Chemical-Looping Combustion of Biomass in a 10 kW_thReactor with Iron Oxide As an Oxygen Carrier

Abstract

Chemical-looping combustion of biomass was carried out in a 10 kW th reactor with iron oxide as an oxygen carrier. A total 30 h of test was achieved with the same batch of iron oxide oxygen carrier. The effect of the fuel reactor temperature on gas composition of the fuel reactor and the air reactor, the proportion of biomass carbon reacting in the fuel reactor, and the conversion of biomass carbon to CO 2 in the fuel reactor was experimentally investigated. The results showed that the CO production from biomass gasification with CO 2 was more temperature dependent than the CO oxidation with iron oxide in the fuel reactor, and an increase in the fuel reactor temperature produced a higher increase for the CO production from biomass gasification than for the oxidation of CO by iron oxide. Although the conversion of biomass carbon to CO 2 in the fuel reactor decreased with the increase of the fuel reactor temperature, there was a substantial increase in the proportion of biomass carbon reacting in the fuel reactor. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to characterize fresh and reacted oxygen carrier particles. The results showed that the transformation of Fe 2 O 3 to Fe 3 O 4 is the favored step in the process of iron oxide reduction with biomass syngas. The low reactivity of reacted oxygen carrier was mainly ascribed to the sintering grains on the particle surface. To restrain the surface sintering of oxygen carrier particles, an intensive oxidization of reduced oxygen carrier with air in the air reactor should be avoided in the process of oxygen carrier regeneration, and air staging should be adopted for the oxidization of reduced oxygen carrier with air in the air reactor.

Relevance of the coal rank on the performance of the in situ gasification chemical-looping combustion

“…Biomass as solid fuel was evaluated by Shen et al [32] in a continuous 10 kW th CLC combustor using an oxygen carrier prepared from iron oxide and CO 2 as gasification medium.…”

Chemical Looping Process - A Novel Technology for Inherent CO2 Capture

“…Steam in the inlet fluidizing stream can sufficiently gasify solid fuels for direct combustion to achieve over 95% of fuel conversion (Gao et al, 2008;Leion et al, 2007). Inlet fluidizing gas containing 100% steam was employed in a fluidized bed reactor system for coal combustion by NiO/NiAl 2 O 4 oxygen carrier, and 95% of CO 2 yield was achieved for operating temperatures above 900°C (Gao et al, 2008;Shen et al, 2009a). Since Ni-based oxygen carriers demonstrate great performance in reactivity, sulfur contained in solid fuels may react with nickel to form Ni 3 S 2 causing deactivation and bed agglomeration (Leion et al, 2009).…”

“…The combustion of hybrid poplar with Fe-based oxygen carriers in a moving bed reactor was simulated by ASPEN PLUS, the operating temperature in the fuel reactor should be above 900°C to achieve fully biomass conversion and nearly 100% of CO 2 yield (Li et al, 2010b). Pine sawdust contained 14.8% of fixed carbon and 75.8% of volatile compounds was combusted by chemical looping process with Fe-based oxygen carriers in a 10 kW th fluidized bed reactors, and achieved 95% of CO 2 yield at 920°C (Shen et al, 2009a).…”

“…Currently, fluidized bed and moving bed reactor systems are developed for the application of chemical looping process, depending on the Development of chemical looping technology is extremely rapid in last decade while tests of pilot scale reactors for thousands hour operation were proceeded in many countries around the world with various fuels, such as syngas, methane, natural gas, coal, petroleum coke and biomass (Mattisson et al, 2001;Leion et al, 2009;Shen et al, 2009a;Lyngfelt, 2011). The chemical looping reactors are suggested to substitute the conventional boilers for power generation, as illustrated in Fig.…”

Assessment of technological solutions for improving chemical looping combustion of solid fuels with CO2 capture

“…An increase in the solids circulation rate has a 18 significant effect, decreasing the oxygen demand in the oxygen carrier to fuel ratios  OC <5; 19 however, high  OC values are not recommended because the loss in CO 2 capture is too high [18]. 20 Previous studies showed that optimal operational conditions consisted of a temperature between 21 1000-1100ºC, an oxygen carrier to fuel ratio in the range of  OC = 1.2-5 and a solids inventory 22 within the region of 1000-2000 kg/MW th [18,35]. 23 O-2.…”