Gas formation regularities at the consecutive and simultaneous impact of ionizing radiations and heat on Turkish lignites Islam Mustafayev ⇑ , Fethullah Chichek, Eltaj Yuzbashov Institute of Radiation Problems of Azerbaijan National Academy of Sciences, 31-a H. Javid ave., AZ1143 Baku, Azerbaijan article info Article history: Received 15 February 2009 Received in revised form 25 October 2010 Accepted 27 October 2010 Available online 11 April 2011 Keywords: Lignite Radiation Radiation-thermal Hydrocarbons Activation energy abstract The regularities of formation of gases H 2 , CO and hydrocarbons C 1 –C 4 at the consecutive and simulta- neous inﬂuence of ionizing radiations and heat on Turkish lignites of Karaman–Ermenek deposit was researched. It is shown that at the consecutive inﬂuence of radiation and heat the gas yield depends extremely on the preliminary irradiation dose. The simultaneous inﬂuence of these factors on lignite leads to the gas yield increase which is connected with acceleration of the active radiolytic particles’ dif- fusion and breaking off reactions with their participation. Under the inﬂuence of the accelerated electron beam lignite decomposes with the relatively high radiation-chemical yields than under the inﬂuence of gamma radiation which is connected with acceleration of the diffusion processes due to the irradiated sample’s heating. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Studying of the radiation-chemical transformation of the coaly materials (coal, lignite, bitumen, carbon, etc.) is of great impor- tance for clariﬁcation of application possibility of ionizing radia- tions for synthetic fuels production (synthesis gas, hydrogen, liquid fuel, semi-coke) from the solid fossil fuels, for assessment of the natural radiation contribution to metamorphism and genesis of the fossil fuels, and for determination of radiation stability of the carbonaceous materials. The research of regularities of gas forma- tion from the coaly materials presents information about polycon- densation and destruction processes that are in progress in the irradiated system, as well as about radiation stability of the object. So this issue has been researching during the last 30 years on the carbonaceous materials samples from the USA, Italy, Russia, Azerbaijan, etc. [1–4]. The radiation-chemical transformation of the low-grade Turkish coals was not studied enough; there are sep- arate studies [5] relating to Yataqan and Soma lignites. At the same time acquisition of the systematic data about the radiation-chem- ical transformations has a great importance for their potential assessment to synthetic fuel production, as well as for environ- mental risk assessment of using them. It should be noted that in the composition of Turkish lignites from Yataqan-Muqla deposit the natural radionuclides’ content is high (>10 3 %), and this makes deﬁnite environmental problems when using them. In this paper the investigation results of the gas formation regularities at the consecutive and simultaneous impact of radiation and heat on Turkish lignites from Karaman–Ermenek deposit are adduced. 2. Research technique As the research object, the ground (+0.5/1 mm) and washed lignite samples, which have the following characteristics: content (mass,%) of moisture – 15.6, ash – 19.26, sulfur – 2.01, and caloriﬁc value – Q = 3775 kCal/kg were used. In all cases the samples were undergone preliminary vacuum heat treatment at temperature 105 °C for removal of the adsorbed water and occluded gases. Then they were ﬁlled into ampoules from molybdic glass, with volume 30 ml. We have prepared two sets of ampoules. For the experi- ments carrying out at temperatures below 300 °C mass of the sam- ple was up to 2 g. But in the experiments carrying out at higher temperatures (350–400 °C) mass of the sample in an ampoule was reduced up to 0.2 g for avoiding explosion of ampoules, because the pressure of gaseous products released at higher tem- peratures can considerably exceeds atmospheric pressure. Cer- tainly we took in consideration the fact that rate of gas forming is additive to mass of the initial sample. After ampoules unsolder- ing from the vacuum assembly, they were undergone gamma irra- diation from the source Co-60 with the absorbed dose rate in coals P = 0.76 Gy/s in the temperature-controlled conditions. Heating and constant temperature maintenance of the lignite samples were realized by means of heat controller system. The irradiation tem- perature was changing in the range of 40–400 °C. After the irradi- ation the ampoules were opened in a special cylindrical hermetic 0016-2361/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2010.10.061 ⇑ Corresponding author. Tel.: +994 12 4394113; fax: +994 12 5981301. E-mail address: imustafayev@mail.ru (I. Mustafayev). Fuel 90 (2011) 2555–2559 Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel