ScienceDirect. Development of a pressure pulsation damper for gas pressure regulators with account of operation parameters

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1 Available online at ScienceDirect Procedia Engineering 106 (2015 ) Dynamics and Vibroacoustics of Machines (DVM2014) Development of a pressure pulsation damper for gas pressure regulators with account of operation parameters Mikhail A. Ermilov a, *, Alexander N. Kryuchkov b, Maxim V. Balyaba b, Konstantin U. Shabanov c a Samara State Aerospace University, Moskovskoe shosse, 34, Samara, , Russian Federation b The Institute of Acoustic of Machines SSAU, Moskovskoe shosse, 34 campus building 14, office 324, 320, Samara, , Russian Federation c Gazprom Transgas Samara LLC, 106A Novo-Sadovaya St., Samara, , Russian Federation Abstract A design concept of a gas flow pulsation damper at a pressure regulator outlet is offered. It is formulated the operational principle of this damper, which contains the orifice with high and low resistance and also the stabilizer (vortex damper) of an outflow. Future references for choosing the diameter and the amount of passages in the orifices are also done. It is proposed the sequence of choosing the damper parameters, which contains the stages of tentative gas-dynamic calculation of the plain washer parameters on basis of the Saint-Venant-Wenzel formula and the final modeling, produced on basis of the numerical simulation. It is presented the pulsation damper, which was developed by the offered method The The Authors. Published by Elsevier by Elsevier Ltd. This Ltd. is an open access article under the CC BY-NC-ND license ( Peer-review under responsibility of organizing committee of the Dynamics and Vibroacoustics of Machines (DVM2014). Peer-review under responsibility of organizing committee of the Dynamics and Vibroacoustics of Machines (DVM2014) Keywords: Pneumatic and gas systems, gas pressure regulator, gas-distribution station, aerodynamic noise, gas throttling, sound power. 1. Introduction An important problem connected with operation of gas-distributing stations and knots is increased noise levels and vibrations caused by a high-speed gas flow rate downstream of pressure regulators. Such intensive gas flow occurs due to a high pressure drop (3 4 MPa) over gas pressure regulators. Significant values of sound pressure * Corresponding author. Tel.: ; address:emasamara@gmail.com The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( Peer-review under responsibility of organizing committee of the Dynamics and Vibroacoustics of Machines (DVM2014) doi: /j.proeng

2 278 Mikhail A. Ermilov et al. / Procedia Engineering 106 ( 2015 ) inside the pipe generate the vibration of the pipe walls [1, 2 and 3]. Such high-frequency vibration can lead to gradual destruction and damage of the pipes. This is the result of acoustic fatigue which is highly dangerous in the presence of asymmetric forms of natural oscillations of the pipe and in the case of the pipe branches and junctions in the construction [4, 5 and 6]. The Gas Pressure Regulators (PR) are intended to reduce and keep constant pressure at the set level [7]. Flow restriction occurs in the narrowest section of the PR. In the majority of cases (at critical pressure drop) speed in this section is supersonic. The gas flow at the PR output is a main source of the pipeline system noise (see Fig. 1). Fig. 1. Noise emission in pipeline system with the gas pressure regulator: 1-regulator; 2-output pipeline. The most effective way of the noise reduction during PR operation is installation of pressure pulsations dampers at its output [8]. The pressure pulsations damper has to effectively reduce noise of the regulator so as its capacity shouldn't change. 2. Theoretical basics of PPD development Noise of gas dynamic origin has random character and is usually observed in a wide range of frequencies. Intensity of gas dynamic noise increases with a flow rate and reaches maximum value at sonic and supersonic flow velocity. The acoustic power of W aк radiated by a flow is proportional to a flow speed at 6-8 ratios (depending on Mach number), to a gas density square in a flow and to the square of flow diameter [9]: W ак cv D k0 (1) V 0 3 зв where: k 0 - proportionality coefficient; p c - flow density, kg/m3; V - flow velocity; D - flow diameter, m; V s - sound speed, m/s. Therefore, to achieve the noise reduction of high-speed turbulent flows is possible by means of: flows speed reduction; reduction of gas in flows density; reduction of its diameters; step pressure decline.

3 Mikhail A. Ermilov et al. / Procedia Engineering 106 ( 2015 ) Method of PPD development As mentioned above, the most effective solution of the problem of noise and vibration of pipeline fittings is installation of a pressure pulsations damper at the output of the regulator which has the following functions: reduction of the pressure difference on the regulator and, thereby, a decrement of the maximum flow speed in the regulator; stepped restriction of the general pressure difference in order to reduce a gas speed in the damper elements; fragmentation of the flow in order to move the frequency of maximum of acoustic radiation of flows to the high-frequency area. Fig. 2. A fragment of pipeline system with the regulator (1) and a pressure pulsations damper (2). Depending on the output pressure of PR we can calculate the level of sound pressure generated by the regulator at a certain distance from an output pipe (see Fig. 3) by the method stated in [9]. This method also considers various modes of noise initiation in the valve depending on a structure of a gas flow (the aerodynamic modes) which borders crit are also shown at the Fig. 3. It is shown at the graph that there is such an output pressure P ex (at constant P inp ) at which the maximum level of sound pressure is observed. Therefore, the drop on PPD has to satisfy some conditions: pressure difference has to be such value, that pressure at the exit from the regulator P reg crit outp>p ex (2) pressure difference on the damper should not limit the capacity of all system in common (PR+PPD).

4 280 Mikhail A. Ermilov et al. / Procedia Engineering 106 ( 2015 ) Fig. 3. The schedule of change of acoustic level pressure of PR (PR aero acoustic operating modes are specified in figures). After the choice of the pressure difference on the PPD it is necessary to choose the number of its restriction steps (throttle plates) taking into account that in order to do such functions the pressure pulsation damper has to consist of 3 parts such as: discharging (reducing pressure difference on PR) part (with a condition (2) demanded pressure difference), including package from 1-2 throttle plates; pressure difference on these plates should be 85 90% of the general pressure difference for the PPD; fragmentation of the flow and consisting a series of plates (a package of plates from 4 7 throttle plates depending on the demanded efficiency of PPD) with small pressure difference, pressure difference on these plates should not be more than 10 15% of the general pressure difference for PPD; reduction of the flow whirls, containing a whirl rectifier which should work at a minimum possible pressure difference After the distribution of pressure difference at the above mentioned parts it is necessary to determine the diameter and number of orifices on each throttle plate, using a formula of Saint-Venan-Ventsel [10], for definition of mass flow 2 k 1 2k k k G F P1 1 k 1 (3) where: F - the total area of orifices in plates; - expense coefficient; k - adiabatic curve indicator; P 1 - entrance pressure; 1 - gas density at input; - pressure after a plate to pressure after relation coefficient.

5 Mikhail A. Ermilov et al. / Procedia Engineering 106 ( 2015 ) The choice of diameter and the number of orifices in throttle plates is necessary to do in such a way that, on the one hand, the velocity of gas in orifices should be less than the sound speed (this regulation is actual for throttle plates) and, on the other hand, it should be decreased softly for all throttle plates till the minimum possible speed, determined by crossection of the output pipeline. Holes diameter should be the minimum possible for more effective flow fragmentation. However, there are technological and exploitational restrictions for this diameter. The first restrictions are related with the difficulty and much labour intensity of making holes less than 1 mm in diameters, the second with the possibility of its choking and obstruction by condensate. The quantity of holes is regarded approximately and is précised during the virtual modeling of each plate in particular in ANSYS Fluent program package. Afterwards, such calculations are made regarding the whole model (see Fig. 4). The boundary conditions are mass consumption and pressure at the output for each plate in particular. Fig. 4. Pressure difference across a damper at 2,5 kg/sec mass flow rate. Consequently, an algorithm of PPD development was offered and it is shown in Fig. 5.

6 282 Mikhail A. Ermilov et al. / Procedia Engineering 106 ( 2015 ) Fig. 5. PPD development algorithm. Taken references: P inp - pressure at input of the damper, Pa; P outp pressure at output of the damper, Pa; G max - maximum mass consumption, kg/sec; K v consumption ratio; K r repressuring ratio; A s - sound speed in environment, m/sec; p environment density, kg/m 3 ; K adiabatic ratio; i - flow velocity, m/sec; i - précised flow velocity, m/sec; - possible inaccuracy.

7 Mikhail A. Ermilov et al. / Procedia Engineering 106 ( 2015 ) Pulsation damper is shown in Fig. 6, which was designed according to this algorithm for P inp =4.7 MPa, P outp = 0.7 MPa, G=2.5 kg/sec, the working body is methane. According to the testing of the physical model of the device, the PPD effectiveness is 34 dba. Conclusion Fig. 6. PPD sectional view of medium efficiency (throttle plates and whirl rectifier) for GDS. The method of pulsation dampers development after pressure regulators was offered. The principle of stepped throttling with the reduction and flattening of the output flow is the basis of the method. This method was tested on the damper for pressure regulator of the gas distribution station with an average efficiency. Acknowledgements The work was supported by Russian Federation Ministry of Education and Science. References [1] Eisinger, F. L., and Sullivan, R., 2010, Acoustic Power and Acoustic Pressure in Piping Systems Handling High Velocity Steam and Gases Through a Pressure Reducing Device, Proceedings of the ASME 2010 Pressure Vessels and Piping Division, PVP , July 18 22, 2010, Bellevue, Washington, [2] Beranek, L.L. Noise and Vibration Control Engineering: Principles and Applications / L.L. Beranek// Second Edition, Istvan, 2006 [3] Jury F.D. Fundamentals of aerodynamic noise in control valves / F.D. Jury // Technical monograph P. 23 [4] Cowling, F., Design Strategies for Acoustically Induced Vibration in Process Piping, Proceedings of Internoise 2012, New York, August [5] Nishiguchi, M., Izuchi H., Hayashi, I., and Minorikawa, G., Flow Induced Vibration Downstream of Tee Connection, 10th Proceedings of the International Conference on Flow-Induced Vibration, Dublin, July [6] Evans, G., Baker, J., and Swindell, R., Operator experience with using the Energy Institute Piping Vibration Guidelines to prevent Acoustic Induced Vibration fatigue failures, Proceeding of Internoise 2012, New York, August [7] Arzumanov, E.S., (1985) Gidravlicheskie reguliruushie organy sistem avtomaticheskogo upravleniya [Hydraulic regulating elements of automatic control systems]. Mashinostroeniye- Mechanical industry. 256 pp. (in Russian) [8] Udin, E.Y., (1985) Borba s shumom na proizvodstve [Noise control at manufacture]. Mashinostroeniye- Mechanical industry. 400 pp. (in Russian) [9] ISA (IEC Mod) Flow Equations for Sizing Control Valves, 72 pp. [10] Deitch, M.E., (1961) Technicheskaya i gazovaya dinamika [Technical and gas dynamics]. Gosenergoizdat-State energy publisher. 671 pp. (in Russian)