A waste gas treatment system and method for sludge drying and carbonization

Abstract

The present invention discloses a waste gas treatment system and method for sludge drying and carbonization, comprising a burner, a secondary combustion chamber, a carbonization device, a drying device, a dust removal device, a heat exchange device, a washing device, a mixing device, an activated carbon adsorption device and a discharge cylinder connected in sequence; the heat exchange device comprises a first heat exchanger and a second heat exchanger connected in parallel; the interior of the carbonization device is connected to the secondary combustion chamber through a heat tracing pipe; the second heat exchanger is connected to any one or more of the burner, the drying device and the mixing device through an air duct; the washing device is connected to the first heat exchanger and the activated carbon adsorption device in sequence; the inlet end of the secondary combustion chamber is connected to the first reagent dosing device; the inlet end of the washing device is connected to the second reagent dosing device. The present invention solves the problems of low pollutant removal efficiency, failure to meet local standards in some areas, affecting the atmospheric environment of residents around the treatment plant, and high operating costs of a single waste gas treatment unit that can be grafted under the prior art.

Description

Technical Field

[0001] The invention relates to the field of waste gas treatment and thermal energy utilization from drying and carbonization, and in particular to a waste gas treatment system and method for sludge drying and carbonization. Background Art

[0002] Sludge drying and carbonization technology is a new technology in the field of sludge treatment and disposal. There are few application cases in China and even in the world. The technology and process are immature, and there are no clear reference emission standards and indicators for the waste gas generated by the system. At present, the waste gas generated by the sludge drying and carbonization process is mainly removed by denitrification, dust removal, and spraying processes. X , particulate matter and sulfur oxides, etc. The waste gas indicators after treatment can meet most of the national standards. However, with the improvement of environmental protection requirements and the strengthening of public environmental awareness, in order to reduce or completely eliminate the impact of odor and other pollutants on residents around the disposal plant, some regions have formulated local waste gas emission standards that are stricter than national standards, including NO X , particulate matter, odor concentration, etc. The current waste gas treatment process cannot meet the above pollutant emission standards. It is urgent to develop efficient waste gas purification technology for drying and carbonization, and at the same time consider the waste gas treatment cost to achieve the goal of efficient waste gas treatment under low consumption conditions.

[0003] To this end, we propose a waste gas treatment system and method for sludge drying and carbonization to solve the above problems. Summary of the invention

[0004] In order to solve the problem of low pollutant removal efficiency in sludge drying and carbonization waste gas treatment under existing technologies, which cannot meet local standards in some areas and affect the atmospheric environment of residents around the treatment plant, the high operating cost of the grafted single waste gas treatment unit.

[0005] The present invention provides the following technical solution: a waste gas treatment system for sludge drying and carbonization, comprising:

[0006] A burner, a secondary combustion chamber, a carbonization device, a drying device, a dust removal device, a heat exchange device, a washing device, a mixing device, an activated carbon adsorption device and a discharge cylinder connected in sequence;

[0007] The heat exchange device comprises a first heat exchange device and a second heat exchanger connected in parallel;

[0008] The first heat exchanger includes a high-temperature exhaust gas channel and a low-temperature exhaust gas channel, and the second heat exchanger includes a high-temperature exhaust gas channel and an air channel;

[0009] The interior of the carbonization device is connected to the secondary combustion chamber via a heating pipe;

[0010] The low-temperature exhaust gas channel of the first heat exchanger is connected to the outlet of the scrubbing device and the activated carbon adsorption device;

[0011] The air channel of the second heat exchanger is in communication with any one or more of an air input pipeline, a burner, a drying device, and a mixing device;

[0012] The inlet end of the secondary combustion chamber is connected to the first reagent dosing device;

[0013] The inlet end of the washing device is connected to the second reagent dosing device.

[0014] Preferably, the dust removal device adopts any one or more combinations of bag dust collector, cyclone dust collector and electrostatic precipitator.

[0015] Preferably, the first heat exchanger and the second heat exchanger are air heat exchangers, and the high-temperature exhaust gas channel of the air heat exchanger is connected to the inlet of the washing device.

[0016] Preferably, the second heat exchanger is connected to the burner and the drying device through a first air duct, and is connected to the mixing device through a second air duct.

[0017] Preferably, the first heat exchanger is connected to the outlet of the washing device and the activated carbon adsorption device respectively through a third air duct and a fourth air duct.

[0018] Preferably, the second agent dosing device comprises an agent preparation device and a dosing device, and the agent is one or both of an acidic agent and an alkaline agent.

[0019] Preferably, the washing device is a spray tower, which includes a spray pipe and a nozzle. The outlet of the second agent dosing device is connected to the spray pipe. The agent is mixed with spray water through the spray pipe and then sprayed out from the nozzle to react with the exhaust gas.

[0020] Preferably, the first reagent dosing device includes a reagent preparation device and a dosing device; the outlet of the first reagent dosing device is connected to the secondary combustion chamber, and a nozzle is arranged in the secondary combustion chamber, and the reagent is sprayed into the secondary combustion chamber from the nozzle through a pipeline.

[0021] Preferably, the carbonization device includes a jacket and a furnace body, the secondary combustion chamber is connected to the jacket, the flue gas from the secondary combustion chamber enters the jacket for indirect heat exchange with the sludge; the pyrolysis gas and tar generated by the pyrolysis of the sludge in the furnace body enter the secondary combustion chamber through the heating pipe and burn.

[0022] Preferably, the outlet of the activated carbon adsorption device is connected to a centrifugal fan, and the exhaust port of the centrifugal fan is connected to a discharge cylinder.

[0023] A method for treating waste gas for sludge drying and carbonization comprises the following steps:

[0024] S1: The hot flue gas generated by the burner is directly introduced into the secondary combustion chamber, and the pyrolysis gas generated by the pyrolysis of the sludge in the carbonization device is introduced into the secondary combustion chamber through the heat tracing pipe for full combustion, and together they serve as a supplementary heat source for sludge drying and carbonization;

[0025] S2: The hot flue gas in the secondary combustion chamber is introduced into the jacket of the carbonization device and indirectly exchanges heat with the sludge. At the same time, urea is sprayed into the secondary combustion chamber by the first reagent dosing device, and the nitrogen oxides in the hot flue gas are removed by the SNCR method;

[0026] S3: The hot flue gas at the outlet of the carbonization device jacket is introduced into the drying device and directly exchanges heat with the sludge;

[0027] S4: The exhaust gas outlet of the drying device is connected to the cyclone dust collector and the bag dust collector in turn, and the exhaust gas is introduced into the cyclone dust collector and the bag dust collector in turn to reduce the particulate matter in the exhaust gas;

[0028] S5: The outlet of the bag filter is connected to one or both of the first heat exchanger and the second heat exchanger. The waste gas after heat exchange enters the scrubbing device through the high-temperature waste gas channel, and NaOH and sulfuric acid are added respectively through the second reagent dosing device to adsorb and degrade NH3 and H2S pollutants in the waste gas;

[0029] S5.1: When the second heat exchanger is used alone, the air exchanges heat with the high-temperature exhaust gas and flows to the mixing device, the secondary combustion chamber, and the drying device through the second air duct and the first air duct respectively; the exhaust gas washed and cooled by the washing device also flows to the mixing device, and the hot air in the air channel is mixed with the washed exhaust gas in the mixing device, and the mixed exhaust gas flows to the activated carbon adsorption device;

[0030] S5.2: When the first heat exchanger is used, the exhaust gas at the outlet of the scrubbing device is directly introduced into the low-temperature exhaust gas channel of the first heat exchanger through the third air duct for heat exchange with the exhaust gas in the high-temperature exhaust gas channel. The exhaust gas after heat exchange flows to the activated carbon adsorption device through the fourth air duct.

[0031] S6: After the waste gas is treated in S5, the temperature rises, the saturated humidity increases, and the waste gas is introduced into the activated carbon adsorption device. At this time, the waste gas is in an unsaturated state. The activated carbon adsorption device (90) adsorbs VOC, H2S, NH3 odor gases in the waste gas, and can also adsorb trace amounts of dioxins in the waste gas;

[0032] S7: The outlet of the activated carbon adsorption device is connected to the discharge cylinder.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention solves the problems of low pollutant removal efficiency, inability to meet local standards in some areas, affecting the atmospheric environment of residents around the treatment plant, and high operating costs of a single waste gas treatment unit that can be grafted under the prior art. The present invention adopts SNCR, dust removal, heat exchange, washing, and activated carbon adsorption processes to treat sludge drying and carbonization waste gas. In the process, the system energy is fully utilized through pyrolysis gas incineration, hot waste gas heat exchange and recycling, thereby achieving the goal of efficient waste gas purification under low energy consumption conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the exhaust gas treatment system in the present invention;

[0035] Figure 2 This is a system schematic diagram of Example 1 of the present invention;

[0036] Figure 3 This is a system schematic diagram of Example 2 of the present invention;

[0037] In the figure: a burner 10, a secondary combustion chamber 20, a carbonization device 30, a heating pipe 31, a drying device 40, a dust removal device 50, a first heat exchanger 61, a second heat exchanger 62, a first air duct 601, a second air duct 602, a third air duct 603, a fourth air duct 604, a washing device 70, a mixing device 80, an activated carbon adsorption device 90, a discharge cylinder 100, a first agent dosing device 111, and a second agent dosing device 112. DETAILED DESCRIPTION

[0038] The following will be combined with the attached embodiment of the present invention Figure 1-3 , the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0039] See also Figure 2 The present invention provides a technical solution: a waste gas treatment system for sludge drying and carbonization, comprising:

[0040] A burner 10, a secondary combustion chamber 20, a carbonization device 30, a drying device 40, a dust removal device 50, a second heat exchanger 62, a washing device 70, a mixing device 80, an activated carbon adsorption device 90 and a discharge cylinder 100 connected in sequence;

[0041] The second heat exchanger 62 includes a high temperature exhaust gas passage and an air passage;

[0042] The second heat exchanger 62 is connected to any one or more of the burner 10, the drying device 40, and the mixing device 80 through the first air duct 601 and the second air duct 602;

[0043] The interior of the carbonization device 30 is connected to the secondary combustion chamber 20 via a heat tracing pipe 31;

[0044] The inlet end of the second combustion chamber 20 is connected to the first reagent dosing device 111;

[0045] The inlet end of the washing device 70 is connected to the second reagent dosing device 112 .

[0046] Furthermore, the dust removal device 50 adopts any one or more combinations of bag dust collector, cyclone dust collector and electric dust collector.

[0047] Furthermore, the second heat exchanger 62 is an air heat exchanger, and the high-temperature exhaust gas channel of the air heat exchanger is connected to the inlet of the scrubbing device 70 .

[0048] Furthermore, the air heat exchanger is connected to the burner 10 and the drying device 40 through the first air duct 601 , and the heat exchange device 60 is connected to the mixing device 80 through the second air duct 602 .

[0049] The heated air in the air passage of the air heat exchanger is collected and then transmitted to the burner 10 , the drying device 40 , and the mixing device 80 , respectively.

[0050] Furthermore, the second agent dosing device 112 includes an agent preparation device and an agent dosing device, and the agent is one or both of an acidic agent and an alkaline agent.

[0051] Furthermore, the washing device 70 is a spray tower, which includes a spray pipe and a nozzle. The outlet of the second reagent dosing device 112 is connected to the spray pipe. The reagent is mixed with the spray water through the spray pipe and then sprayed out from the nozzle to react with the exhaust gas.

[0052] Furthermore, the first reagent dosing device 111 includes a reagent preparation device and a dosing device; the outlet of the first reagent dosing device 111 is connected to the secondary combustion chamber 20, and a nozzle is arranged in the secondary combustion chamber 20, and the reagent is sprayed into the secondary combustion chamber 20 through the pipeline from the nozzle.

[0053] Furthermore, the carbonization device 30 includes a jacket and a furnace body, the secondary combustion chamber 20 is connected to the jacket, and the flue gas from the secondary combustion chamber 20 passes into the jacket for indirect heat exchange with the sludge; the pyrolysis gas and tar generated by the pyrolysis of the sludge in the furnace body enter the secondary combustion chamber 20 through the heating pipe 31 and burn.

[0054] Furthermore, the outlet of the activated carbon adsorption device 90 is connected to the centrifugal fan, and the exhaust port of the centrifugal fan is connected to the discharge cylinder 100 .

[0055] Based on the above-mentioned exhaust gas treatment system, the exhaust gas treatment method specifically includes the following steps:

[0056] S1: The hot flue gas generated by the burner 10 is directly introduced into the secondary combustion chamber 20, and the pyrolysis gas generated by the pyrolysis of the sludge in the carbonization device 30 is introduced into the secondary combustion chamber 20 through the heat tracing pipe 31 for full combustion, and together they serve as a supplementary heat source for sludge drying and carbonization;

[0057] S2: The hot flue gas with a temperature greater than 850° C. in the secondary combustion chamber 20 is introduced into the jacket of the carbonization device 30 and indirectly exchanges heat with the sludge. At the same time, urea is sprayed into the secondary combustion chamber 20 by the first reagent dosing device 111 to remove nitrogen oxides in the hot flue gas by the SNCR method;

[0058] S3: The hot flue gas with a temperature of 400°C at the outlet of the jacket of the carbonization device 30 is introduced into the drying device 40 and directly exchanges heat with the sludge;

[0059] S4: The exhaust gas outlet of the drying device 40 is connected to the cyclone dust collector and the bag dust collector in sequence, and the exhaust gas with a temperature of 250°C is introduced into the cyclone dust collector and the bag dust collector in sequence to reduce particulate matter in the exhaust gas;

[0060] S5: The outlet temperature of the bag filter is 220°C and is connected to the high-temperature exhaust gas channel of the second heat exchanger 62, exchanging heat with the cold air in the air channel to reduce the exhaust gas temperature to 100°C.

[0061] S6: The exhaust gas channel of the second heat exchanger is connected to the scrubbing device, and the exhaust gas enters the spray scrubbing tower. NaOH and sulfuric acid are added respectively through the second reagent dosing device 112 to adsorb and degrade NH3 and H2S pollutants in the exhaust gas; the air heated by the air heat exchanger and at a temperature of 90°C is collected and introduced into the mixing box;

[0062] S7: The outlet temperature of the air channel is heated to 90°C and introduced into the mixing device 80; at the same time, the outlet of the spray tower is connected to the mixing device 80, and the waste gas with a temperature of 50°C after spraying is mixed with the air heated by the air heat exchanger in the mixing device 80;

[0063] S8: The temperature of the mixed exhaust gas is 80°C, and its saturated humidity increases. The exhaust gas is introduced into the activated carbon adsorption device 90. At this time, the exhaust gas with a temperature greater than 50°C is in an unsaturated state. The activated carbon adsorption device 90 adsorbs VOC, H2S, NH3 odor gases in the exhaust gas, and can also adsorb trace amounts of dioxins in the exhaust gas;

[0064] S9: The outlet of the activated carbon adsorption device 90 is connected to the discharge cylinder 100 .

[0065] After the drying and carbonization waste gas is treated by the above-mentioned SNCR, dust removal, washing, activated carbon adsorption treatment system and method, NO X, particulate matter, hydrogen sulfide, ammonia, VOC, odor concentration, dioxins and other indicators are effectively controlled. In the process, the system energy is fully utilized through pyrolysis gas incineration, hot exhaust gas heat exchange and recycling, achieving the goal of efficient exhaust gas purification under low energy consumption conditions. Example 2

[0066] See also Figure 3 The present invention provides a technical solution: a waste gas treatment system for sludge drying and carbonization, comprising:

[0067] A burner 10, a secondary combustion chamber 20, a carbonization device 30, a drying device 40, a dust removal device 50, a heat exchange device, a washing device 70, a mixing device 80, an activated carbon adsorption device 90 and a discharge cylinder 100 connected in sequence;

[0068] The heat exchange device comprises a first heat exchanger 61 and a second heat exchanger 62 connected in parallel;

[0069] The first heat exchanger 61 includes a high-temperature exhaust gas passage and a low-temperature exhaust gas passage, and the second heat exchanger 62 includes a high-temperature exhaust gas passage and an air passage;

[0070] The low-temperature exhaust gas passage of the first heat exchanger 61 is connected to the outlet of the scrubbing device 70 and the activated carbon adsorption device 90;

[0071] The air passage of the second heat exchanger 62 is connected to any one or two of the air input pipe, the burner 10, and the drying device 40;

[0072] The interior of the carbonization device 30 is connected to the secondary combustion chamber 20 via a heat tracing pipe 31;

[0073] The inlet end of the second combustion chamber 20 is connected to the first reagent dosing device 111;

[0074] The inlet end of the washing device 70 is connected to the second reagent dosing device 112 .

[0075] Furthermore, the dust removal device 50 adopts any one or more combinations of bag dust collector, cyclone dust collector and electric dust collector.

[0076] Furthermore, the first heat exchanger 61 and the second heat exchanger 62 are air heat exchangers, and the high-temperature exhaust gas channel of the air heat exchanger is connected to the inlet of the washing device 70.

[0077] Furthermore, the second heat exchanger 62 is connected to the burner 10 and the drying device 40 through the first air duct 601 .

[0078] Furthermore, the first heat exchanger 61 is connected to the outlet of the washing device 70 and the activated carbon adsorption device 90 through the third air duct 603 and the fourth air duct 604 respectively.

[0079] Furthermore, the second agent dosing device 112 includes an agent preparation device and an agent dosing device, and the agent is one or both of an acidic agent and an alkaline agent.

[0080] Furthermore, the washing device 70 is a spray tower, which includes a spray pipe and a nozzle. The outlet of the second reagent dosing device 112 is connected to the spray pipe. The reagent is mixed with the spray water through the spray pipe and then sprayed out from the nozzle to react with the exhaust gas.

[0081] Furthermore, the first reagent dosing device 111 includes a reagent preparation device and a dosing device; the outlet of the first reagent dosing device 111 is connected to the secondary combustion chamber 20, and a nozzle is arranged in the secondary combustion chamber 20, and the reagent is sprayed into the secondary combustion chamber 20 through the pipeline from the nozzle.

[0082] Furthermore, the carbonization device 30 includes a jacket and a furnace body, the secondary combustion chamber 20 is connected to the jacket, and the flue gas from the secondary combustion chamber 20 passes into the jacket for indirect heat exchange with the sludge; the pyrolysis gas and tar generated by the pyrolysis of the sludge in the furnace body enter the secondary combustion chamber 20 through the heating pipe 31 and burn.

[0083] Furthermore, the outlet of the activated carbon adsorption device 90 is connected to the centrifugal fan, and the exhaust port of the centrifugal fan is connected to the discharge cylinder 100 .

[0084] Based on the above-mentioned exhaust gas treatment system, the exhaust gas treatment method specifically includes the following steps:

[0085] S1: The hot flue gas generated by the burner 10 is directly introduced into the secondary combustion chamber 20, and the pyrolysis gas generated by the pyrolysis of the sludge in the carbonization device 30 is introduced into the secondary combustion chamber 20 through the heat tracing pipe 31 for full combustion, and together they serve as a supplementary heat source for sludge drying and carbonization;

[0086] S2: The hot flue gas with a temperature greater than 850° C. in the secondary combustion chamber 20 is introduced into the jacket of the carbonization device 30 and indirectly exchanges heat with the sludge. At the same time, urea is sprayed into the secondary combustion chamber 20 by the first reagent dosing device 111 to remove nitrogen oxides in the hot flue gas by the SNCR method;

[0087] S3: The hot flue gas with a temperature of 400°C at the outlet of the jacket of the carbonization device 30 is introduced into the drying device 40 and directly exchanges heat with the sludge;

[0088] S4: The exhaust gas outlet of the drying device 40 is connected to the cyclone dust collector and the bag dust collector in sequence, and the exhaust gas is introduced into the cyclone dust collector and the bag dust collector in sequence to reduce particulate matter in the exhaust gas;

[0089] S5: The outlet of the bag filter is connected to the first heat exchanger 61 and the second heat exchanger 62. The exhaust gas after heat exchange enters the washing device 70 through the high-temperature exhaust gas channel, and NaOH and sulfuric acid are added respectively through the second reagent dosing device 112 to adsorb and degrade NH3 and H2S pollutants in the exhaust gas.

[0090] In the second heat exchanger 62, after the air exchanges heat with the high-temperature exhaust gas, it flows through the second air duct 602, the first air duct 601, the secondary combustion chamber 20, and the drying device 40 respectively, serving as a supplementary heat source for combustion and drying.

[0091] The exhaust gas at the outlet of the scrubbing device 70 is directly introduced into the low-temperature exhaust gas channel of the first heat exchanger 61 through the third air duct 603 for heat exchange with the exhaust gas in the high-temperature exhaust gas channel.

[0092] S6: After the heat exchange, the exhaust gas temperature rises, the saturated humidity increases, and the exhaust gas flows to the activated carbon adsorption device through the fourth air duct 604 to adsorb the VOC, H2S, NH3 odorous gases in the exhaust gas, and can also adsorb trace amounts of dioxins in the exhaust gas;

[0093] S7: The outlet of the activated carbon adsorption device 90 is connected to the discharge cylinder 100 .

[0094] After the drying and carbonization waste gas is treated by the above-mentioned SNCR, dust removal, washing, activated carbon adsorption treatment system and method, indicators such as NOX, particulate matter, hydrogen sulfide, ammonia, VOC, odor concentration, dioxin, etc. are effectively controlled. In the process, the system energy is fully utilized through pyrolysis gas incineration, hot waste gas heat exchange and recycling. At the same time, no fresh air is introduced in the waste gas treatment process, achieving the goal of efficient waste gas purification under low energy consumption conditions.

[0095] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A waste gas treatment system for sludge drying and carbonization, characterized in that: include: A burner (10), a secondary combustion chamber (20), a carbonization device (30), a drying device (40), a dust removal device (50), a heat exchange device, a washing device (70), a mixing device (80), an activated carbon adsorption device (90), and a discharge cylinder (100) connected in sequence; The heat exchange device comprises a first heat exchanger (61) and a second heat exchanger (62) connected in parallel; The first heat exchanger (61) comprises a high-temperature exhaust gas channel and a low-temperature exhaust gas channel, and the second heat exchanger (62) comprises a high-temperature exhaust gas channel and an air channel; The interior of the carbonization device (30) is connected to the secondary combustion chamber (20) via a heating pipe (31); The low-temperature exhaust gas channel of the first heat exchanger (61) is in communication with the outlet of the scrubbing device (70) and the activated carbon adsorption device (90); The air passage of the second heat exchanger (62) is in communication with any one or more of the air input pipeline, the burner (10), the drying device (40), and the mixing device (80); The inlet end of the secondary combustion chamber (20) is connected to the first reagent dosing device (111); The inlet end of the washing device (70) is connected to the second reagent dosing device (112).

2. A waste gas treatment system for sludge drying and carbonization according to claim 1, characterized in that: The dust removal device (50) adopts any one or more combinations of a bag dust collector, a cyclone dust collector, and an electric dust collector.

3. The waste gas treatment system for sludge drying and carbonization according to claim 1 is characterized by: The first heat exchanger (61) and the second heat exchanger (62) are air heat exchangers, and the high-temperature exhaust gas passage of the air heat exchanger is in communication with the inlet of the scrubbing device (70).

4. A waste gas treatment system for sludge drying and carbonization according to claim 3, characterized in that: The second heat exchanger (62) is connected to the burner (10) and the drying device (40) via the first air duct (601), and is connected to the mixing device (80) via the second air duct (602).

5. The waste gas treatment system for sludge drying and carbonization according to claim 3 is characterized by: The first heat exchanger (61) is connected to the outlet of the washing device (70) via a third air duct (603), and is connected to the activated carbon adsorption device (90) via a fourth air duct (604).

6. The waste gas treatment system for sludge drying and carbonization according to claim 1 is characterized by: The second agent dosing device (112) comprises an agent preparation device and an agent dosing device, and the agent is one or both of an acidic agent and an alkaline agent.

7. A waste gas treatment system for sludge drying and carbonization according to claim 6, characterized in that: The washing device (70) is a spray tower, comprising a spray pipe and a nozzle, the outlet of the second reagent dosing device (112) is connected to the spray pipe, the reagent is mixed with spray water through the spray pipe and then sprayed out from the nozzle to react with the exhaust gas.

8. The waste gas treatment system for sludge drying and carbonization according to claim 1, characterized in that: The first agent dosing device (111) comprises an agent preparation device and a dosing device; an outlet of the first agent dosing device (111) is connected to the secondary combustion chamber (20), and a nozzle is arranged in the secondary combustion chamber (20), and the agent is sprayed into the secondary combustion chamber (20) through the pipeline from the nozzle.

9. The waste gas treatment system for sludge drying and carbonization according to claim 1, characterized in that: The carbonization device (30) comprises a jacket and a furnace body, the secondary combustion chamber (20) is connected to the jacket, and the flue gas of the secondary combustion chamber (20) is passed into the jacket to indirectly exchange heat with the sludge; the pyrolysis gas and tar generated by the sludge being pyrolyzed in the furnace body enter the secondary combustion chamber (20) through the heating pipe (31) and are burned.

10. The waste gas treatment system for sludge drying and carbonization according to claim 1, characterized in that: The outlet of the activated carbon adsorption device (90) is connected to a centrifugal fan, and the exhaust port of the centrifugal fan is connected to a discharge cylinder (100).

11. A method for treating waste gas for sludge drying and carbonization, characterized in that: The exhaust gas treatment system according to any one of claims 1 to 10 comprises the following steps: S1: The hot flue gas generated by the combustion of the burner (10) is directly introduced into the secondary combustion chamber (20), and the pyrolysis gas generated by the pyrolysis of the sludge in the carbonization device (30) is introduced into the secondary combustion chamber (20) through the heat tracing pipe (31) for full combustion, and together they serve as a supplementary heat source for sludge drying and carbonization; S2: The hot flue gas in the secondary combustion chamber (20) is introduced into the jacket of the carbonization device (30) and indirectly exchanges heat with the sludge, and at the same time, urea is sprayed into the secondary combustion chamber (20) by the first reagent dosing device (111) to remove nitrogen oxides in the hot flue gas by using the SNCR method; S3: The hot flue gas at the outlet of the jacket of the carbonization device (30) is introduced into the drying device (40) and directly exchanges heat with the sludge; S4: the exhaust gas outlet of the drying device (40) is connected to the cyclone dust collector and the bag dust collector in sequence, and the exhaust gas is introduced into the cyclone dust collector and the bag dust collector in sequence to reduce particulate matter in the exhaust gas; S5: The outlet of the bag filter is connected to one or both of the first heat exchanger (61) and the second heat exchanger (62). The waste gas after heat exchange enters the scrubbing device (70) through the high-temperature waste gas channel, and NaOH and sulfuric acid are added respectively through the second reagent dosing device (112) to adsorb and degrade NH 3、 H2S pollutants; S5.1: When the second heat exchanger (62) is used alone, the air exchanges heat with the high-temperature exhaust gas and flows through the second air duct (602) and the first air duct (601) to the mixing device (80), the secondary combustion chamber (20), and the drying device (40); the exhaust gas washed and cooled by the washing device (70) also flows to the mixing device (80), the hot air in the air passage and the washed exhaust gas are mixed in the mixing device (80), and the mixed exhaust gas flows to the activated carbon adsorption device (90); S5.2: When the first heat exchanger (61) is used, the exhaust gas at the outlet of the scrubbing device (70) is directly introduced into the low-temperature exhaust gas channel of the first heat exchanger (61) through the third air duct (603) for heat exchange with the exhaust gas in the high-temperature exhaust gas channel, and the exhaust gas after heat exchange flows to the activated carbon adsorption device (90) through the fourth air duct (604); S6: After the waste gas is treated in S5, the temperature rises and the saturated humidity increases, and the waste gas is introduced into the activated carbon adsorption device (90). At this time, the waste gas is in an unsaturated state. The activated carbon adsorption device (90) adsorbs VOC, H2S, NH3 odor gases in the waste gas, and can also adsorb trace amounts of dioxins in the waste gas; S7: The outlet of the activated carbon adsorption device (90) is connected to the discharge cylinder (100).

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