Conference papers and presentations


Past papers

GPA Europe ( London, 21 Nov 2013)

Process modelling requirements for the safe design of blowdown systems – changes to industry guidelines and how this impacts current practice

Conventional methods for calculating relief loads are generally conservative and can lead to oversized relief and flare systems, resulting in unnecessary capital expenditure. In some cases they can be non-conservative, leading to potentially unsafe system designs.

Recently-developed high-fidelity dynamic simulation techniques provide a method to accurately define the relief load, analyse low temperatures, assess the real capacity of the system and analyse the potential for staggered blowdown, as well as to improve the understanding of what happens during relief.

Changing industry guidelines are likely to necessitate a change in the way O&G companies approach process safety, in particular the design and analysis of pressure relief and blowdown systems. This presentation shows how industry practice is beginning to evolve in anticipation of the forthcoming changes.

[Presenter: Apostolos Giovanoglou, Principal Consultant, PSE Oil & Gas]

AIChE Annual Meeting (San Francisco, CA, USA 03 - 08 Nov 2013)

1. Modelling the Manufacturing Process and Product Performance of Roller Compacted Pharmaceutical Tablets
Emmanuela Gavi1, Gavin K. Reynolds1, Mark A. Pinto2, Sean K. Bermingham2, (1)Research and Development – Pharmaceutical Development, AstraZeneca plc, Macclesfield, United Kingdom, (2)Process Systems Enterprise, London, United Kingdom

2. Modeling Drug Precipitation in the Human Gastrointestinal Tract Using gCOAS
Kaoutar Abbou Oucherif1, Jennifer Lu2, Sean K. Bermingham3, Dan Braido4, Filipe Calado3, Lynne Taylor5 and James D. Litster6, (1)School of Chemical Engineering, Purdue University, West Lafayette, IN, (2)School of Chemical Engineering, Purdue University, west lafayette, IN, (3)Process Systems Enterprise, London, United Kingdom, (4)Rutgers University, Piscataway, NJ, (5)Industrial & Physical Pharmacy, Purdue University, West lafayette, IN, (6)School of Chemical Engineering, Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN

3. A Novel Computational Oral Absorption Simulation Tool to Integrate API Crystal Properties and Drug Product Design Attributes to in Vitro and in Vivo Performance
Kazuko Sagawa1, Ravi M. Shanker2, Rong Li1, Kaoutar Abbou Oucherif3, Dan Braido4, Filipe Calado5 and Sean K. Bermingham5, (1)Pfizer Worldwide R & D, Groton, CT, (2)Pharmaceutical Sciences, Pfizer Worldwide R&D, Groton, CT, (3)Purdue University, West Lafayette, CT, (4)Process Systems Enterprise, Cedar Knolls, NJ, (5)Process Systems Enterprise, London, United Kingdom

4. Conversion of FBRM® CLD Data to Psd Data: Application to a Needle-Shaped Industrial Case, for the Estimation of Crystallization Kinetics
Niall Mitchell1, Bing-Shiou Yang2, Sean K. Bermingham1, Soojin Kim2 and Hassan Mumtaz1, (1)Process Systems Enterprise, London, United Kingdom, (2)Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT

5. Modelling the Effect of Process Variables On the Polymorphic Transformation of L-Glutamic Acid
Niall Mitchell, Sean K. Bermingham and Hassan Mumtaz, Process Systems Enterprise, London, United Kingdom

6. Modelling of Fluid Bed Drying At Different Production Scales in Pharmaceutical Drug Manufacture
Xiaorong He1, Mark Pinto2, (1)R&D Pharmaceutical Development, Boehringer Ingelheim, Ridgefield, CT, (2)Process Systems Enterprise, London W6 7HA, United Kingdom

7. Applying Crystallization Modeling to Improve the Understanding of a Batch Cooling Process of An Agrochemical Active Ingredient
Rhea Brent1, Manish Parmar1, Neil George1, Pauline Sillers2, Michael Bryce2, GIllian Clelland2, Hassan Mumtaz3 and Niall Mitchell3, (1)Syngenta, Bracknell, United Kingdom, (2)Syngenta, Grangemouth, United Kingdom, (3)Process Systems Enterprise, London, United Kingdom

8. An Integrated Model for the Thermodynamics of the Film Coating Operation the Mixing Phenomena in the Drum and the Distribution of Properties in the Coated Tablet
Salvador García-Muñoz1, Alejandro Cano2, Jianfeng Li2, Daniel O. Blackwood 3, Alfred Berchielli3, (1)Process Modeling and Engineering Technology, Pfizer Worldwide R&D, Groton, CT, (2)Process Systems Enterprise, Inc., Cedar Knolls, NJ, (3)Drug Product Design, Pfizer Worldwide Research and Development, Groton, CT

9. Whole-Chain CCS System Modelling: Enabling Technology to Help Accelerate Commercialisation and Manage Technology Risk
Mark Matzopoulos and Alfredo Ramos, Process Systems Enterprise, Inc., London, United Kingdom

10. Model-Based Economic Optimisation of CO2 Compressor Train Design and Operation
Alfredo Ramos, Process Systems Enterprise, Inc., London, United Kingdom

11. Optimization of Distillation Column and Separation System Design
Rodrigo Blanco, Process Systems Enterprise Ltd, London, United Kingdom

INCHEM 2013 (Tokyo, Japan, 30 - 01 Nov 2013)

Click here for the two japanese presentation abstracts.

Off-shore Plant Design Symposium Fall 2013 (Seoul, Korea, 17-18 Oct 2013)

1. Process modelling requirements for the safe design of blowdown systems – changes to industry guidelines and how this impacts current practice

James Marriott, Praveen Lawrence*, Apostolos Giovanoglou, Process Systems Enterprise Ltd

Safe design of pressure relief and blowdown systems requires that safety valves, relief orifices, flare piping and KO drums are all sufficiently sized, to ensure that the process is protected from over-pressurisation and that emergency depressurisation can be executed rapidly. An essential design step is to ensure that temperatures resulting from auto-refrigeration are sufficient to avoid the risk of brittle fracture in both the process equipment and flare system.

However conventional calculation methods rely on a number of assumptions and approximations. In particular, calculation of safe design temperatures and relieving rates for complex blowdown segments are typically based on analysis of a single pseudo-vessel with simplified representations of the fluids thermodynamics and heat transfer.

Best-practice in engineering and operating companies when assessing risks in pressure relief and blowdown systems now increasingly involves the application of high-fidelity dynamic simulation techniques. For example:

  • rigorous, distributed blowdown system models are used to assess the risks of cold temperature brittle fracture during process depressurisation
  • analytical methods are used when performing pool and jet fire evaluations.

Evolving industry guidelines are likely soon to necessitate a change in the way all Oil & Gas companies approach process safety, in particular the design and analysis of pressure relief and blowdown systems. This presentation discusses how industry practice is beginning to evolve in anticipation of the forthcoming changes.

2. High-fidelity combined dynamic modelling of depressurising vessels and flare networks: accurately assess flare system capacities to safely reduce CAPEX

James Marriott, Praveen Lawrence*, Apostolos Giovanoglou, Process Systems Enterprise Ltd

The use of dynamic modelling for relief system design can result in a considerable reduction in capital expenditure (CAPEX) while simultaneously improving plant safety. By making relatively simple dynamic analyses using data that is mostly already available in some form, it is often possible to refine network designs to arrive at systems with a significantly lower capital cost but demonstrably meeting safety requirements. Similarly, it is often possible to find additional capacity during retrofit, thus removing the need for additional capital expenditure.

Conventional flare header design techniques use instantaneous peak relief flows in steady-state simulation in order to assess system capacities and determine back-pressures downstream of blowdown valves (BDVs) and pressure safety valves (PSVs), Mach number in the headers and radiation at the flare tip. This steady-state assumption is highly conservative. While conservative approaches may be desirable in safety system design, they can nevertheless lead to gross overdesign throughout the system.

Rigorous dynamic analysis that combines upstream process with the flare network provides a much more realistic capacity analysis than steady-state or pseudo-dynamic techniques can provide. It does this by taking into account:

  • system packing, where the gas pressurises the available volume in the flare network, increasing the buffering capacity (this can take into account the potential for reverse flow into inactive branches of the network if necessary)
  • the effects of staggered blowdown, where flare events are sequenced in order to minimise peak flows
  • proper handling of low-pressure sources, where flow may be reduced as the system back-pressure rises
  • the time required for the pressurisation of the large flare network volume
  • the rapidly-decreasing feed rates from some of the oversized blowdown valves.

The net result is typically significantly-reduced observed peak flows, helping engineers to avoid oversizing of the flare header and the flare stack itself. Alternatively, for existing systems, additional capacity can be identified, making it possible to establish whether there is sufficient capacity to accommodate new sources and thus avoid the need for a new header and flare.

In addition, the more accurate low-temperature analysis provided by dynamic simulation, which takes the duration of low-temperature flows into account, typically enables a reduction in use of expensive alloys for low-temperature service. This contrasts with the use of a steady-state approach, which may result in very conservative (and hence expensive) requirements for use of alloys.

This presentation shows how the application of dynamic analysis of the combined process and flow network can now be based on a much more realistic representation of behaviour than previously possible. This provides an essential means to reduce overdesign or identify additional capacity in order to minimise capital expenditure while meeting or exceeding safety guidelines.

3. Ensuring vessel integrity during low temperature operation: rigorous model-based design techniques

James Marriott, Praveen Lawrence*, Apostolos Giovanoglou, Process Systems Enterprise Ltd

Maintaining vessel integrity during low-temperature operation is paramount for all Oil & Gas operations. However, mitigating against the effects of low temperature can be very expensive in terms of capital cost associated with low-temperature alloys, or the reduced production resulting from, for example, the need to depressurise a flowline slowly in order to avoid low-temperature situations. It is thus very important to quantify integrity risks very accurately, in order to ensure safe operation but not over-design vessels unnecessarily.

Particular consideration must be given to transient operations in oil&gas processing plants. For example, during plant blowdown, separators such as high-pressure (HP) knock-out drums must be able to withstand two-phase inlet flows at high flowrates and very cold temperatures for periods of up to 15 minutes.

Such flows can create areas of localised low temperature in the metal walls of the vessel, which may exceed safe limits for embrittlement temperature. Flows at different temperatures may enter through several nozzles, creating temperature differentials between adjacent areas on the vessel wall, leading to unacceptable thermal stresses. Both types of hazard can threaten the integrity of the vessel as a whole. However, the thermal inertia of the large metal mass is often considered to be sufficient to compensate for the effects of the inlet cold flows, preventing the most affected areas of the vessel from reaching unsafe temperatures.

In order to make decisions about safety that simultaneously ensure safe design and operation and also minimize capital costs, it is increasingly necessary to quantify the effects of such events very accurately.

This presentation shows examples of current approaches and their shortcomings, and describes a significantly more effective approach that combines hybrid Computational Fluid Dynamics (CFD) and dynamic vessel wall models to ensure both safe design and minimised capital expenditure.

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