66 Generating Gas Out Of Coal Coal is a sedimentary raw materia/ of fuel in the form of a rock that occurs as a result of chemica/ and physica/ reactions such as rotting, decomposing, homogenization, ete. of accumulated vegetation in swamps. Elements such as "C", "O", "N", "S", "H" and gases that are formed as an outcome of the combination of these e/ements are naturally inherent to coa/. These gases are Hp (Water vapor), CO, CO2, CH4 (Methane gas), SO2, H2S, H2 and 02. Some of these gases are re/eased in the process of carbonization or expelled from the coa/. These gases are vented in the case of cracks or a permeable condition, and are trapped within the voids inside the coa/ if no such conditions exist. Underground gases within the coa/ can be extracted by either; a. Drilling into the coa/ to reach the trapped gas in the voids. Coal bed methane "CBM" is extracted by means of vertical or horizonta/, specifical/y perpendicular to the face cleat, drilling. b. Underground Coa/ Gasification "UCG" and liquefaction of the coa/ by means of two special dri/1 rigs. Additionally, companies such as SASOL South Africa, Krupp in Germany and Exxonmobil in the US have developed gasification methods of their own simi/ar to coking once the coa/ has been brought to the surface. Coal that has been produced for this purpose is processed using special equipment and catalysts and heated from be/ow in tanks to over 900° Ce/sius to achieve gasification and liquefaction. Various products can be obtained from excavated coa/ by app/ying different processes - biological conversion as seen in the figure below. Gases that occur in coa/ do so as a result of thermogenic and biogenic processes. Scientist have determined that whi/e biogenic gas yielding processes range from Peat to High Vo/atile Bituminous Coal, thermogenic gases take place across the entire carbonization range and reaches a maximum yield /eve/ at the bituminous Of the gases that occur, methane is natura/ gas as we know it, and has an important place in terms of volume in the worldwide natura/ gas production. Today, 300 billion cubic meters of natura/ gas is produced directly from coal beds by means of drilling and this amount is increasing as nations grow more conscious of the issue. ENE RJ I DONYASI EYLOL 2006 Dr. Selami TOPRAK MTA Genel Miidiirliiğü MAT Dairesi Minercıloji-Peırografı Koordincıtörliiğii Bataklıklarda biriken çoğu bitkisel kökenli organik maddeler gömüldükten sonra bir başkalaşım sürecine girerler. Bataklık ortamlarında oluşan turba/ar, gömülme sonrası katılaşmaya başladıklarında ilk önce su buharı ve karbonlu (karbondioksit, karbon monoksit gibi) gazları açığa çıkarırlar. Kömürler daha fazla basınç ve sıcaklık şartlarına maruz kaldıklarında daha sonra, bünyelerinde bulunan metan gazı ve hidrojen gazlarını da açığa çıkarırlar. 1. Kömür, Oluşumu ve Kömürleşme Olayı Kömür, bataklıklarda bitkilerin birikmesi ile ve daha sonra burada değişik (kimyasal ve fiziksel) reaksiyonların (çürüme, parçalanma, homojenleşme v.s.) yer alması ile oluşan bir tortul yakıt hammaddesi ve kayaçtır (Şekil 1). Time Şekil ]. Kömür O/ıışııııııı ve Bıı Değişime {Köıniirleşmeye) Etkiyen Faktörler
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