Modeling and Simulation of an Industrial Top-Fired Methane Steam Reforming Unit

Abstract

This work aims to develop a stationary phenomenological model of an industrial steam reforming unit. Unlike the usual approach in the literature, the combustion reactions at the furnace are described through rigorous distributed mass and energy balances to predict the concentration and temperature profiles along the length of the equipment. A more precise prediction of these profiles is useful for understanding and monitoring the quality of the outlet gas for different inlet conditions without the need to know the length of the flame. This model further considers the refractory as an additional control volume, allowing us to predict and avoid temperature gradients that could damage the equipment and lead to operational downtime. The heat transfer effects are described in detail as the radiation reabsorbed by a different element inside the same phase (i.e., two tubes or refractory walls exchanging radiant energy), the radiant heat absorbed by the gas inside the furnace, and the heat transferred by radiation inside the tubes. The model is validated against different case studies using industrial and literature data. The model predicts reformed and flue gas compositions with maximum relative deviations (with respect to experimental data) of 3.27% (case 1) and 11.14% (case 5), respectively, proving the adequacy of the proposed model. Sensitivity analysis is performed to investigate the influence of some heat transfer phenomena, often neglected in the literature, on the performance of the developed model. Through this analysis, it was possible to identify the most important heat transfer phenomena (the radiant energy exchanged intraphase, i.e., between two tubes, and between phases, i.e., the tube and the process/furnace gases) and those that are negligible (convective heat transfer at the furnace). The proposed model might be useful for process monitoring as well as optimization.

Century of Technology Trends in Methanol Synthesis: Any Need for Kinetics Refitting?

“…Either way, nowadays methanol is still mainly produced starting from fossil sources. , There are several chemical processes to convert fossil fuels into syngas, and the rate of technological advances is speeding up for this step (Figure ). Currently, the most popular ones are steam methane reforming (SMR), − autothermal reforming (ATR), ,− partial oxidation (POX), , and coal gasification (CG) . In the past years, due to the large availability of coal mines, many institutions devoted great efforts to making more appealing and environmentally sustainable CG plants mainly driven by the growth of the Chinese internal methanol market. , More recently, different strategies have been proposed to reduce the environmental impact of CG plants for methanol synthesis: the use of biomass from anaerobic digestion as an alternative feedstock ,− or the application of more innovative technologies to obtain syngas while purifying streams from common coal pollutants such as carbon dioxide and H 2 S (AG2S technology − ).…”

Biogas to Syngas through the Combined Steam/Dry Reforming Process: An Environmental Impact Assessment

“…A generator produces high-temperature steam that is sent to the reformer after being mixed with the carbonaceous gas stream. The heat required for the reaction is provided by the burning part of the natural gas fed. − This combustion produces an exhaust stream that can be thermally valorized through different heat exchangers placed before the reforming reactor. One of the main drawbacks of this process is that a syngas suitable for a gas-to-liquid system is hardly attainable through a one-step steam reforming reactor (eq ) that, due to the excess of steam used in the process, can easily promote the occurrence of the water gas shift (WGS) reaction (eq ) producing syngas with H 2 /CO > 3.…”

Modeling Kinetic, Thermodynamic, and Operational Effects in a Steam Methane Reformer. Part A: Reformer Output

“…A Python model of the tube side of the reformer has been developed as detailed by Holt et al, 2 which is an extension of the model developed by Xu and Froment. 3 The model of Holt et al includes more accurate estimations of various process parameters and the reaction mechanisms of higher hydrocarbons (HHC) (C 2 −C 4 ) as presented by Seong et al 4 This model of the catalyst-filled tube is more detailed than some recently published 1D models, 5 albeit lacking direct modeling of the reformer furnace. In a separate study, a version of this model was validated using non-linear regression against industrial data, incorporating time-dependent degradation of the catalyst through sintering, poisoning, and crushing.…”