Choose lignin extraction rate and destination while preserving recovery-boiler, steam, power, kiln and self-sufficiency constraints.
Historical independent study · kraft biorefinery
Extract lignin only while the pulp mill still closes its energy balance
Find the extraction-rate frontier between saleable lignin, recovery capacity, kiln substitution, dryer duty and electricity export.
Black liquorPrecipitateSeparateWashDryGranulateEnergy system
Decision model
A bounded question with a complete plant consequence.
Pulping abstraction and black liquor through lignin separation, washing, drying/granulation, remaining-liquor recovery, steam turbine and lime-kiln fuel branch.
Equations and accounting rules
Dry solids, lignin, inorganic chemical and water balancesBlack-liquor heating value after extractionSteam generation, header demand and turbine powerKiln fossil displacement and whole-site marginBase, alternative and stress cases
- 0–25% lignin extraction
- Powder versus granulate
- Sale versus kiln substitution
- High power price and boiler bottleneck
Engineering brief
Model the complete decision, not an isolated unit operation.
Stora Enso publicly documented integrated kraft-lignin extraction, drying, granulation and potential lime-kiln use at Sunila. Stora Enso also states that Sunila pulp and lignin production ended in 2023.
This is therefore an explicitly historical process study—not a current operating-site model. Black-liquor composition, extraction chemistry, boiler limits and economics remain assumptions.
01 · Model basis
What the Acatian model needs to resolve
Inputs, mechanisms, limits and outputs remain reviewable on one declared basis.Inputs
Pulp rate and black-liquor solids/lignin
Extraction recovery, wash and product moisture
Heating values, boiler and turbine efficiencies
Dryer, kiln, power value and lignin price
Mechanisms
Dry solids, lignin, inorganic chemical and water balances
Black-liquor heating value after extraction
Steam generation, header demand and turbine power
Kiln fossil displacement and whole-site margin
Constraints
Recovery-boiler solids and energy
Steam-header and power self-sufficiency
Wash water and dryer heat
Product moisture and kiln substitution
Outputs
Lignin tonnes and liquor impact
Recovery load, steam and electricity
Fossil displacement and dryer duty
Margin and extraction-rate Pareto frontier
02 · Acatian workflow
Build it in six controlled steps
Each step creates a reviewable object, not a hidden spreadsheet assumption.- 01
Declare the historical system boundary.
- 02
Close liquor solids and lignin balances.
- 03
Calculate heating-value and recovery impact.
- 04
Add drying, granulation and kiln branches.
- 05
Reconcile steam and power headers.
- 06
Sweep extraction rate and value scenarios.
03 · Decisions
Questions the model should answer
How much lignin can leave the recovery loop?
Sell product or displace kiln fuel?
When does dryer heat dominate?
Which price or energy case reverses the choice?
04 · Evidence boundary
Validate before the result carries weight
Validation
Require dry-solids, water, chemical and energy closure and comparison to authorised mill, boiler, dryer and turbine evidence.
Limitations
Sunila production is historical and ended in 2023. No current Stora Enso operation, proprietary extraction chemistry or actual economics is represented.
Public evidence
What the company context supports—and what it does not.
Sources establish the public process architecture. They do not reveal private operating parameters, site performance or an Acatian relationship.Frequently asked questions
Practical modelling questions
Is this the named organisation's real plant model?
No. It is an independent hypothetical Acatian study based only on the cited public process architecture. It claims no affiliation, endorsement, deployment, confidential data or actual plant performance.
Where do the numerical inputs come from?
Every input must be marked as a public fact, literature estimate, transparent engineering assumption or authorised customer input. The public article does not invent private operating values.
Can the model be calibrated to a real facility?
Yes, when the operator supplies authorised process, equipment, schedule and utility evidence and agrees the intended use, acceptance criteria and validation plan.