CN116118992A - A Ventilation System for the Empty Space of Type B LNG Fuel Tanks - Google Patents

Abstract

The invention discloses a ventilation system for the empty space of a B-type LNG fuel tank, which includes a gas leakage detector and a pressure sensor. In the formed empty space, the outer bulkhead is penetrated and sealed connected with an exhaust pipeline connecting the inside and outside of the outer bulkhead, and an airtight electric switch is installed on the exhaust pipeline to switch the passage between the empty space and the outside atmosphere. The side where the butterfly valve and airtight electric butterfly valve are connected to the outside atmosphere is provided with an explosion-proof exhaust fan, and the explosion-proof exhaust fan, airtight electric butterfly valve, gas leakage detector and pressure sensor are respectively electrically connected to the PLC control module. The ventilation system provided by the invention is compact in structure, easy to install, and has its own PLC control module, which can automatically adjust according to the gas detection and pressure sensing of the empty space, the explosion-proof exhaust fan and the airtight electric butterfly valve to meet the different states of the empty space The following ventilation requirements.

Description

A Ventilation System for the Empty Space of Type B LNG Fuel Tanks

technical field

The invention relates to a B-type LNG fuel tank (B-type tank is a structural type of fuel tank, mainly including three types of A/B/C; LNG fuel tank refers to a tank loaded with LNG fuel, and the Chinese meaning of LNG is The ventilation system for liquefied natural gas) empty spaces belongs to the field of shipbuilding.

Background technique

As the governments of various countries and the International Maritime Organization continue to increase the emission requirements of CO ₂ , NO _X and SO _X , more and more ships are beginning to use more economical and environmentally friendly gaseous fuels. There is an empty space between the insulation structure and the outer bulkhead of the B-type LNG tank of a dual-fuel ship, and a maintenance platform will be set in the empty space for daily personnel to enter and maintain; while the ship is sailing, the empty space will Fill inert gas to remove air and water vapor, keep the empty space dry and a certain pressure environment; when the LNG fuel tank leaks or is in an accident state, there will be dangerous gas in the empty space, when the amount of dangerous gas When the concentration reaches a certain level, when the maintenance personnel maintain it, it will endanger the health and even life of the personnel. At this time, it is necessary to provide emergency ventilation to remove the dangerous gas as soon as possible.

The current published patent CN113443116A discloses a ventilation method for a liquefied gas carrier and an empty cargo tank thereof, which provides ventilation for an empty cargo tank.

The document "Zhou Zhixian, Yang Lingkang, Wu Hairong. Discussion on the Design of LNG Dual-fuel Powered Ships. Naval Engineering, 2014 (4)" published in the China Academic Literature Network Publishing General Database, this paper is aimed at the design points of dual-fuel engine ships , the key technologies of dual-fuel ship design, such as the arrangement of LNG fuel tanks, the selection of storage tanks, the way of fuel filling, the design of double-wall pipe ventilation system and the exhaust system with special requirements, are analyzed. The text refers to the ventilation system for the engine room and double wall ducts.

The document "Zhao Meng, Guo Dongxue. Analysis of the key points of the gas hazard zone division of dual-fuel ro-ro passenger ships. Basic Science and Technology, 2020 (11)" published in the China Academic Literature Network Publishing General Database, this paper is aimed at the hazard zone of dual-fuel ships Division, analysis of the definition of dangerous areas, the division of dangerous areas in fuel tank spaces, the division of dangerous areas in ventilation inlet and outlet, and the division of hazards in related spaces of C-type tanks, etc. The article focuses on the division of hazardous areas. As for ventilation, it only mentions that "LNG-related hazardous areas should be continuously ventilated, and the inlet and outlet of ventilation pipes should be high enough to avoid the installation of closing devices required by the Load Line Convention.".

Contents of the invention

The technical problem to be solved in the present invention is: how to design a kind of ventilation system applicable to the empty space of the B-type LNG fuel tank under the normal working state/accident state/personnel maintenance state, which can meet the ventilation requirements in various states and ensure Environmental and personnel safety in vacant spaces.

In order to solve the above-mentioned technical problems, the technical solution of the present invention is to provide a ventilation system for the empty space of the B-type LNG fuel tank, which is characterized in that it includes a gas leak detector and a pressure sensor, and both the gas leak detector and the pressure sensor are set In the void space formed between the LNG fuel tank and the outer bulkhead, the outer bulkhead is penetrating and sealed with an exhaust pipeline connecting the inside and outside of the outer bulkhead. The gas-tight electric butterfly valve that switches the passage between the empty space and the outside atmosphere, the side where the air-tight electric butterfly valve is connected to the outside atmosphere is equipped with an explosion-proof exhaust fan, the explosion-proof exhaust fan, the air-tight electric butterfly valve, the gas leakage detector and the pressure sensor respectively It is electrically connected with the PLC control module; the gas leak detector and pressure sensor feed back the signal to the PLC control module in real time, and the PLC control module judges whether to open or close the airtight electric butterfly valve and explosion-proof exhaust valve according to the signal fed back by the gas leak detector and pressure sensor fan.

Preferably, when the gas leakage detector detects that the concentration of the gas to be detected exceeds the set value, it will alarm and open the airtight electric butterfly valve and open the explosion-proof exhaust fan through the PLC control module; when the pressure measured by the pressure sensor is lower than a When the set value is set, alarm and open the airtight electric butterfly valve and explosion-proof exhaust fan through the PLC control module; when the pressure measured by the pressure sensor is higher than another set value, alarm and open the airtight electric butterfly valve and open the Explosion-proof exhaust fan; when the signals fed back by the gas leakage detector and pressure sensor are at the normal set value, the airtight electric butterfly valve and the explosion-proof exhaust fan are closed through the PLC control module.

Preferably, the exhaust pipeline includes at least one airtight exhaust pipe, one end of each airtight exhaust pipe is arranged in the void space, and the other end of each airtight exhaust pipe passes through the outer bulkhead and It is sealed and connected to the outer bulkhead, and the discharge end of each airtight exhaust pipe is provided with an airtight electric butterfly valve and an explosion-proof exhaust fan for exhausting the empty space.

Preferably, the exhaust pipeline also includes a plurality of exhaust grilles, and each airtight exhaust pipe is evenly distributed with a plurality of exhaust grilles; each airtight exhaust pipe passes through a plurality of exhaust grilles. The grid is connected to the empty space.

Preferably, both the airtight electric butterfly valve and the explosion-proof exhaust fan are arranged outside the outer bulkhead.

Preferably, the airtight electric butterfly valve is interlocked with the explosion-proof exhaust fan.

Preferably, the airtight electric butterfly valve is in an airtight and normally closed state, and is opened or closed by the PLC control module according to the signals of the gas leakage detector and the pressure sensor, and when opened, the air in the empty space is discharged to the outside atmosphere , to ensure the airtight state of the void space when closed, and to withstand the filling pressure of the inert gas in the airtight state.

Preferably, one side of the outer bulkhead is provided with a manhole cover; the manhole cover is a passage for personnel to enter the empty space for maintenance, and is also used as a ventilation inlet.

Preferably, the outlet end of the explosion-proof exhaust fan is provided with a ventilator.

Preferably, the explosion-proof exhaust fan, airtight electric butterfly valve, airtight exhaust pipe, exhaust grille, gas leakage detector, and pressure sensor are all explosion-proof, non-sparking, and low-temperature-resistant structures.

The temperature of the empty space of the B-type LNG fuel tank is low under normal working conditions, and the interior is filled with inert gas, which requires a certain pressure bearing and sealing performance; in an emergency state, emergency ventilation is required to reduce the risk of dangerous gases in the space. Concentration; when the personnel are in the maintenance state, the personnel need to enter, and the inert gas in the space needs to be removed to provide a good and safe environment. Therefore, the design of the ventilation system of the present invention needs to take into account the requirements of each state, not only to ensure good pressure bearing and air tightness under normal working conditions, but also to quickly and effectively discharge dangerous gases under emergency conditions. Under the state, the inert gas can be quickly and effectively discharged to ensure the safety of the environment and personnel.

Compared with prior art, the beneficial effect of the present invention is:

1) The ventilation system of the present invention is composed of a ventilator, an explosion-proof exhaust fan, an airtight electric butterfly valve, an airtight duct, an exhaust grille, a gas leakage detector, a pressure sensor, a PLC control module and a manhole cover, and the pipeline is connected Easy to install. According to the gas concentration and pressure changes in the vacant space, the working status of the ventilation system can be automatically controlled to meet the ventilation requirements in different states of the vacant space and ensure the safety of the environment and personnel in the vacant space.

2) The entire ventilation system of the present invention adopts PLC control, automatic adjustment, simple operation, and can be operated according to different state requirements of the empty space.

3) The ventilation system provided by the present invention is an independent system, which is suitable for the structure of the B-type LNG fuel tank with a small space in the vacant space. Gas does not leak under pressure.

The ventilation system provided by the invention is compact in structure, easy to install, and has its own PLC control module, which can automatically adjust according to the gas detection and pressure sensing of the empty space, the explosion-proof exhaust fan and the airtight electric butterfly valve to meet the different states of the empty space The following ventilation requirements shall be met to ensure the safety of the environment and personnel in the empty space.

Description of drawings

Fig. 1 is a schematic diagram of the principle of a ventilation system for a B-type LNG fuel tank empty space;

Figure 2 is a schematic diagram of the connection of the airtight exhaust pipe.

Detailed ways

In order to make the present invention more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

The present invention provides a ventilation system for a B-type LNG fuel tank empty space, as shown in Figure 1, which includes a ventilator 1, an explosion-proof exhaust fan 2, an airtight electric butterfly valve 3, an airtight exhaust pipe 4, an exhaust The grille 5, the gas leakage detector 6, the pressure sensor 7, the manhole cover 8, the PLC control module 9, and the ventilator 1 are arranged at the air outlet end of the explosion-proof exhaust fan 2, and are used to provide a passage for the explosion-proof exhaust fan 2 to exhaust air; The gas leakage detector 6 and the pressure sensor 7 are all arranged in the empty space 12 formed between the LNG fuel tank 10 and the outer bulkhead 11, and the outer bulkhead 11 is penetrated and sealed to connect with the outer tank The exhaust pipeline on the inside and outside of the wall 11 is equipped with an airtight electric butterfly valve 3 that switches the passage between the empty space 12 and the outside atmosphere, and the side of the airtight electric butterfly valve 3 that is connected to the outside atmosphere is provided with an explosion-proof exhaust. Fan 2, airtight electric butterfly valve 3 and explosion-proof exhaust fan 2 are interlocked, airtight electric butterfly valve 3, gas leakage detector 6 and pressure sensor 7 are electrically connected to PLC control module 9 respectively; gas leakage detector 6 and pressure sensor 7 real-time The signal is fed back to the PLC control module 9, and the PLC control module 9 judges whether to open or close the airtight electric butterfly valve 3 and the explosion-proof exhaust fan 2 according to the signals fed back by the gas leakage detector 6 and the pressure sensor 7.

The exhaust pipeline includes an airtight exhaust pipe 4 and an exhaust grille 5 at the end for exhaust. The exhaust medium is dangerous gas or inert gas. In this embodiment, one end of the airtight exhaust pipe 4 is arranged in the empty space 12, and the other end of the airtight exhaust pipe 4 passes through the outer bulkhead 11 and is sealed and connected to the outer bulkhead 11. The airtight electric butterfly valve 3 and the explosion-proof exhaust fan 2 are all arranged on the outside of the outer bulkhead 11. A plurality of exhaust grilles 5 are evenly distributed on the airtight exhaust pipe 4; the airtight exhaust pipe 4 is connected to the empty space 12 through the plurality of exhaust grilles 5.

An airtight electric butterfly valve 3 is arranged at the discharge end of the airtight exhaust pipe 4 to ensure the airtightness of the empty space 12 and is interlocked with the explosion-proof exhaust fan 2 . An explosion-proof exhaust fan 2 is arranged at the discharge end of the airtight exhaust pipe 4 to exhaust the empty space 12 .

The explosion-proof exhaust fan 2 is interlocked with the airtight electric butterfly valve 3, starts or stops according to the open or closed state of the airtight electric butterfly valve 3, and discharges the gas in the empty space 12 to the outside atmosphere when starting;

The airtight electric butterfly valve 3 is in an airtight and normally closed state, interlocked with the explosion-proof exhaust fan 2, and is controlled by the PLC control module 9 according to the signals of the gas leakage detector 6 and the pressure sensor 7. The air in 12 is discharged to the outside atmosphere, and the airtight state of the void space 12 is guaranteed when closed, and can withstand the filling pressure of the inert gas in the airtight state;

Airtight exhaust pipe 4: used to discharge air from the empty space 12, and ensure airtightness under a certain pressure in the cabin;

Exhaust grille 5: exhaust terminal equipment;

Gas leak detector 6: used to detect the concentration of dangerous gas in the empty space 12 (the gas leak detector 6 is specifically a gas concentration sensor, and the dangerous gas is mainly methane, which is the main component of liquefied natural gas), and feeds back the signal to the PLC control module 9. When the concentration exceeds the set value, an alarm (in this embodiment, an audible and visual alarm can be performed by outputting an alarm signal) and the airtight electric butterfly valve 3 and the explosion-proof exhaust fan 2 are opened through the PLC control module 9;

Pressure sensor 7: used to feed back the pressure of the empty space 12, when the pressure is lower than a set value, the signal is fed back to the PLC control module 9, an alarm is issued and the airtight electric butterfly valve 3 and the explosion-proof exhaust fan 2 are opened through the PLC control module 9 When the pressure is higher than another set value, the signal is fed back to the PLC control module 9, and the alarm (in this embodiment, the sound and light alarm can be carried out by outputting the alarm signal) and the airtight electric butterfly valve 3 and the airtight electric butterfly valve 3 are opened by the PLC control module 9 Turn on the explosion-proof exhaust fan 2;

Manhole cover 8: personnel maintenance access, and also used for ventilation inlet. When the manhole cover 8 is opened, the empty space 12 is in a state of depressurization, and the pressure sensor 7 acts to alarm and open the airtight electric butterfly valve through the PLC control module 9 3 and turn on the explosion-proof exhaust fan 2 to discharge the inert gas in the empty space 12 before the personnel enter, so as to ensure the safety of personnel entering.

PLC control module 9: According to the signal fed back by the pressure sensor 7, determine what state it is in, and correspondingly open/close the airtight electric butterfly valve 3, and open/stop the explosion-proof exhaust fan 2.

When the signal fed back by the pressure sensor 7 is within the normal setting value or range (some pressure sensors can set the pressure range, and some pressure sensors can only set the pressure value), it means that the pressure in the premises is stable and in a normal working state. At this time, the ventilation system is in the air. When the pressure of the pressure sensor 7 is higher than the set value and the gas leakage detector 6 alarms, the LNG fuel tank 10 may have gas leakage and is in an accident state, and the ventilation system is turned on for emergency exhaust; when personnel enter , the manhole cover 8 is opened, and the space loses pressure. At this time, the pressure of the pressure sensor 7 is lower than the set value, and the ventilation system is opened for exhaust.

Explosion-proof exhaust fan 2, airtight electric butterfly valve 3, airtight exhaust pipe 4, exhaust grille 5, gas leakage detector 6, pressure sensor 7, all need to be explosion-proof and non-sparking, and low temperature resistant.

The connection point of the airtight exhaust pipe 4 (here the connection point is the connection point connecting the outer bulkhead and the inner exhaust pipe, which needs to be airtight here, and the exhaust pipe in the cabin does not need to be airtight, mainly The airtight integrity needs to be ensured through the external airtight bulkhead.) Silicone resin mixture glue is used at the place, and the rubber tape is wrapped outside, as shown in Figure 2.

The working principle of the present invention is as follows:

The empty space 12 is in a positive pressure state filled with inert gas during the normal working state of the ship, and the ventilation system is kept closed and airtight; when the empty space 12 is in an accident state, there is leakage of LNG dangerous gas, and the ventilation system is turned on at this time. Quickly discharge the leaked dangerous gas; when the vacant space 12 is under maintenance, the personnel need to open the manhole cover 8 to enter. At this time, it is in a state of depressurization, and the ventilation system is opened to discharge the inert gas in the vacant space 12. Quickly return to the outside atmosphere to allow safe entry for personnel.

When the PLC control module 9 opens the airtight electric butterfly valve 3 and the explosion-proof exhaust fan 2 for a period of time, and the signals fed back by the gas leakage detector 6 and the pressure sensor 7 are all within the normal set value, the gas is automatically closed by the PLC control module 9 . Close electric butterfly valve 3 and explosion-proof exhaust fan 2.

The ventilation system of the present invention is applicable to the empty space of the B-type LNG fuel tank in the normal working state/accident state/personnel maintenance state, and can meet the ventilation requirements in various states.

The ventilation system of the present invention can ensure the complete airtightness under a certain pressure after the empty space 12 of the B-type LNG fuel tank 10 is filled with inert gas under normal working conditions; when the LNG fuel tank 10 leaks, it is in an accident state According to the feedback signal from the gas leakage detector 6 and the pressure sensor 7 to the PLC control module 9, the airtight electric butterfly valve 3 is automatically opened, the explosion-proof exhaust fan 2 is started for effective ventilation, and the dangerous gas is quickly discharged to reduce the dangerous gas in the empty space 12 concentration to ensure the environmental safety requirements of the vacant space 12 of the LNG fuel tank 10; in the state of personnel maintenance, the manhole cover 8 is opened, and at this time, there is no pressure in the vacant space 12, and the pressure sensor 7 feeds back a signal to the PLC control module 9, Automatically open the airtight electric butterfly valve 3, start the explosion-proof exhaust fan 2 for effective ventilation, quickly discharge the inert gas in the space, provide safe and effective ventilation before personnel enter, and provide a good and safe environment. The switching of various states should be able to be automatically controlled.

Claims (10)

1. The ventilation system of the B-type LNG fuel cabin space is characterized by comprising a gas leakage detector (6) and a pressure sensor (7), wherein the gas leakage detector (6) and the pressure sensor (7) are arranged in a space (12) formed between an LNG fuel cabin (10) and an outer bulkhead (11), an exhaust pipeline communicated with the inner side and the outer side of the outer bulkhead (11) is penetrated and connected on the outer bulkhead (11) in a sealing manner, an airtight electric butterfly valve (3) for switching a passage between the space (12) and the outside atmosphere is arranged on the exhaust pipeline, an explosion-proof exhaust fan (2) is arranged on one side, connected with the outside atmosphere, of the airtight electric butterfly valve (3), and the gas leakage detector (6) and the pressure sensor (7) are respectively and electrically connected with a PLC control module (9); the gas leakage detector (6) and the pressure sensor (7) feed signals back to the PLC control module (9) in real time, and the PLC control module (9) judges whether to open or close the airtight electric butterfly valve (3) and the explosion-proof exhaust fan (2) according to the signals fed back by the gas leakage detector (6) and the pressure sensor (7).

2. A ventilation system for a reserved place of a type B LNG fuel tank according to claim 1, characterized in that when the gas leakage detector (6) detects that the concentration of the gas to be detected exceeds a set value, an alarm is given and a PLC control module (9) opens an airtight electric butterfly valve (3) and an explosion-proof exhaust fan (2); when the pressure measured by the pressure sensor (7) is lower than a set value, alarming and opening the airtight electric butterfly valve (3) and the explosion-proof exhaust fan (2) through the PLC control module (9); when the pressure measured by the pressure sensor (7) is higher than another set value, alarming and opening the airtight electric butterfly valve (3) and opening the explosion-proof exhaust fan (2) through the PLC control module (9); when signals fed back by the gas leakage detector (6) and the pressure sensor (7) are both at normal set values, the airtight electric butterfly valve (3) is closed and the explosion-proof exhaust fan (2) is closed through the PLC control module (9).

3. A ventilation system for a B-type LNG fuel tank space according to claim 1, wherein the exhaust pipeline comprises at least one airtight exhaust pipe (4), one end of each airtight exhaust pipe (4) is arranged in the space (12), the other end of each airtight exhaust pipe (4) passes through the outer bulkhead (11) and is connected to the outer bulkhead (11) in a sealing manner, and the exhaust end of each airtight exhaust pipe (4) is provided with an airtight electric disc valve (3) and an explosion-proof exhaust fan (2) for exhausting air from the space (12).

4. A ventilation system for a reserved place of a type B LNG fuel tank according to claim 3, wherein the exhaust pipeline further comprises a plurality of exhaust gratings (5), and each airtight exhaust pipe (4) is uniformly provided with a plurality of exhaust gratings (5); each airtight exhaust pipe (4) is communicated with the air-reserving place (12) through a plurality of exhaust grids (5).

5. A ventilation system for a B-type LNG fuel tank space according to claim 1 or 3, characterized in that the airtight electric butterfly valve (3) and the explosion-proof exhaust fan (2) are both arranged outside the outer bulkhead (11).

6. A ventilation system for a reserved place of a type B LNG fuel tank according to claim 1, wherein the airtight electric butterfly valve (3) is interlocked with the explosion-proof exhaust fan (2).

7. A ventilation system of a B-type LNG fuel tank space according to claim 1, wherein the airtight electric butterfly valve (3) is in airtight normally closed state, and is controlled to be opened or closed by the PLC control module (9) according to signals of the gas leakage detector (6) and the pressure sensor (7), and the air of the space (12) is discharged to the outside atmosphere when opened, and the airtight state of the space (12) is ensured when closed, and the ventilation system can bear the filling pressure of inert gas in the airtight state.

8. A ventilation system for a B-type LNG fuel tank space according to claim 1, wherein a manhole cover (8) is provided on one side of the outer tank wall (11); the manhole cover (8) is a passage for personnel to repair and enter the space (12) and is also used as a ventilation inlet.

9. The ventilation system of the blank space of the type-B LNG fuel tank of claim 1, wherein the air outlet end of the explosion-proof exhaust fan (2) is provided with a ventilator (1).

10. The ventilation system of the blank space of the type-B LNG fuel tank as claimed in claim 1, wherein the explosion-proof exhaust fan (2), the airtight electric butterfly valve (3), the airtight exhaust pipe (4), the exhaust grid (5), the gas leakage detector (6) and the pressure sensor (7) are of explosion-proof and spark-free structures and can resist low temperature.

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