d Energy Development
Programme in Asia
Tel: 66-2-280 2760
c/o FAO Regional Offcie for Asia and the Pacific
Fax: 66-2-280 0760
Maliwan Mansion, Phra Atit Road,
E-mail: rwedp@fao.org
Bangkok, Thailand
Internet: http://www.rwedp.org
The designations employed and the presentation of material in this publication do not imply
the expression of any opinion whatsoever on the part of the Food and Agriculture Organiza-
tion of the United nations concerning the legal status of any country, territory, city or area or
of its authorities, or concerning the delimitations of its frontiers or boundaries.
The opinions expressed in this publication are those of the author(s) alone and do not imply
any opinion on the part of the FAO. F
OREWORD
In April 1995 an International Workshop on Biomass Briquetting was organised by the
Department of Chemical Engineering of the Indian Institute of Technology-Delhi. The Workshop
was sponsored by the Technology and Development Group of the University of Twente, The
Netherlands, and the Indian Renewable Energy Development Agency Ltd., India. The Workshop
reported the main results of the Biomass Densification Research Project, which was jointly
implemented by the two named universities and two private sector companies (Solar Sciences
Consultancy Pvt. Ltd, and DENSI-TECH). Results from briquetting activities in other countries
in Asia were also reported, and various technical and financial aspects of briquetting were
addressed in the International Workshop. The Proceedings of the Workshop were published by
RWEDP in 1996.
It is clear from the Workshop that substantial progress has been made in briquetting technology
and practices in recent years. RWEDP considers briquetting of biomass residues for fuel an
important option for substitution of wood and loose biomass residue fuels, under certain
conditions. However, the option should be carefully evaluated and any implementation should
be based on a thorough understanding of the requirements and constraints.
The Field Document on Biomass Briquetting: Technology and Practices has been prepared by
P.D. Grover and S.K. Mishra of IIT-Delhi, and published by RWEDP as a complement to the
named Proceedings. The publication may help readers to further familiarise themselves with the
technology and practices of biomass briquetting.
Dr. W.S. Hulscher
Chief Technical Adviser iii
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ONTENTS
Page
FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. POTENTIAL AGRO-RESIDUES AND THEIR CHARACTERISTICS . . . . . . . . . . . . . . 4
2.1 Potential Agri-residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Appropriate Biomass Residues for Briquetting . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. FUNDAMENTAL ASPECTS OF BRIQUETTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Pressure Compaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2 Binding Mechanisms of Densification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3 Mechanism of Compaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. BRIQUETTING TECHNOLOGIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Screw Press and Piston Press Technologies . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2 Other Briquetting Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3 Compaction Characteristics of Biomass and Their Significance . . . . . . . . . . . 12
4.4 Unit Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5 Briquetting Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.6 Material Processing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.7 Briquette Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5. LATEST DEVELOPMENTS INCLUDING FEED PREHEATING . . . . . . . . . . . . . . . . 22
5.1 Essentials of Preheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2 Preheating Phenomenon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.3 Preheater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6. MATERIAL AND ENERGY BALANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.1 Prerequisite Step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.2 Feed Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.3 Preheater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.4 Briquetting and Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.5 Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.6 Information Flow Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.7 System Material Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.8 Amount of Briquettes for Furnace (Energy Balance) . . . . . . . . . . . . . . . . . . . 32
6.9 Process Data for Typical Production Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.10 Electrical Power Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 iv
7.
PROCEDURE FOR SETTING UP A BRlQUETTlNG PLANT . . . . . . . . . . . . . . . . . . 35
7.1
Initial Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.2
Feasibility Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.3
Project Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.4
Start-up Operation and Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.5
Manpower Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8.
ECONOMIC ANALYSIS OF BRIQUETTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
8.1
Typical Cost Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
9.
APPLIANCES FOR BIOMASS BRIQUETTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
9.1
Combustion in Stoves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
9.2
Combustion in Furnaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
9.3
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
10.
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 1. I
NTRODUCTION
Many of the developing countries produce huge quantities of agro residues but they are used
inefficiently causing extensive pollution to the environment. The major residues are rice husk,
coffee husk, coir pith, jute sticks, bagasse, groundnut shells, mustard stalks and cotton stalks.
Sawdust, a milling residue is also available in huge quantity. Apart from the problems of
transportation, storage, and handling, the direct burning of loose biomass in conventional grates
is associated with very low thermal efficiency and widespread air pollution. The conversion
efficiencies are as low as 40% with particulate emissions in the flue gases in excess of 3000
mg/Nm³ In addition, a large percentage of unburnt carbonaceous ash has to be disposed of. In
the case of rice husk, this amounts to more than 40% of the feed burnt. As a typical example,
about 800 tonnes of rice husk ash are generated every day in Ludhiana (Punjab) as a result of
burning 2000 tonnes of husk. Briquetting of the husk could mitigate these pollution problems
while at the same time making use of this important industrial/domestic energy resource.
Historically, biomass briquetting technology has been developed in two distinct directions. Europe
and the United States has pursued and perfected the reciprocating ram/piston press while Japan
has independently invented and developed the screw press technology. Although both
technologies have their merits and demerits, it is universally accepted that the screw pressed
briquettes are far superior to the ram pressed solid briquettes in terms of their storability and
combustibility. Japanese machines are now being manufactured in Europe under licensing
agreement but no information has been reported about the manufacturing of European machines
in Japan.
Worldwide, both technologies are being used for briquetting of sawdust and locally available
agro-residues. Although the importance of biomass briquettes as substitute fuel for wood, coal
and lignite is well recognized, the numerous failures of briquetting machines in almost all
developing countries have inhibited their extensive exploitation.
Briquetting technology is yet to get a strong foothold in ma