Vapor-assisted cavitation and 2-phase flow through commercial distributor grid geometries

点击翻译按钮获取中文摘要

Within the oil and gas upgrading industry there is a technology allows for some of the heaviest oil to be upgraded into products that can eventually be converted into gasoline, plastics, and other useful products. Unlike traditional coking which produces carbon containing heavy metals and sulphur, this alternative technology works by adding hydrogen and breaking some of the largest molecules into smaller pieces, making the oil more usable without forming a solid coke byproduct. This technology is called hydrofining or hydroprocessing, and has several different names (LC-Finer, H-Oil, etc.). A challenge currently faced within this technology is the accumulation of too much gas inside the unit during operation. As the heavy oils are broken down, they evaporate and form a gas that flows inside the system along with hydrogen. These units struggle to remove this gas (which is also the product), which can lead to desired products being broken down too much (forming less useful products). As a result, as much as 40% of the volume inside these systems can be filled with gas, reducing the ability of the technology to process liquid fuels and increasing the energy required to make heavy oils usable. Even a small reduction in gas (as little as 1%) can mean millions of dollars in saved energy cost and increased productivity a year within these systems. Despite several attempts using both experiments and computer simulations, efforts to improve the way we remove this gas have not been overly successful. At the high temperature and pressure in these systems, the gas is present as very small bubbles (roughly half a millimetre), and the presence of different contaminants makes it very tough for these bubbles to join together, almost forming a stable "foam". This makes them extremely difficulty to remove. Instead of looking to remove these bubbles, the focus of this work is to better understand how the smallest of these bubbles initially form. By eliminating the smallest sized bubbles, separation of this gas becomes easier and significant energy savings could be realized. This project attempts to look at some of the smallest flow paths of liquid and gas in this system by creating very thin geometries in a lab with similar flow behaviour as seen in a full-scale industrial unit. This allows for the gas and liquid flow behaviour and bubble generation to be viewed with a high-speed camera, as well as collection of information that lets us understand how the smallest bubbles are formed. By using this information to train computer simulations, we can predict how changing the smallest elements of the hydrofining reactor can have a big impact on its operation and the energy required to make Canada's heavy oil resources viable. The results of this work is also applicable to other chemical industries as well as water treatment and aquaculture, potentially leading to benefits beyond the oil and gas industry.