Electric shock protection in a network with an IT supply system
IT supply system finds use in mining undergrounds, chemical industry and in all places where increased supply safety is needed with a concurrent minimization of fire hazards. It is applied on all aircafts and watercrafts. The issue of an electric shock protection with the use of the IT system requires understanding of application substance and specific nature of the system work.
Keywords: IT supply system, electric shock protection
Wojciech MAJKA, Charles Danny FOSTER, Paweł GAWRON, Krystian RUTKOWSKI
Chemical foam cleaning of steam turbines flow systems without disassembly as the efficient and cost-effective method to maintain high thermo-dynamic performance of turbines susceptible to contamination with impurities transported by steam
In case of this part of energy industry that generates electrical and thermal energy (power stations, CHP stations) as well as the other one that works for the needs of driving processing machinery (chemical plants) one of the most substantial issues are the problems with cleanliness of steam turbines and gas TGs flow systems in the compressor section. Presented here chemical foam cleaning of steam turbines and gas TG sets compressor flow systems is one of the maintenance practises bringing quantifiable benefits in a short time. This method does not require any disassembly (opening) of a turbine thus ensuring significant savings in time and expenses compared with conventional cleaning methods. Shown is the potential of this technology offered in Poland and abroad by Ecol Sp. z o.o. from Rybnik and its subsidiary Ecol North America LLC in Orlando, USA. Over the past few years many steam turbines have been cleaned with the use of the presented method in power plants all over the world. Described is the methodology of conducting the cleaning process supplemented by photographs and examples of implementation.
Keywords: steam turbines, flow systems, chemical foam cleaning, Ecol Sp. z o.o., Ecol North America, LLC
Thanh Nguyen CONG, Paweł GAWRON, Wojciech MAJKA
Technology of active foam chemical cleaning as an alternative to chemical solutions cleaning, hydrodynamic cleaning and cleaning with the use of metal scraper bullets
Build-up of deposite from coolant impurities in turbine condensers and other heat exchangers is the main cause of reduced heat exchanging efficiency and can also be the reason of operational problems connected with corrosion processes occurring under the deposit layer. Gradual growth of deposit thickness that in critical cases may cause clogging of heat exchanger pipes, apart from insulation effect hampering the heat exchange, leads to a significant increase of flow resistance and the accompanying energy losses in coolant transmission. And for very big heat exchangers like turbine condensors of power units, the losses caused by excessive amount of sediments on heat exchanging surfaces can dramatically affect the overall energy generation efficiency. This, in turn, results in necessity to keep the appropriate degree of exchange surfaces cleanliness. The existing technologies of cleaning heat exchange surfaces can be divided into the ones realized on-line like continuous ball cleaning and technologies applied during standstills. But each one of them has also, apart from obvious advantages, characteristic limitations. Search for new technologies based on more economic and effective solutions is the noteworthy course of action.
Keywords: heat exchangers, operating process deposits, technologies for cleaning of heat exchanging surfaces
Standstill maintenance under new guidelines
Outage of some equipment or of the whole power unit, especially the permanent one, is an important problem determining the operational reliability. This reliability significantly decreases when we are dealing with no-maintenance outage. Issues related to the choice of an optimum regime are the subject of numerous studies, standards and guidelines. Some of them consider deep changes that occurred in the power market and connected with it a different operational mode of the main generating equipment. New guidelines are the move away from operation based on steady load in favour of the deep control operation, including the biggest generating units, with continuous changing of a power unit characteristic values. Permanent changes in capacity parameters cause problems connected with maintaining of stable physical and chemical parameters in chemically adjusted cycles. This stability is one of the conditions responsible for corrosion hazard minimization. Characterized are here VGB guidelines PowerTech VGB-R 116
Keywords: power unit, standstill maintenance of equipment, VGB guidelines PowerTech VGB-R 116