JP2008089204A - Deoxygenated water supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deoxygenated water supply system capable of surely preventing back-flow of water from a makeup tank to a water supply tank even though a check valve is not disposed on a communicating means for communicating a lower part of the makeup tank and a lower part of the water supply tank. <P>SOLUTION: This deoxygenated water supply system comprises the makeup tank 1 to which the makeup water is supplied from a makeup water source at a flow rate of D(m<SP>3</SP>/hr), a deoxygenating device 3 to which the water is supplied from the makeup tank 1 at a flow rate E(m<SP>3</SP>/hr), the water supply tank 5 to which the deoxygenated water is supplied from the deoxygenating device 3 through a water supply pipe 6, a communication pipe 7 for communicating the lower parts of the makeup tank 1 and the water supply tank 5, and a water delivering pipe 8 branched from the water supply pipe 6 for delivering the deoxygenated water to a boiler. A value of A defined by a formula A=(E-B)+[S<SB>2</SB>/(S<SB>1</SB>+S<SB>2</SB>)]×(B-D) is constantly positive when an estimated maximum water delivering amount to the boiler is B(m<SP>3</SP>/hr), an average horizontal cross-sectional area of the makeup tank 1 is S<SB>1</SB>(m<SP>2</SP>), and an average horizontal cross-sectional area of the water supply tank 5 is S<SB>2</SB>(m<SP>2</SP>). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a deoxygenated water supply system for supplying deoxygenated water (degassed water) to a place of use as boiler, water supply / hot water supply equipment, process water for food industry, water for semiconductor industry, and the like. Specifically, the present invention receives makeup water in a makeup water tank, introduces the water in the makeup water tank into dewatered water using a deoxidizer, and then supplies a portion of the deoxygenated water to a demand location. In addition, the present invention relates to a deoxygenated water supply system in which the lower part of the makeup water tank and the water tank are communicated with each other.

  As this type of deoxygenated water supply system, there is a system described in Japanese Patent Application Laid-Open No. 8-141577.

  The deoxygenated water supply system disclosed in the publication includes a make-up water chamber to which make-up water is replenished, a deoxygenation device to which water in the make-up water chamber is supplied, and a water supply chamber to which deaerated water is supplied from the deoxygenation device. And a water supply pipe for supplying the deaerated water in the water supply chamber to the place of use, and the make-up water chamber and the water supply chamber communicate with each other. In the deoxygenated water supply system of FIG. 1 of the same publication, the lower part of the makeup water chamber and the lower part of the water supply chamber are connected by a pipe having a check valve, and water goes from the water supply chamber to the makeup water chamber. It is configured to flow only in the direction. This is to prevent undeoxygenated water in the makeup water chamber from flowing directly into the water supply chamber.

In the third page, third column, lines 13 to 14 of the publication, it is stated that “the circulation valve is always circulated, so this check valve may be omitted”.
Japanese Patent Laid-Open No. 8-141577

  When the check valve is provided in the pipe connecting the lower part of the makeup water chamber and the lower part of the water supply chamber as in the deoxygenated water supply system of FIG. However, there is a disadvantage that the entire system becomes inoperable only when the cost becomes high or the check valve fails. In this case, all boilers supplied with water from this deoxygenated water supply system are forced to shut down, and the factory operation must be interrupted for several days, resulting in considerable damage.

  If the check valve is omitted as described in JP-A-8-141577, page 3, column 3, lines 13 to 14, water having insufficient oxygen removal from the makeup water chamber to the water supply chamber. May flow backward and the oxygen concentration of the feed water to the boiler or the like may increase.

  In the boiler, the amount of steam generated is constantly changing according to the requirements of the site. Especially when it is necessary to generate a larger amount of steam than usual, the system of FIG. The supply of water is not in time, and the boiler operation must be interrupted. For this reason, it exists in the tendency to install the boiler of the steam generation amount larger than usual, and a large capacity | capacitance water tank.

  The present invention solves such problems and reliably prevents backflow of water from the replenishing water tank to the water supplying tank even if there is no check valve in the communication means that connects the lower part of the replenishing water tank and the lower part of the water supplying tank. Further, an object of the present invention is to provide a deoxygenated water supply system capable of continuously supplying degassed water without any problems even when the amount of steam generated in the boiler is significantly increased than usual.

The deoxygenated water supply system of the present invention includes a make-up water tank supplied with make-up water at a flow rate D (m ³ / hr) from a make-up water source, and water from the make-up water tank at a flow rate E (m ³ / hr). A deoxygenation device to be supplied; a water supply tank to which deoxygenated water is supplied from the deoxygenation device via a water supply pipe; communication means for communicating the lower portions of the makeup water tank and the water supply tank; and the water supply pipe or the water supply In a deoxygenated water supply system having a water supply pipe for supplying deoxygenated water from a water tank to a deoxygenated water demand point, the expected maximum water supply amount to the deoxygenated water demand point is B (m ³ / hr) When the average horizontal sectional area of the makeup tank is S ₁ (m ² ) and the average horizontal sectional area of the water tank is S ₂ (m ² ), the value of A defined by the following equation is always positive. It is comprised so that it may be comprised.
A = (EB) + [S ₂ / (S ₁ + S ₂ )] · (BD)

  According to the deoxygenated water supply system of the present invention, even when the deoxygenated water supply amount to the deoxygenated water demand point is maximized, the communication means that communicates the lower part of the make-up water tank and the lower part of the water supply tank. Water always flows from the water tank to the makeup tank. For this reason, the non-deoxygenated water in the makeup water tank does not flow back to the water in the water tank via the communicating means, and the oxygen concentration in the water tank is kept at a sufficiently low value. As a result, there is no waste of installing a boiler with the maximum rated steam generation amount and usually operating at about 1/3 of its capacity, and the supply system of the present invention has achieved the maximum steam generation amount. Even when deaerated water can be supplied smoothly.

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

  FIG. 1 is a system diagram showing a deoxygenated water supply system according to an embodiment.

  In this deoxygenated water supply system, a makeup water tank 1 to which makeup water is supplied from a makeup water source (not shown) via a supplementary pipe 2, and water is supplied from the makeup water tank 1 through a water intake pipe 4. A deoxidizer 3, a water supply tank 5 to which deoxygenated water is supplied from the deoxygenator 3 through a water supply pipe 6, a communication pipe 7 that communicates the lower portions of the make-up water tank 1 and the water tank 5, A water supply pipe 8 that branches from the middle of the water supply pipe 6 and supplies deoxygenated water to a boiler (not shown) is provided. In this embodiment, a nitrogen-type deoxygenation device is used as the deoxygenation device 3.

  Reference numeral 2 a indicates an open / close valve of the supply pipe 2. Reference numeral 4 a indicates an open / close valve of the intake pipe 4, and reference numeral 4 b indicates a pump for feeding water from the make-up water tank 1 to the deoxidizer 3 through the intake pipe 4. Reference numeral 6a denotes a pump for sending deoxygenated water from the deoxygenator 3 through the water supply pipe 6 to the water supply tank 5 and the water supply pipe 8, and reference numeral 6b denotes an open / close valve on the water supply tank 5 side of the water supply pipe 6. Show. Reference numeral 7 a indicates an open / close valve of the communication pipe 7. The code | symbol 8a has shown the pump for supplying deoxygenated water to a boiler via the water supply pipe 8. FIG.

  The makeup water tank 1 is provided with a water level detection device (not shown) for detecting the water level in the makeup water tank 1. A valve opening / closing device 9 for opening / closing the opening / closing valve 2a based on a detection signal of the water level detection device is attached to the opening / closing valve 2a of the supply pipe 2.

  The valve opening / closing device 9 opens the valve 2a when the water level detecting device detects that the water level in the makeup water tank 1 is equal to or lower than a predetermined lower limit water level, and replenishes the makeup water tank 1 with water. When the water level detecting device detects that the water level in the inside has reached or exceeded the predetermined upper limit water level, the valve 2a is closed to stop the replenishment of water into the replenishing water tank 1. Thereby, the water level in the replenishing water tank 1 is kept substantially constant.

  In this embodiment, soft water is supplied to the makeup water tank 1 as makeup water.

  In this embodiment, heating steam is introduced into the makeup water tank 1 through the steam supply pipe 10. The make-up water tank 1 is provided with a water temperature detecting device 11 for detecting the water temperature in the make-up water tank 1, and the steam control valve 10a of the steam supply pipe 10 is set so that the detected water temperature of the water temperature detecting device falls within a predetermined range. It is controlled by the valve opening / closing device 12.

  In this embodiment, each of the replenishing water tank 1 and the water tank 5 has a substantially constant horizontal cross-sectional area from the lower end to the upper end of each.

  The on-off valve 7a is normally fully open, and the replenishing water tank 1 and the supply tank 5 are always in communication with each other via the communication pipe 7, so that the water levels inside each are always the same. ing.

  In this deoxygenated water supply system, the water in the make-up water tank 1 is supplied to the deoxygenator 3 by the pump 4 b through the intake pipe 4, and deoxygenated by the deoxygenator 3. The deoxygenated water generated by this deoxygenation device is supplied to the water supply tank 5 and the water supply pipe 8 by the pump 6 a through the water supply pipe 6. The deoxygenated water supplied to the water supply pipe 8 is supplied to the boiler through the water supply pipe 8 and the pump 8a.

In this deoxygenated water supply system, the flow rate of make-up water supplied from the make-up water source to the make-up water tank 1 through the make-up pipe 2 is D (m ³ / hr), and from the make-up water tank 1 through the intake pipe 4 The flow rate of water supplied to the deoxygenation device 3 (the processing amount of the deoxygenation device 3) is set to E (m ³ / hr), and the expected maximum water supply amount of deoxygenated water supplied to the boiler via the water supply pipe 8 is When B (m ³ / hr) is set, the average horizontal cross-sectional area of the replenishing water tank 1 is S ₁ (m ² ), and the average horizontal cross-sectional area of the water tank 5 is S ₂ (m ² ), it is defined by the following equation: The value of A to be set is always positive.
A = (E−B) + [S ₂ / (S ₁ + S ₂ )] · (BD) (1)

This A is the flow rate (m ³ / hr) of deoxygenated water supplied from the water supply tank 5 to the makeup water tank 1 via the communication pipe 7. Therefore, the fact that A is always positive means that water always flows from the water supply tank 5 to the makeup water tank 1 in the communication pipe 7 even when the amount B of deoxygenated water to the boiler becomes maximum. Means flowing.

In this deoxygenated water supply system, the flow rate of deoxygenated water supplied from the deoxygenator 3 through the water supply pipe 6 to the water supply tank 5 is changed from the make-up water tank 1 through the intake pipe 4 to the deoxygenation apparatus. 3 is the same as the flow rate of water supplied to E (m ³ / hr).

  In such a deoxygenated water supply system, even when the deoxygenated water supply amount B to the boiler reaches a maximum (usually about three times the rated evaporation of the boiler), the lower part of the make-up water tank 1 In the communication pipe 7 that communicates with the lower part of the water tank 5, water always flows from the water tank 5 toward the makeup water tank 1, so that the non-deoxygenated water in the makeup water tank 1 flows into the water in the water tank 5. The oxygen concentration in the water tank 5 is kept at a sufficiently low value. In addition, the time when the amount B of water supply becomes maximum usually does not continue for a long time but occurs intermittently.

  Moreover, by having comprised in this way, the water flows into the communicating pipe 7 which connects the lower part of the replenishing water tank 1 and the lower part of the water supply tank 5 in this communicating pipe 7 from the replenishing water tank 1 toward the water supplying tank 5. It is not necessary to provide a check valve for preventing the deoxygenated water, and the configuration of the deoxygenated water supply system can be simplified.

  In addition, said Formula (1) is calculated | required as follows.

The fluctuation ΔHq (m) of the water level in the make-up water tank 1 after a minute time Δt from a certain time is defined by the following equation.
ΔHq = (A + DE) · (H / Q) · Δt (2)
Q: Amount of water stored in the makeup tank 1 at a certain time (m ³ )
H: Water level in the replenishing water tank 1 (= in the water tank 5) at a certain time (m)

Further, the fluctuation ΔHp (m) of the water level in the water supply tank 5 after a minute time Δt from a certain time is defined by the following equation.
ΔHp = (− A−B + E) · (H / P) · Δt (3)
P: Amount of water stored in the water tank 5 at a certain time (m ³ )
H: Water level in the water supply tank 5 (= in the replenishment water tank 1) at a certain time (m)

As described above, in this deoxygenated water supply system, the water level in the make-up water tank 1 and the water level in the water supply tank 5 are always constant.
ΔHq = ΔHp
(A + DE). (H / Q) .DELTA.t = (-AB + E). (H / P) .DELTA.t

Solving this for A,
A = E− (DP + BQ) / (P + Q) (4)
It becomes.

When the total amount of water held in tanks 1 and 5 is K = Q + P (m ³ ), the above equation (4) is
A = (EB) + (P / K). (BD) (5)
Can be expressed as

Also, P and Q are each, using a horizontal cross-sectional area S ₂ of the horizontal cross-sectional area S ₁ and replenishing water tank 5 of the supply water tank 1,
Q = S ₁ · H (6)
P = S ₂ · H (7)
H: Water level in each tank 1 and 5 at a certain time (m ³ )
By substituting these formulas (6) and (7) into the above formula (4) or (5) and rearranging,
A = (E−B) + [S ₂ / (S ₁ + S ₂ )] · (BD) (1)
Is guided.

  Among these formulas, (EB) indicates the remaining capacity of the deoxygenation device 3. When this value becomes negative, it indicates that the amount of water supplied to the boiler exceeds the treatment capacity of the deoxygenation device 3.

  Moreover, (BD) has shown increase / decrease in the total amount of water in a system. When the amount of water supplied to the make-up water tank 1 increases, the dissolved oxygen concentration in the make-up water tank 1 increases.

  When there is no water supply into the system and water supply to the outside of the system (that is, when D = 0 and B = 0), the flow rate A passing through the communication pipe 7 is equal to the water treatment amount E in the deoxygenation device 3.

  When D = 0 and B <E, all water sent to the boiler is deoxygenated water from the deoxygenation device 3.

  When B = 0 and D <E, the entire amount of deoxygenated water from the deoxygenation device 3 is sent to the water supply tank 5. Water in the replenishing water tank 1 does not flow into the water supply tank 5 through the communication pipe 7.

  When B = 0 and D> E, the entire amount of water replenished to the replenishing water tank 1 is not sent to the deoxygenation device 3, and a part of the water is accumulated in the replenishing water tank 1, and the water level in the replenishing water tank 1 is To rise. At this time, the water in the replenishing water tank 1 may flow into the water supplying tank 5 through the communication pipe 7 so that the water level in the replenishing water tank 1 and the water level in the water supplying tank 5 become equal.

However, at this time, the rising speed of the water level in the water tank 5 due to the supply of deoxygenated water from the oxygen absorber 3 to the water tank 5 through the water pipe 6 is the replenishment of water to the makeup water tank 1. If the rising speed of the water level in the replenishing water tank 1 is exceeded, the water in the replenishing water tank 1 can be prevented from flowing into the water supply tank 5. Therefore, it is sufficient to set the _{(D-E) / S 1} < as E / _{S 2} conditions are met, the horizontal cross-sectional area _{S 1} of the horizontal cross-sectional area _{S 2} and replenishing water tank 1 of water tank 5. This condition corresponds to a special solution obtained by solving A> 0 (the right side of equation (1) is positive) with B = 0 in the equation (1).

[Procedure for determining the capacity of deoxidizer]
In designing the deoxygenated water supply system of the present invention, the required maximum treatment amount in the deoxygenation device 3 per unit time is based on the maximum water supply amount to the boiler per unit time and the total retained water amount K of the system. It is necessary to ask. Here, since the capacity of the water supply tank 5 is generally a capacity capable of supplying the water required by the boiler for about 1 hour, in this description, the unit time is assumed to be 1 hour.

Desirable determination procedures of the maximum processing capacity of the deoxidizer 3 in the deoxygenated water supply system of the present invention are as follows (i) to (vi).
(I) Make-up water amount D = the required maximum processing amount per hour (m ³ / hr).
(Ii) Water supply amount to the boiler B = maximum water supply amount (m ³ / hr).
(Iii) The treated water amount E ≧ depleted water amount D of the deoxidizer 3 is set. When setting the minimum value of E, E = D may be set.
(Iv) Total retained water amount K = required maximum processing amount per unit time = replenishment water amount D per unit time.
(V) In the above equation (5), A = 0, and this equation is solved for P to confirm that the water storage amount P <K in the water tank 5 is satisfied.
(Vi) If P ≧ K, the processing capacity of the deoxygenation device 3 is increased by about 10% and the procedures (i) to (v) are executed again. The processing capacity of the deoxidizer 3 is repeatedly increased by about 10% until P <K. If finally P <K, the processing capability of the deoxygenation device 3 at that time is set as an E value.

[Specific design example of deoxygenated water supply system]
Next, an example in which the necessary capacity of the deoxygenation device 3 is determined according to the above sequence when the maximum water supply amount to the boiler is 30 m ³ / hr will be described.

In addition, the deoxygenation apparatus 3 shall have the capability to produce 0.1 ppm deoxygenated water when the feed water temperature is 80 ° C.
First, the calculation is started with the required maximum throughput of the deoxygenation device 3 being 10 (m ³ / hr).

When this condition is applied to the above (i) to (v), the following (i) ′ to (v) ′ are obtained.
(I) 'Supplying water amount D = required maximum processing amount of deoxygenation device 3 10 (m ³ / hr)
(Ii) 'Water supply amount to boiler B 30 (m ³ / hr)
(Iii) 'Amount of treated water E 10 (m ³ / hr) of the deoxidizer 3
(Iv) 'Total retained water volume K 10 (m ³ )
(V) 'Water storage amount P 10 (m ³ ) in the water tank 5

In this case, as shown in (iv) ′ and (v) ′, the stored water amount P and the total retained water amount K are both 10 (m ³ ) and P = K. Therefore, as the deoxygenated water supply system of the present invention, Is unsuitable. Therefore, as described in (vi) above, when the above procedure (i) ′ to (v) ′ is executed again with the value of E being 1.1 times the above, that is, E = 11, P = 9.5 (m ³ Since P <K, it was confirmed that the design is suitable for the deoxygenated water supply system of the present invention.

In this case, the deoxidation device 3 having a throughput of 11 (m ³ / hr) or more is used, the capacity Q of the makeup water tank 1 is 0.5 (m ³ ), and the capacity P of the water supply tank 5 is 9.5 (m ³ ). If so, as long as the amount of water supplied to the boiler is 30 m ³ / hr or less, the dissolved oxygen concentration in the boiler feed water can be maintained at 0.1 ppm or less.

In the prior art, in this case, had to be the maximum water supply amount 30 (m 3 / ^hr) in accordance with selected deoxidation device processing power 30 (m 3 / ^hr) of the boiler In the present invention, an equivalent or higher capacity can be obtained with a deoxygenation apparatus having a processing capacity of about 1/3.

[Description of another form]
The above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment.

  In the above embodiment, the replenishing water tank 1 and the water tank 5 are independent from each other, and the lower parts thereof are communicated with each other through the communication pipe 7. For example, by dividing one water tank with a partition, The replenishing water tank 1 and the water tank 5 may be configured, and the replenishing water tank 1 and the water tank 5 may be communicated with each other by providing an opening in the lower part of the partition.

When the horizontal cross-sectional areas of the water tanks 1 and 5 slightly change in the height direction of the water tanks 1 and 5, the average value may be handled as the horizontal cross-sectional areas S ₁ and S ₂ .

  The present invention is also applicable to a deoxygenated water supply system for supplying deoxygenated water to a deoxygenated water demand location other than a boiler.

1 is a system diagram showing a deoxygenated water supply system according to an embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Supply water tank 2 Supply pipe 3 Deoxygenation apparatus 4 Water intake pipe 5 Water supply tank 6 Water supply pipe 7 Communication pipe 8 Water supply pipe

Claims (1)

A makeup water tank to which makeup water is supplied at a flow rate D (m ³ / hr) from a makeup water source;
A deoxygenation device in which water is supplied at a flow rate E (m ³ / hr) from the makeup water tank;
A water supply tank to which deoxygenated water is supplied from the deoxygenation device via a water supply pipe;
Communicating means for communicating the lower portions of the makeup tank and the water tank;
In a deoxygenated water supply system having a water supply pipe for supplying deoxygenated water from the water supply pipe or the water tank toward a deoxygenated water demand point,
B (m ³ / hr) is the expected maximum water supply to the deoxygenated water demand point,
Let the average horizontal cross-sectional area of the makeup tank be S ₁ (m ² ),
A deoxygenated water supply system characterized in that when the average horizontal cross-sectional area of the water tank is S ₂ (m ² ), the value of A defined by the following equation is always positive: .
A = (EB) + [S ₂ / (S ₁ + S ₂ )] · (BD)

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