JPH06280505A - Application method for ammonia type condensate demineralizer - Google Patents

Abstract

PURPOSE:To substantially dispense with regeneration of ion exchange resin by introducing water subjected to clad-removal and filtration to a mixed resin layer of cation exchange resin and anion exchange resin, and succeeding water introduction without regenerating the mixed resin layer in the case that density of impurity ion other than sodium ion is not more than a reference value. CONSTITUTION:Condensate subjected to clad-removal treatment by means of hollow filtration film devices 71, 72 is fed to water columns 1, 2, 3 each containing cation exchange resin and anion exchange resin. Part of water at an inlet for condensate and outlet of each water bath is flowed to an ion chromatography device 5 through proper changeover by means of a water changeover means. Ions of sodium, chloride, sulfric acid are substantially continuously measured. Operation of an ammonia type condensate demineralizer can be succeeded without re-operating the ion exchange resins at all by monitoring density if impurity ion contained in the condensate in the water columns, in the normal case that no sea water leaks. Leakage of sodium ion is thus reduced to minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating condensate of a power plant, particularly a thermal power plant, by an ammonia-type condensate desalination treatment method.

[0002]

2. Description of the Related Art In a power station, the steam after driving a power generation turbine is cooled to be condensed water, the condensed water is heated to be steam again, and the cycle of driving the power generation turbine again with this steam is repeated. Since the condensate circulated in the system is contaminated with various kinds of impurity ions and cladding, a condensate demineralizer is provided to remove them.

By the way, in recent thermal power plant facilities, a mixed ion exchange resin of an ammonia type strongly acidic cation exchange resin and an OH type strongly basic anion exchange resin is used without removing ammonium ions in the condensate. Ammonia-type condensate desalination treatment for removing other impurities is often adopted. This is lower in running cost than the so-called H-OH type condensate desalination method (method using a mixed ion exchange resin of H type strongly acidic cation exchange resin and OH type strongly basic anion exchange resin). It depends.

[0004] The general operation of this ammonia type condensate demineralization treatment method is to use a plurality of parallel water towers (condensate demineralizer towers) filled with mixed ion exchange resins for treating condensate, It is carried out by an apparatus consisting of a regeneration system for regenerating the mixed ion exchange resin in the water tower, and the mixed ion exchange resin layer of the NH ₄ type cation exchange resin and the OH type anion exchange resin in the water tower is used to reconstitute the water. Impurities ions of the clad are removed by the ion exchange action, and the clad is removed by the filtration action or the adsorption action, and the pressure loss increases due to the accumulation of the clad due to the use over time, or when the constant volume treatment is reached or Na leak occurs. In this case, the mixed ion-exchange resin is sent to the regeneration system for regeneration treatment.

The regeneration treatment is carried out, for example, by first thoroughly bubbling the mixed ion exchange resin sent to the regeneration tower to remove the clad by backwashing, and then by backwashing and precipitating the separated cation exchange resin layer. For the anion exchange resin layer, an acid regenerant (usually H ₂ SO ₄ ) is passed through the cation exchange resin layer, and an alkali regenerant (usually Na ₂ ) is passed through the anion exchange resin layer.
OH) is passed through to remove the impurity ions, and the H-type cation exchange resin after regeneration is treated with NH ₄ form by ammonium hydroxide contained in the condensate after the start of water passage. Is converted into ammonia-type condensate desalination treatment.

As described above, in the ammonium-type condensate desalination treatment method, ammonium ion leaked into the treated water due to a change with time from the ion-exchange resin mixed with the H-type cation-exchange resin is the treated raw water. Even if the amount becomes the same as that in water, it is characterized by continuing water passage and removing sodium ions and other impurities in the condensate.

When the transition of the actual treated water quality in the conventional ammonia-type condensate desalination treatment method in which the chemical regeneration of the ion-exchange resin is regularly performed is observed, it is found that this is the state shown in FIG. It has been known. That is, the H-type cation exchange resin and the OH-type anion exchange resin are operated for 2 to 5 days (H / OH operation), and the cation exchange resin is changed from H-type to NH _{4 type} (1-2 Day), then 20 to 2 with NH ₄ type cation exchange resin and OH type anion exchange resin
It is divided into 5 days of operation (NH ₄ / 0H operation).
If the amount of impurity ions in the condensate is very small,
H / OH operation period as can be seen from Figure 4 the leakage of sodium ions hardly, NH ₄ leaks f transition period sodium ions is maximized, sodium leakage gradually decreases the NH ₄ / OH operation period. In the condensate, chloride ions, sulfate ions, etc., which are anion components, are very small, so the consumption of the OH form of the anion exchange resin is almost zero as shown below, and there is very little leakage into the treated water. Sometimes it is not necessary to regenerate the anion exchange resin.

Anion component in condensate (usually) 1μ
g CaCO ₃ / liter or less Water flow rate for anion exchange resin 150 l / lR ・ hr (SV = 50 for total resin amount) Therefore, R-OH consumption (= adsorbed ion amount) for one year is as follows. Is.

[0009]

[Equation 1]

In the ammonia type condensate desalination treatment,
It is said that the cation exchange resin that is regenerated into the H form needs to be regenerated strictly. This is because if the cation exchange resin immediately after regeneration contains more than the specified amount of Na-type cation exchange resin, the leakage of sodium ions increases when the water passage of the water tower is resumed, and exceeds the specified value. It is said that the sodium fraction after regeneration (the mole fraction of Na-type exchange groups with respect to all exchange groups) must generally be 0.003 or less.

However, although it is theoretically possible to completely eliminate this sodium leakage in the early stage of regeneration, it is not easy to realize it in actual industrial scale implementation. The reason for this is that in the l-column regeneration method in which the upper layer anion exchange resin and the lower layer cation exchange resin separated by backwash are regenerated as they are, the regeneration waste liquid of the anion exchange resin is collected from the separation interface at the collector. There is a problem that the regeneration waste liquid containing sodium hydroxide comes into contact with the cation exchange resin when it is taken out, and both ion exchange resins are regenerated in separate columns.
In the tower regeneration method, there is a problem that a small amount of the cation exchange resin is mixed in the transferred anion exchange resin and the sodium hydroxide solution as a regenerant comes into contact therewith. In addition, a problem that a fine cation exchange resin that cannot be backwashed and separated comes into contact with a sodium hydroxide solution is common to both methods.

Therefore, various ideas have been proposed in the past for improving the above-mentioned problems.
Proposal to reduce contact of the regeneration waste liquid containing sodium hydroxide with the cation exchange resin near the separation interface by locating the collector in the anion exchange resin layer above the separation interface. In the two-column regeneration method, when the anion-exchange resin in the upper layer is transferred to another column after backwashing and separating, a small amount of anion-exchange resin is left above the separation boundary surface. There is a proposal to prevent the cation exchange resin from being mixed into the anion exchange resin transferred to the tower. In the two-column regeneration method, a method has also been proposed in which a small amount of anion exchange resin in the upper layer of the separation interface and a small amount of cation exchange resin in the lower layer of the separation interface are excluded from the regenerated resin.

Further, with respect to the problem that a fine cation exchange resin is present in the anion exchange resin, an ammonium hydroxide solution is passed through the anion exchange resin after regeneration of the anion exchange resin. A method of converting the fine cation exchange resin present therein from the Na form to the NH ₄ form, or when separating the mixed resin, the specific gravity separation is carried out with a concentrated sodium hydroxide solution having an intermediate specific gravity of both ion exchange resins. Methods have also been proposed.

However, all of these proposed methods, which have been devised, are partially implemented industrially, but due to various reasons such as the problem of treatment of recycled waste liquid and large burden of equipment cost. Insufficient, and the proposal of the improved method and apparatus was called for.

As described above, the conventional operation of carrying out the ammonia-type condensate desalination treatment using the cation exchange resin and the anion exchange resin has many problems, and the improvement thereof has been demanded. .

As one of the operation methods of such an ammonia type condensate desalination treatment, a cation exchange resin is sampled by sampling a part of the resin at the time of regeneration when the pressure loss reaches a specified value. It has also been proposed to measure the Na fraction of water, and if the Na fraction is less than a specified value, restore the water flow state by simply removing the backwash clad (Japanese Patent Publication No. 10376/1993).
issue).

[0017]

However, the above-described sampling method has a problem in reliability in that whether or not the sampled resin accurately indicates the state of the resin in the water tower. That is, the amount of resin per tower of the condensate demineralizer is usually several thousand liters, and even if it is attempted to reproduce the state of the mixed resin in the water tower by using several liters of resin taken out from this, the timing of the taking out and This is because it is actually extremely difficult to satisfy a certain condition due to the deterioration state of the resin and the like, and there is a high possibility that the reproduction process is performed based on inappropriate measurement information.

Under the present circumstances, the present inventor has conducted extensive studies on the operation method of the ammonia type condensate desalination apparatus.

In the course of the research, the present inventor has shown that the conventional regeneration of the ion exchange resin is parallel to the clad removing operation by backwashing although the ion exchange resin still has the adsorption ability for impurity ions. In terms of the form, it means that the ion exchange resin, which originally does not need to be regenerated, was regenerated, and this regenerator regeneration rather caused the leakage of sodium ions at the initial stage of regeneration.

Therefore, the present inventor has made the present invention for the purpose of eliminating the above waste and proposing a new operation method capable of minimizing the leakage of sodium ions.

[0021]

The method of the present invention is characterized in that condensed water circulating in a power generation facility is passed through a mixed resin layer of a cation exchange resin and an anion exchange resin and desalted through the mixed resin layer. In the ammonia-type condensate desalination process, in which the presence of ammonium ions in the treated water is ignored, in the ammonia-type condensate desalination process, the filtered condensate obtained by filtering the hollow fiber membrane device to remove the clad is mixed as above. By passing through the resin layer, the concentration of impurity ions other than ammonium ions contained in the treated water that has passed through the mixed resin layer is below the control reference value It is about to continue water flow for desalination.

In order to measure the concentration of impurity ions in the condensate flowing in a water tower filled with an ion exchange resin, a branch pipe from a pipe through which these water flows is connected to an in-line chromatograph apparatus continuously or as needed. A method of measuring these impurity ions at regular intervals can be used, and examples of the measurement target include inlet water and outlet water of the water tower.

In addition, since the clad of the ion exchange resin of the water tower is removed by the hollow fiber filtration membrane device in the preceding stage, there is almost no accumulation of the clad, and therefore the problem that the pressure loss is substantially increased needs to be considered. But not double,
From the viewpoint of triple fail-safe, it is also preferable to appropriately adopt a conventionally known method to monitor the pressure loss state.

The hollow fiber filtration membrane device used in the method of the present invention is not particularly limited as long as it uses a filtration membrane suitable for removing the clad generated in the condensate of the power plant. it can.

According to the present invention, the clad is removed by the hollow fiber filtration membrane device in the preceding stage of the water tower, and the ion exchange is performed if the impurity ions are below the control standard value except when a seawater leak occurs. Since there is substantially no accumulation in the resin, there is no change in the exchange capacity of the ion exchange resin, and the ammonia type operation can be continued without stopping. When sodium leak occurs due to seawater leak, etc., it is the same as the conventional method to immediately stop the water flow through the water tower and carry out the regeneration operation with chemicals, but such a problem is practically nonexistent. Therefore, the present invention realizes continuous operation in which regeneration of the ion exchange resin is substantially unnecessary. It should be understood that the scrubbing, the replenishment of chemicals, etc. should be performed during the periodic inspection (eg, about once a year).

As the regenerating equipment prepared in advance, conventionally known equipment can be appropriately adopted.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be further described below with reference to the drawings.

FIG. 1 shows an example of the constitution of an ammonia type condensate demineralizer to which the method of the present invention is applied. In this figure, 1, 2 and 3 are filled with a cation exchange resin and an anion exchange resin. The water is a water tower, and the inlet water from which the clad has been removed through the hollow fiber filtration membrane devices 71 and 72 for removing the clad in the condensate sent from the condenser not shown is the branched inlet of the inlet water side pipe 4. Tubes 41,4
2, 43 are connected so as to be sent to the entrances of the water towers 1, 2, 3. Further, in this example, the inlet water side pipe 4 is further branched and connected to the ion chromatograph 5. In the hollow fiber filtration membrane devices 71 and 72, by switching a valve (not shown), it is possible to continue the water flow of the entire equipment by stopping the water flow of the clad which requires backwashing removal.

Further, the outlet pipes 61 of the water towers 1, 2, 3
62 and 63 are joined to the outlet side pipe 6 and connected to a boiler (not shown), and the outlet pipes 61 and 6 are also connected.
Reference numerals 2 and 63 are connected to the ion chromatography device 5, respectively.

With such a configuration, the condensate inlet water and a part of the outlet water of each water tower can be switched at appropriate times by the water passage switching means (not shown) to flow into the ion chromatograph 5. The chromatographic device 5 can measure sodium ions, chloride ions, and sulfate ions in the condensate water and the outlet water substantially continuously.

It should be noted that it is preferable to be able to measure and monitor the pressure loss that increases as the clad accumulates in the mixed ion exchange resin of each water tower, but it is not shown because it is not directly related to the present invention. To do. Similarly, a regeneration facility for regenerating the mixed ion exchange resin in the water tower may be preliminarily provided, but its illustration is omitted.

In the above structure, so-called seawater leak occurs after the water towers 1, 2 and 3 filled with the mixed ion exchange resin are started in the initial H-OH type and then shifted to the ammonia type operating state. As described above, unless otherwise specified, the Na fraction of the treated water from each water tower tends to gradually decrease.

Further, since the clad is removed by the hollow fiber filtration membrane devices 71 and 72, the clad does not accumulate in the mixed ion exchange resin layer, and therefore, in normal times, the regeneration operation of ammonia type is performed without performing any regeneration operation. Water treatment can continue.

Test Example In a thermal power plant, a column was installed as shown in FIG. Condensed water from which the clad was removed was passed through the column of No. 1 through a hollow fiber filtration membrane device, and Two
Condensate that did not pass through the hollow fiber filtration membrane device was passed through the column. In addition, No. The configuration of the hollow fiber filtration membrane device used in connection with the column of No. 1 is shown in Table 2 below. For the column No. 2, the mixed ion exchange resin was taken out of the column every 30 days, transferred to the regeneration column, scrubbed to remove the clad, and the ion exchange resin was regenerated under the conditions shown in Table 3 below.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

As described above, No. No. 1 column was continuously subjected to ammonia-type condensate demineralization treatment without performing regeneration operation. The two columns were regenerated every 30 days, and Na, Cl, and SO ₄ in the treated water of both columns were continuously monitored by an in-line ion chromatograph, and the results are shown in FIGS. 3 and 4.

As shown in FIG. 2, the pressure before and after the column was measured to measure the increase in the differential pressure of the ion exchange resin in the column, and the results are shown in FIGS. 5 and 6.

As can be seen from these results, No. 1
No differential pressure rise in the column (Fig. 5), and the treated water quality was 3
It can be seen that after 0 days, extremely good and stable water quality was obtained (Fig. 3). On the other hand, No. It can be seen that in the two columns, the water quality deteriorates every regeneration process (FIG. 4), and the state where the differential pressure gradually rises after the regeneration is repeated (FIG. 6).

[0041]

According to the present invention, by monitoring the impurity ion concentration of the condensate flowing through the water tower of the ammonia type condensate desalination apparatus, in the normal case where there is no seawater leak, the regeneration operation of the ion exchange resin is performed. The operation of ammonia-type condensate desalination can be continued without performing any operation, and the regeneration is a preliminary operation only in case of emergency. can get.

Further, since conventional drug delivery is not carried out,
It also has the effect of resolving the problem that the sodium content of the cation exchange resin increased during regeneration, and due to the impact on the surrounding environment, the regeneration wastewater is virtually eliminated in today's stricter nitrogen regulations. The effect of the present invention that can be achieved is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a schematic configuration of an ammonia-type condensate demineralizer which is suitable for carrying out the method of the present invention and in which an ion chromatograph is connected in-line.

FIG. 2 is a diagram showing a configuration of an apparatus of a test example in which the difference between the method of the present invention and the conventional method is tested.

FIG. 3 shows No. 1 in the test example. It is the figure which showed the time-dependent transition of the treated water quality of the condensate which appears at the time of normal operation in the ammonia type condensate demineralizer obtained by the column of No. 1.

FIG. 4 is a graph of No. 1 in the test example. It is the figure which showed the time-dependent transition of the treated water quality of the condensate which appears at the time of the operation | movement which performed the conventional regeneration process regularly obtained by the 2nd column.

FIG. 5 is a diagram showing changes in the differential pressure in the column when the operation of FIG. 3 is performed.

FIG. 6 is a diagram showing changes in the differential pressure in the column when the operation of FIG. 4 is performed.

[Explanation of symbols]

1, 2, 3: Water tower, 4: Inlet water side pipe, 5: Ion chromatographer, 6: Outlet side pipe, 41, 42, 43: Branch inlet pipe, 61, 62, 63: Outlet pipe, 71, 72 : Hollow fiber filtration membrane device.

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[Procedure amendment]

[Submission date] March 7, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

However, all of these proposed methods, which have been devised, are partially implemented industrially, but due to various reasons such as the problem of treatment of recycled waste liquid and large burden of equipment cost. insufficient, more improved methods, proposals of the device has been prompted.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

FIG. 2 shows the conditions of Table 1 below at a thermal power plant.
Install the column as shown in No. The condensate from which the clad was removed was passed through the column No. 1 through the hollow fiber filtration membrane device 81 , and Condensate that did not pass through the hollow fiber filtration membrane device was passed through the second column. In addition, No. The configuration of the hollow fiber filtration membrane device 81 used in connection with the column of No. 1 is shown in Table 2 below. For column 2, the mixed ion exchange resin was removed from the column every 30 days, transferred to a regeneration column, scrubbed to remove the clad, and Table 3 below.
The ion exchange resin was regenerated under the conditions of.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

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[Figure 1]

[Procedure amendment 4]

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[Fig. 2]

[Procedure Amendment 5]

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[Figure 6]

Claims (1)

[Claims] 1. Condensate circulated in a power generation facility is passed through a mixed resin layer of a cation exchange resin and an anion exchange resin, and the presence of ammonium ions in the treated water desalted through this mixed resin layer is ignored. In the ammonia-type condensate desalination treatment method in which condensate desalination treatment is performed while the condensate is filtered by a hollow fiber filtration membrane device to remove the clad, the treated condensate is passed through the mixed resin layer to obtain the mixed resin layer. Continuing water flow for condensate desalination without regenerating the mixed resin layer, provided that the concentration of impurity ions other than ammonium ions contained in the treated water that has passed through is less than the control standard value. A method for operating an ammonia-type condensate demineralizer, which is characterized by this.