Waste incineration system and waste incineration method

Abstract

To efficiently recover carbon dioxide from exhaust gas generated through incineration while suppressing energy consumption.SOLUTION: A waste incineration system includes: an incinerator for burning waste while conveying the waste in the combustion chamber with a fire grate; dust removal means for removing dust from exhaust gas discharged from the incinerator; mixed gas supply means for supplying mixed gas obtained by mixing gas containing oxygen and part of exhaust gas from which dust has been removed by the dust removal means to the combustion chamber; cleaning means for cleaning the exhaust gas from which dust has been removed by the dust removal means; and liquefaction means for directly liquefying carbon dioxide included in the exhaust gas cleaned by the cleaning means without interposing a device for separation and recovery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a waste incineration system and a waste incineration method. [Background technology]

[0002] As a technology for separating and capturing carbon dioxide contained in combustion exhaust gas, for example, there is a CO2 separation and capture device described in Non-Patent Document 1. This CO2 separation and capture device captures carbon dioxide by bringing exhaust gas containing carbon dioxide into contact with an amine-based CO2 absorption liquid, and the captured carbon dioxide is stored in a storage tank and then reused as a resource. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Fujita, Kishio, Muraoka, Daigo, Saito, "Environmentally Friendly CO2 Separation and Capture System," Toshiba Review, May 2015, Vol. 70, No. 5, pp. 12-15 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when recovering and utilizing carbon dioxide from the flue gas of a waste incineration facility, the carbon dioxide is separated and recovered from the flue gas, and the recovered carbon dioxide is compressed and cooled to become liquefied carbon dioxide, reducing its volume before being stored or transported. However, because the concentration of carbon dioxide in the flue gas is low, an extremely large amount of energy is required to separate and recover the carbon dioxide, as well as to compress and cool it. In other words, recovering and utilizing carbon dioxide from flue gas requires enormous energy costs.

[0005] The present invention has been made in view of the above, and has an object to efficiently recover carbon dioxide from exhaust gas generated by incineration while reducing energy consumption. [Means for solving the problem]

[0006] A waste incineration system according to one aspect of the present invention comprises an incinerator that burns waste while transporting the waste in a combustion chamber having a grate, a dust removal means that removes dust from exhaust gas discharged from the incinerator, a mixed gas supply means that supplies a mixed gas obtained by mixing an oxygen-containing gas with a portion of the exhaust gas that has been dust removed by the dust removal means to the combustion chamber, a cleaning means that cleans the exhaust gas that has been dust removed by the dust removal means, and a liquefaction means that directly liquefies the carbon dioxide contained in the exhaust gas that has been cleaned by the cleaning means without going through a device that separates and recovers the carbon dioxide.

[0007] In the waste incineration system according to one aspect of the present invention, the concentration of carbon dioxide in the exhaust gas sent from the cleaning means to the liquefying means may be 45% or more.

[0008] A waste incineration method according to one aspect of the present invention is a waste incineration method for recovering carbon dioxide contained in exhaust gas discharged from an incinerator that burns waste while transporting the waste in a combustion chamber having a grate, in which the exhaust gas discharged from the incinerator is de-dusted by a de-dusting means, a mixed gas obtained by mixing an oxygen-containing gas with a portion of the exhaust gas that has been de-dusted by the de-dusting means is supplied to the combustion chamber, the exhaust gas that has been de-dusted by the de-dusting means is washed by a cleaning means, and the carbon dioxide contained in the exhaust gas that has been cleaned by the cleaning means is directly liquefied by a liquefaction means without going through a device that separates and recovers the carbon dioxide. [Effects of the Invention]

[0009] According to the present invention, carbon dioxide can be efficiently recovered from exhaust gas generated by incineration while reducing energy consumption. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a waste incineration system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a graph showing the relationship between the carbon dioxide concentration in the exhaust gas and the energy consumption involved in liquefying the carbon dioxide. [Figure 3] FIG. 3 is a graph showing the relationship between the carbon dioxide concentration in the exhaust gas and the energy consumption of the entire waste incineration system when the carbon dioxide concentration is 45% or higher. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments described below. In addition, in the description of the drawings, the same or corresponding elements are appropriately designated by the same reference numerals. Furthermore, it should be noted that the drawings are schematic, and the dimensional relationships between the elements may differ from the actual ones.

[0012] 1 is a diagram showing the configuration of a waste incineration system 1000 according to an embodiment of the present invention. The waste incineration system 1000 includes a waste incinerator 1 that employs a combustion technology known as O2 / CO2 combustion or Oxy-fuel combustion.

[0013] The waste incinerator 1 is, for example, a grate-type incinerator, and is equipped with a combustion chamber 2 and an inlet 3. The inlet 3 is an inlet for feeding waste W, such as industrial waste or household garbage, into the combustion chamber 2, and is provided above the combustion chamber 2 on the upstream side of the flow of the waste W within the combustion chamber 2. An extruder (not shown) is disposed below the inlet 3 to push the fed waste W into the combustion chamber 2, and the waste W fed into the inlet 3 is pushed into the combustion chamber 2 by the extruder.

[0014] A grate 5 is installed at the bottom of the combustion chamber 2 to burn the waste W as it moves. The grate 5 is composed of a drying grate 5a, a combustion grate 5b, and a post-combustion grate 5c, and is arranged in this order from the inlet 3 side in the direction of movement of the waste W. The drying grate 5a mainly dries, ignites, and initially burns the waste W. The combustion grate 5b mainly pyrolyzes and partially oxidizes the waste W. The combustion grate 5b also combusts the solids and pyrolysis gases generated by pyrolysis, including carbon monoxide and hydrocarbons. The post-combustion grate 5c performs post-combustion, completely burning the unburned waste W. This post-combustion forms a layer of incineration ash on the post-combustion grate 5c after complete combustion. This incineration ash is discharged from the combustion chamber 2 through a discharge section 6 located downstream of the post-combustion grate 5c in the flow of the waste W.

[0015] A boiler 4 is connected above the combustion chamber 2 on the downstream side in the flow direction of the waste W. Near the inlet of the boiler 4, a secondary combustion chamber 11 is formed, which burns unburned gas in the gas discharged from the combustion chamber 2. Secondary combustion gas is blown into the secondary combustion chamber 11 from an injection nozzle 40 by a supply line 31e equipped with a blower and damper (not shown). In the secondary combustion chamber 11, unburned components in the combustion gas generated in the combustion chamber 2 undergo secondary combustion, and the boiler 4 recovers heat from the exhaust gas after secondary combustion.

[0016] The boiler 4, which recovers heat from exhaust gas, has two bends 12 and 13 that bend the flow path of the exhaust gas. These bends 12 and 13 form, from the upstream side along the flow direction of the exhaust gas, a first radiant chamber 14, a second radiant chamber 15, and a convective heat transfer chamber 16. The first radiant chamber 14, through which exhaust gas flows from the waste incinerator 1, has an upstream portion along the flow direction of the exhaust gas that serves as the secondary combustion chamber 11. The first radiant chamber 14 and the second radiant chamber 15 are connected via the bend 12, and the lower part of the second radiant chamber 15 and the lower part of the convective heat transfer chamber 16 are connected via the bend 13. The upper end of the convective heat transfer chamber 16 is connected via a flue 21 to a dust removal device 23 composed of a bag filter or the like.

[0017] The boiler 4 has an inner wall made of a refractory wall, and the first radiant chamber 14 and the second radiant chamber 15 have heat transfer tubes (not shown) formed of piping for circulating steam that are densely arranged outside the refractory wall that forms the inner wall. The heat transfer tubes arranged outside the refractory wall and through which water flows become a radiant heat transfer surface that receives radiant heat from the exhaust gas and generates steam, and function as an evaporator.

[0018] The convection heat transfer chamber 16 has heat transfer tubes (not shown) arranged in a flag shape at the most upstream portion in the direction of exhaust gas flow. The heat transfer tubes cool the exhaust gas flowing into the convection heat transfer chamber 16, solidifying gaseous or mist-like dust components and separating them as dust from the exhaust gas. The convection heat transfer chamber 16 also includes, from the upstream side in the direction of exhaust gas flow, three superheaters 16A and an economizer 16B. The superheater 16A includes a heat transfer tube group consisting of multiple heat transfer tubes arranged horizontally and arranged in multiple vertical stages, and the heat transfer tube group functions as a convection heat transfer surface. The superheater 16A further superheats the steam generated in the first radiation chamber 14 and the second radiation chamber 15 through heat exchange with the exhaust gas, producing high-temperature, high-pressure superheated steam.

[0019] The economizer 16B is provided downstream of the superheater 16A in the direction of exhaust gas flow, and is provided with heat transfer tubes (not shown). Steam generated in the boiler 4 and used to drive a steam turbine (not shown) is condensed in a condenser (not shown) and flows through the heat transfer tubes of the economizer 16B. The condensate flowing through the heat transfer tubes of the economizer 16B is heated by the heat retained in the exhaust gas after the steam is superheated by the superheater 16A, and the heated water is supplied to the heat transfer tubes of the first radiant chamber 14 and the second radiant chamber 15, which function as evaporators. The economizer 16B may be provided outside the boiler 4, downstream of the boiler 4 in the direction of exhaust gas flow, rather than within the convection heat transfer chamber 16. Alternatively, both an economizer inside the boiler 4 and an economizer outside the boiler 4 may be provided.

[0020] The exhaust gas from which heat has been recovered by the boiler 4 flows through a flue 21 to a dust removal device 23, which is, for example, a bag filter. In the flue 21, chemicals such as hydrated lime and activated carbon are injected into the exhaust gas together with carbon dioxide from a chemical supply device 22. By injecting the chemicals into the exhaust gas, the chemicals bind to pollutants such as hydrogen chloride and sulfur oxides contained in the exhaust gas.

[0021] The dust remover 23, which is an example of a dust removal means, removes dust by collecting chemicals that combine with dust and pollutants contained in the exhaust gas that has flowed through the flue 21. An induced draft fan 24 is connected to the dust remover 23. The induced draft fan 24 draws the exhaust gas from which dust has been removed from the dust remover 23. The exhaust gas drawn by the induced draft fan 24 is sent to the wet scrubber 51.

[0022] The wet scrubber 51 is an exhaust gas scrubbing means that scrubs exhaust gas. For example, the wet scrubber 51 brings an aqueous sodium hydroxide solution into contact with the exhaust gas to remove moisture, sulfides, chlorides, and the like from the exhaust gas. The exhaust gas scrubbed by the wet scrubber 51 and containing carbon dioxide is branched and sent to the liquefaction unit 120 and the separation unit 52. The separation unit 52 separates carbon dioxide (CO2) from the exhaust gas from which moisture has been removed by the wet scrubber 51, for example, by pressure swing adsorption (PSA). The carbon dioxide separated by the separation unit 52 is sent to the exhaust gas supply line 30. Note that the separation unit 52 may also separate nitrogen (N2) from the exhaust gas from which moisture has been removed by pressure swing adsorption, thereby increasing the carbon dioxide concentration in the exhaust gas. Alternatively, the exhaust gas induced by the induced draft fan 24 may be branched from the wet scrubber 51 on the induced draft fan 24 side and directly supplied to the exhaust gas supply line 30.

[0023] The exhaust gas supply line 30 is connected to dampers 32a, 32b, 32d, and 32e, and also to a damper 34c.

[0024] Damper 32a is connected to damper 34a, and damper 32b is connected to damper 34b. Damper 32d is connected to a rear nozzle 39 provided in combustion chamber 2, and damper 32e is connected to a supply line 31e, which will be described later.

[0025] The waste incineration system 1000 also includes an oxygen supply line 35, a blower 36, and an oxygen supplier 60. The oxygen supply line 35 is connected to the blower 36, which is connected to the oxygen supplier 60. The oxygen supplier 60 separates oxygen from air using techniques such as cryogenic separation or PSA, and generates and supplies gas (O2-based gas) with an O2 concentration of 50% or more and close to 100%. The blower 36 sends the O2-based gas supplied from the oxygen supplier 60 to the oxygen supply line 35. The oxygen supply line 35 is connected to dampers 37a to 37c and 37e that adjust the flow rate of the O2-based gas.

[0026] Damper 37a is connected to damper 34a and damper 32a, damper 37b is connected to damper 34b and damper 32b, and damper 37c is connected to damper 34c and exhaust gas supply line 30. Damper 37e is connected to supply line 31e.

[0027] The O2-based gas that passes through damper 37a from oxygen supply line 35 is mixed with the exhaust gas flowing from damper 32a and flows to damper 34a, the O2-based gas that passes through damper 37b from oxygen supply line 35 is mixed with the exhaust gas flowing from damper 32b and flows to damper 34b, the O2-based gas that passes through damper 37c from oxygen supply line 35 is mixed with the exhaust gas flowing from exhaust gas supply line 30 and flows to damper 34c, and the O2-based gas that passes through damper 37e from oxygen supply line 35 is mixed with the exhaust gas that has passed damper 32e and flows to supply line 31e.

[0028] Damper 34a adjusts the flow rate of the mixed gas obtained by mixing the O2-based component gas and exhaust gas. The mixed gas whose flow rate has been adjusted by damper 34a is supplied to wind box 7a via supply line 31a. Damper 34b adjusts the flow rate of the mixed gas obtained by mixing the O2-based component gas and exhaust gas. The mixed gas whose flow rate has been adjusted by damper 34b is supplied to wind box 7b via supply line 31b. Damper 34c adjusts the flow rate of the mixed gas obtained by mixing the O2-based component gas and exhaust gas. The mixed gas whose flow rate has been adjusted by damper 34c is supplied to wind box 7c via supply line 31c.

[0029] The wind boxes 7a to 7c are provided below the combustion chamber 2. Specifically, the wind box 7a is provided below the drying grate 5a, the wind box 7b is provided below the combustion grate 5b, and the wind box 7c is provided below the post-combustion grate 5c. The wind box 7a supplies the mixed gas to the drying grate 5a, the wind box 7b supplies the mixed gas to the combustion grate 5b, and the wind box 7c supplies the mixed gas to the post-combustion grate 5ca. Alternatively, the damper 32a and the damper 37a may be directly connected to the wind box 7a, the damper 32b and the damper 37b may be directly connected to the wind box 7b, and the exhaust gas supply line 30 and the damper 37c may be directly connected to the wind box 7c, thereby mixing the exhaust gas and the O2-based gas in the wind boxes 7a to 7c. The wind boxes 7a to 7c, supply lines 31a to 31c, 31e, dampers 32a, 32b, 32d, 32e, dampers 34a to 34c, and dampers 37a to 37c, 37e are an example of a mixed gas supply means that mixes exhaust gas and O2-based gas and supplies the mixture.

[0030] A front-stage nozzle 38 and a rear-stage nozzle 39 are provided in the combustion chamber 2. The front-stage nozzle 38 and the rear-stage nozzle 39 each function as a counterflow nozzle.

[0031] The front-stage nozzle 38 is provided above the gap between the drying grate 5a and the combustion grate 5b, for example, on the ceiling of the combustion chamber 2. The front-stage nozzle 38 is supplied with an oxidizer adjusted to have a relatively high O2 concentration, for example, an O2-containing gas adjusted to an O2 concentration of 15% or more and 25% or less.

[0032] The rear nozzle 39 is provided above and between the combustion grate 5b and the rear combustion grate 5c, for example, on the ceiling of the combustion chamber 2. Exhaust gas mainly composed of exhaust gas and having a relatively low O2 concentration, for example, an O2 concentration adjusted to less than 5%, is supplied to the rear nozzle 39. Note that gas whose O2 concentration is adjusted by mixing an O2-containing gas or an O2-based gas with the exhaust gas may also be supplied to the rear nozzle 39.

[0033] An injection nozzle 40 is provided in the secondary combustion chamber 11 at the outlet of the combustion chamber 2. The injection nozzle 40 is connected to a supply line 31e that is connected to a damper 32e and a damper 37e. The injection nozzle 40 is supplied with a secondary combustion gas having an O2 concentration adjusted to be higher than 25% and equal to or lower than 35%, for example, as an oxidizer adjusted to have a relatively high O2 concentration.

[0034] The liquefaction device 120 is a device that liquefies the carbon dioxide contained in the exhaust gas. The liquefaction device 120 liquefies the carbon dioxide contained in the exhaust gas by cleaning, compressing, deodorizing, dehumidifying, and cooling the exhaust gas.

[0035] A sensor group 71 is provided upstream in the direction of transport of the waste W within the combustion chamber 2. The sensor group 71 measures at least the temperature, O2 concentration, and carbon monoxide concentration (CO concentration) at the installed position. The sensor group 71 transmits the measured values of the temperature, O2 concentration, CO concentration, etc. to the control unit 70.

[0036] A sensor group 72 is provided downstream in the direction of transport of the waste W within the combustion chamber 2. The sensor group 72 measures at least the temperature, O2 concentration, CO concentration, and nitrogen oxide concentration (NOx concentration) at the installed position. The sensor group 72 outputs the measured temperature, O2 concentration, CO concentration, and NOx concentration. x The measured values such as concentration are transmitted to the control unit 70.

[0037] Furthermore, a sensor group 73 is provided at the outlet of the combustion chamber 2. The sensor group 73 measures at least the temperature, O2 concentration, H2O concentration, CO2 concentration, and CO concentration at the installation position. The sensor group 73 transmits the measured values of the temperature, O2 concentration, H2O concentration, CO2 concentration, CO concentration, etc. to the control unit 70.

[0038] Specifically, the control unit 70 includes a processor such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an FPGA (Field-Programmable Gate Array), and a main memory such as a RAM (Random Access Memory) or a ROM (Read Only Memory) (none of which are shown). The control unit 70 may also be configured as an information processing device such as a computer equipped with a memory. In this case, the memory included in the control unit 70 includes a storage medium selected from volatile memory such as RAM, non-volatile memory such as ROM, erasable programmable read-only memory (EPROM), a hard disk drive (HDD), and removable media. The removable media may be, for example, a universal serial bus (USB) memory or a disc storage medium such as a compact disc (CD), a digital versatile disc (DVD), or a Blu-ray disc (BD). The storage may also be configured using a computer-readable storage medium such as an externally attachable memory card. The control unit 70 controls the dampers 32a, 32b, 32d, 32e, 34a to 34e, and dampers 37a to 37c and 37e based on the measurement results of the sensor group 71 and the sensor group 72.

[0039] In the waste incineration system 1000, the mixing ratio of the exhaust gas and the O2-based gas in the mixed gas can be adjusted by controlling the dampers 32a, 32b, 32e and dampers 37a-37c, 37e. That is, the control unit 70 can control the flow rate of the exhaust gas by controlling the dampers 32a, 32b, 32e, and the flow rate of the O2-based gas by controlling the dampers 37a-37c, 37e. The control unit 70 can also control the O2 concentration of the O2-containing gas supplied to the front nozzle 38. With the above configuration, the control unit 70 can independently control the O2 concentration of the gas supplied to the wind boxes 7 (7a-7c), the grates 5 (5a-5c), the front nozzle 38, and the rear nozzle 39.

[0040] In this embodiment, a mixed gas containing carbon dioxide and high concentrations of O2 contained in the circulated exhaust gas is supplied to the drying grate 5a, the combustion grate 5b, and the post-combustion grate 5c. Compared to conventional incinerators that supply air to the grate 5, this mixed gas contains less nitrogen, resulting in a high concentration of carbon dioxide in the exhaust gas generated in the combustion chamber 2. When the carbon dioxide concentration in the exhaust gas is low, gases other than carbon dioxide, which make up the majority of the exhaust gas, must also be compressed and cooled, requiring a large amount of energy to liquefy the carbon dioxide. On the other hand, in this embodiment, the concentration of carbon dioxide in the exhaust gas is high, allowing the liquefaction device 120 to efficiently liquefy the carbon dioxide and reduce the energy consumed for liquefaction. Furthermore, in this embodiment, the chemical supply device 22 injects a chemical into the exhaust gas together with carbon dioxide, thereby preventing a decrease in the concentration of carbon dioxide contained in the exhaust gas. Furthermore, in this embodiment, amines are not used to capture carbon dioxide. This prevents the release of amines into the atmosphere and the generation of nitrosamines, which are harmful to ecosystems, thereby reducing the environmental impact. Furthermore, in this embodiment, the carbon dioxide discharged from the wet scrubber 51 is liquefied without separating and recovering carbon dioxide from the exhaust gas before liquefaction, so liquefaction can be carried out efficiently and the energy consumed for liquefaction can be reduced.

[0041] In the present invention, the oxygen concentration in the O2-based gas supplied to the oxygen supply line 35 is preferably, for example, 80% or more. Table 1 shows the relationship between the oxygen concentration in the O2-based gas supplied to the oxygen supply line 35 and the carbon dioxide concentration in the exhaust gas discharged from the wet scrubber 51, when the oxygen ratio, which is the ratio of the amount of oxygen supplied to the amount of oxygen required for burning the waste W, is set to 1.3.

[0042] [Table 1]

[0043] As shown in Table 1, when the oxygen concentration in the O2-based gas supplied to the oxygen supply line 35 is 80% or higher, the carbon dioxide concentration in the exhaust gas discharged from the wet scrubber 51 and sent to the liquefaction device 120 exceeds 70%, so that the carbon dioxide can be efficiently liquefied in the liquefaction device 120 and the energy consumed for liquefaction can be reduced.

[0044] In the present invention, the oxygen ratio is preferably set to 1.0 or more. Table 2 shows the relationship between the oxygen ratio and the carbon dioxide concentration in the exhaust gas discharged from the wet scrubber 51 when the oxygen concentration in the O2-based gas supplied to the oxygen supply line 35 is set to 90%.

[0045] [Table 2]

[0046] As shown in Table 2, when the oxygen ratio is 1.3 or less, the carbon dioxide concentration in the exhaust gas discharged from the wet scrubber 51 and sent to the liquefaction device 120 exceeds 80%, so that the carbon dioxide can be efficiently liquefied in the liquefaction device 120 and the energy consumed for liquefaction can be reduced.

[0047] Table 3 shows the relationship between the carbon dioxide concentration in the exhaust gas discharged from the wet scrubber 51 and the energy consumption involved in liquefying the carbon dioxide when the oxygen ratio is set to 1.3, and Fig. 2 is a graph showing the relationship in Table 3. The energy consumption is expressed as a relative value when the carbon dioxide concentration is 80% is set to 1.

[0048] [Table 3]

[0049] The energy consumption of the liquefaction device 120 is proportional to the flow rate of the exhaust gas being treated, and if the flow rate of the exhaust gas is constant, the energy consumption does not change even if the carbon dioxide concentration in the exhaust gas changes. In the O2 / CO2 combustion method, if the carbon dioxide concentration in the exhaust gas changes, the exhaust gas flow rate changes, and therefore if the carbon dioxide concentration in the exhaust gas changes, the energy consumption required to liquefy the carbon dioxide also changes.

[0050] Here, we consider the conditions under which the present invention, which uses an O2 / CO2 combustion method, consumes more energy than a conventional air-fired incinerator that supplies air to the grate to liquefy carbon dioxide. For example, if the incinerator uses the conventional air-fired method and the amine method is used to separate and capture carbon dioxide, the estimated energy consumption is 2,216 kW for the amine method separation and capture device, 1,330 kW for the carbon dioxide liquefaction device 120, and 3,546 kW for the carbon dioxide liquefaction.

[0051] If the energy consumption of the oxygen supplier 60 is 949 kW and the energy consumption of the liquefaction device 120 is X, then 949 kW + X < 3546 kW, i.e., X < 2597 kW, then the system of the present invention, which liquefies carbon dioxide using an O2 / CO2 combustion waste incinerator 1, will have an advantage in terms of energy consumption compared to a system that uses the amine method to separate and capture carbon dioxide in a conventional air-fired incinerator.

[0052] Regarding the energy consumption shown in Table 3, when the relative value is 1, the energy consumption of the liquefaction device 120 is 1379 kW. 2597 kW / 1379 kW=1.88, and carbon dioxide concentrations where the value on the vertical axis in the graph of Fig. 2 is less than 1.88 are carbon dioxide concentrations that satisfy X<2597 kW. Therefore, in the range where the carbon dioxide concentration is 45% or more and where the value on the vertical axis is less than 1.88, the present invention has an advantage in terms of energy consumption compared to systems that use the amine method to separate and capture carbon dioxide in a conventional air-fired incinerator.

[0053] Fig. 3 is a graph showing the relationship between the CO2 concentration in the exhaust gas discharged from the wet scrubber 51 and the energy consumption of the entire waste incineration system 1000 when the carbon dioxide concentration is 45% or higher. Note that the energy consumption is expressed as a relative value, with the value when the carbon dioxide concentration is 80% being set to 1. As shown in Fig. 3, compared to when the carbon dioxide concentration is 80%, when the carbon dioxide concentration is 60%, the energy consumption increases by 20%, when the carbon dioxide concentration is 50%, the energy consumption increases by 36%, and when the carbon dioxide concentration is 45%, the energy consumption increases by 46%.

[0054] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be implemented in various other forms. For example, the above-described embodiments may be modified as follows to implement the present invention. The above-described embodiments and the following modifications may be combined with each other. The present invention also includes configurations in which the components of the above-described embodiments and modifications are appropriately combined. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments and modifications, and various modifications are possible.

[0055] In the present invention, the waste incinerator 1 may be a counterflow combustion type incinerator or a double flow type incinerator. [Explanation of symbols]

[0056] 1. Waste incinerator 2. Combustion chamber 4 boilers 21 Flue 22 Drug supply device 23 Dust removal equipment 24 Induced draft fan 51 Wet Scrubber 120 Liquefaction equipment 1000 Waste Incineration System

Claims

1. an incinerator that burns waste while transporting the waste in a combustion chamber having a fire grate; a dust removal means for removing dust from the exhaust gas discharged from the incinerator; a mixed gas supply means for supplying a mixed gas obtained by mixing an oxygen-containing gas with a portion of the exhaust gas from which dust has been removed by the dust removing means to the combustion chamber; a cleaning means for cleaning the exhaust gas from which dust has been removed by the dust removing means; a liquefaction means for directly liquefying the carbon dioxide contained in the exhaust gas cleaned by the cleaning means without passing through a device for separating and capturing the carbon dioxide; A waste incineration system comprising:

2. The concentration of carbon dioxide in the exhaust gas sent from the cleaning means to the liquefaction means is 45% or more.

2. The waste incineration system of claim 1.

3. A waste incineration method for recovering carbon dioxide contained in exhaust gas discharged from an incinerator that burns waste while transporting the waste in a combustion chamber having a fire grate, comprising: Dust is removed from the exhaust gas discharged from the incinerator by dust removal means, supplying a mixed gas obtained by mixing an oxygen-containing gas with a portion of the exhaust gas from which dust has been removed by the dust removing means to the combustion chamber; The exhaust gas from which dust has been removed by the dust removing means is washed by a washing means. The carbon dioxide contained in the exhaust gas cleaned by the cleaning means is directly liquefied by the liquefaction means without going through a device for separating and recovering the carbon dioxide. Waste incineration methods.

Images