Venturi scrubbers, in combination with filter bags, are highly effective air pollution control systems used to remove particulate matter, including dust and fine particles, from industrial gas streams. These systems are widely employed in various industries to ensure compliance with environmental regulations and improve air quality.
Gas Inlet and Acceleration: Dust-laden gases from industrial processes enter the dust collector through the gas inlet. The gases are accelerated as they pass through the converging section of the Venturi scrubber and reach high velocities at the Venturi throat. This acceleration facilitates effective contact between the dust particles and the liquid introduced in the next stage.
Introduction of Liquid and Initial Particle Capture: As the gas stream approaches the Venturi throat, a liquid (usually water) is introduced into the gas flow. The liquid is dispersed into fine droplets using spray nozzles or other atomization methods. The water droplets mix with the dust-laden gas, creating a mist of tiny water droplets throughout the gas stream.
a. Venturi Scrubbing: The water droplets act as a medium for capturing dust particles through mechanisms such as inertial impaction and interception. The larger particles collide with the water droplets, and smaller particles are intercepted as they come into contact with the droplets.
Particle Agglomeration: As the dust particles come into contact with the water droplets, they adhere to the droplets' surfaces and become wetted. This process leads to the formation of larger agglomerated particles composed of multiple dust particles and water droplets.
Introduction of Filter Bags: To further enhance the dust collection efficiency and remove finer particles that may not be effectively captured by Venturi scrubbing alone, a series of filter bags are strategically placed downstream of the Venturi scrubber. These filter bags are made of porous fabric materials, such as polyester, polypropylene, or fiberglass, designed to trap particulate matter while allowing the clean gas to pass through.
Particle Capture by Filter Bags: As the gas stream enters the filter baghouse, the agglomerated particles, as well as finer dust particles not captured by the Venturi scrubber, are directed into the filter bags. The particles collide with the surface of the filter bags and adhere to the fibers due to various filtration mechanisms such as inertial impaction, interception, and diffusion.
Clean Gas Outlet: After passing through the filter bags, the gas stream is substantially cleaned, and the captured dust is retained within the filter bags.
Periodic Cleaning of Filter Bags: Over time, dust accumulation on the filter bags can reduce their efficiency. To maintain optimal performance, the filter bags require periodic cleaning. This can be achieved through various methods such as pulse-jet cleaning, reverse-air cleaning, or mechanical shaking, where the accumulated dust is dislodged from the filter bags and collected in hoppers for disposal or recycling.
By combining Venturi scrubbers and filter bags, dust collectors can achieve high removal efficiencies for a wide range of particulate matter, including both coarse and fine particles. This combined approach ensures compliance with environmental regulations and contributes to cleaner air and safer working environments in industrial settings. However, proper design, operation, and maintenance are essential to maximize the overall efficiency and longevity of the dust collector system.
