Methodology to Investigate Vibration Phenomena Caused by the Steam Condensation at Subatmospheric Condition

2017 ◽  
Author(s):  
R. Lo Frano ◽  
D. Mazed ◽  
D. Aquaro ◽  
D. Del Serra ◽  
I. Sekachev ◽  
...  
Keyword(s):  
Direct Contact ◽  
Vacuum Vessel ◽  
Nuclear Engineering ◽  
Atmospheric Conditions ◽  
Steam Condensation ◽  
The Past ◽  
Experimental Campaign ◽  
Hydraulic Conditions ◽  
Contact Condensation ◽  
Suppression System

The phenomenon of steam-water direct contact condensation (DCC) was widely investigated in the past because of conventional and nuclear engineering applications, like in the safety suppression system of BWRs. When steam is injected into a sub cooled water, different condensation regimes can be observed, such as chugging, condensation oscillation, bubbling condensation oscillation etc. (these have been identified during the experimental campaign on condensation of steam injected into water at sub-atmospheric conditions carried out at Lab. B. Guerrini of DICI - University of Pisa). According to the thermal hydraulic conditions of the condensing jet plume, vibrations may arise. This paper so deals with the analysis of vibration phenomena that originate during the steam-water direct contact condensation at sub-atmospheric conditions, not treated till today. Numerical investigations (by proper FEM code) as well as experimental activity will be presented and discussed in order to evaluate if vibrations are capable to jeopardise this safety suppression system, which is designed to protect Vacuum Vessel of ITER from pressurizing accidents.

Analysis of Vibrations due to the Steam Condensation at Sub-Atmospheric Condition

2018 ◽  
Author(s):  
G. Giambartolomei ◽  
R. Lo Frano ◽  
D. Mazed ◽  
D. Del Serra ◽  
D. Aquaro
Keyword(s):  
Cooling System ◽  
Numerical Study ◽  
Atmospheric Condition ◽  
Flow Patterns ◽  
Dominant Frequency ◽  
Steam Condensation ◽  
Pressure Oscillations ◽  
Contact Condensation ◽  
Suppression System ◽  
Driving Potential

The condensation of steam in water may cause pressure oscillations, vibrations, and damages to piping and, in some extreme conditions to the internals of suppression tank. Significant R&D activity, especially focusing on the emergency cooling system in BWRs, has been conducted in the past decades to clarify the mechanism of the condensation oscillation evolving/related to the Direct Contact Condensation (DCC). The present paper deals with the pressure oscillations due to the condensation of steam jet in water, at sub-atmospheric condition; phenomena that have not been fully investigated yet. Vibrations, arisen as flow patterns transformed from stable to unstable, are investigated with particular attention to the dynamic behaviour of the whole suppression system, behavior of the interface, flow patterns etc. To the purpose, a numerical study is performed by means of suitable FEM in order to identify the dominant frequency associated to the steam jet condensation oscillation in water flow, and determine the resulting values of pressure and acceleration. The obtained results allowed to formulate a correlation between the dominant frequency and the condensation driving potential and steam mass flux.

Experimental Study of Steam Pressure Suppression by Condensation in a Water Tank at Sub-Atmospheric Pressure

2016 ◽  
Author(s):  
Dahmane Mazed ◽  
Rosa Lo Frano ◽  
Donato Aquaro ◽  
Daniele Del Serra ◽  
Igor Sekachev ◽  
...  
Keyword(s):  
Experimental Study ◽  
Atmospheric Pressure ◽  
High Efficiency ◽  
Saturation Pressure ◽  
Steam Pressure ◽  
Operating Conditions ◽  
Water Tank ◽  
Vacuum Vessel ◽  
Steam Condensation ◽  
Suppression System

The Vacuum Vessel Pressure Suppression System (VVPSS), a key safety system of the ITER plant, is designed to protect the Vacuum Vessel (VV) from over pressure occurring in the case of LOCA (Loss Of Coolant Accident) or other pressurizing accidents such as LOVA (Loss Of Vacuum Accident). The steam condensation in the Suppression Tanks (main elements of the VVPSS system), occurs at sub-atmospheric pressure. The steam condensation, at pressures equal or greater than the atmospheric, has been numerically analyzed and experimentally investigated in the past in order to optimize the design of the pressure suppression system of boiling water nuclear reactors. However, very limited experimental data is available concerning the steam condensation in a water tank at sub-atmospheric pressure. In order to analyze the steam condensation in these operating conditions, an experimental study, funded by ITER Organization, is conducted at the Department of Civil and Industrial Engineering (DICI) of University of Pisa. The tests analyze the condensation of saturated or superheated steam at sub-atmospheric pressures (4.2 kPa and slightly above the water vapour saturation pressure), and pool temperature up to 50°C at several heights of water head. The experimental facility, to perform this study, has been set up with a significant scaling factor regarding the full size installation at ITER. In this paper the experimental rig, the conditions of the experiments, and the test matrix are presented. The temperature and pressure measurements with details of the data acquisition system are described. The tests were performed at different patterns of the sparger exit holes (1, 3 and 9) and for three steam mass flow rates per one hole. The results show very high efficiency of condensation for all examined conditions. Finally, a comparison between the condensation regimen at sub-atmospheric and at atmospheric pressure is discussed.

Semi-batch and continuous production of Pickering emulsion via direct contact steam condensation

Soft Matter ◽  
2021 ◽  
Author(s):  
Nithin Madhavan ◽  
Eswararao Yalla ◽  
S. Pushpavanam ◽  
T. Renganathan ◽  
Manas Mukherjee ◽  
...  
Keyword(s):  
Direct Contact ◽  
Continuous Production ◽  
Pickering Emulsion ◽  
Steam Condensation ◽  
Conventional Methods ◽  
Contact Condensation

We propose a versatile strategy for the production of highly stable water in oil Pickering emulsion by direct contact condensation of steam. In contrast to conventional methods that use of...

DIRECT CONTACT CONDENSATION OF FLOWING STEAM ONTO INJECTED WATER

1978 ◽  
Author(s):  
Shigebumi Aoki ◽  
Akira Inoue ◽  
Yoshiyuki Kozawa ◽  
H. Akimoto
Keyword(s):  
Direct Contact ◽  
Contact Condensation

Reduce odor and NH3 emission: condensation of the carbonatation vapors

2017 ◽  
pp. 534-537
Author(s):  
Nico Antens ◽  
Jan L.M. Struijs
Keyword(s):  
Direct Contact ◽  
Waste Heat ◽  
Pilot Scale ◽  
Sugar Production ◽  
Two Stage ◽  
Indirect Contact ◽  
Nh3 Emission ◽  
Emission Limits ◽  
Plant Trials ◽  
Contact Condensation

At beet sugar production, vapors from first and second carbonatation contain a significant amount of odor components, NH3 and waste heat, which are normally directly released into the environment. Due to sustainability motivations, obligations regarding odor nuisance and expected stricter regulations regarding NH3 emission limits, Suiker Unie decided to take measures to reduce emission via the carbonatation vapors. During the 2015 beet campaign, pilot scale plant trials have been performed to investigate the effectiveness of indirect contact and direct contact condensation of these vapors. Based on this experimental work a two-stage gas scrubbing concept was designed: in the first stage main goal is condensing the vapors and reuse the heat of condensation to heat up limed juice, while the actual scrubbing takes place in the second scrubber. This two-stage gas scrubbing installation has been built at the Vierverlaten factory and was started up in the 2016 beet campaign. The background, pilot scale trials, concept of design and achieved reductions in odor and NH3 emission at industrial scale are discussed.

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