Horizontal heater-treaters controller

Equation (4.15) should be considered the final oil-treatment stage, in which a 0.5 to 1% water cut in treated oil is produced. Here a heater-treater-type horizontal vessel is more commonly used. A direct-fired burner-heater is normally placed in a front section of the horizontal treater. Controlling the system temperature for viscosity is important and may be mandatory for successful water dehydration. 

Vertical treaters have a much lower volume-to-throughput ratio than gun barrels. As a result, more complete treatment is necessary in a shorter time. Solids control is as important as interface control, just as with the horizontal treater. Figure 5 illustrates a schematic of a vertical heater treater that also employs a dual-polarity electrostatic grid to effect more efficient coalescence and thereby better oil-water separation. 

Heaters are vessels used to raise the temperature of the liquid before it enters a gunbarrel, wash tank, or horizontal flow treater. They are used to treat crude oil emulsions. The two types of heaters commonly used in upstream operations are indirect fired heaters and direct fired heaters. Both types have a shell and a fire tube. Indirect heaters have a third element, which is the process flow coil. Heaters have standard accessories such as burners, regulators, relief valves, thermometers, temperature controllers, etc. 

The electrostatic separator shown in Fig. 4.2 is normally placed in stream 6, shown in Fig. 4.1. A heater should be installed upstream of this electrostatic treater to control temperature. Here heating temperatures should normally range from 100 to 200°F for light crudes 22°API and above. For heavier crudes, use higher temperatures, such as 250°F for a 14°API crude oil. Some heavier crudes, below 14°API, may require temperatures up to 300°F for adequate electrostatic dehydration. This temperature is to achieve a gravity difference between the crude oil and water of 0.001 or more. The electric power required by these electrogrids is normally 0.05 to 0.10 kVA/ft2. The ft2 area is the horizontal cross-section area in the electric grid section of the electrostatic dehydrator. 

---