Dust removal equipment: The equipment that separates the dust from the flue gas is called a dust collector or a dust removal device. Everyone has the experience of wearing a mask. A mask is a simple filter dust removal device. The dust removal mechanism of the dust removal equipment is very simple. Like the dust removal mechanism of the mask, it is achieved through the mechanical interception of the fly ash particles in the flue gas by the filter material. But in addition, the fly ash particles received first form a stable layer of dense ash on the surface of the filter material (commonly known as filter cake or filter bed), which in turn plays a very good filtering role. It is a dust removal device that uses a cloth to make filter bags. This filter bed plays a major role in filtering.
Filter element: The filter element can be made of cotton fiber, glass fiber or various chemical fibers through textile (or needle punching) into filter material and then sew into vertical hanging filter bag. Different filter media should be used in different occasions. The dust collected on the filter bag deforms the bag and removes the ash through periodic mechanical shaking, filtered back-flushing of the smoke, or pulsed back-flushing of the compressed air.
The filter cake (filter bed) that the flue gas can pass through the filter bag and the filter material surface depends on the pressure difference between the two sides of the filter layer – this pressure difference is usually called the tube sheet pressure difference d.p. (sometimes called the filter bed pressure difference). In the collection of fly ash, a special parameter is the speed at which the smoke is filtered—the amount of air that is filtered per square meter of filter cloth. The pressure difference d.p. of the filter bed is linearly proportional to the smoke velocity, and therefore is also linearly proportional to the flue gas flow. This fixed ratio coefficient is often called filter resistance. According to this definition, the filter resistance is independent of the flue gas flow and is somewhat similar to the concept of resistance. We express the average filtration rate as the air-to-cloth ratio, which is the ratio of the amount of flue gas to the entire filtration area (in m3/m2/min). This parameter is a very important technical indicator in the selection and design of baghouse dust removal equipment.
The remaining pressure loss of the bag dust removal equipment is generated by the flue and baffle doors between the inlet flanges of the bag dust removal equipment. The magnitude of this pressure drop is proportional to the square of the flow velocity of the flue gas, so the pressure drop Δp. and the flue gas amount of the entire baghouse dust removal device are in a quadratic relationship.
Δptotal=K1Q1 K2Q2
K1=Kdrag/A (Kdrag=Filter resistance, A=Filtered surface area)
K2 = pressure loss coefficient of flue gas duct and damper door Q = volume of flue gas
The performance of the dedusting equipment is expressed in terms of the amount of gas that can be handled, the resistance loss when the gas passes through the dedusting equipment, and the dedusting efficiency. At the same time, the price, operation and maintenance costs of dedusting equipment, the length of service life, and the ease of operation and management are also important factors in considering its performance.
Dust removal equipment is divided into the following five categories according to its principle of action:
(1) Mechanical dust removal equipment includes gravity dust removal equipment, inertial dust removal equipment, and centrifugal dust removal equipment.
(2) Washing dust removal equipment includes water bath dust removal equipment, foam dust removal equipment, Venturi tube dust removal equipment, and water film dust removal equipment.
(3) Filter dust removal equipment includes bag dust removal equipment and particle layer dust removal equipment, etc.
(4) Electrostatic dust removal equipment.
(5) Magnetic dust removal equipment.
The inertial dust removal device is a dust removal device that causes dust-containing gas to collide with a baffle or drastically change the direction of the air flow, and uses inertial force to separate and trap dust. Inertia dust removal equipment is also called inert dust removal equipment.