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Coal water slurry is an advanced and efficient coal utilization technology, prepare coal water slurry by gasification wastewater can realize the recycling of wastewater and improve the combustion or gasification efficiency of the slurry. Stabilizer is an important component to ensure fluidity and stability in industrial applications of coal water slurry, and the complex substances in wastewater for coal water slurry preparation have a great influence on the stabilizer. Therefore, in this paper, the influence of the major substances in gasification wastewater on the stabilizer is studied. Results show that (a) Ammonia nitrogen substances have adverse effects on stabilizers, because the ionized NH4+ in the solution will bond with the polar groups on the stabilizer, which will affect the stabilizer to lose its effectiveness and reduce the stability of the slurry. (b) Small organic molecules have little effect on stabilizers, this is because the binding strength and quantity of stabilizer to water molecules is much larger than that of organic matters such as phenolic substances. (c) Highvalent metal ions have a greater impact on stabilizers, the metal ions easily form gels or precipitates with the stabilizer, causing it to lose its effectiveness, and also have an electrostatic effect with the carboxyl group on the side chain of the stabilizer, which makes the stabilizer easy to aggregate together and lose the steric hindrance effect, finally cause the stability of the slurry reduced. The conclusion of the influence of substances in wastewater on stabilizer can provide a technical reference for the selection of suitable wastewater and stabilizer to prepare coal water slurry, then promoting the efficient use of energy.

The coal gasification process produces a large amount of wastewater which is seriously polluted and difficult to biochemically treat. The regasification of coal water slurry produced from gasification wastewater meets the requirements of clean and efficient use of energy and the concept of circular economy. In this paper, the slurryability of coal water slurry prepared with gasification wastewater was measured, and the influence mechanism of organic matter, metal ions, and ammonia nitrogen components in coal gasification wastewater on slurryability has been studied. Results show that (a) Coal water slurry can be prepared with gasification wastewater, and the composition of wastewater has a great influence on the slurryability. (b) Phenols and alcohols in wastewater are not conducive to slurryability, while urethane in wastewater is beneficial for slurrying. (c) K+ and Na+ in wastewater have little effect on the slurryablity even in high concentration, while Mg2+ and Ca2+ have basically no effect on the slurryability under the concentration range of coal gasification wastewater. However, Fe3+ has a negative effect and Cu3+ has a positive effect on the slurryability at low concentrations. (d) Ammonia nitrogen can affect the slurryability of coal water slurry by affecting the pH of the solution. NH4OH solution is alkaline, which is conducive to slurrying, while (NH4)2SO4 and NH4Cl solutions are acidic, resulting in poor slurryability of coal water slurry. [ABSTRACT FROM AUTHOR]

A variety of wastewaters can be generated in the coal chemical industry, and their treatment processes are complicated and have difficulty meeting standards. Using wastewater to prepare coal water slurry is an efficient and convenient new approach. The concentration of coal wastewater slurry is related to the content of the main wastewater components. A backpropagation neural network is developed to predict the maximum slurry concentration and analyze the mechanism at the data level according to the main component indicators, and a particle swarm algorithm is used to improve the neural network. The results are as follows: (a) it is feasible to predict the maximum concentration of coal wastewater slurry by a neural network, and a particle swarm algorithm can effectively improve the prediction accuracy in different models, reducing mean absolute error by up to 0.44%; (b) different input factors have different impacts on model prediction results—organic matter, ammonia nitrogen, and monovalent metal ions content as input factors to predict the maximum slurry concentration can get the most accurate results, obtaining a mean absolute error of 0.16% for the optimized backpropagation neural network and the lowest mean square error; and (c) divalent metal ions and phenols content are not suitable as input factors for predicting, as they all cause an increase in model error due to their weak or complex effects on the slurryability. [ABSTRACT FROM AUTHOR]

Coal water slurry technology and gasification technology are used to simultaneously treat wastewater and CO2; coal water slurry is prepared from fixed‐bed coal gasification wastewater; and then, thermogravimetric analysis, Fourier‐transform infrared spectrometry, scanning electron microscopy, energy‐dispersive spectrometry, and X‐ray diffraction are used to analyze the characteristic parameters of CO2 gasification and the products that formed. The results reveal the following: (a) compared with coal water slurry, coal gasification wastewater slurry shows decreases in the gasification start temperature, gasification weight loss peak temperature, and gasification end temperature of 12°C, 22°C, and 17°C, respectively, and shows increases in the maximum and average reaction rates. In addition, the reactivity index for coal gasification wastewater slurry is found to be 14.29% higher than that for ordinary coal water slurry. (b) Coal gasification wastewater slurry produces more methane and other aliphatic hydrocarbon gases in the pyrolysis stage and more CO in the coke gasification stage than coal water slurry. (c) Coal gasification wastewater slurry contains many small particles and flocs on the surface of the coal and a high Na content (up to 8.07%) in the microarea. In addition, a richer pore structure exists on the surface of the gasification residue of the coal gasification wastewater slurry. (d) The components of the gasification residue for coal gasification wastewater slurry show relatively larger changes. Moreover, the catalytic effect of alkali metal may be weakened due to the reaction of the minerals in the coal to form a complex. [ABSTRACT FROM AUTHOR]

Abstract: Bioferment residue of drugs (BRD) is one kind of harmful and hazardous substance which has complex compositions. Thus, proper treatment of these residues has become an important concern. BRD can be utilized harmlessly and economically by mixing it with coal powder, water, and dispersant to prepare slurry fuel, named as coal‐BRD‐slurry (CBRDS). In this study, the influence of BRD on the slurry ability and combustion behaviour of CBRDS was investigated with coal water slurry (CWS) as reference. Results showed that the dispersant can reduce the slurry viscosity of CBRDS and CWS, and its optimum dosage was 0.6 wt% on the dried coal basis. The fixed‐viscosity concentration of CBRDS decreased with increasing BRD dosage. CBRDS and CWS exhibited shear‐thinning behaviour. The rheological behaviour was fitted by the power law. CBRDS exhibited higher apparent viscosity and stronger shear‐thinning behaviour because of the flocculent structure and well‐developed pores of the BRD. BRD can improve the stability of CWS by decreasing solid‐liquid separation of the slurry. Addition of BRD decreased the ignition temperature and increased the ash residues, suggesting a synergistic effect of CWS and BRD occurred during the combustion of CBRDS. [ABSTRACT FROM AUTHOR]

Abstract: Coal gasification wastewater (CGW) contains high concentrations of pollutants and varying chemical components and thus is difficult to treat. CGW slurry (CGWS), which is prepared by blending coal, CGW, and additives, is a new wastewater utilization technology that can be used to efficiently and conveniently treat CGW. This work mainly investigated the slurryability, rheology, stability, and combustion properties of CGWS prepared from Shenhua and Yima coals. Results showed that (a) the maximum solid loading of CGWS was slightly lower than that of ordinary coal–water slurry (CWS), but CGWS exhibited better pseudoplastic rheology and stability than CWS; moreover, increasing the solid loading of CGWS resulted in an increasingly pseudoplastic trend and enhanced stability; (b) CGW strengthened the combustion capacity of coke and CGWS demonstrating better ignition, burning, and burnout properties than CWS. These findings suggest that the use of CGWS technology in CGW treatment is beneficial economically and environmentally. [ABSTRACT FROM AUTHOR]