CN115507618A

CN115507618A - Concurrent BOG recondenser

Info

Publication number: CN115507618A
Application number: CN202211196421.7A
Authority: CN
Inventors: 文晓龙; 陈建华; 谢腾腾; 李金波; 王海鹏; 杨作万; 胡华震; 李海涛; 张婷
Original assignee: Shanghai Lanbin Petrochemical Equipment Co Ltd; Lanpec Technologies Ltd
Current assignee: Shanghai Lanbin Petrochemical Equipment Co Ltd; Lanpec Technologies Ltd
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2022-12-23

Abstract

The invention discloses a concurrent BOG recondenser, wherein a BOG inlet is arranged in the center of the top of a recondenser shell, and a radial distributor is arranged on the inner side of the BOG inlet; an LNG inlet is arranged on the shell below the radial distributor and is communicated with a rapid distribution pipe arranged in the shell; and a runner type distribution disc and a labyrinth type mesh packing component are sequentially arranged under the rapid distribution pipe to form a BOG downstream recondensing device. In the invention, the BOG descends to be fully contacted with the supercooled LNG on the runner type distribution disc arranged at the LNG inlet, so that gradual liquefaction is realized, the aim of thorough liquefaction is fulfilled through the labyrinth mesh packing assembly, the reprocessing process of the BOG phase-changed LNG is completed, and the condensation effect and efficiency are improved.

Description

Concurrent BOG recondenser

Technical Field

The invention relates to the field of LNG receiving stations, in particular to a recondenser for recycling BOG generated by an LNG receiving station and carrying out secondary conveying after cooling and liquefying.

Background

In recent years, with the rapid development of economy in China, the energy demand is greatly increased, especially natural gas as clean energy occupies more and more proportion in an energy structure, and with the great increase of the LNG import amount, the construction of an LNG receiving station in China is rapidly expanded. Due to technical limitations, LNG is currently traded internationally primarily by large LNG carriers. After the LNG in the cryogenic state is delivered from the carrier, boil-off gas BOG is inevitably generated by heat exchange with the outside during storage, transportation, and the like. And a large amount of BOG produces, will reduce the factor of safety of equipment such as storage tank, poses serious threat to LNG receiving station safety, consequently, just must handle BOG as soon as possible, and BOG's direct discharge not only can cause environmental pollution, also can cause energy waste and economic loss simultaneously. Therefore, one of the important processes of the LNG receiving station is a BOG processing process.

Currently, the BOG treatment process is roughly three: 1. torch burning; 2. a direct compression process; 3. and (4) carrying out a recondensing process. Torch burning energy loss is serious and is not advisable; the direct compression process requires less equipment, is simple to operate and has high process energy consumption; the re-condensation process adopts the existing supercooled LNG as a cold source, BOG is condensed, although process equipment is added, the cost of the re-condensation process is saved by 30% -60% compared with that of a direct compression process under the same condition in the long run, so that the re-condensation process is preferentially selected by an LNG receiving station from the aspect of cost, but the internal part design of the current re-condenser still has defects, BOG enters the equipment and is unevenly distributed, a vortex shape is formed, an LNG distribution disc is unevenly distributed, overflow can be caused locally, a flow channel is too long after liquid is reduced, rapid and uniform distribution cannot be achieved, the part design is complex, the installation is difficult, and the like.

From the analysis, the recondensing process has wide market prospect, but still has the problem of overlarge energy consumption, and has larger optimization space in the aspects of the design and the structure of process internals.

Disclosure of Invention

The invention provides an optimized concurrent BOG recondenser, which enables BOG to be in rapid and full contact with subcooled LNG, improves the condensation rate and reduces the energy consumption.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a concurrent BOG recondenser comprises a BOG inlet arranged at the center of the top of a recondenser shell, and a radial distributor arranged at the inner side of the BOG inlet; an LNG inlet is arranged on the shell below the radial distributor and is communicated with a rapid distribution pipe arranged in the shell; and a runner type distribution disc and a labyrinth type mesh packing component are sequentially arranged under the rapid distribution pipe to form a BOG downstream recondensing device.

The structure of the radial distributor is as follows: the main part is wide cone shell, upper portion and BOG entry intercommunication, the peripheral and bottom equipartition through-hole of casing.

The quick distribution pipe comprises a flow dividing pipe communicated with the LNG inlet, the bottom of the flow dividing pipe is uniformly connected with a plurality of downcomers in a through mode, and the outlet of each downcomer is opposite to the straight-through type collecting groove in the center of the flow channel type distribution disc.

The outlet end of the downcomer is structurally a sawtooth-shaped flow guide opening.

And a splash-proof plate is arranged above the outlet end of the downcomer.

The structure of runner formula distribution dish does: the center is a straight-through collecting tank, a plurality of groove-type distributors are arranged on two sides of the straight-through collecting tank in a penetrating way, and a plurality of cyclone mixers are arranged on the outer wall of each groove-type distributor in a penetrating way.

The length of the groove-type distributor becomes shorter from the center to the outside.

And a Raschig ring assembly is arranged between the straight-through collecting tank and the outlet of the downcomer.

Through reasonable process device design and structural transformation, the radial distributor is arranged at the top, and the radial distributor solves the rotational flow problem of the BOG, so that the BOG is radially and quickly uniformly distributed in the equipment cylinder; the LNG inlet is provided with a quick distribution pipe for feeding liquid in the middle, and the device solves the problems of long LNG flow channel and uneven distribution in the past, so that the LNG is quickly distributed on the flow channel type distribution plate; the runner type distribution disc adopts the direct connection of the straight-through type collecting groove and the groove type distributor, the LNG circulation path is shortened, the problem of complex and unpractical structure in the past is solved, the efficiency is improved, and the purchasing and manufacturing cost is reduced.

Drawings

FIG. 1 is a schematic structural view of the present invention;

fig. 2 is a schematic structural view of the rapid distribution pipe of the present invention;

FIG. 3 is a top view of FIG. 2;

FIG. 4 is a schematic structural diagram of a flow channel distribution plate according to the present invention;

FIG. 5 is a top view of FIG. 4;

FIG. 6 is a schematic view of the radial distributor of the present invention;

FIG. 7 is a view taken along line A of FIG. 6;

FIG. 8 is a schematic diagram of the construction of a cyclonic mixer of the present invention;

fig. 9 is a view taken along direction a in fig. 8.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1, a concurrent BOG recondenser having a BOG inlet provided at the center of the top of a recondenser shell and a radial distributor 1 provided inside the BOG inlet; be provided with the LNG entry on the casing of the below of this radial distributor 1, this LNG entry with set up the 2 intercommunications of quick distribution pipe in the casing, and set gradually runner formula distribution disc 3 and labyrinth mesh packing assembly 4 under quick distribution pipe 2 and constitute BOG's following current recondensing device.

The labyrinth mesh packing component 4 belongs to structured packing, the conventional packing adopts bulk packing, the gap is large, the packing is uneven, gas and liquid cannot be fully contacted, the condensation efficiency is low, uniform small holes are formed in each plate of the structured packing, the plates are pressed into a plurality of concave-convex structures by a die, and the small holes between the plates are communicated in a staggered mode, so that BOG and LNG uniformly and stably flow through the plates, full mixing contact is achieved, and BOG is further condensed. The labyrinth mesh packing assembly 4 is supported by a support frame 5 mounted inside the housing.

Referring to fig. 6 and 7, the radial distributor 1 has the following structure: the main part is wide cone shell, upper portion and BOG entry intercommunication, the peripheral and bottom equipartition through-hole of casing. After entering the tank body, the BOG is quickly and uniformly distributed in a radial shape in the diameter range of the equipment immediately under the action of the radial distributor 1, and simultaneously plays a role in baffling to a certain extent, the angle of the cone is determined according to the diameter of the equipment, and the size and the number of the openings are determined according to the flow; the former equipment adopts simple baffle plates or has no shielding, so that vortexes and uneven distribution are easily caused after the BOG enters the equipment, and the condensation efficiency of the BOG is reduced.

Referring to fig. 2 and 3, the fast distribution pipe 2 includes a shunt pipe communicated with the LNG inlet, the bottom of the shunt pipe 8 is uniformly connected with a plurality of downcomers 7 in a through manner, and the outlet of the downcomer 7 is opposite to a straight-through collecting tank 11 in the center of the runner distribution disc 3.LNG enters the main pipe and then enters the main pipe from the middle of the flow dividing pipe, and then is divided to two ends simultaneously, a row of downcomers are arranged at the lower part of the flow dividing pipe, and the LNG flows down from the downcomers step by step in the flow dividing pipe.

Referring to fig. 3, the outlet end of the downcomer 7 is structured as a zigzag deflector. The zigzag flow guide port plays a role in flow guide and flow stabilization so as to avoid causing large splashing.

Referring to fig. 3, a splash plate 6 is disposed above the outlet end of the downcomer 7. The splash guard 6 plays a role in preventing LNG from splashing and is arranged at the root of the lower end of the downcomer as much as possible, so that the splash guard has a better splash-proof effect.

Referring to fig. 4 and 5, the flow channel distribution plate 3 has the following structure: the center is a straight-through collecting tank 11, a plurality of groove-type distributors 9 are arranged on two sides of the straight-through collecting tank 11 in a penetrating way, and a plurality of swirl mixers 10 are arranged on the outer wall of each groove-type distributor 9 in a penetrating way.

The length of the trough distributor 9 becomes shorter from the center to the outside. Under the action of pressure drop, the pressure drop is smaller at the position closer to the center of the flow dividing pipe, the flow of the downcomer is larger when the pressure drop is smaller, and the groove of the groove type distributor 9 close to the center of the equipment is also longer; on the contrary, the downcomer far away from the center of the shunt pipe has large pressure drop, small flow and short groove. Therefore, the flow rate of the place with the long groove is large, and the flow rate of the place with the short groove is small, so that the LNG can be rapidly and uniformly distributed on the groove-type distributor 9. The distribution pipe in the past is directly to be responsible for and stretch into the equipment other end, and under the effect of pressure drop, the downcomer flow that is close to the import of equipment more is just big, and the flow is just little more far away, and the groove of the groove type distributor 9 that is close to the import is short on the contrary, causes local overflow, and local not enough phenomenon, unable evenly distributed, greatly reduced BOG's condensation efficiency.

Referring to fig. 8 and 9, an arc-shaped flow guide part 12 is arranged at the through hole communication position on the tank body wall of the cyclone mixer 10 and the tank type distributor 9, and the arc-shaped flow guide part 12 plays a role of cyclone LNG. The cyclone mixer 10 is welded on the outer side of the side wall of the tank body of the tank distributor 9, a through hole is formed in the side wall from top to bottom, LNG flows out from the small hole and then is sprayed onto the cyclone mixer 10 to be subjected to cyclone, so that the LNG and BOG are fully mixed and contacted, the purpose of efficient condensation is achieved, the outlet at the bottom of the cyclone mixer 10 is designed into a sawtooth shape (shown in figure 8), and the flowing liquid is guided.

A Raschig ring assembly is arranged between the outlet of the downcomer 7 and the straight-through collecting tank 8. The LNG falling from the downcomer further has the flow stabilizing effect, so that the LNG stably flows out from the side opening (directly connected with the trough distributor) at the bottom of the trough and is quickly distributed into the trough distributor 9.

The working principle of the invention is as follows:

BOG enters from the top, and is quickly baffled and uniformly distributed in a radial mode through the radial distributor 1, so that the BOG uniformly descends to the flow channel type distribution disc 3 from the inner diameter surface of the equipment. LNG gets into from the import, divide the reposition of redundant personnel fast by the centre through quick distribution pipe 2, from the straight-through collecting vat 8 of downcomer flow to runner formula distribution disc 3, straight-through collecting vat is directly connected with slot type distributor 9, in flowing into the slot through curb plate trompil, reach quick evenly distributed, slot type distributor 9 lateral wall is opened there is equidistant aperture, LNG passes in the aperture gets into whirl mixer 10, just in time fully contact with descending BOG, reach condensation BOG mesh, BOG and LNG that do not condense continue down, pass labyrinth mesh filler subassembly 4 and continue fully contact, continue the condensation, reach the complete BOG of final condensation, BOG becomes LNG and gets into next flow through the bottom mouth of pipe.

Claims

1. The concurrent BOG recondenser is characterized in that a BOG inlet is formed in the center of the top of a recondenser shell, and a radial distributor (1) is arranged on the inner side of the BOG inlet; an LNG inlet is arranged on the shell below the radial distributor (1), and the LNG inlet is communicated with a rapid distribution pipe (2) arranged in the shell; and a runner type distribution disc (3) and a labyrinth type mesh packing component (4) are sequentially arranged under the rapid distribution pipe (2) to form a BOG downstream recondensing device.

2. Concurrent BOG recondenser according to claim 1, wherein the radial distributor (1) is configured to: the main part is wide cone shell, upper portion and BOG entry intercommunication, the peripheral and bottom equipartition through-hole of casing.

3. Concurrent BOG recondenser according to claim 1, wherein the fast distribution pipe (2) comprises a dividing pipe (8) communicating with the LNG inlet, the bottom of the dividing pipe (8) is connected with a plurality of downcomers (7) uniformly through, and the outlet of the downcomers (7) is opposite to the straight-through collecting groove (11) in the center of the flow channel distribution plate (3).

4. Concurrent BOG recondenser according to claim 3, wherein the structure at the outlet end of the downcomer (7) is a zigzag deflector.

5. Concurrent BOG recondenser according to claim 3, wherein a splash plate (6) is provided above the outlet end of the downcomer (7).

6. Concurrent BOG recondenser according to claim 1, wherein the flow-path distribution plate (3) is structured: the center is a straight-through collecting tank (11), a plurality of groove type distributors (9) are arranged on two sides of the straight-through collecting tank (11) in a penetrating way, and a plurality of cyclone mixers (10) are arranged on the outer wall of each groove type distributor (9) in a penetrating way.

7. Concurrent BOG recondenser according to claim 6, wherein the communicating through holes in the walls of the swirl mixer (10) and the trough distributor (9) are provided with curved flow guides (12).

8. Concurrent BOG recondenser according to claim 6, wherein the length of the trough distributor (9) becomes shorter from the centre outwards.

9. Concurrent BOG recondenser according to claim 6, wherein Raschig ring assemblies are provided between the straight-through collection trough (11) and the outlet of the downcomer (7).