Steam Mass Flow Rate Research Articles

Dynamic modeling of a multi-effect vertical falling-film evaporator for water reuse in CSP plants

This work presents the dynamic modeling of a vertical multi-effect evaporator plant designed and manufactured for its installation at a commercial concentrating solar power (CSP) plant, within the framework of EU H2020 project SOLWARIS (Solving Water Issues for CSP plants). The model has been developed using Modelica computational language and implemented in Dymola® software environment. The results from the validation show a good agreement against the design data, obtaining relative errors lower than 5%. The dynamic response of the plant against external disturbances of the motive steam mass flow rate, feedwater mass flow rate and condenser pressure has been investigated. The main results reveal that increasing the motive steam flow rate by 5% produces a similar increment of the water recovered (5.2%), although the concentrate salinity is raised to an unsafe operation zone (106%) that could lead to scaling issues in the evaporators. The same effect occurs when the feedwater is decreased by 5% from its nominal value, causing a significant rise in the concentrate salinity (163%). In those cases, the simultaneous and proportional variation of the motive steam and feedwater mass flow rates allows maintaining the outlet concentrate salinity far from scale formation limits.

Numerical simulation of the thermal radiation and convective heat transfer characteristics of the second superheater in a coal-fired thermal power plant boiler

Superheaters are critical components in a coal-fired power plant because they sustain the highest tube wall (metal) temperature point in the boiler. The pressurized steam flowing in superheater tubes is mainly heated via the thermal radiation and convection from the combustion gas in the radiant zone. To prevent the bursting of superheater tubes caused by the high-temperature creep, corrosion, and thermal fatigue for proper plant operation and maintenance, accurately predicting complex heat transfer characteristics, estimating the local temperature, and assessing the heat flux of the superheater are essential. In this study, a computational fluid dynamics model of the boiler and the superheater in a coal-fired power plant was developed using radiation and turbulence models. The local metal temperature and heat flux of the superheater were evaluated by calculating the heat exchange between the combustion gas and pressurized steam flows in the tubes. The calculated values of the steam outlet temperature accurately matched the values measured using the equipment at the plant, and thermal radiation was confirmed to be dominant in the boiler. The metal temperature and heat flux of the superheater at the outermost heat transfer tubes, which receive the maximum thermal radiation, were larger than those of the superheater at the inner tubes. Therefore, the outermost tubes were determined to be under the most severe thermal conditions despite having a higher mass flow rate of steam. Additionally, the heat fluxes on the center lines of superheater tube panels were higher due to the large gap between the adjacent heat transfer tubes at the bent part.

Environmental impact assessment of a real geothermal driven power plant with two-stage ORC using enhanced exergo-environmental analysis

Geothermal driven power plants (GPPs) with two-stage ORC are mostly used in low-temperature geothermal fields around the World. The environmental impacts of these GPPs create a gap in the literature. In this study, enhanced exergo-environmental analysis for the GPP and its components is conducted as a case study. With the analysis, the component-related, exergy degradation-related, and pollution formation-related environmental impacts (EIs) are separated endogenous/exogenous and avoidable/unavoidable parts. In this way, detailed information about the interaction and improvement potential between components is acquired by using the recommended performance indicators. The results of the study show that for the enhanced exergo-environmental analysis, EI related to exergy destruction of components is predominated. In the traditional exergo-environmental analysis the total amount of EI is condenser with 1.386 Pt/h while in the enhanced one the highest avoidable-endogenous exergy destruction is condenser with 716 Pt/h. The value of EI which is caused by electricity generation is 0.108 Pts/kWh. The EI value of geothermal fluid is 11.8 Pt/GJ. The EI value of the plant's avoidable-endogenous pollution formation is 8 Pt/h. As the reason for this, the mass flow rate of the geothermal fluid steam and the amount of NCG gas in it are effective. Eventually, if the plant could be operated under enhanced analysis' operation conditions, the EI of released CO2 value can be reduced by 8.4% by carbon capture and storage. Thus, the details of the analyzes performed for the plant are expected to guide the researchers.

A new software program for monitoring the energy distribution in a thermal waste treatment plant system

The paper presents a novel system for monitoring the operation of a thermal waste treatment plant. The computer program is based on measurements of pressure, temperature, and mass flow rate of the working medium. The boiler efficiency is calculated using an indirect method. Thermal online calculations of the boiler combustion chamber make it possible to determine the heat flow rate to the evaporator. Based on the energy balance of the boiler evaporator, the superheated steam mass flow rate is determined, taking into account the mass flow rates of water injected into steam attemperators. By comparing the calculated and measured value of steam mass flow rate, the calorific value of the fuel fed is determined. The developed system enables monitoring of energy flow rates in individual elements of the power unit, taking into account losses in the boiler and turbine condenser. The following parameters are determined online, the efficiency of the boiler and the entire incinerator, heat losses in the boiler and the turbine condenser, as well as the heat flow rate, supplied to the municipal district heating system. By monitoring the plant operation, it is possible to adjust online the optimum excess air ratio.

Research on short term prediction method of thermal hydraulic transient operation parameters based on automated deep learning

Automated deep learning is a new development direction of deep learning based on automated machine learning. Its main purpose is to achieve the automated operation of deep learning algorithm design process from design, training, parameter adjustment and so on. Due to a large number of repeated operations such as parameter adjustment and optimization model, the algorithm design process relies heavily on designers and consumes a lot of design time. Based on the automated deep learning method, this paper designs a short term prediction method of thermal hydraulic transient operation parameters, which can achieve the whole design process hosting operation. This method only needs the designer to upload the data set to the prediction model to complete the algorithm design, and does not need the designer’s intervention in the whole process, so as to simplify the operation and save the design time. At the same time, quantum genetic algorithm and model agnostic meta learning are introduced to ensure that the algorithm is still reliable and effective when the data set is expanded and the prediction problem is more complex. And the algorithm can be porting and application on quantum computer. In order to verify the algorithm, the steam mass flow rate at the outlet of main steam pipe of steam generator and the water temperature at the bottom of pressurizer are predicted respectively after 1 s, 2 s, 3 s and 5 s. The calculations show that the maximum error of the prediction models is about 4%, and the average prediction time of a group of parameters is about 0.7 ms. The prediction model based on the combination of the above algorithms can be used to predict the change trend of thermal transient operation parameters in a short time and provide effective judgment basis for the reactor accident early warning.

The coupling process of steam condensation and falling film evaporation with non-condensable gas

For the steam condensation process inside a horizontal tube under small temperature difference, the operating parameters such as steam flow rate and temperature difference are narrowed in limited variation ranges to guarantee the high heat transfer performance. When the steam is mixed with non-condensable gas, the effective temperature difference shows more complexity compared with pure steam condensation. In this paper, the condensation process of the mixed steam in the tube cooled by the falling film evaporative seawater outside the tube is calculated with the steam mass flow rate of 2–9 kg/(m2·s), the evaporation temperature of the seawater of 50–70 °C, the total temperature difference of 2–4 °C and the inlet non-condensable gas (NCG) mass fraction of 1–4%. The mixed steam condensation heat transfer model combined with distributed parameter model is established and validated to couple the heat transfer on both sides of the tube. The local saturation temperature depression of the mixed steam condensation is divided into two factors, one caused by the flow resistance and the other caused by the non-condensable gas mass fraction. Both types of saturation temperature depression increase with the increase of the inlet non-condensable gas mass fraction. The mass flow rate and the temperature difference are found to have more significant impact on the total temperature depression on the saturation temperature. Besides, the saturation temperature is found to have no significant impact on the condensation heat transfer of the mixed steam. The mass flow rate corresponding to the maximum heat transfer of the heat transfer tube is presented.

Application of a high-order MP scheme to computation of multi-phase flows with heat and mass transfer

Reliable prediction of unsteady multiphase flows with mass changes, large density ratios, and complex flow features is very challenging due to the need to accurately resolve both complex interface deformations and steep gradients associated with material interfaces. This paper describes an application of our recently developed high-order monotonicity preserving (MP) scheme – a reliable and robust scheme for long-term computations of flows contain complex smooth structures interspersed with discontinuities (Ha and Lee, 2020) − to the solution of unsteady incompressible two-phase flows in the presence of heat and mass changes. The flow is governed by the multiphase Navier–Stokes equations, which comprises of the mixture continuity equation, the mixture momentum equations, the mixture energy equation, and the continuity equation for the individual phase. The numerical discretization is implemented on generalized curvilinear grids for facilitating flow simulations of the complex geometries. Our high-order MP scheme is applied to the calculations of the convective and surface tension terms. To obtain an effectively simultaneous solution of all equations, a novel dual-time stepping approach in conjunction with an implicit Runge–Kutta three-stage scheme is proposed. The reliability of the proposed numerical algorithm is then examined for a 1D Stefan condensation problem and two condensing flows including single bubble and steam-jet condensation problems. Particularly, for the single bubble condensation test, the bubble characteristics at different time instants are evaluated both qualitatively and quantitatively. For the steam-jet condensation test, the capability for capturing the evolution of interface deformations under different thermal and hydrodynamic flow conditions is highlighted. Finally, the effects of subcooling degree and steam mass flow rate on heat and mass transfer characteristics are investigated and discussed.

Development and Performance Evaluation of a Small Scale Municipal Solid Waste Incineration Plant

This study presents the design and testing of a waste-to-energy plant by incineration of small scale municipal solid waste to produce steam for electricity production. The average total waste generated within the study area was found to be 55,800kg/day, with an estimated calorific value of 13,958kJ/kg. The waste samples were collected, dried, shredded and weighed in order to reduce the moisture content to the acceptable minimum and decreases the surface area of the sample that will allow easier penetration of heat. The incinerator was designed using CATIA-5 software. The key performance indices of the developed plant are maximum furnace temperature, residence time, mass flow rate, steam pressures and amount of steam generated keeping the mass of waste constant per test but varying the air flow. The moving grate is inclined at an angle of 12° while the volume of the incineration combustion chamber was calculated to be 0.267m3. 150kg of small scale waste was fed into the combustion chamber of the incinerator to produce heat in order to fire the boiler filled to 70 litre capacity level. Tests were carried out with natural air flow and forced air supplied through the primary air nozzles at an air velocity of 6.2m/s. The obtained temperature/pressure results were: 464°C/5 bar and 528°C/7 bar and 542°C/7 bar for tests 1, 2 and 3 respectively. The steam produced in the boiler was able to run a steam turbine used to generate electricity. Preliminary results showed that such a plant could be used to complement the power supplied to the University as a set of 36 - 12V DC bulbs were powered for 15 minutes.

An Experimental Investigation of The Dynamic Effects in Upper Drum Boiler Under Steam Mass Flow Rate Variation

The dynamic effects in the “upper“ drum of the boiler (mechanical’s effects) are very complex problems and critical due to the pressure disturbance in the upper drum of the boiler. This work deals with an experimental investigation of the dynamic behavior of the boiler drum level system is reported from plant data (Al-Quds power plant) in Baghdad / Iraq under a particular condition of operating, and the mathematical equations of the boiler model variables explained and defined. The dynamic effects are investigated with increasing steam mass flow rate (10% and 20%) at the outlet of the boiler. The results showed that the rapid rise in the rate of steam mass flow causes the dynamic effects to increase (shrink and swell) by 15%, rates of evaporation and thus causes an increase in the volume of water inside the upper drum boiler that causes overheating in the tubes.

Dynamic simulation of a gas turbine for heat recovery at varying load and environment conditions

A novel solution of three-stage waste heat recovery from a gas turbine (11.35 MW) is proposed and its dynamic response characteristics with a series of load and environment change in the process of gas turbine operation is studied according to actual process requirements on an offshore platform. Integrating three processes under different temperature ranges is performed by using the flue gas to heat oil, generate steam and heat rejection water in turn with three heat exchangers (HE I, HE II and HE III), respectively. The dynamic simulation results show that the steam flow rate in HE II has obvious fluctuations as gas turbine load drops. Within the 10%, 20%, and 30% load decrease of gas turbine, the stabilized values of steam mass flow rate decrease by 7.6%, 16.3%, and 26.5%, respectively. The greater varying rate of the gas turbine load can accelerate the response speed but deteriorates system stability. The environment temperature change from 5 °C to 25 °C essentially affects the flue gas temperature from 473.18 °C to 496.70 °C, and it influences the system response linearly to a certain extent for the non-linear system expect for HE II. Since the phase transition process exists in HE II and the gas residence time is much shorter than liquid, the response speed and trend is different from the process in HE I and HE III.

English

This paper presents the effect of feed composition, xF, and feed thermal conditions on benzene-toluene distillation plant performance. An interactive computer model was developed to simulate the process using vapor-liquid equilibrium (VLE) data, mass and energy balances and McCabe-Thiele method. The feed thermal conditions studied were vaporized feed (VF), feed at its boiling point (FBP) and subcooled liquid (SCL) feed. The feed composition was varied between 0.20 and 0.45 kmol/kmol. The process was simulated at fixed feed flow rate (1000 kmol/h), reflux ratio (R = 4.0) and distillate and bottoms compositions (95 and 5%, respectively). The minimum reflux ratio, theoretical and actual number of stages, reboiler duty and steam mass flow rate, and boil-up ratio changed with increasing xF according to fourth-order polynomial functions. The condenser duty and cooling water flow rate increased linearly with xF. The effect of increasing xF on the stripping section operating line (SOL) is reported separately for different feed thermal conditions. While all q-lines for VF passed at (xB, xD) with decreasing slope; the q-lines for FBP were vertical and those for SCL feed were parallel. Graphical presentations of q-lines and SOLs for increasing xF were developed in this study. Key words: Distillation plant performance, feed composition, feed thermal conditions, number of stages, reboiler duty, condenser duty, boil-up ratio, mass and energy balances, vapor liquid equilibrium.

An improved model to evaluate the performance of solar-aided power generation plants

ABSTRACT Solar aided power generation (SAPG) is an efficient method to utilize solar thermal energy to generate power in association with traditional fossil-fueled power plants. In an SAPG plant, solar energy is used to replace extracted steam to preheat feedwater into the boiler in a regenerative Rankine power cycle. In previous SAPG plants’ performance evaluation models, a key assumption made is that the parameters at the outlets of the boiler, such as temperature and pressure, remain unchanged even if the steam mass flow rates through the boiler have changed due to the introduction of solar heat. This assumption actually makes the boiler to be modeled as a black box to simplify the model, but inevitably compromised the accuracy of the evaluation results. The error is sometimes so significant that some research conclusions are affected especially when the solar heat is used to replace the extraction steam before the reheating process. An improved SAPG evaluation model with the assumption that the boiler is modeled as a heat exchanger instead of a black box is proposed in this paper. The improved model accuracy has been demonstrated focusing on three SAPG power plants, namely 210 MW, 300 MW and 600 MW power plant. The errors are respectively reduced by 0.48%, 2.86% and 0.76% at 50% load. Moreover, three cases studies have been discussed focusing on the three SAPG power plants. The solar-power efficiency of replacing the second extraction steam is lower than that of replacing the third extraction steam after the error of boiler “black box” model is considered. The results indicate that using solar energy to replace higher stage of extraction steam is not necessarily better than replacing lower stage extraction steam as previously understood. The research provides a new insight into the role of solar replacement for different extracted steam levels in an SAPG power plant.

Equivalence analysis of simulation data and operation data of nuclear power plant based on machine learning

As an effective data pattern extraction method, machine learning is widely used in the field of nuclear power industry control, and has a great application. In order to solve the problem that there is a serious lack of operation data set for analyzing various variable conditions or accident conditions, this paper uses the maximum likelihood estimation and the least square estimation to prove that, when the simulation data of nuclear power plant and the operation data with different noise terms are used as the training data samples to train the machine learning algorithm models respectively, the difference between the two algorithms at each moment is only related to the mean of noise distribution. Especially when the mean of noise distribution is 0, they are equivalent. The conclusion shows that when the machine learning algorithm model is trained, the simulation data can supplement the operation data set. When the algorithm models are trained with the supplementary data set, the supplementary data will not change the calculations of the original algorithm model. Therefore, the simulation data can be used to expand the operation data set of variable conditions or accident conditions to improve the calculation accuracy of the algorithm models. In order to verify the conclusion, this paper uses simulation data and operation data with different noise terms to train the neural network algorithm models with L2 regularization term, and uses the algorithm models to calculate the steam mass flow rate at the outlet of main steam pipe of steam generator and the water temperature at the bottom of pressurizer. It is further proved that the calculations of thermal hydraulic transient operation parameters of the algorithm models trained by the operation data set with different noise terms are only equivalent to the translation of the calculations of the algorithm models trained by the simulation data set. And the value of translation is the mean of the noise distribution, which proves that the conclusion is effective.

Utilization of Crystalline and Amorphous Silica as a Sintering Inhibitor in Iron/Iron Oxide Thermochemical Water Splitting Cycle

Hydrogen as a chemical fuel and energy carrier can provide the path to solar energy storage to overcome the intermittency issues. Hydrogen can be produced by various methods; among them is the thermochemical water splitting of metal/metal oxide reduction oxidization (redox) reactions. Many redox cycles were identified, including the non-volatile redox pair, such as the iron/iron oxide. This redox pair has the capability to produce Hydrogen with rapid reaction rates especially when it is used in powder form due to the high specific reactive surface area. Yet, this pair suffers from sintering at temperatures exceeding 500°C. Sintering adversely affects the Hydrogen production process and inhibits the recycling of the powder. To overcome sintering, experimental investigations using elemental iron and silica were conducted as detailed in this paper. The oxidation of elemental iron (Fe) powder by steam to produce Hydrogen was carried out using a fluidized bed reactor. The investigations aimed at developing a practical sintering inhibition technique that can allow repeated redox cycles, stabilize the powder reactivity, and maintain Hydrogen production. The experimental investigations involved varying the fluidized bed temperature between 630–968°C. The steam mass flow rate was set to 2 g/min. To inhibit sintering, solid-state mixing of crystalline, or amorphous silica with porous iron powder was used at various iron/silica volume fractions. The investigations showed that mixing iron with silica hinders the sintering but reduces the Hydrogen yield. Mixing iron with crystalline silica with 0.5, 0.67, and 0.75 apparent volume fraction reduces the Hydrogen yield compared to pure iron by 20, 30, and 45%, respectively. Mixing iron with amorphous silica reduces the Hydrogen yield by 35 and 45%, as compared to pure iron, for iron 0–250 and 125–355 µm particle size distribution, respectively. The Hydrogen production rate for iron/amorphous silica mixtures surpassed that of the iron/crystalline silica. Mixing iron with amorphous silica prevented sintering at elevated bed temperatures in the range of 850°C, and only clumping occurred. The clumped samples restored their original powder condition with minimum agitation. Thus, solid-state mixing of amorphous silica with iron powder can be a promising technique to retard iron/iron oxide particles sintering.

Large scale experimental facility for performance assessment of the vacuum vessel pressure suppression system of ITER

The nuclear fusion reactor ITER (International Thermonuclear Experimental Reactor) foresees a Pressure Suppression System (PSS) in order to manage a Loss of Coolant Accident (LOCA) in the Vacuum Vessel (VV). A LOCA scenario is postulated to occur in the cooling systems of plasma facing components. The Vacuum Vessel Pressure Suppression System (VVPSS) has a key safety function because a large internal pressure in the VV could lead to a breach of the primary confinement barrier.Steam condensation would occur in ITER at sub-atmospheric pressure, differently than the applications in nuclear fission reactors. Steam direct contact condensation (DCC) in sub-atmospheric conditions have never been implemented before, therefore an experimental assessment of the VVPSS is necessary to simulate this phenomenon in ITER's thermal-hydraulic conditions.Under the financial support of ITER Organization, an experimental program was performed at the Department of Civil and Industrial Engineering (DICI) of the University of Pisa in the past 3 years, using a small-scale experimental rig (1/22 scale factor).In order to assess the scale laws elaborated by means of the experimental results obtained in this small scale facility, a Large Scale facility was built at University of Pisa. This facility is almost a full scale mock-up of ITER's VVPSS from the geometric point of view (1/1.09 scale factor) and it is 1/10 scale factor from the steam mass flow rate point of view.This paper illustrates the results of the first test campaign. A 1/10 scale sparger system SPS-A (having a diameter equal to DN125 and 100 holes) was used with a maximum steam mass flow rate of 0.5 kg/s. This experimental configuration represents real operating conditions on the basis of the results of elaborated similitude analysis. The preliminary analysis of the experimental results confirms the agreement in terms of condensation regimes between the two reduced scale (1/22 and 1/10 scale) as foreseen by the elaborated scale laws.

Design and Development of a Mini Steam Turbine for Domestic Electric-Powered Application

This work focuses on the design and development of a single stage De Laval impulse type of steam turbine connected to an AC generator for the purpose of generating electricity for domestic use. The system possesses several components such as turbine runner and blades, turbine casing, steam inlet nozzle and AC generator. The system is designed to work with a steam generator (boiler) fired by biogas, which is connected to the rotary (turbine blade) system via a nozzle. Factors such as steam pressure, temperature, velocity and mass flow rate of steam and nozzle angle are the key input variables that help in the development, construction and fabrication of the turbine wheel (blades and rotor). The developed mini steam turbine was simulated using solid works software and the von mises result obtained for maximum and minimum stresses of the turbine frame and stand unit were 2.725 × 105N/m2 and 4.447 × 101N/m2, respectively with yield strength of 2.5 × 108N/m2. Also, the von mises maximum and minimum stresses of the turbine blade were 3.522 × 107N/m2 and 7.064 × 104N/m2, respectively with a yield strength of 2.413 × 108N/m2. The developed mini-turbine is designed to withstand the working conditions based on the static simulation and analysis of results obtained.

Direct steam condensation at sub-atmospheric pressure: experimental tests and similitude analysis

This paper deals with experimental and theoretical analyses of the steam direct condensation at sub-atmospheric pressure. These operation conditions occur in the Vacuum Vessel Pressure Suppression System (VVPSS) of ITER Nuclear Fusion Reactor. This safety system permits to manage the Ingress of Coolant Event (ICE cat. IV) accident condition, postulated to occur in the ITER Vacuum Vessel (VV) as a consequence of the rupture of the shielding blanket cooling piping or the rupture of the divertor cassette piping.Experimental tests of steam direct condensation at sub-atmospheric pressures in a 1:22 scale facility were performed at the laboratory Guerrini of DICI-University of Pisa. Presently a full-scale facility is being building at DICI. This paper illustrates the similitude analysis elaborated to scale up the experimental results obtained in the reduced scale facility. The main variables which influence the steam direct condensation were analyzed and the relative scale laws determined. CFD numerical simulations of direct steam condensation in the actual geometry and in a vessel of equal volume permitted to verify some of the assumptions on which the scale laws are based. Scaling studies were first performed in order to calculate the transient of steam mass flow rate occurring during the ICE IV event in the scale apparatus, starting from the thermal hydraulic studies performed at ITER and successfully compared with the experimental results carried out in scaled apparatus. This confirmed the suitability of scale laws and in the same time the capability of the VVPSS to condense the injected steam at sub-atmospheric pressure, matching the safety goal to reduce the system pressurization.

INVESTIGATION OF EVAPORATION AND CONDENSATION PROCESS OF INDUCED FLOW USING STEAM EJECTOR

The research aims to understand the design parameters of steam ejector nozzle on the performance of flash evaporation induced by the effect of a steam jet passing through it. The research concentrates on studying the effect of ejector nozzle outlet diameter on induced flow from preheated water in a specified evaporator using a subsonic ejector. The thermal energy extracted from the condensed steam mixture in the condenser is used to heat the water in the evaporator. The experimental tests investigate the effect of nozzle geometry on the induced evaporation process by changing nozzle outlet diameter while keeping the pressure of evaporator, condenser and primary steam constant. The experimental results proved that both primary and secondary steam mass flow rates increase versus nozzle outlet diameter, while the entrainment ratio of secondary to primary steam flow rates decreases due to the restricted increase of the secondary steam mass flow rate. The mathematical model prepared to simulate the behaviour of the subsonic ejector is validated using the comparison between experimental and theoretical results. The mathematical model showed that maximum entrainment of 0.57 is obtained at a primary steam pressure of 2 bars when the nozzle outlet diameter is fixed at 1.5 mm, while minimum entrainment ratio of 0.17 is estimated at 1.5 bar pressure related to primary steam when the nozzle outlet diameter is fixed at 2.5mm. The authors recommend defining nozzle geometrical parameters according to the operating conditions of the experimental test rig to enhance ejector efficiency.

Energy, Exergy, Environmental (3E) and Parametric Assessment of a Triple-Pressure Reheat Combined-Cycle Power Plant

Abstract In this study, energy, exergy, and environmental (3E) assessments have been conducted on a proposed combined-cycle power plant (CCPP) with three pressure levels of the HRSG and reheating process. 3E design approaches cross-link mechano-electric and environmental objectives. Herewith, the suggested combined-cycle is formed by a gas unit, condenser, steam turbines, triple-pressure heat recovery steam generator (HRSG) and also utilizes reheat facilities and auxiliary components. It is observed that more than 56% of total exergy destruction occurs in the combustor, followed by HRSG (15.29%), steam turbines (roughly 15.02%), gas turbine (8.93%), air compressor (1.79%), and condenser (0.66%). A parametric study is also presented that examines the sensitivity of performance indicators to various environmental states, steam pressures, pinch points, and steam mass flow rates. Moreover, it is presented that the implementation of Siemens SGT-100-1S over other GT configurations can considerably reduce deficiency of the overall cycle. The effects of each contaminant mass flowrate (NOx, CO, UHC, and CO2) and adiabatic flame temperature (AFT) are also studied when the gas unit operates under partial power and incomplete combustion conditions. In conclusion, a number of potential causes of irreversibilities and corrective optimization guidance are offered for each main equipment of the CCPP.

Application of machine learning to develop a real-time air-cooled condenser monitoring platform using thermofluid simulation data

A data-driven surrogate model is proposed for a 64-cell air-cooled condenser system at a power plant. The surrogate model was developed using thermofluid simulation data from an existing detailed 1-D thermofluid network simulation model. The thermofluid network model requires a minimum of 20 min to solve for a single set of inputs. With operating conditions fluctuating constantly, performance predictions are required in shorter intervals, leading to the development of a surrogate model. Simulation data covered three operating scopes across a range of ambient air temperatures, inlet steam mass flow rates, number of operating cells, and wind speeds. The surrogate model uses multi-layer perceptron deep neural networks in the form of a binary classifier network to avoid extrapolation from the simulation dataset, and a regression network to provide performance predictions, including the steady-state backpressure, heat rejections, air mass flowrates, and fan motor powers on a system level. The integrated surrogate model had an average relative error of 0.3% on the test set, while the binary classifier had a 99.85% classification accuracy, indicating sufficient generalisation. The surrogate model was validated using site-data covering 10 days of operation for the case-study ACC system, providing backpressure predictions for all 1967 input samples within a few seconds of compute time. Approximately 93.5% of backpressure predictions were within ±6% of the recorded backpressures, indicating sufficient accuracy of the surrogate model with a significant decrease in compute time.