Fountain confined conical spouted beds

Oxidative Fast Pyrolysis of High-Density Polyethylene on a Spent Fluid Catalytic Cracking Catalyst in a Fountain Confined Conical Spouted Bed Reactor

The oxidative fast pyrolysis of plastics was studied in a conical spouted bed reactor with a fountain confiner and draft tube. An inexpensive fluid catalytic cracking (FCC) spent catalyst was proposed for in situ catalytic cracking in order to narrow the product distribution obtained in thermal pyrolysis. Suitable equivalence ratio (ER) values required to attain autothermal operation were assessed in this study, i.e., 0.0, 0.1, and 0.2. The experiments were carried out in continuous regime at 550 °C and using a space-time of 15 g_catalyst min g_HDPE ^-1. The influence of an oxygen presence in the pyrolysis reactor was analyzed in detail, with special focus on product yields and their compositions. Operation under oxidative pyrolysis conditions remarkably improved the FCC catalyst performance, as it enhanced the production of gaseous products, especially light olefins, whose yields increased from 18% under conventional pyrolysis (ER = 0) to 30% under oxidative conditions (ER = 0.1 and 0.2). Thus, conventional catalytic pyrolysis led mainly to the gasoline fraction, whereas light olefins were the prevailing products in oxidative pyrolysis. Moreover, the oxygen presence in the pyrolysis reactor contributed to reducing the heavy oil fraction yield by 46%. The proposed strategy is of great relevance for the development of this process, given that, on one hand, oxygen cofeeding allows solving the heat supply to the reactor, and on the other hand, product distribution and reactor throughput are improved.

Solar Thermochemical Green Fuels Production: A Review of Biomass Pyro-Gasification, Solar Reactor Concepts and Modelling Methods

This paper addresses the solar thermochemical conversion of biomass or waste feedstocks based on pyro-gasification for the clean production of high-value and energy-intensive fuels. The utilization of solar energy for supplying the required process heat is attractive to lower the dependence of gasification processes on conventional energy resources and to reduce emissions of CO2 and other pollutants for the production of high-value chemical synthetic fuels (syngas). Using concentrated solar energy to drive the endothermal reactions further allows producing more syngas with a higher gas quality, since it has not been contaminated by combustion products, while saving biomass resources. The solar-driven process is thus a sustainable and promising alternative route, enabling syngas yield enhancement and CO2 mitigation, thereby potentially outperforming the performance of conventional processes for syngas production. This review presents relevant research studies in the field and provides the scientific/technical knowledge and background necessary to address the different aspects of the solar gasification process. An overview of the available solar concentrating technologies and their performance metrics is first introduced. The solar gasifier concepts and designs that were studied from lab to industrial scale are presented, along with their main benefits and limitations. The different management strategies proposed to deal with solar energy variations are also outlined, as well as the major pilot-scale applications and large-scale system level simulations. A specific emphasis is provided on the spouted bed technology that appears promising for the gasification process. Finally, the main modeling approaches of pyro-gasification and kinetics for simulation of gasifiers are described. This study thus provides a detailed overview of the efforts made to enhance the thermochemical performance of solar-assisted biomass gasification for synthetic fuel production.

On the pyrolysis of different microalgae species in a conical spouted bed reactor: Bio-fuel yields and characterization

The aim of this work was to study fast pyrolysis of three microalgae species in a continuous bench-scale conical spouted bed reactor at 500 °C. Bio-gas, bio-oil and bio-char yields have been determined and characterized by using GC, GC/MS, elemental analyzer and SEM. Bio-oil was the main product obtained through pyrolysis of microalgae. The non-condensable gaseous stream is made up of mainly hydrogen, carbon monoxide and carbon dioxide, apart from other light hydrocarbons detected in lower concentration, as are methane, ethane, ethylene, propane and propylene. The compounds identified in the bio-oil have been categorized into hydrocarbons, nitrogen containing compounds, ketones, alcohols, acids, lactones, phenols and aldehydes. The nitrogen and carbon contents of the microalgae bio-chars are higher than those for bio-chars derived from other biomasses. Pyrolysis improved the morphology and porous structure of microalgae. Finally, the mechanism involving microalgae pyrolysis has been approached and the main reaction pathways have been proposed.

Hydrodynamics, numerical study and application of spouted bed

This article reviews the major research and development on spouted beds (SBs). Due to its unique structural and flow characteristics, the SB is a very successful system in most applications. Two-phase and sometimes three-phase interactions generate a large number of variables to be noted in each process. Up-to-date information on the fundamentals and applications of SBs has been briefly presented, based on the published works. Thousands of interesting studies on hydrodynamic characteristics, numerical simulations, and new applications of SBs are reported. In the first step, the present work presents a review of hydrodynamic characteristics (circulation of solids in SB, measurement techniques for particle tracking and empirical hydrodynamics, pressure drop, maximum spoutable height, minimum spouting velocity, and diameter of the spout). In the second step, main mathematical models and computational fluid dynamics (CFD) simulation of the SB to predict and analyze different processes are described. Some main mathematical modeling and the recent advances of two fluid methods and discrete element method approaches in CFD simulation of SBs are summarized. In the last step, some new applications of the SB are presented. As the result of this review, we can observe the importance of further development of hydrodynamics structure, working on modeling and related correlations and improve the applications of SBs.