MODELLING AND SIMULATION OF CORIOLIS FLOW METER USED FOR BUNKER FUEL OIL FLOW by IVAN KURNIA 3269978 Submitted in accordance with the requirements for MECH4841 A – Mechanical Engineering Project The University of Newcastle Faculty of Engineering and Built Environment School of Engineering, Discipline of Mechanical Engineering Supervisor: Date of Submission: Dr. Luo Rongmo 10 December 2018 DECLARATION I declare that this thesis is my own work unless otherwise acknowledged and is in accordance with the University’s academic integrity policy available from the Policy Library on the web at http://www.newcastle.edu.au/policylibrary/000608.html I certify that this assessment item has not been submitted previously for academic credit in this or any other course. 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Student name: Date: Ivan Kurnia 13-10-2018 i ACKNOWLEDGEMENTS I would like to thank you Dr Luo for his guidance for this report throughout the semester. ii TABLE OF CONTENTS DECLARATION ........................................................................................................................ i ACKNOWLEDGEMENTS .......................................................................................................ii TABLE OF CONTENTS ......................................................................................................... iii NOMENCLATURE .................................................................................................................. v CHAPTER 1 INTRODUCTION .............................................................................................. 1 1.1 Background ................................................................................................................. 1 1.2 Project Aim and Scope ................................................................................................ 1 1.3 Coriolis Flow Meter .................................................................................................... 1 1.3.1 Working Principle ................................................................................................ 1 ............................................................................................................................................ 2 1.3.2 Design Breakdown ............................................................................................... 3 1.3.3 Dimensions .......................................................................................................... 3 Figure 4: Specification summary of commercially available CFM. ...................................... 3 1.4 Governing Equations ................................................................................................... 4 1.4.1 Reynolds Number ................................................................................................ 4 Figure 5: Formula for Reynolds Number........................................................................... 4 1.4.2 Beam Theory........................................................................................................ 4 1.4.3 Arbitrary Lagrangian-Eulerian (ALE) Formulation ............................................ 5 Figure 8: ALE formulation used to find low Reynolds number effect. ................................. 5 1.5 Methodology ............................................................................................................... 5 Figure 9: ANSYS modelling of single bent tube for the project’s future experiment. .......... 6 1.6 GANTT Chart ............................................................................................................. 6 CHAPTER 2 LITERATURE REVIEW ................................................................................... 1 2.1 CMF Performance on Bunker Fuel ............................................................................. 1 2.2 Cause of Measurement Error....................................................................................... 1 2.2.1 Low Reynolds Number ........................................................................................ 1 2.2.2 Pressure ................................................................................................................ 1 2.2.3 Vibration .............................................................................................................. 2 2.2.4 Bubble Theory ..................................................................................................... 2 2.3 Fluids Passing Through CFM ..................................................................................... 2 iii 2.3.1 Heavy Oil ............................................................................................................. 2 2.3.2 Water .................................................................................................................... 2 REFERENCES .......................................................................................................................... 3 APPENDIX A – GANTT CHART ............................................................................................ 5 iv NOMENCLATURE 𝑅𝑒 Reynolds number Greek Letters Angular velocity Abbreviations CFD Computational Fluid Dynamics CFM Coriolis Flow Meter MPA Maritime and Port Authority of Singapore GVF Gas Volume Fraction cSt centistokes, unit of kinematic fluid viscosity Pa s Pascal second, unit of kinematic viscosity, which translates to 1000 cSt cP centipoise, unit of dynamic viscosity, translates to 1 mPa s v CHAPTER 1 INTRODUCTION 1.1 Background In the past 20 years, Coriolis flow meter (CFM) has become one of the most researched type of flow meter and gained wide usage in many industries, in tandem with continuous improvement in areas of computational fluid dynamics (CFD). It was predicted to attain the largest demand of all flow meters, overtaking differential pressure flow meter (Wang & Baker, 2014). Singapore has the largest bunkering port in the world and is a global leader in bunker fuel sales. Its MPA has mandated all bunker companies to use CFM for high viscosity oil since January 2017, citing improvement in quantitative transparency and transportation and storage efficiency. MPA also predicted that the variance in fuel quantity can be lowered from 0.7% to 0.5% by using CFM (Liang, 2016). Moreover, due to sheer scale of Singapore’s bunker industry, even small error can lead to serious money loss. A mere 2.26 M ton of disputed quantity can translate to $ 690 million dollars in cost according to ExxonMobil Asia Pacific representative (Liang, 2016). 1.2 Project Aim and Scope The project aims to identify factors related to oil viscosity that lead to inaccuracy in CFM reading and mitigate them. Other factors will also be addressed for CFM applications beyond the bunkering industry. The project will mainly focus on CFM application on high density, high viscosity bunker fuel flow. By reducing uncertainties on the already highly accurate CFM, more time and money can be saved in bunkering industry, keeping Singapore ahead of the bunkering competition. 1.3 Coriolis Flow Meter 1.3.1 Working Principle Below is the diagram for a bent U-shaped flow meter. Although there are many different types of CFM including straight tube ones, the mechanism is generally the same for all CFM. 1 Figure 1: Diagram for simple bent, double tube Coriolis flow meter. : The flow tube is vibrated at resonant frequency by the driver and when there is no flow, the inlet and outlet part are in phase. However, when flow is present, the frequency interaction with the flow leads to Coriolis acceleration of fluid particles. Such acceleration creates a Coriolis force directly proportional to the flowing fluid’s density and velocity. This creates phase difference between inlet and outlet in terms of time delay, which is then read by the motion sensor to obtain mass flow (Sultan & Hemp, 1989). The graph below shows how the phase difference is observed. Figure 2: Phase shift measurement for bent, double tube CFM. 2 1.3.2 Design Breakdown CFM design can be differentiated by their shapes and configurations, and the two are not mutually exclusive. There are straight and bent pipe design, which can have either single pipe or double pipe configuration. Across all industries, including bunkering, bent pipe is much more commonly used although single tube finds its niche in food processing industry (Anklin, Drahm, & Rieder, 2006). Figure 3: Available CFM models in the market. 1.3.3 Dimensions Below is the summary of CFM available for sales as of 2014, as found by Wang and Baker. They noted that the majority of CFM for sale have bent tube shape or its variations e.g. Vshaped and Ohm-shaped. Figure 4: Specification summary of commercially available CFM. 3 1.4 Governing Equations 1.4.1 Reynolds Number Because the report mainly focuses on oil viscosity, Reynolds number becomes an important parameter to consider. It is inversely proportional to viscosity, hence in the report’s case low Reynolds number will be investigated, like research done by Anklin and Kumar. ρ stands for oil density and µ for kinematic viscosity. V is fluid velocity and D is tube diameter. Figure 5: Formula for Reynolds Number 1.4.2 Beam Theory For measurement of deflection, the tube can be assumed as a beam and thus subject to beam theorem. Research on CFM goes back to 1958 (Wang and Baker, 2014) and so researchers have had used different theorem over the years. Figure 6 shows Euler beam formulation for a bent tube from Sultan and Hemp in 1989, while Figure 7 shows Timoshenko beam theory used by Wang and Hussain to find pressure effects on CFM in 2010. Figure 6: Euler beam theory for bent tube. 4 Figure 7: Timoshenko beam theory for straight tube. 1.4.3 Arbitrary Lagrangian-Eulerian (ALE) Formulation Below is the ALE formulation used by Anklin and Kumar during their experiment with Reynolds number. It is lauded for its high meshing accuracy and ability to split the fluid mesh from the tube, making the simulation stable and accurate. Figure 8: ALE formulation used to model the fluid. 1.5 Methodology Simulation of bunker oil flow will be carried out using CFD and physical experiment. The CFD model will be created using ANSYS student version. If possible, CFD experiments carried out in the journals will be replicated to measure their relevance to the project’s model. Should the model fail to deliver, it will be redone be it in terms of geometry or initial condition until a data trend is observed. Real life experiment will be carried out using water as the passing fluid, given the unviability of actual bunker fuel. 5 Figure 9: ANSYS modelling of single bent tube for the project’s future experiment. 1.6 GANTT Chart The GANTT chart for MECH4841A for the entire semester can be found under Appendix A. 6 CHAPTER 2 LITERATURE REVIEW 2.1 CMF Performance on Bunker Fuel CFM is very viable for high viscosity oil/gas mixtures, with mass flow error of 5% and 2.5% for gas and liquid respectively. Their experiment utilized oil viscosities of 50 to 500 cSt and GVF of 0-90%, with high accuracy reading observed even at 90% GVF. Although the margin of error slightly increased at lower viscosities, the overall accuracy for the two-phase flow is still outstanding (Tombs et al., 2018). Similarly, Henry et al. (2006) suggested that as viscosity tends to infinity, the measurement error for mass flow and density tends to zero. 2.2 Cause of Measurement Error 2.2.1 Low Reynolds Number Kumar and Anklin (2011) discovered that at low Reynold number, CFM reading may fluctuate due to presence of fluid-dynamic forces. Such effect is caused by periodic shear mechanism, which on encounter with the oscillatory Coriolis force, decreases the tube deflection. Part of the Coriolis force was spread out thin in the secondary circulation and does not contribute to deflection. The authors suggested compensation method using a function of Reynolds number, reducing error to under 0.2%, down from 0.5 – 1%. 2.2.2 Pressure Pressure also affects the reading but to a negligible extent. Wang and Hussain (2010), using linear damping model to investigate the pressure effects on CFM, found that newer CFM has pressure sensitivity of less than 0.01% per bar in contrast to older models averaging at 0.13%. An interesting finding is that most bent tube flow meter has negative pressure sensitivity while straight tube ones have positive pressure sensitivity. The mechanism behind such behaviour and pressure effects in general is currently unknown. 1 2.2.3 Vibration Study made by Ridder et al. (2014) shows that external vibrations at the CFM’s drive frequency gives rise to measurement error, regardless of algorithm used by the CFM. They proposed to minimise such influence with strong balancing system such as twin-tube configuration. However, this model does not work with CFM designed for low mass flow. Moreover, the magnitude of error greatly varies by algorithm used and it is still unclear how vibration creates error, hence it is hard to measure the extent of vibration influence on the reading (Clark & Cheesewright, 2003). 2.2.4 Bubble Theory The measurement error due to particle entrainment can be described under bubble theory assumptions. When acceleration of the two phases are different, phase decoupling occurs which causes negative error i.e. the reading is always below the real value. Two-phase flow is especially prone to large decoupling phase error (Nils, 2014). 2.3 Fluids Passing Through CFM 2.3.1 Heavy Oil The oil used in this report is heavy crude oil used for bunker fuel. It has density of at least 920 kg/m3 and can go above 1000 kg/m3 for very heavy crude oil (Anton Paar Wiki). The dynamic viscosity is around 10 000 cP. (Alaska Gas and Oil Association). 2.3.2 Water Water has density of about 1000 kg/m3 with slight fluctuations depending on temperature. Researchers commonly use this fluid in experiments aiming to identify and compensate causes of measurement error that are not viscosity related. 2 REFERENCES Wang, T., & Baker, R. (2014). Coriolis flowmeters: A review of developments over the past 20 years, and an assessment of the state of the art and likely future directions. Flow Measurement and Instrumentation,40, 99-123. doi:10.1016/j.flowmeasinst.2014.08.015 Liang, L. H. (2016, March 31). Singapore moves closer to mass flow meter bunkering. Retrieved December 10, 2018, from http://www.seatrade-maritime.com/news/asia/singaporemoves-closer-to-mass-flow-meter-bunkering.html Liang, L. H. (2016, December 29). Singapore enters 2017 with mandatory use of mass flow meter bunkering. Retrieved October 8, 2018, from http://www.seatrademaritime.com/news/asia/singapore-enters-2017-with-mandatory-use-of-mass-flow-meterbunkering.html The Basics of Flow Measurement with Coriolis Meters: Part 2. (2017, April 18). Retrieved from https://www.flowsolutionsblog.com/blog/the-basics-of-flow-measurement-withcoriolis-meters-part-2/ Sultan, G., & Hemp, J. (1989). Modelling of the Coriolis mass flowmeter. Journal of Sound and Vibration,132(3), 473-489. Retrieved October 10, 2018, from https://www.sciencedirect.com/journal/journal-of-sound-and-vibration/vol/132/issue/3. Anklin, M., Drahm, W., & Rieder, A. (2006). Coriolis mass flowmeters: Overview of the current state of the art and latest research. Flow Measurement and Instrumentation,17(6), 317-323. doi:10.1016/j.flowmeasinst.2006.07.004 Viscosity of Crude Oil – viscosity table and viscosity chart :: Anton Paar Wiki. (n.d.). Retrieved from https://wiki.anton-paar.com/en/crude-oil/ Kumar, V., & Anklin, M. (2011). Numerical simulations of Coriolis flow meters for low Reynolds number flows. Mapan,26(3), 225-235. doi:10.1007/s12647-011-0021-6 3 Wang, T., & Hussain, Y. (2010). Pressure effects on Coriolis mass flowmeters. Flow Measurement and Instrumentation,21(4), 504-510. doi:10.1016/j.flowmeasinst.2010.08.001 Ridder, L. V., Hakvoort, W., Dijk, J. V., Lötters, J., & Boer, A. D. (2014). Quantification of the influence of external vibrations on the measurement error of a Coriolis mass-flow meter. Flow Measurement and Instrumentation,40, 39-49. doi:10.1016/j.flowmeasinst.2014.08.005 Clark, C., & Cheesewright, R. (2003). The influence upon Coriolis mass flow meters of external vibrations at selected frequencies. Flow Measurement and Instrumentation,14(1-2), 33-42. doi:10.1016/s0955-5986(02)00065-1 Henry, M., Tombs, M., Duta, M., Zhou, F., Mercado, R., Kenyery, F., . . . Langansan, R. (2006). Two-phase flow metering of heavy oil using a Coriolis mass flow meter: A case study. Flow Measurement and Instrumentation,17(6), 399-413. doi:10.1016/j.flowmeasinst.2006.07.008 Basse, N. T. (2014). A review of the theory of Coriolis flowmeter measurement errors due to entrained particles. Flow Measurement and Instrumentation,37, 107-118. doi:10.1016/j.flowmeasinst.2014.03.009 Heavy Oil Vs. Light Oil. (2011, March). Retrieved December 10, 2018, from http://www.aoga.org/wp-content/uploads/2011/03/HRES-3.10.11-Lunch-Learn-BP-HeavyOil1.pdf 4 APPENDIX A – GANTT CHART 5