CONTROL OF A FLUID CATALYTIC CRACKING UNIT
The performance of the FCC units plays a major role on the overall economics of refinery plants. Any improvement in operation or control of FCC units will result in dramatic economic benefits. Present studies are concerned with the general behaviour of the industrial FCC plant, and have dealt with the modeling of the FCC units, which are very useful in elucidating the main characteristics of these systems for better design, operation, and control. Due to the large economic benefits, these trends make the process control more challenging. There is now strong demand for advanced control strategies with higher quality to meet the challenges imposed by the growing technological and market competition. Usually, the optimum operating conditions are met where constraints are also active. As a consequence, it is important to control FCCU as close as possible to the operating and equipment constraints but without violating them. This study reviews different control approaches of the fluid catalytic cracking unitaimed to control the main variables of the unit and to demonstrate the benefits of the control for the FCC unit.
BACKGROUND OF STUDY
Public enterprises were established, to enhance Nigeria’s socio economic development, especially after independence in 1960. The major concern in this regard had been to accelerate development and economic self-reliance through ‘’economic nationalism.’’ Public enterprises thus reflect one of those instruments by which government intervenes in economic development rather than allow market forces to dictate the pace of development. According to Ayodele (2004), Nigeria relied heavily upon public enterprises, up to the mid-1980s, for the development, management and allocation of utilities and social services. They were seen as major instruments not only for the mobilization and allocation of public investment resources, employment generation and income redistribution, but also for determining government finances and the acceleration of overall economic development.
Adeyemo (2005), reflecting on Turkey, Mexico, India and Nigeria, noted that the establishment of public enterprises was premised on what he considered as obstacles to economic development in the post-independence states. It is also instructive to note that in Nigeria like many developing countries, public enterprises are used as employers of last resort. According to Hemming and Mansor (1988), state owned enterprises enable governments to pursue goals of social equity that the market ordinarily ignores. Similarly, Ugorji (1995) observed that public enterprises had been established for political reasons.