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LEARN FROM OUR EXPERTS about how to increase reliability and profitability in the delayed coking unit with continuous level measurement. Our top minds will take you through finding solutions to the challenges faced when measuring level in a coke drum.

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Measuring the level and level switch of coke in coke drums

The delayed coker is the only semi-continuous batch process in the refinery, which means that the feed is continuously switched between two drums in a time-based cycle. The fresh feed, usually from the vacuum tower bottoms, is fed to the bottom of the coker fractionation tower to help pre-heat the feed and mixed with the bottom hydrocarbons. This mixture is then passed to the heater to apply the energy required to thermally crack the large hydrocarbon chains. After that the heated resid is pumped to large drums to allow for the cracking and expansion of the fluids, whereby the lighter cracked hydrocarbons are taken off the top of the drums to the fractionation tower. As the heavy hydrocarbons are cracked, the resulting hydrocarbons are then converted into a vapour due to the high temperature. As the vapours escape the viscous liquid, they tend to create a foam layer. This foam layer can vary depending on many parameters such as operating temperature, pressure of the drum, type of crude, charging rate etc. 

Measuring the level of bottom liquids in the fractionator

Monitoring the level of bottoms liquids in a delayed coker is among the most important processes in a refinery. Due to the conditions in the coke drum and fractionator, a level measurement is a very challenging task. Where other measuring technologies tend to fail or end up being extremely unreliable, Berthold‘s radiometric level technology is ideal for monitoring the coke level due to its non-intrusive nature. Since large temperature variations through the whole operational cycle of a coke drum are a known issue to the operators, our patented automatic stabilization technology based on cosmic radiation has proven to be the most important feature to guarantee a stable and reliable level measurement without the need for recalibration. Separate level alarms ensure additional process safety. The same applies for the fractionator. Our level gauges are used to monitor the bottom liquid level – an important parameter for the efficient control of the complete coking cycle. A big advantage is that measurement is unaffected by surface turbulences, product falling down from the trays, different product densities, or scaling/coking.

Customer Benefit

  • Reliable level control
  • Improved utilization of drum capacity
  • Efficient use of anti-foam agent
  • Increased throughput, process safety and reliability
  • Safety prevents from liquid carry-over into the vapor inlets
  • Ensures minimum liquid head for the coker charge pump

Characteristics

  • Non-contacting, non-intrusive level measurement
  • Use of 8 m long TowerSENS detectors (covering up to 32 m in cascaded mode)
  • Highest sensitivity due to solid scintillators leading to significantly lower source activities
  • High repeatability and long-term stability
  • Minimizes NDT interference with internal proprietary algorithms

SIL certification available

The SENSseries LB 480 detectors are certified for use in SIL2 applications. Even SIL3 is achieved with homogenous redundancy. The certificate covers all measurement applications, from high level or low level alarms to continuous level measurement and density measurement. Thus safe operation of critical oil and gas processes is guaranteed.

More about SIL

 

Long-term stability

A reliable measurement is vital for the operation of a process and is therefore, our highest priority. Berthold’s detectors operate absolutely stable irrespective of changes in ambient temperature. Even drastic temperature shifts, e.g. from winter to summer don’t irritate the measurement drift. Our patented method for detector stabilization compensates for temperature influences and aging.

Detector Stability

Gas Property Compensation (GPC)

In the case of radiometric measurement, this can falsify the measured value, unless you have gas density compensation compensation from Berthold. With the feature GPC, a second measurement determines the current gas density in the tank and has a compensating effect on the connected continuous level measurement. 

More about GPC

We help you to optimize your processes

A foam over in a delayed coker unit can be a costly event, not only causing loss of production but also requiring a lot of manual labour to clean coke out of the overhead lines and factionation tower. In order to increase throughput of the unit, one of the most important objective is to safely and reliably fill the drum higher, however, to achieve this, one must have a reliable measurement method for the foam front in the drums.
Due to the conditions in the coke drum, a level measurement is a very challenging task. Where other measuring technologies tend to fail or end up being extremely unreliable, Berthold‘s radiometric level technology is ideal for monitoring the coke level due to its non-intrusive nature. Since large temperature variations through the whole operational cycle of a coke drum are a known issue to the operators, our patented automatic stabilization technology based on cosmic radiation has proven to be the most important feature to guarantee a stable and reliable level measurement without the need for recalibration. Separate level alarms ensure additional process safety. The same applies for the fractionator. Our level gauges are used to monitor the bottom liquid level – an important parameter for the efficient control of the complete coking cycle. A big advantage is that measurement is unaffected by surface turbulences, product falling down from the trays, different product densities, or scaling/coking.

DOWNLOADS

Level measurement in delayed coking units Application flyer

English | PDF | 724.9 KB

Continuous Level Measurement Product brochure

English | PDF | 4.9 MB

TowerSENS detector for the best solution

TowerSENS Detector

With a max. length of 8 m - the rod detector is specifically designed to monitor long measuring ranges