JP2005238051A - Heating type filter press and its dewatering and drying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating type filter press, and filtering method with improved heat efficiency and peelability of cake, by improving a heating plate heating a filter chamber and combining vacuum suction with it. <P>SOLUTION: In this heating type filter press with the filter chamber formed by the heating plate 5 and a diaphragm filter plate, and a filter cloth suspended in the filter chamber, filter beds 43 having protrusions are provided on resin core plates 32 with a heating passage formed on the surface, and heating plates 5 are composed by extending metal heating plates 33 formed with recessed grooves on the rear faces of the protrusions, and a heating device of the heating plates 5 and a decompression unit of the filter chamber are provided. The metal heating plate 33 is made thin to improve a heat conductivity to the filter chamber and reduce heat radiation loss. A mechanism of the heating plate 5 is simple, allowing easy manufacturing, increasing strength of the metal heating plates 33, and easy assembling. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a filter press suitable for treatment of clean water sludge, sewage sludge, industrial wastewater sludge, etc., in particular, by improving the heating plate for heating the filtration chamber, improving the sludge properties of the filtration chamber of the filter press, The present invention relates to a heated filter press that combines vacuum suction as needed to dehydrate and dry cakes in a filtration chamber.

  In recent water purification facilities and sewage treatment plants, the capacity of wastewater treatment facilities has declined due to deterioration of the quality of raw water. In addition, the disposal method of cakes has become a problem due to the decrease in final disposal sites, and research on volume reduction and effective use of cakes is urgently needed. 2. Description of the Related Art Conventionally, a filter press to which a pressurizing force is applied has been widely adopted as a solid-liquid separator. A filter press using a diaphragm filter plate can be used even for cakes with poor filterability, but the dehydrator alone cannot be completely removed even if the internal retained water in the cake is squeezed. In order to efficiently remove the water, an apparatus for indirectly heating the cake by increasing the temperature inside the filter press has been proposed. For example, in Patent Document 1, a heat conductive panel having a heating chamber is disposed on a resin filter plate, and a pressure reducing device is provided in a filtration chamber constituted by the filter plate and a diaphragm filter plate to heat and suck the cake. Discloses an apparatus for reducing the moisture content of a dehydrated cake.

JP 2000-334222 A (Claim 8 and Claim 10, paragraph number 0024 to paragraph number 0026, FIG. 4)

  An apparatus that heats a dehydrated cake with a conventional heating jacket and depressurizes the filtration chamber to reduce moisture in the cake has an advantage of drying quickly because of its high thermal conductivity. Increasing the degree of vacuum lowers the boiling point and makes it easier for the water in the cake to evaporate. However, the heating jacket attached to the surface of the filter plate becomes relatively large and the heat loss also increases. The jacket-type heating device is complicated and difficult to manufacture, and the scale of the heating jacket cannot be confirmed, making cleaning difficult. The dehydration method of supplying the stock solution while heating the filtration chamber is because the heat energy is discharged together with the filtrate, the heat conduction efficiency to the cake becomes worse, the drying time becomes longer, and the expected result is not obtained. .

  This invention simplifies the metal filter medium to improve heat transfer efficiency and devise a heating / depressurization method. The heating plate is constructed by stretching a metal heating plate on a heat insulating resin core plate. Provided is a heating type filter press incorporating a heating means from the time and using vacuum suction as necessary to improve the thermal efficiency and the peelability of the cake, and the filtration method therefor.

  The gist of the present invention is to form a filtration chamber by alternately arranging heating plates and diaphragm filter plates, disposing a heating device on the heating plate, and suspending a pair of filter cloths in the filtration chamber, A heating plate is formed by stretching a metal heating plate on a resin core plate having a heating channel formed on the surface, and a heating channel supply hole and a discharge hole are provided in the peripheral portion of the resin core plate. With the connection, the filtration chamber is heated to change the properties of the organic matter in the sludge, and the viscosity and specific resistance of the concentrated sludge are lowered to improve the dewaterability. In particular, the filterability of the cake on the filter cloth surface on the heating plate side where the water content decreases and the water permeability becomes poor improves the thermal efficiency and the peelability of the cake. The diaphragm filter plate enables high-pressure squeezing of cake and uses compressed water, so there is no deterioration due to heat.

  It is a filtration bed that has a large number of protrusions on the surface of the metal heating plate that constitutes the heating plate and forms a filtrate groove. The heat transfer area to the filtration bed is widened, the heating efficiency is improved, and the filtrate is discharged. A flow path is also secured. The metal heating plate to be stretched on the resin core plate is preferably processed to form a protrusion on the filtration bed of the metal heating plate and a concave groove on the back surface of the protrusion. The heat conduction efficiency to the filtration bed is improved and the heat radiation loss is reduced. The mechanism is simple and easy to manufacture, and the strength of the metal heating plate is increased by forming. Since the metal filter plate is simply attached to the core plate, assembly is also easy.

  If a vacuum suction device is connected to the filtrate discharge passage communicating with the filtration chamber at the peripheral edge of the heating plate or diaphragm filter plate, the filtration chamber is decompressed to lower the boiling point, thereby lowering the evaporation temperature of moisture in the cake. be able to. The generated wet air and water droplets remaining on the filter surface of the filter cloth or diaphragm filter plate can be discharged. A cake with reduced dehydration time and low moisture content can be obtained. The heating plate and diaphragm filter plate that form the filtration chamber have a concave surface that is approximately symmetrical, so the viscosity and specific resistance of the concentrated sludge are reduced, even in difficult-to-filter cakes, and the filterability and peelability are improved. The resulting cake becomes a structure suitable for short-time processing using a filter cloth traveling filter press, and large-capacity processing is possible.

  The metal heating plate stretched on the resin core plate may be covered up to the concave slope of the support floor of the resin core plate, enabling heating from the entire concave surface of the heating plate, and heat conduction efficiency Is improved and the cake can be dried uniformly. The resin core plate forming the filtration chamber may be a heating plate by stretching a metal heating plate on a flat support floor. The entire heating plate is flat, and the entire cake on one side is heated with metal. The plates can be touched and dried evenly. The dried cake with improved dewaterability can be discharged simply by vibrating the filter cloth, and is suitable for a filter press with a fixed filter cloth. Instead of using a filter cloth on the diaphragm filter plate side, a flat heating plate and a smooth concave diaphragm filter plate are used to form a filtration chamber, and a filter cloth is hung on the front surface of the heating plate. The plate may be brought into direct contact with the cake. The cake is plastically deformed and peeled off from the diaphragm, and the cake can be discharged by its own weight. There are fewer components and production costs are lower.

  Instead of the diaphragm filter plate, a filter plate may be used, which is suitable for a stock solution containing a large amount of inorganic matter having good filterability, and is suitable for a large volume treatment. In addition, a heating plate may be formed by stretching a concave metal heating plate on a resin core plate formed in a concave shape, and the filter plate may be formed in a flat plate shape. And the cake can be peeled off by its own weight. Then, without using a filter cloth, a filtration chamber is formed by the flat heating plate and the concave filter plate, and a wedge wire is stretched on the support floor of the filter plate, and the cake is directly attached to the heating plate and the filter plate. The cake may directly contact the heating plate to improve the heat conduction efficiency, and the cake can be dried in a short time. The wedge wire, which is a metal filter medium, does not deteriorate even when heated, has good peelability, and does not deteriorate the filtration characteristics even if it is not washed.

  The dehydration drying method using the heating filter press described above forms a filtration chamber by alternately arranging a heating plate with a metal heating plate stretched over a resin core plate and a diaphragm filter plate with a diaphragm stretched over the core plate. In a cake dehydrating and drying apparatus in which a pair of filter cloths are suspended in the filtration chamber and a heating device and a decompression device for the filtration chamber are provided, a stock solution having a pressure of 0.3 to 0.5 MPa is added to the filtration chamber. After injecting for 360 minutes to concentrate the stock solution, while supplying concentrated sludge in the filtration chamber with a squeezing pressure of a diaphragm of 0.7 to 1.5 MPa, supplying steam at a heating temperature of 110 ° C. to 120 ° C. and 210 Reduce the boiling point to ~ 160 Torr, continue to heat the cake and depressurize the filtration chamber, and press and dehydrate for 30 to 60 minutes until the cake moisture is close to the limit moisture. While being pressed to change the properties of the organic matter in the sludge, viscosity and resistivity of the concentrated sludge is improved dewatering properties decreases. In particular, the filterability of the cake on the filter cloth surface on the heating plate side where water content is lowered and water permeability is poor is improved, and the cake surface on the heating surface is pulverized and easily peeled off from the heating plate. Furthermore, the suction chamber is depressurized by vacuum suction, the boiling point is lowered, the water is evaporated, and the moisture content in the cake is further reduced. By improving the heat conduction efficiency and the peelability of the cake, a cake having a reduced dehydration time and a low water content can be obtained.

  This invention is configured as described above, and the filtration chamber is formed by a heating plate in which a metal heating plate is stretched on a resin core plate and a diaphragm filter plate or a filter plate, so there is no heat loss like a heating jacket, It becomes a heating body with a small volume. The heating plate mechanism is simple and easy to manufacture, and the structure is not complicated as in the prior art. Since the metal heating plate of the heating plate forms protrusions by molding, it becomes a thin metal heating plate, the heat dissipation area of the heating plate is expanded, and the strength of the metal heating plate is increased. If the metal heating plate is removed from the inside of the heating plate, the attached state of the scale can be confirmed, and it is not difficult to clean the scale or the like unlike the heating jacket.

  The heating filter press according to the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a flowchart of the heating filter press. The filter press 1 according to the present invention includes a horizontal rail 4 and a front frame 2 and a rear frame 3. Are arranged on the horizontal rail 4, and the heating plates 5 and the diaphragm filter plates 6 are alternately arranged in parallel. The parallel heating plates 5 and diaphragm filter plates 6 are connected by a loose device (not shown), and can be opened and closed by a tightening cylinder 7 supported on the rear frame 3. The filter press 1 is provided with a sludge storage tank 9 for supplying a stock solution by a press-fitting pump 8 and a water receiving tank 11 for supplying pressure water to a diaphragm filter plate 6 by a squeezing pump 10. Further, a boiler 12 that supplies steam or high-temperature water to the heating plate 5 and a recovery tank 13 that recovers the heated exhaust heat constitute a circulation circuit via a circulation pump 14. And the vacuum pump 18 is arrange | positioned through the heat exchanger 17 in the filtrate tank 16 which collects the filtrate solid-liquid-separated with the filter press 1. FIG. Reference numeral 19 denotes an on-off valve provided in the steam or high-temperature water circulation circuit, and reference numeral 20 denotes a relief valve.

FIG. 2 is a longitudinal sectional view of a heating plate and a diaphragm filter plate in which a filter cloth is stretched, and a pair of filter cloths 21 and 21 are disposed between the heating plate 5 and the diaphragm filter plate 6. The liquid supply plate 22 is sandwiched and attached to the upper end portions of 21 and 21. Since the filter cloth 21 is brought into direct contact with the heating plate 5, it is made of polyester with high heat resistance. Drive sprockets 23 and 23 are disposed above the heating plate 5 and the diaphragm filter plate 6. A drive chain 24 is connected to the upper ends of the bonded filter cloths 21 and 21. It is hung on either side. A pair of return rolls 25, 25 are arranged below the heating plate 5 and the diaphragm filter plate 6, and the lower ends of the pair of filter cloths 21, 21 are away from the direction approaching the front and rear return rolls 25, 25. Each is hung around.
The lower end portions of the filter cloths 21, 21 adjacent to the front and rear are joined together and connected to the other end of the drive chain 24 wound around the drive sprocket 23.

  When the heating plate 5 and the diaphragm filter plate 6 of FIG. 2 are closed, a filtration chamber 26 is formed between the pair of filter cloths 21 and 21, and when the heating plate 5 and the diaphragm filter plate 6 are opened, the filter cloth 21 is formed. 21 can be raised and lowered in a seesaw shape. Stock solution supply passages 27 and 28 penetrating in the front-rear direction are disposed on the heating plate 5 and the diaphragm filter plate 6, and a liquid supply passage 29 is formed in the liquid supply plate 22. When the heating plate 5 and the diaphragm filter plate 6 are closed, the undiluted solution supply paths 27 and 28 of the heating plate 5 and the diaphragm filter plate 6 are communicated, and the liquid supply path 29 of the liquid supply plate 22 that is sandwiched is passed to the filtration chamber 26. A circuit for supplying the stock solution is formed, and the stock solution supply pressure of the press-fit pump 8 is set to 0.3 to 0.5 MPa. Reference numeral 30 denotes a guide roller of the drive chain.

  FIG. 3 is a front view of the heating plate. In the heating plate 5, a metal heating plate 33 is stretched on the front and back surfaces of a resin core plate 32 having a peripheral edge as a sealing surface 31, and is fixed with screws 34. is there. In this embodiment, the resin core plate 32 is made of polypropylene having excellent chemical resistance and wear resistance and heat retention. FIG. 4 is a front view of the resin core plate, in which a concave support floor 35 is formed inside the sealing surface 31 of the resin core plate 32, and a heating channel 36 of zigzag grooves is formed in the support floor 35. It is. A heating fluid supply hole 37 is provided in the upper sealing surface 31 of the resin core plate 32, and an exhaust heat fluid discharging hole 38 is provided in the lower sealing surface 31. It is. The polypropylene resin core plate 32 serving as the base of the heating plate 5 has good heat insulation and can prevent heat radiation from the peripheral portion of the seal surface 31. In this embodiment, steam or the like is supplied from above and discharged from below, but may be supplied from below and discharged from above. Reference numeral 39 denotes a screw hole for fixing the metal heating plate 33.

  FIG. 5 is a front view of the metal heating plate, and the metal heating plate 33 stretched on the resin core plate 32 is formed into a spherical band shape by pressing a metal excellent in conductivity and plastic deformation such as aluminum or stainless steel. It has been given. In addition, this shaping | molding process is good also as a rectangular shape. As shown in FIG. 6, a large number of protrusions 40 are formed on the surface of the metal plate, and a concave groove 41 is formed on the back surface of the protrusion 40 that has been plastically deformed. Since the metal heating plate 33 is formed by a press, the strength is increased with a thin material, and the manufacture becomes simple. A filtrate groove 42 is formed between a large number of protrusions 40... That are punched on the surface of the metal heating plate 33, and the surface is used as a filtration bed 43. The filter bed 43 of the heating plate 5 has a large heat radiation area, the contact area with the cake is expanded, and the assembly of the heating plate 5 is facilitated. In the embodiment of FIG. 3, the resin core plate 32 is stretched on the plane portion of the support floor 35, but as shown in FIG. 7, the metal heating plate 33 a may be covered up to the concave inclined portion. Thus, the cake can be uniformly dried by heating from the entire concave surface of the heating plate 5. In addition, in the small heating plate 5, a groove process may be given to the back surface of an aluminum or stainless steel plate. Reference numeral 44 denotes a mounting hole for the screw 34.

  As shown in FIG. 3, a supply pipe 45 is attached to the upper supply hole 37 of the heating plate 5, and an exhaust heat pipe 46 is attached to the lower discharge hole 38. A supply pipe 45 and a waste heat pipe 46 of the heating plate 5 are connected to the boiler 12 and the recovery tank 13 shown in FIG. 1, respectively, and steam or high-temperature water heated by a circulation pump 14 directly connected to the boiler 12 is used as a heating plate. 5 to form a circulation path for the heated fluid. Since the resin core plate 32 made of polypropylene is used, the supply temperature is set to 110 to 120 ° C. As shown in FIG. 4, a filtrate discharge passage 47 penetrating back and forth is provided in the lower end side wall of the sealing surface 31 of the resin core plate 32, and the filtrate communicates with the filtrate discharge passage 47 to the surface of the metal heating plate 33. A hole 48 is opened. A squeezed water passage 49 is provided in the lower end side wall of the sealing surface 31 of the resin core plate 32 so as to penetrate back and forth. In addition, the arm 50 supported on the horizontal rail 4 is arrange | positioned at the both shoulder parts of the resin core board 32 of the heating plate 5. As shown in FIG.

  FIG. 8 is a cross-sectional view of a heating plate and a diaphragm filter plate forming a filtration chamber. The diaphragm filter plate 6 has a core plate 53 in which a peripheral portion is an attachment surface 51 and a concave support floor 52 is formed inside thereof. Further, a diaphragm 54 is stretched, and a number of protrusions are provided on the filtration bed 55 on the surface of the diaphragm 54. Pressure water of 0.7 to 1.5 MPa is supplied to the diaphragm filter plate 6 by the squeezing pump 10, and the diaphragm 54 is expanded to squeeze the cake. The diaphragm filter plate 6 has an undiluted solution supply path 28 and a filtrate discharge path 56 penetrating in the front-rear direction above the attachment surface 51 of the diaphragm 54. In order to heat the cake by supplying steam at 110 to 120 ° C. to the heating plate 5, the diaphragm 54 uses heat-resistant rubber or thermoplastic elastomer. Although not shown, a pair of filter cloths 21 and 21 holding the liquid supply plate 22 shown in FIG. 2 are suspended from the front surface of the heating plate 5 and the diaphragm filter plate 6 forming the filtration chamber 26. It is like that.

  When the parallel heating plates 5 ... and diaphragm filter plates 6 ... are closed, the respective stock solution supply paths 27, 28 ... and filtrate discharge paths 47, 56 ... communicate in the front-rear direction. The stock solution having a pressure of 0.3 to 0.5 MPa is supplied to the stock solution supply passages 27, 28... By the press-fit pump 8, the sludge in the filtration chamber 26 is concentrated by the press-fit pressure of the stock solution, The filtrate is discharged from the filtrate discharge passages 47, 56,. The filtrate tank 16 storing the filtrate separated from the filtration chamber 26 is sucked with a vacuum pump 18 so that the filtration chamber is decompressed to 210 to 160 Torr.

  The heating plate 5 changes the properties of the organic matter in the sludge of the filtration chamber 26, reduces the viscosity and specific resistance of the concentrated sludge, and improves the dewaterability. In particular, the filterability of the cake in the vicinity of the filter cloth 21 on the heating plate 5 side where the water content is lowered and the water permeability is poor is improved, and the thermal efficiency and the peelability of the cake are improved. If the filtrate tank 16 of the filtrate separated from the filtration chamber 26 is set to a negative pressure by the vacuum pump 18, the boiling point is lowered and the evaporation temperature of moisture in the cake heated by the heating plate 5 can be lowered. it can. Due to the negative pressure, the evaporated wet air is discharged from the filtration chamber 26, and water droplets remaining on the filter surface of the filter cloth 21 and the diaphragm filter plate 6 are also discharged, thereby drying the cake. Furthermore, the diaphragm filter plate 6 squeezes the cake in the filtration chamber 26 at a pressure of 0.7 to 1.5 MPa, thereby reducing the moisture content in the cake. The dehydration time is shortened and a dry cake with low moisture content is obtained. Since the diaphragm 54 uses compressed water at room temperature, there is no deterioration due to heat.

  FIG. 9 is a longitudinal sectional view of another embodiment of the heating plate forming the filtration chamber. In the heating plate 5a of this embodiment, the resin core plate 32a is formed in a flat plate shape, and the support floor 35a has a figure. A metal heating plate 33 shown in FIG. A heating fluid supply hole 37a is provided in the upper sealing surface 31a of the resin core plate 32a, and an exhaust heat fluid exhausting hole 38a is provided in the lower sealing surface 31a. The heating passage 36a is open at the upper and lower ends. It is. The flat metal heating plate 33 contacts the entire cake, and the cake can be dried evenly. An undiluted solution supply path 27a and a filtrate discharge path 47a penetrating in the front-rear direction are provided in the upper seal surface 31a and the lower seal surface 31a of the resin core plate 32a. The flat plate-shaped heating plate 5a and the resin core plate 32a The plan view has the shape shown in FIGS.

  As shown in FIG. 9, the diaphragm filter plate 6 provided on the heating plate 5a having a flat plate shape uses the diaphragm filter plate 6 shown in FIG. A floor 55 is formed. The drying cake of the filtration chamber 26a formed by the flat heating plate 5a and the concave diaphragm filter plate 6 has improved dehydration, so that the illustration is omitted, but only the filter cloth 21 is vibrated. The cake can be discharged, and the structure is suitable for a filter press with a fixed filter cloth. Since the pressed cake surface is plastically deformed and the properties of the organic matter in the sludge are changed by heating, the cake can be discharged from the filtration chamber 26a by its own weight due to the properties of the stock solution.

  FIG. 10 shows another embodiment of a heating plate and a diaphragm filter plate forming a filtration chamber. In this embodiment, a flat heating plate 5a and a concave core plate 53 shown in FIG. 9 are used. A diaphragm 54a having a smooth surface is stretched around the core plate 53 to form a diaphragm filter plate 6a. A filtration chamber 26b is formed by the diaphragm filter plate 6a and the flat heating plate 5a. A filter cloth 21a may be suspended from the front surface of the heating plate 5a in the filtration chamber 26b so that the diaphragm filter plate 6a directly contacts the cake. The cake is plastically deformed and peeled off from the diaphragm 54a, and the cake can be discharged by its own weight. There are fewer components and production costs are lower.

  FIG. 11 shows another embodiment in which the filtration chamber is composed of a heating plate and a filter plate, in which the diaphragm filter plate 6 in FIG. The filter plate 57 has a concave filtration bed 59 formed on the inner side of the peripheral seal surface 58, and a filtrate supply passage 61 is provided in the upper seal surface 58 and a filtrate discharge passage 61 is provided in the front and rear of the lower seal surface 58. It penetrates through. A filtration chamber 62 is constituted by the heating plate 5 in which the filter plate 57 and the concave filtration bed 43 are formed. Although not shown in FIG. 11, a pair of filter cloths 21, 21 holding the liquid supply plate 22 is suspended in the filtration chamber 62. It can be applied to a stock solution with good filterability and is suitable for a filter cloth traveling type filter press, which enables a large volume treatment of the stock solution.

  FIG. 12 shows another embodiment of the filter plate forming the filtration chamber. The filter plate 57a has a peripheral seal surface 58a and a filter bed 59a formed in a flat plate shape, and the upper seal surface 58a has a stock solution. A filtrate discharge path 61a passes through the supply path 60a and the lower seal surface 58a in the front-rear direction. If the filter chamber 57a is formed by the filter plate 57a and the concave heating plate 5a, and the filter plate 57a is formed in a flat plate shape, the viscosity and specific resistance of the concentrated sludge are lowered, and the filter cloth 21 on the heating plate 5 side is reduced. The peelability of the cake on the surface can be improved. Although the concave metal heating plate 33a of FIG. 7 is used as the metal heating plate of this embodiment, the flat metal heating plate 33 of FIG. 6 may be used. Although it is suitable for a filter cloth fixing type filter press and is not shown, the cake can be discharged if the filter cloth 21 is vibrated. The cake can be discharged from the filtration chamber 62a by its own weight.

  FIG. 13 shows another embodiment of the filter plate forming the filtration chamber. The filter plate 63 forms a concave support floor 65 inside the sealing surface 64 at the peripheral edge, and a wedge wire is formed on the support floor 65. 66 is stretched. An undiluted solution supply path 67 passes through the upper seal surface 64 and a filtrate discharge path 68 passes through the lower seal surface 64 in the front-rear direction. A filter chamber 69 is formed by the filter plate 63 and the flat heating plate 5, and the cake is directly brought into contact with the filter plate 63 and the heating plate 5 without using the filter cloth 21. The wedge wire 66 heated by the heating plate 5 is in direct contact with the cake so that the heat conduction efficiency is high and the dewatered cake can be processed in a short time. The cake in the filtration chamber 69 is easily separated from the wedge wire 66 because the cake surface of the heating surface is powdered. The wedge wire 66, which is a metal filter medium, does not deteriorate even when heated, and the filtration characteristics do not deteriorate even if it is not washed.

  The heating-type filter press is configured as described above. The dehydration drying method using the heating-type filter press will be described in detail with reference to the flowchart of FIG. 14 and FIGS. It is pumped from the sludge storage tank 9 to the filter press 1, flows into the stock solution supply paths 27 and 28 of the heating plate 5 and the diaphragm filter plate 6, and is press-fitted into the filtration chamber 26 via the liquid supply plate 22. The stock solution is pressed into the filtration chamber 26 at a supply pressure of 0.3 to 0.5 MPa for 60 to 360 minutes, depending on the properties, and is subjected to solid-liquid separation with the pair of filter cloths 21 and 21 at the press pressure, and concentrated. Use sludge. The filtrate separated from the filtration chamber 26 is discharged from the filtration plates 43, 55 of the heating plate 5 and the diaphragm filter plate 6 to the filtrate discharge passages 47, 56.

  Next, after the supply of the stock solution is stopped, 0.7 to 1.5 MPa of pressure water is pressed into the diaphragm filter plate 6 from the water receiving tank 11 by the squeezing pump 10, and the concentrated sludge in the filtration chamber 26 is squeezed and dehydrated by the diaphragm 54. And the filtrate is separated. Subsequently, while pressing the cake with the diaphragm filter plate 6, steam having a heating temperature of 110 ° C. to 120 ° C. is supplied from the boiler 12 to the heating plate 5, and the metal heating plate 33 is heated to heat the cake in the filtration chamber 26. It changes the properties of organic matter in the cake, lowers the viscosity and specific resistance of the dehydrated cake, and improves the dewaterability. In particular, the filterability of the cake on the surface of the filter cloth 21 on the heating plate 5 side where the water content is lowered and the water permeability is poor is improved, and the thermal efficiency and the peelability of the cake are improved. The exhaust heat steam or hot water that has heated the filtration chamber 26 is recovered from the heating plate 5 to the recovery tank 13, and is again heated by the boiler 12 to be steam at 110 ° C. to 120 ° C.

  Next, while the temperature of the filtrate in the filtrate tank 16 communicating with the filtration chamber 26 is lowered by the heat exchanger 17, the filtrate is sucked by the vacuum pump 18, and the filtration chamber 26 sucked by the vacuum pump 18 is decompressed to 210 to 160 Torr. Lower the boiling point and evaporate the water to further reduce the moisture content of the cake. While squeezing the cake in the filtration chamber 26 with the diaphragm filter plate 6, the cake is heated and depressurized to separate and evaporate the moisture, and the cake is dehydrated for 30 to 60 minutes until the cake moisture reaches the limit moisture. A cake having a reduced dehydration time and a low water content can be obtained, and the cake surface of the heating surface is pulverized and easily peeled off from the heating plate 5.

For the purpose of improving the wastewater treatment technology, a dewatering drying test of purified water sludge was performed using a filter press having a heating / depressurizing function shown in the flowchart of FIG. The test machine used was a heating plate in which an aluminum metal heating plate was stretched on a polypropylene resin core plate having a filtration area of 360 ^□ , and a diaphragm filter plate using a thermoplastic elastomer diaphragm. The filter cloth hung in the filtration chamber between the heating plate and the diaphragm filter plate shown in FIG. 14 is made of heat-resistant polyester.

The experimental dehydration drying process was performed in the order of press-fitting, pressing, heating, and vacuum drying.
(1) Press-fit: The press-fit was a pump press-fit with a pressure of 0.5 MPa, and the press-fit time was compared at 60 minutes, 180 minutes, and 360 minutes.
(2) Squeeze: Squeeze was carried out until the pressure was kept at 1.5 MPa and the cake moisture was close to the limit moisture. Moreover, it squeezed with the same pressure during heating and decompression.
(3) Vacuum heating: Steam having a heating temperature of 110 ° C. was supplied from the upper part of the heating plate, and at the same time, the filtration chamber was decompressed to 210 to 160 Torr. The test was conducted in the following three cases.
A. Comparative dehydration test when not heated.
B. Dehydration drying test with simultaneous heating + decompression.
C. Dehydration drying test that starts heating in the middle of press-fitting and performs dehydration drying with simultaneous heating and pressure reduction.

Table 1 shows the experimental results of dewatering and drying the purified water sludge using a filter press having a heating / depressurizing function. Table 2 is a graph of the experimental results in Table 1. The horizontal axis represents the press-fitting time, the left side of the vertical axis represents the filtration rate (Kg / m ² / h), and the right side represents the cake moisture (%). In the case of the structure of this test machine, the metal heating plate is a direct filter plate, so heat conduction is fast, and dehydration is performed using a filter cloth traveling filter press with a short-time processing method and a medium-time processing type filter cloth fixed filter press. In either case, if the concentrated sludge or cake in the filtration chamber is heated, the filtration rate increases and the effect of lowering the cake moisture appears remarkably. Moreover, it turns out that the effect is so large that heating time is long.

  From Table 1 and Table 2, when examining the difference in capacity with respect to the difference in press-in time, when the press-in time of the stock solution is 60 minutes, the cake moisture is 58.9% for non-heated dehydration. The moisture decreased to 26% and to 30.5% by press-fitting heating. Due to the short press-in time of the stock solution, the cake is thin and heat conduction is fast. The heat energy consumed was 1190.3 Kcal when heated in the middle of press-fitting and 480.2 Kcal when heated from the time of pressing. Heating in the middle of press-fitting requires about 2.5 times as much heat energy as the heat energy flows out together with the filtrate and heating from the time of pressing. The filtration rate was small within 10 percent variation regardless of the heating time. Since the cake thickness is as thin as 3 to 5 mm, the dehydration is suitable for a filter cloth traveling type filter press of a short-time processing method.

  When the press-in time of the stock solution is 180 minutes, the heated product has a heating effect for both cake moisture and filtration rate. The heat consumption energy is 2442.9 Kcal when heated in the middle of press-fitting, and is reduced to 529.9 Kcal when heated from the time of pressing. Heating in the middle of press-fitting requires about 4.6 times as much heat energy consumption as heating from the time of pressing. If heating is performed in the middle of press-fitting, the press-fitting efficiency is increased, so there is an advantage of increasing the cake thickness to 6 to 10 mm. However, the filtrate heated with the cake is discharged, and the energy loss of steam increases. In the heating from the time of pressing, there was no significant increase in the consumption of heat energy at the heating time of 60 minutes and 180 minutes. This is because the heating plate heated to 110 ° C. is such that the metal heating plate is in direct contact with the filter cloth, the resin core plate has good heat retention, the cake is squeezed, and the heat energy flows out with the filtrate. This is probably due to the fact that there are few. In heating at the time of pressing, the cake thickness after drying is as thin as 4 to 6 mm, and it is considered that cake peeling is difficult in a filter cloth fixing type that forms a heating plate and a diaphragm filter plate in a concave shape and constitutes a filtration chamber. Either the heating plate or the diaphragm filter plate needs to be formed in a flat plate shape.

When the press-in time is 360 minutes, the filtration rate for the filtration cycle is greatly increased to 3.3 kg / m ² / C with no heating, and the filtration rate due to heating from the middle of press-fitting is greatly increased to 4.9 kg / m ² / C. The result is better than 3.51 Kg / m ² / C with time heating. However, even when heated during pressing, the cake thickness is 5 to 11 mm, the cake thickness by heating is 7 to 11 mm from the middle of the press-fitting, and the cake thickness is approximately equal. The required energy consumption is three times greater than the press-in time of heating at the time of pressing for 180 minutes, but the energy consumption is only 43% as compared with the case of heating from the middle of press-fitting. Since the loss of steam energy is significantly greater than in the case of heating during pressing, it is necessary to study the total energy. When the press-in time is 360 minutes, the cake is easy to peel off and at the same time, both the cake moisture and the filtration speed are effective, and the cake can be easily discharged even with a medium-time treatment type filter cloth fixed filter press.

  For dehydration, we examined dehydration drying using a short-time treatment method and a medium-time treatment method. However, in terms of energy, heating from the time of squeezing is advantageous, and in particular, 60 minutes of a filter cloth traveling filter press with a short-time treatment method. The most advantageous time is pressing. In the case of a filter fixing with a filter cloth of a medium time treatment method, 180 minutes press-fitting is advantageous in that a heating method from the press-fitting is advantageous in order to obtain the cake thickness required for cake peeling, but the energy loss is large. In 360-minute press-fitting, both heating during pressing and heating from the middle of pressing are effective, but from the viewpoint of heat energy, the heating method during pressing is advantageous.

  In the heating type filter press and the filtration method according to the present invention, a metal heating plate with improved heat transfer efficiency is stretched on a resin core plate to constitute a heating plate, and the heating plate and a diaphragm filter plate or a filter plate are used. A filtration chamber is formed, and cake heating and vacuum suction are used in combination, which can reduce energy consumption, improve cake dewaterability, and improve peelability. In recent years, even in the case of water purification facilities and sewage treatment plants, the heated filter press according to the present invention reduces the volume of cake and kills harmful bacteria even when the quality of raw water deteriorates and the number of final disposal sites decreases. Can be used effectively. Therefore, it becomes a heating type filter press suitable for processing of water sludge, sewage sludge, industrial wastewater sludge, and the like, and its dehydration drying method.

It is a flowchart of the heating type filter press which concerns on this invention. Similarly, it is a longitudinal sectional view showing a heating plate and a diaphragm filter plate taken out from a filter press. Similarly, it is a front view of a heating plate. Similarly, it is a front view of a resin core board. Similarly, it is a front view of a metal heating plate. Similarly, it is a side view of a metal heating plate. Similarly, it is a side view of the other Example of a metal heating plate. Similarly, it is a cross-sectional view of a heating plate and a diaphragm filter plate forming a filtration chamber. Similarly, it is a cross-sectional view of another embodiment of a heating plate and a diaphragm filter plate forming a filtration chamber. Similarly, it is a cross-sectional view of another embodiment of a heating plate and a diaphragm filter plate forming a filtration chamber. Similarly, it is a cross-sectional view of another embodiment of the heating plate and the filter plate forming the filtration chamber. Similarly, it is a cross-sectional view of another embodiment of the heating plate and the filter plate forming the filtration chamber. Similarly, it is a cross-sectional view of another embodiment of the heating plate and the filter plate forming the filtration chamber. Similarly, it is a flowchart showing a heating / depressurizing method for a filtration chamber formed by a heating plate and a diaphragm filter plate.

Explanation of symbols

5, 5a, 5b Heating plate 6, 6a Diaphragm filter plate 12 Boiler 18 Vacuum pump 21 Filter cloth 26, 26a, 26b, 69 Filtration chamber 36 Heating flow path 32, 32a Resin core plate 33, 33a Metal heating plate 35, 35a, 65 Support floor 37, 37a Supply hole 38, 38a Discharge hole 40 Protrusion 41 Concave groove 42 Filtrate groove 43, 43a Filtration floor 47, 56 Filtrate discharge channel 53 Core plate 54 Diaphragm 57, 57a, 63 Filter plate 66 Wedge wire

Claims (12)

The filtration plates (26, 26a, 26b) are formed by alternately arranging the heating plates (5, 5a) and the diaphragm filter plates (6, 6a), and the heating device (12) is arranged on the heating plates (5, 5a). In a filter press in which a pair of filter cloths (21, 21) are suspended in a filtration chamber (26, 26a, 26b), a resin core plate (32, 32a) having a heating channel (36) formed on the surface thereof Further, the metal heating plates (33, 33a) are stretched to form the heating plates (5, 5a), and the supply holes (37) of the heating channel (36) are formed in the peripheral portion of the resin core plates (32, 32a). 37a) and a discharge hole (38, 38a), and connected to a heating device (12), a heating type filter press. A large number of protrusions (40) were provided on the surface of the metal heating plate (33, 33a) stretched on the resin core plate (32, 32a) to form a filtration bed (43) forming a filtrate groove (42). The heating type filter press according to claim 1. The metal heating plates (33, 33a) stretched on the resin core plates (32, 32a) are molded, and the projections (40) are formed on the filtration beds (43, 43a) of the metal heating plates (33, 33a). The heated filter press according to claim 1 or 2, wherein a concave groove (41) is formed on the back surface of the projection (40). A vacuum suction device (18) is connected to a filtrate discharge passage (47, 56) communicating with the filtration chamber (26) at a peripheral portion of the heating plate (5) or the diaphragm filter plate (6). The heating type filter press according to any one of claims 1 to 3. The heating type filter press according to any one of claims 1 to 4, wherein the heating plate (5) and the diaphragm filter plate (6) are formed in a concave shape. The metal heating plate (33a) stretched on the resin core plate (32) is formed in a concave shape so as to cover the inclined portion of the support floor (35) of the resin core plate (32). 5. The heating type filter press according to 5. The said resin core board (32a) is formed in flat form, and the heating plate (5a) was comprised by extending | stretching the metal heating plate (33) on the support floor (35a), The 1st thru | or 5 characterized by the above-mentioned. The heating type filter press according to any one of the above. A filtration chamber (26b) is formed by the flat heating plate (5a) and a smooth concave diaphragm filter plate (6a), and a filter cloth (21) is suspended on the front surface of the heating plate (5a). The heated filter press according to claim 7, wherein the diaphragm filter plate (6a) is brought into direct contact with the cake. The heating type filter press according to any one of claims 1 to 7, wherein a filter plate (57, 57a) is used instead of the diaphragm filter plate (6). The metal heating plates (33, 33a) are stretched on the resin core plate (32) formed in the concave shape to constitute the heating plates (5, 5b), and the filter plate (57a) is formed in a flat plate shape. The heating type filter press according to claim 9, wherein the heating type filter press is used. The flat heating plate (5a) and the concave filter plate (63) form a filtration chamber (69), and a wedge wire (66) is stretched on the support floor (65) of the filter plate (63). The heated filter press according to claim 9, wherein the cake is brought into direct contact with the heating plate (5a) and the filter plate (63). A heating plate (5) in which a metal heating plate (33) is stretched on a resin core plate (32) and a diaphragm filter plate (6) in which a diaphragm (54) is stretched on a core plate (53) are alternately arranged in parallel. A filtration chamber (26) is formed, and a pair of filter cloths (21, 21) are suspended in the filtration chamber (26), and a heating device (12) and a decompression device (18) for the filtration chamber (26) are also provided. In the cake dehydrating and drying apparatus, the stock solution having a pressure of 0.3 to 0.5 MPa was pressed into the filtration chamber (26) for 60 to 360 minutes to concentrate the stock solution, and then the concentrated sludge in the filtration chamber (26) was added to the 0.1. While squeezing with a squeezing pressure of a diaphragm (54) of 7 to 1.5 MPa, steam with a heating temperature of 110 ° C. to 120 ° C. is supplied and reduced to 210 to 160 Torr to lower the boiling point, followed by cake heating and filtration While decompressing the chamber (26), Dewatering drying method of heating type filter press wherein the moisture from 30 to 60 minutes squeezed and dewatered to a marginally water.

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