Urea melt liquid evaporation separation device

Abstract

The utility model belongs to a kind of urea molten liquid evaporation separation device;Including urea molten liquid evaporation shell and urea molten liquid separation shell, the bottom of urea molten liquid separation shell is fixedly connected with the top of urea molten liquid evaporation shell;The inside of urea molten liquid evaporation shell is equipped with several heat exchange pipelines, the bottom and top of heat exchange pipeline are equipped with the tube sheet for fixing several heat exchange pipelines respectively, and several heat exchange pipelines are communicated with the inside of urea molten liquid separation shell;With the purpose of energy saving and improving urea production efficiency, it also can realize the advantages of reducing equipment floor area and urea content of biuret.

Description

Technical Field

[0001] This utility model belongs to the technical field of urea production equipment, specifically a urea melt evaporation and separation device. Background Technology

[0002] Urea, as a neutral fertilizer, is suitable for various soils and plants. Its ease of use and minimal soil-damaging effects make it popular among farmers. In urea production, urine is depressurized and decomposed by the outlet regulating valve of the distillation column before entering the flash evaporation tank. After flash evaporation, the urine enters the urine tank and is then pumped to the evaporation system for concentration. The concentrated urine is then sent to the granulation tower to granulate into urea granules. The evaporation system in this process generally includes a primary evaporation separation section and a secondary evaporation separation section. The purpose of the evaporation separation section is mainly to concentrate the urine. A typical evaporation separation section includes an evaporation heater and an evaporation separator. In other words, urine is first heated by an evaporator heater, then transported to an evaporator separator to separate the gas phase and concentrate the liquid phase for subsequent processes. The transport of urine from the evaporator heater to the evaporator separator generates heat loss. In actual production, not only is insulation of the transport pipeline necessary, but the steam usage within the evaporator separator also needs to be increased to compensate for the urine temperature. Furthermore, it is well known that the formation of biuret (a condensate produced in the evaporator separator) is closely related to temperature and time; that is, higher temperatures and / or longer production times result in a greater amount of biuret produced. Therefore, the aforementioned urine transport process and the urea temperature compensation process within the evaporator separator undoubtedly increase the biuret content in the urea, resulting in lower quality urea granules. Utility Model Content

[0003] To overcome the above deficiencies, this utility model provides a urea melt evaporation and separation device to solve the technical problems existing in the prior art.

[0004] The technical solution adopted by this utility model to solve its technical problem is: A urea melt evaporation and separation device is disclosed. The device includes a urea melt evaporation shell and a urea melt separation shell. The bottom of the urea melt separation shell is fixedly connected to the top of the urea melt evaporation shell. The urea melt evaporation shell is provided with a plurality of heat exchange pipes inside. The bottom and top of the heat exchange pipes are respectively provided with tube sheets for fixing the plurality of heat exchange pipes. The plurality of heat exchange pipes are connected to the interior of the urea melt separation shell.

[0005] The beneficial effects of this utility model are as follows: This utility model is applicable to the first-stage evaporation and separation section and the second-stage evaporation and separation section in the urea production process. This utility model combines the two devices of evaporation heater and evaporation separator in the traditional technology into one, that is: the urea melt separation shell is set on the top of the urea melt evaporation shell, so that the urea passing through the urea melt evaporation shell directly enters the urea melt separation shell. The above process not only achieves the purpose of saving energy and improving urea production efficiency, but also reduces the equipment footprint and the biuret content in urea.

[0006] Preferably, the upper part of the plurality of heat exchange pipes and the corresponding top tube sheet are arranged in the lower inner part of the urea melt separation shell.

[0007] Preferably, the urea melt separation shell corresponding to the top of the plurality of heat exchange pipes is provided with a gas-distribution and liquid-collection section. The gas-distribution and liquid-collection section includes a gas-distribution platform in the middle, a funnel-shaped liquid-collecting component at the center of the gas-distribution platform, and a liquid-collecting pipe at the bottom of the liquid-collecting component.

[0008] Preferably, the gas separation platform is provided with several supports around its perimeter, and the bottom of the supports is detachably connected to the inner wall of the urea melt separation shell.

[0009] Preferably, the bottom of the urea melt evaporation shell is provided with a urea melt inlet pipe, the lower side of the urea melt separation shell is provided with a urea melt outlet pipe, and the top of the urea melt separation shell is provided with a gas phase outlet pipe; the side of the urea melt evaporation shell is provided with a first steam inlet pipe and a first condensate outlet pipe; a heating coil is provided outside the urea melt separation shell, the first end of the heating coil is provided with a second steam inlet pipe, and the end of the heating coil is provided with a second condensate outlet pipe.

[0010] Preferably, each of the plurality of heat exchange pipes is provided with a throttling plug at its bottom. The throttling plug is a frustum structure, and a central through hole is provided between the upper and lower bottom surfaces of the frustum structure. The ratio of the inner diameter of the central through hole to the inner diameter of the heat exchange pipe is 1:4 to 5.

[0011] Preferably, the upper part of the urea melt separation shell is provided with a spray unit for flushing the condensate, the gas distribution platform and the liquid collection component are an integral structure, and the top of the liquid collection component is provided with a filter screen connected to the gas distribution platform.

[0012] Preferably, the end of the liquid collection pipe is connected to the inlet pipe of the spraying unit and the outlet pipe of the urea melt, respectively.

[0013] Preferably, the spraying unit includes a main spraying pipe, which is connected to several branch spraying pipes. The branch spraying pipes extend from the top of the urea melt separation shell to the upper inner part of the urea melt separation shell. A rotatable nozzle is provided at the end of the branch spraying pipe, and a liquid baffle is provided on the urea melt separation shell corresponding to the top of the rotatable nozzle.

[0014] A urea melt evaporation and separation device manufactured according to the above scheme reduces the equipment footprint by placing the urea melt separation shell on top of the urea melt evaporation shell. Simultaneously, the heat exchange pipes inside the urea melt evaporation shell are connected to the interior of the urea melt separation shell, allowing urine after passing through the heat exchange pipes to directly enter the urea melt separation shell, thus avoiding urine transport, reducing heat loss, improving urea production efficiency, and reducing the biuret content in urea. Furthermore, this invention features a gas-liquid separation and liquid-collecting section at the top of the heat exchange pipes. When the urea melt separation shell and the urea melt evaporation shell are an integral structure, the bottom of the gas-liquid separation and liquid-collecting section prevents urine from splashing inside the urea melt separation shell at the heat exchange pipe outlet, while also enabling gas phase diversion to ensure effective gas-liquid separation. Furthermore, the liquid-collecting component can recover the condensed urine, avoiding... To prevent contact between the urine from the outlet of the heat exchange pipe or the heat exchange pipe itself, thus avoiding disruption to the normal operation of the urea melt evaporator; furthermore, a throttling plug is installed at the bottom of the heat exchange pipe, enabling simultaneous heating of the urine and improved urine throughput efficiency; simultaneously, the upper part of the heat exchange pipe is located in the lower inner part of the urea melt separation shell, allowing the urine from the heat exchange pipe to continue heating while conserving energy, and to adapt to the temperature inside the urea melt separation shell in advance, thus facilitating smooth gas-liquid separation of the urine; this invention also includes a spray unit for rinsing the polymer, preferably using the urea melt in the collection pipe to rinse the polymer at the top of the urea melt separation shell, thus removing the polymer without stopping the equipment; it achieves the goals of saving energy and improving urea production efficiency, while also reducing the equipment footprint and the biuret content in the urea. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of this utility model.

[0017] Figure 2 This is a schematic diagram of the internal structure of the urea melt evaporation shell of this utility model.

[0018] Figure 3 This is a schematic diagram of the gas distribution platform of this utility model.

[0019] Figure 4 This is a top view of the gas distribution platform of this utility model.

[0020] Figure 5 This is a schematic diagram showing the positional relationship between the heat exchange pipe and the throttling plug of this utility model.

[0021] Figure 6 This is a schematic diagram of the rinsing fluid flow of the spray unit of this utility model.

[0022] In the diagram: 1. Urea molten liquid evaporation shell; 2. Urea molten liquid separation shell; 3. Heat exchange pipe; 4. Tube sheet; 5. Gas distribution platform; 6. Liquid collection component; 7. Liquid collection pipe; 8. Support; 9. Urea molten liquid inlet pipe; 10. Urea molten liquid outlet pipe; 11. Gas phase outlet pipe; 12. First steam inlet pipe; 13. First condensate outlet pipe; 14. Heating coil; 15. Second steam inlet pipe; 16. Second condensate outlet pipe; 17. Throttling plug; 18. Central through hole; 19. Filter screen; 20. Main spray pipe; 21. Spray branch pipe; 22. Rotatable nozzle; 23. Liquid baffle plate. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0024] The following is in conjunction with the appendix Figure 1 , 2This application provides a further detailed description of a urea melt evaporation and separation device. The evaporation and separation device includes a urea melt evaporation shell 1 and a urea melt separation shell 2. The bottom of the urea melt separation shell 2 is fixedly connected to the top of the urea melt evaporation shell 1. The urea melt evaporation shell 1 is provided with a plurality of heat exchange pipes 3 inside. The bottom and top of the heat exchange pipes 3 are respectively provided with tube plates 4 for fixing the plurality of heat exchange pipes 3. The plurality of heat exchange pipes 3 are connected to the inside of the urea melt separation shell 2. This invention is applicable to the first and second stages of evaporation and separation in the urea production process. The invention uses a heat exchange pipe 3 inside the urea molten liquid evaporation shell 1 connected to the inside of the urea molten liquid separation shell 2. This allows the urea, heated by the heat exchange pipe 3, to directly enter the urea molten liquid separation shell 2 for gas-liquid separation. This process avoids heat loss during urea transportation and the need for temperature compensation of the urea in the urea molten liquid separation shell 2. The process features a small equipment footprint and allows for rapid completion of the above steps for urea. Furthermore, it reduces the biuret content in urea and improves the quality of urea products.

[0025] Furthermore, such as Figure 1 , 2 As shown, the upper parts of the plurality of heat exchange pipes 3 and the corresponding top tube sheet 4 are arranged in the lower inner part of the urea melt separation shell 2. In normal operation, the urea melt evaporation shell 1 generally needs to heat the urea melt to 135-145°C, and the temperature inside the urea melt separation shell 2 is generally 150-170°C. The above arrangement can utilize the heat in the urea melt separation shell 2 to heat the urine, thereby achieving energy saving. At the same time, it can allow the urine to adapt to the temperature inside the urea melt separation shell 2 in advance, so as to achieve a good gas-liquid separation effect.

[0026] Furthermore, such as Figure 1 , 3As shown, the urea melt separation shell 2 corresponding to the top of the plurality of heat exchange pipes 3 is provided with a gas distribution and liquid collection section. The gas distribution and liquid collection section includes a gas distribution platform 5 located in the middle. A funnel-shaped liquid collection component 6 is provided at the center of the gas distribution platform 5. A liquid collection pipe 7 is provided at the bottom of the liquid collection component 6. Under normal circumstances, the liquid level of urine in the urea melt separation shell 2 is at the lower part of the gas distribution platform 5. By setting up a gas distribution and liquid collection section, the bottom of the gas distribution and liquid collection section can prevent splashing when urine enters the urea melt separation shell 2 through the heat exchange pipe 3 (when urine splashes onto the inner wall of the urea melt separation shell 2, it is easy to form a crust on the inner wall). At the same time, it can also be diverted through the outside of the gas distribution platform 5 when the gas phase rises, so that the gas phase is evenly distributed to achieve a good gas-liquid separation effect. Furthermore, when the condensate of the gas phase falls, the condensed urine can be recovered through the gas distribution platform 5 and the liquid collection part 6 to prevent the condensed urine from contacting the urine from the heat exchange pipe outlet or the heat exchange pipe, which would affect the normal operation of the urea melt evaporator and evaporation separator.

[0027] Furthermore, such as Figure 1 , 3 As shown, the gas distribution platform 5 is surrounded by several supports 8, and the bottom of the supports 8 is detachably connected to the inner wall of the urea melt separation shell 2. The gas distribution platform 5, the liquid collection component 6, and the supports 8 described in this invention are preferably an integrated structure, and the material is preferably titanium. This configuration ensures structural stability. In actual use, the gas distribution and liquid collection section experiences significant scouring; when replacement is needed, it can be carried out through a detachable connection. The detachable connection can be a conventional method such as bolt connection or rivet connection.

[0028] Furthermore, such as Figure 1 , 2 As shown, the bottom of the urea melt evaporation shell 1 is provided with a urea melt inlet pipe 9, the lower side of the urea melt separation shell 2 is provided with a urea melt outlet pipe 10, and the top of the urea melt separation shell 2 is provided with a gas phase outlet pipe 11; the side of the urea melt evaporation shell 1 is provided with a first steam inlet pipe 12 and a first condensate outlet pipe 13; the outside of the urea melt separation shell 2 is provided with a heating coil 14, the first end of the heating coil 14 is provided with a second steam inlet pipe 15, and the end of the heating coil 14 is provided with a second condensate outlet pipe 16.

[0029] Furthermore, such as Figure 2 , 5As shown, the bottom of each of the plurality of heat exchange pipes 3 is provided with a throttling plug 17. The throttling plug 17 is a frustum structure. A central through hole 18 is opened between the upper and lower bottom surfaces of the frustum structure. The ratio of the inner diameter of the central through hole 18 to the inner diameter of the heat exchange pipe 3 is 1:4 to 5. The throttling plug 17 of this invention can increase the flow rate of urine while ensuring sufficient heating, thereby improving the production efficiency of urea granules and reducing the biuret content. The throttling plug 17 can be connected to the heat exchange pipe 3 by welding, and the throttling plug 17 can be easily positioned by setting it as a frustum structure. Furthermore, since the urea melt evaporation shell 1 and the urea melt separation shell 2 in this invention can be set as an integral structure, there is no heat loss. That is, the temperature of urine in the heat exchange pipe 3 and the urea melt separation shell 2 rises continuously. Based on this, this invention can, while meeting the urine heating requirements, allow the urea solution to pass through the invention quickly by setting the central through hole 18 and the inner diameter of the heat exchange pipe 3, thereby achieving the purpose of reducing the biuret content while improving the urea production efficiency.

[0030] Furthermore, such as Figure 1 , 4 As shown, the upper part of the urea melt separation shell 2 is equipped with a spray unit for flushing the condensate. The gas distribution platform 5 and the liquid collection component 6 are an integral structure. The top of the liquid collection component 6 is equipped with a filter screen 19 connected to the gas distribution platform 5. By setting the filter screen 19, the condensate can be prevented from falling directly into the liquid collection component 6 and causing blockage of the liquid collection pipe 7 when the spray unit flushes the condensate. At the same time, this utility model also utilizes the characteristic that urine can dissolve the condensate, so that the urine dissolves the condensate before entering the liquid collection pipe 7.

[0031] Furthermore, such as Figure 6 As shown, the end of the liquid collection pipe 7 is connected to the inlet of the spray unit and the outlet pipe 10 of the urea melt, respectively. The urine in the liquid collection pipe 7 of this invention can normally enter the next process through the urea melt outlet pipe 10, or be used as the rinsing liquid for the spray unit. When the urine is used as the rinsing liquid for the spray unit, by utilizing the high temperature of the urine and its ability to dissolve condensates, the condensates are removed by simultaneously rinsing and dissolving them. This not only achieves online removal of condensates (i.e., without equipment shutdown), but also improves the removal efficiency of condensates while saving energy.

[0032] Furthermore, such as Figure 1 , 6As shown, the spraying unit includes a main spraying pipe 20, which is connected to several branch spraying pipes 21. The branch spraying pipes 21 extend from the top of the urea melt separation shell 2 to its upper inner part. A rotatable nozzle 22 is provided at the end of each branch spraying pipe 21, and a liquid-blocking baffle 23 is provided on the urea melt separation shell 2 corresponding to the top of the rotatable nozzle 22. This invention uses a liquid-blocking baffle 23 at the gas phase outlet pipe 11 to intercept not only the liquid phase carried by the gas phase during gas phase separation but also the liquid phase during the spraying unit's flushing of the condensate, thus reducing raw material loss. The rotatable nozzle 22 in this invention increases the flushing range, effectively removing the condensate from the upper part of the urea melt separation shell 2 while reducing the number of branch spraying pipes 21. The rotatable nozzle 22 can be purchased directly from the market, and since it is not the focus of this invention, its structure will not be described in detail.

[0033] This invention also provides a concentration and separation method for a urea melt evaporation and separation device, which includes the following steps: Step 1: The molten urea from the urea section enters the bottom of the molten urea evaporator shell 1 through the molten urea inlet pipe 9, and enters the heat exchange pipe 3 through the central through hole 18 inside the throttling plug 17 for heat exchange. After heat exchange, the molten urea enters the molten urea separation shell 2 through the heat exchange pipe 3. Step 2: The gas distribution platform 5 and the liquid collection component 6 are set at the top of the heat exchange pipe 3. The bottom of the gas distribution platform 5 and the liquid collection component 6 can prevent the molten urea entering the urea melt separation shell 2 from splashing, while allowing the gas phase to rise along the outside of the gas distribution platform 5 and the liquid collection component 6 to achieve gas phase separation; the molten urea at the bottom of the urea melt separation shell 2 enters the subsequent process section through the molten urea outlet pipe 10. Step 3: The gas phase in the urea molten liquid separation shell 2 rises upward, and the condensed liquid phase falls downward under the action of gravity and is collected through the gas separation platform 5 and the liquid collection device 6. The collected urea molten liquid enters the urea molten liquid outlet pipe 10 through the liquid collection pipe 7. Step 4: After the urea melt separation shell 2 has been running, the top of the urea melt separation shell 2 is coated with condensate. At this time, the spray unit needs to be started to spray and rinse it. The urea melt in the liquid collection pipe 7 enters several spray branch pipes 21 through the main spray pipe 20, and the top of the urea melt separation shell 2 is rinsed by the several spray branch pipes 21 and their corresponding rotatable nozzles 22. Step 5: The solid and liquid phases after spraying and rinsing fall into the lower part of the urea melt separation shell 2 and enter the subsequent process section through the urea melt outlet pipe 10; Step 6: When the solid and liquid phases after spraying and rinsing fall into the gas distribution platform 5 and the liquid receiving unit 6, they are filtered through the filter screen 19. The liquid phase enters the liquid receiving unit 6, and the solid phase gradually dissolves and enters the liquid receiving unit 6 under the contact of the molten urea. Step 7: During operation, the droplets carried by the gas phase and the molten urea liquid during the spraying and rinsing of the condensate are collected by the baffle plate 23. The collected droplets are then collected and the above steps 5-6 are repeated.

[0034] The essence of this invention lies in reducing energy consumption in the urea solution evaporation section, improving urea production efficiency, and reducing the biuret content in urea, while also reducing the equipment footprint. Based on this, without altering the original urea heating and separation process, this invention combines the urea melt evaporation shell 1 and the urea melt separation shell 2. This allows the urea in the heat exchange pipe 3 of the urea melt evaporation shell 1 to be heated and then directly enter the urea melt separation shell 2 for gas-liquid separation. Furthermore, by setting up a gas-liquid separation section based on the aforementioned combined design, the influence between the urea vapor heating section and the urea vapor separation section can be avoided, while also achieving uniform gas phase distribution to improve the gas-liquid separation effect. Additionally, this invention includes a throttling plug 17 to accelerate the urea flow rate, thereby improving urea production efficiency while reducing the biuret content.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A device for evaporating and separating urea molten liquid, characterized in that: The device includes a urea melt evaporation shell (1) and a urea melt separation shell (2), with the bottom of the urea melt separation shell (2) fixedly connected to the top of the urea melt evaporation shell (1); The urea melt evaporation shell (1) is provided with several heat exchange pipes (3). The bottom and top of the heat exchange pipes (3) are respectively provided with tube plates (4) for fixing the heat exchange pipes (3). The heat exchange pipes (3) are connected to the interior of the urea melt separation shell (2).

2. The urea melt evaporation and separation device according to claim 1, characterized in that: The upper part of the plurality of heat exchange pipes (3) and the corresponding top tube sheet (4) are set in the lower part of the urea melt separation shell (2).

3. The urea molten liquid evaporation and separation device according to claim 1, characterized in that: The urea melt separation shell (2) corresponding to the top of the several heat exchange pipes (3) is provided with a gas separation and liquid collection section. The gas-distribution and liquid-collection section includes a gas-distribution platform (5) located in the middle, a funnel-shaped liquid-collecting component (6) located at the center of the gas-distribution platform (5), and a liquid-collecting pipe (7) located at the bottom of the liquid-collecting component (6).

4. The urea melt evaporation and separation device according to claim 3, characterized in that: The gas distribution platform (5) is surrounded by several supports (8), and the bottom of the supports (8) is detachably connected to the inner wall of the urea melt separation shell (2).

5. The urea melt evaporation and separation device according to claim 4, characterized in that: The bottom of the urea melt evaporation shell (1) is provided with a urea melt inlet pipe (9), the lower side of the urea melt separation shell (2) is provided with a urea melt outlet pipe (10), and the top of the urea melt separation shell (2) is provided with a gas phase outlet pipe (11). The urea melt evaporation shell (1) is provided with a first steam inlet pipe (12) and a first condensate outlet pipe (13) on its side. The urea melt separation shell (2) is provided with a heating coil (14) on the outside. The first end of the heating coil (14) is provided with a second steam inlet pipe (15), and the end of the heating coil (14) is provided with a second condensate outlet pipe (16).

6. The urea melt evaporation and separation device according to claim 5, characterized in that: The bottom of each of the heat exchange pipes (3) is provided with a throttling plug (17). The throttling plug (17) is a frustum structure. A central through hole (18) is opened between the upper and lower surfaces of the frustum structure. The ratio of the inner diameter of the central through hole (18) to the inner diameter of the heat exchange pipe (3) is 1:4 to 5.

7. The urea melt evaporation and separation device according to claim 5, characterized in that: The upper part of the urea melt separation shell (2) is provided with a spray unit for flushing the condensate. The gas distribution platform (5) and the liquid receiving component (6) are an integral structure, and the top of the liquid receiving component (6) is provided with a filter screen (19) connected to the gas distribution platform (5).

8. The urea melt evaporation and separation device according to claim 7, characterized in that: The end of the liquid collection pipe (7) is connected to the inlet of the spray unit and the outlet pipe (10) of the urea melt, respectively.

9. A urea melt evaporation and separation device according to claim 7 or 8, characterized in that: The spraying unit includes a main spraying pipe (20), which is connected to several branch spraying pipes (21). The branch spraying pipes (21) extend from the top of the urea melt separation shell (2) to the upper inner part of the urea melt separation shell (2). A rotatable nozzle (22) is provided at the end of the branch spraying pipe (21), and a liquid baffle (23) is provided on the urea melt separation shell (2) corresponding to the top of the rotatable nozzle (22).

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