KR101950347B1 - Device for measuring liquid level of low temperature liquefied gas and pressurized vessel for low temperature liquefied gas equipped with the same - Google Patents

Abstract

A liquid level measuring apparatus for low temperature liquefied gas and a pressure vessel for low temperature liquefied gas equipped with the apparatus. A liquid level measuring apparatus for a low temperature liquefied gas, which is configured to be installed in a container filled with a low temperature liquefied gas, includes: a liquid inlet hole configured to pass liquid when installed in the container but not to allow gas to pass therethrough; A gas discharge hole configured to allow gas to pass therethrough but not to allow liquid to pass therethrough, an evaporation container communicating with the liquid inlet hole and the gas discharge hole, a first pressure signal transfer pipe configured to communicate with the evaporation passage, And a second pressure signal transfer pipe connected to the first pressure signal transfer pipe at one end and connected to the second pressure signal transfer pipe at the other end, Wherein the pressure differential liquid level system comprises a pressure P1 transmitted through the first pressure signal transmission line, And the pressure difference DELTA P between the pressures P2 transmitted through the two pressure signal transfer pipes is measured to calculate the liquid level of the low temperature liquefied gas filled in the vessel.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level measuring apparatus for low temperature liquefied gas and a pressure vessel for low temperature liquefied gas equipped with the apparatus,

A liquid level measuring apparatus for low temperature liquefied gas and a pressure vessel for low temperature liquefied gas equipped with the apparatus. More particularly, the present invention relates to a liquid level measurement apparatus for low temperature liquefied gas having means for detecting the liquid portion pressure of a low temperature liquefied gas and a pressure vessel for a low temperature liquefied gas equipped with the apparatus.

Conventional liquid level measuring apparatuses for low temperature liquefied gas have problems of low measurement accuracy, high manufacturing cost and high operation cost, and / or low structural stability.

1 is a view schematically showing a conventional liquid level measuring apparatus 10 for low temperature liquefied gas and a pressure vessel V for a low temperature liquefied gas equipped with the apparatus.

1 includes a pair of nozzles 11-1 and 11-2, a pair of shutoff valves 12-1 and 12-2, a pair of pressure signal transfer pipes 13- 1 and 13-2, a purge gas valve 14, a purge gas flow meter 15 and a differential pressure type liquid level meter 16.

Referring to FIG. 1, a low-temperature liquefied gas is filled in a pressure vessel V, and the low-temperature liquefied gas is composed of a liquid phase portion L _P and a vapor phase portion V _P which is in phase with the liquid phase portion L _P. The interface (I) between the liquid portion (L _P ) and the vapor portion (V _P ) is referred to as a liquid level. The outer wall of the pressure vessel V is surrounded by a heat insulating material IM to prevent heat input and output and to reduce the cold energy loss of the pressure vessel V. [

The nozzle 11-1 includes a liquid passage R _L and the nozzle 11-2 includes a gas passage R _V.

The pair of shutoff valves 12-1 and 12-2 is always open when the factory in which the pressure vessel V is installed is operated and only during maintenance of the pressure vessel V and the differential pressure level meter 16 Lt; / RTI >

The liquid level measuring apparatus 10 for low temperature liquefied gas is provided with an outside purge gas (PG) in the pressure signal transfer pipe (13-1) to prevent liquid from flowing into the pressure signal transfer pipe (13-1) Is continuously injected through the purge gas valve 14 and the purge gas flow meter 15.

The apparatus 10 for measuring the liquid level of the low-temperature liquefied gas finds a purge gas supply source which is good in accuracy and stability but has sufficient pressure to purge without causing problems in process performance and quality of the storage material (that is, low-temperature liquefied gas) There is a problem that it is not easy. In addition, the apparatus 10 is not widely used because it is expensive, such as a purge gas valve 14, a purge gas flow meter 15 and a purge gas supply pipe (indicated by arrows).

2A is a schematic view of a conventional low-temperature liquefied gas liquid level measuring apparatus 20 and a low-temperature liquefied gas pressure vessel V equipped with the same, and Fig. 2B is an enlarged view of a portion A in Fig. 2A to be.

The liquid level measuring apparatus 20 for low temperature liquefied gas in FIG. 2A includes a pair of nozzles 21-1 and 21-2, a pair of shutoff valves 22-1 and 22-2, a pair of pressure signal transfer pipes 23- 1 and 23-2, a differential pressure type liquid level meter 24, and a cap 25.

2A and 2B, a low temperature liquefied gas is filled in a pressure vessel V, and the low temperature liquefied gas is composed of a liquid phase portion L _P and a vapor phase portion V _P which is in phase with the liquid phase portion L _P . The interface (I) between the liquid portion (L _P ) and the vapor portion (V _P ) is referred to as a liquid level. The outer wall of the pressure vessel (V) is surrounded by a heat insulating material (IM) in order to block heat input and output and to reduce cold and heat loss of the pressure vessel (V).

The nozzle 21-1 includes a liquid passage R _L and the nozzle 21-2 includes a gas passage R _V.

The liquid level measuring apparatus 20 for low temperature liquefied gas is configured to cover the cap 25 at the end of the liquid passage R _L included in the nozzle 21-1 so that the liquid in the liquid portion L _P flows through the pressure signal transfer pipe 23- 1). This apparatus 20 has a simple structure and a low ratio of the auxiliary apparatus, but it is likely that a large amount of liquid may flow into the pressure signal transfer pipe 23-1 when the liquid sloshing occurs severely or the liquid level fluctuation is severe, The accuracy and stability of the system is greatly reduced. A heating means (not shown) such as an electric heating line is additionally provided in the pressure signal transmission pipe 23-1 to evaporate the liquid that has entered the pressure signal transmission pipe 23-1, Although it is possible to reduce the time taken to recover from the state of being filled with the gas, in this case, there is a disadvantage that stability in terms of structure is deteriorated.

3A is a schematic view of a conventional low-temperature liquefied gas liquid level measuring apparatus 30 and a low-temperature liquefied gas pressure vessel (V) equipped with the same, and FIG. 3B is an enlarged view to be.

The liquid level measuring apparatus 30 for low temperature liquefied gas in FIG. 3A includes a pair of nozzles 31-1 and 31-2, a pair of shutoff valves 32-1 and 32-2, a pair of pressure signal transfer pipes 33- 1 and 33-2, a differential pressure type liquid level meter 34 and a heating means 35.

Referring to FIG. 3A, the pressure vessel V is filled with a low-temperature liquefied gas, and the low-temperature liquefied gas is composed of a liquid phase portion L _P and a vapor phase portion V _P which is phase-balanced with the liquid phase portion L _P. The interface (I) between the liquid portion (L _P ) and the vapor portion (V _P ) is referred to as a liquid level. The outer wall of the pressure vessel (V) is surrounded by a heat insulating material (IM) in order to block heat input and output and to reduce cold and heat loss of the pressure vessel (V).

The nozzle 31-1 includes a liquid passage R _L and the nozzle 31-2 includes a gas passage R _V.

The liquid level measuring apparatus 20 for low temperature liquefied gas in FIG. 2A is configured such that if all the liquid introduced into the pressure signal transfer pipe 23-1 is not evaporated and returned to the pressure vessel V in a gaseous state, 1) can not be restored to the state filled with the gas again, so that it takes a considerable time to stabilize when the liquid enters the pressure signal transfer pipe 23-1.

To overcome this disadvantage, the low temperature liquefied gas liquid level measuring apparatus 30 of Fig. 3A is configured such that no cap is installed at the end of the nozzle 31-1. The apparatus 30 includes a nozzle 31-1 and a shut-off valve (not shown) provided in the nozzle 31-1 to prevent a liquid from flowing into the small-diameter pressure signal transfer pipe 33-1 and causing a measurement error And a heating means 35 is installed in the pressure signal transfer pipe 33-1 so as to vaporize a sufficient amount of liquid and return it to the pressure vessel V at all times.

3A and 3B, the liquid level measuring apparatus 30 for cryogenic liquefied gas is configured such that the liquid introduced into the pressure signal transfer pipe 33-1 is returned to the pressure vessel V together with the vaporized gas VD So that the accuracy and stability of the liquid level measurement are improved to some extent, but there is a disadvantage in that the cooling loss is excessive and the ratio of the auxiliary device such as the heating means 35 is large.

4 is a view schematically showing a conventional low temperature liquefied gas liquid level measuring apparatus 40 and a pressure vessel V for a low temperature liquefied gas equipped with the same.

The liquid level measuring apparatus 40 for low temperature liquefied gas is disclosed in CN 102519543 A.

4 includes a pair of nozzles 41-1 and 41-2, a pair of pressure signal transmission pipes 42-1 and 42-2, a pressure differential liquid level meter 43, And a cap 44.

Referring to FIG. 4, the pressure vessel V is filled with a low-temperature liquefied gas, and the low-temperature liquefied gas is composed of a liquid phase portion L _P and a vapor phase portion V _P which is in phase with the liquid phase portion L _P. The interface (I) between the liquid portion (L _P ) and the vapor portion (V _P ) is referred to as a liquid level.

The liquid level measuring apparatus 40 of the low temperature liquefied gas in FIG. 4 is provided with a gas-liquid outlet hole h having a small diameter in order to restrict the amount of liquid that can flow into the nozzle 41-1 by the liquid- One or more. The device (40) has a disadvantage in that accuracy and stability of measurement are inferior when the liquid is sluggish or the liquid level fluctuation speed is high because the liquid is drawn through the same passage as the gas-liquid access hole (h) or the evaporated gas must be discharged. The device 40 is developed for a low-temperature liquefied gas storage tank having a comparatively small liquid sluggishness and a liquid level fluctuation rate, and is not suitable for measuring the liquid level of a process pressure vessel having a large liquid sloshing and a large liquid-phase fluctuation speed .

An embodiment of the present invention provides an apparatus for measuring the liquid temperature of a low-temperature liquefied gas, comprising means for detecting a liquid-phase pressure of a low-temperature liquefied gas boiling at room temperature.

There is provided a pressure vessel for a low-temperature liquefied gas equipped with the apparatus for measuring the liquid level of the low-temperature liquefied gas of the present invention.

According to an aspect of the present invention,

A liquid level measuring apparatus for low temperature liquefied gas, which is configured to be installed in a container filled with low temperature liquefied gas,

A liquid inlet configured to pass liquid when installed in the vessel but not to allow gas to pass;

A gas discharge hole configured to pass the gas but not to allow the liquid to pass therethrough when installed in the vessel;

An evaporation cylinder communicating with the liquid inlet and the gas outlet, respectively;

A first pressure signal transmission pipe configured to communicate with the evaporation passage;

A second pressure signal transmission pipe configured to communicate with a vapor phase portion in the vessel to be filled in the vessel when installed in the vessel; And

Wherein the first pressure signal transmission line is connected to the first pressure signal transmission line and the other end is connected to the second pressure signal transmission line,

The differential pressure liquid level is measured by measuring a pressure difference? P between a pressure P1 transmitted through the first pressure signal transmitting tube and a pressure P2 transmitted through the second pressure signal transmitting tube, Temperature liquefied gas, the low-temperature liquefied gas being configured to calculate a liquid level of the low-temperature liquefied gas.

The liquid inlet hole may be located lower than the gas outlet hole.

The evaporator may be configured to evaporate the introduced low temperature liquefied gas when the low temperature liquefied gas is introduced into the evaporator.

The liquid level measuring apparatus of the low temperature liquefied gas includes a first nozzle communicating with the evaporation passage, a second nozzle communicating with the second pressure signal transfer pipe, a first shutoff valve opening and closing the first nozzle, The second shut-off valve.

The evaporator may be configured to be closely inserted into the first nozzle.

Both the liquid inlet hole and the gas discharge hole may be formed in the evaporator.

The apparatus for measuring liquid level of the low temperature liquefied gas may further include a heating means for heating the evaporator.

The liquid level measuring apparatus of the low temperature liquefied gas may further include a magnetic purge flow rate adjusting plate disposed between the first nozzle and the evaporator, and the liquid inlet and the gas discharging hole may be formed in the self purge flow rate adjusting plate have.

Wherein the liquid level measuring device for low temperature liquefied gas further comprises a liquid inflow pipe communicating with the evaporation passage and a magnetic purge flow rate adjusting plate disposed between the liquid inflow pipe and the evaporator, May be formed in the magnetic purge flow rate regulating plate.

According to another aspect of the present invention,

There is provided a pressure vessel for low-temperature liquefied gas equipped with a liquid level measuring apparatus for the low temperature liquefied gas.

Wherein the pressure vessel for low-temperature liquefied gas has a single wall, and a pair of holes are formed at one side of the single wall, wherein the low-temperature liquefied gas liquid- And can be configured to communicate with the container through a pair of holes.

Wherein the pressure vessel for low-temperature liquefied gas has a double wall including an inner wall and an outer wall, the inner wall and the outer wall each including at least one hole, and at least a part of the liquid- And the liquid level measuring device for the low-temperature liquefied gas may be configured such that at least a portion of the low-temperature liquefied gas passes through the respective holes and is mounted in the pressure vessel for the low temperature liquefied gas.

The pressure vessel for the low temperature liquefied gas may be a pressure vessel.

The temperature of the low-temperature liquefied gas may be 0 ° C or lower.

The apparatus for measuring the liquid temperature of a low-temperature liquefied gas according to an embodiment of the present invention can solve various problems caused by characteristics of a liquid to boil and vaporize at room temperature, thereby securing the stability, reliability and accuracy of liquid level measurement, It is possible to minimize the heat loss and the cost of the apparatus.

However, the conventional technique used for measuring the liquid level of the low-temperature liquefied gas using the differential pressure liquid level has various problems, in particular, stability and reliability of the liquid level measurement are inferior. In order to overcome such problems, conventionally, an expensive diaphragm-capillary differential pressure gauge or a radar type liquid gauge has been used instead of a general pressure gauge liquid gauge. However, the diaphragm-capillary differential pressure type liquid level system is not only expensive, but also has other disadvantages such as limited use temperature at -40 ° C or higher due to the freezing point of the filling liquid, accuracy in measurement and mechanical reliability are poor. In addition, the radar type liquid level system is very expensive especially when the measurement liquid level span is large, and when the outside of the liquid level system is not completely insulated, the accuracy of the measurement due to gas bubbles .

1 is a schematic view of a conventional external gas purging differential pressure liquid level measuring apparatus and a pressure vessel for a low temperature liquefied gas equipped with the same.
FIG. 2A schematically shows a conventional cap type differential pressure level measuring apparatus and a pressure vessel for a low temperature liquefied gas equipped with the cap type differential pressure type liquid level measuring apparatus.
FIG. 2B is an enlarged view of a portion A in FIG. 2A.
3A is a view schematically showing a conventional heating type differential pressure liquid level measuring apparatus and a pressure vessel for a low temperature liquefied gas equipped with the same.
FIG. 3B is an enlarged view of a portion A in FIG. 3A.
4 is a view schematically showing a conventional improved cap type differential pressure liquid level measuring apparatus and a pressure vessel for a low temperature liquefied gas equipped with the same.
FIG. 5 is a conceptual diagram for explaining the operation principle of the apparatus for measuring a liquid temperature of a low-temperature liquefied gas according to an embodiment of the present invention and the pressure vessel for a low temperature liquefied gas equipped with the apparatus.
FIG. 6 is a schematic view of a liquid level measuring apparatus for low temperature liquefied gas according to the first embodiment of the present invention and a pressure vessel for a low-temperature liquefied gas equipped with the apparatus.
7 is a schematic view of an apparatus for measuring the liquid level of a low temperature liquefied gas according to a second embodiment of the present invention and a pressure vessel for a low temperature liquefied gas equipped with the apparatus.
FIG. 8 is a schematic view of an apparatus for measuring liquid level of a low temperature liquefied gas according to a third embodiment of the present invention and a pressure vessel for a low temperature liquefied gas equipped with the apparatus.
FIG. 9 is a detailed view of a magnetic purge flow rate regulating plate provided in the low temperature liquefied gas liquid level measuring apparatus of FIG.
10 is a schematic view of an apparatus for measuring a liquid temperature of a low temperature liquefied gas according to a fourth embodiment of the present invention and a pressure vessel for a low temperature liquefied gas equipped with the apparatus.

Next, an apparatus for measuring the liquid level of a low temperature liquefied gas according to an embodiment of the present invention and a pressure vessel for a low temperature liquefied gas equipped with the apparatus will be described in detail.

As used herein, the term " liquid level " means the height of the low temperature liquefied gas.

In the present specification, the term "low temperature liquefied gas" means a gas state at room temperature (10 to 40 ° C) such as ethane or propane, but is phase-converted into a liquid state when compressed, It evaporates naturally from the liquid state to the gaseous state due to the difference from the temperature.

As used herein, the term " purge gas " refers to a gas filling the evaporation cylinder and the pressure signal transfer tube communicated therewith.

In this specification, the term " liquid part " means a portion occupied by liquid in a pressure vessel filled with a low temperature liquefied gas.

In this specification, the term "gas part" means a portion occupied by gas in a pressure vessel filled with a low-temperature liquefied gas.

Also, in this specification, "A is located lower than B" means that A is located in the gravity direction relative to B, and B is located in the reverse direction of gravity relative to A.

As used herein, the term " pressurized vessel " refers to any vessel containing a low temperature liquefied gas at a constant pressure including atmospheric pressure.

An apparatus for measuring the liquid temperature of a low-temperature liquefied gas according to an embodiment of the present invention is an apparatus configured to be installed in a container filled with a low temperature liquefied gas.

5 is a conceptual diagram for explaining the operation principle of an apparatus 50 for measuring liquid level of a low temperature liquefied gas according to an embodiment of the present invention and a pressure vessel V for a low temperature liquefied gas equipped with the apparatus.

5, the liquid level measuring apparatus 50 for low temperature liquefied gas includes a liquid inlet port h _L , a gas outlet port h _v , an evaporator 51, a first pressure signal transfer pipe 52-1, A second pressure signal transfer pipe 52-2, and a differential pressure level meter 53, LT.

The liquid inlet port h _L and the gas outlet port h _v are formed in the evaporator 51, respectively. However, the present invention is not limited thereto.

The liquid inlet hole h _L is configured to pass the liquid but not the gas when the container V is installed.

The gas discharging hole (h _V ) is configured to pass the gas but not the liquid when it is installed in the vessel (V).

Adjustment of the height difference (ΔH) between the liquid suction hole (h _L) of the diameter of the gas discharging hole (h _V) of the diameter, the liquid suction hole (h _L) and a gas discharge hole (h _V), the liquid suction flow rate and the purge The gas flow rate can be adjusted accurately. Therefore, the coolant loss can be minimized by controlling the purge gas flow rate in accordance with the demand of the liquid level change sensing speed.

The evaporation chamber 51 communicates with the liquid inlet hole h _L and the gas outlet hole h _v , respectively.

The evaporation cylinder 51 serves to evaporate the liquid (that is, low-temperature liquefied gas) flowing into the evaporation cylinder 51 through the liquid inlet hole h _L using heat in the air and / or a heating means. That is, when an excess amount of liquid exceeding the normal flow rate momentarily enters the liquid level measuring apparatus 50 of the low temperature liquefied gas by the liquid swirling, the evaporation cylinder 51 is connected to the pressure signal transmitting pipe 52-1 of small diameter, And prevents pressure measurement errors from occurring. In addition, it also functions as a buffer chamber for preventing the liquid from being slammed and being directly sensed by the pressure fluctuation to prevent noise from being generated in the measured liquid level.

The first pressure signal transmission pipe (52-1) is configured to communicate with the evaporator (51).

The second pressure signal transmission pipe 52-2 is configured to communicate with the vapor phase portion V _P in the container V filled in the container V when the container V is installed in the container V.

The first pressure signal transmission pipe 52-1 and the second pressure signal transmission pipe 52-2 may each be in the form of a tube.

The differential pressure level meter 53 has one end connected to the first pressure signal transmission pipe 52-1 and the other end connected to the second pressure signal transmission pipe 52-2.

The differential pressure liquid level sensor 53 measures the pressure difference between the pressure P1 transmitted through the first pressure signal transmitting pipe 52-1 and the pressure P2 transmitted through the second pressure signal transmitting pipe 52-2 (I) of the low-temperature liquefied gas to be filled in the vessel (V) by measuring the pressure difference (DELTA P).

Although not specifically shown in FIG. 5, the differential pressure level meter 53 may include a differential pressure transmitter and a pressure-to-height converter.

The differential pressure transmitter transmits the pressure difference AP between the pressure P1 transmitted through the first pressure signal transmitting pipe 52-1 and the pressure P2 transmitted through the second pressure signal transmitting pipe 52-2, And transmits it to the pressure-height converter.

The pressure-height converter converts the measured pressure difference? P into a height difference? H according to the following equation (1).

[Equation 1]

×g ×ΔH? P =

× g × ΔH

은 액체의 밀도이고, g는 중력가속도이다. here,

Is the density of the liquid, and g is the gravitational acceleration.

Vessel (V) may be a sealed pressure vessel.

The temperature of the low temperature liquefied gas may be lower than the atmospheric temperature (for example, 0 DEG C or lower). For example, the low temperature liquefied gas may be liquefied nitrogen at -196 ° C.

Hereinafter, a method of designing each component of the apparatus 50 will be described in detail.

1) Design of liquid inlet (h _L ) and gas outlet (h _V )

5, the pressure on the liquid side of the gas discharge hole h _V is denoted by P + H ₁ , the pressure on the liquid side of the liquid inlet hole h _L is denoted by P + H ₂ , If in (51) if a internal pressure P + H _m or a liquid level fluctuation, or the liquid level fluctuation rate is the design _{range, P + H 1 ≤ P +} H m ≤ P + the relationship of H ₂ is satisfied, and, Hm Appears as the measured liquid level.

The flow rate of the liquid flowing through the liquid inlet port h _L is equal to the flow rate of the gas discharged through the gas outlet port h _{v in the} steady state in which there is no liquid level fluctuation, Since the amount of heat absorbed through the surface is sufficiently large, the liquid evaporates as soon as it is drawn into the evaporator 51 from the container V and the liquid does not rise above the liquid inlet hole h _L inside the evaporator 51 If, on the fluid evaporation tube 51 flows in, and the evaporated gas is required going back into the container (V) through the gas discharging hole (h _V), the driving force (driving force, F _d) is equation (2) assumes followed by a gas discharge hole _(V h) and the liquid suction hole (h _L) difference (D _g -D _l) between the between the height difference (ΔH), and the density of the liquid (D _l) and the density of the gas (D _g) .

&Quot; (2) "

F _d = C x H x (D ₁ - D _g )

Where C is a unit conversion constant and C is 1.0 x 10 ^-4 when the unit of F _d is kg / cm ² , the unit of ΔH is m, and the unit of D is kg / m ³ .

The liquid flown from the vessel V to the evaporation vessel 51 through the liquid inlet hole h _L in a steady state is evaporated and then the mass flow rate discharged to the vessel V through the gas discharge hole h _V mass flow rate, M) is determined at the equilibrium point where the driving force (F _d ) and the pressure loss due to the fluid flow (ΔP _flow ) are equal.

The pressure loss due to the fluid flow (ΔP _flow ) occurs almost as liquid and gas pass through the liquid inlet port (h _L ) and the gas outlet port (h _V ), respectively, so that the liquid and gas flow into the liquid inlet h _L ) and the gas discharge hole (h _V ) is represented by? P ₁ and? P _g ,

F _d =? P _flow =? P ₁ +? P _g

ΔP ₁ = C × K ₁ × D ₁ × V ₁ ² ,

ΔP _g = C × K _g × D _g × V _g ²

Here, K _l and K _g are the pressure loss coefficients of the liquid inlet port (h _L ) and the gas outlet port (h _V ), and the values of the correct pressure loss coefficients, K _l and K _g , can be obtained through experiments.

D _l and D _g are the liquid density and the gas density, respectively,

V _l and V _g are the liquid passing-through velocity (h _L ) passing velocity and the gas venting hole (h _V ) passing velocity,

C is a unit conversion constant, C is 5.1 x 10 ^-6 when the unit of? P is kg / cm ² , the unit of D is kg / m ³ , and the unit of V is m / sec.

2) Design of evaporator 51

The evaporator 51 must have a surface area sufficient to absorb external heat and to evaporate the liquid introduced into the evaporator 51 from the container V through the liquid inlet hole h _L. If the surface area of the evaporator 51 is not sufficiently large, heating means such as a heat-absorbing fin, a thermal head, or a heating element for heating may be provided outside the evaporator 51 to supply necessary evaporation heat. However, since the liquid flow rate to be evaporated in the evaporator 51 is a small amount of about 0.1 to 1.0 kg / hr, it is not necessary to provide a heating means in most cases.

 3) Embodiment

- liquid inlet flow rate through liquid inlet (h _L ): 0.1 to 1.0 kg / h

- Diameter of liquid inlet (h _L ) and gas outlet (h _V ): 3 to 5 mm

- Difference in height (ΔH) between the liquid inlet port (h _L ) and the gas outlet port (h _V ): 20 to 40 mm

- Diameter of the nozzle (i.e., diameter of the evaporator 51): 2 to 3 inches

- Size of evaporator (51): 2 ~ 3 inch pipe × 100 ~ 150 mm length

Hereinafter, the operation principle of the liquid level measuring apparatus 50 for cryogenic liquefied gas will be described in detail with reference to FIG.

First, the sealed vessel (V) is filled with low-temperature liquefied gas (S10).

Next, the low-temperature liquefied gas is phase equilibrated in the vessel (V) by the liquid phase (L _P ) and the vapor phase (V _P ) (S20).

Subsequently, the liquid in the liquid phase portion L _P is drawn into the evaporator 51 through the liquid inlet hole h _L and evaporated in the evaporator 51, and then part of the liquid in the evaporator 51 and the first pressure filling the inner space of the signal transmission tube 52-1, and the other is returned to the container (V) through the gas discharging hole (h _V) (S30). As the process S30 is repeated, the internal pressure of the evaporator 51 and the first pressure signal transfer pipe 52-1 becomes equal to the total pressure of the low temperature liquefied gas filled in the container V.

Simultaneously with the above-described process (S30), a part of the gas of the gas phase portion V _P flows into the second pressure signal transfer pipe 52-2 (S40).

Thereafter, the differential pressure liquid level sensor 53 measures the pressure difference between the gas pressure P1 filled in the first pressure signal transfer pipe 52-1 and the gas pressure P2 filled in the second pressure signal transfer pipe 52-2 The pressure difference AP is measured to calculate the liquid level I of the low temperature liquefied gas filled in the vessel V. [

The liquid level measuring apparatus 50 for low temperature liquefied gas having the above configuration continuously flows the liquid from the vessel V into the apparatus 50 at a constant flow rate into the apparatus 50, A liquid inlet port h _L and a gas discharge port h _V are formed so as to be able to return to the inside of the evaporator 51. The purge gas is self- And can be referred to as a precise self-purge type pressure detection device.

6 is a schematic view of an apparatus for measuring liquid level of a low temperature liquefied gas 60 according to a first embodiment of the present invention and a pressure vessel V for a low temperature liquefied gas equipped with the apparatus.

6 includes a pair of nozzles 61-1 and 61-2, a pair of shutoff valves 62-1 and 62-2, an evaporator 63, a pair of pressure Signal conduits 64-1 and 64-2, and a differential pressure level 65.

Referring to FIG. 6, the vessel V is filled with a low-temperature liquefied gas, and the low-temperature liquefied gas is composed of a liquid phase portion L _P and a vapor phase portion V _P which is phase-balanced with the liquid phase portion L _P. The interface (I) between the liquid portion (L _P ) and the vapor portion (V _P ) is referred to as a liquid level. The outer wall of the container V is surrounded by a heat insulating material IM to block heat input and output and to reduce the cold and heat loss of the container V. [

The container V has a single wall and a pair of holes (that is, a hole communicating with the gas passage (R _V ) and a hole into which the evaporator 63 is inserted) are formed on one side of the single wall, The gas liquid level measuring device 60 is configured to communicate with the container V through the pair of holes formed in the single wall of the container V. [

The evaporator 63 is inserted into the nozzle 61-1 and the nozzle 61-2 includes the gas passage R _V.

The pair of shutoff valves 62-1 and 62-2 is always open when the factory in which the vessel V is installed and is closed only during maintenance of the vessel V and / Thereby preventing the low-temperature liquefied gas from flowing out of the vessel (V).

The liquid inlet port h _L and the gas outlet port h _v are formed in the evaporation cylinder 63.

The liquid inlet port h _L and the gas outlet port h _V communicate with the container V and the evaporator 63, respectively.

The operation principle of the low temperature liquefied gas liquid level measuring apparatus 60 is the same as the operation principle of the low temperature liquefied gas liquid level measuring apparatus 50, so a detailed description thereof will be omitted here.

7 is a schematic view of an apparatus for measuring liquid level of a low temperature liquefied gas 70 according to a second embodiment of the present invention and a pressure vessel V for a low temperature liquefied gas equipped with the apparatus 70. Fig. Flow control plate 74 provided in the gas-liquid level measuring device 70. As shown in FIG.

7 includes a pair of nozzles 71-1 and 71-2, a pair of shutoff valves 72-1 and 72-2, a liquid inlet pipe 73, a magnetic purge A flow control plate 74, an evaporator 75, a pair of pressure signal transmission lines 76-1 and 76-2, and a differential pressure liquid level meter 77. [

Referring to FIG. 7, the vessel V is filled with a low temperature liquefied gas, and the low temperature liquefied gas is composed of a liquid phase portion L _P and a vapor phase portion V _P which is in phase with the liquid phase portion L _P. The interface (I) between the liquid portion (L _P ) and the vapor portion (V _P ) is referred to as a liquid level. The outer wall of the container V is surrounded by a heat insulating material IM to block heat input and output and to reduce the cold and heat loss of the container V. [

The container V has a single wall, and a pair of holes (that is, a hole communicating with the gas passage R _V and a hole into which the evaporator 75 is inserted) are formed on one side of the single wall, The gas liquid level measuring device 70 is configured to communicate with the container V through the pair of holes formed in the single wall of the container V. [

An evaporator 75 is inserted into the nozzle 71-1 and the nozzle 71-2 includes a gas passage R _V.

The pair of shutoff valves 72-1 and 72-2 is always open when the factory in which the vessel V is installed and is only closed during maintenance of the vessel V and / Thereby preventing the low-temperature liquefied gas from flowing out of the vessel (V).

The liquid inlet pipe (73) communicates with the evaporator (75). This liquid inlet pipe 73 may be in the form of a hollow cylinder.

A magnetic purge flow rate regulating plate 74 is disposed between and coupled to the liquid inlet pipe 73 and the evaporator 75. For example, the magnetic purge flow rate regulating plate 74 may be coupled to the liquid inlet pipe 73 and the evaporator 75 by a flange union, respectively.

Referring to Fig. 9, the magnetic purge flow rate regulating plate 74 includes a holding portion HD, a liquid inlet hole h _L , and a gas outlet hole h _v .

The holding portion HD refers to the handle of the operator.

The liquid inlet port h _L and the gas outlet port h _V communicate with the liquid inlet pipe 73 and the evaporator 75.

The liquid level measuring apparatus 70 for low temperature liquefied gas can easily change the diameters of the liquid inlet holes h _L and h _v and the height difference therebetween during operation (that is, the self purge flow rate regulating plate 74) It is possible to easily adjust the liquid level change detection speed and the cold loss amount by replacing the liquid level change speed with another one.

The operation principle of the low temperature liquefied gas liquid level measuring apparatus 70 is the same as that of the low temperature liquefied gas liquid level measuring apparatus 50, and therefore, a detailed description thereof will be omitted here.

8 is a schematic view of an apparatus 80 for measuring liquid level of a low temperature liquefied gas according to a third embodiment of the present invention and a pressure vessel V for a low temperature liquefied gas equipped with the apparatus 80. Fig. Is a detailed view of the self-purge flow rate regulating plate 83 provided in the gas liquid level measuring apparatus 80.

8 is provided with a pair of nozzles 81-1 and 81-2, a pair of shutoff valves 82-1 and 82-2, a magnetic purge flow rate control plate 83, A barrel 84, a pair of pressure signal transmission pipes 85-1 and 85-2, and a differential pressure level meter 86.

Referring to FIG. 8, the vessel V is filled with a low temperature liquefied gas, and the low temperature liquefied gas is composed of a liquid phase portion L _P and a vapor phase portion V _P which is in phase with the liquid phase portion L _P. The interface (I) between the liquid portion (L _P ) and the vapor portion (V _P ) is referred to as a liquid level. The outer wall of the container V is surrounded by a heat insulating material IM to block heat input and output and to reduce the cold and heat loss of the container V. [

The container V has a single wall and a pair of holes (that is, holes communicating with the gas passage (R _V ) and the liquid passage (R _L ) respectively) are formed on one side of the single wall, (80) is configured to communicate with the container through the pair of holes formed in the single wall of the container (V).

The nozzle 81-1 includes a liquid passage R _L , and the nozzle 81-2 includes a gas passage R _V.

The pair of shutoff valves 82-1 and 82-2 is always open when the factory in which the container V is installed and is only closed during the maintenance of the container V and / Thereby preventing the low-temperature liquefied gas from flowing out of the vessel (V).

The self purge flow rate regulating plate 83 is disposed between the nozzle 81-1 and the evaporator 84 and coupled thereto. For example, the self purge flow rate regulating plate 83 may be coupled to the nozzle 81-1 and the evaporator 84 by flange unions, respectively.

9, the magnetic purge flow rate regulating plate 83 includes a holding portion HD, a liquid inlet hole h _L , and a gas outlet hole h _v .

The holding portion HD refers to the handle of the operator.

The liquid inlet port h _L and the gas outlet port h _V communicate with the liquid path R _L in the nozzle 81-1 and the evaporation tube 84.

The liquid level measuring device 80 for low temperature liquefied gas can easily change the diameters of the liquid inlet holes h _L and h _v and the height difference therebetween during the operation It is possible to easily adjust the liquid level change detection speed and the cold loss amount by replacing the liquid level change speed with another one.

The operation principle of the low temperature liquefied gas liquid level measuring device 80 is the same as that of the low temperature liquefied gas liquid level measuring device 50, and therefore, detailed description thereof will be omitted here.

10 is a schematic view of an apparatus 90 for measuring liquid level of a low temperature liquefied gas according to a fourth embodiment of the present invention and a pressure vessel (V) for a low temperature liquefied gas equipped with the apparatus.

10 includes an evaporation cylinder 91, a pair of pressure signal transmission pipes 92-1 and 92-2 and a differential pressure level meter 93. The liquid level measurement apparatus 90 of FIG.

Referring to FIG. 10, the vessel V is filled with a low-temperature liquefied gas, and the low-temperature liquefied gas is composed of a liquid phase portion L _P and a vapor phase portion V _P which is in phase with the liquid phase portion L _P. The interface (I) between the liquid portion (L _P ) and the vapor portion (V _P ) is referred to as a liquid level.

The container V has a double wall including an inner wall Vi and an outer wall Vo and the inner wall Vi and the outer wall Vo each have at least one hole (for example, a part of the evaporator 91) A hole of the inner wall Vi and a hole of an outer wall Vo through which the pressure signal transmission pipe 92-1 penetrates and at least a part of the low temperature liquefied gas liquid level measuring device 90 91, a portion of the pressure signal transfer tube 92-1 and the heating means 94) are disposed between the inner wall Vi and the outer wall Vo. That is, the low-temperature liquefied gas liquid level measuring device 90 is configured such that at least a portion thereof is mounted to the container V through the respective holes.

The liquid inlet port h _L and the gas outlet port h _v are formed in the evaporator 91.

The liquid inlet port h _L and the gas outlet port h _V communicate with the container V and the evaporator 91, respectively.

In the liquid level measuring apparatus 90 for low temperature liquefied gas, since the evaporator 91 is disposed between the inner wall Vi and the outer wall Vo, it is not easy to heat the evaporator 91 using the atmospheric heat , And the heating means 94 is used to heat the evaporator 91. That is, the heating means 94 heats and vaporizes the liquid introduced into the evaporator 91 from the vessel V through the liquid inlet hole h _L.

The heating means 94 may comprise a heat-absorbing fin, a thermocouple, a heating coil or a combination thereof.

The operation principle of the low temperature liquefied gas liquid level measuring device 90 is the same as that of the low temperature liquefied gas liquid level measuring device 50, and a detailed description thereof will be omitted here.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the scope of protection of the present invention should be determined by the appended claims.

50, 60, 70, 80, 90: liquid level measuring device
51, 63, 75, 84, 91: Evaporation column
52-1, 52-2, 64-1, 64-2, 76-1, 76-2, 85-1, 85-2, 92-1, 92-2:
53, 65, 77, 86, 93: differential pressure liquid level meter
61-1, 61-2, 71-1, 71-2, 81-1, 81-2: nozzle
62-1, 62-2, 72-1, 72-2, 82-1, 82-2:
73: liquid inlet pipe 74, 83: magnetic purge flow rate control plate
94: Full tropical h _L : Liquid inlet
h _V : gas discharge hole V: container
L _P : liquid phase portion V _P : vapor phase portion
I: Interface or liquid level IM: Insulation
R _L : liquid passage R _V : gas passage
HD: Holding part

Claims (19)

delete delete delete delete delete delete delete A liquid level measuring apparatus for low temperature liquefied gas, which is configured to be installed in a container filled with low temperature liquefied gas,
A liquid inlet configured to pass liquid when installed in the vessel but not to allow gas to pass;
A gas discharge hole configured to pass the gas but not to allow the liquid to pass therethrough when installed in the vessel;
An evaporation cylinder communicating with the liquid inlet and the gas outlet, respectively;
A first pressure signal transmission pipe configured to communicate with the evaporation passage;
A second pressure signal transmission pipe configured to communicate with a vapor phase portion in the vessel to be filled in the vessel when installed in the vessel;
Wherein the first pressure signal transmission line is connected to the first pressure signal transmission line and the other end is connected to the second pressure signal transmission line,
The differential pressure liquid level is measured by measuring a pressure difference? P between a pressure P1 transmitted through the first pressure signal transmitting tube and a pressure P2 transmitted through the second pressure signal transmitting tube, Temperature liquefied gas, wherein the low-
And a second shut-off valve for opening and closing the first nozzle, and a second shut-off valve for opening and closing the second nozzle, wherein the first shut-off valve opens and closes the first nozzle, the second nozzle communicates with the second pressure signal transfer pipe, ,
Further comprising a magnetic purge flow rate adjusting plate disposed between the first nozzle and the evaporator, wherein both the liquid inlet hole and the gas outlet hole are formed in the magnetic purge flow rate adjusting plate. A liquid level measuring apparatus for low temperature liquefied gas, which is configured to be installed in a container filled with low temperature liquefied gas,
A liquid inlet configured to pass liquid when installed in the vessel but not to allow gas to pass;
A gas discharge hole configured to pass the gas but not to allow the liquid to pass therethrough when installed in the vessel;
An evaporation cylinder communicating with the liquid inlet and the gas outlet, respectively;
A first pressure signal transmission pipe configured to communicate with the evaporation passage;
A second pressure signal transmission pipe configured to communicate with a vapor phase portion in the vessel to be filled in the vessel when installed in the vessel;
Wherein the first pressure signal transmission line is connected to the first pressure signal transmission line and the other end is connected to the second pressure signal transmission line,
The differential pressure liquid level is measured by measuring a pressure difference? P between a pressure P1 transmitted through the first pressure signal transmitting tube and a pressure P2 transmitted through the second pressure signal transmitting tube, Temperature liquefied gas, wherein the low-
And a second shut-off valve for opening and closing the first nozzle, and a second shut-off valve for opening and closing the second nozzle, wherein the first shut-off valve opens and closes the first nozzle, the second nozzle communicates with the second pressure signal transfer pipe, ,
And a magnetic purge flow rate adjusting plate disposed between the liquid inlet pipe and the evaporator, wherein the liquid inlet hole and the gas outlet hole are both formed in the magnetic purge flow rate adjusting plate Apparatus for measuring liquid level of low temperature liquefied gas. 10. The method according to claim 8 or 9,
Wherein the liquid inlet hole is located lower than the gas discharge hole. 10. The method according to claim 8 or 9,
Wherein the evaporator is configured to evaporate the introduced low-temperature liquefied gas when the low-temperature liquefied gas flows into the evaporator. 10. The method of claim 9,
Wherein the evaporator is closely inserted into the first nozzle. 10. The method according to claim 8 or 9,
Wherein the liquid inlet hole and the gas outlet hole are both formed in the evaporator. 10. The method according to claim 8 or 9,
And a heating means for heating the evaporator. A pressure vessel for a low-temperature liquefied gas equipped with an apparatus for measuring liquid level of a low temperature liquefied gas according to claim 8 or 9. 16. The method of claim 15,
Wherein the pressure vessel for low-temperature liquefied gas has a single wall, and a pair of holes are formed at one side of the single wall, wherein the low-temperature liquefied gas liquid- A pressure vessel for a low temperature liquefied gas configured to communicate with the vessel through a pair of holes. 16. The method of claim 15,
Wherein the pressure vessel for low-temperature liquefied gas has a double wall including an inner wall and an outer wall, the inner wall and the outer wall each including at least one hole, and at least a part of the liquid- Wherein the low-temperature liquefied gas liquid level measuring device is configured such that at least a portion of the low-temperature liquefied gas passes through the respective holes and is mounted in the pressure vessel for low temperature liquefied gas. 16. The method of claim 15,
The pressure vessel for low-temperature liquefied gas is a pressure vessel. 16. The method of claim 15,
Wherein the temperature of the low-temperature liquefied gas is 0 DEG C or lower.

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