The globe valve is used to cut off the flow of the medium. The globe valve is suitable for frequently opened occasions. The sealing parts of the globe valve are the disc and the valve seat. In order to make the globe valve close tightly, the mating surface of the disc and the valve seat should be grinding or using gaskets. The sealing surface can also be inset with bronze, stainless steel and other corrosion-resistant and wear-resistant materials. The disc and stem of the globe valve are connected with each other, so that the disc and stem are closely fitted. The lifting of the disc of the globe valve is generally controlled by the stem. The upper part of the stem of the globe valve is the handwheel, and the middle part is the thread and packing sealing section. The role of the packing is to prevent the internal medium of the valve body from leaking along the stem. Globe Valve,Globe Control Valve,Globe Valve Types,Flanged Globe Valve WUXI KVC-VALVE , https://www.wxkaiweixi.com
In membrane separation processes, solutes are carried to the membrane surface by the permeate flow. When the solute cannot pass through the membrane completely, it accumulates on the surface due to the membrane's retention ability. This accumulation leads to a higher concentration near the membrane surface, a phenomenon known as concentration polarization.
As the concentration at the membrane surface increases, it raises the osmotic pressure across the membrane. This, in turn, reduces the effective pressure driving the permeate flow, which ultimately lowers the membrane's flux. If the local concentration exceeds the solubility limit of the solute, precipitation can occur, forming a gel-like layer on the membrane surface.
In addition, when processing liquids containing suspended particles, cells, or other solid components, a similar gel layer may form on the membrane surface. This specific type of polarization is referred to as gel polarization. Both concentration and gel polarizations can significantly affect the efficiency and performance of membrane systems over time.
Proper operation, regular cleaning, and optimized design are essential to minimize these effects and maintain high separation efficiency.
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Concentration polarization concept in membrane separation
Understanding Concentration Polarization in Membrane Separation