Solubility of Tar Model Compounds in Various Solvents for Tar Removal in a Dual Fluidized Bed Biomass Gasification Process

Production of high quality product gas via biomass steam gasification is a promising technology. However, impurities in the product gas, namely tars, cause problems in the downstream gas processing operations and thus they need to be removed efficiently. Oil scrubbing is an effective solution for tar removal due to its non-polar characteristic which is similar to tar nature. In this research, solubility values of five simulated tar compounds were experimentally investigated for selecting the new scrubbing solvent. The simulated tar compounds investigated represent those found in the dual fluidized bed steam gasification of wood biomass, which are: naphthalene, biphenyl, anthracene, fluoranthene, and pyrene. The scrubbing solvents tested in this research are classified into biodiesels, vegetable oils, and diesel. Biodiesel used are rapeseed methyl ester (RME) and 2 different palm methyl esters (denoted as PME1 and PME2). Vegetable oils are sunflower oil, refined palm oil, Thai rice bran oil, and crude palm oil. All of the solubility tests were performed in the laboratory-scale test-rig at 30, 50, 70, and 80°C. Biodiesels are found to be the effective solvent in dissolving the tar compounds. PME1 shows the similar tar removal performance to RME but is more readily available; therefore, PME1 is chosen to be used as a scrubbing solvent at the Thailand 1 MWel prototype DFB gasifier at Nong Bua district in Nakhon Sawan province, Thailand

Influence of Solvent Temperature and Type on Naphthalene Solubility for Tar Removal in a Dual Fluidized Bed Biomass Gasification Process

Tar condensation is a cause of blockage in downstream application of the gasification process. An oil scrubber is considered as an effective method for tar removal. In this research, the naphthalene solubility in different local Thai oils and water was investigated in a laboratory-scale test-rig. The solubility value was conducted at 30, 50, 70, and 80°C. Biodiesels investigated were rapeseed methyl ester (RME) and two different palm methyl esters (PME 1 and PME 2). Furthermore, vegetable oils including sunflower oil, rice bran oil, crude palm oil, and refined palm oil were examined. The results showed that higher temperature enhanced naphthalene solubility in all types of investigated oils. Biodiesel has the highest value of naphthalene solubility. All scrubbing oils have similar naphthalene solubility trends at the temperature range of 50-80°C in the order of RME > PME 1 > PME 2 > diesel > sunflower oil > refined palm oil > rice bran oil > crude palm oil. Based on these experimental investigations, PME 1 has a naphthalene solubility value similar to RME. Therefore, PME 1 has been selected to be tested as scrubbing solvent in the 1 MWel prototype dual fluidized gasifier located in Nong Bua district, Nakhon Sawan province, Thailand

Replacement of Palm Methyl Ester to Rapeseed Methyl Ester for Tar Removal in the Nong Bua Dual Fluidized Bed Gasification Power Plant

The blockage problem of tar in a biomass power plant is a main problem and it must be removed. Rapeseed methyl ester (RME) was imported and used as scrubbing solvent to scrub tar at a 1 MWel Nong Bua prototype Dual Fluidised Bed (DFB) gasifier in Nong Bua district, Nakhonsawan province, Thailand. Using local oil in Thailand is an attractive choice from economic viewpoint. Pervious lab test study on naphthalene solubility in different local oils in Thailand was investigated. Local palm methyl ester (PME) shows the competitive performance to the RME. In this research, PME was tested to scrub tar in an oil scrubber at the Nong Bua DFB gasifier plant. Gravimetric tar content after passed a PME scrubber was measured and compared to that from a RME oil scrubber. The results show that both solvents have similar tar removal performance due to their contents of ester, methanol, and glycerin are similar. In addition, viscosity of both solvents has no significant effect on tar removal. From the current research, therefore, PME has been used as solvent in an oil scrubber at 1 MWel Nong Bua prototype DFB gasifier with technical and economic reasons

Characterization of deposited Ti-doped lithium aluminium hydride thin film using dip coating method

Lithium aluminium hydride (LiAlH4) is an outstanding complex metal hydride as a hydrogen storage material. The hydrogen storage capacity of LiAlH4 is about 5-7 wt%. In this study, LiAlH4 concentration of 20 g/l doped with various titanium (Ti) concentration by dip coating method was examined. The titanium dioxide (TiO2) powder at 10 mol %, 25 mol % and 40 mol % was used as the Ti source. Instruments used to analyze Ti-doped LiAlH4 were X-ray powder diffraction (XRD) and scanning electron microscope (SEM). XRD was used for phase and crystallite size analysis and SEM was used for surface morphology investigation. The experimental results reveal that at the LiAlH4 concentration of 20 g/l with 40 mol% of TiO2, the smallest crystallite size with rather dense surface was shown. The small crystallite size can improve the desorption of hydrogen from its surface area. Therefore, the addition of titanium might be advantageous in improving the hydrogen storage efficiency of LiAlH4

Co-gasification of Cassava Rhizome and Woody Biomass in the 1 MWel_{el} Prototype Dual Fluidised Bed Gasifier by Gussing Renewable Energy

In the current research, the effect of the mixture ratio by weight of wood chips to cassava rhizome (100%:0%, 75%:25%, and 50%:50%) was investigated on the properties of the product gas produced from the Dual Fluidised Bed gasifier power plant. The DFB gasifier power plant is located in Nongbua district, Nakhon Sawan province, Thailand. The results from this study show that the use of 100% wood chips as a fuel generates high quality product gas as designed. The mixture of wood chips and cassava rhizome in the weight ratio of 75%:25% and 50%:50% also gives satisfactory results: steady operation conditions of the whole power plant process, good quality and quantity of product gas, however, the tar content in the product gas was slightly higher than that of using wood chips alone. The researchers found that cassava rhizome can be used as a fuel mixture together with wood chips in the current DFB gasifier at site to generate heat and electricity. The outcome of this research will create the use of waste cassava rhizome, enormously available around the power plant, as well as the broad application of gasification technology using various biomass feedstock types available in Thailand

Effect of the presence of HCl on simultaneous CO₂ capture andcontaminants removal from simulated biomass gasification producer gas by CaO-Fe₂O₃ sorbent in calcium looping cycles

This study investigated the effect of HCl in biomass gasification producer gas on the CO2 capture efficiency and contaminants removal efficiency by CaO-Fe2O3 based sorbent material in the calcium looping process. Experiments were conducted in a fixed bed reactor to capture CO2 from the producer gas with the combined contaminants of HCl at 200 ppmv, H2S at 230 ppmv, and NH3 at 2300 ppmv. The results show that with presence of HCl in the feeding gas, sorbent reactivity for CO2 capture and contaminants removal was enhanced. The maximum CO2 capture was achieved at carbonation temperatures of 680 °C, with efficiencies of 93%, 92%, and 87%, respectively, for three carbonation-calcination cycles. At this carbonation temperature, the average contaminant removal efficiencies were 92.7% for HCl, 99% for NH3, and 94.7% for H2S. The outlet contaminant concentrations during the calcination process were also examined which is useful for CO2 reuse. The pore structure change of the used sorbent material suggests that the HCl in the feeding gas contributes to high CO2 capture efficiency and contaminants removal simultaneously

Co-Gasification of Refuse Derived Fuel and Wood Chips in the Nong Bua Dual Fluidised Bed Gasification Power Plant in Thailand

Co-gasification of refuse derived fuel (RDF) and wood chips was experimented in the Nong Bua dual fluidised bed steam gasifier in Thailand. The effect of the mass of RDF pellets in the feed fuel (R/F ratio) was investigated on the performance of the entire process conditions and the product gas properties. The test results showed that the addition of small mass ratio of RDF pellets up to 30% did not affect the process operation conditions. The concentrations of H2, CO, CO2, and CH4 from a binary mixture of RDF pellets and wood chips were in the same ranges as that from pure wood chips. The lower heating value of the product gas was as high as 13.2–13.6 MJ/Nm3 for all the R/F ratio fuels. It is concluded that binary mixtures of RDF pellets and wood chips with the mass percent of R/F ratio of 10–30% are good feedstocks in the Nong Bua dual fluidised bed gasification process. The tar content, however, from the binary mixtures of RDF pellets and wood chips was higher than that of pure wood chips. The tar must be completely removed before the product gas of the RDF pellets can be utilised in the gas engine

Co-gasification of blended lignite and wood pellets in a dual fluidized bed steam gasifier: the influence of lignite to fuel ratio on NH(3) and H(2)S concentrations in the producer gas

Abstract not availableJ. Hongrapipat, W.L. Saw, S. Pan

Removal of NH(3) and H(2)S from producer gas in a dual fluidised bed steam gasifier by optimisation of operation conditions and application of bed materials

In the present study, in situ removal of ammonia (NH₃) and hydrogen sulphide (H₂S) in the producer gas has been investigated for steam gasification of woody biomass in a 100 kW dual fluidised bed (DFB) gasifier. The removal measures consist of optimisation of operation conditions and application of catalytic bed materials. The operation conditions investigated were gasification temperature in a range of 750 to 850 °C, steam to fuel ratio from 0.6 to 1.4 kg/kgdry, and mean gas residence time from 0.19 to 0.25 s. The catalytic bed materials tested included silica, ilmenite and calcined olivine sands which were applied in the DFB steam gasifier. The concentrations of NH₃ and H₂S in the producer gas were measured and the conversions of fuel nitrogen (N) and sulphur (S) to form NH₃ and H₃S were calculated based on the experimental results. The results showed that NH₃ and H₂S concentrations and conversions increased with the gasification temperature and the steam to fuel ratio. However, with increase in the mean gas residence time, the NH₃ concentration and conversion increased whereas the H₂S concentration and conversion slightly decreased. In addition, ilmenite sand and calcined olivine sand as the bed materials showed stronger influence on reduction of NH₃ and H₂S concentrations as well as fuel-N and fuel-S conversions in comparison with silica sand.Janjira Hongrapipat, Shusheng Pang, Woei Lean Sa