Coal-water Mixture Research Articles

Research Results and Applications of Torch Discharge in the Goubau Line

The waveguide-coaxial microwave setup for an excitation of erosion torch discharge at the end of a single-conductor Goubau line in open air has been developed. Properties of erosion torch discharge and surface wave propagation in the Goubau line have been investigated. Two modes of the setup operation when the line acts as a spike antenna and also as surface waveguide supporting microwave energy transmission to plasmoid were considered. Aspects of setup application for refractory metal thin-film spattering, utilization of natural gases, and coal-water mixture firing were discussed.

Pressurized oxy-coal mild combustion for clean-coal technology

In this paper we consider an oxy-coal thermoelectric plant fed by a coal-water mixture ( slurry ) and oxygen (instead of air). The use of pure oxygen makes it easier to capture CO 2 . A distinctive feature of such a plant is that the combustion and flue gases system operates at high pressure (about 10 bar). We develope a model based on first principles equations in order to study the startup procedures.

Pre-combustion, post-combustion and oxy-combustion in thermal power plant for CO 2 capture

This paper presents a summary of technical-economic studies. It allows evaluating, in the French context, the production cost of electricity derived from coal and gas power plants with the capture of CO 2, and the cost per tonne of CO 2 avoided. Three systems were studied: an Integrated Gasification Combined Cycle (IGCC), a conventional combustion of Pulverized Coal (PC) and a Natural Gas Combined Cycle (NGCC). Three main methods were envisaged for the capture of CO 2: pre-combustion, post-combustion and oxy-combustion. For the IGCC, two gasification types have been studied: a current technology based on gasification of dry coal at 27 bars (Shell or GE/Texaco radiant type) integrated into a classical combined cycle providing 320 MWe, and a future technology (planned for about 2015–2020) based on gasification of a coal–water mixture (slurry) that can be compressed to 64 bars (GE/Texaco slurry type) integrated into an advanced combined cycle (type H with steam cooling of the combustion turbine blades) producing a gross power output of 1200 MWe.

Effect of dispersing and stabilizing additives on rheological characteristics of the upgraded brown coal water mixture

Upgraded brown coal water mixture (UBCWM) preparation by using an Indonesian upgraded coal produced by upgraded brown coal (UBC) process, was carried out to study the effect of dispersing and stabilizing additives on rheological behavior of the UBCWM. Three kinds of anionic dispersing additives, naphthalene sulfonic formaldehyde condensate (NSF), poly (meth) acrylate (PMA) and poly styrene sulfonic acid (PSS) and three kinds of stabilizing additives, carboxyl methyl cellulose (CMC), rhansam gum (S-194) and gellan gum (S-60) were used in this study. Results indicate that the addition of NSF 0.3 wt.% together with S-194 0.01 wt.% is effective in preparing UBCWM with good slurryability and stability, based on its rheological characteristics with the apparent viscosity at shear rate of 100 s − 1 and yield stress at zero point of shear rate. The rheological behavior of all of the UBCWM that prepared, exhibits non-Newtonian Bingham plastic. From the economical point of view, the price of S-194 is expensive. On the other hand, CMC is cheap and abundant. Therefore, the addition of CMC 0.01 wt.% together with NSF 0.3 wt.% is also effective in preparing UBCWM with good fluidity and stability.

Experimental study of residence time distributions of ball-mill circuits grinding coal-water mixtures

Residence time distributions (RTDs) were estimated by water tracing in a number of wet overflow ball mills (diameters 0.38 to 4.65 m) producing dense, coal-water slurries. In open-circuit mills of 0.38 m diameter and various length-diameter (LID) ratios, the mean residence times of solid were also determined from measured mill holdups. Holdup increased with increased mill feed rate, but the mean residence times of coal and water were still equal to each other. The experimental residence time distributions were fitted to the Mori-Jimbo-Yamazaki semi-infinite, axial mixing model, and the dimensionless mixing coefficient was determined for each of 25 tests in single- and two-compartment mills. This coefficient was found to be independent to the feed rate but linearly proportional to the D/L ratio. The mixing coefficient was smaller for two-compartment mills than for single-compartment mills, showing that there was reduced mixing introduced by the diaphragm separating the compartments. Equations are given to scale residence time distributions for changes in mill diameter and length.

Effects of chemicals and blending petroleum coke on the properties of low-rank Indonesian coal water mixtures

In this study, the effects of different chemical additives including dispersant and stabilizer on the solid loading, viscosity, rheological behaviour and static stability of coal water mixtures have been investigated. In the experiments, naphthalene sulfonate formaldehyde condensate (NSF) was selected as dispersant and carboxymethyl cellulose sodium salt (CMC-Na) and nano-stabilizer were employed as stabilizers. An Indonesian low-rank coal, taken from Berau, East Kalimantan, was used for the study. To obtain high-loaded slurry, Liaohe petroleum coke was used to blend with Indonesian coal sample. The results of the experiments showed that adding chemical additives and blending Liaohe petroleum coke can effectively improve the slurryability of Indonesian low-rank coal.

Properties of Some Kinds of Slurry Fuels and Their Combustion Behavior

Some kinds of slurry fuels, which are comprising about 70% coal, oil pitch, vacuum residue (asphalt) or biomass such as wood chips, and about 30% water containing small amount of chemicals. were investigated in terms of fuel properties and combustion characteristics. Those slurry fuels have wide particle size distribution of sub-micron to 500μm, heating values of 20000 to 28000 kJ/kg, viscosities of 200 to 800 mPa·s@20°C and sulfur of 0.1 to 4wt%, depending on properties of raw feedstocks. From combustion tests using the pilot scale combustion furnace, steady flame and good combustion were observed for coal water mixture (CWM) and asphalt-residue water mixture (As-RWM), on the other hand, a few sparkles and long period combustion of char were observed for pitch-residue water mixture (Pi-RWM). Such different combustion characteristics, depending on slurry oils, were elucidated in terms of microexplosion, combustion characteristic times, and thermal decomposition by the combustion of a single droplet in the electrically heated furnace and the thermo-gravimetric analysis (TG/DTA). In order to obtain fundamental data in prediction of practical furnace combustion for biomass slurry fuel (BSF), the combustion behavior of BSF droplets was obsrved in the electric furnace and its combustion characteristics time was discussed in comparison with those of CWM, As-RWM, and Pi-RWM.

Numerical simulation and innovation on magnesium reduction process

The thermal process of L.M.Pidgeon’s reduction art, widely used in magnesium production, is numerically simulated. It is shown that the thermal efficiency will be highly enhanced with the increase of heat-exchange area or the intensification of heat exchange between flame and the outer surface of the reduction jars. An innovation has been made by fuel-shifting (from coal to Coal-Water Mixture), up-draft reduction furnace configuration, multi-layer jars installation and waste heat recovery. A bench scale furnace has been constructed and put into operation to identify the simulation and new design.

An investigation on effects of various parameters on viscosities of coal–water mixture prepared with Erzurum–Aşkale lignite coal

In this study the effects of parameters such as coal loading (wt.%), the initial pH of mixture, the addition of various electrolytes, surfactants and temperature on the viscosity and rheologic parameters of coal–water mixture (CWM) have been investigated. The apparent viscosity was measured with a RV8-Brookfield rotating type viscosimeter. The additives used were AlCl 3 and K 2HPO 4 as the electrolytes and Cetyltrimethyl Ammonium Bromide (CTAB), Sodium Dodecyl Sulphate (SDS) and Borrosperse NA-3A as the surfactants. It was found that the most effective additives, in terms of the viscosity reduction, were CTAB and K 2HPO 4, and that the CWM which had coal concentrations up to 50% (based on the weight of dry coal) could be prepared by using each additives. In addition, the viscosities of CWM with increasing temperature were found to increase at low speed, and decrease at high speed.

Effect of compound inorganic nano-stabilizer on the stability of high concentration coal water mixtures

In this paper, two kinds of inorganic nanoparticles based on different manufacturing processes were used as stabilizers of coal water mixtures (CWMs). The size and shape of nano-stabilizers and their steady mechanisms were explained by study of TEM and zeta potential. The properties, zeta potential, rheology and the stationary stability of coal water mixtures made up nano-stabilizers and different coal samples were investigated. In order to achieve static repulsion and steric hindrance effects simultaneously, based on the weight proportion, two nano-stabilizers were compounded. Experiments have proved that the compound inorganic nano-stabilizer has an advantage over conventional stabilizer, such as carboxymethyl cellulose sodium salt (CMC–Na), and it can be developed as a new type of stabilizer.

Preparation of Carbonized Biomass Water Mixture and Upgraded Coal Water Mixture

Biomass is the third largest primary energy resource in the world after coal and oil. Due to its huge potential, the renewable and the corresponding positive role for CO2 reduction, the use of carbonized biomass for energy purpose is expected to increase. The carbonized biomass comes from agricultural waste and forest by-product. Carbonized plant and carbonized coconut cell biomass were mixed with water to study the possibilities of slurry preparation as a carbonized biomass water mixture (CBWM). Beside that, the upgraded coal by an upgraded brown coal (UBC) process was also studied to produce a UBC water mixture (UBCWM) with high coal concentration. The rheological characteristics of CBWM and UBCWM have been conducted by using a stress controlled rheometer. The results indicate that the maximum concentrations of the carbonized plant, carbonized coconut cell biomass, and UBC were 35.9, 51.2, and 61.5 wt%, when respectively using 0.3 wt% of naphthalene sulfonic acid (NSF), polymethacrylate (PMA), and NSF as dispersing additives, and 0.1 wt% of carboxyl methyl cellulose (CMC) as a stabilizing additive.

05/00056 Proposal of a new rhelogical model of a highly loaded coal-water mixture (CWM): Matsuo, S. Kagaku Kogaku Ronbunshu, 2003, 29, (4), 526–533. (In Japanese)

The multi-component seismic exploration technique has drawn great attention in the petroleum industry because it enlarges the S-wave information, reduces the ambiguity in reservoir prediction, and improves the prediction and identification possibility of reservoir fluids. To push forward the application and development of the technique, the 2D and 3D multi-component technical tests have been carried out since 2002 in the Sulige Gasfield, Ordos Basin; the Guang'an Gasfield, Sichuan Basin; the Xushen Gasfield, Songliao Basin; and the Sanhu area, Basin, Qaidam Basin. The imaging of the converted wave is better than that of the P-wave for the gas-bearing structures in the deep igneous body of the Songliao Basin and the Sanhu area, and can define the reservoir boundaries more accurately. In the description of the tight sand gas reservoirs of the Sulige and Guang'an Gasfields, the converted wave imaging improves the accuracy of reservoir prediction and fluid identification, paving the way for the arrangement of wells.

Effect of Sodium Aromatic Sulfonate Group in Anionic Polymer Dispersant on the Viscosity of Coal−Water Mixtures

This paper focused on the effect of sodium aromatic sulfonate in anionic polymer dispersants on the viscosity of coal−water mixtures (CWMs) with a Tatung coal powder. To determine the optimum molecular structure of a polymer dispersant for the minimum viscosity of a CWM, various anionic co-polymers with different hydrophilic and hydrophobic groups or different molecular weights were prepared, using various types of monomers. Anionic co-polymers with sodium aromatic sulfonate, such as sodium styrene-sulfonate and sodium naphthalene-sulfonate, reduced the viscosity of dense CWMs. In particular, a co-polymer of sodium styrene-sulfonate and sodium acrylate with a molar ratio of 70:30 and a molecular weight of ∼10 000 gave the minimum viscosity of a 70 wt % CWM. To obtain a low viscosity for a CWM, a large electrostatic repulsive force with an absolute value of the zeta potential of the coal particles of >70 mV and >6.5 mg/g of adsorbed polymer on the coal surface were needed. The mixture of sodium polystyrene-sulfonate and sodium polyacrylate with a weight ratio of 50:50 also gave a low viscosity of 70 wt % CWM. On the basis of the results, the adsorption behavior of polymer dispersants on the coal surface is examined by measuring the wettability of coal powder pellets.

Properties and rheology of coal-water mixtures using different coals : Turian, R. M. et al. Fuel, 2002, 81, (16), 2019–2033

Properties and rheology of coal-water mixtures using different coals : Turian, R. M. et al. Fuel, 2002, 81, (16), 2019–2033

Development of the additives of coal water mixture : Fan, L. Riyong Huaxue Gongye, 2002, 32, (1), 46–48. (In Chinese)

As the reducing of petrol resource and the pollution of fuel coal becoming more and more hardly,water coal mixture (CWM) as a nwe unpolluted kind of caol liquid fuel have been more and more important.From 1970's to present,the abroad and civil professors have studied a lot of additives.The additives used in CWM howe two kinds:one is negative-ion surfactant and the other is non-ion surfactant,but the additives with high effective,low price and wide fitness are still very few.

Properties and rheology of coal–water mixtures using different coals

The properties, settling rates, and the rheology of coal–water mixtures (CWM) made up from different coals were investigated. Test suspensions containing different concentrations of suspended particles were made up from each of four different pulverized parent coals: a Pittsburgh Seam No. 8 coal, an Illinois coal, and the product and feed from a flotation process using an Illinois coal. All the parent coals had broad particle-size distributions. In addition, the Pittsburgh Seam No. 8 coal was classified into four different size fractions using sieving, resulting in three coarser, narrow particle size cuts and the fine residual fraction passing 325-mesh, which had a broad size distribution. The property characterizations for all coals included the following: elemental analyses, heating values, particle size analyses, particle surface areas and pore sizes, solid heat capacities, and thermal conductivities. Tests on the suspensions included detailed supernatant ion analyses, and measurements of pH values and zeta potentials. For each test coal maximum-packing volume fractions were estimated using centrifugation, and the settling rates and directly measured yield stresses, using the vane method, were determined for every concentration of coal–water mixtures (CWM) used. The shear-stress/shear-rate dependences of the test suspensions, covering the shear-rate range from 0.1 to 10 5 s −1, were determined using a capillary rheometer. For some of the test suspensions, correction for a pronounced wall-slip effect was required. Apart from the directly measured yield stresses using the vane method, yield stresses were estimated indirectly by extrapolation and rheological model-fitting. Extrapolation of directly measured yield stresses to infinite limit was used to estimate maximum packing for comparison with those determined from the irreducible sediment volumes using centrifugation. The two-parameter power-law, Bingham plastic and Casson empirical rheological models, and the three-parameter Herschel-Bulkley and Sisko models were used to fit the shear-stress/shear-rate data. In general, the shear-stress/shear-rate dependence was found to be shear-thinning, power-law, over the lower ranges of shear, and to tend to Newtonian limit at high shear; a dependence which is best described by the three-parameter Sisko model.

The rheodynamics and combustion of coal–water mixtures

Investigation methods for characteristics of movement along the tubes, combustion dynamics and gasification of separate drops were developed for the coal–water mixtures (CWM). The following parameters were determined on the basis of laser heating: thermometric, pyrometric and concentration dynamics of single-drop combustion, complete combustion times, duration of temperature phases of combustion, as well as the moment and temperature of ignition. Information on the combustion mass velocity and gasification products was also obtained using laser heating.

ＣＷＭ粒子の球状化効果の円形度による評価

Evaluation of circularity of coal particles produced by a rounding method and a wet ball mill method was performed by a flow particle image analyzer, and the effect of circularity on the fluidity of CWM (Coal Water Mixture) was investigated. The rounding method employed in the present work ground off the protrusions of particles and generated fine particles. The results showed that the circularity of Bituminous coal particles produced by the rounding method was 0.97 and the CWM with Bituminous coal particle content of 70wt% had a good fluidity of the viscosity of 0.75Pa·s. The circularity of coal particles produced by the rounding method was the same as that by the wet ball mill method under the same coal particle content in CWM. The viscosity of CWM consisting of coal particles with the circularity of below 0.95 was increased by 0.15-0.2Pa·s from that with the circularity of 0.97. Therefore the fluidity of CWM is further improved by increasing the circularity to above 0.95. These results concludes that the present rounding method gives the same circularity of coal particles as that by the wet ball mill method, which in turn yields the good fluidity of CWM with the reduction in product cost.

Maximum packing concentration of coal water mixtures

Maximum packing concentration of coal water mixtures

Preparation techniques of coal water mixtures with upgraded low rank coals

Preparation techniques of coal water mixtures with upgraded low rank coals