Sludge treatment energy recycling device based on crystallization decomposition

Abstract

The present application relates to sludge treatment technical field, disclose a kind of sludge treatment energy cycle device based on crystallization decomposition, the device includes hydrate synthesis tower, hydrate decomposition tower, pressure self-balancing column lock, gas circulation compressor and sludge precooling plate heat exchanger.Wall surface cleaning drive component is equipped in hydrate synthesis tower vertical spiral heat exchange tube bundle and, pressure self-balancing column lock includes feed standpipe, discharge standpipe and U-shaped communication section, wall surface cleaning drive component includes vertical spindle, magnetic coupling driver, horizontal spoke and flexible spiral blade, and flexible spiral blade is continuously cleaned with vertical spindle rotation to heat exchange tube bundle outer wall surface.Pressure self-balancing column lock utilizes sludge column static pressure head to balance the pressure difference of two towers, realize the continuous transport of sludge.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge treatment, and more specifically, it relates to an energy circulation device for sludge treatment based on crystallization and decomposition. Background Art

[0002] Sludge produced during the sewage treatment process in sewage plants is sediments converted from pollutants and microbial residues converted from pollutants in the biological sewage treatment process. High moisture content is the main factor restricting the efficiency of sludge treatment. Dewatering can achieve sludge volume reduction, reduced fluidity and increased incineration calorific value, which is a common key technical link in sludge treatment and disposal. In the prior art, the hydrate method is used to dewater sludge. The sludge is brought into contact with a medium in a vertical high-pressure synthesis tower to form hydrate, and the hydrate-containing sludge is discharged to a normal-pressure decomposition tower to release low-temperature gas. The low-temperature gas is returned to the synthesis tower after heat exchange and compression to form a closed-loop cascaded cold energy cycle.

[0003] The above process has two interrelated technical problems. First, high-viscosity humus colloid precipitates on the cold wall surface of the heat exchange tube bundle and adheres to form a mucosal layer, and the initially crystallized hydrate crystal grains simultaneously attach to the cold wall surface, resulting in increased heat transfer thermal resistance and blockage of the flow passages between the tube bundles, so that the cold energy cannot be effectively transferred, leading to insufficient hydrate generation. Second, the sludge also contains inorganic sand with high adhesiveness. When the sand-containing sludge is discharged from the high-pressure tower to the normal-pressure tower through a rotary valve or gate valve, the hard sand grains cause abrasive wear on the valve body sealing surface, and the sealing failure leads to high-pressure channeling leakage, which increases the pressure on the suction side of the gas circulation compressor and destabilizes the closed-loop cold energy cycle. Failure of any link will make the entire cascaded cold energy recovery system unable to operate stably. Summary of the Invention

[0004] The present invention provides an energy circulation device for sludge treatment based on crystallization and decomposition, which solves the technical problems in the related art that the precipitation and adhesion of high-viscosity humus colloid on the cold wall surface of the heat exchange tube bundle leads to heat transfer efficiency attenuation, and the abrasive wear of sand-containing sludge on the valve body sealing surface leads to sealing failure.

[0005] This invention discloses a sludge treatment energy recycling device, comprising a vertically pressurized synthesis tower tank, vertically spiral heat exchange tube bundles evenly distributed circumferentially inside the synthesis tower tank, a wall cleaning drive assembly, a pressure self-balancing material column lock, a decomposition tower body, and a gas circulation system. The vertically spiral heat exchange tube bundles are evenly distributed circumferentially inside the synthesis tower tank, with the top and bottom ends of each tube bundle converging into upper and lower annular manifolds, respectively. The wall cleaning drive assembly includes a vertical main shaft, a magnetically coupled actuator, horizontal spokes, and a flexible spiral scraper. The vertical main shaft is arranged along the central axis of the synthesis tower tank, the horizontal spokes are fixed to the vertical main shaft and extend radially, and the flexible spiral scraper is fixed to the outer end of the horizontal spokes and contacts the outer wall of the vertically spiral heat exchange tube bundle. The pressure self-balancing material column lock includes a feed riser, a discharge riser, and a U-shaped connecting section. The feed riser extends downward from the bottom of the synthesis tower tank, and the discharge riser extends upward to the decomposition tower body. The U-shaped connecting section connects the bottom ends of the two risers. The static pressure head of the sludge material column in the feed riser balances the pressure difference between the two towers.

[0006] Furthermore, the magnetically coupled actuator includes an outer magnetic rotor, a magnetically coupled isolation sleeve, and an inner magnetic rotor. The magnetically coupled isolation sleeve is fixed to the top of the synthesis tower tank and forms a pressure boundary wall. The inner magnetic rotor is located inside the magnetically coupled isolation sleeve and is connected to the top of the vertical main shaft via a spline. The outer magnetic rotor is located outside the magnetically coupled isolation sleeve and surrounds its outer wall. The vertical main shaft is radially and axially supported by a main shaft bearing fixed to the inner wall of the synthesis tower tank.

[0007] Furthermore, a tower top flange support is fixedly installed on the outer side of the top flange face of the synthesis tower tank, and the geared motor is fixed to the tower top flange support. The output shaft of the geared motor points vertically downward into the tank and is fixedly connected to the external magnetic rotor.

[0008] Furthermore, the flexible spiral scraper is a polytetrafluoroethylene strip with an arc-shaped cross-section to conform to the cylindrical outer wall of the vertical spiral heat exchanger tube bundle. The strip is arranged in a spiral winding pattern along the axial direction of the vertical spiral heat exchanger tube bundle. One long side of the strip is fixed to the outer end of the horizontal spoke, and the arc surface of the other long side forms a sliding friction pair with the outer wall of the vertical spiral heat exchanger tube bundle.

[0009] Furthermore, a compression spring arranged radially is provided between the outer end of the horizontal spoke and the flexible spiral scraper. One end of the compression spring is fixed to the inner wall of the sleeve at the outer end of the horizontal spoke, and the other end abuts against the fixing seat of the flexible spiral scraper. The compression spring provides pre-tightening pressure radially to make the flexible spiral scraper fit against the outer wall surface of the vertical spiral heat exchange tube bundle.

[0010] Furthermore, the top ends of each vertical spiral heat exchanger tube bundle converge into the upper annular manifold, and the bottom ends of each vertical spiral heat exchanger tube bundle converge into the lower annular manifold. The upper and lower annular manifolds are fixed to the upper and lower parts of the inner cavity of the synthesis tower tank, respectively, and surround the central axis of the synthesis tower tank. The upper annular manifold is used to introduce the refrigerant, and the lower annular manifold is used for refrigerant reflux. A CO2 inlet main is fixed at the top of the synthesis tower tank, a sludge inlet is opened on the middle side wall of the synthesis tower tank, and a conical hopper for collecting hydrate-containing sludge is fixed at the bottom of the synthesis tower tank. The outlet of the conical hopper is connected to the top of the feed riser.

[0011] Furthermore, the pressure self-balancing material column lock also includes a gate assembly and an external support for the material column lock. The external support provides structural support around the outside of the feed riser, discharge riser, and U-shaped connecting section. The gate assembly includes an upper gate at the feed end, an upper gate at the discharge end, and two lower gates. The upper gate at the feed end is located at the top of the feed riser and is embedded in the guide groove of the gate seat hole in the pipe wall, moving linearly in the horizontal direction. The upper gate at the discharge end is located at the top of the discharge riser and has the same structure as the upper gate at the feed end. The two lower gates are located in the guide grooves of the gate seat holes on both sides of the U-shaped connecting section. Under normal operating conditions, all gates are in the fully open position.

[0012] Furthermore, the cylinder body of the upper gate cylinder at the feeding end is fixed to the outer side of the top of the feeding riser of the external support of the material column lock, and the piston rod of the upper gate cylinder at the feeding end is connected to the upper gate at the feeding end. The cylinder body of the upper gate cylinder at the discharging end is fixed to the outer side of the top of the discharging riser of the external support of the material column lock, and the piston rod of the upper gate cylinder at the discharging end is connected to the upper gate at the discharging end. The cylinder bodies of the two lower gate cylinders are respectively fixed to the outer sides of the U-shaped connecting section of the external support of the material column lock, and the piston rod of each lower gate cylinder is connected to the corresponding lower gate.

[0013] Furthermore, a stepped material distribution plate is fixed to the inner wall of the decomposition tower, with each step arranged in a staggered manner along the height direction. A conical discharge port is fixed to the bottom of the decomposition tower, with the conical surface contracting downwards to collect the dewatered sludge. A top vent pipe is fixed to the top of the decomposition tower.

[0014] Furthermore, it also includes a precooling plate heat exchanger, a gas recirculation compressor, a condenser, and a dryer. The top outlet pipe of the tower is connected to the hot-side inlet of the precooling plate heat exchanger, and the hot-side outlet of the precooling plate heat exchanger is connected to the suction inlet of the gas recirculation compressor. The exhaust port of the gas recirculation compressor is connected to the CO2 main inlet pipe of the synthesis tower tank via the condenser and the dryer, forming a closed-loop CO2 gas circulation circuit. The cold-side inlet of the precooling plate heat exchanger is connected to the sludge feed pipeline, and the cold-side outlet of the precooling plate heat exchanger is connected to the sludge feed inlet of the synthesis tower tank.

[0015] This invention solves the technical problems of increased heat exchange resistance and insufficient hydrate formation caused by the adhesion of high-viscosity humic colloids and initial hydrate crystals to the cold wall surface, which are driven by a wall cleaning drive component to continuously clean the outer wall surface of the vertical spiral heat exchange tube bundle. This achieves the technical effect that the heat transfer coefficient of the heat exchange tube bundle does not decrease with operating time and that cold energy can be continuously transferred to the sludge free water. Furthermore, this invention uses a pressure self-balancing material column lock to balance the pressure difference between the two towers by utilizing the static pressure head generated by the weight of the sludge column in the feed riser. This solves the technical problem of abrasive wear and seal failure caused by hard sand particles on the sealing surface when sand-containing sludge is discharged through the valve, leading to circulation instability. This achieves the technical effect that sand particles do not contact the gate sealing surface and the sealing performance does not degrade due to long-term passage of sand-containing materials. The combined effect of these two methods solves the technical problem that the overall closed-loop cascade cold energy recovery cycle cannot operate steadily under high-viscosity sand-containing conditions, achieving the technical effect that the overall circulation system can operate steadily for a long time. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the energy recycling device for sludge treatment based on crystallization decomposition of the present invention. Figure 2 This is a front view of the sludge treatment energy recycling device based on crystallization decomposition according to the present invention; Figure 3 This is a longitudinal sectional view of the hydrate synthesis tower of the present invention; Figure 4 This is a cross-sectional view of the hydrate synthesis tower of the present invention; Figure 5 This is a longitudinal sectional view of the pressure self-balancing material column lock and hydrate decomposition tower of the present invention. Figure 6 This is a schematic diagram of the flexible spiral scraper, elastic connector, and horizontal spokes of the present invention.

[0017] In the diagram: 1. Synthesis tower tank; 2. Spiral heat exchanger tube bundle; 3. Upper annular manifold; 4. Lower annular manifold; 5. CO2 inlet main pipe; 6. Sludge inlet; 7. Conical hopper; 8. Tower top flange support; 9. Gear motor; 10. External magnetic rotor; 11. Magnetic coupling isolation sleeve; 12. Internal magnetic rotor; 13. Vertical main shaft; 14. Horizontal spokes; 15. Flexible spiral scraper; 16. Compression spring; 17. Material column lock external support; 18. Feed riser; 19. Discharge riser; 20. U-shaped connecting section; 21. Upper gate at the feed end; 22. Upper gate cylinder at the feed end; 23. Upper gate at the discharge end; 24. Upper gate cylinder at the discharge end; 25. Lower gate; 26. Lower gate cylinder; 27. Decomposition tower body; 28. Stepped distribution plate; 29. ​​Conical discharge port; 30. Top gas outlet pipe; 31. Precooling plate heat exchanger; 32. Gas recirculation compressor; 33. Condenser; 34. Dryer; 35. Main shaft bearing. Detailed Description

[0018] Sludge refers to the sediment converted from pollutants and microbial residues transformed from pollutants in the sewage treatment process; high moisture content is the main factor restricting the sludge treatment efficiency, and dewatering can realize sludge volume reduction, fluidity reduction and incineration calorific value improvement, which is a common key technical link in sludge treatment and disposal. However, sludge is a highly mixed organic-inorganic colloidal floc structure with strong water holding capacity and extremely poor solid-liquid separation performance, making dewatering treatment difficult. When the hydrate method is used for dewatering such sludge, the sludge contacts with the reactant in a vertical high-pressure synthesis tower to form hydrate, and the hydrate-containing sludge is discharged to an atmospheric pressure decomposition tower to release low-temperature gas, which is returned to the synthesis tower after heat exchange and compression to form a closed-loop cascade cold energy cycle. This process has two interrelated technical problems: first, the high-viscosity humus colloid rapidly precipitates and adheres to the cold wall surface of the heat exchange tube bundle to form a mucous membrane layer, and the initially crystallized hydrate crystal grains simultaneously attach to the cold wall surface, resulting in a sharp increase in heat transfer resistance and blockage of the flow channels between the tube bundles, so that the cold energy cannot be effectively transferred, leading to the attenuation of crystallization rate and insufficient hydrate generation; second, when the sand-containing sludge is discharged from the high-pressure tower to the atmospheric pressure tower through a rotary valve or gate valve, the hard sand particles cause severe abrasive wear on the sealing surface of the valve body, and the sealing failure leads to high-pressure leakage, which increases the pressure on the suction side of the compressor and destabilizes the closed-loop cold energy cycle. Wall contamination leads to insufficient hydrate generation and thus insufficient cold release in the decomposition tower, and sealing failure leads to the disappearance of the pressure difference between the two towers and thus cycle interruption. Failure of any link will prevent the entire cascade cold energy recovery system from operating stably.

[0019] This embodiment provides a sludge treatment energy cycle device based on crystallization and decomposition, comprising: as Figure 1 shown, the device includes a hydrate synthesis tower, a hydrate decomposition tower, a pressure self-balancing material column lock connecting the two towers, a gas circulation compressor 32 and a sludge pre-cooling plate heat exchanger 31.

[0020] The hydrate synthesis tower is a synthesis tower tank 1, and its pressure-bearing cavity provides a high-pressure closed reaction space. As Figure 4 shown, six rows of vertical spiral heat exchange tube bundles 2 are evenly distributed along the circumferential direction in the synthesis tower tank 1, the axis of each tube bundle is arranged in the vertical direction, and is located in the annular area between the central axis of the synthesis tower tank 1 and the tank wall. The top ends of the tube bundles are merged into the upper annular header 3, and the bottom ends of the tube bundles are merged into the lower annular header 4. The upper annular header 3 and the lower annular header 4 are respectively fixed at the upper part and the lower part of the inner cavity of the tank 1 and surround the central axis of the synthesis tower tank 1. The upper annular header 3 is communicated with the cold side outlet of the sludge pre-cooling plate heat exchanger 31 to introduce the low-temperature ethylene glycol coolant, and the lower annular header 4 is communicated with the return branch of the sludge pre-cooling plate heat exchanger 31. A CO2 gas inlet main pipe 5 is fixed at the top end of the synthesis tower tank 1, a sludge feed port 6 is opened on the middle side wall of the synthesis tower tank 1, a conical aggregate hopper 7 is fixed at the bottom end of the synthesis tower tank 1, and the conical surface of the conical aggregate hopper 7 shrinks downward for collecting the hydrate-containing sludge.

[0021] like Figure 3 As shown, a wall cleaning drive assembly is installed at the center of the top of the synthesis tower tank 1. The wall cleaning drive assembly includes a vertical main shaft 13, a magnetic coupling actuator, four sets of horizontal spokes 14, and a flexible spiral scraper 15. The vertical main shaft 13 is arranged along the central axis of the synthesis tower tank 1 and extends through the entire height of the tank's interior. The vertical main shaft 13 is radially and axially supported by a main shaft bearing 35 fixed to the inner wall of the synthesis tower tank 1. The magnetic coupling actuator is located in a localized area of ​​the pressure-bearing cavity at the top of the synthesis tower tank 1 and includes an outer magnetic rotor 10, a magnetic coupling isolation sleeve 11, and an inner magnetic rotor 12. The magnetic coupling isolation sleeve 11 is fixed to the pressure-bearing cavity structure at the top of the synthesis tower tank 1 and forms a pressure boundary wall. The inner magnetic rotor 12 is located inside the magnetic coupling isolation sleeve 11 and is connected to the top of the vertical main shaft 13 via a spline. The outer magnetic rotor 10 is located outside the magnetic coupling isolation sleeve 11 and surrounds the outer wall of the magnetic coupling isolation sleeve 11. It is driven by a geared motor 9 fixed to the tower top flange support 8. The tower top flange support 8 is fixed to the outer side of the top flange face of the synthesis tower tank 1. The geared motor 9 is fixed to the tower top flange support 8. The output shaft axis of the geared motor 9 points vertically downwards into the tank and is fixedly connected to the outer magnetic rotor 10. When the output shaft of the geared motor 9 rotates, it drives the outer magnetic rotor 10 to rotate synchronously. The magnetic torque passes through the magnetic coupling isolation sleeve 11 and is transmitted to the inner magnetic rotor 12. The inner magnetic rotor 12 drives the vertical main shaft 13 to rotate around its own axis via a spline. Four sets of horizontal spokes 14 are evenly distributed and fixed at different height positions along the height direction on the vertical main shaft 13. Each set of horizontal spokes 14 extends radially outwards from the vertical main shaft 13 to the annular area where each column of vertical spiral heat exchange tube bundle 2 is located. Each horizontal spoke 14 has a flexible spiral scraper 15 fixed to its outer end. The flexible spiral scraper 15 wraps around the outer wall of the corresponding vertical spiral heat exchange tube bundle 2 in a spiral shape and maintains light pressure contact with the outer wall of the vertical spiral heat exchange tube bundle 2. Figure 4 As shown, it should be noted that the six rows of vertical spiral heat exchange tube bundles 2 are evenly distributed in the same annular area along the circumference. When the four sets of horizontal spokes 14 revolve around the central axis of the synthesis tower tank 1 with the vertical main axis 13, they sweep past each row of vertical spiral heat exchange tube bundles 2 in sequence. When the flexible spiral scraper 15 at the outer end of each horizontal spoke 14 passes through each row of vertical spiral heat exchange tube bundles 2, it contacts the outer wall of the vertical spiral heat exchange tube bundle 2 and slides relative to it along the spiral direction, thus completing the cleaning of the outer wall surface of each row of vertical spiral heat exchange tube bundles 2.

[0022] In some embodiments, the flexible spiral scraper 15 is a flexible polytetrafluoroethylene strip. The cross-section of the flexible polytetrafluoroethylene strip is arc-shaped to fit the cylindrical outer wall of the vertical spiral heat exchange tube bundle 2. The strip is arranged in a spiral winding manner along the axial direction of the vertical spiral heat exchange tube bundle 2. One long side of the strip is fixed to the outer end of the horizontal spoke 14, and the arc surface of the other long side forms a sliding friction pair with the outer wall of the vertical spiral heat exchange tube bundle 2.

[0023] like Figure 6 As shown, furthermore, in order to accommodate the spacing deviations between the vertical spiral heat exchange tube bundles 2 and the minor protrusions on the surface of the vertical spiral heat exchange tube bundles 2 during rotation without rigid jamming, an elastic connector is used to connect the outer end of the horizontal spokes 14 to the flexible spiral scraper 15. The elastic connector is a radially arranged compression spring 16. One end of the compression spring 16 is fixed to the inner wall of the sleeve at the outer end of the horizontal spokes 14, and the other end abuts against the fixing seat of the flexible spiral scraper 15. The compression spring 16 provides pre-tightening pressure in the radial direction so that the flexible spiral scraper 15 always adheres to the outer wall surface of the vertical spiral heat exchange tube bundle 2. When it encounters wall deposits or surface irregularities, the compression spring 16 is compressed and elastically releases. After the deposits pass, the compression spring 16 returns to its original length, allowing the flexible spiral scraper 15 to re-adhere to the outer wall surface of the vertical spiral heat exchange tube bundle 2.

[0024] like Figure 5 As shown, a pressure self-balancing feed column lock is installed between the bottom of the hydrate synthesis tower and the top of the hydrate decomposition tower, including a feed riser 18, a discharge riser 19, a U-shaped connecting section 20, a gate assembly, and an external support 17 for the feed column lock. The external support 17 provides structural support around the outside of the feed riser 18, the discharge riser 19, and the U-shaped connecting section 20. The feed riser 18 extends vertically downward from the outlet of the conical hopper 7 of the hydrate synthesis tower and is fixed to the external support 17 of the feed column lock via a flange. The axis of the feed riser 18 is collinear with the axis of the hydrate synthesis tower tank 1. The discharge riser 19 is located on one side of the hydrate decomposition tower, extends vertically upward to the feed inlet at the top of the hydrate decomposition tower, and is fixed to the external support 17 of the feed column lock via a flange. The axis of the discharge riser 19 is aligned with the axis of the decomposition tower body 27 of the hydrate decomposition tower. The U-shaped connecting section 20 is located at the lowest point between the bottom ends of the feed riser 18 and the discharge riser 19. It forms a U-shape in the vertical plane containing the two risers, connecting their bottom ends. The two ends of the U-shaped connecting section 20 are welded to the bottom ends of the feed riser 18 and the discharge riser 19, respectively. The middle part of the U-shaped connecting section 20 is fixed to the external support 17 of the material column lock via a bracket. Figure 2 As shown, the vertical length of the feed riser 18 is matched to the sludge density and the pressure difference between the two towers, so that the static pressure head of the sludge column in the feed riser 18 balances the working pressure of the hydrate synthesis tower. According to the formula, where is the pressure difference between the two towers (approximately 0.3 MPa), is the sludge density (approximately 1300 kg / m³), is the gravitational acceleration (9.8 m / s²), and is the required riser height, the calculated height of the feed riser 18 is approximately 23 m.

[0025] Continue reading Figure 5The gate assembly includes an upper gate 21 at the feed end, an upper gate 23 at the discharge end, and two lower gates 25. The upper gate 21 at the feed end is located at the top of the feed riser 18. A gate seat hole is provided in the top wall of the feed riser 18. The upper gate 21 is embedded in the guide groove of the gate seat hole and can move linearly in a horizontal direction. The cylinder body of the upper gate cylinder 22 at the feed end is fixed to the outer side of the top of the feed riser 18. The piston rod of the upper gate cylinder 22 is connected to the upper gate 21 at the feed end. When the piston rod extends, it pushes the upper gate 21 into the gate seat hole to close it. When the piston rod retracts, it pulls the upper gate 21 out to fully open it. The upper gate 23 at the discharge end is located at the top of the discharge riser 19. The structure and installation method of the upper gate 23 at the discharge end are the same as those of the upper gate 21 at the feed end. The upper gate cylinder 24 at the discharge end is fixed to the outer side of the top of the discharge riser 19, and the piston rod of the upper gate cylinder 24 at the discharge end is connected to the upper gate 23 at the discharge end. Two lower gates 25 are located on both sides of the U-shaped connecting section 20. Gate seat holes are opened on both sides of the pipe wall of the U-shaped connecting section 20, and each lower gate 25 is embedded in the guide groove of the corresponding gate seat hole. Two lower gate cylinders 26 are fixed to the outer sides of the U-shaped connecting section 20 of the material column lock external support 17, and the piston rod of each lower gate cylinder 26 is connected to the corresponding lower gate 25. The air supply pipes of all gate cylinders are connected along the external support 17 of the material column lock and do not pass through the pressure-bearing wall. Under normal operating conditions, all gates are in the fully open position and do not participate in sealing the material flow path.

[0026] It should be noted that when each lower gate 25 is embedded in the guide groove of the corresponding gate seat hole in the disconnected state, each lower gate 25 is sealed and fitted with the corresponding gate seat hole.

[0027] In some embodiments, the guide groove of each gate seat hole is a rectangular cross-section slide groove, and a sliding pair is formed between the gate plate body and the rectangular cross-section slide groove. After the gate is inserted, its end face fits against the opposite side wall of the gate seat hole to achieve static sealing.

[0028] The hydrate decomposition tower is an atmospheric pressure vessel, such as... Figure 1 As shown, the axis of the decomposition tower body 27 of the hydrate decomposition tower is arranged vertically and is located on one side of the synthesis tower tank 1 of the hydrate synthesis tower. (Continue reading...) Figure 5 The inner wall of the decomposition tower body 27 is fixed with stepped distribution plates 28. These plates are arranged in a staggered manner along the height direction, allowing hydrate-containing sludge to fall gradually from the top of the tower. A conical discharge port 29 is fixed at the bottom of the decomposition tower body 27. The conical discharge port 29 tapers downwards to collect the dewatered sludge. A top vent pipe 30 is fixed at the top of the decomposition tower body 27, connecting to the hot-side inlet of the sludge pre-cooling plate heat exchanger 31. The outlet of the conical discharge port 29 is connected to an external filter press via a screw pump.

[0029] Continue reading Figure 1 The hot-side inlet of the sludge precooling plate heat exchanger 31 is connected to the top outlet pipe 30 of the hydrate decomposition tower, and the hot-side outlet is connected to the suction inlet of the gas recirculation compressor 32. The cold-side inlet is connected to the sludge feed pipeline via a pipe, and the cold-side outlet is connected to the sludge feed inlet 6 of the hydrate synthesis tower via a pipe. The low-temperature gas released from the hydrate decomposition tower flows through the hot-side channel of the sludge precooling plate heat exchanger 31, and the sludge feed flows through the cold-side channel of the sludge precooling plate heat exchanger 31, with the two exchanging heat in countercurrent flow. The suction inlet of the gas recirculation compressor 32 is connected to the hot-side outlet of the sludge precooling plate heat exchanger 31, and the exhaust port of the gas recirculation compressor 32 is connected to the inlet of the condenser 33. The outlet of the condenser 33 is connected to the inlet of the dryer 34, and the outlet of the dryer 34 is connected to the CO2 inlet main pipe 5 of the hydrate synthesis tower, thus forming a closed-loop gas circulation circuit.

[0030] Working principle After being cooled by counter-current heat exchange between the dredged sludge and the gas from the hydrate decomposition tower via the sludge pre-cooling plate heat exchanger 31, it is injected into the synthesis tower tank 1 through the sludge feed inlet 6 in the middle of the hydrate synthesis tower. High pressure enters the tank through the CO2 inlet manifold 5, where it reacts with the free water in the sludge to form hydrates under low temperature and high pressure. The coolant circulates continuously within the vertical spiral heat exchange tube bundle 2 to provide a cooling source.

[0031] Driven by a magnetic coupling actuator, the vertical main shaft 13 rotates around its own axis at a speed of 3 to 5 rpm, driving four sets of horizontal spokes 14 and flexible spiral scrapers 15 to rotate at a low speed around the central axis of the synthesis tower tank 1. The flexible spiral scrapers 15 at the outer ends of the horizontal spokes 14 pass through each row of vertical spiral heat exchange tube bundles 2 in sequence. When passing through each row of vertical spiral heat exchange tube bundles 2, they contact the outer wall of the vertical spiral heat exchange tube bundles 2 and slide relative to each other along the spiral direction. This peels off the humic colloidal film and initial hydrate crystals adhering to the outer wall of the vertical spiral heat exchange tube bundles 2 from the wall and pushes them into the main slurry in the tank. The peeled hydrate microcrystals disperse in the sludge body as heterogeneous nucleation sites, accelerating the hydrate crystallization process of the surrounding free water.

[0032] Hydrate-containing sludge, along with sand particles, flows into the conical collection hopper 7 at the bottom of the tank under gravity, and continuously flows into the feed riser 18 from the outlet of the conical collection hopper 7. The sludge gradually accumulates in the feed riser 18, forming a vertical column. The static pressure head generated by the weight of the vertical column automatically balances the pressure difference between the hydrate synthesis tower and the hydrate decomposition tower, achieving continuous material transport from the high-pressure side to the atmospheric pressure side. Sand-containing particles flow along with the main body of sludge in the feed riser 18, enter the discharge riser 19 through the U-shaped connecting section 20, and are discharged into the hydrate decomposition tower from the top of the discharge riser 19. Throughout the entire process, the sand particles remain suspended within the sludge slurry, flowing within the pipe without contacting any gate sealing surface.

[0033] After entering the hydrate decomposition tower from the top of the discharge riser 19, the sludge falls step by step onto the stepped distribution plate 28. Under normal pressure, the hydrate decomposes, releasing low-temperature gas and removing water, thus reducing the sludge's moisture content. The released low-temperature gas exits from the top outlet pipe 30, and after exchanging heat with the sludge to be fed through the hot side channel of the sludge pre-cooling plate heat exchanger 31, its temperature rises. It is then drawn in by the gas circulation compressor 32 and compressed to the working pressure of the hydrate synthesis tower. After being cooled by the condenser 33 and having residual moisture removed by the dryer 34, it returns to the CO2 inlet manifold 5 of the hydrate synthesis tower, completing the closed-loop gas circulation. After dewatering, the sludge is pumped from the conical discharge port 29 of the hydrate decomposition tower to a filter press for further processing via a screw pump.

[0034] In some embodiments, the gate operation steps under maintenance conditions are as follows: First, drive the upper gate cylinder 22 at the feed end to extend the piston rod of the upper gate cylinder 22 at the feed end, pushing the upper gate 21 at the feed end into the gate seat hole to close, isolating the feed riser 18 from the hydrate synthesis tower; then drive the upper gate cylinder 24 at the discharge end and the two lower gate cylinders 26 to sequentially close the upper gate 23 at the discharge end and the two lower gates 25 at the discharge end, isolating the discharge riser 19 from the hydrate decomposition tower and sealing both sides of the U-shaped connecting section 20, achieving complete isolation of the pressure self-balancing material column lock. The gate sealing surface only bears the static sealing task in the closed state and does not participate in the flow process of sand-containing materials.

[0035] Technical effects of this embodiment Driven by the vertical main shaft 13, the flexible spiral scraper 15 rotates around the central axis of the synthesis tower tank 1 along with the horizontal spokes 14. It sequentially passes through each row of vertical spiral heat exchange tube bundles 2 and performs a spiral sweeping motion along the outer wall of the vertical spiral heat exchange tube bundles 2, peeling off the humic colloidal film and initially attached hydrate crystals from the cold wall surface, ensuring that the outer wall surface of the vertical spiral heat exchange tube bundles 2 remains clean. Therefore, the heat transfer coefficient of the vertical spiral heat exchange tube bundles 2 does not decrease with operating time, and the cooling capacity can be continuously and effectively transferred to the free water in the sludge, ensuring stable and rapid crystallization of hydrates in a high-viscosity humic environment. The peeled hydrate microcrystals disperse in the main slurry, serving as heterogeneous nucleation sites to further promote crystallization, ensuring that the hydrate production meets the material supply requirements for continuous operation. The magnetically coupled actuator transmits power to the vertical main shaft 13 within the pressure chamber through the magnetically coupled isolation sleeve 11, avoiding the risk of leakage of the dynamic seal under high pressure when the rotating shaft passes through the pressure wall surface, thus ensuring the long-term sealing reliability of the hydrate synthesis tower.

[0036] The pressure-balanced feed column lock utilizes the static pressure head generated by the weight of the sludge column within the feed riser 18 to counteract the pressure difference between the two towers, achieving continuous material transport from the high-pressure side to the atmospheric-pressure side. Sand-containing particles remain suspended within the sludge slurry, flowing within the feed riser 18 and the U-shaped connecting section 20, without contacting any gate sealing surface. Therefore, abrasive wear of the sealing surface by hard sand particles is avoided, and the gate sealing surface only bears the static sealing task during maintenance closure; its sealing performance does not degrade due to the long-term passage of sand-containing materials. Continuous feed column transport replaces intermittent valve unloading, eliminating the risk of sludge freezing and accumulating in the valve cavity during intermittent unloading, while simultaneously maintaining stable suction pressure on the gas recirculation compressor 32.

[0037] The combined effect of these two mechanisms ensures a clean hydrate synthesis tower wall, guaranteeing sufficient hydrate production and providing enough hydrate-containing material for the hydrate decomposition tower to release cooling energy. The pressure self-balancing feed column lock maintains a stable pressure difference between the two towers, preventing high-pressure leakage due to seal failure. Therefore, the overall closed-loop cascade cold energy recovery cycle can operate steadily for a long time under sand-containing, high-viscosity conditions.

[0038] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A sludge treatment energy recycling device based on crystallization decomposition, characterized in that, include: The synthesis tower tank (1) is a vertical pressure tank, and multiple vertical spiral heat exchange tube bundles (2) are evenly distributed in the circumference of the synthesis tower tank (1). The wall cleaning drive assembly includes a vertical main shaft (13), a magnetically coupled driver, horizontal spokes (14), and a flexible spiral scraper (15). The vertical main shaft (13) is arranged along the central axis of the synthesis tower tank (1). The horizontal spokes (14) are fixed to the vertical main shaft (13) and extend radially. The flexible spiral scraper (15) is fixed to the outer end of the horizontal spokes (14) and contacts the outer wall of the vertical spiral heat exchange tube bundle (2). The pressure self-balancing material column lock includes a feed riser (18), a discharge riser (19) and a U-shaped connecting section (20). The feed riser (18) extends downward from the bottom of the synthesis tower tank (1), and the discharge riser (19) extends upward to the atmospheric pressure decomposition tower (27). The U-shaped connecting section (20) connects the bottom ends of the two risers. The static pressure head of the sludge material column in the feed riser (18) balances the pressure difference between the two towers.

2. The sludge treatment energy recycling device based on crystallization decomposition according to claim 1, characterized in that, The magnetic coupling actuator includes an outer magnetic rotor (10), a magnetic coupling isolation sleeve (11), and an inner magnetic rotor (12). The magnetic coupling isolation sleeve (11) is fixed to the top of the synthesis tower tank (1) and forms a pressure boundary wall. The inner magnetic rotor (12) is located inside the magnetic coupling isolation sleeve (11) and is connected to the top of the vertical main shaft (13) via a spline. The outer magnetic rotor (10) is located outside the magnetic coupling isolation sleeve (11) and surrounds the outer wall of the magnetic coupling isolation sleeve (11). The vertical main shaft (13) is radially and axially supported by a main shaft bearing (35) fixed to the inner wall of the synthesis tower tank (1).

3. The sludge treatment energy recycling device based on crystallization decomposition according to claim 2, characterized in that, A tower top flange bracket (8) is fixedly installed on the outer side of the top flange face of the synthesis tower tank (1). A geared motor (9) is fixed to the tower top flange bracket (8). The output shaft of the geared motor (9) points downward in the vertical direction into the tank and is fixedly connected to the outer magnetic rotor (10).

4. The sludge treatment energy recycling device based on crystallization decomposition according to claim 1, characterized in that, The flexible spiral scraper (15) is a polytetrafluoroethylene strip. The cross-section of the strip is arc-shaped to fit the cylindrical outer wall of the vertical spiral heat exchange tube bundle (2). The strip is arranged in a spiral winding manner along the axial direction of the vertical spiral heat exchange tube bundle (2). One long side of the strip is fixed to the outer end of the horizontal spoke (14), and the arc surface of the other long side forms a sliding friction pair with the outer wall of the vertical spiral heat exchange tube bundle (2).

5. The sludge treatment energy recycling device based on crystallization decomposition according to claim 1, characterized in that, A compression spring (16) is provided between the outer end of the horizontal spoke (14) and the flexible spiral scraper (15) arranged in a radial direction. One end of the compression spring (16) is fixed to the inner wall of the sleeve at the outer end of the horizontal spoke (14), and the other end abuts against the fixing seat of the flexible spiral scraper (15). The compression spring (16) provides pre-tightening pressure in a radial direction so that the flexible spiral scraper (15) fits against the outer wall of the vertical spiral heat exchange tube bundle (2).

6. The sludge treatment energy recycling device based on crystallization decomposition according to claim 1, characterized in that, The top ends of each vertical spiral heat exchange tube bundle (2) are connected to the upper annular manifold (3), and the bottom ends of each vertical spiral heat exchange tube bundle (2) are connected to the lower annular manifold (4). The upper annular manifold (3) and the lower annular manifold (4) are respectively fixed to the upper and lower parts of the inner cavity of the synthesis tower tank (1) and surround the central axis of the synthesis tower tank (1). The upper annular manifold (3) is used to introduce the refrigerant, and the lower annular manifold (4) is used for the refrigerant reflux. The top end of the synthesis tower tank (1) is fixed with a CO2 inlet manifold (5), and a sludge inlet (6) is opened on the middle side wall of the synthesis tower tank (1). The bottom end of the synthesis tower tank (1) is fixed with a conical hopper (7) for collecting hydrated sludge. The outlet of the conical hopper (7) is connected to the top end of the feed riser (18).

7. The sludge treatment energy recycling device based on crystallization decomposition according to claim 1, characterized in that, The pressure self-balancing material column lock also includes a gate assembly and an external support (17) for the material column lock. The external support (17) of the material column lock provides structural support around the outside of the feed riser (18), the discharge riser (19) and the U-shaped connecting section (20). The gate assembly includes an upper gate (21) at the feed end, an upper gate (23) at the discharge end and two lower gates (25). The upper gate (21) at the feed end is located at the top of the feed riser (18) and is embedded in the guide groove of the gate seat hole in the pipe wall, moving in a straight line in the horizontal direction. The upper gate (23) at the discharge end is located at the top of the discharge riser (19) and has the same structure as the upper gate (21) at the feed end. The two lower gates (25) are located in the guide grooves of the gate seat holes on both sides of the U-shaped connecting section (20). Under normal operating conditions, all gates are in the fully open position.

8. The sludge treatment energy recycling device based on crystallization decomposition according to claim 7, characterized in that, The cylinder body of the upper gate cylinder (22) at the feeding end is fixed to the outer side of the top of the feeding riser (18) of the external support (17) of the material column lock. The piston rod of the upper gate cylinder (22) at the feeding end is connected to the upper gate (21) at the feeding end. The cylinder body of the upper gate cylinder (24) at the discharging end is fixed to the outer side of the top of the discharging riser (19) of the external support (17) of the material column lock. The piston rod of the upper gate cylinder (24) at the discharging end is connected to the upper gate (23) at the discharging end. The cylinder bodies of the two lower gate cylinders (26) are respectively fixed to the outer sides of the U-shaped connecting section (20) of the external support (17) of the material column lock. The piston rod of each lower gate cylinder (26) is connected to the corresponding lower gate (25).

9. The sludge treatment energy recycling device based on crystallization decomposition according to claim 1, characterized in that, The inner wall of the decomposition tower body (27) is fixed with stepped material distribution plates (28), and each step of the stepped material distribution plates (28) is arranged in a staggered manner along the height direction; a conical discharge port (29) is fixed at the bottom of the decomposition tower body (27), and the conical discharge port (29) is tapered downward to collect the sludge after dewatering. The top of the decomposition tower body (27) is fixed with a tower top outlet pipe (30).

10. The sludge treatment energy recycling device based on crystallization decomposition according to claim 9, characterized in that, It also includes a precooling plate heat exchanger (31), a gas circulation compressor (32), a condenser (33), and a dryer (34); the top gas outlet pipe (30) is connected to the hot side inlet of the precooling plate heat exchanger (31), the hot side outlet of the precooling plate heat exchanger (31) is connected to the suction port of the gas circulation compressor (32), and the exhaust port of the gas circulation compressor (32) is connected to the CO2 inlet manifold (5) of the synthesis tower tank (1) in sequence through the condenser (33) and the dryer (34) to form a closed loop of CO2 gas circulation; the cold side inlet of the precooling plate heat exchanger (31) is connected to the sludge pipeline to be fed, and the cold side outlet of the precooling plate heat exchanger (31) is connected to the sludge feed port (6) of the synthesis tower tank (1).

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