Division of Ground Grain in Pneumo-Screw Stream

Division of Ground Grain in

Pneumo-Screw Stream

Object of Research

Process of division of ground grain in a pneumo-screw stream and means for its realization are considered as object of researches.

Research purpose - increase of separation efficiency and increase in quantity of received fractions of ground grain in a pneumo-screw stream and working out of the scientific positions defining creation of technical devices for centrifugal separation

Research problems:

to develop mathematical model of process of division of ground grain in a pneumo-screw stream, to prove a choice of parameters.

to develop the technical device, allowing to carry out process of division of ground grain in a pneumo-screw stream.

to define experimentally optimum parameters of division in a pneumo-screw stream, to compare them to the data received by mathematical modelling.

On most farms small shops and aggregates are used to make flour, that’s why they’re limited in the equipment and as a result they’ve got low productivity.

In a flour milling procedure one of the main processes is dividing of ground grain. So finally we’ve got ground grain of different size and it should be devised and sent to various technological processes.

In a complicated process on a modern mill the pneumatic transport is widespread. A centrifugal cyclone divisor is one of the units in the pneumatic transport used in  flour milling.

During the literary review and patent search some designs in which the screw surface is used and also other devices of cyclonic type for sorting a powder product were revealed. Besides the way of aeromechanical division of grain materials is found out by creation of an aero mix and influence on it pulse air stream. That grants the right to a life to our hypothesis about division of ground grain in pneumo-screw channel formed by two  screw at influence on a mix of a material with air radial currents carrying away valuable fine fraction.

On the basis of the considered designs there was an idea to create  the pneumatic screw  classifier shown in Figure 12. The pneumatic screw classifier consists of components as follows: 1 - an axial branch pipe; 2 - a top with a branch pipe for discharge medium fraction; 3 - a loading branch pipe; 4 - a directing screw  ; 5 - a working screw ; 6 - openings; 7 - a cone.

The given device will allow to carry out preliminary division of particles on size, on specific density and aerodynamic properties. That will lead to decrease in specific loading and to increase  using efficiency  of a sifting surface of Plan Sifter.

MATERIALS AND METHODS

The Test-plant

The test plant shown in Figure 13 is composed of: blower, cyclone dust collectors, pneumatic screw  classifier, frame, hopper, and system of pipelines. The ground grains in each cyclone were collected manually separately for analysis.

Principle of Operation

The ground grain  with air moves through a tangential loading branch pipe 3 under the influence of gravity and aerodynamic forces makes difficult curvilinear movement on working screw 5. Bleed of air through openings 6 and the branch pipe 1 leads to occurrence in gas of a radial current which carries away fine fraction which is taken away through a branch pipe 1. The coarse fraction moves to periphery, is precipitate on an internal surface of the case, loses speed, fall out of an air stream and through a ring gap flows down in a cone 7. Medium particles carried away  by an air stream and are taken out from the device, through a branch pipe of a top 2.

CONCLUSIONS

From the investigation of grain separation the following results were obtained:

1.  Grain separation along the screw can be divided into two sections: accelerating and separating.

2.  Separating efficiency decreased with increasing air speed.

3.  There was a decreasing in separating efficiency with increasing feed rate.

4. Separating efficiency decreased with increasing screw length at different air speeds.

Combining some technological operations in one machine increases its effectiveness.

So, the researchers in the field of material division on to fractions under the pneumatic centrifugal forces are acute and necessary for solving technological problems.

My research work “Division of ground grain in a pneumо-screw stream” is lead by a well-known expert in the field of grain processing. The results of my work will be published in some reports. So I hope I’ll be able to gain my goal and get a candidate’s degree.