Rising consumption of global energy, stricter environmental requirements and rising costs are the causes for increasing pressure from countries on companies to become more energy efficient in resource management. As a result, energy management is becoming an increasingly important task within companies, with the aim of reducing costs, meeting legal requirements and improving the image of the company. All this has created the need for a global standard for energy management. In the master's thesis we will present the international standard "ISO 50001: Energy management system" developed by the International Organization for Standardization (ISO) in order to provide guidelines to organizations for managing and improving energy efficiency. The standard is based on a continuous improvement cycle of plan – do – check – act and is taken from other known management systems such as ISO 14001 Environmental management systems and ISO 9001 Quality management systems.
The purpose of the master's thesis is to show a comprehensive approach for energy efficiency that can be set by a company or organizations of all sizes. It starts with the introduction of energy policy within the company and continues with the analysis of industrial processes and the search for possible improvements. We illustrated this procedure with a practical example, where we wanted to show the difference in energy efficiency of older, used equipment compared to new, more efficient equipment.
In the thesis we presented the company Cinkarna Celje, which allowed me to use the pump test room, where we performed the practical part of the task. We have shown how the company manages energy and their use of energy over the years. In the following two chapters, I described the structure and basic operation of the centrifugal pump, asynchronous motor and frequency converter. These devices as a whole make up the pumping system that we used in the pump test room. In order to achieve greater efficiency of the existing pumping system, the chapter also covers the efficiency improvement process, which follows in seven steps. This process, which is written in the form of instructions, brings us closer to the process of how to identify any possible improvements that are aimed at increasing the efficiency of the equipment or system and thereby reducing operating costs.
The practical part of the task took place in the pump test room, where we carried out tests on two different examples. We tested an older pump powered by an older asynchronous motor with an energy efficiency of IE1 (Example 2). We also tested a new pump powered by a new asynchronous motor with IE3 energy efficiency (Example 1). Followed by a description of the used equipment and a presentation of the computer application through which we operated the pump test room. Capturing of the measurements was divided into three different sets relating to obtain hydraulic and electrical data. We obtained both types of data from the pump test application. In addition to the data obtained from the frequency converter, two power analyzers were used to measure electrical data, which measure the electrical quantities on the input and on the output of the frequency converter.
On the basis of the obtained data, we presented the results, compared them with each other and carried out a calculation of the economic viability of the modernization of the lineup. The analysis of the results shows where the optimal pump operating point is located. We have proved that the Example 1 setup achieves a higher pressure height, higher flow rate and higher efficiency of the pumping lineup than the setup from the Example 2. At the end of the thesis, we carried out calculations to determine how much electricity savings are made by replacing an outdated propulsion pumping system, or when the investment will pay off. The findings showed how important properly selected and dimensioned equipment is, as the highest savings were achieved in the operating range of the best efficiency point and by reducing the frequency to 40 Hz.
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