KR101908565B1 - Boil-Off Gas Reliquefaction Method and System for LNG Vessel - Google Patents

Abstract

An evaporative gas re-liquefaction system for LNG is disclosed.
The LNG line evaporation gas re-liquefaction system comprises a heat exchanger for heat-exchanging a high-temperature fluid, which is an evaporation gas compressed by a compressor, with a low-temperature fluid as an evaporation gas before compression, And an expansion means for expanding the fluid cooled by the heat exchanger, wherein the heat exchanger comprises: a core including a plurality of blocks in which heat exchange occurs between the high temperature fluid and the low temperature fluid; And a fluid dispersing means for dispersing a fluid flowing into the core or a fluid discharged from the core, wherein the core includes a plurality of blocks, and the fluid dispersing means is provided with a heat exchanger do.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an LNG carrier,

The present invention relates to a method and system for re-liquefying a surplus evaporation gas remaining in an engine from an evaporation gas generated in a storage tank of an LNG carrier by using evaporation gas itself as a refrigerant.

In recent years, consumption of liquefied gas such as Liquefied Natural Gas (LNG) has been rapidly increasing worldwide. The liquefied gas obtained by liquefying the gas at a low temperature has an advantage of being able to increase the storage and transport efficiency because the volume becomes very small as compared with the gas. In addition, liquefied natural gas, including liquefied natural gas, can be removed as an eco-friendly fuel with less air pollutant emissions during combustion because air pollutants can be removed or reduced during the liquefaction process.

Liquefied natural gas is a colorless transparent liquid which can be obtained by cooling methane-based natural gas to about -163 ° C and liquefying it, and has a volume of about 1/600 as compared with natural gas. Therefore, when the natural gas is liquefied and transported, it can be transported very efficiently.

However, since the liquefaction temperature of natural gas is a cryogenic temperature of -163 ° C at normal pressure, liquefied natural gas is susceptible to temperature change and is easily evaporated. As a result, the storage tank storing the liquefied natural gas is subjected to heat insulation, but the external heat is continuously transferred to the storage tank. Therefore, in the transportation of liquefied natural gas, the liquefied natural gas is naturally vaporized continuously in the storage tank, -Off Gas, BOG) occurs.

Evaporation gas is a kind of loss and is an important issue in transport efficiency. Further, when the evaporation gas accumulates in the storage tank, the internal pressure of the tank may rise excessively, and there is a risk that the tank may be damaged. Accordingly, various methods for treating the evaporative gas generated in the storage tank have been studied. Recently, a method of re-liquefying the evaporated gas and returning it to the storage tank for treating the evaporated gas, a method of returning the evaporated gas to the storage tank And a method of using it as an energy source of a consuming place.

As a method for re-liquefying the evaporation gas, there is a method of re-liquefying the evaporation gas by heat exchange with the refrigerant by providing a refrigeration cycle using a separate refrigerant, and a method of re-liquefying the evaporation gas by using the evaporation gas itself as a refrigerant . Particularly, the system adopting the latter method is called a Partial Re-liquefaction System (PRS).

On the other hand, there are gas-fuel engines such as DFDE, X-DF engine and ME-GI engine which can be used natural gas among the engines used in ships.

The DFDE adopts the Otto Cycle, which consists of four strokes, and injects natural gas with a relatively low pressure of about 6.5 bar into the combustion air inlet, compressing the piston as it rises.

The X-DF engine is composed of two strokes, using natural gas of about 16 bar as fuel and adopting autocycle.

The ME-GI engine consists of two strokes and employs a diesel cycle in which high pressure natural gas at around 300 bar is injected directly into the combustion chamber at the top of the piston.

An object of the present invention is to provide a method and system for liquefying LNG vaporized gas that can stabilize the liquefaction performance and increase the overall liquefaction efficiency and liquefaction amount.

According to an aspect of the present invention,

A heat exchanger for exchanging heat between the high temperature fluid as the evaporation gas compressed by the compressor and the low temperature fluid as the evaporation gas before compression; And an expansion means for expanding the fluid cooled by the heat exchanger, wherein the heat exchanger comprises: a core including a plurality of blocks in which heat exchange occurs between the high temperature fluid and the low temperature fluid; And a fluid dispersing means for dispersing a fluid flowing into the core or a fluid discharged from the core, wherein the core includes a plurality of blocks, and the fluid dispersing means is provided with a heat exchanger An evaporation gas re-liquefaction system of LNG is provided.

The fluid dispersion means may impart a resistance to the fluid to disperse the fluid.

The fluid dispersing means may be a perforated plate.

The heat exchanger may include a support member separated from the heat exchanger by a predetermined distance and coupled to the heat exchanger, and the fluid dispersion means may be sandwiched between the spaced apart support members.

The heat exchanger may include at least one header for sending the fluid flowing into the heat exchanger to the core or discharging the fluid discharged from the core to the outside of the heat exchanger, .

The heat exchanger may include a support member spaced apart from the core by a predetermined distance and coupled to the heat exchanger, and the fluid dispersion means may be sandwiched between the core and the support member.

The fluid dispersing means may have a shape in which both ends extend parallel to and apart from the core in a direction away from the core.

The heat exchanger may include at least one header for sending the fluid flowing into the heat exchanger to the core or discharging the fluid discharged from the core to the outside of the heat exchanger, .

According to another aspect of the present invention, there is provided a heat exchanger comprising: a heat exchanger for heat-exchanging a high-temperature fluid, which is an evaporation gas compressed by a compressor, with a low-temperature fluid, And an expansion means for expanding the fluid cooled by the heat exchanger, wherein the heat exchanger comprises: a core including a plurality of blocks in which heat exchange occurs between the high temperature fluid and the low temperature fluid; Fluid distributing means for dispersing a fluid flowing into the core or a fluid discharged from the core; And at least one header for sending the fluid introduced into the heat exchanger to the core or discharging the fluid discharged from the core to the outside of the heat exchanger, A combined LNG vaporized gas remelting system is provided.

According to the present invention, even if the flow rate of the evaporative gas to be re-liquefied fluctuates, the liquefaction performance can be stably maintained.

According to an embodiment of the present invention, the fluid supplied to the heat exchanger or the fluid discharged from the heat exchanger can be dispersed to relieve the concentration of the refrigerant in any one of the blocks.

According to an embodiment of the present invention, the refrigerant can be evenly dispersed not only between a plurality of blocks but also within one block, and can maintain the spacing between the perforated plate and the core. Particularly, it is possible to prevent the flow of the fluid to the core by preventing the perforated plate and the core from contacting each other by blocking the flow path.

According to an embodiment of the present invention, since the perforated plate is coupled with the heat exchanger so that heat expansion and contraction can be eliminated, even if the perforated plate is contracted due to contact with the evaporating gas at a cryogenic temperature, the perforated plate is not bent or broken, It is not damaged.

According to an embodiment of the present invention, since the heat exchanger includes a channel having a shape capable of providing resistance to the fluid, it is possible to mitigate or prevent the phenomenon that the refrigerant concentrates on one of the blocks without adding a separate member for dispersing the fluid can do.

1 shows a basic model for explaining the concept of evaporation gas remelting according to an embodiment of the present invention.
Fig. 2 shows a process calculation program of the re-liquefaction performance evaluation experiment according to the evaporative gas pressure of the object of re-liquefaction according to the present invention.
FIG. 3 is a graph showing the relationship between the pressures of the high-temperature fluid and the low-temperature fluid in the case where the pressure of the evaporative gas to be liquefied is 39 bara or 50 bara to 120 bara increased by 10 bara in the evaporation gas remelting system according to the embodiment of the present invention. FIG. 3 is a graph showing a temperature change according to a heat flow rate. FIG.
FIG. 4 is a graph showing the relationship between the heat flux of each of the high-temperature fluid and the low-temperature fluid in the case of 130 bara to 200 bara and 300 bara, in which the pressure of the evaporative gas to be liquefied is increased by 10 bara in the evaporation gas remelting system according to the embodiment of the present invention. FIG.
FIG. 5 is a schematic diagram of an evaporative gas re-liquefaction system according to an embodiment of the present invention when the evaporative gas pressure to be resuplicated is 39 bara.
FIG. 6 is a schematic diagram of an evaporative gas re-liquefaction system according to an embodiment of the present invention when the evaporative gas pressure to be re-liquefied is 150 bara.
FIG. 7 is a schematic diagram of an evaporative gas remelting system in accordance with an embodiment of the present invention when the evaporative gas pressure to be re-liquefied is 300 bara.
Figures 8 and 9 are graphs showing the "liquefied amount" of Table 1 at a pressure range of 39 bara to 300 bara.
10 is a schematic view of a conventional PCHE.
11 is a schematic view of a heat exchanger according to a first preferred embodiment of the present invention.
12 is a schematic view of a first bank or a second bank included in a heat exchanger according to a second preferred embodiment of the present invention.
13 is a schematic view of a first partition and a first perforated plate included in a heat exchanger according to a second preferred embodiment of the present invention.
14 is a schematic view of a second partition and a second perforated plate included in a heat exchanger according to a second preferred embodiment of the present invention.
15 is a schematic view of a third partition or a fourth partition included in the heat exchanger according to the second preferred embodiment of the present invention.
16 is a schematic view of a third partition and a third perforated plate included in a heat exchanger according to a second preferred embodiment of the present invention.
17 is a schematic view of a fourth partition and a fourth perforated plate included in a heat exchanger according to a second preferred embodiment of the present invention.
FIG. 18A is a schematic view showing a refrigerant flow in a conventional heat exchanger, FIG. 18B is a schematic view showing a refrigerant flow in the heat exchanger according to the first preferred embodiment of the present invention, FIG. FIG. 3 is a schematic view showing a refrigerant flow of a heat exchanger according to a second preferred embodiment of the present invention. FIG.
Fig. 19 (a) is a schematic view showing the position of a temperature sensor installed for measuring the internal temperature of the heat exchanger, Fig. 19 (b) is a graph showing the temperature inside the heat exchanger measured by the temperature sensor FIG.
20 is a schematic view showing a part of a heat exchanger according to a third preferred embodiment of the present invention.
21 is an enlarged schematic view of part A of Fig.
22 is a schematic view showing a part of a heat exchanger according to a fourth preferred embodiment of the present invention.
23 is an enlarged schematic view of a portion B in Fig.
24 (a) is a schematic view of the overall shape of the heat exchanger, (b) is a schematic view of the block, and (c) is a schematic view of the channel plate.
25 (a) is a schematic view of the channel plate for low-temperature fluid shown in FIG. 24 (c) viewed in the direction C, FIG. 25 (b) is a schematic view of a channel of the channel plate for low-temperature fluid in a conventional heat exchanger (c) is a schematic view of a channel of a channel plate for a low temperature fluid of a heat exchanger according to a fifth preferred embodiment of the present invention, Lt; / RTI > is a schematic view of the channel of the plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. INDUSTRIAL APPLICABILITY The present invention can be applied to various applications such as a ship equipped with an engine using natural gas as fuel and a ship including a liquefied gas storage tank. In addition, the following examples can be modified in various forms, and the scope of the present invention is not limited to the following examples.

Systems for the treatment of the evaporative gas to be described below of the present invention include all types of vessels and marine structures equipped with storage tanks capable of storing cold liquid or liquefied gas, such as LNG Carrier, Liquefied Ethane Gas Carrier) and LNG RV, as well as LNG FPSO, LNG FSRU and other marine structures. For the sake of convenience, the LNG carrier is an LNG carrier, an LNG carrier, a LNG carrier, a LNG carrier, a LNG carrier, and a LNG FSRU.

The fluid in each line of the present invention may be in any one of a liquid state, a gas-liquid mixed state, a gas state, and a supercritical fluid state, depending on operating conditions of the system.

1 shows a basic model for explaining the concept of evaporation gas remelting according to an embodiment of the present invention.

Referring to FIG. 1, in the present invention, evaporation gas (1) discharged from a storage tank is sent to a heat exchanger as a refrigerant, compressed by a compressor, evaporated gas compressed by a compressor is used as fuel for an engine ), Surplus evaporation gas (3) remaining after satisfying the required amount of the engine is sent to the heat exchanger, and the evaporation gas (1) discharged from the storage tank is cooled by heat exchange with the refrigerant.

The evaporative gas to be re-liquefied after being compressed by the compressor and cooled by the heat exchanger is separated into a liquid component and a gas component by a gas-liquid separator after passing through a decompression means (for example, an expansion valve and an expander). The liquid component separated by the gas-liquid separator is returned to the storage tank, and the gas component separated by the gas-liquid separator is combined with the evaporated gas (1) discharged from the storage tank and supplied to the heat exchanger again as a refrigerant.

The present invention is characterized not by using a separate additional cycle for re-liquefying the evaporation gas but by re-liquefying the evaporation gas using the evaporation gas discharged from the storage tank itself as a refrigerant. Of course, in some cases, a separate refrigeration cycle may be provided to ensure re-liquefaction of all evaporative gases. The separate cycle may require additional equipment or require additional power, but it can be ensured that almost all of the evaporation gas is re-liquefied.

In the system for re-liquefying the evaporation gas using the evaporation gas itself as the refrigerant as in the present invention, the re-liquefaction performance depends on the pressure of the re-liquefied evaporation gas (hereinafter referred to as " reflux target evaporation gas & The results are as follows. Experiment 1 (hereinafter referred to as "Experiment 1") is performed to find the re-liquefaction performance according to the pressure of the evaporation gas to be re-liquefied.

< Experiment 1  >

The conditions of the re-liquefaction performance evaluation test according to the pressure of the evaporation gas to be resuspended are as follows.

1. Target vessel: LNG carrier including high-pressure gas injection engine as a propulsion engine and low-pressure engine as a power generation engine

2. Process calculation program: Aspen HYSYS V8.0 (shown in FIG. 2)

3. Property calculation formula: Peng-Robinson equation

4. Amount of Evaporation Gas: Since the evaporation gas of about 3500 kg / h to 4000 kg / h is generated for a 170,000 CBM (cubic meter) LNG carrier, 3800 kg / h is applied in this experiment.

5. Components of evaporative gas: 10% of nitrogen (N ₂ ) and 90% of methane (CH ₄ ) are commonly applied to the evaporated gas discharged from the storage tank and the evaporated gas compressed by the compressor.

6. Temperature and pressure of evaporation gas discharged from storage tank: Pressure is 1.06bara and temperature is -120 degC.

7. Fuel Consumption in the Engine: In the actual operation of the ship, the engine is operated at a low load considering the economical efficiency. In this experiment, the total amount of the evaporation gas used in the propulsion engine and the power generation engine, Assuming 70% of the gas (3800 kg / h), which is 2,660 kg / h.

8. Compressor capacity: Normally, the compressor capacity does not exceed 150% of the evaporation gas generated from the storage tank. In this calculation, 120% of the evaporation gas generated from the storage tank (3800 kg / h × 120% = 4650kg / h) is applied.

9. Performance of Heat Exchanger: Logarithmic Mean Temperature Difference (LMTD) of 13 degC or more and Minimum Approach of 3 degC or more are applied.

In designing the heat exchanger, the temperature and the heat flow rate of the low-temperature fluid and the high-temperature fluid flowing into the heat exchanger are fixed, respectively, so that the temperature of the fluid used as the refrigerant does not become higher than the temperature of the fluid to be cooled In the graph, the Logarithmic Mean Temperature Difference (LMTD) is minimized while avoiding intersection of the graph of the low temperature fluid and the graph of the high temperature fluid.

The logarithmic mean temperature difference (LMTD) is the temperature difference between the low-temperature fluid and the low-temperature fluid in the opposite direction and the opposite direction. In the case of countercurrent flow, the low-temperature fluid passes through the heat exchanger And the temperature after the high-temperature fluid has passed through the heat exchanger is th2 and d1 = th2-tc1, d2 = th1-tc2, d1) / ln (d2 / d1). As the logarithmic mean temperature difference is smaller, the efficiency of the heat exchanger increases.

The logarithmic mean temperature difference (LMTD) is expressed as the interval between the low-temperature fluid used as the coolant and the high-temperature fluid cooled by the heat exchange with the coolant. As the gap between the cool fluid and the high- Means that the temperature difference (LMTD) is small, and that the logarithmic mean temperature difference (LMTD) is small means that the efficiency of the heat exchanger is high.

The thermodynamic calculations under the experimental conditions 1 to 9 were carried out in order to quantitatively demonstrate the effect of the high pressure compression of the evaporative gas to the liquefaction on the liquefaction performance. In order to verify the re-liquefaction performance and the cooling curve characteristics of the heat exchanger according to the pressure of the evaporation gas, the evaporation gas pressure to be re-liquefied is set at 39bara, 10bara, 50bara to 200bara, 250bara and 300bara, The liquefaction amount and the cooling curve of the heat exchanger were thermodynamically calculated.

FIG. 3 is a graph showing the relationship between the pressures of the high-temperature fluid and the low-temperature fluid in the case where the pressure of the evaporative gas to be liquefied is 39 bara or 50 bara to 120 bara increased by 10 bara in the evaporation gas remelting system according to the embodiment of the present invention. FIG. 4 is a graph showing the temperature change depending on the amount of heat flow. FIG. 4 is a graph showing the change of the temperature of the evaporative gas remover system according to an embodiment of the present invention when the pressure of the evaporative gas to be religmated is increased from 10 bara to 130 bara and 300 bara Temperature fluid according to the heat flow rate of each of the high-temperature fluid and the low-temperature fluid.

5 is a schematic view of the evaporation gas re-liquefaction system according to an embodiment of the present invention when the evaporation gas pressure to be re-liquefied is 39 bara, and Fig. 6 is a schematic view FIG. 7 is a schematic view of an evaporative gas re-liquefaction system according to an embodiment of the present invention when the evaporative gas pressure to be refluxed is 300 bara. FIG.

Table 1 below shows calculation values of the liquefaction performance according to the pressure of the evaporative gas to be re-liquefied in the evaporation gas re-liquefaction system according to the embodiment of the present invention.

The pressure of the evaporative gas to be re-liquefied
(bara) Cooling temperature before expansion
(degC) Amount of resolidification
(kg / h) Relative liquefaction amount relative ratio
(%) 39 -97.7 563.8 100.0 50 -96.1 712.8 126.4 60 -99.6 821.6 145.7 70 -103.8 909.3 161.3 80 -107.8 979.9 173.8 90 -111.5 1036.4 183.9 100 -114.6 1080.5 191.7 110 -117.0 1113.8 197.6 120 -119.0 1137.9 201.9 130 -120.4 1154.7 204.8 140 -121.4 1165.9 206.8 150 -122.1 1173.8 208.1 160 -122.4 1174.6 208.4 170 -122.4 1172.7 208.0 180 -122.4 1170.7 207.7 190 -122.4 1168.6 207.3 200 -122.4 1166.3 206.9 250 -122.5 1153.4 204.6 300 -122.6 1138.2 201.9

8 and 9 are graphs showing the "liquefied amount" of Table 1 in a pressure range of 39 bara to 300 bara.

3 to 9 and Table 1, the result is that in the cooling curve of the evaporative gas to be religinated, even if the compression pressure of the evaporative gas is supercritical state, the latent heat period is shown as 39 bara in the range of 50 bara to 100 bara (The cooling temperature before expansion is -122.4 DEG C, the liquefaction amount is 1174.6 kg / h, and the relative liquefaction amount ratio is 208.4%) at a compression pressure of 160 bara, Respectively.

The greatest difference between the case of low-pressure and the case of high-pressure evaporation gas to be resupplyed is the pre-expansion cooling temperature. As can be seen from FIG. 9, due to the difference in the cooling curve depending on the pressure, in the case of the low pressure, the cooling temperature before the expansion is limited, so that the cooling temperature can not be lowered much. On the other hand, It is possible to cool to near.

This difference is due to the nature of the methane (CH ₄ ), which is the main component of the evaporative gas, and there exists a latent heat section below the critical pressure (about 47 bara for pure methane), and above the critical pressure there exists a section similar to the latent heat section However, it can be seen that it has decreased. Therefore, from the viewpoint of the amount of resuspension, it is preferable that the evaporation gas is re-liquefied at a critical pressure of 47 bar or more.

Meanwhile, the ME-GI engine sets the supply pressure of the fuel gas in the range of 150 bara to 400 bara (mainly operating at 300 bara). As shown in Fig. 8 and Table 1, the pressure of the evaporative gas to be reflocculated is 150 to 170 bara And the re-liquefaction amount is the maximum value. When the ME-GI engine is refueled while supplying fuel to the ME-GI engine, the control relating to the re-liquefaction or the fuel supply .

The 'liquefied amount' in Table 1 indicates the amount of the liquefied liquefied gas separated by the gas-liquid separator 40 after passing through the compressor 10, the heat exchanger 20 and the decompression device 30 in Figs. Represents the flow rate of the natural gas, and the "relative liquefaction amount ratio" represents the relative ratio of the liquefaction amount at each pressure to the liquefaction amount in the case where the liquefaction target gas is 39 bara in%.

On the other hand, 're-liquefaction ratio' may indicate re-liquefaction performance. The re-liquefaction ratio represents a value obtained by dividing the flow rate of the re-liquefied liquefied natural gas by the flow rate of the entire evaporative gas to be re-liquefied. That is, the 'liquefaction amount' represents the absolute amount of the liquefied natural gas that has been re-liquefied, and the 'liquefaction rate' represents the ratio of the liquefied natural gas that has been re-liquefied in the total liquefaction target evaporation gas.

For example, if the speed of the ship is low and the amount of evaporative gas used in the propulsion engine is reduced, the amount of evaporative gas to be reflocculated increases and the amount of 'refloatable' may also increase. However, under the condition of Experiment 1, since the sum of the evaporative gas discharged from the storage tank and the gas component separated by the gas-liquid separator, which is a fluid used as a refrigerant, is almost constant because of the capacity limitation of the compressor, .

In Experiment 1, the flow rate of the refrigerant flowing into the compressor is 4560 kg / h, which is 120% of the evaporation gas generated from the storage tank at 3800 kg / h. Of these, the engine consumption is 2660 kg / h (ME- h + DFDG 618 kg / h) is 1900 kg / h.

When the pressure of the evaporative gas to be reflocculated was increased up to 400 bara, the difference was not much different from that of 300 bara, and the difference of the liquefaction flow rate at 150 bara and 400 bara was within 4%.

On the other hand, in the graphs shown in FIG. 3 and FIG. 4, the high temperature fluid indicated by red (upper) means the evaporative gas to be relubarized, and the low temperature fluid indicated by blue (lower) means the evaporated gas discharged from the storage tank, do.

In the graphs of FIG. 3 and FIG. 4, the linear section without temperature change is the latent heat section even with the change in the heat flow rate, and the characteristic of the methane in which the latent heat section is not present in the supercritical fluid state There is a difference. That is, in the case where the evaporative gas to be re-liquefied is a supercritical fluid, the liquefaction flow rate and the re-liquefaction ratio are high because there is no latent heat section during heat exchange.

Taken together, the remelting performance is high in the case of the supercritical state of the evaporative gas to be re-liquefied, particularly in the range of 100 bara to 400 bara, preferably in the range of 150 bara to 400 bara, It can be seen that the remelting performance is high at 150 bara to 300 bara.

Considering that the required pressure of the ME-GI engine is 150 bara to 400 bara, the compressed evaporation gas is used as it is to be refluxed to meet the required pressure of the ME-GI engine, It can be seen that there is a very advantageous advantage in linking the system for supplying fuel to the ME-GI engine and the evaporation gas re-liquefaction system using the evaporation gas itself as a refrigerant.

Meanwhile, in Experiment 1 described above, the re-liquefaction performance according to the evaporation gas pressure to be re-liquefied was evaluated by a simulation program. Then, in order to examine whether these results are the same in actual re-liquefaction apparatus using a heat exchanger (Hereinafter referred to as "Experiment 2") using a PCHE (Printed Circuit Heat Exchanger).

< Experiment 2  >

Under actual operating conditions, the amount of evaporative gas generated is constant, but the amount of evaporative gas used in the engine changes. Therefore, in Experiment 2, the re-liquefaction performance in an actual remelting device was evaluated while changing the flow rate of the re-liquefying gas. For the sake of convenience of experiments, nitrogen is generally used instead of explosive methane, and the temperature of nitrogen used as a refrigerant is controlled to be the same as that of the evaporated gas discharged from the storage tank. The conditions were the same as the conditions 1 to 9 of FIG.

In addition, because the fuel consumption of the ME-GI engine varies depending on the operating conditions, actual LNG carriers are assumed and tested. Under the condition of Experiment 1, assuming that the size of the ME-GI engine of the LNG carrier is 25 MW (2 units of 12.5 MW) and operating at full speed, it will be about 19.5 knots (fuel consumption of the engine is about 3800 kg / h) If operated at an economical speed, it will operate at about 17 knots (fuel consumption of the engine is about 2660 kg / h). Therefore, considering the actual operating conditions, most operating conditions will be the highest operating speed of 19.5 knots, the economical operating speed of 17 knots, and the berth (ME-GI engine fuel consumption of 0 and DFDG fuel consumption of 618 kg / h) . In Experiment 2, re-liquefaction performance was tested under these conditions.

In the case of using nitrogen as the evaporation gas for the refrigerant and the liquefaction target, the liquefaction performance was confirmed to be almost the same as the value calculated in Experiment 1 regardless of the flow rate of the evaporation gas to be liquefied. That is, since the amount of evaporation gas consumed in the propulsion engine varies depending on the speed of the LNG carrier, the flow rate of the evaporative gas to be re-liquefied differs. When nitrogen is used as the evaporation gas for the refrigerant and the refill liquefaction, Liquefaction performance remained stable regardless of flow rate.

However, in the actual evaporation gas re-liquefaction system, when methane (that is, evaporation gas generated from an actual storage tank) is applied instead of nitrogen as the refrigerant and the liquid to be liquefied, the LNG carrier is in an anchored state, (Most of the evaporation gas from the LNG storage tank can be used as fuel at the highest operating speed), the re-liquefaction performance is almost similar to that of Experiment 1, but the highest operating speed When the ship is operated at 70% or less of the fuel consumption or when the ship is operated at a speed less than 70% of the fuel consumption, the re-liquefaction performance is less than 70% of the theoretical predicted value. The lower case was also confirmed. That is, when methane (that is, evaporation gas generated in an actual storage tank) is used instead of nitrogen as the refrigerant and the reflux gas to be refluxed, the re-liquefying performance does not reach the theoretical calculated value depending on the flow rate of the reflux gas to be refluxed There was a section that could not be done.

Specifically, a section where the re-liquefaction performance of the actual evaporation gas re-liquefaction system does not reach a theoretical calculated value will be described as follows.

1. An LNG carrier using a 25 MW ME-GI engine operating at a speed of 10 to 17 knots

2. Assuming that the flow rate of the evaporation gas generated in the storage tank is 3800 kg / h, the flow rate of the evaporation gas used as the fuel in the engine (ME-GI engine as the propulsion engine + DFDG as the power generation engine) 2660 kg / h

3. Assuming that the flow rate of the evaporation gas generated in the storage tank is 3800 kg / h, when the flow rate of the evaporative gas to be refixed is 1900 to 3300 kg / h

4. When the ratio of the flow rate of the evaporative gas to be reflocculated to the flow rate of the evaporation gas used as the refrigerant (which may include the gas component separated by the gas-liquid separator) is in the range of 0.42 to 0.72

There is a need to solve this problem because the amount of liquefaction actually measured in accordance with the operating conditions of the ship or the flow rate of the evaporation gas to be refloated is very different from the theoretical calculated value. If the amount of evaporative gas that can not be re-liquefied due to the low re-liquefaction performance is increased, there is a problem that additional measures are required, such as discharging the evaporated gas to the outside or burning it, wasting energy or re-liquefying it by a separate re-liquefaction cycle have. In this way, unlike nitrogen, the re-liquefaction performance of the evaporation gas differs greatly from the theoretical predicted value due to the difference in properties of nitrogen and evaporation gas.

It can be seen from the above results that even if the operating conditions of the LNG carrier are changed, that is, even if the flow rate of the evaporative gas to be reslurry varies, a step of stably maintaining the remigration performance is required.

Thus, in accordance with one aspect of the present invention, there is provided a method of compressing evaporative gas discharged from a storage tank to a high pressure, heat exchanging all or a portion of the high pressure compressed evaporative gas with evaporative gas discharged from the storage tank, Pressure gas injection engine including a high-pressure gas injection engine, the method comprising the steps of: operating the LNG carrier to change the operating condition of the LNG carrier or changing the flow rate of the evaporative gas to be re-liquefied, Pressure gas injection engine, comprising the steps of: providing a high-pressure gas-injection engine;

On the other hand, when the engine mounted on the LNG line is not a high-pressure gas injection engine but an engine using a relatively low-pressure evaporation gas as fuel, such as an X-DF engine, The present invention is advantageous in a case where the surplus evaporation gas passing through the liquefaction process is further pressurized and re-liquefied.

The re-liquefaction method is a method in which the LNG line is operated at a speed of 10 to 17 knots, the flow rate of the evaporative gas used as fuel in the engine (engine for propulsion + power generation) is 1100 to 2660 kg / It is preferable that the flow rate of the evaporation gas to be liquefied is 1900 to 3300 kg / h, or the flow rate of the evaporation gas to be resliced to the flow rate of the evaporation gas (which may include gas components separated by the gas-liquid separator) Is in the range of 0.42 to 0.72.

The step of stably maintaining the re-liquefaction performance is characterized in that the re-liquefaction performance is stably maintained even when the heat capacity ratio (Heat Capacity Ratio) of the heat exchanger is 0.7 to 1.2.

M1, the specific heat of the high-temperature fluid is c1, the flow rate of the low-temperature fluid (evaporation gas used as the refrigerant in the present invention) is m2, the flow rate of the low-temperature fluid When the specific heat is c2, the following equation is satisfied.

CR = (m1 x c1) / (m2 x c2)

In Experiment 2, when the amount of the evaporation gas used as the refrigerant (which may include the gas component generated from the gas-liquid separator) is kept constant and the amount of the evaporation gas to be re-liquefied changes, that is, The recooling performance is found to be less than the calculated value when m1 is changed, but also when the amount of the evaporation gas (which may include gas components generated from the gas-liquid separator) used as the refrigerant is varied , That is, even if m2 is changed in the above equation, the re-liquefaction performance does not reach the calculated value.

Therefore, the step of stably maintaining the liquefaction performance of the present invention can be carried out in such a manner that at least one of the amount of the evaporation gas (which may include the gas component generated from the gas-liquid separator) used as the refrigerant and the amount of the evaporation gas to be liquefied The liquefaction performance is stably maintained even when the heat capacity ratio of the heat exchanger is 0.7 to 1.2

In addition, the step of stably maintaining the liquefaction performance is characterized in that, in the calculation condition of the &quot; Experiment 1 &quot;, the liquefaction amount is maintained at 50% or more of the calculated value. Preferably 60% or more, more preferably 70% or more of the calculated value. When the liquefaction amount is less than 50% of the calculated value, there is a problem in that the evaporated gas remaining in the gas-fired unit (GCU) must be burned depending on the operating conditions during the operation of the LNG carrier.

Therefore, it can be understood from the above results that even if the operating conditions of the LNG carrier are changed, that is, even if the flow rate of the evaporative gas to be resuplicated fluctuates, a step of stably maintaining the resolidification performance is required.

Also, one of the reasons why the re-liquefaction performance is significantly different from the theoretical predicted value is that it is caused by a heat exchanger in which two or more blocks are combined.

The heat exchanger applied to the LNG carrier evaporation gas re-liquefaction system is produced by KOBELCO, ALFA Laval, Heatric, etc., which is advantageous when the evaporation gas to be re-liquefied is high pressure. Blocks are limited, so you need to combine two or more blocks.

10 is a schematic view of a conventional PCHE.

Referring to FIG. 10, a conventional PCHE includes a hot gas inlet pipe 110, a hot gas inlet header 120, a core 190, a hot fluid outlet header Hot A gas outlet header 130, a hot gas outlet pipe 140, a cold gas inlet pipe 150, a cold gas inlet header 160, A cold gas outlet header 170, and a cold gas outlet pipe 180.

The hot fluid supplied to the heat exchanger flows into the heat exchanger through the hot fluid inlet pipe 110 and is then dispersed by the hot fluid inlet header 120 and sent to the core 190. The high temperature fluid sent to the core 190 is heat exchanged with the low temperature fluid in the core 190 and cooled and then collected in the high temperature fluid discharge header 130 and discharged to the outside of the heat exchanger through the high temperature fluid discharge pipe 140.

The low-temperature fluid supplied to the heat exchanger is introduced into the heat exchanger through the low-temperature fluid inlet pipe 150 and then dispersed by the low-temperature fluid inlet header 160 and sent to the core 190. The low temperature fluid sent to the core 190 is used as the refrigerant of the heat exchange for cooling the high temperature fluid in the core 190 and then collected in the low temperature fluid discharge header 170 and passed through the low temperature fluid discharge pipe 180 to the outside of the heat exchanger .

The low temperature fluid used as the refrigerant in the heat exchanger of the present invention is the evaporated gas discharged from the storage tank (which may contain gas components separated by the gas-liquid separator), and the high temperature fluid cooled in the heat exchanger is compressed This is the evaporative gas to be resupplyed.

The core 190 may include a plurality of blocks (FIG. 10 shows a case including three blocks. Hereinafter, even in the case of the present invention, the case where the core of the heat exchanger includes three blocks However, when the core of the heat exchanger includes two or more blocks, there is a space between the blocks, and air filled in the spaces between the blocks serves as a heat insulating layer, The thermal conductivity is lowered.

Also, when the evaporation gas is used as the refrigerant, if the refrigerant first flows into any one of the blocks, the refrigerant supplied after the refrigerant first flows into the block in which the refrigerant first flows, and the temperature of the block in which the refrigerant first flows It becomes lower than other blocks.

If the phenomenon of the refrigerant leaning toward the block into which the refrigerant first flows and the phenomenon that the thermal conductivity between the blocks are lowered is caused, the temperature difference between the blocks becomes large, resulting in a decrease in the liquefaction performance. That is, even if the refrigerant is poured into one block, if the thermal conductivity between the blocks is good, the temperature difference between the blocks is not large, but if the air between the blocks serves as the heat insulating layer, the temperature difference between the blocks becomes large.

11 is a schematic view of a heat exchanger according to a first preferred embodiment of the present invention.

11, the heat exchanger of the present embodiment includes, in addition to the structure included in the conventional PCHE shown in FIG. 10, a first perforated plate 210 installed between the hot fluid inlet header 120 and the core 190 A second perforated plate 220 installed between the high temperature fluid discharge header 130 and the core 190, a third perforated plate 230 installed between the low temperature fluid inlet header 160 and the core 190, And a fourth perforated plate 240 installed between the cryogenic fluid discharge header 170 and the core 190.

The heat exchanger of the present embodiment is characterized in that it includes means for dispersing the fluid supplied to the heat exchanger or discharged from the heat exchanger, and means for resisting the flow of the fluid to disperse the fluid may be used. The perforated plates 210, 220, 230, and 240 of this embodiment are examples of a means for dispersing fluid or a means for providing resistance to the flow of fluid, and the heat exchanger of this embodiment is not limited to including a perforated plate.

The first perforated plate 210 is a plate member having the same size and shape as the cross section of the hot fluid inflow header 120, And the third perforated plate 230 may have a cross-section of the low-temperature fluid inlet header 160 and the second perforated plate 220 may have the same size and shape as the cross-section of the high- It is preferable that the fourth porous plate 240 has the same size and shape and the fourth porous plate 240 has the same size and shape as the cross-section of the low-temperature fluid discharge header 170.

The plurality of holes formed in the perforated plates 210, 220, 230, and 240 of the present embodiment may have the same cross-sectional area, and the cross-sectional area near the pipes 110, 140, 150, A hole with a larger cross-sectional area may be formed as the pipe 110, 140, 150, 180 is farther away.

The plurality of holes formed in the perforated plates 210, 220, 230, and 240 of this embodiment may be uniform in density and may be formed in the vicinity of the pipes 110, 140, 150, The density is low and the forming density can be increased as the distance from the pipes 110, 140, 150, and 180 is increased. A low forming density means that fewer holes are formed in the same area, and a high forming density means that more holes are formed in the same area.

The perforated plates 210, 220, 230, and 240 of the present embodiment are formed such that the fluid that has passed through the first perforated plate 210 and the third perforated plate 230 is effectively dispersed and introduced into the core 190 Or the core 190 so that the fluid discharged from the core 190 can be effectively dispersed and pass through the second perforated plate 220 and the fourth perforated plate 240. [ The distance between the perforated plates 210, 220, 230, 240 and the core 190 may be, for example, approximately 20 to 50 mm.

According to the heat exchanger of this embodiment, since the fluid is dispersed by at least one of the first to fourth perforated plates 210, 220, 230, and 240, the phenomenon of concentrating the refrigerant in any one of the blocks can be alleviated.

The heat exchanger according to the second preferred embodiment of the present invention further includes a first partition wall 210 provided between the first perforated plate 210 and the core 190, A second partition 320 disposed between the core 190 and the second perforated plate 220, a third partition 330 disposed between the third perforated plate 230 and the core 190, And a fourth partition wall 340 installed between the core 190 and the fourth perforated plate 240.

FIG. 12 is a schematic view of a first partition or a second partition included in a heat exchanger according to a second preferred embodiment of the present invention, FIG. 13 is a schematic view of a first partition and a second partition included in a heat exchanger according to a second preferred embodiment of the present invention, FIG. 14 is a schematic view of a second partition and a second perforated plate included in a heat exchanger according to a second preferred embodiment of the present invention. FIG.

The first to fourth partition walls 310, 320, 330, and 340 of the present embodiment prevent the fluid dispersed by the first to fourth perforated plates 210, 220, 230, and 240 from collecting again.

12 and 13, the first barrier rib 310 of the present embodiment may surround the rim of the first perforated plate 210 at a predetermined height, and may divide the enclosed inner space into a plurality of regions. 12 and 13 (a) show a shape in which the inner space surrounding the rim of the first perforated plate 210 at a certain height is divided into four, and FIG. 12 (b) shows a shape divided into eight.

The first partition wall 310 shown in Figs. 12 and 13 (b) has a structure in which the inner space surrounding the rim of the first perforated plate 210 at a predetermined height is formed in a one-directional grating It is not only divided by the grid, but also divided into grids in different directions. That is, in the first partition 310 shown in Figs. 12 and 13A, if the member dividing the inner space surrounding the rim of the first perforated plate 210 at a constant height is referred to as a vertical member 1, the first partition wall 310 shown in Figure 3B includes a plurality of horizontal members 2 dividing a space between the vertical members 1 as well as a plurality of vertical members 1, The grids intersect each other to divide the inner space.

As shown in FIGS. 12 and 13 (b), when the internal space of the first perforated plate 210 is further divided in the other direction, the fluid can be more dispersed, and in particular, It is possible to prevent the refrigerant from collecting again in one block.

In addition, when the inner space of the first perforated plate 210 is further divided in the other direction, there is an advantage that the first perforated plate 210 and the core 190 can maintain the spacing more reliably. In particular, it is possible to prevent the first perforated plate 210 from being bent and coming into contact with the core 190 due to the pressure of the fluid passing through the first perforated plate 210. If the first perforated plate 210 and the core 190 are in contact with each other, the fluid may not be properly supplied to the contacted portion, and the heat exchange efficiency may be lowered.

11 and 13, the high-temperature fluid introduced through the high-temperature fluid inlet pipe 110 passes through the high-temperature fluid inlet header 120, the first perforated plate 210, and the first partition wall 310 sequentially And then flows into the core 190.

Referring to FIGS. 12 and 14, the second partition 320 of the present embodiment may be configured to surround the rim of the second perforated plate 220 at a predetermined height and to divide the enclosed inner space into a plurality of regions. Figs. 12 and 14 (a) show a shape obtained by dividing the inner space surrounding the rim of the second perforated plate 220 at a constant height into four, and Fig. 8 (b) shows a shape divided into eight.

The second partition 320 shown in FIG. 12 and FIG. 14 (b) has a structure in which the inner space surrounding the rim of the second perforated plate 220 at a predetermined height is formed in a one-directional grating It is not only divided by the grid, but also divided into grids in different directions. That is, in the second partition 320 shown in Figs. 12 and 14A, if the member dividing the inner space surrounding the rim of the second perforated plate 220 at a certain height is referred to as a vertical member 1, the second partition 320 shown in Figure 2B includes a plurality of horizontal members 2 dividing a space between the vertical members 1 as well as a plurality of vertical members 1, The grids intersect each other to divide the inner space.

As shown in FIGS. 12 and 14 (b), if the internal space of the second perforated plate 220 is further divided in the other direction, the fluid can be dispersed even more, and in particular, It is possible to prevent the refrigerant from collecting again in one block.

In addition, when the inner space of the second perforated plate 220 is further divided in the other direction, there is an advantage that the second perforated plate 220 and the core 190 can maintain the spacing more reliably. Particularly, it is possible to prevent the second perforated plate 220 from being bent and coming into contact with the core 190 due to the pressure of the fluid passing through the second perforated plate 220. When the second perforated plate 220 and the core 190 are brought into contact with each other, the fluid may not be properly discharged to the contacted portion and the heat exchange efficiency may be lowered.

11 and 14, the high temperature fluid discharged from the core 190 passes through the second partition 320, the second perforated plate 220, and the high temperature fluid discharge header 130 in order, And is discharged through the pipe 140.

FIG. 15 is a schematic view of a third partition or a fourth partition included in the heat exchanger according to the second preferred embodiment of the present invention. FIG. 16 is a cross-sectional view of the third partition and the third partition, which are included in the heat exchanger according to the second preferred embodiment of the present invention. FIG. 17 is a schematic view of a fourth partition and a fourth perforated plate included in a heat exchanger according to a second preferred embodiment of the present invention. FIG.

Referring to FIGS. 15 and 16, the third partition wall 330 of the present embodiment may surround the rim of the third perforated plate 230 at a predetermined height, and may divide the enclosed inner space into a plurality of regions. In FIGS. 15 and 16A, the inner peripheries of the perforations of the third perforated plate 230 at a constant height are divided into four parts, and FIG. 16B shows a shape divided into eight parts.

The third partition wall 330 shown in Figs. 15 and 16 (b) is a partition wall in which the inner space surrounding the rim of the third perforated plate 230 at a certain height is arranged in a one-directional grating It is not only divided by the grid, but also divided into grids in different directions. That is, in the third partition wall 330 shown in Figs. 15 and 16A, if the member dividing the inner space surrounding the rim of the third perforated plate 230 at a predetermined height is referred to as a vertical member 1, the third partition wall 330 shown in Figure 3B includes a plurality of horizontal members 2 dividing a space between the vertical members 1 as well as a plurality of vertical members 1, The grids intersect each other to divide the inner space.

As shown in FIGS. 15 and 16 (b), when the internal space of the third perforated plate 230 is further divided in the other direction, the fluid can be more dispersed, and in particular, It is possible to prevent the refrigerant from collecting again in one block.

In addition, when the inner space of the third perforated plate 230 is further divided in the other direction, there is an advantage that the third perforated plate 230 and the core 190 can maintain the spacing more reliably. Particularly, it is possible to prevent the third perforated plate 230 from being bent and coming into contact with the core 190 due to the pressure of the fluid passing through the third perforated plate 230. If the third perforated plate 230 and the core 190 are in contact with each other, the fluid may not be properly supplied to the contacted portion and the heat exchange efficiency may be lowered.

11 and 16, the low-temperature fluid introduced through the low-temperature fluid inlet pipe 150 passes through the low-temperature fluid inlet header 160, the third perforated plate 230, and the third partition wall 330 sequentially And then flows into the core 190.

15 and 17, the fourth partition wall 340 of the present embodiment may be configured to surround the rim of the fourth perforated plate 240 at a predetermined height, and to divide the enclosed inner space into a plurality of regions. Figs. 15 and 17A show a configuration in which the inner space surrounding the rim of the fourth perforated plate 240 at a predetermined height is divided into four parts, and Fig. 15B shows a configuration divided into eight parts.

The fourth partition wall 340 shown in Figs. 15 and 17 (b) has a structure in which the inner space surrounding the rim of the fourth perforated plate 240 at a predetermined height is formed in a one-directional grating It is not only divided by the grid, but also divided into grids in different directions. That is, in the fourth partition wall 340 shown in Figs. 15 and 17A, if the member dividing the inner space surrounding the rim of the fourth perforated plate 240 at a constant height is referred to as a vertical member 1, the fourth partition wall 340 shown in Figure 4B includes a plurality of horizontal members 2 dividing a space between each of the vertical members 1 as well as a plurality of vertical members 1, The grids intersect each other to divide the inner space.

As shown in Figs. 15 and 17 (b), when the inner space of the fourth perforated plate 240 is further divided in the other direction, the fluid can be dispersed more evenly, and in particular, It is possible to prevent the refrigerant from collecting again in one block.

In addition, when the inner space of the fourth perforated plate 240 is further divided in the other direction, there is an advantage that the fourth perforated plate 240 and the core 190 can maintain a better separation. Particularly, it is possible to prevent the fourth perforated plate 240 from being bent and coming into contact with the core 190 due to the pressure of the fluid passing through the fourth perforated plate 240. When the fourth perforated plate 240 and the core 190 are in contact with each other, the fluid may not be properly discharged to the contacted portion and the heat exchange efficiency may be lowered.

11 and 17, the low temperature fluid discharged from the core 190 passes through the fourth partition wall 340, the fourth perforated plate 240, and the low temperature fluid discharge header 170 in order, And discharged through the pipe 180.

FIG. 18A is a schematic view showing a refrigerant flow of a conventional heat exchanger, FIG. 18B is a schematic view showing a refrigerant flow of the heat exchanger according to the first preferred embodiment of the present invention, FIG. FIG. 3 is a schematic view showing a refrigerant flow of a heat exchanger according to a second preferred embodiment of the present invention. FIG.

18 (a), in the conventional heat exchanger, it can be seen that the low-temperature fluid introduced into the low-temperature fluid inflow pipe 150 is concentrated and supplied to the middle block close to the low-temperature fluid inflow pipe 150 have. In the case of the conventional heat exchanger having three blocks, approximately 70% of the refrigerant is supplied to the middle block close to the low temperature fluid inlet pipe 150, and approximately 15% of the refrigerant is supplied to the remaining blocks, The difference was confirmed to be more than four times.

18 (b), in the case of the heat exchanger of the first embodiment of the present invention, the low temperature fluid introduced into the low temperature fluid inlet pipe 150 is dispersed by the third perforated plate 230, It can be seen that each block is uniformly flowed into a relatively large number of blocks. However, it can be seen that there is still some degree of concentration of the low-temperature fluid in the block near the low-temperature fluid inflow pipe 150.

18 (c), in the case of the heat exchanger of the second embodiment of the present invention, the low temperature fluid introduced into the low temperature fluid inlet pipe 150 is dispersed by the third perforated plate 230, The heat exchanger 330 is more uniformly introduced into the plurality of blocks than the conventional heat exchanger, and flows more evenly than the heat exchanger of the first embodiment.

The heat exchanger of the present embodiment is characterized in that the difference in flow rate of the fluid discharged from each of the plurality of blocks or each of the plurality of blocks is less than four times.

Fig. 19 (a) is a schematic view showing the position of a temperature sensor installed for measuring the internal temperature of the heat exchanger, Fig. 19 (b) is a graph showing the temperature inside the heat exchanger measured by the temperature sensor FIG. The graph (1) shown in FIG. 19 (b) shows the temperature distribution inside the conventional heat exchanger, and the graph shows the temperature distribution inside the heat exchanger according to the second preferred embodiment of the present invention .

Referring to FIG. 19 (b), in the case of the conventional heat exchanger, the temperature of the middle block is much lower than the temperature of the other blocks, so that a large temperature difference between a plurality of blocks can be confirmed. In the case of a conventional heat exchanger, it has been confirmed that the temperature difference between the lowest temperature portion and the lowest temperature portion is approximately 130 to 140 degC.

On the other hand, in the case of the heat exchanger of the second embodiment, it can be confirmed that the temperature difference between a plurality of blocks is relatively small. In the case of the heat exchanger of this embodiment, it was confirmed that the temperature difference between the lowest temperature portion and the highest temperature portion was about 40 to 50 degC, which is lower than that of the conventional heat exchanger.

According to the present invention, even when the evaporator is used as the refrigerant of the heat exchanger and the heat exchanger includes a plurality of blocks, it is possible to maintain the flow rate of the refrigerant supplied to each block relatively uniformly, So that stable re-liquefaction performance can be secured even when the flow rate of the evaporative gas to be re-liquefied is changed.

On the other hand, the perforated plate may be made of SUS material and may be shrunk due to contact with the cryogenic evaporation gas, and then returned to the original state after the refrigerant passes through. When the perforated plate is welded to the heat exchanger, the heat exchanger having a large heat capacity is not shrunk even when brought into contact with the evaporation gas, and the perforated plate having a small heat capacity is in contact with the evaporation gas Since the degree of shrinkage is large, the perforated plate may be broken.

Therefore, it is necessary to bond the perforated plate to the heat exchanger so as to be able to relieve heat expansion and contraction. In the fourth and fifth preferred embodiments of the present invention, an example of the perforated plate combined to enable heat expansion and contraction is described.

FIG. 20 is a schematic view showing a part of a heat exchanger according to a third preferred embodiment of the present invention, and FIG. 21 is an enlarged schematic view of part A of FIG.

In addition to the structure included in the conventional PCHE shown in FIG. 10, the heat exchange pipe of the present embodiment, as in the first embodiment, includes a first perforated plate (not shown) installed between the hot fluid inlet header 120 and the core 190 A second perforated plate 220 installed between the high temperature fluid discharge header 130 and the core 190, a third perforated plate 230 installed between the low temperature fluid inlet header 160 and the core 190, And a fourth perforated plate 240 installed between the low temperature fluid discharge header 170 and the core 190. [

20 and 21, the fourth perforated plate 240 of this embodiment is installed in the low-temperature fluid discharge header 170, in which the fourth perforated plate 240 is directly welded to the low-temperature fluid discharge header 170 Two support members 420 are spaced apart and welded to the low temperature fluid discharge header 170 and the fourth perforated plate 240 is sandwiched between the two support members 420.

Since the fourth perforated plate 24 is sandwiched between the two support members 420 and is not completely fixed, the fourth perforated plate 24 is not bent or broken even if it contracts due to contact with the evaporation gas at cryogenic temperatures, It does not.

The support member 420 is preferably of a minimum size such that the fourth perforated plate 240 can accommodate the contraction, and the interval between the support members 420 is preferably such that the fourth perforated plate 240 moves a little It is preferable that the distance is as small as possible.

Similar to the fourth perforated plate 240, the first perforated plate 210, the second perforated plate 210, and the third perforated plate 230 of the present embodiment are spaced apart from each other by a predetermined distance, The second perforated plate 220 is sandwiched between two support members welded at regular intervals to the hot fluid discharge header 130 and the third perforated plate 230 is sandwiched between the two support members, And is sandwiched between two support members welded at regular intervals to the low temperature fluid inlet header 160.

FIG. 22 is a schematic view showing a part of a heat exchanger according to a fourth preferred embodiment of the present invention, and FIG. 23 is an enlarged schematic view of a part B in FIG.

In addition to the structure included in the conventional PCHE shown in FIG. 10, the heat exchange pipe of the present embodiment, as in the first embodiment, includes a first perforated plate (not shown) installed between the hot fluid inlet header 120 and the core 190 A second perforated plate 220 installed between the high temperature fluid discharge header 130 and the core 190, a third perforated plate 230 installed between the low temperature fluid inlet header 160 and the core 190, And a fourth perforated plate 240 installed between the low temperature fluid discharge header 170 and the core 190. [

Referring to FIGS. 22 and 23, the fourth perforated plate 240 of this embodiment is provided in the low-temperature fluid discharge header 170 as in the third embodiment, but is directly welded to the low- It is not.

However, unlike the third embodiment, the fourth perforated plate 240 of this embodiment has both ends extending parallel to the core 190 and having a stepped shape in a direction away from the core 190, And is sandwiched between one support member 420 and the core 190, rather than being sandwiched between the members 420.

That is, one support member 420 is welded 410 to the low temperature fluid discharge header 170 at a certain distance from the core 190, and the fourth perforated plate 240, which extends parallel to the core 190, And the fourth perforated plate 240 is sandwiched between the supporting member 420 and the core 190 and is separated from the core 190 from both ends As shown in Fig.

Since the fourth perforated plate 24 of this embodiment is sandwiched between the support member 420 and the core 190 and is not completely fixed, even if the fourth perforated plate 24 shrinks due to contact with the extremely low temperature evaporated gas, And the connecting portion is not damaged.

The support member 420 of this embodiment is preferably of a minimum size such that the fourth perforated plate 240 can accommodate the contraction and the interval between the support member 420 and the core 190 is also preferably the same as that of the fourth perforated plate 240 ) Is preferably a minimum distance that allows some movement due to shrinkage. Both ends of the fourth perforated plate 240 extending parallel to the core 190 can be sandwiched between the support member 420 and the core 190 and can have a minimum length .

Similarly to the fourth perforated plate 240, the first through third perforated plates 210, 220, and 230 of the present embodiment are formed so that both ends extend in parallel with the core 190, The first perforated plate 210 is sandwiched between the support member welded to the hot fluid inlet header 120 and the core 190 and the second perforated plate 220 is sandwiched between the hot fluid outlet header 130 And the third perforated plate 230 is sandwiched between the support member welded to the low-temperature fluid inflow header 160 and the core 190 so that both end portions are sandwiched between the support member and the core 190, Loses.

24 (a) is a schematic view of the overall shape of the heat exchanger, (b) is a schematic view of the block, and (c) is a schematic view of the channel plate. The block shown in FIG. 5 (b) may be a diffusion block.

Referring to Figure 24, a core 190 in which heat exchange occurs between a cryogenic fluid and a hot fluid is comprised of a plurality of blocks 192, and the block 192 includes a plurality of channel plates 194 for cryogenic fluids, And the channel plate 196 for the channel plate 196 are alternately stacked. A plurality of channels through which fluid flows are formed in each of the channel plates 194 and 196.

25 (a) is a schematic view of the channel plate for low-temperature fluid shown in FIG. 24 (c) viewed in the direction C, FIG. 25 (b) is a schematic view of a channel of the channel plate for low-temperature fluid in a conventional heat exchanger (c) is a schematic view of a channel of a channel plate for a low temperature fluid of a heat exchanger according to a fifth preferred embodiment of the present invention, Lt; / RTI &gt; is a schematic view of the channel of the plate.

Referring to FIG. 25, the channels 198 engraved in the channel plate are generally uniform in width and straight as shown in (a), and the heat exchange according to the fifth and sixth preferred embodiments of the present invention The vessel includes a channel shaped to resist the fluid.

Referring to FIG. 25 (c), the heat exchanger of the fifth embodiment includes a plurality of channels 198 whose widths are narrower than the widths of the other portions. That is, the channel 198 of this embodiment is formed such that the cross-sectional area of the channel 198 when viewed from the direction C in FIG. 24C is smaller than that of the other portions.

If the cross-sectional area of the inlet portion of the channel 198 is made small, the flow of the introduced fluid is resisted and the flow is dispersed, and the concentration of the fluid in any one of the plurality of blocks can be mitigated or prevented.

Referring to FIG. 25 (d), the heat exchanger of the fifth embodiment includes a plurality of zigzag shaped channels 198. When the channel 198 is formed in a zigzag shape, the fluid receives resistance and the flow is dispersed, and the concentration of the fluid in any one of the plurality of blocks can be mitigated or prevented.

According to the heat exchanger of the fourth and fifth embodiments of the present invention, since the channel includes a shape capable of imparting a resistance to the fluid, the refrigerant is concentrated in any one block without adding a separate member for dispersing the fluid There is an advantage that the phenomenon can be mitigated or prevented.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. It is.

10: compressor 20: heat exchanger
30: Decompression device 40: Gas-liquid separator
110: High temperature fluid inlet pipe 120: High temperature fluid inlet header
130: high temperature fluid discharge header 140: high temperature fluid discharge pipe
150: Low temperature fluid inlet pipe 160: Low temperature fluid inlet header
170: Low temperature fluid discharge header 180: Low temperature fluid discharge pipe
190: core 192: block
194: Channel plate for low temperature fluid 196: Channel plate for high temperature fluid
198: Channels 210, 220, 230, 240: Perforated plate
310, 320, 330, 340: partition wall 420: support member

Claims (9)

A heat exchanger for exchanging a high-temperature fluid, which is an evaporation gas compressed by a compressor, with a low-temperature fluid, which is an evaporation gas before being compressed by the compressor, after being discharged from the LNG storage tank; And
And expansion means for expanding the fluid cooled by the heat exchanger,
The heat exchanger
A core generating heat exchange between the high temperature fluid and the low temperature fluid; And
And fluid distributing means for dispersing the fluid flowing into the core or the fluid discharged from the core,
The core comprises:
A plurality of blocks; And
And an insulating layer between the plurality of blocks,
Wherein the fluid dispersing means is coupled to the heat exchanger so that heat expansion and contraction can be eliminated. The method according to claim 1,
Wherein the fluid dispersing means imparts resistance to the fluid to disperse the fluid. The method of claim 2,
Wherein the fluid dispersion means is a perforated plate. The method according to any one of claims 1 to 3,
The heat exchanger includes a support member spaced apart from each other by a predetermined distance and coupled to the heat exchanger,
Wherein said fluid dispersion means is sandwiched between said spaced apart support members. The method of claim 4,
The heat exchanger
At least one header for sending the fluid flowing into the heat exchanger to the core or discharging the fluid discharged from the core to the outside of the heat exchanger,
Wherein the support member is coupled to the header. The method according to any one of claims 1 to 3,
Wherein the heat exchanger includes a support member spaced apart from the core by a predetermined distance and coupled to the heat exchanger,
Wherein the fluid dispersion means is sandwiched between the core and the support member. The method of claim 6,
Wherein the fluid dispersing means is shaped like a staggered shape in a direction in which both ends extend parallel to the core and away from the core. The method of claim 6,
The heat exchanger
At least one header for sending the fluid flowing into the heat exchanger to the core or discharging the fluid discharged from the core to the outside of the heat exchanger,
Wherein the support member is coupled to the header. A heat exchanger for exchanging a high-temperature fluid, which is an evaporation gas compressed by a compressor, with a low-temperature fluid, which is an evaporation gas before being compressed by the compressor, after being discharged from the LNG storage tank; And
And expansion means for expanding the fluid cooled by the heat exchanger,
The heat exchanger
A plurality of blocks generating heat exchange between the high-temperature fluid and the low-temperature fluid; and a heat insulating layer between the plurality of blocks;
Fluid distributing means for dispersing a fluid flowing into the core or a fluid discharged from the core; And
At least one header for sending the fluid flowing into the heat exchanger to the core or discharging the fluid discharged from the core to the outside of the heat exchanger,
Wherein the fluid dispersion means is coupled to the header so as to be movable.

Images