CFD를 활용한 크래프트 회수보일러 내부 노즈 아치 구조에 따른 열교환 효율 분석

장용호; 박현도; 임경필; 박한신; 김정환; 조형태; Yongho Jang; Hyundo Park; Kyung pil Lim; Hansin Park; Junghwan Kim; Hyungtae Cho

Applied Chemistry for Engineering, Vol.32, No.2, 149-156, April, 2021

DOI10.14478/ace.2021.1007 Export Citation

CFD를 활용한 크래프트 회수보일러 내부 노즈 아치 구조에 따른 열교환 효율 분석

Analysis on the Heat Exchange Efficiency of Kraft Recovery Boiler by Nose Arch Structure Using CFD

장용호^{1, 2}, 박현도^{1, 3}, 임경필⁴, 박한신⁴, 김정환^{1, †}, 조형태^{1, †}

¹건국대학교 화학공학부
²건국대학교 화학공학부,
³연세대학교 화공생명공학과
⁴무림P&P(주) 프로젝트부

Yongho Jang^{1, 2}, Hyundo Park^{1, 3}, Kyung pil Lim⁴, Hansin Park⁴, Junghwan Kim^{1, †}, and Hyungtae Cho^{1, †}

¹Green Materials and Processes R&D Group, Korea Institute of Industrial Technology, Ulsan 44413, Korea
²Department of Chemical Engineering, Konkuk University, Seoul 05029, Korea
³Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 03722, Korea
⁴Project Part, MOORIM P&P Co., Ulsan 45011, Korea

E-mail:,

초록

크래프트 회수보일러(kraft recovery boiler)는 펄프 공정에서 생성된 흑액을 연소하여 발전용 스팀을 생산하는 장치이다. 특히 연소로 상단부에 존재하는 과열기(superheater)는 포화 증기가 연소가스와 열교환을 통해 과열 증기로 전환되는 구간으로, 연소가스와 포화 증기 사이의 열교환 효율 향상은 발전용 과열 증기 생산량 증가 및 발전 효율이 증가하므로 매우 중요하다. 과열기 하단부에 위치한 노즈 아치는 과열기의 부식의 원인이 되는 연소로에서 발생한 복사열을 막는 중요한 역할을 하지만, 연소가스 유동을 방해하여 포화증기와 열교환이 끝난 저온의 연소가스가 과열기를 나가지 못하고 재순환되어 열교환 효율을 저하시키는 직접적인 원인이 된다. 따라서 본 연구에서는 CFD를 활용하여 노즈아치 구조에 따른 재순환 영역의 크기와 연소가스 출구 온도를 비교하였다. 결과적으로 노즈 아치 하단부 각도를 106.5°에서 150°로 변경할 경우 연소가스의 재순환 영역이 감소하여 연소가스와 과열기 사이의 열교환 효율이 10.3% 향상되는 것을 확인하였다.

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%.

Keywords:Kraft recovery boiler;Nose arch (bullnose);Recirculation region;Superheater;Computational fluid dynamics (CFD)

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[3] Tejado A, Pena C, Labidi J, Echeverria JM, Mondragon I, Bioresour. Technol., 98(8), 1655 (2007)

[4] Cho JH, Journal of Korea TAPPI, 41, 13 (2009).

[5] Emami B, Numerical Simulation of Kraft Recovery Boiler Sootblower Jets, PhD Dissertation, University of Toronto, Toronto, Canada (2009).

[6] Hu J, Zhang Q, Lee DJ, Bioresource Technol., 247, 1181 (2018)

[7] Vakkilainen E, Kraft Recovery Boilers - Principles and Practice, Suomen Soodakattilayhdistys r.y., Helsinki, Finland (2005).

[8] Horton R, Grace T, Adams T, IPST Technical Paper Series, 435, 1(1992).

[9] Lundborg A, Simulation of the Flue Gas Flow through the Superheater in a Recovery Boiler, Stockholm, Sweden (2005).

[10] Tak K, Kim J, Comput. Chem. Eng., 117, 97 (2018)

[11] Kawaji M, Shen XH, Tran H, Esaki S, Dees C, TAPPI J., 78, 214 (1995)

[12] Holkar R, Ramdas B, Kunal E, Haridas B, J. Mech. Civil Eng., 11, 31 (2014)

[13] Granda M, Trojan M, Taler D, Energy, 199, 117423 (2020)

[14] Kumar K, Integrated Computational Fluid Dynamics and 1D Process Modelling for Superheater Region in Recovery Boiler, Finland (2019).

[15] Vakkilainen E, Horton R, Adams T, IPST Technical Paper Series, 436, 1 (1992)

[16] Maakala V, Jarvinen M, Vuorinen V, Appl. Therm. Eng., 139, 222 (2018)

[17] ANSYS Fluent User’s Guide, USA (2019).

[18] ANSYS Fluent Theory Guide, USA (2013).

[19] Cho H, Cha B, Kim S, Ryu J, Kim J, Moon I, Ind. Eng. Chem. Res., 52(22), 7252 (2013)

[20] Cho H, Kim J, Park C, Lee K, Kim M, Moon I, Powder Technol., 312, 113 (2017)

[21] Van Doormaal JP, Raithby GD, Numerical Heat Transfer, 7, 147 (1984)