PTQ Q3 2023 Issue

ZF reactor differentiators over state-of-the-art pellets

Characteristic

Pellets – status quo Ceramic – cement

Zoneflow – a breakthrough Engineered metallic foil Structured annular casing Aligned stack, fully uniform Robust, higher voidage, flexible None or minimised – entire life No attrition and setting stable dP Open-acess’ catalytic surface, minimised diffusion limitation Full peripheral contact – in cold AND hot condition, lower gradient Higher (by multi-fold times) ~ Half; same over entire life ~ Double; near-wall turbulence

Substrate Geometry

Pellets in various shapes Random, non-uniform

Loaded pattern

Strength and voidage

Mutually limiting

Flow/temp maldistribution Thermal cycling effects Geometric surface – active

Inherent – rising over time Attrition and setting; dP >> Inherent diffusion limitation,

sites access

partial utilisation

Catalyst – tube wall proximity and temperature gradient

Sporadic wall contact

irregular gaps; larger gradient

Catalyst effectiveness

Low (inherent)

Pressure drop Heat transfer

Base, increasing over life Base, stagnant inner film

Table 1

Based on industry best practices and modern methods for loading pellets, at best, the target can achieve as low as +/-3-4% variation in pressure drop over the multiple tubes in the SMR (measured using a preset air flow in each tube dur - ing loading), leading to inherent flow variation. In contrast, since ZF reactors are in a uniformly stacked identical metal- lic structure assembly in all the tubes, the non-uniformity of pressure drop and related flow rate per tube is deemed to be negligible (as confirmed by 3-D CFD modelling 4,5 ). The uniformity of feed flow per tube minimises the variations in heat pick-up across the multiple tubes (based on a homoge- neous stirred firebox). It thus minimises temperature spread and maldistribution in terms of tube skin temperatures as well as the outlet gas temperature from each tube, thereby requiring lower design margins for the outlet system. The results and findings of the pilot plant test programme alidated the uniformity and robustness of the metallic foil substrate and stacked module design assembly. It also thereby prevents settling, crushing, and breakage. These are typical problems with pellets, causing increasing pressure drop over their operating life and thus worsening the maldis- tribution of flow and related tube temperatures. The reactor’s design capabilities were demonstrated and verified in all the test campaigns based on the measured

methane slip being very close to that simulated from the operating conditions (and expected approach-to-methane equilibrium). If there were any feed bypassing along the tube wall due to gaps between the ZF assembly and tube wall under hot/operating conditions, the methane slip in the reformed gas (and the approach to methane equilibrium) would have been far higher than observed. Pilot plant description The ZFRT pilot plant has been built for extensive testing and performance evaluation of different steam reforming cata- lysts. It is a world-class unit in terms of capacity, reformer geometry, boundary conditions, instrumented provisions, and operational safety. The driving force and underlying objective to realise such an ambitious venture was to have an unconstrained and dedicated capability for testing and demonstrating the performance of ZF reactors compared to conventional state-of-the-art pellet catalysts under the same operating conditions covering (near-) commercial levels in terms of operating conditions, heat flux, and feed conversion. Referring to the diagram of the ZFRT pilot plant in Figure 2 , the main individual functioning units (IFUs) are desulphur - isation and compression of the supplied natural gas, feed

Natural gas

Feed NG desulphurisation

NG compression

NG ow control

Steam pressure & S/C control

Analysis

Vent

Gas cyclinder battery (N, Ar, H)

N, Ar, H ow control

Steam reformer (electric furnace)

Steam Super-heater

Demin water

Boiler feed water treatment / dosing

Electric boiler

Flare

Syngas cooling / steam generator

Water pumps

Water pre-heating

Syngas hot are

Analysis

Micro-lters

Pressure control

Figure 2 Pilot plant block flow diagram

PTQ Q3 2023