Interlock control instructions for cascade control systems – Process automation requirements
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The process flow is described as follows: a reboiler is installed at the bottom of the regeneration tower; the saturated glycol, from which water has been absorbed, is heated by the reboiler, causing the water to be desorbed and the mass concentration of glycol to increase. The heat source for heating the reboiler is heat transfer oil. In order to achieve stable control of the temperature at the bottom of the tower and reduce temperature fluctuations during operation, the process uses the temperature of the glycol in the reboiler as the primary control parameter, while the flow rate of the heat transfer oil is used as the secondary control parameter, thereby enabling cascade control of the reboiling temperature. Now it is necessary to provide relevant control instructions for the automation control specialty; how can these automation control requirements be specified accurately? Could fellow marine engineers provide relevant interlock control specification templates for reference? Thank you.
This is not just cascade control of the reboiler temperature and hot oil flow rate, as the temperature difference between the hot oil inlet and outlet also plays a role in the control. How does it contribute to the control? What is the calculation relationship? I’m not sure.