Characteristics of O₃ Oxidation for Simultaneous Desulfurization and Denitration with Limestone–Gypsum Wet Scrubbing: Application in a Carbon Black Drying Kiln Furnace

Abstract

The special process for producing carbon black precludes the application of traditional, mature flue-gas treatments (e.g., SNCR and SCR) to reduce NO x emissions. However, simultaneous removal of sulfur and nitrogen by the combination of ozone oxidation with limestone−gypsum wet scrubbing is suitable for the conditions found in carbon black flue gas. This article presents the first industrial-scale deployment of this technology in a 100000 t/year carbon black production line (flue-gas volume of 60000 Nm 3 /h). Optimizations were performed by studying the effectiveness of desulfurization and denitration for various operating parameters such as O 3 /NO x molar ratio, spray-tower liquid/gas ratio, initial NO x concentration, and forced oxidation. The results showed that (1) the O 3 /NO x molar ratio is the determining factor in denitration efficiency, (2) both forced oxidation and increasing initial NO x concentration improve the denitration efficiency but reduce the desulfurization efficiency, and (3) increasing the liquid/gas ratio can improve the desulfurization efficiency but has little effect on denitration. The maximum desulfurization and denitration efficiencies of the system can be up to 98% and 95%, respectively, with SO 2 and NO x levels of 1000 mg/Nm 3 (6% O 2 ) and 900 mg/Nm 3 (6% O 2 ) dropping to 20 mg/Nm 3 (6% O 2 ) and 45 mg/Nm 3 (6% O 2 ), respectively.

Simultaneous removal of SO2 and NOx by a new combined spray-and-scattered-bubble technology based on preozonation: From lab scale to pilot scale

“…(9)-(10) [31], [32]. However, according to the results of Ma et al [30], the increase of liquid/gas ratio decreases the sulfite concentration on the droplet surface, which weakens the reaction between NO 2 and sulfite to some extent, thereby decreasing the removal efficiency of NOx. Hence, the removal efficiency of NOx levels off above a certain liquid/gas ratio.…”

“…At the same time, the reaction between NOx and water is much faster than SO 2 and water, so that the removal efficiency of NOx is more sensitive than SO 2 to immersion depth [30].…”

“…The reaction between N 2 O 5 and water, as shown by Eq. (8) is fast, resulting in a stable removal efficiency for NOx[30].…”

Applicability of V2O5-WO3/TiO2 Catalysts for the SCR Denitrification of Alumina Calcining Flue Gas

“…Nitrogen oxide (NO x ), one of the main precursors of photochemical smog and haze pollution, causes great harm to the ecosystem and human lives [1,2]. Many strategies have been developed for NO x abatements from the stationary emission sources, including selective catalytic reduction (SCR) [3,4], selective non-catalytic reduction (SNCR) [5,6], activated carbon denitration [7,8], and oxidation-absorption method [9,10]. Among those methods, SCR technology has attracted extensive attention for being the most efficient strategy for NO removal [11].…”

Efficient and stable catalyst of α-FeOOH for NO oxidation from coke oven flue gas by the catalytic decomposition of gaseous H2O2

“…1 However, in traditional chemical industries, for example, coke oven ue gas yielded by coke oven gas combustion has a ue gas temperature of about 200-230 C and the composition is complex, 2 which limits the utilisation of SCR. 3 Recently, we proposed a promising process of gas-phase oxidation combined with wet scrubbing using steel slag slurry to treat NO x from low-temperature ue gas. 4,5 In this process, the sparingly soluble NO could be oxidised into soluble NO 2 , HNO 3 or N 2 O 5 through the gas-phase oxidation process, and then the oxidation products could be absorbed together with SO 2 in a wet scrubbing device.…”