The Republic of Uzbekistan is a world leader in cotton production and processing and export. Therefore, cotton fiber and its processing play an important role in the country's economy

§ 1.4 Analysis of research on inertial separators for inertial separation of raw cotton.

In the pneumatic transport system, the process of separating the raw cotton from the mesh surface using a scraper causes problems such as fiber defects and consequent reduction of fiber content, as well as damage to the cotton seed. effective separation methods and device designs have been proposed. Separators of this type can be conditionally divided into types based on gravity, inertia and centrifugal force.

Separator - separation part: consists of a mesh surface and a nozzle, the discharge part: a vacuum valve, a cylindrical wall (surface) and a wing drum.

The main technological indicator of separators is their aerodynamic drag coefficient.

The pneumoseparation process is mainly affected by two forces on the product pieces in a vertical air flow: The first is the dynamic pressure and the aerodynamic lifting force proportional to the cross-sectional area of ​​the piece;

The second is the downward gravitational force equal to the mass of the cotton piece.

The possibility of separating raw cotton using centrifugal force using curved air ducts was theoretically substantiated by the academician of the Academy of Sciences of Uzbekistan HA Rakhmatulin [41]. He determined the law of motion of cotton in conductors installed in the airway, taking into account the aerodynamic resistance of the air.

The results of his calculations showed that the aerodynamic drag forces were less noticeable for the cotton piece. The trajectory of the cotton swab will be in a straight line in the direction of the air duct as it descends into the inlet chamber. This results in a process of material separation.

Studies based on the opinion of H.A. Rakhmatulin show that it is possible to use an inertial separator operating under the influence of centrifugal force of the pneumatic transport system (Figure 1.10) [41].

Continuing Rakhmatulin's idea, GB Bakhriev showed that the flow rate at the time of arrival at the separator depends not only on the size and initial velocity of the components, but also on the coefficient "k" and the concentration of the separated substance [42].

Figure 1.10. Inertial separator

1 inlet pipe; 2 turning channel; Separation zone 3; 4-vacuum bunker; 5 vacuum-valve blades; 6 outlet pipe.

The spiral plate is connected to the separation chamber through an air outlet duct. The return barrier is mounted under the air outlet duct with a wall on the side of the separation chamber (Figure 1.11).

Figure 1.11. Spiral plate pneumoseparator.

1 inlet pipe; 2 air outlet ducts; 3-spiral plate; Set 4; 5-vacuum-valve; 6 outlet pipe; 7 separation chamber.

The spiral plate is connected to the lower wall of the inlet pipe and to the upper wall of the barrier. When the separator is running, the cotton is passed through the inlet pipe along with the air flow. Due to the centrifugal force and the weight of the cotton, it separates from the air and goes down to the vacuum valve. The air is transferred to the spiral tube through the exhaust duct. When some pieces of cotton move under the influence of air flow towards the exhaust duct, they hit the barrier and are returned and transferred to the vacuum valve, and then removed from the chamber.

The main disadvantage of this pneumo-separator is that as a result of the accumulation of cotton under the inlet pipe, the cotton separated by air inertia, centrifugal and gravity forces is absorbed by the vacuum-valve circulation and begins to rise towards the pneumo-separator chamber. This leads to breakage of cotton seeds and deterioration of fiber quality under the influence of fan blades. In addition, in some cases it is likely that the raw cotton will sit on a spiral bent plate as the velocity in the inlet pipe is slightly reduced. As a result, the cotton inlet pipe becomes clogged. In addition, the cotton wool collected on the plate may be exposed to air and some of the cotton pieces may be removed. In order to correct these shortcomings, an improved version of the pneumatic separator was created.

Another invention is an additional air duct pneumoseparator created and improved by R.Muradov, which is connected to the outlet pipe in the form of holes with an inlet pipe mounted at an angle of 20 - 25 ° to the horizontal plane (Figure 1.12).

Figure 1.12. Additional channel pneumoseparator

1 inlet pipe; Output channel 2; 3-spiral plate; 4 air suction pipe; 5 return set; 6 additional air ducts; 7-vacuum-valve; 8 discharge pipe; 9 separation chamber; 10-slope wall; 11 reference set.

When the pneumatic separator is running, the cotton is passed through the inlet pipe along with the air flow. The cotton moves correctly under the influence of the force of inertia and hits the wall of the separation chamber. It then falls into the vacuum-valve through the separation chamber under the influence of its own weight and centrifugal force. The air moves along the exhaust duct and is sent to the cyclone through a suction tube using a spiral plate [43].

The author also created a pneumatic separator of a different design, which also separates the raw cotton transported in the air stream under the influence of inertial forces (Figure 1.13).

Figure 1.13. Pneumoparator

1 oblique pipeline; 2 receiver short tube; Set 3; 4 return;

5 air permeable; 6 output short pipe; 7 throttling device;

8 outlet pipe; 9 separation chamber; 10-vacuum-valve.

In a pneumose separator, cotton is thus separated from the carrier air stream. Vacuum - As a result of valve rotation, air is sucked into the separation chamber inside this section as its sections are emptied of cotton. To ensure that this air does not affect the cotton separation process, it is reduced by the addition of air to the cotton pieces when the inlet pneumoparator is operated through an additional air tube and holes. The inclined installation of the inlet pipe at an angle of 20-25 ° to the horizontal and the installation of a curved barrier in the separation chamber eliminates the penetration of the pneumatic separator into the inlet pipe and improves the process of separating the cotton from the air flow.

The scientific basis for the process of air transportation of cotton was laid in 1929. In the same year, for the first time, the equation for the relationship between the absorption rate of cotton and the air flow rate was developed:

(1)

where: - air velocity, m / s; - speed of cotton, m / s.

S. Kadyrkhodjaev [44] found changes in the speed of movement of cotton pieces at different weights. Basically:

a) The speed of movement of cotton is related to the speed of air in pieces of different weights and sizes as follows:

(2)

b) The relationship between the minimum air velocity and the air-carrying capacity of the air-carrying device is calculated as follows:

(3)

where: - productivity of air transportation of cotton, t / h.

c) To determine the rate of absorption of cotton, the following expression is proposed:

(4)

where: -density of cotton, kg / m3; -diameter of a piece of cotton, m; - air density, kg / m3.

T.D. In a study by Makhametov [45], the position of a piece of cotton moving in the air was studied by means of an accelerated video image. The author found that the flat distribution of a piece of cotton in a horizontal pipe on its cutting surface depends on the air velocity. There can be three different movements depending on the speed of the air.

a) progress,

b) jumping,

c) twisted.

The ratio of the velocities of motion of cotton and air was determined experimentally. These indicators are as follows:

For individual parts:

(5)

For airlines:

(6)

In the work of S.Kh. Kadyrkhodjaev [44], H. Akhmedkhodjaev [46] and others, the process of transporting cotton by air was studied in detail.

Studies have shown that the material rotates around its axis as it moves forward in a horizontal tube, in which the speed of movement of the material depends on the speed of the air flow:

m / s (7)

Where: Vm is the velocity of the material;

Ux is the speed of air.

Based on the above research work, we have seen the possibility of carrying out the process of separating cotton from the air stream without the use of a mesh surface and a scraper. However, in the implementation of the separation process in such devices, the aerodynamic resistance of the air to the specified norm played a very important role. In improving the design of the separator, first of all, it is necessary to take into account the improvement of the working parts and their elements, the development of new tools to replace them.

Improving the design of the separator by releasing the separating part of the separator from the mechanically moving elements, using the effect of centrifugal forces;

Simplify the separator design and improve the work process by combining the separation and discharge parts and assigning the functions they perform to one work piece;

Improving work process performance and product quality by improving mesh surface constructions; Improving work process performance and product quality by improving the vacuum-valve elements cylindrical surface and vane drum designs.