In crude oil processing, an electrostatic heater-treater is used to separate water and hydrocarbons. The electrostatic grid's primary function is to apply an electric field that helps promote the coalescence (or merging) of small water droplets into larger droplets, which then separate from the oil more easily. This improves the efficiency of the separation process.
- Option (A) is incorrect because separating sand particles is not the main role of the electrostatic grid in this context.
- Option (C) is incorrect as the electrostatic grid does not generate electrical energy from the kinetic energy of the feed.
- Option (D) is not the primary function of the electrostatic grid, which is more concerned with separating water droplets from oil.
Therefore, the correct answer is option (B).