Low-cost syngas shifting for remote gasifiers: Combination of CO2 adsorption and catalyst addition in a novel and simplified packed structure

This paper presents the technical validation of a novel, low-complexity alternative based on the inclusion of a patented (IEPI-MU-2016-185) packed bed for improving the performance of remote, small-scale gasification facilities. This study was carried out in an updraft, atmospheric-pressure gasifier, outfitted with a syngas reflux line, air and oxygen feed, and an upper packed-bed coupled to the gasification unit to improve the syngas quality by catalytic treatment and CO2 adsorption. The experimental facility is located in the rural community San Pedro del Laurel, Ecuador. Gasification experiments, with and without packed material in the upper chamber, were performed to assess its effect on the syngas quality. The assessment revealed that the packed material increases the carbon monoxide (CO) content in the syngas outlet stream while carbon dioxide (CO2) was reduced. This option appears to be a suitable and low-complexity alternative for enhancing the content of energy vectors of syngas in gasification at atmospheric pressure since CO/CO2 ratios of 5.18 and 3.27 were achieved against reported values of 2.46 and 0.94 for operations which did not include the addition of packed material. It is concluded that the upper packed-bed is an active element able to modify syngas characteristics since CO2 content was reduce

Dynamic modelling of updraft gasifiers: Incidence of feedstock quality and operational variables in the transient model structure

This paper describes the definition of the transient model structure for an updraft gasifier and the input variables related to the process and the feedstock quality with the most significant influence on the dynamic models and the transient behaviour. For such purpose, a set of open-loop dynamics experiments were carried out in the gasifier. Moreover, the output variables performance was recorded together with the composition analysis of the municipal solid waste batch (MSW). The output and operational variables record was used as base information for performing regressions of transient models with the purpose of determining the model type choice that achieves the largest occurrence frequency of fitting percentage figures above 50%. In addition, the dataset of regression parameters is analysed through feature selection in order to establish the influence of feedstock quality parameters and independent dynamic operational variables in dynamic changes. The model structure selection determined that underdamped, second order with one zero transfer function (P2ZU) is the most accurate case for updraft gasifiers. Regarding the influence of feedstock-related information, feature selection results show that ultimate composition is the group of quality parameters with the most significant influence on transient behaviour. Results also show that recirculation flow rate is the operational variable whose effect in the output variables is the most likely to be predicted and potentially controlled. The results for this variable show that 64.3% of the performed regressions achieved a fitting percentage value above 50%

Syngas composition in atmospheric pressure gasifiers after a catalytic treatment

The current work describes the experimental results of the composition of syngas obtained from gasification of municipal solid waste (MSW). This particular study was carried out in an updraft, atmospheric-pressure, and pilot-scale gasifier. The gasifier is also outfitted with a gas reflux line, air and oxygen feed, and a catalytic packed-bed reactor coupled to the gasification unit in order to improve the syngas quality. Characteristics and operation variables related to the gas retention time along the gasifier and catalytic reactor are also mentioned and analyzed as part of the described study. The assessment was focused in increasing the carbon monoxide (CO) concentration in the outlet stream of syngas while the carbon dioxide (CO2) is reduced. Observed effects in other gaseous components of syngas are also mentioned . Preliminary results show the proposed alternative is able to increase the CO/ CO2 ratio in 30% in comparison with reported results of similar gasifiers. The described phenomenon appears as a suitable and low-cost alternative for enhancing the energy content and the content of energy vectors such as CO and hydrogen (H2) of syngas in gasification processes since high pressure conditions are avoided