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Monitoring Ambient Air

(Sulphur Dioxide)

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SO2

highly reactivegasses

Source fossil fuel combustion at power plants

other industrial facilities fertiliser manufacturing, aluminium smelting and steel making

coal and oil (for example, coal being burnt in a home fireplace for heating and diesel-powered vehicles).

Natural sources - geothermal activity

One of thecriteriapollutants

as theindicatorgaseous sulfuroxides (SOx).

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Effects

5minutes

- 24

hours

adverserespiratory

high concentrations ofSO2formation of other SOx

SOx can reactwith other

compounds

penetratedeeply into

sensitive parts

of the lungsand can causeor worsenrespiratory

disease, suchas

ecosystems

acid rain affect

vegetationaroundindustrial

dischargesand in cities

visibility

Hazereduce

visibility.

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MAIN COMPONENTS OF UVANALYZER

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Pneumaticsystem

sample inletline

particulate filter

hydrocarbon

scrubber/kicker dryer (if

needed)

sample cell

reactionchamber

flowmeter

pump

Analyticalsystem

UV source withthe associatedsource filters,lenses, and

optics light baffles

detector(photomultipliertube)

bandpassfilters.

Electronichardware

consists of theelectroniccomponentsthat control the

analyzer andprocess thesignals.

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UV SAMPLER COMPONENTS

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Instrumentshelter

Calibrationsystem

Data

acquisitionsystem(DAS)

Wiring,

tubing &fittings

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OPERATING PRINCIPLE

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Measures emitted fluorescence of SO2produced by theabsorption of uv light

Narrow band-pass filter mirror allows only light wavelengthsof 190 to 230 nm to pass into the fluorescent chamber

The SO2molecules absorbed are excited by UV light andemit a characteristic decay radiation

A second filter allows only this decay radiation to contact aphotomultiplier tube (PMT). Electronic signal processingtransfers the light energy impinging on the PMT into a voltage

which is directly analyzed

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SO2 +h1 SO2 *SO2 +h2 where:

Where h1 = incidence light,

h2 = fluoresced light

SO2* = SO2 in its excited state

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METHODS FOR UV SAMPLER

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In sample mode, the sample isdrawn into the analyzer through the

sample bulkhead.

The sample flows through a

hydrocarbon kicker (scrubber) whichallows only hydrocarbon moleculesto pass through the tube wall.

The sample flows into thefluorescence chamber, wherepulsating UV light excites the SO2molecules.

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The band pass filter allows only thewavelengths emitted by the excitedSO2 molecules to reach the PMT. The

PMT detects the UV light emissionfrom the decaying SO2 molecules

The sample then flows through a flowsensor

Outputs the SO2concentration to thefront panel display and the analog ordigital outputs.