A dryer hydrophobic waste heat recycling system

Abstract

The utility model relates to mixing equipment technical field, the utility model discloses a dryer drainage waste heat recycling system, including drain pipe, expansion vessel, first water tank, stirring tank, first pumping assembly, ration unloading mechanism, second water tank and second pumping assembly, and drain pipe is introduced high temperature drainage, expansion vessel entrance is linked with drain pipe, first water tank and second water tank all are located in the below of expansion vessel, and with expansion vessel intercommunication, and second water tank is connected with second inlet pipe, the stirring tank includes jar, first inlet pipe and stirring mechanism, first inlet pipe imports normal temperature desalted water to jar, and pumping assembly is connected between jar and corresponding water tank, and ration unloading mechanism is located in the top of jar, and the bottom of jar is equipped with liquid discharge pipe, the dryer drainage waste heat recycling system provided by the utility model, through directly mixing high temperature drainage and normal temperature desalted water, quickly mixes to the best temperature of urea solution, realizes the efficient recovery and utilization of high temperature drainage waste heat.

Description

Technical Field

[0001] This utility model relates to the field of mixing equipment technology, and in particular to a system for recovering and utilizing the hydrophobic waste heat of a dryer. Background Technology

[0002] In boiler flue gas denitrification systems, urea solution is typically prepared as a reducing agent. Currently, urea solution is mostly prepared using electrically heated stirred tanks. These tanks generally include a tank body, an electric heating device located within the tank, and a stirring mechanism. During production, room-temperature demineralized water is first added to the tank. Then, the electric heating device is activated to raise the water temperature to a preset temperature (usually 50℃-60℃). Solid urea is then added and stirred to dissolve, ultimately obtaining a urea solution of the appropriate concentration. This solution is then pumped to the injection point for denitrification. However, in actual operation, it has been found that the electric heating method has high energy consumption, especially in large-scale production scenarios such as waste treatment, leading to increased operating costs.

[0003] Meanwhile, in sludge drying projects, it is typically necessary to dry wet sludge with a moisture content of approximately 80% to a low moisture content of 35% ± 5%. To achieve this stringent drying requirement, most dryers employ indirect steam heating drying technology. In this technology, the dryer includes a heating chamber for containing the sludge and an indirect steam heating device located outside the heating chamber. During operation, saturated steam is introduced into the heating device, and the latent heat released by the steam heats the heating chamber through heat conduction, thereby indirectly heating the sludge inside. The sludge evaporates its moisture upon heating, achieving drying; while the steam, after releasing its latent heat in the indirect heating device, condenses into high-temperature condensate that can still maintain a temperature of around 110°C. Currently, this high-temperature condensate is generally cooled by circulating water and then recycled to the steam condensate tank. This cooling process results in a large amount of high-quality waste heat contained in the condensate being directly discharged into the environment, failing to be effectively utilized and causing serious energy waste.

[0004] Currently, existing technologies have not yet achieved an effective coupling and utilization of the heat energy consumption required for urea solution preparation and the high-temperature hydrophobic waste heat emitted by the dryer. There is a lack of an integrated system that can recover the high-temperature hydrophobic waste heat generated by the dryer and use it for urea solution preparation.

[0005] It is evident that existing technologies still need improvement and enhancement. Utility Model Content

[0006] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a dryer hydrophobic waste heat recovery and utilization system to solve the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A system for recovering and utilizing the hydrophobic waste heat of a dryer, comprising: A condensate drain pipe is used to connect the condensate outlet of the steam indirect heating device of the dryer; An expansion container, whose inlet is connected to a condensate drain pipe, is used for vapor-liquid separation of high-temperature condensate from the dryer; The first water tank is located below the expansion container, and the bottom of the expansion container is connected to the top of the first water tank through the first drain pipe; A mixing tank includes: a tank body, a first water inlet pipe connected to the tank body, and a liquid level sensor, a temperature sensor, and a stirring mechanism disposed in the tank body; the first water inlet pipe is used to input room temperature demineralized water into the tank body; The first pumping assembly is connected between the tank body and the first water tank, and is used to pump the high-temperature condensate in the first water tank into the tank body; A quantitative feeding mechanism, located above the tank, is used to quantitatively add urea into the tank. The second water tank is connected to the bottom of the expansion container via a second drain pipe at its top; a second water inlet pipe is connected to the second water tank and is used to input room temperature demineralized water into the second water tank. The second pumping assembly is connected between the second water tank and the tank body, and is used to pump the medium-temperature condensate in the second water tank into the tank body; the high-temperature condensate in the first water tank is higher than the medium-temperature condensate in the second water tank. The tank has a drain pipe at the bottom for discharging the urea solution inside.

[0008] Furthermore, the quantitative feeding mechanism includes a hopper, a feeding channel located at the bottom of the hopper, and a roller rotatably located within the feeding channel; the outer circumference of the roller is provided with a plurality of grooves distributed circumferentially around its axis; the end of the feeding channel is connected to a feed pipe communicating with the tank body; wherein, when the roller rotates, its grooves can receive and quantitatively discharge urea.

[0009] Furthermore, the mixing tank is configured as two, and a three-way pipe is connected to the lower end of the material discharge channel. The two outlets of the three-way pipe are respectively connected to the feed pipes of the two mixing tanks. A swingable baffle is provided inside the three-way pipe to selectively guide the urea flow to one of the mixing tanks.

[0010] Furthermore, the mixing tank also includes a sealing mechanism, wherein the feed pipe extends downward into the interior of the tank, and the sealing mechanism includes: The sealing plate is conical in shape and located below the feed pipe; The first lifting assembly is located on the tank body and drives the sealing plate to move vertically up and down to close or open the lower port of the feed pipe.

[0011] Furthermore, the mixing tank also includes a cleaning mechanism, which includes: A ring-shaped water supply pipe is installed inside the tank in a height-adjustable manner. The ring-shaped water supply pipe is equipped with several first nozzles facing the inner wall of the tank and several second nozzles facing the bottom of the tank. The second lifting assembly is located on the tank body and is used to drive the annular water pipe to move up and down in the vertical direction; The third inlet pipe connects the second pumping assembly and the annular water supply pipe, and is used to pump the medium-temperature condensate pump in the second water tank to the annular water supply pipe. The drain pipe has a filter screen at one end inside the tank; the bottom of the tank is connected to a waste pipe to discharge the wastewater and insoluble impurities after cleaning.

[0012] Furthermore, the bottom of the tank is provided with a liquid collecting hopper in the shape of a funnel; The waste discharge pipe is connected to the bottom of the liquid collection hopper; The drain pipe is connected to the inclined side wall of the collection hopper, and the height of the connection opening is higher than the bottom of the collection hopper.

[0013] Furthermore, it also includes a filtration mechanism, which includes: The filter box has its inlet end connected to the waste discharge pipe, and at least one filter component is installed inside the filter box. The third pumping assembly, connected to the first inlet pipe and the outlet of the filter box, is used to transport the wastewater treated by the filtration assembly back to the tank.

[0014] Furthermore, the drain pipe is provided with a backflush pipe, the inlet end of which is connected to the second pumping assembly, and the outlet end of which is provided with a third nozzle facing the filter screen. The lower end of the drain pipe is connected to a first branch pipe that communicates with the waste discharge pipe. The first branch pipe is equipped with a first valve to control its opening and closing. The side wall of the drain pipe is connected to a second branch pipe for discharging urea solution. The second branch pipe is equipped with a second valve to control its opening and closing.

[0015] Beneficial effects: This invention provides a system for recovering and utilizing waste heat from a dryer's hydrophobic residue. By setting up a first and second water tank, a two-stage heat source system is constructed, providing both high and medium temperatures. The system can directly store the high-temperature hydrophobic residue from the dryer as a high-temperature heat source, or pre-mix it with ambient-temperature demineralized water in the second water tank to prepare a stable medium-temperature heat source, depending on process requirements. During urea solution preparation, by flexibly controlling the first and second pumping components, hydrophobic residues at different temperatures can be pumped individually or proportionally into the mixing tank, where they are rapidly mixed with the added ambient-temperature demineralized water to the optimal temperature required for urea dissolution. Subsequently, the stirring mechanism thoroughly and uniformly mixes and dissolves the quantitatively added urea raw material with the pre-set temperature mixture, forming a stable urea solution. The entire system utilizes the high-temperature hydrophobic residue generated during sludge drying for urea solution preparation, achieving efficient recovery and utilization of waste heat. While ensuring solution quality, it improves the system's economy and energy efficiency. The two-stage heat source system significantly enhances the ability to control the temperature of the mixed solution and improves response speed. Attached Figure Description

[0016] Figure 1 Connection principle diagram of the dryer hydrophobic waste heat recovery and utilization system provided by this utility model; Figure 2 A cross-sectional view of the mixing tank in the dryer hydrophobic waste heat recovery system provided by this utility model; Figure 3 Structural diagram of the mixing tank in the dryer hydrophobic waste heat recovery system provided by this utility model; Figure 4 Structural diagram of the cleaning mechanism in the dryer hydrophobic waste heat recovery and utilization system provided by this utility model; Figure 5 A cross-sectional view of the tank in the dryer waste heat recovery system provided by this utility model; Figure 6 A structural diagram of the quantitative feeding mechanism in the dryer hydrophobic waste heat recovery and utilization system provided by this utility model; Figure 7 A cross-sectional view of the material discharge channel in the dryer waste heat recovery system provided by this utility model; Figure 8 Structural diagram of the baffle in the dryer hydrophobic waste heat recovery and utilization system provided by this utility model; Figure 9 A cross-sectional view of the filtration mechanism in the dryer hydrophobic waste heat recovery system provided by this utility model.

[0017] Reference numerals: 1. Drainage pipe; 11. Dryer; 2. Expansion container; 21. First drain pipe; 22. Second drain pipe; 3. First water tank; 31. First pumping assembly; 4. Mixing tank; 41. Tank body; 411. Collection hopper; 412. Rib; 42. First inlet pipe; 43. Liquid level sensor; 44. Temperature sensor; 45. Mixing mechanism; 451. Mixing motor; 452. Mixing shaft; 453. Mixing paddle; 46. Drainage pipe; 461. Filter screen; 462. Backflush pipe; 463. Third nozzle; 464. First branch pipe; 465. Second branch pipe; 466. Second valve; 467. Sealing mechanism; 47. Sealing plate; 471. First lifting assembly; 472. Cleaning mechanism; 48. Annular water supply pipe; 481. Slide seat; 4811. First nozzle; 482. Second nozzle 483, second lifting assembly 484, frame 4841, lifting hydraulic cylinder 4842, movable plate 4843, first guide rod 4844, second guide rod 4845, third guide rod 4846, third water inlet pipe 485, waste discharge pipe 49, quantitative feeding mechanism 5, hopper 51, material drop channel 52, roller 53, groove 531, feeding motor 54, vibrating motor 55, feeding pipe 6, tee pipe 61, baffle 62, rotating shaft 63, swing rod 64, strip hole 641, reversing cylinder 65, pin shaft 651, annular cone surface 66, limit block 67, second water tank 7, second water inlet pipe 71, second pumping assembly 72, filtration mechanism 8, filter box 81, filter assembly 82, third pumping assembly 83. Detailed Implementation

[0018] This utility model provides a system for recovering and utilizing the hydrophobic waste heat of a dryer. To make the purpose, technical solution, and effects of this utility model clearer and more explicit, the following describes this utility model in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0019] In the description of this utility model, it should be understood that the terms "upper," "lower," "left," and "right," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limitations on this utility model. Furthermore, "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "multiple" means two or more.

[0020] Please see Figures 1 to 9As shown, this utility model provides a dryer condensate waste heat recovery system, including a condensate pipe 1, an expansion container 2, a first water tank 3, a stirring tank 4, a first pumping assembly 31, a quantitative feeding mechanism 5, a second water tank 7, and a second pumping assembly 72. The condensate pipe 1 is used to connect to the condensate outlet of the dryer 11; the inlet of the expansion container 2 is connected to the condensate pipe 1 for vapor-liquid separation of the high-temperature condensate from the dryer 11; the first water tank 3 is located below the expansion container 2, and the bottom of the expansion container 2 is connected to the top of the first water tank 3 through a first drain pipe 21; the stirring tank 4 includes: a tank body 41, a first water inlet pipe 42 connected to the tank body 41, and a liquid level sensor 43, a temperature sensor 44, and a stirring mechanism 45 disposed inside the tank body 41; the first water inlet pipe 42 is used to input constant temperature and humidity into the tank body 41. The tank contains demineralized water; a first pumping assembly 31 is connected between the tank body 41 and the first water tank 3 to pump the high-temperature condensate in the first water tank 3 into the tank body 41; a quantitative feeding mechanism 5 is located above the tank body 41 to quantitatively add urea into the tank body 41; the top of the second water tank 7 is connected to the bottom of the expansion container 2 through a second drain pipe 22; a second water inlet pipe 71 is connected to the second water tank 7 to input room temperature demineralized water; a second pumping assembly 72 is connected between the second water tank 7 and the tank body 41 to pump the medium-temperature condensate in the second water tank 7 into the tank body 41; the high-temperature condensate in the first water tank 3 is higher than the medium-temperature condensate in the second water tank 7; and a drain pipe 46 is provided at the bottom of the tank body 41 to discharge the urea solution in the tank body 41.

[0021] During operation, high-temperature steam condensate from dryer 11 enters expansion tank 2 via drain pipe 1 for vapor-liquid separation. The separated high-temperature condensate reaches a temperature of up to 98℃ and can be routed as needed: either through first drain pipe 21, flowing by gravity into first water tank 3 below for storage, or through second drain pipe 22, entering second water tank 7. The high-temperature condensate entering second water tank 7 mixes with room-temperature demineralized water replenished by second inlet pipe 71, forming a lower-temperature intermediate-temperature condensate, whose temperature can be stably maintained at approximately 75℃±5℃. When urea solution needs to be prepared, the system can, according to process requirements, pump the high-temperature condensate from first water tank 3 via first pumping component 31 and / or the intermediate-temperature condensate from second water tank 7 via second pumping component 72 to tank 41 of mixing tank 4. Simultaneously, room-temperature demineralized water is injected into tank 41 through first inlet pipe 42. By flexibly controlling the delivery ratio of hydrophobic materials at different temperatures, the mixture can be quickly heated to the preset temperature required for urea dissolution, typically 50℃-60℃. This process is monitored in real time by a temperature sensor 44 inside the tank 41, and the liquid level in the tank 41 is monitored by a level sensor 43 to prevent overflow due to excessive liquid level. Subsequently, the metering feeding mechanism 5 above the tank 41 adds a metered amount of solid urea into the tank, and the stirring mechanism 45 is activated to fully dissolve the urea, forming a uniform urea mixture. Finally, the mixture is discharged through the drain pipe 46 at the bottom of the tank 41 for use in the boiler flue gas denitrification system.

[0022] Through the above setup, the high-temperature hydrophobic waste heat generated during sludge drying is directly recovered for the preparation of urea solution. This waste heat replaces the energy consumption that relies entirely on electric heating in traditional processes, significantly reducing operating costs. By constructing a flexible, adjustable high- and medium-temperature two-stage heat source, the system achieves graded and efficient utilization of hydrophobic waste heat and enables rapid and precise control of the mixed liquor temperature.

[0023] It should be noted that both the first drain pipe 21 and the second drain pipe 22 are equipped with electromagnetic switch valves to control the on / off state of their respective pipelines, thereby selectively introducing the high-temperature condensate separated in the expansion container 2 into the first water tank 3 or the second water tank 7 according to actual needs. Simultaneously, both the first water tank 3 and the second water tank 7 are equipped with level sensors and temperature sensors to monitor the liquid level and water temperature in each tank in real time, thereby achieving stable control of the heat source supply. Furthermore, the outer walls of both the first water tank 3 and the second water tank 7 are covered with an insulation layer to effectively reduce heat loss of the high-temperature condensate during storage and improve system energy efficiency.

[0024] In this embodiment, the high-temperature steam used in the indirect steam heating device of the dryer 11 originates from an industrial boiler. Because industrial boilers have strict requirements for feedwater quality, demineralized water must be used. Demineralized water is industrial water with salts and impurities removed, preventing boiler scaling and corrosion and ensuring steam quality. Therefore, after this high-quality steam is used in the indirect steam heating device of the dryer 11 to indirectly release latent heat, the high-temperature condensate produced is still clean demineralized water, which can be directly mixed with the ambient temperature demineralized water replenished to the system for preparing urea solution without additional treatment.

[0025] The expansion container 2 used in this embodiment is a hydrophobic expansion container, a conventional existing device. Its function is to expand and depressurize the condensate in the pressure condensate pipe 1 and to separate the vapor and liquid. In this embodiment, the separated high-temperature condensate is discharged from the bottom of the expansion container 2 and flows into the first water tank 3 by gravity, without the need for additional power supply. Through the above settings, not only is the continuity and stability of condensate delivery ensured, but the energy consumption of the system operation is also further reduced.

[0026] It should be noted that the temperature of the mixed solution is mainly controlled by adjusting the mixing ratio of high-temperature hydrophobic water to room-temperature demineralized water. This is a mature temperature control method in the field and is easy to implement. Specifically, the first inlet pipe 42 is connected to a demineralized water supply pipeline, and the injection flow rate of the room-temperature demineralized water is controlled by a regulating valve installed on it. The system operates based on the volumetric control principle: firstly, through experiments or calculations, the theoretical volume ratio of high-temperature hydrophobic water to room-temperature demineralized water is determined when preparing the required volume of mixed solution at the target temperature. In actual operation, the temperature sensor 44 monitors the temperature of the mixed solution in the tank in real time; simultaneously, the liquid level sensor 43 monitors the liquid level in the tank in real time, thereby calculating the total volume of the injected liquid. Based on the above theoretical ratio, the deviation between the real-time temperature and the target temperature, and the current liquid volume, the system dynamically adjusts the actions of the regulating valve on the first pumping component 31 and the first inlet pipe 42, thereby controlling the final injection volume of the two liquids. This volume ratio adjustment method combining temperature and liquid level feedback is a conventional automatic control technology that can reliably and accurately stabilize the temperature of the mixed solution within the preset range.

[0027] In the above, the liquid level sensor 43 is preferably a hydrostatic liquid level transmitter, which is easy to install and maintain, and provides stable and reliable measurement; the temperature sensor 44 can be a contact temperature sensor, and to improve the representativeness and accuracy of the detection, multiple temperature measuring points can be arranged at different heights inside the box.

[0028] In a preferred embodiment, see [reference] Figure 6 , 7The quantitative feeding mechanism 5 includes a hopper 51, a feeding channel 52 located at the bottom of the hopper 51, and a roller 53 rotatably located in the feeding channel 52. The outer periphery of the roller 53 is provided with a plurality of grooves 531 distributed around its axis. The end of the feeding channel 52 is connected to a feed pipe 6 communicating with the tank body 41. When the roller 53 rotates, its grooves 531 can receive and quantitatively discharge urea. Specifically, the projection area of ​​the groove 531 on the horizontal plane corresponds to the cross-sectional shape and size of the material discharge channel 52, so as to ensure that the groove 531 can completely receive the falling urea when it rotates to the bottom of the hopper 51, and can close the material discharge channel 52 when it rotates to face the feed pipe 6, ensuring that only the urea in the groove 531 falls into the feed pipe 6. In addition, after the material is discharged, the corresponding empty groove 531 can block the material discharge channel 52 to prevent the mist in the tank 41 from entering the hopper 51 through the material discharge channel 52, thus playing a sealing and moisture-proof role. The quantitative feeding mechanism 5 also includes a feeding motor 54 fixed to the outer wall of the feeding channel 52. The output shaft of the feeding motor 54 is coaxially connected to the roller 53 to drive the roller 53 to rotate. During feeding, the roller 53 rotates stepwise under the drive of the feeding motor 54. When a certain groove 531 rotates to the bottom of the hopper 51, the groove 531 is filled with urea. As the roller 53 continues to rotate, the groove 531 carries a fixed amount of urea to the position above the feed pipe 6. At this time, the urea in the groove 531 falls into the feed pipe 6 under the action of gravity, and then enters the tank 41. By controlling the rotation angle or speed of the roller 53, the amount of urea falling into the tank 41 per unit time can be controlled, thereby realizing continuous and quantitative urea addition.

[0029] Preferably, see Figure 6 The outer wall of the silo 51 is equipped with a vibration motor 55. The high-frequency, low-amplitude mechanical vibration generated by the vibration motor 55 during operation is transmitted to the wall of the silo 51 to eliminate the bridging phenomenon of urea in the silo 51 and ensure continuous and stable material feeding.

[0030] In a preferred embodiment, see [reference] Figure 1 , 3 The mixing tank 4 is configured as two units. A three-way pipe 61 is connected to the lower end of the material discharge channel 52. The two outlets of the three-way pipe 61 are respectively connected to the feed pipes 6 of the two mixing tanks 4. A swingable baffle 62 is installed inside the three-way pipe 61 to selectively guide urea flow to one of the mixing tanks 4. The two mixing tanks 4 can share a single quantitative feeding mechanism 5, enabling alternating operation and continuous production. By controlling the swing direction of the baffle 62 inside the three-way pipe 61, urea can be selectively introduced into the feed pipe 6 of one mixing tank 4, while the other mixing tank 4 can simultaneously perform mixing, drainage, or cleaning processes. This alternating operation ensures seamless connection between the urea dissolution and preparation process and the discharge process, achieving a continuous and stable supply of urea solution.

[0031] Further, see Figure 6 , 7 8. The three-way pipe 61 has an inverted Y-shaped structure. A horizontally positioned rotating shaft 63 is fixed on the baffle 62. The rotating shaft 63 is rotatably connected to the three-way pipe 61, and its end extends outside the three-way pipe 61 and is connected to a rocker arm 64. The rocker arm 64 has a strip-shaped hole 641 extending along its length. A reversing cylinder 65 is connected to the outside of the three-way pipe 61. The piston rod end of the reversing cylinder 65 is provided with a pin 651, which is slidably embedded in the strip-shaped hole 641. When the reversing cylinder 65 extends or retracts, its piston rod slides in the strip-shaped hole 641 through the pin 651 and drives the rocker arm 64 to swing around the rotating shaft 63, thereby driving the baffle 62 to deflect within the three-way pipe 61, realizing precise switching of the urea flow direction.

[0032] Preferably, see Figure 7 A limiting block 67 is fixed at the bifurcation of the three-way pipe 61 where it connects to the two feed pipes 6. This limiting block 67 is used to limit the maximum deflection angle of the baffle 62, preventing it from swinging excessively and causing seal failure or jamming. The setting of the limiting block 67 will not affect or block the normal flow path of urea.

[0033] In a preferred embodiment, see [reference] Figure 6 The mixing tank 4 also includes a sealing mechanism 47. The feed pipe 6 extends downward into the tank body 41. The sealing mechanism 47 includes a sealing plate 471 and a first lifting assembly 472. The sealing plate 471 has a conical structure and is located below the feed pipe 6. The first lifting assembly 472 is mounted on the tank body 41 and drives the sealing plate 471 to move vertically up and down to close or open the lower port of the feed pipe 6. After urea addition is completed, the first lifting assembly 472 drives the sealing plate 471 to rise, so that its conical surface tightly fits the lower port of the feed pipe 6, thereby achieving a reliable seal. By setting the sealing plate 471, it is possible to effectively prevent the mist generated inside the tank due to the high temperature from entering the feed pipe 6 during the non-feeding stage, thereby avoiding the problem of caking caused by the damp inner wall of the feed pipe 6 and the urea particles sticking to the pipe wall due to moisture, ensuring the smoothness and quantitative accuracy of the subsequent feeding process.

[0034] In the above, the first lifting component 472 may be a mechanism such as a cylinder, electric push rod, or hydraulic cylinder that can drive the sealing plate 471 to rise and fall in the vertical direction.

[0035] The aforementioned sealing plate 471 adopts a conical structure. When urea particles fall through the feed pipe 6, some particles will naturally slide along the inclined surface of the cone, while others will bounce outwards after colliding with the cone surface. The conical surface breaks the concentrated falling trajectory of the urea, allowing it to achieve a certain degree of lateral dispersion in the initial stage of falling. This effectively avoids local accumulation or clumping of urea in the tank 41, thereby improving the initial uniformity of urea distribution in the solution and facilitating the mixing of urea and demineralized water.

[0036] Preferably, see Figure 6 The lower end of the feed pipe 6 is provided with an annular conical surface 66, which matches the conical shape of the sealing plate 471. When the first lifting assembly 472 drives the sealing plate 471 to rise or fall, the sealing plate 471 fits against the annular conical surface 66 to achieve a seal.

[0037] Preferably, on a horizontal plane, the projected area of ​​the sealing plate 471 is larger than the projected area of ​​the annular conical surface 66 of the feed pipe 6. After the sealing plate 471 descends during the feeding stage, its plate body can still shield the area directly below the lower end of the feed pipe 6, effectively blocking the rising mist inside the tank and preventing it from entering the inner wall of the feed pipe 6, thereby reducing the risk of urea becoming damp and sticking.

[0038] In a preferred embodiment, see [reference] Figure 2 , 4 The mixing tank 4 also includes a cleaning mechanism 48, which includes an annular water supply pipe 481, a second lifting assembly 484, and a third water inlet pipe 485. The annular water supply pipe 481 is vertically and vertically disposed inside the tank body 41. The annular water supply pipe 481 is provided with a plurality of first nozzles 482 facing the inner wall of the tank body 41 and a plurality of second nozzles 483 facing the bottom of the tank body 41. Specifically, the first nozzles 482 and the second nozzles 483 are arranged in a uniform array along the circumference of the annular water supply pipe 481, and the spray range of adjacent first nozzles 482 overlaps with each other in the circumference of the tank wall to ensure full circumferential coverage of the inner wall without dead corners. The spray range of adjacent second nozzles 483 effectively overlaps in the bottom area of ​​the tank body 41 to ensure uniform rinsing of the entire bottom of the tank body 41.

[0039] The second lifting assembly 484 is mounted on the tank 41 and is used to drive the annular water supply pipe 481 to move vertically up and down. The third inlet pipe 485 connects the second pumping assembly 72 and the annular water supply pipe 481 and is used to pump the medium-temperature condensate in the second water tank 7 to the annular water supply pipe 481. A filter screen 461 is installed at one end of the drain pipe 46 inside the tank 41. A waste discharge pipe 49 is connected to the bottom of the tank 41 to discharge the wastewater and insoluble impurities after cleaning. When the mixing tank 4 completes the discharge of a batch of urea solution and needs cleaning, the second pumping assembly 72 pumps the medium-temperature condensate in the second water tank 7 into the annular water supply pipe 481 through the third inlet pipe 485. Simultaneously, the second lifting assembly 484 drives the annular water supply pipe 481 to perform a slow reciprocating lifting motion inside the tank, specifically two or three lifting cycles. High-pressure water is sprayed from multiple first nozzles 482 and second nozzles 483 to achieve automatic cleaning of the tank 41. The medium-temperature demineralized water itself has excellent dissolving and rinsing capabilities, effectively dissolving and removing residual urea crystals and other insoluble impurities. The rinsed wastewater collects at the bottom of the tank and is discharged through the waste pipe 49. In addition, using the existing medium-temperature demineralized water in the system as a cleaning medium, the tank 41 can be preheated while completing the rinsing process, preparing for the next round of production.

[0040] See above. Figure 2 , 4 The second lifting assembly 484 includes a frame 4841, a lifting hydraulic cylinder 4842 mounted on the frame 4841, and a movable plate 4843 located at the end of the piston rod of the lifting hydraulic cylinder 4842. The tank body 41 is mounted on the frame 4841 and located below the lifting hydraulic cylinder 4842. Several first guide rods 4844 are vertically mounted on the frame 4841, and the movable plate 4843 is slidably engaged with the first guide rods 4844. Several second guide rods 4845 are provided at the bottom of the movable plate 4843. The second guide rods 4845 extend downward and are connected to the annular water supply pipe 481. The second guide rods 4845 and the top of the tank body 41 are dynamically sealed to allow vertical sliding while keeping the tank body 41 sealed. When the piston rod of the lifting hydraulic cylinder 4842 extends or retracts, it drives the movable plate 4843 to smoothly rise and fall along the first guide rod 4844. This, in turn, drives the annular water pipe 481 to move synchronously up and down within the tank 41 via the second guide rod 4845, adjusting its cleaning position. Both the first guide rod 4844 and the second guide rod 4845 serve a guiding function, effectively preventing the annular water pipe 481 from tilting or rotating during the lifting process. Optionally, one of the second guide rods 4845 is connected to the annular water pipe 481 and can be used as a third water inlet pipe 485.

[0041] Preferably, see Figure 4Several third guide rods 4846 are vertically arranged inside the tank body 41, and several sliding seats 4811 are provided on the annular water conveying pipe 481. Each sliding seat 4811 is slidably sleeved on the corresponding third guide rod 4846. The addition of sliding cooperation between the sliding seat 4811 and the third guide rod 4846 further improves the lifting stability of the annular water conveying pipe 481 and effectively suppresses its shaking under the impact of high-speed water flow.

[0042] Preferably, see Figure 5 The inner wall of the tank 41 is vertically provided with several ribs 412. The ribs 412 can effectively break the regular flow field formed during the stirring process, increase fluid disturbance, and eliminate vortices, thereby improving the mixing efficiency and uniformity of urea and demineralized water. The third guide rod 4846 is located on the side of the ribs 412 facing away from the rotation direction of the stirring paddle 453. It can form a hydrodynamic shield for the third guide rod 4846, avoiding it from being directly subjected to the frontal impact of the mainstream generated by stirring, thereby reducing vibration and wear.

[0043] See above. Figure 5 The stirring mechanism 45 includes a stirring motor 451, a stirring shaft 452 connected to the output shaft of the stirring motor 451, and a plurality of stirring paddles 453 disposed on the stirring shaft 452. The stirring motor 451 drives the stirring shaft 452 to rotate, thereby causing the stirring paddles 453 to generate shearing and pushing action in the demineralized water in the tank 41, forming turbulent flow and circulation, so that urea and demineralized water can be quickly and fully mixed and dissolved.

[0044] In practical applications, a small amount of insoluble impurities may remain in the urea solution after mixing and dissolving. When discharging the urea mixture, the filter screen 461 installed at the inlet of the drain pipe 46 can effectively intercept these impurities, allowing the clean urea solution to be output through the drain pipe 46, thereby preventing impurities from entering the subsequent conveying pipeline and the denitrification injection system.

[0045] In a preferred embodiment, see [reference] Figure 5 The tank 41 has a funnel-shaped liquid collection hopper 411 at its bottom; the waste discharge pipe 49 is connected to the bottom of the liquid collection hopper 411, which can completely empty the tank 41; the drain pipe 46 is connected to the inclined side wall of the liquid collection hopper 411, and the height of the connection port is higher than the bottom of the liquid collection hopper 411, so that a sedimentation zone is formed at the bottom of the liquid collection hopper 411. With the above configuration, when cleaning the tank 41, insoluble impurities intercepted by the filter screen 461 and naturally settled by gravity can be fully mixed with the wastewater under the action of the high-speed flushing water flow, and discharged from the system together through the waste discharge pipe 49 at the bottom, thereby effectively avoiding the long-term accumulation of impurities in the tank 41.

[0046] In a preferred embodiment, see [reference] Figure 1 , 9The system also includes a filtration mechanism 8, which comprises a filter box 81 and a third pumping assembly 83. The inlet of the filter box 81 is connected to the waste discharge pipe 49, and at least one filter assembly 82 is installed inside the filter box 81. The filter assembly 82 can be made of filter cotton, filter screen, or a combination thereof, and the filtration precision increases progressively along the liquid flow direction to achieve gradient interception and deep filtration of insoluble impurities. The third pumping assembly 83 connects the first inlet pipe 42 to the outlet of the filter box 81 and is used to transport the wastewater treated by the filter assembly 82 back to the tank 41. Through the above configuration, online purification and recycling of urea solution are achieved. The wastewater discharged from the cleaning tank 41 flows to the filter box 81, where insoluble impurities are effectively intercepted by the filter assembly 82. The purified urea solution is then transported back to the tank 41 by the third pumping assembly 83, forming a closed loop, which improves the utilization rate of urea raw materials and demineralized water and reduces material waste.

[0047] It is important to understand that the concentration of the urea solution in tank 41 of the mixing tank 4 is generally 25%-35%. During system operation, the urea solution circulating back is diluted with a fixed amount of demineralized water during the cleaning stage, and its concentration can be accurately calculated using the known amount of demineralized water added. Simultaneously, the volume of urea solution that cannot be emptied from the bottom of tank 41 is fixed. Based on these two constant volumes, the actual mass of urea raw material contained in the solution returning to the tank can be calculated. In the next batch preparation, the system only needs to add fresh urea equal to the difference between the total required urea amount and the amount of urea returned, and replenish the corresponding amount of demineralized water to accurately prepare a urea mixture of the predetermined concentration. Therefore, using the returned urea solution does not affect the final solution concentration, ensuring its stability.

[0048] As described above, the first pumping assembly 31, the second pumping assembly 72, and the third pumping assembly 83 each include a transfer pump, connecting pipelines, flow meters installed on the pipelines, and electromagnetic switching valves, etc. Their specific connection and installation methods are conventional fluid transport technologies in the art, and those skilled in the art can perform conventional design and installation according to actual needs; therefore, they will not be described in detail here. Each pumping assembly can independently and reliably pump the corresponding liquid to a designated location within the system.

[0049] In a preferred embodiment, see [reference] Figure 2 , 5The drain pipe 46 is equipped with a backflushing pipe 462. The inlet end of the backflushing pipe 462 is connected to the second pumping assembly 72, and the outlet end is equipped with a third nozzle 463 facing the filter screen 461. The third nozzle 463 is used to spray medium-temperature demineralized water from the second water tank 7 when needed to backflush the filter screen 461 to remove impurities trapped on its surface and prevent the filter screen 461 from clogging. The lower end of the drain pipe 46 is connected to a first branch pipe 464 connected to the waste discharge pipe 49. The first branch pipe 464 is equipped with a first valve 465 to control its opening and closing. The side wall of the drain pipe 46 is connected to a second branch pipe 466 for discharging urea solution. The second branch pipe 466 is equipped with a second valve 467 to control its opening and closing. The first valve 465 and the second valve 467 can be electromagnetic valves.

[0050] The specific working process is as follows: During the mixing and stirring stage, both the first valve 465 and the second valve 467 are closed. During the urea solution discharge stage, the first valve 465 is closed and the second valve 467 is opened. At this time, the urea solution is filtered through the filter screen 461 and discharged to the boiler flue gas denitrification system through the drain pipe 46 and the second branch pipe 466. During the cleaning stage, the second valve 467 is closed and the first valve 465 is opened. At the same time, the backwash pipe 462 can be activated to backwash the filter screen 461. At this time, some of the wastewater and detached impurities generated by the backwash pipe 462 and the cleaning mechanism 48 are discharged through the waste discharge pipe 49, while the other part of the wastewater is discharged through the drain pipe 46 and the first branch pipe 464 into the waste discharge pipe 49. By switching the two valves, the discharge paths of the finished solution and the cleaning wastewater are distinguished, effectively preventing the urea solution diluted during cleaning or backwashing from being accidentally discharged into the boiler flue gas denitrification system.

[0051] It is understood that those skilled in the art can make equivalent substitutions or modifications based on the technical solution and inventive concept of this utility model, and all such substitutions or modifications should fall within the protection scope of the appended claims of this utility model.

Claims

1. A system for recovering and utilizing the hydrophobic waste heat of a dryer, characterized in that, include: A condensate drain pipe (1) is used to connect the condensate outlet of the steam indirect heating device of the dryer (11); The expansion container (2) has its inlet connected to the condensate drain pipe (1) for vapor-liquid separation of the high-temperature condensate from the dryer (11); The first water tank (3) is located below the expansion container (2), and the bottom of the expansion container (2) is connected to the top of the first water tank (3) through the first drain pipe (21); The mixing tank (4) includes: a tank body (41), a first water inlet pipe (42) connected to the tank body (41), and a liquid level sensor (43), a temperature sensor (44) and a stirring mechanism (45) disposed in the tank body (41); the first water inlet pipe (42) is used to input room temperature demineralized water into the tank body (41); The first pumping assembly (31) is connected between the tank body (41) and the first water tank (3) and is used to pump the high temperature condensate in the first water tank (3) into the tank body (41); A quantitative feeding mechanism (5) is located above the tank (41) and is used to quantitatively feed urea into the tank (41). The top of the second water tank (7) is connected to the bottom of the expansion container (2) via the second drain pipe (22); the second water tank (7) is connected to the second water inlet pipe (71), which is used to input room temperature demineralized water into the second water tank (7); The second pumping assembly (72) is connected between the second water tank (7) and the tank body (41) and is used to pump the medium-temperature condensate in the second water tank (7) into the tank body (41); the high-temperature condensate in the first water tank (3) is higher than the medium-temperature condensate in the second water tank (7); The tank (41) has a drain pipe (46) at the bottom for discharging the urea solution inside the tank (41).

2. The dryer waste heat recovery and utilization system according to claim 1, characterized in that, The quantitative feeding mechanism (5) includes a hopper (51), a feeding channel (52) located at the bottom of the hopper (51), and a roller (53) rotatably located in the feeding channel (52). The outer periphery of the roller (53) is provided with a plurality of grooves (531) distributed around its axis. The end of the feeding channel (52) is connected to a feed pipe (6) that communicates with the tank body (41). When the roller (53) rotates, its grooves (531) can receive and quantitatively discharge urea.

3. The dryer waste heat recovery and utilization system according to claim 2, characterized in that, The mixing tank (4) is configured as two, and the lower end of the material discharge channel (52) is connected to a three-way pipe (61). The two outlets of the three-way pipe (61) are respectively connected to the feed pipes (6) of the two mixing tanks (4). The three-way pipe (61) is provided with a swingable baffle (62) for selectively guiding urea to one of the mixing tanks (4).

4. The dryer waste heat recovery and utilization system according to claim 2, characterized in that, The mixing tank (4) also includes a sealing mechanism (47), and the feed pipe (6) extends downward into the tank body (41). The sealing mechanism (47) includes: The sealing plate (471) has a conical structure and is located below the feed pipe (6); The first lifting assembly (472) is located on the tank body (41) and drives the sealing plate (471) to rise and fall vertically to close or open the lower port of the feed pipe (6).

5. The dryer waste heat recovery and utilization system according to claim 1, characterized in that, The mixing tank (4) further includes a cleaning mechanism (48), which includes: The annular water supply pipe (481) is installed inside the tank (41) in a height-adjustable manner. The annular water supply pipe (481) is provided with a number of first nozzles (482) facing the inner wall of the tank (41) and a number of second nozzles (483) facing the bottom of the tank (41). The second lifting assembly (484) is located on the tank body (41) and is used to drive the annular water pipe (481) to rise and fall in the vertical direction; The third inlet pipe (485) connects the second pumping assembly (72) and the annular water supply pipe (481) to pump the medium-temperature condensate in the second water tank (7) to the annular water supply pipe (481). Among them, the drain pipe (46) is equipped with a filter screen (461) at one end inside the tank (41); the bottom of the tank (41) is connected to a waste pipe (49) for discharging the wastewater and insoluble impurities after cleaning.

6. The dryer waste heat recovery and utilization system according to claim 5, characterized in that, The bottom of the tank (41) is provided with a liquid collecting hopper (411) in the form of a funnel. The waste discharge pipe (49) is connected to the bottom of the liquid collection hopper (411); The drain pipe (46) is connected to the inclined side wall of the collection hopper (411), and the height of the connection port is higher than the bottom of the collection hopper (411).

7. The dryer waste heat recovery and utilization system according to claim 5, characterized in that, It also includes a filtration mechanism (8), which includes: The filter box (81) has its inlet end connected to the waste pipe (49), and at least one filter component (82) is provided inside the filter box (81). The third pumping assembly (83) is connected to the outlet of the first inlet pipe (42) and the filter box (81) and is used to transport the wastewater treated by the filter assembly (82) back to the tank (41).

8. The dryer waste heat recovery and utilization system according to claim 5, characterized in that, The drain pipe (46) is provided with a backflush pipe (462), the inlet end of the backflush pipe (462) is connected to the second pumping assembly (72), and the outlet end of the backflush pipe (462) is provided with a third nozzle (463) facing the filter screen (461). The lower end of the drain pipe (46) is connected to a first branch pipe (464) that communicates with the waste pipe (49), and the first branch pipe (464) is provided with a first valve (465) to control its opening and closing; the side wall of the drain pipe (46) is connected to a second branch pipe (466) for discharging urea solution, and the second branch pipe (466) is provided with a second valve (467) to control its opening and closing.

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