4. Conclusions
A new experimental device is produced, and the hydrodynamics of the
blade unit of the tridimensional rotational flow sieve tray are
experimentally studied. The flow pattern of the unit under different
operating conditions is visually analyzed using the image processing
method. The differential pressure pulsation signals under different flow
patterns of the blade unit are studied in the time and frequency domain,
and the operating domain of the blade unit is clarified. Finally, the
distribution of the rotational and perforated flow for the gas-liquid
phase, which flows through the blade unit, is measured and analyzed. The
following conclusions are obtained.
1) The overflow and spray distributions for the liquid phase are
produced according to the liquid phase arrangement methods. Three flow
patterns are defined under overflow distribution. They are BFF, CPF, and
DMF. Two patterns are defined under spray distribution. They are FJF and
JMF.
2) The time and frequency domain analysis for the differential pressure
pulsation signals corresponding to each flow pattern is carried out. In
the time domain, the increase in the kinetic energy factor of the gas
phase will increase the amplitude of the differential pressure signal.
When the interaction of the gas-liquid is stronger, the fluctuation of
the differential pressure signal is larger. In the frequency domain
under the overflow distribution, the perforation and gas-liquid
interaction intensity changes the values of the main frequencies, and
the variation range is (2.44 Hz–5.4 Hz). Moreover, when the perforation
intensity of the gas phase is higher, the PSD value of the main
frequency is higher. The PSD values are affected by the gas-liquid
mixing strength, when the liquid arrangement method is the spray
distribution. The influence of the airflow on the perforation intensity
is weak, and the variations of the main frequency are stable. Finally,
the operating range of each flow pattern under the two distribution
modes is clarified, according to the changes in the time and frequency
domain of the signal, as well as the results of the image observations
when the flow pattern changes.
3) A rotational flow ratio is introduced to investigate
the distributions of the
rotational-perforated flow for the gas-liquid phase. In the experimental
operating domain, the gas-phase rotational flow ratio is greater than
0.6, and the liquid-phase is less than 0.5. The gas phase through the
blade unit is dominated by the rotational flow, while the liquid phase
is perforated flow. The changes in the rotational flow ratio for the gas
phase under different liquid arrangement methods are similar. The
rotational flow ratio for the gas phase has a turning point when the
liquid film is broken by the airflow. The turning point isF s = 1.6
(m/s*(kg/m3)0.5) (when the
arrangement method is overflow distribution: L W =
26 m3/(m2*h),F s = 2.0
(m/s*(kg/m3)0.5)). Under the
overflow distribution, the sieve holes of the blade unit have a limit in
the flux for the liquid phase, and the spray density corresponding to
the limit will be affected by the gas phase. Finally, a prediction model
for the rotational flow ratio under two liquid arrangement methods is
proposed, and the error is within 10%.