Steam Generation Unit Research Articles

Novel sea water desalination unit utilizing solar energy heating system

A conventional parallel cross feed flow multi-effect desalination plant was simulated and optimized by the use of multi-goal algorithm MATLAB language programming together with engineering equation solver. An analysis of the overall performance of the plant was executed. A new design of solar desalination plant inclusive of solar parabolic collectors, steam generator, and MED unit has been proposed to commute the conventional plant. Further, an implementing was carried out on the subject of oblique steam production true more than one thermal oil which include THERMINOL VP1, THERMINOL 66, THERMINOL 59, THERMINOL SP, THERMINOL 55 and DOWTHERM A in addition to water. Via the simulation, it became clear that THERMINOL VP1 had 1.025% greater desalinated water than others. Additionally, the operation cost of distillate production by the usage of mazut or natural gas is a lot extra than using solar energy.

One-dimensional design approach to integrated steam generator with helical-coil tube bundles for a sodium-cooled fast reactor

A potential of a sodium-water reaction in a steam generator (SG) has been known to result in a drastic increase of the capital cost of a sodium-cooled fast reactor (SFR). This is mainly because an essential risk of potential sodium-water reaction (SWR) at the pressure boundary between water/steam and liquid sodium in the SG unit of an SFR. To prevent the SWR event during the whole plant lifetime, the novel design of an integrated steam generator (ISG) concept was proposed and its creative thermal-hydraulic design approach was developed as well. The ISG design for an SFR is based on the concept of combined SG unit with an intermediate heat exchanger (IHX) to make the chance to contact of water vapor with liquid sodium very few. However, it requires far more heat transfer area than that of an existing design with both IHX and SG unit due to the lower thermal conductivity of an alternative intermediate heat transfer medium. In order to minimize the heat transfer area of ISG, its thermal-sizing analyses using three representative design parameters, such as the number of tubes, tube bundle arrangement, and tube inclination angle, were conducted by a one-dimensional analysis code. In this study, the optimal design condition of the integrated steam generator for the reference plant of KALIMER-600 was obtained and the required heat transfer area of the ISG unit was compared to that of the existing SG unit and IHX unit in KALIMER-600. It was found that the proposed ISG design requires 2.25 times of heat transfer area to transport the same amount of heat as the conventional two heat exchanger system.

Energy, exergy, and environmental (3E) assessments of an integrated molten carbonate fuel cell (MCFC), Stirling engine and organic Rankine cycle (ORC) cogeneration system fed by a biomass-fueled gasifier

In this paper, a novel syngas-fed combined cogeneration plant, integrating a biomass gasifier, a molten carbonate fuel cell (MCFC), a heat recovery steam generator (HRSG) unit, a Stirling engine, and an organic Rankine cycle (ORC), is introduced and thermodynamically analyzed to recognize its potentials compared to the previous solo/combined systems. For the proposed system, energetic, exergetic as well as environmental evaluations are performed. Based on the results, the gasifier and the fuel cell have a significant contribution to the exergy destruction of the system. Through a parametric study, the current density and the stack temperature difference are known as the main effective factors on the plant performance. Meanwhile, dividing the whole system into three sub-models, i.e., model (1): power production plant including the gasifier and MCFC without including Stirling engine, HRSG, and ORC unit, model (2): the cogeneration system without ORC unit, and model (3): the whole cogeneration system, an environmental impact assessment is carried out regarding CO2 emission. Considering paper as biomass revealed that maximum value of exergy efficiency is 50.18% with CO2 emissions of 28.9 × 10−2 t.MWh−1 which compared to the solo MCFC system indicates 28.40% increase and 13.3 × 10−2 t.MWh−1 decrease in exergy efficiency and CO2 emission, respectively.

Energy-Exergy Analysis of Combined Reheating-Regenerative Rankine Cycle using Entropy Generation Principle

The growing attention towards the exergy analysis of thermal systems is identifying the cause of losses, to scale the process, and rectifying the components. In this paper, the thermodynamic (energy-exergy) analysis of combined reheating and regeneration based Rankine Cycle is carried out. The energy-exergy analysis has been established for the boiler, turbines, Feed heaters, condenser and pump majorly. The result of thermodynamic analysis is estimeted in terms of 42% of plant thermal efficiency, 70 % of steam generation unit efficiency (Economizer. Super heater), Maximum heat absorbed by economizer of plant as 39% is achieved, with 40TPH of coal consumption. Boiler, High Pressure Turbine, Intermediate Pressure Turbine, Super Heater have found best performance in analysis and Reheating-Regenerative rankine method improves 6-8% in thermal efficiency also. This analysis concluded that energy efficiency is greater than exergy efficiency which identifies the power plant utilities and further improvement for efficient power generation opportunities like waste heat recovery technology employment.

Thermo- economic evaluation of 300 MW coal based oxy-fuel power plant integrated with organic Rankine cycle

Oxy-fuel combustion is currently most potential technology to reduce carbon dioxide emission from coal based power plants. This work describes thermo- economic analysis of CO2 capture technology by assessment of detailed models of a 300 MW steam generation unit, an oxygen separation unit and shock wave CO2 compression unit that are developed using Aspen HYSYS v9. The overall efficiency of the oxy-fuel combustion plant reduced by 10.98% due to implementation of air separation and CO2 sequestration systems. To reduce the efficiency penalty, the waste heat released at different portions of plant is used to boost an organic Rankin cycle for power generation. CO2 compression intercoolers and air separation unit coolers are two low grade heat sources which are utilized in ORCs. By recovering the wasted heats, the unit power consumption of oxygen production decreases from 227.3 to 214.2 kW h/t O2, power plant efficiency drop reduces about 1.51% and cost of electricity decreases from 67.03 to 64.94 €/MWh. The results indicate that proposed ORCs are thermodynamically and economically feasible to integrate with plant to increase the net efficiency.

A simultaneous optimization approach for efficiency measures regarding design and operation of industrial energy systems

Sustainability in industrial energy systems has to be increased to achieve climate goals. However, the share of batch processes in industry and changes of the product portfolio have increased. This makes it more difficult to establish sustainable and yet flexible energy supply systems. Current optimization methods for the synthesis of process heat supply systems do not consider all essential aspects. In this paper, optimization of internal heat recovery with heat exchanger networks and storage integration are carried out simultaneously considering operational constraints of the existing supply infrastructure. Furthermore, within this approach storage units can be considered for both heat recovery and load shifting of steam generator units. Necessary interfaces for coupling of operational constraints and design optimization were identified and the complexity of the combined problem was reduced by simplifications. The combined approach was compared to sequential implementation and proved to yield both economical improvements and more sustainable energy use.

Tsallis Entropy Segmentation and Shape Feature-based Classification of Defects in the Simulated Magnetic Flux Leakage Images of Steam Generator Tubes

Early detection of water or steam leaks into sodium in the steam generator units of nuclear reactors is an important requirement from safety and economic considerations. Automated defect detection and classification algorithm for categorizing the defects in the steam generator tube (SGT) of nuclear power plants using magnetic flux leakage (MFL) technique has been developed. MFL detection is one of the most prevalent methods of pipeline inspection. Comsol 4.3a, a multiphysics modeling software has been used to obtain the simulated MFL defect images. Different thresholding methods are applied to segment the defect images. Performance metrics have been computed to identify the better segmentation technique. Shape-based feature sets such as area, perimeter, equivalent diameter, roundness, bounding box, circularity ratio and eccentricity for defect have been extracted as features for defect detection and classification. A feed forward neural network has been constructed and trained using a back-propagation algorithm. The shape features extracted from Tsallis entropy-based segmented MFL images have been used as inputs for training and recognizing shapes. The proposed method with Tsallis entropy segmentation and shape-based feature set has yielded the promising results with detection accuracy of 100% and average classification accuracy of 96.11%.

Exergoeconomic analysis of lactic acid and power cogeneration from sugarcane residues through a biorefinery approach

The present survey was devoted to exergoeconomically investigating a lignocellulosic-based sugarcane biorefinery developed for cogeneration of lactic acid and power from sugarcane bagasse and harvesting residues, specifically brown leaves (trash). More specifically, this research was aimed at identifying the hotspots of the cost losses in the developed biorefinery. Exergoeconomic parameters including irreversibility-related cost rate, component-related cost rate, total cost rate, relative cost difference, and exergoeconomic factor were determined for all the nine subunits of the biorefinery. In addition, two new exergoeconomic variables called “economic impact ratio” and “economic modification requirement index” were introduced and elaborated throughout this study. After obtaining cost balances for all subunits of the biorefinery, product and fuel rules were considered according to Specific Exergy Costing (SPECO) approach for determining the unit exergoeconomic cost of all streams involved in the process. The unit exergoeconomic costs of lactic acid, power, steam, and liquid digestate were found to be 8.55, 15.61, 15.61, and 17.96 USD/GJ, respectively. The highest total cost rate was determined at 3715.86 USD/h for the steam generation unit, accounting for 43.73% of the total cost rate of the biorefinery. The lactic acid synthesis unit stood in the next rank, contributing to 20.49% of the total cost rate of the system. Overall, attempts to promote the exergoeconomic performance of the biorefinery must mainly focus on minimizing the irreversibility-related cost rate of the steam generation unit.

Nuclear Power Plants for the Icebreaker Fleet and Power Generation in the Arctic Region: Development Experience and Future Prospects

The technical characteristics of a power series of reactor installations developed at Afrikantov OKBM are presented. The technical qualities making facilities equipped with modern ship reactor installations commercially attractive are shown to have undergone evolutionary improvement. First and foremost these are facilities for universal nuclear icebreakers under construction and an icebreaker in the design stage. Designs of optimized floating and ground-based power-generating units with improved user qualities are being developed on the basis of the experience gained in the development of a floating nuclear heat-and-power plant based on the Akademik Lomonosov floating power-generating unit. Promising reactors of the type RITM are used in these designs. They differ fundamentally from the block-type units by the integral steam-generating unit, heightened energy resource, and long intervals between refuelings, which are possible owing to the innovative core with metal-ceramic fuel and new structural materials. The possibility of significantly increasing the resource of the new reactor installations is confirmed by its stepped increase on operating nuclear ships and by scientific-technical studies.

Low emission flash-binary and two-phase binary geothermal power plants with water absorption and reinjection of non-condensable gases

The power production from geothermal resources with a high content of non-condensable gases (NCG) is concerning an increasing number of regions and may affect the sustainability relating to geothermal projects. The selection of an emission abatement system based on water absorption and reinjection of NCG back to the reservoir could solve the environmental impact, yet it implies significant power output penalty and water demand, as demonstrated in a recent paper by the authors (Manente et al., 2019) focused on the retrofit of existing flash steam power stations. A reconsideration of the plant design could result in a better integration with the absorption and reinjection section and finally reduce the associated requirements. To address this point, two “greenfield” plant layouts are investigated in this paper for utilization of a high enthalpy liquid dominated reservoir, where the single flash steam generation unit is complemented or even totally replaced by air cooled binary cycle units. The first layout is an “integrated flash-binary” plant based on a backpressure steam turbine and a bottoming ORC system, whereas the second layout consists in a “two-phase binary” plant. The performance of the two novel layouts is compared against that of a brownfield layout, first proposed in Manente et al. (2019), based on an existing single flash plant retrofitted with the absorption and reinjection system, using a consistent set of assumptions. The results show that the net power output remains almost unaltered because in the novel layouts the lower parasitic loads for gas compression counterbalance the lower production dictated by the air-cooled system and the irreversibility in the heat transfer between geothermal fluid and organic fluid. Thus, due to the better integration between power block and emission abatement section the net power output penalty of the novel layouts is contained within 2%. On the other hand, the hydrogen sulfide and carbon dioxide abatement efficiencies markedly increase as the removal of the cooling tower eliminates the secondary gaseous emissions and makes the entire steam condensate available for NCG absorption. In the integrated flash-binary plant design the overall H2S and CO2 abatement efficiencies reach 99% and 90%, respectively, without any external water demand, provided that measures are taken for a controlled precipitation of silica and other minerals from the geothermal brine prior to using it for NCG absorption.

Performance modeling and assessment of maintenance priorities for steam generation unit of a sugar plant

Purpose The purpose of this paper is to deal with the performance modeling and assessment of maintenance priorities for steam generation unit of a sugar plant. Design/methodology/approach The unit comprises of four subsystems, i.e., Bagasse elevator, Bagasse carrier, boiler and feed pump. The Chapman–Kolmogorov equations are generated on the basis of transition diagram and further solved recursively to obtain the performance modeling with the help of normalizing condition using the Markov approach. Findings Decision matrices are formed with the help of different combinations of failure and repair rates of all subsystems. The performance of steam generation unit is evaluated in terms of availability levels depicted in decision matrices and plots of failure rates and repair rates of various subsystems. The maintenance priorities of various subsystems of steam generation unit are decided on the basis of effect of failure and repair rates of subsystems on the availability of steam generation unit. The key finding is that the boiler subsystem is the most critical subsystem and hence should be kept on top maintenance priority for performance enhancement of the steam generation unit. Originality/value The acceptance of both performance modeling and maintenance priorities decision by the management of sugar plant will result in the enhancement of unit availability and reduction of maintenance cost.

Separating photo-thermal conversion and steam generation process for evaporation enhancement using a solar absorber

Solar steam generation is an effective method combining solar energy utilization with water treatment. Photo-thermal conversion and steam generation are typically integrated to enhance the evaporation process, which have wide applications in seawater desalination, waste water treatment, sterilization and power plant fields. However, the photo-thermal enhancement for different evaporation areas remains unclear, and there are a number of important issues for membrane process (e.g., blockage of pore structures and contamination of nanoparticles). To overcome these issues, we herein propose a separating design involving a C-TiO2 absorber and a polyvinyl alcohol fiber material as the photo-thermal and steam generation units, respectively. A C-TiO2 absorber with good spectral and photo-thermal conversion characteristics was prepared. And the evaporation enhancement effect was investigated with different evaporation areas by experiments and simulations. The equivalent evaporation rate reached the maxima with the evaporation area and decreased thereafter for this separating design. The optimum behavior was achieved when the evaporation region area to photo-thermal area ratio of ca. 2.06, providing guidance for large-scale use. These results can be explained in terms of the changed thermal gradient generated between the center C-TiO2 film and the evaporation region. The design achieved equivalent evaporation rates and evaporation efficiencies of 1.24 kg·m−2·h−1 and 77.83%, respectively, paving the way for the further improvement of solar steam generation processes.

Experimental Investigation and Mathematical Modelling of Pressure Response for Steam Generator

Cold startup of boiler is the process of boiler operation with water at ambient temperature and pressure with all intake and discharge valves are fully closed to permit fast development of pressure. A mathematical model is developed to estimate the pressure response during cold startup of a perfectly insulated steam generator unit. A commercial type pressure switch is used in this unit to control and maintain the desired set point of the steam operating pressure. This mathematical model assume that the thermal properties of the supplied liquid water are temperature dependent. It is based on a novel Pressure Marching Technique that is coded using a FORTRAN language computer program. The maximum percentage error of (8.24 %) was obtained when comparing the predicted results of the mathematical model with the measured values obtained from the experimental test that was done using a (2 kW) electric steam generator unit with a volume of (30 litter) and maximum operating pressure of (8 bar). In addition, the same behavior of the predicted results was obtained when compared with results of a previously published article. It was found that the time constant of the pressure control system is directly proportional with its operating pressure set point and with the volume of the steam generator and its void fraction. A (50%) increase in the pressure set point will increase the time constant by (66.16%). Increasing the boiler volume by (166.667%) will increase the time constant by (166.677%) and increasing the boiler void fraction by (150%) will increase the time constant by (23.634%). The time constant is inversely proportional with the heating power of the steam generator. A (100%) increase in the heating power will decrease the time constant by (50%). The time constant is independent of the initial water temperature. Also, it was found that the time delay to start water evaporation is directly proportional with the volume of the steam generator. A (166.667%) increase in boiler volume will increase the time delay by (166.65%). The time delay is inversely proportional with the initial water temperature and with the heating power and void fraction of the steam generator. A (38.889%) increase in the initial water temperature will decrease the time delay by (8.882%). Increasing the heating power by (100%) will decrease the time delay by (50%) and increasing the boiler void fraction by (150%) will decrease the time delay by (16.665%). The time delay is independent on the operating pressure set point.

Impression creep testing for evaluation of grade 22 ex-service hot reheat piping seam weld

U.S. electric power production is significantly dependent on the operation of coal-fired steam generation units and a large majority of these units are reaching ages over 50+ years with concerns for operating component integrity and remaining life. This paper discusses a small sample testing technique (impression creep) that was used to estimate the remaining life of a hot reheat seam welded piping system that saw about 322,000 hours of operation at nominally 4170 kPa (605psig) and 538°C (1000°F) steam conditions. Two different life assessments using experimental impression creep data are discussed and findings compared to a previous preliminary study of the same piping system using operational data, reported measured piping thickness values (from UT measurements), and published creep rupture data. Impression creep tests were conducted in unaffected base metal, weld metal and the heat-affected zone. Impression creep rates of the various zones showed no creep mismatch. Minimal creep mismatch, proper design, fabrication and operation, combined with proper metallurgy have successfully demonstrated that even low-alloy seam welds can operate 300,000+ hours and still exhibit useful remaining life.

Automatic Alleviation of Overloads in Transmission Network by Generation Curtailment

For economic reasons, expansions of transmission networks are based on a compromise between capital cost and security of power system operation. At the same time, the power system must withstand typical highly likely contingencies. Various emergency state control systems, also called special protections, prevent emergencies following less likely contingencies. This paper describes overloads emergency state control (OLEC) used for the alleviation of overload in transmission networks near a power plant. Such control uses the functions of automated power reduction of generating units and has been implemented for a large steam power plant. The OLEC presented here uses different methods of generation curtailment for steam generation units. A case study illustrates the efficiency of the proposed control method.

Energy and exergy investigation of a combined cooling, heating, power generation, and seawater desalination system

In the present paper, a combined cooling, heating and power and a multi effect desalination with thermal vapor compression system was used to simultaneously produce electricity, fresh water, refrigeration, and hot water for domestic use. In order to link the Brayton cycle to the water desalination and ejector refrigeration systems, a dual-pressure heat recovery steam generator unit was utilized. In this research, the considered system was analyzed in terms of exergy and energy under various operational conditions and also pollution generated by combustion process is determined. To consider the effects of design parameters on the efficiency of the system, a parametric analysis was further conducted to examine influences of such factors as compressor compression ratio, inlet temperature of turbine, vapor pressure entering into the desalination unit, and the number of desalination units on exergy and energy efficiencies of the cycle. The results indicated the capability of the proposed system for providing fresh water, power, cooling and heating loads of 85.57 kg/s, 30 MW, 2.03 MW and 1.11 MW, respectively. Finally, total exergy destruction and exergy and energy efficiencies of the cycle were obtained to be 55.82 MW, 36.03%, and 39.22%, respectively.

Development of mobile boiling system for turmeric ( Curcuma longa )

Abstract Turmeric boiling system based on convectional boiling technique had been developed to retain curcumin content up to highest possible level and reduce the cooking time. The whole system consists of steam generation unit and blanching vessel. The blanching vessel was modified to mobile boiling vessel which consists of a steam inlet, turmeric holding body (100 kg), safety valve, pressure release valve, pressure and temperature gauge, condenser, steam distribution unit having centre-mounted perforated pipe with blinded end to distribute the steam uniformly throughout the vessel and vessel holding stand with wheels. The blanching time, drying rate, drying time and heat utilization factor were quantified. The cooking time under the developed vessel for turmeric was found to be 10 min compared to 15 min under parboiling drum and 25 min under open steaming used by the farmers. The color values for samples obtained by cooking using the developed vessel was found to be with L = 53.74, a = 58.46 and b = 18.16.

An intelligent hybrid technique for fault detection and condition monitoring of a thermal power plant

• A Hybrid fault detection approach based on intelligent classifiers was proposed. • Experimental data during emergency shut-downs were employed. • Decision fusion technique was applied to combine the outlet of classifiers. • Fault detection prevented from undesired system trips. This study presents an application of intelligent fault detection system for recognizing abnormal conditions during transient operation of a steam generator unit. Unobserved dynamics of evaporator section have been caused multiple false alarms and boiler emergency shut-downs. In order to detect faulty conditions, four different classifier agents were employed in parallel. The experimental data from real system performances during system trips were collected to train and validate the intelligent classifiers. The outlet results of all classifiers were combined using Yager's rule of fusion in order to improve the reliability and accuracy of fault detection process. The performances of the proposed fault detection system were evaluated during the unit's load variations and at different scenarios as one or two classifier(s) failed to detect the correct situations. The obtained results indicated the capability and feasibility of the proposed technique in preventing from raising false alarms by early detection of abnormal conditions.

Cracking of superheater tube in a captive power plant

ABSTRACTA steam generator unit in a captive power plant of a heavy water plant reported fish-mouth failure in the secondary super heater bend. The operating pressure of the super heater is 105 kg cm−2 and temperature is 485°C. The super heater tubes made of 2¼Cr–1Mo ferritic steel is exposed to steam at a pH of 9.5–10.5 and conductivity less than 2 µS cm−1 in the inner surface and at the outer surface exposed to flue gas. It has been operational for last 25 years. Layered deposits were observed at the failed region which were iron oxides. The investigations revealed that outer surface which has flue gas environment showed thinning with oxide scale spallation taking place. The SEM studies showed that there was extensive precipitation of molybdenum sulphide and carbides in the microstructure resulting in preferential oxidation along grain boundaries. The excessive outer thinning of tube resulted in fish-mouth failure of the super heater tube.This paper is part of a supplementary issue from the 17th Asia-Pacific Corrosion Control Conference (APCCC-17).

Simulating combustion processes based on digital technologies

The thermal power plants (TPP) make a basis of power-generation industry of the majority of countries. The global growth of power consumption and the policy of energy-saving demand to increase the efficiency of plants operation, which is, among others, determined by the technical level of steam-generating units. The up-to-date digital technologies make it possible to assess the efficiency of boiler furnace operation at the stage of boiler unit designing, its reconstruction or retrofitting and upgrading. Developed in the article are the algorithm, mathematic model and computer program of calculating diffusion-kinetic process of combustion of D-grade Donetsk coal in the coal-dust flame of boiler Е-230-14,0-520. The assigned tasks have been solved by using theoretical methods of analysis, the capabilities of devices of computer-aided calculations have utilized for visualization of results. The considered digital approach to solving technical tasks makes it possible to meet the current and future challenges.