Design and Operations of a 15 kW_th Subpilot Unit for the Methane-to-Syngas Chemical Looping Process with CO₂ Utilization

Abstract

The methane-to-syngas (MTS) chemical looping process is an advanced methane reforming technology for the production of high purity syngas. The developed MTS process utilizes metal oxide oxygen carriers in a cocurrent moving bed reactor to partially oxidize the methane such that the resulting syngas stream is undiluted by nitrogen in air or H2 from overconversion and directly suitable for downstream processing. The oxygen carriers are regenerated with air in a separate fluidized bed reactor producing a spent air stream separate from the product syngas, circumventing the need for cryogenic air separation units. In this work, a 15 kWth subpilot unit is designed and operated in a continuous manner to experimentally confirm the viability of the MTS process. Reactor design considerations and methodology are discussed in detail. An iron–titanium composite oxygen carrier is used as the oxygen carrier for its ability to achieve high methane conversion while regulating the product syngas to the partial oxidation products, CO and H2. Syngas is produced with an H2/CO ratio of ∼2, and a purity of ∼97% is produced with methane conversion exceeding 99%. The coinjection of methane with H2 and/or H2O is explored for the purpose of H2 utilization and flexible H2/CO ratios, allowing the MTS process to produce syngas for a variety of downstream processes without reactor modification. The results indicate that syngas with H2/CO ratios ranging from 1.19 to 2.50 with high methane conversion and syngas purity can be produced with coinjection. No evidence of carbon deposition on the oxygen carrier is revealed, and the oxygen carrier retained structural integrity after subjection to reaction and circulation in the subpilot unit.

CO2 Capture and Utilization Editorial

“…A cocurrent moving-bed reactor loaded with an iron−titanium oxygen carrier is able to partially oxidize methane to syngas containing H 2 /CO ratios of ∼2, while almost complete fuel conversion and negligible carbon deposition are achieved. 32 CO-rich gas can be produced by means of reverse water−gas shift of mixtures of CO 2 /H 2 using spinel-structured ternary ferrites. 33 Pure H 2 can be obtained by means of water-splitting CLC of natural gas.…”

“…Chemical looping technology can also be adapted for the production of H 2 or syngas with inherent CO 2 capture. A cocurrent moving-bed reactor loaded with an iron–titanium oxygen carrier is able to partially oxidize methane to syngas containing H 2 /CO ratios of ∼2, while almost complete fuel conversion and negligible carbon deposition are achieved . CO-rich gas can be produced by means of reverse water–gas shift of mixtures of CO 2 /H 2 using spinel-structured ternary ferrites .…”

Thermodynamic Investigation of Process Enhancement in Chemical Looping Reforming of Methane through Modified Ca–Fe Oxygen Carrier Utilization

“…Although the H 2 /CO ratio is an important parameter in the syngas-generating systems, it is not being considered here as more emphasis is laid on the overall process improvement by changing the oxygen carrier. The H 2 /CO ratio can be manipulated through steam addition as per process requirement . For all exergy calculations, the reference temperature and pressure of 25 °C and 1 atm, respectively, are used.…”

“…The H 2 /CO ratio can be manipulated through steam addition as per process requirement. 14 For all exergy calculations, the reference temperature and pressure of 25 °C and 1 atm, respectively, are used. Physical exergy of the streams is calculated using Aspen, whereas thermochemical exergy is calculated using the values given in Table S3.…”

“…The work performed here aims to explore the use of The Ohio State University’s novel cocurrent moving bed reducer for syngas production. , In this design, fully oxidized oxygen carriers and methane are injected into the reactor at the top and allowed to move downward cocurrently. In this process, methane reacts with the oxygen carriers to produce syngas and exits the reactor outlet in equilibrium with reduced oxygen carriers.…”