How to increase crude throughput in desalter applications

1. The potential for optimisation

2. Desalting applications today

3. The challenges in desalting applications

4. The limitations in conventional methods

5. Optimise your chemical dosing

6. Increasing crude throughput

7. Conclusion

Summary

The potential for optimisation

Increase crude throughput by as much as 20,000 barrels per day

The potential for optimisation

Deliver savings of up to $3.5m annually in chemical dosing

The potential for optimisation

Deliver savings of up to $330,000 from zero shutdowns

• Within many refineries, there is a growing tendency to process heavier crudes or blend these with lighter feed stocks. During crude oil refining, it is advantageous to optimise the blend to reduce overall feedstock costs whilst at the same time ensuring the final mix can be adequately processed with minimal upset.

• One fundamental need within a refinery process is the efficient separation of wastewater from crude feedstock using a desalter vessel after water washing the material to reduce chloride levels.

• In order to optimise this separation requirement, appropriate vessel and internals design must be used alongside reliable level and interface instrumentation.

Desalting applications today

Hewitt, P. and Vidrine, S. (2006) 9th Topical Conference on Refinery Processing (TA015) – #55 – Advances in Desalting of the 2006 Spring A.I.Ch.E Meeting, Orlando, FL, April 23-27, 2006

Increase use of blended crudes presents calibration challenges for the instrumentation used for level and phase measurement.

High temperature processing of up to 194oC/ 380oFcan mean some instrumentation cannot be used as it will not withstand the extreme temperature.

Gradual build-up on internals affects

measurements thus causing inefficient processing.Keeping the plant operational which is difficult when the emulsion level is not shown.

Challenges in desalting applications

Limitations with conventional methods

Although traditional level and interface measurement systems have their advantages, when applied to the relatively dirty process experienced within a desalter, a number have been found to demonstrate many shortcomings.

Level and interface instruments can be in two categories; mechanical or electrical.

•Mechanical systems such as float have high capital and maintenance costs as well as poor reliability and flexibility.

•Electrical based systems are more popular due to improved reliability and accuracy such as Nucleonic, Capacitive, Guided Wave and DP. Although these still can present problems with the presence of emulsion.

Optimising your chemical dosing

Tracerco ProfilerTM is the only nucleonic instrumentation designed to measure the vertical distribution of oil, emulsion and water in real time at high resolution.

The lynchpin to optimising chemical dosing is repeatable, reliable, accurate measurement.

Optimising your chemical dosing

Confidence in the accuracy of your

instrumentation allows you to run the plant at maximum throughput.

Confidence in the reliability of the ProfilerTM as it

is unaffected by density fluctuations. The same technology is deployed in subsea separation systems.Reliability allows you to continuously monitor the water and oil interface with the additional benefit of

low maintenance cost. The latest version

of the ProfilerTM is designed for temperatures up to 194oC/380oF.

The Tracerco Profiler™ has no moving parts and

therefore gives repeatable measurement.

Optimise your chemical dosing

• Operator confidence to run the interface level at or within the lower electrostatic grid – 82% level.

• Separation optimisation of difficult blends – improve crude flexibility (Escalante crude blend increased from 30kbbl/d to 50kbbl/d).

• Increased upstream desalter mixing to enhance chloride removals from downstream vessels thus reducing corrosion issues (between 3 to 4 ppm to 2ppm).

• Optimisation of chemicals within the desalting process leading to considerable cost savings.

• The elimination of process upsets resulting from water carryover or oil carry under from the desalter vessel.

Case Study Feedback

Chemistry Annual savings

Demulsifier $200,000

Neutraliser $75,000

Water clarifier $130,000

Asphaltene stabiliser

$100,000

No production loss due to desalter

upsets

$330,000

Total Improvement

$835,000

Cost Savings

Increase crude throughput

• With optimised chemical dosing the emulsion level is controlled up to parts per million with the accuracy

delivered by the Profiler’s unique technology allowing more volume in the vessel.

• This volume can be used to process more crude and accuracy of

the measurement gives operator confidence to run the interface level at or within the lower electrostatic grid – 82% level.

• Giving increased throughput of up to 20,000 barrels per day.

Increasing crude throughput

• Controlling the emulsion level is key to increasing crude throughput.

• The more accurately this can be controlled the more volume is available for processing crude.

• This is controlled through accurate phase measurement which allows optimised chemical dosing also saving on chemical costs.

• Where blended crudes are used there is instrumentation available which does not need recalibrating.

• To ensure repeatable, accurate measurement instrumentation needs to have very low failure rates.

• The right instrumentation can deliver huge benefits in increased throughput and cost savings on chemicals.

Conclusion

The Tracerco ProfilerTM delivers all of these things in one instrument.

Conclusion

Controlling emulsion level• Accurate to +/- 1%• It is the only nucleonic

instrumentation designed to measure the vertical distribution of oil, emulsion, water and sand in real time at high resolution.

• Unlike conventional technology, this patented instrument is a 'window' into the vessel to enable the operator to improve production throughput, reduce the number of unscheduled shutdowns and achieve significant cost savings.

No need to recalibrate for blended crudes• Ability to enhance feedstock blend

without the need to re-calibrate equipment with real time process optimisation.

• High stability and accuracy across a wide range of ambient and process temperatures.

Low failure rates – Smart redundancy• 0% failure in service.• SMART redundancy for tubes

mounted at the same elevation, the densities from the two tubes can be averaged.

• Likewise SMART redundancy allows for density values to be calculated via interpolation of the adjacent healthy tube values.

• This ensures minimum interruption to the process.

• No moving parts.• Suitable for temperatures of up to

194oC/380oF.

Conclusion

Conclusion

Benefits – Human Machine Interface (HMI)

• Control from one central location with accurate overview of plant.

• Real time alarms enable quicker reaction in the event of anomalies.

• Real time and historical density and level data is recorded to offer enhanced diagnostics.

• Effective management and operation of instrument and plant.

• Reduced installation cost.

A picture is worth a thousand words.

Conclusion

SpecificationPerformance

Accuracy +/-1% of measurement range

Density Range 0-3000 kg/m3Number of Density Points Over Range

66@500cps, 35@1000cps

Update Interval0.5 seconds to 15 seconds

ElectricalEx-Approvals ATEX Ex ib IIB T4

FM Ex ib C & D Zone 1 Class 1 Div 2

Design Temperature-55°C/67oF to + 194°C/380ºF

Power Galvanic Isolators

CommunicationsEthernet, Modbus TCP/IP, Modbus RTU, 4-20mA

Mechanical

Vessel Nozzle SizeTypically 8"(please enquire as application dependent)

Dip Pipe Casing TitaniumDesign Codes ASME VIII, PD5500

Operating PressureIn accordance with vessel design requirements

Maximum Length Up to 5m

*including ambient temperature factor.

Conclusion

The Tracerco Profiler™ can be used as a control and diagnostic instrument to allow continuous quality monitoring of the water/oil interface.

•Highly reliable and repeatable measurement - 0% failure in service.•Immune to process variations.•No moving parts.•Low cost of ownership.•Live maintenance, no requirement for plant shut down.Single integrated instrument solution providing a multitude of density points to deliver a continuous level & density profile. 

Conclusion

Summary of benefits• Increase crude throughput.• Ability to enhance feedstock blend without the need to re-calibrate

equipment with real time process optimisation.• Eliminate interface excursion upsets and reduce demand on

electrostatic grid power by monitoring rag layer.• High stability and accuracy across a wide range of ambient and

process temperatures.• No radiation dose rate external to the vessel.• Zero maintenance - Annual wipe test required on arming rod

handle.• Reduce maintenance costs and risk to plant by reduced corrosion

risk.• Reduce and optimise chemical processing costs.• Reduce process cost of brine waste treatment by reducing oil

carryover.• Improves asset environmental compliance with less demand on

water treatment.• Smart redundancy.• No risk of damage to instrument under empty vessel conditions.

Find out more

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