ABSTRACT

Wet flue gas desulfurization (WFGD), using limestone with forced oxidation (LSFO), is a common Flue gas desulfurization (FGD) process where limestone reacts with SO₂ to produce gypsum (CaSO₄.2H₂O). In South Africa, Eskom’s Kusile Power Station utilizes conventional wet ball milling to grind high-grade limestone (96% CaCO₃) to 95% passing 45 µm prior to use in the FGD scrubber. For future FGD installations under consideration, the high energy cost associated with ball milling, particularly when pursuing fine grinding, has become a crucial factor raising the need for a quest for alternative milling technology to reduce the costs. The vertical roller mill (VRM) which has gained wide acceptance in the cement industry and is used for grinding raw materials (mainly limestone), is a promising alternative. The VRM dries, grinds, and classifies ores and minerals within a single unit. A pilot-scale Loesche VRM was used to determine the power required to grind 100 t/h of the same limestone as used at Kusile (work index of 12 kWh/t) with a top size of 19 mm to a 85% and 95% passing 45 µm product. A significant power saving of 39.2% was observed for the dry VRM compared to the wet ball mill (37.7% for the circuit). The capital investment for the dry Loesche VRM circuit was found to be 10.5% more expensive than that of a wet milling circuit, while the reduced power consumption combined with the decrease in grinding media and wear component consumption resulted in a 5.9% reduction in the operating expenditure (OPEX). The viability of the VRM in this application would also enable off-site dry milling of limestone, presenting significant potential capital and operating cost benefits for a power plant.

摘要

湿法烟气脱硫 (WFGD) 采用石灰石强制氧化 (LSFO)，是一种常见的烟气脱硫 (FGD) 工艺，石灰石与 SO ₂反应生成石膏 (CaSO ₄ .2H ₂ O)。在南非，Eskom 的 Kusile 发电站利用传统的湿式球磨机来研磨高品位石灰石（96% CaCO ₃) 至 95% 在用于 FGD 洗涤器之前通过 45 µm。对于正在考虑的未来 FGD 装置，与球磨相关的高能源成本，特别是在追求精细研磨时，已成为一个关键因素，需要寻求替代研磨技术以降低成本。立式辊磨机（VRM）在水泥行业得到广泛认可，用于粉磨原材料（主要是石灰石），是一种很有前景的替代品。VRM 在一个单元内对矿石和矿物进行干燥、研磨和分类。中试规模的 Loesche VRM 用于确定研磨 100 吨/小时与 Kusile 使用的相同石灰石（工作指数为 12 千瓦时/吨）所需的功率，顶部尺寸为 19 毫米至 85% 和 95%通过 45 µm 产品。显着节电 39。与湿式球磨机相比，干式 VRM 为 2%（回路为 37.7%）。发现干式 Loesche VRM 回路的资本投资比湿式研磨回路贵 10.5%，而功耗的降低以及研磨介质和磨损部件消耗的减少导致运行成本降低 5.9%支出（OPEX）。VRM 在该应用中的可行性还可以实现石灰石的异地干磨，从而为发电厂带来显着的潜在资本和运营成本效益。而功耗的降低与研磨介质和磨损部件消耗的减少相结合，使运营支出 (OPEX) 降低了 5.9%。VRM 在该应用中的可行性还可以实现石灰石的异地干磨，从而为发电厂带来显着的潜在资本和运营成本效益。而功耗的降低与研磨介质和磨损部件消耗的减少相结合，使运营支出 (OPEX) 降低了 5.9%。VRM 在该应用中的可行性还可以实现石灰石的异地干磨，从而为发电厂带来显着的潜在资本和运营成本效益。