Herbert Leopold GABRYŚ
Power industry in Poland ...in the middle of the year
On the basis of statistical data presented is condition of the Polish power industry in the middle of the year 2016. Attention is paid not only to the economic aspect and activity effects but also to technical wear out of machines and equipment in the sub-sector of electric energy generation. Indicated is, among the others, a substantial and still growing share of material fatigue as one of unit failure causes. Defined is the “decalogue” of questions that should be answered in the updated energy doctrine of the Polish state.
Keywords: power industry and coal mining in Poland, assessment of sector situation, necessary changes
Marek CHMIELEWSKI, Leszek PIOTROWSKI, Bolesław AUGUSTYNIAK
Procedure of residual stresses quick evaluation with the use of circulating alternate magnetic field probe – in the case of magnetically welded anisotropic steel
Presented is as complete description as possible of a measuring device dedicated for quick evaluation of residual stresses occurring in steel constructional elements. Functioning of the device is illustrated by results of stress measurements conducted in a butt welded joint. State of stresses was determined using results of Barkhausen effect (BE) angular distribution intensity measurements. The innovative technical solution in such measurements is the application of an BE four-pole probe that magnetizes the tested element with alternating magnetic field of abruptly changing direction. Measurement time of one angular distribution equals about 30 seconds. The probe can also examine curved surfaces. The proposed procedure of determining stresses using results of BE angular distribution assumes carrying out of some relatively simple software aided operations. BE intensity angular distributions are then converted into strains angular distribution and the conversion is based on the so-called inverse calibration functions.
Keywords: steel constructions, measurements, residual stresses
Stefan GIERLOTKA
Impact of an electric current on a human body
Discussed is the course, parameters and results of the impact of electric current – DC and AC – on a human’s body. Attention is turned to the fact that an electric current flowing through a human’s body generates heat, whose value is proportional to the shock current squared, time of its flow and tissue impedance. The biggest thermal tissue damages occur in the area of a surface where a body touches the electrode. During a shock on a large touch surface there can occur dangerous shock results even if the current density is not high. The thermally damaged tissue is usually seen in the form of changed colour – from reddish to charred. The flow of a shock current of density up to 10 mA /mm2 does not result in any skin changes. Sometimes under the electrode there can be seen a fragment of epidermis in grey and white colours and of a rough surface. When the shock current density is higher than 10 mA/mm2 then a low skin elevation can be observed near the rim of the electrode. Shock current density higher than 32 mA/mm2 causes electric puncture of the epidermis – one can then observe grey and white spot marks on the skin. After a longer exposure to the current a red swelling forms on the skin. A flow higher than 50 mA/mm2 causes, nearby the place where the body touches the electrode, forming of brown patches that change into blisters. The current density of more than 70 mA/mm2 causes skin charring. Extensive burns caused by an electric arc often lead to systemic disturbances called the “burn shock”. Occurrence of the shock depends on the extent of the burn, but the burn involving 70% of the body is the deadly one. The factor that causes burn shock occurrence is the loss of plasma as a result of fluid collection in burn blisters. The shock is the result of a sudden reduction of the blood supply to tissues that in turn causes their anoxia. An electric arc, because of its thermal impact, is dangerous for eyes and face – high luminance causes photofobia and conjunctivitis. In reports of electricians that suffered an electric arc shock one can find a description of a “light ball” – such phenomenon is called an “electricians’ moon”.
Keywords: electric current impact on a human body, electric paramaters of a human body, electric shock results
Michał KOWALIK
Reduction of losses and CO2 emission in a power plant by approx. 35%
Discussed are possibilities of application in thermal power plant systems of heat pumps transferring the energy collected in a low temperature (e.g. in a refrigerator inside) to the place where it can be given back at a higher temperature (e.g. kitchen heating). Application of a heat pump for a power plant condenser cooling water and using it as a replacement (partially or wholly) to an atmospheric/fan cooling tower, enables achieving of the cooling water stable temperature on a level ensuring the best possible functioning of the condenser.
Keywords: condensers in thermal power plants, recovery of cooling losses, improvement of thermal power plants efficiency
Elżbieta BOEHME-ŚLIWA, Stanisław JAGUSTYN
Experience from commissioning of the demineralization plant in Fortum Silesia S.A. – CHP Zabrze
Regarding economic and environmental reasons as well as development of modern technologies used for preparing water to the make-up of water/steam cycle and heating network loss, in February 2014 Fortum Zabrze S.A. announced a tender for the main contracter of „Modernization of Demineralization Station”. The main objective of this investment was to replace the existing, time - worn preparation stadion operating on the basis of ion exchange technology. This paper presents experience gained during the investment execution process together with post investment measurement of the water demineralization station.
Keywords: DEMINI water demineralization station, Fortum Silesia S.A.
Przemysław SYTY, Adrian SOBCZYSZYN
Corrosion damages of austenitic superheater tubes in a biomass-fired boiler
Current needs for using renewable energy sources enforce wider application of biomass fuels in power boilers. It generates a problem connected with a higher share of aggressive chlorine compounds and the need to install systems reducing this share in flue gases. An additional presence of sulfur, potassium and sodium compounds together with a high steam superheaters operation temperature intensifies the chemical corrosion process. Given is an example of a negative influence of the above described problem on a III° superheater pipe coils made of TP310 austenitic stainless steel working in a biomass BFB boiler.
Keywords: biomass combustion in power boilers, superheater tubes damages, chemical corrosion
Przemysław JURASZ
Chemical cleaning of power plant equipment, increase of the needs and execution limitations, in the a long time operated power units
Chemical cleaning of a power equipment is a necessary operation during its working life. Cleanliness of inner heating surfaces has direct influence on efficiency that results in operational costs. Keeping inner heating surfaces clean is a guarantee of an equipment availability and postpones the possibility of a malfunction. No one should be afraid of an equipment chemical cleaning and the balance between possible dangers connected with the process of cleaning and the process effects is definitely positive.
Keywords: Polish power equipment, operational costs, equipment chemical cleaning
Wojciech BRUNNÉ
Removal of stress concentration sources in piping critical elements through construction changes
Described are cases of stress additional concentrations (above the acceptable level) caused by a sub-optimal design process. The discussed cases are grouped according to the three main aspects: inappropriate selection of attachments and/or of the whole system, incorrect selection of a pipeline route, incorrect selection of both – attachments and a route. Shown is also how to remove the additional stress source. Presented examples are taken from the already realized by Pro Novum Sp. z o.o. projects performed for industrial and commercial power plants during the last twenty years.
Keywords: pipelines critical elements, stress concentrations, construction changes