Gasification characteristics and synergistic effects of typical organic solid wastes under CO2/steam atmospheres.

Gasification technology is an effective way to achieve efficient, safe, and resourceful disposal of organic solid wastes (OSWs). Due to the complex sources and variable components of the OSWs, the co-disposal is highly essential. Various typical OSWs, including food waste (cooked rice, CR), agricultural waste (rice husk, RH; sugarcane bagasse, SB), and industrial waste (furfural residue, FR), were selected for this study. The gasification characteristics and synergistic performance were examined in terms of thermal weight loss characteristics under the CO2 atmosphere and gaseous product characteristics under the steam atmosphere. The synergistic indices of performance parameters were introduced to quantify the synergistic effects. The gasification activity of FR was remarkably higher than that of other OSWs. In the co-gasification with CR under the CO2 atmosphere, FR played an excellent positive synergistic effect, but the agricultural wastes played a slight or no synergistic effect. In the steam co-gasification, RH, SB, and FR all promoted the generation of syngas, in which FR showed still significant synergistic effects, with the synergistic indices of H2 yield, syngas yield, CCE, and CGE being 4-12 times higher than those of other blended wastes. The excellent performance of FR in (co-)gasification was mainly attributed to the acidic properties of FR, which was confirmed by comparing the (co-)gasification performance of FR with and without water-washing pretreatment. The work provides guidance for the co-disposal of OSWs in industrial applications.

In-situ pyrolysis kinetic analysis and fixed-bed pyrolysis behavior of ex-service wind turbine blades.

After the peak of rapid wind power development, a large amount of wind turbine blades reach/exceed their service life due to aging or damage. These ex-service wind turbine blades (EWTB) will increase the issue of its high-efficient utilization in the future decades. Among several treatment methods, pyrolysis has been considered as a promising solution to separate inorganic fiberglass and make organic epoxy resin (OER) high-value-added converted. However, the pyrolysis mechanism, chemical composition, and fiberglass separation of EWTB have not been deeply studied. In this paper, the synthetic model compound of epoxy resin was firstly used to investigate the thermal weight loss and pyrolysis kinetics, the thermal weight loss temperature range of which was 300 âˆ¼ 480 °C. The apparent activation energy was minimum when the conversion rate was 0.6, and the pyrolysis mechanism was determined by the Coats-Redfern method as a diffusion control. On this basis, a lab-scale fixed-bed was conducted to study fast-heating pyrolysis characteristics of EWTB. It could be analyzed that the chemicals in the pyrolytic liquid were a series of phenolics with methyl and vinyl substituted benzene rings (e.g., bisphenol A, p-isopropenyl phenol, and phenol). Bisphenol A presented a relatively high selectivity of 51.02%, which could be recycled as the main raw material for the synthesis of epoxy resins. Furthermore, clean fiberglass could be separated by combusting the residual carbon in pyrolytic solids. These results might be useful for achieving the separation and resource utilization of organic and inorganic components of EWTB.

(Co-)gasification characteristics and synergistic effect of hydrothermal carbonized solid/liquid products derived from fresh kitchen waste.

Kitchen waste has high moisture and rich organics, which can be transformed into hydrochar by hydrothermal carbonization (HTC) and then used for gasification efficiently. But process water (liquid product from HTC, containing organic compounds) has not been well utilized in the way of thermochemistry. In this study, a scheme of co-gasification of solid and liquid products of kitchen waste HTC process was proposed, and the separate gasification and co-gasification were studied. The results showed that after HTC process, the obtained hydrochar size became smaller and uniform, and the high heating value increased from 19.90 MJ/kg to 28.03 MJ/kg. The carbon skeleton of hydrochar was mainly composed of aromatic and alkyl C, which was easily converted into coke during gasification. Process water mainly contained pyrazine organics, and its C and N content were 18.94 g/L and 3.25 g/L, respectively. The co-gasification syngas yield of solid and liquid products was significantly higher than the calculated total yield of separate gasification. There was obvious synergistic effect in the coke co-gasification stage, and the H2 production was 1.24 times of the calculated value. Synergistic effect was mainly caused by the introduction of process water, which contained 785.82 mg/L of K and would catalyze the coke co-gasification. HTC coupled with co-gasification is an efficient disposal for kitchen waste with high moisture.

The influence of a two-step leaching pretreatment on the steam gasification properties of cornstalk waste.

Knowing the effect of specific alkali and alkali earth metals forms is vital for the high-efficient gasification of biomass. This work developed a two-step leaching method to pretreat cornstalk, dividing the inorganic metals into water-soluble (K+, 74 wt%), acid-soluble (Al3+, Ca2+, Fe2+, etc) and insoluble (Si4+) substances. The water-soluble K+ was mainly in KCl form, the acid-soluble metals were removed in phosphates and sulfates forms. The rapid gasification properties of raw material, water leaching residue and acid leaching residue indicated that KCl was the key factor to enhance the hydrogen yield and gasification efficiency. Apart from K+, the alkali earth metals (Ca2+, Mg2+) also had a little catalytic effect on producing hydrogen. When the feedstock was out of metal cations, the syngas was mainly composed of CO. The basic ions to acid ions ratio was linearly related to the syngas quality, which could conduct the flux additives.

On-line analysis of the correlation between gasification characteristics and microstructure of woody biowaste after hydrothermal carbonization.

Woody biowaste is a component which is difficult to be converted among multiple solid waste (MSW) during the hydrothermal carbonization (HTC). In this paper, poplar sawdust was pretreated by HTC to study the correlation between microstructure and gasification characteristics. The results showed the fixed carbon and higher calorific value increased from 13.44 % and 19.41 MJ/kg to 41.47 % and 25.85 MJ/kg after HTC, respectively. The cold gas efficiency of hydrochars prepared at 220 °C was the highest of 93.57 % compared with that of raw material of 76.65 %. It was found that carbon structure had a greater influence on hydrochars gasification characteristics than pore structure. The crystallinity of hydrochars had a good correlation with the total yield and H2/CO of syngas, which can provide guidance for HTC pretreatment of woody biowaste and MSW.