Turbine oil regeneration method

Abstract

To provide a regeneration method of a turbine oil capable of achieving anticorrosive property and antioxidation property in good balance.SOLUTION: A regeneration method of a used turbine oil includes the steps of: removing degraded components from a used turbine oil; and adding an anticorrosive agent and an antioxidation agent to a regenerated turbine oil obtained by the removal step, wherein an addition amount of the anticorrosive agent is 0.01-0.04 mass% to the mass of the regenerated turbine oil, and an addition amount of the antioxidation agent is a mass in a range of concentration predetermined corresponding to kinds of the antioxidation agent.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for regenerating turbine oil used as lubricating oil in steam turbines and gas turbines.

Background Art

[0002] Patent Document 1 describes turbine oil containing additives such as a rust inhibitor. The concentration of the rust inhibitor in this turbine oil is 0.01 to 10.0% by mass.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The turbine oil of Patent Document 1 has the composition of turbine oil as new oil. When regenerating and reusing used turbine oil, in the regeneration of used turbine oil, it is necessary to add additives after removing deteriorated components from the used turbine oil. Examples of the additives include a rust inhibitor, an antioxidant, an antifoaming agent, etc. However, it is known that the rust inhibitor reduces the antioxidant performance of the antioxidant. Therefore, when adding a rust inhibitor and an antioxidant in regenerating used turbine oil, it is required to achieve both rust prevention performance and antioxidant performance.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a method for regenerating turbine oil in which rust prevention performance and antioxidant performance can be achieved simultaneously.

Means for Solving the Problems

[0006] To achieve the above objective, the turbine oil regeneration method according to the present disclosure is a method for regenerating used turbine oil, comprising: a removal step of removing deteriorated components from the used turbine oil; and an addition step of adding a rust inhibitor and an antioxidant to the regenerated turbine oil obtained in the removal step, wherein the amount of the rust inhibitor added is 0.01 to 0.04% by mass of the regenerated turbine oil, and the amount of the antioxidant added is For each type of antioxidant, the proportional relationship between the concentration of the antioxidant in the regenerated turbine oil and the RPVOT value of the regenerated turbine oil is determined, and based on this proportional relationship, It is mass. [Effects of the Invention]

[0007] According to the turbine oil regeneration method of this disclosure, a rust inhibitor and an antioxidant are added to regenerated turbine oil obtained by removing deteriorated components from used turbine oil, and the amount of rust inhibitor added is 0.01 to 0.04% of the mass of the regenerated turbine oil, thereby enabling the regeneration of turbine oil that can achieve both rust prevention and oxidation prevention performance. [Brief explanation of the drawing]

[0008] [Figure 1] This flowchart outlines the turbine oil regeneration method described herein. [Figure 2] This graph shows experimental results regarding the relationship between the concentration of rust inhibitors in recycled turbine oil and the recovery rate of the RPVOT value. [Figure 3] This graph shows experimental results regarding the relationship between the concentration of rust inhibitors in recycled turbine oil and the rate of decrease in RPVOT value. [Figure 4] This flowchart outlines an embodiment of the turbine oil regeneration method of this disclosure that includes a step for determining the completion of regeneration. [Figure 5] This graph shows experimental results illustrating the relationship between the concentration of antioxidants in turbine oil and the RPVOT value. [Modes for carrying out the invention]

[0009] A method for regenerating turbine oil according to embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below represent one aspect of this disclosure and are not limiting, and can be modified at will within the scope of the technical idea of ​​this disclosure.

[0010] <Method for regenerating turbine oil according to this disclosure> The turbine oil regenerated by the turbine oil regeneration method disclosed herein is used turbine oil that has been used as a lubricant in steam turbines and gas turbines. Used turbine oil deteriorates and comes to contain degradation components such as organic acids such as carboxylic acids, causing it to change color to a brownish-red. Used turbine oil is regenerated by removing the degradation components, and the regenerated turbine oil becomes transparent. This regeneration method can be performed in batches during regular inspections of steam turbines and gas turbines, or it can be used to continuously extract and regenerate used turbine oil while the steam turbine or gas turbine is in operation.

[0011] As shown in Figure 1, the turbine oil regeneration method of this disclosure first involves removing degraded components from used turbine oil (removal step S1). In removal step S1, the used turbine oil and an adsorbent such as silica gel are brought into contact, for example, by adding the used turbine oil and an adsorbent such as silica gel to a stirring tank and stirring, or by passing the used turbine oil through a column packed with an adsorbent. Through this contact, the degraded components contained in the used turbine oil are adsorbed by the adsorbent, and the degraded components are removed from the used turbine oil. As a result, the used turbine oil becomes regenerated turbine oil.

[0012] Used turbine oil contains various additives in addition to degradation components. Therefore, when used turbine oil comes into contact with an adsorbent, not only the degradation components but also the additives are adsorbed by the adsorbent. As a result, the additive content in the recycled turbine oil decreases compared to the turbine oil used in steam turbines and gas turbines. Therefore, after the removal step S1, rust inhibitors and antioxidants are added to the recycled turbine oil (addition step S2). In addition to rust inhibitors and antioxidants, an antifoaming agent can also be added to the recycled turbine oil in addition step S2. The purpose of addition step S2 is to add back the additives that are removed from the used turbine oil in the removal step S1.

[0013] As rust inhibitors, for example, metal sulfonates, alkylbenzene sulfonates, dinonyl naphthalene sulfonates, organic phosphites, organic phosphates, metal organic sulfonic acid salts, metal organic phosphate salts, alkenyl succinates, and polyhydric alcohol esters of alkenyl succinates can be used. As antioxidants, for example, phenolic antioxidants, amine antioxidants, or mixtures thereof can be used. As defoaming agents, for example, silicone-based defoaming agents, fluorine-based defoaming agents, and polyacrylate-based defoaming agents can be used.

[0014] The inventors of this disclosure investigated the appropriate amount of rust inhibitor to be added to the regenerated turbine oil in addition step S2. The inventors prepared six samples: 500 mL of distilled water and 500 mL of distilled water with concentrations of the rust inhibitor Sanhibiter 150 (Sanyo Chemical Industries, Ltd.) at 0.01% by mass, 0.02% by mass, 0.03% by mass, 0.04% by mass, and 0.06% by mass. Rust inhibition tests were performed on these samples in accordance with JIS K 2510. As a result, sufficient rust inhibition performance was not observed for the distilled water, but sufficient rust inhibition performance was observed for the distilled aqueous solutions of rust inhibitor at concentrations of 0.01 to 0.06% by mass.

[0015] The RPVOT value (ASTM D 2272) is commonly used as an indicator of the oxidation stability of turbine oil. The timing of turbine oil replacement and regeneration can be determined based on the RPVOT value. The inventors of this disclosure measured the RPVOT values ​​for four samples: three samples in which a rust inhibitor was added to the regenerated turbine oil obtained by removal step S1, with rust inhibitor concentrations of 0.03% by mass, 0.04% by mass, and 0.05% by mass; and a regenerated turbine oil without rust inhibitor, to which the antioxidant butylhydroxytoluene (Tokyo Chemical Industries, Ltd.) was added to a concentration of 0.72% by mass. In addition, the RPVOT values ​​were measured for two samples in which a rust inhibitor was added to the regenerated turbine oil obtained by removal step S1, with rust inhibitor concentrations of 0.03% by mass and 0.06% by mass, to which the antioxidant was added to a concentration of 0.76% by mass. Figure 2 shows the test results for these samples as a graph with the horizontal axis representing the concentration of rust inhibitor in the regenerated turbine oil and the vertical axis representing the RPVOT recovery rate (%), which is the ratio of the RPVOT value of each sample to the RPVOT value of the used turbine oil. In Figure 2, the circular plots show the test results for the sample with an antioxidant concentration of 0.72 mass%, and the square plots show the test results for the sample with an antioxidant concentration of 0.76 mass%. From these results, it was found that even with different antioxidant concentrations, the RPVOT recovery rate decreases as the concentration of rust inhibitor in the regenerated turbine oil increases.

[0016] Furthermore, the inventors of this disclosure performed a Dry-Turbine Oil Oxidation Stability Test (Dry-TOST) on four samples: two samples obtained by adding a rust inhibitor to the regenerated turbine oil obtained by removal step S1, with rust inhibitor concentrations of 0.03% and 0.06% by mass, and two samples of regenerated turbine oil without the rust inhibitor. These samples were prepared using the Dry-TOST test described in Japanese Patent Publication No. 2015-059866, published by the applicant of this disclosure. Dry-TOST is a modified version of the Turbine Oil Oxidation Stability Test (TOST) specified in the JIS standard (JIS K 2514), with the oil bath temperature changed to 120°C. Figure 3 shows the test results for these samples as a graph with the concentration of the rust inhibitor in the regenerated turbine oil on the horizontal axis and the rate of decrease in RPVOT value (min / hr) on the vertical axis. The results show that the concentration of the rust inhibitor in the regenerated turbine oil had almost no effect on the rate of decrease in RPVOT value.

[0017] Based on the above-mentioned findings by the inventors of this disclosure, it is considered that the amount of rust inhibitor added to the regenerated turbine oil does not need to be determined based on the relationship between the concentration of the rust inhibitor in the regenerated turbine oil and the rate of decrease in the RPVOT value, but rather on the relationship between the concentration of the rust inhibitor in the regenerated turbine oil and the recovery rate of the RPVOT value. Therefore, the inventors of this disclosure set the amount of rust inhibitor added to the regenerated turbine oil in addition step S2 to be 0.01 to 0.04% of the mass of the regenerated turbine oil, as a condition for obtaining a recovery rate of 90% or more of the RPVOT value and sufficient rust prevention performance.

[0018] Regarding the addition amount of the antioxidant, it is the mass at a concentration within a range determined in advance according to the type of the antioxidant. Assuming that all the antioxidants in the used turbine oil are removed in the removal step S1, the same amount of antioxidant as the amount initially contained in the turbine oil may be added in the addition step S2. Further, after the removal step S1, the content of the antioxidant in the regenerated turbine oil may be measured, and an amount of antioxidant corresponding to the difference between the amount initially contained in the turbine oil and the measured value may be added in the addition step S2. The concentration of the antioxidant in the turbine oil can be measured, for example, by Fourier transform infrared spectroscopy (FT-IR). Specifically, a plurality of samples of turbine oil with different antioxidant concentrations are prepared, and the absorbance of these samples is measured by FT-IR to create a calibration curve showing the relationship between the antioxidant concentration and the absorbance in advance. The absorbance of the used turbine oil or the regenerated turbine oil is measured by FT-IR, and the concentration of the antioxidant can be measured from the measured value of the absorbance based on this calibration curve.

[0019] In this way, by adding an anti-corrosion agent and an antioxidant to the regenerated turbine oil from which the deteriorated components have been removed from the used turbine oil, and the addition amount of the anti-corrosion agent is 0.01 to 0.04% by mass based on the mass of the regenerated turbine oil, it is possible to regenerate a turbine oil that can achieve both anti-corrosion performance and antioxidant performance. <000,0091>

[0020] The regenerated turbine oil obtained by the removal step S1 and the addition step S2 can also be reused as a lubricating oil in a steam turbine or a gas turbine. However, in order to obtain anti-corrosion performance without significantly reducing the RPVOT value with respect to the used turbine oil, an operation described below may be added after the addition step S2.

[0021] As shown in FIG. 4, after the addition step S2, the RPVOT value of the regenerated turbine oil is measured (measurement step S3). As described above, the higher the concentration of the anti-corrosion agent in the regenerated turbine, the lower the recovery rate of the PRVOT value. For example, if the amount of the anti-corrosion agent added in the addition step S2 is too large with respect to the amount of the anti-corrosion agent removed in the removal step S1, the concentration of the anti-corrosion agent in the regenerated turbine oil after the addition step S2 may exceed 0.04% by mass, and the recovery rate of the PRVOT value may be considered to be less than 90%.

[0022] On the other hand, in the study by the inventors of the present disclosure (using butylhydroxytoluene as an antioxidant), as shown in FIG. 5, it was recognized that there is a proportional relationship between the concentration of the antioxidant in the regenerated turbine oil and the RPVOT value. Therefore, for each type of antioxidant, this proportional relationship (for example, the proportional constant obtained by dividing the RPVOT value by the concentration of the antioxidant) is determined in advance, and by additionally adding an appropriate amount of the antioxidant to the regenerated turbine oil based on this proportional relationship, the recovery rate of the PRVOT value can be increased.

[0023] Therefore, after the measurement step S3, it is determined whether it is necessary to additionally add an antioxidant to the regenerated turbine oil based on the RPVOT value measured in the measurement step S3 (determination step S4). For example, a lower limit value for the recovery rate of the PRVOT value is set in advance (for example, 90%), the recovery rate of the PRVOT value calculated from the RPVOT value measured in the measurement step S3 is compared with this lower limit value, and if the former is lower than the latter, it is determined that it is necessary to additionally add an antioxidant to the regenerated turbine oil.

[0024] If it is determined in the determination step S4 that it is necessary to add antioxidants to the regenerated turbine oil, the amount of antioxidant to be added is determined based on the RPVOT value measured in the measurement step S3 (determination step S5). For example, based on the proportional relationship between the concentration of the antioxidant and the RPVOT value, which has been determined in advance for each type of antioxidant, the amount of antioxidant to be added can be calculated from the difference between the RPVOT value measured in the measurement step S3 and the lower limit. Once the amount of antioxidant to be added is determined, that amount of antioxidant is added to the regenerated turbine oil (addition step S6).

[0025] By performing steps S3 through S6 (measurement step to additional addition step) after the removal step S1 and addition step S2, even if the amount of rust inhibitor added to the regenerated turbine oil is too high and the RPVOT value becomes low, the RPVOT value can be increased by adding an additional antioxidant.

[0026] The contents described in each of the above embodiments can be understood, for example, as follows:

[0027] [1] A method for regenerating turbine oil according to one embodiment is: A method for recycling used turbine oil, A removal step to remove degraded components from the used turbine oil, Addition step: Adding a rust inhibitor and an antioxidant to the recycled turbine oil obtained in the removal step. Includes, The amount of rust inhibitor added is 0.01 to 0.04% of the mass of the recycled turbine oil, and the amount of antioxidant added is a mass that results in a concentration within a predetermined range depending on the type of antioxidant.

[0028] According to the turbine oil regeneration method of this disclosure, a rust inhibitor and an antioxidant are added to regenerated turbine oil obtained by removing deteriorated components from used turbine oil, and the amount of rust inhibitor added is 0.01 to 0.04% of the mass of the regenerated turbine oil, thereby enabling the regeneration of turbine oil that can achieve both rust prevention and oxidation prevention performance.

[0029] [2] A turbine oil regeneration method according to another embodiment is the turbine oil regeneration method of [1], A measurement step of measuring the RPVOT value of the recycled turbine oil to which the rust inhibitor and the antioxidant have been added, A determination step, based on the RPVOT value measured in the measurement step, determines whether or not it is necessary to add the antioxidant to the regenerated turbine oil. If the determination step determines that it is necessary to add the antioxidant further, the determination step determines the amount of the antioxidant to be added based on the RPVOT value measured in the measurement step, The additional addition step involves adding the amount of antioxidant determined in the determination step to the regenerated turbine oil. Includes.

[0030] With this regeneration method, even if the amount of rust inhibitor added to the regenerated turbine oil is too high and the RPVOT value becomes low, the RPVOT value can be increased by adding more antioxidants.

Claims

1. A method for recycling used turbine oil, A removal step to remove degraded components from the used turbine oil, Addition step: Adding a rust inhibitor and an antioxidant to the recycled turbine oil obtained in the removal step. Includes, A method for regenerating turbine oil, wherein the amount of rust inhibitor added is 0.01 to 0.04% of the mass of the regenerated turbine oil, and the amount of antioxidant added is determined by determining the proportional relationship between the concentration of the antioxidant in the regenerated turbine oil and the RPVOT value of the regenerated turbine oil for each type of antioxidant, and the mass determined based on this proportional relationship.

2. A measurement step of measuring the RPVOT value of the regenerated turbine oil to which the rust inhibitor and the antioxidant have been added, A determination step, based on the RPVOT value measured in the measurement step, determines whether or not it is necessary to add the antioxidant to the regenerated turbine oil. If the determination step determines that it is necessary to add the antioxidant further, the determination step determines the amount of the antioxidant to be added based on the RPVOT value measured in the measurement step, The additional addition step involves adding the amount of antioxidant determined in the determination step to the regenerated turbine oil. A method for regenerating turbine oil according to claim 1, including the following:

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