Mustafa Tahir Akkoyunlu

Determination of economic upper limit of drying processes in coal-fired power plants

ABSTRACT In this study, the economic assessment of coal drying prior to ga rinding mill process in coal-fired thermal power plants was carried out. In the literature, despite the fact that there are studies regarding drying systems, the advantages and disadvantages of these systems in comparison to each other and the benefits that drying will provide, and the economic factors that are the most important determinants in the practice of the drying system, were not adequately analyzed. In this study, on the other hand, a model was developed to determine the necessary critical cost point in order to identify the appropriate drying system. Through the use of this model, the benefits to be gained from the planned drying system and the financial upper limit required for this investment can be specified. As a model application, eight of the thermal power plants in Turkey were examined. The economic upper limit of a drying system to enable coal to be dried at a rate of 10% was determined through a model study carried out for Catalagzi Power Plant.

Effects of Bed Height and Particle Size on Drying of a Turkish Lignite

Drying of coarse lignite particles, because of high inherent moisture content, is very important for the lignite user. An effective drying process is necessary to utilize coarse lignite particles effectively. Fixed-bed drying experiments were carried out for a Turkish lignite (Konya-Ilgın). Effects of bed height and particle size were investigated. Drying experiments were carried out at 80, 130, and 150 mm bed heights and 20, 35, and 50 mm particle sizes. It was found that increasing the bed height increased the drying time and decreased the drying rate, and particles of larger sizes have lower drying rates and higher drying times. Additionally, it was also found that Konya-Ilgın lignite does not show a constant drying rate and has a long falling drying rate. As a result of this study, drying characteristics of Konya-Ilgın lignite were presented for different drying conditions.

Evaporative Drying of Low-Rank Coal

Low-rank coals including the brown and the subbituminous coals are commonly known to contain high moisture content (up to 65%, wet basis), which limits their utilization around the world in spite of their low cost. Today, the most of the drying technolo‐ gies are based on the evaporation of the water from the moist product. In this chapter, the most effective parameters on the evaporative coal-drying process are investigated with the data in the recent literature. The effective parameters are evaluated in three categories as follows: (1) the parameters about the drying media (the type of the media, the temperature, the pressure, the velocity and the relative humidity), (2) the coal parameters (the type of the coal and the size) and (3) the drying method.

A new empirical correlation to model drying characteristics of low rank coals

In the present study, drying of Konya-Ilgn lignite (a Turkish lignite) was modelled by using thin-layer drying models from the literature and a new empirical model. The required experimental works were carried out at different experimental conditions in a fixed bed dryer. The experimental conditions were 0.4 m/s, 0.7 m/s and 1.1 m/s drying air velocities, 70°C, 100°C and 130°C drying air temperatures, 20 mm, 35 mm and 50 mm particle sizes and 80 mm, 130 mm and 150 mm bed heights. The performance of thin-layer drying models was evaluated by a statistical method. The results showed that the proposed model achieves better results than thin-layer drying models in the literature. Therefore, the proposed empirical model may be used to represent drying characteristics of any material. [Received: June 16, 2016; Accepted: December 7, 2016]

Determination of Effective Parameters for Coal Moisture Content Determination Using a ‘Design of Experiment’ Method

ABSTRACT Drying of low rank coal is a very significant topic due to its high economic value. One of the most important parameter in the designing of a dryer is the exiting moisture content of the material at the specified conditions and time. Aim of this study was to utilize the design of experiment methodology to determine the most effective parameters on the moisture content of the dried coal. The investigated parameters were dryer bed height, coal particle size, inlet drying air velocity, inlet drying air temperature, inlet drying air relative humidity, exit drying air relative humidity, and time. The results showed that bed height and time were the most effective parameters, and inlet air relative humidity and inlet drying air velocity were less effective parameters. Additionally, particle size and inlet drying air temperature parameters were also significant. To attain more accurate results in the prediction of the exiting coal moisture content, only more influential parameters may be used. Therefore, the design of experiment methodology was a significant way of determining the effective parameters in the coal drying process.

Evaluation of wind energy potential in a university campus

Today, zero energy campus concept is a popular topic. Zero energy attempts are important for reducing global warming effect and greenhouse gas emissions. In the current study, wind characteristics and wind energy potential of Yildiz Technical University Davupasa Campus were investigated. Data from wind measurement station (10 m height) in campus area was examined. Due to the gaps in the measured data, one year long data was lumped by using all the measured data (25 months). The lumped data was used in all energy analyses. Mean wind speed was calculated as 3.45 m/s at 10 m and north northeast (30°) was defined as prevailing wind direction. Annual wind energy production and capacity factor for Fuhrlander FL 30 (30 kW-27 m hub height) wind turbine were estimated as 28.87 MWh and 10.9%, respectively. According to these results, an economically feasible wind energy project seems not possible. However, a possible wind energy project in Davutpasa campus will help to raise awareness of people. Therefore, it will help and promote to catch the aimed future wind energy capacity of Turkey.

Fragmentation of a Turkish Low Rank Coal During Fixed-bed Evaporative Drying Process

In the present study, a new approach was utilized to investigate the fragmentation of low rank coal during the thermal drying process. Drying experiments were conducted at different drying air temp...

Performance Analysis of Supercritical Binary Geothermal Power Plants

It is possible to generate electricity by utilizing medium-temperature geothermal sources in various closed cycles. These geothermal power plants are very important and valuable as they utilize the sources which have low exergy. In recent years, medium-temperature sources that are around 150°C are used widely for electricity generation. In this study, performance of a supercritical binary power plant, that uses such a geothermal source, is analyzed to find the optimum turbine inlet pressure that maximizes power generation. In this power plant different working fluids are analyzed to find the appropriate fluid that maximizes power generation and efficiency. The observed working fluids are R134a, isobutane, R404a, n-Butane, and R152a. The performance of the plant is calculated with these fluids separately and it is found that the best fluid for performance is R152a for pure fluid and R404a for mixture fluid.