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...

WTA technology for drying of lignite coal Jul27

WTA technology for drying of lignite coal...

WTA technology for drying of lignite coal WTA (Wirbelschicht Trocknung Anlage) technology for drying of lignite coal has been developed by German company RWE Power AG. WTA is the German abbreviation which stands for fluidized-bed drying with internal waste heat utilization. RWE Power AG holds a good number of patents on this technology. The first steam-fluidized bed dryer was developed by RWE as the WTA-1 demonstration plant at Frechen near Cologne, Germany,  with a throughput capacity of 53 tons per hour of raw lignite coal having a grain size of 0 mm to 6 mm and an evaporative capacity of 25 tons per hour. During the 20,000 hours of test operation from 1993 to 1999, the WTA-1 demonstration plant along with the vapour compression system for drier heating (employed for the first time worldwide in lignite coal applications) has proved to work extremely well and reliably. Further theoretical work and an evaluation of the test operation of the WTA-1 plant revealed further potential for the technical and economic process optimization. Several alternatives of development were considered and it was revealed that a reduction of the grain size held most potential for further improvement. In 1999, RWE built a test plant called WTA-2 for the fine grained WTA process directly next to the WTA-1 plant in Frechen. This new plant had a design capacity which was increased in several optimization steps from originally 16.4 tons per hour of raw lignite coal throughput and 8 tons per hour evaporation capacity to a raw coal throughput of 28.7 tons per hour and a water evaporation capacity of 13.1 tons per hour during the total of 8,200 hours of operation of the plant by 2011. Based on the extensive experience from the operation of the WTA-2 plant with...

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...

Production of Ferro-Chrome Jul10

Production of Ferro-Chrome...

Production of Ferro-Chrome Ferro-chrome (Fe-Cr) is an alloy comprised of iron (Fe) and chromium (Cr) used primarily in the production of stainless steel. The ratio in which the two metals (Fe and Cr) are combined can vary, with the proportion of Cr ranging between 50 % and 70 %. Fe-Cr is frequently classified by the ratio of Cr to carbon (C) it contains. The vast majority of Fe-Cr produced is the ‘charge chrome’. It has a lower Cr to C ratio and is most commonly produced for use in stainless steel production. The second largest produced Fe-Cr ferro-alloy is the ‘high carbon Fe-Cr (HC Fe-Cr) which has a higher content of Cr and is being produced from higher grade chromite ore. Other grades of Fe-Cr are ‘medium carbon Fe-Cr’ (MC Fe-Cr) and ‘low carbon Fe-C (LC Fe-Cr). MC Fe-Cr is also known as intermediate carbon Fe-Cr and can contain upto 4 % of carbon. LC Fe-Cr typically has the Cr content of minimum 60 % with C content ranging from 0.03 % to 0.15 %.  However C content in LC Fe-Cr can be upto 1 %. Ferro-chrome (Fe-Cr) alloy is essential for the production of stainless steel and special steels which are widely used and are of high quality, typically characterized by a high corrosion resistance and a low tendency to magnetization. The processing cycle of Fe-Cr involves the chemical reduction of the chromite ore. Smelting of HC Fe-Cr ferro-alloy HC Fe-Cr and charge chrome are normally produced by the conventional smelting process utilizing carbo-thermic reduction of chromite ore (consisting oxides of Cr and Fe) using an electric submerged arc furnace (SAF) or a DC (direct current) open arc electric furnace. In SAF, the energy to the furnace is predominantly supplied in a resistive...

Production of Ferro-Silicon Jun27

Production of Ferro-Silicon...

Production of Ferro-Silicon Ferro-silicon (Fe-Si) is a ferro-alloy having iron (Fe) and silicon (Si) as its main elements. The ferro-alloy normally contains Si in the range of 15 % to 90 %. The usual Si contents in the Fe-Si available in the market are 15 %, 45 %, 65 %, 75 %, and 90 %. The remainder is Fe, with around 2 % of other elements like aluminum (Al) and calcium (Ca). Fe-Si is produced industrially by carbo-thermic reduction of silicon dioxide (SiO2) with carbon (C) in the presence of iron ore, scrap iron, mill scale, or other source of iron. The smelting of Fe-Si is a continuous process carried out in the electric submerged arc furnace (SAF) with the self-baking electrodes. Fe-Si (typical qualities 65%, 75% and 90% silicon) is mainly used during steelmaking and in foundries for the production of C steels, stainless steels as a deoxidizing agent and for the alloying of steel and cast iron. It is also used for the production of silicon steel also called electrical steel. During the production of cast iron, Fe-Si is also used for inoculation of the iron to accelerate graphitization. In arc welding Fe-Si can be found in some electrode coatings. The ideal reduction reaction during the production of Fe-Si silicon is SiO2+2C=Si+2CO. However the real reaction is quite complex due to the different temperature zones inside the SAF. The gas in the hottest zone has a high content of silicon mono oxide (SiO) which is required to be recovered in the outer charge layers if the recovery of Si is to be high. The recovery reactions occur in the outer charge layers where they heat the charge to a very high temperature. The outlet gas form the furnace contains SiO2 which can...

Production of Ferro- Manganese Jun19

Production of Ferro- Manganese...

Production of Ferro- Manganese Ferro-manganese (Fe-Mn) is an important additive used as a deoxidizer in the production of steel. It is a master alloy of iron (Fe) and manganese (Mn) with a minimum Mn content of 65 %, and maximum Mn content of 95 %. It is produced by heating a mixture of the oxides of Mn (MnO2) and iron (Fe2O3) with carbon (C) normally as coke or coal. Fe-Mn in a blast furnace (BF) with considerably higher Mn content than was possible earlier was first produced in 1872 by Lambert Von Pantz. The Fe-Mn produced had 37 % Mn instead of 12 % being obtained earlier. Metallurgical grade Mn ores having Mn content higher than 40 % are usually processed into suitable metallic ferro- alloy forms by pyro-metallurgical processes, which are very similar to the iron pyro-metallurgical processes. In its production process, a mixture of Mn ore, reductant (a form of C) and flux (CaO) are smelted at a temperature which is higher than 1200 deg C to enable reduction reactions and alloy formation. Standard grades of Fe-Mn can be produced either in a BF or in an electric submerged arc furnace (SAF). The electric SAF process, however, is far more flexible than the BF process, in that slags can be further processed to Si-Mn and refined Fe-Mn. The choice of process is also dependent on the relative price of electric power and coke. In a three-phase SAF, the electrodes are buried in the charge material. The raw materials are heated and the Mn oxides pre-reduced by hot carbon mono oxide (CO) gas form the reaction zones deeper in the furnace. The exothermic reactions contribute favourably to the heat required. Efficient production of HC Fe-Mn depends on the degree of pre-reduction which occurs...