News Center

Filtering equipment is a mechanical equipment or device for filtering, and it is a common equipment in industrial production. Today, let's take a look at how our familiar and unfamiliar filtration equipment works.

Classification in different ways

1. Classify by operation mode: filter, continuous filter intermittently;

2. According to the difference of operating pressure: pressure filtration, suction filtration and centrifugal filtration;

3. Typical filter equipment used in industry: plate-frame filter press (intermittent operation), rotary vacuum filter (continuous operation), filter centrifuge.

Working Principle and Structure of Various Filtering Equipment

1. Plate-frame filter press

(1) Structure

It is composed of many filter plates with concave and convex lines and filter frames arranged alternately and assembled in the mechanism. It mainly consists of filter plate, filter frame, clamping mechanism, frame and so on.

Filter plate: a rough surface, convex part to support the filter cloth, groove is the flow channel of the filter. The round hole in the upper right corner of the filter plate is the slurry passage, and the round hole in the upper left corner is the washing passage.

Washing board: The washing channel in the upper left corner communicates with the grooves on both sides of the surface, so that the washing water enters the grooves.

Non-washing board: The washing channel is not connected with the grooves on both sides of the surface.

Filter frame: filter passage: round hole in the upper right corner of the filter frame; washing passage: round hole in the upper left corner of the filter frame

In order to avoid the incorrect installation sequence of the two plates and frames, one, two or three small buttons are often cast on the outer side of the plates and frames. The non-washing board is a button board, the frame has two buttons, and the washing board is a three-button board.

(2) Operation process

The plate and frame filter press is intermittent operation. Each operation cycle consists of five stages: loading, filtering, washing, discharging cake and cleaning.

Installation: The plate and frame are arranged in the order of 1-2-3-2-1-2-3. The filter cloth is placed on the two sides of the filter plate, and then fixed by manual or mobile compression device to make the plate and frame contact closely.

Filtration: The suspension is fed into the slurry passage under the specified pressure and flows into each filter frame through the passage; the filtrate passes through the filter cloth on both sides of the filter frame separately and discharges along the channel on the surface of the filter plate to the outlet of the filtrate; the particles are intercepted by the filter cloth and deposited on the filter cloth until the cake fills the whole frame, then the filtration stops. According to the way of filtrate discharge, it can be divided into open flow and dark flow.

Washing: Washing water enters the two sides of each washboard through the wash path from the hole on the washboard. The wash water first passes through a layer of filter cloth and the filter cake with the whole frame thickness under the impetus of pressure difference (the filter outlet on the washboard is closed), then passes through a layer of filter cloth, and finally discharges along the channel on the surface of the filter board (a button board) to the outlet of the filtrate. This method of operation is called cross-washing method. The washing water passes through twice as much as the filtrate passes through at the end of the filtration, and the flow area is half of the filtration area. Dreg unloading and finishing: Open plate and frame, unload filter cake, wash filter cloth, plate and frame.

(3) Characteristics

The utility model has the advantages of simple structure, low price, small floor area and large filtering area.

The number of filter plates can be increased or reduced according to the need, and the filtration capacity can be adjusted.

Because of the high operating pressure (3-10kg/cm2), it can also be applied to filters with small particles and high liquid viscosity.

Intermittent operation, low production capacity, slag discharge cleaning and assembly stage requires manual operation, labor intensity, so it is only suitable for small-scale production.

2. Pressure leaf filter

The leaf filter is composed of many rectangular filters with different widths. The filter blade is made of wire mesh with space inside and filter cloth outside.

Leaf filters are also operated intermittently. When filtering, the filter blades are installed in a sealed housing capable of withstanding internal pressure. The filter slurry is pumped into the housing, passed through the filter cloth into the hollow part of the screen, and then assembled into the lower main pipe and then flowed out. Particles are deposited on the filter cloth to form a filter cake. When the cake accumulates to a certain thickness, the filter stops.

When washing, the path of washing water is the same as that of filter liquid. This washing method is called displacement washing method.

The advantages of leaf filter are compact equipment, closed operation, better working conditions, no loading and unloading of filter cloth every cycle, and less labor.

3. Rotary Vacuum Filter

(1) Structure of Rotary Vacuum Filter

Rotary vacuum filter is one of the most widely used continuous operation filters in industry. The main body of the equipment is a rotating horizontal cylinder. The surface of the cylinder is covered with a metal mesh. The lower part of the cylinder enters the filter slurry. The cylinder is divided into several fan-shaped lattices along the radial direction, each with a separate channel leading to the distribution head. When the cylinder rotates, these channels are connected with the vacuum tube and the compressed air tube in turn by the function of the distributor head. Therefore, in the process of turning around a week, the surface of each sector lattice can be filtered, washed, sucked, bleached and discharged sequentially.

(2) Structure and Working Principle of Distribution Head

The distribution head consists of a tightly attached rotating disc and a fixed disc. The rotating disc rotates with the cylinder body. The grooves on the inner surface of the fixed disc are connected with various pipes with different functions. When the fan-shaped lattice 1 begins to enter the filter slurry, the corresponding small holes on the rotating disc are relative to the groove f on the fixed disc, thus connecting with the vacuum pipeline and sucking up the filtrate. The position of the fan-shaped lattice 1-7 in the figure is called the filter area.

After the fan lattice is turned out of the filter groove, it is still connected with the groove F and continues to dry the filtrate remaining in the filter cake. The location of the fan lattice 8-10 is called the filter drying zone. When the fan-shaped lattice rotates to the position of 12, the washing water is sprayed on the filter cake. At this time, the fan-shaped lattice communicates with the groove G on the fixed plate and sucks the washing water through another vacuum pipe.

The location of sector lattices 12 and 13 is called washing area. Sector lattice 11 corresponds to the groove F and G on the fixed disc, which is not connected with any pipeline. This position is called no working area. When the sector lattice is transferred from one area to another, the operation areas are not colluded with each other because there is no workspace.

4. Stirred Parent Reversible Fiber Ball Filter

Working principle:

Parent reversible fibers are used as filters, which keep the original fibers flexible, compressible, high porosity and strong anti-fouling ability. When working, the pore of the filter layer is loose and compact, which conforms to the ideal pore distribution of the filter layer. It is larger than water, easy to back wash, good material, strong corrosion resistance and chemical erosion resistance.

So it can intercept the tiny suspended matter which is not easy to be removed by precipitation. According to the water quality of different water sources, different types and performances of filters can achieve satisfactory results. The equipment is suitable for high-precision filtration of oil-bearing suspended matter such as oil field water injection, oil depot cleaning water, mechanical processing and so on.

5. Filter centrifuge

Centrifugal filtration refers to the operation process in which the centrifugal force exerted by rotating liquid is intercepted on the surface of the filter medium through media, filter cake and solid particles. The driving force of centrifugal filtration is centrifugal force.

6. Cyclone Separator

Cyclone separator is a device for purifying gas by centrifugal force.

(1) Characteristic: It has simple structure, convenient manufacture, high separation efficiency, and can be used for separating high temperature dusty gas;

(2) Structure: outer cylinder; inner cylinder; conical cylinder.

(3) Working process:

Work process: Dusty gas enters from the tangent line of the long square on the cylinder. The inlet gas velocity is about 15-20 m/s.

Dusty gas rotates along the inner wall of the cylinder. The centrifugal force of the particles is larger, and the particles are thrown outwards and the air flow is in the inner layer. Gas and solid are separated.

In the conical part, the rotating radius decreases while the tangential velocity increases, and the airflow and particles spiral downward.

Near the bottom of the cone, the airflow turns upward and rotates, and eventually it is discharged from the upper outlet pipe; the solid phase falls into the ash hopper along the inner wall.

7. bags of filters

(1) Structure

Filter bag, skeleton, chassis, ash cleaning device, ash hopper, ash discharge valve.

(2) Working process

Dusty gas enters the bag filter.

The gas passes through the filter bag and is discharged from the top.

Dust is intercepted.

After gathering a certain thickness of dust, compressed air enters, the filter bag vibrates and the dust falls.

Dust is removed by the dust discharge valve.