A method and system are provided for reducing the volume and/or frequency of slugging in a fluid processing system that includes a pipeline for conveying produced fluids and a vessel for receiving the produced fluids from the pipeline. A control valve is provided in the pipeline upstream of the vessel. A pressure sensor and/or a level sensor is coupled to the vessel. Pressure information from the pressure sensor and/or level information from the level sensor is sent to at least one master control loop in a cascade control scheme. The master control loop output determines a set point of a slave control loop coupled to the control valve to achieve a pressure setpoint or a level setpoint. The slave control loop, also referred to as a pseudo-flow controller, determines whether the control valve opening needs be modulated to achieve the setpoint of the slave control loop. A method is also provided for retrofitting an existing fluid processing system.