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Stage 4 of 15 / Calculation

Close the plant mass balance

Close stoichiometric water, hydrogen and oxygen flows from the delivered hydrogen rate.

  • Advanced
  • 15 stages
  • 12 min
  • Process and energy systems
In development Green Hydrogen Plant
Draft development workbench (noindex). These stages are exercisable on a direct development route for learning and review. The journey remains a draft: not published, excluded from search/sitemap by existing protections, and not independently engineering-approved. Quantitative outputs are screening/educational where implemented and must not be treated as certified design, OEM guarantees, project approval, or bankable results.
Professional review required.Engines and workbench are implemented for draft development use. Defaults, sources, heating-value basis and engineering assumptions still require independent review. The journey must not be published or sitemap-indexed from this phase. Current verification state: Needs engineering review.

After this stage you can

Learning objectives
  • State water, hydrogen and oxygen rates on a consistent hourly and annual basis.
  • Show that the reaction closes within 1e-6 kg/h.
  • Separate stoichiometric water from plant water withdrawal.

The engineering

The only chemistry used is 2 H₂O → 2 H₂ + O₂. Moles of hydrogen follow from the delivered mass and the CIAAW/IUPAC molar mass. Water and oxygen follow from stoichiometry. Closure error must be numerically zero at screening precision.

Theoretical water is about 8.94 kg per kg of hydrogen. Process water, treatment reject, cooling water and sanitation are additional and belong to later stages. Do not treat the stoichiometric figure as a plant water withdrawal.

Oxygen is a co-product. This balance accounts for its mass. Purity, pressure, offtake and venting are interface decisions, not credits.

EngiMetric / green hydrogen educational workbench

Green Hydrogen Plant — Educational Screening Workbench

Loading the hydrogen project state...

Draft development workbench (noindex). Inputs are saved in this browser only. Calculations shown are screening/educational outputs from the existing model where implemented; missing or unsupported quantitative areas remain explicit. Completing stages records self-declared learning progress only — it is not quantitative engineering capability, not an OEM guarantee, and not industrial/project approval.

Stage

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Inputs

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Edit the screening inputs for this stage, then calculate. Values you enter are marked as user-entered in the local project state; defaults remain illustrative until replaced.

Screening results

Educational model output

Results come from the existing hydrogen screening model. Unsupported quantitative areas, missing evidence, and review requirements remain explicit; outputs are not certified design or approval decisions.

Process & balance context

Textual screening views

This educational workbench presents stage-specific calculated outputs and limitations. Detailed interactive diagrams are not required for journey completion; use the stage results and assumptions panels to review boundaries, flows, energy, storage, and economics context.

Assumptions, limitations & review

From journey definition

Your deliverable for this stage

Capstone evidence

A closed reaction mass balance with explicit ratios per kg H₂.

Stage assumptions, limits and sources

Provenance

Assumptions

  • Pure liquid water is the reactant and is fully converted at the stack for mass accounting.
  • No hydrogen or oxygen is consumed by purification in this balance.

Constraints

  • Mass in equals mass out for the reaction envelope.

Limitations

  • No dissolved-gas losses, venting or purification consumption.
  • Oxygen condition (wet/dry, pressure, purity) is not modelled.

Review status

  • Needs engineering review
  • Professional review is required before publication or use as a design basis.

Stage progress is stored in this browser only. The explanation and every limit on this page remain readable with JavaScript disabled; the calculators need it to run.

Stage kind: Calculation / Journey: green-hydrogen / Stage: mass-balance