Author：Huamo Water treatment materials FROM：Water filter membrane manufacturer TIME：2021-09-08
1. Pressure drop of hollow fiber ultrafiltration membrane
The pressure drop across the uf membrane module is the pressure difference between the supply liquid at the inlet and outlet of the module and the extraction liquid. The pressure drop is closely related to the water flow of the source liquid, the flow rate at the membrane surface after the raw liquid enters the uf membrane module and the consumption of concentrated water. Especially with hollow fibre modules with internal pressure plates or capillary type ultrafiltration membranes, the working pressure and flow rate at the membrane surface will gradually change with the direction of the flowing water.
As the source fluid flow rate, flow rate and concentrate water consumption consumption increase, the pressure drop increases, which can result in the working pressure at the mid and downstream membrane surfaces not reaching all the normal working pressures required and therefore the total water flow through the hollow fiber ultrafiltration membrane can be compromised. During specific operations, the pressure drop value should be controlled as much as possible and not allowed to become too high. As the module runs for a longer period of time, more and more residue will build up on the inner wall of the membrane, a situation that increases the frictional resistance of the flowing water and causes the pressure drop in the membrane module to expand, seriously jeopardising all normal operation of the hollow fiber ultrafiltration membrane. Timely cleaning of the membrane modules can be a good solution to such problems.
2.The hollow fiber ultrafiltration membrane working pressure analysis
In the general treatment of aqueous solutions, hollow fiber ultrafiltration membrane operate at pressures ranging from 0.1 to 0.6 MPa. Naturally, depending on the relative molecular mass of the chemical aqueous solution, the working pressure will of course vary depending on the choice of ultrafiltration membrane filter to cut off the residues in the aqueous solution. Generally for hollow fibre internal pressure membranes with plastic shells, the tensile strength of the shell is 0.3 MPa and the compressive strength of the hollow fibre is less than 0.3 MPa, so the working pressure of hollow fibre membranes with plastic shells should be less than 0.5 MPa. Super heavy duty hollow fibre ultrafiltration membranes have a high compressive strength of up to 0.6 MPa, but the working pressure of the plastic shell breaker outer pressure membrane assembly should not exceed 0.2 MPa.
Internal and external pressure ultrafiltration membranes cannot be used in opposite applications. Due to the relatively large diameter of internal pressure ultrafiltration membranes, if they are used as external pressure membranes, they can be squeezed to facilitate fracture of the bond, resulting in damage. Therefore, in order to ensure the proper functioning of all ultrafiltration equipment, internal and external membranes are not suitable for opposite applications.