This document summarizes a student seminar on co-gasification of rice straw and LDPE plastic. The objectives were to study how adding polymer affects the gasification process and products. Students presented on biomass gasification reactions, their experimental setup and procedure, preliminary results on tar and char weights with different amounts of LDPE added, and issues faced like reactor leaks. The seminar was led by three students for their project guide to report on their study of co-gasifying rice straw and plastic waste.

1. Project Phase 1 Seminar
BT19CME045 Prabuddha Gope
BT19CME051 Himanshu Yadav
BT19CME085 Kartik Prasad
Project Guide: Dr. A.S. Chaurasia
Department of Chemical Engineering
Date: 19/09/2022

2. Co-gasification
of Rice Straw
and LDPE

3. Objectives
To study the changes in the gasification process by the addition
of polymer to biomass
To study gas composition and tar,char weights

4. Biomass
Gasification
At high temperatures and in the
presence of air, biomass is converted
into useful gases such as methane
and hydrogen. This is a fast and
efficient method for the conversion of
biomass into a high calorific value
fuel.

5. Gasification
Reaction Scheme
Khonde R, Chaurasia A, Rice husk gasification in a two-stage fixed-bed gasifier: Production of
hydrogen rich syngas and kinetics, InternationalJournal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.03.138

6. Reaction conditions
● The temperature for the pyrolysis
section is maintained at 500 oC and
the temperature of the gasification
section is maintained at 800 oC. These
values are reported as optimum values
in previous studies using this reactor.
● The combination of nitrogen for
pyrolysis section and air for the
gasification section is chosen as they
give the highest yield of hydrogen.
Khonde R, Chaurasia A, Rice husk gasification in a two-stage fixed-bed gasifier: Production of
hydrogen rich syngas and kinetics, InternationalJournal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.03.138

7. Co - gasification of biomass with plastic
● Co-gasification of biomass with plastic
(waste plastic) has several
advantages over traditional
gasification.
● The first advantage is that the supply
of biomass is seasonal, a facility that
can also use waste plastic as
feedstock has an advantage.
● Using waste plastic also leads to a
product gas that is richer in hydrogen
as the following graph published by F.
Pinto et al. shows.
F. Pinto et al./ Fuel 81(2002) 291-297

8. Choice of plastic
● LDPE makes up a major chunk of
plastic waste in municipal solid waste.
● It was also readily available (as waste
bubble wrap) in our lab.
● C. Cao et al. ( reported the gasification
efficiency of different polymers as
PE > PC = PP > ABS
Table source : International Journal of Design Sciences and
Technology,Volume 22 Number 2(201 6) ISSN 1 630-7267

9. Experimental
Procedure
01
LAB PROCEDURE

10. Assembly
Pyrolysis
section
Attache 3
Throat
section
Attache 2
Gasification
section
Attache 1

11. Step 1:Feed preparation
1. We prepare the feed
Rice straw→Cut it into small pieces
Grind it in a mixer
Sieve it
Oven dry it
Polymer(LDPE) → Cut it into small squares of approx 1
cm2
1. Weighing
We store our feed in batches of 25g rice straw and
variable amount of plastic in each batch in air tight bags

12. Step 2:Assemble
1. PYROLYSIS CHAMBER
● The pyrolysis chamber is made leak proof (viz-a-
viz,feed leak) using three meshes [two square meshes
pushed in; one circular mesh below the above two(for
the periphery)].
● Now the feed is fed to the chamber from above
● We proceed to break ice and put it into the drum where
tar is condensed (¼ by height of the drum) & seal it.
● A mesh is put between the gasket and the given
structure
● Now, the gasification chamber is affixed first(using nuts
& bolts on the given structure.

13. Cont.
2.THROAT
After,[1] we affix the throat on the gasification chamber.
3.PYROLYSIS CHAMBER
The pyrolysis chamber is affixed over the throat(,also a mesh
is put between the two chambers)
4.
The instrument for intermittent feeding is affixed over the
pyrolysis chamber
5.VALVE
The valve along with its pipe is attached to the drum,for
collecting gas in the tedlar bag.

14. Step 3:Wiring & Heating
1.Wiring
The wires are colour coded i.e. our seniors have left some
markings.
The red wires go in the hole marked ‘R’;The black wires, ‘B’
marked hole;The green wires (*2) are for earthing [wound at
the back of the assembly(,on the support)]
2.Heating
After the wiring is done,we switch on the heating controller for
the gasification section, & after it reaches 300 °C (,in about 20
min),we switch on the heating controller for the pyrolysis
section.
LS
US

15. Step 4:Gas collection
1.Flow rates
When the temp. Of the pyrolysis section reaches 300 °C we
start the air flow (0.5 LPH ) and nitrogen flow (0.2 LPH).
Now we also connect a tedlar bag to the pipe attached to the
valve on the drum for gas collection.
The heating of the system is concluded when the upper
section reaches 500 and the lower section reaches 800.
Note:The throat is connected to the upper section for its own
heating.

16. Step 5: Tar & Char collection
1.Tar
● After the reactor is cooled,we start disassembling the stages .
● In the U-tube type of structure attached to the bottom of the the drum head,we put approx
40 ml chloroform and shake the structure well.
● The tar chloroform solution is poured into another beaker;again,we add chloroform for
2nd washing.
● Later,the chloroform is evaporated from the mixture using suitable equipment.
2.Char
The leftover char in the pyrolysis chamber is collected in an airtight bag and is weighed.

17. Cont.
Run 1: 2.5g LDPE
+
25g rice straw
[11.33 g char]
Run 2: 1.25g LDPE
+
25g rice straw
[11.25 g char(1g
trapped in the mesh)]
Run 3: 3.75g LDPE
+
25g rice straw
[11.68 g char]
Run 4: 5g LDPE
+
25g rice straw
[16.16 g char]
**-1 g from wt.[wt. Of plastic bag].
**+0.5 g (approx) char got wasted.

18. Cont.
**-23.16g from each(to account wt.
Of container).
Run 1: 2.5g LDPE
+
25g rice straw
[13.23 g Tar]
Run 2: 1.25g LDPE
+
25g rice straw
[15.81 g Tar]
Run 3: 3.75g LDPE
+
25g rice straw
[23.62 g Tar]
Run 4: 5g LDPE
+
25g rice straw
[26.19 g Tar]

19. Issues faced
Current situation
1 2 3 4
Problems
Reactor
leakage
Dearth of N2 Gasket leak
Small space
in the reactor
We are going good

20. Cont.
Reactor malfunction Reactor malfunction Gasket leak

21. Preliminary
Results
03

22. A sample gas chromatogram

23. Weight of Tar vs Weight of LDPE added

24. Thank You