Natural gas hydrate generating device capable of being quickly disassembled for sampling

[0028] The present invention will be further described below in conjunction with the drawings:

[0029] Such as figure 1 As shown, the natural gas hydrate generation device that can be quickly disassembled and sampled includes a reactor 1, a stirring device 2 and a DBR wind box 3, such as figure 2 , image 3 As shown, the stirring device 2 includes a reversible motor 4 and a fixed base 5. The fixed base 5 is mounted on the motor shaft 8 of the reversible motor 4. The reversible motor 4 is also provided with two limit switches, namely the limit switch A6 And limit switch B7; the reactor 1 is installed on the fixed seat 5, and the stirring device 2 equipped with the reactor 1 is installed in the DBR wind box 3.

[0030] Such as Figure 4 As shown, the reactor 1 includes an upper end cover 9, a lower end cover 10, a fixed assembly 11 and a plexiglass cylinder 12. The upper end cover 9 is installed on the upper end of the plexiglass cylinder 12, and the upper end cover 9 and the plexiglass cylinder 12 An O-shaped sealing ring A13 is provided between the lower end cover 10 and the lower end of the organic glass cylinder 12, and an O-shaped sealing ring B14 is provided between the lower end cover 10 and the organic glass cylinder 12, and the upper end cover 9 and the lower end cover 10 pass through four The root fixing assembly 11 is connected and fixed. The fixing assembly 11 is composed of an upper link 15 and a lower link 16. The upper link 15 and the lower link 16 are connected by a hinge 17, and the end of the upper link 15 is fixed to On the upper end cover 9, such as Image 6 As shown, the lower end cover 10 is provided with a U-shaped through slot 18 that cooperates with the lower connecting rod 16 of the fixing assembly 11. The lower connecting rod 16 passes through the U-shaped through groove 18 of the lower end cover 10 and is installed at the end of the lower connecting rod 16 Fastening butterfly mother fixed; such as Figure 5 , Image 6 As shown, the upper end cover 9 and the lower end cover 10 are respectively provided with an upper end cover pipe fitting hole 19 and a lower end cover pipe fitting hole 20; figure 1 As shown, the reactor 1 is connected to the sample cylinder 21 through the pipe fittings installed in the pipe fitting hole 19 of the upper end cover, and the sample cylinder 21 is also connected to the displacement pump 22. The pipe fitting hole of the lower end cover 10 of the reaction vessel 1 is sealed.

[0031] Such as Figure 5 As shown, the upper end cover 9 is provided with two sensor insertion holes 23, and the two sensor insertion holes 23 are respectively provided with a pressure sensor 24 and a temperature sensor 25.

[0032] Such as Figure 4 As shown, the lower part of the upper end cover 9 is provided with external threads, the upper end of the organic glass cylinder 12 is provided with internal threads, and the upper end cover 9 and the organic glass cylinder 12 are connected by threads.

[0033] At present, the main instruments for generating natural gas hydrate at home and abroad are PVT instrument and DBR hydrate instrument. The main parameters are as follows:

[0034] PVT instrument

[0035] Temperature: -30℃~180℃

[0036] Pressure: 0~70Mpa

[0037] DBR Hydrate Analyzer

[0038] Temperature: -30℃~180℃

[0039] Pressure 0~21MPa

[0040] The inner diameter is 2.535cm, the outer diameter is 3.81cm, and the effective volume is 75ml

[0041] The main technical indicators of the natural gas hydrate generating device of the present invention are as follows:

[0042] Withstand pressure: 0~4MPa

[0043] Power supply: 220V alternating power supply

[0044] Plexiglass cylinder: outer diameter 5.0cm, inner diameter 1.9cm, effective volume 15ml

[0045] Pt100 temperature sensor, accuracy ±0.1℃

[0046] Pressure sensor, range 0~10MPa, accuracy ±0.5%.

[0047] The temperature reduction of the natural gas hydrate generating device of the present invention is completed in the DBR wind box 3 of the PVT instrument, and the measurement temperature range is -30°C to 180°C, and the accuracy is ±0.1°C. The temperature that the instrument needs to withstand is -30℃~100℃

[0048] Studies on the stability of natural gas hydrates show that natural gas hydrates are in a metastable state, and a sudden decrease in pressure or a sudden increase in temperature will cause the rapid decomposition of natural gas hydrates. Experimental studies have shown that when the hydrate pressure is reduced by half, the amount of hydrates will be reduced by more than 85%. Therefore, the most important factor in the sampling of natural gas hydrates is to quickly disassemble them while keeping the natural gas hydrate samples cold.

[0049] Table 1 The data of gas hydrate formation temperature measured by DBR hydrate meter

[0050] Numbering 1 2 3 4 5 6 7 8 Gas Gas sample 1 Gas sample 1 Gas sample 1 Gas sample 1 Gas sample 2 Gas sample 2 Gas sample 2 Gas sample 2 Liquid sample Pure water Pure water Pure water Pure water Pure water Pure water Pure water Pure water Pressure (MPa) 2.952 5.964 8.930 11.997 2.968 5.970 8.998 11.964 Temperature (K) 276.45 281.75 284.95 286.65 277.95 285.05 287.85 289.25

[0051] Among them, methane in gas sample 1 accounts for 91.909%, and methane in gas sample 2 accounts for 86.480%.

[0052] From the above parameters, it can be analyzed that the PVT instrument, the DBR hydrate meter and the fast detachable sampling natural gas hydrate generating device of the present invention can generate natural gas hydrate within a certain temperature and pressure range.

[0053] In terms of instrument pressure, PVT instrument and DBR hydrate instrument have their advantages. Their test pressures can reach 70 MPa and 21 MPa, respectively, and can measure the phase equilibrium conditions of natural gas hydrate under high pressure.

[0054] In terms of temperature range, the temperature adjustment ranges of the three instruments are basically the same.

[0055] From the perspective of disassembly time, after the formation of natural gas hydrate, both the PVT instrument and the DBR hydrate instrument must be cooled to room temperature and the pressure dropped to 1atm before disassembly. At the same time, the depressurization process and the heating process must be slow, and cannot rise and fall suddenly, otherwise it will cause damage to the instrument, and even cause the PVT tube and the sapphire tube to rupture and scrap. Therefore, the fastest time to disassemble the PVT instrument and DBR hydrate instrument is about 20-30 minutes. In this process, the natural gas hydrate formed in the sapphire tube rapidly decomposes as the temperature rises and the pressure drops. When the disassembly was completed, the natural gas hydrate had all been decomposed. Therefore, the method of taking out natural gas hydrate samples from PVT or DBR hydrate analyzer is not advisable.

[0056] The pressure range of the natural gas hydrate generating device capable of quickly dismounting and sampling of the present invention is 0-4MPa. After the natural gas hydrate is generated, the pressure must be relieved before disassembly, but it can be carried out under low temperature conditions. At the same time, liquid nitrogen and ice cube cooling methods are used to keep the natural gas hydrate samples taken out at low temperature to delay the decomposition of natural gas hydrate. Therefore, the disassembly time of the natural gas hydrate generating device capable of quickly dismounting and sampling of the present invention is about 1 to 2 minutes.

[0057] Therefore, the natural gas hydrate generator capable of quickly dismounting and sampling of the present invention can generate natural gas hydrate under a pressure of 0-4 MPa. At the same time, the device can be quickly disassembled to take out natural gas hydrate samples for microstructure testing.

[0058] The working process of the present invention is as follows: first rinse the plexiglass cylinder 12 with distilled water and deionized water until no water drops are hung on the cylinder wall, then rinse three times with the liquid to be tested, and add 5ml 300ppm ten to the plexiglass cylinder 12. Sodium dialkyl sulfate solution, install the plexiglass cylinder 12, and then vacuum the pipeline and the plexiglass cylinder 12 for about 15 minutes, open the inlet valve and feed the sample into the reactor 1, keeping the gas pressure at the predetermined experimental pressure , Start the reversible motor 4, the reversible motor 4 of the stirring device 2 drives the reactor 1 to rotate around the motor shaft 8 through the motor shaft 8, the fixing base 5. When the fixing base 5 touches the limit switch A6, the reversible motor 4 starts to rotate in the opposite direction When the fixed seat 5 touches the limit switch B7, the reversible motor 4 rotates in the opposite direction again, and this is repeated to achieve sufficient stirring of the liquid in the reactor 1. When the natural gas hydrate is formed, keep the device in a low temperature state, open the pressure relief valve connected to the reactor 1 through the pipe fittings, after the pressure relief is completed, loosen the fastening butterfly mother, and fix the lower connecting rod 16 of the assembly 11 Bend outward from the hinge 17 and remove the lower end cap 10 to take out the natural gas hydrate and complete the sampling operation.