*2.1. TST Space Barrier Drainage Principle*

The TST consists of three parts: a tray with a plate hole, a spray tube above the plate hole, and a liquid sealing cap. The structure is shown in Figure 2.

By setting a layer of tray every 350 mm, the liquid will not accumulate obviously near the wall with increasing tower height in the sloshing state. At the same time, because of the gas–liquid countercurrent contact, the liquid does not need to cross the whole tray. The problem with the traditional plate tower where the partitions cannot be increased in the flow direction to reduce the sloshing effect can be solved here by increasing the partitions. The effect of the partitions is shown in Figure 3.

**Figure 3.** The effect of the partitions. (**a**) Form of the partitions; (**b**) working principles of the TST.

#### *2.2. Experimental Setup and Process*

The spray tube of the TST has the function of dropping liquid. Thus, the maximum characteristic of the TST is that there is no independent liquid-receiving plate or liquid drop area on the tray, giving the TST the features of structural symmetry in all horizontal directions. Therefore, this paper only studied the influence of the most influential sloshing (rolling) on the hydrodynamic performance of the TST. To simplify the experimental setup, only one barrier unit was analyzed in this experiment, and the diameter of the tower used was 400mm, that is, λ = 400 mm. Mobil presented a model wave experiment of the FPSO device in 1998, which showed that under severe sea conditions, the hull roll did not exceed 6◦. Han et al. [32] pointed out that the maximum amplitude of rolling or pitching is 5.15◦ under the once-in-a-century combination of wind and waves along the coast of China. Through the relevant research, it is found that the sloshing period is mostly between 6 s–20 s with regard to the influence of offshore sloshing on the tower. Therefore, combined with experimental conditions, the rolling experiment was carried out at 0–7◦ and for rolling periods of 8s, 12s, 16s, and 20s. The gas flow velocity and liquid flow were selected from the normal operating conditions in the static state. The experimental conditions are shown in Table 1.

**Table 1.** Experimental conditions.


The experimental setup is shown in Figure 4. It consists of a tower, a blower, a circulating pump, a measuring device, and a sloshing platform. The experimental tower used in the experiment was composed of organic glass and PPR (pentatricopeptide repeats) material, with a diameter of 400 mm, a tray spacing of 350 mm, and two fixed TSTs with a diameter of 90 mm. On the spray tube side wall of the TST, 231 holes with a diameter of 8 mm were opened, and 12 half-holes with a diameter of 8 mm were opened on the bottom. The experimental tower was placed on a circulating water tank with a diameter of 600 mm. The highest plate was used to collect entrained liquid. The lowest plate was used to collect weeping liquid. The experimental tower and the circulating water tank were connected to the sloshing platform to slosh together with the sloshing platform. The sloshing platform is shown in Figure 5.

The TST hydrodynamic experiment was carried out under ambient temperature and pressure using an air–water system. During the experiment, gas from an air blower, driven by a frequency conversion motor with 5 kW rated power, was introduced into the bottom of the tower. The velocity of the gas was measured using a pitot tube flowmeter. After the air contacted the liquid phase from bottom to top, it was removed from the vent after passing through the entrainment collector. The water was pumped out by a circulating pump from a circulating water tank and entered from the top of the tower after the rotameter measured the flow. The sloshing platform was controlled by electric machinery to achieve different amplitudes and periods of rolling. The tray pressure drop was measured using a ZCYB-1000 electronic differential pressure gauge, which has an accuracy margin of 1 Pa. After the operation reached stability, the rolling origin was selected as the starting point to start timing, and the pressure drop value was recorded every quarter-period. At the same time, the weeping and entrainment rates were calculated by collecting the weeping liquid and entrained liquid droplets within a certain time in a graduated cylinder. The height of clear liquid could be read from the ruler at the detection point of the tower wall, with an accuracy margin of 1 mm.

**Figure 5.** Sloshing platform.
