JP4267210B2 - Waste treatment system and operation method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a treatment system for waste such as human waste, sewage treatment facilities and various production factories, and in particular, a drying process and an incineration process, carbonization process or The present invention relates to a waste treatment system capable of operating a melting process efficiently and an operation method thereof.
[0002]
BACKGROUND OF THE INVENTION
Conventionally, when processing waste such as sludge and municipal waste that contain a large amount of water discharged from human waste, sewage treatment facilities and various production plants, this is subjected to a drying process in order to improve processing efficiency. After the removal, the incineration, carbonization or melting treatment is subsequently applied.
For example, when sludge is dried and incinerated, a dry incineration system S ′ as shown in FIG. 4 is used. The dehydrated sludge that has been dehydrated in advance is put into the dryer 1 ′ and dried. The dried sludge obtained here is put into the incinerator 2 'and incinerated.
[0003]
Thus, the dry incineration system S ′ comprises a drying process and an incineration process, and the heat of the incineration exhaust gas G2 generated in the incinerator 2 ′ is also effectively used. The dry incineration system S ′ shown in FIG. 4 is disclosed in Japanese Patent Application Laid-Open No. 11-82975 “Manure sludge treatment system” by the applicant of the present invention. The dry exhaust gas G1 discharged from ′ is indirectly heated by the incineration exhaust gas G2 discharged from the incinerator 2 ′, and the heated dry exhaust gas G1 is supplied again to the dryer 1 ′ for drying. It is reused as a heat source.
As described above, the incineration exhaust gas G2 and the dry exhaust gas G1 are not in direct contact with the dry incineration system S ′, so that the dioxins contained in the incineration exhaust gas G2 are not adsorbed on the dry sludge, and the dry sludge is reused as fertilizer. It is possible to do.
[0004]
By the way, when operating the dry incineration system S ′, if any trouble occurs in the dryer 1 ′, the dryer 1 ′ must be stopped and the incinerator 2 ′ must also be stopped.
This is because the supply of the dry exhaust gas G1 serving as a heat load in the heat exchanger 3 'is stopped, so that the incineration exhaust gas G2 is kept at a high temperature without being lowered in the heat exchanger 3'. This is because the ability of the exhaust gas treatment device 4 'to remove harmful substances such as dioxins is greatly reduced, and the heat exchanger 3' and the bag filter 42 'may be damaged. Here, the dry incineration system S ′ including the dryer 1 ′ and the incinerator 2 ′ has been described as an example. However, the same applies to a system including a carbonization furnace or a melting furnace instead of the drying furnace 2 ′. When some trouble occurred in the dryer 1 ', the dryer 1' had to be stopped and the carbonization furnace or melting furnace had to be stopped.
[0005]
[Technical problem to be solved]
The present invention has been made in view of such a background, and the dry exhaust gas discharged from the dryer is indirectly heated by the exhaust gas discharged from the incinerator, carbonization furnace or melting furnace and dried. New disposal that can be efficiently operated as a whole system without causing the incinerator, carbonization furnace or melting furnace to stop when the dryer is stopped, while being reused as the drying heat source of the dryer Development of material processing system and its operation method was a technical issue.
[0006]
[Means for Solving the Problems]
In other words, the waste treatment system according to claim 1 leads the dry exhaust gas discharged from the dryer for drying waste such as sludge and municipal waste to the heat exchanger and is discharged from the incinerator, carbonization furnace or melting furnace. The exhaust gas is separately guided to the heat exchanger, and the dry exhaust gas and the incineration exhaust gas etc. are directly contacted with each other without directly contacting them, and after raising the temperature of the dry exhaust gas, In a system that is recycled to the dryer and reused as a drying heat source,
In the circulation path of the dry exhaust gas, an open air introduction path that can be opened and closed is provided between an exhaust port in the dryer and an introduction port in the heat exchanger, and an air supply port in the dryer and an exhaust port in the heat exchanger; An exhaust path to the open air that can be opened and closed is provided between the two.
According to the present invention, it is possible to select either dry exhaust gas or outside air as a gas that becomes a heat load such as incineration exhaust gas in the heat exchanger.
[0007]
In addition to the above requirements, the dry incineration system according to claim 2 is provided between a pipe line connected to a dry exhaust gas introduction port in the heat exchanger and a pipe line connected to a discharge port in the heat exchanger. Is characterized by providing a feedback path that can be opened and closed.
According to the present invention, it is possible to mix the outside air that has just been taken into the system with the temperature increased by performing heat exchange with the incineration exhaust gas or the like.
[0008]
Furthermore, the operation method of the dry incineration system according to claim 3 is directed to the exhaust gas discharged from the dryer for drying waste such as sludge and municipal waste to the heat exchanger, and to the incinerator, carbonization furnace or melting furnace. The exhaust gas discharged from the gas is separately guided to the heat exchanger, and the dry exhaust gas and the incineration exhaust gas etc. are directly contacted with each other without bringing them into direct contact with each other. In the operation of a system that circulates dry exhaust gas into a dryer and reuses it as a drying heat source,
During steady operation, the outside air introduction path provided between the exhaust port of the dryer and the introduction port of the heat exchanger is closed, and further provided between the supply port of the dryer and the discharge port of the heat exchanger. The exhaust route to the outside air is closed, and the temperature-controlled dry exhaust gas is circulated and introduced into the dryer.
On the other hand, when the dryer is stopped, the air supply port and the exhaust port in the dryer are closed, and the outside air introduction path provided between the exhaust port in the dryer and the introduction port in the heat exchanger is opened. Open the exhaust path to the outside air provided between the air supply port in the dryer and the exhaust port in the heat exchanger, and let the outside air taken in from the outside air introduction path heated by incineration exhaust gas etc. in the heat exchanger It is characterized by exhausting to the outside.
According to the present invention, when the drying machine is stopped and the supply of the dry exhaust gas that becomes a heat load of the incineration exhaust gas or the like is stopped in the heat exchanger, the incineration exhaust gas etc. Can be supplied to the exhaust gas treatment device in a state where the temperature of the exhaust gas treatment device is lowered, processing within the treatment capacity of the exhaust gas treatment device becomes possible, and the operation of the incineration system can be continued.
[0009]
In addition to the requirement of claim 3, the operation method of the dry incineration system according to claim 4 is connected to a pipe line connected to a dry exhaust gas inlet in the heat exchanger and a discharge port in the heat exchanger. The outside air taken in from the outside air introduction route heated by the incineration exhaust gas etc. is mixed with the newly taken outside air by adjusting the opening of the feedback route provided between It consists of
According to the present invention, the outside air just taken into the system is mixed with the outside air in a state where the temperature is raised by performing heat exchange with the incineration exhaust gas or the like, so that the heat exchanger is not burdened. It is possible to operate in a state close to normal operation.
The above problems can be solved by using the configuration of the invention described in each of the claims as a means.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the waste disposal system of the present invention and the operation method thereof will be described with reference to a system for drying and incinerating sludge and the operation method thereof as an example. In this description, the configuration of the dry incineration system S will be described first, and then the operation method of this system will be described.
What is indicated by a symbol S in the figure is the dry incineration system of the present invention, which comprises a dryer 1, an incinerator 2, a heat exchanger 3 and an exhaust gas treatment device 4 as main components, which are connected by a pipe line. It is made up of. And after dehydrating the human waste, sludge discharged from sewage treatment facilities and various production factories as appropriate, the dried sludge is dried with the dryer 1 and further incinerated with the incinerator 2. is there.
In the present specification, the exhaust gas discharged from the dryer 1 is defined as a dry exhaust gas G1, and the exhaust gas discharged from the incinerator 2 is defined as an incineration exhaust gas G2.
Hereinafter, these constituent elements and gas paths connecting the constituent elements will be described.
[0011]
First, as the dryer 1, a known rotary drum dryer with a crushing and stirring blade is applied as an example. In this system, dewatered sludge obtained by dewatering sludge with a dehydrator (not shown) is appropriately dried. And is used to produce dry sludge.
The heat source for drying uses the incineration exhaust gas G2 of the hot air furnace 10 and the incinerator 2, and heat is exchanged between the dry exhaust gas G1 and the incineration exhaust gas G2 by the heat exchanger 3 to raise the temperature. The dry exhaust gas G1 is returned to the dryer 1 again.
[0012]
Specifically, the exhaust port 11 of the dryer 1 and the introduction port 31 of the heat exchanger 3 are connected by a pipe line, and further connected to the discharge port 32 of the heat exchanger 3 and the air supply port 12 of the dryer 1. The dry exhaust gas circulation path 5 starting from the exhaust port 11 and starting from the air supply port 12 is configured by connecting the hot stove 10 to the hot stove 10 by a pipe line.
Further, a branch path 50 connected to the incinerator 2 is provided between the discharge port 32 of the heat exchanger 3 and the air supply port 12 of the dryer 1 in the dry exhaust gas circulation path 5. 3, a part of the dried exhaust gas G 1 whose temperature is increased is introduced into the incinerator 2, burned and deodorized, and then supplied to the exhaust gas treatment device 4 through the incineration exhaust gas discharge path 6.
[0013]
Note that a dust collector 51 and an induction fan F5 are provided between the dryer 1 and the heat exchanger 3 in the dry exhaust gas circulation path 5, thereby collecting dust in the dry exhaust gas G1 and circulating the dry exhaust gas G1. Is intended.
[0014]
Next, the heat exchanger 3 will be described. This is a device for exchanging heat between the dry exhaust gas G1 and the incineration exhaust gas G2, and this heat exchange is performed indirectly without direct contact between them. For example, a configuration is adopted in which incineration exhaust gas G2 is flowed into the pipe, dry exhaust gas G1 is flowed out of the pipe, and heat exchange is performed through the pipe.
[0015]
Next, the incinerator 2 will be described. As an example, a known circular incinerator with an agitating device is applied. In this system, the incinerator 2 is used for incineration of the dried sludge. It is.
Then, a pipe line is connected between the exhaust port 21 in the incinerator 2 and the introduction port 33 in the heat exchanger 3, and further, a pipe line is connected between the discharge port 34 and the exhaust gas treatment device 4 in the heat exchanger 3. Thus, the incineration exhaust gas discharge path 6 is formed.
[0016]
The exhaust gas treatment device 4 includes a cooling tower 41, a bag filter 42, and an induction fan F6. After the incineration exhaust gas G2 after heat exchange is rapidly cooled with water, harmful substances such as dioxins are removed. It is configured to be released to the outside.
[0017]
The configuration of the dry incineration system S described so far is a known configuration disclosed in the patent application filed by the applicant described in the background of the invention, and the configuration unique to the present invention will be described below.
First, in the dry exhaust gas circulation path 5, an outside air introduction path 7 is provided between the exhaust port 11 in the dryer 1 and the introduction port 31 in the heat exchanger 3. In this embodiment, the dust collector 51 and the exhaust port are provided. 11 was formed.
Further, an exhaust path 8 is provided between the air supply port 12 in the dryer 1 and the exhaust port 32 in the heat exchanger 3.
The outside air introduction path 7 and the exhaust path 8 are configured to be opened and closed by a valve V1 and a valve V2, respectively.
[0018]
Further, a feedback path 9 is provided between a pipe line connected to the inlet 31 of the heat exchanger 3 and a pipe connected to the outlet 32 of the heat exchanger 3 in the dry gas circulation path 5. In this embodiment, as an example, a pipe line is connected between the front part of the dust collector 51 and the front part of the valve V4. The feedback path 9 is configured to be opened and closed by a valve V3.
[0019]
The dryer 1 can be separated from the dry exhaust gas circulation path 5 by providing a valve V4 and a valve V5 at the front stage of the air supply port 12 and the rear stage part of the exhaust port 11 in the dry exhaust gas circulation path 5, respectively. The configuration is as follows.
[0020]
The dry incineration system S of the present invention is configured as described above as an example, and the operation method thereof will be described below.
(1) Steady operation First, the operation method during the steady operation of the dry incineration system S will be described. During steady operation, the valves V1, V2, V3 are closed and the valves V4, V5 are closed as shown in FIG. Open.
As an example, the dewatered sludge treated by an appropriate dehydrator is sent to the dryer 1 with a water content of about 80%, and is dried to a water content of about 10 to 30% by the drier 1. The dry exhaust gas G1 generated by this drying is discharged from the exhaust port 11 and sent to the heat exchanger 3 through the dry exhaust gas circulation path 5.
On the other hand, in the incinerator 2, the dried sludge is incinerated, and the incineration exhaust gas G2 generated by this incineration is discharged from the exhaust port 21 at a temperature of 850 ° C. or more as an example, and heat exchange is performed through the incineration exhaust gas exhaust path 6. Sent to vessel 3.
[0021]
The incineration exhaust gas G2 sent to the heat exchanger 3 is subjected to heat exchange with the dry exhaust gas G1, and is sent to the cooling tower 41 in a state where the temperature is lowered to about 450 ° C. as an example. Further, it is rapidly cooled to about 200 ° C. (preferably 150 ° C. or lower), and harmful substances such as dioxins and mercury are removed together with hydrogen chloride gas and sulfur oxide gas by the bag filter 42 and then released to the outside. Is done.
For the incineration exhaust gas G2, lime, activated carbon or the like is added and mixed while being sent from the cooling tower 41 to the bag filter 42, and reaction and adsorption of harmful components are also performed.
[0022]
On the other hand, regarding the dry exhaust gas G1, the dry exhaust gas G1 is discharged from the dryer 1 at about 150 to 200 ° C. as an example, and after dust is removed by the dust collector 51, it is sent to the heat exchanger 3. The dry exhaust gas G1 sent to the heat exchanger 3 is subjected to heat exchange with the incineration exhaust gas G2, and is heated to about 550 to 600 ° C. as an example, and further heated by the hot air furnace 10. Supplied to the dryer 1.
A part of the dry exhaust gas G1 to be discharged out of the system is introduced into the incinerator 2 through the branch path 50, burned and deodorized here, and then released to the outside through the incineration exhaust gas discharge path 6. It becomes.
[0023]
Thus, without introducing the incineration exhaust gas G2 into the dryer 1, the temperature of the dry exhaust gas G1 is raised in the heat exchanger 3 and this dry exhaust gas G1 is used as a drying heat source. Does not adsorb toxic substances such as dioxins generated by incineration.
For this reason, the dried sludge can be reused as dried sludge fertilizer or composted as fertilizer.
[0024]
(2) Operation when the dryer is stopped Next, the operation method of the drying incineration system S when the dryer 1 is stopped due to some trouble or the supply of sludge is stopped will be described.
In such a case, the valves V1 and V2 are opened and the valves V4 and V5 are closed as shown in FIG. Note that the opening degree of the valve V3 is appropriately adjusted.
[0025]
That is, when the dryer 1 is stopped, the supply of the dry exhaust gas G1, which becomes a heat load of the incineration exhaust gas G2 in the heat exchanger 3, is stopped, so that the outside air G7 is taken in instead of the dry exhaust gas G1. .
The outside air G7 taken in from the outside air introduction path 7 is supplied to the heat exchanger 3 through the dry exhaust gas circulation path 5, where heat exchange is performed with the incineration exhaust gas G2 to lower the temperature of the incineration exhaust gas G2, and then the exhaust path 8 is discharged to the outside.
At this time, the incineration exhaust gas G2 supplied to the cooling tower 41 has been lowered to a temperature that does not exceed the processing capacity of the cooling tower 41, and thus the removal of harmful substances by the cooling tower 41 and the bag filter 42 is hindered. Therefore, it is possible to continue the operation without stopping the incinerator 2.
[0026]
The outside air G7 that reaches the heat exchanger 3 from the outside air introduction path 7 through the dry exhaust gas circulation path 5 is at a lower temperature than the dry exhaust gas G1, and therefore, heat exchange designed according to the temperature of the dry exhaust gas G1. It may be necessary to take measures to protect the vessel 3.
Specifically, a part of the heated outside air G7 discharged from the discharge port 32 is returned to the front stage portion of the introduction port 31 through the feedback path 9 by adjusting the opening degree of the valve V3. It is mixed with the outside air G7.
As a result, a gas having a temperature close to the dry exhaust gas G1 is supplied to the heat exchanger 3, and the temperature of the incineration exhaust gas G2 can be lowered without imposing a burden on the heat exchanger 3. Moreover, the dew condensation in the heat exchanger 3 can be prevented, and adhesion of dust and corrosion by acidic gas can be prevented.
[0027]
In the existing equipment, when the operation of the dryer 1 is stopped as described above, the dry exhaust gas G1 serving as the heat load of the incineration exhaust gas G2 in the heat exchanger 3 is not supplied, and the incineration exhaust gas G2 is The cooling tower 41 is supplied in a state of 850 ° C. or higher. As a result, the heat exchanger 3 and the bag filter 42 may be damaged, and the ability to remove harmful substances in the exhaust gas treatment device 4 is lowered. Therefore, it is necessary to stop the operation of the incinerator 2. It was.
[0028]
[Other embodiments]
Although the present invention is based on the above-described embodiment, the following embodiment can also be adopted based on the technical idea of the present invention.
For example, the present invention is applied to a dry incineration system S configured such that a plurality of dryers 1 and heat exchangers 3 are arranged so that the incineration exhaust gas G2 discharged from the incinerator 2 is used in multiple stages. is there. In this case, even when one dryer 1 is stopped, the remaining dryer 1 can dry the dewatered sludge and the operation of the incinerator 2 can be continued. It becomes possible to keep the operating rate of the entire S favorable.
[0029]
FIG. 3 shows an incineration drying system S that includes two dryers 1 and two heat exchangers 3 and one incinerator 2. For example, even when the dryer 1A close to the incinerator 2 is stopped, the incineration exhaust gas G2 can be supplied to the heat exchanger 3B after being cooled by heat exchange with the outside air G7 in the heat exchanger 3A. Furthermore, after this incineration exhaust gas G2 is cooled by heat exchange with the dry exhaust gas G1 in the heat exchanger 3B, it is supplied to the cooling tower 41.
For this reason, the removal of harmful substances by the cooling tower 41 and the bag filter 42 is not hindered, and the operation can be continued without stopping the incinerator 2 and the dryer 1B.
[0030]
The waste treatment system and the operation method thereof according to the present invention have been described by taking sludge drying / incineration as an example. When drying / carbonizing or drying / melting, the incinerator 2 described above is used as a carbonization furnace. By replacing with a melting furnace, the waste treatment system of the present invention and the operation method thereof can be applied. Moreover, the waste treatment system of the present invention and the operation method thereof can be applied to the case of handling not only sludge but also municipal waste as waste.
[0031]
【The invention's effect】
According to the present invention, the temperature of the dry exhaust gas G1 is indirectly increased by the incineration exhaust gas G2 and reused as the drying heat source of the dryer 1, but the incinerator 2 and the like are stopped when the dryer 1 is stopped. Therefore, the entire system can be efficiently operated.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a flow chart skeletally showing an operation state in a steady state of a dry incineration system which is an example of a waste treatment system of the present invention.
FIG. 2 is a flow chart skeletally showing an operation state when a dryer is stopped in a dry incineration system which is an example of the waste treatment system of the present invention.
FIG. 3 is a flowchart schematically showing a dry incineration system including two dryers.
FIG. 4 is a flow chart skeletally showing an existing dry incineration system.
[Explanation of symbols]
S Dry Incineration System 1 Dryer 1A Dryer 1B Dryer 10 Hot Blast Furnace 11 Exhaust Port 12 Inlet Furnace 21 Exhaust Port 3 Heat Exchanger 3A Heat Exchanger 3B Heat Exchanger 31 Inlet Port 32 Outlet Port 33 Inlet Port 34 Exhaust port 4 Exhaust gas treatment device 41 Cooling tower 42 Bag filter 5 Dry exhaust gas circulation path 50 Branch path 51 Dust collector 6 Incineration exhaust gas discharge path 7 Outside air introduction path 8 Exhaust path 9 Feedback path F5 Induction fan F6 Induction fan G1 Dry exhaust gas G2 Incineration exhaust gas G7 Outside air V1 Valve V2 Valve V3 Valve V4 Valve V5 Valve

Claims (4)

The exhaust gas discharged from the dryer for drying waste such as municipal waste and sludge is guided to the heat exchanger, and the exhaust gas discharged from the incinerator, carbonization furnace or melting furnace is separately guided to the heat exchanger. Heat exchange between the dry exhaust gas and incineration exhaust gas etc. without direct contact between them, and after raising the temperature of the dry exhaust gas, circulating the heated dry exhaust gas into the dryer and reusing it as a drying heat source In the system to
In the circulation path of the dry exhaust gas, an open air introduction path that can be opened and closed is provided between an exhaust port in the dryer and an introduction port in the heat exchanger, and an air supply port in the dryer and an exhaust port in the heat exchanger; A waste treatment system characterized in that an exhaust path to open air that can be opened and closed is provided between the two. 2. A feedback path that can be opened and closed is provided between a pipe line connected to an inlet of dry exhaust gas in the heat exchanger and a pipe line connected to an outlet of the heat exchanger. The waste treatment system according to 1. The exhaust gas discharged from the dryer for drying waste such as municipal waste and sludge is guided to the heat exchanger, and the exhaust gas discharged from the incinerator, carbonization furnace or melting furnace is separately guided to the heat exchanger. Heat exchange between the dry exhaust gas and incineration exhaust gas etc. without direct contact between them, and after raising the temperature of the dry exhaust gas, circulating the heated dry exhaust gas into the dryer and reusing it as a drying heat source In the operation of the system
During steady operation, the outside air introduction path provided between the exhaust port of the dryer and the introduction port of the heat exchanger is closed, and further provided between the supply port of the dryer and the discharge port of the heat exchanger. The exhaust route to the outside air is closed, and the temperature-controlled dry exhaust gas is circulated and introduced into the dryer.
On the other hand, when the dryer is stopped, the air supply port and the exhaust port in the dryer are closed, and the outside air introduction path provided between the exhaust port in the dryer and the introduction port in the heat exchanger is opened. Open the exhaust path to the outside air provided between the air supply port in the dryer and the exhaust port in the heat exchanger, and let the outside air taken in from the outside air introduction path heated by incineration exhaust gas etc. in the heat exchanger A method for operating a waste treatment system, characterized by exhausting to the outside. Incineration exhaust gas etc. by adjusting the opening degree of the feedback path provided between the pipeline connected to the inlet of the dry exhaust gas in the heat exchanger and the pipeline connected to the outlet of the heat exchanger The operating method of the waste treatment system according to claim 3, wherein the outside air taken in from the outside air introduction path whose temperature has been increased by is mixed with the newly taken outside air.

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