AbstractWith the application of selective catalytic reduction (SCR) technology, the operation of rotary air preheaters is faced with a challenge, the fouling problem caused by ammonium bisulfate (ABS). Previously, some investigators experimentally studied the deposition characteristics of ABS. In their studies, the sediment composition initially formed in the experimental section is regarded as ABS without relevant tests. Within the operational temperature range of the preheater, the gaseous ammonia and sulfur trioxide (or H2SO4) in the flue gas can react to form ABS and ammonium sulfate (AS). Since AS has a slightly higher initial formation temperature&nbsp;&nbsp; than ABS [1-3]. the initial condensation temperature of ABS might be over predicted in previous studies due to the effect of the formation of AS. In this study, the effects of the deposition temperature, ammonia-sulfur molar ratio and molar product of inlet flue gas on the deposition characteristics of inducing ash deposition compounds were experimentally studied, so as to provide guidance to prevent fouling and corrosion of rotary air preheaters. The results show that the main path to generate ABS is the reaction between H2SO4 and NH3, and the transformation from SO2 to SO3 hardly occurs in the flue gas. With the increase in the deposition temperature, the contents of NH4+ and SO42- in the sediments decrease continuously, and the proportion of AS deposition increases. On the contrary, when the temperature decreases, more ABS is deposited in the sediments. When the molar ratio of ammo-sulfur in the inlet flue gas increases, the proportion of AS in the sediments increases, and the deposition rate also gradually increases. With the increase of the ammo-sulfur product in the inlet flue gas, the concentrations of both NH4+ and SO42- in the sediments gradually increased in a nearly consistent trend. The variations of the ratio and deposition rates of the two ions in the sediments were not obvious. The ratio of NH4+ and SO42- remains at about 1.2, and the sediment is mainly ABS.Key words：Rotary air preheater; Ammonium bisulfate; Deposition characteristics; Ash deposition and corrosionReferences:[1] Burke JM, Johnson KL. Ammonium sulfate and bisulfate formation in air preheaters[J]. Bmj BritishMedical Journal, 1982, 329: 446-457.[2] Ando J. NOx abatment for stationary sources in Japan-M[J]. Faculty of Science and Engineering, 1983, 83.[3] Limin Wang YB, Chunli Tang, Cheng Lv, Xun Chen, Defu Che. Study on the formation process of low‐temperature ash deposition induced by ammonium bisulfate in pulverized coal‐fired boiler[J]. Asia-Pacific Journal of Chemical Engineering, 2019, 15 (4).&nbsp;

Experimental Investigation of Ammonia and Sulfur Deposition Characteristics in Rotary Air Preheater

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ASME 2021 Power Conference (POWER2021)

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