Estimating Fired Heater Coils Safety Time using Transient Analysis

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Title Estimating Fired Heater Coils Safety Time using Transient Analysis
Creator Ahamad, S.
Contributor Thakur, M., Izadi, M., Vallavanatt, R.
Date 2017-12-11
Description Paper from the AFRC 2017 conference titled Estimating Fired Heater Coils Safety Time using Transient Analysis
Abstract During the operation of a fired heater there are potential for sudden interruption of process flow. This could be due to pump trip or accidental closing of a valve in the inlet line. When this happens the fuel must be cut off to protect the process coils. It is critical to ensure that these coils do not fail or degrade when process flow is stopped. Therefore, an estimation of safety time becomes critical. The firing in fired heater must be isolated within the estimated safety time. An adequate control system must be designed to ensure that the fuel gas is isolated within safe time. Safety time estimation is crucial for control loop design of equipment in the operating plant.; Most of the heat transfer problems in fired heater are simulated as steady state. However, in this case, a transient heat transfer calculation is required. The intent of this transient analysis is to study the following:;  Analyze and obtain analytical solutions for transient heat transfer considering the effect of radiation as well as convection heat transfer;  Predict the variation of temperature with time, and;  Eventually, calculate the safe time for coil before it degrade / fail; A paper was published in 2014 discussing a semi-analytical method that was proposed by author et al. The results are used to estimate Safety Time to avoid failure of tubes in fired heaters. The semi-analytical method can be used in Fundamental Engineering and Evaluation Designs (FEEDs), Hazard and Operability studies (HAZOPs) and Hazard Identification (HAZID) studies for LNG plants and power plants. This paper proposes a method to estimate the time verses tube wall temperature for Fired Heater coils.; To verify the semi-analytical methods proposed earlier, a dynamic simulation is performed in this paper to estimate tube wall temperature versus time for a fired heater in a typical LNG plant. The process dynamic simulation tools Aspen HYSYS will be used for dynamic simulation in this study. A Fired Heater detailed model along with process control scheme will be used for analyzing operating conditions. The upset condition of process fluid failure shall be evaluated and its effect on fired heater and plant shall be evaluated.; The paper will present case studies for a fired heater coil's safety time estimation. The operating control loop, which includes several components, is required to be capable of isolating the system much ahead of the estimated safety time. The control loop is designed to achieve an equipment isolation time of lower than that of the calculated fail safe time.; The result of this study has been successfully implemented on recent projects.
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Format application/pdf
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Metadata Cataloger Catrina Wilson
ARK ark:/87278/s65n0gr8
Setname uu_afrc
Date Created 2018-12-10
Date Modified 2018-12-10
ID 1388797
Reference URL