A heater treater receives the production stream after it leaves the Free Water Knockout during the Oil Production Process, uses heat and retention time to separate the oil from the water. The heat allows for easier separation of the oil and water and also allows solid particles such as sand and corrosion products to settle out of the process. The quality of the oil is measured with a bulk sediment and water probe.

Direct Fired Heater Treater. This style of design allows the fire tube to stay totally submerged within the production fluids. This is called being fluid packed.
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Advantages Disadvantages
  1. For heavier crudes (API Gravity 10 and below), where the density of the oil is near the density of water, heating the emulsion causes the density difference between the oil and water which promotes separation.
  2. Applying heat causes the viscosity of the continuous oil phase and increases the rate the remaining water settles out of the oil.
  3. Convection caused by the heating increases the likelihood of remaining water droplets coalescence.
  4. Currents caused by the heating can assist in the distribution of chemicals used to help with separation.
  5. Keeping the temperature above the cloud point keeps the paraffins from solidifying.
  1. Heating causes the lighter, more volatile to vaporize out of the crude oil into the gas phase. This is disadvantageous for two reasons. First, this can result in a perceived volume loss when the light ends evaporate from the fluid and will result in an API Gravity Reduction & volume shrinkage. Secondly, a gas blanket consisting of volatile hydrocarbon gasses could form and self ignite if the temperature gets too high.
  2. Unless there are heat or fuel sources readily available, operation of the heater treater can get expensive, especially as fuel costs increase.
  3. Direct fired heater treaters are complex pieces of equipment and require instrumentation, controls and safety devices to be installed and working together to ensure a stable safe process. Typical pieces of equipment on a heater treater are dump valves, back pressure valves, temperature and pressure transmitters.

Contents

Types of heater treaters

Heater treaters can be either direct fired or indirect fired or can be horizontal or vertical.

Direct Heater

A direct fired heater treater is designed such that the transfer of heat is accomplished by direct contact of the fluid with the firebox/ fire-tube. Direct fired heater treaters are more efficient than indirect fired heater treaters.

Indirect Heater

An indirect fired heater treater is one where the heating element heats the water or heating medium and the heating medium is then used to transfer heat to the process stream. An indirect fired heater treater would be used if the production stream is sandy. Sand falling out of the emulsion can collect on the fire-tube and cause overheating (hot spots) of the tube. Additionally, if the heater treater is not fluid packed, that is, if gas is being removed from the production stream, there is a likelihood that the top of the fire-tube could be exposed to production gasses and cause an explosion.

Design Considerations

Sand & Sediment

Solid particles such as sand and sediment will separate from the emulsion and will collect at the bottom of the heater treater. Over time, solids accumulation will cause the capacity of the treater to become diminished. Just as importantly, if particulate collects on the fire tubes, it will create hotspots and cause failure of the fire tube.

Vessel design is very important to mitigate issues caused by sand. Water jets can be used in conjunction with sand drains to remove accumulated sand.

Sizing

A heater treater should be designed for a certain amount of residence time. This would be dictated by the API Gravity, inlet temperature, flow rate, emulsion tightness and other design considerations.

Pressure Relief

Ensure that the pressure relief valve does not get plugged up with sand or sediment.

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