The site required the replacement and upgrade of the existing dated and inefficient Hamworthy oil fired burners. The turn down was in the region of 3-1 which added to the burner recycling issues.
The Hamworthy burners were replaced by state of the art Oilon GKP500-M DN80 duel fuel burners to both boilers. The new burners are capable of operating at low oxygen levels throughout the modulation range and achieve up to a 10-1 turn down on gas and 3.5-1 on oil, resulting in substantial fuel savings. They also have a VSD operating the FD fan with around 50% saving on the running electrical costs of the burner.
A significant additional benefit emanating from the Oilon burner is the use of a constant velocity combustion head. This will maintain the air flow velocity throughout the firing range, optimising O2 levels. This along with digital modulation allows the burner to operate safely at O2 levels of less than 2% at high fire on gas through to 3.5% at low fire, without the creation of CO.
Further savings were made by converting the burners to a digital Ecosafe control system which allowed boiler sequencing. A varying load optimised the boiler control logic which resulted in further savings and the fitting of a retrofit flue gas economiser to the lead boiler achieved maximum efficiency, with the second boiler on lag.
SAVINGS:
By improving burner/boiler turndown ratio from 3-1 up to 10-1 and reduced cycling, provided a fuel saving of up to 5%.
By improving combustion efficiency and reducing excess oxygen levels across the modulation range (By reducing excess oxygen levels from 6% to 3.5% at low fire where the burner sits for the majority of time will provide a fuel saving of 2% at a point in time).
Providing state of the art control system and repeatability will give a fuel saving of 1%.
Electrical consumption – variable speed drives reduce electricity costs by matching the speed of the burner motor to burner/boiler load and achieving electrical savings in the range of 50%.
Additional savings of up to 6% with the addition of a flue gas economiser.
Achieving total savings of 13.96% in fuel savings, plus electrical savings on top of this.