Research Device for High-Efficiency Foam Generation and Hazard Prevention and Control of Liquefied Natural Gas

Abstract

The research device for high-expansion foam generation and its prevention and control of the hazards of liquefied natural gas according to the present invention includes an electric control box, a frame, a position adjustment device, an air entrainment device, a foam liquid spraying device, and a foam liquid loading and testing device. The position adjustment device is installed on the frame, and the air entrainment device is provided on the position adjustment device. The foam liquid spraying device is connected to the air entrainment device, and the end of the air entrainment device is provided with the foam liquid loading and testing device. The air entrainment device and the foam liquid spraying device are respectively connected to the electric control box, and the electric control box is connected to a computer. The beneficial effects of the present invention are as follows: 1. It realizes the diversification of parameter regulation and the simplification of operation of the high-expansion foam generator, with a high degree of parameter visualization, and numerical calculations can be carried out; 2. The foam loading and collection device has a low cost and a great value realization. While meeting the requirement of loading cryogenic liquids, it can study high-expansion foam and its effect on cryogenic liquids and establish a heat transfer model.

Description

Technical Field

[0001] The present invention relates to the field of fire fighting equipment, and specifically relates to a high-expansion foam generator and a research device for preventing and controlling the hazards of liquefied natural gas. Background Art

[0002] Liquefied natural gas (LNG) is a liquid mixture mainly composed of methane, with low price and clean combustion products. Its boiling point temperature at normal pressure is -162°C. However, as a cryogenic liquid, when LNG leaks, it will undergo intense heat exchange with the surrounding environment and quickly vaporize. Due to the volume expansion of more than 600 times during the vaporization process, even a small amount of leakage will generate a huge vapor cloud, which can form a combustible gas with air, and its explosion limit at room temperature is 5% - 15%. When encountering an ignition source, it will cause fire or even explosion accidents, resulting in casualties and property losses. As a clean energy source, liquefied natural gas is currently widely used throughout the country and even the world. While bringing benefits to humanity, liquefied natural gas also brings some safety challenges. It has been proven that high-expansion foam can effectively reduce the gas hazards during high-expansion foam leakage. In the research on the generation mechanism of high-expansion foam, there have been constructions of similar high-expansion foam generators. The quality of the foam is related to factors such as the flow rate of the foam liquid, wind speed, atomization degree of the foam liquid by the nozzle, and the size of the mesh holes of the sieve. However, the operation parameters and variable control of the high-expansion foam generator are troublesome, and it is not easy to operate and replace components. It is very important to achieve simple variable replacement operation of the foam generator during the experiment. In addition, the properties of high-expansion foam and its effects on cryogenic liquids are very important for scientific research work. During the experiment, nitrogen can be used instead of liquefied natural gas to study the diffusion behavior of cryogenic gases under the influence of high-expansion foam. Summary of the Invention

[0003] In order to make the adjustment of the operation parameters of the foam generator more convenient and rapid, with a higher degree of automation and highly controllable foam quality, the present invention provides a high-expansion foam generator and a research device for preventing and controlling the hazards of liquefied natural gas.

[0004] The high-expansion foam generator and the research device for preventing and controlling the hazards of liquefied natural gas according to the present invention adopt the following technical solution: It includes an electric control box, a frame, a position adjustment device, an air entrainment device, a foam liquid spraying device, and a foam liquid loading and testing device. The position adjustment device is installed on the frame, the air entrainment device is provided on the position adjustment device, the foam liquid spraying device is connected to the air entrainment device, the end of the air entrainment device is provided with the foam liquid loading and testing device, the air entrainment device and the foam liquid spraying device are respectively connected to the electric control box, and the electric control box is connected to a computer.

[0005] Further, the position adjusting device includes a vertical guide rail, a horizontal guide rail, a lifting motor, a lead screw, and a support plate. Vertical guide rails are symmetrically arranged on both sides of the frame. The two horizontal guide rails are respectively slidably connected to the vertical guide rails through sliders. A support plate is connected to the bottoms of the two horizontal guide rails. The lifting motor is located below the support plate, is controlled by an electric control box to work, and drives the support plate to drive the horizontal guide rail to slide up or down through the lead screw.

[0006] Further, spacers are respectively arranged at both ends of each horizontal guide rail.

[0007] Further, the air entrainment device includes a foaming cylinder, a nozzle, a screen, and a baffle. A blower, a nozzle, and a screen are sequentially arranged in the foaming cylinder from the head end to the tail end. The baffle is movably arranged at the open end of the tail end of the foaming cylinder. The foaming cylinder is slidably connected to the position adjusting device through a carriage. A wind speed sensor is arranged on the side wall of the foaming cylinder. The blower and the wind speed sensor are respectively connected to the electric control box.

[0008] Further, the foaming cylinder includes cylinder I, cylinder II, cylinder III, and cylinder IV. The 4 cylinders are arranged in sequence from left to right. Adjacent two cylinders are connected by a steel ring and fixed by bolts. The blower, the nozzle, and the screen are respectively located in cylinder I, cylinder III, and cylinder IV. The bottom of each steel ring is respectively connected to the position adjusting device through a carriage.

[0009] Further, the nozzle is fixed in cylinder III through an adjustable collar, and the nozzle is connected to the foam spraying device through a hose.

[0010] Further, the foam liquid spraying device includes a liquid storage tank, a metering pump, a flow meter, a pressure regulating valve, a return pipe, and a pressure gauge. The outlet end of the liquid storage tank is connected to the end port of the air entrainment device through the return pipe. The metering pump is connected to the steel ring through an infusion pipeline. The pressure regulating valve, the flow meter, and the pressure gauge are sequentially arranged on the infusion pipeline. The metering pump and the flow meter are respectively connected to the electric control box. The liquid storage tank is connected to the electric control box through a wire, and a cut-off valve is arranged on the wire.

[0011] Further, the foam liquid loading and testing device includes a foam loading box, a camera, a thermocouple, and a platform scale. The foam loading box is arranged on the platform scale. A plurality of thermocouples are arranged in the foam loading box, and a camera is arranged outside the foam loading box.

[0012] Further, the foam loading box includes a loading cylinder and a stainless steel loading tray at its bottom. A scale is arranged on the side wall of the loading cylinder. A nitrogen sensor is arranged at the upper end of the loading cylinder, and a liquid discharge port is arranged at the bottom of the loading cylinder.

[0013] Further, the stainless - steel holding tray includes a chassis, a heating plate, and a foam board arranged in sequence from top to bottom. The bottom of the chassis is a hollow structure with an air interlayer. A groove with an upward opening is provided on the chassis, and the bottom end of the holding cylinder is clamped in the groove and sealed by sodium chloride liquid.

[0014] The beneficial effects of the present invention are as follows: 1. It realizes the diversification of parameter regulation and the simplification of operation of the high - magnification foam generator, with a high degree of parameter visualization, and numerical calculations can be carried out; 2. The foam holding and collecting device has a low cost and great value realization. While meeting the requirement of holding low - temperature liquids, it can study high - magnification foam and its effect on low - temperature liquids and establish a heat transfer model. Brief Description of the Drawings

[0015] In order to make the content of the present invention more clearly understood, the following further details the present invention according to specific embodiments in conjunction with the drawings.

[0016] Figure 1 It is the front - view structural schematic diagram of the present invention.

[0017] Figure 2 It is the structural schematic diagram of the adjustable ferrule.

[0018] Figure 3 It is the sectional structural schematic diagram of the foam holding box.

[0019] Wherein: 1 - electric control box, 2 - frame, 3 - position adjustment device, 31 - vertical guide, 32 - horizontal guide rail, 33 - lifting motor, 34 - lead screw, 35 - support plate, 36 - spacer block, 4 - air entrainment device, 41 - foaming cylinder, 411 - cylinder Ⅰ, 412 - cylinder Ⅱ, 413 - cylinder Ⅲ, 414 - cylinder Ⅳ, 42 - nozzle, 43 - screen, 44 - baffle, 45 - fan, 46 - steel ring, 461 - through hole, 47 - wind speed sensor, 48 - carriage, 5 - foam liquid spraying device, 51 - liquid storage tank, 52 - metering pump, 53 - flow meter, 54 - pressure regulating valve, 55 - return pipe, 56 - pressure gauge, 57 - liquid delivery pipeline, 58 - stop valve, 6 - foam liquid holding and testing device, 61 - foam holding box, 611 - holding cylinder, 612 - stainless - steel holding tray, 6121 - chassis, 6122 - heating plate, 6123 - foam board, 6124 - air interlayer, 6125 - groove, 613 - scale, 614 - drain port, 62 - camera, 63 - thermocouple, 64 - platform scale, 65 - thermocouple, 66 - nitrogen sensor, 7 - computer, 8 - adjustable ferrule, 81 - fixing bracket, 82 - hose, 83 - ferrule, 84 - adjusting knob. Detailed Embodiment

[0020] As Figure 1As shown, the research device for high-expansion foam generation and its prevention and control of hazards to liquefied natural gas includes an electric control box 1, a frame 2, a position adjustment device 3, an air entrainment device 4, a foam liquid spraying device 5 and a foam liquid holding test device 6. The position adjustment device is installed on the frame 2, the position adjustment device 3 is provided with an air entrainment device 4, the foam liquid spraying device 5 is connected to the air entrainment device 4, and the end of the air entrainment device 4 is provided with a foam liquid holding test device 6. The air entrainment device 4 and the foam liquid spraying device 5 are respectively connected to the electric control box 1, and the electric control box 1 is connected to the computer 7.

[0021] The position adjustment device 3 includes a vertical guide rail 31, a horizontal guide rail 32, a lifting motor 33, a screw rod 34 and a support plate 35. The vertical guide rails 31 are symmetrically provided on the front and rear sides of the frame 1. The two horizontal guide rails 32 are slidably connected to the vertical guide rails 31 through sliders. A spacer 36 is provided at both ends of each horizontal guide rail 32. The bottom of the two horizontal guide rails 32 is connected to the support plate 35. The lifting motor 33 is fixed on the frame and is located below the support plate 35 and is connected to the electric control box through a wire. The driving end of the lifting motor 33 drives the support plate through the screw rod 34 to drive the horizontal guide rail 35 to slide up or down.

[0022] The air entrainment device 4 includes a foaming tube 41, a nozzle 42, a screen 43, a baffle 44, and a fan 45. The foaming tube 41 is made of transparent acrylic material and includes tube I 411, tube II 412, tube III 413, and tube IV 414 arranged in sequence from left to right. Two adjacent tubes are connected by a steel ring 46 and fixed by bolts. A gasket is provided between the foaming tube 41 and the steel ring 46; the fan 45, nozzle 42 and screen 43 are respectively located in tube I 411, tube III 412, and tube IV 413, and a baffle 44 is movably provided at the end of tube IV 413; the bottom of each steel ring 46 is connected to the horizontal guide rail 32 through a slide 48, and a wind speed sensor 47 is provided on the side wall of tube II 412. The fan 45 and the wind speed sensor 47 are respectively connected to the electric control box 1.

[0023] The baffle can be of various structures, and its main purpose is to adjust the opening position so that the foam can fall into the mobile phone device to the maximum extent. The baffle structure designed in this application is U-shaped, with folded edge protection on both sides, so that the foam can fall into the collection device completely.

[0024] Among them, such as Figure 2As shown, the nozzle 42 is installed in the cylinder III through an adjustable ferrule 8. In this embodiment, the adjustable ferrule 8 includes a fixing frame 81, a hose 82, a ferrule 83, and an adjusting knob 84. The fixing frame 81 is fixed in the cylinder III, and the ferrule 83 is fixedly provided on the fixing frame 81. The adjusting knob 84 is provided on the side wall of the ferrule 83. The nozzle is clamped in the ferrule 83 and can move along the length direction of the cylinder III. The position of the nozzle in the cylinder III is fixed by loosening or tightening the adjusting knob 84. A through hole 461 for accommodating the hose is provided on the steel ring, and the nozzle is connected to the foam liquid spraying device through the hose 82.

[0025] In the present invention, in order to more conveniently replace the screen and nozzle components and facilitate the maintenance of the interior of the transparent foaming cylinder, the horizontally placed transparent foaming cylinder is divided into three sections and clamped by steel rings and fixed with screws, and gaskets are provided between the foaming cylinder and the steel rings. The steel rings are connected to the horizontal guide rails. When replacing the components, loosen the steel ring screws so that the transparent cylinder can slide along the horizontal guide rails. After the screen and nozzle are replaced, slide the steel rings and the transparent cylinder to clamp and tighten the screws; in addition, the entire transparent cylinder and the fan can move horizontally to adjust the foam output position. The horizontal foaming cylinder part of the foam generator can achieve height adjustment. The fan, the foaming cylinder, and the horizontal guide rails are integrally mounted on the vertical guide rails, and the lifting motor and the support plate can achieve electric control to adjust the height of the foaming cylinder; a hose connection is adopted between the foaming cylinder and the nozzle, and the nozzle is fixed in the center of the foaming cylinder by an adjustable ferrule device with adjustable tightness. Loosening the ferrule can move the nozzle back and forth and fix it at different positions, thereby adjusting the distance between the nozzle and the screen; the baffle at the end of the foaming cylinder can adjust the opening angle of the baffle through the cooperation of pulleys and steel wires. A wind speed sensor is installed inside the foaming cylinder to detect the magnitude of the wind speed.

[0026] The foam liquid spraying device 5 includes a liquid storage tank 51, a metering pump 52, a flow meter 53, a pressure regulating valve 54, a return pipe 55, and a pressure gauge 56. A return hole is provided at the end of the cylinder IV 414. The outlet end of the liquid storage tank 51 is connected to the return hole through a return pipe 57. The part of the liquid sprayed by the nozzle that does not form foam after passing through the screen can flow into the liquid storage tank through the return pipe; the metering pump 52 is connected to the hose 82 through an infusion pipeline 57. The pressure regulating valve 54, the flow meter 53, and the pressure gauge 56 are sequentially arranged on the infusion pipeline. The metering pump 52 and the flow meter 53 are respectively connected to the electric control box 1. The liquid storage tank is connected to the metering pump through a pipeline, and a stop valve 58 is installed on the pipeline.

[0027] A foam liquid holding and testing device 6 is placed at the end of the foaming cylinder. The foam liquid holding and testing device 6 includes a foam holding box 61, a camera 62, a thermocouple 63, and a platform scale 64. The foam holding box 61 is placed on the platform scale 64, and the camera 62 is arranged outside the foam holding box. The camera can calculate the filling time and breaking time of the foam, and the platform scale can calculate the mass of the foam. It can be used to observe the properties of high-expansion foam and the gas diffusion behavior when high-expansion foam acts on cryogenic liquids, record experimental phenomena, and detect indicators such as temperature and oxygen content.

[0028] The foam holding box 61 includes a holding cylinder 611 and a stainless-steel mounting plate 612 at its bottom. The holding cylinder 611 is made of transparent acrylic material, and a scale 613 for calculating the volume of the foam is provided on its side wall. A nitrogen sensor 66 is provided at the top of the holding cylinder, which can detect the nitrogen concentration at the top of the foam holding box at different time periods. A liquid discharge port 614 is provided at the bottom of the holding cylinder. Three vertical rods are provided inside the holding cylinder 611, and a plurality of pairs of thermocouples 65 are arranged along the length direction of each vertical rod to realize longitudinal and transverse temperature measurement inside the holding cylinder 611, and further obtain the evaporation law of the cryogenic liquid.

[0029] The stainless-steel mounting plate 612 includes a chassis 6121, a heating plate 6122, and a foam board 6123 arranged from top to bottom. The bottom of the chassis 6121 is a hollow structure containing an air interlayer 6124. A groove 6125 with an upward opening is provided on the chassis. To prevent cryogenic liquid and evaporation gas from leaking from the surroundings, a stainless-steel mounting plate is used to hold the cryogenic liquid. The bottom of the transparent acrylic holding cylinder is clamped in the groove 6125 and sealed with a sodium chloride solution. A heating plate is installed under the chassis, and the temperature of the heating plate can be adjusted to indirectly control the evaporation rate of the cryogenic liquid in the mounting plate. The heating plate, in combination with the polyvinyl chloride foam board, can also prevent the mounting plate from being damaged by excessive cold due to too low temperature, which may damage the platform scale.

[0030] Experimental method:

[0031] 1. High-expansion foam testing and characterization

[0032] Adjust different foam liquid ratios, foam liquid flow rates, sieve mesh sizes, wind speeds, and droplet atomization degrees to generate high-expansion foam. Use the foam holding and testing device to collect high-expansion foam. By measuring the foam mass (m foam ) and drainage mass (m drain ) with the platform scale, measuring the volume of the foam enclosure (V foam ), the time (t) for the enclosure to be filled with foam, and continuously recording the height (h) of the foam layer with the video, determine the generation rate Foaming multiple Bubble size (R), breakage rate

[0033] 2. Mitigation of Gas Hazards Caused by High-Expansion Foam Acting on LNG

[0034] Connect both the thermocouple and the nitrogen sensor to the data acquisition device. Turn on the camera and the computer. Inject liquid nitrogen instead of LNG into the cryogenic liquid containment device, and then add high-expansion foam.

[0035] The camera records the fragmentation rate of the high-expansion foam during the gas hazard prevention and control process. The thermocouple measures the temperature distribution curve of the foam layer to reveal the heat transfer mechanism of the high-expansion foam blocking heat convection and thermal radiation. The large-scale balance measures the vaporization rate of the liquid nitrogen, and the thermocouple measures the temperature curve of the foam layer to observe and measure the structural characteristics of the foam layer, revealing the heat transfer mechanism of the high-expansion foam vaporizing the cryogenic liquid. Measure the temperature curve of the vaporized gas in the foam layer, observe and measure the size, quantity, and distribution of the gas channels in the foam layer, revealing the heat transfer mechanism of the high-expansion foam heating and vaporizing the gas.

[0036] The above is only the preferred solution of the present invention and is not intended as a further limitation of the present invention. All equivalent changes made by using the content of the specification and drawings of the present invention are within the protection scope of the present invention.

Claims

1. Research device for high-expansion foam generation and its prevention and control of hazards to liquefied natural gas, characterized in that, It includes an electric control box, a frame, a position adjustment device, an air entrainment device, a foam liquid spraying device, and a foam liquid loading and testing device. The position adjustment device is installed on the frame. An air entrainment device is provided on the position adjustment device. The foam liquid spraying device is connected to the air entrainment device. A foam liquid loading and testing device is provided at the end of the air entrainment device. The air entrainment device and the foam liquid spraying device are respectively connected to the electric control box, and the electric control box is connected to a computer; The position adjustment device includes a vertical guide rail, a horizontal guide rail, a lifting motor, a lead screw, and a support plate. Vertical guide rails are symmetrically provided on both sides of the frame. Two horizontal guide rails are respectively slidably connected to the vertical guide rails through sliders. A support plate is connected to the bottoms of the two horizontal guide rails. The lifting motor is located below the support plate and is controlled by the electric control box to work and drives the support plate to drive the horizontal guide rail to slide up or down through the lead screw; The air entrainment device includes a foaming cylinder, a nozzle, a screen, and a baffle. A blower, a nozzle, and a screen are sequentially provided in the foaming cylinder from the head end to the tail end. The baffle is movably provided at the open end of the tail end of the foaming cylinder. The foaming cylinder is slidably connected to the position adjustment device through a carriage. An air velocity sensor is provided on the side wall of the foaming cylinder. The blower and the air velocity sensor are respectively connected to the electric control box.

2. The high - magnification foam generation and its research device for preventing and controlling the hazards of liquefied natural gas according to claim 1, characterized in that, Partition blocks are respectively provided at both ends of each horizontal guide rail.

3. The high-power foam generation and its research device for preventing and controlling the hazards of liquefied natural gas according to claim 1, wherein The foaming cylinder includes cylinder Ⅰ, cylinder Ⅱ, cylinder Ⅲ, and cylinder Ⅳ. The 4 cylinders are arranged in sequence from left to right. Adjacent two cylinders are connected by a steel ring and fixed by bolts. The blower, the nozzle, and the screen are respectively located in cylinder Ⅰ, cylinder Ⅲ, and cylinder Ⅳ. The bottom of each steel ring is respectively connected to the position adjustment device through the carriage.

4. The high - magnification foam generation and its research device for preventing and controlling the hazards of liquefied natural gas according to claim 3, characterized in that, The nozzle is fixed in cylinder Ⅲ through an adjustable ferrule, and the nozzle is connected to the foam spraying device through a hose.

5. The high-foam generation and its research device for preventing and controlling the hazards of liquefied natural gas according to claim 1, characterized in that The foam liquid spraying device includes a liquid storage tank, a metering pump, a flow meter, a pressure regulating valve, a return pipe, and a pressure gauge. The outlet end of the liquid storage tank is connected to the end port of the air entrainment device through the return pipe. The metering pump is connected to the air entrainment device through an infusion pipeline. A pressure regulating valve, a flow meter, and a pressure gauge are sequentially arranged on the infusion pipeline. The metering pump and the flow meter are respectively connected to the electric control box. The liquid storage tank is connected to the metering pump through a pipeline, and a stop valve is installed on the pipeline.

6. The high-power foam generation and its research device for preventing and controlling the hazards of liquefied natural gas according to claim 1, characterized in that The foam liquid loading and testing device includes a foam storage box, a camera, a thermocouple, and a platform scale. The foam storage box is provided on the platform scale. A plurality of pairs of thermocouples are provided in the foam storage box, and a camera is provided outside the foam storage box.

7. The high-power foam generation and its research device for preventing and controlling the hazards of liquefied natural gas according to claim 6, characterized in that, The foam storage box includes a storage cylinder and a stainless steel storage tray at its bottom. A scale is provided on the side wall of the storage cylinder. A nitrogen sensor is provided at the top of the storage cylinder, and a liquid discharge port is provided at the bottom of the storage cylinder.

8. The high magnification foam generation and its research device for preventing and controlling the hazards of liquefied natural gas according to claim 7, characterized in that, The stainless steel storage tray includes a chassis, a heating plate, and a foam plate arranged in sequence from top to bottom. The bottom of the chassis is a hollow structure containing an air interlayer. A groove with an upward opening is provided on the chassis. The bottom end of the storage cylinder is clamped in the groove and sealed by sodium chloride liquid.

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