A method and system for low-temperature pyrolysis of municipal sludge

Abstract

The invention discloses a method and system for low-temperature pyrolysis of municipal sludge. A magnetic field is used to constrain plasma gas, so that the plasma gas in a mixing device is kept at 1 cm to 2 cm away from the inner wall of a mixing container, and the plasma gas in an electric heating device is kept at 1 cm to 2 cm away from the radial inner side of a heating coil, so as to prevent the plasma in the plasma gas from being adsorbed by the metal conductor on the inner wall of the container, thereby ensuring that the plasma gas and the sludge can be fully mixed and reacted, thereby utilizing the energy of the plasma to break the chemical bonds of organic compounds in the sludge, so that the sludge pyrolysis can be carried out in a relatively low temperature environment, thereby reducing energy consumption, reducing the difficulty of temperature control, and extending the service life of the equipment. At the same time, the problem of various impurities in the sludge being decomposed at high temperature to produce dioxins is solved, so as to achieve the purpose of energy saving and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge pyrolysis treatment, and in particular relates to a municipal sludge low-temperature pyrolysis method and a system thereof. Background Art

[0002] With the increasing population and the increasing urbanization of the global society, sewage treatment plants will discharge a large amount of sludge every day. Sludge contains a large amount of organic matter and rich nutrients such as nitrogen and phosphorus. If it is discharged into the water body at will, it will consume a lot of oxygen in the water body, causing the water quality to deteriorate and seriously affecting the survival of aquatic organisms; the nutrients in the sludge will make the water body rich in oxygen, and algae will multiply in large numbers, thus deteriorating the water quality; in addition, there are a variety of toxic substances, heavy metals, pathogenic bacteria, parasite eggs and other harmful substances in the sludge. If they are not properly handled and disposed of, they will spread diseases, pollute soil and crops, and be transferred to humans through the food chain. If the sludge generated by sewage treatment plants every day is not properly handled and disposed of and arbitrarily discharged and piled up, it will cause serious secondary pollution to water sources, soil and the surrounding environment, making it impossible for the built sewage treatment plants to fully play their role in eliminating environmental pollution. It is urgent to solve the problem of sewage sludge.

[0003] Sludge pyrolysis is a process that utilizes the thermal instability of organic matter in sludge and uses heat energy to break the chemical bonds of organic compounds in sludge under oxygen-deficient conditions, thereby converting large-molecule organic matter into small-molecule combustible gas and solid residue. However, existing sludge pyrolysis methods generally have the following disadvantages:

[0004] (1) High energy consumption. The traditional type uses high-temperature oxidation combustion at 800℃ to 1000℃, which has high energy consumption, complex control, and serious equipment aging.

[0005] (2) The pollutant content is high. The traditional high-temperature oxidation combustion at 800℃ to 1000℃ produces dioxins from the high-temperature decomposition of various impurities in the sludge, which poses a high environmental risk. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a municipal sludge low-temperature pyrolysis method and system thereof that is energy-saving and environmentally friendly, has low temperature control difficulty, and has a long equipment life.

[0007] In order to solve the above technical problems, one aspect of the present invention provides a method for low-temperature pyrolysis of municipal sludge, which comprises the following steps:

[0008] S1. Supply sludge into the mixing device;

[0009] S2. Plasma gas is injected into the mixing device, and the plasma gas in the mixing device is kept at a distance of 1 cm to 2 cm from the inner wall of the mixing container by using a magnetic field, and the mixing container is driven to rotate so that the sludge and the plasma gas are fully mixed;

[0010] S3. The sludge mixture treated in step S2 is transported to an electric heating device;

[0011] S4. Turn on the power of the heating coil in the electric heating device, the heating coil is located 1 cm to 30 cm away from the inner wall of the heating container, so that the temperature of the metal conductor of the wall of the heating container and the sludge mixture is controlled not to exceed 500°C, and the plasma gas in the electric heating device is kept at 1 cm to 2 cm radially inward from the heating coil by using a magnetic field, and the heating container is driven to rotate at the same time, so that the sludge and the plasma gas are fully mixed and reacted, and the energy of the plasma is used to break the chemical bonds of the organic compounds in the sludge;

[0012] S5. The sludge mixture treated in step S4 is transported to a sedimentation device;

[0013] S6. The sedimentation device provides an anaerobic environment for the sludge mixture and performs sedimentation treatment to promote the decomposition of the sludge mixture into gas, water and inorganic ash in an anaerobic state.

[0014] As a preferred solution of the above-mentioned municipal sludge low-temperature pyrolysis method, in the step S1, it is required that the sludge cannot fill up the mixing device, and the volume percentage of the sludge in the mixing container is 70-90%.

[0015] As a preferred embodiment of the above-mentioned municipal sludge low-temperature pyrolysis method, in step S2, the specific steps of driving the mixing container to rotate are: first rotating for 15 minutes to 30 minutes, then standing for 10 minutes to 20 minutes, and rotating again for 15 minutes to 30 minutes.

[0016] As a preferred embodiment of the above-mentioned municipal sludge low-temperature pyrolysis method, in step S4, the heating coil is heated in a segmented heating manner: in the first stage, the temperature of the metal conductor of the wall of the heating container and the sludge mixture is increased to 100°C within 10 minutes; in the second stage, the temperature is kept warm for 5 to 10 minutes; in the third stage, the temperature of the metal conductor of the wall of the heating container and the sludge mixture is increased to 300°C within 10 minutes; in the fourth stage, the temperature is kept warm for 5 to 10 minutes; in the fifth stage, the temperature of the metal conductor of the wall of the heating container and the sludge mixture is increased to 450°C within 10 minutes.

[0017] Another aspect of the present invention provides a municipal sludge low-temperature pyrolysis system, which includes a mixing device, an electric heating device and a precipitation device connected in sequence, the mixing device includes a mixing container, a first magnetic strip and a first rotating drive mechanism for driving the mixing container to rotate, the mixing container is provided with a sludge inlet and a plasma inlet, the first magnetic strip is provided in plurality and is evenly distributed on the outer wall of the mixing container along the circumferential direction of the mixing container; the first magnetic strip generates a magnetic field to keep the plasma gas in the mixing container at a distance of 1 cm to 2 cm from the inner wall of the mixing container; the electric heating device includes a heating container, a second magnetic strip, a heating coil and a second rotating drive mechanism for driving the heating container to rotate, the heating coil is provided in plurality and is evenly distributed in the heating container along the circumferential direction of the heating container and is located at a distance of 1 cm to 30 cm from the inner wall of the heating container; the second magnetic strip is provided in plurality and is evenly distributed on the outer wall of the heating container along the circumferential direction of the heating container; the second magnetic strip generates a magnetic field to compress the plasma gas in the mixing container and keep it at a distance of 1 cm to 2 cm from the radial inner side of the heating coil.

[0018] As a preferred embodiment of the above-mentioned municipal sludge low-temperature pyrolysis system, the sludge outlet of the mixing container is connected to the sludge inlet of the heating container through a first conveying pipe, and the first conveying pipe is provided with a first conveying pump and a first valve; the sludge outlet of the heating container is connected to the sedimentation device through a second conveying pipe, and the second conveying pipe is provided with a second conveying pump and a second valve.

[0019] As a preferred embodiment of the above-mentioned municipal sludge low-temperature pyrolysis system, the main body of the precipitation device is a sealed container, and the precipitation device is provided with a vacuum pump capable of discharging air in the sealed container and forming an oxygen-deficient environment.

[0020] As a preferred embodiment of the above-mentioned municipal sludge low-temperature pyrolysis system, the first rotary drive mechanism includes a first motor, a first reduction gear, a first transmission shaft, a first driving gear and a first driven gear, the power output end of the first motor is connected to the first transmission shaft through the first reduction gear, the first driving gear is fixedly sleeved on the first transmission shaft, the first driven gear is fixed on the outer circumferential wall of the mixing container and is coaxial with the rotation axis of the mixing container, and the first driving gear is meshed with the first driven gear; the first rotary drive mechanism also includes a plurality of first guide wheel groups, among which at least one first guide wheel group is against the bottom of the mixing container, at least one first guide wheel group is against the side of the mixing container, and at least one first guide wheel group is against the other side of the mixing container.

[0021] As a preferred embodiment of the above-mentioned municipal sludge low-temperature pyrolysis system, the second rotary drive mechanism includes a second motor, a second reduction gear, a second transmission shaft, a second driving gear and a second driven gear, the power output end of the second motor is connected to the second transmission shaft through the second reduction gear, the second driving gear is fixedly sleeved on the second transmission shaft, the second driven gear is fixed on the outer circumferential wall of the heating container and is coaxial with the rotation axis of the heating container, and the second driving gear is meshed with the second driven gear; the second rotary drive mechanism also includes a plurality of second guide wheel groups, among which at least one second guide wheel group is against the bottom of the heating container, at least one second guide wheel group is against the side of the heating container, and at least one second guide wheel group is against the other side of the heating container.

[0022] As a preferred embodiment of the above-mentioned municipal sludge low-temperature pyrolysis system, a stirring rod is provided in the mixing container.

[0023] The low-temperature pyrolysis method and system of municipal sludge provided by the present invention have the following beneficial effects compared with the prior art:

[0024] The present invention utilizes a magnetic field to constrain plasma gas, so that the plasma gas in the mixing device is maintained at 1 cm to 2 cm away from the inner wall of the mixing container, and the plasma gas in the electric heating device is maintained at 1 cm to 2 cm away from the radial inner side of the heating coil, so as to prevent the plasma in the plasma gas from being adsorbed by the metal conductor on the inner wall of the container, thereby ensuring that the plasma gas and the sludge can be fully mixed and reacted, thereby utilizing the energy of the plasma to break the chemical bonds of the organic compounds in the sludge, so that the sludge pyrolysis can be carried out in a relatively low temperature environment, thereby reducing energy consumption, reducing the difficulty of temperature control, and extending the service life of the equipment, and at the same time solving the problem of various impurities in the sludge decomposing at high temperature to produce dioxins, so as to achieve the purpose of energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings of the embodiment are briefly introduced below.

[0026] Figure 1 This is a front view of a municipal sludge low-temperature pyrolysis system provided by the present invention;

[0027] Figure 2 is a side view of the first rotary drive mechanism;

[0028] Figure 3 is a side view of the second rotation drive mechanism.

[0029] Markings in the figure:

[0030] Mixing device 100, mixing container 101, first magnetic strip 102, sludge inlet 103, plasma inlet 104, first motor 105, first reduction box 106, first transmission shaft 107, first driving gear 108, first driven gear 109, first guide wheel set 110, stirring rod 111;

[0031] Electric heating device 200, heating container 201, heating coil 202, second magnetic strip 203, second motor 204, second reduction box 205, second transmission shaft 206, second driving gear 207, second driven gear 208, second guide wheel set 209;

[0032] Sedimentation device 300, vacuum pump 301;

[0033] A first delivery pipeline 400, a first delivery pump 401, and a first valve 402;

[0034] A second delivery pipeline 500 , a second delivery pump 501 , and a second valve 502 . DETAILED DESCRIPTION

[0035] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0036] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. It should be understood that the terms "first", "second", etc. are used in the present invention to describe various information, but such information should not be limited to these terms, which are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0037] like Figure 1 As shown, a preferred embodiment of the present invention provides a method for low-temperature pyrolysis of municipal sludge, which comprises the following steps:

[0038] S1. Supplying sludge to the mixing device 100;

[0039] S2. Plasma gas is injected into the mixing device 100, and the plasma gas in the mixing device 100 is kept at a distance of 1 cm to 2 cm from the inner wall of the mixing container 101 by using a magnetic field, and the mixing container 101 is driven to rotate so that the sludge and the plasma gas are fully mixed; wherein the plasma gas comes from a plasma generator;

[0040] S3. The sludge mixture treated in step S2 is transported to an electric heating device;

[0041] S4. Turn on the power of the heating coil 202 in the electric heating device 200, the heating coil 202 is located 1 cm to 30 cm away from the inner wall of the heating container 201, so that the temperature of the metal conductor of the wall of the heating container 201 and the sludge mixture is controlled not to exceed 500°C, and the plasma gas in the electric heating device 200 is kept at 1 cm to 2 cm radially inward from the heating coil 202 by using a magnetic field, and the heating container 201 is driven to rotate at the same time, so that the sludge and the plasma gas are fully mixed and reacted, and the energy of the plasma is used to break the chemical bonds of the organic compounds in the sludge;

[0042] S5. The sludge mixture treated in step S4 is transported to the sedimentation device 300;

[0043] S6. The sedimentation device 300 provides an anaerobic environment for the sludge mixture and performs sedimentation treatment to promote the sludge mixture to decompose into gas, water and inorganic ash in an anaerobic state.

[0044] Therefore, according to the low-temperature pyrolysis method of municipal sludge provided by the embodiment of the present invention, a magnetic field is used to constrain the plasma gas, so that the plasma gas in the mixing device 100 is maintained at 1 cm to 2 cm away from the inner wall of the mixing container 101, and the plasma gas in the electric heating device 200 is maintained at 1 cm to 2 cm away from the radial inner side of the heating coil 202, so as to prevent the plasma in the plasma gas from being adsorbed by the metal conductor on the inner wall of the container, thereby ensuring that the plasma gas and the sludge can be fully mixed and reacted, so that the energy of the plasma is used to break the chemical bonds of the organic compounds in the sludge, so that the sludge pyrolysis can be carried out in a relatively low temperature environment, thereby reducing energy consumption, reducing the difficulty of temperature control, and extending the service life of the equipment. At the same time, the problem of high-temperature decomposition of various impurities in the sludge to produce dioxins is solved, so as to achieve the purpose of energy saving and environmental protection.

[0045] It should be noted that the heating coil 202 is a high-frequency induction heating coil. The heating coil 202 is located in the mixture of sludge and plasma. The heat source is in full contact with the heating object, and heat loss is small.

[0046] Exemplarily, in step S1, it is required that the sludge cannot fill up the mixing device 100, and the sludge accounts for 70-90% of the volume of the mixing container 101, so as to provide movement space for the sludge and plasma gas to mix. When the mixing container 101 is driven to rotate, the sludge can be driven to roll freely in the mixing container 101 to achieve the stirring effect.

[0047] Exemplarily, in step S2, the specific steps of driving the mixing container 101 to rotate are: first rotating for 15 minutes to 30 minutes, then standing for 10 minutes to 20 minutes, and rotating again for 15 minutes to 30 minutes to fully mix the sludge and the plasma gas.

[0048] Exemplarily, in step S4, the heating coil 202 is heated by a segmented heating method: in the first stage, the temperature of the metal conductor of the wall of the heating container 201 and the sludge mixture is raised to 100°C within 10 minutes; in the second stage, the temperature is kept for 5 to 10 minutes; in the third stage, the temperature of the metal conductor of the wall of the heating container 201 and the sludge mixture is raised to 300°C within 10 minutes; in the fourth stage, the temperature is kept for 5 to 10 minutes; in the fifth stage, the temperature of the metal conductor of the wall of the heating container 201 and the sludge mixture is raised to 450°C within 10 minutes. Thus, the segmented heating method is used for heating so that the plasma and the sludge react fully, and the energy of the plasma is used to break the chemical bonds of the organic compounds in the sludge, and the macromolecular organic matter is converted into small molecular combustible gas and solid residue.

[0049] like Figure 1As shown, based on the above-mentioned municipal sludge low-temperature pyrolysis method, another aspect of the present invention provides a municipal sludge low-temperature pyrolysis system, which includes a mixing device 100, an electric heating device 200 and a precipitation device 300 connected in sequence, the mixing device 100 includes a mixing container 101, a first magnetic strip 102 and a first rotating drive mechanism for driving the mixing container 101 to rotate, the mixing container 101 is provided with a sludge inlet 103 and a plasma inlet 104, the first magnetic strip 102 is provided with a plurality of and is evenly distributed on the outer wall of the mixing container 101 along the circumferential direction of the mixing container 101; the first magnetic strip 102 generates a magnetic field to keep the plasma gas in the mixing container 101 at a distance from the inner wall of the mixing container 101. The electric heating device 200 comprises a heating container 201, a second magnetic strip 203, a heating coil 202 and a second rotating drive mechanism for driving the heating container 201 to rotate, wherein a plurality of the heating coils 202 are uniformly distributed in the heating container 201 along the circumferential direction of the heating container 201 and are located 1cm to 30cm away from the inner wall of the heating container 201; a plurality of the second magnetic strips 203 are uniformly distributed on the outer wall of the heating container 201 along the circumferential direction of the heating container 201; the second magnetic strips 203 generate a magnetic field to compress the plasma gas in the mixing container 101 and keep it at a radial inner side of 1cm to 2cm from the heating coil 202.

[0050] Therefore, according to the municipal sludge low-temperature pyrolysis system provided by the embodiment of the present invention, the magnetic field is used to constrain the plasma gas, so that the plasma gas in the mixing device 100 is maintained at 1 cm to 2 cm away from the inner wall of the mixing container 101, and the plasma gas in the electric heating device 200 is maintained at 1 cm to 2 cm away from the radial inner side of the heating coil 202, so as to prevent the plasma in the plasma gas from being adsorbed by the metal conductor on the inner wall of the container, thereby ensuring that the plasma gas and the sludge can be fully mixed and reacted, so that the energy of the plasma is used to break the chemical bonds of the organic compounds in the sludge, so that the sludge pyrolysis can be carried out in a relatively low temperature environment, thereby reducing energy consumption, reducing the difficulty of temperature control, and extending the service life of the equipment. At the same time, the problem of high-temperature decomposition of various impurities in the sludge to produce dioxins is solved, so as to achieve the purpose of energy saving and environmental protection.

[0051] For example, Figure 1As shown, the sludge outlet of the mixing container 101 is connected to the sludge inlet of the heating container 201 through a first delivery pipeline 400, and the first delivery pipeline 400 is provided with a first delivery pump 401 and a first valve 402; the sludge outlet of the heating container 201 is connected to the sedimentation device 300 through a second delivery pipeline 500, and the second delivery pipeline 500 is provided with a second delivery pump 501 and a second valve 502. The delivery pump provides delivery power for the sludge, and the valve is used to open and close the delivery pipelines between various devices.

[0052] For example, Figure 1 As shown, the main body of the precipitation device 300 is a sealed container, and the precipitation device 300 is provided with a vacuum pump 301 which can discharge the air in the sealed container and form an oxygen-deficient environment.

[0053] For example, Figure 1 and Figure 2 As shown, in order to ensure that the mixing container 101 can rotate stably, the first rotation drive mechanism includes a first motor 105, a first reduction box 106, a first transmission shaft 107, a first driving gear 108 and a first driven gear 109, the power output end of the first motor 105 is connected to the first transmission shaft 107 through the first reduction box 106, the first driving gear 108 is fixedly sleeved on the first transmission shaft 107, the first driven gear 109 is fixed on the outer circumferential wall of the mixing container 101 and is coaxial with the rotation axis of the mixing container 101, and the first driving gear 108 is meshed with the first driven gear 109; the first rotation drive mechanism also includes a plurality of first guide wheel groups 110, among which at least one first guide wheel group 110 is against the bottom of the mixing container 101, at least one first guide wheel group 110 is against the side of the mixing container 101, and at least one first guide wheel group 110 is against the other side of the mixing container 101.

[0054] For example, Figure 1 and Figure 3As shown, in order to ensure that the mixing container 101 can rotate stably, the second rotation drive mechanism includes a second motor 204, a second reduction box 205, a second transmission shaft 206, a second driving gear 207 and a second driven gear 208, the power output end of the second motor 204 is connected to the second transmission shaft 206 through the second reduction box 205, the second driving gear 207 is fixedly sleeved on the second transmission shaft 206, the second driven gear 208 is fixed on the outer circumferential wall of the heating container 201 and is coaxial with the rotation axis of the heating container 201, and the second driving gear 207 is meshed with the second driven gear 208; the second rotation drive mechanism also includes a plurality of second guide wheel groups 209, among which at least one second guide wheel group 209 is against the bottom of the heating container 201, at least one second guide wheel group 209 is against the side of the heating container 201, and at least one second guide wheel group 209 is against the other side of the heating container 201.

[0055] For example, Figure 1 As shown, a stirring rod 111 is provided in the mixing container 101 to achieve a uniform stirring effect for the sludge and the plasma gas.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for low-temperature pyrolysis of municipal sludge, characterized in that: The steps include: S1. Supply sludge into the mixing device; S2. Plasma gas is injected into the mixing device, and the plasma gas in the mixing device is kept at a distance of 1 cm to 2 cm from the inner wall of the mixing container by using a magnetic field, and the mixing container is driven to rotate so that the sludge and the plasma gas are fully mixed; S3. The sludge mixture treated in step S2 is transported to an electric heating device; S4. Turn on the power of the heating coil in the electric heating device, the heating coil is located 1 cm to 30 cm away from the inner wall of the heating container, so that the temperature of the metal conductor of the wall of the heating container and the sludge mixture is controlled not to exceed 500°C, and the plasma gas in the electric heating device is kept at 1 cm to 2 cm radially inward from the heating coil by using a magnetic field, and the heating container is driven to rotate at the same time, so that the sludge and the plasma gas are fully mixed and reacted, and the energy of the plasma is used to break the chemical bonds of the organic compounds in the sludge; S5. The sludge mixture treated in step S4 is transported to a sedimentation device; S6. The sedimentation device provides an anaerobic environment for the sludge mixture and performs sedimentation treatment to promote the decomposition of the sludge mixture into gas, water and inorganic ash in an anaerobic state.

2. The municipal sludge low-temperature pyrolysis method according to claim 1, characterized in that: In the step S1, it is required that the sludge cannot fill up the mixing device, and the volume percentage of the sludge in the mixing container is 70-90%.

3. The municipal sludge low-temperature pyrolysis method according to claim 1, characterized in that: In step S2, the specific steps of driving the mixing container to rotate are: first rotating for 15 minutes to 30 minutes, then standing for 10 minutes to 20 minutes, and rotating again for 15 minutes to 30 minutes.

4. The method for low-temperature pyrolysis of municipal sludge according to claim 1, characterized in that: In step S4, the heating coil is heated in a segmented heating manner: in the first stage, the temperature of the metal conductor of the wall of the heating container and the sludge mixture is raised to 100° C. within 10 minutes; in the second stage, the temperature is kept warm for 5 to 10 minutes; in the third stage, the temperature of the metal conductor of the wall of the heating container and the sludge mixture is raised to 300° C. within 10 minutes; in the fourth stage, the temperature is kept warm for 5 to 10 minutes; The fifth stage raises the temperature of the metal conductor of the heating container wall and the sludge mixture to 450°C within 10 minutes.

5. A municipal sludge low temperature pyrolysis system, characterized in that: The invention comprises a mixing device, an electric heating device and a precipitation device connected in sequence, wherein the mixing device comprises a mixing container, a first magnetic strip and a first rotating driving mechanism for driving the mixing container to rotate, the mixing container is provided with a sludge inlet and a plasma inlet, the first magnetic strip is provided in plurality and is evenly distributed on the outer wall of the mixing container along the circumferential direction of the mixing container; the first magnetic strip generates a magnetic field to keep the plasma gas in the mixing container at a distance of 1 cm to 2 cm from the inner wall of the mixing container; the electric heating device comprises a heating container, a second magnetic strip, a heating coil and a second rotating driving mechanism for driving the heating container to rotate, the heating coil is provided in plurality and is evenly distributed in the heating container along the circumferential direction of the heating container and is located at a distance of 1 cm to 30 cm from the inner wall of the heating container; the second magnetic strip is provided in plurality and is evenly distributed on the outer wall of the heating container along the circumferential direction of the heating container; the second magnetic strip generates a magnetic field to compress the plasma gas in the mixing container and keep it at a distance of 1 cm to 2 cm from the radial inner side of the heating coil.

6. The municipal sludge low-temperature pyrolysis system according to claim 5, characterized in that: The sludge outlet of the mixing container is connected to the sludge inlet of the heating container through a first conveying pipe, and the first conveying pipe is provided with a first conveying pump and a first valve; the sludge outlet of the heating container is connected to the sedimentation device through a second conveying pipe, and the second conveying pipe is provided with a second conveying pump and a second valve.

7. The municipal sludge low-temperature pyrolysis system according to claim 5, characterized in that: The main body of the precipitation device is a sealed container, and the precipitation device is provided with a vacuum pump which can discharge the air in the sealed container and form an oxygen-deficient environment.

8. The municipal sludge low-temperature pyrolysis system according to claim 5, characterized in that: The first rotary drive mechanism comprises a first motor, a first reduction gear, a first transmission shaft, a first driving gear and a first driven gear, wherein a power output end of the first motor is connected to the first transmission shaft through the first reduction gear, the first driving gear is fixedly sleeved on the first transmission shaft, the first driven gear is fixed on the outer circumferential wall of the mixing container and is coaxial with the rotation axis of the mixing container, and the first driving gear is meshed with the first driven gear; The first rotating drive mechanism also includes a plurality of first guide wheel groups, among which at least one first guide wheel group is against the bottom of the mixing container, at least one first guide wheel group is against the side of the mixing container, and at least one first guide wheel group is against the other side of the mixing container.

9. The municipal sludge low-temperature pyrolysis system according to claim 5, characterized in that: The second rotation drive mechanism comprises a second motor, a second reduction gear, a second transmission shaft, a second driving gear and a second driven gear, the power output end of the second motor is connected to the second transmission shaft through the second reduction gear, the second driving gear is fixedly sleeved on the second transmission shaft, the second driven gear is fixed on the outer circumferential wall of the heating container and is coaxial with the rotation axis of the heating container, and the second driving gear is meshed with the second driven gear; The second rotating drive mechanism also includes multiple second guide wheel groups, among which at least one second guide wheel group is against the bottom of the heating container, at least one second guide wheel group is against the side of the heating container, and at least one second guide wheel group is against the other side of the heating container.

10. The municipal sludge low-temperature pyrolysis system according to claim 5, characterized in that: A stirring rod is arranged in the mixing container.

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