KR100720270B1 - Continuous Production System of Natural Gas Hydrate - Google Patents

Abstract

The present invention relates to a method of continuously producing a natural gas hydrate using natural gas and ice water, and to minimize the heat generated when the natural gas hydrate is produced by using the self cooling effect of the gas with the use of ice water in a short time It is to provide a method for producing a natural gas hydrate.

The present invention in the production of a continuous natural gas hydrate,

In the main continuous hydrate manufacturing apparatus, the ice water is continuously mixed with the natural gas through a nozzle installed vertically with the high pressure gas nozzle by expanding the high pressure natural gas, and the ice water and the natural gas are expanded to hydrate. By using the effect of the post-compression to improve the rate of hydrate production, to produce the natural gas hydrate of the unreacted natural gas through the auxiliary continuous hydrate maker, connecting the main continuous hydrate manufacturing apparatus and the auxiliary continuous hydrate manufacturing apparatus By the production of natural gas hydrate in a multi-stage, the method and apparatus for producing the natural gas hydrate continuously and its technical features.

Continuous Natural Gas Hydrate, Ice Water Production Equipment

Description

Continuous Production System of Natural Gas Hydrate             

1 is a natural gas hydrate production process according to the present invention,

Figure 2 is a detailed view of the ice water production apparatus according to the present invention,

3 is a detailed view of a continuous hydrate manufacturing apparatus used in the present invention.

<Description of the symbols for the main parts of the drawings>

(1): Natural gas pretreatment system

(2): natural gas

(3): heat exchanger for supply gas cooling

(4): seawater used as cooling water

(5): natural gas passed through the cooler

(6): gas expander

(7): natural gas through the expander

(8): supply gas pressure regulating valve                 

(9): pressure controller

(10): Natural gas passed through the pressure regulating valve

(11): main continuous hydrate maker

(12) hydrate + natural gas

(13): natural gas hydrate separator

(14): unreacted natural gas

(15): compressor

(16): unreacted circulating gas primary cooler

(17): unreacted circulating gas secondary cooler

(18): auxiliary continuous hydrate maker

(19): number of raw materials

20: raw material water flow controller

21: raw water flow control valve

(22): ice-water manufacturing equipment

23: main cooling system

(24): Extruder

(25): ice water + hydrate

(26): natural gas hydrate

(27): ice-water making apparatus equipped with spiral tubes

(28): natural gas introduction nozzle                 

(29): Ice water or (ice water + hydrate) introduction nozzle

The present invention relates to a method and apparatus for continuously producing natural gas hydrates.

When natural gas and water are brought into contact with each other under high pressure and low temperature, lattice bodies occupied by natural gas are created between the lattice made by water particles, which is called natural gas hydrate. Conventional natural gas hydrate manufacturing method is that the high pressure cooled natural gas supplied through the gas nozzle installed at the top of the reactor is in contact with the water injected through the nozzle installed below or the porous plate installed at the bottom of the reactor to produce the natural gas hydrate Bubbling is most common. Natural gas hydrate formation reaction is exothermic, so it is necessary to remove heat generated during the reaction. To this end, all natural gas hydrate generation methods, including the bubbling method, are equipped with a cooling system in the reactor or a system for lowering the temperature of the reactor from the outside. Meanwhile, unreacted gases and liquids are recycled, which requires a compressor and a pump, and is equipped with a separator and a cooler for subcooling to separate the product. The bubbling method can cause plugging of the generated natural gas hydrate into the raw water or the natural gas injection nozzle, and when the injection plate is used, the material transfer resistance is large in the production reaction due to the large diameter of the generated raw water particles. There is this. The bubbling method is not a method of continuously generating natural gas hydrates, and thus is inappropriate when converting a large amount of natural gas into hydrates. In addition, it is difficult to separate the generated natural gas hydrate and unreacted water, and a cooling system is installed to remove heat generated during the reaction, but when the generated hydrate accumulates on the surface of the cooling system, the heat transfer efficiency decreases, and the cooling system is external. The method of installing in the disadvantage is that the reactor is inadequate when large.

As a method of compensating the disadvantages of the Bubbling method as described above, there is also a method of mixing raw water with natural gas using a line mixer and continuously generating hydrates in a reaction tube in which a cooling system is installed, but the hydrate conversion rate of natural gas is low. There is a large amount of unreacted gas requires a lot of energy in the compression process to reuse it, there is a disadvantage that the generated natural gas hydrate can be accumulated in the reaction tube.

The present invention has been made in consideration of the above problems, the object of which is a high pressure, low temperature gas is introduced through a specially produced gas nozzle in a continuous production method for mass production of natural gas hydrate and the nozzle installed vertically Through the introduction of ice water, which contains some natural gas, the natural gas hydrate is continuously produced, which improves the efficiency of natural gas hydrate conversion and the self-cooling effect of natural gas expansion. Through the reduction of cooling capacity and suction of ice water required for hydrate generation, the improvement of mixing efficiency without additional equipment and the expansion and compression of hydrated ice water and natural gas can be achieved by swelling and compressing so that hydrate can be generated and expander. Connect the compressor and compressor to the By providing a method that minimizes the amount of paper to provide a production method of mass production of natural gas hydrate in a row, and energy savings.

Natural gas hydrate continuous production method and apparatus according to the present invention in order to achieve the above object is as follows.

According to the natural gas hydrate continuous production method according to the present invention by passing the high pressure natural gas introduced from the gas field sequentially through a pretreatment system, a cooling device, an expander, a pressure control valve to make the gas suitable for the natural gas hydrate generation reaction and In the main continuous hydrate manufacturing apparatus, the ice water is continuously mixed with the natural gas through a nozzle installed perpendicular to the high pressure gas nozzle by expansion of the high pressure natural gas, and the ice water and natural in the main continuous hydrate manufacturing apparatus. Enhancing the rate of hydrate production by the effect of compressing the gas after expansion to produce hydrate, and separating the unreacted natural gas in the natural gas hydrate separator in the main continuous hydrate manufacturing apparatus and Using a cooler Producing a natural gas hydrate in an auxiliary continuous hydrate manufacturing apparatus using a uniform size of ice water made using a gas and an ice water production device, an extruder, and the gas passed through the compressor and a cooler; The main continuous hydrate manufacturing apparatus and the auxiliary continuous hydrate manufacturing apparatus are connected to each other to produce a natural gas hydrate in multiple stages.

In addition, the natural gas hydrate continuous production apparatus is as follows.

A pretreatment system device for removing carbon dioxide and hydrogen sulfide from the high pressure natural gas introduced from the gas field, a cooling device connected to the pretreatment system to lower the temperature of the high pressure natural gas using seawater, and a high pressure natural device connected to the cooling device. An expander for reducing the pressure and temperature of the gas, a natural gas pressure regulating valve and a pressure regulating controller connected to the expander so that the temperature and pressure are adapted to a production reaction condition, and a main continuous hydrate generating device connected to the pressure regulating valve. And a natural gas hydrate separator connected to the main continuous hydrate generating device to separate natural gas hydrate and unreacted gas, and a compressor connected to the natural gas hydrate separator to boost unreacted gas, and the compressor. To the gas to cool the gas Is composed of a primary circulating gas cooler and a secondary circulating gas cooler, and an auxiliary continuous hydrate manufacturing device connected to the cooler, and an ice water producing device for making raw water into ice water, and connected to the ice water producing device to form particles of ice. And an auxiliary continuous hydrate manufacturing apparatus connected to the extruder. In addition, the main cooling system for the production of ice water used for the removal of the heat generated and the cooling of the unreacted circulating gas is connected to the ice water production device, hydrate production device for the main continuous, secondary circulating gas cooler It is characterized by being configured.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows the overall process of the natural gas hydrate continuous manufacturing method using ice water according to the present invention,

The high pressure natural gas introduced from the gas field is removed by carbon dioxide and hydrogen sulfide in the pretreatment system (1) and the pretreated high pressure natural gas (2) is cooled by the cooling device (3) using sea water (4) as a refrigerant. The temperature drops to ~ 15 ℃ and the pressure drops to about 50 bar by the expander (6), the temperature also drops to -40 ~ -60 ℃, and the temperature and pressure are adjusted to suit the reaction conditions. Entering the main continuous hydrate generator 11 through the pressure regulating valve (8), separating the natural gas hydrate and unreacted gas (14) by the natural gas hydrate separator (13) and the compressor (15) boosting the unreacted gas to 50 bar, the primary circulating gas cooler 16 using the boosted gas as sea water as the refrigerant, and the secondary circulating gas cooler using antifreeze as the refrigerant ( Cooling to −10 ° C. by 17) and supplying the cooled gas to the auxiliary continuous hydrate manufacturing apparatus 18. In addition, in order to supply ice water of a certain size to the auxiliary continuous hydrate manufacturing apparatus, the raw water is produced through the ice water manufacturing apparatus 22 and the extruder 24, and the ice water is supplied to the auxiliary continuous hydrate manufacturing apparatus. In addition, the natural gas hydrate is produced by reacting with the gas cooled by the cooler, and the auxiliary continuous hydrate manufacturing apparatus is connected to the hydrate manufacturing apparatus during the main continuous operation to produce natural gas hydrate in multiple stages. In addition, the main cooling system 23 is used to produce ice water used for removing the generated heat of the main continuous hydrate production apparatus and for cooling the unreacted circulating gas.

In order to produce stable natural gas hydrates in the main continuous hydrate generators, the heat generated during the reaction must be removed. Since the method according to the present invention uses ice water mixed with fine ice particles and water in the production of natural gas hydrate, the generated heat generated during the production is reduced to about one third as compared with the case of using water of the prior art. Accordingly, the capacity of the cooler is also reduced to one third. The ice water 25 supplied to the main continuous hydrate generator is a mixture of fine ice particles, water and natural gas hydrate. The heat generated from the main continuous hydrate generator is removed by the main cooling system and the self-cooling effect of 50 bar of natural gas expansion, with a natural gas conversion rate of 30 to 50%. The natural gas hydrate 12 produced in the main continuous hydrate generator has a pressure of 10 bar at -10 ° C. 50% of the compressor energy required to boost the unreacted gas will use the energy generated in the feed gas expander 6. The boosted gas is cooled to -10 ° C by a primary circulating gas cooler 16 using sea water as a refrigerant and a secondary circulating gas cooler 17 using an antifreeze as a refrigerant, thereby providing an auxiliary continuous hydrate manufacturing apparatus. It is fed to produce some of the ice water and natural gas hydrates that have passed through the extruder.                     

The inside of the ice water production apparatus is filled with antifreeze maintained at -30 ° C, and a spirally wound tube 27 is installed to pass raw water. The ice with large particles in the ice water passing through the ice water producing apparatus is smallly crushed by the screw-type extruder 24 and supplied to the auxiliary continuous hydrate maker 18.

The main cooling system 23 required for the continuous natural gas hydrate manufacturing process according to the present invention uses an antifreeze as a refrigerant to convert raw water into ice water at 0 ° C., removes heat generated in the main continuous hydrate manufacturing apparatus, and unreacted circulation. Used for cooling gas.

2 is a detailed view of the ice water production apparatus 22 during the natural gas hydrate continuous production process. In the ice water production apparatus, spirally wound tubes are installed to improve the heat transfer efficiency between the raw water and the antifreeze, and the outside is filled with the antifreeze.

3 is a detailed view of a continuous hydrate manufacturing apparatus. The continuous hydrate manufacturing apparatus is vertically provided with a nozzle 28 through which a high pressure gas flows and a nozzle 29 into which ice water flows in, so that ice water is naturally sucked into the apparatus by expanding the gas when the high pressure natural gas passes through the gas nozzle. The hydrate is formed in the compressed gas and ice water mixture is compressed after expansion.

When 100 kg / hr of natural gas is converted to natural gas hydrate by the continuous natural gas hydrate manufacturing process according to the present invention, the material and thermal resin of the present process are calculated as follows. For ease of calculation, it is assumed that natural gas is 100% methane.

Natural gas 100 kg / hr: 6,250 mol / hr

Number of moles and mass of water required: 6.250 × 5.75 = 35937.5 mol / hr = 646.9 kg / hr

Assuming that the conversion rate of natural gas in this process is 50%, the mass of water required for natural gas hydrate production is 323.45 kg / hr, which is half the value calculated above. When natural gas hydrate is produced using ice, the generated heat per mole of hydrate is 19.92 kJ / mol, so when 100 kg / hr of natural gas is converted to natural gas hydrate, the generated heat is as follows.

Energy required for cooling feed gas: 5,766 kJ / hr

Energy generated by the expander: 8,366 kJ / hr

When all 100 kg / hr of feed gas are converted into hydrates, the hydrate generated heat is 6,250 × 19.92 = 1.107 × 10 ⁵ kJ / hr.

Generated heat at conversion of 50%: 6.34 × 10 ⁴ kJ / hr

Heat absorption by gas expansion of 100 kg / hr: 2.212 × 10 ⁴ kJ / hr

Cooler capacity required when considering the cooling effect of gas expansion:

^{6.225 × 10 4 kJ / hr -} 2.212 × 10 4 kJ / hr = 4.013 × 10 4 kJ / hr

The unreacted natural gas separated from the natural gas hydrate separator is 50 kg / hr, the pressure and temperature are 10 bar and -10 ℃, so the compressor capacity required to boost the pressure to 50 bar using the compressor is 1.719 × 10 ⁴ kJ / hr. Of these, 8,366 kJ / hr uses the energy generated by the expander, so the energy that must be applied externally is as follows.

1.719 × 10 ⁴ kJ / hr-8,366 kJ / hr = 8,824 kJ / hr

The capacity of the cooler to cool hot gas at 50 bar and 142.3 ° C through the compressor is as follows.

2.010 × 10 ⁴ kJ / hr

323.45 kJ / hr, chiller capacity to make 10 ° C ice water

1.36 × 10 ⁴ kJ / hr minimum

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims. Of course, such changes will fall within the scope of the claims.

As such, the present invention can continuously produce natural gas hydrates. By arranging the gas pipe where the high pressure gas flows and the ice water flow tube vertically, it mixes with the ice water naturally when the high pressure gas expands as it passes through the pipe. No device needed.

In addition, by using ice water mixed with fine ice particles and water in the production of natural gas hydrate, the capacity of the cooler required to remove the generated heat during the production reaction can be greatly reduced, and the required cooling capacity is also reduced by the self-cooling effect of the gas expansion. Can be. Part of the energy of the compressor required for boosting the unreacted gas is used to generate energy from the expander used to depressurize the supply natural gas, thereby reducing the energy required for natural gas hydrate generation.

Claims (5)

A method of producing natural gas hydrates; The high pressure natural gas from the gas field is sequentially passed through a pretreatment system, a cooling device, an expander, and a pressure regulating valve to make the gas suitable for a natural gas hydrate generation reaction, and the high pressure natural gas in the main continuous hydrate manufacturing apparatus. Ice water is continuously mixed with the natural gas through a nozzle installed perpendicular to the high-pressure gas nozzle by the expansion of the expansion and compressing the ice water and natural gas after the expansion so that the hydrate can be produced in the main continuous hydrate manufacturing apparatus Improving the rate of hydrate production using the effect; separating unreacted natural gas in the natural gas hydrate separator in the main continuous hydrate manufacturing apparatus and reusing it using a compressor and a cooler; Gas and ice water through the compressor and cooler A natural gas hydrate is produced in an auxiliary continuous hydrate manufacturing apparatus using a uniform size of ice water made using a manufacturing apparatus and an extruder, and the main continuous hydrate manufacturing apparatus and the auxiliary continuous hydrate manufacturing apparatus are connected. Natural gas hydrate is characterized in that it comprises a step of producing a natural gas hydrate in a multi-stage continuous manufacturing method. The method of claim 1; Natural gas hydrate continuous manufacturing method comprising the method of improving the heat transfer efficiency between the ice water and the antifreeze using a spirally wound tube in the step of producing the ice water for the production reaction using the ice water production apparatus. The method of claim 1; Natural gas hydrate continuous manufacturing method comprising the step of producing ice water containing ice particles of a predetermined size using the extruder in the step of obtaining a uniform ice water using the extruder. The method of claim 1; In the step of separating the unreacted natural gas in the natural gas hydrate separator and reusing it by using a compressor and a cooler, a part of the energy of the compressor for boosting the unreacted natural gas is converted into energy generated by the expander. Natural gas hydrate continuous production method including the method of using. An apparatus for producing natural gas hydrates; A pretreatment system device for removing carbon dioxide and hydrogen sulfide from the high pressure natural gas introduced from the gas field, a cooling device connected to the pretreatment system to lower the temperature of the high pressure natural gas using sea water, and a high pressure device connected to the cooling device. An expander for reducing the pressure and temperature of the natural gas, a natural gas pressure regulating valve and a pressure regulating controller connected to the expander so that the temperature and pressure are adapted to a production reaction condition, and a main continuous hydrate connected to the pressure regulating valve. A natural gas hydrate separator connected to the main continuous hydrate generating device to separate the natural gas hydrate and the unreacted gas; a compressor connected to the natural gas hydrate separator to boost the unreacted gas; Connected with the purifier to cool the gas Is composed of a primary circulating gas cooler and a secondary circulating gas cooler, an auxiliary continuous hydrate manufacturing apparatus connected to the cooler, and an ice water manufacturing apparatus for making raw water into ice water, and connected with the ice water manufacturing apparatus to collect particles of ice. A constant extruder and an auxiliary continuous hydrate manufacturing apparatus connected to the extruder. In addition, the main cooling system for producing ice water used for removing the generated heat and cooling of the unreacted circulating gas is connected to the ice water production device, hydrate production device for the main continuous, secondary circulating gas cooler Natural gas hydrate continuous production apparatus, characterized in that the configuration.

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