An experimental study of unstable states in a loop reactor

Abstract
An adiabatic loop reactor was operated at naturally unstable steady states in experiments employing the reaction between sodium thiosulfate and hydrogen peroxide in aqueous solution. The unstable states, the intermediate states in a multiple state regime, were stabilized by manual manipulation of the recycle ratio. Resulting temperature data agreed well with those predicted from a plug‐flow model. Observations of the transient response to small disturbances from the intermediate states verified that they were indeed unstable as had previously been predicted theoretically. Cursory attempts to stabilize the system by means of automatic feedback control employing a three‐mode controller were unsuccessful.