JPH0633866B2 - Decompression boiler type vaporizer - Google Patents

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decompression boiler type vaporizer for vaporizing liquefied natural gas (hereinafter referred to as LNG), and in particular, a boiler section and a condensation chamber are separately arranged, and a non-condensable gas is provided in the condensation chamber. The present invention relates to a decompression boiler type vaporizer in which a removal section is provided to prevent deterioration of heat exchange performance due to generation of non-condensable gas.

[Prior art]

As an LNG vaporizer, an open rack type vaporizer has been put into practical use, which uses seawater as a heat medium to sprinkle water on a heat transfer tube configured in a vertically arranged panel shape to elevate and vaporize LNG. Also, as a vaporizer using burner combustion heat as a heat source,
There is an underwater combustion type. This is because the high-temperature combustion gas generated by the underwater combustion burner is guided below the heat exchanger for vaporizing LNG immersed in the water tank and ejected into the water, and the temperature of the LNG is raised and vaporized using water as an intermediate heat medium. Become. In such an underwater combustion method, due to the influence of moisture in the water tank,
Burner ignition failure is likely to occur, and a severe circulating water flow is dealt with, so the heat exchanger structure becomes complicated and expensive, and in order to generate and maintain the circulating water flow, there are problems such as excessive capacity of the blower and electric motor. there were. In addition, a decompression boiler is put into practical use as one that utilizes burner combustion heat (Japanese Patent Publication No. 52-47083, Japanese Patent Laid-Open No. 62-245003
No., Japanese Patent Publication No. 62-2667). As shown in FIG. 2, this is a depressurized can body that contains water (2) as a heat medium and has a predetermined depressurized atmosphere inside the can body.
(1) and a burner (3) installed at the bottom of the can body where water has accumulated
Burner tube (4) for transferring the combustion heat of
Comprised of heat transfer tubes (5) arranged in the upper space of (1),
The water (2) heated by the burner tube (4) boils under reduced pressure to generate steam, and the heat transfer tube is generated by the condensation heat transfer of this steam.
It has the effect of raising the temperature of the fluid in (5) and is often used as a hot water boiler for water supply and heating. [Problems to be Solved by the Invention] When the decompression boiler having the above configuration is used as a vaporizer for a low temperature fluid such as LNG, performance deterioration due to the generated non-condensable gas is particularly remarkable. That is, noncondensable gas
If it adheres to the surface of (5), it will flow in the heat transfer tube (5) with steam.
The heat transfer performance with LNG was significantly reduced, and abnormal ice accretion occurred on the surface of the heat transfer tube (5) where a large amount of gas had adhered, causing heat transfer tube (5)
Ice accretion on the surface further impedes heat transfer between steam and LNG,
Has a problem that it is not completely vaporized and is supplied to the outside as a gas in which a low temperature liquid component is mixed. Therefore, in the decompression boiler type carburetor having the above structure, in order to remove the non-condensable gas generated inside, it is necessary to extract the gas using the vacuum pump (7). According to the present invention, in the decompression boiler type carburetor, effective vacuum bleeding can be performed by the vacuum pump at the time of operation, so that non-condensable gas can be prevented from adhering to the heat transfer tube and vaporization performance due to non-condensable gas is less deteriorated The purpose is to provide a decompression boiler type vaporizer consisting of. Means for Solving the Problem The present invention is a sealed and decompressed lower part of a can body in which a burner tube for transferring the combustion heat of a combustion burner is arranged, and water is retained in the lower part of the can body including the same part. Between the decompression boiler part where the upper space of the can is the steam chamber and the condensation chamber part where the heat transfer tube bundle where liquefied natural gas flows is installed, the inlet pipe for introducing steam from the steam chamber and the non-condensation of the condensation chamber Condensed water return pipe that connects the lower part of the characteristic gas removal part and the lower part of the can is arranged, and a plurality of heat transfer tube bundles in the condensation chamber are made to protrude longer than other heat transfer tubes, and It is a decompression boiler type vaporizer characterized in that a non-condensable gas removing part for collecting the is provided. Effect This invention is a vaporizer for low-temperature fluid such as LNG, which is a decompression boiler type, and has a configuration in which individual decompression boiler sections and condensation chamber sections are connected by piping to prevent boiling vibration and unnecessary NG temperature rise due to low load. In addition, a part of the heat transfer tube bundle arranged in the condensing chamber part is extended so that the steam from the steam introducing pipe flows through the heat transfer tube bundle to the extended U-shaped tube portion, Since the non-condensable gas is collected in the portion, the non-condensable gas does not stay in the remaining heat transfer tube portion, only the original heat exchange is possible, and the deterioration of the heat transfer performance can be prevented. Further, the gas body accumulated in the non-condensable gas removing section may be discharged to the outside in an appropriate time cycle, and during this cycle, most of the heat transfer tubes in the heat transfer tube bundle can mainly perform heat exchange, Stable heat exchange is possible without deterioration of heat transfer performance. First Embodiment FIG. 1 is a circuit diagram showing the structure of a decompression boiler type carburetor according to the present invention. In the drawings, the heat transfer tube bundle is shown as a single tube for easy understanding. The decompression boiler type carburetor shown in FIG. 1 is composed of a decompression boiler section (10) and a condensation chamber section (20) which are connected by piping, and water (2) as a heat medium is contained in the decompression boiler section (10). In order to store and make the inside of the can atmosphere a predetermined body pressure or less, it is possible to adopt a method in which air is extracted while heating and then sealed to form a reduced pressure atmosphere, or a vacuum pump is connected and arranged. Also, in the lower part of the can body where the water in the decompression boiler section (10) has accumulated,
Burner tube for transferring the combustion heat of the burner (11) to water
(12) is provided. For the burner tube (12), any known configuration such as an exhaust gas reversal type in which combustion gas makes a U-turn can be applied. Further, the fuel system of the burner (11) is provided with a fuel control valve whose opening and closing is controlled by a thermometer arranged in the steam chamber, and the combustion state of the burner (11) is adjusted. The condensation chamber section (20), which is composed of a sealed can that is separate from the decompression boiler section (10), is connected to the steam chamber, which is the upper space in the boiler section (10), by the steam introduction pipe (21), Further, the lower part of the non-condensable gas removing part (22) of the condensing chamber part (20) and the lower part of the pressure reducing boiler part (10) are connected by a condensed water return pipe (23), which is similar to the pressure reducing boiler part (10). There is no depressurized atmosphere, and there is
A heat transfer tube bundle (30) through which LNG flows is arranged. The heat transfer tube bundle (30) in the condensation chamber section (20) is connected to the LNG heat transfer tube (5) via a control valve, and the steam introduced into the room causes L
NG is heated and evaporated. Here, the heat transfer tube bundle (30) has a configuration in which a large number of U-shaped tubes of the same size are arranged in parallel, and a part of the heat transfer tube bundle in which the U-shaped tube portion is projected longer than other heat transfer tubes is used. Form a heat transfer tube (31) for removing the non-condensable gas. The arrangement method of the heat transfer tubes (31) for removing the non-condensable gas is
Any of (30) may be used, and it is optional such as arranging at regular intervals. The condensing chamber section (20) has a heat transfer tube (3
A non-condensable gas removing section (22) is provided in which a portion where 1) projects from the heat transfer tube bundle (30) is a separate chamber. In such a configuration, the combustion heat of the burner (11) heats the water (2) through the burner pipe (12), and the water (2) boils under reduced pressure to become steam, which is condensed through the steam introduction pipe (21). Room
Introduced in (20), heat transfer tube bundle by condensation heat transfer of water vapor
The fluid in (30) has the effect of raising the temperature. In addition, steam exchanges heat with a low temperature fluid to become a condensate, and a condensed water return pipe (2
Return to the boiler section (10) through 3). At this time, the steam containing the non-condensable gas, the steam introduction pipe (21)
It comes into contact with the heat transfer tube bundle (30) more, but in the present invention, the pressure reducing boiler section (10) and the condensation chamber section (20) are separated, and a large-diameter steam introduction tube
(21) and a small-diameter condensed water return pipe (23) are connected to generate a circulating flow of steam, and the circulating flow of steam rinses away the non-condensable gas around the heat transfer tube bundle (30), Accumulate in the bend portion (U-shaped pipe portion) that is the end of the exchanger. However, in the present invention, since the noncondensable gas removal heat transfer tube (31) is arranged longer than the heat transfer tube bundle (30), the bend portion of the heat transfer tube (31) protruding from the heat transfer tube bundle (30) is disposed. Most of the non-condensable gas can be collected in the (U-shaped tube portion), and the non-condensable gas does not stay in the heat transfer tube bundle (30) portion that mainly performs heat exchange. Therefore, in the decompression boiler type carburetor according to the present invention, since the noncondensable gas does not stay in the heat transfer pipe (30) portion which mainly performs heat exchange, the heat transfer performance is not deteriorated. The temperature of the vaporized gas at the heat transfer tube outlet becomes stable. Less icing on the heat transfer tube surface.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing the structure of a decompression boiler type vaporizer according to the present invention. FIG. 2 is a circuit explanatory diagram showing a configuration of a conventional pressure reducing boiler. 1, 10 ...... decompression boiler section, 2 ...... water, 3, 11 ...... burner, 4, 12 ...... burner tube, 5 ...... heat transfer tube, 6 ...... LNG supply tube, 20 ...... condensation chamber section, 21 ...... Steam introduction pipe, 22 …… Non-condensable gas removal section, 23 …… Condensed water return pipe, 30 …… Heat transfer tube bundle, 31 …… Non-condensable gas removal heat transfer tube.

Front Page Continuation (72) Inventor Kanji Kaji 5-5-43- 211 Higashiterao, Tsurumi Ward, Yokohama City, Kanagawa Prefecture (72) Inventor, Yoji Sato 2-6, Nishinagasumotodori, Amagasaki City, Hyogo Sumitomo Precision Industries Ltd. In-house (72) Inventor Hitonobu 2-6 Nishi Nishisu Hon-dori, Amagasaki City, Hyogo Prefecture Sumitomo Precision Industry Co., Ltd. (72) Isya Sahara 2-6 Nishi-Nasu Hon-dori, Amagasaki City, Hyogo Prefecture Sumitomo Precision Industries, Ltd. (72) Inventor Seido Ikeda 2-6 Nishi-Nasusu Hondori, Amagasaki City, Hyogo Prefecture Sumitomo Precision Industries, Ltd.

Claims (1)

[Claims] 1. A burner pipe for transferring the combustion heat of a combustion burner is arranged in the lower part of a closed and decompressed can body, water is retained in the lower part of the can body including the same, and the upper space of the can body is steamed. Between the decompression boiler part that became a chamber and the condensation chamber part where the bundle of heat transfer tubes through which liquefied natural gas flows is introduced, and the lower part of the noncondensable gas removal part of the condensation chamber Condensed water return pipe that connects the bottom of the can body and the bottom of the can body is arranged, and a plurality of heat transfer tube bundles in the condensation chamber are projected longer than other heat transfer tubes to collect non-condensable gas. A decompression boiler type vaporizer characterized in that a gas removing unit is provided.