Working principle of Venturi wet dust collector

The Venturi tube dust collector is a typical wet dust collector, and its dust removal mechanism is as mentioned above, which is mainly due to inertia, adhesion, and diffusion, and of course, inertia is the main factor.

When the dusty gas enters the contraction tube through the inlet duct, it gradually accelerates and is forced to pass through at high speed at the throat constriction. There are many small holes in front of the throat that spray water (or spray from the nozzle), and high-speed gas impacts and crushes the water into fine droplets, foaming into countless small water droplets (with a particle size of several hundred microns or less), which have a large contact surface area. The dust particles carried by the gas are thrown onto the slag droplet by the huge inertial force when the gas flows around the droplet and captured. The gas-liquid phase exits through the diffusion tube and enters the cyclone separator, where it is separated by centrifugal action.

During the dust removal process, the diameter of atomized water droplets should not be too large or too small. If it is too small, the separation equipment after dust removal (usually using cyclone separators) will have a low separation effect on these small particles and cannot meet the requirements of efficient separation. Experiments have shown that it is better for water droplets to be too small to be around 150 times the size of dust particles, otherwise efficiency will decrease. For high-temperature gases that are simultaneously defogged during the cooling process, the atomized water droplets should not be too fine, because regardless of whether dust particles are captured or not, the water droplets will shrink after evaporation. If the water droplets are too fine, they may even disappear after evaporation, greatly reducing the dust removal efficiency.

The atomization quality is related to the liquid to gas ratio and throat velocity, especially the latter. Because the energy for breaking water powder into droplets is mainly provided by high-speed gas, the higher the gas velocity, the greater the impact force, and the finer the water powder is broken; The smaller the air velocity, the larger the water droplet. Due to the lower gas velocity required for separating coarse dust particles, the energy consumption will also be lower, while separating fine dust particles will inevitably consume more energy.

Application in production

Venturi tube dust collectors are also used in phosphoric acid, phosphate fertilizer, and other chemical production processes. When burning molten phosphate fertilizer in a cyclone furnace, a Venturi tube defluorination and dust removal device is used for the treatment of fluorine-containing flue gas. When the gas velocity at the throat of the Venturi tube is controlled at 68-70m/s, the liquid to gas ratio is 0.46-0.51/Nm3, and the fluoride concentration in the flue gas is only 0.4-0.5l/Nm3, the fluoride removal efficiency can reach 90-96%. At the same time, the Venturi tube also has a high dust removal efficiency for lime in flue gas. The excess lime is mainly alkali metal oxides such as calcium oxide (CaO), which enter the liquid phase and react with hydrofluoric acid absorption solution, neutralizing the absorption solution to a pH value of 5. The Venturi tube also plays a role in defluorination, dust removal, and neutralization. Test data on defluorination and dust removal of gas purification device under optimal conditions