OPACITY MEASUREMENT / PENGUKURAN KEGELAPAN

HISTORY OF OPACITY

The history of air pollution regulation dates back as far as the 13th century. In 1273 , Edward I (Lon gshanks) of England prohibited the burning o f sea coal, in London. The smoke produced by its combustion was considere d detrimental to human health. In 1307, a local blacksmith was convicted, condemned, and executed for this offense.The ad verse effects of air pollution increased with subsequent industrial development and urban population increases. Most early U.S. and English case law concerning air pollution fell under a part of the law commonly referred to as nuisance law. In the absence of specific regulations or laws against air pollutants, someone wanting to stop pollution (e.g., smoke from factories) had to bring a tort (or injury) case against the offender. Smoke was not generally considered a nuisance . Each case had to stand on its own merit and prove that the smoke in question was a nuisance. Eventually, communities passed regulations that sought to control air pollution. Court records from the late 19th and early 20th centuries contain many examples of city and state prosecutions of smoke ordinance violations. One of the earliest U.S. cases to uphold a municipal smoke control ordinance was the case of City of  New Orleans v. Lambert. The case involved another blac ksmith shop that, in violation of a city ordinance, emitted offensive odors and smoke, and was a nuisance.

RINGELMANN

The opacity evaluation system we use today evolved from a concept developed by Maximillian Ringelmann in the late 1800's. Ringelmann, an engineer working in France, developed a method to quantify emissions according to the visual density of the observed smoke. Ringelmann realized that the amount of dense black smoke from coal fired boilers was determined by combustion efficiency. Darker smoke meant poorer efficiency. Ringelmann developed a series of charts with graduated black grids on white backgrounds. When he placed the charts approximately 100 feet away, the grids appeared as shades of grey. Ringelmann was able to quantify emissions by comparing the shade of the smoke with the corresponding shade on his charts. By applying this information and adjusting the fuel/air ratio of a furnace, he could increase efficiency and decrease smoke. The Ringelmann Chart was adopted and promoted by the U .S. Bureau of Mines in the early 1900's in its efforts to improve coal combustion practices. It has since been used exten sively to assess and control emissions.

Experiences that I've installed  Opacity Monitor from Green Instrument Denmark. Installation of opacity monitor at DN1600 ducting leading to the chimney. Opacity Monitor  continously monitoring the residual gas in the process of sulfuric acid.

Opacity is caused by the absorption and scattering of light. Droplets and smaller particulate matters predominantly scatter the light. Larger soot and dust particles are predominantly causing absorption.

Opacity Monitor uses a high-power infrared light-beam. It is a single pass system where the beam of light is transmitted from the transmitter’s optical fiber across the duct or funnel to the receiver’s optical fiber. The optical transceiver is placed in the monitoring unit. The beam is absorbed and scattered by the smoke, mist, dust and vapor and thus the amount of light received by the transceiver is reduced. The monitoring unit displays the opacity. It indicates 0% if there is no opacity and 100% if the light beam is totally blocked. The alarms will activate if the opacity exceeds the preset limits.