Design and construction of briquetting making machine

Briquetting Process
Briquetting is defined as the densification (agglomeration) of an aggregate of loose particles into a rigid monolith (Mordi, 2007). Briquetting was first proposed in Russia by a Russian inventor F.P Veshniakov (Prokhorov, 1982). Veshniakov developed a method of producing briquettes from waste wood, charcoal and hard coal. The most important advantages of briquette are its low sulphur content, relative freedom from dust, ease of handling and high calorific value (Osarenmwinda and Imoebe, 2006). Zhanbin (2003) stated briquetting as a high-pressure process which can be done at elevated temperature. Wilaipon (2008) and Olorunnisola (2007) defined briquetting as a process of compaction of residues into a product of higher density than the original material. According to Davies (1985), during the first and second World Wars, households in several European countries employed a simple lever-operated briquetting press that used soaked waste paper and other combustible domestic waste as a feed stock. Today's industrial briquetting machines, although much larger and more complex, operate on the same general principles.
In a work by Okey et al. (2014) on biomass briquetting and rural development in Nigeria, it was stated that the constraint in the advancement of biomass briquetting in African and in Nigeria particularly has been associated with the development of briquetting press for local commercial manufacture. The development of appropriate briquette machines for rural communities should go beyond designs for household use to commercial scale. Some of the commercial limitations associated with existing machines are:
i. The dependence on human strength for direct application of pressure for biomass densification making them gender sensitive and producing poor quality briquettes.
ii. Low production capacities making them unprofitable for commercial use. The low production capacity is mostly associated with the time spent on the ejection of the compressed biomass from the moulds.
iii. Lack of commercial scale-up capabilities hence the machines are limited to household use making the marketing of the briquettes unprofitable. The numerous failures of these machines have been recorded due to attempts to use them for commercial production of briquettes. Thus, they have been limited in their use due to their inappropriateness for commercial production of briquettes. All of these aforementioned problems need to be addressed before significant progress can be made in biomass briquetting in Nigeria.
2.1.1 Classification of Briquetting Process
Basically, there are two major ways of classifying briquetting processes. One distinction is divided into two principal ways, which is with or without binders. In binder less briquetting, the materials are simply compressed without addition of adhesive (Mangena and Camn, 2007).
The second way of classifying follows the pressure applied while briquetting which may be:

1. High pressure which has pressure of above 100MPa
2. Medium pressure with pressure between 5-100MPa
3. Low pressure having pressure of up to 5MPa
   2.2 Briquettes Production
   2.2.1 Briquettes
   A briquette as a block of compressed coal, biomass or charcoal dust that is used a fuel to start and maintain fire it can be otherwise stated as a block of compressed combustible energy carrier suitable for heating. Briquettes are made from waste materials such as old newspaper, sawmill wastes or partially compressed biomass waste. Briquettes are largely combustible materials made from loose or low density wastes but compressed together into a solid. Increasing demand for alternative energy sources aside from charcoal and petroleum products as well as waste disposal challenges has led to increased interest in the production of briquettes (Arinola et al., 2013). At the beginning of 19th century, sawdust briquettes were made with tar or resins as the binders, but could not gain importance at that time due to relatively higher costs compared to wood and charcoal. But re-emerged in the 1950s when millions of tons of briquettes were produced and consumed (Lardinios and Klundert, 1993).
   2.2.2 Application of Briquettes
   Briquettes are widely used for any type of thermal application. It can at any point replace conventional fuels at any thermal applications. It can be used by the industrial, commercial and household sectors.
4. It can be used in homes for cooking and other heating.
5. It is suitable for metal heating and melting in forge
6. The gas can be used to generate power i.e. fuel for gastifiers to generate electricity
7. It can be used to power steam boilers in generating steam.
   In the industries, the briquettes can be utilized in thermal application.
   2.2.3 Advantages of Briquettes Production
8. There would be less wastes dump in the streets
9. Less pollution produced in burning of wastes
10. This will create wealth from waste and provide sources of revenue for some people and the government through personal income tax (Arinola et al., 2013)
11. The high demand for fire wood would reduce which would lead to conservation of trees in the forests
12. Create employment opportunities for people since people will be needed to operate the briquette machine, get the raw materials (i.e. coal and agro-residue, etc.) sell the briquettes produced, etc. (Bhattacharya, 1985)
13. It will help to minimize the environmental hazard from agrowaste (Osarenmwinda et al., 2012)
    2.3 Briquette Making Raw Materials
    A lot of agricultural residues and wastes are generated in the country, but they are poorly utilized and badly managed, since most of these wastes are left to decompose or they are burned, resulting in environmental pollution and degradation (Jekayinfa and Omisakin, 2005). These agricultural residues and wastes are potential raw materials for briquetting.
    Biomass resources in the country include Agricultural crops, wood, charcoal, grasses and shrubs, residues and wastes (agricultural, forestry, municipal and industrial), and aquatic biomass. Total biomass potential in Nigeria, consisting of animal and agricultural waste, and wood residues, was estimated to be 1.2 PJ in 1990 (Obioh and Fagbenle, 2009). In 2005, research revealed that bio-energy reserves/potential of Nigeria stood at: Fuel wood 13071,464 hectares, animal waste, 61 million tonnes per year, crop residues, and 83 million tonnes (Agba et al., 2010). In Table1 the estimated national output of the processing based biomass residues in 2004, in metric tonnes is recorded. Some materials have been successfully used by some researchers. Yahaya and Ibrahim (2012); Sengar et al. (2012) produced briquettes from rice husks, Sengar et al. (2012) made briquettes with de-oiled cashew shell. Yousif and Ahmed (2006) used cotton stalks that were carbonized. Oladeji (2012) made comparative study of briquetting of some agro-residues that included; cassava peel, corncob and melon shell. Also Oladeji (2013) made use of sawdust, rice husks and melon shell in investigating the viability of their briquettes. Saw dust, coco peat and almond leaves were separately used in making briquettes by Raju et al. (2014).
    In general, any material that will burn but is not in a convenient size, shape, or form to be readily usable as fuel is a good candidate for briquetting. It may be necessary or desirable to make briquettes of more than one material (Davies, 1985) as Olorunnisola (2007) produced fuel briquettes from waste paper and coconut husk admixtures. Many other materials that can be used for briquetting including: coffee husks, coal dust, olive residues, corn stalk, palm husks, nut shells, paper waste, coconut fibres and charcoal fines. In a list, briquette making raw materials are but not limited to:
14. Rice husks and straws
15. Corn cobs and stalks
16. coffee husks
17. coal dust
18. olive residues
19. corn stalk
20. palm husks
21. nut shells
22. paper waste
23. coconut fibres
24. charcoal fines
25. Wood shavings (sawdust) - the mass flow of wood waste generated in southwest Nigeria is shown in table 2.