2015-07-15_ hassan presentation - asabe(dr.kumar reviewed)

Development of Process Model for Assessment of Steam Treatment of Biomass for Pellet Production

S M HASSAN SHAHRUKH, ADETOYESE OYEDUN, AMIT KUMAR

Department of Mechanical Engineering, University of AlbertaEdmonton, AB, Canada

2015 ASABE | ANNUAL INTERNATIONAL MEETINGJuly 26 – 29, 2015, NEW ORLEANS, LA, USA

Presentation Outline Background and Objective Pellet Production Supply Chain Model Development and Validation Mass and Heat balance of Steam

Pretreatment Techno-Economic Result Summary of Result

Presentation at ASABE, 26-29 July, 2015

Background


• Pretreatment helps producing high quality pellets

• Energy density of regular pellets is 1/8th of coal

• High transportation cost of regular biomass and pellets

• Need for higher utilization of Biomass

Low Utilization Cost Issues

Pretreatment

Low Bulk and Energy density of

regular pellets

Objectives

Conduct Techno-Economic Assessment

Cost curves Sensitivity & uncertainty

Conduct Energy Analysis Net energy ratio (NER)

Sensitivity & uncertainty

Develop process model for steam pretreatment of straw and switchgrassHeat and mass

balanceData intensive

modeling


Pellet Supply Chain

Biomass collectio

n

Bale formatio

n/ chipping

Transportation to

pellet plant

Pellet producti

on

Transportation of

pellet to biorefinery

Used in biorefinery

Supply chain of pellet to a biorefinery (Conventional method)

Used in biorefinery

Biomass

collection

Transportation to

pellet plant

Pellet Producti

on

Transportation of

pellet to biorefinery

Steam pretreatm

ent

Bale formation/chip

ping

Steam Pretreatm

ent

Supply chain of pellet (produced from pretreated biomass) to a biorefinery


Experimental Material and Method

Material

Straw and switchgrass

Moisture content ~ 10%-14%

Method

Pretreatment carried in 2.6L StakeTech

Steam gun with 400g of biomass treated at different temperature

and time

Steam treated biomass pelletized


Model Input and Validation

1. Boiler unit: Supply of steam at different time and

temperature

2. Steam Pretreatment Unit: Biomass

is treated with high pressure steam in batch

reactor (Yield reactor considered)

logR = logනexp(T− 10014.75 )dt Governing Equation:

Source: Lam et al. 2013


Key Improvement: Improves the calorific value by increasing the Carbon content and reducing

oxygen content.

Model Input and Validation

3. Pellet mill: produces pellet of

20-30 mm long, 6 mm in diameter, has a heating element

operating at 70-100 C.

2. Grinder: Kicks energy constant 100KJ/kg, solid recovery 95%

1. Dryer: operating temperature at

80 C.

Presentation at ASABE, 26-29 July,2015

No grinder is required for pellet production of straw and switchgrass

Model Validation Result

Operation

Experimental Energy Consumption (kJ)

ASPEN model Predicted Energy Consumption (kJ)

Straw Switchgrass Straw Switchgrass

Steam Pretreatment 749 678 760 710

Drying 6731 8979 6951 9045

Size reduction 0 0 0 0

Pelletization 330 318 352 325


Comparative Heat and Mass balance


Dryer Hammer Mill

Pellet Mill

1kg

0.95 kg

0.92kg

0.85 kg

17 MJ

0 MJ

0.3MJ

0.8 MJ

Dryer Hammer Mill

Pellet Mill

1kg

0.95 kg

0.92kg

0.88 kg

17 MJ

0 MJ

0.3MJ

0.8 MJ

Straw Switchgrass

A. Regular Pellet A. Regular Pellet

B. Steam Pretreated Pellet B. Steam Pretreated Pellet

Dryer Hammer

Mill Pellet Mill

3.0 kg

0.8 kg

0.8kg

0.72 kg

19 MJ

1kg

0.8MJ

6.7 MJ

0 MJ

0.42 MJ

Dryer Hammer

Mill Pellet Mill

3.4 kg

0.8 kg

0.8kg

0.71 kg

19.1 MJ

1kg

0.7MJ

8.9 MJ

0 MJ

0.4 MJ

Variation of NER with Pretreatment Temperature and Level


0

0.5

1

1.5

2

2.5

3

140 160 180

NER

Steam Pretreatment Temperature

Straw Switchgrass

0

1

2

3

4

5

6

7

25% 50% 75%

NER

Pretreatment level

Straw Switchgrass

Process NER falls with increase of pretreatment level and temperature

Uncertainty Analysis


Straw SwitchgrassStraw NER at 95% confidence interval is 1.62±.0.10

Switchgrass NER at 95% confidence interval is 1.42±0.11

Techno-Economic Snapshot


Straw Forest residue SwitchgrassRegular Steam

pretreatedRegular Steam

pretreatedRegular Steam

pretreatedOptimum size (t year-1)

190,000 250,000 190,000 290,000 190,000 230,000

Pellet cost ($ t-1) 122.04 188.34 116.01 183.14 116.20 192.41-Capital recovery 9.56 15.31 10.83 20.34 13.74 21.53- Maintenance cost 2.64 3.68 2.34 3.59 2.58 3.76-Field cost 52.34 58.75 28.19 32.08 25.57 29.39-Transportation cost 33.89 42.99 37.04 50.24 45.38 57.68-Premium 0.00 0.00 6.39 5.50 5.34 6.13-Employee cost 7.27 7.85 6.58 6.76 7.27 8.53-Energy cost 5.41 48.91 14.74 53.79 5.41 54.50-Consumable item cost

10.93 10.86 9.90 10.84 10.93 10.88

Pellet transportation 6.30 5.50 6.20 5.45 6.80 6.10Total pellet delivery cost

128.34 193.84 122.21 188.59 123.00 198.51

Variation of Transportation cost


Variation of Capital Cost


Variation in Production Cost


Process scalability depends on maximum unit size available and optimization between transportation and capital cost

Sensitivity Analysis- Straw


-20.00% -10.00% 0.00% 10.00% 20.00%180.00

185.00

190.00

195.00

200.00

205.00

capital cost employee costEnergy cost Transportation cost

% change

Tota

l cos

t of p

elle

t ($(

t)-1

)

-20.00% -10.00% 0.00% 10.00% 20.00%188.00

190.00

192.00

194.00

196.00

198.00

200.00

Moisture contentFeed stock material loss Inflation

% change

Techno-Economic model is sensitive to transportation, moisture content and IRR parameter

Sensitivity Analysis - Switchgrass


-20.00% -10.00% 0.00% 10.00% 20.00%186.00

191.00

196.00

201.00

206.00

capital cost employee costEnergy cost Transportation cost

% change

Tota

l cos

t of p

elle

t ($(

t)-1)

-20.00% -10.00% 0.00% 10.00% 20.00%193.00

194.00

195.00

196.00

197.00

198.00

199.00

200.00

201.00

202.00

203.00

Moisture content Feed stock material loss Inflation IRR% area

% change

Techno-Economic model is sensitive to transportation, moisture content and material loss parameter

Uncertainty Analysis


0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

0.055

Pro

bab

ility

230 235 240 245 250 255 260 265 270 275Pellet Cost ($/tonne)

5% 90% 5%

5%(x = 236.39) 95%(x = 261.8)

Straw

0.00

0.01

0.02

0.03

0.04

0.05

0.06

Pro

bab

ility

230 235 240 245 250 255 260 265 270 275Pellet Cost ($/tonne)

5% 90.005% 4.995%

5%(x = 237.93) 95.005%(x = 258.65)

SwitchgrassStraw and Switchgrass Production cost at 95% confidence interval is

$ 233-260 with standard deviation of $10

Summary of Result

Energy

• Energy ratio of regular pelletization process is higher than steam pretreated pellet due to addition of steam as energy source

• Calorific value of pellet increases by 21% due to steam pretreatment

• Grinding energy input is zero for straw and switchgrass

Cost

• $/tonne cost of production for steam pretreated pellet is higher than regular pellet due to increased capital cost

• $/GJ cost production of pellet for both steam treated pellet and regular pellet is similar with approximately 30 cents difference

Scaling

• Steam pretreatment is more effective over a plant size of 270,000 tonnes/yr plant capacity due to economy of scale benefits based on $/GJ


AcknowledgementBio Fuel Net

University of Alberta

Dr. Shahab Sokhansanj, Dr. Linoj Kumar and Bahman Ghiasi, Department of Chemical Engineering, University of British Columbia

Presentation at BFN 22-24 July,2015

THANKS

Contact Information:

Dr. AMIT KUMAR

Professor

NSERC/Cenovus/Alberta Innovates Associate Industrial Research Chair in Energy and

Environmental Systems Engineering

Cenovus Energy Endowed Chair in Environmental Engineering

Department of Mechanical Engineering, University of Alberta

[email protected]

www.energysystems.ualberta.ca

+1 780 492 77972015 CSBE | SCGAB Annual General Conference

July 5 – 8, 2015, Edmonton, AB, Canada

mailto:[email protected]

http://www.energysystems.ualberta.ca/

2015-07-15_ hassan presentation - asabe(dr.kumar reviewed)

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