Propane pre-cooling and mixed-refrigerant process

an efficient and simple process and a combination of cascading liquefaction and mixed-refrigerant liquefaction processes

is the most common natural gas liquefaction process by now. Due to the interference of external factors in the actual situation

it is necessary to maintain the stability of liquefaction plant by the controller. Hence the dynamic simulation analysis for the liquefaction process control system is needed. In this paper

the flexibility of liquid level control

temperature control and cascade control in the systems of propane pre-cooling and mixed-refrigerant process is simulated respectively by dynamic simulation

and then the response of liquefaction process and the responding time to stability can be known by changing the settings of controller. In this way

the optimal control mode of each system has been got. It indicates that the systems have better stability and faster responding speed when the propane pre-cooling system adopts liquid level control or cascade control

mixed refrigerant process applies the liquid level control

and the gas system uses cascade control.