Scrubber

A scrubber (English scrubber ) or absorber is a procedural apparatus in which a gas stream is brought into contact with a liquid stream to absorb components of the gas stream into the liquid.

For those over previous components of the gas stream may be solid, liquid or gaseous substances. The wash liquid can be pure solvent such as water, as well as suspensions, such as milk of lime ( FGD ), are used. The more general term absorber or absorption column is used in particular when the aim of the process is not the emission and absorption of solid components is of minor importance.

In rare cases, storage catalysts with a fixed active component or in a solid matrix fixed liquid component are incorrectly referred to as a scrubber. In these cases, the storage catalysts have a gas scrubber replaced in the process. However, the name given to the cleaning of the gas flow was maintained.

Construction

In most designs, the scrubber is divided into six areas. From bottom to top they have the following problem:

  • In the bottom of the scrubber collects the washing liquid and is drawn off,
  • In the gas inlet, the gas is given by internals and reaches a uniform load of the interior,
  • In the Contact section, the washing out of the gas stream located in the ligand components takes place,
  • In the scrubbing liquid supply the washing liquid is applied and distributed,
  • In drip entrained components of the washing liquid are separated and
  • In the head leaving the purified gas stream the scrubber.

Principle of operation for the gaseous components

The scrubber works similar to the rectification column by repeated mixing and separation processes of the liquid and gaseous phase with formation of phase equilibria. In contrast to the rectification column, there is the gas scrubber as well as in the extraction column no return. Although the physical functions are identical is rather spoken for sets with simple mechanical construction of more gas scrubbers and more complex apparatus of wash columns.

The efficiency of the scrubber is determined by

The efficiency can therefore be increased by

By mechanically simple construction also suspensions as lime can be used as washing liquid. This used in flue gas desulfurization process is a Reaktivextrakion.

Operating principle for solid or liquid components

The washing liquid is sprayed at high speed and in small drops through the gas. The gas must pass through the washing liquid such as by a curtain. Are the drops of washing liquid quickly enough, the particles in the gas stream can no longer avoid the drop and merge them into larger drops. These larger droplets can then be deposited with the drip.

The dust collection efficiency is relatively low when working with medium and low pressure scrubbers.

Areas of application

Include:

  • A device which is commonly used in the exhaust ducts of large furnaces.
  • Industrial combustion exhaust gases may contain environmentally hazardous substances which are either filtered out by the scrubber or at least neutralized.
  • The amine washing (removal of acid gases, especially hydrogen sulfide and carbon dioxide from natural gas and biogas mostly by mono - and diethanolamine as a detergent).
  • In semiconductor technology, emissions must be cleaned of process plants. Different hydrolysable silanes and corrosive gases, such as HCl or amines can be removed by a scrubber.
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