KR101047972B1 - Cleaning Method of Vacuum Filtration Device and Vacuum Filtration Device - Google Patents

Abstract

An object of this invention is to remove the crystal | crystallization which adheres to a filter cloth and a grid board at a suitable timing smoothly, and to prevent clogging and blockage of a filtrate flow space reliably. As a cleaning method of a vacuum filtration apparatus, a tray cleaning liquid is supplied into a vacuum tray based on the vacuum pressure of the vacuum line 20 in the vacuum trays 16A-16E, and this vacuum tray is immersed and wash | cleans a vacuum tray.

Description

Cleaning method of vacuum filtration apparatus and vacuum filtration apparatus {VACUUM FILTERATION APPARATUS AND CLEANING METHOD USING THE SAME}

1 is a schematic block diagram showing an embodiment of the present invention.

FIG. 2 is a side view illustrating the apparatus body of FIG. 1. FIG.

3 is a partially enlarged cross-sectional view illustrating the vacuum tray of FIG. 2.

<Description of the symbols for the main parts of the drawings>

10: device body

11: filter cloth

16: vacuum tray

16I: grid plate

20: vacuum line

26: cleaning liquid supply means

27A to 27C: vacuum pressure measuring means

30: vacuum suction device

F: driving direction

S: slurry

The present invention relates to a cleaning method of a vacuum filtration device and a vacuum filtration device, each of which is configured to vacuum-suck and filter a slurry supplied on a filter cloth that is capable of traveling substantially horizontally by a vacuum tray provided under the filter cloth.

A purification operation is performed in which the mother liquor is separated from the slurry by filtration to extract the crystal component or the crystal component is purified. For example, when a crystalline component of an organic substance dissolved in a solvent is separated from a mother liquid and extracted as crystals, it is conventionally performed by a centrifuge, a continuous filter, a horizontal tray filter, or the like. In that case, the liquid containing a crystalline component is a saturated solution, and at the time of operation start, the filter cloth and the upper surface part (grid plate) of the vacuum tray which contact this are generally in the normal temperature state lower than operation temperature, and also a slurry The liquid is cooled in the process of contacting and passing through the cake layer or the filter cloth due to the fact that it has a large heat capacity that influences the thermal conditions of the crystals. Crystals adhere to the open holes or the corners of the plate, causing clogging and blockage of the filtrate flow space. This phenomenon occurs either in a batch or in a continuous mode, and the filtration ability is significantly lowered. As a result, only low-purity crystals can be obtained, and the yield is further reduced. Therefore, it is necessary to periodically wash the filter cloth and the grid plate, and as a result, the operation rate is lowered. And such a problem arises also when the above-mentioned mechanical filtration operation | movement is performed in refinement | purification of the crystal | crystallization of a slurry of a process system, or a solid solution.

In addition, when the temperature difference between the melting temperature of the crystal | crystallization of the organic substance melt | dissolved in the solvent, and the crystal precipitation temperature is less than 10 degreeC, or when dissolving the crystalline component whose melting temperature is 30 degrees C or less from a mother liquid, and extracting it as a crystal | crystallization, for example, following patent Although the said problem can be solved by the special filter medium structure shown by the document 1, there exists a problem that the apparatus becomes more complicated about the crystal component in temperature conditions other than the above, and equipment cost increases.

As a means for solving the above problems, for example, a liquid containing a crystalline component is separated by a crystalline component and a mother liquid through the filter cloth by a vacuum tray provided on the back portion of the filter cloth as shown in Patent Document 2 below. In the cleaning method of the vacuum filtration apparatus, the vacuum cleaning apparatus includes a tray cleaning liquid supplied to a rear portion of the filter cloth to fill it, to dissolve and recover the crystals attached to the back portion of the filter cloth. Another vacuum tray is operated as a cake formation, a cake washing, and a liquid removal solution, and the method of cleaning is performed by performing the same operation for each vacuum tray.

Patent Document 1-Japanese Patent Application Laid-Open No. 2-126902

Patent Document 2-Patent No. 3497206

However, as described above, when the crystalline component of the organic substance dissolved in the solvent is separated from the mother liquor and extracted as crystals, the vacuum filtration device is configured such that the entirety of the plurality of vacuum trays are housed in a sealed chamber and shut off from the outside. In many cases, it was difficult to accurately grasp the volume adhesion state of the crystal | crystallization in the said grid board and a filter cloth by the said sealed chamber. For this reason, the timing which supplies a tray cleaning liquid to the back part of the said filter cloth was made to be when the predetermined period of use had passed. In this case, however, even when the volume is different at the same timing due to variations in the operation conditions of the vacuum filtration device, for example, the cleaning is performed even if the filter cloth and the grid plate are not yet in a state where cleaning is required. Despite being in a necessary state, cleaning has not yet been performed, and there is a problem that it is difficult to perform the cleaning at an appropriate timing. In addition, if the timing of cleaning is delayed, the filtration capacity of the vacuum filtration device may be lowered, resulting in poor cleaning or poor liquid removal, resulting in poor product quality. If the timing of cleaning is early, the cleaning liquid is wasted.

The present invention has been made under such a background, and it is possible to smoothly remove the crystals attached to the filter cloth or the grid plate at an appropriate timing, thereby providing a vacuum filtration device that can reliably prevent clogging or blockage of the filtrate flow space. It is an object to provide a cleaning method and a vacuum filtration device.

In order to solve the above problems and to achieve the above object, the cleaning method of the vacuum filtration device of the present invention is provided with a vacuum tray connected to the vacuum suction device through a vacuum line under the filter cloth installed to be able to run approximately horizontally on the apparatus main body, A cleaning method for a vacuum filtration device comprising a filter for vacuuming a slurry supplied on the filter cloth by vacuum suction through the filter cloth by the vacuum tray, the tray cleaning liquid in the vacuum tray based on the vacuum pressure of the vacuum line. Is supplied, the tray cleaning liquid is immersed in the vacuum tray, and the vacuum tray is washed.

In addition, the vacuum filtration device of the present invention is provided with a plurality of vacuum trays connected to the vacuum suction device through a vacuum line under the filter cloth provided to be able to travel substantially horizontally in the apparatus main body in the traveling direction of the filter cloth, and supplied on the filter cloth. A vacuum filtration device configured to filter a slurry by vacuum suction through the filter cloth by the vacuum tray, wherein the vacuum pressure in the vacuum line in one or more vacuum trays of the plurality of vacuum trays is measured. And a cleaning liquid supplying means for supplying a tray cleaning liquid to the vacuum tray, wherein the cleaning liquid supplying means is provided to the vacuum tray by the cleaning liquid supplying means based on the vacuum pressure measured by the vacuum pressure measuring means. Supply the tray cleaning liquid and By immersing the tray, the washing liquid within the tray, characterized by washing the vacuum tray.

According to these inventions, since the timing of supplying the cleaning liquid to the vacuum tray is determined based on the vacuum pressure of the vacuum line, the crystalline component of the slurry is deposited on the grid plate or the like of the vacuum tray regardless of the fluctuations in the operating conditions of the vacuum filtration apparatus. (Iii) It is possible to accurately grasp the adhered state, and the grid plate or the like can be cleaned at an appropriate timing. In other words, if the amount of deposition of crystalline components on the grid plate or the like is large, the vacuum pressure is high, and if the amount of adhesion is small, the vacuum pressure is low, so that the cleaning is performed when the vacuum pressure exceeds a predetermined value, for example, -40 kPaG. Can be. Thereby, the fall of the product quality and waste of a washing | cleaning liquid by the generation | occurrence | production of a washing | cleaning defect and a liquid removal defect can be prevented.

Here, it is preferable that a plurality of the vacuum trays are provided in the traveling direction of the filter cloth, and the vacuum trays are cleaned based on the vacuum pressure of the vacuum line in one or more vacuum trays of the plurality of vacuum trays. Moreover, it is preferable to measure the vacuum pressure regarding each of the said vacuum lines in a plurality of said vacuum trays, and to wash only the said vacuum tray which the said vacuum pressure exceeded the predetermined value.

In these cases, it is possible to clean only the vacuum tray which requires cleaning, to prevent the waste of the cleaning liquid, and to achieve high-efficiency cleaning.

In addition, it is preferable that the tray cleaning liquid is supplied into the vacuum tray and washed while overflowing from the vacuum tray to another vacuum tray adjacent to the vacuum tray.

That is, when the tray cleaning liquid does not overflow from the vacuum tray and remains in the vacuum tray with a liquid level of a predetermined height, the tray cleaning liquid located on the liquid surface may be cooled in the process of cleaning to cause a temperature drop. For this reason, the crystal component melt | dissolved in the tray washing | cleaning liquid located in the said liquid surface may re-precipitate on the wall surface of the vacuum tray which contacts this liquid surface.

However, when the tray cleaning liquid is overflowed from the vacuum tray as described above, the liquid surface is not formed, and the dissolved crystal component contained in the tray cleaning liquid on the wall surface of the vacuum tray can be prevented from being reprecipitated. The temperature drop of the tray cleaning liquid located within can be suppressed, and it is possible to promote dissolution of the crystal component adhered to the grid plate or the like into the tray cleaning liquid, thereby preventing the lack of cleaning.

In addition, by placing the height of the tray cleaning liquid overflowed from the vacuum tray near the lower surface of the filter cloth, not only the grid plate but also the lower surface of the filter cloth can be immersed in the tray cleaning liquid, thereby determining the volume of the slurry attached to the lower surface of the filter cloth. The component can also be washed and removed.

Moreover, it is preferable to maintain the temperature of the said tray washing | cleaning liquid above the temperature at which recrystallization of the said crystal component is performed.

Further, the plurality of vacuum trays are used for cake formation, cake cleaning, and dewatering, and the vacuum pressure measuring means and the cleaning liquid supplying means are provided at least in the vacuum line of the vacuum tray for dewatering. It is preferable.

In this case, the amount of mother liquor contained in the slurry itself is small in the vacuum tray for dehydration, and since the amount of gas to be sucked is large, the temperature of the filtrate decreases, and the crystal component is particularly easy to precipitate in the grid plate or the like. Since the vacuum tray which is easy to produce is equipped with the vacuum pressure measuring means and the washing | cleaning liquid supply means, the crystal component precipitated in the vacuum filtration apparatus can be dissolved and removed effectively.

In particular, the vacuum tray for the liquid removal is constituted by a plurality of vacuum trays, and the vacuum pressure measuring means and the cleaning liquid supplying means are provided in the vacuum lines of the vacuum trays for the liquid removal, for example, the one vacuum. While the tray is being washed, the liquid can be continuously degreased with another vacuum tray, so that the washing can be performed without stopping suction filtration of the filtrate by the vacuum filtration device, thereby achieving highly efficient cleaning. have.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

The vacuum filtration apparatus of this embodiment is provided with the apparatus main body 10, the vacuum line 20, the vacuum suction apparatus 30, and the room temperature control line 50 schematically as shown in FIG. Hereinafter, the contents of the components 10, 20, 30, and 50 will be described in detail.

First, in the apparatus main body 10, as shown in FIG. 2, the endless belt-shaped filter cloth 11 is wound between several roll 12, and the upper part of this filter cloth 11 is arrange | positioned so that it may extend in a horizontal direction. 11 A of filtered filtration parts. And the roll 12A by which the filter cloth 11 is wound by the one end side (right side in FIG. 1 and FIG. 2) of this filter part 11A is connected to the drive apparatus which is not shown in figure. By the driving device, the roll 12A is rotationally driven in the clockwise direction in the figure, and the filter cloth 11 is also driven to rotate continuously along the circumference between the rolls 12. Thereby, the filter part 11A of the filter cloth 11 runs continuously in the travel direction shown by the arrow F in a figure.                     

Underneath the filtration part 11A, the vacuum tray 16 connected to the vacuum suction apparatus 30 is plural toward the running direction F of the said filtration part 11A from about immediately below the slurry supply apparatus 13 mentioned later. (Five in the example of the city) are provided. Of these vacuum trays 16, the vacuum tray 16A disposed at the rear end of the traveling direction F and located just below the slurry supply device 13 is used for cake formation (hereinafter, cake formation). Tray (16A). In addition, the vacuum tray 16B which is adjacent to the cake forming tray 16A and located just below the cake cleaning apparatus 21 which will be described later is used for cake cleaning (hereinafter, the cake cleaning tray 16B). ). In addition, the vacuum trays 16C, 16D, and 16E which are adjacent to the cake washing tray 16B and are provided in the plurality in the traveling direction F are used for the liquid removal (hereinafter, in the rear of the traveling direction F). The vacuum trays 16C to 16E that are sequentially installed toward the front are referred to as a first stripping liquid 16C, a second stripping liquid 16D, and a third stripping liquid 16E).

The plurality of vacuum trays 16 are connected to each other adjacent to the traveling direction F. Among the vacuum trays, the vacuum tray 16 located at the rear end of the traveling direction F, that is, the cake forming tray 16A, is attached to the frame 10A of the apparatus main body 10 as shown in FIG. It is connected to drive cylinders 18, such as an air cylinder, which were made extensible toward the said running direction F. As shown in FIG. As a result, all of the vacuum trays 16 are reciprocally movable integrally in a predetermined stroke in the traveling direction F, that is, they can move forward and backward in this traveling direction F. FIG.

Moreover, as shown in FIG. 2, the apparatus main body 10 has a pair of rails 22 which were provided in the several vacuum trays 16 so that it may extend in the said traveling direction F below the width direction both ends below it. A plurality of rotatable support wheels 19 which contact and support the vacuum tray 16 are provided at intervals in the width direction of the filter cloth 11. The vacuum tray 16 is capable of moving back and forth on these freely rotating support wheels 19, on the contrary, the support wheels 19 are driven in accordance with the retraction of the vacuum tray 16 by the drive cylinder 18. Rotationally. Here, the support wheels 19 are the same shape and same size as each other rotatably attached around a horizontal rotation axis extending in the width direction through a bracket or the like installed upwardly on the frame 10A of the apparatus main body 10, respectively. The outer surface of the vacuum tray 16 extends in the traveling direction F along both edges in the width direction of the lower surface portion of the vacuum tray 16. It is arranged to form two rows parallel to each other. The support wheels 19 in each row are arranged at equal intervals in the travel direction F, and the support wheels 19 between the two rows are paired in the width direction, and the support wheels 19 which constitute these pairs are provided. 19) They are arrange | positioned at the same position in the up-down direction mutually, and the same position also in the travel direction F.

The slurry S is supplied on the filter cloth 11 to the other end side (left side in FIGS. 1 and 2) of the filter part 11 of the filter cloth 11, that is, the upper side of the rear side with respect to the traveling direction F. The slurry supply apparatus 13 is installed. While the slurry S supplied from the supply device 13 onto the filter cloth 11 is moved in the traveling direction F at the same time as the running of the filter portion 11A, the filter cloth 11 by each vacuum tray 16. Vacuum suction through the filtration is to be. And the cake washing | cleaning apparatus 21 which supplies the cake washing | cleaning liquid L toward the filter cloth 11 above the slurry supply apparatus 13 of the filtering part 11A is provided, and the slurry The cake cleaning liquid L is supplied to the cake layer in which S is filtered by the suction. The roll 12A for driving the filter cloth 11 is provided with a knife 14 for peeling off the filter cake 11 by scraping off the dewatering cake from which the dewatering is completed. Moreover, the slurry S is scraped by this knife 14 at the one end side (right side in FIG. 1) of the filtration part 11A of the filter cloth 11, ie, the lower side of the front side with respect to the said running direction F. The filter cloth cleaning device 15 for washing the filter cloth 11 after being dropped is provided.

In this embodiment, the apparatus main body 10, the slurry supply apparatus 13, and the cake cleaning apparatus 21 are accommodated in the sealed chamber R as shown in FIG.

In addition, the plurality of vacuum trays 16 respectively extend along the surface of the filtering portion 11A, as shown in FIG. 3, and the flat portion 16F whose upper surface is in close contact with the lower surface of the filtering portion 11A. And wall portions 16G and 16G extended so as to extend toward both outer sides of the width direction as they face upward at both ends in the width direction of the flat portion 16F. The flat part 16F is a laminated body in which the plate-shaped body 16H and the grid board 16I in which the many through-hole 16J was formed in the surface were laminated | stacked in this order. The lower surface of the filtering portion 11A is in close contact with the front surface side of the grid plate 16I, while the vacuum line 20 in communication with the vacuum suction device 30 is connected to the rear surface side.                     

As shown in FIG. 1, the vacuum suction apparatus 30 collects the filtrate obtained from each vacuum tray 16, and gas-liquid separation tank 31-33 which carries out the gas-liquid separation of this filtrate, and the said gas-liquid separation tank 31 And a vacuum pump 34 for exerting a vacuum suction force on the slurry S on the filtration part 11A through these 31 to 33, gas-liquid separation tanks 31 to 33, and a vacuum pump 34. ) And a cooler 35 configured to cool the gas discharged from the gas-liquid separation tanks 31 to 33 before passing through the vacuum pump 34.

The gas-liquid separation tanks 31 to 33 include a first gas-liquid separation tank 31 communicated with the cake forming tray 16A, a second gas-liquid separation tank 32 communicated with the cake cleaning tray 16B, and The third gas-liquid separation tank 33 communicated with the 1st-3rd liquid removal trays 16C, 16D, and 16E is provided. And each gas-liquid separation tank 31-33 is the liquid level measuring device 36-38 which measures the quantity of the filtrate collect | recovered in the said separation tank 31-33, respectively, and this filtrate is a gas-liquid separation tank 31-33. Automatic valves SV1 to 41 that open and close the outlet of the filtrate in the gas-liquid separation tanks 31 to 33 based on the filtrate pumps 39 to 41 to be discharged from 33 and the measurement results of the liquid level measuring devices 36 to 38. SV3). In addition, a first temperature measuring device 42 capable of measuring the temperature of the gas is provided between the gas-liquid separation tanks 31 to 33 and the cooler 35. The opening degree of the control valve CV1 is operated based on the measurement result of the 1st temperature measuring device 42, and the cooler 35 is controlled, and it is possible to control the temperature of the said gas by this.

In addition, the vacuum filtration apparatus of the present embodiment communicates with the vacuum pump 34 and at the same time the gas cooled by the cooler 35 is supplied to control the temperature of the gas, and then the gas is cooled into the sealed chamber R. It is provided with the room temperature control line 50 which became controllable by supplying the temperature in this sealed chamber R. The room temperature control line 50 includes a first heater 51 for heating the gas supplied from the vacuum pump 34, a second temperature measuring device 52 for measuring a temperature in the closed chamber R, A flow rate measuring instrument 53 is provided for measuring the flow rate inside the closed chamber R of the gas heated by the one heater 51. In addition, the control valve CV2 for adjusting the first heater 51 based on the measurement result of the second temperature measuring device 52 and the supply to the closed chamber R based on the measurement result of the flow rate measuring device 53. The control valve CV3 which adjusts the flow volume of the said gas is provided. The gas whose temperature and flow rate are adjusted by the above flows into the closed chamber R through the automatic valve SV4.

Here, the vacuum line 20 is a first vacuum line 20A connecting the lower surface of the cake forming tray 16A and the first gas-liquid separation tank 31 as shown in FIG. 1, and a cake cleaning tray. 2nd vacuum line 20B which connects the lower surface of 16B and the 2nd gas-liquid separation tank 32, the 1st-3rd liquid removal trays 16C, 16D, and 16E, and the 3rd gas-liquid separation tank 33 The 3rd vacuum line 20C which connects is provided. The first to third header lines 22 to 24 are provided in the first to third vacuum lines 20A, 20B, and 20C, respectively. The interior of the third header tube 24 connected to the first to third liquid removal trays 16C to 16E is divided into approximately three equal parts by two diaphragms 25, and the first to third spaces are divided into first to third spaces. The third liquid removal trays 16C to 16E are configured to communicate with each other. In addition, the part which communicated with the 1st liquid removal tray 16C among each space partitioned in the said 3rd header tube 24 for the convenience of description below is called "3rd header tube 24A", 2 The part in communication with the liquid removal tray 16D is called "third header tube 24B", and the part in communication with the third liquid removal tray 16E is called "third header tube 24C". .

By the way, in this embodiment, the crystalline component of the slurry S in these trays 16C-16E, respectively, between the 1st-3rd liquid removal trays 16C-16E and the said partitioned 3rd header pipe 24A-24C, respectively. The tray cleaning liquid supply means 26 which supplies the tray cleaning liquid which can melt | dissolve is provided. In addition, automatic valves SV5 to SV7 are provided between the tray cleaning liquid supply means 26 and the third header pipes 24A to 24C. Further, the partitioned third header tubes 24A to 24C each have a lower surface of the filtration unit 11A facing the upper surface of the first to third liquid removal trays 16C to 16E, and the vacuum suction device 30. First to third vacuum pressure measuring means 27A to 27C for measuring the vacuum pressure of the filter are provided.

As shown in Fig. 1, the tray cleaning liquid supply means 26 includes automatic valves SV8, SV9, SV10 and first to third dewatering trays connected to the first to third dewatering trays 16C to 16E. Based on the measurement result of the 3rd temperature measuring device 26A which measures the temperature of the tray cleaning liquid before supplied to (16C-16E), the 2nd heater 26B which heats a tray cleaning liquid, and the 3rd temperature measuring device 26A. Control valve CV4 for adjusting the flow rate of the heating medium supplied to the second heater 26B, and the tray cleaning liquid to the first to third dehydration trays 16C to 16E through automatic valves SV8 to SV10. It is equipped with the pump which is not shown in figure to supply. By this structure, the temperature of the tray cleaning liquid supplied to each of the first to third liquid removal trays 16C to 16E through the respective automatic valves SV8 to SV10 is controlled, and is 5 to 5 degrees higher than the temperature at which crystallization of the mother liquid is performed. It is controlled to increase by about 10 ° C.                     

In this embodiment, a control unit (not shown) is provided, and the control unit includes vacuum pressure measuring means 27A to 27C, automatic valves SV5 to SV7 and SV8 to SV10, and tray cleaning liquid supply means 26. The pump is connected. The output signal of the vacuum pressure measuring means 27A to 27C is transmitted to the pump and the automatic valves SV5 to SV7 and SV8 to SV10 via the control unit. That is, when the vacuum pressure measured by the vacuum pressure measuring means 27A to 27C is smaller than the predetermined value (for example, -40 kPaG), the automatic valves SV8 to SV10 are closed and the automatic valves SV5 to SV7 are opened. The filtrate recovered from the slurry S through the filtering section 11A is transferred to the third header tube 24 without supplying the tray cleaning liquid to the first to third dehydration trays 16C to 16E. On the other hand, when the vacuum pressure exceeds a predetermined value, the automatic valves SV8 to SV10 are opened, and the automatic valves SV5 to SV7 are closed to the third header tube 24 of the filtrate. Is stopped, and the tray cleaning liquid is supplied to the first to third stripping trays 16C to 16E.

The automatic valves SV5 to SV7 and SV8 to SV10 are respectively opened and closed based on the measurement results of the respective vacuum pressure measuring means 27A to 27C, and each of the first to third liquid removal trays 16C to 16E is opened. It is intended to be washed separately. That is, the automatic valves SV5 and SV8 open and close based on the measurement result of the first vacuum pressure measuring means 28A, and the automatic valves SV6 and SV9 based on the measurement results of the second vacuum pressure measuring means 28B. Is opened and closed, and the automatic valves SV7 and SV10 are opened and closed based on the measurement result of the third vacuum pressure measuring means 28C.

Next, the usage method of the vacuum filtration apparatus comprised as mentioned above is demonstrated.

First, in the normal operation, the slurry S is supplied to the filter portion 11A positioned on the cake forming tray 16A by the slurry supply means 13 as in the prior art, and the slurry acts on the tray 16A. The filtrate of slurry S is suction-filtered by pneumatic pressure, and a cake layer is formed. Thereafter, the cake layer is positioned on the washing tray 16B by the filtering portion 11A, and the cake washing liquid L is supplied by the cake washing apparatus 21, whereby the cake layer is washed. In addition, this cake layer is liquefied by being sequentially placed in the 1st-3rd liquid removal trays 16C-16E by the filter part 11A. At this time, the filtrate recovered by each vacuum tray 16 passes through the header tubes 22-24, respectively, and is led to gas-liquid separation tanks 31-33, respectively, and gas-liquid separation is carried out.

And the liquid surface position of the filtrate in each said gas-liquid separation tank 31-33 is continuously measured by the liquid level measuring devices 36-38. Based on the measurement result, the filtrate in the gas-liquid separation tanks 31-33 is sent toward arbitrary processes through the filtrate pumps 39-41 and automatic valves SV1-SV3. On the other hand, the gas discharged from the respective gas-liquid separation tanks 31 to 33 is thermally coagulated by passing through a cooler 35 because some of the solution is mixed, and then the second gas-liquid separation tank ( Return to 32). Accordingly, after the gas sucked by the vacuum pump 34 is dried, the gas is returned to the sealed chamber R through the room temperature control line 50. At this time, since the temperature of the gas must be maintained above the crystal precipitation temperature of the mother liquid, the temperature in the sealed chamber R is always detected by the second temperature measuring device 52, and the temperature measuring device 52 According to the output, the temperature of the gas is controlled by the first heater 51 and the control valve CV2 so as to be 5 to 20 ° C. higher than the temperature at which crystallization of the mother liquid is performed. Accordingly, the inside of the sealing chamber R is maintained at a constant temperature maintained at a predetermined temperature.

In addition, the temperature of the cake cleaning liquid L is always detected also by the fourth temperature measuring device (not shown) with respect to the cake cleaning liquid L, and also by the third heater (not shown) in accordance with the output of the temperature measuring instrument. It controls so that 5-10 degreeC may be higher than the temperature which crystallization of a mother liquid is performed. As a result, the temperature of the mother liquor and the filtrate can be maintained above the crystallization temperature, and the precipitation of the crystal can be prevented to allow stable operation for a long time.

However, as described above, even if the operation is continued while the means for preventing the precipitation of the crystal is continued, the lower surface of the filtering portion 11A and the grid plate 16I of the first to third liquid removal trays 16C to 16E are used. There is a fear that the crystalline component of the slurry (S) adheres in volume.

Hereinafter, the case where the crystalline component adheres to the 1st liquid removal tray 16C by volume is demonstrated. In this case, the vacuum pressure between the lower surface of the filter part 11A located in the 1st liquid removal tray 16C, and the vacuum suction apparatus 30 becomes high. And when the 1st vacuum pressure measuring means 27A provided in the 3rd header tube 24A detected that this vacuum pressure exceeded the predetermined value, the output signal from the said vacuum pressure measuring means 27A will drive the said control part. Via automatic valves SV8, SV5 and the pump. As a result, the automatic valve SV8 is opened, the automatic valve SV5 is closed, and the tray cleaning liquid is supplied to the tray 16C in a state in which suction filtration by the first desorption tray 16C is stopped. The tray cleaning liquid whose flow rate and temperature were controlled by the means 26 is supplied. Also in this case, the filtration suction by the other vacuum trays 16 (16A, 16B, 16D and 16E) is continuously performed.

The tray cleaning liquid guided to the first liquid removal tray 16C in this manner is a predetermined time while the grid plate 16I is flooded in this tray 16C so that the grid plate 16I is immersed and contacts the lower surface of the filtering section 11A. Continue the filtration operation. At this time, since the tray cleaning liquid is mechanically shaken in accordance with the reciprocating movement of each vacuum tray 16, cleaning is effectively performed. In particular, since the tray cleaning liquid overflows a small amount from the first degreasing tray 16C, the tray cleaning liquid containing the crystalline component is not cooled in contact with the wall surface of the tray 16C. The precipitation of the crystalline component is prevented. After the lapse of a predetermined time, the automatic valve SV8 is closed to stop the supply of the tray cleaning liquid, and the automatic valve SV5 is opened to recover the tray cleaning liquid as a filtrate.

In addition, when washing | cleaning by the 2nd liquid removal tray 16D, automatic valve SV6 is closed and automatic valve SV9 is opened. In addition, when washing | cleaning by the 3rd liquid removal tray 16E, washing | cleaning can be performed as mentioned above by closing automatic valve SV7 and opening automatic valve SV10.

As described above, according to the vacuum filtration apparatus according to the present embodiment, since the timing for supplying the tray cleaning liquid to the vacuum tray 16 is determined based on the vacuum pressure of the vacuum line 20, the operation conditions of the vacuum filtration apparatus, and the like. Irrespective of the variation, it is possible to accurately grasp the state of adhesion of the crystal component to the grid plate 16I and the like, and the grid plate 16I and the like can be cleaned at an appropriate timing. That is, when the deposition amount of the crystal component on the grid plate 16I or the like is large, the vacuum pressure becomes high, and when the deposition amount is small, the vacuum pressure becomes low. Therefore, when the vacuum pressure exceeds a predetermined value, for example, -40 kPaG, It can be cleaned. Thereby, the fall of the product quality and waste of a washing | cleaning liquid by the generation | occurrence | production of a washing | cleaning defect and a liquid removal defect can be prevented.

In addition, the vacuum pressure is measured for each of the vacuum lines 20 in the plurality of liquid removal trays 16C to 16E, and only the tray whose vacuum pressure exceeds a predetermined value is cleaned, so that waste of the cleaning liquid can be prevented. At the same time, high efficiency cleaning can be realized.

In addition, while performing the said washing | cleaning with respect to the 16 C of 1st dehydration trays, the other vacuum trays 16D and 16E are made to perform dehydration continuously, and the suction filtration of a filtrate by a vacuum filtration apparatus is not stopped. The above cleaning can be performed, and high efficiency cleaning can be realized. In addition, since the suction filtration by the vacuum filtration apparatus is continued while the grid plate 16I is immersed in the tray cleaning liquid, the tray cleaning liquid is mechanically shaken at this time, and the cleaning can be effectively performed.

In addition, since the tray cleaning liquid is supplied into the vacuum tray 16 to overflow from the tray 16, not only the grid plate 16I but also the lower surface of the filtration unit 11A can be immersed in the tray cleaning liquid. Both of the crystalline components attached to the elements 16I and 11A in volume can be satisfactorily dissolved and removed.

That is, when the tray cleaning liquid does not overflow from the vacuum tray 16 and is kept in the vacuum tray 16 with a liquid level of a predetermined height, the tray cleaning liquid located on the liquid surface is cooled in the process of cleaning. There is a risk of temperature drop. For this reason, the crystal component melt | dissolved in the tray washing | cleaning liquid located in the said liquid surface may re-precipitate on the wall surface of the vacuum tray 16 which contacts this liquid surface.

However, when the tray cleaning liquid is overflowed from the vacuum tray 16 as in this embodiment, the liquid surface is not formed, and the dissolved crystal component contained in the tray cleaning liquid is prevented from reprecipitation on the wall surface of the vacuum tray 16. At the same time, it is possible to suppress the temperature drop of the tray cleaning liquid located in the vacuum tray 16, and to promote dissolution in the tray cleaning liquid of the crystal component adhered to the grid plate 16I or the like. The lack of washing can be prevented.

In addition, by placing the height of the tray cleaning liquid overflowed from the vacuum tray 16 near the lower surface of the filtering portion 11A, not only the grid plate 16I but also the lower surface of the filtering portion 11A can be immersed in the tray cleaning liquid. The crystal component of the slurry S adhered to the lower surface of the filtering portion 11A can also be washed and removed. In particular, in the present embodiment, since the temperature of the tray cleaning liquid is kept above the temperature at which the crystal component is recrystallized, it becomes possible to further promote the dissolution of the crystal in the tray cleaning liquid.

In addition, in the first to third dehydration trays 16C to 16E, the amount of the mother liquid contained in the slurry S itself is small, and since the amount of gas to be sucked is large, the temperature of the filtrate decreases, and the grid plate 16I is used. The crystal component is particularly easy to precipitate on the back, but since the vacuum trays are easily provided with vacuum pressure measuring means 27A to 27C and the washing liquid supplying means 26, the crystal component precipitated in the vacuum filtration device is effectively dissolved. Can be removed In addition, in this embodiment, even when one of the plurality of liquid removal trays 16C to 16E is cleaned, the remaining vacuum liquid tray is continuously operated for the liquid removal, so that highly efficient cleaning can be reliably realized. have.

Moreover, the technical scope of this invention is not limited to the said Example, It is possible to add various changes in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, the vacuum line measuring means 26 and the cleaning liquid supply means 27A to 27B are respectively provided in the vacuum line 20C for each of the first to third liquid removing trays 16C to 16E. Although shown, it is not limited to this, The washing | cleaning liquid supply means 26 to the vacuum line 20 which connects the said vacuum tray and the vacuum suction apparatus 30 with respect to one or more of the said vacuum tray 16. And the vacuum pressure measuring means 27 are preferable. That is, for example, the cleaning liquid supply means 26 and the vacuum pressure measuring means 27 may be disposed only in any one of the first vacuum line 20A, the second vacuum line 20B, or the third vacuum line 20C. You may arrange in all of the 1st-3rd vacuum lines 20A, 20B, and 20C.

In addition, although the structure which supplies the tray cleaning liquid to the vacuum tray 16 automatically was shown in the said Example, the vacuum pressure measuring means 27A-27C is arrange | positioned outside the said closed chamber R, and the said vacuum pressure is changed. The tray cleaning liquid supplying means 26 etc. may be operated manually by an operator by visual confirmation.

The crystals attached to the filter cloth or grid plate can be smoothly removed at an appropriate timing, so that clogging and clogging of the filtrate flow space can be reliably prevented.

Claims (7)

The vacuum tray connected to the vacuum suction apparatus via the vacuum line is installed under the filter cloth installed so that the apparatus main body can run horizontally, and the slurry supplied on this filter cloth is filtered by vacuum suction through the said filter cloth by the said vacuum tray. In the cleaning method of the vacuum filtration device consisting of, The cleaning method of the vacuum filtration apparatus characterized by supplying a tray cleaning liquid to the said vacuum tray based on the vacuum pressure of the said vacuum line, immersing a tray cleaning liquid in the said vacuum tray, and washing this vacuum tray. The vacuum tray of claim 1, wherein a plurality of the vacuum trays are provided in a traveling direction of the filter cloth, and the vacuum trays are cleaned on the basis of the vacuum pressure of the vacuum line in one or more vacuum trays of the plurality of vacuum trays. The cleaning method of a vacuum filtration apparatus. The vacuum filtration apparatus according to claim 1 or 2, wherein the vacuum pressure of each of the vacuum lines is measured in a plurality of vacuum trays, and only the vacuum tray whose vacuum pressure exceeds a predetermined value is cleaned. Cleaning method. The cleaning method of a vacuum filtration device according to claim 1 or 2, wherein the tray cleaning liquid is supplied into the vacuum tray, and the washing is performed while overflowing from the vacuum tray to another vacuum tray adjacent to the vacuum tray. . The cleaning method of a vacuum filtration device according to claim 1 or 2, wherein the temperature of said tray cleaning liquid is maintained at a temperature equal to or higher than a temperature at which recrystallization of a crystal component is performed. A plurality of vacuum trays connected to the vacuum suction device through a vacuum line under the filter cloth provided to be able to run horizontally on the main body of the apparatus are provided in the traveling direction of the filter cloth, and the slurry supplied on the filter cloth is transferred to the filter cloth by the vacuum tray. In the vacuum filtration apparatus which consists of a structure which filters by vacuum suction through, Vacuum pressure measuring means for measuring the vacuum pressure in the vacuum line in at least one of the vacuum trays of the plurality of vacuum trays is provided, cleaning liquid supply means for supplying the tray cleaning liquid to the vacuum tray is provided, The tray cleaning liquid is supplied to the vacuum tray by the cleaning liquid supply means based on the vacuum pressure measured by the vacuum pressure measuring means, the tray cleaning liquid is immersed in the vacuum tray, and the vacuum tray is cleaned. Vacuum filtration device. The vacuum tray according to claim 6, wherein the plurality of vacuum trays are used for cake formation, cake cleaning, and dehydration, wherein the vacuum pressure measuring means and the cleaning liquid supplying means are at least in the vacuum line of the vacuum tray for dewatering. Vacuum filtration device, characterized in that installed.

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