Novel LNG vaporizer assembly

Abstract

The utility model relates to a novel LNG (Liquefied Natural Gas) vaporizer assembly which comprises a composition analyzer, a refrigerant buffer tank and an LNG vaporizer group, the LNG vaporizer group is connected with an LNG feeding pipeline; an LNG feeding valve is arranged on the LNG feeding pipeline; a sampling point of the composition analyzer is positioned at the front end of the LNG feeding valve; a liquid-phase refrigerant outlet of the LNG vaporizer group is connected with the refrigerant user group; and the refrigerant user group is connected with the refrigerant buffer tank. The LNG vaporizer assembly is simple in structure, small in investment, suitable for LNG raw materials of various components and safe and stable in operation. A special working medium propylene or ethylene is selected as a working medium for recycling LNG cold energy, a large amount of high-grade and multi-grade cooling capacity can be provided for other devices after a large amount of LNG cold energy is recycled, the energy consumption of the device is greatly reduced, and recycling of resources is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of petrochemical industry, and in particular relates to a novel LNG vaporizer component for a special working medium, specifically to a novel LNG vaporizer component which realizes the vaporization of LNG and the recovery and utilization of the cold energy of LNG. Background Art

[0002] LNG vaporizers are heat exchangers specifically designed for the vaporization of liquefied natural gas (LNG). They are primarily used in large coastal LNG receiving terminals, LNG liquefaction plants, LNG vaporization stations, and LNG refueling stations. They are key equipment for achieving the vaporization function. LNG vaporizers require different structural designs depending on the properties and composition of the LNG. Common LNG vaporizers include open rack vaporizers (ORVs), submerged combustion vaporizers (SCVs), intermediate fluid vaporizers (IFVs), air-heated vaporizers, forced draft vaporizers, hot air vaporizers, vacuum steam vaporizers (VSVs), intermediate medium air-heated vaporizers, and hot water bath vaporizers. These vaporizers are relatively complex in structure. Some utilize aluminum alloy heat transfer tubes with star-shaped cross-sections and spiral rods inside and fins on the outside. Others utilize spirally wound heat exchangers, resulting in complex manufacturing structures and high equipment costs. Furthermore, none of these vaporizers are efficient enough to accommodate all LNG feedstock compositions.

[0003] LNG vaporizers are also categorized by the heat medium used to vaporize LNG. Common heat media include air, river or sea water, natural gas combustion, electric heating, and factory waste heat. These heat media are used solely to vaporize LNG, but the LNG's cooling energy is not recovered or reused, resulting in wasted cooling energy. Low-temperature LNG releases a significant amount of cooling energy during vaporization, approximately 850 kJ / kg. This cooling energy should be fully recovered to conserve energy and improve economic efficiency.

[0004] Traditional petroleum and chemical plants often utilize ethylene compressors when olefin separation units are involved. The refrigeration energy provided by the propylene compressor is used to pre-cool the separation system's feedstock or condense the overhead materials. A typical propylene circulating refrigeration compressor can provide refrigerant at four temperature levels: 5°C, -8°C, -25°C, and -40°C for different systems. Depending on the composition of the separated materials, some units may require even lower-temperature ethylene refrigeration compressors to provide separation energy. The compressor system is critical to the stable operation of the olefin separation unit and is also the core equipment within the entire unit, requiring significant investment, a long manufacturing cycle, and high safety requirements. It is a top priority in the overall process design; however, the equipment is complex and the investment cost is high.

[0005] Therefore, it is of great significance to develop a new LNG vaporizer assembly with strong adaptability to LNG raw materials and low equipment investment cost. Utility Model Content

[0006] In view of this, the present invention aims to provide a novel LNG vaporizer assembly, which adopts a special working fluid, such as ethylene or propylene, to solve at least one problem in the above-mentioned background technology.

[0007] In order to achieve the above-mentioned purpose, the technical solution of the utility model is achieved as follows:

[0008] A new type of LNG vaporizer assembly, including a composition analyzer, a refrigerant buffer tank, and an LNG vaporizer group;

[0009] The LNG vaporizer group is connected to an LNG feed pipeline; an LNG feed valve is provided on the LNG feed pipeline; the sampling point of the composition analyzer is located at the front end of the LNG feed valve;

[0010] The liquid-phase refrigerant outlet of the LNG vaporizer group is connected to the refrigerant user group; the refrigerant user group is connected to the refrigerant buffer tank, and the refrigerant buffer tank is connected to the gas-phase refrigerant inlet of the LNG vaporizer group.

[0011] Preferably, the LNG vaporizer group includes a heavy LNG vaporizer and a light LNG vaporizer;

[0012] The heavy LNG inlet of the heavy LNG vaporizer and the light LNG inlet of the light LNG vaporizer are connected to an LNG feed pipeline;

[0013] The LNG feed valve is connected to the heavy LNG inlet of the heavy LNG vaporizer or the light LNG inlet of the light LNG vaporizer respectively;

[0014] The first liquid-phase refrigerant outlet located at the light LNG vaporizer and the second liquid-phase refrigerant outlet located at the heavy LNG vaporizer are respectively connected to the refrigerant user groups;

[0015] The refrigerant buffer tank is respectively connected to a first gas-phase refrigerant inlet on the light LNG vaporizer and a second gas-phase refrigerant inlet on the heavy LNG vaporizer.

[0016] This new LNG vaporizer assembly features a simple structure and low investment. It is suitable for LNG feedstocks of various compositions and operates safely and stably. By selecting special working fluids such as propylene or ethylene as the working fluid for recovering LNG cold energy, the recovered LNG cold energy can provide a large amount of high-grade, multi-grade cold energy for other devices, significantly reducing the device's energy consumption and achieving resource recycling.

[0017] Preferably, the LNG vaporizer assembly further comprises an LNG separation tank;

[0018] The liquid phase outlet of the LNG separation tank is connected to the LNG feed pipeline; the liquid phase outlet of the LNG separation tank is provided with an LNG pump;

[0019] An LNG gas delivery pipe is provided on the top of the LNG separation tank;

[0020] The LNG separation tank is connected to the light LNG outlet of the light LNG vaporizer and the heavy LNG outlet of the heavy LNG vaporizer respectively.

[0021] Preferably, the LNG vaporizer assembly further comprises a refrigerant storage tank, which is respectively connected to the first liquid-phase refrigerant outlet located at the light LNG vaporizer, the second liquid-phase refrigerant outlet located at the heavy LNG vaporizer and the refrigerant user group.

[0022] Preferably, the detection signal of the composition analyzer is used to control the opening and closing state of the LNG feed valve.

[0023] Furthermore, a refrigerant pump is provided between the refrigerant storage tank and the refrigerant user group; a start-up refrigerant inlet is provided on the refrigerant storage tank for connecting the start-up refrigerant pipeline;

[0024] The refrigerant pump is connected to the refrigerant user group through a circulating liquid-phase refrigerant pipe, and the refrigerant user group is connected to the refrigerant buffer tank through a circulating gas-phase refrigerant pipe;

[0025] And / or, it also includes a start-up vaporizer, one end of the start-up vaporizer is connected to the refrigerant pump, and the other end is connected to the refrigerant buffer tank;

[0026] The refrigerant user group is connected in parallel with the start-up vaporizer;

[0027] And / or, the refrigerant buffer tank is connected to the light LNG vaporizer and the heavy LNG vaporizer respectively through refrigerant valves;

[0028] And / or, the detection signal of the component analyzer is used to control the opening and closing state of the refrigerant valve.

[0029] and / or, when the composition analyzer detects that the Cl content of the LNG feedstock is greater than 95%, the LNG feed valve is opened to the light LNG inlet connected to the shell side of the light LNG vaporizer, and simultaneously, the refrigerant valve is opened to the first gas-phase refrigerant inlet connected to the tube side of the light LNG vaporizer;

[0030] When the composition analyzer detects that the C1 content of the LNG raw material is less than or equal to 95%, the LNG feed valve is connected to the heavy LNG inlet connected to the heavy LNG vaporizer tube side, and at the same time, the refrigerant valve is connected to the second gas phase refrigerant inlet connected to the heavy LNG vaporizer shell side;

[0031] And / or, if the processing capacity of LNG raw materials increases, the light LNG vaporizer and the heavy LNG vaporizer are operated simultaneously.

[0032] Furthermore, the light LNG vaporizer includes a light LNG shell and a light LNG tube bundle. A plurality of U-shaped heat exchange tube bundles are provided in the light LNG shell. The heat exchange tubes are arranged horizontally in the light LNG shell. A light LNG outlet connected to the shell side of the light LNG vaporizer is provided on the top of the light LNG shell. The LNG raw material exchanges heat with the gas-phase refrigerant located in the tube side in the shell side of the light LNG vaporizer.

[0033] Furthermore, a first gas-phase refrigerant inlet is provided at the upper portion of the pipe box of the light LNG vaporizer, and a first liquid-phase refrigerant outlet is provided at the lower portion of the pipe box of the light LNG vaporizer. The first gas-phase refrigerant inlet is connected to the first liquid-phase refrigerant outlet through the pipe box, the tube sheet and the U-shaped heat exchange tube bundle;

[0034] The light LNG shell of the light LNG vaporizer includes a first-stage shell, a transition-stage shell, and a second-stage shell. The first-stage shell and the second-stage shell are connected by the transition-stage shell. The diameter of the first-stage shell is smaller than the diameter of the second-stage shell. The lowermost end of the first-stage shell is flush with the lowermost end of the second-stage shell.

[0035] The inlet end of the U-shaped heat exchange tube is located on one side of the first shell; the U-shaped end of the U-shaped heat exchange tube is located in the second shell;

[0036] Several staggered single-bow baffles and first support plates are provided between the light LNG tube bundle and the light LNG shell. In addition, an overflow weir is also provided in the light LNG shell, and the overflow weir is provided on the side close to the outer end of the U-bend.

[0037] Furthermore, a light LNG inlet is provided at the bottom of the light LNG shell of the light LNG vaporizer, a light LNG outlet is provided at the top of the light LNG shell, and a light LNG heavy component liquid phase outlet is also provided at the bottom of the light LNG shell; the light LNG inlet is arranged on a side close to the gas phase refrigerant inlet and outlet, and the light LNG gas phase outlet is arranged on a side away from the refrigerant inlet and outlet;

[0038] The light LNG inlet is located on a side of the overflow weir close to the pipe box, and the light LNG heavy component liquid phase outlet is located on a side of the overflow weir away from the pipe box;

[0039] The light LNG outlet is located at the top of the second-stage shell; the first gas-phase refrigerant inlet of the light LNG vaporizer is connected to the refrigerant buffer tank, the first liquid-phase refrigerant outlet of the light LNG vaporizer is connected to the refrigerant storage tank, the refrigerant storage tank is connected to the refrigerant pump, and the refrigerant pump delivers the liquid-phase refrigerant to the users of the petrochemical separation device for use, and the gas-phase refrigerant returns to the refrigerant buffer tank for recycling.

[0040] Furthermore, the heavy LNG vaporizer includes a heavy LNG shell and a heavy LNG tube bundle;

[0041] Several U-shaped heat exchange tube bundles are provided in the heavy LNG shell, and the U-shaped heat exchange tubes are arranged transversely in the heavy LNG shell;

[0042] The gas phase refrigerant exchanges heat with the LNG raw material located in the tube side of the heavy LNG vaporizer in the shell side of the heavy LNG shell.

[0043] Furthermore, a heavy LNG inlet is provided at the bottom of the pipe box of the heavy LNG vaporizer, and a heavy LNG outlet is provided at the top of the pipe box of the heavy LNG vaporizer, and the heavy LNG inlet and the heavy LNG outlet are connected through the pipe box, the tube sheet and the U-shaped heat exchange tube bundle;

[0044] An outer guide collar is provided on the shell side inlet of the heavy LNG vaporizer, and 2 to 3 air inlet grooves are evenly opened on the outer guide collar. The gas phase refrigerant is connected with the cavity between the shell side of the heavy LNG vaporizer through the air inlet grooves.

[0045] Furthermore, a second liquid-phase refrigerant outlet is provided at the bottom of the shell of the heavy LNG vaporizer;

[0046] The heavy LNG vaporizer has a heavy LNG shell with a number of single-bow or double-bow baffles, and the baffles have a number of through holes supporting the U-shaped heat exchange tube bundles;

[0047] The second gas-phase refrigerant inlet of the heavy LNG vaporizer is connected to the refrigerant buffer tank, and the second liquid-phase refrigerant outlet of the heavy LNG vaporizer is connected to the refrigerant storage tank.

[0048] After adopting the new LNG vaporizer assembly described in the utility model and using special working fluids such as ethylene or propylene as refrigerant, the power consumption during the operation of the device is significantly reduced, while the amount of circulating water is saved and the equipment investment cost is reduced;

[0049] Using the above-mentioned device, a light hydrocarbon recovery unit design optimization calculation shows that electricity consumption is reduced by 1598 kWh and circulating water consumption is saved by 905 t / h. Preliminary calculations show that compared to traditional propylene compressor refrigeration, equipment costs can be reduced by more than 20%.

[0050] Compared with the existing technology, the new LNG vaporizer assembly described in this utility model has the following advantages:

[0051] The advantages of simple process, low energy consumption, low investment and stable operation are shown in the optimized design results of the light hydrocarbon recovery device. After adopting the new LNG vaporizer assembly described in the utility model, the power consumption during the operation of the device is significantly reduced, while the amount of circulating water is saved and the equipment investment cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0053] Figure 1 This is an overall schematic diagram of a new LNG vaporizer assembly according to Example 1 of the present utility model;

[0054] Figure 2 This is a schematic diagram of the light LNG vaporizer described in Example 3 of the present utility model;

[0055] Figure 3 This is a schematic diagram of the heavy LNG vaporizer described in Example 4 of the present utility model;

[0056] Figure 4 This is a schematic diagram of the heavy LNG tube bundle described in Example 4 of the present invention.

[0057] Description of reference numerals:

[0058] 1. LNG separation tank; 2. LNG pump; 3. Composition analyzer; 4. LNG feed valve; 5. Heavy LNG vaporizer; 6. Light LNG vaporizer; 7. Refrigerant valve; 8. Refrigerant storage tank; 9. Refrigerant pump; 10. Refrigerant buffer tank; 11. Start-up vaporizer; 12. Refrigerant user group; 13. LNG raw material from the tank farm; 14. LNG gas delivery pipe; 15. Start-up refrigerant pipeline; 16. Circulating liquid-phase refrigerant pipe; 17. Circulating gas-phase refrigerant pipe; 19. Light LNG tube bundle; 20. Light LNG shell; 21. A gas-phase refrigerant inlet; 22. A first liquid-phase refrigerant outlet; 23. A transition section shell; 24. A single-bow baffle; 25. A first support plate; 26. A light LNG inlet; 27. A light LNG outlet; 28. An overflow weir; 29. A heavy component liquid-phase outlet; 30. A heavy LNG tube bundle; 31. A heavy LNG shell; 32. A heavy LNG inlet; 33. A heavy LNG outlet; 34. An outer guide collar; 35. An inlet groove; 36. A second gas-phase refrigerant inlet; 37. A second liquid-phase refrigerant outlet; 38. A baffle of a heavy LNG vaporizer. DETAILED DESCRIPTION

[0059] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0060] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0061] Example 1

[0062] like Figure 1This embodiment provides a novel LNG vaporizer assembly, including a composition analyzer 3, a refrigerant buffer tank 10, a heavy LNG vaporizer 5, and a light LNG vaporizer 6;

[0063] The heavy LNG inlet 32 of the heavy LNG vaporizer 5 and the light LNG inlet 26 of the light LNG vaporizer 6 are connected to LNG feed pipelines;

[0064] The LNG feed pipeline is provided with LNG feed valves 4, which are respectively connected to the heavy LNG inlet 32 of the heavy LNG vaporizer 5 or the light LNG inlet 26 of the light LNG vaporizer 6;

[0065] The sampling point of the composition analyzer 3 is located at the front end of the LNG feed valve 4;

[0066] The first liquid-phase refrigerant outlet 22 located at the light LNG vaporizer 6 and the second liquid-phase refrigerant outlet 37 located at the heavy LNG vaporizer 5 are respectively connected to the refrigerant user group 12;

[0067] The refrigerant user group 12 is connected to the refrigerant buffer tank 10 , and the refrigerant buffer tank 10 is respectively connected to the first gas-phase refrigerant inlet 21 located on the light LNG vaporizer 6 and the second gas-phase refrigerant inlet 36 located on the heavy LNG vaporizer 5 .

[0068] LNG feedstock from the boundary area is connected to the tube side of heavy LNG vaporizer 55 or the shell side of light LNG vaporizer 66 via an LNG feed pipeline. A composition analyzer 3 located on the LNG feed pipeline detects the composition of the LNG feedstock. The detection signal is used to control the opening and closing of the LNG feed valve 4, feeding the light LNG vaporizer 6 or heavy LNG vaporizer 5, respectively. The LNG feed valve 4 can be a three-way valve. The gaseous refrigerant exchanges heat with the LNG feedstock in the heavy LNG vaporizer 5 or light LNG vaporizer 6 to produce a liquid refrigerant using a special working fluid such as propylene or ethylene. After providing cooling to refrigerant user group 12, the liquid refrigerant enters the refrigerant buffer tank 10 and then re-enters the light LNG vaporizer 6 or heavy LNG vaporizer 5.

[0069] Example 2

[0070] In this embodiment, based on the embodiment 1, the novel LNG vaporizer assembly further includes an LNG separation tank 1;

[0071] The liquid phase outlet of the LNG separation tank 1 is connected to the LNG feed pipeline; the liquid phase outlet of the LNG separation tank 1 is provided with an LNG pump 2;

[0072] The top of the LNG separation tank 1 is provided with an LNG gas delivery pipe 14;

[0073] The LNG separation tank 1 is connected to the light LNG outlet 27 of the light LNG vaporizer 6 and the heavy LNG outlet 33 of the heavy LNG vaporizer 5 respectively.

[0074] The LNG raw material is vaporized by the light LNG vaporizer or the heavy LNG vaporizer and sent to the LNG separation tank 1. After being separated in the LNG separation tank 1, the gaseous LNG is sent out as a product, and the liquid LNG is pressurized by the LNG pump 2 and then merged into the LNG raw material main for recycling; at the same time, the liquid start-up refrigerant from the boundary area, which is propylene or ethylene, is loaded into the refrigerant storage tank 8 at one time. During the startup phase, it is sent into the startup vaporizer 11 through the refrigerant pump 9. The vaporized refrigerant is sent into the shell side of the heavy LNG vaporizer 5 or the pipe side of the light LNG vaporizer 6 through the refrigerant valve 7. The condensed liquid refrigerant returns to the refrigerant storage tank 8. After the system establishes pressure balance, the startup vaporizer 11 is cut off, and the refrigerant in the refrigerant storage tank 8 is sent to the nearby refrigerant user group 12 through the refrigerant pump 9. After being vaporized in the refrigerant user group 12, it is sent to the refrigerant buffer tank 10, and the above cycle is repeated to provide the refrigerant user group 12 with a continuous supply of cold energy. The LNG feed valve 4 and the refrigerant valve 7 simultaneously receive signals from the composition analyzer 3. The specific signals are: when the C1 content of the LNG raw material is less than or equal to 95%, the LNG feed valve 4 and the refrigerant valve 7 simultaneously open the valve channel leading to the light LNG vaporizer 6; when the C1 content of the LNG raw material is greater than 95%, the LNG feed valve 4 and the refrigerant valve 7 simultaneously open the valve channel leading to the heavy LNG vaporizer 5.

[0075] In actual use, either the light LNG vaporizer 6 or the heavy LNG vaporizer 5 can be used independently, depending on the actual situation. Alternatively, when the LNG processing capacity is large and peak usage is required, the three-way valves of the light LNG vaporizer 6 and the heavy LNG vaporizer 5 can be opened simultaneously, that is, the LNG vaporizer components can be activated simultaneously to increase the processing capacity. When the Cl content in the LNG feedstock is less than or equal to 95%, the material composition is complex and the boiling range is wide, which is defined as heavy LNG. At this time, the material enters the heavy LNG vaporizer 5 through the three-way valve. When the Cl content in the LNG feedstock is greater than 95%, the material composition is simple and the boiling range is small, which is defined as light LNG. At this time, the material is switched to the light LNG vaporizer 6 through the three-way valve.

[0076] Example 3

[0077] This embodiment is based on embodiment 2. Figure 2 As shown;

[0078] The light LNG vaporizer 6 includes a light LNG tube bundle 19 and a light LNG shell 20. The light LNG tube bundle 19 is a U-shaped heat exchange tube, with several light LNG tube bundles 19 arranged horizontally within the light LNG shell 20. Within the heat exchange tube bundle 19 of the light LNG vaporizer, the gaseous refrigerant exchanges heat with the light LNG feedstock located on the shell side. A first gaseous refrigerant inlet 21 is provided at the top of the light LNG vaporizer's tube box, and a first liquid-phase refrigerant outlet 22 is provided at the bottom of the tube box. The first gaseous refrigerant inlet 21 communicates with the light LNG vaporizer's tube bundle through the tube box and tube sheet, while the first liquid-phase refrigerant outlet 22 communicates with the light LNG vaporizer's tube bundle through the tube box and tube sheet. A transition section shell 23 is provided in the middle of the light LNG shell 20. Several staggered single-bow baffles 24 and a first support plate 25 are arranged between the light LNG shell 20 and the light LNG tube bundle 19. An overflow weir 28 is provided within the light LNG shell 20, located on the side away from the first liquid-phase refrigerant outlet. A single-bow baffle 24 is arranged on a side close to the refrigerant outlet and on a side of the transition section 23; a plurality of through holes are provided on the single-bow baffle 24 and the first support plate 25; a light LNG inlet 26 is provided at the bottom of the light LNG shell 20, and a light LNG outlet 27 is provided at the upper portion of the light LNG shell 20; the light LNG inlet 26 is provided on a side close to the refrigerant outlet, the light LNG outlet 27 is provided on a side away from the refrigerant outlet, and a heavy component liquid phase outlet 29 is provided at the bottom of the light LNG shell 20; the light LNG outlet 27 is provided on one side of the overflow weir 28, and the heavy component liquid phase outlet 29 is provided on the other side of the overflow weir 28; the first gas-phase refrigerant inlet 21 of the light LNG vaporizer 6 is connected to the refrigerant buffer tank 10 through a pipeline of the refrigerant valve 7, and the first liquid-phase refrigerant outlet 22 of the light LNG vaporizer 6 is connected to the refrigerant storage tank 8 and is sent to the refrigerant user group 12 through the refrigerant pump 9. The gas-phase refrigerant vaporized in the refrigerant user group 12 is circulated to the refrigerant buffer tank 10, thereby recycling the cold energy of the LNG in turn.

[0079] Example 4

[0080] This embodiment is based on embodiment 2. Figure 3 、 4 As shown;

[0081] The heavy LNG vaporizer 5 includes a heavy LNG shell 30 and a heavy LNG tube bundle 31; a plurality of U-shaped heat exchange tubes are provided in the heavy LNG shell 30, and a plurality of heat exchange tubes are arranged horizontally in the heavy LNG vaporizer shell 30, and the heavy LNG tube bundle 31 is arranged in the heavy LNG vaporizer shell 30; the gaseous refrigerant exchanges heat with the heavy LNG raw material located in the tube bundle in the shell side of the heavy LNG vaporizer. A heavy LNG inlet 32 is provided at the lower part of the pipe box of the heavy LNG vaporizer 5, and a heavy LNG outlet 33 is provided at the upper part of the pipe box of the heavy LNG vaporizer 5. The heavy LNG inlet 32 is connected to the heat exchange tube bundle through the pipe box and the tube sheet, and the heavy LNG outlet 33 is connected to the heat exchange tube bundle through the pipe box and the tube sheet; an outer guide collar 34 is provided on the heavy LNG shell 30; 2 to 3 inlet grooves 35 are evenly arranged on the outer guide collar 34 to facilitate a large amount of gas-phase refrigerant to evenly enter the second gas-phase refrigerant inlet 36 of the shell side of the heavy LNG vaporizer 5. The gas-phase refrigerant enters the heavy LNG shell 30 through the inlet groove 35, flows through the baffle 38 with several through holes, flows to the second liquid-phase refrigerant outlet 37 and is sent to the refrigerant storage tank 8, and is sent to the refrigerant user group 12 through the refrigerant pump 9. The gas-phase refrigerant after being vaporized in the refrigerant user group 12 is circulated and sent to the refrigerant buffer tank 10, so that the cold energy of LNG is recycled in sequence.

[0082] The LNG from the boundary area and the low-temperature special refrigerant undergo inter-wall heat exchange in the LNG vaporizer group. The propylene or ethylene condensed into liquid is pressurized by a low-temperature pump and divided into 2 or more levels according to the separation temperature requirements and properties of the refrigerant user group. Generally, it is divided into at least 2 levels, and the level above 5°C is one level. This level can switch the circulating water users in the original separation device to refrigerant users, which not only improves the heat exchange efficiency, but also greatly saves the consumption of circulating water. The other refrigerant classification can be divided into -8°C, -20°C, -40°C, -60°C and even -80°C refrigerant according to the actual needs of the device users. This not only realizes the hierarchical utilization of energy levels, but also reduces the investment cost of ultra-low temperature equipment and improves the heat exchange efficiency of the equipment.

[0083] A project example in a certain place

[0084] When the refrigerant is ethylene and the composition analyzer detects that the LNG raw material is heavy LNG as shown in Table 1, the simulation shows that the subcooling load is large, accounting for 50.71% of the total heat load. Therefore, under this working condition, it is necessary to fully consider the design of the subcooling section and the maximum recovery of cold capacity. In this application, in order to save investment and space, at this time, the heavy LNG raw material enters the heavy LNG vaporizer. The specific schematic diagram of the heavy LNG vaporizer equipment design is as follows Figure 3 、 4As shown, the bundle length of the heavy LNG heat exchange tubes is 7.5 meters, and the bundle diameter of the heavy LNG heat exchange tubes is 1.8 meters (the bundle diameter includes the sum of the tube diameter and the tube center distance); the shell side is evenly arranged with single-bow baffles with an opening rate of about 30% to 40%. In addition, due to the large gas volume at the shell side inlet, in order to avoid reducing the number of pipes due to the large opening of the shell side cylinder of the heavy LNG vaporizer and to prevent pipe vibration caused by excessive gas flow rate, this design sets a special guide device at the shell side inlet of the heavy LNG vaporizer. The outer guide ring 34 is 1.4 meters wide and 0.5 meters high. 2 to 3 grooves are symmetrically opened on the guide device to ensure stable flow of fluid and a reasonable structure of the heavy LNG vaporizer.

[0085] When the refrigerant is ethylene and the composition analyzer detects that the LNG raw material is light LNG as shown in Table 1, the material composition is simple and easy to vaporize. At this time, the light LNG raw material enters the light LNG vaporizer. The specific schematic diagram of the light LNG vaporizer equipment design is as follows Figure 2 As shown, the bundle length of the heat exchange tubes of the light LNG vaporizer is 7.5 meters, the bundle diameter of the light LNG vaporizer is 1.8 meters, and the shell diameter is 2.4 meters. Three single-bow baffles with an opening ratio of 30% to 40% are evenly arranged in the subcooling section of the shell of the light LNG vaporizer. Then, the water enters the vaporization section with a shell-side flow length of 5.5 meters. The first support plates are evenly arranged in the vaporization section to prevent the tube bundle from exceeding the maximum unsupported span and causing vibration. At the same time, an overflow weir 200 mm higher than the tube bundle is set at the end of the light LNG tube bundle. In order to prevent the accumulation of the heavy component liquid phase in the vaporizer, an opening needs to be set at the lower end of the overflow weir to ensure the safe and stable operation of the vaporizer.

[0086] Table 1 Light / Heavy LNG Raw Material Composition

[0087] Component, mol% Heavy LNG Light LNG C1 80.00％ 98.00％ C2 14.00％ 0.70％ C3 3.00％ 0.00％ C3+ 2.00％ 0.00％ N2 1.00％ 1.30％ Total 100.00％ 100.00％ Molecular weight 20.26 16.3

[0088] Note: C3+ is 0.9% iC4+, 0.9% nC4+, 0.1% iC5+, 0.1% nC5+.

[0089] By using the above-mentioned device of the present invention, it can be concluded from the design optimization calculation of the light hydrocarbon recovery device that the equipment cost of the above-mentioned device of the present invention can be reduced by more than 20% compared with the traditional refrigeration using a propylene compressor.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A new type of LNG vaporizer assembly, characterized by: Including composition analyzer, refrigerant buffer tank, LNG vaporizer group; The LNG vaporizer group is connected to an LNG feed pipeline; an LNG feed valve is provided on the LNG feed pipeline; the sampling point of the composition analyzer is located at the front end of the LNG feed valve; The liquid-phase refrigerant outlet of the LNG vaporizer group is connected to the refrigerant user group; the refrigerant user group is connected to the refrigerant buffer tank, and the refrigerant buffer tank is connected to the gas-phase refrigerant inlet of the LNG vaporizer group.

2. A novel LNG vaporizer assembly according to claim 1, characterized in that: The LNG vaporizer group includes a heavy LNG vaporizer and a light LNG vaporizer; The heavy LNG inlet of the heavy LNG vaporizer and the light LNG inlet of the light LNG vaporizer are connected to an LNG feed pipeline; The LNG feed valve is connected to the heavy LNG inlet of the heavy LNG vaporizer or the light LNG inlet of the light LNG vaporizer respectively; The first liquid-phase refrigerant outlet located at the light LNG vaporizer and the second liquid-phase refrigerant outlet located at the heavy LNG vaporizer are respectively connected to the refrigerant user groups; The refrigerant buffer tank is respectively connected to a first gas-phase refrigerant inlet on the light LNG vaporizer and a second gas-phase refrigerant inlet on the heavy LNG vaporizer.

3. A novel LNG vaporizer assembly according to claim 2, characterized in that: It also includes LNG separation tanks; The liquid phase outlet of the LNG separation tank is connected to the LNG feed pipeline; the liquid phase outlet of the LNG separation tank is provided with an LNG pump; An LNG gas delivery pipe is provided on the top of the LNG separation tank; The LNG separation tank is connected to the light LNG outlet of the light LNG vaporizer and the heavy LNG outlet of the heavy LNG vaporizer respectively.

4. A novel LNG vaporizer assembly according to claim 2, characterized in that: It also includes a refrigerant storage tank, which is respectively connected to a first liquid-phase refrigerant outlet located at the light LNG vaporizer, a second liquid-phase refrigerant outlet located at the heavy LNG vaporizer, and a refrigerant user group.

5. The novel LNG vaporizer assembly according to claim 1, characterized in that: The detection signal of the component analyzer is used to control the opening and closing state of the LNG feed valve.

6. The novel LNG vaporizer assembly according to claim 4, characterized in that: A refrigerant pump is provided between the refrigerant storage tank and the refrigerant user group; a start-up refrigerant inlet is provided on the refrigerant storage tank for connecting the start-up refrigerant pipeline; The refrigerant pump is connected to the refrigerant user group through a circulating liquid-phase refrigerant pipe, and the refrigerant user group is connected to the refrigerant buffer tank through a circulating gas-phase refrigerant pipe; And / or, it also includes a start-up vaporizer, one end of the start-up vaporizer is connected to the refrigerant pump, and the other end is connected to the refrigerant buffer tank; The refrigerant user group is connected in parallel with the start-up vaporizer; And / or, the refrigerant buffer tank is connected to the light LNG vaporizer and the heavy LNG vaporizer respectively through refrigerant valves; And / or, the detection signal of the component analyzer is used to control the opening and closing state of the refrigerant valve; and / or, when the composition analyzer detects that the Cl content of the LNG feedstock is greater than 95%, the LNG feed valve is opened to the light LNG inlet connected to the shell side of the light LNG vaporizer, and simultaneously, the refrigerant valve is opened to the first gas-phase refrigerant inlet connected to the tube side of the light LNG vaporizer; When the composition analyzer detects that the C1 content of the LNG raw material is less than or equal to 95%, the LNG feed valve is connected to the heavy LNG inlet connected to the heavy LNG vaporizer tube side, and at the same time, the refrigerant valve is connected to the second gas phase refrigerant inlet connected to the heavy LNG vaporizer shell side; And / or, if the processing capacity of LNG raw materials increases, the light LNG vaporizer and the heavy LNG vaporizer are operated simultaneously.

7. The novel LNG vaporizer assembly according to claim 2, characterized in that: The light LNG vaporizer includes a light LNG shell and a light LNG tube bundle. A number of U-shaped heat exchange tube bundles are arranged in the light LNG shell. The U-shaped heat exchange tubes are arranged horizontally in the light LNG shell. The top of the light LNG shell is provided with a light LNG outlet connected to the shell side of the light LNG vaporizer; the LNG raw material exchanges heat with the refrigerant in the tube side in the shell side of the light LNG vaporizer.

8. The novel LNG vaporizer assembly according to claim 7, characterized in that: A first gas-phase refrigerant inlet is provided at the upper portion of the pipe box of the light LNG vaporizer, and a first liquid-phase refrigerant outlet is provided at the lower portion of the pipe box of the light LNG vaporizer. The first gas-phase refrigerant inlet is connected to the first liquid-phase refrigerant outlet through the pipe box, the tube sheet and the U-shaped heat exchange tube bundle; The light LNG shell of the light LNG vaporizer includes a first-stage shell, a transition-stage shell, and a second-stage shell. The first-stage shell and the second-stage shell are connected by the transition-stage shell. The diameter of the first-stage shell is smaller than the diameter of the second-stage shell. The lowermost end of the first-stage shell is flush with the lowermost end of the second-stage shell. The inlet end of the U-shaped heat exchange tube is located on one side of the first shell; the U-shaped end of the U-shaped heat exchange tube is located in the second shell; A plurality of staggered single-bow baffles and a first support plate are provided between the light LNG tube bundle and the light LNG shell; An overflow weir is also provided in the light LNG shell, and the overflow weir is set near the outer end of the U-bend; The light LNG vaporizer has a light LNG inlet at the bottom of the light LNG shell, a light LNG outlet at the top of the light LNG shell, and a light LNG heavy component liquid phase outlet at the bottom of the light LNG shell; the light LNG inlet is located on the side of the overflow weir close to the pipe box, and the light LNG heavy component liquid phase outlet is located on the side of the overflow weir away from the pipe box; The light LNG outlet is located at the top of the second-stage shell.

9. The novel LNG vaporizer assembly according to claim 2, characterized in that: The heavy LNG vaporizer includes a heavy LNG shell and a heavy LNG tube bundle; Several U-shaped heat exchange tube bundles are provided in the heavy LNG shell, and the U-shaped heat exchange tubes are arranged transversely in the heavy LNG shell; The gas phase refrigerant exchanges heat with the LNG raw material located in the tube side of the heavy LNG vaporizer in the shell side of the heavy LNG shell.

10. The novel LNG vaporizer assembly according to claim 9, characterized in that: A heavy LNG inlet is provided at the bottom of the pipe box of the heavy LNG vaporizer, and a heavy LNG outlet is provided at the top of the pipe box of the heavy LNG vaporizer. The heavy LNG inlet and the heavy LNG outlet are connected through the pipe box, tube sheet and U-shaped heat exchange tube bundle.

11. The novel LNG vaporizer assembly according to claim 10, characterized in that: An external guide collar is provided on the shell side inlet of the heavy LNG vaporizer, and 2 to 3 air inlet grooves are evenly opened on the external guide collar. The gas phase refrigerant is connected to the cavity between the shell side of the heavy LNG vaporizer through the air inlet grooves. A second liquid-phase refrigerant outlet is provided at the bottom of the heavy LNG shell of the heavy LNG vaporizer; The heavy LNG vaporizer has a heavy LNG shell with a number of single-bow or double-bow baffles, and the baffles have a number of through holes supporting the U-shaped heat exchange tube bundles; The second gas-phase refrigerant inlet of the heavy LNG vaporizer is connected to the refrigerant buffer tank, and the second liquid-phase refrigerant outlet of the heavy LNG vaporizer is connected to the refrigerant storage tank.

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