High mercury emission (both forms: Hg0 and Hg2+) from the wet scrubber in a full-scale lignite-fired power plant

The paper describes and discusses the results of research on mercury behaviour, especially its high emission, in both forms: elemental (Hg-0) and oxidised (Hg2+) from the wet flue gas desulphurisation scrubber (WFGD) in a lignite-fired power plant located in central Europe. The presented results involve the collection of lignite power plant samples (liquid, solid, gas) and different laboratory chemical analyses to try to understand the mechanism of mercury re-emission from the wet flue gas desulfurization system. It was noted that 67-80% of the total inlet mercury concentration left the WFGD scrubber. Moreover, the oxidised form of mercury was the main emitted form (about 60-70% of the total mercury concentration). The results show that mercury was found in very high concentration (10 mu g/g) (range: ppm) in the WFGD solid by-products, whereas the liquid phase contained only 1 mu g//l (range: ppb). Considering literature reports and presented data from the investigated power station, we believe that iron (Fe), which occurs in very high concentrations in solid WFGD samples (1.81% wt. Fe) and lignite (up to 20 g/kg Fe) is mainly responsible for disrupting the mercury absorption in the scrubber, the partitioning of the mercury between phases and leads to its reemission. Moreover, we believe also that a relatively high iodine ion concentration (130 mg/l) in the limestone slurry leads to mercury emission in its oxidised form, mainly as Hgl(2), which is highly volatile. Other minor components from limestone dissolution such as Mn, Al and Mg may additionally enhance that "complex" mercury behaviour.Web of Science270art. no. 11749

Numerical modelling of series-parallel cooling systems in power plant

The paper presents a mathematical model allowing one to study series-parallel hydraulic systems like, e.g., the cooling system of a power boiler's auxiliary devices or a closed cooling system including condensers and cooling towers. The analytical approach is based on a set of non-linear algebraic equations solved using numerical techniques. As a result of the iterative process, a set of volumetric flow rates of water through all the branches of the investigated hydraulic system is obtained. The calculations indicate the influence of changes in the pipeline's geometrical parameters on the total cooling water flow rate in the analysed installation. Such an approach makes it possible to analyse different variants of the modernization of the studied systems, as well as allowing for the indication of its critical elements. Basing on these results, an investor can choose the optimal variant of the reconstruction of the installation from the economic point of view. As examples of such a calculation, two hydraulic installations are described. One is a boiler auxiliary cooling installation including two screw ash coolers. The other is a closed cooling system consisting of cooling towers and condensers

CFD model of SNCR with shifting effect of CO

The paper deals with CFD simulation of SNCR technology with implemented CO temperature shift. The influence of CO on the SNCR process is described by empirical adjustment of kinetics parameters of chemical reactions. Results of CFD simulation were compared with results of experimental measurements. Although the proposed kinetics model of SNCR technology is simplified, it is able to describe reduction of NOx and other phenomena of SNCR with good precision. The model can be used to verify of injection levels and injection lances arrangement at design phase.Web of Science2012210

Numerical modelling of sulphate ion concentration in wastewater from a closed cooling system

The paper presents a mathematical model that allows for predicting daily changes of sulphate ion concentration in water circulating in a closed cooling system consisting of condensers and cooling towers. This is an important issue because an excessive and uncontrolled increase in the concentration of SO42− in the circulating water may cause the corrosion of concrete parts of the channels and cooling towers, as well as an increase in the concentration of calcium salts, which can accelerate the process of its deposition on the exchange surfaces inside condensers. The goal of the paper is to propose an original mathematical model, which under certain simplifications poses an analytical solution to this problem. The approach enables calculating the asymptotic value of the sulphate ion concentration in circulating water, as well as the minimal volumetric flow rate of wastewater allowing the SO42− ion concentration to be preserved below legal limits. The simplified analytical solution enables indicating the optimal volumetric flow rate of wastewater fitting the actual number of working power units. This is especially important because the daily amount of water released from the cooling system as wastewater usually reaches a level of several thousand m3 and its proper management could significantly reduce system maintenance costs

Wastewater management in a closed cooling system of professional power plant

The paper presents a mathematical model describing the changes in SO42- concentration in a closed system of cooling water in a professional power plant. The analyzed installation consists of condensers and cooling towers connected by a system of channels. The main mechanism of heat transfer in the cooling tower bases on partial evaporation of water, resulting in the increase of concentration of SO42- ions in the circulating liquid. The only mechanism to decrease concentration of undesirable chemicals in the circulating water is its periodic discharge to a wastewater treatment. According to the latest Polish Government Regulations (Regulation of the Ministry of Environment dated 18 November 2014) and the Directive of the European Parliament and of the Council (2010/75/EU of 24 November 2010 on industrial emissions) from the beginning of 2016 the new limits on the chemical components of a wastewater led to the natural tanks has been accepted, what forced planned and cost-effective wastewater treatment in a professional power plants. Presented mathematical model has an analytical solution which allows not only to predict daily changes of SO42- concentration in circulating water but also to indicate asymptotic concentration of sulphate ions under given working parameters of the system and to calculate minimal volumetric flow rate of wastewater required to keep the SO42- concentration below legal value.W pracy przedstawiono model matematyczny opisujący zmianę stężenia jonów siarczanowych SO42- w zamkniętym obiegu wody chłodzącej bloku energetycznego. Analizowana instalacja obejmuje: skraplacze bloków energetycznych oraz chłodnie kominowe połączone systemem kanałów ssących i kolektorów tłocznych. Głównym mechanizmem wymiany ciepła w chłodni jest częściowe odparowanie przepływającej przez nią wody, co powoduje jednak wzrost stężeń związków chemicznych w cyrkulującej cieczy i wymusza okresowy zrzut części wody do przyzakładowej oczyszczalni ścieków. Zgodnie z najnowszymi rozporządzeniami prawnymi: Rozporządzeniem Ministra Środowiska z dnia 18 listopada 2014 roku oraz dyrektywą Parlamentu Europejskiego i Rady 2010/75/UE z dnia 24 listopada 2010 r. w sprawie emisji przemysłowych, od początku roku 2016 obowiązują nowe limity dotyczące składu chemicznego ścieków technologicznych kierowanych do zbiorników naturalnych, które wymuszają planową i oszczędną gospodarkę wodnościekową elektrowni. Prezentowany model matematyczny posiada analityczne rozwiązanie pozwalające nie tylko przewidzieć dobowe zmiany stężeń siarczanów w cyrkulującej wodzie, ale również określić graniczne stężenie jonów siarczanowych dla bieżących parametrów pracy układu oraz wyznaczyć minimalny strumień odprowadzanych ścieków zapewniający spełnienie norm emisji ścieków przemysłowych.Web of Science19645

Optimization of Useful Daylight Illuminance for Vertical Shading Fins Covered by Photovoltaic Panels for a Case Study of an Office Room in the City of Wroclaw, Poland

A building’s facade is its main interface with the external environment, as it controls almost all energy flows in the building—losses and gains. In this context, the most recent invention of adaptive façades allows for the introduction of an optimized system for both daylight management and electrical energy production. The authors of the presented paper propose a novel adaptive façade system that is equipped with vertical shading fins of 1 × 4 m that are covered with PV panels. The fins are kinetic and rotate around a vertical axis in order to optimize solar irradiation for producing electricity. The presented adaptive façade is analyzed in two stages. Firstly, the number of vertical shading fins is optimized in the context of useful daylight illuminance (UDI) and daylight glare probability (DGP) using Radiance-cored software. Next, two scenarios of PV installation are verified for fixed and the Sun-tracking solution. The results show that the Sun-tracking system is more efficient than the fixed one, but electricity production is only increased by 3.21%. The reason for this is the fact that—while following the Sun’s azimuth position—fins shade each other and reduce the effective area of the adjacent PV panels. Based on this, the authors conclude that the Sun-tracking system might be justified due to its protective or decorative function and not because of its improved effectiveness in generating electrical energy

Numerical modelling of series-parallel cooling systems in power plant

The paper presents a mathematical model allowing one to study series-parallel hydraulic systems like, e.g., the cooling system of a power boiler's auxiliary devices or a closed cooling system including condensers and cooling towers. The analytical approach is based on a set of non-linear algebraic equations solved using numerical techniques. As a result of the iterative process, a set of volumetric flow rates of water through all the branches of the investigated hydraulic system is obtained. The calculations indicate the influence of changes in the pipeline's geometrical parameters on the total cooling water flow rate in the analysed installation. Such an approach makes it possible to analyse different variants of the modernization of the studied systems, as well as allowing for the indication of its critical elements. Basing on these results, an investor can choose the optimal variant of the reconstruction of the installation from the economic point of view. As examples of such a calculation, two hydraulic installations are described. One is a boiler auxiliary cooling installation including two screw ash coolers. The other is a closed cooling system consisting of cooling towers and condensers

Optimization of Useful Daylight Illuminance for Vertical Shading Fins Covered by Photovoltaic Panels for a Case Study of an Office Room in the City of Wroclaw, Poland

A building’s facade is its main interface with the external environment, as it controls almost all energy flows in the building—losses and gains. In this context, the most recent invention of adaptive façades allows for the introduction of an optimized system for both daylight management and electrical energy production. The authors of the presented paper propose a novel adaptive façade system that is equipped with vertical shading fins of 1 × 4 m that are covered with PV panels. The fins are kinetic and rotate around a vertical axis in order to optimize solar irradiation for producing electricity. The presented adaptive façade is analyzed in two stages. Firstly, the number of vertical shading fins is optimized in the context of useful daylight illuminance (UDI) and daylight glare probability (DGP) using Radiance-cored software. Next, two scenarios of PV installation are verified for fixed and the Sun-tracking solution. The results show that the Sun-tracking system is more efficient than the fixed one, but electricity production is only increased by 3.21%. The reason for this is the fact that—while following the Sun’s azimuth position—fins shade each other and reduce the effective area of the adjacent PV panels. Based on this, the authors conclude that the Sun-tracking system might be justified due to its protective or decorative function and not because of its improved effectiveness in generating electrical energy

Investigation of the Durability of Gaskets in Contact with Bio- and Aviation Fuels

Care for the natural environment, which can be observed in the tightening of emission standards, has enforced the search for new fuels, especially renewable sources of natural origin. The article presents the results of theoretical and experimental considerations on the impact of aviation biofuels on the materials used for sealing flange joints. The fuel type selected for the test is compatible with aviation fuels. Fuels have been enriched with a bio-additive that changes the technical and physical properties of the fuel. The tested gaskets were made of soft, aramid-elastomeric materials that were flat in shape and without reinforcement. Their commercial names are AFO and AFM. Tests were carried out with the use of a simple flange joint with a fuel reservoir at 373 K. Both fuel loss and the pressure drop on the gasket were measured during a 1000 h period of time. The experiments showed that the seals preserved the technical parameters in the presence of the tested fuels. The fuel loss did not exceed the accepted limits, which demonstrates the suitability of the tested materials for utilization with new types of fuel. However, no unequivocal conclusions can be drawn about the positive or negative impact of bio-additives on the sealing material due to the fact that both an improvement and deterioration in tightness under certain circumstances were observed. Based on the experimental data, a mathematical model was proposed that makes it possible to predict the service life of the gaskets in flange joints in contact with the investigated types of fuel. The potential application of the research results is practical information about the impact of biofuel on the gasket, and hence the information about the possibility of using traditional sealing materials in a new application—for sealing installations for the production, transmission and storage of biofuels

Study of heat exchange processes in a screw ash cooler installation

The paper presents an example of the thermal-flow analysis of a bottom ash cooler cooperating with a circulating fluidized bed (CFB) boiler. The authors present the methodology of the conducted studies and examples of thermal balance calculations basing on measurement results. The comparison of two different ash coolers indicates a significant relationship between the outlet temperatures of the ash and cooling water depending on the construction and arrangement of the analysed ash coolers. The analysis presented in this paper enables determining the optimal rotation speed of the screw in order to achieve the required temperature of the slag depending on the actual working parameters of the CFB boiler. It provides an opportunity to optimize the heat exchange conditions in order to obtain the highest acceptable water temperature at the outlet of the ash cooler while adhering to safety regulations. The hot water could further be used for internal sanitary purposes or to support heating systems operating in the power plant