PTQ Q3 2022 Issue

•Master the processes they licence, hence are in the best position to design digital tools for these processes • Explain to users the possibilities and benefits associated with the digitalisation of their process units •Supply cost-effective, user-friendly digital applications, easy to implement in existing or new facilities •Provide valuable functionalities, including plant overview and unit-by-unit performance tracking, real-time economic evaluation, alerting functions, support to the planning department, operator skills management features, and so on • Use real-time data analysis to communicate with end-users •Offer tailored calculations, solutions, and optimisation options, including the ability to monitor the performance of closed-loop advanced process controls (APCs) and correct/ readjust such APCs as needed • Regard and handle digital monitoring as a requisite for the technologies they supply, as essential as online analysers, flowmeters, and thermocouples. Figure 1 shows an example of a modern aromatic complex configuration. A naphtha stream is hydrotreated and split into light naphtha (LN) and heavy naphtha (HN) streams, with the latter feeding a continuous catalytic reformer (CCR). Benzene and toluene are extracted from the light reformate, while the non-aromatics raffinate is typically directed to the refinery gasoline pool or used as steam cracking feed or fuel. The heavy reformate is sent to a xylene column where C 8 aromatics are collected overhead and feed a xylene loop for paraxylene separation, ethylbenzene conversion, and isomeri- sation of para-depleted xylenes. C 9 + aromatics are collected at the xylene column bottoms and further fractionated in a heavy aromatics column. C 9 and C 10 aromatics are recovered overhead of the heavy aromatics column and processed with toluene in a transalkylation unit to produce additional benzene and xylenes, while C 11 + aromatics are collected at the heavy aromatics column bottoms and typically exported as fuel oil. Aromatics complex: interconnected processes The aromatic complex constitutes a textbook case of inter- connected processes. Below are a few examples of process changes influencing other processes: • The naphtha splitter operation can be adjusted to retrieve more molecules from the LN stream and direct them via the

HN stream to the CCR for additional benzene production. The CCR operation needs to be fine-tuned accordingly, not only to maximise aromatic products but also to minimise concurrent olefins make; further, the reformate splitter, as well as the extraction process, need to be able to accom- modate such additional benzene product. • Paraxylene adsorption utilisation at near full capacity heav- ily depends on the proper operation of the upstream clay treater and/or selective hydrogenation unit. 3 Meeting olefins specification is critical for the C 8 aromatics stream feeding the paraxylene selective adsorption unit, and thus real-time management of potential upsets in the olefins removal pro - cess is essential in modern aromatic plants. • In facilities where xylenes isomerisation is split between gas phase and liquid phase processes, energy consumption is minimised when traffic through the liquid phase process is maximised. However, xylene loop ethylbenzene concentra - tion increases with traffic through the liquid phase process, which reduces the overall loop efficiency. Consequently, energy consumption reduction, ethylbenzene conversion, and overall loop efficiency require real-time optimisation. • The heavy aromatics column operation sets the nature and quantity of C 9 , C 10 and possibly C 11 aromatics that will feed the transalkylation process to produce additional xylenes and benzene. More heavy aromatics in the feed typically means higher xylenes production per pass and a higher ageing rate for the catalyst used in the transalkylation unit. Higher xylenes and lower benzene production or vice versa impact paraxylene recovery as well as benzene fractionation. • Feed selection affects all units in the aromatics plant. The use of a process operating simulator (POS) for pre-screen- ing of available naphtha streams allows overall complex simulation and prediction of product slate associated with different feed scenarios. The POS is an essential planning tool for fast decision making to respond to PX production demand as needed. Real-time digital performance monitoring cases Nowadays, data densification techniques such as machine learning enable the creation of soft sensors to compensate for lab analyses low frequency. Consequently, it is possible to determine – with the same granularity as based on actual

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Distillation Column Optimisation

Messenger

Alerts

Reconciled MB

Aromatic Yeild Maximisation

Columns Overview

Instantaneous Dashboard

Alerting

Reconciled Yields

Debutaniser

Optimised Unit Performance

Normalisation

Depentaniser

Optimiser Status

Normalised PKIs

SEND

General Performance

Unit Capacity Usage

Reactor WAIT

Material Balance

ExReactor Yield : H2

ExReactor Yield : C5+

ExReactor Yield : Arom...

ExReactor : Aromatics i...

Reformate RON

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Figure 2 CCR in operation

PTQ Q3 2022