scholarly journals Analysis of Precooling Injection Transient of Steam Generator for High Temperature Gas Cooled Reactor

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Yan Wang ◽  
Lei Shi ◽  
Yanhua Zheng
Keyword(s):  
High Temperature ◽  
Mass Flow Rate ◽  
Steam Generator ◽  
Mass Flow ◽  
Flow Rate ◽  
System Analysis ◽  
Water Injection ◽  
Normal Operation ◽  
Coolant Temperature ◽  
High Temperature Gas

After a postulated design basis accident leads high temperature gas cooled reactor to emergency shutdown, steam generator still remains with high temperature level and needs to be cooled down by a precooling before reactor restarts with clearing of fault. For the large difference of coolant temperature between inlet and outlet of steam generator in normal operation, the temperature distribution on the components of steam generator is very complicated. Therefore, the temperature descending rate of the components in steam generator needs to be limited to avoid the potential damage during the precooling stage. In this paper, a pebble-bed high temperature gas cooled reactor is modeled by thermal-hydraulic system analysis code and several postulated precooling injection transients are simulated and compared to evaluate their effects, which will provide support for the precooling design. The analysis results show that enough precooling injection is necessary to satisfy the precooling requirements, and larger mass flow rate of precooling water injection will accelerate the precooling process. The temperature decrease of steam generator is related to the precooling injection scenarios, and the maximal mass flow rate of the precooling injection should be limited to avoid the excessively quick temperature change of the structures in steam generator.

Design, Operation and Maintenance of Thermal Hydraulic Instrumentation System of HTR-10

2010 ◽  
Author(s):  
Liqiang Wei ◽  
Shuoping Zhong
Keyword(s):  
High Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Steam Pressure ◽  
Coolant Temperature ◽  
Primary Loop ◽  
Operation And Maintenance ◽  
Main Steam ◽  
High Temperature Gas

The 10 MW high temperature gas-cooled reactor–test module (HTR-10) reached the first critical at the end of year 2000, and has been running for over 9 years safely and stably till now. Comparing with the Pressure Water Reactor (PWR), HTR-10 has many different characteristics, such as core construction, special fuel elements, helium coolant and so on. Thus the thermal hydraulic parameter measurement has special requirement and it is indispensable to select or develop some new class 1E instrumentation and devices. This paper describes measurement requirements, measurement method and measurement instrumentations for measuring coolant temperature, primary loop pressure, primary loop mass flow rate, primary loop humidity, main steam pressure, feedwater mass flow rate, in-core components temperature, pressure vessel surface temperature. The class 1E sheathed thermocouples and thermocouple penetration assembly, the class 1E orifice plate throttle device, and the data acquisition and supervision system that were developed by the Institute of Nuclear and New Energy Technology (INET) according to the criteria IEEE 323 and IEEE 344 are introduced in detail. HTR-10 has been operated successfully for over 9 years up to the present. The operation and maintenance experience of above-mentioned instrumentations shows they are safe and reliable at normal and abnormal conditions. The experience described in this paper is valuable for the latter 2 × 250 MW modular high temperature gas-cooled reactor.

scholarly journals Procedure of Active Residual Heat Removal after Emergency Shutdown of High-Temperature-Gas-Cooled Reactor

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Xingtuan Yang ◽  
Yanfei Sun ◽  
Huaiming Ju ◽  
Shengyao Jiang
Keyword(s):  
High Temperature ◽  
Heat Shock ◽  
Steam Generator ◽  
Flow Rate ◽  
Heat Removal ◽  
Emergency Shutdown ◽  
Start Up ◽  
Sudden Load ◽  
High Temperature Gas ◽  
Residual Heat

After emergency shutdown of high-temperature-gas-cooled reactor, the residual heat of the reactor core should be removed. As the natural circulation process spends too long period of time to be utilized, an active residual heat removal procedure is needed, which makes use of steam generator and start-up loop. During this procedure, the structure of steam generator may suffer cold/heat shock because of the sudden load of coolant or hot helium at the first few minutes. Transient analysis was carried out based on a one-dimensional mathematical model for steam generator and steam pipe of start-up loop to achieve safety and reliability. The results show that steam generator should be discharged and precooled; otherwise, boiling will arise and introduce a cold shock to the boiling tubes and tube sheet when coolant began to circulate prior to the helium. Additionally, in avoiding heat shock caused by the sudden load of helium, the helium circulation should be restricted to start with an extreme low flow rate; meanwhile, the coolant of steam generator (water) should have flow rate as large as possible. Finally, a four-step procedure with precooling process of steam generator was recommended; sensitive study for the main parameters was conducted.

A Novel Technique for Measuring Stagnation Quantities and Gas Composition in High Temperature Flows

2010 ◽  
Author(s):  
Michela Massini ◽  
Robert J. Miller ◽  
Howard P. Hodson ◽  
Nick Collings
Keyword(s):  
High Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Stagnation Pressure ◽  
Temperature Measurements ◽  
Stagnation Temperature ◽  
Gas Composition ◽  
Reference Measurements

A new probe has been developed to measure the time averaged stagnation temperature, stagnation pressure and gas composition. This probe can be used in the high temperature regions of gas turbines, including downstream of the combustor and in the first stages of the high pressure turbines, as well as in other environments. The principal benefits of the new probe are that it overcomes the limitations of the standard methods that are used to measure temperature in high temperature environments and that it replaces three separate probes, for the three quantities mentioned above, with one single probe. A novel method of measuring temperature is used, which improves upon the accuracy of thermocouples and increases the temperature operating range. The probe consists of a choked nozzle placed in the hot flow at the point of interest. The working principle is based on the theory that for a choked nozzle, there is a fixed relationship between the stagnation quantities, the gas characteristics and the mass flow rate through the nozzle. The probe has an aspirated phase, where the gas composition and the mass flow rate are measured and a stagnated phase, where the stagnation pressure is measured. The stagnation temperature is determined from the above quantities. The operating principle has been proven valid through laboratory and rig tests. The probe has been successfully tested in a Rolls-Royce Viper engine up to 1000K and 2 bar and in a combustor rig up to 1800K and 4 bars. Measurements of stagnation temperature, stagnation pressure and gas compositions for these tests are presented in the paper and are compared with reference measurements. The accuracy of stagnation pressure and gas composition measurements is equal to the accuracy achievable with techniques that are commonly used in gas turbines. The estimated achievable accuracy of the aspirated probe in terms of temperature measurements is ±0.6%, i.e. ±10K at 1800K, which improves upon the accuracy of temperature measurements performed with standard thermocouples at the same temperatures, the uncertainty of which could be as high as ±2%.

scholarly journals Estimation of condensate mass flow rate during purging time in heat recovery steam generator of combined cycle power plant

2014 ◽  
Vol 18 (4) ◽  
pp. 1389-1397 ◽  
Author(s):  
M.A. Ehyaei
Keyword(s):  
Mass Flow Rate ◽  
Steam Generator ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Recovery ◽  
Steam Pressure ◽  
Combined Cycle ◽  
Heat Recovery Steam Generator ◽  
Gas Temperature ◽  
Condensate Formation

In this paper the transient modeling of HRSG (Heat recovery steam generator) in purging time was considered. In purging time, compressed air from the gas turbine was used to purge a combustible gas from HRSG. During this time; steam condensate was formed in the superheater stage which should be drained completely to avoid some problems such as deformation of superheaters. Because of this reason, estimation of drain formation is essential to avoid this problem. In this paper an energy model was provided and this model was solved by MATLsoftware. Average model error is about 5%. Results show that, during purge time, steam temperature was decreased from 502 (?C) (Superheater 2), 392 (?C) (Superheater1) and 266 (?C) (Evaporators 1&2) to 130 (?C), 130 (?C) and 220 (?C), respectively and also steam pressure was decreased from 52 (bar) to 23(bar) during purge time. At end of purge time, condensate formation was about 220 (l) when inlet gas temperature was equal to 100 (?C) and purge gas mass flow rate was equal to 386.86 (kg/s).

scholarly journals Thermal performance measurement of additive manufactured high-temperature compact heat exchangers

2021 ◽  
Vol 2116 (1) ◽  
pp. 012095
Author(s):  
M. Fuchs ◽  
D. Heinrich ◽  
X. Luo ◽  
S. Kabelac
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Fluid Temperature ◽  
Test Rig ◽  
Temperature Heat

Abstract Due to increased distribution of high-temperature processes in energy and process plants, more efficient and compact high-temperature heat exchangers are being developed. The additive manufacturing allows the construction of compact sizes and application-specific requirements. To evaluate the thermal performance of these heat exchangers, experimental investigations are evident. This study presents a test rig for testing compact high-temperature heat exchangers as well as a first set of thermal performance data of an additively manufactured plate-fin heat exchanger. The test rig can provide a maximum fluid temperature of 900°C and a maximum mass flow rate of 0.8 kg/min. A steam unit can add steam to the fluid stream to evaluate the influence of gas radiation on the thermal performance. The capabilities of this test rig are being tested with the plate-fin heat exchanger, varying the mass flow rate between 0.2 - 0.52 kg/min at a hot and cold inlet temperature of 750°C and 250°C. The overall effectiveness of the heat exchanger is approx. 0.9.

Radiation and Convection Heat Flux Sensor for High Temperature Gas Environment

1998 ◽  
Author(s):  
Nelson Martins ◽  
Maria da Graça Carvalho ◽  
Naim Afgan ◽  
Alexander Ivanovich Leontiev
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Critical Mass ◽  
Flux Measurement ◽  
Heat Fluxes ◽  
Sensing Element ◽  
Porous Element

The heat flux measurement is one of the essential parameter for the diagnostic of thermal systems. In the high temperature environment there are difficulties in differentiating between the convective and radiation component of heat flux on the heat transfer surface. A new method for heat flux measurement is being developed using a porous sensing element. The gas stream flowing through the porous element is used to measure the heat received by the sensor surface exposed to the hot gas environment and to control whether or not the sensing element receives the convection component of the total heat flux. It is possible to define a critical mass flow rate corresponding to the destruction of the boundary layer over the sensing element. With subcritical mass flow rate the porous sensing element will receive both the convective and radiative heat fluxes. A supercritical mass flow rate will eliminate the convective component of the total heat flux. Two consecutive measurements considering respectively a critical and a sub-critical mass flow rate can be used to determine separately the convection and radiation heat fluxes. A numerical model of sensor with appropriate boundary condition has been developed in order to perform analysis of possible options in the design of the sensor. The analysis includes: geometry of element, physical parameters of gas and solid and gas flow rate through the porous element. For the optimal selection of the relevant parameters an experimental set-up was designed, including the sensor element with corresponding cooling and monitoring system and high temperature radiation source. Applying the respective measuring procedure the calibration curve of the sensor was obtained. The linear dependency of the heat flux and respective temperature difference of the gas was verified. The accuracy analysis of the sensor reading has proved high linearity of the calibration curve and accuracy of ± 5%.

scholarly journals DESIGN ANALYSIS ON OPERATING PARAMETER OF OUTLET TEMPERATURE AND VOID FRACTION IN RDE STEAM GENERATOR

2017 ◽  
Vol 19 (1) ◽  
pp. 33 ◽  
Author(s):  
Sukmanto Dibyo ◽  
Ign. Djoko Irianto
Keyword(s):  
Mass Flow Rate ◽  
Void Fraction ◽  
Steam Generator ◽  
Mass Flow ◽  
Flow Rate ◽  
Superheated Steam ◽  
Operating Parameter ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Helium Gas

HTGR is one of the next generation reactor types. HTGR is currently considered as one of the leading reactors for the future nuclear power plant. The steam generator is one of the main components in HTGR as well as in RDE.  In the steam generator, the heat is transferred by high temperature helium gas in the shell side to water in the tube side to generate the superheated steam. the purpose of this work is to design the operating parameter of outlet temperature and void fraction of steam based on feed water mass flow rate and inlet temperature variations in RDE steam generator. In this work, the Chemcad program was used. Both inlet and outlet temperature of helium gas have been set up as boundary conditions. The result shows that using the mass flow rate of 4.3 kg/s - 4.8 kg/s and water inlet temperature of 110 oC - 160 oC, the superheated steam outlet temperature (void fraction = 1.0) is obtained in the range of 275.5 oC – 600 oC.This analysis is beneficial to assess 10 MW RDE design especially in the steam generator system operating parameters.Keywords: outlet temperature, void fraction, superheated steam, RDE steam generator ANALISIS DESAIN PARAMETER OPERASI UNTUK TEMPERATUR KELUARAN DAN FRAKSI UAP PADA PEMBANGKIT UAP RDE. Reaktor daya HTGR adalah salah satu tipe reaktor generasi lanjut. HTGR saat ini merupakan desain reaktor yang dipertimbangkan untuk pembangkit listrik unggulan dimasa mendatang. Pembangkit uap merupakan salah satu komponen utama pada HTGR begitu pula pada RDE. Di dalam pembangkit uap, panas dari gas helium temperatur tinggi pada sisi shell di transfer ke air pada sisi tube pembangkit uap untuk menghasilkan uap lewat jenuh. Tujuan analisis ini adalah mendesain parameter operasi terhadap temperatur keluaran dan fraksi uap berdasarkan variasi laju alir massa air umpan dan temperatur masuk pada RDE. Dalam analisis digunakan program Chemcad, temperatur gas helium masuk dan keluar ditentukan sebagai kondisi batas. Hasil menunjukkan bahwa dengan menggunakan laju alir massa 4,3 kg/detik - 4,8 kg/detik dan temperatur masukan air umpan dari 110 oC -160 oC dapat diperoleh uap lewat jenuh (fraksi uap= 1,0) pada temperatur keluaran dalam rentang 275,5 oC - 600 oC. Analisis ini berguna untuk memberikan kajian desain RDE 10 MW khususnya parameter operasi sistem pembangkit uap.Kata-kata kunci: temperatur keluaran, fraksi uap, uap lewat jenuh, pembangkit uap RDE 

Study on Pressure Relief Transient for High Temperature Gas Cooled Reactor

2012 ◽  
Author(s):  
Yan Wang
Keyword(s):  
High Temperature ◽  
Steam Generator ◽  
System Analysis ◽  
Cold Shock ◽  
Cooling System ◽  
Cooling Water ◽  
Pressure Relief Valve ◽  
Relief Valve ◽  
Pressure Relief ◽  
High Temperature Gas

After a supposed accident lead the reactor to shutdown, the residual heat generated from the decay will be removed out by the cooling system. A cooling water flow will be pumped into the steam generator for cooling the reactor after the pressure of the secondary side of the steam generator is decreased to a lower design value with opening of the pressure relief valve which is installed on the live-steam pipeline. But the temperature of the heat-exchange tubes and the tube plate at the outlet of the steam generator whose temperature in the steady-state operation is 570° high, need to be cooled down to about 200° for the material limitation before the cooling water is injected, to avoid the cold-shock damage on the components. In this paper, exampled as the 200MWe high temperature gas cooled reactor (HTR-PM), a general thermal-hydraulic system analysis code is used for modeling and simulating numerically the pressure relief transient after the accident. The results show the structure components of the steam generator will be cooled down effectively to mitigate the cold-shock damage from the cooling water during the transient with the designed pressure value of 1MPa where the pressure relief valve in 30mm diameter will be closed. It provides supports for the evaluation on the feasibility of cooling water injection and also for the material stress analysis on some relevant components in the steam generator design.

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