Constituents of charcoal briquettes
- Wood charcoal (fuel)
- Mineral char (fuel)
- Mineral carbon (fuel)
- Limestone (ash colorant)
- Starch (binder)
- Borax (release agent)
- Sodium nitrate (accelerant)
- Wax (some brands: binder, accelerant, ignition facilitator).
- Chaff (Rice chaff and peanut chaff)
Some briquettes are compressed and dried brown coal extruded into hard blocks. This is a common technique for low rank coals. They are typically dried to 12-18% moisture, and are primarily used in household and industry.
In Ireland, peat briquettes are a common type of solid fuel, largely replacing sods of raw peat as a domestic fuel. These briquettes consist of shredded peat, compressed to form a virtually smokeless, slow-burning, easily stored and transported fuel. Although often used as the sole fuel for a fire, they are also used to quickly and easily light a coal fire.
Biomass briquettes are made from agricultural waste and are a replacement for fossil fuels such as oil or coal, and can be used to heat boilers in manufacturing plants, and also have applications in developing countries. Biomass briquettes are a renewable source of energy and avoid adding fossil carbon to the atmosphere.
A number of companies in India have switched from furnace oil to biomass briquettes to save costs on boiler fuels. The use of biomass briquettes is predominant in the southern parts of India, where coal and furnace oil are being replaced by biomass briquettes. A number of units in Maharashtra (India) are also using biomass briquettes as boiler fuel. Use of biomass briquettes can earn Carbon Credits for reducing emissions in the atmosphere. Lanxess India and a few other large companies are supposedly using biomass briquettes for earning Carbon Credits by switching their boiler fuel. Biomass briquettes also provide more calorific value/kg and save around 30-40 percent of boiler fuel costs.
A popular biomass briquette emerging in developed countries takes a waste produce such as sawdust, compresses it and then extrudes it to make a reconsistuted log that can replace firewood. It is a similar process to forming a wood pellet but on a larger scale. There are no binders involved in this process. The natural lignin in the wood binds the particles of wood together to form a solid. Burning a wood briquette is far more efficient than burning firewood. Moisture content of a briquette can be as low as 4%, whereas green firewood may be as high as 65%.
|Briquette density, t/m³||1,0-1,2|
|Heat content, MJ/kg||19.3-20.5|
|Ash content, %||0,5-1,5|
(MJ = Megajoules. 3.6 MJ equals 1 kWh.)
The extrusion production technology of briquettes is the process of extrusion screw wastes (straw, sunflower husks, buckwheat, etc.) or finely shredded wood waste (sawdust) under high pressure when heated from 160 to 350 C °. As shown in the table above the quality of such briquets, especially heat content, is much higher comparing with other methods like using piston presses.
Sawdust briquettes have developed over time with two distinct types: those with holes through the centre, and those that are solid. Both types are classified as briquettes but are formed using different techniques. A solid briquette is manufactured using a piston press that compresses sandwiched layers of sawdust together. Briquettes with a hole are produced with a screw press. The hole is from the screw thread passing through the centre, but it also increases the surface area of the log and aids efficient combustion.
Since 2009 in North India biomass briquette consumption has seen new dimensions. Many companies like Nishant Bioenergy and Ekta Bioenergy in Rajasthan are leading in the briquette supply and manufacturing.
Use in China
Throughout China, cylindrical briquettes, called "fēng wō méi" (beehive coal 蜂窩煤 / 蜂窝煤) or "Mei" (coal 煤) or "liàn tàn" (kneaded coal 練炭 / 练炭), are used in purpose-built cookers. The origin of "Mei" is "Rentan" (kneaded coal 練炭) of Japan. Rentan was invented in Japan of the 19th century, and spread in Manchukuo, Korea and China in the first half of the 20th century. There were many Rentan factories in Manchukuo and Pyongyang. Although Rentan went out of use in Japan after the 1970s, it is still popular in China, Korea ("yeon tan" kneaded coal 연탄) and Vietnam ("than" coal).
These are simple, ceramic vessels with metal exteriors. Two types are made: the single, or triple briquette type, the latter holding the briquettes together side by side. These cookers can accommodate a double stack of cylinders. A small fire of tinder is started, upon which the cylinder(s) is placed. When a cylinder is spent, another cylinder is placed on top using special tongs, with the one below igniting it. Swapping spent cylinders for fresh ones, and retaining a still-glowing spent cylinder, the fire can be maintained.
Each cylinder lasts for over an hour. These cookers are used to cook, or simmer, pots of tea eggs, soups, stews, etc. The cylinders are delivered, usually by cart, to businesses, and are very inexpensive.
See also↑Jump back a section
|Wikisource has the text of the 1911 Encyclopædia Britannica article Briquette.|
- How charcoal briquettes are made.
- How easy briquetting biomass, like straw and hay.
- Legacy Foundation - created an appropriate technology briquette maker.
- Holey Briquette Gassifier Stove Development, Richard Stanley, Kobus Venter 14 August 2003 on BioEnergy Lists.
- Briquetting: An Answer to Desertification, Health Problems, Unemployment and Reforestation in Developing Communities - summary of 2003 seminar.