DETERMINATION OF LOAD RANGE FOR GAS AND LIQUID PHASES IN ROTOR-FILTER APPARATUS

АННОТАЦИЯ

В статье представлены результаты исследования, проведенного по определению количества капель жидкости, уносимых газом, и потребляемой при этом механической энергии в роторно-фильтрующем аппарате для мокрой очистки запыленных газов. Исследования проводились в следующих пределах варьируемых параметров: расход жидкости S_воды=0,141; 0,168; 0,178 м³/ч, диаметр соплового отверстия d_н=1; 2; 3 мм, скорость газа υ_г=5 м/с ÷ 25 м/с, промежуточная ступень 5 м/с, активная поверхность фильтрующего сетчатого материала ∑S_акт=0,202; 0,229; 0,268 м², частота вращения ротора для проведения эксперимента задавалась средним значением n=25 об/мин, плотность газа по воздуху ρ_г=1,29 кг/м³ и плотность воды ρ_г=1000 кг/м³.

При самостоятельном питании роторного фильтра жидкостью из жидкостной ванны наблюдалось увеличение механических энергозатрат при улавливании пыли. Установлено, что наибольшие энергозатраты наблюдались при улавливании пыли, имеющей высокую вязкость при смешивании с водой.

ABSTRACT

The article presents the results of a study conducted to determine the amount of liquid droplets entrained in the gas and the mechanical energy consumed in the process in a rotor-filter apparatus for wet cleaning of dusty gases. The studies were conducted within the following limits of variable parameters: the liquid flow rate S_water=0.141; 0.168; 0.178 m³/h, the diameter of the nozzle hole d_n=1; 2; 3 mm, the gas velocity υ_g= 5 m/s ÷ 25 m/s, the intermediate step is 5 m/s, the active surface of the filtering mesh material ∑S_act=0.202; 0.229; 0.268 m², the rotor rotation frequency for the experiment was set at an average value of n=25 rpm, the gas density for air ρ_g =1.29 kg/m³ and the water density ρ_g =1000 kg/m³.

When the rotor filter is self-supplied with liquid from the liquid bath, an increase in mechanical energy consumption during dust capture was observed. It was found that the greatest energy consumption was observed when capturing dust that has a high viscosity when mixed with water.

Ключевые слова: ротор-фильтр, рабочая жидкость, вязкость, газ, скорость, гидравлическое сопротивление, количество капель, механическая энергия.

Keywords: rotor-filter, working fluid, viscosity, gas, speed, hydraulic resistance, amount of drops, mechanical energy.

Introduction. One of the factors limiting the high gas velocity range of wet gas cleaning devices is associated with the ejection of a working fluid droplet from the device, which is explained by the removal of a certain amount of liquid from the contact zone of the liquid and gas [1,2,3].

The detection of a drop of working fluid is determined experimentally, depending on the operating mode of the device and under conditions of changing various parameters.

In addition, the formation of the Koanda effect along the working surface of the rotor also depends on the amount of liquid supplied to the device and the speed of the dust gas.

Research object. Based on the above, the liquid droplet ejection at low and high loads of dust-gas velocity was experimentally determined. A rotor-filter device was chosen as the object of research (Fig. 1) [1,4].

1–diffuser; 2–cylindrical body; 3–confuser; 4–working fluid nozzle; 5–probe; 6–rotor-filter; 7–liquid bath; 8–sludge pipe; 9–straightening pipe.

Figure 1. Construction scheme of the rotor-filter device

The rotor-filter device consists of a rotating rotor and a filter mesh material coated on its upper part, a diffuser that directs dusty gases perpendicular to the surface of the filter mesh material, a nozzle that disperses the liquid by ejection, an umbrella that evenly spreads the liquid on the filter surface, a cylindrical body equipped with a bath and a sludge pipe for collecting the working fluid, and a confuser that releases the cleaned air into the atmosphere. When the dusty gas flow moves through the diffuser and hits the filter surface perpendicularly, it is cleaned of dust particles in the liquid film formed on the working surface of the filter. The cleaned gas is released into the atmosphere through the confuser.

The main advantage of the rotor-filter device over existing wet dust gas cleaning devices is that, firstly, due to the rotation of its rotor, the working surface changes quickly and ensures an increase in the contact surface of the filter, and secondly, the flow of dusty gas moving through the diffuser is cleaned on the outer A and inner B working surfaces of the filter, which improves the dust cleaning efficiency of the device.

Results of theoretical and experimental research. The research is in the following limits of variable parameters: the liquid flow rate S_water=0.141; 0.168; 0.178 m³/h, the diameter of the nozzle hole d_n=1; 2; 3 mm, the gas velocity υ_g= 5 m/s ÷ 25 m/s with an intermediate step of 5 m/s, the active surface of the filtering mesh material ∑S_act=0.202; 0.229; 0.268 m², the rotor rotation frequency was set at an average value for the experiment n=25 rpm, the gas density for air ρ_g=1.29 kg/m³ and the water density ρ_g=1000 kg/m³ [1,5,6].

The dimensions obtained as a result of the research are shown in pictures 2, 3 and 4.

1-d_n=3 mm; 2- d_n =2 mm; 3- d_n =1 mm;

Figure 2. The graph of the dependence of the gas velocity on the relative value of the liquid droplet exit: S_l=0.141 m³/hour const.

1-d_n=3 mm; 2-d_n=2 mm; 3-d_n=1 mm;

Figure 3. The graph of the dependence of the gas velocity on the relative value of the liquid droplet exit: S_l=0.168 m³/hour const.

1-d_n=3 mm; 2-d_n=2 mm; 3-d_n=1 mm;

Figure 4. The graph of the dependence of the gas velocity on the relative value of the liquid droplet exit: S_l=0.178 m³/hour const.

Analysis of the research results in Figures 2; 3 and 4 shows that increasing the gas velocity increases the droplet ejection. In addition, changes in the nozzle diameter and the physicochemical properties of the liquid in the object under study also affect the droplet ejection. For example, with an increase in the nozzle diameter, the droplet diameter increases and its settling velocity increases. In this case, the droplet ejection decreases. However, the liquid film formed on the rotor surface is destroyed. This reduces the cleaning level of the device. On the contrary, a decrease in the nozzle diameter reduces the droplet diameter and increases the cleaning efficiency of the device. However, the droplet ejection increases. In addition, an increase in the viscosity of the liquid also affects the droplet ejection. In the design of devices for cleaning dusty gases by wet method, according to the regulations, the permissible value of the droplet exit when the liquid speed is 5-25 m/s should not exceed S = 0.1÷ 0.2 kg/kg.

2; 3 and 4 - it can be seen from the graphic relationships in the pictures that gas velocity υ_g=10÷20 m/s, liquid consumption S_l=0.150÷0.170 m³/h, water density ρ_g =1000 kg/m³, nozzle hole diameter d_n=2.5÷3 mm, and filter mesh material active surface ∑S_act=0.25 m² satisfy the specified requirement.

Based on the above, experiments were conducted by changing the physical properties of the liquid within the specified parameters. In this case, by adding 10, 15 and 20% soda ash (Na₂CO₃) to water, the gas velocity was increased. υ_g=10÷20 m/s in the range of droplet exit was determined. Experiences in the upper range of fluid consumption S_l=0.170 m³/hour was carried out.The experimental results are presented in Figures 5 and 6.

1-Na₂CO₃  10% in mass share; 2-Na₂CO₃  15% in mass share; 3-Na₂CO₃  20% in mass share;

Figure 5. The graph of the dependence of the gas velocity on the relative value of the liquid droplet exit: d_n=2.5 mm and S_l=0.170 m³/h const.

1-Na₂CO₃  10% in mass share; 2-Na₂CO₃  15% in mass share; 3-Na₂CO₃  20% in mass share;

Figure 6. The graph of the dependence of the gas velocity on the relative value of the liquid droplet exit: d_n=3 mm and S_l=0.170 m³/h const.

Figures 5 and 6 show that the drop does not exceed the permissible limit when the speed range is 5÷20 m/s. In this case, the diameter of the nozzle hole d_n=2.5 mm and the liquid flow rate should not exceed S_l=0.170 m³/h. With an increase in gas velocity of 20 m/s, the droplet output exceeds the permissible value.At a gas velocity of 5–15 m/s, the surface area of ​​the film layer on the rotor surface covered by the liquid flow is almost equal to the active surface and its thickness is also sufficient.

From the analysis of the data, it can be assumed that if the rotor of the apparatus continues to partially provide the self-absorption effect from the liquid in the bath, it will lead to an increase in the viscosity of the liquid. This will make it more difficult for the drop to escape. This leads to the conclusion that it is possible to increase the gas velocity. Since increasing the gas velocity does not radically increase the liquid exit from the apparatus. In this case, zones A and B of the apparatus are of great importance [7].

The study implies the need to conduct a study on droplet discharge depending on the physico-chemical properties of the liquid used in data processing cleaning. This condition also depends on the amount of dust in the gas.

Based on the results of the research, the experimental values ​​were processed, and the following empirical equation was recommended to determine the amount of liquid detector exit from the apparatus in the range of gas velocity 5÷25 m/s.

                                                     (1)

where ∆k is a correction factor related to the viscosity of the liquid, which can only be determined experimentally.

The research results differ from the theoretical calculation results by 4.2% and do not exceed. The values ​​in equation (1) are meaningful when the gas velocity is 5÷20 m/s and S_l=0.170 m³/h when has meaning.

Within the specified limits, the difference of the research results according to the equation (1) does not exceed 4.5% on average compared to the calculated results, which means that the obtained experimental results are correct.Such accuracy is sufficient for practical calculation of droplet discharge, and equation (1) is recommended for engineering practice.

From the analysis of equation (1), it is known that the gas velocity, the diameter of the nozzle hole and the physico-chemical properties of the working fluid have a significant effect on the droplet exit. These variables affect the relative value of droplet output by affecting droplet diameter and mass.

[8,9] The authors' research shows that the droplet ejection rate increases due to the droplet hitting the working parts of the device and breaking up into microdroplets, which leads to an increase in the number of small droplets leaving the device along with the gas. Thus, increasing the viscosity, density, and surface tension of the liquid reduces the formation of secondary fine particles. Particles of large size and mass have sufficient potential energy, so they do not pass into the gas stream and do not escape from the device.

Droplet leakage is the main parameter in determining the upper limit of gas loading of the device for the design being studied. In addition, the rotating elements in the dynamic dust collectors create a vitellation effect, which causes the liquid drops to be crushed and its amount increases significantly. In this case, the mechanical energy consumed in the device increases.

In the rotor-filter device, the energy consumption includes the dust gas inlet and outlet of the device, the nozzles, the dust gas cleaning using liquid, the energy spent to rotate the rotor, and due to the friction in the pumps and fans.

Since it is difficult to calculate the exact amount of energy spent on the fluid flow in the device, the rotation of the rotor, and the friction of the dusty gas flow as it passes through the device, we use the research work of K.T.Semrau to calculate the total energy consumption approximately according to the following equation. This calculation method gives an error of ±10% when applied to wet dusty gas purification devices with different designs and operating principles. The total energy consumption of a rotor-filter device is determined by the following equation, kJ/1000m³ [10];

                                                    (2)

where ΔP_s is the hydraulic resistance of the device without liquid, Pa; ΔP_hr is the hydraulic resistance of the device with liquid, which depends on the density of the dust entering with the gas, Pa; V_l is the volumetric flow rate of the liquid, m³; V_gas is the volumetric flow rate of the gas with dust, m³; N_PCR is the power consumed to rotate the rotor, transfer liquid and gas, W;

Based on the above, the energy consumed for dusty gas purification was determined experimentally and compared with the results of theoretical calculations. The experimental results are presented in Figure 7.

1-when plain water is used as the working fluid; 2-when Na₂CO₃ is added to the water composition in a mass fraction of 10; 15 and 20%

Figure 7. Dependence of consumed energy on gas velocity

The graphical relationship in Figure 7 shows that when comparing the mechanical energy consumption with the energy spent on overcoming hydraulic resistance, its amount decreases from 20% to 7% of the total energy. H₂O and Na₂CO₃ When using a mixture of water and air, the previous dependence of the parameters is observed, but the energy consumption increases by 1.25-1.89 times compared to water.

Conclusion. In the case of a rotor filter self-supplied with liquid from a liquid bath, an increase in mechanical energy consumption is observed during dust capture. An increase in the physicochemical properties of the sediment leads to an increase in energy consumption. The greatest energy consumption is observed when capturing dust that has a high viscosity when mixed with water. Therefore, choosing a liquid that matches the physicochemical properties of the dust during dust collection can somewhat reduce energy consumption.

References:

1. Abdurakhmon, S., Azizbek, I., & Mahfuza, Z. (2022). Hydrodynamics of a galvanized plate scrubber. Universum: texnicheskie nаuki, (11-7 (104)), 10-16.
2. Mаdаminovа, G. I., Kаrimov, I. T., & Isomidinov, А. S. (2022). АNАLIZ DISPERSNOGO SOSTАVА OBRАZЦOV PЫLEVЫX ChАSTIЦ.
3. Kаrimov, I. T., Isomidinov, А. S., Mаdаminovа, G. I., Xomidov, X. R., & Mаxmudov, А. А. (2022). Sistemnыy аnаliz intensifikацii proцessov v kojuxotrubchаtыx teploobmennыx аppаrаtаx.
4. Uktamovich, S. R., Akhmadjonovich, E. N., Salomidinovich, I. A., & Bektoshevich, U. R. (2022). RESEARCH OF RESISTANCES AFFECTING THE WORKING FLUID IN A ROTOR-FILTER DEVICE. Innovative Technologica: Methodical Research Journal, 3(11), 8-15.
5. Rasuljon, T., Isomiddinov, A., Ortiqaliyev, B., & Khursanov, B. Z. (2022). Influence of previous mechanical treatments on material grinding. International Journal of Advance Scientific Research, 2(11), 35-43.
6. Akhmadjonovich, E. N., Salomidinovich, I. A., Uktamovich, S. R., & Bektoshevich, U. R. (2022). LIQUID GASES TRANSMISSION MEDIUM TOZALOVCHI INERTIAL HYDRODYNAMIC SCRUBBER. American Journal of Business Management, Economics and Banking, 7, 1-7.
7. Akhmadjonovich, E. N., Salomidinovich, I. A., & Bektoshevich, U. R. (2022). INTENSIFICATION OF DUST GAS CLEANING PROCESS. American Journal of Technology and Applied Sciences, 7, 67-71.
8. Akhmadjonovich, E. N., Salomidinovich, I. A., & Аliyorovich, O. X. (2022). EXPERIMENTAL DETERMINATION OF THE INDUSTRIAL APPLICATION AND DETERMINATION EFFICIENCY OF FLUID GASES CLEANING APPARATUS BY CONTACT ELEMENT METHOD. American Journal of Technology and Applied Sciences, 7, 72-78.