narTC 2025
Topsoe low-carbon SynCOR Ammonia process
Henrik Rasmussen and Johan Malan Topsoe Inc.
the front end (reforming, shift, and CO₂ removal sections) but also in the back end (ammonia synthesis section), resulting in reduced Capex. The design of the inert-free ammo- nia synthesis loop provides another huge advantage. Where other large-scale designs require multiple pressure lev- els and multiple reactors in the ammo- nia synthesis section, SynCOR Ammonia uses a single S-300 ammonia converter in a standard, well-proven Topsoe ammo- nia synthesis loop with a single pressure level. The required ammonia converter size is already well-referenced industrially, with ammonia converters having a catalyst vol- ume above 150 m³. For comparison, an inert-free 6,000 MTPD ammonia synthesis loop in a SynCOR Ammonia plant will require less than 150 m³ of catalyst volume. In summary, the most important factors enabling the significant benefits from econ- omies of scale of SynCOR Ammonia are: • Attractive scaling factor for single trains. • Operation at 0.6 S/C ratio. • 80% reduced steam throughput. • Inert-free ammonia synthesis loop. • Reduced piping and equipment sizes. • Reduced energy consumption. • Single ammonia converter at a single pressure. • Opex savings of around 3%. • Able to capture more than 99% of the CO₂ as precombustion CO₂. The decrease in production cost result- ing from economies of scale is illustrated in Figure 3 for a conventional SMR-based plant and SynCOR Ammonia. The SynCOR reactor design consists of a Topsoe proprietary burner, a combustion chamber, target tiles, a fixed catalyst bed, a catalyst bed support, a refractory lining, and a reactor pressure shell, as illustrated in Figure 4 . SynCOR Ammonia is designed with two high-temperature shift reactors in series, a nitrogen wash to remove the carbon monoxide (CO), and the recycling of shift byproducts. The process layout has numerous benefits, such as close to zero byproduct formation and elimi-
Topsoe pioneered advanced autothermal reforming (ATR) during the 1990s and successfully commercialised plants oper- ating at a low steam-to-carbon (S/C) ATR technology in 2002, known as Topsoe’s SynCOR™ technology. SynCOR removes the limitations that other technologies have in reaching the optimal syngas composition. This advanced technology provides plant own- ers with a huge leap towards economies of scale in combination with a signifi- cant reduction in operational expenditure (Opex). It ensures high reliability and an on-stream performance of 99.5%, with lower requirements for operators and reduced maintenance. Topsoe has licensed four large-scale gas-to-liquids (GTL) sites globally, sev- eral of which comprise two production units per plant. Each unit produces syngas equivalent to more than 6,000 metric tons per day (MTPD) of ammonia at a low S/C ratio of 0.6. These plants have been in suc- cessful operation for more than 150 accu- mulative operating years. Topsoe’s large-scale SynCOR Ammonia™ plant has a capacity of 6,000 MTPD and is based on industrially proven equipment sizes and catalysts in both the frontend and backend ammonia loop in a single train configuration. The technology reduces the energy consumption gap for ammonia pro- duction by 10%, approaching the mini- mum theoretical levels. With the large production capacity comes a reduced capital expenditure (Capex) per ton of ammonia produced. This technology scales more efficiently than steam methane reforming (SMR)-based plants, having a lower scaling exponent. From a Capex perspective, both plant types can be considered for lower capaci- ties. However, SynCOR Ammonia becomes increasingly competitive compared to conventional SMR plants as production
Figure 1 SynCOR unit with an equivalent capacity of more than 6,000 MTPD of ammonia
capacity increases, and it clearly becomes the preferred choice at large capacities. Where oxygen is available over the fence, the technology is preferred even at very low capacities. Detailed studies have shown the fol- lowing additional advantages of SynCOR Ammonia plants: More than 3% lower Opex. Up to 50% make-up water savings, which is especially important in areas where water is a scarce resource. An average availability above 99% of the SynCOR reforming unit. More than 99% carbon dioxide (CO₂) capture, which is up to 50% higher than an SMR-based plant. The SynCOR Ammonia unit has a sig- nificantly reduced physical footprint due
to the elimination of the tubular reforming unit (SMR) and the use of a single-stage ATR for the entire steam reforming con- version. Figure 1 shows how small the SynCOR reactor is, even though its capac- ity corresponds to 6,000 MTPD of ammo- nia. Figure 2 shows the larger footprint of a tubular SMR and a secondary reformer with a capacity of 1,500 MTPD. In com- parison, the plot sizes of the SynCOR unit and the secondary reformer are very simi- lar and correspond to less than 5% of the plot size of the SMR. The most significant operating differ- ence between a conventional SMR-based plant and a SynCOR Ammonia plant is their S/C ratios. Conventional SMR-based plants operate at an S/C ratio of around 3, while SynCOR Ammonia plants operate at an S/C ratio of around 0.6. Consequently, steam throughput is decreased by 80%, resulting in much lower water consumption. SynCOR Ammonia plants also bene- fit from an inert-free ammonia synthesis, with the required nitrogen admitted just upstream of the ammonia synthesis sec- tion. In contrast, conventional ammonia plants introduce nitrogen in the secondary reforming reactor. These features enable significantly reduced pipe and equipment sizes for the SynCOR Ammonia plants, not only in
Oxygen
Natural gas and steam
CTS burner
Pressure shell
Refractory
HTZR™ target tiles Catalyst Catalyst support
Combustion chamber
Conventional plant
SynCOR Ammonia™
Capacity
Syngas
Figure 2 SMR-based reforming section with secondary reformer, 1,500 MTPD ammonia plant
Figure 3 Comparison of ammonia produc- tion cost using SynCOR Ammonia
Figure 4 Topsoe’s SynCOR
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