JP7572046B2 - Incineration system and incineration method - Google Patents

Description

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

In incinerators such as sewage sludge incinerators, high-temperature exhaust gas discharged from the incinerator is passed through a heat exchanger to recover part of the exhaust heat, and then dust is separated and removed in a dust collector. The exhaust gas is then passed through a flue gas treatment tower for water washing to remove components such as _SOx and HCl in the exhaust gas (see Patent Document 1).

JP 2017-227441 A

In general, the incinerator is operated by maintaining the temperature inside the incinerator at a predetermined target temperature. If the temperature inside the incinerator exceeds the target temperature, problems such as _NOx being easily generated during combustion and ash melting and adhering to the furnace walls and piping may occur.

The present invention aims to provide an incineration system and method that suppresses temperature increases inside an incinerator.

The incineration system of the present invention for achieving the above object includes a turbocharger having a compressor and a turbine, a first heat exchanger that heats the compressed gas compressed by the compressor with exhaust gas discharged from the incinerator and supplies the heated compressed gas, and a second heat exchanger that cools the compressed gas supplied from the first heat exchanger with a fluid and supplies the cooled compressed gas to the turbine, and the turbine supplies the compressed gas supplied from the second heat exchanger to the incinerator.

The incineration system and method of the present invention make it possible to suppress temperature increases inside the incinerator.

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. FIG. 3 is a diagram illustrating an example of the configuration of an incineration system 300 according to the third embodiment. FIG. 4 is a diagram illustrating an example of the configuration of an incineration system 400 according to the fourth embodiment. FIG. 5 is a diagram illustrating an example of the configuration of an incineration system 500 according to the fifth 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.

[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) and pumps 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 turbocharger 2, a fluidized air preheater 3, an air cooler 4, a cooling tower 6, a dust collector 7, a flue gas treatment tower 8, and a chimney 9. In the following, the fluidized air preheater 3 is also referred to as the first heat exchanger 3, and the air cooler 4 is also referred to as the second heat exchanger 4.

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

In recent years, the moisture content of sludge has decreased compared to the past due to improvements in the capacity of sludge dewatering machines. In addition, by drying the dewatered sludge to further reduce the moisture content of the sludge, the efficiency of sludge combustion in incinerator 1 is further improved. Therefore, in incinerator 1, as the moisture content of the sludge decreases, the sludge tends to be burned more actively, and the temperature inside the furnace may become higher than the target temperature.

Therefore, in the incineration systems in each of the following embodiments (incineration systems 100, 200, 300, 400, and 500), an air cooler 4 is provided on the outlet side of the fluidized air preheater 3 to lower the temperature of the combustion air supplied to the incinerator 1, thereby suppressing the rise in temperature inside the incinerator 1.

The turbocharger 2 has a compressor 2a and a turbine 2b connected via a rotating shaft 2c. Specifically, the compressor 2a compresses the sucked air to generate compressed gas, and supplies the generated compressed gas to the fluidized air preheater 3. In addition, the turbine 2b rotates the rotating shaft 2c by utilizing the energy of the compressed gas supplied from the fluidized air preheater 3 via the air cooler 4.

Here, the compressor 2a is driven by the rotation of the rotating shaft 2c by the turbine 2b, compressing the sucked air to generate compressed gas, and the generated compressed gas is supplied to the fluidized air preheater 3.

The fluidized air preheater 3 exchanges heat between the exhaust gas discharged from the incinerator 1 and the compressed gas supplied from the compressor 2a via line L11. Specifically, the fluidized air preheater 3 uses the exhaust gas discharged from the incinerator 1 to heat the compressed gas compressed by the compressor 2a, and supplies the heated compressed gas to the air cooler 4 via line L12. The fluidized air preheater 3 also cools the exhaust gas discharged from the incinerator 1, and supplies the cooled exhaust gas to the cooling tower 6.

The air cooler 4 exchanges heat between the compressed gas supplied from the fluidizing air preheater 3 via line L12 and the fluid supplied from the fluid supply destination (not shown). Specifically, the air cooler 4 uses the compressed gas supplied from the fluidizing air preheater 3 to heat the fluid and supplies the heated fluid to the supply destination. The air cooler 4 also cools the compressed gas supplied from the fluidizing air preheater 3 and supplies the cooled compressed gas to the turbine 2b via line L13. The turbine 2b then rotates the rotating shaft 2c using the energy of the compressed gas supplied from the air cooler 4 via line L13, and supplies the compressed gas after the energy has been used to the incinerator 1.

When the cooled compressed gas is supplied to the fluidized bed 1a of the incinerator 1, the compressed gas is used as air to fluidize the fluidized bed 1a and to combust the sludge. The cooled compressed gas may also be supplied to the so-called freeboard above the fluidized bed 1a. When the cooled compressed gas is supplied to the freeboard, the compressed gas is used as combustion air.

The cooling tower 6 is disposed downstream of the fluidized air preheater 3, and cools the exhaust gas supplied from the fluidized air preheater 3 by bringing the exhaust gas into contact with water sprayed from a spray nozzle (not shown) provided inside the cooling tower 6. The cooling tower 6 then supplies the cooled exhaust gas to the dust collector 7.

The dust collector 7 is disposed downstream of the cooling tower 6 and removes impurities from the exhaust gas supplied from the cooling tower 6. The dust collector 7 may be, for example, a ceramic dust collector with excellent heat resistance.

The flue gas treatment tower 8 is disposed at the rear of the dust collector 7, and the flue gas is introduced, for example, from the bottom of the tower. The flue gas treatment tower 8 brings the flue gas 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 by having them absorbed in the water. A chimney 9 is disposed at the top of the flue gas treatment tower 8, which releases the flue gas cleaned in the flue gas treatment tower 8 into the atmosphere.

The inducer P1 is a fan or blower that induces the exhaust gas discharged from the incinerator 1 to the flue gas treatment tower 8, where it sends the cleaned exhaust gas to the chimney 9.

In this way, in the incineration system 100 in the first embodiment, an air cooler 4 is provided between the outlet side of the fluidized air preheater 3 and the inlet side of the turbine 2b. The compressed gas cooled in the air cooler 4 is supplied to the incinerator 1 via the turbine 2b.

That is, the incineration system 100 in the first embodiment has a turbocharger 2 having a compressor 2a and a turbine 2b connected via a rotating shaft 2c, a fluidized air preheater 3 that heats the compressed gas compressed by the compressor 2a with exhaust gas discharged from the incinerator 1 and supplies the heated compressed gas to an air cooler 4, and an air cooler 4 that cools the compressed gas supplied from the fluidized air preheater 3 with a fluid and supplies the cooled compressed gas to the turbine 2b. The turbine 2b then supplies the compressed gas supplied from the air cooler 4 to the incinerator 1.

In the incineration system 100 in the first embodiment, the high-temperature compressed gas supplied from the fluidized air preheater 3 is not directly supplied to the turbine 2b, but is air-cooled, so that it is possible to suppress the temperature rise in the incinerator 1. Therefore, in the incineration system 100, it is possible to prevent _NOX and the like from being easily generated in the incinerator 1. In addition, in the incineration system 100, it is possible to prevent, for example, damage to refractories due to temperature rise and clogging of piping and the like due to adhesion of molten incineration ash.

[Second embodiment]
Next, an incineration system 200 in a second embodiment will be described. Fig. 2 is a diagram for explaining a configuration example of the incineration system 200 in the second embodiment. Below, the configuration different from the incineration system 100 explained in Fig. 1 will be explained.

The incineration system 200 in the second embodiment has a power generation system 10 in addition to the incineration system 100 described in FIG. 1.

The power generation system 10 has the function of recovering the thermal energy of the fluid circulating between the air cooler 4 and the power generation system 10 and converting it into other energy sources, forming a thermal cycle such as a Rankine cycle or a Kalina cycle that circulates a low-boiling-point medium such as low-boiling-point fluorocarbons, alternative fluorocarbons, silicon oil, petroleum-based organic compounds, ammonia, or a mixture of ammonia and water as the working medium.

The air cooler 4 exchanges heat between the compressed gas supplied from the fluidizing air preheater 3 via line L12 and the fluid supplied from the power generation system 10 via line L21. Specifically, the air cooler 4 uses the compressed gas supplied from the fluidizing air preheater 3 to heat the fluid, and supplies the heated fluid to the power generation system 10 via line L22. The air cooler 4 also cools the compressed gas supplied from the fluidizing air preheater 3, and supplies the cooled compressed gas to the turbine 2b via line L13.

That is, in the incineration system 200 in the second embodiment, the thermal energy recovered in the air cooler 4 is supplied to the power generation system 10.

This enables the power generation system 10 to generate power by using the thermal energy recovered in the air cooler 4.

The fluid flowing through lines L21 and L22 may be, for example, thermal oil, or other liquids or gases such as water (steam) or air.

In addition, the fluid flowing through lines L21 and L22 is circulated between the air cooler 4 and the power generation system 10 by pump P2, which is a circulation pump.

[Third embodiment]
Next, an incineration system 300 in the third embodiment will be described. Fig. 3 is a diagram for explaining a configuration example of the incineration system 300 in the third embodiment. Below, the configuration different from the incineration system 200 explained in Fig. 2 will be explained.

In the incineration system 300 of the third embodiment, the air cooler 4 and the dryer 20 are connected via line L21 and line L22.

The dryer 20 dries the sludge, for example, before it is incinerated in the incinerator 1. Specifically, the dryer 20 dries the sludge, for example, by using thermal energy recovered in the air cooler 4.

This allows the dryer 20 to dry sludge, for example, by utilizing the heat contained in the exhaust gas. In other words, in the incineration system 300, by connecting the air cooler 4 to equipment other than the power generation system 10, it becomes possible to utilize the heat contained in the exhaust gas for purposes other than power generation.

[Fourth embodiment]
Next, an incineration system 400 in the fourth embodiment will be described. Fig. 4 is a diagram for explaining a configuration example of the incineration system 400 in the fourth embodiment. Below, the configuration different from the incineration system 200 explained in Fig. 2 will be explained.

As shown in FIG. 4, the incineration system 400 includes, for example, the incineration system 100 described in FIG. 1, and a heat medium heater 5. Hereinafter, the heat medium heater 5 is also referred to as the third heat exchanger 5.

The fluidized air preheater 3 and the heat transfer medium heater 5 are connected in parallel, and the exhaust gas discharged from the incinerator 1 is branched into two by a line, with a portion of the exhaust gas being supplied to the fluidized air preheater 3 and the other portion being supplied to the heat transfer medium heater 5.

The fluid discharged from pump P2 (in other words, the fluid supplied from power generation system 10) is supplied to heat transfer medium heater 5 via line L23, heated by heat transfer medium heater 5, and supplied to power generation system 10 via line L24 which merges with line L22. The fluid discharged from pump P2 is also supplied to air cooler 4 via line L21, heated by air cooler 4, and supplied to power generation system 10 via line L22.

The heat medium heater 5 exchanges heat between the exhaust gas discharged from the incinerator 1 and a fluid supplied from the power generation system 10 via line L23. Specifically, the heat medium heater 5 uses the exhaust gas discharged from the incinerator 1 to heat the fluid, and supplies the heated fluid to the power generation system 10 via line L24. The heat medium heater 5 also cools the exhaust gas discharged from the incinerator 1, and supplies the cooled exhaust gas to the cooling tower 6.

The fluid flowing through lines L23 and L24, like the fluid flowing through lines L21 and L22, may be, for example, thermal oil, or may be other liquids or gases such as water (steam) or air.

Furthermore, as shown in FIG. 4, lines L21 and L23 may merge near the power generation system 10, and each may consist of two independent lines. Similarly, as shown in FIG. 4, lines L22 and L24 may merge near the power generation system 10, and each may consist of two independent lines.

That is, in the incineration system 400 in the fourth embodiment, the thermal energy recovered in the air cooler 4 and the thermal energy recovered in the heat transfer medium heater 5 are each supplied to the power generation system 10.

This enables the power generation system 10 to generate electricity by using the thermal energy recovered in the air cooler 4 and the thermal energy recovered in the heat transfer medium heater 5. Therefore, the power generation system 10 can generate electricity more efficiently by utilizing the heat contained in the exhaust gas discharged from the incinerator 1.

In the example shown in FIG. 4, lines L21 and L22 through which fluid circulates between the air cooler 4 and the power generation system 10, and lines L23 and L24 through which fluid circulates between the heat transfer medium heater 5 and the power generation system 10 are provided in parallel. That is, in the example shown in FIG. 4, a portion of the fluid from the power generation system 10 is supplied to the air cooler 4 via line L22, and another portion is supplied to the heat transfer medium heater 5 via line L23.

As a result, in the incineration system 400, it is possible to use a circulation pump (pump P2) with a lower discharge pressure than in the incineration system 500 described below. Also, in the incineration system 400, it is possible to reduce the transfer surface area in the heat transfer medium heater 5 compared to the incineration system 500 described below.

In the example shown in FIG. 4, a valve V1 is provided in the line between the fluidized air preheater 3 and the cooling tower 6, and a valve V2 is provided in the line between the heat transfer medium heater 5 and the cooling tower 6. In addition, in the example shown in FIG. 4, a valve V3 (valve V3a and valve V3b) is provided in the line L21 between the air cooler 4 and the power generation system 10.

As a result, in the incineration system 400, it becomes possible to adjust the amount of thermal energy supplied to the power generation system 10 by adjusting the flow rate, for example, using valves V1, V2, and V3. Specifically, when the temperature of the incinerator 1 exceeds a threshold value, the control device (not shown) decreases the aperture of valve V3b and increases the aperture of valve V3a in order to increase the proportion of fluid supplied to the air cooler 4 and recover more heat from the compressed gas from the turbine 2b. In addition, when the temperature of the incinerator 1 falls below the threshold value, the control device (not shown) increases the aperture of valve V3b and decreases the aperture of valve V3a.

In the example shown in FIG. 4, the fluidized air preheater 3 and the heat medium heater 5 are arranged in parallel, but the fluidized air preheater 3 and the heat medium heater 5 may be arranged directly. Specifically, in the example shown in FIG. 4, a part of the exhaust gas discharged from the incinerator 1 is supplied to the fluidized air preheater 3, and another part is supplied to the heat medium heater 5, but all of the exhaust gas discharged from the incinerator 1 may be supplied to the fluidized air preheater 3, and further, all of the exhaust gas that has passed through the fluidized air preheater 3 may be supplied to the heat medium heater 5. In addition, all of the exhaust gas discharged from the incinerator 1 may be supplied to the heat medium heater 5, and further, all of the exhaust gas that has passed through the heat medium heater 5 may be supplied to the fluidized air preheater 3.

[Fifth embodiment]
Next, an incineration system 500 in the fifth embodiment will be described. Fig. 5 is a diagram for explaining a configuration example of the incineration system 500 in the fifth embodiment. Below, the configuration different from the incineration system 400 explained in Fig. 4 will be explained.

In the incineration system 500 in the fifth embodiment, unlike the case described in FIG. 4, instead of lines L21, L22, L23, and L24, lines L25, L26, and L27 are provided that connect the air cooler 4, the heat medium heater 5, and the power generation system 10 in series. That is, in the example shown in FIG. 5, after fluid is supplied from the power generation system 10 to the air cooler 4, fluid is supplied from the air cooler 4 to the heat medium heater 5. Then, in the example shown in FIG. 5, fluid is further supplied from the heat medium heater 5 to the power generation system 10.

As a result, in the incineration system 500, it is easier to control the temperature of the fluid supplied to the power generation system 10 than in the incineration system 400 described in FIG. 4, for example.

In the example shown in FIG. 5, a bypass L28 is provided in line L25 and line L26, connecting the front and rear of the position where the air cooler 4 is provided.

As a result, in the incineration system 500, it is possible to adjust the amount of fluid supplied to the air cooler 4, for example, by adjusting the valve V4 (valve V4a and valve V4b) provided in the bypass L28. Specifically, when the temperature of the incinerator 1 exceeds a threshold value, the control device (not shown) decreases the aperture of valve V4a and increases the aperture of valve V4b in order to increase the thermal energy recovered by the air cooler 4. On the other hand, when the temperature of the incinerator 1 falls below the threshold value, the control device (not shown) increases the aperture of valve V4a and decreases the aperture of valve V4b in order to decrease the thermal energy recovered by the air cooler 4.

In the example shown in FIG. 5, a bypass L29 is provided in line L26 and line L27, connecting the front and rear of the position where the heat transfer heater 5 is provided.

As a result, in the incineration system 500, it is possible to adjust the amount of fluid supplied to the heat transfer medium heater 5, for example, by adjusting the valve V5 (valve 5a and valve V5b) provided in the bypass L29. Specifically, a control device (not shown) controls the opening and closing of valves V5a and V5b, for example, so that the outlet temperature of the heat transfer medium heater 5 becomes a target temperature.

In addition, in line L12 and line L13, for example, a bypass (not shown) may be provided that connects before and after the position where the air cooler 4 is provided. This makes it possible for the incineration system 500 to adjust the amount of compressed gas supplied to the incinerator 1.

1: incinerator 1a: fluidized bed 2: turbocharger 2a: compressor 2b: turbine 2c: rotating shaft 3: fluidized air preheater 4: air cooler 5: heat transfer heater 6: cooling tower 7: dust collector 8: flue gas treatment tower 9: chimney 10: power generation system 20: dryer 100: incineration system 200: incineration system 300: incineration system 400: incineration system 500: incineration system P1: induction machine P2: pump L11: line L12: line L13: line L21: line L23: line L24: line L25: line L26: line L27: line L28: bypass L29: bypass L31: line V1: valve V2: valve V3: valve V4: valve V5: valve

Claims (8)

A turbocharger having a compressor and a turbine;
A first heat exchanger that heats the compressed gas compressed by the compressor with exhaust gas discharged from an incinerator and supplies the heated compressed gas;
a second heat exchanger that cools the compressed gas heated in the first heat exchanger by heat exchange with a fluid and supplies the cooled compressed gas to the turbine,
The turbine supplies the compressed gas cooled in the second heat exchanger to the incinerator ,
An incineration system , wherein the fluid is a fluid circulating between the second heat exchanger and another system . In claim 1,
The second heat exchanger heats the fluid using the compressed gas supplied from the first heat exchanger, and supplies the heated fluid to a system other than the incineration system. In claim 2, further comprising:
An incineration system having a third heat exchanger that heats the fluid by the exhaust gas and supplies the heated fluid to the other system. In claim 3,
an incineration system having a supply line that supplies the fluid supplied from the other system to the second heat exchanger and the third heat exchanger. In claim 4,
The supply line is a line that connects the second heat exchanger and the third heat exchanger in parallel, and includes a line that supplies a portion of the fluid supplied from the other system to the second heat exchanger, and a line that supplies another portion of the fluid supplied from the other system to the third heat exchanger. In claim 4,
The supply line is a line that connects the second heat exchanger and the third heat exchanger in series, and includes a line that supplies the fluid supplied from the other system to the second heat exchanger, and a line that supplies the fluid supplied from the second heat exchanger to the third heat exchanger downstream of the second heat exchanger. An incinerator,
A turbocharger having a compressor and a turbine;
A first heat exchanger that heats the compressed gas compressed by the compressor with exhaust gas discharged from the incinerator and supplies the heated compressed gas;
Other systems that operate with heat provided via a fluid;
a second heat exchanger that heats the fluid by heat exchange with the compressed gas whose temperature has been raised in the first heat exchanger, supplies the heated fluid to the other system, and cools the compressed gas whose temperature has been raised in the first heat exchanger by heat exchange with the fluid, and supplies the cooled compressed gas to the turbine,
The turbine supplies the compressed gas cooled in the second heat exchanger to the incinerator ,
An incineration system , wherein the fluid is a fluid circulating between the second heat exchanger and another system . The first heat exchanger heats the compressed gas compressed by the compressor with exhaust gas discharged from the incinerator and supplies the heated compressed gas;
A second heat exchanger cools the compressed gas heated in the first heat exchanger by heat exchange with a fluid , and supplies the cooled compressed gas;
A turbine supplies the compressed gas cooled in the second heat exchanger to the incinerator ;
The incineration method , wherein the fluid is a fluid circulating between the second heat exchanger and another system .

Images