Cake discharge diameter

Filtration and compression take place with the press closed and the belt stationary the press is then opened to allow movement of the belt for cake discharge over a discharge roUer of a small diameter. This allows washing of the belt on both sides (Fig. 15). Cycle times are short, typically between 10 and 30 minutes, and the operation is fully automated. Si2es up to 32 m are available and the maximum cake thickness is 35 mm. 

The Gaudfrin disk filter, designed for the sugar industry and available in Prance since 1959, is also similar in design to a vacuum disk filter but it is enclosed in a pressure vessel with a removable Hd. The disks are 2.6 m in diameter, composed of 16 sectors. The cake discharge is by air blowback, assisted by scrapers if necessary, into a chute where it may be either reslurried and pumped out of the vessel or, for pasty materials, pumped away with a monopump without reslurrying. 

Cake discharge occurs at atmospheric pressure by the action of a toU or a scraper, assisted by blowback. The cloth may be washed by a spray before the cycle starts again. Filtering areas range up to 8 m and dmm diameters up to 2 meters. The necessity for large seals limits the operating pressure to less than 300 kPa, typically. Cake thickness can be from 2 to 150 mm, depending on machine size, and the speed of dmm rotation up to 2 rpm, usually from 0.3 to 1 rpm. Apphcations occur in the manufacture of pharmaceuticals, dyestuffs, edible oils, and various chemicals and minerals. 

Dry cake discharge can be achieved with a Fnndabac candle-ty e ter uses a candle made up of six small-diameter tubes around a central... 

Dry cake discharge can be achieved with a Fundabac candle-type filter manufactured by DrM, Dr. Muller, AG, of Switzerland. This filter uses a candle made up of six small-diameter tubes around a central filtrate delivery tube. This design allows the filter cloth to be flexed outward upon blowback, easily achieving an effective dry cake discharge (Fig. 18-129). 

EfiScient cake discharge can be effected by separation of the belt fi om the cloth and directing the latter over a set of discharge roUws. Here a sharp turn in cloth travel, over a small diameter roller produces cake cracking and discharge. Another area which has received attention, is that of the control of the down-stream pressure drops which ensue with the two-phase flow of air and water through the vacuum system. 

The maximum speeds of basket centrifuges with cake discharge filter bag pullout or manual digging vary from 1200 to 2100 rpm (some have two-speed drives), and basket diameters are in the range from 500 to 1250 mm. A 1200 mm diameter, 750 mm long basket may handle as much as 200 kg of cake in one charge. Interlocks and inert gas blanketing may be used. 

The centrate and cake discharge at approximately the same diameter and therefore it is not necessary to work out the components of power for these two streams separately. Were the discharge diameters to be markedly different, then the rate for each stream would need to be calculated, and equation (4.131) would then need to be used for each stream. 

The column headed beach dia refers to the diameter at the cake discharge. The total liquid volume" is the bowl s liquid holding capacity with the pond set at neutral. The maximum bowl speed tabulated is that quoted by the manufacturer for a maximum process density of 1.2 kg/1, unless otherwise stated. 

The column headed "beach dla" refers to the diameter at the cake discharge. 

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