Overview
The plate and frame filter press is a classic and widely used solid-liquid separation equipment, which plays a vital role in the production processes of numerous industries. It mainly relies on the plate and frame structure and the applied pressure to effectively separate the suspension containing solid particles, thus obtaining relatively clear filtrate and relatively dry filter cake. It is commonly found in industries such as chemical engineering, pharmaceuticals, food, mining, and environmental protection, making significant contributions to improving product quality and reducing environmental pollution.
Working Principle
Loading Process:
Firstly, the suspension that needs to be subjected to solid-liquid separation is transported to the inlet of the plate and frame filter press through the feed pump and then flows into each filter chamber. The filter chamber is composed of alternately arranged filter plates and frames. Filter cloth is sandwiched between adjacent filter plates and frames, forming an independent filtering space.
Under the action of pressure, the suspension is evenly distributed in each filter chamber, preparing for the subsequent filtering process.
Filtration Stage:
After the suspension enters the filter chamber, under the continuous pressure provided by the feed pump and the squeezing effect of the plate and frame itself, the liquid part passes through the pores of the filter cloth and flows out along the filtrate channels on the filter plates, converges and is discharged through the filtrate outlet, while the solid particles are retained on the surface of the filter cloth and gradually accumulate in the filter chamber to form a filter cake.
As the filtration continues, the filter cake keeps getting thicker and the filtration resistance will increase accordingly. However, under the action of pressure, the filtrate can still continue to seep out until a certain degree of filtration is reached or the set filtration time expires.
Discharging Process:
When the filtration is completed, first close the feed valve to stop the feeding, and then loosen the tightening device between the filter plates and frames to open the filter plates and frames one by one.
At this time, the filter cake attached to the filter cloth will fall off naturally or be discharged with the assistance of manual operation (such as using a scraper tool). The filter cake is cleaned off the filter cloth and collected, completing the whole solid-liquid separation process. After that, the plate and frame can be assembled again to prepare for the next round of filtration operation.
Performance Characteristics
High Efficiency in Solid-Liquid Separation:
It can achieve good separation effects for suspensions of various concentrations and particle sizes. Especially for materials containing finer particles and with higher viscosity, it can still obtain relatively clear filtrate and filter cake with a low moisture content. The separation efficiency is high and can meet the production process requirements of different industries.
For example, in the chemical industry, when separating some mixed liquids after reactions, or in the mining industry when dewatering tailing slurry, it can play an excellent separation role.
High Operational Flexibility:
The number of filter plates and frames can be flexibly adjusted according to the actual production needs to change the filtering area so as to adapt to materials with different processing volumes. Meanwhile, parameters such as filtration pressure and filtration time can also be reasonably set according to the characteristics of materials and separation requirements, which is convenient to operate and easy to control.
For example, in food processing, for the filtering needs of different batches and production volumes of raw materials, efficient filtration can be achieved through simple adjustments.
Simple Structure and High Reliability:
The overall structure mainly consists of filter plates, frames, filter cloths, corresponding tightening devices, and inlet and outlet pipelines. The structure is relatively simple and intuitive, easy to understand and maintain. Moreover, each component has been verified through long-term practice and has high reliability and stability with a long service life, and can operate stably in relatively harsh industrial environments.
In the production workshop of pharmaceutical enterprises, even if it runs continuously for a long time, it can ensure the stable and reliable completion of solid-liquid separation work and ensure the smooth progress of the drug production process.
Wide Applicability:
Due to its strong adaptability to materials, it can handle almost all kinds of solid-containing suspensions generated in various industries. Whether it is acidic, alkaline or materials containing special properties such as organic solvents, it can carry out effective solid-liquid separation operations without being overly restricted by the chemical properties of materials.
It is widely used in many aspects such as sewage sludge treatment in the environmental protection field and separation and purification of intermediates in the chemical industry.
Structural Components
Filter Plates:
They are one of the key components of the plate and frame filter press. Usually made of high-strength materials such as polypropylene, cast iron, or stainless steel, they have sufficient strength and rigidity to withstand the pressure during the filtration process.
The surface of the filter plate is designed with channels for the filtrate to flow out and a structure for sealing cooperation with adjacent filter frames to ensure that the filtrate can be discharged smoothly and there will be no leakage between filter chambers.
Filter Frames:
Used in conjunction with filter plates, they are also mostly made of solid materials. Their main function is to form a space for accommodating the filter cake between the filter plates, determine the size and volume of the filter chamber, and provide a place for the accumulation of the filter cake.
The periphery of the filter frame has a sealing structure. When it is in contact with the filter plate, it can ensure good sealing performance to prevent the suspension from leaking to the outside or flowing between filter chambers.
Filter Cloths:
As the medium that directly contacts the suspension and realizes filtration, they have various materials. Common materials include cotton, polyester fiber, and polypropylene, which are selected according to different material characteristics and filtering requirements.
The filter cloth has an appropriate pore size, which can effectively intercept solid particles while allowing the liquid to pass through smoothly. Moreover, its installation and replacement are relatively convenient, facilitating timely maintenance according to the wear situation during the use process.
Tightening Devices:
They are mainly used to tightly press the filter plates and frames together to form sealed filter chambers and ensure that the filtration process is carried out under a certain pressure environment. Common tightening methods include manual screw tightening and hydraulic tightening, which can be selected according to actual needs and the scale of the equipment.
The reliability of the tightening device is crucial for the normal operation of the entire filter press, directly affecting the filtering effect and the sealing performance of the equipment.
Inlet and Outlet Pipelines:
The inlet pipeline is responsible for transporting the suspension to be filtered into each filter chamber inside the plate and frame filter press. The diameter size and connection mode of the inlet pipeline should be reasonably designed according to the feed flow rate and equipment layout.
The outlet pipelines include the filtrate outlet pipeline and the filter cake discharge channel. The filtrate outlet pipeline should ensure that the filtrate can be discharged and collected smoothly, and the filter cake discharge channel should facilitate the smooth detachment of the filter cake from the equipment during the discharging stage.
Application Cases
Chemical Industry:
In the production process of aluminum sulfate, there will be mother liquor containing a large amount of calcium sulfate and other impurities. Through the plate and frame filter press for solid-liquid separation, calcium sulfate solids can be effectively filtered out to obtain clear filtrate, realizing the recycling of raw materials, improving the purity of products, and reducing subsequent treatment costs.
For some mixed liquids after organic synthesis reactions, the plate and frame filter press can be used to separate out impurities such as catalysts and unreacted solid raw materials, providing a pure material basis for the subsequent product refining steps.
Pharmaceutical Industry:
In the production of antibiotics, the fermentation broth needs to be subjected to solid-liquid separation. The plate and frame filter press can efficiently separate solid impurities such as mycelium under the premise of ensuring that the active ingredients of the drug are not damaged, obtaining filtrate containing active ingredients and preparing for subsequent extraction, purification and other process steps to ensure the quality and efficacy of drugs.
Before the traditional Chinese medicine extract is made into the final pharmaceutical product, it often needs to be filtered through the plate and frame filter press to remove solid particles such as drug residues, making the extract clearer and meeting the quality standards of drug production.
Mining Industry:
In the concentrator, when dewatering the flotation slurry, the plate and frame filter press can remove a large amount of water from the slurry to obtain a filter cake with a low moisture content, which is convenient for subsequent transportation and further processing. At the same time, it can reduce the occupied area of the tailings pond and the potential pollution to the environment, and improve the comprehensive utilization efficiency of mineral resources.
For the leaching solution of some precious metal ores, through the plate and frame filter press for solid-liquid separation, valuable metals can be recovered to realize the effective recycling and utilization of resources and increase the economic benefits of enterprises.
In conclusion, the plate and frame filter press plays an indispensable role in the production and environmental protection treatment processes of many industries by virtue of its unique working principle, excellent performance characteristics and wide applicability. It is an important equipment for realizing solid-liquid separation, improving resource utilization efficiency and ensuring product quality. With the continuous progress of technology, its functions and application fields are also expected to continue to expand and be optimized.
