•Characteristics of microalgae gasification using chemical looping were investigated.•Fe2O3 as oxygen carrier made gasification efficiency elevate from 61.65% to 81.64%.•Iron-steam reaction played a key role in H2 production in microalgae CLG.As a novel gasification technology, chemical looping gasification (CLG) was considered as a promising technology in solid fuel gasification. In this work, CLG was applied into microalgae, and the characteristics of syngas production and oxygen carrier in the presence of steam were obtained through experiments in a fixed bed reactor. The results showed that the partial oxidation of oxygen carrier improved the gasification efficiency from 61.65% to 81.64%, with the combustible gas yield of 1.05 Nm3/kg, and this promotion effect mainly occurred at char gasification stage. Also, an optimal Fe2O3/C molar ratio of 0.25 was determined for the maximum gasification efficiency. 800 °C was needed for the gasification efficiency over 70%, but excess temperature caused the formation of dense layer on oxygen carrier particle surface. Steam as gasification agent promoted syngas production, but excess steam decreased the gasification efficiency. Steam also enhanced the hydrogen production by the conversion of Fe/FeO into Fe3O4, avoiding the intensive reduction of oxygen carrier. The Fe2O3 oxygen carrier maintained a good reactivity in 10th cycle while used for microalgae CLG. The results indicated that CLG provided a potential route for producing combustible gas from microalgae.

•The co-combustion of sewage sludge and oil shale was investigated by TGA system.•The DSC and TG experiments were used for non-isothermal kinetics analysis.•The average activation energy reached the minimal by blending 10% sewage sludge.•The global thermal process of co-combustion was modeled by the DAEM.The co-combustion behaviors between sewage sludge and oil shale were investigated in this study. The TGA experiment was given a temperature spanning from 105 °C to 1000 °C by setting the heating rates 10, 20 and 30 °C/min. The combustion characteristics, characteristic index, co-combustion interactions, activated energy and DAEM of blends were studied in this paper. The ignition temperature shifted to an earlier temperature when adding sludge. An inhibition interaction of co-combustion occurred at low temperature and the proportion of sludge with 10% showed the best promoting effects. The average activated energy reached the minimal also when the ratio of sludge was 10%. The average fractional residuals were less than 1.3%. Models showed a good recuperation with experimental data.

•Gauss-Lorentz Amplitude function was adopted to the FTIR fitting analysis.•The evolution of six typical pyrolysis products were illustrated by TG-FTIR.•Contents of five possible products for mixture pyrolysis were analyzed via Py-GCMS.•The contents of NH3, HCN, acid, furfural and C7# reduced in co-pyrolysis.In this paper, the pyrolysis process of mixed samples, bagasse with the addition of sludge, were investigated by TG-FTIR, and Py-GC/MS. For the mixed samples, the proportions of sludge were 10%, 30% and 50%. With the sludge ratio increased, the initial temperature and the terminated temperature increased. Eleven chemical structure groups were resolved from both of bagasse and sludge by KBr-Tabletting based FTIR analysis. Aromatic compounds, CO2, CO, CO, NH3 and HCN were the major gaseous products surveyed from the TG-FTIR inspection. The percentage of pyrolysis products (acetic acid, C7#, furfural, benzene derivatives, C7P) were figured out from Py-GC/MS analysis. The addition of sludge was beneficial for the production of group C7P, whose carbon atoms exceeded 7. This research provided useful background knowledge for co-pyrolysis of bagasse and sewage sludge.Download high-res image (77KB)Download full-size image

Potassium, a key nutrient involved in biomass growth, contributes to problematic ash fouling and slagging during combustion. This study was conducted to investigate the combustion behavior of typical rice straw grown in south China, as well as potassium transformation and evolution behaviors. The results showed that the volatile components of the straw have good devolatilization and combustion characteristics, while the residual char is relatively slow to burn out. Under low-temperature conditions, the combustion of char beginning after the devolatilization is almost complete. Chlorine has a higher volatility than alkali metals under combustion conditions. In addition, the migration of potassium has the same tendency as the release of volatiles, indicating that some potassium might evolve together with volatiles at the initial stage of combustion, i.e., in the form of organic potassium. Above 500 °C, more inorganic potassium is released to the gas phase, primarily as KCl. These results imply that low-temperature combustion is effective for the retention of potassium within straw ash. A high silica content in straw material is also helpful to constrain inorganic potassium within the biomass residual but might induce agglomeration of the straw ash.

•Pyrolysis profiles of ABS/PVC, ABS/PA6 and ABS/PC were investigated using TG-FTIR.•ABS made PVC pyrolysis earlier and HCl emission slightly accelerated.•The interactions could be attributed to the intermolecular radical transfer.•CaCO3 made the pyrolysis products from PA6 and PC further decomposed into CO2.As important plastic blends in End-of-Life vehicles (ELV), pyrolysis profiles of ABS/PVC, ABS/PA6 and ABS/PC were investigated using thermogravimetric-Fourier transform infrared spectrometer (TG-FTIR). Also, CaCO3 was added as plastic filler to discuss its effects on the pyrolysis of these plastics. The results showed that the interaction between ABS and PVC made PVC pyrolysis earlier and HCl emission slightly accelerated. The mixing of ABS and PA6 made their decomposition temperature closer, and ketones in PA6 pyrolysis products were reduced. The presence of ABS made PC pyrolysis earlier, and phenyl compounds in PC pyrolysis products could be transferred into alcohol or H2O. The interaction between ABS and other polymers in pyrolysis could be attributed to the intermolecular radical transfer, and free radicals from the polymer firstly decomposed led to a fast initiation the decomposition of the other polymer. As plastic filler, CaCO3 promoted the thermal decomposition of PA6 and PC, and had no obvious effects on ABS and PVC pyrolysis process. Also, CaCO3 made the pyrolysis products from PA6 and PC further decomposed into small-molecule compounds like CO2. The kinetics analysis showed that isoconversional method like Starink method was more suitable for these polymer blends. Starink method showed the average activation energy of ABS50/PVC50, ABS50/PA50 and ABS50/PC50 was 186.63 kJ/mol, 239.61 kJ/mol and 248.95 kJ/mol, respectively, and the interaction among them could be reflected by the activation energy variation.