WO2023026370A1 - Sludge incineration system and sludge incineration method - Google Patents

Abstract

[Problem] A problem is to provide a sludge incineration system and a sludge incineration method in which a flow path of a heat exchanger is less likely to be clogged or eroded. [Solution] The problem is solved by a sludge incineration system including circulating gas flowing in a circulation path, a dryer that dries a first dehydrated sludge with the heat of the circulating gas to obtain dried sludge, a separator that separates the dried sludge and the circulating gas, an air preheater that exchanges heat between the air supplied from the outside and high-temperature incineration exhaust gas generated by incinerating the sludge to obtain preheated air, and a circulating gas heater that heats the circulating gas by heat exchange with the preheated air to obtain high-temperature circulating gas, the sludge incineration system being characterized in that the circulating gas is circulated by being discharged from the dryer together with the dried sludge, passing through the separator, reaching the circulating gas heater to be heated therein, and being resupplied to the dryer, and the dryer dries and pulverizes the first dehydrated sludge into powdery dry sludge. The problem is also solved by the corresponding sludge incineration method.

Description

Sludge incineration system and sludge incineration method

The sewage treatment method that is usually used in sewage projects is to collect sewage generated by people's lives and businesses into sewage pipes and treat it with activated sludge at sewage treatment plants. In this system, sewage sludge such as raw sludge and surplus sludge is generated, and an incineration facility is provided to treat this sewage sludge. Incineration plants treat sewage sludge by various incineration systems and methods.

Patent Document 1 discloses a technology related to a sludge incineration system, and the problem to be solved is that tar is present in a supply means for supplying dry exhaust gas from a removal means for removing a predetermined substance from gas generated during drying of sludge to other equipment. It is supposed to suppress the stagnation of dry exhaust gas supply due to adhesion. Patent Document 1 shows a dryer as one element of the solution, but this dryer obtains a heat source from a heat exchanger for drying, and this heat source is based on the incineration exhaust gas generated in the incinerator. It's becoming

JP 2014-074538 A

However, in the form of the heat exchanger, the incineration exhaust gas passes through the flow path in the heat exchanger, so dust and tar contained in the incineration exhaust gas pose a problem. Dust and tar may cause clogging or erosion if they adhere or accumulate in the flow paths in the heat exchanger.

Therefore, the problem to be solved by the present invention is to provide a sludge incineration system and a sludge incineration method that are less likely to clog or erode the flow path of the heat exchanger.

One aspect of the means for solving the above problems is as follows.
(First aspect)
In a sludge incineration system that incinerates sludge,
a circulating gas flowing through the circulating path;
a dryer that dries the first dehydrated sludge with the heat of the circulating gas to obtain dried sludge;
a separator for separating the dried sludge and the circulating gas;
an air preheater that exchanges the heat of the air supplied from the outside with the high-temperature incineration exhaust gas generated by incinerating the sludge and converts it into preheated air;
a circulating gas heater that heats the circulating gas by exchanging heat with the preheated air to produce a high-temperature circulating gas,
The circulating gas is discharged from the dryer together with the dried sludge, passes through the separator, reaches the circulating gas heater, is heated, and is supplied to the dryer again for circulation,
The dryer dries and pulverizes the first dewatered sludge into powdery dried sludge.
A sludge incineration system characterized by:

In the conventional sludge incineration system disclosed in Patent Document 1, the circulating gas supplied to the dryer obtains a heat source through heat exchange with the incineration exhaust gas. On the other hand, in an aspect of the invention, the circulating gas derives its heat source from the circulating gas heater. The circulating gas heater has a channel through which preheated air, which is clean air, flows and a channel through which circulating gas flows. Heat is exchanged between these channels. Since tar does not flow in, clogging or erosion of the flow path due to dust or tar is unlikely to occur.

In addition, the preheated air is supplied from the outside, and the heat source used 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 operating conditions of the sludge incineration system.

(Second aspect)
The dryer is
A pipe extending in an annular shape, a sludge introduction part into which the first dewatered sludge is introduced into the pipe, a gas supply part into which high temperature circulation gas is supplied into the pipe, and a circulation gas containing dried sludge is supplied to the pipe. a gas discharge part discharged from the pipe,
The high-temperature circulating gas supplied from the gas supply unit circulates at high speed in the pipe and collides with the first dehydrated sludge introduced from the sludge introduction unit.
A sludge incineration system of the first aspect.

One example of a method for treating the first dewatered sludge is to reduce the water content to a concentration that can be put into the incinerator, and then incinerate it in the incinerator. In the dryer of this aspect, the high-temperature circulating gas circulates in the pipe at high speed and continues to collide with the first dehydrated sludge, so that the first dehydrated sludge is pulverized into powdery dried sludge. Powdery dry sludge is discharged from the gas discharge part while being contained in the circulating gas.

(Third aspect)
Dried sludge generated in the dryer is transported to the separator together with the circulating gas,
A sludge incineration system of the first aspect.

Various methods of transporting the dried sludge to the incinerator are conceivable, but in this embodiment, the dried sludge is transported together with the circulating gas, so there is no need to install separate transportation facilities or equipment, and the dried sludge can be easily transported. .

(Fourth aspect)
a white smoke prevention preheater that exchanges heat with the incineration exhaust gas that has passed through the air preheater to convert the air supply gas supplied from the white smoke prevention fan into high-temperature supply air;
a bleed gas heater that heat-exchanges the bleed gas bled from the circulating gas with the high-temperature supply gas to produce a high-temperature bleed gas,
The bleed gas is dehumidified by bleed from a circulation path connecting the separator and the circulating gas heater,
The high temperature extraction gas is supplied to an incinerator for incinerating sludge,
A sludge incineration system of the first aspect.

　It is necessary for the process to bleed a part of the circulating gas, but its treatment (specifically, the removal of odor and tar) has traditionally been difficult. In this embodiment, the dehumidified extraction gas is heat-exchanged with the high-temperature supply gas to obtain high-temperature extraction gas, thereby suppressing adhesion and solidification of tar to the extraction gas pipe. In addition, the sludge odor in the circulation path can be reduced by supplying the extraction gas to the incinerator.

(Fifth aspect)
an incinerator for incinerating sludge;
Equipped with a sludge input machine for inputting sludge into the incinerator,
The dried sludge separated by the separator is discharged to the sludge input machine,
The sludge feeder feeds the dried sludge and the first dehydrated sludge into the incinerator.
A sludge incineration system of the first aspect.

If the sludge that is put into the incinerator is only the first dehydrated sludge, the sludge combustion in the furnace will become unstable depending on the water content and amount of the first dehydrated sludge. In this aspect, since dried sludge is put into the incinerator in addition to the first dewatered sludge, the moisture content of the entire sludge to be incinerated is lowered, and sludge combustion is stabilized.

(Sixth aspect)
Furthermore, the second dehydrated sludge is put into the incinerator,
A sludge incineration system of the fifth aspect.

If the first dehydrated sludge and dried sludge are fed into the incinerator from a single feeding line, there is a risk of triggering a dust explosion inside the furnace. In this aspect, since the second dehydrated sludge is additionally put into the incinerator, dust explosion is suppressed.

(Seventh aspect)
Equipped with an incinerator to incinerate sludge,
Part of the preheated air passes through the circulating gas heater and is supplied to the incinerator, and the remaining part is supplied to the incinerator without passing through the circulating gas heater.
A sludge incineration system of the first aspect.

　The flow rate of the circulating gas flowing through the circulation path fluctuates depending on the operation status of the incinerator and the sludge incineration equipment including this. When the flow rate of the circulating gas is small, the circulating gas heater enters a so-called dry-heating state if the preheated air continues to flow quantitatively through the flow path, which may cause wear and damage. In this embodiment, the rest of the preheated air does not flow into the circulating gas heater, so that the circulating gas heater is less likely to run dry.

(Eighth aspect)
The temperature of the circulating gas supplied to the dryer is measured to obtain the measured temperature, the target temperature of the circulating gas supplied to the dryer is calculated based on the measured temperature, and the temperature of the circulating gas is the target Having a control device that controls to increase or decrease the flow rate of the air supplied from the outside so as to approach the temperature,
A sludge incineration system of the first aspect.

If the control device of this aspect is provided, the temperature of the circulating gas supplied to the dryer can be kept within a predetermined temperature, various facilities are less likely to be damaged or worn out early, and the running cost can be kept low. .

(Ninth aspect)
not introducing dried sludge into the dryer;
A sludge incineration system of the second aspect.

When drying the first dehydrated sludge, if it is a conventional dryer, it may be difficult to dry depending on the organic content concentration and water content, or it may take a long time to dry. It was mixed with sludge and dried as a mixture. On the other hand, in the dryer of the second aspect, even if the dried sludge is not mixed with the first dehydrated sludge, drying and pulverization can be easily achieved by introducing the first dewatered sludge alone into the dryer. The inventors are aware of this. Although the mechanism is not clear, it is probably due to the high-temperature circulating gas continuously colliding with the first dehydrated sludge, which is the object to be treated, at high speed.

(Tenth aspect)
In the sludge incineration method for incinerating sludge,
a circulation step in which the circulation gas flows through the circulation path;
A drying step of drying the first dehydrated sludge with the heat of the circulating gas to obtain dry sludge in a dryer;
A separation step of separating dry sludge and circulating gas in a separator;
A preheated air acquisition step of exchanging heat of air supplied from the outside with high-temperature exhaust gas generated by incinerating sludge in a circulating gas heater to obtain preheated air;
a high-temperature circulating gas obtaining step of heat-exchanging the circulating gas with the preheated air to heat it into a high-temperature circulating gas,
The circulating gas is discharged from the dryer together with the dried sludge, passes through the separator, reaches the circulating gas heater, is heated, and is supplied to the dryer again for circulation,
In the drying step, the first dewatered sludge is dried and pulverized into powdery dried sludge.
A sludge incineration method characterized by:

The same effects as in the first aspect can be expected.

According to the present invention, a sludge incineration system and a sludge incineration method that are unlikely to cause clogging or erosion of the flow path of the heat exchanger.

It is a figure showing one embodiment of the present invention. It is a figure showing the detail of a dryer. It is a figure showing one embodiment of the present invention. It is a figure showing one embodiment of the present invention.

<First Embodiment>
Next, a mode for carrying out the invention will be described. Note that this embodiment is an example of the present invention. The scope of the present invention is not limited to the scope of this embodiment.

The sludge incineration system of this embodiment includes a circulating gas flowing through the circulating paths (G1, G2, G3, G4, G5), a dryer 100 that dries the first dehydrated sludge 5 with the heat of the circulating gas to obtain dried sludge, A separator 10 for separating dry sludge and circulating gas, an air preheater 40 for exchanging heat with high-temperature exhaust gas generated by incinerating the sludge to preheat the air supplied from the outside, and circulating gas. , and a circulating gas heater 30 that exchanges heat with the preheated air to heat it into a high-temperature circulating gas, and the circulating gas is discharged from the dryer 100 together with dried sludge and passes through the separator 10. Then, the circulating gas heater 30 reaches the circulating gas heater 30 to be heated, and is supplied again to the dryer 100 for circulation. It is characterized by being made into sludge. One embodiment of the present invention will be described below with reference to FIG.

Each of the dampers V1 to V7 shown below has an opening/closing function that increases or decreases the flow rate of gas or air flowing through the pipes in which they are installed.

The first dewatered sludge 5 brought in from outside the system is fed into a fixed feeder 80, cut out in an appropriate amount, flows through the sludge pipe 6, is introduced into the sludge feeder 19, and is fed into the incinerator 20. Alternatively, the first dewatered sludge may be introduced directly into the sludge input device 19 (or the incinerator 20) without providing the sludge pipe 6 in particular. The quantitative feeder 80 can be exemplified by having two discharge parts, the first discharge part being connected to the sludge pipe 6 extending to the sludge input machine 19, and the second discharge part being a hopper. It is connected to the sludge pipe 7 extending to 90 . The first dehydrated sludge 5 is introduced from a constant feeder 80 into the incinerator 20 and the dryer 100 respectively. Although the first dewatered sludge 5 is not particularly limited, it is made by dehydrating a mixture of raw sludge and surplus sludge generated in a sewage treatment plant, and has a water content of 40 to 85%.

Although details will be described later, the sludge pipe 6 is provided with a flow sensor F1 that measures the flow rate of the first dehydrated sludge flowing in the sludge pipe 6, and the arithmetic device 110 receives the data of the measured value of the flow sensor F1. should be constructed.

The sludge feeder 19 is a device that feeds the sludge introduced by the sludge feeder 19 into the sludge feeder 21 of the incinerator 20. For example, the sludge is conveyed to the sludge feeder 21 by gravity, a belt conveyor, a constant feeder, or the like. It is something to do. Examples of the sludge to be conveyed include the first dehydrated sludge 5 and dried sludge.

(Incinerator)
The sludge conveyed by the sludge loading machine 19 is loaded into the incinerator 20 from the sludge loading section 21 . The incinerator 20 is equipment for incinerating the sludge that has been introduced. The incinerator 20 is not particularly limited, but examples thereof include a fluidized bed incinerator, a circulating fluidized bed incinerator, a stoker furnace, etc., and a supercharged fluidized bed incinerator is particularly preferable. In a supercharged fluidized bed incinerator, for example, sludge is supplied to a pressurized fluidized bed furnace and combusted, and the combustion exhaust gas discharged from the fluidized bed incinerator rotates a supercharger to generate compressed air. Combustion is promoted by supplying compressed air to the fluidized bed incinerator. In addition, the fluidized bed incinerator is a combustion furnace in which solid particles such as fluidized sand having a predetermined particle size are filled in the lower part of the furnace as a fluidizing medium. While maintaining the state, the sludge fed from the sludge feeding section 21 and the auxiliary fuel supplied as necessary are burned. At the bottom of the side wall, an auxiliary fuel combustion device (not shown) is arranged to heat the fluidized sand with a particle size of about 400 to 600 μm filled inside the fluidized bed incinerator, and in the vicinity of the upper side of the auxiliary fuel combustion device. is provided with a starting burner (not shown) for heating the fluidized sand at the time of starting, and a sludge input section 21 is provided above the starting burner. An air supply pipe 22 is installed below the fluidized bed incinerator to supply preheated air that provides oxygen necessary for combustion and kinetic energy for maintaining the fluidized state of the fluidized bed. As the air supply pipe 22, a distribution pipe in which a plurality of pipes having a plurality of openings are arranged, a distribution plate in which a plurality of openings are provided in a plate-like iron plate, or the like can be used. Furthermore, high-temperature extraction gas that has passed through a extraction gas heater 70, which will be described later, may be supplied from the air supply pipe 22 into the furnace. In this case, the high temperature bleed gas is supplied into the furnace through, for example, a bleed gas pipe G8 connecting the bleed gas heater 70 and the air supply pipe 22 . In addition, incineration exhaust gas means combustion gas generated when sludge is burned, or gas in which combustion gas and water vapor are mixed.

(Air preheater)
The incinerated exhaust gas generated in the incinerator 20 is discharged from the incinerator 20 at 800 to 900° C., flows through the incinerated exhaust gas pipe 39 connecting the exhaust gas discharge part of the incinerator 20 and the air preheater 40, and flows to the air preheater 40. influx. The air preheater 40 has a channel through which incinerated waste gas flows and a channel through which air supplied from the outside flows, and heat is exchanged indirectly between the two channels. The method of heat exchange used in the air preheater 40 is not particularly limited, but a tube type is preferable, and for example, a double tube type, a shell and tube type, or a spiral type can be used. The air supplied from the outside is supplied from the outside air under the room temperature or the outside temperature by the blower B2, and the air that connects the blower B2 and the base end of the flow path in the air preheater 40 through which the air supplied from the outside flows. It flows into the air preheater 40 through the pipe A1. The air pipe A1 can be provided with a damper V2 for adjusting the amount of air supplied. The air supplied from the outside is preheated by the air preheater 40, flows out from the air preheater 40 as preheated air of 80 to 700° C., and flows through the 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 combustion exhaust gas discharged from the air preheater 40 at 550 to 700° C. flows through the combustion exhaust gas pipe 49 connecting the white smoke prevention preheater 50 and the air preheater 40 and flows into the white smoke prevention preheater 50 . The white smoke prevention preheater 50 is for preventing the condensation and visualization of water vapor contained in the incineration exhaust gas, which occurs in the process of the incineration exhaust gas discharged from the chimney of the incineration facility diffusing in the atmosphere. The white-smoke prevention preheater 50 has a passage through which the supply gas, which is the air supplied from the outside to the white-smoke prevention preheater 50, flows, and a passage through which the combustion exhaust gas flows, and heat is exchanged indirectly between the two passages. is a type of heat exchanger in which The method of heat exchange used in the air preheater 40 is not particularly limited, but a tube type is preferable, and for example, a double tube type, a shell and tube type, or a spiral type can be used. The air supply gas is supplied to the white smoke prevention fan B3 and the white smoke prevention preheater by a fan (also referred to as "white smoke prevention fan B3") that sends outside air under room temperature or outside temperature to the white smoke prevention preheater 50 (also referred to as "white smoke prevention fan B3"). It flows through the air pipe A7 connecting the base end of the flow path through which the air supply gas flows in the device 50 and flows into the white smoke prevention preheater 50 . The supplied air gas passes through the white smoke prevention preheater 50 and exchanges heat with the incineration exhaust gas to obtain heat to become a high temperature supply gas of 200 to 400° C., and flows out of the white smoke prevention preheater 50 . The high temperature supply gas flows through the air pipe A8 that connects the white smoke prevention preheater 50 and the bleed gas heater 70 and flows into the bleed gas heater 70 .

On the other hand, the incinerated exhaust gas, which has passed through the white smoke prevention preheater 50 and has been reduced in temperature (cooled) to 200 to 600° C., flows through the incinerated exhaust gas pipe 59 and is sent to the incinerated exhaust gas treatment equipment 120 .

(Bleeding gas heater)
The high-temperature supply gas that has passed through the white smoke prevention preheater 50 flows through the air pipe A8 that connects the bleed gas heater 70 and the white smoke prevention preheater 50 , and flows into the bleed gas heater 70 . The bleed gas heater 70 heat-exchanges the bleed gas bled from the circulation path with the high temperature supply gas to obtain the high temperature bleed gas. A damper V6 can be provided in the air line A8 for adjusting the flow rate of the high temperature charge gas flowing to the bleed gas heater 70. As shown in FIG. The bleed gas heater 70 has a channel through which the high-temperature supply gas flows and a channel through which the bleed gas flows, and heat is exchanged indirectly between the two channels. The bleed gas is a part of the circulating gas, which is bleed from the circulation path.

　The circulation gas flowing through the circulation path contains tar and odor, and for the purpose of removing these, it is advisable to bleed some of the circulation gas. Since the extracted gas is led to the incinerator 20 and incinerated, the moisture-reduced gas (that is, dehumidified extracted gas) is more suitable for incineration. Further, since it is preferable that the extraction gas is heated by exchanging heat with the high-temperature supply gas in the extraction gas heater 70, the extraction gas is extracted from the section from the separator 10 to the circulation gas heater 30 in the circulation path. Good stuff. If it is the circulating gas in the section, the dry sludge has been removed and the temperature is relatively low, so there is an advantage that a suitable bleed gas can be bleed.

The bleed gas extracted from the circulation path flows through the bleed gas pipes G6 and G7 that connect the bleed gas heater 70 and the circulation path, and flows into the bleed gas heater 70 . Since the bleed gas flowing into the bleed gas heater 70 should be dehumidified, a condenser 60 for dehumidifying the bleed gas may be interposed, for example, between the bleed gas pipes G6 and G7.

The high temperature extraction gas preferably flows out from the extraction gas heater 70 at a temperature of 80° C. or higher, more preferably 120 to 210° C., flows through the extraction gas pipe G8 extending from the extraction gas heater 70 to the incinerator 20, and flows into the incinerator. 20 and incinerated along with the sludge as air fuel. If the temperature of the bleed gas flowing out of the bleed gas heater 70 is less than 350° C., the tar contained in the bleed gas may liquefy and adhere to the piping, causing clogging. Therefore, the liquefaction of tar is suppressed by raising the temperature of the extraction gas. In addition, the extracted gas contains tar and odor, which adversely affects various facilities, but incineration can eliminate these adverse effects as much as possible.

The high-temperature supply gas flows through the flow path through which the high-temperature supply gas flows, is deprived of heat by the extraction gas, and flows out from the extraction gas heater 70 at 150 to 500° C., connecting the extraction gas heater 70 and the chimney 130. It flows through the air pipe A9 and is led to the chimney 130.

The bleed gas heater 70 becomes hot when the high-temperature supply gas continues to flow when the amount of bleed gas inflow is small, resulting in a so-called dry-heating state. In order to avoid this, it is possible to provide a bypass air pipe A10 for releasing the hot supply gas from the air pipe A8 to the air pipe A9 and a damper V7 installed in the bypass air pipe A10. The bypass air pipe A10 is preferably provided at a position upstream of the damper V6 in the air pipe A8. By providing the bypass air pipe A10, the amount of supply gas flowing to the white smoke prevention preheater 50 is made sufficient, while part of the high temperature supply gas is released to the air pipe A9, and the remaining part is released to the extraction gas heater 70. can be supplied to By doing so, it becomes possible to adjust the flow rate of the high-temperature supply gas flowing into the extraction gas heater 70 in accordance with the flow rate of the extraction gas flowing into the extraction gas heater 70 .

Bleeding means extracting part of the circulation gas flowing through the circulation path.

(circulating gas heater)
The preheated air obtained by exchanging heat from the incineration exhaust gas in the air preheater 40 flows out of the air preheater 40, and at 200 to 700° C., the air connecting the circulating gas heater 30 and the air preheater 40. It flows through the pipes A2 and A3 and flows into the circulating gas heater 30 . The circulating gas heater 30 has a channel through which the circulating gas flows and a channel through which the preheated air flows, and heat is exchanged indirectly between the two channels. The method of heat exchange used in the circulating gas heater 30 is not particularly limited, but a tube type is preferable. And tube heat exchangers are preferred. When a shell-and-tube heat exchanger is used, it is preferable to flow the circulating gas through the heat transfer tubes where dust is less likely to accumulate because the circulating gas contains dust, and to flow the preheated air through the shell. In addition, the air pipe A2 and the air pipe A3 are connected and integrated, and are configured so that the preheated air flows continuously between the two pipes.

A damper V1 should be installed in the air pipes A2 and A3. By opening and closing the damper V1, the flow rate of the preheated air can be increased or decreased, the amount of 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.

Also, an air pipe A4 can be provided that is branched from the air pipes A2 and A3 to flow preheated air to the air supply pipe 22 of the incinerator 20. It is preferable that the branch point be upstream of the installation position of the damper V1 in the air pipes A2 and A3. A damper V3 capable of adjusting the flow rate of the preheated air can be provided in the air pipe A4. With this configuration, part of the preheated air passes through the circulating gas heater and is supplied to the incinerator, and the remaining part is supplied to the incinerator without passing through the circulating gas heater. can be

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 if the air supply pipe 22 is provided) and the circulating gas heater 30, and flows into the incinerator 20. .

The circulating gas heater 30 of the present embodiment has a channel through which preheated air, which is clean air, flows and a channel through which circulating gas flows, and heat is exchanged between these channels. Since the preheated air is preheated air supplied from the outside of the sludge incineration system, the preheated air does not contain dust or tar and is clean. Therefore, since dust and tar do not flow into the flow path through which the preheated air flows, clogging or erosion of the flow path due to dust or tar is unlikely to occur.

(Circulation path)
The circulation paths (G1, G2, G3, G4, G5) are paths through which the circulation gas flows. and a channel G3 to which the circulating gas heater 30 and the dryer 100 are connected. A blower B1 can be provided in the circulation path so that the circulation gas flows. The blower B1 is preferably installed in a channel where the circulating gas is not at a high temperature and contains as little dried sludge as possible. is preferred. In addition, the flow path G5, the flow path G1, and the flow path G2 are connected so that the circulating gas flows.

　The flow rate of the circulating gas is partially reduced by bleeding, and it is preferable to introduce outside air to make up for the decrease. For example, an outside air introduction pipe G9 is connected upstream of the installation position of the blower B1 in the flow path (G5, G1, G2) so that the outside air flows through the outside air introduction pipe G9 and is introduced into the circulation path. do.

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

A damper V5 can be provided in the extraction gas pipe G6. By opening and closing the damper V5, it is possible to adjust the flow rate of the extraction gas in accordance with the flow rate of the high-temperature supply gas flowing through the extraction gas heater 70, which is preferable.

(circulating gas)
A specific flow of the circulating gas will be described below. In addition, the temperature of the circulation gas shown below is an example. Outside air introduced from the outside air introduction pipe G9 flows through the flow paths (G5, G1, G2) as circulating gas, passes through the circulating gas heater 30, obtains heat, and heats the circulating gas heater at 300 to 500 ° C. outflow from 30. The outflowing circulating gas (high-temperature circulating gas) flows through the flow path G3 and flows into the dryer 100 .

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

The circulating gas that has flowed into the separator 10 has dried sludge separated by the separator 10, and the residue flows out at 100 to 400°C, reaches the flow path (G5, G1, G2) again, and circulates.

The flow rate of the circulating gas can be adjusted by the blower B1 installed 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 brings the first dehydrated sludge fed from the hopper 90 into contact with the high-temperature circulating gas flowing from the circulation path, and dries and pulverizes the first dehydrated sludge into powdery dried sludge.

The dryer 100 includes: (1) a spray dryer, a flash dryer, a fluidized bed dryer, a rotary dryer, etc., in which the first dehydrated sludge is dispersed and dried in a high-temperature circulating gas; (2) The first dewatered sludge is transferred while still standing, such as a ventilation band dryer, tunnel dryer (parallel flow band dryer), jet flow dryer, etc., and the first dewatered sludge is transferred during the transfer process. (3) mechanically stirring the first dehydrated sludge, such as a stirring dryer, and bringing the first dehydrated sludge into contact with the high temperature circulation gas; A dried form can be exemplified.

Although there are various types of the above-mentioned flash dryers, it is possible to adopt a flash dryer without a crusher, in which the first dewatered sludge is put in without being crushed.

A flash dryer is shown as the dryer 100 in FIGS. This flash dryer includes a pipe 100B extending in an annular shape, a sludge introduction section 100E into which the first dehydrated sludge is introduced into the pipe 100B, and a gas supply section into which high-temperature circulation gas is supplied into the pipe 100B. 100A and a gas discharge section 100F for discharging circulating gas containing dried sludge from the pipe 100B, and the high-temperature circulating gas supplied from the gas supply section 100A circulates at high speed in the pipe 100B, It is configured to collide with the first dewatered sludge introduced from the sludge introduction section 100E. The pipe 100B includes a pipe portion 100Ba connected to the gas supply portion 100A and extending horizontally, a pipe portion 100Bb extending while curving upward from the pipe portion 100Ba, and a direction (pipe It is composed of a pipe portion 100Bc that curves and extends in a direction parallel to the portion 100Ba, and a pipe portion 100Bd that curves and extends downward from the pipe portion 100Bc. Further, the pipe portion 100Bd is provided with a tip portion 100C which is joined to the tip 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. Also, a sludge introduction section 100E is provided in the pipe 100B, particularly the pipe section 100Ba, and a gas discharge section 100F is provided in the pipe 100B.

The high-temperature circulating gas is supplied to the gas supply section 100A through the flow path G3. The first dehydrated sludge introduced into the pipe 100B from the sludge introduction portion 100E through the sludge pipe 4 is introduced into the high-temperature circulating gas circulating in the pipe portion 100Ba, continuously collides with the high-temperature circulating gas, and enters the pipe 100B. It is blown away inside, dispersed and dried to become powdery dry sludge. At this time, the large sludge particles of the first dehydrated sludge collide with the high-temperature, high-speed circulating gas, breaking into a plurality of small sludge particles, and the water contained therein rapidly evaporates.

The powdery sludge particles that have been dispersed and dried to a particle size below a certain level are discharged from the gas discharge part 100F as dry sludge to the outside of the flash dryer while being included in the flow of the circulating gas. On the other hand, relatively large sludge grains that are not sufficiently dispersed and dried are not discharged from the gas discharge section 100F, and are repeatedly circulated in the pipe 100B until sufficiently dispersed and dried. Therefore, the flash dryer mainly discharges well-dispersed and dried powdery and dried sludge. Specifically, the high-temperature circulating gas is supplied from the gas supply unit 100A to the pipe 100B, and circulates with the sludge particles through the pipe section 100Ba, the pipe section 100Bb, the pipe section 100Bc, the pipe section 100Bd, and the pipe section 100Ba. It is discharged out of the dryer 100 from the gas discharge part 100F. On the other hand, the high-temperature circulating gas that has not been exhausted joins and mixes with the high-temperature circulating gas newly sent from the gas supply section 100A, and flows through the pipe section 100Ba, the pipe section 100Bb, the pipe section 100Bc, and the pipe section 100Bd. is exhausted to the outside of the dryer 100 from the gas exhaust portion 100F. As described above, part of the high-temperature circulating gas is discharged from the gas discharge section 100F, and the remaining high-temperature circulating gas circulates through the pipe 100B. In this way, the first dehydrated sludge newly introduced and the first dehydrated sludge circulating in the pipe 100B are mixed in the pipe, dried and pulverized through circulation.

In the operation of the flash dryer, the flow velocity of the high-temperature circulating gas flowing through the gas supply part 100A of the flash dryer is 20 m/s or more and 60 m/s or less, and the flow velocity in the pipe 100B is 15 m/s or more and 45 m/s or less. It is preferable to If the flow velocity of the gas supply part 100A and the pipe 100B is lower than the above value, the sludge particles are difficult to circulate in the flash dryer, which may hinder the drying process and discharge to the outside of the circulator. Moreover, the flow velocity in the pipe 100B is more preferably 15 m/s or more so that the sludge particles can circulate smoothly.

In particular, it is preferable to make the flow velocity of the gas supply section 100A faster than the flow velocity of the pipe 100B. By providing a speed difference, the newly supplied high-temperature circulation gas continuously collides with the circulating sludge particles, thereby promoting the dispersion of the sludge particles.

Also, the temperature of the high-temperature circulating gas circulating in the dryer 100 is preferably 300 to 500°C, more preferably 350 to 450°C, and even more preferably 400°C. If the temperature of the hot circulating gas is below this range, it will take a long time to dry. On the other hand, there is little merit in setting the temperature higher than this range, and while a lot of energy is consumed to raise the temperature, there is a demerit that the cost-effectiveness of facility management is reduced.

In addition to the flash dryer shown above, as the capacity of auxiliary equipment increases, periodic maintenance and replacement of the crusher are required, but even if a flash dryer with a crusher is installed , the same effect as the flash dryer can be obtained.

The circulating gas containing the dried sludge that has flowed out of the dryer 100 is deprived of heat by the drying of the first dehydrated sludge in the dryer 100 and reaches 100 to 400°C. The dried sludge generated in the dryer 100 is transported to the separator 10. If transported to the separator 10 together with the circulating gas, for example, it is preferable that no separate equipment is required for transport. The circulating gas containing dried sludge flows through a flow path G4 that connects the gas discharge portion 100F of the dryer 100 and the circulating gas inlet portion of the separator 10 and is supplied to the separator 10 .

The dry sludge discharged from the dryer 100 has a water content of 1 to 40%.

(Separator)
The separator 10 gas-solid separates the circulating gas containing dried sludge supplied from the flow path G4, removes the dried sludge, and discharges the residue to the flow path G5. The separator 10 includes a sludge supply section that receives supply of circulation gas containing dried sludge, a sludge discharge section 11 that discharges the separated dry sludge, and a residue of the circulation gas from which the dried sludge has been separated. The separated dry sludge is discharged from the separator 10 to, for example, a sludge input machine 19, which is provided with a gas discharge section to be discharged to the path G5. The separated dried sludge may fall naturally from the sludge discharge unit 11 and be supplied to the sludge input device 19, or a sludge pipe 3 connecting the sludge discharge unit 11 and the sludge input device 19 is provided, and the sludge pipe 3 to the sludge input machine 19.

Examples of the separator 10 include a gravity sedimentation chamber that collects dust by gravity, a mist separator that collects dust by inertia, a cyclone that collects dust by centrifugal force, a venturi scrubber that collects dust by washing, and a filter cloth that collects dust. a bag filter that performs dust collection, a moving particle layer air filter that collects dust with a packed layer, an electric dust collector that collects dust with electricity, and the like.

The separator 10 can be provided directly above the sludge input device 19, and the separated dry sludge can be discharged from the sludge discharge part 11 of the separator 10 to the sludge input device 19. Since the dried sludge is light in weight and accompanied by a strong sludge odor, it scatters when the transport route is long, and the sludge odor wafts around. Therefore, if the dried sludge is discharged from the sludge discharge part of the separator to the sludge input machine directly below, it is quickly input to the incinerator, so that the scattering of the dried sludge and the emission of its odor can be suppressed as much as possible. .

(First dehydrated sludge)
The first dewatered sludge 5 is temporarily stored in the quantitative feeder 80, and an appropriate amount of it flows through the sludge pipe 7 connecting the hopper 90 and the quantitative feeder 80, flows into the hopper 90, and is stored. The sludge stored in the hopper 90 flows through the sludge pipe 4 connecting the sludge introduction part 100E of the dryer 100 and the hopper 90 and is introduced into the dryer 100 .

The hopper 90 may receive the dried sludge separated by the separator 10 in addition to receiving the first dehydrated sludge. The dried sludge separated by the separator 10 may be manually transported to the hopper 90 and put into it, or a sludge pipe 9 connecting the hopper 90 and the separator 10 is provided, and the sludge pipe 9 is flown into the hopper. You can put it in 90. Thereby, the first dewatered sludge and the dried sludge are mixed within the hopper 90 . The first dehydrated sludge may be difficult to dry or may take a long time to dry depending on the concentration of organic matter and water content. By introducing the mixture of the first dewatered sludge and the dried sludge into the dryer 100, drying of the mixture is accelerated and pulverization is facilitated.

(control)
In order to control the operation of the sludge incineration system of this embodiment, a control device using the arithmetic device 110 can be provided. Temperature sensors and flow rate sensors are installed in various places in the sludge incineration system to perform this control. Details are given below.

As for the temperature sensors, as an example, a temperature sensor T1 that measures the temperature of the incinerated exhaust gas flowing through the incinerated exhaust gas pipe 39, a temperature sensor T2 that measures the temperature inside the incinerator 20, and a 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.

As for the flow rate sensor, as an example, a flow rate sensor F1 for measuring the flow rate of the first dehydrated sludge flowing through the sludge pipe 6 described later, a flow rate sensor F2 for measuring the flow rate of the first dehydrated sludge flowing through the sludge pipe 7, the flow path G1, A flow sensor F3 may each be provided to measure the flow rate of the circulating gas through G2.

The temperature data measured by the temperature sensors T1 to T5 and the flow rate data measured by the flow sensors F1 to F3 are transmitted to the computing device 110 by wire or wirelessly. The computing device 110 computes the output values of the openings of the dampers V1 to V7 by using a computational expression provided in advance based on the received input values of the measured temperature data and the measured flow rate data. Arithmetic device 110 transmits the output values to dampers V1 to V7. The dampers V1 to V7 operate their respective actuators, and open or close the valves to change the flow rate so that the degree of opening up to that point becomes the degree of opening corresponding to the received output value. The arithmetic expression is not particularly limited, but is constructed from past measured temperature data, measured flow data, and opening data, for example, by least square method control, PI control, PDI control, neural network control, and manual input method. can do.

As a control device, for example, the temperature of the circulation gas supplied to the dryer 100 is measured to obtain the measured temperature, the target temperature of the circulation gas supplied to the dryer 100 is calculated based on the measured temperature, and the For example, the flow rate of the air supplied from the outside is controlled so that the temperature of the circulating gas approaches the target temperature. Here, the control to increase or decrease the flow rate of the air supplied from the outside means, for example, when the sludge incineration system is operating with the damper V2 at a specific opening (actual opening), the measured temperature is As an input value, the target opening of the damper V2 is obtained as an output value by inputting it into a pre-provided arithmetic expression, and by bringing the actual opening of the damper V2 close to the target opening obtained as the output value, it is supplied from the outside. It refers to control that increases or decreases the flow rate of the air that is applied. This control increases or decreases the flow rate of the preheated air flowing into the circulating gas heater 30 and increases or decreases the temperature of the circulating gas that undergoes heat exchange.

Further, as another control device, for example, the flow rate of the circulating gas flowing through the flow path G2 is measured to obtain the measured flow rate, the target flow rate of the circulating gas flowing through the flow path G2 is calculated based on the measured flow rate, and the circulation gas flow rate is calculated. For example, the flow rate of the circulating gas is controlled to increase or decrease so that the flow rate of the gas approaches the target flow rate. Here, the control to increase or decrease the flow rate of the circulating gas is, for example, when the sludge incineration system is operating with the damper V5 at a specific opening (actual opening), the measured flow rate is used as an input value, and The target opening of the damper V5 is obtained as an output value by inputting it into the provided arithmetic expression, and by bringing the actual opening of the damper V5 closer to the target opening obtained as the output value, the flow rate of the circulating gas is increased or decreased. That's what I mean. This control increases or decreases the flow rate of the circulating gas passing through the circulating gas heater 30 and increases or decreases the temperature of the circulating gas flowing into the dryer 100 .

Furthermore, based on the data of the measured temperature of each of the temperature sensors T1 to T5 and the data of the measured flow rate of each of the flow sensors F1 to F3, the target introduction amount of the first dehydrated sludge to the dryer 100, and the first to the incinerator 20 1 A device can be used in which a target input amount of dehydrated sludge is calculated, and the discharge amount of dewatered sludge in the constant feeder 80 is controlled so as to achieve the target introduction amount and the target input amount.

<Second embodiment>
Although the embodiment of the present invention has been described above, as shown in FIG. A sludge incineration system with the added feature of not introducing sludge into the dryer is also a desirable embodiment. FIG. 3 is a system diagram without the sludge pipe 9 shown in FIG. In conventional dryers, dried sludge is introduced together with the first dewatered sludge, but in the dryer characterized by this embodiment, high-temperature circulation gas circulates in the dryer and the dried sludge is not actively introduced. Also, the first dewatered sludge is easily dried. Therefore, there is no need to provide a pipe or the like for guiding the dried sludge to the dryer, and there is an advantage that the form of the entire sludge incineration system can be made compact.

<Third Embodiment>
The following third embodiment is also preferable as shown in FIG. Specifically, the sludge incineration system of the first aspect further includes an incinerator 20 for incinerating sludge, and in addition to the first dewatered sludge, the second dehydrated sludge is introduced into the incinerator 20. Sludge incineration System.

The second dewatered sludge 1 brought in from outside the system is put into the sludge hopper 140 . A sludge discharger is provided in the sludge hopper 140 , and the sludge discharger and the sludge feeder 19 are connected by a sludge pipe 2 . The second dewatered sludge 1 discharged from the sludge discharging section flows through the sludge pipe 2 into the sludge input machine 19 .

In this embodiment, examples of the sludge conveyed by the sludge feeder 19 include the first dehydrated sludge 5, the second dehydrated sludge, dried sludge, and the like. Both the second dehydrated sludge 1 and the first dehydrated sludge 5 are dehydrated sludge, and are put into the incinerator 20 as separate bodies. The whole amount of the second dehydrated sludge 1 is put into the incinerator 20 . In the incineration of only the first dehydrated sludge 5, self-combustion by the incinerator 20 may become unstable depending on the properties, organic content concentration, and water content of the first dehydrated sludge 5, and in addition to the dried sludge, the second dehydrated sludge By introducing , the incinerator 20 will continue to burn stably.

Based on the first to third embodiments described above, the following sludge incineration system is also a preferred form. For example, the white smoke prevention preheater 50 heat-exchanges the air supply gas supplied from the white smoke prevention fan B3 with the incineration exhaust gas that has passed through the air preheater 40 to produce a high temperature supply gas, and the circulating gas A bleed gas heater 70 is provided for heat-exchanging the bleed gas with the high-temperature supply gas to make the high-temperature bleed gas, and the bleed gas is connected to the separator 10 and the circulating gas heater 30. A sludge incineration system can be provided in which the high-temperature extracted gas is dehumidified by extraction from the circulation paths (G5, G1, G2) and is supplied to an incinerator 20 for incinerating sludge. This sludge incineration system is preferable because it suppresses adhesion and solidification of tar to the extraction gas pipe. In addition, since the extraction gas is supplied to the incinerator 20, the sludge odor in the circulation path can be reduced.

Moreover, as a sludge incineration method performed using the embodiment shown above, the following can be illustrated.
The sludge incineration method for incinerating sludge is
(1) a circulation step in which the circulation gas flows through the circulation paths (G1, G2, G3, G4, G5);
(2) a drying step of drying the first dehydrated sludge 5 with the heat of the circulating gas to obtain dry sludge in the dryer 100;
(3) a separation step of separating dry sludge and circulating gas in a separator 10;
(4) In the circulating gas heater 30, the air supplied from the outside is heat-exchanged with the high-temperature exhaust gas generated by incinerating the sludge to obtain preheated air;
(5) obtaining a high-temperature circulating gas by exchanging heat with the preheated air to heat the circulating gas to obtain a high-temperature circulating gas;
The circulating gas is discharged from the dryer 100 together with dried sludge, passes through the separator 10, reaches the circulating gas heater 30, is heated, and is supplied to the dryer 100 again for circulation. and the drying step is characterized in that the first dehydrated sludge is dried and pulverized into powdery dried sludge.

(others)
Granular dry sludge is difficult to define strictly, but for example, dry sludge with a size that can be smoothly flowed with the flow of air when air is flowed through a pipe at a flow rate of 20 m / sec. say.
Regarding the main lines shown in the figure, the pipes through which circulating gas and extraction gas flow are solid lines, the pipes through which combustion exhaust gas flows are thick solid lines, and the pipes through which the first dehydrated sludge, dried sludge, and second dehydrated sludge flow are one point. Chain lines indicate piping through which externally supplied air, preheated air, supply gas, and high-temperature supply gas flow, and dashed lines indicate the transmission/reception network between the temperature sensor, flow rate sensor, damper, and the arithmetic unit.

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

1 Second dehydrated sludge 5 First dehydrated sludge 10 Separator 30 Circulating gas heater 40 Air preheater 100 Dryer G1 Circulation path G2 Circulation path G3 Circulation path G4 Circulation path G5 Circulation path

Claims (10)

1. In a sludge incineration system that incinerates sludge,
   a circulating gas flowing through the circulating path;
   a dryer that dries the first dehydrated sludge with the heat of the circulating gas to obtain dried sludge;
   a separator for separating the dried sludge and the circulating gas;
   an air preheater that exchanges the heat of the air supplied from the outside with the high-temperature incineration exhaust gas generated by incinerating the sludge and converts it into preheated air;
   a circulating gas heater that heats the circulating gas by exchanging heat with the preheated air to produce a high-temperature circulating gas,
   The circulating gas is discharged from the dryer together with the dried sludge, passes through the separator, reaches the circulating gas heater, is heated, and is supplied to the dryer again for circulation,
   The dryer dries and pulverizes the first dewatered sludge into powdery dried sludge.
   A sludge incineration system characterized by:
2. The dryer is
   A pipe extending in an annular shape, a sludge introduction part into which the first dewatered sludge is introduced into the pipe, a gas supply part into which high temperature circulation gas is supplied into the pipe, and a circulation gas containing dried sludge is supplied to the pipe. a gas discharge part discharged from the pipe,
   The high-temperature circulating gas supplied from the gas supply unit circulates at high speed in the pipe and collides with the first dehydrated sludge introduced from the sludge introduction unit.
   The sludge incineration system according to claim 1.
3. Dried sludge generated in the dryer is transported to the separator together with the circulating gas,
   The sludge incineration system according to claim 1.
4. a white smoke prevention preheater that exchanges heat with the incineration exhaust gas that has passed through the air preheater to convert the air supply gas supplied from the white smoke prevention fan into high-temperature supply air;
   a bleed gas heater that heat-exchanges the bleed gas bled from the circulating gas with the high-temperature supply gas to produce a high-temperature bleed gas,
   The bleed gas is dehumidified by bleed from a circulation path connecting the separator and the circulating gas heater,
   The high temperature extraction gas is supplied to an incinerator for incinerating sludge,
   The sludge incineration system according to claim 1.
5. an incinerator for incinerating sludge;
   Equipped with a sludge input machine for inputting sludge into the incinerator,
   The dried sludge separated by the separator is discharged to the sludge input machine,
   The sludge feeder feeds the dried sludge and the first dehydrated sludge into the incinerator.
   The sludge incineration system according to claim 1.
6. Furthermore, the second dehydrated sludge is put into the incinerator,
   The sludge incineration system according to claim 5.
7. Equipped with an incinerator to incinerate sludge,
   Part of the preheated air passes through the circulating gas heater and is supplied to the incinerator, and the remaining part is supplied to the incinerator without passing through the circulating gas heater.
   The sludge incineration system according to claim 1.
8. The temperature of the circulating gas supplied to the dryer is measured to obtain the measured temperature, the target temperature of the circulating gas supplied to the dryer is calculated based on the measured temperature, and the temperature of the circulating gas is the target Having a control device that controls to increase or decrease the flow rate of the air supplied from the outside so as to approach the temperature,
   The sludge incineration system according to claim 1.
9. not introducing dried sludge into the dryer;
   The sludge incineration system according to claim 2.
10. In the sludge incineration method for incinerating sludge,
    a circulation step in which the circulation gas flows through the circulation path;
    A drying step of drying the first dehydrated sludge with the heat of the circulating gas to obtain dry sludge in a dryer;
    A separation step of separating dry sludge and circulating gas in a separator;
    A preheated air acquisition step of exchanging heat of air supplied from the outside with high-temperature exhaust gas generated by incinerating sludge in a circulating gas heater to obtain preheated air;
    a high-temperature circulating gas obtaining step of heat-exchanging the circulating gas with the preheated air to heat it into a high-temperature circulating gas,
    The circulating gas is discharged from the dryer together with the dried sludge, passes through the separator, reaches the circulating gas heater, is heated, and is supplied to the dryer again for circulation,
    In the drying step, the first dewatered sludge is dried and pulverized into powdery dried sludge.
    A sludge incineration method characterized by:

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