Heating and ventilation project: galvanic workshop, Perm

Contents

1. Design air parameters

1.1. Design parameters of external air

1.2. Design parameters of internal air

1.3. Selection of coolant for heating and valve systems

2. Process in galvanic tse-he

3. Thermal balance of the room

3.1. Heat inputs in the premises

3.1.1. Solar Radiance Heat Transfer

3.1.2. Heat arrival through filling of light openings

3.1.3. Heat emissions from liu-dei

3.1.4. Heat inputs from electrical equipment

3.1.5. Heat inputs from equipment

3.1.6. Heat transfer from cooling material

3.1.7. Heat transfer from heated bath surfaces and drying chamber

3.1.8. Heat inputs from heating systems

3.2. Heat loss in the premises

3.2.1. Heat loss of the room taking into account air infiltration

3.2.2. Heat loss for heating of bursting air

3.2.3. Heat loss on heating of imported material

3.2.4. Heat loss on transport heating

3.2.5. Heat loss for vlah evaporation

3.3. Heat Balance Table

4. Room air balance

4.1. Galvanic tse-ha ventilation device

4.2. Selection of localizing exhaust valve devices

4.3. Determination of air volumes to be removed by local suction

4.4. Selection of localizing exhaust valve systems

4.5. Calculation of common supply and exhaust valve

4.5.1. Warm period-ode

4.5.2. Transition Period-Od

4.5.3. Cold period-od

4.6. Table of air balance sheet

5. Air distribution in room tse-ha

6. Calculation of intake valve system calorifer

7. Aerodynamic calculation

8. Equipment selection

9. Measures to combat noise and vibration of ventilation installations

10. Atmospheric air protection measures

11. Measures to protect calorifers from freezing

12. Automation

13. Measures to meet fire and explosion safety requirements

14. Heating system calculation

14.1. Calculation of heating devices

14.2. Hydraulic Account

List of literature

Applications

For category of IIA works (moderate physical work) as per [1.pp.2] permissible standards of temperature, relative humidity and air mobility at permanent workplaces are accepted:

Warm period: tv of =25 °C; air speed is not less than 0.4 m/s; relative air humidity is not more than 75%.

Cold period: tv of =17 °C; air speed is not less than 0.3 m/s; relative air humidity is not more than 75%.

1.3. Selection of heating system and coolant parameters

There are no significant heat emissions in the galvanic workshops; therefore, a heating device is necessary.

Large volume rooms are equipped with air heating combined with supply air supply.

Since there are permanent workstations located at a distance of less than 2 m (see the design task) from the windows in the external walls, local heating devices are installed to protect the workers from falling cold air flows. According to [1, pr. 11] the water heating system is accepted at the temperature of the coolant in the supply and return pipeline t1 = 150 ° C and t2 = 70 ° C, respectively. The heating system is a double-tube system with heating devices and cast-iron radiators MS 140AO. The shop accepts a non-elevator heating system.

Calculation of the number of heating devices and the number of sections in them is given in item 14.

To prevent cold air flows from entering the shop through the gates, an air-heat curtain is provided in the outer walls.

2. Process in galvanic shop

The basis of the technology of galvanic workshops is the application of protective coatings on the surfaces of products of various purposes.

Measures for pre-treatment of the surface of articles (before coating) are usually carried out in special rooms and consist in mechanical, chemical or electrochemical treatment of the surface of articles.

The technological process of galvanic coating workshops usually characterizes the following set of measures:

1. Preparation (cleaning) of the product surface:

1) Machining (blasting, grinding, blasting, punching, use of sand blasting and shot blasting chambers, etc.);

2) Chemical or electrochemical degreasing of articles in organic solvents, in solutions of alkali or alkali metal salts, followed by washing in hot water. Degreasing may not be used under condition of preliminary annealing of articles;

3) Etching and decapitation of articles in solutions of acids and alkalis to remove oxides and other contaminants.

2. Coating in galvanic baths followed by surface treatment of articles (washing in clean running or heated water to remove traces of electrolyte, drying, polishing with decorative coating, etc.).

In galvanic workshops, the application of metal coatings on products is aimed at giving their surfaces specific properties. For example, there were:

(a) Protection against atmospheric corrosion.

For steel in this case, galvanizing, cadmation (in the marine climate), phosphating, oxidation, copper and brass are used, for copper and its alloys - nickel, copper, oxidation;

b) Protective and decorative treatment.

For steel, zinc and aluminum alloys, nickel and chromium are used, for copper and its alloys - nickel, silver or gilding;

c) Corrosion protection in liquid media.

For products in tap water, galvanizing is used, in sea water cadmation, in alkaline solutions - nickel plating, in solutions of sulfuric acid, sulfuric acid and sulfurous compounds - lead plating, for containers for food products pudding, for stores of gasoline or kerosene - galvanizing;

d) Increase wear resistance of the article.

It is achieved by chrome plating, nickel plating or surface ironing.

When treating the surfaces of products, the main equipment are baths for degreasing, etching, coating, decapitation, etc. During these operations and when applying galvanic coatings in the air of the premises, various hazards are released in the form of vapors, gases and hollow drops (with the release of hydrogen). So, the etching of ferrous metals is produced in sulfuric and hydrochloric (less often in nitric) acids, non-ferrous metals in nitric (less often hydrofluoric) acid, aluminum in alkali solutions. After the main processes (degreasing, etching, application of protective and decorative coatings), the products must be washed in special washing baths.

Depending on the chemical composition of the solution, all processes taking place in etching and galvanic baths can be divided into three main groups, acidic, alkaline and cyanide.

Acidic processes include etching, decapitation and application

a number of galvanic coatings flowing in an acidic medium, such as zinc, nickel, copper, tin, chromium, lead. Alkaline processes include degreasing, alkaline tinning, funneling. Processes with the release of poisonous hydrogen cyanide include: galvanization, copper, cadmation, silver, etc., as well as some types of etching and decapitation.

4. Air balance of the room

4.1. Galvanic Ventilation Unit

Technological processes in galvanic workshops are accompanied by releases of harmful substances into the atmosphere. The removal of harmful substances from the workshop is carried out at the places of their release through local suction pumps embedded in or attached to production equipment.

Local suction from baths for degreasing parts with organic solvents, from baths for cyanide processes, chromium plating and nickel plating processes should be combined into independent systems. From the cold and hot washing baths, the exhaust is not installed, except for the washing baths after etching in nitric acid. Tanks, collectors, meters for dissolution of acids, alkalis and salts must be equipped with covers. The amount of air removed through local suction from them is determined by the suction rate through leaks of 0.7 m/s at cold and 1 m/s at heated solutions.

Local suction systems from baths with cyanide solutions, nitric and hydrochloric acids shall have backup fans with their automatic switching on when the main one stops.

Plenum ventilation in all main departments of galvanic and etching shops is provided for mechanically and is calculated for full compensation of air removed by local and general exhaust systems throughout the year. Of the total inflow, a portion of it, approximately 5%, is supplied to adjacent rooms that do not have toxic emissions and dust to create pressure in them. The main volume is supplied to the upper zone by dispersed perforated air ducts of the MIC 2.00.000 - 02, 4 pcs. The project adopted two systems of plenum general ventilation, one of which works around the clock.

4.2. Selection of devices in localizing exhaust ventilation

To remove air from galvanic baths, double-breasted local suction pumps of the overturned type are used. Local suction is installed at baths containing hazards (Ct ≥1 - toxicity coefficient of harmful substances emitted from the surface of the solution). Local suction is installed on the long side of the bath, which ensures better capture of harmful substances.

4.4. Selection of localizing ventilation systems

In exhaust ventilation systems (B3, B4, B5), double-breasted overturned suction pumps of the design GPI "Proektpromventschyash" 900 * 450 are used. Exhaust systems removing air containing alkali and water vapors are combined into a single system, chromium anhydrite, hydrogen cyanide are removed separately. Exhaust fans of the local system are located on the roof of the building. Air ducts are laid at a slope of 0.0050.1 to the fan and moisture is removed from it. It should be borne in mind that aerosols and salts are deposited in the on-board suction and air ducts of exhaust systems; for cleaning from them it is necessary to provide manholes and detachable connections.

9. Measures to combat noise and vibration of fan installations

The noise level is a significant criterion for the quality of ventilation systems, which must be taken into account when designing.

To reduce the noise of the source itself, it is necessary to:

- strive for the fan to operate in maximum efficiency mode at the specified volumetric flow rate and mains resistance;

- do not install the fan with pressure margin;

- make smooth air supply to the fan inlet pipe;

- pay special attention to balancing of fan impeller;

- air velocity in air duct systems does not exceed permissible ones.

In general, to ensure good sound insulation, the following is recommended:

- vibration isolate ventilation units using spring shock absorbers;

- air ducts are connected to fans through flexible inserts;

- use sound absorbing linings to reduce the noise level in the ventilation chambers themselves;

- for building structures use structures of increased soundproofing; use "floating" floor structures in ventilation chambers.

11. Measures to protect calorifers from freezing

When using water as a coolant to prevent its freezing in calorifers, the heating surface area must be taken with a margin not exceeding 10%. At the same time, they provide:

1) The water velocity in the heater tubes shall not be less than 0.12 m/s;

2) Calorifers with vertical tubes should be installed strictly vertically, and with horizontal tubes - strictly horizontally to avoid accumulation of air in them;

3) In case of heat carrier - water, it is recommended to connect calorifers according to a direct-flow cross-cross scheme: supply heat carrier to the first row of calorifers along the air flow and remove it from the last row;

4) Air collectors should be installed at all upper points of the piping, not air cranes;

5) Automatic protection of calorifers against freezing shall be carried out when the system is turned off, if it is possible to penetrate the calorifer of air with a negative temperature, and when the system is operating, if there is a possible pressure drop or violation of the temperature schedule of the network water at a negative temperature of air entering the calorifer.

12. Automation

The level of automation and control of systems should be chosen depending on technological requirements and economic feasibility.

Monitoring devices should be installed for measurement: in systems of at-precision ventilation - temperature of external and plenum air, steam meters of coolant, hydraulic resistance of filter; in subscriber thermal inputs with no eluvator connection - temperature and water pressure in the supply pipeline of the thermal network; pressure at inlet and outlet of heating system, temperature of return water from heating system. Air control and monitoring sensors should be located at specific points in the serviced area of the room in places where they are not affected by heated or cooled surfaces and plenum air jets.

Automatic protection of calorifers from freezing should be provided. In ventilation systems actuators of valves of external and removed air are blocked. Automatic blocking of fans of local suction systems that do not have backup fans with process equipment shall ensure equipment shutdown in case of fan failure, and if it is impossible to stop process equipment - actuation of alarm.

For electric motors of fans of the air-heat curtain there is a blocking with a mechanism for opening the gates served by curtains. The actuation of the air curtain should be blocked with the opening of the gates, doors and process openings.

Automatic shutoff of the curtain should be provided after closing the gates, doors or process openings and restoring the normalized air temperature of the room, providing for a reduction in the coolant flow rate to the minimum one that ensures non-freezing of water.

13. Measures ensuring fire and explosion safety conditions

Ventilation systems in case of non-compliance with the current fire design standards can be the cause of fires and explosions, as well as contribute to the rapid spread of fire and smoke throughout the building. Therefore, when designing the ventilation system, it is necessary to provide a set of engineering solutions aimed at preventing people from being exposed to smoke and toxic products formed during a fire. Such solutions include the selection of ventilation systems depending on the category of the room for explosion and fire hazard, structural measures, design of emergency and smoke ventilation, increased requirements for air ducts, equipment, its placement, as well as automatic blocking of ventilation systems with fire extinguishing and alarm installations.

Ducts should be designed from non-combustible materials.

Transit air ducts and manifolds after crossing the ceiling or fire partition of the serviced or other room throughout the entire length to the room for ventilation equipment should be provided with a fire resistance limit of at least 0.5 hours.

Places of passage of transit air ducts through walls, partitions and floors of buildings (including in casings and shafts) should be sealed with non-combustible materials, providing a normalized fire resistance limit of the crossed fence.

It is necessary to use spark-proof or intrinsically safe fans and motors or ejection motives, for example, in exhaust ventilation systems of degreasing areas in organic solvents; Suction of the spirit should not be combined in 1 exhaust ventilation system with impurities that can form flammable mixtures. Static electricity removal devices shall be provided. Systems with a small number of local suction should be used, ventilation chambers should be isolated from neighboring rooms with fire resistance

fences.

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