JP2001054785A - Evaporation type production of pure water nd device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase purity of pure water with high heat efficiency, in a production method of pure water by feeding raw water to a multiple-effect evaporating unit and evaporating. SOLUTION: This raw water is fed to a heat exchanger 6a of a final-effect evaporator 6 of the multiple-effect evaporating unit 1 as cooling water and stream evaporated by the multiple-effect evaporators 2, 3, 4 and 5 in the front effect is condensed and is taken out as pure water, while stream evaporated by the final-effect evaporator 6 is condensed at a condenser 13 and is taken out as clean water. Besides, the raw water after the evaporation at the final- effect evaporator 6 is fed to other effect evaporator 2, 3, 4 and 5 as water to be evaporated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to pure water used in various industries such as the electronics industry for cleaning or process water or boiler feed water, and industrial water or groundwater as raw water. The present invention relates to a method for producing by evaporating water and an apparatus therefor.

[0002]

2. Description of the Related Art Recently, as a method for producing pure water from raw water such as industrial water or groundwater, a method by evaporation, that is, the raw water is heated and evaporated, the water vapor is condensed, and the condensed water is condensed. The method of taking out as pure water is adopted, but in this method by evaporation, the dissolved gas, carbonic acid component and volatile component in the raw material water are gasified together with steam, and 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.

[0003] Therefore, Japanese Patent Application Laid-Open No. 3-26 as a prior art is disclosed.
No. 2585 discloses raw water such as industrial water or groundwater,
After performing pretreatment of degassing to remove dissolved gas and volatile components, and decarboxylation to remove carbonic acid components, it is proposed to produce pure water of high purity by supplying to the evaporator and evaporating. I have.

In order to increase the purity of the pure water produced, the raw water is supplied to an evaporator after the pretreatment for degassing and decarboxylation and then pure water is produced by evaporation. The rate of degassing and decarbonation in the pretreatment of the raw water must be increased.

[0005] For this purpose, in the prior art method, the raw water is brought into contact with the stripping steam supplied to the inside of the deaeration and decarbonation treatment apparatus at atmospheric pressure to thereby reduce the boiling point of the air. By increasing the temperature to a maximum, the degassing and decarbonation rates are increased.

[0006]

However, in this method, a part of the stripping steam supplied to increase the degassing and decarbonation rates, and the steam generated from the raw water by heating by the stripping steam. Is released into the atmosphere without being recovered, which results in heat loss, and thus has a problem of low thermal efficiency.

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

[0008]

Means for Solving the Problems In order to achieve this technical object, the production method of the present invention is a method for producing pure water by supplying raw water to a multiple-effect evaporator. It was 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 stage effect stage evaporator was condensed and taken out as pure water, while evaporating in the final effect stage evaporator. The steam is condensed and taken out as fresh water, and the raw 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 comprises: a multi-effect evaporator; a raw water means for supplying raw water as cooling water to a heat exchanger of a final-effect evaporator in the multi-effect evaporator; Pure water extracting means for extracting condensed water in the heat exchanger of the utility stage evaporator as pure water, fresh water extracting means for condensing steam evaporated in the final utility stage evaporator and extracting it as fresh water, And evaporating water supply means for supplying raw water after evaporation in the final effect stage evaporator to other effect stage evaporators as water to be evaporated. "

[0010]

The final effect stage evaporator in the multiple effect evaporator has a high degree of vacuum. Then, by supplying the raw water as cooling water to the heat exchanger in the last-effect-stage evaporator, the raw water is cooled at the same time as the heat exchanger and boiled at the vacuum degree. The gas and decarboxylation treatment can be performed at a high treatment rate in the final utility stage evaporator.

As described above, 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.
Boiling and evaporating in another utility stage evaporator, the generated steam reaches a heat exchanger in the final utility stage evaporator, and in this heat exchanger, cooling of raw water 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 last-effect-stage evaporator, the condensed water obtained by condensing the steam generated by the boiling of the raw water is:
Since it contains dissolved gas and carbonic acid components, this condensed water is taken out separately from the pure water as fresh water used for another purpose.

According to the present invention, the pretreatment for degassing and decarboxylation of the raw water is carried out at a high degassing and decarbonation 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 the stripping steam 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 is condensed and taken out as fresh water that can be used for purposes other than pure water, and thus has the effect of greatly improving thermal efficiency.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment.

In this figure, reference numeral 1 denotes a multiple effect evaporator, and these five effect stage evaporators, that is, 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. Each of these effect evaporators 2, 3, 4, 5, 6 is provided with a multi-tube heat exchanger 2 a, 3 a. , 4a, 5a, 6a
And sprayers 2b, 3b, 4b for spraying water to be evaporated on the outside of the heat exchangers 2a, 3a, 4a, 5a, 6a.
5b and 6b are provided.

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

The condenser 13 is connected to, for example, a vacuum pump or a non-condensable gas extracting means 15 comprising a steam ejector 15a and a condenser 15b.

Further, the water to be evaporated that accumulates at the bottom of the first effect stage evaporator 2 is passed through a pipe 16 to the second effect stage evaporator 3.
The water to be evaporated that accumulates at the bottom of the inside of the second effect stage evaporator 3 at the bottom of the third effect stage evaporator 4 via the pipe line 17 and at the bottom of the third effect stage evaporator 4 Evaporated water that accumulates at the bottom of the fourth effect stage evaporator 5 via a pipe 18 and evaporant water that accumulates at the bottom of the fourth effect stage evaporator 5 via a line 19 is the fifth effect stage evaporator. The water to be evaporated which is sequentially sent to the bottom in the can 6 and accumulates in the bottom in the fifth effect stage evaporator 6 is
Spreaders 2b, 3 in the first to fifth effect evaporators 2, 3, 4, 5 are supplied through a supply line 21 provided with a circulation pump 20.
b, 4b, and 5b are circulated. A part of the circulating water is blown down from a pipe line 22 so as to keep the concentration of the circulating water to be evaporated substantially constant.
Used for other applications.

Further, the condensed water in the heat exchanger 2a in the first effect stage evaporator 2 is passed through a pipe 23 into the heat exchanger 3a in the second effect stage evaporator 3, and the second effect stage evaporator. The condensed water in the heat exchanger 3a in the can 3 is passed through the pipe 24 into the heat exchanger 4a in the third effect stage evaporator 4, and
The 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 to the heat exchanger 6a in the fifth effect stage evaporator 6 via the pipe 26, and The condensed water in the heat exchanger 6 a of the evaporator 6 is configured to be extracted as pure water by a pure water extraction pump 27.

The raw water sent from the pipe 28, sulfuric acid, for example, from the pipe 29 and sodium sulfite from the pipe 30 are appropriately added to decompose residual chlorine and adjust pH. After that, the air is blown from the blower 31 to the decarbonation device 32 to which the air has passed, and after performing a certain degree of decarbonation, the supply pump 33 sends the air to the sprayer 6 b in the fifth effect stage evaporator 6. Supply.

In this configuration, the raw water sent from the pipe 28 is subjected to a certain degree of decarboxylation treatment, and then the cooling water is supplied to the outside of the heat exchanger 6 a in the fifth effect stage evaporator 6. Supplied as

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

As described above, the raw water deaerated and decarbonated in the final fifth-effect evaporator is evaporated to the other effect-stage evaporators 2, 3, 4, and 5 in the multiple-effect evaporator 1. Supplied as water, other utility stage evaporators 2,3
In the fourth and fifth embodiments, the fuel vapors and evaporates,
The heat reaches the heat exchanger 6a in the effect stage evaporator 6, and condenses in the heat exchanger 6a by cooling the raw water supplied as cooling water to the outside of 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, and 5a in the heat exchangers 4 and 5, the water is taken out from the pure water take-out pump 27 as pure water.

On the other hand, in the final fifth-effect-stage evaporator 6, steam generated by the boiling of the raw water is condensed into a condenser 13.
Since the condensed water condensed in the above contains dissolved gas and 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 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 contains
By adding an appropriate amount of the scale inhibitor through the pipe 34, the adhesion of the scale can be prevented.

Next, FIG. 2 shows a second embodiment.

The second embodiment is a case where the multiple effect evaporator is of a vapor compression type.

That is, of the multiple-effect evaporators 2, 3, 4, 5, and 6 in the multiple-effect evaporator 1, the fourth-effect evaporator 5 immediately before the final fifth-effect evaporator 6. A part of the steam generated in is extracted, compressed by a steam ejector 35, and supplied as a heat source into the heat exchanger 2a in the first effect stage evaporator 2, and other structures are as follows. This is the same as in 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 recovered steam is not supplied from the final fifth-effect-stage evaporator 6 containing a large amount of non-condensable gas, but from the fourth-effect-stage evaporator 5 with a small amount of non-condensable gas immediately before. This can 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 is used.
The condenser 13 is disposed outside the multiple effect evaporator 1, but the condenser 13 may be disposed inside the final fifth effect stage evaporator 6.

In the case of raw water having a low carbonic acid component, the heat exchanger 6a in the final fifth-effect stage evaporator 6 does not pass through the decarbonation device 32 as in the above-described embodiments. Just supply them.

[Brief description of the 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]

 DESCRIPTION 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 take-out pump 21 Supply line of evaporated water 27 Pure water take-out pump 28 Raw water supply pipeline

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D034 BA03 CA14 4D037 AA03 AB11 BA23 BB03 BB05 BB06 BB07 BB09 4D076 BA35 BC01 CB02 CB03 CB06 DA02 DA25 EA02Y EA12Y EA14Y EA18Y FA11 FA12 FA14 FA31 GA03 HA01 JA03

Claims (2)

[Claims] 1. A method for producing pure water by supplying raw water to a multiple effect evaporator, wherein the raw 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 utility stage evaporator is condensed and taken out as pure water, the vapor evaporated in the final utility stage evaporator is condensed and taken out as fresh water, and further, after evaporation in the final utility stage evaporator. An evaporative production method of pure water, wherein raw water is supplied to another utility stage evaporator as water to be evaporated. 2. A multiple effect evaporator, a raw water means for supplying raw water as cooling water to a heat exchanger of the final effect stage evaporator in the multiple effect evaporator, and a heat exchanger of the final effect stage evaporator. Pure water extracting means for extracting condensed water as pure water, fresh water extracting means for condensing steam evaporated in the final effect stage evaporator and extracting the condensed water as fresh water, and after evaporating in the final effect stage evaporator. And evaporating water supply means for supplying the raw material water to another utility stage evaporator as evaporating water.