JP4983069B2 - Pure water supply boiler water system treatment method and treatment apparatus - Google Patents

Description

The present invention relates to a pure water feed boiler water treatment method and treatment apparatus, and particularly to a boiler water treatment using a neutralizing amine (excluding ammonia) as a pH adjuster for water supply and condensate in an aqueous system containing a copper-based material. The present invention relates to a method and a processing apparatus.

Conventionally, the pH control of boiler water feed water has been measured with a pH meter by reducing the sample water extracted from the feed water system to atmospheric pressure, cooling to 25 ° C. so that it falls within the control range defined in JISB8223.

On the other hand, hydrazine is added to the water supply, especially for commercial thermal power generation, and ammonia is generated by thermal decomposition in the boiler, and this ammonia is transferred to the condensate system to supply water and condensate.
To adjust H and control the pH, a method has been proposed in which the electrical conductivity meter is used together with a pH meter to measure the electrical conductivity of condensate, and the amount of hydrazine added is converted into pH.
Japanese Patent Publication No. 63-54438

However, the measured value by the pH meter is easily affected by fluctuations in the sample water temperature.
The pH meter electrode is easily soiled and easily affected. In addition, it is difficult to obtain an accurate value because the electrode itself is easily deteriorated. In other words, the pH meter measurement is performed after the degree of degradation of the pH meter is ascertained and properly updated, and the pH meter electrode is routinely maintained and calibrated, and the temperature of the sample water is accurately managed at 25 ° C. If not, it is difficult to obtain an accurate pH value.

On the other hand, in industrial private power generation boilers, etc., copper-based materials are frequently used in the piping of water supply systems and condensers. Since ammonia is highly corrosive to copper, ammonia as a water supply / condensation system pH adjuster is used. Other neutralizing amines are used.

When this neutralizing amine is used, if it is attempted to control the pH by measuring the electrical conductivity in the above-mentioned known example, the neutralizing amine is partially thermally decomposed by the steam temperature in the boiler system, and ammonia or carbon dioxide Organic acids are generated. As a result, the electrical conductivity of the water supply increases, the dosage of neutralizing amine is more than necessary, and may exceed the management standard. In that state, p
Even if converted to H, there is a problem that the relationship between the pH and the electrical conductivity is not obtained, compared to the case where the ammonia is simply contained.

Furthermore, in industrial private power generation boilers, the generated steam is used not only for driving turbines for power generation, but also for heating and processes in factory processes, and the resulting condensed water is recovered and reused for feed water at a high rate. Bringing in contaminants such as carbon dioxide and organic matter, the electrical conductivity of the water supply will increase, deviating from the control standards as described above, and the relationship between pH and electrical conductivity will deviate from the theoretical curve of each neutralizing amine. There was also a problem to say.

For the above reasons, in the case of industrial self-powered boilers, when neutralizing amine is used, a method for controlling pH by measuring electric conductivity has not been studied. Well,
The method of controlling the addition amount of neutralizing amines other than ammonia itself using the measurement result of electric conductivity has not been studied.

In the pure water feed boiler water system for reusing condensate, the present invention provides a neutralizing amine (in the case of managing the water system without causing the problem of corrosion of the copper-based material used in at least a part of the piping system. And providing a pure water feed boiler water system treatment method and a treatment apparatus therefor that can determine the addition amount of the neutralizing amine by measuring the electrical conductivity of the feed water. It is the purpose.

The pure water feed boiler water system treatment method of the present invention (Claim 1) is a pure water feed boiler water system in which a copper-based material is used for a feed water system or a condensate system pipe and the condensate is deaerated and then supplied together with makeup water. In a method of adding a neutralizing amine (excluding ammonia) as a pH adjuster for water supply / condensate, a part of the degassed water is sampled to measure the electrical conductivity, and based on the result, determines the amount of neutralizing amine, water flow after the cation exchange resin column with water sampling a portion of the feed water deaerated Furthermore, by measuring the acid electric conductivity, the dissolved amount of impurities This is a pure water supply boiler water treatment method that can be operated without affecting the amount of neutralizing amine added by removing impurities out of the system when a certain value is exceeded.

The present invention (Claim 2) is a pure water feed boiler water treatment method in which a remarkable effect is obtained by using a specific amine whose neutralizing amine is alkanolamine, morpholine or aliphatic cyclic amine.

The present invention (Claim 3 ) includes a boiler, a steam pipe from the boiler, a condenser, a condensate return pipe, a water supply tank equipped with pure water supply means, a deaeration means, and a pH adjuster for water supply / condensate A boiler water treatment system including a chemical injection device for adding neutralizing amine (excluding ammonia) and a feed water system equipped with a flow meter, and at least part of the feed water system or condensate system pipe A material is used, and means for collecting a part of the degassed water supply, means for measuring electric conductivity, and the amount of the neutralizing amine added are determined based on the measured electric conductivity. And a calculation unit for performing deaeration, and an acid electrical conductivity measuring means for passing a part of the sampled feed water after passing through the cation exchange resin tower to the means for measuring the acid electrical conductivity. It is a water supply boiler water system processing apparatus.

Moreover, this invention (Claim 4 ) is a pure water supply boiler water-system processing apparatus whose neutralizing amine is alkanolamine, morpholine, or an aliphatic cyclic amine.

According to the present invention, even if the steam is sent for heating or the process of the factory process and the condensate recovered as condensed water is used again as feed water, the neutralizing amine (except for ammonia) is used. Makes it possible to accurately measure the electrical conductivity of water supply, and the difference between the pH of neutralizing amine and the theoretical curve of electrical conductivity is small, and it is more accurate and easier to measure than the method of directly measuring pH. It becomes. As a result, an amount of neutralizing amine (excluding ammonia) that can always maintain the appropriate electrical conductivity and pH of the feed water is added to the boiler water system, and a satisfactory operation can be performed. In addition, since the electrode structure of the electric conductivity meter is simple and does not easily deteriorate and is resistant to dirt, an accurate electric conductivity and pH value can be obtained by temperature correction and conversion as long as no significant impurities are mixed.

Embodiments of the pure water feed boiler water system processing method and processing apparatus of the present invention will be described in detail below.

FIG. 1 is a view for explaining a water system including an industrial private power generation boiler to which the method of the present invention is applied.

The boiler water system shown in FIG. 1 includes a boiler 1, a steam pipe 2, a steam turbine 3, a factory process 4,
A condenser 5, a water supply tank 6 having a pure water make-up water adding means, a condensate polisher 7, a deaerator 8, a flow meter 10, a pH adjusting agent adding means 11 for water supply / condensate, an economizer 9, a condenser, And condensate return piping for returning the condensate from the factory process to the water tank. Moreover, it has the electrical conductivity measurement means of the water supply shown in FIG.

Steam produced in the boiler 1 is sent to a steam turbine 3 as a load through a steam pipe 2 to generate electricity. Then, a part of the steam is sent to the factory process 4 side and used for heating and processing. The steam that has come out of the steam turbine 3 is condensed in the condenser 5 and sent to the water tank 6. On the other hand, from the factory process 4 side, the used steam becomes condensate and is purified by a condensate polisher 7 made of an ion exchange resin, and then sent to the same water tank 6 as described above.

If necessary, the water (water supply) from the water supply tank 6 to which pure water has been added as makeup water is then sent to the deaerator 8 where the dissolved gas contained in the water supply is separated, and then the economizer 9 Water is supplied to the boiler 1 via

In such an industrial private power generation boiler water system, a copper-based material is frequently used for at least a part of the piping of a water supply system or a condenser from the viewpoint of economy.

Ammonia, which has been conventionally used as a pH adjuster for water supply and condensate, is relatively corrosive to copper-based materials in systems using such copper-based materials, and may cause corrosion problems. It is difficult to use. Therefore, in the present invention, neutralizing amine (excluding ammonia) is used. Examples of such a neutralizing amine include aliphatic cyclic amines such as cyclohexylamine, monoethanolamine, alkanolamines such as 2-aminomethyl-1-propanol, and morpholine.

Among them, those having high thermal stability are preferable in order to reduce the influence of decomposition products on the quality of feed water, for example, morpholine, cyclohexylamine and monoethanolamine are preferable.

  Next, the electrical conductivity measurement method used in the present invention will be described with reference to FIG.

In FIG. 1, a part of the feed water (sample water) extracted from the deaerator is first sent to the cooler 12 and cooled to room temperature (25 ° C.). Next, the sample is transferred to a measuring instrument 13 having a thermometer and an electrode for measuring electric conductivity, where the temperature and electric conductivity are measured. Thermometer data is used for correction when it is different from 25 ° C. The sample water after measurement may be discarded or returned to the water tank.

  A signal obtained as a result of the measurement is sent to the calculation unit 21.

In the calculation unit 21, when the temperature is not 25 ° C., the electric conductivity is calculated by the electric conductivity correcting means 22.
Temperature correction. Since the electrical conductivity of the feed water detected in this way is pure water feed, it mainly represents the amount of residual neutralizing amine in the feed water.

In the present invention, the electrical conductivity data may be used as it is. However, if it is more convenient to convert the electrical conductivity data into pH display due to JIS or the like, the electrical conductivity data is converted into the pH conversion calculation means 23.
And converted to a pH value.

The obtained corrected electrical conductivity data and converted pH data are displayed on the electrical conductivity display means 25 and the pH value display means 24 if necessary. If necessary, these data can be recorded as accumulated data over time (not shown).

On the other hand, the obtained electrical conductivity data or pH data is sent to the chemical liquid discharge amount calculating means 26. Therefore, first, those data are set values (usually 2 to 3 μS / cm in the case of electrical conductivity).
In the case of pH, about 9.2 to 9.3), in order to increase the electric conductivity and pH, the amount of neutralizing amine added is increased to lower the flow rate from the flow meter 10 of FIG. The addition amount is calculated together with the data, and a signal is sent to the chemical injection device 11 of FIG. 1 to increase the addition amount of the neutralizing amine.

As such a chemical injection device, an arbitrary device such as a device capable of adjusting the pump stroke length, a device capable of adjusting the opening degree of the valve, a device capable of adjusting the rotation speed of the motor, or the like can be used.

If the obtained data is higher than the set value, a signal for reducing the dose is sent to the drug injection device 11. Thus, it is preferable to maintain the state where the medicine injection itself is always performed.

In the present invention, a neutralizing amine having a high thermal stability is preferably used. However, if the operation is continued, an organic acid which is a thermal decomposition product of the neutralizing amine gradually accumulates. Conductivity data tends to increase. Based on the electrical conductivity data of the feed water as it is, the added amount of neutralizing amine increases, and the electrical conductivity and pH of the feed water exceed the control values, so organic acids as such impurities are removed. It is preferable.

In the present invention, the acid conductivity is further measured as a specific means.

That is, in FIG. 2, a measuring instrument (flow cell) having an electrode for measuring acid electrical conductivity after part of the cooled sample water is collected and sent to the hydrogen cation exchange resin column 14.
15 As the acid electrical conductivity meter, the same type of electrode as the above electrical conductivity meter can be adopted.

The acid electrical conductivity thus obtained is displayed on the acid electrical conductivity display means 27. Alternatively, the warning means 28 may be adopted instead of the display.

The acid electrical conductivity indicates the amount of hydrogen ions proportional to the amount of organic acid in the sample water, so when this value reaches a set value, for example, 0.1 μS / cm, the amount of organic acid increases and affects the electrical conductivity. Therefore, a part of boiler water is blown out of the boiler water system to reduce the amount of organic acid in the boiler water.

As a method for reducing impurities, a method of bringing the feed water into contact with an anion exchange resin, etc. can be adopted in addition to the above-mentioned method by blowing, and any known organic acid removing method can be adopted.

Hereinafter, the present invention will be described more specifically with reference to test examples , reference examples, and examples.
(Test example)
In the pure water feed boiler water system using cyclohexylamine as the neutralizing amine and reusing condensate as feed water, using the apparatus shown in FIGS. Tested.

The boiler used was a natural circulation boiler, and the operating pressure was 12 MPa. Further, the normal steam amount was set to 70 to 140 t / h.

Pure water obtained by bringing industrial water into contact with mixed-bed ion exchange resin as feed water is used. The amount of cyclohexylamine added to the feed water is 0.4 to 1.5 mg / l. The amount was varied according to the variation of the amount.

A part of the feed water that has passed through the deaerator is drawn out, taken out as sample water, cooled to 25 ° C., and then supplied to a measuring instrument having an electric conductivity meter with a thermometer to measure the electrical conductivity at 25 ° C. did. On the other hand, the pH of the sample water was measured with a calibrated pH meter. When the relationship between the electrical conductivity and pH was determined, the results shown in FIG. 3 were obtained.

From this, it can be seen that in the neutralizing amine used in the present invention, the electrical conductivity and pH are in a certain relational expression.

( Reference example )
The test was performed using the apparatus used in the test example as it was. Since a calibration curve was obtained in the test example, the electrical conductivity of the feed water at the deaerator outlet was controlled to 2.3 μS / cm or the pH conversion value was 9.2 (= set value).

The operation was continued for one month, and the electric conductivity of the water supply was measured every 3 hours. When the electric conductivity was lower than the set value, the amount of cyclohexylamine added was increased. Moreover, when it became higher than the set value, the addition amount was reduced.

Thus, the boiler water system could be operated without any problems for one month by the method of the present invention.

(Example 1 )
In addition to the apparatus used in the reference example , a measuring device (flow cell) having a hydrogen cation exchange resin column and an acid conductivity meter was further provided, and a part of the test water was passed therethrough.

After the operation for one month as described in the above reference example , the above device was further added and the operation was continued for another month.

On the 40th day, an increasing tendency was observed in the electric conductivity of the water supply, and the acid electric conductivity was 0.1 μS / c.
Since m was reached, the opening degree of the boiler water blow valve was adjusted to increase the blow amount. When this was continued and the acid conductivity was measured again 6 hours later, it was less than 0.1 μS / cm, so the opening of the blow valve was restored. Meanwhile, the electrical conductivity of the water supply was maintained at its original level.

From the above, it can be seen that the method of the present invention is an excellent boiler water system operation method.

It is a figure for demonstrating the water system containing the general industrial private power generation boiler with which this invention is applied. The electric conductivity measuring method of this invention is shown. The result of the test example of this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boiler 3 Above-mentioned turbine 5 Condenser 8 Deaerator 11 Chemical injection device 12 Cooler 13 Electrical conductivity measuring device 14 Hydrogen type cation exchange resin column 15 Acid electric conductivity measuring device 21 Calculation part

Claims (4)

Copper-based material is used for at least a part of the water supply system or condensate piping, and neutralized amine as a pH adjuster for water supply and condensate in a pure water supply boiler water system in which the condensate is deaerated and then supplied together with makeup water In the method of adding (excluding ammonia),
A portion of the degassed feed water is sampled and the electrical conductivity is measured. Based on the result, the amount of the neutralizing amine is determined, and a part of the degassed feed water is sampled. Then, after passing the water through the cation exchange resin tower, the acid electrical conductivity is measured, and the pure water feed boiler water system treatment method.   2. The pure water feed boiler water treatment method according to claim 1, wherein the neutralizing amine is an alkanolamine, morpholine or an aliphatic cyclic amine.   Neutralizing amine (excluding ammonia) ), A boiler water system treatment device including a water supply system equipped with a flow meter, and a copper-based material is used for at least part of the water supply system or condensate system piping, and deaeration Means for collecting a part of the subsequent water supply, means for measuring the electrical conductivity, a calculation unit for determining the amount of the neutralizing amine added based on the measured electrical conductivity, and after deaeration A pure water feed boiler water treatment system comprising: acid electrical conductivity measurement means for passing a part of collected feed water to a means for measuring acid electrical conductivity after passing through a cation exchange resin tower. Neutralizing amine according to claim 3, pure water water boiler water treatment apparatus according to claim 3, wherein an alkanolamine, morpholine or aliphatic cyclic amine.

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