Lubricating grease for maintenance-free bearing of pumping unit

Abstract

The application belongs to the technical field of oil field lubrication, and particularly relates to a lubricating grease for maintenance-free bearing of pumping unit. The lubricating grease for maintenance-free bearing of pumping unit has better structural stability, outstanding anti-wear property and smaller dynamic leakage, so that the lubricating requirement of the maintenance-free bearing of pumping unit can be fully met. The lubricating grease for maintenance-free bearing of pumping unit specifically comprises the following components: base oil, thickening agent, crystallization complex agent, co-crystallization complex agent, crosslinking agent, fiber structure stabilizer, antioxidant, anti-wear agent, friction modifier, anti-rust agent and viscosity index improver.

Description

Technical Field

[0001] This invention belongs to the field of oilfield lubrication technology, and in particular relates to a grease for maintenance-free bearings of oil pumping units. Background Technology

[0002] Currently, Shengli Oilfield has over 21,000 pumping units in operation, of which more than 15,000 are beam pumping units. It is worth noting that beam pumping units operate continuously outdoors year-round, under harsh conditions with large temperature variations. They are also affected by dust, rain, and saline-alkali moisture, requiring regular lubrication of the unit's conventional bearings (bearing assemblies specifically include support shaft bearings, tail shaft bearings, and crank pin bearings).

[0003] However, further research revealed that the pumping unit bearings are installed at a height exceeding 2 meters, requiring operators to use specialized climbing equipment for work, which poses high safety risks and is physically demanding. Furthermore, commonly used ordinary greases are prone to leakage during use, leading to rust, reduced friction reduction, oxidation failure, and other problems, resulting in unsatisfactory performance.

[0004] Therefore, in order to meet the needs of actual working conditions, achieve safe and long-term continuous operation of oilfield pumping units, reduce the impact of unplanned shutdowns on crude oil production, reduce maintenance costs, and reduce the risks to personnel, equipment safety, and environmental pollution, it is urgent for those skilled in the art to develop a grease composition for maintenance-free bearings of pumping units, thereby meeting the industrial application requirements of maintenance-free bearings for pumping units. Summary of the Invention

[0005] This invention provides a grease for maintenance-free bearings of oil pumping units. By selecting appropriate components, the grease prepared has better structural stability, outstanding anti-wear properties, and less dynamic leakage, thereby fully meeting the lubrication requirements of maintenance-free bearings of oil pumping units.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A grease for maintenance-free bearings of oil pumping units, comprising the following components in percentage:

[0008] Base oil balance;

[0009] Thickener 8-18%;

[0010] Crystallizing compound agent 2-6%;

[0011] Co-crystallization compound agent 1-3%;

[0012] Crosslinking agent 0.5-1.5;

[0013] Fiber structure stabilizer 1.8-4.3%;

[0014] Antioxidant 0.5-2%;

[0015] Anti-wear agent 4-8%;

[0016] Friction modifier 2-4%;

[0017] Rust inhibitor 1.2-2.6%;

[0018] Viscosity index improver 3-6%.

[0019] More preferably, the base oil is a bright oil with the grade 150BS.

[0020] More preferably, the thickener is a saponification reaction product of 12-hydroxystearic acid and lithium hydroxide monohydrate; wherein the mass ratio of 12-hydroxystearic acid to lithium hydroxide monohydrate is 84%:16%.

[0021] More preferably, the crystallizing composite agent is a reactant of sebacic acid and calcium hydroxide; wherein the mass ratio of sebacic acid to calcium hydroxide is 73%:27%.

[0022] More preferably, the co-crystallization composite agent is a composite of lithium metaborate and calcium salicylate; wherein the mass ratio of lithium metaborate to calcium salicylate is 88%:12%.

[0023] More preferably, the crosslinking agent is a complex of calcium stearate and calcium naphthenate; wherein the mass ratio of calcium stearate to calcium naphthenate is 60%:40%.

[0024] More preferably, the fiber structure stabilizer is a complex of glycerol and castor oil; wherein the mass ratio of glycerol to castor oil is 70%:30%.

[0025] More preferably, the antioxidant is a complex of diphenylamine, 2,6-di-tert-butyl-p-cresol, calcium alkyl salicylate T109, and diisooctyl diphenylamine; wherein the mass ratio of diphenylamine: 2,6-di-tert-butyl-p-cresol: calcium alkyl salicylate T109: diisooctyl diphenylamine is 30%: 10%: 10%: 50%.

[0026] More preferably, the viscosity index improver is isopropyl copolymer OCP-A.

[0027] More preferably, the friction modifier is a composite of ethylene glycol oleate and sulfurized olefin cottonseed oil T405; wherein the mass ratio of ethylene glycol oleate to sulfurized olefin cottonseed oil T405 is 20%:80%;

[0028] The rust inhibitor is a complex of benzotriazole T706, zinc naphthenate T704, and alkenyl succinic acid; wherein the mass ratio of benzotriazole T706: zinc naphthenate T704: alkenyl succinic acid is 30%:30%:40%.

[0029] This invention provides a grease for maintenance-free bearings in oil pumping units. The grease comprises the following components: base oil, thickener, crystallizing compound agent, co-crystallizing compound agent, crosslinking agent, fiber structure stabilizer, antioxidant, anti-wear agent, friction modifier, rust inhibitor, and viscosity index improver. The grease for maintenance-free bearings in oil pumping units, possessing the above-mentioned component characteristics, has at least the following features:

[0030] It can maintain good fiber structure stability even under strong high-frequency shearing conditions inside the bearing. Under high speed load conditions, the wear amount is small in the wear test, and the wear resistance is outstanding. Under strong mechanical motion and extrusion conditions, such as periodic vibration, the dynamic leakage is small, and the mechanical performance is excellent. In the enhanced life test, the bearing running time is long at high ambient temperature, and the enhanced life of the grease is outstanding. Detailed Implementation

[0031] This invention provides a grease for maintenance-free bearings of oil pumping units. By selecting appropriate components, the grease prepared has better structural stability, outstanding anti-wear properties, and less dynamic leakage, thereby fully meeting the lubrication requirements of maintenance-free bearings of oil pumping units.

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] Example 1

[0034] This invention provides a grease for maintenance-free bearings of oil pumping units. Specifically, this grease for maintenance-free bearings of oil pumping units comprises the following components, defined by percentage content:

[0035] Base oil balance;

[0036] Thickener 8-18%;

[0037] Crystallizing compound agent 2-6%;

[0038] Co-crystallization compound agent 1-3%;

[0039] Crosslinking agent 0.5-1.5;

[0040] Fiber structure stabilizer 1.8-4.3%;

[0041] Antioxidant 0.5-2%;

[0042] Anti-wear agent 4-8%;

[0043] Friction modifier 2-4%;

[0044] Rust inhibitor 1.2-2.6%;

[0045] Viscosity index improver 3-6%.

[0046] In a preferred embodiment of the present invention, the base oil used is a bright oil with the grade 150BS.

[0047] The thickener is a saponification product of 12-hydroxystearic acid and lithium hydroxide monohydrate; wherein the mass ratio of 12-hydroxystearic acid to lithium hydroxide monohydrate is 84%:16%.

[0048] The crystallizing composite agent is a reactant of sebacic acid and calcium hydroxide; wherein the mass ratio of sebacic acid to calcium hydroxide is 73%:27%.

[0049] The co-crystallization composite agent is a complex of lithium metaborate and calcium salicylate; wherein the mass ratio of lithium metaborate to calcium salicylate is 88%:12%.

[0050] The crosslinking agent is a complex of calcium stearate and calcium naphthenate; wherein the mass ratio of calcium stearate to calcium naphthenate is 60%:40%.

[0051] The fiber structure stabilizer is a complex of glycerol and castor oil; wherein the mass ratio of glycerol to castor oil is 70%:30%.

[0052] The antioxidant is a complex of diphenylamine, 2,6-di-tert-butyl-p-cresol, calcium alkyl salicylate T109, and diisooctyl diphenylamine; wherein the mass ratio of diphenylamine: 2,6-di-tert-butyl-p-cresol: calcium alkyl salicylate T109: diisooctyl diphenylamine is 30%: 10%: 10%: 50%.

[0053] The viscosity index improver used isopropylene copolymer OCP-A.

[0054] The friction modifier is a complex of ethylene glycol oleate and sulfurized olefin cottonseed oil T405; wherein the mass ratio of ethylene glycol oleate to sulfurized olefin cottonseed oil T405 is 20%:80%.

[0055] The rust inhibitor is a complex of benzotriazole T706, zinc naphthenate T704, and alkenyl succinic acid; wherein the mass ratio of benzotriazole T706: zinc naphthenate T704: alkenyl succinic acid is 30%:30%:40%.

[0056] In addition, the anti-wear agent can be a complex of zinc dialkyl dithiophosphate, high-alkalinity petroleum sulfonate, and medium-load vehicle gear oil compound; wherein, the mass ratio of zinc dialkyl dithiophosphate: high-alkalinity petroleum sulfonate: medium-load vehicle gear oil compound is 70%:20%:10%.

[0057] Example 2

[0058] Based on Example 1, Example 2 further provides specific component data for a set of greases used in maintenance-free bearings of oil pumping units. Specific data can be found in the table below:

[0059] Components mass percentage 150BS of gloss varnish 76 The saponification reaction product consists of 84% 12-hydroxystearic acid and 16% lithium hydroxide monohydrate by mass ratio. 8 The reactants consist of 73% sebacic acid and 27% calcium hydroxide by mass. 2 A complex of lithium metaborate (88%) and calcium salicylate (12%) by mass. 1 A compound of 60% calcium stearate and 40% calcium naphthenate by mass. 0.5 A compound containing 70% glycerol and 30% castor oil by mass. 1.8 A compound containing 30% diphenylamine, 10% 2,6-di-tert-butyl-p-cresol, 10% alkyl salicylate calcium T109, and 50% diisooctyl diphenylamine by mass ratio. 0.5 The compound consists of 70% zinc dialkyl dithiophosphate, 20% high-base-value calcium petroleum sulfonate, and 10% medium-load vehicle gear oil compound T4143 (by mass ratio). 4 A compound of 20% ethylene glycol oleate and 80% sulfurized olefin cottonseed oil T405 by mass ratio. 2 A composite of 30% benzotriazole T706, 30% zinc naphthenate T704, and 40% alkenyl succinic acid by mass ratio. 1.2 Viscosity index improver is isopropyl copolymer 3

[0060] Example 3

[0061] Based on Example 1, Example 3 further provides specific component data for a set of greases used in maintenance-free bearings of oil pumping units. Specific data can be found in the table below:

[0062] Components mass percentage 150BS of gloss varnish 65.1 The saponification reaction product consists of 84% 12-hydroxystearic acid and 16% lithium hydroxide monohydrate by mass ratio. 12 The reactants consist of 73% sebacic acid and 27% calcium hydroxide by mass. 3.5 A complex of lithium metaborate (88%) and calcium salicylate (12%) by mass. 1.6 A compound of 60% calcium stearate and 40% calcium naphthenate by mass. 0.9 A compound containing 70% glycerol and 30% castor oil by mass. 2.5 A compound containing 30% diphenylamine, 10% 2,6-di-tert-butyl-p-cresol, 10% alkyl salicylate calcium T109, and 50% diisooctyl diphenylamine by mass ratio. 1 The compound consists of 70% zinc dialkyl dithiophosphate, 20% high-base-value calcium petroleum sulfonate, and 10% medium-load vehicle gear oil compound T4143 (by mass ratio). 5 A compound of 20% ethylene glycol oleate and 80% sulfurized olefin cottonseed oil T405 by mass ratio. 2.8 A composite of 30% benzotriazole T706, 30% zinc naphthenate T704, and 40% alkenyl succinic acid by mass ratio. 1.6 Viscosity index improver is isopropyl copolymer 4

[0063] Example 4

[0064] Based on Example 1, Example 4 further provides specific component data for a set of greases used in maintenance-free bearings of oil pumping units. Specific data can be found in the table below:

[0065] Components mass percentage 150BS of gloss varnish 55.8 The saponification reaction product consists of 84% 12-hydroxystearic acid and 16% lithium hydroxide monohydrate by mass ratio. 15 The reactants consist of 73% sebacic acid and 27% calcium hydroxide by mass. 4 A complex of lithium metaborate (88%) and calcium salicylate (12%) by mass. 2.2 A compound of 60% calcium stearate and 40% calcium naphthenate by mass. 1.2 A compound containing 70% glycerol and 30% castor oil by mass. 3.2 A compound containing 30% diphenylamine, 10% 2,6-di-tert-butyl-p-cresol, 10% alkyl salicylate calcium T109, and 50% diisooctyl diphenylamine by mass ratio. 1.5 The compound consists of 70% zinc dialkyl dithiophosphate, 20% high-base-value calcium petroleum sulfonate, and 10% medium-load vehicle gear oil compound T4143 (by mass ratio). 6.5 A compound of 20% ethylene glycol oleate and 80% sulfurized olefin cottonseed oil T405 by mass ratio. 3.5 A composite of 30% benzotriazole T706, 30% zinc naphthenate T704, and 40% alkenyl succinic acid by mass ratio. 2.1 Viscosity index improver is isopropyl copolymer 5

[0066] Example 5

[0067] Based on Example 1, Example 5 further provides specific component data for a set of greases used in maintenance-free bearings of oil pumping units. Specific data can be found in the table below:

[0068] Components mass percentage 150BS of gloss varnish 44.6 The saponification reaction product consists of 84% 12-hydroxystearic acid and 16% lithium hydroxide monohydrate by mass ratio. 18 The reactants consist of 73% sebacic acid and 27% calcium hydroxide by mass. 6 A complex of lithium metaborate (88%) and calcium salicylate (12%) by mass. 3 A compound of 60% calcium stearate and 40% calcium naphthenate by mass. 1.5 A compound containing 70% glycerol and 30% castor oil by mass. 4.3 A compound containing 30% diphenylamine, 10% 2,6-di-tert-butyl-p-cresol, 10% alkyl salicylate calcium T109, and 50% diisooctyl diphenylamine by mass ratio. 2 The compound consists of 70% zinc dialkyl dithiophosphate, 20% high-base-value calcium petroleum sulfonate, and 10% medium-load vehicle gear oil compound T4143 (by mass ratio). 8 A compound of 20% ethylene glycol oleate and 80% sulfurized olefin cottonseed oil T405 by mass ratio. 4 A composite of 30% benzotriazole T706, 30% zinc naphthenate T704, and 40% alkenyl succinic acid by mass ratio. 2.6 Viscosity index improver is isopropyl copolymer 6

[0069] Example 6

[0070] Based on Example 1, and combined with the specific component data provided in Examples 2-5, the lubricating greases for maintenance-free bearings of oil pumping units prepared in each example were experimentally verified, and their lubrication performance was quantitatively analyzed as follows, which can be specifically described as follows:

[0071] First, comparative examples were set up (the following comparative examples use three high-performance grease products currently used in oil pumping units). Among them, Comparative Example 1 used general-purpose lithium-based grease No. 2; Comparative Example 2 used extreme pressure complex lithium-based grease; and Comparative Example 3 used complex calcium sulfonate-based grease No. 2.

[0072] Then, comparative experiments were conducted on the greases for maintenance-free bearings of oil pumping units corresponding to the components described in Comparative Examples 1-3 and Examples 2-5 under the same operating conditions. Their performance characteristics are as follows:

[0073] Experimental Project Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Experimental methods Working cone penetration 293 286 270 266 285 283 279 GB / T 269 100,000 shear changes 23 28 30 30 25 32 37 GB / T 269 Drip 274 289 269 288 198 283 330 GB / T3498 Evaporation loss (99℃, 22h) 0.20 0.22 0.26 0.25 0.28 0.32 0.3 GB / T7325 Oil separation on steel mesh (100℃, 24h) 3.2 2.7 2.6 2.3 3.5 4.1 4.3 SH / T0324 Corrosion resistance (52℃, 48h) qualified qualified qualified qualified qualified qualified qualified GB / T5018 Difference between working cone penetration and actual penetration after 1 million shear tests 47 39 55 42 135 119 185 GB / T 269 FE8 Wear Test: 20KN, 750 rpm, 25℃, 500h; Wear Amount (mg) 13 15 11 9 49 43 57 DIN51819 V2F leakage test 1000 rpm 72 h g 24 15 8 14 115 94 88 SKF Standard Method High-temperature life running-in test 160℃ h 185 220 200 290 40 60 80 ASTM D3527

[0074] Based on experimental data and comparative analysis, it can be found that the lubricating grease for maintenance-free bearings of oil pumping units provided by this invention has the following performance characteristics:

[0075] 1. The difference between the 1 million shear cycles and the working cone penetration reflects the quality of the grease's mechanical stability after being subjected to enhanced shearing. The magnitude of the change reflects the quality of the grease's structure; the smaller the change, the better the structural stability, the longer the mechanical life of the grease, and the more suitable it is for long-term operating conditions. If the consistency of the grease changes significantly after shearing, not only will its lifespan not be guaranteed, but it may also leak during use, greatly reducing the grease's lifespan.

[0076] The greases for maintenance-free pumping unit bearings corresponding to Examples 2-5 all showed a difference of less than 60 in the 1 million shear tests and working cone penetration values, while the greases for Comparative Examples 1-3 all showed a difference greater than 110. This indicates that the greases for maintenance-free pumping unit bearings provided by this invention exhibit stable mechanical structure and longer physical life after undergoing mechanical shear conditions. This reflects the good fiber structure stability maintained by the greases for maintenance-free pumping unit bearings under intense, high-frequency shear conditions after being installed in the bearing.

[0077] 2. FE8 Wear Test: This test examines the wear of various friction components after the lubricating grease is filled into a specified bearing and operates for 500 hours under specified ambient temperature, load, and speed conditions. Here, we selected a tapered roller bearing, filled with grease, and operated for 500 hours under the following conditions: 20KN load, 750 rpm, ambient temperature 25℃. After the running-in test, the bearing was disassembled, and the difference in wear between the inner and outer rings and the cage rollers before and after the test was calculated as the wear amount. The smaller the value, the better the wear resistance.

[0078] The wear amount tested in Examples 2-5 for the maintenance-free bearing grease used in oil pumping units was less than 16 mg, while the wear amount tested in Comparative Examples 1-3 was greater than 40 mg. This indicates that the maintenance-free bearing grease for oil pumping units provided by this invention has good anti-wear performance.

[0079] 3. V2F Leakage Test: Under simulated impact and vibration conditions, the mechanical stability of the grease is measured by testing the amount of grease leakage. Specifically, a speed of 1000 RPM is selected, and the test lasts for 72 hours. The amount of grease leakage from the bearing is statistically analyzed; the smaller the leakage, the better the grease adhesion and the better the mechanical performance.

[0080] The test results for the grease used in the maintenance-free bearings of the oil pumping unit corresponding to Examples 2-5 were all less than 25g, while the test results for Comparative Examples 1-3 were all greater than 85g. This indicates that the grease for the maintenance-free bearings of the oil pumping unit provided by this invention has excellent mechanical properties, exhibiting low dynamic leakage under strong mechanical motion and extrusion conditions, such as cyclic vibration.

[0081] 4. High-Temperature Life Running-in Test: Using an ASTM D3527 testing machine, after the grease is filled into the bearing, the axial load of the bearing is 111N, and the bearing is run-in at a speed of 1000 rpm at an ambient temperature of 160℃. The life of the drive motor ends when the grease deteriorates and ages and exceeds the set disconnection value. The running-in time is the enhanced test life of the grease, and the larger the value, the longer the life.

[0082] The test results of the grease for the maintenance-free bearings of the oil pumping unit corresponding to Examples 2-5 are all greater than 180 hours, while the test results of Comparative Examples 1-3 are less than 85 hours. This indicates that the grease for the maintenance-free bearings of the oil pumping unit provided by the present invention has a long bearing running time at higher ambient temperatures and outstanding enhanced lifespan.

[0083] This invention provides a grease for maintenance-free bearings in oil pumping units. The grease comprises the following components: base oil, thickener, crystallizing compound agent, co-crystallizing compound agent, crosslinking agent, fiber structure stabilizer, antioxidant, anti-wear agent, friction modifier, rust inhibitor, and viscosity index improver. The grease for maintenance-free bearings in oil pumping units, possessing the above-mentioned component characteristics, has at least the following features:

[0084] It can maintain good fiber structure stability even under strong high-frequency shearing conditions inside the bearing. Under high speed load conditions, the wear amount is small in the wear test, and the wear resistance is outstanding. Under strong mechanical motion and extrusion conditions, such as periodic vibration, the dynamic leakage is small, and the mechanical performance is excellent. In the enhanced life test, the bearing running time is long at high ambient temperature, and the enhanced life of the grease is outstanding.

[0085] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A lubricating grease for a maintenance-free bearing of a pumping unit, characterized by, It comprises the following components determined by mass percentage: Base oil balance; Thickening agent 8-18%; Crystallization complexing agent 2-6%; Co-crystallization complexing agent 1-3%; Crosslinking agent 0.5-1.5; Fiber structure stabilizer 1.8-4.3%; Antioxidant 0.5-2%; Anti-wear agent 4-8%; Friction modifier 2-4%; Rust inhibitor 1.2-2.6%; Viscosity index improver 3-6%; The fiber structure stabilizer uses a complex of glycerol and castor oil; wherein the mass ratio of glycerol: castor oil is 70%: 30%; The antioxidant uses a complex of diphenylamine, 2, 6-di-tert-butyl-p-cresol, calcium alkyl salicylate T109, and diisooctyl diphenylamine; wherein the mass ratio of diphenylamine: 2, 6-di-tert-butyl-p-cresol: calcium alkyl salicylate T109: diisooctyl diphenylamine is 30%: 10%: 10%: 50%; The crystallization complexing agent uses a reaction product of sebacic acid and calcium hydroxide; wherein the mass ratio of sebacic acid: calcium hydroxide is 73%: 27%; The co-crystallization complexing agent uses a complex of lithium metaborate and calcium salicylate; wherein the mass ratio of lithium metaborate: calcium salicylate is 88%: 12%; The crosslinking agent uses a complex of calcium stearate and calcium naphthenate; wherein the mass ratio of calcium stearate: calcium naphthenate is 60%: 40%.

2. The lubricating grease for a maintenance-free bearing of a pumping unit according to claim 1, characterized by The base oil uses bright stock with a grade of 150BS.

3. The lubricating grease for a maintenance-free bearing of a pumping unit according to claim 1, characterized by The thickening agent uses a saponification reaction product of 12-hydroxystearic acid and lithium hydroxide monohydrate; wherein the mass ratio of 12-hydroxystearic acid: lithium hydroxide monohydrate is 84%: 16%.

4. The lubricating grease for a maintenance-free bearing of a pumping unit according to claim 1, characterized by The viscosity index improver uses ethylene-propylene copolymer OCP-A.

5. The lubricating grease for a maintenance-free bearing of a pumping unit according to claim 1, characterized by The friction modifier uses a complex of ethylene glycol oleate and vulcanized olefin cottonseed oil T405; wherein the mass ratio of ethylene glycol oleate: vulcanized olefin cottonseed oil T405 is 20%: 80%; The rust inhibitor uses a complex of benzotriazole T706, zinc naphthenate T704, and alkenyl succinic acid; wherein the mass ratio of benzotriazole T706: zinc naphthenate T704: alkenyl succinic acid is 30%: 30%: 40%.