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INDUSTRY NEWS


May/June 2022
SOLVE IT!
20 +20 + 20 = 60.
How can you make 60 again using the same number three times, but it can't be 20?

IS A WET SCRUBBER RIGHT FOR YOUR APPLICATION?

With collection efficiencies of over 99%, wet scrubbers can effectively remove particulates, vapors and gases from the exhaust stream of a process. When should you consider a wet scrubber? They are a good option for any of the following: wet or sticky particulate, soluble particles, fine particles or mists, mixes of particulate, gases and vapor and combustible dust.

Below is a summary of the four main types of wet scrubbers, as well as the advantages and disadvantages of wet scrubbers compared to dry dust systems. As with any system, to maximize collection efficiencies start by understanding your application needs.
PROS AND CONS OF WET SCRUBBERS
Advantages

Safely handles combustible dust.
In applications involving combustible dust, a wet scrubber eliminates the risk of an explosion in the scrubber. Dry systems require safety equipment to avoid dust related explosions. That, along with the ongoing maintenance for dry systems, adds to the cost.

Saves space.
Without the ductwork needed for baghouses and cartridge collectors, wet scrubbers consume less space in the plant allowing for more flexibility in the site location.

Handles sticky materials
In dry systems, sticky material can quickly clog filters increasing the cost of labor and replacement filters. Wet scrubbers have no filters.

Removes unwanted soluble gases.
Wet scrubbers can collect both gases and particulate matter, as well removing water-soluble odors. In contrast, dry dust collection systems do not remove gases and odors.

Handles high temperature and moisture
Wet scrubbers have no temperature limits or condensation problems like those that can occur in baghouses. 

No secondary dust sources
Once collected, particulate cannot escape from hoppers or during transport.

Minimize maintenance.
The only regular maintenance required is to regularly change the scrubber water. The frequency depends on the CFM of the system, the amount of particulate in the influent gas, and the PPM targets required of the effluent gas.
Disadvantages

Corrosion
Because liquid solutions are more corrosive than dry dust, wet scrubbers must be constructed of stainless steel, increasing the cost. Baghouses, cartridge collectors, and dust cyclones may be made of cheaper carbon steel. Depending on the nature of the particulate, in some applications a dry dust collection system may also need to be made in stainless steel, diminishing the cost advantage.

Difficulty of wet waste disposal
Dirty water must be changed as a wet scrubber collects contaminants. The liquid wastewater requires treatment before disposal. Ash ponds, settling ponds or sludge clarifiers are sometimes used to meet wastewater requirements.

High Power Requirements
With wet scrubbers, high pressure drops are required to achieve the desired collection efficiencies for particulate matter. High-horsepower fans apply the force to mix the exhaust gas with the water. Compared to dry dust collection systems that merely move gas through a filter, a wet scrubber adds more to the electric utility bill.

Maintenance Costs
Maintenance costs are high for corrosive materials. Solids can build up around the wet-dry interface requiring regular maintenance.

Product Recovery
Dewatering and drying of scrubber sludge make recovery of any dust for reuse expensive and difficult.
For more information, contact Sly, Inc or your TEC representative.
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