A pyrolysis device and pyrolysis method with nitrogen protection and controllable pyrolysis time of feed

Abstract

The present invention relates to the technical field of solid waste treatment, and discloses a pyrolysis device and a pyrolysis method with controllable pyrolysis time of nitrogen-protected feed. The feed assembly of the present invention comprises a hopper and a nitrogen-protected chamber located below the hopper. The inner cavity wall of the shell of the nitrogen-protected chamber is in an hourglass shape with large ends and a small middle, and is connected to the hopper. The filter is arranged in the upper section of the shell and is connected to the exhaust pipe. The gas distributor is arranged in the material layer in the shell and is connected to the nitrogen tank. The shell is connected to the pyrolysis reactor; the pyrolysis reactor comprises an internally hollow casing, a variable pitch shaftless spiral horizontally arranged in the casing, and a heating device arranged on the casing; the variable pitch shaftless spiral is arranged horizontally, and the driving end is arranged near the feeding port of the casing, and is fixedly connected to the motor driving shaft outside the casing, and the pitch or pitch ladder of the variable pitch shaftless spiral gradually decreases from the driving end to the free end. The feed of the present invention is safe, and the residence time of solid materials at different positions in the reactor is controllable.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste treatment, and in particular to a pyrolysis device and a pyrolysis method with controllable pyrolysis time of feed protected by nitrogen. Background Art

[0002] The medical, chemical, metallurgical, and papermaking industries generate a large amount of organic solid waste with low biodegradability, high toxicity, and complex composition during production. Meanwhile, large cities also generate a large amount of municipal sludge, plastic waste, etc. The traditional method of treating organic solid waste is to incinerate or melt it in an oxidizing atmosphere, but this also brings about the problem of re-synthesis of dioxins in the flue gas.

[0003] European and American countries began to conduct research and demonstration applications of pyrolysis technology in the 1990s, and my country followed suit. The difference between pyrolysis and incineration is that the anoxic treatment can effectively inhibit the synthesis of dioxin pollutants and stabilize heavy metals (Cu, Pb and Zn) in the solid phase products.

[0004] Most of the existing pyrolysis furnaces in my country still use intermittent processing. Intermittent feeding mainly means that after a furnace is fed, it is sealed for pyrolysis, discharged, and the above steps are repeated. Intermittent pyrolysis furnaces have low efficiency, low degree of automation, and high safety risks.

[0005] The domestic pyrolysis equipment that adopts continuous feeding and discharging can only isolate most of the air from entering, and it is difficult to achieve complete oxygen elimination. The main reason is that due to the different properties of solid materials, it is easy to cause blockage and sticking problems, resulting in unstable operation of the conveying equipment. In addition, the continuous feeding method is difficult to completely remove the oxygen entrained in the material. There are also certain safety hazards when oxygen enters the pyrolysis furnace. When the oxygen entering the pyrolysis furnace reaches a certain concentration, there will be a safety risk of combustion and explosion.

[0006] In order to remove oxygen entrained in the material, some existing pyrolysis equipment adopts spiral feeding and / or vacuum methods, which can discharge most of the oxygen in the material, but it cannot be completely isolated. The oxygen content in the pyrolysis furnace cannot be known in time, which poses certain safety hazards and is prone to problems such as material sticking, sticking, and clogging. Summary of the invention

[0007] The invention provides a pyrolysis device with nitrogen protection and controllable pyrolysis time for feed, which has safe feed and controllable residence time of solid materials at different positions in a reactor.

[0008] The technical problem to be solved is that the existing pyrolysis equipment cannot completely solve the problem of oxygen entrained in the material, and lacks a supporting monitoring and processing system, which poses certain safety hazards.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] The invention discloses a pyrolysis device with controllable pyrolysis time of nitrogen-protected feed, comprising a feed assembly, a pyrolysis reactor and a control system, wherein the feed assembly comprises a hopper and a nitrogen protection chamber located below the hopper, the nitrogen protection chamber comprises a shell, a gas distributor and a filter located inside the shell, and a nitrogen tank located outside the shell; the inner cavity wall of the shell is in an hourglass shape with large ends and a small middle, a feed inlet at the top is connected to a discharge outlet at the lower end of the hopper, the filter is arranged at an upper section of the shell, an air outlet is communicated with an exhaust pipe, an exhaust outlet of the exhaust pipe extends to the outside of the shell, and the gas distributor is arranged at a lower section of the shell. The gas distributor is arranged in the material layer in the shell, the air inlet of the gas distributor is connected to the nitrogen tank through a nitrogen pipe, and the bottom outlet of the shell is connected to the feed inlet of the pyrolysis reactor; the pyrolysis reactor includes an internally hollow shell, a variable pitch shaftless spiral body horizontally arranged in the shell, and a heating device arranged on the shell; the variable pitch shaftless spiral body is horizontally arranged, the driving end is arranged near the feed inlet of the shell, and is fixedly connected to the motor driving shaft outside the shell, and the pitch or pitch ladder of the variable pitch shaftless spiral body gradually decreases from the driving end to the free end.

[0011] The present invention discloses a pyrolysis device with nitrogen protection and controllable pyrolysis time for feeding. Furthermore, the hopper is a hopper-shaped structure with a larger upper portion and a smaller lower portion, and a rotating scraper is arranged in the hopper near a lower discharge port.

[0012] The present invention provides a pyrolysis device with controllable pyrolysis time for nitrogen-protected feed. Furthermore, a material guide plate is arranged just below the feed port at the top of the nitrogen-protected bin. The material guide plate is arranged to be inclined downward, and the top edge is fixedly connected to the inner wall of the shell.

[0013] The present invention provides a pyrolysis device with controllable pyrolysis time of nitrogen-protected feed. Furthermore, the hopper is connected to the nitrogen protection bin via a first air lock valve, and the bottom outlet of the nitrogen protection bin is connected to the feed inlet of the pyrolysis reactor via a second air lock valve.

[0014] The present invention provides a pyrolysis device with controllable pyrolysis time of nitrogen-protected feed. Further, a pressure control valve is arranged on the exhaust pipe, and a signal input end of the pressure control valve is electrically connected to a signal output end of a controller.

[0015] The present invention provides a pyrolysis device with controllable pyrolysis time of nitrogen-protected feed. Further, a pressure reducing valve is arranged on the nitrogen pipe, and a signal input end of the pressure reducing valve is electrically connected to a signal output end of a control system.

[0016] The present invention discloses a pyrolysis device with controllable pyrolysis time of nitrogen-protected feed. Furthermore, an oxygen online detector is arranged in the nitrogen protection chamber, and a signal output end of the oxygen online detector is electrically connected to a signal input end of a control system.

[0017] The present invention provides a pyrolysis device with controllable pyrolysis time for nitrogen-protected feed. Furthermore, the pitch of the variable-pitch shaftless screw decreases at equal distances from the driving end to the free end, and the minimum pitch is 95% to 30% of the maximum pitch.

[0018] The present invention provides a pyrolysis device with controllable pyrolysis time of nitrogen-protected feed. Furthermore, the pitch steps of the variable-pitch shaftless spiral are divided into 5-8 levels, the pitch decreases at equal distances from the driving end to the free end, and the minimum pitch is 95%-30% of the maximum pitch.

[0019] The present invention provides a pyrolysis method for a pyrolysis device with nitrogen protection and controllable pyrolysis time of feed, characterized in that it comprises the following steps:

[0020] Step 1: Solid materials enter the nitrogen protection chamber through the hopper;

[0021] Step 2: The solid material falls evenly to cover the gas distributor, and the high-pressure nitrogen is evenly introduced into the solid material through the gas distributor, displacing the air entrained in the material, leading it to the upper cavity of the shell, and then discharged from the shell after filtering;

[0022] Step 3: The material protected by nitrogen enters the pyrolysis reactor and is transported by a variable pitch shaftless screw, and undergoes pyrolysis reaction during the transport process;

[0023] Step 4: The pyrolysis-completed material and the pyrolysis gas generated during the pyrolysis process are discharged separately, and the pyrolysis is completed.

[0024] Compared with the prior art, the pyrolysis device of the present invention with nitrogen protection and controllable pyrolysis time of feed has the following beneficial effects:

[0025] The present invention adopts a nitrogen protection feeding mode, sets up an independent nitrogen protection chamber, uses nitrogen to fully replace the oxygen in the material, monitors the oxygen content in the nitrogen protection chamber in real time, and adjusts and controls it to ensure the adequacy of the replacement. The anaerobic effect is good, and the safety hazards caused by excessive oxygen content can be effectively avoided.

[0026] The present invention adopts a variable pitch shaftless screw conveyor, which is first wide and then narrow. According to the change in the volume of different solid materials after pyrolysis, by selecting and controlling the degree of change in the pitch, the residence time of the solid materials at different positions along the axial direction of the pyrolysis reactor can be clearly controlled, so that the solid materials can be fully pyrolyzed while preventing local temperature from rising too fast and coking. The device is suitable for the pyrolysis of different types of solid materials, has a wide range of applications, and is highly practical.

[0027] The following is a further description of a pyrolysis device with controllable pyrolysis time of feed under nitrogen protection according to the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a schematic structural diagram of a pyrolysis device with nitrogen protection and controllable pyrolysis time for feed.

[0029] Reference numerals:

[0030] 1-hopper; 21-shell; 22-gas distributor; 23-filter; 24-exhaust pipe; 25-pressure control valve; 31-first air lock valve; 32-second air lock valve; 4-nitrogen tank; 41-nitrogen pipe; 42-pressure reducing valve; 5-casing; 51-feeding port; 52-discharging port; 53-pyrolysis gas outlet; 6-variable pitch shaftless screw; 61-motor; 7-heating device; 8-rotating scraper; 9-guide plate. DETAILED DESCRIPTION

[0031] like Figure 1 As shown, a pyrolysis device with controllable pyrolysis time of nitrogen-protected feedstock includes a feed assembly, a pyrolysis reactor and a control system. The solid material discharge port of the feed assembly is connected to the feed port 51 of the pyrolysis reactor.

[0032] The feeding assembly includes a hopper 1 at the top and a nitrogen protection chamber located below the hopper 1. The hopper 1 is a bucket-shaped structure with a larger top and a smaller bottom. A rotating scraper 8 is provided near the lower discharge port in the hopper 1 to prevent sticky materials and fine powder materials from sticking to the hopper 1. The discharge port at the lower end of the hopper 1 is connected to the top feed port of the nitrogen protection chamber through a first air lock valve 31.

[0033] The nitrogen protection bin includes a shell 21, a gas distributor 22 and a filter 23 located in the shell 21, and a nitrogen tank 4 located outside the shell 21; the inner cavity wall of the shell 21 is in the shape of an hourglass with large ends and a small middle, and the top feed port is connected to the first air lock valve 31 to prevent a large amount of air in the hopper 1 from entering the nitrogen protection bin. A guide plate 9 is arranged directly below the top feed port. The guide plate 9 is tilted downward, and the top edge is fixedly connected to the inner wall of the shell 21. The angle between the guide plate 9 and the horizontal plane is not greater than 50°, which can effectively slow down the falling speed of the material, avoid the material from falling in one place, and facilitate the material to be evenly and loosely dispersed in the gas distributor 22 below. The filter 23 is arranged in the upper section of the shell 21 and is located on the back side of the guide plate 9. The filter 23 can specifically be a cyclone filter. The air outlet of the filter 23 is connected to the exhaust pipe 24. The exhaust port of the exhaust pipe 24 extends to the outside of the shell 21 and is connected to the atmosphere or other exhaust gas purification devices. A pressure control valve 25 is arranged on the exhaust pipe 24, and the signal input end of the pressure control valve 25 is electrically connected to the signal output end of the controller. The gas distributor 22 is arranged in the material layer in the shell 21, and the arrangement height is generally not more than 2 / 3 of the height of the shell 21. The air inlet of the gas distributor 22 is connected to the nitrogen tank 4 through the nitrogen pipe 41. The nitrogen pipe 41 is provided with a pressure reducing valve 42 to control the pressure of the nitrogen entering the gas distributor 22. The signal input end of the pressure reducing valve 42 is electrically connected to the signal output end of the control system. The gas distributor 22 uniformly introduces nitrogen into the material layer, replaces the air entrained in the material, and guides it to the upper space of the shell 21. After being filtered by the filter 23, it is discharged from the shell 21. The pressure in the nitrogen protection chamber is controlled by the pressure control valve 25 to be controlled below 1000Pa. When the pressure in the nitrogen protection chamber is higher than the set value, the pressure control valve 25 is opened to discharge the gas in the chamber. When the pressure in the nitrogen protection chamber is lower than the set value, the pressure control valve 25 is closed. The bottom outlet of the nitrogen protection chamber is connected to the feed port 51 of the pyrolysis reactor through the second air lock valve 32.

[0034] An oxygen online detector is provided in the nitrogen protection chamber. The signal output terminal of the oxygen online detector is electrically connected to the signal input terminal of the control system. The oxygen online detector transmits the signal monitored in the nitrogen protection chamber to the control system. When the monitored oxygen concentration signal exceeds the set value, the control system controls to increase the opening of the pressure control valve 25, increases the exhaust speed, and at the same time controls to increase the opening of the pressure reducing valve 42, increases the input amount of nitrogen, and increases the dilution and carry-out amount of oxygen.

[0035] The pyrolysis reactor is a horizontal spiral pyrolysis reactor, including a casing 5 with a hollow interior, a variable pitch shaftless spiral 6 horizontally arranged in the casing 5, and a heating device 7 arranged on the casing 5; a feed port 51 is provided at the top of one side of the casing 5, a discharge port 52 is provided at the bottom of the horizontally opposite side, a pyrolysis gas outlet 53 is provided at the top of the casing 5, close to the discharge port 52, and the feed port 51 of the casing 5 is connected to the second air lock valve 32; the variable pitch shaftless spiral 6 is horizontally arranged, and the driving end is arranged close to the feed port 51 of the casing 5, and is fixedly connected to the driving shaft of the motor 61 outside the casing 5, and is driven by the motor 61 to rotate around the horizontal axis direction, and the variable pitch The free end of the shaftless screw 6 is arranged near the discharge port 52 of the casing 5; the pitch of the variable-pitch shaftless screw 6 gradually decreases from the driving end to the free end, preferably, the pitch decreases at equal intervals, and the minimum pitch is 95%~30% of the maximum pitch; or the pitch steps of the variable-pitch shaftless screw 6 gradually decrease from the driving end to the free end, preferably, can be divided into 5-8 levels, the pitch decreases at equal intervals, and the minimum pitch is 95%~30% of the maximum pitch; the heating device 7 is arranged to cover the surface of the casing 5, and can be arranged on the inner wall of the casing 5, or on the outer wall of the casing 5, with the heating effect and heating requirements as the standard, without limiting the specific implementation technical means.

[0036] The shaftless screw can effectively prevent sticky materials from sticking and avoid clogging in the pyrolysis reactor; the variable pitch can well control the residence time of solid materials at different positions along the axial direction of the pyrolysis reactor, so that the solid materials can be fully pyrolyzed while preventing local temperature from rising too quickly and causing coking.

[0037] More specifically, in this embodiment, the pitch steps of the variable pitch shaftless screw 6 gradually decrease from the driving end to the free end, and can be specifically divided into two levels, with a wider pitch of 30 cm at the driving end and a narrower pitch of 10 cm at the free end.

[0038] The device is used to pyrolyze Fischer-Tropsch synthesis slag wax. The oxygen content in the reactor is 20ppm, which is in a very safe oxygen concentration range. The pyrolysis residue of the slag wax is less than 0.1%, and there is no coking or blockage in the reactor.

[0039] The present invention provides a pyrolysis method of a pyrolysis device with nitrogen protection and controllable pyrolysis time of feed, which specifically comprises the following steps:

[0040] Step 1: Solid materials enter the hopper 1 and enter the nitrogen protection chamber under the stirring of the rotating scraper 8. The rotating scraper 8 can effectively prevent sticky materials and fine powder materials from sticking to the hopper 1;

[0041] Step 2: The solid material is dispersed by the guide plate 9 and falls evenly to cover the gas distributor 22. The high-pressure nitrogen is evenly introduced into the solid material through the gas distributor 22, displacing the air entrained in the material and leading it to the upper cavity of the shell 21. It is filtered by the filter 23 and then discharged from the shell 21.

[0042] The pressure in the nitrogen protection chamber is controlled to be below 1000Pa by the pressure control valve 25. When the pressure in the nitrogen protection chamber is higher than the set value, the pressure control valve 25 opens to discharge the gas in the chamber. When the pressure in the nitrogen protection chamber is lower than the set value, the pressure control valve 25 closes. This gas replacement process can replace the air in most of the solid materials and discharge them out of the nitrogen protection chamber. The residual gas between the material particles is high-purity nitrogen, which will not have any effect on pyrolysis. At the same time, there is no safety hazard caused by the residual nitrogen.

[0043] Step 3: The material protected by nitrogen enters the pyrolysis reactor, is transported by the wide spiral and the narrow spiral in sequence, and undergoes pyrolysis reaction during the transport process;

[0044] A wider pitch is set in the front section of transportation after the material enters. The wide pitch is set in the front section mainly to solve the congestion of just feeding and ensure smooth feeding. The wider pitch can ensure the looseness of the material and facilitate the full pyrolysis reaction. At the same time, because it is a shaftless screw, the viscous material will not cause blockage or jamming during the transportation process. The narrow pitch is set in the rear section to compact the solid material and squeeze out the gas entrained in the solid material during the feeding process to achieve the purpose of anaerobic treatment.

[0045] Step 4: The material after pyrolysis is discharged from the discharge port 52 on the narrow pitch side, and the pyrolysis gas generated during the pyrolysis process is discharged from the pyrolysis gas outlet 53, completing the entire pyrolysis process; during the entire pyrolysis process, the oxygen online detector monitors the oxygen concentration in the pyrolysis reactor in real time. When the concentration exceeds the warning value, when the set oxygen concentration is higher than the set value, the opening of the pressure control valve 25 and the pressure reducing valve 42 increases, increasing the replacement of nitrogen and oxygen.

[0046] The embodiments described above are merely descriptions of preferred implementation modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A pyrolysis device with nitrogen protection and controllable pyrolysis time of feed, characterized in that: The invention comprises a feed assembly, a pyrolysis reactor and a control system. The feed assembly comprises a hopper (1) and a nitrogen protection chamber located below the hopper (1). The nitrogen protection chamber comprises a shell (21), a gas distributor (22) and a filter (23) located inside the shell (21), and a nitrogen tank (4) located outside the shell (21). A guide plate (9) is arranged directly below a feed opening at the top of the nitrogen protection chamber. The guide plate (9) is arranged to be tilted downward, and a top edge is fixedly connected to an inner wall of the shell (21). The inner cavity wall of the shell (21) is in an hourglass shape with large ends and a small middle. The top feed opening is connected to a discharge opening at the lower end of the hopper (1). The filter (23) is arranged at the upper section of the shell (21). The gas outlet is communicated with an exhaust pipe (24). The exhaust opening of the exhaust pipe (24) extends to the outside of the shell (21). The gas distributor (22) is arranged at the shell ( 21), the gas inlet of the gas distributor (22) is connected to the nitrogen tank (4) through the nitrogen pipe (41), and the bottom outlet of the shell (21) is connected to the feed port (51) of the pyrolysis reactor; the pyrolysis reactor comprises an internally hollow casing (5), a variable pitch shaftless screw (6) horizontally arranged in the casing (5), and a heating device (7) arranged on the casing (5); the variable pitch shaftless screw (6) is horizontally arranged, the driving end is arranged near the side of the feed port (51) of the casing (5), and is fixedly connected to the driving shaft of the motor (61) outside the casing (5), the pitch or pitch ladder of the variable pitch shaftless screw (6) gradually decreases from the driving end to the free end, the pitch of the variable pitch shaftless screw (6) decreases at equal distances from the driving end to the free end, and the minimum pitch is 95% to 30% of the maximum pitch.

2. A pyrolysis device with controllable pyrolysis time of feed protected by nitrogen according to claim 1, characterized in that: The hopper (1) is a bucket-shaped structure that is larger at the top and smaller at the bottom. A rotating scraper (8) is provided in the hopper (1) near the lower discharge port.

3. A pyrolysis device with controllable pyrolysis time of feed protected by nitrogen according to claim 1, characterized in that: The hopper (1) is connected to the nitrogen protection chamber via a first air lock valve (31), and the bottom outlet of the nitrogen protection chamber is connected to the feed port (51) of the pyrolysis reactor via a second air lock valve (32).

4. The pyrolysis device with controllable pyrolysis time of feed material protected by nitrogen according to claim 1, characterized in that: The exhaust pipe (24) is provided with a pressure control valve (25), and a signal input end of the pressure control valve (25) is electrically connected to a signal output end of the controller.

5. The pyrolysis device with controllable pyrolysis time of feed protected by nitrogen according to claim 1, characterized in that: The nitrogen pipe (41) is provided with a pressure reducing valve (42), and a signal input end of the pressure reducing valve (42) is electrically connected to a signal output end of the control system.

6. The pyrolysis device with controllable pyrolysis time of feed material protected by nitrogen according to claim 1, characterized in that: An oxygen online detector is arranged in the nitrogen protection chamber, and a signal output end of the oxygen online detector is electrically connected to a signal input end of the control system.

7. The pyrolysis device with controllable pyrolysis time of feed material protected by nitrogen according to claim 1, characterized in that: The pitch of the variable pitch shaftless screw (6) is divided into 5-8 levels, the pitch decreases at equal distances from the driving end to the free end, and the minimum pitch is 95%-30% of the maximum pitch.

8. A pyrolysis method for a pyrolysis device with nitrogen protection and controllable pyrolysis time of feed according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: solid materials enter the nitrogen protection chamber through the hopper (1); Step 2: The solid material falls evenly to cover the gas distributor (22), and the high-pressure nitrogen is evenly introduced into the solid material through the gas distributor (22), displacing the air entrained in the material and leading it into the upper cavity of the shell (21), and then discharged from the shell (21) after being filtered; Step 3: The material protected by nitrogen enters the pyrolysis reactor and is transported by a variable pitch shaftless screw, and undergoes pyrolysis reaction during the transport process; Step 4: The pyrolysis-completed material and the pyrolysis gas generated during the pyrolysis process are discharged separately, and the pyrolysis is completed.

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