1. Controlled Pyrolysis of Cotton-gin Trash
Froilan L. Aquino and Sergio Capareda
Biological and Agricultural Engineering
Texas A&M University, College Station, TX.

2. Pyrolysis Process Definition
Pyrolysis – thermal conversion under complete absence of oxidant Typical product yields at different pyrolysis modes.
Mode
Conditions
Liquid
(%)
Char
Gas
Fast
Moderate temperature, around 500C, short hot vapor residence time ~ 1 second 75 12 13
Intermediate
Moderate temperature, moderate hot vapor residence time ~ s 50 20 30
Slow
Low temperature, around 400C, very long residence times 35
Source: EIA, 2007

3. Objectives
To determine the effect of temperature and reaction time on the solid, liquid and gaseous products of CGT;
To evaluate the quality of the solid, liquid and gaseous products by proximate and HHV Analysis;
To identify conditions to maximize the solid (char), liquid and gaseous products from the pyrolysis of CGT; and
To perform a simple energy and mass balance on the biomass after pyrolysis.

4. Methodology
Pyrolysis Tests A) Sample preparation (Drying and Grinding) B) Pyrolysis Runs Temperature: 500, 600, 700, 800C Reaction Time: 30 min Purge Gas Flow rate: 1000 cm3 min-1 Biomass used: 50 g

5. Pyrolysis Set-up
The modified pyrolysis setup used for cotton-gin trash. (A) Purge gas (N2), (B) Gas flow meter 1, (C) Digitally-controlled furnace, (D) tar/moisture trap, (E) Condenser, (F) Thermocouple reader, (G) Liquid collector, (H) moisture trap, (I) Gas flow meter 2, (J) Sampling/exhaust port, and (K) Gas analyzer.
Pyrolyzer/Reactor B C A D E G H I J K F
Hood

6. Results and Discussion
Pyrolysis Products
Solids/Char
Liquid Products
Gaseous Product

7. Results - Char
1. Solid (Char) Analysis:

8. Results - Char Char Analysis (HHV in MJ/kg):
HHV-1 = ave. high heating value of char from preliminary tests.
HHV-2 = ave. high heating value of char from the modified tests.
Note: Both HHV measured at pyrolysis period of 30 min.
Note: CGT has heating value of 15.5 MJ/kg
Temp (ºC)
HHV-1
HHV-2
500 -
19.23
600
16.90
20.33
700
21.96
21.64
800
18.30
19.70

9. Results - Bio-oil 2. Liquid (Bio-oil) Analysis Temperature (°C)
ρave – average density (including water and char)
Temperature (°C)
ρave[a]
(g cm-3)
Average pH HV
(MJ kg­1)
500
0.982
4.7
2.430
600
0.992
5.7
2.336
700
1.015
6.6
2.011
800
1.009
7.6
2.020

10. Results - SynGas
3. Gaseous Product Analysis

11. Results - SynGas Gaseous Product Analysis – Total Hydrocarbon (THC)
500 °C °C °C °C
C1 = methane C4 = butane
C2 = ethane C5 = pentane
C3 = propane C6 = hexane

12. Results - SynGas Pyrolytic gas production from CGT. 500 30.060 1.229
Temperature
(°C)
MWn
(g mol-1)
ρ (kg m-3)
at STP
Mave (g)
VG (m3)
VG (L) GP
(L kg-1)
500
30.060
1.229
17.29
0.0141
14.072
281.27
600
29.682
1.213
14.69
0.0121
12.105
241.82
700
27.908
1.141
19.31
0.0169
16.928
338.52
800
27.033
1.105
19.98
0.0181
18.086
361.59

13. Maximum Conditions Char production: 43 wt.% - 600ºC, 30 min*
2) Liquid Production:
36 wt.% - 800ºC, 30 min
31 wt.% - 600ºC, 30 min

14. Maximum Conditions
3) Gas production: 58 wt.% - 800ºC, 60 min 35 wt.% - 800ºC, 30 min (no loss) 28 wt.% - 800ºC, 30 min (20 % loss)

15. Energy and Mass Balance
Modified Test
The heating values of each pyrolytic product from CGT at different pyrolysis temperatures
Temperature (°C)
HHV (MJ kg-1)
Total HHV
(MJ kg-1)
Gas HHV
(MJ m-3)
Char
Liquid
Gas
500
19.23
2.43
2.74
24.40
3.37
600
20.33
2.34
5.28
27.94
6.41
700
21.64
2.01
6.78
30.43
7.73
800
19.70
2.02
4.26
25.98
4.71

16. Energy and Mass Balance
A. Input
Process/Material
Energy (kJ)
1) Preparation, EG
139
2) Pyrolysis, EP
5184
3) Biomass, EB
774
TOTAL
6097
B. Output
Temperature (°C)
Energy (kJ)
E output
(kJ)
Char
Liquid
Gas
500
367.84
33.27
47.11
448
600
370.60
40.04
77.59
488
700
365.74
27.60
131.43
525
800
300.75
29.84
85.10
416

17. Energy and Mass Balance
Modified Test (mass balance)
Typical mass balance for CGT pyrolysis at different temperatures.

18. Summary and Conclusions
Product yield as affected by pyrolysis temperature and time.
The production of char decreased with increased pyrolysis temperature and time.
The gaseous product yield increased with increased pyrolysis temperature and time.
The bio-oil yield increased at a certain temperature and then leveled off (with slight changes) as the temperature was further increased. Longer pyrolysis period resulted to decreased bio-oil yield.

19. Summary and Conclusions
The highest char yield of almost 40 wt.% was observed at lower pyrolysis temperature and shorter reaction time. The highest liquid yield of approximately wt.% was determined in the lower pyrolysis temperature and shorter reaction time. The highest gaseous product yield of around wt.% was observed at higher pyrolysis temperature and longer reaction time. The Temperature and Time can be Programmed Depending on the Desired Output Product.

20. Summary and Conclusions
Both pyrolysis process resulted to an improved liquid production of up to 36 wt.% which was not determined in previous studies using CGT as feedstock.
The process was considered energy intensive due to the high amount of energy input (6100 kJ) while generating a maximum energy output of only 10%. After disregarding the energy used for preparation and pyrolysis, the energy losses ranged from 30-46% while the energy of the output represent between 55-70% of the input energy from CGT.

21. Acknowledgement Cotton Foundation TAMU Texas AgriLife Research
TAMU Cotton Chair (Dr. Parnell)
Varisco Court Gin Co. Bryan, TX
Jimmy Ropolo, El Campo, TX
Co-majors (Joan Hernandez)
BAEN Student Workers (Ordway, Bert, Jared & Greg)