A natural gas pipeline antifreeze device and method utilizing pressure energy to release heat

Abstract

A natural gas pipeline antifreeze device and method utilizing pressure energy to release heat, the device is composed of a natural gas inlet pipeline, a convergent nozzle, a separation device, a water vapor collection device, a front step pipeline, a converging nozzle, a natural gas outlet pipeline, a separated heat pipe and a shell; the device is placed on an open ground, and the natural gas from the gas well is introduced from the inlet pipeline. The natural gas pipeline can be heated and antifreeze by utilizing the high pressure of the natural gas through the comprehensive utilization of the convergent nozzle and the front step pipeline. The present invention utilizes the high pressure of natural gas to obtain high-speed natural gas, and uses a deceleration and temperature increase method to make the natural gas generate a large amount of heat. Compared with traditional natural gas antifreeze methods, it achieves lower cost and more efficient pipeline antifreeze, reduces the space occupied by equipment, and saves materials.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas pipeline antifreeze blocking, and in particular to a natural gas pipeline antifreeze device and method utilizing pressure energy to release heat. Background Art

[0002] In the process of energy structure transformation, natural gas will play an increasingly important role as a bridge, and promoting the growth of natural gas consumption and industrial development is the only way for China to build a clean energy system. However, in the process of natural gas extraction and utilization, natural gas will contain water, which is not conducive to the use and transportation of natural gas.

[0003] In the traditional production process, the natural gas dehydration and antifreeze technology mainly includes solvent absorption method, solid adsorption method, etc. The essence of solvent absorption method is to use dehydration solvent with strong water absorption capacity and weak natural gas absorption capacity to achieve gas-liquid mass transfer and water removal in the adsorption tower; but the whole dehydration system is too complicated, the absorbent is easily damaged and the regeneration energy consumption is large, and the investment cost and operation cost are high. The basic principle of solid adsorption method is to use the absorption tension of desiccant to absorb water molecules in natural gas into the inner pores of desiccant to eliminate water; but the price of molecular sieve dehydration equipment is expensive, and it is limited by the pressure ratio, and there is a large amount of methane loss, so the economic efficiency is poor. Summary of the invention

[0004] In order to overcome the problems existing in the prior art, the purpose of the present invention is to provide a natural gas pipeline heating device and method that comprehensively utilizes a convergent-divergent nozzle and a front step pipeline. The device utilizes the high-pressure natural gas of the gas well, expands and accelerates the natural gas through the convergent-divergent nozzle, and then heats the natural gas through the front step structure to prevent the formation of natural gas hydrates at the wellhead due to throttling and pressure regulation, thereby avoiding pipeline freezing and blockage, and achieving lower cost and more efficient natural gas pipeline antifreeze.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A natural gas pipeline antifreeze device utilizing pressure energy to release heat, the device comprising a natural gas inlet pipeline 1, a convergent nozzle 2, a separation device 3, a water vapor collection device 4, a front step pipeline 5, a convergent nozzle 6, a natural gas outlet pipeline 7, a separated heat pipe 8 and a shell 9;

[0007] Natural gas enters the inlet pipe 1, and the inlet pipe 1 is connected to one end of the convergent-divergent nozzle 2; the other end of the convergent-divergent nozzle 2 is connected to one end of the separation device 3; the separation device 3 is a curved pipe, and a plurality of small holes are opened on the outer wall of the curved pipe, and the outer side of the curved pipe is connected to the water vapor collecting device 4; the other end of the separation device 3 is connected to one end of the front step pipe 5; the other end of the front step pipe 5 is connected to the large opening end of the convergent nozzle 6; the small opening end of the convergent nozzle 6 is connected to the left outlet pipe 7; finally, the outlet pipe 7 transports the natural gas to the downstream processing plant; the separated heat pipe 8 is located between the convergent-divergent nozzle 2 and the front step pipe 5; the shell 9 wraps the device.

[0008] The separation device 3 is located between the divergent nozzle 2 and the front step pipeline 5. The outer wall surface of the curved pipe part of the separation device 3 connected to the water vapor collecting device 4 is provided with a plurality of small holes to facilitate the water vapor separation of the natural gas containing water at the curved pipe through centrifugal force. At the same time, the small holes are filled with a highly hydrophilic resin material. The highly hydrophilic resin material allows water to pass through and can prevent the natural gas from escaping through the small holes, so that the water vapor in the natural gas can be efficiently separated at the curved pipe.

[0009] The highly hydrophilic resin material is a high polymer that can quickly absorb a large amount of water and block other substances from passing through, thereby playing a role in removing water, such as polyacrylate, starch acrylate polymer, starch-acrylonitrile graft copolymer or acrylamide-acrylonitrile-acrylic acid terpolymer.

[0010] The separated heat pipe 8 is located between the divergent nozzle 2 and the front step pipeline 5. A section of the heat pipe in the separated heat pipe 8 close to the front step pipeline 5 contains a liquid wick to form the heat pipe evaporation section, and the liquid wick is made of capillary porous material; the interior of the heat pipe is evacuated into a negative pressure state and filled with a liquid working medium with a low boiling point and high volatility; when the separated heat pipe 8 is working, the liquid working medium flows in the pipe, and the high Mach number natural gas generates a shock wave and a large amount of heat while passing through the front step pipeline 5, so that the part of the heat pipe containing the liquid wick is heated, and the liquid working medium in the liquid wick evaporates rapidly, and the vapor flows to the other end under a small pressure difference and releases heat, which is transferred to the divergent nozzle 2 and condensed into liquid again. The liquid then flows back to the evaporation section along the liquid wick by the action of capillary force, and the cycle continues. The heat is transferred from one end of the heat pipe to the other end, and the high heat part at the front step pipeline 5 is transferred to the divergent nozzle 2 to prevent freezing and blockage in the divergent nozzle 2.

[0011] The capillary porous material is a solid containing a certain number of holes. In the present invention, the capillary porous material is made by foaming materials such as ceramics or glass.

[0012] The liquid working fluid with low boiling point and high volatility can be ether, ethanol, acetone, petroleum ether or water.

[0013] The convergent nozzle 6 is connected to the outlet pipe 7 and is used to increase the pressure of the natural gas obtained after the front step pipe 5 is heated and dehydrated.

[0014] First, the natural gas is accelerated to hypersonic speed by the convergent-convergent nozzle 2, and then passed into the front step pipeline 5 after being processed by the separation device 3, where a shock wave is generated and the temperature increases sharply, thus heating the natural gas.

[0015] The working method of the natural gas pipeline antifreeze device utilizing pressure energy to release heat comprises the following steps:

[0016] Step 1, placing a natural gas pipeline antifreeze device that uses pressure energy to release heat on an open ground, and then introducing high-pressure natural gas through a natural gas inlet pipeline 1 into a reduced-pressure accelerated convergent-divergent nozzle 2; accelerating the natural gas to hypersonic speed through the convergent-divergent nozzle 2;

[0017] Step 2: the separation device 3 discharges water vapor in the natural gas through the bend, and then collects it in the water vapor collection device 4; the natural gas then passes through the front step pipeline 5, and the supersonic natural gas forms a shock wave in the front step pipeline 5. When the natural gas passes through the shock wave, the speed and pressure are significantly reduced, and the temperature is greatly increased;

[0018] Step 3, placing a separate heat pipe 8 between the front step nozzle 5 and the convergent-divergent nozzle 2, the separate heat pipe 8 transfers the high temperature heat generated by the front step nozzle 5 to the convergent-divergent nozzle 2, to prevent the convergent-divergent nozzle 2 from freezing due to excessively low temperature caused by decompression acceleration;

[0019] In step 4, the natural gas after passing through the front step pipeline 5 enters the convergent nozzle 6 to restore the pressure of the natural gas, and finally the natural gas is transported to the downstream processing plant through the natural gas outlet pipeline 7 to achieve efficient and low-cost heating of the natural gas.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The combination of the convergent nozzle and the front step pipeline makes the structure of the heating device simpler, reduces the steel consumption per unit production cost, and has the advantages of high reliability and low investment. The separation device utilizes the highly hydrophilic resin material on the outside of the elbow and the centrifugal force to remove moisture from the natural gas, and the structure is simple and compact. The present invention also uses a separate heat pipe, which can fully utilize the energy of the natural gas itself to prevent freezing and blockage of the natural gas pipeline, and the energy utilization efficiency is higher. The present invention also uses a convergent nozzle at the end of the device, which can pressurize the treated natural gas, which is beneficial to the utilization of the natural gas in the downstream processing plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1The present invention is a schematic diagram of a natural gas pipeline antifreeze device that utilizes pressure energy to release heat.

[0023] Figure 2 It is a schematic diagram of the outer structure of the elbow in the separation device of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] like Figure 1 As shown, the present invention is a device for preventing natural gas pipelines from freezing by utilizing pressure energy to release heat, and the device is composed of a natural gas inlet pipeline 1, a convergent nozzle 2, a separation device 3, a water vapor collecting device 4, a front step pipeline 5, a converging nozzle 6, a natural gas outlet pipeline 7, a separation type heat pipe 8, and a shell 9; the high-pressure natural gas from the gas well is introduced into the left end of the convergent nozzle 2 through the natural gas inlet pipeline 1; the right end of the convergent nozzle 2 is connected to the separation device 3; a plurality of small holes are opened on the outer side of the bent pipe of the separation device 3 and are connected to the water vapor collecting device 4; the other side of the separation device 3 is connected to the front step pipeline 5; the front step pipeline 5 is connected to the converging nozzle 6 at the left end; the other end of the converging nozzle 6 is then connected to the natural gas outlet pipeline 7 at the left end; finally, the natural gas is transported to the downstream processing plant through the outlet pipeline 7; the separation type heat pipe 8 is located between the bottom of the convergent nozzle 2 and the top of the front step pipeline 5; and the shell 9 wraps the entire device.

[0026] like Figure 1 As shown, a section of the heat pipe near the front step 5 in the separated heat pipe 8 contains a liquid wick, which is made of capillary porous materials such as ceramics or glass. The inside of the heat pipe is pumped into a negative pressure state and filled with a suitable liquid, such as ether, ethanol, acetone, petroleum ether or water. This liquid has a low boiling point and is easy to volatilize. When the separated heat pipe 8 is working, the working medium in the pipe flows clockwise, and the high Mach number natural gas generates a shock wave and a large amount of heat through the front step pipeline 5, so that the part of the heat pipe containing the liquid wick is heated, and the liquid in the liquid wick evaporates rapidly. The steam flows to the other end under a small pressure difference and releases heat, which is transferred to the convergent nozzle 2 and condensed into liquid again. The liquid then flows back to the evaporation section along the liquid wick by the action of capillary force, and the cycle continues. The heat is transferred from one end of the heat pipe to the other end. Doing so can prevent the gas expansion acceleration in the convergent nozzle 2 from causing the temperature to drop, causing the natural gas pipeline to freeze.

[0027] like Figure 2As shown, the outer wall surface of the curved pipe portion of the separation device 3 connected to the water vapor collecting device 4 is provided with a plurality of small holes to facilitate the separation of water vapor from the natural gas containing water at the curved pipe by centrifugal force. At the same time, the small holes are filled with highly hydrophilic resin materials such as polyacrylates, starch acrylate polymers, starch-acrylonitrile graft copolymers or acrylamide-acrylonitrile-acrylic acid terpolymers. The highly hydrophilic resin materials allow water to pass through and can prevent the natural gas from escaping through the small holes, so that water vapor in the natural gas can be efficiently separated at the curved pipe.

[0028] Example: Heating and anti-freezing of wellhead natural gas pipeline:

[0029] (1) Figure 1 As shown, a natural gas pipeline antifreeze device that utilizes pressure energy to release heat is placed on an open ground, and high-pressure natural gas in a gas well is introduced into a convergent-divergent nozzle 2 for decompression and acceleration through a natural gas inlet pipeline 1; the natural gas is accelerated to a hypersonic speed through the convergent-divergent nozzle 2, and water vapor in the natural gas is discharged through a separation device 3 and collected in a water vapor collection device 4;

[0030] (2) Figure 1 As shown, the natural gas flowing out of the separation device 3 passes through the front step pipeline 5, and the supersonic natural gas can form a shock wave in the front step. When the natural gas passes through the shock wave, the speed and pressure are significantly reduced, and the temperature is greatly increased; the gas after passing through the front step pipeline 5 enters the convergent nozzle 6, so that the pressure of the natural gas is restored, and finally the natural gas is transported to the downstream processing plant through the outlet pipeline 7;

[0031] (3) Figure 1 As shown, a separate heat pipe 8 is placed between the front step nozzle 5 and the divergent nozzle 2, which can transfer the high-temperature heat generated by the front step nozzle 5 to the divergent nozzle 2 to prevent the divergent nozzle 2 from freezing and blocking the natural gas pipeline due to excessively low temperature caused by the decompression and acceleration.

Claims

1. A natural gas pipeline antifreeze device that utilizes pressure energy to release heat, characterized in that: The device is composed of a natural gas inlet pipeline (1), a convergent nozzle (2), a separation device (3), a water vapor collection device (4), a front step pipeline (5), a convergent nozzle (6), a natural gas outlet pipeline (7), a separated heat pipe (8) and a shell (9); The natural gas enters an inlet pipe (1), and the inlet pipe (1) is connected to one end of a convergent-divergent nozzle (2); the other end of the convergent-divergent nozzle (2) is connected to one end of a separation device (3); the separation device (3) is a curved pipe, and a plurality of small holes are opened on the outer wall of the curved pipe, and the outer side of the curved pipe is connected to a water vapor collecting device (4); the other end of the separation device (3) is connected to one end of a front step pipe (5); the other end of the front step pipe (5) is connected to the large opening end of a converging nozzle (6); the small opening end of the converging nozzle (6) is connected to a natural gas outlet pipe (7); finally, the outlet pipe (7) transports the natural gas to a downstream processing plant; the separation heat pipe (8) is located between the convergent-diverging nozzle (2) and the front step pipe (5); and the shell (9) wraps the entire device; A section of the heat pipe near the front step pipe (5) in the separated heat pipe (8) contains a liquid wick to form the heat pipe evaporation section, and the liquid wick is made of a capillary porous material; the interior of the heat pipe is evacuated into a negative pressure state, and a liquid working medium with a low boiling point and high volatility is filled in; when the separated heat pipe (8) is in operation, the liquid working medium flows in the pipe, and the high Mach number natural gas generates a shock wave and a large amount of heat while passing through the front step pipe (5), so that the part of the heat pipe containing the liquid wick is heated, and the liquid working medium in the liquid wick evaporates rapidly, and the vapor flows to the other end under a small pressure difference and releases heat, which is transferred to the convergent nozzle (2) and condensed into liquid again. The liquid then flows back to the evaporation section along the liquid wick by the action of capillary force, and the cycle continues. Heat is transferred from one end of the heat pipe to the other end, and the high heat part at the front step pipe (5) is transferred to the convergent nozzle (2), so as to prevent freezing and blockage in the convergent nozzle (2).

2. A natural gas pipeline antifreeze device utilizing pressure energy to release heat according to claim 1, characterized in that: The separation device (3) is located between the convergent-divergent nozzle (2) and the front step pipeline (5). The outer wall surface of the curved pipe portion of the separation device (3) connected to the water vapor collecting device (4) is provided with a plurality of small holes to facilitate the separation of water vapor from the natural gas containing water at the curved pipe by centrifugal force. At the same time, the small holes are filled with a highly hydrophilic resin material. The highly hydrophilic resin material allows water to pass through and can prevent the natural gas from escaping through the small holes, so that water vapor in the natural gas can be efficiently separated at the curved pipe.

3. A natural gas pipeline antifreeze device utilizing pressure energy to release heat according to claim 2, characterized in that: The highly hydrophilic resin material is polyacrylic acid salt, starch acrylate polymer, starch-acrylonitrile graft copolymer or acrylamide-acrylonitrile-acrylic acid terpolymer.

4. The natural gas pipeline antifreeze device utilizing pressure energy to release heat according to claim 1, characterized in that: The capillary porous material is a solid containing a certain number of holes and is made by foaming ceramic or glass materials.

5. The natural gas pipeline antifreeze device utilizing pressure energy to release heat according to claim 1, characterized in that: The liquid working medium with low boiling point and high volatility is ether, ethanol, acetone, petroleum ether or water.

6. The natural gas pipeline antifreeze device utilizing pressure energy to release heat according to claim 1, characterized in that: The converging nozzle (6) is connected to the outlet pipeline (7) and is used to increase the pressure of the natural gas obtained after heating and removing water from the front step pipeline (5).

7. The natural gas pipeline antifreeze device utilizing pressure energy to release heat according to claim 1, characterized in that: First, the natural gas is accelerated to a hypersonic speed through the convergent-convergent nozzle (2), and then passed into the front step pipeline (5) after being processed by the separation device (3), where a shock wave is generated and the temperature increases sharply, thereby heating the natural gas.

8. The working method of a natural gas pipeline antifreeze device utilizing pressure energy to release heat according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1, placing a natural gas pipeline antifreeze device that utilizes pressure energy to release heat on an open ground, and then introducing high-pressure natural gas into a reduced-pressure accelerating convergent-divergent nozzle (2) through a natural gas inlet pipeline (1); accelerating the natural gas to a hypersonic speed through the convergent-divergent nozzle (2); Step 2, the separation device (3) discharges water vapor in the natural gas through the bend, and then collects it in the water vapor collection device (4); the natural gas then passes through the front step pipeline (5), and the supersonic natural gas forms a shock wave in the front step pipeline (5). When the natural gas passes through the shock wave, the speed and pressure of the natural gas are significantly reduced, and the temperature is greatly increased; Step 3, placing a separate heat pipe (8) between the front step pipe (5) and the convergent-divergent nozzle (2), wherein the separate heat pipe (8) transfers the high temperature heat generated by the front step pipe (5) to the convergent-divergent nozzle (2), thereby preventing the convergent-divergent nozzle (2) from freezing due to excessively low temperature caused by accelerated decompression; Step 4, the natural gas after passing through the front step pipeline (5) enters the convergent nozzle (6) to restore the pressure of the natural gas, and finally the natural gas is transported to the downstream processing plant through the natural gas outlet pipeline (7), thereby achieving efficient and low-cost heating of the natural gas.

Images