- Advantages of the is replaced by squeezing with the underneath Membrane Filter Plate Technology The dewatering of solids can be done with various techniques, such as centrifuges, belt filter presses, chamber filter presses and also membrane chamber filter presses.
- The final selection of a filtration method is determined by the requirement for quality and degree of dryness of the filtered cake. Prior to some years ago the results achieved on a standard recessed chamber filter press were quite acceptable until the membrane filtration technique created better cake quailty with higher solids dryness.
- The two techniques-conventional chamber filtration membrane filtration differ only in one important point: The final dewatered cake is a by the result of squeezing by the membrane . In a conventional chamber filter press, the cake is built up in layers until the chamber is completely filled with solids.
- The more cake being built up, the less it becomes permeable and the flow rate decreases measurably. Intense compressible products reduce the cake permeability causing long filtration cycles and the increase of costs. the entire membrane.
- This shortens the membrane and achieves an even movement of the The significant advantage of the filtration phase is conducted in only the efficient area. The unproductive phase of the pressure filtration, where the flow rates are already greatly reduced filtration cycle considerably.
- During squeezing the porosity of membrane. the filter cake decreases notably, so that additional dewatering occurs. With conventional pressure filtration the cake next to the cloth is drier than in the center due to uneven distribution of pressures in the filter cake.
- The membrane causes a more. even spread of the pressure so that a homogeneous porosity is created within the cake. The average grade of dewatering is profoundly higher with the membrane filtration technique compared to the conventional dewatering technique with chamber filler plates.
- Due to shorter cycles or increasing solid action-cake cake content of up to 50% the filtration efficiency almost doubles. In addition the homogeneous p porosity achieves the best cake washing results. Center core The center core meets all mechanical requirements of the Membrane Plate.
- The engineered design of the center core in conjunction with a new modified polypropylene material, provides excellent support of the membrane during the filtration cycle. The body (center core) of the membrane plate is profiled (pipped) so that the membrane is not in contact with the body. At the beginning of the squeezing cycle the squeeze medium is distributed Special modified pips on the body reduce the temperature transfer and create channels which can be used to cool or heat the membrane plate, so the Membrane Plates can be used at temperatures from -10° C up- to 90° C Membrane Basically the membrane movement causes bending stresses, which can adversely affect the membrane’s ability to resist chemical attack.
- To counteract this the Membrane Plate has no but a flexible area , which diminishes the surface tension, Due to the flexible area the membrane. can be constructed thicker than usual and therefore offers both greater physical strength and resistance chemical attack.
- The well-rounded contour of the membrane, with no stay bosses or center feed hole in the. filtration area allow the unhindered movement of the membrane. Corner Feed In addition to the many advantages of eliminating stay bosses or a center feed hole, our corner feed design helps to eliminate the possibility of variations in the chamber space between the membrane faces, which can result from deformation of the center core by out-of-balance forces, those problem cases the Addition-ally, the corner feed design allows for a more evenly distributed build up of filter cake, giving a more consistent moisture content through-out the cake and eliminating cake channeling for better washing results.
- Economy By using the Membrane Plate, lower filtration pressures can be design used. The final moisture content of the cake is determined by the high squeeze pressure up to 16 bar. The result is a reduction of cycle times by as much as 50%.
- The Membrane Plate, when combined with the Chamber Plate maintains all the advantages of membrane filtration, but investment costs for the membrane plate package can be reduced by approximately 50%. Alternative polypropylene are available when severe operating conditions exist.
- EMPTY CHAMBER Design Differential pressure build up and/or uneven slurry may results. initiate insufficient chamber fillings or even empty chambers. Subsequently, damage of the membrane during the squeezing cycle is possible. Many filtration processes differ in size and solids content, so that the risk of an uncontrolled chamber filling is always present.
- For special Empty Chamber Design has been newly developed, Special design measures were developed, so that the membrane is well supported not only during the membrane is well supported not only during the filling phase but as well in the extreme case-squeezing into the empty chamber.
- This prevents an overstretching consequently prevents damage to the membrane. This is confirmed through endurance tests with this special design. After more than 20000 cycles where the membrane was pressed into the empty chamber under 16 bar pressure no damage was visible. This system is especially qualified for filtrations with uncontrolled chamber fillings and variable charge sizes.
- If cake washing is required the chambers have to be filled according to recommendation for standard membrane plates. Underfilling of the chambers can produce inferior washing Overhanging Membrane Plate All the advantages and experiences of the many thousands of welded Membrane Plates In operation were retained in the development of the new Overhanging Membrane Plate, specifically the bending zones of the membrane.
- The Overhanging Membrane Plate is a replaceable membrane plate in the design >>empty chamber << with center feed, which can be used in all applications. It is available with or without stay bosses and allows unrestrictive movement of them membrane.
- It is also adaptable for all core plate materials, i.e. a and ductile iron, aluminum, or polypropylene. It can be used as a mixed pack membrane with recessed chamber plates. The Overhanging membrane has specific strength in the area of the sealing frame to take the closing pressures of the filter press with rubberlike flexibility of the membrane in the drainage area.
- It can be easily replaced in few minutes even after years of operation and without any core mismatch. The replaceable. Overhanging Membrane Plate is an ideal addition to the already successful welded Membrane Plate product line. The Over thinking membrane Plate can be used in any application where high filtration and squeeze pressures are required, especially in modern hi-tech waste water filtration plants.
- Advantages of Membrane Filter Plates Improved washing efficency. When using traditional filter press Shorter filtration time As filtration proceeds the speed with which the cake builds up decreases to elements it an over-proportional extent: When using traditional elements in a filter. press a long period of time (operational point B) is required to achieve a certain residual moisture in the filter cake. When working with membrane filter plates the filtration is well known that often cake washing is not uniform due to the inhomogenous cake built-up (e.g. forming of wash channels”).
- This dis-advantage can be eliminated by slightly compressing the membranes during the washing cycle, thus ensuring a uniform capillary structure in the filter cake. cycle can be terminated earlier (operational point A), the chamber being filled evenly. and completely with filter cake, and the residual moisture in the cake pressing the membranes (operational product purity point C): . Improved washing results higher .
- Reduced washing time less wash Residual cake moisture as a function of squeezing pressure and blowing time. liquid Notably shorter filtration cycle. consumption Cost-efficient disposal (waste water) Homogeneous cake structure – important for efficient cake washing. Improved efficiency: capacity ratio Formular for the optimization of operational point A: Substantially shorter cycle times, i.e. increased output per filter press. or more efficient utilization of existing facilities. max. value The energy saved for subsequent air-blowing is set free for increased drying capacity “K cake volume (dry) in kg RF residual cake moisture in %1 F filtration time in min. Where is the use of NMP membrane filter plates particularly advantageous ? The optimum operational point A can be established after a few filtrations, it is influnced by values such as cake! compressibility, filter cloths, pump. capacity, etc, NMP membrane filter plates can be used by many filtration plants in different fields of application.
- The advantages of employing membrane filter plates become particulary significant where due to specific product properties the membrane. effect can be fully utilizes, ie Reduced residual cake moisture. By squeezing the cake with an inflatable membrane the residual moisture in the filter cake is remarkably reduced. In addition, there are further advantages. for the following process, namely: A Remarkable higher solid contents in the filter cake. • Compressed air hitherto needed for: B cake blowing is no longer required. Influence of membrane squeezing on filtration time noth .
- Less adherance of filter cake on cloth resulting in shorter discharge times, thus improving the automatization of filter press operation. where high filtration pressures were formerly necessary to obtain a qu minimum residual moisture, where long washing cycles must be shortened, washliquid comsumption must be reduced, and costs of waste water must be saved, where not only good but also very uniform cake washing is required, where a high maximum filtrate. recovery is wanted to reduce U product losses, 10 232393019 where the automatization of filter presses is planned in order to reduce manpower and thus labour cost.
- A end of filtration with membrane filter presses B= end of filtration with traditional filter presses C= percentage of residual moisture at end of squeezing (A and C’ are likely to be Influenced by other) Compact and dry filter cakes cut transport costs and minimize transport problems, thus 91819 • Savings in solids disposal, e,g, waste water treatment.
GRAPH OF MEMBRANE
FILTER PLATES
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