The Effect of Fouling on the Baffle Spacing of a Shell and Tube Heat Exchanger

Abstract

In this study, shell-side fouling of the shell and tube heat exchanger (STHE) designed for a textile firm was examined. The economic baffle spacing was determined for clean and fouled conditions. The energy and pressure loss analysis was performed using Bell –Deleware method. To predict the fouling thickness (FT), a prototype tube bundle was installed in the chimney of the stenter machine to expose to the exhaust gases. The FT on tubes reached to about 0.5 mm within three months. Fuel saving (FS) due to recovered heat and fan power consumption (FPC) due to pressure drop were calculated by assuming that FT varies linearly with time. In the result of the cost analysis, it was seen that economic baffle spacing was affected by R value which is the ratio of unit cost of natural gas to that of electricity but the effect of fouling on the optimum baffle spacing was not significant. Fouling affected optimum baffle spacing when R is greater than 15. In this study optimum baffle spacing was determined as 1.16 m for both fouled and clean condition, because of that R is 3.52 in Turkey at the time of the study.

Keywords

• Heat exchanger
• Baffle spacing
• Fouling

Kirlenmenin Bir Gövde-Boru Isı Eşanjörünün Şaşırtma Levhası Aralığı Üzerindeki Etkisi

Abstract

Bu çalışmada, bir tekstil firması için tasarlanan gövde borulu ısı eşanjörünün gövde tarafındaki kirlenmenin etkileri incelenmiş, temiz ve kirli koşullar için ekonomik şaşırtma levhası aralığı belirlenmiştir. Enerji ve basınç kaybı analizi Bell-Deleware yöntemi kullanılarak yapılmıştır. Kirlenme kalınlığını tahmin etmek için, ramöz makinesinin bacasına egzoz gazlarına maruz kalması için bir prototip boru demeti yerleştirilmiş ve üç ay içinde borulardaki kirlenme kalınlığının yaklaşık 0.5 mm’ye ulaştığı görülmüştür. Hesaplarda, kirlenme kalınlığının zamanla doğrusal olarak değiştiği varsayılmıştır. Maliyet analizi sonucunda, ekonomik şaşırtma levhası aralığının, doğal gazın birim maliyetinin elektriğin birim maliyetine oranı olan R değerinden etkilendiği, ancak optimum şaşırtma levhası aralığı üzerinde kirlenmenin etkisinin önemli olmadığı görülmüştür. Kirlenme, R nin 15’den büyük olduğu durumlarda optimum şaşırtma levhası aralığını etkilemiştir. Çalışmanın yapıldığı zamanda Türkiye’de R değerinin 3.52 olması nedeniyle hem kirli hem de temiz durumda optimum şaşırtma levhası aralığı 1.16 m olarak belirlenmiştir.

Keywords

• Isı değiştiricisi
• Şaşırtma levhası aralığı
• Kirlenme

References

1. [1] Abdelkader, B. A., Zubair, S. M. 2019. The Effect of a Number of Baffles on the Performance of Shell and Tube Heat Exchangers. Heat Transfer Engineering, 40, 39-52.
2. [2] Soltan, B. K., Avval, M. S., Damangir, E. 2004. Minimizing Capital and Operating Costs of Sheel and Tube Condensers Using Optimum Baffle Spacing. Applied Thermal Engineering, 24, 2801-2810.
3. [3] Li, H., Kottke, V. 1998. Effect of Baffle Spacing on Pressure Drop and Local Heat Transfer in Shell and Tube Heat Exchangers for Staggered Tube Arrangement. Heat Mass Transfer, 41(10), 1303-1311.
4. [4] Eryener, D. 2006. Thermoeconomical Optimization of Baffle Spacing for Shell and Tube Heat Exchanger. Energy Conversion and Management, 47, 1478-1489.
5. [5] Jozaei, A. F., Baheri, A., Hafshejani, M. K., Arad, A. 2012. Optimization of Baffle Spacingon Heat Transfer Pressure Drop and Estimated Price in a Shell and Tube Heat Exchanger. World Applied Sciences Journal, 18(12), 1727-1736.
6. [6] Wang, F. L., He, Y. L., Tong, Z. X., Tang, S. Z. 2017. Real-time Fouling Characteristics of a Typical Heat Exchanger Used in the Waste Heat Recovery Systems. International Journal of Heat and Mass Transfer 104, 774–786.
7. [7] Wallhäußer, E., Hussein, M. A., Becker, T. 2012. Detection Methods of Fouling in Heat Exchangers in the Food Industry. Food Control, 27, 1-10.
8. [8] Kim, W., Cho, Y. I. 2011. Benefit of Filtration in Physical Water Treatment for the Mitigation of Mineral Fouling in Heat Exchangers. International Communications in Heat and Mass Transfer 38, 1008–1013.

9. [9] Markowski, M., Trafczynski, M., Urbaniec, K. 2013. Identification of the Influence of Fouling on the Heat Recovery in a Network of Shell and Tube Heat Exchangers. Applied Energy, 102, 755–764.
10. [10] Shen, C., Cirone, C., Yang, L., Jiang, Y.,Wang, X. 2014. Characteristics of Fouling Development in Shell- and - Tube Heat Exhanger: Effects of Velocity and Installation Location. International Journal of Heat and Mass Transfer 77, 439-448.
11. [11] Bouris, D., Papadakis, G., Bergeles, G. 2001. Numerical Evaluation of Alternate Tube Confirugations for Particle Deposition Rate Reduction in Heat Exchanger Tube Bundles. International Journal of Heat and Fluid Flow, 22, 525–536.
12. [12] Mavridou, S. G., Bouris, D. G. 2012. Numerical Evaluation of a Heat Exchanger with Inline Tubes of Different size for Reduced Fouling Rates. International Journal of Heat and Mass Transfer 55, 5185–5195.
13. [13] Han, H., He, Y. A., Tao, W. Q., Li, Y. S. 2014. A Parameter Study of Tube Bundle Heat Exchangers for Fouling Rate Reduction. International Journal of Heat and Mass Transfer 72, 210–221.
14. [14] Caputo, A. C., Pelagagge, P. M., Salini, P. 2011. Joint Economic Optimization of Heat Exchanger Design and Maintenance Policy. Applied Thermal Engineering, 31, 1381-1392.
15. [15] Bell, K. J. 1988. Delawere Method for Shell Side Design. Heat Transfer Equipment Design Hemisphere Publising, 41(10), 145-167.
16. [16] Taborek, J. 1983. Heat Echangers Design Handbook. Section 3.3. Shell and Tube Heat Exchangers: Single Phase Flow, Hemisphere Publishing, Washington, DC, 992 s.
17. [17] Karimi Donaa, M. H., Jalaliradb, M. R. 2014. Software Evaluation Via a Study of Deviations in Results of Manual and Computer-Based Step-Wise Method Calculations for Shell and Tube Heat Exchangers, International Journal of Applied Science and Engineering, 12, 2, 117-126.
18. [18] Kara, Y. A., Güraras, Ö. 2004. A Computer Program for designing of Shell-and-Tube Heat Exchangers. Applied Thermal Engineering, 24, 1797-1805.
19. [19] Kakaç, S., Liu H. 2002. Heat Exchangers: Selection Rating and Thermal Design Second Edition. CRC Press Taylor and Francis Group Publishing, Washington, DC, 520s.
20. [20] Genceli, O. F. 1999. Heat Exchangers, Birsen Publishing, İstanbul, 424 s.