How Wet Scrubbers Work

Wet Scrubbers are used in large industrial applications to remove pollutants from burning fossil fuels such as oil or coal and from waste gases in chemical processing plants. Using the simplest model, water is the most common solvent used to remove both particulates and gas contaminants in industrial applications. In the most basic form of wet scrubbers, water is encapsulated in a metal or composite container, contaminated gas is moved through the water, the water then absorbs the contaminates, and clean gas exits the scrubber. Aside from water, other liquids can be used as absorbing solutions to effectively remove varied contaminates. Changing the chemical composition of the absorbing solution changes the overall ionic charge, which can be highly positive, negative, or non-charged. Because pollutants differ in their charge, wet scrubbers are packed with the liquid that will bind most effectively to remove the contaminate from the gas.

AIR 1 Applied Sciences
There are similar pollutants in internal combustion engine (ICE) vehicles with gasoline or diesel engines and industrial waste gas and the exhaust of fossil fuel burning power plants. These can be best defined as Particulates and Gases. Wet scrubbers are generally the only single air pollution control device that can remove both categories of pollutants. The patent pending AIR 1 system is designed to remove particulates and gases using the best of these methodologies and applies them to a novel multi-stage scrubber system for any vehicle using an Internal Combustion Engine.

Stage 1 ~ Quench Reactor

Stage 2 ~ Impingement Tube

Stage 3 ~ Wet Bed Reactor

Stage 4 ~ Solution Treatment Module

Stage 1 ~ Quench Reactor
The first stage of the Air 1 system is the Quench Reactor where hot gases and particulates from a conventional catalytic converter enter an expansion chamber. The Reactor has a liquid injection nozzle which sprays a high-pressure liquid into the hot gas stream. This instantly drops the temperature of the gas, causing some pollutants to react with the liquid. This special fluid instantly turns into an extremely fine steam mist which mixes with the exhaust gases causing particulates and gas molecules to be absorbed or dissolved by the fine liquid droplets.

Stage 2 ~ Impingement Tube
The steam chamber is the section of exhaust pipe between the two reactors. It is here where the steam droplets continue to intermingle and “scrub” the exhaust gas from the Quench Reactor. The droplets continue to absorb pollutant particles and molecules from the gas stream.This can also be described as smog. (Smoke + Fog)

Stage 3 ~ Wet Bed Reactor
The third stage of the Air 1 system is the Wet Bed Reactor. This is an expansion chamber with another liquid jet nozzle to inject more scrubber liquid into the exhaust gas stream. This further cools the gas and begins the process of causing the steam droplets and pollutants to condense back into a liquid. The Wet Bed Reactor gets its name from a bed of stainless-steel ribbon sponge that the exhaust gas must pass through. Good gas-to-liquid contact is essential to obtain high removal efficiencies in absorbers. The WBR removes air pollutants through inertial or diffusional impaction within the matrix, forcing adsorption or reagent reaction of the liquid solvent. The sponge matrix provides a large, wet surface area and film for liquid-particle contact. This attracts the droplets to help them condense. The pollutants and steam droplets (SMOG) adhere to the wet surface of the stainless sponge matrix to separate them from the gas stream. The matrix also causes the gas to create vortexes and venturis which further cool the gas by Bernoulli’s principle yet offers little resistance to the exhaust gas. This feature is important for optimal engine performance. In fact, the Air 1 system is designed to have less restriction than a conventional OEM muffler. The WBR can be a stand-alone expansion chamber positioned before the muffler, or it can be incorporated into the first chamber of a modified muffler design. The cleaned gas passes through the matrix and enters the muffler and exits the tail pipe. The waste liquid drops to the bottom of the reactor chamber, and or muffler for collection and routing to a hose connected to the filtration stage.

Stage 4 ~ Solution Treatment Module
The final stage of the Air 1 system is the filtration stage, where the contaminated liquid is pumped and processed through a multi-stage filtration process. The make up of the filters are proprietary and involve various media of different ionic charges to cause coagulation of various molecules and particulates large enough to be trapped by absorption as well as adsorption within various filter media. The clean and recycled liquid is then pumped back to a holding tank where the system repeats the cycle of liquid injection into the reactors.

Wet Scrubbers in Coal Fired Plants & Industry

NOTE: The following paragraphs are related to current wet scrubber technology as used in coal fired plants and chemical processing and are offered here as a reference. It is from this information that the genesis of the AIR 1 concept was conceived.

Applicable Pollutants for Packed-Bed Wet Scrubbers
Packed-Bed wet scrubbers are used to control: Inorganic fumes, vapors, and gases (e.g., chromic acid, hydrogen sulfide, ammonia, chlorides, fluorides, and SO2) – Inorganic fumes, vapors and gases are the primary pollutants controlled by Packed-Bed wet scrubbers. They typically achieve removal efficiencies in the range of 95-99%. Volatile Organic Compounds (VOC) – Wet scrubbers are occasionally used to control volatile organic compounds (VOCs). Removal efficiencies for gas absorbers vary for each pollutant-solvent system and with the type of absorber used. Most absorbers have removal efficiencies in excess of 90%, and packed-tower absorbers may achieve efficiencies greater than 99% for some pollutant-solvent systems. The typical collection efficiency range is from 70% to greater than 99%. Particulate Matter (PM) and Hazardous Air Pollutants (HAP) in particulate form (PMHAP) – Packed-bed wet scrubbers are limited to applications in which dust loading is low, and collection efficiencies range from 50-95 %, depending upon the application. How Packed-Bed Scrubbers Operate Advantages of Packed-Bed Wet Scrubbers The advantages of Packed-Bed wet scrubbers are consistent with industrial scrubbers in general and include: • Relatively low pressure drop – Pressure drop is the pressure difference that occurs as exhaust gas is pushed or pulled through the scrubber, disregarding the pressure that would be used for pumping or spraying the liquid into the scrubber. • Fiberglass-reinforced plastic (FRP) construction permits operation in highly corrosive atmospheres • Capable of achieving relatively high mass-transfer efficiencies • The height and/or type of packing can be changed to improve mass transfer without purchasing new equipment • Relatively low capital cost • Relatively small space requirements • Ability to collect Particulate Matter (PM) as well as gases NOx (NO & NO2) Wet Scrubber The term 'Nitrogen Oxides' (NOx) is usually used to include two gases: Nitric Oxide (NO), which is a colorless, odorless gas and Nitrogen Dioxide (NO2) is a pungent gas that, along with fine airborne particulate matter, contributes to the reddish-brown haze characteristic of smoggy air in California and larger cities. NO2 is comprised of one atom of nitrogen and two atoms of oxygen, and is a gas at ambient temperatures. • High-efficiency wet oxidation/reduction approach to controlling nitrogen oxide (NOx) emissions • Single and multiple stage systems can provide more than 99% efficiency total NOx removal and elimination of the red/brown NOx exhaust plume • Minimal maintenance if thermoplastic construction is used for complete corrosion resistance. Quench Reactor • The Quench Reactor is where hot, corrosive air enters from the output from burning fossil fuels. The hot processes and corrosive air contaminants from catalytic oxidizers – HCl, HF, SO2, Cl2, HB • High efficiency – Up to 99.9% removal efficiency of acid or toxic gases • Maximum reliability and value with corrosion and chemical resistance materials • Two-stage system consists of: • Quencher stage designed to cool the hot gases – constructed of a suitable metallic material • Scrubber stage to remove the corrosive gases and mists – constructed of FRP material and is filled with a high efficiency packing material, mist eliminator and liquid distribution system Venturi Scrubbers Another popular type of wet scrubber is the Venturi scrubber. Venturis can be used to collect both particulate and gaseous pollutants, but they are more effective in removing particles than gaseous pollutants. where it collides with scrubbing water. The tiny water droplets capture particles through impaction and diffusion.