CC BY
84
https://doi.org/10.29013/AJT-20-3.4-15-22
Ergashev N. A., Senior teacher Isomidinov A. S., Senior teacher,
"Ferghana polytechnic institute" Republic of Uzbekistan E-mail: [email protected]
Alimatov B. A., doctor of technical sciences, professor "Belgorod State University of Technology named after B. G. Shukhov" Russian Federation
DETERMINATION HYDRAULIC RESISTANCE OF DEVICE THAT HAS THE VORTEX FLOW CREATING CONTACT ELEMENT
Abctract. In the article, results of experiments which were carried out in wet dusty gas cleaning device for determination of total hydraulic resistance are given. For experiment's results processing scheme was designed. In experimental device hydraulic resistance that influences to the dusty gas velocity and the liquid. On basics of experiments local resistance coefficient in metallic tube and resistance coefficient in contact element were determined.
For experimenting different parameters were selected: hole in the filter material has different diameters d = 2; 2, 5; 3 mm; velocity of gas in the apparatus v== 7.07 ^ 28.37 m/s (The velocity range is close to the speed range imposed on dust-cleaning devices in industry-wide wet methods); The experiments were conducted in air and water systems at a temperature of 20 ± 2 °C.
Keywords: wet method, vortex flow creating element, dusty gas, surface tension, toxic gas, air flow, gas flow, gas velocity.
Introduction [5; 6; 7 and others]. However, a complete solution
One of the main features of the design is the im- for achieving maximum cleaning efficiency and
provement of design schemes based on the selection maximizing performance at minimum hydraulic re-
of the optimal values of resistance of the working sistance values has not been developed.
bodies of the device to the dust gas flow in the wet A general study of these problems has been made,
gas treatment facilities.This characteristic determines a wet gas purification device with a contact coil [2]
the hydraulic resistance of the device and the permis- has been developed, and a three-step research to de-
sible amount of working fluid leaving the unit with termine the effect of hydraulic resistance and purifi-
gas [1; 3; 4]. In addition, increased hydraulic resis- cation efficiency and energy consumption. In (figure
tance in the working body of the unit can improve 1), an overview of the experimental device is given.
the efficiency of cleaning, but also result in reduced Research object and method
performance and compression of dust particles into Pressure loss is observed in the working bodies
pipes. This in turn increases energy consumption. of wet gas cleaning devices. This is explained by the
Numerous research works have been carried structure of the device and the number of working
out to determine the optimal values of these factors bodies.
The contact element consists of a metal pipe 3 that directs the flow of the gas and a contact element 15 with a rotating spin on the gas flow. This condition is called loss of pressure in working bodies.
Then the total hydraulic resistance of the device can be written as follows, Pa;
AP = p + P2, (1)
where: <P - total hydrolic resistance of device, Pa; P1 - hydrolic resistance in dictance between insurge flow of gas to the device and by the vortex flow creation contact element, Pa; P2 - hydrolic resistance that in the vortex flow creating tool of device, Pa.
Figure 1. Total view of experimental device:
1 - fun; 2 - electromotor; 3 - metallic tube; 4, 10, 19 - flange; 5 - dust loading device; 6 - feeding uni; 7, 18 - Prandtl tube; 8 - insurge nipple of dusty gas; 9 - shiber; 11 - pump; 12 - tap; 13 - rotameter; 14 - water supplying tube; 15 - vortex flow creating contact element; (swirler) 16 - water spraying nipple; 17 - water entrain-ment trap; 20 - anemometer; 21 - latr; 22 - tachometer
For the determination of hydraulic resistance in It has been studied that the total resistance co-working bodies, the Darcy-Weissbach equation is efficient of a contact element bending current de-
used, Pa [8].
AP = %
P? -u
(2)
where p - gas density, kg/m3; v^ - lost gas velocity in working bodies of device, m/sec; | - hydraulic resistance which impacts to the gas flow in working bodies.
Determination and calculation of resistance coefficients are complex and require different deviations, which can only be found by experiment.
pends on the above factors. In this case, it is possible to write the equation of determining the total resistance coefficient of the working body on the dusty gas flow in the unit.
^gen + ^2 , (3)
where % - the local resistance coefficient of the dust gas to the inlet device and the contact element forming the heater is determined by the following equation;
2
*=4
(4)
=
where l - tube length, m; de - equivalent diameter of tube, m; A - The coefficient of the Darcy is that it depends on many factors in expressing the law of change with the empirical equations. Based on the structure of the experimental apparatus, the definition of the Darcie coefficient in the equation by Blazius's law was introduced [8]. Then equation (4) will look as follows;
0.316432/
da VRë
(5)
Results of experiments
In the first phase of the study, the local resistance coefficients and the values of the change factors in the distance to the inlet device and the contact element forming the heater based on equation (5) were determined experimentally. The values of the resistance coefficients and the variables are presented in (Table 1).
Table 1.- Dependence of the local resistance coefficient on the contact factor with the changing factors
u, m/s 7.07 15.45 22.48 24.32 28.37
8> Re 5 • 104 1.2 • 105 1.6 • 105 1.8 • 105 2 • 105
l, mm 1000 1000 1000 1000 1000
d mm 100 100 100 100 100
0.7 0.62 0.65 0.7 0.7
As can be seen from the values in (Table 1), the local resistance coefficients in the metal pipe are close to each other at different values of the variables. Then the coefficient of local resistance is assumed to be 0,7 with sufficient accuracy and average.
% - the resistance coefficient of the contact element that forms the heap. Determination and calculation of resistance coefficients are complex and require different deviations, which can only be found by experiment. In this case, the following
equation was obtained and the correction coefficient was used to determine the ratio of the total surface of the contact element shields to the flow-through area. The contact element is shown in (Figure 2).
e a 7 4nR2 = Ak-, (6)
nab sin P
where n - number of impellers; a, b - length of impeller's butt; ft - surface's angle of slope; Ak - correlation coefficient.
Figure 2. Total view of contact element
1 - impeller; 2 - cycle; 3 - stiffening hole
The resistance coefficient values for the contact element were calculated experimentally based on equation (6) for different values of the variables. In angle of slople for gas passage surface is sin fi = 60o contact element has resistance coefficient = 1.1 and angle of slope for gas passage surface is sinfi = 45o contact element has resistance coefficient %2 = 1.3 and correlation coefficient Ak = 0.91. And last but not least angle of slope for gas passage surface is sinfi = 30o contact element has resis-
tance coefficient = 1.5 and correlation coefficient Ak = 0.68.
In angle of slope is sinfi = 60 o the total resistance of the device is I = 1.8; in sinfi = 45 o total resistance
^gen ' I
coefficient is I = 2 and in sinfi = 30 o total resistance
^gen I
coefficient is = 2.2 are proved experimentally. Figure 3-4 illustrates the correlation coefficient of correction of the resistance coefficient and the slope of the slope of the surface of the gas with the resistance coefficient.
Figure 3. Dependence of total resistance coefficient with the correlation coefficient
Figure 4. Dependence of total resistance coefficient E
with gas passage surface's angle of slope
gen
Graphs 3, 4 are obtained through the method [10] and determined folowing formulas;
1) Dependence of the total resistance coefficient t to the correlation coefficient Ak
^gen
y = 1.7293* + 0.6165-R2 = 0.9944, (7)
2) On the dependence of the total resistance coefficient ^ to the slope of the surface of the gas by the flow of raw gas.
y = 0.0133* + 1.4 R2 = 0.9978. (8) Using the experimental values obtained in the second step, the hydraulic resistance of the given
device was not fluid, and the hydraulic resistance of the given device was experimentally determined.
Hydraulic resistance of a non-liquid device vortex flow creating element's angles of slope a = 30 °; 45 ° and 60 number of impllers which gives movement to the gas n = 12; air density 1.29 kg/m3, gas velocity v = 7.07 ^ 28.37 m/s with step is increased 4 m/s; experiments had been carried out in 20 ± 2 °C temperatures.
Experiments results are given on (figure 5).
Figure 5. Dependance of gas velocity changes on hydrolic resistance AP in without liquid supplying apparatus
Figure 5 shows that if operating part of contact elemen has the folowing angles 30 45 ° and 60 ° hydraulic resistances were changed from 12Pa by 21.2 Pa and in high diapazone of gas velocity hydraulic resistances were had the 270 Pa to 470 Pa changes.
At a small value of the gas velocity supplied to the unit, the flow is sparse and the pressure loss in the unit is close to each other, as the gas velocity increases, the flow is compacted and the hydraulic resistance increases.
The following empirical formulas, obtained by the least squares method of the graph dependencies presented in (Figure 5) [10], are obtained;
Dependence of gas velocity v g on hydraulic device on DPs on hydraulic resistance;
1) y = 0.6176x2-9.8756x + 51.272; R2 = 0.99897, (9)
2) y = 0.7627x2-11.63x + 60.998; R2 = 0.998, (10)
3) y = 1.0398x2-17.921x + 97.084; R2 = 0.9983. (11)
The working fluid leaking from the circuit breaker 16 on the device is hit by a retractable barrier 17 and spreads evenly across the wall of the unit. The flattening of the working fluid along the wall of the device provides a contact element with a rotating flow of dust and gas entering the unit through the ventilator 1, and a sliding fluid film is formed on the inner walls of the unit. Dust gas is hit at the corner of the blanket film formed on the wall of the device and is in contact with the working fluid and the working liquid retains dust particles. The purified gas is released into the atmosphere. The
resulting sludge flows from the device to the sludge stack through the trunk.
The thicker the film layer, the better the cleaning efficiency. But hydraulic resistance causes an increase. In addition, the film thickness causes an increase in the amount of liquid leaking out of the device with the purified gas. The boundary of the film is linear. Investigating the film layer is a complex process, which usually takes into account the hydraulic resistance of the device and the amount of fluid consumed in the study of the dependence of the treatment efficiency on the film thickness [9]. As the film thickness was not the main purpose of the research work, the hydraulic resistance of the given device was investigated depending on the amount of fluid consumed.
In the third step, the hydraulic resistance of the fluid-injected device was experimentally determined.
The study was conducted in various parameters and within the following limits: The slope of the unit with a slope of contact elements moving inward to the gas flow a = 30 °, 45 0 and 60 °; number of shovels perpendicular to the contact element gas flow n = 12; The diameter of the liquid-dispersing strainer hole is dh = 2; 2,5 and 3 mm; fluid consumption Q1iq = = 0.07 ^ 0.327 m3 / h (in experiments the intermediate step was increased by 0.044 m3 / h); gas density p = 1.29 kg / m3; gas velocity vg = 7.07 ^ 28.37m/s (experimentally increased with 4 m/s); the external temperature was chosen 20 ± 20 ° C for the gas and water system.
Comparative graphs for low and high hydraulic loads are constructed considering the multivariate experiments. The results of the experiments are presented in (Figures 6; 7 and 8).
1000
800
600
40Ü
200
JP/g, Pa
ö\
5 4V \ jMT
\ 2
3
10
15
20
25
30
t^ms
Figure 6. dependance of gas velocity ur on hydrolic resistance APc in the liquid spraying apparatus, a = 60 const
n 1 - dh= 2 mm Q4.q= 0.07m3/h; in 2-dh = 2.5 mm Q = 0.071 m3/h; in 3-dh = 3 mm Q1iq = 0.072 m3/h; in 4-dh = 2 mm Q^. = 0.253 m3/h;
in 5-dh = 2.5 mm Q^ = 0.295 m3/h; in 6-dh = 3 mm Qiq = 0.327 m3/h;
Figures 6, 7 and 8 showes that when gas velocity least loading. For the minimal liquid flowrate
is v= 7.07 ^ 28.37 m/s interval with the step 4 m/s dh =2 mm. Q1iq = 0.07 m3/h-const for APg= 27.4 ^
and angles of slope of contact element a = 30 °;45 ° ^ 627.5 Pa, dh =2.5 mm. Q1iq = 0.071 m3/h -const
and 60 ° are increased hydraulic resistance had for APg= 29.8 ^ 658.9 Pa.
1000
soo
600
400
200
APfg> Pa
6 \
J \ 4A \ v \
/
s 2 \
"3
5 10 i5 20 25 30
y^m/s
Figure 7. Dependance of gas velocity ur on hydrolic resistance APc in the liquid spraying apparatus, a = 450 - const
In 1 - dh = 2 mm Qiq = 0.07 m3/h; in 2 - dh = 2.5 mm Q = 0.071 m3/h; 3 - dh = 3 mm Q = 0.072 m3/h; in 4 -dh = 2 mm Qiq = 0.253 m3/h;
sh * sh * sh * sh
dA = 2.5 mm Q.= 0.295 m3/h; in 6 - dh = 3 mm Q -
APfc Pa
1200
1000
soo
600
400
200
6
5A \ 4 A \ J
/ 1
j
5 10 15 20 25 30
yarn's
Figure 8. Dependance of gas velocity ur on hydrolic resistance APc in the liquid spraying apparatus, a = 30 0- const
In 1 - dsh = 2 mm Q_u = 0.07m3/h; in 2 - dsh = 2.5 mm = 0.071 m3/h; in 3 - dh = 3 mm Q^ = 0.072 m3/h;
in 4 - dsh = 2 mm Q. = 0.253 m3/h; in 5 - dsh = 2.5 mm Q. = 0.295 m3/h; in 6 - dsh = 3 mm Q. = 0.327 m3/h;
High hydraulic resistance for maximum fluid 4) y = 0.6242 x 2 + 15.003* - 90.469; R2 = 0.9978 (21)
consumption dm = 2 mm. Q = 0.253 m3/h -const for AP = 45.9 - 978.5 Pa, dh = 2.5 mm. Q = 0.295 m3/h -
fg ' sh ^-tiq
-const for APf = 47.8
fg
1003.2 Pa and d, = 3 mm.
Qh = 0.327 m3/h-const for APgg= 49.8 - 1028.3 Pa.
The following empirical formulas were obtained using the least squares method of graphical dependencies presented in (Figures 6; 7 and 8).
Depending on the hydraulic resistance of the working body of contact elements moving in a gas flow v^ and angle of slope contact element; a = 60 ° - const
1) y = 0.5754*2-0.3434* + 0.5387; R2 = 0.9996(12)
2) y = 0.5892 x 2 + 0.2554* - 2.3743; R2 = 0.9998 (13)
3) y = 0.6089 x 2 + 0.5873* - 3.0193; R2 = 0.9997 (14)
4) y = 0.7587*2 + 6.4326* - 38.56; R2 = 0.9998 (15)
5) y = 0.733*2 + 9.1652* - 52.343; R2 = 0.9998 (16)
6) y = 0.733*2 + 9.1652* - 52.343; R2 = 0.9998 (17)
a = 45 ° - const
1) y = 0.6158*2 + 2.6351* - 16.762; R2 = 0.9983 (18)
2) y = 0.6248 x 2 + 3.3384* - 19.484; R2 = 0.9992 (19)
3) y = 0.629 x 2 + 4.2042* - 23.17; R2 = 0.9997 (20)
5) y = 0.7804 x 2 + 11.375* - 62.745; R2 = 0.9984 (22)
6) y = 0.8771 x 2 + 9.0507* - 48.405; R2 = 0.9996 (23)
a = 30 ° - const
1) y = 0.5754 x 2-0.3434* + 0.5387; R2 = 0.9996 (24)
2) y = 0.5892 x 2 + 0.2554* - 2.3743; R2 = 0.9998 (25)
3) y = 0.6089 x 2 + 0.5873* - 3.0193; R2 = 0.9997 (26)
4) y = 0.7587 x 2 + 6.4326* - 38.56; R2 = 0.9998 (27)
5) y = 0.7401 x 2 + 7.9696* - 46.473; R2 = 0.9998 (28)
6) y = 0.733 x 2 + 9.1652* - 52.343; R2 = 0.9998 (29)
Conclusion
From the three-stage experiments on hydraulic resistance, we can conclude that increased fluid intake strengthens the liquid film on the inner surface of the pipe. This in turn increases the hydraulic resistance. In addition, the increase in gas velocity supplied to the unit significantly influences hydraulic resistance. Increased hydraulic resistance improves cleaning efficiency but increases energy costs for dust gas cleaning. Therefore, achieving high purification efficiency at minimum hydraulic resistance values is an important issue.
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