Sintered metal fiber felt

What is a sintered metal fiber felt filter element

Sintered metal fiber felt filter element refers to the filter element with sintered felt as the filter medium, and the sintered metal fiber felt is made of metal fibers with a diameter of micrometers through non-woven laying, stacking and high temperature sintering. The multi-layer metal fiber felt is composed of layers with different pore sizes to form a pore gradient, which can be controlled to obtain extremely high filtration accuracy and a larger dirt holding capacity than a single layer. The main materials of sintered fiber felt filter elements are generally 304, 316 stainless steel, iron, chromium and aluminum.

Why choose sintered fiber felt filter

The sintered fiber felt filter element can be used repeatedly for many times, and the service life of the filter screen is very long, which effectively saves the production cost. The sintered felt filter element is made of metal, has strong wear resistance and good rigidity, and is not easy to deform during use. And easy to clean. Sintered fiber felt filters are an economical and convenient solution not only in industry, but also in air ventilation and air conditioning intake equipment. The resistance of the metal filter is very low, which can be easily cleaned repeatedly.

Product category

How sintered fiber felt is processed

The welding of the lap joints of the sintered fiber felt is carried out by diffusion. In the early stage of sintering, the overlapping points of the fibers in contact with each other gradually form the connection of the sintered felt. At this time, the overlapping points are discontinuous and have a large number of pores. The main mechanism of diffusion is surface diffusion; in the middle of sintering, the pores of the sintered felt gradually disappear, Grain boundaries are gradually formed in the sintered felt, and the main diffusion mechanism at this time is grain boundary diffusion; in the later stage of sintering, the grains near the sintered felt begin to grow, and the bulk diffusion of grain growth is the main mechanism at this time. The essence of diffusion is the thermal motion of atoms, and temperature significantly affects the rate of atomic diffusion. For surface diffusion, sintered felt can only be formed when the sintering temperature is sufficient for the thermal motion of atoms on the fiber surface to overcome the surface energy barrier, so fiber sintered felt. should exceed a certain temperature. Similarly, the sintering temperature affects the diffusion speed of fiber atomic grain boundaries. The higher the sintering temperature, the faster the grain boundary diffusion speed and the faster the fiber sintering felt; but too high sintering temperature will cause the fiber to have too large grains and shrinkage of the wire diameter. And defects such as over-melting, which need to be avoided in the fiber sintered felt process.

Sintering method

The sintering methods mainly include the following:
1. Normal pressure sintering method: Under normal atmospheric pressure and atmosphere conditions, sintering is carried out at the required temperature and time according to the material. Atmospheric pressure sintering has low cost and is the most common sintering method.
2. Hot pressing method: The powder filled in the mold is heated in a uniaxial direction while being pressurized. Sometimes the temperature rises and then pressurized. The high-frequency induction method is almost always used for heating. The material sintered by this method has high strength and good compactness.
3. High temperature isostatic pressing method: This method subjects the material to isotropic pressure, so that it can be sintered at a very low temperature, making it possible for materials that cannot be sintered under normal pressure to be sintered.
The product obtained by this method has excellent performance and is unmatched by other methods, but the high temperature isostatic pressing equipment and its operation cost are expensive.

The production stage of the sintered felt filter process

1. Low temperature burn-in stage
At this stage, the recovery of metal, the volatilization of adsorbed gas and moisture, and the decomposition and removal of the forming agent in the compact mainly occur.
2. Medium temperature heating and sintering stage
At this stage, recrystallization began to occur. Within the particles, the deformed grains were recovered and reorganized into new grains. At the same time, the oxides on the surface were reduced, and sintering necks were formed at the grain interface.
3. High temperature heat preservation to complete the sintering stage
The diffusion and flow in this stage are fully carried out and nearly completed, and a large number of closed pores are formed and continue to shrink, so that the pore size and the total number of pores decrease, and the density of the sintered body increases significantly.

Sintered felt parameters

Materials: 316-L stainless steel, 316 stainless steel, 304 stainless steel, nickel, iron chromium aluminum.
Absolute filtration class: For liquids: 1µm to 80µm, for air and gases: below 0.1 µm is possible.
Standard size: 500mm×1000mm, 600mm×1000mm, 600mm×1200mm, 1000mm×1000mm, 1000mm×1200mm, 1000mm×1480mm, 1180mm×1450mm, 1180mm×1500mm.
Maximum size: 1500mm x 1800mm.

Performance advantages

1. High strength, good rigidity: high mechanical strength and compressive strength, good processing, welding and assembly performance, easy to use.
2. Uniform and stable precision: Uniform and consistent filtration performance can be achieved for all filtration precisions, and the mesh does not change during use.
3. Wide range of use environments: it can be used in temperature environments of -200 ° C ~ 600 ° C and filtration in acid and alkali environments.
4. Excellent cleaning performance: good countercurrent cleaning effect, can be used repeatedly, and long life (can be cleaned by countercurrent water, filtrate, ultrasonic, melting, baking, etc.).

Application

1. Filtration and purification of various polymer melts in chemical and film industries;
2. Filtration of various high temperature and corrosive liquids in petroleum and chemical fields;
3. Precision filtration of various hydraulic oils and lubricating oils for machinery and equipment;
4. Clarification and filtration of various liquids in medicine, biology, beverage and other industries.

Cleaning method of sintered felt filter elements

1. Backwashing is generally selected on the production line: firstly close the switch of the raw liquid and filtrate pipelines, rinse with bacteria-free water, input from the original outlet, and discharge from the inlet or the lower drain hole of the filter. Large, generally around 5 kg.
2. Remove the sintered felt filter element and clean it in the cleaning solution, first soak it in the cleaning solution for repeated cleaning.
Cleaning fluids are generally available:
A. Sodium hydroxide, 0.1N NaOH
B. 1-2% citric acid water flux or 0.1N oxalic acid solvent, 0.1N hydrochloric acid solvent.
C. When cleaning with other solvents such as enzyme solvent, it is generally better to control the temperature at 30-40 degrees.
Matters needing attention when cleaning: After filtering the sintered felt filter element with high protein content, such as draft beer, nutrient solution, etc., it must be disinfected at high temperature to prevent the protein from agglomerating at high temperature and blocking the membrane pores.

Sintered metal fiber felt filtration process

The first stage (that is the stable stage): the metal fiber sintered felt filter filter material is initially clean, and its material structure and shape are fixed. In the initial stage of filtration, when the dust-laden fluid passes through the pore channels of the filter material, various filtration mechanisms are used. Under the joint action, the fluid mixed with the polluting particles will quickly dissipate, fill up the various channels of the filter material, and accumulate on the surface of the inner pores or the surface of the filter material. At this time, the resistance of the filter material is relatively stable. This stage is actually short-lived and will end soon.
The second stage (that is the non-stable stage): as the pores of the filter material become more and more narrow, or even gradually blocked, the pollutant particles continue to accumulate on the surface of the filter material to form a filter cake and form a new filter layer. It is the main working condition of the filter material. In this state, the polluted particles in the system are subject to the double filtration of the filter cake and the filter material at the same time. At this time, the resistance of the filter material continues to rise, and the filtration effect is in an unstable state. Its filtration efficiency It is much higher than the filter cake on the surface of the filter material.

Precautions for the use of sintered felt pleated filter element

1. The superalloy powder sintered felt pleated filter element is a consumable item. Although it is more durable than other filter elements, care should be taken not to scratch, touch, smash, or drop during cleaning and disassembly to prevent man-made damage. It is strictly forbidden to use tools to apply force to the surface of the filter element.
2. Under normal circumstances, the filtrate is filtered from the outside to the inside of the filter element, and reverse filtration is not recommended.
3. When filtering, slowly pressurize to the required working pressure, and it is strictly forbidden to open the valve to pressurize quickly.
4. When the maximum working pressure is less than or equal to 3MPa and the filtration efficiency is lower than 50%, clean air or clean liquid should be used for online backflushing in time.
5. When the superalloy powder sintered felt folded filter element is used for backflushing and backflushing, it is generally backflushed with pure gas first. The backflushing pressure is 1.2-1.5 times the working pressure. The backflushing time is 3-5 seconds each time, and the operation is repeated. After 4-6 times, backwash with cleaning solution, backwash for 3-5 minutes, and operate 2-3 times.
6. If the pressure loss is still serious after the sintered felt folded filter element is backflushed and backwashed online, it should be removed in time for cleaning