Urea hydrolysis product gas treatment system

Abstract

The utility model discloses a urea hydrolysis product gas treatment system, which belongs to the technical field of flue gas denitration reducing agent preparation, and comprises a first water vapor adsorption device, a second water vapor adsorption device and a third water vapor adsorption device, two ends of the first product gas branch pipeline are respectively connected with the first water vapor adsorption device and the product gas pipeline; two ends of the first dry product gas output pipeline are respectively connected with the first water vapor adsorption device and the metering distribution module; a second molecular sieve assembly is arranged in the second water vapor adsorption device; two ends of the second product gas branch pipeline are respectively connected with the second water vapor adsorption device and the product gas pipeline; two ends of the second dry product gas output pipeline are respectively connected with the second water vapor adsorption device and the first dry product gas output pipeline; according to the system provided by the invention, the temperature of the product gas can be always kept above the dew point temperature in the conveying process, so that the situation that the pipeline is blocked by ammonium carbamate crystals generated in the pipeline due to water vapor recondensation is avoided.

Description

Technical Field

[0001] This utility model relates to the field of flue gas denitrification reducing agent preparation technology, and more specifically, to a urea hydrolysis product gas treatment system. Background Technology

[0002] Currently, urea hydrolysis has become the main method for producing ammonia, a selective SCR denitrification reducing agent, in thermal power plants. The urea hydrolysis process involves transporting a urea solution with a concentration of approximately 50% from a storage tank to the hydrolysis reactor. Saturated steam then enters the hydrolysis reactor through a coil to heat and maintain the temperature and pressure conditions within the reactor, causing the urea to hydrolyze and generate a mixed gas containing ammonia (NH3), carbon dioxide (CO2), and water (H2O). This mixed gas exits from the outlet of the hydrolysis reactor and is transported along a product gas pipeline to an ammonia metering and distribution module. There, it is mixed with hot diluted air in an ammonia-air mixer to adjust the ammonia concentration to approximately 5%. Subsequently, the diluted ammonia enters the flue gas mixing system to participate in the denitrification reaction, thereby effectively reducing the emission concentration of nitrogen oxides in the flue gas and ensuring that the flue gas meets environmental standards.

[0003] The generated mixed gas contains the largest proportion of water vapor, approximately 43.8%. If the product gas pipeline is long, the temperature along the pipeline can drop significantly, resulting in insufficient heating effect. This is especially true during winter when the boiler is operating at low load. Due to the low temperature of the heating steam, it is difficult to maintain the temperature of the mixed gas above the dew point, causing the water vapor in the product gas to condense and react with ammonia and carbon dioxide to form amino carbamate crystals, which can clog the pipeline. This situation not only exacerbates the corrosion of pipelines and valves but can also seriously affect the stable operation of the denitrification system. Utility Model Content

[0004] The purpose of this invention is to solve the technical problem that the product gas produced by urea hydrolysis is prone to water vapor condensation during transportation, which ultimately affects the safe and stable operation of the denitrification system. Therefore, a urea hydrolysis product gas treatment system is proposed.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A urea hydrolysis product gas treatment system, wherein the urea hydrolysis product gas treatment system is connected to a product gas pipeline between a hydrolysis reactor and a metering and distribution module, characterized in that the urea hydrolysis product gas treatment system comprises:

[0007] The first water vapor adsorption device is a tubular structure with a first air inlet and a first air outlet at its two ends. The first water vapor adsorption device is equipped with a first molecular sieve component for adsorbing product gas water vapor.

[0008] The first product gas branch pipeline has one end connected to the first air inlet and the other end connected to the product gas pipeline, which is used to transport the product gas in the product gas pipeline to the first water vapor adsorption device.

[0009] The first drying product gas output pipeline has one end connected to the first gas outlet and the other end connected to the metering and distribution module.

[0010] The second water vapor adsorption device is a tubular structure with a second air inlet and a second air outlet at its two ends. The second water vapor adsorption device is equipped with a second molecular sieve component for adsorbing product gas and water vapor.

[0011] The second product gas branch pipeline has one end connected to the second air inlet and the other end connected to the product gas pipeline.

[0012] The second dry product gas output pipe has one end connected to the second gas outlet and the other end connected to the first dry product gas output pipe, so that the product gas flows into the first dry product gas output pipe and is transported to the metering and distribution module through the first dry product gas output pipe.

[0013] Furthermore, the urea hydrolysis product gas treatment system also includes a hot air supply mechanism for drying the first molecular sieve assembly and the second molecular sieve assembly; the hot air supply mechanism includes:

[0014] Air preheater;

[0015] A steam delivery pipeline, which is connected to the air preheater, is used to deliver steam to the air preheater;

[0016] A cold air delivery pipeline, which is connected to the air preheater, is used to deliver cold air to the air preheater for heat exchange with steam.

[0017] A condensate recovery pipe is connected to the air preheater and is used to discharge the condensate generated after steam heat exchange away from the air preheater.

[0018] The first hot air delivery pipe has its two ends connected to the first air inlet and the air preheater, respectively, and is used to deliver hot air to the first water vapor adsorption device.

[0019] The second hot air delivery pipe, with its two ends connected to the second air inlet and the air preheater respectively, is used to deliver hot air to the second water vapor adsorption device.

[0020] Furthermore, the hot air supply mechanism also includes:

[0021] A desuperheating and pressure reducing device, which is connected to the steam conveying pipeline;

[0022] A hot air blower, which is connected to the cold air delivery duct.

[0023] Furthermore, the urea hydrolysis product gas treatment system also includes a molecular sieve regeneration control mechanism; the molecular sieve regeneration control mechanism includes:

[0024] The first pressure sensor is connected to the first dry product gas output pipe and is used to detect the product gas pressure difference at the pipe opening of the first dry product gas output pipe and output an electrical signal.

[0025] The second pressure sensor is connected to the second dry product gas output pipe and is used to detect the product gas pressure difference at the pipe opening of the second dry product gas output pipe and output an electrical signal.

[0026] The first product gas input valve is connected to the first product gas branch pipeline and is used to control the on / off state of the first product gas branch pipeline.

[0027] The second product gas inlet valve is connected to the second product gas branch pipeline and is used to control the on / off state of the second product gas branch pipeline.

[0028] A first hot air regulating valve is connected to the first hot air delivery pipeline and is used to control the on / off state of the first hot air delivery pipeline.

[0029] The second hot air regulating valve is connected to the second hot air delivery pipeline and is used to control the on / off state of the second hot air delivery pipeline.

[0030] The product gas input valve control module is communicatively connected to the first pressure sensor, the second pressure sensor, the first product gas input valve, and the second product gas input valve. The product gas input valve control module controls and changes the opening and closing states of the first product gas input valve and the second product gas input valve according to the electrical signals output by the first pressure sensor and the second pressure sensor.

[0031] A molecular sieve regeneration control module is communicatively connected to the first pressure sensor, the second pressure sensor, the first hot air regulating valve, and the second hot air regulating valve, respectively. The molecular sieve regeneration control module controls the opening and closing states of the first hot air regulating valve and the second hot air regulating valve according to the electrical signals output by the first pressure sensor and the second pressure sensor.

[0032] Furthermore, the first molecular sieve assembly is located between the first inlet end and the first outlet end, and the first molecular sieve assembly includes:

[0033] A primary molecular sieve is located on the side of the first water vapor adsorption device near the first air inlet, and is used to adsorb water vapor in the product gas and maintain the product gas flow rate.

[0034] A secondary molecular sieve is located in the middle section of the first water vapor adsorption device;

[0035] The three-stage molecular sieve is located on the side of the first water vapor adsorption device near the first gas outlet, and is used to adsorb the remaining water vapor in the product gas.

[0036] Furthermore, the adsorbent packing density of the primary molecular sieve is 0.60 kg / L to 0.65 kg / L; the adsorbent packing density of the secondary molecular sieve is 0.65 kg / L to 0.70 kg / L; and the adsorbent packing density of the tertiary molecular sieve is 0.70 kg / L to 0.75 kg / L.

[0037] Furthermore, a first flow indicator is connected to the side of the first product gas branch pipe near the first air inlet; a second flow indicator is connected to the side of the second product gas branch pipe near the second air inlet.

[0038] The beneficial effects of this utility model are as follows: The urea hydrolysis product gas treatment system provided in this application reduces the water vapor content in the product gas through the design of a first water vapor adsorption device and a second water vapor adsorption device. This effectively solves the technical problem of pipe blockage caused by the formation of ammonium carbamate crystals in the pipe after water vapor condensation, and reduces equipment corrosion. Furthermore, by adopting a molecular sieve regeneration control mechanism, the first water vapor adsorption device and the second water vapor adsorption device are alternately switched to perform water vapor adsorption work on the product gas. The first molecular sieve component and the second molecular sieve component are regenerated alternately, so that at least one of the first water vapor adsorption device and the second water vapor adsorption device is in an unsaturated working condition, thereby achieving the technical effect of continuous operation of the urea hydrolysis product gas treatment system. Attached Figure Description

[0039] Figure 1This is an overall schematic diagram of a urea hydrolysis product gas treatment system provided in an embodiment of this utility model;

[0040] The markings in the diagram are as follows:

[0041] 11. First water vapor adsorption device; 111. First air inlet; 112. First air outlet; 113. First molecular sieve assembly; 1131. Primary molecular sieve; 1132. Secondary molecular sieve; 1133. Tertiary molecular sieve; 12. First product gas branch pipeline; 121. First flow indicator; 13. First dried product gas output pipeline;

[0042] 21. Second water vapor adsorption device; 211. Second air inlet; 212. Second air outlet; 213. Second molecular sieve assembly; 22. Second product gas branch pipeline; 221. Second flow indicator; 23. Second dried product gas output pipeline;

[0043] 3. Hot air supply mechanism;

[0044] 31. Air preheater; 32. Steam conveying pipeline; 33. Cold air conveying pipeline; 34. Drainage recovery pipeline; 35. Desuperheater and pressure reducer; 36. Hot air blower; 37. First hot air conveying pipeline; 38. Second hot air conveying pipeline;

[0045] 41. First pressure sensor; 42. Second pressure sensor; 43. First product gas input valve; 44. Second product gas input valve; 45. First hot air regulating valve; 46. Second hot air regulating valve; 47. Product gas input valve control module; 48. Molecular sieve regeneration control module;

[0046] 5. Hydrolysis reactor; 6. Product gas pipeline; 7. Metering and distribution module. Detailed Implementation

[0047] 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 protection scope of the present utility model.

[0048] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0049] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0050] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0051] See also Figure 1 The embodiment of this application shown provides a urea hydrolysis product gas treatment system. In practical applications, the urea hydrolysis product gas treatment system is installed on the product gas pipeline 6 between the hydrolysis reactor 5 and the metering and distribution module 7, and is located at one end of the product gas pipeline 6 near the hydrolysis reactor 5. It is used to dry the mixed gas output from the hydrolysis reactor 5, i.e., the product gas, to reduce the water vapor content in the product gas and avoid the phenomenon of water vapor condensation when the product gas is significantly cooled or insufficiently heated along the pipeline.

[0052] The urea hydrolysis product gas treatment system provided in this application includes: a first water vapor adsorption device 11, a first product gas branch pipeline 12, a first dry product gas output pipeline 13, a second water vapor adsorption device 21, a second product gas branch pipeline 22, and a second dry product gas output pipeline 23.

[0053] Both the first water vapor adsorption device 11 and the second water vapor adsorption device 21 are tubular structures. The first water vapor adsorption device 11 has a first air inlet 111 and a first air outlet 112 at its two ends. The first water vapor adsorption device 11 has a first molecular sieve assembly 113 inside. The first molecular sieve assembly 113 is located between the first air inlet 111 and the first air outlet 112. As the product gas entering the first water vapor adsorption device 11 moves from the first air inlet 111 to the first air outlet 112, it reduces its water vapor content through the first molecular sieve assembly 113.

[0054] One end of the first product gas branch pipeline 12 is connected to the first air inlet 111, and the other end is connected to the product gas pipeline 6. The product gas output from the hydrolysis reactor 5 is transported to the first water vapor adsorption device 11 via the product gas pipeline 6 and the first product gas branch pipeline 12 to reduce the water vapor content.

[0055] One end of the first dry product gas output pipe 13 is connected to the first gas outlet 112, and the other end is connected to the metering and distribution module 7. The dry product gas obtained after water vapor adsorption in the first water vapor adsorption device 11 by the first molecular sieve component 113 is transported to the metering and distribution module 7 through the first dry product gas output pipe 13. The dry product gas is then mixed with hot diluted air in the ammonia-air mixer through the metering and distribution module 7. After adjusting the ammonia concentration to 5%, it participates in the subsequent denitrification reaction.

[0056] As one embodiment of this application, the second water vapor adsorption device 21 can be used to simultaneously adsorb water vapor from product gas with the first water vapor adsorption device 11, thereby increasing the flow rate of product gas that the urea hydrolysis product gas treatment system can process simultaneously. According to the above technical solution, it can be understood that the second water vapor adsorption device 21 has a second inlet end 211 and a second outlet end 212 at its two ends respectively. The second water vapor adsorption device 21 has a second molecular sieve component 213 inside, which is located between the second inlet end 211 and the second outlet end 212. As the product gas entering the second water vapor adsorption device 21 moves from the second inlet end 211 to the second outlet end 212, its water vapor content is reduced by the second molecular sieve component 213.

[0057] One end of the second product gas branch pipeline 22 is connected to the second air inlet 211, and the other end is connected to the product gas pipeline 6; the product gas output from the hydrolysis reactor 5 can be transported to the second water vapor adsorption device 21 through the product gas pipeline 6 and the second product gas branch pipeline 22 to reduce the water vapor content.

[0058] One end of the second dry product gas output pipe 23 is connected to the second gas outlet 212, and the other end is connected to the first dry product gas output pipe 13, so that the dry product gas obtained after water vapor adsorption by the second molecular sieve component 213 flows into the first dry product gas output pipe 13 and is transported to the metering and distribution module 7 through the first dry product gas output pipe 13.

[0059] The urea hydrolysis product gas treatment system provided in this application, through the design of a first water vapor adsorption device 11 and a second water vapor adsorption device 21, can effectively reduce the water vapor content in the product gas, avoid water vapor condensation during the process of the product gas being transported to the metering and distribution module 7, and eliminate the risk of pipeline blockage.

[0060] In the above technical solution, the first molecular sieve component 113 and the second molecular sieve component 213 will reach saturation after adsorbing water vapor for a long time. Under saturation, the water vapor adsorption capacity of the first molecular sieve component 113 and the second molecular sieve component 213 will decrease significantly or even be lost, making it impossible to guarantee the product gas during subsequent transportation. In order to solve the above technical problem, the technical solution of this application adopts hot air drying to regenerate the first water vapor adsorption device 11 and the second water vapor adsorption device 21 under saturation and restore their water vapor adsorption capacity. The urea hydrolysis product gas treatment system also includes a hot air supply mechanism 3. The hot air supply mechanism 3 includes: an air preheater 31, a steam conveying pipeline 32, a cold air conveying pipeline 33, a hydrophobic recovery pipeline 34, a desuperheater and pressure reducer 35, a hot air blower 36, a first hot air conveying pipeline 37, and a second hot air conveying pipeline 38.

[0061] The air preheater 31 is connected to the steam conveying pipe 32, the cold air conveying pipe 33, and the condensate recovery pipe 34. High-temperature and high-pressure steam supplied by external equipment is conveyed to the air preheater 31 through the steam conveying pipe 32. External air is conveyed to the air preheater 31 through the cold air conveying pipe 33. After exchanging heat with the high-temperature and high-pressure steam in the air preheater 31, hot air is formed to purge the first molecular sieve assembly 113 and the second molecular sieve assembly 213. The condensate generated after the high-temperature and high-pressure steam exchanges heat with the air is discharged from the air preheater 31 through the condensate recovery pipe 34.

[0062] The desuperheater and pressure reducer 35 is connected to the steam conveying pipeline 32 and is used to reduce the temperature and pressure of high-temperature and high-pressure steam when it passes through, so as to make the steam supplied by external equipment more stable.

[0063] The hot air blower 36 is connected to the cold air conveying pipe 33 and is used to draw outside air along the cold air conveying pipe 33 to the air preheater 31.

[0064] The two ends of the first hot air conveying pipe 37 are connected to the first air inlet 111 and the air preheater 31, respectively, and are used to convey the hot air obtained by heat exchange in the air preheater 31 to the first water vapor adsorption device 11, and use the hot air to purge and regenerate the first molecular sieve component 113 at high temperature.

[0065] The two ends of the second hot air conveying pipe 38 are connected to the second air inlet 211 and the air preheater 31, respectively, and are used to convey the hot air obtained by heat exchange in the air preheater 31 to the second water vapor adsorption device 21, and use the hot air to purge and regenerate the second molecular sieve component 213 at high temperature.

[0066] The urea hydrolysis product gas treatment system provided in this application adopts the design of a hot air supply mechanism 3. When the first molecular sieve component 113 and the second molecular sieve component 213 are not performing water vapor adsorption, they can be regenerated by high-temperature purging of hot air produced by the hot air supply mechanism 3, gradually restoring the water vapor adsorption function, so that the urea hydrolysis product gas treatment system achieves the technical effect of repeated use and repeated adsorption of water vapor.

[0067] In the above technical solution, in order to control the alternating operation of the first water vapor adsorption device 11 and the second water vapor adsorption device 21, the first molecular sieve component 113 and the second molecular sieve component 213 are regenerated alternately, thereby keeping the urea hydrolysis product gas treatment system in working condition; the urea hydrolysis product gas treatment system also includes a molecular sieve regeneration control mechanism: the molecular sieve regeneration control mechanism includes: a first pressure sensor 41, a second pressure sensor 42, a first product gas input valve 43, a second product gas input valve 44, a first hot air regulating valve 45, a second hot air regulating valve 46, a product gas input valve control module 47, and a molecular sieve regeneration control module 48;

[0068] The first pressure sensor 41 is connected to the first dry product gas output pipe 13 and is used to detect the product gas pressure difference near the pipe opening of the first dry product gas output pipe 13. When the first molecular sieve component 113 is close to saturation, its interior is occupied by moisture, which increases the airflow resistance in the first water vapor adsorption device 11 and causes the pressure difference to rise. By reading the reading of the first pressure sensor 41, the rise in pressure difference can be obtained, thereby determining whether the first molecular sieve component 113 is close to saturation.

[0069] Understandably, the second pressure sensor 42 is connected to the second dry product gas output pipe 23 and is used to detect the product gas pressure difference near the pipe opening of the second dry product gas output pipe 23.

[0070] The first product gas input valve 43 is connected to the first product gas branch pipeline 12 and is used to control the on / off state of the first product gas branch pipeline 12, that is, the state of the hydrolysis reactor 5 supplying product gas to the first water vapor adsorption device 11.

[0071] The second product gas input valve 44 is connected to the second product gas branch pipeline 22 and is used to control the on / off state of the second product gas branch pipeline 22, that is, the state of the hydrolysis reactor 5 supplying product gas to the second water vapor adsorption device 21.

[0072] The first hot air regulating valve 45 is connected to the first hot air conveying pipe 37 and is used to control the on / off state of the first hot air conveying pipe 37, that is, the state of the air preheater 31 conveying hot air to the first water vapor adsorption device 11.

[0073] The second hot air regulating valve 46 is connected to the second hot air conveying pipe 38 and is used to control the on / off state of the first hot air conveying pipe 37, that is, the state of the air preheater 31 conveying hot air to the second water vapor adsorption device 21.

[0074] The product gas input valve control module 47 is communicatively connected to the first pressure sensor 41, the second pressure sensor 42, the first product gas input valve 43, and the second product gas input valve 44. The product gas input valve control module 47 acquires the electrical signals output by the first pressure sensor 41 and the second pressure sensor 42 after detecting pressure difference changes, and determines the state of the first molecular sieve assembly 113 and the second molecular sieve assembly 213 based on the electrical signals. When the first molecular sieve assembly 113 is determined to be in a saturated state, the module controls the first product gas input valve 43 to close and the second product gas input valve 44 to open, stopping the supply of product gas to the first water vapor adsorption device 11. When the second molecular sieve assembly 213 is determined to be in a saturated state, the module controls the second product gas input valve 44 to close and the first product gas input valve 43 to open, stopping the supply of product gas to the second water vapor adsorption device 21.

[0075] The molecular sieve regeneration control module 48 is communicatively connected to the first pressure sensor 41, the second pressure sensor 42, the first hot air regulating valve 45, and the second hot air regulating valve 46. The module acquires the electrical signals output by the first and second pressure sensors 41 and 42 after detecting pressure difference changes, and determines the state of the first molecular sieve assembly 113 and the second molecular sieve assembly 213 based on these signals. When the first molecular sieve assembly 113 is determined to be in a saturated state, the module controls the opening of the first hot air regulating valve 45 and the closing of the second hot air regulating valve 46, allowing hot air to enter the first water vapor adsorption device 11 and regenerate the first molecular sieve assembly 113 through high-temperature purging. When the second molecular sieve assembly 213 is determined to be in a saturated state, the module controls the opening of the second hot air regulating valve 46 and the closing of the first hot air regulating valve 45, allowing hot air to enter the second water vapor adsorption device 21 and regenerate the second molecular sieve assembly 213 through high-temperature purging.

[0076] As one embodiment of this application, during the initial startup of the urea hydrolysis product gas treatment system, both the first molecular sieve component 113 and the second molecular sieve component 213 are in an unsaturated state. At this time, the first product gas inlet valve 43 is in the open state, while the second product gas inlet valve 44, the first hot air regulating valve 45, and the second hot air regulating valve 46 are all in the closed state. The product gas generated after the urea solution in the hydrolysis reactor 5 is hydrolyzed enters the first water vapor adsorption device 11 through the product gas pipeline 6 and the first product gas branch pipeline 12. After the product gas is dehydrated in the first water vapor adsorption device 11, it goes to the metering and distribution module 7 through the first dried product gas outlet pipeline 13.

[0077] When the first molecular sieve component 113 approaches saturation, its pores are filled with moisture, leading to increased airflow resistance and a rise in pressure differential. After detecting the change in pressure differential, the first pressure sensor 41 sends an electrical signal to the product gas input valve control module 47 and the molecular sieve regeneration control module 48. Upon receiving the electrical signal, the molecular sieve regeneration control module 48 and the product gas input valve control module 47 control the closure of the first product gas input valve 43 and the opening of the second product gas input valve 44 and the first hot air regulating valve 45. The product gas enters the second water vapor adsorption device 21 and passes through the second molecular sieve component 213 to remove moisture. At this time, the second hot air regulating valve 46 is in the closed state. Hot air enters the first water vapor adsorption device 11 through the first hot air delivery pipe 37 to purge and regenerate the first molecular sieve component 113 at high temperature. After the first molecular sieve component 113 completes regeneration, the molecular sieve regeneration control module 48 controls the closure of the first hot air regulating valve 45.

[0078] When the second molecular sieve assembly 213 reaches saturation, the product gas input valve control module 47 and the molecular sieve regeneration control module 48 control the closure of the second product gas input valve 44 and the first hot air regulating valve 45, and open the first product gas input valve 43 and the second hot air regulating valve 46; the product gas enters the first water vapor adsorption device 11 and removes moisture through the first molecular sieve assembly 113; the hot air enters the second water vapor adsorption device 21 through the second hot air delivery pipe 38 to regenerate the second molecular sieve assembly 213 by high-temperature purging.

[0079] The urea hydrolysis product gas treatment system provided in this application adopts a molecular sieve regeneration control mechanism to control the first water vapor adsorption device 11 and the second water vapor adsorption device 21 to alternately switch to perform water vapor adsorption work on the product gas. The first molecular sieve component 113 and the second molecular sieve component 213 are regenerated alternately, so that at least one of the first water vapor adsorption device 11 and the second water vapor adsorption device 21 is in an unsaturated working condition, thereby achieving the technical effect of continuous operation of the urea hydrolysis product gas treatment system.

[0080] To ensure that the product gas can fully contact the surface of the molecular sieve assembly when passing through the first molecular sieve assembly 113, thereby improving the adsorption efficiency of water vapor; as a preferred embodiment of this application, the first molecular sieve assembly 113 adopts a layered structure, which includes: a primary molecular sieve 1131, a secondary molecular sieve 1132, and a tertiary molecular sieve 1133.

[0081] The first-stage molecular sieve 1131 is located inside the first water vapor adsorption device 11 near the first air inlet 111. The adsorbent filling density of the first-stage molecular sieve 1131 is 0.60 kg / L to 0.65 kg / L. The first-stage molecular sieve 1131 is used to initially adsorb most of the moisture in the product gas and reduce airflow resistance, maintaining the product gas flow rate. The second-stage molecular sieve 1132 has an adsorbent filling density of 0.65 kg / L to 0.70 kg / L, used to further improve the water vapor adsorption efficiency. The third-stage molecular sieve 1133 is located inside the first water vapor adsorption device 11 near the first air outlet 112. The adsorbent filling density of the third-stage molecular sieve 1133 is 0.70 kg / L to 0.75 kg / L, used to ensure that the remaining water vapor in the product gas is completely adsorbed, avoiding water vapor condensation in the subsequent pipeline. It can be understood that the second molecular sieve assembly 213 can adopt a layered structure that matches the first molecular sieve assembly 113.

[0082] In a preferred embodiment of this application, a first flow indicator 121 is connected to the side of the first product gas branch pipe 12 near the first air inlet 111; a second flow indicator 221 is connected to the side of the second product gas branch pipe 22 near the second air inlet 211; the first flow indicator 121 and the second flow indicator 221 are respectively used to monitor the flow rate of the product gas in the corresponding pipes, so that the staff can promptly detect changes in the flow rate in the pipes caused by pipe blockage, leakage and other problems.

[0083] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A urea hydrolysis product gas treatment system, wherein the urea hydrolysis product gas treatment system is connected to the product gas pipeline between the hydrolysis reactor and the metering and distribution module, characterized in that, The urea hydrolysis product gas treatment system includes: The first water vapor adsorption device is a tubular structure with a first air inlet and a first air outlet at its two ends. The first water vapor adsorption device is equipped with a first molecular sieve component for adsorbing product gas water vapor. The first product gas branch pipeline has one end connected to the first air inlet and the other end connected to the product gas pipeline, which is used to transport the product gas in the product gas pipeline to the first water vapor adsorption device. The first drying product gas output pipeline has one end connected to the first gas outlet and the other end connected to the metering and distribution module. The second water vapor adsorption device is a tubular structure with a second air inlet and a second air outlet at its two ends. The second water vapor adsorption device is equipped with a second molecular sieve component for adsorbing product gas and water vapor. The second product gas branch pipeline has one end connected to the second air inlet and the other end connected to the product gas pipeline. The second dry product gas output pipe has one end connected to the second gas outlet and the other end connected to the first dry product gas output pipe, so that the product gas flows into the first dry product gas output pipe and is transported to the metering and distribution module through the first dry product gas output pipe.

2. The urea hydrolysis product gas treatment system according to claim 1, characterized in that, The urea hydrolysis product gas treatment system further includes a hot air supply mechanism for drying the first molecular sieve assembly and the second molecular sieve assembly; the hot air supply mechanism includes: Air preheater; A steam delivery pipeline, which is connected to the air preheater, is used to deliver steam to the air preheater; A cold air delivery pipeline, which is connected to the air preheater, is used to deliver cold air to the air preheater for heat exchange with steam. A condensate recovery pipe is connected to the air preheater and is used to discharge the condensate generated after steam heat exchange away from the air preheater. The first hot air delivery pipe has its two ends connected to the first air inlet and the air preheater, respectively, and is used to deliver hot air to the first water vapor adsorption device. The second hot air delivery pipe, with its two ends connected to the second air inlet and the air preheater respectively, is used to deliver hot air to the second water vapor adsorption device.

3. The urea hydrolysis product gas treatment system according to claim 2, characterized in that, The hot air supply mechanism also includes: A desuperheating and pressure reducing device, which is connected to the steam conveying pipeline; A hot air blower, which is connected to the cold air delivery duct.

4. The urea hydrolysis product gas treatment system according to claim 2, characterized in that, The urea hydrolysis product gas treatment system further includes a molecular sieve regeneration control mechanism; the molecular sieve regeneration control mechanism includes: The first pressure sensor is connected to the first dry product gas output pipe and is used to detect the product gas pressure difference at the pipe opening of the first dry product gas output pipe and output an electrical signal. The second pressure sensor is connected to the second dry product gas output pipe and is used to detect the product gas pressure difference at the pipe opening of the second dry product gas output pipe and output an electrical signal. The first product gas input valve is connected to the first product gas branch pipeline and is used to control the on / off state of the first product gas branch pipeline. The second product gas inlet valve is connected to the second product gas branch pipeline and is used to control the on / off state of the second product gas branch pipeline. A first hot air regulating valve is connected to the first hot air delivery pipeline and is used to control the on / off state of the first hot air delivery pipeline. The second hot air regulating valve is connected to the second hot air delivery pipeline and is used to control the on / off state of the second hot air delivery pipeline. The product gas input valve control module is communicatively connected to the first pressure sensor, the second pressure sensor, the first product gas input valve, and the second product gas input valve. The product gas input valve control module controls and changes the opening and closing states of the first product gas input valve and the second product gas input valve according to the electrical signals output by the first pressure sensor and the second pressure sensor. A molecular sieve regeneration control module is communicatively connected to the first pressure sensor, the second pressure sensor, the first hot air regulating valve, and the second hot air regulating valve, respectively. The molecular sieve regeneration control module controls the opening and closing states of the first hot air regulating valve and the second hot air regulating valve according to the electrical signals output by the first pressure sensor and the second pressure sensor.

5. The urea hydrolysis product gas treatment system according to claim 1, characterized in that, The first molecular sieve assembly is located between the first inlet end and the first outlet end, and the first molecular sieve assembly includes: A primary molecular sieve is located on the side of the first water vapor adsorption device near the first air inlet, and is used to adsorb water vapor in the product gas and maintain the product gas flow rate. A secondary molecular sieve is located in the middle section of the first water vapor adsorption device; The three-stage molecular sieve is located on the side of the first water vapor adsorption device near the first gas outlet, and is used to adsorb the remaining water vapor in the product gas.

6. The urea hydrolysis product gas treatment system according to claim 5, characterized in that, The adsorbent packing density of the primary molecular sieve is 0.60 kg / L to 0.65 kg / L; the adsorbent packing density of the secondary molecular sieve is 0.65 kg / L to 0.70 kg / L; and the adsorbent packing density of the tertiary molecular sieve is 0.70 kg / L to 0.75 kg / L.

7. The urea hydrolysis product gas treatment system according to claim 1, characterized in that, A first flow indicator is connected to the side of the first product gas branch pipe near the first air inlet; a second flow indicator is connected to the side of the second product gas branch pipe near the second air inlet.

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