A method for crystallization cooling control in a process plant, the method comprising: capturing process parameters of an operating reactor unit in a process plant, wherein the process parameters are captured via one or more sensing units (104A-B, 106, 110); predicting desired process parameters based on first set of parameters and the captured process parameters, wherein the first set of parameters comprises information related to process dynamics and process disturbances associated with the operating reactor unit, where the step of predicting the desired process parameters is further characterized by the following steps: determining actual flow of utility into the operating reactor unit based on the captured process parameters; comparing the desired utility flow for the operating reactor unit with the actual flow of utility to determine a utility flow error value; generating a control signal indicating a change of position of a smart positioner (114A-B) of a control valve configured for positioning a control element and controlling flow of utility into the operating reactor unit based on the utility flow error value; determining current position of the smart positioner (114A-B) using the captured process parameters; transmitting the generated control signal to the smart positioner (114A-B) via a control system; determining hysteresis value associated with the smart positioner (114A-B); and repositioning the smart positioner (114A-B) based on the transmitted control signal, wherein the repositioning of the smart positioner (114A-B) rectifies the utility flow error value to zero value; and controlling process control loop associated with the operating reactor unit based on the desired process parameters, the first set of parameters and the utility flow error. capturing process parameters of an operating reactor unit in a process plant, wherein the process parameters are captured via one or more sensing units (104A-B, 106, 110); predicting desired process parameters based on first set of parameters and the captured process parameters, wherein the first set of parameters comprises information related to process dynamics and process disturbances associated with the operating reactor unit, where the step of predicting the desired process parameters is further characterized by the following steps: determining actual flow of utility into the operating reactor unit based on the captured process parameters; comparing the desired utility flow for the operating reactor unit with the actual flow of utility to determine a utility flow error value; generating a control signal indicating a change of position of a smart positioner (114A-B) of a control valve configured for positioning a control element and controlling flow of utility into the operating reactor unit based on the utility flow error value; determining current position of the smart positioner (114A-B) using the captured process parameters; transmitting the generated control signal to the smart positioner (114A-B) via a control system; determining hysteresis value associated with the smart positioner (114A-B); and repositioning the smart positioner (114A-B) based on the transmitted control signal, wherein the repositioning of the smart positioner (114A-B) rectifies the utility flow error value to zero value; and determining actual flow of utility into the operating reactor unit based on the captured process parameters; comparing the desired utility flow for the operating reactor unit with the actual flow of utility to determine a utility flow error value; generating a control signal indicating a change of position of a smart positioner (114A-B) of a control valve configured for positioning a control element and controlling flow of utility into the operating reactor unit based on the utility flow error value; determining current position of the smart positioner (114A-B) using the captured process parameters; transmitting the generated control signal to the smart positioner (114A-B) via a control system; determining hysteresis value associated with the smart positioner (114A-B); and repositioning the smart positioner (114A-B) based on the transmitted control signal, wherein the repositioning of the smart positioner (114A-B) rectifies the utility flow error value to zero value; and controlling process control loop associated with the operating reactor unit based on the desired process parameters, the first set of parameters and the utility flow error.