TÜRK LİNYİTLERİNİN YERALTINDA KÖMÜR GAZLAŞTIRMA PERFORMANSLARININ STOKİOMETRİK DENGE MODELİ İLE BELİRLENMESİ

Yeraltında kömür gazlaştırma (YKG) işlemi, kömürlerin yeraltındayken işlenmesine olanak sağlayan ve bu yönüyle, geleneksel madencilik yöntemlerine alternatif oluşturan bir kömür işleme prosesidir. Son deneysel çalışmalar ile YKG işleminin, ülkemizde de yüksek miktarda bulunan, düşük kaliteli kömürlere uygulanması durumunda da etkili olduğu ortaya konmuştur. Bu çalışma kapsamında ise, YKG işlemi sonucu üretilen sentez gazın içeriğini tahmin edebilecek bir termodinamik denge modeli oluşturulmuş ve oluşturulan model düşük kalitedeki kömür rezervlerinden üretebilecek sentez gazının özelliklerinin tahmini için kullanılmıştır. Denge modeli, gazlaştırma reaksiyonlarının ve su-gazı dönüşümü reaksiyonunun etkisini dikkate almakta ve kömür kuruması sonucu ortaya çıkan su buharının yapay gaz üzerindeki etkisini belirleyebilmektedir. Oluşturulan denge modeli, literatürde yer alan laboratuvar ölçekli deneysel YKG çalışmasının sonuçları ile doğrulanmıştır. Daha sonrasında ülkemizdeki linyit rezervlerinden YKG işlemi için uygun olduğu belirlenen rezervler, modelde girdi olarak kullanılmış ve rezervler için elde edilen YKG performans çıktıları birbirleriyle karşılaştırılmıştır. Performans analizi için her rezervin oksijen ve buhar ile gazlaştırma çıktıları incelenmiştir. Değerlendirme sonucu yüksek nem ve düşük karbon içeriğine sahip linyitlerin yüksek hidrojen yüzdeli sentez gaz üretimine elverişli olduğu, gazlaştırma ajanı olarak buhar beslemesi yapılması halinde ise tüm rezervlerin hidrojen üretim kapasitelerinin arttırılabileceği belirlenmiştir.

Anahtar Kelimeler:

Yeraltında Kömür Gazlaştırma, Denge Modeli, Linyit

PREDICTION OF UNDERGROUND COAL GASIFICATION PERFORMANCE OF TURKISH LIGNITE RESERVES USING STOICHIOMETRIC EQUILIBRIUM MODEL

Underground coal gasification (UCG) is a coal conversion process that enables the utilization of coal reserves in-situ, and it is an alternative technique to conventional mining methods. Previous experimental studies showed that UCG is a suitable method for the usage of low-rank coal or lignite reserves, which have the major part in the Turkish coal reserves. In this study, a thermochemical equilibrium model of UCG process is developed to predict syngas composition and to compare UCG-performance of the selected lignite reserves in Turkey. The lignite sites are chosen according to the described UCG site selection criteria. The equilibrium model consists of gasification reactions and water-gas shift reaction and it considers the effect of the drying process. The model is validated using the results of the lab-scale experimental UCG study. The predictions are made for both oxygen and steam-gasification processes. Results show that the lignite reserves which have high moisture content but low carbon content are suitable for hydrogen-rich syngas production and hydrogen production capabilities of all reserves can be enhanced significantly by the additional steam supply as the gasification agent.

Keywords:

Underground Coal Gasification, Equilibrium Model, Lignite,

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