Working principle of candle filter

Working principle of candle filter:

The candle filter is an automated pressure filter device with one or more filter elements in the cylinder. The filter element is covered with a special filter cloth selected according to the characteristics of the raw material liquid (some special raw material liquids need to add filter aids, such as activated carbon, diatomaceous earth, etc.)1. Its working process is divided into two stages: filtration and backwashing and slag removal:

 

Filtration stage: When the liquid is pumped into the filter, the liquid phase will pass through the filter medium (filter cake layer formed by filter cloth and possible pre-coated filter aids) into the center of the porous filter element, and then be collected and discharged at the clear liquid outlet. Before the filter cake layer is formed, the discharged "clear liquid" may return to the raw material slurry inlet and be sent to the filter for circulation filtration until the filter cake layer is formed and can meet the filtration requirements. At this time, the clear liquid is no longer circulated, but is sent to the next process through the three-way valve for use. As the filtration proceeds, solid matter continues to accumulate on the surface of the filter cloth. When these solid matter reaches a certain thickness, a "filter cake layer" is formed1. Back-blowing and slag removal stage: After a period of normal filtration, when the filter cake layer reaches a certain thickness, the rate at which the filtrate passes through the filter cake layer decreases, and the filtration efficiency becomes worse. At this time, the system will back-blowing and cake removal operations according to the signal provided by the pressure sensor. Back-blowing gas (such as compressed air, nitrogen or saturated steam) flows from the non-porous central tube to the porous tube, causing the filter cloth to swell and round, effectively vibrating and peeling off the filter cake, while removing the particles in the filter cloth fibers, improving the back-blowing efficiency, and quickly restoring the filter cloth's filtration capacity. After that, open the valve at the bottom of the cylinder to discharge the slag, close the slag discharge port after the slag discharge is completed, return to the initial state before filtration, and prepare for the next round of filtration.

 

Advantages of candle filters:

Good filtration effect:

High-precision filtration: It can directly perform fine filtration, with a maximum precision of 0.2μm, and has a significant filtration effect on tiny particles, which can meet the production requirements for high filtrate purity.

 

Filter cake layer filtration: The gaps between the particles in the filter cake layer are very small, which can effectively prevent the escape of particulate impurities in the liquid, making the filtrate clear and achieving good filtration effect. And by pre-coating the filter aid to form a filter cake layer, the filtration accuracy and clarity can be further improved.

Wide range of applications: Suitable for a variety of special filtration occasions such as high impurity content, high precision requirements, high viscosity, high temperature, strong acid and alkali. Whether it is corrosive liquids in the chemical industry, viscous materials in the food industry, or high-temperature production processes, candle filters can operate stably.

Strong filter cake processing capacity:

Large filter cake recovery: With a large filtration area and excellent filter cake peeling performance, a large amount of high-value filter cake can be recovered from high-solid content liquids at one time, which improves the product recovery rate and production efficiency.

Filter cake can be washed and dried: The intercepted filter cake can be washed multiple times directly in the filter, and after adding the drying design, the filtration, washing, drying and unloading operations can be integrated, reducing investment, shortening the process flow, and saving energy consumption.

High degree of automation: The entire filtration process can be fully automated. Through computer control systems, pressure sensors and other equipment, it can automatically complete filtration, backwashing, slag discharge, cleaning and other operations, reducing the workload and errors of manual operations, and improving production efficiency and stability.

Energy saving and environmental protection:

The filter medium can be reused: The filter medium (such as filter cloth, filter aid, etc.) can be reused many times after proper treatment, which saves a lot of filter consumables and reduces production costs.

Low energy consumption: The main body is a static component, and the dynamic backwash design makes the equipment have low energy consumption and relatively low operating costs. In addition, during the filtration process, the liquid is transported and filtered in a closed environment, which reduces the volatilization and leakage of the liquid and reduces the pollution to the environment.

Easy maintenance: The equipment structure is relatively simple, mainly composed of a cylinder, a filter element, a filter cloth, a control system, etc., which is easy to disassemble and install. And the filter element has a long service life and low maintenance cost.

Good airtightness: The cylinder is firmly sealed, ensuring that there is no leakage in the production process. It is suitable for filtering highly corrosive, volatile or dangerous liquids, and improves the safety of production.

Candle filters are mainly used in the following fields:

 

Food industry:

Liquid beverage filtration: used for clarifying and filtering alcoholic beverages (such as wine, beer, liquor, etc.), juices, beverages (tea beverages, milk beverages, etc.), removing impurities, microorganisms, sediments, etc., and improving the transparency and taste of beverages. For example, in the winemaking process, candle filters can effectively remove yeast, protein and other impurities in the wine, making the wine clearer and more stable.

Sugar solution filtration: activated carbon decolorization filtration and precision filtration of sugar solutions such as sugar and glucose to remove pigments, impurities, etc. in the sugar solution and improve the purity and quality of sugar.

Condiment filtration: Filtration of condiments such as soy sauce, vinegar, and chili sauce to remove turbidity, sediments, microorganisms, etc., making the condiments clearer and more hygienic.

Pharmaceutical industry:

Biopharmaceutical filtration: In the biopharmaceutical process, it is used for fermentation broth filtration, crystal filtration, mother liquor or suspension filtration, etc., to remove cell debris, protein, nucleic acid and other impurities in the fermentation broth, and to separate and purify drug crystals.

Filtration of Chinese medicine extracts: Chinese medicine extracts often contain a large amount of impurities, sediments, etc. Candle filters can effectively remove these impurities, improve the purity and quality of Chinese medicine extracts, and provide high-quality raw materials for subsequent preparation production.

Catalyst filtration and recovery: The catalysts used in the pharmaceutical process need to be filtered and recovered. Candle filters can efficiently separate catalysts and reaction liquids to achieve catalyst recovery and reuse.

Chemical industry:

Petrochemical industry: used for filtration in the mining, processing and refining of oil and natural gas, such as dehydration, desalination, sand removal of crude oil, etc., as well as filtration, separation and purification of petrochemical products.

Fine chemicals: In fine chemical production, it is used for filtration of various chemical raw materials, intermediates, and products, such as filtration and recovery of pesticide intermediates, filtration of polyether desalination, filtration of high-purity alumina, etc.

Chemical wastewater treatment: A large amount of wastewater is generated during the chemical production process. Candle filters can be used for pretreatment and deep treatment of wastewater to remove suspended matter, organic matter, heavy metals and other pollutants in wastewater.

Water treatment industry:

Industrial wastewater treatment: Applicable to the filtration of various types of industrial wastewater, such as heavy metal wastewater (electroplating wastewater, circuit board production wastewater, hot-dip galvanizing wastewater, etc.), battery wastewater, magnetic material wastewater, electrophoresis wastewater, etc., to remove heavy metal ions, suspended matter, organic matter and other pollutants in the wastewater to meet environmental emission standards.

Drinking water treatment: It can be used for deep treatment of drinking water, remove microorganisms, organic matter, heavy metals and other pollutants in the water, and improve the quality and safety of drinking water.

Recycled water reuse: In the recycled water reuse system, it is used to filter suspended matter, organic matter and other impurities in the recycled water, so that the recycled water meets the reuse standards and realizes the recycling of water resources.

Oil and oil ink industry:

Oil refining: Used for dewaxing, decolorization and fine filtration of vegetable oil and edible oil, remove wax, pigment, impurities, etc. in the oil, and improve the purity and quality of the oil.

Ink filtration: Used in the production process of ink, filter pigment particles, impurities, etc. in the ink, and improve the fineness and quality of the ink.

Other fields:

Ceramic industry: used for filtering ceramic slurry, removing impurities and particles in the slurry, and improving the quality and performance of ceramic products.

Mineral processing: used for ore dressing, dehydration, concentration, etc., as well as tailings treatment and recovery during mineral processing.

Electronic industry: used for filtering liquid for electronic and optical lens grinding, removing particulate impurities, metal ions, etc. in the grinding liquid, and ensuring the purity and quality of the grinding liquid.

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