Experimental research on space distribution of reverse flow U-tubes in steam generator primary side

2022 ◽  
Vol 388 ◽  
pp. 111650
Author(s):  
Jianli Hao ◽  
Mingrui Li ◽  
Wenzhen Chen ◽  
Lei Yu ◽  
Lei Ye
Keyword(s):  
Steam Generator ◽  
Experimental Research ◽  
Reverse Flow ◽  
Space Distribution

scholarly journals Effect of Heaving Movement on Flow Instability in U-Tubes of Marine Steam Generator under Natural Circulation

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Jianli Hao ◽  
Wenzhen Chen ◽  
De Zhang
Keyword(s):  
Steam Generator ◽  
Single Phase ◽  
Flow Instability ◽  
Reverse Flow ◽  
Natural Circulation ◽  
Critical Mass ◽  
Space Distribution ◽  
Tube Length ◽  
One Dimensional ◽  
Acceleration Amplitude

Under heaving movement conditions, the single phase flow instability in U-tubes is affected by the additional force, which will influence the marine reactor operation. In the present work, one-dimensional thermal-hydraulic model in U-tubes under heaving movement conditions is established, and the critical pressure drop (CPD) and critical mass flow rate (CMFR) which relate to the occurrence of reverse flow in U-tubes are proposed and analyzed. The effects of the heaving period and heaving acceleration amplitude on the flow instability in U-tubes with the different length are discussed. It is shown that (1) the CPD and CMFR are obviously affected by the heaving movement, which means that the reverse flow characteristic in U-tubes will be changed; (2) the fluctuation periods of the CPD and CMFR are the same as the heaving period, but the fluctuation magnitude of them is little affected by the heaving period; (3) the relative changes of CPD and CMFR are the linear function of heaving acceleration amplitude; and (4) the U-tube length has little influence on the relative changes of CPD and CMFR compared with the heaving acceleration amplitude, which means that the heaving movement has little influence on the space distribution of reverse flow in the U-tubes of marine steam generator.

Flow Reversal in a Horizontal Type Natural Circulation Heat Recovery Steam Generator

2006 ◽  
Author(s):  
Heimo Walter ◽  
Wladimir Linzer
Keyword(s):  
Steam Generator ◽  
Heat Recovery ◽  
Reverse Flow ◽  
Natural Circulation ◽  
Heating Surface ◽  
Heat Absorption ◽  
System Pressure ◽  
Horizontal Type ◽  
The Stability ◽  
The Individual

Natural circulation heat recovery steam generators (HRSG) are used in many applications for the thermal recycling of the waste flue gas. Many of these boilers are designed as a horizontal type HRSG (see fig. 1). The evaporator of such a steam generator is characterized by an array of parallel tubes with different heat input. The paper presents the results of a theoretical stability analysis for a HRSG with a vertical tube bank. For the horizontal type HRSG the static instability, namely the reverse flow was analysed. The study was done at low system pressures and under hot start-up conditions for the boiler. The investigations show the influence of the geometry, the system pressure and the heat absorption of the individual tubes in the evaporator on the stability of the boiler. The aim of the study was to find design criteria to avoid reverse flow in the tubes of the evaporator. Addition of flow resistance at certain locations of the evaporator can improve the stability. A higher stability will be also achieved by the homogenization of the heat absorption in the individual layers of the bundle heating surface.

The Impact of RELAP5 Pipe Break Flow Rates Associated With Reverse Flow Limiter Removal for Steam Generator Replacement

2006 ◽  
Author(s):  
Dong Zheng ◽  
Julie M. Jarvis ◽  
Allen T. Vieira
Keyword(s):  
Steam Generator ◽  
Reverse Flow ◽  
The United States ◽  
Operating Conditions ◽  
Hazard Evaluation ◽  
Flow Rates ◽  
Choked Flow ◽  
Pipe Break ◽  
The Impact ◽  
Generator Replacement

Pipe break flow rates are calculated for a main feedwater line break (FWLB) in the main steam valve vault (MSVV) for a PWR Steam Generator Replacement (SGR). A reverse flow limiter is installed in the original steam generator (OSG) feedwater nozzle to limit the blowdown flowrate in the event of a postulated FWLB. This feature is not incorporated in the replacement steam generator (RSG) design. The change in RSG nozzle design in conjunction with new operating conditions results in increased FWLB mass and energy releases which can impact environmental temperatures and pressures and flooding levels. In the United States, benchmarking for safety related analyses is necessary in consideration of 10CFR50.59 requirements. RELAP5/MOD3 is used to model the pipe break flowrates for a FWLB at different break locations. The benchmark FWLB blowdown releases are larger than the OSG design basis blowdown releases due to differences in RELAP5/MOD3 versions which are found to have different algorithms for subcooled choked flow. The SGR FWLB blowdown release rates are determined to have minimal impact on the compartment temperature and pressure response. However, the flooding levels and associated equipment qualification are potentially impacted. Modeling techniques used to minimize the impact of the SGR blowdown releases on MSVV flooding levels include modeling flashing effects, more realistic RSG temperature distribution, inventory depletion and Auxiliary Feedwater (AFW) flow initiation time, and considering loss of offsite power scenarios. A detailed flooding hazard evaluation is needed, which considers the actual main feedwater isolation times to ensure that environmentally qualified safety related components, required to mitigate the effects of a FWLB inside the MSVV, can perform their safety function prior to being submerged.

Aperiodic Instability of a Once-Through Steam Generator with a Feedwater Line

2006 ◽  
Author(s):  
Jae-Kwang Seo ◽  
Han-Ok Kang ◽  
Juhyeon Yoon ◽  
Keung-Koo Kim
Keyword(s):  
Experimental Data ◽  
Steam Generator ◽  
Pressure Difference ◽  
Flow Instability ◽  
Reverse Flow ◽  
Flow Direction ◽  
Minimum Pressure ◽  
Multiple Flows ◽  
Static Flow ◽  
Aperiodic Instability

Aperiodic (static) flow instability is an instability related to the change of a flow direction in individual steam generating U-shaped channels operating at given pressure difference. The nature of an aperiodic instability is close to a Ledinegg instability [1] related to the presence of multiple flows at the full hydraulic curve of a U-shaped channel. In this paper, the conditions for a reverse flow for a once-through steam generator (OTSG) with U-shaped modular feedwater line (MFL) are studied. From the results of the studies, it is revealed that the change of a flow direction in the MFL is due to the boiling of the feedwater in the downcomer branch of the U-shaped MFL and that multiple flows start in an area of the extremes corresponding to the minimum pressure difference of the hydraulic curves. Calculation models for predicting a threshold of an aperiodic instability for the OTSG of interest is proposed and the analysis results are compared with the experimental data.

Experimental Research on the Influence of Inlet Conditions of Corrugated Plate Dryer

2017 ◽  
Author(s):  
Mao Feng ◽  
Tian RuiFeng ◽  
Chen BoWen ◽  
He Wei
Keyword(s):  
Pressure Drop ◽  
Steam Generator ◽  
Experimental Research ◽  
Separation Efficiency ◽  
Experimental Studies ◽  
Separation Performance ◽  
Separation Mechanism ◽  
Airflow Velocity ◽  
Pressurized Water ◽  
Water Separation

Corrugated plate dryer is one of the key components of natural circulation steam generator in the pressurized water reactor nuclear power plant. It play a decisive role in the water separation system to making steam become a good quality after steam flow out of a vertical steam generator. With the increase of the reactor power in the future design, it requires that the performance of corrugated plate dryer must be increased in the characteristics of steam load, separating efficiency, volume and resistance to make sure that steam generators still produce qualified steam at higher steam loads and higher cycle magnitudes. In this paper, we have done some experimental studies on the corrugated plate dryer. And we concentrated on airflow parameters on the separation performance and resistance performance of dryer. (1) First of all, we have determined the experimental research program about this study, after this, we finished the design works of the test bench, and then we have completed the construction work based on the design works. (2) Afterwards, the flow and separation mechanism of the wave plate dryer was experimentally studied by means of parameter measurement and analysis combined with observation and recording. The effects of different inlet humidities and inlet velocity on separation efficiency, pressure drop and re-entrainment were studied. The above study shows that: (1) The separation efficiency of corrugated plate dryer is related to inlet humidity and inlet airflow velocity. The separation efficiency of corrugated plate dryer is increase with inlet humidity goes higher, and increased to reach a highest point then goes down when inlet airflow velocity increased. (2) The re-entrainment is related to inlet humidity. When inlet humidity increased, the inlet airflow critical velocity which lead to re-entrain would decrease. (3) The pressure drop of dryer is related to the inlet airflow velocity. When the inlet wind velocity increases, the pressure drop increases.

Asymmetry Investigation on Single Phase Flow in Inverted U-Tubes of Steam Generator Under the Condition of Natural Circulation

2010 ◽  
Author(s):  
Chuan Wang ◽  
Lei Yu
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Steam Generator ◽  
Mass Flux ◽  
Single Phase ◽  
Reverse Flow ◽  
Natural Circulation ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Outlet Temperature

In order to study the reverse flow characteristics in U-tubes of steam generator in the natural circulation case, the code RELAP5/MOD3.3 is used to model and calculate single-phase water flow for PWR under some typical operating conditions in the natural circulation case. The U-tubes of steam generator are classified according to their length and then are divided into different nodes and flow lines. The calculated results show that reverse flow exists in some inverted U-tubes of the steam generator, the natural circulation capacity of the primary coolant circuit system declines and the calculated net mass flux of the natural circulation accords with the experimental data. The traditional lumped parameter method can not simulate the reverse flow characteristics in inverted U-tubes and its result is much greater than the experimental data. When the steam generator outlet pressure is higher than inlet pressure, and gravitational pressure drop is lower than the total of frictional pressure drop and area change pressure drop, the reverse flow will occur. As to the nuclear power plant described in this paper, the mass flux of the shorter U-tubes drops more quickly and at last reverse flow will occur. The temperature distribution is uniform in inverted U-tubes, and it is almost identical with that of SG in secondary side. The occurrence of reverse flow can be judged by that whether the steam generator inlet temperature is lower than reactor outlet temperature obviously. It is indicated that reverse flow occurred in the U-tubes of the steam generator reduces the mass flux in the natural circulation system.

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