NISCO Cogeneration Facility

The NISCO Cogeneration facility utilizes two fluidized bed boilers to generate 200 MW of electricity and up to 80,000 LBS/HR of steam for process use. The partnership, of three industrial electricity users, Citgo, Conoco, and Vista Chemical, and the local utility, Gulf States utilities, was formed in the late 1980's. In August and September 1992 two fluidized bed boilers were brought into operation to repower existing turbine generating equipment. The fluidized bed units were designed to utilize 100 percent petroleum coke, a locally produced fuel. Petroleum coke is a high heating value, low volatile, high sulfur fuel which is difficult to utilize in conventional boilers. It is readily available in most areas throughout the world, including North and South America. Because of superior environmental performance, lower capital cost, and fuel versatility, circulating fluidized bed boilers were selected to repower the existing turbines. Fluidized bed boilers were ideally suited for a repowering application. Existing equipment matched or was modified for utilization in the project optimizing capital cost. The fluidized bed boilers, designed and fabricated by Foster Wheeler, are each capable of producing 825,000 LBS/HR of steam. This paper describes the results attained at NISCO during the first full year of operation. The design attributes of the project which enabled a successful and efficient unit startup are explained. Descriptions of design enhancements and modifications installed during the first year to improve the operability of the repowered facility are included. This paper describes technology and experiences of value to those considering steam generating unit repowering or construction