(104ak) Plant Safety Through Process Control

A study was performed by Miller (2000) on 26000 PID control loops data collected between 1998 & 1999 and the result showed that two thirds of the controllers were classified as unacceptable performers. Later, HUGO (2002) reported more than 88% of control loops perform ineffectively. These figures clearly shows that current operation practices do not consider the process control layer as one of the plant layers of protection that need to be well maintained to improve plant safety. Even though, BPCS is considered the first layer of protection after inherently safe plant design. As a result of current operation practices, many catastrophic refinery incidents had occurred. These incidents could have been avoided if the BPCS layer was working effectively and well maintained. In addition to its regulatory function, BPCS could be used to enhance plant safety by minimizing the escalation of process deviation and plant upsets to a major disaster. BPCS also enhance plant performance by reducing rate of equipment trips and failure, minimizing flaring (carbon credit), optimizing energy consumption and maximizing asset integrity. The BP Texas City Refinery (March 2005) with some other incidents will be discussed. A catastrophic release of hydrocarbons resulted in fires and explosions that caused the deaths of 15 workers and injured more than 170 others. The BP final report clearly states that the incident would not have occurred if the process control system was placed on automatic control during the startup when the raffinate tower level passed 50%.