Ljiljana Radovanovic

Combustion characteristics of wheat straw in a fixed bed

ABSTRACT Combustion of wheat straw was investigated in a fixed-bed reactor for two air flow rates, 1,151 and 2,125 kg/m2h. Measured temperatures, mass loss, and gas composition were used to evaluate the combustion characteristics in terms of ignition front speed, burning rate, and quality of combustion in general. At lower value of air flow rate difference between the ignition rate and burning rate was significant, which can be easily noticed by the measurement results. At higher value of air flow rate, there was still a small difference between the ignition and burning rate, while the content of oxygen in the flue gas was 10%, which leads to the conclusion that a change in the method of delivering the combustion air is necessary.

Measures for increasing consumption of natural gas

ABSTRACT This paper provides an overview and analysis of the structure of the energy system and consumers of natural gas on the territory of the Serbia with special attention to one category of consumers – households. It gives an overview of data on the energy system of Serbia – the natural gas sector, concepts, and directions of the development with projections until 2030. In addition to the projection of consumption of natural gas, it also gives the legal framework in force in the field of energy sector in Serbia. It presents data on natural gas consumption in Serbia in the period from 2010 to 2015, with projections of future consumption until year 2030.

Increasing the safety of power plants using a new model of reliability

ABSTRACT The main objective of this paper is to present a new reliability model of thermal power plant in case of power block in TE-KO Kostolac B (Serbia), with the existence of interactions of system component cancellation. It is based on the theory of probability, Weibull distribution, Monte Carlo simulation, and newly discovered mathematical models of component dismissal interaction and original software solutions. The goal of implementation of new model is increased system reliability through reducing the number of failures. Thus, increasing operational safety of thermal power, which is in accordance with the provision of energy security by applying measures of Directive 2005/89/EU. According to the directive, it is necessary to ensure reliable, safe, efficient, and quality power supply.

The Analysis of Energetic and Economic Parameters During the Utilization of Corn Grain as a Fuel for Cereal Dryers

Due to the increase in price of fossil fuel, utilization of biofuel as a renewable type of fuel is getting more cost-effective. In this article, the research results of drying rice grain using corn grain and its waste as a biofuel are presented. Comparative tests were conducted using heating oil and biofuel. The testing was conducted on two batch grain dryers of the same type. The dryers were filled with 32 t of wet rice. In one dryer heating oil was used, and in the other ground corn grain was used as biofuel. Based on the results of the research it was established that using ones own corn from the farm, 60–65% of the financial means can be saved from drying the grain.

Coke formation in pyrolysis furnaces in the petrochemical industry

ABSTRACT In the petrochemical industry, an industrial pyrolysis furnace is a complicated piece of equipment that functions as both a reactor and high-pressure steam generator. During service, hard deposits of carbon (coke) build up on the inner wall of the tube, reducing heat transfer and restricting the flow of the hydrocarbon feedstocks. In this paper, an overview of coke formation, the impact of coke formation, and the methods by which coke formation can be prevented, as well as methods that can be successful in decoking of pyrolysis furnaces, is presented.

Modeling and risk analysis of brine mixing mobile unit operation processes

ABSTRACT This work presents an approach to modeling and risk analysis of operating processes of a brine mixing mobile unit. The main objective was to identify the operations for which the mobile unit was designed as well as to identify all the stakeholders, conditions, requirements, and interactions that occur in the process. Based on these data, a model of the entire process was made, using the BPMN 2.0. notation. This model presents in detail all relevant activities and conditions so that on the basis of it, initial algorithms in the process of execution were established, and then the configurations for the controllers and the user application were made. Furthermore, a detailed analysis of the process in terms of risk assessment and identifying potential failures was made. The primary goal of the research was to describe the use of modeling and the process analysis as well as to point out the critical points and possible improvements of describing the solution.

Energy efficiency analysis of corn cob used as a fuel

ABSTRACT In recent years, man has become more aware of the fact that today’s approach to energy saving is unsustainable. It is believed that in the near future, biomass will increasingly become of interest as one of the most promising renewable energy sources. The paper describes one example of the use of biomass (corn cob) in the process of production of thermal energy, i.e. in the process of seedcorn drying. The purpose of the investigations reported in the paper was to define the use of corn cob as a fuel to increase energy efficiency. Additionally, energy efficiency was explained through hourly consumption of corn cob in thermogens, which was further compared with consumption of conventional fuels (natural gas).

A brine mixing mobile unit in oil and gas industry-An example of a cost-effective, efficient, and environmentally justified technical solution

ABSTRACT The present work shows the technical solution for a mobile unit used for brine mixing in oil and gas industry. Brine is widely used as a fluid when servicing oil and gas wells and pipelines. The use of brine in the process of pipeline overhaul allows safe operation of clogged parts of petroleum wells. In this study, we suggest a technical solution for automated production, storage, and shipping of mentioned brine. The process, methodology, equipment, and implemented “touch panel” application are innovative because they allow cost-effective, efficient, and environmentally safe preparation of brine. The primary goal of the research is to illustrate the use of the mobile unit, as well as innovative importance and usefulness of the process of mixing brine. Furthermore, its aim is to highlight the critical points and possible improvements of described technical solution.

Application of a master meter systemto assure crude oil and natural gas quality during transportation

ABSTRACT This paper discusses an example of the master meter system (MMS), used in the oil and gas industry with the purpose of validating the performance of custody transfer meters. The system can also be used to determine if there are any changes such as the deposition of wax or asphaltic material (in the case of crude oil) or liquids (in the case of natural gas). According to current standards, custody transfer measurements must pass periodic verification of measurement performance, the process which is known as meter proving. This paper presents the construction and key parts, as well as the main functionalities of MMS which comply with the most rigorous requirements for custody transfer. This is achieved by using a novel instrumentation with high level of accuracy, appropriate flow computer and HMI (Human Machine Interface) application developed to support supervision and control of the proving process.

Some aspects of the use of solar energy in Serbia

ABSTRACT This article presents the aspects of solar radiation and the use of solar energy in Serbia. It also considers why Serbia does not use thermal conversion of solar radiation in spite of much greater potential comparing to the countries of the Western and Central Europe, which are leading in the use of solar energy. The low standard of living, low electricity prices, the low level of energy efficiency in all areas of energy use, lack of knowledge, and political decisions are the main causes of insufficient use of renewable energy sources in Serbia.