CN203240270U - Near-shore type low-temperature LNG (Liquefied Natural Gas) transmission system - Google Patents

Abstract

The utility model provides a near-shore LNG low-temperature transmission system, which includes a submarine LNG delivery pipeline arranged between an offshore LNG loading and unloading platform and an onshore LNG storage tank, a submarine BOG return gas pipeline and a submarine auxiliary process facility pipeline . Among them, the submarine LNG transmission pipeline and the submarine BOG return pipeline are PIP pipelines, which realize the LNG transmission between the offshore LNG loading and unloading platform and the land LNG storage tank, and the BOG return gas balance; the submarine auxiliary process facility pipeline realizes system control and leak detection And public system material transfer and other functions. The utility model reduces the project investment cost and improves the safety of transportation, is beneficial to expand the site selection range of the LNG receiving station, and is especially suitable for projects where the offshore LNG loading and unloading platform is far from the land LNG receiving and storage terminal.

Description

A near-shore LNG cryogenic transmission system

technical field

The utility model relates to an LNG transmission system, in particular to an near-shore LNG low-temperature transmission system.

Background technique

With the continuous growth of my country's demand for clean energy, the introduction of LNG (liquefied natural gas, liquefied natural gas) has become an effective way to solve energy problems. The rapid development of the LNG industry has drawn widespread attention to the construction of LNG receiving terminals. At present, the selection of conventional onshore LNG receiving terminal sites and port sites is greatly influenced by the surrounding environment and land resource constraints. Generally, an onshore LNG receiving terminal must be equipped with a transmission structure to ensure smooth delivery of LNG from the LNG carrier to the onshore LNG storage tank. Most trestle-type transmission structures are now used to support LNG transmission pipelines and utility systems, and many trestle-type transmission structures require vehicles to directly enter the unloading terminal. The main influencing factors of its cost include: length of trestle, water depth, soil conditions, number and size of piping system, vehicle and pedestrian access requirements, environmental conditions (waves and tides, etc.), materials used for facilities, methods of construction and installation, security requirements, etc. If the location of the loading and unloading platform is far from the coast, it means huge investment, longer construction period and more difficult inspection and maintenance.

Therefore, on the basis of fully considering technical feasibility, safety and economy, the present invention proposes a new offshore LNG low-temperature pipeline transmission system to reduce the investment cost of the project and increase the effective transportation distance of LNG; and through the pipeline The backfilling project increases the safety of the transportation system, reduces the loss of transportation cooling capacity, realizes the optimization of the entire system, and further improves the limitations of the site selection of onshore LNG receiving terminals in traditional technologies.

Contents of the invention

In view of the above problems, the purpose of this utility model is to provide a near-shore LNG low-temperature transmission system with low investment cost and high transmission safety.

In order to achieve the above object, the present invention adopts the following technical solutions: a near-shore LNG low-temperature transmission system, which is characterized in that it includes a seabed LNG delivery pipeline arranged between an offshore LNG loading and unloading platform and an onshore LNG storage tank, and the seabed BOG return gas pipeline and submarine auxiliary process facility pipeline; one end of the submarine LNG delivery pipeline is connected to the LNG loading and unloading arm of the offshore LNG loading and unloading platform, and the other end is connected to the LNG input end of the land LNG storage tank; one end of the submarine BOG return pipeline is connected to The BOG gas return arm of the offshore LNG loading and unloading platform, the other end is connected to the BOG gas return end of the onshore LNG storage tank; one end of the submarine auxiliary process facility pipeline is connected to the auxiliary facilities of the offshore LNG loading and unloading platform, and the other end is connected to the auxiliary onshore LNG storage tank Facilities; the submarine LNG transmission pipeline and the submarine BOG gas return pipeline are PIP pipes.

The above-mentioned subsea auxiliary process facility pipelines are steel pipelines.

Because the present invention adopts the above technical scheme, it has the following advantages: 1. The utility model is different from the traditional offshore gas transmission system and the land trestle type LNG low temperature transportation system. It realizes the The low-temperature LNG transportation between the offshore LNG loading and unloading platform and the onshore LNG storage tank and the return of boil-off gas BOG overcome the impact of the LNG receiving terminal being greatly affected by the surrounding environment and land resources, the long construction period of the trestle structure, and the impact of leakage or damage. People and the environment pose high risk issues. 2. The utility model has outstanding advantages in reducing investment and operating costs, saving energy in production, expanding the distance between the LNG terminal and the LNG receiving station to reduce safety risks, and expanding the site selection conditions for the LNG receiving station. The utility model is especially suitable for projects where the LNG ship unloading platform is far away from the onshore LNG receiving and storing terminal.

Description of drawings

Fig. 1 is a schematic diagram of the composition and structure of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

The invention adopts PIP (Pipe in Pipe, pipe-in-pipe) pipeline transportation technology to replace the traditional trestle-type transmission structure, and realizes unloading and transportation of LNG cargo ships, BOG (Boiled off Gas, boil-off gas) return gas balance, system control, and leakage detection And public system material transfer and other functions.

As shown in FIG. 1 , the present invention mainly consists of a subsea LNG delivery pipeline 3 arranged between an offshore LNG loading and unloading platform 1 and an onshore LNG storage tank 2 , a subsea BOG return pipeline 4 and a subsea auxiliary process facility pipeline 5 . Among them, one end of the submarine LNG delivery pipeline 1 is connected to the LNG loading and unloading arm 11 of the offshore LNG loading and unloading platform 1, and the other end is connected to the LNG input port 21 of the land LNG storage tank 2; one end of the submarine BOG return gas pipeline 4 is connected to the offshore LNG loading and unloading The BOG gas return arm 12 of the material platform 1, and the other end is connected to the BOG gas return end 22 of the land LNG storage tank 2; one end of the submarine auxiliary process facility pipeline 5 is connected to the auxiliary facility of the offshore LNG loading and unloading platform 1, and the other end is connected to the land Install the auxiliary facilities of LNG storage tank 2 to ensure the normal operation of offshore LNG loading and unloading platform 1 and land LNG storage tank 2. The subsea auxiliary process facility pipeline 5 can be a public pipeline such as instrument air pipeline, factory air pipeline, nitrogen pipeline, water supply pipeline, cable pipeline, optical cable pipeline, and auxiliary equipment such as built-in system control device and leakage detection device.

In the present invention, the submarine LNG delivery pipeline 3 and the submarine BOG return pipeline 4 are PIP (Pipe in Pipe, pipe-in-pipe), and the submarine auxiliary process facility pipeline 5 can be a conventional steel pipeline. Among them, the PIP pipeline is a new type of two-layer or three-layer structure pipeline suitable for low-temperature fluids such as LNG, including 36% nickel metal steel pipes in direct contact with low-temperature fluids, insulation layer, leak detection space and external steel pipes. The PIP pipeline is a prior art, and will not be repeated here.

LNG transportation function: Under the pressure of the unloading pump of the LNG carrier, the LNG in the LNG carrier passes through the LNG loading and unloading arm of the offshore LNG loading and unloading platform, enters the submarine LNG delivery pipeline, and is sent to the onshore LNG storage tank for storage; When the onshore LNG storage tank reversely transports LNG to the LNG carrier, the LNG in the onshore LNG storage tank enters the submarine LNG delivery pipeline under the pressure of the LNG storage tank loading pump, and then is sent to the LNG loading and unloading arm. to the LNG carrier.

BOG return gas process: When the LNG carrier is unloading, the boil-off gas (BOG) generated by the unloading in the land LNG storage tank enters the submarine BOG return gas pipeline through the BOG return gas end, and passes through the BOG loading and unloading of the offshore LNG loading and unloading platform The arm returns to the LNG carrier; when the LNG carrier is loading, the boil-off gas (BOG) generated in the LNG carrier cabin passes through the BOG loading and unloading arm of the offshore LNG loading and unloading platform, enters the submarine BOG return pipeline, and returns to the land LNG storage tank. Realize gas phase balance between LNG carrier and land LNG storage tank.

Example 1: After the LNG carrier arrives at the offshore LNG loading and unloading platform, it outputs LNG with a temperature of about -160°C and a pressure of 0.45 MPag. In the onshore LNG storage tank; at the same time, the boil-off gas (BOG) generated in the onshore LNG storage tank, with a temperature of about -150°C, enters the submarine BOG return pipeline, and then returns through the BOG return arm of the offshore LNG loading and unloading platform to LNG carriers.

Example 2: When the onshore LNG storage tank reversely transports LNG (-160°C) to the LNG carrier, the loading pump in the onshore LNG storage tank is pressurized to 0.4 MPag, and the LNG enters the submarine LNG delivery pipeline, and then passes through The LNG loading and unloading arm of the offshore LNG loading and unloading platform is transported to the LNG carrier; the boil-off gas (BOG) generated in the LNG carrier has a temperature of about -150°C, and is sent to the submarine BOG return arm through the BOG return arm of the offshore LNG loading and unloading platform. The gas pipeline returns to the onshore LNG storage tank to achieve gas phase balance.

Above-mentioned each embodiment is only for illustrating the present invention, wherein the structure of each component, connection mode etc. all can be changed to some extent, every equivalent conversion and improvement carried out on the basis of the technical solution of the present invention, all should not be excluded from the present invention. outside the scope of protection of the invention.

Claims (2)

1. offshore formula LNG cryogenic transfer system is characterized in that: it comprises the seabed LNG conveyance conduit that is arranged between marine LNG loading and unloading material platform and the land LNG storage tank, seabed BOG return-air duct and seabed auxiliary process service conduit; One end of described seabed LNG conveyance conduit connects the LNG dress unloading arm of described marine LNG loading and unloading material platform, and the other end connects the LNG input end of described land LNG storage tank; One end of described seabed BOG return-air duct connects the BOG return-air arm of described marine LNG loading and unloading material platform, and the other end connects the BOG air return end of described land LNG storage tank; One end of described seabed auxiliary process service conduit connects described marine LNG loading and unloading material platform supporting facility, and the other end connects described land LNG storage tank supporting facility; Described seabed LNG conveyance conduit and seabed BOG return-air duct are the PIP pipe.

2. a kind of offshore formula LNG cryogenic transfer system as claimed in claim 1, it is characterized in that: described seabed auxiliary process service conduit is steel pipe.

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