Selection of filter media for filter press bai 1. Overv […]
Selection of filter media for filter press bai
1. Overview The filter medium is the heart of the filter press. Whether the filter medium matches the filter mechanism of the filter press and the suspension, dao directly affects the normal use and working efficiency of the filter press. Therefore, the selection of suitable filter media is the core of filter press technology. Although various filter media manufacturers provide a lot of technical information on the performance and selection methods of the filter media produced, the choice of filter media used in the filter press still depends on the accumulation of long-term experience in the material filtration process and filtration experiments to determine. For this reason, Jingjin Group has established an international advanced level of filtration and separation laboratory. While serving hundreds of thousands of customers around the world, it has accumulated rich experience and a large amount of experimental data in the selection of filter media, which can be used for solid-liquid separation. Users provide comprehensive selection services. 2. Filter media suitable for plate and frame filter press The filter medium used for plate and frame filter presses is generally filter cloth, and some use cardboard or filter paper (cotton cake filter and plate and frame oil filter) as the filter medium. Filter cloths suitable for filter presses are classified by material, with synthetic fibers being the most; by structure, they are mainly woven fabrics, fiber felt, cardboard, and filter paper. Various literatures on fabrics and non-woven filter cloths have a large number of introductions, and each manufacturer has detailed instructions on filter cloths.
When the unshaped filter cloth is filtered, solid particles (fine particles) are easily trapped in the bell mouth to block the filter channel, and cannot form a good bridging pore, which affects the filtering effect. The filter cake and filter cloth stick. Affect the shedding of filter cake and the water washing regeneration of filter cloth. After high temperature setting, the filter cloth has a smooth surface, stable pore structure, and is not easy to deform; the bell mouth forms a funnel shape, solid particles will not be blocked; it can form a good bridging filter layer; the filtration accuracy is higher, and the filter cake falls off It is easy to clean and regenerate the filter cloth. It improves the sealing between the filter plates, reduces the capillary leakage between the filter plates, and is more suitable for the operation of the automatic filter press. The surface high temperature shaping technology has the best treatment effect. Only the monofilament filter cloth can keep the processed structure stable and not deformed, but the impact resistance and tensile strength of the monofilament filter cloth are far lower than that of the multifilament filter cloth, and it is very easy to break. Therefore, filter cloth manufacturers have produced a single-multifilament filter cloth to overcome the weakness of monofilament filter cloth. Use monofilament filter cloth as the retention layer and multifilament filter cloth as the support layer. The filter cloth produced by this processing technology is very suitable for the use requirements of filter cloth for filter press.
Three, the selection principle and method of the filter cloth of the plate and frame filter press
(1) Choose the material of the filter cloth according to the chemical and physical properties of the material. All filter cloth suppliers provide detailed technical information as much as possible, which can be selected by reference.
(2) Select the permeability (maximum particle size) of the filter cloth according to the requirements of filtration accuracy. The preliminary selection can be made with reference to the technical parameters such as the maximum particle size provided by the filter cloth supplier. Although the filter cloth plays an important role in the initial filtration accuracy of the filter press, the initial filtration accuracy is not as high as possible. It is only necessary to consider that the filtration accuracy can meet the minimum requirements. After the filter press forms a filter layer after filtering for a period of time, the retention effect of the filter cloth is very small. The "filter layer" that really plays the role of fine filtration is the key to the use of filter press technology.
(3) The peeling performance of the filter cake. When choosing filter cloth, pay special attention to the peeling performance of filter cake. The surface of the filter cloth is smooth and flat, the filter cake peels off quickly, and the operation time for thorough filtration is short, and the efficiency is high. The filter cake adheres to the filter cloth and is not easy to peel off, which will extend the operating time of the filter press and reduce the work efficiency. To replace the filter cloth, it will take longer. Nowadays, it is more troublesome to replace the filter cloth of the widely used chamber filter press. Selecting monofilament filter cloth has better cake unloading performance than long multifilament and short fiber filter cloth, and selecting satin weave has better cake unloading performance than plain weave filter cloth.
(4) The regeneration performance of the filter cloth. When choosing filter cloth, pay attention to choosing filter cloth with good regeneration performance. The filter cloth with good regeneration performance can be washed directly on the filter press to reduce the number of cloth changes. The filter efficiency of the replaced filter cloth is restored to more than 80% after simple treatment (drying, washing, etc.).
(5) Filtration experiment of materials. The use technology of the filter press is an experimental technology. After the initial selection of filter cloth, it is very important to carry out filtration experiments on the raw materials (without changing the properties and process conditions of the materials). Carry out a sample experiment on material filtration. Inspect the filter cloth's filtration rate, retention effect, filter cake moisture content, cake unloading performance, regeneration performance, etc.