Experimental Study on Ash Deposition Characteristics of High Sodium Coals from Xinjiang

The effects of flue gas and outer wall temperature on the ash deposition characteristics of heating surface tubes during the combustion of three different coals were experimentally investigated on a 3 MW pulverized-coal combustion test rig,including two high sodium coals from Xinjiang and one non-high-sodium coal.Results indicate that the flue gas and outer wall temperature can significantly impact the ash deposition characteristics of the test section,which is closely related to the melting point of all kinds of sodium compounds in flue gas.When the flue gas temperature is 520 ℃(lower than the lowest melting point of various sodium compounds in flue gas),the ratio of the heat transfer coefficient Rhalmost does not change with time,which is approximately equal to 1.When the flue gas temperature is higher than 650℃,the Rh of the test section reduces gradually with the extension of time,and the higher the flue gas temperature is,the faster the Rhfalls.