PTQ Q3 2023 Issue

post-reforming due to lower feed conversion based on the temperature approach between the heating fluid at the bottom and the post-reformer tube exit temperature • No concerns over minimum per cent make-up fuel or curtailed steam balance • Higher reliability and cost-effec - tiveness in terms of avoiding the major risk of metal-dusting and the high cost of protection against it as a catastrophic corrosion character - ised by pitting and surface erosion in high-temperature alloys applied in the post-reformer. It is mainly caused by Boudouard carbon equilibrium in

ZF reactor-based SMR retrofit case analyses

Parameter

SMR de-stressing

SMR upgrading

Maximum current capacity (nameplate 100), %

100 115

Post-ZF retrofit capacity, %

100

S/C Ratio (molal)

3.1

2.8

Outlet temperature, ºC

860 -10

878*

Approach to equilibrium (end-of-run), ºC

-10 5.4 2.8 84

CH₄ slip, vol%, dry

5.5 2.8 75

Catalyst pressure drop (design 2.8 bar), bar

Average heat flux, kW/m Bridge-wall temperature, ºC

1,003

1,014 912**

Max. tube skin temperature (design 940 C), ºC

912

* Within existing outlet system design temp based on minimised temp non-uniformity and related margin ** Based on enhanced heat transfer and flattened radial temp gradient

Table 2

• Improved energy efficiency by improved heat transfer efficiency and the potential to operate at a lower S/C ratio • Enhanced SMR reliability by the possibility to operate at lower tube skin temperatures for a given capacity com - pared to pellets, by avoiding catalyst crushing and by the flexibility of the ZF reactor structure ensuring close contact with the wall during its lifetime. Table 2 provides an overview of the SMR performance for the following ZF retrofits case analyses:  De-stressing of existing SMRs which cannot achieve design capacity constrained by excessive pressure drop, leading to flow limitation and overheating of tubes due to pellet breakage causing throughput limitation together with increased maldistribution, poor heat transfer and/or lower catalyst effectiveness, just by replacing the pellets with ZF reactors  Capacity upgrading of 15% based on utilising the ZF reactor merits of higher heat transfer without pressure drop penalty even with increased throughput and also exploit - ing the reduced non-uniformity or temperature spread. This was achieved without exceeding the maximum tube skin temperatures while maintaining the conversion of the increased feed flow in terms of methane slip. Further, ZF’s high level of reforming capacity increase provides the following additional benefits against the best alternative technology (BAT) of integrating a post-reformer based on recuperative reforming with the existing SMR for obtaining such a step capacity increase: • Involves replacing only the pellets catalyst with ZF cata - lytic reactors and some minor case-specific modifications executable during a typical plant turnaround, compared to the capital intensity and major revamp with post-reforming and related extended project schedule and downtime • No energy efficiency penalty as in the case of

the temperature range of 500-750°C, through which the reformed gas must pass based on heat recuperation for post-reforming duty. This is not the case with the conven - tional process gas boiler, which involves low alloy materials and quick cooling of reformed gas to below the range. Table 3 provides the result of detailed techno-eco - nomic analysis (TEA) for an 80 mmscfd hydrogen plant by employing ZF reactors in place of state-of-the-art pellets for a 15% capacity upgrade retrofit and its net present value (NPV) over the typical 15-year period. The analysis is based on Honeywell UOP-developed simulation mod - els, the UniSim simulation model, the standard PDD tool, and optimisation. Key variables include stream composi - tion, utility price set, price of H2 of $1685/ton, natural gas feed price of $327/ton, fuel price (HHV) of 6.5/MMBTU) and HP steam export credit of $28/ton, cost of capital 12%, 350 days per year on-stream, and 2022 US Gulf Coast basis. Deploying ZF reactors in a new hydrogen plant SMR offers the unconstrained potential for design optimisation in terms of S/C ratio, outlet temperature, and average heat flux for SMR size reduction and better process efficiency, resulting in Capex and Opex gains, as well as enhanced reliability compared to conventional pellets. The NPV for the deployment of ZF reactor technology in new SMRs will depend considerably upon the plant flowsheet and its design optimisation based on various project-specific factors. End-to-end SMR optimisation and revamp solutions In short, the results and findings from our recently con - ducted pilot plant test programme conducted in our world- class pilot plant have validated our target merits in terms of achieving increased reforming capacity of at least 15% without any increase in methane slip, maximum tube skin temperature or pressure drop compared to the pel - lets under the same operating conditions. The pilot plant test programme final report was released by ZFRT-UCL in February 2023, delivering the results and conclusions based on detailed simulation and reconciliation of the col - lected data from all the test campaigns, which was fully ratified by Honeywell UOP, as presented in this article.

Result of detailed techno-economic analysis

15% capacity upgrade retrofit (ZF reactor vs BAT)

15-yr NPV

$28 million

Table 3

PTQ Q3 2023