What factors cause wax deposition in gear oil pump pipelines?

The support of the gear oil pump adopts a double end ball bearing structure, with lubricating oil lubrication at the front end and grease lubrication at the rear end. There is a guide oil pipe in the middle to observe the sealing condition and recover the heat transfer oil at any time. Sedimentation refers to the process of sedimentation and accumulation of materials transported by a moving medium due to changes in conditions when they reach a suitable location. The combination of packing seal and mechanical seal is adopted. The packing used for packing seal has thermal adaptability, while the mechanical seal uses mechanical and good hard alloy materials to achieve sealing performance under high temperature conditions. Broadly speaking, it refers to the process of accumulating and forming rocks from sedimentary materials, while narrowly speaking, it refers to the mechanical precipitation of suspended substances in media such as water. So what are the factors causing wax deposition in gear oil pump pipelines?

1. Pipeline pressure

When the pipeline pressure is lower than the saturation pressure of crude oil, gas-phase substances in the crude oil will dissociate from it, which not only reduces the content of light components in the crude oil, but also takes away some of the heat in the crude oil, resulting in an increase in wax deposition after the dual factors.

2. Composition and properties of crude oil in pipelines

The heavy components contained in crude oil have a direct impact on the wax deposition effect. The more heavy components there are, the less soluble the wax in the crude oil is, and the more severe the tendency for wax deposition. But the gum and asphaltene contained in crude oil have an impact on wax deposition in pipelines. Colloidal substances refer to compounds with high molecular weight in crude oil, belonging to a type of surface active substance. They are dispersed in a semi-solid state in crude oil and can adsorb on the surface of wax at the beginning of crystallization, playing a role in isolation and preventing wax crystals from continuing to grow. Asphalt is a type of polymer that is dispersed in small particles in crude oil and can act as a dispersant for wax crystals. As the content of resin increases, the temperature of wax precipitation decreases, and the wax crystals are evenly dispersed and tightly bound to the resin. However, in the presence of gum and asphaltene, wax deposits on the pipe wall and is not easily washed away by the oil flow. In summary, to a certain extent, the presence of gum and asphaltene can both alleviate wax deposition and increase the bonding strength of wax, thereby reducing wax deposition.

3. Mechanical impurities and water components in crude oil

The mechanical impurities and rough surface in crude oil are conducive to the adhesion and crystallization of wax molecules. The more mechanical impurities contained in crude oil, the easier it is for wax deposition to occur during pipeline transportation.

4. Pipe wall roughness and surface material

The wax deposition in the gear oil pump pipeline is affected by the pipeline material: the rougher the inner wall of the pipeline, the easier it is for the crude oil to hang on the inner wall of the pipeline during transportation, making it more prone to wax deposition. On the contrary, the smoother the pipe wall, the smoother the flow of crude oil, and the less likely it is to wax deposition. In addition, for the material of the inner wall of the pipeline, lipophilic materials are more prone to wax formation than hydrophilic materials.

5. The running time of the pipeline

As the running time of the pipeline increases, the conveying distance increases, and the thickness of the wax layer becomes thicker. When a certain time is reached, the degree of thickening gradually decreases. This is because the thickness of the wax layer increases, leading to an increase in thermal resistance, a decrease in the heat transfer coefficient between the oil temperature and the pipe wall, a decrease in temperature difference, and a gradual decrease in wax deposition increment.

6. Flow velocity of fluid in pipeline

The faster the oil flow velocity in the gear oil pump pipeline, the greater the shear stress on the pipe wall, and the stronger the flushing effect of the oil flow on the pipe wall. The lower the wax deposition rate, the less likely the wax in the crude oil is to deposit, and the thickness of wax deposition on the pipe wall becomes thinner.

7. The ambient temperature of the fluid inside the pipeline

Wax deposition is greatly affected by temperature. When the temperature is low, the fluidity of high wax crude oil decreases, the movement of wax molecules slows down, and it is easy to crystallize and precipitate. Therefore, when the temperature of crude oil is low, it is prone to wax formation. In addition, due to the temperature difference between the crude oil temperature and the pipe wall temperature, wax will crystallize on the surface of the pipe wall, which is also the main factor leading to wax deposition in pipelines.