Purification Technology Edition Daily Question (Short Answer) [2018-2-21]

Functions and characteristics of the packing in the tower: The packing provides a sufficient contact surface for the gas-liquid phases, and creates conditions to enhance the turbulence in the gas phase, thereby facilitating mass and heat transfer. Its features are: a large gas-liquid contact area, a high mass transfer coefficient, high throughput, and low resistance.

Role of the packing in the tower: The packing provides a sufficient contact surface for the gas-liquid phases, and creates conditions to enhance the turbulence in the gas phase, thereby facilitating mass and heat transfer. Its features are: a large gas-liquid contact area, a high mass transfer coefficient, high throughput, and low resistance.

Column packing refers to the packing used in packed columns; its role is to provide a sufficient contact surface between the gas and liquid phases, and to create conditions that enhance turbulence (mainly in the gas phase), thereby facilitating mass transfer (including heat transfer). A packed tower is a mass transfer device that uses the packing inside the tower as the contact element between the gas and liquid phases. The tower body of a packed tower is an upright cylinder, with a packing support plate at its bottom; the packing is placed on this support plate either in a random pile or in an organized manner. A packing plate is installed above the packing to prevent it from being blown by upward airflow. The liquid is sprayed from the top of the tower via a liquid distributor onto the packing, and flows down along the surface of the packing. Gas is fed in from the bottom of the tower; after being distributed by a gas distribution device (which is generally not used in towers with small diameters), it flows counter-currently to the liquid through the gaps in the packing layer. On the surface of the packing, the gas and liquid phases come into close contact, enabling mass transfer to occur. A packed tower is a type of continuous-contact gas-liquid mass transfer device, in which the composition of the two phases changes continuously along the height of the tower. Under normal operating conditions, the gas phase acts as the continuous phase, while the liquid phase is the dispersed phase. As the liquid flows downward through the packing layer, it tends to concentrate toward the tower wall, resulting in an increasing flow rate of liquid near the wall; this phenomenon is known as wall flow. The wall flow effect causes uneven distribution of the gas-liquid phases in the packing layer, thereby reducing the mass transfer efficiency. Therefore, when the packing layer is high, it needs to be segmented, with a redistribution device installed in between. The liquid redistribution device consists of a liquid collector and a liquid redistributor. The liquid that flows down from the upper packing is collected by the liquid collector and then sent to the liquid redistributor, where it is redistributed before being sprayed onto the lower packing. Packed towers have advantages such as high production capacity, high separation efficiency, low pressure drop, low liquid holdup, and great operational flexibility. Packed towers also have some disadvantages, such as the high cost of the packing ； When the liquid load is low, it cannot effectively wet the surface of the packing, resulting in a reduced mass transfer efficiency ； It cannot be used directly with materials containing suspended solids or those prone to polymerization ； Complex distillations such as counter-current feeding and discharging are not very suitable for this purpose

The function of the packing inside the tower is to provide a sufficient contact surface between the gas and liquid phases, and to create conditions that enhance turbulence (mainly in the gas phase), thereby facilitating mass and heat transfer. Packed towers have advantages such as high production capacity, high separation efficiency, low pressure drop, low liquid holdup, and great operational flexibility.

1: High efficiency in heat and mass transfer. (1) The stainless steel wire mesh packing specifically designed for efficient methanol distillation that we use has a large specific surface area per unit volume, which enhances the basis for heat and mass transfer through contact between the gas and liquid phases. (2) The theoretical number of theoretical plates for stainless steel mesh packing designed for efficient methanol distillation is much higher than that of a plate column of the same height, which increases the effective mass and heat transfer area of the column and allows the column height to be reduced by about 1/3. (3) Due to the rational arrangement of the filler surface, dry zones on the filler surface are prevented; at the same time, the internal components of the tower facilitate uniform flow of both gas and liquid phases within the filler layer and promote surface renewal of these phases. As a result, the effective area of the filler surface available for mass transfer increases, leading to higher overall average mass transfer coefficients and driving forces. (4) The stainless steel wire mesh packing designed for methanol distillation in our company, after being treated with special solvents, has a good wettability to the liquid phase, which facilitates even distribution of the liquid. II: Low pressure drop and high gas-liquid mass transfer rate. (1) The new type of packing has a high porosity, resulting in a low pressure drop and high mass transfer rate. (2) New filler channel design, with low liquid holding capacity and low resistance. (3) The new type of filler has sufficient strength due to special reinforcement treatments. Therefore, during installation, it is difficult for the surface of the packing to deform and cause changes in the flow path. III: Even liquid distribution. Due to the angle between the flow channels on the mesh sheets and the axis, the angles of the flow channels on adjacent sheets are in opposite directions. Moreover, the upper and lower layers of packing fit closely together and are arranged at 90 degrees to each other, which helps the liquid to be redistributed after passing through each layer, resulting in a more even distribution. This enhances the ability to distribute the liquid evenly, thereby providing excellent mass and heat transfer capabilities.

The function of the packing inside the tower is to provide a sufficient contact surface between the gas and liquid phases, and to create conditions that enhance turbulence (mainly in the gas phase), thereby facilitating mass and heat transfer. Packed towers have advantages such as high production capacity, high separation efficiency, low pressure drop, low liquid holdup, and great operational flexibility

Its function is to act as an absorber. Features: 1. It is a mass transfer device that uses the packing inside the tower as the contact element between the gas and liquid phases. 2. Packing towers have advantages such as high production capacity, high separation efficiency, low pressure drop, low liquid holdup, and great operational flexibility.

Role of the packing in the tower: The packing provides a sufficient contact surface for the gas-liquid phases, and creates conditions to enhance the turbulence in the gas phase, thereby facilitating mass and heat transfer. Its features are: a large gas-liquid contact area, a high mass transfer coefficient, high throughput, and low resistance.

Functions and characteristics of the packing in the tower: The packing provides a sufficient contact surface for the gas-liquid phases, and creates conditions to enhance the turbulence in the gas phase, thereby facilitating mass and heat transfer. Its features are: a large gas-liquid contact area, a high mass transfer coefficient, high throughput, and low resistance.

To provide a sufficient contact surface between the gas and liquid phases, and to create conditions that enhance the turbulence in the gas phase, thereby facilitating mass and heat transfer. Its features are: a large gas-liquid contact area, a high mass transfer coefficient, high throughput, and low resistance.