From the beginning of the 20th Century, and especially during the Fifties, the FILTER PRESS experienced a big development that has led to a very reliable and mature technology and a high level of automation in our days.
The FILTER PRESS is one of the best options when you wish to obtain:
- High level of separation with a very good catching of solids.
- High contents of solids in the cake.
- Good possibilities of elimination of soluble compounds.
- Simple and reliable operation.
- Long lifetime equipment.
BASIC ELEMENTS
It is the structural support of the filter. It is composed by the following elements:
Closing device
The closing device operates electro hydraulically with a hydraulic double acting pump that acts one or more double action cylinders.
Drive head
It hosts the closing device and constitutes one of the sides of the filter press.
It is normally made in cast iron or electro-welded ply.
When in cast iron, it normally includes the closing cylinder.
It is supported by legs linked to the bearings of the filter either rigidly or sliding.Head piece
It constitutes the other side of the filter press and it is equipped with the pipe connections to the filter.
Made in cast iron or electro-welded ply, supported by legs, with roller to allow the coupling to the filter package.End piece
It transmits the closing force to the filtering package. It may host the rest of the external connections of the filter pipes.
Made in cast iron or ply.
It slides over the side bars or guide beam trough sliding guides or by means of a wheel with leveling elements.Side bars or guide beam
It is the connection element between the head piece and end piece of the filter, to which the side bars are linked. They are the support to the filter package.
The process of separation liquid-solid takes place on the elements of the filter package. It is formed by the following elements:
Filter plates
They make the filter chambers where the cake is formed and held.
The chamber may have a fixed thickness, or may be subject to vary its thickness during the process. This gives rise to a basic classification in filter press: chamber filter or membrane filter.
In CHAMBER FILTERS, the chamber is formed by flat plate and frame, or most commonly, by a recess in the plate itself.
The manufacturing material of the plate has evolved from wood, steel and cast iron to plastic materials, being polypropylene the most commonly used material nowadays.
For special applications other materials may be used.Filter clothes
They carry out the first separation, and this leads into the formation of the precoat on which the filtration process carries on, determining the initial cut-off level of the filtration.
Sometimes in high pressure filtration, support clothes are used to ease the filtrate evacuation and improve the filtration cloth life.
The high requirement of manpower has been one of the traditional disadvantages of the filter press against other similar equipments.
In order to compensate this inconvenience, there has been developed some auxiliary equipment that contributes to the automation of its operation, reducing the need of manpower to the surveillance of the cake discharge operation.
Plate shifting device
They make the opening and the shifting of every plate for the cake discharge.
It is composed by a double clamp system over roller chain that holds every plate from both sides at their fulcrum point level.
The drive is made by hydraulic motor with adjustable speed and torque, by the back and forth movement of the clamps, picking up the plate and moving it to the shifted end piece.Cloth cleaning device
One of the most common maintenance problems in the filter is the clogging of the clothes.
This causes a serious decrease of production and may lead to dysfunctions in the filter.
In order to keep the cloths in good working conditions, they must be washed frequently by chemical washing and/or pressure water washing.
The automatic cleaning device has been developed to accomplish this function.
Our equipment synchronizes the operation of the plate shifting device and the cloth cleaning device that works with high pressure water supplied by the appropriate pumps.Collection trays
Their mission is to avoid the dripping of the filter to interfere in the rest of the auxiliary installations. They collect the water in the cloth washing process.
The system is formed by two lowering trays that close below the filter with a proper tilt, and open over the cake discharge hopper.
Their drive is hydraulic and they operate automatically by means of a double-acting piston, camshaft and eccentric, it is accomplished from the hydraulic unit.
They are made in different materials depending on the corrosion ambient and filtrate conditions.Cloth suspension system
The filters are automatic in most of their operations.
Only the discharge operation may present some problems.
The clothes suspension system is designed to solve this problem.
This equipment changes de design of the clothes, that are suspended by a flexible and mobile support mechanism that fits the plate shifting device.
By this mechanism, the cloths are left hanging at the discharge hollow, expelling the cake and easing its discharge.Electric control
A good control is basic to ensure the good performance of the filter press and its accessories.
Due to the high reliability of the new electronic systems, the control is performed in most of cases by PLC elements, requiring the confirmation of every order previous to the next execution.
TYPES OF FILTER PRESS
The chamber filter is the most extended type because of its simplicity and exceptional performance.
It operates with a chamber of fixed thickness that will depend on the inlet suspension conditions and the characteristics of the mud to filtrate, especially the solids concentration.
They are made in a wide range of sizes, volume and cake thickness, and they incorporate different accessories for the automation of all their operations.
They can be side bars version or guide beam version.
The membrane filter represents a big advance compared to the conventional chamber filter.
It allows the modification of the chamber thickness by the inflation of the membranes, and so this process is not only based on the pressure filtration that overcomes the loss of load, but on the cake compression.
This system allows the following advantages:
- The handling of products that a chamber filter cannot handle.
- Better accommodation to different inlet conditions, and more regular outlet conditions.
- There is therefore no need to condition the mud to the filtration aids.
- Higher production/m2 due to the normal reduction of the operation cycle, which means less space and less auxiliary equipment required.
- Reduction of the cake moisture, with the consequence of less transport and disposal expenses, and an important saving of energy in the drying process.
- The use of conventional pumps, with no need of high pressure piston diaphragm hose pumps.
- More uniformity in the cake characteristics, with benefits on the disposal and the recovery of landfills.
In the washing and blowing processes, when required, these operations take less time and obtain better results, and allow a reduction in the consumption of water and blowing air because the cake is more uniform and avoids the preferred ways.
Nowadays, the membrane plates are manufactured with detachable and re replaceable parts, in different materials, especially in natural or synthetic rubber.
