JP3434474B2 - Evaporative production method and apparatus for pure water - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses pure water used for various purposes such as washing water or process water or boiler feed water in various industries such as electronic industry as industrial water or ground water as raw material water. The present invention relates to a method for manufacturing by evaporating water and an apparatus therefor.

[0002]

2. Description of the Related Art Recently, as a method for producing pure water from raw material water such as industrial water or groundwater, a method by evaporation, that is, by heating the raw material water to evaporate and condense the water vapor, Although the method of extracting as pure water is adopted, the method by evaporation is that the dissolved gas, carbonic acid component and volatile component in the raw water are gasified together with the steam, and are re-dissolved in the condensed water with the condensation of the steam. Therefore, the purity of pure water taken out as condensed water was low.

Therefore, Japanese Patent Laid-Open No. 3-26 is a prior art.
2585 discloses that raw water such as industrial water or ground water is
Proposed to produce high-purity pure water by performing degassing to remove dissolved gas and volatile components and decarbonation to remove carbonic acid components, and then supplying it to an evaporator to evaporate. There is.

By the way, when the raw water is subjected to the pretreatments for degassing and decarbonation and then supplied to the evaporator to produce pure water by evaporation, in order to raise the purity of the produced pure water, The degassing and decarboxylation rate in the pretreatment of the raw material water should be increased.

For this reason, in the method of the prior art, the raw material water is brought into contact with the stripping steam supplied to the degassing and decarbonation apparatus at atmospheric pressure to bring the boiling point in the atmosphere into consideration. By increasing the temperature to as high as possible, the degassing and decarboxylation rates are increased.

[0006]

However, in this method, a part of the stripping steam supplied for increasing the degassing and decarboxylation rate and the steam generated from the raw material water by the heating by the stripping steam. Was released into the atmosphere without being recovered, and this was a heat loss, so there was a problem of low thermal efficiency.

An object of the present invention is to provide a manufacturing method by evaporation of pure water which solves this problem, and an apparatus therefor.

[0008]

In order to achieve this technical object, the production method of the present invention is as follows: "In a method for producing pure water by supplying raw material water to a multi-effect evaporator, the raw material water is It is supplied as cooling water to the heat exchanger of the final effect stage evaporator in the multiple effect evaporator, and the vapor evaporated in the previous effect stage evaporator is condensed and taken out as pure water, while it is evaporated in the final effect stage evaporator. The steam is condensed and taken out as fresh water, and further, the raw material water after evaporation in the final effect stage evaporator is supplied to other effect stage evaporators as water to be evaporated. "

Further, the production apparatus of the present invention includes a "multi-effect evaporator, raw water means for supplying raw water to the heat exchanger of the final effect stage evaporator in the multi-effect evaporator as cooling water, and the final water. Pure water removing means adapted to take out condensed water in the heat exchanger of the effect stage evaporator as pure water, and fresh water removing means adapted to condense the vapor evaporated in the final effect stage evaporator to take out as fresh water, It is characterized in that it is provided with an evaporated water supply means for supplying the raw material water after evaporation in the final effect stage evaporator to other effect stage evaporators as evaporated water. "

[0010]

The action and effect of the invention The final effect stage evaporator in the multiple effect evaporator has a high degree of vacuum. Therefore, by supplying the raw material water as cooling water to the heat exchanger in the final effect stage evaporator, the raw material water is cooled at the same time as the heat exchanger is cooled and the water is boiled at the degree of vacuum. The gas and decarbonation treatment can be carried out at a high treatment rate in the final effect stage evaporator.

In this way, the raw water degassed and decarbonated in the final effect stage evaporator is supplied to other effect stage evaporators in the multiple effect evaporator as water to be evaporated,
In the other effect stage evaporator, it is boiled and evaporated, and the generated steam reaches the heat exchanger in the final effect stage evaporator, and in this heat exchanger, cooling of the raw material water is supplied to the heat exchanger as cooling water. After being condensed in, it is taken out as pure water.

On the other hand, in the final effect stage evaporator, the condensed water obtained by condensing the steam generated by boiling of the raw material water is
Since it contains a dissolved gas and a carbonic acid component, this condensed water is taken out as fresh water used for another purpose separately from the pure water.

According to the present invention, as described above, the pretreatment of degassing and decarbonation of the raw material water is performed at a high degassing and decarboxylation rate in the final effect stage evaporator of the multiple effect evaporator as described above. In addition to the fact that it is not necessary to supply stripping steam in order to raise the temperature of the raw water to the boiling point in the atmosphere as described above, the raw water was evaporated from the raw water for the degassing and decarbonation treatment. The steam condenses it and takes it out as fresh water that can be used for purposes other than pure water, and therefore has the effect of greatly improving the thermal efficiency.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment.

In the figure, reference numeral 1 denotes a multiple-effect evaporator, and five effect-stage evaporators, namely, a first-effect-stage evaporator 2, a second-effect-stage evaporator 3, and a third-effect-stage evaporator. 4, a fourth effect stage evaporator 5 and a fifth effect stage evaporator 6 are provided, and each of these effect evaporators 2, 3, 4, 5, 6 has a multi-tube heat exchanger 2a, 3a. , 4a, 5a, 6a
And the sprayers 2b, 3b, 4b for spraying the water to be evaporated on the outside of the heat exchangers 2a, 3a, 4a, 5a, 6a.
It is equipped with 5b and 6b.

In the heat exchanger 2a of the first effect stage evaporator 2, steam from the boiler is supplied as a heating source from the steam supply pipe 7, and steam generated in the first effect stage evaporator 2 is in the duct 8 The steam generated in the second effect stage evaporator 3 into the heat exchanger 3a in the second effect stage evaporator 3 via the duct and into the heat exchanger 4a in the third effect stage evaporator 4 via the duct 9. , The steam generated in the third effect stage evaporator 5 passes through the duct 10 and the heat exchanger 5 in the fourth effect stage evaporator 5
The steam generated in a and in the fourth effect stage evaporator 5 is respectively introduced into the heat exchanger 6a in the fifth effect stage evaporator 6 via the duct 11, and The steam generated in the effect stage evaporator 6 is guided to the condenser 13 via the duct 12, condensed there, and then taken out from the fresh water take-out pump 14 as fresh water.

The condenser 13 is connected to, for example, a vacuum pump or a non-condensable gas extraction means 15 including a vapor ejector 15a and a condenser 15b.

Further, the water to be evaporated, which collects at the bottom of the first effect stage evaporation can 2, is passed through the pipe 16 to the second effect stage evaporation can 3
At the bottom of the third effect stage evaporator, the water to be evaporated that collects at the bottom of the second effect stage evaporator 3 is transferred to the bottom of the third effect stage evaporator 4 via the conduit 17 and to the bottom of the third effect stage evaporator 4 via the conduit 17. The water to be evaporated is collected at the bottom of the fourth effect stage evaporator 5 via the pipe 18, and the water to be collected at the bottom of the fourth effect stage evaporator 5 is evaporated at the bottom of the fifth effect stage via the pipe 19. The water to be evaporated, which is sequentially sent to the bottom of the can 6 and collects at the bottom of the fifth effect stage evaporation can 6,
In the supply line 21 provided with the circulation pump 20, the sprayers 2b, 3 in the first to fifth effect evaporators 2, 3, 4, 5
b, 4b, 5b is configured to circulate, and a part of this circulating water is blown down from the pipe line 22 so as to keep the concentration of the circulated evaporated water substantially constant,
Used for another purpose.

Furthermore, the condensed water in the heat exchanger 2a in the first effect stage evaporator 2 is transferred to the second effect stage evaporator in the heat exchanger 3a in the second effect stage evaporator 3 via the conduit 23. Condensed water in the heat exchanger 3a in the can 3 passes through the pipe 24 into the heat exchanger 4a in the third effect stage evaporation can 4
Condensed water in the heat exchanger 4a in the effect stage evaporator 4 passes through the pipe 25 to the heat exchanger 5a in the fourth effect stage evaporator 5
Inside, the condensed water in the heat exchanger 5a in the fourth effect stage evaporator 5 is sequentially sent into the heat exchanger 6a in the fifth effect stage evaporator 6 via the pipe 26, and then the fifth effect stage. Condensed water in the heat exchanger 6a in the evaporator 6 is taken out as pure water by the pure water take-out pump 27.

Then, the raw material water sent from the pipe 28 is appropriately added with, for example, sulfuric acid from the pipe 29 and sodium sulfite from the pipe 30 to decompose residual chlorine and adjust the pH. After that, the air is blown from the blower 31 to the decarbonation device 32, and a certain amount of decarbonation is performed. Then, the supply pump 33 supplies the sprayer 6b of the fifth effect stage evaporator 6 to the sprayer 6b. Supply.

In this structure, the raw material water sent from the pipe 28 is decarbonated to some extent, and then cooled to the outside of the heat exchanger 6a in the fifth effect stage evaporator 6. Supplied as.

The raw material water supplied here cools the heat exchanger 6a in the fifth effect stage evaporator 6 having a high degree of vacuum and, at the same time, boils at the degree of vacuum. The decarboxylation treatment can be performed at a high treatment rate in the final fifth effect stage evaporator.

In this way, the raw water that has been degassed and decarbonated in the final fifth effect stage evaporator is evaporated in the other effect stage evaporators 2, 3, 4, 5 in the multiple effect evaporator 1. Other effect stage evaporators 2, 3, supplied as water
At 4 and 5, it is boiled and evaporated, and the generated steam is
It reaches the inside of the heat exchanger 6a in the effect stage evaporator 6 and is condensed by cooling the raw material water supplied as cooling water to the outside of the heat exchanger 6a in the heat exchanger 6a. In this heat exchanger 6a, other effect stage evaporators 2, 3,
Along with the condensed water collected from the heat exchangers 2a, 3a, 4a, 5a in 4,5, pure water is taken out from the pure water taking-out pump 27.

On the other hand, in the final fifth effect stage evaporator 6, the steam generated by boiling of the raw material water is condensed by the condenser 13
Since the condensed water condensed in step 1 contains a dissolved gas and a carbonic acid component, this condensed water is taken out from the fresh water take-out pump 14 as fresh water used for another purpose separately from the pure water.

When the raw material water sent from the pipe 28 contains scale components such as calcium and / or silica, the water to be evaporated in the circulation pipe 21 is
By adding an appropriate amount of scale inhibitor from the conduit 34, it is possible to prevent the scale from adhering.

Next, FIG. 2 shows a second embodiment.

The second embodiment is a case where the multi-effect evaporation device is a vapor compression type.

That is, among the effect stage evaporators 2, 3, 4, 5, 6 in the multiple effect evaporator 1, the fourth effect stage evaporator 5 which is one before the final fifth effect stage evaporator 6 is used. Part of the steam generated in the above is extracted, compressed by the steam ejector 35, and supplied as a heat source into the heat exchanger 2a in the first effect stage evaporator 2; other structures are: This is the same as the first embodiment.

According to the second embodiment, a part of the steam generated in the multiple-effect evaporator 1 can be recovered as a heating source, so that the thermal efficiency can be improved.
In this case, the vapor to be recovered is not from the final fifth-effect stage evaporator 5 having a large amount of non-condensable gas, but from the fourth effect-stage evaporator 5 having a small amount of non-condensable gas one before. As a result, it is possible to reliably prevent the purity of pure water from decreasing.

In each of the above embodiments, the condenser 1 for condensing the vapor generated in the final fifth effect stage evaporator 6
In the case where 3 is arranged outside the multiple-effect evaporator 1, the condenser 13 may be arranged inside the final fifth-effect evaporator 6.

In the case of raw water containing a small amount of carbonic acid component, the heat exchanger 6a in the final fifth effect stage evaporator 6 does not have to pass through the decarbonation device 32 as in the above embodiments. It only has to be supplied.

[Brief description of drawings]

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

FIG. 2 is a flow sheet showing a second embodiment of the present invention.

[Explanation of symbols]

1 Multiple effect evaporator 2,3,4,5,6 effect stage evaporator 2a, 3a, 4a, 5a, 6a heat exchanger 13 condenser 14 Fresh water extraction pump 21 Supply line for evaporated water 27 Pure water extraction pump 28 Supply line for raw water

Continuation of the front page (56) Reference JP 48-18159 (JP, A) JP 62-160182 (JP, A) JP 60-255101 (JP, A) JP 58-95501 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 1/04 B01D 1/26

Claims (2)

(57) [Claims] 1. A method for producing pure water by supplying raw material water to a multiple effect evaporator, wherein the raw material water is supplied as cooling water to a heat exchanger of a final effect stage evaporator in the multiple effect evaporator. Then, while the vapor evaporated in the previous effect stage evaporator is condensed and taken out as pure water, the vapor evaporated in the final effect stage evaporator is condensed and taken out as fresh water, and further after evaporation in the final effect stage evaporator. A method for producing pure water by an evaporation method, characterized in that raw material water is supplied to another effect stage evaporator as water to be evaporated. 2. A multi-effect evaporator, raw water means for supplying raw water to the heat exchanger of the final effect stage evaporator in the multiple effect evaporator as cooling water, and a heat exchanger for the final effect stage evaporator. Pure water removing means for taking out the condensed water as pure water, and fresh water taking out means for taking out the vapor evaporated in the final effect stage evaporator as fresh water, and after evaporating in the final effect stage evaporator And a means for supplying water to be evaporated as water to be evaporated to another effect-stage evaporator, the apparatus for producing pure water by evaporation.