CN213629884U

CN213629884U - Automatic control system for combined operation of recondenser and direct external transmission

Info

Publication number: CN213629884U
Application number: CN202022556849.0U
Authority: CN
Inventors: 傅皓; 刘利; 朱春早; 郑达
Original assignee: China Chengda Engineering Co Ltd
Current assignee: China Chengda Engineering Co Ltd
Priority date: 2020-11-06
Filing date: 2020-11-06
Publication date: 2021-07-06
Anticipated expiration: 2030-11-06

Abstract

The utility model discloses an automatic control system of recondensor and direct defeated joint operation outward, including direct defeated branch road outward and recondensation branch road, the BOG that comes from the storage tank is connected with the direct defeated branch road outward and the recondensation branch road of parallelly connected setting respectively after the compression unit compression the equipment upper reaches of direct defeated branch road outward are provided with pressure transmitter and pressure regulating valve, pressure transmitter is located the export of compression unit, and with recondensation branch road on recondensation gaseous phase entry UNICOM. The utility model discloses an equipment upper reaches in direct defeated branch road outward sets up pressure regulation return circuit, and its hardware increases fewly, easily realizes to can be under the prerequisite of stabilizing recondensor pressure, stable operation when accomplishing BOG direct defeated technology of outward and BOG recondensor technology improves the stability and the flexibility that the receiving station BOG handled greatly, the fully applicable large-and-medium-sized LNG receiving station.

Description

Automatic control system for combined operation of recondenser and direct external transmission

Technical Field

The utility model belongs to the technical field of liquefied hydrocarbon evaporation gas retrieves, in particular to recondensor and direct defeated combined operation's automatic control system outward.

Background

Liquefied Natural Gas (LNG) is a volatile liquefied hydrocarbon, and its boil-off gas (BOG) is mainly caused by external energy input, such as pump operation, external heat introduction, atmospheric pressure change, environmental influence, change in gas phase volume in a tank caused when LNG is injected into a storage tank, and generation and return of vapor during tank car loading operation. From the viewpoint of environmental protection and economic efficiency, the blow-down of the BOG (boil-off gas) gas should be avoided as much as possible, and therefore, the BOG (boil-off gas) must be subjected to a recovery treatment.

At present, boil-off gas (BOG) processing schemes of a Liquefied Natural Gas (LNG) receiving station are mainly two: the main difference between the direct export process and the recondensing process is the different way of treating the boil-off gas.

The direct output process is to utilize a BOG compressor to directly compress the evaporated gas to an external transmission pressure and send the compressed gas to a pipe network, wherein the BOG compressor can be a low-pressure compressor or a high-pressure compressor according to different pressures of the connected external transmission pipe network.

The recondensation process is to pressurize the BOG to a lower pressure by a compressor, mix the BOG with LNG sent from an LNG storage tank in a recondensor, and perform cold exchange. Because the LNG is in a supercooled state after being pressurized, the evaporated gas can be re-condensed, then pressurized by a high-pressure delivery pump, gasified by a gasifier and output. The recondensation process can utilize the cold energy of the LNG and reduce the consumption of Boil Off Gas (BOG) compression work. Which process scheme is used depends on the export requirement.

Originally, BOG treatment is generally carried out by using a low-energy-consumption recondensing technology in China, but when the initial stage of a project is found in actual operation, the gasification output is generally small, the condensation is not enough for all the produced BOG, and the redundant BOG can only be discharged to a flare and burnt. Moreover, the recondenser is sensitive to BOG flow fluctuation, and system trip is easily caused by improper adjustment, so that the external output stability is greatly influenced; in addition, the recondenser is used as a pressure vessel, so that the need of regular maintenance is met, BOG treatment cannot be performed under the condition that the BOG recondenser is maintained, and only the BOG recondenser can be emptied, so that waste is caused.

At present, the respective operating loads of two sets of process systems need to be manually adjusted by an operator according to the fluctuation condition of related parameters, so that most receiving stations separately operate two processes, and the problems of limited operating flexibility, increased operating cost and the like are caused.

SUMMERY OF THE UTILITY MODEL

The invention of the utility model aims to: aiming at the technical problems, the automatic control system for the combined operation of the recondenser and the direct output can complete two processes and simultaneously stably operate on the premise of stabilizing the pressure of the recondenser, so that the BOG processing stability and flexibility of the receiving station are greatly improved.

The technical scheme of the utility model is realized like this: an automated recondensor and direct export system, comprising: including direct defeated branch road and recondensation branch road, the BOG who comes from the storage tank is connected with the direct defeated branch road of defeated outward and the recondensation branch road of parallelly connected setting respectively after the compression unit compression the equipment upper reaches of direct defeated branch road is provided with pressure transmitter and pressure regulating valve, pressure transmitter is located the export of compression unit, and with recondensor gaseous phase entry UNICOM on the recondensation branch road.

Recondensor and direct defeated combined operation's automatic control system outward, its the compression unit comprises an at least BOG compressor, works as when the BOG compressor is many, many parallelly connected settings of BOG compressor, pressure transmitter is located BOG compressor export one side.

Recondensor and direct defeated combined operation's automatic control system outward, it divide into two the tunnel after the BOG compressor compression, wherein low pressure BOG gets into the direct defeated branch road outward all the way, another way low pressure BOG gets into the recondensation branch road.

Recondensor and direct defeated automatic control system who jointly moves outward, it direct defeated branch road exit end outward links to each other with high-pressure pipe network, direct defeated outward is provided with BOG booster compressor on the road, pressure transmitter and pressure regulating valve set up at BOG booster compressor upper reaches, get into the BOG of direct defeated branch road outward behind BOG booster compressor compresses into high-pressure BOG, exports high-pressure pipe network outward.

Recondensor and direct defeated combined operation's automatic control system outward, it direct defeated branch road exit end outward links to each other with the low pressure pipe network, direct defeated branch road outward is provided with the reheat unit on, pressure transmitter and pressure regulating valve set up at the reheat unit upper reaches, get into the BOG of direct defeated branch road outward and after the reheat unit heating, export the low pressure pipe network outward.

Recondensor and direct defeated combined operation's automatic control system outward, its reheating unit is empty temperature formula heater or electric heater.

Recondensor and direct defeated combined operation's automatic control system outward, it recondensation branch road exit end links to each other with high-pressure pipe network recondensation branch road has set gradually recondensor and high-pressure pump and vaporizer on, the BOG that gets into the recondensation branch road is through after the recondensor condensation, after high-pressure pump and vaporizer pressurization and gasification again, exports the high-pressure pipe network outward.

The utility model discloses an equipment upper reaches in direct defeated branch road outward sets up pressure regulation return circuit, and its hardware increases fewly, easily realizes to can be under the prerequisite of stabilizing recondensor pressure, stable operation when accomplishing BOG direct defeated technology of outward and BOG recondensor technology improves the stability and the flexibility that the receiving station BOG handled greatly, the fully applicable large-and-medium-sized LNG receiving station.

Drawings

Fig. 1 is a schematic flow chart of embodiment 1 of the present invention.

Fig. 2 is a schematic flow chart of embodiment 2 of the present invention.

The labels in the figure are: 1 is the direct export branch road, 2 is the recondensing branch road, 3 is pressure transmitter, 4 is pressure regulating valve, 5 is the recondensor, 6 is the BOG compressor, 7 is the BOG booster compressor, 8 is the high pressure pipe network, 9 is the low pressure pipe network, 10 is the reheat unit, 11 is high-pressure pump and vaporizer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

It should be noted that, in the present invention, the embodiments and features of the embodiments may be combined with each other without conflict.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that the indication of the position or the positional relationship is based on the position or the positional relationship shown in the drawings, or the position or the positional relationship that the utility model is usually placed when using, or the position or the positional relationship that the skilled person conventionally understands, or the position or the positional relationship that the utility model is usually placed when using, and is only for the convenience of describing the present invention and simplifying the description, but does not indicate or suggest that the indicated device or element must have a specific position, be constructed and operated in a specific position, and thus, cannot be understood as limiting the present invention. Furthermore, the terms "first" and "second" are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed" and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present invention can be understood in specific cases for a person of ordinary skill in the art; the drawings in the embodiments are provided to clearly and completely describe the technical solutions in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all embodiments of the present invention. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.

Example 1:

as shown in fig. 1, a schematic flow chart of combined operation of BOG recondensation and high-pressure direct output process, the system specifically includes a direct output branch 1 and a recondensation branch 2, the BOG from the storage tank is compressed by a compression unit and then is respectively connected with the direct output branch 1 and the recondensation branch 2 which are arranged in parallel, a pressure transmitter 3 and a pressure regulating valve 4 are arranged on the upstream of the direct output branch 1, and the pressure transmitter 3 is located at an outlet of the compression unit and is communicated with a recondensor 5 gas phase inlet on the recondensation branch 2.

Specifically, the compression unit comprises two BOG compressors 6 that set up in parallel, pressure transmitter 3 is located BOG compressor 6 export one side, divide into two the tunnel after BOG compressor 6 compresses, and wherein low pressure BOG gets into directly defeated branch road 1 outward of one way, and another way low pressure BOG gets into recondensing branch road 2.

In this embodiment, the direct export of defeated branch road 1 exit end links to each other with high-pressure pipe network 8 outward, be provided with BOG booster compressor 7 on the direct defeated branch road 1 outward, pressure transmitter 3 and pressure regulating valve 4 set up in BOG booster compressor 7 upper reaches, and the BOG that gets into direct defeated branch road 1 outward exports high-pressure pipe network 8 outward after BOG booster compressor 7 compresses into high-pressure BOG.

The outlet end of the recondensing branch 2 is connected with a high-pressure pipe network 8, a recondenser 5, a high-pressure pump and a gasifier 11 are sequentially arranged on the recondensing branch 2, and after BOG entering the recondensing branch 2 is condensed by the recondenser 5, pressurized and gasified by the high-pressure pump and the gasifier 11, the BOG is output to the high-pressure pipe network 8.

The specific flow of this embodiment is described as follows:

BOG boil-off gas that the storage tank produced is compressed into low pressure BOG through the BOG compressor after, divide into two routes:

A) one path of low-pressure BOG is sent to a recondenser, the low-pressure BOG is mixed with LNG sent out from an LNG storage tank by an LNG low-pressure delivery pump in the recondenser, evaporated gas can be recondensed due to the fact that the LNG is in a supercooled state after being pressurized, and the condensed LNG is pressurized by an LNG high-pressure delivery pump, gasified by a gasifier and then externally output to a high-pressure pipe network.

B) And the other path of low-pressure BOG enters a BOG booster compressor (possibly comprising a buffer tank, a heat exchanger and the like), and the BOG is compressed into high-pressure BOG by the additional compressor and then is output to a high-pressure pipe network.

Arranging a pressure transmitter and a pressure regulating valve at the upstream of the BOG booster compressor, and controlling the regulating valve by taking the upstream pressure of the regulating valve; the regulating valve is closed when the pressure decreases and opened when the pressure increases to maintain the pressure at a stable value.

Because this pressure transmitter is located BOG compressor export, and with recondensor gaseous phase entry UNICOM, therefore the stability of this pressure just means recondensor gaseous phase pressure's stability, avoids taking place because of recondensor pressure fluctuation causes the condition that the system jumps the car.

Example 2:

as shown in fig. 2, which is a schematic flow chart of the combined operation of BOG recondensation and low-pressure direct export process, example 2 is basically the same as example 1, and the difference is mainly that: the direct external output branch 1 is characterized in that the outlet end is connected with a low-pressure pipe network 9, the direct external output branch 1 is provided with a reheating unit 10, the pressure transmitter 3 and the pressure regulating valve 4 are arranged on the upstream of the reheating unit 10, the reheating unit 10 is an air-temperature heater or an electric heater, and BOG entering the direct external output branch 1 is heated by the reheating unit 10 and then is output to the low-pressure pipe network 9.

The specific flow of this embodiment is described as follows:

B) And the other path of low-pressure BOG is sent to a reheating unit, the reheating unit is provided with an air temperature type heater or an electric heater and the like to heat BOG gas at the outlet of the BOG compressor, and the heated gas is output to a low-pressure pipe network.

A pressure transmitter and a pressure regulating valve are arranged at the upstream of the reheating unit, and the upstream pressure of the regulating valve is used for controlling the regulating valve; the regulating valve is closed when the pressure decreases and opened when the pressure increases to maintain the pressure at a stable value.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. An automated recondensor and direct export system, comprising: including direct defeated branch road (1) and recondensing branch road (2), the BOG who comes from the storage tank is connected with direct defeated branch road (1) and recondensing branch road (2) that parallel arrangement respectively after the compression of compression unit the equipment upper reaches of direct defeated branch road (1) are provided with pressure transmitter (3) and pressure regulating valve (4), pressure transmitter (3) are located compression unit's export, and with recondensing branch road (2) on recondensing branch road (5) gaseous phase entry UNICOM.

2. An automated control system for operation of a recondenser in conjunction with direct take-off according to claim 1, wherein: the compression unit comprises at least one BOG compressor (6), when BOG compressor (6) are many, many BOG compressors (6) parallel arrangement, pressure transmitter (3) are located BOG compressor (6) export one side.

3. An automated control system for operation of a recondenser in conjunction with direct take-off according to claim 2, wherein: the BOG is compressed by a BOG compressor (6) and then divided into two paths, wherein one path of low-pressure BOG enters a direct output branch (1), and the other path of low-pressure BOG enters a re-condensation branch (2).

4. An automated control system for operation of a recondenser in conjunction with direct take-off according to claim 3, wherein: the direct outer branch road (1) exit end links to each other with high-pressure pipe network (8), be provided with BOG booster compressor (7) on the direct outer branch road (1) of exporting, pressure transmitter (3) and pressure regulating valve (4) set up in BOG booster compressor (7) upper reaches, and the BOG that gets into direct outer branch road (1) exports outward is after BOG booster compressor (7) compresses into high-pressure BOG, exports high-pressure pipe network (8) outward.

5. An automated control system for operation of a recondenser in conjunction with direct take-off according to claim 3, wherein: the direct outward-conveying branch road (1) exit end links to each other with low pressure pipe network (9), be provided with compound heat unit (10) on direct outward-conveying branch road (1), pressure transmitter (3) and pressure regulating valve (4) set up at compound heat unit (10) upper reaches, and the BOG that gets into direct outward-conveying branch road (1) exports low pressure pipe network (9) outward after heat unit (10) heating.

6. An automated control system for operation of a recondenser in conjunction with direct take-off according to claim 5, wherein: the reheating unit (10) is an air temperature type heater or an electric heater.

7. An automated control system for operation of a recondenser in conjunction with direct take-off as claimed in claim 4, 5 or 6 wherein: the outlet end of the recondensing branch (2) is connected with a high-pressure pipe network (8), a recondenser (5), a high-pressure pump and a gasifier (11) are sequentially arranged on the recondensing branch (2), and BOG entering the recondensing branch (2) is condensed by the recondenser (5), pressurized and gasified by the high-pressure pump and the gasifier (11), and then output to the high-pressure pipe network (8).