In another article we discussed scrubber system, its working principles and overall design. Through following lines and paragraphs, we are going to meet the types of scrubbers and make a clear crystal distinguishment between the types, their individual designs and applications. Stay tuned with Linquip to learn what is necessary to know about the scrubber’s types.
As you know scrubbers are a varied group of air pollution control systems designed to remove particulates from industrial streams. They can eliminate up to 90% of emissions resulting in acid rains and other destructive environmental phenomena. In other words, using scrubbers of any types helps achieve a considerable removal of the harmful gas particles so that the streams of industrial sites are no longer damaging to the environment.
There are two major types of scrubbers that we are going to elaborate their applications and functions individually.
What is a wet scrubber?
Wet scrubber system is one of the main types of scrubbers that use wet or liquid substance, basically water to remove acidic contaminants from industrial emissions before they are released to environment. Flue gases in this system are funneled through an area and then sprayed by a wet substance which is usually water for dust or other solutions more effective for target certain contaminants like fuel gas. After that the liquid is misted through the gas and the gas comes out without pollutants that included before the exposure to the scrubbing liquid. Actually, when the gas is sprayed by the liquid the heavy pollutants are attached to the liquid. Misting the pollutants is the most common method used in this type of scrubber, in a different design, the gas is forced to bubble through a pool of scrubbing liquid. The method and result are the same; the contaminants bind to wet substance while the gas or dust is going to be filtered through the pool. Finally, the gas is clean and it emerges leaving the contaminants in the pool.
In both designs what is the same is the substance used to remove the contaminants. The scrubbers of this type are made of a ductwork and a blower system to force the polluted gas through its chamber. Besides, there is a pump and a collector area to detach the used wet substance from the pollutant-free gas. This scrubbing liquid is channelized away and collected for specialized disposal due to the fact that it may contain of the potentially harmful materials. This wet sprayed substance cannot easily be freed to the environment because of its chemical content.
These scrubbers are frequently used in most coal-fired power plants and other industrial plants that process propane and other types of natural and inorganic gases like sulfur dioxide, chromic acid, hydrogen sulfide, ammonia, chlorides and fluorides.
Advantages and disadvantages
There are a couple of advantages in the use of this type of scrubbers; these scrubbers are totally sturdy and stable and can tolerate a wide range of temperatures which are suitable for almost any environment. Moreover, these scrubbers support a wide range of contaminant refinement from sulfur to acidic gases having contributions to acid rains.
A few drawbacks have been seen in the operation of scrubbers of this type; these systems need frequent maintenances and because of employing liquid specially water as the removal substance, it can heavily suffer from corrosion. Having been maintained properly, it lasts for several years before it needs to be replaced.
What is a dry scrubber?
Dry scrubber is one of the types of scrubbers whose function is similar to the wet ones but unlike wet industrial scrubbers, this type doesn’t utilize a liquid to absorb contaminants. Because of this difference, a wastewater system is not needed. The system sprays a collection of dry chemical substances into exhaust steam. Depending on which material these dry substances are targeting for removal, they react differently. Some of them neutralize pollutants included in exhaust stream through a chemical reaction while others cause the contaminants turn into a different substance. This type of systems is built of a reaction center where the dry sorbent absorbing contaminants is mixed with the polluted gas. This type of scrubbers is used primarily to remove acids within gasses from combustion sources.
The process of removal is done by adding a series of dry reactants to gas. The whole process is accomplished in three steps of gas cooling, injection of dry purifying substances and filtering. To prepare the polluted gas it should be cooled. This step makes it easier to remove toxins from exhaust stream. After cooling the gas, reagent injection can begin. In this step, a variety of powders mixed and under high pressure are fired into polluted gas where chemical reactions happen and toxins of gas are removed. Through the last step all the used powders are captured by a filter and the purified gas exits the scrubbing chamber. Most of the time used powders can’t be re-used because they can’t be cleansed properly.
Advantages and disadvantages
Among the types of scrubbers, this type is more commonly used mainly due to the fact that they produce little waste materials in comparison with wet type. As most of the purifying powders sprayed into polluted gases are burned off in the heat of process or captured by the filter, the applying this type is less expensive. Moreover, in this type we have no excessive cost for removing, transporting and storing waste water of wet ones.
But the residual waste powders which are not burned should be disposal which is not possible every time. Another disadvantage is that the scrubbing process is expensive in this design. And finally, you should know that dry type can’t remove all the contaminants from the polluted gas.
Different types of scrubbers save our environment by rejecting and removing toxic harmful chemicals and acids. By employing one of right, suitable and compatible types of scrubbers, the environment, workers and people can breathe more pure and fresh air and other pollution phenomena won’t happen easily.
In this article we tried to tell all you need to know about the different types of scrubbers. We talked about their applications and functions. We discussed the advantages and disadvantages of each type and the decision is up to you. If you have any idea and opinion about this topic or obtained useful experiences over scrubbers, you can share it with us in comments and if you have a question about scrubbers which you didn’t find its answer, our experts in Linquip are ready to lead you. Just sign up and ask your questions.