Lignite Coal

Lignite Coal Lignite coal is a natural resource which is readily available. It is often referred to as brown coal. It has some special characteristics which make it different from other coals. Lignite coal is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It is considered to be the lowest rank of coal due to its relatively low heat content. It has lowest carbon (C) content amongst all types of coals. It is mined all around the world and is mainly used as a fuel for steam and electric power generation. Since it is not economical to transport lignite coal, it is not traded extensively on the world market when compared with higher grades of coal. Large reserves of lignite coal are available in limited areas of the world. Australia, USA and China have the major reserves of lignite coal. Germany has the largest number of power plants based on the lignite coal. In USA, most of the reserves are located in the North Dakota province while in India, the lignite coal reserves are in Neyveli in Tamil Nadu and in Rajasthan. Around 17 % of the world’s coal reserves are lignite coal. As the world’s oil and gas reserves decline, other sources have become attractive. That is why there is a sustained interest in the use of lignite coal. Coals are classified by rank according to their progressive alteration in the natural metamorphosis from lignite to sub bituminous coal to bituminous coal and to anthracite. Coal rank depends on the volatile matter, fixed carbon, inherent moisture, and oxygen, although no one parameter defines rank. Typically coal rank increases as the amount of fixed carbon increases and the amount of volatile matter decreases. Coal is a complex combination of organic matter and inorganic ash formed over eons from successive layers of fallen vegetation....

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...

Liquefied Petroleum Gas- its Characteristics and Safety Requirements...

Liquefied Petroleum Gas- its Characteristics and Safety Requirements  Liquefied petroleum gas is  a gas used in steel plants as a fuel gas for heating in various furnaces and in flame cutting machines of continuous casting machines. It is popularly known by its  abbreviation or short form which is LPG. LPG is also used for oxy-LPG gas cutting and welding. Sometimes it is used for carburization of steel, flame heating, flame gouging, flame hardening, flame cleaning, and flame straightening. Liquid petroleum gases were discovered in 1912 when Dr. Walter Snelling, an American scientist, realized that these gases could be changed into liquids and stored under moderate pressure. From 1912 and 1920, LP gas uses were developed. The first LPG cook stove was made in 1912, and the first LPG  fueled car was developed in 1913. The LPG industry began sometime shortly before World War 1. At that time, a problem in the natural gas distribution process cropped up. Gradually facilities were built to cool and compress natural gas, and to separate the gases that could be turned into liquids (including propane and butane). LPG was sold commercially by 1920. Like all fossil fuels, LPG is a non renewable source of energy. It is extracted from crude oil and natural gas. It is a safe, clean burning, reliable, high calorific value fuel. The main composition of LPG are hydrocarbons containing three or four carbon atoms. The normal components of LPG thus, are propane (C3H8) and butane (C4H10) (Fig 1). Small concentrations of other hydrocarbons may also be present. Depending on the source of the LPG and how it has been produced, components other than  hydrocarbons may also be present. CAS number of LPG gas is 68476-85-7  while its UN number is 1075. CAS number for propane is...

Converter Gas, its Characteristics and Safety Requirements...

Converter Gas, its Characteristics and Safety Requirements During the process of steel making in the basic oxygen furnace (BOF), significant amount of gases, rich in carbon monoxide content, are generated during the blow time at a temperature of 950 deg C. This gas is termed as converter gas or BOF gas. Converter gas is also known as LD gas. It is a byproduct gas produced during the production of liquid steel in a basic oxygen furnace (converter), where impurities of hot metal are oxidized with oxygen gas. The main constituents of converter gas are carbon mono oxide (CO), carbon di oxide (CO2), oxygen (O2) and nitrogen (N2).  Composition wise it is similar to blast furnace gas but with lesser percentage of nitrogen in it. Converter gas is dust laden at the converter mouth. The dust content is around 100 to 120 g/N cum. The recovered converter gas is cleaned in a venturi scrubber using water, followed by processing in the mist eliminators. The gas is then stored in gas holder for steady supply and cleaned further in the electrostatic precipitators (ESP) and finally fed to the gas distribution system. Wet type of gas cleaning plants have capabilities to reduce the dust content of the gas to a level of 5 mg/N cum. The composition of the gas varies from start to the end of the blow and this is a function of the blow time. In the oxygen rich phase (air ratio= 1) at the beginning and at the end of the blowing period the primary gas is burned completely and no gas is recovered during this period. During CO rich phase (air ratio less than 1) only partial oxidation takes place and a combustible waste gas is formed containing CO, H2, CO2 and...