Numerical Simulation of New Axial Flow Gas-Liquid Separator

At present, most of the incoming liquids from the oilfield combined stations are not pre-separated for natural gas, which makes the subsequent process of oil-water separation less effective. Therefore, it is necessary to carry out gas-liquid separation. A new type of axial flow gas-liquid separator was proposed in this paper. The numerical simulation was carried out by CFD FLUENT software, and the changes of concentration field, velocity field and pressure field in the axial flow gas-liquid separator were analyzed. It was found that there were gas-liquid separation developments and stabilization segments in the inner cylinder of the separator. The axial velocity will form a zero-speed envelope in the inner cylinder, and the direction of the velocity in front of and behind the zero-speed envelope was opposite. The tangential velocity showed a “W” shape distribution in the radial position of the inner cylinder. The pressure on the left wall of the guide vane was higher than that on the right side. Therefore, the left wall was more likely to be damaged than the right wall.

Effects of Removal Conditions on Mercury Amount Remaining in the Oral Cavity and inside Drainage System after Removing Dental Amalgams

Mercury is produced and drained into the environment by removing dental amalgams, which may cause mercury pollution. This study aimed to clarify the mercury amount remaining in the oral cavity and inside the drain system after removal. The effects of the removal conditions and differences in drainage systems were also investigated. Dental amalgams filled in the tooth and placed in a phantom head were removed using an air turbine under several conditions (two removal methods, absence of cooling water, and intraoral suction). Then, the oral cavity was rinsed with 100 mL of water (oral rinse water), and 500 mL of water was suctioned to wash the inside of the drainage system (system rinse water). Both water samples were collected in two ways (amalgam separator and gas-liquid separator), and their mercury amounts were measured. It was found that the amount of mercury left in the oral cavity and drainage system after dental amalgams removal could be reduced when the amalgams were removed by being cut into fragments as well as using cooling water and intraoral suction. In addition, using amalgam separators can significantly reduce the amount of mercury in the discharge water and prevent the draining of mercury into the environment.

Feasibility Study on Downhole Gas–Liquid Separator Design and Experiment Based on the Phase Isolation Method

As oil exploitation enters its middle and late stages, formation pressure drops, and crude oil degases. In production profile logging, the presence of the gas phase will affect the initial oil–water two-phase flowmeter’s flow measurement results. In order to eliminate gas-phase interference and reduce measurement costs, we designed a downhole gas–liquid separator (DGLS) suitable for low flow, high water holdup, and high gas holdup. We based it on the phase isolation method. Using a combination of numerical simulation and fluid dynamic measurement experiments, we studied DGLS separation efficiency separately in the two cases of gas–water two-phase flow and oil–gas–water three-phase flow. Comparative analysis of the numerical simulation calculation and dynamic test results showed that: the VOF model constructed based on k−ε the equation is nearly identical to the dynamic test, and can be used to analyze DGLS separation efficiency; the numerical simulation results of the gas–water two-phase flow show that when the total flow rate is below 20 m3/d, the separation efficiency surpasses 90%. The oil–gas–water three-phase’s numerical simulation results show that the oil phase influences separation efficiency. When the total flow rate is 20 m3/d–50 m3/d and gas holdup is low, the DGLS’s separation efficiency can exceed 90%. Our experimental study on fluid dynamics measurement shows that the DGLS’s applicable range is when the gas mass is 0 m3/d~15 m3/d, and the water holdup range is 50%~100%. The research presented in this article can provide a theoretical basis for the development and design of DGLSs.

A Compact Gas Liquid Separator for the SNS Mercury Process Loop

Upgrades at the Spallation Neutron Source (SNS) accelerator at Oak Ridge National Laboratory are underway to double its proton beam power from 1.4 to 2.8 MW. About 2MW will go to the current first station while the rest will go to the future Second Target Station. The increase of beam power to the first target station is especially challenging for its mercury target. When the short proton beam hits the target, strong pressure waves are generated, causing cavitation erosion and challenging stresses for the target's weld regions. SNS has successfully operated reliably at 1.4 MW by mitigating the pressure wave with the injection of small Helium bubbles into the mercury. To operate reliably at 2MW, more gas will be injected into mercury to mitigate the pressure wave further. However, the mercury process loop was not originally designed for gas injection, and the accumulation of gas in the pipes is a concern. Due to space constraints, a custom Gas Liquid Separator (GLS) was designed to fit a 90-degree horizontal elbow space in the SNS mercury loop. Simulations and experiments were performed, and a successful design was developed that has the desired efficiency while keeping the pressure losses acceptable.

Research on the Performance of a Passive Gas-Liquid Separator Used in Space

Gas-liquid separation technology is one of the key technologies of environmental control and life support in manned spaceflight. In order to realize gas-liquid separation under microgravity, a prototype of a gas-liquid separator based on passive static separation technology was designed, manufactured, and studied by both ground experimental tests and computational fluid dynamics (CFD). Results show that the experimental results on earth are in good agreement with the simulation results and the internal fluid distribution directly determines the separation rate of the separator. The separation rate and internal flow field of the separator were also investigated under various flow rate conditions and gravity levels. Results show that higher liquid flow rate and lower gravity level can improve gas-liquid separation rate which attributes to the formation of a complete liquid film at the bottom of the collector. The separation rate can reach 100% within the specific ratio range, and the structure of the equipment is simple, without any power components, meeting the requirements of long life and high reliability of space equipment. It can provide a reference for gas-liquid separation in space under the microgravity environment.