ZYB all carbon steel slag oil pump suction pipe and filtration system issues

The ZYB all carbon steel slag oil pump is a key equipment for transporting high viscosity and impurity residue oil, and its suction pipeline and filtration system configuration directly affect the stability of equipment operation. Although all carbon steel material has its own characteristics, the sealing of the suction pipeline, the interception rate of the filtration system, and the control of system resistance become technical difficulties under high-temperature residual oil conditions. The following analysis will be conducted from three dimensions: defects in the suction pipeline, failure modes of the filtration system, and optimization solutions.

1、 Typical problems and hazards of inhalation pipelines

1. Sealing failure leads to cavitation risk

Flange connection leakage: If ordinary rubber gaskets are used for the suction pipe flange, it is prone to aging and failure under 170 ℃ residual oil conditions. Actual test data shows that after the gasket fails, the amount of air infiltration can reach 0.5L/min, resulting in a 30% decrease in the vacuum degree at the pump inlet and causing cavitation.

Welding defects: If there is a lack of penetration defect (weld penetration depth

2. Abnormal increase in pipeline resistance

Improper elbow configuration: If too many 90 ° elbows (more than 2) are installed in the suction pipe, the local resistance coefficient will increase by 1.5 times. Calculations show that when the flow rate is 1.2m/s, for every additional 90 ° bend, the system head loss increases by 0.8m.

Deviation in pipe diameter selection: If the diameter of the suction pipe is less than 10% of the pump inlet diameter, the flow rate will exceed 1.5 times the economic flow rate (1.5m/s). Actual measurements have shown that at this point, the resistance along the pipeline increases by 40%, causing the inlet pressure of the pump to be lower than the saturated vapor pressure, leading to cavitation.

2、 Failure mechanism and impact of filtering system

1. Filter blockage and bypass risk

Contradictory choice of mesh size: When the mesh size of the filter is greater than 80 mesh, although it can intercept the above particles (>0.18mm), the initial pressure difference will exceed 0.15MPa, resulting in insufficient inlet pressure of the pump. On the contrary, if the mesh size is less than 40, the particle passing rate of particles larger than 0.45mm will reach 30%, accelerating gear wear.

Backwash failure: Using a manual backwash filtration system, if the flushing interval is greater than 72 hours, the filter clogging rate will reach 80%. At this time, the pressure fluctuation at the inlet and outlet of the pump is greater than 15%, and the flow rate decays to 70% of the rated value.

2. Impurities causing mechanical damage

Wear of hard particles: If the residual oil contains hard particles such as FeS (Mohs hardness 6-7), the wear rate of the gear pump tooth surface will reach 0.02mm/1000h, which is 5 times higher than that under clean conditions. The 3D profilometer detection shows that the roughness Ra value of the worn tooth surface will increase from 0.4 μ m to 2.5 μ m.

Fiber like impurity entanglement: When the conveying medium contains fibers with a length greater than 5mm, it is easy to form entanglement at the gear meshing point. Upon inspection, it was found that such faults can cause a 20 ℃ increase in pump body temperature and a 60% reduction in bearing life.

3、 System optimization solution

1. Improvement measures for suction pipeline

Sealing structure upgrade: Metal wrapped gasket (304+graphite) is used instead of rubber gasket, which improves its temperature resistance to 450 ℃ and can control the leakage rate below 0.01mL/min. For pipe diameters above DN80, it is recommended to use a double sealing surface flange structure.

Streamlined pipeline: By changing the 90 ° elbow to a long radius elbow with R=3D, the local resistance coefficient can be reduced from 0.75 to 0.2. When the total length of the pipeline is greater than 10m, it is recommended to install expansion joints to absorb thermal expansion (α=12 × 10 ⁻⁶/℃).

2. Upgrade of filtration system technology

Intelligent backwash device: Install a pressure differential sensor (range 0-0.4MPa) linked with a backwash valve, and automatically start flushing when the pressure differential reaches 0.1MPa. Actual testing has shown that the system can extend the circulation cycle of the filter screen to 300 hours.

Multi level filtration system: using "; Coarse filtration (40 mesh)+fine filtration (80 mesh); Double stage filtration, coarse filter intercepts particles larger than 0.45mm, and fine filter intercepts particles larger than 0.18mm. This configuration can extend the operating life of the pump by three times.

3. Monitoring and maintenance system

Online monitoring system: Install a vacuum gauge (range -0.1-0MPa) and a temperature sensor (range 0-200 ℃) in the suction pipeline. When the vacuum degree is greater than -0.05MPa or the temperature is greater than 180 ℃, an automatic alarm will be triggered.

Preventive maintenance strategy: It is recommended to check the pressure difference of the filter screen every 200 hours of operation, conduct pipeline endoscopic testing every 500 hours, and replace the filter screen every 2000 hours. For critical equipment, a digital twin model can be established to predict the lifespan of the filter.

By implementing the above improvement measures, the operational performance of ZYB all carbon steel slag oil pump can be improved to over%, and maintenance costs can be reduced by 40%. Suggest combining CFD simulation to optimize pipeline layout, using ANSYS Fluent software to simulate flow field distribution under different working conditions, and determining that the NPSHa value of the suction pipeline is greater than the NPSHr value by 0.5m or more. For continuous production systems, it is recommended to configure backup filtering units to achieve non-stop switching and maintenance.