CN117651831A - Sludge incineration system and sludge incineration method - Google Patents

Abstract

The invention provides a sludge incineration system and a sludge incineration method, which are not easy to cause blockage and erosion of a flow path of a heat exchanger. The above object is achieved by a sludge incineration system and a sludge incineration method, the sludge incineration system comprising: a circulating gas flowing in the circulation path; a dryer for drying the 1 st dehydrated sludge by heat of the circulating gas to obtain a dried sludge; a separator that separates the dried sludge from the recycle gas; an air preheater for exchanging heat between air supplied from the outside and high-temperature incineration exhaust gas generated by incinerating sludge to obtain preheated air; and a circulating gas heater for heating the circulating gas by exchanging heat between the circulating gas and the preheated air, and converting the circulating gas into a high-temperature circulating gas, wherein the circulating gas is discharged from the dryer together with the dried sludge, reaches the circulating gas heater via the separator, is heated, is supplied to the dryer again, and is circulated, and the dryer dries and pulverizes the 1 st dehydrated sludge into granular dry sludge.

Description

Sludge incineration system and sludge incineration method

Technical Field

The sewage treatment method generally performed in the sewage industry is as follows: sewage produced by people's living and public places is collected in a sewage pipe, and is treated with activated sludge in a sewage terminal treatment plant or the like. In this embodiment, sewage sludge such as raw sludge and surplus sludge is produced, and an incineration facility is provided for treating the sewage sludge. In an incineration facility, sewage sludge is treated by various incineration systems and incineration methods.

Patent document 1 discloses a technology related to a sludge incineration system, and aims to solve the problem of suppressing stagnation of supply of dry waste gas due to adhesion of tar to a supply means for supplying dry waste gas from a removal means for removing a predetermined substance from gas generated during drying of sludge to other equipment. Patent document 1 discloses a dryer as an element of the solution, which obtains a heat source from a heat exchanger for drying, the heat source being based on incineration exhaust gas generated in an incinerator.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2014-074538

Disclosure of Invention

Problems to be solved by the invention

However, in this heat exchanger system, since the incineration exhaust gas passes through the flow path in the heat exchanger, dust and tar contained in the incineration exhaust gas become a problem. If dust and tar adhere to and accumulate in the flow path in the heat exchanger, clogging and erosion may occur.

Accordingly, an object of the present invention is to provide a sludge incineration system and a sludge incineration method, which are less likely to cause clogging and erosion of a flow path of a heat exchanger.

Means for solving the problems

One embodiment of means for solving the above problems is as follows.

(mode 1)

A sludge incineration system that incinerates sludge, the sludge incineration system comprising: a circulating gas flowing in the circulation path; a dryer for drying the 1 st dehydrated sludge by heat of the circulating gas to obtain a dried sludge; a separator that separates the dried sludge from the recycle gas; an air preheater for exchanging heat between air supplied from the outside and high-temperature incineration exhaust gas generated by incinerating sludge to obtain preheated air; and a circulating gas heater for heating the circulating gas by exchanging heat between the circulating gas and the preheated air, and converting the circulating gas into a high-temperature circulating gas, wherein the circulating gas is discharged from the dryer together with the dried sludge, reaches the circulating gas heater via the separator, is heated, is supplied to the dryer again, and is circulated, and the dryer dries and pulverizes the 1 st dehydrated sludge into granular dry sludge.

In the conventional sludge incineration system disclosed in patent document 1, a heat source is obtained by heat exchange between the circulating gas supplied to the dryer and the incineration exhaust gas. In the aspect of the present invention, on the other hand, the circulating gas obtains a heat source from the circulating gas heater. The circulating gas heater has a flow path through which the preheated air as clean air flows and a flow path through which the circulating gas flows, and exchanges heat between these flow paths, so that dust and tar do not flow into the flow path through which the preheated air flows, and clogging, erosion, and the like of the flow path due to the dust and tar are less likely to occur.

Further, since the preheated air is supplied from the outside and the heat source for preheating is obtained from the air preheater through which the incineration exhaust gas flows, the temperature and flow rate of the circulating gas can be flexibly adjusted according to the operation condition of the sludge incineration system by adding a structure capable of increasing or decreasing the supply amount of the outside air.

(mode 2)

The sludge incineration system according to claim 1, wherein the dryer has: a tube extending in a circular shape; a sludge introducing portion for introducing the 1 st dehydrated sludge into the pipe; a gas supply unit that supplies a high-temperature circulating gas into the pipe; and a gas discharge unit for discharging the circulating gas containing the dry sludge from the pipe, wherein the high-temperature circulating gas supplied from the gas supply unit circulates at a high speed in the pipe and collides with the 1 st dehydrated sludge introduced from the sludge introduction unit.

As an example of the method for treating the 1 st dehydrated sludge, a method in which the water content is reduced to a concentration at which the sludge can be put into an incinerator and then the sludge is incinerated in the incinerator is given. In the dryer of the present embodiment, the high-temperature circulating gas circulates at a high speed in the pipe and continuously collides with the 1 st dehydrated sludge, so that the 1 st dehydrated sludge is crushed into granular dry sludge. The granular dry sludge is contained in the circulating gas and discharged from the gas discharge portion.

(mode 3)

The sludge incineration system according to the item 1, wherein the dried sludge produced by the dryer is sent to the separator together with the circulating gas.

Although various methods of transporting the dry sludge to the incinerator have been considered, in this embodiment, the dry sludge is transported together with the circulating gas, and therefore, it is not necessary to provide a separate transport facility or machine, and the dry sludge can be transported easily.

(mode 4)

The sludge incineration system according to claim 1, wherein the sludge incineration system comprises: a white smoke prevention preheater for exchanging heat between the air supply gas supplied from the white smoke prevention fan and the incineration exhaust gas passing through the air preheater to obtain high Wen Gongqi gas; and an exhaust gas heater that exchanges heat between the exhaust gas extracted from the circulating gas and the high-temperature supply gas to obtain a high-temperature exhaust gas, wherein the exhaust gas is extracted from a circulating path connecting the separator and the circulating gas heater and dehumidified, and the high-temperature exhaust gas is supplied to an incinerator that incinerates sludge.

It is necessary to pump a part of the circulating gas, but it has been difficult to treat the circulating gas (specifically, to remove odor and tar). In this embodiment, the dehumidified exhaust gas is subjected to heat exchange with the high-temperature supply gas to form a high-temperature exhaust gas, thereby suppressing adhesion and solidification of tar to the exhaust gas pipe. In addition, by adopting a structure in which the exhaust gas is supplied to the incinerator, the reduction of the sludge odor in the circulation path can be achieved.

(mode 5)

The sludge incineration system according to the 1 st aspect, wherein the sludge incineration system has: an incinerator that incinerates sludge; and a sludge feeder for feeding sludge into the incinerator, wherein the dried sludge separated by the separator is discharged to the sludge feeder, and the sludge feeder feeds the dried sludge and the 1 st dehydrated sludge to the incinerator.

When the sludge fed into the incinerator is only the 1 st dehydrated sludge, the sludge combustion in the incinerator becomes unstable according to the water content and the amount of the 1 st dehydrated sludge fed. According to this aspect, since the dry sludge is fed to the incinerator in addition to the 1 st dehydrated sludge, the water content of the whole incinerated sludge is reduced, and the combustion of the sludge can be stabilized.

(mode 6)

The sludge incineration system according to the 5 th aspect, wherein the 2 nd dewatered sludge is further fed into the incinerator.

When the 1 st dehydrated sludge and the dried sludge are fed into the incinerator from a single feeding line, dust explosion may be caused in the incinerator. In this embodiment, the 2 nd dehydrated sludge is additionally fed into the incinerator, so that dust explosion can be suppressed.

(mode 7)

The sludge incineration system according to claim 1, wherein the sludge incineration system is provided with an incinerator that incinerates sludge, a part of the preheated air is supplied to the incinerator through the circulating gas heater, and the remaining part of the preheated air is supplied to the incinerator without passing through the circulating gas heater.

The flow rate of the circulating gas flowing through the circulation path varies according to the operating conditions of the incinerator and the sludge incineration facility including the incinerator. When the flow rate of the circulating gas is small, if the preheated air continuously flows through the flow path in a constant amount, the circulating gas heater is in a so-called idle state, and the circulating gas heater may be a factor of wear and tear. According to this aspect, the surplus of the preheated air does not flow into the circulating gas heater, and therefore the circulating gas heater is not easily in a dead-burned state.

(mode 8)

The sludge incineration system according to claim 1, wherein the sludge incineration system has a control device that performs control as follows: the temperature of the circulating gas supplied to the dryer is measured to obtain a measured temperature, and a target temperature of the circulating gas supplied to the dryer is calculated based on the measured temperature, and the flow rate of the air supplied from the outside is increased or decreased so that the temperature of the circulating gas approaches the target temperature.

By providing the control device of the present embodiment, the temperature of the circulating gas supplied to the dryer falls back within a predetermined temperature range, and each device is less likely to be damaged or worn prematurely, and the running cost can be reduced.

(mode 9)

The sludge incineration system according to claim 2, wherein the dry sludge is not introduced into the dryer.

In the case of drying the 1 st dehydrated sludge, in the case of a conventional dryer, it may be difficult to dry or it takes a long time to dry depending on the concentration of the organic component and the water content, and thus the dried sludge and the 1 st dehydrated sludge are mixed as a mixture and subjected to a drying treatment. On the other hand, the inventors found that, in the case of the dryer according to aspect 2, even if the 1 st dehydrated sludge is not mixed with the dry sludge, the 1 st dehydrated sludge can be easily dried and pulverized by separately introducing the 1 st dehydrated sludge into the dryer. The mechanism is not clear, but it is considered that the high-temperature circulating gas collides with the 1 st dehydrated sludge, which is the object to be treated, at a high speed in succession.

(mode 10)

A method for incinerating sludge, comprising: a circulation step of circulating a gas in a circulation path; a drying step of drying the 1 st dehydrated sludge by heat of the circulating gas in a dryer to obtain a dried sludge; a separation step of separating the dried sludge from the recycle gas in a separator; a preheated air obtaining step of exchanging heat between air supplied from the outside and high-temperature incineration exhaust gas generated by incinerating sludge in a circulating gas heater to obtain preheated air; and a high-temperature circulating gas obtaining step of heating the circulating gas by exchanging heat between the circulating gas and the preheated air, and forming the circulating gas into a high-temperature circulating gas, wherein the circulating gas is discharged from the dryer together with the dried sludge, reaches the circulating gas heater via the separator, is heated, is supplied to the dryer again, and is circulated, and in the drying step, the 1 st dehydrated sludge is dried and crushed into dry sludge in the form of powder.

The same operational effects as those of the embodiment 1 can be expected.

Effects of the invention

According to the present invention, a sludge incineration system and a sludge incineration method are provided in which clogging and erosion of a flow path of a heat exchanger are not easily caused.

Drawings

Fig. 1 is a diagram showing an embodiment of the present invention.

Fig. 2 is a diagram showing details of the dryer.

Fig. 3 is a diagram showing an embodiment of the present invention.

Fig. 4 is a diagram showing an embodiment of the present invention.

Detailed Description

< embodiment 1 >

Next, a mode for carrying out the invention will be described. The present embodiment is an example of the present invention. The scope of the present invention is not limited to the scope of the present embodiment.

The sludge incineration system according to the present embodiment is characterized by comprising: a circulating gas flowing through the circulation paths (G1, G2, G3, G4, G5); a dryer 100 for drying the 1 st dehydrated sludge 5 by heat of the circulating gas to obtain a dried sludge; a separator 10 that separates the dried sludge from the recycle gas; an air preheater 40 for exchanging heat between air supplied from the outside and high-temperature incineration exhaust gas generated by incinerating sludge to obtain preheated air; and a circulating gas heater 30 for heating the circulating gas by exchanging heat between the circulating gas and the preheated air, and converting the circulating gas into a high-temperature circulating gas, wherein the circulating gas is discharged from the dryer 100 together with the dried sludge, reaches the circulating gas heater 30 via the separator 10, is heated, is supplied again to the dryer 100, and is circulated, and the dryer 100 dries and pulverizes the 1 st dehydrated sludge into granular dry sludge. An embodiment of the present invention will be described below with reference to fig. 1.

The dampers V1 to V7 shown below each have an opening/closing function for increasing/decreasing the flow rate of gas or air flowing through a pipe provided with each of the dampers V1 to V7.

The 1 st dehydrated sludge 5 carried in from the outside of the system is fed to the quantitative feeder 80, taken out in an appropriate amount, flowed through the sludge pipe 6, and introduced into the sludge feeder 19 to be fed to the incinerator 20. The 1 st dehydrated sludge may be directly introduced into the sludge feeder 19 (or the incinerator 20) without providing the sludge pipe 6 in particular. The quantitative feeder 80 is exemplified by a structure having two discharge portions, the 1 st discharge portion being connected to the sludge pipe 6 extending to the sludge feeder 19, and the 2 nd discharge portion being connected to the sludge pipe 7 extending to the hopper 90. The 1 st dehydrated sludge 5 is introduced from the quantitative feeder 80 into the incinerator 20 and the dryer 100, respectively. The 1 st dehydrated sludge 5 is not particularly limited, and is composed of, for example, a material obtained by dehydrating a mixture of raw sludge, surplus sludge, and the like generated in a sewage treatment plant, and means a material having a water content of 40% to 85%.

Although the details will be described later, the following structure may be constructed: the sludge pipe 6 is provided with a flow sensor F1 for measuring the flow rate of the 1 st dehydrated sludge flowing through the sludge pipe 6, and the arithmetic device 110 receives data of the measurement value of the flow sensor F1.

The sludge feeder 19 is a device for feeding the sludge introduced into the sludge feeder 19 into the sludge feeding portion 21 of the incinerator 20, and is a device for feeding the sludge into the sludge feeding portion 21 by, for example, a natural flow or a belt conveyor, a dosing machine, or the like. Examples of the sludge to be conveyed include the 1 st dehydrated sludge 5 and dried sludge.

(incinerator)

The sludge conveyed by the sludge feeder 19 is fed from the sludge feeder 21 into the incinerator 20. The incinerator 20 is a device for incinerating the input sludge. The incinerator 20 is not particularly limited, and may be exemplified by a fluidized incinerator, a circulating fluidized furnace, an arc furnace, and the like, and a pressurized fluidized incinerator is particularly preferred. The pressurized fluidized bed incinerator is configured to burn sludge by supplying the sludge to the pressurized fluidized bed incinerator, and to generate compressed air by rotationally driving a supercharger with incineration exhaust gas discharged from the fluidized bed incinerator, and to promote combustion by supplying the compressed air to the fluidized bed incinerator. The fluidized bed incinerator is a combustion furnace in which solid particles such as fluidized sand having a predetermined particle diameter are filled in the lower portion of the furnace as a fluidized medium, and the fluidized bed is maintained in a fluidized state by combustion air supplied into the furnace, and the sludge fed from the sludge feeding unit 21 and auxiliary fuel supplied as needed are combusted. An auxiliary fuel combustion device (not shown) for heating the flowing sand having a particle diameter of about 400-600 μm filled in the flowing incinerator is disposed at the lower part of the side wall, a starting burner (not shown) for heating the flowing sand at the time of starting is disposed at a position near the upper side of the auxiliary fuel combustion device, and a sludge input portion 21 is provided at a position above the starting burner. An air supply pipe 22 for supplying preheated air, which imparts oxygen required for combustion and kinetic energy for maintaining a flowing state of the fluidized bed, into the furnace is provided below the fluidized bed incinerator. The air supply pipe 22 may be a dispersion pipe in which a plurality of pipes having a plurality of openings are arranged, a dispersion plate in which a plurality of openings are provided in a plate-like iron plate, or the like. The high-temperature extraction gas passing through the extraction gas heater 70 described later may be supplied from the air supply pipe 22 into the furnace. In this case, for example, the high-temperature extraction gas is supplied into the furnace through an extraction gas pipe G8 connecting the extraction gas heater 70 and the air supply pipe 22. The incineration exhaust gas is combustion gas generated when the sludge is burned or gas obtained by mixing combustion gas with steam.

(air preheater)

The incineration exhaust gas generated in the incinerator 20 is discharged from the incinerator 20 at 800 to 900 ℃, flows through an incineration exhaust gas pipe 39 connecting the exhaust gas discharge portion of the incinerator 20 and the air preheater 40, and flows into the air preheater 40. The air preheater 40 has a flow path through which the incineration exhaust gas flows and a flow path through which air supplied from the outside flows, and heat exchange is indirectly performed between the two flow paths. The heat exchange method for the air preheater 40 is not particularly limited, but is preferably a tube type, and for example, a double tube type, a shell-and-tube type, or a spiral type may be used. The air supplied from the outside is supplied from the outside air at room temperature and the outside air temperature by the blower B2, flows through the air pipe A1, and flows into the air preheater 40, and the air pipe A1 connects the blower B2 to the base end of the flow path in the air preheater 40 through which the air supplied from the outside flows. The air pipe A1 may have a damper V2 for adjusting the supply amount of air. The air supplied from the outside is preheated by the air preheater 40, and flows out of the air preheater 40 as preheated air of 80 to 700 ℃, flows through an air pipe A2 connecting the circulating gas heater 30 and the air preheater 40, and flows into the circulating gas heater 30.

(white smoke prevention preheater)

The burned gas discharged from the air preheater 40 at 550 to 700 ℃ flows through the burned gas pipe 49 connecting the white smoke preventing preheater 50 and the air preheater 40, and flows into the white smoke preventing preheater 50. The white smoke prevention preheater 50 is used to prevent condensation and visualization of water vapor contained in the incineration exhaust gas generated during diffusion of the incineration exhaust gas discharged from the chimney of the incineration disposal facility in the atmosphere. The white smoke prevention preheater 50 is one type of heat exchanger in which heat exchange is indirectly performed between two flow paths, and the flow path is provided for the flow of the air supplied from the outside to the white smoke prevention preheater 50, that is, the supply gas, and the flow path is provided for the flow of the incineration exhaust gas. The heat exchange method for the air preheater 40 is not particularly limited, but is preferably a tube type, and for example, a double tube type, a shell-and-tube type, or a spiral type may be used. The air-supply gas flows into the white smoke prevention preheater 50 through an air pipe A7 connecting the white smoke prevention fan B3 and a base end of a flow path in the white smoke prevention preheater 50 through which the air-supply gas flows by a fan (also referred to as "white smoke prevention fan B3") that sends the outside air at room temperature and outside air temperature to the white smoke prevention preheater 50. The supplied gas passes through the white smoke prevention preheater 50 and exchanges heat with the incineration exhaust gas to obtain high Wen Gongqi gas heated to 200 to 400 ℃ and flows out of the white smoke prevention preheater 50. The high-temperature gas supply flows through the air pipe A8 connecting the white smoke prevention preheater 50 and the extraction gas heater 70, and flows into the extraction gas heater 70.

On the other hand, the burned gas cooled (cooled) to 200 ℃ to 600 ℃ by the white smoke prevention preheater 50 flows in the burned gas piping 59 and is sent to the burned gas treating apparatus 120.

(extraction gas Heater)

The high Wen Gongqi gas passing through the white smoke prevention preheater 50 flows through the air pipe A8 connecting the extraction gas heater 70 and the white smoke prevention preheater 50, and flows into the extraction gas heater 70. The extraction gas heater 70 exchanges heat between the extraction gas extracted from the circulation path and the high-temperature supply gas to obtain a high-temperature extraction gas. A damper V6 for adjusting the flow rate of the high Wen Gongqi gas flowing to the extraction gas heater 70 can be provided in the air pipe A8. The extraction gas heater 70 has a flow path through which the high-temperature supply gas flows and a flow path through which the extraction gas flows, and indirectly exchanges heat between the two flow paths. The pumping gas is a part of the circulating gas, and is a gas pumped out from the circulating path.

The circulating gas flowing through the circulation path contains tar and odor, and a part of the circulating gas may be extracted to remove tar and odor. Since the exhaust gas is led to the incinerator 20 for incineration treatment, the exhaust gas reduced in moisture (i.e., the dehumidified exhaust gas) is more suitable for incineration. Further, the extraction gas is preferably heated by heat exchange with the high-temperature supply gas in the extraction gas heater 70, and therefore, the extraction gas extracted from the section from the separator 10 in the circulation path to the circulation gas heater 30 is preferably used. In the case of the circulating gas in this region, the dry sludge is removed and the temperature is relatively low, so that there is an advantage in that an appropriate pumping gas can be pumped out.

The extraction gas extracted from the circulation path flows through extraction gas pipes G6 and G7 connecting the extraction gas heater 70 and the circulation path, and flows into the extraction gas heater 70. Since the extraction gas flowing into the extraction gas heater 70 is preferably dehumidified, a condenser 60 for dehumidifying the extraction gas may be provided between the extraction gas pipes G6 and G7, for example.

The high-temperature exhaust gas flows from the exhaust gas heater 70 at 80 ℃ or higher, more preferably 120 to 210 ℃, flows through the exhaust gas pipe G8 extending from the exhaust gas heater 70 to the incinerator 20, is sent to the incinerator 20, and is incinerated together with the sludge as an air fuel. If the extraction gas flowing out from the extraction gas heater 70 is lower than 350 ℃, tar contained in the extraction gas is liquefied and fixed to the pipe, and clogging may occur. Therefore, by increasing the temperature of the extraction gas, liquefaction of tar can be suppressed. Further, although the exhaust gas has tar and odor, which adversely affects each facility, the incineration treatment can eliminate the adverse effects of these as much as possible.

The high-temperature supply gas flows through the flow path through which the high-temperature supply gas flows, and is deprived of heat by the extraction gas, so that the high-temperature supply gas flows from the extraction gas heater 70 at 150 to 500 ℃, flows through the air pipe A9 connecting the extraction gas heater 70 and the chimney 130, and is guided to the chimney 130.

When the inflow amount of the extraction gas is small, if the high-temperature supply gas continuously flows in, the extraction gas heater 70 becomes high-heat, and a so-called idle burning state is established. To avoid this, a bypass air pipe a10 that discharges high Wen Gongqi gas from the air pipe A8 to the air pipe A9 and a damper V7 provided in the bypass air pipe a10 may be provided. The bypass air pipe a10 may be provided upstream of the damper V6 in the air pipe A8. By providing the bypass air pipe a10, the amount of the supply gas flowing to the white smoke prevention preheater 50 can be made sufficient, and a part of the high Wen Gongqi gas can be released to the air pipe A9 while the remaining part is supplied to the extraction gas heater 70. Thus, the flow rate of the high Wen Gongqi gas flowing into the pumping gas heater 70 can be adjusted in accordance with the flow rate of the pumping gas flowing into the pumping gas heater 70.

The extraction gas is a part of the circulating gas flowing through the circulating path.

(circulating gas Heater)

The preheated air preheated by heat exchange with the incineration exhaust gas in the air preheater 40 flows out of the air preheater 40, flows through the air pipes A2 and A3 connecting the circulating gas heater 30 and the air preheater 40 at 200 to 700 ℃, and flows into the circulating gas heater 30. The circulating gas heater 30 has a flow path through which the circulating gas flows and a flow path through which the preheated air flows, and indirectly exchanges heat between the two flow paths. The heat exchange method used in the circulating gas heater 30 is not particularly limited, and is preferably a tube type, for example, a double tube type, a shell-and-tube type, or a spiral type heat exchanger can be used, and among them, a shell-and-tube type heat exchanger is preferable. In the case of using the shell-and-tube heat exchanger, since the circulating gas contains dust, it is preferable that the circulating gas flows through a heat transfer tube in which dust is not easily accumulated, and the preheated air flows through the casing. The air pipe A2 is connected to the air pipe A3 to be integrated, and the preheated air continuously flows between the two pipes.

The air pipes A2 and A3 may be provided with a damper V1. The flow rate of the preheated air can be increased or decreased by the opening or closing operation of the damper V1, so that the heat obtained by the circulating gas can be adjusted by the circulating gas heater 30, and the temperature of the circulating gas can be controlled.

Further, an air pipe A4 branched from the air pipes A2 and A3 to flow the preheated air to the air supply pipe 22 of the incinerator 20 may be provided. The branching portion may be located upstream of the installation position of the damper V1 in the air pipes A2 and A3. Further, a damper V3 capable of adjusting the flow rate of the preheated air can be provided in the air pipe A4. By adopting this structure, a part of the preheated air is supplied to the incinerator through the circulating gas heater, and the remaining part is supplied to the incinerator without passing through the circulating gas heater.

The preheated air flowing out of the circulating gas heater 30 flows through the air pipe A5 connecting the incinerator 20 (the air supply pipe 22 in the case of the air supply pipe 22) and the circulating gas heater 30, and flows into the incinerator 20.

The circulating gas heater 30 of the present embodiment has a flow path through which preheated air, which is clean air, flows and a flow path through which circulating gas flows, and exchanges heat between these flow paths. Since the preheated air is obtained by preheating air supplied from the outside of the sludge incineration system, it is clean and free of dust and tar. Therefore, the flow path through which the preheated air flows does not flow in dust or tar, and clogging, erosion, and the like of the flow path due to dust or tar are less likely to occur.

(circulation path)

The circulation paths (G1, G2, G3, G4, G5) are paths through which the circulation gas flows, and include a path G4 connecting the dryer 100 to the separator 10, paths (G5, G1, G2) connecting the separator 10 to the circulation gas heater 30, and a path G3 connecting the circulation gas heater 30 to the dryer 100. In the circulation path, a blower B1 may be provided so as to flow the circulation gas. The location where the blower B1 is installed is preferably a flow path in which the circulating gas is not at a high temperature and does not contain dry sludge as much as possible, and for example, flow paths (G5, G1, G2) connecting the separator 10 and the circulating gas heater 30 are preferable. The flow paths G5, G1, and G2 are connected to each other so as to allow the circulating gas to flow.

The circulation gas may be configured such that the flow rate thereof is reduced by the extraction, and the external gas is introduced to supplement the flow rate. For example, the outside air introduction pipe G9 is connected to the upstream side of the installation position of the blower B1 in the flow paths (G5, G1, G2), and the outside air flows through the outside air introduction pipe G9 and is introduced into the circulation path.

The extraction gas pipe G6 may be provided in the flow paths (G5, G1, G2) so that the extracted extraction gas flows to the extraction gas heater 70. The connection point of the extraction gas pipe G6 to the flow paths (G5, G1, G2) is not particularly limited, and may be connected to a position upstream of the outside air introduction pipe G9 or to a position downstream of the blower B1.

A damper V5 may be provided in the extraction gas pipe G6. The opening and closing of the damper V5 is preferable because the flow rate of the extraction gas can be adjusted in accordance with the flow rate of the high Wen Gongqi gas flowing through the extraction gas heater 70.

(circulating gas)

The specific flow of the circulating gas will be described below. The temperature of the circulating gas shown below is an example. The external air introduced from the external air introduction pipe G9 flows as a circulating air through the flow paths (G5, G1, G2), and is heated by the circulating air heater 30, and flows out from the circulating air heater 30 at 300 to 500 ℃. The circulating gas (high-temperature circulating gas) flows through the flow path G3 and flows into the dryer 100.

The circulating gas contains the dried sludge generated in the dryer 100, flows out of the dryer 100 at 100 to 400 ℃ and flows through the flow path G4, and flows into the separator 10.

The recycle gas flowing into the separator 10 is separated into dry sludge in the separator 10, and the remainder flows out at 100 to 400 ℃ and reaches the flow paths (G5, G1, G2) again, thereby being recycled.

The flow rate of the circulating gas may be adjusted by a blower B1 provided in the circulation path, and the circulating gas may be circulated at least at a flow rate at which the dried sludge is not deposited in the circulation path.

A damper V4 for adjusting the flow rate of the circulating gas can be provided in the flow path G2.

(dryer)

The dryer 100 causes the 1 st dehydrated sludge fed from the hopper 90 to contact with the high-temperature circulating gas flowing in from the circulation path, and dries and pulverizes the 1 st dehydrated sludge to form granular dry sludge.

As the dryer 100, there may be exemplified: (1) A dryer in which the 1 st dehydrated sludge is dispersed in a high-temperature circulating gas and dried, such as a spray dryer, a pneumatic dryer, a fluidized bed dryer, and a rotary dryer; (2) A dryer of a type in which the 1 st dehydrated sludge is transported while being left standing, and the 1 st dehydrated sludge is brought into contact with a high-temperature circulating gas during the transport, such as a vent belt dryer, a tunnel dryer (parallel flow belt dryer), and an ejection flow dryer, and dried; (3) A dryer of a system in which the 1 st dehydrated sludge is dried by bringing a high-temperature circulating gas into contact with the 1 st dehydrated sludge while mechanically stirring the 1 st dehydrated sludge, as in a stirring dryer or the like.

The pneumatic dryer may be of various types, but a pneumatic dryer without a pulverizer for pulverizing the 1 st dehydrated sludge may be used.

In fig. 1 and 2, as the dryer 100, an air dryer is shown. The pneumatic dryer is configured to include: a tube 100B extending in a circular ring shape; a sludge introducing portion 100E for introducing the 1 st dehydrated sludge into the pipe 100B; a gas supply unit 100A for supplying a high-temperature circulating gas into the pipe 100B; and a gas discharge unit 100F for discharging a circulating gas containing the dry sludge from the pipe 100B, wherein the high-temperature circulating gas supplied from the gas supply unit 100A circulates at a high speed in the pipe 100B and collides with the 1 st dehydrated sludge introduced from the sludge introduction unit 100E. The tube 100B is composed of a tube portion 100Ba horizontally extending and connected to the gas supply portion 100A, a tube portion 100Bb bent and extending upward from the tube portion 100Ba, a tube portion 100Bc bent and extending in a direction folded back from the tube portion 100Bb (a direction parallel to the tube portion 100 Ba), and a tube portion 100Bd bent and extending downward from the tube portion 100 Bc. The pipe portion 100Bd is provided with a distal end portion 100C that is engaged with the distal end portion 100D of the gas supply portion 100A and receives the supply of the high-temperature circulating gas flowing through the gas supply portion 100A. The sludge introducing portion 100E is provided in the pipe 100B, particularly in the pipe portion 100Ba, and the gas discharging portion 100F is provided in the pipe 100B.

The high-temperature circulating gas is supplied to the gas supply unit 100A through the flow path G3. The 1 st dehydrated sludge introduced into the pipe 100B from the sludge introducing portion 100E through the sludge piping 4 is introduced into the high-temperature circulating gas circulating in the pipe portion 100Ba, continuously collides with the high-temperature circulating gas, and is blown off, dispersed and dried in the pipe 100B to become granular dry sludge. At this time, the high-temperature/high-speed circulating gas collides with the larger sludge particles of the 1 st dehydrated sludge, and breaks into a plurality of smaller sludge particles, and the moisture contained in the inside thereof evaporates rapidly.

The sludge particles having a particle size of not larger than a certain level, which are dispersed and dried, are contained in the flow of the circulating gas from the gas discharge unit 100F, and are discharged as dried sludge to the outside of the pneumatic dryer. On the other hand, sludge particles having a relatively large particle size, which are not sufficiently dispersed/dried, are not discharged from the gas discharge portion 100F, but are repeatedly circulated in the pipe 100B until they are sufficiently dispersed/dried. Thus, the pneumatic dryer mainly discharges the dried sludge of the sufficiently dispersed/dried powder particles. Specifically, the high-temperature circulating gas is supplied from the gas supply unit 100A to the pipe 100B, circulates through the pipe portions 100Ba, 100Bb, 100Bc, 100Bd, and 100Ba together with the sludge particles, and is partially discharged from the gas discharge unit 100F to the outside of the dryer 100. On the other hand, the high-temperature circulating gas that is not discharged is merged with the high-temperature circulating gas newly fed from the gas supply unit 100A, mixed, and flows through the pipe portions 100Ba, 100Bb, 100Bc, and 100Bd, and a part thereof is discharged from the gas discharge unit 100F to the outside of the dryer 100. As described above, a part of the high-temperature circulating gas is discharged from the gas discharge portion 100F, and the remaining part of the high-temperature circulating gas circulates in the pipe 100B. Thus, the newly introduced 1 st dehydrated sludge and the 1 st dehydrated sludge circulated in the pipe 100B are mixed in the pipe, circulated, dried, and pulverized.

In the operation of the pneumatic dryer, it is preferable that the flow rate of the high-temperature circulating gas flowing through the gas supply unit 100A of the pneumatic dryer is 20m/s to 60m/s, and the flow rate in the pipe 100B is 15m/s to 45 m/s. When the flow rate of the gas supply unit 100A and the pipe 100B is lower than the above value, the sludge particles are difficult to circulate in the pneumatic dryer, and there is a possibility that the drying process and the discharge to the outside of the circulator are hindered. In order to smoothly circulate the sludge particles, the flow rate in the pipe 100B is more preferably 15m/s or more.

It is particularly preferable to make the flow rate of the gas supply portion 100A faster than the flow rate of the tube 100B. By setting the speed difference, the newly supplied high-temperature circulating gas continuously collides with the circulated sludge particles, thereby promoting the dispersion of the sludge particles.

The high-temperature circulating gas to be circulated in the dryer 100 is preferably 300 to 500 ℃, more preferably 350 to 450 ℃, and even more preferably 400 ℃. In the case where the temperature of the high-temperature circulating gas is lower than this range, it takes much time to dry. On the other hand, setting the temperature higher than this range has a small advantage in that a large amount of energy is consumed to set the temperature to a high temperature, but there is a disadvantage in that the cost performance of the facility operation is lowered.

In addition, as equipment other than the above-described pneumatic dryer, the capacity of auxiliary machines is increased, and periodic maintenance and replacement of the crusher are required, but even if the pneumatic dryer with the crusher is provided, the same effects as those of the pneumatic dryer described above can be obtained.

The circulating gas containing the dried sludge flowing out from the dryer 100 is deprived of heat by the drying of the 1 st dehydrated sludge in the dryer 100 to be 100 to 400 ℃. The dried sludge produced by the dryer 100 is sent to the separator 10, but if it is sent to the separator 10 together with the recycle gas, for example, it is preferable that there is no need to have an additional facility for the sending. The circulating gas containing the dried sludge flows through a flow path G4 connecting the gas discharge portion 100F of the dryer 100 and the inflow portion of the circulating gas in the separator 10, and is supplied to the separator 10.

The water content of the dried sludge discharged from the dryer 100 is 1% to 40%.

(separator)

The separator 10 gas-solid separates the recycle gas containing the dry sludge supplied from the flow path G4, removes the dry sludge, and discharges the remaining portion to the flow path G5. The separator 10 includes: a sludge supply unit that receives a supply of a circulating gas containing dry sludge; a sludge discharge unit 11 for discharging the separated dry sludge; and a gas discharge unit for discharging the surplus of the circulating gas from which the dried sludge has been separated, to the flow path G5, and discharging the separated dried sludge from the separator 10, for example, to the sludge charging machine 19. The separated dry sludge may be naturally dropped from the sludge discharge portion 11 and supplied to the sludge charging machine 19, or a sludge pipe 3 connecting the sludge discharge portion 11 and the sludge charging machine 19 may be provided, and the separated dry sludge may be supplied to the sludge charging machine 19 through the sludge pipe 3.

Examples of the separator 10 include a gravity settling chamber for collecting dust by gravity, a mist separator for collecting dust by inertia, a cyclone separator for collecting dust by centrifugal force, a venturi cleaner for collecting dust by cleaning, a bag filter for collecting dust by filter cloth, a moving particle layer air filter for collecting dust by a packed layer, and an electric dust collector for collecting dust by electricity.

The separator 10 may be disposed immediately above the sludge feeder 19, and the separated dry sludge may be discharged from the sludge discharge portion 11 of the separator 10 to the sludge feeder 19. Since the dry sludge has a light weight and a strong sludge odor, the dry sludge is scattered when the transport path is long distance, and the sludge odor floats around. Therefore, if the dry sludge is discharged from the sludge discharge portion of the separator to the sludge feeder located immediately below, the dry sludge is rapidly fed into the incinerator, and therefore scattering of the dry sludge and emission of odor thereof can be suppressed as much as possible.

(1 st dehydrated sludge)

The 1 st dehydrated sludge 5 is temporarily stored in the quantitative feeder 80, flows in a suitable amount through the sludge pipe 7 connecting the hopper 90 and the quantitative feeder 80, and flows into and is stored in the hopper 90. The sludge stored in the hopper 90 flows through the sludge pipe 4 connecting the sludge introduction portion 100E of the dryer 100 and the hopper 90, and is introduced into the dryer 100.

The hopper 90 may receive the dry sludge separated by the separator 10, in addition to the 1 st dehydrated sludge. The dry sludge separated by the separator 10 may be manually fed into the hopper 90, or a sludge pipe 9 connecting the hopper 90 and the separator 10 may be provided, and the dry sludge may be fed into the hopper 90 by flowing into the sludge pipe 9. Thus, the 1 st dehydrated sludge and the dried sludge are mixed in the hopper 90. The 1 st dehydrated sludge may be difficult to dry or require a long time to dry depending on the concentration of organic components and the water content. By introducing the mixture of the 1 st dehydrated sludge and dried sludge into the dryer 100, drying of the mixture is promoted, and thus it is easily crushed.

(control)

In order to control the operation of the sludge incineration system according to the present embodiment, a control device using the computing device 110 may be provided. In order to perform this control, a temperature sensor and a flow sensor are provided at each place of the sludge incineration system. Details are described below.

As the temperature sensor, for example, a temperature sensor T1 for measuring the temperature of the incineration exhaust gas flowing through the incineration exhaust gas pipe 39, a temperature sensor T2 for measuring the temperature of the inside of the incinerator 20, a temperature sensor T3 for measuring the temperature of the circulating gas flowing through the flow paths G1 and G2, a temperature sensor T4 for measuring the temperature of the circulating gas flowing through the flow path G4, and a temperature sensor T5 for measuring the temperature of the high-temperature circulating gas flowing through the flow path G3 can be provided.

As the flow rate sensor, for example, a flow rate sensor F1 for measuring the flow rate of the 1 st dehydrated sludge flowing through the sludge pipe 6, a flow rate sensor F2 for measuring the flow rate of the 1 st dehydrated sludge flowing through the sludge pipe 7, and a flow rate sensor F3 for measuring the flow rate of the circulating gas flowing through the flow paths G1 and G2 may be provided.

The data of the measured temperatures of the temperature sensors T1 to T5 and the data of the measured flow rates of the flow sensors F1 to F3 are transmitted to the arithmetic device 110 in a wired or wireless manner. The computing device 110 computes the output values of the respective openings of the dampers V1 to V7 using a preset computing formula based on the received input values of the respective data of the measured temperature and the respective data of the measured flow rate. The computing device 110 transmits the output value to the dampers V1 to V7. The actuators provided in the dampers V1 to V7 are operated to open or close the valves and change the flow rate so that the current opening degree becomes the opening degree of the received output value. The calculation formula is not particularly limited, and may be constructed based on data of the past measured temperature, data of the measured flow rate, and data of the opening degree, for example, by a method of least squares control, PI control, PDI control, neural network control, or manual input.

As the control device, for example, a control device that performs the following control is given: the temperature of the circulating gas supplied to the dryer 100 is measured to obtain a measured temperature, and a target temperature of the circulating gas supplied to the dryer 100 is calculated based on the measured temperature, and the flow rate of the air supplied from the outside is increased or decreased so that the temperature of the circulating gas approaches the target temperature. Here, the control for increasing or decreasing the flow rate of the air supplied from the outside means, for example, that when the sludge incineration system is operated in a state where the throttle V2 has a specific opening (actual opening), the measured temperature is inputted as an input value to a preset operation expression to obtain a target opening of the throttle V2 as an output value, and the actual opening of the throttle V2 is brought close to the target opening obtained as the output value, whereby the flow rate of the air supplied from the outside is increased or decreased. Based on this control, the flow rate of the preheated air flowing into the circulating gas heater 30 increases or decreases, and the temperature of the circulating gas subjected to heat exchange increases or decreases.

Further, as another control device, for example, a control device that performs the following control can be cited: the flow rate of the circulating gas flowing through the flow path G2 is measured to obtain a measured flow rate, and the target flow rate of the circulating gas flowing through the flow path G2 is calculated based on the measured flow rate, and the flow rate of the circulating gas is increased or decreased so that the flow rate of the circulating gas approaches the target flow rate. Here, the control for increasing or decreasing the flow rate of the circulating gas means, for example, that when the sludge incineration system is operated in a state where the throttle valve V5 has a specific opening (actual opening), the measured flow rate is inputted as an input value to a preset operation expression to obtain a target opening of the throttle valve V5 as an output value, and the actual opening of the throttle valve V5 is brought close to the target opening obtained as the output value, whereby the flow rate of the circulating gas is increased or decreased. Based on this control, the flow rate of the circulating gas passing through the circulating gas heater 30 increases or decreases, and the temperature of the circulating gas flowing into the dryer 100 increases or decreases.

Further, the following apparatus can be employed: based on the data of the measured temperatures of the temperature sensors T1 to T5 and the data of the measured flow rates of the flow rate sensors F1 to F3, a target input amount of the 1 st dehydrated sludge to be introduced into the dryer 100 and a target input amount of the 1 st dehydrated sludge to be input into the incinerator 20 are calculated, and the discharge amount of the dehydrated sludge in the quantitative feeder 80 is controlled so as to be the target input amount and the target input amount.

< embodiment 2 >

As described above, the embodiment of the present invention has been described, but as shown in fig. 3, the following embodiment 2 (specifically, a sludge incineration system in which a feature that the dry sludge is not introduced into the dryer is added to the sludge incineration system of embodiment 2) is also a preferable embodiment based on this embodiment. Fig. 3 is a system diagram in which the sludge piping 9 shown in fig. 1 is not provided. In the conventional dryer, the dry sludge is also introduced together with the 1 st dehydrated sludge, but the dryer having the characteristics of this embodiment adopts a structure in which the high-temperature circulating gas is circulated in the dryer, and the 1 st dehydrated sludge is easily dried even if the dry sludge is not actively introduced. Therefore, there is an advantage that a piping or the like for guiding the dried sludge to the dryer is not required, and the overall form of the sludge incineration system is compact.

< embodiment 3 >

As shown in fig. 4, embodiment 3 below is also preferable. Specifically, the sludge incineration system according to claim 1 further includes an incinerator 20 for incinerating sludge, and the 2 nd dehydrated sludge is introduced into the incinerator 20 in addition to the 1 st dehydrated sludge.

The 2 nd dehydrated sludge 1 carried in from the outside of the system is fed into the sludge hopper 140. The sludge hopper 140 is provided with a sludge discharge portion, and the sludge discharge portion and the sludge feeder 19 are connected by a sludge pipe 2. The 2 nd dehydrated sludge 1 discharged from the sludge discharge unit flows into the sludge feeder 19 through the sludge pipe 2.

In this embodiment, examples of the sludge fed by the sludge feeder 19 include the 1 st dehydrated sludge 5, the 2 nd dehydrated sludge, and the dried sludge. The 2 nd dehydrated sludge 1 and the 1 st dehydrated sludge 5 are both dehydrated sludge and are fed as separate bodies into the incinerator 20. The entire amount of the 2 nd dehydrated sludge 1 is fed into the incinerator 20. When the 1 st dehydrated sludge 5 is incinerated only, the spontaneous combustion of the incinerator 20 may be unstable depending on the property, organic component concentration, and water content of the 1 st dehydrated sludge 5, and the 2 nd dehydrated sludge may be introduced in addition to the dried sludge, whereby the incinerator 20 can stably sustain combustion.

The sludge incineration system according to the following embodiment is also preferable based on embodiment 1 to embodiment 3 described above. For example, the sludge incineration system includes: a white smoke prevention preheater 50 for exchanging heat between the air supply gas supplied from the white smoke prevention fan B3 and the incineration exhaust gas passing through the air preheater 40 to obtain high Wen Gongqi gas; and an extraction gas heater 70 that exchanges heat between the extraction gas extracted from the circulating gas and the high-temperature gas supply gas to obtain a high-temperature extraction gas extracted from the circulation paths (G5, G1, G2) connecting the separator 10 and the circulating gas heater 30 and dehumidified, and the high-temperature extraction gas is supplied to the incinerator 20 that incinerates sludge. In the case of this sludge incineration system, it is preferable to suppress adhesion and solidification of tar to the exhaust gas pipe. Further, by adopting a configuration in which the exhaust gas is supplied to the incinerator 20, the sludge odor in the circulation path can be reduced.

The sludge incineration method using the above-described embodiment can be exemplified by the following method.

The sludge incineration method for incinerating sludge is characterized by comprising the following steps:

(1) A circulation step in which a circulation gas flows through circulation paths (G1, G2, G3, G4, G5);

(2) A drying step of drying the 1 st dehydrated sludge 5 by heat of the circulating gas in the dryer 100 to obtain a dried sludge;

(3) A separation step of separating the dried sludge from the recycle gas in the separator 10;

(4) A preheated air obtaining step of exchanging heat between air supplied from the outside and high-temperature incineration exhaust gas generated by incinerating sludge in the circulating gas heater 30 to obtain preheated air; and

(5) A high-temperature circulating gas obtaining step of heat-exchanging the circulating gas with the preheated air to heat the circulating gas, thereby converting the circulating gas into a high-temperature circulating gas,

the circulating gas is discharged from the dryer 100 together with the dried sludge, reaches the circulating gas heater 30 through the separator 10, is heated, is supplied again to the dryer 100, and is circulated, and in the drying step, the 1 st dehydrated sludge is dried and pulverized into granular dried sludge.

(others)

The granular dry sludge is difficult to strictly define, but is, for example, a dry sludge of a size such that when air having a flow rate of 20 m/sec is caused to flow through a pipe, the air smoothly flows together with the flow of the air.

The main lines shown in the drawing are indicated by solid lines for pipes through which the circulating gas and the pumping gas flow, by thick solid lines for pipes through which the incineration exhaust gas flows, by one-dot chain lines for pipes through which the 1 st dehydrated sludge/dried sludge/2 nd dehydrated sludge flow, by dashed lines for pipes through which the air/preheated air/supplied gas/high Wen Gongqi gas supplied from the outside flows, and by dashed lines for transmission/reception networks of the temperature sensor/flow sensor/damper and the arithmetic device.

Industrial applicability

The present invention can be used as a sludge incineration system and a sludge incineration method.

Description of the reference numerals

1: 2 nd dehydrated sludge; 5: 1 st dehydrated sludge; 10: a separator; 30: a circulating gas heater; 40: an air preheater; 100: a dryer; g1: a circulation path; and G2: a circulation path; and G3: a circulation path; and G4: a circulation path; and G5: a circulation path.

Claims (10)

1. A sludge incineration system for incinerating sludge is characterized in that,

the sludge incineration system comprises:

a circulating gas flowing in the circulation path;

a dryer for drying the 1 st dehydrated sludge by heat of the circulating gas to obtain a dried sludge;

a separator that separates the dried sludge from the recycle gas;

An air preheater for exchanging heat between air supplied from the outside and high-temperature incineration exhaust gas generated by incinerating sludge to obtain preheated air; and

a circulating gas heater for heating the circulating gas by exchanging heat between the circulating gas and the preheated air to thereby convert the circulating gas into a high-temperature circulating gas,

the circulating gas is discharged from the dryer together with the dried sludge, reaches the circulating gas heater through the separator to be heated, is supplied to the dryer again to be circulated,

the dryer dries and pulverizes the 1 st dehydrated sludge into powdery dry sludge.

2. The sludge incineration system as claimed in claim 1, wherein,

the dryer has:

a tube extending in a circular shape;

a sludge introducing portion for introducing the 1 st dehydrated sludge into the pipe;

a gas supply unit that supplies a high-temperature circulating gas into the pipe; and

a gas discharge unit for discharging a circulating gas containing the dry sludge from the pipe,

the high-temperature circulating gas supplied from the gas supply unit circulates at a high speed in the pipe and collides with the 1 st dehydrated sludge introduced from the sludge introduction unit.

3. The sludge incineration system as claimed in claim 1, wherein,

the dried sludge produced by the dryer is conveyed to the separator together with the recycle gas.

4. The sludge incineration system as claimed in claim 1, wherein,

the sludge incineration system comprises:

a white smoke prevention preheater for exchanging heat between the air supply gas supplied from the white smoke prevention fan and the incineration exhaust gas passing through the air preheater to obtain high Wen Gongqi gas; and

an extraction gas heater for exchanging heat between the extraction gas extracted from the circulating gas and the high-temperature supply gas to obtain a high-temperature extraction gas,

the pumping gas is a dehumidified gas pumped from a circulation path connecting the separator and a circulation gas heater,

the high temperature exhaust gas is supplied to an incinerator for incinerating sludge.

5. The sludge incineration system as claimed in claim 1, wherein,

the sludge incineration system comprises:

an incinerator that incinerates sludge; and

a sludge feeder for feeding sludge into the incinerator,

the dry sludge separated by the separator is discharged to the sludge feeder,

the sludge feeder feeds the dry sludge and the 1 st dehydrated sludge to the incinerator.

6. The sludge incineration system as claimed in claim 5, wherein,

the sludge incineration system also inputs the No. 2 dewatered sludge into the incinerator.

7. The sludge incineration system as claimed in claim 1, wherein,

the sludge incineration system is provided with an incinerator for incinerating sludge,

a part of the preheated air is supplied to the incinerator through the circulating gas heater, and the remaining part of the preheated air is supplied to the incinerator without passing through the circulating gas heater.

8. The sludge incineration system as claimed in claim 1, wherein,

the sludge incineration system is provided with a control device, and the control device performs the following control: the temperature of the circulating gas supplied to the dryer is measured to obtain a measured temperature, and a target temperature of the circulating gas supplied to the dryer is calculated based on the measured temperature, and the flow rate of the air supplied from the outside is increased or decreased so that the temperature of the circulating gas approaches the target temperature.

9. The sludge incineration system as claimed in claim 2, wherein,

the dried sludge is not introduced into the dryer.

10. A sludge incineration method for incinerating sludge is characterized in that,

The sludge incineration method comprises the following steps:

a circulation step of flowing a circulation gas in a circulation path;

a drying step of drying the 1 st dehydrated sludge by heat of the circulating gas in a dryer to obtain a dried sludge;

a separation step of separating the dried sludge from the recycle gas in a separator;

a preheated air obtaining step of exchanging heat between air supplied from the outside and high-temperature incineration exhaust gas generated by incinerating sludge in a circulating gas heater to obtain preheated air; and

a high-temperature circulating gas obtaining step of heat-exchanging the circulating gas with the preheated air to heat the circulating gas, thereby converting the circulating gas into a high-temperature circulating gas,

the circulating gas is discharged from the dryer together with the dried sludge, reaches the circulating gas heater through the separator to be heated, is supplied to the dryer again to be circulated,

in the drying step, the 1 st dehydrated sludge is dried and pulverized into a granular dry sludge.