Endogenous and exogenous dynamics of pressure fluctuations in an impinging entrained-flow gasifier

TL;DR

This withdrawn paper aimed to analyze pressure fluctuations in an entrained-flow gasifier but was retracted due to a fundamental error in handling non-stationary data, invalidating its conclusions.

Contribution

The paper attempted to study pressure dynamics in a gasifier using statistical analysis, but the approach was flawed due to non-stationary signals, highlighting the importance of proper data handling.

Findings

Analysis was invalid due to non-stationary signals

Methodology was inappropriate for the data type

Paper was withdrawn due to analytical errors

Abstract

This paper has been withdrawn by the authors due to a fatal error in the analysis. The manuscript was submitted to Chemical Engineering Science. To clarify the situation, we copy the main comment from an anonymous referee here: "To my understanding, the authors analyze i = 1 ... 63 time series and calculate their mean and standard deviation. These time series correspond to individual, single ignition processes. Is this correct? If yes, these processes, as Fig. 3 shows very clearly, are not stationary, and the pressure difference (i.e., the signal) quickly decays to zero. In this case both the mean and the standard deviation are poorly defined, for example because both depend in a trivial fashion on the observation period T. I am not aware of any study (including those cited by the authors) which allows for any conclusion from such non-stationary signals. The results of Menezes and Barabasi are strictly only valid for stationary time series, and they cannot be applied at all in this case." We agree with this insightful comment that our data are not stationary and the method adopted in our manuscript does not apply. We do not see any possibility to correct this error and decide to withdraw it. We would like to thank gratefully the referee and apologize for any inconvenience caused by our oversight.