Process for preventing high-temperature coking of bearing bush

Abstract

The invention relates to the technical field of air compressors, and provides a process for preventing high-temperature coking of a bearing bush, which comprises the following steps: S1, stopping compressor equipment, opening the bearing bush, and comprehensively cleaning a paint film on the surface of the bearing bush; s2, the oil tank is opened, engine oil is fully removed, sediments on the surface of the oil tank, an electric heater in the oil tank and the like are comprehensively cleaned, and the sediments need to be fully cleaned to prevent residues; s3, after a bearing bush is cleaned up, old oil is discharged, and an oil system is cleaned up, lubricating oil containing synthetic base oil and a polar substance dissolution enhancing formula is selected to be injected into equipment for normal operation; and S4, carrying out closed-loop monitoring on the equipment. According to the invention, by adopting the lubricating oil (Mu SHC846Ultraa) containing the synthetic base oil and a polar substance dissolution enhancing formula, the problem of high-temperature coking is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of air compressors, and specifically, to a process for preventing high-temperature coking of bearing bushes. Background Art

[0002] For large centrifugal compressors (such as six-stage air separation compressors) under high-pressure and high-speed ( > 17000 rpm) operating conditions, the bearing bushes are prone to film deposition due to thermal degradation of lubricating oil, resulting in an increase in bearing bush temperature ( > 110°C) and aggravated vibration.

[0003] To alleviate the formation of the film, the solutions in the prior art include adjusting the bearing bush clearance, increasing the lubricating oil flow rate, etc., but the effects are limited. Since mineral lubricating oil (such as Mobil DTE846) has poor antioxidant properties and low solubility of polar substances, it is difficult to inhibit the formation of the film. Therefore, a systematic process is urgently needed to comprehensively solve this problem from the dimensions of lubricating oil performance, cleaning and maintenance, and monitoring. Summary of the Invention

[0004] The present invention proposes a process for preventing high-temperature coking of bearing bushes, which solves the problem of difficult high-temperature coking of bearing bushes in the prior art.

[0005] The technical solution of the present invention is as follows: A process for preventing high-temperature coking of bearing bushes includes the following steps:

[0006] S1. Stop the compressor equipment, open the bearing bushes, and comprehensively clean the film on the surface of the bearing bushes.

[0007] S2. Open the oil tank, fully drain the engine oil, and comprehensively clean the deposits on the surface of the oil tank, the electric heater in the oil tank, etc., and it is necessary to clean thoroughly to prevent residues.

[0008] S3. After the bearing bushes are cleaned, the old oil is drained, and the oil system is cleaned, select a lubricating oil containing a synthetic base oil and a formula for enhancing the solubility of polar substances, fill it into the equipment to the standard liquid level, and monitor the stability of the oil pressure and temperature after starting the equipment to ensure no cavitation and abnormal foaming.

[0009] S4. Conduct closed-loop monitoring on the equipment, including the following monitoring schemes:

[0010] A1. Take samples of the lubricating oil every quarter to track and detect comprehensive indicators.

[0011] A2. Regularly track the operating temperature of the compressor bearing bushes.

[0012] A3. Disassemble and inspect the actual situation of the bearing bushes after 1 year of use.

[0013] Preferably, in S1, the paint film on the bearing shell surface is cleaned by solvent cleaning and physical polishing to ensure that the roughness Ra ≤ 0.4 μm.

[0014] Preferably, in S2, the oil system is circulated and rinsed with a low-residue cleaning agent until the particle size of the rinsing liquid ≤ NAS 8 level.

[0015] Preferably, in S3, the lubricating oil is Mobil SHC846 Ultra, and its properties meet the requirements that the oxidation stability by rotating oxygen bomb method ≥ 3000 minutes, the viscosity index ≥ 130, and the paint film index (MPC) ≤ 2.

[0016] Preferably, in S4, the comprehensive indicators of the lubricating oil are sampled and tracked quarterly, including the lubricating oil viscosity, total acid value, and paint film index.

[0017] Preferably, the specific implementation process of the lubricating oil viscosity detection is as follows:

[0018] B1. Calibrate the capillary viscometer with standard viscosity oil, and the error should be < ±1%, confirm that the temperature of the constant temperature bath is stable at 40 °C, and the fluctuation ≤ ±0.1 °C;

[0019] B2. Vertically immerse the clean and dry capillary viscometer into the constant temperature bath, and then use a syringe to suck the oil sample and inject it from the wide end of the viscometer to the marking line;

[0020] B3. Keep constant temperature for 15 - 20 minutes to ensure that the temperature of the oil sample is consistent with the bath;

[0021] B4. Use a rubber ball or pipette bulb to suck the oil sample into the upper liquid storage ball of the capillary, release the oil sample to flow freely, record the time t when the liquid level passes through the upper and lower marking lines, repeat 3 times and take the average value, and calculate the kinematic viscosity v through the following formula:

[0022] v = C·t;

[0023] where C is the capillary constant.

[0024] Preferably, the specific implementation process of the total acid value detection of the lubricating oil is as follows:

[0025] C1. Calibrate the electrode with pH 4.0 and 7.0 buffer solutions, and the slope should be within the range of 95 - 105%. If the electrode response is abnormal, clean or replace the electrode and recalibrate;

[0026] C2. Transfer the diluted oil sample to the titration cup and add a magnetic stir bar;

[0027] C3. Start the titrator, automatically record the consumption volume V1 of the KOH solution, perform a blank titration with the solvent instead of the oil sample and record the consumption volume V0 of the KOH solution, and determine the end point when the potential change rate < 0.5 mV / s;

[0028] C4. Calculate the total acid number TAN using the following formula:

[0029] TAN = (V1 - V0) × C KOH × 56.1;

[0030] m 样品

[0031] where C KOH is the concentration of the KOH solution (mol / L), m 样品 is the mass of the oil sample (g), and 56.1 is the molar mass of KOH (g / mol).

[0032] Preferably, the specific implementation process of the film index detection is as follows:

[0033] D1. Place the filter membrane into the filtering funnel, moisten it with n - heptane and evacuate for 30 seconds to remove the residual solvent, and record the initial color of the filter membrane.

[0034] D2. Measure 10 mL of the oil sample, add 40 mL of n - heptane, and stir until completely dissolved to obtain a mixed solution.

[0035] D3. Pour the mixed solution into the filtering funnel, start the vacuum pump and slowly filter until a uniform deposit is formed on the surface of the membrane, and rinse the inner wall of the funnel with 10 mL of n - heptane to ensure that the polar substances are completely adsorbed on the membrane.

[0036] D4. Turn off the vacuum pump, carefully remove the membrane, lay it flat on a dust - free filter paper, and then dry it at room temperature for 30 minutes, and observe the color change of the membrane.

[0037] D5. Use a spectrophotometer to measure the absorbance of the membrane at a wavelength of 465 nm, and calculate the MPC value according to the standard curve.

[0038] The working principle and beneficial effects of the present invention are as follows:

[0039] 1. By using a lubricating oil (Mobil SHC846 Ultra) containing a synthetic base oil and a polar substance dissolution enhancement formula, its oxidation stability by the rotating oxygen bomb method ≥ 3000 minutes, viscosity index ≥ 130, film index (MPC) ≤ 2, significantly improving the antioxidant property and the ability to dissolve polar substances. The test data shows that after using this lubricating oil, the film index maintains MPC < 5. Compared with mineral oil (Mobil DTE846), the film deposition on the bearing bush is significantly reduced after the equipment runs for 11000 hours, effectively solving the problem of high - temperature coking.

[0040] 2. Strict cleaning steps in the process (such as the roughness of the bearing bush Ra ≤ 0.4 μm, and the oil circuit is flushed until the particle size ≤ NAS 8 level) and the closed-loop monitoring mechanism reduce the risk of friction loss and thermal degradation. The examples show that the operating temperature of the bearing bush drops from ≥ 110 °C to ≤ 105 °C, and the vibration value ≤ 4.5 mm / s RMS, reducing mechanical damage caused by high temperature and vibration, and extending the service life of the compressor;

[0041] 3. The high stability of the synthetic lubricating oil reduces the oil change frequency, and the closed-loop monitoring mechanism reduces the risk of sudden failures. In the test example, the synthetic oil equipment still maintains good condition after running for one year, while the mineral oil equipment needs frequent maintenance due to severe paint film, and the comprehensive maintenance cost is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0043] Figure 1 It is a flowchart of a process for preventing high-temperature coking of a bearing bush according to the present invention;

[0044] Figure 2 It is a broken line graph showing the change of the paint film index of the lubricating oil in each quarter of a year in Test Example 1 of the present invention;

[0045] Figure 3 It is a diagram showing the state of the paint film on the bearing bush after the equipment using Mobil DTE 846 mineral lubricating oil in Test Example 2 of the present invention has run for 11,000 hours;

[0046] Figure 4 It is a diagram showing the state of the paint film on the bearing bush after the equipment using Mobil SHC 846 Ultra lubricating oil in Test Example 2 of the present invention has run for 11,000 hours. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of the present invention.

[0048] Example 1:

[0049] As Figure 1 shown, this example proposes a process for preventing high-temperature coking of a bearing bush, including the following steps:

[0050] S1. The compressor equipment is shut down, the bearing bush is opened, and the paint film on the surface of the bearing bush is comprehensively cleaned by solvent cleaning and physical grinding to ensure that the roughness Ra is 0.4 μm;

[0051] S2. Open the fuel tank, fully drain the engine oil, and comprehensively clean the sediments on the surface of the fuel tank, the electric heater in the fuel tank, etc. It is necessary to clean thoroughly to prevent residues. Use a low-residue cleaning agent to circulate and flush the oil circuit in the oil system until the particle size of the flushing liquid reaches NAS 8 level;

[0052] S3. After the bearing shells are cleaned, the old oil is drained, and the oil system is cleaned, select Mobil SHC846 Ultra lubricating oil and fill it into the equipment to the standard liquid level. After starting the equipment, monitor the stability of oil pressure and temperature to ensure no cavitation and abnormal foaming;

[0053] S4. Conduct closed-loop monitoring on the equipment, including the following monitoring plans:

[0054] A1. Take samples of the lubricating oil every quarter for tracking and detecting comprehensive indicators, including lubricating oil viscosity, total acid value, and film index;

[0055] A2. Regularly track the operating temperature of the compressor bearing shells, with the target ≤ 105°C and the vibration value ≤ 4.5 mm / s RMS. Trigger an alarm when the threshold is exceeded;

[0056] A3. After using for 1 year, disassemble the equipment to check the actual situation of the bearing shells and evaluate the degree of film deposition.

[0057] Example 2:

[0058] This example proposes a process for preventing high-temperature coking of bearing shells, including the following steps:

[0059] S1. Stop the compressor equipment, open the bearing shells, and use solvent cleaning and physical grinding to comprehensively clean the film on the surface of the bearing shells to ensure that the roughness Ra is 0.3 μm;

[0060] S2. Open the fuel tank, fully drain the engine oil, and comprehensively clean the sediments on the surface of the fuel tank, the electric heater in the fuel tank, etc. It is necessary to clean thoroughly to prevent residues. Use a low-residue cleaning agent to circulate and flush the oil circuit in the oil system until the particle size of the flushing liquid reaches NAS 7 level;

[0061] S3. After the bearing shells are cleaned, the old oil is drained, and the oil system is cleaned, select Mobil SHC846 Ultra lubricating oil and fill it into the equipment to the standard liquid level. After starting the equipment, monitor the stability of oil pressure and temperature to ensure no cavitation and abnormal foaming;

[0062] S4. Conduct closed-loop monitoring on the equipment, including the following monitoring plans:

[0063] A1. Take samples of the lubricating oil every quarter for tracking and detecting comprehensive indicators, including lubricating oil viscosity, total acid value, and film index;

[0064] A2. Regularly track the operating temperature of the compressor bearing bush, with the target ≤ 105 °C and the vibration value ≤ 4.5 mm / s RMS. Trigger an early warning when the threshold is exceeded.

[0065] A3. After 1 year of use, disassemble the machine to check the actual situation of the bearing bush and evaluate the degree of paint film deposition.

[0066] Example Three:

[0067] This example proposes a process for preventing high-temperature coking of the bearing bush, including the following steps:

[0068] S1. Stop the compressor equipment, open the bearing bush, and use solvent cleaning and physical grinding to comprehensively clean the paint film on the surface of the bearing bush to ensure that the roughness Ra is 0.2 μm.

[0069] S2. Open the fuel tank, fully drain the engine oil, and comprehensively clean the deposits on the surface of the fuel tank, the electric heater in the fuel tank, etc. It is necessary to clean thoroughly to prevent residues. Use a low-residue cleaning agent to circulate and flush the oil circuit in the oil system until the particle size of the flushing liquid is NAS 6 level.

[0070] S3. After the bearing bush is cleaned, the old oil is drained, and the oil system is cleaned, select Mobil SHC846 Ultra lubricating oil and fill it into the equipment to the standard level. After starting the equipment, monitor the stability of the oil pressure and temperature to ensure no cavitation and abnormal foaming.

[0071] S4. Conduct closed-loop monitoring of the equipment, including the following monitoring plans:

[0072] A1. Quarterly, take samples of the lubricating oil for tracking and testing comprehensive indicators, including lubricating oil viscosity, total acid value, and paint film index.

[0073] A2. Regularly track the operating temperature of the compressor bearing bush, with the target ≤ 105 °C and the vibration value ≤ 4.5 mm / s RMS. Trigger an early warning when the threshold is exceeded.

[0074] A3. After 1 year of use, disassemble the machine to check the actual situation of the bearing bush and evaluate the degree of paint film deposition.

[0075] Comparative Example:

[0076] This comparative example proposes a process for preventing high-temperature coking of the bearing bush. The specific steps are basically the same as those in Example One, except that after the bearing bush is cleaned, the old oil is drained, and the oil system is cleaned, select Mobil DTE846 lubricating oil and fill it into the equipment to the standard level. After starting the equipment, monitor the stability of the oil pressure and temperature to ensure no cavitation and abnormal foaming.

[0077] Test Example One:

[0078] This test example is used to test the film index of the lubricating oil sampled quarterly during the one-year operation of the compressor equipment in Example 1 and the comparative example. The specific test results are as Figure 2 shown;

[0079] As Figure 2 can be seen, for the Mobil SHC 846Ultra lubricating oil used in Example 1, the final MPC of the film index is less than 5 within one year, indicating that the oil product is clean and the film risk is low when using this lubricating oil.

[0080] Test Example 2:

[0081] This test example is used to test the film condition of the bearing bush after the compressor equipment in Example 1 and the comparative example has run for 11,000 hours. The result is that when using Mobil DTE846 mineral lubricating oil, when the equipment runs for about 11,000 hours, the equipment has a high-temperature situation, reaching 110 °C. After disassembling the machine, it is found that the film condition on the bearing bush is relatively serious, as Figure 3 shown;

[0082] After the equipment using Mobil SHC 846Ultra lubricating oil has run for 11,000 hours, the film effect is significantly improved and the bearing bush temperature drops, as Figure 4 shown.

[0083] In summary, Mobil SHC 846Ultra can not only effectively resist the oxidation and thermal degradation processes of the oil product, but also effectively dissolve the polar substances in the oil product. Therefore, this product has excellent anti-thermal degradation or anti-oxidation performance and excellent cleanliness retention performance, and at the same time has excellent sediment control and film control performance. Compared with Mobil DTE 846, the comprehensive performance of Mobil SHC846Ultra has been greatly improved, especially in terms of anti-wear protection and film control.

[0084] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preventing high-temperature coking of bearing shells, characterized in that, It includes the following steps: S1. Stop the compressor equipment, open the bearing bush, and comprehensively clean the paint film on the surface of the bearing bush; S2. Open the oil tank, fully drain the engine oil, and comprehensively clean the deposits on the surface of the oil tank, the electric heater in the oil tank, etc., and it is necessary to clean it thoroughly to prevent residues; S3. After the bearing bush is cleaned, the old oil is discharged, and the oil system is cleaned, select a lubricating oil containing a synthetic base oil and a formula for enhancing the dissolution of polar substances and fill it into the equipment to the standard liquid level. After starting the equipment, monitor the stability of the oil pressure and temperature to ensure no cavitation and abnormal foaming; S4. Conduct closed-loop monitoring on the equipment, including the following monitoring schemes: A1. Take samples of the lubricating oil for tracking and detecting comprehensive indicators every quarter; A2. Regularly track the operating temperature of the compressor bearing bush; A3. Disassemble and inspect the actual situation of the bearing bush after 1 year of use.

2. The process for preventing high-temperature coking of the bearing bush according to claim 1, characterized in that, In S1, the paint film on the surface of the bearing bush is cleaned by solvent cleaning and physical polishing to ensure that the surface roughness Ra ≤ 0.4 μm.

3. A process for preventing high-temperature coking of a bearing bush according to claim 1, characterized in that, In S2, the oil system is flushed with a low-residue cleaning agent in a circulating manner until the particle size of the flushing liquid ≤ NAS 8 level.

4. A process for preventing high-temperature coking of a bearing shell according to claim 1, characterized in that, In S3, the lubricating oil is Mobil SHC 846 Ultra, and its characteristics meet the requirements that the oxidation stability by the rotating oxygen bomb method ≥ 3000 minutes, the viscosity index ≥ 130, and the paint film index (MPC) ≤ 2.

5. A process for preventing high-temperature coking of a bearing bush according to claim 1, characterized in that, In S4, the comprehensive indicators for sampling and tracking detection of the lubricating oil every quarter include the viscosity of the lubricating oil, the total acid value, and the paint film index.

6. A process for preventing high-temperature coking of a bearing bush according to claim 5, characterized in that, The specific implementation process of the viscosity detection of the lubricating oil is as follows: B1. Calibrate the capillary viscometer with a standard viscosity oil, and the error should be < ±1%. Confirm that the temperature of the constant temperature bath is stable at 40 °C, and the fluctuation ≤ ±0.1 °C; B2. Vertically immerse the clean and dry capillary viscometer into the constant temperature bath, and then use a syringe to suck the oil sample and inject it into the viscometer from the wide end to the calibration line; B3. Keep it at a constant temperature for 15 - 20 minutes to ensure that the temperature of the oil sample is the same as that of the bath; B4. Use a rubber ball or an ear syringe to suck the oil sample into the upper liquid storage ball of the capillary, release the oil sample to flow freely, record the time t when the liquid level passes through the upper and lower calibration lines, repeat 3 times and take the average value, and calculate the kinematic viscosity v through the following formula: ； where C is the capillary constant.

7. A process for preventing high-temperature coking of a bearing bush according to claim 5, characterized in that, The specific implementation process of the total acid value detection of the lubricating oil is as follows: C1. Calibrate the electrode with pH 4.0 and 7.0 buffer solutions, and the slope should be in the range of 95 - 105%. If the electrode response is abnormal, it is necessary to clean or replace the electrode and recalibrate; C2. Transfer the diluted oil sample to the titration cup and add a magnetic stir bar; C3. Start the titrator, automatically record the consumption volume V1 of the KOH solution, conduct a blank titration with a solvent instead of the oil sample and record the consumption volume V0 of the KOH solution, and determine the end point when the potential change rate < 0.5 mV / s; C4. Calculate the total acid value TAN through the following formula: ； wherein, is the concentration of KOH solution (mol / L), is the mass of the oil sample (g), is the molar mass of KOH (g / mol).

8. A process for preventing high-temperature coking of a bearing bush according to claim 5, characterized in that, The specific implementation process of the paint film index detection is as follows: D1. Install the filter membrane into the filter funnel, wet it with n-heptane and evacuate for 30 seconds to remove the residual solvent, and record the initial color of the filter membrane; D2. Measure 10 mL of the oil sample, add 40 mL of n-heptane, and stir until completely dissolved to obtain a mixed solution; D3. Pour the mixture into a filtering funnel, start the vacuum pump and slowly filter it until a uniform deposit forms on the surface of the membrane. Then rinse the inner wall of the funnel with 10 mL of n-heptane to ensure that polar substances are completely adsorbed on the membrane; D4. Turn off the vacuum pump, carefully remove the membrane, lay it flat on a dust-free filter paper, and then dry it at room temperature for 30 minutes to observe the color change of the membrane; D5. Measure the absorbance of the membrane at a wavelength of 465 nm using a spectrophotometer, and calculate the MPC value according to the standard curve.

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