The purpose ofthe oil processing unit is to provide free water removal and coalescence ofentrained water particles to allow the oil to meet pipeline specifications forthat area in which the unit is recommended and installed.
Hetaer treater usesmethod of heating, chemical action, electrical coalescing and settling forde-emulsifications of oil. All heater treaters utilize the law of gravity toseparate the lighter from the heavier components; gas is the lightest, oil isnext, then water. The plant has 6 no of heater treatersand 2 bath heaters with overall annual consumption of about ____ scm Natural gaswhich constitutes of about ____ INR annually.
Bath heaters are use to preheat theemulsion to ease the mixing and initiation of the de-emulsifying agent. Heatedliquid is treated in heater treater to reduce water content. Crude oil withtraces of water is dispatched to Mehsana CTF plant for further treatment tomeet the specifications of refinery and effluent with traces of oil is sent toETP where remaining oil is scavenged and water is re pumped into earth forfilling up the space thus created.Heater treaterconsists of four parts for performing the demulsification process:1.
Inlet degassing section: Theproduced fluid enters the processing unit above the fire tubes in the inletdegassing section. Free gas is librated from the flow stream and is equalizedacross the entire degassing and heating areas of the heater treater. Degassingsection is separated from the heating section by baffles. The fluid travelsdownward from degassing area and enters the heating section.2.
Heating section: Heater treater consists of 2 fire tubeswhich are connected to burners. These fire tubes should be immersed in liquidwhen the burners are in operation to avoid any damage to the fire tubes due toexcessive 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 burnerswhenever the liquid level goes below the fire tubes and switches on the gassupply when the liquid level rises above the fire tubes. The desiredtemperature is maintained in heater treater by automatic temperaturecontroller. 3.
Mechanical section:The clean effluentwater discharge valve controller float is fitted in this chamber. This floatactivates the dump control valve whenever the liquid rises above the levelsetting. The gas pressure in the inlet and heating sections of the vessel isutilized to move the fluid from the mechanical section into the coalescingsection 4. Coalescing section (Electrical section) Electrical heater treater uses highvoltage potential on electrodes for coalescing of water droplets in the finalphase.
Liquid enters this chamber through a distributor tube. As the emulsion passes through theelectrical field the water droplets in the emulsion become electrically chargedand they move about rapidly and collide with one another. As they collide thedroplets grow in size forming larger droplets, until they become large enoughto settle. There are two grids in this chamber which are connected to atransformer which provides 440volts supply. One grid is connected to +Ve andanother one is to –Ve which is the body of vessel In this chamber constantlevel of water is maintained so that the oil coming from the previous chamberis washed before proceeding upwards, so in case there in free water droplets,they will settle. The interface float is connected to the water discharge valveby means of a pneumatic signal.
The Clean oil continues to rise to the top ofthis chamber, where it enters a collector and is discharged through the cleanoil outlet control valve.