Ventilation of the thermal workshop with calculations

Contents

Introduction. Data

1. Thermal Workshop Process Characteristics

2. Design air parameters

2.1. Selection of design external parameters

2.2. Selection of calculated internal parameters of microclimate

3. Thermal balance of the room and balance of hazards

3.1. Heat input to rooms

3.2. Room heat loss

4. Calculation of local exhaust ventilation

5. Calculation of local plenum ventilation

6. Calculation of air exchange (general exchange ventilation)

7. Aerodynamic calculation

List of literature used

Introduction

Ventilation is one of the most important systems for ensuring the normal living conditions of human activity. Microclimate parameters have a huge impact on the thermal well-being of a person and his performance. Therefore, to maintain the microclimate parameters at the level necessary to ensure comfort and vital activity, ventilation of premises where a person carries out his/her activities is used. Optimal microclimate parameters are provided by air conditioning systems, and permissible parameters are provided by conventional ventilation and heating systems. Freshness and cleanliness, temperature and humidity in the room are provided by air conditioning and ventilation systems. Human activity and the operation of technical devices are accompanied by the release of heat, harmful gases, vapors, dust, which over time worsen the state of air in the room. Common harmful emissions for residential buildings are heat and moisture, carbon dioxide. The list of harmful substances released into the air of industrial buildings consists of hundreds of items that depend on the purpose of the industrial building. Among them are aerosols, carcinogenic substances, vapors, gases, etc. Freshness and cleanliness, temperature and humidity in the room are provided by air conditioning and ventilation systems. Therefore, these engineering systems are becoming more common. They increasingly contribute to the comfort of our lives, as well as in general, have a beneficial effect on the human condition.

Data

The design of the heating room ventilation system requires the following input data:

1. Construction area - Semey city;

2. Heat shop. Finishing heat treatment workshop;

3. Production technologies: quenching, normalization and firing, cyanide, phosphating;

4. Mode of operation - three-shift start at 8.00, the number of shift workers 10 people, moderate work.

5. Workshop size: 22x25x15 m3; volume of 8250 m3;

6. Mass of imported material (steel) on GAZ-53A:

4. t/shift (or 500 kg/h);

7. The entrance to the store opens on two sides: 3.5x4.5 m (height);

8. Windows of fiberglass, metal plastic;

9. Direction of windows: north-south;

10. Lighting: from 21:00 to 7:00;

11. Window dimensions: 2x2.1 and 2x1.1;

1. Thermal Workshop Characteristics

The thermal workshop is designed to perform all types of heat treatment, mainly large, forging, castings and welded steel structures.

Thermal treatment is called processes whose essence consists in heating and cooling products in certain modes, as a result of which changes in the structure, phase composition, mechanical and physical properties of the material occur, without changing the chemical composition.

The following types of metal heat treatment are carried out in the thermal workshop:

annealing

training

vacation (high and low)

cementation

Annealing - heat treatment consisting in heating the metal to certain temperatures, holding and subsequent very slow cooling together with the furnace. It is used to improve the treatment of metals by cutting, reduce hardness, and obtain a granular structure. The purpose of annealing is to eliminate the chemical inhomogeneity of steels, reduce hardness to facilitate mechanical processing, etc. Annealing happens of the 1st and 2nd kind.

Quenching is heating to an optimal temperature of 900-950 ° C, holding and subsequent rapid cooling to obtain a non-equilibrium structure. Hardening increases the strength and hardness and reduces the ductility of the steel.

Tempering consists in heating steel to various temperatures, holding at this temperature and cooling at different speeds. The purpose of the release is to remove internal stresses arising during the hardening process and obtain the necessary structure. By increasing the tempering temperature, it is possible to increase the ductility and viscosity of the material while reducing hardness and strength .

Cementation - chemical-thermal treatment by surface saturation of low-carbon (C < 0.2%) or alloyed steels at temperatures of 900... 950 ° C - solid (cementation with a solid carburezer), and at 850... 900 ° C - gaseous (gas cementation) carbon with subsequent quenching and tempering. The purpose of cementation and subsequent heat treatment is to increase hardness and wear resistance.

2. Thermal Shop Process Description

Metal heat treatment is a complex chemical process. It includes annealing, normalization, hardening, softening, cementing, metal cyanide and other operations.

The purpose of heat treatment of steel is to improve its mechanical properties: increasing wear resistance, strength, hardness, impact toughness, corrosion resistance, shear resistance.

Thermal workshop equipment: main - for heating and cooling of parts, additional - for cleaning, adjustment and control of products, auxiliary - for preparation of controlled media and transportation of finished products.

The main harmful emissions in the thermal workshop are heat dissipation, radiant heat, separation of oil and water vapor in heating baths, carbon monoxide, sulfur dioxide, ammonia, nitrogen oxides, hydrogen cyanide, various hydrocarbons, etc.

Heat treatment is carried out in a protective medium to restore the structure of steel parts of SHP shaft furnaces. Before heating, the parts are heated in the chamber electric furnaces of the CHP.

Degreasing baths are installed for degreasing after hardening of parts.

The heat treatment furnaces separate carbon monoxide and nitrogen dioxide.

Steam from mineral oil (oil) from oil quench baths.

Alkaline vapour from degreasing baths (caustic soda).

Heat sources in the room: thermal furnaces, solar radiation, lighting, machines (for hardening frames, for hardening gears, for hardening with VMT rollers, for cyclic testing of springs, for cleaning the edges of springs).

Heat shop equipment description, emissions and quantity are specified in the equipment specification.

In the production rooms of the heat shop, air is combined with an exhaust fan. The flow system is also used as a heat standby. In this case, the air temperature in the room during standby heating is + 50 С.