Coke Oven Gas, its Characteristics and Safety Requirements...

Coke Oven Gas, its Characteristics and Safety Requirements Coke oven gas (CO gas)  is a byproduct gas produced during the production of metallurgical coke in a byproduct coke oven battery, where metallurgical coal is carbonized by heating it in absence of air. During carbonization the volatile matter in the coal is vaporized and driven off. This volatile matter leaves the coke oven chambers as hot, raw coke oven gas. After leaving the coke oven chambers, the raw coke oven gas is cooled which results in a liquid condensate stream and a gas stream. These two streams are processed  in the byproduct plant to recover byproduct coal chemicals and to condition the raw coke oven gas so that it can be used as a fuel gas. The main emphasis of a modern  byproduct plant is to treat the raw coke oven gas sufficiently so that it can be used as a clean, environmentally friendly fuel. Raw coke oven gas after treatment in the byproduct plant is called clean coke oven gas or simply coke oven gas. The evolved coke oven gas leaves the coke oven chambers at high temperatures approaching 1100 deg C. This hot gas is immediately quenched by direct contact with a spray of aqueous liquor (flushing liquor). The resulting cooled gas is water saturated and has a temperature of around 80 deg C. This gas is collected in the coke oven battery gas collecting main. From the gas collecting main the raw coke oven gas flows into the suction main. The amount of flushing liquor sprayed into the hot gas leaving the oven chambers is far more than is required for cooling, and the remaining unevaporated flushing liquor provides a liquid stream in the gas collecting main that serves to flush away...

Fuel gases used in steel industry...

Fuel gases used in steel industry Fuel gas is a fuel which under ordinary conditions is in the form of gas. Fuel gases are used in steel plants for different applications which include (i) a source of heat (ii) as a reductant and (iii) cutting and welding application. Fuel gases usually used in steel industry are natural gas (NG), liquefied petroleum gas (LPG), acetylene, by product gases (blast furnace gas, coke oven gas and converter gas). Natural gas Natural gas is a gaseous fossil fuel which is extracted from deposits in the earth. It is a mixture of hydro carbons consisting primarily of methane (generally greater than 80 %) but includes varying amounts of other higher alkanes such as ethane, propane and butane etc. It may even contain some small percentage of nitrogen, carbon dioxide and hydrogen sulphide. It is an odorless, colourless, tasteless and non toxic gas. Natural gas is lighter than air and it burns with a clean blue flame when mixed with the requisite amount of air and ignited. It is considered one of the cleanest burning fuels. On burning it produces primarily heat, carbon dioxide and water. Quantities of natural gas are measured in normal cubic meters (corresponding to 0 deg C and I Kg/Sq cm pressure) or standard cubic feet (corresponding to 16 deg C and 14.73 psia pressures). The higher heat value of one cubic meter of natural gas varies from around 9500 Kcal to 10,000 Kcal. Its density is around 0.85 Kg/Cum. The main usage of natural gas in the steel industry is in iron making. For production of direct reduced iron it is reformed to produce reducing gases which are then used for the reduction of iron ore. The main reforming reactions are as follows. 2CH4...

Coke Oven Gas generation and usage Apr10

Coke Oven Gas generation and usage...

Coke Oven Gas generation and usage During the carbonization of coking coal in a coke oven battery for the production of coke, around 25-30% of the coal charged is driven off as effluent gases rich in volatile matter and moisture. This gas is known as coke oven gas (CO gas). In the non recovery or heat recovery coke ovens this gas is burnt in the oven itself and provides the required heat for the carbonization of coal. In case of by product battery, the evolved gas is removed as raw gas and is treated in a byproduct plant to give a clean fuel gas. In the byproduct plant, condensable, corrosive and economically valuable components are removed. During the cycle of coking, the gas is produced during majority of the coking period. The composition and rate of evolution of the CO gas changes during the period and the evolution of CO gas is normally complete by the time the coal charge in the battery reaches 700 deg C. The final yield of clean coke oven gas after treatment in the byproduct plant is around 300 N Cum per ton of dry coal. The yield of gas is dependent upon i) volatile matter in the charge coal and ii) carbonization condition. The density of CO gas at standard temperature and pressure is 0.545 Kg/Cum. The raw CO gas may contain hydrogen and methane, ammonia, carbon monoxide, carbon dioxide, ethane, ethylene, benzene, oxygen and nitrogen, hydrogen sulfide, water vapor, cyclopentadiene, toluene, naphthalene, hydrogen cyanide, cyanogen, and nitric oxide. The typical composition of the main components in the raw coke oven gas is in Tab Tab 1  Typical analysis of Raw coke oven  gas Component Unit Dry basis Actual composition Water saturated at   80 deg. C Water...