Spray density of the packed tower

Still don’t understand how to calculate the spraying density or what values to use

If the liquid spray density reaches 22, it becomes less meaningful to use wire mesh packing at this point; a high liquid spray density results in a thicker liquid film on the surface of the packing. It is recommended to use metal perforated plate corrugated packing.

The liquid spray density for the packed tower is 22; it’s fine to use mesh packing. You just need to calculate the fluid flow rate based on this spray density, and then determine the number of distribution points per square meter for the selected mesh packing – 200 points per square meter for the BX500 type, and 300 points per square meter for the CY700 type. Once the number of distribution points is known, you can calculate the diameter of the distribution holes. The minimum spray density is 0.2, but this is merely a guideline; in reality, a density of only 0.2 is too low, as it makes it difficult to achieve even distribution of the liquid. Therefore, a spray density of 22 is appropriate for you.

An excessive spray density affects the efficiency of the packing; if its use is insisted on, ensure an appropriate margin is left. It seems the third floor has experts in this field.

Liquid spray density refers to the volume of liquid sprayed per unit time per unit cross-sectional area of the tower, denoted by U, with the unit of m3/(m2·h). To ensure adequate wetting of the packing layer, it is necessary to maintain a liquid spray density above a certain limit value; this limit value is known as the minimum spray density. The minimum wetting rate refers to the minimum volume flow rate of liquid per unit length around the packing at a given cross-section of the tower. Its value can be calculated using empirical formulas or empirical values. For bulk packing with a diameter of 75 mm or less, the minimum wetting rate (LW)min can be taken as 0.08 m3/(m·h) ； For bulk packing with a diameter greater than 75 mm, take (LW)min = 0.12 m3/(m·h). The wetting performance of the filler surface is related to its material; among the commonly used materials of ceramics, metals, and plastics, ceramic fillers have the best wetting performance, while plastic fillers have the worst. The liquid spray density used in actual operation should be greater than the minimum spray density. If the spray density is too low, the liquid flow rate can be increased by raising the reflux ratio or by using liquid recirculation, in order to ensure adequate wetting of the filler surface ； Reducing the tower diameter can also be used as a compensation measure ； For fillers made of metal or plastic, surface treatment methods can be employed to improve their surface wettability.

Screen packings have a relatively large specific surface area, allowing for a smaller gas phase kinetic energy factor. Too high a spray density can easily lead to flooding. As long as flooding does not occur during operation, there are no other effects, nor will it affect gas-liquid mass transfer. However, the design of the distributor is likely not capable of handling such an increase in liquid flow; it will be necessary to redesign the number and diameter of the distribution holes in the liquid distributor, and even the type of distributor itself may need to be changed.

The spray density is primarily determined by the specific surface area of the filler; for diameters of 75 mm or less, the wetting rate is 0.08 m3/s. Based on the above data, the spray density required for different fillers can be calculated.

Spray density and spray point density are not the same concept, right?

Thank you, I agree with the person above!

I’m currently learning *; I hope everyone will share more with me. Hehe