Transport Mechanism of Steam Methane Reforming on Fixed Bed Catalyst Heated by High Temperature Helium for Hydrogen Production: A Computational Fluid Dynamics Investigation

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Feng Wang ◽  
Ziqiang Yang ◽  
Long Wang ◽  
Qiang Wen
Keyword(s):  
High Temperature ◽  
Hydrogen Production ◽  
Temperature Difference ◽  
Fixed Bed ◽  
Inlet Temperature ◽  
Methane Reforming ◽  
Outlet Temperature ◽  
Inlet Velocity ◽  
Steam Methane Reforming ◽  
Steam Methane

In this study, we numerically evaluated the performance of a steam methane reforming (SMR) reactor heated using high-temperature helium for hydrogen production. The result showed that with an increase in the reactant gas inlet velocity, the temperature at the same reactor length position decreased. The maximum gas temperature difference at the gas collection chamber reached approximately 55 °C. The outlet temperature difference increased to 35 °C when the inlet temperature increased from 370 °C to 570 °C. A higher inlet temperature did not have a positive effect on the system's thermal efficiency. The methane conversion rate increased by 68%, and the hydrogen production rate increased by 55%, when the helium inlet velocity increased from 2 m/s to 22 m/s. When the helium inlet temperature increased by 200 °C, the highest temperature of the reactant gas increased by 132 °C. In the SMR for hydrogen production using a high-temperature gas-cooled reactor (HTGR), low reactant-gas inlet velocity, suitable inlet temperature, high inlet velocity, and a high HTGR outlet temperature of helium were preferable.

Maximum Hydrogen Production Rate Optimization for Tubular Steam Methane Reforming Reactor

2019 ◽  
Vol 17 (9) ◽  
Author(s):  
Penglei Li ◽  
Lingen Chen ◽  
Shaojun Xia ◽  
Lei Zhang
Keyword(s):  
Hydrogen Production ◽  
Production Rate ◽  
Inlet Temperature ◽  
Methane Reforming ◽  
State Variables ◽  
Hydrogen Production Rate ◽  
Steam Methane Reforming ◽  
Steam Methane ◽  
Tubular Reactors ◽  
Rate Optimization

Abstract The performance of a steam methane reforming (SMR) reactor is optimized by using the theory of finite time thermodynamics in this paper. The maximum hydrogen production rate (HPR) and the corresponding optimal exterior wall temperature (EWT) and the optimal pressure of the reaction mixture (PRM) profiles in the SMR reactor are obtained by using nonlinear programming method. In the optimization process, the fixed inlet mole flow rate of components, the thresholds of the state variables and the conservation equations are taken as the constraints. The performance of the optimal reactor is compared with that of the reference reactor with a linear EWT profile. The results show that the HPR of the optimal reactor increases by about 11.8 %. The optimal EWT profile is alike with the linear EWT profile. The HPR increases with the increase of the inlet temperature of reaction mixture and the decrease of the inlet PRM. The influence of the TRM on the HPR is smaller than that of the PRM. The results obtained herein are helpful to the optimal design of practical tubular reactors.

Comparative Analysis of Advanced H2/Air Cycle Power Plants Based on Different Hydrogen Production Systems From Fossil Fuels

2004 ◽  
Author(s):  
M. Gambini ◽  
M. Vellini
Keyword(s):  
Hydrogen Production ◽  
Power Plants ◽  
Fossil Fuels ◽  
Coal Gasification ◽  
Fossil Fuel ◽  
H2 Production ◽  
Combined Cycle ◽  
Methane Reforming ◽  
Steam Methane Reforming ◽  
Steam Methane

In this paper two options for H2 production by means of fossil fuels are presented, evaluating their performance when integrated with advanced H2/air cycles. The investigation has been developed with reference to two different schemes, representative both of consolidated technology (combined cycle power plants) and of innovative technology (a new advance mixed cycle, named AMC). The two methods, here considered, to produce H2 are: • coal gasification: it permits transformation of a solid fuel into a gaseous one, by means of partial combustion reactions; • steam-methane reforming: it is the simplest and potentially the most economic method for producing hydrogen in the foreseeable future. These hydrogen production plants require material and energy integrations with the power section, and the best connections must be investigated in order to obtain good overall performance. The main results of the performed investigation are quite variable among the different H2 production options here considered: for example the efficiency value is over 34% for power plants coupled with coal decarbonization system, while it is in a range of 45–48% for power plants coupled with natural gas decarbonization. These differences are similar to those attainable by advanced combined cycle power plants fuelled by natural gas (traditional CC) and coal (IGCC). In other words, the decarbonization of different fossil fuels involves the same efficiency penalty related to the use of different fossil fuel in advanced cycle power plants (from CC to IGCC for example). The CO2 specific emissions depend on the fossil fuel type and the overall efficiency: adopting a removal efficiency of 90% in the CO2 absorption systems, the CO2 emission reduction is 87% and 82% in the coal gasification and in the steam-methane reforming respectively.

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