Reconciliation of a Pyrolysis Reactor

Stream Reconciled with bias Reconciled without bias 

The pyrolysis reactor is an important processing step in an olefin plant. It is used to crack heavier hydrocarbons such as naphtha and LPG to lower molecular weight hydrocarbons such as ethylene. The pyrolysis reactor, in this study, consists of two identical sides each side contains four cracking coils in parallel (see Fig. 2). 

FIGURE 2 Simplified scheme for the industrial reactor (from Weiss et al., 1996). 

Then the cooled gases from the two sides are mixed together for further processing downstream. There are several pyrolysis reactors within the industrial complex. 

An advanced control system has been implemented for efficient operation of the pyrolysis reactor. However, it faced problems due mainly to the difficulty of measuring the high coil and coil skin temperature reliably and consistently, because of regular drifting of the high-temperature sensors. Thus, there is a need for a data reconciliation package (DRP) to increase the level of confidence in key measured variables, to indicate the status of sensors, and to estimate the value of some unmeasured variables and parameters (Weiss et al., 1996). 

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DATA RECONCILIATION OF A PYROLYSIS REACTOR 12.3.1. Process Description... 

The overall heat transfer coefficient calculated using the joint parameter estimation and data reconciliation approach is shown in Fig. 9. It is evident from this figure that the overall heat transfer coefficient remains fairly constant throughout the whole operating cycle of the pyrolysis reactor. Near the end of the cycle, the heat transfer coefficient drops to a comparably low value, signifying that the reactor needs to be regenerated. 

In the second example, that of an industrial pyrolysis reactor, simplified material and energy balances were used to analyze the performance of the process. In this example, linear and nonlinear reconciliation techniques were used. A strategy for joint parameter estimation and data reconciliation was implemented for the evaluation of the overall heat transfer coefficient. The usefulness of sequential processing of the information for identifying inconsistencies in the operation of the furnace was further demonstrated. 

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