A  pilot-scale condensing waste heat exchanger

Pawel Raczka

Abstract


This paper presents a calculation algorithm, design assumptions and results of studies concerning a flue gas/water heat exchanger with the condensation of water vapor contained in flue gas from the combustion of brown coal. The algorithm was used for design calculations of a pilot-scale heat exchanger with capacity of 380/312 kW. A cross-counter flow heat exchanger with capacity of 312 kW and coils made of PFA (perfluoroalkoxy polymer) was designed and installed. Waste heat is recovered from flue gas produced by a pulverized brown coal fired subcritical steam boiler operated in a power unit with capacity of 370 MWe. The heat exchanger was theoretically divided into a noncondensing part (sensible heat recovery) and a part with the condensation of water vapor contained in flue gas (recovery of sensible and latent heat). The point of the division is the temperature of flue gas in the stream core (higher than near the pipe wall) where the condensation of water vapor occurs on the pipe surface. The heat transfer in the non-condensing part was calculated using the same formulas as for the economizer in a pulverized-fuel boiler, while the calculations of the heat and mass transfer in the condensing part were performed using the VDI algorithm. The results of the thermal calculations and the geometry of the heat exchanger together with the place of installation of the entire test rig are presented. The results of the calculation are then compared with the test results. Good correlation was achieved between the test results and the assumptions and results of the design calculations. Calculations for full scale exchanger for 370 MW brown coal fired power unit showed a 1.18% net efficiency increase with improving wet flue gas desulphurization process (EUR 3.7 million annual savings of fuel consumption and CO2 emission).

Keywords


condensing heat exchanger, waste heat, power boiler, chimney loss reduction, latent heat

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References


K. Jeong, M.J. Kessen, H. Bilirgen, E.K. Levy. Analytical modeling of water condensation in condensing heat exchanger. International Journal of Heat and Mass Transfer 53 (2010).Edit

Edward Levy, Harun Bilirgen, Kwangkook Jeong, Michael Kessen, Christopher Samuelson, Christopher Whitcombe. Recovery of Water from Boiler Flue Gas. Office of Scientific and Technical Information (OSTI), 2008. LinkEdit

P. Szulc, T. Tietze. Recovery and energy use of flue gas from a coal power plant. Journal of Power Technologies 97, 135-144 (2017).Edit

A. P. Colburn, O. A. Hougen. Design of Cooler Condensers for Mixtures of Vapors with Noncondensing Gases. Industrial & Engineering Chemistry 26, 1178–1182 American Chemical Society (ACS), 1934. LinkEdit

D.A. Ball, E.L. White, J.J. Lux, R. Razgaitis, R.A. Markle. Condensing heat exchanger systems for residential/commercial furnaces and boilers. Phase III. DOE Contract Number AC02-76CH00016 (1984).Edit

Masahiro Osakabe. Latent heat recovery from oxygen-combustion flue gas. 804-812 In 35th Intersociety Energy Conversion Engineering Conference and Exhibit. American Institute of Aeronautics and Astronautics, 2000. LinkEdit

L. Jia, X.F. Peng, Y. Yan, J.D. Sun, X.P. Li. Effects of water vapor condensation on the convection heat transfer of wet flue gas in a vertical tube. International Journal of Heat and Mass Transfer 44, 4257–4265 Elsevier BV, 2001. LinkEdit

Yongbin Liang, Defu Che, Yanbin Kang. Effect of vapor condensation on forced convection heat transfer of moistened gas. Heat and Mass Transfer 43, 677–686 Springer Science and Business Media LLC, 2007. LinkEdit

Xiaojun Shi, Defu Che, Brian Agnew, Jianmin Gao. An investigation of the performance of compact heat exchanger for latent heat recovery from exhaust flue gases. International Journal of Heat and Mass Transfer 54, 606–615 Elsevier BV, 2011. LinkEdit

Xiling Zhao, Lin Fu, Weixing Yuan, Feng Li, Qingsheng Li. The Potential and Approach of Flue Gas Waste Heat Utilization of Natural Gas for Space Heating. Procedia Engineering 146, 494–503 Elsevier BV, 2016. LinkEdit

P. Nobel, M. Vasconcelos, F. Tegnér, F.P. Serrano. Designing a Flue Gas Condenser System for Lomma Power Plant. KET050: Feasibility Studies on Industrial Plants. (2014).Edit

J. Milewski, W. Bujalski, M. Wolowicz, K. Futyma, J. Kucowski. Off-design operation of an 900 MW-class power plant with utilization of low temperature heat of flue gases. Journal of Power Technologies 95, 221-227 (2015).Edit

VDI Heat Atlas. Springer Berlin Heidelberg, 2010. LinkEdit

P. Rączka, K. Wójs. Methods of Thermal Calculations for a Condensing Waste-Heat Exchanger. Chemical and Process Engineering 35, 447–461 Walter de Gruyter GmbH, 2014. LinkEdit

А.А. Abriutin, E.S. Karasina et al. Teplovoi raschet kotlov - normativni metod. (Thermal calculations of power boilers). WTI/CKTI Sankt-Peterburg, 1998.Edit

P. Rączka. Poprawa sprawności cieplnej bloków energetycznych poprzez wykorzystanie odzyskanego ciepła odpadowego. Rynek Energii 122, 80-86 (2016).Edit


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