Coal Handling System Review of ENEL’s Sulcis Plant, Sardinia, Italy

Client

Sigma Energy Solutions One Huntington Quadr, Suite 4S09 Melville, New York 11747

for

ENEL Produzione SpA 09010 Portoscuso (CI) Z.I. Portovesme

ALSTOM Power, ITCOM Viale Edison 50 Sesto San Giovanni, Italy 20099

Completion Date

January, 2010

Project Description

The Sulcis Plant currently has two (2) units. Unit No. 3 is a 240 MWe pulverized coal boiler, which has been retrofitted with an FGD system. The original Unit No. 2 was replaced by a 350 MWe Alstom Power circulating fluidized bed (CFB) boiler. Unit No. 1 was removed.

Coal is supplied by local sources and from Columbia and South Africa. The lower quality local coal is blended with the overseas coal during reclaiming. Coal is stockpiled in an open/outdoor stockpile and also within a protected concrete shed/structure. Mobile equipment is employed to reclaim/blend coal.

The new CFB unit experienced problems maintaining full load for periods longer than ten (10) hours when high moisture coal was used. The ultimate goal of ENEL was to have the plant able to generate full design capacity whenever required. The scope of work included a review of the coal handling system and recommendations regarding modifications and/or upgrades of the existing system.

The boiler fuel feed system extends from the outlet of each individual coal bunker of the original Unit No 2 to the inlet of the new CFB boiler and the cyclone/seals. This system includes a variety of equipment to control the feed rate, size the coal, convey/split the coal streams, and inject it into the CFB boiler. The feed rate is regulated by volumetric belt feeders. Particle size is controlled by impactor crushers. En-masse conveyors elevate the coal at steep angles from grade to the front and rear of the boiler. Dual flap valves provide a pressure seal on the front of the boiler. Prior to beginning this task/assignment, ENEL completed a variety of modifications to alleviate coal flow problems, but these did not achieve the desired result. Pictured above is ENEL’s modification to the section of the fuel feed system, which is between the crusher and inlet to the en-masse conveyor for one (1) of the six (6) fuel feed conveying lines.

A variety of long-term and near-term concepts and options were developed for ENEL’s consideration. Issues pertaining to Sulcis’ coal; design/operation of the receipt, storage, and handling systems; design of the fuel feed system; and the details of equipment design/interfaces were addressed. Fuel is the largest single component of a power plant’s operating cost. Reducing fuel cost is typically a prime objective for the fuel procurement manager. Problems in feeding coal to the CFB boiler, however, impact its ability to meet full load for extended periods, which can directly impact plant production. Both issues – fuel cost and plant availability - are key factors for plant economics and the reason why ENEL authorized this investigation.