Co-gasification Of Lignite Research Articles

Co-gasification of lignite and spent tea waste for the generation of hydrogen-rich syngas in a fluidized bed gasifier

The co-gasification of high moisture and high volatile content low-rank lignite (LG) coal and a common waste generated from the brewed tea leaves was studied in a fluidized bed gasification unit. Multiple experiments were conducted at different temperatures, ranging from 800 °C to 900 °C, at fixed operating parameters to elucidate the catalytic thermo-chemical impact on the gasifier performance parameters. The catalytic effect of alkali and alkaline earth metals (AAEMs), especially CaO, K2O, and Na2O present in the spent tea waste (STW) sample, on the product gas composition and performance parameters during the co-gasification experiments with LG was demonstrated. Mixed blends of LG and STW showed enhancement in the overall reactivity of the steam gasification runs, compared to the LG-only feed, primarily due to the change in the surface morphology, textures, and pore structures of the solid product ash samples, as identified with the electron spectroscopy analysis. Liquid and product samples were analyzed using characterization techniques such as Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) analytical techniques, along with the proximate, ultimate, and X-ray fluorescence (XRF) analysis of the gasification feed samples. An optimized blend ratio of 20 wt % of STW with LG sample enhanced the volumetric gas composition of H2 and CH4 gases from 52.03 % to 61.32 % and 3.98 %–5.45 % (on a dry-N2-free basis) with a relatively constant CO gas composition. It showed a reduced CO2 composition from 28.64 % to 18.25 % (on a dry-N2-free basis) for the gasification temperature of 900 °C. Even at the lower gasification temperatures of 800 °C and 850 °C with LG + STW feed, steam gasification experiments showed relatively comparable or superior performance to gasification experiments at 900 °C with LG-only feed. The present study indicated a holistic way to utilize the spent tea waste generated from millions of homes and commercial establishments in various parts of the world with potential application towards synergistic gasification process with other conventional carbon-source materials.

Options for net zero emissions hydrogen from Victorian lignite. Part 1: Gaseous and liquefied hydrogen

This two-part paper investigates the feasibility of producing export quantities (770 t/d) of blue hydrogen meeting international standards, by gasification of Victorian lignite plus carbon capture and storage (CCS). The study involves a detailed Aspen Plus simulation analysis of the entire production process, taking into account fugitive methane emissions during lignite mining. Part 1 focusses on the resources, energy requirements and greenhouse gas emissions associated with production of gaseous and liquefied hydrogen, while Part 2 focusses on production of ammonia as a hydrogen carrier.In this study, the proposed process comprises lignite mining, lignite drying and milling, air separation unit (ASU), dry-feed entrained flow gasification, gas cooling and cleaning, sour water-gas shift reaction, acid gas removal, pressure swing adsorption (PSA) for hydrogen purification, elemental sulphur recovery, CO2 compression for transport and injection, hydrogen liquefaction, steam and gas turbines to generate all process power, plus an optional post-combustion CO2 capture step. High grade waste heat is utilised for process heat and power generation. Three alternative process scenarios are investigated as options to reduce resource utilisation and greenhouse gas emissions: replacing the gas turbine with renewable energy from off-site wind turbines, and co-gasification of lignite with either biomass or biochar. In each case, the specific net greenhouse gas intensity is estimated and compared to the EU Taxonomy specification for sustainable hydrogen.This is the first time that a coal-to-hydrogen study has quantified the greenhouse gas emissions across the entire production chain, including upstream fugitive methane emissions. It is found that both gaseous and liquefied hydrogen can be produced from Victorian lignite, along with all necessary electricity, with specific emissions intensity (SEI) of 2.70 kg CO2-e/kg H2 and 2.73 kg CO2-e/kg H2, respectively. These values conform to the EU Taxonomy limit of 3.0 kg CO2-e/kg H2. This result is achieved using a Selexol™ plant for CO2 capture, operating at 89.5%–91.7% overall capture efficiency. Importantly, the very low fugitive methane emissions associated with Victorian lignite mining is crucial to the low SEI of the process, making this is a critical advantage over the alternative natural gas or black coal processes.This study shows that there are technical options available to further reduce the SEI to meet tightening emissions targets. An additional post-combustion MDEA CO2 capture unit can be added to increase the capture efficiency to 99.0%–99.2% and reduce the SEI to 0.3 kg CO2-e/kg H2. Emissions intensity can be further reduced by utilising renewable energy rather than co-production of electricity on site. Net zero emissions can then be achieved by co-gasification with ≤1.4 dry wt.% biomass, while a higher proportion of biomass would achieve net-negative emissions. Thus, options exist for production of blue hydrogen from Victorian lignite consistent with a ‘net zero by 2050’ target.

Cogasification performance of deashed coal with various biomass

Cogasification of lignite and EPFB is present as a production of energy sources that aim to get a synergy effect. However, not all cogasification gives better product quality than fuel parent gasification. In this study, demineralization acted as lignite pre-treatment stage is achieved through HF leaching at 70°C for 4 hours. The mixing ratio varied by lignite to empty palm fruit bunches (EPFB) are 1: 2, 1: 1, and 2: 1 both for non-demineralized lignite (BLM) and lignite demineralized (BLD). The negative synergy effect of two combination is caused by the high content of silica and alumina from the empty palm fruit bunches (EPFB). The lignite demineralization cogasification produces a lower H2 yield than BLM because it also dissolves the mineral content which functions as a catalyst for cogasification synthesis.

Chemical looping co-gasification of lignite and rice husk for syngas generation with a Co decorated Cu-based oxygen carrier

ABSTRACT In this work, the steam gasification and chemical looping gasification (CLG) of lignite and rice husk (LRH) over 5% Co3O4/CuO oxygen carrier were conducted on a fixed-bed system by non-isothermal method. The non-isothermal oxygen uncoupling experiments showed that the oxygen uncoupling temperature of 5% Co3O4/CuO (730°C) was lower than that of CuO (800°C). It was ascribed to the synergy of CuO and Co3O4. The gasification results showed that the yields of gas products (H2, CO, CO2 and CH4) in CLG of lignite or rice husk were higher than that in steam gasification because of the catalytic function of Co3O4/CuO oxygen carrier. Moreover, the catalysis of K and the transferring of active OH and H radicals from the biomass to the coal will show a synergetic effect between LRH. So the yields of gas products in chemical looping co-gasification (CLCG) were also higher than that in steam co-gasification or individual CLG. Furthermore, the carbon conversion rate in CLCG of LRH was 24.99% higher than that in steam co-gasification. It showed that CLCG of coal and biomass was effective for syngas generation, and the presence of 5% Co3O4/CuO oxygen carrier enhanced the generation of syngas.

Co-gasification of lignite and used car tires by H2O/air thermal plasma

The article considers a high-voltage AC plasma torch working on a mixture of water vapor and air up to 90 kW. A thermodynamic calculation of the co-gasification of used automobile tires and lignite is presented. Assessment of the operation of the plasma torch working on mixtures of H2O/air at co-gasification of lignite and used car tires shows prospect of these processes implementation.

Effect of fuel blend composition on hydrogen yield in co-gasification of coal and non-woody biomass

In this study, torrefaction of sunflower seed cake and hydrogen production from torrefied sunflower seed cake via steam gasification were investigated. Torrefaction experiments were performed at 250, 300 and 350 °C for different times (10–30 min). Torrefaction at 300 °C for 30 min was selected to be optimum condition, considering the mass yield and energy densification ratio. Steam gasification of lignite, raw- and torrefied biomass, and their blends at different ratios were conducted at downdraft fixed bed reactor. For comparison, gasification experiments with pyrochar obtained at 500 °C were also performed. The maximum hydrogen yield of 100 mol/kg fuel was obtained steam gasification of pyrochar. The hydrogen yields of 84 and 75 mol/kg fuel were obtained from lignite and torrefied biomass, respectively. Remarkable synergic effect exhibited in co-gasification of lignite with raw biomass or torrefied biomass at a blending ratio of 1:1. In co-gasification, the highest hydrogen yield of 110 mol/kg fuel was obtained from torrefied biomass-lignite (1:1) blend, while a hydrogen yield from pyrochar-lignite (1:1) blend was 98 mol/kg. The overall results showed that in co-gasification of lignite with biomass, the yields of hydrogen depend on the volatiles content of raw biomass/torrefied biomass, besides alkaline earth metals (AAEMs) content.

Co-gasification of lignite and waste wood in a pilot-scale (10 kWe) downdraft gasifier

Gasification of lignite and waste wood mixtures is investigated in an atmospheric pilot-scale (10 kWe) downdraft gasifier, employing air as the gasifying medium. The system was originally designed and built for lignite fuel. The gasifier was operated on various lignite particle sizes; 22–25 mm particle size was found favourable. However, clinker formation was observed during operation of gasifier using lignite as a fuel. Other issues were clinker formation, bridging or channel burning, erosion and corrosion due to high ash content of lignite, etc. The co-gasification study was intended to minimize the clinker formation along with improvement in the producer gas heating value. In order to do so, experiments with mixture of waste wood-lignite were carried out. Mixture ratios of 10%–90%, 20%–80% and 30%–70% (w/w) of waste wood-lignite were investigated and results of co-gasification experiments were compared to lignite only gasification. The lignite and wood particle size was 22–25 mm and 50 × 50 × 5 mm respectively. The gasifier performance was evaluated on various parameters namely, specific gas yield, efficiency based on energy and exergy, fuel consumption rate and gas composition. Mass and energy balances were carried out for gasification of lignite and its mixture with waste wood. With increase in wood percentage, the clinker formation reduced and almost became negligent with wood percentage reaching to 30%. The energy efficiency, exergy efficiency, LHV (Lower heating value) of gas and gas yield increased by 8.92%, 11.66%, 6.31% and 9.33%, respectively.

Techno-Environmental Assessment Of Co-Gasification Of Low-Grade Turkish Lignite With Biomass In A Trigeneration Power Plant

Abstract Trigeneration or Combined Cooling, Heat and Power (CCHP) which is based upon combined heat and power (CHP) systems coupled to an absorption chiller can be recognized as one of the best technologies recovering biomass effectively to heat, cooling and power. Co-gasification of the lignite and biomass can provide the possibility for safe and effective disposal of different waste types as well as for sustainable and environmentally-friendly production of energy. In this article, a trigeneration system based on an IC engine and gasifier reactor has been simulated and realized using Thermoflex simulation software. Performance results suggest that utilization of sustainably-grown biomass in a Tri-Generation Power Plant (TGPP) can be a possibility for providing cooling, heat and power demands with local renewable sources and reducing the environmental impacts of the energy conversion systems.

Synergy Effect in Co-Gasification of Lignite and Char of Pine Sawdust

Synergy Effect in Co-Gasification of Lignite and Char of Pine Sawdust

Cogasification of Polyethylene and Lignite in a Dual Fluidized Bed Gasifier

This work focuses on the cogasification of lignite and fresh polyethylene (PE) granulate at lignite ratios ranging from 0 to 100% in the dual fluidized bed pilot plant at Vienna University of Technology. The operating parameters for all gasification and cogasification tests were kept constant. The input fuel power was 90 kWth, while the gasification temperature was 850 °C. Olivine was used as the bed material. In addition to standard online measurements of the permanent components of the product gas, the tar content was also measured. Using lignite in the feedstock improved quality in terms of reducing tar load and increasing the possibility of adjusting the main components of the product gas. The beneficial effects of lignite could even be attained at low concentrations of lignite in the fuel mix with PE.