JP2011033301A - Corrosion suppressing method and corrosion suppressing device for boiler device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosion suppressing method and a corrosion suppressing device which effectively, easily and conveniently suppresses corrosion in a retrieving part of a boiler device using counteractive amine and coating forming amine together. <P>SOLUTION: The corrosion suppressing device 20 includes an addition part 30 for adding the counteractive amine and long chain aliphatic amine with the carbon number of 10 to 24 to the boiler device 60 at a constant ratio, a detection part 40 for detecting pH and/or electrical conductivity of condensed water of steam generated by a boiler 63, and a control unit 50 for controlling the addition part 30 so as to adjust the added amounts of the counteractive amine and the long chain aliphatic amine based on the detection result by the detection part 40. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a corrosion control method and a corrosion suppression device for a boiler device.

  Conventionally, a boiler device collects condensate generated from steam generated in a boiler and reuses it as feed water. In such a boiler device, sodium bicarbonate contained in the feed water is mainly pyrolyzed in the boiler to generate carbon dioxide gas, which is transferred to the steam system together with steam, dissolved in the condensate, and the pH of the condensate. Reduce. As a result, corrosion occurs in the portion that comes into contact with the condensate (condensate recovery unit), and as a result, the equipment is thinned.

  Therefore, in order to suppress corrosion in the recovery unit of the boiler device, a measure is taken to increase the pH of the condensate by adding a neutralizing amine to the feed water or steam. However, in order to effectively suppress corrosion in this measure, it is necessary to appropriately adjust the amount of neutralizing amine added. Conventionally, the adjustment of the addition amount of neutralizing amine is based on the determination result of the pH of the condensate (see Patent Documents 1 and 2), based on the measured value of the carbonate concentration of the condensate (see Patent Document 3), This is performed based on the residual concentration of neutralizing amine in the condensate (see Patent Document 4).

JP 2003-343804 A JP 2008-156698 A JP 2005-337585 A JP 2008-170113 A

  By the way, as a corrosion inhibitor added to a boiler apparatus, a film-forming amine such as octadecylamine is attracting attention in addition to a neutralizing amine. The film-forming amine has a function of preventing corrosion by forming a corrosion-proof film on the boiler device, thereby avoiding direct contact between the condensate and the recovery unit. Thus, since the film-forming amine complements the neutralizing amine, it is expected that the corrosion in the boiler apparatus can be significantly suppressed when used in combination with the neutralizing amine.

  However, when a film-forming amine is used, it is difficult to measure the concentration of the film-forming amine in the condensate at the site of the boiler apparatus. For this reason, in order to adjust the amount of film-forming amine added, a portion of the condensate is collected and the concentration of the film-forming amine is measured using ion chromatography in an experimental facility, or a test piece immersed in the condensate is removed. Samples must be taken at appropriate intervals to calculate the corrosion rate, and the work is complicated.

  The present invention has been made in view of the above circumstances, and uses a neutralizing amine and a film-forming amine in combination, and a corrosion inhibiting method and a corrosion inhibiting apparatus capable of effectively and simply inhibiting corrosion in a recovery part of a boiler device. The purpose is to provide.

  The inventor added neutralizing amine and film-forming amine in a certain ratio, so that the pH and electrical conductivity of the condensed water of steam generated in the boiler reflected the film-forming amine concentration in the condensate. As a result, the present invention has been completed. Specifically, the present invention provides the following.

(1) A boiler that heats feed water to generate steam, a water supply unit that supplies water to the boiler, and a recovery unit that condenses the steam generated in the boiler and returns the generated condensate to the water supply unit A corrosion inhibiting method for inhibiting corrosion in the recovery part of the boiler device comprising:
Adding a neutral amine and a long-chain aliphatic amine having 10 to 24 carbon atoms to the boiler device at a constant ratio;
Corrosion having a step of detecting the pH and / or electric conductivity of steam condensate generated in the boiler and adjusting the addition amount of the neutralizing amine and the long-chain aliphatic amine based on the detection result Suppression method.

  (2) The method for inhibiting corrosion according to (1), wherein the neutralizing amine and the long-chain aliphatic amine use a one-component corrosion inhibitor mixed with these.

(3) A boiler that heats feed water to generate steam, a water supply unit that supplies water to the boiler, and a recovery unit that condenses the steam generated by the boiler and returns the generated condensate to the water supply unit A corrosion suppressing device for suppressing corrosion in the recovery unit of the boiler device comprising:
An adding means for adding a neutral amine and a long-chain aliphatic amine having 10 to 24 carbon atoms to the boiler device at a constant ratio;
Detection means for detecting the pH and / or electrical conductivity of the condensed water of the steam generated in the boiler;
A corrosion inhibiting device comprising: control means for controlling the addition means so as to adjust the addition amount of the neutralizing amine and the long-chain aliphatic amine based on the detection result by the detection means.

  According to the present invention, the neutralizing amine and the long chain aliphatic amine having 10 to 24 carbon atoms (film-forming amine) are added at a constant ratio, so that the pH and electrical conductivity of the condensed water of the steam generated in the boiler The rate reflects the concentration of long chain aliphatic amine having 10 to 24 carbon atoms in the condensate. For this reason, it is possible to detect the pH and / or electrical conductivity of steam condensate produced in the boiler, and adjust the total amount of amine added based on the detection result, so that the number of carbon atoms in the condensate is 10 to 24. The long chain aliphatic amine concentration is adjusted to the desired range. Therefore, the neutralization amine and the film-forming amine are used in combination, and corrosion in the recovery unit of the boiler device can be effectively and simply suppressed.

It is a block diagram of the corrosion control device concerning one embodiment of the present invention. It is a graph which shows transition of pH of the condensed water of steam at the time of implementing the corrosion control method concerning one embodiment of the present invention. It is a graph which shows the relationship between the pH of the condensed water of a vapor | steam, and the long-chain aliphatic amine density | concentration in condensed water.

  Hereinafter, although embodiment of this invention is described, this invention is not specifically limited to this.

  FIG. 1 is a block diagram of a corrosion inhibiting device 20 according to an embodiment of the present invention. As shown in FIG. 1, the boiler system 10 includes a boiler device 60 and a corrosion suppression device 20. Details of each element will be described below.

[Boiler equipment]
The boiler device 60 includes a water supply unit 61 that supplies water to a boiler 63 described later. Specifically, the water supply unit 61 includes a water softener 611, which removes hardness components such as calcium components and magnesium components from raw water to prepare soft water. After this soft water is introduced into the water supply tank 613 and stored as necessary, a desired amount of soft water is supplied to the boiler 63 through the water supply path 615 by the driving force of the water supply pump 617.

  The boiler 63 of the boiler device 60 heats the feed water supplied from the water supply unit 61 to generate steam. The steam is condensed in the recovery unit 65 of the boiler device 60, and the generated condensate is returned to the water supply unit 61. It is. Specifically, the steam from the boiler 63 is recovered in the header 653 through the steam recovery path 651 and distributed to the steam introduction path 655 and the sampling path 42 extending from the header 653 at a desired ratio. The steam distributed to the steam introduction path 655 is introduced into the steam load section 657 and condensed by the steam load section 657, thereby generating condensate. This condensate is recovered in the water supply tank 613 through the condensate recovery path 659 and reused as water supply for the boiler 63.

  In such a boiler device 60, sodium bicarbonate contained in the feed water is mainly thermally decomposed in the boiler 63 to generate carbon dioxide gas. This carbon dioxide gas is transferred to the recovery unit 65 together with the steam, dissolved in the condensate, and recovered. Reduce the pH of the water. For this reason, in particular, corrosion is likely to occur in the recovery portions 65 such as the steam load portion 657 and the condensate recovery path 659 that come into contact with the condensate. An apparatus for suppressing such corrosion will be described below.

[Corrosion suppression device]
The corrosion suppression apparatus 20 includes an addition unit 30 as an addition unit, a detection unit 40 as a detection unit, and a control unit 50 as a control unit. The addition unit 30 includes an inhibitor tank 31 that stores the corrosion inhibitor, and the corrosion inhibitor in the inhibitor tank 31 is supplied to the water supply passage 615 through the inhibitor supply passage 33. The corrosion inhibitor supplied to the water supply channel 615 becomes steam heated in the boiler 63 together with the water supply and moves to the recovery unit 65 to suppress corrosion. The amount and timing of supplying the corrosion inhibitor can be changed by driving the inhibitor supply pump 35. In addition, although the addition place of the corrosion inhibitor was the water supply path 615 in this embodiment, it is not restricted to this, The vicinity of the appropriate place of the water supply part 61 and / or the boiler 63 and / or the header 653, etc. may be sufficient.

  In the present invention, as the corrosion inhibitor, a neutralizing amine and a long chain aliphatic amine having 10 to 24 carbon atoms are used in combination. In addition, as a corrosion inhibitor, you may use conventionally well-known arbitrary components together with a neutralizing amine and a long-chain aliphatic amine as needed.

  The neutralizing amine is not particularly limited as long as it is a volatile amine compound. For example, cyclohexylamine, morpholine, monoethanolamine, monoisopropanolamine, diethylethanolamine, 2-amino-2-methyl-1-propanol, And one or more selected from the group consisting of ammonia and the like. Such neutralizing amine suppresses corrosion by raising the pH of condensate.

  Long-chain aliphatic amines prevent corrosion by forming an anticorrosion film in the recovery part 65 such as the steam load part 657 and the condensate recovery path 659 where corrosion is a particular problem. If the number of carbon atoms of the long-chain aliphatic group is too small, the ability to form an anticorrosion film tends to be insufficient, and if it is too large, the emulsion will gel and the stability tends to be insufficient. Therefore, the carbon number of the long-chain aliphatic group is 10 or more and 24 or less, preferably 10 or more and 22 or less, more preferably 12 or more and 20 or less.

  The long chain aliphatic group constituting the long chain aliphatic amine compound may or may not contain an unsaturated bond. In the amino group constituting the long-chain aliphatic amine compound, the hydrogen portion may be substituted with a hydrocarbon group such as a methyl group or an ethyl group. The long chain aliphatic amine compound may be a fatty acid salt. In this case, examples of the fatty acid constituting the fatty acid salt include oleic acid, lauric acid, and stearic acid.

  Specific examples of the long-chain aliphatic amine are not particularly limited, but are saturated such as dodecylamine, tridecylamine, tetradecylamine, heptadecylamine, hexadecylamine, octadecylamine, nonadecylamine, eicosylamine, docosylamine and the like. One or more kinds of mixed amines such as unsaturated aliphatic amines such as aliphatic amines, oleyl amines, ricinoleyl amines, linoleyl amines, linoleyl amines, coconut oil amines, and hardened tallow amines may be mentioned. Above all, it is approved as an additive for boiler water in the US FDA standard, and there is no problem in terms of safety even if steam generated from the boiler leaks, so octadecylamine is used in the food manufacturing industry. preferable.

  In addition to the corrosion inhibitor, in order to suppress the scale in the boiler 63, a cleansing agent may be added. In the present embodiment, the cleaning agent stored in the cleaning agent tank 36 of the addition unit 30 is introduced into the water supply channel 615 through the cleaning agent supply channel 37 by the driving force of the cleaning agent supply pump 38. . In addition, the location and timing of the addition of the canning agent may be independent of the corrosion inhibitor, and the components of the canning agent may be appropriately selected.

  Thus, since the long-chain aliphatic amine complements the neutralizing amine, it is expected that the corrosion in the boiler device 60 can be significantly suppressed when used in combination with the neutralizing amine. However, in order to effectively suppress corrosion, it is particularly necessary to simply optimize the amount of long-chain aliphatic amine added. Surprisingly, however, the inventor added the neutralizing amine and the long-chain aliphatic amine at a constant ratio, as shown in the examples described later, so that the pH of the condensed water of the steam generated in the boiler was increased. And the electrical conductivity was found to reflect the long chain aliphatic amine concentration in the condensate.

  Therefore, in the present invention, the neutralizing amine and the long-chain aliphatic amine are added at a constant ratio. Here, the “constant ratio” is not limited to that the ratio is always constant, but also includes that the ratio average value of a period set as appropriate is constant. Moreover, the timing and place where the neutralizing amine and the long-chain aliphatic amine are added may be the same or different. However, it is preferable to use a one-part corrosion inhibitor in which a neutralizing amine and a long-chain aliphatic amine are mixed, as in this embodiment, in that the addition equipment can be simplified and the ratio can be accurately set. .

  Moreover, the detection part 40 detects the pH and / or electrical conductivity of the condensed water of the vapor | steam produced | generated with a boiler. Specifically, a sampling valve 421 is provided in the sampling path 42 extending from the header 653 described above, and a part of the steam is distributed to the sampling path 42 according to the opening and closing of the sampling valve 421. The steam distributed to the collection channel 42 is introduced into the heat exchanger 41, and is cooled by the heat exchanger 41 to become condensed water. The condensed water is introduced into the pH meter 45 through the condensed water introduction passage 43 according to the opening and closing of the introduction valve 431, and is discharged after the pH is detected by the pH meter 45.

  Information (detection result) on the pH detected by the pH meter 45 is transmitted to the control unit 50. The control unit 50 controls the inhibitor supply pump 35 so as to adjust the addition amount of the neutralizing amine and the long-chain aliphatic amine based on the detection result. Specifically, the control unit 50 increases the addition amount when the pH is smaller than the desired range, and decreases the addition amount when the pH is larger than the desired range. Thereby, as a result of the pH falling within the desired range, the long-chain aliphatic amine concentration in the condensate can also be adjusted to the desired range. Moreover, corrosion can be suppressed synergistically by setting a desired range to the range (for example, 6 or more) from which corrosion does not occur easily. The pH meter 45 may be a conventionally known device.

  In the present embodiment, the pH value of the condensed water is measured in order to improve control accuracy. However, the present invention is not limited to this, and it may be detected whether the pH belongs to a predetermined range. For example, it is possible to detect whether or not the pH of the condensed water belongs to a predetermined range by adding an indicator that colors according to pH to the condensed water and monitoring the color after the addition mechanically or visually.

  Moreover, you may adjust the addition amount of a neutralizing amine and a long-chain aliphatic amine based on the detection result of an electrical conductivity instead of the pH of condensed water or with pH. The electrical conductivity may be detected by a conventional method using a conventionally known measuring instrument.

  Note that the condensed water targeted for detection in the present embodiment is obtained by condensing the steam distributed from the header 653. However, the present invention is not limited to this, and a header is provided immediately before the steam load unit 657 and distributed from this header. The vapor may be condensed or a part of the condensate flowing through the condensate recovery path 659 may be used.

  Using the boiler system 10 shown in FIG. 1, softened water of Atsugi city water saturated with oxygen in the air at 40 ° C. is supplied to a 5 liter experimental electric boiler 63, temperature 183 ° C., pressure 1 MPa, steam The steam was generated for 3 days by operating at a generation rate of 12 liters / hour and a blow rate of 10%. Further, a corrosion inhibitor containing aminomethylpropanol as a neutralizing amine and octadecylamine as a long-chain aliphatic amine at a constant ratio (aminomethylpropanol: octadecylamine = 37: 1.5 (mass ratio)). Was added from the inhibitor supply path 33 to the water supply path 615.

  The steam generated from the boiler 63 was continuously distributed to the collection channel 42 little by little, and the pH of the condensed water was measured with a pH meter 45. In the examples, the pH of the condensed water was kept constant at about 6 by adjusting the addition amount of the corrosion inhibitor according to the increase or decrease of the measured value. Moreover, in the comparative example, the addition amount of the corrosion inhibitor was not adjusted and kept fixed at a constant value. The transition of the pH of the condensed water in Examples and Comparative Examples is shown in FIG.

  In Examples and Comparative Examples, a part of the condensate flowing through the condensate recovery path 659 was continuously recovered, and the octadecylamine concentration was analyzed by ion chromatography. The relationship between the octadecylamine (ODA) concentration and the pH of the condensed water is shown in FIG. In addition, the pH of the condensed water and the octadecylamine concentration at each time point shown in FIG.

  In the comparative example, the pH of the condensed water varied greatly from 4.9 to 6.7 (FIG. 2), and the octadecylamine concentration in the condensate also varied significantly (FIG. 3). In contrast, in the examples, the pH of the condensed water was stable at about 6 (FIG. 2), and the fluctuation range of the octadecylamine concentration in the condensate was much narrower than that of the comparative example (FIG. 3).

  Thereby, when neutralizing amine and long-chain aliphatic amine are added at a constant ratio, the long-chain aliphatic amine concentration in the condensate can be suitably controlled based on the pH of the condensed water of steam generated in the boiler. I understood.

  It is known that the neutralizing amine concentration in water correlates with the electrical conductivity of the water. Based on this fact and the above conclusion, when a neutralizing amine and a long-chain aliphatic amine are added at a certain ratio, the neutralizing amine concentration in the condensate and the long-chain having a certain relationship with the neutralizing amine concentration are determined. It is presumed that the aliphatic amine concentration can also be suitably controlled based on the electric conductivity of the condensed water of the steam generated in the boiler.

  Therefore, by detecting the pH and / or electrical conductivity of steam condensate produced in the boiler, and adjusting the total amount of amine added based on the detection result, the length of carbon in the condensate is 10-24. Since the chain aliphatic amine concentration was adjusted to the desired range, it was found that the neutralization amine and the film-forming amine can be used in combination to effectively and easily suppress corrosion in the recovery unit of the boiler device.

20 Corrosion inhibitor 30 Addition part (addition means)
40 Detection unit (detection means)
50 Control unit (control means)
60 Boiler device 61 Water supply unit 63 Boiler 65 Recovery unit

Claims (3)

A boiler that generates steam by heating feed water, a water supply unit that supplies the boiler with water, and a recovery unit that condenses the steam generated in the boiler and returns the generated condensate to the water supply unit. A corrosion suppressing method for suppressing corrosion in the recovery unit of the boiler device comprising:
Adding a neutral amine and a long-chain aliphatic amine having 10 to 24 carbon atoms to the boiler device at a constant ratio;
Corrosion having a step of detecting the pH and / or electric conductivity of steam condensate generated in the boiler and adjusting the addition amount of the neutralizing amine and the long-chain aliphatic amine based on the detection result Suppression method.   The corrosion inhibition method according to claim 1, wherein the neutralizing amine and the long-chain aliphatic amine are a one-component corrosion inhibitor mixed with these. A boiler that generates steam by heating feed water, a water supply unit that supplies the boiler with water, and a recovery unit that condenses the steam generated in the boiler and returns the generated condensate to the water supply unit. A corrosion suppression device that suppresses corrosion in the recovery unit of the boiler device comprising:
An adding means for adding a neutral amine and a long-chain aliphatic amine having 10 to 24 carbon atoms to the boiler device at a constant ratio;
Detection means for detecting the pH and / or electrical conductivity of the condensed water of the steam generated in the boiler;
A corrosion inhibiting device comprising: control means for controlling the addition means so as to adjust the addition amount of the neutralizing amine and the long-chain aliphatic amine based on the detection result by the detection means.