RU2255790C2 - Method of separation of suspensions and press filter for realization of this method - Google Patents

Abstract

FIELD: chemical engineering; filtration of suspensions by means of press filters; chemical, food-processing and other industries.

SUBSTANCE: prior to drying or washing the sediment, drain cavities of plates through which drying gas or flushing fluid is fed are blown with compressed gas. Press filter includes frame with front and rear struts, hold-down plate, filtering plates with grooves on both sides; these grooves have drain cavities provided with filtering partitions. Press filter includes also manifold for delivery of suspension to filtration chambers, filtrate discharge manifolds, as well as manifolds for delivery and discharge of technological media in treatment of sediment; they are formed by angular holes in filtering plates; they are communicated with drain cavities of filtering plates through passages and are connected in pairs by means of vertical bypass pipes; filter is also provided with shut-off fittings mounted in technological media delivery and discharge pipes lines and blowing system for drain cavities of filtering plates; blowing system includes compressed gas delivery main and at least one valve fitted on of vertical bypass pipes in section between manifolds of this pipe. Provision is made for avoidance of mixing of air with drying gas or flushing fluid with liquid media remaining in drain cavities of filtering plates.

EFFECT: enhanced efficiency of drying.

5 cl, 15 dwg

Description

The invention relates to the field of chemical engineering, in particular to the technology of filtering suspensions using filter presses, and can be used in the separation of various liquid heterogeneous systems in the chemical, food and other related industries, as well as in the treatment of industrial and domestic wastewater.

A known method of separating suspensions on filter presses KMP, the work of which consists in sequentially performing technological operations of filtering, pressing the cake, washing the cake and drying it with compressed gas. In this case, the separated suspension, compressed gas for drying the sludge and, if necessary, washing the sludge, the washing liquid enters the filter press through the corresponding valves installed on the supply lines to the same manifold, and from it through the collector supply pipes to the bag filter plates sandwiched between the pressure plate and the stop plate (see. Catalog “Filters for liquids”, TsINTIHIMNEFTEMASH, M., 1991, part II, pp. 5-17).

The disadvantages of this method include the fact that the flows of washing liquid and compressed gas of drying come from the above manifold pipes directly to the free surface of the filtered sludge, which often leads to local destruction of its structure and, as a result, to a sharp decrease in the efficiency of these processes. In addition, in the supply line and supply manifold, on the surface of the sludge, as well as on the surfaces of the filter chambers, at the time of the beginning of the washing and drying operations of the sludge, a significant amount of the liquid phase of the suspension remains, which is mixed with the washing liquid and the compressed drying gas, also reducing their efficiency.

There is also a method of separating suspensions on filter presses chamber type with vertical filter plates. Here, the suspension and the filtrate are carried out through different highways to different manifold pipes. The washing liquid and the compressed drying gas are not supplied directly to the surface of the filtered sludge, but to the corresponding drainage cavity under the filter cloth, which to a large extent protects the sludge from destruction. This has a positive effect on the efficiency of the processes under consideration. However, in the case of these filter presses, a significant amount of the liquid phase remains in the supply line of the washing liquid and, especially, in the drainage cavities, which are designed to receive the washing liquid and compressed gas. Thus, the efficiency of the washing and drying processes in this case also remains not high enough (see. Catalog “Filters for liquids”, M., TSINTIHIMNEFTEMASH, 1991, part II, pp. 22-32).

Closest to the claimed (prototype) is a method in which, before washing and drying the precipitate, the lines are purged to remove residual liquids from them, which undoubtedly increases the efficiency of these processes (see Russian patent No. 2156639, class B 01 D 25/12, publ. 09/27/2000, bull. No. 27).

However, significant amounts of fluids remain in the drainage cavities here. Subsequently, they are mixed with washing liquid or drying air entering the drainage cavities, reducing the effectiveness of washing and drying.

Known filter press KMP, containing a package of horizontal filter plates with filter partitions placed between them. The filter plates are located between the thrust and pressure plates, which, in turn, are included in the filter press frame. The clamping mechanism, also mounted in the frame, is designed to seal the entire package. The structure of the filter press includes lines for supplying slurry, sludge drying air, washing liquid for cases when washing of sludge is required by the technological process, lines for removing the main and washing filtrates, as well as a set of process valves for controlling the process of processing the suspension. The inlet line for such a filter press is formed by remote manifold nozzles and serves both for supplying the suspension and drying air and washing liquid (see. Catalog “Filters for liquids” M., TSINTIKHIMNEFTEMASH, 1991, part II, p. 5 -17).

The latter circumstance leads to the fact that the drying air, passing through the inlet line, is humidified by the moisture remaining in it after suspension and subsequently blows this moisture into the precipitate, reducing the efficiency of its drying process. A similar phenomenon occurs when washing the precipitate, when the washing liquid is enriched with salts from the suspension remaining in the line before entering the precipitate. This leads to the fact that the precipitate is not washed with a clean liquid, but with a solution of salts, and the efficiency of displacing a solution of these salts from the pores of the precipitate is significantly reduced. In addition, as mentioned above, a significant amount of moisture remains inside the chambers of the filter plates, which also negatively affects the quality of drying and washing the precipitate.

Also known is a filter press comprising a stack of vertical filter plates placed on a frame between a front strut and a pressure plate. The pressure plate interacts with the plate clamping mechanism mounted in the rear pillar of the filter press. When the filter plates are compressed into a sealed bag, separate lines are formed in the filter press to supply the suspension and wash liquid from the collector openings provided in the filter plates. This largely eliminates the problems inherent in the previous design (see the catalog “Filters for liquids” M., TSINTIHIMNEFTEMASH, part II, 1991, p.22-32).

However, in horizontally located supply lines, there are still tangible quantities of liquids from previous operations. An additional disadvantage is that in the drainage cavities of the filter plates, liquid residues are also retained, as a result of which the efficiency of washing and drying the sludge is still low.

Closest to the claimed (prototype) is a filter press containing filter plates with a filter cloth placed between them, a collector for draining the filtrate with supply channels made in these plates, a line for supplying a suspension with valves for draining the suspension and washing water, and a line for rinse water supply. This filter press is equipped with an additional manifold for discharging the filtrate, the air supply line has a valve for discharging air, and the washing water supply line is equipped with an air supply valve and is connected to at least one filtrate discharge manifold. In this case, both collectors of the filtrate outlet are interconnected with the possibility of separation (see Russian patent No. 2156639, CL 01 D 25/12, publ. 09/27/2000, bull. No. 27).

The possibility of purging the manifold provided for in this filter press can significantly reduce the residual amount of the main and flushing filtrate in it in comparison with the constructions discussed above. However, such a constructive solution does not eliminate a significant drawback in the operation of the filter press, namely, that before washing and drying the sludge in the drainage cavities of the filter plates there is a significant amount of liquid from the previous operation. Subsequently, this liquid remaining in the drainage cavities is mixed with the flushing liquid or drying air entering here, which reduces the efficiency of the washing and drying of the sludge.

The problem solved by the proposed invention is to create a technology for separating suspensions on a filter press, which allows highly efficient drying operations and, if necessary, washing the filtered sludge by eliminating the mixing of drying air or washing liquid with liquid media remaining in the drainage cavities of the filter plates from previous technological operations.

The problem is solved due to the fact that in the method for separating suspensions, which includes the steps of filtering the suspension in the filter press through the filter baffles with the removal of the formed filtrate from the drainage cavities of the filter plates, drying the filtered sludge by supplying compressed gas to the drainage cavities of the filter plates located on one side of the filter plates chambers, and removal of the latter through the drainage cavities of the filter plates located on the other side of the specified filter chambers, unloading sediment from the filter the p-press according to the invention, before starting to dry the sludge, at least through those drainage cavities that are located on the supply side of the gas for drying, blow compressed gas, which is supplied to these drainage cavities through the upper corner collector openings of the filter plates and in communication with channels, and divert through channels communicating with the lower corner collector holes of the same plates, and then beyond the filter press.

In an advantageous embodiment of the method, in the case of washing the filtered sludge, the washing liquid is passed through the same channels as the compressed gas during drying of the sludge, and before the washing, the drainage cavities of the filter plates are also blown with compressed gas.

In addition, to purge the drainage cavities of the washing plates, a compressed gas line is used to dry the filtered sludge.

Due to the blowing of the drainage cavities of the filter plates with compressed gas according to the path proposed in the inventive method, all the liquid that remained in the indicated cavities from the previous operation is displaced and removed from the filter press, for example, it is connected to the total volume of liquid generated during the previous operation. Therefore, the following operations are carried out - drying the precipitate and, if necessary, washing it without the addition of the indicated liquid residues to the main material flows, and therefore, most effectively.

The passage of the washing liquid in the case of washing the filtered sludge through the same channels as the compressed gas during drying of the sludge, with preliminary blowing of the drainage cavities of the filter plates with compressed gas, ensures high efficiency of the washing of the sludge with the rational use of supply lines for technological fluids.

The use of a compressed gas line designed to dry the filtered sludge, as well as to purge the drainage cavities of the washing plates, simplifies the communication system required to implement the invention.

The implementation of the proposed method becomes possible due to the fact that the filter press used in this case, comprising a frame with front and rear struts, a pressure plate mounted on the frame from the side of the rear rack and interacting with the clamping mechanism of the filter plates, which are located vertically between the pressure plate and the front recessed, while on both sides of each filter plate there are recesses with drainage cavities equipped with filter baffles, a collector for feeding the suspension into the filter chambers I, collectors for drainage of the filtrate, as well as supply and removal of process media during the processing of filtered sludge, which are formed by angular holes in the filter plates, communicate through channels with drainage cavities of the filter plates and are paired with vertical transfer pipes, shutoff valves installed on the pipelines supply and removal of process media, according to the invention, is equipped with a system for purging the drainage cavities of the filter plates, including a supply line for compressed about gas and at least one valve mounted on one of the vertical transfer pipes in the area between the manifolds connected by the specified pipe.

In one of the recommended embodiments of the invention, the valves are installed in areas between the headers of both vertical transfer pipes, said transfer pipes being connected to the compressed gas supply line through shut-off valves.

The presence of a compressed gas supply line and a bypass valve installed in the section of the transfer pipe connecting the manifolds for the removal of process media from the drainage cavities of the washing filter plates makes it possible to efficiently purge the specified drainage cavities before washing and direct drying of the sludge.

An additional installation of a bypass valve in the area of the second transfer pipe connecting the collectors for the removal of process media from the drainage cavities of the press filter plates allows for backwashing and drying of the sludge.

The invention is illustrated by the accompanying drawings, which show:

figure 1 is a General view of the filter press with a schematically shown stop valves;

figure 2 - axonometric projection of the filter press shown in figure 1;

figure 3 - axonometric projection of the filter press shown in figure 1, with another variant of its strapping shutoff valves;

figure 4 is a view along arrow AA on the package of filter plates of the filter press shown in figure 1;

figure 5 is a section of adjacent filter plates along the line a-b-g (see figure 4);

6 is a section of adjacent filter plates along the line A-B-D (see figure 4);

Fig.7 is a sectional view of a packet of filter plates along A-B-D (see Fig. 4) with a schematic representation of a filtering process;

Figs. 8, 9, 10 are a sectional view of a packet of filter plates according to A-B-D (see FIG. 4) with a schematic representation of situations before, during and after a purge of the drainage cavities of the washing plates;

11 - place I figure 9 (increased);

Fig - sectional view of a packet of filter plates according to A-B-D with a schematic representation of the washing process;

Fig - sectional view of a packet of filter plates according to A-B-D with a schematic representation of the process of direct drying of the precipitate;

Fig - sectional view of a packet of filter plates according to BB-D with a schematic representation of the process of blowing the drainage cavities of the press plates;

Fig - sectional view of a packet of filter plates according to A-B-D with a schematic representation of the reverse drying of the sludge (from the drainage cavities of the press plates).

The inventive filter press (Fig. 1) contains a front 1 and a back 2 racks connected by a bridge 3. On the bridge 3 are suspended in pairs alternating press 4 and wash 5 filter plates (Fig. 7), as well as a pressure plate 6. In the back rack 2 of the filter press mounted plate clamping mechanism 7.

In the closed state of the filter press, the filter plates 4, 5 form a single package 8 (figure 1). In this case, the Central holes 9, made in the filter plates, form a reservoir 10 of the suspension (Fig.7). At the same time, filter plates 4, 5 form filter chambers 11, limited on the sides by filtering baffles 12. Filtering baffles 12 are adjacent to the drainage cavities 13 of the washing plates 5 and the drainage cavities 14 of the pressure plates 4. The drainage cavities themselves are alternating protrusions and depressions, the protrusions serve as a support for the filter walls 12, and the troughs are designed for the accumulation and flow of the filtrate.

In the upper corners of the washing and pressing filter plates 5, 4, collector holes 15, 16 are made, respectively, and in the lower corners are collector holes 17 and 18. The collector holes 15, 16 form the upper collectors 19, 20 in the closed filter press, and the collector holes 17, 18 - lower collectors 21 and 22 (Figs. 5-7, 2-3). The filter plates 5 and 4 also contain upper transfer channels 23, 24 and lower transfer channels 25, 26 (Figs. 5, 6, 14).

The upper transfer channels 23 of the washing plates 5 communicate with one end with the drainage cavities 13, and the other end with the upper collector holes 15 of the washing plates. The lower transfer channels 25 of the washing plates 5 are also connected at one end with the drainage cavities 13, and the other end, respectively, with the lower collector openings 17 of the washing plates.

The upper transfer channels 24 of the press plates 4 communicate with one end with the drainage cavities 14, and the other end with the upper manifold openings 16 of the press plates. The lower transfer channels 26 of the press plates 4 are also connected at one end with the drainage cavities 14, and the other end, respectively, with the lower manifold openings 18 of the press plates.

The collectors 19, 21 are interconnected by a transfer pipe 27, and the collectors 20, 22 are connected by a transfer pipe 28.

On the side of the front strut 1 of the filter press (FIGS. 2, 3), process valves are placed with which the suspension separation process is controlled. At the same time, valve 29 is installed on the suspension supply line, valves 30, 31 are on the compressed gas supply lines to the filter press, valve 32 is located on the filtrate discharge line, bypass valves 33, 34 are respectively in the transfer pipe sections 27 and 28 between the manifolds 19 , 21 and 20, 22, and the valve 35 is on the supply line of the washing fluid to the filter press.

Material flows are indicated in the drawings by the following positions: 36 — separable suspension, 37 — filtrate, 38 — filtered precipitate, 39 — washing liquid, 40 — compressed gas, 41 — washing filtrate.

The method of separation of the suspension is carried out on a filter press as follows.

Using the clamping mechanism 7 and the pressure plate 6, the filter plates 4, 5 are compressed into a single package 8 (Fig.1-3). Then open the bypass valves 33 and 34, as well as the valve 32, and close the valves 30, 31 and 35, thereby preparing communications for the removal of the filtrate. After that, open the valve 29 on the suspension supply line and turn on the feed pump (not shown). The separated suspension 36 (Fig. 7) enters the filter press through the manifold 10 and fills the filtration chambers 11 in the filter plates 4, 5. Under the pressure developed by the feed pump, the liquid phase of the suspension passes through the filter baffles 12 into the drainage cavities 13 and 14 of the filter plates 5, 4. The resulting filtrate 37 from the drainage cavities 13, 14 through the channels 23, 25 and 24, 26 (Figs. 5-7), respectively, enters the collectors 19, 21 and 20, 22, and of them into the transfer pipes 27 , 28 (figure 2, 3) and is displayed outside the filter press. The filtered precipitate 38 is retained on the filter walls 12 and gradually fills the filter chamber 11.

By the time the filtration is completed, both drainage cavities 13, 14 of each filter plate 5, 4 are filled with leachate 37. When passing to washing and / or direct drying of the sludge, washing liquid 39 and / or compressed gas should enter the drainage cavities 13 of the washing plates 5 (mainly air) 40. The presence in the drainage cavities of 13 residues of the filtrate (or washing liquid after washing the precipitate) would lead to a decrease in the efficiency of the washing and / or drying processes, since this would necessitate additional Flow rate of washing liquid or air to displace these residues through the thickness of the sediment (which is precisely the case with the prototype).

In order to avoid this drawback, in the proposed method before starting the washing and / or direct drying of the sludge, the bypass valve 33 and the valve 35 are closed and the valve 30 is opened on the compressed air supply line 40 to the washing plates 5 (FIG. 2). Compressed air 40 passes through valve 30 and enters the manifold 19 (Fig. 8). Then, through channels 23, it enters the drainage cavities 13 of the washing plates 5 filled with filtrate 37 (or, in the case of drying performed after washing the precipitate, with washing filtrate). As a result of the pressure generated during this process, the residues of the filtrate 37 are displaced from the drainage cavities 13 into the channels 25 and then to the manifold 21 (Fig. 9), from where they are removed from the filter press through the filtrate exhaust valve 32. Figure 10 shows the state of the drainage cavities 13 after complete removal of the residues of the filtrate 37 from them, in which the drainage cavities 13 are fully prepared for washing and / or direct drying of the sediment.

It should be noted that in all the drawings illustrating examples of the implementation of the claimed method, the movement of material flows in the drainage cavities 13, 14 of the filter plates 5, 4 is indicated by arrows schematically. In fact, the liquid or gas, as well as their mixtures, move mainly in the hollows of the drainage cavities, which is shown for clarity in Fig.11.

To carry out washing of the sludge after the purge of the drainage cavities 13 is completed, the air supply valve 30 and the valve 32 on the filtrate discharge line are closed. At the same time, the flush fluid supply valve 35 and the bypass valve 33 on the transfer pipe 27 are opened (FIG. 2). The washing liquid 39 enters under the pressure of the feed pump (not shown in the drawings) through the valve 35 into the transfer pipe 27, the collectors 19, 21 and further into the channels 23, 25, filling the drainage cavities 13 freed from the filtrate 37 (Fig. 12). After rising in the indicated drainage cavities 13, the washing liquid 39 passes through the thickness of the filtered sludge 38, enters the drainage cavities 14 of the filter plates 4 and leaves the filter press in the form of a washing filtrate 41 through channels 24, 26 and collectors 20, 22.

Direct drying of the precipitate is carried out similarly (Fig. 13), with the only difference being that they close the valve 35 for supplying the washing liquid and open the valve 30 for supplying air to the washing plates 5 (Fig. 2). If the filtered sludge was washed before direct drying, then the drainage cavities 13 of the washing plates were purged again, as was done before the washing (Figs. 8-10).

During direct drying of the sludge, compressed air 40 is pumped through the valve 30 and collectors 19, 21 into the drainage cavities 13, from where it passes through the thickness of the filtered sludge 38, displacing the remaining filtrate 37 (or washing filtrate 41 in the case of washing the sludge) from drainage cavities 14 of the press plates 4. The resulting gas-air mixture rushes through the channels 24, 26 into the collectors 20, 22 and through the transfer pipe 28 is removed from the filter press (figure 2).

In cases where the drying and / or washing of the precipitate is carried out alternately from both the washing 5 and the pressing plates 4, the drainage cavities 14 of the pressing plates 4 are purged as follows (Figs. 3, 14).

Having closed the bypass valve 34 on the transfer pipe 28 and the valve 30, open the valve 31 for supplying compressed air to the press plates 4. Then, through the open valve 31, the manifold 20 and channels 24, pressurized air 40 is pumped into the drainage cavities 14 filled with the filtrate 37 (or, in the case of drying performed after washing the precipitate with washing filtrate 41). As a result of the pressure generated during this process, the filtrate residues are displaced from the drainage cavities 14 into channels 26 connected to the collector 22. From the manifold 22, the filtrate enters the transfer pipe section 28 located below the closed bypass valve 34 and is removed from the filter press.

To conduct reverse drying of the sediment, valve 34 is again opened, as well as valves 33 and 32, leaving the valve 30 for supplying compressed air to the wash plates 5 closed (FIGS. 3, 15). Compressed air 40 is pumped through an open valve 31, collectors 20, 22 and channels 24, 26 into the drainage cavities 14 of the press plates 4. From there, air passes through the thickness of the filtered sludge 38, forcing the remaining filtrate 37 from its pores into the drainage cavities 13 of the washing plates 5. The resulting gas-air mixture rushes through the channels 23, 25 to the collectors 19, 21 and through the transfer pipe 27 and the open valve 32 is removed from the filter press.

After completion of the technological operations for washing and / or drying the filtered sludge, the plate clamping mechanism 7 is activated, which moves the pressure plate 6 to the rear rack 2, opening the bag 8 of filter plates 4, 5 and thereby unloading the sludge from the filter press.

Thus, when drying the sludge, compressed air enters the drainage cavities that do not contain filtrate residues, which significantly increases the efficiency of this technological operation. Similarly, if it is necessary to wash the sludge, the washing liquid does not mix with the remnants of the filtrate in the drainage cavities, which also positively affects the effectiveness of this operation.

It should be noted that the application of the proposed method for the separation of suspensions and the design of the filter press for these purposes is not limited to the above examples, which only illustrate the possibility of implementing the inventions. The proposed method can be used in any other cyclogram of the filtering process, which includes washing and / or drying the filtered sludge, and in almost all designs of filter presses with a closed filtrate outlet and pairwise connected collectors formed by corner openings in the filter plates. At the same time, the strapping of the filter press with shutoff valves may differ from that shown in Figs. 2, 3, but at the same time, do not change the essence of the process of preparing and conducting washing and drying sludge operations and provide the required direction of technological flows. In particular, instead of the bypass valves 33, 34 installed on the sections of the transfer pipes 27, 28 between the collectors connected by these pipes, conventional valves can be used to manually close the connection between the upper and lower collectors while blowing the drainage cavities of the filter plates. The design of the filter plates may also differ from that shown in the drawings. For example, slurry feed openings in said slabs can be offset upward from the center of the slab, and transfer channels can connect the drainage cavities of the same slab with different pairs of collectors.

Claims (5)

1. A method for separating suspensions, including the steps of filtering the suspension in a filter press through filter baffles with the removal of the resulting filtrate from the drainage cavities of the filter plates, drying the filtered sludge by supplying compressed gas to the drainage cavities of the filter plates located on one side of the filter chambers, and draining the latter through the drainage cavity of the filter plates located on the other side of the specified filter chambers, the discharge of sediment from the filter press, characterized in that before the beginning of the drying of the sludge, at least through those drainage cavities that are located on the supply side of the gas for drying, blow compressed gas, which is fed into these drainage cavities through the upper corner collector openings of the filter plates and the channels in communication with them, and is discharged through the channels, communicating with the lower corner collector holes of the same plates, and further beyond the filter press. 2. The method according to claim 1, characterized in that in the case of washing the filtered sludge, the washing liquid is passed through the same channels as the compressed gas during drying of the sludge, while the drainage cavities of the filter plates are also purged with compressed gas before the indicated washing. 3. The method according to claim 1, characterized in that for the purge of the drainage cavities of the washing plates, a compressed gas line is used to dry the filtered sludge. 4. A filter press comprising a frame with front and rear struts, a pressure plate mounted on the frame from the side of the rear rack and interacting with the clamping mechanism of the filter plates, which are located vertically between the pressure plate and the front rack, while on both sides of each filter plate recesses with drainage cavities were provided, equipped with filtering partitions, a collector for supplying slurry to the filtration chambers, collectors for draining the filtrate, and also supplying and discharging process media during filtered sludge, which are formed by angular openings in the filter plates, communicate through channels with drainage cavities of the filter plates and are interconnected by vertical transfer pipes in pairs, shutoff valves installed on the pipelines for supplying and discharging process media, characterized in that it is equipped with a purge system for drainage cavities filter plates, including a compressed gas supply line and at least one valve mounted on one of the vertical transfer pipes a portion between the collectors connected by said pipe. 5. The filter press according to claim 4, characterized in that the valves are installed in areas between the headers of both vertical transfer pipes, said transfer pipes being connected to the compressed gas supply line through shut-off valves.

Images