Experimental simulation of hard coal underground gasiﬁcation for hydrogen production Krzysztof Stan ´ czyk, Krzysztof Kapusta ⇑ , Marian Wiatowski, Jerzy S ´ wia ˛ drowski, Adam Smolin ´ ski, Jan Rogut, Andrzej Kotyrba Główny Instytut Górnictwa (Central Mining Institute), Plac Gwarków 1, 40-166 Katowice, Poland article info Article history: Received 15 March 2010 Received in revised form 9 August 2011 Accepted 10 August 2011 Available online 27 August 2011 Keywords: Underground Coal Gasiﬁcation (UCG) Gasiﬁcation Simulation Hydrogen production abstract The main objective of this study was the assessment of the feasibility of applying the underground hard coal gasiﬁcation in the production of a hydrogen-rich gas. In the course of the experiment the so-called two-stage gasiﬁcation process in which oxygen and steam were supplied to the reaction zone separately in alternate stages was investigated. For this purpose a special surface reactor has been constructed, in which the underground conditions were to be imitated both in respect to the coal seam and the surrounding rock layers. The surface simulation of the underground gasiﬁcation was carried out on extra large coal samples, which allowed the recreation of near real underground conditions. In the reactor an experiment lasting almost 7 days has been performed, with the average hourly gas yields of 7.8 m 3 /h and 9.2 m 3 /h for the oxygen and the steam gasiﬁcation stages, respectively. The average hydrogen concentration during the oxygen stage (heating up) was 15.28% with the maximum of 54.4%. The average hydrogen concentration during the steam stage was 53.77% with the maximum of 62.90%. Thus the fea- sibility of hydrogen-rich gas production in the process of underground gasiﬁcation of hard coal has been demonstrated. During the course of the surface experiment an original and unprecedented database of temperature proﬁles has been acquired which now constitutes an invaluable source of thermodynamic information for the prospective underground gasiﬁcation activities. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Hydrogen is the clean fuel perceived nowadays as the basis for future energy systems as well as constitutes a valuable chemical feedstock for variety of chemical processes and syntheses. The production of liquid fuels by Fischer and Tropsch synthesis, the substitute natural gas (SNG), methanol as well as ammonia can be mentioned here. Despite the fact that hydrogen can be produced applying various methods and from a wide range of feedstock, at present approximately 99% of hydrogen is still produced from fossil fuels – mainly from natural gas in the steam reforming pro- cess. Coal gasiﬁcation is now regarded as the promising way for hydrogen production due to the relatively high global resources of coal and its widespread availability worldwide. The gasiﬁcation techniques have achieved their technical maturity and are com- mercially available, however, compared to other methods of hydrogen production they have a high investment and production cost. In the search for the method to avoid these high costs, differ- ent alternative approaches have been veriﬁed. One of them is the Underground Coal Gasiﬁcation (UCG). Underground Coal Gasiﬁcation is the process of in situ conver- sion of coal deposits to combustible gaseous products. From the chemical and thermodynamic point of view the UCG process runs analogically to gasiﬁcation in the surface reactors. To a certain degree of simpliﬁcation the process can be compared to the Lurgi ﬁxed bed gasiﬁcation. During UCG the carbon contained in the coal seam reacts at elevated temperatures with gasifying agents like air, oxygen, steam or with their mixtures in different ratios [1–4]. The ﬁnal product gas consists of hydrogen, carbon monoxide, carbon dioxide, methane and nitrogen. Composition and heating value of the product gas depends on the thermodynamic conditions of the operation as well as on the composition and temperature of the gasifying agent employed. The UCG process starts with the ignition of the coal seam in the beginning of the so-called gasiﬁcation channel. After the oxidation forehead has been ignited, the supply of the gasiﬁcation agents moves the process forward, along the gasiﬁcation channel towards the production well, where the product gas is collected. The UCG process has a zonal character and the main gasiﬁcation reactions occur both in the solid and the gaseous phases as well as on their boundaries. In the solid phase mainly the pyrolysis and the drying processes take place. Along with the migration of the gaseous product of the thermal decomposition through the pores and slots of the solid phase, 0016-2361/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2011.08.024 ⇑ Corresponding author. Tel.: +48 32 2592753; fax: +48 32 2592267. E-mail address: kkapusta@gig.eu (K. Kapusta). Fuel 91 (2012) 40–50 Contents lists available at SciVerse ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel