阅读说明：本技术 一种bog再冷凝器与bog再冷凝方法 (BOG recondensor and BOG recondensation method ) 是由 王以斌 郭维军 曾波 于 2019-03-25 设计创作，主要内容包括：本发明公开了一种BOG再冷凝器与BOG再冷凝方法。BOG再冷凝器设有外壳(1),外壳内自上而下设有顶部缓冲挡板(7)、LNG喷射板(9)、气液分布板(10)、填料顶板(11)、填料底板(12)和底部缓冲挡板(8),还设有垂直的液氮上升管(13)；填料(14)设于填料顶板与填料底板之间。外壳上设有BOG入口(3)、LNG入口(2)、LNG出口(4)、液氮入口(5)和液氮出口(6)。本发明的BOG再冷凝方法使用上述的BOG再冷凝器,采用液氮作为辅助介质,与LNG共同冷凝BOG使BOG液化。本发明主要用于LNG接收站,对BOG进行再冷凝回收。(The invention discloses a BOG recondenser and a BOG recondensing method. The BOG recondenser is provided with a shell (1), a top buffer baffle (7), an LNG injection plate (9), a gas-liquid distribution plate (10), a filler top plate (11), a filler bottom plate (12) and a bottom buffer baffle (8) are arranged in the shell from top to bottom, and a vertical liquid nitrogen ascending pipe (13) is further arranged in the shell; the packing (14) is arranged between the packing top plate and the packing bottom plate. The shell is provided with a BOG inlet (3), an LNG inlet (2), an LNG outlet (4), a liquid nitrogen inlet (5) and a liquid nitrogen outlet (6). The BOG recondensation method of the invention uses the BOG recondensor, adopts liquid nitrogen as an auxiliary medium, and condenses BOG together with LNG to liquefy BOG. The invention is mainly used for the LNG receiving station to carry out recondensation and recovery on the BOG.)

1. The utility model provides a BOG recondenser, is equipped with shell (1), and shell (1) is equipped with filler (14) including vertical cylinder barrel and top head and bottom head inside, is equipped with BOG entry (3), LNG entry (2) and LNG export (4) on shell (1), its characterized in that: a top buffer baffle (7), an LNG injection plate (9), a gas-liquid distribution plate (10), a filler top plate (11), a filler bottom plate (12), a bottom buffer baffle (8) and a vertical liquid nitrogen riser (13) are arranged in the shell (1) from top to bottom, LNG injection holes (901) are arranged on the LNG injection plate (9), gas-liquid distribution holes (101) are arranged on the gas-liquid distribution plate (10), the filler (14) is arranged between the filler top plate (11) and the filler bottom plate (12), the liquid nitrogen riser (13) penetrates through the LNG injection plate (9), the gas-liquid distribution plate (10), the filler top plate (11), the filler (14) and the filler bottom plate (12), the bottom of the liquid nitrogen riser (13) is arranged on the bottom buffer baffle (8), the top is arranged on the top buffer baffle (7), and in the shell (1), the space above the top buffer baffle (7) is a top liquid nitrogen buffer space (15, the space between the top buffer baffle (7), the LNG injection plate (9) and the liquid nitrogen ascending pipe (13) is an LNG buffer space (17), the space between the LNG injection plate (9), the gas-liquid distribution plate (10) and the liquid nitrogen ascending pipe (13) is a gas-liquid mixing space (18), the space between the packing bottom plate (12), the bottom buffer baffle (8) and the liquid nitrogen ascending pipe (13) is an LNG liquid phase space (19), the space below the bottom buffer baffle (8) is a bottom liquid nitrogen buffer space (16), the shell (1) is provided with a liquid nitrogen inlet (5) and a liquid nitrogen outlet (6), the bottoms of the liquid nitrogen inlet (5) and the liquid nitrogen ascending pipe (13) are communicated with the bottom liquid nitrogen buffer space (16), the tops of the liquid nitrogen outlet (6) and the liquid nitrogen ascending pipe (13) are communicated with the top liquid nitrogen buffer space (15), the BOG inlet (3) is communicated with the gas-liquid mixing space (18), the LNG inlet (2) is communicated with the LNG buffer space (17), and the LNG outlet (4) is communicated with the LNG liquid phase space (19).

2. The BOG recondenser of claim 1, wherein: the axial lead of the shell (1) is provided with a liquid nitrogen ascending pipe (13), one circle or more than one circle of liquid nitrogen ascending pipes (13) are arranged around the liquid nitrogen ascending pipe (13), and the circle of liquid nitrogen ascending pipes (13) are distributed in a regular hexagon or in a circular shape on a horizontal plane vertical to the liquid nitrogen ascending pipes (13).

3. The BOG recondenser of claim 1, wherein: the LNG injection holes (901) formed in the LNG injection plate (9) are circular holes, the LNG injection plate (9) is distributed in a regular triangle or rectangular shape, the diameters of the LNG injection holes (901) are 5-10 mm, and the distance between every two adjacent LNG injection holes (901) is 2-3 times of the diameter of the LNG injection holes (901).

4. The BOG recondenser of claim 3, wherein: the gas-liquid distribution holes (101) formed in the gas-liquid distribution plate (10) are circular holes and are distributed on the gas-liquid distribution plate (10) in a regular triangle or rectangular shape, the diameters of the gas-liquid distribution holes (101) are 2-3 times of the diameters of the LNG injection holes (901), and the distance between every two adjacent gas-liquid distribution holes (101) is 2-3 times of the diameters of the gas-liquid distribution holes (101).

5. The BOG recondenser of claim 1, wherein: the BOG inlet (3) and the LNG inlet (2) are arranged at the upper part of the vertical cylindrical barrel of the shell (1), the LNG outlet (4) is arranged at the lower part of the vertical cylindrical barrel of the shell (1), the liquid nitrogen inlet (5) is arranged on the bottom end of the shell (1), and the liquid nitrogen outlet (6) is arranged on the top end of the shell (1).

6. A BOG recondenser according to any one of claims 1 to 5, wherein: the packing (14) is pall ring packing, Raschig ring packing or regular packing.

7. A BOG recondensation method is characterized in that the BOG recondensation method of claim 1 is adopted, liquid nitrogen for condensing BOG enters a liquid nitrogen buffer space (16) at the bottom from a liquid nitrogen inlet (5), then enters a liquid nitrogen riser (13) from the bottom of the liquid nitrogen riser (13) and flows upwards, LNG for condensing BOG enters an LNG buffer space (17) from an LNG inlet (2), then is sprayed downwards from an LNG spray hole (901) on an LNG spray plate (9) and enters a gas-liquid mixing space (18), BOG to be condensed enters the gas-liquid mixing space (18) from a BOG inlet (3) and is mixed with LNG in the gas-liquid mixing space (18), the mixed gas-liquid mixture flows downwards through gas-liquid distribution holes (101) on a gas-liquid distribution plate (10), enters a filler (14) through a filler top plate (11), is further contacted and mixed, and is in the gas-liquid mixing space (18) and the filler (14), under the action of LNG used for condensing BOG and liquid nitrogen in the liquid nitrogen ascending pipe (13), BOG is gradually condensed into liquid phase, the liquid phase flows downwards into an LNG liquid phase space (19) through a packing bottom plate (12), is further condensed by the liquid nitrogen in the liquid nitrogen ascending pipe (13) and then flows out of a BOG recondensor from an LNG outlet (4), and the liquid nitrogen in the liquid nitrogen ascending pipe (13) flows into a liquid nitrogen buffer space (15) from the top of the liquid nitrogen ascending pipe (13) and then flows out of the BOG recondensor from a liquid nitrogen outlet (6).

8. The method of claim 7, wherein: the temperature of liquid nitrogen for condensing BOG at the liquid nitrogen inlet (5) is-180 to-196 ℃, the temperature of LNG for condensing BOG at the LNG inlet 2 is-150 to-162 ℃, and the temperature of BOG to be condensed at the BOG inlet 3 is 0 to-100 ℃.

9. The method of claim 7, wherein: the downward spraying speed of LNG for condensing BOG from an LNG spraying hole (901) on an LNG spraying plate (9) is 3-4 m/s.

Technical Field

The invention belongs to the technical field of BOG (liquefied natural gas boil-off) treatment, and relates to a BOG recondenser and a BOG recondensing method.

Background

In an LNG (liquefied natural gas) receiving station, a BOG recovery process mainly includes direct compression export and pressurization, gasification and export after being condensed into LNG by a recondenser. The direct compression external transportation process needs low-pressure users or low-pressure external transportation pipe networks matched with the downstream, and the downstream external transportation pipe networks of domestic LNG receiving stations are generally high-pressure pipe networks and lack related matched industries, so that the BOG gas is usually recovered by adopting a re-condensation process. In the recondensing process, the BOG recondenser is the main equipment, and plays a central role in the whole operation of the receiving station after the start. The primary function of the BOG recondenser is to provide sufficient contact time and space for the BOG and LNG to cause the BOG to condense into LNG. The BOG recondenser also serves as an inlet buffer tank for the LNG high-pressure pump to ensure the inlet pressure of the high-pressure pump. The BOG recondenser mainly has two structures, namely a double-shell double-tank structure and a single-shell single-tank structure, all uses packing, and the difference in operation is mainly reflected in different control modes. The BOG recondensor directly utilizes the cold energy of LNG to condense and liquefy the BOG, and the condensing capacity is low. When the BOG treatment capacity is large, the BOG cannot be completely condensed, and the uncondensed BOG is generally sent to a flare to be burned, so that waste is caused.

Disclosure of Invention

The invention aims to provide a BOG recondenser and a BOG recondensing method, which aim to solve the problem of low condensing capacity of the conventional BOG recondenser.

In order to solve the problems, the invention adopts the technical scheme that: the utility model provides a BOG recondensor, is equipped with the shell, and the shell includes vertical cylinder barrel and top head and bottom head, and inside is equipped with the filler, is equipped with BOG entry, LNG entry and LNG export on the shell, its characterized in that: a top buffer baffle plate, an LNG injection plate, a gas-liquid distribution plate, a filler top plate, a filler bottom plate, a bottom buffer baffle plate and a vertical liquid nitrogen riser are arranged in the shell from top to bottom, LNG injection holes are formed in the LNG injection plate, gas-liquid distribution holes are formed in the gas-liquid distribution plate, the filler is arranged between the filler top plate and the filler bottom plate, the liquid nitrogen riser penetrates through the LNG injection plate, the gas-liquid distribution plate, the filler top plate, the filler and the filler bottom plate, the bottom of the liquid nitrogen riser is arranged on the bottom buffer baffle plate, the top of the liquid nitrogen riser is arranged on the top buffer baffle plate, the space above the top buffer baffle plate in the shell is a top liquid nitrogen buffer space, the space between the LNG injection plate and the liquid nitrogen riser is an LNG buffer space, the space between the LNG injection plate, the gas-liquid distribution plate and the liquid nitrogen riser is a gas-, the space below the bottom buffer baffle is a bottom liquid nitrogen buffer space, a liquid nitrogen inlet and a liquid nitrogen outlet are arranged on the shell, the bottom of the liquid nitrogen inlet and the bottom of the liquid nitrogen ascending pipe are communicated with the bottom liquid nitrogen buffer space, the top of the liquid nitrogen outlet and the top of the liquid nitrogen ascending pipe are communicated with the top liquid nitrogen buffer space, the BOG inlet is communicated with the gas-liquid mixing space, the LNG inlet is communicated with the LNG buffer space, and the LNG outlet is communicated with the LNG liquid phase space.

The BOG recondensation method of the invention adopts the BOG recondensor, the liquid nitrogen used for condensing BOG enters the liquid nitrogen buffer space at the bottom from the liquid nitrogen inlet, then enters the liquid nitrogen riser from the bottom of the liquid nitrogen riser and flows upwards, the LNG used for condensing BOG enters the LNG buffer space from the LNG inlet, then is sprayed downwards from the LNG spray hole on the LNG spray plate and enters the gas-liquid mixing space, the BOG to be condensed enters the gas-liquid mixing space from the BOG inlet and is mixed with the LNG in the gas-liquid mixing space, the mixed gas-liquid mixture flows downwards through the gas-liquid distribution holes on the gas-liquid distribution plate and enters the filler through the filler top plate for further contact and mixing, in the gas-liquid mixing space and the filler, under the action of the liquid nitrogen used for condensing BOG and in the liquid nitrogen riser, the BOG gradually condenses into the liquid phase, the liquid phase flows downwards into the LNG liquid phase space through the filler bottom plate, the LNG further condenses and flows out of the LNG outlet from the LNG in, and liquid nitrogen in the liquid nitrogen ascending pipe flows into the top liquid nitrogen buffer space from the top of the liquid nitrogen ascending pipe and then flows out of the BOG recondensor from the liquid nitrogen outlet.

The invention has the following beneficial effects: liquid nitrogen is used as an auxiliary medium, BOG is condensed together with LNG to liquefy the BOG, the BOG treatment capacity can be improved, the BOG is completely condensed as far as possible, and the problem that the uncondensed BOG is sent to a torch to be burnt and waste is caused is avoided. The invention is mainly used for the LNG receiving station to carry out recondensation and recovery on the BOG.

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The drawings and detailed description do not limit the scope of the invention as claimed.

Drawings

FIG. 1 is a schematic diagram of the BOG recondenser of the present invention.

Fig. 2 is a cross-sectional view of the LNG spraying panel of fig. 1 taken horizontally downward.

FIG. 3 is a cross-sectional view of the gas-liquid distribution plate of FIG. 1 taken horizontally downward.

Fig. 4 is a cross-sectional view of the filler head plate of fig. 1 taken horizontally down.

Fig. 5 is a cross-sectional view of the bottom cushioning flap of fig. 1 taken horizontally down above the flap.

In fig. 1 to 5, the same reference numerals denote the same technical features.

Detailed Description

Referring to fig. 1, 2, 3, 4 and 5, the BOG recondenser of the present invention is provided with a shell 1, the shell 1 comprising a vertical cylindrical shell and top and bottom heads, and packing 14 provided inside. The shell 1 is provided with a BOG inlet 3, an LNG inlet 2, an LNG outlet 4, a liquid nitrogen inlet 5 and a liquid nitrogen outlet 6. A top buffer baffle 7, an LNG injection plate 9, a gas-liquid distribution plate 10, a filler top plate 11, a filler bottom plate 12 and a bottom buffer baffle 8 are arranged in the shell 1 from top to bottom, and a vertical liquid nitrogen ascending pipe 13 is further arranged. The cross section of the liquid nitrogen ascending pipe 13 is circular. The top buffer baffle 7, the LNG injection plate 9, the gas-liquid distribution plate 10, the filler top plate 11, the filler bottom plate 12 and the bottom buffer baffle 8 are all round flat plates and are horizontally arranged, and the edges of the round flat plates are connected to the inner wall of the vertical cylindrical barrel of the shell 1. The LNG spraying plate 9 is provided with an LNG spraying hole 901 for spraying LNG downward; the gas-liquid distribution plate 10 is provided with gas-liquid distribution holes 101 for uniformly distributing gas-liquid downwards. The packing 14 is arranged between the packing top plate 11 and the packing bottom plate 12, and the packing top plate 11 and the packing bottom plate 12 can adopt various structures.

The liquid nitrogen riser 13 penetrates through the LNG injection plate 9, the gas-liquid distribution plate 10, the filler top plate 11, the filler 14 and the filler bottom plate 12; the bottom of the liquid nitrogen ascending pipe 13 is arranged on the bottom buffer baffle plate 8, and the top of the liquid nitrogen ascending pipe is arranged on the top buffer baffle plate 7. And through holes are formed in the plates, and the liquid nitrogen supply ascending pipe 13 penetrates through the through holes or the top and the bottom of the liquid nitrogen ascending pipe 13 are installed.

In the shell 1, the space above the top buffer baffle 7 is a top liquid nitrogen buffer space 15, the space between the top buffer baffle 7, the LNG injection plate 9 and the liquid nitrogen rising pipe 13 is an LNG buffer space 17, the space between the LNG injection plate 9, the gas-liquid distribution plate 10 and the liquid nitrogen rising pipe 13 is a gas-liquid mixing space 18, the space between the packing bottom plate 12, the bottom buffer baffle 8 and the liquid nitrogen rising pipe 13 is an LNG liquid phase space 19, and the space below the bottom buffer baffle 8 is a bottom liquid nitrogen buffer space 16. The liquid nitrogen inlet 5 and the bottom of the liquid nitrogen ascending pipe 13 are communicated with the liquid nitrogen buffer space 16 at the bottom, the liquid nitrogen outlet 6 and the top of the liquid nitrogen ascending pipe 13 are communicated with the liquid nitrogen buffer space 15 at the top, the BOG inlet 3 is communicated with the gas-liquid mixing space 18, the LNG inlet 2 is communicated with the LNG buffer space 17, and the LNG outlet 4 is communicated with the LNG liquid phase space 19.

Referring to fig. 1 to 5, in one embodiment of the present invention, a liquid nitrogen rising pipe 13 is provided on the axis of the casing 1, and one or more circles of liquid nitrogen rising pipes 13 are provided around the liquid nitrogen rising pipe 13 (two circles of liquid nitrogen rising pipes 13 are provided as shown in fig. 2 to 5). On a horizontal plane perpendicular to the liquid nitrogen ascending pipe 13, a circle of liquid nitrogen ascending pipes 13 are distributed in a regular hexagon (as shown in fig. 2 to 5) or in a circle (not shown), and are uniformly spaced. The liquid nitrogen rising pipe 13 can also be uniformly arranged in other modes so as to effectively utilize the space in the shell 1 and obtain good cold energy transfer effect.

Referring to fig. 2, the LNG spraying holes 901 formed in the LNG spraying plate 9 are generally circular holes, and are distributed in a regular triangle on the LNG spraying plate 9 and are fully distributed on the LNG spraying plate 9. The diameter of the LNG injection hole 901 is generally 5 to 10 mm, and the distance (the center distance) between two adjacent LNG injection holes 901 is generally 2 to 3 times of the diameter of the LNG injection hole 901.

Referring to fig. 3, the gas-liquid distribution holes 101 formed in the gas-liquid distribution plate 10 are generally circular holes, and are distributed in a regular triangle on the gas-liquid distribution plate 10 and are fully distributed in the gas-liquid distribution plate 10. The diameter of the gas-liquid distribution hole 101 is generally 2-3 times of the diameter of the LNG injection hole 901, and the distance (center distance) between two adjacent gas-liquid distribution holes 101 is generally 2-3 times of the diameter of the gas-liquid distribution hole 101.

Referring to fig. 4, the filler top plate 11 is provided with a hole 20, the hole 20 is a circular hole, and the filler top plate 11 is distributed in a regular triangle shape and is fully covered with the filler top plate 11. The packing bottom plate 12 has the same structure as the packing top plate 11. The opening rate of the openings 20 on the packing top plate 11 and the packing bottom plate 12 is as large as possible, so that the gas-liquid passage is prevented from being blocked. The packing plate 12 is used to support the packing 14 and has openings 20 that are smaller than the size of the packing 14 to prevent the packing 14 from falling out.

The LNG injection holes 901, the gas-liquid distribution holes 101, and the openings 20 may be distributed in a rectangular shape or in other regular shapes, which are not shown in the drawing.

Fig. 5 shows the structure of the bottom baffle plate 8, and the structure of the top baffle plate 7 is the same as that of the bottom baffle plate 8.

Referring to fig. 1, a BOG inlet 3 and an LNG inlet 2 are provided at an upper portion of a vertical cylindrical barrel of a housing 1, an LNG outlet 4 is provided at a lower portion of the vertical cylindrical barrel of the housing 1, a liquid nitrogen inlet 5 is provided at a bottom end of the housing 1, and a liquid nitrogen outlet 6 is provided at a top end of the housing 1.

The packing 14 is typically pall ring packing, raschig ring packing or various structured packing.

The materials for the components of the BOG recondenser mentioned above are generally stainless steel.

The BOG recondensation method of the invention adopts the BOG recondensor. Referring to fig. 1, the specific working process is that liquid nitrogen used for condensing BOG enters a bottom liquid nitrogen buffer space 16 from a liquid nitrogen inlet 5, and then enters a liquid nitrogen ascending pipe 13 from the bottom of the liquid nitrogen ascending pipe 13 to flow upwards. LNG used for condensing BOG enters the LNG buffer space 17 from the LNG inlet 2, and is then injected downward from the LNG injection holes 901 in the LNG injection plates 9 and enters the gas-liquid mixing space 18. The LNG is sprayed downward to provide a good spraying effect under the LNG spraying plate 9, so that the LNG can be uniformly and well contacted and mixed with the BOG in the gas-liquid mixing space 18.

BOG which is from a compressor and needs to be condensed enters the gas-liquid mixing space 18 from the BOG inlet 3 and is fully mixed with LNG in the gas-liquid mixing space 18, and the mixed gas-liquid mixture flows downwards through gas-liquid distribution holes 101 in the gas-liquid distribution plate 10 and enters the filler 14 through the filler top plate 11 to be further contacted and mixed. In the gas-liquid mixing space 18, the gas-liquid distribution plate 10, the space between the filler top plate 11 and the liquid nitrogen riser 13 and the filler 14, the BOG is gradually condensed into a liquid phase (i.e., LNG) under the action of the LNG used for condensing the BOG and the liquid nitrogen in the liquid nitrogen riser 13. The liquid phase and the LNG originally used for condensing BOG flow downwards into an LNG liquid phase space 19 through a packing bottom plate 12, are further condensed by liquid nitrogen in a liquid nitrogen ascending pipe 13, then flow out of a BOG recondensor from an LNG outlet 4, and enter a downstream LNG high-pressure output pump. The liquid nitrogen in the liquid nitrogen ascending pipe 13 flows into the top liquid nitrogen buffer space 15 from the top of the liquid nitrogen ascending pipe 13 and then flows out of the BOG recondensor from the liquid nitrogen outlet 6. In the above working process, LNG used for condensing BOG condenses BOG by directly mixing with BOG, and liquid nitrogen used for condensing BOG condenses BOG by indirectly supplying cold to BOG through the wall of the liquid nitrogen rising pipe 13. In fig. 1, arrows without reference numerals indicate the flow directions of streams of BOG, LNG, liquid nitrogen, and the like, respectively.

The temperature of the liquid nitrogen for condensing BOG at the liquid nitrogen inlet 5 is generally-180 to-196 ℃, and the pressure is generally 0.5 to 1.2 MPa. The temperature of LNG used for condensing BOG at the LNG inlet 2 is generally-150 to-162 ℃, and the pressure is generally 0.3 to 0.8 MPa. The temperature of BOG to be condensed at the BOG inlet 3 is generally 0 to-100 ℃, and the pressure is generally 0.3 to 0.8 MPa. The temperature of LNG at the LNG outlet 4 is generally not higher than-130 ℃, and the pressure is generally 0.4-0.9 MPa. The pressures mentioned in the present invention are gauge pressures.

The downward spraying speed of the LNG for condensing BOG from the LNG spraying holes 901 on the LNG spraying plate 9 is generally 3 to 4 m/s.