JP5789987B2 - Rust prevention method - Google Patents

Description

The present invention relates to a rust prevention method for suppressing rusting of metal equipment constituting a water system.

  For example, in power plants, rusting interferes with power generation, such as the cooling water system of important equipment required for power generation, and it affects power generation such as extremely problematic systems, fire fighting water systems, and miscellaneous water systems. A water system that does not affect the water is provided. In important facilities where rusting is a problem, rust prevention treatment of metal facilities in water systems, internal treatment treatment such as painting and lining on the inner surface of metal facilities, and introduction of rust preventives (chemicals) into the water Has been done. However, water pipes that do not affect power generation are not subjected to rust prevention treatment from a cost standpoint, or are water pipes that are always drained and discharged and cannot be subjected to rust prevention treatment from an environmental point of view. Many.

  Here, deodorizers using microorganisms classified as Bacillus subtilis do not treat bad odors superficially, but fundamentally decompose and deodorize them, even if filth adheres to them There is one that can deodorize not only direct deodorization but also malodor present in the surrounding space (for example, see Patent Document 1). In addition, there is one in which microorganisms classified as Bacillus subtilis are contained in circulating water as active ingredients to efficiently and safely remove dirt, germs and other organic substances in water (for example, see Patent Document 2). Furthermore, there exists a mineral containing water-soluble rust preventive solution which added the ionized mineral to the fermentation liquid of the useful microorganism group as a rust preventive using a useful microorganism group (for example, refer patent document 3). Ionized minerals are added to the fermentation broth of useful microorganisms in an amount of about 2 wt%.

JP-A-9-275975 JP 2001-104991 A JP 2002-20885 A

  However, when the rust prevention treatment is performed for the rust prevention of the metal equipment, not only the cost is increased, but even if the rust prevention treatment is performed, the rust prevention effect is lowered with the passage of time, so that it is not perfect. In addition, when a rust preventive agent is regularly added to tanks and pipes that are metal equipment of the water system, the water with the rust preventive agent cannot be drained to the outside as it is for environmental conservation. Processing is required. Furthermore, even in irrigation systems where rusting is not considered as a problem, the irrigation on the inner surface of metal facilities due to aging causes the water to turn red, and the landscape of the sprinkling area is significantly impaired after the use of the irrigation water.

  On the other hand, Bacillus subtilis is a safe microorganism and there is no environmental problem even if it is discharged to the outside as it is. However, in Patent Document 1, Bacillus subtilis is used for deodorization and not for rust prevention. Also in Patent Document 2, Bacillus subtilis is used for efficiently and safely removing dirt in the water, germs and other organic substances, not for rust prevention. Furthermore, the anticorrosive solution described in Patent Document 3 requires fermentation treatment of useful microorganisms and addition of minerals, which increases costs.

An object of the present invention is to provide a rust-preventing method capable of rust- proofing a metal inexpensively, environmentally friendly and easily.

In the rust prevention method according to the first aspect of the present invention, a rust preventive agent mainly composed of Bacillus subtilis that decomposes fats and oils, which are organic substances, is introduced into the irrigation system water in the power plant, and the irrigation system in the irrigation system comes into contact. In rust-proofing the metal equipment of the irrigation system, the rust-preventing agent is added to the irrigation water in the irrigation system that has not been subjected to any chemical treatment for rusting in the irrigation system. Water spraying is performed from the water spray nozzle to the LNG tank using irrigation water to rust the metal equipment of the in-house water system .

  Hereinafter, the background to the present invention will be described. Bacillus subtilis is a microorganism that decomposes fats and oils, which are organic substances, and is used for peeling and decomposing slime and deposited sludge adhering to the inner surface of pipes and tanks of water systems. In other words, Bacillus subtilis spores react with oxygen using organic matter as nutrients to become vegetative cells of Bacillus subtilis, which work on the oils and substances that cause malodors to decompose fats and oils and remove malodors. Although it is known that it is effective against decomposition of the metal, its effectiveness has not yet been confirmed with respect to the suppression of rusting on inorganic metals.

  Therefore, the inventors have conceived that Bacillus subtilis is also effective in suppressing rusting on metals, and conducted the following experiments. As a result of intensive studies, they have found that Bacillus subtilis has an antirust effect.

  FIG. 1 is a photograph of an experimental process of the rust prevention effect by Bacillus subtilis of the present invention. As shown in FIG. 1 (a), in order to confirm the influence of Bacillus subtilis on rusting, a container 11a in which Bacillus subtilis is introduced into tap water and a container 11b in which tap water is simply added are prepared, and the same degree is provided for each. The keys 12a and 12b, which are metal member samples in a slightly rusted state, were immersed. In addition, the keys 12a and 12b of the metal member sample are plated with antirust treatment. Hereinafter, sample A is a sample in which a key 12a is immersed in a container 11a in which Bacillus subtilis is introduced into tap water, and sample B is a sample in which the key 12b is simply immersed in a container 11b in which tap water is added.

  FIG. 1B shows a state in which three days have passed since the state of FIG. Sample A showed little change in the color of the water. On the other hand, in sample B, the water was slightly rusted.

  FIG. 1C shows a state in which 7 days have passed since the state in FIG. 1A (a state in which 4 days have passed since the state in FIG. 1B). Sample A showed little change in the color of the water. On the other hand, in Sample B, the water had a darker rust color than in the case of FIG.

  FIG. 1D shows a state where 15 days have passed since the state of FIG. 1A (a state where 8 days have passed since the state of FIG. 1C). Sample A showed little change in the color of the water. On the other hand, in Sample B, the water had a darker rust color than in the case of FIG. Moreover, what immersed the rusty number wire | line 13 in the container 11c which put the tap water 5 days ago as the middle sample C at this time was added. The number wire 13 is a metal member that has not been subjected to rust prevention treatment.

  FIG. 1E shows a state where 18 days have passed since the state of FIG. 1A (a state where 3 days have passed since the state of FIG. 1D). Sample A showed little change in the color of the water. On the other hand, in Sample B, the water had a darker rust color than in the case of FIG. In Sample C, a deeper rust color was obtained. Bacillus subtilis was added to Sample B in this state.

  FIG. 1 (f) shows a state in which 23 days have elapsed from the state of FIG. 1 (a) (a state in which 5 days have elapsed from the state of FIG. 1 (e)). Sample A showed little change in the color of the water. On the other hand, in Sample B, since Bacillus subtilis was introduced, the water became clearer than in the case of FIG. Further, in sample C, the rust color became darker and became cloudy so that the wire 13 was hardly visible.

  As can be seen from the above experimental results, in the sample A of tap water charged with Bacillus subtilis, no progress of rust was observed, and the water was almost transparent with no change. On the other hand, the sample B of tap water progressed to rust, and the water also changed to rust color, so-called red water. When Bacillus subtilis was introduced in this process, red water became clear. Further, the number 13 of the sample C added during the process was not subjected to rust-proof plating like the keys 12a and 12b, so the red water progressed quickly.

  FIG. 2 is a photograph of the metal members taken out by evaporating the moisture of the samples A, B, and C of FIG. In sample A, the state of the key 12a at the start of the experiment was almost the same, and in sample B, rust progressed to the key 12b and rust was also produced. Further, in sample C, rust further progressed on the wire 13, and the amount of rust was larger than that of sample B. From these experimental results, it was confirmed that Bacillus subtilis is effective in preventing rusting, preventing red water from being used, and clarifying red water.

  According to the present invention, Bacillus subtilis can be used as a metal rust preventive agent because it is effective for preventing rusting, preventing red water from becoming red water, and transparentizing red water. Therefore, by introducing Bacillus subtilis into the irrigation system that handles water, it is possible to prevent red water with rust prevention and rust prevention on the inner surface of the irrigation system. Further, as a general purpose application, it is possible to prevent rust by spraying a Bacillus subtilis solution on the metal surface. At this time, the fermentation treatment of bacteria and the addition of minerals are unnecessary and can be rusted at low cost. Furthermore, the use of Bacillus subtilis as a rust preventive agent eliminates the need for water treatment during drainage.

The photograph figure of the experimental process of the rust prevention effect by Bacillus subtilis of this invention. The photograph figure which took out the metal member by evaporating the water | moisture content of each sample A, B, and C of FIG.1 (f). A photograph of the area around the filtered water tank with water spray and water curtain right after the introduction of Bacillus subtilis. A photograph of the area around the filtered water tank with watering and water curtains 6 months after the introduction of Bacillus subtilis. The graph of the monthly water quality analysis result of the vaporizer seawater cooling water tank shown in Table 1. The photograph figure which shows the change of iron content after putting in Bacillus subtilis.

  Embodiments of the present invention will be described below. Since we have found that Bacillus subtilis has a rust-preventing effect, we considered its use in an in-house water system in power plants that have not been treated with any chemicals for rust prevention. We examined the use of this system in the irrigation system where the dissolved oxygen is controlled by chemicals.

  As Bacillus subtilis, those isolated from the natural environment and microorganisms classified as commercially available Bacillus subtilis can be used.

  First, the use of Bacillus subtilis in an in-house water system in a power plant that has not been subjected to any chemical treatment for rust prevention will be described.

  The in-house irrigation system is filled with freshwater firefighting system and seawater firefighting system, has not been treated with any chemicals, and conventionally supplies system water from a filtered water tank. The system water is always red water due to rust, and the corrosion of pipes is intense due to rust, and leaks due to pinholes, cracks, etc. occur frequently. Furthermore, in each sprinkling and water film operation confirmation test, clogging of rust debris such as sprinkling water nozzles and blow lines frequently occurs, which increases the amount of work and cost. Also, since the drainage in the water curtain and sprinkling test is red water, the roof, side walls, racks, ground surface, gutters, etc. of the LNG tank are stained red after the water curtain and sprinkling test, and it has not been solved as a conventional problem .

  Therefore, Bacillus subtilis was introduced directly into the adjacent filtrate tank of the fire extinguishing system, which is an in-house water system. FIG. 3 is a photographic view of the area around the LNG tank in a state where watering and water curtains have been performed immediately after the introduction of Bacillus subtilis, FIG. 3 (a) is a photographic view of a side groove, and FIG. 3 (b) is a view of the LNG tank 14. FIG. 3 (c) is a photograph of the water spray / water curtain, FIG. 3 (d) is a photograph of the upper part of the LNG tank 14, and FIG. 3 (e) is a photograph of an adjacent rainwater drainage tank. In this state, it can be presumed that the filtered water in which Bacillus subtilis is introduced into the pipe is almost full, but as can be seen from FIGS. 3 (a) to 3 (e), the drainage is clouded by red water.

  FIG. 4 is a photographic view of the area around the LNG tank in a state where watering and water curtains were performed 6 months after the introduction of Bacillus subtilis, and FIG. 4 (a) is a photographic view of a side groove, FIG. 4 (b). Fig. 4 (c) is a photograph of the water spray / water curtain, Fig. 4 (d) is a photograph of the upper part of the LNG tank 14, and Fig. 4 (e). Is a photograph of an adjacent rainwater drainage tank. As can be seen from FIG. 4 (a) to FIG. 4 (d), the water is beautiful, and as can be seen from FIG. 4 (e), the reddish color fades and changes to soil color and turbidity decreases. Yes.

  In this way, since the turbidity of the drainage is reduced, it is possible to suppress rusting of various facilities as well as measures against red water in the sprinkling water curtain piping. Bacillus subtilis is environmentally friendly, so even if it is drained as it is, it can be considered that it cleans the gutters and adjacent rainwater drainage tanks and cleans the river and soil.

  Next, the use of Bacillus subtilis for irrigation system facilities that manage dissolved oxygen by introducing chemicals for rust prevention by deoxygenation will be described.

  At present, the cooling water for the vaporizer seawater pump motor is being circulated through the cooling water system from the vaporizer seawater cooling water tank, and the phosphoric acid chemical “Krillex L-110” is appropriately added to prevent rust. Countermeasures and equipment maintenance are performed. For water quality management of cooling water, monthly water quality analysis is performed, and phosphoric acid concentration, turbidity, iron concentration, etc. are confirmed. When each standard value is exceeded, chemicals are charged or in-house water is replaced in the cooling water storage tank. Implement and manage water quality.

Therefore, Bacillus subtilis was introduced into the vaporizer seawater cooling water tank as an alternative to the rust preventive agent (chemical: Krillex L-110) for the vaporizer seawater cooling water tank. Regarding the charging of Bacillus subtilis, the additional charging of the chemical (Krillex L-110) that had already been added was stopped, and Bacillus subtilis was added after the chemical in the cooling water (Chrilex L-110) was reduced to some extent. Further, the amount of Bacillus subtilis was 10 ppm as the concentration of Bacillus subtilis in the cooling water tank. Therefore, since the tank capacity per cooling water tank was 30 m ³ , 300 ml was added.

Monthly water quality analysis results of the vaporizer seawater cooling water tank when the chemical (Crillex L-110) is stopped from being added and then Bacillus subtilis is added. Table 1 shows.

  FIG. 5 is a graph of monthly water quality analysis results of the vaporizer seawater cooling water tank shown in Table 1. Curve S1 is the electrical conductivity, curve S2 is the concentration of the chemical (Krillex L-110), curve S3 is the turbidity, curve S4 is the pH, and curve S5 is the iron concentration.

  At the time t1 of the fourth month after the start of the monthly water quality measurement of the vaporizer seawater cooling water tank, the addition of the rust preventive chemical (Crillex L-110) was stopped, and the chemical “Crillex L” -110 "rust prevention effect is no longer about 2 months, so the hay at the time t2 of the 6th month after the start of the measurement almost 2 months from the time t1 of the 4th month when the introduction of the chemical" Kurilex L-110 "is stopped The fungus was introduced. Therefore, the effect of Bacillus subtilis is determined by data after time t2.

  As can be seen from Table 1 and FIG. 5, the iron content was always 1 mg / l or more before Bacillus subtilis was introduced (before time t2), but after 2 months have elapsed since the introduction of Bacillus subtilis (time t3), Iron content dropped to 0.5 mg / l.

  In accordance with this, the turbidity decreased to 6.4 degrees. Turbidity is a measure of the permeability in water and itself represents a decrease in iron content. The change in iron content is measured by the shading of the color through which the sample water is passed by the Millbois filter used for analysis. FIG. 6 is a photographic diagram showing changes in iron content, FIG. 6 (a) is a photographic diagram for the seventh month, and FIG. 6 (b) is a photographic diagram for the eighth month (time point t3). As can be seen from FIG. 6, it clearly changes to a light color, and it can be seen at a glance that the iron content is reduced. Thus, a remarkable effect appeared in the analysis two months after the introduction of Bacillus subtilis. Even after 5 months, the iron content is maintained at about 0.5 mg / l, and the turbidity is lowered to 3.3 degrees.

  As described above, it was confirmed that there was no problem in use in water system facilities in which chemical concentration control was performed by adding chemicals for rust prevention by forming a protective film. Since Bacillus subtilis can be used as an alternative to rust preventive chemicals, it is possible to reduce the environmental burden by reducing the use of chemicals, and there is also an effect that there is no need to worry about drainage by blow during equipment inspection of the water system.

  In order to investigate the mechanism of rust prevention by Bacillus subtilis, the concentration of dissolved oxygen in water with and without Bacillus subtilis was compared.

  Tap water and tap water charged with Bacillus subtilis were prepared, each was put in a separate plastic bottle, and the lid was closed and left. Six days and 20 days after the start of standing, a small amount of liquid was transferred from each PET bottle to a beaker, and the dissolved oxygen concentration was measured.

The dissolved oxygen concentration was measured using a low concentration portable dissolved oxygen meter (D0-32A manufactured by Toa DKK Corporation). A dissolved oxygen electrode was placed in a beaker without a lid, and the measurement was performed under open conditions. Table 2 shows the measurement results.

  From Table 2, the concentration of dissolved oxygen in tap water with Bacillus subtilis decreased rapidly, and was about 1/3 after 6 days and about 1/16 after 20 days compared to tap water. Considering the decrease in dissolved oxygen concentration, it is assumed that the corrosion rate of iron is at least about 1/16 (about 0.006 mm / yr) in the environment of tap water charged with Bacillus subtilis than normal tap water. Therefore, it is conceivable that the dissolved oxygen concentration in the water was lowered as one of the factors that exerted the rust prevention effect by introducing Bacillus subtilis.

DESCRIPTION OF SYMBOLS 11 ... Container, 12 ... Key, 13 ... Number line, 14 ... LNG tank, 15 ... Water supply mother pipe, 16 ... Sprinkling water curtain nozzle

Claims (1)

Injecting a rust preventive agent mainly composed of Bacillus subtilis that decomposes fats and oils that are organic matter into the water of the irrigation system in the power plant, and rusting the metal equipment of the irrigation system that the irrigation system of the irrigation system contacts,
Injecting the rust inhibitor into the irrigation water of the in-house irrigation system that is not subjected to any chemical treatment for rust prevention among the irrigation system,
A rust-preventing method, comprising spraying a water spray screen from a water spray nozzle to an LNG tank using the water of the in-house water system to rust the metal equipment of the in-house water system.