• Applied Chemistry for Engineering
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• v.32 no.2
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• pp.149-156
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• 2021

A kraft recovery boiler produces steam for power generation by the combustion of black liquor from the kraft pulping process. Since saturated steam became superheated in a superheater above the furnace, it is important to increase the heat exchange efficiency for the superheated steam production and power generation. A nose arch at the bottom of the superheater is important for blocking radiation from the furnace which causes corrosion of the superheater. But the nose arch is the main reason for creating a recirculation region and then decreasing the heat exchange efficiency by holding cold flue gas after the heat transfer to saturated steam. In this study, the size of recirculation region and the temperature of flue gas at the outlet were analyzed by the nose arch structure using computational fluid dynamics (CFD). As a result, when the nose arch angle changed from 106.5° (case 1) to 150° (case4), the recirculation region of flue gas decreased and the heat exchange efficiency between the flue gas and the steam increased by 10.3%.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.499-505
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• 2022

This study presents a conceptual design of vanillin production from Kraft lignin. Most of the existing Kraft lignin is used as low-quality boiler fuel or discarded as wastewater, and only 2% or less of lignin has been refined into high-quality products. We propose the process developed in this study to utilize discarded Kraft lignin. The existing vanillin production concept process consisted of alkali oxidation using NaOH, filtration, chromatography, and crystallization. Chromatography, which is difficult to commercialize, was changed to a solvent extraction process. The recovery rate of vanillin of the proposed solvent extraction process is 92.9%, and the purity is 99.5%, which is similar to the existing chromatography process. The reason why the solvent extraction process showing similar results to chromatography can replace the existing chromatography process was analyzed.