JPS608439B2 - Improvement of shell-and-tube heat exchanger - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in shell-and-tube heat exchangers.

More specifically, the present invention relates to an improvement in preventing fluid leakage in a heat exchanger for vaporizing liquefied natural gas (LNG). Conventionally, a U-tube type multi-tube heat exchanger is generally used as an LNG vaporizer.

In the carburetor, flange fixing is usually used to fix the fixed tube plate, the partition chamber, and the shell, as in the case of conventional ones. By the way, the design pressure of LNG, which is the pipe side fluid, is generally set at 70k9/mG or higher, and in addition, given the recent efforts to increase the vaporization capacity of LNG, the above-mentioned flange fixing is not sufficient. LNG leakage from these parts has become a problem. The present invention first solves the above problems, and its first feature is that the pipe side fluid is water or seawater, and the pipe side fluid is water or seawater. A heat exchanger for vaporizing liquefied natural gas, which is an intermediate heat medium in which the fluid on the shell side is condensed by liquefied natural gas and vaporized by water or seawater in a shell that accommodates both. , the fixed tube plate of the east side of the U-shaped pipe is integrally fixed to this in the partition chamber, and the end of the partition that protrudes outward from the fixed tube plate is fixed to the end of the body by a flange. be.

Next, an example of the present invention will be specifically described with reference to the accompanying drawings.

1 is a partition chamber, 2 is a partition plate thereof, and there is a U inside the chamber.
A fixed tube plate 4 having a cross section 3 is integrally fixed by welding.

A flange 5 is attached to the end of the partition 1 that projects outward from the fixed tube plate 4. Reference numeral 6 denotes a body, and a flange 7 is attached to the end opposite to the flange 5, and both flanges are fixed.

The illustrated heat exchanger is for LNG vaporization, and the LNG supplied from the lower partition is heated and vaporized by the body side fluid (propane is used in this example) in the U-shaped pipe east 3, and then It is of the type that can be taken out from the partition room.

In addition, in the lower part of the body 6, another pipe 8 is arranged, adopting the structure of a fixed tube sheet type multi-tube heat exchanger, and water is supplied as a pipe side fluid through partitions 9 and 10 on both sides. Or seawater is flowing. Therefore, the propane condensed and liquefied by LNG in the upper U-shaped pipe East 3 is transferred to the lower U-shaped pipe East 8.
The LNG is then heated and vaporized by LNG, and then used again for LNG heating and vaporization. Furthermore, this specific example has a structure in which another fixed tube sheet type multi-tube heat exchanger is attached, in which the partition chamber 9 is configured as a common partition chamber. The Kanto East 1
1 is supplied with the water or seawater from the outside from one partition 12. On the other hand, the arm side fluid is used to further salt the vaporized natural gas taken out from the upper part of the partition chamber 1. In such a configuration, the design pressure of the shell-side fluid is determined depending on the type of fluid, but for example, when propane is used for heating and vaporizing LNG, it is 15.6 kg/kg.
It is.

Further, the pressure during normal operation in this case is determined by the LNG load, the flow rate and temperature of the heating fluid of water or seawater, and is approximately 8.0 k9/lump G at the maximum operating pressure.
Therefore, the pressure on the LNG side can be dealt with by integrally fixing the fixed tube plate 4 inside the partition chamber 1.
In addition, pressure on the propane side can be dealt with by fixing the flanges of the partition chamber 1 and the shell 6, so that the pressure on the propane side can be prevented from leaking from the heat exchanger, and the large size of the device can be make it easier to A second feature of the present invention is that a receiving tray 21 is disposed below the pipe east 3 in contact with and close to the fixed tube plate 4, and a dispersion pipe 22 is connected to this to form a supercooled liquefaction pipe. The bread is received in a saucer 21 and distributed through a dispersion pipe 22 into the shell. As approximately 150 qo of LNG flows through the tube 3 and vaporizes, the outer surface of the tube 3 in contact with and in close proximity to the fixed tubesheet 4 is cooled to -70 to 180 qo.

Therefore, the amount of propane that is condensed and liquefied in this area is 140q.
It is cooled down to near o. On the other hand, since propane, which is an 8-ipsilateral fluid, is generally operated at -10 to 0°C as a whole,
Only the lower part of the flange parts 5, 7 is locally very cooled by contact with said subcooled liquefied propane, so that propane can leak out of said part during operation due to thermal contraction of said part. According to the second feature, the supercooled liquefied propane is stored in the saucer 21 and the dispersion pipe 2
2, the propane is sprayed appropriately within the same month, so the propane is prevented from coming into direct contact with the flange parts 5 and 7, preventing local cooling of the parts, and thus preventing the propane from coming into direct contact with the flange parts 5 and 7. It becomes possible to prevent leakage to the outside. According to the present invention comprising the above first and second features, by using cryogenic high-pressure LNG and by supercooling the intermediate heat medium by LNG, the fixed tube sheet, the partition room, and the moon can be connected to each other. It is possible to prevent LNG and intermediate heat medium from leaking to the outside from the flange fixing part.

[Brief explanation of drawings]

Fig. 1 is a simplified sectional view showing an example of the heat exchanger of the present invention;
The figure is an enlarged and simplified sectional view of the main parts, 1 is a partition room,
3 is a U-shaped tube, 4 is a fixed tube plate, 5 and 7 are flanges, 6 is a body, 21 is a saucer, and 22 is a dispersion tube. Figure 1 Han 2 Kyo

Claims (1)

[Claims] 1 It has a U-shaped tube bundle in the upper part where the tube side fluid is liquefied natural gas, and has another tube bundle in the lower part where the tube side fluid is water or seawater, and in the shell that accommodates both, the body side fluid is liquefied natural gas. In a heat exchanger for vaporizing liquefied natural gas, which is an intermediate heat medium that is condensed by gas and vaporized by water or seawater, a fixed tube plate of a U-shaped tube bundle is integrally fixed thereto in a partition, The end of the partition projecting outward from the fixed tube sheet is fixed to the end of the body by a flange, and a saucer is disposed below the U-shaped tube portion that is in contact with and close to the fixed tube sheet. An improvement characterized in that a dispersion pipe is connected to the container to receive the supercooled liquefied intermediate heat medium in the receiving tray, and the supercooled liquefied intermediate heat medium is distributed into the shell through the dispersion pipe.