Jan SURÓWKA
Compressed air systems – possibilities of energy efficiency improvement
Ascertained is that compressed air production is very expensive and 1 kW of power created in the compressed air (for the commonly used pressure range of 6-7 bar) takes about 8 kW of compressor consumption. Most often in points of use the compressed air is considered to be practically the “free” energy charger as it is easily accessible and comfortable in use. There are methods and ways to reduce the compressed air production costs in industrial objects and installations, but they need proper approach and knowledge from the users as well as the plant management determination to reduce (or control) the costs. Given are theoretical bases of the air compressing process, elements of its usage and some methods of compressed air systems energy efficiency improvement. Emphasized is the importance of investigating of the compressed air system as a whole (as a set consisting of a motor driven compressor, piping installation, compressed air tanks, fittings and points of use together with delivery control systems) in contradiction to considerations limited to a motor-compressor set only. It is caused by the fact that the biggest potential of energy efficiency improvement lies in a compressor fed system and because the amount of electric energy used in global economy for the needs of compressed air production is very big.
Keywords: energy efficiency, compressed air systems, efficiency improvement of compressed air systems
Andrzej WĘDZIK
Factors determining optimization of cable conductor sizes in a wind farm internal network
Described is the problem concerning optimization of sizes of conductor cables connecting turbines and a wind farm transformer/switching station. Shown are possibilities to use the discrete optimization method with the application of mixed integer programming to solve the problem. Discussed are factors influencing the optimization of cable conductor sizes in a wind farm MV internal network. Presented are analyses helping to answer the question: in what way should we connect turbines to obtain the lowest possible costs? Given are practical conclusions concerning designing of a wind farm internal MV distribution network, resulting from the carried out calculations and analyses. Presented results show that the financial savings (or losses) of the investor can be significant. They depend on many factors such as: assumed service life of a wind farm, cables and energy prices or a discount rate. Practical experience shows that the savings can reach the level of several to even tens of percent.
Keywords: wind farms, wind farm MV internal network, optimization of cable sizes
Ewa KOSSAK
The role of a public sector in the field of energy efficiency in the light of the Directive 2012/27/UE recommendations
Discussed is the public sector role in the field of promotion and accomplishment of a task like energy efficiency. Effective realization of the public sector new duties resulting from the Directive 2012/27/UE and concerning the model role in the field of energy efficiency needs not only the acceptance of a long-term energy efficiency improvement strategy but also the incorporation of this problem into all other national sector policies (e.g. policy of space management, road infrastructure, housing policy etc.). Only the integrated approach to the problem of energy efficiency can be cost efficient and bring the biggest effects in the form of a scale of projects realized in this field. As the previous experience shows, the sole imposition of duties on the public sector does not guarantee the efficient realization of the model role. At the same time, when adequate legal framework is accepted, the activities having in aim dissemination of the non-budget investment financing models in a public sector, for instance using the formula ESCO, EPC or PPP, should be taken up. But for further development of such financing models there will be a need of a strong political back-up, adequate and stable legal and macroeconomic surrounding and, first of all, the public sector willingness to participate in such ventures.
Keywords: UE directives, energy efficiency, public sector role
Krzysztof BILLEWICZ
Digital safety of electric power companies. Can the first defence bridgeheads be easily captured?
The safe cyberspace of electric power companies became an element indispensable for reliable work of a power system that in turn is a condition of ensuring the national energy security. The problem touches very critical aspects – national energy security cannot be endangered only because some employees or software providers do not apply basic digital safety rules. Many people live in a delusive confidence of their resistance to cyber attacks, claiming and thinking that they are too smart to be manipulated, deceived or influenced – they assume that such situations can happen only to the simple-mindeds and fools or in films. Here we can find the simplest methods used by cyber offenders to break the first-line firewalls in a company information system. Ignoring safety rules at work, electric power corporation employees can jeopardize functioning of the whole national power system and, in case anything like that happens, financial losses can be enormous. The attacks can be divided into several groups: physical – if it is a good description of taking actions in a cyberspace, external – i.e. breaking into a company premises, socio-technical ones, equipment and data theft or gaining access to a company network on an inner side of a firewall.
Keywords: electric power companies, company digital security, safe cyberspace
Artur JASIŃSKI
Extended operational time of domestic power units – chances and threats
Delays and stays in realization of big power investments will probably force the need of the existing power units operation for the next 15 years - it means that the majority of 200 MW units will have to cope with operating periods exceeding 350 thousand hours. The progressing ageing process of generating units together with the systematic tightening of the Union pollution emission standards, especially of SO2 and NOx, forces withdrawal from operation or, at least, undergoing a thorough modernization of the old units. Though there is no real alternative to successive extention of domestic power units’ operational period, we should be aware of the weak and strong sides of this problem and properly manage the chances and threats resulting from it. The knowledge of power units’ residual lifetime is necessary for extending their operating possibilities. But the balancing between the existing power units’ extended operational period weak and strong sides is not so easy as we deal with many factors influencing the conclusions, and making decisions concerning the extension of operational period of the already installed units is burdened with many risks and has got quite a number of weak sides.
Keywords: domestic power units, operational period extending possibilities, risks
Michał KWIECIEŃ, Arkadiusz GOŁAWSKI
Creep as the factor limiting a steam piping long-time operation
Holding the high-temperature strength by boiler or pipeline elements in the perspective of a long-time operation is limited by many factors, including creep. As the vast majority of power units in Poland have exceeded the calculated operating-life almost twicely we can expect that this phenomenon will concern the bigger and bigger amount of power equipment elements. Regular carrying out of the diagnostic tests will significantly influence steam pipelines working safety by eliminating the elements endangered by a damage (leak) during work. Analysis has been made of a material cut out from the elbow of a primary steam installation being in operation for about 260 thousand hours where, during periodic testing, decohesive changes were detected. Activities, taken up already at the stage of non-destructive tests, enabled at first to diagnose the dangerous for life and property condition of the pipeline elbow material and then its safe replacement. The later on conducted destructive tests confirmed appropriateness of this decision, as further operation of this pipeline fragment could even lead to the loss of tightness.
Keywords: steam pipelines, diagnostic testing, creep
Antoni LITWINOWICZ
The role of an independent expert at the stage of water preparation technology selection for new investments
As the consequence of a wrong functioning of water and wastewater treatment equipment used in power industry, post-exploitational sediments and corrosion can occur in a part of this equipment that eventually leads to the rise of operating costs and even to the destruction of basic installation elements. Ineffective, often non-optimized work of a sanitary or industrial sewage treatment plant makes a serious financial problem because of excessive charges for environmental pollution. Many operational troubles could already be avoided at the stage of water treatment technology selection for new investments or for water treatment plants undergoing thorough modernization. Presented is an attempt to call the attention to expert activities that should be taken up at the earliest stage of realization of investment projects having in aim construction of a water treatment plant not creating any problems during its operating life neither in a short nor in a long-range time perspective.
Keywords: water and wastewater treatment equipment, water preparation technology selection, independent expert role
Mateusz PALUCH
Problems with management and utilization of wastes left over after chemical cleaning and pickling of appliances in the light of environmental requirements
Beginning from the year 2001, key changes are successively introduced in legal regulations concerning environmental protection, including waste management. After every process of chemical cleaning or pickling of power equipment, we deal with post process chemical solutions which must be treated as wastes. Depending on the type, process complexity level and the size of an object, we receive wastes of various grades of both qualitative and quantitative noxiousness. More and more strict regulations concerning waste management are introduced, that is why the problem of wastes origination during the processes of chemical cleaning and pickling became so important. But if we consider the chemical solutions coming from the process of chemical cleaning and pickling to be by-products, they will automatically lose the status of a waste. It makes dealing with such substances significantly easier as their registering is no longer needed. The best idea of management and, at the same time, reduction of waste quantity is to re-qualify them as by-products, that in turn can be successfully used in some other technological processes.
Keywords: chemical cleaning and pickling of appliances, waste management, re-qualification as by-products
Arkadiusz DYJAKON, Przemysław BUKOWSKI, Bogdan DAMS
Technical and economic analysis of Archimedes’ screw hydropower plants usefulness for low-head application
The necessity to reduce CO2 emission to the atmosphere and realization of energy strategy for Poland until the year 2020 brought about the interest raise in renewable energy sources including the water one. Hydropower potential of Poland, in the context of big dams, is relatively low, but there are many possibilities to develop small hydropower plants. However, because of the hitherto existing technical problems with utilization of low-head dams, this potential has not yet been adequately made use of. Presented is a new solution of a hydropower plant for gentle gradient waters with the application of Archimedes’ screw. Technical and economic analysis is made for a small Archimedes’ screw hydroplant, based on real investment and operational data. Proved is, that such small hydroplant is a very good source of electrical energy and an attachment to the existing power system and can be characterized by economically justified profitability index.
Keywords: hydropower plant, Archimedes’ screw, technical and economic analysis