Analysis of the reasons for high salt content in crude oil after desalting and adjustment strategies

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In the refining process, the high salt content in the crude oil after desalting is an issue that requires attention, as it can affect subsequent processing steps. Next, let’s analyze in depth the reasons behind it and the methods for adjusting it. I. Cause Analysis 1. Excessively low pressure drop in the mixing valve: The function of the mixing valve is to ensure thorough contact between crude oil and water, so that salts can be more effectively separated from the crude oil. If the pressure drop across the mixing valve is too low, oil and water cannot come into effective contact, and salts cannot be fully dissolved in the water to be carried away, resulting in an increased salt content in the crude oil after desalting. 2. Insufficient water injection: Sufficient water injection is key to ensuring effective desalination. Water can dissolve the salts in crude oil to form brine, which can then be separated through methods such as sedimentation. When the amount of water injected is insufficient, not all of the salts can be dissolved and carried away, resulting in the salt content of the crude oil after dehydration exceeding the specified limit. 3. Too low desalination temperature: Temperature has a significant impact on the desalination process. An appropriate temperature can reduce the viscosity of crude oil, making it easier for oil and water to separate, and also allowing salts to dissolve more easily in water. If the temperature during desalination is too low, the fluidity of the crude oil decreases, resulting in poor separation of oil from water and an elevated salt content in the crude oil after desalination. 4. Increased salt content in crude oil or heavier oil quality: If the salt content in crude oil suddenly increases, or if the oil quality becomes heavier, it will make desalination more difficult. Since the dissolution and separation of salts in heavy crude oil are relatively difficult, the salt content in the crude oil after desalting increases. II. Adjustment methods 1. Appropriately increase the pressure drop across the mixing valve: By adjusting the opening degree of the mixing valve or other related parameters, the pressure drop across it can be increased appropriately, allowing oil and water to come into more thorough contact and facilitating the dissolution and separation of salts. However, be careful not to increase the voltage drop too much, to avoid putting excessive stress on the equipment or increasing energy consumption. 2. Increase the injection volume at stage 1 or stage 2: Based on actual conditions, appropriately increase the injection volume at stage 1 or stage 2 to ensure there is enough water to dissolve the salts in the crude oil. At the same time, attention should be paid to the quality of the water used for injection, to prevent the introduction of other impurities that could affect the desalination efficiency. 3. Increase the crude oil desalination temperature: Within the limits permitted by the equipment and processes, appropriately raise the crude oil desalination temperature. This can be achieved by adjusting the temperature of the heating furnace or other related equipment, but care must be taken to ensure that the temperature is not too high, as this could have an adverse effect on the properties of the crude oil. 4. Contact the relevant departments to stabilize the properties of the crude oil: If an increase in salt content or a change in the quality of the crude oil is detected, it is necessary to contact the production scheduler promptly to find out the origin of the crude oil and any changes in its properties. This will help to stabilize these properties and reduce the impact of such variations on the desalination process.