Coal Slurry Drying Process Research

Abstract

Heavy stocks of high-moisture coal slurries being kept on the territory of Russia should be dried prior to recycling combustion in a TTP’s pulverized coal-fired boilers. The expediency and applicability of coal slurry drying in panel steam dryers (PSD), currently manufactured by JSC Tyazhmash, is shown. The results of laboratory and bench studies of coal slurry drying with a moisture content of 22–28%, ash content of 11%, lower calorific value of 17.8 MJ/kg, and particle sizes of not more than 0.3 mm are presented. The coal slurry drying rate-versus-temperature relationship is determined in a laboratory setting. The influence of PSD drum speed, its filling degree, and water-steam mixture (WSM) (heating medium) temperature on the moisture removal rate (MRR) is examined on a specially designed test bench. It is established that the WSM temperature is insignificant with respect to the MRR, which, however, increases by approximately 1.5–2.0 times with an increase in the drum rotation. The drying rate is equal to 0.127–0.969%/min, which is 2.4–7.8 times lower than the values obtained in a laboratory setting. The MRR is determined at the level of 10 kg/(m² h), which should be taken into account in the PSD design for coal slurry drying. To ensure the PSD capacity of 75 t/h, the drum filling degree should be 0.20–0.35, the drum angle 1°, the rotation speed 6.3–9.1 min^–1, the saturated steam rate 22.5 t/h, and the rate of the drying and aerating agent at a temperature of 100°C should be approximately 12000 m³/h. Basic PSD design characteristics for the capacity of 50 and 75 t/h are given.