JP4079956B2 - Sludge dehydration drying equipment - Google Patents

Description

  The present invention relates to a sludge dewatering and drying device, and in particular, sludge discharged from water and sewage equipment, rural village drainage equipment, human waste treatment equipment, industrial wastewater treatment equipment, etc. The present invention relates to a dehydration drying apparatus.

Conventionally, in order to dehydrate and dry sludge, it is necessary to install a dewatering device and a drying device in each of them, and the initial cost is high, and it is a fact that a great deal of labor is required for maintenance.
Moreover, what warms and presses sludge at the same time it dries under reduced pressure is known by using warm water as a pressing medium of a pressurization press dehydrator, and decompressing the filter cloth exterior. However, in this device, the thermal conductivity of the squeezed membrane is low, and the distribution of hot water flow between the filter plate and the squeezed membrane and the degree of vacuum between the squeezed membrane and the filter cloth are uneven depending on the location, so the drying time of the cake There are problems such as long and uneven drying.

  An object of the present invention is to provide a sludge dewatering and drying apparatus that solves the above problems, has a squeezed membrane having a thermal conductivity sufficient for heating sludge, and has a short drying time for cakes and does not cause drying unevenness. To do.

One aspect of the present invention is to form a filter chamber composed of a compression membrane and a filter cloth between filter plates, and to heat the sludge in the filter chamber in a sludge dewatering and drying apparatus that compresses and dries the sludge in the filter chamber. A hot water generator for generating hot water is provided, and as the pressing film, a pressing film in which carbon graphite is kneaded with polyurethane resin is used.
Thus, the sludge dehydrating and drying apparatus in which the drying time of the cake is short and the drying unevenness does not occur is obtained by using the squeezed membrane having sufficient thermal conductivity for heating the sludge to be dehydrated and dried.

A preferred embodiment of the present invention is characterized in that a pressing membrane obtained by kneading 5 v / v% to 15 v / v% carbon graphite in a polyurethane resin is used as the pressing membrane.
In a preferred aspect of the present invention, the pressed film has a thermal conductivity of 0.35 W · m ⁻¹ · K ⁻¹ or more and 1.00 W · m ⁻¹ · K ⁻¹ or less.
A preferred embodiment of the present invention is characterized by comprising a vacuum generator for reducing the gap between the filter cloth and the compressed membrane.
In a preferred aspect of the present invention, the ultimate vacuum of the vacuum generator is 7 kPa or less.

A pair of squeezing membranes and a filter cloth are provided between a pair of adjacent filter plates, and a filter chamber composed of the squeezed membrane and the filter cloth is formed by tightening the filter plate with a clamping device, and sludge in the filter chamber is disposed on both sides. In the dewatering and drying apparatus for sludge to be squeezed, a passage of hot water is formed between the filter plate and the squeezed membrane, and the thermal conductivity is 0.35 W · m ⁻¹ · K ⁻¹ or more as the squeezed membrane. It is preferable to use a film having a high thermal conductivity of 0.000 W · m ⁻¹ · K ⁻¹ or less.

  Further, a mesh-like material having a thickness of 1 mm or more is disposed in the hot water passage between the filter plate and the compressed membrane, and the hot water is uniformly distributed over the entire surface of the hot water passage between the filter plate and the compressed membrane. It is preferable to do so. Moreover, it is preferable to circulate the warm water generated by the warm water generator in the warm water passage, and to arrange a back pressure valve and a bypass valve on the outlet side of the filter chamber of the circulation path of the warm water.

  As a result, the hot water is uniformly dispersed in the passage of the hot water facing the filter chamber between the filter plate and the compressed membrane. Then, when the sludge is heated and compressed, heat can be uniformly applied to the sludge to be pressed with a good efficiency by the pressing film having high thermal conductivity. Accordingly, the hot pressing drying of the sludge is promoted, and it becomes possible to make a cake having a required moisture content in a short time. Here, the hot water can be uniformly dispersed in the hot water passage by a network of 1 mm or more and 5 mm or less arranged in the hot water passage between the filter plate and the compressed membrane. Moreover, the pressure of warm water can be adjusted by arrange | positioning a back pressure valve and a bypass valve in the circulation path of warm water, and, thereby, the warming pressure of sludge and warming drying conditions can be adjusted quickly.

  Moreover, it is preferable that the groove | channel or processus | protrusion for filtrate discharge | emission whose groove depth or protrusion height is 3 mm or more and 10 mm or less is provided in the said pressing membrane between the said filter cloths. Furthermore, it is preferable that the vacuum generator is activated simultaneously with the squeezing with the hot water, and the sludge is heated, squeezed and dehydrated and dried under reduced pressure by setting the gap between the squeezing membrane and the filter cloth to a reduced pressure atmosphere.

  ADVANTAGE OF THE INVENTION According to this invention, the dehydration drying apparatus of the sludge which has the short drying time of a cake and does not produce a drying nonuniformity is obtained by using the pressing film | membrane which has sufficient thermal conductivity for the heating of the sludge of dehydration drying object.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows an outline of a sludge treatment system including a sludge dehydration drying apparatus of the present invention. The dehydration dryer 11 is a device that performs dehydration drying of sludge. By providing a pair of pressing membranes and a filter cloth between a pair of adjacent filter plates in the inside, and pressing the sludge in the filter chamber composed of the pressing membrane and the filter cloth from both sides by tightening the filter plate with a clamping device. This is a device for dewatering and drying sludge. Slurry (slurry) to be dehydrated and dried is supplied to the dehydrator 11 from the slurry supply line 13 through the supply valve 15 by the slurry supply pump 12. Then, the sludge is dehydrated and squeezed and dried by the dehydration dryer 11 to form a cake having a required moisture content, and is taken out from the dehydration dryer.

  The sludge dryer 11 is supplied with warm water, and this warm water promotes dewatering and drying of the sludge. Hot water is made by the hot water unit 31 and introduced into the header pipe 17 of the dehydrating dryer 11 from the hot water circulation line 35 by the hot water circulation pump 32. The hot water used for dewatering and drying sludge in the dehydration dryer 11 is returned from the header pipe 18 to the hot water unit 31 through the hot water circulation line 35. As described above, the hot water circulates between the hot water unit 31 and the dehydration dryer 11, and the back pressure valve 33 and the bypass valve 34 are arranged on the outlet side of the dehydration dryer 11. Therefore, by adjusting the back pressure valve 33 and switching to the bypass valve 34, it is possible to quickly adjust the flow rate of the circulating hot water and the pressure of the hot water in the dehydrating dryer.

  Further, vacuum suction is used for the dehydration drying of the sludge in the dehydration dryer 11. Therefore, the vacuum pump 37 and the condensing tank 38 are provided, and dehydration drying of the sludge inside the filter cloth is promoted by setting a reduced pressure atmosphere between the filter cloth and the compressed membrane. Moreover, the vacuum pump 37 is started simultaneously with the pressing step, and the gap between the pressing membrane and the filter cloth is depressurized so that the sludge in the filter cloth is heated, pressed and dehydrated and dried under reduced pressure.

  The center blow air is supplied to the dehydration dryer 11 through the center blow line 21 and is discharged from the center blow discharge mud line 23 together with the sludge that has not been dehydrated. An air valve 22 is connected to the center blow line 21, and a drainage valve 24 is connected to the center blow drainage line 23.

  The hot water unit 31 supplies hot water as a pressing medium and a warming medium, and keeps the temperature of the hot water at 70 ° C to 95 ° C. As the hot water unit 31, various heat sources such as a fuel such as electric power and oil, a hot water boiler using a combustion exhaust gas, a steam drain, a fuel cell waste water, or the like can be used. It is preferable that the hot water circulation pump 32 can apply a pressure of 0.5 MPa or more to the compressed film in the dehydration dryer 11. The filtrate line and the vacuum line connected to the dehydration dryer 11 are switched by the switching valves 1 and 2, and the condensation tank 38 and the vacuum pump 37 are connected to the vacuum line as described above. Cooling water circulates in the condensing tank 38. Here, the ultimate vacuum degree of the vacuum pump 37 is preferably 7 kPa or less.

  FIG. 2 shows a configuration example of a main part of a sludge dewatering dryer. As shown in the overall configuration example in FIG. 2C, a pair of squeezing membranes 52 and 52 and a filter cloth 51 and 51 are disposed between a pair of adjacent filter plates 54 and 54. Sludge to be dehydrated and dried is introduced into the filter cloths 51, 51, the plates 56, 57 are tightened from both sides by a tightening device (not shown), and the pair of filter plates 54, 54 are tightened from both sides. A filter chamber is formed in 51. As shown in FIGS. 2 (a) and 2 (b), a mesh-like object 53 having a thickness of 1 mm or more is disposed between the filter plate 54 and the compressed membrane 52, and between the filter plate 54 and the compressed membrane 52. A passage 53a through which warm water flows uniformly is secured.

  As the mesh-like material 53, a mesh made of a heat-resistant and corrosion-resistant material having a wire diameter of 0.5 mm or more can be used, and the material is preferably polyethylene, polypropylene, Teflon (registered trademark), stainless steel, or the like. . The thickness of the mesh 53 is preferably 1 mm or more, and if it is 5 mm or more, there is a problem that the volume of the filter chamber decreases.

Here, the pressing film 52 is a film having a high thermal conductivity of 0.35 W · m ⁻¹ · K ⁻¹ or higher. As such a squeezed membrane, a polyurethane resin kneaded with 5 v / v% to 15 v / v% carbon graphite can be used. Thereby, the heat of the hot water flowing through the hot water passage can be quickly supplied to the sludge in the filter chamber and the heat supply to the sludge in the filter chamber can be performed uniformly. However, 1.00 W · m ⁻¹ · K ⁻¹ or more has low strength and is not practical. Note that the thermal conductivity of a normal polypropylene resin is about 0.1 W · m ⁻¹ · k ⁻¹ , and that of a crosslinked polyethylene resin is about 0.38 W · m ⁻¹ · K ⁻¹ .

Moreover, a groove or protrusion 52a for discharging filtrate is provided on the filter cloth 51 side of the compressed membrane 52, and the depth of the groove or the height of the protrusion is preferably 3 mm or more and 10 mm or less, and a circle having a width of 2 to 6 mm. It is columnar or square, and in the case of a square, when the length becomes long, the concave portion becomes a groove. Here, if the depth of the groove or the height of the protrusion is 10 mm or more, the amount of heat conduction is reduced, and the same effect as when a resin having low heat conductivity is used is obtained.
Thereby, the vacuum suction path 52b in the gap between the compressed film 52 and the filter cloth 51 can be ensured uniformly. In addition, the material of a filter plate, a mesh-like material, and a filter cloth can be used as long as it is a material that can withstand a greenhouse at 70 ° C. to 95 ° C.

  Next, the outline of the dehydration drying process by this sludge dehydration drying apparatus will be described. As shown in FIG. 3, the basic sludge dehydration drying process includes a filtration process, a pressing process, a center blow, and a drying process.

  A filtration process is comprised from a non-warm filtration and a warm filtration, a pressing process is comprised from warm pressing, warm pressing, and reduced pressure drying, and a drying process is comprised from warm drying and reduced pressure drying. Optimal dehydration and drying can be performed by selecting components according to the properties of the sludge to be dehydrated and dried.

  Unheated filtration is a filtration process in which only the mud supply system is operated, and the introduced sludge is naturally filtered by the filter cloth 54. Warm filtration is a filtration process that operates a mud supply system and a hot water system. In this case, hot water is supplied to a hot water passage between the squeezed membrane 52 and the filter plate 54 by a hot water circulation line. In the dehydration dryer 11, a passage 53 a through which warm water flows uniformly is secured by the mesh-like material 53 installed between the filter plate 54 and the compressed membrane 52. And since the pressing film 52 is comprised with the material with high heat conductivity, and the warm water channel | path is ensured by the mesh-like object 53, this is efficient and non-uniform | heterogenous, and the heat of warm water is the filter cloth 51, It is transmitted to the sludge to be dried in 51.

  Warm pressing is a pressing process in which the sludge is heated while operating the hot water system. Moreover, reduced pressure drying is a pressing process which performs pressing in a reduced pressure atmosphere while operating a vacuum system. In these squeezing steps, it is preferable that the hot water circulates through the hot water circulation line 35 through the back pressure valve 33, and the hot water pressure in the vicinity of the filter chamber is gradually increased from a low pressure to a predetermined pressure by the back pressure valve 33. Thereby, favorable warming pressing can be performed.

  The drying step is a step of performing warming with warm water and drying under reduced pressure by operation of a vacuum device, and operates both the warm water system and the vacuum system. At this time, the hot water is preferably circulated through the bypass valve 34.

  As described above, the sludge dewatering and drying apparatus of the present invention uses a material having high thermal conductivity for the squeezed membrane, and a mesh-like material is disposed in the hot water passage so that the hot water flows uniformly in the passage near the filter chamber. It has become. And the back pressure valve is provided in the circulation path of warm water, and the pressure of warm water flowing to the back side of the squeezing membrane can be adjusted. Thereby, the heat which warm water has can be efficiently and uniformly transmitted to the sludge (cake) to be dehydrated and dried.

  Table 1 is for explaining the effects of the sludge dewatering and drying apparatus of the present invention, and shows the experimental results comparing the conventional dewatering and drying process and the dewatering and drying process of the present invention.

ろ過工程は無加温ろ過を採用し、圧搾工程は加温圧搾と減圧乾燥とを採用し、乾燥工程は加温しつつ減圧する乾燥工程に統一している。原料の汚泥濃度は２０ｇ／Ｌと、同条件の汚泥を使用している。ここで、圧搾膜の熱伝導率は、従来例１においては０．２３Ｗ・ｍ^−１・Ｋ^−１であるのに対して、本発明の例１及び例２では圧搾膜の熱伝導率が０．６８Ｗ・ｍ^−１・Ｋ^−１と高いものを用いている。また、圧搾工程における圧搾圧力は、従来例１及び本発明の例１では、０．５ＭＰａを採用し、本発明の例２では１．５ＭＰａを採用している。

The filtration process employs unheated filtration, the compression process employs warm pressing and drying under reduced pressure, and the drying process is unified with a drying process in which pressure is reduced while heating. The raw material sludge concentration is 20 g / L, and sludge of the same condition is used. Here, the thermal conductivity of the squeezed membrane is 0.23 W · m ⁻¹ · K ⁻¹ in Conventional Example 1, whereas in Examples 1 and 2 of the present invention, the thermal conductivity of the squeezed membrane is A high one of 0.68 W · m ⁻¹ · K ⁻¹ is used. Moreover, 0.5 MPa is employ | adopted in Example 2 of this invention, and 0.5 MPa is employ | adopted for the compression pressure in a pressing process in the prior art example 1 and the example 1 of this invention.

And as a result of experimenting by setting the final cake moisture content to 35%, the drying time in Conventional Example 1 is 2.17 h (hours), and the filtration rate is 0.25 kg · m ⁻² · h ^−1. On the other hand, in Example 1 of the present invention, the drying time was significantly shortened to 0.83 h (hours), and the filtration rate became 0.39 kg · m ⁻² · h ⁻¹ . In Example 2 of the present invention, as described above, the pressing pressure was 1.5 MPa, and as a result, the drying time was further reduced to 0.50 h (hours), and the filtration rate was 0.45 kg · m ⁻² · h ^−. It became ¹ .

From the above experimental results, it can be seen that the compressed film thermal conductivity greatly affects the length of the drying time. FIG. 4 shows the results of experiments performed under the same conditions as in Example 2 of the present invention by attaching compressed membranes having different thermal conductivities to this dehydrating and drying apparatus. The horizontal axis indicates the thermal conductivity of the pressed membrane, and the vertical axis indicates the filtration rate at which the cake moisture content is 35%. From this experimental result, it is shown that a high filtration rate can be obtained when the thermal conductivity is 0.35 W · m ⁻¹ · K ⁻¹ or more.

Table 2 shows the experimental results comparing the conventional pressure squeezing dehydration process (conventional example 2) and the dehydration drying process of the present invention (example 3).

In Conventional Example 2, both the filtration step and the pressing step were performed in an unheated state, and in Example 3 of the present invention, the filtration step was heated and the pressing step was performed by heating and pressing. As a raw material, the sludge of the same conditions with a density | concentration of 20 g / L is used. Moreover, in the prior art example 2, the temperature at the time of filtration and pressing was set to 20 ° C., and the moisture content of the cake was 60% at a pressing time of 0.80 h (hours), and the filtration rate was 0.46 kg · m ⁻² · h ⁻¹ . . On the other hand, in Example 3 of the present invention, as a result of setting the temperature during filtration and pressing to 80 ° C., a cake moisture content of 60% was obtained at a pressing time of 0.50 h (hours), and the filtration rate was 0.53 kg · m. ^-2 · h- ¹ . Also in the experimental results shown in Table 2, in the process using the dehydrating and drying apparatus of the present invention, the pressing time is greatly reduced, and the overall process time is reduced, thereby improving the filtration rate as a whole. I understand that.

  Moreover, when the cake after the dehydration drying process of the prior art example 1 and the prior art example 2 was observed, the difference was seen in the drying degree in the filter chamber periphery part and center part. On the other hand, in Examples 1 to 3 of the present invention, no difference was found in the degree of drying of the obtained cake. The difference in this effect is that a mesh-like material is arranged in the hot water passage between the filter plate and the squeezing membrane, thereby ensuring the uniformity of the hot water passage, and a groove or protrusion between the filter cloth and the squeezing membrane. This is considered to be due to the fact that the vacuum passage was secured thereby ensuring the uniformity of the decompression process.

  In addition, the said Example only described one form of the preferable Example of this invention, Of course, a various Example can be taken, without deviating from the meaning of this invention.

It is a block diagram which shows the dehydration drying apparatus of the sludge of embodiment of this invention. It is a figure which shows the principal part of the dehydration drying apparatus shown in FIG. 1, (a) is sectional drawing, FIG.2 (b) is a top view, FIG.2 (c) is sectional drawing which shows the whole structure. It is a flowchart which shows the dehydration drying process of sludge. It is a graph of the experimental result which shows the relationship between the heat conductivity of a pressing film, and the filtration rate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Dehydration dryer 12 Sludge supply pump 13 Sludge supply line 21 Center blow line 23 Center blow drainage line 31 Hot water unit 32 Hot water circulation pump 33 Back pressure valve 35 Hot water circulation line 37 Vacuum pump 38 Condensation tank 51 Filter cloth
52 Pressure Membrane 52a Projection or Groove 52b Vacuum Suction Channel 53 Network Item 53a Hot Water Channel 54 Filter Plate

Claims (5)

In a sludge dehydrating and drying apparatus for forming a filter chamber composed of a compression membrane and a filter cloth between filter plates, and pressing and drying the sludge in the filter chamber,
A hot water generator for generating hot water for heating the sludge in the filter chamber;
An apparatus for dewatering and drying sludge, wherein a compressed film obtained by kneading carbon graphite with polyurethane resin is used as the compressed film.   2. The sludge dewatering and drying apparatus according to claim 1, wherein a pressing film in which 5 v / v% to 15 v / v% carbon graphite is kneaded with polyurethane resin is used as the pressing film. The sludge according to claim 1 or 2, wherein a thermal conductivity of the pressed membrane is 0.35 W · m ^-1 · K ^-1 or more and 1.00 W · m ^-1 · K ^-1 or less. Dehydration drying equipment.   The sludge dewatering and drying apparatus according to any one of claims 1 to 3, further comprising a vacuum generator that depressurizes a gap between the filter cloth and the compressed membrane. 5. The sludge dewatering and drying apparatus according to claim 4, wherein the ultimate vacuum of the vacuum generator is 7 kPa or less.

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