{
  "authors": [],
  "basis": {
    "capacity": "50 kt/a acetic anhydride 99.5 wt% (ASSUMED)",
    "location": "generic (not chosen)",
    "operating_hours_per_year": 8000
  },
  "benchmarks": [],
  "chemistry": {
    "inputs": [
      {
        "chemical": "acetic-acid",
        "grade": null,
        "note": "feed:AA: glacial acetic acid, the main feed, 1.246 kg/kg product (e.g. from acetic-acid-1, D-003)",
        "role": "feedstock"
      },
      {
        "chemical": "triethyl-phosphate",
        "grade": null,
        "note": "feed:TEP: cracking catalyst triethyl phosphate, 1.6 g/kg",
        "role": "feedstock"
      },
      {
        "chemical": "ammonia",
        "grade": null,
        "note": "feed:NH3: ammonia, the catalyst neutraliser, 0.3 g/kg (e.g. from ammonia-1)",
        "role": "feedstock"
      },
      {
        "chemical": "methane",
        "grade": null,
        "inventory_key": "feed:NG",
        "note": "Natural gas to the cracking furnace, taken as methane (D-010)",
        "role": "feedstock"
      },
      {
        "chemical": "air",
        "grade": null,
        "inventory_key": "feed:AIR",
        "note": "Combustion air of the furnace",
        "role": "feedstock"
      }
    ],
    "outputs": [
      {
        "chemical": "acetic-anhydride",
        "grade": null,
        "inventory_key": "product:AC2O",
        "note": "Acetic anhydride 99.5 wt% to storage",
        "role": "main-product"
      },
      {
        "chemical": "wastewater",
        "grade": null,
        "inventory_key": "product:WW",
        "note": "Wastewater of the dilute acid recovery, about 0.65 wt% acetic acid",
        "role": "waste"
      },
      {
        "chemical": "carbon-dioxide",
        "grade": null,
        "inventory_key": "product:STACK",
        "note": "CO2 of the furnace flue gas (natural gas and vent gas burned), 0.195 kg/kg product",
        "role": "emission"
      }
    ],
    "utilities": [
      {
        "chemical": "electricity",
        "grade": null,
        "inventory_key": "feed:POWER",
        "note": "Vent vacuum pump and absorber circulation pumps",
        "role": "utility"
      },
      {
        "chemical": "steam",
        "grade": null,
        "note": "LP steam 450 kPa(a), vaporiser and dilute acid recovery (feed:LPS); MP steam 1500 kPa(a), distillation reboilers (feed:MPS); both in kWh of heat delivered",
        "role": "utility"
      },
      {
        "chemical": "cooling-water",
        "grade": null,
        "inventory_key": "product:CW",
        "note": "25/35 C (ASSUMED)",
        "role": "utility"
      },
      {
        "chemical": "chilled-water",
        "grade": null,
        "inventory_key": "product:BRINE",
        "note": "Brine at -10 C on the last cracked-gas condensers; the registry has chilled water, not brine (closest entry)",
        "role": "utility"
      }
    ]
  },
  "description": "Glacial acetic acid (a boundary feed) is vaporised and cracked in a fired tubular furnace at\n700 C and about 36 kPa(a) with triethyl phosphate; ammonia neutralises the catalyst at the\ncoil outlet. The cracked gas is condensed to -5 C (cooling water, then brine), which removes\nthe reaction water and the unconverted acid as dilute acid. The ketene is absorbed and\nreacted in acetic acid to crude anhydride, which an acid column and an anhydride column\nrefine; the dilute acid is recovered (extraction and azeotropic dehydration, lumped) and\nrecycled, and the absorber vent gas is burned in the furnace with natural gas.\n\nThe cracking conversion (0.84) and ketene selectivity (0.92) are the example of a published\npatent (US 4,455,439); the absorber, column and acid-recovery performances, all duties and\nthe capacity are assumed concept values from an independent balance script. See DESIGN.md of\nthe engineering files for every assumption and gated step.\n",
  "design_basis": {
    "assumptions": [
      "Cracking at 700 C and 36 kPa(a) at the coil outlet with triethyl phosphate, acetic acid conversion 0.84 per pass and 0.92 kmol ketene per kmol acid converted: the example of US 4,455,439 (D-005). A sourced conversion model, not kinetics.",
      "ASSUMED split of the 8 % cracking loss: half acid decomposition to CH4 + CO2, half ketene decomposition to ethylene + CO (D-005).",
      "Cracked gas condensed to -5 C at 27 kPa(a), cooling water then -10 C brine (US 4,455,439 example); the ketene gas leaves dry (ASSUMED, D-006).",
      "ASSUMED absorber: 99 % of the ketene absorbed, 99 % of it to anhydride and 1 % to heavy ends; crude 88 wt% anhydride; vent acid vapour neglected (D-007).",
      "ASSUMED distillation: acid column distillate 98 wt% acid recycled to the absorbers, reflux ratio 3; anhydride column reflux ratio 1, residue 50 wt% anhydride (D-008).",
      "ASSUMED dilute acid recovery: 99 % of the acid recovered at 99.8 wt%, 3.0 MJ LP steam per kg water in the dilute acid (D-009).",
      "ASSUMED firebox: complete combustion, 15 % excess air, stack 443 K, 2 % radiation loss (D-010).",
      "All flows and duties are concept estimates from scripts/ac2o_balance.py; no property method for these mixtures is qualified by ChemE-as-Code; accuracy not stated."
    ],
    "source": "process/design-basis.yaml"
  },
  "engineering": {
    "description": "",
    "name": "Acetic anhydride (ketene route)",
    "requires": "cheme-as-code>=0.8",
    "stage": "concept",
    "stages": [
      {
        "id": "concept",
        "title": "Concept and feasibility"
      },
      {
        "id": "basic",
        "title": "Basic engineering"
      },
      {
        "id": "detail",
        "title": "Detail engineering"
      }
    ],
    "tool": "plantcode"
  },
  "facets": {
    "feedstock_basis": [
      "fossil"
    ],
    "product_classes": [
      "chemicals"
    ],
    "region": "generic",
    "unit_operations": [
      "reaction",
      "heat-exchange",
      "absorption",
      "distillation",
      "extraction"
    ]
  },
  "families": [
    "oxygenates"
  ],
  "gap_count": 4,
  "gates": null,
  "id": "acetic-anhydride-1",
  "issues": {
    "closed_count": 0,
    "list_url": "https://github.com/ChemE-as-Code/process-library/issues?q=is%3Aissue%20label%3A%22process%3Aacetic-anhydride-1%22",
    "new": {
      "action": "https://github.com/ChemE-as-Code/process-library/issues/new?template=1-action-item.yml&labels=process%3Aacetic-anhydride-1&process=acetic-anhydride-1",
      "change": "https://github.com/ChemE-as-Code/process-library/issues/new?template=4-design-change.yml&labels=process%3Aacetic-anhydride-1&process=acetic-anhydride-1",
      "hold": "https://github.com/ChemE-as-Code/process-library/issues/new?template=2-engineering-hold.yml&labels=process%3Aacetic-anhydride-1&process=acetic-anhydride-1",
      "process": "https://github.com/ChemE-as-Code/process-library/issues/new?template=6-process-development.yml&labels=process%3Aacetic-anhydride-1&process=acetic-anhydride-1",
      "tq": "https://github.com/ChemE-as-Code/process-library/issues/new?template=3-technical-query.yml&labels=process%3Aacetic-anhydride-1&process=acetic-anhydride-1",
      "tracker": "https://github.com/ChemE-as-Code/process-library/issues/new?template=7-process-tracker.yml&labels=process%3Aacetic-anhydride-1&process=acetic-anhydride-1"
    },
    "open": [],
    "open_by_gate": {},
    "open_count": 0,
    "private": false,
    "repository": "ChemE-as-Code/process-library"
  },
  "keywords": [
    "acetic anhydride",
    "ketene",
    "acetic acid",
    "pyrolysis",
    "cracking furnace",
    "triethyl phosphate",
    "absorption",
    "distillation",
    "dilute acid recovery"
  ],
  "lca": null,
  "lci_gaps": [
    {
      "dataset": "acetic-anhydride-by-acetic-acid-cracking-to-ketene-50-kt-a-concept",
      "key": "feed:TEP",
      "link": "technosphere",
      "type": "input"
    },
    {
      "dataset": "acetic-anhydride-by-acetic-acid-cracking-to-ketene-50-kt-a-concept",
      "key": "product:RESIDUE",
      "link": "technosphere",
      "type": "output"
    },
    {
      "dataset": "acetic-anhydride-by-acetic-acid-cracking-to-ketene-50-kt-a-concept",
      "key": "product:BRINE",
      "link": "technosphere",
      "type": "output"
    },
    {
      "dataset": "acetic-anhydride-by-acetic-acid-cracking-to-ketene-50-kt-a-concept",
      "key": "emission:KET",
      "link": "biosphere",
      "type": "emission"
    }
  ],
  "maintainers": [
    {
      "name": "Artur Schweidtmann"
    }
  ],
  "maturity": "concept",
  "preliminary": true,
  "provenance": {
    "library_commit": "c3ab3488c602bc797fdc98feffd4578375150dd0",
    "previews": {
      "sheets": [
        "BFD",
        "PFD"
      ],
      "source_commit": "c3ab3488c602bc797fdc98feffd4578375150dd0",
      "tool": "cheme 1.6.0 (pyDEXPI 2.1.0)"
    },
    "previews_stale": false,
    "source_commit": "c3ab3488c602bc797fdc98feffd4578375150dd0"
  },
  "publication": {
    "license": "CC-BY-4.0",
    "status": "public"
  },
  "references": [
    {
      "title": "Hoechst AG (1984) Process for the preparation of ketene, US 4,455,439 (Example: cracking conditions, conversion, ketene yield, condensate)",
      "url": "https://patents.google.com/patent/US4455439A/en"
    },
    {
      "title": "Celanese (2014) Processes for preparing acetic anhydride, US 8,653,303 B2 (catalyst rate, absorber conditions, heat of reaction, crude composition)",
      "url": "https://patents.google.com/patent/US8653303B2/en"
    },
    {
      "title": "Padmanabhan, N., Deshpande, P.K., Kuloor, N.R. (1968) Catalytic cracking of acetic acid to acetic anhydride. I&EC Process Design and Development 7(4) 511-516"
    },
    {
      "doi": "10.1002/14356007.a01_065",
      "title": "Arpe, H.-J. et al. Acetic Anhydride and Mixed Fatty Acid Anhydrides. Ullmann's Encyclopedia of Industrial Chemistry (route reference lead, not audited in this run)"
    }
  ],
  "repository": {
    "access": "public",
    "path": "processes/acetic-anhydride-1",
    "url": "https://github.com/ChemE-as-Code/process-library"
  },
  "representations": [
    {
      "bytes": 41121,
      "id": "BFD",
      "kind": "bfd",
      "preview": "artifacts/acetic-anhydride-1/BFD.svg",
      "source": "process/BFD.xml",
      "status": "preview",
      "title": "Block flow diagram"
    },
    {
      "bytes": 181058,
      "id": "PFD",
      "kind": "pfd",
      "preview": "artifacts/acetic-anhydride-1/PFD.svg",
      "source": "process/PFD.xml",
      "status": "preview",
      "title": "Process flow diagram"
    },
    {
      "id": "process-model",
      "kind": "process-model",
      "source": "process/flowsheet.yaml",
      "status": "viewer",
      "title": "Flowsheet and stream table"
    },
    {
      "id": "equipment-list",
      "kind": "equipment-list",
      "source": "equipment/equipment-list.yaml",
      "status": "viewer",
      "title": "Equipment list"
    },
    {
      "id": "lca",
      "kind": "lca",
      "source": "lca/lca.yaml",
      "status": "viewer",
      "title": "Life cycle assessment"
    }
  ],
  "summary": "Acetic acid cracked to ketene at 700 C under vacuum with a triethyl phosphate catalyst, ketene absorbed and reacted in acetic acid, crude anhydride distilled to 99.5 wt%; the dilute acid is recovered and the vent gas fuels the furnace. Concept stage, assumed basis.",
  "title": "Acetic anhydride by the ketene route (acetic acid cracking, 50 kt/a, concept)",
  "validation": {
    "notes": "Concept PFD with closed mass, component and element balances on every block and step (cheme validate, cheme process streams; overall 14 892 kg/h in and out). The cracking coil, absorber and firebox outlets are calculated by cheme conversion reactors; the separator, column and acid-recovery outlets, all temperatures, pressures and duties are ASSUMED values from scripts/ac2o_balance.py. Energy closure is not evaluable in core (no property package covers acetic acid, ketene, anhydride and water); the script closes it on its own property data. Preliminary gate-to-gate LCI with every background unmapped (11 gaps). Not reviewed. Main products and feeds are listed under chemistry with their chemicals registry entries (issue #251).",
    "status": "unreviewed"
  },
  "viewer": {
    "commit": "c3ab3488c602bc797fdc98feffd4578375150dd0",
    "dirty": false,
    "sheets": [
      "process/BFD.xml",
      "process/PFD.xml"
    ],
    "skipped": [],
    "snapshot": "snapshots/acetic-anhydride-1/",
    "stale": false,
    "tool": "cheme-as-code 1.6.0",
    "views": [
      "checks",
      "streams"
    ]
  }
}