Pressure filters horizontal vessel

Multi (vertical) element leaf pressure filter, horizontal 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. 

Normally the filter strueture consists of a stack of plates attached to a hollow shaft which are mounted inside a pressure vessel with eaeh plate eovered with a suitable filter medium. The slurry is fed under pressure into the vessel and the eake, which is retained by the filter medium, forms on the top of eaeh plate whilst the filtrate passes through the hollow shaft further to the proeess. Filter sizes may vary but generally the maximum is 60 m area and designed for a 6 bar operating pressure. Each circular plate in the staek is eonstructed with radial ribs that are welded to the bottom and support a horizontal eoarse mesh screen whieh is eovered with a fmer woven metal screen or filter cloth to retain the cake. The bottom of the plate slopes towards the hollow eentral shaft whieh lets the filtrate flow freely through circumferential holes and further down the shaft to the filtrate outlet. The elearanee between the plates is maintained by speeial spacers... 

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. 

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... 

Another development of the disc filter has been reported more recently from KHD Humboldt Wedag AG . A somewhat different system, probably a predecessor, was also patented by the same company. The patented sys-tem has stationary discs mounted inside a pressure vessel (horizontal vessel, vertical discs) which is mounted on rollers and can rotate slowly about its axis. A screw conveyor is mounted in the centre of rotation but this is stationary it conveys the cake, which is blown-off the leaves when they pass above the screw, to one end of the vessel where it falls into a vertical chute. The cake-discharge system involves two linear slide valves which slide the cake through compartments which gradually depressurize it and move it out... 

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... 

A test unit has been developed of a small dmm filter, total filter area of 0.7 m with 30% submergence, housed in a large horizontal pressure vessel. 

A plate-type filter, the PDF filter (18), uses a paddle wheel with radial, longitudinal plates coveted with filter cloth and manifolded to the filter valve at one end of the vessel, instead of a dmm. This filter uses a horizontal pressure vessel, was built to have only 0.75 or 1.5 m area, and operates at 25 kPa. A central screw conveyor collects the cake blown off the plates and conveys it to the discharge end of the vessel. 

A horizontal belt filter has been used in place of the small dmm filter in filtration studies (17). The entire filter was placed in a large pressure vessel with no moving parts passing through the filter shell. There is no commercial filter based on this principle the utilization of the space inside the pressure vessel would be poor and the filtration areas limited. 

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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