Retrofitting a low temperature shift reactor in a client’s SMR hydrogen plant marked a pragmatic approach to improving efficiency and contributing to ongoing decarbonisation efforts.
Partially funded by the New Zealand GIDI fund, the project’s purpose was to convert residual water and carbon monoxide from the upstream SMR and HTS reactors to produce hydrogen. The goal was to reduce total input fuel and process feed gas while achieving the same hydrogen output, contributing to sustainable efficiency.
For the design basis, a full simulation of the existing hydrogen plant was conducted using Symmetry. This simulation provided an in-depth understanding of the system conditions and operations required to effectively assess technical feasibility, evaluate financial return, and accurately forecast potential emissions reductions. Now online, the LTS is reducing hydrogen plant emissions from natural gas by about 3% for the same total hydrogen production, in addition to reducing loading on the downstream molecular sieve.
A critical part of the retrofit was the design of a nitrogen carrier gas heater, used for fresh catalyst reduction and for preconditioning the reactor prior to startup after plant turnaround. The unit condenses the available 18.5 bar wet steam, achieving a nitrogen ∆T of 190°C; this task was technically demanding, requiring a remarkably high exchanger effectiveness – the ratio of real to theoretical maximum heat transfer. The design was successfully performed using HTRI with process inputs determined from Symmetry.
Commissioning proceeded as designed, leading to the effective reduction of new catalyst in the reactor which is crucial for optimum performance. Now operating smoothly, the successful implementation of the LTS system underlines the viability of retrofitting established technologies to enhance hydrogen plant efficiency and provides a viable pathway for future sustainability initiatives.
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