Particulate matter (PM) pollution from coal combustion is a leading contributor to the influence of atmospheric visibility, photochemical smog, and even global climate. A drop tube furnace was employed to explore the effects of temperature and chemical speciation of mineral elements on PM formation during the combustion of Zhundong coal. Chemical fractionation analysis (CFA), X-ray fluorescence (XRF), and inductively coupled plasma-atomic emission spectrometry (ICP-AES) were used to investigate the chemical and physical characteristics of the solid samples. It can be indicated that the combustion of similarly sized coal particles yielded more PM10 when the combustion temperature was increased from 1000 to 1400 °C. Zhundong coal is fractionated with deionized water, ammonium acetate, and hydrochloric acid, and pulverized coal, after fractionation, is burned to study the influence of mineral elements with different occurrence forms, such as water-soluble mineral elements, exchangeable ion elements, hydrochloric acid soluble elements and acid-insoluble elements, on the formation of particles. The results show that water-soluble salts play an important role in forming ultrafine particles (PM0.2); Fe, Ca, and other elements in organic form are distributed in flue gas through evaporation during pulverized coal combustion. When the flue gas temperature decreases, PM1 is formed through homogeneous nucleation and heterogeneous condensation, resulting in the distribution of these two elements on PM1. Different fractionation methods do not significantly affect the distribution of Si and Al in the PM1–10 combustion process.

The reduced atmospheric pressure and oxygen mass concentration at high altitudes have brought tremendous problems to the operation of gas‐fired boiler, mainly due to their influence on gas combustion and flow within furnace. Boilers designed for plateau region generally experience insufficient output, incomplete combustion, and reduced thermal efficiency when operating at high altitudes. However, the impacts from increasing altitude to the combustion characteristics within furnace are still ambiguous, which greatly hampers the boiler design for high‐altitude area. In this paper, the influences of altitude on the gas combustion characteristics within furnace were explored by using the computational fluid dynamics (CFD) method. The simulation shows that when altitude rises from 0 to 4000 m, the flame length and width increase as well as the temperature within furnace, but the burnout rate decreases due to the reduced residence time. The furnace length and diameter of the boiler designed for high altitudes should be appropriately increased to avoid the high temperature flame from scouring the back tube sheet and the furnace liner. While the CO emissions are generally very low, an increasing trend with altitude was observed. In addition, for each 1000 m of altitude rise, the NOx emissions increase by about 14 mg·m−3 at 100% loads and α = 1.05. The present work reveals the influence of altitude on combustion characteristics within gas‐fired boiler, which can guide the design and operation of the gas‐fired boiler at high altitudes.

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