Vacuum filters continuous

Most continuous vacuum filters are the constant pressure type. Their main use is in dewatering concentrated slurries such as concentrates. They belong to three classes the disk, dmm, and horizontal filters. Disk, and to a lesser extent, dmm filters, are the mainstay for most final dewatering. These filters remove most fine particles from a process stream. 

Pressure leaf filters are used to separate much the same lands of slurries as are filter presses and are used much more extensively than filter presses for filter-aid filtrations. They should be seriously considered whenever uniformity of production permits long-time operation under essentially constant filtration conditions, when thorough washing with a minimum of hquor is desired, or when vapors or fumes make closed construction desirable. Under such conditions, if the filter medium does not require frequent changing, they may show a considerable advantage in cycle and labor economy over a filter press, which has a lower initial cost, and advantages of economy and flexibility over continuous vacuum filters, which have a higher first cost. 

Filter application Continuous vacuum filters Multicompartment drum Single compartment drum Top feed drum Scroll discharge drum Tilting pan Belt Disc... 

Continuous vacuum filters, 16 657 Continuous vacuum pans, for raw sugar crystallization, 23 449 Continuous veno-venous hemodiafiltration (CWHD), 26 832... 

The disadvantages of cyclic operation, attributable to the need to remove the cake from batch filters, have been largely overcome by the development of a wide range of continuous vacuum filters as summarised in Table 7.2 which includes data on the selection for a given duty. This is further detailed in Table 7.3 and is based on the work of G. H. Duffield of Stockdale Engineering and E. Davies of ED ACS Ltd. 

The chilled oil-naphtha solution containing crystallized wax and the filter aid is then filtered by means of a continuous vacuum filter or an intermittent pressure leaf filter. Increased dewaxed oil yields are realized by applying a cold naphtha displacement wash to the wax cake on the filter. The pour point of the dewaxed oil is usually 25° to 35° F. higher than the filtering temperature. 

Filtration. The suspension of cyclonite in nitric acid passes through a pipe 7.5 cm in diameter to a continuous vacuum filter (Fig. 23, 24) encased in stainless steel. The casing is connected with the suction system that conveys nitric oxides to the absorption towers. 

TABLE 11.12. Sizes of Commercial Continuous Vacuum Filters... 

Equipment type (A) filter press (B> leaf pressure filters, such as Kelly, Sweetland, etc. (C) continuous vacuum filter (D) batch rotary filter (E) continuous rotary filter. 

TABLE 11.14. Design and Operating Factors for Continuous Vacuum Filters (a) Typical Factors for Cycle Design... 

In this type of filter, the pressure differential across the filter is achieved by imposing a vacuum on the downstream side, rather than pressure on the upstream side. Both batch and continuous vacuum filters are widely used in... 

The PFTN suspended in the spent acid overflows from the second nitrator into a continuous vacuum filter (7). Tlie spent acid goes through a filter into an intermediate vacuum tank equipped with a strainer retaining all the PHTN which may escape from the filter. From the tank the acid is pumped to storage by means of a diaphragm pump controlled by a level switch in the intermediate vacuum tank. 

A description of crystallization as given by Hiazzi SA (I8 is as follows. PETN is continuously introduced from the filter into a stainless steel dissolving apparatus provided with a hot water healing jacket and a stirrer. The required amount of acetone is continuously fed from a constant-level overhead tank together with ammonia gas for neutralization. The neutralized solution of PETN in acetone fiows continuously into a series of continuous crystallizers equip(>cd with stirrers and jackets. The crystallization is earned out by adding a welt determined quantity of water. The contents of the last crystallizer flow continuously on a continuous vacuum filter where most of the waste acetone is removed. I hc dilute acetone is collected into an intermediate vacuum tank from which it is pumped to the acetone recovery unit. 

The acid RDX/water slurry flows into a continuous vacuum filter, the transport water is drawn througli the filter into an intermediate tank with a strainer... 

Vacuum Filters, Continuous Type.— Vacuum leaf filters which dipped into a tank or basin of the material to be filtered were the predecessors in point of time of the continuous rotating vacuum filters of today, practically the only type of continuous vacuum filter which exists today. The old leaf type of vacuum filter was intermittent in operation and one of two sets of operations were necessary with them (omitting for brevity the washing operations). In one set the leaves were stationary and after the tank or basin was filled suction was applied and a cake of the proper thickness accumulated. It was then necessary to run off the balance of the material in the tank or basin, reverse the air current and blow off and wash out the cake which had accumulated. After this was done fresh material was allowed to enter and the cycle of operations was repeated- In the other set of operations and better from a mechanical point of view the filter leaves with their accumulated cake were removed by machinery and after the cake was dropped the leaves could be returned to the tank for further solid accunaulation. 

Comments Vacuum belt. Tilting pan, Continuous Vacuum filter, Batch cartridge,... 

Batch, semi-batch vacuum filters Continuous vacuum filters Batch, semi-batch pressure filters Continuous pressure filters Compression filters Filtering centrifuges Precoat filters... 

As shown in Fig. 11.1-1, the solids—liquid separation device is the link between the solids formation equipment and the diying operation, Thus, predictable and reliable operation is essential in this stage of the processing sequence. Continuous or baich-automatic centrifuges nad continuous vacuum filters are typically used to recover solid material from continuous crystal I ization operations. Many factors are considered in [ha final selection of the device. In any case, an equipment testing program is always essential to determine the capacity and performance of solids separation equipment. 

Rotary-drum filter. The most common type of continuous vacuum filter is the rotary-drum filter illustrated in Fig. 30.8. A horizontal drum with a slotted face turns at 0.1 to 2 r/min in an agitated slurry trough. A filter medium, such as canvas, covers the face of the drum, which is partly submerged in the liquid. Under the slotted cylindrical face of the main drum is a second, smaller drum with a solid surface. Between the two drums are radial partitions dividing the annular space into separate compartments, each connected by an internal pipe to one hole in the rotating plate of the rotary valve. Vacuum and air are alternately applied to... 

Equations (30.32) and (30.33) apply both to continuous vacuum filters and to continuous pressure filters. When R is negligible, Eq. (30.33) predicts that the filtrate flow rate varies inversely with the square root of the viscosity and of the cycle time. This has been observed experimentally with thick cakes and long cycle times with short cycle times, however, this is not true and the more complicated relationship shown in Eq. (30.32) must be used. In general, the filtration rate increases as the drum speed increases and the cycle time diminishes, because the cake formed on the drum face is thinner than at low drum speeds. At speeds above a certain critical value, however, the filtration rate no longer increases with speed but remains constant, and the cake tends to become wet and difficult to discharge. 

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