What Is a Degasser?
A degasser is a device that removes gases from water.
Normally, water contains oxygen and carbon dioxide from the atmosphere. These gases in water can change the taste and color of drinking water, interfere with chemical reactions, and lead to rust in pipes.
Degassers come in a variety of sizes, including large degassers used in factories for manufacturing and refrigeration, and small degassers used in laboratories.
Uses of Degassers
Because degassers remove oxygen and carbon dioxide from water, they are used in a variety of industries that handle water. For example, in the beverage and food industries, the dissolved oxygen in water directly affects the color and taste of products, so the water used is de-aerated.
Piping used to transport hot water, or steam is also often degassed as dissolved oxygen can cause rust. Other small degassers are also used in research and development.
For example, they are used to degass water used in chemical reactions or in analytical equipment such as high performance liquid chromatography (HPLC). Degassing is especially essential for devices such as HPLC that use a pump to keep water flowing, as air bubbles can cause pulsations in the pump.
Principle of Degassers
The principle of the degassing process is based on the law that the amount of gas dissolved in a liquid is proportional to the pressure on the gas side. Therefore, if a liquid and a gas are in contact, lowering the pressure on the gas side will reduce the amount of gas dissolved in the liquid. To put it extremely simply, if a vacuum is created, the amount of gas dissolved in the liquid will be reduced to zero.
In addition, the wider the surface where the liquid and gas come into contact with each other, the more efficient the degassing process will be. Simply increasing the diameter of the device will increase the surface where the liquid and gas come into contact, thereby improving the degasser’s performance, but the device itself will become larger and more costly.
As a countermeasure, the use of hollow fibers is effective. The surface where the liquid and gas come into contact with each other can be expanded, making it possible to degasser efficiently in relation to the size of the device. There are two methods of degassing in degassers: the tank method removes gas from a liquid by depressurizing the inside of the tank.
The degassing process varies in proportion to the size of the tank. The other method is the vacuum deaeration tower method, in which degassing is performed by depressurizing the liquid injected in particulate form. Since the liquid is in particulate form, the surface in contact with the liquid and gas is dramatically increased compared to the tank method, resulting in better degassing. However, the vacuum degasser method is expensive to install and requires large equipment.
Features of Degassers
Atmospheric oxygen and carbon dioxide dissolve in water in minute quantities. Since the amount of dissolved oxygen and carbon dioxide is minute, there is no problem when using small amounts of water, but in factories and other places where large amounts of water are used, dissolved oxygen and carbon dioxide can cause unexpected problems. For example, oxygen oxidizes metals, causing rust in pipes. In the food and beverage industry, oxidation caused by dissolved oxygen can change the color and taste of products.
Degassers remove such dissolved oxygen and carbon dioxide. The degasser is equipped with a vacuum pump and a degasser membrane, and water flows through a channel covered by the degasser membrane. Because the flow path is depressurized by the pump, only small molecules, such as dissolved oxygen, pass through the membrane as they pass through the flow path. As a result, gases are removed from the water that is passed through the membrane.
Degassers can also degas liquids other than water, such as organic solvents. However, it is necessary to check the durability of the membrane against the solvent to avoid swelling or dissolving the membrane. Also, in the case of mixed solutions, it is necessary to confirm that the solution composition is not changed by passing through a line under reduced pressure.