Kae-Long Lin

Bioenergy and products from thermal pyrolysis of rice straw using plasma torch

The aim of this work was to study the feasibility and operation performance of plasma torch pyrolysis of biomass wastes, taking rice straw as the target material. This novel method has several advantages including high heating rate, short heating time, no viscous tar and low residual char (7.45-13.78 wt.%) or lava. The productions of CO and H(2) are the major components (91.85-94.14 vol.%) in the gas products with relatively high reaction rates. The maximum concentrations of gaseous products occurring times are all below 1 min. Almost 90% of gaseous products were appeared in 4 min reaction time. The yield of H(2) increases with the increase of input power or temperature. With the increase of moisture (5-55 wt.%), the mass yields of H(2) and CO(2) also increase from the H(2)O decomposition. However, due to the CO(2) production, the accumulated volume fraction of syngas decreases with the increase of moisture.

The utilization of thin film transistor liquid crystal display waste glass as a pozzolanic material.

This investigation elucidates the pozzolanic behavior of waste glass blended cement (WGBC) paste used in thin film transistor liquid crystal displays (TFT-LCD). X-ray diffraction (XRD) results demonstrate that the TFT-LCD waste glass was entirely non-crystalline. The leaching concentrations of the clay and TFT-LCD waste glass all met the current regulatory thresholds of the Taiwan EPA. The pozzolanic strength activity indices of TFT-LCD waste glass at 28 days and 56 days were 89% and 92%, respectively. Accordingly, this material can be regarded as a good pozzolanic material. The amount of TFT-LCD waste glass that is mixed into WGBC pastes affects the strength of the pastes. The strength of the paste clearly declined as the amount of TFT-LCD waste glass increased. XRD patterns indicated that the major difference was the presence of hydrates of calcium silicate (CSH, 2 theta=32.1 degrees), aluminate and aluminosilicate, which was present in WGBC pastes. Portland cement may have increased the alkalinity of the solution and induced the decomposition of the glass phase network. WGBC pastes that contained 40% TFT-LCD waste glass have markedly lower gel/space ratios and exhibit less degree of hydration than ordinary Portland cement (OPC) pastes. The most satisfactory characteristics of the strength were observed when the mixing ratio of the TFT-LCD waste glass was 10%.

Melting of municipal solid waste incinerator fly ash by waste-derived thermite reaction

This work describes a novel approach for melting municipal solid waste incinerator (MSWI) fly ash, based on self-propagating reactions, by using energy-efficient simulated waste-derived thermite. The self-propagating characteristics, the properties of the recycled alloy and slag and the partitioning of heavy metals during the process are also studied. Experimental results demonstrate that the mix ratio of fly ash to the starting mixture of less than 30% supports the development of the self-propagating reaction with a melting temperature of 1350-2200 degrees C. Furthermore, metallic iron (or alloy) and the slag were retrieved after activation of the thermite reactions among the starting mixtures. It was noted that more than 91wt.% of iron was retrieved as alloy and the rest of non-reductive oxides as slag. During the thermite reactions, the partition of heavy metals to the SFA and flue gas varied with the characteristics of the target metals: Cd was mainly partitioned to flue gas (75-82%), and partition slightly increased with the increasing fly ash ratio; Pb and Zn, were mainly partitioned to the SFA, and the partition increased with increasing fly ash ratio; Cu was partitioned to the SFA (18-31%) and was not found in the flue gas; and moreover stable Cr and Ni were not identified in both the SFA and flue gas. On the other hand, the determined TCLP leaching concentrations were all well within the current regulatory thresholds, despite the various FA ratios. This suggests that the vitrified fly ash samples were environmental safe in heavy metal leaching. The results of this study suggested that melting of municipal solid waste incinerator fly ash by waste-derived thermite reactions was a feasible approach not only energy-beneficial but also environmental-safe.

Influence of phosphate of the waste sludge on the hydration characteristics of eco-cement

This study investigated the effects of phosphate on the hydration characteristics of three eco-cement clinkers made utilizing water purification sludge ash, sewage sludge ash and industry sludge ash. Analytical results demonstrate that the eco-cement A (ECO-A) pastes had a similar setting times, final setting times, compressive strengths and degree of hydration as ordinary Portland cement (OPC) pastes. Analytical results also show no damage to the hydration existed during the clinkerization process when adding up to 20% sludge. Increasing the P(2)O(5) content in the investigated clinker resulted in the formation of alpha-C(2)S. Compressive strength, degree of hydration and delay in setting time observed in the ECO-B and ECO-C pastes may be attributed to large amounts of alpha-C(2)S. When the amount of phosphate in ECO-C exceeded 0.46%, the amount of C(3)S in the clinker decreased, setting time increased and the strength of the eco-cement decreased.

The hydration characteristics when C2S is present in MSWI fly ash slag

Abstract This paper reports on an investigation of the hydration characteristics when C2S is present in municipal solid waste incinerator (MSWI) slag. The results can be summarized as follows: thermogravimetric analysis (TGA) observations show lower amounts of CSH and Ca(OH)2 in samples where C2S is incorporated into MSWI slag, possibly due to the partial replacement (20–40%) of the mineral constituents by less active slag. In general, the incorporation of C2S into slag, decreases the initial hydration reaction, whereas it increases the pozzolanic reactions at a later stage, by consuming Ca(OH)2. The X-ray diffraction results are in good agreement with the TGA results. Moreover, the hydration degree of the C2S–slag pastes, as determined by nuclear magnetic resonance techniques, also indicates that the C2S–slag pastes show lower hydration degree values, at all ages (1–90 days) of hydration. This may be due to the inactive behavior of an acidic film on the grains of slag, which in term retards the hydration that occurs as the Ca(OH)2 breaks down the silica framework.

Recycling waste brick from construction and demolition of buildings as pozzolanic materials

This investigation elucidates the pozzolic characteristics of pastes that contain waste brick from building construction and demolition wastes. The TCLP leaching concentrations of waste brick for the target cations or heavy metals were all lower than the current regulatory thresholds of the Taiwan EPA. Waste brick had a pozzolanic strength activity index of 107% after 28 days. It can be regarded as a strong pozzolanic material. The compressive strengths of waste brick blended cement (WBBC) that contain 10% waste brick increased from 71.2 MPa at 28 days to 75.1 MPa at 60 days, an increase of approximately 5% over that period. At 28 days, the pozzolanic reaction began, reducing the amount of Ca(OH)2 and increasing the densification. The intensity of the peak at 3640 cm— 1 associated with Ca(OH)2 is approximately the same for ordinary Portland cement (OPC) pastes. The hydration products of all the samples yield characteristics peaks at 978 cm—1 associated with C—S—H, and at ~3011 cm—1 and 1640 cm—1 associated with water. The samples yield peaks at 1112 cm—1, revealing the formation of ettringite. In WBBC pastes, the ratio Q2/Q1 increases with curing time. These results demonstrate that increasing the curing time increases the number of linear polysilicate anions in C—S—H. Experimental results reveal that waste brick has potential as a pozzolanic material in the partial replacement of cement.

Steam plasmatron gasification of distillers grains residue from ethanol production.

In this study, a plasmatron reactor was used for gasifying the waste of distillers grains at different temperatures (773, 873, 973 K) and water flow rates (1, 2, 3 mL min(-1)), which were heated to produce steam. Among all the gas products, syngas was the major component (88.5 wt.% or 94.66 vol.%) with temperatures yielding maximum concentrations at 873 K with a relatively high reaction rate. The maximum concentrations regarding gaseous production occurring times are all below 1 min. With the increase of steam, the recovery mass yield of syngas also increases from 34.14 to 45.47 approximately 54.66 wt.% at 873 K. Water-gas reactions and steam-methane reforming reactions advance the production of syngas with the increase of steam. Furthermore, the water-shift reaction also increases in the context of steam gasification which leads to the decrease of CO(2) at the same time.

Elucidating the hydration properties of paste containing thin film transistor liquid crystal display waste glass.

This study discusses the thin film transistor liquid crystal display (TFT-LCD) waste glass-blended cement (WGBC) pastes. It presents their compressive strength, their products of hydration and solid silicates changes. The samples were subjected to Fourier transformation infrared spectroscopy, differential thermal and thermo-gravimetric analysis and (29)Si magnetic angle spinning/nuclear magnetic resonance. The experimental XRD results demonstrated the speciation of the TFT-LCD waste glass, and that the major component was SiO(2). At 40% substitution of TFT-LCD waste glass, at 28 days and 56 days, the compressive strength was 35% and 30% lower, respectively, than that of the Portland cement paste. The intensity of the Ca(OH)(2) band at 3,710 cm(-1) in the 56-day hydrated products of the WGBC pastes that contain TFT-LCD waste glass exhibit comparatively weak peaks suggesting that much Ca(OH)(2) during hydration was consumed. Later, the CSH contents of the WGBC pastes increased, revealing that liberated Ca(OH)(2) was consumed in pozzolanic reactions.

A Comparison between Sludge Ash and Fly Ash on the Improvement in Soft Soil

Abstract In this study, the strength of soft cohesive subgrade soil was improved by applying sewage sludge ash as a soil stabilizer. Test results obtained were compared with earlier tests conducted on soil samples treated with fly ash. Five different proportions of sludge ash and fly ash were mixed with soft cohesive soil, and tests such as pH value, compaction, California bearing ratio, unconfined compressive strength (UCS), and triaxial compression were performed to understand soil strength improvement because of the addition of both ashes. Results indicate that pH values increase with extending curing age for soil with sludge ash added. The UCS of sludge ash/soil were 1.4–2 times better than untreated soil. However, compressive strength of sludge ash/soil was 20–30 kPa less than fly ash/soil. The bearing capacities for both fly ash/soil and sludge ash/soil were five to six times and four times, respectively, higher than the original capacity. Moreover, the cohesive parameter of shear strength rose with increased amounts of either ash added. Friction angle, however, decreased with increased amounts of either ash. Consequently, results show that sewage sludge ash can potentially replace fly ash in the improvement of the soft cohesive soil.

Co-pyrolysis of sunflower-oil cake with potassium carbonate and zinc oxide using plasma torch to produce bio-fuels

This study examined the effects of additives of potassium carbonate (K2CO3) and zinc oxide (ZnO) on the pyrolysis of waste sunflower-oil cake using a 60 kW pilot-scale plasma torch reactor. The major gaseous products were CO and H2. The productions of CO and CH4 increased while that of H2 decreased with the addition of K2CO3. The use of ZnO reduced while enhanced the formation of CO and H2, respectively. In order to match the appeal of resource reutilization, one can use the waste K2CO3 resulted from the sorption of CO2 with KOH in greenhouse gas control and the waste ZnO obtained from the melting process as additives for the co-pyrolysis of sunflower-oil cake, yielding fuels rich in CO and H2, respectively.