JP2010185655A - Method for inhibiting corrosion of boiler device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize the usage of a pH adjuster in inhibition of corrosion caused in a boiler device by the use of the pH adjuster. <P>SOLUTION: The method for inhibiting corrosion in a boiler 2 using the pH adjuster in the boiler device 1 includes a measurement step of measuring a total carbonic acid concentration of supply water in a water supply passage 10 of a water supply part 3 at fixed time intervals; a feed rate determination step of determining, based on the measurement result in the measuring step, the feed rate of the pH adjuster; and a pH adjuster supply step of supplying, based on the feed rate determined in the feed rate determination step, the pH adjuster to the water supply part 3. The measurement interval in the measuring step can be adjusted according to the measurement value of total carbonic acid. In the feed rate determination step, further, an optimum feed rate to inhibit the corrosion of the boiler 2 is calculated considering alkali generated from the supply water containing total carbonic acid through thermal decomposition, whereby the feed rate of the pH adjuster can be adjusted by eliminating the waste of feed of the pH adjuster. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for inhibiting corrosion of a boiler device, and in particular, a boiler that heats feed water to generate steam, a water supply unit that supplies water to the boiler, and steam that supplies steam generated by the boiler to load equipment The present invention relates to a method for inhibiting corrosion in a boiler device including a supply unit.

  Boiler equipment piping, particularly heat transfer tubes made mainly of steel for generating steam from the boiler, may be damaged due to corrosion. This corrosion of the heat transfer tube is likely to occur when the pH of the boiler water is low. Usually, the feed water containing total carbonic acid in the boiler generates alkali by pyrolysis and raises the pH of the boiler water. Thereby, the pH of boiler water rises and the corrosion of a heat exchanger tube is suppressed. However, if the total carbonic acid concentration in the feed water is low, the pH of the boiler water does not rise so much, and corrosion progresses evenly on the inner surface portion of the heat transfer tube that is in contact with the boiler water, leading to a reduction in the thickness of the heat transfer tube. there is a possibility.

  For this reason, in order to suppress corrosion of the heat transfer tube, the pH of the boiler water is predicted from the concentration of total carbonic acid contained in the feed water. As a method for predicting the pH of boiler water, the total carbonic acid concentration of feed water is usually measured once and a pH adjuster is added accordingly. However, the quality of the feed water varies from day to day, and when the total carbonic acid concentration increases, the pH of the boiler water rises and the amount of pH adjuster added may be set in advance, although the amount of pH adjuster may be small. Therefore, the amount of pH adjuster added becomes excessive, and chemicals are wasted. On the contrary, when the total carbonic acid concentration is lowered, the pH of the boiler water is lowered and the pH adjusting agent is added in spite of having to increase the pH adjusting agent. There is a possibility that corrosion of the heat transfer tube will occur due to the insufficient amount of added.

  This invention exists in optimizing the usage-amount of a pH adjuster in suppressing the corrosion which generate | occur | produces in a boiler apparatus using a pH adjuster in view of the said subject.

  This invention was made in order to solve the said subject, The invention of Claim 1 is a boiler which heats feed water and produces | generates a steam, A water supply part which supplies feed water to this boiler, A boiler apparatus comprising: a steam supply unit that supplies steam generated by the boiler to a load device; and a method for suppressing corrosion in the boiler by using a pH adjuster, wherein water is supplied to the water supply unit at regular intervals. A measurement step for measuring the total carbonic acid concentration of the water supply in the road, a supply amount determination step for determining the supply amount of the pH adjuster each time based on the measurement result in this measurement step, and a determination in this supply amount determination step A pH adjusting agent supplying step for supplying a pH adjusting agent to the water supply unit based on the supplied amount, and the measurement interval in the measuring step can be adjusted according to the measured value of total carbonic acid. Cage Further, in the supply amount determination step, an optimum supply amount for suppressing corrosion of the boiler is calculated in consideration of alkali generated by thermal decomposition from the feed water containing total carbonic acid, and the supply amount of the pH adjusting agent is wasted. It is characterized in that the supply amount of the pH adjusting agent is adjustable so as to eliminate the above.

Furthermore, the invention according to claim 2 is a boiler that heats feed water to generate steam, a water supply unit that supplies water to the boiler, a steam supply unit that supplies steam generated by the boiler to a load device, A boiler apparatus comprising a condensate supply unit for supplying steam used in the load equipment as condensate to the water supply unit, and a method for suppressing corrosion in the boiler using a pH adjuster, for a certain period of time A measurement step for measuring the total carbonic acid concentration of the feed water in the water supply channel of the water supply unit every time, and a supply amount determination step for determining the supply amount of the pH adjuster each time based on the measurement result in this measurement step, A pH adjusting agent supplying step for supplying a pH adjusting agent to the water supply unit based on the supplying amount determined in the supplying amount determining step, and the measurement interval in the measuring step is a measured value of total carbonic acid. According In addition, in the supply amount determination step, an optimum supply amount is calculated to suppress corrosion of the boiler in consideration of alkali generated by thermal decomposition from feed water containing total carbonic acid, and pH It is characterized in that the supply amount of the pH adjusting agent can be adjusted so as to eliminate waste of the supply amount of the adjusting agent.

  According to this invention, in using the pH adjuster to suppress corrosion that occurs in the boiler apparatus, the amount of the pH adjuster used can be optimized.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic of the boiler apparatus applied to embodiment of this invention. The longitudinal cross-sectional schematic of the measuring apparatus used in the said boiler apparatus. FIG. 3 is a schematic vertical cross-sectional view of a reagent supply device portion that constitutes the measurement device as viewed from the III direction of FIG. The figure which shows schematic structure of the control apparatus part of the said measuring apparatus. The flowchart which shows the supply operation | movement process of the pH adjuster in the said boiler apparatus. The flowchart which shows the supply operation | movement process of the pH adjuster in the said boiler apparatus. The flowchart which shows the supply operation | movement process of the pH adjuster in other embodiment. The graph which showed notionally the determination table which measures a hydrogencarbonate ion concentration based on the transmittance | permeability of the light which passes a water supply sample. Schematic of the boiler apparatus in other embodiment.

  A boiler apparatus according to an embodiment of the present invention will be described with reference to FIG. In FIG. 1, a boiler device 1 includes a boiler 2 that heats feed water to generate steam, a water supply device 3 (an example of a water supply unit) that supplies feed water to the boiler 2, a load device 4 that uses steam, Steam piping 5 (an example of a steam supply unit) that supplies steam generated in the boiler 2 to the load device 4, a chemical supply device 6 that adds a pH adjuster to the water supply device 3, and total carbonic acid contained in the water supply It mainly comprises a measuring device 7 for measuring the concentration.

  In order to supply water to the boiler 2, the water supply device 3 supplies a water supply path 8 for make-up water, a water supply tank 9 for storing make-up water from the water supply path 8, and water supplied in the water supply tank 9. A water supply channel 10 for supplying to the boiler 2 is mainly provided (see FIG. 1). Here, the water injection path 8 includes a water softening device 11 and a deoxygenation device 12 in this order. The water softening device 11 replaces hardness components such as calcium ions and magnesium ions contained in makeup water with sodium ions and converts them into soft water. On the other hand, the deoxygenation device 12 mechanically removes dissolved oxygen contained in the makeup water. In addition, the water supply path 10 includes a water supply pump 13 that sends water to the boiler 2.

  The load device 4 is a load device in the boiler device 1 that performs required heat exchange using the steam from the boiler 2, and is connected to the downstream side of the steam pipe 5.

The drug supply device 6 mainly includes a drug tank 14 storing a pH adjuster and a drug supply path 15 communicating with the water supply path 10 in order to add a pH adjuster to the water supply apparatus 3. ing. The pH adjusting agent stored in the chemical tank 14 is particularly limited as long as it has a function of suppressing the occurrence and growth of corrosion in the heat transfer tube (not shown) of the boiler 2 by adjusting the pH. Although not intended, for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.

  On the other hand, the medicine supply path 15 includes a supply pump 16 that supplies the pH adjusting agent in the medicine tank 14 to the water supply path 10. The supply pump 16 is a metering pump capable of supplying a predetermined amount of pH adjusting agent to a certain amount of water that is moving toward the boiler 2 in the water supply channel 10.

  The measuring device 7 is provided in the measurement sample supply channel 17 in the water supply channel 10 in order to measure the total carbonic acid concentration contained in the water supply (see FIG. 1). Here, the total carbonic acid includes three forms of carbonic acid, hydrogen carbonate ion, and carbonate ion, and almost exists as hydrogen carbonate ion in the vicinity of neutrality. Therefore, in this embodiment, a case where the hydrogen carbonate ion concentration is measured will be described. When measuring the bicarbonate ion concentration, the measurement device 7 mainly includes a measurement cell 18, a measurement unit 19, a reagent supply device 20, and a control device 21, as shown in FIG.

  The measurement cell 18 is a transparent container in which, for example, an acrylic resin is formed in a cylindrical shape, and has an opening 22 at the top. A sample introduction path 23 connected to the measurement sample supply path 17 is provided on a side surface near the bottom of the measurement cell 18. The sample introduction path 23 includes a filter 24, a constant flow valve 25, and an electromagnetic valve 26 in order from the measurement sample supply path 17 side, and is supplied from the water supply path 10 through the measurement sample supply path 17. It is set so that water can be supplied into the measurement cell 18. A sample discharge path 27 for discharging the measurement sample to the outside is provided in the vicinity of the opening 22 at the side of the measurement cell 18.

  A stirring device 28 is provided at the bottom of the measurement cell 18. The stirring device 28 includes a stirring bar 29 and a stator 30. The stirrer 29 is rotatably arranged at the bottom of the measurement cell 18 and incorporates a magnet (not shown). The stator 30 is disposed outside the measurement cell 18 so as to surround the stirrer 29 and includes an electromagnetic induction coil (not shown). The electromagnetic induction coil is set to be supplied with current.

  The measurement unit 19 measures the transmitted light intensity of the water supply (hereinafter referred to as “water supply sample”) stored in the measurement cell 18, and the light emitter 31 facing the measurement cell 18. And a light receiving body 32. Here, the light emitter 31 is, for example, an LED, and the light receiver 32 is, for example, a phototransistor.

  The reagent supply device 20 is detachably disposed in the opening 22, and as shown in FIG. 3 (a longitudinal sectional view of the reagent supply device 20 viewed from the direction III in FIG. 2), a reagent cassette 33, A reagent cartridge 34 and a discharge device 35 are mainly provided. The reagent cassette 33 is detachably mounted by a mounting tool (not shown) so that the bottom portion maintains an airtight state in the opening 22. A slit 36 extending in the vertical direction is formed in the wall portion of the reagent cassette 33. Further, inside the reagent cassette 33, a pressing member 37 is mounted on the inner surface facing the slit 36 in the vertical direction.

The reagent cartridge 34 mainly includes a container 38 and a reagent storage body 39. The container 38 is mounted on the upper part of the reagent cartridge 34, and the upper part of the container 39 is accommodated in the container 38. The container 39 includes a storage unit 40 in which a reagent that changes color by reacting with bicarbonate ions (for example, methyl orange) and a buffer solution (for example, a phthalate buffer solution of pH 3.4) are stored, and the storage unit 40. And a discharge portion 41 for discharging the reagent and buffer solution therein. The discharge portion 41 is made of, for example, a fluororubber tube, extends from the storage portion 40, and includes a discharge nozzle 42 at the tip. The discharge part 41 extends in the vertical direction inside the reagent cartridge 34, and the discharge nozzle 42 is inserted into the measurement cell 18 from the opening 22. Here, the discharge nozzle 42 has a built-in check valve (not shown) that prevents the water supply sample in the measurement cell 18 from flowing backward.

  The discharge device 35 discharges the reagent and buffer stored in the storage unit 40, and mainly includes a rotary drive shaft 43, a drive arm 44, and a pressing roller 45 connected to a motor (not shown). I have. The rotation drive shaft 43 is disposed outside the slit 36 and can rotate counterclockwise in FIG. One end of the drive arm 44 is connected to the rotary drive shaft 43, and the pressing roller 45 is rotatably attached to the other end. The drive arm 44 can be rotated counterclockwise by the rotation of the rotary drive shaft 43 as shown by a two-dot chain line in FIG. It is set to be able to enter and exit from the reagent cassette 33.

  Here, the reagent supply device 20 employs substantially the same configuration as that of Patent No. 3186777 (title of the invention: liquid ejection device), which is the patent of the present applicant. Please refer.

  The control device 21 controls the operation of the measuring device 7 and mainly includes an arithmetic device 46 and an input / output port 47 as shown in FIG. The arithmetic device 46 includes a central control device 48 (hereinafter referred to as “CPU 48”), a read-only storage device 49 (hereinafter referred to as “ROM 49”) that stores an operation program of the control device 21, and a read / write operation. It mainly includes a possible storage device 50 (hereinafter referred to as “RAM 50”).

  On the other hand, on the input side of the input / output port 47, a switch 51 for inputting an operating condition and the like by the operator, the light receiving body 32 and the like are connected. Further, an LCD 52 for displaying measurement results, the light emitter 31, the electromagnetic valve 26, the stator 30, and a motor (reference numeral omitted) for driving the rotation drive shaft 43 are connected to the output side.

  In accordance with the operation program stored in the ROM 49, the control device 21 performs arithmetic processing while the arithmetic device 46 appropriately stores various information input via the input / output port 47 in the RAM 50, and stores the information The device 46 is set to transmit various operation commands to each member via the input / output port 47 based on the calculation result obtained there.

  Next, the operation of the boiler device 1 will be described, and a method for inhibiting corrosion of the boiler device 1 will be described. When operating the boiler device 1, makeup water is supplied from the water injection path 8 to the water supply tank 9, and this makeup water is stored in the water supply tank 9 as water supply to the boiler 2. Here, the stored water supply is the water treated by the water softening device 11 and the deoxygenation device 12, that is, deoxygenated soft water. Then, the water supply pump 13 is operated to supply water stored in the water supply tank 9 to the boiler 2 through the water supply passage 10.

The feed water supplied to the boiler 2 through the feed water channel 10 is stored in the boiler 2 as boiler water. Then, the boiler water stored in the boiler 2 is heated and gradually becomes steam. The generated steam is supplied to the load device 4 through the steam pipe 5. The steam supplied to the load device 4 is discarded after performing a desired heat exchange.

  By the way, the feed water supplied to the boiler 2 may contain bicarbonate ions. In this case, the feed water is heated in the boiler 2 to become steam, and the hydrogen carbonate ions generate alkali by thermal decomposition. The generated alkali increases the pH of the boiler water and suppresses the corrosion of the boiler 2. However, if the amount of generated alkali is small, the boiler 2 may be corroded, and the heat transfer tube of the boiler 2 may be thinned.

  Therefore, the boiler device 1 measures, by the measuring device 7, at regular intervals whether or not hydrogen carbonate ions in the feed water are equal to or higher than a preset value. And based on the measurement result in the said measuring apparatus 7, a pH adjuster is added from the said chemical | medical agent supply apparatus 6 to water supply. Hereinafter, this operation will be described in detail according to the operation flowchart shown in FIGS.

When the operation of the boiler device 1 is started, the program sets the elapsed time t of the internal timer of the control device 21 to zero (0) in step S1, and the elapsed time t is set to zero in the next step S2. It is determined whether or not a certain time t ₁ has been reached. When the elapsed time t reaches the predetermined time t ₁ , the program proceeds to step S3 and resets the elapsed time t to zero (0). Here, the fixed time t ₁ is usually about 0.1 to 24 hours.

  After step S3, the program proceeds to step S4, and a pre-cleaning process is performed in the measuring device 7. First, the water supply in the water supply path 10 flows from the sample introduction path 23 into the measurement cell 18 via the measurement sample supply path 17. At this time, impurities contained in the water supply are removed by the filter 24. Further, the flow rate of the feed water flowing into the measurement cell 18 is controlled by the constant flow valve 25. The feed water that continuously flows into the measurement cell 18 fills the measurement cell 18 and is continuously discharged from the sample discharge path 27 to the outside. At this time, an electromagnetic induction coil (not shown) of the stator 30 is energized, and a magnet (not shown) in the stirrer 29 receives a magnetic field generated thereby. As a result, the stirrer 29 in the measurement cell 18 rotates, and the feed water flowing into the measurement cell 18 is stirred. As a result, the measurement cell 18 is washed by the continuously flowing water.

  After the pre-cleaning process as described above, the program moves to step S5 and measures the bicarbonate ion concentration in the feed water (measuring process). Here, energization of the electromagnetic induction coil of the stator 30 is temporarily stopped, and the supply of water supply is also stopped. Thereby, the inflow of the water supply into the measurement cell 18 is cut off, and a predetermined amount of water supply is stored in the measurement cell 18 as a water supply sample up to the water level indicated by the one-dot chain line in FIG. Moreover, the front-end | tip part of the said discharge nozzle 42 will be located in the stored water supply sample. In this state, the measurement unit 19 is operated to irradiate light from the light emitter 31 toward the light receiver 32. Then, the transmitted light intensity (A) of the water supply sample is measured.

  Next, energization of the electromagnetic induction coil of the stator 30 is started, the rotation of the stirrer 29 is resumed, and the motor (not shown) of the discharge device 35 is driven to continue the rotation while the rotation is continued. The drive shaft 43 is rotated. As a result, the drive arm 44 rotates counterclockwise in FIG. 3, and accordingly, the pressing roller 45 handles the discharge portion 41 downward in cooperation with the pressing member 37. As a result, a fixed amount of reagents and buffer solutions stored in the storage unit 40 are injected into the water supply sample in the measurement cell 18. Then, when such rotational movement of the drive arm 44 is repeated a predetermined number of times, a constant amount of reagent and buffer solution are intermittently injected into the measurement cell 18 every time the drive arm 44 rotates. (Injection process). Therefore, the reagent and the buffer solution are gradually injected. In this way, the reagent and the buffer solution injected into the measurement cell 18 are dissolved in the feed water sample stirred by the rotation of the stirrer 29 to change the color of the feed water sample.

In the injection step as described above, the control device 21 continues the rotation of the stirrer 29, and the transmitted light intensity of the water supply sample (colored by the measurement unit 19 is gradually changed by the reagent and the buffer solution). B) is measured continuously. At this time, the control device 21 measures a change amount of a change in transmitted light intensity with an increase in the amount of reagent and buffer solution injected into the water supply sample (change amount measurement step). The amount of change in transmitted light intensity measured here is usually the difference (ΔB) in transmitted light intensity before and after a fixed amount of reagent and buffer solution are injected. For example, as shown in FIG. 8, the transmitted light intensity of the water supply sample gradually decreases according to the number of injections of the reagent and buffer solution (that is, the number of rotations of the drive arm 44). Here, when all of the bicarbonate ions in the water supply sample have reacted with the reagent and buffer solution injected before the Xth time, in the injection operation after the Xth time, more reagents and buffer solutions are injected. However, the discoloration of the water supply sample does not easily proceed, and the transmitted light intensity of the water supply sample does not easily change. That is, the difference (B ₁ −B ₂ , that is, ΔB) between the transmitted light intensity B ₁ after the Xth injection of the reagent and the buffer and the transmitted light intensity B ₂ after the X + 1th injection is small. Make a difference. Therefore, when ΔB becomes a predetermined amount or less, even if more reagent and buffer solution are injected into the water supply sample, the reagent and buffer solution are not involved in the reaction with bicarbonate ions in the water supply sample, It remains in the water supply sample as it is.

  Therefore, when the control device 21 determines that the ΔB has become equal to or less than a predetermined amount, the control device 21 stops the rotation operation of the drive arm 44. This stops additional injection of reagents and buffer into the feedwater sample. Subsequently, the control device 21 calculates a ratio (transmitted light intensity ratio: B / A) between the transmitted light intensity (B) of the water supply sample at that time and the transmitted light intensity (A) before the reagent and buffer solution are injected. Ask. Then, based on the calibration curve data of the transmitted light intensity ratio and the bicarbonate ion concentration prepared in advance, the control device 21 calculates the bicarbonate ion concentration in the water supply sample and displays the result on the LCD 52. .

  After the measurement process as described above, the program proceeds to step S6, and in this step S6, it is determined whether or not the bicarbonate ion concentration of the feed water sample is less than the set value. In the measurement process of step S5, when the bicarbonate ion concentration is measured to be a preset value, for example, less than 10 mg / liter, the program proceeds from step S6 to step S11, and the pH adjuster addition identification flag of the CPU 48 is determined. Whether or not is ON is determined. If the pH adjuster addition identification flag is on (ON), the program proceeds to step S14, and the pH adjuster addition amount adjusting step is performed.

  In this pH adjuster addition amount adjusting step, when the bicarbonate ion concentration measured in step S5 is different from the bicarbonate ion concentration measured in the previous step S5, in step S14, the program is based on the bicarbonate ion concentration. Since the supply pump 16 is operated, the amount of the pH adjusting agent added to the water supplied from the water supply channel 10 to the boiler 2 is changed.

  And a program transfers to step S15 and implements a post-cleaning process. Thereafter, in the cleaning process, the program supplies water while rotating the stirrer 29. Here, the feed water sample containing the reagent and the buffer stored in the measurement cell 18 is pushed out by the feed water newly flowing from the sample introduction path 23 and discharged from the sample discharge path 27 to the outside. As a result, the measurement cell 18 is cleaned by newly supplied water. After completion of step S15, the program returns to step S2.

  Conversely, when the pH adjuster addition identification flag is off (OFF), the program proceeds to step S12 and performs the pH adjuster addition step.

  In the pH adjusting agent adding step in step S <b> 12, the control device 21 operates the supply pump 16 of the medicine supply device 6 to supply the pH adjusting agent to the water supply channel 10. Thereby, a pH adjuster is added to the water supply which is passing through the water supply path 10 toward the boiler 2. Here, the control device 21 controls the operation of the supply pump 16 based on the bicarbonate ion concentration measured in step S5. More specifically, when the hydrogen carbonate ion concentration measured in step S5 is considerably lower than the preset set value, the control device 21 is relatively large with respect to the unit amount of water passing through the water supply channel 10. The supply pump 16 is continuously operated so that the pH adjuster of the above is added. On the other hand, when the bicarbonate ion concentration measured in step S5 is close to the preset set value, a relatively small amount of pH adjuster is added to the unit amount of water that passes through the water supply channel 10. The supply pump 16 is continuously operated. That is, the control device 21 operates the supply pump 16 so that the amount of the pH adjusting agent added to the water supply is inversely proportional to the bicarbonate ion concentration measured in step S5. Here, the supply pump 16 continues to operate unless it receives a stop command from the control device 21.

  And after completion | finish of step S12, a program transfers to step S13 and sets a pH adjuster addition identification flag to ON (ON). And after implementing a post-cleaning process in step S15, it returns to step S2.

  As a result, the feed water supplied from the feed water channel 10 into the boiler 2 is introduced with an appropriate amount of pH adjuster according to the bicarbonate ion concentration of the feed water. Effectively suppressed.

  On the other hand, when the bicarbonate ion concentration contained in the water supply sample obtained in the measurement process of step S5 is measured to be a preset value, for example, 10 mg / liter or more, the program proceeds from step S6 to step S7 ( 6), it is determined whether or not the pH adjusting agent addition identification flag of the CPU 48 is ON. If the pH adjuster addition identification flag is off (OFF), the program proceeds to step S10, and after the post-cleaning process is performed as in step S15, the program returns to step S2.

  On the other hand, if the pH adjuster addition identification flag is on (ON) in step S7, the program moves to step S8 and stops the operation of the supply pump 16. Thereby, the medicine supply device 6 stops the supply of the pH adjusting agent to the water supply channel 10. As a result, useless supply of the pH adjuster to the feed water having a hydrogen carbonate ion concentration equal to or higher than a preset value is prevented. After the end of step S8, the program proceeds to step S9 and sets the pH adjuster addition identification flag to OFF (OFF). Then, in step S10, as in step S15, after the post-cleaning process is performed, the process returns to step S2.

Then, the program, in step S2, it is determined whether or not the elapsed time t is reset to zero (0) in step S3 becomes a predetermined time t _1. Then, when the elapsed time t reaches a certain time t ₁ , step S4 and subsequent steps are repeated again. Therefore, in the boiler device 1, the bicarbonate ion concentration in the feed water is measured every time the predetermined time t ₁ elapses, and the pH supplied from the medicine supply device 6 is necessary based on the result. The adjusting agent is added to the water supply through the water supply channel 10.

For example, even if the bicarbonate ion concentration from the water supply in the previous step S5 is less than the preset value, the program is executed if the bicarbonate ion concentration is greater than or equal to the preset value in step S5 in the next repetition process. Shifts from step S6 to step S7. Here, in the previous step S13, the pH adjuster addition identification flag is turned on (ON).
) Is set, the program proceeds to step S8 and returns to step S2 via steps S9 to S10. Therefore, the supply of the pH adjusting agent to the water supply channel 10 is stopped. Conversely, even if the bicarbonate ion concentration from the water supply in the previous step S5 is greater than or equal to the preset set value, the bicarbonate ion concentration from the feed water in the next iteration step is less than the preset set value. In this case, the program proceeds from step S6 to step S11, and returns from step S12 to step S2 via step S15. Therefore, the pH adjusting agent is added from the chemical supply device 6 to the water supplied to the boiler 2 from the water supply channel 10 based on the bicarbonate ion concentration measured in step S5.

  On the other hand, if the bicarbonate ion concentration from the water supply in the previous step S5 is less than the preset value, and the bicarbonate ion concentration is also less than the preset value in step S5 of the next repetition process, the program proceeds to step S6. To step S11, and the supply of the pH adjusting agent to the water supply channel 10 is continued. However, in this case, when the bicarbonate ion concentration measured in the subsequent step S5 is different from the bicarbonate ion concentration measured in the previous step S5, in step S14, the program determines whether the supply pump 16 is based on the bicarbonate ion concentration. Therefore, the amount of the pH adjusting agent added to the feed water supplied from the feed water channel 10 to the boiler 2 changes. That is, in this case, the supply amount of the pH adjusting agent to the water supply channel 10 changes according to the hydrogen carbonate ion concentration contained in the water supply.

  As described above, in the boiler device 1, the pH adjustment agent is not continuously or periodically supplied regardless of the bicarbonate ion concentration in the feed water, but based on the bicarbonate ion concentration. Since the pH adjusting agent can be added to the water supply via the path 10, the amount of the pH adjusting agent used can be optimized, and as a result, the cost required for corrosion inhibition can be reduced. In addition, the boiler device 1 pays attention to hydrogen carbonate ions in the feed water, which is a factor that suppresses the corrosion by thermally decomposing rather than supplying the pH adjuster after the corrosion in the boiler 2 occurs. Since the pH adjusting agent is supplied, corrosion in the boiler 2 can be prevented in advance.

[Other embodiments]
(1) In the embodiment described above, the bicarbonate ion concentration in the water supply is measured every time the predetermined time t ₁ elapses, and based on the result, a pH adjuster is added to the water supply in the water supply channel 10. However, this fixed time t ₁ can be changed according to the situation. For example, as shown in FIG. 7, and further sets the step S16 after step S15 in the operation flowchart, wherein either the elapsed time t is reset to zero (0) at step S3 is reached in a different predetermined time t ₂ Judge whether or not. When it is determined that the elapsed time t in step S16 has reached a predetermined time t _2, the program is configured to go to step S3. Here, the fixed time t ₂ is shorter than the fixed time t ₁ .

In this case, the boiler device 1 measures the bicarbonate ion concentration in the feed water at every elapse of a long fixed time t ₁ when the bicarbonate ion concentration is equal to or higher than the preset value in step S5. If less than the set value bicarbonate ion concentration is preset in S5, it means that measuring the bicarbonate ion concentration in the feed water at every elapse of the short predetermined time t _2, the addition amount of the pH adjusting agent to the water supply Can be optimized.

(2) In the above embodiment, the measuring device 7 measures the bicarbonate ion concentration in the water supply, and based on the result, changes the amount of the pH adjusting agent supplied to the water supply channel 10. However, the present invention is not limited to this. For example, the measuring device 7 simply measures whether or not the bicarbonate ion concentration is less than a preset value in the feed water. If the bicarbonate ion concentration is less than the preset value in the feed water, Regardless of the hydrogen ion concentration, a certain amount of pH adjusting agent may be added to the water supply in the water supply channel 10.

(3) The measuring device 7 used in the above embodiment can be changed to another form as long as it can automatically measure the bicarbonate ion concentration in the water supply. Here, as a method for automatically measuring the bicarbonate ion concentration in the feed water, for example, a measuring device using a TOC meter (organic carbon concentration meter) can also be employed.

(4) In the above embodiment, the boiler device 1 is provided with the measuring device 7, and based on the bicarbonate ion concentration in the feed water automatically measured by the measuring device 7, the medicine supply device 6 Although the pH adjusting agent is supplied to the water supply channel 10, the corrosion inhibiting method of the present invention is not limited to this. For example, the bicarbonate ion concentration in the water supply can be manually measured, and a pH adjuster can be supplied to the water supply channel 10 based on the measurement result. Here, as a method for manually measuring the bicarbonate ion concentration in the water supply, for example, “calculation of the concentration of carbonate, bicarbonate ion and carbonate ion” prescribed in JIS K0101: 1998 may be adopted. it can.

(5) In the above embodiment, the case where the steam used in the load device 4 is not recovered as condensate has been described, but the present invention is not limited to this. For example, as shown in FIG. 9, it is also possible to adopt a configuration in which a condensate pipe 53 (an example of a condensate supply unit) that supplies steam used in the load device 4 to the water supply tank 9 as condensate is provided. It is suitable according to. In this case, makeup water and condensate are mixed in the feed water tank 9 and used as feed water to be supplied to the boiler 2, and the bicarbonate ion concentration of the feed water after mixing the makeup water and the condensate is measured. Therefore, the bicarbonate ion concentration of the feed water supplied to the boiler 2 can be measured, and the amount of pH adjuster used can be optimized.

(6) In each of the above-described embodiments, the case where the bicarbonate ion concentration is measured as the measuring device 7 has been described. However, the addition of a pH adjuster using a device (not shown) that measures the total carbonate concentration is performed. Control is also suitable depending on the implementation.

  Here, the inorganic carbon in the water supply tank 9 is divided into the form of carbonic acid, hydrogen carbonate ions and carbonate ions, and the existence ratio thereof is the structure of the load device 4 and the steam trap (not shown), It differs depending on the length and structure of the condensate pipe 53, the supply method to the water supply tank 9, and the like. Therefore, by measuring as total carbonic acid including these three forms, the total amount of alkali generated in the boiler 2 can be predicted. Therefore, in suppressing corrosion of the boiler 2, the pH adjusting agent The amount used can be optimized. The apparatus for measuring the total carbonic acid concentration is not particularly limited as long as it can measure the presence or absence of total carbonic acid in the feed water or the total carbonic acid concentration. For example, “total carbonic acid” defined in JIS K0101: 1998 can be employed.

1 Boiler device 2 Boiler 3 Water supply device (Water supply section)
4 Load equipment 5 Steam piping (steam supply part)
10 Water supply channel 53 Condensate piping (condensate supply unit)

Claims (2)

  Boiler apparatus comprising a boiler 2 that heats feed water to generate steam, a water supply unit 3 that supplies water to the boiler 2, and a steam supply unit 5 that supplies steam generated by the boiler 2 to a load device 4 1, a method of suppressing corrosion in the boiler 2 using a pH adjuster, and measuring the total carbonic acid concentration of the feed water in the water supply channel 10 of the water supply unit 3 at regular intervals, and this measurement Based on the measurement result in the process, the supply amount determination step for determining the supply amount of the pH adjuster each time, and the pH adjustment for the water supply unit 3 based on the supply amount determined in the supply amount determination step PH adjustment agent supply step for supplying the agent, the measurement interval in the measurement step can be adjusted according to the measurement value of the total carbonic acid, and in the supply amount determination step, from the feed water containing the total carbonic acid heat The supply amount of the pH adjusting agent can be adjusted so as to eliminate the waste of the supply amount of the pH adjusting agent by calculating the optimum supply amount for suppressing the corrosion of the boiler 2 in consideration of the alkali generated by the solution A method for inhibiting corrosion of a boiler device, characterized in that   A boiler 2 that heats feed water to generate steam, a water supply unit 3 that supplies water to the boiler 2, a steam supply unit 5 that supplies steam generated by the boiler 2 to a load device 4, and the load device 4 In the boiler apparatus 1 provided with the condensate supply unit 53 that supplies the steam used in the process to the water supply unit 3 as condensate, a method of suppressing corrosion in the boiler 2 using a pH adjuster, for a certain period of time A measurement step for measuring the total carbonic acid concentration of the feed water in the water supply channel 10 of the water supply unit 3 and a supply amount determination step for determining the supply amount of the pH adjuster each time based on the measurement result in this measurement step And a pH adjusting agent supplying step for supplying a pH adjusting agent to the water supply unit 3 based on the supplying amount determined in the supplying amount determining step, and the measurement interval in the measuring step is the total carbonic acid. According to measured value In addition, in the supply amount determination step, an optimal supply amount for suppressing corrosion of the boiler 2 is calculated in consideration of alkali generated by thermal decomposition from feed water containing total carbonic acid, A method for inhibiting corrosion of a boiler device, characterized in that the supply amount of the pH adjusting agent can be adjusted so as to eliminate waste of the supply amount of the pH adjusting agent.

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