Calculation of the theoretical plate numbers for HETP and NTP
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I am in the packing trading business. A client has asked about the Sulzer BX500 model of packing; our standard specifications are an HETP of 200 mm, with a theoretical number of theoretical plates ranging from 4 to 5. The standard height produced by manufacturers is 100 or 200 mm. I asked several manufacturers, and they actually only produce the same models; they have no idea about these theoretical values. Could someone explain to me what 200 mm means? How is 4~5 calculated then? The information provided by the client is as follows: The model is Sulzer BX mesh corrugated packing. Outer diameter: 208 mm for 20 layers, 259 mm for 15 layers, 309 mm for 20 layers, and 390 mm for 15 layers. The height in all cases is 170 mm. It is made of SS316L material, with a wire diameter of 0.16 MM. Now the client wants a packing of 170 MM in height and has asked me to help calculate or provide some data – will the HETP and the number of theoretical plates change if the height is 170 MM? Are there any other domestic manufacturers specializing in fillers who can provide technical experts to help solve this problem? I’m eager to learn from others!
The number of theoretical plates is calculated; it represents the amount required to achieve a certain level of separation. Once the customer specifies the system to be separated and the desired separation criteria, this value remains unchanged. Perhaps due to differences among filler manufacturers, there are variations in the fluid dynamic properties and other characteristics of the fillers produced, which results in different HETP values (Height Equivalent of Theoretical Plate, i.e., the equivalent height of a theoretical plate). In simpler terms, the height corresponding to one theoretical plate varies depending on the manufacturer of the filler. HETP changes with the changes in the system; as for the exact extent of this change, it mainly relies on experience. NTSM is the equivalent number of theoretical plates per meter, that is, the number of theoretical plates corresponding to 1 meter of packing. The above is theoretical knowledge; I didn’t quite understand your description, so I’ve explained it based on my own understanding. Your standard parameter is HETP of 200 mm; in other words, the height of the packing material for one theoretical plate is typically set at 200 mm. If 5 theoretical plates are needed to achieve the desired separation effect, then the total height of the packing material will be 1 meter. The disc height is merely a processing height; with 1m of filler, if the disc height is 200, then 5 discs will be required ； If it’s 170, then 6 discs are needed. HETP and the number of theoretical plates do not change with plate height. That’s all I know; I hope it can help you.
Just contact me. Once you see 170mm/disk, you’ll know it’s a Sulzer packing. You can message me on QQ; I’m not sure if the quotation you received refers to the BX500 or the BXPlus