Determination of drying characteristic of Konya-Ilgın lignite

Gasification, liquifaction and drying of low rank coals are still up-to-date topics around the world. The main aim of the studies, concerning the literature, is to be able to utilize low rank coal sources more efficiently. Turkey is a foreign-dependent country in energy sector. Therefore, utilizing of lignite sources, which is the most important local energy source of Turkey, efficiently is a very important topic for Turkey. Additionally, attention to the local energy sources has increased due to important parameters in energy strategies of countries such as share of energy import in total current deficit, international fluctuations in cost of energy, security of energy supply, etc. Problems in efficiency, operation and emissions are seen in utilization of high moisture content local coals in both electricity production and heating sectors. Main cause of the problems is to consume significant part of the energy for removal of moisture. However, there are hardly ever studies for increasing the quality of local lignites and removing of high moisture content which is the basic cause of operation problems. It can be seen that there is a high interest on fluidized bed technology in the literature. However, there are some other different technologies investigated due to numbers of effective parameters on drying process, energy consumptions, coal particle sizes, high capacity drying demands and differences in coal properties. Therefore, there are lots of studies on superheated steam fluidized bed technology in the recent years. In Turkey, there is no any applicable study, although there are a few studies on coal drying. This is a significant deficiency for Turkey in which lignite is the most important local energy source. The main aim of this thesis is to do necessary experimental and theoretical works to make suitable of liginites used in heating sector according to regulations. Drying characteristics of Konya-Ilgın lignite in a fixed bed dryer experimental set-up have been determined within the context of this thesis. Most effective parameters as drying temperature, drying fluid velocity, bed height and particle size, have been investigated by the experimental set-up. Drying experiments have been done with coarse lignite particles, which is different from most of the studies (0-6 mm) in the coal drying literature. This is due to the regulations which state that size of coal particles should be course (18-150 mm). This limitation affects the particle size and drying method. Drying experiments have been carried out at 70, 100 and 130 oC drying air temperatures, 0.4, 0.7 and 1.1 m/s drying air velocities, 80, 130 and 150 mm sample heights and 20, 35 and 50 mm sample sizes. The results of this thesis show that drying air temperature and velocity, sample size and bed height all significantly influence the drying process. Drying time is reduced by increasing of the air temperature and velocity and decreasing of the particle size and bed height. Drying of Konya-Ilgın Lignite doesn't show a constant drying rate stage. It has long and falling drying rate stage. The necessary knowledge has been created to optimize dryer sizes and costs for preferred output moisture and necessary drying time by using the obtained results from this study. The necessary studies have been carried out for appropriate dryer design after determination of drying characteristics of Konya-Ilgın lignite. Many different experimental conditions have been examined to achieve dryer output properties as in the regulations. The aim of these experiments is to obtain required heating value, fragmentation rate, and moisture content value. It is determined that the most appropriate drying method is band dryer due to the particle sizes. For this aim, required design parameters have been determined for band dryer system. As a result, pre-design of 1 ton/h capacity band dryer has been performed.