JP2008546511A - Slurry dehydration drying method and dehydration drying apparatus - Google Patents

Abstract

The dehydrating and drying apparatus includes a filter press (1) having a filter chamber (130) and a filter plate (100, 110). The first filter plate (100) includes a diaphragm (102), a filter cloth (103) sandwiched between the diaphragm (102) and the filter chamber (130), and a heat medium chamber (S2). The second filter plate (110) includes a metal heat transfer member (112), a filter cloth (113) sandwiched between the heat transfer surface of the heat transfer member (112) and the filter chamber (130), and heat And a medium chamber (S12). The dehydrating and drying apparatus includes a heating mechanism (20, 26) for heating the slurry to a set temperature higher than a predetermined saturated steam temperature, and a pressure reducing mechanism for instantaneously guiding the heated slurry to a pressure corresponding to the predetermined saturated steam temperature. And.

Description

  TECHNICAL FIELD The present invention relates to a slurry dehydration drying method and a dehydration drying apparatus, and more particularly, a dehydration drying method for dewatering and drying slurry such as sludge discharged from water and sewage systems, rural village drainage treatment facilities, human waste treatment facilities, industrial drainage facilities, and the like. And a dehydration drying apparatus.

  Conventionally, in order to dehydrate and dry sludge such as sludge, it is necessary to install a dewatering device and a drying device separately, which has a high initial cost and requires a lot of labor for maintenance. Met. In order to solve such a problem, a dehydrating and drying apparatus provided with a filter press (pressure dehydrator) is known. Such a dehydration drying apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-232109. In this type of dehydration drying apparatus, the slurry in the filter chamber of the filter press is squeezed while being heated with a heat medium such as hot water, and at the same time, the slurry is dehydrated and dried by evacuating the filter press with a vacuum pump. The dehydrated and dried slurry is discharged from the filter press as a cake.

  However, the conventional dehydrating and drying apparatus has a problem that the apparatus becomes large because the evaporation rate is insufficient particularly for organic sludge. Further, when the peelability of the cake from the filter cloth deteriorates, there is a problem that a great deal of labor is required for maintenance of the dehydrating and drying apparatus. Furthermore, there is a problem that it takes time until the inside of the filter press has a predetermined degree of vacuum after the vacuum pump is operated.

  The present invention has been made in view of such problems of the prior art, and it is possible to perform dewatering and drying of the slurry more efficiently and in a short time, and to improve the peelability of the cake. An object of the present invention is to provide a dehydration drying method and a dehydration drying apparatus.

  According to the first aspect of the present invention, there is provided a slurry dehydrating and drying method capable of performing slurry dehydration and drying more efficiently and in a short time and improving the peelability of the cake. According to this method, the first filter plate and the second filter plate are arranged, and a filter chamber is formed between the first filter plate and the second filter plate. The first filter plate has a filter cloth, a diaphragm, and a heat medium chamber. The second filter plate has a filter cloth, a metal heat transfer member, and a heat medium chamber. Slurry is fed to the filter chamber. As for the slurry, the slurry in the filter chamber is filtered by the filter cloths of the first filter plate and the second filter plate. A heat medium is supplied to the heat medium chamber formed in the first filter plate, and the diaphragm of the first filter plate is pressed against the slurry in the filter chamber and squeezed. A heat medium is supplied to the heat medium chamber formed in the second filter plate, and the heat of the heat medium is transmitted to the slurry through the heat transfer member of the second filter plate. After heating the slurry to a set temperature higher than a predetermined saturated steam temperature, the slurry is guided to a pressure corresponding to the predetermined saturated steam temperature, and a temperature difference between the set temperature and the predetermined saturated steam temperature is determined. The water in the slurry is self-evaporated. In this case, you may heat the said slurry from the time of the said filtration or the said pressing. Further, the self-evaporation of the water in the slurry may be repeated a plurality of times.

According to the second aspect of the present invention, there is provided a slurry dehydrating and drying method capable of performing slurry dehydration and drying more efficiently and in a short time and improving the peelability of the cake. According to this method, filter plates are arranged and a filter chamber is formed between the filter plates. Each filter plate has a filter cloth, a metal heat transfer member, and a heat medium chamber. Slurry is fed to the filter chamber. The slurry is filtered through the filter cloth of the filter plate. A heat medium is supplied to the heat medium chamber formed in the filter plate, and the heat of the heat medium is transmitted to the slurry through the heat transfer member of the filter plate. After heating the slurry to a set temperature higher than a predetermined saturated steam temperature, the slurry is guided to a pressure corresponding to the predetermined saturated steam temperature, and a temperature difference between the set temperature and the predetermined saturated steam temperature is determined. The water in the slurry is self-evaporated. In this case, the slurry may be heated during the filtration, during the filtration, or after completion of the filtration. Further, the self-evaporation of the water in the slurry may be repeated a plurality of times.
In addition, “dehydration” in the present specification is a concept including both dehydration by filtration and both dehydration by filtration and pressing.

  Further, during the filtration, during the squeezing, after the filtration, after the squeezing, during the self-evaporation of the water of the slurry, and after the self-evaporation of the water of the slurry, pressurized gas is supplied to the filter chamber You may let it pass.

  Here, the self-evaporation of water in the slurry may be repeated a plurality of times, and the pressurized gas may be ventilated after completion of the self-evaporation of the water in the slurry at least one time. As the pressurized gas, at least one of steam, air, dehumidified air, and warm exhaust gas can be used.

  The pressurized gas is supplied to the filter chamber via a blow line for blowing pressurized gas into the filter chamber, and the pressurized gas is supplied to the filter chamber via a filtrate discharge line for discharging filtrate from the filter chamber. May be discharged from. Alternatively, the pressurized gas is supplied to the filter chamber via at least one of a plurality of filtrate discharge lines that discharge the filtrate from the filter chamber, and the pressure gas is supplied via the other at least one of the plurality of filtrate discharge lines. Pressurized gas may be discharged from the filter chamber.

  Further, the filtration chamber may be sequentially connected to a plurality of vacuum tanks maintained at a pressure corresponding to the predetermined saturated vapor temperature or less, and the self-evaporation of the water in the slurry may be repeated a plurality of times. Thus, the slurry can be dried more efficiently and in a short time, and the inside of the filter press can be instantly evacuated.

  Further, a physical property value corresponding to the temperature of the slurry in the filter chamber may be measured, and the start and stop of the self-evaporation of water in the slurry may be controlled based on the physical property value. It is preferable to repeat the self-evaporation of the slurry water a plurality of times.

  The physical property value may be a temperature difference between the slurry temperature in the filter chamber, the inlet temperature of the heat medium chamber, and the outlet temperature of the heat medium chamber. In this case, when the measured temperature of the slurry in the filter chamber reaches a predetermined value or more, self-evaporation of the water in the slurry is started, and the measured inlet temperature of the heat medium chamber and the measured temperature When the temperature difference from the outlet temperature of the heat medium chamber reaches a predetermined value, the self-evaporation of the water in the slurry can be stopped.

  Alternatively, the physical property value may be a temperature difference between the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber. The slurry self-evaporation may be started and stopped when the temperature difference between the measured inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber reaches a predetermined value.

  The physical property value may be a temperature difference between the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber. In this case, when the temperature difference between the measured inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber reaches a predetermined value, self-evaporation of water in the slurry is started, and after a predetermined time has elapsed. You may stop the self-evaporation of the water | moisture content of the said slurry.

  The physical property value may be a temperature difference between the temperature of the filtrate discharged from the filter chamber, and the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber. In this case, when the temperature of the filtrate discharged from the filtration chamber measured above becomes a predetermined value or more, self-evaporation of the water of the slurry is started, and after a certain time has elapsed, or measured When the temperature difference between the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber reaches a predetermined value, the self-evaporation of water in the slurry can be stopped.

The physical property value is the temperature of the slurry in the filter chamber, and when the measured temperature of the slurry in the filter chamber reaches a predetermined value or more, self-evaporation of water in the slurry is started for a certain period of time. You may stop the self-evaporation of the water | moisture content of the said slurry after progress.
It is preferable that the self-evaporation of the slurry water is repeated a plurality of times at a predetermined frequency.

  The temperature difference between the set temperature and the predetermined saturated steam temperature is preferably in the range of 20 ° C to 70 ° C. Furthermore, it is preferable that the pressure corresponding to the predetermined saturated steam temperature is 0.03 MPa or less.

  According to the third aspect of the present invention, there is provided a slurry dehydration drying method capable of performing slurry dehydration and drying more efficiently and in a short time and improving the peelability of the cake. The apparatus includes a filter press having a first filter plate, a second filter plate, and at least one filter chamber formed between the first filter plate and the second filter plate. The first filter plate includes a diaphragm, a filter cloth disposed between the diaphragm and the filter chamber, and a heat medium chamber that presses the diaphragm into the filter chamber by the supplied heat medium. The second filter plate transfers the heat of the metal heat transfer member having the heat transfer surface, the filter cloth disposed between the heat transfer surface of the heat transfer member and the filter chamber, and the supplied heat medium. It has a heat medium chamber that communicates with the slurry via the hot surface. This apparatus includes a heating mechanism for heating the slurry to a set temperature higher than a predetermined saturated steam temperature. This apparatus also includes a pressure reducing mechanism that instantaneously guides the slurry heated by the heating mechanism to a pressure corresponding to a predetermined saturated steam temperature.

  The 2nd filter plate is equipped with the resin-made frame body arrange | positioned at the peripheral part of the heat-transfer surface of a heat-transfer member. Alternatively, the heat transfer member of the second filter plate may be formed integrally with the frame body.

  According to the fourth aspect of the present invention, there is provided a slurry dehydrating and drying apparatus capable of performing slurry dehydration and drying more efficiently and in a short time and improving the peelability of the cake. The apparatus comprises a filter press having a filter plate and at least one filter chamber formed between the filter plates. Each filter plate includes a metal heat transfer member having a heat transfer surface, a filter cloth disposed between the heat transfer surface of the heat transfer member and the filter chamber, and a heat transfer surface for transferring the heat of the supplied heat medium. There is a heat medium chamber that communicates to the slurry via This apparatus includes a heating mechanism for heating the slurry to a set temperature higher than a predetermined saturated steam temperature. This apparatus also includes a pressure reducing mechanism that instantaneously guides the slurry heated by the heating mechanism to a pressure corresponding to the predetermined saturated steam temperature.

  The filter plate may include a resin frame at the peripheral edge of the heat transfer member. Alternatively, the heat transfer member of the filter plate may be formed integrally with the frame body.

  In addition, this apparatus may be provided with a ventilation mechanism that allows pressurized gas to pass through the filter chamber. Further, as the pressurized gas, at least one of steam, air, dehumidified air, and warm exhaust gas can be used. Further, the pressurized gas is supplied to the filter chamber via a blow line for blowing pressurized gas into the filter chamber, and the pressurized gas is supplied via a filtrate discharge line for discharging filtrate from the filter chamber. The aeration mechanism may be configured to discharge from the filter chamber. Alternatively, the pressurized gas is supplied to the filter chamber via at least one of a plurality of filtrate discharge lines that discharge the filtrate from the filter chamber, and the pressure gas is supplied via the other at least one of the plurality of filtrate discharge lines. The aeration mechanism may be configured to discharge the pressurized gas from the filter chamber. The aeration mechanism may include a plurality of vacuum tanks connected in parallel to the filter chamber of the filter press. Each of the plurality of vacuum tanks may be held below a pressure corresponding to the predetermined saturated steam temperature. The ventilation mechanism may include a plurality of valves that switch connection between the plurality of vacuum tanks and the filter chamber of the filter press. The plurality of vacuum tanks preferably have a cooling mechanism.

  The apparatus may further include a detector that measures a physical property value corresponding to the temperature of the slurry in the filter chamber. The decompression mechanism is controlled based on the physical property value measured by the detector.

  The at least one detector may include a detector that measures the temperature of the slurry in the filter chamber. The at least one detector may include a first detector that measures an inlet temperature of the heat medium chamber and a second detector that measures an outlet temperature of the heat medium chamber. Alternatively, the at least one detector may include a detector that measures the temperature of the filtrate discharged from the filter chamber.

  The temperature difference between the set temperature and the predetermined saturated steam temperature is preferably in the range of 20 ° C to 70 ° C. Furthermore, it is preferable that the pressure corresponding to the predetermined saturated steam temperature is 0.03 MPa or less.

  According to the present invention, after the slurry is heated and guided under a reduced pressure, the cake can be cracked by causing bumping due to acceleration of self-evaporation regardless of the type of slurry. As a result, the evaporation area increases, and the slurry can be dehydrated and dried more efficiently and in a short time.

  Further, the cake having adhesiveness can be easily separated from the filter cloth by cracking the cake. Therefore, the labor required for maintenance of the dehydration drying apparatus can be greatly reduced.

  Furthermore, if a filter plate having a diaphragm is not used, the heat transfer surface can be constituted by a metal heat transfer member on both sides, so that the heat transfer performance can be remarkably improved.

  Furthermore, since the filter chambers are sequentially connected to a plurality of vacuum tanks maintained at a pressure corresponding to a predetermined saturated steam temperature or less, the inside of the filter press can be quickly guided to a desired pressure, and a cooling device or a vacuum pump The capacity of the dehydrating and drying apparatus can be efficiently operated.

  The above object and other objects and advantages of the present invention will become apparent from the following description in light of the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.

  Hereinafter, embodiments of a dehydration drying apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 13. 1 to 13, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic diagram showing a dehydration drying apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the dehydrating and drying apparatus includes a filter press 1 for dehydrating and drying slurry such as sludge. The dehydrating and drying apparatus also has a slurry supply line 10 for supplying slurry to a filter chamber formed inside the filter press 1, and a heat medium circulation line 20 for circulating a heat medium (for example, hot water) through the filter press 1. A vacuum line 30 for evacuating the filter chamber in the filter press 1, a blow line 40 for blowing compressed air into the filter chamber in the filter press 1, and discharging residual slurry in the filter press 1. The slurry discharge line 50 is provided. A slurry supply line 10, a heat medium circulation line 20, a vacuum line 30, a blow line 40, and a slurry discharge line 50 are connected to the filter press 1. Further, the filter press 1 is provided with a filter chamber temperature detector 2 for detecting the temperature in the filter chamber, and an open valve 3 for discharging the gas accumulated in the heat medium circulation line 20 in the filter press 1.

  A slurry supply pump 11 is connected to the end of the slurry supply line 10. The slurry supply pump 11 supplies the slurry to the filter chamber in the filter press 1 through the slurry supply line 10. The slurry supply line 10 is provided with a slurry supply valve 12 that controls the supply of the slurry to the filter press 1 and a slurry pressure detector 14 that detects the pressure of the slurry in the slurry supply line 10. .

  The heat medium circulation line 20 includes a heat medium circulation line 20 </ b> A located on the upstream side of the filter press 1 and a heat medium circulation line 20 </ b> B located on the downstream side of the filter press 1. The heat medium circulation line 20 </ b> A includes a heat medium circulation pump 21 that circulates the heat medium in the heat medium circulation line 20, and a first heat medium temperature detector 22 that detects the temperature of the heat medium at the inlet of the filter press 1. Is provided. The heat medium circulation line 20B includes a second heat medium temperature detector 23 that detects the temperature of the heat medium at the outlet of the filter press 1, and a heat medium pressure detector that detects the pressure of the heat medium at the outlet of the filter press 1. 24 and a back pressure valve 25 capable of adjusting the pressure of the heat medium flowing through the heat medium circulation line 20B. By operating the back pressure valve 25, the pressure of the heat medium supplied to the filter press 1 can be adjusted.

  The heat medium circulation line 20A located on the upstream side of the filter press 1 and the heat medium circulation line 20B located on the downstream side of the filter press 1 are a heating tank 26 for heating the heat medium circulating in the heat medium circulation line 20. Are connected to each. With such a configuration, the heating medium is heated in the heating tank 26 and then supplied into the filter press 1 via the heating medium circulation line 20A, so that at least the slurry in the filter chamber of the filter press 1 is heated. It has become. The heat medium leaving the filter chamber is returned to the heating tank 26 via the heat medium circulation line 20B. Thus, the heating medium circulating lines 20A and 20B, the heating medium circulation pump 21, and the heating tank 26 constitute a heating mechanism that heats the slurry in the filter chamber of the filter press 1. In the present embodiment, the slurry in the filter chamber of the filter press 1 is heated while being squeezed by the heat medium circulating in the heat medium circulation line 20. It is configured as a dryer.

  A vacuum pump 31 is connected to the end of the vacuum line 30. The vacuum pump 31 evacuates the filter chamber in the filter press 1 through the vacuum line 30. In addition, the vacuum line 30 is provided with a first switching valve (open / close valve) 32A, a condenser (condenser) 33 for condensing the vapor guided from the filter press 1, and a vacuum tank 34. The vacuum line 30, the vacuum pump 31, the first switching valve 32 </ b> A, and the vacuum tank 34 constitute a pressure reducing mechanism that condenses the slurry in the filter chamber of the filter press 1.

  A cooling liquid is supplied to the condenser 33, and the steam guided from the filter press 1 to the condenser 33 is condensed by exchanging heat with the cooling liquid in the condenser 33 and discharged from the condenser 33 as a condensed liquid. It has become.

  As shown in FIG. 1, a filtrate discharge line 35 is connected to the vacuum line 30. The filtrate discharge line 35 discharges the filtrate discharged from the filter chamber in the filter press 1 as the slurry is dehydrated. The filtrate discharge line 35 is provided with a second switching valve (open / close valve) 32B. When the slurry in the filter chamber is squeezed by the heat medium, the volume of the filter chamber decreases. Thereby, the slurry in the filter chamber is dehydrated to form a cake. As the slurry is dehydrated, the filtrate is discharged from the filter chamber, and this filtrate is discharged to the outside of the dehydrating and drying apparatus via the filtrate discharge line 35.

  When the filter chamber of the filter press 1 is evacuated by the vacuum pump 31, the first switching valve 32A is opened and the second switching valve 32B is closed. When discharging the filtrate from the filter chamber, the first switching valve 32A is closed and the second switching valve 32B is opened. Further, by opening the second switching valve 32B, the pressure in the filter chamber in the filter press 1 can be instantaneously guided from vacuum to atmospheric pressure.

  A compressor (not shown) is connected to the blow line 40. Thus, compressed air is blown from the compressor into the filter chamber via the blow line 40, and the slurry remaining in the filter press 1 and the slurry supply port of the filter chamber is discharged through the slurry discharge line 50 by this compressed air. It is like that. The blow line 40 is provided with an air valve 41, and the slurry discharge line 50 is provided with a slurry discharge valve 51.

  FIG. 2 is a cross-sectional view schematically showing the filter press 1 shown in FIG. As shown in FIG. 2, the filter press 1 includes a first filter plate 100 and a second filter plate 110, and a pair of fixing plates 120A and 120B for fastening the filter plates 100 and 110 from both sides. . The first filter plate 100 and the second filter plate 110 are alternately arranged, and filter chambers 130 are formed between the filter plates, respectively. It arrange | positions so that the both sides of the filter chamber 130 may be opposed on both sides of the chamber 130.

  A slurry supply pipe 121 is attached to the central portion of one fixed plate 120A, and this slurry supply pipe 121 is connected to the slurry supply line 10 (see FIG. 1). A slurry discharge pipe 122 is attached to the central portion of the other fixed plate 120B, and this slurry discharge pipe 122 is connected to the slurry discharge line 50 (see FIG. 1). Further, the filter chamber temperature detector 2 described above is disposed in the vicinity of the fixed plate 120A, and the temperature of the slurry in the filter chamber 130 is detected by the filter chamber temperature detector 2. A thermocouple is preferably used as the filter chamber temperature detector 2.

  As shown in FIG. 2, the first filter plate 100 includes a resin frame body 101, a diaphragm 102, and a filter cloth 103 disposed between the diaphragm 102 and the filter chamber 130. The second filter plate 110 includes a resin frame body 111, a metal heat transfer member 112, and a filter cloth 113 disposed between the heat transfer member 112 and the filter chamber 130. . Thus, in this embodiment, the filter press 1 uses two types of filter plates, the first filter plate 100 having the diaphragm 102 and the second filter plate 110 having the metal heat transfer member 112. The filter press 1 is a single-sided squeezing type.

  FIG. 3 is a side view showing the first filter plate 100 with the filter cloth 103 removed. 4A is a cross-sectional view taken along line AA in FIG. 3, and FIG. 4B is a cross-sectional view taken along line BB in FIG. As shown in FIGS. 3 and 4B, an opening 104 is formed at the center of the first filter plate 100 corresponding to the slurry supply pipe 121 described above. The opening 104 passes through the frame body 101, the diaphragm 102, and the filter cloth 103, and adjacent filter chambers 130 communicate with each other through the opening 104.

  4A and 4B, a plurality of protrusions 105 are formed on the surface of the diaphragm 102 on the filter cloth 103 side. These protrusions 105 form a minute filtrate chamber S 1 between the diaphragm 102 and the filter cloth 103. As shown in FIG. 4A, a filtrate discharge passage 106 communicating with the filtrate chamber S1 is formed in the frame 101, and the filtrate chamber S1 between the diaphragm 102 and the filter cloth 103 is connected to the filtrate discharge passage 106. To the vacuum line 30 (see FIG. 1). Thereby, a vacuum is formed in the filtrate chamber S <b> 1 via the vacuum pump 31. Thereby, the water | moisture content of a slurry passes through the filter cloth 103, enters into filtrate chamber S1, passes through the filtrate discharge channel 106, and is discharged | emitted from the filtrate discharge line 35 (refer FIG. 1).

  A recess 107 is formed on the surface of the frame body 101, and the heat medium chamber S <b> 2 is formed between the diaphragm 102 and the frame body 101 covering almost the entire surface of the frame body 101 by the recess 107. . In addition, as shown in FIG. 4A, the frame 101 is formed with a heat medium supply passage 108 and a heat medium discharge passage 109 that communicate with the heat medium chamber S2. The heat medium chamber S2 between the diaphragm 102 and the frame body 101 communicates with the heat medium circulation line 20A (see FIG. 1) via the heat medium supply passage 108. Accordingly, the heat medium is supplied from the heat medium circulation line 20A to the heat medium chamber S2 via the heat medium supply passage 108. The heat medium chamber S2 communicates with the heat medium circulation line 20B (see FIG. 1) via the heat medium discharge passage 109. Accordingly, the heat medium supplied to the heat medium chamber S2 is sent to the heat medium circulation line 20B via the heat medium discharge passage 109.

  5A and 5B are cross-sectional views of the second filter plate 110. FIG. 5A is a cross-sectional view in the same plane as FIG. 4A, and FIG. 5B is a cross-sectional view in the same plane as FIG. 4B. As shown in FIG. 5B, similarly to the first filter plate 100, an opening 114 is formed at the center of the second filter plate 110 corresponding to the above-described slurry supply pipe 121. The opening 114 passes through the frame body 111, the heat transfer member 112, and the filter cloth 113, and adjacent filter chambers 130 communicate with each other through the opening 114.

  5A and 5B, a plurality of protrusions 115 are formed on the surface of the heat transfer member 112 on the filter cloth 113 side. These protrusions 115 form a minute filtrate chamber S11 between the heat transfer member 112 and the filter cloth 113. As shown in FIG. 5A, a filtrate discharge passage 116 communicating with the filtrate chamber S11 is formed in the frame body 111, and the filtrate chamber S11 between the heat transfer member 112 and the filter cloth 113 has a filtrate discharge passage. 116 communicates with the vacuum line 30 (see FIG. 1). Thereby, a vacuum is formed in the filtrate chamber S11 via the vacuum pump 31. Thereby, the water | moisture content of slurry passes through the filter cloth 113, enters into filtrate chamber S11, and is discharged | emitted from the filtrate discharge line 35 (refer FIG. 1) through the filtrate discharge channel | path 116. FIG. A support member (not shown) may be provided between the heat transfer member 112 and the heat transfer member 112 so as to bypass the heat medium.

  The metal heat transfer member 112 has a hollow portion (heat medium chamber) S12 therein, and a resin frame body 111 is disposed at the peripheral edge of the heat medium chamber S12. As shown in FIG. 5A, the frame body 111 is formed with a heat medium supply passage 118 and a heat medium discharge passage 119 communicating with the heat medium chamber S12. The heat medium chamber S12 inside the heat transfer member 112 communicates with the heat medium circulation line 20A (see FIG. 1) via the heat medium supply passage 118. Accordingly, the heat medium is supplied from the heat medium circulation line 20A to the heat medium chamber S12 through the heat medium supply passage 118. The heat medium chamber S12 communicates with the heat medium circulation line 20B (see FIG. 1) via the heat medium discharge passage 119. Accordingly, the heat medium supplied to the heat medium chamber S12 is sent to the heat medium circulation line 20B via the heat medium discharge passage 119.

  The first filter plate 100 and the second filter plate 110 described above are alternately arranged in parallel, and between the filter cloth 103 of the first filter plate 100 and the filter cloth 113 of the second filter plate 110. A plurality of filter chambers 130 are formed. These filter plates 100 and 110 are configured to be relatively movable so as to approach and separate from each other, and are fixed by fastening the fixing plate 120A and the fixing plate 120B to each other by a fastening device (not shown). Is done.

  A first example of a slurry dehydrating and drying process using the dehydrating and drying apparatus having such a configuration will be described. The slurry dehydrating and drying process in this example includes a dehydrating process for dewatering the slurry by filtering and squeezing the slurry, a drying process for drying the slurry after dehydration, and a blowing process for blowing the slurry after dehydration or drying. is doing.

[Dehydration process]
(1) Filtration First, the slurry is supplied to the filter press 1 by the slurry supply pump 11 via the slurry supply line 10, the slurry supply valve 12, and the slurry pressure detector 14, and filled in the filter chamber 130. When the slurry is further supplied to the filter chamber 130, the water in the slurry becomes a filtrate and is discharged from the filtrate chambers S 1 and S 11 through the filtrate discharge passages 106 and 116 through the filtrate discharge line 35.

  The slurry supply pressure may be set to a low pressure of, for example, an absolute pressure of 0.15 MPa to 0.20 MPa at the start of filtration, gradually increased as the filtration proceeds, and finally set to an absolute pressure of 0.6 MPa or more. preferable. In addition, it is preferable to select an optimum value for the filtration time depending on the properties of the slurry.

  The slurry may be preheated before being supplied to the filter press 1 (preliminary warming filtration). In this case, by supplying the heated slurry to the filter press 1, the filterability of the slurry can be improved. In parallel with the filtration, the heat medium heated in the heating tank 26 is circulated and supplied to the heat medium chambers S2 and S12 in the filter press 1 through the heat medium circulation lines 20A and 20B by the heat medium circulation pump 21. The slurry may be warmed (warm filtration). In this case, the filterability of the slurry can be improved by filtering while heating the slurry.

(2) Squeeze Next, the heat medium heated by the heat medium circulation pump 21 is supplied to the heat medium chambers S2 and S12 in the filter press 1 through the heat medium circulation line 20A. The slurry in the chamber 130 is heated by the heat medium. The heat medium returns to the heating tank 26 via the heat medium circulation line 20B, the second heat medium temperature detector 23, and the heat medium pressure detector 24, and is heated by the heating tank 26. It is supplied again to the heat medium chambers S2 and S12 in the filter press 1 through the circulation line 20A.

  The pressure (squeezing pressure) of the heat medium in the heat medium chamber S2 is adjusted to a predetermined value by the back pressure valve 25 provided in the heat medium circulation line 20B. When the heat medium is supplied to the heat medium chamber S2, the diaphragm 102 of the first filter plate 100 expands toward the filter chamber 130, whereby the slurry in the filter chamber 130 is squeezed and heated at the same time. The water in the slurry becomes pressed filtrate and is discharged from the filtrate chambers S1 and S11 through the filtrate discharge passages 106 and 116 through the filtrate discharge line 35, respectively.

  Thus, by filtering and pressing the slurry, the slurry is dehydrated and gradually becomes a cake. In this dehydration step, dehydration may be performed only by filtration without squeezing.

  In addition, the opening valve 3 (refer FIG. 1) may be opened temporarily at the time of pressing start, and the gas accumulated in heat-medium chamber S2, S12 may be discharged | emitted. Moreover, it is preferable that the pressing pressure with respect to a slurry can be adjusted within the range of absolute pressure 0.1MPa (atmospheric pressure) to 1.6MPa. The squeezing pressure is gradually increased after the start of squeezing and is preferably set to a slurry supply pressure or higher and 1.6 MPa or lower. The temperature of the heat medium is not particularly limited as long as it is equal to or higher than the saturated vapor temperature corresponding to the vacuum pressure, but is preferably 70 ° C or higher. In this way, the slurry is heated to a set temperature higher than a predetermined saturated steam temperature (saturated steam temperature corresponding to the vacuum pressure).

[Drying process]
In the drying step, the heat medium is circulated in the filter press 1 in the same manner as in the squeezing in the dehydration step, but the pressure of the heat medium adjusted by the back pressure valve 25 is preferably set lower than the squeezing pressure at the time of squeezing. . Simultaneously with the start of the drying process, the first switching valve 32A is opened, and the filtrate chambers S1, S11 in the filter press 1 are evacuated by the vacuum pump 31 through the condenser 33, the vacuum tank 34, and the vacuum line 30, and the slurry is discharged. To vacuum pressure. It is also possible to operate the vacuum pump 31 in advance during the squeezing process to reduce the pressure in the vacuum tank 34 and open the first switching valve 32A simultaneously with the start of the drying process to instantly evacuate the filtrate chambers S1, S11.

  During the above-described pressing, the slurry in the filter chamber 130 is sufficiently heated by the heat medium. Since the temperature difference between the set temperature of the slurry and the saturated steam temperature corresponding to the vacuum pressure is large, the slurry in the filter press 1 is instantaneously guided under the vacuum pressure in the drying process, so that the heat supplied by the heat medium is reduced. In addition, the thermal energy held by the slurry is used for evaporation. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate (evaporation rate).

  The efficiency of the vacuum pump 31 can be increased by supplying the coolant to the condenser 33 and returning the steam generated from the slurry (cake) in the filter chamber 130 to water. The vacuum pressure in the drying process is preferably an absolute pressure of 0.03 MPa or less. When the set temperature is 100 ° C. or higher, which is a saturated steam temperature corresponding to atmospheric pressure, the first switching valve 32A is kept closed after the drying process is started, and the second switching valve 32B is opened to make a slurry. It is also possible to exhaust the vapor generated from the filtrate from the filtrate discharge line 35 instead of from the vacuum line 30. Also in this case, the slurry in the filter chamber 130 is sufficiently heated during the squeezing, and the difference between the set temperature of the slurry and the saturated steam temperature corresponding to the atmospheric pressure is large, so that the thermal energy possessed by the slurry is evaporated. Used. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate.

  The drying speed increases as the difference between the temperature of the slurry (cake) in the filter chamber 130 and the saturated water vapor temperature corresponding to a predetermined vacuum pressure increases. However, as the drying process starts, the temperature of the cake rapidly decreases due to water evaporation, the temperature difference becomes smaller, and the drying rate decreases. Therefore, the heating speed at the initial stage of the drying process can be maintained (repeated drying) by repeating the operation of immediately heating the cake to a predetermined temperature and then immediately leading to the vacuum (under reduced pressure) a plurality of times.

  Even when the drying process is repeated in this manner, the heat medium is circulated at a pressure lower than the pressing pressure, the first switching valve 32A is opened, and the vacuum pump 31 is passed through the condenser 33, the vacuum tank 34, and the vacuum line 30. The filtrate chambers S1 and S11 in the filter press 1 are evacuated. Then, after the temperature of the cake in the filter chamber 130 is lowered by a predetermined value from the heat medium temperature, the first switching valve 32A is closed. Thereafter, after the temperature of the cake in the filter chamber 130 rises to a predetermined temperature, the first switching valve 32A is opened again, and the filtrate chambers S1 and S11 are evacuated by the vacuum pump 31. Such an operation is repeated a predetermined number of times.

[Blow process]
A blow process can be performed at arbitrary timings, such as after completion | finish of pressing of a spin-drying | dehydration process, or completion | finish of a drying process. In the blow process, the air valve 41 and the slurry discharge valve 51 are opened, compressed air is supplied to the filter press 1 via the blow line 40, and the slurry is discharged via the slurry discharge line 50.

The end point of filtration and pressing in the dehydration step, the end point of the drying step, or the switching timing to the subsequent step can be performed based on a preset time, but can also be detected by the following method.
(1) End point of filtration in the dehydration step: Detecting a time point when the amount of solids injected into the filter chamber 130 reaches a predetermined value.
(2) End point of squeezing in the dehydration step: When the pressure in the filter chamber 130 falls below the squeezing pressure by the heat medium, when the flow rate of the squeezed filtrate or the squeezed filtrate amount reaches a predetermined value, The time when the temperature of the cake reaches a predetermined value is detected.
(3) End point of drying process: detecting temperature change of cake in filter chamber 130, temperature change of heating medium, or temperature change of filtrate discharge passages 106, 116.

  Next, a second example of the slurry dehydration drying process using the above-described dehydration drying apparatus will be described. The slurry dehydrating and drying process in this example includes a dehydrating process for dewatering the slurry by filtering and squeezing the slurry, a drying process for drying the slurry after dehydration, and a blowing process for blowing the slurry after dehydration or drying. is doing.

[Dehydration process]
(1) Filtration First, the slurry is supplied to the filter press 1 by the slurry supply pump 11 via the slurry supply line 10, the slurry supply valve 12, and the slurry pressure detector 14, and filled in the filter chamber 130. When the slurry is further supplied to the filter chamber 130, the water in the slurry becomes a filtrate and is discharged from the filtrate chambers S 1 and S 11 through the filtrate discharge passages 106 and 116 through the filtrate discharge line 35.

  The slurry supply pressure may be set to a low pressure of, for example, an absolute pressure of 0.15 MPa to 0.20 MPa at the start of filtration, gradually increased as the filtration proceeds, and finally set to an absolute pressure of 0.6 MPa or more. preferable. In addition, it is preferable to select an optimum value for the filtration time depending on the properties of the slurry.

  The slurry may be preheated before being supplied to the filter press 1 (preliminary warming filtration). In this case, by supplying the heated slurry to the filter press 1, the filterability of the slurry can be improved. In parallel with the filtration, the heat medium heated in the heating tank 26 is circulated and supplied to the heat medium chambers S2 and S12 in the filter press 1 through the heat medium circulation lines 20A and 20B by the heat medium circulation pump 21. The slurry may be warmed (warm filtration). In this case, the filterability of the slurry can be improved by filtering while heating the slurry.

(2) Squeeze Next, the heat medium heated by the heat medium circulation pump 21 is supplied to the heat medium chambers S2 and S12 in the filter press 1 through the heat medium circulation line 20A. The slurry in the chamber 130 is heated by the heat medium. The heat medium returns to the heating tank 26 via the heat medium circulation line 20B, the second heat medium temperature detector 23, and the heat medium pressure detector 24, and is heated by the heating tank 26. It is supplied again to the heat medium chambers S2 and S12 in the filter press 1 through the circulation line 20A.

  The pressure (squeezing pressure) of the heat medium in the heat medium chamber S2 is adjusted to a predetermined value by the back pressure valve 25 provided in the heat medium circulation line 20B. When the heat medium is supplied to the heat medium chamber S2, the diaphragm 102 of the first filter plate 100 expands toward the filter chamber 130, whereby the slurry in the filter chamber 130 is squeezed and heated at the same time. The water in the slurry becomes pressed filtrate and is discharged from the filtrate chambers S1 and S11 through the filtrate discharge passages 106 and 116 through the filtrate discharge line 35, respectively.

  Thus, by filtering and pressing the slurry, the slurry is dehydrated and gradually becomes a cake. In this dehydration step, dehydration may be performed only by filtration without squeezing.

  In addition, the opening valve 3 (refer FIG. 1) may be opened temporarily at the time of pressing start, and the gas accumulated in heat-medium chamber S2, S12 may be discharged | emitted. Moreover, it is preferable that the pressing pressure with respect to a slurry can be adjusted within the range of absolute pressure 0.1MPa (atmospheric pressure) to 1.6MPa. The squeezing pressure is gradually increased after the start of squeezing and is preferably set to a slurry supply pressure or higher and 1.6 MPa or lower. The temperature of the heat medium is not particularly limited as long as it is equal to or higher than the saturated vapor temperature corresponding to the vacuum pressure, but is preferably 70 ° C or higher. In this way, the slurry is heated to a set temperature higher than a predetermined saturated steam temperature (saturated steam temperature corresponding to the vacuum pressure).

[Drying process]
In the drying step, the heat medium is circulated in the filter press 1 in the same manner as in the squeezing in the dehydration step, but the pressure of the heat medium adjusted by the back pressure valve 25 is preferably set lower than the squeezing pressure at the time of squeezing. . Simultaneously with the start of the drying process, the first switching valve 32A is opened, and the filtrate chambers S1, S11 in the filter press 1 are evacuated by the vacuum pump 31 through the condenser 33, the vacuum tank 34, and the vacuum line 30, and the slurry is discharged. To vacuum pressure. It is also possible to operate the vacuum pump 31 in advance during the squeezing process to reduce the pressure in the vacuum tank 34 and open the first switching valve 32A simultaneously with the start of the drying process to instantly evacuate the filtrate chambers S1, S11.

  During the above-described pressing, the slurry in the filter chamber 130 is sufficiently heated by the heat medium. Since the temperature difference between the set temperature of the slurry and the saturated steam temperature corresponding to the vacuum pressure is large, the slurry in the filter press 1 is instantaneously guided under the vacuum pressure in the drying process, so that the heat supplied by the heat medium is reduced. In addition, the thermal energy held by the slurry is used for evaporation. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate (evaporation rate).

  The efficiency of the vacuum pump 31 can be increased by supplying the coolant to the condenser 33 and returning the steam generated from the slurry (cake) in the filter chamber 130 to water. The vacuum pressure in the drying process is preferably an absolute pressure of 0.03 MPa or less. When the set temperature is 100 ° C. or higher, which is a saturated steam temperature corresponding to atmospheric pressure, the first switching valve 32A is kept closed after the drying process is started, and the second switching valve 32B is opened to make a slurry. It is also possible to exhaust the vapor generated from the filtrate from the filtrate discharge line 35 instead of from the vacuum line 30. Also in this case, the slurry in the filter chamber 130 is sufficiently heated during the squeezing, and the difference between the set temperature of the slurry and the saturated steam temperature corresponding to the atmospheric pressure is large, so that the thermal energy possessed by the slurry is evaporated. Used. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate.

  The drying speed increases as the difference between the temperature of the slurry (cake) in the filter chamber 130 and the saturated water vapor temperature corresponding to a predetermined vacuum pressure increases. However, as the drying process starts, the temperature of the cake rapidly decreases due to water evaporation, the temperature difference becomes smaller, and the drying rate decreases. Thus, after the cake is heated to a predetermined temperature, the operation of immediately leading to the vacuum (under reduced pressure) is repeated a plurality of times, so that the initial slurry drying speed in the drying process can be maintained (repeated drying).

  Here, the greater the difference between the set temperature and the saturated steam temperature, the greater the amount of heat retained in the slurry, so that the slurry drying effect increases. Therefore, when drying repeatedly, the timing of the start and stop of slurry self-evaporation greatly affects the overall efficiency. This timing is determined by measuring the temperature of the slurry in the filter chamber. Since the temperature difference between the temperature of the heat medium at the inlet of the filter press 1 and the temperature of the heat medium at the outlet is considered to reflect the temperature of the slurry in the filter chamber, in this example, the first heat medium temperature detection is performed. Based on the temperature difference between the temperature of the heat medium at the inlet of the filter press 1 detected by the vessel 22 and the temperature of the heat medium at the outlet of the filter press 1 detected by the second heat medium temperature detector 23, The timing of the start and stop of self-evaporation is determined. The set temperature and the saturated steam temperature are preferably in the range of 20 ° C. to 70 ° C., and the pressure corresponding to the saturated steam temperature is preferably 0.03 MPa or less.

  For example, when the temperature of the slurry in the filter chamber 130 measured by the filter chamber temperature detector 2 becomes equal to or higher than a predetermined value, self-evaporation of the water in the slurry is started and measured by the heat medium temperature detectors 22 and 23. The self-evaporation of water in the slurry may be stopped when the temperature difference between the inlet temperature and the outlet temperature of the heat medium thus obtained reaches a predetermined value. Alternatively, when the temperature difference between the inlet temperature and the outlet temperature of the heat medium measured by the heat medium temperature detectors 22 and 23 reaches a predetermined value (for example, less than 2 ° C.), the self-evaporation of the water in the slurry is started. Even if the self-evaporation of the slurry moisture is stopped when the temperature difference becomes a predetermined value (for example, 2 ° C. or more) while the temperature difference is being self-evaporated and again reaches a predetermined value (for example, less than 2 ° C.). Good. In addition, when the temperature difference between the inlet temperature and the outlet temperature of the heat medium measured by the heat medium temperature detectors 22 and 23 reaches a predetermined value (for example, less than 2 ° C.), self-evaporation of the water in the slurry is started. The self-evaporation of the water in the slurry may be stopped after a certain time has elapsed (for example, several minutes, preferably 3 to 10 minutes). Moreover, when the temperature of the slurry in the filter chamber 130 measured by the filter chamber temperature detector 2 reaches a predetermined value, self-evaporation of the water in the slurry is started, and after a certain period of time (for example, several minutes, preferably The self-evaporation of the water in the slurry may be stopped in 3 to 10 minutes). Alternatively, the start and stop of self-evaporation may be repeated at regular intervals (for example, 3 minutes, preferably 3 to 10 minutes).

  In repeated drying, the cake in the filter chamber 130 is heated while circulating the heat medium at a pressure lower than the pressing pressure. When the difference between the measured value of the first heat medium temperature detector 22 and the measured value of the second heat medium temperature detector 23 reaches a predetermined value, the first switching valve 32A is opened, and the condenser 33 and the vacuum tank 34 are opened. The filtrate chambers S1 and S11 in the filter press 1 are evacuated by the vacuum pump 31 through the vacuum line 30. Then, after the temperature of the cake in the filter chamber 130 is lowered by a predetermined value from the heat medium temperature, the measurement value of the first heat medium temperature detector 22 and the measurement of the second heat medium temperature detector 23 are further performed. When the difference from the value reaches a predetermined value, the first switching valve 32A is closed. Thereafter, after the temperature of the cake in the filter chamber 130 rises to a predetermined temperature, the first switching valve 32A is opened again, and the filtrate chambers S1 and S11 are evacuated by the vacuum pump 31. Such an operation is repeated a predetermined number of times.

Here, the time T from the start of heating until the slurry reaches the set temperature may be obtained by calculation, and the slurry may be heated during this time T. Assuming that the amount of sludge to be injected F1, the total amount of filtrate F2, and the sludge concentration C, the amount S of solid matter in the filter chamber 130 is S = F1 · C, and the amount of water W in the filter chamber 130 is W = F1-F2-S. Can be approximated. When ρ _S is the specific heat of the solid and ρ _W is the specific heat of water, the amount of heat Q1 required to heat the fixed material from the predetermined saturated steam temperature T2 to the set temperature T1 is Q1 = (S · ρ _S + W · Ρ _W ) · (T1-T2). On the other hand, assuming that the heat medium inlet temperature T3 measured by the first heat medium temperature detector 22 and the heat medium outlet temperature T4 measured by the second heat medium temperature detector 23, the amount of heat transfer per hour. Since Q2 is Q2 = UA (T3-T4), the time T (minutes) required for heating is t = Q1 / Q2 · 60. After the slurry (sludge) is heated for the calculated time T, the first switching valve 32A is opened and the filtrate chambers S1 and S11 are evacuated by the vacuum pump 31.

[Blow process]
A blow process can be performed at arbitrary timings (after completion | finish of pressing of a dehydration process, after completion | finish of a drying process, etc.). In the blow process, the air valve 41 and the slurry discharge valve 51 are opened, compressed air is supplied to the filter press 1 via the blow line 40, and the slurry is discharged via the slurry discharge line 50.

The end point of filtration and pressing in the dehydration step, the end point of the drying step, or the switching timing to the subsequent step can be performed based on a preset time, but can also be detected by the following method.
(1) End point of filtration in the dehydration step: Detecting a time point when the amount of solids injected into the filter chamber 130 reaches a predetermined value.
(2) End point of squeezing in the dehydration step: When the pressure in the filter chamber 130 falls below the squeezing pressure by the heat medium, when the flow rate of the squeezed filtrate or the amount of squeezed filtrate reaches a predetermined value, or within the filter chamber 130 The time when the temperature of the cake reaches a predetermined value is detected.
(3) End point of drying process: detecting temperature change of cake in filter chamber 130, temperature change of heating medium, or temperature change of filtrate discharge passages 106, 116.

  In the above description, as the physical property value corresponding to the temperature of the slurry in the filter chamber, the temperature detected by the first heat medium temperature detector 22 and the temperature detected by the second heat medium temperature detector 23 are Although the example using a temperature difference and the example which opened and closed the 1st switching valve 32A for every fixed time were demonstrated, the physical-property value which can be used as a physical-property value according to the temperature of the slurry in a filter chamber is not restricted to this. . For example, a temperature detector can be inserted into the filtrate discharge passages 106 and 116 from the filtrate discharge line 35 in the vicinity of the filter press 1, and the temperature of the filtrate detected by the temperature detector can be used as the physical property value. In this case, when the detected temperature of the filtrate reaches a predetermined value or more, self-evaporation of the water in the slurry is started, and the inlet temperature of the heating medium measured by the heating medium temperature detectors 22 and 23 is calculated. The self-evaporation of the water in the slurry may be stopped when the temperature difference from the outlet temperature reaches a predetermined value or after a lapse of a certain time.

  FIG. 6 is a cross-sectional view showing a main part of the filter press 201 according to the second embodiment of the present invention. As shown in FIG. 6, the filter press 201 is formed by integrally forming a frame body 111 located at the peripheral edge of the second filter plate 110 in the first embodiment with a metal heat transfer member 312. It is different from the filter press 1 of the first embodiment. 7A and 7B are sectional views showing the second filter plate 310. FIG. As shown in FIGS. 7A and 7B, the heat transfer member 312 of the second filter plate 310 is formed in a hollow donut shape, and the hollow portion becomes the heat medium chamber S22. Since the other points of the filter press 201 are the same as those of the filter press 1 of the first embodiment, the description thereof is omitted.

  8A and 8B are sectional views showing a filter plate 410 according to the third embodiment of the present invention, and FIG. 8C is a partially enlarged view of FIG. 8B. Instead of the second filter plate 110 of the first embodiment, a filter plate 410 as shown in FIGS. 8A to 8C may be used. This filter plate 410 is different from the second filter plate 110 of the first embodiment in that an end portion of the heat transfer member 112 is bent into a bellows shape to form an expandable / contractible portion 412. As shown in FIG. 8C, the heat transfer member 112 is fixed to the frame body 111 by a fastener 112a. Since other points of the filter plate 410 are the same as those of the second filter plate 110 of the first embodiment described above, description thereof is omitted.

  FIG. 9 is a cross-sectional view showing a main part of a filter press 501 in the fourth embodiment of the present invention. The filter plate 100 having the above-described diaphragm 102 is inferior in heat transfer properties and the life of the diaphragm 102 is concerned. Therefore, in the filter press 501 in the present embodiment, a filter plate 110 (FIGS. 5A and 5B) having a metal heat transfer member 112 is disposed in place of the filter plate 100 in the first embodiment described above, respectively. A filter chamber 130 is formed between the filter plates 110. In the filter press 501 of the present embodiment, the slurry is not squeezed in the filter chamber 130, and it is not necessary to provide the back pressure valve 25 in the first embodiment described above.

  A slurry dehydration drying process using a dehydration drying apparatus having the filter press 501 will be described. The slurry dehydration drying process in the present embodiment includes a dehydration process for dehydrating the slurry by filtering the slurry, a drying process for drying the slurry after dehydration, and a blowing process for blowing the slurry after dehydration or drying. ing.

[Dehydration process (filtration)]
First, the slurry is supplied to the filter press 501 by the slurry supply pump 11 via the slurry supply line 10, the slurry supply valve 12, and the slurry pressure detector 14, and filled in the filter chamber 130. When the slurry is further supplied to the filter chamber 130, the water in the slurry becomes a filtrate, which is discharged from the filtrate chamber S 1 through the filtrate discharge passage 116 through the filtrate discharge line 35.

  The slurry supply pressure may be set to a low pressure of, for example, an absolute pressure of 0.15 MPa to 0.20 MPa at the start of filtration, gradually increased as the filtration proceeds, and finally set to an absolute pressure of 1.6 MPa or more. preferable. In addition, it is preferable to select an optimum value for the filtration time depending on the properties of the slurry.

  Note that the slurry may be preheated before being supplied to the filter press 501 (preliminary warming filtration). In this case, by supplying the heated slurry to the filter press 501, the filterability of the slurry can be improved. In parallel with the filtration, the heat medium heated in the heating tank 26 is circulated and supplied to the heat medium chamber S12 in the filter press 501 by the heat medium circulation pump 21 through the heat medium circulation lines 20A and 20B. May be warmed (warm filtration). In this case, the filterability of the slurry can be improved by filtering while heating the slurry.

[Drying process]
In the drying process, when the slurry is not heated at the time of filtration, the heat medium heated in the heating tank 26 is circulated and supplied to the heat medium chamber S12 in the filter press 501, and the temperature of the slurry is set to a predetermined vacuum pressure. Heat until the temperature is higher than the saturated water vapor temperature corresponding to. When heating is performed during filtration, the first switching valve 32A is opened simultaneously with the start of the drying process, and the filtrate chamber in the filter press 501 by the vacuum pump 31 via the condenser 33, the vacuum tank 34, and the vacuum line 30. S11 is evacuated and the slurry is brought to vacuum pressure. It is also possible to operate the vacuum pump 31 in advance during the filtration step to reduce the pressure in the vacuum tank 34 and open the first switching valve 32A simultaneously with the start of the drying step to instantly evacuate the filtrate chamber S11.

  The slurry in the filter chamber 130 is sufficiently heated by the heat medium. Since the temperature difference between the set temperature of the slurry and the saturated steam temperature corresponding to the vacuum pressure is large, the slurry in the filter press 501 is instantaneously brought under the vacuum pressure in the drying process, so that the heat supplied by the heat medium is reduced. In addition, the thermal energy held by the slurry is used for evaporation. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate (evaporation rate).

  The drying speed increases as the difference between the temperature of the slurry (cake) in the filter chamber 130 and the saturated water vapor temperature corresponding to a predetermined vacuum pressure increases. However, as the drying process starts, the temperature of the cake rapidly decreases due to water evaporation, the temperature difference becomes smaller, and the drying rate decreases. Therefore, the heating speed at the initial stage of the drying process can be maintained (repeated drying) by repeating the operation of immediately heating the cake to a predetermined temperature and then immediately leading to the vacuum (under reduced pressure) a plurality of times.

  Even when the drying process is repeated in this way, the heat medium is circulated at a low pressure, the first switching valve 32A is opened, and the vacuum pump 31 passes through the condenser 33, the vacuum tank 34, and the vacuum line 30 to enter the filter press 501. The filtrate chamber S11 is evacuated. Then, after the temperature of the cake in the filter chamber 130 is lowered by a predetermined value from the heat medium temperature, the first switching valve 32A is closed. Thereafter, after the temperature of the cake in the filter chamber 130 rises to a predetermined temperature, the first switching valve 32A is opened again, and the filtrate chamber S11 is evacuated by the vacuum pump 31. Such an operation is repeated a predetermined number of times.

[Blow process]
The blowing process can be performed at an arbitrary timing (after completion of filtration in the dehydration process, after completion of the drying process, or the like). In the blow process, the air valve 41 and the slurry discharge valve 51 are opened, compressed air is supplied to the filter press 1 via the blow line 40, and the slurry is discharged via the slurry discharge line 50.

  FIG. 10 is a cross-sectional view showing a main part of a filter press 601 in the fifth embodiment of the present invention. As shown in FIG. 10, the filter press 601 uses the second filter plate 310 (FIGS. 7A and 7B) in the second embodiment instead of the filter plate 110 in the fourth embodiment. This is different from the filter press 501 of the fourth embodiment. Since the other points of the filter press 601 are the same as those of the filter press 501 of the above-described fourth embodiment, description thereof is omitted.

  FIG. 11 is a cross-sectional view showing a main part of a filter press 701 in the sixth embodiment of the present invention. As shown in FIG. 11, the filter press 701 uses the filter plate 410 (FIGS. 8A and 8B) in the third embodiment in place of the filter plate 110 in the fourth embodiment. This is different from the filter press 501 of the embodiment. Since the other configuration of the filter press 701 is the same as that of the filter press 501 of the fourth embodiment, the description thereof is omitted.

  FIG. 12 is a schematic diagram showing a dehydration drying apparatus according to the seventh embodiment of the present invention. As shown in FIG. 12, this dehydrating and drying apparatus has the same configuration as the dehydrating and drying apparatus shown in FIG. 1, but the dehydrating and drying apparatus shown in FIG. 12 is described below as the dehydrating and drying apparatus shown in FIG. It is different in point. That is, the filtrate discharge line 35 for discharging the filtrate discharged from the filter chamber in the filter press 1 is connected to the first filtrate discharge line 35A connected to a part of the plurality of filtrate chambers and the remaining filtrate chamber. The second filtrate discharge line 35B is provided, and a third switching valve (open / close valve) 32C is provided in the second filtrate discharge line 35B. When the slurry in the filter chamber is squeezed by the heat medium, the volume of the filter chamber decreases. Thereby, the slurry in the filter chamber is dehydrated to form a cake. As the slurry is dehydrated, the filtrate is discharged from the filter chamber, and the filtrate is discharged to the outside of the dehydrating and drying apparatus via the first filtrate discharge line 35A and the second filtrate discharge line 35B.

  When the filter chamber of the filter press 1 is evacuated by the vacuum pump 31, the first switching valve 32A and the third switching valve 32C are opened, and the second switching valve 32B is closed. When discharging the filtrate from the filter chamber, the first switching valve 32A is closed and the second switching valve 32B and the third switching valve 32C are opened. Further, by opening the second switching valve 32B and the third switching valve 32C, the pressure in the filter chamber in the filter press 1 can be instantaneously guided from vacuum to atmospheric pressure.

  A compressor (not shown) that generates compressed air is connected to the blow line 40. Thus, compressed air is blown from the compressor into the filter chamber via the blow line 40, and the slurry remaining in the filter press 1 and the slurry supply port of the filter chamber is discharged through the slurry discharge line 50 by this compressed air. It is like that. The blow line 40 is branched in the middle, and includes a first blow line 40A connected to the filter press 1 and a second blow line 40B connected to the second filtrate discharge line 35B. A first air valve 41A is provided in the first blow line 40A, and a second air valve 41B is provided in the second blow line 40B. The slurry discharge line 50 is provided with a slurry discharge valve 51.

  A slurry dehydration drying process using the dehydration drying apparatus having such a configuration will be described. The slurry dehydration drying process in the present embodiment includes a slurry dehydration process by slurry filtration and squeezing, a drying process for drying the slurry after dehydration, and a blowing process for blowing the slurry after dehydration or drying, And a venting step for allowing pressurized gas to pass through the filter chamber.

[Dehydration process]
(1) Filtration First, the slurry is supplied to the filter press 1 by the slurry supply pump 11 via the slurry supply line 10, the slurry supply valve 12, and the slurry pressure detector 14, and filled in the filter chamber 130. When the slurry is further supplied to the filter chamber 130, the water in the slurry becomes a filtrate and is discharged from the filtrate chambers S 1 and S 11 through the filtrate discharge passages 106 and 116 through the filtrate discharge line 35.

  The slurry supply pressure may be set to a low pressure of, for example, an absolute pressure of 0.15 MPa to 0.20 MPa at the start of filtration, gradually increased as the filtration proceeds, and finally set to an absolute pressure of 0.6 MPa or more. preferable. In addition, it is preferable to select an optimum value for the filtration time depending on the properties of the slurry.

  The slurry may be preheated before being supplied to the filter press 1 (preliminary warming filtration). In this case, by supplying the heated slurry to the filter press 1, the filterability of the slurry can be improved. In parallel with the filtration, the heat medium heated in the heating tank 26 is circulated and supplied to the heat medium chambers S2 and S12 in the filter press 1 through the heat medium circulation lines 20A and 20B by the heat medium circulation pump 21. The slurry may be warmed (warm filtration). In this case, the filterability of the slurry can be improved by filtering while heating the slurry.

(2) Squeeze Next, the heat medium heated by the heat medium circulation pump 21 is supplied to the heat medium chambers S2 and S12 in the filter press 1 through the heat medium circulation line 20A. The slurry in the chamber 130 is heated by the heat medium. The heat medium returns to the heating tank 26 via the heat medium circulation line 20B, the second heat medium temperature detector 23, and the heat medium pressure detector 24, and is heated by the heating tank 26. It is supplied again to the heat medium chambers S2 and S12 in the filter press 1 through the circulation line 20A.

  The pressure (squeezing pressure) of the heat medium in the heat medium chamber S2 is adjusted to a predetermined value by the back pressure valve 25 provided in the heat medium circulation line 20B. When the heat medium is supplied to the heat medium chamber S2, the diaphragm 102 of the first filter plate 100 expands toward the filter chamber 130, whereby the slurry in the filter chamber 130 is squeezed and heated at the same time. The water in the slurry becomes pressed filtrate and is discharged from the filtrate chambers S1 and S11 through the filtrate discharge passages 106 and 116 through the filtrate discharge line 35, respectively.

  Thus, by filtering and pressing the slurry, the slurry is dehydrated and gradually becomes a cake. In this dehydration step, dehydration may be performed only by filtration without squeezing.

  In addition, the opening valve 3 (refer FIG. 1) may be opened temporarily at the time of pressing start, and the gas accumulated in heat-medium chamber S2, S12 may be discharged | emitted. Moreover, it is preferable that the pressing pressure with respect to a slurry can be adjusted within the range of absolute pressure 0.1MPa (atmospheric pressure) to 1.6MPa. The squeezing pressure is gradually increased after the start of squeezing and is preferably set to a slurry supply pressure or higher and 1.6 MPa or lower. The temperature of the heat medium is not particularly limited as long as it is equal to or higher than the saturated vapor temperature corresponding to the vacuum pressure, but is preferably 70 ° C or higher. In this way, the slurry is heated to a set temperature higher than a predetermined saturated steam temperature (saturated steam temperature corresponding to the vacuum pressure).

[Drying process]
In the drying step, the heat medium is circulated in the filter press 1 in the same manner as in the squeezing in the dehydration step, but the pressure of the heat medium adjusted by the back pressure valve 25 is preferably set lower than the squeezing pressure at the time of squeezing. . Simultaneously with the start of the drying process, the first switching valve 32A and the third switching valve 32C are opened, and the filtrate chambers S1, S11 in the filter press 1 by the vacuum pump 31 through the condenser 33, the vacuum tank 34, and the vacuum line 30. Is evacuated and the slurry is brought to vacuum pressure. During the squeezing process, the vacuum pump 31 is operated in advance to depressurize the inside of the vacuum tank 34, and simultaneously with the start of the drying process, the first switching valve 32A and the third switching valve 32C are opened to instantly vacuum the filtrate chambers S1, S11. It can also be.

  During the above-described pressing, the slurry in the filter chamber 130 is sufficiently heated by the heat medium. Since the temperature difference between the set temperature of the slurry and the saturated steam temperature corresponding to the vacuum pressure is large, the slurry in the filter press 1 is instantaneously guided under the vacuum pressure in the drying process, so that the heat supplied by the heat medium is reduced. In addition, the thermal energy held by the slurry is used for evaporation. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate (evaporation rate).

  The efficiency of the vacuum pump 31 can be increased by supplying the coolant to the condenser 33 and returning the steam generated from the slurry (cake) in the filter chamber 130 to water. The vacuum pressure in the drying process is preferably an absolute pressure of 0.03 MPa or less. When the set temperature is 100 ° C. or higher, which is a saturated steam temperature corresponding to atmospheric pressure, the first switching valve 32A is kept closed after the drying process is started, and the second switching valve 32B and the third switching valve are kept. Vapor generated from the slurry by opening the valve 32C can be discharged from the filtrate discharge line 35 instead of from the vacuum line 30. Also in this case, the slurry in the filter chamber 130 is sufficiently heated during the squeezing, and the difference between the set temperature of the slurry and the saturated steam temperature corresponding to the atmospheric pressure is large, so that the thermal energy possessed by the slurry is evaporated. Used. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate.

  The drying speed increases as the difference between the temperature of the slurry (cake) in the filter chamber 130 and the saturated water vapor temperature corresponding to a predetermined vacuum pressure increases. However, as the drying process starts, the temperature of the cake rapidly decreases due to water evaporation, the temperature difference becomes smaller, and the drying rate decreases. Therefore, the heating speed at the initial stage of the drying process can be maintained (repeated drying) by repeating the operation of immediately heating the cake to a predetermined temperature and then immediately leading to the vacuum (under reduced pressure) a plurality of times.

  Even when the drying process is repeated in this way, the heat medium is circulated at a pressure lower than the pressing pressure, the first switching valve 32A and the third switching valve 32C are opened, and the condenser 33, the vacuum tank 34, and the vacuum line 30 are opened. The filtrate chambers S1 and S11 in the filter press 1 are evacuated by the vacuum pump 31. Then, after the temperature of the cake in the filter chamber 130 is lowered by a predetermined value from the heat medium temperature, the first switching valve 32A is closed. Thereafter, after the temperature of the cake in the filter chamber 130 rises to a predetermined temperature, the first switching valve 32A is opened again, and the filtrate chambers S1 and S11 are evacuated by the vacuum pump 31. Such an operation is repeated a predetermined number of times.

[Blow process]
A blow process can be performed at arbitrary timings (after completion | finish of pressing of a dehydration process, after completion | finish of a drying process, etc.). In the blowing process, the first air valve 41A and the slurry discharge valve 51 are opened, the first switching valve 32A, the second switching valve 32B, the third switching valve 32C, and the second air valve 41B are closed, and the first blow line 40A is opened. Compressed air is supplied to the filter press 1 via the slurry discharge line 50, and the slurry is discharged via the slurry discharge line 50.

[Ventilation process]
An aeration process can be performed at arbitrary timings (after completion | finish of filtration of a dehydration process or after completion | finish of pressing, during a drying process, or after a drying process). In the drying process, the aeration process may be performed several times during the process. The aeration performed after the completion of the filtration in the dehydration process has the effect of mainly discharging moisture remaining in the slurry in the filter chamber 130, and the aeration performed after the completion of the drying process is mainly dried in the filter chamber 130 to cause cracks. There is an effect of further drying the cake having an increased surface area. As the pressurized gas to be supplied, any one of steam, air, dehumidified air, and warm exhaust gas can be used.

The aeration process is divided into the following two types according to the method of a pressurized gas aeration.
(A) Pressurized gas is supplied into the filter chamber 130 from the first blow line 40 </ b> A, and moisture or vapor in the filter chamber 130 is discharged through the filtrate discharge passages 106 and 116. At this time, the first air valve 41A, the second switching valve 32B, and the third switching valve 32C are opened, and the second air valve 41B, the first switching valve 32A, and the slurry discharge valve 51 are closed. In other words, the first blow line 40 </ b> A and the filtrate discharge line 35 constitute a ventilation mechanism that allows the pressurized gas to pass through the filter chamber 130.
(B) The pressurized gas is supplied from the second blow line 40B to the filtrate chambers S1 and S11 through the second filtrate discharge line 35B, and this pressurized gas is supplied to the filter chamber 130 through the filter cloth. Further, moisture or vapor in the filter chamber 130 is discharged through the first filtrate discharge line 35A. At this time, the second air valve 41B and the first switching valve 32A are opened, and the first air valve 41A, the second switching valve 32B, the third switching valve 32C, and the slurry discharge valve 51 are closed. At this time, the vacuum pump 31 is driven to evacuate the filtrate chambers S1 and S11. That is, the second blow line 40B, the second filtrate discharge line 35B, and the first filtrate discharge line 35A constitute a ventilation mechanism that allows the pressurized gas to pass through the filter chamber 130.

  When the vacuum pump 31 is not driven, the second air valve 41B and the second switching valve 32B may be opened, and the first air valve 41A, the third switching valve 32C, and the slurry discharge valve 51 may be closed.

The end point of filtration and pressing in the dehydration step, the end point of the drying step, or the switching timing to the subsequent step can be performed based on a preset time, but can also be detected by the following method.
(1) End point of filtration in the dehydration step: Detecting a time point when the amount of solids injected into the filter chamber 130 reaches a predetermined value.
(2) End point of squeezing in the dehydration step: When the pressure in the filter chamber 130 falls below the squeezing pressure by the heat medium, when the flow rate of the squeezed filtrate or the amount of squeezed filtrate reaches a predetermined value, or within the filter chamber 130 The time when the temperature of the cake reaches a predetermined value is detected.
(3) End point of drying process: detecting temperature change of cake in filter chamber 130, temperature change of heating medium, or temperature change of filtrate discharge passages 106, 116.
In this embodiment, the filter press described in the second to sixth embodiments can be used in place of the filter press 1.

  Next, an example of a slurry dehydration drying process when the filter press 501 shown in FIG. 9 is used in the dehydration drying apparatus according to the present embodiment will be described. The slurry dehydrating and drying process in this example includes a dehydrating process for dewatering the slurry by filtering the slurry, a drying process for drying the slurry after dehydration, a blowing process for blowing the slurry after dehydration or drying, and a filter chamber. And an aeration process for allowing the pressurized gas to pass therethrough.

[Dehydration process (filtration)]
First, the slurry is supplied to the filter press 501 by the slurry supply pump 11 via the slurry supply line 10, the slurry supply valve 12, and the slurry pressure detector 14, and filled in the filter chamber 130. When the slurry is further supplied to the filter chamber 130, the water in the slurry becomes a filtrate, which is discharged from the filtrate chamber S 1 through the filtrate discharge passage 116 through the filtrate discharge line 35.

  The slurry supply pressure may be set to a low pressure of, for example, an absolute pressure of 0.15 MPa to 0.20 MPa at the start of filtration, gradually increased as the filtration proceeds, and finally set to an absolute pressure of 1.6 MPa or more. preferable. In addition, it is preferable to select an optimum value for the filtration time depending on the properties of the slurry.

  Note that the slurry may be preheated before being supplied to the filter press 501 (preliminary warming filtration). In this case, by supplying the heated slurry to the filter press 501, the filterability of the slurry can be improved. In parallel with the filtration, the heat medium heated in the heating tank 26 is circulated and supplied to the heat medium chamber S12 in the filter press 501 by the heat medium circulation pump 21 through the heat medium circulation lines 20A and 20B. May be warmed (warm filtration). In this case, the filterability of the slurry can be improved by filtering while heating the slurry.

[Drying process]
In the drying process, when the slurry is not heated at the time of filtration, the heat medium heated in the heating tank 26 is circulated and supplied to the heat medium chamber S12 in the filter press 501, and the temperature of the slurry is set to a predetermined vacuum pressure. Heat until the temperature is higher than the saturated water vapor temperature corresponding to. When heating is performed during filtration, the first switching valve 32A and the third switching valve 32C are opened simultaneously with the start of the drying process, and the filter is filtered by the vacuum pump 31 via the condenser 33, the vacuum tank 34, and the vacuum line 30. The filtrate chamber S11 in the press 501 is evacuated to introduce the slurry to the vacuum pressure. During the filtration process, the vacuum pump 31 is operated in advance to depressurize the inside of the vacuum tank 34, and simultaneously with the start of the drying process, the first switching valve 32A and the third switching valve 32C are opened to instantly evacuate the filtrate chamber S11. You can also.

  The slurry in the filter chamber 130 is sufficiently heated by the heat medium. Since the temperature difference between the set temperature of the slurry and the saturated steam temperature corresponding to the vacuum pressure is large, the slurry in the filter press 501 is instantaneously brought under the vacuum pressure in the drying process, so that the heat supplied by the heat medium is reduced. In addition, the thermal energy held by the slurry is used for evaporation. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate (evaporation rate).

  The drying speed increases as the difference between the temperature of the slurry (cake) in the filter chamber 130 and the saturated water vapor temperature corresponding to a predetermined vacuum pressure increases. However, as the drying process starts, the temperature of the cake rapidly decreases due to water evaporation, the temperature difference becomes smaller, and the drying rate decreases. Therefore, the heating speed at the initial stage of the drying process can be maintained (repeated drying) by repeating the operation of immediately heating the cake to a predetermined temperature and then immediately leading to the vacuum (under reduced pressure) a plurality of times.

  Even when the drying process is repeated in this manner, the heat medium is circulated at a low pressure, the first switching valve 32A and the third switching valve 32C are opened, and the vacuum pump is passed through the condenser 33, the vacuum tank 34, and the vacuum line 30. The filtrate chamber S11 in the filter press 501 is evacuated by 31. Then, after the temperature of the cake in the filter chamber 130 is lowered by a predetermined value from the heat medium temperature, the first switching valve 32A is closed. Thereafter, after the temperature of the cake in the filter chamber 130 rises to a predetermined temperature, the first switching valve 32A is opened again, and the filtrate chamber S11 is evacuated by the vacuum pump 31. Such an operation is repeated a predetermined number of times.

[Blow process]
The blowing process can be performed at an arbitrary timing (after completion of filtration in the dehydration process, after completion of the drying process, or the like). In the blowing process, the first air valve 41A and the slurry discharge valve 51 are opened, the first switching valve 32A, the second switching valve 32B, the third switching valve 32C, and the second air valve 41B are closed, and the first blow line 40A is opened. Compressed air is supplied to the filter press 501 and the slurry is discharged via the slurry discharge line 50.

[Ventilation process]
The aeration process can be performed at any timing (after completion of filtration in the dehydration process, during the drying process, or after the drying process). In the drying process, the aeration process may be performed several times during the process. As the ventilation step, any of the above-described method (A) and method (B) may be used.

  FIG. 13 is a schematic diagram showing a dehydration drying apparatus according to the eighth embodiment of the present invention. As shown in FIG. 13, this dehydrating and drying apparatus has the same configuration as the dehydrating and drying apparatus shown in FIG. 1, but the dehydrating and drying apparatus shown in FIG. 13 is described below as the dehydrating and drying apparatus shown in FIG. It is different in point. That is, the vacuum line 30 for evacuating the filter chamber in the filter press 1 is provided with a first switching valve (open / close valve) 32A and three vacuum tanks 34A, 34B, 34C. Although FIG. 13 shows an example in which three vacuum tanks are provided in parallel, the number of vacuum tanks is not limited to three, and any number may be used as long as it is two or more. The vacuum line 30, the vacuum pump 31, the first switching valve 32 </ b> A, and the vacuum tanks 34 </ b> A, 34 </ b> B, 34 </ b> C constitute a pressure reducing mechanism for compressing the slurry in the filter chamber in the filter press 1.

  As shown in FIG. 13, a cooling mechanism 33 for cooling these vacuum tanks 34A, 34B, and 34C is provided. A cooling liquid is supplied to the cooling mechanism 33, and the steam guided from the filter press 1 to the cooling mechanism 33 is condensed by exchanging heat with the cooling liquid in the cooling mechanism 33, and is condensed as a condensed liquid from the cooling mechanism 33. It is supposed to be discharged.

  The vacuum tank 34A is condensed by a vacuum pump valve 36A that opens and closes between the vacuum pump 31 and the vacuum tank 34A, a filter press valve 37A that opens and closes between the filter press 1 and the vacuum tank 34A, and a cooling mechanism 33. And a condensed water discharge valve 38A for discharging the condensed water. Similarly, the vacuum tank 34B includes a vacuum pump valve 36B, a filter press valve 37B, and a condensed water discharge valve 38B. The vacuum tank 34C includes a vacuum pump valve 36C, a filter press valve 37C, and a condensed water discharge valve. 38C. The vacuum pump 31 and the vacuum tanks 34A, 34B, 34C are each provided with a pressure measuring device (not shown). Moreover, the volume of each vacuum tank 34A, 34B, 34C is about 5 to 20 times, more preferably about 5 to 10 times the volume of the pipe from the filter press 1 to the first switching valve 32A.

  As shown in FIG. 13, a filtrate discharge line 35 is connected to the vacuum line 30. The filtrate discharge line 35 discharges the filtrate discharged from the filter chamber in the filter press 1 as the slurry is dehydrated. The filtrate discharge line 35 is provided with a second switching valve (open / close valve) 32B. When the slurry in the filter chamber is squeezed by the heat medium, the volume of the filter chamber decreases. Thereby, the slurry in the filter chamber is dehydrated to form a cake. As the slurry is dehydrated, the filtrate is discharged from the filter chamber, and this filtrate is discharged to the outside of the dehydrating and drying apparatus via the filtrate discharge line 35.

  When discharging the filtrate from the filter chamber, the first switching valve 32A is closed and the second switching valve 32B is opened. Further, by opening the second switching valve 32B, the pressure in the filter chamber in the filter press 1 can be instantaneously guided from vacuum to atmospheric pressure.

  A compressor (not shown) that generates compressed air is connected to the blow line 40. Thus, compressed air is blown from the compressor into the filter chamber via the blow line 40, and the slurry remaining in the filter press 1 and the slurry supply port of the filter chamber is discharged through the slurry discharge line 50 by this compressed air. It is like that. The blow line 40 is provided with an air valve 41, and the slurry discharge line 50 is provided with a slurry discharge valve 51.

  A slurry dehydration drying process using the dehydration drying apparatus having such a configuration will be described. The slurry dehydration drying process in this embodiment includes a dehydration process for slurry dehydration by slurry filtration and squeezing, a drying process for drying the slurry after dehydration, and a blowing process for blowing the slurry after dehydration or drying. Have.

[Dehydration process]
(1) Filtration First, the slurry is supplied to the filter press 1 by the slurry supply pump 11 via the slurry supply line 10, the slurry supply valve 12, and the slurry pressure detector 14, and filled in the filter chamber 130. When the slurry is further supplied to the filter chamber 130, the water in the slurry becomes a filtrate and is discharged from the filtrate chambers S 1 and S 11 through the filtrate discharge passages 106 and 116 through the filtrate discharge line 35.

  The slurry supply pressure may be set to a low pressure of, for example, an absolute pressure of 0.15 MPa to 0.20 MPa at the start of filtration, gradually increased as the filtration proceeds, and finally set to an absolute pressure of 0.6 MPa or more. preferable. In addition, it is preferable to select an optimum value for the filtration time depending on the properties of the slurry.

  The slurry may be preheated before being supplied to the filter press 1 (preliminary warming filtration). In this case, by supplying the heated slurry to the filter press 1, the filterability of the slurry can be improved. In parallel with the filtration, the heat medium heated in the heating tank 26 is circulated and supplied to the heat medium chambers S2 and S12 in the filter press 1 through the heat medium circulation lines 20A and 20B by the heat medium circulation pump 21. The slurry may be warmed (warm filtration). In this case, the filterability of the slurry can be improved by filtering while heating the slurry.

(2) Squeeze Next, the heat medium heated by the heat medium circulation pump 21 is supplied to the heat medium chambers S2 and S12 in the filter press 1 through the heat medium circulation line 20A. The slurry in the chamber 130 is heated by the heat medium. The heat medium returns to the heating tank 26 via the heat medium circulation line 20B, the second heat medium temperature detector 23, and the heat medium pressure detector 24, and is heated by the heating tank 26. It is supplied again to the heat medium chambers S2 and S12 in the filter press 1 through the circulation line 20A.

  The pressure (squeezing pressure) of the heat medium in the heat medium chamber S2 is adjusted to a predetermined value by the back pressure valve 25 provided in the heat medium circulation line 20B. When the heat medium is supplied to the heat medium chamber S2, the diaphragm 102 of the first filter plate 100 expands toward the filter chamber 130, whereby the slurry in the filter chamber 130 is squeezed and heated at the same time. The water in the slurry becomes pressed filtrate and is discharged from the filtrate chambers S1 and S11 through the filtrate discharge passages 106 and 116 through the filtrate discharge line 35, respectively.

  Thus, by filtering and pressing the slurry, the slurry is dehydrated and gradually becomes a cake. In this dehydration step, dehydration may be performed only by filtration without squeezing.

  It is preferable that the pressing pressure on the slurry can be adjusted within the range of the absolute pressure of 0.1 MPa (atmospheric pressure) to 1.6 MPa. The squeezing pressure is gradually increased after the start of squeezing and is preferably set to a slurry supply pressure or higher and 1.6 MPa or lower. The temperature of the heat medium is not particularly limited as long as it is equal to or higher than the saturated vapor temperature corresponding to the vacuum pressure, but is preferably 70 ° C or higher. In this way, the slurry is heated to a set temperature higher than a predetermined saturated steam temperature (saturated steam temperature corresponding to the vacuum pressure).

[Drying process]
In the drying step, the heat medium is circulated in the filter press 1 in the same manner as in the squeezing in the dehydration step, but the pressure of the heat medium adjusted by the back pressure valve 25 is preferably set lower than the squeezing pressure at the time of squeezing. . Here, it is preferable that each vacuum tank 34A, 34B, 34C is depressurized to a predetermined pressure, preferably an absolute pressure of 0.03 MPa or less, more preferably 0.02 MPa or less, during squeezing in the dehydration step. For example, the vacuum tanks 34A, 34B, 34C and the vacuum pump 31 can be operated as shown in Table 1 below.

  As shown in Table 1, the vacuum pump valves 36A, 36B, 36C and the filter press valves 37A, 37B, 37C of the vacuum tanks 34A, 34B, 34C are opened, and the first switching valve 32A and the vacuum tanks 34A, 34B, 34C are condensed. Water discharge valves 38A, 38B, and 38C are closed. In this state, the vacuum pump 31 and the cooling mechanism 33 are driven (preparation). After the vacuum pump 31 or each of the vacuum tanks 34A, 34B, 34C reaches the set pressure, the vacuum pump valves 36A, 36B, 36C and the filter press valves 37A, 37B, 37C of the vacuum tanks 34A, 34B, 34C are closed, and the vacuum The pump 31 is stopped (set pressure). Immediately after the start of the drying process, the vacuum 1 state in Table 1 is set, and thereafter, the vacuum 2 state to the vacuum 5 state are repeated. The inside of the filter press 1 may be decompressed by continuously driving the vacuum pump 31 without switching the opening and closing of each valve.

  During the above-described pressing, the slurry in the filter chamber 130 is sufficiently heated by the heat medium. Since the temperature difference between the set temperature of the slurry and the saturated steam temperature corresponding to the vacuum pressure is large, the slurry in the filter press 1 is instantaneously guided under the vacuum pressure in the drying process, so that the heat supplied by the heat medium is reduced. In addition, the thermal energy held by the slurry is used for evaporation. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate (evaporation rate).

  The efficiency of the vacuum pump 31 can be increased by supplying the cooling liquid to the cooling mechanism 33 and returning the steam generated from the slurry (cake) in the filter chamber 130 to water. When the set temperature is 100 ° C. or higher, which is a saturated steam temperature corresponding to atmospheric pressure, the first switching valve 32A is kept closed after the drying process is started, and the second switching valve 32B is opened to make a slurry. It is also possible to exhaust the vapor generated from the filtrate from the filtrate discharge line 35 instead of from the vacuum line 30. Also in this case, the slurry in the filter chamber 130 is sufficiently heated during the squeezing, and the difference between the set temperature of the slurry and the saturated steam temperature corresponding to the atmospheric pressure is large, so that the thermal energy possessed by the slurry is evaporated. Used. Therefore, the self-evaporation of the water contained in the slurry is accelerated and bumping occurs, thereby increasing the drying rate.

  The drying speed increases as the difference between the temperature of the slurry (cake) in the filter chamber 130 and the saturated water vapor temperature corresponding to a predetermined vacuum pressure increases. However, as the drying process starts, the temperature of the cake rapidly decreases due to water evaporation, the temperature difference becomes smaller, and the drying rate decreases. Therefore, the heating speed at the initial stage of the drying process can be maintained (repeated drying) by repeating the operation of immediately heating the cake to a predetermined temperature and then immediately leading to the vacuum (under reduced pressure) a plurality of times.

  Even when the drying process is repeated in this manner, the heat medium is circulated at a pressure lower than the pressing pressure, the first switching valve 32A is opened, and the filtrate chambers S1 and S11 in the filter press 1 are evacuated. Then, after the temperature of the cake in the filter chamber 130 is lowered by a predetermined value from the heat medium temperature, the first switching valve 32A is closed. Thereafter, after the temperature of the cake in the filter chamber 130 rises to a predetermined temperature, the first switching valve 32A is opened again, and the filtrate chambers S1 and S11 are evacuated by the vacuum pump 31. Such an operation is repeated a predetermined number of times.

[Blow process]
A blow process can be performed at arbitrary timings (after completion | finish of pressing of a dehydration process, after completion | finish of a drying process, etc.). In the blow process, the air valve 41 and the slurry discharge valve 51 are opened, compressed air is supplied to the filter press 1 via the blow line 40, and the slurry is discharged via the slurry discharge line 50.

The end point of filtration and pressing in the dehydration step, the end point of the drying step, or the switching timing to the subsequent step can be performed based on a preset time, but can also be detected by the following method.
(1) End point of filtration in the dehydration step: Detecting a time point when the amount of solids injected into the filter chamber 130 reaches a predetermined value.
(2) End point of squeezing in the dehydration step: When the pressure in the filter chamber 130 falls below the squeezing pressure by the heat medium, when the flow rate of the squeezed filtrate or the amount of squeezed filtrate reaches a predetermined value, or within the filter chamber 130 The time when the temperature of the cake reaches a predetermined value is detected.
(3) End point of drying process: detecting temperature change of cake in filter chamber 130, temperature change of heating medium, or temperature change of filtrate discharge passages 106, 116.

  In the present embodiment, an example in which three vacuum tanks 34A, 34B, and 34C are provided has been described, but the number of vacuum tanks is not limited to this. For example, by not discharging condensed water in the vacuum tank, the same effect as described above can be obtained by two vacuum tanks.

  Moreover, in this embodiment, it can replace with the filter press 1 and the filter press described in the 2nd and 3rd embodiment mentioned above can also be used.

  As described above, according to the present invention, slurry can be dehydrated and dried with the minimum amount of energy used and in a short time, and the peelability of the cake can be improved.

  In each of the above-described embodiments, the example in which the slurry supply pipe 121 is provided in the center of the fixed plate 120A and the opening is provided in the center of each filter plate has been described. However, the present invention is not limited to this. For example, the filter press can be configured to supply slurry from above or below the filter plate.

[Example 1]
Experiments were performed using the dehydration drying apparatus shown in FIG. Experimental conditions and experimental results are shown in Table 2 below. With reference to Table 2, the drying effect when the slurry that has reached a predetermined temperature is guided under a low pressure, and the drying effect when heating and vacuum drying are repeated will be described.

  As shown in Table 2, sludge containing a large amount of organic matter having a concentration of 33 g / L and a loss on ignition of 68% was used as a test slurry. Moreover, the time of the drying process was calculated | required from the time when the moisture content of a dry cake will be 40% by experiment.

  In Experimental Example 1, warm water was used as a heat medium, and the vacuum pump 31 and the condenser 33 were operated only during the drying process. In Experimental Example 2, hot water is used as a heat medium, the vacuum pump 31 and the condenser 33 are operated only during the drying process, and the first switching valve 32A is opened and closed several times during the drying process, and the vacuum line 30 and the filter are operated. Press 1 was disconnected intermittently. In the comparative example, warm water was used as the heat medium, and the vacuum pump 31 and the condenser 33 were operated in the press dehydration process and the drying process.

In the comparative example, since the vacuum drying was performed through the pressing dehydration process and the drying process, the temperature of the slurry (cake) remained at 53 ° C. The drying was performed under the condition that the saturated steam temperature corresponding to the vacuum pressure was 48 ° C., and the temperature difference between the cake temperature and the saturated steam temperature was 5 ° C. The drying time until the moisture content of the dried cake reached 40% was 52 minutes, and the filtration rate was 0.64 kg · m ⁻² · h ⁻¹ .

  In Experimental Example 1, since the vacuum drying was not performed in the press dehydration step, the temperature of the slurry (cake) at the end of the press dehydration step reached 89 ° C. In the drying process, since the vacuum drying is in progress, the cake temperature was lowered from 89 ° C to 53 ° C. The drying was performed under the condition that the saturated steam temperature corresponding to the vacuum pressure was 48 ° C., and the temperature difference between the cake temperature and the saturated steam temperature was in the range of 5 ° C. to 41 ° C.

The drying time until the moisture content of the dried cake reached 40% was 46 minutes, and the filtration rate was 0.67 kg · m ⁻² · h ⁻¹ . The filtration rate was 1.05 times that of the comparative example. Further, the power of the vacuum pump 31 and the condenser 33 during the drying process was 64% of the comparative example.

  According to Experimental Example 1, the slurry can be heated in the squeezing and dehydrating process, and the filter press 1 can be immediately evacuated in the drying process to give the slurry sufficient heat energy. The self-evaporation was accelerated and the drying could be completed in a shorter time.

  In Experimental Example 2, since the vacuum drying was not performed in the press dehydration process, the temperature of the slurry (cake) at the end of the press dehydration process reached 89 ° C. In the drying process, in order to prevent the cake temperature from being lowered due to vacuum drying, the vacuum line 30 is closed by the first switching valve 32A when the cake temperature falls to 78 ° C., and the cake temperature rises to 88 ° C. again. The vacuum line 30 was opened by the first switching valve 32A. The time and number of times that the vacuum line 30 was opened were 2 minutes and 8 times, respectively, and the time and number of times that the vacuum line 30 was closed were 2 minutes and 7 times, respectively.

By repeating the heating and vacuum drying of the cake, the cake temperature is maintained within a range of 78 ° C. to 88 ° C., and the cake temperature and the saturated steam temperature are compared with the saturated steam temperature of 48 ° C. corresponding to the vacuum pressure. The drying was performed within a temperature difference of 30 ° C. to 40 ° C. The drying time until the moisture content of the dried cake reached 40% was 30 minutes, and the filtration rate was 0.78 kg · m ⁻² · h ⁻¹ . The filtration rate was 1.22 times that of the comparative example. The power of the vacuum pump 31 and the condenser 33 during the drying process was 42% of the comparative example.

  According to Experimental Example 2, the acceleration of self-evaporation due to the cake having sufficient thermal energy is maintained by repeating the operation of heating the cake in the drying process and immediately evacuating the filter press 1 several times. The drying could be completed in a shorter time.

[Example 2]
Experiments were performed using a dehydrating and drying apparatus having a filter press 501 shown in FIG. As a comparative example, a filter press in which a plurality of filter plates 100 shown in FIGS. 4A and 4B are arranged in parallel was used.

As a test slurry, sludge containing a large amount of organic matter having a concentration of 28 g / L and a loss on ignition of 78% was used. In the experimental example of the present invention, a filter press having a filtration area of 3.45 m ² and a filtration chamber volume of 34 L was used, and in the comparative example, a filter press having a filtration area of 3.45 m ² and a filtration chamber volume of 50 L was used.

The basic conditions in this experiment are as follows.
[Dehydration process (filtration)]
Comparative example: sludge supply pressure 0.6 MPa, filtration time 30 minutes, sludge supply amount 210 L
Experimental example: Sludge supply pressure from 0.1 to 1.6 MPa in order, filtration time 45 minutes, sludge supply volume 210L
[Pressing process]
Comparative example only: pressing pressure 1.6 MPa, pressing time 30 minutes [drying step]
Comparative example: heat medium pressure 0.13 MPa, vacuum pressure 0.01 MPa
Experimental example: heat medium pressure 0.13 MPa, vacuum pressure 0.01 MPa

In the comparative example, the time for the drying process was determined from the time when the moisture content of the dried cake was 55% by continuous experiments. As a result, in continuous operation, the drying time to reach a moisture content of about 55% was 70 minutes. The filtration rate at this time is 0.68 kg / m ² · h.

In repeating the operation in the experimental example of the present invention, the slurry is set to 80 ° C., the first switching valve 32A is opened, the filter chamber is maintained at 0.01 MPa for 5 minutes, and then the first switching valve 32A is closed. Was repeated 6 times. The operation results are shown in Table 3 below.

  From the results shown in Table 3, although the filtration time is increased by 15 minutes in the experimental example of the present invention, the heat transfer speed is improved because both heat transfer surfaces of the filter chamber are metal, and the drying speed by repeating self-evaporation is increased. The improvement shortened the drying time by 11 minutes. Furthermore, the time required for the whole process was shortened by 26 minutes by omitting the pressing time. As a result, the filtration rate was higher than that of the comparative example, and a filtration rate of 1.32 times that of the comparative example was obtained. The reason why the filtration pressure was gradually increased to 0.1 to 1.6 MPa and the filtration chamber volume was set to 34 L is to increase the concentration of slurry at the end of filtration. Also, if the heating medium is circulated and supplied during filtration or during filtration to heat the slurry to the set temperature, the heating time during drying can be shortened by 10 minutes, and the filtration rate is increased.

  The test sludge is an organic sludge having a high compressibility, but in the case of an inorganic sludge having a low compressibility, the sludge may shrink with drying. In order to keep the heat transfer, it is necessary that the cake and the heat transfer surface always contact each other. In this case, the expansion / contraction part 412 is provided on the heat transfer member 112 like the filter plate 410 in the sixth embodiment shown in FIG. If it is provided to give stretchability and the heat transfer surface is always in contact with the cake, operation can be performed without reducing efficiency.

[Example 3]
Experiments were performed using the dehydration drying apparatus shown in FIG. As a test slurry, sludge containing a large amount of organic matter having a concentration of 28 g / L and a loss on ignition of 78% was used. In this experiment, a filter press having a filtration area of 3.45 m ² and a filtration chamber volume of 50 L was used.

The basic conditions in this experiment are as follows.
[Dehydration process (filtration)]
Sludge supply pressure 0.6 MPa, filtration time 30 minutes, sludge supply volume 210L
[Dehydration process (press)]
Pressing pressure 1.6 MPa, pressing time 30 minutes [drying step]
Heat medium pressure 0.13 MPa
The time of the drying process was determined from the time when the moisture content of the dried cake was 55% by continuous experiments. As a result, in the operation of continuously vacuuming in the drying step, the drying time for the cake water content to reach about 55% was 70 minutes, and the filtration rate was 0.68 kg / m ² · h.

As an experimental example of the present invention, when the set temperature T1 is 80 ° C. and T1 = 80 ° C., the first switching valve 32A is opened, and the temperature difference between the inlet temperature T3 and the outlet temperature T4 of the heat medium becomes 1 ° C. At that time, the first switching valve 32A was closed. The operation results at this time are shown in Table 4 below.

From the results shown in Table 4, in the experimental example of the present invention, the drying time when the moisture content of the cake reaches about 55% is 34 minutes shorter than the case of continuous vacuum heating in which the vacuum is continuously vacuumed in the drying process. The speed was 0.90 kg / m ² · h. Thus, according to the experimental example of the present invention, it can be seen that a filtration rate of 1.32 times that in the case of continuously making a vacuum in the drying process was obtained, and an efficient and energy-saving operation was realized.

[Example 4]
Under the same conditions as in Example 3, the first switching valve 32A was opened and closed at regular intervals to perform self-evaporation of the slurry. The operation results at this time are shown in Table 5 below.

From the results shown in Table 5, even when the first switching valve 32A is opened and closed at regular intervals, the drying time is 29 minutes shorter than that in the case of continuous vacuum heating, 41 minutes, and the filtration rate is 0.78 kg / m ² · h. It became. Thus, according to the experimental example of the present invention, it can be seen that a filtration rate of 1.14 times that in the case of continuously making a vacuum in the drying step was obtained, and an efficient and energy-saving operation was realized.

[Example 5]
Experiments were performed using the dehydration drying apparatus shown in FIG. Experimental conditions and experimental results are shown in Table 6 below. With reference to Table 6, the drying effect when the slurry that has reached a predetermined temperature is guided under a low pressure, and the drying effect when heating and vacuum drying are repeated will be described.

As shown in Table 6, sludge containing a large amount of organic matter having a concentration of 33 g / L and a loss on ignition of 68% was used as a test slurry. In this experiment, a filter press having a filtration area of 3.45 m ² was used. Moreover, the time of the drying process was calculated | required from the time when the moisture content of a dry cake will be 40% by experiment.

The basic conditions in this experiment are as follows.
[Dehydration process]
Sludge supply pressure 0.6 MPa, filtration time 30 minutes, sludge supply volume 136L
[Pressing process]
Pressing pressure 1.6 MPa, pressing time 20 minutes [drying step]
Heat medium pressure 0.13 MPa

[Ventilation process]
In the experimental example of the present invention, after completion of the drying process, pressurized gas is supplied from the second blow line 40B to the filtrate chambers S1 and S11 through the second filtrate discharge line 35B, and this pressurized gas is supplied through the filter cloth. Supply to the filter chamber 130. Further, moisture or vapor in the filter chamber 130 is discharged through the first filtrate discharge line 35A. At this time, the second air valve 41B and the first switching valve 32A are opened, and the first air valve 41A, the second switching valve 32B, the third switching valve 32C, and the slurry discharge valve 51 are closed. At this time, the vacuum pump 31 is driven to evacuate the filtrate chambers S1 and S11. The flow rate of pressurized air was 100 L / min and aerated for 4 minutes.

  In Comparative Example 1, warm water was used as the heat medium, and the vacuum pump 31 and the condenser 33 were operated in the press dehydration process and the drying process. In Comparative Example 2 and the experimental example of the present invention, hot water is used as a heat medium, the vacuum pump 31 and the condenser 33 are operated only in the drying process, and the first switching valve 32A is opened and closed several times during the drying process. The vacuum line 30 and the filter press 1 were disconnected intermittently.

In Comparative Example 1, since the vacuum drying was performed through the pressing dehydration process and the drying process, the temperature of the slurry (cake) remained at 53 ° C. The drying was performed under the condition that the saturated steam temperature corresponding to the vacuum pressure was 48 ° C., and the temperature difference between the cake temperature and the saturated steam temperature was 5 ° C. The drying time until the moisture content of the dried cake reached 40% was 52 minutes, and the filtration rate was 0.64 kg · m ⁻² · h ⁻¹ . Moreover, the dry cake adhered to the filter cloth and the metal heat transfer member, and did not peel from the filter cloth and the heat transfer member by its own weight.

  In Comparative Example 2, since the vacuum drying was not performed in the press dehydration step, the temperature of the slurry (cake) at the end of the press dehydration step reached 89 ° C. In the drying process, in order to prevent the cake temperature from being lowered due to vacuum drying, the vacuum line 30 is closed by the first switching valve 32A when the cake temperature falls to 78 ° C., and the cake temperature rises to 88 ° C. again. The vacuum line 30 was opened by the first switching valve 32A. The time and number of times that the vacuum line 30 was opened were 2 minutes and 8 times, respectively, and the time and number of times that the vacuum line 30 was closed were 2 minutes and 7 times, respectively.

By repeating the heating and vacuum drying of the cake, the cake temperature is maintained within a range of 78 ° C. to 88 ° C., and the cake temperature and the saturated steam temperature are compared with the saturated steam temperature of 48 ° C. corresponding to the vacuum pressure. The drying was performed within a temperature difference of 30 ° C. to 40 ° C. The drying time until the moisture content of the dried cake reached 40% was 30 minutes, and the filtration rate was 0.78 kg · m ⁻² · h ⁻¹ , and the filtration rate was 1.22 times that of Comparative Example 1. . The power of the vacuum pump 31 and the condenser 33 during the drying process was 42% of the comparative example.

  According to the experimental example of the present invention, acceleration of self-evaporation due to the cake having sufficient thermal energy is achieved by repeating the operation of heating the cake in the drying process and immediately evacuating the filter press 1 a plurality of times. It was maintained and drying could be completed in a shorter time. Further, since cracks occurred in the dried cake, the dried cake did not adhere to the filter cloth and the heat transfer member, and peeled off from the filter cloth and the heat transfer member by its own weight.

In the experimental example of the present invention, the behavior of the drying process was the same as that of Comparative Example 1 and Comparative Example 2, and thus the same behavior was exhibited. In the experimental example of the present invention, the drying time until the dry cake moisture content reached 40% was 20 minutes, the ventilation time was 4 minutes, and the filtration rate was 0.83 kg · m ⁻² · h ⁻¹ . The drying process was completed in a time shorter than 30 minutes.

  In the case of sludge containing a large amount of organic matter, when drying proceeds, heat transfer becomes worse and the drying rate is reduced. Therefore, efficient drying can be performed by switching to the aeration process when the drying speed starts to decrease.

[Example 6]
An experiment was conducted using the filter press 501 shown in FIG. 9 in the dehydrating and drying apparatus shown in FIG. Experimental conditions and experimental results are shown in Table 7 below. As a test slurry, sludge containing a large amount of organic matter having a concentration of 28 g / L and a loss on ignition of 78% was used. In this experiment, a filter press having a filtration area of 3.45 m ² and a filtration chamber volume of 34 L was used.

The basic conditions in this experiment are as follows.
[Dehydration process (filtration)]
The sludge supply pressure was gradually increased from 0.1 MPa to 1.6 MPa.
The filtration time was 45 minutes and the sludge supply amount was 153L.
[Drying process]
The heat medium pressure was 0.13 MPa, the heat medium temperature was 80 ° C., and the vacuum pressure was 100 MPa.
[Ventilation process]
In the comparative example, the ventilation process was not performed.

In the experimental example of the present invention, dehumidified air was supplied to the filtrate chamber through the second filtrate discharge line 35B at an air flow rate of 100 L / min for 4 minutes and discharged through the first filtrate discharge line 35A.
In the comparative example, the drying time was 60 minutes, the moisture content of the cake was 55%, and the filtration rate was 0.60 kg · m ⁻² · h ⁻¹ , whereas in the experimental example of the present invention, the drying rate was 40 minutes and the aeration time was 4 minutes, the moisture content of the cake was 54%, and the filtration rate was 0.68 kg · m ⁻² · h ⁻¹ . Thus, sludge was able to be dried in a shorter time by performing the aeration process mentioned above.

[Example 7]
Experiments were performed using the dehydrating and drying apparatus shown in FIG. The conditions of the apparatus are as follows.
-Filtration area: 3.5 m ²
・ Filter chamber volume: 50L
・ Piping volume: 6L
・ Vacuum pump displacement: 50 L / min
・ Vacuum tank: 60L × 3 for the experimental example of the present invention, 60L × 1 for the comparative example
・ Set pressure of vacuum tank: 5kPa
-Pressure corresponding to a predetermined saturated steam temperature: 10 kPa
The experimental method is as follows.
・ Sludge concentration: 30 g / L
・ Loss on ignition: 23%
-Filtration: 0.6 MPa, 30 minutes- Fixed object driving amount: 4.5 kg
・ Compression: 1.6 MPa, 20 minutes

Under such conditions, the time (drying time) at which the moisture content of the cake was 40% was measured in the drying step. In both the experimental example and the comparative example of the present invention, the vacuum tank was depressurized in advance during the dehydration step. In the experimental example of the present invention, the first switching valve 32A was opened and closed every other minute, and the valves were operated as shown in Table 8. The vacuum pump was continuously driven after vacuum 3 in Table 8. In the comparative example, the vacuum pump was continuously driven from the time of pressing in the dehydration step, and the first switching valve 32A was opened and closed every other minute. The results are as shown in Table 8 below.

  In the comparative example, the drying time until the moisture content of the cake reached 40% took 46 minutes, and 2.5 kg of water was recovered from the vacuum tank. In the comparative example, since there is only one vacuum tank, the water condensed in the vacuum tank cannot be discharged, so that it re-evaporates and the vacuum tank is not sufficiently depressurized within a predetermined time. The pressure could not be reduced sufficiently, resulting in a longer drying time.

  In the experimental example of the present invention, the drying time until the moisture content of the cake reached 40% was 30 minutes. In the experimental example of the present invention, the pressure reduction of the filter press, the discharge of the condensed water, and the pressure reduction of the vacuum tank were simultaneously performed on the three vacuum tanks, and these were repeated sequentially, so that the inside of the filter press The pressure could be reduced and the drying time was shortened.

  While one embodiment of the invention has been illustrated and described, it will be readily appreciated that various changes and modifications can be made without departing from the scope of the claims.

  INDUSTRIAL APPLICABILITY The present invention is suitably used for a dehydrating and drying apparatus for dehydrating and drying slurry such as sludge discharged from water and sewage systems, wastewater treatment facilities in rural villages, human waste treatment facilities and industrial drainage facilities.

FIG. 1 is a schematic diagram showing a dehydration drying apparatus according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a filter press in the dehydration drying apparatus of FIG. FIG. 3 is a side view showing a first filter plate included in the filter press of FIG. 2. 4A is a cross-sectional view taken along line AA in FIG. 4B is a cross-sectional view taken along line BB in FIG. 5A and 5B are cross-sectional views of a second filter plate included in the filter press of FIG. FIG. 6 is a cross-sectional view showing the main part of the filter press in the second embodiment of the present invention. 7A and 7B are cross-sectional views illustrating a second filter plate included in the filter press of FIG. 8A and 8B are sectional views showing a filter plate in the third embodiment of the present invention. FIG. 8C is a partially enlarged view of FIG. 8B. FIG. 9 is a cross-sectional view showing a main part of a filter press in the fourth embodiment of the present invention. FIG. 10 is a cross-sectional view showing a main part of a filter press in the fifth embodiment of the present invention. FIG. 11: is sectional drawing which shows the principal part of the filter press in the 6th Embodiment of this invention. FIG. 12 is a schematic diagram showing a dehydration drying apparatus according to the seventh embodiment of the present invention. FIG. 13 is a schematic diagram showing a dehydration drying apparatus according to the eighth embodiment of the present invention.

Claims (29)

A first filter plate including a filter cloth, a diaphragm, and a heat medium chamber; a second filter plate including a filter cloth, a metal heat transfer member, and a heat medium chamber; and the first filter plate and the first filter plate. Placed so as to form a filter chamber between the two filter plates,
Supplying slurry to the filter chamber;
Filtering the slurry in the filter chamber with the filter cloth of the first filter plate and the second filter plate;
Supplying a heat medium to the heat medium chamber formed in the first filter plate and pressing the diaphragm of the first filter plate against the slurry in the filter chamber;
Supplying a heat medium to the heat medium chamber formed on the second filter plate, and transferring heat of the heat medium to the slurry through the heat transfer member of the second filter plate;
After heating the slurry to a set temperature higher than a predetermined saturated steam temperature, the slurry is led to a pressure corresponding to the predetermined saturated steam temperature, and a temperature difference between the set temperature and the predetermined saturated steam temperature A method for dewatering and drying a slurry, wherein the water in the slurry is self-evaporated. Heating the slurry from the time of filtration or pressing,
The slurry dehydration drying method according to claim 1, wherein the self-evaporation of water in the slurry is repeated a plurality of times. A filter plate provided with a filter cloth, a metal heat transfer member and a heat medium chamber, respectively, is arranged so as to form a filter chamber between the filter plates,
Supplying slurry to the filter chamber;
Filter the slurry in the filter chamber through the filter cloth of the filter plate,
Supplying a heat medium to a heat medium chamber formed in the filter plate, and transferring heat of the heat medium to the slurry through a heat transfer member of the filter plate;
After heating the slurry to a set temperature higher than a predetermined saturated steam temperature, the slurry is led to a pressure corresponding to the predetermined saturated steam temperature, and a temperature difference between the set temperature and the predetermined saturated steam temperature A method for dewatering and drying a slurry, wherein the water in the slurry is self-evaporated. Heating the slurry during the filtration, during the filtration, or after the filtration is completed,
4. The slurry dehydrating and drying method according to claim 3, wherein the self-evaporation of water in the slurry is repeated a plurality of times.   During the filtration, during the squeezing, after the filtration, after the squeezing, during the self-evaporation of the water of the slurry and after the self-evaporation of the water of the slurry, a pressurized gas is passed through the filter chamber. The slurry dehydration drying method according to any one of claims 1 to 4, wherein the slurry is dehydrated and dried. In the passage of the pressurized gas into the filter chamber,
Supplying the pressurized gas to the filter chamber through a blow line for blowing pressurized gas into the filter chamber;
The slurry dehydration drying method according to claim 5, wherein the pressurized gas is discharged from the filter chamber through a filtrate discharge line for discharging the filtrate from the filter chamber. In the passage of the pressurized gas into the filter chamber,
Supplying the pressurized gas to the filter chamber through at least one of a plurality of filtrate discharge lines for discharging filtrate from the filter chamber;
The slurry dehydration drying method according to claim 5, wherein the pressurized gas is discharged from the filter chamber through at least one of the plurality of filtrate discharge lines.   5. The self-evaporation of water in the slurry is repeated a plurality of times by sequentially connecting the filter chambers to a plurality of vacuum tanks maintained at a pressure corresponding to the predetermined saturated steam temperature or less. The method for dehydrating and drying a slurry according to any one of the above. Measure the physical property value according to the temperature of the slurry in the filter chamber,
The slurry dehydration drying method according to any one of claims 1 to 4, wherein the start and stop of the self-evaporation of water in the slurry is controlled based on the physical property value. As the physical property values, the temperature of the slurry in the filter chamber, the temperature difference between the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber are measured,
In the control of the start and stop of the self-evaporation of water in the slurry,
When the measured temperature of the slurry in the filter chamber is equal to or higher than a predetermined value, the self-evaporation of water in the slurry is started,
The self-evaporation of water in the slurry is stopped when a temperature difference between the measured inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber reaches a predetermined value. The method for dehydrating and drying a slurry according to claim 9. As the physical property value, a temperature difference between the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber is measured,
When the measured temperature difference between the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber reaches a predetermined value, self-evaporation of water in the slurry is started and stopped. The method for dehydrating and drying a slurry according to claim 9. As the physical property value, the temperature difference between the inlet temperature of the heat medium chamber supplying the heat medium and the outlet temperature of the heat medium chamber is measured,
In the control of the start and stop of the self-evaporation of water in the slurry,
When the temperature difference between the measured inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber reaches a predetermined value, self-evaporation of the water in the slurry is started, and after the elapse of a certain time, the slurry The slurry dehydrating and drying method according to claim 9, wherein self-evaporation of water is stopped. As the physical property values, the temperature of the filtrate discharged from the filter chamber, the temperature difference between the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber are measured,
In the control of the start and stop of the self-evaporation of water in the slurry,
When the measured temperature of the filtrate discharged from the filter chamber reaches a predetermined value or more, the self-evaporation of water in the slurry is started,
When the measured temperature difference between the inlet temperature of the heat medium chamber and the outlet temperature of the heat medium chamber reaches a predetermined value, or after a predetermined time has elapsed since the self-evaporation of the water of the slurry, 10. The slurry dehydrating and drying method according to claim 9, wherein the self-evaporation is stopped. As the physical property value, the temperature of the slurry in the filter chamber is measured,
In the control of the start and stop of the self-evaporation of water in the slurry,
When the measured temperature of the slurry in the filter chamber reaches a predetermined value or more, self-evaporation of water in the slurry is started, and self-evaporation of water in the slurry is stopped after a predetermined time has elapsed. The method for dehydrating and drying a slurry according to claim 9.   The slurry dehydration drying method according to any one of claims 1 to 4, wherein the start and stop of the self-evaporation of water in the slurry are repeated a plurality of times at regular intervals. The temperature difference between the set temperature and the predetermined saturated steam temperature is in the range of 20 ° C to 70 ° C,
The slurry dehydration drying method according to any one of claims 1 to 4, wherein the pressure corresponding to the predetermined saturated steam temperature is an absolute pressure of 0.03 MPa or less. A first filter plate comprising: a diaphragm; a filter cloth disposed between the diaphragm and the filter chamber; and a heat medium chamber that presses the diaphragm toward the filter chamber by a supplied heat medium; A metal heat transfer member having a surface, a filter cloth disposed between the heat transfer surface of the heat transfer member and the filter chamber, and heat supplied from the heat transfer medium to the slurry through the heat transfer surface. A second filter plate comprising a heat transfer medium chamber for transmission; and a filter press having at least one filter chamber sandwiched between the first filter plate and the second filter plate;
A heating mechanism for heating the slurry to a set temperature higher than a predetermined saturated steam temperature;
A decompression mechanism that instantaneously guides the slurry heated by the heating mechanism to a pressure corresponding to the predetermined saturated steam temperature;
A slurry dehydrating and drying apparatus comprising: The second filter plate includes a resin frame at a peripheral edge portion of the heat transfer surface of the heat transfer member,
The slurry dehydrating and drying apparatus according to claim 17, wherein the heat transfer member of the second filter plate is formed integrally with the frame. A heat transfer member made of metal having a heat transfer surface, a filter cloth disposed between the heat transfer surface and the filter chamber, and heat transmitted to the slurry through the heat transfer surface. A filter plate each having a medium chamber; and a filter press having at least one filter chamber formed between the filter plates;
A heating mechanism for heating the slurry to a set temperature higher than a predetermined saturated steam temperature;
A decompression mechanism that instantaneously guides the slurry heated by the heating mechanism to a pressure corresponding to the predetermined saturated steam temperature;
A slurry dehydrating and drying apparatus comprising: The filter plate is provided with a resin frame at the peripheral edge of the heat transfer surface of the heat transfer member,
The slurry dehydrating and drying apparatus according to claim 19, wherein the heat transfer member of the filter plate is formed integrally with the frame.   21. The slurry dehydrating and drying apparatus according to claim 17, further comprising a ventilation mechanism that allows pressurized gas to pass through the filter chamber.   The aeration mechanism supplies the pressurized gas to the filter chamber via a blow line for blowing pressurized gas into the filter chamber and discharges the filtrate from the filter chamber via the filtrate discharge line. The slurry dehydrating and drying apparatus according to claim 21, wherein gas is discharged from the filter chamber.   The aeration mechanism supplies the pressurized gas to the filter chamber through at least one of a plurality of filtrate discharge lines for discharging filtrate from the filter chamber, and at least one other of the plurality of filtrate discharge lines. The slurry dehydrating and drying apparatus according to claim 21, wherein the pressurized gas is discharged from the filter chamber. The decompression mechanism is
(I) a plurality of vacuum tanks maintained below a pressure corresponding to the predetermined saturated steam temperature and connected in parallel to the filter chamber of the filter press;
(Ii) a plurality of valves for switching connection between the plurality of vacuum tanks and the filter chamber of the filter press;
With
21. The slurry dehydrating and drying apparatus according to claim 17, wherein the plurality of vacuum tanks have a cooling mechanism. At least one detector for measuring a physical property value according to the temperature of the slurry in the filter chamber;
21. The slurry dehydrating and drying apparatus according to claim 17, wherein the pressure reducing mechanism is controlled based on a physical property value measured by the at least one detector.   The slurry dehydrating and drying apparatus according to claim 25, wherein the at least one detector includes a detector for measuring a temperature of the slurry in the filter chamber.   26. The at least one detector includes a first detector that measures an inlet temperature of the heat medium chamber, and a second detector that measures an outlet temperature of the heat medium chamber. The slurry dehydrating and drying apparatus according to 1.   The slurry dehydrating and drying apparatus according to claim 25, wherein the at least one detector includes a detector for measuring a temperature of the filtrate discharged from the filter chamber. The temperature difference between the set temperature and the predetermined saturated steam temperature is in the range of 20 ° C to 70 ° C,
21. The slurry dehydrating and drying apparatus according to claim 17, wherein a pressure corresponding to the predetermined saturated steam temperature is 0.03 MPa or less.

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