Hydrogen chloride synthesis burner and absorption (33 wt-% hydrochloric acid, steam recovery)

Chlorine burnt in a 10 % excess of hydrogen in a steam-raising synthesis furnace, the HCl gas absorbed in a water-cooled graphite falling-film absorber to 33 wt-% hydrochloric acid and the tail gas scrubbed with the absorption water; chlorine and hydrogen from chlor-alkali-1. Concept stage, 26.4 kt/a HCl, assumed basis.

Calculation maturity: not assessedDesign maturity: Concept (research)Not independently reviewedChlor alkaliReport a problem with this process
Research outputNot engineering advice and not an approved design: do not use it for construction, operation or safety decisions. What this means

Dry chlorine and wet hydrogen from the adjacent membrane-cell chlor-alkali plant (chlor-alkali-1) burn in the synthesis furnace; the hydrogen excess consumes all chlorine and the oxygen the chlorine carries. The furnace raises steam at 1000 kPa(a) from the reaction heat and sends the HCl gas at about 250 degC to an isothermal falling-film absorber, where it dissolves in weak acid from the tail gas scrubber to 33 wt-% acid. All absorption water passes the scrubber first; the excess hydrogen leaves through the vent.

All values are concept estimates. The furnace outlet and duty are calculated by cheme (complete conversion at the equilibrium limit); the absorber and scrubber are specified values from an independent balance script, and the acid's enthalpy rests on an assumed heat of solution because no ChemE-as-Code property method covers HCl-water yet. See DESIGN.md of the engineering files for every assumption and gated step.

Capacity
10 t/h hydrochloric acid 33 wt-% = 26.4 kt/a HCl (100 %) (ASSUMED)
Operation
8,000 h/a
Location
generic (not chosen), adjacent to a chlor-alkali plant
Engineering gates
Concept and feasibility (no results yet)
Maintainers
Artur Schweidtmann
Design basis and assumptions (4)
  • D-001 boundary: chlorine and hydrogen gas at the fence to 33 wt-% acid in storage, steam export and vent; no anhydrous HCl, no acid storage or loading, no utility generation
  • D-005 R-101 converts all Cl2 and O2 (equilibrium limit at 523 K); no kinetics
  • D-006 the balance is a specified-split model (scripts/balance.py); the acid enthalpy rests on an ASSUMED heat of solution
  • Construction, transport and end of life are outside the preliminary LCI (D-013)

From process/design-basis.yaml.

Engineering model

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Drawing of the process (preview)Open the engineering model

The interactive model (drawings, streams, 3D) is made for larger screens.

Snapshot of c3ab348, cheme-as-code 1.6.0.

What goes in and out

In

  • ChlorineFeedstockfeed:CL2, dry chlorine gas from chlor-alkali-1, 0.980 kg per kg HCl
  • HydrogenFeedstockWet hydrogen from chlor-alkali-1 (feed:H2: 0.0464 kg wet gas = 0.0315 kg H2 per kg HCl), 10 mol-% excess
  • WaterFeedstockDemineralised water for the absorption (feed:DMW), 2.0 kg per kg HCl

Out

  • Hydrogen chlorideMain productHydrochloric acid 33 wt-% to storage, counted by mass of the acid (3.03 kg per kg HCl)
  • SteamCo-productSteam 1000 kPa(a) raised in the synthesis furnace, about 1.0 t per t HCl (0.665 kWh/kg HCl); allocation share 0 (D-013)
  • HydrogenEmissionExcess hydrogen vented after the tail gas scrubber, 2.9 g per kg HCl

Utilities: Electricity (Pumps, instruments and analysers (ASSUMED)), Cooling water (25/35 C (ASSUMED), absorber cooling)

Show in the process graph

Reactions

IdAs writtenReactionOther processes
H2_OX2 H2 + O2 ⇌ 2 H2O · Combustion of the oxygen in the chlorine feed with excess hydrogen2H2+O22H2O
HCL_SYNH2 + Cl2 ⇌ 2 HCl · Hydrogen chloride synthesis (chlorine burnt in hydrogen)H2+Cl22HCl

Each reaction's page has the conversion, heat of reaction, catalyst and sources this process states, next to those of other processes with the same reaction. All reactions

Life cycle assessment

–kg CO2-eqpartial, 5 data gaps

Climate change per 1 kg Hydrochloric acid 33 wt-%, gate-to-gate

No factors. No contribution is characterised, so no factor stands behind any number.

Main contributors
    Method and data
    Goal
    Preliminary gate-to-gate life cycle inventory of hydrochloric acid (33 wt-%) by direct synthesis from chlorine and hydrogen with steam recovery, for the concept stage: the foreground exchanges of the balanced flowsheet (D-006) per kg of contained HCl, ready to be linked to background datasets (chlor-alkali-1's chlorine and hydrogen first). No impact assessment is claimed.
    Functional unit
    1 kg Hydrochloric acid 33 wt-% (1 kg hydrogen chloride)
    Boundary
    gate-to-gate
    Allocation
    shares
    Characterisation
    Factors kept with the process · GWP100
    Data quality
    No factors
    Result
    partial screening carbon footprint · 5 data gaps
    ScenarioClimate change (kg CO2-eq)
    baselineno total (data gaps)

    Inventory per 1 kg Hydrochloric acid 33 wt-% (13 flows)

    FlowPhaseDirectionQuantityUnitProvenance
    Dry chlorine gas from chlor-alkali-1 (S42 there, 400 kPa(a))operationinput0.9803kgassumed
    Wet hydrogen from chlor-alkali-1 (S44 there, 140 kPa(a))operationinput0.04642kgassumed
    Demineralised water for absorptionoperationinput2.008kgassumed
    Electric power (AC, grid)operationinput0.001697kWhassumed
    Hydrochloric acid 33 wt-% to storageoperationoutput3.03kgassumed
    Tail gas scrubber vent to atmosphere (excess hydrogen)operationoutput0.003945kgassumed
    Steam 1000 kPa(a) raised in the synthesis furnace (export)operationoutput0.6652kWhassumed
    Cooling water returnoperationoutput0.5065kWhassumed
    Cl2 to the environmentoperationoutput0kgassumed
    H2 to the environmentoperationoutput0.002866kgassumed
    H2O to the environmentoperationoutput0.001079kgassumed
    HCl to the environmentoperationoutput0.0000003322kgassumed
    O2 to the environmentoperationoutput0kgassumed

    Computed by ChemE-as-Code from lca/README.md, lca/dataset.yaml, lca/factors.yaml, lca/gaps.csv, lca/inventory.csv, lca/lca.yaml, lca/mappings.yaml, lca/results.csv, lca/results.md.

    In the open LCI database (cheme-as-code-atlas-preview-c3ab348) as Hydrogen chloride, Hydrochloric acid 33 wt-% to storage.

    Download it for Brightway, openLCA and other tools.

    In the LCI database: system model, datasets and KPIs against the benchmarks

    In the LCI database

    System model
    attributional, cut-off (methodology 1.1.0)
    Allocation
    shares (deviation, from study) · product:HCLACID 100 %, product:STEAM 0 %
    Allocation findings
    none
    Change report
    Not available: this build has no change report against an earlier release.
    Dataset pages
    Hydrogen chloride, Hydrochloric acid 33 wt-% to storage

    KPI benchmark positions: not available (no benchmarked KPI for this process's datasets).

    Maturity and review

    Design maturity Concept (claimed): An idea or first flowsheet; numbers are rough. Concept PFD with closed mass, component and element balances (cheme validate, cheme process streams). The furnace outlet is calculated by cheme (conversion reactor, complete Cl2 and O2 conversion justified by K = 2.6e19 at 523 K) and cheme's reactor duty (2 268 kW released) equals the independent script's; the steam export follows from it with an assumed 3 % heat loss. cheme maturity reaches no level yet: the feeds are chlor-alkali-1's assumed product states, the absorber and scrubber are specified values, and energy closure is not evaluable in core (no property package covers Cl2/HCl gas or HCl-water). The preliminary gate-to-gate LCI closes in mass and elements; every background is a gap. Not reviewed. Main products and feeds are listed under chemistry with their chemicals registry entries (issue #251).

    Calculation maturity, from the checked evidenceNot assessed

    The process has no maturity report (cheme maturity, checks/maturity.json), so no calculation maturity is established.

    No level shownThe design maturity (Concept) is the manifest's claim, not evidence. A level appears here once the process's repository holds a current report from cheme maturity --write.

    Artifact completeness

    Which deliverables exist. They never raise a calculation maturity level: a drawing from unchecked numbers is still unchecked.

    Not reported without a maturity report.

    Independent review

    Not independently reviewed

    No independent engineering review yet. Automated checks passing is not a review.

    Set by people only. Reaching a calculation maturity level or passing automated checks is not an independent review or an approval.

    Where the evidence comes from
    Report
    processes/hydrogen-chloride-1/checks/maturity.json (not in the library)
    Design basis
    process/design-basis.yaml
    Method
    How ChemE-as-Code checks the levels (requirement by requirement)

    Open items

    0 open items · 0 closed

    New action itemNew engineering holdNew technical queryNew design changeAll issues

    Sources

    Engineering project
    Hydrogen chloride (synthesis burner and absorption) · cheme-as-code>=0.8
    Library version
    c3ab348 (process last changed in c3ab348)
    Drawings rendered by
    cheme 1.6.0 (pyDEXPI 2.1.0)
    Data
    Catalog record (JSON) · CC-BY-4.0
    Files
    View the files on GitHub · change history and authors

    References

    How to cite

    For the data, cite the Process Atlas paper; for the platform that builds and checks it, the ChemE-as-Code paper.

    Schweidtmann, A. M. & Weber, J. M. (2026, in preparation). Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title).

    For this process: "Hydrogen chloride synthesis burner and absorption (33 wt-% hydrochloric acid, steam recovery)", ChemE-as-Code process library, version c3ab348.

    BibTeX
    @unpublished{schweidtmann_process_atlas,
  author = {Schweidtmann, Artur M. and Weber, Jana M.},
  title = {{Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title)}},
  year = {2026},
  url = {https://atlas.cheme-as-code.org},
  note = {in preparation}
}

    Schweidtmann, A. M. (2026, in preparation). ChemE-as-Code: An Open-Source Platform for AI-Accelerated Chemical Process Engineering (working title).

    BibTeX
    @unpublished{schweidtmann_cheme_as_code,
  author = {Schweidtmann, Artur M.},
  title = {{ChemE-as-Code: An Open-Source Platform for AI-Accelerated Chemical Process Engineering (working title)}},
  year = {2026},
  url = {https://cheme-as-code.org},
  note = {in preparation}
}