Yildiz Kalinci

Exergetic performance assessment of gasification and pyrolysis processes of pre-treated wood board wastes

This paper investigates exergetic performance of gasification and pyrolysis processes and compares their exergy efficiencies, using the experimental data on a two-step process of thermo-chemical conversion of Wood Board (WB) wastes. The exergy values of biomass samples change from 17.49 MJ/kg to 24.57 MJ/kg, respectively. Hydrogen produced from pyrolysis step of gasification varies between 17 (%v/v) and 47 (%v/v) and ranges from 17.1 to 42.6 (%v/v) in pyrolysis. The exergy contents of hydrogen range from 2.20 kJ to 16.26 kJ with the highest efficiency of 93% in pyrolysis step of gasification of WB_1000 samples, and from 2.01 kJ to 10.43 kJ with the highest efficiency of 51% in pyrolysis of WB_250_1000 samples.

Exergetic Performance Assessment of a Binary Geothermal Power Plant

Electricity generation is achieved by means of the medium-temperature geothermal water in the range of 90–140 oC in binary plants with the organic Rankine cycle. So, we investigate a binary geothermal power plant as a case study, from the energy and exergy point of view. Also, exergy destruction rates throughout the plant are quantified and illustrated for comparison purposes. In the plant considered, the brine injection and reinjection temperatures are 140 and 80 oC, with a mass flow rate of 64.87 kg/s, respectively. The energy and exergy efficiencies are calculated as 5.34 and 30.84 %, respectively, based on the heat and exergy input rates to the system at the net power. Furthermore, we examine the effects of some parameters on energy and exergy efficiencies and net power output (e.g., brine injection temperature, brine mass flow rates, turbine inlet temperature and inlet pressure).

5.3 Waste Energy Management

Abstract Today, the world faces growing challenges with waste problems due to the fact that people have moved the problems of the past into the future. What is waste? Is it a problem or a resource? The correct responses to these questions can be found by investigating in more detail the types of wastes and implemented waste management methods. The chapter consists of six main sections. The first section is focused on classification, and explains what waste is and categorizes it according to the producer (e.g., municipal, industrial, and hazardous) and chemical composition (for instance, organic, inorganic and microbiological). The second section presents legislative trends. It is seen that waste management legislation is changing from country to country. Also, it can change over time, because every technological development produces its own new waste. The third section covers waste management methods such as recycling, refuse derived fuel (RDF), landfill, and thermal methods. The landfill method is the oldest and the cheapest one. It is seen that the method will continue in the near future, too, though a lot of legal regulations have been made to reduce its usage. Thermal methods are commonly used in the industrial sector, hence, the thermal methods such as incineration, pyrolysis, and gasification are examined in detail. Considering environmental issues, thermal technology moves toward gasification systems to reduce greenhouse gas emissions as well as production byproducts. The fourth section presents illustrative examples related to using the waste management methods or their combinations. Further, a case study that consists of a circulated fluidized bed gasification (CFBG) system is investigated from the exergy and exergoeconomic points of view. The chapter presents exergy and exergoeconomic analyses in detail. Results of the analyses show that it can produce 1.17 MW e power as well as 0.521 kg/s hydrogen with 3.33

Biomass-based hydrogen production: A review and analysis

/kg cost from 8.5 kg/s biomass waste. Finally, future scenarios of wastes are investigated. Also, to achieve zero waste targets in the future, circular economy and industrial symbiosis concepts are examined and some successful examples from around the world are presented.