Filtration refers to a unit operation of separating solid particles suspended in gas or liquid. A porous material is used to pass the gas or liquid in the suspension, and the trapped solid particles are stored on the filter medium to form a filter cake. Filtration operations are widely used in various chemical production, especially for separating solid particles in liquids, and also for separating dust from gases, such as bag filters.

Industrial filter is one of many filters, widely used in metallurgy, chemical industry, petroleum, papermaking, medicine, food, mining, electric power, urban water supply fields. Such as industrial waste water, circulating water filtration, emulsion regeneration, waste oil filtration treatment, continuous casting water system, blast furnace water system in the metallurgical industry, high-pressure water descaling system for hot rolling. It is an advanced, efficient and easy-to-operate automatic filter device.

Generally speaking, the mixture to be filtered is called the filter slurry, the clear liquid passing through the filter medium is called the filtrate, and the trapped solid particle layer is called the filter cake.

The filtration of gas-solid mixture is generally carried out under the action of pressure difference. The purpose of the filtration operation is sometimes to obtain a clarified fluid, such as filtration of lubricating oil or air; sometimes to obtain suspended solid particles, such as separating the crystal product from the mother liquor during crystallization; sometimes it is both.

According to the driving force of the process, filtering methods can be divided into:

①Gravity filtration, the operating driving force is the static pressure of the liquid column of the suspension itself, generally not more than 50kPa, this method is only suitable for processing filter slurry with large particle size and low content;

②Pressurized filtration, pressurizing the filter slurry with a pump or other means, can produce a higher operating pressure, generally up to 500kPa or more, which can effectively handle the difficult-to-separate filter slurry;

③Vacuum filtration, draw a vacuum on the bottom side of the filter medium, the resulting pressure difference is usually no more than 85kPa, suitable for filter slurry containing mineral or crystal particles, and easy to wash the filter cake;

④ Centrifugal filtration, the operating pressure is the centrifugal force generated by the filter slurry layer, which is convenient for washing the filter cake. The resulting filter cake has a small liquid content and is suitable for the filtration of crystal materials and fiber materials.

There are many types of filtering equipment. Generally, the machine that implements gravity filtration, pressure filtration and vacuum filtration is called a filter; the machine that implements centrifugal filtration is called a centrifugal filter. The mechanism can be divided into surface filtration and deep filtration according to the mechanism of filter media intercepting solid particles. The former is widely used in chemical production; the latter is less used.

The core component of the filtration equipment is the filter element of the filter screen. How to choose the most suitable filter element is a key step.

 

In industrial filtration, the most common, most durable, and most reliable filter element is the wedge wire filter. The stainless steel wedge wire filter screen is a multi-functional screen with toughness and anti-clogging properties, in which triangular "wedge wires" are arranged at equal intervals to form suitable gaps/slits (screen holes). They can be used for filtration, solid-liquid separation, classification, dehydration, concentration, etc., regardless of their industry or geographic location.