Internally-circulating Fluidized Bed Reactor Using Thermal Storage Material for Solar Coal Coke Gasification

Abstract

A windowed reactor prototype of internally-circulating fluidized bed is tested and demonstrated at laboratory scale for steam gasification of coal coke irradiated directly by concentrated Xe light from a 3-kW th sun simulator. The bed material is composed of particle mixture of coal coke and quartz sand. A coal coke of the bed material works as a carbonous feedstock, while quartz sand functions as a thermal storage/transfer medium inside the reactor. The fluidized bed reactor, having a transparent window due to incoming radiation of concentrated solar beam on the ceiling of the reactor, is designed to be combined with a solar reflective tower or beam-down optics. A potential of quartz sand in the internally-circulating fluidized bed reactor is evaluated for steam gasification of coal coke by gasification performance (CO, H 2 and CO 2 production rates, carbon conversion, and lightto-chemical efficiency). The gasification performances for use of the particle mixture in the reactor are compared with that for use of coal coke particle. The fluidized bed of a particle mixture including coal coke and quartz sand was gasified at lower temperature with a higher rate in comparison to that of a coal coke. Furthermore, a use of smaller and lighter coal coke particles were easily converted to gaseous species due to larger surface area as well as the gasification rates.

Solar-hybrid Thermochemical Gasification of Wood Particles and Solid Recovered Fuel in a Continuously-Fed Prototype Reactor

“…It showed promising results with more than 20% of the incoming sunlight effectively stored as fuel calorific value in the product gas. Since then, other reactor designs, including packed beds [20,25], fluidized beds [18,26], spouted beds [15,27], vortex flow [21,28], drop tube [16,29], and molten salt [10,30] reactors were tested to convert a wide variety of feedstocks such as biomass, coal and different kinds of waste with either steam or CO 2 as an oxidizing agent. Recent exploratory work on hybrid solar gasification makes use of O 2 as a means to maintain the process temperature during sun-lacking periods thanks to combined solar heating and in-situ oxy-combustion [31][32][33][34].…”

Analysis of Solar Steam Gasification of Carbon- Rich Fly Ash to Produce Synthetic Gas.

“…This heat transfer limitation of the bed was responsible for low performance of the solar fluidized bed reactor. To overcome this problem, the group has proposed the concept of an internally circulating fluidized bed reactor (12)(13)(14).…”

Design and demonstration of a prototype 1.5 kWth hybrid solar/autothermal steam gasifier

“…Directly-irradiated fluidized beds for http://dx.doi.org/10.1016/j.fuel.2017.09.059solar gasification of coal, cokes, and cellulose have been explored in literature [12,[21][22][23][24][25][26][27][28]. One drawback of fluidized-bed designs compared to packed beds is that small, relatively uniform feedstock particles are required, translating to costlier feedstock preparation.…”

“…Prominent solar-driven gasifier designs that have been examined in literature have employed entrained flow [11,16,18], drop tubes [7,8,10], packed beds [15,19,20], and fluidized beds [12,[21][22][23][24][25][26][27][28]. Entrained-flow and drop-tube gasifiers generally have very short residence times while benefiting from enhanced heat and mass transfer.…”