Coal Gasification Reaction Research Articles

Comparative experimental study of ash formation behaviors during the fixed-bed gasification of coal water slurry and dry pulverized coal prepared from Shenmu coal

The mechanism of ash formation during coal gasification is very important for the safety and stability of gasifier operation. This study comparatively investigated the ash formation behaviors during the gasification of coal water slurry and dry pulverized coal. Shenmu coal was gasified in a CO2 atmosphere at 900 °C using a fixed-bed reactor to prepare chars and ashes. Computer-controlled scanning electron microscopy was employed to characterize the compositions and particle sizes of minerals in the raw coal, coal water slurry gasification ash, and dry pulverized coal gasification ash. Morphological characteristics reveal that, during gasification, coal water slurry gasification char exhibits obvious agglomeration compared to the dry pulverized coal gasification char. The changes of mineral compositions indicate that, during both coal water slurry and dry pulverized coal gasification, minerals follow nearly identical transformation pathways, but the degrees of transformation are different. The influence of char agglomeration on heat transfer may be the reason for the less transformation of K Al-silicate and kaolinite during the coal water slurry gasification. Furthermore, in comparison to dry pulverized coal gasification, more Ca in calcite and S in pyrite transfer into gypsum during the coal water slurry gasification. The results from thermodynamic equilibrium calculations indirectly suggest that this may be attributed to the limited internal diffusion of CO2 within coal water slurry gasification char resulting from char agglomeration during gasification. Overall particle size distributions of minerals in raw coal, coal water slurry gasification ash, and dry pulverized coal gasification ash demonstrate that the degrees of mineral fragmentation are almost consistent during both coal water slurry and dry pulverized coal gasification. However, differences in the degrees of mineral transformation led to different particle size distributions of various minerals between coal water slurry gasification ash and dry pulverized coal gasification ash. This study mainly focuses on the influence of water in coal water slurry on ash formation, and it has not considered the influence of other factors, such as ash content, hydrophilicity, caking property, and gasification reactivity of coal, which need further research to explore.

Theoretical study on coal gasification behavior in CO2 atmosphere driven by slag waste heat

Blast furnace slag, a main by-product of ironmaking process, contained high-quality sensible heat, accounting for almost 30 % of total energy consumption in iron and steel industry. This paper proposed CO2 coal gasification method aimed at recovering waste heat from blast furnace slag. Based on Gibbs free energy minimization, influence of temperature, CO2/C, pressure and steam were investigated. Under optimal operating conditions at 1023–1198 K, CO2/C of 1.5–2.0 and atmospheric pressure, total amount of syngas was 2.78 kmol, with 67.1 % CO and 8.79 % H2. Addition of steam could adjust compositions of syngas. H2/CO of syngas reached 1.0, 1.5 and 2.0 when H2O(g)/CO2 were 1.45/0.55, 1.73/0.27 and 1.95/0.05, which could be used as organic raw materials for chemical industry. Meanwhile, energy and exergy efficiencies of coal gasification were found to be 63.84 % and 62.58 %, respectively, under optimal operating conditions. For different syngas products, when H2O(g)/CO2 was 1.95/0.05, exergy loss was the lowest, with internal and external exergy loss amounting to 31.80 % and 2.16 % respectively. These works provided theoretical guidance on use of the coal gasification reaction for recovering waste heat from blast furnace slag and contributed to the achievement of the strategic goal of CO2 energy saving and emission reduction.

Co-gasification of coal and biomass: synergistic effects on gasification reactivity induced by inherent organic components

ABSTRACT It is widely recognized that the synergistic effects during co-gasification process of coal and biomass are caused by the inherent alkali/alkaline earth metals (AAEM). However, the compositions of biomass and coal are complex, with main components being not only AAEM, but also aromatic, aliphatic, and heteroatom-containing compounds. Therefore, whether these organic components can also result in synergistic effects during co-gasification is necessary to be investigated. In this work, to reveal the reaction characteristics of organic components in co-gasification process, two raw materials with little content of ash were selected. The gasification behaviors of coal and biomass were studied and the influences of blending ratio and gasification temperature were mainly examined. The results showed that gasification reactivity of pure biomass was the strongest and its carbon conversion reached 100% within 33 min. With the increase of biomass ratio, gasification reactivity of mixtures was gradually enhanced, which could be ascribed to active functional groups, porous structures, and incompact macromolecular structures of biomass. At high temperature, the gasification reactivity difference was lessened among different samples. As for coal, the reactivity index at 800°C was 0.012. With the increase of biomass blending ratio from 25% to 100%, the reactivity index slowly went up to 0.023 at maximum. When temperature rose to 900°C, the reactivity index was enlarged nearly eight times compared with that of 800°C. At temperatures tested, the shrinking core mode was appropriate to describe gasification process, especially for coal and coal/biomass mixtures. Kinetic analysis showed the theoretical activation energies were all higher than the experimental values, indicating that the interaction between coal and biomass diminished activation energy. The synergy index suggested that gasification reactivity of coal was indeed enhanced during co-gasification process. However, a high-temperature environment might cover up the positive roles of biomass and the synergistic effect was hence weakened. In conclusion, the synergistic effects during co-gasification process could be induced by the organic components in coal and biomass.

Development of a laboratory unit and a solid fuel gasification reactor

The paper investigates the process of gasification of pyrolysis coal and other coal-containing materials A schematic diagram of the installation of the gasification process of pyrolysis coal and other coal-containing materials was developed, the design of the reactor for coal gasification and the methodology for conducting experiments and analysing the gasification process of pyrolysis coal and other coal-containing materials were developed. Research methods - modelling of the coal gasification process using the results of theoretical studies. A detailed analysis of the experimental and theoretical data concerning the feasibility of the pyrolysis coal gasification process was carried out, a schematic diagram of the laboratory installation and the design of the gasification reactor were developed. The main goal is to develop a method of gasification of solid pulverised fuel that will simplify the process control and ensure its stability due to the unity of the drying and gasification processes of pyrolysis coal, which are linked by means of a gasification reactor. Additionally, this method provides for the neutralisation of harmful impurities generated during the coal gasification process. As a result of theoretical studies of the solid fuel gasification process, a design of a coal gasification reactor was proposed, which is an ideal displacement reactor. The length-diameter ratio for the working part of the reactor should be at least 10:1. It is proposed to use a heat-resistant molybdenum steel tube (operating temperature up to 1600 0C) with a diameter of two inches to manufacture the reactor. Also, to study the gasification process of pyrolysis coal and other coal-containing materials, a laboratory installation for gasification of solid crushed fuel is proposed, in which a gas mixture of carbon dioxide and oxygen is fed into the reactor and serves as an activator of the gasification process. The prospects of coal processing by gasification to produce a mixture of combustible gases (H2, CO, CH4) are investigated. It is analysed that coal gasification allows obtaining valuable gas that can be used not only as an energy fuel, but also as a technological raw material for the production of methanol, dimethyl ether, hydrogen production, and use as a reducing agent in metallurgical processes.

Nuclear hydrogen production through carbonaceous-matter gasification. A physicochemical optimization

To reach the worldwide decarbonisation and the corresponding climate change mitigation, low-carbon energy sources must be used in the near-term and the role of the nuclear energy in pathways to produce net zero emissions is outstanding. This is not only because nuclear energy produces carbon-free energy, but also because it can supply high-temperature process heat to industrial applications such as the hydrogen production. Hydrogen is presently considered as the energy vector of the future to attain these environmental goals.In this paper, the possible use of a nuclear-assisted steam coal gasification process for hydrogen production is investigated in deep. As a modern High Temperature Gas Cooled Reactor (HTGR) is able to produce a gas outlet temperature of 950 °C, the nuclear heat can be transferred to a steam coal gasification plant via an intermediate helium circuit for providing the high-temperature process heat required by the endothermic gasification reactions between the steam and the carbonaceous matter.The nuclear-assisted gasification technology is considered to be attractive for the processing of an Argentine orthoasphaltite that is extracted from a minefield located in Neuquén province. The present research comprises both theoretical and experimental studies, which were addressed to get the necessary information about the optimal conditions for the hydrogen production though the steam gasification process using the Argentine orthoasphaltite as feedstock.A conceptual design of an energy complex for nuclear hydrogen, electricity and liquid fuels production is also proposed. In this conceptual design, the steam coal gasification reactor consists of two concentric vessels specially designed to separate the pyrolysis step occurring at low temperature and the char gasification step that takes place at higher temperatures. In this way, it is possible to give a full use to the volatile compounds that are present in the feedstock and are identified and characterized in this work.

Modification of extended chemical percolation devolatilization model for application to low-rank coals

For understanding coal gasification reactions, primary pyrolysis reaction is important as the first stage of the gasification reactions. Recently, the authors developed a primary pyrolysis model to predict tar formation behavior by extending the chemical percolation devolatilization (CPD) model which is often used to predict pyrolysis behavior. The extended CPD (Ex-CPD) model predicts gas and tar components as respective chemical species. Consequently, the secondary tar decomposition behavior can be calculated by elementary step-like reaction models. However, some of the coal structure parameters used in the model contradict the 13C NMR data. That is, the molecular weight of the aromatic ring clusters calculated by the original Ex-CPD decreases with the aromatic index obtained by 13C NMR. In this study, this problem was resolved by modifying the calculation procedure to determine the coal structure parameters. The recalculated aromaticity index agreed with that calculated from the 13C NMR data. The modified Ex-CPD model was validated through comparison with coal gasification experiments using a pressurized drop tube furnace. The calculation results successfully described the trend of light gases, soot, and char yield in the experiments.

The effect of CaO on coal gasification reaction with high-temperature copper slag as catalyst

ABSTRACT In order to improve the calorific value and reducibility of the syngas produced by traditional coal gasification technology, and to solve the problem of high cost of heat source in coal gasification, this paper proposes to use high-temperature copper slag as the heat carriers and catalyst for coal gasification, and CaO as the CO2 adsorbent during the coal gasification reaction. In this way, the proportion of H2 in the syngas gas can be increased, and the coal gasification reaction can be improved. In the experiment, the samples with different ratios were fully mixed, and then thermogravimetric experiment and gasification experiment were carried out. Through research, the following rules were found. The use of high-temperature copper slag as the heat source and catalyst in coal gasification can lead to a 20% increase in the final weight loss rate. Additionally, when CaO is used as the CO2 adsorbent during the coal gasification reaction, a noticeable secondary weight loss occurs at around 600°C and can reach a maximum speed of 0.19%/min. The use of the C/S/CaO = 1/1/2 ratio can result in a maximum weight loss rate of 23%. Meanwhile, the C/S/CaO = 1/2/1 group has been shown to achieve a maximum weight loss speed of 0.5%/min, and the C/S/CaO = 1/1/1 group exhibits a maximum secondary weight loss speed of 0.32%/min. The samples after gasification experiment were analyzed by SEM, CaO produced clustered iron-based and porous structure on the surface of copper slag in gasification reaction. Based on the Coats-Redfern method, kinetics of gasification reaction is obtained, and the optimum fitting function is C2, mechanism functions didn’t change with the variation of C/S/CaO. The research results suggest that CaO and copper slag can both enhance the coal gasification reaction. In addition, CaO is proven to be a more affordable and accessible CO2 adsorbent compared to other alternatives.

Study on the mechanism and reaction characteristics of metal-supported phosphogypsum as oxygen carrier in a chemical looping gasification application

This study aimed to explore the chemical looping gasification (CLG) reaction characteristics of the metal-supported composite phosphogypsum (PG) oxygen carriers (OCs) and the thermodynamic mechanism. The FactSage 7.1 thermodynamic simulation was used to explore the oxygen release and H2S removal mechanisms. The experimental results showed that the syngas yield of CLG with PG-CuFe2O4 was more than that with PG–Fe2O320/CuO40 or PG–Fe2O330/CuO30 OC at 1023 K when the water vapor content was 0.3. Furthermore, the maximum syngas yield of the CO selectivity was 70.3% and of the CO2 selectivity was 23.8%. The H2/CO value was 0.78, and the highest carbon conversion efficiency was 91.9% in PG-CuFe2O4 at the gasification temperature of 1073 K. The metal-supported PG composite oxygen carrier was proved not only as an oxygen carrier to participate in the preparation of syngas but also as a catalyst to catalyze coal gasification reactions. Furthermore, both the experimental results and FactSage 7.1 thermodynamic analysis revealed that the trapping mechanism of H2S by composite OCs was as follows: CuO first lost lattice oxygen as an oxygen carrier to generate Cu2O, which, in turn, reacted with H2S to generate Cu2S. This study provided efficient guidance and reference for OC design in CLG.

Preparation of K-N co-doped commercial cylindrical carbon via the coal partial steam gasification for CO2 adsorption

The formed activated carbon is a promosing carbon based absorbent for CO2 adsorption in fossil energy industrial process. In this paper, the preparation method of commercial formed activated carbon and the partial steam gasification of coal via the addition of K2CO3 and melamine were combined to prepare cylindrical activated carbon with high abrasive resistance and well-developed pore structure. The CO2 adsorption capacity and mechanism of the prepared carbons were also explored. The results showed that the steam gasification reactivity of coal was enhanced by the addition of K2CO3 and melamine. The prepared cylindrical carbons had the abrasive resistance higher than 95% and their specific surface area reached 1451 m2/g after K was added to coal. Nearly 70% of microporous proportion was obtained for the cylindrial carbons from the N doped and K-N co-doped coals as 1.3 times as that from undoped carbon. Both the CO2 chemisorption and physical adsorption were improved by the K/N doping. It was concluded that the N species content and narrow micropore volume (<1 nm) showed the more important role on CO2 total and physical adsorption capacity respectively. Good cyclic stability of CO2 adsorption was also observed for the doped cylindrical carbons.

Experimental study and kinetic analysis of the impact of ammonia co-firing ratio on products formation characteristics in ammonia/coal co-firing process

Ammonia is a carbon-free, hydrogen-rich fuel, which is considered as an alternative energy source with high utilization potential. Ammonia/coal co-firing in air-staged coal-fired boilers has attracted the attention of a number of academics in order to meet the aim of low carbon and NOx emissions. In this paper, ammonia/coal co-firing experiments were conducted under air-staged condition in a one-dimensional combustion-temperature controlled down-fired furnace with multi-path air inlets at 1100℃. The influence of ammonia co-firing ratio on NO and CO2 emissions, as well as CO and H2S release characteristics, was studied using Shenhua bituminous coal in air-staged and non-staged combustion conditions. Chemical reaction kinetic calculations were conducted to provide a qualitative analysis of the experimental results. Ammonia plays a complex role in the ammonia/coal co-firing process. An effective CO2 reduction was achieved with ammonia co-firing, and it was found that air-staged combustion is also effective for NO emission control in the ammonia/coal co-firing process. Considering the economy issue and NO emission control, 20–30 % ammonia co-firing ratio is recommended. However, ammonia/coal co-firing can greatly promote the coal gasification reaction, which leads to a higher concentration of CO in the reduction zone in air-staged combustion, compared with coal combustion. Meanwhile, ammonia co-firing has a significant inhibitory effect on the release of H2S from coal and will promote the subsequent decomposition process. This study explains the NO release pattern in ammonia/coal co-firing processes based on experimental results and chemical kinetics calculations, which provides a promising technical advancement direction for the coal-fired power plants to achieve a signification reduction of both CO2 and NO emissions.

Techno-economic analysis of a novel full-chain blast furnace slag utilization system

As the main solid waste in the iron and steel industry, the waste heat recovery and comprehensive utilization of blast furnace slag had great significance for energy conservation and sustainable development. This paper proposed a novel full-chain blast furnace slag utilization system to solve the problem of waste heat recovery and high value-added production. Cascade recovery of slag waste heat was realized by using coal gasification reaction and the waste heat recovery ratio reached 73.61%. Meanwhile, two kinds of high value-added products of X-type zeolite and hydrotalcite-like compounds were synthesized simultaneously by using the beneficial components of blast furnace slag after fully recovering waste heat. Ultimately, the economic feasibility of the system was analyzed from two aspects of investment and profit. Under the reasonable economic assumptions, payback period of the project was 0.14 years, 10-year net present value was $ 326493.98 million, return on investment and internal rate of return were 737.74% and 312.82%, respectively. Through sensitivity analysis, the project could still be profitable in the production year under the condition that the sensitive factors of the system fluctuated within 40%. With great economic benefit and anti-risk ability, the novel full-chain blast furnace slag utilization system had potential in energy saving and emission reduction of iron and the iron and steel industry and the prospect of large-scale application.

Effect of CaO-SiO2-FeO slag system on coal gasification reaction in CO2-Ar atmosphere and kinetic analysis

A new method of coal gasification with steelmaking slag as heat carrier and catalyst is put forward. At the same time, from the carbon cycle perspective, CO2 is used as a gasification agent instead of water vapor. The effects of coal type, slag ratio, and experimental temperature on coal gasification reaction were discussed through constant temperature thermogravimetry, heating thermogravimetry experiments, and the kinetic analysis of thermogravimetry data carried out. The results show that steelmaking slag has a catalytic effect on coal gasification reaction, which is beneficial to coal gasification reaction, but the additional amount of slag has a suitable value. Because low-rank coal contains more oxygen-containing functional groups, the catalytic effect of slag on low-rank coal is stronger. The gasification reaction temperature should be controlled near the ash melting point temperature of coal. At the same time, the kinetic parameters of coal gasification reaction under different conditions were obtained, and the kinetic mechanism model was constructed. This study is of great significance to the recovery and utilization of waste heat of steelmaking slag and the emission reduction of greenhouse gases.

Migration of Co, Cd, Cu, Pb to the groundwater in the area of underground coal gasification experiment in a shallow coal seam in the experimental mine ‘Barbara’ in Poland

A numerical model of inorganic pollutants migration in the area of ​​ underground coal gasification (UCG) reactor in the post-operational phase was constructed in this study. Also the deceleration of migration and the shape of the contaminant plume in individual geological formations of the reactor surroundings, resulting from different values ​​of sorption affinity, were compared. The simulations were carried out for four selected metals (Co, Cd, Cu, Pb), which in relation to the raw coal and post-process char showed different sorption properties. The sorption parameters of the tested systems were determined experimentally on the basis of the Freundlich isotherm equation. The retardation coefficients were calculated and the degree of sorption intensity in hydrogeological media was classified from II (in the cobalt-char and metals-coal systems) to the IV class of sorption intensity (in the copper-char system).The modeling was carried out using the finite element method (FEM) in the COMSOL Multiphysics computing environment in a two-dimensional plane. The simulation of pollutant migration was carried out for the transient state, with the assumed time horizon up to 20 years after the termination of the UCG experiment. The bottom of the cavity formed due to the coal gasification in situ (10 m × 20 m ellipse) was assumed as the source of contamination and the spread of metals in a horizontal plane 200 m long and 200 m wide was analyzed.To compare the extent to which sorption phenomena affect the spread of pollutants, an additional model was constructed, taking into account only the advection–dispersion movement of the contaminant plume. The consequence of sorption interactions for the tested systems was the delay of the contaminant plume migration depending on time since the termination of the gasification process and depending on the distance from the source of pollution. Due to high sorption affinities, the post-process char acts as an effective buffer for inorganic pollutants and slows down the migration of analyzed metals even 20 years after UCG experiment. The greatest slowdown in migration in relation to the velocity of groundwater flow as a result of sorption occurred for copper transport in the char layer.

The influence of calcium lignosulphonate addition on non-isothermal pyrolysis and gasification of demineralised bituminous coal fines

• Coal fines were demineralised using acid de-ashing treatment. • CaLS added to the coal fines and demineralised coal in different proportion showed an increase in compressive strength. • CaLS blended samples showed higher reactivity when compared to the demineralised coal and coal fines. • 5% CaLS addition did not influence coal gasification rate significantly. • An increase in CaLS blends correlates with an increase in reactivities. Amorphous calcium lignosulphonate (CaLS), a by-product of the paper industry, was evaluated as an adhesive to bind demineralised bituminous coal fines in various weight percentage ratios. Sequential acid (HCl, HF, HCl) leaching was used to reduce mineral matter content in the coal fines. The pyrolysis and gasification of the samples were investigated in laboratory-scale experiments to determine the effect of the CaLS addition on the pyrolysis and gasification reactivities. Coal-CaLS blends consisting of 5, 10, and 15% calcium lignosulphonate were prepared, compressed into pellets, and characterised using proximate, X-ray diffraction, and X-ray fluorescence analyses. An increase in binder concentration increases the mechanical strength of the pellets due to the increased interparticle contact area. The relative coal gasification reaction reactivity (1/T max and 0.5/T 50 ), which was determined from the derivative thermogravimetry curves, increases with CaLS addition. The experimental results revealed that these wastes (coal fines and calcium lignosulphonate) could be utilised in thermochemical processes. Utilising these wastes will reduce the environmentally unfriendly volumes of amorphous calcium lignosulphonate and coal fines particles.

Transport of heat, moisture, and gaseous chemicals in hydro-mechanically altered strata surrounding the underground coal gasification reactor

Underground coal gasification (UCG) has a great potential to be accompanied by the technology of (enhanced) coal bed methane ((E)CBM) and carbon capture and storage (CCS), enhancing coal energy efficiency and mitigating climate change. This study aims to assess the environmental impact of three field-scale UCG hypothetical sites targeting deep-buried seams during the UCG operational stage in the combined CBM-UCG application. For this purpose, a risk assessment methodology is developed with consideration of the geomechanical and hydrogeological impact of UCG operations on the overlying strata by analogy to longwall mining operations. A series of numerical simulations are conducted to investigate the effect of variations in the saturation conditions around the UCG reactor, the change of rock permeability, and the UCG reactor operation duration on the propagation of heat, moisture and gaseous chemicals. The results demonstrate that CBM-UCG activities in the three sites are not likely to cause negative impacts on the environment during the UCG process when the behaviour of the reactor and the change of the surrounding strata are in control as expected. This work can provide insights in terms of environmental decision making, regulation and management to prevent reduction in gasification efficiency, to conduct the post-UCG (E)CBM process and to mitigate the UCG gas leakage and contamination of surrounding aquifers, highlighting where additional information is required in CBM-UCG activities.

The effect of rock permeability value on groundwater influx in underground coal gasification reactor

Rock permeability value is one of the most significant rock’s physical properties that affect groundwater influx processes in underground coal gasification (UCG). This value of rock permeability (K), namely the vertical permeability of flanking rocks (Kv) and horizontal permeability of coal (Kh). The purpose of this study was to determine the extent of the influence of the value of rock permeability on the potential of groundwater influx. The effect of rock permeability on groundwater influx into the UCG gasification reactor cavity in the presence of thermal loads and mineral composition content is large and significant to consider. Based on the resistance to heat loads, the type of sandstone lithology is relatively more resistant compared to siltstone and claystone lithology.

Changes in active sites and reactivity induced by interactions among Ca, Si and Al during coal char gasification

Chemical structure of char plays an essential role in coal gasification reactivity, especially functional groups and active site. In this study, reactivity difference was discussed by integrating functional groups, mineral interactions with active site. A thermogravimetric analyzer was applied to determine the active site by adsorption and desorption process. X-ray photoelectron spectroscopy (XPS) results prove that coal char loaded Ca (Ca + Dem-char) and the char containing Ca, Si and Al (Ca+(Si, Al)-char) have fewer ratio of ether (COC)and carbonyl (CO) groups because Ca species facilitate the decomposition of these groups in pyrolysis. Active site analysis illustrates that compared with demineralized char (Dem-char), char with Si and Al ((Si, Al)-char) has the smallest amount of active site, which is the direct factor for an inferior gasification reactivity, because Si and Al not only have no function to adsorb gasifying agent but also block some active site and even make some carbon become inert.

Study on pulverized coal gasification using waste heat from high temperature blast furnace slag particles

A combined species transport and reaction-discrete phase model was established to numerically study pulverized coal gasification using waste heat from high temperature slag particles. The effects of slag particles temperature, coal/gasification agent mass ratio and water content in gasification agent on the gasification characteristics were discussed. The results indicate that higher particle temperature leads to better gasification reaction efficiency. Compared to the maximum syngas productivity (67.9%) and carbon conversion efficiency (91.7%) at 1500 K, they are respectively reduced to about 45% and 60% when temperature drops to 1000 K. Excessive or insufficient pulverized coal would have a negative effect on the syngas production for a specific flow rate of gasification agent, and the appropriate proportion range is 0.8–0.84. The CO yield declines with the increase of particles diameter, while H2 firstly increases and then declines attributing to the lower gasification agent temperature and higher flow velocity gained at larger diameter. The raise of water content in gasification agent is beneficial to H2 production, but CO yield continues to decline after the water content exceeds 5% for the reason that the incomplete combustion of volatiles and the gasification reaction of coke are inhibited. The diameter of slag particles and the water content suitable for coal gasification reaction are 2.0–2.5 mm and 5%–10%, respectively.

Development of new technology for coal gasification purification and research on the formation mechanism of pollutants

Coal-fired power generation is the main source of CO2 emission in China. To solve the problems of declined efficiency and increased costs caused by CO2 capture in coal-fired power systems, an integrated gasification fuel cell (IGFC) power generation technology was developed. The interaction mechanisms among coal gasification and purification, fuel cell and other components were further studied for IGFCs. Towards the direction of coal gasification and purification, we studied gasification reaction characteristics of ultrafine coal particles, ash melting characteristics and their effects on coal gasification reactions, the formation mechanism of pollutants. We further develop an elevated temperature/pressure swing adsorption rig for simultaneous H2S and CO2 removals. The results show the validity of the Miura-Maki model to describe the gasification of Shenhua bituminous coal with a good fit between the predicted DTG curves and experimental data. The designed 8–6–1 cycle procedure can effectively remove CO2 and H2S simultaneously with removal rate over 99.9%. In addition, transition metal oxides used as mercury removal adsorbents in coal gasified syngas were shown with great potential. The techniques presented in this paper can improve the gasification efficiency and reduce the formation of pollutants in IGFCs.

Interaction and kinetic analysis of co-gasification of bituminous coal with walnut shell under CO2 atmosphere: Effect of inorganics and carbon structures

In this study, co-gasification behaviors and synergistic interaction of bituminous coal and walnut shell under CO2 atmosphere were investigated by using a thermogravimetric analyzer. The evolution of physicochemical properties of samples was characterized with an inductively coupled plasma emission spectrometer, an X-ray fluorescence spectrometer, and an X-ray diffractometer. The results indicated that the addition of walnut shell significantly enhanced the gasification reactivity of coal, and coal/biomass blend ratio of 7:3 showed an intense gasification. Moreover, a significant co-gasification interaction was observed in the char gasification stage and demonstrated that a high coal/biomass blend ratio induced the formation of amorphous carbons and further accelerated the co-gasification reaction. Meanwhile, the active inorganics were severely released as 30 wt% bituminous coal added to walnut shell, causing a deteriorative gasification reactivity. Furthermore, three kinetic models illustrated that the coal/biomass blend ratio of 7:3 required a minimum activation energy to initialize gasification. The findings in this work would be beneficial for revealing the co-gasification mechanism of biomass and coal, and provide a useful basis on their multi-scale applications.