JP2014070267A - Anticorrosion method of steam generation facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anticorrosion method of a steam generation facility in which a non-volatile anticorrosion agent is made to reach a terminal of a steam circuit, and excellent anticorrosion effect can be exhibited to both a steel material and a copper material.SOLUTION: An anticorrosion method of a steam generation facility is that an anticorrosion agent including fats is added by being blown out from a spray nozzle into a steam circuit that locates in a downstream of a boiler body. Preferably, the spray nozzle is installed to be the same direction with flow of steam in the steam circuit. Moreover, preferably, a blowout angle of an anticorrosion agent blown out from the spray nozzle is made in a range of 60-120 degrees.

Description

  The present invention relates to a corrosion prevention method for steam generating equipment.

  In the steam generation facility, an anticorrosive agent is added for the purpose of preventing corrosion in the system. The types of drugs used for these drugs differ depending on the place where the drug effect is required (for example, water supply system, boiler body, steam system, condensate system).

For example, when performing water supply system corrosion prevention, a canning agent having an anticorrosion function is used.
Moreover, when performing anticorrosion of a boiler main body, in addition to using an oxygen scavenger, means for forming an iron oxide film (magnetite) by adding an organic acid salt is used.

On the other hand, when performing corrosion protection of steam systems and condensate systems, volatile substances typified by neutralizing amines are widely used. The neutralizing amine can prevent corrosion of piping and the like by neutralizing carbonic acid generated in the boiler body.
As long as the volatile substances such as neutralizing amine enter the system of the steam generation facility, they are heated and volatilized into the vapor phase and diffuse uniformly with the steam. It could be added even in the water supply system.
For example, Patent Document 1 describes that a volatile anticorrosive agent is added to the water supply line in the conventional technology column, and a volatile anticorrosive agent is added to the steam pipe and the steam header in the embodiment column of the invention. It is described to be added. Patent Document 1 also describes adding a non-volatile anticorrosive to the downstream side of the steam trap.

On the other hand, when a non-volatile anticorrosive agent is used, even if it is added to the water supply system, it does not shift to the steam system or the condensate system but remains in the boiler can.
Therefore, for example, Patent Document 2 describes that a non-volatile anticorrosive agent (fatty acid salt) is poured into steam or condensate instead of a water supply system.

Japanese Patent Laid-Open No. 2002-257302 JP 2004-85116 A

  In the technique of Patent Document 1, only the use of a volatile substance is considered between the boiler body and the steam trap, and there is a problem that a medicinal effect by a nonvolatile substance cannot be obtained in the section. In addition, Patent Document 1 describes adding a non-volatile substance, but only describes adding a non-volatile substance downstream from the steam trap. No effective means for adding substances is described.

The technique of Patent Document 2 uses a non-volatile substance (fatty acid salt). However, as in Patent Document 1, no effective means for adding a non-volatile substance is described.
As in Patent Documents 1 and 2, when a non-volatile substance is simply added to the steam system, only a small part of the added chemical reaches the end of the steam system through the pipes and pumps for chemical injection. There is a problem that the effect cannot be obtained. Specifically, there are problems such that the drug travels along the inner wall surface of the steam pipe and accumulates at the bottom of the steam pipe, or the drug drops in the form of water droplets from the nozzle.

  Moreover, although the fatty acid salt illustrated as a non-volatile substance by patent document 2 shows a certain amount of anticorrosion effect with respect to a steam condensate type steel material, there exists a problem that corrosivity increases with respect to a copper material on the contrary. .

  The present invention has been made under such circumstances, it is possible to reach the end of the steam system of the non-volatile anticorrosive agent, and to exhibit an excellent anticorrosive effect for both steel and copper materials. An object of the present invention is to provide a method for preventing corrosion of steam generating equipment.

  As a result of intensive studies to achieve the above object, the present inventors have found that a spray nozzle is used as a means for sufficiently diffusing the nonvolatile anticorrosive agent to the end of the steam system, and oil and fat is used as the anticorrosive agent. We have found that anticorrosives including mosquitoes are effective and have solved this problem.

That is, the present invention provides the following [1] to [3].
[1] An anticorrosion method for steam generating equipment, in which an anticorrosive containing fats and oils is jetted from a spray nozzle into a steam system located downstream of the boiler body.
[2] The method for preventing corrosion of steam generation equipment according to [1], wherein the spray nozzle is installed in the same direction as the flow of steam in the steam system.
[3] The method for preventing corrosion of steam generating equipment according to the above [1] or [2], wherein the spray angle of the corrosion inhibitor sprayed from the spray nozzle is in the range of 60 to 120 degrees.
Note that the “steam system” in the present invention refers to steam passages such as steam pipes, steam headers, steam traps, and steam usage destinations such as heat exchangers.

  In the anti-corrosion method of the steam generating facility of the present invention, the anti-corrosive agent containing fats and oils can reach the end of the steam system, and the anti-corrosion effect excellent up to the end of the steam system for both steel and copper materials Can be demonstrated.

It is a figure which shows one Embodiment of the chemical injection method of this invention. It is a figure which shows one Embodiment of the installation state of the spray nozzle to steam piping. It is a figure which shows embodiment of the shape of a spray nozzle.

  The anticorrosion method for steam generating equipment of the present invention is to add an anticorrosive containing fats and oils by spraying from a spray nozzle into a steam system located downstream of the boiler body.

FIG. 1 is a diagram showing an embodiment of a drug injection method of the present invention.
As shown in FIG. 1, in the present invention, an anticorrosive containing fats and oils is sprayed from a spray nozzle and added to a steam system located downstream of the boiler body 1.
Although FIG. 1 shows a once-through steam generation facility, the anticorrosion method of the present invention can be applied not only to a once-through steam generation facility but also to a circulation steam generation facility. However, in the circulation type steam generation facility, it is possible to prevent the non-volatile anticorrosive agent from accumulating in a certain amount or more in the boiler body by intermittent blowing, so the anticorrosion method of the present invention is a once-through steam generation facility. It is suitable to apply to.

<Anticorrosive containing fats and oils>
(Oils and fats)
The fats and oils used in the anticorrosion method of the present invention mean fatty acid triglycerides, diglycerides, monoglycerides and mixtures thereof. In these, the fats and oils which have the triglyceride of a fatty acid as a main component are preferable, and may contain diglyceride, monoglyceride, and free fatty acid. These fats and oils are non-volatile.
As fats and oils, there are plant-based fats and oils and animal-based fats and oils, but plant-based fats and oils are more preferable from the viewpoints of the anticorrosive effect and the prevention of piping blockage trouble. Hereinafter, as a suitable example, vegetable oil and fat will be described as a representative example, but the present invention is not limited thereto.

As plant oils and fats, those mainly composed of triglycerides of saturated or unsaturated higher fatty acids having 8 or more carbon atoms are preferred, and suitable examples thereof include rapeseed oil, sunflower oil, soybean oil, corn oil, sesame oil, olive oil and the like. Is mentioned. The fatty acid component of these vegetable fats and oils contains the following various higher fatty acids (mass%).
-Fatty acid component of rapeseed oil: 1-3% palmitic acid, 0.2-3% stearic acid, 12-18% oleic acid, 3-6% eicosenoic acid, 45-55% erucic acid, 12-16% linoleic acid, Linolenic acid 7-9%, unsaponifiable product 0.6-1.2%
Fatty acid composition of sunflower oil: [palmitic acid, stearic acid, arachidic acid] 8.7 to 14.2%, oleic acid 14.1 to 43.1%, linoleic acid 44.2 to 75.4%, unsken Fatty acid component of soybean oil: Saturated acid 14-16%, oleic acid 16-32%, linoleic acid 47-61%, linolenic acid 6-8%, unsaponified product 0.5-1. 6%
-Fatty acid component of corn oil: palmitic acid 8-12%, stearic acid 2.5-4.5%, oleic acid 19-49%, linoleic acid 34-62%, linolenic acid 0.0-2.9%, Unsaponifiable matter 0.8-2.9%
-Fatty acid composition of sesame oil: 45% linoleic acid, 39% oleic acid
Fatty acid composition of olive oil [from Italy]: palmitic acid 9.2%, stearic acid 2.0%, oleic acid 83.1%, linoleic acid 3.9%
Said fats and oils can be used individually by 1 type or in combination of 2 or more types.

(Anticorrosive)
The anticorrosive agent used in the anticorrosion method of the present invention is preferably the above-described emulsion of fats and oils.
Although there is no restriction | limiting in particular in the method of emulsifying fats and oils and preparing an emulsion, The method of adding the emulsifier which can emulsify fats and oils, knead | mixing and emulsifying is mentioned. The fats and oils concentration and the emulsifier concentration in the emulsion are not particularly limited as long as the emulsion is stable.
As the emulsifier, plant-derived ester emulsifiers, ether-based emulsifiers and the like are preferable, and plant-derived ester-based emulsifiers are more preferable. This plant-derived emulsifier is also preferable from the viewpoint of safety when touching the human body.

As plant-derived ester emulsifiers, glycerin fatty acid esters (fatty acid monoglycerides, fatty acid diglycerides) obtained by heating reaction of vegetable oils and glycerin, sucrose fatty acid esters obtained by transesterification of sucrose and fatty acid methyl esters Sorbitan fatty acid ester obtained by esterifying various fatty acids and sorbitol using alkali as a catalyst, propylene glycol fatty acid ester obtained by esterifying propylene glycol and fatty acid, soybean phospholipid obtained from soybean, polyoxyethylene Examples include fatty acid esters.
These plant-derived ester emulsifiers can be used singly or in combination of two or more.

Examples of a method for preparing an emulsion by emulsifying vegetable oils and fats include a method in which vegetable oils and fats are homogenized in an aqueous medium using a homogenizer in the presence of a plant-derived ester emulsifier. Examples of the homogenizer include a colloid mill, a vibration stirrer, a two-stage high-pressure pump, a high-pressure jet from a nozzle and an orifice, and ultrasonic stirring. Furthermore, the adjustment of the particle size of the oil droplets in the emulsion is influenced by the control of the shearing force during the homogenization process, the amount of the emulsifier, etc., and these can be selected by simple preliminary experiments. .
The size of the oil droplet diameter is a value measured by a dynamic light scattering method, and is preferably about 0.8 to 1000 nm, more preferably 0.8 to 100 nm.

The addition amount of the anticorrosive containing fats and oils is preferably 0.05 to 100 mg / L, more preferably 1 to 50 mg / L with respect to 1 L of the steam flow rate as an active ingredient of fats and oils. By making it 0.05 mg or more, the anticorrosion property becomes better, and by making it 100 mg or less, it is caused by the bubbling of boiler water even if operation with a high concentration factor is performed when it is brought into the boiler can by condensate recovery. Carry over can be prevented.
Moreover, it is preferable to add the anticorrosive containing fats and oils continuously, without stopping.

<Steam system>
The anticorrosive containing fats and oils is ejected into the steam system by a spray nozzle. The steam system is a downstream side of the boiler body and refers to steam pipes, steam headers, steam channels such as a steam trap, and steam usage destinations such as a heat exchanger.
The anticorrosive containing fats and oils is preferably added as upstream as possible in the steam system from the viewpoint of expressing the anticorrosive property in the entire steam system, and from the viewpoint of more uniformly diffusing the chemical components, It is preferable to add an anticorrosive.
Examples of the steam pipe include a pipe connecting the boiler body and the steam header, a pipe connecting the steam header and the steam trap, and a pipe connecting the steam header and the heat exchanger.
If an anticorrosive containing fats and oils is added upstream of the steam header, there is a possibility that a chemical component that has not yet diffused will be discharged from the trap as a drain in the steam header. Therefore, it is preferable to add the anticorrosive containing fats and oils downstream of a steam header, and it is further more preferable to add it in the steam piping downstream of a steam header, and the location close to a steam header.
Moreover, when adding the anticorrosive containing fats and oils to steam piping, it is preferable to add in the straight pipe part of steam piping.

<Spray nozzle>
The spray nozzle 34 is located, for example, at the tip of the chemical injection device 3 including the chemical liquid tank 31, the chemical liquid pipe 32, the pump 33, and the spray nozzle 34, and is used by being inserted into a steam system such as the steam pipe 6 (see FIG. 2 (a)). In addition, a check valve 35 may be installed in front of the spray nozzle 34 as necessary in order to prevent the backflow of steam.
It is preferable to install the spray nozzle in the same direction as the steam flow in the steam system.

The anticorrosive containing fats and oils ejected from the spray nozzle preferably has an ejection angle (θ) of 10 to 180 degrees, more preferably 60 to 120 degrees, from the viewpoint of uniformly diffusing by the steam system. It is preferable (FIG. 2 (b)). Moreover, it is preferable to make small the diameter of the spray particle ejected from a spray nozzle, specifically, it is preferable to set it as 100 micrometers or less, and it is more preferable to set it as 0.1-50 micrometers.
The ejection angle can be adjusted by the shape of the tip of the spray nozzle and the pump pressure, and the spray particle diameter can be adjusted by the pump pressure.

The structure of the spray nozzle is, for example, a one-fluid nozzle (FIG. 3 (a)) that refines droplets by a throttle structure or an orifice structure, and a one-fluid nozzle (FIG. 3 (b) that refines droplets by centrifugal force). )) And a two-fluid nozzle (FIG. 3 (c)) that refines droplets using a high-pressure gas. Among these, a one-fluid nozzle is preferable from the viewpoint of ease of application.
In addition, it is preferable that the front-end | tip of a spray nozzle is opened substantially circularly from a viewpoint of diffusing the anticorrosive containing fats and oils uniformly.

  A conventionally well-known thing can be used for a chemical | medical solution tank, a chemical | medical solution piping, a pump, and a check valve. For example, the pump may be any pump that can be injected at a required pressure, and examples thereof include a diaphragm pump and a plunger pump.

In the present invention, since the anticorrosive agent containing fats and oils is misted and diffused by the spray nozzle, the anticorrosive agent moves in the pipe together with the steam without forming droplets, and has a sufficient anticorrosive effect to the end of the steam system. It can be demonstrated. In addition, the present invention is characterized in that an anticorrosive containing fats and oils which are nonvolatile substances is added by a steam system. That is, even if an anticorrosive containing fats and oils is added using a spray nozzle in the water supply system, boiler body, and condensate system, a sufficient amount of non-volatile substances cannot be delivered to the steam system.
In the present invention, the anticorrosive containing fats and oils can be sent to the condensate system downstream of the steam system, and the condensate system piping and the like can be anticorrosive.

<Volatile anticorrosive>
In the present invention, a volatile anticorrosive may be used in combination as an anticorrosive added to the steam system. Volatile anticorrosives include neutralizers that can prevent corrosion of pipes by neutralizing carbonic acid generated in the boiler body, and prevent condensed water from coming into contact with pipe surfaces. By doing so, long chain aliphatic alkylamines and the like that can prevent corrosion of the pipes can be mentioned.
Neutralizing agents such as ammonia, cyclohexylamine, monoethanolamine, cyclohexylamine, morpholine, diethylethanolamine, monoisopropanolamine, 3-methoxypropylamine, 2-amino-2-methyl-1-propanol Include functional amines.
Long chain aliphatic alkylamines include dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, eicosylamine, docosylamine, oleylamine, ricinoleylamine, Examples thereof include those having 10 to 22 carbon atoms such as linoleylamine and linoleylamine.

<Optional components>
In the present invention, as long as the object of the present invention is not impaired, various additive components, for example, chelating agents, scale inhibitors, volatile, at any point in the system of the steam generating equipment, if necessary. An effective amount of an anticorrosive agent or the like can be added. These additive components can be used alone or in combination of two or more.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

[Example 1]
A small once-through boiler (maximum evaporation: 500 kg / h) having the configuration shown in FIG. 1 was operated at a evaporation pressure of 450 kg / h and a steam pressure of 0.7 MPa using Nogicho water softened water as feed water. Here, the anticorrosive containing fats and oils was inject | poured into the steam piping downstream of a steam header so that an active ingredient might be 10 mg with respect to 1 L of steam flow rates. A spray nozzle (YB1 / 8MN-SS5.5V, manufactured by Spraying Systems Japan Co., Ltd.) was used as a nozzle for injecting oil and fat anticorrosives, and was installed in the same direction as the steam flow. In addition, the spray angle of the anticorrosive from the spray nozzle was 15 degrees. Moreover, the anti-corrosion agent containing fats and oils is vegetable oil emulsion which emulsified 40 mass parts of rapeseed oil in the ratio of 2 mass parts of sorbitan fatty acid ester (the Riken Vitamin Co., Ltd. brand name Riquemar) in 100 mass parts of aqueous medium. Was used.
Under the above conditions, the concentration of the anticorrosive agent was measured and the anticorrosion performance was evaluated.

[Example 2]
Example 1 except that the anticorrosive containing fats and oils was changed to a vegetable oil emulsion in which 20 parts by mass of olive oil was emulsified at a ratio of 5 parts by mass of sorbitan fatty acid ester (Rikemar Riken Vitamin Co., Ltd.) in 100 parts by mass of the aqueous medium. In the same manner as above, the anticorrosive concentration was measured and the anticorrosion performance was evaluated.

[Comparative Example 1]
The anticorrosive concentration was measured and the anticorrosion performance was evaluated in the same manner as in Example 1 except that the spray nozzle was changed to a tube nozzle.

[Reference example]
The anticorrosive concentration was measured and the anticorrosion performance was evaluated in the same manner as in Example 1 except that no nozzle was used and no anticorrosive was added.

<Measurement of anticorrosive concentration>
Steam condensate through the heat exchanger at the end of the steam system (sampling point A), drain from the steam trap before the heat exchanger (sampling point B: discharged at 5.2 kg / h) and steam header drain (sampling point) C: discharged at 3.5 kg / h) was collected, and the concentration of the anticorrosive agent (concentration of fats and oils) in the steam condensed water was measured. The results are shown in Table 1.

<Evaluation of anticorrosion performance>
At sampling point A, steam is continuously collected at 12 kg / h, cooled by a SUS heat exchanger to be 50 ° C. condensed water, and this is a column provided with test pieces made of steel and copper And a corrosion test was conducted for 168 hours under each condition. The test piece after the test was derusted, and the corrosion rate was determined by comparison with the mass before the test. The results are shown in Table 2.

As is clear from the results in Table 1, in the anticorrosion methods of Examples 1 and 2 using a spray nozzle, the amount of the anticorrosive returned to the sampling point C downstream of the location where the anticorrosive was added was small, and the end of the steam path The anticorrosive reached the sampling point A.
Further, as is clear from the results in Table 2, the corrosion prevention methods of Examples 1 and 2 using a spray nozzle and using an anticorrosive containing fats and oils have a slow corrosion rate of steel and copper and have good anticorrosion performance. It was what was. The evaluation of the anticorrosion performance uses the steam collected at the sampling point A as condensed water, so that the anticorrosion method of the present invention can not only prevent corrosion in the steam system, but also protect the condensate system at the end of the steam system. It is shown that.
On the other hand, since the anticorrosion method of Comparative Example 1 uses a tube-shaped nozzle, most of the anticorrosive agent returns to the sampling point C, and the anticorrosive agent does not reach the end of the above path, so that the anticorrosion performance is improved. It was inferior.

1: Boiler body 2: Steam header 3: Chemical injection device 31: Chemical injection tank 32: Chemical injection piping 33: Pump 34: Spray nozzle 4: Steam trap 5: Heat exchanger 6: Steam piping

Claims (3)

  An anticorrosion method for steam generating equipment, in which an anticorrosive containing fats and oils is jetted from a spray nozzle into a steam system located downstream of the boiler body.   The corrosion prevention method for steam generating equipment according to claim 1, wherein the spray nozzle is installed so as to be in the same direction as the flow of steam in the steam system.   The anticorrosion method for steam generating equipment according to claim 1 or 2, wherein the spray angle of the anticorrosive sprayed from the spray nozzle is in the range of 60 to 120 degrees.

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