Novel LNG vaporizer assembly

Abstract

A novel LNG vaporizer assembly, comprising a composition analyzer (3), a refrigerant buffer tank (10), and an LNG vaporizer unit. The LNG vaporizer unit is connected to LNG feed piping; an LNG feed valve (4) is provided on the LNG feed piping; a sampling point of the composition analyzer (3) is located at the front end of the LNG feed valve (4); liquid-phase refrigerant outlets (22, 37) of the LNG vaporizer unit are connected to a refrigerant user unit (12); the refrigerant user unit (12) is connected to the refrigerant buffer tank (10), and the refrigerant buffer tank (10) is connected to gas-phase refrigerant inlets (21, 36) of the LNG vaporizer unit. The LNG vaporizer assembly features a simple structure and low investment, and the LNG vaporizer assembly is suitable for LNG feedstock of various compositions, and operates safely and stably. By using a special working medium such as propylene or ethylene as a working medium for recovering LNG cold energy, a substantial amount of high-grade, multi-temperature-level cold energy can be provided for other devices after a substantial amount of LNG cold energy is recovered, thereby greatly reducing the energy consumption of the device and achieving the recycling of resources.

Description

A novel LNG vaporizer assembly Technical Field

[0001] This invention belongs to the field of petrochemical technology, and in particular relates to a novel LNG vaporizer assembly with a special working medium. Specifically, it relates to a novel LNG vaporizer assembly that realizes the vaporization of LNG while also recovering and utilizing the cold energy of LNG. Background Technology

[0002] LNG vaporizers are heat exchangers specifically designed for the vaporization of liquefied natural gas. They are primarily used in large coastal LNG receiving terminals, LNG liquefaction plants, LNG vaporization stations, and LNG refueling stations, and are key equipment for achieving vaporization. Depending on the properties and composition of LNG, LNG vaporizers require different structural designs. Common types of LNG vaporizers include open-frame vaporizers (ORV), submerged combustion vaporizers (SCV), intermediate fluid vaporizers (IFV), ambient air vaporizers, forced draft vaporizers, hot air heated vaporizers, vacuum steam vaporizers (VSV), intermediate medium ambient air vaporizers, and hot water bath vaporizers. These vaporizers have complex structures; some use aluminum alloy heat transfer tubes with internal star-shaped cross-sections and helical rods, and external fins; others are spiral wound heat exchangers. Therefore, their manufacturing structure is complex, and the equipment cost is high. Furthermore, none of these vaporizers are universally applicable to all LNG feedstock compositions and offer high efficiency.

[0003] On the other hand, LNG vaporizers are classified according to the heat medium used for LNG vaporization. Common LNG vaporization heat media include air, river water or seawater, natural gas combustion, electric heating, and factory waste heat. These heat media are only used to achieve LNG vaporization, but the cold energy of LNG is not recovered and reused, and this cold energy is wasted. Low-temperature LNG vaporization releases a large amount of cold energy, approximately 850 KJ / kg. This cold energy should be fully recovered and utilized to achieve the goals of energy conservation and improved economic efficiency.

[0004] In traditional petroleum and chemical plants, ethylene compressors are commonly used in olefin separation units. Propylene compressors provide cooling energy for pre-cooling the feedstock or condensing the overhead material in the separation system. Generally, propylene cycle refrigeration compressors 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 substances, some units may require even lower-temperature ethylene refrigeration compressors to provide the separation energy. The compressor system is a key piece of equipment for the stable operation of the olefin separation unit. It is also a core piece of equipment with a relatively large investment, long manufacturing cycle, and high safety requirements, making it a crucial element in the overall process design; however, its complexity and high investment cost are significant factors.

[0005] Therefore, it is of great significance to develop a new type of LNG vaporizer assembly that is highly adaptable to LNG feedstock and has low equipment investment costs. Summary of the Invention

[0006] In view of this, the present invention aims to provide a novel LNG vaporizer assembly that uses a special working fluid, such as ethylene or propylene, to solve at least one of the problems in the background art described above.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A novel LNG vaporizer assembly includes a composition analyzer, a refrigerant buffer tank, and an LNG vaporizer unit;

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

[0010] The liquid 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 gaseous refrigerant inlet of the LNG vaporizer group.

[0011] Preferably, the LNG vaporizer assembly 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 LNG feed pipelines;

[0013] The LNG feed valves are respectively connected to the heavy LNG inlet of the heavy LNG vaporizer or the light LNG inlet of the light LNG vaporizer.

[0014] The first liquid refrigerant outlet in the light LNG vaporizer and the second liquid refrigerant outlet in the heavy LNG vaporizer are respectively connected to the refrigerant user group;

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

[0016] The LNG vaporizer assembly of this invention has a simple structure and low investment. It is applicable to LNG feedstocks of various compositions and operates safely and stably. By selecting propylene or ethylene as the working fluid for recovering LNG cold energy, a large amount of recovered LNG cold energy can provide other units with a large amount of high-grade, multi-level cooling capacity, significantly reducing the unit's energy consumption and achieving resource recycling.

[0017] Preferably, the LNG vaporizer assembly further includes an LNG separator tank;

[0018] The liquid phase outlet of the LNG separator is connected to the LNG feed pipeline; the liquid phase outlet of the LNG separator is equipped with an LNG pump.

[0019] The top of the LNG separator is equipped with an LNG gas outlet pipe;

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

[0021] Preferably, the LNG vaporizer assembly further includes a refrigerant storage tank, which is connected to the first liquid refrigerant outlet of the light LNG vaporizer, the second liquid refrigerant outlet of the heavy LNG vaporizer, and the refrigerant user group.

[0022] Preferably, the detection signals from the analyzer are used to control the opening and closing status of the LNG feed valve.

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

[0024] The refrigerant pump is connected to the refrigerant user group through a circulating liquid refrigerant line, and the refrigerant user group is connected to the refrigerant buffer tank through a circulating gaseous refrigerant line.

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

[0028] And / or, the detection signals that make up the analyzer are used to control the opening and closing state of the refrigerant valve.

[0029] And / or, when the composition analyzer detects that the C1 content of the LNG feedstock is greater than 95%, the LNG feed valve is connected to the light LNG inlet connected to the shell side of the light LNG vaporizer, and at the same time, the refrigerant valve is connected 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 feedstock is less than or equal to 95%, the LNG feed valve is connected to the heavy LNG inlet of the tube side of the heavy LNG vaporizer, and at the same time, the refrigerant valve is connected to the second gas phase refrigerant inlet of the shell side of the heavy LNG vaporizer.

[0031] And / or, if the LNG feedstock throughput increases, the light LNG vaporizer and the heavy LNG vaporizer operate simultaneously.

[0032] Furthermore, the light LNG vaporizer includes a light LNG shell and a light LNG tube bundle. Several U-shaped heat exchange tube bundles are provided inside the light LNG shell. The heat exchange tubes are arranged laterally inside the light LNG shell. The top of the light LNG shell is provided with a light LNG outlet that connects to the shell side of the light LNG vaporizer. The LNG feedstock exchanges heat with the gaseous refrigerant located in the tube side of the light LNG vaporizer in the shell side.

[0033] Furthermore, the upper part of the tube box of the light LNG vaporizer is provided with a first gaseous refrigerant inlet, and the lower part of the tube box of the light LNG vaporizer is provided with a first liquid refrigerant outlet. The first gaseous refrigerant inlet is connected to the first liquid refrigerant outlet through the tube box, tube sheet and U-shaped heat exchange tube bundle.

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

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

[0036] Several staggered single-bow baffles and a first support plate are provided between the light LNG tube bundle and the light LNG shell. In addition, an overflow weir is also provided inside the light LNG shell, which is located on the side near the outer end of the U-shaped bend.

[0037] Furthermore, 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 phase liquid phase outlet at the bottom of the light LNG shell; the light LNG inlet is located on the side close to the gaseous refrigerant inlet and outlet, and the light LNG gaseous outlet is located on the side away from the refrigerant inlet and outlet.

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

[0039] The light LNG outlet is located at the top of the two-stage shell; the first gaseous refrigerant inlet of the light LNG vaporizer is connected to the refrigerant buffer tank, the first liquid 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 after the refrigerant pump delivers the liquid refrigerant to the user of the petrochemical separation unit, the gaseous 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] The heavy LNG shell is equipped with several U-shaped heat exchange tube bundles, which are arranged laterally inside the heavy LNG shell;

[0042] The gaseous refrigerant exchanges heat with the LNG feedstock located in the tube side of the heavy LNG vaporizer within the shell side of the heavy LNG shell.

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

[0044] The shell-side inlet of the heavy LNG vaporizer is provided with an outer guide ring, and 2 to 3 air inlet slots are evenly opened on the outer guide ring. The gaseous refrigerant is connected to the cavity between the shell and the heavy LNG vaporizer through the air inlet slots.

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

[0046] The heavy LNG vaporizer has several single or double bow baffles inside the heavy LNG shell, and several through holes on the baffles support the U-shaped heat exchange tube bundle.

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

[0048] By adopting the novel LNG vaporizer assembly described in this invention and using special working fluids such as ethylene or propylene as refrigerants, 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 device described above, and based on the design optimization calculations of the light hydrocarbon recovery unit, it can be concluded 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 existing technologies, the novel LNG vaporizer assembly described in this invention has the following advantages:

[0051] It boasts advantages such as simple process, low energy consumption, low investment, and stable operation. Based on the optimized design results of the light hydrocarbon recovery unit, the adoption of the novel LNG vaporizer assembly described in this invention significantly reduces power consumption during unit operation, while also saving circulating water consumption and lowering equipment investment costs. Attached Figure Description

[0052] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0053] Figure 1 is an overall schematic diagram of a novel LNG vaporizer assembly according to Embodiment 1 of the present invention;

[0054] Figure 2 is a schematic diagram of the light LNG vaporizer described in Embodiment 3 of the present invention;

[0055] Figure 3 is a schematic diagram of the heavy LNG vaporizer described in Embodiment 4 of the present invention;

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

[0057] Explanation of reference numerals in the attached figures:

[0058] 1. LNG separator; 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 feedstock from tank farm; 14. LNG gas delivery pipeline; 15. Start-up refrigerant pipeline; 16. Circulating liquid phase refrigerant pipeline; 17. Circulating gas phase refrigerant pipeline; 19. Light LNG tubing bundle; 20. Light LNG shell; 21. 21. First gaseous refrigerant inlet; 22. First liquid refrigerant outlet; 23. Transition section shell; 24. Single-bow baffle; 25. First support plate; 26. Light LNG inlet; 27. Light LNG outlet; 28. Overflow weir; 29. ​​Heavy LNG liquid phase outlet; 30. Heavy LNG tube bundle; 31. Heavy LNG shell; 32. Heavy LNG inlet; 33. Heavy LNG outlet; 34. External guide ring; 35. Inlet tank; 36. Second gaseous refrigerant inlet; 37. Second liquid refrigerant outlet; 38. Baffle of heavy LNG vaporizer. Detailed Implementation

[0059] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0060] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Example 1

[0061] As shown in Figure 1, this 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.

[0062] 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.

[0063] The LNG feed pipeline is equipped with 4 LNG feed valves, 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.

[0064] The sampling point of the composition analyzer 3 is located at the front end of the LNG feed valve 4;

[0065] The first liquid refrigerant outlet 22 located in the light LNG vaporizer 6 and the second liquid refrigerant outlet 37 located in the heavy LNG vaporizer 5 are respectively connected to the refrigerant user group 12;

[0066] The refrigerant user group 12 is connected to the refrigerant buffer tank 10, which is connected to the first vapor phase refrigerant inlet 21 on the light LNG vaporizer 6 and the second vapor phase refrigerant inlet 36 on the heavy LNG vaporizer 5.

[0067] LNG feedstock from the boundary area is connected via LNG feed lines to either the tube side of the heavy LNG vaporizer 55 or the shell side of the light LNG vaporizer 66. A composition analyzer 3, located on the LNG feed line, is used to detect the composition of the LNG feedstock. The detection signal controls the opening and closing of the LNG feed valve 4, feeding the LNG into either the light LNG vaporizer 6 or the heavy LNG vaporizer 5. The LNG feed valve 4 can be a three-way valve. After exchanging heat with the LNG feedstock in the heavy LNG vaporizer 5 or the light LNG vaporizer 6, the vaporized refrigerant becomes liquid refrigerant. The refrigerant uses a special working fluid, propylene or ethylene. After supplying cooling to the refrigerant user group 12, the liquid refrigerant enters the refrigerant buffer tank 10, and then re-enters the light LNG vaporizer 6 or the heavy LNG vaporizer 5. Example 2

[0068] Based on Example 1, this embodiment of the novel LNG vaporizer assembly further includes an LNG separator tank 1;

[0069] The liquid phase outlet of LNG separator 1 is connected to the LNG feed pipeline; the liquid phase outlet of LNG separator 1 is equipped with an LNG pump 2;

[0070] The top of the LNG separator 1 is equipped with an LNG gas outlet pipe 14;

[0071] The LNG separator 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.

[0072] LNG feedstock is vaporized by either a light LNG vaporizer or a heavy LNG vaporizer and then sent to LNG separator 1. After separation in LNG separator 1, the gaseous LNG is sent out as a product, while the liquid LNG is pressurized by LNG pump 2 and then fed into the LNG feedstock main for recycling. Simultaneously, liquid start-up refrigerant, which is propylene or ethylene, from the boundary area is filled into refrigerant storage tank 8 in one go. During the start-up phase, it is sent to start-up vaporizer 11 by refrigerant pump 9. The vaporized refrigerant is sent to the shell side of heavy LNG vaporizer 5 or the tube side of light LNG vaporizer 6 through refrigerant valve 7. The condensed liquid refrigerant flows back to refrigerant storage tank 8. After the system establishes pressure balance, start-up vaporizer 11 is shut off. The refrigerant in refrigerant storage tank 8 is sent to the nearby refrigerant user group 12 by refrigerant pump 9. After being vaporized in refrigerant user group 12, it is sent to refrigerant buffer tank 10, and the above cycle is repeated to provide a continuous supply of cooling energy to refrigerant user group 12. LNG feed valve 4 and refrigerant valve 7 simultaneously receive signals from composition analyzer 3. Specifically, when the C1 content of LNG feedstock is less than or equal to 95%, LNG feed valve 4 and refrigerant valve 7 simultaneously open the valve passage leading to light LNG vaporizer 6; when the C1 content of LNG feedstock is greater than 95%, LNG feed valve 4 and refrigerant valve 7 simultaneously open the valve passage leading to heavy LNG vaporizer 5.

[0073] In practical applications, 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 volume is large and peak usage is expected, the three-way valves of both the light LNG vaporizer 6 and the heavy LNG vaporizer 5 can be opened simultaneously to activate the LNG vaporizer assemblies and increase the processing capacity. When the C1 content in the LNG feedstock is less than or equal to 95%, the material composition is complex and the boiling range is wide, and it is defined as heavy LNG. In this case, the material enters the heavy LNG vaporizer 5 through the three-way valve. When the C1 content in the LNG feedstock is greater than 95%, the material composition is simple and the boiling range is small, and it is defined as light LNG. In this case, the material switches to the light LNG vaporizer 6 through the three-way valve. Example 3

[0074] This embodiment is based on embodiment 2, as shown in Figure 2;

[0075] 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, and several light LNG tube bundles 19 are arranged laterally inside the light LNG shell 20. The gaseous refrigerant exchanges heat with the light LNG feedstock located in the shell side within the heat exchange tube bundle 19 of the light LNG vaporizer. The upper part of the tube bundle of the light LNG vaporizer is provided with a first gaseous refrigerant inlet 21, and the lower part of the tube bundle of the light LNG vaporizer is provided with a first liquid refrigerant outlet 22. The first gaseous refrigerant inlet 21 is connected to the tube bundle of the light LNG vaporizer through the tube bundle and tube sheet, and the first liquid refrigerant outlet 22 is connected to the tube bundle of the light LNG vaporizer through the tube bundle and tube sheet. The middle part of the light LNG shell 20 is provided with a transition section shell 23. Several staggered single-bow baffles 24 and a first support plate 25 are provided between the light LNG shell 20 and the light LNG tube bundle 19. An overflow weir 28 is provided inside the light LNG shell 20, and the overflow weir 28 is located on the side away from the first liquid refrigerant outlet. A single-bow baffle 24 is located on the side near the refrigerant outlet and on the side of the transition section 23; the single-bow baffle 24 and the first support plate 25 are provided with several through holes; the bottom of the light LNG shell 20 is provided with a light LNG inlet 26, and the upper part of the light LNG shell 20 is provided with a light LNG outlet 27; the light LNG inlet 26 is located on the side near the refrigerant outlet, the light LNG outlet 27 is located on the side away from the refrigerant outlet, and the heavy component liquid phase outlet 29 is located at the bottom of the light LNG shell 20; the light LNG outlet 27 is located on one side of the overflow weir 28, and the heavy component liquid phase outlet 29 is located on the other side of the overflow weir 28; the first gaseous refrigerant inlet 21 of the light LNG vaporizer 6 is connected to the refrigerant buffer tank 10 through the pipeline of the refrigerant valve 7, and the first liquid 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 gaseous refrigerant after being vaporized in the refrigerant user group 12 is circulated to the refrigerant buffer tank 10, thus cyclically utilizing the cold energy of LNG. Example 4

[0076] This embodiment is based on embodiment 2, as shown in Figures 3 and 4;

[0077] The heavy LNG vaporizer 5 includes a heavy LNG shell 30 and a heavy LNG tube bundle 31. The heavy LNG shell 30 is provided with several U-shaped heat exchange tubes, which are arranged laterally inside the heavy LNG vaporizer shell 30. The heavy LNG tube bundle 31 is arranged inside the heavy LNG vaporizer shell 30. The gaseous refrigerant exchanges heat with the heavy LNG feedstock located in the tube bundle in the shell side of the heavy LNG vaporizer. The heavy LNG vaporizer 5 has a heavy LNG inlet 32 ​​at the bottom of its tube box and a heavy LNG outlet 33 at the top of its tube box. The heavy LNG inlet 32 ​​is connected to the heat exchange tube bundle through the tube box and tube sheet, and the heavy LNG outlet 33 is also connected to the heat exchange tube bundle through the tube box and tube sheet. The heavy LNG shell 30 is provided with an outer flow guide ring 34. Two to three inlet grooves 35 are evenly arranged on the outer flow guide ring 34 to facilitate the uniform entry of a large amount of gaseous refrigerant into the second gaseous refrigerant inlet 36 of the shell side of the heavy LNG vaporizer 5. The gaseous refrigerant enters the heavy LNG shell 30 through the inlet groove 35, flows through the baffle plate 38 with several through holes, and then flows to the second liquid refrigerant outlet 37 and is sent to the refrigerant storage tank 8. It is then sent to the refrigerant user group 12 by the refrigerant pump 9. The gaseous refrigerant that is vaporized in the refrigerant user group 12 is circulated to the refrigerant buffer tank 10, thus cyclically utilizing the cold energy of LNG.

[0078] LNG from the boundary area undergoes indirect heat exchange with cryogenic special working fluids in the LNG vaporizer group. The condensed propylene or ethylene is pressurized by a cryogenic pump and then divided into two or more stages according to the separation temperature requirements and properties of the refrigerant user group, generally at least two stages. The stage above 5°C can switch the circulating water user in the original separation unit to the refrigerant user, which not only improves the heat exchange efficiency but also greatly saves the consumption of circulating water. The other refrigerant stages can be divided into refrigerant working fluids of -8°C, -20°C, -40°C, -60°C, or even -80°C according to the actual needs of the unit users. This not only realizes the graded utilization of energy levels but also reduces the investment cost of cryogenic equipment and improves the heat exchange efficiency of the equipment.

[0079] Example of a project in a certain area

[0080] When the refrigerant is ethylene and the composition analyzer detects that the LNG feedstock is the heavy LNG shown in Table 1, simulations show that the subcooling load is relatively large, accounting for 50.71% of the total heat load. Therefore, under this condition, the design of the subcooling section and the maximum recovery of cooling capacity need to be fully considered. In this application, to save investment and space, the heavy LNG feedstock enters the heavy LNG vaporizer. The specific simplified diagram of the heavy LNG vaporizer equipment design is shown in Figures 3 and 4. The tube bundle length of the heavy LNG heat exchange tube is 7.5 meters, and the tube bundle diameter is 1.8 meters (the tube bundle diameter includes the sum of the tube diameter and the tube center distance). The shell side is uniformly arranged with single-arch baffles with an opening ratio of about 30% to 40%. In addition, due to the large gas volume at the shell-side inlet, in order to avoid the reduction in the number of pipes caused by the large opening of the shell-side cylinder of the heavy LNG vaporizer, and to prevent pipe vibration caused by excessive gas flow velocity, this design sets a special flow guiding device at the shell-side inlet of the heavy LNG vaporizer. The outer flow guiding ring 34 is 1.4 meters wide and 0.5 meters high, and 2 to 3 slots are symmetrically opened on the flow guiding device to ensure stable fluid flow and reasonable structure of the heavy LNG vaporizer.

[0081] When the refrigerant is ethylene and the composition analyzer detects that the LNG feedstock is light LNG as shown in Table 1, the material composition is simple and easy to vaporize. At this time, the light LNG feedstock enters the light LNG vaporizer. The specific simplified diagram of the light LNG vaporizer equipment design is shown in Figure 2. The tube bundle length of the heat exchange tubes of the light LNG vaporizer is 7.5 meters, the tube 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 it enters the vaporization section with a shell-side flow length of 5.5 meters. The vaporization section is evenly arranged with the first support plate 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 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.

[0082] Table 1 Light / Heavy LNG Feedstock Composition Table

[0083]

[0084] Note: C3+ is 0.9% iC4+, 0.9% nC4+, 0.1% iC5+, and 0.1% nC5+.

[0085] Using the above-mentioned device of the present invention, and based on the design optimization calculations of the light hydrocarbon recovery device, it can be concluded that, compared with the traditional propylene compressor refrigeration, the equipment cost of the above-mentioned device of the present invention can be reduced by more than 20%.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel LNG vaporizer assembly, characterized in that: Includes a composition analyzer, a refrigerant buffer tank, and an LNG vaporizer assembly; The LNG vaporizer assembly is connected to an LNG feed pipeline; an LNG feed valve is installed on the LNG feed pipeline; the sampling point of the component analyzer is located at the front end of the LNG feed valve; The liquid 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 gaseous refrigerant inlet of the LNG vaporizer group.

2. The novel LNG vaporizer assembly according to claim 1, characterized in that: The LNG vaporizer assembly 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 LNG feed pipelines; The LNG feed valves are respectively connected to the heavy LNG inlet of the heavy LNG vaporizer or the light LNG inlet of the light LNG vaporizer. The first liquid refrigerant outlet in the light LNG vaporizer and the second liquid refrigerant outlet in the heavy LNG vaporizer are respectively connected to the refrigerant user group; The refrigerant buffer tank is connected to a first vapor-phase refrigerant inlet on the light LNG vaporizer and a second vapor-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 separator tanks; The liquid phase outlet of the LNG separator is connected to the LNG feed pipeline; the liquid phase outlet of the LNG separator is equipped with an LNG pump. The top of the LNG separator is equipped with an LNG gas outlet pipe; The LNG separator is connected to the light LNG outlet of the light LNG vaporizer and the heavy LNG outlet of the heavy LNG vaporizer.

4. A novel LNG vaporizer assembly according to claim 2, characterized in that: It also includes refrigerant storage tanks, which are respectively connected to the first liquid refrigerant outlet of the light LNG vaporizer, the second liquid refrigerant outlet of the heavy LNG vaporizer, and the refrigerant user group.

5. A novel LNG vaporizer assembly according to claim 1, characterized in that: The detection signals from the analyzer are used to control the opening and closing status of the LNG feed valve.

6. A novel LNG vaporizer assembly according to claim 4, characterized in that: A refrigerant pump is installed between the refrigerant storage tank and the refrigerant user group; the refrigerant storage tank is equipped with a start-up refrigerant inlet for connecting to the start-up refrigerant pipeline; The refrigerant pump is connected to the refrigerant user group through a circulating liquid refrigerant line, and the refrigerant user group is connected to the refrigerant buffer tank through a circulating gaseous refrigerant line. And / or, it also includes a start-up vaporizer, one end of which is connected to a refrigerant pump and the other end to a 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 via refrigerant valves; And / or, the detection signals that make up the analyzer are used to control the opening and closing state of the refrigerant valve; And / or, when the composition analyzer detects that the C1 content of the LNG feedstock is greater than 95%, the LNG feed valve is connected to the light LNG inlet connected to the shell side of the light LNG vaporizer, and at the same time, the refrigerant valve is connected 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 feedstock is less than or equal to 95%, the LNG feed valve is connected to the heavy LNG inlet of the tube side of the heavy LNG vaporizer, and at the same time, the refrigerant valve is connected to the second gas phase refrigerant inlet of the shell side of the heavy LNG vaporizer. And / or, if the LNG feedstock throughput increases, the light LNG vaporizer and the heavy LNG vaporizer operate simultaneously.

7. A novel LNG vaporizer assembly according to claim 2, characterized in that: The light LNG vaporizer includes a light LNG shell and light LNG tube bundles. Several U-shaped heat exchange tube bundles are installed inside the light LNG shell. The U-shaped heat exchange tubes are arranged laterally inside the light LNG shell. The top of the light LNG shell is provided with a light LNG outlet that connects to the shell side of the light LNG vaporizer. The LNG feedstock exchanges heat with the refrigerant located in the tube side of the light LNG vaporizer in the shell side.

8. A novel LNG vaporizer assembly according to claim 7, characterized in that: The upper part of the tube box of the light LNG vaporizer is provided with a first gaseous refrigerant inlet, and the lower part of the tube box of the light LNG vaporizer is provided with a first liquid refrigerant outlet. The first gaseous refrigerant inlet is connected to the first liquid refrigerant outlet through the tube box, tube sheet and U-shaped heat exchange tube bundle. The light LNG vaporizer's light LNG shell includes a first-stage shell, a transition shell, and a second-stage shell, with the first-stage shell and the second-stage shell connected by the transition shell; the diameter of the first-stage shell is smaller than the diameter of the second-stage shell; the bottom end of the first-stage shell is flush with the bottom end of the second-stage shell; The inlet end of the U-shaped heat exchange tube is located on one side of a first-section shell; the U-shaped end of the U-shaped heat exchange tube is located inside the second-section shell. Several 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 inside the light LNG shell, and the overflow weir is located on the side 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 recombinant liquid phase outlet at the bottom of the light LNG shell; the light LNG inlet is located on the side of the overflow weir closer to the pipe box, and the light LNG recombinant 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 two-stage shell.

9. A novel LNG vaporizer assembly according to claim 2, characterized in that: A heavy LNG vaporizer includes a heavy LNG shell and a heavy LNG tubing bundle; The heavy LNG shell is equipped with several U-shaped heat exchange tube bundles, which are arranged laterally inside the heavy LNG shell; The gaseous refrigerant exchanges heat with the LNG feedstock located in the tube side of the heavy LNG vaporizer within the shell side of the heavy LNG shell.

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

11. A novel LNG vaporizer assembly according to claim 10, characterized in that: The shell-side inlet of the heavy LNG vaporizer is provided with an outer guide ring, and 2 to 3 air inlet slots are evenly opened on the outer guide ring. The gaseous refrigerant is connected to the cavity between the shell and the heavy LNG vaporizer through the air inlet slots. The heavy LNG vaporizer has a second liquid refrigerant outlet at the bottom of the heavy LNG shell; The heavy LNG vaporizer has several single or double bow baffles inside the heavy LNG shell, and several through holes on the baffles support the U-shaped heat exchange tube bundle. The second gaseous refrigerant inlet of the heavy LNG vaporizer is connected to the refrigerant buffer tank, and the second liquid refrigerant outlet of the heavy LNG vaporizer is connected to the refrigerant storage tank.

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