Wednesday, January 21, 2009

991 CEM - Continuous Emission Monitor

SO2 (sulfur dioxide) Continuous Emission Monitoring


so2 continuous emission monitoring

Continuous Emission Monitoring (CEM) Systems are mandatory on virtually all industry waste chimneys or stacks today. Depending on the industrial process and regulatory agency requirements, the CEM could be required to report the pollutant of interest on an oxygen (O2) free, dry basis or, on a mass basis (tons per day, pounds per hour). Galvanic Instrumentation Ltd. offers systems that comply with both requirements.

Instrumentation System

Because the O2 free basis system measures the pollutant on a dry basis, a sample dryer is incorporated in the sample system. The concentration of oxygen is also measured and the measured dry pollutant concentration is corrected to zero oxygen.

The mass emission system measures the pollutant concentration on an as-is (hot/wet) basis and incorporates gas stream velocity and temperature measurement devices. The volume flow rate of the effluent is determined along with the mass emission rate of the pollutant of interest.

Continuous Emission Monitoring

Galvanic’s CEM System features our ultraviolet (UV) fibre optic spectroscopy for the sulfur dioxide (SO2) analysis. Depending on the type of system specified, the analysis is performed on either a dry or hot/wet basis. For either one sample is transported from the sample point to the analyzer through a heated sample line (steam or electrical heating is available). The dry base system uses a chilled, water-condensing unit to remove the water from the stack gas sample.

The mass style of CEM system is complete with a velocity measuring device suitable for an accurate measurement of the gas velocity for a given chimney or stack. A variety of different measurement techniques and hardware devices (pitot tube, annubar, Kurz probe, etc.) are available and necessary since no one sensor is applicable for all ranges of velocities, temperatures, etc. Galvanic selects the appropriate device based on the engineering data for your application. The stack gas temperature measurement is achieved with a thermocouple selected and calibrated for your stack gas temperature range.

The stack gas volumetric flow rate is calculated by the system computer using the data from the velocity device, the gas temperature and other parameters including the stack diameter, specific gravity, profile factor, etc. The SO2 concentration and volume flow rate are combined and the mass emission rate for the SO2 is calculated and output in terms of either SO2 or sulfur. Outputs provided are the instantaneous values for SO2 concentration, volume flow rate and mass emission rate.