Pipe

Related Links: Pipe - Dynamic Mode

General Description

This is used to transfer material between two units in SysCAD. Each pipe can have only one source and one destination. The user will find that a large amount of information is contained in pipe.

• In Steady State (ProBal) mode, the pipe serves as a simple link, which requires very little configuration.
• In Dynamic mode the pipe contains additional fields relating to required flows and network configuration. Please see Pipe - Dynamic Mode for more information on this data.

Enabling Sub-Models

When a pipe, or link, is inserted in a SysCAD project, it will be a 'Simple' pipe, i.e. Flow conditions into the Pipe = Flow conditions out of the Pipe. However, users may specify a pressure drop and/or enable sub-models in a pipe. The user can select the sequence in which the sub-models act, however the pressure drop is applied first. To enable sub-models the user must un-tick the 'Simplify' tickbox, as shown below:

Available Sub-Models

Evaluation Block:

1. Makeup Blocks (one or more) may be enabled in a Pipe. This allows the user to control the addition of streams such as reagents, water, air, etc to the pipe, often without having to use a PID or General controller.
2. The Reaction Block (RB) allows the user to configure any number of reactions within the pipe.
3. The Environmental Heat Exchanger Block allows the user to add or remove energy from the pipe using a number of different methods.
4. The Evaporation Block allows the user to set the evaporation of either water only or a mixture of water and all other species that are specified as both liquid and vapour.
5. The Vapour Liquid Equilibrium Block will attempt to ensure that the vapours and liquids of the selected species will be in equilibrium in the pipe. For example, if the equilibrium species is water and the pipe is at atmospheric pressure, then SysCAD will maintain the temperature at, or below, the saturated temperature of 99.97°C by evaporating water if required.
6. Discard Blocks (one or more) may be enabled in a Pipe. This allows the user to control the discarding of material from the Pipe, usually without having to use a PID or General controller. This is available in Build 138 or later.

Model Procedures

Model Procedures allows the user to implement code directly within the Pipe. The code used is almost identical to the code in pgm files.

To enable this, on the "Info" tab page tick the "Procedures" tickbox, as shown below:

Flowchart

The following shows the sequence of events if the Pipe is not simplified and any sub model options are enabled.

Model Theory

Pressure Drop Equations

Darcy Pressure Drop for slurry

$\mathbf {\mathrm {DP} = (\boldsymbol{\rho}_{all} * \mathbf g * dZ) + \left (\frac {1} {2} * \boldsymbol{\rho}_{all} * \mathit {v} \mathrm {el}^2 * (\mathrm {K} + \mathrm {K_-MinorLosses}\right) }$

where

ρall is density (Rho) of the complete mixture (all phases)

K can be specified or calculated as $\mathbf {\mathrm {K = \frac{FricFactor * TotalLength}{D}}}$

Where

D = Diam - (2 * ScaleBuildup)

TotalLength = length (L) + Fitting Length (FitL)

FricFactor can be specified or calculated as:

$\mathbf {\mathrm {FricFactor}= \mathrm{8.0} \begin{Bmatrix} \begin{bmatrix} \mathrm{-2.457*Ln} \begin{pmatrix} \mathrm{\frac{7}{Re}} \end{pmatrix} ^{0.9} \mathrm{+.27*\frac{Pipe_-Rough}{D}} \end{bmatrix}^{16} \mathrm{+\left (\frac {37530}{Re} \right)^{16}} \end{Bmatrix}^{-0.125} }$

Reynolds number $\mathbf {\mathrm{Re} = \begin{pmatrix}\mathrm{D*vel*Density}\end{pmatrix}\mathrm{/Viscosity}}$

Re has a lower limit of 1e-9.

Viscosity has a lower limit of 1e-12.

Data Sections

The Dynamic Pipe contains additional fields relating to required flows and network configuration. Only the fields shown for ProBal are described here.

Summary of Data Sections

The pipe access window may consist of a number of sections. This number may increase or decrease, based on user configuration and / or number of species.

1. Pipe-1 - The first section, contains general information relating to material flowing through the pipe, the Source and Destination units and allows the user to enable Demand. To enable the sub models (for example Reactions or Environmental Heat Exchange) in a Pipe, the user must first disable Simplify and then the Evaluation Block (EB) will be visible.
2. PC - Optional tab that is visible if EB.Solubility.On and/or EB.PhaseChange@T.On is enabled on the first tab.
3. RB - Optional tab that is visible if Reactions are enabled.
4. EHX - Optional tab that is visible if Environmental Heat Exchanger is enabled.
5. Evap - Optional tab that is visible if Evaporator is enabled.
6. VLE - Optional tab that is visible if Vapour Liquid Equilibrium is enabled.
7. MU - Optional tab, or multiple tabs if more than 1 Makeup Block is selected, Only visible if one of more Makeup Blocks are enabled in the Evaluation Block.
8. DB - Optional tab, or multiple tabs if more than 1 Discard Block is selected. Only visible if one of more Discard Blocks are enabled in the Evaluation Block. Only available in Build 138 or later.
9. Qi - This and subsequent tab pages, e.g. Qi.. and Sp, shows the properties of the inlet stream. This tab is only visible if Simplify is NOT enabled.
• This is before any Evaluation Block sub-models are evaluated (see the Flowchart above).
10. Qo - This and subsequent tab pages, e.g. Qo.. and Sp, shows the properties of the outlet stream. This tab is always visible.
• This is before any Evaluation Block sub-models are evaluated (see the Flowchart above).
11. Info tab - contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
12. MP tab - Optional tab, only visible if Procedures have been enabled on the Info tab page.
13. Links tab, contains a summary table for all the input and output streams.
14. Audit tab - contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Pipe Page

Unit Type: Pipe-1 - The first tab page in the access window will have this name.

Symbol / Tag

Input / Calc

Description

Results: Inlet Flow Conditions

MassFlow / Qm Calc The total mass of material flowing through the pipe.
VolFlow / Qv Calc The total volumetric flow through the pipe.
VolFlow / NQv Calc The normalised volumetric flow through the pipe. The volume is calculated at Normal Temperature and Pressure (NTP), default values are 25C and 101.325kPa. This is only relevant for flows containing vapours.
NTP can be specified by the user in the configuration file (see Project Configuration).
TemperatureIn / Ti Calc The temperature of the material flowing into the pipe.
Temperature / T Calc The temperature of the material flowing into the pipe.
Density / Rho Calc The density of the material flowing into the pipe.
NDensity / NRho Calc The normalised density of the material flowing through the pipe. The normalised density is calculated at Normal Temperature and Pressure (NTP), default values are 25C and 101.325kPa. This is only relevant for flows containing vapours.
NTP can be specified by the user in the configuration file (see Project Configuration).
Press_Input / Pi Calc The pressure into the pipe.

Outlet Flow Conditions

TemperatureOut / To Calc The temperature of the material flowing out of the pipe.
Press_Output / Po Calc The pressure out of the pipe.

Connections

Source_Link / SrcIO Display The tag of the source unit of the pipe, as well as the connection point, i.e. if the source is a thickener, whether the pipe is connected to the overflow or the underflow.
Destination_Link / DstIO Display The tag of pipe's destination unit, as well as the connection point.
Source_PortID / SrcTag Display The tag of the source unit of the pipe.
Destination_PortID / DstTag Display The tag of pipe's destination unit.
ConnectDescription / ConnectDesc Display A description for the pipe based on the SrcIO (pipe input) and DstIO (pipe output) fields. This is mainly used for reporting. SysCAD will copy this field into the GenDesc field IF the EqpDesc field on the Info' tab is blank.

Requirements

Configuration.Exists Display Only available in Build 137 or later. This field indicates if the pipe can be simplified. 0 = no configuration (can be simplified), 1 = configured (cannot be simplified). Types of configuration include reactions, makeups, qualities or species model configuration.
Simplify Tick Box By default this state is enabled, causing the pipe to be a 'simple' pipe with only the Qo tabs being visible. If the user wishes to set anything in the pipe or enable reactions, heat loss, etc, then this tick box must be disabled. Additional fields will then become visible and the user may set sub-models in the pipe.
Simplify.Blocked Display Only available in Build 137 or later. This field indicates if a pipe has been blocked from being simplified due to some configuration in the pipe. 1 = Simplify has been ticked but pipe is not simplified due to some configuration (Configuration.Exists = 1). 0 = Simplify is not ticked or pipe has been simplified.
Show.Qi Tick Box This tickbox is only visible if the pipe is NOT Simplified. The user may enable this to view both the Qi (flow into the pipe) and Qo (flow out of the pipe) tabs, which may be useful if the user has added reactions, heat exchange, etc to the pipe.

EB (Flow Evaluation Block)

Note This section is only visible if Simplify is Disabled.

Solubility.On Tickbox Only visible if Solubility has been defined for at least one species in the project. Allows the user to switch on any predefined solubility curve to adjust the composition of material in the unit.
PhaseChange@T.On Tickbox Only visible if Phase Change at Temperature has been defined for at least one species in the project. Allows the user to switch on any predefined phase changes at temperature in the unit.
EvalSequence Calc The sequence in which the sub models (which are part of the evaluation blocks) will be calculated. The sequence is determined by the priority selection for the individual sub-models.
Note: If the user chooses On-AutoSequence then SysCAD will determine the sequence of the sub-models. The sequence followed will be MU1, MU2, etc., RB, EHX, Evap, VLE, DB1, DB2, etc.
Makeups Input The number of Makeup Blocks required. Extra dropdown options Makeup1, Makeup2, etc will be added to allow these to be switched on and off and prioritised in relation to the other sub-models.
MakeupX List Use to enable or disable and set the sequence of the Makeup Block in relation to the other sub-models. If this is 'On' then the associated page, MUX becomes visible and may be configured.
Note: This field is only visible if the entry for 'Makeups' is greater then 0. If there is one makeup then X=1. If there are two makeups, then X=1 and X=2, etc.
Reactions List Reaction Block (RB) - Enable or disable Reactions and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, RB becomes visible and may be configured.
Note: The user does not have to configure a reaction file, even if this block is checked.
EnvironHX List Environmental Heat Exchanger (EHX) - Enable or disable Environmental Heat Exchange and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, EHX becomes visible and may be configured.
Note: The user does not have to configure an environmental heat exchange, even if this block is checked.
Evaporation List Evaporation Block (Evap) - Enable or disable the Evaporator and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, Evap becomes visible and may be configured.
Note: The user does not have to configure an evaporator, even if this block is checked.
VLEquilibrium List Vapour Liquid Equilibrium (VLE) - Enable or disable Vapour Liquid Equilibrium and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, VLE becomes visible and may be configured.
Note: This option may automatically adjust the species make-up in Qo.
Discards Input Only available in Build 138 or later. The number of discard blocks required. Extra dropdown options Discard1, Discard2, etc will be added to allow these to be switched on.
DiscardX List Only available in Build 138 or later. This can be used to switch the Discard Block (DB) on or off and prioritise it in relation to the other sub-models. If this is 'On' then the associated page, DBX becomes visible and may be configured.
Note: This field is only visible if the entry for 'Discards' is greater than 0. If there is one discard then X=1. If there are two discards, then X=1 and X=2, etc.

General Demand

Qm_Avail.Source / Src Display The mass flow available at the source, such as a Feeder or a Flash Tank. This field is only useful when Demand mode is used, either in a Feeder or as part of the Flash Train macro model.

Note This field will only be visible if ShowDemandAvail is enabled in SysCAD 9.2 - Plant Model - Settings - Demand Configuration OR SysCAD 9.3 - Plant Model - FlwSolve - Demand Configuration.

Qm_Avail.Dest / Dst Display The mass flow available for the destination.

Note This field will only be visible if ShowDemandAvail is enabled in SysCAD 9.2 - Plant Model - Settings - Demand Configuration OR SysCAD 9.3 - Plant Model - FlwSolve - Demand Configuration.

Qm_Demand.Source / Src Display The flow required at the source, ie. upstream.
Qm_Demand.Block / Blk Tickbox If this is enabled, then the Demand will be Blocked from perpetrating either up or downstream. This is used to prevent demand in a recycle and also to prevent a single unit seeing two feeders with Demand enabled. (Please see Demand for further information)
Qm_Demand.Reqd Input The user may set a required mass flow through the pipe. This flow will filter back to the source unit and the model will attempt to satisfy this flow requirement.
Note: If the pipe is connected to a Feeder, the user should enable the variable 'Demand.On' on the Feeder. The Feeder will then deliver the mass flow required by the pipe. See Demand for more information on this feature.
Qm_Demand.Dest / Dst Display Flow required at destination, i.e. downstream.

FlashTrain Demand

Ft.Qm_Avail.Source Display The mass flow available at the source.

Note This field will only be visible if ShowDemandAvail is enabled in SysCAD 9.2 - Plant Model - Settings - Demand Configuration OR SysCAD 9.3 - Plant Model - FlwSolve - Demand Configuration.

Ft.Qm_Avail.Dest Display The mass flow available for the destination.

Note This field will only be visible if ShowDemandAvail is enabled in SysCAD 9.2 - Plant Model - Settings - Demand Configuration OR SysCAD 9.3 - Plant Model - FlwSolve - Demand Configuration.

Ft.Qm_Demand.Source Display The vapour flow required at the source, eg. flash tank flash vapour.
Ft.Qm_Demand.Dest Display Flow required at destination, eg. flash vapour to the heat exchanger.

Pressure Drop

Note This section is only visible if Simplify is Disabled.

Press_Mode None There is no pressure change in the pipe.
Drop The user can enter a fixed pressure drop in the pipe. The default is 0.
Boost The user can enter a fixed pressure boost in the pipe. The default is 0.
Darcy The pressure change will be calculated using the Darcy equation.
Fixed The user can type in a fixed pressure value.
Diameter Velocity The user may specify a velocity and SysCAD will calculate a pipe diameter to give the required velocity.
Note: SysCAD does NOT calculate a pressure drop for this method.
PressDropReqd Input Allows the user to enter a pressure drop. Visible when PressMethod = "Drop".
PressBoostReqd Input Allows the user to enter a pressure boost. Visible when PressMethod = "Boost".
PressureReqd Input Allows the user to specify the outlet pressure of the pipe. Visible when PressMethod = "Fixed".
PressChange / dP Calc The calculated pressure change across the pipe, based on the method selected by the user. This value will be zero for the 'None' and 'Diameter_Velocity' methods.
PressDrop / Pdrop Calc The calculated pressure drop across the pipe, based on the method selected by the user. This value will be zero for the 'None' and 'Diameter_Velocity' methods.
This value will always have the opposite sign to dP above.
The following fields are only visible if the Diameter_Velocity method is selected.
Diam Display The estimated nominal diameter of the pipe based on the user defined Velocity.
Velocity / Vel Input The user defined target velocity, SysCAD will estimate the required Pipe diameter needed to achieve this required velocity.
The following fields are only visible if the Darcy method is selected.
Diameter / Diam Input The Inner diameter of the pipe.
ScaleBuildUp Input The build up of material inside the pipe, thus reducing the ID of pipe. For a clean pipe, this value = 0.
K_Method Calc K Calculate K from user defined values.
Define_K Calculates the pressure drop using user specified pressure drop factor.
K_Value Input / Calc The pressure drop factor: K = f * L/D. If the Define_K method is selected, this is an input, otherwise it is calculated.
The following fields are visible if Calc_K method is selected.
Length Input The actual length of the pipe.
FittingsLength Input The fittings length of the pipe.
f_Method Calc_f Calculate the friction factor from user defined values.
Define_f The user can define a friction factor (f) to be used
FricFac Input The Darcy friction factor (f). Please note this is equivalent to (4) times Fanning's friction factor. Visible if Define_f method is selected.
Viscosity Input The Viscosity of the material flowing through the pipe. Visible if Calc_f method is selected.
PipeRough Input The Pipe Roughness value. Visible if Calc_f method is selected.
ReynoldsNo / Re Calc The calculated Reynolds number. Visible if Calc_f method is selected.
FricFac Calc The calculated Darcy friction factor (f). Visible if Calc_f method is selected. Please note this is equivalent to (4) times Fanning's friction factor.
K_MinorLosses Input K value for minor pressure losses in the pipe.
PipeDeltaZ Input The overall change of height for the pipe.
Velocity / Vel Calc The velocity in the pipe.
Note: a warning will be given if the velocity in the pipe is too high. Velocity limits maybe set/adjusted via View-PlantModel-RC Tab. See Range Checks

Tear

Priority Normal SysCAD determines the priority of the stream in the network and if the stream should be a tear stream and its solving order.
First The user may force the stream order to be first in the network.
Last The user may force the stream order to be last in the network.
RqdType No Tear No manual tear is required.
Manual Tear This option is for when the user wants to influence the location of the tear stream in a recycle. This will force SysCAD to prioritise setting this pipe as a Tear stream. The system selected tear stream in the recycle loop will be reset to have no tear. It is possible to create more tears than are required. In some flowsheets, with some arrangement of controllers, it can be possible to reduce the number of iterations required to converge to a solution and/or reduce instability while converging.
Break This option is used when the user want to 'break' the stream and manually set some parameters in the stream outlet.
Type No Tear The stream has no tears or breaks.
Zero Flow Tear The stream is a Tear stream with zero flow.
System Tear SysCAD has analysed the network and determined that the stream is a Tear stream because it is part of a recycle loop and is the most efficient stream to tear.
Manual Tear The user has manually set this stream as a Tear stream.
Break The user has manually 'broken' the stream.
Flange Display The relevant flange that will have the tear status. In SysCAD each pipe is connected using flanges and these will store the tear information.
AdjQmToEstQm Tickbox If this is enabled then the mass flow from the pipe will be forced to be equal to the estimated mass flow.