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For more than a century, pressure leaf filters have provided an economic, reliable and proven cake filtration solution for liquids with higher solid loads, between 0.01% – 3%. These highly effective systems consist of pressure vessels containing individual ‘filter leaves’ supported on a manifold.
Liquid is pumped into the pressure leaf filter vessel where it is pushed through the filter leaves, exiting the vessel via the manifold. Solids are retained and form a filter cake on the leaves. When filtration is complete, the filter is drained, leaving the cake on the filter leaves. Depending on the application, the cake can then be sluiced off the leaves or dried and then discharged by a pneumatic vibrator.
Our range of Envi Leaf pressure leaf filters are perfect for both dry and wet cake discharge, in both vertical and horizontal vessel orientations. We provide a range of filter meshes for every filtration step in edible oil production, gelatine processing, liquid sulphur filtration and bio-diesel production. Our top-gauze filter leaves, such as our PZ80, 60 mesh, 24×110 Dutch weave, are ideal for these high-demand industries and are constructed from 316L or 904L stainless steel.
Typical markets and applications include:
Edible oil processing (crude oil, bleached oil, winterised oil)
Glucose, sweeteners, sugar, fruit juice production
Bio-diesel production (pre-treatment and polishing)
Liquid sulphur filtration
Chemicals and oleochemicals
Organic and inorganic salts, amines, resins and bulk drugs
Pressure leaf filter solutions for dry or wet cake discharge
Our range of Envi Leaf pressure leaf filters are designed and engineered using the latest technology to greatly improve cake discharge properties. Envi Leaf long-lasting filter elements require less maintenance and fewer changeovers and repairs, which leads to reduced operational costs, increased productivity and higher filtration efficiency.
Vertical pressure leaf filter
This vertical pressure leaf filter is equipped with vertical, rectangular filter leaves. The filter leaves are mounted vertically and connected to a filtrate manifold at the bottom of the filter tank. For dry cake discharge, a vibrator is used to remove the cake from the filter leaves when the filtration process is complete.
Horizontal pressure leaf filter
Horizontal pressure leaf filters contain filter leaves positioned vertically in a horizontal filter tank. These filters can have a large filtration area and enable visual cake inspection after every cake discharge. An optional vibrator installation can be installed for cake discharge.
Envi Leaf pressure leaf filters deliver:
Space-saving, compact design – these compact systems achieve high flow rates and operate at pressures of up to four bars.
Long-life filter leaves and filter mesh – constructed from five layers (ply) of stainless-steel wire mesh, each internal filter leaf is designed for long-life. Reduced maintenance requirements mean a low total cost of ownership and each leaf offers years of service.
High-efficiency – with excellent pre-coating properties.
Adaptability – Envi Leaf pressure leaf filters can be sized according to your application – with vertical vessels ranging from 5m2 to 125m2.
Multi-purpose – one system can be used at multiple stages in the filtration process, customised by the mesh and the structure of the filter leaves within.
Quicker discharge – our air vibration system ensures quick and easy cake discharge. With fast drying processes, we ensure the minimum amount of liquid wastage during cleaning cycles.
Enhanced robust design – our enhanced nozzle has a unique u-shaped profile and is enclosed within a manifold. This design creates a strong bond with the tank, delivers a smooth flow and prevents damage during cleaning.
Safe operating – the completely closed filter body ensures safe operating conditions at high temperature.
Order pressure leaf filter spare parts with our flexible stocking programme
A safe and secure supply of spare parts and replacements is an essential part of any manufacturing operation. With our flexible stocking programmes and technical expertise and advice, we’ll ensure delivery of spare parts and replacements when you need them, minimising interruption to your production cycle. We will work with you to develop a stocking system to meet your needs. Spare parts for pressure leaf filters can be held on your site or we can provide immediate dispatch from our warehouses for fast delivery.
Tailored filtration solutions to meet your needs
Selecting the right pressure leaf filter technology for your application will depend on many factors like the flow rate, continuous or batch processing, the type and amount of solid load, the nature of the liquid, the temperature and the liquid viscosity.
Premature screen failure
One of the most common problems that operators face with their vibrating separator is premature screen failure. Vibratory separator screens are considered a wear item in that they’ll eventually wear out and need replacing. Unfortunately, a screen’s life is dependent upon many variables, such as the material type it comes into contact with, any environmental extremes, cleaning methods used with it, etc., so it’s not easy to say how long a separator screen should last without taking those factors into consideration. However, you should get plenty of use out of your screen before needing to replace it.
Delamination. There are many possible causes for premature screen failure. If a screen is delaminating or separating into layers on the tension ring, this could indicate a temperature issue. Every screen manufacturers’ temperature limits differ for epoxy-mounted screens. Some limits are as low as 120oF (49oC) while others are as high as 200oF (93oC). If the material temperature exceeds the screen’s limit, the epoxy will begin to weaken and fail, causing the screen to delaminate. The pH level of the materials being processed also needs to be taken into account, as it affects the screen. Materials with a high pH level of 10 or more tend to decrease the epoxy’s temperature resistance, causing a screen to delaminate even at temperatures within the manufacturer’s given limits. If you think you might encounter this problem because your process requires separating materials at a high temperature greater than the screen manufacturer’s limits, consider using a welded screen if possible. A welded screen can withstand temperatures up to 400oF (204oC). This screen type isn’t always an option for food and other sanitary applications, so be sure to speak with the screen manufacturer to find out about other options; however, these same issues can occur with differing screen types.
Breakage. The center of the separator screen is another focal point for premature failure. To minimize the risk of screen failure at the center of the screen, there are a few things that should be checked. If working with a larger screen that uses a center tie-down, ensure that the tie-down is holding the screen level. An unlevel screen could put unwanted stress on the mesh around the center disc, causing the screen to tear. Also, make sure the center tie-down assembly is tightened properly. The assembly should only be tightened after the exterior clamp ring assembly is seated and fully torqued. If tightened incorrectly, this too could put added stress on the screen mesh, leading to early screen failure. The screen’s center should also be watched to ensure material doesn’t congregate there. If this happens, the screen mesh will wear at that point, leading to breakage. An incorrect lead angle is the likeliest cause of center congregation. The lead angle is the number of degrees separating the motor shaft’s bottom weight assembly resultant force and the top weight assembly resultant force. To fix an incorrect lead angle, the weight settings and lead angle need to be adjusted to move the materials off the screen. Another common reason for center screen failure is a feed surge to the screen. When this occurs, the screen’s center is flooded with material, and the weight of the material compromises the integrity of the mesh, causing the screen to tear or wear out. To eliminate this possibility, the vertical drop of the feed can be reduced for dry applications or a velocity reducer can be installed for wet applications, including slurries.
What Are the Benefits Dewatering Equipment?
Adding dewatering equipment can effectively remove moisture from the final product and capture tiny particles in the wastewater, resulting in drier material. In addition, the removed water can be efficiently recycled back through the manufacturing or processing plant. No matter the industry, the overarching goal of dewatering screens is to deliver the cleanest possible filtrate and driest possible solids.
In addition to creating a drier material, using dewatering equipment offers a range of other benefits. For starters, dewatered material is much easier to handle and can lead to cost savings in transportation.
Material that is dewatered also reduces the drying time of the stockpile, which can free up valuable space at your facility. In some instances, dewatering equipment can reduce or outright eliminate the need for a settling pond. Sand dewatering equipment can lower the amount of material designed for a settling pond.
How Does a Dewatering Screen Work?
The dewatering screen design is relatively simple. The majority of dewatering screen systems utilize two counter-rotating vibrating motors, while some utilize twin eccentric shafts. At the same time, other types of dewatering screens employ multiple mechanical exciters on larger machines that are mounted on a stressed relieved bridge. The drive component is typically set up with an inclined deck that may be set anywhere from three to five degrees. Here’s how dewatering screens work to reduce the water content of slurries:
The slurry of water and solids is sent down a declined, steeply screened surface to achieve rapid drainage.
When the slurry passes over the screens, water is drained from the mixture and creates a pool in the valley.
As the slurry moves through the system, it is taken back up an incline. The screens continuously vibrate throughout the process to help additional water separate from the solution.
An uphill slope of the screen surface can be combined with a discharge weir to create a deep bed that functions as a filter medium. This allows for even finer solids to be screened out.
If you would like an even more refined, cleaner product, you can use a rinsing station along the pathway. The sand dewatering equipment can remove the water used for rinsing just as it separates the water from the slurry.