Marine LNG storage tank high liquid level alarm system

Abstract

The utility model discloses a marine LNG storage tank high liquid level alarm system which is characterized in that a vent pipe is arranged on an LNG storage tank and comprises a high-position alarm overflow pipe and a high-position alarm overflow pipe, one end of the high-position alarm overflow pipe and one end of the high-position alarm overflow pipe are communicated with the LNG storage tank through cabin penetrating pieces, and the other end of the high-position alarm overflow pipe and the other end of the high-position alarm overflow pipe are communicated with the vent pipe; a high-position alarm temperature sensor and a high-position alarm overflow pipe remote control valve are arranged on the high-position alarm overflow pipe, and the high-position alarm overflow pipe remote control valve is located on the side, away from the LNG storage tank, of the high-position alarm temperature sensor; a high and high level alarm temperature sensor, a high and high level alarm overflow pipe remote control valve and a cut-off piece are arranged on the high and high level alarm overflow pipe, the high and high level alarm overflow pipe remote control valve is located between the high and high level alarm temperature sensor and the cut-off piece, and the high and high level alarm temperature sensor is located on the side, close to the LNG storage tank, of the high and high level alarm overflow pipe remote control valve. The alarm system provided by the utility model eliminates the situation of false alarm of high-position alarm and high-position alarm.

Description

Technical Field

[0001] The utility model relates to the technical field of ship fuel equipment, in particular to a high liquid level alarm system for a ship LNG storage tank. Background Art

[0002] LNG is an ultra-low temperature liquid. For ships that use LNG as a power fuel, LNG is stored in separate tanks. According to regulatory requirements, these LNG storage tanks must be equipped with high-level alarms and high-high-level alarms to prevent the high-level alarm from failing or malfunctioning. The high-high-level alarm can also serve as an alarm to prevent overpressure in the LNG storage tank, which would cause great risks.

[0003] At present, there are several alarm methods on the market: radar measurement, pressure conduction, and overflow temperature measurement. Each measurement method has its own advantages and disadvantages, but only the third overflow temperature measurement method is that after the LNG liquid level reaches the overflow pipe, the temperature sensor directly measures the temperature change in the overflow pipe, thereby reflecting the height of the liquid level in the LNG storage tank, and the error value is relatively small. However, no matter what measurement method is used, there is still a certain probability of false alarms. How to effectively reduce the probability of false alarms is the content of our technical research, especially for the alarm system using overflow temperature measurement. Since there may be LNG reliquefied by BOG in the overflow pipe, the temperature measurement is abnormal, which leads to false alarms. Therefore, how to ensure accurate measurement of liquid level height and liquid level alarm is the core point of our technology. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a high liquid level alarm system for a marine LNG storage tank. When the liquid level reaches the high level alarm, it will not have any impact on the high-high level alarm, thereby eliminating the false alarm of the high-high level alarm.

[0005] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A high liquid level alarm system for a marine LNG storage tank, wherein one or two vent pipes are provided on the LNG storage tank, including a high-level alarm overflow pipe and a high-high-level alarm overflow pipe, one end of the high-level alarm overflow pipe and the high-high-level alarm overflow pipe are both connected to the LNG storage tank through a tank penetration piece, and the other end is connected to a vent pipe; a high-level alarm temperature sensor and a high-level alarm overflow pipe remote control valve are provided on the high-level alarm overflow pipe, and the high-level alarm overflow pipe remote control valve is located on a side of the high-level alarm temperature sensor away from the LNG storage tank; a high-high-level alarm temperature sensor, a high-high-level alarm overflow pipe remote control valve and a shut-off piece are provided on the high-high-level alarm overflow pipe, the high-high-level alarm overflow pipe remote control valve is located between the high-high-level alarm temperature sensor and the shut-off piece, and the high-high-level alarm temperature sensor is located on a side of the high-high-level alarm overflow pipe remote control valve close to the LNG storage tank.

[0007] Furthermore, the shut-off member is one of a throttling orifice plate and a check valve.

[0008] Furthermore, a vent pipe remote control valve is provided on the vent pipe, and the vent pipe remote control valve is located on a side of the connection point between the high-high-level alarm overflow pipe and the vent pipe close to the LNG storage tank.

[0009] Furthermore, the pressure difference between the two sides of the throttling orifice plate is 1 / 2 of the tank pressure of the LNG storage tank.

[0010] Furthermore, the number of the ventilation pipes is 1, the high-high-level alarm overflow pipe and one end of the high-level alarm overflow pipe are both connected to the ventilation pipe, and the connection point between the high-level alarm overflow pipe and the ventilation pipe is higher than the connection point of the high-high-level alarm ventilation pipe.

[0011] Furthermore, the high-level alarm overflow pipe remote control valve and the high-high-level alarm overflow pipe remote control valve are both fault-closing type remote control valves.

[0012] The utility model discloses a marine LNG storage tank high liquid level alarm system, wherein an overflow pipe is led out at the high level alarm and high-high level alarm positions of the LNG storage tank respectively, and a temperature sensor is installed on the overflow pipe respectively; when the liquid level reaches the overflow pipe position, LNG will enter the overflow pipe, and the temperature sensor on the overflow pipe will detect the temperature change at this time; when the temperature reaches the set value, the temperature sensor will send out an alarm signal, and this alarm signal represents that the liquid level has reached this position; in addition, a fault-closing remote control valve is installed on each overflow pipe, and this valve is normally closed at ordinary times, and can be automatically closed when the valve itself fails, so as to prevent LNG from leaking to the external area.

[0013] In order to ensure the accuracy of the measurement, the overflow pipe must maintain a closed circulation system, so no matter whether it is a high-level alarm or a high-high-level alarm, the end of the overflow pipe is connected to the vent pipe of the LNG storage tank to ensure that the overflowed LNG liquid can return to the LNG storage tank.

[0014] In order to prevent LNG liquid in the high-level overflow pipe from reversely entering the overflow pipeline of the high-high-level alarm through the vent pipe, thereby causing a false alarm of the high-high-level liquid level, a shut-off piece is added to the high-high-level alarm overflow pipe.

[0015] Compared with traditional alarm methods, the high liquid level alarm system for marine LNG storage tanks of the utility model realizes accurate measurement and alarm of liquid level only through two overflow pipes, temperature sensors and remote control valves. This design scheme has been recognized by classification societies, fully meets the requirements of specifications, and can optimize the design of LNG storage tanks and reduce the risk of LNG storage tank leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the high liquid level alarm system for a marine LNG storage tank according to Example 1 of the utility model;

[0017] Figure 2 It is a structural schematic diagram of the high liquid level alarm system for marine LNG storage tanks described in Example 2 of the present utility model.

[0018] Among them, 1-LNG storage tank, 2-high-level alarm overflow pipe, 3-high-level alarm temperature sensor, 4-high-level alarm overflow pipe remote control valve, 5-high-high-level alarm overflow pipe, 6-high-high-level alarm temperature sensor, 7-high-high-level alarm overflow pipe remote control valve, 8-vent pipe, 9-check valve, 10-throttling orifice plate, 11-vent pipe remote control valve. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. Example

[0020] like Figure 1As shown, a marine LNG storage tank high liquid level alarm system, wherein a vent pipe 8 is provided on the LNG storage tank 1, including a high-level alarm overflow pipe 2 and a high-high-level alarm overflow pipe 5, one end of the high-level alarm overflow pipe 2 and the high-high-level alarm overflow pipe 3 are both connected to the LNG storage tank 1 through a tank penetration, and the other end is connected to the vent pipe 8, and the connection point between the high-level alarm overflow pipe 2 and the vent pipe 8 is higher than the connection point between the high-high-level alarm overflow pipe 5 and the vent pipe 8; a high-level alarm temperature sensor 3 and a high-level alarm overflow pipe remote control valve 4 are provided on the high-level alarm overflow pipe 2, and the high-level alarm overflow pipe remote control valve 4 is located on the side of the high-level alarm temperature sensor 3 away from the LNG storage tank 1; the high-level alarm overflow pipe 5 is provided with a high-level alarm temperature sensor 6, a high-level alarm overflow pipe remote control valve 7 and a check valve 9, the high-level alarm overflow pipe remote control valve 7 is located between the high-level alarm temperature sensor 6 and the check valve 9, and the high-level alarm temperature sensor 3 is located on the side of the high-level alarm overflow pipe remote control valve 7 close to the LNG storage tank 1; the vent pipe 8 is provided with a vent pipe remote control 11, and the vent pipe remote control valve 11 is located on the side of the connection point between the high-level alarm overflow pipe 5 and the vent pipe 8 close to the LNG storage tank 1. Example

[0021] like Figure 2 As shown, the shutoff component in the high liquid level alarm system of the marine LNG storage tank 1 of this embodiment is a throttling orifice plate 10, and the other parts of the structure are the same as those of Example 1; the pressure difference on both sides of the throttling orifice plate 10 is 1 / 2 of the tank pressure of the LNG storage tank.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high liquid level alarm system for a marine LNG storage tank, wherein one or two vent pipes are provided on the LNG storage tank, characterized in that: It comprises a high-level alarm overflow pipe and a high-high-level alarm overflow pipe, one end of each of the high-level alarm overflow pipe and the high-high-level alarm overflow pipe are connected with the LNG storage tank through a cabin penetration component, and the other end of each of the high-level alarm overflow pipe is connected with a vent pipe; a high-level alarm temperature sensor and a high-level alarm overflow pipe remote control valve are provided on the high-level alarm overflow pipe, and the high-level alarm overflow pipe remote control valve is located on the side of the high-level alarm temperature sensor away from the LNG storage tank; a high-high-level alarm overflow pipe is provided with a high-high-level alarm temperature sensor, a high-high-level alarm overflow pipe remote control valve and a shut-off component, the high-high-level alarm overflow pipe remote control valve is located between the high-high-level alarm temperature sensor and the shut-off component, and the high-high-level alarm temperature sensor is located on the side of the high-high-level alarm overflow pipe remote control valve close to the LNG storage tank.

2. A marine LNG storage tank high liquid level alarm system according to claim 1, characterized in that: The shut-off member is one of a throttling orifice plate and a check valve.

3. A marine LNG storage tank high liquid level alarm system according to claim 2, characterized in that: A vent pipe remote control valve is provided on the vent pipe, and the vent pipe remote control valve is located on a side of the connection point between the high-high-level alarm overflow pipe and the vent pipe close to the LNG storage tank.

4. A marine LNG storage tank high liquid level alarm system according to claim 2, characterized in that: The pressure difference on both sides of the throttling orifice plate is 1 / 2 of the tank pressure of the LNG storage tank.

5. A marine LNG storage tank high liquid level alarm system according to claim 1, characterized in that: The number of the ventilation pipe is 1, the high-high-level alarm overflow pipe and one end of the high-level alarm overflow pipe are both connected to the ventilation pipe, and the connection point between the high-level alarm overflow pipe and the ventilation pipe is higher than the connection point of the high-high-level alarm ventilation pipe.

6. A marine LNG storage tank high liquid level alarm system according to claim 1, characterized in that: The high-level alarm overflow pipe remote control valve and the high-high-level alarm overflow pipe remote control valve are both fault-closing type remote control valves.

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