JP7613671B2 - Incineration system and incineration method - Google Patents

Description

The present invention relates to an incineration system and an incineration method.

The exhaust gas from an incinerator that incinerates materials to be incinerated such as sludge (hereinafter simply referred to as materials to be incinerated) is a high-temperature exhaust gas of around 800 to 900°C. For this reason, for example, an incineration system has been proposed that includes a waste heat power generation system in which this high-temperature exhaust gas is introduced into a boiler to generate steam, which is then used to rotate a generator using a steam turbine.

In the incineration system described above, for example, thermal energy recovered from a waste heat power generation system is used as a heat source for drying the materials to be incinerated before incineration (see Patent Document 1).

JP 2017-000983 A

In incineration systems like the one described above, it is desirable to reduce the power consumption of each device operating in the incineration system.

The incineration system of the present invention for achieving the above object comprises an incinerator, a cogeneration system that generates electricity using the thermal energy of a first heat medium heated by waste heat from the incinerator, a dryer that dries the materials to be incinerated and supplied to the incinerator using the thermal energy of a second heat medium heated by the thermal energy of the first heat medium, and equipment that operates using the thermal energy of the second heat medium.

The incineration system of the present invention makes it possible to reduce the power consumption of each operating device.

FIG. 1 is a diagram illustrating an example of the configuration of an incineration system 100 according to the first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of an incineration system 200 according to the second embodiment.

Below, an embodiment of the present invention will be described with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.

[Incineration system 100 in the first embodiment]
First, an incineration system 100 in the first embodiment will be described. Fig. 1 is a diagram for explaining a configuration example of the incineration system 100 in the first embodiment. Note that the arrangement positions and numbers of lines (pipes), pumps, etc. shown below are examples and are not limited to these.

As shown in FIG. 1, the incineration system 100 includes, for example, an incinerator 1, a heat transfer medium heater 2, a white smoke prevention air preheater 3, a flue gas treatment tower 4, a dryer 5, a scrubber 6, and a cogeneration system 10.

The incinerator 1 is, for example, a fluidized incinerator that incinerates sludge. The incinerator 1 has a so-called fluidized bed 1a. The sludge to be incinerated is also called dehydrated cake. In the following, the incinerator 1 will be described as a fluidized incinerator.

Specifically, the incinerator 1 incinerates the sludge S (hereinafter also referred to as dried sludge S) supplied from the dryer 5 by using air supplied from the combustion air fan P1 (hereinafter also referred to as the supply fan P1) via the line L11 as the combustion air. The line L11 is a pipe that connects at least the combustion air fan P1 and the incinerator 1. The incinerator 1 discharges the exhaust gas G generated by incinerating the sludge S to the line L2. The line L2 is a pipe that connects at least the incinerator 1, the heat medium heater 2, the white smoke prevention air preheater 3, and the flue gas treatment tower 4 in that order.

The heat medium heater 2 exchanges heat between the exhaust gas G supplied from the incinerator 1 via line L2 and the fluid supplied from the cogeneration system 10 via line L31. Line L31 is a pipe that connects at least the heat medium heater 2 and the cogeneration system 10. Specifically, the heat medium heater 2 uses the exhaust gas G discharged from the incinerator 1 to heat the fluid, and supplies the heated fluid to the cogeneration system 10. The heat medium heater 2 then supplies the heated exhaust gas G (cooled exhaust gas G) to the white smoke prevention air preheater 3 via line L2.

Note that, in the following description, the fluid supplied to the cogeneration system 10 via line L31 is assumed to be water (water vapor), but other types of fluids (gas or liquid) may also be supplied to the cogeneration system 10.

The white smoke prevention air preheater 3 is a heat exchanger arranged after the heat medium heater 2, and for example, by using the thermal energy of the high-temperature exhaust gas G discharged from the incinerator 1, it heats the air supplied from the white smoke prevention air fan P2 via the line L12 to generate white smoke prevention air A. The white smoke prevention air A is heated air used to prevent the water vapor in the exhaust gas G discharged from the chimney from appearing as white smoke. The line L12 is a pipe that sequentially connects at least the white smoke prevention air fan P2, the white smoke prevention air preheater 3, and the flue gas treatment tower 4 (the chimney of the flue gas treatment tower 4). The temperature of the white smoke prevention air A is, for example, about 100 to 200 ° C. The temperature of the exhaust gas G that has passed through the white smoke prevention air preheater 3 is, for example, about 200 ° C. The white smoke prevention air preheater 3 cools the exhaust gas G discharged from the incinerator 1 and supplies the cooled exhaust gas G to the exhaust gas treatment tower 4 via line L2.

The flue gas treatment tower 4 is disposed after the white smoke prevention air preheater 3, and introduces the flue gas G, for example, from the bottom of the tower. The flue gas treatment tower 4 brings the flue gas G into contact with water sprayed from a water spray nozzle (not shown) at the top, thereby removing components such as _SOx and HCl in the flue gas G by having the water absorb them. A chimney is disposed at the top of the flue gas treatment tower 4, which releases the flue gas G cleaned in the flue gas treatment tower 4 into the atmosphere.

The induction machine P3 is, for example, a fan or blower that induces the exhaust gas G discharged from the incinerator 1 to the flue gas treatment tower 4, and sends the cleaned exhaust gas G in the flue gas treatment tower 4 to the chimney.

The incineration system 100 may have, for example, a cooling tower (not shown) between the white smoke prevention air preheater 3 and the flue gas treatment tower 4, which further cools the flue gas G supplied from the white smoke prevention air preheater 3. The incineration system 100 may also have, for example, a dust collector (not shown) between the white smoke prevention air preheater 3 and the flue gas treatment tower 4, which removes (dust removes) soot from the flue gas G supplied from the cooling tower.

The cogeneration system 10 has a function of recovering the thermal energy of the fluid supplied from the heat medium heater 2 and converting it into other energy, and includes, for example, an evaporator 11, a steam turbine 12, a generator 13, and a condenser 14. In the cogeneration system 10, a heat cycle such as a Rankine cycle or a Kalina cycle is formed by circulating a working medium (not shown) in a line L32. The line L32 is a pipe that sequentially connects at least the evaporator 11, the steam turbine 12, and the condenser 14, and the working medium is circulated through the line L32 by a circulation pump (not shown). Hereinafter, the working medium circulating in the cogeneration system 10 (line L32) is also referred to as the first heat medium. The working medium is also called a working fluid, and is, for example, a low-boiling-point medium such as fluorocarbons, alternative fluorocarbons, ammonia, or a mixture of ammonia and water, which have a boiling point lower than that of water, or a high-boiling-point medium such as oil, which has a boiling point higher than that of water. In addition, the cogeneration system 10 may have, for example, a circulation pump (not shown) that circulates the working medium in line L32.

The evaporator 11 evaporates the working medium by using the thermal energy of the fluid supplied from the heat medium heater 2 via line L31.

The steam turbine 12 rotates using the working medium steam generated by the evaporator 11. The generator 13 connected to the rotating shaft of the steam turbine 12 generates electricity using the rotation of the steam turbine 12.

The condenser 14 condenses the gaseous working medium output from the steam turbine 12, for example, by a heat medium (not shown) supplied from the dryer 5 via line L33. Line L33 is a pipe that connects at least the condenser 14 and the dryer 5, and the heat medium circulates through line L33 by a circulation pump (not shown). The condenser 14 then supplies the condensed working medium to the evaporator 11, for example, by the circulation pump. Hereinafter, the heat medium circulating through line L33 and further line L33a described below is also referred to as the second heat medium.

The cogeneration system 10 may have, for example, a regenerator (not shown) in addition to the evaporator 11, steam turbine 12, generator 13, and condenser 14. The regenerator, for example, exchanges heat between the steam of the first heat medium output from the steam turbine 12 and the first heat medium condensed by the condenser 14, heats the first heat medium supplied from the condenser 14, and supplies it to the evaporator 11. In this case, the condenser 14 condenses the steam of the first heat medium supplied from the regenerator with the liquid second heat medium.

The dryer 5 is, for example, a steam dryer, and dries the sludge S (hereinafter also referred to as dehydrated sludge S) fed into the dryer by using the thermal energy of the gaseous second heat medium supplied from the condenser 14. The dryer 5 then discharges the dried sludge S (dried sludge S) into line L4, and discharges the air generated by drying the sludge S into line L13. The line L4 is a pipe that connects at least the dryer 5 and the incinerator 1. The line L13 is a pipe that connects at least the dryer 5, the scrubber 6, and the incinerator 1 in sequence.

The scrubber 6, for example, removes water vapor contained in the air supplied from the dryer 5. The scrubber 6 then supplies the air from which the water vapor has been removed as combustion air to the incinerator 1, for example, by using the combustion air fan P4 (hereinafter also referred to as the supply fan P4).

In other words, if air from which water vapor has not been sufficiently removed is supplied to the incinerator 1, it may be necessary to use extra heat to raise the temperature of the incinerator 1, or it may not be possible to sufficiently recover heat in the downstream stage of the incinerator 1 (e.g., the heat transfer medium heater 2). For this reason, in the incineration system 100, air from which water vapor has been removed in the scrubber 6 is supplied to the incinerator 1.

In addition, in the incineration system 100, the air supplied from the dryer 5 is combusted in the incinerator 1 as combustion air, thereby also performing deodorization processing on the air supplied from the dryer 5.

Furthermore, the condenser 14 supplies at least a portion of the second heat medium to the induction machine P3 via line L33a branched off from line L33. The induction machine P3 is an example of a device that operates using the thermal energy of the second heat medium. Line L33a is a pipe that branches off from line L33 (a line that supplies the second heat medium from the condenser 14 to the dryer 5) and then merges again with line L33 (a line that supplies the second heat medium from the dryer 5 to the condenser 14) via the induction machine P3. The induction machine P3 is then operated by the thermal energy of the second heat medium supplied from the condenser 14. The induction machine P3 then supplies the second heat medium to the dryer 5 via line L33.

Specifically, the induction machine P3 has, for example, a turbine (not shown) and a fan (not shown) connected to the turbine. The induction machine P3 rotates the turbine using, for example, a second heat medium (e.g., steam) supplied from the condenser 14, which in turn rotates the fan, thereby inducing the exhaust gas G to the flue gas treatment tower 4.

The following describes the supply control of the second heat medium to the dryer 5 and the induction machine P3. The heat energy required for the dryer 5 to dry the dewatered sludge S varies depending on the properties of the sludge, such as the moisture content of the dewatered sludge S and the heat value of the organic matter contained in the dewatered sludge S. Therefore, for example, if it is determined that it is not appropriate to supply all of the second heat medium supplied from the condenser 14 to the dryer 5 based on the properties of the dewatered sludge S measured by an instrument (not shown) attached to the front stage of the dryer 5, the incineration system 100 supplies a portion of the second heat medium supplied from the condenser 14 to the induction machine P3. In this case, the incineration system 100 uses the heat energy of the second heat medium supplied from the condenser 14 as power for the induction machine P3.

Specifically, for example, if the measured moisture content of the dewatered sludge S is lower than a predetermined threshold, the worker determines that the dewatered sludge S does not need to be sufficiently dried in the dryer 5, and supplies a portion of the second heat medium supplied from the condenser 14 to the inducer P3. On the other hand, for example, if the measured moisture content of the dewatered sludge S is higher than a predetermined threshold, the worker determines that the dewatered sludge S needs to be sufficiently dried in the dryer 5, and supplies all of the second heat medium supplied from the condenser 14 to the dryer 5.

As a result, in the incineration system 100 of this embodiment, it is possible to reduce the power required to drive the attractant P3, thereby achieving power savings.

In addition, the operator may supply a portion of the second heat medium supplied from the condenser 14 (e.g., a fixed amount of the second heat medium) to the induction machine P3, regardless of the properties of the dewatered sludge S. This allows the incineration system 100 in this embodiment to stably suppress the power required to drive the induction machine P3, for example.

The operator may also adjust the amount of the second heat medium supplied to the induction machine P3, for example, by controlling the opening and closing of a valve (not shown) provided in the line L33 that supplies the second heat medium from the condenser 14 to the dryer 5.

The operator may also determine whether or not to supply a portion of the second heat transfer medium supplied from the condenser 14 to the induction machine P3 based on the properties of the dried sludge S measured, for example, by an instrument (not shown) attached to the rear of the dryer 5 and the front of the incinerator 1 (line L4).

The incineration system 100 may also have, for example, a control device (not shown) that controls the amount of the second heat medium supplied to the induction machine P3. The control device is, for example, a computer having a CPU (Central Computing Unit) and memory, etc. The control device may also automatically control the amount of the second heat medium supplied to the induction machine P3 based on, for example, the measured moisture content of the dewatered sludge S.

Specifically, the control device may control, for example, when the moisture content of the dewatered sludge S is higher than a predetermined threshold, by controlling the valve provided on the line L33a to close, so that all of the second heat medium supplied from the condenser 14 is supplied to the dryer 5. Also, the control device may control, for example, when the moisture content of the dewatered sludge S is lower than a predetermined threshold, by controlling the valve provided on the line L33a to open, so that a part of the second heat medium supplied from the condenser 14 is supplied to the induction machine P3. More specifically, the control device may control, for example, when the moisture content of the dewatered sludge S is lower than a predetermined threshold, by controlling the valve provided on the line L33 to open and close so that the amount of the second heat medium supplied to the induction machine P3 increases as the moisture content of the dewatered sludge S decreases.

In the above example, a case was described in which a portion of the second heat medium supplied from the condenser 14 was supplied to the induction machine P3, but, for example, a portion of the second heat medium supplied from the condenser 14 may be supplied to other equipment, and the thermal energy of the second heat medium may be used to power the other equipment. Specifically, in the incineration system 100, for example, a portion of the second heat medium supplied from the condenser 14 may be supplied to the combustion air fan P1, the white smoke prevention air fan P2, and the combustion air fan P4.

In the above example, the dryer 5 is a steam dryer, and the second heat transfer medium circulating between the dryer 5 and the condenser 14 (line L33) is, for example, water (steam), but this is not limited to the above. Specifically, for example, the dryer 5 may be a heat transfer oil dryer, and heat transfer oil may circulate between the dryer 5 and the condenser 14.

[Incineration system 200 according to the second embodiment]
Next, an incineration system 200 in the second embodiment will be described. Fig. 2 is a diagram for explaining a configuration example of the incineration system 200 in the second embodiment. Note that only the points different from the incineration system 100 in the first embodiment will be described below.

As shown in FIG. 1, the incineration system 200 includes, for example, an incinerator 1, a white smoke prevention air preheater 3, a flue gas treatment tower 4, a dryer 5, a scrubber 6, and a cogeneration system 10.

The cogeneration system 10 in this embodiment has the function of recovering the thermal energy of the exhaust gas G discharged from the incinerator 1 and converting it into other energy sources, and includes, for example, an evaporator 11, a steam turbine 12, a generator 13, and a condenser 14.

Furthermore, in this embodiment, the evaporator 11 evaporates the working medium by using the thermal energy of the exhaust gas G supplied from the incinerator 1 via the line L2. The evaporator 11 then supplies the exhaust gas G to the white smoke prevention air preheater 3.

In other words, in the incineration system 200 of this embodiment, for example, a heat exchanger (heat medium heater 2 in the incineration system 100) for performing heat exchange between the exhaust gas G supplied from the incinerator 1 through the line L2 and a fluid for supplying thermal energy to the cogeneration system 10 is not used, but instead the exhaust gas G discharged from the incinerator 1 is directly supplied to the evaporator 11, and the first heat medium in the cogeneration system 10 is directly heated by the thermal energy of the exhaust gas G. That is, the evaporator 11 directly heats and evaporates the first heat medium by the thermal energy of the exhaust gas from the incinerator 1 without the intervention of another heat medium. In other words, in the incineration system 100 of this embodiment, the thermal energy of the exhaust gas G is directly recovered by the evaporator 11 without the intervention of the heat medium heater 2, and the recovered thermal energy is supplied to the first heat medium.

As a result, in the incineration system 200 of this embodiment, it is possible to reduce the number of heat exchangers, and it is possible to reduce the loss of thermal energy due to heat exchange in the heat exchangers. Therefore, in the incineration system 200 of this embodiment, it is possible to increase the amount of power generation in the cogeneration system 10.

In the present invention described above, for example, by supplying at least a portion of the second heat medium supplied from the condenser 14 to equipment such as the induction machine P3, and using the thermal energy of the second heat medium supplied from the condenser 14 to power the equipment, it is possible to reduce the power consumption of each equipment.

The dryer 5 may be a hot air dryer or a band dryer. When the dryer 5 is a hot air dryer or a band dryer, a drying air fan that discharges the drying air to be supplied to the dryer 5 and a heat exchanger are separately provided. This heat exchanger exchanges heat between the drying air discharged by the drying air fan and the second heat medium to raise the temperature of the drying air. In addition, the line L33 is arranged so that the second heat medium circulates between the heat and power cogeneration system 10 and this heat exchanger.

The dryer 5 dries the sludge with heated drying air. The dryer 5 may supply all of the dried drying air to the incinerator 1, or may supply a portion of the dried drying air to the incinerator 1 and supply the other dried drying air to the primary side of the drying air fan.

1: Incinerator 1a: Fluidized bed 2: Heat transfer heater 3: White smoke prevention air preheater 4: Exhaust heat treatment tower 5: Dryer 6: Scrubber 10: Combined heat and power supply system 11: Evaporator 12: Steam turbine 13: Generator 14: Condenser 100: Incineration system 200: Incineration system A: White smoke prevention air G: Exhaust gas L1: Line L2: Line L11: Line L12: Line L13: Line L31: Line L32: Line L33: Line L33a: Line P1: Combustion air fan P2: White smoke prevention air fan P3: Inducer P4: Combustion air fan S: Sludge

Claims (7)

An incinerator,
A cogeneration system for generating electricity using thermal energy of a first heat medium heated by waste heat from the incinerator;
A dryer that dries the material to be incinerated to be supplied to the incinerator by the thermal energy of a second heat medium heated by the thermal energy of the first heat medium;
An incineration system comprising: an equipment other than the dryer, the equipment being operated by thermal energy of the second heat medium. The incineration system according to claim 1, wherein the equipment is an induction fan that draws exhaust gas discharged from the incinerator into the flue gas treatment tower, an induction fan that discharges the treated exhaust gas outside the flue gas treatment tower, or a supply fan that supplies air to the incinerator. The incineration system of claim 1, further comprising a control device that controls the amount of the second heat medium supplied to the equipment and the amount of the second heat medium supplied to the dryer based on the properties of the material to be incinerated. The incineration system of claim 1, wherein the cogeneration system directly heats the first heat medium with the waste heat. The cogeneration system comprises:
a generator having a turbine rotated by the thermal energy of the first heat medium;
2. The incineration system of claim 1, further comprising: a condenser for condensing the first heat transfer medium from the turbine. The cogeneration system includes an evaporator that directly heats and evaporates the first heat medium by thermal energy of the exhaust gas from the incinerator without using another heat medium,
The incineration system according to claim 5 , wherein the generator rotates the turbine using the first heat medium evaporated by the evaporator. An incineration method in an incineration system including an incinerator, a cogeneration system for generating electricity using thermal energy of a first heat medium heated by waste heat from the incinerator, a dryer for drying materials to be incinerated to be supplied to the incinerator using thermal energy of a second heat medium heated by the thermal energy of the first heat medium , and a device other than the dryer that operates using the thermal energy of the second heat medium,
An incineration method comprising controlling the amount of the second heat medium supplied to the equipment and the amount of the second heat medium supplied to the dryer based on the properties of the material to be incinerated.

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