Treatment method of natural gas low-temperature condensate

Abstract

The invention discloses a treatment method of natural gas low-temperature condensate, and belongs to the technical field of natural gas processing and treatment. According to the method disclosed by the invention, the flash separation treatment of the low-temperature condensate and the light oil stabilizing treatment are combined, and the flash separation process of the low-temperature condensate from the self-deoiling and dehydrating device is canceled and is combined with the light oil stabilizing device, so that the existing process is simplified, the investment is reduced, the equipment arrangement space and the equipment investment are saved, the oil gas emission is eliminated, and the energy consumption is reduced. Energy conservation, emission reduction and consumption reduction are realized, and the environment quality is effectively improved; meanwhile, low-temperature condensate of natural gas is adopted to replace heat conduction oil to preheat unstabilized light oil, heat of non-condensable gas at the tower top and cooling capacity of the low-temperature condensate of a natural gas treatment plant are utilized, flash steam is recycled, light oil is stabilized through integral skid-mounted, and the device has the advantages that the occupied area is saved, and the construction period is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas processing and treatment, and in particular relates to a method for treating low-temperature condensate of natural gas. Background Art

[0002] Some heavier hydrocarbons in natural gas are in gas phase under high temperature and high pressure conditions in oil reservoirs. When gas is produced, due to the decrease in pressure and temperature, these heavier hydrocarbons condense from natural gas and become light oil. Light oil separated from gas well sites and gas phase processing facilities in natural gas processing plants are all natural gas condensate. Light oil cannot be used directly as a product and needs to be stabilized to remove light hydrocarbons that affect the saturated vapor pressure of light oil in order to control the saturated vapor pressure of light oil.

[0003] The low-temperature condensate directly enters the three-phase separator to process light oil, which is easy to cause equipment corrosion, increase the energy consumption of the device, and affect the stability of the equipment. At the same time, the emission of flash gas will cause the flare to be blocked and emit black smoke, thereby polluting the environment. The Ministry of Environmental Protection officially implemented the "Emission Standards of Air Pollutants for Onshore Petroleum and Natural Gas Exploitation Industry" (GB 39728-2020) on January 1, 2021. The standard clearly states that "5.7.3 The natural gas vented from the oil and gas field should be recovered. If it cannot be recovered or is difficult to recover, it should be vented after combustion; if it cannot be burned and vented directly, it should be reported to the ecological environment department for filing." "5.7.4 The flare system of the oil and gas centralized processing station and the natural gas processing plant shall comply with the following provisions: a) Take measures to recover the liquid discharged into the flare system; b) VOCs and natural gas entering the flare should be able to be ignited and fully burned in time; c) Continuously monitor the working status of the flare and its ignition facilities (flare gas flow, flare flame temperature, fire gas flow, fire temperature, etc.), compile monitoring records and keep them for at least 3 years.

[0004] The light oil after stabilization treatment can be used directly as fuel and is a high-quality raw material for the oil refining industry. It can be separated into petrochemical products such as ethane, propane, butane, light oil or gasoline. Therefore, it is very necessary to optimize the low-temperature condensate treatment process. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for treating low-temperature condensate of natural gas, which is used to solve the technical problems of the existing low-temperature condensate treatment methods that easily cause equipment corrosion and high energy consumption.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention discloses a method for treating low-temperature condensate of natural gas, comprising the following steps:

[0008] S1: After the cryogenic condensate is preheated in the tower top heat exchanger, the temperature of the cryogenic condensate increases, and the preheated cryogenic condensate is separated into gas phase gas, alcohol-containing water and unstabilized condensate oil through a three-phase separator;

[0009] S2: The unstabilized condensate oil produced passes through the condensate oil heat exchanger and enters the light oil stabilization tower, and forms stable condensate oil at the bottom of the light oil stabilization tower; the stable condensate oil is heated by the reboiler to form high-temperature stable condensate oil; the high-temperature stable condensate oil is cooled by the condensate oil heat exchanger and the light oil air cooler in turn, and then output to the stable light oil storage tank;

[0010] S3: The generated gas phase gas and the non-condensable gas at the top of the light oil stabilization tower form a mixed gas and enter the flash separator to obtain flash steam; the flash steam is then recovered to the raw material system;

[0011] S4: The generated alcohol-containing water is transported to the alcohol-containing wastewater receiving tank through a pipeline.

[0012] Furthermore, the generated unstabilized condensate is preheated in the light oil stabilization tower by the low-temperature condensate preheated in the tower top heat exchanger.

[0013] Furthermore, a light oil export pump is provided on the light oil air cooler and the pipeline for transporting the stable light oil to the storage tank.

[0014] Furthermore, the light oil air cooler is provided with a thermometer.

[0015] Furthermore, the mixed gas enters a flash separator, and after flash gas is formed, the flash gas is pressurized and then recovered to the raw material system.

[0016] Furthermore, the pressurization treatment is performed using a flash separator.

[0017] Furthermore, the reboiler is heated by an electric heater.

[0018] Furthermore, the water content in the three-phase separator is 0.5% to 1%.

[0019] Furthermore, the water content in the three-phase separator is 0.5%.

[0020] Furthermore, a thermometer is also provided in the reboiler.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The invention discloses a method for treating low-temperature condensate of natural gas, which combines flash separation treatment of low-temperature condensate with light oil stabilization treatment, recovers flash gas of a three-phase separator and a light oil stabilization tower in a light oil stabilization device during the treatment process into raw gas through pressurization, cancels the flash separation process of low-temperature condensate from a de-oiling and dehydration device, and combines it with the light oil stabilization device, thereby simplifying the existing process, reducing investment, saving equipment layout space and equipment investment, eliminating oil and gas emissions, achieving energy conservation and emission reduction, and effectively improving environmental quality; at the same time, low-temperature condensate of natural gas is used instead of heat transfer oil to preheat unstable light oil, utilizes the heat of non-condensable gas at the top of the tower and the coldness of low-temperature condensate of a natural gas processing plant, and preheats the unstable light oil entering the tower to save energy.

[0023] Furthermore, the water content in the three-phase separator is adjusted to 0.5%, which can reduce the heating load of the three-phase separator and reduce energy consumption.

[0024] Furthermore, the light oil stabilizer adopts electric heaters to simplify the heating process, and the flash gas recovery and light oil stabilizer adopt overall skid-mounted installation, which saves floor space and construction period, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic flow chart of a method for treating low-temperature condensate of natural gas according to the present invention;

[0026] Among them: 1-tower top heat exchanger; 2-three-phase separator; 3-light oil stabilization tower; 4-condensate oil heat exchanger; 5-reboiler; 6-light oil air cooler; 7-flash separator; 8-light oil export pump. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] like Figure 1 As shown, the present invention discloses a method for treating low-temperature condensate of natural gas, which adopts a combined low-temperature condensate treatment process of "low-temperature condensate flash separation + light oil stabilization device", and recovers the flash gas of the three-phase separator 2 and the light oil stabilization tower 3 into the raw gas through pressurization, and at the same time adjusts the water content in the three-phase separator 2 to 0.5%.

[0030] Specifically, the following steps are included: after the cryogenic condensate is preheated in the tower top heat exchanger 1, the temperature of the cryogenic condensate is increased, and the preheated cryogenic condensate is separated into gas phase gas, alcohol-containing water and unstabilized condensate oil by passing through a three-phase separator 2;

[0031] The generated unstabilized condensate passes through the condensate heat exchanger 4 and enters the light oil stabilization tower 3, and forms a stable condensate at the bottom of the light oil stabilization tower 3; the stable condensate is heated by the reboiler 5 to form a high-temperature stable condensate; the high-temperature stable condensate is cooled by the condensate heat exchanger 4 and the light oil air cooler 6 in sequence, and is output to the stable light oil storage tank;

[0032] The generated gas phase gas and the non-condensable gas at the top of the light oil stabilization tower 3 form a mixed gas and enter the flash separator 7 to obtain flash steam; then the flash steam enters the flash separator 7 for pressurization and is recovered to the raw material system;

[0033] The generated alcohol-containing water is transported through a pipeline to the alcohol-containing wastewater receiving tank.

[0034] The combined low-temperature condensate treatment process of "low-temperature condensate flash separation + light oil stabilization device" described in the solution provided by the present invention eliminates the flash separation process of the low-temperature condensate coming out of the de-oiling and dehydration device.

[0035] The scheme provided by the present invention describes that the flash gas of the three-phase separator 2 and the light oil stabilization tower 3 in the light oil stabilization device is recovered into the raw gas by pressurization.

[0036] The solution provided by the present invention uses the low-temperature condensate of natural gas instead of the heat transfer oil to preheat the unstable light oil, which means that the low-temperature condensate of the three-phase separator 2 exchanges heat with the non-condensable gas at the top of the tower, utilizing the heat of the non-condensable gas at the top of the tower and the cold capacity of the low-temperature condensate of the natural gas processing plant, while preheating the unstable light oil entering the tower to save energy.

[0037] The water content in the three-phase separator 2 described in the solution provided by the present invention is adjusted to 0.5%, which can reduce the heating load of the three-phase separator and reduce energy consumption.

[0038] The optimized natural gas low-temperature condensate treatment process obtained by the treatment method of the present invention meets the relevant requirements of the "Onshore Petroleum and Natural Gas Exploitation Industry Pollutant Emission Standard" GB 39728-2020, while optimizing the process and saving space.

[0039] Example

[0040] A method for processing low-temperature condensate of natural gas comprises the following steps:

[0041] The combined low-temperature condensate treatment process of "low-temperature condensate flash separation + light oil stabilization device" is adopted, and the flash gas from the three-phase separator 2 and the light oil stabilization tower 3 is recovered into the raw gas through pressurization, and the natural gas low-temperature condensate replaces the heat transfer oil to preheat the unstable light oil; during the whole process, the water content in the three-phase separator 2 is adjusted to 0.5%.

[0042] The combined low-temperature condensate treatment process of "low-temperature condensate flash separation + light oil stabilization device" described in the solution provided by the present invention cancels the low-temperature condensate flash separation process from the deoiling and dehydration device, and merges it with the light oil stabilization device, thereby simplifying the existing process and reducing investment.

[0043] The scheme provided by the present invention describes that the flash gas of the three-phase separator 2 and the light oil stabilization tower 3 in the light oil stabilization device is recovered into the raw gas by pressurization, which not only eliminates oil and gas emissions, achieves energy conservation and emission reduction, energy conservation and consumption reduction, but also effectively improves environmental quality.

[0044] The solution provided by the present invention uses the low-temperature condensate of natural gas instead of the heat transfer oil to preheat the unstable light oil, which means that the low-temperature condensate of the three-phase separator 2 exchanges heat with the non-condensable gas at the top of the tower, utilizing the heat of the non-condensable gas at the top of the tower and the cold capacity of the low-temperature condensate of the natural gas processing plant, while preheating the unstable light oil entering the tower to save energy.

[0045] The water content in the three-phase separator 2 described in the solution provided by the present invention is adjusted to 0.5%, which can reduce the heating load of the three-phase separator and reduce energy consumption.

[0046] The optimized natural gas cryogenic condensate treatment process meets the relevant requirements of the "Onshore Petroleum and Natural Gas Exploitation Industry Pollutant Emission Standard" GB 39728-2020, while optimizing the process and saving space.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] The low-temperature condensate flash separator is combined with the light oil stabilization buffer tank to save equipment layout space and equipment investment; the light oil stabilization uses an electric heater to simplify the heating process; the flash gas recovery and light oil stabilization are skid-mounted as a whole to save floor space and construction period.

[0049] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for treating low-temperature condensate of natural gas, characterized in that: The following steps are involved: S1: After the cryogenic condensate is preheated in the tower top heat exchanger (1), the temperature of the cryogenic condensate increases, and the preheated cryogenic condensate passes through a three-phase separator (2) to separate into gas phase gas, alcohol-containing water and unstabilized condensate oil; S2: the generated unstabilized condensate oil passes through the condensate oil heat exchanger (4) and enters the light oil stabilization tower (3), and forms a stable condensate oil at the bottom of the light oil stabilization tower (3); the stable condensate oil passes through the reboiler (5) to heat and form a high-temperature stable condensate oil; the high-temperature stable condensate oil passes through the condensate oil heat exchanger (4) and the light oil air cooler (6) in turn to cool down, and is output to the stable light oil storage tank; S3: The generated gas phase gas and the non-condensable gas at the top of the light oil stabilization tower (3) form a mixed gas and enter the flash separator (7) to obtain flash steam; the flash steam is then recovered to the raw material system; S4: The generated alcohol-containing water is transported to the alcohol-containing wastewater receiving tank through a pipeline.

2. The method for processing low-temperature condensate of natural gas according to claim 1, characterized in that: The generated unstabilized condensate is preheated in the light oil stabilization tower (3) by the low-temperature condensate preheated in the tower top heat exchanger (1).

3. The method for processing low-temperature condensate of natural gas according to claim 1, characterized in that: The light oil air cooler (6) and the pipeline for transporting the stable light oil to the storage tank are provided with a light oil export pump (8).

4. The method for processing low-temperature condensate of natural gas according to claim 1, characterized in that: The light oil air cooler (6) is provided with a thermometer.

5. The method for processing low-temperature condensate of natural gas according to claim 1, characterized in that: The mixed gas enters the flash separator (7), and after flash gas is formed, the flash gas is pressurized and then recovered to the raw material system.

6. The method for processing low-temperature condensate of natural gas according to claim 5, characterized in that: The pressure-increasing treatment is carried out using a flash separator (7).

7. The method for processing low-temperature condensate of natural gas according to claim 1, characterized in that: The reboiler (5) is heated by an electric heater.

8. The method for processing low-temperature condensate of natural gas according to claim 1, characterized in that: The water content in the three-phase separator (2) is 0.5% to 1%.

9. The method for processing low-temperature condensate of natural gas according to claim 8, characterized in that: The water content in the three-phase separator (2) is 0.5%.

10. The method for processing low-temperature condensate of natural gas according to claim 1, characterized in that: The reboiler (5) is also provided with a thermometer.

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