JP2015116550A - Sludge dryer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sludge dryer that can suppress odors generated during drying of dewatered sludge, and can dry the dewatered sludge with smaller energy.SOLUTION: A sludge dryer 100, which dries dewatered sludge by fluidizing the dewatered sludge together with a fluid medium in a fluid bed 14 formed by fluidizing the fluid medium, comprises: a fluid drying part 10 that includes the fluid medium therein; a fluidizing gas introduction part 11 that introduces a fluidizing gas at 120 degrees or lower for introduction of the fluid medium to the fluid drying part 10; and a dried sludge carry-out port 12 that is disposed in an upper part of the fluid drying part 10 and carries out dried sludge dried by the fluid medium 14.

Description

  The present invention relates to a sludge drying apparatus, and more particularly to a sludge drying apparatus for drying dewatered sludge obtained by dewatering sludge.

  Sludge generated in sewage treatment plants, human waste treatment plants, wastewater treatment facilities, etc. must be dried for use in compost or subsequent heat treatment to reduce the moisture content of the sludge to a predetermined value or less. . Further, for use in compost or the like or subsequent heat treatment, it has been required that the obtained dried sludge has a suitable size.

  As a sludge drying apparatus for obtaining such dried sludge, a fluid bed drying type sludge drying apparatus capable of finely crushing while drying sludge with a fluidized bed formed by flowing a fluid medium (see, for example, Patent Document 1). ) Has been proposed. According to the sludge drying apparatus described in Patent Document 1, sludge can be dried and finely crushed while reducing equipment costs without using a crusher for crushing sludge into a desired size.

Japanese Patent Laid-Open No. 5-15900

Here, the sludge drying apparatus described in Patent Document 1 heats the fluid medium using steam at a high temperature (164 ° C.) and supplies heat for evaporating the moisture of the sludge by heat exchange with the steam. doing. For this reason, there existed a possibility that the odor component contained in sludge might melt | dissolve in vapor | steam moisture at the time of sludge drying, and an odor may be generated at the time of sludge drying. Furthermore, since the amount of heat for heating the fluidized medium and evaporating the water in the sludge is supplied as high-temperature (164 ° C.) water vapor as a heat source, the energy for preparing such a heat source is required when drying the sludge. This is necessary and the running cost of the sludge drying apparatus may increase.
Then, an object of this invention is to provide the sludge drying apparatus which can dry sludge with less energy while suppressing generation | occurrence | production of the odor at the time of drying sludge.

  The present inventors have intensively studied to achieve the above object. And the present inventors reduce the energy required when drying dehydrated sludge and the odor generated at the time of drying by drying dehydrated sludge by a combination of low-temperature dry air and fluidized bed type drying device. The present invention has been completed by newly discovering that it is possible.

  An object of the present invention is to advantageously solve the above-described problems, and is a sludge drying apparatus that causes dehydrated sludge to flow and dry together with the fluidized medium in a fluidized bed formed by fluidizing the fluidized medium. A fluidized drying part having the fluidized medium therein, a fluidizing gas introducing part for introducing a fluidizing gas of 120 degrees or less for fluidizing the fluidized medium into the fluidized drying part, and the fluidized drying. And a dried sludge outlet for discharging dried sludge dried by the fluidized bed. In this way, a fluidized bed is formed by flowing a fluid medium with a low-temperature fluidizing gas, and the dehydrated sludge is dried in the fluidized bed, thereby generating energy necessary for drying the dehydrated sludge and drying. Odor can be significantly reduced.

  Here, in the sludge drying apparatus of the present invention, the fluidized drying unit has a light transmitting part that transmits light and is disposed above the region where the fluidized bed is formed in the vertical direction of the fluidized drying unit. It is preferable that By providing the light transmission part in the fluid drying part, the dehydrated sludge can be dried more efficiently by the energy of light (for example, sunlight) that has reached the fluid drying part through the light transmission part. is there.

  Moreover, in the sludge drying apparatus of the present invention, the fluid drying section has a unidirectional inclination at the bottom, and the fluid gas introduction section supplies the fluid gas supplied into the fluid drying section. It is preferable to have a distribution forming mechanism that forms a distribution in the supply speed. It is because a gradient can be formed in the abundance of the fluid medium in the fluidized drying unit because the bottom of the fluidized drying unit has an inclination in one direction. Then, by forming a distribution in the supply amount and supply speed of the flow gas, the dehydrated sludge having a relatively high water content is flowed in the region where the amount of the fluid medium is large, and in the region where the amount of the fluid medium is small. This is because dehydrated sludge having a relatively low drying rate and low water content can be made to flow.

  Further, in the sludge drying apparatus of the present invention, the fluidized drying unit is arranged above the region where the fluidized bed is formed in the vertical direction of the fluidized drying unit, and the ascending air current assisting the removal of the dried sludge. It is preferable to have an unloading air supply part for supplying unloading air for forming the air. This is because the drying drying sludge can be efficiently carried out by providing the air drying section with the fluid drying section.

  Furthermore, in the sludge drying apparatus of the present invention, the carry-out air supply unit has at least a pair of carry-out air supply ports, and the at least a pair of carry-out air supply ports are in the direction facing each other. It is preferable that it arrange | positions so that may be ejected. By having at least a pair of unloading air supply ports arranged so that the unloading air supply unit jets the unloading air in a direction facing each other, an ascending air current is formed in the fluidized drying unit, and the dry sludge This is because the carrying out can be made more efficient.

  According to the sludge drying apparatus of the present invention, it is possible to suppress the generation of odor when drying the sludge and dry the sludge with less energy.

It is a figure which shows schematic structure of the typical sludge drying apparatus according to this invention. It is a figure which shows the 1st modification of the sludge drying apparatus according to this invention. It is a figure which shows the 2nd modification of the sludge drying apparatus according to this invention. It is a figure which shows the 3rd modification of the sludge drying apparatus according to this invention.

  Hereinafter, the sludge drying apparatus of this invention is demonstrated in detail based on drawing.

<Sludge drying equipment>
A sludge drying apparatus 100 shown in FIG. 1 includes a fluidized drying unit 10, a fluidizing gas introducing unit 11, and a dried sludge carrying-out port 12. The sludge drying apparatus 100 flows the dehydrated sludge supplied into the fluidized drying unit 10 through the dehydrated sludge supply pipe 13 together with the fluidized medium in the fluidized bed 14 formed by fluidizing the fluidized medium in the fluidized drying unit 10. Let dry.

  The fluid drying unit 10 has a fluid medium inside, and the fluid medium is, for example, silica sand (sandstone). The fluid medium is supplied by the fluid gas supplied from the fluid gas inlet 11 </ b> A of the fluid gas introduction unit 11 that introduces a fluid gas of 120 degrees or less for fluidizing the fluid medium to the fluid drying unit 10. It is fluidized to form a fluidized bed 14. In the fluidized bed 14, the fluid medium flows together with the dehydrated sludge supplied into the fluidized drying unit 10 via the dehydrated sludge supply pipe 13, and the dehydrated sludge is dried while being finely crushed. When the fluidized medium finely crushes the dewatered sludge, the surface area of the dehydrated sludge increases and it becomes easy to dry. In addition, by using the fluidized bed 14, the volume of the fluidized drying unit 10 can be reduced as compared with the conventional stirring type stirring mechanism.

  The dewatered sludge supplied through the dewatered sludge supply pipe 13 is preferably a two-component dewatered sludge. Two-component dewatered sludge is, for example, dehydrated sludge obtained by using an organic flocculant and an iron-based inorganic flocculant (polyferric sulfate) in combination. Two-component dewatered sludge has a lower moisture content than dehydrated sludge (one-component dehydrated sludge) obtained by dehydration treatment using only organic coagulants such as organic polymer coagulants that have been used in the past. The drying efficiency by the apparatus 100 can be improved. Furthermore, the two-component dewatered sludge is preferably granular. This is because if the two-component dewatered sludge is granular, it has a large surface area that contributes to drying, and can be dried with a relatively low temperature fluidizing gas. The granular two-component dewatered sludge can be obtained, for example, by dehydration using a centrifugal dehydrator. Furthermore, the two-component dewatered sludge obtained using polyferric sulfate has a low odor.

The temperature of the fluidizing gas is usually more than 0 degree, preferably 10 degrees or more, particularly preferably 20 degrees or more, usually 120 degrees or less, preferably 100 degrees or less, more preferably 80 degrees or less, particularly preferably 50 degrees or less. It is. By making the temperature of the gas for flow more than 0 degree, it is possible to avoid freezing of moisture present in the fluidized drying unit 10 and to ensure the minimum drying efficiency. Furthermore, by setting the temperature of the flowing gas to 120 ° C. or less, it is possible to suppress the generation of odor when drying the dewatered sludge and to dry the dehydrated sludge with less energy than in the past. In particular, by setting the temperature of the gas for flow to 20 degrees or more and 50 degrees or less, it is possible to achieve both high efficiency in drying efficiency of dehydrated sludge and suppression of odor generation when drying the dehydrated sludge. Furthermore, sunlight heat, geothermal heat, sewage heat, and the like can be used as a heat source for warming the flowing gas to a temperature range of more than 0 degrees and 120 degrees or less. These heat sources are preferable in terms of economy and environmental load in that they do not require any additional fuel energy.
Moreover, it is preferable that the flowing gas is dehumidified by a dehumidifier (not shown) attached to the flowing gas introduction unit 11. This is because the drying efficiency of the dewatered sludge can be further improved.

  Here, the flow rate of the fluidized bed 14 is controlled by the supply amount of the fluidizing gas introduced through the fluidizing gas introduction unit 11, but depending on the total amount of the fluidized medium and the size of the fluidized drying unit 10, A suitable value of the supply amount of the working gas can be obtained. The flowing gas introducing unit 11 of the sludge drying apparatus 100 according to the present embodiment supplies the flowing gas into the fluidized drying unit 10 at a suitable supply amount and supply speed thus determined.

  The dewatered sludge supplied into the fluid drying unit 10 via the dewatered sludge supply pipe 13 gradually becomes particles after being crushed and dried in the fluidized bed 14 from a relatively high moisture content. However, the water content becomes low and the fluid is pushed up to the upper part of the fluidized bed 14 and easily floats. Then, the sludge having a low water content in which the floating flow rate, which is the minimum flow rate required to float the sludge, is lower than the flow rate of the flowing air flows in the vertical direction of the fluidized drying unit 10 by the flowing air. It is conveyed upward from the region where the layer 14 is formed. Hereinafter, sludge having a floating flow rate lower than the flow rate of flowing air is also referred to as dry sludge.

  Here, it is preferable that the upper part of the fluidized drying unit 10 is tapered, and the dried sludge carry-out port 12 from which the transported dried sludge is carried out is the upper part of the fluidized drying unit 10 having a tapered shape. It is preferably located at the top. The dried sludge that has been transported from the fluidized bed 14 by the fluidizing gas and reached the top of the fluidized drying unit 10 has a low water content and a small particle size, and therefore has a low floating flow rate. Here, the upper part of the fluid drying unit 10 is tapered so that the flow path of the dried sludge is gradually narrowed, and the resistance in the flow path is reduced, thereby gradually increasing the floating flow rate and efficiently transporting the dried sludge. can do. Furthermore, since the diameter of the dried sludge transport pipe 31 is smaller than that of the fluidized drying unit 10, the flow rate is high. Thus, since the sludge drying apparatus 100 can carry out dry sludge efficiently from the fluid drying part 10 with air, conveyance power, such as a conveyor, is unnecessary.

  In addition, the upper part of the fluidized-drying part 10 here is above the area | region in which the fluidized bed 14 is formed in the perpendicular direction of the fluidized-drying part 10, for example. It is an area within 3. Further, in the present specification, the “tapered shape” is not limited to the shape as shown in FIG. 1, and refers to any shape that is tapered, for example, a linear tapered shape, an exponential tapered shape, a parabolic tapered shape, or the like. Including shapes that can be expressed by the function of, and shapes that do not depend on the function.

In the subsequent stage of the sludge drying device 100, for example, a solid-gas separation device 40 is provided, and the dried sludge and the transported gas conveyed from the sludge drying device 100 through the dried sludge transport pipe 31 are separated. The solid-gas separation device 40 is constituted by, for example, a cyclone. The separated dried sludge is recovered via the sludge discharge pipe 33 and can be converted into fuel and composted through, for example, incineration, gasification, disposal, packing and carbonization. Further, the separated carrier gas is conveyed through the carrier gas exhaust pipe 32 and can be used as combustion air for an incinerator or melting furnace, or can be released into the atmosphere after being deodorized.
Alternatively, for example, the dried sludge carried out together with the air from the sludge drying device 100 can be directly used as the burner fuel without going through the solid-gas separation device 40 or the like.
Hereinafter, the structure which can be mentioned as a modification of the sludge drying apparatus 100 is explained in full detail.

(First modification)
FIG. 2 is a view showing a first modification of the sludge drying apparatus according to the present invention. About each structural part similar to each structural part of the sludge drying apparatus 100 shown in FIG. 1, the value which added 100 to the same referential mark is attached | subjected. The shape of the upper part of the fluid drying unit 110 shown in FIG. 2 may of course be the same shape as in FIG. In the sludge drying apparatus 200 according to the first modification, the fluid drying unit 110 is disposed above the region where the fluidized bed 114 is formed in the vertical direction of the fluid drying unit 110 and transmits light. Part 116. By providing the light transmission part 116 in the fluid drying part 110, the dewatered sludge can be dried more efficiently by the energy of light (sunlight) that has reached the fluid drying part 110 via the light transmission part 116. it can.

  The light transmitting portion 116 is made of a material such as glass, quartz, and acrylic resin. In particular, in the present invention, since the temperature of the flow air is as low as 120 ° C. or less, even if a material having a relatively low melting point such as an acrylic resin (melting point 160 ° C.) is used for the light transmitting portion 116, it is not dissolved. The fluid drying unit 110 can be formed without causing a problem. Moreover, it is preferable that the inner side of the light transmission part 116 is subjected to wear resistance processing. For example, by arranging a metal mesh, a punching metal, or the like inside the light transmitting portion 116 to provide wear resistance while transmitting light, for example, wear resistance against contact with a fluid medium such as dredged sand or sludge. Can be improved.

  Further, the fluidized drying unit 110 according to this modification includes a fluidized bed forming unit 115. The fluidized bed forming unit 115 extends from the bottom to a height of about 1/3 to about 1/2 of the whole in the vertical direction of the fluidized drying unit 110. The fluidized bed forming part 115 can be made of a material having high wear resistance against contact with a fluid medium such as steel. The fluidized bed forming unit 115 is connected to the light transmitting unit 116 by a general method. For this connection, for example, a flange portion is formed in each of the fluidized bed forming portion 115 and the light transmitting portion 116, and a packing or an O-ring is interposed between both flanges, and these are fixed by bolts. Can do.

  As described above, the sludge drying apparatus 200 according to this modification uses the thermal energy of light (sunlight) that has reached the fluid drying unit 110 via the light transmission unit 116, and the temperature in the fluid drying unit 110. To raise. Therefore, in order to collect thermal energy more efficiently, it is preferable to provide a heat absorption promoting member in the fluidized drying unit 110. Examples of the endothermic promotion member include black inorganic compounds such as metal oxide compounds that can flow together with the fluid medium. The black inorganic compound can be used in addition to the fluid medium or in place of the fluid medium. It is also beneficial to make the inside of the fluidized bed forming portion 115 black for efficient heat energy collection.

  Furthermore, when sunlight is used as a heat energy source, there is no supply of heat energy at night, but when sand is used as a fluid medium, a heat storage effect is generated due to the heat retaining property of the sand itself, and the fluid drying unit 110 The temperature drop can be alleviated. In addition, in order to further alleviate the temperature drop in the fluid drying unit 110, it is further preferable that the sludge drying apparatus 200 according to this modification includes a heat storage member.

(Second modification)
FIG. 3 is a view showing a second modification of the sludge drying apparatus according to the present invention. About each component similar to each component of the sludge drying apparatus 100 shown in FIG. 1, the value which added 200 to the same referential mark is attached | subjected. In FIG. 3, the fluid drying unit 210 has a unidirectional inclination at the bottom, and the fluid gas introduction unit 211 has a distribution in the supply amount and the supply speed of the fluid gas supplied into the fluid drying unit 210. It has distribution forming mechanisms 217A to 217D to be formed. Due to the unidirectional inclination provided at the bottom of the fluid drying section 210, the fluid medium can be distributed in an inclined manner. In addition, the structure which concerns on this modification can be used in combination with the structure concerning a 1st modification.

  Each of the distribution forming mechanisms 217A to 217D is a pipe that supplies a flow gas into the flow drying unit 210, and each has a plurality of flow gas introduction ports. The distribution forming mechanism 217A has the largest supply amount and supply speed of the flow gas, the distribution forming mechanism 217D has the smallest, and the distribution forming mechanisms 217B and C have a supply amount and a supply speed therebetween. An arrow 219 schematically shows a flowing gas ejected from the distribution forming mechanism 217A. Similarly, arrows are shown for the distribution formation mechanisms 217B to 217D, and the flow gas ejected from the distribution formation mechanisms B to D is also schematically shown. In order to set the velocity of the flow gas supplied by each distribution formation mechanism 217A to 217D to a value unique to each distribution formation mechanism 217A to 217D, for example, the size of the flow gas inlet of the distribution formation mechanism 217A And increasing the size of the flow gas inlet of the distribution forming mechanism 217D. Further, as an implementation example for adjusting the supply amount for each of the distribution forming mechanisms 217A to 217D, using an air volume adjusting damper disposed on a line (not shown) for introducing a flow gas into the distribution forming mechanisms 217A to 217D, and For example, the flow rate of the flow gas may be varied by giving a pressure loss by varying the number of flow gas introduction ports in each of the distribution forming mechanisms 217A to 217D.

  Then, the distribution formation mechanisms 217A to 217D increase the supply amount and supply speed of the flow gas so as to increase in a region where the abundance of the fluid medium is large and decrease in a region where the abundance of the fluid medium is small. Thus, the fluid medium can be caused to flow in each region. According to the fluidized bed 214 having the gradient distribution of the abundance of the fluidized medium formed in this way, the dehydrated sludge 218A having a relatively high water content moves to a region with a large amount of the fluidized medium according to gravity, It is considered that the light dewatered sludge 218B having a low water content moves along the fluidized sand layer surface (the surface of the fluidized bed 214) to a region where there is little fluid medium. In this way, the density of the fluid medium relative to the dewatered sludge can be changed in accordance with the degree of drying of the dewatered sludge, so that the drying of the dewatered sludge can be made more efficient.

  The shape of the fluid drying unit 210 is preferably a quadrangular prism. In particular, it is preferably a quadrangular prism whose bottom surface is a rectangle having a long side in the tilt direction and a short side in the direction orthogonal to the tilt direction. This is because the gradient distribution of the fluid medium can be formed over the length in the long side direction, so that the moving bed can be formed at a relatively long distance, and the drying efficiency can be further improved.

(Third Modification)
FIG. 4 is a view showing a third modification of the sludge drying apparatus according to the present invention. About each structural part similar to each structural part of the sludge drying apparatus 100 shown in FIG. 1, the value which added 300 to the same referential mark is attached | subjected. In FIG. 4, the fluid drying unit 310 is a carry-out for forming a rising air flow that is arranged above the region where the fluidized bed 314 is formed in the vertical direction of the fluid dry unit 310 and assists carrying out the dried sludge. It has unloading air supply parts 320A and 320B for supplying working air. The carry-out air supply units 320A and 320B are arranged such that the carry-out air supply ports are directed obliquely upward and face each other. The carry-out air supplied via the carry-out air supply units 320 </ b> A and 320 </ b> B collides with each other in the fluid drying unit 310 to form an ascending current. This rising air flow can assist in transporting the dried sludge whose moisture content is below a predetermined value. In addition, the structure which concerns on this modification can be used in combination with the structure which concerns on a 1st modification and / or a 2nd modification.

  It has been found that when sludges with various moisture contents are the same and the flow rate of the fluidized bed is constant, the sludge with a lower moisture content has a lower weight (density) and therefore has a higher floating height. Moreover, in facilities such as a sewage treatment plant where the sludge drying apparatus according to the present invention can be introduced, a target moisture content of the dried sludge is determined for each facility. Therefore, by arranging the air supply units 320A and 320B for carrying out so as to form the above-mentioned rising airflow at the floating height of the dry sludge having a target moisture content, the dry sludge having a desired moisture content can be efficiently obtained. It can be carried out from the fluid drying unit 310. Furthermore, by adjusting the supply amount of the discharge air according to the arrangement position of the discharge air supply units 320A and 320B, a flow rate necessary and sufficient for the discharge is provided to the dry sludge having a desired moisture content. In addition, the drying sludge can be carried out more efficiently. The flow rate necessary and sufficient for carrying out the drying sludge having a desired water content can be determined, for example, based on the terminal velocity calculated for the drying sludge having a desired water content to be carried out.

  According to the sludge drying apparatus 400 according to the present modification, the conditions of the fluidized bed such as the supply amount and supply speed of the fluidizing gas are constant, and the unloading air supplied via the unloading air supply units 320A and 320B The dried sludge having a predetermined moisture content or less can be carried out from the fluidized drying unit 310. Therefore, both maintaining the conditions of the fluidized bed in the most suitable state and obtaining dry sludge having a desired water content can be achieved.

  4 shows two carry-out air supply units 320A and 320B, the sludge drying apparatus 400 further includes two or more carry-out air supply units at the same height in the vertical direction of the fluid drying unit 310. You may have. Since the sludge drying apparatus 400 has four or more carry-out air supply units, dry sludge having a desired moisture content can be carried out from the fluidized drying unit 310 more efficiently.

  Furthermore, the sludge drying apparatus 400 may have a pair or a plurality of pairs of air supply units for unloading at a plurality of heights in the vertical direction of the fluid drying unit 310. In the operation of the sludge drying apparatus 400, the moisture content of the obtained dried sludge can be selected by switching and using these carry-out air supply units for each height.

  As mentioned above, although the sludge drying apparatus of this invention was demonstrated using some examples, the sludge drying apparatus of this invention is not limited to the said example, A change can be added suitably.

  According to the sludge drying apparatus of the present invention, it is possible to suppress the generation of odor when drying the sludge and dry the sludge with less energy.

10, 110, 210, 310: Fluidized drying sections 11, 111, 211, 311: Flowing gas inlets 11A, 111A, 211A, 311A: Fluidized gas inlets 12, 112, 212, 312: Dried sludge carry-out port 13 113, 213, 313: dehydrated sludge supply pipes 14, 114, 214, 314: fluidized beds 31, 131, 231, 331: dry sludge transport pipes 100, 200, 300, 400: sludge drying apparatus 32: transport gas exhaust pipe 33: Sludge discharge pipe 40: Solid-gas separation device 115: Fluidized bed formation unit 116: Light transmission unit 217A to D: Distribution formation mechanism 320A, B: Unloading air supply unit

Claims (5)

A sludge drying device for flowing and drying dehydrated sludge together with the fluidized medium in a fluidized bed formed by fluidizing the fluidized medium,
A fluid drying section having the fluid medium therein;
A flow gas introduction section for introducing a flow gas of 120 degrees or less for flowing the fluid medium with respect to the fluid drying section;
A dried sludge outlet for discharging the dried sludge dried at the top of the fluidized drying unit and dried by the fluidized bed;
A sludge drying device.   2. The sludge according to claim 1, wherein the fluid drying unit includes a light transmission unit that transmits light and is disposed above a region where the fluidized bed is formed in a vertical direction of the fluid drying unit. Drying equipment. The fluidized drying section has a unidirectional inclination at the bottom,
The flow gas introduction unit has a distribution forming mechanism that forms a distribution in the supply amount and supply speed of the flow gas supplied into the fluid drying unit.
The sludge drying apparatus according to claim 1 or 2. The fluidized-drying unit supplies unloading air for forming an updraft that is disposed above the region where the fluidized bed is formed in the vertical direction of the fluidized-drying unit and assists the unloading of the dried sludge. Having an air supply unit for carrying out,
The sludge drying apparatus as described in any one of Claims 1-3. The unloading air supply unit has at least a pair of unloading air supply ports, and the at least a pair of unloading air supply ports are arranged to eject the unloading air in directions facing each other.
The sludge drying apparatus according to claim 4.

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