified water is discharged, or the pure water contained in both tanks is mutually exchanged so that the cold purified water is stored in the tank 6 and the thermally purified water is stored in the tank 7. It is sufficient to perform exactly the same operations as in the above case, and detailed explanation will be omitted.

In addition, in the above-mentioned embodiment, an example was shown in which the present invention was applied to hot water sterilization treatment of the secondary water supply line of an ultrapure water production device,
It goes without saying that the present invention is not limited to this, and can be applied to any case where it is desired to gradually raise or lower the liquid temperature over a certain period of time.

<Effects> As explained above, according to the present invention, liquids having different temperatures are stored in two tanks connected by a communication pipe, and the liquid is discharged from only one tank. A liquid whose temperature gradually and continuously increases or decreases from the temperature of the liquid stored in one tank to the temperature of the liquid stored in the other tank can be easily obtained, and therefore, for example, the liquid can be passed through the system. This method is extremely convenient as a method for adjusting the liquid temperature when switching from a relatively low temperature to a high temperature, and has the advantage that it can be carried out at low cost.

[Brief explanation of the drawing]

FIG. 1 is a flow explanatory diagram showing an example of an embodiment of the present invention, and FIG. 2 is a flow explanatory diagram showing an example of a conventional technique.

Claims (1)

[Claims] A liquid characterized by containing liquids having different temperatures in two tanks in which the liquids communicate with each other so that they can flow, and in which the liquid contained in both tanks is discharged from only one of the tanks. Temperature control method.