An experimental study of the viscosity of coal-water slurry with a bifractional composition of its dispersed phase

Abstract

At present, the Russian power industry is predomi nantly oriented at using natural gas. However, plans to increase the supplies of this fuel to European countries give rise to certain worries of whether its supplies to the domestic market will remain stable and reliable. In this connection, studies aimed at developing new or improving the traditional technologies for using coals are becoming increasingly more important. The possi bilities of integrated processing of coal and other kinds of solid fuel are well known from the results of numer ous theoretical and experimental works carried out both in Russia and abroad. Statistical data indicate that the fraction of coal in the generation of heat and electricity in many industrially developed countries is considerably higher than it is in Russia. In our opin ion, one specific feature of the Russian market of energy is that there is in fact no selection of coal utili zation technologies to pick from, due to which attempts to put some of them in use encounter diffi culties and failures.Russia has tremendous reserves of coals, which dif fer considerably in their composition and properties; therefore, different technologies adapted to both qual itative and price characteristics of fuel and to the demands of consumers must be developed.Preparation of coal-water slurries (CWSs), sub stances that are not merely a mechanical mixture of pulverized coal and water but a composite fuel having predetermined technological properties due to which minimal operational costs are achieved during its fab rication, storage, transportation, combustion, or gas ification, is one of the most promising technologies of using coal for power generating purposes. These mat ters have recently been dealt with in many works, the most interesting ones of which are concerned with development of efficient process arrangements [1][2][3][4] and simulation of processes through which coal parti cles interact with water serving as the dispersion phase [5][6][7]. High viscosity of suspension containing the required concentration of pulverized coal is the main problem encountered in using coal-water fuel. Researchers consider various parameters of CWS influencing its viscosity: content of solid phase, sus pension temperature, composition of coal, state of the surface of particles, and others. Many researchers have recognized that CWSs with a bifractional composition of the dispersed phase have better rheological charac teristics as compared with traditional fuel the pulver ized coal of which has a polyfractional composition [4]. The rheological characteristics of coal-water fuel with a bifractional composition of pulverized coal and with different sizes of coarse and fine fraction particles were studied using the previously developed mathe matical model [8] as a further development of this line. This model took into account the ratio of coarse and fine particles contained in the dispersed phase of coal-water slurry, and the influence of this parameter on the viscosity and fluidity point of suspension was stu...

Investigation of rheological properties of composite suspension fuels

“…1. Принципиальная схема экспериментального стенда для приготовления МУС и исследования его реологических свойств: 1 -бункер-питатель; 2 -вибрационная мельница; 3 -бункер для пыли; 4 -виброустановка для проведения ситового анализа; 5 -весы; 6смеситель; 7 -мерная емкость; 8 -ротационный вискозиметр; I -дробленый уголь; II -подача охлаждающей воды; III -отвод охлаждающей воды; IV -угольная пыль; V -угольная пыль на хранение; VI -угольная пыль бифракционного состава; VII -вода для приготовления ВУТ [29]. [16].…”

The Review of Ignition and Combustion Processes for Water-Coal Fuels

“…At the end of XX century the basic data about combustion of the WCF were obtained and at the same time the effective technologies of preparation and usage of water-coal slurries were created [17][18][19][20][21][22][23][24][25][26]. However, taking in account the real needs in usage of WCF, some countries with deficit of natural resources support research and development activities for improvement of water-coal technologies [2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”