JPH1061895A - Condensate recovering device for lng gasifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a condensate recovering device for an LNG gasifier to recover condensate gathered during waiting of the LNG gasifier and prevent the generation of high calorie gas. SOLUTION: A condensate recovering device for an LNG gasifier comprises a condensate recovering line 3 branched from a spot situated downstream from the LNG feed valve of an LNG feed line 1 and connected to a suction drum; and a condensate recovery valve arranged in the line 3. Before operation of the LNG gasifier is started, the condensate recovering valve is released to recover condensate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concentrated liquid recovery device for an LNG vaporizer used in a thermal power plant or the like using natural gas as a fuel.

[0002]

2. Description of the Related Art A thermal power plant or the like using natural gas as a fuel has an LNG base to convert natural gas into liquefied natural gas (LN).
G) and stored in a LNG vaporizer (N).
G). FIG. 2 shows an overall configuration diagram of a vaporized gas supply system (NG supply system) at the LNG terminal.
As shown in this figure, LNG is stored in an LNG tank and has an LNG pump, an LNG supply valve, and the like.
It is supplied to the LNG vaporizer through the NG supply line 1. Seawater is also supplied to the LNG vaporizer from a seawater inlet via a seawater pump, and heat is exchanged between the seawater and LNG to vaporize LNG. A general LNG base is provided with a suction drum.
LNG that evaporates naturally in the NG tank or the like is collected and separated into gas and liquid. The gas is sent to the NG supply line 4 using a compressor, and the liquid is returned to the LNG tank using a pump.

[0003] The LNG vaporizer used here includes:
A so-called open rack type is adopted, and its conceptual diagram is shown in FIG. 3A, and its entire side view is shown in FIG.
It is shown in (B). As shown in FIG. 3 (A), the open rack type vaporizer includes an upper header, a lower header, a heat transfer tube portion communicating with the upper header and the lower header, a fin portion provided between the heat transfer tube portions, a seawater pipe, It has a trough for discharging seawater and a receiving tank for receiving the discharged seawater. LN
G is supplied into the lower header, and the seawater is discharged from the seawater pipe through the trough so as to form a seawater film on the heat transfer tube portion and the fin portion. Then, the LNG is heated by the seawater and vaporized, and becomes a vaporized gas (NG) and rises to the upper header. When it is actually used as a vaporizer, a plurality of lower headers are connected in parallel so as to be parallel. FIG.
As shown in (B), the plurality of lower headers have LNG.
LNG is supplied from the inlet pipe, and seawater is supplied to the seawater pipe from the seawater inlet pipe. On the other hand, vaporized gas (N
G) is collected and discharged from a plurality of upper headers to an NG outlet pipe.

[0004]

In the above-mentioned LNG vaporizer, the intermittent operation is performed according to the necessity of the supply destination of the vaporized gas, and the supply amount is adjusted by the LNG supply valve. Therefore, if LNG is suddenly supplied when the operation of the LNG vaporizer is restarted, since LNG is extremely low at -162 ° C, it is rapidly cooled from the line 1 downstream of the LNG supply valve to the LNG vaporizer. Become. This LNG vaporizer and L
In the connection portion of the NG supply line 1, the piping on the LNG supply line 1 side is so-called stainless steel, and the LNG vaporizer side is aluminum, which is different in material. Therefore, when the connection portion is rapidly cooled as described above, the flange of the connection portion is opened due to a difference in thermal conductivity, and there is a possibility that LNG leaks. Therefore, as shown in FIG. 2, a bypass line 2 having a temperature control valve is provided from the upstream side to the downstream side of the LNG supply valve, and when the temperature of the LNG vaporizer rises to a certain temperature, the temperature control valve is opened. A small amount of LNG is supplied to the LNG vaporizer and cooled.

[0005] LNG supplied for cooling is LNG.
Even if the vaporizer is not operating, it evaporates gradually. By the way, natural gas is a gas mainly composed of methane that is naturally generated from oil fields and coal mines, but also contains hydrocarbons such as ethane, propane, butane, and pentane, which have more carbon atoms than methane. . In general, hydrocarbons have a property that the lower the number of carbon atoms, the more easily they evaporate, and the more the number of carbon atoms, the more difficult it is to evaporate. Therefore, L
LNG supplied for cooling during standby of the NG vaporizer is concentrated as the standby time becomes longer, resulting in a high calorie concentrate. In this state, when the operation of the LNG vaporizer is restarted, the concentrated liquid is temporarily vaporized,
High calorie gas is supplied to power plants. Then, at the vaporized gas supply destination, there is a problem that the normal calorific value range is exceeded, the gas is detected as abnormal, and the gas stops.

The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a concentrated liquid recovery device for an LNG vaporizer that collects concentrated liquid accumulated during standby of the LNG vaporizer and prevents generation of high-calorie gas.

[0007]

[Means for Solving the Problems]

According to the present invention, heat exchange is performed between liquefied natural gas supplied from an LNG tank storing liquefied natural gas through an LNG supply line having an LNG supply valve and seawater, and the liquefied natural gas is vaporized gas. LN discharged as
A concentrate recovery device for a G vaporizer, comprising: a concentrate recovery line branched from a downstream side of the LNG supply valve of the LNG supply line; and a concentrate recovery valve provided in the line, Before starting operation of the LNG vaporizer, the concentrated liquid recovery valve is opened to recover the concentrated liquid, and a concentrated liquid recovery apparatus for the LNG vaporizer is provided.

[0009] The present invention described above uses the LNG tank to convert
A concentrated liquid recovery line having a concentrated liquid recovery valve is provided in the LNG supply line for supplying LNG to the G vaporizer, and the valve is opened and closed to collect the concentrated liquid accumulated between the LNG supply valve and the LNG vaporizer. Is what you do. That is, the concentrate recovery valve is opened only before the operation is started from the standby state, and the concentrate collected between the LNG supply valve and the LNG vaporizer flows through the concentrate recovery line to be collected. . Therefore, even if the concentrated liquid accumulates due to a long standby time, high calorie gas is not generated when the operation of the LNG vaporizer is restarted.

Further, according to the embodiment of the present invention, the concentrated liquid recovery line is connected to a suction drum connected to the LNG tank, and the suction drum separates the concentrated liquid into gas and liquid and separates the gas component. It is preferable that the gas is discharged as a vaporized gas and the liquid component is sent back to the LNG tank.

The above-described embodiment of the present invention aims to make effective use of the collected concentrate. That is, LNG
Focusing on the fact that a suction drum having a gas-liquid separation function is provided at the base, a concentrated liquid recovery line is connected to the suction drum, and the concentrated liquid is separated into vaporized gas and LNG. With this configuration, the concentrated liquid can be processed without the need to provide a special device or the like.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. FIG. 1 shows the LNG of the present invention.
1 is an overall configuration diagram of an NG supply system including a concentrated liquid recovery device of a vaporizer. The NG supply system shown in this figure has basically the same configuration as the conventional NG supply system shown in FIG. 2, and includes an LNG supply line 1, an LNG supply valve, a suction drum, an LNG vaporizer, an LNG tank, and a temperature control valve. , NG supply line 4 and the like. In addition, vaporized gas (NG) such as turbine
Are not shown.

According to the present invention, a concentrated liquid recovery line 3 branched from the downstream side of the LNG supply valve of the LNG supply line 1 and connected to a suction drum, and a concentrated liquid recovery valve provided in the line 3 are provided. Before starting operation of the LNG vaporizer, the concentrate recovery valve is opened to collect the concentrate,
The concentrated liquid is separated into gas and liquid by a suction drum, the gas is discharged as a vaporized gas using a compressor, and the liquid is returned to an LNG tank using a pump.

Here, the LNG vaporizer is provided with an LNG pump from an LNG tank for storing liquefied natural gas (LNG),
Heat exchange is performed between LNG supplied through an LNG supply line 1 having an LNG supply valve and the like and seawater supplied from a seawater inlet via a seawater pump or the like, and the LNG is discharged as a vaporized gas (NG). (See FIG. 3 for details).

The LNG supply line 1
A bypass line 2 having a temperature control valve is provided from the upstream side to the downstream side of the NG supply valve, and a small amount of LNG is supplied to the LNG vaporizer side during standby to cool the LNG vaporizer. The concentrate recovery line 3 is for collecting the concentrate collected in the LNG vaporizer (specifically, the lower header or the manifold).
The efficiency is better near the NG entrance. Therefore, as shown in FIG. 1, it is preferable that the concentrate recovery line 3 is branched from the downstream side of the bypass line 2.

Further, a suction drum is provided at the LNG base, and LNG which evaporates naturally in the LNG tank or the like is collected and separated into gas and liquid, and the gas is sent to the NG supply line 4, and the liquid is sent to the LNG tank. Back to. Focusing on the function of the suction drum, in the present invention, the concentrated liquid recovery line 3 is connected to the suction drum to separate the concentrated liquid into gas and liquid. By constructing the line in this manner, the concentrated liquid can be recovered, and the concentrated liquid can be processed using the existing equipment without providing a special device. By gas-liquid separation of the liquid into vaporized gas (NG) and LNG, it is possible to effectively use resources without waste.

Next, the operation of the present invention will be described with reference to FIG. As described above, the LNG vaporizer provided in a thermal power plant or the like operates intermittently according to the amount of vaporized gas supplied. Therefore, (1) during normal operation, (2)
The following description focuses on the opening and closing of each valve during standby and (3) when restarting operation.

(1) Normal operation The LNG supply valve provided in the LNG supply line 1 is open, and LNG is continuously supplied from the LNG tank to the LNG vaporizer. At this time, the temperature control valve provided in the bypass line 2 and the concentrated liquid recovery valve provided in the concentrated liquid recovery line 3 are closed so that LNG does not flow.

(2) Standby When a standby command is issued from the vaporized gas supply destination, the LNG supply valve is closed and the supply of LNG to the LNG vaporizer is stopped. The temperature control valve is operated by a thermometer or a temperature control device (not shown) connected to the LNG vaporizer. Then, when the temperature of the LNG vaporizer becomes higher than a predetermined temperature, the temperature control valve is opened, and a small amount of LNG is supplied to the LNG vaporizer through the bypass line 2 to cool the LNG vaporizer. Note that the concentrate recovery valve is kept closed.

(3) Resumption of Operation When the operation starts from the vaporized gas supply destination, the temperature control valve is closed and the concentrated liquid recovery valve is opened. In general, the concentrated liquid tends to accumulate as the standby time becomes longer. For example, the standby liquid may be opened when the predetermined time has exceeded a predetermined time, and may not be opened when the standby time has not been exceeded. May be opened. By opening the concentrate recovery valve, the concentrate accumulated in the LNG vaporizer is circulated through the concentrate recovery line 3 to the suction drum. Then, after confirming that the concentrate has run out, the concentrate recovery valve is closed, the LNG supply valve is opened, and the operation of the LNG vaporizer is restarted. here,
In opening and closing the concentrate recovery valve, the opening and closing time of the concentrate recovery valve is determined in advance from the relationship between the standby time and the degree of accumulation of the concentrate and the concentrate recovery capability of the concentrate recovery valve and the concentrate recovery line 3. You may do so. Thus, LNG
By collecting the concentrated liquid before restarting the operation of the vaporizer, a stable supply of energy can be achieved without temporarily supplying high-calorie gas to the vaporized gas supply destination.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0022]

According to the above-described concentrated liquid recovery apparatus for an LNG vaporizer of the present invention, the concentrated liquid collected in the LNG vaporizer can be recovered by providing the concentrated liquid recovery line having the concentrated liquid recovery valve. When the operation of the LNG vaporizer is restarted, high-calorie gas is not generated, and stable energy can be supplied. In addition, since the concentrated liquid recovery line is connected to the suction drum, the concentrated liquid can be treated without providing a special device, etc., and effective use of resources without waste can be achieved. Has an effect.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an NG supply system including a concentrated liquid recovery device for an LNG vaporizer according to the present invention.

FIG. 2 is an overall configuration diagram of an NG supply system in an LNG base.

FIG. 3 shows an open rack type LNG vaporizer,
(A) is a conceptual view thereof, and (B) is an overall side view thereof.

[Explanation of symbols]

 1 LNG supply line 2 Bypass line 3 Concentrate recovery line 4 NG supply line

Claims (2)

[Claims] 1. An LNG for performing heat exchange between liquefied natural gas supplied from an LNG tank storing liquefied natural gas through an LNG supply line having an LNG supply valve and seawater, and discharging the liquefied natural gas as a vaporized gas A concentrate recovery device for a vaporizer, comprising: a concentrate recovery line branched from the LNG supply line downstream of the LNG supply valve; and a concentrate recovery valve provided in the line. A concentrated liquid recovery device for an LNG vaporizer, wherein the concentrated liquid recovery valve is opened to recover a concentrated liquid before starting operation of the LNG vaporizer. 2. The concentrated liquid recovery line is connected to a suction drum connected to the LNG tank. The suction drum separates the concentrated liquid into gas and liquid, discharges a gas component as a vaporized gas, and discharges the liquid component into the gas. The concentrated liquid recovery device for an LNG vaporizer according to claim 1, wherein the concentrated liquid recovery device is adapted to be sent back to the LNG tank.