Experimental study for flow characteristics and performance evaluation of butterfly valves

Transcription

1 IOP Conference Series: Earth and Environmental Science Experimental study for flow characteristics and performance evaluation of butterfly valves To cite this article: C K Kim et al 2010 IOP Conf. Ser.: Earth Environ. Sci View the article online for updates and enhancements. Related content - Flow characteristics and performance evaluation of butterfly valves using numerical analysis S Y Jeon, J Y Yoon and M S Shin - Controlling the cavitation phenomenon of evolution on a butterfly valve G Baran, I Catana, I Magheti et al. - Parametric performance evaluation of a hydraulic centrifugal pump M W Heo, K Y Kim, S B Ma et al. This content was downloaded from IP address on 05/02/2018 at 13:44

2 Experimental study for flow characteristics and performance evaluation of butterfly valves 1. Introduction C K Kim 1, J Y Yoon 2 and M S Shin 1 1 Department of Mechanical Engineering, Hanyang University 17 Haengdang-dong Seongdong-gu, Seoul, , Republic of Korea 2 Division of Mechanical and Management Engineering, Hanyang University 1271 Sa-3-dong Sangnok-gu, Ansan, , Republic of Korea kck0513@hanyang.ac.kr Abstract. The industrial butterfly valves have been applied to transport a large of fluid with various fields of industry. Also, these are mainly used a control of fluid flux to the water and waste-water pipeline. Present, butterfly valves are manufacturing for multiplicity shape of bodies and discs with many producers. However, appropriate performance evaluation was not yet accomplished to compare about these valves through experiments. This study is performed the experiment of flow characteristics and performance of manufactured 400A butterfly valves for the water and waste pipeline, and compared experimental results. We performed experiments that were controlled fixed a differential pressure condition (1 psi) and the range of the flow rate conditions (500 m 3 /hr ~ 2500 m 3 /hr), and also opened the disc of valves to a range of angle from 9 degree to 90 degree. We investigated and compared the valve flow coefficient and the valve loss coefficient of results through experiments with each butterfly valve. Recent, the industry fields have been used variety the control valves for effectively control of a flow rate. The valve is the fluid device for the control of the fluid characteristics such as flow rate, direction, pressure and temperature, which it was basically performed four functions such that on-off, throttling, non-return and overpressure. In generally, a variety of control valves such as the butterfly valve, the ball valve, the globe valve, and the gate valve. A butterfly valve is used to open and close the pipeline, and to control the flow rate by rotating a disc with relatively low pressure. According to the location of the rotating axis of the valve disc, butterfly valves are classified into the concentric butterfly valve and the eccentric butterfly valve [1]. Especially, the butterfly valve was mainly used in large diameter pipeline system for the transportation of petroleum, gas, water and waste-water. Hence, it has relatively low pressure as compare with another control valve [2]. Thus, for this reason, many researchers have been carried out the experimental and the numerical study for the performance and characteristics of butterfly valve. Eom (1988) [3] treated with the butterfly valve as a controlling device for flows. However, none of them investigated three-dimensional throttled flow patterns with different valve openings. Kimura et al. (1995) [4, 5] presented two papers about the study of butterfly valve. The first paper researches the torque characteristics, and the second focuses on the pressure drop induced by the valve disc. Haung and Kim(1996) [6] investigated threedimensional analysis of partially open butterfly valve flows by using commercial code FLUENT, the characteristics of the butterfly valves flows at different valve disc angles with a uniform incoming velocity were investigated. Solliec and Danbon (1999) [7] analyzed the fluctuations of the instantaneous torque according to the valve/elbow spacing, and made recommendations for the installation of that kind of flow control valve. Kang et al. (2006) [8] investigated the effect of the attached fitting on the valve flow coefficient about four type of fitting such as L, T, Y, and the cross types using the experiments and the numerical analysis. Yi et al. (2008) [9] performed to design the optimization of eccentric butterfly valve using the characteristics function for the valve geometry, and showed results that performed the characteristics of flow and the structure analysis of the eccentric valve. In commonly, the main components of butterfly valve are consists of a body, a shaft, and a disc. Among the components, an important component to affect of flow is the disc of butterfly valve. Mainly, the valve flow c 2010 Ltd 1

3 coefficient and the valve loss coefficient were essential variables for the flow characteristics and the performance of the valve. These coefficients used to evaluate and to predict the performance of butterfly valve. Therefore, to evaluation for the flow characteristics and performance of butterfly valve through the experiments is important. However, previous experimental research was performed on the valve diameter 100mm and less by the limitation of experimental environments. And numerical researcher was also performed the investigation of numerical analysis that refer to experimental data. Accordingly, for a large diameter valve, evaluating of the flow characteristics and performance has the limitation for a reference of the previous research data. Furthermore, recent, for the case of the water supply pipe system, installed butterfly valve is need to validate the effective performance of the valve. For the case of the butterfly valve of a prototype or a trial product used at the industry field is also need to compare appropriate the experimental data for the validation of flow characteristics and performance. This study performed the 400mm diameter of butterfly valve on the water supply pipe system using the calibration system of large flow-meter that built in Korea Institute of Water and Environmental. However, it also evaluated the flow characteristics and the performance to compare with the fixed differential pressure of 1 psi and the differential pressure for the change of maximum flow rates of 5 cases. 2. Experiments 2.1 Experimental Equipment System Fig. 1 shows a scheme of an experimental equipment system. This experimental equipment system was used the calibration system of large flow-meter that was built in Korea Institute of Water and Environmental, Korea Water Resource Corporation. It has the greatest diameter of 800mm and Sump tank of 50 tons. Uncertainty at the flow rate of 2700 m 3 /h has the flow rate of 3.95 m 3 /h, this value could express that an expansion uncertainty in the confidence interval of 95% has 0.3% [10]. The experimental equipment system was constituted by IEC (1997) [13], which consists of a reservoir for preservation of returning water, a pump for lift up to a constant level head tank, the constant level head tank for supplying of constant flow rate of water, the upstream and the downstream throttling valves, thermometer, Electromagnetic flow meter, upstream/downstream pressure tap for measurement pressure drop and the test valve. The pipe for test section was installed a diameter of 400mm for the test valve, and the points of the pressure taps was located on 2D and 6D from a test valve, respectively. Fig. 1 Experimental system scheme 2

4 2.2 Experimental Method For this experiments, in order to compare the valve flow coefficient and the loss coefficient of test valves from the measured value of an independent variables e.g. pressure drop, flow rate. However, it was also performed to synthesize and to consider on the probability distribution that standardized a measurement error and an error range from the measurement uncertainty of related measure equipments and measured variables. The measurement uncertainty that expressed the best measurement capabilities (BMC) was ensured the limit of ± 1% (95% confidence level), was calculated a valve flow coefficient and a loss coefficient to represent a flow characteristics of the valve on the assured reliability in this experiments through the measured value. The valve experimental method was used the method of measurement that proposed by ANSI/ISA [12] or IEC [13]. Fig. 2 Valve test section scheme [13] For the estimation of a valve flow coefficient, experimental procedure described as follows. Fig. 2 showed test section scheme that was installed the test valve without attached fittings by requirement of piping. Differential pressure was then measured to a selected disc angle both the pressure taps and valve disc lift were used the formal valve disc lift rates: 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%. However, it performed to calculate the characteristics of a proper flow using the measured pressures at the formal the valve disc lift rates. The experiments performed to measure with the flow rate(q) and the differential pressure( Δ P ) between the upstream and the downstream pressure taps, and acquired the data of the case of the fixed differential pressure( Δ P = 1 psi) and the 5 cases of the differential pressure at the maximum flow rates(q max = 500, 1000, 1500, 2000, 2500 m 3 /hr), respectively. 2.2 Valve Flow Coefficient The valve flow coefficient importantly presented hydrodynamic characteristics of a control valve. It also has respect to valve type, diameter of valve, opening rate of valve and operating fluids. This valve flow coefficient is an important characteristic to investigate a valve performance and determined by differential pressure between upstream and downstream. When the differential pressure arises 1 psi at the specified valve disc lift rates with temperature 5 ~ 40 of water, Equation (1)[11, 12] was shown the flow rate of fluid through the valve as follows. (1) G C v = Q ΔP 2.3 Valve Loss Coefficient The fluid in a piping system passes through various valves, bends, elbows, inlets, exits, enlargements, and contractions in addition to the pipes. These components interrupt the flow of the fluid and cause additional losses because of the flow separation and mixing. A partially closed valve may cause the largest head loss in the system by the drop in the flow rate. Flow through valves is very complex, and a theoretical analysis is generally not plausible. However, this loss called the valve loss coefficient is determined experimentally and expressed as another representation of relation between pressure difference, fluid density and fluid average velocity following 3

5 Equations (2)[11, 12]. h K = u 2 /2 g ΔP h = ρg (2) 2.3 Valve Experimental Cases The valve experiments cases shown in Table 1. The valve experiments data was acquired the flow rate in the pipe and the differential pressure between the upstream and the downstream. The experiments condition cases also was controlled with the conditions that have the differential pressure ( Δ P = 1 psi) and the maximum flow rates (Q max =500, 1000, 1500, 2000, 2500 m 3 /hr) with each experiments of test valves, respectively. Horizontal axis of the figure was represents the valve disc lift rates, and vertical axis of the figure was represents each the valve flow coefficient and the valve loss coefficient values. Fig. 3 then shown that butterfly valves for this experiments. Table 1 Valve Experimental Cases Test Valve A Test Valve B Test Valve C Test Valve D Test Valve E Valve Type Single eccentric axis Double eccentric axis Double eccentric axis Triple eccentric axis Concentric axis (Slanted Disc) Valve Sheet Material Rubber Rubber Metal Metal Rubber Valve Experimental Conditions Differential Pressure (ΔP) Valve Disc Lift ( ) ΔP = 1 psi Q max = 500 m 3 /hr (Re = ) 1000 m 3 /hr (Re = ) 1500 m 3 /hr (Re = ) 2000 m 3 /hr (Re = ) 2500 m 3 /hr (Re = ) 9 ~ 90 (9 interval) 10 points (a) Test valve A (b) Test valve B 4

6 (c) Test valve C (d) Test valve D 3. Results and Discussion (e) Test valve E Fig. 3 Experimental Butterfly valves We performed the experiments of butterfly valves of diameter 400mm with a differential pressure condition case and 5 flow rate condition cases. We also compared to use the valve flow coefficient and the valve loss coefficient. These coefficients are importance parameters for valve characteristics and performance. However, the valve flow coefficient shows the flow capacity of a valve by disc opening lift and the valve loss coefficient shows a pressure loss for the flow rate by disc opening lift. Fig. 4 shows the valve flow coefficient of 5 test valves. Fig. 4 (a) shows the valve flow coefficient for fixed pressure condition with each valve and Fig. 4 (b) ~ (f) also shows to compare the valve flow coefficient for 5 cases of the flow rates. The valve flow coefficient curves of test valves generally showed tendency of the equality curves that change to proportional a flow rate by the disc opening lifts. In the case of high flow rate condition (2000 m 3 /h ~), the valve flow coefficient curves clearly display different performance and show analogous with 1 psi pressure condition results. However, test valves A, B, and C have more high the valve flow coefficient values than triple eccentric axis and inclined disc concentric axis for test valve D, E. Performance of test valves A, B and C that have single, double eccentric axis, have meanings more the high capability performance at the same flow rate or Reynolds number. It therefore needs to consider a valve axis type for the butterfly valve design and selection, because of eccentric axis affects to a valve performance. We also obtained that valve sheet materials no make different to the valve flow coefficient values in these results. Fig. 5 shows to compare the valve loss coefficient on the log-scale with test valves. The valve loss coefficient have considered to design the pipe system with alike other hydrodynamic loss coefficients such as a pipe friction loss, a contraction loss, and expansion loss i.e. In generally, a valve loss coefficient of common butterfly valve showed a high value at the low valve disc lift less than 15%. These results also show the high valve loss coefficient value at the low disc opening lift. Test valves A, B, C, and D have a little different the valve loss coefficient values, however, they proper to use for flow control in the water and waste-water supply pipeline system. In the case of test valve E that has concentric axis slanted disc, it significantly has greater the valve loss coefficient values at the valve disc lift of range 10% ~ 20% than other test valves. It is to appropriate to use a 5

7 limited range of the valve disc lift between 20% and 100%. However, test valve E showed smaller the valve flow coefficient value and larger the valve loss coefficient valve than test valve A, B, C, and D. (a) ΔP = 1 psi (b) Q max = 500 m 3 /hr (c) Q max = 1000 m 3 /hr (d) Q max = 1500 m 3 /hr (e) Q max = 2000 m 3 /hr (f) Q max = 2500 m 3 /hr Fig. 4 Comparison of the valve flow coefficient with test valves 4. Conclusion This study has performed experiments with the butterfly valve of 5 cases for water supply system using the calibration system of large flow-meter that built in Korea Institute of Water and Environmental. The results obtained the valve flow coefficients and the loss coefficients that calculating velocities and differential pressure under 1 psi differential pressure condition and 5 cases flow rates conditions. It also compared and evaluated the flow characteristics and performance for test valves through those results. It obtained conclusion as follows: (1) The valve flow coefficient under the high flow rate nearly shows to similar curves of the 1 psi differential pressure condition. It also shows to appropriate in the high flow rate condition to obtain more accurate performance evaluation. Flow characteristics of the test valves have aspect of equality curve and relatively show to separate the high performance valve group and the low performance valve group. (2) The valve flow coefficient shows clearly different performance with test valves of 5 cases. In the results, test valves A, B, and C shows greater the valve coefficient value than test valves D, E. However, single/double eccentric valves have large the coefficient value than triple eccentric and concentric slanted disc. It is the valve axis type that significantly means to affect the flow characteristics and the valve performance. (3) The valve loss coefficient shows to compare with 5 test valves. Test valve E that has concentric axis inclined disc shows larger loss coefficient value between valve disc lift of 10% ~ 20% than other test valves. It also has relatively low valve performance. Results of the test valves need to consider for applying the water supply pipeline system. 6

8 (a) ΔP = 1 psi (b) Q max = 500 m 3 /hr (c) Q max = 1000 m 3 /hr (d) Q max = 1500 m 3 /hr (e) Q max = 2000 m 3 /hr (f) Q max = 2500 m 3 /hr Fig. 5 Comparison of the valve loss coefficient with test valves Acknowledgments This work was supported by Korean Water Resource Corporation, and 2 nd stage BK21 Foundation grant funded by the Korea government. Nomenclature C v G h K Δ P The valve flow coefficient Specific Gravity of Water Valve head loss[m] The valve loss coefficient Differential pressure[n/m 2 ] Q Q max u g ρ Volumetric flow rate[m 3 /hr] Maximum of volumetric flow rate[m 3 /hr] Mean velocity in pipe[m/s] Gravity acceleration[m/s 2 ] Density of water[kg/m 3 ] References [1] Skousen P L 2004 Valve Handbook (New York: McGraw-Hill, Inc) [2] Hutchison J W 1967 ISA handbook of control valves, 2nd edition Instrument Society of America (Pittsburg, USA) [3] Eom K 1988 Performance of Butterfly Valves as Flow Controller ASME J. of Fluid Eng. Vol [4] Kimura T, Tanaka T, Fujimoto K and Ogawa K 1995 Hydrodynamic Characteristics of a Butterfly - Prediction of Pressure Loss Characteristics ISA Transactions [5] Kimura T, Tanaka T, Fujimoto K and Ogawa K 1995 Hydrodynamic Characteristics of a Butterfly - Prediction of Torque Characteristics ISA Transactions [6] Huang C and Kim R H 1996 Three Dimensional Analysis of Partially Open Butterfly Valve Flows Transactions of the (ASME) J. of Fluids Eng [7] Danbon F and Solliec C 2000 Aerodynamic Torque of a Butterfly Valve-Influence of an Elbow on the Time-mean and Instantaneous Aerodynamic Torque (ASME) J. of Fluids Eng [8] Kang S K, Yoon J Y and Lee B H 2006 Numerical and Experimental Investigation on Backward Fitting 7

9 Effect on Valve Flow Coefficient Proc. IMech Part E: J. of Process Mechanical Eng [9] Yi S I, Shin M K, Shin M S, Yoon J Y and Park G J 2008 "Optimizing of the eccentric check butterfly valve considering the flow characteristics and structural safety Proc. IMech, Part E: J. of Process Mechanical Eng [10] Lee D K and Park J H 2008 Uncertainly Characteristics of Diverter for Flow meter Calibration System J. of Fluid Machinery(in Korean) 11(3) [11] IEC Industrial-process control valves: flow capacity - sizing equations for fluid flow installed conditions, Int. Electrotechnical Commission (Geneva, Switzerland) [12] ANSI/ISA Flow Equations for Sizing Control Valves ISA - The Instrumentation, Systems and Automation Society (North Carolina, USA) [13] IEC Industrial-process control valves: flow capacity - testing procedures Int. Electrotechnical Commission (Geneva, Switzerland) 8