MV Drive Solution for Boiler Feed Water Pump
Application: Boiler Feed Water Pump with 6.6kV VFD Replacing existing throttling control with VFD, benefits and energy savings
|Application:||Boiler Feed-Water Pump 2x 1600 kW, 6.6kV|
One of the leading energy companies producing and distributing electricity in UP having 60MW unit in UP. The Plant is in production since March 2009. Complete plant was supplied and commissioned by Chinese manufacturer and majority of high power (200kW and above) auxiliary applications with 6.6KV Chinese make motors with various method of speed control other than VFD.
As the loading of a power plant can vary from minimum load to peak load due to various internal and external factors, the plant’s processes have to be adjusted accordingly. Driving the pumps with fixed speed motors and controlling them at partial loads either by throttling or mechanically by fluid coupling decreases the power plant’s efficiency tremendously.
Given the efficiency problem of boiler feed water pumps driven by fixed speed motors at partial loads, the most economic control is achieved with a variable speed drive system.
Discussion started with energy saving based proposal from Ethan Power Pvt. Ltd.
After evaluating complete data and energy saving report procurement process started and by converting this order to turnkey package of civil & electrical end to end solution we could limit the competition securing a turnkey order including 1600KW, 6.6KV VFD, 2MVA transformer and Bypass Isolator panel for achieving 2 motors with 1 VFD scheme, VFD and bypass DOL scheme.
Boiler feed water pumps are one of the biggest energy consumers in a power plant. Operating feed water pumps with variable speed drives can significantly increase the efficiency of a power plant. Outside the boiler feed-water pump’s nominal range, the capacity needs to be sufficient to handle rare but possible abnormal situations in a boiler that operates under very high pressure. Depending on the local authorities’ requirements, the pump – and the supplying drive – have to be capable of delivering 10-25 % over pressure or overflow. As a consequence, the drive operates practically all the time under partialload, a situation where a variable speed drive offers the best available efficiency.
Using ACS2000 variable speed drives as level control device offeed water drums can reduce maintenance of the feed-water throttling valves. These haven’t necessarily been designed for the full pressure differential resulting from throttling the flow with fixed speed motors.
Further savings can be achieved by designing a new generating unit’s electricity distribution network for feed-water pumps operated by frequency converters. As main loads, their across-the line starting behavior typically impacts on – depending on impedance of the plant transformer- capital cost, either through a more expensive transformer,through higher fault currents, or a more expensive switchboard. Variable speed drives as such act as soft starters and cause no starting current peaks.