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The chamber filter press includes multiple plastic filter frames, which are squeezed together under high pressure. Inside these filter frames is a hollow filter chamber, hence the name of the filter press. The filter chamber is surrounded by filter cloth. When pressure is applied to make the sludge enter the filter chamber, a “filter cake” can be formed in the filter chamber, and the filtrate flows into the drainage channel through the filter cloth. When all the filter chambers are completely filled, the sludge feeding is stopped. Now you can turn on the filter press and take out the solid filter cake. After closing the filter press, you can prepare for a new filter press process.
Positive displacement pump
To build pressure, various forms of positive displacement pumps are often used, including piston diaphragm pumps, which are most commonly used in large filter presses. In these large and expensive devices, one or two diaphragms are hydraulically driven and the sludge is sent to the filter press through a valve. Even if some small equipment is used, these pumps will also incur high overhead costs, such as air pressure vessels, maximum pressure monitors or branch pipes used to balance the feed rate. Eccentric screw pumps are also used, which can be used as self-regulating pumps (with a motor electronically controlled by a frequency converter) or as a circulation system (when the air pressure vessel is filled with gas by the pump).
When a large amount of sludge is processed or the valve cannot be used due to the presence of long fibers in the sludge, this treatment process without a valve is particularly useful. However, its application in small and medium-sized equipment is restricted because they are quite sensitive to wear and dry running. The space required to use the system is also considerable.
Other types of positive displacement pumps also include hose diaphragm piston pumps and piston pumps. The function of the former is similar to that of piston diaphragm pumps, but the inside is a corrugated hose instead of a diaphragm. The latter piston pump usually produces strong pulsation and requires continuous lubrication. Both of these pumps have the following characteristics-simple electrified operation, installation and maintenance costs are quite high.
In contrast, pneumatic double diaphragm (AODD) pumps are easier to use; they are resistant to dry operation, almost maintenance-free, self-priming, self-adjusting, and extremely compact.
When there is no operator or electronic system control or intervention, the back pressure of the chamber filter press automatically adjusts the feed rate. When the back pressure increases simultaneously with the filling degree of the filter chamber, the feed rate continues to decrease. This effect can be used to detect when the chamber filter press is full.
When the full state is reached, the pump actually stops working—the feed rate is zero—or it only makes the delivery stroke occasionally. Compressed air can also be used as a driving force to move the diaphragm, with high work efficiency, and a regular and gentle cyclic drive can be formed, so that the medium can be fed smoothly.