Our owner’s engineer services included: tender documentation, award of contract, project management, engineering review, factory inspections and site supervision. We also completed the detailed engineering design of the rainwater and stormwater drain system for the complete site including the adjacent housing colony.
The engines are powered on residual fuel oil (RFO) and operate in a combined cycle arrangement with a total net electrical capacity of 213.60MW at site conditions. The auxiliary plant included for bulk fuel oil storage tanks of 3 x 11,000m3 capacity, fuel unloading station and treatment plant, waste heat boilers supplying steam at 20 and 8 barg, multi-flue stack for exhaust gases, fire protection system, air cooled condenser, fan cooled radiators, water treatment plant, oily water treatment plant, 132kV substation, and all remaining plant and equipment.
Challenges and solutions
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Initial designs for the HFO fuel storage tank heating coils had not allowed for the implications of fouling over the life cycle of the plant, an issue addressed by Tubular Exchanger Manufacturers Association (TEMA). Through theoretical analysis, mathematical analysis and computer simulations, we discovered that the natural convection coefficient within the tanks had been underestimated. By extending the coil lengths, the problem was overcome.
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Powerhouse ventilation was based on a pressurised system which forced atmospheric air into the powerhouse at ground level and was subsequently forced out through outlet louvres located at roof level. This system was initially found to allow insufficient heat transfer from the powerhouse. We carried out detailed thermal analysis and recommended improvements to allow reasonable operating temperatures within the powerhouse.
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Initially, insufficient flash vessels were fitted in the steam system. This under sizing on the steam lines could have a detrimental effect on the operation of the steam system as a consequence of water-hammer effects from water steam carryover. Our team immediately identified the insufficient flash vessels as being a major risk and they were rectified before any testing took place.
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During peak load operation of the plant, it was expected that up to 35 x 40,000 litre fuel oil tankers would enter and leave the site daily during daylight hours. This traffic load, together with the vehicular traffic expected for operation and maintenance of the plant, could potentially cause bottlenecks and carry a higher risk of accidents at the site. HUBCO engaged us to prepare a traffic management plan. Careful planning resolved the potential issues associated with fuel unloading.
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Steam sootblowers exhibited signs of excessive vibration and in time could lead to fatigue failure. Through investigative (FMEA) techniques, we advised suitable support structures to be improved on and excessive vibration has since been eliminated.
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Various delays were encountered throughout the project. We provided HUBCO with high level analyses on such delays, including scope to reduce critical path activities.
Value and benefits
Mott MacDonald was able to provide local support for the project through our offices in Lahore, Pakistan, complementing our specialist international knowledge of diesel power generation with an understanding of the local business environment. We also provided support on the project as a whole through the wide range of services offered across the Mott MacDonald Group. Our expert knowledge in dispute resolution also proved of benefit.