JP2023101485A - Heat recovery device from sludge, heat recovery system from sludge, and factory utilizing heat recovered from sludge - Google Patents

Abstract

To provide a heat recovery device and a heat recovery system from sludge in a form of electric heat energy without using a special device of converting sludge to fuel, capable of reducing the cost of transporting dried sludge, and suppressing odor and dust when transporting dried sludge.SOLUTION: The heat recovery device from sludge, at least comprises a conveyer and a solid fuel boiler in this order, with the conveyer at least conveying dried sludge to the solid fuel boiler. The moisture content in the dried sludge preferably is 5 to 40 mass%. The conveyer preferably conveys RPF containing at least one species selected from plastic, paper and paper sludge, or coal, and dried sludge to the solid fuel boiler.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a sludge heat recovery device, a sludge heat recovery system, and a sludge heat utilization type factory.

Various devices and methods are known as devices and methods for processing sludge into fuel for boilers (see Patent Documents 1 to 6).

Patent Document 1 describes a fuel manufacturing method using organic sludge, which includes a dehydration step of dehydrating the organic sludge to obtain dewatered sludge, and a mixing step of mixing the dewatered sludge with at least one of wood chips and sawdust to obtain mixed wood sludge.
Furthermore, Patent Document 1 describes a sludge reuse system that uses the produced fuel, in which organic sludge is dehydrated at a sludge treatment plant, the dehydrated sludge is transported to a fuel production facility by a vehicle, the dehydrated sludge is mixed with at least one of wood chips and sawdust to produce fuel, the fuel is transported to a combustion facility by a vehicle, and the fuel is burned in the combustion facility.

Patent Document 2 includes a dephosphorization step of removing phosphorus contained in sewage sludge and a carbonization step of carbonizing the sewage sludge and converting it into fuel. Also, a method for producing biomass fuel is described in which an adsorbent containing hydroxyapatite crystals as a main component is obtained by reacting phosphoric acid and gypsum in an alkaline solution while maintaining the pH at the end of the reaction at 12 or higher.

Patent Document 3 describes a solid fuel production method in which organic waste such as sewage sludge, paper sludge, and food sludge is dried to a moisture content of 20 to 60%, granulated, carbonized at a carbonization temperature of 300 to 600 ° C. for 4 to 22 minutes using a rotary kiln in an air-blocked atmosphere, and then immediately cooled, and the carbonized product after cooling is dried at a drying temperature of 70 ° C. or higher and 150 ° C. or lower for a drying time of 2 to 7 hours.

Patent Document 4 describes an organic sludge-derived solid fuel obtained by drying organic sludge and then carbonizing it, wherein the atomic ratio H/C between the hydrogen content and the carbon content is 0.8 to 1.8, and is a solid fuel that burns with coal. Organic sludge-derived solid fuel is described.

In Patent Document 5, the organic waste is anaerobic digestion sludge or sludge generated in a sewage treatment plant, and the RPF (Refuse Paper & Plastic Fuel) manufacturing raw material contains a total of 50% by mass or more of plastic and/or paper. A method for producing a solid fuel is described, which includes a mixing step of adjusting the mixing ratio of organic waste and RPF production raw materials so as to satisfy the following formula (I) to obtain a mixed raw material containing them, and a molding step of obtaining a molded body from the mixed raw material.
Formula (I): y≦−0.0436x ² +1.7458x+40.0

In Patent Document 6, sewage sludge, night soil sludge, food waste, livestock waste, or digested sludge thereof are subjected to a drying treatment to adjust the moisture content to 20 to 50% by mass. Organic waste is held in an atmosphere at a temperature of 20 to 65° C. for 12 to 120 hours to obtain a matured waste, and a mixing step to obtain a mixed raw material containing RPF manufacturing raw materials containing a total of 50% by mass or more of the aged waste and plastic and/or paper. , and a molding step of obtaining a molding from a mixed raw material.

JP 2015-25054 A Patent No. 5001594 Patent No. 4368964 Japanese Patent Application Laid-Open No. 2007-119641 Patent No. 6022259 Patent No. 6047337

However, the methods described in Patent Documents 1 and 2 have a problem that the transportation cost is high because the fuel produced from the dried sludge is transported to the combustion facility by a vehicle, and odor and dust are generated when the fuel produced from the dried sludge is transported.
The methods described in Patent Documents 3 and 4 are to produce a solid fuel by granulating organic waste such as sewage sludge and then carbonizing it using a rotary kiln or the like, and reducing the transportation cost when transporting the obtained solid fuel to a combustion facility has not been considered.
The methods described in Patent Documents 5 and 6 are for manufacturing solid fuel by mixing organic waste such as sewage sludge with RPF manufacturing raw materials and molding them, and no consideration has been given to reducing the transport cost when transporting the obtained solid fuel to a combustion facility.

The problem to be solved by the present invention is to provide a device and system that can reduce the cost of transporting dried sludge, suppress odor and dust when transporting dried sludge, and recover the heat of sludge into electric heat energy without using a special sludge fuel conversion device.
Another problem to be solved by the present invention is to provide a sludge heat recovery system and a sludge heat utilization type factory including the above sludge heat recovery device.

The configuration of the present invention, which is a specific means for solving the above problems, and the preferred configuration of the present invention will be described below.

[1] Equipped with at least a conveying unit and a solid fuel boiler in this order,
A sludge heat recovery device, wherein the conveying section conveys at least dried sludge to a solid fuel boiler.
[2] The sludge heat recovery apparatus according to [1], wherein the dry sludge has a moisture content of 5 to 40% by mass. [3] The sludge heat recovery apparatus according to [1] or [2], wherein the conveying section conveys RPF or coal containing at least one of plastic, paper and paper sludge, and dry sludge to the solid fuel boiler.
[4] The sludge heat recovery apparatus according to any one of [1] to [3], further comprising a sludge drying section, wherein the sludge drying section obtains dried sludge.
[5] The sludge heat recovery device according to any one of [1] to [4], wherein the conveying section has dry sludge crushing means or further comprises a sludge drying section, and the sludge drying section has dry sludge crushing means.
[6] When the total net calorific value of all fuels supplied to the solid fuel boiler is ^Q1 and the net calorific value of the dried sludge is ^Q2 , the dried sludge satisfies the following conditions 1A, 1B, or 1C. The sludge heat recovery apparatus according to any one of [1] to [5].
Condition 1A: The moisture content of dried sludge is 20% by mass or less, and the value of 100%×Q ² /Q ¹ is 40% or less.
Condition 1B: The moisture content of the dried sludge is more than 20% by mass and 30% by mass or less, and the value of 100%×Q ² /Q ¹ is 20% or less.
Condition 1C: The moisture content of the dried sludge is more than 30% by mass and 40% by mass or less, and the value of 100%×Q ² /Q ¹ is 10% or less.
[7] The sludge heat recovery apparatus according to any one of [1] to [6], wherein the conveying unit conveys the dried sludge together with the coal to the solid fuel boiler by airflow conveyance.
[8] the solid fuel boiler further comprising an input for additional fuel;
The sludge heat recovery device according to any one of [1] to [7], wherein the additional fuel includes at least one of coal, plastic, paper, wood chips and rubber.
[9] the solid fuel boiler further comprising a generator;
The sludge heat recovery device according to any one of [1] to [8], wherein the power obtained from the generator is supplied to the conveying section, or the sludge heat recovery device further includes a sludge drying section and supplies the power to the sludge drying section.
[10] The sludge heat recovery apparatus according to any one of [1] to [9], wherein the means for transporting the dried sludge transported to the transport part is a vehicle, or the sludge heat recovery apparatus further comprises a sludge drying part, and the means for transporting the sludge transported to the sludge drying part is a vehicle.
[11] A sludge heat recovery device and a sewage treatment plant according to any one of [1] to [10],
A sludge heat recovery system in which dry sludge made of sludge obtained at a sewage treatment plant is conveyed to a conveying section by a vehicle, or the sludge heat recovery device further includes a sludge drying section, and sludge obtained at a sewage treatment plant is conveyed to the sludge drying section by a vehicle.
[12] The sludge heat recovery device according to any one of [1] to [10] or the sludge heat recovery system according to [10];
Equipped with factory and
Equipped with piping to supply the factory with steam obtained from the solid fuel boiler,
Sludge heat utilization type factory where the factory is a paper mill.
[13] the solid fuel boiler further comprises a generator;
The sludge heat utilization type factory according to [12], which supplies power obtained from the generator to the factory.

According to the present invention, a sludge heat recovery device, a sludge heat recovery system, and a sludge heat utilization type factory can be provided without installing a new heat recovery device or heat recovery system.

FIG. 1 is a schematic diagram showing an example of a sludge heat recovery system and a sludge heat utilization type plant of the present invention, which is equipped with a sludge heat recovery apparatus of a preferred embodiment of the present invention.

The present invention will be described in detail below. Although the constituent elements described below may be described based on representative embodiments and specific examples, the present invention is not limited to such embodiments. In the present specification, a numerical range represented by "-" means a range including the numerical values described before and after "-" as lower and upper limits.

[Sludge heat recovery device]
The sludge heat recovery apparatus of the present invention comprises at least a conveying section and a solid fuel boiler in this order, and the conveying section conveys at least dry sludge to the solid fuel boiler.
According to the present invention, a sludge heat recovery device and a sludge heat utilization type factory can be provided without installing a new heat recovery device or heat recovery system. In addition, the transportation cost of dried sludge can be reduced, and odor and dust can be suppressed when the dried sludge is conveyed.

For example, after drying sewage sludge etc. in the sludge drying department (so-called drying business, including carbonization) to make dried sludge, by conveying the obtained dried sludge in a short time, odor and dust can be suppressed, and it can be used as a solid fuel for boiler input without being treated as industrial waste. For convenience in the present invention, the fuel containing dried sludge and others conveyed to the solid fuel boiler is sometimes referred to as solid fuel derived from dried sludge, or simply solid fuel.
Specifically, the transport cost can be greatly reduced by transporting the dried sludge to the solid fuel boiler via the integrated transport unit in the sludge heat recovery device. In addition, odor during transportation can be suppressed.

In a preferred embodiment of the sludge heat recovery apparatus of the present invention, the solid fuel derived from dried sludge is conveyed as it is to the solid fuel boiler, and the obtained steam and electric power (when the solid fuel boiler is equipped with a generator) are used in the sludge heat recovery apparatus and the sludge fuel utilization type factory of the present invention. Therefore, the dried sludge can be used more effectively. In addition, with conventional methods and devices that use dried sludge as solid fuel, the number of businesses with large-scale solid fuel boilers (biomass boilers, coal boilers, etc.) was limited, so the supply of solid fuel derived from dried sludge obtained sometimes exceeded demand. Since the preferred embodiment of the sludge heat recovery apparatus of the present invention does not produce excessive dry sludge-derived solid fuel, it is not necessary to dispose of such excessive dry sludge-derived solid fuel as industrial waste at a cost, and the cost at the time of disposal can be reduced. In addition, the amount of landfill disposal of waste can be reduced.
Furthermore, by using the sludge heat recovery apparatus of the present invention, the solid fuel boiler can be operated as a solid fuel (certified as a valuable resource) by granulating the dried sludge, etc. Therefore, the dry sludge is not disposed of as industrial waste, the solid fuel boiler can be operated efficiently, and CO ₂ emissions can be reduced. In recent years, businesses are sometimes required to submit their own efforts for global warming countermeasures and _CO2 emission reduction targets to public organizations as a "manifest" (action declaration).
Preferred embodiments of the sludge heat recovery apparatus of the present invention are described below.

<Configuration of sludge heat recovery device>
The overall configuration of the sludge heat recovery device will be described.
In the present invention, the sludge heat recovery device includes at least the conveying section and the solid fuel boiler in this order.
A preferred embodiment of the sludge heat recovery device will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an example of a sludge heat recovery system and a sludge heat utilization type plant of the present invention, which is provided with a sludge heat recovery device (preferred embodiment) of the present invention.
In FIG. 1, the sludge heat recovery device 101 is provided with a sludge drying section 11, a conveying section 41 and a solid fuel boiler 51 provided as necessary in this order.
Dried sludge is obtained in a sludge drying section 11 provided as necessary.
The conveying unit 41 conveys at least the dried sludge 22 to the solid fuel boiler 51 .
Each configuration of the sludge heat recovery apparatus of the present invention will be described in order.

<Sludge drying section>
The sludge drying section may be provided at least by, for example, a sewage treatment plant or a drying business operator. In the present invention, it is preferable that the sludge heat recovery device further includes a sludge drying section, and dry sludge is obtained in the sludge drying section. The sludge supplied to the sludge drying section is not particularly limited. Examples thereof include various organic sludges such as sewage sludge, paper sludge, building pit sludge, and food sludge. Among these, it is particularly preferable to use sewage sludge.
The sludge supplied to the sludge drying section is preferably dehydrated sludge that has been dewatered to some extent. More preferably, the sludge drying unit 11 dries the sludge 3 dehydrated to some extent by the sludge dehydrator 2 of the sewage treatment plant 1 to obtain the dried sludge 12 .
The moisture content of dewatered sludge is usually 70-85% by mass. The dewatered sludge is sometimes referred to as a dewatered cake, and may be solid or fluid. When the dehydrated sludge has fluidity, the degree of fluidity is not particularly limited as long as it can be sucked up by a suction vehicle, a so-called vacuum vehicle. It is preferable that the means for transporting dried sludge transported to the transporting section in the present invention is a vehicle, or the sludge heat recovery apparatus further comprises a sludge drying section and the means for transporting sludge transported to the sludge drying section is a vehicle.

The drying performed in the sludge drying section may be carbonization or simple drying without carbonization. A simple drying treatment without carbonization is preferred.
The sludge drying section is not particularly limited, and may be a carbonization type sludge drying section or a steam type sludge drying section. A steam type sludge drying section is preferred. It is more preferable that the sludge heat recovery device has a pipe for supplying (returning) the steam obtained from the solid fuel boiler to the sludge drying section, and the drying in the steam type sludge drying section is performed using the returned steam from the viewpoint of reducing CO ₂ emissions. In addition, you may heat using fossil fuels, such as heavy oil, auxiliary. The drying temperature is preferably 100 to 300°C, more preferably 120 to 200°C, and particularly preferably 140 to 160°C.
From the viewpoint of reducing CO ₂ emissions, it is preferable that the sludge heat recovery device has a wiring that supplies the power obtained from the generator to the sludge drying section, and that the returned power is used for drying and transportation in the sludge drying section.

It is preferable that the moisture content of the dried sludge is 5 to 40% by mass from the viewpoint of easy control of the net calorific value of the solid fuel. It is more preferably 20 to 40% by mass. More preferably, it is 25 to 35% by mass. Moisture content means a value obtained by holding 50 g of a measurement object (e.g., dried sludge) in an arbitrary dryer adjusted to 105 ° C. for 20 hours and calculating the mass reduced by this drying process as moisture.

<Conveyor>
In the present invention, the conveying section conveys at least the dried sludge to the solid fuel boiler.
It is preferable that the sludge heat recovery apparatus has at least the conveying section and the solid fuel boiler integrated in this order, from the viewpoint of reducing the conveying distance of the dried sludge and reducing the conveying cost and CO ₂ emissions. One end of the conveying section is preferably directly connected to the sludge drying section. It is also preferred that the other end of the conveying section is directly connected to the solid fuel boiler.
The conveying means of the conveying section is not particularly limited, but examples thereof include a belt conveyer, a screw feeder, an air blower (piping), a pump force feed, a road (vehicle), and the like. For example, it is preferably conveyed to the top of the solid fuel boiler by a conveyor. The conveyor is preferably an RPF conveyor or a coal conveyor from the viewpoint of cost reduction by utilizing existing equipment.
The conveyor is preferably a conveyor that is protected against corrosion by chlorine and the like. The RPF conveyer is usually made of plastic containing vinyl chloride to prevent corrosion from chlorine and the like. On the other hand, coal conveyors often lack sufficient corrosion protection against chlorine and the like. Therefore, it is preferable to use the RPF conveyer rather than the coal conveyer.
On the other hand, it is preferable that the conveying section and the solid fuel boiler, or the sludge drying section, the conveying section and the solid fuel boiler are located on the same site from the viewpoint of suppressing treatment costs. Also, the transport section is preferably not a public road, more preferably not a road. Therefore, it is preferable that the transportation means from the transportation section to the solid fuel boiler or the transportation means from the sludge drying section to the solid fuel boiler be other than a vehicle from the viewpoint of transportation cost and reduction of CO ₂ emissions.
However, the entire amount of dried sludge may not be conveyed to the solid fuel boiler via the conveying section. For example, between the sludge drying section and the conveying section or in the conveying section, a conveying port to the outside of the sludge heat recovery apparatus is provided, and part of the dried sludge is conveyed from the conveying port to the outside of the sludge heat recovery apparatus using a vehicle or the like.
From the viewpoint of reducing CO ₂ emissions, it is preferable that the sludge heat recovery device has wiring for supplying power obtained from the generator to the transport section, and that transport in the transport section is performed using the returned power.

It is preferred that the conveying section is preferably sealable from the conveying section to the solid fuel boiler, more preferably from the sludge drying section to the solid fuel boiler. By introducing the dried sludge into the solid fuel boiler in a sealed state, it is easier to control odor and dust when conveying the dried sludge.
The sealing means is not particularly limited, and examples thereof include a mode in which a cylindrical cover is provided to cover the conveying section, and a mode in which the inside is kept under negative pressure to prevent odor and dust from scattering.

(RPF input part)
It is preferable that the transport section 41 has an RPF input section and can mix the dry sludge 22 and the RPF 31 at a desired ratio.
Conveyor section 41 also preferably includes a coal input section so that dry sludge 22 and coal (not shown) can be mixed in desired proportions.
From the viewpoint of adjusting the dry sludge so that it easily satisfies Condition 1A, Condition 1B, or Condition 1C in the preferred embodiments described later, the RPF containing at least one of plastic, paper, and paper sludge, or coal, and dry sludge are more preferably conveyed to the solid fuel boiler. Here, it is preferable that the conveying unit conveys the dried sludge together with the coal to the solid fuel boiler by air current conveying. Specifically, it is preferable that the conveying section has dry sludge pulverization means, or further includes a sludge drying section, and the sludge drying section has dry sludge pulverization means. A crusher can be used as a crushing means. In addition, by conveying the dried sludge with an air current, the dried sludge can be pulverized to have a finer particle size. The average particle size of the dried sludge in the conveying section is not particularly limited, but is preferably 10 mm or less, more preferably 3 mm or less.

In a preferred embodiment of the present invention, when the total net calorific value of all fuels supplied to the solid fuel boiler is ^Q1 and the net calorific value of the dried sludge is ^Q2 , the dried sludge preferably satisfies Condition 1A, Condition 1B or Condition 1C below. By adjusting the solid fuel containing dried sludge so as to satisfy these conditions, it is possible to obtain a high amount of heat while adjusting the heat of vaporization when water becomes water vapor to achieve the same degree of combustion as coal.
Condition 1A: The moisture content of dried sludge is 20% by mass or less, and the value of 100%×Q ² /Q ¹ is 40% or less.
Condition 1B: The moisture content of the dried sludge is more than 20% by mass and 30% by mass or less, and the value of 100%×Q ² /Q ¹ is 20% or less.
Condition 1C: The moisture content of the dried sludge is more than 30% by mass and 40% by mass or less, and the value of 100%×Q ² /Q ¹ is 10% or less.
The calorific value can be measured by a combustion heat measuring device (manufactured by IKA, model "C5003").

RPF usually means a high-calorie solid fuel made from waste plastics and used paper, which are difficult to recycle, among industrial wastes. The RPF production raw material means a raw material whose main component is waste plastic or used paper that can be used to produce such a normal RPF, but it also includes RPF that is already in the form of solid fuel. In addition, the main component is plastic and / or paper (the total of plastic and paper is approximately 50 mass%
If it is a raw material with the above content ratio), it is included in the RPF manufacturing raw material.
The type of plastics (including waste plastics; the same shall apply hereinafter) that may be included in the RPF manufacturing raw material is not particularly limited, but those that do not generate toxic gases when burned are preferred. For example, polystyrene, polyethylene and polypropylene are preferably used. It is also preferable to use a chlorine-containing plastic such as vinyl chloride after taking measures against corrosion against chlorine or the like. In addition to plastics and paper (including used paper; the same shall apply hereinafter), raw materials for RPF production may include, for example, waste wood.

Paper sludge is wastewater treatment sludge (dehydrated sludge) from paper mills. The paper sludge may be thickened in a settling tank or rotary screen and dewatered in a screw press or belt filter before being used as another material. Paper sludge includes mixed sludge, which is a mixture of all wastewater treatment sludge generated in factories, sludge (DIP sludge) mainly composed of fibrous materials recovered from pulp-based wastewater in pressurized flotation equipment, simple sedimentation tanks, coagulating sedimentation tanks, fiber recovery equipment, etc. Excess sludge generated in activated sludge equipment, screen rejection, cleaner rejection, waste paper, coat break, dry break, or wet break in the papermaking process. For example, fibers recovered from wastewater without being screened include fibers less than 0.1 mm in length.
In the present invention, it is preferred to use an RPF manufacturing raw material comprising at least one of plastic, paper and paper sludge.

<Solid fuel boiler>
Preferably, the conveying section is connected to the top of the solid fuel boiler. For example, the conveying unit is preferably connected to an area within 30% of the height of the solid fuel boiler, more preferably connected to an area within 20% from the top, and particularly preferably connected to an area within 10% from the top.
The height of the solid fuel boiler is not particularly limited. For example, the lower limit is preferably 10 m or more, more preferably 20 m or more, and particularly preferably 40 m or more. For example, the upper limit is preferably 100 m or less, more preferably 80 m or less, and particularly preferably 60 m or less.

The solid fuel boiler is not particularly limited, and biomass boilers and fossil fuel boilers (especially coal boilers) can be mentioned. Preferably, the solid fuel boiler is a biomass boiler.
The combustion method of the solid fuel boiler is not particularly limited, and examples include a fluidized bed (fluidized bed) furnace, a stoker furnace, a melting furnace, a rotary kiln, and the like. Among these, the fluidized bed furnace is preferable from the viewpoint of maintenance. The fluidized bed furnace is more preferably a circulating fluidized bed furnace from the viewpoint of temperature control in the furnace.
A combination of two or more of these furnaces may be used as the solid fuel boiler. In that case, a combination of a fluidized bed furnace and a stoker furnace in this order is preferred.

(additional fuel injection part)
It is preferable that the solid fuel boiler 51 further comprises an input portion 52 for additional fuel.
Preferably, the additional fuel 53 includes at least one of coal, plastic, paper, wood chips and rubber. The additional fuel 53 may contain fiber waste and the like.
By charging the solid fuel 22 containing dried sludge and other additional fuel 53 into the solid fuel boiler 51, a high amount of heat can be obtained.

(Piping for supplying steam)
The sludge heat recovery device preferably has a pipe (not shown) for supplying (returning) steam 55 obtained from the solid fuel boiler 51 to the sludge drying section 11 . With this configuration, it is possible to reduce the acquisition cost of energy input for drying in the sludge drying section, improve energy efficiency, and reduce CO ₂ emissions.
If the solid fuel boiler is equipped with a generator, these pipes are preferably arranged so that the steam that has passed through the generator can be used.

(Generator)
Preferably, solid fuel boiler 51 further comprises a generator 56 . Steam 55 generated in solid fuel boiler 51 is preferably supplied to a turbine (not shown) of generator 56 and used for power generation.
Preferably, the sludge heat recovery device 101 supplies electric power 57 obtained from the generator 56 to the conveying section 41, or the sludge heat recovery device 101 is further provided with a sludge drying section 11 and supplies power to the sludge drying section 11. It is more preferable to supply to all of the sludge drying section 11 and the conveying section 41 .
With this configuration, it is possible to reduce the acquisition cost of the energy input for drying in the sludge drying section and the conveying section, improve energy efficiency, and reduce CO ₂ emissions.

<Other devices>
The sludge heat recovery device may have parts with other functions.
For example, a deodorizing unit for treating odor, a dust collection unit for treating dust, a temperature reduction tower, a reaction tower, an ash pit, an exhaust unit such as a chimney that can discharge exhaust to the outside, a heat exchange device, a noise reduction device, a deodorant spray device, etc. It is usually preferable.

In the sludge heat recovery system, it is preferable that all facilities constituting the sludge heat recovery system are located within the same administrative district.
By integrating the sewage treatment plant, the drying business, and the solid fuel boiler (equally connected, the owner and operator are the same), the sewage treatment sludge can be used as fuel for the solid fuel boiler without ever being treated as industrial waste.

[Sludge heat recovery system]
The sludge heat recovery system of the present invention includes the sludge heat recovery apparatus of the present invention and a sewage treatment plant, and either transports dry sludge made of sludge obtained at the sewage treatment plant to the transport section by vehicle, or the sludge heat recovery system further includes a sludge drying section, and the sludge obtained at the sewage treatment plant is transported to the sludge drying section by vehicle.
In FIG. 1 , the sludge-to-fuel system 102 includes a sludge-to-fuel device 101 and a sewage treatment plant 1 . For example, it is preferable to transport the sludge 3 obtained by the sludge dehydrator 2 of the sewage treatment plant 1 to the sludge drying section 11 by vehicle.
A normal sewage treatment plant can be used as the sewage treatment plant.
The sludge dehydrator is not particularly limited, and known devices can be used, including conventionally known centrifugal separators and dryers of indirect heating and reduced pressure heating. Examples of the dehydrator include screw presses, belt presses, belt filters, and centrifuges.

In the sludge heat recovery system of the present invention, the sludge heat recovery device and the sewage treatment plant are preferably located within the same administrative district.
When a public body has a sewage treatment plant, it is preferable that a business operator (e.g., a factory such as a paper mill, a power plant, etc.) lends the land for the solid fuel boiler portion to the public body having the sewage treatment plant (e.g., local governments such as the country, prefectures, or municipalities) and installs the sludge heat recovery apparatus of the present invention on the land (installing the sludge drying section and the conveying section).
The sludge heat recovery system of the present invention can efficiently link the sludge heat recovery device and the sewage treatment plant to efficiently recycle sludge as fuel. In addition, since it can be easily treated in a short time, it is possible to suppress the problem of odor generation due to putrefaction. Further, the heat generated by combustion in a solid fuel boiler can be utilized, for example, in other facilities that require heating.
Other facilities requiring such heating include factories (preferably paper mills), power plants, greenhouses for growing flowers and the like.
Other facilities that require heating are preferably located close to the sludge heat recovery equipment from the viewpoint of reducing the cost of using electric power and steam.

[Sludge heat utilization type factory]
The sludge heat utilization type plant of the present invention includes the sludge heat recovery apparatus of the present invention or the sludge heat recovery system of the present invention, and a plant, and has piping for supplying steam obtained from a solid fuel boiler to the plant, and the plant is a paper mill.
In FIG. 1 , sludge heat utilization type plant 103 comprises sludge heat recovery system 102 (including sludge heat recovery device 101 ) and plant 61 . For example, preferably, plant 61 is a paper mill, with piping (not shown) supplying steam 55 from solid fuel boiler 51 to plant 61 .
In the sludge heat utilization type plant 103 , the solid fuel boiler 51 is preferably further equipped with a generator 56 and power 57 obtained from the generator 56 is supplied to the plant 61 .

Integrating the sewage treatment plant, sludge drying section, conveying section, solid fuel boiler, and factory (equipmentally connecting them) contributes to advanced utilization of thermal energy.

1 Sewage treatment plant 2 Sludge dehydrator 3 Sludge 11 Sludge drying unit 12 Dried sludge 22 Solid fuel derived from dried sludge 31 RPF, coal 41 Transfer unit 51 Solid fuel boiler 52 Additional fuel input unit 53 Additional fuel 55 Steam 56 Generator 57 Electric power 61 Factory 101 Sludge heat recovery device 102 Sludge heat recovery system 103 Sludge heat utilization type factory

Claims (14)

A sludge heat recovery system comprising a sludge heat recovery device and a sewage treatment plant,
The sludge heat recovery device comprises at least a sludge drying section, a conveying section and a solid fuel boiler in this order,
Sewage sludge obtained at the sewage treatment plant is conveyed to the sludge drying unit by a vehicle,
The sludge supplied to the sludge drying unit includes the sewage sludge and paper sludge,
The sludge heat recovery device obtains dried sludge in the sludge drying section, and the conveying section conveys at least the dried sludge to the solid fuel boiler,
One end of the conveying unit is directly connected to the sludge drying unit, and the other end is directly connected to the solid fuel boiler,
The sludge heat recovery device is a sludge heat recovery system installed in a paper mill. The sludge heat recovery system according to claim 1, wherein the dry sludge has a moisture content of 5 to 40% by mass. 3. The sludge heat recovery system according to claim 1 or 2, wherein said conveying section conveys RPF or coal containing at least one of plastic, paper and paper sludge, and said dried sludge to said solid fuel boiler. The sludge heat recovery system according to any one of claims 1 to 3, wherein said paper sludge or said paper mill waste water treatment sludge comprises fibers of less than 0.1 mm in length recovered from waste water without being separated by a screen. The sludge heat recovery system according to any one of claims 1 to 4, wherein said conveying section has means for pulverizing said dried sludge, or said sludge drying section has said pulverizing means for said dried sludge. When the total net calorific value of all fuels supplied to the solid fuel boiler is Q ¹ and the net calorific value of the dried sludge is Q ² , the dried sludge satisfies the following condition 1A, condition 1B or condition 1C. The sludge heat recovery system according to any one of claims 1 to 5.
Condition 1A: The moisture content of dried sludge is 20% by mass or less, and the value of 100%×Q ² /Q ¹ is 40% or less.
Condition 1B: The moisture content of the dried sludge is more than 20% by mass and 30% by mass or less, and the value of 100%×Q ² /Q ¹ is 20% or less.
Condition 1C: The moisture content of the dried sludge is more than 30% by mass and 40% by mass or less, and the value of 100%×Q ² /Q ¹ is 10% or less. The sludge heat recovery system according to any one of claims 1 to 6, wherein the transport section transports the dry sludge together with the coal to the solid fuel boiler by airflow transport. the solid fuel boiler further comprising an input for additional fuel;
A sludge heat recovery system according to any preceding claim, wherein said additional fuel comprises at least one of coal, plastic, paper, wood chips and rubber. the solid fuel boiler further comprising a generator;
The sludge heat recovery system according to any one of claims 1 to 8, wherein electric power obtained from said generator is supplied to said conveying section or to said sludge drying section. The sludge heat recovery system according to any one of claims 1 to 9, comprising sealing means capable of sealing between said sludge drying section and said solid fuel boiler. A pipe that supplies steam obtained from the solid fuel boiler to the paper mill,
The sludge heat recovery system according to any one of claims 1 to 10. the solid fuel boiler further comprising a generator;
The sludge heat recovery system according to any one of claims 1 to 11, wherein electric power obtained from said generator is supplied to said paper mill. The sludge heat recovery system according to any one of claims 1 to 12, wherein the sludge heat recovery device and the sewage treatment plant are within the same administrative district. The sludge heat recovery system according to any one of claims 1 to 13, wherein the sludge drying section is a steam type sludge drying section, and has piping for supplying steam obtained from the solid fuel boiler to the sludge drying section.

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