Анализ структуры и принципа фильтрации раневых фильтрующих патронов

Types of Filter Cartridges

When it comes to liquid filtration, there are many types of filter cartridges available. They can generally be categorized into two main types: surface filtration cartridges and depth filtration cartridges.

1. Surface Filtration Cartridges

Surface filtration cartridges capture contaminants on their outer surface. Once the filter surface becomes clogged with particles, it can no longer function effectively, which means these types of filters often have a shorter lifespan. While surface filters can sometimes be rinsed with water or compressed air for reuse, this method is not always effective. During backwashing, the cleaning fluid primarily passes through the path of least resistance, which can lead to blockages in other areas, making the filtration even less effective.

To clean these filters thoroughly, ultrasonic cleaning with pure water is the best method, although it can be costly. Alternatively, if the contaminants are acid-soluble, a mild acid can be used for cleaning. However, this method carries the risk of corroding and enlarging the filter pores, so the cleaned filter should be rinsed with pure water and tested for proper functionality before reuse. Common materials for surface filtration cartridges include sintered PVC filter rods, melt-blown polypropylene elements, and pure pulp filter paper.

2. Depth Filtration Cartridges

Depth filtration cartridges are designed to hold more contaminants and extend the time between cleanings, as the impurities are trapped within the filter matrix based on particle size. This type of filter typically lasts longer and maintains its filtration precision better than surface filters.

Wound filters, primarily made from all-polypropylene materials, are often referred to as “cotton cores.” Their advantages include achieving a high flow rate with low differential pressure, high filtration precision, and a long lifespan while effectively maintaining the filtration accuracy throughout the process.

Structure Characteristics of Wound Filter Cartridges

Wound filter cartridges are constructed by winding specialized coarse yarn around a porous core, creating multiple layers to achieve the desired diameter. As the coarse yarn spirals around the core, it forms thousands of diamond-shaped openings in the filter layer. The openings are tighter near the core and gradually increase in size towards the outer layers, allowing the larger openings to channel the liquid while providing effective filtration.

The design creates a convoluted flow path for the liquid, which extends the distance the liquid must travel through the filter, improving the filtration efficiency. The internal dimensions of the smallest diamond openings play a crucial role in determining the filter’s precision – smaller openings yield higher precision filters. Filter manufacturers typically provide a comparison chart relating filter precision to diamond hole sizes. Generally, an 8-channel design correlates to a precision of 100 microns, while a 15-channel design is 20 microns, and a 19-channel design can achieve 10 microns.

Filtration Characteristics of Wound Filter Cartridges

Wound filter cartridges are known for their ability to handle large flow rates. Each type of filter corresponds to a fixed number of channels (D), and the number of channels can be adjusted based on the length of the filter (L).

The total number of channels can be calculated using the formula:
Total channels = D × L × 2.

For example, consider a 250 mm long filter with a filtration precision of 20 microns, featuring 15 channels across its diameter and 51 channels along its length. This results in a total of 15 × 51 × 2 = 1,530 channels. If the filtration speed is 0.5 m³/h (approximately 8.3 L/min), the liquid disperses into 1,530 independent channels, reducing the flow rate to about 5.4 mL/min per channel.

In the case of a filter with a 3-micron precision, the number of channels increases to 27 in diameter and 91 in length, resulting in a total of 27 × 91 × 2 = 4,914 channels. While the filter media becomes denser, allowing for improved filtration, the increased number of channels means that the flow rate per channel drops to around 1.7 mL/min. Here, the term “siphon flow rate” can be applied due to the smooth distribution throughout the channels.

This structure allows wound filters to maintain excellent filtration performance at low pressure differentials, making them effective at removing colloidal or gelatinous substances from the liquid. Moreover, they can effectively filter out much smaller particles, which is why they are widely regarded as precision filtration components.

Selecting Wound Filter Cartridges

Given the competitive market, many manufacturers are attempting to cut costs, which can lead to negative impacts on filter quality. Common shortcuts include:

1. Simplified Winding Techniques: While this increases production efficiency, it can result in numerous blind holes (blocked filter openings), effectively degrading the filter to a surface filter type.

2. Altered Diameter and Thickness Standards: Reducing the thickness of the filter cartridge may seem like a cost-saving measure, but it can lead to a thinner filtration layer, shorter flow paths, and poorer filtration performance.

3. Use of Inferior Materials: Though cheaper materials might lower costs, they can lead to chemical corrosion of the filter, diminishing its effectiveness.

When choosing a wound filter supplier, consider the following:

– Check for Open Pores: If a significant number of pores are clogged (creating blind holes), the filter no longer serves its intended purpose.

– Inspect Dimensions: Ensure the inner and outer diameters meet industry standards and that the filter media has not been compromised.

– Corrosion Issues: After use, check for any signs of corrosion on the filter’s yarn and core. Corrosion not only weakens filtration efficacy but can also contaminate the filtered solution.

Applications of Wound Filter Cartridges

Due to their high flow rate, low pressure differential, compatibility with low-viscosity fluids, and excellent corrosion resistance, wound filter cartridges find widespread use in various industries. They are commonly utilized in:

– Pre-filtration for Large Water Systems: Ideal for pure water systems in industrial settings.
– Water Treatment: Processing water and wastewater in power plants and steel mills.
– Food Industry: Filtering edible oils, vegetable oils, syrups, and chocolate mixtures.
– Chemical Production: Filtering plating solutions, paints, fuels, cutting oils, heavy grease, and high-viscosity resins or oils.
– Pharmaceutical Filtration: They are highly effective for various filtration applications in the pharmaceutical industry.

The unique structure of wound filter cartridges allows them to handle higher pressures without compromising stability or lifespan. The use of non-toxic polypropylene fibers with hot-melt processing means that these filters are particularly well-suited for the food and beverage industry.

From mineral water to syrups, alcoholic beverages to edible oils, and various liquids in the electronics and pharmaceutical sectors, wound filter cartridges are essential for efficient liquid filtration. They effectively remove suspended solids and particles, allowing for high flow rates with minimal pressure loss while maintaining a longer lifespan and higher dirt-holding capacity. Various materials can be chosen based on the properties of the liquid being filtered, ensuring compatibility for optimal filtration results.

Filtration Principle of Wound Filter Cartridges

The filtration process using wound filter cartridges relies not only on the physical straining effect of the overlapping fibers creating a grid of openings but also involves the following key principles:

1. Fiber Hooking Action

As the liquid flows from the outer layer into the inner core of the cartridge through a narrow and winding passage, the crimped fibers on the channel walls capture and hold back the particles suspended in the liquid.

2. Particle Deposition

The narrow twisting paths cause the liquid to collide repeatedly with the channel walls, leading to the gradual settling of particles, akin to how sediment collects in the bends of a river.

3. Overall Filtration Mechanism

The liquid enters the filter through the inlet, passing from the outside in and becoming purified in the process. Impurities are retained within the depth and surface of the filter, allowing for effective filtration.

The liquid flows into the lower part of the filter housing, then from the outside towards the inside through the filter cartridge. Larger particles initially settle at the bottom and can be removed through a drain valve, while smaller particles are retained by the filter. Finally, the clean liquid, collected on the filter’s support plate, exits through the outlet pipe. The liquid then goes through the filtering, breaking up emulsified substances, enlarging water molecules, and causing coagulation, with remaining impurities trapped in the filter, and the coalesced water droplets settling in the sediment basin and discharged via the waste outlet.

4. Maintenance of Wound Filter Cartridges

To maintain optimal performance over time:

– Prevent particle accumulation inside the filter that could block the system.
– Regularly inspect and maintain the filter to ensure efficiency.
– Periodically clean the filter, as a buildup of impurities over time can hinder performance.
– Ensure that the filter media remains moist to avoid drying out, which could negatively impact filtration precision.
– For dust removal systems, utilize blowing techniques to eject sticky materials without impacting filter performance, thus extending the filter’s lifespan.

By understanding the structure, filtration principles, characteristics, and appropriate applications of wound filter cartridges, users can maximize their impact and maintain high filtration standards for a variety of liquids across different industries.