JPS62171596A - Vaporizing method for liquefied gas - Google Patents

Abstract

PURPOSE:To improve the vaporizing capacity of a liquefied gas, by increasing a temperature of liquefied or vaporized gas to be admitted into an air heat pipe vaporizer in the initial or final stage. CONSTITUTION:A liquefied gas such as a liquefied natural gas is admitted to one side of an indirect heat exchanger 1, and is then passed through a radiating portion 6 of an air heat pipe vaporizer 4 in the initial stage and the other side of the indirect heat exchanger 1. Then, the liquefied gas is passed through a radiating portion 10 of an air heat pipe vaporizer 8 in the final stage, which is provided independently of the air heat pipe exchanger 4 in the initial stage. With this arrangement, the vaporizing capacity of the liquefied gas is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to liquefied natural gas (LNG), liquefied petroleum gas,
The present invention relates to a method of vaporizing liquefied gas such as liquid nitrogen or liquid oxygen using an air-heated heat pipe and an indirect heat exchanger.

[Conventional technology]

The use of an air-heated heat pipe for vaporizing liquefied gas such as liquefied natural gas is described in Japanese Utility Model Application Publication No. 175798/1985 as a prior art.

As is well known, the heat pipe used here releases heat by evaporating the working fluid sealed inside the heat pipe at the heat receiving section at one end and condensing at the heat dissipating section at the other end. The heat is transferred from the heat receiving section to the heat dissipating section, and the heat transfer coefficient is significantly higher than that of indirect heat exchangers, so liquefied gas vaporization equipment using this heat pipe can efficiently liquefy the amount of heat held by the atmosphere. A type of liquefied gas vaporization equipment that vaporizes liquefied gas by simply ventilating the air outside a finned tube through which liquefied gas flows (for example, Showa 51-1427
This method has the advantage that the equipment can be made considerably smaller than the conventional method (described in Japanese Patent No. 13, etc.).

[Problem that the invention seeks to solve]

However, in the vaporization equipment using the heat pipe of the prior art, the heat dissipating part of the heat pipe is inserted into the vaporization tank, while the heat receiving part of the heat pipe is installed in the atmosphere and air is forced into it or natural ventilation is forced into it. The liquefied gas is vaporized in the vaporization tank, and the vaporization tank has a heat dissipation section inserted in the heat pipe.
By directly supplying extremely low-temperature liquefied natural gas of about -162°C, the temperature of the working fluid in the heat pipe becomes considerably low, below the freezing point. Heat pipes must be capable of repeating evaporation and condensation operations even at extremely low temperatures. In other words, heat pipes must use a special working fluid that can operate even at extremely low temperatures. Therefore, the heat pipe becomes expensive.
The equipment cost of the entire vaporizer using a large number of heat pipes is enormous, and the temperature of the working fluid in the heat pipes is considerably low, below the freezing point, as described above, resulting in heat loss. A large amount of moisture from the atmosphere freezes and adheres to the surface of the heat receiving part of the heat pipe, and the heat transfer coefficient of the heat pipe decreases in a short period of time. This meant that operations had to be stopped and removal work performed frequently.

The present invention aims to solve the above-mentioned problems when a heat pipe is used to vaporize liquefied gas such as liquefied natural gas.

[Means for solving problems]

Therefore, the first aspect of the present invention is to flow liquefied gas such as liquefied natural gas to one side of an indirect heat exchanger, and then pass it through the heat radiating part of the air-heated heat pipe type vaporizer in the previous stage. It passes through the other side of the heat exchanger, and then passes through the heat radiating part of the final stage air-heated heat pipe type vaporizer, which is prepared separately from the previous stage air-heated heat pipe type vaporizer. .

Moreover, the second aspect of the present invention is to flow liquefied gas such as liquefied natural gas in series through one example of a plurality of indirect heat exchangers, and then flow the same number of indirect heat exchangers into the preceding stages. The air temperature of the final stage is prepared separately from each of the previous stage air-heated heat pipe type vaporizers by passing alternately through the heat dissipation part of the air-heated heat pipe type vaporizer and the other side of the indirect heat exchanger. It is designed to pass through the heat radiation part of a heat pipe type vaporizer.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the first invention.
4 indicates a front-stage air-heated heat pipe type vaporizer, and the front-stage air-heated heat pipe type vaporizer 4 includes a plurality of heat pipes 5 and each heat pipe 5. and a vaporization tank 7 into which a heat radiating part 6 is inserted.

Further, in the figure, reference numeral 8 indicates a final stage air-heated heat pipe type vaporizer, and the final stage air-heated heat pipe type vaporizer 8
Like the pre-stage air-heated heat pipe type vaporizer 4, it is composed of a plurality of heat pipes 9 and a vaporization tank 11 into which a heat radiation part 10 of each heat vibrator 9 is inserted. In this case, one vaporization tank may be used for multiple heat pipes, and the heat radiating parts of the plurality of heat pipes may be inserted into this one vaporizing tank, but the heat radiating parts of each heat pipe may be , respectively, may be inserted into separate vaporization tanks, and the vaporization tanks may be configured to communicate with each other through pipes.

The heat receiving parts 12.13 with fins in the heat pipes 5.9 of the air-heated heat pipe type vaporizer 4.8 are both installed in the atmosphere, and the heat receiving parts 12.13 are connected to the air by a fan (not shown). is subjected to forced ventilation.

Then, liquefied gas such as liquefied natural gas is supplied into each heat exchanger tube 2 in the indirect heat exchanger 1 through the supply pipe 14, and the outlet pipe 15 from each heat exchanger tube 2 is connected to the previous stage. connected to a vaporization tank 7 in the air-temperature heat pipe type vaporizer 4, and an outlet pipe line 16 from the vaporization tank 7 is connected to the outer chamber 3 of each heat exchanger tube 2 in the indirect heat exchanger 1; , an outlet pipe line 17 from the outer chamber 3 of this indirect heat exchanger 1 is connected to the vaporization tank 11 of the final stage air-heated heat pipe type vaporizer 8, and a vaporized gas outlet pipe is connected to the vaporization tank 11. The configuration is such that the line 18 is connected.

In this configuration, the liquefied gas supplied from the supply pipe line 14 passes through one side of the indirect heat exchanger l, that is, the inside of the heat exchanger tube 2, and then is vaporized from the outlet pipe line 15 in the air-heated heat pipe type vaporizer 4. It flows into the tank 7, is heated and vaporized by contacting the heat radiation part 6 of the heat pipe 5 in the vaporization tank 7, and then flows from the vaporization tank 7 through the outlet pipe 16 to the indirect heat exchanger. After passing through the other side of 1, that is, the inside of the heat exchanger tube outer chamber 3, it flows out from the outlet pipe 17.

That is, when the liquefied gas flowing into the vaporization tank 7 in the pre-stage air-heated heat pipe type vaporizer 4 from the outlet pipe line 15 flows through one side of the indirect heat exchanger 1, that is, inside the heat transfer tube 2, , it is heated by exchanging heat with the vaporized gas flowing in the other side of the indirect heat exchanger l, that is, the outer chamber 3, and after the temperature rises, it is transferred to the vaporization tank 7.
It will flow inside. Therefore, the inside of the vaporization tank 7 in the pre-stage air-heated heat pipe type vaporizer 4 can be maintained at a higher temperature than when liquefied gas is directly supplied into the vaporization tank 7 as in the prior art. .

On the other hand, the temperature of the vaporized gas flowing through the other side, the outer chamber 3, of the indirect heat exchanger 1 decreases due to heat exchange with the extremely low temperature liquefied gas flowing within the heat transfer tubes 2. The vaporized gas whose temperature has been lowered flows from the outlet pipe 17 into the vaporization tank 11 of the final stage air-heated heat pipe type vaporizer 8, contacts the heat dissipation part 10 of the heat pipe 9 in the vaporization tank 11, and Since it is heated, completely vaporized vaporized gas can be taken out from the vaporized gas outlet pipe 18 at a temperature close to that of the atmosphere.

Furthermore, the vaporized gas flowing into the vaporization tank 11 in the final stage air-heated heat pipe type vaporizer 8 is heated in the preceding stage air-heated heat pipe type vaporizer 4 and is therefore supplied from the supply pipe line 14. Since the temperature is higher than the temperature of the liquefied gas, the temperature inside the vaporization tank 11 must be maintained at a higher temperature than when the liquefied gas is directly supplied to the vaporization tank 11 as in the prior art. This is possible.

In this way, the temperature inside the vaporization tank 7 in the air-heated heat pipe type vaporizer 4 in the previous stage and the temperature in the vaporization tank 11 in the air-heated heat pipe type vaporizer 8 in the final stage are controlled in the same way as in the prior art. Since the temperature can be higher than that in the case where liquefied gas is directly supplied to The amount of ice that freezes on the surface of the heat receiving part 13 in the heat pipe 9 of No. 8 is reduced by the increase in temperature as described above, and the amount of ice that freezes on the surface of the heat receiving part 13 in the heat pipe 5. This eliminates the need for special working fluids that operate at very low temperatures, and allows the use of working fluids that operate at higher temperatures.

2 and 3 show an embodiment of the second invention,
In this embodiment, the indirect heat exchanger 1 in the embodiment shown in FIG. The air-heated heat pipe type vaporizer 2 at the front stage in the embodiment shown in FIG.
There are a plurality of air-heated heat pipe type vaporizers 4a at the first front stage and air-heated heat pipe type vaporizers 4b at the second front stage.

That is, the liquefied gas supplied from the supply pipe line 14 is transferred to one side (heat exchanger tube 2a) of each indirect heat exchanger 1a, lb.
.
The heat dissipation part 6a of the heat pipe 5a is connected to the inserted vaporization tank 7a, and the outlet pipe line 16a from the vaporization tank 7a is connected to the outer chamber 3b (other side) of the heat transfer tube in the second indirect heat exchanger 1b. The outlet pipe line 17b from the outer chamber 3b is connected to the second pre-stage air-heated heat pipe type vaporizer 4.
At b, the heat radiation part 6b of the heat pipe 5b is connected to the inserted vaporization tank 7b, and the outlet pipe line 16b from the vaporization tank 7b is connected to the outer chamber 3a (other side) of the heat transfer tube in the first indirect heat exchanger 1a. and this outer chamber 3
Connect the outlet pipe 17a from a to the vaporization tank 11 in the final stage air-heated heat pipe type vaporizer 8, or
As shown in FIG. 3, the outlet pipe line 16a from the vaporization tank 7a in the first pre-stage empty salt beat pipe type vaporizer 4a is connected to the outer chamber 3a of the heat transfer tube in the first indirect heat exchanger 1a.
(on the other side), and the outlet pipe 17 from the outer chamber 3a
a to the vaporization tank 7b in the second front-stage air-temperature heat vibrator vaporizer 4b, and connect the outlet pipe line 16b from the vaporization tank 7b to the outer chamber 3b (on the other side) of the heat transfer tube in the second indirect heat exchanger 1b. ), and by connecting the outlet pipe 17b from this outer chamber 3b to the vaporization tank 11 in the final stage air-heated heat pipe type vaporizer 8, from one side of the second indirect heat exchanger 1b. The leaked liquefied gas is transferred to the vaporization tank 7a in the first pre-stage air-heated heat pipe type vaporizer 4a, the vaporization tank 7b in the second pre-stage air-heated heat pipe type vaporizer 4b, and the heat exchanger tube in the first indirect heat exchanger 1a. and the outer chamber 3b (other side) of the heat transfer tube in the second indirect heat exchanger 1b.
After passing through the vaporizer tank 11 in the final stage air-heated heat pipe type vaporizer 8,

With this configuration, the liquefied gas supplied from the supply pipe line 14 is heated in both the first indirect heat exchanger 1a and the second indirect heat exchanger 1b, and then transferred to the first pre-stage air heating heat pipe. Since the liquefied gas enters the vaporizer 4a, the temperature of the liquefied gas introduced into the first stage air-heated heat pipe vaporizer can be made higher than in the case shown in FIG. Also, regarding the second front stage and final stage air-heated heat pipe type vaporizer, the amount of heat exchanged per indirect heat exchanger, that is, the degree of cooling of the vaporized gas once heated to near atmospheric temperature, is compared to the case shown in Figure 1. Since the amount of heat is reduced, the temperature of the liquefied gas introduced into each air-heated heat pipe type vaporizer can be made higher.

In FIG. 2, both front-stage air-temperature heat pipe type vaporizers 4a are used to vaporize liquefied natural gas at -162°C when the atmospheric temperature is 20°C.

4b inlet and outlet temperatures and both indirect heat exchangers la, l
Examples of the temperatures at the inlet and outlet of b are as follows.

Inlet temperature of heat exchanger tubes 2a in first indirect heat exchanger 1a -162°C Outlet temperature of heat exchanger tubes 2a in first indirect heat exchanger 1a -129°C Inlet temperature of heat exchanger tubes 2b in second indirect heat exchanger 1b -129 °C Outlet temperature of the heat transfer tube 2b in the second indirect heat exchanger 1b -88 °C Inlet temperature of the first pre-stage air-heated heat pipe type vaporizer 4a -88 °C Outlet temperature of the first pre-stage air-heated heat pipe type vaporizer 4a 10 ℃ Inlet temperature of heat exchanger tube outer chamber 3b in second indirect heat exchanger 1b 10'C Outlet temperature of heat exchanger tube outer chamber 3b in second indirect heat exchanger 1b -89℃ Second pre-stage air temperature heat pipe type vaporizer 4b -89°C Outlet temperature of the second pre-stage air-heated heat pipe type vaporizer 4b 10°C Inlet temperature of the heat transfer tube outer chamber 3a in the first indirect heat exchanger 1a 10'C Outlet temperature of heat tube outer chamber 3a -87°C Inlet temperature of final stage air-heated heat pipe type vaporizer 8 -87°C Outlet temperature of final stage air-heated heat pipe type vaporizer 8 As is clear from the table 10" Although the vaporized gas can be taken out from the final stage air-heated heat pipe type vaporizer 8 at a temperature close to atmospheric temperature, the first pre-stage air-heated heat pipe type vaporizer 4a and the second pre-stage air-heated heat Pipe vaporizer 4
The temperature of the liquefied gas or vaporized gas entering each of the air-heat pipe type vaporizer 8 and the air-heated heat pipe type vaporizer 8 can be made higher than in the conventional case described above.

Note that the indirect heat exchanger and the pre-stage air-heated heat pipe type vaporizer are not limited to two stages as shown in Figures 2 and 3, but may be configured in multiple stages of three or more stages. Furthermore, it goes without saying that the atmospheric ventilation to each air-temperature heat pipe type vaporizer is not limited to the forced ventilation of the embodiment, but may be natural ventilation.

〔Effect of the invention〕

As described above, the first aspect of the present invention is to flow liquefied gas such as liquefied natural gas to one side of an indirect heat exchanger, and then pass it through the heat radiating part of the air-heated heat pipe type vaporizer in the preceding stage. By passing through the other side of the heat exchanger, and then passing through the heat dissipation section of the final stage air-heated heat pipe type vaporizer, which is prepared separately from the previous stage air-heated heat pipe type vaporizer, the final Although the stage air-heated heat pipe type vaporizer can extract completely vaporized gas at a temperature close to atmospheric temperature, the liquefied gas heated in the front stage air-heated beat pipe type vaporizer is used as the heat source. By using the indirect heat exchanger, the temperature of the liquefied gas or vaporized gas entering the first-stage air-heated heat pipe type vaporizer and the final-stage air-heated heat pipe type vaporizer can be made higher than in the case of the prior art. Therefore, the freezing phenomenon in the double air-heated heat pipe type vaporizer is reduced, the interval between operations for removing frozen substances can be increased, and the vaporization ability of liquefied gas can be improved.

Moreover, there is no need to use a special working fluid that operates at extremely low temperatures as in the prior art as the working fluid in the heat pipe of the double-air temperature heat pipe type vaporizer (this makes the heat pipe inexpensive. This has the effect of reducing overall equipment costs.

Moreover, the second aspect of the present invention is to flow liquefied gas such as liquefied natural gas in series through one example of a plurality of indirect heat exchangers, and then flow the same number of indirect heat exchangers into the preceding stages. The air temperature of the final stage is prepared separately from each of the previous stage air-heated heat pipe type vaporizers by passing alternately through the heat dissipation part of the air-heated heat pipe type vaporizer and the other side of the indirect heat exchanger. By passing the heat through the heat dissipation part of the heat pipe type vaporizer, completely vaporized gas can be taken out at a temperature close to the atmospheric temperature than the final stage air-heated heat pipe type vaporizer. ,
The temperature of the liquefied gas or vaporized gas entering each air-heated heat pipe type vaporizer can be made higher than in the case of the first invention (because it is possible to further promote the effect of the first invention, and lower the temperature). It has an effect that is effective in vaporizing liquefied gas at a certain temperature.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a diagram of the first embodiment, FIG. 2 is a diagram of the second embodiment, and FIG. 3 is a diagram of the third embodiment. 1, la, Lb... - indirect heat exchanger, 2.2a. 2b...Heat transfer tube, 3.3a, 3b...Outer chamber of heat transfer tube, 4.4a, 4b...Previous air temperature heat pipe type vaporizer, 5.5a, 5b... Heat pipe, 6゜6a, 6b... Heat dissipation section, 7.7a, 7b... Vaporization tank, 8... Final stage air temperature heat pipe type vaporizer, 9... Heat pipe , 10... heat dissipation section, 1
1... Vaporization tank, 14... Liquefied gas supply pipe line, 15.16.16a, 16b, 17.17a, 17
b... Outlet pipe line, 18... Vaporized gas outlet pipe line.

Claims (2)

[Claims] (1) After flowing liquefied gas such as liquefied natural gas to one side of the indirect heat exchanger, it passes through the heat dissipation part of the air-heated heat pipe type vaporizer in the previous stage to the other side of the indirect heat exchanger. A method for vaporizing liquefied gas, characterized in that the liquefied gas is passed through a heat dissipation section in a final stage air-heated heat pipe type vaporizer prepared separately from the preceding stage air-heated heat pipe type vaporizer. (2) After flowing liquefied gas such as liquefied natural gas in a series on one side of a plurality of indirect heat exchangers, air-heated heat pipe vaporization is carried out in the same number of preceding stages as the indirect heat exchangers. In the final stage air-heated heat pipe type vaporizer, which is prepared separately from each of the previous stage air-heated heat pipe type vaporizers, A method for vaporizing liquefied gas, characterized by passing the liquefied gas through a heat radiation section.