Drills are a vital component among the various equipment utilized in shaping and fabricating metal and hard material products. However, like anything that involves friction, drills can create a significant amount of heat if unaddressed. Instead, modern equipment utilizes drilling fluid to lubricate the contact point of drill bits and to flow away debris created in the drilling process. However, even the drilling fluid itself creates risks to products that have to be addressed, particularly the removal of gases in the drilling fluid itself.

In this post, the experts from Connors Industrial will cover what a degasser is and how it works.

The Degasser Function

A degasser is intended to clean or filter drilling fluid of tiny gas bubbles that otherwise can be created by freeing material from the drilling target or the drilling process. This is a serious matter when drilling into the material under pressure as the atmosphere expands as it rises and frees up. Without removal, the fast expansion of such gases can create hazards, even severe environmental risks to personnel and equipment in the immediate release area of the gas. Imagine what happens when molten steel, for example, starts bubbling hard and splashing!

Common gas problems in drilling fluid include bubbles becoming entrapped, for example, in the drilling system's choke manifold or flow line. Instead, the gas bubble is diverted into a separator with a degasser. This allows the gas bubble removal from the drilling fluid and maintains the safety of the equipment being operated without unexpected pressure blows, damage or kicks thanks to the gas release.

Other options, such as homemade filters and switch tanks, don’t work well. Instead, they frequently let smaller bubbles through, especially when fully encapsulated by the drilling fluid versus floating on the surface. Gases can typically include everything from carbon dioxide to methane, especially when pulling fluid from material that is in natural forms, such as earthbound targets or rock.

Types of Degasser Equipment Used

Types of degassers include vacuum tank degassers and atmospheric degassers. The vacuum type tends to be the design most folks are familiar with or have seen and operated if working with drilling fluid. The drilling fluid moves through a containment system that includes baffles and, similar to break up clumps and thickness that traps bubbles, providing a vacuum effect that pulls bubbles out of the fluid. 
Gas captured is then discharged through a separate venting or flaring function.

In steel production, vacuum degassing is the primary method for gas bubble removal. It is typically applied right after the primary, the first melt has been affected. The goal is to account for atmospheric pressure that otherwise occurs in molten steel above the hot metal versus in it. Again, bubbles coming up with immediate or speedy release can be risky, even explosive, with hot metal and extreme temperatures. Instead, with a vacuum degasser applied to the furnace, bubbles are captured and released versus open release in open-top furnace containers.

Alternatively, vacuum work can be applied in the ladle used for moving and pouring the molten metal. Utilizing a stirring movement agitator, the steel begins to release bubble gasses toward the surface as they percolate up and out with movement. Doing so improves the integrity and commonality of the metal itself and removes gaps or gas holes in the mix (also potentially including contaminants). The vacuum degassing method is not perfect. About half of 50 percent of the gas bubbles trapped will be removed.

Atmospheric degassers move fluid via pressure through impellers and baffles to break up fluid thickness and force bubbles to rise. Eventually, the freed bubbles escape out and are vented through an exhausting process, separated from the drilling fluid, returning to use clean and usable.

A third type involves centrifugal degasser designs, which essentially spin a gravity via centrifugal force. Bubbles float up and out by their natural buoyancy while heavier drilling fluid stays lower. Then the bubbles are skimmed off and released.

In comparison, vacuum degassers provide a better output for the time, equipment and energy involved. However, they lose their advantage with high flow application, favouring lower flow speeds and capacity.

Another thing to remember is that a degasser doesn’t work by connecting it to a pumped circuit. It actually needs to have at least two if not more pumps involved, one moving fluid to the drill and the other carrying the fluid through the degasser component.