Venturi scrubber

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A venturi scrubber is an apparatus for the exchange of substances between flowing gases and liquids. The scrubber , which works on the principle of the Venturi nozzle , is used in particular to separate dust from exhaust gases . The first venturi scrubbers came on the market in the second half of the 1940s.

functionality

Functional principle of a venturi scrubber

In a Venturi scrubber, the flowing dust-containing gas is passed axially through a jacket tube, which consists of a convergent part, the throat and a diffuser . The gas is accelerated towards the throat and has its lowest pressure there. In the diffuser, part of the kinetic energy of the gas is converted back into pressure energy. The washing liquid is introduced just in front of or in the throat and is atomized into small droplets by the high gas velocity. The exchange of substances takes place at the phase interface between droplets and gas. The dust-laden droplets can be separated with simple mechanical aids. Venturi scrubbers are often followed by centrifugal separators for separating droplets .

The processes known under the names Injektor-Venturi, Imatra-Venturi and Pease-Anthony-Venturi differ essentially in the way in which the detergent is introduced. Annular gap scrubbers are also among the Venturi scrubbers.

The flow velocities in the contact zone of Venturi scrubbers are usually between 80  m / s and 150 m / s, but gas velocities of up to 250 m / s can also be achieved. The pressure loss is between 3000  Pa and 20000 Pa. The main advantage of the Venturi scrubber is the ability to separate particles with a diameter of 0.5 µm to more than 99%. Its compact design is also a notable advantage. A disadvantage is the high energy consumption caused by the pressure loss. Another disadvantage is the design-related low flexibility of Venturi scrubbers with regard to the gas volume flow. This is counteracted constructively with adjustable throats.

commitment

Venturi scrubbers are usually used for the joint separation of gaseous and particulate impurities. They can also be used for oxidizing gas scrubbing .

The Venturi scrubber is the standard technology for exhaust air purification ( paint separation ) in the series painting of automobile bodies . More than 99% of the particles are separated, volatile organic compounds (VOC) up to their respective solubility limit. A sludge containing paint is continuously drawn off from the water used in the circuit. As the cleaned exhaust air is saturated with water vapor, fresh water must be added to the water cycle.

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. ↑ W. Muhlrad: About the precipitation of dust on a wet path with the help of Venturi tubes. In dust. No. 30, 1952, pp. 221-234.
  2. ↑ a b c Hans Güntheroth: Venturi scrubber for the separation of smoke, mist and aerosols. In: Dust: magazine for dust hygiene, dust technology, keeping the air clean, radioactive suspended matter . 21, No. 9, 1961, pp. 430-434.
  3. ^ A b Karl Georg Schmidt: Wet washing devices from the point of view of the operating man. In: Dust: magazine for dust hygiene, dust technology, keeping the air clean, radioactive suspended matter. 24, No. 11, 1964, pp. 485-491.
  4. ^ A b Günter Baumbach: Air pollution control. 2nd edition, Springer, Berlin / Heidelberg / New York 1992, ISBN 3-540-55078-X , p. 325.
  5. ^ Wilhelm Batel: Entstaubungstechnik - Fundamentals, procedures, measuring systems. Springer, Berlin 1972, ISBN 3-540-05649-1 , p. 113.
  6. ↑ a b c 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. 40.
  7. ↑ VDI 3679 sheet 4: 2014-10 wet separator; Waste gas cleaning by oxidative gas scrubbing (wet separators). Beuth Verlag, Berlin, p. 9.
  8. ↑ a b c VDI 3455: 2013-08 emission reduction; Systems for series painting of automobile bodies (emission control; high-volume car body painting plants). Beuth Verlag, Berlin, p. 75.
  9. ↑ VDI 3455: 2013-08 emission reduction; Systems for series painting of automobile bodies (emission control; high-volume car body painting plants). Beuth Verlag, Berlin, p. 76.