Stripping (chemistry)

We can clean dirty liquids.

One way is to use gas. The gas moves bad things out. This is called stripping.

Liquid goes in at the top. The gas goes in at the bottom. They meet inside a tall tower.

Inside, there are trays or small pieces.

These trays help the gas and liquid touch. The gas bubbles through the liquid. This helps pull the bad parts away. It makes the liquid clean.

People use steam or air to do this. This helps clean water and soil. It keeps our world safe.

Stripping is a way to clean liquids. It uses a gas stream to pull parts out of a liquid. This is called mass transfer. This means a part moves from the liquid into the gas.

Most stripping happens in tall towers. These towers can be trayed or packed. In a trayed tower, liquid flows in at the top. The gas enters at the bottom. Inside, there are plates called trays. These trays make the liquid move back and forth. They also make the gas bubble up through holes. This helps the gas and liquid touch more.

Packed towers do not use trays. Instead, they use packing. Packing is a set of small parts inside the tower. These parts also help the gas and liquid touch. One kind of packing is called Białecki rings.

People use stripping to clean the Earth. They use steam or air as the gas. This can clean soil from harbors. It can also clean water. This helps remove harmful things from our water and soil.

Stripping is a clever way to separate things. It is a physical process used in many industries. It works by using a gas stream to remove parts from a liquid. This movement is called mass transfer. The gas and liquid meet at a boundary called an interface. A specific part, called a solute, moves from the liquid into the gas. This movement is known as the flux of A.

Most stripping happens inside tall columns. These columns can be trayed or packed. In a trayed tower, liquid enters at the top. The vapor enters at the bottom and moves up. Inside, metal or plastic trays force the liquid to flow sideways. The vapor bubbles up through holes in these trays. This creates a large contact area between the two flows.

Packed columns work in a slightly different way. They do not use trays to create contact. Instead, they use materials called packing inside the tower. This packing can be structured or random. Random packing is often used in smaller columns. These columns might be less than 2 feet wide. They should also not be more than 20 feet tall.

Scientists and engineers have developed many types of packing. Older versions included ceramic Raschig rings and Berl saddles. Newer materials include metal or plastic Pall rings. There are also ceramic Intalox saddles. One special kind is the Białecki ring. These were described in Polish Patent 101135 in 1976. These newer designs help increase the surface area. They also help the liquid flow more evenly.

Stripping is very helpful for protecting our world. It can remove harmful contaminants from waste. For example, steam can clean soil from harbors. This helps remove TBT and PAH from dredged sediments. Steam is also used to treat water. It removes volatile organic compounds from groundwater and wastewater. This keeps our water and soil much cleaner.

Stripping is a vital physical separation process used in many industrial settings. It works by removing one or more specific components from a liquid stream. To do this, a vapor stream is passed through the liquid. This process relies on a principle called mass transfer. Mass transfer occurs when a component, often called a solute, moves from the liquid phase to the vapor phase. For this to happen, the substance must cross a gas-liquid interface. The total amount of the substance that moves across this boundary is known as the flux of A.

Engineers design stripping columns to maximize this mass transfer. The liquid and vapor streams can flow in two different ways. They might move in a co-current flow, where both travel in the same direction. Alternatively, they can move in a countercurrent flow, where they travel in opposite directions. Most industrial stripping is performed inside tall vertical columns. These columns are typically either trayed towers or packed columns. They can also occasionally be done in spray towers, bubble columns, or centrifugal contactors.

Trayed towers, also known as plate columns, use internal structures to work. In these towers, the liquid flows in at the top and exits out the bottom. The vapor phase enters at the bottom and exits through the top. Inside the column, there are several trays or plates. These trays force the liquid to flow back and forth horizontally. At the same time, the vapor bubbles up through holes in the trays. This specific movement increases the contact area between the liquid and the vapor.

Trays can be designed as sieve trays, valve trays, or bubble cap trays.

Packed columns offer a different method for achieving separation. Like trayed towers, the liquid and vapor enter and exit in the same way. However, packed columns do not contain trays. Instead, they are filled with various types of packing material. This packing is used to increase the contact area between the two phases. Packed columns are often preferred for smaller operations. This usually applies to columns with a diameter of less than 2 feet and a height of no more than 20 feet. They are also useful for handling corrosive or high-foaming fluids.

There are many different types of packing materials available. Engineers choose them based on surface area, flow area, and pressure drop. Older generations of packing included ceramic Raschig rings and Berl saddles. Newer, more common materials include metal and plastic Pall rings. There are also ceramic Intalox saddles. One notable example is the Białecki ring, which was described in Polish Patent 101135 in 1976.

Modern packing is designed to prevent materials from stacking on top of each other. If packing stacks, it drastically reduces the available surface area for mass transfer.

Designing a stripper requires managing many different variables. Engineers must consider the entering conditions and the required degree of recovery. They must also choose the right stripping agent, such as steam, air, inert gases, or hydrocarbon gases. The choice of agent depends on solubility, stability, cost, and corrosiveness. To minimize flow, operators often work at high temperatures and low pressures. It is also important to manage the size of the equipment. If the column is too large, flow channeling can occur. This is when the liquid does not spread out evenly. If this happens, a redistribution plate is used to reestablish the contact area.

Stripping plays a massive role in environmental protection and remediation. It is frequently used to remove harmful contaminants from waste streams. For example, steam stripping can be used to clean harbor soils. Contaminated soils are dredged and mixed with water to create a slurry. Steam is then used to strip contaminants like TBT and PAH from the mixture. This process can decontaminate soils almost completely.

Additionally, steam is used in water treatment. It removes volatile organic compounds from groundwater and wastewater. This is essential because these compounds are often present due to industrial or agricultural activities.