JP4181250B2 - Natural gas heating method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, for example, a natural gas which is cold utilized from liquefied natural gas is vaporized to above the boiling point, mixing the liquefied natural gas that is not cold utilized simultaneously vaporized natural gas by open rack vaporizer for raising the temperature relates to a heating method, the upper header tank of the open rack vaporizer without a down flow type and a double tube, the liquid in Supajipaipu, the configuration for supplying gas to the header annulus, the conventional respective liquid and gas The present invention relates to a natural gas temperature raising method using a downflow type open rack type vaporizer that can efficiently vaporize and raise the temperature of one that requires a heat exchanger.
[0002]
[Prior art]
As a vaporizer for liquefied natural gas (hereinafter referred to as LNG), a vaporizer such as an open rack vaporizer (ORV) or a submerged vaporizer (SMV) is used. In order to heat natural gas (hereinafter referred to as NG), brazing heaters, hot water heaters and the like have been used.
[0003]
An open rack type carburetor that is frequently used as an LNG vaporizer is, for example, a fin-like tube with a pair of fins projecting in the diameter direction to form a single panel, and a header tank at the upper and lower ends. To form a heat exchange panel, a plurality of the panels are arranged in a row, LNG is introduced from the lower header tank to raise the inside of the heat exchange panel, and the sea water of the heat medium is supplied from the watering trough disposed above. It is a structure for exchanging heat while flowing down the surface of the heat exchange panel.
[0004]
In addition, the open rack type vaporizer also has a down flow type structure that leads out from the upper part to the lower part. The LNG is led to the sparge pipe installed in the upper header tank, and the LNG is continuously distributed evenly from the small holes provided in this. By being ejected, it was introduced into the annular passage portion of the header and was evenly distributed to the heat transfer tubes.
[0005]
[Problems to be solved by the invention]
Since LNG itself has an extremely low temperature (−160 ° C.), various utilization of this cold energy is performed, and for example, it is used as a cold heat source for large refrigerators and refrigerators. In this case, LNG is vaporized by a heat exchanger such as a refrigerator, and becomes NG of about −40 ° C., for example. In order to use this NG as a fuel, it is necessary to further raise the temperature to room temperature, and the temperature is separately raised by the above-mentioned ORV or the like. However, about several percent of the NG may still contain LNG, However, since it is difficult to disperse more uniformly than the problem of gas-liquid two-phase flow, there are problems that abnormal noise and vibration are generated during operation, and stable vaporization cannot be performed.
[0006]
When mixing and vaporizing and heating both NG and LNG with one ORV, a mixing device is provided in the piping part immediately before the introduction of the vaporizer, and if it is introduced into the sparge pipe in a gas-liquid mixed phase state, the liquid / Gas separation occurs, and it becomes a wavy flow or a lump flow in the sparge pipe and cannot be distributed without any bias.
[0007]
On the other hand, if NG and LNG are separately introduced into the header tank without passing through the sparge pipe, the liquid / gas separation due to the difference in specific gravity shows the same aspect as described above, and the heat transfer tubes cannot be evenly distributed.
[0008]
In addition, when NG and LNG are separately introduced into the header, NG is cooled by LNG that is extremely cold inside, and part or most of it may be reliquefied. Since contraction (generally, the volume ratio of liquid to gas is 1: 600), the shock causes the liquid to oscillate inside the header, generating abnormal noise and vibration, causing a great amount of stress to the device, So-called tilts such as unstable gas pressure at the outlet and flow rate hunting appear, and there is a problem that it cannot be used for normal operation.
[0009]
Therefore, gaseous NG that has been cold-utilized in the refrigerator or the like has been heated or vaporized by another ORV or the like by removing LNG with a gas-liquid separator. Accordingly, when viewed from the whole apparatus, there is a discomfort for requiring a plurality of vaporizers to increase the size.
[0010]
This invention eliminates problems inherent to gas-liquid two-phase flow and problems due to reliquefaction when mixing and vaporizing both NG and LNG with one ORV as described above. According to without, the vaporized gas pressure is stabilized on the outlet side, without problems flow hunting, efficiency both NG and LNG in a single heat exchanger may, vaporization, of possible down-flow type be heated ORV The purpose is to provide a method for raising the temperature of natural gas.
[Means for Solving the Problems]
The inventors have conducted various studies on the configuration of the header tank in order to eliminate the problems specific to gas-liquid two-phase flow of vaporized gas and liquefied gas and the problem due to reliquefaction in ORV. Knowing that the purpose can be achieved by adopting a down-flow type open rack type vaporizer that supplies liquefied gas to the sparge pipe and vaporized gas to the header ring and lowers it to the lower header tank to exchange heat. did.
[0012]
In addition, in the ORV configured as described above, the inventors have provided a small hole for supplying a liquefied gas on the upper surface of the sparge pipe, and provided a ring for preventing a blowing flow on the outer periphery of the sparge pipe, By arranging rectification means in the upper header tank to rectify the turbulence immediately after the gas flows into the header, the gas-liquid two-phase mixing in the header is made uniform, and gas re-liquefaction is performed in the header. Thus, the present invention has been completed by discovering that heat is distributed to the heat transfer tubes without uneven flow, heat exchange in each heat transfer tube is uniform, and smooth vaporization is possible.
[0013]
Further, the inventors can apply any vaporized gas and liquefied gas to the downflow type ORV having the above-described configuration, for example, gaseous NG using cold heat, boil-off gas generated during storage in a tank, cargo handling, etc. The boil-off gas generated therein can be mixed and vaporized with normal liquefied NG, and in particular, the vaporized gas is NG, and the liquefied gas is the same LNG or liquefied petroleum gas LPG for heat quantity adjustment, etc. It was confirmed that the application example was suitable.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
A configuration example of the ORV of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an overall configuration of an ORV according to the present invention. A heat exchange panel 1 is formed as a single panel by arranging fin tubes 2 with a pair of fins protruding in the diameter direction in the fin direction. The header tanks 3 and 4 are provided at the ends, and the sea water of the heat medium is caused to flow down to the surface of the heat exchange panel 1 from the watering trough 5 disposed above the heat exchange panel 1.
[0015]
As shown in FIG. 2, the upper header tank 3 has a double pipe structure in which a sparge pipe 33 is built in an outer pipe 31 closed at both ends. Here, the sparge pipe 33 is connected to a liquefied gas introduction port 34 from one end of the outer pipe 31. A vaporized gas inlet 32 is provided on the upper surface of the outer tube 31 on the same side.
[0016]
The other end of the sparge pipe 33 is closed and supported by a blind flange 35 fitted into the outer pipe 31 as shown in FIG. 3C, and a wing provided radially between the introduction port 34 and the inlet 34 as shown in FIG. 3A. Are supported by the supports 36 and 37. The inside of the outer tube 31 is composed of a sparge pipe 33 and its annular portion. Further, the support can be provided in various configurations such as protruding from the outer peripheral portion of the sparge pipe 33 or the inner peripheral portion of the outer tube 31 or being inserted into the annular portion by another member.
[0017]
Among the supports, the support 37 close to the vaporized gas introduction port 32 of the outer pipe 31 is set to have a long wing width here, and the vaporized gas that has entered the annular portion of the upper header tank 3 travels around the outer periphery of the sparge pipe 33. It also serves as a rectifying / distributing plate that rectifies so as to prevent and move parallel as much as possible.
[0018]
The rectifying means for rectifying the turbulence immediately after the vaporized gas flows into the header tank 3 and distributing the vaporized gas evenly in the annular portion is the radial wing also used as a support, the outer periphery of the sparge pipe 33 or the inner periphery of the outer pipe 31. Various configurations can be adopted as long as rectification is possible, such as a small wing projecting from the portion, a rib-like shape, or a separate member inserted into the annular portion.
[0019]
On the other hand, small holes 38 are provided on the upper surface of the sparge pipe 33 at regular intervals, and the liquefied gas introduced into the sparge pipe 33 overflows from the small holes 38. In addition, a ring 39 is provided on the outer periphery of the sparge pipe 33 for each predetermined number of small holes 38, and this causes the liquefied gas overflowed by the vaporized gas that travels in an annular portion parallel to the outer periphery of the sparge pipe 33 to flow. It has a function to prevent.
[0020]
In the upper header tank 3 having the above-described configuration, the vaporized gas that has entered the annular portion of the upper header tank 3 is evenly distributed in the annular portion by the support 37 that also serves as a rectifying and distributing plate, and proceeds along the sparge pipe 33. Further, the liquefied gas introduced into the sparge pipe 33 overflows from the small hole 38 on the upper surface of the pipe, and the vaporized gas and the liquefied gas flow down the annular portion while being mixed and reliquefied, and are connected through the upper header tank 3. Reaches the upper end 21 of the fin tube 2 and flows down in the fin tube 2.
[0021]
In particular, in the ring 39 provided on the outer periphery of the sparge pipe 33, the liquefied gas ejected from the small hole 38 is not blown in the longitudinal direction by the vaporized gas but falls downward on the ring 39 so that a large number of fin tubes 2 are provided. It is possible to prevent unequal distribution to
[0022]
Depending on the mixing ratio of the liquefied gas and the vaporized gas, the vaporized gas does not re-liquefy. However, at this time, it is mixed and flows down at the upper end portion 21 of the fin tube 2 and is exchanged with seawater in the fin tube 2 for vaporization and heating. Then, everything is converted into gas, led out from the lower header tank 4 and supplied to the consumer.
[0023]
In the present invention, the ORV of any heat source and configuration can be used for the ORV of the heat exchanger as long as a downflow configuration in which the characteristic upper header tank is a double pipe can be adopted. In addition, a known dissimilar metal joint is used at the inlet of the liquefied gas and the vaporized gas to prevent leakage, or by covering the outside of the upper header tank with a heat insulating material and keeping it cool, the heat exchange efficiency is stabilized and improved. It is also possible to employ known auxiliary means.
[0024]
【Example】
When LNG was vaporized with a heat exchanger as a cooling heat source of the refrigerator with the preceding stage and a downflow ORV having the above-described configuration was used with the latter stage, NG of about −40 ° C. was obtained in the preceding stage. The NG and LNG were supplied to the downflow type ORV according to the present invention to be mixed and vaporized, and the operation for obtaining normal temperature NG was continuously operated for 6 months or more.
[0025]
During the test, there was no abnormal noise or vibration during operation, there was no tilt, the vaporized gas pressure on the outlet side was stable, and the design value operation was possible. When the time-dependent change of each part was investigated, it turned out that it has extremely high durability.
[0026]
That is, gas-liquid mixing in the upper header tank is made uniform, and gas reliquefaction is continuously performed in the tank, so that it is distributed to the tubes without uneven flow, heat exchange in each tube becomes even, extremely Smooth vaporization is performed, and since the inflow of each tube is uniform and there is no temperature variation, the tube as a panel can prevent abnormal stress due to difference in shrinkage, bend, etc., straight state As a result, it is presumed that the device can be made highly durable.
[0027]
【The invention's effect】
Natural gas heating method according to the down flow type ORV of the invention, without emitting noise and vibration without oscillating due to wavy flow or bulk flow due to the gas-liquid two-phase flow in the upper header tank, the gas-liquid Because mixing is performed uniformly and gas reliquefaction is continuously performed in the upper header tank, distribution to each tube and heat exchange are performed uniformly, and the inflow is uniform and there is no temperature variation. , the durability of the device it is possible to perform efficient heat exchange can be highly Mel.
[0028]
The downflow ORV according to the present invention is a natural liquefied natural gas that is obtained by using cold natural gas, boil-off gas generated during storage in a tank, boil-off gas generated during cargo handling, etc. At the same time, mixing, vaporization, and heat treatment are possible with a single device.
[Brief description of the drawings]
FIG. 1 is an explanatory front view showing the overall configuration of a downflow type open rack type vaporizer according to the present invention.
FIG. 2 is a longitudinal sectional view showing an internal configuration of an upper header tank of a downflow type open rack type vaporizer according to the present invention.
3 is a longitudinal sectional view showing details of a main part of the upper header tank of FIG. 2, wherein A is a cross section in the diameter direction of the tank, B is a cross section in the axial direction of the tank, and C is a cross section of the tank end.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heat exchange panel 2 Fin tube 3 Upper header tank 4 Lower header tank 5 Watering trough 21 Upper end port 31 Outer tube 32 Vaporized gas inlet port 33 Sparge pipe 34 Liquefied gas inlet port 35 Blind flange 36, 37 Support 38 Small hole 39 Ring

Claims (4)

The upper header tank of the downflow type open rack type vaporizer is made into a double pipe, and the liquefied natural gas to be vaporized is supplied to the header annular part outside the sparge pipe through the inside sparge pipe and vaporized from the liquefied natural gas. and was fed directly to the low temperature of the natural gas to the header annulus than room, is lowered into the lower header tank to heat exchange, natural gas heating method according to the down flow type open rack vaporizer. 2. The natural gas heating method according to claim 1 , wherein a small hole for supplying liquefied gas is provided on the upper surface of the sparge pipe, and a ring for preventing a blown flow is provided on the outer periphery of the sparge pipe. natural gas heating method according to the rack-type vaporizers. In the natural gas heating method according to claim 1, the vaporized gas is due to down-flow type open rack type vaporizer which rectifying means is disposed in the upper header tank for rectifying the disturbance immediately after flowing into the header natural gas heating method. 2. The natural gas temperature rising method according to claim 1 , wherein the natural gas having a temperature lower than room temperature is vaporized to a boiling point or higher by using cold heat from liquefied natural gas .

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