JP2022038353A - Boiler water treatment device and treatment method - Google Patents

Abstract

To provide a boiler water treatment device and treatment method capable of stably supplying high-quality pure water to a boiler even in a case where TOC of raw water or pretreatment water is high concentration.SOLUTION: Industrial water is supplied to a boiler of a power generator 6 via a pretreatment device 1 and a pure water tank 3. Boiler blow water is desalted by a condensate desalting device 10 and returned to the pure water tank 3. Part of pure water in the pure water tank 3 is supplied to an RO device 18, and RO permeated water is returned to the pure water tank 3. Part of the boiler blow water is sent to a heat exchanger 16 via a branch pipe 22, and this water supply is heated by heat exchange with the water supply of the RO device 18.SELECTED DRAWING: Figure 1

Description

The present invention relates to an apparatus and a method for treating boiler-supplied pure water used in industry, power generation, and the like.

In boiler equipment used for industry, power generation, etc., pure water is produced from industrial water by pretreatment (aggregate solid-liquid separation and desalination treatment, etc.), and steam is generated by the boiler using this pure water. In such boiler equipment, it is common to collect boiler blow water, desalinate it, and then reuse it as pure water for the boiler (Patent Documents 1 to 3).

In the boiler equipment, the quality of the boiler water is controlled, and in particular, the electrical conductivity after treatment with ion exchange resin is controlled to prevent corrosion, but the raw water contains more TOC than expected. If it is (for example, TOC 200 ppb or more), or if the organic substance is excessively eluted from the ion exchange resin in the pretreatment pure water production, there is a concern that the electric conductivity exceeds the control value.

Japanese Unexamined Patent Publication No. 2007-268397 Japanese Unexamined Patent Publication No. 2010-216762 JP-A-2015-117913

2002 Boiler Yearbook, "Section 9 Impact on raw water / make-up water quality and boiler water quality in private power generation boilers and countermeasures"

An object of the present invention is to provide a boiler water treatment apparatus and a treatment method capable of stably supplying high quality pure water to a boiler even when the TOC of raw water or pretreated water is high.

The boiler water treatment device of the present invention is a pretreatment device that treats raw water to produce pure water, a pure water supply line that supplies pure water from the pretreatment device to the boiler, and concentrated wastewater from the boiler. A condensate demineralization means for desalting a certain boiler blow water, a boiler blow water introduction line for introducing the boiler blow water into the condensate demineralizing means, and a condensate demineralized water desalted by the condensate desalting means. In a boiler water treatment apparatus having a condensate demineralized water return line for returning the pure water to the pure water supply line, a part of pure water is taken out from the extraction unit from the pure water supply line and TOC removed by the TOC removing means. A TOC removal line that returns the treated water to the take-out part or the pure water supply line on the upstream side thereof, a heat exchanger provided on the upstream side of the TOC removal means in the TOC removal line, and the boiler blow water introduction. It is provided with a branch line that branches from the line and separates a part of the boiler blow water in the boiler blow water introduction line and introduces it into the heat exchanger, and is supplied to the TOC removing means by the heat exchanger. It is characterized in that water is heated by heat exchange with the boiler blow water.

The boiler water treatment apparatus of one aspect of the present invention includes a branch water return line that returns the boiler blow water that has passed through the heat exchanger to the downstream side of the branch point of the branch line in the boiler blow water introduction line.

The boiler water treatment apparatus according to one aspect of the present invention includes a measuring means for measuring the water temperature of pure water in the pure water supply line, and the boiler blow water in the branch line when the measured value of the measuring means is equal to or less than a predetermined value. It is provided with a branch flow control means for passing a part of the water or increasing the flow rate of the boiler blow water to the branch line.

In the boiler water treatment method of the present invention, raw water is treated with a pretreatment device to produce pure water, and the pure water from the pretreatment device is supplied to the boiler via a pure water supply line, and the pure water is supplied from the boiler. The exhaust steam is condensed and discharged from the boiler as boiler blow water, the boiler blow water is desalted by the condensate demineralizing means, and the condensate demineralized water desalted by the condensate desalting means is the pure water. In the boiler water treatment method of returning to the supply line, a part of pure water is taken out from the take-out part from the pure water supply line and TOC removal treatment is performed by the TOC removing means, and this treated water is taken out from the take-out part or the upstream side thereof. Return to the pure water supply line, and a part of the boiler blow water sent from the boiler to the condensate desalting means is separated, and the separated boiler blow water and the pure water supplied to the TOC removing means are separated. It is characterized in that water is exchanged with water by a heat exchanger to heat the pure water.

In the boiler water treatment method of one aspect of the present invention, the boiler blow water that has passed through the heat exchanger is supplied to the condensate desalting means for desalting treatment.

In the boiler water treatment method of one aspect of the present invention, the water temperature of pure water in the pure water supply line is measured, and when the measured value is equal to or less than a predetermined value, a part of the boiler blow water is separated to obtain the heat. The flow rate of boiler blow water that exchanges heat with the pure water in the exchanger or exchanges heat with the pure water in the heat exchanger is increased.

In the present invention, the TOC removing means is not provided in the pure water supply line (main line) that supplies pure water from the pretreatment device to the boiler, but the TOC is removed in the TOC removing line (offline) branched from the pure water supply line. A removing means is provided. Therefore, the TOC removing means can be controlled separately from the pure water supply control in the pure water supply line (main line).
Moreover, since the water supply of the TOC removing means is heated by using the boiler blow water, the efficiency of the TOC removing means can be stably maintained. It is especially effective when the water temperature drops due to location and climate.

It is a flow figure of the boiler water treatment apparatus which concerns on embodiment of this invention. It is a flow chart of the boiler water treatment apparatus which concerns on another embodiment.

Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a flow chart of a boiler water treatment device according to the first embodiment. The industrial water (industrial water) as raw water is pretreated by the pretreatment device 1 to become pure water, and is introduced into the pure water tank 3 via the pipe 2. The pure water in the pure water tank 3 is supplied to the boiler of the power generation device 6 such as the IPP power generation device via the pipe 5 having the pump 4. In this embodiment, the pure water supply line includes a pipe 2, a pure water tank 3, a pump 4, and a pipe 5. The boiler blow water generated in the boiler of the power generation device 6 is introduced into the condensate desalting device 10 as a desalting means via an introduction line having a pipe 7, a pressure adjusting means 24, a cooling means 8 and a pipe 9, and demineralized. It is salted.

In this embodiment, the condensate desalting apparatus 10 comprises a reverse osmosis membrane separating apparatus (RO apparatus) 11 and 12 arranged in a plurality of stages (two stages in this embodiment) in series, and an electric desalting apparatus 13. Have. The boiler blow water is desalted by RO treatment and electrosalting treatment to become pure water, and is returned to the pure water tank 3 via the pipe 14.

A TOC removal line is provided in order to take out a part of the pure water in the pure water tank 3 and perform a TOC removal treatment and a desalination treatment. That is, the pure water in the pure water tank 3 is supplied to the RO device 18 via the pipe 15, the heat exchanger 16, and the pump 17, and the RO permeated water is returned to the pure water tank 3 via the pipe 19. RO concentrated water is discharged to the outside of the system.

The heat exchanger 16 is for heating the pure water supplied from the pure water tank 3 to the RO device 18, and the high temperature fluid side thereof is from the upstream side of the pressure adjusting means 24 of the pipe 7 as a branch line. High-temperature boiler blow water is passed through the branched pipe 22. Since the high-temperature boiler blow water is supplied to the heat exchanger 16 in this way, the heating efficiency by heat exchange is high. The boiler blow water that has passed through the high temperature fluid side of the heat exchanger 16 is returned to the downstream side of the pressure adjusting means 24 of the pipe 7 via the pipe 23. Examples of the pressure adjusting means 24 include a back pressure valve, an orifice, and the like.

The cooling means 8 is for lowering the temperature of the boiler blow water sent to the condensate desalting device 10.

In this boiler water treatment device, the water quality of the pure water in the pure water tank 3 is determined by RO-treating the pure water in the pure water tank 3 with the RO device 18 by operating the pump 17 when necessary. Can be maintained in range.

Further, the RO processing efficiency can be increased by heating the pure water supplied to the RO device 18 with the heat exchanger 16. Further, when the RO permeated water having a high temperature flows into the pure water tank 3, the water temperature in the pure water tank 3 becomes high, and the load of heating the pure water on the boiler of the power generation device 6 can be reduced.

Although the pipe 15 is connected to the pure water tank 3 in FIG. 1, the pipe 15 may be connected to the pipe 5 on the downstream side of the pure water tank 3.

FIG. 2 is a flow chart of the boiler water treatment device according to the second embodiment, and as a TOC removing device for maintaining the water quality of pure water in the pure water tank 3, UV (ultraviolet rays) is used instead of the RO device 18. An oxidizing device 25 and an ion exchange device 26 are installed. As the ion exchange resin, it is preferable to use an anion exchange resin or a mixed bed resin. In the UV oxidizing device (for example, low pressure UV oxidizing device) 25, UV is irradiated to the water to be treated (pure water from the pure water tank 3) to decompose organic substances into organic acids and even CO ₂ . Organic acids, CO ₂ , etc. generated by decomposition are removed by the ion exchange device 26 in the subsequent stage. Pure water having a low organic substance concentration that has passed through the ion exchange device 26 is returned from the pipe 19 to the pure water tank 3.

In FIG. 2, the other configurations are the same as those in FIG. 1, and the same reference numerals indicate the same parts.

FIGS. 1 and 2 are examples of the present invention, and the present invention may be in a form other than those shown in the drawings. For example, in FIGS. 1 and 2, the boiler blow water cooled by the heat exchanger 16 is returned to the pipe 7 via the pipe 23, but the condensate desalting device 10 or the pipe 9 on the upstream side thereof, the pretreatment device. It may be returned to 1 or the raw water pipe or raw water tank on the upstream side thereof. When the water is returned to the pipe 7 as shown in FIGS. 1 and 2, the temperature of the high temperature boiler blow water is lowered and the load on the cooling means 8 can be reduced, so that the boiler blow water can be easily recovered.

Suitable examples, functions, and the like of the constituent devices of the boiler water treatment device of FIGS. 1 and 2 will be described below.

(1) Pretreatment device 1
The pretreatment device 1 sequentially performs agglomeration treatment, solid-liquid separation (precipitation separation, pressurized levitation separation, etc.), and double-layer filtration on raw water such as industrial water (city water, groundwater, etc.) and then removes the raw water. Pure water is produced by performing salt treatment (treatment with a cation exchange resin tower, a decarbonation tower, an anion exchange resin tower, a mixed bed resin tower, an electric desalination device, etc.).

(2) Pure water tank 3
In the pure water tank 3, the pure water produced by the pretreatment is stored, and the water quality and the amount of water are adjusted.

(3) TOC removing means When the TOC concentration contained in raw water such as industrial water is high, it may be difficult to reduce the TOC concentration to a predetermined value or less (for example, less than 100 ppb) by pretreatment. If the TOC concentration is 100 ppb or more, the burden on the boiler will increase and there is a concern that failure will occur in the future. In addition, the water temperature fluctuates depending on the season and climate (for example, 5 to 35 ° C). When the water temperature becomes 15 ° C or lower, the burden on the boiler for power generation becomes large and the amount of fuel used increases.

Therefore, the RO device 18 separates the pure water from the pure water tank 3 constituting the pure water supply line so that the TOC of the pure water in the pure water tank 3 is always maintained at a predetermined value or less (for example, 100 ppb or less). Or, the TOC removal process is performed by the TOC removing means including the UV oxidizing device 25 and the ion exchange device 26. By using a physicochemical means as the TOC removing means, it is possible to suppress the residual impurities in the treated water. By installing the TOC removing means in the TOC removing line branched from the pure water supply line, it is possible to perform control and maintenance different from those of the pure water supply line, for example, it is not affected by the water flow stoppage due to the backwashing of the membrane. In addition, TOC removing means can be easily installed in the existing boiler water supply device by additional work.

(4) As the power generation device 6, various devices such as an IPP power generation device equipped with a high-pressure boiler can be used.

(5) Boiler blow water discharge line-condensate desalting means-condensate return line Condensed water of boiler steam is generally at a high temperature (for example, 70 to 97 ° C.), and is cooled after being discharged from the boiler as boiler blow water (for example, 70 to 97 ° C.). It is cooled to about 20 to 40 ° C. by a closed cooling tower, a heat exchanger, etc.) and then supplied to the condensate desalting device 10.

In FIGS. 1 and 2, the condensate desalting apparatus 10 exemplifies in-series two-stage RO treatment → electrosalting, but is not particularly limited as long as it is a physicochemical means capable of desalting treatment.

(6) Cooling means 8
As shown in FIG. 1, a heat exchanger for reducing the temperature is arranged in front of the boiler blow water supply line of the condensate desalting apparatus 10. When the RO device 18 is used as the TOC removing means, RO concentrated water at about room temperature (5 to 35 ° C.) is discharged.

(7) Heat exchanger 16
When the water temperature of the pure water tank 3 tends to drop to a predetermined value or less (for example, 15 ° C. or less), the boiler blow water is separated and heat exchanged with pure water by the heat exchanger 16 to heat the water. This makes it possible to efficiently remove the TOC by the TOC removing means. Further, if the water temperature of the pure water tank 3 is maintained at, for example, 20 to 35 ° C., the burden on the high-pressure boiler of the IPP power generation facility can be reduced.

A valve is provided in the pipe 22, and the water temperature in the pure water supply line (pipe 2, pure water tank 3, pipe 5, etc.) and the TOC removal line (pipe 15, 19, etc.) is measured, and the measured value is measured. When the temperature becomes low below a predetermined value, the valve may be switched so as to supply a part of the boiler blow water from the pipe 7 to the pipe 22, and the temperature may be controlled by this mechanism. Further, the flow rate may be controlled so as to adjust the branch flow rate to the pipe 22 based on the measured water temperature value. This is preferable because the water temperature of the boiler feed water is maintained within a predetermined range and the load on the boiler is maintained within a certain range.

[Example 1]
Chiba Prefecture industrial water (TOC concentration 2 to 3 ppm; water temperature 10 ° C.) was treated by the boiler water treatment device of FIG. 1, water was supplied to the boiler of the IPP power generation device 6, and boiler blow water was recovered. In the pretreatment apparatus 1, pure water was produced by performing agglomeration treatment, pressure levitation separation, two-layer filtration, two-bed three-tower type ion exchange (cation exchange, decarbonation, anion exchange). The main conditions are shown below and in Table 1. The results are shown in Table 1.

Average supply of industrial water (average flow rate of pipe 2): 35m ³ / hr
Pure water tank 3 Volume: 400m ³
Average water supply to IPP power generation boiler (Piping 5 average flow rate): 35m ³ / hr
Boiler blow water average flow rate (pipe 7 average flow rate): 10-12m ³ / hr
RO device 18 average water supply amount (pipe 15 average flow rate): 34m ³ / hr
RO device 18 average permeation amount (pipe 19 average flow rate): 30m ³ / hr
Cooling means 8 Water supply average flow rate: 10-12m ³ / hr
Branch blow water average flow rate (pipe 22 average flow rate): 5 to 15 m ³ / hr

[Example 2]
The operation was performed under the same conditions as in Example 1 except that the boiler water treatment device was the boiler water treatment device shown in FIG. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, the operation was performed under the same conditions as in Example 1 except that the amount of boiler blow water supplied to the heat exchanger 16 (flow rate of the pipe 22) was set to 0 m ³ / hr (water flow stop). The results are shown in Table 1.

As shown in Table 1, in Examples 1 and 2, the TOC concentration of the boiler feed water is lower, the temperature is higher, the load on the boiler is reduced, and the load on the boiler is reduced as compared with Comparative Example 1 in which the TOC removal line is not preheated. It was found that the load on the boiler in the subsequent stage was reduced. Further, in Examples 1 and 2, a part of the boiler blow water is used for preheating the pure water, and the cooled boiler blow water is returned, so that the water temperature of the boiler blow water introduced into the condensate desalting device (piping). It was confirmed that the water temperature of the pipe 7 after the condensate from 23) decreased, and the load on the cooling means 8 was reduced.

1 Pretreatment device 3 Pure water tank 6 Power generation device 8 Cooling means 10 Condenser desalination device 16 Heat exchanger 11, 12, 18 RO device 13 Electric desalination device 24 Pressure adjustment means 25 UV oxidation device 26 Ion exchange device

Claims (6)

A pretreatment device that treats raw water to produce pure water,
A pure water supply line that supplies pure water from the pretreatment device to the boiler,
A condensate desalting means for desalting the boiler blow water which is concentrated wastewater from the boiler, a boiler blow water introduction line for introducing the boiler blow water into the condensate desalting means, and the like.
In a boiler water treatment apparatus having a condensate demineralized water return line for returning condensate demineralized water desalted by the condensate desalting means to the pure water supply line.
A TOC removal line that takes out a part of pure water from the pure water supply line from the take-out part, performs TOC removal treatment by TOC removing means, and returns the treated water to the take-out part or the pure water supply line on the upstream side thereof. When,
A heat exchanger provided on the upstream side of the TOC removing means in the TOC removing line, and
It is provided with a branch line that branches from the boiler blow water introduction line, separates a part of the boiler blow water in the boiler blow water introduction line, and introduces it into the heat exchanger.
A boiler water treatment apparatus characterized in that pure water supplied to the TOC removing means is heated by heat exchange with the boiler blow water by the heat exchanger. The boiler water treatment apparatus according to claim 1 is provided with a branch water return line for returning the boiler blow water that has passed through the heat exchanger to the downstream side of the branch point of the branch line in the boiler blow water introduction line. .. In claim 1 or 2, a measuring means for measuring the water temperature of pure water in the pure water supply line and a part of the boiler blow water are passed through the branch line when the measured value of the measuring means is equal to or less than a predetermined value. A boiler water treatment apparatus comprising: a branch flow rate control means for watering or increasing the flow rate of the boiler blow water to the branch line. Raw water is treated with a pretreatment device to produce pure water,
Pure water from the pretreatment device is supplied to the boiler via the pure water supply line.
The exhaust steam from the boiler is condensed and discharged as boiler blow water from the boiler.
The boiler blow water is desalted by condensate desalting means.
In the boiler water treatment method in which the condensate demineralized water desalted by the condensate desalting means is returned to the pure water supply line.
A part of pure water is taken out from the pure water supply line from the pure water supply line, TOC removal treatment is performed by the TOC removing means, and the treated water is returned to the pure water supply line on the upstream side of the take-out part.
A part of the boiler blow water supplied from the boiler to the condensate desalting means is separated, and the separated boiler blow water and the pure water supplied to the TOC removing means are heat exchanged by a heat exchanger. A boiler water treatment method comprising heating the pure water. The boiler water treatment method according to claim 4, wherein the boiler blow water that has passed through the heat exchanger is supplied to the condensate desalting means for desalting treatment. In claim 4 or 5, the water temperature of pure water in the pure water supply line is measured, and when the measured value is equal to or less than a predetermined value, a part of the boiler blow water is separated and the pure water is subjected to the heat exchanger. A boiler water treatment method comprising increasing the flow rate of boiler blow water that exchanges heat with water or exchanges heat with pure water in the heat exchanger.

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