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Miroslav Variny
Institute of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, 812 37 Bratislava, Slovakia

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Short Biography

Miroslav Variny received his MSc and PhD in Chemical Engineering at the Slovak University of Technology (STU) in Bratislava, Slovakia, in 2007 and 2011 respectively and was awarded the Aurel Stodola prize from ENEL Slovakia for the best defended PhD. thesis in the field of energy technologies that year. Currently a researcher at the Institute of Chemical and Environmental Engineering of STU, he applies his experiences from previously-conducted energy-saving projects and energy audits for industrial companies, especially in the refining, petrochemical, and pulp and paper production sector. His research focuses on cogeneration and polygeneration, energy audits, renewable energy sources, energy-saving technologies, energy efficiency, and environmental impact of industrial plants. He serves as reviewer for MDPI journals (Processes, Energies, Applied Sciences) and Elsevier journals (Energy, Applied Thermal Engineering, Journal of Cleaner Production). He has been a member of the board of the Slovak Society of Chemical Engineering since 2016.

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Journal article
Published: 06 August 2021 in Processes
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Multi-objective (energy–economic–safety) assessment of ethyl acetate production involving a heat pump is presented in this paper. The heat pump is designed to intensify ethyl acetate separation and to reduce the total operating cost. Two ethyl acetate production pathways are upgraded using a heat pump, conventional process and reactive distillation column with a separation unit. Detailed process models including the heat pump environment have been compiled and optimized in the Aspen Plus software. Both benefits and drawbacks of including the heat pump in the processes are evaluated using three different points of view: process energy, economics, and safety. As a result, using a heat pump is highly recommended in both conventional process and reactive distillation column with a separation unit. As a higher level of process integration is achieved using a heat pump, economic aspects are improved; however, safety aspects deteriorate. The final decision on the suitability of using a heat pump depends on whether it is proposed for an existing plant, or a completely new plant is designed. In a new plant, the concept of a thermally coupled process (reactive distillation column with a stripper column) has been proven to be the most promising.

ACS Style

Branislav Šulgan; Juraj Labovský; Miroslav Variny; Zuzana Labovská. Multi-Objective Assessment of Heat Pump-Assisted Ethyl Acetate Production. Processes 2021, 9, 1380 .

AMA Style

Branislav Šulgan, Juraj Labovský, Miroslav Variny, Zuzana Labovská. Multi-Objective Assessment of Heat Pump-Assisted Ethyl Acetate Production. Processes. 2021; 9 (8):1380.

Chicago/Turabian Style

Branislav Šulgan; Juraj Labovský; Miroslav Variny; Zuzana Labovská. 2021. "Multi-Objective Assessment of Heat Pump-Assisted Ethyl Acetate Production." Processes 9, no. 8: 1380.

Comment
Published: 09 April 2021 in International Journal of Environmental Research and Public Health
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This paper responds to the article by Pietrapertosa et al., doi:10.3390/ijerph17124434, published previously in the International Journal of Environmental Research and Public Health. Its aim is to discuss the appropriateness of the studied method, to analyze its weak sides and to propose its robustness improvement. Thus, data presented in the above study were examined and recalculated, yielding, among others, indicators of annual energy savings (in kWh per m2 of total heated area) and specific proposals investment costs (in € per m2 of total heated area). By analyzing the obtained data for all public buildings, a significantly simplified approach to this problematic has been suggested while several other features of the research method and some presented results lack proper reasoning and discussion. Individual approach to each public building has been proposed and discussed point-by-point to enhance the method’s applicability. As a result, more realistic outcomes are obtained, and suitable investment actions can be proposed.

ACS Style

Miroslav Variny. Comment on Pietrapertosa et al. How to Prioritize Energy Efficiency Intervention in Municipal Public Buildings to Decrease CO2 Emissions? A Case Study from Italy. Int. J. Environ. Res. Public Health 2020, 17, 4434. International Journal of Environmental Research and Public Health 2021, 18, 3961 .

AMA Style

Miroslav Variny. Comment on Pietrapertosa et al. How to Prioritize Energy Efficiency Intervention in Municipal Public Buildings to Decrease CO2 Emissions? A Case Study from Italy. Int. J. Environ. Res. Public Health 2020, 17, 4434. International Journal of Environmental Research and Public Health. 2021; 18 (8):3961.

Chicago/Turabian Style

Miroslav Variny. 2021. "Comment on Pietrapertosa et al. How to Prioritize Energy Efficiency Intervention in Municipal Public Buildings to Decrease CO2 Emissions? A Case Study from Italy. Int. J. Environ. Res. Public Health 2020, 17, 4434." International Journal of Environmental Research and Public Health 18, no. 8: 3961.

Journal article
Published: 01 February 2021 in Metals
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Oxygen-enhanced combustion (OEC) is a useful method for improving the efficiency of thermal plants and for decreasing greenhouse gas (GHG) emissions. Basic and modified burner designs utilizing OEC in the aluminum melting process in a rotary tilting furnace were studied. A combined approach comprising experimental measurement and simulation modeling was adopted aimed at assessing GHG emissions production. Reduction of up to 60% fuel consumption of the total natural gas used in the laboratory-scale furnace was achieved. The optimal oxygen concentration in the oxidizer regarding the amount of total GHG emissions produced per charge expressed as CO2 equivalent was 35% vol. Its further increase led only to marginal fuel savings, while the nitrogen oxide emissions increased rapidly. Using the modified burner along with OEC led to around 10% lower CO2 emissions and around 15% lower total GHG emissions, compared to using a standard air/fuel burner. CFD simulations revealed the reasons for these observations: improved mixing patterns and more uniform temperature field. Modified burner application, moreover, enables furnace productivity to be increased by shortening the charge melting time by up to 16%. The presented findings demonstrate the feasibility of the proposed burner modification and highlight its better energy and environmental performance indicators, while indicating the optimal oxygen enrichment level in terms of GHG emissions for the OEC technology applied to aluminum melting.

ACS Style

Róbert Dzurňák; Augustín Varga; Gustáv Jablonský; Miroslav Variny; Marcel Pástor; Ladislav Lukáč. Analyzing the Formation of Gaseous Emissions during Aluminum Melting Process with Utilization of Oxygen-Enhanced Combustion. Metals 2021, 11, 242 .

AMA Style

Róbert Dzurňák, Augustín Varga, Gustáv Jablonský, Miroslav Variny, Marcel Pástor, Ladislav Lukáč. Analyzing the Formation of Gaseous Emissions during Aluminum Melting Process with Utilization of Oxygen-Enhanced Combustion. Metals. 2021; 11 (2):242.

Chicago/Turabian Style

Róbert Dzurňák; Augustín Varga; Gustáv Jablonský; Miroslav Variny; Marcel Pástor; Ladislav Lukáč. 2021. "Analyzing the Formation of Gaseous Emissions during Aluminum Melting Process with Utilization of Oxygen-Enhanced Combustion." Metals 11, no. 2: 242.

Review
Published: 05 January 2021 in Processes
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Co-combustion of biomass-based fuels and fossil fuels in power plant boilers, utility boilers, and process furnaces is a widely acknowledged means of efficient heat and power production, offering higher power production than comparable systems with sole biomass combustion. This, in combination with CO2 and other greenhouse gases abatement and low specific cost of system retrofit to co-combustion, counts among the tangible advantages of co-combustion application. Technical and operational issues regarding the accelerated fouling, slagging, and corrosion risk, as well as optimal combustion air distribution impact on produced greenhouse gases emissions and ash properties, belong to intensely researched topics nowadays in parallel with the combustion aggregates design optimization, the advanced feed pretreatment techniques, and the co-combustion life cycle assessment. This review addresses the said topics in a systematic manner, starting with feed availability, its pretreatment, fuel properties and combustor types, followed by operational issues, greenhouse gases, and other harmful emissions trends, as well as ash properties and utilization. The body of relevant literature sources is table-wise classified according to numerous criteria pertaining to individual paper sections, providing a concise and complex insight into the research methods, analyzed systems, and obtained results. Recent advances achieved in individual studies and the discovered synergies between co-combusted fuels types and their shares in blended fuel are summed up and discussed. Actual research challenges and prospects are briefly touched on as well.

ACS Style

Miroslav Variny; Augustín Varga; Miroslav Rimár; Ján Janošovský; Ján Kizek; Ladislav Lukáč; Gustáv Jablonský; Otto Mierka. Advances in Biomass Co-Combustion with Fossil Fuels in the European Context: A Review. Processes 2021, 9, 100 .

AMA Style

Miroslav Variny, Augustín Varga, Miroslav Rimár, Ján Janošovský, Ján Kizek, Ladislav Lukáč, Gustáv Jablonský, Otto Mierka. Advances in Biomass Co-Combustion with Fossil Fuels in the European Context: A Review. Processes. 2021; 9 (1):100.

Chicago/Turabian Style

Miroslav Variny; Augustín Varga; Miroslav Rimár; Ján Janošovský; Ján Kizek; Ladislav Lukáč; Gustáv Jablonský; Otto Mierka. 2021. "Advances in Biomass Co-Combustion with Fossil Fuels in the European Context: A Review." Processes 9, no. 1: 100.

Journal article
Published: 19 November 2020 in Processes
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Optimal steam process drive sizing is crucial for efficient and sustainable operation of energy-intense industries. Recent years have brought several methods assessing this problem, which differ in complexity and user-friendliness. In this paper, a novel complex method was developed and presented and its superiority over other approaches was documented on an industrial case study. Both the process-side and steam-side characteristics were analyzed to obtain correct model input data: Driven equipment performance and efficiency maps were considered, off-design and seasonal operation was studied, and steam network topology was included. Operational data processing and sizing calculations were performed in a linked MATLAB®–Aspen Plus® environment, exploiting the strong sides of both software tools. The case study aimed to replace a condensing steam turbine by a backpressure one, revealing that: 1. Simpler methods neglecting frictional pressure losses and off-design turbine operation efficiency loss undersized the drive and led to unacceptable loss of deliverable power to the process; 2. the associated process production loss amounted up to 20%; 3. existing bottlenecks in refinery steam pipelines operation were removed; however, new ones were created; and 4. the effect on the marginal steam source operation may vary seasonally. These findings accentuate the value and viability of the presented method.

ACS Style

Patrik Furda; Miroslav Variny; Zuzana Labovská; Tomáš Cibulka. Process Drive Sizing Methodology and Multi-Level Modeling Linking MATLAB® and Aspen Plus® Environment. Processes 2020, 8, 1495 .

AMA Style

Patrik Furda, Miroslav Variny, Zuzana Labovská, Tomáš Cibulka. Process Drive Sizing Methodology and Multi-Level Modeling Linking MATLAB® and Aspen Plus® Environment. Processes. 2020; 8 (11):1495.

Chicago/Turabian Style

Patrik Furda; Miroslav Variny; Zuzana Labovská; Tomáš Cibulka. 2020. "Process Drive Sizing Methodology and Multi-Level Modeling Linking MATLAB® and Aspen Plus® Environment." Processes 8, no. 11: 1495.

Journal article
Published: 03 November 2020 in Forests
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Research Highlights: As to fill the current knowledge gap and to deliver important findings to the scientific community, efficient sulfur recovery from black liquor gasifier syngas, comprising both gas cleaning and returning sulfur to the pulping process, was modeled and assessed from a techno-economic viewpoint. This manuscript proves that the associated investment and operational costs cannot be neglected and that they impact the black liquor gasification feasibility significantly. To prove its gasification as a sustainable and more efficient processing route over its combustion in recovery boilers, a substantial process efficiency improvement and operating costs reduction must be targeted in future research. Background and Objectives: Sulfur compounds found in black liquor partly turn into hydrogen sulfide during gasification and exit the gasifier in the syngas. Their efficient recovery in their sulfidic form to the pulping process is of utmost importance. Current studies focus on black liquor gasifier syngas desulfurization only. Materials and Methods: A mathematical model of two H2S absorption units from a 66.7 tDS/h (1600 tons dry solids per day) black liquor gasification process to 20 ppm H2S content in cleaned syngas using either white liquor plus NaOH or N-methyldiethanolamine (MDEA) was created using the Aspen Plus simulation software. Results: The results show that CO2 co-absorption significantly increases the lime kiln load: +20% in the MDEA alternative and +100% in the other one. The MDEA alternative requires almost the same investment costs but by around USD 9.7 million (>50%) lower annual operating costs compared to the other one. Economic evaluation was based on the assumed discount rate of 5% and on the expected plant operation time of 25 years. The estimated total investment cost of the whole plant is around USD 170 million for both alternatives. The whole plant including this alternative exhibits a positive net present value (over USD 19 million), an internal rate of return of 5% and a profitability index of 1.12, whereas that with the other alternative is economically infeasible. Conclusions: The MDEA-based syngas cleaning technology represents a more efficient and economically feasible option of sulfur recovery. A major drawback of both modeled syngas cleaning technologies is that their estimated annual operating costs significantly reduce the expected profit margin of gasification over the traditional black liquor combustion in a recovery boiler. Syngas cleaning and sulfur recovery have to be further optimized to reach a significant cut down in operational costs to improve the economic feasibility of black liquor gasification.

ACS Style

Michal Hruška; Miroslav Variny; Juma Haydary; Ján Janošovský. Sulfur Recovery from Syngas in Pulp Mills with Integrated Black Liquor Gasification. Forests 2020, 11, 1173 .

AMA Style

Michal Hruška, Miroslav Variny, Juma Haydary, Ján Janošovský. Sulfur Recovery from Syngas in Pulp Mills with Integrated Black Liquor Gasification. Forests. 2020; 11 (11):1173.

Chicago/Turabian Style

Michal Hruška; Miroslav Variny; Juma Haydary; Ján Janošovský. 2020. "Sulfur Recovery from Syngas in Pulp Mills with Integrated Black Liquor Gasification." Forests 11, no. 11: 1173.

Journal article
Published: 15 October 2020 in Processes
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Air infiltration into the combustion chambers of industrial furnaces is an unwanted phenomenon causing loss of thermal efficiency, fuel consumption increase, and the subsequent increase in operating costs. In this study, a novel design for a rotary tilting furnace door with improved construction features is proposed and tested experimentally in a laboratory-scale furnace, aimed at air infiltration rate reduction by decreasing the gap width between the static furnace door and the rotating body. Temperatures in the combustion chamber and oxygen content in the dry flue gas were measured to document changes in the combustion process with the varying gap width. Volumetric flow values of infiltrating air calculated based on measured data agree well with results of numerical simulations performed in ANSYS and with the reference calculation procedure used in relevant literature. An achievable air infiltration reduction of up to 50% translates into fuel savings of around 1.79 to 12% of total natural gas consumption of the laboratory-scale furnace. The average natural gas consumption increase of around 1.6% due to air infiltration into industrial-scale furnaces can thus likewise be halved, representing fuel savings of almost 0.3 m3 per ton of charge.

ACS Style

Róbert Dzurňák; Augustin Varga; Gustáv Jablonský; Miroslav Variny; Réne Atyafi; Ladislav Lukáč; Marcel Pástor; Ján Kizek. Influence of Air Infiltration on Combustion Process Changes in a Rotary Tilting Furnace. Processes 2020, 8, 1292 .

AMA Style

Róbert Dzurňák, Augustin Varga, Gustáv Jablonský, Miroslav Variny, Réne Atyafi, Ladislav Lukáč, Marcel Pástor, Ján Kizek. Influence of Air Infiltration on Combustion Process Changes in a Rotary Tilting Furnace. Processes. 2020; 8 (10):1292.

Chicago/Turabian Style

Róbert Dzurňák; Augustin Varga; Gustáv Jablonský; Miroslav Variny; Réne Atyafi; Ladislav Lukáč; Marcel Pástor; Ján Kizek. 2020. "Influence of Air Infiltration on Combustion Process Changes in a Rotary Tilting Furnace." Processes 8, no. 10: 1292.

Journal article
Published: 07 October 2020 in Processes
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A project of a new milk drying unit processing 4800 kg/h of fresh milk into milk powder with expected steam consumption of 1000 kg/h (equivalent to ca. 2.6 GJ/h) was assessed. In this paper, investment profitability of this project was analyzed combining mathematical modeling, market analysis, and parametric sensitivity study. Aspen Plus was used as the simulation environment to determine values of key process variables—major streams, mass flows, and energy consumption. Co-digestion of cattle manure in an adjacent biogas plant was considered to provide biogas to partially or completely substitute natural gas as an energy source. As biogas composition from potential co-digestion was unknown, variable methane content from 45 to 60 mol.% was considered. In the next step, thorough economic analysis was conducted. Diverse effects of biogas addition depending on market prices, biogas treatment costs, and biogas methane content were simulated and evaluated. In a market situation closest to reality, biogas mixing to boiler fuel decreased simple payback period from 11.2 years to 5.1 years. However, if biogas treatment costs were high (final biogas price equal to or above 0.175 EUR/m3), the simple payback period was increased two- to sixfold, making the analyzed project practically unfeasible.

ACS Style

Ján Janošovský; Eva Marková; Adriána Kačmárová; Miroslav Variny. Green Dairy Plant: Process Simulation and Economic Analysis of Biogas Use in Milk Drying. Processes 2020, 8, 1262 .

AMA Style

Ján Janošovský, Eva Marková, Adriána Kačmárová, Miroslav Variny. Green Dairy Plant: Process Simulation and Economic Analysis of Biogas Use in Milk Drying. Processes. 2020; 8 (10):1262.

Chicago/Turabian Style

Ján Janošovský; Eva Marková; Adriána Kačmárová; Miroslav Variny. 2020. "Green Dairy Plant: Process Simulation and Economic Analysis of Biogas Use in Milk Drying." Processes 8, no. 10: 1262.

Journal article
Published: 05 August 2020 in Processes
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Nitrogen oxides (NOx) from combustion contribute significantly to atmospheric pollution. An experimental setup was employed to investigate the application of three primary denitrification methods, i.e., reburning (staged combustion), overfiring air (OFA), and flue-gas recirculation (FGR), individually and in combination, combusting natural gas (NG) and propane–butane gas (PBG). Fuel heat inputs of 16 and 18 kW and air excess coefficients of 1.1 and 1.2, respectively, were tested. The highest individual denitrification efficiency of up to 74% was obtained for FGR, followed by reburning and OFA. A denitrification efficiency between 8.9% (reburning + OFA) and 72% (reburning + OFA + FGR) with NG combustion was observed. Using a 20% FGR rate yielded denitrification efficiency of 74% for NG and 65% for PBG and also led to a significant decrease in carbon monoxide (CO) emissions, so this can be recommended as the most efficient denitrification and de-CO method in small-scale furnaces. Reburning alone led to a sharp, more than 12-fold increase in CO emissions compared to the amount without any other method application. The presented results and the difference between our experimental data and the literature data acquired in some other studies indicate the need for further research.

ACS Style

Ladislav Lukáč; Miroslav Rimár; Miroslav Variny; Ján Kizek; Peter Lukáč; Gustáv Jablonský; Ján Janošovský; Marcel Fedák. Experimental Investigation of Primary De-NOx Methods Application Effects on NOx and CO Emissions from a Small-Scale Furnace. Processes 2020, 8, 940 .

AMA Style

Ladislav Lukáč, Miroslav Rimár, Miroslav Variny, Ján Kizek, Peter Lukáč, Gustáv Jablonský, Ján Janošovský, Marcel Fedák. Experimental Investigation of Primary De-NOx Methods Application Effects on NOx and CO Emissions from a Small-Scale Furnace. Processes. 2020; 8 (8):940.

Chicago/Turabian Style

Ladislav Lukáč; Miroslav Rimár; Miroslav Variny; Ján Kizek; Peter Lukáč; Gustáv Jablonský; Ján Janošovský; Marcel Fedák. 2020. "Experimental Investigation of Primary De-NOx Methods Application Effects on NOx and CO Emissions from a Small-Scale Furnace." Processes 8, no. 8: 940.

Journal article
Published: 13 July 2020 in Sustainability
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The performance of an adsorptive heat-moisture regenerator based on a silica gel–sodium sulphate composite adsorbent was studied. The correlation between the adsorbent composition and structural characteristics of the laboratory-scale device was investigated. An algorithm for the calculation of the efficiency factors of the adsorptive regenerator was further developed. The suggested algorithm calculates the operational parameters, including the temperatures, humidities and volumetric flows of internal and external air, and estimates the regenerator’s performance via temperature and moisture efficiency factors, total adsorption and time needed to achieve maximum adsorption, air pressure loss and fan power input. The validity of the calculation results obtained using the proposed algorithm was confirmed experimentally. Temperature efficiency factor, air pressure loss and fan power consumption are crucial parameters for the estimation of the optimal operating regime of an adsorptive heat-moisture regenerator. The correlation between meteorological conditions and efficiency factors was assessed and applied in a simulation of residential house-scale air conditioning unit operation. Maximal values of temperature efficiency factor were found at internal and external air temperatures of 15 to 20 °C and −5 to 0 °C, respectively. Moisture efficiency factors were observed to reach their maximum at the absolute humidities of external and internal air of 4.0 to 5.0 g/m3 and 2.75 to 3.0 g/m3, respectively. The fan power consumption of the adsorptive heat-moisture regenerator was found to be comparable to or even lower than that of commercial air conditioning units used in comparably voluminous interiors.

ACS Style

Elena Belyanovskaya; Miroslav Rimár; Roman Lytovchenko; Miroslav Variny; Kostyantyn Sukhyy; Oleksandr Yeromin; Mikhailo Sykhyy; Elena Prokopenko; Irina Sukha; Mikhailo Gubinskyi; Ján Kizek. Performance of an Adsorptive Heat-Moisture Regenerator Based on Silica Gel–Sodium Sulphate. Sustainability 2020, 12, 5611 .

AMA Style

Elena Belyanovskaya, Miroslav Rimár, Roman Lytovchenko, Miroslav Variny, Kostyantyn Sukhyy, Oleksandr Yeromin, Mikhailo Sykhyy, Elena Prokopenko, Irina Sukha, Mikhailo Gubinskyi, Ján Kizek. Performance of an Adsorptive Heat-Moisture Regenerator Based on Silica Gel–Sodium Sulphate. Sustainability. 2020; 12 (14):5611.

Chicago/Turabian Style

Elena Belyanovskaya; Miroslav Rimár; Roman Lytovchenko; Miroslav Variny; Kostyantyn Sukhyy; Oleksandr Yeromin; Mikhailo Sykhyy; Elena Prokopenko; Irina Sukha; Mikhailo Gubinskyi; Ján Kizek. 2020. "Performance of an Adsorptive Heat-Moisture Regenerator Based on Silica Gel–Sodium Sulphate." Sustainability 12, no. 14: 5611.

Journal article
Published: 22 May 2020 in Processes
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Steam network operation stability and reliability is vital for any industrial branch. A combined steam network model comprising a balance and a coupled thermo-hydrodynamic model, including seasonal variations impact and system specificities, is presented. A balance model can readily be used by a refinery’s operators. The thermo-hydrodynamic model identifies system bottlenecks and cold spots and evaluates proposed operation and investment measures including heat loss reduction. A three-pressure levels refinery steam network served for model testing and validation. Balance model results reveal significant misbalance in steam production and consumption, reaching 30.5% in the low-pressure steam system, and heat balance differences in the range of 9.2% to 29.5% on individual pressure levels, attributable both to flow measurement accuracy issues and to heat losses. The thermo-hydrodynamic model results differ from the measured steam parameters by less than 5% (temperature) and by less than 4% (pressure), respectively, with the estimated operational insulation heat conductivity exceeding 0.08 W/m/K. Its comparison with that of 0.03 W/m/K for dry insulation material yields the need for pipelines re-insulation and a partial revamp of the steam network. The model is sufficiently general for any type of industry, pursuing the goal of cleaner and energy-efficient steam transport and consumption.

ACS Style

Kristián Hanus; Miroslav Variny; Peter Illés. Assessment and Prediction of Complex Industrial Steam Network Operation by Combined Thermo-Hydrodynamic Modeling. Processes 2020, 8, 622 .

AMA Style

Kristián Hanus, Miroslav Variny, Peter Illés. Assessment and Prediction of Complex Industrial Steam Network Operation by Combined Thermo-Hydrodynamic Modeling. Processes. 2020; 8 (5):622.

Chicago/Turabian Style

Kristián Hanus; Miroslav Variny; Peter Illés. 2020. "Assessment and Prediction of Complex Industrial Steam Network Operation by Combined Thermo-Hydrodynamic Modeling." Processes 8, no. 5: 622.

Journal article
Published: 05 February 2020 in Processes
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Alkylate produced by catalyzed reaction of isobutane and olefin-rich streams is a desired component for gasoline blending. Fractionation of the alkylation reactor effluent is energy demanding due to the presence of close boiling point components and solutions cutting its energy intensity; expenses associated with this process are investigated intensely nowadays. This paper presents a novel conceptual design and techno-economic analysis of alkylation reaction effluent fractionation revamp to reach a cut in energy costs of the fractionation process without the need to revamp the rectification columns themselves, providing thus an alternative approach to a more sustainable alkylation process. Two cases are considered—A. additional steam turbine installation or B. combustion engine-driven heat pump-assisted rectification. Mathematical modeling of the considered system and its revamp is applied using the “frozen technology” approach. Real system operation features and seasonal variations are included considering the refinery’s combined heat and power (CHP) unit operation and CO2 emissions balance both internal and external to the refinery. Case A yields an expectable yearly benefit (saved energy minus additionally consumed energy minus CO2 emissions increase; expressed in financial terms) of €110–140 thousand, net present value (NPV) of −€18 to €272 thousand and produces 3.3 GWh/year of electric energy. Case B delivers a benefit of €900–1200 thousand, NPV of −€293 to €2823 thousand while producing 33 GWh/year of electricity. Both cases exhibit analogous simple payback periods (8–10 years). Marginal electric efficiency of Case B (78.3%) documents the energy integration level in this case, exploiting the system and CHP unit operation synergies. CHP unit summer operation mode and steam network restrictions significantly affect the seasonal benefit of Case B. CO2 emissions increase in both cases, Case A and Case B, considering the refinery level. However, including external CO2 emissions leads to emissions decrease in both cases of up to 26 kton/year (Case B.) The presented results document the viability of the proposed concepts comparable to the traditional (reference) solution of a high performance (COP = 8) heat pump while their performance sensitivity stresses the need for complex techno-economic assessment.

ACS Style

Miroslav Variny; Patrik Furda; Ladislav Švistun; Miroslav Rimár; Ján Kizek; Norbert Kováč; Peter Illés; Ján Janošovský; Jakub Váhovský; Otto Mierka. Novel Concept of Cogeneration-Integrated Heat Pump-Assisted Fractionation of Alkylation Reactor Effluent for Increased Power Production and Overall CO2 Emissions Decrease. Processes 2020, 8, 183 .

AMA Style

Miroslav Variny, Patrik Furda, Ladislav Švistun, Miroslav Rimár, Ján Kizek, Norbert Kováč, Peter Illés, Ján Janošovský, Jakub Váhovský, Otto Mierka. Novel Concept of Cogeneration-Integrated Heat Pump-Assisted Fractionation of Alkylation Reactor Effluent for Increased Power Production and Overall CO2 Emissions Decrease. Processes. 2020; 8 (2):183.

Chicago/Turabian Style

Miroslav Variny; Patrik Furda; Ladislav Švistun; Miroslav Rimár; Ján Kizek; Norbert Kováč; Peter Illés; Ján Janošovský; Jakub Váhovský; Otto Mierka. 2020. "Novel Concept of Cogeneration-Integrated Heat Pump-Assisted Fractionation of Alkylation Reactor Effluent for Increased Power Production and Overall CO2 Emissions Decrease." Processes 8, no. 2: 183.

Correspondence
Published: 08 January 2020 in Journal of Cleaner Production
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We respond to the article “Multi-objective optimization for design of a steam system with drivers option in process industries”, published in the Journal of Cleaner Production by Wu et al. (2016), (https://doi.org/10.1016/j.jclepro.2016.04.067). Our aim is to show that a number of incorrect assumptions employed in the analysis methodology together with many inconsistencies, discrepancies and calculation errors led to invalid results and conclusions. The most important scientific flaws included: 1. Omission of varying system complexity impact on optimization approach; 2. Application of several incorrect equations; 3. Mismatch in steam mass and heat balances; 4. Assumption of fixed high and middle pressure steam parameters, independent on system operation; 5. Omission of exported steam value in the optimization procedure. Article of Wu et al. (2016) could provide misleading input when future investment or revamp decisions are made.

ACS Style

Miroslav Variny; Ján Janošovský. Reevaluation of optimal turbine/motor process drivers selection concept proposed by Wu et al. (2016). Journal of Cleaner Production 2020, 253, 120029 .

AMA Style

Miroslav Variny, Ján Janošovský. Reevaluation of optimal turbine/motor process drivers selection concept proposed by Wu et al. (2016). Journal of Cleaner Production. 2020; 253 ():120029.

Chicago/Turabian Style

Miroslav Variny; Ján Janošovský. 2020. "Reevaluation of optimal turbine/motor process drivers selection concept proposed by Wu et al. (2016)." Journal of Cleaner Production 253, no. : 120029.

Journal article
Published: 01 November 2019 in Environmental Engineering Science
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This study is focused on reactive absorption of nitrogen oxides created during calcium nitrate fertilizer production. A functional mathematical process model was set up to verify the process by experimental data and to devise modifications of a real plant with this technology. Suggestions for nitrogen oxide removal efficiency improvement, including changes in operational parameters and plant layout were simulated in Aspen Plus, to achieve compliance with the European legislative emission limit of 300 ppm (mg/m3) of NOx in the off-gas released to the atmosphere. Neither of the suggested process modifications, be it an increase in column packing specific area, increase in packing height, liquid recycles cooling to ambient temperature or make-up absorbent flow rate increase led to sufficient NOx concentration decrease. Addition of a H2O2 solution into the second column was proposed to scavenge the remaining NO as it contributes mostly to the overall NOx emissions. Simulation results indicate this as a viable option to both meet the legislative criteria and to avoid liquid streams' contamination so they can be reprocessed instead of being dealt with as waste.

ACS Style

Elena Kurillová; Katarína Gazdová; Miroslav Variny; Peter Fecko. Efficiency Improvement in Reactive Absorption of Nitrogen Oxides. Environmental Engineering Science 2019, 36, 1433 -1442.

AMA Style

Elena Kurillová, Katarína Gazdová, Miroslav Variny, Peter Fecko. Efficiency Improvement in Reactive Absorption of Nitrogen Oxides. Environmental Engineering Science. 2019; 36 (11):1433-1442.

Chicago/Turabian Style

Elena Kurillová; Katarína Gazdová; Miroslav Variny; Peter Fecko. 2019. "Efficiency Improvement in Reactive Absorption of Nitrogen Oxides." Environmental Engineering Science 36, no. 11: 1433-1442.

Journal article
Published: 25 October 2019 in Processes
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This study of process heat source change in industrial conditions has been developed to aid engineers and energy managers with working towards sustainable production. It allows for an objective assessment from energetic, environmental, and economic points of view, thereby filling the gap in the systematic approach to this problem. This novel site-wide approach substantially broadens the traditional approach, which is based mostly on “cheaper” and “cleaner” process heat sources’ application and only takes into account local changes, while neglecting the synergic effect on the whole facility’s operations. The mathematical model employed assesses the performance change of all the affected refinery parts. The four proposed aromatic splitting process layouts, serving as a case study, indicate feasible heat and condensate conservation possibilities. Although the estimated investment needed for the most viable layout is over €4.5 million, its implementation could generate benefits of €0.5–1.5 million/year, depending on the fuel and energy prices as well as on the carbon dioxide emissions cost. Its economics is most sensitive to the steam to refinery fuel gas cost ratio, as a 10% change alters the resulting benefit by more than €0.5 million. The pollutant emissions generated in the external power production process contribute significantly to the total emissions balance.

ACS Style

Miroslav Variny; Dominika Jediná; Ján Kizek; Peter Illés; Ladislav Lukáč; Ján Janošovský; Marián Lesný. An Investigation of the Techno-Economic and Environmental Aspects of Process Heat Source Change in a Refinery. Processes 2019, 7, 776 .

AMA Style

Miroslav Variny, Dominika Jediná, Ján Kizek, Peter Illés, Ladislav Lukáč, Ján Janošovský, Marián Lesný. An Investigation of the Techno-Economic and Environmental Aspects of Process Heat Source Change in a Refinery. Processes. 2019; 7 (11):776.

Chicago/Turabian Style

Miroslav Variny; Dominika Jediná; Ján Kizek; Peter Illés; Ladislav Lukáč; Ján Janošovský; Marián Lesný. 2019. "An Investigation of the Techno-Economic and Environmental Aspects of Process Heat Source Change in a Refinery." Processes 7, no. 11: 776.

Original article
Published: 25 June 2019 in Energy Efficiency
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Intending to contribute to the discourse about industrial energy efficiency and barriers to its improvement, deep insight into the scope and methodology and achievements of an energy audit on a Catalytic Naphtha Reforming Unit are provided. The audit of this particular unit was a part of the audit of the whole SLOVNAFT refinery in 2010–2012. The audit itself is the preparation of saving proposals’ implementation and post-implementation monitoring and targeting that lasted until spring 2016 covered in retrospective as the auditors were involved in all post-auditing phases as well. Several saving ideas emerging from the performed audit were rejected or have still not been implemented due to either technical issues or non-technical factors. Implemented proposals included improvement in the condensates’ management system, boiler feedwater preparation, and increased exploitation of the cogeneration potential. A cumulative 3-year benefit of over 600 k€ is reported which is close to the targeted value. The post-audit cooperation of auditors with the refinery’s staff enabled to define the non-technical barriers to saving proposals’ adoption that are of general nature. These included (1) short payback period requirement, (2) possibility of implementation of changes during the turnaround/general revisions, (3) conflicting relationships between local micro-economies of production units and the net-economy of the whole refinery, (4) internal processes and communication, and (5) personnel policy. Long-term cooperation, winning the trust and support of the staff and managers, and regular monitoring and targeting of implemented measures are seen as essential parts of sustainable industrial energy efficiency improvement in any industrial energy auditing.

ACS Style

Miroslav Variny; Marek Blahušiak; Otto Mierka; Štefan Godó; Tibor Margetíny. Energy saving measures from their cradle to full adoption with verified, monitored, and targeted performance: a look back at energy audit at Catalytic Naphtha Reforming Unit (CCR). Energy Efficiency 2019, 12, 1771 -1793.

AMA Style

Miroslav Variny, Marek Blahušiak, Otto Mierka, Štefan Godó, Tibor Margetíny. Energy saving measures from their cradle to full adoption with verified, monitored, and targeted performance: a look back at energy audit at Catalytic Naphtha Reforming Unit (CCR). Energy Efficiency. 2019; 12 (7):1771-1793.

Chicago/Turabian Style

Miroslav Variny; Marek Blahušiak; Otto Mierka; Štefan Godó; Tibor Margetíny. 2019. "Energy saving measures from their cradle to full adoption with verified, monitored, and targeted performance: a look back at energy audit at Catalytic Naphtha Reforming Unit (CCR)." Energy Efficiency 12, no. 7: 1771-1793.

Original article
Published: 18 June 2019 in Energy Efficiency
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The potential of modern regeneration boiler cold end and feedwater system integration with energy system of a paper mill is studied and measures for its better exploitation are proposed and assessed. Mathematical model has been developed, comprising material and heat balances, heat transfer equations, and steam turbine model. Its accuracy has been tested on the design and actual operation of a real system firing 70 t/h of dry solids. The simulation coped with design and measured data very well and also followed the operation changes performed in field tests excellently. Nine proposals aimed at real system efficiency improvement were assessed on the yearly benefit and simple payback period base, with yearly benefit resulting either from marginal fuel savings (scenario 1) or from condensing power production increase (scenario 2). Immediately applicable measures included deaeration at full steam pressure and heat load minimization in the first stage of the boiler feedwater regenerative heating—this novel finding contradicts the boiler design where full load regenerative heating is applied. Further measures increase the internal and external (available in paper mill) heat utilization. Their combination yielded either up to a 7 t/h internal steam consumption decrease (2.25% of nominal boiler steam output, scenario 1) or up to a 1.4 MW electricity production increase (2% of nominal steam turbine power output). Several of the proposed measures merit attention of boiler vendors and paper mills energy managers as viable tools towards low energy intensity pulp and paper mill industrial sector.

ACS Style

Miroslav Variny; Marek Blahušiak; Ján Janošovský; Michal Hruška; Otto Mierka. Optimization study on a modern regeneration boiler cold end operation and its feedwater system integration into energy system of a paper mill. Energy Efficiency 2019, 12, 1595 -1617.

AMA Style

Miroslav Variny, Marek Blahušiak, Ján Janošovský, Michal Hruška, Otto Mierka. Optimization study on a modern regeneration boiler cold end operation and its feedwater system integration into energy system of a paper mill. Energy Efficiency. 2019; 12 (6):1595-1617.

Chicago/Turabian Style

Miroslav Variny; Marek Blahušiak; Ján Janošovský; Michal Hruška; Otto Mierka. 2019. "Optimization study on a modern regeneration boiler cold end operation and its feedwater system integration into energy system of a paper mill." Energy Efficiency 12, no. 6: 1595-1617.

Journal article
Published: 01 April 2019 in Acta Chimica Slovaca
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Propane-propylene mixture splitting by industrial conventional rectification incorporating a heat pump for energy intensity decrease was modeled in the Matlab environment. The constructed model was verified by comparing its results with operational data of a real C3 fraction splitting unit. As documented, increased product quality can be obtained at zero additional costs due to specific features of the system design. Process capacity and product purity limitations have to be considered in future C3 fraction production increase plans. Further compressor and its driving unit design features have to be incorporated in the calculation model to reliably assess the C3 fraction processing costs and provide a reliable tool for process operation optimization.

ACS Style

Miroslav Variny; Patrik Furda; Norbert Kováč; Otto Mierka. Analysis of C3 fraction splitting system performance by mathematical modeling in MATLAB environment. Acta Chimica Slovaca 2019, 12, 127 -135.

AMA Style

Miroslav Variny, Patrik Furda, Norbert Kováč, Otto Mierka. Analysis of C3 fraction splitting system performance by mathematical modeling in MATLAB environment. Acta Chimica Slovaca. 2019; 12 (1):127-135.

Chicago/Turabian Style

Miroslav Variny; Patrik Furda; Norbert Kováč; Otto Mierka. 2019. "Analysis of C3 fraction splitting system performance by mathematical modeling in MATLAB environment." Acta Chimica Slovaca 12, no. 1: 127-135.

Journal article
Published: 01 March 2019 in Civil and Environmental Engineering Reports
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A study on natural gas saving and emissions decrease in the public health care sector is presented. The analyzed hospital complex belongs to the largest ones in Slovakia and uses both hot water and water steam for heating purposes. Visual steam system inspection revealed serious inefficiencies, including steam venting, missing pipelines insulation and obsolete steam sources with dysfunctional blow-down system. Defined experiment with stepwise steam appliances shutdown enabled quantification of excess natural gas consumption due to these inefficiencies. Measures proposed for the solution of this state are inexpensive, with a short payback period. The expected natural gas savings amount up to 3200 MWh/year, which represents roughly 50% of the total natural gas consumption in the hospital complex.

ACS Style

Otto Mierka; Miroslav Variny; Ingrida Skalíková; Peter Sámel; Jan Kizek; Róbert Súth; Karol Nagy. Natural Gas Saving And Emissions Decrease In Public Health Care Sector – A Case Study. Civil and Environmental Engineering Reports 2019, 29, 102 -118.

AMA Style

Otto Mierka, Miroslav Variny, Ingrida Skalíková, Peter Sámel, Jan Kizek, Róbert Súth, Karol Nagy. Natural Gas Saving And Emissions Decrease In Public Health Care Sector – A Case Study. Civil and Environmental Engineering Reports. 2019; 29 (1):102-118.

Chicago/Turabian Style

Otto Mierka; Miroslav Variny; Ingrida Skalíková; Peter Sámel; Jan Kizek; Róbert Súth; Karol Nagy. 2019. "Natural Gas Saving And Emissions Decrease In Public Health Care Sector – A Case Study." Civil and Environmental Engineering Reports 29, no. 1: 102-118.

Journal article
Published: 31 January 2011 in Energy
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Both European and Slovak legislation seek to promote efficient energetic media production with the support of old facilities, revamping being one of the embedded means. Based on our cooperation with Slovak industry, we analyzed several gas turbine based revamp alternatives of an industrial central heat and power plant of a paper mill in Slovakia from the technical, economic and exergoeconomic point of view, the latter being not yet applied in Slovakia to such a complex problem. The proposed alternatives exhibit a 45–55% marginal electric efficiency. However, at the given electric energy and natural gas prices and due to high fix production costs, individual project economics cannot ensure an attractive payback period unless providing ancillary services extensively. Overall and marginal results of the steam exergoeconomic costing procedure indicate that the proposed revamp alternatives are not able to provide cheaper electric energy than the existing configuration but they can produce cheaper low pressure steam for industry. The presented analysis provides a scheme and methodology for Slovak industry to properly cost the energetic media production.

ACS Style

Miroslav Variny; Otto Mierka. Technologic, economic and exergoeconomic evaluation of proposed industrial heat and power plant revamp alternatives in an industrial company in Slovakia. Energy 2011, 36, 424 -437.

AMA Style

Miroslav Variny, Otto Mierka. Technologic, economic and exergoeconomic evaluation of proposed industrial heat and power plant revamp alternatives in an industrial company in Slovakia. Energy. 2011; 36 (1):424-437.

Chicago/Turabian Style

Miroslav Variny; Otto Mierka. 2011. "Technologic, economic and exergoeconomic evaluation of proposed industrial heat and power plant revamp alternatives in an industrial company in Slovakia." Energy 36, no. 1: 424-437.