JP7283030B2 - Dehydrated cake washing method in filter press - Google Patents

Description

The present invention relates to washing a dehydrated cake, and more particularly to a method for washing a dehydrated cake in a filter press that removes impurities from the dehydrated cake formed in the filtration chambers by supplying washing water through communication passages that communicate with the filtration chambers.

Conventionally, the dehydrated cake formed in the filtration chamber of a filter press used in chemical plants etc. contains impurities such as chlorine. was washing.

Patent Literature 1 discloses a dehydrated cake washing method in which washing water is supplied from one filter plate forming a filtration chamber and the washing water in the filtration chamber is discharged from the other filter plate.

Further, Patent Document 2 discloses a technique of performing cake washing in parallel to each filter chamber from a slurry supply channel for supplying a stock solution in a center feed type filter press in which each filter chamber communicates at the center of the filter plate. there is

Japanese Patent Application Laid-Open No. 2020-082028 JP-A-2003-164711

A method of supplying washing water by connecting a washing water pipe to the filtrate discharge channel of each filtration chamber as in Patent Document 1, and a method of supplying washing water to each filtration chamber through a mud supply channel as in Patent Document 2. can supply sufficient washing water to each filtration chamber, and can push out impurities in the dehydrated cake.

However, the dehydrated cake in each filtration chamber slightly differs in the consolidation state and porosity of the solid matter. When washing water is supplied to each filter chamber in parallel, water passages are formed in the dehydrated cake while pushing out impurities. A large amount of wash water flows into the filtering chamber from other filtering chambers because the pressure resistance of the filtering chamber with wide passage gaps or with a large number of passages formed therein is low. As a result, the amount of impurities removed from the dehydrated cake in each filtration chamber is uneven, and post-treatment of the dehydrated cake requires a great deal of time and money.

The present invention provides a filter press for cleaning dehydrated cake in which cleaning water is supplied from one of the rows of closed filter plates to wash the dehydrated cake in all the filter chambers in series through a communication passage that communicates the filter chambers. To provide a dewatered cake washing method in

The present invention provides a filter press in which a plurality of filter plates are arranged in parallel to form filter chambers between the filter plates, and a step of washing a dehydrated cake is performed by supplying washing water after performing a filtration step in the filter chambers, wherein the adjacent filter chambers A washing water channel is formed through which the washing water passes in series through communication channels formed in each filter plate so that the two are alternately communicated vertically toward the rear stage , and are provided in the undiluted solution supply channel and the filtrate discharge channel. After closing the valve and opening the valves provided in the washing water supply and discharge passages, washing water is supplied from one of the washing water passages and discharged from the other of the washing water passages. There is no increase or decrease in the amount of water supplied to the filtration chamber due to variations in density, and the entire supply amount can be used for washing the dehydrated cake without waste, making it possible to reduce the amount of washing water.

If the supply channel of the washing water channel is a communicating passage that communicates the front end of the filter chamber with the front end of the row of filter plates, there is only one supply port for the washing water, eliminating the need for supply pipes that connect to each filter plate. The number of parts can be reduced.

If the drain channel of the washing water channel is a communication channel that connects the last filter chamber and the rear end of the row of filter plates, there will be only one drainage port for the cleaning water, eliminating the need for drain pipes that connect to each filter plate. , the number of parts can be reduced.

In the method for washing the dehydrated cake in the filter press according to the present invention, since washing water communicates with each filter chamber in series, there is no increase or decrease in washing water to the filter chambers due to variations in the compaction density of the dewatered cake. Therefore, the entire amount of water can be used for washing all the filtration chambers without waste, and a uniform dehydrated cake can be produced, which facilitates the handling of the dehydrated cake in the post-treatment process.

1 is an overall flow chart according to the present invention; FIG. Similarly, it is sectional drawing of a filtration chamber. Similarly, it is sectional drawing of the filter chamber at the time of a dewatered cake washing process. Similarly, it is a cross-sectional view of the filtration chamber during the step of washing the dehydrated cake of Example 2. FIG.

FIG. 1 is an overall flow chart according to the present invention.
Only the dehydration mechanism of the filter press 1 is extracted, and the filter plate 2 configured to be freely movable back and forth is closed to form a filtration chamber 3, and the undiluted liquid containing water is supplied to perform solid-liquid separation. conduct.

A stock solution supply pipe 4 is connected to the front end (left side of the figure) of the filter plate row formed by closing the filter plates 2 , and the stock solution stored in the stock solution storage tank 5 is supplied to the filtration chamber 3 by the stock solution supply pump 6 . The undiluted solution is subjected to solid-liquid separation by pressure feeding by the undiluted solution supply pump 6 or by mechanical compression or the like. A separated liquid (filtrate) is discharged outside from a filtrate discharge pipe 8 via a filtrate pipe 7 connected to each filter plate.

A washing water pipe 9 is connected to the endmost filtrate pipe 7 , and washing water is supplied from a washing water tank 16 into the filtration chamber 3 via a washing water supply pump 10 . It flows into the interior of the dehydrated cake that has undergone solid-liquid separation in the filtration chamber 3 and pushes out impurities in the dehydrated cake.

The wash water that has passed through the dehydrated cake flows into the filtrate pipe 7 together with the impurities in the dehydrated cake, and is discharged to the outside from the filtrate discharge pipe 8 together with the filtrate.

After dehydration and washing are completed, the dehydrated cake from which impurities have been removed is discharged outside by opening the row of filter plates. In addition, you may perform a pressing process after the washing process of a dehydrated cake.

FIG. 2 is a cross-sectional view of the filtration chamber.
A concave filter bed 11 is formed on the filter plate 2 , and a filter cloth 12 is stretched over the filter bed 11 to form a filter chamber 3 between the adjacent filter plates 2 , 2 . An undiluted solution supply channel 13 communicating with the filter plate 2 is provided above the filter plate 2 . The undiluted solution supply path 13 communicates with the undiluted solution supply pipe 4 at the front end of the row of filter plates.

The raw liquid is pressurized into the filter chamber 3 from the raw liquid supply pipe 4 and solid-liquid separated by the filter cloth 12 .
The separated filtrate is discharged to the filter bed 11 of the filter plate 2 , extracted from the filtrate discharge hole 15 provided below the filter bed 11 , and discharged to the filtrate tube 7 . The discharge holes 15 are provided in the front and rear filter beds 11 , 11 facing the filtration chamber 3 , respectively, and the filtrate pipe 7 is communicated with the discharge holes 15 . The other ends of the filtrate pipes 7 are connected to a filtrate discharge pipe 8 through which the filtrate is discharged to the outside.

A communication passage 17 is formed in the filter plate 2 to communicate between the adjacent filter chambers 3 , 3 . The communication path 17 penetrates the inside of the filter plate 2 and communicates from the opening provided in the filter bed 11 to the opening provided in the adjacent filter bed 11 at the shortest distance.

The washing water pipe 9 is connected to the filter plate side of the valve V2 interposed in the filtrate pipe 7 on the front end side of the filter chamber 3 at the front end. Washing water is supplied to each filter chamber 3 in series via 17 . The wash water that has flowed into the final filter chamber 3 is discharged from the discharge holes 15 formed in the filter bed 11 .

In this embodiment, the communication path 17 is formed linearly above the filter bed 11, but it may be formed in the center or below the filter bed 11. FIG. Moreover, as shown in FIG. 4, the upper and lower sides of the filtration chamber 3 may be alternately communicated with each other.

The open/closed state of each valve shown in FIG. 2 represents the state during the dehydration process.
As for the operation of the filter press 1, after the dehydration step (for example, when the undiluted solution is injected), the dehydrated cake washing step is started. In addition, the mechanical pressing step is appropriately performed before and after the dewatered cake washing step as required.

In the dehydration step, the valves V1 and V2 interposed in the undiluted solution supply path and the filtrate discharge path are all open, and the valve V3 interposed in the washing water supply path is closed.

In this embodiment, the undiluted solution supply pipe 4 is provided with a valve V1, each filtrate pipe 7 is provided with a valve V2, the rearmost filtrate pipe 7 is provided with a valve V2r, and the washing water pipe 9 is provided with a valve V3. The opening and closing of the valve during the pressing process is substantially the same as that during the pressurization of the undiluted liquid, but the valve V1 interposed in the feed passage of the undiluted liquid is closed.

The undiluted liquid separated into solid and liquid in the filtration chamber 3 flows into the discharge hole 15 of the filter bed 11 and is discharged to the outside through the filtrate pipe 7 and the filtrate discharge channel 8 .

FIG. 3 is a cross-sectional view of the filter chamber during the dehydrated cake washing process.
After the dehydration process of the undiluted solution is completed, the dehydrated cake washing process is started.
In the step of washing the dehydrated cake in this embodiment, the filter chambers 3 in the row of filter plates are communicated with each other through the communication passages 17 to form the washing water passages WL in series, and washing water is supplied from one of the washing water passages WL. Impurities in the dehydrated cake in each of the filtration chambers 3 are pushed out to the next filtration chamber 3 , and the impurities are discharged together with the washing water from the other of the washing water passages WL.

In the dehydrated cake washing step, the valve V1 interposed in the raw liquid supply path is closed, the valve V3 interposed in the washing water supply path is opened, and the valve V2 interposed in the filtrate discharge path is closed. The valve V2r interposed in the filtrate pipe 7 provided on the rear end side of the last filtration chamber 3 is opened. That is, the filtrate pipes 7, 7 provided at the front end side of the frontmost filtration chamber 3 and at the rear end side of the rearmost filtration chamber 3 are used as the washing water supply pipe and the washing water discharge pipe, respectively, and the washing water is supplied in series. A washing channel WL is formed so as to pass through each filtering chamber 3 .

The washing water supply pump 10 is operated to supply washing water to the filtration chamber 3 from the upstream side of the washing water passages WL formed in series through the washing water pipes 9 . Washing water flows into the frontmost filter chamber 3 through the filtrate pipe 7 and the discharge hole 15 provided at the front end of the row of filter plates.

The wash water that has flowed into the filter chamber 3 winds along the concave portion of the filter bed 11 on the inflow side due to the resistance of the dehydrated cake in the filter chamber 3 . Further, when the pressure increases due to the supply of washing water, it flows into the gaps between the filter cloth 12 and the dehydrated cake.

The washing water that has flowed into the dehydrated cake pushes impurities remaining between particles of the dehydrated cake to the filter bed 11 on the rear end side of the filter chamber 3 .

After that, the wash water spreads along the filter bed 11 on the rear end side of the filter chamber 3 and flows into the next-stage filter chamber 3 through the communication passage 17 connecting the filter chambers 3, 3, and similarly dehydrated cake. Impurities inside are pushed out to the filtration chamber 3 in the next stage.

While sequentially pushing out impurities contained in the dehydrated cake in the filtration chambers 3, the washing water that has passed through the final filtration chamber 3 flows into the discharge holes 15 provided in the filtration bed 11 on the rear end side of the filtration chamber 3, and is filtered. The filtrate is discharged from the liquid pipe 7 to the outside through the filtrate discharge pipe 8 .

In this embodiment, the washing water pipe 9 is connected to the front end of the row of filter plates as a supply channel for washing water. You can extrude.

FIG. 4 is a cross-sectional view of the filtration chamber during the step of washing the dehydrated cake in another embodiment 2. FIG.
In Example 2, a communication passage 17 communicating between the front end of the filter chamber 3 and the front end of the filter plate row and a communication passage 17 connecting the rear end of the filter plate row with the rearmost filter chamber 3 are provided. is communicated with the washing water pipe 9. The washing water pipe 9 f on the front end side is connected to the washing water supply pump 10 , and the washing water pipe 9 r on the rear end side is connected to the filtrate discharge pipe 8 .

Communicating passages 17 serving as wash water supply passages are alternately communicated above and below the filtration chamber 3 toward the rear stage of the filtration chamber 3 . Since the supply port and the discharge port of the washing water to the filter chamber 3 are separated, the front surface of the dehydrated cake in the filter chamber 3 is widely acted upon to efficiently push out the impurities of the dehydrated cake.

In the dehydration process, the valves V1 and V2 interposed in the raw liquid supply path and the filtrate discharge path are all opened, and the valves V3 and V4 interposed in the washing water supply and discharge paths are closed.

After the dehydration process of the undiluted solution is completed, the dehydrated cake washing process is started.
In the dehydrated cake washing step, the valve V1 interposed in the raw liquid supply path is closed, and the valves V3 and V4 interposed in the washing water supply path and discharge path are opened. All the valves V2 interposed in the filtrate discharge path are closed. That is, the washing water passages WL are formed so that the washing water passes through the filtration chambers 3 in series through the communication passages 17 .

The washing water supply pump 10 is operated to supply the washing water to the filter chamber 3 from the front end side of the filter plate row, which is the supply channel, through the washing water pipe 9f. Washing water flows into the foremost filter chamber 3 through a communication passage 17 provided at the front end of the row of filter plates.

The wash water that has flowed into the filter chamber 3 pushes impurities in the dehydrated cake to the filter bed 11 on the rear end side of the filter chamber 3 .

After that, the washing water flows into the filter chamber 3 of the next stage through the communication passage 17 opening to the filter bed 11, and similarly pushes out the impurities in the dehydrated cake to the filter bed 11 on the rear end side. At this time, since the communication passages 17 alternately communicate with the top and bottom of the filtration chamber 3, the dehydrated cake in the filtration chamber 3 is widely affected, and the impurities are efficiently pushed out.

After passing through the final filter chamber 3 , the washing water flows through the communicating passage 17 into the washing water pipe 9 r as the discharge passage and is discharged to the outside through the filtrate discharge pipe 8 .

In Example 2, the washing water is supplied from the front end of the filter plate row and the washing water is discharged from the rear end of the filter plate row. Wash water may be discharged from the front end.

Moreover, the supply channel and the discharge channel of the washing water channel WL may be combined with those of Examples 1 and 2, respectively, and can be appropriately selected according to the specifications of the filter press 1 and the property of the stock solution.

In washing the dehydrated cake of the filter press according to the present invention, since the ventilation passages of the washing water are arranged in series with the filter chambers 3 and the communicating passages, the entire supply amount can be used for washing the dehydrated cake without waste. Uniform washing of the dehydrated cake becomes possible. Therefore, in processes aimed at effectively utilizing dehydrated cake such as sewage sludge or industrial wastewater sludge in which the dehydrated cake is disposed in the post-process, the properties of the dehydrated cake can be stabilized and the time and effort required for the post-treatment process can be reduced. be a useful technique.

1 Filter press 2 Filter plate 3 Filtration chamber 7 Filtrate pipe 17 Communicating passage WL Washing water passages V1, V2, V3, V4 Valve

Claims (3)

A plurality of filter plates (2 . In the filter press (1) performing the process,
Wash water channels ( WL),
Closing the valves (V1, V2) provided in the supply path of the stock solution and the discharge path of the filtrate,
After opening the valves (V2r, V3, V4) provided in the cleaning water supply and discharge channels,
supplying wash water from one of the wash channels (WL);
A method for washing a dehydrated cake in a filter press, characterized in that washing water is discharged from the other of washing channels (WL). 2. The dehydrated cake in the filter press according to claim 1, wherein the supply channel of the washing water channel (WL) is a communication channel (17) that communicates the front end of the filter chamber (3) with the front end of the row of filter plates. cleaning method. 2. The dehydration in the filter press according to claim 1, wherein the discharge channel of the washing water channel (WL) is a communication channel (17) that communicates the last stage filter chamber (3) and the rear end of the row of filter plates. Cake cleaning method.

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