Deep desalting method and deep desalting device for crude oil
By using solid adsorbents such as molecular sieves to deeply dehydrate crude oil after electro-desalting, the problem of the difficulty in further reducing the salt content of crude oil in existing technologies has been solved, achieving deep desalting of crude oil and reducing the corrosion risk of refining units.
Patent Information
- Application Number
- CN202410671424.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-28
- Publication Date
- 2025-11-28
AI Technical Summary
Existing electro-desalting technology is insufficient to further reduce the salt content in crude oil, making it difficult to alleviate corrosion problems in subsequent refining units.
Solid adsorbents such as molecular sieves, activated carbon, or silica gel are used to deeply dehydrate residual water in crude oil after electro-desalting. Deep desalting is achieved through an adsorption tank. After the adsorbent is saturated, it is washed with water and regenerated by heating for reuse.
It effectively reduces the salt content in crude oil to less than 1 mg NaCl/L and the water content to less than 0.1 wt.%, mitigating the corrosion risk of subsequent refining units.
Smart Images
Figure CN121022452A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of crude oil desalting technology, specifically to a deep desalting method and apparatus for crude oil. Background Technology
[0002] Crude oil desalting is the first step in crude oil processing, aiming to remove salts, primarily chlorides, from crude oil to mitigate corrosion of equipment caused by chlorine during processing. Current refining processes mainly employ electro-desalting technology, resulting in numerous mature technologies and equipment, such as AC desalting, AC / DC desalting, and high-speed electro-desalting. For most crude oils, current electro-desalting technology can generally achieve processing requirements of less than 3 mg NaCl / L and less than 0.3 wt.% water content after desalting. However, under current electro-desalting technology and operating conditions, it is difficult to further reduce the salt content after desalting, which is detrimental to further mitigating corrosion in subsequent refining units. Summary of the Invention
[0003] The present invention aims to provide a deep desalting method and apparatus for crude oil, which further reduces the salt content in crude oil after electro-desalting in the prior art.
[0004] To solve the above technical problems, the specific solution adopted by the present invention is as follows: a deep desalting method for crude oil, which uses a solid adsorbent to adsorb the residual water in the crude oil after electro-desalting, so as to remove the salt dissolved in the residual water.
[0005] Preferably, the desalted crude oil is passed into an adsorption tank equipped with a solid adsorbent, where the solid adsorbent adsorbs the residual water in the desalted crude oil.
[0006] Preferably, the operating temperature in the adsorption tank is 70-180℃.
[0007] Preferably, the liquid operating space velocity of the adsorption tank is 0.2-5 h⁻¹. -1 .
[0008] Preferably, the liquid operating space velocity of the adsorption tank is 0.5-1.5 h⁻¹. -1 .
[0009] Preferably, the number of adsorption tanks is set to multiple, with one tank in operation and one in standby, or one tank in operation and multiple in standby.
[0010] Preferably, the solid adsorbent is treated as solid waste after adsorption saturation, or it is regenerated and reused after washing, heating and drying.
[0011] Preferably, the solid adsorbent is any one of molecular sieve, activated carbon, and silica gel.
[0012] Preferably, the molecular sieve is a 3A molecular sieve or a 13X molecular sieve.
[0013] A crude oil deep desalting device includes an adsorption tank, which can hold a solid adsorbent for adsorbing residual water in crude oil after electro-desalting. The adsorption tank is also provided with an inlet for the crude oil after electro-desalting to enter and an outlet for the crude oil after desalting to exit.
[0014] Preferably, the adsorption tank is also connected to a backwash water injection regeneration gas pipeline.
[0015] Preferably, the number of adsorption tanks is set to multiple, with one tank in operation and one in standby, or one tank in operation and multiple in standby.
[0016] The applicant's research revealed that a key reason why conventional electro-desalting treatment struggles to further reduce the salt content of crude oil (e.g., to achieve a salt content of less than 2 mg NaCl / L) is that the crude oil still contains approximately 0.3 wt.% residual water after electro-desalting. This residual water dissolves inorganic salts, further hindering the reduction of the salt content. This invention utilizes a solid adsorbent for deep dehydration of the electro-desalted crude oil, thereby further reducing the salt content and achieving deep desalting. This is of great significance for mitigating corrosion in subsequent refining units.
[0017] The crude oil deep desalting process of this invention is convenient to operate, highly effective, and suitable for long-term operation. It is effective for various types of crude oil, especially for devices where the high water / salt content of crude oil after electro-desalting makes desalting difficult. This process can further reduce the salt content of the crude oil after desalting. After treatment with this device, the crude oil can achieve a salt content of less than 1 mg NaCl / L and a water content of less than 0.1 wt.%, compared to the existing electro-desalting process where the crude oil has a salt content of about 3 mg NaCl / L and a water content of about 0.3 wt.%, thereby further mitigating the corrosion of subsequent processing equipment caused by chlorine in the crude oil. Attached Figure Description
[0018] Figure 1 This is a process flow diagram of a deep desalting method for crude oil according to the present invention. Detailed Implementation
[0019] This invention relates to a deep desalting process for crude oil. The desalting mechanism involves using a solid adsorbent with water-absorbing properties to remove residual water from the crude oil after electro-desalting, thereby further removing salt from the crude oil. Specifically, the electro-desalted crude oil is passed into an adsorption tank containing a solid adsorbent for deep dehydration and desalting. After the adsorbent becomes saturated, it is regenerated through water washing, heating, and drying. The process flow is as follows: Figure 1 As shown:
[0020] Crude oil after electro-desalting refers to crude oil that has been processed by a conventional electro-desalting unit, and generally meets the processing requirements of salt content less than 3 mg NaCl / L and water content less than 0.3 wt.%.
[0021] The solid adsorbent is a porous water-absorbing material such as water-absorbing molecular sieve, activated carbon, and silica gel, preferably a molecular sieve, and most preferably a 3A molecular sieve and a 13X molecular sieve.
[0022] Multiple adsorption tanks are configured to ensure operational efficiency by allowing one tank to be operational while another is on standby, or vice versa, facilitating inspection, regeneration, or other maintenance. The adsorption operating temperature within the tanks is maintained between 70-180°C, ideally matching the temperature of the crude oil after electro-desalting. The liquid hourly space velocity (LHSV) of the adsorption tanks is 0.2-5 h⁻¹. -1 Preferably, it is 0.5-1.5h. -1 During regeneration, the adsorption tank is first washed with demineralized water, then purged with gas. The regeneration carrier gas includes steam, air, and nitrogen, preferably air. The operating temperature for regeneration of the adsorption tank is 100-300℃, preferably 150-200℃.
[0023] The present invention will be further illustrated by the following three embodiments:
[0024] Select a density of 0.9335 g / cm³. 3 A deep desalting test was conducted on crude oil with a salt content of 5 mg NaCl / L and a water content of 0.48 wt.% after electro-desalting treatment. The adsorption tank operating conditions were: the adsorption tank was filled with 3A molecular sieve, the operating temperature was 145℃, and the liquid hourly space velocity was 1 h⁻¹. -1 After the adsorbent becomes saturated, it is first rinsed with demineralized water, and then purged with 180℃ hot N2. After more than 10 adsorption-regeneration cycles, the crude oil after adsorption treatment in the adsorption tank has a salt content of 0.6 mg NaCl / L and a water content of 0.14 wt.%.
[0025] Example 2
[0026] Select a density of 0.8735 g / cm³ 3 A deep desalting test was conducted on crude oil with a salt content of 2.5 mg NaCl / L and a water content of 0.27 wt.% after electro-desalting treatment. The operating conditions of the adsorption tank were: the adsorption tank was filled with 3A molecular sieve, the operating temperature of the adsorption tank was 135℃, and the liquid hourly space velocity was 2 h⁻¹. -1 After the adsorbent becomes saturated, it is first rinsed with demineralized water, and then purged with 180℃ hot N2. After more than 10 adsorption-regeneration cycles, the crude oil after adsorption treatment in the adsorption tank has a salt content of 0.6 mg NaCl / L and a water content of 0.07 wt.%.
[0027] Example 3
[0028] A density of 0.8921 g / cm³ was selected. 3 A deep desalting test was conducted on crude oil with a salt content of 3.1 mg NaCl / L and a water content of 0.37 wt.% after electro-desalting treatment. The operating conditions of the adsorption tank were: the adsorption tank was filled with 3A molecular sieve, the operating temperature was 140℃, and the liquid hourly space velocity was 1.5 h⁻¹. -1 After the adsorbent becomes saturated, it is first rinsed with demineralized water, and then purged with 180℃ hot N2. After more than 10 adsorption-regeneration cycles, the crude oil after adsorption treatment in the adsorption tank has a salt content of 0.8 mg NaCl / L and a water content of 0.08 wt.%.
Claims
1. A method for deep desalting crude oil, characterized in that: Solid adsorbents are used to adsorb residual water in crude oil after electro-desalting in order to remove the salt dissolved in the residual water.
2. The crude oil deep desalting method as described in claim 1, characterized in that: The desalted crude oil is passed into an adsorption tank equipped with a solid adsorbent, which adsorbs the residual water in the desalted crude oil.
3. The crude oil deep desalting method as described in claim 2, characterized in that: The operating temperature in the adsorption tank is 70-180℃.
4. The crude oil deep desalting method as described in claim 2, characterized in that: The liquid operating space velocity of the adsorption tank is 0.2-5 h⁻¹. -1 .
5. The crude oil deep desalting method as described in claim 4, characterized in that: The liquid hourly space velocity (LHSV) of the adsorption tank is 0.5-1.5 h⁻¹. -1 .
6. The crude oil deep desalting method as described in claim 2, characterized in that: The number of adsorption tanks can be set to one in operation and one in standby or one in operation and multiple in standby.
7. The crude oil deep desalting method as described in claim 1, characterized in that: After the solid adsorbent becomes saturated, it is treated as solid waste, or it can be regenerated and reused after being washed, heated and dried.
8. The crude oil deep desalting method as described in claim 1, characterized in that: The solid adsorbent is any one of molecular sieve, activated carbon, and silica gel.
9. The crude oil deep desalting method as described in claim 8, characterized in that: The molecular sieve is either 3A molecular sieve or 13X molecular sieve.
10. A crude oil deep desalting device, characterized in that: It includes an adsorption tank, which can hold a solid adsorbent for adsorbing residual water in crude oil after electro-desalting. The adsorption tank is also equipped with an inlet for the crude oil to enter after electro-desalting and an outlet for the crude oil to exit after desalting.
11. A crude oil deep desalting device as described in claim 10, characterized in that: The adsorption tank is also connected to a backwash water injection regeneration gas pipeline.
12. The crude oil deep desalting device as described in claim 10, characterized in that: The number of adsorption tanks can be set to one in operation and one in standby or one in operation and multiple in standby.