Spray washer

from Wikipedia, the free encyclopedia

A spray washer , washing tower , spray tower or nozzle washer is an apparatus for mass transfer and heat transfer between flowing gases and liquids. Spray scrubbers are the oldest type of gas scrubber and are used in particular for exhaust gas cleaning.

functionality

Functional principle of a spray washer operated in countercurrent

A spray washer is essentially a cylindrical container in which spray nozzles are installed in one or more levels, with which the gas flowing through the container is humidified. The number and arrangement of the nozzles depends on the container diameter. The container is largely free of built-in components, so that the resulting drops can fall down unhindered. The heat and mass transfer takes place at the phase interface between the droplet and gas. Particle separation takes place through the accumulation of the particles on the droplets due to inertial forces . The gas flow can take place both in cocurrent and in countercurrent . A droplet separator at the exit of the gas line prevents scrubbing liquid from being discharged.

The flow velocities in the countercurrent spray scrubber are usually between 1  m / s and 4 m / s with residence times between 10  s and 30 s. The pressure loss in spray washers is between 100  Pa and 200 Pa. The longer residence time compared to other washers favors diffusion processes .

commitment

Spray scrubbers are used to remove gaseous or particulate pollutants or contaminants from waste gases or process gases. Submicron particles, i.e. particles with a diameter smaller than one micrometer, are hardly separated by spray scrubbers due to the low relative speed between gas and liquid. Flue gas desulphurisation in fossil-fired power plants can be regarded as a typical application for spray scrubbers . The oxidizing scrubbing of sewage gases is also often carried out with the help of spray scrubbers. In combination with electrostatic precipitators , spray washers are operated as so-called wet electrostatic precipitators.

Another possible application for spray scrubbers is gas cooling, especially the rapid cooling of hot gases ( quenching ). The principle of the spray washer is also used for conditioning the supply air of air conditioning systems .

literature

  • VDI 3679 Part 1: 2014-07 wet separator; Basics, waste gas cleaning of particulate matter (wet separators; Fundamentals, waste gas cleaning of particle collections). Beuth Verlag, Berlin. ( Summary and table of contents online )

Individual evidence

  1. ↑ a b VDI 3679 sheet 2: 2014-07 wet separator; Waste gas cleaning by absorption (scrubbers). Beuth Verlag, Berlin. Pp. 33-35.
  2. ^ A b c d e Franz Joseph Dreyhaupt (editor): VDI-Lexikon Umwelttechnik . VDI-Verlag, Düsseldorf 1994, ISBN 3-18-400891-6 , p. 1106.
  3. ↑ VDI 3679 sheet 1: 2014-07 wet separator; Basics, waste gas cleaning of particulate matter (wet separators; Fundamentals, waste gas cleaning of particle collections). Beuth Verlag, Berlin. P. 32.
  4. ↑ Benedict Korischem, U. Werner: The gas dedusting in spray tower washers . In: Dust - cleanliness. Air . 54, No. 10, 1994, ISSN  0949-8036 , pp. 389-395.
  5. ↑ Matthias Stieß: Mechanical Process Engineering 2 . Springer-Verlag Berlin, Heidelberg, New York 1994, ISBN 3-540-55852-7 , p. 35.
  6. ↑ VDI 3679 sheet 4: 2014-10 wet separator; Waste gas cleaning by oxidative gas scrubbing (wet separators). Beuth Verlag, Berlin. P. 11.
  7. ↑ Martin Steinwender: Emissions from the wood-based panel industry - possibilities for reducing emissions when operating drying systems for the production of chipboard and fiberboard. In: Hazardous substances - cleanliness. Air . 61, No. 9, 2001, ISSN  0949-8036 , pp. 401-405.
  8. ↑ VDI 3679 Part 3: 2010-6 wet separator; Droplet eliminators (wet separators; mist eliminators). Beuth Verlag, Berlin. P. 48.