JP2620900B2 - High temperature pure water production equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-temperature ultrapure water used in the electronics industry such as the semiconductor industry, and a high-temperature pure water widely used as an alternative cleaning solution for chlorofluorocarbons and organic solvents in the precision and automotive industries. The present invention relates to improvement of a water production apparatus.

[0002]

2. Description of the Related Art Conventionally, as a method for producing pure water and ultrapure water, a method based on a membrane separation method and an ion exchange method has been mainly used. In recent years, the distillation method shown in FIG. 2 has a simple process, a small number of maintenances,
Attention has been paid to the fact that the quality of the produced water is constant, and it is suitable for producing high-temperature pure water or ultrapure water with strong detergency. In FIG. 2, (21) is a drain pump, (22)
Is a utility pump, (23) is a primary pure water pump, (24) is a utility pump, (25) is a secondary pure water pump, (26) is a UF module, (2)
7) is a UF module.

The present invention provides a new technology of a pure water or ultrapure water production apparatus based on a distillation method.

[0004]

In a pure water or ultrapure water production apparatus based on a distillation method, in addition to a technique for improving water quality, a high heat efficiency is maintained, and a heat transfer area which affects the scale and production cost of the apparatus is reduced. The most important technical issue is how to balance the two conditions that conflict with each other.

[0005] The present invention does not reduce the thermal efficiency,
It is intended to provide a measure for reducing the heat transfer area of a high-temperature pure water or high-temperature ultrapure water production apparatus.

[0006] The temperature of the production water is selected so as to provide an optimum cleaning effect in applications such as semiconductor cleaning. However, in the prior art, the design conditions of the multi-effect distillation unit changed each time.

The present invention provides a high-temperature pure water producing apparatus in which the design conditions of a multi-effect distillation unit are constant irrespective of the temperature of produced water.

[0008]

A high-temperature pure water producing apparatus according to the present invention is a high-temperature pure water producing apparatus provided with a multi-effect distillation apparatus, wherein a condenser for condensing steam generated in a final effect can has a steam condensing temperature. Is set as low as possible to the cooling water temperature, and a heater for heating the medium-temperature pure water or ultrapure water generated by condensation to a predetermined temperature is provided outside the multiple effect distillation apparatus. It is a feature.

In the primary pure water production system constituted only by the solid line portion in FIG. 2, pure water having a resistivity of about 15 MΩ · cm (as a value when cooled to 25 ° C.) is produced. In an apparatus to which a broken line portion, that is, an ultrapure water production system is added (in this case, a cooling water circulation line of a primary pure water distillation apparatus and a primary pure water extraction line having a primary pure water pump are not required), city water is used as raw water and resistance is reduced. Rate 18MΩ ・ c
m or more of ultrapure water is produced.

[0010] The primary pure water distillation unit and the ultrapure water distillation unit of these units are multiple effect distillation units as shown in FIG. FIG. 3 exemplifies a method of producing ultrapure water using primary pure water produced by an existing pure water apparatus using an ion exchange method or the like as raw water for simplification of the description. In the case of the system based on the combination of the two-stage distillation methods shown in FIG. 2, the operation is the same as that of FIG. 3 in each distillation apparatus.

[0011]

According to the high temperature pure water producing apparatus of the present invention, the final utility
In the condenser that condenses water vapor generated in the can , the water vapor condensation temperature is set as low as possible to the cooling water temperature to produce medium-temperature pure water or ultrapure water, and then medium-temperature pure water or ultrapure water. By heating water to a predetermined temperature by a heater, desired high-temperature pure water or high-temperature ultrapure water is produced.

[0012]

Next, the operation of the present invention will be described based on an embodiment.

First, the operation of the prior art shown in FIG. 4 will be described for comparison.

The temperature for taking out high-temperature ultrapure water is preferably in the range of about 60 to 95 ° C. in order to enhance the cleaning effect of semiconductors and the like and maintain an aseptic state at all times.
0 ° C. The condensation temperature of the heated steam was set to a safe atmospheric condensation temperature of 100 ° C.

The number of utility cans (utility number) is desirably as large as possible in order to increase the thermal efficiency, but is desirably small in order to reduce the cost of the apparatus. 5 effects. As a practical example of the thermal efficiency in this case, the desalination ratio (= production water volume / heating steam volume = 4) is practical. The temperature of the cooling water is 32 ° C. at the inlet according to the standard design conditions of the cooling tower in Japan. 37 ° C at the outlet
And

In order to make the description more concrete, if the amount of water produced as ultrapure water is 1000 kg / hour and the water recovery in this part is 80%, the supply amount of primary pure water is 1250 kg / hour. The drainage rate of 250 kg / hour is determined, and the heating steam rate of 250 kg / hour is determined from the assumed fresh water production ratio.

Here, in roughly examining the heat transfer area which is a factor affecting the scale and manufacturing cost of the apparatus,
For the sake of simplicity, it is assumed that the amount of heat exchange in each utility can (assuming the preheater is also installed in each utility) and the condenser (1) are equal, and that the overall heat transfer coefficient is also equal. (This assumption is that in order to actually produce ultrapure water,
Although too rough, there is no problem in explaining the operation of the present invention).

Then, the heat transfer area of each effect can and the condenser is inversely proportional to the heat transfer temperature difference in each effect.

The average temperature difference (ΔT _E ) in the utility can is as follows: ΔT _E = (T _s −T _w2 ) / N = (100−80) / 5 = 4 ° C. where T _s is the condensing temperature T of the heated steam. _w2 is the condensation temperature in the condenser N is the utility number, respectively.

The temperature difference in the condenser is

[0021]

(Equation 1)

[0022]

The total heat transfer area is

[0024]

(Equation 2)

[0025]

Here, Q _M is the heat transfer amount in each utility U is the average overall heat transfer coefficient a _A is the unit heat transfer amount and the heat transfer area per unit heat resistance, respectively.

The amount of heat exhausted from the condenser is Qc = 66,000 kcal / hour from the overall heat balance.

An example of the present invention will be specifically described with reference to FIG.

The apparatus for producing ultrapure water according to the present invention comprises a multiple effect distillation apparatus. A multi-effect distillation device is a multi-effect distillation device
(2) It mainly comprises a plurality of utility pumps (9), an ultrapure water pump (10) and a vacuum device (4).

The primary pure water is supplied to a preheating tube (5) running through each effect can in the still (2), and a vertical heat transfer tube of each effect can is provided.
(7) Heated by receiving a part of the latent heat of condensation of the water vapor generated in the tank, and further heated by a preheating pipe (5) in the first effect can receiving part of the latent heat of condensation of the heated steam to a temperature of 125 ° C or higher. It is heated to a temperature and enters the water reservoir (13) at the bottom of the first effect can. Pool (13)
The supplied water is mixed with the remaining concentrate that has generated steam in the heat transfer tube (7), and most of this mixture is
Upper water chamber located above the first utility can through (6) (3)
Supplied to This mixed solution flows down in a thin film form in the heat transfer tube (7), receives most of the latent heat of condensation of the heated steam from the outer surface of the tube, and evaporates at a temperature of 125 ° C. or more to generate steam. The concentrated liquid that has generated steam flows down to the water reservoir (13), mixes with the supply water as described above, and most of it is sent to the upper water chamber (3) via the circulation pump (6).

The remaining liquid mixture enters the second effect can reservoir (13) through the communication port (14), where the heat transfer tube (7) is again provided.
The mixture is mixed with the concentrated liquid flowing down, and most of the mixture is sent to the second effect can upper water chamber (3) via the second effect can circulation pump (6).

The steam generated in the heat transfer tube (7) of the first effect can enters the second effect can via the mist separator (15). The mist is removed by the mist separator (15) so that the mist accompanying the water vapor becomes extremely small. Most of the purified water vapor is condensed on the outer surface of the heat transfer tube (7) of the second effect can, and the condensate is collected in the condensate collecting section (not shown) in the second effect can, ie, the secondary pure water, that is, It is stored as pure water. The remaining water vapor is condensed on the outer surface of the second effect can preheating tube (5), and the condensate is mixed with the condensate from the heat transfer tube (7) in the condensate collecting section, and all of the condensate is contained in the third effect can. The secondary water or ultrapure water enters the collection unit. The steam generated in the n-th utility can, after the mist is removed by the mist separator (15), the preheating tube (5)
Is condensed on the outer surface of the heat exchanger and the outer surface of the heat transfer tube of the condenser (1), and is stored as ultrapure water in the secondary pure water reservoir (11) of the final utility can.

Thus, the above process is repeated for each effect can, and finally the condensate is collected in the secondary pure water reservoir (11) below the condenser (1) close to the n-th effect can of the still, From here, it is derived as ultrapure water of extremely high purity through the ultrapure water pump.

In this embodiment, the condenser (1) for condensing the water vapor generated in the final utility can is set so that the water vapor condensation temperature is as low as possible to the cooling water temperature, and the medium temperature generated by the condensation is reduced. A heater (16) for heating pure water or ultrapure water to a predetermined temperature is provided outside the multi-effect distillation apparatus.
It is provided in. In consideration of the available cooling water temperature, the condensation temperature in the condenser (1) is lowered to make the heat transfer temperature difference between each effect can and the condenser (1) substantially equal, and the ultrapure water taken out is separately separated. It is heated to a high temperature ultrapure water of 80 ° C by an ultrapure water heater (16). Other conditions are the same as those in FIG.

The average temperature of the cooling water in the condenser is represented by T _CM =
_Assuming that the heat transfer temperature difference in the condenser is approximately ΔT _c = T _w2 −T _CM , the average heat transfer temperature difference in each effect can and the condenser is as _follows : 1/2 (T _cw1 + T _cw2 ) .

[0036]

(Equation 3)

[0037]

The condensation temperature of the embodiment shown in FIG. 1 is higher than the condensation temperature of 80 ° C. of the prior art shown in FIG.
_{W2 = T CM + ΔT C =} 34.5 + 10.9 = 45.4 ℃ and lower, when correcting only the heat exchange rate is increased for the same amount of condensation in the condensation latent heat increases, Q'c = Qc · (Δh45.4 ° C / Δh80 ° C) = 66,000 x 572 / 551.5 = 68,453 Kcal / hour.

The amount of heat from the overall heat balance (= Qs'') = thermal emissions from the condenser + takeout heat = Q _{water' C + Fw · (T w2} -T w1) · Cw = 68,453 + 1250 × (45.4 -25) × 1.0 = 68,453 + 25,500 = 93,953Kcal / h heating steam quantity (effect _{evaporator) = Qs' / Δh 100 ℃} = 93,953 / 539 = 174.3 kg / time heating amount Q _H = 1000 in ultrapure water heater ( 80-45.4) 1.0 = 34,600Kcal / time heating steam quantity in ultrapure water heater = 64.2kg / when the total heating amount _{= Qs '' + Q H =} 93,953 + 34,600 = 128,553 Kcal / when the total heating amount of water vapor = 238.5kg / when the average amount of transferred heat Q _M '= 1/2 (Qs' in each effect evaporator and condenser '+ Qc') = 1/2 ( 93,953 + 68,453) = 81,203Kcal / when the total heat transfer area in the present invention

[0040]

(Equation 4)

[0041]

Is as follows.

In summary, according to the embodiment of the present invention shown in FIG. 1, the heat transfer area is smaller than that of the conventional method shown in FIG.

[0044]

(Equation 5)

[0045]

The heating steam amount is Qs' / Qs = 128,553 / 134,700 = 0.954.
(A 4.6% decrease).

That is, it is possible to greatly reduce the total heat transfer area without increasing the amount of heated steam (actually but slightly).

[0048]

According to the high-temperature pure water producing apparatus of the present invention, in the condenser for condensing the steam generated in the final utility can , the steam condensing temperature is set low so as to be as close as possible to the cooling water temperature, and the medium temperature pure water is set. By producing water or ultrapure water and then heating the medium temperature pure water or ultrapure water to a predetermined temperature by a heater, desired high temperature pure water or high temperature ultrapure water can be produced.

As a result, the following items are possible.

Contrary to the above embodiment, it is possible to greatly increase the thermal efficiency by increasing the number of utilities without changing the total heat transfer area.

As an intermediate method between them, the thermal efficiency can be increased to some extent, and at the same time, the total heat transfer area can be reduced to some extent.

Even if the requirement for the temperature for taking out high-temperature ultrapure water changes, it is only necessary to change the design of the ultrapure water heater.

It is clear that the same effect can be obtained when producing high-temperature pure water from city water or when producing high-temperature ultrapure water from city water by two-stage distillation.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing an embodiment of the present invention.

FIG. 2 is a flow sheet showing a configuration showing a conventional ultrapure water production method.

FIG. 3 is a flow sheet showing a configuration showing a conventional ultrapure water production method.

FIG. 4 is a flow sheet showing a form showing a conventional ultrapure water production method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Condenser 2 Multiple effect still 16 Heater

Continuation of the front page (72) Inventor Hidetaka Sawada 5-3-28 Nishikujo, Konohana-ku, Osaka-shi Inside Tachibashi Shipbuilding Co., Ltd. (72) Inventor Takashi Hirano 5-28-28 Nishikujo, Konohana-ku, Osaka-shi Hitachi Inside Shipbuilding Co., Ltd. (72) Inventor Shoichi Momose 5-3-28 Nishikujo, Konohana-ku, Osaka

Claims (1)

(57) [Claims] 1. A high-temperature pure water producing apparatus provided with a multiple-effect distillation apparatus, wherein a condenser for condensing steam generated in a final-effect can is set to have a low steam condensing temperature as close as possible to a cooling water temperature. A high-temperature pure water production apparatus, wherein a heater for heating medium-temperature pure water or ultrapure water generated by condensation to a predetermined temperature is provided outside the multiple effect distillation apparatus.