JP4161158B2 - Condensation removal prevention mechanism and condensation removal prevention method in municipal waste drying equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drying facility that performs high-temperature hot-air drying of a wet product containing a large amount of moisture, such as municipal waste, and particularly, municipal waste that can eliminate adverse effects due to dew condensation that occurs in an exhaust gas path etc. downstream of the dryer. The present invention relates to a condensation removal prevention mechanism and a condensation removal prevention method in a drying facility.
[0002]
BACKGROUND OF THE INVENTION
Conventionally, most of household waste, industrial waste, etc. discharged in cities have been landfilled or incinerated. Recently, this waste is dried to generate RDF power as, for example, solid waste fuel (hereinafter referred to as RDF). Attempts have been made to reuse them. In general, waste generated in Japan contains a lot of moisture. Therefore, in order to obtain the RDF, a drying equipment 1 'as shown in FIG. 5 is used. This drying equipment 1' The municipal waste D is fed into the dryer 2 'from the supply hopper 3', and hot air of several hundred degrees is supplied from the hot air furnace 4 'heated by the burner 4a' to dry the municipal waste D. It is.
[0003]
However, in the drying equipment 1 'having such a conventional configuration, there is a problem due to condensation occurring in the exhaust duct 10' located in the subsequent stage of the dryer 2 'and the circulation path R3'. That is, although the exhaust gas discharged from the dryer 2 'has a low humidity of around 150 ° C, its humidity is extremely high. Therefore, even during operation, the exhaust gas in the exhaust duct 10' and the circulation path R3 ' Condensation is likely to occur, and once the condensation occurs, dust will adhere to and accumulate on the condensed water, especially in the front part of the dust collector 6 ', and eventually the exhaust duct 10' and the like will be blocked. In order to avoid such a situation, it is necessary to periodically clean the inside of the exhaust duct 10 ', which causes a reduction in the operating rate of the drying facility 1' and an increase in running cost. .
[0004]
As the operation mode of the drying equipment 1 ', continuous operation for 24 hours is preferable in order to suppress the generation of toxic gas and further improve the fuel consumption. However, in many facilities, the fire is stopped every day. The current situation is that so-called daytime operations are carried out, in which the operation is stopped and the operation is started again by the next day.
In such an operation mode, it is necessary to start the operation after removing the condensed water adhering to the inside of the exhaust duct 10 'or the like every time the drying equipment 1' is started up.
[0005]
Of course, as a method for preventing the condensation generated in the exhaust duct 10 ′ and the like from being removed, the following methods can be considered, but none of them is realistic. First, it is conceivable to set the exhaust gas temperature from the dryer 2 'to be high during steady operation, but this is not realistic because the risk of fire is increased. Although it is conceivable to install heating means such as a trace heater in each of the exhaust duct 10 ', the dust collector 6', the fan 7 ', etc., it is also not practical from the viewpoint of cost.
[0006]
[Technical problem to be solved]
The present invention has been made in view of such a background, and is a novel municipal waste that can eliminate the adverse effects of dew condensation that occurs in the exhaust gas path, etc. without requiring significant changes to existing facilities. The technical problem is to develop a condensation removal prevention mechanism and a condensation removal prevention method in a drying facility.
[0007]
[Means for Solving the Problems]
That is, the dew condensation prevention mechanism in the municipal waste drying facility according to claim 1 has a supply hopper facing the inlet of the dryer, a hot air furnace connected to the hot air inlet, and a combustion type deodorizing furnace downstream of the exhaust outlet. The exhaust gas discharged from the exhaust port is subjected to combustion deodorization in the combustion deodorization furnace and then exhausted to the outside, and the exhaust gas passes through a heat exchanger using the exhaust gas of the combustion deodorization furnace in advance. In a drying facility having a structure supplied to a combustion type deodorizing furnace, for supplying a part of exhaust gas whose temperature has been raised in the heat exchanger to an exhaust duct connecting an exhaust port of the dryer and the heat exchanger The air supply flow path is formed.
According to the present invention, exhaust gas heated by the heat exchanger is supplied to the exhaust duct to raise the temperature of the exhaust duct and the like, thereby preventing condensation in the exhaust duct or removing condensed water. it can.
[0008]
According to a second aspect of the present invention, there is provided a dew condensation prevention mechanism for a municipal waste drying facility, wherein, in addition to the requirement of the first aspect, an inlet pipe for introducing outside air is connected to the exhaust duct. Is.
According to the present invention, the outside air introduced from the introduction pipe is allowed to pass through the exhaust duct, and the outside air heated by the heat exchanger is supplied again to the exhaust duct. Water can be removed.
[0009]
Furthermore, the dew condensation removal preventing mechanism in the municipal waste drying facility according to claim 3 is provided with a temperature sensor in the exhaust duct in addition to the requirement of claim 1 or 2, and further a control valve for the air supply path. It is characterized by having.
According to the present invention, by adjusting the opening of the control valve based on the detection value of the temperature sensor, the temperature in the exhaust duct or the like can be maintained at a temperature at which no condensation occurs.
[0010]
According to a fourth aspect of the present invention, there is provided a method for preventing dew condensation in a municipal waste drying facility, wherein a supply hopper is faced to the inlet of the dryer, a hot air furnace is connected to the hot air inlet, and a combustion type deodorizing furnace is provided downstream of the exhaust outlet. The exhaust gas discharged from the exhaust port is exhausted to the outside after combustion deodorization in the combustion deodorization furnace, and the exhaust gas passes through a heat exchanger using the exhaust gas of the combustion deodorization furnace in advance. In the operation of the drying equipment having a structure supplied to the combustion type deodorization furnace, a part of the exhaust gas whose temperature is increased in the heat exchanger is transferred to an exhaust duct connecting the exhaust port of the dryer and the heat exchanger. By supplying, it is characterized by preventing condensation in the exhaust duct or removing condensed water.
According to the present invention, it is possible to prevent condensation or remove condensed water in the exhaust duct or the like. In particular, during the start-up operation, the dew condensation water can be removed during a series of warm-up operations, so that the troublesome operation and the decrease in the operation rate are not caused.
[0011]
Furthermore, the dew condensation removal preventing method in the municipal waste drying facility according to claim 5 is connected to the exhaust duct in addition to the requirement of claim 4, and an introduction conduit for introducing outside air is connected to the exhaust duct. The outside air introduced from the introduction pipe is passed through the exhaust duct, and the outside air is further heated by a heat exchanger and supplied to the exhaust duct again, thereby preventing condensation in the exhaust duct or It is characterized by removing condensed water.
According to this invention, the dew condensation water which generate | occur | produced in the exhaust duct with the low humidity external air can be removed efficiently.
[0012]
Furthermore, the dew condensation removal preventing method in the municipal waste drying facility according to claim 6 is provided with a temperature sensor in the exhaust duct and a control valve for the air supply passage in addition to the requirement of claim 4 or 5. And the opening degree of the control valve is adjusted based on the detection value of the temperature sensor.
According to the present invention, by adjusting the opening degree of the control valve based on the detection value of the temperature sensor, the temperature in the exhaust duct or the like can be maintained at a temperature at which no condensation occurs, and the occurrence of condensation and condensed water It is possible to prevent a reduction in operating rate caused by dust adhering to the surface.
The above problems can be solved by using the configuration of the invention described in each of the claims as a means.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the dew condensation prevention mechanism in the municipal waste drying facility of the present invention will be described with reference to the drawings, and the dew condensation removal preventing method in the municipal waste drying facility of the present invention will be described together with its operating state.
In the figure, reference numeral 1 denotes a drying facility. This drying facility 1 has a discharge port of a supply hopper 3 facing an inlet 21 of a dryer 2, and a hot stove 4 is desired at an intake port 22. The take-out conveyor 5 faces the discharge port 23, and further, a pipe line is connected to the exhaust port 24, and the dust collector 6, the fan 7, the heat exchanger 8 and the combustion type deodorizing device 9 are connected in series by this pipe line. Is. In particular, a pipe portion from the exhaust port 24 to the heat exchanger 8 is referred to as an exhaust duct 10.
[0014]
The fan 7 is followed by an exhaust path R4 leading to the outside via the heat exchanger 8 and the combustion type deodorizing device 9, and a circulation path R3 reaching the hot stove 4 without passing through the heat exchanger 8. The circulation path R3 is provided with a valve V3.
In addition, a valve V5 is provided in a pipe line connecting the hot stove 4 and the dryer 2, and an exhaust path R5 extending from the front portion of the valve V5 to the outside is formed. Further, a valve V6 is provided for the exhaust path R5. With
[0015]
The configuration so far is the same as that of the conventional drying equipment 1 'shown in FIG. 5, and the characteristic configuration of the present invention will be described.
First, an air supply flow path R1 that leads to the exhaust duct 10 is formed between the heat exchanger 8 and the combustion type deodorizer 9, and in this embodiment, the exhaust port 24 and the heat exchanger 8 are connected to each other. Since the dust collector 6 and the fan 7 are provided in the exhaust duct 10 in the middle, the front portion of the dust collector 6 to which dust contained in the exhaust gas easily adheres is used as the connection portion of the air supply flow path R1. Incidentally, it is preferable that the connection location be as close as possible to the exhaust port 24, and a valve V4 is provided between the connection location and the exhaust port 24.
[0016]
Further, the exhaust duct 10 is provided with a temperature sensor 11, and further provided with a control valve V1 for the supply air flow path R1, and further, the connection between the valve V4 in the exhaust duct 10 and the supply air flow path R1. An inlet line R2 for introducing outside air is connected to the portion, and a valve V2 is provided for the inlet line R2.
[0017]
Subsequently, the members constituting the drying facility 1 will be described in detail. The supply hopper 3, the take-out conveyor 5 and the fan 7 are already widely used in this kind of drying facility 1 and other fields. Therefore, the description will be omitted, and only a device having a configuration that is indispensable for carrying out the present invention will be described in detail.
[0018]
First, the dryer 2 will be described. As an example of the dryer 2, a rotary drum dryer is used. The dryer 2 includes a stirring shaft provided with a stirring blade so as to pass through the vicinity of the center of the rotating drum 25. The lid member is provided with an input port 21 and an intake port 22, and the other lid member is provided with a discharge port 23 and an exhaust port 24.
Then, the material to be treated introduced from the inlet 21 is dried by being exposed to hot air blown from the inlet 22 while being agitated by the rotation of the rotary drum 25 and the stirring blade.
[0019]
Next, the hot air furnace 4 will be described. In the present embodiment, a direct-fired hot air furnace is used as an example, and a burner 4a is provided as a heat source for a furnace lined with a refractory material. The outside air introduced into the furnace is heated by the thermal power, and the exhaust gas introduced from the circulation path R3 is reheated to generate hot air necessary for drying. The hot stove 4 used in the present embodiment has a capacity capable of obtaining heated air of about 500 ° C.
[0020]
Next, the dust collector 6 will be described. In the embodiment shown in FIGS. 1, 2, and 3, a cyclone dust collector is used as an example, and this is a solid particle (dust dust) due to the swirling flow generated in the inverted conical body. ) And gas, and the solid particles are discharged from the lower part of the main body.
[0021]
Next, the heat exchanger 8 will be described. The heat exchanger 8 has two fluid flow paths as an example, and the other flow path is formed by passing a pipe through one flow path. By forming, it is an apparatus for performing heat exchange between fluids flowing through these two flow paths.
[0022]
Next, the combustion type deodorizing device 9 will be described. This device comprises a burner 9a with respect to the deodorizing furnace 9b, and the gas heated by the heat exchanger 8 is heated in the deodorizing furnace 9b. It is a device that deodorizes by burning and oxidizing.
[0023]
The dew condensation removal prevention mechanism in the municipal waste drying facility of the present invention is configured by using the above-mentioned equipment as an example, and the municipal waste drying facility of the present invention is also described below while explaining the operating state of the facility. The method for preventing condensation removal will be described.
[0024]
[Operations during startup operation]
First, a method for preventing condensation removal when starting up the drying facility 1 will be described with reference to FIG. 1. First, the burner 9a in the combustion type deodorizing device 9 is ignited until the deodorizing furnace 9b reaches a temperature sufficient for the deodorizing treatment. Perform warm-up operation.
At this time, the valve V2 is opened to take in outside air, the valve V4 and the valve V3 are closed, and the fan 7 is started with the control valve V1 opened.
[0025]
The outside air passing through the introduction pipe R2 and reaching the exhaust duct 10 passes through the dust collector 6 and the exhaust fan 7, and eventually reaches the heat exchanger 8, and is discharged from the combustion deodorizing furnace 9 here. After the temperature is raised by exchanging heat with the combustion gas, a part of the gas passes through the air supply passage R1 and eventually reaches the exhaust duct 10 again.
The circulation of gas in the exhaust duct 10 and the air supply flow path R1 is continued while taking in fresh outside air, and the condensed water generated in the exhaust duct 10 eventually evaporates gradually. Is something to go. When the temperature in the deodorizing furnace 9b rises to a temperature sufficient for performing the deodorizing process, the warming-up operation ends.
[0026]
The opening of the control valve V1 is such that the temperature of the gas in the deodorizing furnace 9b in the combustion type deodorizing device 9 can be reliably removed from the condensed water generated in the exhaust duct 10 (about 200 ° C.). It may be performed for the first time at that time.
In addition, when the valve V3 and the valve V6 are opened and the valve V5 is closed as shown in FIG. 2 during the warm-up operation as described above, a part of the high-temperature gas after passing through the exhaust duct 10 is removed. It will be discharged | emitted outside through the circulation path | route R3 and exhaust path R5, and the dew condensation water which generate | occur | produced in the circulation path | route R3 can be evaporated.
[0027]
[Operation during steady operation]
Next, a method for preventing condensation removal in the steady operation after the start-up operation will be described. After the start-up operation, the municipal waste D is thrown into the dryer 2 from the supply hopper 3. The municipal waste D is dried by the action of the hot air supplied from the hot air furnace 4 and the rotation of the rotary drum 25. It is what is done. Of course, the hot stove 4 is also preliminarily warmed up.
[0028]
During the steady operation, the valve V2 is closed as shown in FIG. 3, and the exhaust gas containing a large amount of water discharged from the exhaust port 24 reaches the dust collector 6 through the exhaust duct 10, where Then, the dust is removed, and after the deodorizing process is performed in the combustion type deodorizing device 9, it is discharged to the outside through the exhaust path R4. Further, a part of the exhaust gas is returned to the hot stove 4 by appropriately opening the valve V3 provided in the circulation path R3, and the exhaust gas is reheated by the hot stove 4 and then supplied to the dryer 2.
[0029]
When the temperature of the exhaust gas in the exhaust duct 10 decreases to about 100 ° C. during such steady operation, dew condensation occurs in the exhaust duct 10, and therefore the temperature sensor 11. The control valve V1 is opened when the detected value by the above reaches a preset value, and heat exchange is performed with the combustion gas discharged from the combustion deodorizing device 9 in the heat exchanger 8. The exhaust gas whose temperature has been raised in this way is introduced into the exhaust duct 10 through the air supply passage R1, and the temperature of the exhaust duct 10 and the circulation path R3 itself is raised to prevent the formation of condensation.
[0030]
[Other embodiments]
The present invention is based on the above-described embodiment, but the following embodiment can be adopted based on the technical idea of the present invention.
That is, in the previous basic embodiment, a cyclone is used as the dust collector 6, but a bag filter 6B as shown in FIG. In this case, normally, in order to prevent the dust and odor remaining on the filter F during the start-up operation from being sent to the combustion type deodorizer 9 that has not risen to a sufficient temperature for performing the deodorization treatment, It consists of B.
In this case, valves V7, V8, and V9 are provided before and after the bag filter 6B and to the bypass B, respectively.
[0031]
In the case of adopting the above-described configuration, the bypass B can also be regarded as a part of the exhaust duct 10, and during start-up operation, the valves V7 and V8 are closed and the valve V9 is opened. By introducing the outside air whose temperature has been raised in the exchanger 8 into the bypass B, the condensed water adhering to the bypass B can be removed.
[0032]
【The invention's effect】
According to the present invention, when performing high-temperature hot-air drying of a wet product containing a lot of moisture such as municipal waste, it is possible to prevent condensation or remove condensed water in the exhaust gas path downstream of the dryer. It can be eliminated without incurring a particularly high cost.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a skeleton diagram showing a state during startup operation of a drying facility of the present invention.
FIG. 2 is a skeleton diagram showing a state during start-up operation for evaporating condensed water in a circulation path.
FIG. 3 is a skeleton diagram showing a state of a drying facility during steady operation.
FIG. 4 is a skeleton diagram showing a drying facility using a bag filter as a dust collector.
FIG. 5 is a skeleton view showing a conventional drying facility.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Drying equipment 2 Dryer 3 Supply hopper 4 Hot-blast furnace 4a Burner 5 Take-out conveyor 6 Dust collector 6B Bag filter 7 Fan 8 Heat exchanger 9 Combustion type deodorizer 9a Burner 9b Deodorizer 10 Exhaust duct 11 Temperature sensor 21 Input port 22 Inlet port 23 Exhaust port 24 Exhaust port 25 Rotating drum B Bypass D Municipal waste F Filter R1 Air supply channel R2 Introductory channel R3 Circulation channel R4 Exhaust channel R5 Exhaust channel V1 Control valve V2 Valve V3 Valve V4 Valve V5 Valve V6 Valve V7 Valve V8 Valve V9 valve

Claims (6)

A supply hopper faces the inlet of the dryer, a hot air furnace is connected to the hot air inlet, and a combustion type deodorization furnace is provided downstream of the exhaust port, and the exhaust gas discharged from the exhaust port is converted into the combustion type deodorant. In the drying facility having a structure in which the exhaust gas is exhausted to the outside after combustion deodorization in a furnace, and the exhaust gas is supplied to the combustion type deodorization furnace after passing through a heat exchanger using the exhaust gas of the combustion type deodorization furnace in advance. In a municipal waste drying facility, characterized in that an air supply passage is formed for supplying a part of exhaust gas whose temperature is raised in an exchanger to an exhaust duct connecting an exhaust port in the dryer and the heat exchanger. Condensation removal prevention mechanism. 2. The dew condensation prevention mechanism in a municipal waste drying facility according to claim 1, wherein an introduction conduit for introducing outside air is connected to the exhaust duct. 3. The dew condensation prevention mechanism for a municipal waste drying facility according to claim 1, wherein the exhaust duct is provided with a temperature sensor, and further a control valve is provided for the air supply path. A supply hopper faces the inlet of the dryer, a hot air furnace is connected to the hot air inlet, and a combustion type deodorization furnace is provided downstream of the exhaust port, and the exhaust gas discharged from the exhaust port is converted into the combustion type deodorant. In the operation of a drying facility having a structure in which the exhaust gas is exhausted to the outside after being burned and deodorized in a furnace, and the exhaust gas is supplied to the combustion type deodorization furnace after passing through a heat exchanger using the exhaust gas of the combustion type deodorization furnace in advance. In addition, by supplying a part of the exhaust gas heated in the heat exchanger to an exhaust duct connecting the exhaust port in the dryer and the heat exchanger, dew condensation is prevented in the exhaust duct or condensed water. Condensation removal prevention method for municipal waste drying equipment, characterized by removing water. The exhaust duct is connected to an introduction pipe for introducing outside air. The outside air introduced from the introduction pipe is passed through the exhaust duct, and the outside air is heated by a heat exchanger. 5. A method for preventing condensation in a municipal waste drying facility according to claim 4, wherein condensation is prevented in the exhaust duct or condensation water is removed by supplying the exhaust duct again to the exhaust duct. The exhaust duct includes a temperature sensor, and further includes a control valve for the air supply passage, and the opening degree of the control valve is adjusted based on a detection value of the temperature sensor. The method for preventing condensation removal in the drying facility according to 4 or 5.

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