Particulate Matter
Particulate matter is at times referred to as ash. It is composed of inorganic materials (calcium, potassium, silica, sodium, aluminum, iron and magnesium), unconverted char and bed material (in case of fluidized bed gasifier). Elements such as arsenic, selenium, zinc, and lead are minor constituents of the particulate matter. The size, composition, and the concentration of the particulate matter depend on the type of gasifier and its operating condition such as temperature, gas velocity, moisture content in fuel, and rate of gasification. Table 10.1 shows the particulate matter in product gases from few different gasifiers.
The size of the particulate matter varies from less than 1 micron to larger then 100 microns. A typical syngas application requires higher then 99% removal of particulate matter (Woolcock and Brown, 2013). Besides posing health risk, particulate matters are also responsible for causing fouling, erosion, and corrosion of downstream equipment.
The particulate matter can be separated using various techniques depending on whether it is done at hot or cold conditions. The hot gas particulate matter separation can be achieved with cyclone separator or candle filter or electrostatic separator or a combination of them based on the level of separation needed. Particulate matter separation at cold condition is done through wet scrubbing.
