JP6635504B2 - Degassing device for low temperature liquefied gas piping - Google Patents

Description

  The present invention relates to a degassing device for low-temperature liquefied gas piping.

Conventionally, LNG piping degassing apparatus present applicant had adopted was constituted as shown in FIG. In the LNG pipe 100 through which LNG flows, a gate-shaped pipe section 101 (pocket section) having an upstream bent section 101a and a downstream bent section 101b is formed in order to remove gas generated inside. LNG (natural gas) vaporized is stored at the top of the portal-shaped piping section 101, a gas vent pipe 102 is connected to the upper end of the upstream bent portion 101a, and a gas vent control valve 103 is provided in the gas vent pipe 102. A differential pressure level gauge 104 for detecting a pressure difference between the liquid pressure in the LNG pipe 100 and the gas pressure in the gas vent pipe 102 is provided, and a gas vent control valve 103 is operated based on a detection signal of the differential pressure level meter 104. A control unit (not shown) for controlling is provided, and when the liquid level detected by the differential pressure type liquid level meter 104 falls below a predetermined level, the gas release control valve 103 is opened to release the gas.

  The degassing device in the low-temperature liquid pipeline described in Patent Document 1 is a degassing device having a special configuration. However, this degassing device is installed at a relatively high place in the LNG piping at the LNG receiving base. Connected in the middle of piping.

JP-A-9-166262

In the LNG pipe degassing device shown in FIG. 2 , the direction of the upward liquid flow and the direction of the upward gas flow are the same at the connection between the LNG pipe 100 and the gas vent pipe 102 at the upstream bent portion 101 a. Therefore, the gas flow easily flows into the LNG pipe, the liquid flow easily flows into the gas vent pipe 102, and the liquid level rises and fluctuates up and down. There has been a problem that the liquid level tends to be detected and the detection accuracy of the liquid level is reduced.

  An object of the present invention is to provide a low-temperature liquefied gas pipe gas venting device that can accurately detect the liquid level of a low-temperature liquefied gas at a portion where the degassing pipe is connected to the low-temperature liquefied gas pipe.

The gas venting device for a low-temperature liquefied gas pipe according to claim 1 is a gas venting device for bleeding gas from a low-temperature liquefied gas pipe through which a low-temperature liquefied gas flows, wherein the rising pipe portion, the upstream bent portion, the horizontal straight pipe portion, and the downstream bent portion. The downstream bent portion in the low-temperature liquefied gas pipe having a gate-shaped piping portion formed in a gate shape with a falling pipe portion, and a rising pipe portion rising upward from an upper end portion of the downstream bent portion. includes a gas vent pipe connected to the low-temperature liquefied gas pipe, and a differential pressure type liquid level meter for detecting the differential pressure of the liquid pressure and the venting tube of the gas pressure of the low-temperature liquefied gas in the pipe, the downstream bent portion The downstream pipe wall of the degassing pipe in the vicinity of is formed so as to be linearly continuous with the downstream pipe wall of the falling pipe in the vertical direction .

The gas venting device for a low-temperature liquefied gas pipe according to claim 2 is the gas venting device according to claim 1 , wherein the gas venting valve receives a detection signal from the gas venting control valve interposed in the gas venting tube and the differential pressure level gauge. And a control unit for controlling the extraction control valve.

Since the invention of the present application has the configuration described in the section of problem solving means, the following effects can be obtained.
According to the first aspect of the present invention, the flow direction of the low-temperature liquefied gas is changed from the horizontal direction to the downward direction at the downstream bent portion of the portal-shaped pipe portion of the low-temperature liquefied gas pipe. Since a gas vent pipe connected to the low-temperature liquefied gas pipe via a riser pipe rising upward from the upper end of the downstream bent portion is provided, a downward liquid flow and an upward gas flow at the bent portion are provided. Since the direction of the flow is in the opposite direction, the gas flow is easily separated from the liquid flow, and the flow velocity of the liquid flow slightly entering the starting end of the degassing tube becomes extremely low. Stable without foaming.

  As a result, the degassing performance of this degassing device is improved, and the differential pressure type liquid level gauge detects the differential pressure between the liquid pressure in the low-temperature liquefied gas pipe and the gas pressure in the degassing pipe with high accuracy, and detects the low temperature. The liquid level of the liquefied gas can be detected with high accuracy. Therefore, it is possible to appropriately set the gas release timing.

According to the second aspect of the present invention, the control unit that receives the detection signal of the differential pressure type liquid level meter controls the degassing control valve, thereby preventing the gas pressure in the degassing pipe from rising above a set value. be able to.

It is a lineblock diagram of a gas bleeding device for low temperature liquefied gas piping concerning an example of the present invention. It is a block diagram of the degassing apparatus for low temperature liquefied gas piping which concerns on a prior art.

  Hereinafter, embodiments for carrying out the present invention will be described based on examples.

   The present embodiment is an example in which the present invention is applied to a degassing device for an LNG pipe through which LNG as a low-temperature liquefied gas flows, and which removes LNG vaporized gas from the LNG pipe.

  As shown in FIG. 1, the LNG pipe 1 is a pipe made of low-temperature steel (for example, stainless steel). The LNG pipe 1 has a rising pipe section 2 a and a rising pipe section 2 a at a portion for removing gas generated inside. It has a gate-shaped pipe portion 2 formed in a gate shape via an upstream bent portion 2b, a horizontal straight pipe portion 2c, and a downstream bent portion 2d and a falling pipe portion 2e.

  The LNG pipe gas venting device 10 includes a downstream bent portion 2d of the LNG pipe 1, a gas vent pipe 11, a differential pressure type liquid level meter 12, a gas vent control valve 13, and a control unit 14.

The downstream bent portion 2d is formed in the LNG pipe 1 so as to change the flow direction of LNG from a horizontal direction to a downward direction.
The degassing pipe 11 is connected to the LNG pipe 1 via a rising pipe section 11a that rises upward from an upper end of a downstream bent section 2d of the LNG pipe 1, and is bent at a bending section 11b at the upper end of the rising pipe section 11a. To the horizontal tube portion 11c.
The downstream pipe wall (low temperature liquefied gas flow receiving side pipe wall) of the degassing pipe 11 in the vicinity of the downstream bent portion 2d falls, and the downstream pipe wall (low temperature liquefied gas flow receiving) of the pipe 2e. Side tube wall) so as to be linearly continuous in the vertical direction.

  The differential pressure type liquid level gauge 12 detects a pressure difference between a liquid pressure in the LNG pipe 1 and a gas pressure in the gas vent pipe 11, and transmits a liquid pressure through a sealed liquid medium to the first pressure guiding pipe 12a. And a second pressure guiding tube 12b for transmitting gas pressure via the sealed liquid medium, and a differential pressure detecting unit 12c.

  The first impulse line 12a is connected to the LNG pipe 1 at a position near the lower end of the downcomer portion 2e, and the second impulse line 12b is at a portion near the lower end of the bent portion 11b at the upper end of the riser portion 11a of the gas vent tube 12. It is connected to the. The differential pressure detecting unit 12c converts a hydraulic pressure transmitted from the first pressure guiding tube 12a and a gas pressure transmitted from the second pressure guiding tube 12b into an electric signal and outputs the electric signal to the control unit 14.

  The degassing control valve 13 is interposed in the horizontal pipe portion 11c of the degassing pipe 11. The control unit 14 controls the gas release control valve 13 in response to the detection signal of the differential pressure level gauge 12. That is, the control unit 14 opens the gas release control valve 13 for a predetermined time when the liquid level falls below a predetermined liquid level based on the detection signal of the differential pressure type liquid level meter 12, so that the gas in the pipe is removed. Prevent stagnation.

The operation and effect of the above-described LNG pipe gas venting device 10 will be described.
At the downstream bent portion 2d of the portal-shaped pipe portion 2 of the LNG pipe 1, the flow direction of LNG is changed from a horizontal direction to a downward direction. Since the degassing pipe 11 connected to the LNG pipe 1 via the rising pipe 11a rising upward from the upper end of the downstream bent portion 2d is provided, the liquid flow in the downstream bent portion 2d has a downward liquid flow and an upward liquid flow. Since the direction of the flow of the gas flow is in the opposite direction, the gas flow is easily separated from the liquid flow, and the flow velocity of the liquid flow slightly entering the starting end of the gas release pipe 11 is also extremely low, so that the gas release is performed. The liquid level in the pipe 11 is stabilized without foaming.

  As a result, the degassing performance of the degassing apparatus 10 is improved, and the differential pressure between the liquid pressure in the LNG pipe 1 and the gas pressure in the degassing pipe 11 is detected with high accuracy by the differential pressure level gauge 12. The liquid level of LNG can be detected with high accuracy. Therefore, it is possible to appropriately set the degassing timing for opening the degassing control valve 13.

  To effectively utilize the downstream bent portion 2d of the portal-shaped pipe portion 2 having the upstream bent portion 2a and the downstream bent portion 2d and formed in the gate shape, and to connect the degassing pipe 11 thereto, The manufacturing cost of the punching device 10 can be reduced. By controlling the degassing control valve 13 by the control unit 14 that receives the detection signal of the differential pressure type liquid level meter 12, it is possible to prevent the gas pressure in the degassing pipe 11 from rising above a set value.

Next, an example in which the downstream bent portion of the portal-shaped pipe portion of the LNG pipe 1 is changed will be described.
As shown in FIG. 2, a flange 4 and a blind lid 5 bolted to the flange 4 are provided at the downstream end of the horizontal straight pipe portion 3c of the gate-shaped pipe portion of the LNG pipe, and the falling pipe portion 3e Is connected so as to extend downward from a portion near the downstream end of the horizontal straight pipe portion 3c.
A downstream bent portion 3d is formed by a downstream end portion of the horizontal straight pipe portion 3c and an upstream end portion of the falling pipe portion 3e. The degassing pipe 11 of the degassing device 10A is connected to the upper end of the horizontal straight pipe 3c above the falling pipe 3e. The other configuration is the same as that of the above-described embodiment, and the description is omitted. The degassing device 10A also has the same functions and effects as the degassing device 10.

Next, an example in which the above embodiment is partially changed will be described.
(1) The case where the downstream bent portion of the portal-shaped pipe portion is used as the bent portion of the LNG pipe has been described as an example. If the bent portion changes the direction from the horizontal direction to the downward direction, the bent portion can be utilized for the gas venting device for low-temperature liquefied gas piping of the present invention.
Moreover, the angle between the axis of the horizontal straight pipe portion and the axis of the falling pipe portion is not necessarily 90 degrees, but may be an acute angle or an obtuse angle close to 90 degrees.

(2) The differential pressure type liquid level meter is an example, and it is a matter of course that various types of differential pressure type liquid level meters different from the differential pressure type liquid level meter described in the above embodiment can be adopted.
(3) In the above embodiment, the LNG pipe is described as an example of the low-temperature liquefied gas pipe. However, the low-temperature liquefied gas is not limited to LNG but may be LPG or the like.

(4) In addition, those skilled in the art can implement the present invention in a form in which various modifications are added to the embodiment without departing from the gist of the present invention, and the present invention also includes such modified forms. .

DESCRIPTION OF SYMBOLS 1 LNG piping 2 Gate-shaped piping part 2b Upstream bent part 2d, 3d Downstream bent part 10, 10A Gas release device 11 Gas release pipe
11a Rise pipe section 12 Differential pressure level gauge 13 Gas release control valve 14 Control unit

Claims (2)

In a degassing device that removes gas from a low-temperature liquefied gas pipe through which a low-temperature liquefied gas flows,
The downstream bent portion in the low-temperature liquefied gas pipe having a gate-shaped pipe portion formed in a gate shape with a riser pipe portion, an upstream bent portion, a horizontal straight pipe portion, a downstream bent portion, and a falling pipe portion,
A degassing pipe connected to the low-temperature liquefied gas pipe through a riser section that rises upward from the upper end of the downstream bent section,
A differential pressure type liquid level gauge that detects a differential pressure between the liquid pressure in the low-temperature liquefied gas pipe and the gas pressure in the gas vent pipe,
Low-temperature liquefaction characterized in that a downstream pipe wall of the degassing pipe in the vicinity of the downstream bent portion is formed so as to be linearly continuous with the downstream pipe wall of the falling pipe in the vertical direction. Gas venting device for gas piping. 2. The gas vent control valve according to claim 1, further comprising: a gas vent control valve interposed in the gas vent tube; and a control unit that receives the detection signal from the differential pressure level gauge and controls the gas vent control valve. A gas venting device for low-temperature liquefied gas piping as described.