ENERGY CONSUMPTION IN A SIEVE PLATE SCRUBBER

ABSTRACT

The research paper presents the results of the theoretical and practical work carried out on the effect of the main characteristics on the energy loss of the selection of the optimal values of the loads affecting the dust gas flow moving in the wet dust gas scrubber on the working bodies of the device. The energy loss in the apparatus is determined for different values of the variable factors.

АННОТАЦИЯ

В работе представлены результаты теоретических и практических работ по изучению влияния основных характеристик на потери энергии при выборе оптимальных значений нагрузок, действующих на пылегазовый поток, движущийся в мокром пылегазовом скруббере, на рабочую корпуса устройства. Потери энергии в аппарате определяются при различных значениях переменных факторов.

Keywords: energy, hydraulic resistance, volumetric gas and liquid consumption, resistance coefficient, liquid and gas velocity, hypothesis.

Ключевые слова: энергия, гидравлическое сопротивление, объемный расход газа и жидкости, коэффициент сопротивления, скорость жидкости и газа, гипотеза.

Introduction

It is known from the conducted experiments that the efficiency of mechanical and dynamic dust cleaning devices working in the wet method is primarily determined by the energy used to implement the process [1,2,7,8].

As a result of the research of wet dust cleaning devices of various constructions, it was found that the efficiency of capturing dust particles in a certain gas depends only on the pressure loss in the device, and does not depend on the size and design of the device. In this case, the total energy consumption should be spent on coagulation (contact time and absorption of the particle into the liquid environment) between the liquid and the dust particle. This hypothesis is presented in the research work of Semrau KT, according to which, as a result of the interaction of dusty gas and liquid, energy is spent to form a turbulizing flow of the gas-liquid mixture, and then the spent energy is converted into heat [2,4,5,7]. Therefore, the energy spent to process a certain amount of dust gas volume at one time is called the energy parameter of dust collectors.

Contact energy between liquid and gas generally consists of three types of energy:

• gas flow energy, that is, characterizes the degree of turbulization of the gas-liquid flow in the apparatus.
• liquid flow energy characterizing liquid dispersion;
• mechanical energy generated in the rotating structural elements of dynamic gas washers (scrubbers).
• contact energy is less than the total energy in wet dust collectors. Also, this energy does not include the energy spent on the gas inlet and outlet of the device, nozzles, liquid coagulation of dust particles, and friction in pumps and fans.

If the wet vacuum cleaner is equipped with a fan or a liquid pump at the same time, then the energy that creates the flow movement is not included in the energy created in the interaction between the liquid and the gas. Given this, it is difficult to calculate the exact value of the impact energy.

Usually, the hydraulic resistance of the apparatus ΔР_an (Pa) is taken as the energy of the gas flow. This energy should have a small value in dry-type equipment [3,6,9,10].

The useful energy of high-speed wet vacuum cleaners is significantly greater than the energy lost due to friction in the absence of fluid. In the device working at low pressure (speed), this situation depends on several parameters of useful energy.

Theoretical studies

In the research work of K.T.Semrau, an approximate calculation of the total energy consumption was included according to the following equation, kJ/1000m³ [2,4,7];

                                                                         (1)

where ΔP_liq is the hydraulic resistance of the device without liquid supply, Pa; ΔP_liq is the hydraulic resistance of the device with a given liquid, which depends on the density of dust entering with the gas, Pa; V_liq - volume consumption of liquid, m³; V_gas - volume consumption of dusty gas, m3; N_SKP - power used for liquid and gas transfer, W;

This method of calculation gives an error of ±10% when applied to wet scrubbers of different constructions and operating principles. K_SKR each of the quantities included in the determination depends on the type of hardware. For example, the hydraulic resistance of the device in the venturi scrubber, the time of coagulation between the liquid and the dust particle and the pressure exerted on it are of decisive importance in the nozzle succubers. Therefore, it is appropriate to use equation (1) only in the calculation of dynamic dust cleaning devices.

In the case of wet dust gas cleaning mechanical devices, in equation (1). N_SKP/V_gas value can be ignored. In that case equation (1) can be written as; kJ/1000m³ [2,4,7];

                                                                          (2)

Thus, the energy calculation is divided into three main categories according to the energy supplied to the device working in a loose method:

• dust cleaning devices that create gas flow energy;
• dust cleaning devices using liquid flow energy;
• mechanical energy-powered dust cleaning devices.

If we take into account that the recommended spherical plate scrubber belongs to the category of mechanical dust cleaning devices, it is appropriate to determine its energy consumption using the given equation (2).

Research results

The following limits of the variable factors in the scrubber with a plate-shaped plate, the diameter of the liquid nozzle d_sh=3 mm, the liquid consumption Q_liq=0.071÷0.189 m³/hour, the intermediate step 0.021 m³/hour, the diameter of the plate-shaped filter hole d_f=2, 3 and 4 mm, the plate filter to the device installation angle β = 15^o; The number of 30^o and 45^o plates is 2 pieces, according to the angle of installation, gas velocity υ_g=7.4÷28.8 m/s, the intermediate step is 5.5 m/s on average, and the effect of variable factors on the hydraulic resistance in the apparatus was studied. In the experiments, the gas density for the mixture of air and dust of superphosphate mineral fertilizer was determined as ρ_g=3.38 kg/m³ (the amount of the mixture of gas and dust is 1906.5÷2697.79 mgr in 1 m³ of air).

This research work focused on investigating the effect of hydraulic resistance on energy consumption. Taking into account that the conducted theoretical calculations are multi-level, the energy consumption for the lower and higher loads of the hydraulic resistance was determined and the change points in the intermediate values were analyzed. The results of the general experiment to determine energy consumption are presented in Figure 1.

Figure 1. Graph of change of energy consumption at a minimum and maximum values of hydraulic resistance

1- ρ =3.38 kg/m³ and d_f=4mm; 2- ρ =3.38 kg/m³ and d_f=3mm; 3- ρ =3.38 kg/m³ and d_f=2mm;

a-When the angle of installation of the plate to the apparatus is φ = 15° and the velocity of dust gas is 7.4 m/s; b-When the angle of installation of the plate to the apparatus is φ = 15° and the speed of dust gas is 28.8 m/s; c - When the angle of installation of the plate to the apparatus is φ = 30° and the velocity of dust gas is 7.4 m/s; g-When the angle of installation of the plate to the apparatus is φ = 30° and the velocity of dust gas is 28.8 m/s; d-When the angle of installation of the plate to the apparatus is φ = 45° and the velocity of dust gas is 7.4 m/s; e-When the angle of installation of the plate to the apparatus is φ = 45° and the speed of dust gas is 28.8 m/s;

1 a, b, v, g, d and e, it can be seen from the data given in the pictures that the speed of the dust gas supplied to the device, the working details of the device (spherical plate, spreading plate and the work, in turn, increase the energy consumption lost in the device. For example, the angle of installation of the plate to the device is φ = 45° and the diameter of the plate hole d_f If the minimum energy loss d_f =4mm is 42 J, the mounting angle of the plate to the apparatus is φ = 15° and the diameter of the plate hole d_f =2mm, the maximum energy loss was 4128 J. That is, the increase in resistance in the device causes an increase in hydraulic resistance, which in turn causes an increase in energy consumption.

1 a, b, v, g, d and e-The following empirical formulas were obtained using the method of least squares for the graphic dependences presented in the pictures [11,12,13].

When the angle of installation of the plate to the apparatus is φ = 15° and the velocity of dust gas is 7.4 m/s; 

y = 4E-05x² - 0.0064x + 67.725                  R² = 0,9994                   (3)

y = -0.0006x² + 0.4503x                             R² = 0,6267                   (4)

y = 4E-05x² - 0.0058x + 63.798                  R² = 0,9994                   (5)

When the mounting angle of the plate to the apparatus is φ = 15° and the dust gas velocity is 28.8 m/s

y = 3E-07x² - 0.0016x + 1211.2                  R² = 0.9919                   (6)

y = 1E-07x² - 0.0001x + 1043                     R² = 0,9929                   (7)

y = 1E-07x² - 0.0001x + 988.09                  R² = 0.9931                   (8)

When the mounting angle of the plate to the apparatus is φ = 30° and the dust gas velocity is 7.4 m/s

y = 7E-05x² - 0.0087x + 49.277                  R² = 0.9994                   (9)

y = -0.0002x² + 0.1019x + 43.328               R² = 0.9906                   (10)

y = 7E-05x² - 0.0079x + 46.415                  R² = 0.9994                   (11)

When the mounting angle of the plate to the apparatus is φ = 30° and the dust gas velocity is 28.8 m/s

y = 2E-07x² + 8E-05x + 881                       R² = 0,9974                   (12)

y = 2E-07x² - 0.0002x + 761.33                  R² = 0.9942                   (13)

y = 2E-07x² - 0.0002x + 721.27                  R² = 0.9944                   (14)

When the mounting angle of the plate to the apparatus is φ = 45° and the dust gas velocity is 7.4 m/s.

y = 7E-05x² - 0.0087x + 43.85                    R² = 0.9993                   (15)

y = -0.0002x² + 0.0996x + 37.423               R² = 0,9907                   (16)

y = 9E-05x² - 0.0088x + 41.112                  R² = 0,9993                   (17)

When the angle of installation of the plate to the apparatus is φ = 45° and the speed of dust gas is 28.8 m/s;

y = -3E-07x² + 0.0034x + 780.9                  R² = 0.9865                   (18)

y = 2E-07x² - 0.0002x + 679.08                  R² = 0.9946                   (19)

y = 2E-07x²- 0.0002x + 643.14                   R² = 0.9948                   (20)

Conclusion

• as a result of the research of wet dust cleaning devices of various constructions, it was found that the efficiency of capturing dust particles in a certain gas depends only on the pressure loss in the device, and does not depend on the size and design of the device;
• the energy consumption lost in the apparatus was determined in different dimensions of the diameter of the hole of the spherical plate and the angle of its installation to the apparatus body.

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