The self-excited wet dust collector achieves efficient capture of micron-sized particles through a unique gas-liquid interaction design. Its core mechanism revolves around four physical processes: inertial collision, diffusion, liquid film adhesion, and coagulation growth, forming a multi-layered particle capture system.
After entering the self-excited wet dust collector, the dust-laden airflow first violently impacts the pre-set liquid surface or film within the device. The high-speed impact of the airflow on the liquid surface shatters the surface, forming a large number of micron-sized droplets and foam. The size distribution of these droplets is closely related to the airflow velocity. During this process, particles larger than 0.3 microns, unable to change direction with the airflow due to inertia, collide directly with the droplets and become engulfed. This inertial collision mechanism is highly efficient for capturing large particles and is the primary method for removing coarse particles in the self-excited wet dust collector.
For fine particles less than 0.3 microns in size, diffusion becomes the key capture mechanism. These particles, impacted by gas molecules in the airflow, produce Brownian motion, resulting in an irregular, jagged trajectory. When particles move near droplets, they are captured by the sticky layer on the droplet's surface. Self-excited wet dust collectors optimize the droplet size distribution to ensure a sufficient number of tiny droplets are present for diffusion and collision with fine particles, thereby improving PM2.5 capture efficiency.
The liquid film adhesion mechanism plays a key role within the cylinder or channel of a self-excited wet dust collector. As dust-laden air flows along the wall, the persistent liquid film on the wall adheres to the moving particles. This mechanism is particularly effective for hydrophilic particles, as the surface tension of the water film holds the particles in the liquid layer, preventing secondary dust entrainment. Some self-excited wet dust collectors utilize rotating guide vanes or spiral channel designs to extend the airflow's residence time in the liquid film area, enhancing the film's ability to capture particles.
The coagulation-growth mechanism promotes the capture of fine particles through physical and chemical reactions. On the one hand, water vapor in the airflow condenses on the surface of particles, forming droplets that envelop the particles, and the particles grow in size by continuously absorbing water vapor. On the other hand, electrostatic attraction exists between the charged particles and the droplets, with opposite charges attracting each other, causing the particles to be captured by the droplets. The self-excited wet dust collector optimizes the coagulation conditions by controlling the humidity and temperature of the airflow. This allows previously difficult-to-capture submicron particles to grow through coagulation into larger particles that can be removed by inertial collision.
The unique structure of the self-excited wet dust collector further enhances this capture mechanism. Its core components include an impactor, a liquid level regulator, an entrainment separator, and a circulating water supply system. The impact device optimizes the nozzle structure to ensure that the airflow impacts the liquid surface at a specific angle and velocity, producing evenly distributed fine droplets. The liquid level regulator dynamically controls the liquid level to ensure the airflow impact point is always at the optimal position. The entrained particulate matter separator uses a centrifugal or baffle design to effectively separate entrained droplets from the purified gas, preventing secondary contamination. The circulating water supply system maintains the cleanliness and concentration of the liquid through filtration and water replenishment, ensuring long-term stable operation.
In practical applications, self-excited wet dust collectors have demonstrated their comprehensive advantages in capturing micron-sized particles. For example, in a sintering machine head dust removal project at a steel plant, particulate matter emission concentrations consistently exceeded standards when electrostatic precipitators were used before the retrofit. After the retrofit, the self-excited wet dust collector significantly reduced PM2.5 emissions by adjusting the liquid-to-gas ratio and airflow velocity, while also effectively removing acidic gases such as sulfur dioxide. This case study demonstrates the self-excited wet dust collector's ability to synergistically treat micron-sized particles and gaseous pollutants under complex operating conditions.
Technological trends indicate that self-excited wet dust collectors are evolving towards higher efficiency and greater intelligence. New devices utilize numerical simulation technology to optimize droplet size distribution, employ adjustable nozzles to dynamically adjust the liquid-to-gas ratio, and integrate online monitoring systems for real-time feedback on operating parameters. These innovations enable self-excited wet dust collectors to further enhance their capture efficiency and operational stability for micron-sized particles, while maintaining their traditional advantages of simplicity and low investment.
