Raw ACM syngas is upgraded to PEM-fuel-cell-compatible purity through a multi-stage industry-standard cleanup train. Target purity: >99.99% H2 with <5 ppm CO — well below PEM catalyst poisoning threshold. The cleanup approach uses well-characterized industrial unit operations arranged in a Carbotura-specific sequence for the ACM syngas chemistry.
Engineering Detail
The cleanup train is a multi-stage sequence — stage names only (no vendor / chemistry detail):
- Hot cyclones — particulate and solids carryover removed from raw vapor.
- CRSRU (plasma reforming stage) — 1,300–1,800 °C plasma with no catalyst. Reforms CH4, tars and light hydrocarbons to H2/CO, AND simultaneously drives sulfur, chlorine and nitrogen contaminants to water-soluble species (HCl, NH3, dissolved sulfides). Pristine carbon recovered via dedicated cyclone downstream of the quench boiler.
- HRSG + condenser — heat recovered to steam loop; gas cooled from ~200 → ~40 °C. Water condenses out carrying dissolved contaminants (HCl, NH3, sulfides) with it.
- Oil–water separation — bulk contaminant path: organics + moisture partition; the aqueous phase (with dissolved acids, ammonia, sulfides) routes to Water MAX where NH4Cl / (NH4)2S / metals precipitate out as salt cake (see Section 4 Q12). Organics route to Aromatics MAX.
- Water-gas shift (WGS) — CO + H2O → CO2 + H2 over Fe/Cr at ~250 °C (~75% CO conversion in the modeled case). Gas stream at this point is already low in sulfur / chloride because CRSRU + OWS did the bulk removal upstream.
- PSA cascade — zeolite 5A + self-produced activated carbon (from Carbon MAX). H2 enriched to 4–5 nines (99.99%–99.999%).
- Trace polish + OEM acceptance — self-produced activated-carbon guard beds catch residual trace S / Cl / siloxane / alkali / Hg (small quantities remaining after upstream water-path removal); online analytical monitoring; ISO 14687 verification before PEM entry.
Key architectural insight: the CRSRU (1,300–1,800 °C plasma) does the heavy chemistry — at those temperatures sulfur, chlorine and nitrogen species convert to water-soluble ionic forms (H2S → dissolved sulfide; Cl → HCl aq; N → NH3 aq). These partition to the aqueous phase in OWS and leave via the water path, where Water MAX crystallizes them as salt cake product (NH4Cl / (NH4)2S; ~50.7 kg/h dry basis at 100 TPD). Downstream gas-phase steps (guard beds, PSA sorbent) handle trace polish only — a small fraction of what a conventional pyrolysis-cleanup train would need to remove. All guard-bed and PSA sorbent is self-produced on-site by Carbon MAX (module MAX-CRB-003).
PEM fuel cell platinum-group-metal (PGM) catalysts are highly sensitive to trace contaminants — sulfur, chlorine, siloxanes, heavy metals. Carbotura's cleanup train is designed with redundant guard-bed depth so that no single failure allows contaminant breakthrough to the PEM stack. Real-time analytical monitoring at multiple stage boundaries provides early-warning detection before catalyst damage occurs.
Engineering Detail
Multi-layer catalyst protection strategy:
- Redundant guard beds: dual-stage sulfur removal; dual-stage chlorine polish.
- Siloxane removal: dedicated adsorption stage upstream of PEM feed (siloxanes accumulate on PEM catalyst faster than sulfur; treated with dedicated capacity even where inlet siloxane concentrations are low).
- Heavy metals: trapped in upstream particulate + sulfur removal (Hg, As, Se predominantly bond to sulfur guard bed and are removed with it during regeneration cycles).
- Analytical layer: inline gas chromatography (GC) and mass spectrometry (MS) monitoring at 4 stage boundaries, with automated shutdown logic on any threshold breach.
- CAFI Digital Triplet: every module operates under a live-data multiphysics simulation monitoring 400+ variables in real time; deviation triggers pre-emptive maintenance before catalyst damage occurs.
Catalyst-life targets: PEM stack replacement cycle sized against a design assumption significantly longer than commercially guaranteed periods, with actual replacement driven by the analytical layer, not a fixed calendar.
Gas purification and compression consume a material fraction of the facility's gross generation — this is a fundamental characteristic of hydrogen upgrade technology. The facility remains net-positive on energy after this parasitic load; that is architectural (see Section 1, Q3).
Engineering Detail
Parasitic load breakdown by category (as % of gross generation):
- Gas purification (multi-stage cleanup): 4–7%
- Compression (syngas → PEM feed pressure): 6–9%
- Cooling loops: 2–4%
- Controls, sensors, analytical instrumentation: 1–2%
- Preconditioning (Pregenesis™ where applicable): 3–5%
- Total typical parasitic load: 16–27% of gross generation.
Range reflects feedstock chemistry, cleanup train complexity, and ambient conditions. Facilities designed for warmer ambients (the host jurisdiction's regions) trend toward the upper end of the cooling-loop range.