Liquid-to-gas ratio

Liquid-to-gas ratio

An important parameter in wet scrubbing systems is the rate of liquid flow. It is common in wet scrubber terminology to express the liquid flow as a function of the gas flow rate that is being treated. This is commonly called the liquid-to-gas ratio (L/G) and uses the units of gallons per 1,000 actual cubic feet or liters/cubic meter.

Expressing the amount of liquid used as a ratio enables systems of different sizes to be readily compared.For particulate removal, the liquid-to-gas ratio is a function of the mechanical design of the system; while for gas absorption this ratio gives an indication of the difficulty of removing a pollutant. Most wet scrubbers used for particulate control operate with liquid-to-gas ratios in the range of 4 to 20 gallons per 1,000 actual ft3 (0.5 to 3 liters per actual m3).

Dependending on scrubber design, a minimum volume of liquid is required to "wet" the scrubber internals and create sufficient collection targets. After a certain optimum point, adding excess liquid to a particulate wet scrubber does not help increase efficiency and in fact, could be counter productive by causing excessive pressure loss. Liquid-to-gas ratios for gas absorption are often higher; in the range of 20 to 40 gallons per 1,000 actual ft3 (3 to 6 litres per actual m3).

L/G ratio illustrates a number of points about the choice of wet scrubbers used for gas absorption. For example, because flue gas desulfurization systems must deal with heavy particulate loadings, open, simple designs (such as venturi, spray chamber and moving bed) are used.Also, the liquid-to-gas ratio for the absorption process is higher than for particle removal and gas velocities are kept low to enhance the absorption process.

Solubility is a very important factor affecting the amount of a pollutant that can be absorbed. Solubility governs the amount of liquid required (liquid-to-gas ratio) and the necessary contact time. More soluble gases require less liquid. Also, more soluble gases will be absorbed faster. [* [http://www.epa.gov/apti/ US EPA Air Pollution Training Institute] developed in collaboration with North Carolina State University, College of Engineering (NCSU)]

Bibliography

*Bethea, R. M. 1978. Air Pollution Control Technology. New York: Van Nostrand Reinhold.
*National Asphalt Pavement Association. 1978. The Maintenance and Operation of Exhaust Systems in the Hot Mix Batch Plant. 2nd ed. Information Series 52.
*Perry, J. H. (Ed.). 1973. Chemical Engineers’ Handbook. 5th ed. New York: McGraw-Hill.
*Richards, J. R. 1995. Control of Particulate Emissions (APTI Course 413). U.S. Environmental Protection Agency.
*Richards, J. R. 1995. Control of Gaseous Emissions. (APTI Course 415). U.S. Environmental Protection Agency.
*Schifftner, K. C. 1979, April. Venturi scrubber operation and maintenance. Paper presented at the U.S. EPA Environmental Research Information Center. Atlanta, GA.
*Semrau, K. T. 1977. Practical process design of particulate scrubbers. Chemical Engineering. 84:87-91.
*U.S. Environmental Protection Agency. 1982, September. Control Techniques for Particulate Emissions from Stationary Sources. Vol. 1. EPA 450/3-81-005a.
*Wechselblatt, P. M. 1975. Wet scrubbers (particulates). In F. L. Cross and H. E. Hesketh (Eds.), Handbook for the Operation and Maintenance of Air Pollution Control Equipment. Westport: Technomic Publishing.

References


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • Liquid nitrogen — (liquid density at the triple point is 0.707 g/mL) is the liquid produced industrially in large quantities by fractional distillation of liquid air and is often referred to by the abbreviation, LN2. It is pure nitrogen, in a liquid state. Liquid… …   Wikipedia

  • gas — gasless, adj. /gas/, n., pl. gases, v., gassed, gassing. n. 1. Physics. a substance possessing perfect molecular mobility and the property of indefinite expansion, as opposed to a solid or liquid. 2. any such fluid or mixture of fluids. 3. any… …   Universalium

  • Gas chromatography-mass spectrometry — (GC MS) is a method that combines the features of gas liquid chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC MS include drug detection, fire investigation, environmental analysis,… …   Wikipedia

  • Liquid-liquid extraction — Liquid liquid extraction, also known as solvent extraction and partitioning, is a method to separate compounds based on their relative solubilities in two different immiscible liquids, usually water and an organic solvent. It is an of a substance …   Wikipedia

  • Gas chromatography — A gas chromatograph with a headspace sampler Acronym GLC, GC Classification chromatography Analytes organic inorganic …   Wikipedia

  • Liquid fuels — are those combustible or energy generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. Most liquid fuels, in widespread use, are or derived from… …   Wikipedia

  • Gas core reactor rocket — Gas core reactor rockets are a conceptual type of rocket that is propelled by the exhausted coolant of a gaseous fission reactor. The nuclear fission reactor core may be either a gas or plasma. They may be capable of creating specific impulses of …   Wikipedia

  • Gas to liquids — (GTL) is a refinery process to convert natural gas or other gaseous hydrocarbons into longer chain hydrocarbons such as gasoline or diesel fuel. Methane rich gases are converted into liquid synthetic fuels either via direct conversion or via… …   Wikipedia

  • Gas — This article is about the physical properties of gas as a state of matter. For the uses of gases, and other meanings, see Gas (disambiguation). Ga …   Wikipedia

  • Gas compressor — A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”