Ethylene and propylene by ethane steam cracking (1000 kt/a ethylene, concept)

Ethane steam cracking with ethane and propane recycle, quench, cracked-gas compression with caustic wash and drying, front-end demethaniser, tail-end acetylene hydrogenation and C2/C3 splitters to polymer-grade ethylene and propylene, crude C4 and pyrolysis gasoline. Concept stage, assumed basis, preliminary gate-to-gate LCI with unmapped backgrounds.

Calculation maturity: not assessedDesign maturity: Concept (research)Not independently reviewedOlefins Report 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

Purity ethane and the recycled ethane are cracked with dilution steam at a coil outlet of 840 C; the recycled propane has its own coil. The furnace is a conversion model that reproduces the once-through ethane and propane yields of the EU BREF on large volume organic chemicals (2017, Table 3.3): a sourced yield model, not kinetics. The cracked gas raises SHP steam in the transfer line exchangers, is quenched with water (the condensate becomes dilution steam again), compressed in five stages with a caustic wash, dried and separated at low temperature: demethaniser (tail gas and hydrogen to the furnace fuel), deethaniser, acetylene converter, C2 splitter, depropaniser, MAPD converter, C3 splitter and debutaniser. The tail gas and a natural-gas make-up fire the furnaces.

The separations are specified splits from an independent balance script, and the energy figures rest on ideal-gas enthalpies: core has no qualified property package for C2+ hydrocarbon mixtures yet. See DESIGN.md for every assumption and gated step.

Capacity: 1000 kt/a polymer-grade ethylene (ASSUMED)
Operation: 8,000 h/a
Location: generic (not chosen)
Engineering gates: Concept and feasibility (no results yet)
Maintainers: Artur Schweidtmann

Design basis and assumptions (5)

Furnace: once-through yields of BREF LVOC 2017 Table 3.3 (ethane: 70 % conversion; propane column for the C3 recycle coil) as a conversion model, coil outlet 840 C, 200 kPa(a), 0.30 kg steam/kg hydrocarbon (D-004, D-005). Sourced yields, not kinetics.
Separations are specified splits (recoveries, purities) in scripts/balance.py, not rigorous columns (D-006, D-010).
Firebox: complete combustion, 15 % excess air, stack 120 C, casing loss 1.5 % of the LHV (D-013).
Compressor isentropic efficiency 0.78; refrigeration COP 60 % of Carnot (D-008, D-014).
All values are concept estimates; accuracy not stated.

From process/design-basis.yaml.

Engineering model

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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

EthaneFeedstockfeed:ETHANE: purity ethane by pipeline, 1.27 kg/kg ethylene (unallocated)
MethaneFeedstockfeed:NATGAS: natural gas make-up to the fuel header, taken as methane
Sodium hydroxideFeedstockfeed:CAUSTIC: fresh caustic soda solution 10 wt%, counted by mass of the solution
AirFeedstockCombustion air of the cracking furnaces
WaterFeedstockBoiler feed water make-up to the dilution steam system

Out

EthyleneMain productPolymer-grade ethylene
PropyleneCo-productPolymer-grade propylene
Crude C4 cutCo-productCrude C4 cut
Pyrolysis gasolineCo-productPyrolysis gasoline (C5/C6 cut)
SteamCo-productSHP steam 11500 kPa(a), 520 C, raised in the TLEs and convection sections (ASSUMED export, D-015); outside the mass allocation and without a burden, so the fuel and CO2 that raise it stay with the hydrocarbon products
Carbon dioxideEmissionFossil CO2 of the furnace flue gas: 0.472 kg/kg ethylene unallocated (59.1 t/h over 125 t/h ethylene), 0.433 kg/kg ethylene with mass allocation (ethylene share 91.6 %). Both are gross: they include the fuel that preheats and superheats the exported SHP steam (product:HPS, about a third of the fired duty), which carries no burden (D-015, D-016)
WastewaterWasteProcess water blowdown; the spent caustic (product:SPENTCAUSTIC) is a second wastewater

Utilities: Electricity (Cracked gas and refrigeration compressor drives (ASSUMED electric, D-015)), Steam (MP steam 1800 kPa(a) to the dilution steam generator), Steam (LP steam 450 kPa(a) to the column reboilers), Cooling water (25/35 C (ASSUMED))

Show in the process graph

Reactions

Id	As written	Reaction	Other processes
AH_C2H4	C2H2 + H2 → C2H4	C₂H₂+H₂givesC₂H₄
AH_C2H6	C2H2 + 2 H2 → C2H6	C₂H₂+2H₂givesC₂H₆
C2H6_C2H2	C2H6 → C2H2 + 2 H2	C₂H₆givesC₂H₂+2H₂
C2H6_C3H4	3 C2H6 → 2 C3H4 + 5 H2	3C₂H₆gives2C₃H₄+5H₂
C2H6_C3H6	3 C2H6 → 2 C3H6 + 3 H2	3C₂H₆gives2C₃H₆+3H₂
C2H6_C3H8	3 C2H6 → 2 C3H8 + H2	3C₂H₆gives2C₃H₈+H₂
C2H6_C4H10	2 C2H6 → C4H10 + H2	2C₂H₆givesC₄H₁₀+H₂
C2H6_C4H6	2 C2H6 → C4H6 + 3 H2	2C₂H₆givesC₄H₆+3H₂
C2H6_C4H8	2 C2H6 → C4H8 + 2 H2	2C₂H₆givesC₄H₈+2H₂
C2H6_C6H6	3 C2H6 → C6H6 + 6 H2	3C₂H₆givesC₆H₆+6H₂
C2H6_DH	C2H6 ⇌ C2H4 + H2	C₂H₆in equilibrium withC₂H₄+H₂
C2H6_HGL	C2H6 + H2 → 2 CH4	C₂H₆+H₂gives2CH₄
C2H6_TO_C3	2 C2H6 → C3H8 + CH4	2C₂H₆givesC₃H₈+CH₄
C3H8_C2H4	C3H8 → C2H4 + CH4	C₃H₈givesC₂H₄+CH₄
C3H8_DH	C3H8 → C3H6 + H2	C₃H₈givesC₃H₆+H₂
C3H8_HGL	C3H8 + H2 → C2H6 + CH4	C₃H₈+H₂givesC₂H₆+CH₄
CAUSTIC	CO2 + 2 NaOH → Na2CO3 + H2O	CO₂+2NaOHgivesNa₂CO₃+H₂O	1 other process
COMB_C2H4	C2H4 + 3 O2 → 2 CO2 + 2 H2O	C₂H₄+3O₂gives2CO₂+2H₂O	3 other processes
COMB_C2H6	C2H6 + 3.5 O2 → 2 CO2 + 3 H2O	2C₂H₆+7O₂gives4CO₂+6H₂O	3 other processes
COMB_CH4	CH4 + 2 O2 → CO2 + 2 H2O	CH₄+2O₂givesCO₂+2H₂O	9 other processes
COMB_H2	H2 + 0.5 O2 → H2O	2H₂+O₂gives2H₂O	5 other processes
MAPD_C3H6	C3H4 + H2 → C3H6	C₃H₄+H₂givesC₃H₆
MAPD_C3H8	C3H4 + 2 H2 → C3H8	C₃H₄+2H₂givesC₃H₈

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

0.433kg CO2-eqPreliminarypartial, 12 data gaps

Climate change per 1 kg Polymer-grade ethylene, gate-to-gate

Main contributors

CO2 to the environment99.8 %
CH4 to the environment0.11 %
N2O to the environment (estimated)0.1 %

Contributions, baseline

Each flow of the inventory into its phase, the phases into the functional unit; band widths are impacts. Hatched: a credit.

Method and data

Goal: Preliminary gate-to-gate life cycle inventory of polymer-grade ethylene from ethane steam cracking at concept stage: every foreground exchange per kg ethylene from the balanced flowsheet, to be linked to background datasets later (DESIGN.md D-016).
Functional unit: 1 kg Polymer-grade ethylene (1 kg ethylene)
Boundary: gate-to-gate
Characterisation: Factors kept with the process · GWP100
Data quality: Published factors
Result: partial screening carbon footprint · 12 data gaps

Scenario	Climate change (kg CO2-eq)
baseline	0.4335

Inventory per 1 kg Polymer-grade ethylene (29 flows)

Flow	Phase	Direction	Quantity	Unit	Provenance
Purity ethane feed (pipeline)	operation	input	1.161	kg	assumed
Natural gas make-up to the fuel header	operation	input	0.07051	kg	assumed
Combustion air	operation	input	5.775	kg	assumed
Boiler feed water make-up to the dilution steam system	operation	input	0.01533	kg	assumed
Fresh caustic soda solution 10 wt%	operation	input	0.09175	kg	assumed
Electric power (machine drives, D-015)	operation	input	0.871	kWh	assumed
MP steam 1800 kPa(a) to the dilution steam generator	operation	input	0.3389	kWh	assumed
LP steam 450 kPa(a) to the column reboilers	operation	input	0.3361	kWh	assumed
Polymer-grade ethylene	operation	output	1	kg	assumed
Polymer-grade propylene	operation	output	0.02615	kg	assumed
Crude C4 cut	operation	output	0.03477	kg	assumed
Pyrolysis gasoline (C5/C6 cut)	operation	output	0.0313	kg	assumed
Cracking furnace flue gas to atmosphere	operation	output	6.004	kg	calculated
Process water blowdown to wastewater treatment	operation	output	0.01533	kg	assumed
Spent caustic to treatment	operation	output	0.09511	kg	assumed
SHP steam raised in the TLEs and convection sections (11500 kPa(a), 520 C)	operation	output	2.47	kWh	assumed
Cooling water return	operation	output	2.73	kWh	assumed
C2H4 to the environment	operation	output	0	kg	calculated
C2H6 to the environment	operation	output	0	kg	calculated
CH4 to the environment	operation	output	0.00001611	kg	estimated
CO2 to the environment	operation	output	0.4326	kg	calculated
H2 to the environment	operation	output	0	kg	calculated
H2O to the environment	operation	output	0.9645	kg	calculated
N2 to the environment	operation	output	4.431	kg	calculated
O2 to the environment	operation	output	0.1755	kg	calculated
NOx to the environment (estimated)	operation	output	0.0003855	kg	estimated
CO to the environment (estimated)	operation	output	0.0001927	kg	estimated
PM to the environment (estimated)	operation	output	0.00002739	kg	estimated
N2O to the environment (estimated)	operation	output	0.000001611	kg	estimated

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 Polymer-grade ethylene Preliminary; Polymer-grade propylene Preliminary; Crude C4 cut Preliminary; Pyrolysis gasoline (C5/C6 cut) Preliminary.

Download it for Brightway, openLCA and other tools.

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

In the LCI database

Status: Preliminary 4 unmapped exchanges. Some exchanges have no background mapping yet: they are exported unlinked and count no burden, so the inventory is incomplete.
System model: attributional, cut-off (methodology 1.1.0)
Allocation: mass (deviation, from study) · product:CRUDEC4 3.2 %, product:ETHYLENE 91.6 %, product:PROPYLENE 2.4 %, product:PYGAS 2.9 %
Allocation findings: none
Change report: Not available: this build has no change report against an earlier release.
Dataset pages: Crude C4 cut Preliminary · Polymer-grade ethylene Preliminary · Polymer-grade propylene Preliminary · Pyrolysis gasoline (C5/C6 cut) Preliminary

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: 0 errors, 0 warnings). Furnace, hydrogenation reactors and firebox outlets are calculated by cheme (conversion reactors; furnace conversions derived from the BREF LVOC 2017 Table 3.3 yields). Capacity, feed composition, splits, purities, efficiencies and utility levels are ASSUMED; separations and duties come from scripts/balance.py on ideal-gas enthalpies (no qualified property package for the C2+ hydrocarbons), so the energy balance is not evaluable in core beyond the reactor duties, which cheme process reactors reproduces. The preliminary gate-to-gate LCI closes in mass, elements and carbon by origin, with every background unmapped (gaps). Not reviewed. Main products and feeds are listed under chemistry with their chemicals registry entries (issue #251). cheme maturity: calculation maturity none (sourced boundary fails: capacity and feed are ASSUMED; balanced model basis fails: the splits and conversions of H102, T201, D210, T310, D320, V402, R501 and R601 are unsourced). concept is claimed as the lowest level of the manifest; the warning cheme.maturity-claim-exceeds is acknowledged. The refrigeration power is a conservative upper estimate (D-014).

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/ethylene-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 item New engineering hold New technical query New design change All issues

Sources

Engineering project: Ethylene and propylene by steam cracking · 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

Falcke, H. et al. (2017) Best Available Techniques (BAT) Reference Document for the Production of Large Volume Organic Chemicals. JRC Science for Policy Report EUR 28882 EN (JRC109279), chapter 3 Lower olefins · doi:10.2760/77304
Zimmermann, H.; Walzl, R. Ethylene. Ullmann's Encyclopedia of Industrial Chemistry (lead from issue #176; not audited in this run) · doi:10.1002/14356007.a10_045.pub2
IPCC (2006) 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Vol. 2 Energy, Ch. 2 Stationary Combustion

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: "Ethylene and propylene by ethane steam cracking (1000 kt/a ethylene, concept)", 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).