Pyrolysis of SwitchgrassAmanda Drabek & Kang-Lih Chey

IntroductionBio-Oil Components:

Bio-Oil

Switchgrass

Goals of this Project

Design pyrolysis process to convert switchgrass to bio-oil and upgrade to liquid fuel.

Determine factors that would make process economical.

Upgrading Options

1. Upgrade bio-oil using hydrotreating process

2. Upgrade bio-oil using catalytic deoxygenation

› Consider 5 different scenarios.

Design Pyrolysis Process

Lab Scale Pyrolysis Reactor System

“Bench-Scale Fluidized-Bed Pyrolysis of Switchgrass for Bio-Oil Production.” Boateng, et. al. Ind. Eng. Chem. Res. 2007.

Industrial Scale Pyrolysis ProcessUnits = Metric Tons/hr

Switchgrass 100

Energy Required for the Pyrolysis Process: 81,812 MJ

Energy Supplied by Char: 252,000 MJ

Selecting Reactor Type

Use fluid bed reactor.

Optimum Reactor Temperature

Reactor Temperature is 480 °C

http://www.unh.edu/p2/biooil/bounhif.pdf

Plant Location

Build the plant in Iowa› Centrally located in Midwest› Research currently being done in Iowa

regarding switchgrass

20 acres of land for biofuels plant› Cost of land in Iowa is $5140 per acre› Total cost of land for the plant is $102,800

Transportation Costs

Transportation is $0.10 per ton switchgrass per mile

Plant based on 100 tons/hr switchgrass feed Transportation cost is $860 per hr

Distance Distribution

0%

10%

20%

30%

Miles 20 40 60 80 100 120 140 160 180

Distance from Biofuels Plant

% o

f Far

ms

Upgrading Option 1: Hydrotreating

Hydrotreating Overview

Reacts hydrogen with bio-oil to remove oxygen.

Hydrogen is produced from steam reformer.

Steam reformer uses NCG and additional methane as feed.

Hydrotreating Economic Summary

TCI = $41.5 million

Manufacturing Cost = $157.7 million/yr

Net Profit first year = -$13.73 million

ROI = -0.33

Equipment Cost (in millions)Pyrolysis unit $1.20Hydrotreater $5.00Steam Reformer $0.69Land (acres) $0.10Total Equipment Costs $6.99

Direct CostsPurchased equipment $6.99Purchased-equipment installation $3.29Instrumentation and controls $2.52Piping $4.76Electrical systems $0.77Buildings $1.26Yard improvements $0.70Service facilities $4.89Total Direct Costs $25.17

Indirect CostsEngineering and supervision $2.31Construction expenses $2.87Legal expenses $0.28Contractor's fee $1.54Contingency $3.08Total Indirect Costs $10.07

Fixed Capital Investment $35.24Working Capital $6.22Total Capital Investment $41.47

Break Even Points Analysis

Break even Oil Price: $119/bbl

Break even Feed Rate: 165 ton/hr

0 50 100 150 200 250 300 350

-1.5-1

-0.50

0.51

1.52

2.53

3.5

Hydrotreating Option-ROI v. Oil Price

Oil Price ($/bbl)

ROI

0 100 200 300 400 500 600

-1-0.5

00.5

11.5

22.5

33.5

Hydrotreating Option-ROI v. Feed Rate

Feed Rate (tons switchgrass/h)

ROI

Hydrotreating: Optimized Process

Raise product price to $119/bbl Increase scale to 500 tons/hr feed

Optimized Net Profit: $200 million Optimized ROI: 4.8

Conclusion: Not significant ROI

Conclusion from Hydrotreating Method

Not likely to be profitable.› Need to operate at a large scale because

of high capital investment.

› No significant factor that can be manipulated.

› Efficiency of process is not likely to be improved.

Upgrading Option 2: Catalytic Deoxygenation

Catalyst Chosen: HZSM-5 Zeolite

Produces mostly aromatic products. Produces an organic and aqueous layer

which is easily separable. Stable at high temperatures.

Octane Numbers of Upgraded OilChemical % wt. fraction Octane #

Benzene 1.2 101Toluene 3.1 114Ethylbenzene 2.6 115.51,3-dimethylbenzene 9.4 145Propylbenzene 0.2 1271,2,4-trimethylbenzene 11.8 136Butylbenzene 0.3 97.52-methylphenol 3.3 ---1-Methyl-4-benzene 2.4 ---1,2,3,5-tetramethylbenzene 0.5 100Naphthalene 6.2 Not a component in

today’s liquid fuel.Methylnaphthalene 9.2

1-ethylnaphthalene 3.4

2,3-dimethylnaphthalene 6.3

Methylanthracene 2.6

Dimethylanthracene 0.5

Components found in today’s fuel.

High octane numbers.

Components NOT found in today’s fuel.

Niche market for Naphthalene.

Boiling Points of Upgraded OilChemical % wt. fraction Boiling Point (oF)

Benzene 1.2 176.18Toluene 3.1 231.1Ethylbenzene 2.6 277.11,3-dimethylbenzene 9.4 358Propylbenzene 0.2 318.61,2,4-trimethylbenzene 11.8 336.9Butylbenzene 0.3 361.92-methylphenol 3.3 359.31-Methyl-4-benzene 2.4 3941,2,3,5-tetramethylbenzene 0.5 388.4Naphthalene 6.2 424.3

Methylnaphthalene 9.2 472.3

1-ethylnaphthalene 3.4 496.9

2,3-dimethylnaphthalene 6.3 511.3

Methylanthracene 2.6 646.1

Dimethylanthracene 0.5 Expected to be above the methylantracene.

Can separate components based on boiling points.

Can remove Benzene and Toluene if desired.

Catalytic Deoxygenation ProcessUnits = Metric Tons/hr

Total Energy Produced – Total Energy Required = Energy

Remaining

252000 – 42000 = 210000 MJ

Catalytic Deoxygenation Economics

TCI = $22.91 million

Manufacturing Cost = $121 million/yr

Net Profit first year = -$3.24 million

ROI = -0.15

Equipment Costs (in millions)Pyrolysis unit $1.20Cat Reactor $0.67regenerator $1.63storage tank $0.04separator $0.07land (acres) $0.10Total Equipment Cost $3.72

Direct CostsPurchased equipment $3.72

Purchased-equipment installation $1.75Instrumentation and controls $1.34Piping $2.53Electrical systems $0.41Buildings $0.67Yard improvements $0.37Service facilities $2.60Total Direct Costs $13.39

Indirect CostsEngineering and supervision $1.23Construction expenses $1.52Legal expenses $0.15Contractor's fee $0.82Contingency $1.64Total Indirect Costs $5.36

Fixed Capital Investment $18.75Working Capital $3.31Total Capital Investment $22.06

Break Even Points Analysis

Break even Oil Price: $110/bbl

Break even Feed Rate: 66 tons/hr

0 100 200 300 400 500 600-2-1012345678

Catalyst Option-ROI vs. Feed Rate

Feed Rate (tons switchgrass/h)

ROI

0 50 100 150 200 250 300 350

-1.5-1

-0.50

0.51

1.52

2.53

Catalyst Option-ROI vs. Oil Price

Oil Price ($/bbl)

ROI

Upgrade Bio-Oil using Cat. Deox.

Break even Catalyst Price: $996/ton Current Price: $1320/ton We believe that the catalyst price will

decrease when produced in bulk.

0 200 400 600 800 1000 1200 1400 1600

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

Catalyst Option-ROI vs. Cata-lyst Price

Catalyst Price ($/ton)

ROI

Alternate Scenarios

Scenario 0: original scenario Scenario 1: Decrease amount of catalyst used

from 17 g cat/g oil/min to 8.5 g cat/g oil/min Scenario 2: Regenerate catalyst 10 times

instead of 2; run on 30 minute cycles instead of hour cycles.

Scenario 3: Increase Yield of Product Oil to 23 wt %.

Scenario 4: Process is separate from refinery; add separation process and transportation costs

Comparing Alternate Scenarios:Oil Price

Want to sell oil for cheapest price.

Scenarios 1 and 2 are best.

0 1 2 3 40

50

100

150

200

250

300

350

Breakeven Oil Price for Different Scenarios

Scenario

Oil

Pri

ce (

$/b

bl)

Comparing Alternate Scenarios:Plant Size

Plant size is similar across all scenarios except 4.

0 1 2 3 40

10

20

30

40

50

60

70

80

Breakeven Plant Size for Different Scenarios

Scenario

Pla

nt

Siz

e (t

on

s/h

r)

Comparing Alternate Scenarios:Catalyst Price

Want to breakeven with highest catalyst price.

Scenario 2 is best.

0 1 2 3 40

500

1000

1500

2000

2500

3000

3500

4000

Breakeven Catalyst Price for Different Scenarios

Scenario

Cat

alys

t P

rice

($/

ton

)

Catalytic Deoxygenation: Optimized Process

Use Scenario 1 as basis Increase oil price to $110/bbl Increase scale to 500 ton/hr

Optimized Net Profit: $170 million Optimized ROI: 7.8 Conclusion: Significant ROI

Conclusions from Scenarios

Scenarios 1 & 2 are most economical.› Scenario 1: Use less catalyst.› Scenario 2: Use catalyst for more cycles.

Optimized scenario gives reasonable ROI

Should combine process with refinery. Want to increase selectivity of catalyst.

Components of Upgraded Bio-OilChemical % wt. fraction Octane #

Benzene 1.2 101Toluene 3.1 114Ethylbenzene 2.6 115.51,3-dimethylbenzene 9.4 145Propylbenzene 0.2 1271,2,4-trimethylbenzene 11.8 136Butylbenzene 0.3 97.52-methylphenol 3.3 ---1-Methyl-4-benzene 2.4 ---1,2,3,5-tetramethylbenzene 0.5 100Naphthalene 6.2 Not a component in

today’s liquid fuel.Methylnaphthalene 9.2

1-ethylnaphthalene 3.4

2,3-dimethylnaphthalene 6.3

Methylanthracene 2.6

Dimethylanthracene 0.5

Want to increase selectivity for blue and purple components because they are found in today’s fuel.

Proposed Experiments

Determine how many times can you regenerate the catalyst for a set run time.

Determine minimum amount of catalyst that can give a desirable product.

Increase selectivity of catalyst for liquid product.

Conclusions Pursue Catalytic Deoxygenation

method For catalyst:

› Decrease amount used› Increase selectivityScenario TCI

(million $)Net Profit (million $)

ROI

Hydrotreating $41.5 -$13.73 -0.33

Cat. Deox. Original

$22.06 -$3.24 -0.15

Cat. Deox. 1 $22.06 $10.09 0.46

Cat. Deox. 2 $22.06 $8.24 0.37

Cat. Deox. 3 $22.06 $10.07 0.46

Cat. Deox. 4 $22.06 -$24.32 -1.06

Questions?

Reactor Types

Fluidized BedCirculating Fluidized Bed Ablative