385 / 2018-12-14 14:48:59

Investigations on Sodium and Potassium Capture characteristics in a 300MW Wet bottom Boiler

high alkali coal, wet bottom boiler, alkali metal, slag capture

全体主题 > 燃料利用与化学循环技术

The reserves of high alkali coal in Xinjiang is huge, but contents of alkali metals such as Na and K are relatively high in it, leading to characteristics of strong tendency to fouling and slagging. When burning with high alkali coal, problems such as overtemperature of the heating surface tube wall, tube explosion and flue gas duct blockage occur frequently, which seriously affect the safety and economy of boiler operation. Application of wet bottom boiler is an effective way to solve the problems such as fouling, ash accumulation and slagging when high alkali coal is combusted. One hand, slag tapping can improve the ash capture efficiency of boiler, thus greatly reducing the dust concentration of flue gas entering the downstream heating surface. On the other hand, physical-chemical interaction between high temperature liquid slag and alkali metals Na and K in coal can capture alkali metals in slag in the form of low melting point minerals. Na and K are discharged in slag from the bottom of the furnace, which reduces the concentration of Na and K in gas phase. The paper employed a 300MW wet bottom boiler as the research object, by gradually increasing the proportion of high alkali coal, slag and fly ash of different components were sampled and analyzed. The results showed that liquid slag can capture more than 50% of Na and K in high alkali coal, higher than that of solid ash and kaolin added in high temperature area, thus restraining the fouling and slagging of heating surface effectively.