Investigation of the Suitability of Serbian Lignites for Burning in CFBC Boilers

Abstract

The results of the detailed investigations of behavior of lignites Kolubara and Kovin, in fluidized bed combustion are presented in the paper. Investigation was carried out due to the interest of the Serbian Electric Power Production Company to use CFBC boilers in the process of refurbishment of old pulverized coal combustion boilers. As a part of a feasibility study for CFBC use in power plants in Serbia, investigation of combustion characteristics of lignites was performed using original methodology introduced many years ago by Laboratory for Thermal Engineering and Energy. Methodology was approved by numerous investigations of more than 20 Yugoslav coals for FBC combustion, with the aim to determine design data for bubbling FBC boilers. The main attention in present investigation was paid to the problem of using methodology developed for bubbling FBC in the conditions present in CFBC boilers. Four samples of Kolubara lignite, with heat capacity from 2.5 to 8.5 MJ/kg, and different ash contents were investigated, and also lignite Kovin in the same range of heat capacity. Investigations were performed in three phases: (1) ultimate and proximate analysis, determination of ash sintering temperature by standard method and in fluidized bed laboratory oven, (2) investigations in laboratory fluidized bed furnace and determination of coal particle fragmentation, burning rate, start-up temperature and self-sulfure-capture and (3) investigation of combustion in pilot-plant in stationary combustion conditions. In conclusion, suitability of results obtained in BFBC conditions is approved, and earlier statement that lignites are suitable for BFBC is confirmed by the statement that lignites are even more suitable for burning in CFBC boilers. Considering differences between combustion and flow conditions in bubbling and circulating FBC boilers, behavior of the lignites in CFBC is discussed in details and optimal regime parameters of the CFBC boilers are determined. The results obtained will be used by Serbian Electric Power Production Company for evaluation of bid for CFBC boiler implementation in refurbishment of old thermal power plants.

Combustion of low grade fractions of Lubnica coal in fluidized bed

“…Considering the size of off-balance reserves of lignite in Serbia, as well as large percentage of non-commercial coals from underground mines (about 60% of flne coal fractions), it is possible to build modem, efficient and environmentally friendly boilers with FBC, for production of energy (heat and electricity) in industry and district heating systems, by combusting coals which cannot be burnt in other boiler types [5], or which cannot be burnt efficiently and meet the required environmental standards [8]. At the same time, it is the way to introduce an energy technology, the intense application of which is expected in the 21 *' century.…”

“…Gas sample passes through the coarse filter (2), which prevents coarser particles to pass further through the line (otherwise, they would cause fouling of gas analyzer cells). The conditioner, apart from the flue gas inlet and prepared gas outlet, avails also with a condensate outlet, through which the condensate from the flue gas is removed (5). The space between the spheres, originating from the geometrical shape, is large enough to let the gas through, while large ash particles are stopped.…”

Belgrade’s Urban Transport CO2 Emissions from an International Perspective

“…Even urban public transport modes that use electricity (trams, trolleys, urban rail; due to extremely high dependency on coal for electricity production) are causing serious negative environmental effects [49,50]. But the most important fact is that due to its extremely high share of regular buses, urban public transport of Belgrade is not as CO 2 -effi cient as it should be (Tables 11 and 12).…”

A realistic EU vision of a lignite-based energy system in transition: Case study of Serbia

“…A study [5], based on the cost benefit analysis of the investment costs (640-704 M€) and operation and maintenance costs (67-69 M€/year) for the implementation of Large Combustion Plant Directive (LCPD) and the Industrial Emissions Directive (IED) in Serbia show very high benefit to cost ratio (27)(28)(29), in particular for the society as a whole, including local external costs [6], without the global externalities. As an alternative to upgrading thermal power plants (TPP) to meet emission limit values of the LCPD/IED, so called opted-out has been preferred option in the case of ageing TPP [7], among other alternatives such as refurbishment e. g. boiler replacement [8], conversion and reuse of the site [9]. According to this option, a retirement plan has been mentioned in [10], but national emission reduction plan still need to be developed by the operator until 31.…”