Horizontal high-pressure methylamine full-condensation reactor and CO2 stripping method urea production system

Abstract

The application discloses a horizontal high-pressure methylamine full-condensation reactor and a CO2 gas stripping method urea production system. The application adopts a special horizontal high-pressure methylamine condensation reactor and a unique urea high-pressure ring process flow, realizes that the two-step reactions of urea are carried out under the best conditions, and solves the problems of low conversion rate, low by-product steam pressure, high energy consumption and high civil framework of the traditional CO2 gas stripping method urea process. The application has the advantages of simple process, high conversion rate, low energy consumption and low framework.

Description

Technical Field

[0001] This invention relates to an industrial urea production process and specialized equipment, specifically a novel CO2 stripping urea production process and a horizontal high-pressure ammonium carbamate total condensation reactor. Background Technology

[0002] Industrial urea production uses CO2 gas and liquid ammonia as raw materials, and processes them into solid urea products through high-pressure synthesis, medium-pressure and / or low-pressure decomposition and recovery, vacuum concentration, granulation and other processes.

[0003] The traditional high-pressure process of CO2 stripping involves feeding raw CO2 gas into a high-pressure stripping tower. The gas decomposed from the high-pressure stripping tower enters a falling film high-pressure condenser, where it is condensed and absorbed by liquid ammonia and ammonium carbamate from a high-pressure scrubber to generate a reaction liquid and gas. Then, the gas and liquid flow together into the urea synthesis tower for reaction using the pressure difference. The reaction liquid from the urea synthesis tower returns to the top of the high-pressure stripping tower for decomposition using the level difference before entering the next process. Unreacted gas enters the high-pressure scrubber for condensation and absorption before being discharged.

[0004] The above-mentioned urea production process has the following problems: 1. Since the reaction liquid from the urea synthesis tower returns to the top of the high-pressure stripping tower using a pressure difference, the bottom inlet of the urea synthesis tower must be at least 10m higher than the top liquid inlet of the high-pressure stripping tower; 2. Because the high-pressure condenser uses a falling film type, the ammonium carbamate solution and stripping gas (CO2 and NH3) enter from the top, while the reaction liquid and gas are discharged from the bottom and sent back to the urea synthesis tower using a pressure difference. Therefore, the bottom of the high-pressure condenser must be at least at the same height as the bottom of the urea synthesis tower. As a result, the urea synthesis tower (bottom) and the high-pressure ammonium carbamate condenser (bottom) must be arranged on a plane with a height of about 20m, making its civil engineering frame as high as 50-70m. Not only is the investment in the equipment high, but operation, management, and maintenance are also relatively difficult.

[0005] Furthermore, the high-pressure condenser, a key piece of equipment in the traditional CO2 stripping process, primarily employs a membrane-falling structure. The process material (consisting of gas and liquid) flows downwards from the tube side of the condenser, while the steam condensate flows through the shell side. With the high-pressure process material flowing through the tubes, the liquid forms a thin film on the tube wall due to the downward flow of gas and liquid, while the gas travels within the tubes. This results in a very short residence time for the process material within the tubes, with a material temperature of approximately 167°C. The steam pressure produced as a byproduct on the shell side is low, typically 0.34 MPa (G), making it difficult to utilize efficiently. Because of the short residence time and lack of a reaction zone within the tubes, no urea is generated within the high-pressure condenser, necessitating a large-volume urea synthesis tower to achieve a high conversion rate.

[0006] In addition, since the high-pressure ammonium carbamate condenser is a vertical shell-and-tube heat exchanger, its shell-side space is limited, making it impossible to achieve vapor-liquid separation of by-product steam. A separate separation steam drum must be set up, which leads to the problem of large equipment footprint and difficult layout. Summary of the Invention

[0007] The purpose of this invention is to address the problems existing in the prior art by providing a novel CO2 stripping urea production process. By improving the high-pressure coil process of the traditional CO2 stripping urea process, the height of major high-pressure equipment such as the urea synthesis tower can be significantly reduced while increasing the urea synthesis conversion rate. Equipment such as the low-pressure steam drum can be eliminated, thereby reducing equipment investment and simplifying installation and maintenance.

[0008] The present invention also provides a horizontal high-pressure ammonium carbamate total condensation reactor for use in the production process of the present invention.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a horizontal high-pressure ammonium carbamate total condensation reactor, comprising: a horizontally arranged condensation section and a plug flow reaction section;

[0010] The condensation section is a kettle-type reboiler with a horizontally placed U-shaped heat exchange tube bundle on the shell side; the plug flow reaction section is connected to the outlet of the U-shaped heat exchange tube bundle, and several vertically arranged guide trays are installed in the plug flow reaction section.

[0011] The reactants enter the U-shaped heat exchange tube bundle in the condensation section, where they exchange heat with the steam condensate in the shell side and achieve uniform mixing of the reactants before entering the plug flow reaction section for reaction.

[0012] Furthermore, the upper part of the condensing section is provided with a reactant inlet that communicates with the inlet of the U-shaped heat exchange tube bundle, while the steam condensate inlet and outlet that communicate with the shell side are respectively located at the lower and upper parts of the condensing section.

[0013] Furthermore, a redistribution chamber is provided at the inlet of the U-shaped heat exchange tube bundle, and a redistribution element for optimizing fluid distribution is provided in the redistribution chamber.

[0014] Furthermore, an air inlet is provided at the bottom of the connection between the plug flow reaction section and the condensation section, and the air inlet is connected to a tubular gas distributor installed inside the plug flow reaction section.

[0015] Furthermore, a gas-liquid separation chamber is provided at the end of the plug flow reaction section to separate the reaction products into gas and liquid. A gas outlet is provided at the upper part of the end, and a reaction liquid outlet is provided at the lower part. The separated gas and liquid are discharged from the gas outlet and the reaction liquid outlet, respectively.

[0016] A CO2 stripping urea production system includes: the aforementioned horizontal high-pressure ammonium carbamate total condensation reactor, urea synthesis tower, and high-pressure stripping tower;

[0017] The reaction liquid outlet of the horizontal high-pressure ammonium carbamate total condensation reactor is connected to the reaction liquid inlet at the bottom of the urea synthesis tower. The reaction products of the horizontal high-pressure ammonium carbamate total condensation reactor, ammonium carbamate and urea, react with the raw material liquid ammonia and compressed CO2 gas from the bottom into the urea synthesis tower.

[0018] The reactant liquid outlet of the urea synthesis tower is connected to the pipe-side inlet of the high-pressure stripping tower, and the reactant gas outlet at the top of the urea synthesis tower is connected to the gas inlet of the horizontal high-pressure ammonium carbamate total condensation reactor. Unreacted CO2 and NH3 gases enter the horizontal high-pressure ammonium carbamate total condensation reactor through the gas outlet.

[0019] The stripping gas from the high-pressure stripping tower, together with the added ammonium carbamate solution, enters from the reactant inlet of the horizontal high-pressure ammonium carbamate total condensation reactor. CO2 and NH3 are condensed and absorbed, and the reaction produces ammonium carbamate and urea.

[0020] The reaction liquid in the urea synthesis tower enters from the top of the high-pressure stripping tower, while the compressed CO2 gas from the raw material enters from the bottom of the high-pressure stripping tower. The ammonium carbamate in the reaction liquid is decomposed into NH3 and CO2 gas and sent to the U-shaped heat exchange tube bundle section of the horizontal high-pressure ammonium carbamate total condensation reactor. Urea is discharged from the bottom of the high-pressure stripping tower.

[0021] Furthermore, the system also includes a high-pressure scrubber. Unreacted CO2 and NH3 gases from the horizontal high-pressure ammonium carbamate total condensation reactor enter through the top inlet of the high-pressure scrubber and are washed with the added ammonium carbamate solution to recover NH3 and CO2. The generated ammonium carbamate solution overflows from the high-pressure scrubber into the horizontal high-pressure ammonium carbamate total condensation reactor.

[0022] Furthermore, the urea synthesis tower is located on the ground, the bottom of the high-pressure stripping tower is located within 2m of the ground, the bottom of the high-pressure scrubber is at least 10m above the top of the horizontal high-pressure ammonium carbamate total condensation reactor, and the overall height of the civil engineering frame is approximately 35m.

[0023] Furthermore, the system also includes a CO2 compressor, with 15% to 25% of the total volume of compressed CO2 gas fed into the urea synthesis tower and 75% to 85% fed into the high-pressure stripping tower.

[0024] Furthermore, the operating parameters of the urea synthesis tower are: pressure 13.5~15.0MPa, temperature 180~186℃, NH3 / CO2 volume ratio 3.0~3.6, and H2O / CO2 volume ratio 0.40~0.7.

[0025] The dedicated horizontal high-pressure ammonium carbamate total condensation reactor of the present invention has the following advantages:

[0026] 1. Compared with traditional falling film high-pressure condensers, the horizontal high-pressure ammonium carbamate total condensation reactor of the present invention has the tube-side material running horizontally in the condenser, resulting in good gas-liquid two-phase mixing, a large heat transfer coefficient, a long residence time, and a high temperature of about 180°C. Therefore, it has a large heat transfer temperature difference and heat transfer coefficient, which allows the designed heat exchange area to be reduced by more than 50%, greatly reducing investment and producing low-pressure steam with higher pressure as a byproduct.

[0027] 2. By adding a reaction section and extending the residence time of materials in the equipment, the process materials can be fully condensed, absorbed and reacted in this invention to generate ammonium carbamate and a certain amount of urea. This can divert the load of the urea synthesis tower and effectively solve the problem of the urea synthesis tower in large urea plants being restricted in diameter and height due to manufacturing and transportation reasons.

[0028] 3. This structural design can increase the pressure of the by-product steam, reaching up to 0.5 MPa(G). The increased steam grade facilitates its efficient utilization. Furthermore, the steam condensate side (i.e., the shell side) features natural circulation, eliminating the need for a circulation pump, thus saving investment and reducing power consumption.

[0029] 4. The horizontal high-pressure ammonium carbamate total condensation reactor has a high-pressure condenser tube side, typically 13.5–17 MPa(G), and a low-pressure shell side, typically 0.4–0.9 MPa(G). Therefore, the equipment structure is simple, requiring no special internal welding technology, resulting in lower manufacturing requirements, lower technical risks, and lower manufacturing costs. Domestic technology is fully capable of producing it. The highly corrosive process material flows through the tube side, while the steam condensate flows through the shell side. Therefore, the shell side material can be made of a non-corrosive material. Simultaneously, the highly corrosive process material has a long residence time inside the tubes, forming a urea solution, which reduces the length of the horizontal plug flow synthesis section with trays, thus lowering the overall equipment cost.

[0030] 5. The shell side of the condenser in the horizontal high-pressure ammonium carbamate total condensation reactor is a kettle-type reboiler, which is used to produce low-pressure steam as a by-product. There is no need to set up a separate vapor-liquid separator, which simplifies the equipment layout and saves equipment investment.

[0031] The CO2 stripping urea production system of the present invention has the following advantages:

[0032] 1. By improving the existing urea production process, the urea synthesis conversion rate can be effectively increased, raising the CO2 conversion rate from about 58% in the traditional CO2 stripping method to 62%~64%. At the same time, it can produce low-pressure steam with higher pressure by-products, raising the pressure of the low-pressure steam by-products from about 0.35MPa(G) in the traditional CO2 stripping method to about 0.55MPaG.

[0033] 2. While improving the effective conversion rate of urea, the urea synthesis tower and horizontal high-pressure ammonium carbamate total condensation reactor can be arranged on or near the ground. The overall height of the civil engineering frame of the urea plant is about 35m, which is 30-35m lower than the traditional urea civil engineering frame. The process modification is simple, saves investment, is convenient to operate, and is easy to maintain and repair. Attached Figure Description

[0034] Figure 1 This is a process flow diagram of the CO2 stripping urea production system in the example.

[0035] Figure 2 This is a schematic diagram of the structure of the horizontal high-pressure ammonium carbamate total condensation reactor in the embodiment.

[0036] Figure label: Figure 1 In the middle, 21-horizontal high-pressure ammonium carbamate total condensation reactor, 31-urea synthesis tower, 41-high-pressure stripping tower, 51-high-pressure scrubber, in Figure 2 In the diagram, 1- has a U-shaped tube bundle reboiler; 2- has a U-shaped tube bundle reboiler shell; 3- has a U-shaped tube bundle reboiler tubes; 4- has a U-shaped tube bundle reboiler process gas inlet; 5- has a redistribution chamber; 6- has a redistribution element in the redistribution chamber; 7- has a U-shaped tube bundle reboiler steam outlet; 8- has a U-shaped tube bundle reboiler steam condensate inlet; 9- has a U-shaped tube bundle reboiler exhaust outlet. 10 - Horizontal plug flow synthesis section with trays; 11 - Gas inlet of horizontal plug flow synthesis section with trays; 12 - Gas distributor at the inlet of horizontal plug flow synthesis section with trays; 13 - Guide tray of horizontal plug flow synthesis section with trays; 14 - Liquid outlet of horizontal plug flow synthesis section with trays; 15 - Gas outlet of horizontal plug flow synthesis section with trays; 16 - Inlet of ammonium carbamate liquid with U-shaped tube bundle reboiler.

[0037] Figure 3 This is a schematic diagram of the redistribution element in the redistribution chamber of the horizontal high-pressure ammonium carbamate total condensation reactor of the embodiment. It is a one-hole plate-shaped distribution element.

[0038] Figure 4 This is a schematic diagram of the structure of the inlet gas distributor of the synthesis section of the horizontal high-pressure ammonium carbamate total condensation reactor redistribution chamber, which is a long tubular axially perforated distributor. Detailed Implementation

[0039] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0040] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product or device.

[0041] The air stripping urea production process of the present invention includes the following steps:

[0042] (1) The raw material CO2 gas is sent into the high-pressure stripping tower, and the ammonium carbamate from the urea synthesis tower is decomposed into NH3 and CO2 gas under steam heating and then sent into the horizontal high-pressure ammonium carbamate total condensation reactor.

[0043] (2) The ammonium carbamate solution from the downstream system is sent to a high-pressure scrubber to condense and absorb NH3 and CO2 gases. The ammonium carbamate solution generated by the reaction flows into the horizontal high-pressure ammonium carbamate total condensation reactor by means of the potential difference. The unreacted tail gas is discharged (when the inert gas content in the raw material CO2 gas is low, the high-pressure scrubber is cancelled and the ammonium carbamate solution is directly sent to the U-tube heat exchanger of the horizontal high-pressure ammonium carbamate total condensation reactor).

[0044] (3) The ammonium carbamate solution from the high-pressure scrubber and the NH3 and CO2 gas from the high-pressure stripping tower are condensed, absorbed and reacted in the horizontal high-pressure ammonium carbamate total condensation reactor. The generated ammonium carbamate and urea are pressurized by the high-pressure injector and then enter the urea synthesis tower for further reaction. The unreacted NH3 and CO2 gas are sent to the high-pressure scrubber (if the inert gas content in the raw material CO2 gas is low, the high-pressure scrubber is cancelled and the unreacted NH3 and CO2 gas are sent directly to the downstream process after depressurization).

[0045] (4) The raw material CO2 gas is sent into the urea synthesis tower, where it reacts further with ammonium carbamate and urea from the horizontal high-pressure ammonium carbamate total condensation reactor. The resulting reaction liquid composed of ammonium carbamate and urea flows into the high-pressure stripping tower by pressure difference and then enters the next process. The unreacted NH3 and CO2 gas are sent into the horizontal high-pressure ammonium carbamate total condensation reactor.

[0046] The raw material CO2 comes from a CO2 compressor, with 15-25% of its total volume fed into the urea synthesis tower and 75-85% fed into the high-pressure stripping tower.

[0047] The high-pressure ejector uses liquid ammonia as the driving medium.

[0048] The high-pressure gas lift tower is a falling film heater.

[0049] The operating parameters of the urea synthesis tower are: 13.5-15.0 MPa(G), 180-186℃, NH3 / CO2=3.0-3.6, H2O / CO2=0.40-0.70.

[0050] This invention's production process alters the flow direction of unreacted gases (NH3 and CO2) at the outlet of the horizontal high-pressure ammonium carbamate total condensation reactor. Instead of passing through the urea synthesis tower, the gases go directly to the high-pressure scrubber, reducing the pressure difference between the reactor and the scrubber. This allows the ammonium carbamate liquid to flow into the reactor using its potential difference, eliminating the need for pressurized transport and preventing excessive ammonia from entering the reactor. Consequently, the internal medium exhibits a low ammonia-to-carbon ratio and a high water-to-carbon ratio, facilitating condensation at higher temperatures and producing higher-pressure low-pressure steam as a byproduct. Simultaneously, the horizontal high-pressure ammonium carbamate... The reacted liquid (i.e., the generated ammonia carbamate and urea) from the ammonium total condensation reactor is pressurized by a high-pressure injector driven by the raw material liquid ammonia and then sent to the urea synthesis tower for further reaction. Because all the liquid ammonia enters the synthesis tower, the medium inside the tower has a high ammonia-to-carbon ratio and a low water-to-carbon ratio, which is beneficial for improving the synthesis conversion rate. The reaction liquid exiting the urea synthesis tower flows into a high-pressure stripping tower using pressure differential. Through the above changes in the production process, the urea synthesis tower and the horizontal high-pressure ammonium carbamate total condensation reactor can be arranged at or near the ground, reducing the height by 30-35m compared to traditional urea frame structures. The raw material liquid ammonia also participates in the reaction to produce urea after entering the synthesis tower. Unreacted gas from the urea synthesis tower is sent to the plug flow reaction section of the horizontal high-pressure ammonium carbamate total condensation reactor to provide heat for urea production in this section.

[0051] Furthermore, in order to maintain the thermal balance of the urea synthesis tower and to maintain the low ammonia-to-carbon ratio of the horizontal high-pressure ammonium carbamate total condensation reactor, about 15-25% (volume percentage) of the raw material CO2 from the CO2 compressor is directly fed into the urea synthesis tower, while the rest is sent to the high-pressure stripping tower.

[0052] Because the gas and liquid at the outlet of the horizontal high-pressure ammonium carbamate total condensation reactor are separated, the gas flow direction at the outlet changes. This requires that ammonia and carbon dioxide be condensed and absorbed within the horizontal high-pressure ammonium carbamate total condensation reactor as much as possible. However, in traditional membrane-type high-pressure condensers, the gas and liquid flow from top to bottom, making it difficult to completely separate the gas and liquid at the outlet. In addition, traditional membrane-type high-pressure condensers do not have a reaction zone, and the condensation and absorption rate of NH3 and CO2 gases within the high-pressure condenser is not high. Therefore, it is necessary to design a special device that can condense and absorb ammonia and carbon dioxide within the horizontal high-pressure ammonium carbamate total condensation reactor as much as possible, and can both generate ammonium carbamate and convert it into urea.

[0053] The horizontal high-pressure ammonium carbamate total condensation reactor includes a condenser equipped with U-shaped heat exchange tubes. The condenser is a kettle-type reboiler with a gas inlet, an ammonium carbamate liquid inlet, and a steam outlet at the top, and a steam-condensate inlet at the bottom. The gas inlet and ammonium carbamate liquid inlet are connected to the tube side of the condenser, while the steam-condensate inlet and steam outlet are connected to the shell side of the condenser. A horizontal reactor connected to the condenser is also located at the tube-side outlet of the condenser. The reactor has a gas inlet at the bottom connected to an internal gas distributor, a gas outlet at the far top, and a liquid outlet at the far bottom of the reactor.

[0054] The reactor is also equipped with at least one baffle plate to improve the reaction conversion rate.

[0055] The gas and liquid inlets are also connected to the condenser tube side via gas and liquid distributors. This invention is a horizontal device, with the reactor and condenser connected via heat exchange tubes. Process materials flow horizontally along the tube side (i.e., heat exchange tubes) in the condenser, while steam and condensate flow along the shell side. Due to horizontal turbulence, the materials are uniformly mixed within the heat exchange tubes. The reactor is mostly filled with liquid, and the gas and liquid phases enter from the top of the condenser. This horizontal turbulence significantly increases the residence time and heat transfer coefficient of the process materials in the heat exchange tubes, and allows for sufficient condensation and absorption of the liquid upon reaching the reactor. Finally, the gas exits through the gas outlet at the top of the reactor and enters the high-pressure scrubber, while the urea and ammonium carbamate produced by the reaction exit through the reaction liquid outlet for the next process. To ensure sufficient gas-liquid contact, baffles are installed inside the reactor; these baffles can be non-perforated, perforated, or other types. A gas and liquid distributor is also installed in the condenser inlet to ensure uniform distribution of gas and liquid into the heat exchange tubes.

[0056] Example

[0057] Reference Figure 1In the high-pressure process, CO2 gas compressed by the CO2 compressor at 14.5 MPa (G) and 120°C is divided into two parts and enters the high-pressure system. 75-85% of the CO2 gas enters the tube side of the high-pressure stripping tower 41 from the bottom, and 15-25% of the CO2 gas enters the urea synthesis tower 31 from the bottom to maintain its thermal balance. The high-pressure stripping tower 41 is a falling film heater, and the shell side is heated by steam above 1.4 MPa (G) to provide the heat required for the decomposition of ammonium carbamate from the urea synthesis tower 31. The stripped gas (i.e., NH3 and CO2 gas) generated by the reaction enters the horizontal high-pressure system from the top outlet on the tube side of the high-pressure stripping tower 41. The ammonium methyl ether total condensation reactor 21 is located at the upper tube side. Meanwhile, the ammonium methyl ether liquid from the downstream system enters the high-pressure scrubber 51, where it contacts and condenses with NH3 and CO2 gases from the horizontal high-pressure ammonium methyl ether total condensation reactor 21. The high-pressure scrubber 51 has a packing section at the top and a heat exchange section at the bottom, cooled by hot water. The hot water removes the heat of generation and condensation of the ammonium methyl ether liquid within the high-pressure scrubber 51 in a closed-loop system. Uncondensed gas enters the upper packing section and is washed by the ammonium methyl ether liquid from the circulating process to recover NH3 and CO2. The resulting ammonium methyl ether liquid overflows from the high-pressure scrubber 51 and enters the upper tube side of the horizontal high-pressure ammonium methyl ether total condensation reactor 21. The gas exiting the high-pressure scrubber 51 contains small amounts of ammonia and carbon dioxide and is sent to a low-pressure absorption tower. After absorption by process condensate and steam condensate, the absorbed tail gas is discharged into the atmosphere or sent to a subsequent tail gas treatment system.

[0058] The stripped gas from the high-pressure stripping tower 41 and the ammonium carbamate solution from the high-pressure scrubber 51 enter the horizontal high-pressure ammonium carbamate total condensation reactor 21 from the top. Here, CO2 and NH3 are condensed and absorbed to generate ammonium carbamate and urea. After being pressurized by the high-pressure ejector 61 driven by the raw material liquid ammonia, it enters the urea synthesis tower 31. Unreacted CO2 and NH3 gases are sent to the high-pressure scrubber 51 from the top. The raw material liquid ammonia, as the driving fluid of the high-pressure ejector 61, pressurizes the ammonium carbamate and urea solution from the horizontal high-pressure ammonium carbamate total condensation reactor 21 and sends it to the urea synthesis tower 31. There, it reacts with the CO2 gas from the CO2 compressor in the urea synthesis tower 31 to generate a reaction liquid composed of ammonium carbamate and urea. The reaction liquid flows by gravity into the pipe side of the high-pressure stripping tower 41 using the pressure difference, and then enters the medium and low pressure decomposition system at the bottom of the high-pressure stripping tower 41 for the next process. Unreacted CO2 and NH3 gases from urea synthesis tower 31 are fed from the top into a horizontal high-pressure ammonium carbamate total condenser reactor 21. The urea synthesis tower 31 is equipped with multiple high-efficiency trays to ensure thorough mixing and contact between the gas and liquid materials, preventing backmixing and improving conversion rate. The reaction conditions in urea synthesis tower 31 are: 13.5-15.0 MPa(G), 180-186℃, NH3 / CO2 = 3.0-3.6, H2O / CO2 = 0.40-0.7, and CO2 conversion rate approximately 62-64%.

[0059] The urea synthesis tower 31 is located on the ground. The bottom of the horizontal high-pressure ammonium carbamate total condensation reactor 21 and the high-pressure stripping tower 41 are located at a height close to the ground (within 2m of vertical height from the ground). The bottom of the high-pressure scrubber 51 is at least 10m above the top of the horizontal high-pressure ammonium carbamate total condensation reactor 21. The overall height of the civil engineering frame is about 35m.

[0060] The horizontal high-pressure ammonium carbamate total condensation reactor 21 is a horizontal device, including a kettle reboiler 1 equipped with multiple U-shaped heat exchange tubes 3 and a plug flow reaction section 10 connected thereto. The kettle reboiler 1 is provided with a gas inlet 4 and an ammonium carbamate liquid inlet 16 connected to the heat exchange tubes 3 (i.e., the tube side) and a steam condensate inlet 8 connected to the shell side. The gas inlet 4 and the ammonium carbamate liquid inlet 16 are connected to the heat exchange tubes 3 through the redistribution element 6 in the redistribution chamber 5. The upper part of the reboiler is provided with a steam outlet 7 that communicates with the shell side; the plug flow synthesis section 10 is connected to the tube side of the reboiler 1, and the plug flow synthesis section 10 is provided with multiple guide trays 13. The top of the trays has small holes to prevent liquid accumulation or gas collection. The top of the trays is provided with a gas outlet 15, and the bottom of the trays is provided with a reaction liquid outlet 14; the bottom of the plug flow synthesis section 10 is provided with an air inlet 11 that is connected to the gas phase of the urea synthesis tower. The air inlet is connected to the gas distributor inside the plug flow synthesis section 10.

[0061] Working principle of horizontal high-pressure ammonium carbamate total condensation reactor 21:

[0062] The stripped gas (CO2, NH3) from the high-pressure stripping tower and the ammonium carbamate solution from the high-pressure scrubber enter the reboiler tube bundle 3 through the upper gas inlet 4 and ammonium carbamate solution inlet 16, respectively. After passing through the gas and liquid distributor 6, they flow turbulently along the tube side into the plug flow reactor section 10, and continue to pass horizontally through the guide tray 13 within the plug flow reactor section 10. The stripped gas (CO2, NH3) and ammonium carbamate solution fully contact and absorb each other within the tubes, and further condense and absorb within the plug flow reactor section 10 to generate ammonium carbamate and urea. The unreacted gas (CO2, NH3) from the urea synthesis tower 31 enters the plug flow reactor section 10 of the horizontal high-pressure ammonium carbamate total condensation reactor 21 to provide heat for urea production. The gas after reaction in the plug flow reactor section 10 is discharged from the top gas outlet 15, while the ammonium carbamate and urea are discharged from the reaction liquid outlet 14. The steam condensate enters the shell 2 of the reboiler through the steam condensate inlet 8, and the generated steam is discharged through the steam outlet 7 to absorb the reaction heat (temperature approximately 180°C) of the material in the tube bundle 3 of the reboiler, producing 0.5-0.55 MPa(G) steam as a byproduct. The tube side is under high pressure, with a pressure of 13.5-17 MPa(G), while the shell side is under low pressure, with a pressure of 0.4-0.9 MPa(G).

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A horizontal high-pressure ammonium carbamate total condensation reactor, characterized in that... include: The horizontally arranged condensation section and plug flow reaction section; The condensation section is a kettle-type reboiler with a horizontally placed U-shaped heat exchange tube bundle on the shell side; the plug flow reaction section is connected to the outlet of the U-shaped heat exchange tube bundle, and several vertically arranged guide trays are installed in the plug flow reaction section. The reactants enter the U-shaped heat exchange tube bundle in the condensation section, where they exchange heat with the steam condensate in the shell side and achieve uniform mixing of the reactants before entering the plug flow reaction section for reaction.

2. The horizontal high-pressure ammonium carbamate total condensation reactor according to claim 1, characterized in that: The upper part of the condensation section is provided with a reactant inlet that communicates with the inlet of the U-shaped heat exchange tube bundle, while the steam condensate inlet and outlet that communicate with the shell side are respectively provided in the lower and upper parts of the condensation section.

3. The horizontal high-pressure ammonium carbamate total condensation reactor according to claim 2, characterized in that: A redistribution chamber is provided at the inlet of the U-shaped heat exchange tube bundle, and a redistribution element for optimizing fluid distribution is provided in the redistribution chamber.

4. The horizontal high-pressure ammonium carbamate total condensation reactor according to claim 1, characterized in that: An air inlet is provided at the bottom of the connection between the plug flow reaction section and the condensation section, and the air inlet is connected to a tubular gas distributor installed inside the plug flow reaction section.

5. The horizontal high-pressure ammonium carbamate total condensation reactor according to claim 1, characterized in that: The end of the push-flow reaction section is provided with a gas-liquid separation chamber to separate the reaction products into gas and liquid. A gas outlet is provided at the upper part of the end and a reaction liquid outlet is provided at the lower part. The separated gas and liquid are discharged from the gas outlet and the reaction liquid outlet, respectively.

6. A CO2 stripping urea production system, characterized in that... include: The horizontal high-pressure ammonium carbamate total condensation reactor, urea synthesis tower, and high-pressure stripping tower as described in any one of claims 1 to 5; The reaction liquid outlet of the horizontal high-pressure ammonium carbamate total condensation reactor is directly or through a high-pressure ejector connected to the reaction liquid inlet at the bottom of the urea synthesis tower. When passing through the high-pressure ejector, the raw material liquid ammonia is used as the driving medium, and the temperature of the liquid ammonia is 40-140℃. The reaction products of the horizontal high-pressure ammonium carbamate total condensation reactor, ammonium carbamate and urea, react with the raw material liquid ammonia and compressed CO2 gas from the bottom into the urea synthesis tower. The reactant liquid outlet of the urea synthesis tower is connected to the pipe-side inlet of the high-pressure stripping tower, and the reactant gas outlet at the top of the urea synthesis tower is connected to the gas inlet of the horizontal high-pressure ammonium carbamate total condensation reactor. Unreacted CO2 and NH3 gases enter the horizontal high-pressure ammonium carbamate total condensation reactor through the gas outlet. The stripping gas from the high-pressure stripping tower, together with the added ammonium carbamate solution, enters from the reactant inlet of the horizontal high-pressure ammonium carbamate total condensation reactor. CO2 and NH3 are condensed and absorbed, and the reaction produces ammonium carbamate and urea. The reaction liquid in the urea synthesis tower enters from the top of the high-pressure stripping tower, while the compressed CO2 gas from the raw material enters from the bottom of the high-pressure stripping tower. The ammonium carbamate in the reaction liquid is decomposed into NH3 and CO2 gas and sent to the U-shaped heat exchange tube bundle section of the horizontal high-pressure ammonium carbamate total condensation reactor. Urea is discharged from the bottom of the high-pressure stripping tower.

7. The CO2 stripping urea production system according to claim 6, characterized in that: The system also includes a high-pressure scrubber. Unreacted CO2 and NH3 gases from the horizontal high-pressure ammonium carbamate total condensation reactor enter through the top inlet of the high-pressure scrubber and are washed and recovered with the added ammonium carbamate solution. The generated ammonium carbamate solution overflows from the high-pressure scrubber into the horizontal high-pressure ammonium carbamate total condensation reactor.

8. The CO2 stripping urea production system according to claim 7, characterized in that: The urea synthesis tower is located on the ground, the bottom of the high-pressure stripping tower is located within 2m of the ground, the bottom of the high-pressure scrubber is at least 10m above the top of the horizontal high-pressure ammonium carbamate total condensation reactor, and the overall height of the civil engineering frame is approximately 35m.

9. The CO2 stripping urea production system according to claim 6, characterized in that: The system also includes a CO2 compressor, and 15% to 25% of the total volume of the compressed CO2 gas is fed into the urea synthesis tower, while 75% to 85% is fed into the high-pressure stripping tower.

10. The CO2 stripping urea production system according to claim 6, characterized in that: The operating parameters of the urea synthesis tower are: pressure 13.5-15.0 MPa, temperature 180-186℃, NH3 / CO2 volume ratio 3.0-3.6, and H2O / CO2 volume ratio 0.40-0.7.

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