Hydrogen by sorption enhanced methane reforming: A grain model to study the behavior of bi-functional sorbent-catalyst particles

3D Simulation of bubbling fluidized bed reactors for sorption enhanced steam methane reforming processes

Process simulations of blue hydrogen production by upgraded sorption enhanced steam methane reforming (SE-SMR) processes

ABSTRACTA 1 m high laboratory‐scale and a 4 m high industrial‐scale sorption‐enhanced steam methane reforming (SE‐SMR) fluidized bed reactor were simulated using a three‐fluid model. The performance of the SE‐SMR process was compared with the steam methane reforming (SMR) process. The influences of the superficial gas velocities and the solid loading (packed bed heights) on the reactor performance (hydrogen purity) were studied. The simulation results show that a higher purity of the hydrogen product can be obtained in a SE‐SMR reactor. The superficial gas velocity is an important parameter. In the present study, it has been found that the binary sorbent‐catalyst particles are well mixed when the bed is operated at m/s. The sorbent can adsorb CO steadily, thus the dry mole fraction of the hydrogen product can get above 0.95 in the 1 m laboratory‐scale bed, and above 0.97 in the 4 m industrial‐scale bed. However, when the laboratory scale bed is operated at a lower superficial gas velocity of m/s, the binary sorbent‐catalyst particles are segregated. When the bed is operated at a higher superficial gas velocity of 0.3 m/s, the process work load is increased, and the gas residence time in the reactor is decreased. Therefore, the hydrogen product purity is further decreased. The simulation results also show that there is an optimal bed height limit for the 4 m industrial‐scale bed, at which further increase of the packed bed height cannot increase the hydrogen purity.

A three-dimensional (3D) Eulerian two-fluid model with an in-house code was developed to simulate the gas-particle two-phase flow in the fluidized bed reactors. The CO2 capture with Ca-based sorbents in the steam methane reforming (SMR) process was studied with such model combined with the reaction kinetics. The sorption-enhanced steam methane reforming (SE-SMR) process, i.e., the integration of the process of SMR and the adsorption of CO2, was carried out in a bubbling fluidized bed reactor. The very high production of hydrogen in SE-SMR was obtained compared with the standard SMR process. The hydrogen molar fraction in gas phase was near the equilibrium. The breakthrough of the sorbent and the variation of the composition in the breakthrough period were studied. The effects of inlet gas superficial velocity and steam-to-carbon ratio (mass ratio of steam to methane in the inlet gas phase) on the reactions were studied. The simulated results are in agreement with the experimental results presented by Johnsen et al. (2006a, Chem Eng Sci 61:1195–1202).

Reformed gas made by the steam methane reforming(SMR) process is used as fuel feed to MCFC, but it is not as good as pure hydrogen due to the presence of CO2 and CO. The sorption-enhanced steam methane reforming(SE-SMR) process can reduce CO2 and CO to a low level and produce high purity hydrogen. Considering the merits of similar operating temperatures (about 500°C) and carbon dioxide recycle, a novel concept of a six-step sorption-enhanced steam methane reforming (SE-SMR) combined with electricity generation by molten carbonate fuel cell (MCFC) is proposed. In the present paper, a cycle of the SE-SMR process, which include the steps of reaction/adsorption, depressurization, gas purges (nitrogen and reformed gas, respectively), and pressurization with reformed gas, is modeled and analyzed. The process stream in the SE-SMR process is used as anode feed in MCFC. According to the result of numerical simulation, a fuel cell grade hydrogen product (above 80% purity) at the SE-SMR temperature of 450°C can be obtained. A carbon dioxide recycle mechanism is developed for cathode feed of MCFC from flue gas by burning with excess air to achieve a proper CO2/air ratio (about 30:70). The novel electricity generation system, which can operate at lower energy consumption and high purity hydrogen feed is helpful for the MCFC'S performance and life time.

Reactor performance optimization by the use of a novel combined pellet reflecting both catalyst and adsorbent properties

Development of Al-stabilized CaO–nickel hybrid sorbent–catalyst for sorption-enhanced steam methane reforming

Advancements in sorption-enhanced steam reforming for clean hydrogen production: A comprehensive review

Techno-economic analysis of low-carbon hydrogen production by sorption enhanced steam methane reforming (SE-SMR) processes

Sorption enhanced catalytic Steam Methane Reforming: Experimental data and simulations describing the behaviour of bi-functional particles

Phase transition Ni-Co-Ca-O bifunctional catalysts for high and stable hydrogen production from sorption enhanced steam methane reforming

Alternative generation of H 2, CO and H 2, CO 2 mixtures from steam—carbon dioxide reforming of methane and the water gas shift with permeable (membrane) reactors

In this work, the sorption-enhanced steam methane reforming (SE-SMR) in which the integration of steam reforming reaction and carbon dioxide removal can be carried out in a single step was investigated in the thermodynamics aspects by using AspenPlusTM. Thermodynamics analysis was performed on both conventional steam methane reforming (SMR) and sorption-enhanced steam methane reformingprocesses based on minimization of Gibbs free energy method to determine the favorable operating conditions of each process. The effects of operating conditions (i.e., pressure, temperature and steam to carbon ratio) on hydrogen production were examined. The simulation results show that the optimal steam to carbon ratio is 6 and 5 for SMR and SE-SMR process, respectively. For SMR process, the maximum hydrogen purity of 78 % (dry basis) can be obtained at 950 K. While, the SE-SMR process offers two advantages over SMR process: (1) higher purity of hydrogen product can be achieved to 99 % (dry basis) and (2) required operating temperature is lower in the range of 700-850 K which is 100-150 K lower than SMR process, indicating that the SE-SMR process is less requirement of energy consumption.

Catalytic performance of Ni/CaO-Ca5Al6O14 bifunctional catalyst extrudate in sorption-enhanced steam methane reforming

Numerical Investigation of the Sorption Enhanced Steam Methane Reforming in a Fluidized Bed Reactor