ANALYSIS ON SCALE FORMATION IN TREATMENT AND REUSE SYSTEM FOR COAL GASIFICATION ASH-CONTAINING WATER
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摘要: 煤气化过程中产生的灰水具有高温、高硬度、高氨和高悬浮物等特点,使现有预处理设施和回用系统的结垢与堵塞现象较为严重。为探明其结垢成因,在调研处理设施的基础上,研究了煤气化装置的灰水处理与回用管道、设施等的垢形物组成与结构。结果表明:灰水预处理与回用管道和设施的垢样形貌多样,呈块状、线状、管状、球状和花瓣状等,由Si、Ca、Mg、B、Al、Fe、S、Na、Mn、Ba等元素组成复杂化合物,以CaCO3、Al2O3·SiO2、MgCO3·3H2O、CaSiO3、K2O·Na2O·Al2O3·SiO2·H2O、Fe2O3、CaSO4、CaO·Al2O3·2SiO2、Ca4Mg[B4O6(OH)6](CO3)2、SiO2等形式存在。高温条件下钙镁硬度等引起的管壁沉积及其他元素的化合物共沉淀、灰水残余煤灰颗粒黏附管壁和设施底部等是成垢的主要原因;提升黑水和灰水的预处理效果,尤其是强化高温条件下的多种金属和非金属离子的同步去除效率是延缓灰水系统结垢的关键。Abstract: The wastewater produced in the process of coal gasification is characterized by high values in temperature, hardness, ammonia and suspended solids, so the existing pretreatment facilities and reuse systems are severely scaled and clogged. In order to find out the cause of scale formation, based on the investigation of the operation of the treatment facilities, the composition and structure of scaling substance in ash-containing water treatment and recycling pipes and facilities of coal gasification units were studied. The result indicated that the scale morphology of ash-containing water pretreatment and reuse pipes and facilities was diverse, shaped in blocks, lines, tubes, balls and petals, which were complex compounds composed of silicon, calcium, magnesium, boron, aluminum, iron, sulfur, sodium, manganese, barium and other elements, and its main components were CaCO3, Al2O3·SiO2, MgCO3·3H2O, CaSiO3, K2O·Na2O·Al2O3·SiO2·H2O, Fe2O3, CaSO4, Ca4Mg[B4O6(OH)6](CO3)2, SiO2, etc. The main causes of scale formation were tube wall deposition caused by calcium and magnesium hardness at high temperatures, compound co-precipitation of other elements, and residual ash particles adhering to the tube wall and bottom of facilities. Improving the pretreatment effect of black water and ash-containing water, especially enhancing the simultaneous removal efficiency of various metal and nonmetal ions at high temperature were the key to delaying the scaling of the ash-containing water treatment and reuse system.
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Key words:
- coal gasification /
- scale /
- morphology and composition /
- scale formation
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