Abstract This paper has addressed the techno-economic feasibility regarding the selective removal of sodium (Na) and calcium (Ca) from low-rank sub-bituminous coal, aiming to reduce the ash slagging and fouling propensity in the pulverized coal-fired boilers. Four novel process integrations were proposed and simulated in Aspen Plus. Both the novel counter-current three-stage water washing process and an acid-water two-stage washing process have proven to improve the ash fusion temperature satisfactorily, reducing the mass fraction of Na 2 O in ash from 4.32 wt% to 0.85 and 0.19 wt%, respectively. In addition, the use of acid-water washing removed 12.5% CaO and 19.5 wt% total ash. For the recycle and treatment of wastewater, the water gain is desirable for the use of an evaporator, owing to the dewatering of the initially high-moisture coal (25 wt%) in the centrifugal and the high water recovery rate from the evaporator. However, the good performance of evaporator was counteracted by the considerable capital cost caused by the huge heat transfer area requirement. Instead, the use of reverse osmosis (RO) resulted in a water loss up to 228.4 kg/t coal. Additionally, prior to the RO treatment unit, the recycle and reuse of the unsaturated water for maximum six times and four times for three-stage water washing and acid-water two-stage washing, respectively, was critical in reducing both the water and power consumption. The water consumption dropped to 38.1 kg/t coal and 48.1 kg/t coal for the three-stage water washing and acid-water two-stage washing process, respectively. Both are remarkably lower than 85.0 kg-water/t black coal. In terms of the power consumption, it decreased to ~ 9.4 kWh/t coal for the three-stage water washing process and further down to 5.8 kWh/t for the acid-water washing case, which was even slightly lower than 6.3 kWh/t for the black coal. Furthermore, the integration of acid-water washing and RO was also demonstrated to be economically viable by its high NPV, IRR and short payback period. Sensitivity analysis indicate that, the original Na content in raw coal is the most influential variable on the water and power consumption of the overall process, followed by the initial moisture content in the raw coal. For a low-rank coal containing > 2150–2520 ppm Na and/or

中文翻译：

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从低阶煤中选择性去除钠和钙——工艺集成、模拟和技术经济评价

摘要 本文探讨了从低阶次烟煤中选择性去除钠（Na）和钙（Ca）的技术经济可行性，旨在减少粉煤锅炉的灰渣结垢和结垢倾向。在 Aspen Plus 中提出并模拟了四种新颖的工艺集成。新的逆流三级水洗工艺和酸水两级洗涤工艺均已证明能令人满意地提高灰熔融温度，将灰中 Na 2 O 的质量分数从 4.32 wt% 降低到 0.85 和 0.19重量％，分别。此外，使用酸水洗涤去除了 12.5% 的 CaO 和 19.5% 的总灰分。对于废水的回收和处理，利用蒸发器的水增益是可取的，由于最初的高水分煤 (25 wt%) 在离心机中脱水和蒸发器的高水回收率。然而，蒸发器的良好性能被巨大的传热面积要求导致的可观资本成本抵消了。相反，反渗透 (RO) 的使用导致水分损失高达 228.4 kg/t 煤。此外，在RO处理装置之前，不饱和水最多回收再利用6次，三级水洗和酸水两级洗涤分别最多4次，是节水节电的关键。消费。三段水洗和酸水两段洗工艺用水量分别下降到38.1公斤/吨煤和48.1公斤/吨煤。两者都明显低于85。0公斤水/吨黑煤。在电耗方面，三段水洗工艺降低至约9.4千瓦时/吨煤，酸水洗工艺进一步降低至5.8千瓦时/吨，甚至略低于6.3千瓦时/吨对于黑煤。此外，酸水洗和反渗透的整合也被证明具有高 NPV、IRR 和短投资回收期的经济可行性。敏感性分析表明，原煤中原始Na含量是对整个过程水耗和电耗影响最大的变量，其次是原煤中的初始含水量。对于含有 > 2150–2520 ppm Na 和/或 酸水洗情况为8 kWh/t，甚至略低于黑煤的6.3 kWh/t。此外，酸水洗和反渗透的整合也被证明具有高 NPV、IRR 和短投资回收期的经济可行性。敏感性分析表明，原煤中原始Na含量是对整个过程水耗和电耗影响最大的变量，其次是原煤中的初始含水量。对于含有 > 2150–2520 ppm Na 和/或 酸水洗情况为8 kWh/t，甚至略低于黑煤的6.3 kWh/t。此外，酸水洗和反渗透的整合也被证明具有高 NPV、IRR 和短投资回收期的经济可行性。敏感性分析表明，原煤中原始Na含量是对整个过程水耗和电耗影响最大的变量，其次是原煤中的初始含水量。对于含有 > 2150–2520 ppm Na 和/或 对整个过程的水耗和电耗影响最大的变量是原煤中的原始 Na 含量，其次是原煤中的初始含水量。对于含有 > 2150–2520 ppm Na 和/或 原煤中的原始 Na 含量是对整个过程的水耗和电耗影响最大的变量，其次是原煤中的初始水分含量。对于含有 > 2150–2520 ppm Na 和/或