Pressure filters vertical vessel

Multi (horizontal) element leaf pressure filter, vertical vessel (Sections... 

Horizontal vessel filters with vertical rotating elements have been under rapid development with the aim of making truly continuous pressure filters, particularly for the filtration of fine coal. 

Horizontal or vertical vessel filters, especially those with vertical rotating elements, have undergone rapid development with the aim of making truly continuous pressure filters, particularly but not exclusively for the filtration of fine coal. There are basically three categories of continuous pressure filters available, ie, disk filters, dmm filters, and belt filters including both hydrauHc and compression varieties. 

External-Cake Tubular Filters Several filter designs are available with vertical tubes supported by a filtrate-chamber tube sheet in a vertical cylindrical vessel (Fig. 18-115). The tubes may be made of wire cloth porous ceramic, carbon, plastic, or metal or closely wound wire. The tubes may have a filter cloth on the outside. Frequently a filter-aid precoat will be applied to the tubes. The prefilt slurry is fed near the bottom of the vertical vessel. The filtrate passes from the outside to the inside of the tubes and into a filtrate chamber at the top or the bottom of the vessel. The sohds form a cake on the outside ofthe tubes with the filter area actually increasing as the cake builds up, partially compensating for the increased flow resistance of the thicker cake. The filtration cycle continues until the differential pressure reaches a specified level, or until about 25 mm (1 in) of cake thickness is obtainea... 

Vertical Pressure Leaf Filters are essentially the same as Horizontal Plate Filters except for the orientation of the filter elements which are vertical rather than horizontal. They are applied for the polishing slurries with very lov solids content of 1-5% or for cake filtration with a solids concentration of 20-25%. As with the horizontal plate filter the vertical leaf filters are also well suited for handling flammable, toxic and corrosive materials since they are autoclaved and designed for hazardous environments when high pressure and safe operation are required. Likewise, they may be readily jacketed for applications whenever hot or cold temperatures are to be preserved.The largest leaf filters in horizontal vessels have a filtration area of 300 m and vertical vessels 100 m both designed for an operating pressure of 6 bar. 

During operation the slurry is pumped under pressure into a vessel that is fitted with a stack of vertical leaves that serve as filter elements. Each leaf has a centrally located neck at its bottom which is inserted into a manifold that collects the filtrate. The leaf is constructed with ribs on both sides to allow free flow of filtrate towards the neck and is covered with coarse mesh screens that support the finer woven metal screens or filter cloth that retain the cake. The space between the leaves may... 

Pressure filters are available in either horizontal or vertical tank (vessel) arrangements, with manual or automatic backwashing facilities and with tanks constructed of steel or noncorrosive construction materials. Flow through the filters is normally from the top and then down through the bed. 

These units are sometimes described as pressure vessel filters the vessels used to contain the filter dements are cylindrical designs, positioned vertically or horizontally. These vessels operate in batch mode, with filter cycles similar to plate and fimne filters. The variations available in the type of elements (leaf or candle) and its position in the pressure vessel, lead to a large number of available designs [Purchas, 1981], General operating features of pressure vessel filters have been described [Bosley, 1986] these units are considered to be cleaner and more reliable than other pressure filters, provided adequate attention is given to filter cake properties. 

A multi-element pressure filter comprises a cyhndrical vessel inside which a number of horizontal or vertical porous elements covered by filter cloths are placed (see Figures 1.29 and 1.30). The process suspension, which may be toxic, volatile or flammable, is pumped into the vessel at pressures up to 500 kPa. The positive pressure induces cakes to form on the outer surfaces of the cloths and filtrate is transported away through the elements and a suitable manifold system. Either flat elements, in the form of square, circular or rectangular leaves, or tubular candles are used. They are spaced sufficiently to avoid the possibility of cakes touching on adjacent elements. The pressure... 

Figure 1.29 Cross-sectional views of vertical vessel, multi-element pressure filters with horizontal (left) and vertical (right) leaves. A detailed schematic of the typical filter cycle is shown in Figure 6.2.

Figure 1.30 Cross-sectional view of a horizontal vessel, multi-element pressure filter with vertical leaves showing the in situ and extracted positions of the filter leaves.

Multi-element pressure filters usually comprise a cylindrical vessel inside which a number of horizontal or vertical porous elements covered by filter... 

The tank-leaf pressure filter (Figure 50.4) features a number of leaves (filtering elements) suspended within a closed vessel. Common variations involve the arrangement of the tank and leaves into various vertical and horizontal combinations. Vertical tanks normally contain vertical leaves whereas horizontal tanks may have either vertical or horizontal leaves. The leaves are hollow shells fitted with support grids and covered with a metal gauze or woven fabric. They... 

Pressure Vessel Filters. The several designs of pressure vessel filters all consist of pressure vessels housing a multitude of leaves or other elements which form the filtration surface and which are mounted either horizontally or vertically. With horizontal leaves most suitable where thorough washing is required, there is no danger of the cake falling off the cloth with vertical elements, a pressure drop must be maintained across the element to... 

The vertical cylindrical vessel of the pressure version of the Moore filter developed in France for the sugar industry, which houses a set of radially arranged leaves, is twice the height of the leaves. This allows the leaves to be raised, rotated, and lowered into the different compartments in the bottom half of the vessel. Positive air pressure must be maintained throughout the operation to prevent cake faH-off, and the cake is blown off the leaves by air blowback. 

TDF Drum Filter. This is a fairly conventional dmm filter housed in a vertical pressure vessel. Test data, obtained with the smallest model of only 0.75 m filtration area, is available (18). Larger models have also been announced, ranging up to the filtration area of 46 m and very large vessels. The operating pressures are moderate, up to 25 or 35 kPa, and the dmm speeds fairly conventional from 0.3 to 1.5 rpm. The range of dry cake production quoted is from 250 to 650 kg/m h for fine coal. 

This family of filters consist of a vertical pressure vessel with a horizontal filter plate at the bottom. The filtrate from this equipment flows out a nozzle on the bottom of the filter. These devises are usually used for slurries where large amounts of solids are being collected. Variations of this equipment include equipment with removable lower heads for easy cake removal, ability to pressure or vacuum filter, ability to wash the filter cake, an agitator to break-up and rewash the filter cake, and heating or cooling jackets for the whole vessel. The Nutsche filter is the industrial version of the well known laboratory scale Buchner Funnel with the exception that it is designed to operate under either on vacuum or pressure. 

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