Novel heating and cooling control system of urea synthesis tower

Abstract

The utility model discloses a novel heating and cooling control system for a urea synthesis tower, which relates to the technical field of urea synthesis towers and comprises a heating system and a cooling system which are respectively communicated with the bottom and the top of the urea synthesis tower. The heating system comprises a top heating pipeline and a bottom heating pipeline, the top heating pipeline is communicated with a material outlet in the top of the urea synthesis tower, and the bottom heating pipeline is communicated with a liquid discharge port in the bottom of the urea synthesis tower; the cooling system comprises a condensation liquid inlet pipeline at the top and a condensation gas inlet pipeline at the bottom, the condensation liquid inlet pipeline is communicated with the top heating pipeline, and the condensation gas inlet pipeline is communicated with a liquid discharge port at the bottom of the urea synthesis tower. The device is reasonable in design, the upper part and the lower part of the synthesis tower are simultaneously heated and cooled, the temperature of each point of the synthesis tower is uniformly and synchronously increased and decreased, and the temperature difference between the lining and the barrel is less than 30 DEG C.

Description

Technical Field

[0001] This utility model relates to the field of urea synthesis tower technology, and more specifically to the field of a novel temperature control system for urea synthesis tower. Background Technology

[0002] Patent publication number CN101270065B, entitled "A Urea Synthesis Tower Tray," discloses the following: A urea synthesis tower tray. This urea synthesis tower tray includes a tray body installed inside a urea synthesis tower. Circular through-holes are distributed on the tray body, and cylindrical caps cover the through-holes. Multiple narrow slots are cut into the top plate of the cap, and these slots are arranged in a radiating pattern. One edge of the cut-off portion of each slot remains connected to the top plate of the cap. The cut-off portion is bent downwards to form fins with a certain angle to the plane of the top plate. This invention has a reasonable structure and can improve the flowability of the distributed material in the urea synthesis tower and increase the reaction conversion rate.

[0003] As urea production technology becomes more sophisticated, cost reduction and efficiency improvement have become new directions for technological innovation. The aforementioned patents and existing technologies must consider the following two important factors during the initial start-up, long-term shutdown start-up, and long-term shutdown cooling processes of urea production, resulting in slower efficiency and higher consumption. These two factors are as follows:

[0004] The lining and cylinder system of the urea synthesis tower are composed of two materials: 316L lining and carbon steel cylinder. If the heating and cooling rates are too fast, the expansion coefficients of the two materials will be inconsistent, which will cause damage to the lining. The heating and cooling rate must be controlled to not exceed 10 degrees Celsius / hour to prevent equipment damage.

[0005] 2. When cooling the synthesis tower, the airflow velocity inside the synthesis tower must be limited to prevent the tower plates from being blown over.

[0006] Therefore, designing novel heating and cooling schemes for urea synthesis towers to improve heating and cooling efficiency is of practical significance to those skilled in the art. Utility Model Content

[0007] The purpose of this utility model is to provide a novel temperature control system for urea synthesis towers in order to solve the above-mentioned technical problems.

[0008] To achieve the above objectives, this utility model specifically adopts the following technical solution:

[0009] One aspect of this utility model provides a novel heating and cooling control system for a urea synthesis tower, comprising a heating system and a cooling system, wherein the heating system and the cooling system are respectively connected to the bottom and top of the urea synthesis tower.

[0010] The heating system includes a top heating pipe and a bottom heating pipe. The top heating pipe is connected to the material outlet at the top of the urea synthesis tower, and the bottom heating pipe is connected to the liquid discharge port at the bottom of the urea synthesis tower.

[0011] The cooling system includes a top condensate inlet pipe and a bottom condensate inlet pipe. The condensate inlet pipe is connected to the top heating pipe, and the condensate inlet pipe is connected to the bottom drain port of the urea synthesis tower.

[0012] Specifically, the synthesis tower employs a simultaneous heating and cooling method at both the top and bottom to ensure uniform and synchronous temperature rise and fall at all points within the tower, with a temperature difference of less than 30°C between the lining and the shell. Shutdown is achieved using corrosion-resistant air cooling at the bottom of the tower, which simultaneously cools the lining and shell, shortening the cooling time and saving maintenance time, thus providing a reliable guarantee for the unit's high-efficiency production capacity.

[0013] The heating process is as follows: Steam from the top heating pipe enters the top shell side of the synthesis tower. Liquid water at the bottom of the synthesis tower is discharged through the drain port. After the liquid water at the bottom of the synthesis tower is drained, the bottom heating pipe connects to the drain port, heating the bottom shell side of the synthesis tower simultaneously. This simultaneous heating at the bottom and top ensures that the temperature difference between the synthesis tower lining and the synthesis tower shell is less than 30°C. The steam liquefies within the shell side of the synthesis tower and then exits the synthesis tower through the drain port.

[0014] The cooling process is as follows: Before cooling, the temperature inside the synthesis tower is about 180℃. First, steam is introduced into the top shell side of the synthesis tower through the top heating pipe to drain the liquid water at the bottom of the tower. Then, condensate is added into the synthesis tower in stages through the condensate inlet pipe and the material outlet at the top of the synthesis tower (the temperature of the condensate in stages is 150℃, 120℃, 100℃, and 70℃). Then, it is discharged through the drain port. When the temperature inside the synthesis tower drops to 70-80℃, the condensate inlet pipe is connected to the drain port, and air is injected into the bottom of the synthesis tower through the drain port to slowly cool it down.

[0015] In one embodiment, valves 1, 3, 4 and 5 are sequentially arranged on the top heating pipe, and a material discharge pipe is connected to the top heating pipe between valves 4 and 5. The material discharge pipe is equipped with valve 6; the condensate inlet pipe is connected to the top heating pipe between valves 1 and 3.

[0016] Specifically, pressure gauges PI 0216 and PI 0213 are installed on the top heating pipe. PI 0216 is located at the front end of valve one, and pressure gauge PI 0213 is located at the rear end of valve one.

[0017] In one embodiment, a main drain pipe is connected to the drain port, and valves 23, 25 and 24 are sequentially installed on the main drain pipe. The bottom heating pipe is connected to valve 25, and the condensate inlet pipe is connected to valve 24.

[0018] Specifically, a pressure gauge PI 0211 is installed on the main drainage pipeline, and the pressure gauge PI 0211 is located between valve twenty-three and valve twenty-five.

[0019] In one embodiment, a valve and a pressure gauge are installed on the condensate inlet pipe.

[0020] Specifically, the condensate inlet pipe is equipped with valve two and pressure gauge PI 0214.

[0021] Another aspect of this utility model provides a urea synthesis tower, including a tower body, a tube set inside the tower body, a material inlet set at the top of the tower body, a material outlet set at the top of the tower body, and a drain port set at the bottom of the tower body. The material inlet is connected to the tube side inlet of the tube set, and the material outlet is connected to the shell side outlet of the tube set.

[0022] In one embodiment, a pressure gauge is installed at the top of the tower body, and multiple temperature detection gauges are installed at equal intervals on the side walls of the tower body.

[0023] Specifically, a pressure gauge PI 0203 is installed at the top of the tower body, and temperature gauges TR0202, TR0204, TR0205, TR0206 and TR0203 are installed in sequence from top to bottom of the tower body.

[0024] In one embodiment, it also includes a liquid ammonia feed pipe, a methyl ammonium liquid feed pipe and a carbon dioxide gas inlet pipe. One end of the liquid ammonia feed pipe is connected to the material inlet through the main liquid inlet pipe, and the other end is connected to the drain port through the auxiliary liquid inlet pipe.

[0025] The ammonium carbamate liquid feed pipe is connected to the middle of the main liquid inlet pipe, and the carbon dioxide gas inlet pipe is connected to the main liquid inlet pipe at the end near the material inlet.

[0026] Specifically, valves thirteen, fourteen, and a check valve are installed sequentially on the main inlet pipe; valves fifteen, sixteen, and seventeen are installed sequentially on the second flushing branch pipe; regulating valves (flow valve FRC02020, flow valve FT0202), twenty-two, twenty-one, and a check valve are installed sequentially on the auxiliary inlet pipe; valve twelfth and a check valve are installed sequentially on the ammonium carbamate inlet pipe; and valves tenth, eleventh, and a check valve are installed sequentially on the carbon dioxide inlet pipe.

[0027] In one embodiment, the system further includes a flushing pipeline system, which includes a main flushing pipeline, a first flushing branch pipeline, a second flushing branch pipeline, and a third flushing branch pipeline, all of which are connected to the main flushing pipeline. The first flushing branch pipeline is connected to a carbon dioxide inlet pipe, the second flushing branch pipeline is connected to a main liquid inlet pipe, and the third flushing branch pipeline is connected to an auxiliary liquid inlet pipe.

[0028] Specifically, valves seven, eight, and nine are installed on the first flushing branch pipe; valves fifteen, sixteen, and seventeen are installed on the second flushing branch pipe; and valves eighteen, nineteen, and twentieth, along with pressure gauge P I0210, are installed on the third flushing branch pipe.

[0029] In one implementation, the inlet of the main flushing pipe is connected to the condensate inlet pipe.

[0030] The beneficial effects of this utility model are as follows:

[0031] 1. This utility model design and layout employs a simultaneous heating and cooling method for the synthesis tower, ensuring uniform and synchronous temperature rise and fall at all points within the tower, with a temperature difference of less than 30°C between the lining and the shell. Shutdown is achieved using a corrosion-resistant air cooling method at the bottom of the tower, which simultaneously cools the lining and shell, shortening the cooling time and saving maintenance time, thus providing a reliable guarantee for the unit's high-efficiency production capacity.

[0032] 2. It is more conducive to the safe, environmentally friendly, and long-term operation of the plant. It plays a protective role for key equipment. Maintenance and repair work time is significantly reduced, greatly improving productivity while ensuring safety and environmental protection. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0035] To make the technical problems, technical solutions, and technical effects of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0037] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0038] In the description of the embodiments of this utility model, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use. They 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 be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0039] Example 1

[0040] This embodiment provides a urea synthesis tower, including a tower body, tubes disposed within the tower body, a material inlet disposed at the top of the tower body, a material outlet disposed at the top of the tower body, and a drain port disposed at the bottom of the tower body. The material inlet is connected to the tube side inlet of the tubes, and the material outlet is connected to the shell side outlet of the tubes.

[0041] A pressure gauge is installed at the top of the tower, and multiple temperature gauges are installed at equal intervals on the side walls of the tower.

[0042] Specifically, a pressure gauge PI 0203 is installed at the top of the tower body, and temperature gauges TR0202, TR0204, TR0205, TR0206 and TR0203 are installed in sequence from top to bottom of the tower body.

[0043] It also includes a liquid ammonia feed pipe, a carbamate liquid feed pipe and a carbon dioxide gas inlet pipe. One end of the liquid ammonia feed pipe is connected to the material inlet through the main liquid inlet pipe, and the other end is connected to the drain port through the auxiliary liquid inlet pipe.

[0044] The ammonium carbamate liquid feed pipe is connected to the middle of the main liquid inlet pipe, and the carbon dioxide gas inlet pipe is connected to the main liquid inlet pipe at the end near the material inlet.

[0045] Specifically, valves thirteen, fourteen, and a check valve are installed sequentially on the main inlet pipe; valves fifteen, sixteen, and seventeen are installed sequentially on the second flushing branch pipe; regulating valves (flow valve FRC02020, flow valve FT0202), twenty-two, twenty-one, and a check valve are installed sequentially on the auxiliary inlet pipe; valve twelfth and a check valve are installed sequentially on the ammonium carbamate inlet pipe; and valves tenth, eleventh, and a check valve are installed sequentially on the carbon dioxide inlet pipe.

[0046] It also includes a flushing pipeline system, which includes a main flushing pipeline, a first flushing branch pipeline, a second flushing branch pipeline, and a third flushing branch pipeline, all of which are connected to the main flushing pipeline. The first flushing branch pipeline is connected to the carbon dioxide inlet pipe, the second flushing branch pipeline is connected to the main liquid inlet pipe, and the third flushing branch pipeline is connected to the auxiliary liquid inlet pipe.

[0047] Specifically, valves seven, eight, and nine are installed on the first flushing branch pipe; valves fifteen, sixteen, and seventeen are installed on the second flushing branch pipe; and valves eighteen, nineteen, and twentieth, along with pressure gauge P I0210, are installed on the third flushing branch pipe.

[0048] The inlet of the main flushing pipe is connected to the condensate inlet pipe.

[0049] Example 2

[0050] like Figure 1 As shown, this embodiment provides a novel heating and cooling control system for a urea synthesis tower, including a heating system and a cooling system, which are respectively connected to the bottom and top of the urea synthesis tower.

[0051] The heating system includes a top heating pipe and a bottom heating pipe. The top heating pipe is connected to the material outlet at the top of the urea synthesis tower, and the bottom heating pipe is connected to the liquid discharge port at the bottom of the urea synthesis tower.

[0052] The cooling system includes a top condensate inlet pipe and a bottom condensate inlet pipe. The condensate inlet pipe is connected to the top heating pipe, and the condensate inlet pipe is connected to the bottom drain port of the urea synthesis tower.

[0053] Specifically, the synthesis tower employs a simultaneous heating and cooling method at both the top and bottom to ensure uniform and synchronous temperature rise and fall at all points within the tower, with a temperature difference of less than 30°C between the lining and the shell. Shutdown is achieved using corrosion-resistant air cooling at the bottom of the tower, which simultaneously cools the lining and shell, shortening the cooling time and saving maintenance time, thus providing a reliable guarantee for the unit's high-efficiency production capacity.

[0054] The heating process is as follows: Steam from the top heating pipe enters the top shell side of the synthesis tower. Liquid water at the bottom of the synthesis tower is discharged through the drain port. After the liquid water at the bottom of the synthesis tower is drained, the bottom heating pipe connects to the drain port, heating the bottom shell side of the synthesis tower simultaneously. This simultaneous heating at the bottom and top ensures that the temperature difference between the synthesis tower lining and the synthesis tower shell is less than 30°C. The steam liquefies within the shell side of the synthesis tower and then exits the synthesis tower through the drain port.

[0055] The cooling process is as follows: Before cooling, the temperature inside the synthesis tower is about 180℃. First, steam is introduced into the top shell side of the synthesis tower through the top heating pipe to drain the liquid water at the bottom of the tower. Then, condensate is added into the synthesis tower in stages through the condensate inlet pipe and the material outlet at the top of the synthesis tower (the temperature of the condensate in stages is 150℃, 120℃, 100℃, and 70℃). Then, it is discharged through the drain port. When the temperature inside the synthesis tower drops to 70-80℃, the condensate inlet pipe is connected to the drain port, and air is injected into the bottom of the synthesis tower through the drain port to slowly cool it down.

[0056] Example 3

[0057] This embodiment is a further optimization based on embodiment 2, specifically:

[0058] The top heating pipe is equipped with valves 1, 3, 4 and 5 in sequence. A material discharge pipe is connected to the top heating pipe between valves 4 and 5. The material discharge pipe is equipped with valve 6. The condensate inlet pipe is connected to the top heating pipe between valves 1 and 3.

[0059] Specifically, pressure gauges PI 0216 and PI 0213 are installed on the top heating pipe. PI 0216 is located at the front end of valve one, and pressure gauge PI 0213 is located at the rear end of valve one.

[0060] The drain port is connected to a main drain pipe, which is equipped with valves 23, 25 and 24 in sequence. The bottom heating pipe is connected to valve 25, and the condensate inlet pipe is connected to valve 24.

[0061] Specifically, a pressure gauge PI 0211 is installed on the main drainage pipeline, and the pressure gauge PI 0211 is located between valve twenty-three and valve twenty-five.

[0062] A valve and a pressure gauge are installed on the condensate inlet pipe.

[0063] Specifically, the condensate inlet pipe is equipped with valve two and pressure gauge PI 0214.

[0064] The heating process for the synthesis tower is as follows:

[0065] S1. Open the valves: Valve 1, Valve 4, Valve 5, Valve 23, Valve 25.

[0066] S2. Close valves: Valve 2, Valve 3, Valve 6, Valve 21, Valve 24.

[0067] S3. After draining the condensate through valves one and three in the steam pipeline, close valve three. Slightly open valve four to slowly introduce steam, controlling the temperature at a rate of 6-8℃ / h, with TR0202 as the reference point, keeping the temperature below 100℃. During operation, avoid significant temperature fluctuations. Initially, the wall temperature TR0204 will not change.

[0068] S4. When the temperature TR0204 rises, the temperature difference with TR0202 should be within 30℃. Control the heating rate. If the heating rate is too fast, close the steam valve. If the heating rate is slow, the steam volume can be increased slowly, but do not rush to prevent the steam volume from being too large and the temperature from rising suddenly.

[0069] When the temperatures of S5, TR0202 and TR0204 are close, they should be stabilized for a period of time. Do not rush to open the steam valve to prevent the temperature of TR0205 from rising suddenly. The temperature rise rate of TR0205 should still be 6-8℃ / h, and the temperature at this point should be controlled to slowly approach TR0204.

[0070] When approaching S6, TR0202, TR0204, and TR0205, it is still necessary to prevent a sudden temperature rise in TR0206.

[0071] S7. When the temperature at each point of the urea synthesis tower reaches 90-100℃, adjust the bottom drain valve 25 to slowly increase the pressure of the urea synthesis tower and continuously discharge the steam condensate. Note that a large amount of liquid should not accumulate at the bottom of the tower.

[0072] S8. At this point, still use temperature TR0202 as the standard and control the heating rate to 6-8℃ / h. At the same time, pay attention to the temperature rise at TR0205 and TR0206.

[0073] S9. If the above three points are heated according to the regulations, it means that the preheating is normal. Then continue to preheat the temperature of each point to 150℃.

[0074] S10. Once the temperature at each point has reached 150℃, if the material is not fed into the tower immediately, continue to supply an appropriate amount of steam to maintain the temperature of the synthesis tower and be ready to start the tower at any time.

[0075] S11. After the start-up preparations are complete, stop the steam supply, close the four valves (valve one and valve four) for steam entering the synthesis tower, and close the bottom discharge valve (valve twenty-five).

[0076] Synthesis tower temperature rise data:

[0077]

[0078]

[0079] The cooling process for the synthesis tower is as follows:

[0080] S1. Open the valves: Valve 3, Valve 4, Valve 5, Valve 23, Valve 25.

[0081] S2. Close the valves: Valve 1, Valve 2, Valve 6, Valve 21, Valve 24.

[0082] S3. Connect the anti-corrosion air to the drain outlet of valve 25. Slightly open valve 25 and slowly introduce anti-corrosion air. Control the temperature drop rate at 6-8℃ / h, using TR0203 as a reference. During operation, be careful not to cause large temperature fluctuations.

[0083] S4. Also pay attention to the cooling status of TR204, TR0205, and TR0206.

[0084] Synthesis tower cooling data:

[0085]

[0086] Example 4

[0087] This embodiment uses a pre-maintenance start-up and shutdown as an example. After the unit is shut down for replacement, the cooling rate is below 8-10℃ / s, and the cooling time is 34 hours, saving 46 hours compared to the previous cooling time. During the unit startup, the synthesis tower heating rate is 8℃ / s, taking 22 hours while protecting the synthesis tower, which is 30 hours shorter than the previous tower top heating. The annual pre-maintenance will be completed in approximately 3 days less time. While protecting the equipment, this saves maintenance costs, greatly improves productivity, and lays the foundation for the safe, environmentally friendly, stable, and long-term operation of the unit.

Claims

1. A new temperature control system for a urea synthesis tower, characterized in that, The temperature rising system and the temperature falling system are communicated with the bottom and the top of the urea synthesis tower respectively; The temperature rising system comprises a top temperature rising pipeline and a bottom temperature rising pipeline, the top temperature rising pipeline is communicated with the material outlet at the top of the urea synthesis tower, and the bottom temperature rising pipeline is communicated with the liquid discharge port at the bottom of the urea synthesis tower. The temperature falling system comprises a top condensing liquid inlet pipeline and a bottom condensing gas inlet pipeline, the condensing liquid inlet pipeline is communicated with the top temperature rising pipeline, and the condensing gas inlet pipeline is communicated with the liquid discharge port at the bottom of the urea synthesis tower.

2. The new temperature control system for urea synthesis tower according to claim 1, characterized in that, Valve one, valve three, valve four and valve five are sequentially arranged on the top temperature rising pipeline, a material discharge pipeline is connected to the top temperature rising pipeline between valve four and valve five, and valve six is arranged on the material discharge pipeline.

3. The new temperature control system for urea synthesis tower according to claim 2, characterized in that, The liquid discharge main pipeline is connected to the liquid discharge port, and valve twenty-three, valve twenty-five and valve twenty-four are sequentially arranged on the liquid discharge main pipeline, the bottom temperature rising pipeline is communicated with valve twenty-five, and the condensing gas inlet pipeline is communicated with valve twenty-four.

4. The new temperature control system for urea synthesis tower according to claim 3, characterized in that, Valve two and a pressure gauge are arranged on the condensing liquid inlet pipeline.

5. A urea synthesis tower characterized by, The urea synthesis tower new temperature rising and falling control system comprises the urea synthesis tower and the temperature rising and falling control system.

6. A urea synthesis tower according to claim 5, characterized in that The urea synthesis tower comprises a tower body, a tube bank arranged in the tower body, a material inlet arranged at the top of the tower body, a material outlet arranged at the top of the tower body and a liquid discharge port arranged at the bottom of the tower body, the material inlet is communicated with the tube side inlet of the tube bank, and the material outlet is communicated with the shell side outlet of the tube bank.

7. A urea synthesis tower according to claim 6, characterized in that A pressure gauge is arranged at the top of the tower body, and a plurality of temperature detection gauges are equidistantly arranged on the side wall of the tower body.

8. A urea synthesis tower according to claim 6, characterized in that The urea synthesis tower further comprises a liquid ammonia feeding pipeline, a methylamine liquid feeding pipeline and a carbon dioxide gas feeding pipeline, one end of the liquid ammonia feeding pipeline is communicated with the material inlet through a main liquid feeding pipeline, and the other end of the liquid ammonia feeding pipeline is communicated with the liquid discharge port through a secondary liquid feeding pipeline; The methylamine liquid feeding pipeline is communicated with the middle part of the main liquid feeding pipeline, and the carbon dioxide gas feeding pipeline is connected to the main liquid feeding pipeline close to the material inlet.

9. A urea synthesis tower according to claim 8, characterized in that The urea synthesis tower further comprises a flushing pipeline system, the flushing pipeline system comprises a flushing main pipeline, a first flushing branch pipeline, a second flushing branch pipeline and a third flushing branch pipeline which are all communicated with the flushing main pipeline, the first flushing branch pipeline is communicated with the carbon dioxide gas feeding pipeline, the second flushing branch pipeline is communicated with the main liquid feeding pipeline, and the third flushing branch pipeline is communicated with the secondary liquid feeding pipeline.

10. A urea synthesis tower according to claim 9, characterized in that The liquid inlet of the flushing main pipeline is communicated with the condensing liquid inlet pipeline.

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