Most of the distillation columns reboiler steam flow is controlled in cascade from boil-up stream temperature that is not robust enough if the unit experiences feed stream composition, flow or temperature variations (affecting feed stream relative volatility) e.g. NGL unit DeC1/DeC2 cyclic feed flow fluctuation after upstream dryer beds change-over. Due to column trays hold-up volume the steam rate is not adjusted on time that intermittently leads to e.g. propane losses as well as ethane slippage after normal feed stream property is reinstated.

PE&T has resolved these issues successfully in existing plant by simulating the column operation and feed stream variations in dynamic mode selecting and testing available Trays temperature transmitter as a master controller. As a results PE&T proposed the Tray and temperature set point that need to be maintained with PID tunning parameters to minimize the impact of feed variation on the product quality.

If you experience distillation column product quality off-specification due to cyclic changes in the feed stream you can contact us at: info@peng-tech.com

As the compressor stops, the pressure on the discharge and suction settle-outs i.e. equalizes via anti-surge valve. In case of two or more stage compression, the interstage check valve are assumed passing and the mass of vapor on the HP stage discharge re-distributes across LP stage suction.

PE&T can develop the whole compressor loop pressure settle-out via dynamic simulation to confirm if final pressure is lower than the LP stage suction design pressure as well as the seal design pressure. In addition, using compressor rotor inertia data PE&T can confirm if reverse rotation of the shaft is possible in the above-mentioned scenario.

Please contact us at: info@peng-tech.com for additional information.

As facilities matures and operating conditions changes, regular re-validation HAZOP/PHAs sessions often identifies and advises to perform adequacy checks of the existing PRV for new conditions.

As per API521: “dynamic simulation can be used in pressure-relief system design to calculate transient pressure increases or to calculate required relief rates from individual pressure-relief devices. Conventional methods for calculating relief loads are generally conservative and can lead to overly sized relief and flare system designs. Dynamic simulation provides an alternative method to better define the relief load and improves the understanding of what happens during relief”.

PE&T has performed numerous PRV rating calculations for complex systems and scenarios such as:

• Fire case

• Distillation column reboiler/condenser failure etc.

• Vapor induced liquid displacement (2 phase relieve)

Please contact us at: info@peng-tech.com for additional information.

PE&T has performed numerous studies on effectively preparing units/equipments to release for intrusive maintenance activities. For example, PE&T has provided an option to purge contained 18% H2S in the slug-catcher via hot fuel gas using alternative routes that reduced the duration of the process by 10 hours and prevented excessive flaring experienced in previous years.

PE&T can provide solutions for effective Plant or Unit start-up and shutdown operations that can save time and prevent excessive flaring. Please contact us at: info@peng-tech.com for additional information.

With dynamic simulation PE&T can offer realistic available time for ESD systems to activate to prevent undesired consequences considering equipment design limits, mass and energy balance.

Please contact us at: info@peng-tech.com for additional information.