In this case-study the effects of the recycles in an ethylbenzene producing system are investigated, simulated and analysed. The studied steady-state technology contains of two recycle streams, hence serves as a good model system for our study. Recirculation is often used in chemical technologies, especially in separating techniques. Being a positive feedback, it is expected that the application of recycle streams may result in controllability problems. In this study composition control is dealt with, exclusively. Based on our simulation calculations, it is shown that applying recirculation in the studied technology can effectively lead to instability if no appropriate process control system is installed. A method is shown that enables the selection of the appropriate process control structure, which ensures constant product purity. The example systems behaviour is studied with and without recirculation in both steady-state and dynamic domains. All the reasonable composition control structures are simulated and compared. Based on the steady-state results, controllability indices are calculated for the distillation columns and the best control structures are predicted. The steady-state investigations are confirmed later by dynamic simulations, and finally the best composition control scheme is selected for the entire system -based on the controllability indices.

The control structure design is an important part of process synthesis tasks. The design becomes more difficult if recycle is present in the process to be controlled. The objective of this work is to clear up if the control structure design should be completed for the whole process simultaneously or it can be decomposed into subproblems involving only one unit of the whole system. Investigations show that the recycle can have an effect on the control structure that complicates the design problem. Simple case studies and exhaustive investigation of the industrial control problem are completed. Our investigations prove that decomposability can be applied simplifying the proper pairing of the controlled and manipulated variables, and this can facilitate the control structure design problem.

Throughout history, financial innovation was always interlinked with shifts in the word’s economic centre of gravity and the emergence of new power hubs. Nowadays, the huge interest in central bank digital currencies proves that we must have arrived at a new turning point in the development of money. Most studies, however, focus on financial issues related to CBDCs, and only few embark on discussing historical analogies and geopolitical consequences in a comprehensive way. Our study aims to deliver such an analysis. According to the results, the revolutionary effects of CBDCs might arise from re-modelling cross-border payments, i.e., achieving direct (atomic) transactions through multilateral platforms. The remarkable results of China in developing the digital yuan, and most importantly, acquiring a key role in international projects, reinforce the geopolitical trends of the last decade. Global or regional standard-setting will be a critical question, and in this regard, there is still some room for manoeuvre on the side of the U.S. which started its own CBDC development (Project Hamilton) belatedly. In the long run, it might be realistic to expect a scenario in which the global financial system is divided in two parts, a Western and an Eastern one.

A pénzügyi innovációk a történelem során mindig összefüggtek a világgazdaság súlypontjának mozgásával és a hatalmi centrumok kialakulásával. A digitális jegybankpénzek (DJBP) iránti óriási érdeklődés jól jelzi, hogy a pénz fejlődésének újabb mérföldkövét érhettük el. Míg azonban a DJBP pénzügyi kérdéseivel sok szakirodalmi mű foglalkozik, kevesebb a pénztörténeti párhuzamokat és a geopolitikai hatásokat átfogóan értékelő munka. A tanulmány e vonatkozásokat állítja fókuszba. Eredményei szerint a DJBP a határon átnyúló fizetések forradalmasításával – a közvetlen tranzakciókra épülő multilaterális DJBP-platformok által – hozhat fordulatot a pénzügyi és a világhatalmi rendszerben. Kína előrehaladott digitálisjüan-projektje és még inkább a nemzetközi projektekben való szerepvállalása napjaink geopolitikai folyamatait – a keleti pólus felemelkedését – erősíthetik. A kulcskérdés a sztenderdekre való befolyás, ebben Pekingnek óriási lépéselőnye van, bár ilyen szempontból az USA Hamilton Projektje sem késett még el teljesen. Hosszú távon reális forgatókönyv, hogy a DJBP-k korában a nemzetközi pénzügyi rendszer két nagy részre (nyugati, keleti) tagozódik.

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