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A novel combustion system was applied to a 600 MWe Foster Wheeler (FW) down-fired pulverized-coal utility boiler to solve high NOx emissions, without causing an obvious increase in the carbon content of fly ash. The unit included moving fuel-lean nozzles from the arches to the front/rear walls and rearranging staged air as well as introducing separated overfire air (SOFA). Numerical simulations were carried out under the original and novel combustion systems to evaluate the performance of combustion and NOx emissions in the furnace. The simulated results were found to be in good agreement with the in situ measurements. The novel combustion system enlarged the recirculation zones below the arches, thereby strengthening the combustion stability considerably. The coal/air downward penetration depth was markedly extended, and the pulverized-coal travel path in the lower furnace significantly increased, which contributed to the burnout degree. The introduction of SOFA resulted in a low-oxygen and strong-reducing atmosphere in the lower furnace region to reduce NOx emissions evidently. The industrial measurements showed that NOx emissions at full load decreased significantly by 50%, from 1501 mg/m3 (O2 at 6%) to 751 mg/m3 (O2 at 6%). The carbon content in the fly ash increased only slightly, from 4.13 to 4.30%.

Filtration membranes, with good antifouling performance and robust solvent resistance (e.g., organic solvents or highly acidic/alkaline/saline solvents), that can effectively purify complex polluted water systems are especially demanded in practice but present a challenge to be conquered. Herein, a simple method has been demonstrated to address the obstacles, applying the stabilized polyacrylonitrile (SPAN) nanofiber/β-FeOOH nanorod composite membrane as a model. In this work, simply stabilizing PAN nanofibers in air can achieve robust solvent resistance against organic solvents and strong inorganic acidic/alkaline/saline solutions. Hydrophilic β-FeOOH nanorods were anchored onto SPAN nanofibers of our electrospun membrane and achieve superhydrophilicity (0°)/underwater superoleophobicity (>155°) for various oils. More importantly, the SPAN/β-FeOOH nanofibrous membrane exhibits robust mechanical strength (274 MPa of Young’s modulus), excellent chemical stability, fast separation flux (2532–10146 L m–2 h–1), and satisfying removal ratio (>98.2%) against insoluble oils and soluble cationic dyes. In addition, good photocatalytic activity against organic pollutants provides our membranes with excellent flux restorability and a long-term use capacity. These outstanding performances endow our membrane with a great potential application in purifying polluted aquatic systems in worldly harsh conditions.

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