Energy Conservation Opportunity with Variable Frequency Drive in Boiler House

Energy saving is necessary for saving fuel and energy cost in industry. The energy saving has become one of the main objective of the international and national policies. A Considerable level of energy losses are accepted reality in a large number of industries and there is evident potential for energy efficiency improvements. Electric motors use two-third of all electricity in industry, so any chance to reduce this load, even by single figures is highly significant. Most pumps and fans are oversized for the duties they perform. Also electrical motors are available in specific speed range. Pumps and fans are coupled with electric motor to perform their duties. The boiler house equipment such as forced draft fan Induced draft fan and boiler feed pump rotates at constant speed and there is too much energy losses. By using a Variable Frequency Drive (VFD) to slow down a fan or pump motor speed from 100% to 80% can save as 50% of energy. Reducing fan speed not only reduces energy consumption but also reduce noise and vibration. Boiler feed pumps consume a large fraction of the auxiliary power (in excess of 4 % of unit capacity) used internally within a power plant in pressurizing and forcing the feed water through economizer to the boiler. The changing rotation speed is the most effective and economical way of improving the pump efficiency. Adjustments made to rotation speed causes only a slight decrease in the pump efficiency compared to operation with fixed revolutions. This type of control allows a reduction in electricity consumption in a wide range of loads. The VFD installation cost, the financial burden is balanced against the earning resulting from the associated energy saving.