Coldry technology for low rank coal drying Aug19

Coldry technology for low rank coal drying...

Coldry technology for low rank coal drying Coldry technology is being developed by Environmental Clean Technologies (ECT) Limited, Australia. The technology consists of expelling of water from a wide range of low rank coals (lignite coals and sub-bituminous coals) containing up to 70 % moisture into high calorific value (CV) black coal equivalent (BCE) pellets with a moisture content of around 10 %. The BCE means that the net energy value of the Coldry pellets is similar in range to that of many black coals. Coldry technology is a patented process which changes the naturally porous form of low rank coals to produce a dry and dense pellets by a process which is called as ‘brown coal densification’(BCD). The technology is based on research initially conducted by CRA and University of Melbourne in the early 1980s. The technology has been demonstrated at pilot plant scale at Bacchus Marsh Coldry plant. This plant was commissioned in 2004, enhanced with a water recovery system in 2007, and upgraded in 2011 so that it can produce up to 20,000 tons per annum of Coldry BCE pellets. The process has been tested and proven successful on a wide range of low rank coals. Principle of the process The Coldry process combines two unique aspects namely (i) brown coal densification, and (ii) waste heat utilization. The process stimulates a natural chemical reaction within the coal. This reaction polymerizes active sites in the coal compounds and expels chemically bound water. The polymerization of the active sites collapses the coal pore structure and expels the physically trapped water. The ejected water migrates to the surface of the coal pellets. The surface water is evaporated by the utilization of waste heat from an adjacent power plant (PP). BCD is a natural phenomenon whereby the physical structure...

Energy Management in Small and Medium sized Re-rolling mills...

Energy Management in Small and Medium sized Re-rolling mills Energy consumption in small and medium sized re-rolling mills takes place in two forms namely (i) electrical energy, and (ii) fuel or heat energy. Electrical energy is used directly in main rolling process for shaping of hot billets into rolled product (rolling mill, and shears etc.), in reheating furnace (coal pulverizer, blower, and pusher etc.) and also in auxiliary (roll turning machines, pumps, man coolers, overhead crane etc.), and shop lighting. Fuel energy is used in the reheating furnace for raising the temperature of the feed material to desired temperatures (generally 1150 deg C–1250 deg C). The division of the energy in these two forms normally varies from mill to mill based on the practices employed as well facilities installed in the re-rolling mills in SME (small and medium enterprise) sector. However, the share of electrical energy in small and medium sized mill generally varies in the range 20 % to 30 %. Consumption of fuel energy takes the major share of the energy consumption and usually constitutes 70 % to 80 %. From a theoretical perspective, the energy in hot rolling is primarily determined by the requirements of reheating of feed material. The theoretical energy for deformation is only 0.02 GJ/ton (around 5000 kcal/ton), compared to 0.83 GJ/ton (around 200,000 kcal /ton) for heating billets when charged cold in the reheating furnace. Though it is not technically feasible to achieve theoretical energy consumption figures, but the energy efficiency of the rolling mill is depends upon how close it is to the theoretical consumption. Management of electrical energy consumption Out of the total electrical energy consumed by a re-rolling mill, the share of the process of rolling is in the range of around 60 %...

Non Coking Coal for Iron Production...

Non Coking Coal for Iron Production A non-coking coal is that coal which when heated in the absence of air leaves a coherent residue. This residue does not possess the physical and chemical properties of the coke and is not suitable for the manufacture of coke. Non coking coal like any other coal is an organic rock (as opposed to most other rocks in the earth’s crust, such as clays and sandstone, which are inorganic). It contains mostly carbon (C), but it also has hydrogen (H2), oxygen (O2), sulphur (S) and nitrogen (N2), as well as some inorganic constituents which are known as ash (minerals) and water (H2O). Coal was formed from prehistoric plants, in marshy environments, some tens or hundreds of millions of years ago. The presence of water restricted the supply of oxygen and allowed thermal and bacterial decomposition of plant material to take place, instead of the completion of the carbon cycle. Under these conditions of anaerobic decay, in the so-called biochemical stage of coal formation, a carbon-rich material called ‘peat’ was formed. In the subsequent geochemical stage, the different time-temperature histories led to the formations of coal of widely differing properties. These formations of coal are lignite (65 % to 72 % carbon), sub-bituminous coal (72 % to 76 % carbon), bituminous coal (76 % to 90 % carbon), and anthracite (90 % to 95 %) carbon. The degree of change undergone by a coal as it matures from peat to anthracite is known as coalification. Coalification has an important bearing on the physical and chemical properties of coal and is referred to as the ‘rank’ of the coal. Ranking is determined by the degree of transformation of the original plant material to carbon. The ranks of coals, from those with...