ТЕKA. COMMISSION OF MOTORIZATION AND ENERGETICS IN AGRICULTURE – 2012, Vol. 12, No.4, 19-22

Experimental research of hydrotransporting concentrated residues at solid fuel burning

Nataliya Chernetskaya-Beletskaya, Aleksandr Kuschenko, Denis Kapustin

Volodymyr Dahl East- Ukrainian National University, Lugansk, Ukraine

S u m m a r y . The article presents data of experimental studies that determine the pressure losses and the effective coefficients of linear losses on friction and local resistance at transportation of ash concentrated wastes that show abilities of non-Newtonian fluid in the steady state of constant pipeline diameter, which has a straight portion and turns on 900 and 1800.

K e y w o r d s : non-Newtonian fluid, ash concentrated wastes, transportation, coefficients.

INTRODUCTION

Implementing energysaving technologies and improving energy efficiency of used systems and complexes is actual task in the world of economic uncertainty and rising cost of main energy sources.

About 30% of all electric energy is produced by power station in Ukraine, where disposal of solid residues is organized by hydraulic ash removal systems (HARS). One of the major shortcomings of such systems is low efficiency hydraulic transport due to big amount of liquid per unit of transported material (up to 50-80 m3 of water per one ton of solid material). Expenses on restraining hydraulic ash removal are about 7,8 – 11,2 million per year and even more, depending power station intensity[Putilov 15].

One of the main directions of HARS efficiency development is increasing the content of transported material that leads to structure formation in condition of large number of fine-dispersed fractions. In this case ash (ash-cindery) hydraulic mixture obtains abilities of non-Newtonian liquids [Kapustin 8, Uriev 20].

The key hydraulic transport indexes changes occur not uniformly depending on transported material concentration that is necessary to consider at systems exploitation.

OBJECTS AND PROBLEMS

The research of increasing the concentration of solid component at ash-cindery wastes transporting was occurred by USIHydrocoal and USIHydrotehnics on the territory of Ukraine and UIS. However, the impact of solid material on the rheological properties was not taken into account [Dobkin 6, Svitlyi 19].

The aim of the article is experimental determination of head losses, coefficients of friction losses and local resistances at concentrated ash hydraulic mixture with abilities of non-Newtonian fluid flow.

Experimental determinations of pressure losses were made on bases of data of the piezometeris’s display at different transporting speeds [Chernetskya-Beletskaya 4]. According to test results was constructed based friction losses and local resistance of the effective Reynolds number for direct plot, turn on by 900 (fig. 1) and 1800 at concentrations of solid material 40, 50, 60%.

The analysis of the data showed that increasing of the movement resistance to the straight section and horizontal turn by 1800 occurs throughout the study area and is close to linear.

But most interesting are the experimental dependences of resistance on vertical elbow 900,

20 NATALIYA CHERNETSKAYA-BELETSKAYA, ALEKSANDR KUSCHENKO, DENIS KAPUSTIN

which are characterized by increasing head losses at reducing average transportation speed from 0,8 to 0,5 m/s (accordingly 40Re 12000 26000е ,

50Re 600 1400е , 60Re 90 200е ). The calculation of the linear losses

coefficient e for concentrated ash hydraulic mixture was made on the basis of experimental data results on determining hydraulic friction losses:

22

еw

D pL u

, (1)

where: D - diameter of pipeline, m; w - density of slurry, kg/m3;

L - length of pipeline, m; p - pressure losses, Pa;

u - speed of slurry, m/s. It was found that the effective coefficient of

linear friction losses e with increasing effective Reynolds number decreases (fig. 2.). However, this decrease is not linear and at confidence probability of 95% (confidence interval is no more than 0,0073) corresponds to approximating dependencies in the next form:

2/ ln Reе еa b , (2)

where: =0,0123С - 0,7124a , -0,1429С + 9,897b - coefficients dependent on

the mass concentration of solid material in hydraulic mixture.

Fig. 1. Dependence of the resistance to turn of the pipeline by 900 on the effective Reynolds number 1, 2, 3 accordingly for concentrations of 40, 50, 60%

0,03

0,04

0,05

0,06

0,07

0,08

0,09

0,1

0,11

0,12

10 100 1000 10000 100000 Ree ?

λе

123

Fig. 2. Dependence of the effective coefficient of linear friction losses from effective Reynolds number 1, 2, 3 accordingly for the concentration of 40, 50, 60%

EXPERIMENTAL RESEARCH OF HYDROTRANSPORTING CONCENTRATED RESIDUES AT SOLID FUEL BURNING 21

0

10

20

30

40

50

60

10 100 1000 10000 100000 1000000 Ree ,

ςe

1

2

3

4

5

6

Fig. 3. Dependence of the effective coefficient of local resistance for pipeline’s turn by 1800 (1, 2, 3) and 900 (4, 5, 6) from the effective Reynolds number accordingly for the concentration of 40, 50, 60%

The effective coefficient of local resistances e at hydraulic mixture flow in molded parts was

defined together with coefficient e for linear pipeline section.

Dependencies for determination e from the effective Reynolds number for vertical turn by 900 are similar to the horizontal turn by 1800 and are described in alike form of mathematical expressions. This means that the similar processes occur in them.

Obtained in the experiment data with confidence probability of 95% (confidence interval is not more than 0,057) to approximating stepwise dependence in the form

Ren

е еm (3)

where: 37,57 4,44

180Cm e

,

2

180

48,51,89

320C

n

- factors that depend on mass concentration of transported material for horizontal turn;

5 790 2,99 10 4,96 10m C ,

2

90

511,74

245C

n

- for vertical turn.

Changes of effective local resistance

coefficients have strong stepwise characteristic and inflate at mass concentrations over 50%.

CONCLUSIONS

The experimental researches allow making the following conclusions:

- dependences of head losses changes from effective Reynolds number for straight section and turn areas by 1800 are close to the linear because of local destruction at transportation speed increasing.

- head loss difference from effective Reynolds number for vertical elbow by 900 have extremes in speed range 0,5-0,8 m/s ( 40Re 12000 26000е , 50Re 600 1400е ,

60Re 90 200е ), that is caused by the formation of immovable layer on the pipeline bottom.

- effective coefficient of friction losses, depending on the effective Reynolds number decreases non-linearly through the whole range of measurements for all concentrations of solid component, and effective local resistance coefficients for turn by 900 and 1800 in the same conditions increase by step law, that shows the steady-state flow.

REFERENSES

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ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ ПАРАМЕТРОВ

ГИДРОТРАНСПОРТИРОВАНИЯ ТВЕРДЫХ ОТХОДОВ ТЭС

Наталья Чернецкая-Белецкая, Александр Кущенко, Денис Капустин

Аннотация. В статье представлены материалы экспериментальных исследований по определению потерь давления и эффективных коэффициентов линейных потерь на трение и местные сопротивления при транспортировании концентрированных золовых отходов, которые проявляют свойства неньютоновской жидкости, в установившемся режиме по трубопроводу постоянного диаметра, который имеет прямолинейный участок и повороты на 900 и 1800. Ключевые слова : неньютоновская жидкость, зола, концентрированная гидросмесь, транспортирование, коэффициенты.