School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry, University of Science and Technology Beijing, Beijing, 100083, China.
Environ Pollut. 2019 Mar;246:249-256. doi: 10.1016/j.envpol.2018.12.001. Epub 2018 Dec 2.
Aerosol particulate matter with dynamic diameter smaller than 2.5 μm (PM) is the main cause for haze pollution in China. As a dominant precursor of PM, SO emitted from industrial process is now strictly controlled by using limestone/gypsum Wet Flue Gas Desulfurization (WFGD) system in China. However, a phenomenon that fine particle derived from WFGD is recently addressed, and is suggested to be a potential source of primary PM. Herein, a first investigation into the particle generation mechanism in WFGD system is conducted with a novel droplet (containing particles) drying and breakage model. The proposed model considers a random and porous crust instead of the previous regular crust assumption, and is verified by comparing the modeling results with measurements. An orthogonal test with four factors and three levels is carried out through modeling calculation, and flue gas temperature (T) in the inlet is found to be a governing parameter for PM yields in WFGD. With T in range of 120-160 °C, PM yields in desulfurizing tower can reach a maximum value at ∼2 × 10 cm under typical WFGD condition. To avoid this situation and reduce the PM generation, T is suggested to be lower than 120 °C. Additionally, a new insight of the elimination effect of gas-gas heater (GGH) on "gypsum rain" in WFGD system is provided.
在中国，直径小于 2.5μm 的气溶胶颗粒物（PM）是雾霾污染的主要原因。作为 PM 的主要前体物，工业过程中排放的 SO 通过在中国使用石灰石/石膏湿法烟气脱硫（WFGD）系统得到了严格的控制。然而，最近人们关注到一个现象，即来自 WFGD 的细颗粒可能是初级 PM 的潜在来源。在此，通过建立一种新的液滴（包含颗粒）干燥和破裂模型，对 WFGD 系统中的颗粒生成机制进行了首次研究。所提出的模型考虑了随机多孔外壳，而不是之前的规则外壳假设，并通过将建模结果与测量结果进行比较进行了验证。通过建模计算进行了一个四因素三水平的正交试验，发现进入脱硫塔的烟气温度（T）是 WFGD 中 PM 产率的控制参数。在 120-160°C 的范围内，在典型的 WFGD 条件下，脱硫塔中的 PM 产率在 2×10cm 时达到最大值。为了避免这种情况并减少 PM 的生成，建议 T 低于 120°C。此外，还提供了对 WFGD 系统中气体-气体加热器（GGH）对“石膏雨”消除效果的新认识。
