The stream and is equalized across the entire

The purpose of
the oil processing unit is to provide free water removal and coalescence of
entrained water particles to allow the oil to meet pipeline specifications for
that area in which the unit is recommended and installed. Hetaer treater uses
method of heating, chemical action, electrical coalescing and settling for
de-emulsifications of oil. All heater treaters utilize the law of gravity to
separate the lighter from the heavier components; gas is the lightest, oil is
next, then water.

The plant has 6 no of heater treaters
and 2 bath heaters with overall annual consumption of about ____ scm Natural gas
which constitutes of about ____ INR annually.

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Bath heaters are use to preheat the
emulsion to ease the mixing and initiation of the de-emulsifying agent. Heated
liquid is treated in heater treater to reduce water content. Crude oil with
traces of water is dispatched to Mehsana CTF plant for further treatment to
meet the specifications of refinery and effluent with traces of oil is sent to
ETP where remaining oil is scavenged and water is re pumped into earth for
filling up the space thus created.

Heater treater
consists of four parts for performing the demulsification process:

1.   
Inlet degassing section:

     The
produced fluid enters the processing unit above the fire tubes in the inlet
degassing section. Free gas is librated from the flow stream and is equalized
across the entire degassing and heating areas of the heater treater. Degassing
section is separated from the heating section by baffles. The fluid travels
downward from degassing area and enters the heating section.

2.   
Heating section:

     Heater treater consists of 2 fire tubes
which are connected to burners. These fire tubes should be immersed in liquid
when the burners are in operation to avoid any damage to the fire tubes due to
excessive heating. This is ensured by micro float fitted above the fire tubes.
The micro float through an ON-OFF switch the cuts off gas supply to burners
whenever the liquid level goes below the fire tubes and switches on the gas
supply when the liquid level rises above the fire tubes. The desired
temperature is maintained in heater treater by automatic temperature
controller.

 

3.   
Mechanical section:

The clean effluent
water discharge valve controller float is fitted in this chamber. This float
activates the dump control valve whenever the liquid rises above the level
setting. The gas pressure in the inlet and heating sections of the vessel is
utilized to move the fluid from the mechanical section into the coalescing
section

 

4.   
Coalescing section (Electrical section)

     Electrical heater treater uses high
voltage potential on electrodes for coalescing of water droplets in the final
phase. Liquid enters this chamber through a distributor tube. As the emulsion passes through the
electrical field the water droplets in the emulsion become electrically charged
and they move about rapidly and collide with one another. As they collide the
droplets grow in size forming larger droplets, until they become large enough
to settle. There are two grids in this chamber which are connected to a
transformer which provides 440volts supply. One grid is connected to +Ve and
another one is to –Ve which is the body of vessel In this chamber constant
level of water is maintained so that the oil coming from the previous chamber
is washed before proceeding upwards, so in case there in free water droplets,
they will settle. The interface float is connected to the water discharge valve
by means of a pneumatic signal. The Clean oil continues to rise to the top of
this chamber, where it enters a collector and is discharged through the clean
oil outlet control valve.