Hydrates are ice-like crystals formed when water surrounds gas molecules at low temperatures. This is the one of biggest problems at Gas plants. Indication 1 It decreases the flow. 2 increases DP 3 Blocks Tubing Prevention 1 Methanol Injection. 2 Increase Temperature 3 Provide Heat tracing

A cascade control loop uses two controllers, where one controls the setpoint of the other for better stability.Can be 2 element or 3 element. One is Master others are slaves. Example Steam drum Level Controller / Absorber level Controller