Urea reaction heat energy recovery system

Abstract

The invention relates to a urea reaction heat energy recovery system, and belongs to the technical field of heat energy recovery systems. The energy-saving environment-friendly boiler comprises a boiler body, an air outlet pipeline is connected to the boiler body, a heat recovery box is connected to the tail end of the air outlet pipeline, an exhaust pipeline is connected to the heat recovery box, a heat exchange assembly is arranged in the heat recovery box, and the heat exchange assembly comprises a plurality of heat exchange pipelines which are arranged left and right at intervals; the heat exchange pipeline comprises a plurality of horizontal pipe sections which are arranged at intervals in the vertical direction and extend in the front-back direction, a vertical pipe section used for communicating the two horizontal pipe sections is connected between the ends of any two horizontal pipe sections which are adjacent in the vertical direction, and a first scraping plate is inserted into each horizontal pipe section in a matched mode. The left side pipe wall and the right side pipe wall of each vertical pipe section are both in an arc shape and are kept coaxial, a second scraping plate is arranged in each vertical pipe section, and the second scraping plates are rotationally installed in the vertical pipe sections around the axes of the arc-shaped side walls. Scale on the inner side wall of the spiral heat exchange pipeline can be effectively removed, and the influence on the heat exchange efficiency is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of heat energy recovery systems, and in particular to a urea reaction heat energy recovery system. Background Art

[0002] The pyrolysis reaction of urea refers to the process of urea decomposing into ammonia and carbon dioxide under high temperature conditions. This reaction has important applications in industry, such as the production of ammonia and synthetic ammonia. The pyrolysis reaction of urea usually needs to rely on a urea pyrolysis furnace. The urea pyrolysis furnace generally includes a furnace body, a heating system, a feeding system, a gas collection system and other structures. When in use, urea is fed into the pyrolysis furnace through the feeding system, and begins to decompose under the high temperature in the furnace body. After pyrolysis, ammonia, carbon dioxide and other gases are generated. These gases are collected and transported to downstream processes through pipelines for further processing or direct use.

[0003] Ammonia and carbon dioxide discharged from the urea pyrolysis furnace generally carry a large amount of heat. In order to avoid heat waste, the heat in the exhaust gas can be recovered through devices such as heat exchangers. The collected heat can be used to preheat the feed, heat other media or generate steam, which can improve the energy efficiency of the entire system.

[0004] In the prior art, heat exchange structures are usually used to recover heat from high-temperature gases, among which a shell and tube heat exchanger is a common heat exchanger. The shell and tube heat exchanger is generally composed of an outer shell and internal pipes, and two fluids flow in the shell and the tubes respectively to achieve heat exchange. For example, the patent with the authorization announcement number CN208887366U discloses a flue gas recovery device for an aluminum smelting furnace, which includes a smelting furnace, a water tank, a magnetic adsorption box, a dust removal box, a harmful gas treatment pool and a slaked lime pool. A heat-conducting water pipe is wound around the furnace wall of the smelting furnace, and a plurality of vertical copper rods are arranged in the water tank, and heat-conducting pipes are wound around the copper rods in sequence. When in use, water circulates in the heat-conducting water pipe and the heat-conducting water pipe, and the water in the heat-conducting water pipe absorbs the waste heat of the smelting furnace to increase its temperature, and transfers the temperature to the water in the water tank.

[0005] Hot water circulates in the heat transfer pipe for a long time, and scale is easily precipitated in the water. Although the water entering the pipe can be softened to reduce the formation of scale, after long-term use, some scale will inevitably adhere to the inner wall of the pipe.

[0006] In the actual production process, considering factors such as optimizing space utilization and increasing heat exchange area, the heat transfer pipe is generally made into a spiral serpentine structure. The spiral pipe has a unique shape and many corners. If scale accumulates on its inner wall, it is difficult for tools to reach into the pipe, and the scale attached to the inner wall of the spiral pipe is difficult to clean, which will cause the pipe wall thickness to increase and affect the heat exchange efficiency. Summary of the invention

[0007] The present invention provides a urea reaction heat energy recovery system to solve the technical problem that scale attached to the inner wall of a spiral heat exchange pipe in the heat recovery system in the prior art is difficult to remove, and after long-term use, the scale thickens, resulting in increased pipe wall thickness and reduced heat exchange efficiency.

[0008] In order to solve the above problems, the present invention provides a urea reaction heat energy recovery system adopts the following technical solutions:

[0009] A urea reaction heat energy recovery system comprises a furnace body, an air outlet pipe is connected to the furnace body, a heat recovery box is connected to the end of the air outlet pipe, an exhaust pipe is connected to the heat recovery box, a heat exchange component is arranged in the heat recovery box, and the heat exchange component comprises a plurality of heat exchange pipes arranged at intervals on the left and right;

[0010] The heat exchange pipe comprises a plurality of horizontal pipe sections which are arranged at intervals in the upper and lower parts and extend in the front-to-back direction. A vertical pipe section for connecting the two horizontal pipe sections is connected between the ends of any two vertically adjacent horizontal pipe sections. Any two vertically adjacent vertical pipe sections are arranged at the front and rear ends of the horizontal pipe section between the two vertical pipe sections. The top opening of the heat exchange pipe is the pipe inlet, and the bottom opening is the pipe outlet.

[0011] Each horizontal pipe section is adapted to be inserted with a scraper 1, which can slide back and forth in the horizontal pipe section to scrape off the scale on the inner wall of the horizontal pipe section;

[0012] The left and right pipe walls of the vertical pipe section are both arc-shaped and coaxial, and their axes extend in the front-to-back direction. A scraper 2 is provided in each vertical pipe section. The width dimension of the scraper 2 in the front-to-back direction is matched with the inner diameter dimension of the vertical pipe section in the front-to-back direction. The scraper 2 is installed in the vertical pipe section and rotates around the axis of the arc-shaped side wall. During the rotation of the scraper 2, the scale on the inner walls of the vertical pipe section can be scraped off.

[0013] By adopting the above technical solution, if scale is generated on the inner wall of the heat exchange pipe, the scraper 1 slides back and forth in the horizontal pipe section to scrape off the scale on the horizontal pipe section, and the scraper 2 rotates in the vertical pipe section. Since the left and right side walls of the vertical pipe section are arc-shaped side walls, the scraper 2 can contact the left and right side walls of the vertical pipe section during the rotation process, thereby scraping off the scale on the inner wall of the vertical pipe section. The arrangement of the scraper 1 and the scraper 2 can effectively clean the scale on the inner wall of the circling heat exchange pipe, and the cleaning process is more convenient. When scale appears on the inner wall of the heat exchange pipe, it can be cleaned in time to avoid the accumulation of scale affecting the heat exchange efficiency.

[0014] Furthermore, a pull rod extending forward and backward is provided on scraper one, and the end of the pull rod facing away from scraper one is passed through the outside of the heat exchange pipe. When the pull rod is pulled forward and backward, it can drive scraper one to slide forward and backward in the horizontal pipe section to scrape off scale.

[0015] By adopting the above technical solution, the pull rod is pulled to move in the front-rear direction, so that the scraper plate 1 can be driven to slide back and forth in the horizontal pipe section. The method of driving the scraper plate 1 to slide is simple and the structure is simple.

[0016] Furthermore, a transmission screw extending forward and backward is spirally installed in the scraper plate 2. When the transmission screw is pulled forward and backward, it can drive the scraper plate 2 to rotate in the vertical pipe section to scrape off the scale.

[0017] By adopting the above technical solution, the second scraper can be driven to rotate by pulling the transmission screw forward and backward, and the method of driving the second scraper to rotate is simple and the structure is simple. The forward and backward movement of the transmission screw is converted into the rotation of the second scraper. The extension direction and movement direction of the transmission screw are consistent with the above pull rod. The movement mode of the transmission screw and the pull rod is more unified. When arranging the power element, one power element can drive the two to move synchronously.

[0018] Furthermore, connector 1 and connector 2 are respectively provided on the front and rear sides of the heat recovery box. The transmission screws inserted in the scraper 2 in each vertical pipe section on the front side are all connected to connector 1, and the pull rods inserted in each adjacent horizontal pipe section above each vertical pipe section on the front side are also connected to connector 1. The remaining pull rods and transmission screws are all connected to connector 2. Connector 1 and connector 2 can both move back and forth in the front and rear directions to drive scraper 1 to slide back and forth and drive scraper 2 to rotate to scrape off scale in the heat exchange pipe.

[0019] By adopting the above technical solution, when the connecting member 1 and the connecting member 2 are pulled to move forward and backward, the corresponding multiple pull rods and multiple transmission screws are driven to move forward and backward synchronously. When in use, it is only necessary to drive the connecting member 1 and the connecting member 2 to move forward and backward, and there is no need to drive each pull rod and transmission screw to move forward and backward separately, which can save power components.

[0020] Furthermore, the scraper 1 includes a plate frame and a plurality of movable plates, the plurality of movable plates are evenly distributed on the plate frame around a central axis extending forward and backward, and each movable plate is movably mounted on the plate frame. The direction in which the scraper 1 moves in the inner cavity of the heat exchange pipe toward the bottom outlet of the heat exchange pipe is defined as a first moving direction, and the opposite direction is defined as a second moving direction. When the scraper 1 moves along the first moving direction, each movable plate can move away from the center of the plate frame and be pressed against each pipe wall of the horizontal pipe section respectively. When the scraper 1 moves along the second moving direction, each movable plate can gather toward the center of the plate frame to be loosened from the pipe wall of the corresponding horizontal pipe section.

[0021] By adopting the above technical solution, when the scraper moves along the first moving direction, each movable plate can be pressed against the pipe wall of the horizontal pipe section, so that the scraper can scrape off the scale when it moves along the first moving direction. During the process of scraping off the scale, the moving direction of the scraper is consistent with the flow direction of the water flow. The scraper is assisted by the thrust of the water flow, and the process of scraping off the scale is easier. The direction in which the scale is scraped off is consistent with the direction of the water flow. The scale that is scraped off halfway is more easily dropped from the pipe wall by the thrust of the water flow, and the scraped scale flows directly along the direction of the water flow toward the outlet of the heat exchange pipe, which has a better effect of discharging the scale.

[0022] When the scraper 1 moves along the second moving direction, it is hindered by the water flow and has a large moving resistance. At this time, each movable plate is loosened from the corresponding pipe wall, the friction between the movable plate and the pipe wall is reduced, and the scale is not scraped off, and the resistance from the scale is also reduced, which can relatively reduce the resistance of the scraper 1 when moving along the second moving direction. If the scraper 1 is manually driven to move along the second moving direction, the moving process will be more labor-saving. If it is driven by a driving element, the load on the driving element is smaller, which can extend the service life of the driving element.

[0023] Furthermore, a through hole running through the front and back is provided in the middle of the plate frame, and each movable plate is connected with a support rod, which is elastically slidably installed on the plate frame along a direction perpendicular to the axis of the through hole, and one end of each support rod facing away from the movable plate extends into the through hole, and the end of the support rod extending into the through hole is provided with a sliding slope, and the sliding slopes approach each other along a first moving direction. A driving block is provided in the through hole, and the driving block is located in the area surrounded by the sliding slopes. When the driving block moves along the first moving direction, it can push each support rod away from the center of the plate frame through the sliding slope, so as to drive the movable plate away from the center of the plate frame and press it against the corresponding pipe wall in the horizontal pipe section, and the pull rod is connected to the driving block.

[0024] By adopting the above technical solution, when the pull rod is pulled to move along the first moving direction, the driving block can be driven to move along the first moving direction. The driving block can drive the plate frame to move along the first moving direction, and can push each support rod away from the center of the plate frame by pushing the inclined surface, so as to drive each movable plate to be pressed against the pipe wall of the horizontal pipe section, so that when the scraper moves along the first moving direction, the movable plate can be pressed against the pipe wall of the horizontal pipe section. The structure is simple and ingenious, and it is easy to assemble.

[0025] Furthermore, a stop plate is provided on the plate frame, which is located in front of the driving block in the second moving direction. The stop plate and the driving block stop each other front and back. When the driving block moves along the second moving direction, it can push the stop plate and drive the scraper to move along the second moving direction.

[0026] By adopting the above technical solution, since the plate frame is provided with a stop plate that stops the driving block in front and behind, when the pull rod drives the driving block to move along the second moving direction, the driving block can push the stop plate, thereby driving the scraper to move along the second moving direction.

[0027] Furthermore, the top inlet of each heat exchange pipe is connected to an inlet main pipe extending left and right, and the bottom outlet of each heat exchange pipe is connected to an outlet main pipe extending left and right. A low-temperature water tank and a high-temperature water tank are arranged below the heat recovery tank. One end of the inlet main pipe is closed, and the other end is connected to the low-temperature water tank. One end of the outlet main pipe is closed, and the other end is connected to the high-temperature water tank. A filter element is arranged in the outlet main pipe, and a pump body is arranged between the inlet main pipe and the water tank. The pump body is used to pump the water in the low-temperature water tank into each heat exchange pipe, and force the heated hot water in the heat exchange pipe to flow into the high-temperature water tank.

[0028] By adopting the above technical solution, the pump body allows the water in the low-temperature water tank to flow into the high-temperature water tank after passing through the heat exchange pipe and being heated. The scale scraped off by scrapers one and two can be carried by the water flow and discharged from the outlet of the heat exchange pipe to the outlet main pipe. The filter element in the outlet main pipe can block the scale and prevent it from entering the high-temperature water tank.

[0029] The beneficial effect of a urea reaction heat recovery system provided by the present invention is that the heat exchange pipe can recycle the heat in the high-temperature gas generated by the urea pyrolysis reaction, which is more energy-saving and environmentally friendly. The heat exchange pipe is set to a structure composed of a horizontal pipe section and a vertical pipe section, and the left pipe wall and the right pipe wall of the vertical pipe section are set to an arc shape. At the same time, a scraper 1 that can slide back and forth is set in the horizontal pipe section, and a scraper 2 that can rotate is set in the vertical pipe section. The scale in the heat exchange pipe can be effectively removed during the forward and backward movement of the scraper 1 and the rotation of the scraper 2. The scale on the inner wall of the heat exchange pipe can be removed in time to avoid the accumulation of scale and the increase of the pipe wall thickness, which leads to a decrease in heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0031] Figure 1 A schematic diagram of the overall structure of a urea reaction heat energy recovery system provided by the present invention;

[0032] Figure 2 A schematic structural diagram of a heat recovery box in a urea reaction heat recovery system provided by the present invention after being cut open;

[0033] Figure 3A schematic diagram of the three-dimensional structure of a heat exchange component in a urea reaction heat energy recovery system provided by the present invention;

[0034] Figure 4 A side view of a heat exchange component in a urea reaction heat energy recovery system provided by the present invention;

[0035] Figure 5 A schematic diagram of the structure of a heat exchange pipeline in a urea reaction heat energy recovery system provided by the present invention;

[0036] Figure 6 A schematic diagram of the internal structure of a heat exchange pipe in a urea reaction heat energy recovery system provided by the present invention;

[0037] Figure 7 A schematic diagram of the structure of a scraper in a urea reaction heat recovery system provided by the present invention Figure 1 ;

[0038] Figure 8 A schematic diagram of the structure of a scraper in a urea reaction heat recovery system provided by the present invention Figure 2 ;

[0039] Fig. 9 A schematic diagram of the structure of a scraper in a urea reaction heat recovery system provided by the present invention Figure 3 ;

[0040] Fig.10 A schematic diagram of the structure of a plate frame in a urea reaction heat energy recovery system provided by the present invention;

[0041] Fig.11 A schematic structural diagram of a movable plate in a urea reaction heat energy recovery system provided by the present invention.

[0042] Description of reference numerals:

[0043] 1. Furnace body; 2. Exhaust pipe; 3. Heat recovery box; 4. Support frame; 5. Inlet main pipe; 6. Outlet main pipe; 7. Outlet pipe; 8. Inlet pipe; 9. High-temperature water tank; 10. Low-temperature water tank; 11. Connector 1; 12. Exhaust pipe; 13. Heat exchange pipe; 131. Horizontal pipe section; 132. Vertical pipe section; 133. Connecting vertical pipe; 14. Transmission screw; 15. Pull rod; 16. Scraper 2; 17. Plate frame; 171. Mounting groove; 172. Perforation; 173. Movable hole; 18. Movable plate; 19. Support rod; 191. Sliding slope; 20. Stop plate; 21. Drive block; 22. Connector 2. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0045] The following is one embodiment of a urea reaction heat recovery system provided by the present invention:

[0046] like Figure 1-Figure 11 As shown, a urea reaction heat energy recovery system includes a furnace body 1, an air outlet pipe 2, a heat recovery box 3, an exhaust pipe 12, a heat exchange component, a scraper 1, a drive block 21, a pull rod 15, a scraper 2 16, a transmission screw 14, a connector 11, a connector 22, an inlet manifold 5, an outlet manifold 6, a low-temperature water tank 10 and a high-temperature water tank 9.

[0047] like Figure 1 , Figure 2 As shown, the furnace body 1 is a urea pyrolysis furnace, which is used to heat urea for pyrolysis reaction to generate gases such as ammonia and carbon dioxide. A gas outlet is provided at the top of the furnace body 1.

[0048] The gas outlet pipe 2 is connected to the gas outlet at the top of the furnace body 1 and is used to guide the gas generated in the furnace body 1 to flow toward the reaction equipment of the next process.

[0049] The heat recovery box 3 is connected to the outlet end of the air outlet pipe 2 and communicates with the air outlet pipe 2 . The heat recovery box 3 is fixedly mounted on a support frame 4 .

[0050] The exhaust duct 12 is connected to the heat recovery box 3 and communicates with the inner cavity of the heat recovery box 3 . The exhaust duct 12 extends in the left-right direction and is located at a side of the heat recovery box 3 facing away from the furnace body 1 .

[0051] like Figure 2 , Figure 3 As shown, the heat exchange component is located in the heat recovery box 3, and the heat exchange component includes a plurality of heat exchange pipes 13 arranged at intervals on the left and right. Figure 4 , Figure 5As shown, the heat exchange pipe 13 includes a plurality of horizontal pipe sections 131 and a plurality of vertical pipe sections 132. The plurality of horizontal pipe sections 131 extend in the front-to-back direction and are arranged at equal intervals from top to bottom. A vertical pipe section 132 is connected between any two horizontal pipe sections 131 adjacent to each other. The vertical pipe section 132 is connected to the two horizontal pipe sections 131 on its upper and lower sides. Any two vertical pipe sections 132 adjacent to each other are distributed on the front and rear sides of the horizontal pipe section 131 between the two vertical pipe sections 132. The left pipe wall and the right pipe wall of the vertical pipe section 132 are both arc-shaped. The arc-shaped left pipe wall and the right pipe wall are symmetrical and coaxial, and the axis extends in the front-to-back direction.

[0052] One end of the uppermost horizontal pipe section 131 facing away from the adjacent vertical pipe section 132 below is the pipe inlet of the heat exchange pipe 13, and one end of the lowermost horizontal pipe section 131 facing away from the adjacent vertical pipe section 132 above is the pipe outlet of the heat exchange pipe 13. The pipe inlet and the pipe outlet of each heat exchange pipe 13 extend through the heat recovery box 3 to the outside of the heat recovery box 3, and a vertically extending connecting vertical pipe 133 is connected to the pipe outlet.

[0053] like Figure 6 As shown, there are multiple scraper blades 1, and the multiple scraper blades 1 are respectively adapted to be inserted into the inner cavity of each horizontal pipe section 131.

[0054] It is defined that the direction along the water flow in the heat exchange pipe 13 is a first moving direction, and the direction against the water flow is a second moving direction.

[0055] like Figure 7-Figure 11 As shown, the scraper 1 includes a plate frame 17 and a movable plate 18. The plate frame 17 is in a field shape. A through hole 172 is provided in the center of the plate frame 17. The hole axis of the through hole 172 extends in the front-to-back direction. A stop plate 20 is provided on the plate frame 17. The stop plate 20 is located at the rear side of the plate frame 17 in the first moving direction and blocks the through hole 172 in the front-to-back direction. Four mounting grooves 171 are evenly distributed around the plate frame 17. There are four movable plates 18, which are respectively inserted into the four mounting grooves 171 on the plate frame 17, and each movable plate 18 can slide on the plate frame 17 in a direction perpendicular to the hole axis of the through hole 172. An elastic member is connected between each movable plate 18 and the bottom surface of the corresponding mounting groove 171. The elastic member is a compression spring and can elastically expand and contract in a direction perpendicular to the hole axis of the through hole 172.

[0056] The specific sliding mode of the movable plate 18 on the plate frame 17 is as follows: the plate frame 17 is evenly distributed with four movable holes 173 extending in a direction perpendicular to the axis of the through hole 172 and communicating with the through hole 172, each movable hole 173 corresponds to each mounting groove 171, each movable hole 173 is slidably penetrated with a support rod 19, each movable plate 18 is respectively connected to one end of each support rod 19 facing away from the through hole 172, and the support rod 19 can slide back and forth in the movable hole 173, thereby driving each movable plate 18 to slide on the plate frame 17 along the direction perpendicular to the axis of the through hole 172. One end of each support rod 19 extending into the through hole 172 is provided with a push inclined surface 191, and each push inclined surface 191 on each support rod 19 approaches each other along the first moving direction.

[0057] There are multiple drive blocks 21, and each through hole 172 in the plate frame 17 is provided with a drive block 21. The drive block 21 fits with the push inclined surface 191 on each support rod 19 on the plate frame 17, and the drive block 21 is also stopped by the stop plate 20 in the front and back directions.

[0058] There are multiple tie rods 15, and each tie rod 15 extends in the front-to-back direction. Each driving block 21 is connected to a tie rod 15, and the tie rod 15 is located at the front side of the corresponding driving block 21 in the first moving direction, and the end of the tie rod 15 facing away from the corresponding driving block 21 passes through the side wall of the heat exchange pipe 13 and extends to the outside of the heat exchange pipe 13. By pulling the tie rod 15 to move along the first moving direction, the driving block 21 can be driven to move along the first moving direction, thereby pulling the scraper 1 to move along the first moving direction, and at the same time, the driving block 21 can push each support rod 19 away from the center of the plate frame 17, so that the movable plate 18 is pressed against the corresponding pipe wall in the horizontal pipe section 131. By pushing the pull rod 15 to move along the second moving direction, the driving block 21 can be driven to move along the second moving direction, thereby pushing the stop plate 20 to drive the scraper 1 to move along the second moving direction. At the same time, the driving block 21 can be disengaged from each sliding inclined surface 191, and each movable plate 18 is elastically reset and loosened from the pipe wall of the horizontal pipe section 131.

[0059] There are multiple scrapers 16, and each vertical pipe section 132 is provided with a scraper 16. The scraper 16 is rotatably mounted on the inner side of the vertical pipe section 132 along the rotation axis extending forward and backward, and the scraper 16 is provided with a spiral perforation 172 extending forward and backward. The width dimension of the scraper 16 in the forward and backward direction is matched with the width dimension of the vertical pipe section 132 in the forward and backward direction, and the length dimension of the scraper 16 is matched with the diameter dimension of the arc-shaped left and right pipe walls of the vertical pipe section 132. When the scraper 16 rotates in the vertical pipe section 132, the two front and rear opposite plate edges of the scraper 16 can contact the front pipe wall and the rear pipe wall of the vertical pipe section 132 respectively, and the other two plate edges of the scraper 16 can contact the left pipe wall and the right pipe wall of the vertical pipe section 132 respectively.

[0060] There are multiple transmission screws 14, and a transmission screw 14 is spirally installed in the spiral through hole 172 in each scraper 16. When the transmission screw 14 moves in the front-to-back direction, it can drive the scraper 16 to rotate in the vertical pipe section 132 to scrape off the scale on the inner wall of the vertical pipe section 132.

[0061] The connecting piece 11 is located at the front side of the heat recovery box 3, and the driving screw 14 passing through the scraper 2 16 in each vertical pipe section 132 located at the front side is connected to the connecting piece 11, and the pull rod 15 passing through the adjacent horizontal pipe section 131 above each vertical pipe section 132 located at the front side is also connected to the connecting piece 11. The connecting piece 11 is connected to the first horizontal driving cylinder, and the first horizontal driving cylinder can drive the connecting piece 11 to move back and forth.

[0062] The second connector 22 is located at the rear side of the heat recovery box 3, and the drive screw 14 inserted in the scraper 16 in each vertical pipe section 132 at the rear side is connected to the second connector 22, and the pull rod 15 inserted in the adjacent horizontal pipe section 131 above each vertical pipe section 132 at the rear side and the pull rod 15 inserted in the lowest horizontal pipe section 131 are also connected to the second connector 22. The second connector 22 is connected to the second horizontal driving cylinder, and the second horizontal driving cylinder can drive the second connector 22 to move back and forth.

[0063] The inlet main pipe 5 is connected to the outer box wall of the heat recovery box 3 , one end of the inlet main pipe 5 is closed and the other end is open, the pipe inlet of each heat exchange pipe 13 is connected to the inlet main pipe 5 , and each heat exchange pipe 13 is connected to the inner cavity of the inlet main pipe 5 .

[0064] The outlet main pipe 6 is connected to the support frame 4, one end of the outlet main pipe 6 is closed and the other end is open, the connecting vertical pipes 133 at the pipe outlets of each heat exchange pipe 13 are connected to the outlet main pipe 6, and the heat exchange pipe 13 is connected to the inner cavity of the outlet main pipe 6. A filter element is arranged in the outlet main pipe 6, and the filter element is used to filter scale floating in the water.

[0065] The low temperature water tank 10 and the high temperature water tank 9 are both mounted on the support frame 4 and are both located below the heat recovery tank 3. The open end of the inlet manifold 5 is connected to the low temperature water tank 10 through the inlet pipe 8, and the open end of the outlet manifold 6 is connected to the high temperature water tank 9 through the outlet pipe 7. A pump body is provided in the pipeline path of the inlet pipe 8, and the pump body is used to pump the water in the low temperature water tank 10 into the heat exchange pipe 13, and force the water in the heat exchange pipe 13 to flow through the outlet manifold 6 and the outlet pipe 7 and then flow into the high temperature water tank 9.

[0066] When the scraper 1 moves to the top of the vertical pipe section 132, it may interfere with the scraper 2 16. In order to avoid this situation, the thread on the transmission screw 14 is designed so that when the scraper 1 moves in the space above the vertical pipe section 132, the scraper 2 16 slides on the left and right walls of the vertical pipe section 132.

[0067] When the present invention is in use, urea is placed in the furnace body 1 for pyrolysis reaction. The high-temperature gas generated after the urea is pyrolyzed enters the heat recovery box 3 through the gas outlet pipe 2. The high-temperature gas exchanges heat with the water in the heat exchange pipe 13 in the heat recovery box 3, so that the water in the heat exchange pipe 13 is heated. The heated water flows into the high-temperature water tank 9. The hot water in the high-temperature water tank 9 can be used in other processes that require a high-temperature water source, or according to actual needs, the wet urea can be dried and preheated through the heat radiation of the high-temperature water tank 9, thereby realizing the recovery and utilization of the waste heat of the gas.

[0068] After the heat exchange pipe 13 has been working for a long time, scale will be generated on the inner wall. The scale will increase the wall thickness of the heat exchange pipe 13, resulting in a decrease in heat exchange efficiency. Therefore, the scale on the inner wall of the heat exchange pipe 13 can be scraped off regularly. During the scraping process, by driving the connector 1 11 and the connector 2 22 to move back and forth continuously, the connector 1 11 and the connector 2 22 drive the pull rod 15 and the transmission screw 14 to move back and forth continuously, thereby driving the scraper 1 to move back and forth continuously, and driving the scraper 2 16 to rotate. When the scraper 1 moves along the first moving direction, the movable plate 18 is pressed against the pipe wall of the horizontal pipe section 131, and the scale on the horizontal pipe section 131 can be scraped off. When the scraper 1 moves along the second moving direction, the movable plate 18 is loosened from the pipe wall of the horizontal pipe section 131, and has no scraping effect on the scale. The scale and the pipe wall of the horizontal pipe section 131 have no obstruction effect on the movable plate 18, and the movement of the scraper 1 along the second moving direction is easier. The direction of the scraper 1 scraping scale is the same as the direction of the water flow, and the scale is easier to fall off the pipe wall. When the scraper 2 16 rotates, the scale on the four pipe walls of the vertical pipe section 132 can be scraped off, and the scraped scale is finally discharged from the pipe outlet of the heat exchange pipe 13 to the outlet main pipe 6 along with the water flow. The scale is filtered by the filter element in the outlet main pipe 6 and remains in the outlet main pipe 6, preventing the scale from being brought into the high-temperature water tank 9.

[0069] The present invention can effectively remove scale on each inner wall of the spiral heat exchange pipe 13, and can remove scale on the inner wall of the pipe during the operation of the heat exchange pipe 13, with good removal effect, and does not affect the normal operation of the heat exchange pipe 13.

[0070] In this embodiment, a pull rod 15 is provided on the scraper 1, and the pull rod 15 is pulled to drive the scraper 1 to slide back and forth in the horizontal pipe section 131 to scrape off the scale in the horizontal pipe section 131. In other embodiments, a screw rod extending forward and backward is rotatably installed in the horizontal pipe section 131, and the scraper 1 is spirally mounted on the screw rod. By driving the screw rod to rotate, the scraper 1 is driven to move back and forth in the horizontal pipe section 131.

[0071] In this embodiment, scraper 1 includes a plate frame 17 and a movable plate 18, and the movable plate 18 is elastically slidably mounted on the plate frame 17 in a direction perpendicular to the axis of the through hole 172. In other embodiments, scraper 1 only includes a flat plate, and the side walls of the flat plate are tightly attached to the walls of the horizontal pipe section 131. The pull rod 15 is vertically connected to the center of the flat plate, and the flat plate is provided with through holes running through the front and back for water to flow through.

[0072] In this embodiment, scraper blade 2 16 cooperates with the drive screw 14 in a spiral transmission, and the scraper blade 2 16 is driven to rotate by pulling the drive screw 14 forward and backward. In other embodiments, the scraper blade 2 16 is connected to a rotating shaft extending forward and backward, and the drive motor is connected to the rotating shaft to drive the scraper blade 2 16 to rotate in the vertical pipe section 132.

Claims

1. A urea reaction heat recovery system, comprising a furnace body, characterized in that: The furnace body is connected to an exhaust pipe, the end of the exhaust pipe is connected to a heat recovery box, the heat recovery box is connected to an exhaust pipe, and a heat exchange component is arranged in the heat recovery box, and the heat exchange component includes a plurality of heat exchange pipes arranged at intervals on the left and right; The heat exchange pipe comprises a plurality of horizontal pipe sections which are arranged at intervals in the upper and lower parts and extend in the front-to-back direction. A vertical pipe section for connecting the two horizontal pipe sections is connected between the ends of any two vertically adjacent horizontal pipe sections. Any two vertically adjacent vertical pipe sections are arranged at the front and rear ends of the horizontal pipe section between the two vertical pipe sections. The top opening of the heat exchange pipe is the pipe inlet, and the bottom opening is the pipe outlet. Each horizontal pipe section is adapted to be inserted with a scraper 1, which can slide back and forth in the horizontal pipe section to scrape off the scale on the inner wall of the horizontal pipe section; The left and right pipe walls of the vertical pipe section are both arc-shaped and coaxial, and their axes extend in the front-to-back direction. A scraper 2 is provided in each vertical pipe section. The width dimension of the scraper 2 in the front-to-back direction is matched with the inner diameter dimension of the vertical pipe section in the front-to-back direction. The scraper 2 is installed in the vertical pipe section and rotates around the axis of the arc-shaped side wall. During the rotation of the scraper 2, the scale on the inner walls of the vertical pipe section can be scraped off.

2. A urea reaction heat recovery system according to claim 1, characterized in that: A pull rod extending forward and backward is provided on the scraper one, and the end of the pull rod facing away from the scraper one is passed through the outside of the heat exchange pipe. When the pull rod is pulled forward and backward, it can drive the scraper one to slide forward and backward in the horizontal pipe section to scrape off scale.

3. A urea reaction heat recovery system according to claim 2, characterized in that: A transmission screw extending forward and backward is spirally installed in the scraper plate 2. When the transmission screw is pulled forward and backward, it can drive the scraper plate 2 to rotate in the vertical pipe section to scrape off the scale.

4. A urea reaction heat recovery system according to claim 3, characterized in that: Connector 1 and connector 2 are respectively provided on the front and rear sides of the heat recovery box. The transmission screws inserted in the scraper 2 in each vertical pipe section on the front side are all connected to connector 1, and the pull rods inserted in each adjacent horizontal pipe section above the vertical pipe section on the front side are also connected to connector 1. The remaining pull rods and transmission screws are all connected to connector 2. Connector 1 and connector 2 can move back and forth in the front and rear directions to drive scraper 1 to slide back and forth and drive scraper 2 to rotate to scrape off the scale in the heat exchange pipe.

5. A urea reaction heat recovery system according to any one of claims 2-4, characterized in that: The scraper 1 includes a plate frame and a plurality of movable plates, the plurality of movable plates are evenly distributed on the plate frame around a central axis extending forward and backward, and each movable plate is movably mounted on the plate frame. The direction along the water flow in the heat exchange pipe is defined as a first moving direction, and the direction against the water flow is defined as a second moving direction. When the scraper 1 moves along the first moving direction, each movable plate can move away from the center of the plate frame and be pressed against each pipe wall of the horizontal pipe section respectively. When the scraper 1 moves along the second moving direction, each movable plate can gather toward the center of the plate frame to be loosened from the pipe wall of the corresponding horizontal pipe section.

6. A urea reaction heat recovery system according to claim 5, characterized in that: A through hole running through the front and back is provided in the middle of the plate frame, and each movable plate is connected with a support rod, which is elastically slidably installed on the plate frame along a direction perpendicular to the axis of the through hole, and one end of each support rod facing away from the movable plate extends into the through hole, and an end of the support rod extending into the through hole is provided with a sliding slope, and each sliding slope approaches each other along a first moving direction. A driving block is provided in the through hole, and the driving block is located in the area surrounded by each sliding slope. When the driving block moves along the first moving direction, it can push each support rod away from the center of the plate frame through the sliding slope, so as to drive the movable plate away from the center of the plate frame and press it against the corresponding pipe wall in the horizontal pipe section, and the pull rod is connected to the driving block.

7. A urea reaction heat recovery system according to claim 6, characterized in that: A stop plate is also provided on the plate frame, which is located in front of the driving block in the second moving direction. The stop plate and the driving block stop each other front and back. When the driving block moves along the second moving direction, it can push the stop plate and drive the scraper to move along the second moving direction.

8. A urea reaction heat recovery system according to any one of claims 1 to 4, characterized in that: The top inlet of each heat exchange pipe is connected to an inlet main pipe extending left and right, and the bottom outlet of each heat exchange pipe is connected to an outlet main pipe extending left and right. A low-temperature water tank and a high-temperature water tank are arranged below the heat recovery tank. One end of the inlet main pipe is closed, and the other end is connected to the low-temperature water tank. One end of the outlet main pipe is closed, and the other end is connected to the high-temperature water tank. A filter element is arranged in the outlet main pipe, and a pump body is arranged between the inlet main pipe and the water tank. The pump body is used to pump the water in the low-temperature water tank into each heat exchange pipe, and force the heated hot water in the heat exchange pipe to flow into the high-temperature water tank.

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