Desalting Services

Desalting pilot plant services (units DS1, DS2 and P96)

Process Description:
The purpose of the desalting process is to remove salt and other impurities from crude oil. These salts are normally dissolved in the residual water contained in the crude oil and are difficult to remove by gravity settling. In addition to the salts and water, the other impurities can include silt, iron oxides, sand, crystalline salt, carbon and sulfur. If left unchecked, the salts in crude oil can cause severe downstream problems including corrosion by acids formed by chloride salt decomposition in fractionator overhead equipment, fouling of heat exchangers by salt deposition, and poisoning of catalysts in down-stream units. Typically desalting is the first unit operation in a refinery prior to sending the crude to the distillation train.

Unit Description:
Units DS1 and DS2 are batch desalters with 5 gallon and 20 gallon separation vessels, respectively. These units rely on a chemical additive, temperature (the corresponding pressure) and time to aid the separation and do not employ an electrostatic field. The maximum achievable vessel temperature is 176.7 °C (350.0 °F).

Unit P96 is a continuous two stage, Howe Baker electrostatic desalter. Both stages are vertical as opposed to the horizontal design seen commercially. It can also be operated as a single-stage desalter if desired. By varying the process water injection rate, transformer voltage, chemical additive rate, and operating temperature, the optimum conditions can be determined for any type of crude. The nominal design conditions for unit P96 are as follows:

Additional Attributes to Note:

• Unit P96:
  • Multiple chemical additive injection points are available.
  • The process water used can be local city water, deionized water, or customer provided water.
  • Each desalter vessel includes a series of six trilines that ascend vertically along the side of the vessel to allow for determination and sampling of the oil-water interface.

Analytical Support:

Analytical types and frequency are performed on an as needed basis to ensure that customers are getting only the data they need when they need it. Onsite and external analytical support options are available for characterization and unit control purposes.

In-house analytical support for unit control and external analytical support via the Intertek network of laboratories is as follows:

Common Project Types:
This unit has been used for both the generation of process data and also the production of samples (ranging from several liters to multiple drums) which can include:

• Units DS1 and DS2:
  • Process condition evaluations
  • Chemical additive screening
  • Feedstock screening
• Unit P96:
  • Process condition evaluations
  • Chemical additive screening
  • Feedstock screening
  • Production of drum quantities of desalted crude for subsequent processing either in-house or at a customer facility