FBC utilization prospects in decentralized cogeneration units in Caucasus region countries

Great differences are encountered among Caucasus region countries with respect to energy resources reserves and economic conditions. Thermal power plants consist of obsolete and inefficient units, while the Soviet-type large heating systems in the area collapsed after 1992 and their reconstruction is considered uneconomic. Renovation needs of the power and heat sector, and the potential of Fluidised Bed Combustion implementations in decentralized cogeneration units were investigated, since operating oil and gas power plants exhibit high fuel consumption, low efficiency and poor environmental performance. Results showed significant prospects of Fluidised Bed Combustion utilization in decentralized cogeneration units in the Caucausus region heat and power sector. Their introduction constitutes an economically attractive way to cover power and heat demands and promotes utilization of domestic energy resources in all of three countries, provided that financial difficulties could be confronted

HIGH ACTIVITY CARBON SORBENTS FOR MERCURY CAPTURE by

High ef fi ciency ac ti vated car bons have been pre pared for re mov ing mer-cury from gas streams. Start ing ma te ri als used were pe tro leum coke, lig-nite, char coal and ol ive seed waste, and were chem i cally ac ti vated with KOH. Pro duced adsorbents were pri mar ily char ac ter ized for their po ros ity by N2 ad sorp tion at 77 K. Their mer cury re ten tion ca pac ity was char ac ter-ized based on the break through curves. Com pared with typ i cal com mer cial car bons, they have ex hib ited con sid er ably en hanced mer cury ad sorp tion ca pac ity. An at tempt has been made to cor re late mer cury en trap ment and pore struc ture. It has been shown that phys i cal sur face area is in creased dur ing ac ti va tion in con trast to the mer cury ad sorp tion ca pac ity that ini-tially in creases and tends to de crease at lat ter stages. Desorption of ac tive sites may be re spon si ble for this be hav iour. Key words: activated carbons, KOH activation, surface area, pore volumes, mercury adsorptio

High activity carbon sorbents for mercury capture

High efficiency activated carbons have been prepared for removing mercury from gas streams. Starting materials used were petroleum coke, lignite, charcoal and olive seed waste, and were chemically activated with KOH. Produced adsorbents were primarily characterized for their porosity by N2 adsorption at 77 K. Their mercury retention capacity was characterized based on the breakthrough curves. Compared with typical commercial carbons, they have exhibited considerably enhanced mercury adsorption capacity. An attempt has been made to correlate mercury entrapment and pore structure. It has been shown that physical surface area is increased during activation in contrast to the mercury adsorption capacity that initially increases and tends to decrease at latter stages. Desorption of active sites may be responsible for this behavior

Fluidized bed combustion with the use of Greek solid fuels

The paper is an overview of the results obtained up to date from the combustion and co-combustion activities with Greek brown coal in different installations, both in semi-industrial and laboratory scale. Combustion tests with Greek lignite were realized in three different Circulating Fluidized Bed Combustion (CFBC) facilities. Low rank lignite was burned in a pilot scale facility of approx. 100kW thermal capacity, located in Athens (NTUA) and a semi-industrial scale of 1.2 MW thermal capacity, located at RWE's power station Niederaussem in Germany. Co-combustion tests with Greek xylitic lignite and waste wood were carried out in the 1 MWth CFBC installation of AE&E, in Austria. Lab-scale co-combustion tests of Greek pre-dried lignite with biomass were accomplished in a bubbling fluidized bed in order to investigate ash melting problems. The obtained results of all aforementioned activities showed that fluidized bed is the appropriate combustion technology to efficiently exploit the low quality Greek brown coal either alone or in conjunction with biomass species

REMOVAL OF POLLUTANTS FROM POOR QUALITY COALS BY PYROLYSIS by

Com bus tion of poor qual ity coals and wastes is used to day world wide for en ergy pro duc tion. How ever, this en tails sig nif i cant en vi ron men tal risks due to the pres ence of pol lut ing com pounds in them, i. e. S, N, Hg, and Cl. In the com plex en vi ron ment of com bus tion these sub stances are form ing con-ven tional (i. e. SOx, NOx) and toxic (PCDD/Fs) pol lut ants, while, the highly toxic Hg is vo lati lised in the gas phase mainly as el e men tal mer cury. Aim ing to meet the re cently adopted strict en vi ron men tal stan dards, and the need of af ford able in cost clean power pro duc tion, a pre ven tive fu els pre-treat ment tech nique, based on low tem per a ture car bon iza tion, has been tested. Clean coals were pro duced from two poor qual ity Greek coals (Ptolemais and Meg a lop o lis) and an Aus tra lian coal sam ple, in a lab-scale fixed bed re ac-tor un der he lium at mo sphere and am bi ent pres sure. The ef fect of car bon iza-tion tem per a ture (200-900 °C) and res i dence time (5-120 min utes) on the prop er ties of the chars, ob tained af ter py rol y sis, was in ves ti gated. Spe cial at ten tion was paid to the re moval of pol lut ants such as S, N, Hg, and Cl. T