Further developments of existing processes and procedures in environmental technology form a focal point for operators and manufacturers. Wet air scrubbers remain the main force for the capture and collection of particulates. Whether a wet-working or a dry system should be applied is determined by the particular characteristics of the dust in question: small dust particle sizes favor the Venturi scrubber. Venturi scrubbers are successful in removing particulates from exhaust gases with high efficiency. This type of dust control technology is a part of the group of air pollution controls collectively referred to as “wet scrubbers”. Venturi scrubbers are also known as Venturi jet scrubbers, gas-atomizing spray scrubbers, and ejector-venturi scrubbers. Properly designed and operated wet scrubbers are effectual in taking many regulated heavy metal compounds and some acid gases away with the help of special air treatment equipment. Scientists and engineers apply impingement trays or packed tower scrubbers for additional acid gas collection and also to subcool the gases after the removal of particulates from the gases through the use of Venturi scrubbers in their work. This minimizes the horsepower required by the induced draft fans. Venturi scrubbers have several advantages compared to other air pollution control equipment: such wet scrubbers are able to handle high-temperature gas streams or such gas streams that contain moisture. In addition to this, the overall size of dust control equipment is typically smaller, and Venturi wet air scrubbers have the potential for removing pollutant gases at the same time as particulates.
Venturi wet scrubbers are the most popular type of scrubbers; they have been used in the industry of air scrubbing for the past 35 years. This popularity is explained by its high efficiency of particle collection, open construction, the ability to handle large inlet volumes at high temperatures.
A standard Venturi scrubber is a combination of a converging section with a throat (the narrowest part of the whole tube), and with a diffuser. The mixture of dust and gas flows through the tube of the Venturi scrubber and reaches top speed in the throat section. This top speed drops again when the mixture passes into the diffuser. Intensive and concerted mixing takes place in the throat section between the gas and the liquid. Due to the high speed realised by the gas and liquid water is released into fine water droplets. The collection object in a typical Venturi scrubber is a liquid drop. The diameter of a liquid drop is a complicated function of velocity, liquid rate, and fluid properties. A centrifugal fan installed upstream (forced draft) or downstream (induced draft) provides the motive force to the gas stream carrying the PM (Particulate Matter). The gas is accelerated to the throat velocity in the converging inlet. After that, the gas passes through the throat where the PM encounters the liquid drops. It is necessary to mention that Venturi scrubbers themselves have a low volume: the droplet separator determines the dimensions of the installation. Such separator can be a few times larger than the scrubber.
Despite the popularity of Venturi scrubbers and their seemingly open and low maintenance design, it is not devoid of construction flaws. One of them is a possibility of converging section corrosion due to a dry hot gas entering the scrubber. This can wear down the scrubber and cause a breakdown. To avoid that, cleaning liquid is introduced in the first section, instead of the second to cool down the air and stop dust particles from wearing down the surface of the scrubber.
Another problem that can occur is dust and particle collection on the venturi throat. This section is not easy to get to, and if not cared for properly, can decrease venturi air scrubber efficiency and eventually lead to the breakdown of the scrubber. A solution to this problem is a dispersion of a cleaning liquid onto the surface of the throat to protect it from particle buildup.
Being a new type of wet air scrubber, multi-vortex wet air scrubber provides improved air treatment quality and can be used for both particles matter and gas collection. The treatment quality of multi-vortex wet air scrubber is generally 99.95-99.99% for both types of pollutants. Besides high efficiency, multi-vortex wet air scrubber possesses a number of advantages over conventional wet scrubbers – multi-vortex wet air scrubber is compact, omnivorous, eco-friendly, economical, and low-maintenance.