PTQ Q2 2024 Issue

can assist plant operators in evaluating the critical balance between maintenance cost and reliability to improve long- term performance. Some loss mitigation programmes are not focused spe- cifically on increasing plant reliability. These include capi - tal-intensive projects aimed at recovering flare gas, taking advantage of improved separation technologies (for exam- ple, tower internals), and purifying recycle/fuel gas (and thereby minimising olefin loss). Frequent objectives such as improving plant yields or expanding capacity can involve everything from unit opera- tional debottlenecking to incremental marginal yield shifts. Economic feasibility is a major factor in executing any pro- gramme in these areas. Recent technological advances in furnace coil design and metallurgy are having a significant positive impact on once-through yields, with the bonus of considerably extended run lengths. For furnace-limited plants, a 50% average run length increase could translate into an increase of 1-2% in annual furnace availability. Another option is adding furnace capacity, but this can be considerably more cost-intensive, at least initially. Though attractive in principle, incorporating flexibil - ity into a plant’s operation to take advantage of changes in demand or price disparities for ethylene, propylene, or another co-product may or may not be a practical pur- suit. One must consider not only market demand but also supply-side factors. For plants equipped to handle multiple feed types, shifting to heavier feedstocks to increase pro - pylene production is an intuitive response. Other options for increasing propylene production include the incorporation of metathesis units (at the expense of ethylene production) and propane dehydrogenation (PDH). The current focus on sustainability has also brought attention to methanol-to- olefins (MTO) technology, especially when integrated with blue hydrogen production from steam methane reforming and with processes for carbon capture, utilisation, and stor - age (CCUS). The overriding takeaway is that there are numerous options available for any particular producer to consider when attempting to address deficiencies in olefins demand vs supply. However, regardless of the technology consid - ered or the strategies employed, an intense focus on avail - ability must be maintained to keep the unit running and running well. Solomon Advisors can assist plant operators in achieving best-in-class performance. A Ujjal Mukherjee, Chief Technology Officer, Lummus Technology When there is an abundance of cheap gas such as ethane, producing ethylene from ethane is the most cost-effective production pathway. However, the product slate is severely tilted towards ethylene. Excess ethylene can be combined with 2-butene to produce propylene using metathesis, a low-cost energy-neutral process. Lummus’ olefins conver - sion technology is the most widely used route to convert ethylene to propylene to balance product slates in the most economic manner. When both ethane and propane are in abundance, we see a growing need for propane or propane/ butane dehydrogenation technology to produce a very high

yield of propylene. This approach has been adopted in the US, the Middle East, and even in China with imported pro - pane from the US. The other way to reduce ethylene and propylene produc - tion gaps is using mixed feed crackers designed to handle a wide range of feedstocks from ethane, liquefied petro - leum gas (LPG), naphtha, gasoils, and conditioned crudes and condensates. Mixed feed steam crackers have specially designed furnaces that can handle a wide range of liquids while maintaining long heater run lengths. Mixed feed crackers are particularly useful in the crude-to-chemicals strategy being adopted in many regions of the world. A Hernando Salgado, Technical Service Manager, BASF Refining Catalysts One strategy to adapt to changing market conditions, such as seasonal changes in ethylene and propylene demand, is having flexible process technologies that can adapt their product slate to the changing demand of both products. One of these process technologies is the always resilient work-horse of the refining industry (and becoming increas - ingly important to the petrochemical industry) – the fluid catalytic cracking (FCC) process. The FCC process is char - acterised by its inherent flexibility to manipulate severity, and therefore, it can have the flexibility to shift between types of light olefins produced. This is particularly true for FCC units specially designed to maximise light olefins – these can operate at very high severity (with reactor outlet temperatures higher than 540°C/1,000°F) and are equipped with special hardware, such as an additional riser to crack naphtha recycles or other light streams, and/or special riser terminations to maximise these secondary cracking reactions. Also, some units are designed to crack naphtha streams exclusively instead of conventional vacuum gasoil (VGO) or resid stock. These specialised FCC designs combined with the appro - priate FCC catalyst and additive systems are very effective in maximising a variety of light olefins products. The presence of this kind of process unit in a refining or petrochemical complex can provide huge flexibility to play between propylene and ethylene production by changing operating conditions, particularly severity. In addition, the selection of a proper catalyst, such as BASF MPS, MPS-R, Fourte, Fourtune or Fourtitude, in combination with an olefins additive to crack naphtha range material, such as ZIP, will contribute to enhanced flexibility in the FCC unit, allowing adjustment to shifting demand for propylene and ethylene. A Francy Barrios, Technology Engineer, Axens, Francy. Barrios@axens.net Ethylene and propylene are fundamental in the petrochemi- cal industry and have a wide range of applications across numerous industries, such as packaging, automotive, con - struction, and textiles. The market for these chemicals is growing due to the global demand for plastics and expand- ing end-use industries. For this, it is important to solve the huge gaps between ethylene and propylene production in certain markets.

PTQ Q2 2024