• Energy Research

Tar formation resulting during lignocellulosic biomass gasification is a major impediment to utilizing biomass energy sources, in that it blocks and fouls the processing equipment; as such, any tar present in the produced syngas much be effectively removed. This study analyzes the ability of commercially available Ni and Ru based CH4 reforming catalysts to effect tar removal and compares deactivation characteristics. Toluene was used as the model biomass tar at concentrations of 30 and 100 g/Nm3. Several additional parameters were also tested, including reaction temperatures (400–800 °C), space velocities (5000–30,000 h−1), and the steam/toluene ratios (2–20). The variation of toluene conversion and product gas composition with reaction conditions was analyzed. Overall, H2 and CO production were favored by the Ru catalyst and generally increased with temperature. Conversion also increased with temperature, with conversions higher than 90% obtained at 800 °C.

Abstract Converting rice husk into energy is a promising method of generating renewable energy and reducing greenhouse gas emissions. The characteristics of rice husk gasification were investigated at an equivalence ratio (ER) of 0.20–0.35 and a gasifier temperature of 700–850 °C in a 20-tons-per-day (TPD) bubbling fluidized-bed gasifier system. The optimal conditions of the gasification operation were an ER of 0.20 and gasifier temperature of 800 °C. The low heating value of the gas product and cold gas efficiency were 1373.18 kcal/Nm3 and 70.75%, respectively. After passing the generated gas through the gas cleaning units, it was confirmed that the tar in the product gas was removed with an efficiency of 98%. The cleaned product gas was used for the operation of 400 kWe gas engine. Pressure loss often occurred at the bottom of the gasifier during the gasification operation; we found that the agglomerates generated by the gasification process caused it. Computational particle fluid dynamics simulations were performed to investigate the fluidizing characteristics of agglomerates. To prevent the pressure loss caused by the agglomerates, the stable control of temperature inside the gasifier is needed and an ash removal device remove agglomerates should be installed to maintain stable long-term operation.

A novel process has been developed at KIER (Korea Institute of Energy Research) for upgrading extra-heavy oil fractions. This process uses a rapid thermal pyrolysis (RTP) of extra-heavy oil with a gasifier/combustor of RTP residue to produce syngas as well as to supply heat to the pyrolyzer. Unreacted carbon in RTP residues from the pyrolyzer are used as a feedstock to the gasifier/combustor. The RTP residue is mostly sand with 1 wt % of petroleum coke.The possibility that product gas from the gasifier/combustor can supply heat to the pyrolyzer is examined. A continuous fluidized bed reactor with the maximum capacity of 10 kg/h (0.05 m I.D. × 1.2 m high) was designed and constructed for RTP residue gasification/ combustion. Air, oxygen, and steam were used as gasifying agents. The results of gasification are evaluated, including product gas composition, carbon conversion, gas yield, and heating value of the product gases. In air-blown gasification, the HHV (higher heating value) of the product gas ranges from 72.3 to 303.2 kcal/m 3 , which is lower than that of typical gasification. The carbon conversion is below 0.37, due to the low reactivity of petroleum coke and the diluting effects of nitrogen. In contrast, carbon conversion was greater than 0.93 with a higher equivalence ratio (ER = 1.0) in the O2-blown gasification mode. Product calorific values of up to 3739 kcal/m 3 can be obtained, with the steam serving as a gasifying agent.

Abstract Entrained-flow gasifiers used in commercial integrated gasification combined cycles are usually oxygen-blown. However, oxygen-blown gasification system is expensive to install and operate due to the equipment involved in oxygen purification and supply. To resolve this issue, this study mixed air and oxygen to perform coal gasification. An entrained-flow gasifier of 1 T/D scale was used with the coal water mixture as feedstock. Gasification was carried out at a temperature range of 970–1220 °C, an equivalence ratio of 0.25–0.62, and an air/O 2 ratio of 2.17–9.0. With an increasing gasification temperature, the amount of CO in the syngas increased while CO 2 and CH 4 decreased. Carbon conversion and cold gas efficiency continued to increase with the gasification temperature. In the equivalence ratio test, cold gas efficiency reached 52.1% at around 0.53 before decreasing under a fixed air flow rate of 90 N m 3 /h. By performing gasification with a varying air/O 2 ratio after fixing the flow rate, the influence of the equivalence ratio was examined. In addition, the influence of the flow rate was observed through changes in the air/O 2 ratio of the gasification agent with fixing the equivalence ratio. The maximum carbon conversion and cold gas efficiency were 90.7 and 57.7%, respectively, and the optimal air/O 2 ratio fell in the range of 2.86–3.1.

Abstract The pyrolysis characteristics of GFRP (Glass Fiber Reinforced Plastic), which is a thermosetting plastic composed of glass fibers and polymer compounds, were determined under non-isothermal conditions while heating at 5–20 °C/min from 500 to 900 °C using a thermo-gravimetric analyzer (TGA) and a batch-type pyrolyzer. The kinetic parameters for the GFRP were derived from the Freedman method with resultant activation energy ranging from 41.4 kJ/mol to 78.4 kJ/mol. The main components of the product gases were carbon monoxide from the ether and carbonyl decomposition of polymer and hydrogen from the aromatic ring breakage. The structural variations in the GFRP char were determined using BET, SEM, and FT-IR techniques. The surface area of GFRP char exhibited its maximum value at 600 °C, decreasing at higher temperatures with the collapsing macro-pore structure. The decomposed portion of the polymers attached to the glass fiber increased when increasing the temperature from SEM image. These data are useful for understanding the GFRP pyrolysis and gasification processes.

Abstract Herein, we describe the design and operation of an indirect coal liquefaction plant with integrated coal-water slurry manufacturing, entrained flow gasification, Rectisol, and Fischer–Tropsch processes to produce liquid fuels for vehicles. The above plant contained an entrained flow gasifier (10 t/d test rig) operated using oxygen as a gasifying agent (21 bar, 1100 °C) and could stably produce synthesis gas (37.8 vol% H2, 36.4 vol% CO) at 600 Nm3/h. Due to the importance of impurities in synthetic liquid fuel production, more than 99% of H2S contained in synthesis gas was removed by the Rectisol process employing refrigerated methanol. An iron-based catalyst allowed liquid fuels containing wax, light/heavy oil, and alcohol fractions to be obtained by the Fischer–Tropsch process at a rate of 5 barrel per day, with detailed analysis confirming their compliance with various quality standards and thus their suitability for use as automobile diesel after distillation.

The effects of plasma power (1–1.8 kW), oxygen/fuel (0–2.5) and steam/fuel ratios (0–1) on the gasification characteristics of glass fiber-reinforced plastic (GFRP) wastes have been determined in a microwave plasma reactor. GFRP, which is thermosetting plastic composed of glass fibers embedded within a polymer matrix, was used as an experimental sample. While carbon conversion increased with oxygen/fuel ratio, syngas heating value and cold gas efficiency decreased with oxygen supply due to the onset of combustion. With increasing steam/fuel ratio, water-gas shift and ion-reforming reaction favored higher concentration of H2. Increasing the plasma power was found to promote the conversion of carbon dioxide to carbon monoxide. The char surfaces of GFRP that were subjected to variable power and oxygen supplies were analyzed by scanning electron microscopy.

Abstract Biomass combustion in the oxy-fuel circulating fluidized bed is a promising technology to maximize the negative carbon dioxide emission and reduce pollutants emission in power plants. However, biomass ash related behaviors under oxy-combustion with kaolin additives still lack sufficient information. In this study, kaolin was used as an additive to manage ash problems during oxy-biomass combustion in a 0.1 MWth circulating fluidized bed combustion facility. Kaolin was fed at ratios of kaolin/wood pellet (wt./wt.): 0.21 and 0.25 by separately feeding or pre-mixing, respectively. The sampled ashes were characterized using X-ray fluorescence and X-ray diffraction analysis. Additionally, the potassium capture performance, slagging and fouling indices, attrition characteristics, and strength were also evaluated. The results revealed that potassium capture performance was improved by up to 24% at the ratio of kaolin/wood pellet (0.25) and kalsilite (KAlSiO4) within ash increased by adsorption on the metakaolin surface of gaseous potassium. The fouling formation decreased from 0.43 without kaolin to 0.07–0.15 with kaolin. In terms of oxy-fuel operation, SO2 emission was decreased when kaolin used, performing a high CO2 concentration of over 93 vol% and combustion efficiency of over 99%.

The global demand for masks has increased significantly owing to COVID-19 and mutated viruses, resulting in a massive amount of mask waste of approximately 490,000 tons per month. Mask waste recycling is challenging because of the composition of multicomponent polymers and iron, which puts them at risk of viral infection. Conventional treatment methods also cause environmental pollution. Gasification is an effective method for processing multicomponent plastics and obtaining syngas for various applications. This study investigated the carbon dioxide gasification and tar removal characteristics of an activated carbon bed using a 1-kg/h laboratory-scale bubble fluidized bed gasifier. The syngas composition was analyzed as 10.52 vol% of hydrogen, 6.18 vol% of carbon monoxide, 12.05 vol% of methane, and 14.44 vol% of hydrocarbons (C2-C3). The results of carbon dioxide gasification with activated carbon showed a tar-reduction efficiency of 49%, carbon conversion efficiency of 45.16%, and cold gas efficiency of 88.92%. This study provides basic data on mask waste carbon dioxide gasification using greenhouse gases as useful product gases.