JPH0568809A - Membrane deaeration equipment and raw water deaeration method - Google Patents

Abstract

PURPOSE:To obtain small-scale, membrane deaeration equipment and a deaeration method for producing deaerated water of low concentration of dis solved oxygen by continuously operating a membrane module to circulate excess deaerated water through the membrane module, a deaerated water tank and a raw water tank in this order. CONSTITUTION:A water supply pump 6 for conveying raw water W to a membrane module 3 is continuously operated irrespective of the quantity of deaerated water supplied to the outside to return excess deaerated water Wr to a raw water tank 1 through a water level difference operated value 16. As a result, the less quantity of the dearated water supplied to the outside Wo, the more quantity of the deaerated water returned to the raw water tank 1 W1, and the ratio of the deaerated water quantity to a total water supply quantity Wp by the water supply pump 6 is increased to notably decrease the concentration of dissolved oxygen. The continuous operation of the water supply pump 6 made at all time provides the extremely stable operation of the membrane module 3 and at the same time, the use of equipment at full capacity to obtain deaerated water deaerated to a high degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a membrane type deaerator, which is mainly used for improving the water quality of boiler feed water. Further, the present invention is also used for prevention of red water from water supply and corrosion of pipes, prevention of food collapse and oxidation, production of ultra-high purity cleaning water for semiconductor production, and the like.

[0002]

2. Description of the Related Art Water deaeration methods are roughly classified into chemical deaeration methods and mechanical deaeration methods. The former is a method in which a chemical such as sodium sulfite or hydrazine is added to water and reacted with oxygen in the water to reduce dissolved oxygen. 2Na ₂ SO ₃ + O ₂ = 2Na ₂
Oxygen in water is removed by using a reaction such as SO ₄ , H ₂ N.NH ₃ + O ₂ = 2H ₂ O + N ₂ . In the latter mechanical deaeration method, dissolved oxygen is extracted to the outside by applying pressure or pressure reduction operation to water.
By the way, in the above chemical degassing method, (a) the degassing rate greatly varies depending on the reaction temperature, (b) the drug is strongly reducing and is not easy to handle, and (c) the degassing due to the depletion of the drug. There are drawbacks such as easy occurrence of defects and (d) high processing cost due to expensive chemicals. Further, the latter mechanical degassing method also has a problem that the degassing apparatus becomes large due to the low degassing treatment capacity per unit volume of the apparatus, resulting in a high equipment cost.

On the other hand, in order to solve the problem as described above, a deaerator using a so-called membrane module as shown in FIG. 9 has been developed. In the membrane module type deaerator, the raw water W heated in the tank A by the water feed pump B is pumped into the hollow fiber of the membrane module C, and the outer space of the hollow fiber membrane is depressurized by the vacuum pump D. Thereby, oxygen and the like in water is extracted to the outside through the hollow fiber membrane. Further, the degassed water W ₀ treated through the membrane module C is temporarily stored in the degassing tank E, and thereafter, a required amount of degassed water W ₀ is generated by the water supply pump P in accordance with the operating condition of the boiler F. It will be supplied as water supply. In FIG. 9, H is a steam heater, T is a temperature sensor, and Q is a filter.

The membrane type deaerator has an excellent practical utility because it can be downsized as compared with the conventional mechanical deaerator. However, there still remain many problems to be improved in the membrane type deaerator. The first problem is that the facility utilization rate of the membrane module is extremely poor. That is, generally, in a boiler facility or the like, it is usual to install a deaerator having a deaerating capacity commensurate with the maximum capacity of the boiler. However, it is rare that the boiler equipment is operated at full load, and it is normal to operate it at a load of about 50 to 70%. As a result, when the boiler make-up water is small, the operation of the membrane deaerator is temporarily stopped to operate the membrane module C in a so-called intermittent operation, and the equipment utilization rate as the deaerator decreases. In addition to this, various inconveniences occur, such as shortening the mechanical life of the hollow system.

The second problem is that it is difficult to reduce the size of the deaerator to a large extent and the dissolved oxygen concentration in water tends to be unstable. In the conventional membrane-type deaerator, the raw water tank A and the deaerator tank E are completely separated by the membrane module C as shown in FIG. 9, and the liquid surfaces of both tanks A and E are separated. Each is individually controlled by the electrode rod type liquid level control method. Therefore, the capacities of the raw water tank A and the degassed water tank E inevitably increase, and a plurality of liquid level control devices are required, which makes it difficult to reduce the equipment cost. Further, since the raw water W and the degassed water W ₀ are supplied intermittently, the raw water temperature in the raw water tank A fluctuates greatly, and the membrane module C is also degassed at the start-up in the intermittent operation. Qi characteristics fluctuate. Apart from this, if the residence time in the degassed water tank E becomes long (when the load on the boiler equipment is light, when the boiler is temporarily stopped), it is easy to take in dissolved oxygen in the atmosphere,
There is no reliable way to remove dissolved oxygen once dissolved.
Moreover, in the conventional membrane deaerator, the raw water W and the deaerated water W
_{At the time} of intermittent replenishment, water is dropped directly into the tank, so bubbles may be caught in the water at the time of replenishment, and there is a problem that the dissolved oxygen concentration is likely to rise.

[0006] The third problem is that the vacuum pump D consumes a large amount of water sealing water. The vacuum pump D for evacuating the outer space of the hollow fiber membrane of the membrane module C consumes a considerable amount of water sealing water. However, in the conventional membrane deaerator, all the water sealing water is discarded to the outside,
The consumption of raw water W is significantly increased.

[0007]

SUMMARY OF THE INVENTION The present invention has the above-mentioned problems in the conventional membrane module type deaeration system, that is, the membrane module is intermittently operated according to the boiler load.
Causing a reduction in equipment utilization rate and mechanical life,
By requiring a relatively large capacity raw water tank and degassed water tank, and intermittent supply of raw water and degassed water,
Dissolved oxygen concentration may change in the degassed water, susceptible to entrainment of the raw water bubble, at the boiler starts, the high dissolved oxygen concentration D _o water is supplied to the boiler, the raw water by the operation of the vacuum pump This is to solve the problem of increasing the consumption of water, etc., and to operate the membrane module continuously regardless of the boiler load, and to connect the raw water tank and the degassed water tank organically, and By circulating deaerated water in the order of membrane module-deaerated water tank-raw water tank, it is possible to significantly reduce the size of the deaerator and reduce the equipment cost and operating cost. It is intended to provide a membrane-type deaerator capable of smoothly obtaining low deaerated water and a method for deaerating raw water.

[0008]

SUMMARY OF THE INVENTION The invention of the device of the present invention is to provide raw water W.
A raw water tank 1 equipped with a liquid level control device for replenishing the liquid surface to keep the liquid surface L ₁ at a predetermined position and an automatic heating device for heating the raw water W to a predetermined temperature; Membrane module 3 for degassing water; Degassing water tank 2 for storing degassed water W ₀ that has been degassed; Raw water tank 1
And a degassed water tank 2, and a circulation pipe line 15 having a water level difference actuating valve 16 that opens on the degassed water tank 2 side when the water level difference H between the tanks 1 and 2 exceeds a predetermined value. When;
The basic structure is a water supply pump 6 that continuously feeds the raw water W in the raw water tank 1 at a predetermined flow rate to the membrane module 3. The water supply pump 6 is continuously operated to operate the deaerated water tank 2 inside. The surplus degassed water W _r is recirculated to the raw water tank 1 through the circulation pipe 15.

Further, in the method invention of the present case, the raw water W is pressure-fed from the raw water tank 1 to the membrane module 3 by the water feed pump 6.
In the membrane type deaerator in which the deaerated water W ₀ that has been deaerated is stored in the deaerated water tank 2 and the deaerated water W ₀ is supplied to a desired location by the water supply pump 10. 6 is continuously operated at a predetermined water supply flow rate, and the degassed water tank 2 and the raw water tank 1 are connected to each other via a liquid level difference actuating valve 16 that opens when the liquid level difference H between them exceeds a predetermined value. Then, the excess deaerated water W _r in the deaerated water tank 2 is supplied to the liquid level differential operation valve 1
It is the basic constitution of the invention that the raw water tank 1 is circulated through the tank 6.

[0010]

The raw water W in the raw water tank 1 is controlled by the liquid level control device and heated to a constant temperature by the automatic heating device. The heated raw water W is continuously pumped to the membrane module 3 at a predetermined flow rate by the water pump 6.
The treated deaerated water W ₀ is supplied to the deaerated water tank 2.
If the supply of deaerated water W _{0 to} the outside is small, the deaerated water tank 2
The liquid level L ₀ is elevated, the liquid level L ₁ and the liquid level difference H of the raw water tank 1 exceeds a predetermined value, the water level difference operation valve 16 is opened, the deaerated water W _r is the raw water tank 1 Is recirculated. In this way, the deaerated water tank 2-raw water tank 1-water pump 6
-When water is refluxed through the membrane module 3 and the amount of degassed water W ₀ supplied to the outside is small, degassed water having a lower dissolved oxygen concentration is obtained. The mixed fluid discharged from the liquid gas outlet of the vacuum pump 5 is sent into the liquid gas separator 20, and the recovered raw water is returned into the raw water tank 1. Furthermore, when the liquid level L ₀ in the degassed water tank 2 drops below a certain level, the bypass water level difference actuating valve 18 is opened, and the raw water W passes through the bypass line 17 and the degassed water tank 2
It can be transferred to the inside.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall system diagram of a membrane type deaerator according to the present invention. In FIG. 1, 1 is a raw water tank, 2 is a deaerated water tank, 3 is a membrane module, 4 is a filter, 5 is a vacuum pump (water sealing water pump), 6 is a water pump, 7 is a constant flow valve, 8
Is a filter, 9 is a flow switch, 10 is a boiler feed water pump, 11 is a boiler, 12 is a temperature sensor, 13 is a steam heater, 14 is a steam solenoid valve, 15 is a circulation pipeline, 16 is a circulating water level difference actuating valve, 17 Is a bypass line, 18 is a bypass water level difference actuating valve, 19 is an overflow line, 20 is a liquid gas separator, 21 is a raw water supply control valve, 22-29 are lines,
W is raw water, W ₀ is degassed water, S is steam, G is gas,
The temperature sensor 12, the steam heater 13, and the steam solenoid valve 14
The automatic heating device T is operated by the
The liquid level control devices Y are formed by the respective numbers 1.

First, the outline of the construction and operation of the deaerator according to the present invention will be described with reference to FIG. The raw water W (softened water in the case of boiler feed water) is supplied to the raw water tank 1 through the raw water supply control valve 21 after removing solid matters through the filter 4, and the raw water supply control valve 21 causes the liquid surface to have a constant liquid level. It is temporarily stored in the raw water tank 1 while being held at L ₁ . The boiler 11 is connected to the steam heater 13 in the raw water tank 1.
Steam is blown in from, the temperature is detected by the temperature sensor 12, and the amount of steam is adjusted to reach a predetermined temperature. The heated raw water W is supplied to the membrane module 3 through the water pump 6, the constant flow valve 7, and the filter 8. The membrane module 3 is divided into two chambers across the membrane, and the heated raw water W flows through one side of the membrane. The other side of the membrane is vacuumed by the vacuum pump 5, whereby the dissolved gas G in the heated raw water W is permeated through the membrane and degassed. Further, part of the raw water W is supplied to the vacuum pump 5 as water sealing water W _s ,
In addition, the water-sealing water W _s after use is returned to the raw water tank 1 through the liquid gas separator 20 so that the raw water W is effectively used. The deaerated water W ₀ is passed through the pipe 25 to the deaerated water tank 2
And is supplied to the boiler 11 by the water supply pump 10 via the pipe 23.

The water supply pump 6 is continuously operated irrespective of the load on the boiler 11 and sends a predetermined constant flow rate of water W _p to the membrane module 3. as a result,
From the membrane module 3, a constant flow of degassed water W ₀ is sent to the degassed water tank 2. In this state, the boiler 11
Is a light load and the boiler water supply is small, the liquid level L ₀ of the deaeration water tank 2 rises, and the raw water tank 1 and the deaeration water tank 2
The water level difference H between them becomes large. When the water level difference H exceeds a certain value, the circulating water level difference actuating valve 16 is opened and the degassed water W _r
Is circulated into the raw water tank 1. That is, the degassed water W _r circulates in the order of the water pump 6, the membrane module 3, the degassed water tank 2, and the raw water tank 1. On the contrary, the membrane module 3
When the liquid level L ₀ of the degassed water tank 2 becomes equal to or less than the set value due to clogging of the water, the bypass water level difference actuating valve 18
Is opened, and the raw water W in the raw water tank 1 is transferred into the degassed water tank 2 through the bypass line 17. As a result, the shortage of the deaerated water W ₀ can be temporarily replenished with the raw water W.

The membrane module 3 is a so-called hollow fiber membrane module. The membrane module 3
As shown in FIGS. 2 and 3, the hollow fiber group 3b is filled in a casing 3a provided with a raw water inlet 3d, a degassed water outlet 3e, and a gas outlet 3f. The upper and lower ends of the hollow fiber group 3b are sequentially sealed with an adhesive 3c, whereby a vacuum portion 3g and a water passage portion 3h are formed with the hollow fiber membrane 3b 'sandwiched therebetween, and each vacuum portion 3g. Is communicated with the gas outlet 3f of the casing 3a. The heated raw water W enters the casing 3a through the inlet 3d, passes through the water passage portion 3h of the hollow fiber group 3b, and is discharged outside through the outlet 3e. On the other hand, the vacuum portion 3g of the hollow fiber group 3b is evacuated by the vacuum pump 5 through the gas discharge port 3f, and the gas G dissolved in the water flows through the hollow fiber membrane 3b 'while the heated raw water W is flowing through the hollow fiber. Degassing is performed by passing through and moving to the vacuum side. The structure of the membrane module 3 is not limited to the hollow fiber membrane, and may be a flat membrane or a flat membrane wound in a spiral shape, or the same effect can be obtained with a tube type membrane.

Next, a degassing system comprising the raw water tank 1, the degassed water tank 2 and the membrane module 3 which constitutes the main part of the present invention will be described with reference to FIG. The raw water tank 1 includes a partition wall 1a and a partition wall 1b, and the inside of the raw water tank 1 includes a first chamber R ₁ and a second chamber R ₂ ,
It is divided into 3 rooms, the 3rd room R ₃ , and each room has a water passage hole 1g.
And 1h are in communication with each other. Further, the first chamber R ₁ of the raw water tank 1 is communicated through the liquid-gas separator 20 and the water passage holes 1i which will be described later, through further the second chamber R ₂ is bypass conduit 17, also the third chamber R ₃ are connected to the degassed water tank 2 through the circulation line 15. The water passage hole 1g is provided at a position slightly lower than the water passage hole 1h.

The first chamber R ₁ forms a heating chamber for the replenished raw water W, and an automatic heating device T including a steam heater 13 and a temperature sensor 12 and a liquid level control device Y are provided inside the first chamber R _1.
A float-type raw water supply control valve 21 for forming the above is provided respectively. The temperature sensor 12 is arranged near the water passage hole 1g. The raw water replenishment control valve 21 has a valve mechanism portion 21a disposed above the liquid level L ₁ of the first chamber R _{1 and} a float portion 21b disposed above the liquid level L ₁ of the second chamber R _2. Further, the valve discharge port 21c is arranged below the liquid surface of the first chamber R ₁ . Further, although the liquid level control device Y of the raw water tank 1 is configured by the float type control valve 21 in this embodiment, it may be a normal electrode rod type liquid level control device Y. The second chamber R ₂ forms a liquid level detecting chamber for the raw water W, and is provided with one end of a bypass pipe line 17 described later and the float portion 21b. The third chamber R ₃ forms a mixing chamber of raw water W and deaerated water W ₀ in the deaerated water tank 2 described later, and one end of the circulation conduit 15 and one end of the conduit 24 are provided. ing.

The raw water W is first passed through the raw water supply control valve 21.
It is supplied into the raw water of the chamber R ₁ , and the liquid level L ₁ in the tank is controlled to a predetermined liquid level by the float 21b. The supplementary raw water W ₁ is discharged from the discharge port 21c located below the liquid surface.
Since it is discharged from the tank into the tank, air bubbles are not entrained in the water due to the discharge of raw water. Further, since the provided float portion 21b of the raw water supply control valve 21 into the second chamber R _2, also not reach directly affect the float portion 21b occurs the wave in the liquid level L ₁ during replenishment of the raw water W, very Accurate liquid level control is possible. The raw water W in the first chamber R ₁ is controlled by the temperature sensor 12 while controlling the inflow steam amount S, and the steam heater 13
And is kept at a predetermined temperature. By heating the raw water W by the steam heater 13, the dissolved oxygen concentration D ₀
Is reduced. Further, since the water passage holes 1g is provided at lower position than the water-passing hole 1h, even at the time of the first chamber lowest level of R ₁ and the second chamber R _2, a temperature sensor 12 is always in the raw water W Since it is located, more accurate temperature control becomes possible. The raw water W heated to the predetermined temperature is the partition wall 1
The third chamber R while the bubbles are restricted from flowing out by a and 1b.
Degassing water W ₀ is supplied to the degassed water tank 2 by flowing into ₃ and then being pressure-fed to the membrane module 3 through the conduit 24.

The degassed water tank 2 is provided adjacent to the raw water tank 1, and the capacity of the dewatered water tank 2 when the water is full is selected to exceed the total amount of water held in the can of the boiler 11. The degassed water tank 2 and the third chamber R ₃ of the raw water tank 1 are communicated with each other by a circulation pipe line 15 having a circulation water level operation valve 16. When the water level difference H between the liquid level L ₁ of the liquid surface L ₀ of degassed water tank 2 raw water tank 1 is equal to or greater than the set value, degassed water by the water level difference operated valve 16 is opened in degassed water tank 2 W _r is recirculated into the third chamber R ₃ of the raw water tank 1. The degassed water tank 2 and the second chamber R ₂ of the raw water tank 1 are connected by a bypass pipe 17 having a bypass water level difference actuating valve 18, and the liquid level L ₀ in the degassed water tank 2 is connected. Is below a set value, the bypass water level difference actuating valve 18 is opened, and the raw water W in the second chamber R ₂ enters the degassed water tank 2 by-pass pipe 1
Transported through 7. Further, when the first chamber R ₁ of degassed water tank 2 and the raw water tank 1 is communicated with an overflow pipe 19, the water level difference actuated valve 16 or the like is failure,
The degassed water W ₀ overflows into the first chamber R ₁ .

The water level difference actuating valve 16 is composed of a valve box 16a having a valve seat, a valve body 16b and the like. The water level difference (head) H is determined by the weight of the valve body 16b and the area of the contact surface. When the water head is determined by, the valve begins to open. Further, in the actuating valve 16, the lift amount and the transfer amount per unit time are proportional to the constant lift of the valve body 16b, and when the valve body 16b reaches the constant lift, the transfer amount is proportional to the water level difference H. Finally, the water level L ₀ of the degassed water tank 2 rises above the water level L _{1 of the} raw water tank 1 only by the water head of the flow path resistance of the circulation pipe line 15 including the operation valve 16. That is, the water level difference H between the degassed water tank 2 and the raw water tank 1 is determined by the correlation between the size of the selected actuating valve 16 and the amount of transferred water per unit time. Since the water level difference actuating valve 16 has a so-called check valve function, even if the liquid level L ₀ of the degassing water tank 2 becomes lower than the liquid level L ₁ of the raw water tank 1, the raw water W Does not flow back through the circulation line 15.

The bypass water level difference actuating valve 18 is composed of a valve box 18a having a valve seat, a valve body 18b, a back pressure adjusting spring 18c and the like. In this embodiment, when the flow switch 9 is activated and the water pump 6 is stopped, when the liquid level L ₀ of the degassed water tank 2 is lowered to near the tank bottom surface, the operation valve 18 is opened. It is set.

The capacity of the water supply pump 6 is selected to be about 1 to 2 times the rated evaporation amount of the boiler 11, and a constant flow rate of raw water W set by the constant flow rate valve 7 is sent to the membrane module 3. .. Further, the capacity of the degassed water tank 2 is selected to be larger than the amount of water held in the boiler 11 of the boiler 11 as described above. As a result, the degassed water in the degassed water tank 2 becomes insufficient due to the boiler water supply by the boiler water supply pump 10 not only during the initial water supply at the start of the boiler operation but also during the operation under the maximum load condition. Does not happen. Now, when the load on the boiler 11 is reduced and the boiler water supply amount is reduced, the liquid level L ₀ in the degassed water tank 2 rises. When the liquid level difference H between the raw water tank 1 and the degassed water tank 2 reaches the set value, the water level difference actuating valve 16 is opened and the degassed water W _r is passed through the circulation line 15.
Is returned into the third chamber R ₃ of the raw water tank 1. That is, the less water is supplied to the boiler 11, the lower the liquid level L of the degassed water tank 2.
₀ increases rapidly, and the larger the generated water level difference H is, the larger amount of degassed water W _r is returned to the raw water tank 1 through the circulation line 15, and the water level difference H fluctuates within a certain range. ..

The circulating water level difference actuating valve 16 is operated by the deaerated water W _0.
Since it is provided below the liquid surface of the degassed water W _r, no bubbles are taken into the water surface due to the transfer of the degassed water W _r.
The dissolved oxygen concentration D ₀ never rises due to the circulation of _r . Further, since the return port of the circulation pipe 15 is located lower than the raw water inlet port 1h to the third chamber R ₃ of the raw water tank 1, the return amount of the degassed water W ₀ is preferentially absorbed by the water pump 6. As a result, the dissolved oxygen concentration of the degassed water W ₀ in the degassed water tank 2 can be efficiently reduced. Further, when the liquid level L ₀ in the degassed water tank 2 falls below a set value due to a failure of the water pump 6 or the membrane module 3, the bypass water level difference actuating valve 18 is opened, and the raw water W in the raw water tank 1 is opened. Is supplied to the deaerated water tank 2. As a result, even if the membrane module 3 is clogged, the boiler 11 can be continuously operated as necessary.

The liquid-gas separator 20 is formed in a double pipe structure of an outer pipe 20a and an inner pipe 20b, and the outer pipe 20a.
Is communicated with the bottom of the first chamber of the raw water tank 1 through the water passage hole 1i. Also, the upper end of the outer tube 20a has a reverse U shape.
It is distorted in shape, the distortion inner surface H ₃ raw water tank 1
It has been lifted slightly above the liquid surface of. Outer tube 20a
The upper end face opening 20d of the is facing downward. Furthermore the upper end opening 20c of the inner tube 20b is lifted slightly above the H _3.

[0024] When the vacuum pump 5 is operated, to the conduit 29, a mixture X with water seal water W _s from gas G and the flow path 28 by suction through the conduit 26 is discharged. The mixture X is introduced into the inner pipe 20b, discharged from the tip opening 20c into the outer pipe 20a, and separated into gas G and raw water W.
The separated raw water W drops into the outer pipe 20a and is collected in the raw water tank 1, and the separated gas G is discharged to the outside through the tip opening 20d of the outer pipe 20a.
For example, if the capacity of the boiler 11 is 1 Ton / h, 10
If it is operated with a light load of 100%, the amount of makeup water to the raw water tank 1 is 1000 kg × 0.1 = 100 kg / h. On the other hand, the water sealing water W _s for the vacuum pump is generally 3 l /
Since it is about min (180 kg / h), 180 kg / h of water sealing water W _{s in} the liquid gas separator 20 is stored in the raw water tank 1.
Be recovered to. As a result, 180-100 = 80 kg /
the liquid level L ₁ of the raw water tank 1 at a rate of h is raised, the distal end opening of the outer tube 20a when the liquid level L ₁ exceeds the head H ₃ 20
It will be discharged from d. That is, the boiler 11
During light load operation, only the amount of the water sealing water W _s commensurate with the load is collected, and the consumption of heating steam energy due to the collection of unnecessary water sealing water W _s is reduced.

In the liquid-gas separator 20, when the separated water-sealed water W _s falls on the water surface, some air bubbles are taken in below the water surface. However, this is captured bubbles completely reversed within this height H ₃ in order to have a separator 20 considerable height H _3, which it is completely free to brought into the raw water W through water passage holes 1i. Further, since the separated gas G is directly discharged to the outside through the opening 20d, there is no possibility of being brought into the raw water W. Furthermore,
The recovered water sealing water W _s is heated by the heat recovery in the vacuum pump 5, and the heat recovery is also performed. In addition, since the overflow port of the entire system including the degassed water tank 2 and the raw water tank 1 is the tip opening 20d of the outer pipe 20a of the liquid gas separator 20, the degassed water W
The contact area between ₀ and the outside air becomes extremely small, and the increase in dissolved oxygen due to contact with the outside air can be prevented.

In the embodiment of the present invention shown in FIG. 4, the degassed water tank 2 is integrally provided adjacent to the third chamber R ₃ of the raw water tank 1 so that both side walls are common. Although it is configured, it goes without saying that both tanks 1 and 2 may be independent tanks. Further, as shown in FIGS. 5 to 8, it goes without saying that the raw water tank 1 and the degassed water tank 2 may be arranged in parallel to form an integral type.

[0027]

In the present invention, the water feed pump 6 for feeding the raw water W to the membrane module 3 is continuously operated regardless of the supply amount of degassed water to the outside, and the surplus degassed water W _r is at the water level. The raw water tank 1 is circulated through the differential operation valve 16. As a result, the smaller the supply amount of deaerated water W ₀ to the outside, the larger the return amount of the deaerated water W _r to the raw water tank 1, and the ratio of the deaerated water amount to the total supplied water amount W _p by the water supply pump 6. Increasing, the dissolved oxygen concentration decreases significantly. Further, the water supply pump 6 is always continuously operated, and degassing is not stopped by the on-off of the water supply pump 10. As a result, the operation of the membrane module 3 can be performed extremely stably, the equipment capacity can be fully utilized, and highly degassed degassed water can be obtained.
Further, the supply amount of the raw water W is adjusted via the float portion 21b of the raw water supply control valve 21 by the circulation of the deaerated water W ₀ ,
The supply of raw water commensurate with the boiler load can be performed smoothly without using electrical control, and unlike the intermittent supply of raw water in the case of electrode surface level control, the amount of degassed water W _r returned is insufficient. Since only the raw water W for a minute is continuously replenished, the fluctuation of the dissolved oxygen ratio in the third chamber R ₃ of the raw water tank 1 is significantly reduced. In addition, the liquid gas separator 20 collects the water sealing water W _s of the vacuum pump 5 and limits the amount of the water sealing water W _s required in the raw water tank 1 to automatically discharge the excess amount to the outside. Raw water W because it is configured
Not only can the running cost be reduced due to the reduction of the above, but the thermal efficiency can also be improved. The present invention has excellent practical utility as described above.

[Brief description of drawings]

FIG. 1 is an overall system diagram of a membrane degassing apparatus according to the present invention.

FIG. 2 is a schematic partial cross-sectional view of a membrane module.

FIG. 3 is an enlarged view of an X portion of FIG.

FIG. 4 is an enlarged explanatory view around a raw water tank and a degassed water tank used in the present invention.

FIG. 5 is a plan view showing another combination example of the raw water tank and the degassed water tank.

FIG. 6 is a sectional view taken along line XX in FIG.

FIG. 7 is a sectional view taken along line YY in FIG.

8 is a sectional view taken along line ZZ in FIG.

FIG. 9 is an overall system diagram of a conventional membrane deaerator.

[Explanation of sign]

1 Raw water tank 16a Valve box 1a Partition wall 16b Valve body 1b Partition wall 17 Bypass pipeline 1g Water passage hole 18 Water level difference actuating valve for bypass 1h Water passage hole 18a Valve box 1i Water passage hole 18b Valve body R ₁ First chamber 18c Spring R ₂ Second chamber 19 Overflow conduit R ₃ Third chamber 20 Liquid gas separator 2 Degassed water tank 20a Outer pipe 3 Membrane module 20b Inner pipe 3a Casing 20c Upper end opening 3b Hollow fiber group 20d Upper end opening 3b 'Hollow fiber membrane 21 Raw Water Supply Control Valve 3c Adhesive 21a Valve Mechanism 3d Raw Water Inlet 21b Float 3e Degassed Water Outlet 21c Discharge Outlet 3f Gas Outlet 22-29 Pipeline 3g Vacuum Part T Automatic Heating Device 3h Water Passing Y Liquid feed water 7 to the surface control unit 4 filter W raw water 5 vacuum pumps W ₀ degassed water 6 water pump W _p membrane module constant flow valve W _b Boi Water 8 filter W _s Mizufusui 9 flow switch W _r circulating degassed water 10 boiler feedwater pump S steam 11 boiler G mixture 13 steam heater L ₁ raw water tank degassing gas 12 temperature sensor X degassed gas and water sealing water Liquid level 14 Steam solenoid valve L ₀ Liquid level of degassed water tank 15 Circulation line H Liquid level difference (L ₀ −L) 16 Circulation water level difference actuating valve H ₃ Outer pipe 2
Height of the upper curved portion of 0a

Claims (6)

[Claims] 1. A liquid level control device (Y) for replenishing the raw water (W) to hold the liquid level (L ₁ ) at a predetermined position, and an automatic heating device (T) for heating the raw water (W) to a predetermined temperature. A raw water tank (1) provided; a membrane module (3) for degassing the raw water (W) using a vacuum from a vacuum pump (5); and storing degassed degassed water (W ₀ ). The deaerated water tank (2) for communicating with the raw water tank (1) and the deaerated water tank (2), and between the tanks (1) and (2) on the deaerated water tank (2) side. Circulation conduit (15) having a water level difference actuating valve (16) that opens when the water level difference (H) exceeds a predetermined value
And; a water feed pump (6) for continuously feeding the raw water (W _p ) in the raw water tank (1) to the membrane module (3) at a predetermined flow rate.
And continuously operating the water pump (6),
A membrane-type deaerator characterized in that excess deaerated water (W _r ) in the deaerated water tank (2) is circulated to the raw water tank (1) through the circulation pipe (15). 2. A liquid level control device (Y) for replenishing the raw water (W) to hold the liquid level (L ₁ ) at a predetermined position and an automatic heating device (T) for heating the raw water (W) to a predetermined temperature. A raw water tank (1) provided; a membrane module (3) for degassing the raw water (W) using a vacuum from a vacuum pump (5); and storing degassed degassed water (W ₀ ). The deaerated water tank (2) for communicating with the raw water tank (1) and the deaerated water tank (2), and between the tanks (1) and (2) on the deaerated water tank (2) side. Circulation conduit (15) having a water level difference actuating valve (16) that opens when the water level difference (H) exceeds a predetermined value
And; a water feed pump (6) for continuously feeding the raw water (W _p ) in the raw water tank (1) to the membrane module (3) at a predetermined flow rate.
And; formed by a double pipe having an open upper end that is slightly higher than the liquid level (L ₁ ) of the raw water tank (1), and connects the lower end of the outer pipe (20a) with the inside of the raw water tank (1). It comprises a liquid gas separator (20) adapted to connect the liquid gas discharge port of the vacuum pump (5) to the lower end of the inner pipe (20b), and continuously operates the water feed pump (6). Membrane-type deaerator characterized by circulating excess deaerated water (W _r ) into the raw water tank (1) and collecting water sealing water from a vacuum pump. 3. A raw water tank (1) and a degassed water tank (2)
To the degassed water tank (2) side, the valve opens when the liquid level (L ₀ ) of the degassed water tank (2) drops below a predetermined value, and the raw water (W) in the raw water tank (1) (W) is opened. _The bypass line (17) having a water level difference actuating valve for bypass (18) for advancing _p ) into the degassed water tank (2) is communicated with the degassing water tank (2) according to claim (1) or claim (2). Membrane-type deaerator. 4. The raw water tank (1) is provided with a water passage hole (1 g),
It is divided into three chambers by partition walls (1a) and (1b) having (1h), an automatic heating device (T) is arranged in the first chamber (R ₁ ) for supplying raw water (W), and a water pump ( 6) Into the third chamber (R ₃ ) supplying raw water (W _p ) to the circulation line (1
5. The structure according to claim 1 or 2, wherein one end of 5) is opened.
The membrane-type deaerator described in 1. 5. A raw water tank (1) through hole (1 g),
It is divided into three chambers by partition walls (1a) and (1b) having (1h), the liquid level control device (Y) is a float type raw water supply control valve (21), and the raw water (W) is stored in the first chamber ( R
Supply below the liquid level of ₁ ) and at the same time supply control valve (2)
The membrane deaerator according to claim 1 or 2, wherein the float ball (21b) of 1) is arranged on the liquid surface of the second chamber (R ₂ ). 6. A water feed pump (6) from a raw water tank (1)
The raw water (W) is pressure-fed to the membrane module (3) by the above, the deaerated water (W ₀ ) which has been deaerated is stored in the deaerated water tank (2), and the deaerated water (W) is supplied by the water supply pump (10). ₀ ) is supplied to a desired location in a membrane type deaerator,
A liquid that continuously operates the water supply pump (6) at a predetermined water supply flow rate and opens when the liquid level difference (H) between the degassed water tank (2) and the raw water tank (1) exceeds a predetermined value. A surface difference operation valve (16) is provided for communication, and excess deaerated water (W _r ) in the deaeration water tank (2) is passed through the liquid surface difference operation valve (16) to the raw water tank (1). A method for degassing raw water, which is characterized in that it is circulated.