Pristine-M process technology for drying of low rank coals Aug09

Pristine-M process technology for drying of low rank coals...

Pristine-M process technology for drying of low rank coals Pristine-M process technology for the drying of the low rank coals is being developed by Clean Coal Technologies, Inc. (CCTI). It is a patented technology for converting raw low rank coal into a cleaner burning more efficient fuel. It addresses the need for a low moisture coal which is economical to transport, stable in transportation and does not reabsorb moisture. Pristine-M is a low-cost coal de-watering technology which has succeeded in drying coal and stabilizing it cheaply using volatile matter (VM) released by the feed raw coal. Pristine-M process reduces the moisture content of low-rank coals, while also stabilizing and sealing the treated coals to prevent moisture re-absorptions and spontaneous combustion. The process also increases the calorific value (CV) of the low-rank coals to values which are comparable with the bituminous coals. Pristine-M is the third stage of the development of the process. The other two stages are ‘Pristine-SA’ and ‘Pristine’. Pristine-SA is a development stage technology designed to eliminate 100 % of the VM in the feed raw coal. For achieving stable combustion, Pristine-SA treated coal is to be co-fired with treated biomass or natural gas. The process results into a clean fuel, eliminating the need for emissions scrubbers and the corollary production of toxic flue gas desulphurization (FGD) sludge. Pristine-SA gives a versatile coal product which can be used to produce numerous non-fuel products. CCTI’s legacy technology, ‘Pristine’, is designed to remove moisture and VM, as per the requirements. The factor determining VM reduction is boiler design and the need for a certain amount of VM to remain in the coal to ensure proper burn. The end product is a cleaner burning, dry coal. CCTI’s Pristine-M technology is a patented, low-cost coal dehydration...

Drying Technologies of Lignite Coals Jul20

Drying Technologies of Lignite Coals...

Drying Technologies of Lignite Coals Coals are generally ranked as anthracite, bituminous, sub-bituminous, and lignite, with anthracite being the oldest and lignite the youngest in the age. As coal ages, its moisture content decreases and heating value increases. The lignite coal is often being referred to as brown coal. It is considered to have the lowest rank, lowest carbon (C) content and highest moisture content. Moisture content in lignite coals can be even 60 % or more. Lignite coals are usually shallow buried facilitating its easy open mining. These coals besides high moisture content also have high volatile content and low calorific value (CV) with easy spontaneous ignition. High moisture content is the main restraint for the application of lignite coals. Moisture content of coal causes many difficulties during processing, storage, transport, grinding, and combustion. The high moisture content considerably reduces the CV and combustion efficiency of the coal. It also results into higher heat loss in the exhaust gas. In the combustion of lignite coals, the important part of the energy is consumed to evaporate the moisture inside the coal. The combustion of the high moisture content coal creates several problems such as the additional energy consumption for the moisture evaporation, the insufficient combustion and the additional exhaust discharge etc. Moisture content of the lignite coals can be classified into the following three types. Surface moisture – It is also known as external moisture. The moisture adheres to the surface of coal particulates or in the bigger capillary cavities. It is the moisture, which can be removed by the coal drying in air at ambient temperature (around 25 deg C). It depends on water conditions in deposit. Inherent moisture – It is a naturally combined part of the coal deposit. It is also...