Machine startup/shutdown

Interlocks are commonly used safety devices. The function of an interlock is to prevent the occurrence of an event in the piesraice of certain conditions. Some interlocks prevent action or motion, others send signals to other devices that prevent the action or motion. They automatically reconfigure or interrupt final control devices if monitored variables deviate significantly from specifications. Typical process variables monitored are flow, pressure, level, and temperature. Typical machine variables monitored are coolant level and temperature, lubricant level and temperature, vibration, speed, etc. Interlocks allow equipment to start and operate only when monitored variables are within designed specifications. Interlocks inhibit unanticipated actuation of equipment and ensure correct startup/shutdown sequences are followed. A permissive interlock will not allow a process or equipment to startup unless certain conditions are met. There ate two types of interlocks—safety and process interlocks. Each serves a different function. 

Repeated twisting of the spindle s tube or the solid shaft used in jackshafts results in a reduction in the flexible drive s stiffness. When this occurs, the drive loses some of its ability to absorb torsional transients. As a result, damage may result to the driven unit. Unfortunately, the limits of single-channel, frequency-domain data acquisition prevents accurate measurement of this failure mode. Most of the abnormal vibration that results from fatigue occurs in the relatively brief time interval associated with startup, when radical speed changes occur, or during shutdown of the machine-train. As a result, this type of data acquisition and analysis cannot adequately capture these... 

Synchro-Self-Shifting ( SSS ) Clutches The automatic freewheel action of an SSS clutch simplifies plant startup and shutdown sequences. It is, of course, receiving its power input from a gas turbine or similar driver, while its output is connected to a driven machine. The drive disengages automatically when the driven machine speed exceeds that of the driver. Since large gas turbines are usually brought up to speed with either a startup gear motor or a helper turbine, thousands of SSS clutches (Fig. 29-77) are finding application here. 

In the operational optimization, the task is to schedule startups and shutdowns of refiners in order to minimize the production cost when the demand of the paper machine and the price of the electricity are known over a given time horizon. 

For lube and seal oil systems, provision of interlocks to prevent startup of the machine unless the oil system is operating backup systems. Alarms (or shutdowns) in case of high bearing temperature and low oil flow. 

---