JP3509846B2 - Power plant heater drain water treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a power plantToWhiskers
-Regarding the method of treating drain water, especially in power plants
The heater drain water for removing iron from the heater drain water
Regarding the processing method. The method of the present invention provides
Power plant (abbreviated as “PWR”), boiling water nuclear power plant (abbreviated
And “BWR”) and thermal power plants.
-Removal of fine iron oxide particles contained in water
It can be used particularly advantageously in such cases. [0002] 2. Description of the Related Art For example, in a PWR, a turbine drive
Two steam generators (SG, steamgenerator) that produce steam
Metal oxide containing iron oxide fine particles as the main component in the next vessel
And other impurities are brought with the water supply. And departure
During powering, these impurities are transferred to the steam generator.
Slowly adheres to the outer surface of the heat tube, and the adhered matter generates steam
Heat transfer efficiency from the primary side of the vessel to the secondary side water supply is reduced.
In addition, these impurities gradually become available during the circulation of the water supply.
Concentration and increase, there is concern about the formation of an impurity concentration environment, etc.
Therefore, the impurity concentration in the secondary feedwater to the steam generator has been reduced.
Various measures have been considered in the past. [0003] As in the case of PWR, thermal power plants
But the above metal acids contained in the water supply to the boiler
Impurities such as chlorides gradually adhere to the inner surface of the heat transfer tube of the boiler
However, this deposit increases the differential pressure of the boiler.
In addition, various measures have been studied to reduce this differential pressure rise.
Have been. [0004] SUMMARY OF THE INVENTION Steam generation
The main component is iron oxide fine particles brought into vessels and boilers.
Focus on iron removal methods to effectively remove impurities
Various investigations have been made on the method of removing impurities
Despite the fact, there is still no established technology
is the current situation. Therefore, supply to steam generators and boilers
Introducing such impurities brought along with water
Considering the source, the amount brought in from the condensate system
It is roughly divided into the amount brought in from various heater drain water systems.
You can see that However, the condensing system is generally installed before the condensing water.
Filter and condensate desalination unit or condensate desalination unit alone
A condensate purification system is installed, which generates steam
Of condensate from condensate system in water supply to vessels and boilers
The amount of insertion is relatively small. Therefore, a steam generator or a boiler
To reduce the concentration of impurities in the feedwater to the
Brought in from various heater drain systems after the water purification system
It is considered effective to reduce the amount of impurities
You. [0005] Main impurities in power plant heater drain water system
The form of the iron-based impurity is described below. Heated
Len water system is deoxygenated to prevent corrosion of equipment and piping
The treatment is performed, and the dissolved oxygen concentration is extremely low as several ppb.
Although it is in a state that does not contain extreme oxygen, such extreme
Even under low dissolved oxygen concentration conditions,
This produces a thin coating of iron oxide (magnetite). And an example
For example, in the PWR, it occurs after the steam generator.
Iron oxide constantly formed on equipment and piping by steam
Thin film is removed. This phenomenon is called erosion (er
osion) This is called a phenomenon. Like this constantly
Condensation occurs because the steam removes a thin film of iron oxide
Iron oxide particles finer than the iron oxide particles contained in
Estimated to be contained in the heater drain water
Is done. Iron oxide particles in condensate and heater drain water
One example of the fineness of the diameter is the pore size of a microfiltration membrane.
0.22 μm Millipore filter [Millipore (US
Condensate and heater in thermal power plants
Removal of iron oxide particles from drain water and from
Comparing with iron rate, condensate shows 94% iron removal rate
In the case of heater drain water, the iron removal rate is 53%.
Was. From this, iron oxide particles in the heater drain water
Recovers extremely fine particles having a particle size of about 0.22 μm or less.
It can be seen that it is contained much more than in the case of water. [0007] The treated water in the power plant is adjusted for pH.
To prevent elution of iron ions from piping etc.
Of iron in the heater drain water as ions
Is low, and the form of iron to be removed is iron oxide fine particles.
Therefore, it is necessary to remove the iron oxide fine particles.
was there. [0008] However, in the heater drain water, the above described
Iron oxide is very fine particles due to erosion
In a generally used pore size filtration membrane
Has the problem that the iron removal rate is not stable. [0009] Such iron oxide fine particles are separated from the heater drain water.
A method to effectively remove impurities mainly composed of particles
For example, filters such as electromagnetic filters and metal filters
Although the use of luter has been considered,
Iron oxide particles, the main component of impurities, are extremely
And fine particles, the
Pure substance removal performance is unstable and has reached the stage of practical use
Absent. In other words, at present, there is no
Generates steam without removing impurities
Into the vessel or boiler. In addition, fine particles are contained in various filters.
Polymer hollow fiber membrane filter
There are membrane filters such as
If used as is, the above electromagnetic filters and metal filters
As with filters such as filters, heater drains
Removal performance of impurities mainly composed of iron oxide fine particles from water
(Especially iron removal performance) is unstable.
Therefore, before passing the heater drain water, γ-Fe₂O₃or
Is Fe₃O₄Particles adhere to the filtration surface of the membrane filter in advance
To form a pre-coated film of the particles,
Performance can be improved and membrane filters can be applied
You. In other words, before passing the heater drain water,
And specific iron oxide (γ-Fe₂O₃Or Fe₃O₄)grain
A certain amount [for example, 20 to 100 g-Fe / m²
("G-Fe" means Fe conversion)]
Pre-coated on the filtration surface of
Forming, the iron removal performance is stabilized and the membrane filter
It is known to be usable. [0011] The precoat of which practicality has been confirmed
The type of the agent is limited (the above-mentioned γ-Fe₂O₃With particles
Fe₃O₄Particles), the selection range is narrow, and
High iron removal performance of the filter
Stabilization and improvement of its practicality are desired. The present invention has been made in view of the above situation.
Is included in the heater drain water at the power plant.
Iron oxide particles are removed stably and reliably.
Oxide fine particles to steam generator or boiler of power plant
Power plants that can effectively prevent
To provide a method for treating heater drain water
It is. [0013] Means for Solving the Problems The present inventors have developed various kinds of particles.
Is used as a pre-coating agent for filters,
Of iron oxide particles in the heater drain water
As a result of various studies on the removal effect of
Particles having a specific pore radius and a specific specific surface
Using particles with a volume as a precoat agent for filters
Found that high iron removal performance can be stabilized by
Ming completed. That is, the present invention provides a power plant
Iron removal from heater drain water in Japan
Used as a pre-coating agent for filters to improve the effect
The pore radius at the peak position of the pore radius distribution is 0.2 μm
Below, the specific surface area is 5m²/ G particles or more
A method for treating drainage water of a power plant heater
To provide. The use of such a pre-coating agent makes it possible to remove iron.
It is not clear why performance improves
However, it is considered as follows. In the heater drain water,
In the above example, iron oxide fine particles with a particle size of about 0.22 μm or less
Particles are contained in about a half of the total iron oxide particles.
It contains a large amount of fine iron oxide fine particles. Such a pole
In addition, fine particles can be used by themselves even in membrane filters.
Penetrates through the pores of the membrane and obtains sufficient iron removal performance.
It is considered impossible. The above-mentioned iron oxide (γ-F
e₂O₃Or Fe₃O₄) When using particles, Prico
The iron removal performance of the membrane filter
Is sufficient, but the passage of the heater drain water
Both tend to decline gradually. From this,
-Removal (fine iron removal) of fine iron oxide particles in
Not only physical filtration mechanism by filter, but also
Mechanism of Electrochemical Filtration of Adsorbed Iron Oxide Particles
Also seem to be heavily involved. Accordingly, the iron oxide particles are filtered through a membrane filter.
Pre-coating on the surface improves iron removal performance
The heater inside the pores of the pre-coated iron oxide particles
The extremely fine iron oxide particles in the drain water are adsorbed and trapped.
It is thought to be due to being caught. Also, the iron removal performance is low after the passage of water.
The reason for this is that fine particles in the pre-coated iron oxide particles
Due to the extremely fine iron oxide fine particles adsorbed in the pores,
Decrease in adsorption capacity of iron oxide particles as precoat agent or
Extremely fine iron oxide in heater drain water resulting in loss
Fine particles no longer adsorb to pre-coated iron oxide particles
Iron oxide fine particles that pass through to the secondary side of the membrane filter
It is considered that the amount increases. At the peak position of the pore radius distribution of the particles
The smaller the pore radius and the larger the specific surface area, the more
Extremely fine particles in the heater drain water into particles as an agent
It is considered that the adsorption amount of the iron oxide fine particles increases. Follow
To remove extremely fine iron oxide particles in the heater drain water.
In order to remove it, the peak position of the pore radius distribution
The pore radius is as small as 0.2 μm or less, and the specific surface area is 5 m²
/ G or larger particles maintain their iron removal performance.
It is thought that the time to hold it will be longer. Examples described later
To use such particles as a precoat agent
It was confirmed that the iron removal performance retention time was extended. The particles (hereinafter referred to as particles) used as a precoat agent
Below, sometimes referred to as "precoat agent particles")
When the pore radius at the peak position of the cloth is 0.2 μm or less, the specific surface
Product is 5m²/ G
May be included in the power plant condensate system.
Γ-FeOOH or γ-Fe of the same material as
₂O₃And the like are preferred. In addition to these,
The pore radius at the peak position of the pore radius distribution is 0.2 μm or less
And the specific surface area is 5m²/ G or more activated carbon particles, porous
Glass particles, zeolite particles, etc. can also be used.
You. The pore radius at the peak position of the pore radius distribution is preferably
Is 5 × 10^-FourUp to 0.2 μm (0.5 nm to 0.2 μm)
Range. The specific surface area is preferably 5 to 20.
00m²/ G. The particle size of such a precoating agent is
Depends on the type of filter, etc.
Not impervious, but filter impervious to precoat agents
And peelability after use, and oxidation in heater drain water
From the viewpoint of the ability to capture iron fine particles (that is, iron removal performance), it is preferable.
0.5 to 20 μm, more preferably 1 to 10 μm
m. In addition, the amount of the precoat agent used is
It depends on the type, etc.
A suitable amount may be determined, for example, iron oxide particles
In the case of iron, the iron removal performance and its stability over time and economics
From 5 to 1 as the coating amount on the filtration surface of the filter.
00g-Fe / m²Is preferably in the range of 20 to 100 g
-Fe / m²Is more preferable. The filter used for filtration in the method of the present invention
Pre-coating agent particles on the filtration surface of the filter
And apply a filtration treatment with the pre-coated film formed.
Any material and form can be used if it can be used
No. For example, from the aspect of the filter element shape,
Empty thread type filter, pleated type filter, disk type
Filter element, etc.
In terms of material, polymer membrane filters and ceramic filters
Filter, metal filter, sintered metal filter, car
Various types of organic and inorganic filters such as Bon filters
Can be mentioned. [0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.
Embodiments will be described with reference to the drawings, but the present invention is not limited thereto.
It is not done. As a filter, as described above
In addition, hollow fiber type filters and pleated type filters
Filter, disc filter and polymer membrane filter
Filter, ceramic filter, metal filter, baking
Use of tying metal filter, carbon filter, etc. is possible
However, in this embodiment, as an example, a polymer
Hollow fiber membrane (hereinafter simply referred to as “hollow fiber membrane”) filter
Will be described. FIG. 1 shows a filter device used in this embodiment.
It is a block diagram showing a structure. FIG. 2 is used in this embodiment.
Sectional view showing a hollow fiber membrane module installed in a filtration device
It is. FIG. 3 shows power generation using the filtration device shown in FIG.
Diagram showing the peripheral system of the low-pressure water heater in a power plant
It is. The hollow fiber membrane module used in this embodiment
1 has a pore size of 0.01 to 0.3 μm as shown in FIG.
Outer diameter 0.2-7mm, inner diameter 0.1-5m with micro holes
m of the hollow fiber membrane 2 (filter element)
Approximately 50,000 pieces are stored in the protective cylinder 3, and
Without closing the upper end of the hollow fiber membrane 2
Adhering at the upper joint 4 and closing the lower end of each hollow fiber membrane 2
It is bonded at the lower joint portion 5, and the lower portion and the upper portion
Parts are provided with distribution ports 6A and 6B, respectively,
An opening 7 is provided in the joint 5 and the protective cylinder 3 is further moved slightly downward.
The skirt 8 is formed by extension. In this
In the hollow fiber membrane module 1, the lower end of all the hollow fiber membranes 2 is closed.
It is a one-end water collection type that collects water from the upper end
However, of course, various types of water collection from both ends of the hollow fiber membrane
A hollow fiber membrane module of the type can also be used. The hollow fiber membrane module 1 is connected to a filtration tower
In placing the filter in the filter tower 9 as shown in FIG.
A partition plate 10 is provided in an upper part of the filter 9 and the inside of the filtration tower 9 is
A large number of hollow fiber membrane modules are partitioned into the lower
The partition 1 is suspended in the vertical direction of the partition plate 10. Further, a bubble distribution mechanism 11 is disposed in the filtration tower 9.
Place. The air bubble distribution mechanism 11 includes a bubble receiver 12 and the air
It is composed of a bubble distribution pipe 13 penetrating the bubble receiver 12.
Therefore, the hollow fiber membrane module 1
It is assumed that the air bubble distribution pipe 13 corresponds. The filtered water outflow pipe 14 is provided above the filtration tower 9.
Of the raw water inflow pipe 1 at the lower part of the filtration tower 9
6, one end of the compressed air inlet pipe 15 and the drain
One ends of the pipes 18 are communicated with each other, and
One end of the air vent pipe 17 communicates with the side body of the filtration tower 9 immediately below
I do. Further, the pipe 1 attached to the upper part of the filtration tower 9
4 and a circulation pipe 19 is provided.
This pipe 19 flows through the raw water flow near the inlet of the filtration tower through 19P.
It is connected to the inlet pipe 16 and is distributed from the top of the filtration tower to the entrance of the filtration tower.
The pipes are connected, forming a circulation line.
Has formed. Further, the coating film type attached to the filtration tower 9
As shown in FIG. 1, the forming device 20 includes water [for example, pure water or
Pre-coating agent particles in system water (heater drain water)
A storage tank 20A for storing the suspension water prepared by addition,
A pipe 20 for communicating the storage tank 20A with the circulation pipe 19
B, and the pipe 20B is sequentially disposed from the upstream side.
And an injection pump 20C and a valve 20D. In addition,
Compressed gas is stored in the storage tank 20A instead of the injection pump 20C
The suspension may be introduced to serve as a driving force for supplying the suspension water. Further, 19C, 19D, 20D, 22-2
6 indicates a valve, and 28 indicates a baffle plate (baffle plate).
le plate). The treatment of the present invention is carried out using the above-mentioned filtration device.
As an example of the target of treatment (water to be treated),
Pressure water heater drain water (raw water in filtration tower)
Is processed according to the method of the present invention. First, with reference to FIG.
Low-pressure feed water heater (low
The peripheral system of the pressurized water heater will be briefly described. The system in FIG.
Is driven by steam from a steam generator (not shown)
The low-pressure turbine 31 converts the steam of the low-pressure turbine 31 into water.
A condenser 32 to be returned, and a pump 33 from the condenser 32
A condensate desalination device 34 for desalinating the condensed water sent,
The water is desalinated from a condensate desalination unit 34 via a pump 35.
The condensed water is supplied to the steam supplied from the low-pressure turbine 31 (indicated by a dotted line).
Low pressure feed water heater 36 which is heated by
Have. And, in this low pressure water heater 36,
Condensed water heated by heating is supplied to a high-pressure water heater (not shown).
And sent to the steam generator via As shown in FIG.
The low-pressure water heater 36 has the above-mentioned pre-coating film.
A filtering device 37 with a forming device is provided. This filtration device
The heater drain water is filtered by the device 37, and the heater drain water is filtered.
Impurities mainly composed of iron oxide fine particles were removed from the water.
The obtained filtered water is added in the low-pressure water heater 36.
It merges with the heated condensed water. The heater drain water to be treated (hereinafter referred to as “water”)
Prior to the passage of “raw water”, the upper chamber F of the filtration tower 9
And the inside of the lower chamber R is filled with pure water. Next, prior to the filtration step
Standing, the pore radius at the peak position of the pore radius distribution (hereinafter,
"Pore distribution peak radius" is 0.2 μm or less,
5m specific surface area²/ G or more of pre-coating agent particles in water
The suspension water prepared by the addition is passed through a filtration tower 9 and the hollow fiber membrane 2
Forming a coating film of the precoat agent particles on the filtration surface of
Good. For forming a coating film of pre-coating agent particles
First, the upper chamber F and the lower chamber R of the filtration tower 9 are filled with pure water.
After that, the precoat agent particles are stored in the storage tank 20A.
In water (for example, pure water or system water (heater drain water))
To prepare suspension water having a predetermined particle concentration. Then
The valves 19C and 19D of the circulation pipe 19 are opened, and the circulation pump is opened.
When the pump 19P is activated, the water in the filtration tower 9 is circulated to the circulation pipe.
It circulates through 19 to form a circulation system. Next, the valve 20D of the coating film forming apparatus 20 is opened.
When the valve is started and the infusion pump 20C is started, the precoat agent particles
The suspension containing the particles is supplied via pipes 20B, 19 and 16
It flows into the lower chamber R of the filtration tower 9. This allows pre-coating
The suspension containing the agent particles is a hollow fiber membrane in the lower chamber R of the filtration tower 9.
Filtered by the hollow fiber membrane 2 in the module 1
The coating film of the agent particles is formed on the surface of the hollow fiber membrane 2.
Then, the precoat agent particles on the filtration surface of the hollow fiber membrane 2
Is a predetermined amount (for example, 25 to 80 g-particles /
m²), The valve 20D is closed and the infusion pump 20
Stop C. In this way, prior to the passage of raw water,
The agent particles are pre-coated on the surface of the hollow fiber membrane 2. In the filtration step, the raw water inflow pipe 16
And the raw water (heater drain water) flows into the lower chamber R of the filtration tower 9.
And the hollow fiber membrane module 1 is used
The particles are filtered, and the filtered water is placed at the top of each hollow fiber membrane module 1.
Out of the system from the filtered water outlet pipe 14
Leaked to By continuing the filtration, the differential pressure of the filtration tower 9 is increased.
Rises and reaches the specified differential pressure when scrubbing
The process is implemented. Here, during the scrubbing process
In order to avoid skin roughness on the surface of the empty yarn membrane 2 as much as possible,
Prior to the filtration process, the raw water temperature in the lower chamber R of the filtration tower 9 is lowered.
Measures can be taken (see JP-A-4-1356).
No. 32), fine particles that peel off at the beginning of the scrubbing process
After removing the child, continue the scrubbing process,
Cleaning waste containing fine particles that peel off at the beginning of the scrubbing process
Adding a preliminary blow step for discharging water from the lower chamber R
(Japanese Patent Application Laid-Open No. 4-10023). The iron oxide fine particles adhering to the surface of the hollow fiber membrane 2 are
The scrubbing process for removal is performed as follows:
It is. The valves 22 and 26 are closed, the raw water is supplied to the lower chamber R, and the upper chamber F
With the filtered water still filled, the valves 24 and 25 are opened,
Compressed air is caused to flow from the compressed air inflow pipe 15. Compressed air
Is temporarily received on the lower surface of the bubble receiver 12, and thenBubble distribution
Air bubbles are generated from the air flow holes 13A of the tube 13 to form hollow fiber membrane modules.
Into the skirt 8 of the joule 1 and then to the opening 7
Flows into each hollow fiber membrane module 1 through these
Each hollow fiber membrane 2 oscillates with the rise of bubbles in
The water in the hollow fiber membrane module 1 is stirred,
The fine particles of iron oxide contained in the raw water captured on the surface
Precoating agent particles formed prior to water flow
Then, it is dispersed in the lower chamber R of the filtration tower 9. The bubbles are hollow
The hollow fiber membrane module is connected through the distribution port 6B of the fiber membrane module 1.
Out of the filter 1, and then through the air vent pipe 17 to the filtration tower 9.
It is discharged outside. The exfoliated by the above-mentioned scrubbing, the filtration tower
9 and iron oxide fine particles dispersed in water in the lower chamber R and Prico
After the scrubbing, the spray agent particles are blown out of the filtration tower 9.
I do. That is, the valve 24 is closed while the valve 25 is opened,
Open valve 23 to remove the washing wastewater in which iron oxide fine particles are dispersed.
The liquid is discharged through the drain pipe 18. In addition, wash wastewater
The blow process to make use of the head difference
Is compressed air from the air vent pipe 17 or the compressed air inflow pipe 15.
Air, and perform rapid outflow using the air pressure.
You can also. A stirrer that stirs water with the compressed air described above
After the rubbing process and the cleaning wastewater blowing process are completed,
Through the pre-coating agent particle coating film forming step as described above,
The raw water flow filtration step is performed again. Incidentally, other systems in the power plant, for example,
Most of the iron oxide particles in condensate have pore distribution peak radius
Is 0.2 μm or less and the specific surface area is 5 m²/ G or more
If it is a particle, a filter that can capture this iron oxide particle
Is installed in the condensate system, and the oxidation captured by this filter is
For forming a coating film using iron particles as a precoating agent for the hollow fiber membrane 2
It can also be used. [0042] The present invention will be described in more detail with reference to the following examples.
However, the present invention is not limited by this example.
There is no. Examples 1-3 and Comparative Examples 1-2 In this example and the comparative example, the same as the filtration device shown in FIG.
The following experiment was performed using the small experimental filtration apparatus of a structure.
First, in the same manner as in the above-described embodiment, the precoat agent particles
Suspended water prepared by mixing the particles in pure water is passed through a filtration tower,
A precoat agent-coated membrane was formed on the surface of the hollow fiber membrane. Pre
The following iron oxides were used as coating agents, respectively.
The amount of coating (the amount of coating on the filtration surface of the filter) is 2
0 g-Fe / m²And Then the low pressure in the power plant
Filtration tower for drain water (water temperature: 60-70 ° C)
Water. The change with time of the iron removal rate at this time was tracked. Ma
For comparison, the pre-coating agent-coated membrane was coated on the surface of the hollow fiber membrane.
The heater drain water is passed through the filtration tower without forming
The change over time in the iron removal rate was tracked as described above. FIG. 4 shows these results.
Shown in The iron content used to determine the iron removal rate
The quantitative method is based on the TPTZ method (2, JIS-B-8224).
4,6-tri-2-pyridyl-1,3,5-triazine
Absorptiometry). Also, the pore content of the precoat agent particles
The cloth peak radius is measured by the mercury intrusion method (to
The specific surface area can be measured by the BET method.
Measured. <Specifications of experiment using small experimental filtration device>   Hollow fiber membrane module Pore size of hollow fiber membrane: 0.14 μm Same outer diameter: 1.0mm Same inner diameter: 0.7mm Same effective length: 1100mm The same number: 250   Number of hollow fiber membrane modules used: 1 The hollow fiber membrane area: 0.86m²   Filtration flow rate: 0.3 m / hr   Iron oxides as pre-coating agents (symbols in FIG.
(Corresponds to sign) ×: No precoat (Comparative Example 1) (2) (dotted line): Fe₃O₄, Pore distribution peak radius:
0.264 μm, specific surface area: 4.7 m²/ G (Comparative Example
2) ◆ (dotted line): γ-Fe₂O₃, Pore distribution peak half
Diameter: 0.065 μm, specific surface area: 21.6 m²/ G (actual
Example 1) ▲ (solid line): Condensate cladding, pore distribution peak radius:
0.042 μm, specific surface area: 33.5 m²/ G (Example
2) ● (dashed line): γ-FeOOH, pore distribution peak half
Diameter: 0.079 μm, specific surface area: 23.5 m²/ G (actual
Example 3) According to the results shown in FIG. 4, the precoat agent
Pore distribution peak radius of iron oxide particles used as 0.2μ
m or less, specific surface area is 5m²/ G or more (Example
1 to 3) when no precoat agent was used (compared to
Comparative Example 1) Pore of iron oxide particles used as precoat agent
Distribution radius is 0.2μm or more, specific surface area is 5m²Less than / g
Is better than that of Comparative Example 2 (Comparative Example 2).
Was confirmed. Especially in Examples 2 and 3, iron removal
Performance was stable for a long time. In addition, in Example 1,
Even if the precoat amount is increased, the iron removal performance is stable over time
It is expected that the performance will be improved. [0046] EFFECT OF THE INVENTION The treatment of the power plant heater drain water of the present invention
According to the method, iron in the heater drain water in the power plant
Oxide particles can be removed stably and reliably,
Iron oxide fines to steam generator or boiler of power plant
Particles can be effectively prevented from being brought in.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a structure of a filtration device used in one embodiment of the present invention. FIG. 2 is a sectional view showing a hollow fiber membrane module installed in a filtration device used in one embodiment of the present invention. FIG. 3 is a flowchart showing a peripheral system of a low-pressure water heater in a power plant in which the filtration device shown in FIG. 1 is used. FIG. 4 shows a case where a coating film of precoating agent particles having a pore distribution peak radius and a specific surface area specified by the present invention is formed on the surface of a hollow fiber membrane (Example) and a case where a precoating agent is used. The hollow fiber membrane filtration tower was used in the case where the coating film was not formed and the case where the coating film of the precoating agent particles having no pore distribution peak radius and specific surface area specified in the present invention was formed on the surface of the hollow fiber membrane (Comparative Example). It is a graph which shows the experimental result which traced the time-dependent change of the iron removal rate with respect to heater drain water. [Description of Signs] 1 Hollow fiber membrane module 2 Hollow fiber membrane 3 Protective cylinder 4 Upper joint section 5 Lower joint section 6A Flow port 6B Flow port 7 Opening 8 Skirt section 9 Filtration tower 10 Partition plate 11 Bubble distribution mechanism 12 Bubble receiver 13 Bubbles distribution pipe 13A Air circulation hole 14 Filtration water outflow pipe 15 Compressed air inflow pipe 16 Raw water inflow pipe 17 Air release pipe 18 Drain pipe 19 Circulation pipe 19P Circulation pump 20 Coating film forming apparatus 20A Storage tank 20B Pipe 20C Injection pump 19C , 19D, 20D, 22-26 Valve 28 Baffle plate F Upper chamber R Lower chamber 31 Low-pressure turbine 32 Condenser 33 Pump 34 Condensate desalination device 35 Pump 36 Low-pressure water heater 37 Filtration device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FIG21F 9/06 521 G21C 19/30 GBDD GDPD (72) Inventor Toshio Morita 1-2-8 Shinsuna, Koto-ku, Tokyo Organo shares In-company (72) Inventor Shogo Umemoto 1-8-2 Shinsuna, Koto-ku, Tokyo Organo Co., Ltd. (56) References JP-A-10-94719 (JP, A) JP-A-9-187769 (JP, A) JP-A-63-315190 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 37/02 B01D 61/20 C02F 1/44 G21C 19/307 G21F 9/06 521

Claims (1)

(57) [Claim 1] When removing iron from heater drain water in a power plant by a filter, a peak position of a pore radius distribution is used as a pre-coating agent for a filter for improving the iron removing effect. A method for treating power plant heater drain water, comprising using particles having a pore radius of 0.2 μm or less and a specific surface area of 5 m ² / g or more.