Fuel Blending System Program
for the
300 MWe AES Cayuga Plant

Client

AES Cayuga
228 Cayuga Drive
Lansing, New York 14882-8896

Completion Date

May, 2008

Project Description

Energy Associates was engaged by AES Cayuga to investigate the addition of a fuel blending system.  Energy Associates completed the original feasibility study and upon project approval, completed the detail design and reviewed/approved contractor submittals for this project.

The AES Cayuga Plant (previously the Milliken Station) consists of consists of Units No. 1 and 2 commissioned in 1955 and 1958.  Each pulverized coal boiler is rated roughly 150 MWe.  In 1994, an SCR was added to unit No. 1 and a FGD system was added for the plant.  Some changes where made to the coal stockpile area and bunker outlets/feeders.  Some of the original coal handling equipment, such as belt scales and a sample system on the reclaim system, have been removed.

For AES Cayuga, fuel is the plant�s major operating cost.  It has been targeted as a potential source for reducing plant cost and improving plant dispatch.  Because the plant is already fitted with an FGD scrubber, it can utilize high sulfur opportunity fuels, blending it with its base, Pennsylvania coal for instance.  Petroleum coke is an example being considered by the plant.  This is a high sulfur, high heating value fuel.  Because petroleum coke is low in volatile matter, it cannot be directly combusted in most pulverized coal units as the primary fuel.  Blending petroleum coke with a relatively high volatile coal, which is the plant�s primary fuel, is a successful strategy being used by some pulverized coal power plants.

AES Cayuga�s coal handling system was designed to efficiently unload, crush, and reclaim a single coal.  The existing, fixed, luffing stacker is an obstacle to segregating piles.  There is only one discharge point.  Complicating plant operations, the discharge point is located directly over the reclaim hoppers, coal that is to be segregated must be immediately bulldozed away from the discharge of the stacker.  Otherwise, the reclaim hopper directly below will feed this coal to the bunkers.  If this is not promptly and carefully done, a slug of low-grade fuel can be feed to the boiler upsetting plant conditions.  Conversely, reclaiming slugs of higher, more costly grade fuels frustrate the plant�s ability to minimize fuel cost.  The plant has received different coals by rail and truck, experimenting with a rudimentary blending arrangement using mobile equipment.  This effort highlighted the need to consider modifications that will improve blending control and consistency.

Handling a second fuel and blending the two required modifications/additions to the coal handling system.  Energy Associates examined a variety of concepts in the feasibility study.  A unique feeder/conveyor concept was developed, which allows the plant to blend fuel with the addition of a single, major component � the feeder/conveyor.  The feeder/conveyor also increases fuel system redundancy and reliability, allowing the plant to continuing reclaiming coal if the primary reclaim hopper is out-of-service.� Illustrated blow is the low speed hydraulic drive motor that enables the feeder/conveyor to operate with infinite belt speed variation from 15 to 300 fpm, a capacity range of 30 to 600 tph.