A system and process for recovering qualified stable light hydrocarbons in a flash stabilization process

Abstract

This invention pertains to the field of oil and gas, disclosing a system and process for recovering qualified stabilized light hydrocarbons in a flash stabilization process. The system includes a crude oil buffer tank, a flash stabilization tower module, a primary cooling and separation module for stabilized gas, and a secondary flash stabilization and separation module for light oil. In the primary cooling and separation module, one pipe of the stabilized gas cooler is connected to the crude oil stabilization tower in the flash stabilization tower module, and another pipe is connected to the stabilized gas separator in the primary cooling and separation module. One pipe of the stabilized gas separator is connected to the light oil separator, and the other is connected to the outlet B of the booster pump in the flash stabilization tower module. The light oil separator in the secondary flash stabilization and separation module has three main pipes: one connected to the stabilized gas separator, one connected to the wastewater treatment system, and the other connected to the light oil storage tank. This invention employs primary cooling separation and secondary flash stabilization separation, controlling the saturated vapor pressure of the stabilized light hydrocarbons below 0.2 MPa, meeting the relevant specifications for saturated vapor pressure.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas and is applied to the flash stabilization process. It is a process method for recovering stable light hydrocarbons, specifically a system and process for recovering qualified stable light hydrocarbons in the flash stabilization process. Background Technology

[0002] During crude oil processing, the pressure of the upstream oil-gas separator in the atmospheric pressure tank is higher than atmospheric pressure, resulting in the presence of a large amount of C1-C4 components with low boiling points, high vapor pressures, and high volatility. When the processed crude oil enters the field storage tank and the pressure drops to atmospheric pressure, these highly volatile components flash out of the crude oil, carrying away the heavier components through the carryover effect, causing evaporation losses. Generally, this loss can reach 1% to 2% of the total crude oil volume. Therefore, before entering the storage tank after processing, the crude oil is stabilized to reduce its saturated vapor pressure. The main products of crude oil stabilization are stabilized crude oil, stabilized gas (i.e., natural gas), and light oil.

[0003] Crude oil stabilization processes are mainly divided into flash distillation and fractionation. For ordinary crude oil, flash distillation is the superior process, with advantages such as low energy consumption, fewer equipment requirements, and lower investment. However, because flash distillation cannot effectively separate the gaseous components in crude oil, its volatile gas phase contains a large amount of heavy components. Ultimately, this results in the heavy components in the light oil product not meeting the specifications. The national standard GB 9053-2013 "Stabilized Light Hydrocarbons" stipulates that the final boiling point of No. I stabilized light hydrocarbons should not exceed 190℃. Due to the substandard final boiling point caused by the heavy components in the stabilized light hydrocarbons produced by flash distillation stabilization units, the stabilized light hydrocarbon products produced by crude oil stabilization units cannot be sold normally, resulting in certain economic losses.

[0004] CN110538476A - A low-temperature flash evaporation light hydrocarbon recovery system and method for associated gas in oil fields. The recovery system includes a feed gas compressor, a first adsorption tower, a low-temperature heat exchanger, a first-stage flash separator, a second-stage flash separator, an ethane stripper, a ethane stripper reboiler, a liquefied gas tower, a reflux tank, and a liquefied gas tower reboiler. The low-temperature heat exchanger is equipped with channels A, B, C, and D. However, the final boiling point of the stable light hydrocarbon product produced during the flash stabilization process does not meet the standard. Summary of the Invention

[0005] To address the problems associated with flash stabilization, this invention successfully solves the issue of the final boiling point of the stabilized light hydrocarbon product produced during the flash stabilization process not meeting the standard.

[0006] The above-mentioned objective of this invention is achieved through the following technical solution:

[0007] A system for recovering qualified stabilized light hydrocarbons in a flash stabilization process includes a crude oil buffer tank, a flash stabilization tower module, a primary cooling and separation module for stabilized gas, and a secondary flash stabilization and separation module for light oil. In the primary cooling and separation module, one pipe of the stabilized gas cooler is connected to the crude oil stabilization tower in the flash stabilization tower module, and another pipe is connected to the stabilized gas separator in the primary cooling and separation module. One pipe of the stabilized gas separator is connected to the light oil separator, and the other is connected to the outlet B of the booster pump in the flash stabilization tower module. The light oil separator in the secondary flash stabilization and separation module has three main pipes: one connected to the stabilized gas separator, one connected to the wastewater treatment system, and the other connected to the light oil storage tank.

[0008] Furthermore, the pipeline between the crude oil buffer tank and the crude oil stabilization tower is equipped with at least one booster pump A.

[0009] Furthermore, at least one booster pump B is installed in the pipeline between the bottom of the crude oil stabilization tower and the storage tank.

[0010] Furthermore, at least one booster pump C shall be installed in the pipeline connecting the stabilized gas separator and the outlet pipeline of the booster pump B at the bottom of the crude oil stabilizer tower.

[0011] Furthermore, the pipeline connecting the light oil separator and the light oil storage tank is equipped with at least one booster pump D.

[0012] Furthermore, a three-phase separator is selected for the light oil separator.

[0013] A process for recovering qualified stabilized light hydrocarbons in a flash stabilization process: Crude oil enters a crude oil buffer tank for buffering. The crude oil from the buffer tank is pressurized by booster pump A and transported to the crude oil stabilization tower for flash evaporation, or it enters the crude oil stabilization tower under its own pressure. The crude oil at the bottom of the crude oil stabilization tower is pressurized by booster pump B and then transported for storage. The flash gas at the top of the crude oil stabilization tower is cooled by a stabilizer gas cooler and enters a stabilizer gas separator for primary separation. The separated liquid is pressurized by booster pump C and mixed with the stabilized crude oil for external transport. The separated stabilized gas enters a stabilizer gas compressor for pressurization and cooling for gas-liquid separation. The gas is transported as stabilized gas, and the liquid enters a light oil separator for secondary flash evaporation and three-phase separation of oil, gas, and water. The light oil separator is pressure controlled. The gas phase is connected to the stabilizer gas separator to control the pressure. The liquid phase is the qualified stabilized light hydrocarbon product, which is pressurized by booster pump D and then stored in a light oil storage tank. The water phase is pumped to a wastewater treatment system as oily wastewater.

[0014] Furthermore, the operating pressure of the crude oil buffer tank is 0.2 to 0.5 MPa (A), and the oil inlet temperature is controlled at 60 to 100℃.

[0015] Furthermore, booster pump A pressurizes the pressure to 0.3–0.5 MPa (A).

[0016] Furthermore, the flash pressure is divided into negative pressure (50-70 kPa(A)) or positive pressure (0.1-0.12 MPa(A)).

[0017] Furthermore, booster pump B pressurizes the pressure to 0.3–0.5 MPa (A).

[0018] Furthermore, the temperature of the primary cooling stage is controlled between 40 and 60°C.

[0019] Furthermore, the stabilizing gas compressor pressurizes the gas to 0.3–0.4 MPa (A).

[0020] Furthermore, the pressure of the light oil separator is controlled at 0.1–0.15 MPa (A).

[0021] Furthermore, the booster pump D pressurizes the pressure to 0.3MPa~0.4MPa(A).

[0022] This process mainly employs primary cooling separation and secondary flash evaporation separation, which offers the following advantages compared to existing technologies:

[0023] 1. Through primary cooling separation, heavy components that affect the final boiling point of stable light hydrocarbons are separated. By adjusting the primary cooling process, the separation effect of heavy components can be well controlled.

[0024] 2. Through two-stage flash evaporation, the saturated vapor pressure of stable light hydrocarbons is controlled below 0.2 MPa, meeting the relevant specifications for the saturated vapor pressure of stable light hydrocarbons. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] Figure 1 This is a schematic diagram of the crude oil buffer tank process structure, which mainly ensures the stability of crude oil entering the stabilization tower;

[0027] Figure 2 This is a schematic diagram of the flash stabilization tower process, which realizes the stabilization of crude oil. The product at the bottom of the tower is the stabilized crude oil, and the gas phase enters the first-stage cooling and separation of the stabilized gas.

[0028] Figure 3 This is a schematic diagram of the primary cooling and separation process for stabilized gas, which achieves the separation of heavy components in the stabilized gas that affect the final boiling point of the stabilized light hydrocarbon products.

[0029] Figure 4 This is a schematic diagram of a secondary flash evaporation separation process for light oil, used to control and stabilize the saturated vapor pressure of light hydrocarbons and achieve three-phase separation of oil, gas, and water.

[0030] Among them, 1. crude oil buffer tank; 2. booster pump A; 3. crude oil stabilizer tower; 4. booster pump B; 5. stabilizer gas cooler; 6. stabilizer gas separator; 7. booster pump C; 8. light oil separator; 9. booster pump D. Detailed Implementation

[0031] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0032] Example 1

[0033] The system includes a crude oil buffer tank 1, a flash stabilization tower module, a primary cooling and separation module for stabilized gas, and a secondary flash evaporation and separation module for light oil. In the primary cooling and separation module for stabilized gas, one pipe of the stabilized gas cooler 5 is connected to the crude oil stabilizer 3 in the flash stabilization tower module, and the other pipe is connected to the stabilized gas separator 5 in the primary cooling and separation module for stabilized gas. One pipe of the stabilized gas separator 5 is connected to the light oil separator 8, and the other pipe is connected to the outlet of the booster pump B4 in the flash stabilization tower module. In the secondary flash evaporation and separation module for light oil, the light oil separator 8 is equipped with three main pipes: one is connected to the stabilized gas separator 6, one is connected to the wastewater treatment system, and the other is connected to the light oil storage tank.

[0034] The process includes the following steps:

[0035] 1. Crude oil comes from the crude oil processing unit and enters the crude oil buffer tank 1 for buffering. The operating pressure of crude oil buffer tank 1 is 0.2-0.5 MPa (A), and the oil temperature is controlled at 60-100℃.

[0036] 2. The crude oil coming out of crude oil buffer tank 1 can be either pressurized to 0.3-0.5MPa (A) by booster pump A2 and transported to crude oil stabilizer 3, or it can enter crude oil stabilizer 3 by its own pressure, depending on the operating pressure.

[0037] 3. Crude oil enters crude oil stabilization tower 3 and undergoes flash evaporation within it. The flash evaporation pressure can be either negative (50–70 kPa(A)) or positive (0.1–0.12 MPa). The crude oil at the bottom of the tower is pressurized to 0.3–0.5 MPa(A) by booster pump B4 before being transported for storage.

[0038] 4. The flash gas at the top of the tower undergoes primary cooling, with the cooling temperature controlled between 40 and 60°C depending on the composition. After cooling, the medium enters the stabilized gas separator 6 for primary separation. The separated liquid and stabilized crude oil are pressurized by a pump and then mixed with the stabilized crude oil for external transportation.

[0039] 5. The separated stabilized gas enters the stabilized gas compressor and is pressurized to 0.3-0.4 MPa(A), then cooled to 40°C, and further separated by a gas-liquid separator. The gas phase is exported as stabilized gas. The liquid phase enters the light oil separator 8 for secondary flash evaporation and three-phase separation of oil, gas, and water.

[0040] 6. The light oil separator 8 is pressure controlled, with the pressure kept below 0.2 MPa (A). The gas phase is connected to the flash stabilizer 6 to control the pressure. The liquid phase is the qualified stabilized light hydrocarbon product, which is pressurized to 0.3 MPa to 0.4 MPa (A) by the booster pump D9 and then enters the light oil storage tank for storage. The aqueous phase is pumped to the wastewater treatment system as oily wastewater.

[0041] Example 2

[0042] The development of this technology was based on the construction project of a crude oil stabilization unit at the Shenyang Oil Production Plant of Liaohe Oilfield Company. Currently, one crude oil stabilization unit has been completed, with an annual processing capacity of 1 million tons of crude oil. By adopting the technical solution of this invention, this project can produce 7,500 tons of qualified stabilized light hydrocarbons annually, achieving economic benefits of over 30 million yuan.

[0043] Given that the crude oil flash stabilization process is widely used in crude oil processing, this technology can produce qualified stable light hydrocarbons through flash stabilization, and therefore has good application prospects.

[0044] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A system for recovering qualified stabilized light hydrocarbons in a flash stabilization process, characterized in that, The system includes a crude oil buffer tank (1), a flash stabilization tower module, a primary cooling and separation module for stabilized gas, and a secondary flash evaporation and separation module for light oil. In the primary cooling and separation module for stabilized gas, one pipe of the stabilized gas cooler (5) is connected to the crude oil stabilizer (3) in the flash stabilization tower module, and the other pipe is connected to the stabilized gas separator (5) in the primary cooling and separation module for stabilized gas. One pipe of the stabilized gas separator (5) is connected to the light oil separator (8), and the other pipe is connected to the outlet of the booster pump B (4) in the flash stabilization tower module. In the secondary flash evaporation and separation module for light oil, the light oil separator (8) is equipped with three main pipes: one is connected to the stabilized gas separator (6), one is connected to the sewage treatment system, and the other is connected to the light oil storage tank.

2. The system for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 1, characterized in that, The pipeline between the crude oil buffer tank (1) and the crude oil stabilizer tower (3) is equipped with at least one booster pump A (2).

3. The system for recovering qualified stable light hydrocarbons in the flash stabilization process according to claim 1, characterized in that, the stabilization... At least one booster pump C (7) shall be installed between the gas separator (6) and the outlet pipeline of the booster pump B (4) at the bottom of the crude oil stabilizer (3).

4. The system for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 1, characterized in that, The pipeline connecting the light oil separator (8) to the light oil storage tank is equipped with at least one booster pump D (9).

5. The system for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 1, characterized in that, The light oil separator (8) is a three-phase separator.

6. A process for recovering qualified stabilized light hydrocarbons in a flash stabilization process, characterized in that, Crude oil enters the crude oil buffer tank (1) for buffering. The crude oil coming out of the crude oil buffer tank (1) is pressurized by the booster pump A (2) and transported to the crude oil stabilizer tower (3) for flash evaporation, or it enters the crude oil stabilizer tower (3) by gravity. The crude oil at the bottom of the crude oil stabilizer tower (3) is pressurized by the booster pump B (4) and then transported for storage. The flash gas at the top of the crude oil stabilizer tower (3) is cooled by the stabilizer gas cooler (5) and enters the stabilizer gas separator (6) for primary separation. The separated liquid is pressurized by the booster pump C (7) and then mixed with... The stable crude oil mixture is transported out, and the separated stable gas enters the stable gas compressor for pressurization and cooling for gas-liquid separation. The gas is transported out as stable gas, and the liquid enters the light oil separator (8) for secondary flash evaporation and three-phase separation of oil, gas and water. The light oil separator (8) is pressure controlled. The gas phase is connected to the stable gas separator (6) to control the pressure. The liquid phase is the qualified stable light hydrocarbon product. After being pressurized by the booster pump D (9), it enters the light oil storage tank for storage. The water phase is transported to the sewage treatment system as oily wastewater by a pump.

7. The process for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 5, characterized in that, The crude oil buffer tank (2) operates at a pressure of 0.2 to 0.5 MPa (A) and the oil temperature is controlled at 60 to 100℃.

8. The process for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 5, characterized in that, Booster pump A(2) pressurizes to 0.3-0.5MPa (A).

9. The process for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 5, characterized in that, Flash pressure is divided into negative pressure (50-70 kPa(A)) or positive pressure (0.1-0.12 MPa(A)).

10. The process for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 5, characterized in that, Booster pump B(4) pressurizes to 0.3-0.5MPa(A).

11. The process for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 5, characterized in that, The temperature of the primary cooling stage is controlled at 40–60°C (A).

12. The process for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 5, characterized in that, The stabilizer gas compressor pressurizes the gas to 0.3–0.4 MPa (A).

13. The process for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 5, characterized in that, The pressure of the light oil separator (8) is controlled at 0.1 to 0.15 MPa (A).

14. The process for recovering qualified stabilized light hydrocarbons in the flash stabilization process according to claim 5, characterized in that, The booster pump D(9) pressurizes the pressure to 0.3MPa~0.4MPa(A).

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