CC BY
3УДК 942.622
HYDRODYNAMICS OF A SCRUBBER FOR WET CLEANING OF POWDER GAS
GENERATIONS
Tojiyev Rasuljon Jumabayevich Professor of Ferghana Polytechnic Institute, E-mail: [email protected], Rasuljon [email protected]
Sulaymonov Abdurahmon Maxamadovich Doctoral student, Fergana Polytechnic Institute, E-mail: [email protected], [email protected]
Abstract: The article presents a theoretical research work on the determination of the coefficient of resistance and resistance of gravity in the working bodies of industrial secondary casting gases washing scrubber. An equation was drawn up that determined the total mass resistance of the scrubber, and equations that determined the mass resistance and the coefficient of resistance of each working body were recommended.
Аннотация: В статье представлены теоретические исследования по определению гидравлического сопротивления и коэффициента сопротивления рабочих органов скрубберов промышленных вторичных отработавших газов. Построено уравнение для определения полного гидравлического сопротивления скруббера и предложены уравнения для определения гидравлического сопротивления и коэффициента сопротивления каждого рабочего органа.
Аннотация: Маколада саноат иккиламчи ташлама газларини ювиб тозаловчи скруббер ишчи органларидаги гидравлик каршиликлар ва каршилик коэффициентини аниклаш буйича олиб борилган назарий тадкикот ишлари келтирилган. Скруббернинг умумий гидравлик каршилигини аникловчи тенглама тузилган ва х,ар бир ишчи органнинг гидравлик каршилиги ва каршилик коэффициентини аникловчи тенгламалар тавсия этилган.
Key words: hydraulic resistance, reference pipe, conical plug, lattice nozzles, resistance coefficient, throttle valve, gas flow force.
Ключевые слова: гидравлическое сопротивление, направляющая труба, конусная заглушка, решетчатое сопло, коэффициент сопротивления, выхлопной газ, сила газового потока.
Таянч сузлар: гидравлик каршилик, йуналтирувчи кувур, конуссимон тикин, панжарали насадка, каршилик коэффиценти, ташлама газ, газ окимининг кучи
Introduction:
Dust and gas cleaning equipment is characterized by the principle of operation and design of the device and is widely used in industry
It should be noted that the literature does not provide a clear classification of dust collecting devices, but it is possible to study the design and operation of dust collecting devices in general, which have already been developed and proposed in scientific research. In general, when evaluating the variety of dust and gas cleaning devices, it is possible to conditionally and generally use devices of any design. Methods for cleaning dusty gases are shown in Figure 1.
Among the considered dust and gas cleaning devices, wet cleaning devices are distinguished by high efficiency. These types of devices are also made in accordance with the basic law of dust gas purification. Therefore, a specific trend in the use of this type of device is
currently being developed, as well as through scientific research, effective applications are found in industry.
Figure 1. Methods for cleaning dust gases.
Literature review:
Designs of wet dust and gas cleaning devices vary, and the most common of these devices are scrubbers. The main advantage of scrubbers over other wet process devices is that waste water is retained in the pipes of the device, and the sludge generated during cleaning is less likely to stick to the walls of the device. It is also highly effective in the treatment of
corrosive gases with high temperatures and high flow rates [2].
This method also has its disadvantages, for example, the energy costs for cleaning are higher than in the dry method, in which the dust and gases absorbed in the liquid medium have to be reused. In addition, the efficiency of scrubbers used in industry does not always meet the requirements of current environmental standards for the level of MPC of harmful substances emitted into the atmosphere. This is mainly due to external influences loaded on the device and a high addition of dust and secondary gases to the gas flow.
Therefore, it is necessary to create new effective methods to increase the probability of collisions of dust and secondary gases with liquid drops, to improve the design of the device, or to apply an external energy effect [1].
Scrubbers of various designs are used in industry. Among these types of scrubbers, plate scrubbers are the most common devices in terms of scale of use. Depending on the flow of liquid from one plate to another, plate scrubbers are divided into types with and without a pouring device.
The efficient operation of plates with various pouring devices depends on the mode of hydrodynamic movement. Depending on the velocity of the gases and the distribution of the liquid in the trays, plate scrubbers operate in three different modes: bubbling, foaming and fine-flow hydrodynamic. Although these modes differ from each other depending on the composition of the bubble layer, they determine the size of the contact surface, the amount of hydraulic resistance and height (Fig. 2).
IgAP
11 Di B
IgW
Figure 2. Hydrodynamic regimes of lamellar scrubbers.
AB - dry plate operation mode; A1B1-bubble mode; B1C1-foam mode; C1D1 - thin
current mode.
In trays without tundish, gas and liquid pass through the same hole. As a result of simultaneous bubbling of gas and liquid in the tray, part of the liquid spontaneously flows into the lower tray.
Based on the foregoing, a systematic analysis of some designs of devices currently used and tested in research work, and their operating parameters, was carried out. [3, 4, etc.]. The results of the systematic analysis were processed in the MatLAB program and the advantages and disadvantages of the devices were identified. Using the obtained results, an improved design scheme of the plate scrubber was developed [5]. On fig. 3 shows a drawing of a plate scrubber.
Results of analytical studies:
The scrubber consists of a cone and a pipe for supplying secondary gas and a fan, a liquid injector and a pump, contact plates for liquid and gas, a drop eliminator, a cylindrical vertical
body and a pipe for removing the purified gas to the atmosphere
1 7/ 12
Figure 3. Schematic diagram of a plate scrubber. 1 - rack; 2 - support; 3 - cone; 4,7,10,12 - nozzles (A, B, C, D); 5-glass; 6 - shell; 7-day; 9-drop reflector; 11 diffuser; 13 - nozzle; 14 plates; pins 15.18; holder for 16 drops; 17
mechanical sprayers;
Fitting table
Poz. Name Quantity Ду, mm Ру, mm
А Sludge passer 1 50 0,5
B Pure gas output 1 40 0,5
V Fluid inlet 1 25 0,5
G Saw gas inlet 1 75 0,5
A gas distributor is installed in the guide pipe, which distributes the secondary gas over the
cross section of the cylindrical vertical body. The liquid atomization device is equipped with atomizers (liquid nozzles) at the top (four intermediate degrees of 90 degrees to the nozzle) and is attached to the guide tube with a seal and a clamping ring. The spray holes are arranged parallel to the liquid. The working fluid is supplied to it. The gas to be purified is distributed from the bottom of the device upwards and contacts the liquid on the plates. The main advantage of the device over existing scrubbers is that, firstly, its nozzles are in full contact with the gas to be cleaned due to liquid atomization, and secondly, the installation of the plates in an inclined position provides a curvilinear movement of the gas flow in the liquid. Average. This, in turn, increases the mass transfer coefficient.
When moving in a liquid medium, the gas is cleared of dust particles. The purified gas is released into the atmosphere through a pipe.
However, the operating parameters of scrubber devices, including hydraulic resistance, drag coefficient of the working bodies, methods for calculating the cleaning efficiency have not been studied. Therefore, this work is aimed at substantiating the methods for calculating a lamellar scrubber.
Research methodology:
In devices for the neutralization of secondary exhaust gases, it is important to study the loads that affect the speed of the gas in the working bodies of the device, and correctly calculate the calculation equations.
This condition is the main factor determining the hydraulic resistance of the device, the coefficient of resistance in the working bodies and the optimal performance parameters. The increase in hydraulic resistance in the working bodies of the device has a positive effect on the cleaning efficiency, leading to a decrease in labor productivity. This in turn increases the consumption of energy used for cleaning. The scrubber under study consists of a secondary gas pipeline (11), special plates (14), which increase the contact of the gas being cleaned with the working fluid, and a nozzle (13), which directs the working gas flow, experiences hydraulic resistance when it moves in the pipe, when passing through the gas distributor opening and when movement in a plate environment. The total hydraulic resistance acting on the gas to be purified in the device can be written using the calculation equations given in the literature [1,2] and section A-A of the calculation scheme shown in Figure 4:
The equation that determines the total hydraulic resistance of the device can be constructed as follows, Pa;
APg =APp +APtr +APsf +APgl (1)
where Pp is the pressure loss during the movement of secondary gas in the pipeline, determined by the Darcy-Weisbach equation [1, 6]. In this case, the equation can be written as, Pa;
2
APp =£P ^^ (2)
where Up is the velocity of the secondary gas in the pipeline, m/s; is the coefficient of local resistance of the guide pipe, determined by the following formula:
= ^ (3)
de
where l - pipe length, m; de - equivalent pipe diameter, m; It turned out that the X-Darcy coefficient depends on many factors when expressing its law of change by empirical equations. Based on the design of the experimental setup, the definition of the Darcy coefficient in the equation according to the Blasius law was introduced [6]. In this case, equation (3) looks like
this;
6 =-:
0,3164/
de VRe
If we substitute equation (4) into equation (2), then equation (2) will look like this, Pa;
0,316W
PP = I— P 2de VRe
Ptr — dry tray resistance, determined by the following equation, Pa
(4)
(5)
Shlam
4-Figure. Scrubburny iso blash schemes.
2
ДР -А РпРр (6)
Др TR bTR 2
fp
vo - fictitious gas velocity, m/s; f - plate opening surface, m2; pm - density of the secondary gas-air mixture, kg/m3;
£tr - resistance coefficient of the plate hole, which is determined using the experimental technique of B.A. Alimatov and I.T. Karimov on the change in the resistance coefficient of the pipe hole depending on the ratio of the pipe hole thickness to the hole diameter [7]. In this case, the calculation equation can be written as follows;
Ztr = (7)
d
m
where, S - plate hole thickness, mm; dp - plate hole diameter, mm If we substitute equation (7) into equation (6), then equation (6) will look like this: Pa;
APra = (8)
2 • dp
Pm — the density of the mixture of secondary gas and air, which is determined by the following equation. kg/m3;
Pm = Ps + (Pa 7) (9)
where, ps - secondary gas density, kg/m3; pa - air density, kg/m3; y - the amount of secondary gas in the air, %.
APSF - the resistance formed on the surface of the liquid under the action of the surface tension force, which is determined by the following equation, Pa
APSF = ^ (10)
d e
where, de - equivalent diameter of liquid inlets in the tray, m; o - surface tension force,
N/m;
APGL - resistance t of the plate in the gas-liquid layer is equal to the static pressure of the layer:
APGL=h0-prg (11)
h0 - height of the liquid layer on the plate, m pi - density of a liquid in a container, kg/m3 g - acceleration of gravity, m/s2
where, op - gas velocity in the holes of the plate, m/s;
Substituting equations (5), (8), (10) and (11) into equation (1), we obtain the following,
Pa;
ДРо -Pm
^0,3164-1-vl s-ul Л (4a }
p
2da VRë 2 - dp d.
+
+ ho-P - g (12)
V ^ ^ p y v e J
Using the resulting equation (12), we can determine the total hydraulic resistance in the
device.
Conclusion:
Based on the results of theoretical studies with the help of analytical relationships, hydraulic resistances, friction forces and local resistance coefficients acting on the working bodies of the device to dusty gas and working fluid supplied to the device are determined. An
equation is proposed that determines the hydraulic resistance of the scrubber, as well as the coefficients of resistance of the working elements of the device. It was determined that the minimum value of liquid consumption for cleaning 1 m3 of secondary gas should be at least 0.1 l, and the maximum value should not exceed 0.2 l.
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