It tests how you apply engineering principles, decision-making, and leadership in real-life problems — not just technical knowledge.
Here’s a model answer tailored to your real context as Head of Facility in a palm oil refinery and solvent extraction plant ๐
๐งพ Model Answer:
Question: “Can you explain a problem you faced in your project and how you solved it?”
๐น 1. Setting the Context (Project Background)
One of the key challenges I faced was during the commissioning phase of our solvent extraction plant expansion project, where we installed a new desolventizer-toaster (DT) system and hexane recovery unit to increase extraction capacity and solvent recovery efficiency.
The system was designed to operate under low vacuum and precise temperature control, to ensure safe operation and minimize solvent loss.
๐น 2. The Problem Identified
During commissioning, we encountered unstable vacuum pressure and high solvent losses at the vapour condenser section.
The recovery efficiency dropped below design — only about 80% recovery compared to the expected 95%.Additionally, we noticed temperature fluctuation in the desolventizer and traces of solvent carryover in meal discharge, which raised serious safety and product quality concerns.
๐น 3. Immediate Actions and Investigation
I immediately formed a small technical task force involving process, mechanical, and instrumentation engineers.
Our first step was to conduct a systematic root cause analysis using engineering tools:
- Process data review (temperature, vacuum trend, solvent flowrate).
- Equipment inspection of condensers, ejectors, and steam traps.
- Leak test using nitrogen pressure on the vapour line.
- P&ID verification to cross-check installation against design drawings.
We discovered two critical issues:
- Undersized steam ejector nozzle, resulting in insufficient vacuum generation.
- Condensate accumulation in the vapour recovery line due to improperly sloped piping, causing partial blockage.
๐น 4. Engineering Solution Implemented
To resolve the problem, I coordinated the following actions:
- Replaced the ejector nozzle with a properly sized unit as per manufacturer’s performance curve to achieve the required suction capacity.
- Modified the vapour line layout by correcting the slope and adding a drain trap at the low point to prevent condensate buildup.
- Updated the P&ID and as-built drawings to reflect these field corrections.
- Revalidated the vacuum and solvent recovery system through a performance test run.
After modification, the system achieved a stable vacuum of -0.85 bar, solvent recovery improved to above 96%, and hexane emission dropped within DOE compliance limits.
๐น 5. Lessons Learned and Preventive Measures
This incident taught our team several lessons:
- The importance of verifying vendor design data and installation drawings before commissioning.
- The need for interdisciplinary reviews — process, mechanical, and instrumentation must work closely during pre-start-up checks.
- Implementing a Pre-Start-Up Safety Review (PSSR) checklist for future projects to identify installation errors before introducing solvent.
Following this, we formalized a Design Review and Commissioning Procedure, which is now mandatory for all future plant modifications.
๐น 6. Concluding Statement
In summary, by applying systematic problem-solving, technical verification, and teamwork, we were able to restore system performance, ensure safe solvent operation, and comply with environmental standards.
As Head of Facility, I see this as an example of how engineering judgement, proactive leadership, and adherence to standards can turn a major commissioning problem into a valuable learning experience for the organization.
๐ง Interview Tip
If interviewer asks a follow-up like:
“What would you do differently next time?”
You can answer:
“I would conduct a more detailed pre-commissioning simulation and vacuum test before introducing solvent, and engage the equipment vendor for on-site performance verification earlier in the process.”
#engineer #ProfessionalEngineer #SteamEngineer
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