Heat integration upset

Emergency Conditions in Integrated Plants - In integrated plants, a process upset in one unit may have an effect on other units (e.g., loss of flow of a pumparound which is used as a source of heat for reboiling other towers). All possibilities such as these must be carefiiUy considered and the potential for resulting overpressure evaluated. 

In industrial applications the achievement of higher activity and selectivity is of course desirable. However, beyond a certain point, they are not the driving forces for extensive research. For instance, current processes for epoxidation of ethylene to ethylene oxide on silver catalysts are so optimized that further increases in selectivity could upset the heat-balance of the process. Amoco s phthalic acid and maleic anhydride processes are similarly well energy-integrated (7). Rather than incremental improvements in performance, forces driving commercial research have been... 

Many processes require speed controls. Performance and reliabilities of these controls are very similar to those of the temperature controls—you get what you purchase. Early speed controllers, like the temperature controllers, were mechanical. Speeds were held within 5 percent, resulting in poor plastic melt control. Where better speed control is desired, the solution is the same as in temperature control only the equipment names are changed. A device is added to the motor, and an integral characteristic is provided, corresponding to the automatic reset with heat. It brings the speed closer to the set point. A derivative characteristic, corresponding to the rate in heat, ensures a prompt response to any upsets. 

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