Ngày đăng: 07/09/2016, 16:24

User Guide PipeFlow is a trading name of Daxesoft Ltd http://www.pipeflow.co.uk Pipe Flow Expert User Guide Copyright Notice © 2010 All Rights Reserved Daxesoft Ltd Distribution Limited to Authorized Persons Only Trade Secret Notice The PipeFlow.co.uk and Daxesoft Ltd name and logo and all related product and service names, design marks, logos, and slogans are either trademarks or registered trademarks of Daxesoft Ltd All other product names and trademarks contained herein are the trademarks of their respective owners Printed in the United Kingdom – March 2010 Information in this document is subject to change without notice The software described in this document is furnished under a license agreement The software may be used only in accordance with the terms of the license agreement It is against the law to copy the software on any medium except as specifically allowed in the license agreement No part of this document may be reproduced or transmitted in any form or by any means electronic or mechanical, including photocopying, recording, or information recording and retrieval systems, for any purpose without the express written permission of Daxesoft Ltd Version 5.12 Table of Contents Table of Contents Table of Figures Introduction 13 Welcome to Pipe Flow Expert 13 Pipe Flow Expert Overview 13 Minimum Operating System Requirements 14 Registration and Licensing Information 15 Contacting PipeFlow.co.uk 17 Additional PipeFlow.co.uk Products 17 Interface and Menus 18 Menu Bar 18 File Menu 19 Edit Menu 20 Units Menu 21 Fluid Menu 21 Drawing Menu 22 Tools Menu 23 License Menu 23 Documentation Menu 23 Help Menu 24 Tool Bar 25 Tool Bar Buttons 25 Keyboard Shortcuts 28 Node Pane 29 Node Types 29 Tank Node Data 30 End Pressure Data 31 Join Point Data 32 Set Flow Demands Dialog 33 Pipe Pane 33 Pipe Features 34 Pipe Material data Dialog 35 Pipe Diameter Size Data Dialog 37 Pipe fitting friction coefficients Dialog 38 Set Component Pressure Loss Dialog 39 Set Control Data Dialog 40 Pump Data Dialog 41 Pipe Flow Expert User Guide Drawing Pane 43 Configuration Options Screen 44 Labeling Tab 45 Units Tab 46 Pipe Settings Tab 47 Node Updates Tab 49 Results Colors Tab 50 Calculations Tab 51 Results Tables 53 Viewing Individual Results 54 File and Design Operations 56 Creating a New Pipe System 56 Isometric System Options 56 Designing a Pipe System 57 Saving a System 57 Change the System View – Isometric Mode Toggle 58 Sending a System via E-mail 59 Printing a System 59 Saving a Screen Image 60 Saving a Drawing to an EMF Image 60 Emailing a Screen Image 60 System Options 61 Choosing Units (imperial/metric) 61 Choosing Item Labeling 62 Choosing the System Units 63 Choosing Pipe Drawing Defaults 64 Change attributes of more than one pipe 68 Node Updates 69 Results Colors 70 Configuring the Calculation Parameters 71 Fluid Zones 73 Defining Fluid Zones 73 Properties of Mixed Fluids 74 Two Phase Flow – Additional Pressure Drop 74 Fluids Database 75 Adding Fluids to the Fluid Database 76 Adding Gas Data to the Fluid Database 77 Tanks 78 Add a Tank 78 Nodes (Join Points) 80 Adding a Node 80 Pipes 82 Adding a Pipe 82 Adding a Pipe Material to the Database 85 Adding Pipe Size Data to the Database 85 Reversing the Pipe Flow 86 Shutting Off a Pipe in the System 86 Using the Pipe Sub-menu while drawing 87 Preventing Backflow in a pipe 88 Using the Default Pipe feature while drawing 88 Fittings and Valves 89 Adding a Fitting to a pipe 89 Adding a Fitting to the Database 91 Components 94 Adding a Component with a pressure loss 95 Cv and Kv Flow Coefficients 97 Adding a component/valve with a Cv or Kv value 97 Control Valves (FCV, PRV, BPV) 99 Adding a Flow Control Valve 101 Adding a Pressure Reducing Valve 101 Adding a Back Pressure Valve 102 Pumps 103 Adding a Pump 104 Working with the Pump Curve Graph 106 Adding a Fixed Flow Rate Pump 106 Note about fixed flow rate pumps 107 Adding a Fixed Head / Pressure Rise Pump 107 Example Pumps (with Flow versus Head curve) 108 Demand Flows 109 Adding a Demand Flow at a join point 109 Demand Pressures 111 Adding a Demand Pressure at an end node 111 Text Items 113 Adding Text to the drawing 113 Viewing, Modifying, and Deleting Items 114 Zooming in or Out in the Drawing Pane 114 Zooming in to a selected area 114 Viewing the whole System in the Drawing Pane 115 Pipe Flow Expert User Guide Panning a System in the Drawing Pane 115 Finding a Pipe or a Node 115 Mirror View of the Pipe System 115 Inverted View of the Pipe System 116 Viewing and Modifying System Data 116 Individual Item Viewing and Modifying 117 Moving Components in a System 117 Cutting, Copying, and Pasting Nodes & Pipes 118 Rotating selected items 119 Copying between drawings 120 Moving a Pipe to link at a new position 120 Using the Undo and Redo Functions 120 Deleting Components in a System 120 Deleting a Node or Pipe 121 Deleting a Group of Components 121 Deleting a Demand Flow 122 Deleting Fittings 122 Deleting a Component Pressure Loss 122 Deleting a Control Valve 123 Deleting a Pump 123 Calculations and Results 124 Calculating and Solving a System 125 Configuring the System Results 128 Viewing the System Results 130 Saving the System Results 130 Exporting the System Results 131 Redesigning the System 132 Amending the System 132 Create a PDF Report of the System Results 134 Example Systems 136 Example 01: Three Reservoirs 137 Example 01: Three Reservoirs 137 Example 02: Tank to Joint Outflow 138 Example 03: Gravity Flow to Three Outlet Points 139 Example 04: Fixed Flow Pumping to Three Tanks 140 Example 05: Fixed Head Pumping to Three Tanks 141 Example 06: Fixed Speed Pumping -Chemical Transfer System 142 Example 07: Pressurized Pumping Stations 143 Example 08: Water Circulation System 144 Example 09: Cooling – 12 Air Handling Units 145 Example 10: Compressed Air Distribution 146 Example 11: HVAC System 147 Example 12: Reverse Pipe 148 Example 13: Energy Recovery with Turbine System 149 Example 14: Top-up Tanks – Pressurized Recirculation System 150 Example 15: Replacement Pipe Size 151 Example 16: Step-by-Step – Walkthrough Example 152 Example 17: Pressure Reducing Valves 157 Example 18: Back Pressure Valves 158 Example 19: Multiple Fluid Zones 159 Example 20: Methane Pipeline Isothermal Flow 160 Example 21: Zoned Compressed Air Flow 161 Example Isometric 01: Chilled Water Piping System 162 Example Isometric 02: Three Floor HVAC System 163 Example Isometric 03: Water Circulation System 164 Example Isometric 04: Cooling with AHUs 165 Example Isometric 05: Production Area Cooling Alt Views 166 Example Isometric 06: Compressed Air Fluid Zones 167 Example Isometric 07: Fire Protection Sprinkler System 168 Example Isometric 08: Campus Chilled Water Cooling 169 Example Isometric 09: Water Mist Fire Protection 170 Calculation Theory and Method of Solution 171 Fluid flow states 171 Fluid viscosity 171 Reynolds numbers 172 Friction factors 172 Colebrook-White Formula 172 Friction Losses (resistance to flow) 172 Darcy-Weisbach Formula 173 Fitting head loss 173 ’K’ Factor fitting head loss calculation 173 Calculate total pressure loss 174 Energy and Hydraulic Grade Lines 174 Balanced flow state 175 Loops, Nodes and Pipes 175 Solving the unknown values 176 System Calculation Tolerances 177 System Components 177 Pipe Flow Expert User Guide Cv and Kv Flow Coefficients 177 Flow Control Valves 182 Pressure Reducing Valves 183 Back Pressure Valves 184 Pumps (with Flow versus Head Curve) 185 Fixed Flow Rate Pumps 185 Fixed Head / Pressure Rise Pumps 186 Net Positive Suction Head available 186 Two Phase Flow 186 Slurries 186 Working with compressible fluids 187 Considerations when using compressible fluids 187 Glossary 189 Index 190 Table of Figures Figure Pipe Flow Expert License Registration 15 Figure Pipe Flow Expert interface 18 Figure Menu bar 18 Figure File menu 19 Figure Edit menu 20 Figure Units menu 21 Figure Fluid menu 21 Figure Drawing menu 22 Figure Tools menu 23 Figure 10 Registration menu 23 Figure 11 Documentation menu 23 Figure 12 Help menu 24 Figure 13 Node pane for tanks 30 Figure 14 Node pane for demand pressures (End Pressure) 31 Figure 15 Node pane for join points 32 Figure 16 Set Flow Demands dialog 33 Figure 17 Pipe pane and Pipe Sub-menu 34 Figure 18 Pipe Material data dialog 35 Figure 19 Pipe diameter data dialog for size 37 Figure 20 Pipe fitting friction coefficients 38 Figure 21 Set Component Pressure Loss dialog 39 Figure 22 Set Control Data dialog 40 Figure 23 Pump Data dialog 41 Figure 24 Drawing Panes Standard or Isometric 43 Figure 25 Configuration Options dialog – Labeling tab 45 Figure 26 Configuration Options dialog – Units tab 46 Figure 27 Configuration Options dialog – Pipe Settings tab 48 Figure 28 Configuration Options dialog – Node Updates tab 49 Figure 29 Configuration Options dialog – Results Colors tab 50 Figure 30 Configuration Options dialog – Calculations tab 51 Figure 31 Results tables 53 Figure 32 View Individual Results 55 Figure 33 Save As dialog 58 Figure 34 Printing Information dialog 59 Figure 35 Configuration Options dialog – Labeling tab 62 Figure 36 Configuration Options dialog – Units tab 63 Figure 37 Configuration Options dialog – Pipe Settings tab 64 10 Pipe Flow Expert User Guide Figure 38 Pipe diameter data dialog with materials list 65 Figure 39 Pipe diameter data dialog with materials size 66 Figure 40 Pipe fitting friction coefficients dialog 67 Figure 41 Configuration Options dialog – Pipe Settings tab 68 Figure 42 Configuration Options dialog – Node Updates tab 69 Figure 43 Configuration Options dialog – Results Colors tab 70 Figure 44 Calculation settings 71 Figure 45 Fluid Zone Menu 73 Figure 46 Fluid data dialog 75 Figure 47 Properties of Gases 77 Figure 48 Node pane for tanks 78 Figure 49 Node pane for join points 80 Figure 50 Set Flow Demands dialog 81 Figure 51 Pipe diameter data dialog with materials list 83 Figure 52 Pipe diameter data dialog with materials size 84 Figure 53 Pipe Sub-Menu 87 Figure 54 Pipe fitting friction coefficients dialog 90 Figure 55 Adding a fitting in the Pipe fitting friction coefficients dialog 92 Figure 56 Choose symbol dialog 92 Figure 57 Sudden Contraction K value 93 Figure 58 Set Component Pressure Loss dialog 96 Figure 59 Adding a Cv / Kv flow coefficient value 98 Figure 60 Set Control Valve Data dialog 100 Figure 61 Add Pump Confirm dialog 104 Figure 62 Pump Data dialog 105 Figure 63 Fixed Flow Rate Pump 107 Figure 64 Fixed Head / Pressure Pump 108 Figure 65 Set Flow Demands dialog 110 Figure 66 Node pane for end pressures 111 Figure 67 Add Free Text Label Dialog 113 Figure 68 Network Data – Grid view 116 Figure 69 Result Log dialog 125 Figure 70 Pipe Flow Expert interface in Results mode 126 Figure 71 Results Tables 126 Figure 72 PDF Report Options Dialog 127 Figure 73 PDF Report Pages 127 Figure 74 Configuration Options dialog – Labeling tab 128 Figure 75 Configuration Options dialog – Units tab 129 Figure 76 Results Tables – All Results tab 130 Calculation Theory and Method of Solution 179 Pipe Flow Expert uses the equivalent fitting ‘K’ factor method to model the flow and pressure loss through a control valve where a Cv flow coefficient is used to specify the control valve characteristics A change to the pipe diameter would result in a change to the value of the equivalent fitting ‘K’ factor Pipe Flow Expert re-calculates the equivalent fitting ‘K’ factor for the current pipe diameter and the fluid density at the start of the solution calculation The calculation helper provided on the Cv component dialog uses the flow rate and pressure loss entered by the user, together with the current fluid density to calculate a Cv value to match the specified requirements Cv = 0.865 Kv (or more accurately Cv = 0.86497767 Kv) Kv Flow Coefficients: A Kv flow coefficient specifies the amount of water at 20°C (68 °F) in m /hour that will flow through a valve and produce a 1.0 bar pressure drop Thus a Kv flow coefficient of 10 indicates that a 1.0 bar pressure drop will occur with a 10 m /hour of water throughput through the valve The Kv flow coefficient of a control valve can be calculated from the flow rate and the pressure drop through the valve The density of the liquid in kg/m must also be used in the calculation Where: Kv = flow coefficient Q = flow rate in m /hr ∆P = pressure loss in bar across the valve D = the density of the fluid in kg/m 1000 = the density of water in kg/m The usual arrangement of the formula for calculation of Kv is shown above It can be seen that this formula is similar to the one which is used for calculation of Cv values With a known Kv flow coefficient, the above formula can be re-arranged to calculate the pressure loss for a particular flow rate thus: Where: Kv = flow coefficient Q = flow rate in m /hr ∆P = pressure loss in bar across the valve D = the density of the fluid in kg/m 1000 = the density of water in kg/m The pressure loss through a fitting or valve may also be calculated from: 180 Pipe Flow Expert User Guide Where: h fluid = head of fluid in meters K = flow coefficient of a valve or fitting V = fluid velocity entering the fitting in m/s g = acceleration due to gravity in meters/sec also Where: P = pressure in bar h fluid = head of fluid in meters D = density of fluid in kg/m g = acceleration due to gravity in meters/sec When a pipe diameter is known it is possible to establish a flow velocity from the Kv flow coefficient in m /hr for a bar pressure drop Thus it is possible to calculate an equivalent fitting ‘K’ factor which will produce the same pressure loss as the control valve Kv rating Pipe Flow Expert uses the equivalent fitting ‘K’ factor method to model the flow and pressure loss through a control valve where a Kv flow coefficient is used to specify the control valve characteristics A change to the pipe diameter would result in a change the matching equivalent fitting ‘K’ factor Pipe Flow Expert re-calculates the equivalent fitting ‘K’ factor for the current pipe diameter and the fluid density at the start of the solution calculation The calculation helper provided on the Kv component dialog uses the flow rate and pressure loss entered by the user, together with the current fluid density to calculate a Kv value to match the specified requirements 1.000 Kv = 1.156 Cv The user should be aware that the Cv or Kv flow coefficient specifies the flow rate of water for a particular pressure loss When the fluid density is greater or less than water, a different flow rate will be required to produce a 1.00 psi or a bar pressure loss through the valve CAUTIONS: Choked Flow: If the fluid is a gas and the pressure drop exceeds 50% of the inlet pressure to the valve, the flow will become choked and it will not be possible achieve the calculated flow rate Pipe Flow Expert does not model changes in the gas characteristics due to pressure or temperature changes To correctly model the pressure drop for the entered Cv or Kv value the density of the gas used in the calculation must be the density of the gas at the outlet of the valve/component Calculation Theory and Method of Solution 181 In effect this means that the fluid data for the fluid zone associated with the control valve must be defined for the approximate pressure condition at the outlet of the valve/component The pressure drop for the gas flow rate through the valve, based on the entered Cv or Kv flow coefficient and the fluid zone density in the pipe will be calculated The calculated pressure drop accounts for the effect of the expansion of the gas through the valve since using the approximate fluid density of the gas at the valve outlet (as specified in the fluid zone associated with the pipe) during calculation of the solution, caters for this characteristic If the fluid zone associated with the control valve does not represent the pressure condition at the outlet of the valve/component, it may be necessary to use an adjusted Cv (or Kv) value for valve selection to take in to account the effect of the gas expansion The adjusted Cv (or Kv) value should be based on the Cv or Kv formula for sub critical gas pressure drop A simplified version of the Cv formula for sub critical gas pressure drop is shown below: Where: Cv = flow coefficient SCFH = flow rate in ft /hr (NTP) Dn = the gas density in lbs/ft at 0.00 psig o F = gas temperature ∆p = pressure loss in psi absolute po = valve outlet pressure in psi absolute A simplified version of the Kv formula for sub critical gas pressure drop is shown below: Where: Kv = flow coefficient Q = flow rate in m /hr (NTP) Dn = the gas density in kg/m at 0.00 barg o C = gas temperature ∆p = pressure loss in bar absolute po = valve outlet pressure in bar absolute Please refer to an appropriate text book for a more detailed formula to take account of piping geometry or gas compressibility, should this be necessary 182 Pipe Flow Expert User Guide Control valve selection: The Cv (or Kv) flow coefficient of a control valve is usually stated for the fully open flow condition The Cv (or Kv) flow coefficient will be less when the valve is partly closed In an actual system it is important to select a control valve which has an appropriate Cv (or Kv) flow coefficient for the actual valve position that will be used A control valve that is too small or too large will never be able to provide the correct control in a system Most control valve manufactures recommend that you should select a valve where the required Cv (or Kv) value falls between 20% – 80% of the port opening Some control valve manufactures recommend that an allowance of 30% should be added to the calculated Cv (or Kv) flow coefficient to obtain the minimum full flow Cv (or Kv) flow coefficient rating which the selected valve should have (when fully open) Please check your control valve selection with the control valve manufacturer Flow Control Valves Flow Control Valves allow the user to set a flow rate in a particular pipe Pipe Flow Expert removes the pipe from the system and sets an Out-flow demand at the ‘From node’ and an equal In-flow demand at the ‘To node’ Thus the pipe is replaced by these flow demands while the system is being solved No other pipe which connects to a pipe with a Flow Control Valve fitted can contain a control valve (FCV, PRV or BPV) Figure 116 Flow Control Valve replacement The pressure difference between the ‘From node’ and the ‘To node’ must equal the pressure loss introduced by the flow control valve plus the pressure loss that the flow in the pipe will produce, plus the pressure loss that any other component on the pipe produces The system balance will be maintained when the pipe is reinstated along with the pressure loss introduced by the flow control valve If the pressure difference between the ‘From node’ and the ‘To node’ is not great enough then the pressure loss in the pipe and the flow control valve pressure loss cannot be set A warning will be displayed that the pressure in the pipe is not sufficient to deliver the set flow Calculation Theory and Method of Solution 183 Pressure Reducing Valves Pressure Reducing Valves allow the user to set a pressure at the node downstream of the valve (i.e at the end of the pipe) The pressure reducing valve (PRV) introduces an additional pressure loss in the pipe to control the pressure at the node downstream of the valve to the value specified by the user A pipe with a Pressure Reducing Valve fitted cannot have a tank or pressure demand set on either end No other pipe which connects to a pipe with a Pressure Reducing Valve fitted can contain a control valve (FCV, PRV or BPV) Pipe Flow Expert removes the pipe from the system and sets the pressure at the downstream node (P2) by replacing it with an appropriately defined tank The tank elevation is set to equal the node elevation, the liquid level is set to zero and the fluid surface pressure is set to the pressure reducing valve setting At the upstream node, an out-flow demand is then set equal to the flow from P2 Hence the pipe is replaced by a tank at the downstream node and an out-flow at the upstream node while the system is being solved The outflow at the upstream node must equal the flow rate from the downstream node that is now represented by the tank Figure 117 Pressure Reducing Valve replacement The pressure difference between the upstream node P1 and the downstream node P2 must equal the pressure loss through the pipe, fittings and any components on the pipe plus the pressure loss introduced by the PRV The pressure balance is then maintained after the system is solved, when the pipe is reinstated along with the pressure loss introduced by the pressure reducing valve MODES OF OPERATION: A PRV can operate under three different conditions: (1) regulating, (2) fully closed, and (3) fully open How the valve operates depends on the defined set pressure value for the valve The fully open and fully closed positions represent the extreme operations of the valve Each of the valve positions is described below: (1) Regulating The valve maintains the downstream pressure to the set value by introducing a pressure loss across the valve, thus throttling the flow rate through the PRV (2) Fully Closed This mode of operation occurs if the valve’s set pressure is less than the pressure downstream of the valve for the case where the valve is closed When this occurs in an actual pipe system, the flow through the PRV reverses and the PRV acts as a check valve, closing the pipe In PipeFlow Expert, this method of operation is detected and reported but the system is not then solved for this scenario The user must decide if this method of operation is what they intended and if so then they can close the pipe and continue to solve the system (3) Fully Open This mode of operation occurs if the valve’s set pressure is greater than the pressure upstream of the valve for the case where the valve is fully open When this occurs in an actual pipe system, the PRV maintains a fully open position and it has no effect on the flow conditions (except to add a frictional loss through 184 Pipe Flow Expert User Guide the valve) In PipeFlow Expert, this method of operation is detected and reported But the system is not solved because the differential pressure across the valve would have to be negative, i.e the valve would be acting like a pump rather than a pressure control Pipe Flow Expert will only solve a system when the PRV is operating in Regulating mode AVOIDING PRV OPERATION PROBLEMS: In general, PRV operation problems can be avoided by finding the valve’s pressure regulating range and specifying the valve’s set pressure to a value within this range, such that the mode of operation is ‘Regulating’ First, solve the system without the PRV control and note the pressure at the node downstream of the pipe which previously contained the PRV This is the maximum pressure the PRV can be set to (i.e it is equivalent to finding the valve’s inlet pressure for the case where the valve is fully open) Secondly, solve the system after closing the pipe that contains the PRV and note the pressure at the node downstream of the closed pipe This is the minimum pressure the PRV can be set to (i.e it is equivalent to finding the pressure downstream of the valve for the case where the valve is fully closed) Back Pressure Valves Back Pressure Valves allow the user to set a pressure at a node upstream of the valve (i.e at the start of the pipe) The back pressure valve (BPV) introduces an additional pressure loss in the pipe to control the pressure at the node upstream of valve to the value specified by the user A pipe with a Back Pressure Valve fitted cannot have a tank or pressure demand set on either end No other pipe which connects to a pipe with a Back Pressure Valve fitted can contain a control valve (FCV, PRV or BPV) Pipe Flow Expert removes the pipe from the system and sets the pressure at the upstream node (P1) by replacing it with an appropriately defined tank The tank elevation is set to equal the node elevation, the liquid level is set to zero and the fluid surface pressure is set to the back pressure valve setting At the downstream node, an in-flow demand is then set equal to the flow into the upstream node P1 Hence the pipe is replaced by a tank at the upstream node and an in-flow at the downstream node while the system is being solved The in-flow at the downstream node must equal the flow rate into the upstream node that is now represented by a pressurized tank Figure 118 Back Pressure Valve replacement The pressure difference between the upstream node P1 and the downstream node P2 must equal the pressure loss through the pipe, fittings and any components on the pipe plus the pressure loss introduced by the BPV The pressure balance is then maintained after the system is solved, when the pipe is reinstated along with the pressure loss introduced by the pressure reducing valve Calculation Theory and Method of Solution 185 MODES OF OPERATION: A BPV can operate under three different conditions: (1) regulating, (2) fully closed, and (3) fully open How the valve operates depends on the defined set pressure value for the valve The fully open and fully closed positions represent the extreme operations of the valve Each of the valve positions is described below: (1) Regulating The valve maintains the upstream pressure to the set value by introducing a pressure loss across the valve, thus reducing the flow rate through the BPV (2) Fully Closed This mode of operation occurs if the valve’s set pressure is greater than the pressure upstream of the valve for the case where the valve is closed When this occurs in an actual pipe system, the flow through the BPV reverses and the BPV acts as a check valve, closing the pipe In PipeFlow Expert, this method of operation is detected and reported but the system is not then solved for this scenario The user must decide if this method of operation is what they intended and if so then they can close the pipe and continue to solve the system (3) Fully Open This mode of operation occurs if the valve’s set pressure is less than the pressure downstream of the valve for the case where the valve is fully open When this occurs in an actual pipe system, the BPV maintains a fully open position and it has no effect on the flow conditions (except to add a frictional loss through the valve) In PipeFlow Expert, this method of operation is detected and reported but the system is not solved because the differential pressure across the valve would have to be negative, i.e the valve would be acting like a pump rather than a pressure control Pipe Flow Expert will only solve a system when the BPV is operating in Regulating mode AVOIDING BPV OPERATION PROBLEMS: In general, BPV operation problems can be avoided by finding the valve’s pressure regulating range and specifying the valve’s set pressure to a value within this range, such that the mode of operation is ‘Regulating’ First, solve the system without the BPV control and note the pressure at the node upstream of the pipe which previously contained the BPV This is the minimum pressure the BPV can be set to (i.e it is equivalent to finding the pressure at the valve outlet for the case where the valve is fully open) Secondly, solve the system after closing the pipe that contains the BPV and note the pressure at the node upstream of the closed pipe This is the maximum pressure the BPV can be set to (i.e it is equivalent to finding the pressure at the valve inlet for the case where the valve is fully closed) Pumps (with Flow versus Head Curve) The user is able to enter flow rate and head loss information about a pump which is to be used in the pipeline system Pipe Flow Expert generates a performance curve for the pump to allow the pump performance to be modeled as part of the pipeline system Fixed Flow Rate Pumps The user is able to elect to enter a fixed flow rate for a pump This situation may occur when the natural flow distribution to different parts of the network has to be determined, or when the system has a variable speed pump that has been set to produce a set flow rate The Fixed Flow Rate Pump is modeled in a similar manner to the Flow Control Valve described above Pipe Flow Expert removes the pipe on which the pump is mounted and sets an Out-flow demand at the ‘From node’ and an equal In-flow demand at the ‘To node’ The pipe and the pump are replaced by these flow demands while the system is being solved 186 Pipe Flow Expert User Guide Figure 119 Fixed Flow Rate Pump replacement Since the head pressure provided by the pump is unknown, the system balance cannot be ‘tuned’ by iterating along the pump performance curve For this reason it is not possible to include pressure control devices such as flow control valves on all outlet paths through the system when a fixed flow rate pump has been selected (this would result in an over-controlled system) Fixed Head / Pressure Rise Pumps The user is able to elect to enter a fixed head or pressure rise for a pump This situation may be useful when trying to estimate the pump head required to produce the flow distribution to different parts of the network, where a pump flow versus head curve has not be established The flow rates would be set by flow control valves on the outlet legs The minimum pump head would be determined by subtracting the smallest pressure introduced by the flow control valves from the fixed head supplied by the pump Net Positive Suction Head available Pipe Flow Expert is able to calculate the pressure available at a pump inlet This pressure will change if the mounting position of the pump along a pipe is changed The vapor pressure of the fluid being pumped is subtracted from the pump inlet pressure to obtain the Net Positive Suction Head available The NPSHa must be higher than the pump manufacturer’s NPSHr (Net Positive Suction Head requirement for the flow rate) in order to prevent gas bubbles forming in the fluid Two Phase Flow Pipe Flow Expert is not able to model two phase flow, such as gas/liquid mixtures When two different fluids are mixed together it is possible that two-phase flow may occur at some point in a system Pipe Flow Expert does not calculate the pressure drop for two-phase flow Two-phase flow can produce an extremely high pressure drop many times greater than the pressure drop of either individual fluid The user should make due allowance for the two-phase flow pressure drop by using a component to add an appropriate additional pressure loss Slurries Slurries which have a constant density and a constant viscosity are able to be modeled, provided the minimum velocity to keep the solids in suspension is maintained throughout the pipeline system The density and viscosity of the slurry mixture must be entered as the fluid data Working with Compressible Fluids 187 Working with compressible fluids Pipe Flow Expert has been designed for the analysis of pipeline systems using the Darcy-Weisbach equation to calculate friction loss The Darcy-Weisbach equation is normally applicable to incompressible Newtonian fluids, since the density of these fluids can be considered to be constant The system calculations not take account of any compression or expansion of the fluid that may occur due to pressure changes in the fluid and therefore the results obtained for compressible fluids may only be acceptable under certain conditions It is however common practice for the Darcy-Weisbach equation to be used to calculate the friction losses for compressible fluids within a pipeline system, if certain constraints about the system being modeled are understood It is up to the pipe systems engineer to be familiar with good engineering practice and to use their own judgment about the accuracy of results for a system that contains a compressible fluid Considerations when using compressible fluids For systems that contain compressible fluids the following should be noted: The density of each fluid zone in the system must reflect the density of the compressed fluid condition in that fluid zone The mass flow rates entering the system and the mass flow rates leaving the system must be balanced Normally In-Flow or Out-Flow values are entered using a mass flow rate units, such as lb/sec, lb/min, lb/hour, kg/sec, kg/min or kg/hour, for a system which involve compressible fluids Where volumetric In-Flow rates entering the system have to be used these values must be entered as the ‘actual’ flow rate of the fluid for that particular fluid zone applicable to the pipe from which the fluid will enter, i.e the flow rate of the fluid must be based on the density of the fluid zone (and not on the uncompressed volumetric flow rate of the fluid) Where volumetric Out-Flow rates leaving the system have to be used these values must be entered as the ‘actual’ flow rate of the fluid for that particular fluid zone applicable to the pipe from which the fluid will leave, i.e the flow rate of the fluid must be based on the density of the fluid zone (and not on the uncompressed volumetric flow rate of the fluid) The pressure at all In-Flow points for an individual fluid zone must be the same to the degree that the pressure does not change the volume and density of the fluid zone significantly Devices which change the volume/density of the fluid should not be included as part of the system analysis Pipe Flow Expert uses a constant value for the compressible fluid density throughout each individual fluid zone in the pipeline system Where volumetric flow rates are used to specify the In-Flows and Out-Flows to the system, the individual density for each fluid zone is used to convert from volumetric flow rate units to the mass flow rate units used internally by Pipe Flow Expert The calculations are performed using the mass flow rates to achieve mass flow rate continuity and balance within the pipeline system The results are then converted back to the appropriate volumetric units for each pipe, based on the fluid zone data associated with the pipe The effects of pressure changes and temperature changes on the fluid density are not modeled 188 Pipe Flow Expert User Guide If the calculated pressure drop in an individual fluid zone in the system is less than 10% of the pressure at the compressible fluid entry points into the individual fluid zone, then a reasonable accuracy of the results may be expected If the calculated pressure drop in an individual fluid zone in the system is greater than 10% but less than 40% of the pressure at the compressible fluid entry points into the individual fluid zone then the Darcy-Weisbach equation will give a reasonable accuracy provided that the calculations are repeated using the average density of the individual fluid zone Note 1: The Fluid density at the compressed fluid condition can be calculated using the normal density of the compressible fluid and the fluid pressure Compressed fluid density = Normal fluid density x (Fluid pressure + Atmospheric pressure) /Atmospheric pressure Example: If a volume of 10 m³ of air at normal temperature and pressure is compressed to bar g The Fluid density would be: 1.2047 x (6.000 + 1.01325) / 1.01325 = 8.3384 kgs/m³ Note 2: The Actual flow rate of the fluid at the compressed fluid condition can be calculated using the uncompressed volume of the fluid and the fluid pressure Actual flow rate = Uncompressed fluid volume x Atmospheric pressure (Fluid pressure + Atmospheric pressure) Example: If a flow of 10 m³/s of air at normal temperature and pressure is compressed to bar g the Actual flow rate would be: 10 x 1.01325 / (6.000 +1.01325) = 1.445 m³/s Glossary Glossary Term Absolute pressure Atmosphere Centipoise Centistokes Colebrook-White equation Darcy-Weisbach equation Demand flow Demand pressure Discharge Dynamic viscosity Friction factor Elevation End pressure Fixed pressure Fluid head Gage pressure Hydraulic grade line in Hg K value Kinematic viscosity Moody diagram mm Hg NPSHa NPSHr Pressure loss Pump head Relative roughness Reynold’s number Supply Vapor pressure Viscosity Description Pressure measured with respect to zero pressure A standard atmospheric pressure of 1.01325 bar a or 14.696 psi a -3 Absolute viscosity of a fluid expressed in Pa • s x 10 -6 Kinematic viscosity of a fluid expressed in m²/s x 10 Note: Pipe Flow Expert requires fluid viscosity to be entered in Centipoise An equation used to calculate accurate friction factors from the internal diameter and internal roughness of a pipe and the Reynold’s number for the flow conditions An equation used to calculate the frictional head loss due to fluid flow from the friction factor, the length and diameter of the pipe, the velocity of the fluid and the gravitational constant The In-Flow entering the system or the Out-Flow leaving the system The pressure at a point of exit from the system Out-Flow leaving the system The absolute viscosity of a fluid A factor to be used in the Darcy-Weisbach equation Either calculated from the Colebrook-White equation or read from the Moody diagram The height above sea level of a node or tank The pressure at a point where fluid leaves the system A static pressure loss which is independent of the flow rate The resistance to flow expressed in height of fluid as a motive force Pressure measured with respect to atmospheric pressure The pressure at a point in the system expressed in height of fluid plus the elevation above sea level of the node or the tank Height of a column of mercury in a barometer expressed in inches Coefficient of frictional loss through valve or pipe fittings The absolute viscosity of a fluid divided by the fluid density A graphical representation of the relationship between Reynold’s number, relative roughness and Friction factor Height of a column of mercury in a barometer expressed in millimeters Net Positive Such Head available Net Positive Such Head requirement The friction loss due to fluid flow expressed in fluid head or Gage pressure The motive force developed by a pump expressed in height of fluid (Pump performance graphs usually show pump head for water) A dimensionless number expressing the internal roughness of a pipe divided by the internal diameter of a pipe A dimensionless number derived from the fluid velocity, the internal diameter of the pipe and the Kinematic viscosity of the fluid In-Flow entering the system The absolute pressure at which a liquid will start to evaporate A measure of a fluid‘s resistance to flow See absolute viscosity and Kinematic viscosity 189 190 Pipe Flow Expert User Guide Index pfco files, 95 pfpm files, 103 Adding Text Items, 113 Adding Text to the Drawing, 113 back pressure valves, 184 adding, 102 understanding, 102 balanced flow state, 175 BPV adding, 99 Calculating and Solving calculating, 125 calculating pipe system results, 124 Calculation, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170 calculation theory, 136, 171 Change attributes of more than one node, 69 Change attributes of more than one pipe, 68 Change the system view, 58 Changing the fluid Density and Viscosity, 73 choosing item labeling, 62 choosing pipe drawing defaults, 64 choosing system units, 63 Choosing units, 61 Colebrook-White Formula, 172 component pressure losses pfco file, 95 adding, 89 based on a data curve, 95 deleting, 122 fixed, 95 more than one on a pipe, 95 saving data to a file, 95 viewing and modifying, 117 components adding, 95 pressure loss, 95 understanding, 95 Compressed fluid condition Actual flow rate, 188 fluid density, 188 compressible fluids, 187 considerations, 187 computer minimum requirements, 14 Configuration Options dialog Calculations tab, 51 Default Values tab, 47 Labelling tab, 45 Units tab, 46 Configuration Options screen, 44 configuring calculation parameters, 71 imperial units, 61 metric units, 61 results, 124, 128 units, 63 control valves deleting, 123 Copying between drawing, 120 Create a PDF Report, 134 creating pipe systems, 56 Creating a system, 152 Cv flow coefficient, 177 Cv Flow Coefficient, 39 Cv Flow Coefficients, 97 Cv Value, 177 Cv Values, 97 Darcy-Weisbach Formula, 173 Daxesoft Ltd contacting, 17 Defining Fluid Zones, 73 demand flows adding, 81, 109 deleting, 122 understanding, 109 viewing and modifying, 117 demand in-flows adding, 109 demand out-flows adding, 109 demand pressures adding, 111 deleting, 121 understanding, 111 viewing and modifying, 117 Documentation menu, 23 Drawing menu, 22 Drawing pane, 43 cutting, copying, and pasting nodes, 118 inverted view, 116 mirror view, 115 moving components, 117 panning pipe system, 115 undo and redo functions, 120 view whole of the pipe system, 115 zoom in, 114 zoom out, 114 Edit menu, 20 end pressure See demand flows, See demand flows Index End Pressure Data, 31 Example Systems Example 01, 137 Example 02, 138 Example 03, 139 Example 04, 140 Example 05, 141 Example 06, 142 Example 07, 143 Example 08, 144 Example 09, 145 Example 10, 146 Example 11, 147 Example 12, 148 Example 13, 149 Example 14, 150 Example 15, 151 Example 16, 152 Example 17, 157 Example 18, 158 Example 19, 159 Example 20, 160 Example 21, 161 Example ISO 01, 162 Example ISO 02, 163 Example ISO 03, 164 Example ISO 04, 165 Example ISO 05, 166 Example ISO 06, 167 Example ISO 07, 168 Example ISO 08, 169 Example ISO 09, 170 FCV adding, 99 File menu, 19 fitting head loss, 173 fittings adding, 89 adding pressure loss, 89 adding to the database, 91 calculated K value, 91 deleting, 122 viewing and modifying, 117 Fixed flow rate pump Limited application, 107 flow control valves, 182 adding, 101 understanding, 101 flow controls viewing and modifying, 117 fluid adding to the database, 76 defining for a fluid zone, 75 viscosity, 171 fluid flow states, 171 Fluid menu, 21 Fluid Zones, 73 fluids compressible working with, 187 friction factors, 172 Friction Losses, 172 Gas data adding to the database, 77 Help menu, 24 hydraulic grade line energy grade line, 174 imperial units, 61, 63 Interface and Menus, 18 Isometric Mode Toggle, 58 Isometric System Options, 56 Join Point Data, 32 join points adding, 80 adding demand flows, 81 deleting, 121 viewing and modifying, 117 K factor fitting head loss calculation, 173 Keyboard shortcuts, 28 Kv flow coefficient, 177 Kv Flow Coefficient, 39 Kv Flow Coefficients, 97 Kv Value, 177 Kv Values, 97 License menu, 23 loops nodes pipes, 175 Menu bar, 18 metric units, 61, 63 Microsoft Excel, 131 minimum computer requirements, 14 Moving a pipe to link at a new position, 120 net positive suction head, 186 New pipe system creating, 56, 57 Node pane, 29 for demand pressures, 31 for join points, 32 for tanks, 30 Node Types, 29 Node Updates Tab, 49 nodes adding, 78, 80 cutting, copying, and pasting, 118 deleting, 121 viewing and modifying, 117 PDF Report of System Results, 134 Pipe Finding a pipe or node, 115 191 192 Pipe Flow Expert User Guide Pipe diameter data dialog, 35, 47, 64 for material, 35 for size, 37 Pipe features, 34 Pipe fitting friction coefficients dialog, 38 Pipe Flow Expert about, 13 Pipe Pane, 33 pipe system adding a Fixed Flow Rate pump, 106 adding a Fixed Head / Pressure Rise pump, 107 adding a pump, 103, 104 adding back pressure valves, 102 adding components, 95 adding control valves, 99 adding demand flows, 81, 109 adding demand pressures, 111 adding fittings and valves, 89 adding flow controls, 101 adding join points, 80 adding pipes, 82 adding pressure Reducing Valves, 101 adding tanks, 78 calculating, 124 configuring results, 128 defining fluid for a fluid zone, 75 deleting components, 120 Emailing a screen image, 60 exporting results, 131 inverted view, 116 mirror view, 115 modifying, 114 moving components, 117 panning, 115 printing, 59 redesigning, 132 saving, 57 Saving a screen image, 60 saving as an enhanced metafile, 60 saving results, 130 sending via e-mail, 59 tanks, 78 view whole of the pipe sytem, 115 viewing, 114 viewing results, 130 Pipe System deleting a group of items, 121 pipe systems creating, 56 PipeFlow.co.uk contacting, 17 pipes adding, 82 adding materials to the database, 85 adding sizes to the database, 85 defining material, 83 defining size, 83 deleting, 121 Preventing backflow in a pipe, 88 reversing pipe flow, 86 shutting off a pipe, 86 Use as default pipe feature, 88 Using the pipe sub-menu while drawing, 87 viewing and modifying, 117 pressure reducing valves, 183 adding, 101 understanding, 101 printing pipe systems, 59 pump data and graphs, 106 Properties of Mixed Fluids, 74 PRV adding, 99 Pump Data dialog, 41 pumps pfpm file, 103 adding, 103, 104 adding a pump curve, 105 adding Fixed Flow Rate, 106 adding Fixed Head Pump, 107 deleting, 123 printing data and graphs, 106 pump curve graph, 106 saving data to a file, 103 viewing and modifying, 117 Pumps example pumps, 108 Fixed flow rate, 185 Fixed Head / Pressure Rise Pumps, 186 Performance Curve, 185 redo function, 120 Registration and Licensing Information, 15 results calculating, 124, 125 configuring, 128 exporting, 131 saving, 130 viewing, 130 Results Colors Selection, 70 Results Colors Tab, 50 Results dialog, 124 Results Printing using PDF Report, 134 Results tables, 53 ResultsLogForm dialog, 124 Reynolds number, 172 Rotating a group of items, 119 Selected Area zoom in, 114 Set Component Pressure Loss dialog, 39 Set Control Valve dialog, 40 Set Flow Demands dialog, 33 Setting System Options, 61 slurries, 186 solving a pipe system, 125 Step, 152 Index system calculation tolerances, 177 components, 177 Tank Node Data, 30 tanks adding, 78 deleting, 121 info, 78 viewing and modifying, 117 theory calculation, 136, 171 tool bar buttons, 25 Tools menu, 23 total pressure loss, 174 two phase flow, 186 Two phase flow additional pressure loss, 74 undo function, 120 Units menu, 21 unknown values, 176 valves adding, 89 Viewing and Modifying System Components, 117 Viewing and Modifying System Data, 116 Viewing Individual Results, 54 Walkthrough, 152 zoom function, 114 193 […]… version of the software) Contacting PipeFlow.co.uk Email: [email protected] Internet: http://www.pipeflow.co.uk UK Telephone: +44 (0)1625 509142 USA Telephone: +1 650-276-3569 +1 650-276 -FLOW PipeFlow.co.uk is a trading name of Daxesoft Ltd (U.K Registered Company) Additional PipeFlow.co.uk Products Pipe Flow Wizard – “What if?” Calculations for Liquids and Gases Pipe Flow Wizard is able to perform four… Welcome to Pipe Flow Expert Pipe Flow Expert is designed to help today’s engineers analyze and solve a wide range of problems where the flow and pressure losses throughout a pipe network must be determined The Pipe Flow Expert program will allow you to draw a complex pipeline system and analyze the features of the system when flow is occurring Pipe Flow Expert calculates the balanced steady flow and… features of a pipe use the Diameter and Material buttons to access the selection dialogs Pipe Flow Expert allows fittings and valves, components, flow control valves and pumps to be added to a pipe The selection dialogs to add or change the data for these items can be accessed by clicking on the appropriate button in the pipe pane 34 Pipe Flow Expert User Guide Pipe Features Figure 17 Pipe pane and Pipe Sub-menu… cursor Click on a node in the Drawing pane where you want to set a demand flow Use the Flow demands dialog to set the Inflows or Out-flows at the selected node công tắc đóng/mở ống Toggle to Open/Close a Pipe – Select the open/close pipe cursor Click on a pipe in the Drawing pane where you want to close a pipe or to re-open a pipe that has been closed previously Add Text – Add Free text labels to the… calculate: • Pressure Drops • Flow Rates • Size of Internal Diameters • Pipe Lengths Pipe Flow Wizard will perform calculations for individual pipes Pipe Flow Wizard will calculate results for LIQUIDS or COMPRESSED GASES A Fluid Database is included with viscosity and density of common fluids Flow Advisor – for Channels and Tanks Flow Advisor may be used to estimate water flow rate from various shaped… items added to the pipe currently selected in the Drawing pane Diam? Display the Pipe Diameter Data Dialog for Sizes Material Display the Pipe Data Dialog for Materials More… Opens the pipe sub menu which provides further options to: Re-Open / Close Pipe Reverse Pipe Direction Prevent Backflow – On / Off Move / Unlink end of Pipe Use Pipe Values for Drawing (default for the next pipe to be drawn) Change… Sub-menu Feature Description Pipe Identification Number Use the Pipe Drop Down List to select a pipe or to scroll through each of the pipes in the pipe system Name The name of the pipe currently selected in the Drawing pane Use the Name field to edit the pipe name Length The length of the pipe currently selected in the Drawing pane Use the length field to change the length of the pipe Internal Diameter The… The pipelines may vary in size and nature and will usually involve changes in elevation from one point to another These pipeline systems may include reservoirs, pressurized tanks, pumps, valves, flow control devices, heat exchangers and other components that affect flow in the pipelines 14 Pipe Flow Expert User Guide The pipeline system is modeled by drawing the join points and the connecting pipes… of minutes 18 Pipe Flow Expert User Guide Interface and Menus This section details the different features of the Pipe Flow Expert interface For each feature, there is yếu tố an explanation, a screen shot and a table providing descriptions for each element of the feature The sections following this section provide instructions for using the Pipe Flow Expert application Figure 2 Pipe Flow Expert interface… Displays instructions that explain how to move the license from one computer to another Go to www.pipeflow.co.uk Launches an internet browser window to view the Pipe Flow web site About Pipe Flow Expert Displays a pop-up window that shows details about the software Interface and Menus 25 Tool Bar Most of the Pipe Flow Expert functions can be performed by using a button on the tool bar The ReDesign and Show

– Xem thêm –

Xem thêm: Hướng dẫn sử dụng phần mềm thiết kế đường ống Pipe Flow, Hướng dẫn sử dụng phần mềm thiết kế đường ống Pipe Flow,