LIQTHERM v7.0 – Steady State Liquid Pipeline Hydraulic Simulation

In LIQTHERM v7.0, the pipeline model may be created graphically using a drag and drop approach.
In this method, objects such as pipe segments, valves, tanks, pump stations and other devices may be selected from a toolbox and dropped on a drawing canvas.
These objects can be connected with pipe segments to form the pipeline system.
The properties of each object may be defined by double-clicking on them and entering data in the screen that is displayed.



LIQTHERM simulates the steady state hydraulics of a heated liquid pipeline with several pump and heater stations, considering heat transfer with the surrounding medium. If desired, isothermal hydraulics may also be modeled. The pipeline may be buried or portions may be above-ground. Various liquid products may be injected or stripped at locations along the pipeline.
The resultant blended liquid properties (specific gravity and viscosity) are calculated for each pipe segment at the flowing liquid temperature. Batching of different liquids can also be simulated by specifying the batch size, specific gravity and viscosity of each liquid batch. Pressure drop for each pipe segment is calculated using one of the various equations, such as Colebrook-White, Moody, Miller, MIT, T.R. Aude or Hazen-Williams.

Multiple pump stations along the pipeline may be modeled, considering pump curve data. The pump performance data (flow rate, head and efficiency) may be specified for each pump station along with the pump configuration (series or parallel). If pump curve data is not available, each pump station may be assigned an average pump efficiency for calculating the horsepower required. Calculations can be performed such that maximum allowable operating pressure (MAOP) of each pipe segment is not exceeded.
Optionally, the MAOP check may be turned off to determine the maximum pumping capability for a given pipeline and pump station configuration. Branch piping and parallel piping (pipe loops) off the main pipeline can also be modeled.

The liquid temperature, specific gravity, viscosity and the pressure profile along the pipeline at the flow rates are calculated considering heat transfer with the surroundings. Using the input values of pipe, insulation and soil thermal conductivities, heat transfer and pressure drop calculations proceed along the length of the pipeline.
The heat generated due to friction is included in the temperature calculations. For high viscosity liquids, the API method for calculating the effect of high viscosity on pressure can be included, as an option. If heaters are present, the heater duty at each heater station site is calculated based on the specified heater outlet temperature, heater efficiency and the calculated liquid temperature at the heater inlet. The total pump horsepower required at each pump station is calculated, by considering the combined pump performance based on the pump configuration.

An introductory screen shown below describes the 5 steps necessary to model a typical pipeline using LIQTHERM.

Units – This screen is used to choose English or SI units of calculation.

Options are available for different sets of units for pipeline distance, pipeline flow rates, pressures and temperatures. For pump curve data you may choose the units for flow rate and head. Note that the pipeline flow rate units need not necessarily be the same as the pump curve flow rate units.

Features of LIQTHERM

Easily models isothermal hydraulics of water lines and refined products pipelines (gasoline, diesel, etc) as well as thermal hydraulics of heated crude oil pipelines.
Most data are entered in Microsoft Excel compatible spreadsheet that results in easy editing and cut and paste operations via the Windows clipboard.

Pipe diameter, wall thickness, roughness, burial depth, insulation thickness, insulation conductivity and the ambient soil temperature can all be varied along the pipeline.

Pipe may be modeled above ground or below ground or a combination of both.

Heaters may be installed anywhere along the pipeline, to heat the liquid thereby reducing the liquid viscosity to facilitate pumping.

The required pump station locations for a grass-roots pipeline, may be quickly determined using the Locate pump stations option, under the Option menu.

At the beginning of the pipeline, a storage tank or a connection to another pipeline may be modeled, instead of a pump station.

The pipeline may have several pump stations with pumps in series or parallel at each pump station. Calculations can be performed with or without considering pump curve data. There may be a maximum of 5 pumps at each station.

Variable speed pumps, such as VFD, Turbine or Engine driven pumps may be modeled.

The amount of pump impeller trims required to minimize throttling can be calculated.

Liquid may be injected or delivered at various points along the pipeline.

A database of liquid properties may be created and updated for use with various pipelines.

Snapshot batching may be simulated. Several batches of different liquids transported in series in the pipeline can be modeled. For each batch a minimum pressure (based on the vapor pressure) may be specified, to prevent vaporization of volatile products.

A dynamic batching option is also available to model a real-time batching scenario, as described in detail below.

Drag Reduction can be simulated for specified sections of the pipeline. DRA injection in PPM or Drag Reduction % may be specified. A percent degradation of DRA may also be included for some pipe segments. Built-in algorithm for calculating PPM from % Drag Reduction and vice versa. You may specify different DRA injection rates for different products, in a batched operation.

Pressure drop calculations may be based on Moody, Colebrook, Hazen-Williams, MIT, Miller or T.R. Aude equations.

Pressure control valves and other pressure drop devices may be specified along the pipeline.

Individual pump curve data can be viewed, edited and plotted on the screen or the printer.

Automatically generates a pump curve to suit design conditions (flow rate and head), when pump curve data is not available.

The pump performance at different impeller diameters and speeds may be calculated, using the Affinity Laws.

Centrifugal pump performance may be corrected for viscosity, using the Hydraulic Institute method.

The maximum pipeline throughput for a given MAOP can be calculated for a specified pump station configuration.

Slack line conditions may be modeled for pipelines with drastic elevation changes, including pipe segments between two pump stations.

The hydraulic pressure gradient can be plotted superimposed on the pipeline elevation profile.

Pipe branches and pipe loops may be modeled. Maximum number of branches and loops is limited to 50. Each branch pipe may have up to 500 data points compared to a maximum of 1000 sets of data points for the main pipeline. The branch piping and loops may not have any pump stations. Flow injection and stripping are allowed on the branches.

The capital cost of pipelines and facilities may be calculated.

The annual operating cost of pipelines and facilities may be calculated.

The transportation tariff and annual cost of service, based on debt/equity ratio, interest rate, ROR and project life may be calculated.

The input data consists of pipeline profile (distance, elevation, pipe diameter and wall thickness, pipe roughness, MAOP), thermal conductivity data (for pipe, insulation and soil), soil temperature, burial depth of pipe (cover), liquid flow rates, specific gravity, specific heat and viscosity of each liquid at two distinct temperatures, heater station data (inlet temperature, heater outlet temperature, heater efficiency) and delivery pressure required at the end of the pipeline. All of the above properties are considered variable along the length of the pipeline. Thus the pipe roughness may be varied at specific points along the pipeline to simulate different internal conditions of pipe such as internally coated pipe versus un-coated pipe. Similarly, the pipeline may be buried for a portion of its length and the rest may be above ground. Pipe may be insulated with a certain thickness and type of insulation for a specified length, while the remaining pipe may be bare or un-insulated. The properties of the liquid, such as specific gravity, viscosity are specified at two known temperatures for determining the property versus temperature correlation. In addition, the locations of pumps and heater stations are input along with the minimum suction pressure at each pump station. If pump curves are not available, an average pump efficiency for each station is input. If pump curve data is available, efficiencies will be automatically calculated by the program.

Most data are entered in Microsoft Excel compatible spreadsheets that results in easy editing and cut and paste operations via the Windows clipboard. The spreadsheets are saved in a proprietary file format compared to the familiar .XLS file extension for Microsoft Excel. For the sample problem, pipeline profile data (distance, elevation, pipe diameter and wall thickness, pipe roughness, MAOP) is saved in a file designated as MyPipe001.TOT. All other data for the specific pipeline such as thermal conductivity data, pump and heater station data, liquid flow rate data etc. are saved in the same text file named MyPipe001.TOT. Auxiliary data such as pump curves, liquid data that may be used with other pipelines will be saved separately from the specific pipeline data. For example in the MyPipe001.TOT file they may be references to pump curves such as PUMP1.PMP, PUMP2.PMP etc. All liquid properties are stored in common Liquid Properties Database files, which may be edited and updated with new products.

Upon clicking the icon with the letter Q, the Quick Pressure Drop option screen shown opens up.

The Calculate icon will display the following screen for specifying the format of the calculated results. The program output consists of the flowing liquid temperature, specific gravity, viscosity, and the pressures along the pipeline, along with the heater duty and horsepower required at each heater station and pump station. The output report can be customized as desired. The output report may also be exported to Windows Notepad or a Microsoft Excel File.

If the input pipeline flow rate is too high for the pumps or require pipeline pressure exceeding MAOP, the program iteratively calculates the maximum pipe inlet flow possible. This feature can be turned off, if desired. LIQTHERM can be used for the design of a new pipeline or checking capabilities of existing pipelines. The hydraulic gradient showing the pipeline pressures superimposed on the pipeline elevation profile along the pipeline can be plotted. The flowing liquid temperature profile along the pipeline may also be plotted, if desired.

The calculated results are displayed on the screen, as well as saved in a disk file for later viewing or printing. A printed hard copy of the calculated results can be created simultaneously with screen output. The results may also be exported to Windows Notepad or an Excel file.

In each data entry screen, Help is available on each screen and on the status bar at the bottom of each data entry screen.

For quick economic analyses, the capital cost and operating cost for a pipeline system can be calculated. The annual cost of service and transportation tariff can also be determined for various project financing scenarios.

With AutoBatching you can simulate dynamic batching of different products pumped through the pipeline.

Input a monthly or weekly batching schedule of different products and their volumes.

Specify a simulation time, such as 100 hr, 200 hr, etc.

Specify a time interval for advancing the batches, such as 1, 2, 4 or more hours

If DRA is used, indicate drag reduction segments and input % Drag reduction (or DRA ppm), including individual %DR (or ppm) for each product batched. For example you may specify that in the pipe segment from m.p. 10 to m.p 50, the %Drag reduction is 20% for Gasoline, 30% for diesel or zero for Jet fuel.

You may also specify different minimum pressures for each product batch, such as 250 psig for propane batch or 50 psig for gasoline. LIQTHERM will automatically adjust the pipeline pressures to ensure the appropriate minimum pressure is maintained to prevent vaporization of a volatile product. During the simulation, LIQTHERM graphically depicts the batches as they move through the pipeline, as shown below:

After the Autobatching simulation, the report will show a hydraulic summary for each time step and finally an average pipeline flow rate for the simulation period. A graphic plot of how the flow rate varies with time as the different batches move thru the pipeline may also be generated as shown.

This software can be run on Windows 7 thru 10 operating systems. A minimum hard disk space of 8 GB is required for installing the program.

Technical Support:
Technical support is provided for licensed users of the software for a period of sixty(60) days from the initial purchase date. Economical Annual Technical Support plans are available after the initial 60-day period. Minor updates and maintenance releases are posted at SYSTEK’s Web site for licensed users to download free of charge. You may need to contact SYSTEK to obtain a password for downloading and installing an update from the web site. Call or email us for details of Technical Support plans.

You may purchase or lease LIQTHERM software. The minimum lease period is six months. Multi-user licenses are also available. The software is available for purchase or lease via direct download from our web site as well as via CD-ROM shipped to you in the mail. Registration is via the internet. However, only one copy may be executed at any time on one computer. We welcome comments and suggestions from users. Please give us your thoughts on how LIQTHERM can be improved further. Our goal is to make this software the most user-friendly program available for engineers.