Overview
Basket filters, as the core filtering equipment in industrial pipeline systems, achieve highly efficient separation of solid impurities in fluids through high-precision filter screen interception. They are a crucial link in ensuring the safe operation of equipment and product quality in industries such as petrochemical, electric power, food, and medicine. The technological core lies in the use of high-strength metal filter screens (with an optional precision range of 5 - 5000μm). Utilizing the principle of mechanical screening, impurities such as rust, welding slag, and particles are intercepted in the filter basket without affecting the system flow, thus avoiding the wear and blockage of pumps, valves, instruments, and other equipment. Compared with traditional filtering methods, basket filters have advantages such as large dirt-holding capacity, convenient cleaning, and high resistance to high temperature and pressure. They can handle fluids with a viscosity as high as 10,000 cP and are widely used in the pretreatment and fine filtration of various industrial media.
Core Working Principle and Structural Design
I. Analysis of the Interception Mechanism
1. Mechanical Screening Process
After the fluid enters the filter from the inlet, it passes through the filter screen under pressure. Impurities larger than the pore size of the filter screen are retained in the filter basket, and the purified fluid flows out from the outlet. The filtering precision depends on the mesh number of the filter screen (for example, 100 mesh corresponds to 150μm), which can be flexibly selected according to process requirements.
2. Differential Pressure Control Logic
As impurities accumulate, the pressure difference between the inlet and outlet gradually increases. When the pressure difference reaches the set value (usually 0.05 - 0.1MPa), it indicates that the filter basket needs to be cleaned or replaced. Some models are equipped with a differential pressure gauge or an electric contact pressure gauge to achieve automated monitoring.
3. Filter Basket Structural Innovation
- Wedge Wire Filter Basket: It is made by winding stainless steel wires with a trapezoidal cross-section. The width of the gap is adjustable from 0.025 to 3mm, suitable for high-viscosity fluids and high-precision filtration.
- Multi-Layer Sintered Mesh: It is formed by sintering 5 - 7 layers of stainless steel meshes, with high strength and strong dirt-holding capacity, and can withstand a backwashing pressure of up to 0.8MPa.
- Punched Plate Support: The inner layer is equipped with a punched plate framework to enhance the anti-deformation ability of the filter basket, suitable for high-pressure systems (≤10MPa).
II. Structural Design Advantages
1. Fully Sealed Pressure-Bearing Design
The outer shell is made of 304/316L stainless steel or carbon steel materials. The flange connection complies with the ASME B16.5 standard, and the pressure resistance rating can reach PN16 - PN100, suitable for high temperature (-200°C to 450°C) and corrosive media (such as acid, alkali, and salt solutions).
2. Quick-Opening Design
Some models are equipped with quick-opening blind flanges (such as clamp type, bolt type). A single person can complete the replacement of the filter basket within 3 - 5 minutes, saving 70% of the maintenance time compared with the traditional flange connection.
3. Backwashing Function
An optional online backwashing device is available. By using reverse water flow (or gas) to impact the filter basket, impurities can be detached and discharged without disassembling the filter, which is suitable for continuously operating systems.
Analysis of Typical Application Scenarios
1. Protection of Petrochemical Pipelines
In the circulating oil system of the catalytic cracking unit of a certain refinery, the basket filter (with a filter screen precision of 40μm) intercepts catalyst dust and coke particles, reducing the wear rate of the pump by 85% and extending the maintenance cycle from 2 months to 1 year. The equipment is made of 316L stainless steel and can withstand a high temperature of 320°C and the corrosive environment of H₂S.
2. Aseptic Filtration in the Food and Beverage Industry
In the deoxygenated water system of the beer filling production line, the basket filter (with a precision of 10μm) cooperates with ultraviolet sterilization to intercept yeast and particulate impurities, ensuring that the turbidity of the water before filling is <0.1NTU. The filter basket is treated by electrolytic polishing and complies with the FDA hygiene standards, and can be sterilized by online steam (at 121°C for 30 minutes).
3. Fine Treatment of Condensate Water in the Power Industry
In the condensate water system of a thermal power plant, the basket filter (with a precision of 25μm) serves as a pre-filtration unit to intercept the corrosion products of the steam turbine and resin fragments, protecting the subsequent mixed bed ion exchanger. The equipment adopts a bypass design and can be switched and cleaned online to ensure the continuous operation of the unit.
4. Filtration of Purified Water in the Pharmaceutical Process
In the terminal filtration process of the purified water system in a pharmaceutical factory, the basket filter (with a precision of 5μm) removes activated carbon particles and microorganisms, ensuring that the endotoxin in the effluent water is <0.25EU/mL. The filter shell adopts a hygienic quick-installation interface, which is convenient for CIP/SIP cleaning and complies with the GMP certification requirements.
Technical Advantages and Industry Value
1. Efficient Interception and Long-Term Operation
- Large dirt-holding capacity: The effective volume of the filter basket reaches 10 - 50L, and the single cleaning cycle can be extended to 1 - 3 months, reducing the number of shutdowns for maintenance.
- Stable flow: The special flow channel design makes the pressure loss <0.02MPa, which is 50% lower than that of the Y-type filter with the same specification, ensuring the optimization of system energy consumption.
2. Convenient Maintenance and Cost Control
- Replaceable filter basket: The modular design supports the rapid replacement of filter baskets with different precisions to meet the needs of process adjustments.
- Low life cycle cost: The stainless steel filter basket can be repeatedly cleaned and used (>100 times), saving 80% of the consumable cost compared with disposable cartridges.
3. Safety and Reliability and Process Adaptability
- Explosion-proof certification: Optional explosion-proof designs with ATEX/IECEx certifications are available, suitable for flammable and explosive working conditions.
- Multiphase flow treatment: The special structural design can handle gas-liquid-solid three-phase flow simultaneously, with a separation efficiency of >99%.
Selection and Maintenance Guidelines
I. Key Selection Factors
- Filtering Precision Matching:
For general pump protection, choose 50 - 100μm. For instrument protection, choose 10 - 50μm. For process fine filtration, choose 5 - 25μm.
- Material Compatibility:
For corrosive media, choose 316L or Hastelloy alloys. For high-temperature and high-pressure applications, choose carbon steel with an inner coating (such as Teflon).
- Flow and Pressure Calculation:
Select the diameter according to 1.5 times the maximum flow to ensure that the filtering area is 3 - 5 times the cross-sectional area of the pipeline, reducing the pressure loss.
II. Maintenance Optimization Strategies
1. Daily Inspection
- Record the pressure difference between the inlet and outlet every week. When the pressure difference exceeds 0.1MPa, clean the filter basket in a timely manner.
- Check whether the sealing surface leaks. For high-temperature systems, it is necessary to regularly tighten the bolts (it is recommended to do it once a month).
2. Filter Basket Cleaning Process
- For mechanical impurities: Use 0.5MPa compressed air for blowing or ultrasonic cleaning.
- For viscous pollutants: Soak in a 5% sodium hydroxide solution (at 60°C) for 2 hours and then rinse with clean water.
- For microbial contamination: Soak in a 0.1% sodium hypochlorite solution for disinfection, rinse and then dry for standby.
3. Troubleshooting
- Abnormally increased pressure difference: Check whether there is filter basket blockage or unreasonable flow channel design.
- Decreased flow: Confirm whether the effective filtering area is reduced due to impurity accumulation. If necessary, add a standby filter.
