Kỷ yếu hội nghị khoa học và công nghệ toàn quốc về cơ khí - Lần thứ IV

A STUDY ON FACTORS THAT AFFECT ON THE FIXED BED
GASIFICATION PROCESS
NGHIÊN CỨU MỘT SỐ YẾU TỐ ẢNH HƯỞNG ĐẾN QUÁ TRÌNH KHÍ HÓA TRẤU
TẦNG CỐ ĐỊNH
Hoang An Quoc1a, Nguyen Vu Lan1b, Nguyen Thanh Quang2, Nguyen Ngoc Tuyen3c
1
HCMC University of Technology and Education, HCMC, Vietnam
2
HCMC University of Technology, HCMC, Vietnam
3
Industrial University of HCMC, HCMC, Vietnam
a
b
; ;
ABSTRACT
The rice husk gasification technology in Vietnam has been focusing on applications
inlife and industrial production.This article presents an experimental investigation on impacts
of two key system variables, air speed in the incinerator and humidity of rice husk fuel, on the
system efficiency. Results have shown that higher humidity of input husk fuel will lead to
lower system productivity or may even stop the burning process. Meanwhile, only at a
specific suitable and limited inlet air velocity range can the overall gasification efficiency
reach to its maximum value.
Keywords: fixed bed gasification; biomass gasification; gasification technology; rice
husk gasification.
TÓM TẮT
Công nghệ khí hóa trấu ở nước ta hiện nay đang được quan tâm và đưa vào ứng dụng
trong đời sống và sản xuất. Bài báo này giới thiệu nghiên cứu thực nghiệm về ảnh hưởng của
hai tham số chủ yếu của hệ thống, tốc độ khí trong lò đốt và độ ẩm của nhiên liệu trấu, tới
hiệu suất của hệ thống khí hóa trấu tầng cố định. Kết quả chỉ ra rằng độ ẩm của trấu đầu vào

gaseous product is a mixture of CO, H2, CH4 which are flammable gases and several useful
components such as tar and dirt.
2.2. Main reaction equations in gasification
In most of the cases, the following chemical reactions may take place in the gasification
process:
C + O2

CO2

(1)

2H2 + O2

2H2O

(2)

C + 1/2O2

CO

(3)

C + 2H2

CH4

(4)

CO + 3H2

Kỷ yếu hội nghị khoa học và công nghệ toàn quốc về cơ khí - Lần thứ IV
The experimental model was designed and manufactured according to the principle
diagram shown in Figure1. Rice husk was continuously supplied from the feeder through a
screw into the combustion chamber. To ensures table temperature and avoid heat loss,
combustion chamber was covered thoroughly by glass fiberlayers. After gasification process
had taken in the burner, the gas was filtered through acyclone and then blown into cooler
sandtar filters. Finally, the gas was dehumidified before moving to the burner’s nozzle.
3.2. Input data and analysis
The following parameters were used to analyze the performance of the gasification
system:
- Air velocityin combustion chamber Va[cm/s]: Because of the lack of special
equipment, this parameteris calculated in directly via the airflow at the output of the blower.
- Huskhumidity Hu [%]: Humidity has a great influence on combustion process, so in
the gasification system, the moisture of the fuel is a vital parameter. Relative humidity of the
material is as the ratio between the amount of moisture contained in the material and the
volume of material.
- Heat total value Qh [Kcal]: Heat total of husk is calculated basing on the weight of
consumed husk mh [kg] and the heat value per each mass unit of the husk qh[Kcal/kg] as
shown in Eq.(9).
Qh = mh.qh

(9)

- Useful heat Qu [Kcal]: is the heat received when burning the gaseous product. Using
this value and the Heat total value, one may infer the efficiency of the gasification process by
Eq.(10).
(%) = Qu/Qh×100%

(10)



1

1.05

3,397.68

0.00

0,00

2

2.55

3,397.68

441.70

13.00

515


Kỷ yếu hội nghị khoa học và công nghệ toàn quốc về cơ khí - Lần thứ IV
3

4.05

3,397.68


312.59

9.20

7

10.06

3,397.68

299.00

8.80

4.2. Effect of humidity husk
The dependence of the process efficiency on humidity of input fuel was tested by some
other experiments in which air velocity was fixed at the above-mentioned best value, initial
volume of heated water was 5kg each time and 5 husk samples with humidity value from 10 –
40 % were investigated. The results are shown in Table 2 and Figure 2. As explained above,
these results revealed the variation trend of this relationship. The higher the humidity was, the
more difficult for ignition process and gasification, thus, the lower the system efficiency. If
the humidity was too high, the equipment was unable to operate and the gasification could not
take place. Obviously, it was the large amount of water stored inside the input fuel prevented
the flame of gasification. Although the lower humidity the better performance, the lower
humidity requires more initial treatment which in turn need extra energy consumption. That
means this humidity preparation will pull down the overall efficiency. Besides, the humidity
value depends very much on geographic location and climate condition of the application cite.
Accordingly, a further research on an opitimized working condition should be done to
ameliorate the current gasification process.

428.11

12.60

3

25.10

3,397.68

295.60

8.70

4

31.60

3,397.68

81.54

2.40

5

40.50

3,397.68


Figure 2. Velocity - Efficiency Chart
516

10.06


Kỷ yếu hội nghị khoa học và công nghệ toàn quốc về cơ khí - Lần thứ IV
Humidity - Efficiency Chart
16.00

Efficiency %

14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
10.50

17.30

25.10

31.60

40.50


Biomasse, Verfahren – Transparenz – Modellierung, 20. Deutscher Flammentag Essen
2001, VDI-Berichte 1629, S.521-526.
[2] Anil K. Rajvanshi, Biomass Gasification,
Institute,Phaltan-415523, Maharashtra, India.

Nimbkar

Agricultural

Research

[3] Thành B.T., Tuyên N.V., Hoài L.Đ.N., Nghiên cứu tính toán thiết kế buồng đốt trấu hoá
khí quy mô nhỏ sử dụng cho hộ gia đình nông thôn, Tạp chí Cơ khí Việt Nam, số tháng
7/2012.
[4] Thành B.T., Thiết kế ghi phân phối tác nhân khí cho máy sấy muối tinh tầng sôi liên tục,
Tạp chí năng lượng nhiệt Việt Nam, số tháng 5/2010.
[5] Quang N.T., Hùng Đ.T., Nghiên cứu chế tạo hệ thống hóa khí than tầng cố định ngược
chiều, Tạp chí KH & CN Nhiệt, số 77, tháng 09/2007.
[6] Quang N.T., Quốc H.A., Thông N. T., Nghiên cứu khí hóa trấu lớp cố định nhằm sản
xuất điện năng, Tạp chí KH & CN Nhiệt, số 102, tháng 11/2011.
AUTHOR’S INFORMATION
Author 1: Hoang An Quoc, HCMC University of Technology and Education, HCMC,
Vietnam, Email: , Phone: 0908197416
Author 2: Nguyen Vu Lan, HCMC University of Technology and Education, HCMC,
Vietnam, Email: ,Phone: 0913522142
Author 3: Nguyen Thanh Quang, HCMC University of Technology, HCMC, Vietnam,
Author 4: Nguyen Ngoc Tuyen, Industrial University of HCMC, HCMC, Vietnam, Email:


518