Outlet Steam Research Articles

CFD analysis for optimizing superheater components for high temperature steam production for use in an SOEC

ABSTRACT A solid oxide electrolyzer cell (SOEC) can reversibly generate hydrogen by electrolyzing superheated steam or produce electricity from a fuel cell by using hydrogen. Converting water into steam by using the waste heat from other processes can improve the efficiency of high-temperature electrolysis for directly converting steam. In the present study, steam at over 180°C and 3.4 bars generated from a boiler is converted into superheated steam at over 700°C and 3 bars by using a cylindrical steam superheater and the waste heat of flue gas at 900°C from a solid refuse fuel combustor. However, during the production of steam at 700°C and its transportation to the SOEC, a conventional superheater cannot produce a temperature of 700°C owing to poor heat transfer and energy loss. To determine the optimal conditions for generating steam at 700°C or above, we evaluate the effect of varying different superheater components, such as the shape of the top part of the superheater, number of steam inlet pipes, length, and coil rotation diameter of coil injection pipes, and steam inlet and outlet pipe diameters, through computational fluid dynamics analyses. Under the optimal conditions, the superheater with two steam injection pipes is the most effective, producing a maximum outlet steam temperature of ~753°C.

An Integrated IoT LabVIEW Based Fuzzy-PLC Controller for Automation of Boiler

The proposed prototype, to develop and automate and controlling of steam outlet from the boiler unit in the Power Plants using Fuzzy logic-based PLC Controller. The set point of the steam outlet could be decided by the Fuzzy Logic Controller. Automation is a growing technology in almost all fields and It reduces the man power and time complexity in all the way to the thermal power plant also. It reduces the risk of making mistakes and avoid any danger. The details of the load is collected from P.T and then given to the LabVIEW. The data about the load requirements, peak load data requirements ae once fed into the LabVIEW. The LabVIEW sends signals to the PLC and steam outlet is controlled by Servo Motor. The steam outlet set point is measured and controlled by fuzzy logic with the help to PLC controller. Based on alternator current and voltage signal the fuzzy logic will decide the steam outlet set point. If in case the load requirement is higher or lower, the changes in the coal input and the water requirement are changed by means Fuzzy logic control. The steam valve sensor closes or opens the valve by servo motor using the variable frequency drive that is connected to the PLC. Depending upon the load, to the steam turbine. The PLC is connected to the ethernet by means in LabVIEW, in which the data are collected are given to the authorized person in the control room. If in case required the data can be used to store the data in the cloud for future use.

Creep rupture life assessment of superheater tube with oxide formation in power plant

AbstractThis paper proposes a method for predicting the creep rupture life of superheater tubes, considering the continuous increasing metal temperature and stress as a result of oxide formation. The steam‐side oxide growth was assessed by the parabolic oxidation rate law, and the temperature profiles of superheater tubes was calculated combining the 3D computational fluid dynamics simulation and the 1D analytical models. Based on the estimated temperature and maximum elastic hoop stress, the parametric extrapolation technique was utilized to assess the creep rupture life. The validity of this method was confirmed by measuring the oxide thickness and the steam temperature in the field. The results found that T91 alloy in the steam outlet region and T23 alloy at the connection point was susceptible to creep rupture failure, which had the greatest cumulative damage and thickest oxide scale. The cumulative damage of superheater tubes varied significantly with tube count. Results suggested that replacement of the particular T91 alloy tubing section having the minimum creep rupture life with a better heat‐resistant steel would avoid mechanical failure by creep for the subject boiler system.

Feasibility research on a hybrid solar tower system using steam and molten salt as heat transfer fluid

Feasibility research on a hybrid solar tower system using steam and molten salt as heat transfer fluid

Thermal-Hydraulic Calculation and Analysis on Evaporator System of a 1000 MW Ultra-Supercritical Pulverized Combustion Boiler with Double Reheat

A double reheat ultra-supercritical boiler is an important development direction for high-parameter and large-capacity coal-fired power plants due to its high thermal efficiency and environmental value. China has developed a 1000 MW double reheat ultra-supercritical boiler with steam parameters of 35 MPa at 605°C/613°C/613°C. Reasonable water wall design is one of the keys to safe and reliable operation of the boiler. In order to examine the thermal-hydraulic characteristics of the double reheat ultra-supercritical boiler, the water wall system was equivalent to a flow network comprising series-parallel circuits, linking circuits and pressure nodes, and a calculation model was built on account of the conservation equations of energy, momentum and mass. Through the iterative solving of nonlinear equations, the prediction parameters of the water wall at boiler maximum continue rate (BMCR), 75% turbine heat-acceptance rate (THA) and 30% THA loads, including total pressure drops, flow distribution, outlet steam temperatures, fluid and metal temperatures were gotten. The results of calculation exhibit excellent thermal-hydraulic characteristics and substantiate the feasibility of the water wall design of the double reheat ultra-supercritical boiler.

Influences of fabrication tolerance on thermal hydraulic performance of HTGR helical tube once through steam generator

Influences of fabrication tolerance on thermal hydraulic performance of HTGR helical tube once through steam generator

INFLUENCE OF THERMAL RESISTANCE OF AIR CONDENSER TUBES ON STEAM COOLING EFFICIENCY


 
 
 The research is carried out using a mathematical model of conditions and features of condensation processes with the influence of changes in internal and external thermal resistances of working bodies, which occur during contamination of outside and inside metal pipes of heat exchange surfaces of air condenser. capacitor. Particular attention is paid to the selection, detailing and determination of more than twenty basic parameters that characterize the operation of the direct cooling unit of the condensing unit for the summer, the conditions of heat transfer processes between the working bodies taking into account the finned outer surface of elliptical condenser tubes. The results of experiments on the mathematical model are analyzed and the influence of the incoming air velocity and ambient temperature on the output steam pressure in the condenser direct air cooling system within the change of internal and external thermal resistances in the range 0-0.001(m2·K)/W due to cooling tube contamination is determined. air condenser steam turbine installation. Conditions, character and features of influence of thermal resistance of pollution in cooling tubes on steam pressure at an exit from them are defined, the basic factors defining steam pressure at an exit, necessity of the organization of control of thermal resistance of pollution in a pipe during unit operation at variable operating conditions and expediency is substantiated. conducting test studies of operating modes while taking into account the influence of thermal resistance of external and internal pollution on the thermal efficiency of the cooling unit.
 
 
 
 Studies have shown that at a fixed value of the heat load of the exhaust steam, the pressure of the steam outlet increases with increasing ambient temperature and decreasing the speed of the incoming air.
 
 
 
 
 

CFD analysis of steam superheater operation in steady and transient state

CFD analysis of steam superheater operation in steady and transient state

Dynamic characteristics analysis of a once-through heat recovery steam generator

Dynamic characteristics analysis of a once-through heat recovery steam generator

Assessment of potential service-life performance for MarBN steel power plant header under flexible thermomechanical operations

This paper is concerned with the service-life assessment of 9Cr steels superheater outlet steam header subjected to realistic subcritical and future ultra-super critical flexible operating conditions. The proposed methodology is achieved via a combined program of high temperature strain-controlled fatigue tests, temperature- and time-dependent unified viscoplastic model for thermomechanical fatigue analysis, and Smith-Watson-Topper critical plane criterion for multi-axial life prediction. Samples of idealised operational transients with particular attention on the starting-up cycle is fully coupled with the computational modelling of header component for the high temperature performance assessment. The predicted results indicate that: (i) the header shell inner-bore saddles at weld regions are the critical locations that lead to earlier potential fatigue crack initiation, and (ii) the predicted lifetime under subcritical conditions correlates reasonably with the industrial experience. A steam header manufactured from MarBN operating under ultra-super critical condition is shown to have comparable life performance with the P91 header operating under subcritical condition.

Coupled simulation and validation of a utility-scale pulverized coal-fired boiler radiant final-stage superheater

Coupled simulation and validation of a utility-scale pulverized coal-fired boiler radiant final-stage superheater

Quantitative Feedback Theory design of valve position control for co-ordinated superheater control of main steam temperatures of power plant boilers

Quantitative Feedback Theory design of valve position control for co-ordinated superheater control of main steam temperatures of power plant boilers

A Comprehensive Thermal and Structural Transient Analysis of a Boiler’s Steam Outlet Header by Means of a Dedicated Algorithm and FEM Simulation

Increasing the share of renewables in energy markets influences the daily operation of thermal power units. High capacity power units are more frequently operated to balance power grids and, thus, steam boilers are exposed to unfavorable transient states. The aim of this work was to perform thermal and structural analyses of a boiler’s outlet steam header, with a capacity of 650∙103 kg/h (180 kg/s) of live steam. Based on the measured steam pressure and temperatures on the outer surface of the component, transient temperature fields were determined by means of an algorithm that allows determination of transient stress distributions on the internal and external surfaces, as well as at stress concentration regions. In parallel, a finite element method simulation was performed. A comparison of the obtained results to a finite element analysis showed satisfactory agreement. The analyses showed that the start-up time could be reduced because the total stress did not exceed the allowed values during the regular start-up of the analyzed power unit. The algorithm was efficient and easy to implement in the real control systems of the power units. The numerical approach employed in the presented algorithm also allowed for determination of the time- and place-dependent heating rate value, which can be used as input data for the control system of the power unit.

Research and Adjustment of Temperature Deviation on Heating Wall of Front and Rear Wall Opposed Coal-fired Boiler of 1000WM Unit

No.2 boiler is designed by Dongfang boiler group Co., LTD, and is ultra supercritical parameter boiler with variable pressure. In order to alleviate the side wall temperature deviation and to reduce the maximum wall temperature of super-heater, the total air volume alteration test, external secondary air damper alteration test, over-fire air alteration test and the shrinkage adjustment is performed. The test results show that oxygen increase and shrinkage adjustment can improve the deviation of wall temperature and steam temperature. After increasing oxygen, plate super-heater wall temperature deviation reduced by 26 °C, and its outlet steam temperature deviation reduced by 14 °C. After shrinkage adjustment, plate super-heater wall temperature deviation reduced by 34 °C, and the wall temperature difference of final super-heater reduced from 50 °C to 25 °C, the wall temperature of side B plate super-heater reduced by 25 °C.

Thermal analysis of HTGR helical tube once through steam generators using 1D and 2D methods

Thermal analysis of HTGR helical tube once through steam generators using 1D and 2D methods

Experimental and theoretical investigations of two-phase flow in low pressure steam–water injector

Experimental and theoretical investigations of two-phase flow in low pressure steam–water injector

CFD-simulation-based optimization of superheater for steam production from waste heat of SRF combustor

ABSTRACTA superheater uses waste heat from a combustor or an incinerator to produce superheated steam through heat exchange between saturated steam and exhaust (flue) gas. Superheaters predominantly use thin tube-type pipes, which makes it difficult to experimentally determine internal phenomena such as the flow, pressure distribution, and temperature distribution. Computational fluid dynamics (CFD) has recently been used to successfully analyze superheaters. In this study, steam at 180°C and 3.4 bars was converted via a cylindrical superheater into superheated steam above 700°C and 3bars using exhaust gas at 900°C from a solid refuse fuel combustor. The superheated steam was then supplied to a high-temperature solid oxide electrolyte cell to increase the hydrogen production efficiency of water electrolysis. CFD analyses were also conducted using a commercial Fluent simulator to study the effects of the furnace size, superheater size, inlet and outlet diameters, and steam generation amount on the exit temperature. The CFD simulation results were determined to be valid by a pilot experimental apparatus, which showed that the error rate between the experimental measurements and the simulation results was less than 2%. For the same volume, the superheater with the largest surface area (0.4-m diameter and 1-m length) produced the highest exit temperature. For steam inlet and outlet diameters of 8 mm, the highest exit temperature was 652°C. By reducing the flow rate to 70 kg/h, steam at over 700°C and 3 bars could be obtained under these optimal conditions.

Three-Dimensional Porous Solar-Driven Interfacial Evaporator for High-Efficiency Steam Generation under Low Solar Flux.

Solar steam generation is critical for many important solar-thermal applications, but is challenging to achieve under low solar flux due to the large evaporation enthalpy of water. Here, we demonstrate a three-dimensional porous solar-driven interfacial evaporator that can generate 100 °C steam under 1 sun illumination with a record high solar-to-steam conversion efficiency of 48%. The high steam generation efficiency is achieved by localizing solar-thermal heating at the evaporation surface and controlling the water supply onto the porous evaporator through tuning its surface wettability, which prevents overheating of the evaporator and thus minimizes conductive, convective, and radiative heat losses from the evaporator. The design of steam outlet located at the sidewall of the evaporator rather than from the solar absorber surface not only facilitates the collection of generated steam, but also avoids potential blockage of solar radiation by the condensing steam. The high-efficiency solar-driven evaporator has been used to generate hot steam for outdoor removal of paraffin on the wall of oil pipelines, offering a promising solution to mitigate the wax deposition issue in petroleum extraction processes.

Corrosion behaviour of Ni and nickel aluminide coatings exposed in a biomass fired power plant for two years

Corrosion behaviour of Ni and nickel aluminide coatings exposed in a biomass fired power plant for two years

Study the Effect of Diameter and Depth of Parabolic Dish Collector on the Concentration Ratio and Temperature Amount of Solar Tower Receiver

This work introduces three models of parabolic dish collectors with different dimension to study the effect of change diameter and depth of the dish on the position of focus point and concentration ratio and the temperature of outlet hot water or steam by using different receivers. The present work deals with a new system consists of dish and receiver to produce hot water and steam from solar energy. The parabolic dish solar collector fabricated from iron with different dimension the first model with diameter (82 cm) and depth (6 cm), this gives focus length (70cm) and Concentration ratio (25.6). The second model with a diameter (100cm) and depth (3 cm), this give focus length (208cm) and concentration ratio (15). The third model with a diameter (150cm) and depth (12cm), This give focus length (100cm) and concentration ratio (399) and the front side covered by nickel sheet metal to focus the solar radiation upon the receiver for all models . Three different shapes of receiver tanks used with the third model ; namely case one which used rectangular receiver tank (100×50×5) cm3 filled with 25 liter of water. Case two used helical copper coil (12.5 mm× 3 m) inside aluminum cylindrical vessel (0.2 m ×0.6 m). Case three used radiator heat exchanger receiver tank (37×47×4) cm3 filled with 3 liter of water. Use low cost and available materials to manufacture the experimental part. The dish, used as part of the solar reflector, covered by several strips of nickel sheet metal. When the parabolic dish collector was operational, the temperature of water was 60 oC in rectangular receiver tank, 75 0C within the copper coil and 125 oC in radiator device receiver. For rectangular receiver tank, hot water obtained within time (2 h), for copper coil receiver tank, hot water obtained within time (30 min) and for radiator heat exchanger receiver, steam obtained within time (20 min).