Liquefied natural gas regasification ammonia removal system

Abstract

The utility model discloses liquefied natural gas regenerative gas ammonia removal system, including natural gas regenerative gas heater, and the shell course export of regenerative gas heater is connected with dehydration tower through the air pipe, and the inlet pipe of regenerative gas heater is connected with the water supply pipe of bypass connection on the shell course import connection, and the water supply pipe transports the condensate water generated by boiler to the inlet pipe and removes the ammonia gas in regenerative gas, and the utility model realizes the efficient removal of ammonia gas in regenerative gas through the water supply pipe to the inlet pipe of the condensate water generated by boiler, effectively solves the system resistance increase, equipment corrosion and pipeline blockage problem caused by the ammonia content overproof, has the obvious advantage of improving the process stability and security.

Description

Technical Field

[0001] This utility model relates to the field of natural gas regeneration, specifically to an ammonia removal system for liquefied natural gas regeneration. Background Technology

[0002] In the adsorption process of a natural gas liquefaction unit, the regenerated natural gas is heated by a regenerated gas heater and then transported to a dehydration tower for drying before entering a regenerated gas separator for subsequent separation. However, in actual operation, it was found that the system resistance increased significantly when the natural gas entered the liquefaction cold box, leading to a decrease in process stability and affecting overall efficiency. In-depth analysis revealed an abnormally high concentration of ammonia (18000 mg / L) in the condensate produced by the regenerated gas separator, indicating that the ammonia content in the regenerated gas entering the regenerated gas heater was severely excessive. The presence of ammonia caused blockage in the liquefaction cold box, requiring a shutdown for reheating. A single reheating operation took 5 days, resulting in a direct loss of 6.9 million yuan. Utility Model Content

[0003] To address the aforementioned problems, this utility model provides an ammonia removal system for liquefied natural gas regeneration gas.

[0004] This utility model is achieved through the following technical solution:

[0005] The natural gas regenerated gas ammonia removal system includes a natural gas regenerated gas heater. The shell-side outlet of the regenerated gas heater is connected to a dehydration tower via an outlet pipe. A water supply pipe is bypassed on the inlet pipe connected to the shell-side inlet of the regenerated gas heater. The water supply pipe transports the condensate generated by the boiler to the inlet pipe to remove ammonia from the regenerated gas.

[0006] Furthermore, this application also proposes that a U-shaped pipe be installed on the air intake pipe, and the U-shaped pipe be connected to the water supply pipe outlet through multiple fan-shaped spray pipes.

[0007] Furthermore, this application also proposes that the bottom of the U-shaped tube is connected to the top inlet of the dehydration tower via a guide pipe.

[0008] Furthermore, this application also proposes that a nozzle covering the air cross section be provided at the connection between the spray pipe and the U-shaped pipe.

[0009] Furthermore, this application also proposes that control valves be installed on both the water supply pipe and the diversion pipe.

[0010] Compared with existing technologies, the beneficial effects of this utility model are as follows: This utility model achieves efficient removal of ammonia from regenerated gas by transporting the condensate generated by the boiler to the air inlet pipe through the water supply pipe, effectively solving the problems of increased system resistance, equipment corrosion and pipeline blockage caused by excessive ammonia content, and has significant advantages in improving process stability and safety. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the system of this utility model;

[0012] Figure 2 This is a schematic diagram of the spray pipe connection in this practical application;

[0013] In the diagram: 1. Regenerated gas heater; 2. Inlet pipe; 3. Outlet pipe; 4. Dehydration tower; 5. Water supply pipe; 6. Control valve; 7. U-shaped pipe; 8. Spray pipe; 9. Guide pipe. Detailed Implementation

[0014] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0015] like Figure 1 As shown in the embodiment, the application proposes a liquefied natural gas regenerated gas ammonia removal system, including a natural gas regenerated gas heater 1. The shell-side outlet of the regenerated gas heater 1 is connected to a dehydration tower 4 through an outlet pipe 3. A water supply pipe 5 is bypassed on the inlet pipe 2 connected to the shell-side inlet of the regenerated gas heater 1. The water supply pipe 5 transports the condensate generated by the boiler to the inlet pipe 2 to remove ammonia from the regenerated gas.

[0016] By installing a bypass water supply pipe 5 on the inlet pipe 2, using a 20mm diameter pipe, boiler condensate is directly introduced into the regenerated gas flow path, achieving efficient ammonia dissolution and removal. This reduces the ammonia content from 18000mg / L to 300-500mg / L, effectively curbing the problem of increased cold box resistance and blockage caused by rising ammonia content. Compared to the problem of increased natural gas resistance due to excessive ammonia content in the prior art, this embodiment avoids ammonia deposition, blockage, or corrosion in subsequent equipment by performing ammonia removal treatment before the gas enters the heater, thus ensuring the continuous and stable operation of the system. Furthermore, the design of connecting the shell-side outlet to the dehydration tower 4 via the outlet pipe 3 further ensures that the ammonia-removed gas can smoothly enter the drying process, maintaining the overall process smoothness.

[0017] This application further proposes that a U-shaped pipe 7 be installed on the air intake pipe 2, and the U-shaped pipe 7 be connected to the outlet of the water supply pipe 5 through multiple fan-shaped spray pipes 8.

[0018] A U-shaped pipe 7 is added to the inlet pipe 2, altering the flow characteristics of the regenerated gas and creating a stable, slow-flow region in the curved section, effectively reducing the impact of sudden changes in airflow velocity on the mixing effect. The spray pipes 8, arranged in a multi-fan shape to match the geometry of the U-shaped pipe 7, ensure uniform spraying of condensate from multiple angles, significantly improving ammonia dissolution efficiency. The condensate supplied by the water supply pipe 5, after being evenly distributed through the spray pipes 8, fully reacts with the regenerated gas within the U-shaped pipe 7. Unevaporated water is collected using the liquid collection characteristics at the bottom of the U-shaped pipe 7, preventing it from directly entering subsequent systems. This structural design, without increasing additional energy consumption, enhances the uniformity of water-gas contact and the depth of reaction, fundamentally alleviating the system resistance problem caused by excessive ammonia content. Through the above technical solutions, a full reaction between condensate and ammonia in the regenerated gas is achieved, effectively solving the problem of incomplete ammonia removal.

[0019] This application further proposes that the bottom of the U-shaped tube 7 is connected to the top inlet of the dehydration tower 4 via the guide pipe 9.

[0020] Connecting the bottom of U-tube 7 to the guide pipe 9 at the top inlet of dehydration tower 4 effectively solves the system problem caused by the accumulation of ammonia-containing liquid. The bottom of U-tube 7 serves as a natural liquid collection point, its structural characteristics causing the condensate from ammonia absorption after spraying to concentrate there under gravity. Guide pipe 9 provides a dedicated channel, ensuring that liquid does not stagnate within U-tube 7, avoiding the risk of blockage and ammonia re-release. This design, based on the low-point location of the bottom of U-tube 7, enables timely liquid removal and continuous system operation, thereby maintaining the stability and efficiency of the regenerated gas ammonia removal process.

[0021] This application further proposes that a nozzle covering the air cross section be provided at the connection between the spray pipe 8 and the U-shaped pipe 7.

[0022] The spray pipe 8, with its spray nozzles covering the gas cross-section and arranged in a fan shape, allows the water flow to form a uniform water curtain within the U-shaped pipe 7, ensuring full contact with the ammonia in the regeneration gas. This design fully utilizes the arrangement characteristics of the spray pipe 8, optimizing the mixing effect of water and regeneration gas through the coverage of the nozzles, effectively solving the problem of uneven water flow distribution. Simultaneously, the nozzle design ensures uniform water flow distribution, significantly improving the system's ammonia removal efficiency and providing a reliable guarantee for the stable operation of subsequent equipment. Furthermore, this scheme, in conjunction with the structure of the water supply pipe 5 and the U-shaped pipe 7, further enhances the ammonia dissolution effect, preventing problems such as increased system resistance or decreased separation efficiency due to excessive ammonia content.

[0023] This application further proposes that control valves 6 are installed on both the water supply pipe 5 and the diversion pipe 9.

[0024] The control valve 6 on the water supply pipe 5 can adjust the injection rate of condensate in real time according to the changes in regeneration gas flow and ammonia concentration, ensuring that the water volume is always maintained within the optimal range. This avoids both excessive water injection leading to gas dilution or resource waste, and insufficient water injection causing incomplete ammonia removal. At the same time, the control valve 6 on the guide pipe 9 maintains the liquid level balance in the U-shaped pipe 7 by regulating the discharge rate of the liquid after ammonia removal, effectively preventing gas short-circuiting or liquid backflow from interfering with the regeneration gas flow, thereby ensuring the stability of the inlet conditions of the dehydration tower 4.

[0025] The implementation principle of the ammonia removal system for liquefied natural gas regenerated gas in this application embodiment is as follows:

[0026] Regenerated natural gas is heated by regenerated gas heater 1 and then enters the dehydration tower 4 for further heating. A bypass water supply pipe 5 is installed on the inlet pipe 2 connected to the shell-side inlet of regenerated gas heater 1 to introduce condensate from the boiler into the inlet pipe 2, thereby removing ammonia from the regenerated gas. The condensate, as the ammonia removal medium, efficiently dissolves ammonia due to its suitable temperature and lack of impurities, preventing ammonia from depositing or corroding in subsequent equipment. Furthermore, after the condensate is injected into the inlet pipe 2 through the water supply pipe 5, it mixes thoroughly with the regenerated gas before entering the regenerated gas heater 1, ensuring effective absorption of ammonia. This reduces the ammonia content in the regenerated gas, solving the problem of increased natural gas resistance caused by excessive ammonia content. Specifically, the shell-side outlet of regenerated gas heater 1 is connected to the dehydration tower 4 through the outlet pipe 3, allowing the ammonia-removed gas to smoothly enter the drying process, thus maintaining the continuity and stability of the overall system operation. The design of the water supply pipe 5 not only achieves efficient ammonia removal but also avoids interference with the main process, ensuring the normal operation of the system.

[0027] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A liquefied natural gas regenerated gas ammonia removal system, comprising a natural gas regenerated gas heater (1), wherein the shell-side outlet of the regenerated gas heater (1) is connected to a dehydration tower (4) via an outlet pipe (3), characterized in that: A water supply pipe (5) is bypassed to the air inlet pipe (2) connected to the shell side inlet of the regenerated gas heater (1). The water supply pipe (5) transports the condensate generated by the boiler to the air inlet pipe (2) to remove ammonia from the regenerated gas.

2. The liquefied natural gas regeneration gas ammonia removal system according to claim 1, characterized in that: A U-shaped pipe (7) is installed on the air inlet pipe (2), and the U-shaped pipe (7) is connected to the outlet of the water supply pipe (5) through multiple fan-shaped spray pipes (8).

3. The liquefied natural gas regeneration gas ammonia removal system according to claim 2, characterized in that: The bottom of the U-shaped tube (7) is connected to the top inlet of the dehydration tower (4) via a guide pipe (9).

4. The liquefied natural gas regeneration gas ammonia removal system according to claim 2, characterized in that: A nozzle covering the air cross section is provided at the connection between the spray pipe (8) and the U-shaped pipe (7).

5. The liquefied natural gas regeneration gas ammonia removal system according to claim 1, characterized in that: Control valves (6) are installed on both the water supply pipe (5) and the diversion pipe (9).

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