Читать книгу Continuous Emission Monitoring - James A. Jahnke - Страница 85

Moisture is usually removed before the hot flue gas enters a sample pump because water vapor and acid gases can easily condense in an unheated pump and corrode the interior. Cooling beyond the dew point (the temperature at which air is saturated with moisture) will cause moisture to condense, and many of moisture removal systems are designed to reduce the sample temperature below the dew point. Thermoelectric and compressor‐operated gas coolers are most commonly used for this purpose in extractive systems. Coolers should be correctly sized for the sample gas flow rates and stack‐gas moisture content; also, coolers must remove condensed water rapidly from the gas stream to minimize contact with dried gas.