Environmental protection is an important principle that every factory needs to practice. In the daily operation of factories and mines, a lot of sewage and wastewater will inevitably be generated. If they are not effectively treated but are directly discharged into the environment, it will aggravate the environment and water quality. At the same time, it also adversely affects the nearby residents, making it difficult to drink water and live normally. The emergence of the filter press can solve this problem very well. The waste in the sewage is separated from the water, and the water can be directly recycled, so as to achieve the purpose of green and environmental protection. If you need to buy filter press equipment, what problems should you pay attention to when purchasing the filter press you need? How can I buy the right filter press equipment?
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When purchasing filter press equipment, we need to know the purpose and object we want to choose. In addition to knowing that the filter press is a filtration device that can separate solids and liquids, we also need to know the working principle of the filter press. We should try to choose a filter press device with a relatively low water content in the filter cake after filtration, and also choose a filter press. For the filter press equipment with relatively high precision, the filter press equipment suitable for the filtrate should be selected according to the basic properties of the filtrate. For example, if you want to choose a filter press with low moisture content in the filter cake, then you can consider a diaphragm filter press. If you want to choose a filter press with high filtration accuracy, you can choose a plate and frame filter press.
After determining the type of filter press, we have to patiently check the quality of the equipment. For filter press equipment, the decisive issue affecting its quality is the quality of the filter plate. Therefore, when you buy a filter press, you must carefully check the quality of the filter plate to see if the filter plate is finely made on the surface, and whether there are any defects or hollows; secondly, the material should be environmentally friendly and tasteless, and the surface should be moist. It is a good filter plate to appear to have a certain degree of softness. In order to reduce costs, some filter press manufacturers now use cast filter plates made of discarded filter plates, which have great quality problems.
The above is the relevant content on how to choose a filter press, I hope to help you. If you are interested in filter presses, please come to inquire, we are a professional filter press supplier with professional technology and the quality of the filter presses provided is guaranteed.
In many industrial processes that feature the handling of liquids, the substances being transferred may occur in an aqueous or "muddy" state with the liquid portion needing to be removed. This liquid-removal stage may take place during the production process &#; for example, in the filtration of edible oils or yeast solutions &#; but it more frequently occurs at the end of a process such as wastewater treatment when the waste sludge that has formed must be withdrawn.
Since the disposal of such sludge is calculated based on weight and volume, its thickening and drying is particularly lucrative for the processor. During the thickening and drying process, the sludge is treated using chemicals and/or physical processes so that the waste sludge forms into flake-like solids. After adjusting the pH level to neutral or alkaline via the use of milk of lime, the subsequent dewatering process separates the water for disposal, and the remaining volume of sludge is significantly reduced.
The simplest technology for this process involves the collection and thickening of the sludge through the use of gravity. However, it is significantly more effective to use technical drying methods via processes such as centrifuges and evaporators or, more commonly, chamber filter presses (see Figure 1).
The operational principle of the chamber filter press relies on the use of plastic frames pressed together under high pressure. Inside the frames are hollow chambers (from which the press gets its name) surrounded by filter cloth. When the sludge is fed into the chambers using pressure, a "filter cake" forms inside the chambers and the filtrate flows through the filter cloths into drainage channels.
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When all the chambers are completely filled, the sludge feed stops. The press is then opened and the solid filter cakes can be removed. After closing, the press is ready for a new pressing process.
To fill these presses, filter material and pressure are required. The pressure &#; usually between 8 and 15 Bar (116 and 218 psig) at its peak &#; should be even so the sludge flocs are not destroyed during feeding. The flocs should also have enough free space in the feed area. In addition to the constantly increasing counterpressure that occurs until the end of the pressing, a further constraint is that an empty-running sludge tank can lead to dry-running of the pump used to generate pressure.
To build pressure, different systems of displacement pumps are frequently used, including piston diaphragm pumps, applied most often for large presses. In these large and costly units, one or two diaphragms are hydraulically actuated and feed the sludge into the press through a series of valves. These pumps may require an air-pressure vessel to equalize the feed rate and a maximum pressure monitor or bypass, resulting in large overhead costs even for small plants. Eccentric screw pumps are also used, either as self-regulating pumps (with motors that are electronically controlled via a frequency converter) or as cyclical systems (where an air-pressure vessel is "charged" by the pump). This valve-free procedure is advantageous when processing large sludge quantities and when long fibers prevent the use of valves. However, operational constraints need to be considered in small and medium-sized plants due to their sensitivity to abrasion and dry-running. The space required to use this system is also considerable.
The list of filter press pumps also includes hose diaphragm piston pumps, which function similarly to piston diaphragm pumps but with crimped hoses rather than diaphragms. Piston pumps typically generate strong pulsation and require constant lubrication. Both of these pumps are characterized by their simple electrical operation and fairly high installation and maintenance costs.
By comparison, it is easier to use air-operated double-diaphragm (AODD) pumps; they are resistant to dry-running, virtually maintenance-free, self-priming, self-regulating and highly compact. Without the need of an operator or electronic system, the counterpressure of the chamber filter press regulates the feed rate automatically. The feed rate decreases continuously as counterpressure increases simultaneously to the degree of filling. This effect can be used to detect when the chamber filter press is full. When this point is reached, the pump virtually stops &#; zero feed rate &#; or only occasionally makes a delivery stroke. In addition, the use of compressed air as drive power to move the diaphragms results in a highly efficient, regular and gentle cyclic drive that allows the medium to be fed smoothly.
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A standard AODD pump is typically limited to the pressure of the supplied air, which may be insufficient to fill the press. For this reason, it is often necessary to increase the pressure, for which there are three different technical solutions, outlined here.
The first variant uses one of the diaphragms on a standard pump to generate additional pressure. The force of this diaphragm, which is surrounded only by air and compressed air, is transferred to the feed diaphragm via the internal diaphragm connection, enabling the feed diaphragm to work with double the pressure. This method is rarely used anymore because it leads to high pulsation, low feed rates and high air requirements. It also commands high service costs because the diaphragm on the air side is sensitive and breaks quickly.
&#;When selecting a filter press pump, AODD pumps offer several advantages.&#;
Another variant is to operate a standard pump with an air-pressure amplifier, which drives the pump with increased air pressure. This process is limited by the fact that a standard pump is often used. Although these pumps are equipped with external reinforcements, from a technical perspective the standard pumps are designed and built for significantly lower pressures and, as a result, have limited resistance to the increased strain. Also, the increased pressure resulting from these air-pressure amplifiers, or "boosters," pulsates strongly, which can influence the flow of the product. Boosters also may reach their limits in maintaining pressure, e.g., during repressing, because the devices used are almost always too small. These devices yield the required end pressure but may require a longer filling time.