2 Flow Measurement

1 Buidangthanh.3i@gmail.com Ha Noi, March 2012 1 MEASUREMENT TECHNOLOGY FLOW MEASUREMENT BUI Dang Thanh, NGUYEN Thi Lan Huong School of Electrical Engineering, Hanoi University of Science and Technology 1 Dai Co Viet road, Hà Nôi, Viêt Nam Buidangthanh.3i@gmail.com Ha Noi, March 2012 2 Presentation outline 1. Introduction 2. Flow measurement methods  Turbine  Diffiretial Pressure  Vortec  Magnetic  Temperature  Ultrasonic  Coriolit 3. Symbols in industry 4. Conclusion 5. References  What is the flow? Mass flow rate?  Why do we have to measure it? Buidangthanh.3i@gmail.com 3 Introducion Ha Noi, March 2012 Turbine method Buidangthanh.3i@gmail.com Ha Noi, March 2012 4 2  Turbine, or spin-type, flow sensors (also called flowmeters), employ a paddle wheel or propeller placed in the line of flow. The rotational velocity of the wheel is directly proportional to flow velocity.  A small magnet is attached to one of the blades, and a Hall-effect sensor is mounted in the housing * Buidangthanh.3i@gmail.com 5 Ha Noi, March 2012 Introduction to Turbine method Buidangthanh.3i@gmail.com 6 Turbine principle Ha Noi, March 2012  Axial turbines perform best when measuring clean, onditioned, steady flows of gases and liquids with low kinematic viscosities (below about 10–5 m2s–1, 10 cSt, although they are used up to 10–4 m2s–1, 100 cSt), and are linear for subsonic, turbulent flows. Under these conditions, the inherent mechanical stability of the meter design gives rise to excellent repeatability performance.  Not including the special case of water meters, which are described later, the main performance characteristics are: Buidangthanh.3i@gmail.com 7 Ha Noi, March 2012 Turbine method characteristics Buidangthanh.3i@gmail.com 8 Ha Noi, March 2012 Industrial Instruments 3 Differential pressure method Buidangthanh.3i@gmail.com Ha Noi, March 2012 9  This group of flow sensors is based on the fact that pressure in a moving fluid is proportional to the flow. The pressure is detected with a pressure sensor; based on the physical dimensions of the system, the flow can be calculated.  The simplest flow sensor is called the orifice plate (Figure ), and is simply a restriction in the pipe that causes a pressure drop in the flow, much like a resistor that causes a drop in voltage in a circuit. Buidangthanh.3i@gmail.com 10 Ha Noi, March 2012 Differential pressure principle Differential pressure principle (Conti.) Buidangthanh.3i@gmail.com 11 Ha Noi, March 2012  This sensor requires two pressure ports, one upstream and one downstream of the restriction. The flow is proportional to the pressure difference between these ports and is calculated as follows: Buidangthanh.3i@gmail.com 12 Differential pressure principle (Conti.) Ha Noi, March 2012 4  Low cost  Easy to install, to maintenance and replace  Impact to flow  Use for liquid Buidangthanh.3i@gmail.com 13 Ha Noi, March 2012 Characteristics of Differential pressure method Buidangthanh.3i@gmail.com 14 Ha Noi, March 2012 Industrial Instruments  Differentiall pressure measurement is a universal flow measurement for liquids, gases and vapors. Differential pressure flow meter always provide accurate results even with large bores, high temperature and extreme pressure.  Primary differential pressure devices, like SITRANS F O orifice, are standardized mechanical flow sensors according DIN EN ISO 5167 which are used for volume and mass flow measurement. The SITRANS F O orifice are suitable for non-corrosive and corrosive gases, vapors and liquids; permissible operating temperature - 60 to +570 °C. The created differential pressue will be converted with the help of a differential pressure transmitter SITRANS P delta P into a proportional flow signal. For calculation of the SITRANS F O orifice to DIN EN ISO 5167 is an completed filled out questionnaire necessary. Vortex method Buidangthanh.3i@gmail.com Ha Noi, March 2012 15 Introduction to Vortex method  The vortex shedding flowmeter first emerged 25 to 30 years ago and has steadily grown in acceptance since then to be a major flow measurement technique. Its appeal is due, in part, to the fact that it has no moving parts yet produces a frequency output that varies linearly with flow rate over a wide range of Reynolds numbers.  The vortex meter has a very simple construction, provides accuracy (1% or better) comparable to higher priced and/or more maintenance-intensive techniques, and works equally well on liquids and gases. Buidangthanh.3i@gmail.com 16 Ha Noi, March 2012 5 Vortex method principle  Probably the first time, ages ago, that anyone placed a blunt obstacle in a flowing fluid, he or she observed the whirlpools or vortices that naturally form and shed downstream. In everyday life, examples of vortex shedding are numerous.  The undulation of a flag is due to vortex shedding from the pole, and the singing of telephone wires in a strong wind is due to shedding from the wires.  Analysis by Theodore von Karman in 1911 described the stability criterion for the array of shed vortices. Consequently, when a stable array of vortices form downstream from an obstacle, it is often referred to as the von Karman vortex street. Buidangthanh.3i@gmail.com 17 Ha Noi, March 2012 Vortex method principle (Cont.)  Very early on, it was noted that, for a large class of obstacles, as the velocity increased, the number of vortices shed in a given time (or frequency of vortex shedding) increased in direct proportion to the velocity. * Buidangthanh.3i@gmail.com 18 Ha Noi, March 2012 Vortex method  Using for measuring the liquid, air and steam flow  Another method of flow measurement involves placing a bluff body (called a shedder bar) in the path of the fluid. As the fluid passes this bar, disturbances in the flow called vortices are created. The vortices trail behind the cylinder, alternatively from each side of the bluff body.  This vortex trail is called the Von Kármán vortex street after von Kármán's 1912 mathematical description of the phenomenon. The frequency at which these vortices alternate sides is essentially proportional to the flow rate of the fluid. Buidangthanh.3i@gmail.com 19 Ha Noi, March 2012 Vortex method  Inside, atop, or downstream of the shedder bar is a sensor for measuring the frequency of the vortex shedding.  This sensor is often a piezoelectric crystal, which produces a small, but measurable, voltage pulse every time a vortex is created.  Since the frequency of such a voltage pulse is also proportional to the fluid velocity, a volumetric flow rate is calculated using the cross sectional area of the flow meter. Buidangthanh.3i@gmail.com 20 Ha Noi, March 2012 6 Vortex method  The frequency is measured and the flow rate is calculated by the flowmeter electronics using the equation where is the frequency of the vortices, the characteristic length of the bluff body, is the velocity of the flow over the bluff body, and is the Strouhal number, which is essentially a constant for a given body shape within its operating limits.  Quite accuracy (error < 0,5%). Buidangthanh.3i@gmail.com 21 Ha Noi, March 2012 Buidangthanh.3i@gmail.com 22 Vortex principle Ha Noi, March 2012  This is the best instrument for measuring the air flow. Buidangthanh.3i@gmail.com 23 Ha Noi, March 2012 Vortex method Buidangthanh.3i@gmail.com 24 Ha Noi, March 2012 Industrial Instruments 7 Electro-magnetic method Buidangthanh.3i@gmail.com Ha Noi, March 2012 25  If a liquid is even slightly conductive (and many are), a magnetic flowmeter can be used. Shown in Figure , the magnetic flowmeter has no moving parts and presents no obstruction to the flow. A nonconducting section of pipe is placed in a magnetic field. * Buidangthanh.3i@gmail.com 26 Ha Noi, March 2012 Electro-magnetic method Electro-magnetic principle  Magnetic flowmeters have been widely used in industry for many years. Unlike many other types of flowmeters, they offer true noninvasive measurements.*  They can measure reverse flows and are insensitive to viscosity, density, and flow disturbances. Electromagnetic flowmeters can rapidly respond to flow changes and they are linear devices for a wide range of measurements. ** Buidangthanh.3i@gmail.com 27 Ha Noi, March 2012 Electro-magnetic principle (Cont.)  As in the case of many electric devices, the underlying principle of the electromagnetic flowmeter is Faraday’s law of electromagnetic induction.  The induced voltages in an electromagnetic flowmeter are linearly proportional to the mean velocity of liquids or to the volumetric flow rates.  As is the case in many applications, if the pipe walls are made from nonconducting elements, then the induced voltage is independent of the properties of the fluid. Buidangthanh.3i@gmail.com 28 Ha Noi, March 2012 8 Electro-magnetic principle (Cont.)  The accuracy of these meters can be as low as 0.25% and, in most applications, an accuracy of 1% is used.  At worst, 5% accuracy is obtained in some difficult applications where impurities of liquids and the contact resistances of the electrodes are inferior as in the case of low-purity sodium liquid solutions. Buidangthanh.3i@gmail.com 29 Ha Noi, March 2012 Electro-magnetic principle (Cont.)  Faraday’s Law of Induction • This law states that if a conductor of length l (m) is moving with a velocity v (m s–1), perpendicular to a magnetic field of flux density B (Tesla), then the induced voltage e across the ends of conductor can be expressed by: • The principle of application of Faraday’s law to an electromagnetic flowmeter is given in Figure The magnetic field, the direction of the movement of the conductor, and the induced emf are all perpendicular to each other. Buidangthanh.3i@gmail.com 30 Ha Noi, March 2012 Electro-magnetic principle (Cont.)  The induced voltage as a function of the flow:  Equation above indicates that in a carefully designed flowmeter, if all other parameters are kept constant, then the induced voltage is linearly proportional to the liquid flow only Buidangthanh.3i@gmail.com 31 Ha Noi, March 2012 Buidangthanh.3i@gmail.com 32 Ha Noi, March 2012 Electro-magnetic principle 9  Although the induced voltage is directly proportional to the mean value of the liquid flow, the main difficulty in the use of electromagnetic flowmeters is that the amplitude of the induced voltage is small relative to extraneous voltages and noise. Noise sources include: – Stray voltage in the process liquid – Capacitive coupling between signal and power circuits – Capacitive coupling in connection leads – Electromechanical emf induced in the electrodes and the process fluid – Inductive coupling of the magnets within the flowmeter Buidangthanh.3i@gmail.com 33 Ha Noi, March 2012 Electro-magnetic principle Buidangthanh.3i@gmail.com 34 Ha Noi, March 2012 Industrial Instruments SITRAN F M MAG 1100 - SIEMENS Description SITRANS F M MAG 1100 is a wafer design sensor in stainless steel with highly resistant liners and electrodes and is designed for the general industry environment. The flangeless wafer design meets all flange standards. The SITRANS F M MAG 1100 is used in all industries where the corrosion-resistant stainless steel housing and the highly resistant liner and electrodes fit even the most extreme process media. In order to have a complete flowmeter please combine it with one of the following MAG transmitters: SITRANS F M MAG 5000: Cost efficient transmitter, accuracy of + 0.4 % of flow rate SITRANS F M MAG 6000: Bus communication, batch function and accuracy of + 0.2 % of flow rate SITRANS F M MAG 6000 I: Alu enclosure, Ex approvals, bus communication, batch function and accuracy of + 0.2 % of flow rate Application examples: Process industry, Chemical industry, Water treatment Buidangthanh.3i@gmail.com 35 Ha Noi, March 2012 Industrial Instruments Meassuring range 0 to 10 m/s Nominal Sizes From DN 2 to DN 100 (1/12" to 4") Accuracy 0.2 % ±1 mm/s 0.4 % ±1 mm/s (PFA) Operating Pressure Max. 40 bar (Max. 580 psi) Ambient temperature From -40 to 100 °C (-40 to 212 °F) Medium temperature From -30 to 200 °C (-22 to 390 °F) Liners Ceramics PFA Electrodes Platinum Hastelloy Material Stainless steel AISI 316L (1.4404) Approvals ATEX - 2 GD Zone 1, FM Class 1 div 2 Buidangthanh.3i@gmail.com 36 Ha Noi, March 2012 Industrial Instruments Benefits - SITRAN F M MAG 1100 - SIEMENS  Compact wafer design meets EN 1092, DIN and ANSI flange standards  Easy Plug & Play field changeability of transmitter  Compact or remote mounting possible  Highly resistant liner and electrodes that are suitable for most extreme process media  Designed to allow patented MAG in-situ verification using the SENSORPROM fingerprint 10 Thermal method Buidangthanh.3i@gmail.com Ha Noi, March 2012 37 Thermal method Buidangthanh.3i@gmail.com 38 Ha Noi, March 2012  With two heater control modes and two evaluation modes, there are six operational modes shown in Table and three types of thermal mass flowmeters:  Thermal mass flowmeters that measure the effect of the flowing fluid on a hot body (increase of heating power with constant heater temperature, decrease of heater temperature with constant heating power). *  Thermal mass flowmeters that measure the displacement of temperature profile around the heater, which is modulated by the fluid flow. **  Thermal mass flowmeters that measure the passage time of a heat pulse over a known distance.*** Thermal flow sensors (Cont.) Buidangthanh.3i@gmail.com 39 Ha Noi, March 2012 Thermal flow sensors (Cont.) Buidangthanh.3i@gmail.com 40 Ha Noi, March 2012  The sensor element, whether it is a wire or a film, should be a resistor that has a resistance with a high temperature coefficient a. For most sensor materials, the temperature dependence can simply be expressed by a first-order function: [...]... Buidangthanh.3i@gmail.com Ha Noi, March 20 12 50 Buidangthanh.3i@gmail.com Ha Noi, March 20 12 52 13 Ultrasonic Flowmeters - Install Coriolis method Buidangthanh.3i@gmail.com Ha Noi, March 20 12 53 Buidangthanh.3i@gmail.com Industrial Instruments Ha Noi, March 20 12 55 Introduction to Coriolis method  Coriolis flowmeters were developed in the 1980s to fill the need for a flowmeter that measures mass directly,... linearization Ha Noi, March 20 12 43 Thermal method characreristics Thermal flow sensors (Cont.) Buidangthanh.3i@gmail.com Ha Noi, March 20 12 42 Buidangthanh.3i@gmail.com Ha Noi, March 20 12 44 11 Industrial Instruments Ultrasonic Flowmeters  Flow is one of the most important physical parameters measured in industry and water management *  For many years, differential pressure types of flowmeters have been... method Buidangthanh.3i@gmail.com Ha Noi, March 20 12 46 Buidangthanh.3i@gmail.com Ha Noi, March 20 12 48 12 Ultrasonic Flowmeters (Cont.) Ultrasonic Flowmeters (Cont.)  The acoustic method of discharge measurement is based on the fact that the propagation velocity of an acoustic wave and the flow velocity are summed vectorially *  If there are no transverse flow components in the conduit, these two transmit... temperature measurement ensures optimum accuracy on mass flow, density and % fraction Buidangthanh.3i@gmail.com Ha Noi, March 20 12 74 Buidangthanh.3i@gmail.com Ha Noi, March 20 12 76 19 References 1 http://www.yokogawa.com 2 http://www.abb.com 3 http://www.wikipedia.org 4 http://www.automation.siemens.com 5 Video from: http://www.products.endress.com /flow Buidangthanh.3i@gmail.com Ha Noi, March 20 12 77 Thank... flowmeters is nearly independent of pipe diameter, whereas the price of electromagnetic flowmeters increases drastically with pipe diameter Buidangthanh.3i@gmail.com Ha Noi, March 20 12 45 Buidangthanh.3i@gmail.com Ha Noi, March 20 12 47 Ultrasonic Flowmeters  There are various types of ultrasonic flowmeters in use for discharge measurement: (1) Transit time: This is today’s state-of-the-art technology and most... in some cases Ha Noi, March 20 12 Ha Noi, March 20 12 Industrial Instruments The SITRANS F C MASS 6000 Ex - Transmitter Coriolis method characteristics -Disadvantages Buidangthanh.3i@gmail.com Buidangthanh.3i@gmail.com 66 Buidangthanh.3i@gmail.com Ha Noi, March 20 12 68 17 Industrial Instruments –Sensors The SITRANS F C MASS 21 00 DI 1.5 Industrial Instruments Accuracy, mass flow Outputs 1 current 1 pulse... transmitter interface  Accurate measurement and fast batching due to flow step response with an 30 Hz update rate  Superior noise immunity due to a patented DFT (Discrete Fourier Transformation) algorithm  Built-in batch controller with compensation and monitoring comprising 2 stage batching Ha Noi, March 20 12 Ha Noi, March 20 12 71 Industrial Instruments –Sensors The SITRANS F C MASS 21 00 DI 1.5 (Conti.) Industrial... widely applied flow measuring device for fluid flows in pipes and open channels that require accurate measurement at reasonable cost **  Electromagnetic and ultrasonic flowmeters Whereas ultrasonic flowmeters can be applied in nearly any kind of flowing liquid, Electromagnetic flowmeters require a minimum electric conductivity of the liquid for operation  In addition, the cost of ultrasonic flowmeters... conduit, these two transmit times of acoustic pulses are given by: Buidangthanh.3i@gmail.com Ha Noi, March 20 12  Block diagram of a transit time ultrasonic flowmeter using oversampling for higher resolution 49 Buidangthanh.3i@gmail.com Ultrasonic Flowmeters (Cont.) Ha Noi, March 20 12 51 Ultrasonic Flowmeters  Since the transducers are generally used both as transmitters and receivers, the difference... Foundation Fieldbus Display 3 x 20 characters Enclosure Ratings IP67 Ambient temperature From -20 °C to 50 °C (-4 °F to 122 °F) Approvals  The SITRANS F C MASS 21 00 DI 1.5 has demonstrated superior performance in numerous applications and field trails relating to mass flowand density accuracy and turn down ratio  The single continuous tube design without internal welds, reductions or flow splitters, offers . 0,5%). Buidangthanh.3i@gmail.com 21 Ha Noi, March 20 12 Buidangthanh.3i@gmail.com 22 Vortex principle Ha Noi, March 20 12  This is the best instrument for measuring the air flow. Buidangthanh.3i@gmail.com 23 Ha Noi, March 20 12 Vortex. 20 12 Buidangthanh.3i@gmail.com 52 Ha Noi, March 20 12 Ultrasonic Flowmeters 14 Buidangthanh.3i@gmail.com 53 Ha Noi, March 20 12 Ultrasonic Flowmeters - Install Buidangthanh.3i@gmail.com 54 Ha Noi, March 20 12 Industrial. flow. Buidangthanh.3i@gmail.com 23 Ha Noi, March 20 12 Vortex method Buidangthanh.3i@gmail.com 24 Ha Noi, March 20 12 Industrial Instruments 7 Electro-magnetic method Buidangthanh.3i@gmail.com Ha Noi, March 20 12 25  If a liquid