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No. 62 June 2007 news from AspenTech - heat exchanger design excellence through research

In this issue.... What's New aspenONE 2006

Aspen Plate+ Immiscible liquids Aspen Properties & NIST Aspen FIHR Aspen MUSE Aspen Tasc+ Aspen Acol+ Aspen Teams & EN 13445

Acol+ Fan curve

Migration to HTFS+

Process benefit of enhanced heat exchangers

Customer Presentations at 2006 UGM

Training

Current Products

To Contact Us

What's new in aspenONE 2006 for heat exchanger products

Aspen Plate+™ our new thermal design program for plate heat exchangers. A key part of the 2006 release is Aspen Plate+™. The latest addition to our HTFS+ Design System which houses Tasc+, Acol+, Teams and now Plate+. Plate + is our new program for design rating and simulation of plate heat exchangers. Building on the best of our HTFS and B-JAC heritage, the product combines the flexible B-JAC user interface with the core modelling of HTFS from Aspen APLE™. Design optimisation has been improved over the approach in APLE and the program features enhanced output graphics. We have also improved access to the databank of manufacturer's plate geometry. Our comprehensive industry-standard physical property options with COMThermo®, Aspen Properties® and B-JAC property databases are all included.

Handling two liquid phases (such as condensation with immiscible liquid condensate) All of the products in the HTFS+ Design System share the same physical property features. The aspenONE 2006 release brings powerful capabilities for modelling streams with two separate liquid phases.

The presence of immiscible liquid phases has a major influence on heat transfer and pressure drop processes. Whilst it has always been possible to

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approximate how such systems behave with the HTFS or B-JAC programs, it required the user to adjust key properties manually. Now our "+" programs will automatically calculate appropriately-weighted properties from data for separate liquid phases. These data for phase properties can be generated by selecting the required vapour-liquid-liquid equilibrium method in Aspen Properties or in COMThermo. When "+" programs are integrated with our process simulators, Aspen Plus or Aspen HYSYS, this extra information is automatically shared with the thermal calculations.

It is also possible to input the properties of your liquid phases directly, should you require. The figure below from Acol+ shows the calculated properties for two liquid phases.

Now you can be confident that Tasc+, Acol+ or Plate+ are calculating the best possible estimates of local heat transfer coefficient and frictional pressure gradient for systems with immiscible liquid phases.

The following table identifies the recommended vapour-liquid-liquid methods to be used for immiscible fluids for both the oil & gas and chemical industries:

Aspen Properties combined with NIST AspenTech has formed an alliance with the US National Institute of Standards and Technology (NIST). In addition to the traditional thermophysical and thermochemical property data users may now access the NIST database from within Aspen Properties which is included in all the HTFS programs. This new database more than doubles the number of components in the product library by adding nearly 12,000 new compounds. Those wishing to access the NIST data may do so through the Aspen Properties Database Selector program by specifying the "Aspen Properties Enterprise Database." This innovation is a vast increase in our already powerful property capabilities and will be the subject of future articles in Hotline.

FIHR™ enhancements The aspenONE 2006 includes a new release of Aspen FIHR™.



Now customers may be able to directly specify roof tubes. This is a common arrangement in cabin heaters which in the past had to be approximated in FIHR modelling.

To assist FIHR users who are monitoring the operation of heaters in situations where they would like to avoid undesirable or hazardous operating conditions, we have arranged that a number of threshold conditions can be specified for key operating parameters. Checks include the following conditions:

Firebox tube temperature Firebox tube heat flux Firebox process fluid outlet temperature Convection section fluid outlet temperature Convection section gas velocity Convection section gas pressure drop

The program now also warns of potentially unstable two-phase flow regimes such as "slug flow" in firebox or convection section tubes.

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MUSE™ enhancements Capability to handle more complex plate-fin exchangers: You can now specify an exchanger with up to 20 process streams (previously 15), and up to 360 layers (previously 240).

More detailed modelling: The potential number of calculation steps along an exchanger has been doubled to 400.

New Fin Performance calculations: An improved set of correlations has been developed for fin performance, giving friction factor and Colburn J factor as a function of Reynolds number, for use when no such data are available for direct input into the program. The new correlations are based on a comprehensive survey of fin performance data, and take into account the type and proportions of each fin. Full details of the correlation, and Research Reports detailing results of the assessment exercise on which they are based are available via the HTFS Research Network. A new input switch is available, giving the option of reverting to the old correlations.



Schematic of Aspen HTFS+ compact exchanger rig

Entrainment in Plate-Fin Kettles: Plate-fin cores can be used to replace tube bundles in Kettle reboilers, with the flow being calculated to match the driving head of liquid. New correlations permit checking of plate-fin kettles for liquid entrainment and results are now reported in the output.

Output of Metal Temperatures: When layer by layer calculations are performed, there is an option to output the metal temperature at every calculation point in every parting sheet or end-plate, to the special INTOUT file. This detailed information will permit assessment of thermal stresses in operating exchangers.

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Aspen Tasc+™ A major portion of our development team's effort over the past 18 months has been spent on restructuring of the incremental calculations for v2006 of Aspen Tasc+. This project essentially was a complete re-write of our calculation engine. The new method uses most of the proven local heat transfer calculations for heat transfer and pressure drop previously utilized by Tasc+, but provides an improved solution procedure for calculating temperature and pressure profiles along the heat exchanger. The new method has been designed to provide a better representation of performance, addressing more exotic shell types with increased accuracy. Goemetric effects are much more accurately represented and this major advance will allow us to address the needs of customers designing units with varying baffle pitch and exchangers, with different numbers of tubes per pass. Another important facet of this development is the ability of the user to control solution accuracy and resolution of calculations giving added flexibility for users embedding Tasc+ models in process simulations of Aspen HYSYS® and Aspen Plus®.

The traditional or "standard" method is the default method used by Tasc+ 2006 but users may opt to deploy the new "advanced" method for simulation and rating of TEMA E shells. The Tasc+ development team has issued a number of Cumulative Patches since the original release of Tasc+ 2006. Within these, the advanced method capability has been expanded to include TEMA - F, G, H, and J shells.

The advanced calculation method is invoked from the Calculation Options section of the Input. The screen shot below shows selection of the advanced option and corresponding convergence options available with this new feature.



Selection of advanced method

Additional technical enhancements added to Tasc+:

Design optimization improvements - now conforms to TEMA-specified maximum unsupported spans Aspen Plus interface improvements Calculation engine consistent with Aspen Plus with double precision calculations Setting plan improvements - now shows expansion joints, vertical shells show vertical if required, vertical shell supports, and couplings

The following figure shows a vertical shell in that selected orientation.

Vertical shell setting plan

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Aspen Acol+™ - Design Enhancements Acol+ 2006 features a major enhancement to it's unique optimized design capability. Acol+ previously performed a systematic search by varying the main geometric design variables to arrive at an optimum design determined by the



capital cost of the air-cooler. The optimum design ensured that adequate surface area was available to meet the specified heat duty and pressure drops. The program now has the capability of basing the cost estimate on capital cost or the sum of capital and operating cost. Operators are increasingly concerned about the total cost of ownership of their assets. Our new Acol+ design option is an effective tool to help the thermal and process design specialist to rapidly screen their designs to meet this requirement.

Selection of Acol+ optimization criteria

To facilitate the expanded design optimization described, the user can now have the program perform the design by varying the outside mass flow rates within user-specified limits on flow rate and exit temperature. Acol+ will optimize on the smallest required surface area for each outlet temperature and then select the optimum exchanger on cost. This new design method brings a new higher level of efficiency to the user by automating a design procedure that previously had to be done manually by trial and error.

Acol+ optimization output

Physical Properties Common with the other HTFS+ products, Acol+ can now display the individual components mass fractions for both the liquid and vapor streams at each point along the condensation or vaporization temperature profile.



Acol+ phase composition tables

This allows users to evaluate the phase composition at exit if required.

Additional technical enhancements included:

Improved cost estimates - now based on Aspen Icarus logic Performance data specification can be isolated to specific passes - the user can specify start and end passes for new-style performance data in the same way as for other tubeside enhancement options Nozzle size selection based on maximum percentage pressure drop Calculations are performed in double precision to improve compatibility with AspenTech's steady state simulators. In addition to all these new features Acol+ continues to offer unique detailed simulation including modelling of air-cooled heat exchangers with selected fans switched off, natural convection operation modeling tubeside phase separation and much more.

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Advances in International Design Codes

The release of Aspen Teams 2006 incorporates the European construction and design standard, EN 13445. The creation of EN 13445 involved extracting the best features of existing international codes and as such, it is considered by many to be superior to any individual national code. This new standard provides the user with direct means of conforming to the essential safety requirements of the Pressure Equipment Directive 97/23/CE (PED). By using Teams/EN, the designer will have the advantage of presumption of conformity to the Essential Safety Requirements of the directive itself thereby achieving economic and technical advantages in new equipment design. Teams/EN will provide considerable savings in equipment capital costs when compared with Teams/ASME/PED. Material costs are frequently greater using the ASME code because of the thicker components required due to lower material allowable stresses (typical safety coefficient of 2.4 on the ultimate strength of the material versus 3.5 in the ASME code). However, in some cases, savings attributable to lower material costs with EN 13445 are partly offset by additional costs of non-destructive testing when compared with ASME requirements. On the other hand, Post Weld Heat Treatment (PWHT) costs are frequently greater for ASME since the PWHT requirements depend on the wall thicknesses.



The thermal integration with Tasc+ and Hetran will enable Teams/EN to determine automatically the state of vessel contents in terms of pressure, volume and the class of fluid. This integration will further enable Teams/EN to apply the EN 13445 design rules successfully based on the nature of the fluid. This considers degree of hazard and operating conditions.

In mid 2007, ASME will publish their new Section VIII Division 2 rewrite. The objective of the revised code is to modernize section VIII division 2 by including advanced material properties and design methods. Section 4, Design by Rule Requirements, provide design methodology for complete vessel designs thereby competing with the old Division 1 rules. It is believed that these new rules provide a more uniform margin of safety against failure than other Codes.

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Aspen Acol+ fan curve

The release of Acol+ in December 2005 included a new Fan (performance) Curve capability. This allows users to determine how a given geometry of air-cooled heat exchanger will perform with a prescibed fan. The following illustrates the new fan curve option functionality:

1. The fan curve data is defined in Acol+. It refers to a specified reference rotational speed. In the screen shot below we have input a value of 200rpm.

2. When we run Acol+ the program iterates to find the operating point on the fan curve and the consequent thermal perfomance 3. The thermal performance is ouptut in various forms. Below we show that it can be read from the API output. We can see that total air flow for the unit will be 61.3 kg/s and the thermal duty will be 1398 kW



4. If we increase the operating fan speed from 200rpm to 250rpm, what thermal duty can we expect? 5. This screen shows the input of the operating fan speed where we enter the new speed.

6. Running Acol+ again, the program Acol+ applies the fan laws to define a new fan curve at the higher speed. We converge on a new air flow and operating duty this time shown in the Performance summary output as 1503 kW with an air flow of 75.33 kg/s.

These two cases can be directly compared are shown below in the Acol+



Recap display.

7. The following figure illustrates graphically the operating points calculated by the program on the fan performance curves, as input at 200rpm and re-calculated at 250rpm.

Aspen Acol+™ gives you a new powerful capability for determining the effect of fan operation on the thermal performance of an air-cooled exchanger unit. In addition to the study outlined above, for an existing fan installation you can simulate the effect of air temperature, which affects air density and hence the mass flow of air through your unit. You can look at the effect of adjusting fan blade angle, increasing this can increase the air flow and hence the performance of your unit. If your performance is adequate you can reduce the blade angle and consume less power in your fan motors. This new capability can also be used to evaluate the benefit of alternative fans or study the value of fan speed control.

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Migrating to the new HTFS"+" products

Immediately following the merger of AspenTech and Hyprotech in the summer of 2002 our R&D team began planning for two major projects. After about 2½ years of intensive work, the first project was completed with the release of Aspen Tasc+™ and Aspen Acol+™ in December of 2005. These new products



provided our customers with our next generation platform for design and simulation of shell & tube and air-cooled heat exchangers. Further projects were to similarly update the remaining programs to form a complete HTFS+ Heat Exchanger Design & Rating suite. This will bring all our tools to a common user interface, now called the HTFS+ UI.

AspenTech's latest complete product release, aspenONE 2006 began to ship in December 2006. This release included our new thermal program for plate heat exchangers Aspen Plate+™. The HTFS+ UI now provides a single environment to support Aspen Tasc+, Acol+, Plate+ and Teams. FIHR and MUSE will be replaced by new products within the HTFS+ UI in subsequent releases of aspenONE.

What will happen to our 'Heritage' products? As we move closer to our goal of having the entire HTFS+ suite of programs running under one common user interface, we will start to sunset our heritage products. The affected products and relevant dates are shown in the table below:

AspenTech will continue to provide limited program updates to the sunset products that will include corrections for significant errors, for the remaining support period.

If you currently licence one of our 'Heritage' products you can migrate to the new applications for a modest one-time fee. To allow a smooth technical migration to the new products, customers can opt to retain the heritage products for a 12 month transition period. Companies with multi-year agreements do have the option of continuing with the heritage products until their agreement expires. We strongly encourage customers to migrate to the new HTFS "+" products as soon as is reasonably possible to take advantage of the superior platform for future development:

They contain the best features of our rich heritage Advanced physical property options Advance user interface with powerful links to other software (AspenTech & 3rd party Superior useability of input, output and reporting Powerful technical developments

We are very keen that all our customers benefit from the major investment AspenTech has made in combining the very best of it's B-JAC and HTFS heritage. We have an extensive program of development for all products in the HTFS+ suite which will bring capability which was not possible to offer in the architecture of the heritage products.



The figure above illustrates the status of our migration process in terms of companies licensing products. We have been delighted with the support for our new products as manifest from the over 300 companies who have opted to move to our "+" products in the 13 months since release. Feedback received from companies that have migrated have been very favorable.

If you want to ensure you migrate to the new HTFS+ products or have an questions on the migration policy, please contact us at [email protected]

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Evaluate the total process benefit of enhanced heat exchangers (Aspen Tasc+™ and Aspen HYSYS® with Koch Heat Transfer's Twisted Tube® Exchanger Modelling)

Increasingly process and refinery operators are looking to reduce costs, expand production and extend the run-time of their assets. Many emerging technologies offer enhancements over conventional shell and tube exchangers. From the operator's standpoint it is vital to be able to conduct a cost benefit analysis on such technologies in the context of the overall process. The integration of Tasc+ with Aspen HYSYS provides you with the means of evaluating the process impact of enhanced exchangers, exploring energy savings and the potential for increase in throughput.

The case study which follows explores replacement of conventional segmental-baffle shell and tube exchangers with Koch Heat Transfer Twisted Tube exchangers in part of a crude pre-heat train.

The Base Case Tasc+ modelling part of a crude pre-heat train with existing shell and tube heat exchangers. This comprised 4 identical exchangers in two parallel paths on the crude side. All 4 units were connected in series on the hot stream run-off side. The HYSYS flowsheet shown below shows the configuration of the crude distillation unit.



The simulation includes Tasc+ models of each of the exchangers comprising the hot end of the pre-heat train.

Koch Heat Transfer Twisted Tube Re-vamp Tasc+ was used by Koch Heat Transfer to produce an optimum arrangement of twisted tube exchanger to occupy the same shell. It is simple to export the original Tasc+ models from HYSYS including process data and all the stream physical properties. The unit was designed within the original pressure drop constraints of the existing segmental baffle shell and tube units. The optimum twisted tube exploited the ability of KHT twisted tube exchangers to configure a 2-pass shellside flow (shrouded F-type) within a normal E-type shell. The figure shows the selection of KHT Twisted Tube exchangers in Tasc+.

The Tasc+ setting plan below shows the original shell arrangement with the shrouded F-type plan overlayed.



The original tube layout and the TT tube layout are shown below. One benefit KHT claim for TT exchangers is the ability to replace square or rotated-square tube pitch arrangements with triangular pitch arrangements in a bundle that remains cleanable on the shell side. This contributes added surface area to the replacement bundles and is a significant factor in enhanced performance in appropriate applications.



Primary Benefit on a Single Unit Focusing on one exchanger in the train it can be seen below that the new TT revamp achieves a higher duty than the original single segmental baffle design. The table which follows used the Tasc+ "Recap of Designs" feature to compare key parameters, the table was cut & pasted to Excel.

Primary Benefit for the Process The above illustrates that a single unit will perform more duty but what can we expect from the process when we install the replacement TT bundles in all 4 units? Because the hot stream routes through all units there will be a strong interaction. Of course HYSYS can easily model such interaction, all we need do is import the new TT Tasc+ model into each of the HYSYS exchangers in our existing simulation. After converging the simulation we can immediately demonstrate that the heater thermal duty has reduced by 3.1MW. It is easy to calculate that the fuel saving would be worth over $600,000 per annum. KHT advise that the replacement bundles would cost under $400,000. Thus we can achieve a satisfactory project payback of 8 months.

Up-rating Throughput What if we elected to utilise this improved performance to process more crude? The integrated solution with the new Tasc+ Twisted Tube models within HYSYS rapidly shows we can process an additional 3000 bbl/day if we



reinstate the fired heater to the original firing rate. The HYSYS flowsheet below corresponds to this case with the higher crude throughput.

Calculations show that we do not need additional pumping capacity. This increased through-put, with current margins on crude refining, can increase operating profit by around $4,500,000 per year. A very compelling case for the proposed re-vamp especially if run-time between exchanger cleaning can be maintained.

Summary Koch Heat Transfer have experience of applying TT exchanger re-vamps to many exchanger services including:

Crude pre-heat Hydrotreater Feed / Effluent Rich / Lean Amine Sour Water Feed / Effluent Quench Water Coolers Overhead Condensers Kettle Reboilers

The figure below shows a typical KHT Twisted Tube unit in assembly with the shroud being installed.



Any Tasc+ user wishing to evaluate TT exchangers for their applications may request a license and the TT modelling software dll from: www.kochheattransfer.com. KHT will make such a license available to any operating companies or engineering companies subject to some technical training requirements. Once the dll is installed on a computer equipped with Tasc+, the KHT Twisted Tube input items become immediately available. This article demonstrates the real ability to evaluate the impact on your process of alternative designs of heat exchangers, including enhanced types like KHT Twisted Tube exchangers. It illustrates the combined power of Tasc+ and process simulators Aspen HYSYS® or Aspen Plus®.

Alan Guy, Area Sales Director, Thermal Design Specialist, Koch Heat Transfer. Tom Ralston & Julien Cazenave, Aspen HTFS+, AspenTech.

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Customer Presentations at Aspen HTFS+ Annual Meetings

Following the pattern of annual meetings in recent years, our gathering in Cologne in November 2006 brought forward three important customer presentations.

Quantifying and monitoring fouling of refinery heat exchangers: presented by Pierre Séré Peyrigain of Ineos, Lavera, France, outlined a system developed for monitoring fouling on exchangers in the pre-heat train of a vacuum distillation unit. This demonstrated the value of TASC exchanger models integrated within Aspen HYSYS and linked to a custom-made Excel application.

Second to none plants at BASF - the value contribution of thermal design: presented by Stefanie Lehnert-Batar, BASF, Ludwigshaven, Germany, looked at the wholistic approach to process design adopted within BASF for new plant and for re-vamps. This approach is demanded by the need of reducing the total cost of ownership of processes in a global economic environment. It requires use of the best tools in particular for large scale continuous processing where some 30% of the capital value is associated with heat exchange.

Validation of Aspen Tasc+ against TASC using ARKEMA exchanger databases: presented by Dominique Deur-Bert, ARKEMA, Lyon, France and Jim McNaught, TUV - NEL described the objectives and the content of the ARKEMA heat exchanger database. This is a system on exchanger modelling cases which the company use to verify versions of HTFS+ shell and tube mdellelling software prior to general deployment of a new version across ARKEMA's global operations. All of the exchangers in the database are practical operating units in plants belonging to the company. Any significant discrepancy in performance prediction is examined and differences resolved in consultation with Aspen HTFS+ staff. This presentation and the work behind it also provide validation which will give confidence to other users.



Reboiler cold stream circulation rate from ARKEMA presentation

All of the presentations are reproduced on the HTFS+ Research Network site for Research Network members: www.htfs.com/resnet/ann_meeting/default.asp

We thank our customers for presenting these works and in allowing us to reproduce them on our web site and in brief here.

The 2006 annual meetings in Cologne included full hands-on courses on Tasc+ and Boiling and Reboilers. Some 51 Customers attended from 34 companies.

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Training

Check out our training web site at: support.aspentech.com/supportpublictrain/TrainHome.htm

Full course descriptions can be viewed and you can register online.



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Current Products

Register at support.aspentech.com/supportpublicasp/RegisterBegin.asp to enable you to download the latest patches, receive relevant monthly e-Bulletins, search Knowledge Base for solutions and submit & track your own enquiries.

Aspen Tasc+ 2006TM

Design and performance simulation of all your shell and tube heat exchanger requirements, including thermosyphons.

Aspen TASC 2006TM / Aspen Hetran 2006TM

Design and performance simulation of all your shell and tube heat exchanger requirements, including thermosyphons (support will cease as of 30th June 2008).

Aspen Teams 2006®

Mechanical design of shell and tube heat exchangers.

Aspen Acol+ 2006TM

Software for design and performance simulation of air cooled heat exchangers and simulation of heat recovery units, air conditioning and refrigeration exchangers.

Aspen ACOL 2006TM / Aspen Aerotran 2006TM

Software for design and performance simulation of air cooled heat exchangers and simulation of heat recovery units, air conditioning and refrigeration exchangers (support will cease as of 30th June 2008).

Aspen Plate+ 2006TM

Design, rating and performance simulation of plate heat exchangers.

Aspen APLE 2006TM

A single package for design, rating and performance simulation of gasketed plate and frame heat exchangers (support will cease as of 30th June 2009).

Aspen MUSE 2006TM

Performance simulation layer by layer, crossflow calculation and 'first-shot' thermal design of multistream plate-fin heat exchangers.

Aspen FIHR 2006TM

Simulation of fired process heaters, including radiant and convection sections with multiple process streams.

Aspen FRAN 2006TM

Rating and performance simulation of power plant feedwater heaters.



Aspen PIPE 2006TM

Single phase and two phase flashing flow calculations in unbranched pipeline systems (support will cease as of 30th June 2008).

HTFS Research Network TM www.htfs.com/resnet.asp

The HTFS knowledge base developed over the past 35 years. This includes online access to the Handbook, research reports and a selection of design reports via the web. Customers can also have a close involvement in directing our research and the evolution of our products through participation on Review Panels.

Review Panel Chairmen Tubular Heat Exchangers Jim McNaught Furnaces & Fired Heaters Laurie Haseler

Compact Heat Exchangers Vishwas Wadekar

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To contact us

E-mail: [email protected] Web: www.htfs.com

Development centreReading, UK

Tel:+44 (0)118 9226405 Fax:+44 (0)118 9226401

Details of further office locations can be found at:

www.aspentech.com/corporate/locations.cfm

Technical Support Centres

e-mail: [email protected]

See the website for a complete list of phone & Toll-free numbers in your areasupport.aspentech.com/SupportPublic/centers.html

Europe and Africa (EMEA) + 44 (0)118 9226555 Middle East (EMEA)

+965 4610790

North America, Latin America (NALA) + 1 888 996 7100 (Toll-free from US, Canada, Mexico) + 1 617 949 0700 (from outside US, Canada, Mexico)

Asia and Pacific Region + 60 3 2719 5550 (Kuala Lumpur, Malaysia)

+ 81 3 3262 1743 (Tokyo, Japan) + 61 7 5448 1355 (Australia) + 86 10 845 38 613 (China) + 91 20 56230614 (India) +82 2 3779 5809 (Korea)



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Aspen Technology, Inc., Worldwide Headquarters, Ten Canal Park, Cambridge, MA 02141-2201, USA

Tel:+1 617 949 1000 Fax:+1 617 949 1030



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