JPH10305A - Method of preventing deaerator from being clogged - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent a deaerator from being clogged even without reversing the water passing direction. SOLUTION: This device is formed by containing a housing part 6 which an aggregate of hollow yarn like air separation membranes 5 is incorporated to form, a cap 7a on the inflow side which is fitted to the inflow side of the housing part 6, and an air intake part 8 for sucking dissolved gas molecules in raw water through the hollow yarn like gas separation membranes. In this case, a dispersant is injected to raw water fed to a deaerator body 2a, and also floating bodies 9a are fluidized inside the cap on the inflow side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reliably preventing clogging of a deaerator used in a water supply line of a boiler or the like.

[0002]

2. Description of the Related Art In recent years, a deaerator has been used as a measure for preventing red water in buildings and condominiums. Dewatering devices are also incorporated in water supply lines for cooling and heating equipment such as boilers, water heaters, and coolers in order to prevent internal corrosion of these equipment. As a degassing device, a device using a hollow fiber-shaped gas separation membrane module is often used because of its compactness and easy handling. In this type of deaerator, while raw water flows through the gas separation membrane, a vacuum pump is operated via the gas separation membrane to separate and remove dissolved gas in the raw water.

[0003]

However, in the above-described deaerator, impurities such as iron, manganese, and mud in the raw water adhere to the inflow-side end face of the gas separation membrane module and grow with time. There is a problem. In consideration of such a situation, a filtration filter is generally provided on the upstream side of the deaeration device. However, the inflow side end face of the hollow fiber-shaped separation membrane is still gradually clogged (clogged) by a component that passes through the filtration filter. As a result, the pressure loss of the deaerator increases and the deoxygenation ability decreases. Further, the life of the gas separation membrane module itself is shortened. In order to prevent clogging of the deaerator, for example, it is conceivable to reverse the direction of water flow after a lapse of a predetermined time.However, this method has a disadvantage that a switching mechanism becomes complicated and manufacturing costs increase. Yes, not enough solution. The present invention has been made in view of these problems, and it is an object of the present invention to provide a method capable of reliably preventing clogging of a deaerator without reversing a water flow direction. And

[0004]

In order to achieve the above object, according to the present invention, there is provided a housing portion having a built-in hollow fiber gas separation membrane, and an inflow side mounted on the inflow side of the housing portion. In a deaerator including a cap and an intake unit that sucks dissolved gas molecules in the raw water through the hollow fiber-shaped gas separation membrane, while injecting a dispersant into the raw water supplied to the deaerator, A floating body flows inside the inflow-side cap. In the present invention, since the dispersant is injected into the raw water supplied to the deaerator and the floating body is flowing inside the inflow-side cap, the clogging component may aggregate and grow into a solid. And clogging can be reliably prevented. In general, a prefilter is provided in the deaerator, but in this case, it is preferable to inject the dispersant immediately upstream of the inflow-side cap. In the present invention, the floating body is not particularly limited as long as it flows in accordance with the flow of the raw water. For example, a floating body having a relatively low specific gravity such as plastic beads is preferable. Although the shape of the floating body is not particularly limited, for example, a shape such as a sphere, a rice grain, and a column is exemplified.

The dispersants of the present invention include natural organic substances (a) such as lignin and tannin, polymerized phosphates (b) such as hexametaphosphate, and aminotrimethylene phosphonates and phosphonobutane tricarboxylates. Phosphonate (c),
Acrylic acid homopolymer, acrylic acid copolymer,
Acrylic acid-based polymers such as acrylic acid-based terpolymers
(d), a maleic acid-based polymer (e) such as a maleic acid homopolymer or a maleic anhydride-based copolymer, or an acrylamide-based homopolymer (f), or any combination thereof. In addition to preventing clogging of the deaerator, it is effective to use the following dispersant in order to suppress scale deposition in a boiler or the like. First, when precipitation of calcium carbonate is expected, various phosphonates, maleic acid homopolymers, and acrylic acid homopolymers are preferred. When precipitation of calcium phosphate is expected, an acrylic acid-based terpolymer or a maleic acid-based copolymer is preferred. When precipitation of magnesium silicate is expected, an acrylic acid-based copolymer, an acrylamide-based homopolymer, or a maleic acid-based copolymer is preferred. Further, when precipitation of calcium sulfate is expected, a polymerized phosphate, a phosphonate, or an acrylic acid homopolymer is preferable.

[0006] The chemical concentration of the dispersant is 0.1 mg / l to 5 mg / l.
00 mg / l is preferred, more preferably 1 mg / l
About 100 mg / l. The present invention may include other components as long as the object of the invention is not impaired.
In the case of a deaerator used for a boiler, the following components may be added. For pH adjustment for anticorrosion, sodium hydroxide NaOH, potassium hydroxide KO
H may be added. To further improve the deoxidizing effect, a deoxidizing agent such as sodium sulfite Na ₂ SO ₃ or hydrazine may be added. To prevent corrosion of the steam piping, a condensing agent such as a film type amine, a neutralized type amine, or hydrazine may be added. An antifoaming agent may be added to prevent carryover.

[0007]

【Example】

[Embodiment 1] The present invention is implemented in an apparatus configuration as shown in FIG. FIG. 1 shows a part of a water supply line of a boiler, and a chemical injection device 1 for injecting a dispersant and the like.
, A deaerator 2, a storage tank 3, and a boiler 4 are illustrated. The degassing device 2 is configured to include a device main body 2a for removing dissolved gas in raw water, and a pre-filter 2b disposed upstream of the device main body 2a. As shown in FIG. 2, the apparatus main body 2 a includes a housing portion 6 having a built-in assembly of the hollow fiber gas separation membrane 5, an inflow side cap 7 a mounted on the inflow side of the housing portion 6, Outlet side cap 7b mounted on the outflow side of the air, and suction unit 8 for inhaling dissolved gas molecules in raw water through hollow fiber gas separation membrane 5.
And the floating bodies 9a, 9a, which flow inside the caps 7a, 7b.
9b. In this deaerator 2,
Although the inflow side and the outflow side are appropriately switched so that the water flow direction can be reversed, this is not always necessary, and when the reverse water flow is not performed, the floating body 9b may be omitted. In the apparatus configuration shown in FIG. 1, when the raw water has a high silica concentration, a low M alkali (metal alkali), and a water quality in which a silica-based scale is concerned, 20% sodium hydroxide, 1-
When 20 mg / l of an aqueous solution containing 30% of hydroxyethylidene-1,1-diphosphonic acid was used, it was confirmed that the performance of the deaerator did not deteriorate even after long-time use. In addition, when the M alkali of the raw water was high, when an aqueous solution containing 30% of sodium hexametaphosphate was used at 20 mg / l, it was confirmed that the performance of the deaerator did not deteriorate even after long-time use. In addition, the pre-filter 2b and the device body 2
The chemical infusion device 1 was connected between a (see a broken line in FIG. 1), and the same chemical solution as described above was injected. In this case, the dispersant is preferably injected into the raw water after passing through the pre-filter 2b.

[Example 2] Four deaerators A, B, C, and D having the same capacity were prepared, and a comparative test was performed using raw water containing a predetermined amount of iron colloid, dust, and dissolved oxygen. .
More specifically, a flow meter and a dissolved oxygen meter are provided downstream of each of the deaerators A to D, and the flow rate and the dissolved oxygen amount (DO value)
, And a pressure gauge was provided between the inflow side and the outflow side of each deaerator to measure the time change of pressure loss. (1) Implementation of the present invention (degassing devices A and B) To raw water supplied to degassing devices A and B, 0.2% by weight of sodium hexametaphosphate is added as a dispersant. Plastic beads (hereinafter, referred to as beads) are inserted into the deaerator A as a floating body, and water flows only in one direction. On the other hand, no beads are inserted into the deaerator B, but the water flow direction is reversed during operation. (2) Comparison device (degassing devices C and D) Raw water without a dispersant is supplied to the degassing devices C and D. Beads are inserted into the deaerator C, and water is passed in only one direction. On the other hand, no beads are inserted into the deaerator D, but the water flow direction is reversed during operation.

(3) Temporal change of pressure loss FIGS. 3 (a) and 3 (b) show temporal changes of pressure loss in the degassing devices A to D. In the case of the deaerator A in which the beads were inserted, since the dispersant was added to the raw water, it was confirmed that the pressure loss maintained a normal value of 0.45 Kg / cm ² . In the case of the deaerator B without beads, the pressure loss increases. However, when the water flow direction is reversed after 60 minutes, the pressure loss becomes 0.45.
It is confirmed that a normal value of about Kg / cm ² is maintained. In the case of the deaerator C operated without adding a dispersant to the raw water, the pressure loss gradually increases with the passage of time even if the beads are moved. If the pressure loss increases by 20% or more from the normal value, there is a problem in operation. In the deaerator D in which the beads are not inserted and the operation is performed without adding a dispersant to the raw water, the pressure loss rapidly increases after the operation is started, and even if the water flowing direction is reversed after 30 minutes, the pressure loss is reduced. Only recovers slowly. (4) Temporal change of flow rate FIGS. 4A and 4B illustrate the temporal change of the flow rate for the deaerators A to D. In the case of the deaerator A in which the beads were inserted, it was confirmed that the flow rate hardly decreased because the dispersant was added to the raw water.
In each deaerator, the normal flow rate was 16.5 to 1
The flow rate is about 6.9 l / min. If the flow rate is reduced by 20% or more, there is a problem in operation. In the case of the deaerator B in which the beads are not inserted, the flow rate decreases when the operation is started. However, when the water flow direction is reversed after the elapse of 60 minutes, the normal flow rate can be maintained. It is confirmed. In the case of the deaerator C in which the dispersant is not added to the raw water, the flow rate decreases with time even if the beads are moved. In the deaerator D in which beads were not inserted and the dispersant was not added to the raw water, the flow rate suddenly decreased after the start of the operation, and even if the flow direction was reversed after 30 minutes, The flow rate is
It only recovers slowly.

(5) Temporal change of DO value FIGS. 5 (a) and 5 (b) show the temporal change of the DO value for the deaerators A to D. In the case of the deaerator A in which the beads were inserted, it was confirmed that the DO value hardly increased from 0.5 ppm because the dispersant was added to the raw water. In the case of the deaerator B in which beads are not inserted, the DO value sharply increases when the operation is started. However, if the water flow direction is reversed after the elapse of 60 minutes, the normal flow rate may be maintained thereafter. confirmed. In the case of the deaerator C in which the dispersant is not added to the raw water, the DO value increases with time even if the beads are moved. In the deaerator D in which beads were not inserted and the dispersant was not added to the raw water, the flow rate suddenly decreased after the start of the operation, and even if the flow direction was reversed after 30 minutes, DO values only recover slowly.

[0011]

As described above, according to the present invention,
Clogging of the deaerator can be reliably prevented without reversing the direction of water flow during operation. When the present invention is applied to a water supply line of a building or the like, by using polymerized phosphoric acid as a dispersant, prevention of clogging and prevention of generation of red water can be realized. In addition, when the present invention is applied to a water supply line such as a boiler, prevention of scale can be realized by injecting a dispersant.

[Brief description of the drawings]

FIG. 1 illustrates a part of a water supply line of a boiler.

FIG. 2 illustrates an internal configuration of a deaerator.

FIG. 3 illustrates a temporal change of a pressure loss.

FIG. 4 illustrates a temporal change of a flow rate.

FIG. 5 is a diagram illustrating a temporal change of a dissolved oxygen amount.

[Explanation of symbols]

 2 Degassing device 5 Hollow fiber gas separation membrane 6 Housing 7a Inlet-side cap 8 Inlet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichi Kimura 7th Horie-cho, Matsuyama-shi, Ehime Miura Kogyo Co., Ltd. Inventor Moto Abe 7-Horiecho, Matsuyama-shi, Ehime Miura Industrial Co., Ltd.

Claims (4)

[Claims] 1. A housing section containing an assembly of hollow fiber-shaped gas separation membranes, an inflow side cap mounted on the inflow side of the housing section, and dissolution in raw water via the hollow fiber-shaped gas separation membranes. A degassing device including a suction part for sucking gas molecules, wherein a dispersant is injected into raw water supplied to the degassing device, and a floating body flows inside the inflow-side cap. To prevent clogging of the deaerator. 2. The method of claim 1, wherein the dispersant is injected immediately upstream of the inlet cap. 3. The dispersant is one or more selected from natural organic substances, polymerized phosphates, phosphonates, acrylic acid polymers, maleic acid polymers, and acrylamide homopolymers. The method for preventing clogging of a deaerator according to claim 1 or 2, which is a mixture of: 4. The addition concentration of the dispersant is 0.1 mg /
The method for preventing clogging of a deaerator according to claim 3, wherein the amount is 1 to 500 mg / l.