DS Akjoltai Smoke removal

Contents

Task

Introduction

1 Study of dust properties of grain processing plants

2 Ventilation Network Layout

2.1 Study of layout principles

2.2 Drawing Up Network Layout Table

2.3 Analysis of layout proposed for development of network from the position of layout principles

3 Selection of dust separator to the network

3.1 Selection of cyclone to the network

3.2 Selection of cyclone filter to the network

3.3 Analysis of technical and economic parameters of the dust separator and final selection of the dust separator to the network

4 Pre-fitting the fan to the mains

5 Study of equipment to be aspirated in the developed network

6 Development of local resistance characteristics

7 Determination of dimensions and characteristics of suction pipes to aspirated machines

8 Development of the design plane diagram of the network route

9 Design of design plane diagram of the network

10 Calculation of ventilation network

11 Final selection of fan to the network. Calculation of power per fan drive. Select Fan Drive

12 Development of planar network wiring diagram

13 Conclusion

14 List of literature

Introduction

The air in any production room is constantly contaminated by various gases and water vapours emitted during production. The most harmful component entering the air at grain processing plants is dust of organic and mineral origin. Since all transport and processing operations of grain storage and processing are accompanied by significant dust discharges, ventilation plants are called upon in the course of their work to create and maintain sanitary and hygienic standards that meet the requirements of SNiP.

During ventilation, air contaminated with impurities is removed and supplied instead of pure air. In order to have air exchange, it is necessary to organize a directional movement of air masses.

Depending on how the air flow moves, ventilation is generally divided into natural and artificial (mechanical). Natural ventilation occurs as a result of the difference in temperature and pressure outside and inside the building, that is, it occurs under the influence of gravitational forces, as well as due to the effect of wind force. Mechanical ventilation occurs as a result of the operation of special machines - fans. The types of ventilation devices should also be distinguished:

- General ventilation, which shall ensure normal sanitary and hygienic conditions in the whole room;

- local ventilation, which creates normal conditions at individual workplaces, preventing the distribution of harm throughout the premises;

- exhaust ventilation, it is necessary to remove contaminated air;

- plenum ventilation, by means of which clean air is forced into the room.

The grain processing industry has a special type of ventilation plant called aspiration plants.

The process taking place in these plants is called aspiration.

Aspiration is the process of creating a reduced pressure in the working spaces of machines by sucking a certain volume of air from them. The resulting discharge in the machine localizes the dust, preventing the dusty air from entering the room. Air sucked from the machine carries away a significant amount of dust, as well as excess heat and moisture generated during the processing of grain into flour and cereal.

Ventilation plants at grain processing plants are an integral part of the process. The total cost of operating aspiration networks is 12... 15% of all the energy costs of the enterprise as a whole.

Ventilation plants at grain processing plants allow you to:

- Improve and improve working conditions, eliminate occupational diseases of workers;

- Create the necessary hygienic prerequisites for increasing productivity;

- increase the productivity of mills, cereals and feed mills due to maintaining the normal process, which is caused in particular by increasing the intensity of sieves, etc.;

- improve the quality of flour;

- it is better to clean grains and grinding products;

- prevent self-heating of grain, reduce humidity;

- prevent the development of pests;

- reduce grain losses resulting from its processing into flour and cereal due to the reduction of the number of sweeps and dispersion of dust products;

- improve the sanitary and hygienic condition of enterprises as a result of preventing the possibility of condensation of moisture on the internal surfaces of machines, the formation of dough crusts, the development of microorganisms, as well as

grain lei and its processing products inside aspirable equipment;

- protect bearings from premature wear caused by permanent abrasive action of mineral dust;

- prevent the possibility of dust explosions and fires.

1 Study of dust properties of grain processing plants

At grain processing enterprises, all processes related to the processing of grain material and its transportation are accompanied by the release of a huge amount of dust. Especially a lot of dust is released from impact machines (hammer crushers, soiled machines, etc.), in such machines explosive concentrations of dust can occur, eliminated only with reliable aspiration operation. Dust air is a dispersed system including a gaseous medium and a solid dispersed phase distributed in it, that is, dust.

Dust is called finely divided particles of solid substance, which can be carried away by a moving stream of air. Dust in the air can be in two states:

1) aerosol (suspended);

2) aerogel (settled).

The composition of dust is determined by its origin:

I By origin, dust is divided into:

1 - organic;

2 - mineral;

3 - mixed.

Dust of grain processing enterprises is most often a mixture of dust of organic and mineral origin, while dust on elevators and grain deposits contains more than 50% of mineral particles. Dust of preparatory sections of mills and cereals plants contains from 8095% of organic dust. All flour dust (in milled, knocked-out, warehouses) is carried from to organic dust.

II In terms of value, the following dust is distributed at grain processing plants:

1 - unsuitable, black dust with ash content more than 6.5% (to be destroyed);

2 - gray, fodder dust with ash content of 2.0-6.5% is used in feed processing;

3 - food, white dust with ash content up to 2.0% (added to flour of the 2nd grade).

III By dispersion composition.

Dust is extremely inhomogeneous and is divided into three cathegos-rii in particle size:

1 - large dust (from 50 to 250 μm);

2 - medium, dispersed (from 10 to 50 microns);

3 - fine, finely dispersed (less than 10 μm).

Large dust prevails on grain elevators and warehouses; in the preparatory departments of mills and cereals - medium-dispersed; in grinding, knockout and feed compartments - fine dust.

Sanitary rules and regulations (SanPiN) establish requirements for dust content of air in the working area of the industrial premises.

Air dust content in the atmosphere shall not exceed 0.5 mg/m3.

Dust, which is in the air in aerosol, that is, in a suspended state, forms explosive mixtures, which at certain concentrations of dust and in the presence of an energy source can explode.

Dust explosion is a process of instantaneous combustion, when oxygen of the spirit is connected to a large surface of combustible material, such an explosion leads to the formation of a huge amount of gaseous substances and an increase in air pressure (5... 7) Pa.

From the point of view of explosion-proof operation of process equipment, it is very important to prevent explosive concentration of dust inside the machine body.

As the most active measure to combat explosions at grain processing enterprises, it is competent design, reliable high-efficiency operation of aspiration networks.

In order to ensure explosion safety, the following measures shall be taken at grain processing plants:

1) ensure reliable and efficient operation of all aspiration networks;

2) ensure high-efficiency operation of stone assembly machines;

3) combat static electricity;

4) use explosion-proof electrical equipment and dust-impermeable lighting fixtures;

5) prevention of sparking;

6) observance of safety precautions during fire works and storage of flammable liquids;

7) use of explosion protection systems:

- explosion dischargers;

- pressure sensors;

- speed control relay;

- flame breakers, etc.

8) Exclude the possibility of rubble, product subsectors, dust, fuel and lubricant leaks from reduction gears during equipment operation.

5 Study of equipment to be aspirated in the developed network

Noria is used as lifting and transportation equipment for transporting grain and other fine dry materials in the vertical direction. The transported material is delivered through the loading spout to the ladles or is selected by the ladles from the bottom of the shoe and moved by the transported element to the upper head, where the ladles are unloaded to the unloading branch pipe. Noria shoe aspiration is performed through hole located perpendicular to vertical channel.

Peeling machine of grade P3BMO6 is used in grain cleaning sections of mills for dry cleaning of grain surface from dust, partial separation of antennae, beard and grain embryo. Vertical gear machine is aspirated through lower outlet device located in front of lock gate.

Trier is designed for separation of mixtures along the length. In elevators, chalk and cereals, triers are used to extract oatmeal and pupa seeds from grain mixtures; in cereals, in addition, to separate oats from barley and separate, peeled and not peeled grains; at seed processing plants and at plants for calibrating corn seeds, they (triers) are installed to extract the largest grains from the mixture.

Disk triers A9-UTO-6 and A9-UTK-6 are designed: the first - for the isolation of long impurities (mainly oatmeal) from mixtures, and the second - short impurities (mainly pupa). Trier aspiration is performed through branch pipe located in upper part of machine. The who-spirit is sucked from the machine vertically up.

12 Development of planar network wiring diagram

Based on the results of the calculation, a flat wiring diagram is drawn on a separate sheet without scale and a detailed graphical specification of the parts is compiled.

The wiring diagrams show all parts of the ducts: straights, confusers, taps, tees, diffusers, etc. The diameters of the ducts are drawn based on the results of the network calculation. Fans and dust collectors on wiring diagrams can be drawn without a detailed image, i.e. schematically. Flange joints and transverse folds are drawn with main lines, and longitudinal folds of air ducts are not drawn.

Installation diagrams indicate places of holes with plugs and nozzles for aerometric measurements. These openings in the air ducts are provided after each aspirable point, before and after the dust collector, before and after the fan. Places of holes for measurements are selected on straight sections of air ducts with aligned air flows. Measuring sections in accordance with GOST 12.3.01879 "Ventilation systems. Aerodynamic test methods "are selected at a distance of at least 6 diameters D, behind the point of flow disturbance and at least two diameters in front of it. In the absence of rectilinear sections of the required length, it is permitted to place the measured section at a location dividing the selected section in a ratio of 3:1 in the direction of air movement. The holes for measurements with plugs indicate the wiring diagrams with the assignment of one number and its inclusion in the specification .

The planar wiring diagram is the basis for the manufacture and installation of parts and the entire ventilation network in kind. Therefore, the thoroughness of its implementation should be given the most serious attention.

13 Conclusion

As part of this course work, a ventilation network was calculated for aspiration of the technological equipment of the preparatory mill from-division, namely:

No. 1 - shoe of I20 - 1 pcs ;

No. 2 - R3BMO6 test machine;

No. 3 - trier A9UTK6;

No. 4 - trier A9UTO6.

The ventilation network has a total length on the suction line of 24.4 m and a pressure loss along the main direction of the network Nmag = 1656.7 Pa.

The network includes the following ventilation equipment:

1) centrifugal fan of V.Ts5354V1.01 brand with the following operation parameters in network:

- the volume of the air moved with the fan in Qv network = 2152 m3/h ;

- pressure developed by fan Hv = 1855 Pa;

- speed of impeller nfan = 2930 rpm;

- efficiency ηв = 0.688;

- fan impeller is driven through V-belt transmission from shaft of AIM80V2 electric motor with power No = 2.2 kW and speed ne = 2930 rpm

2) dust separator - filter-cyclone of RTSE grade 6.916 with resistance Np/o = 814.9 Pa.

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