Delayed coker automation · drum switch sequencing · hydraulic cutting control
Control
Delayed coking is one of the most hazardous operations in refinery service. The decoking cycle, draining and cooling the coke drum, opening the drum head, hydraulically cutting the coke, closing the drum, and returning to service, involves high-temperature steam, high-pressure water, heavy rotating equipment, and heavy coke handling in an environment that demands precision and discipline at every step. Automating this sequence does more than improve efficiency, it eliminates the human errors that have caused the most serious decoking accidents in refinery history.
We design decoking control systems that automate the complete coker operating cycle, from feed switching and drum filling to steam stripping, quench sequencing, drum head removal permissives, hydraulic cutting tool control, and return to service. Every step is interlocked against completion of the preceding step, with verification of valve position, temperature, pressure, and equipment status before the sequence advances. The result is a decoking operation that is consistent from cycle to cycle, fully documented in the control system’s event log, and protected against the sequence errors that cause most decoking incidents, developed to IEC 61131-3 so proven strategies deploy on the platform that best fits your lifecycle, with full logic access.
The Problem
The decoking cycle has specific sequence requirements at every step: feed cannot switch to the new drum until the old drum temperature confirms the coke bed has solidified; the drum cannot be opened for cutting until pressure and temperature are within safe limits; the hydraulic cutting tool cannot be lowered until the top unheading device confirms the drum head is clear; and the drum cannot be returned to service until all cutting tool equipment is clear and the drum is confirmed ready. In a manual or semi-manual operation, each of these verifications depends on operator attention and discipline, and under shift-change pressure, production-schedule pressure, or simple fatigue, they can be rushed or skipped.
The consequences are severe. Drum switching before coke solidification can carry liquid over into the fractionator. Opening a drum head before pressure is verified has caused catastrophic hydrocarbon releases and fires. Advancing the cutting cycle before the tool is in position damages the cutting assembly. And thermal cycling from inconsistent quench sequences accelerates coke drum fatigue, the leading cause of drum failure and the multi-million-dollar repairs that follow. Automation does not just prevent accidents; it extends the economic life of the coke drums by delivering consistent thermal cycles every time.
Capabilities
The coke drum switching sequence transfers feed from the full drum to the empty drum through a carefully sequenced operation involving the switch valve, drum inlet valve, steam purge, and fractionator interface. We automate this complete switching sequence with interlocks that verify the receiving drum is pressurized, the inlet and outlet valves are confirmed in position, and the fractionator interface is configured for the new feed path before feed is transferred. Switching time is minimized while all safety verifications are completed.
The drum head opening permissive system verifies that the drum is in a safe condition before authorizing unheading device operation. We implement a drum head permissive logic that confirms drum pressure is at or below the safe unheading pressure, drum temperature at the top head is within limits, the drain valve is confirmed open, and steam connections are confirmed isolated. The permissive is implemented as a hardwired interlock with a dedicated permissive status indicator at the operator interface, not as a software advisory that can be acknowledged and bypassed.
After the drum is full and the feed is switched, the drum is steamed out to strip residual hydrocarbons before water quench begins. We control the steam injection rate, steam temperature, and overhead vapor handling during the stripping phase, with monitoring of drum skin temperature distribution to verify that the drum is stripping uniformly. The transition from steam to water quench is interlocked against completion of the stripping phase criteria, preventing premature water quench that can cause drum shell cracking from differential thermal shock.
The hydraulic cutting tool (drill bit and water jet cutter) requires precise control of tool rotation speed, vertical travel rate, cutting water pressure, and flow rate for effective coke removal. We design the cutting tool control system, including the hydraulic drive control, winch speed and position control, water pump pressure and flow control, and the cutting sequence logic for initial pilot drilling and full-bore cutting passes. Cutting completion verification uses coke bed level tracking and visual camera integration where provided.
The water quench phase requires careful management of quench water flow rate and drum pressure during the transition from steam to water operation. We control the quench water valve position, drum overhead pressure, and drum drain valve operation through the complete quench cycle, from initial water injection through pressure stabilization and temperature reduction to quench completion. The quench cycle sequence is logged with timestamps and temperature distribution data, providing the cycle-by-cycle record required for drum fatigue life management.
Before a drum can be returned to service for the next fill cycle, our control system verifies a complete set of return-to-service conditions: cutting tool retracted and secured, drum head confirmed installed, drain valve confirmed closed, steam lines confirmed connected, and drum pressure testing completed if required. All return-to-service permissives are logged with timestamps and operator identification in the event log, providing the auditable record required for process safety management documentation.
Delayed coke drum thermal cycling fatigue is the primary cause of drum shell cracking and drum replacement. We integrate coke drum skin thermocouple data into the control system and calculate the cumulative thermal cycle history, including the temperature differential between the feed-switch temperature excursion and the quench completion temperature, for comparison against the drum's design fatigue life. This data supports the drum's fitness-for-service assessment and provides the operating record required for insurance and regulatory inspection purposes.
Every step in the decoking sequence, valve actuation, permissive verification, operator acknowledgment, sequence hold, and alarm, is logged with timestamp, operator identity, and sequence step number in the control system's event log. This comprehensive documentation provides the real-time operating record required for process safety management, incident investigation, and the cycle data required for drum fatigue analysis. The event log is exportable in standard formats for import into the facility's process historian and safety management system.
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A MESSAGE FROM JOHN KAZOUR, CEO
To our customers and partners,
For more than 50 years, our team has helped customers keep critical operations running. We built our reputation as Petrotech by taking responsibility for control systems on important rotating machinery.
As more industries came to us with similar challenges across power generation, compression, and hydro applications, our engineering team kept finding ways to solve them. Eventually, the business outgrew the Petrotech name.
We are entering our next chapter as Innova Technologies. The new name reflects the full scope of our work as a rotating machinery control systems specialist. We engineer controls around the machine, deliver complete projects from design through commissioning, and provide support that stays with the problem until it is solved.
Our name is changing, but the people, engineering experience, and commitment behind the work continue. Our responsibility to active projects and installed systems carries forward under the Innova Technologies name. Your current contacts remain the right place to start, and we will communicate directly if an administrative record requires an update.
We appreciate the trust you have placed in us over the decades, and we look forward to continuing that work as Innova Technologies.
CEO, Innova Technologies
