lignite is a young type of coal. Lignite is brownish black, has a high moisture content (up to 45 %), and a high suphur content. Lignite is more like soil than a rock and tends to disintegrate when exposed to the weather. Lignite is also called brown coal.
Lignite has a colorific value of less than 5 kw/kg approximately.
Lignite shows traces of plants and is intermediate between bituminous coal and peat. Lignite begins as an accumulation of partially decayed plant material, or peat. Burial by other sediments results in increasing temperature, depending on the local geothermal gradient and tectonic setting, and increasing pressure. This causes compaction of the material and loss of some of the water and volatile matter (primarily methane and carbon dioxide).
This process, called coalification, concentrates the carbon content, and thus the heat content, of the material. Deeper burial and the passage of time result in further expulsion of moisture and volatile matter, eventually transforming the material into higher rank coals such as sub bituminous, bituminous and anthracite coal. Lignite deposits are typically younger than higher-ranked coals, with the majority of them having formed during the Tertiary period.
Sometimes called “brown coal,” lignite is the lowest quality and most crumbly coal. This softer and geologically “younger” coal sits relatively close to the earth’s surface.
Lignite can be broken down chemically through coal gasification, the process of producing syngas from coal along with water, air and/or oxygen.
This creates synthetic natural gas that delivers more power and is easier to operate in commercial scale electric generations.
Because of its low energy density and typically high moisture content, brown coal is inefficient to transport and is not traded extensively on the world market compared with higher coal grades.
It is often burned in power stations near the mines, primarily because of latent high moisture content and low energy density of brown coal.
Draig's Advanced Thermal Technology
Firstly, the lignite, which has a water content of more than 50%, is dried to a residual water content of some 12%. In the gasifier, it is subsequently converted at high temperatures with a limited amount of oxygen, so that, instead of the lignite being burnt, a gas compound known as "synthesis gas" is formed. The main components of the gas compound are hydrogen and carbon monoxide. The next step is gas treatment, after cleaning the gas, the desired product, e.g. methanol, ammonia, naphtha (starting material for the production of plastics, for instance), or methane (main component of natural gas). Other useful products of the pyrolysis process consist of is tar oil, which is a substitute for furnace oil and Char which can be used as a domestic fuel or fertiliser production or simply sequestered to prevent the release of Carbon gases to the atmosphere.
Draig has decades of experience in these two technologies (drying and gasification). Despite this process being designed for lignite as a starting material, it is flexible and can also utilise renewables to the degree that they are available. Biomass, for instance, can be used in conjunction with lignite in the gasifier. And by means of gas conditioning, the synthesis gas can be fed back into the Draig burner to raise the gas temeperature for use in Draig's revolutionary air turbine to make electricity. Alternatively the Syngas can be stored for use in another process.
Draig's Community Power Station can pyrolyse lignite, using the syngas to make electricity.
The DRAIG Energy Centre is designed to operate in a community setting, providing electricity, whilst at the same time supporting development within the local community.
Lignite is readily available in many areas of Africa and Draig have many years experience of gasification of solid fuels.
The modern computer based design of the DRAIG Energy Centre means that it requires unskilled personnel to operate the power station.
DRAIG require little water for steam production, Draig Energy Centres can be located in areas where there is no water, such as deserts. No other power station offers this flexibility.
Anthracite, Bituminous coal, Lignites and peat, Wood and wood chips, Bio-fuels, waste derived fuels. In fact if it burns - DRAIG can make electricity from it.
DRAIG have been providing combustion equipment and burner solutions across the World since 1951. The basic principles have remained the same whilst the designs have been modernised to deal with 21st Century fuel source requirements. Modern solutions to modern problems.
Growing Bamboo around each power station provides hundreds of new employment opportunities in each area.
