Stefan POSTRZEDNIK
Analysis of parameters influencing the energetic usefulness of fuels
One of the main parameters characterizing the real fuels is the contents of fuel ballast (moisture and mineral matter), which is accompanied by combustible (organic) matter of each fuel. The parameter which forms the energy usefulness of fuel is the calorific value of combustible substances. The presence of fuel ballast impacts negatively on the effective heating value of the real fuel, which turns out to be more pronounced in the case of fuels characterized by a lower calorific values of combustible substance, such as biomass. The analysis has allowed to establish a quantitative correlation in terms of energy suitability of various fuels.
Keywords: energy fuels, fuel parameters, energy usefulness of fuels
Andrzej Ł. CHOJNACKI
Analysis of reliability of selected devices in MV/LV substations
The paper presents an analysis of reliability parameters and characteristics of buses, insulators, and cable heads used in MV substations. It specifies average values of recovery periods, emergency stop periods, power supply down time as well as the value of electric power not supplied to clients due to failure. It proposes theoretical distribution of analysed reliability values. It also offers an analysis of seasonality and the causes of failures.
Keywords: reliability, power distribution stations, buses, insulators, cable heads
Krystian Leonard CHRZAN
Punctures of overhead insulators and equipment protective covers caused by contamination of their surfaces
Discussed are damages of various types of insulators resulting from contamination of their surfaces. Indicated are some causes of these damages including the non-uniform voltage distribution and electrical discharges on contaminated surfaces of insulators.
Keywords: overhead insulators, contamination flashovers, damages of porcelain insulators
Jacek MALKO
Back to the bipolar world China vs. the US – opportunities or threats
Compared are plans of China and the USA in the energy area. Both countries have together a 42% share in the global energy demand and they are the biggest hard coal consumers and leading importers of crude oil. They also declare an aggressive renewable energy sources policy within the „energy mix” structure and put much effort into development of wind farms: in 2009 the increase of power in this segment of producers equalled to 13.8 GW for China and 10.0 GW for the USA [2] and the last reports say that China’s wind power value until 2016 will increase up to 90 MW. Attention is paid to the fact that team-working in the area of clean-energy technologies can become the beginning of further cooperation between the two countries.
Keywords: competition China vs the USA, power technologies, renewable energy markets
Andrzej SZTELIGA
French experience in nuclear power industry from the point of view of building nuclear power plants in Poland
Discussed is French experience in nuclear power industry and a reference is made to Polish programs and conditions. Attention is paid to the fact that the fundamental thing is to be granted a „public consent” for the projects concerning implantation of nuclear power engineering. Opinion polls say that majority of the public is in favour of nuclear power industry development, as it is to be only a supplement to the existing power generation structure. It will also help to reduce participation in conventional electricity generation of carriers that are more harmful for the environment (coal, gas and oil) and increase the importance of the remaining energy sources including the renewable ones.
Keywords: nuclear power plants, French nuclear power engineering, nuclear power generation in Polish conditionings
Marcin TROJAN
Heat exchange in a platen superheater with regard to ash fouling
Elaborated is mathematical model of a steam boiler showing the influence of water-wall slagging and superheater ash fouling on a boiler performance. With traditional methods, operators are often not able to detect the critical build-up of deposits on specific heating surfaces of the boiler. The elaborated model can be used as a simulator of processes occurring during a steam boiler work, enabling to monitor the influence of slagging and ash fouling on its performance. Presented is a numerical model of a platen superheater that is modelled as the cross-parallel-flow heat exchanger. The process of heat exchange is modelled basing on the real diagram of a flow superheater, with no simplifying assumptions that it is, for instance, a parallel flow exchanger. The elaborated model will allow to determine temperature distribution for steam, wall and flue gases as well as the distribution inside the wall and in the fouling layer adjacent to external surface of the tubes. Transfer coefficient of a tube
material depends on temperature. Presented is a comparison of computation and measurement results of a platen superheater in a natural circulation boiler.
Keywords: steam boiler, wall slagging in a combustion chamber, mathematical model of a boiler
Janusz LASEK
Oxy-fuel combustion and NOx emission. State of knowledge andresearch perspectives
Emission of nitrogen oxides is current research issue. State of the art about creation and elimination of the NOx in oxy-fuel processes is presented. Particularly, the emphasis is placed on the explanation of some process factors and their influence on NOx emission. Specific conditions typical
for oxy-fuel combustion chambers determine creation and elimination of NOx. Thus, they create new possibilities of NOx emission abatement in comparison to traditional air-fired combustion.
Keywords: nitrogen oxides (NOx), oxy-fuel
Ryszard NOSZCZYK, Jacek TKACZYK
Selected problems with electric power supply to underground mining plants
Discussed are selected problems with electric power supply to underground mining plants on the example of Group II transformers. They work in transformer distribution substations, being a part of internal installations and networks of high and medium voltage, and supply objects, machines and equipment with electric energy. Given are conclusions arising from many years of operation.
Keywords: mining plants, electric power supply to underground mining plants, operation of machines and electromechanical equipment
Krzysztof KAZALSKI, Piotr HRYCKO, Arkadiusz REPCZYŃSKI
Conversion of coal-fired OP-130 boiler into biomass-fired BFB boiler - evaluation of energy and emission effects
Presented is description of OP-130 coal-fired boiler modernization into BFB fluidized-bed boiler that proved successful. Research tests show that during combustion of various types of biomass mixtures it is possible to reach the boiler rating, provided that the stable work of the boiler itself and its auxiliaries is ensured. During tests, two rated parameters of the boiler were reached (pressure and steam temperature) and the reached levels of energy efficiency allow to utilize the biomass chemical energy to a high degree. Emission quantities of pollution to the environment during combustion of the analysed fuels meet the requirements of the Minister of Environment Resolution from 20 December, 2005, concerning emission standards for combustion installations. Conversion of pulverised fuel boilers into fluidized-bed ones is one of the ways to implementation of a large-scale biomass combustion with the maximum use of the existing infrastructure.
Keywords: conversion of an OP-130 coal-fired boiler, BFB fluidized-bed boiler, biomass combustion
Adam KUPCZYK
Transport biofuels used in Poland against a background of international tendencies. International market of transport biofuels
Opening of the Polish market for biofuels from the EU became a beginning of failures in our market fuel sectors. Instead of exporting the biocomponents to the EU, our contry started to import them. At present, the Consortium under the management of biotechnologists from SGGW (Warsaw University of Life Sciences) took up research on biofuels of third generation produced from fast-growing poplars. Presented are data concerning the world production of bioethanol and biodiesel in selected countries in the years 2005-2010.
Keywords: transport biofuels, bioethanol and biodiesel production