Steam Supply Research Articles

Dynamic Analysis on Carbon Metabolism of the Northern Region of China Under the Background of Carbon Emission Trading Policy

The launch of the national carbon emissions trading market in China is a policy to carry out the Beautiful China initiative and to establish a low-carbon economic development system that promotes carbon emission and waste reduction. In order to detect the carbon metabolic processes of the pilot and nonpilot municipalities or provinces in the northern region of China， the theory of urban carbon metabolism and the methods of input-output analysis and ecological network analysis were introduced and used. The results showed that the direct carbon emissions of Beijing and Tianjin had decreased， but their embodied carbon emissions had increased since 2012. The direct and embodied carbon emissions of the pilot sectors in Beijing and Tianjin had the same trend； specifically， the emissions of the sectors of mining and washing of coal， extraction of petroleum and natural gas， and manufacture of non-metallic mineral products decreased significantly， but the sectors of production and supply of electric power and steam with high carbon emission increased. The same trend of the embodied carbon emission intensities of sectors with that of their embodied carbon emissions verified that the embodied added values were not growing with the promotion of the carbon emission trading market. Subsequently， the embodied carbon emission of the pilot sectors in all the municipalities and provinces of the northern region were all contributed mainly by the emissions embodied by a path length less than 6； therefore， it showed that more attention should be paid to the trade among sectors with a path length less than 6 and reducing their carbon emissions. Furthermore， from 2007 to 2012， products or service trading among sectors mostly concentrated on sectors within one municipality or province， and these products or services had the characteristics of low carbon emission. Since 2012， the integration development of the Beijing-Tianjin-Hebei urban agglomeration and the new regional economic patterns established in the northern region both promoted the trading across provinces and across sectors. This research is based on the background of the carbon emission trading policy and aims to build a methodology to identify the key actors and paths in a metabolic system. This could provide a scientific basis for regional policy implementation and regional long-term sustainable development.

Investigation on thermohydraulic characteristics of novel superheated steam supply system for low temperature nuclear heating reactor

In a new Chinese low temperature nuclear heating reactor (NHR) demonstration project, a novel superheated steam supply system was designed to meet new requests for the steam produced in the secondary circuit. Different from the previous version of NHR200-II, which used a vertical steam generator to produce saturated steam, this newly designed system features a preheater, a horizontal steam generator, and a superheater for generating superheated steam. Numerical simulation method was used to investigate the feasibility and thermal hydraulic characteristics of this novel superheated steam supply system. The simulation results verify the accuracy and reliability of the system design, showing that the three heat exchangers can operate in coordination under different power levels, and the superheated steam generated in the secondary circuit can meet the users’ requirements. The system also demonstrated a remarkable ability to recover from sudden disturbances within 13.64 % change of the secondary circuit mass flow rate or 2.39 % change of the secondary circuit temperature under full power condition. Besides, the system has a power adjustment ability of ±10 %, and the system can quickly return to the new steady state. RELAP5 simulation results can provide theoretical guidance for the subsequent experimental research of this novel superheated steam supply system.

СТРУКТУРНІ ЗМІНИ У ПРОМИСЛОВОСТІ УКРАЇНИ В УМОВАХ ВІЙНИ

Changes in the structure of Ukraine's industry that took place after the full-scale military invasion of Russia on the territory of Ukraine were studied. Sectors of industry whose share in the industrial structure has changed significantly have been singled out. It is noted that metallurgy became one of the sectors of industry that suffered the greatest losses as a result of the war. The conducted analysis shows that a significant share of metallurgical enterprises is located in the war zone. This caused a decrease in the volume of metallurgical industrial production for 2022 by 54.59%. The reduction in the volume of individual productions led to structural changes in the industry of Ukraine. Therefore, we can draw conclusions about the growing role of the supply of electricity, gas, steam and air conditioning in the industrial structure. As for the processing industry, against the background of emerging trends, the production of food, beverages and tobacco products, manufacture of wood products, paper production and printing activities, textile production, production of clothing, leather, leather products and other materials occupy an increasingly significant position. Taking into account the fact that our country has a well-developed raw material potential for these areas of processing, it is possible to assert positive prospects for the further development of the indicated segments of industry. However, over the last year, the dynamics of the volume of sold products was negative in all segments of the industry, except for textile production, production of clothes, leather, leather products and other materials. Structural changes in industrial products sold outside the country were studied. Critical directions of industrial production in Ukraine and possible prospects for the development of industrial potential in modern conditions have been established. We can generalize that the modern structural changes in the industry of Ukraine, on the one hand, arose under the influence of the war and are negative, since our country has lost powerful industries. And, on the other hand, despite the difficult political and economic situation of our country, the potential for new opportunities is developing.

Investigation of liquid hydrocarbons combustion under combined supply of steam and oxidizer-diluent gases

This research is devoted to the experimental determination of regime parameters of stable combustion of diesel fuel with combined supply of steam and oxidizer-diluent gases into the gas generation chamber. When using the system of forced supply of diluent gases and oxidizer into the burner device, the flame breakdown limits in the burner were determined. Average temperature profiles along the vertical axis of the burner were obtained for the found modes of stable combustion of diesel fuel. The addition of diluent in the form of nitrogen or carbon dioxide to primary air leads to a significant decrease in the maximum temperature values.

Manufacturing industry potential of the Kyrgyz Republic in Eurasian economic integration

The Kyrgyz Republic, as a developing country with a socialist past, has great opportunities for further economic development. An important factor to consider is the growth of the manufacturing industry, which highlights the significance of analyzing this sector within the country. This study centers on the potential contribution of the Eurasian Economic Union (EAEU), of which Kyrgyzstan is a constituent, towards the advancement of this industry. The research aimed to evaluate the current manufacturing capacity of the Kyrgyz Republic in the industrial sector and to comprehend the influence of the EAEU on industry growth. The main methods that were used during the writing of the research were analysis, forecasting, abstraction, and historical analysis. The work analyzed the industrial sector of Kyrgyzstan within the framework of its integration into the EAEU. The research assessed the historical background of Kyrgyzstan’s accession to the EAEU and the subsequent harmonization of national legislation with the provisions and requirements of the union. In addition, data comparing the industrial production and growth rates of Kyrgyzstan, Armenia, and Kazakhstan have been presented, highlighting notable trends and differences. The work examines specific components of the manufacturing industry of the Kyrgyz Republic, the manufacture of food, beverages, and tobacco products; rubber and plastic manufacture, and non-metallic mineral goods; manufacturing of basic metals and metal products (excluding machinery and equipment); and supply of electricity, gas, steam, and conditioned air. It also talks about the manufacturing sector's importance in Kyrgyzstan, current trends, and possible future improvements, and it enables the assessment of the country's involvement in the EAEU.

The Impact of the Carbon Footprint in European Loans of the Economic Activities

The transition to a low-carbon economy has interested academics and policymakers recently. Our goal is to develop a preliminary analysis of the transition risk of the European financial system and individuate the importance of the environmental aspect in the loans received by statistical classification of economic activities in the European Union (NACE Sectors). The study defines two indicators that identify the transition risk the EU bears and the “carbon footprint of the loan” (CFL) that Europe presents through the loans granted to the various economic sectors. In addition, it analyzes the possible interactions that influenced the value of loans. In particular, the paper puts as the dependent variable the loans and, as independent variables, the Value Added (VA) by each NACE sector, the carbon footprint of loans, GreenHouse Gas emissions, environmental taxes, and economic growth. The groups “D. Electricity, gas, steam and air conditioning supply” plus “E. Water supply, sewerage, waste management and remediation activities” result to be, simultaneously, the sectors with the higher risk transition and CFL. Besides, the results show that the VA and CFL variables are statistically significant. The first highlights the strategic importance of having better performance and economic development, which allow for obtaining higher loans. The second variable underlines the ever-increasing importance of environmental issues and how the authorities are attentive to the provision of financing based on the polluting capacity of those “funded”. From this, we can deduce the ever-increasing importance of renewable energy for reducing greenhouse gases (European objective of climate neutrality by 2050) and reducing dependence on fossil fuels.

Multi-objective optimization of thermal power and outlet steam temperature for a nuclear steam supply system with deep reinforcement learning

The nuclear steam supply system (NSSS) is a critical component of a nuclear power plant that produces steam for electricity or cogeneration. However, the performance of current control strategies in the NSSS is limited since the coupling in the system is too complex and non-linear to be modeled precisely. Thus, there is an urgent need to study the model-free optimization method of NSSS. Motivated by this, this article proposes a novel multi-objective optimization approach based on deep reinforcement learning (DRL). With a hierarchical structure, the proposed method improves the response performances of both thermal power and outlet steam temperature by dynamically adjusting the reference values of existing proportional–integral–differential (PID) controllers within NSSS. This structure combines the stability of PID’s closed-loop control and the optimization capabilities of DRL for a safe and efficient operation. Moreover, a safe DRL method with an event-triggered mechanism is proposed to further ensure safety throughout the optimization process. The numerical simulations demonstrate the effectiveness and superiority of the proposed method, which results in significant improvements in the transient response compared to traditional PID controllers.

Techno-economic analyses of solar thermal process heat integration at South African beverage producers

South Africa's industrial sector relies primarily on coal and gas to meet process heat requirements (700–750 petajoules per annum). Much of this energy is used to fire steam boilers operated at less than 200 °C. This study determines the viability of solar thermal technologies as a replacement for fossil fuels for the supply of steam in large beverage facilities in South Africa. The Gauteng and Western Cape provinces are considered, which account for two-thirds of South Africa's beverage production. The sizing of collector fields and potential solar fractions are determined using typical ready-to-drink beverage packaging hall energy requirements. The cost of heat from parabolic trough collector systems is modelled using quasi-dynamic simulations in Polysun, and heat storage configurations are optimised. This study demonstrates that solar thermal projects would be viable alternatives to heavy fuel oil, diesel, gas, and even coal - should the cost of coal remain above US$250 /tonne (2020 real-term values). Transition to solar thermal energy for process heat in this sector is thus strongly recommended.

CRITERIA AND CONDITIONS OF THE INTER-CIRCUIT THERMODYNAMIC INSTABILITY OF THE NPP’S MODERNIZED TURBINE SYSTEM

The original method of determining the criteria and conditions of inter-circuit thermodynamic instability in the modernized system "steam turbine - regeneration system with absorption heat pumps" is presented. This was developed through a thermodynamic analysis of the effect of independent fluctuating deviations from equilibrium in both the wet vapor flow at the absorption heat pump inlet and the measured pressure in the absorption heat pump/low pressure mixing heaters. Unlike known approaches to modeling thermodynamic processes, the thermodynamic model of the developed method takes into account the influence of fluctuating deviations from the equilibrium state of thermodynamic parameters, which determine the criteria and conditions of interloop thermodynamic instability. Based on the analysis of the received criteria and conditions, it was established that the main cause of inter-circuit thermodynamic instability in the modernized system "steam turbine unit — a regeneration system with absorption heat pumps" is determined by the incompleteness (inertia) of heat-mass exchange and hydrodynamic processes during fluctuating deviations from the equilibrium state of thermodynamic parameters. Prevention of the conditions for inter-loop thermodynamic instability in the modernized system "steam turbine unit — a regeneration system with absorption heat pumps" can be ensured by installing flow controllers in the wet steam supply circuits from the high-pressure cylinder of the turbine to the absorption heat pumps, and absorption heat pumps in mixing heaters low pressure to maintain a constant pressure in absorption heat pumps and low pressure mixing heaters. It is also necessary to consider that the modernization of the "steam turbine unit — a regeneration system with absorption heat pumps" system can affect the performance and conditions of inter-loop thermodynamic instability of "neighboring" systems. These issues determine the need for further analysis of the validity of the modernization of the "steam turbine unit — a regeneration system with absorption heat pumps" systems.

Моdern heat and steam supply systems of industrial enterprises using deep utilization of the technological steam energy potential

Steam supply systems of industrial enterprises, as a type of heat supply system, are a large consumer of primary energy in national energy balances. In turn, due to the specificity of thermodynamic steam processes, steam supply systems of industrial enterprises in practice have significant unused potential of secondary energy resources (SEP). Modern steam supply systems should be built exclusively when evaluating their exergetic efficiency, which will make it possible to evaluate the effectiveness of such systems grossly in all elements of the life cycle of the project: energy, economic, ecological and even social. The article shows modernized thermal schemes of steam supply systems, for which it is possible to achieve additional electrical power at the level of 135-250 kW/(kg/s) when devices with a relative internal efficiency of up to 60-70 % are operating. In combination with an increase in the percentage of condensate return and the utilization of secondary energy resources (SRP), the increase in energy efficiency of the system is 2-4 %, and the absolute value of exergetic efficiency is 16-22 %, taking into account the exergetic efficiency of the boiler unit. Low-potential "tail" consumers: the heating system, the hot water supply system - increase the exergy efficiency of the steam supply system of an industrial enterprise by 0.2-0.6 % in the case of joining on the steam side of secondary boiling. Any processes of generating electrical energy are associated with obtaining a significant amount of thermal energy, and must be accompanied by its utilization; enterprises that use steam as an energy carrier (the same applies to energy enterprises such as thermal power plants and nuclear power plants) for the deep utilization of hydroelectric power plants must have thermal energy consumers in their composition, which can act as communal household consumers (if they exist), as well as new technological consumers of thermal energy.

SiRENE: A new generation of engineering simulator for real-time simulators at EDF

For Safety Assisted Engineering works, real-time simulators have emerged as a mandatory tool among all the key actors involved in the nuclear industry (utilities, designers and safety authorities). EDF, Electricité de France, as the leading worldwide nuclear power plant operator, has a crucial need for efficient and updated simulation tools for training, operating and safety analysis support.This paper will present the work performed at EDF/DT to develop a new generation of engineering simulator to fulfil these tasks. The project is called SiRENE, which is the acronym of Re-hosted Engineering Simulator in French. The project has been economically challenging. Therefore, to benefit from existing tools and experience, the SiRENE project combines:- A part of the process issued from the operating fleet training full-scope simulator.- An improvement of the simulator prediction reliability with the integration of High-Fidelity models, used in Safety Analysis. These High-Fidelity models address Nuclear Steam Supply System code, with CATHARE thermal-hydraulics system code and neutronics, with COCCINELLE code.- And taking advantage of the last generation and improvements of instructor station.The intensive and challenging uses of the new SiRENE engineering simulator are also discussed. The SiRENE simulator has to address different topics such as verification and validation of operating procedures, identification of safety paths, tests of I&C developments or modifications, tests on hydraulics system components (pump, valve etc.), support studies for Probabilistic Safety Analysis (PSA). etc. It also emerges that SiRENE simulator is a valuable tool for self-training of the newcomers in EDF nuclear engineering centers.As a modifiable tool and thanks to a skillful team managing the SiRENE project, specific and adapted modifications can be taken into account very quickly, in order to provide the best answers for our users' specific issues.Finally, the SiRENE simulator, and the associated configurations, has been distributed among the different engineering centers at EDF (DT in Lyon, DIPDE in Marseille and CNEPE in Tours). This distribution highlights a strong synergy and complementarity of the different engineering institutes at EDF, working together for a safer and a more profitable operating fleet.

Design and techno-economic analysis of a molten-salt driven energy conversion system for sustainable process heat supply

Storing off-peak cheap electricity from wind/solar farms for high-temperature heat storage in different mediums and using that for steam or high-temperature heat supply is a promising concept. A major issue for implementing high-temperature molten salt-based process heating systems is designing an appropriate heat exchanger system that can minimize the technical and operational risks and maximize the economic benefits. This study focuses on designing an optimal energy conversion unit based on this approach and conducts a techno-economic analysis of the developed system for a case study in Denmark to prove its proficiency. The system comprises a kettle boiler heat exchanger compatible with a high-temperature Sodium Hydroxide (NaOH) salt, and the case study is a cardboard factory demanding saturated steam at 10 bar, placed in the sustainable industrial business park GreenLab Skive. The results for the developed energy storage/conversion system with the given specifications and the salt are compared to an optimal design of the system when a conventional molten salt (solar salt mixture) is used. The results prove that the cost-effectiveness of the concept, in general, will be much dependent on the cost of charging electricity, and the system will only be promising if cheap off-grid electricity could be used during the whole charging process. It was found that the system with the benchmark salt NaOH for medium temperature use of ∼180 °C will be able to offer an LCOH of 67 €/MWh at an average cost of charging electricity of 63.6 €/MWh. The solar salt-cased energy conversion unit is less attractive economically but yet promising economically at cheap electricity charging rates.

Technical-Economic Analysis of Energy Efficiency Solutions for the Industrial Steam System of a Natural Gas Processing Plant

Steam, which is primarily employed as a heat transfer medium in process plants, is one of the most widely utilized energy carriers in the industrial sector. One of the factors that affects the cost of steam is how well the condensate collection, steam supply, and return systems of industrial steam systems perform. In a case study, the steam systems of a natural gas processing plant were simulated. The amount of demineralized water loss and, consequently, the identification of various solutions to improve the system were analyzed. The whole steam system was simulated using the MEASUR software platform (v 1.2), and by placing the operational information of the steam system, it was possible to create a baseline for the system, model saving solutions, and finally, provide a technical and economic evaluation of the solutions. Due to the high loss of steam condensate in the SRU steam system (more than 3000 kg per hour), solutions to improve the energy efficiency of the SRU steam system in the form of a maximum recovery of steam condensate (replacement of defective steam traps, redesign of the low-pressure condensate collection network, and high-pressure waste condensate collection) were evaluated with two price assumptions of current energy prices and real prices (the energy saving value of one cubic meter of natural gas is equal to 13 cents). The results show that, for current prices, the investment return period will be between 11.8 and 3.8 months. Moreover, in the main steam system of the refinery (unit 9200), there are three solutions: replacing and repairing defective steam traps, installing an expansion turbine instead of a steam pressure relief valve (PRV), and other solutions (including increasing boiler efficiency, automatic control of the boiler, and energy recovery boiler blowdown) under two price assumptions, the current and real prices of natural gas and demineralized water, were evaluated, and the modeling results show that the investment return period for each of the above solutions at the current prices is 10.2, 186, and 13.3, respectively. The investment return period is based on assuming real fuel and BFW prices are equal to 2.0, 37.6, and 1.7, respectively.

Coordinated control of mHTGR-based nuclear steam supply systems considering cold helium temperature

For industrial energy systems, there commonly exists coupling effect amongst those under-controlled process variables. Coordinated control of energy system enhances the operation performance by fully using the coupling effect positive to stabilization. Nuclear steam supply system (NSSS) module is the central of every nuclear plant, and the coordinated control of NSSS module is important for the stable, reliable and efficient operation of nuclear plants. Currently, the process variables considered in developing NSSS coordinated control strategies (CCSs) are mainly neutron flux, steam temperature as well as hot or average primary coolant temperature. Although cold primary coolant temperature, i.e. the primary coolant temperature at reactor inlet, reflects the heat balance between primary and secondary loops, it still not considered in developing CCS for NSSS modules. The modular high temperature gas-cooled reactor (mHTGR) uses helium as primary coolant and graphite as both moderator and structural material. Due to its inherent safety feature and high temperature, the mHTGR can be applied as a heat source driving industrial processes for power generation, chemical production and etc. To further improve the operation performance of mHTGR-based NSSS module, a passivity-based CCS is newly proposed by considering cold helium temperature. The sufficient condition for asymptotical closed-loop stability is given, and numerical simulation results in the cases of power stepping of 10 % reactor full power (RFP) as well as power ramping of 50%RFP and 5%RFP/min show that the control performance can be effectively improved.

Analysis of the Occurrence of Combustion Failure in the Steam Boiler at KM. Nggapulu

The availability of steam is crucial for the smooth operation of devices requiring hot steam. The operational activities of a ship can be hindered if the production of hot steam is insufficient due to problems arising from inadequate maintenance or other reasons, leading to the failure of combustion in the steam boiler. This research aims to identify the factors influencing the failure of combustion in the steam boiler on KM Nggapulu, to understand the consequences of the combustion failure in the steam boiler on KM Nggapulu, and to ascertain the measures taken in the event of combustion failure in the steam boiler on KM Nggapulu. The research method employed in this thesis is qualitative. The data sources include primary and secondary data. Data collection techniques encompass observation, interviews, and documentation, ensuring the validity of the data. Based on the research conducted, the following conclusions can be drawn: The causes of combustion failure include irregular implementation of the Planned Maintenance System (PMS), contamination of main burner components (automizer, electrode, solenoid valve), clogged exhaust gas pipes due to soot, excessive air composition in the furnace due to exhaust gas pipe blockage, poor fuel quality, and irregular cleaning practices. The impacts of boiler combustion failure involve operational difficulties for systems dependent on hot steam, inadequate hot steam supply for passenger or crew accommodation, and viscosity issues in MFO (Marine Fuel Oil) due to inadequate hot steam. Remedial actions that can be taken include checking and maintaining the automizer, inspecting and maintaining the main burner (electrode and nozzle), cleaning the fuel heater, replacing the solenoid valve, reducing fuel viscosity, and cleaning the steam boiler exhaust gas duct.

Analysis of Causes of Combustion Failure in Burner Incinerators at MT. JS INEOS INNOVATION

Abstraction-Incinerator is an auxiliary machine designed as the main combustion chamber to burn wasted oil after going through the heating process in a sludge incinerator tube. The use of the incinerator on the ship aims to burn the waste on the ship and also burn dirty oil. Based on the author's research, the operation of the incinerator on board is still not optimal due to the failure of the combustion in the incinerator burner. This study aims to find out the causes and efforts to solve the problems raised by researchers, namely combustion failure in the incinerator burner at MT. JS Ineos Innovation
 This study used a descriptive qualitative method. By using fishbone analysis techniques, researchers identified the factors and efforts made related to combustion failure at the Incinerator burner at MT. JS Ineos Innovation. Source of data taken from primary and secondary data. Data collection was carried out by interviews, observation, documentation, and literature study which was carried out during the research.
 Based on the research results, it can be concluded that combustion failure in the incinerator burner is caused by several factors, including a dirty burner nozzle, damaged steam valve, decreased steam supply from the steam service line, and jammed piston valve in the sludge dosing pump incinerator. Efforts made to overcome the occurrence of combustion failure at the incinerator burner are carrying out cleaning of the incinerator burner, carrying out maintenance or replacement of the steam valve, increasing the steam intensity from the steam service line to the inlet heater incinerator, and carrying out maintenance and repair of the piston valve in the sludge. dosing pump incinerator.

IMPACT OF REALIZED INVESTMENTS IN NEW FIXED ASSETS ON GROSS DOMESTIC PRODUCT IN SERBIA

The research subject is the analysis of the impact of the value of realized investments in new fixed assets on the gross domestic product (GDP) of Serbia in the period from 2012 to 2021. The research was conducted with the aim of determining which economic activity, according to the value of realized investments, contributes the most to the creation of the value of Serbia’s GDP. The defined goal was realized by applying the multiple regression method, and the starting model contained the value of realized investments in four activities, which are: manufacturing; electricity, gas, steam and air conditioning supply; transportation and storage; agriculture, forestry and fishing. The occurrence of multicollinearity between independent variables was checked by the tolerance coefficient, VIF coefficients and Eigen values, and their values indicate the presence of weak multicollinearity, which is a consequence of the impact of realized investments in agriculture, forestry and fishing. The result of the set regression model shows that the greatest contribution to the creation of Serbia’s GDP is made by the realized investment value in the electricity, gas, steam and air conditioning supply (Standardized Beta Coefficients 0.687, Sig. = 0.012).

UNDERSTANDING THE CARBON INTENSITY OF SOUTH KOREA’S EXPORTS: A MULTIPLICATIVE STRUCTURAL DECOMPOSITION ANALYSIS

Despite the large and growing role of exports in Korea’s carbon emissions, they have been largely overlooked in Korea’s carbon neutrality strategy. With this in mind, we analyze Korea’s aggregate emission intensity of exports (AEIE), an indicator of the environmental efficiency of exports, which decreased from 1.37[Formula: see text]Kt/$M to 0.74[Formula: see text]Kt/$M during 2000–2014. Using the multi-regional input-output model and two-stage multiplicative structural decomposition analysis (MSDA), we uncover drivers of changes in the AEIE. Analysis of bilateral AEIE shows that exports to developed countries had a large impact on the decline while exports to developing countries have risen in importance. MSDA shows that the carbon intensity effect contributed most to the decline but that trade in intermediate goods and trade in final goods were also important. At the sectoral level, manufacturers of basic metals, electricity, gas, steam and air conditioning supply and transportation sectors were shown to be important drivers of the decline in the AEIE. As the first study to analyze the drivers of Korea’s AEIE, this paper suggests various abatement policies to help achieve the goal of carbon neutrality by 2050.

Techno-economic optimization and Nox emission reduction through steam injection in gas turbine combustion chamber for waste heat recovery and water production

Considering the persistent human need for electricity and fresh water, cogeneration systems based on the production of these two products have attracted the attention of researchers. This study investigates a cogeneration system of electricity and fresh water based on gas turbine (GT) as the prime mover. The wasted energy of the GT exhaust gases is absorbed by a heat recovery steam generator (HRSG) and supplies the superheat steam required by the steam turbine (ST). In order to produce fresh water, a multi-effect desalination (MED) system is applied. The motive steam required is provided by extracting steam from the ST. In order to reduce the environmental pollution of this cogeneration system, the steam injection method is proposed in the GT's combustion chamber (CC). This system is optimized by a multi-objective optimization tool based on the Genetic Algorithm (GA). The design variables include pressure ratio of compressor (CPR), inlet temperature of gas turbine (TIT), steam injection mass flow rate in the CC, HRSG operating pressure, HRSG evaporator pinch point temperature difference (PPTD), steam pressure of the MED ejector, ejector motive steam flow rate, number of MED effects, and return effect. The goals are to minimize the total cost rate (TCR), which includes the cost of initial investment and maintenance of the system, the cost of consumed fuel, and the cost of disposing of CO and NO pollutants, as well as maximizing the exergy efficiency. In the end, it is observed that the steam injection in the CC leads to the reduction of the mentioned pollutant index, and it is proposed as a suitable solution to reduce the pollution of the proposed cogeneration system.

Modification of Misfit-Layered Cathode Materials for Improving Electrocatalyic Activity in Reversible Protonic Ceramic Cells

The demand for sustainable regeneration energies such as solar and wind has been continuously increasing by the rise of environmental issues. However, several major technical issues such as intermittent electricity production and high system construction cost are major obstacles to large-scale commercialization for regeneration energies [1]. Reversible protonic ceramic cells (RPCCs) can be an alternative choice because of their high efficiency, long-term durability at intermediate temperatures, and bifunctionality for producing both hydrogen and electricity in an electrochemical device [2]. Until now, perovskite-structured cathode (air/steam electrode) materials have been in spotlight due to their fast oxygen reaction kinetics in RPCCs [3]. However, in spite of their high electrocatalytic activity for oxygen electrode reactions (oxygen evolution and reduction), low phase stability in humid atmospheres, thermal expansion mismatch to common proton electrolytes, and relatively low proton conductivity of RPCCs are still major obstacles to enter the era of hydrogen economy [4, 5]. Hence, we demonstrate novel misfit-layered structure Ca3Co4O9+δ (CCO)-based materials to overcome these technical issues with superior catalytic activity for high performance RPCCs. The thermal expansion coefficient value of CCO is 10-12×10−6 K−1, which is relatively similar to that of the BaCeO3-based proton electrolytes, implying that the CCO-based materials are thermo-mechanically stable during cell operations [6]. In addition, the needle-like morphology of the CCO-based materials is quite valuable in the supply of steam (or air) to the catalytic active sites and elimination the water produced by the electrochemical reaction. Furthermore, with the doping of alkali metal ion (Li, Na, and K) into Ca-site, CCO generates extra charge carrier species with the modified Co oxidation state. This triggers the proton uptake and diffusion properties of CCO-based materials with the improved electrical conductivity. As a result, 5 mol% Na-doped CCO-cell shows exceptionally high performance in both protonic ceramic fuel cell and electrolysis cell modes for RPCCs.