Using eRCM Software - ACI Services, Inc. eRCM Software.pdfUsing either ACI’s eRCM software package (or Ajax’s eAjax software package) an engineer can create eRCM Viewer files

OPERATORS MANUAL

Rev 1.2

January 2006

ACI Services, Inc. 125 Steubenville Avenue Cambridge, Ohio 43725 Phone: 740.435.0240

Fax: 740.435.0260 Email: [email protected] Website: www.ACIServicesInc.com

Rev 1.1 ACI’s eRCM™ Manual Page 1 of 45

www.ACIServicesInc.com Phone: (740) 435-0240 Fax: (740) 435-0260

125 Steubenville Ave. Cambridge, Ohio 43725

Table of Contents Introduction..........................................................................................................................................................2 eRCM Licensing and Registration .....................................................................................................................3 General Use General/Frame Tab...................................................................................................................................4-5 Driver Options ..............................................................................................................................................6 Gas Data Tab............................................................................................................................................7-8 Cylinders Tab..........................................................................................................................................9-10 OEM Databases/User’s Database...........................................................................................11-12 Stages/Throws Tab....................................................................................................................................13 Load Steps Tab.....................................................................................................................................14-15 Analyze Model Tab ....................................................................................................................................16 Graph/Analysis Tab ..............................................................................................................................17-19 Reports Tab ...............................................................................................................................................20 How to Use Automation Option ...............................................................................................21-22 Tuning Tab............................................................................................................................................23-24 Miscellaneous Items Variable Volume Pockets...........................................................................................................................25 Current Point’s Detailed Analysis Unit Tab ........................................................................................................................................25 Stages Tab....................................................................................................................................25 Throws Tab ...................................................................................................................................26 Cylinders Tab................................................................................................................................27 Special Notes Moving files, Viewing Torque, Cut/Copy/Paste, Shortcuts, and Calculators .............................................28 Notes on Tandem Cylinders ......................................................................................................................29 eRCM Menu Structure File Menu ..............................................................................................................................................30-31 Edit Menu...................................................................................................................................................32 Options Menu........................................................................................................................................33-34 Rf Assistance .............................................................................................................................................35 Help Menu..................................................................................................................................................36 Printing Graphs.............................................................................................................................................37-38 Software License ..........................................................................................................................................39-40 Addendum: eRCM™ Data Input Notes .......................................................................................................41-45




Introduction eRCM™ is a reciprocating compressor modeling program. While specialized for the natural gas compression industry, eRCM also provides gas thermodynamics modeling for many process gases. eRCM™ allows the user to model various types of reciprocating compressors, various methods of load and flow control, provides for dynamic performance (both point and curve), provides for methodologies to tune units for the effects of pulsations, and allows users to create models (including corresponding equations) for predicting unit performance via PLCs. Using either ACI’s eRCM software package (or Ajax’s eAjax software package) an engineer can create eRCM Viewer files. ACI’s free eRCM Viewer software allows for dynamic review of individual point performance, and full map performance via multiple types of compressor curves using technology from ACI’s eCurves®. Users can print detailed reports and/or entire complements of full-color performance curves, including 3-D plots. Furthermore, other ACI software, such as eRCM Unit Staging™, eRCM Controller™, eStationFlow™, eRCM ActiveX, eRCM Points Report™, and eRCM MultiServices™ all make use of the same eRCM Viewer file format. All of these software packages are freeware. For additional order information about other ACI software for reciprocating compressors, please contact ACI at 1.740.435.0240, 9AM – 5PM EST. For specialized needs, ACI can create custom programs using your eRCM models for situations that are difficult to model in a general program, such as:

Multiple units sharing a common intercooler (IE gas from various units mixing before being compressed at the subsequent stage(s).

Dynamic sidestreams (into or out of the main stream).




eRCM Licensing and Registration eRCM is a commercial software package. Its full-use abilities are restricted to customers who purchase it. Demo Mode: Users wanting to review eRCM’s interface and abilities may install the eRCM software onto their computers, run eRCM and select DEMO. However, they will not be able to save files, print reports, and some other features will either be limited in function or disabled completely. 30 Day/Use Demo Mode: Users wanting to review eRCM’s interface and abilities in more detail, may install the eRCM software onto their computers, run eRCM, select 30-Day DEMO, and then contact ACI Services for a 30-Day Registration Number. Upon successful registration, users will have access to most (but not all) features for the shorter of 30 days or 30 runs. Licensed User Mode: Users purchasing eRCM should install the software onto their computers, run eRCM, select their company’s name from the displayed list (or select Unlisted if not listed), and then contact ACI Services for a Full Registration Number. Upon successful registration, users will have access to all commercial features. For full details about eRCM’s license agreement, read the Software License Agreement provided later in this document. Other eRCM Family Software: (All are Freeware and may be distributed without purchase or royalties to ACI)

eRCM Viewer™ – Let users review your models without needing the full eRCM software.

eRCM Points Report™ – Generate multiple performance points for one or many units. Change

something, and regenerate hundreds of points with just one click.

eRCM Evaluator™ – Compare flow abilities between different units, or different arrangements of the

same unit to determine which unit or configuration best meets your flow requirements.

eRCM MultiServices™ – Run multiple services on one unit. For example, run separate H2 and CO2

compression services on the same 4-throw compressor.

eRCM Unit Staging™ – Model complex station arrangements, such as having five units with three

distinct inlets, compress gas into four other units with two distinct outlets.

eStationFlow™ – Model a whole station of units. Enter desired flow rates, and the software will respond

with which units need to be running (and at what speeds and load steps) to deliver the desired flow.

General Use ACI Software: (All are Freeware and may be distributed without purchase or royalties to ACI)

ACI’s Mini Sizing Application – Use to size generic reciprocating compressors.

ACI’s P-V Modeler™ – Use for teaching/learning about what effects load and flow control devices have

on actual Pressure-Volume (P-V) diagrams.

eRCM Gas Model using NIST – Advanced thermodynamic model. Includes links to NIST for purchasing

their full software.




General Use General/Frame Tab

The General Data section is used for entering key information about the unit and its reference information. If you select an OEM via the O.E.M. ID, then that OEM’s list of frame and cylinders will be made available. When an OEM is selected, then eRCM attempts to model the current unit using cutoffs and prediction methodologies similar (but not necessarily exact) to the OEM. At times, this may include implementing proprietary OEM modeling equations. For units with tandem cylinders, the number of cylinders will usually be greater than the number of throws. For frames with blank throws (IE no cylinder on a particular throw), the number of throws may be greater than the number of cylinders. Most OEMs prefer users not to operate units when Suction Volumetric Efficiency is less than 30%. However, many will consent down to 17% or 15%, although they will not typically guarantee points in these regions. In general, operations are possible all the way to 0%, although 15% Vol. Eff. is usually the limit specified by API618. As the Suction Volumetric Efficiency decreases, then less volumes of cooler suction gas enter the cylinder. This causes the cylinder to heat up, which can lead to problems, especially valve degradation. Furthermore, prediction of loads and flows becomes difficult since at low volumetric efficiencies, the effects of pulsations are more dominant.




In the Frame Data section, select a frame from the provided list if applicable, or manually enter data describing the frame. You may always override any auto-entered values if your frame has been customized. In cases where the compressor needs to be derated to a lower driver speed, select the Derate Compressor link and enter the driver’s speed. This may be the case when you attach a 900-RPM motor to a frame rated at 1000 RPM. In general, a frame’s rated speed should never be up-rated without the OEM’s authorization. Note: Some users prefer to generate performance based on all of the horsepower required of the driver, while others prefer to base performance only on the horsepower actually required by the compressor. In general:

Ajax: To match eAjax’s curves, set eRCM’s Rated BHP to be the same as eAjax’s Compressor BHP Available – you can find this in the Compressor Description section of the Models/Cylinders/Coolers tab.

Ariel: To match Ariel Performance™ curves, set eRCM’s Rated BHP to be the same as the Avail. HP value found in the driver section of the Frame/Cylinder Data tab.

Dresser-Rand: To match DRSize™ curves, set eRCM’s Rated BHP to be the same as the Enter Power (BHP) value found in the Load Conditions section of the Operating Parameters options.

Gemini: To match EZ Size Pro™ curves, set eRCM’s Fixed Auxiliary Load to be the same as the Aux. HP value found via the Edit – Unit Data menu options. Also, adjust according to whether you have the Auxiliary HP option turned on in EZ Size Pro (this can be toggled on/off via their Utilities – Apply/Omit Aux. Power.)

Superior: To match Cascade™ curves, set eRCM’s Rated BHP to be the same as the Max. Available Power value found in the Limits/Torque section of the Modify Data menu option.

The Length of the Connecting Rod is only required if you plan on running full rod load calculations. In the Operating Ranges section, enter minimum and maximum values for each of the operating parameters. While minimum and maximum values may be the same for speed, torque and suction temperatures, the maximum value must be greater than the minimum value for Suction Pressure and for Discharge Pressure. If needed, you can enter a maximum value just slightly higher than the minimum value. You may enter various notes about the compressor in the Notes box. To view notes in a larger window, or to add personal notes (notes not sent when you e-mail the file), then click on the Notes about this Compressor label. This action will enlarge the notes box and also expose the personal note box.




Driver Options

Select this option to display a list of options related to the driver: List of common drivers (their speeds and maximum allowed loading), Enter data to derate unit based on speed, Enter data to derate unit based on ambient temperatures, Enter fuel data required for later prediction of fuel consumption.

Note: To apply a dynamic derating to your driver, enter select points from driver’s derate curves into the appropriate tables (Limit Load Based on Ambient Temperature, or Limit Load Based on Speed). Note: To include fuel predictions along with other compressor predictions, you will need to enter some known fuel usage at known loads and speeds. In general, you will need three fuel usage values for three distinct loads (IE at 100% load, 90% load and 75% load) when the unit it running at rated speed. And, you will need at least three additional points (IE at 100% load, 90% load and 75% load) for three other speeds different than rated speed (IE at 90% rated speed, 80% rated speed, and 70% rated speed). If you plan on including fuel prediction calculations into your PLC model, select the Display Fuel Prediction Equation button to display the equation that needs to be programmed into your PLC.




Gas Data Tab

There are various options for setting up the gas to be modeled: Redlich-Kwong (RK), Detailed AGA-8, Generic, BWR, NIST, and Misc. The RK method is ideal for natural gases being compressed at normal pressures and temperatures. AGA-8 is much more rigorous and is ideal for process gases or natural gases at non-normal temperatures and/or pressures. The Generic method may be cautiously used if a gas analysis is not readily available. For PLC programmers needing the accuracy of AGA-8 but desiring the simplicity of coding RK, you may linearly correlate the two methods via the Compare RK with AGA-8 option. Thus, you can get AGA-8 accuracy with RK-coding simplicity over the temperatures and pressures ranges for each stage’s suction and discharge. You can view simplified RK code by clicking on the indicated link on its tabs. This simplified code is ideal for embedding into PLCs. For convenience, various buttons are available to load, save, and clear gas analyses, as well as for normalizing components. You may define up to five (5) sets of gases. However, only




one may be used at a time. Future versions of eRCM will allow for using the other sets for defining sidestream compositions, etc. eRCM supports a special list of 398 gases under the Misc. option. This option also allows for dynamically changing the Gas-K value based on the suction temperature of the gas. Thus, it can provide a bit more accurate thermodynamic model for PLCs, when/if needed. Ultimately its method is similar to the Redlich-Kwong method. The AGA-8 Detailed Method has the added benefit that it not only indicates for what amounts of each gas its modeling is reliable, but it also indicates the maximum amount of uncertainty to expect when using it. More information about AGA-8 can be obtained from the sources listed on that tab. Furthermore, AGA-8 boards can be purchased and installed into PLCs to perform the intense calculations.

Note: AGA-8 Detailed Method should not be confused with the more common AGA-8 Gross Method. The Gross Method is usually used in flow meters as part of their routines for calculating flows. The Gross Method has strong restrictions on the pressure and temperatures of the gas being flowed and is not usually appropriate for the gas pressures and temperatures realized during the actual compression events.

The BWR (Benedict-Webb-Rubin) method is not currently implemented in eRCM. However, the code for this method is available by clicking on the Click Here for Sample Pseudo Code link. Thus, if your situation requires BWR modeling in the PLC, you can incorporate this code and use it to model gas compressibilities and Gas-K values. If implemented, this methodology will require more computing power of the PLC. The NIST (based on Peng-Robinson) method is not currently implemented in eRCM. However, if you have ACI’s NIST-based Gas Modeling software installed, you can elect to run the NIST calculations (via a separate program) to see if there are any thermodynamic issues with the gas being compressed at the pressures and temperatures expected. If not, model the unit via AGA or RK. If issues exist, then the compressor and/or coolers and/or sidestreams have not been sufficiently reviewed to prevent issues (such as formation of liquids). As such, consult with the OEM to resolve these concerns. This complex methodology is not suited for implementation into PLCs.




Cylinders Tab

Enter select information about each cylinder:

Compression Stage Enter a number, from 1 through 6, that indicates which stage of compression this cylinder is serving.

Enter a zero (0) to model omitting the cylinder. Frame Throw Number

For tandem cylinders, multiple cylinders will have the same throw number. Non-Lubed Factor

Typically 1.00 for lubed, and 0.95 for non-lubed. This option only affects capacity. Bore Diameter

Enter effective bore diameter of cylinder. Note: When modeling older units, consider if cylinder has been over-bored, or liners have been

added, as bore diameters stamped on nameplates may no longer be correct. Valves Per Corner [/Deactivated]

Number of Suction (or Discharge) valves per end actively engaged in the compression process.




If this end will be deactivated as part of the unloading scheme, then when it is deactivated, how many of the valves will be used (IE held open) is indicated after a slash (/). If the number of valves used during end deactivation is not specified (IE no /entry), then all valves on that end are assumed used.

Resistance Factor

Select Rf Assistance from the menu for more help on this topic. Active Rf’s are used to model valve losses during normal compression process. Deactivated Rf’s are used to model parasitic losses when the end is deactivated.

Valve Nose Diameter

Nominal diameter of the valve. The valve nose diameter is the measurement from outer edge to outer edge of the

smaller diameter (IE the part closest to the cylinder’s inner bore). Max Discharge Temperature

Typically range from 300° F to 350° F. Some users set to maximum temperature allowed by cylinder manufacturer Some users set to maximum temperature expected during normal operations.

MWP/RDP/MAWP/Other

For what pressure do you want to clip the curves to indicate unsafe operations? You need to consider relief valve settings and any piping limits. In general, for most applications this will be the cylinder’s MAWP.

VVP Increments

Set to zero (0) for smoothest movement. May be set to model VVPs moved in fixed increments. IE enter 0.25 for ¼ inch increments.

VVP Max Stroke

The OEM may have limited a generic VVP’s maximum open position to prevent undesired conditions. If so, this is usually done by installing a bumper/stop in the VVP.

VVP Min Stroke

The OEM may have limited a generic VVP’s minimum open position to prevent undesired conditions. If so, this is usually done by installing a bumper/stop in the VVP.




OEM Databases/User’s Database

Select from a list of OEM Cylinders or User Cylinders to quickly add that information into the model without having to type all of the information yourself. To add select cylinders to the short list (User’s List) find the cylinders of interest, and double-click on them. After double-clicking the cylinder, it should now appear in the short list. After all cylinders of interest have been added to the short list, close the main OEM Cylinders dialog box.




To enter the information from the cylinders on the short list into your model, you can:

Click on the cylinder of interest in the User’s List and drag that cylinder and drop it into the appropriate cylinder column, or

Right-click in the cylinder column of interest, and select Cylinder Quick List, and then from the displayed submenu, select which cylinder you want to use.




Stages/Throws Tab

Specific Gravity: Enter the Specific Gravity of the gas per stage. Gas K-Value: Enter the gas’s K-value. If you want to model dynamic gas K-values (IE values change based on temperatures and pressure ratios) then select the dynamic Gas-K option. Pressure Drops: Enter pressure drops from gages to flanges by fixed psi, percents or both. eRCM also has more elaborate methods for handling pressure drops. If you need more control over pressure drop calculations for a particular model, please contact ACI. Sidestreams: Enter the amount (MMscfd) of sidestreams in/out. The last stage cannot have sidestreams – as sidestreams after the last stage do not affect the model. Rod Load Limits: Enter the gas flange rod load limits in the first two rows. If you only want to model gas flange rod loads, then leave the remaining rows blank and make sure that the “Only model gas force rod loads…” item is checked. If you want to model internal gas pressure rod loads and/or inertia based rod loads, then enter those limits and also enter the appropriate weights per throw. Detailed instructions for where to find appropriate reciprocating weights per OEM are indicated in the various tabs towards the bottom of the screen. API618 now requires a maximum increment of 5° when checking Pin Reversal.




Load Steps Tab

There are two methods to creating a sequence of load steps: Standard Method and Alternate Method. Standard Method

First, enter the various volumes (in3) of pocket unloaders in the top table and then reference them in the table below, along with which (if any) ends should be deactivated for each load step. For example, in the top table enter 2034 and 2034 in rows A and C under cylinders HE #1 through #5, and then enter 2034 and 2034 in rows B and D under CE #1 through #5. These volumes define the possible added clearance volumes for each head end (HE) and each crank end (CE). Note: You do not need to distinguish between a front head end pocket and a valve cap pocket. In the bottom table, you describe each load step as to which pockets you want to open, and/or which ends you want to deactivate.

In general, Load Step #1 will be left blank to indicate that all pockets are closed and all ends are active – the general full load state of a compressor.

An input line such as “5A5B 4A4B” indicates that Cylinder #5 has a 2034 in3 HE pocket (A) and a 2034 in3 CE pocket (B) open, and that Cylinder #4 has a 2034 in3 HE pocket (A) and a 2034 in3 CE pocket (B) open.

To indicate a deactivated Head End on Cylinder #3, in the next column you would enter the text h3. For a crank end, you would enter the text c3. To deactivate the heads on Cylinder #1 and #2 and the crank end on Cylinder #3 simultaneously, you would enter h1 h2 c3.




Each load step line reflects all OPEN pockets and all DEACTIVATED ends for that load step. To copy the previous line’s text, simply press the Enter key on the blank line beneath it. To delete lines, press Shift-Delete. To insert new blank lines, press Shift-Insert.

Alternate Method

Select the Alternate Method tab, enter load step names, and then for each load step, enter the individual clearance percent settings per cylinder end. To indicate that an end is deacti-vated, enter a zero (0) for the clearance on that end.

Special Note: Text entered into the Alternate Method’s Load Step Name column will override the generic load step name entered in the Standard Method, even when the Alternate Method is not used. This allows the user to create custom names for each load step. To return to the generic names, simply leave the Alternate Method’s Load Step Name column blank.

For example, if you use the Standard Method, the load step name might be shown as “5A5B 4A4B” for load step #5. However, you may want the end user to view something different, such as “ Four 2034 in3 Pockets Open”. To do this, click on the Alternate Method tab, and enter the desired text for Load Step #5.




Analyze Model Tab

Pressing the F10 key, or clicking the large green Analyze Modeling Data button, will either:

Generate a list of errors (missing data, out of range data, etc.) regarding the current model. When this happens, you must correct the issues and try again before you can review performance results.

Generate a list of warnings (low and/or high values, inappropriate cylinders sizes, questionable number of

valves, etc.) regarding the current model. When this happens, you will want to review the warnings before moving onto the Graph/Analysis tab to review performance results.

Take you directly to the Graph/Analysis tab so that you can review the performance predictions

associated with the compressor model you have just created. Graph all points – even unsafe ones: Where curves would normally be clipped onscreen, eRCM will show dotted curves. While this option can help engineers view trends, dotted portions of curves always indicate potential areas of unsafe operations. Show only Full Load and Full Unload: Useful when you have many load step curves and you want to concentrate on maximum and minimum abilities of the unit. A quicker response time is associated with having to draw only two performance curves, instead of many curves.




Graph/Analysis Tab

Most analysis of compressor performance is available via this screen. You can:

Adjust desired operating point, Select desired load step, Review detailed performance information about current operating point, Discover reasons for why certain load steps cannot operate at certain conditions, Plots performance curves:

o Suction Pressure versus either Load or Flow, o Discharge Pressure versus either Load or Flow, o Suction Pressure versus Discharge Pressure for a single load step, o Suction Pressure versus Discharge Pressure for all/select load steps, o Suction Pressure versus Discharge Pressure for total unit flow abilities,

Compile list of points of particular interest.

Operating Point Dynamic Adjustments Load Step Selection Graph Area

Load Step Array Active Clearances Point Performance Operating Issues




Available Types of Performance

Suction Pressure versus Load Suction Pressure versus Flow

Discharge Pressure versus Load Discharge Pressure versus Flow

Suction Pressure versus Discharge Pressure for One Particular Load Step

Points of Interest

User can move the position of the current operating point by typing in new data in the Operating Point area, by adjusting the sliders in the Dynamic Adjustment area, or by dragging mouse in the Graph Area. To add a particular point to the Points Report, either click on the Add Point to Report button, or right-click the mouse and select Add Point to Report from the popup menu. To auto-determine best load step to use, change the Load Step Selection option from Manual to Best Load, Best Flow, or Best BHP/MM. Return to Manual when you want to change load step selection yourself.




Suction Pressure versus Discharge Pressure Graphs

After selecting the Ps vs PD tab, you will be prompted by a dialog box similar to the one shown above. To plot standard thumbnail (thumbprint) curves, select the first option Show Load Curves for Selected Load Step and then select Continue… (To display curves for a different load step, just select a new load step.)

To plot just a single thumbnail (thumbprint) curve at a fixed load, select the second option Show Load Curve for Desired Load =, enter desired load and then select Continue… (For all fixed load curves from all active load steps, uncheck the checkbox before selecting Continue…)

To plot a map detailing where particular flows can be achieved for all combinations of suction and discharge pressure, select the third option Flow Maps. Note: To redisplay the Ps vs Pd dialog box for selecting which type of pressure versus pressure plots you want to create, double-click anywhere in the current plot area.




Reports Tab

General: Review of your current entered data used to model the reciprocating compressor. Print for hardcopy record. Unloading: Review of your specified unloading sequence. Print for hardcopy record. Point(s): List of performance details from user-specified operating points.

Data in the Point Report is not saved. If you want these reports, then you will need to print them out before exiting the software.

You can save a list of key points of interest in eRCM. To do this, go to the Graph/Analysis tab, and then select the Points tab. All points entered here will be saved. You can elect to re-generate reports about these points by clicking the Generate Point Reports button.

Points Report can hold from 5 to 25 points, depending on all of the information detailed in those reports. If you “fill up” the Points Report, you can print out the current ones, clear report, and add new points to the report.

Tuning: Statistical results and/or general report of tuning the unit. Automation: Useful notes to consider when automating reciprocating compressors. For more information about automation, see the special How to Use Automation Option section. Unit Diagram: Diagram of the unit. You may design your diagram via any graphics package. However, save the image as a BMP or JPG file and then load it into the Unit Diagram report.

Be aware of the posted image size guidelines if you intend to create eRCM Viewer files for others. Note: For text reports, you can copy the text and paste into your own custom reports. To do this, go to the report of interest, right-click anywhere in the text, choice Select All from the popup menu, right-click in the text again and then select Copy.




How to Use Automation Option

If you want to embed compressor performance algorithms into a controller, then select the Automation tab from the Reports section. Next, click on the PLC Data (F12) button. A dialog box will appear with data that can be used with the provided single and two-stage algorithms for modeling your units. Please contact ACI for algorithms for modeling units with more than two-stages.

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To verify how accurate the generated PLC algorithms are to eRCM’s internal algorithms, select the Compare Predictions from PLC Code to eRCM button. Areas in yellow indicate where the two algorithms match well. Areas in blue indicate where the two algorithms differ by more than 2%. Areas in red indicate where eRCM predicts unsafe operations while the simplified PLC algorithm fails to determine unsafe conditions — the PLC programmer will need to handle these situations, if they arise, with additional constraint code.

Pseudo Code For users needing to model compressor performance in PLCs, eRCM provides sample pseudo code for single and two-stage compressor modeling. The PLC programmer will need to convert this code over to the language they use in their select controllers (IE Allen-Bradley, Siemens, GE Fanuc, etc.).




Tuning Tab

This feature allows the user to tune the unit’s load and/or flow predictions to better match measured data. Care must be taken when using this option. Tuning Methodologies:

No Tuning (allows for just gross adjustment of load and/or flow) Tune Against Pressure Ratio (ideal for fixed speed unit) Tune Against Speed (ideal for units with fairly constant suction and discharge pressures) Tune Against Pressure Ratio and Speed (Ideal)

Regionalization Method:

Global (user’s measured data equally applied to entire operating map) Local (user’s measured data applied only to areas around where data was measured) (Ideal)

Load Step Lumping:

Tune All Load Steps Identically (ideal for units with just clearance pockets) Tune Each Load Step Individually (only use if pulsation effects vary widely between load steps) Tune Load Steps by Family (ideal for units with pockets and end deactivators) (Ideal)

o A family is a set of curves based on activating just clearance pockets. Each time a new end is deactivated, a new family is created. When plotting graphs, eRCM renders different families in different colors.




Before tuning the unit, review Notes on Common Tuning Issues and Two Stage Guidelines.

Also, to make sure you have collected and entered data that represents your entire operating ranges, select the Tuned Areas button to display a plot of the various combinations of speed and ratio for which valid data has been entered. You may view plots by individual stages and/or load steps, or you may view all stages and/or load steps overlaid.

Tuning of the unit is the last thing to do. Make sure that other hardware-related items are accurate before proceeding with tuning.




Miscellaneous Items Variable Volume Pockets: For units that have manual and/or automated VVPs, you can model opening and closing them via the V.V.P.s tab. As you adjust the position of each of the VVPs, the point and/or graph performance will dynamically change.

Current Point’s Detailed Analysis Unit Tab: This tab displays the current load and flow based on the current operating point and the current load step. If there are any issues with using the selected load step at the current operating point, then errors and/or warnings will be displayed in the Problem(s) Predicted box. The Max Allowed Load value may change as the user adjusts speed, ambient temperature, or user-specified torque settings. Stages Tab: Shows various information about each stage.

Ps @ Gage and Pd @ Gage reflect the pressures that operators should see on the unit gages.

Ps @ Flange and Pd @ Flange reflect the pressures that the analyst should see based on average toe pressures.




Throws Tab: Shows various information about each throw.

Nomenclature: C=Compression, T=Tension, Flange=Forces based on static pressures at flange (IE external gas force rod loads), Internal=Forces based on dynamic internal gas pressures, Inertia=Forces based on dynamic internal gas pressures and dynamic inertia forces (a.k.a. net rod loads), Deg Rev=Degrees of Reversal for Compression/Tension.

To toggle between actual forces and percents of maximum allowed forces, double-click the “Throw Results” tab.

To view dynamic rod load plots, double-click on the row for the throw of interest.

You can adjust speed and weights from this screen. This can be useful to see if possible incorrect information about the current weights could have an undesirable effect on rod loads. You can toggle between viewing Rod Load forces and Pin Reversal forces by selecting the appropriate option. You can selectively view plots of forces for any throw by clicking on the Left/Right arrows adjacent to the Graph for Throw# text. To read a particular value, move mouse over plot and click.




Cylinders Tab: Shows various information about each end of each cylinder.

Item Description Item Description Ps Suction Pressure FixClr Cylinder’s Fixed Clearance Pd Discharge Pressure EffClr Effective Clearance Currently in Use Ts Suction Temperature IsenEff Isentropic Efficiency

Est. Td Estimated Cylinder Temperature BHP-A Adiabatic Horsepower Zs Suction Compressibility Factor BHP-VL Valve-loss Horsepower Zd Discharge Compressibility Factor BHP-PL Parasitic-loss Horsepower

VEs Suction Volumetric Efficiency Load Total load generated by cylinder VEd Discharge Volumetric Efficiency Flow Total flow produced by cylinder

To view the Pressure-Volume diagrams of the cylinders, double-click the row for the cylinder of interest.

You can adjust various items from this screen via the available sliders. This can be useful to see if possible incorrect information about the valves and/or clearance could have an undesirable effect on P-V cards. To selectively view any cylinder’s P-V diagrams, click the left/right arrows adjacent to the Cylinder # text. To read a particular value, move mouse over plot and click.




Special Notes Moving Files:

If you want to copy/move an eRCM model, then make sure you move/copy all files in the selected folder with the same name as the base “rcm” file. In general, this includes “rvf” for eRCM Viewer files, “bmp” for unit diagrams, “jpg” for unit diagrams, “mdb” for eRCM tuning databases, “rtd” for eRCM tuning files, and “dat” for eRCM special notes files.

Viewing Current Torque:

When in the Graph/Results section, move the mouse over the Adjusted Load (located in the Unit Results tab) value to review the associated torque.

Cut/Copy/Paste:

In general, each table has its own clipboard for cut/copy/paste actions. Thus, text from one table cannot be accidentally pasted into another table.

Shortcuts:

When in Manual Load Step selection mode, double-click a load step in the graph box to auto-select it. Press F10 to quickly redisplay Graph/Results window after making changes to your model. Press F5 to add the current point to the Points Report.

Calculators:

eRCM calculators are accessed via the main menu: Options – Calculators.

Frame Derate Calculator Clearance Calculator

Liner Addition Calculator Revenue Calculator




Notes on Tandem Cylinder: When applying cylinder numbers to tandems, each cylinder-

section of the tandem has its own number. o 2-Cylinder tandems have two (2) cylinder ID numbers. o 3-Cylinder tandems have three (3) cylinder ID numbers. o 4-Cylinder tandems have four (4) cylinder ID numbers. o 5-Cylinder tandems have five (5) cylinder ID numbers.

The cylinders are numbered first with the cylinder closest to the frame end (lower number) and subsequently numbered one (+1) higher for each cylinder section working towards the outer end, such as 1,2, or 5,6, or 1,2,3,4. But not, 3,6 or 8,7.

Read tandem notes carefully so that you are modeling your tandem cylinders the way that they are actually performing.




eRCM Menu Structure File Menu

New: Clear any current data entered, and start a new model. Open: Open a pre-existing eRCM modeling file (*.rcm). Save: Save current eRCM model. If no current filename is specified, then this will perform exactly like Save As. Save As: Save current eRCM model to a user-specified location with a user-specified filename. Import File: May be used to import an ACI Kernel File (special file used to exchange data between programs). Create Viewer File: Create an eRCM Viewer file based on the current modeling data. These files may then be loaded into other ACI software applications.

For most creations, the top item should be checked. For most creations, the remaining items should be unchecked. Certain features, such as those used for creating an RMX-compatible

model, may not be available to all users.




Export ACI Kernel File: Export an ACI Kernel File. Send…: Send the current eRCM file, eRCM Viewer file, or eRCM Database file, or eRCM Unit Image file to others via default e-mail software as attachments. Run…: Display a dialog box with shortcuts to software most often used when using eRCM.

Print Current Graph: Display a print preview window from which you may print the current graph. Print Current Report: Print the currently selected report. Copy Current Report to Clipboard: Copy current report information into the Windows clipboard. Blank Data Entry Form: Open a template for collecting data needed to model a reciprocating compressor. Template is in PDF format. You can print this form for you own data collection, or e-mail it to others. Exit: Exit the eRCM software. 1: Filename and Pathway: Lists your last loaded file – used to quickly reload the last accessed file.




Edit Menu

Cut: Copies the currently highlighted text into the Windows clipboard, and then deletes that text from the screen. Copy: Copies the currently highlighted text into the Windows clipboard. Paste: Pastes the textual contents from the Windows clipboard into the currently selected data entry field. Undo: When applicable, undoes that last cut and/or typing. In general, the following keystrokes work well in almost all Windows-based applications:

Control-Z Undo

Control-X Cut

Control-C Copy

Control-V Paste

F1 Key Help

Alt-PrintScreen Capture Current Window to Clipboard as a picture

Tab Key Move forward from one object to the next object

Shift-Tab Key Move backward from one object to the next object

Control-Tab Move from one TAB view to the next TAB view

Esc(ape) Cancel current selection




Options Menu

Graph Options: Option for selecting the resolution of the graphs for on-screen drawing. Typically not used. Default is Normal Resolution. May be set to Low Resolution for slower PC. This does not affect the accuracy of the software, nor does it affect the quality of the curves when they print to a printer. Driver HP Constraints/Options: Displays a dialog box allowing for a maximum driver loading, and for limiting the driver’s load based on speed and/or on ambient temperatures. Thus, if the driver does not derate in load by a linear relationship to speed, then you can input sufficient values to force it to derate via speed according to the driver’s OEM curves. In addition, if emissions are a concern, you can elect to derate/uprate the allowed load on the driver based on ambient temperatures. Both of the driver deratings can be employed simultaneously. Calculators: Displays a list of available calculators:

Clearance – Convert from percent clearance to actual volume, and vice versa. Liner Addition – Estimate changes in fixed clearance when adding a liner to a cylinder. Units Converter – Convert between Imperial and Metric units. Frame Derating – Derate compressor’s allowed load and frame friction to a different rated speed. Revenue Calculator – Only useful when in graph mode, allows determination of revenue based on

different operating points (IE different flow rates). Curve Fitter: Feature not currently available. Synch VVP Sliders: When checkmarked, dragging any one of the VVP sliders will result in all of them being dragged.




Select Errors Used to Clip Curves: Displays a list of restrictions used to clip performance curves. Toggle items to meet your needs, and then select Continue…

Display Curves with Limited Clipping Engaged: Used in conjunction with Select Errors Used to Clip Curves to affect the display of performance curves. If any of the base error checking is turned off, then a warning message will appear in the graph portion of eRCM: Define Beta Polynomial Coefficients: When modeling units originally modeled by Beta, this option allows you to input the associated coefficients of the modeling equations.




Rf Assistance Menu

Rf Worksheet: Displays a dialog for determining the resistance factors (Rf’s) for each end of each cylinder, in both its active and deactivated modes. Active Mode: Valve is being used in normal compression mode. Deactivated Mode: The valve is being manipulated so that the cylinder end is no longer effectively compressing gas. For example, fingers are engaged to always hold the valve in open mode, or a plug has been opened. For Head End bypass systems, even though the valves have not really been modified, use the values given by ACI to emulate any parasitic losses associated with the Head End bypass system.

To use this feature, first select the most appropriate tab. Then, either select the valve ID corresponding to the valves you have installed, or enter the relevant valve information supplied via the OEM to model that type of valve. For unknown/customized or legacy valves, select the General tab and enter the valve nose diameters to obtain a general Rf value for that type of valve. For more information about converting OEM data files to eRCM, download and review the specific document for each OEM from the ACI website: http://www.aciservicesinc.com/ercm For most accurate results, use the Known Valve Loss HP option in conjunction with analyzer data to determine an average Rf value for each cylinder end.




Help Menu

Update eRCM...: If you are online when this item is selected, the eRCM download area will be checked to see if a newer version is available. If so, the latest version will be downloaded and you will be given the option to install it. If you have problems, you can always direct your browser to www.ACIServicesInc.com/ercm where updates to the software may be downloaded to your PC, and installed. Contents: Shows the main eRCM Help File. eRCM Manual: Shows the PDF form of this document. Version Notes: Displays a dialog of corrections, changes, and additions to previous versions of the eRCM software. About...: Shows the eRCM Splash Screen, and the current version of the software.




Printing Graphs

To print any of the curves, simply select Print Current Graph from the main menu bar. Upon doing this, a preview of the page will be shown on the screen. To print this to a printer, select Print Graph Color (or Print Graph B&W) from the Print Preview menu bar. Graph Options: If you need to add/change certain items about the current graph, select Options-Settings from the menu. You can change the default titles, font sizes, Y-axis scaling, and more.




Print Preview Menus File

Export Raw Graphing Data: Used to export data to a file readable by other graphing software and spreadsheet applications. This option gives you the ability to import the graph data into a different program for even more graph manipulation.

Setup Printing Multiple Curves: Use when you want to print multiple curves without having to generate each one individually prior to printing. Here, you can specify a range of pressures or speeds and eRCM will print a series of graphs.

Print Graph Color: Prints the current graph to the select print as a color document.

Print Graph B&W: Prints the current graph to the select print as a black and white document. Print Load Step Information: Prints a document detailing the definitions for each load step. Close: Closes Print Preview and returns to the main eRCM software.

Options

Settings: Displays options that allow you to customize the graph. Copy Image to Clipboard: Places an image of the graph into the Windows clipboard. You may then

paste it into other applications. Preview Size

Full Screen (100%): Enlarges the Print Preview window. Others: Adjusts the Print Preview window accordingly.




Software License ACI SERVICES, INC. SOFTWARE LICENSE AGREEMENT LICENSOR: ACI Services, Inc., a member of the BSI Group Notice to User: It is important that you read this document before either opening the sealed package and/or downloading the same from the Internet or other depository, as well as prior to using the obtained demo ACI Services software (the "Software"). By using the Software, you agree to be bound by the terms of this Agreement. If you do not agree, return the Software to ACI Services, Inc. and you will receive a full refund of any license fee you paid. This is a legal document between you ("User") and ACI Services, Inc. The Software is distributed by ACI Services, Inc. and is protected by U.S. intellectual property laws and international treaties. SOFTWARE LICENSE. License Grant. ACI Services, Inc. grants User a non-exclusive, non-transferable, limited license to use the Software with compatible equipment. User is free to use the Software for purposes of demonstration; however, only one purchased data file may be used per operating copy and/or per product; that is when a data file is obtained for a specific compressor and/or a specific site, use is limited to a single data file configured for a single specific compressor or site, each bearing its own identification and/or serial number. Copying. The Software is licensed under a license that permits User to make reasonable archival or backup copies of the Software. Each copy made by User shall include the copyright/proprietary rights notice(s) embedded in and affixed to the Software. All other copying is prohibited. Other Restrictions. User may not loan, distribute, time-share, lease, rent, sublicense or transfer the Software or copies thereof, nor reverse assemble, de-compile or otherwise attempt to discern the source code of the Software, without prior written consent. Unauthorized use is prohibited. User will not knowingly export or re-export the technology and/or software supplied by ACI Services, Inc. or its licensors to any country or entity or for any use prohibited by the U.S. Export Administration Regulations or any other U.S. law, unless properly authorized by the United States Government. Title. Title to the Software is not transferred to User. Ownership of the enclosed copy of the Software and of copies made by User is vested in ACI Services, Inc. or its respective licensors, subject to the rights granted to User in this Agreement. LIMITED WARRANTY. ACI Services, Inc. warrants that the medium upon which the Software is provided by ACI Services, Inc. to User shall be free from defects in material and workmanship under normal use for a period of 90 days from the date of User's receipt thereof. DISCLAIMER. EXCEPT AS EXPRESSLY STATED HEREIN, THE SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, WARRANTIES OF PERFORMANCE OR MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. USER BEARS ALL RISK RELATING TO QUALITY AND PERFORMANCE OF THE SOFTWARE. The performance of the Software varies with various manufacturers' equipment with which it is used. ACI Services, Inc. does not warrant the level of performance of the Software or that of earlier versions superseded by new versions (whether or not distributed to User) will continue to be capable of access to and/or use with all equipment. ACI Services, Inc. does not warrant that the Software or the functions contained in the Software will meet User's requirements, operate without interruption, or be error free.




LIMITATION OF LIABILITY. User's exclusive remedy for breach by ACI Services, Inc. of its limited warranty or for any other claim shall be replacement of any defective medium upon its return to ACI Services, Inc. within the warranty period or, if ACI Services, Inc. is unable to provide a replacement which is free of defect, refund of any license fee paid by User with respect to such medium. In no event will ACI Services, Inc. be liable for any lost profits or other damages, including direct, indirect, incidental, special, consequential or any other type of damages, arising out of this Agreement or the use of the Software licensed hereunder, even if ACI Services, Inc. has been advised of the possibility of such damages. GENERAL PROVISIONS. Term and Termination. User may terminate this Agreement by ceasing all use of the Software and destroying all copies thereof. ACI Services, Inc. may terminate this Agreement if User commits a material breach hereof. This Agreement shall also terminate immediately upon User's receipt of a new version of the Software. Upon any termination of this Agreement, User shall cease all use of the Software, destroy all copies thereof then in its possession and take such other actions as ACI Services, Inc. may reasonably request to ensure that no copies of the Software remain in its possession. Effect of Agreement. This Agreement embodies the entire understanding between the parties with respect to, and supersede any prior understanding or agreement, oral or written, relating to, the Software. Governing Law. This Agreement shall be governed by and construed under the laws of the State of Ohio. General Provisions. Neither this Agreement nor any part or portion hereof shall be assigned, sublicensed or otherwise transferred by User. Should any provision of this Agreement be held to be void, invalid, unenforceable or illegal by a court, the validity and enforceability of the other provisions of this Agreement shall not constitute or be construed as a waiver of such provision or of the right to enforce such provision. U.S. GOVERNMENT RESTRICTED RIGHTS. The Software and accompanying materials are provided with RESTRICTED RIGHTS. Use, duplication or disclosure by the government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in Technical Data and Computer Software clause at DFARS 252.227-7013 or the Commercial Computer Software Restricted Rights clause at FAR 52.227-19 subdivision (c)(1) and (2), as applicable. Licensor is ACI Services, Inc., a member of the BSI Group.




Addendum: eRCM™ Data Input Notes

O.E.M. ID: Select this to display the OEM frames and cylinders by default. Also when selected, certain OEM modeling equations are used. When in doubt, select the ACI option. Base Pressure and Base Temperature are used to adjust flows to standard conditions. These are normally 14.65 psi and 60 °F. Many OEMs allow minimum suction volumetric efficiency of 15%. Lower to 15% to extend curve coverage.

When available, select OEM frame from displayed list to have eRCM auto-fill this required information. Frame Friction may be zero (0) for OEMs that include frame friction in their mechanical efficiency adjustments. Length of Connecting rod is only required if you will be modeling internal gas forces, inertia forces, and/or pin reversals. If the driver speed is less than the frame’s rated speed, you will need to derate the compressor.

Enter desired ranges of operation. If you expand ranges too much further than initial ranges from legacy OEM equipment, then you will want to start calculating inertia rod loads. The minimum Torque value is also used to limit the graphs. Sometimes you may want to lower this to get better curve displays.




Typically, use Redlich-Kwong for most natural gas applications. If the pressures exceed 1700 psig, or very cold gas, then consider using the AGA-8 method. If you do not have a gas analysis, use the Generic Method, but remember to enter a gas analysis before you generate your final model.

Cautions:

Comparing Methods:

For the PLC programmer, the AGA-8 method may be correlated with the Redlich-Kwong method to give AGA-8 accuracy with the more simplified RK routine.




Bore: Make sure that the cylinder has not been over-bored, or that a liner has not been installed. Either will change the effective bore diameter. Fixed Clearances: Changes to valves, addition of unloaders, and/or changes or addition of liners can all affect the original OEM clearances. If using an analyzer, run unit with the cylinder’s pockets closed – and with nozzle traces. R-f values: Use the R-f Worksheet to determine these numbers. Once known, they do not change with pressure or speed or load step. If new valves are installed, then the R-f values will need to be re-evaluated. R-f values are used in the prediction of valve losses and parasitic losses. Compare eRCM predictions of adiabatic loads and valve loss loads to analyzer runs (with nozzle traces!). Adjust R-f values to better match the analyzer’s measured valve losses – be careful about IHP versus BHP.

Retrieve Specific Gravity and/or Gas K from the gas analysis data, or from the OEM reports. Pressure drops from gage to flange can be found by reading gages while tapping the nozzles, from EDI reports, or packager reports. eRCM currently only handles sidestreams of the same gas type. This will change later.

For a more thermodynamically accurate model, you may elect to model dynamic Gas K values.

In eRCM, Gas Rod Loads are based on static gas pressures at the cylinder flanges, while Net Rod Loads are based on internal gas forces and inertia weights. eRCM will also display just internal gas force rod loads (used by some OEMs).




Each cylinder may have up to 26 unloaders on it. While that is unrealistic, it provides a lot of flexibility while investigating what-if scenarios.

Describe the sequence in which the unloaders are activated. The nomenclature of “4G” means that cylinder #4’s “G” pocket is opened.

To deactivate an end, describe which end and which cylinder is deactivated, such as “c3” which means Crank End #3.

To enter a user-determined load step name per load step, browse to the Alternate Method tab, and type in your own descriptions per load step.




Tuning Model to Real-world Data:

Enter pressures, temperature and speeds from the sensor readings, and not the pressures from the analyzer. Enter the analyzer’s predicted loads (BHP, not IHP) and flows.

Documents

Using eRCM Software - ACI Services, Inc. eRCM Software.pdfUsing either ACI’s eRCM software package (or Ajax’s eAjax software package) an engineer can create eRCM Viewer files