JP3773130B2 - Solid-liquid separation method and rotary cylindrical vacuum filter using the same - Google Patents

Description

【００５０】
表１からも明らかなとおり、従来型の回転円筒型真空濾過機ではケーキ含水率を１０％以下にすることは不可能であるが、本発明の回転円筒型真空濾過機では可能であった。さらに、本発明の回転円筒形真空濾過機を使用した設備の設置面積は、水平ベルト型真空濾過機および竪型遠心分離機を使用した設備の４２．４〜３５．０％で済み、設備の省スペース化を図れる。また、本発明の回転円筒型真空濾過機は、その動作電力量は、従来の回転円筒型真空濾過機に比べて弱冠増加するものの、水平ベルト型真空濾過機の約７４％、竪型遠心分離機の約３５％で済み、ランニングコストを抑えることが可能である。
【００５１】
本実施例では、排煙脱硫スラリーから石膏を分離する場合を示したが、本発明はこれに限定されるものではなく、例えば、ビスフェノール、テレフタル酸等の製造に使用しても同様の結果となることは、実施例を示すまでもなく、当業者が容易に理解できるものである。
【００５２】
【発明の効果】
以上のとおり、本発明によれば、低含水率のケーキが得られるとともに、装置コスト、装置のランニングコスト、および装置の設置スペースを低減するなどの利点がもたらされる。
【図面の簡単な説明】
【図１】 本発明の第１の態様を示す縦断面図である。
【図２】 その横断面図である。
【図３】 本発明の第２の態様を示す縦断面図である。
【図４】 本発明の第３の態様を示す縦断面図である。
【図５】 その類似例を示す縦断面図である。
【図６】 本発明のその他の態様を示す縦断面図である。
【図７】 従来の回転円筒型真空濾過機の概要を示す縦断面図である。
【符号の説明】
１…スラリー貯留槽、２…ドラム、３…濾過室、１２…スラリー攪拌手段、１３スラリー供給タンク、Ｓ…スラリー、Ｃ…ケーキ。[0001]
BACKGROUND OF THE INVENTION
In particular, the present invention relates to a solid-liquid separation method in which a cake having a low water content is obtained and the apparatus cost, the running cost of the apparatus, and the installation space of the apparatus are reduced, and a rotary cylindrical vacuum filter using the same.
[0002]
[Prior art]
Conventionally, in a method for producing gypsum, bisphenol, terephthalic acid, etc., since the product is obtained as a slurry dispersed in a reaction solvent or the like, various filters are used to separate the product from this slurry. Yes. Among these filters, the rotary cylindrical vacuum filter is particularly widely used because it is relatively inexpensive and has a high filtering capacity per unit installation area.
[0003]
An outline of the rotary cylindrical vacuum filter will be described with reference to FIG. 7. A partition member for forming a slurry storage tank 20 having an upper part opened and having a slurry supply port 21 in a lower part and filtration chambers 31, 31. And a cylindrical drum 30 on which a filter cloth 33 is stretched through 32, 32..., And the drum 30 is supported in a lateral arrangement so that a part of the drum 30 is immersed in the slurry storage tank 20. It is rotated clockwise. 34 is a filler filled between the partition members 32, 32.
[0004]
Further, the filtration chambers 31a, 31a ..., 31b, and 31, 31 ... communicate with automatic valves (not shown) through filtrate pipes 40a, 40a ..., 40b, and 40, 40 ..., respectively. The filtration chambers 31, 31,... And 31a, 31a,... Excluding the portion where the cake is scraped off by a scraper 50, which will be described later, are configured to be sucked at all times and to act on the vacuum pressure.
[0005]
Further, cleaning liquid spray pipes 60 and 60 are provided facing the surface of the filter cloth 33 rotating and moving from the slurry storage tank 20. A scraper 50 for scraping the cake C is disposed at a position spaced upward from the rear side of the slurry storage tank 20 in the rotation direction of the drum 30.
[0006]
Solid-liquid separation of the slurry S in the slurry reservoir 20 is performed as the drum 30 rotates clockwise in the drawing.
[0007]
First, as the drum 30 rotates, the slurry S in the slurry storage tank 20 is filtered by a filtration chamber 31a, 31a located in the slurry storage tank 20 via a filtrate pipe 40a, 40a and an automatic valve (not shown). As a result of being sucked by the pressure and the vacuum pressure state, cake C is picked up on the filter cloth 33 surface. The cake C attached to the surface of the filter cloth 33 moves as the drum 30 rotates in the clockwise direction. Next, the cleaning liquid is projected from the cleaning liquid spray pipes 60 and 60 to the cake C on the filter cloth 33 transferred from the slurry storage tank 20 to perform cleaning, and a vacuum pressure is applied in the filtration chambers 31, 31. Because of the working relationship, the cleaning liquid is sucked and filtered and discharged through the filtrate pipes 40, 40.
[0008]
When the drum 30 further rotates and the cake C after washing and filtration reaches the site of the scraper 50, compressed air is supplied through the filtrate pipe 40b into the filtration chamber 31b at the position, and this compressed air passes through the filter cloth 33. The cake C is peeled off (blowback), and the cutting edge 50a of the scraper 50 comes into contact with the filter cloth 33 swelled by the compressed air, and the cake C5 is scraped and discharged.
[0009]
Thereafter, the process returns to the cake pick-up process described above, and the same process is repeated.
[0010]
[Problems to be solved by the invention]
However, in such a conventional rotary cylindrical vacuum filter, a cake having a sufficiently low water content cannot be obtained due to the atmospheric pressure or pressurization of the filtration chamber when the cake is discharged.
[0011]
That is, when the pressure in the filtration chamber is reduced to the atmospheric pressure when the cake is discharged, the liquid component adhering to the filter cloth is absorbed again into the cake by capillary action, and the moisture content of the discharged cake increases.
[0012]
The filtrate pipe sucks the filtration chamber to reduce the vacuum pressure and functions as a passage when discharging the filtrate, and functions as a passage when supplying compressed air into the filtration chamber to discharge the cake. Therefore, when the cake is discharged, the filtrate adhering to the filtrate pipe is blown back to the cake through the filter cloth along with the pressurized air supplied into the filtrate pipe, and as a result, The moisture content will be high.
[0013]
On the other hand, a horizontal belt type vacuum filter and a vertical centrifuge are known as those capable of obtaining a cake having a low water content.
[0014]
However, the horizontal belt type vacuum filter has a large apparatus floor area per unit filtration area, and it is necessary to secure a larger installation space than the rotary cylindrical vacuum filter. Furthermore, in the horizontal belt type vacuum filter, in order to reduce the moisture content of the cake, it is necessary to enlarge the filtrate suction pump, which increases the apparatus cost and the running cost of the apparatus.
[0015]
In the vertical centrifuge, there is a problem that the filtration capacity per unit is low. In particular, when the same filtration capacity as the rotary cylindrical vacuum filter and the horizontal belt vacuum filter is required, it is necessary to install a plurality of vertical centrifuges. The running cost increases and the installation area also increases.
[0016]
Therefore, a main problem of the present invention is to obtain a cake having a low water content and to reduce the apparatus cost, the running cost of the apparatus, and the installation space of the apparatus.
[0017]
[Means for Solving the Problems]
Among the present inventions that have solved the above problems, the invention according to claim 1 is a slurry storage tank having an open top, a drum filter medium in which a filter cloth is stretched through a filter chamber on the outer peripheral surface of a cylindrical drum, and means for applying a vacuum and pressure to the filtration chamber of the drum filter medium, the drum filter medium rotates a part of which is arranged to rotate in a state of being immersed in the slurry of the slurry storage tank Use a cylindrical vacuum filter,
In accordance with the rotation of the drum filter medium, the following steps (a) to (c) are performed for each rotation.
(a) A cake forming step of forming a cake on the drum filter medium by applying a vacuum pressure to the inside of the drum filter medium located in the slurry storage tank.
(b) While a vacuum pressure is applied to the cake on the drum filter medium, a cake having a predetermined thickness is removed from the cake surface so that a part of the cake remains on the drum filter medium. Scraping process.
(c) After the residual cake on the drum filter medium is immersed in the slurry of the slurry storage tank , and the entire filtration chamber where the residual cake is located is immersed in the slurry, the entire cake is immersed in the slurry. A step of pressurizing the inside of the filtration chamber to blow back the residual cake on the drum filter medium into the slurry of the slurry storage tank .
[0018]
In the invention according to claim 2, after the cake is scraped off in the step (b) and before the residual cake is immersed in the slurry in the slurry storage tank in the step (c) , The solid-liquid separation method according to claim 1, wherein the inside of the drum filter medium to which the residual cake is attached is set to atmospheric pressure, and the slurry substantially the same as the slurry in the slurry storage tank is projected onto the residual cake on the drum filter medium. It is.
[0019]
The invention according to claim 3 is the drum filter medium after the cake is formed on the drum filter medium in the step (a) and before the cake is scraped off in the process (b). The solid-liquid separation method according to claim 1 or 2, wherein steam is supplied to the upper cake.
[0020]
In the invention according to claim 4, after the cake is formed on the drum filter medium in the step (a) and before the cake is scraped off in the process (b) , The solid-liquid separation method according to claim 1, wherein hot water is supplied to the cake to wash the cake with hot water.
[0021]
The invention according to claim 5 is characterized in that the liquid content of the cake scraped in the step (b) is 8 to 10 wt% with respect to the solids in the cake. The solid-liquid separation method according to claim 1.
[0022]
The invention described in claim 6 is a slurry storage tank having an open top, a drum filter medium in which a filter cloth is stretched on the outer peripheral surface of a cylindrical drum through a filter chamber, and a vacuum pressure and a pressure in the filter chamber of the drum filter medium. A rotary cylindrical vacuum filter disposed so as to rotate in a state in which a part of the drum filter medium is immersed in the slurry of the slurry storage tank.
As the drum filter medium rotates,
Means for applying a vacuum pressure to the inside of the drum filter medium located in the slurry storage tank to form a cake on the drum filter medium;
Means for scraping a cake of a predetermined thickness from the cake surface so that a part of the cake remains on the drum filter medium while a vacuum pressure is applied to the cake on the drum filter medium inside the drum filter medium When,
After the residual cake on the drum filter medium is immersed in the slurry of the slurry storage tank , and the entire filtration chamber in which the residual cake is located is immersed in the slurry, the entire filtration chamber is immersed in the slurry. A rotary cylindrical vacuum filter provided with means for pressurizing and blowing back the residual cake on the drum filter medium into the slurry of the slurry storage tank .
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.
[0024]
<First aspect>
1 and 2 show a rotary cylindrical vacuum filter (hereinafter referred to as a first embodiment) to which the solid-liquid separation method according to claim 1 is applied. The apparatus configuration is based on a conventional rotary cylindrical vacuum filter (see FIG. 7). In particular, the scraper 11 is disposed such that the blade edge 11a is separated from the surface of the filter cloth 2b by a predetermined distance. Of the filtration chambers immersed in the slurry S of the slurry storage tank 1, the automatic valve member 8 sends the compressed air to the filtration chambers 3b, 3b on the rear side in the rotational direction, and the filtration chambers 3a, 3a at other positions. And 3, 3,... Are always sucked so that a vacuum pressure acts.
[0025]
That is, the first mode is provided with a slurry reservoir 1 having an upper part opened and a slurry supply port 1a at a lower part, and partition members 2a, 2a,. And a cylindrical drum 2 on which a filter cloth 2b is stretched. The drum 2 is arranged in a lateral direction so that a part of the drum 2 is immersed in the slurry storage tank 1, and the shaft bodies 4a and 4b and the bearing 5a. , 5b is rotatably supported on the slurry storage tank 1. 2c and 2c are stainless steel bands for fixing the filter cloth 2b to the outer peripheral surface of the drum 2 via the partition member 2a, and 2d and 2d are fillers filled between the partition members 2a.
[0026]
A sprocket 6a is provided on the shaft body 4a on one side and is connected to the main rotation driving means 6 via an endless chain 6b, whereby the drum 2 is rotated clockwise in the figure. An automatic valve member 8 is in intimate contact with the shaft 4b on the other side via a pipe plate 7 in the direction of the rotation axis, and the filtration chambers 3a, 3a, 3b, 3b and 3, 3. Are configured to communicate with each other by respective filtrate pipes 9a, 9a, 9b, 9b and 9, 9... Disposed through the drum 2, the shaft body 4b and the pipe plate 7. Here, the automatic valve member 8 is immersed in the slurry S of the slurry storage tank 1 through the pipe plate 7 and the filtrate pipes 9a, 9a, 9b, 9b and 9, 9,. Of the filtration chambers, compressed air is sent to the filtration chambers 3b, 3b on the rear side in the rotational direction, and the filtration chambers 3a, 3a, 3, 3,. Yes.
[0027]
Further, the scraper 11 for scraping the cake C is disposed at a position spaced upward from the rear side of the slurry storage tank 1 in the rotation direction of the drum 2 so that the blade edge 11a has a predetermined separation distance from the surface of the filter cloth 2b. Arranged.
[0028]
In the slurry storage tank 1, a slurry stirring means 12 is provided in which a blade 12b is fixedly provided on a shaft body 12a arranged substantially horizontally along the axial center of the shaft body 12a. One end of the slurry agitation means 12 is connected to a sub-rotation drive means 12c disposed outside the slurry storage tank 1, and is rotated by the sub-rotation drive means 12c.
[0029]
In addition, a slurry supply tank 13 is provided as a slurry supply system for supplying the slurry to the rotary cylindrical vacuum filter. The slurry in the slurry supply tank 13 is always supplied to the slurry inlet through the feed pipe F1 by the pump P. 1a is supplied to the slurry storage tank 1, while the slurry storage tank 1 is provided with an overflow portion 1b, and the overflowed slurry is returned to the slurry supply tank 13 through the return path 13a. Therefore, the liquid level in the slurry reservoir 1 is always kept constant.
[0030]
Solid-liquid separation of the slurry S in the slurry storage tank 1 is started by operating the main rotation driving means 6 to rotate the drum 2 clockwise in the figure.
(a) Along with the rotation of the drum 2, the slurry S in the slurry storage tank 1 includes filtrate pipes 9a, 9a in the filtration chambers 3a, 3a on the front side in the rotation direction among the filtration chambers located in the slurry storage tank 1, and As a result of being sucked by a vacuum pump (not shown) through the automatic valve member 8 and being brought into a vacuum pressure state, cake C is picked up on the surface of the filter cloth 2b. While the cake C adhering to the filter cloth surface is moved as it is rotated in the clockwise direction of the drum 2, the filtration chambers 3, 3,... Are maintained in a vacuum pressure state, and thus further suction filtration is performed.
[0031]
(b) When the drum 2 is further rotated, the vacuum pressure is applied to the cake on the drum filter medium in the filtration chambers 3, 3,. The scraper 11 scrapes and discharges the cake C2 having a thickness corresponding to the separation distance on the surface C1 of the cake C while leaving the cake C2 on the surface of the filter cloth 2b.
[0032]
(c) By further rotation of the drum 2, the residual cake C2 on the filter cloth is immersed in the slurry S of the slurry storage tank 1. At this time, when one whole chamber of the filtration chamber 3b where the residual cake C2 is located is immersed in the slurry S, the automatic valve member 8 sends compressed air to the filtration chambers 3b and 3b through the filtrate pipes 9b and 9b. The residual cake C2 is blown back into the slurry S of the slurry storage tank 1 by this compressed air. The blown-back residual cake C3 is stirred by the slurry stirring means 12 and dispersed again in the slurry S.
Thereafter, returning to (a) , the same operation is repeated.
[0033]
Thus, in the first aspect, the vacuum pressure acts on the inside of the filter cloth even when the cake is discharged, so that the filtrate adhering to the filter cloth 2b has a suction force toward the filtration chambers 3, 3,. In order to act, the filtrate is not reabsorbed by the cake C due to capillary action, and the filtrate adhering in the filtrate pipe 9 is not blown back to the cake C. Therefore, the moisture content of the discharged cake is reduced. Compared to the conventional method, it is reduced by 2-3%.
[0034]
In addition, as a separation distance of the scraper 11, it is preferable to set it as about 10 to 20% of cake thickness.
[0035]
Further, in the first mode, each time the drum 2 is rotated, the residual cake C2 is slurried by compressed air from the inside of the filter cloth 2b while the residual cake C2 is immersed in the slurry S in the step (c). Since the blowback is performed in the slurry in the storage tank 1, clogging of the filter cloth 2b is suppressed. Therefore, long-term continuous operation is possible.
[0036]
<Second aspect>
FIG. 3 shows a rotary cylindrical vacuum filter (hereinafter, referred to as a second embodiment) to which the invention according to claim 2 is applied. The apparatus configuration is based on the first aspect, and further, a slurry spray for projecting slurry onto the filter cloth surface 2b between the scraper 11 and the liquid surface S1 of the slurry storage tank 1 in the rotation direction of the drum 2. A pipe 14 is provided. The slurry spray pipe 14 is connected to a second feed pipe F2 branched from the first feed pipe F1. Therefore, a part of the slurry supplied from the slurry supply tank 13 to the slurry storage tank 1 is supplied to the slurry spray pipe 14 through the second feed pipe F2. In particular, in the first aspect, the automatic valve member is configured to maintain the vacuum pressure state for the filtration chamber after the cake is discharged and before being immersed in the slurry S in the slurry storage tank 1. However, in the second aspect, an automatic valve member (not shown) is configured to introduce atmospheric air into the filtration chamber 3c to be in an atmospheric pressure state.
[0037]
Next, the operation configuration will be described. In the second aspect, basically in the same manner as in the first aspect, (a) cake formation on the filter cloth, (b) cake scraping, (c) in the slurry as the drum rotates. In addition to this, the cake C2 remaining on the filter cloth 2b in the step (b) is immersed in the slurry S of the slurry storage tank 1 in the step (c). In the moving process, the inside of the filtration chamber 3c where the residual cake C2 is located is brought to atmospheric pressure by a vacuum pump (not shown) through an automatic valve member (not shown) and the filtrate pipe 9c, and then the slurry spray pipe 14 Further, the slurry is projected onto the residual cake C2 and washed off from the filter cloth 2b. Thereafter, the step (c) is performed, and the residual cake C4 that is not washed off from the filter cloth 2b by the projection of the slurry is blown back into the slurry S of the slurry storage tank 1.
[0038]
As described above, in the second aspect, in addition to the blowback of the residual cake in the slurry in the step (c) of the first aspect, the cake of the residual cake C2 is removed by the slurry after the cake is scraped in the step (b) . Since washing off and filter cloth washing are performed, the effect of preventing clogging is further improved. Therefore, the apparatus according to the second aspect can be continuously operated for a long time. Specifically, the continuous operation period of the conventional apparatus is 2 to 3 months, whereas the continuous operation period of the apparatus according to the second aspect is about 6 months.
[0039]
According to the first and second aspects described above, it is preferable to follow the third aspect described below when the moisture content of the cake is high due to fine crystals or other causes.
[0040]
<Third Aspect>
FIG. 4 shows a rotary cylindrical vacuum filter (hereinafter referred to as a third aspect) to which the solid-liquid separation method according to claim 3 is applied. The apparatus structure is based on the first aspect described above, and is further spaced above the drum 2 and surrounds the surface of the filter cloth 2b from the front side of the slurry storage tank 1 to the position before the scraper 11 in the drum rotation direction, A steam retaining wall 15 having a steam supply port 15a at the top is provided.
[0041]
In the third embodiment, as in the first embodiment, (a) cake formation on the filter cloth, (b) cake scraping, (c) in the slurry as the drum 2 rotates. While the residual cake is blown back, steam from a steam supply source (not shown) is supplied into the steam retaining wall 15 through the steam supply port 15a. The slurry V contained in the cake C on the filter cloth 2b is warmed by the steam V supplied into the retaining wall 15, and the viscosity is lowered (specifically, reduced by 3 to 6%), which is more effective. Suction filtration is performed. As a result, the moisture content of the discharged cake C1 decreases. The steam retaining wall 15 shown in FIG. 4 is provided so as to substantially surround the surface of the filter cloth 2b from the front side of the slurry storage tank 1 to the position in front of the scraper 11 in the drum rotation direction, but it is not necessary to be limited to this. Can be provided at an appropriate position.
[0042]
<Other aspects>
In the rotary cylindrical vacuum filter described in the first to third embodiments, as shown in FIG. 6, a washing water spray faces the outer surface of the filter cloth 2 b that rotates and moves from the slurry storage tank 1 as necessary. Pipes 10 and 10 may be provided. In this case, after the cake is formed on the drum filter medium in the step (a) , and before the cake is scraped off in the step (b) , the cake on the drum filter medium is washed. Washing water is projected from the water spray pipe 10 and washing is performed, and the washing water is sucked and filtered through the filtrate pipes 9, 9... Discharged.
[0043]
Further, when the cleaning liquid spray pipe 10 is provided as described above, it is preferable to supply warm water as cleaning water. The temperature of the hot water is preferably 35 to 80 ° C. In this temperature range, the washing water that has permeated the cake and the slurry solvent in the cake are easily sucked and filtered.
[0044]
On the other hand, as described above, the present invention basically has a configuration in which clogging hardly occurs. However, it is necessary to clean the filter cloth surface periodically or when clogging occurs.
[0045]
In this case, as shown in FIG. 6, when the clogging occurs when the high pressure washing water spray pipe 16 is provided facing the filter cloth 2b surface between the washing water spray pipe 10 and the slurry storage tank 1 in the drum rotation direction. Or it is preferable to wash | clean the filter cloth 2b surface regularly.
[0046]
When performing high-pressure washing, first, the solid-liquid separation of the slurry is interrupted, and all the filtration chambers 3, 3. Thereafter, the cake clogged in the filter cloth 2b is washed and removed by projecting high-pressure washing water from the high-pressure washing spray pipe 16 onto the surface of the filter cloth 2b while rotating the drum 2.
[0047]
Although FIG. 6 shows an example based on the first aspect, it goes without saying that the second and third aspects may be used as a basis.
[0048]
Hereinafter, the effects of the present invention will be clarified by showing examples.
<Example>
Using a rotary cylindrical vacuum filter testing machine according to the present invention, and a conventional rotary cylindrical vacuum filter, horizontal belt vacuum filter, and vertical centrifuge, gypsum from flue gas desulfurization slurry is obtained. The separation equipment was designed and its performance comparison experiment was conducted. The equipment design conditions are shown below.
Design conditions Processing volume: 20 tons / hr (water 0% standard)
Slurry concentration: 20 wt%
Average particle size of separated crystals: 50 to 100 μm
Slurry temperature: normal temperature to normal temperature + 20 ° C
Moisture content of cake: 10wt% or less
Chlorine content: 100 ppm or less Note that only the conventional rotary cylindrical vacuum filter cannot be designed so that the moisture content of the discharged cake cannot be 10 wt%.
Table 1 shows the results of performance comparison experiments under the above design conditions.
[0049]
[Table 1]

[0050]
As is apparent from Table 1, it is impossible for the conventional rotary cylindrical vacuum filter to reduce the moisture content of the cake to 10% or less, but this is possible with the rotary cylindrical vacuum filter of the present invention. Furthermore, the installation area of the equipment using the rotary cylindrical vacuum filter of the present invention may be 42.4-35.0% of the equipment using the horizontal belt type vacuum filter and the vertical centrifuge. Space saving can be achieved. The rotary cylindrical vacuum filter of the present invention has an operating power amount that is slightly higher than that of the conventional rotary cylindrical vacuum filter, but is approximately 74% that of the horizontal belt vacuum filter. About 35% of the machine can be used, and running costs can be reduced.
[0051]
In this example, the case where gypsum was separated from the flue gas desulfurization slurry was shown, but the present invention is not limited to this, and for example, the same results can be obtained even when used for the production of bisphenol, terephthalic acid and the like. This is easily understood by those skilled in the art without needing to show examples.
[0052]
【The invention's effect】
As described above, according to the present invention, a cake having a low water content can be obtained, and there are advantages such as reduction in apparatus cost, apparatus running cost, and apparatus installation space.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view thereof.
FIG. 3 is a longitudinal sectional view showing a second embodiment of the present invention.
FIG. 4 is a longitudinal sectional view showing a third aspect of the present invention.
FIG. 5 is a longitudinal sectional view showing a similar example.
FIG. 6 is a longitudinal sectional view showing another aspect of the present invention.
FIG. 7 is a longitudinal sectional view showing an outline of a conventional rotary cylindrical vacuum filter.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Slurry storage tank, 2 ... Drum, 3 ... Filtration chamber, 12 ... Slurry stirring means, 13 Slurry supply tank, S ... Slurry, C ... Cake.

Claims (6)

A slurry storage tank with an open top, a drum filter medium in which a filter cloth is stretched on the outer peripheral surface of a cylindrical drum via a filter chamber , and means for applying vacuum pressure and pressure to the filter chamber of the drum filter medium The drum filter medium uses a rotating cylindrical vacuum filter disposed so as to rotate in a state where a part of the drum filter medium is immersed in the slurry in the slurry storage tank.
In accordance with the rotation of the drum filter medium, the following steps (a) to (c) are performed every rotation.
(a) A cake forming step of forming a cake on the drum filter medium by applying a vacuum pressure to the inside of the drum filter medium located in the slurry storage tank.
(b) While a vacuum pressure is applied to the cake on the drum filter medium, a cake having a predetermined thickness is removed from the cake surface so that a part of the cake remains on the drum filter medium. Scraping process.
(c) After the residual cake on the drum filter medium is immersed in the slurry in the slurry storage tank , and the entire filtration chamber where the residual cake is located is immersed in the slurry, the entire cake is immersed in the slurry. A step of pressurizing the inside of the filtration chamber and blowing back the residual cake on the drum filter medium into the slurry of the slurry storage tank . The drum to which the residual cake adheres after the cake is scraped off in the step (b) and before the residual cake is immersed in the slurry in the slurry storage tank in the step (c) . The solid-liquid separation method according to claim 1, wherein the inside of the filter medium is set to atmospheric pressure, and a slurry substantially the same as the slurry in the slurry storage tank is projected onto the residual cake on the drum filter medium. After the cake is formed on the drum filter medium in the step (a) and before the cake is scraped off in the step (b) , steam is supplied to the cake on the drum filter medium. The solid-liquid separation method according to claim 1 or 2. After the cake is formed on the drum filter medium in the step (a) and before the cake is scraped off in the step (b) , hot water is supplied to the cake on the drum filter medium. The solid-liquid separation method according to any one of claims 1 to 3, wherein the cake is washed with warm water. The solid-liquid separation according to any one of claims 1 to 4, wherein a liquid content of the cake scraped off in the step (b) is 8 to 10 wt% with respect to a solid in the cake. Method. A slurry storage tank with an open top, a drum filter medium in which a filter cloth is stretched on the outer peripheral surface of a cylindrical drum via a filter chamber , and means for applying vacuum pressure and pressure to the filter chamber of the drum filter medium The drum filter medium is a rotary cylindrical vacuum filter arranged so as to rotate in a state where a part of the drum filter medium is immersed in the slurry of the slurry storage tank.
As the drum filter medium rotates,
Means for forming a cake on the drum filter medium by applying a vacuum pressure to the inside of the drum filter medium located in the slurry storage tank;
Means for scraping a cake of a predetermined thickness from the cake surface so that a part of the cake remains on the drum filter medium while a vacuum pressure is applied to the cake on the drum filter medium inside the drum filter medium When,
After the residual cake on the drum filter medium is immersed in the slurry of the slurry storage tank , and the entire filtration chamber in which the residual cake is located is immersed in the slurry, the entire filtration chamber is immersed in the slurry. A rotary cylindrical vacuum filter provided with means for pressurizing and blowing back the residual cake on the drum filter medium into the slurry of the slurry storage tank .

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