Non-condensate double-wall pipe liquefied natural gas fuel supply system

Abstract

The present invention discloses a condensate-free double-wall pipe liquefied natural gas gas supply system, which includes a gas heater, a double-wall pipe, an air extraction system between the double-wall pipes, a first temperature sensor and a humidity sensor; a flow regulating valve is provided at the heating medium inlet of the gas heater; a second temperature sensor is provided at the gas outlet of the gas heater; the condensate-free double-wall pipe liquefied natural gas gas supply system further includes a data processing and control module; the first temperature sensor, the second temperature sensor, the humidity sensor and the flow regulating valve are all connected to the data processing and control module. The present invention can prevent the air between the double-wall pipes from generating condensate.

Description

Technical Field

[0001] The present invention relates to the technical field of ships, and particularly to a condensate-free double-wall pipe liquefied natural gas fuel supply system. Background Art

[0002] To meet safety requirements, the pipelines used by liquefied natural gas fuel engines in the engine room are double-wall pipes, that is, there are two inner and outer pipelines on the cross-section of the fuel gas pipeline in the engine room. The liquefied natural gas fuel flowing in the inner pipe is used by the engine. This fuel is heated from a liquid fuel at about -160°C to a gaseous fuel at 0°C to 60°C through a heater. The air flows between the inner and outer pipes. Relevant regulations require mechanical exhaust for the space between the inner and outer walls, with the air change rate not less than 30 times per hour and maintaining negative pressure at all times. At the same time, a hazardous gas detection device is provided at the air outlet to obtain information on the leakage of the fuel gas in the inner pipe in a timely manner.

[0003] In summer, the air flowing between the inner and outer pipes is humid and hot. When it contacts the relatively low-temperature (about 30°C) inner pipe wall, it is easy to condense the water in the air, and over time, it is easy to accumulate liquid at the lower part of the pipeline and may block the normal air circulation between the inner and outer pipes, ultimately resulting in the inability of the gas detection device to monitor whether the fuel gas in the inner pipe leaks.

[0004] The current solution usually adopted is to introduce dry air at the air inlet to reduce the dew point of the air, so that no condensate will be precipitated when the mixed air contacts the relatively low-temperature inner pipe wall. The dry air is obtained by reducing the pressure of the control air at 0.7 MPa.

[0005] The dry air simply mixes with the external air through devices such as pressure reducing valves and orifice plates and then enters the double-wall pipe space. It cannot control the mixing amount of the control air according to the temperature and humidity changes at sea, cannot know whether the dew point temperature of the mixed air is lower than the temperature of the inner pipe, and thus cannot evaluate whether the purpose of preventing condensate generation is achieved. At the same time, it will also increase unnecessary energy consumption. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defects existing in the prior art and provide a condensate-free double-wall pipe liquefied natural gas fuel supply system.

[0007] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0008] A condensate-free double-wall pipe liquefied natural gas fuel supply system, which includes a gas heater for heating the fuel from the fuel tank into a gaseous state, a double-wall pipe for transporting the gas to the fuel engine through a gas valve group unit, and a ventilation system between the double-wall pipes for continuously circulating the air between the double-wall pipes; it also includes a first temperature sensor for detecting the atmospheric temperature and a humidity sensor for detecting the atmospheric humidity; a flow regulating valve for adjusting the flow rate of the heating medium entering the gas heater is provided at the heating medium inlet of the gas heater; a second temperature sensor for detecting the gas temperature is provided at the gas outlet of the gas heater; the condensate-free double-wall pipe liquefied natural gas fuel supply system also includes a data processing and control module for controlling the flow regulating valve based on the calculated atmospheric dew point temperature and the gas temperature detected by the second temperature sensor; the first temperature sensor, the second temperature sensor, the humidity sensor, and the flow regulating valve are all connected to the data processing and control module.

[0009] The data processing and control module is a programmable logic controller that can calculate the atmospheric dew point temperature based on the atmospheric temperature detected by the first temperature sensor and the atmospheric humidity detected by the humidity sensor.

[0010] The condensate-free double-wall pipe liquefied natural gas fuel supply system also includes a gas heating control box; the first temperature sensor, the humidity sensor, and the data processing and control module are all provided inside the gas heating control box.

[0011] The first temperature sensor, the second temperature sensor, the humidity sensor, and the flow regulating valve are all connected to the data processing and control module through signal cables.

[0012] The double-wall pipe includes an inner pipe for transporting the gas and an outer pipe sleeved on the inner pipe, and a channel for air flow is formed between the inner pipe and the outer pipe.

[0013] The ventilation system between the double-wall pipes includes a suction fan for extracting the air between the inner pipe and the outer pipe of the double-wall pipe and discharging it to the atmosphere.

[0014] The air inlet of the ventilation system between the double-wall pipes includes a double-wall pipe air inlet provided on the fuel engine and an air inlet at the end of the double-wall pipe before the gas pipeline enters the engine room.

[0015] The air outlet of the ventilation system between the double-wall pipes is provided on the gas valve group unit.

[0016] The ventilation system between the double-wall pipes also includes a hazardous gas detector provided before the air inlet of the suction fan.

[0017] The material of the double-wall pipe is metal.

[0018] The beneficial effects of the present invention are as follows: In the present invention, by setting up a temperature monitoring and control device, the regulation of the gas temperature is realized. The temperature of the gas in the double-wall pipe is always higher than the atmospheric dew point temperature. Therefore, no condensate is generated on the outer wall of the inner pipe in contact with the atmosphere; there is no need to introduce dry air between the double-wall pipes, and there is no need to worry about the condensate generated by the air entering between the double-wall pipes; the heating temperature of the gas is dynamically adjusted according to the changes in the sea air temperature and humidity under different conditions, and the control of the gas temperature is more scientific. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a preferred embodiment of the present invention.

[0020] Figure 2 is Figure 1 the sectional view taken along line A-A in

[0021] Figure 3 It is a process control diagram of a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The following is a preferred embodiment and is described in more clearly and completely in conjunction with the drawings to illustrate the present invention.

[0023] As Figure 1 and Figure 2 shown, a condensate-free double-wall pipe liquefied natural gas gas supply system includes a gas heater 10 for heating the fuel from the fuel tank 17 into a gaseous state, a double-wall pipe 20 for delivering the gas to the fuel engine 16 through the gas valve group unit 15, and a double-wall pipe interlayer air extraction system for continuously circulating the air between the double-wall pipes.

[0024] The double-wall pipe 20 includes an inner pipe 21 for delivering the gas and an outer pipe 22 sleeved on the inner pipe, and a channel for air flow is formed between the inner pipe and the outer pipe. The material of the double-wall pipe is metal.

[0025] The double-wall pipe interlayer air extraction system includes a suction fan 41 for extracting the air between the inner pipe and the outer pipe of the double-wall pipe and discharging it to the atmosphere, and a hazardous gas detector 45 provided before the air inlet of the suction fan 41.

[0026] The air inlet of the double-wall pipe interlayer air extraction system includes a double-wall pipe air inlet 42 provided on the fuel engine 16 and an air inlet 43 at the end of the double-wall pipe before the gas pipeline enters the engine room 50.

[0027] The air outlet 44 of the double-wall pipe interlayer air extraction system is provided on the gas valve group unit 15.

[0028] The air extraction system between the double-walled pipes enables continuous air circulation between the double-walled pipes. This system is a mechanical air extraction system. The required air change rate is not less than 30 times per hour. The air inlets are in the safe areas, namely the air inlets of the double-walled pipes on the engine and the air inlets at the ends of the double-walled pipes before the gas pipeline enters the engine room. The outlet pipeline of the air extraction system between the double-walled pipes is on the gas valve group unit, which can suck the air from the fuel engine and the ends of the double-walled pipes into the gas valve group unit and then discharge it to the atmosphere through the outlet pipeline and the exhaust fan. A hazardous gas detector is provided before the air enters the exhaust fan. In this way, once the gas pipeline leaks, information can be obtained in the first time.

[0029] The condensate-free double-walled pipe liquefied natural gas gas supply system further includes a first temperature sensor 31 for detecting the atmospheric temperature and a humidity sensor 33 for detecting the atmospheric humidity.

[0030] The gas heater has a heating medium inlet 11 and a heating medium outlet 12. The heating medium of the gas heater enters and exits the gas heater 10 through the medium pipeline 18. Through heat exchange, the heating medium can heat the gas entering the gas heater 10.

[0031] The gas heater 10 has a gas inlet 13 and a gas outlet 14. The gas heated by the gas heater 10 enters the gas buffer tank 51 through the gas pipeline 19 and then enters the engine room 50 from the gas buffer tank.

[0032] A flow regulating valve 34 for regulating the flow rate of the heating medium entering the gas heater is provided at the heating medium inlet 11 of the gas heater 10.

[0033] A second temperature sensor 32 for detecting the gas temperature is provided at the gas outlet 14 of the gas heater 10.

[0034] The condensate-free double-walled pipe liquefied natural gas gas supply system further includes a data processing and control module 35 for controlling the flow regulating valve based on the calculated atmospheric dew point temperature and the gas temperature detected by the second temperature sensor.

[0035] The first temperature sensor 31, the second temperature sensor 32, the humidity sensor 33 and the flow regulating valve 34 are all connected to the data processing and control module 35.

[0036] In this embodiment, the data processing and control module 35 is a programmable logic controller that can calculate the atmospheric dew point temperature according to the atmospheric temperature detected by the first temperature sensor and the atmospheric humidity detected by the humidity sensor.

[0037] The condensate-free double-walled pipe liquefied natural gas gas supply system further includes a gas heating control box 36; the first temperature sensor 31, the humidity sensor 33 and the data processing and control module 35 are all provided in the gas heating control box 36.

[0038] The first temperature sensor 31, the second temperature sensor 32, the humidity sensor 33 and the flow regulating valve 34 are all connected to the data processing and control module 35 through a signal cable 37.

[0039] The working process of the condensate-free double-wall pipe liquefied natural gas fuel supply system of the present invention is as follows: The fuel tank sends liquid liquefied natural gas fuel to the gas heater, and heat exchange is carried out through the heating medium in the gas heater to heat the liquid liquefied natural gas into gaseous fuel that meets the combustion requirements of the fuel engine; the gas enters the gas buffer tank on the deck and then enters the engine room through a pipeline from the gas buffer tank; after entering the engine room, due to safety requirements, all gas pipelines need to adopt double-wall pipes, and the liquefied natural gas flowing in the inner pipe of the double-wall pipe enters the fuel engine for combustion after passing through the gas valve group unit.

[0040] A flow regulating valve is provided at the heating medium inlet of the gas heater, which can accept the valve opening adjustment signal given by the data processing and control module. The first temperature sensor and the humidity sensor can respectively detect the temperature and humidity of the atmosphere in real time. The data processing and control module calculates the atmospheric dew point temperature according to the atmospheric temperature measured by the first temperature sensor and the atmospheric humidity measured by the humidity sensor. This atmospheric dew point temperature serves as the minimum temperature reference value that the gas needs to reach after being heated. A second temperature sensor is provided at the gas outlet of the gas heater, which feeds back the temperature of the gas after heating to the data processing and control module in real time, compares it with the reference temperature value, and then gives a flow adjustment instruction to the flow regulating valve at the heating medium inlet of the gas heater.

[0041] As Figure 3 shown, if the gas temperature at the gas outlet of the gas heater is lower than the atmospheric dew point temperature, the opening of the flow regulating valve at the heating medium inlet of the gas heater is increased to increase the flow rate of the heating medium, so as to increase the heating temperature of the gas in the gas heater and raise the gas temperature at the gas outlet of the gas heater. When the gas temperature at the gas outlet of the gas heater is higher than the atmospheric dew point temperature, there is no need to adjust the flow regulating valve at the heating medium inlet of the gas heater.

[0042] In the present invention, the temperature of the gas in the double-wall pipe is always higher than the atmospheric dew point temperature. Therefore, no condensate is generated on the outer wall of the inner pipe in contact with the atmosphere. There is no need to introduce dry air between the double-wall pipes, and there is no need to worry about condensate being generated by the air entering between the double-wall pipes. The heating temperature of the gas is dynamically adjusted according to the changes in the temperature and humidity of the sea air under different conditions, and the control of the gas temperature is more scientific.

[0043] The condensate-free double-wall pipe liquefied natural gas gas supply system of the present invention is a gas supply system with temperature monitoring and control functions. By setting up a temperature monitoring and control device, the regulation of the gas temperature is realized, and no condensate is generated between the double-wall pipes during the operation of the system.

[0044] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A condensate-free double-wall pipe liquefied natural gas fuel supply system, which includes a gas heater for heating the fuel from the fuel tank into a gaseous state, a double-wall pipe for delivering the gas to the fuel engine through a gas valve group unit, and a ventilation system between the double-wall pipes for continuously circulating the air between the double-wall pipes; characterized in that, It also includes a first temperature sensor for detecting the atmospheric temperature and a humidity sensor for detecting the atmospheric humidity; a flow regulating valve for regulating the flow rate of the heating medium entering the gas heater is provided at the heating medium inlet of the gas heater; a second temperature sensor for detecting the gas temperature is provided at the gas outlet of the gas heater; the condensate-free double-wall pipe liquefied natural gas gas supply system further includes a data processing and control module for controlling the flow regulating valve based on the calculated atmospheric dew point temperature and the gas temperature detected by the second temperature sensor; the first temperature sensor, the second temperature sensor, the humidity sensor and the flow regulating valve are all connected to the data processing and control module; the data processing and control module is a programmable logic controller that can calculate the atmospheric dew point temperature according to the atmospheric temperature detected by the first temperature sensor and the atmospheric humidity detected by the humidity sensor; the first temperature sensor, the second temperature sensor, the humidity sensor and the flow regulating valve are all connected to the data processing and control module through signal cables.

2. The condensate-free double-wall pipe liquefied natural gas fuel supply system according to claim 1, characterized in that, The condensate-free double-wall pipe liquefied natural gas gas supply system further includes a gas heating control box; the first temperature sensor, the humidity sensor and the data processing and control module are all arranged in the gas heating control box.

3. The condensate-free double-walled pipe liquefied natural gas fuel supply system according to claim 1, characterized in that, The double-wall pipe includes an inner pipe for transporting gas and an outer pipe sleeved on the inner pipe, and a channel for air flow is formed between the inner pipe and the outer pipe.

4. The condensate-free double-wall pipe liquefied natural gas fuel supply system according to claim 3, wherein, The air extraction system between the double-wall pipes includes an exhaust fan for extracting the air between the inner pipe and the outer pipe of the double-wall pipe and discharging it into the atmosphere.

5. The condensate-free double-wall pipe liquefied natural gas fuel supply system according to claim 4, characterized in that The air inlet of the air extraction system between the double-wall pipes includes an air inlet of the double-wall pipe provided on the fuel engine and an air inlet at the end of the double-wall pipe before the gas pipeline enters the engine room.

6. The condensate-free double-wall pipe liquefied natural gas gas supply system according to claim 4, characterized in that, The air outlet of the air extraction system between the double-wall pipes is provided on the gas valve group unit.

7. The condensate-free double-walled pipe liquefied natural gas fuel supply system according to claim 4, wherein The air extraction system between the double-wall pipes further includes a hazardous gas detector provided before the air inlet of the exhaust fan.

8. The condensate-free double-wall pipe liquefied natural gas fuel supply system according to claim 3, characterized in that, The material of the double-wall pipe is metal.

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