+ All Categories
Home > Documents > Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek

Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek

Date post: 14-Jan-2017
Category:
Upload: vudan
View: 222 times
Download: 1 times
Share this document with a friend
12
Transcript
Page 1: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek
Page 2: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek
Page 3: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek
Page 4: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek
Page 5: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek
Page 6: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek
Page 7: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek
Page 8: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek

ICCHT2010 - 5th

International Conference on Cooling and Heating Technologies. Bandung, Indonesia

9-11 December 2010

123- 1

The Development of Laboratory Scale Continuous Peat

Torrefaction Reactor System

Haryadi1, Aryadi Suwono, Toto Hardianto, Ari D. Pasek2

1Mechanical Engineering, Politeknik Negeri Bandung, Bandung, Indonesia,

[email protected]

2Faculty of Mechanical and Aerospace Engineering, ITB, Bandung, Indonesia,

[email protected], toto@pau pauir.itb.ac.id, [email protected]

ABSTRACT: Peat can be fourth energy resources in Indonesia, after oil coal and

natural gas. With 27 million hectares, Indonesia peat resources area is the third

largest in the world, after Canada and Russia. In the current years, peat utilization

as energy is very limited. The development of peat energy resources is expected to

support the objective of the National Energy Management Blueprint 2006-2025.

However, the environmental aspect of this matter should be emphasized

Torrefaction is a thermal process appiled to organic materials operated at medium

temperature, in absence of oxygen and at relatively long residence times, typically

10 to 60 minutes. The properties, such as heating value, fix char content, are

improved through limited devolatilisation that occurs under these conditions. Batch

torrefaction experiment showed that the heating value of the torrefied peat was at

the level of subbitminuous C to bituminuous high volatile C of ASTM D 388 coal

classification.

A development of a laboratory scale continuous peat torrefaction reactor system

will be presented. The capacity of the system is 8 kg/h of raw material. The system

consists of a dryer, a torrefaction reactor, and supporting facilities. Both the dryer

and the torrefaction reactor employed fluidized bed. The dryer worked in bubling

regime, while the torrefaction reactor worked in near minimum fluidization

condition.

The raw material of the system was natural peat with 46 % moisture content. The

dryer used hot drying air to reduce peat moisture content to 22.7%. The torrefaction

bed employed heating steam to increase peat temperature to 300°C. The peat was

held at this tempemparature for 15 - 30 minutes. The drying air was heated up with

waste steam from the torrefaction reactor. The experiment showed that the torrefied

peat heating value was 5720 kcal/kg.

Keywords: peat, continuous, torrefaction, system, development.

1. INTRODUCTION

Oil, coal, and natural gas still become primary energy resources. The world oil consumption

in year 1965 had already reach 31.25 million barrels per day, while Indonesian oil consumption

is 123,000 barrel per day. Meanwhile, in year 2004, the world oil consumption increased to

Page 9: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek

ICCHT2010 - 5th

International Conference on Cooling and Heating Technologies. Bandung, Indonesia

9-11 December 2010

123- 2

80.76 million barrel per day and for Indonesian 1.15 milion barrel per day [1]. The increase of

world population and developement of technology cause energy consumption rises rapidly.

Therefore, alternative energy resources must be developed with equivelent quality as oil, coal

and natural gas.

For Indonesia, peat could become the new source of energy after the three primary sources

mentioned above, because Indonesia is the third lagest peat area reserve in the world. The area

of peat reserve proximately 27 million hectares [2], with potential reserve equal to 200 billion

ton [3]. However, due to peat low quality as source of energy, it requires to be improved in

order to be used as new energy recources. An environmental impact analysis also should be

conducted if the usage of peat will be realized massively.

Theoretical and experimental researches on upgrading the quality of peat as solid fuel

through drying method have been conducted [4]. Further theoritical study indicates that energy

density of peat still can be improved with advanced treatment, so called torrefaction process.

Therefore this research will study the upgrading of peat quality as source of energy, especially

increasing its heating value, through torrefaction process. Based on latest research, application

of this method to wood briquette can improve its HHV up to 15% [5], while empty oil palm

bunches up to 25% [6]. Improvement of peat heating value by torrefaction process can be as

high as heating value of bituminous coal [7].

Long term research focussing on increasing the quality of peat as solid fuel should be

conducted to improve economic value of peat. To achieve this goal, several stages of research

are still required. This research is only representing the early stage, which main goal is to

examine the influence of process temperature and time reaction to thermodynamics properties

of product in peat torrefaction process.

2. PEAT TORREFACTION

Torrefaction is a method of thermochemical process to increase solid fuel heating value,

especially an organic matter. In biomass torrefaction process, the organic matters experience

treatment of heat at medium temperature in a condition without oxygen, with target to increase

its energy density by decomposition of certain fractions. The effect of decomposition process is

expected to degrade atomic ratio of oxygen to carbon, hence the heating value will increase.

Some factors that influence the product characteristic in torrefaction process are process

temperature, resident time, and particle size. The product from torrefaction process can be used

directly (such as solid fuel briquett), mixed together with other fuel (co-combustion), or as raw

material for gasification.

The main fractions of biomass are: hemicelluloses, lignin and cellulose, which all together

called lignocelluloses. Hemicelluloses decomposes at a temperature of 225 to 325 °C, cellulose

decomposes at a temperature of 305 to 375 °C, and lignin decomposed at a temperature of 250

to 500 °C [8]. Among the three compounds of lignocelluloses, hemicelluloses are the most

reactive fraction, and the most easily decomposed. Concentration of hemicelluloses in biomass

is quiet high. Biomass torrefaction process is aimed to decompose hemicelluloses. Therefore,

the process temperature of biomass torrefaction is approximately same with biomass

hemicelluloses decomposition temperature, which is between 225 to 300 °C [5, 6, 8].

Naturally, peat is partially or incomplete decomposed biomass and deposited together with

complementary minerals. Like other organic fuels, main constituent of peat are carbon (C),

oxygen (O) and hydrogen (H). If peat decomposition level is high, the content of C will

increase and the content of O will decrease. Peat contains much less hemicelluloses than

biomass. Thus, the torrefaction process of peat must be done at slightly higher temperature than

biomass torrefaction process [7].

Page 10: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek

ICCHT2010 - 5th

International Conference on Cooling and Heating Technologies. Bandung, Indonesia

9-11 December 2010

123- 3

3. PEAT TORREFACTION SYSTEM

The system consist of a dryer, a torrefaction reactor, and supporting facilities. Both the

dryer and the torrefaction reactor employ fluidized bed method for each the process. The dryer

worked in bubling regime, while the torrefaction reactor worked in near minimum fluidization

condition. The system capacity is design for 8 kg/h, which is determined based on drying bed

capacity that already exists.

The dryer uses hot drying air to reduce peat moisture content and increase peat temperature

from ambient temperature to process temperature. The torrefaction reactor uses superheated

steam to increase peat temperature to 300°C. The torrecation reactor inert atmosphere is

provided by the steam release from the peat it self, which is originated from peat moisture. The

dried peat is held at this temperature for 15 - 30 minutes.

4. THE APPARATUS

The schematic of material flow of the laboratory-scale peat continuous torrefaction system

is shown in Figure 1. A screw conveyor conveys raw material to the driying bed, then the peat

flown from driying bed to torrefaction bed. Heating steam came into internal heater of

torrefaction bed, then into external heater, and finally into drying air heater. A blower drives

fresh air to the air heater. The air heater is finned tube heater, with the heating steam is in the

tube side. The hot air came into the plenum, and than passes a distributor plate to the drying

bed. Dry peat was entrained by drying air to the freeboard. As freeboard cross sectional area

greater than that of drying bed, drying air velocity decreased into below the terminal velocity

of the dry particles, then the dry particles fall into incline plate. The plate inclination is 45°, to

ensure that the peat goes down.

Figure 1: Schematic of the developed apparatus.

A rotavalve was acting as airlock or barrier, which prevent drying air goes into torrefaction

bed and hot gas of the torrefaction reactor goes into drying bed. The rotavalve consists of: a

two side segmental cut cylindrical housing, and finned rotating shaft. The clearance between

housing and fin was about 1 mm.

Page 11: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek

ICCHT2010 - 5th

International Conference on Cooling and Heating Technologies. Bandung, Indonesia

9-11 December 2010

123- 4

Figure 2 shows schematic diagram of the torrefaction bed arrangement. The bed cross

section is rectangular. The internal heater pipe was installed in longitudinal position to reduce

disruption of material flow. Resident time of the peat was adjusted with inclination angle

adjusment of the distributor. And flow distribution of the hot gas was adjusted with regulator

plate. Another rotavalve was installed at the outlet side of the bed to separate hot torrefaction

gas from sorounding atmosphere.

All hot parts of the system apparatus were thermally insulated.

At the bigining, superheated steam was injected to the torrefaction bed to remove air and

heat up the bed. Under the operating condition, hot steam originated from peat provided inert

atmosphere in the torefaction bed.

Figure 2: Torrefaction bed arrangement.

4. RESULT AND EVALUATION

Mass flow rate of the peat raw material was 8 kg/h with 46% moisture content (AR). Drying

air flow rate was 238 kg/hr, with 83°C temperature. Heating steam flowrate, pressure and

temperature was 13 kg/hr, 2 atm, and 490°C respectively. The torrefaction temperature was

300 °C. About 20 minutes after feeding, the product started to appear. The torrefied peat

heating value increased from 2673 kcal/kg to 5720 kcal/kg. The product calorific value is

equivalent to about 30 minutes resident time in batch torrefaction experiment.

Figure 3 shows flowsheet model of AspenPlus 11TM

simulation of the experiment. The

drying bed is represented by DRY-REAC and DRY-FLASH block, and torrefaction bed is

represented by B1, TRF and GAS-SPTR block. The torrefaction gas composition was

generated from a batch torrefaction experiment.

There is very good agreement betwen the Aspen model and the experiment in drying

process. For the torrefaction process, decreasing temperature from HDRYPEAT to PRD-TGSS

strem indicated that the process was endothermic. This phenomenon needs further

investigation.

Page 12: Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek

ICCHT2010 - 5th

International Conference on Cooling and Heating Technologies. Bandung, Indonesia

9-11 December 2010

123- 5

Figure 3: AspenPlus 11

TM model of the experiment.

5. CONCLUSION AND RECOMENDATION

The intial model of laboratory scale torrefaction system apparatus has beed developed. The

experiment showed that the heating value increased significantly. To reduce air leak from the

drier to the torrefaction bed, better rotavalve with smaller clearance should be developed.

Greater capacity also makes smaller leak. The mathematical model of crossflow fluidizedbed

should be developed for this porpouse.

REFERENCES

[1]Davies, Peter. 2005. BP statistical review of world energy 2005. UK.

[2] International Peat Society (IPS), 2003. 2004. Peat as a Resource, available at

www.peatsociety.fi. Finland.

[3] Bappenas, --------------, dari Bappenas http://www.bappenas.go.id/. Indonesia.

[4] Haryadi, Suwono, A., and Hardianto, T. 2006. Experimental study on continuous Fluidized

Bed Drying of Peat, Proc. Sem. International Confrence on Fluid and Thermal Energy

Conversion. Indonesia.

[5] Felfli , Felix F., Luengo, Carlos A., Suárez, Jose A., Beatón, Pedro A. 2005. Wood briquette

torrefaction, Energy for Sustainable Development, l IX-31, 19-22. India.

[6] Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek. 2008. Heating Value

Improvement of Palm Empty Fruit Bunch as Solid Fuel through Torrefaction Process, Proc.

Sem. Int. Conf. Cooling and Heating Tech. 2008. South Korea.

[7] Haryadi, Aryadi Suwono, Toto Hardianto, Ari Darmawan Pasek. 2010. Heating Value

Improvement of Peat to Coal Level through Torrefaction Process, International Journal of

Energy Machinery, Vol. 3(1), Agustus 2010, pp. 32 – 37.

[8] Prins, Mark J., Ptasinski, Krzysztof J., Janssen, Frans J.J.G. 2006. Torrefaction of wood part

1. Weight loss kinetics, J. Anal. Appl. Pyrolysis, Vol. 77, 28-34. The Netherland.

[9] Toto Hardianto, Haryadi, Willy Ardiansyah, Riza Azhari, Ari D. Pasek, Aryadi Suwono.

2009. The Simulation of a Laboratory Scale Peat Continuous Reactor Torrefaction System,

Proc. International Conference on Fluid and Thermal Energy Conversion 2009. South

Korea.

[10]Aspen Technology, Inc.. 2001. Aspen Plus, Getting started modeling process with solid”,

Cambridge, Massecussets. USA.


Recommended