Monday, July 30, 2012

Future of Operator Training from Invensys presented at ACHEMA

See Norbert Jung of Invensys go through his booth at ACHEMA

Case Study in PIPEPHASE

The case study feature of PIPEPHASE can be utilized to study the effect of parameters such as Inside diameter, Elevation Change, Pipe roughness, Heat transfer coefficient, Source flowrates, Pressure drop correlations et cetera on the pressure drop:
  1. Run and converge a simulation model in PIPEPHASE
  2. Go to Special Features from the Tool bar and select Case Study
  3. Tick “Perform Case Study Calculations” and click Add
  4. Give a description to the Case Study, tick on “Restore Base Case Solution” to start the calculations from the base case and click Add
  5. Based on the type of parameter to be changed, select the appropriate “Change Item” e.g. in this case Pipe Inside Diameter is changed to 11 inches
  6. Similarly more case studies can be added for other parameters
  7. Run and view the case study results from the output file

Sunday, July 29, 2012

OTS Tip: Internal Phases Free Water

OTS Tip: Internal Phases Free Water
Guest Blogger: Kalpana Garigipati, Senior Consultant -EECOTS, Invensys Operations Management

This Tip is about “Speed improvement and better Flash stability in models where FREE_WATER internal phases are used”

When using the "FREE-WATER" internal phases option in the Thermo tab, it is advisable to check if the water mole fraction is greater than 0.0000003. Free Water flash performs better if the hydrocarbon liquid phase has a nonzero water mole fraction even if the water mole fraction is extremely small (e.g. 0.0000003 mole frac). In the real world, it is unlikely the water mole fraction is exactly zero. If water is in the component slate but exactly zero, the Free Water flash sometimes exhibits erratic behavior.

If using "FREE-WATER" internal phases in your model and there is no water in some parts of it, then a small amount of water can be added safely in sources and you should see a speed improvement (simspd) in the model.

Guest Blogger: Kalpana Garigipati, Senior Consultant -EECOTS, Invensys Operations Management

Monday, July 23, 2012

DYNSIM Product Bulletin

DYNSIM Product Bulletin

Issue:
Inconsistent propagation of component and method slate to the product streams connected to slate change and stream receive models.

The problem is present in DYNSIM 5.0 and prior versions. However, in DYNSIM 5.0, this may lead to crashes which may not have been noticed in prior versions. Issue will be fixed in the upcoming release of DYNSIM.

Description:
When a stream is connected to the product port of a slate change model, the stream is expected to inherit the slate information from the upstream slate change model. However it inherits the “default” component and method slate information for that engine.

A similar behavior can be seen for the product streams of stream receive models also. The product stream connected to a stream receive model is expected to inherit the slate information from its downstream model but does not.

A snapshot (OEV) of the mismatch in COMPSLATE and METHODSLATE of a slate change model and its product stream is shown below.

Implications:
  1. The component slate mismatch on a smaller simulation may not cause any problems (benign) but on large cases can cause the simulation to fail / crash during load or run time.
  2. Copy/Pasting such cases to another flow sheet/engine and loading the simulation will lead to multiple stream configuration errors across the simulation and may finally result in database corruption.
Workaround:
Change the slate information in the product streams of slate change and stream receive models using one of the below methods:
  1. Use the OEV to edit the offending stream(s) and set the COMPSLATE and METHODSLATE parameters to the correct values.
  2. If there are multiple slate change and stream receive models in the simulation then use the search tool to look for all such instances and correct the COMPSLATE and METHODSLATE values of their product streams.
  3. The other alternative is to use the bulk configurator tool to display the slate information for all the streams and verify the values.

Thursday, July 19, 2012

Latin America Client Conference in Venezuela is next week

INVENSYS OPERATIONS MANAGEMENT
LATIN AMERICA CLIENT CONFERENCE


JULY 25-27, 2012
LIDOTEL HOTEL, ISLA MARGARITA

Another OTS Tip

Our guest blogger, Kalpana Garigipati, is back with another great OTS tip.

Guest Blogger: Kalpana Garigipati, Senior Consultant -EECOTS, Invensys Operations Management

Generally OTS projects are built for the HMB case given by Client, and the source/feed composition is taken as constant. Ever wished if the source composition remained same as the plant data and gets updated with the actual plant composition (from Analysers/IP-21 / PI Software (also referred to as data reconciliation software)/ Inferred data from Analysers and IP-21)?

These Data Reconciliation software like IP-21/PI software lie in the secondary network of the plant network, such that it can only read and historize data for analysis and verification.
Here is the procedure for reading data from IP-21/PI software by DYNSIM:
  1. Create a CSV file with fist column as time stamp and second column with composition (Can be updated from IP-21/live data using PI software)
  2. Dynsim Feed sources can be updated using the model object CSV Text file. It is available in Icon palette àUtilities àCSV Text file (Data import)
  3. Output of Data import block goes to composition of source.
When plant data changes, inlet source composition changes, and the DYNSIM model reflects the actual plant behavior.

Guest Blogger: Kalpana Garigipati, Senior Consultant -EECOTS, Invensys Operations Management

Tuesday, July 17, 2012

Operator Training Simulator (OTS) Tip

Today we have a guest blogger, Kalpana Garigipati, who is giving us an OTS tip.

Guest Blogger: Kalpana Garigipati, Senior Consultant -EECOTS, Invensys Operations Management

During shutdown/ steady state tuning of model, it may be required to run a model overnight for:
  1. Checking stability of model (if drum levels holds, pressures are maintained)
  2. Shutdown model for cooling the process lines to ambient temperature.
When the model was left running overnight, and if it is observed that level in drum emptied when IC was taken in morning, there will be no clue when the drum emptied.
In this case, you can try this option:
  1. Tools menu --> Backtrack & IC configuration --> If model is running for overnight (approx 14-16 hours) --> Increase number of backtracks to 16
  2. Backtrack rate, increase to 3600sec (i.e) once an hour backtrack is taken if model is running in real time.
  3. If model is running at X times real time, then backtrack rate should be X*3600 sec.
  4. If the model crashes in overnight run, then the issue can be traced from the last better state by last better backtrack.
  5. Number of IC’s saved in s4m file can also be increased in the same window.
Caution:
Reset the backtrack rate to normal, after overnight run. It is betterr to have 1 min backtrack option during normal tuning, to go back to previous state for small operation mistakes made in model.

Guest Blogger: Kalpana Garigipati, Senior Consultant -EECOTS, Invensys Operations Management

Monday, July 16, 2012

How is heavy oil feedstock affecting you?

So much is being made of heavy oils today....how is it affecting your plant?

SimSci-Esscor offers a lot of innovative technology to handle heavy oils, but I would like to know how you are dealing with heavy oils.

*Blogger's Note*
17 July 2012 - I noticed that we had over 50 people view this log post, but no one contributed to the conversation by commenting. I would really like to hear your opinions. Thanks, Joe

Sunday, July 15, 2012

Using HTRI Algorithm within PRO/II for Exchanger Simulation

  1. Set up a heat exchanger model in PRO/II by defining the streams and Unit-op
  2. Go to Heat Exchanger Data Entry Window > select Use HTRI and click Setup
  3. Click on Initialize HTRI Data and wait for it to turn blue
  4. Click OK and come out of the Heat Exchanger DEW and click the button shown below. It will be observed that the Exchanger turns green in color indicating that the unit is under calculation.
  5. One can also select Initialize HTRI Data from an existing HTRI Data File.

Friday, July 13, 2012

PRO/II Optimizer

PRO/II Optimizer enables an automatic identification of the best design or operating conditions from a collection of alternatives. In the attached model an Optimizer Unit-op has been used to optimize the Feed location to minimize the Reflux ratio.
  1. Place the Optimizer Unit-op on the flowsheet and define the Objective function and Objective variable as shown below
  2. Run the model and review results, in the attached example the initial feed location is tray 18 and the optimizer changes it to a split flow to tray 13 and 14 as shown

Thursday, July 12, 2012

Relief valve rating using VISUAL FLOW

  1. Solve the model and then go to Task > Rate Network or click on the button shown below. 
  2. Select the RVs to be rated and input rating parameters. User can input an assumed back pressure or have VISUAL FLOW rigorously calculate the back pressure. Solution Tolerance can be changed for better accuracy. 
  3. Run the rating calculations by clicking OK
  4. Relief Valve rating results can be viewed in two ways –
  • Results window automatically pops up after run
  • To get these results after closing the window, go to Tasks > Reports > Rating Results
  • Tasks > Reports > Generate and View > Relief Valves > Rating
  • The results from the run will be color coded to indicate success or failure in converging that particular RV (Green = Success, Red = Failure)

Wednesday, July 11, 2012

How to model Refinery Inspection Properties in product streams

  1. Include the Refinery Inspection Properties (RIP) in the PRO/II Thermodynamics as shown below
  2. Under Define/Edit Assay click on Refinery Inspection Property and feed the curve data for the required properties
  3. Below is an example of a feed stream and the product streams from a crude column representing Aliphatic Sulfur and Mercaptan Content.

Monday, July 9, 2012

Displaying Stream Results on the Flowsheet in PRO/II

  1. Run and converge a model in PRO/II
  2. On the menu bar click on Output and select “Stream Property Table”
  3. Place the Green bordered box on the Flowsheet
  4. Double click on the Stream Property Table which will open up the Data Entry Window
  5. Select the “Property List to be used” and “Available Stream," click OK.
  6. Stream Property Table will be displayed on the Flowsheet

Friday, July 6, 2012

Drawing a Phase Envelope using the Hot Key in PRO/II


    Drawing a Phase Envelope using the Hot Key in PRO/II
    1. Click on the Phase Envelope Hot Key on the Tool Bar
    2. Select a stream for which a Phase Envelope is to be generated
    3. Tick the Full Envelope option
    4. If required, input the Liquid Mole Fractions & click on either Show Plot or Show Table to see the Phase Envelope

    Thursday, July 5, 2012

    Efficiency of Turbine Driven Compressor


      Efficiency of Turbine Driven Compressor in PRO/II
      1. Set up a Turbine using an Expander Unit-op in PRO/II and specify the outlet pressure.
      2. Set up the compressor model, link the work done by the compressor to the work of the expander and input either the Adiabatic efficiency curve or polytropic efficiency curve.
        In the above definition 5% mechanical losses have been incorporated
      3. Run the model and view the result using the Unit Operation Property table as shown below:

      Wednesday, July 4, 2012

      Attaching a Heat Exchanger to a Column

       Attaching a Heat Exchanger to a Column in PRO/II
      1. Connect the shell / tube side of the exchanger with utility stream and leave the other side unattached, as shown
      2. Specify the inlet condition for the utility stream; temperature, pressure, flowrate and composition
      3. Specify the geometry of the Exchanger, go to Products / Thermo tab > Attach to Column
      4. Specify the column to which the exchanger has to be attached and whether it is to be attached to the Condenser, Reboiler, Pumparound or Side Heater, in the example shown it is attached to the pumparound.
      5. Calculation Type can be chosen as Rating (Predictive) or stream outlet temperature

      Tuesday, July 3, 2012

      Block Diagram

      Big flowsheets can be separated into sections using the Block Diagram Unit Operation in PRO/II.
      1. Place a Block Diagram on the Flowsheet (which can be found under the GENERAL tab of the PFD palette)
      2. Connect the Feed and product stream to the Block Diagram Unit-Op which then becomes available to be used within the Block Diagram

      3. Double click on the Block Diagram and build the flowsheet


      4. The Block Diagram appears as a new tab
      5. Like other Unit-Op in PRO/II you can also rename the Block Diagram Unit-OP

      Monday, July 2, 2012

      Column with an External Reboiler



      Column with an External Reboiler in PRO/II Process Simulation Software
      1. For modeling an external reboiler for a column it is a good practice to first have the column converge with an internal reboiler.
      2. Add two pseudoproduct streams to the column e.g. “ToReb” and “BoilUp”, ToReb being the Net Liquid Flow and BoilUp being the Net Vapour Flow.
      3. Model the same column with an external reboiler and remove one specification to maintain the degrees of freedom.
      4. Provide an initial estimate for Stream 5 (see above figure) by referencing it to “ToReb”; similarly provide an initial estimate for Stream 7 by referencing it to “BoilUp”.
      5. By referencing the stream we eliminate the risk of no flow to the reboiler leading to non-convergence.
      6. A similar procedure can be followed for modeling an external condenser to a column.