This document discusses integrating biomass and black liquor gasification into a kraft pulp mill. It presents several options for producing dimethyl ether (DME) and Fischer-Tropsch diesel while generating power. Additional biomass is gasified to produce syngas for fuels and power generation. Sulfur separation and lime requirements increase for black liquor gasification. Impacts include increased biomass use, elimination of the recovery boiler, and potential increases to power generation and biofuel production. Pyrolysis of biomass is also discussed as an alternative for integrating thermal conversion into pulp mills.

1. Jim Frederick
Table Mountain Consulting, LLC
TMC

2. • Utilize the whole tree
• Produce a variety of forest-derived
products
– Cellulose fiber
– Synthetic fuels and chemicals (e.g.
methanol-to-gasoline, dimethyl
DME, Fischer Tropsch diesel,…)
– Lignin-derived products
– Pharmaceuticals, neutraceuticals
– Electrical power
• Utilize forest materials for energy

3. • Plant economic optimization and market
demand for products determine the optimal
product mix
• Constraint: steam generated must meet mill
steam demands

4. Kraft pulp mill
Methanol
to Gasoline
FT Diesel
DME

5. Gasification
– Biomass => CO, CO2, H2, H2O
– CO + H2 => liquid fuels and
chemicals
Pyrolysis
– Biomass => organic liquids,
gases, char
– Organic liquids are refined
to liquid fuels and chemicals

6. Gasification
– Biomass => CO, CO2, H2,
H2O
– CO + H2 => liquid fuels
and chemicals
Pyrolysis
– Biomass => organic
liquids, gases, char
– Organic liquids are
refined to liquid fuels
and chemicals

7. Choices
– Gasification/pyrolysis feedstock can be biomass OR black
liquor (OR both)
– Products can be power OR both liquid fuels and power
– Fuel products can be chosen independently
– Ratio of fuel products to power is determined through
process design and management of heat utilization
Constraints
– No change in pulp production rate and pulp quality
– Steam production must meet pulp mill requirements

8. Black liquor
concentration
and combustion
Biomass
boiler
Residual biomass
Pulping
operations
Pulp
HP steam
From the EU BLGMF (Altener) report, Dec 2001
Import or export power
Fiber Power and steam

9. Pulp
HP steam
Export power
Liquid fuels
or chemicals
Steam
turbine
Biomass
boiler
Biomass
fuel
Pulping
operations
BL gasification
and liquids
synthesis
plant
From the EU BLGMF (Altener) report, Dec 2001
Pulp

10. 1. Produce dimethyl ether (DME) and power
a. Maximize DME from BLG syngas (DMEa)
i. Recycle unconverted syngas
ii. Burn wood residues and unconverted syngas to
generate process steam and power
b. Increase power production (DMEb)
i. Recycle unconverted syngas
ii. Gasifiy wood residue to fire gas turbine for power
iii. HRSG downstream of gas turbine generates power
and process steam
Based on Larson, Consonni, Katofsky, Iisa, Frederick, A Cost-Benefit Assessment of Gasification-Based Biorefining in the
Kraft Pulp and Paper Industry v. 1-4, report to the USDOE and AF&PA, 2006.

11. 1. Produce dimethyl ether (DME) and power
c. Single pass syngas for increased power (DMEc)
i. Single pass for syngas through DME synthesis reactor
ii. Burn wood residues and more unconverted syngas to
generate process steam and power
iii. HRSG downstream of gas turbine generates power
and process steam

12. 2. Produce Fischer Tropsch diesel and power
a. Maximize DME from BLG syngas (FTa)
i. Syngas from black liquor gasification only
ii. Syngas once-through the FT synthesis reactor
iii. Power island includes a biomass gasifier, syngas
cooler, and combined cycle power plant with process
steam extraction
iv. Unconverted syngas is burned in power island
b. Maximize power generation (FTb)
i. Similar to FTa but with a larger biomass gasifier and
gas turbine for more power generation

13. 2. Produce Fischer Tropsch diesel and power
c. Maximize FT diesel production (FTc)
i. Syngas from both black liquor and biomass gasification
ii. Syngas once-through the FT synthesis reactor
iii. Power island burns only unconverted syngas; otherwise
the same as in FTa and FTb ; combined cycle power plant
with process steam extraction plus a condensing
turbine to utilize excess steam

14. 1. Gasification of both black liquor and
biomass to produce syngas for biofuels
2. Power and steam generation using
combined unconverted syngas plus syngas
from gasified biomass plus heat recovered
from exothermic syngas processing steps

15. Fuel
synthesis
option
Incremental
biomass for fuel
& energy, dry t/d
Net incremental
biomass to mill,
%
Syngas from
biomass goes to:
DMEa 700 5.4% None produced
DMEb 1,326 24% Gas turbine
DMEc 678 4.8% Gas turbine
FTa 829 9.2% Gas turbine
FTb 2,246 51% Gas turbine
FTc 2,704 64% Synthesis
Based on 1725 ADt/d unbl. pulp production and 2458 t/d dry BL solids.

16. 0
20
40
60
80
100
120
140
Steam,kg/s
Liquid fuels processes
Additional steam from
CHP plant
Net steam generated in
fuel plant
Steam generated from
recovery and power
boilers
Pulp mill steam
requirement

17. • Adequate biomass supply
• Separation and recovery of S and Na
– Temperature and pressure effects
– H2S recombined with green liquor => lime required
• Changes in equivalent capacity of some
standard pulp mill operations?
• Configure the integrated plant for excellent
heat utilization

18. • On pulping: none
• On brownstock washing: none
• On black liquor evaporation: none
• On recovery boiler throughput:
 gasification of all black liquor means no demand
for a recovery boiler

19. Sulfur separates from sodium during gasification
(and pyrolysis)
• Recapture of H2S, followed by causticizing:
H2S + Na2CO3 => NaHS + NaHCO3
NaHCO3 + Ca(OH)2
=> NaOH + H2O + CaCO3
• Causticizing of conventional green liquor:
Na2CO3 + Ca(OH)2 => 2NaOH + CaCO3
2 CaO per
2 NaOH
1 CaO per
2 NaOH

20. Lime consumption and causticizer volume
requirement and can be doubled when H2S has
to be recaptured
 55% release at 950oC, pressurized O2 (30 bar)
gasificationa
 15% release at 950oC, atmospheric pressure air
gasificationa
 100% release at 700oC, atmospheric pressure
steam gasification
a Lindblom, M. An Overview of the Chemrec Process Concepts (2003).

21. Oxidant T, C P, bar % of S
to H2S
Increase in lime and
causticizer volume required
O2 950C 30 bar 55% 55%
Air 950C 1 bar 15% 15%
Steam 700C 1 bar 100% 100%

22. Biomass FT crude Power
t/d t/d MWe (net)
a. burn biomass for 1,659 238 88
steam & power, OR
b. gasify biomass for 4,493 238 230
steam & power, OR
c. gasify biomass 5,374 783 78
for syngas
Based on Larson et al., 2006
Gasify black liquor
for syngas AND:
Basis: 1327 ODt pulp/day and 212 MWth process steam produced

23. Impact (as % increase) Gasification
Biomass required to 225%
Evaporation load none
Rcovery boiler throughput -100%
Recaust operations 0% to +100%
Process steam generationa none
Power generation 100% – 170%
Biofuels production, % input LHV 18% - 42%
a steam to pulp mill only

25. • Biomass:
– Much technology development under way
– Commercial pyrolysis technology is available
• Black liquor:
– no technologies under development

26. • Mass distribution (nominal, on an ash-free
basis):
– Pyrolysis gas: 15%
– Pyrolysis oil: 70%
– Pyrolysis char: 15%
• Energy retained in pyrolysis oil: 65-70%
• Integration issues:
– Energy to drive pyrolyze
– Utilization of pyrolysis gas and char

27. Source: K Mäenpää,
Metso, 2012

28. Gases: CO, CO2, H2, H2O(v),
methane, other light
hydrocarbons
Liquids: CxHyOz liquids from
benzene to C20
+
Char: carbon and inorganic matter
60-65% crude oil yield

30. Biomass Crude
pyrolysis oil
Hydrotreated
oil
C, wt-% 51.9 33.7 25.2
H, wt-% 6.2 5.2 4.2
O, wt-% 41.8 31.2
Total 100.0 70.0 29.5
Energy content,
MJ/kg biomass
19.6 17.5
Fuel value retained, % 58.2

32. • To Dr. Kristiina Iisa for her guidance on the
pyrolysis section of this presentation