Measuring Local Crystallization Fouling in a Double-Pipe Heat Exchanger

Abstract

Although fouling is a problem varying in space and time, sizing and assessment of a process apparatus is almost always based on one single integral fouling resistance value. Furthermore, the integral fluid dynamic behavior, e.g. the development of time-dependent pressure drop in a heat exchanger, can be influenced by local constrictions. While it is generally possible to determine the time dependency of the integral fouling behavior, local differences are not taken into consideration at present. Therefore, this paper introduces a metrological, an incremental and a segmental approach to study the local development of crystallization fouling by calcium sulfate in a countercurrent double-pipe heat exchanger. The consecutive approaches allow for thermal, volumetric, gravimetric, and optical fouling investigations, aiming to examine the axial distribution of deposit as well as local differences in the deposit morphology. All methods provided congruent results and local fouling could be described properly. An almost clean surface at the colder end of the heat exchanger and an exponential increase of deposit thickness were observed towards the hot end. Hence, the section near to the hot water inlet turned out to be a key area with regards to increasing fouling mass and structural changes of the layer.

Additional information

Notes on contributors

Florian Schlüter

Florian Schlüter is a PhD student/research assistant at the Institute for Chemical and Thermal Process Engineering, Technische Universität Braunschweig, Germany (ICTV Research Group Fouling & Cleaning). In 2014, he received a Dipl.-Ing. degree in bioengineering from the Technische Universität Braunschweig, Germany. Currently he continues working on local crystallization fouling in double-pipe heat exchangers.

Lukas Schnöing

Lukas Schnöing is a PhD student/research assistant at the Institute for Chemical and Thermal Process Engineering, Technische Universität Braunschweig, Germany (ICTV Research Group Fouling & Cleaning). In 2016, he received a MSc degree in bio- and chemical engineering from the Technische Universität Braunschweig. Currently he is working on the deposition behavior of food ingredients on modified surfaces.

Hans Zettler

Hans Zettler, Vice President, Global Sales & Marketing, joined HTRI (Heat Transfer Research, Inc.) while completing his PhD in Chemical Engineering at the University of Surrey, Guildford, UK. He also possesses a mechanical engineering degree (Dipl.-Ing.) from the Technical University Karlsruhe, Germany. He oversees HTRI’s sales & marketing efforts around the globe. He is a member of the German Engineering Society (VDI), a member of the VDI-GVC Working Party on Heat and Mass Transfer, an associate member of the Institution of Chemical Engineers (IChemE), and a committee member of the Heat Transfer Society, United Kingdom.

Wolfgang Augustin

Wolfgang Augustin is a senior researcher at the Institute for Chemical and Thermal Process Engineering, Technische Universität Braunschweig, Germany. He received his Dr. -Ing. in 1992 in Chemical Engineering from Technische Universität Braunschweig. His main research interests are heat and mass transfer, fouling and cleaning and surface interactions on the micro scale level.

Stephan Scholl

Stephan Scholl is a professor of chemical and thermal process engineering at the Technische Universität Braunschweig, Germany. He received his doctorate degree in 1991 from the Technical University of Munich. After 11 years with BASF AG, Ludwigshafen, Germany, he joined Technische Universität Braunschweig in 2002. His main research areas are heat and mass transfer with an emphasis on fouling and viscous systems, separation processes in biotechnological applications, as well as process intensification.