{
  "authors": [],
  "basis": {
    "capacity": "50 kt/a isobutene (ASSUMED)",
    "location": "generic (not chosen)",
    "operating_hours_per_year": 8000
  },
  "benchmarks": [],
  "chemistry": {
    "inputs": [
      {
        "chemical": "methyl-tert-butyl-ether",
        "grade": null,
        "note": "feed:MTBEF: fresh MTBE from an MTBE unit or terminal, 1.587 kg/kg isobutene before allocation",
        "role": "feedstock"
      },
      {
        "chemical": "water",
        "grade": null,
        "inventory_key": "feed:DMW",
        "note": "Demineralised wash-water make-up",
        "role": "feedstock"
      }
    ],
    "outputs": [
      {
        "chemical": "isobutene",
        "grade": null,
        "inventory_key": "product:IBP",
        "note": "High-purity isobutene to storage",
        "role": "main-product"
      },
      {
        "chemical": "methanol",
        "grade": null,
        "inventory_key": "product:MEOHP",
        "note": "Recovered methanol, 0.567 kg/kg isobutene",
        "role": "co-product"
      },
      {
        "chemical": "wastewater",
        "grade": null,
        "inventory_key": "product:WW",
        "note": "Wash-water purge, ~100 mg/kg methanol",
        "role": "waste"
      }
    ],
    "utilities": [
      {
        "chemical": "electricity",
        "grade": null,
        "inventory_key": "feed:POWER",
        "note": "Pumps and the H-101 combustion-air fan and hot-oil pump (ASSUMED electric drives)",
        "role": "utility"
      },
      {
        "chemical": "steam",
        "grade": null,
        "inventory_key": "feed:MPS",
        "note": "MP steam 1500 kPa(a), C-101 reboiler",
        "role": "utility"
      },
      {
        "chemical": "steam",
        "grade": null,
        "inventory_key": "feed:LPS",
        "note": "LP steam 450 kPa(a), C-201, C-301, C-402 and C-403 reboilers",
        "role": "utility"
      },
      {
        "chemical": "cooling-water",
        "grade": null,
        "inventory_key": "product:CW",
        "note": "25/35 C (ASSUMED)",
        "role": "utility"
      }
    ]
  },
  "description": "Fresh MTBE (a boundary feed) and the MTBE/methanol recycle are freed of heavy ends in the\nMTBE column, whose vapour overhead is superheated against the reactor effluent and in a fired\nhot-oil heater and cracked at 553 K and about 0.9 MPa in a heated multitubular reactor over\nan acidic silica-alumina type catalyst (MTBE conversion 0.90 per pass, assumed inside the\nrange of US 8,633,345 B2). Dimethyl ether and C8 dimers form as by-products. The condensed\neffluent is split in the isobutene column: crude isobutene overhead, methanol and\nunconverted MTBE as bottoms, from which the methanol column recycles the MTBE/methanol\nazeotrope and leaves methanol. Methanol is washed out of the crude isobutene with water;\nthe drying column removes DME and water overhead and gives 99.97 wt% isobutene as bottoms\n(pure MTBE feed: the linear butenes and C5 that technical MTBE brings, which decide the\npolymer grade in a real plant, are not modelled; DESIGN.md D-003).\nThe wash water is regenerated in a methanol/water column.\n\nAll values are concept estimates. The column, wash and duty values come from an independent\nscript with specified component splits and shortcut duties from pure-component data; core\ncannot qualify the polar, azeotropic MTBE/methanol/water/C4 system yet. See\nDESIGN.md of the engineering files for every assumption and gated step. Designed\nindependently from the open patent literature; no licensor data are used.\n",
  "design_basis": {
    "assumptions": [
      "ASSUMED gas-phase cracking over an acidic silica-alumina type catalyst in a heated multitubular reactor at 553 K, 900 kPa(a) inlet (inside 150-500 C and 0.05-2 MPa of US 8,633,345 B2; D-004).",
      "ASSUMED MTBE conversion 0.90 per pass (patent's preferred range 85-95 %); per kmol MTBE converted 0.010 kmol DME and 0.001 kmol C8 dimer: a conversion/selectivity model, not kinetics (D-005).",
      "ASSUMED separations by component split specifications (D-007), shortcut duties from pure-component data (D-006); not a rigorous simulation.",
      "ASSUMED pure MTBE feed: no MSBE (source of linear butenes), TBA, C5 or water in the feed (D-003).",
      "ASSUMED pump efficiency 0.6; fans, the hot-oil circulation and instrument air not counted (D-009).",
      "All flows, temperatures and duties are concept estimates; accuracy not stated."
    ],
    "source": "process/design-basis.yaml"
  },
  "engineering": {
    "description": "High-purity isobutene by gas-phase MTBE cracking (50 kt/a, concept): MTBE as boundary feed, methanol co-product (issue process-library#165)",
    "name": "Isobutene (MTBE cracking)",
    "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",
      "distillation",
      "extraction"
    ]
  },
  "families": [
    "olefins"
  ],
  "gap_count": 1,
  "gates": null,
  "id": "isobutene-1",
  "issues": {
    "closed_count": 0,
    "list_url": "https://github.com/ChemE-as-Code/process-library/issues?q=is%3Aissue%20label%3A%22process%3Aisobutene-1%22",
    "new": {
      "action": "https://github.com/ChemE-as-Code/process-library/issues/new?template=1-action-item.yml&labels=process%3Aisobutene-1&process=isobutene-1",
      "change": "https://github.com/ChemE-as-Code/process-library/issues/new?template=4-design-change.yml&labels=process%3Aisobutene-1&process=isobutene-1",
      "hold": "https://github.com/ChemE-as-Code/process-library/issues/new?template=2-engineering-hold.yml&labels=process%3Aisobutene-1&process=isobutene-1",
      "process": "https://github.com/ChemE-as-Code/process-library/issues/new?template=6-process-development.yml&labels=process%3Aisobutene-1&process=isobutene-1",
      "tq": "https://github.com/ChemE-as-Code/process-library/issues/new?template=3-technical-query.yml&labels=process%3Aisobutene-1&process=isobutene-1",
      "tracker": "https://github.com/ChemE-as-Code/process-library/issues/new?template=7-process-tracker.yml&labels=process%3Aisobutene-1&process=isobutene-1"
    },
    "open": [],
    "open_by_gate": {},
    "open_count": 0,
    "private": false,
    "repository": "ChemE-as-Code/process-library"
  },
  "keywords": [
    "isobutene",
    "isobutylene",
    "MTBE",
    "methyl tert-butyl ether",
    "ether cracking",
    "back-cracking",
    "methanol",
    "dimethyl ether",
    "diisobutene",
    "water wash",
    "distillation"
  ],
  "lca": null,
  "lci_gaps": [
    {
      "dataset": "isobutene-by-mtbe-cracking-50-kt-a-gas-phase-cleavage",
      "key": "feed:MTBEF",
      "link": "technosphere",
      "type": "input"
    }
  ],
  "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": "US 8,633,345 B2 (2014) Process for preparing isobutene by cleaving MTBE-containing mixtures (Evonik Oxeno): catalyst, reactor conditions, conversion range, column and wash ranges, Example 2 stream data",
      "url": "https://patents.google.com/patent/US8633345B2/en"
    },
    {
      "doi": "10.1002/14356007.a04_483.pub3",
      "title": "Ullmann's Encyclopedia of Industrial Chemistry: Butenes (route context; not audited for numbers)"
    },
    {
      "title": "Cox, J.D., Wagman, D.D., Medvedev, V.A. (1989) CODATA Key Values for Thermodynamics. Hemisphere (CO2 and H2O formation enthalpies for the LHV)"
    },
    {
      "title": "Bell, C. et al. chemicals and thermo (Python): formation enthalpies, heat capacities, latent heats and vapour pressures used in the balance",
      "url": "https://github.com/CalebBell/chemicals"
    }
  ],
  "repository": {
    "access": "public",
    "path": "processes/isobutene-1",
    "url": "https://github.com/ChemE-as-Code/process-library"
  },
  "representations": [
    {
      "bytes": 42097,
      "id": "BFD",
      "kind": "bfd",
      "preview": "artifacts/isobutene-1/BFD.svg",
      "source": "process/BFD.xml",
      "status": "preview",
      "title": "Block flow diagram"
    },
    {
      "bytes": 175577,
      "id": "PFD",
      "kind": "pfd",
      "preview": "artifacts/isobutene-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": "High-purity isobutene by gas-phase cracking of MTBE over an acidic catalyst, with MTBE recycle, a water wash for methanol, a drying/DME column and methanol recovery; methanol is a co-product. Concept stage, assumed basis, preliminary LCI (foreground inventory only).",
  "title": "Isobutene by MTBE cracking (50 kt/a, gas-phase cleavage)",
  "validation": {
    "notes": "Concept PFD with closed mass, component and element balances (cheme validate, cheme process streams: every block and step ok) and a closed LCI mass and element balance (cheme assess lca --coverage). cheme maturity reaches no level: the MTBE feed and the capacity are assumed, and the columns and the wash are specified component splits from an independent script (scripts/ib_balance.py) whose shortcut duties rest on pure-component data and ideal Raoult bubble points; no qualified property package covers MTBE / methanol / water / C4. The reactor outlet is calculated by cheme (conversion reactor with assumed conversion and selectivities inside the patent ranges); cheme's ideal-gas reactor duty (1970.08 kW) reproduces the script's 1970.1 kW. The LCI is a foreground inventory with every background open (8 gaps): no impact result, and no LCA result passed to the catalog (lca.source none). 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/isobutene-1/",
    "stale": false,
    "tool": "cheme-as-code 1.6.0",
    "views": [
      "checks",
      "streams"
    ]
  }
}