simulation of methanol synthesis from syngas obtained...

Simulation of methanol synthesis from syngas obtained through biomass

gasification using Aspen Plus®

M. Puig-Gamero, J. Argudo-Santamaria, J. L. Valverde, P. Sanchez, and L. Sanchez-Silva

6th International Conference on Sustainable Solid Waste Management

(NAXOS 2018)

Naxos Island, 15th June 2018

Department of Chemical Engineering, University of Castilla-La Mancha, Spain

*[email protected]

1

1. Introduction

2. Aspen Plus modelling

2.1. Gasification process

2.2. Syngas cleaning: Pressure swing adsorption (PSA)

2.2. Methanol synthesis process

3. Results

3.1. Gasification simulation model

3.2. Methanol synthesis simulation

3.3. Gas emission

3.4. Optimal process improvement

Simulation of methanol synthesis from syngas obtained through biomass gasification using Aspen Plus®

2

TABLE OF CONTENTS

1. Introduction





3. Results



3.3. Gas emission



3

TABLE OF CONTENTS

Renewable Energies

Problems derived from their use

Fossil fuelsEnergy demand

Disadvantages Advantages

4

Simulation of methanol synthesis from syngas

obtained through biomass gasification using Aspen Plus®

TABLE OF CONTENTS

1. Introduction

2. Aspen plus modelling


2.2. Syngas cleaning: Pressure

swing adsorption (PSA)


3. Results



3.3. Gas emission

3.4.Optimal process improvement

BIOMASS

“All organic material including trees, crops, algae and residues which are susceptible to be converted into energy”

Types of biomass

Pine bark

5

Second-generation biomass

First-generation biomass

Third-generation biomass

Fourth-generation biomass



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Uses of syngas

• Methanation

• Fischer-Tropsch

• Methanol synthesis

• Intermedies (Toluene, isobutane)

Energy conversion of biomass

Thermochemical process

Biochemical process

• Pyrolysis

• Combustion

• Gasification

• Licuefaction

• Alcoholic fermentation

• Anaerobic digestion

6

Syngas



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


7

Gasification can be defined as the conversion of biomass into a gaseous fuelby heating in a partial oxidation atmosphere



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Biomass Gasifying agent(steam)

Syngas(CO, H2, CO2, CH4)

Water Gas: ⇌

Water gas shift: ⇋

Steam reforming: ⇌ 3

Boudouard: ⇌ 2

Tar forming: 6 9 ⇌ 6

Reactions involved in gasification process:

8



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Methanol synthesis

2 ⇌

3 ⇌

Low conversion

Catalys: Cu/ZnO

Reactions

2,1

2,4 2,5

0,13 0,14

Syngas composition:

Syngas

• CO

• H2

• CO2

• CH4

• Traces

Feedstock

9



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


• Blocks

• Streams

• Design specifications, codes

Aspen Plus®

Simulation process

Pilot plant

Pilot plant

SPEED

PRICEThe main objetive of this research was the simulationof three integrated process: pine gasification, syngascleaning and metanol synthesis using Aspen Plus®

1. Introduction





3. Results



3.3. Gas emission



10

TABLE OF CONTENTS

11



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Syngas purification

R-1SEP-2

R-3

MIXER-1R-2

PSA1

SEP-3

PSA2V-1

PSA3

PSA4

MIXER-3

SPLIT-1

C-2

C-3

MIXER-2

SPLIT-2

COOLER-1

MIXER-4

R-5

SEP-1

R-4

V-2

V-3

V-4

V-5

SEP-4C-1

C-4

R-6HEATX-1

HEATX-2

V-6METSEP

1

11

10

4 16

22

25

18

17

24

27

26

29

30

34

36

4541

42

47

23

4039

33

32

50

38

2

7

3

5

12 15

28

3137

35

19 21

20

46

48

9

86

14 13

Q-1

Q-2

Q-3

49

52

53

Gasification process

Methanol synthesis

Aspen Plus® flowsheet process

1. Introduction





3. Results



3.3. Gas emission



12

TABLE OF CONTENTS

13



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission



R-1SEP-2

R-3

MIXER-1R-2 SEP-3

R-5

SEP-1

R-4

HEATX-1

HEATX-2

1

11

10

4 16 18

17

2

7

3

5

12 15

9

86

14 13

Q-1

Q-2

Q-3

Thermodynamic equilibrium model (reaction kinetics are unknown)

14



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


R-1SEP-2

R-3

MIXER-1R-2 SEP-3

R-5

SEP-1

R-4

HEATX-1

HEATX-2

1

11

10

4 16 18

17

2

7

3

5

12 15

9

86

14 13

Q-1

Q-2

Q-3

R-1 (RYIELD): Biomass pyrolysis reactor, it decomposedthe biomass into its compounds and ash.

R-2 (RGIBBS): It models chemical equilibriumminimizing the Gibss free energy. It was used to produceCO2, CO, CH4, H2S and NH3.

SEP-1: Separator of the amount of char necessary toachieve the gasification temperature.


15



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission



R-1SEP-2

R-3

MIXER-1R-2 SEP-3

R-5

SEP-1

R-4

HEATX-1

HEATX-2

1

11

10

4 16 18

17

2

7

3

5

12 15

9

86

14 13

Q-1

Q-2

Q-3

R-5

Heatx-1

R-5 (RSTOIC): Char combustion reactor.

Heatx-1: Exchange heat between the outlet stream from R-5 and theair inlet stream.

Design specifications:1. Amount of char for combustion

2. Air flow

16



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


R-1SEP-2

R-3

MIXER-1R-2 SEP-3

R-5

SEP-1

R-4

HEATX-1

HEATX-2

1

11

10

4 16 18

17

2

7

3

5

12 15

9

86

14 13

Q-1

Q-2

Q-3

R-3 R-4

Heatx-2

R-3 (RGIBBS): It simulated the gasifier.

R-4 (RSTOIC): It was used to model the tarreforming using Dolomite as a catalyst.

Heatx-2: Heater to warm up the gasifyingagent (water steam).


17



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


R-1SEP-2

R-3

MIXER-1R-2 SEP-3

R-5

SEP-1

R-4

HEATX-1

HEATX-2

1

11

10

4 16 18

17

2

7

3

5

12 15

9

86

14 13

Q-1

Q-2

Q-3

The main blocks of gasification process were integratedenergy through Q-1, Q-2 and Q-3.

Energy requirements = 0


1. Introduction





3. Results



3.3. Gas emission



18

TABLE OF CONTENTS

19



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


PSA1

SEP-3

PSA2V-1

PSA3

PSA4

MIXER-3

SPLIT-1

C-2

C-3

MIXER-2

SPLIT-2 MIXER-4

V-2

V-3

V-4

V-5

SEP-4C-1

C-4

22

25

18

17

24

27

26

29

34

36

4541

42

23

4039

33

3238

28

3137

35

19 21

20

Syngas cleaning: Pressure swing adsorption (PSA)

2,1 2,4 2,5 0,13 0,14

Specifications:

Temperature and pressure of adsorbers: 35 ºC and 30 atm

PSA1

SEP-3

PSA2V-1

PSA3

PSA4

MIXER-3

SPLIT-1

C-2

C-3

MIXER-2

SPLIT-2 MIXER-4

V-2

V-3

V-4

V-5

SEP-4C-1

C-4

22

25

18

17

24

27

26

29

34

36

4541

42

23

4039

33

3238

28

3137

35

19 21

20

PSA1

Water

PSA2

MIXER-2

SPLIT-1

H2

CO

20



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


PSA1 separates the H2

PSA2 separates the CO

MIXER-2 mix the H2 and CO

SPLIT-1 separates the CO to achieve the H2/CO ratio

SEP-3 separates the char

SEP-4 separates the watercondensed


21



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


PSA1

SEP-3

PSA2V-1

PSA3

PSA4

MIXER-3

SPLIT-1

C-2

C-3

MIXER-2

SPLIT-2 MIXER-4

V-2

V-3

V-4

V-5

SEP-4C-1

C-4

22

25

18

17

24

27

26

29

34

36

4541

42

23

4039

33

3238

28

3137

35

19 21

20

PSA3

PSA4

SPLIT-2

CO2

CH4

PSA3 separates the CO2

PSA4 separates the CH4


1. Introduction





3. Results



3.3. Gas emission



22

TABLE OF CONTENTS

MIXER-3

COOLER-1C-4

R-6

V-6METSEP45

47 50

46

49

53

23



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


R-6 simulates the metanol synthesis

2 ⇌ 3 ⇌

Catalyst: Cu/ZnO

METSEP separates the crude methanol, gas-phase and impurities

METHANOL

Methanol synthesis process

1. Introduction





3. Results



3.3. Gas emission



24

TABLE OF CONTENTS

25



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Model validation

Compound Experimental composition * (vol.% db)

Predicted composition(vol.% db)

H2 45-55 57

CO 21-25 20

CO2 18-22 18

CH4 2-4 2,2

*(British Columbia University)

Condicions: Temperature: 831ºC

Pressure: 1 atm

Biomass:

Wood pellets

Error: 5-7 %

26



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Effect of the S/B mass ratio on the syngas composition

0.5 0.6 0.7 0.8 0.9 1.00

20

40

60

80 800 ºC 900 ºC 1000 ºC

H2 (v

ol.%

dry

bas

is)

S/B (ratio)

0.5 0.6 0.7 0.8 0.9 1.0

0

20

40

60

80

800 ºC 900 ºC 1000 ºC

CO

2 (vol

.% d

ry b

asis

)

S/B (ratio)

0.5 0.6 0.7 0.8 0.9 1.0

0

10

20

30

40

50

60

70

80 800 ºC 900 ºC 1000 ºC

CH

4 (vol

.% d

ry b

asis

)

S/B (ratio)

a)

c) d)

b)

0.5 0.6 0.7 0.8 0.9 1.00

20

40

60

80

800 ºC 900 ºC 1000 ºC

CO

(vol

.% d

ry b

asis

)

S/B (ratio)

S/B mass ratio S/B mass ratio


H2 CO

CO2 CH4

27



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission



0.5 0.6 0.7 0.8 0.9 1.00

20

40

60

80 800 ºC 900 ºC 1000 ºC

H2 (v

ol.%

dry

bas

is)

S/B (ratio)

0.5 0.6 0.7 0.8 0.9 1.0

0

20

40

60

80

800 ºC 900 ºC 1000 ºC

CO

2 (vol

.% d

ry b

asis

)

S/B (ratio)

0.5 0.6 0.7 0.8 0.9 1.0

0

10

20

30

40

50

60

70

80 800 ºC 900 ºC 1000 ºC

CH

4 (vol

.% d

ry b

asis

)

S/B (ratio)

a)

c) d)

b)

0.5 0.6 0.7 0.8 0.9 1.00

20

40

60

80

800 ºC 900 ºC 1000 ºC

CO

(vol

.% d

ry b

asis

)

S/B (ratio)



H2 CO

CO2 CH4

H2 y CO2

CO y CH4

Water Gas: ⇌



Boudouard: ⇌ 2


28



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission



0.6 0.8 1.01.5

2.0

2.5

3.0

3.5 800 ºC 900 ºC 1000 ºC

H2/C

O m

ole

ratio

S/B mass ratio

0,9

H2/CO = 2,4

e)

0.5 0.6 0.7 0.8 0.9 1.00

20

40

60

80 800 ºC 900 ºC 1000 ºC

C6H

6 (vol

.% d

ry b

asis

)

S/B (ratio)

S/B mass ratio

C6H6

6 9 ⇌ 6

0.5 0.6 0.7 0.8 0.9 1.00

10

20

30

40

50 800 ºC 900 ºC 1000 ºC

CH

3OH

(kg/

h)

S/B mass ratio

CH3OH

S/B = 0,9



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Effect of gasification temperature

800 900 10000

20

40

60

80 H2

CO CO2

CH4

C6H6

CH

3OH

yie

ld (k

g/h)

Gas

com

posi

tion

(vol

.% d

ry b

asis

)

Temperature (ºC)

0

10

20

30

40

50

CH3OH

H2, CO and CH3OH

CO2, CH4 and C6H6

0.6 0.8 1.01.5

2.0

2.5

3.0

3.5 800 ºC 900 ºC 1000 ºC

H2/C

O m

ole

ratio

S/B mass ratio

29



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Effect of gasification temperature

H2, CO and CH3OH

CO2, CH4 and C6H6

Water Gas: ⇌


Boudouard: ⇌ 2



Temperature = 900ºC

Endothermics

Exothermics

30

1. Introduction





3. Results



3.3. Gas emission



31

TABLE OF CONTENTS



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Methanol synthesis: validation

Stoichiometricreactor

Equilibriumreactor

% Error

CH3OH (kg/h) 16.5 15.4 7.1

40 50 60 70 800

10

20

30

40

50 220 ºC 240 ºC 260 ºC

CH

3OH

pro

duct

ion

(kg/

h)

Pressure (atm)

Pressure and temperature influence on metanol production

Working at high pressures:

• Operational risks

• High costs

• Human danger

Industrial plants 55 atm

CH3OH Pressure

33



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


P= 55 atm

9 kg/h

Optimal conditions for metanol synthesis : 55 atm

220 ºC

- At high temperatures, the catalyst can be damaged.

- At low temperatures can reduce the reaction rate

Pressure and temperatura influence on metanol production

CH3OH Temperature32 kg/h

34

1. Introduction





3. Results



3.3. Gas emission



34

TABLE OF CONTENTS



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Capture and gas emissions

Emis

ión

de g

ases

(K

g/h)

Capture:

80% CO2

95% CH4

CO2 produced from thecombustión chamber

Low NH3 and H2S emission

36

1. Introduction





3. Results



3.3. Gas emission



36

TABLE OF CONTENTS



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Optimal process improvement

Cau

dal m

ásic

o (K

g/h)

Cau

dal m

ásic

o (K

g/h)

Char to combustion chamber: 40% 10%.

C available CO methanol.

CO CO2 CO2capture

Combustion chamber:H2 reacted with O2 to produce H2O and decrease CO2 formation.

NH3 and H2S were kept

38



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Final simulation

Syngas cleaning

R-1SEP-2

R-3

MIXER-1R-2

PSA1

SEP-3

PSA2V-1

PSA3

PSA4

MIXER-3

SPLIT-1

C-2

C-3

MIXER-2

SPLIT-2

COOLER-1

MIXER-4

R-5

SEP-1

R-4

V-2

V-3

V-4

V-5

SEP-4C-1

C-4

R-6HEATX-1

HEATX-2

V-6METSEP

1

11

10

4 16

22

25

18

17

24

27

26

29

30

34

36

4541

42

47

23

4039

33

32

50

38

2

7

3

5

12 15

28

3137

35

19 21

20

46

48

9

86

14 13

Q-1

Q-2

Q-3

49

52

53


Methanol synthesis

T = 220ºCP = 55 atm

T = 900ºCS/B mass ratio = 0.9

Recycle

39



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emmission


Spanish Ministry of Education, Culture and Sports for FPU grant

Acknowledgement

39

Authors acknowledge the financial support from the Spanish Ministry of Education, Culture and Sports for FPU grant (FPU15/02653).

Thanks you very much for your attention!

Simulation of methanol synthesis from syngas obtained through biomass

gasification using Aspen Plus®M. Puig-Gamero, J. Argudo-Santamaria, J. L. Valverde, P. Sánchez, and L. Sanchez-Silva

6th International Conference on Sustainable Solid Waste Management

(NAXOS 2018)

Naxos Island, 15th June 2018

Department of Chemical Engineering, University of Castilla-La Mancha, Spain

*[email protected]

40

41

grant

Conclusions

- The gasification process was simulated using a thermodynamic equilibrium model which is based on the minimization of the

Gibbs free energy of the system. A double chamber gasifier, which allows the separation of the gasification and combustion

zones to obtain a high-quality gas, was considered. The influence of the steam to biomass (S/B) mass ratio and the temperature

on the gas product composition and methanol production was studied. The best calculated operational condition of the process

was 900ºC and a S/B mass ratio of 0.9.

- One of the main technical barriers for the syngas production is the presence of tar coming from the gasification process.

According to the simulation performed, tar production was hindered with increasing temperatures and steam flow rates.

Dolomite was used as the catalyst in the decomposition of tar due to its low cost.

- A pressure swing adsorption (PSA) process was considered to clean the syngas and simultaneously capture the greenhouse

gases. Therefore, about 80% of the CO2 and 95% of the CH4 were sequestered.

- Once the H2/CO molar ratio of the clean syngas was fitted, the methanol synthesis proceeded. Although the methanol production

is favoured at high pressures and low temperatures, a pressure of 55 atm was selected to avoid operational issues. Thus, 220ºC

and 55 atm were selected as the optimal operation conditions for the methanol synthesis.

- Finally, to improve the process yield, the methanol synthesis waste stream is recycled to the combustion chamber. With this

recycle, the carbon required to burn is reduced from 40 to 10%. Thus, there is a higher amount of carbon available to be used in

the gasification process. 42

42

Mineral content determination:

Proximate analysis:

Ultimate analysis:

Thermogravimetric analysis:

Mass spectrometric analysis:

Thermogravimetric analyzer TGA-DSC 1 (METTLER Toledo)

Mass spectrometer Thermostar-GSD 320/quadrupole mass analyzer(PFEIFFER VACUUM)

Inductively coupled plasma (ICP) (Liberty Sequential. Varian)

Standard Procedure Volatile matter (VM): UNE-EN 15148Ash content (AC): UNE-EN 14775Moisture content (MC): UNE-EN 14774

Fixed Carbon*dab = 100 – (VM+AC+MC)*dab

CHNS/O analyzer (LECO CHNS-932)O*dab= 100-(C+H+N+S)*dab

RE

AC

TIN

G A

ND

G

AS

AN

ALY

SIS

UN

ITS

CH

AR

AC

CT

ER

IZAT

ION



TABLE OF CONTENTS

1. Introduction






3. Results



3.3. Gas emission


Tar craking

TarC3H8, C6H6, C7H8, C8H8, C4H10, C6H12

Operating issues due to tar condensation

Primary process: Optimization of gasifier and operating conditions

Secondary process: Catalytic process. DOLOMITE

S/B= 0.6T = 800 ºC

→ 2 6 → 3 12

3 → 2

Removal

31

simulation of methanol synthesis from syngas obtained...

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