Sierra Pacific's Coal Gasification Plant
Coal Handling System Review

Photo credit: TEMCOR

Client
Foster Wheeler Power Systems
Perryville Corporate Park
Clinton, New Jersey 08809-4000

Completion Date
November, 1995

Project Description
Foster Wheeler Power Systems (FWPS) designed and constructed a 100 MW IGCC unit, at the Tracy Station of Sierra Pacific. The existing units at the Tracy Station were fueled by oil and gas. A new coal handling system was added by FWPS for the coal gasification unit. Energy Associates was engaged to review the basis of the design, construction, and operation of this coal handling system. This review focused on design aspects, which affect the reliability of the coal handling system and its ability to operate under the complete range of specified fuel quality and ambient conditions at the plant.

The IGCC unit utilizes sub-bituminous and bituminous coals as those found in Utah, Colorado, Wyoming, and Montana. Coal is delivered by the Southern Pacific Railroad, whose main rail line is adjacent to the site. Coal is shipped in rapid discharge unit trains. These are bottom dump rail cars that can rapidly unload via actuator operated doors. Coal receipts are weighed and sampled.

The coal stockpile is enclosed in a dome, which is pictured above. Within the dome, a circular stacking and reclaim system handles the coal. Mobile equipment is used only during emergencies.

The reclaim/processing system screens and crushes the coal. A closed loop system is used to ensure that only sized coal is directed to the gasifier. Tramp metal is removed via magnetic separators. Day silos will store processed coal, coke, and limestone. The IGCC unit uses coke as start-up fuel. Limestone is blended with the coal. Unit waste includes a limestone-ash (LASH) by-product.

Issues identified in the review include the following:

1. Add provisions at the dumper for re-railing cars and preventing coal flushing.

2. Revise some chutes to improve coal flow.

3. Review the structural loads imposed on the stacker/reclaimer during construction.

4. Provide additional dribble/spillage clean-up provisions.

5. Review clearances for plant traffic beneath a conveyor.

6. Incorporate modifications that would enable the plant to feed coal to the coke silo to double the day storage capacity at a marginal additional cost.

7. Test LASH to identify flow characteristics and chemical properties for this "new" material.