XI Международная студенческая научная конференция Студенческий научный форум - 2019

With complete isolation of the building, the backwater is provided by compressed air from cylinders, which are dispensed using a reducer. Backwater is an increase in air pressure above atmospheric before an obstacle due to high-speed head or indoors due to the effect of forced ventilation or an additional supply of compressed air. At the same time, the number of compressed air cylinders simultaneously activated in operation and the required hourly air flow from the cylinders depend on the excess pressure (overpressure) of the air and the inner surface area enclosing the shelter sealing circuit (the total area of walls, flashover and floor) [1,2].

The compressed air system is a set of technical means (compressors, cylinders, gearboxes, pipelines and compressed air distribution units) designed to create and replenish stocks of compressed air, store and deliver it at the right time to the consumer in order to:

- maintain excess air pressure in the building;

- purging sanitary inspection rooms during their work;

- supply of air to working diesel engines for combustion with closed gas-air ducts.

The compressed air system has three modes of operation:

- mode of filling cylinders with air;

- storage mode stocks of air in cylinders;

- air delivery mode to consumers.

Air supply is carried out in two ways:

- with a stabilized (estimated) flow rate - for the protective structure as a whole;

- with stabilized pressure - for vestibule-locks, transfer chambers, etc.

However, in the full isolation mode, the free release of air through the switchgear can be used not only to maintain the backwater in the building, but also to reduce the temperature of the air released into the building, thereby lowering the overall temperature of the microclimate and obtaining electricity when converting kinetic energy air flow. Such a device can be a detander. Turbo expanders are continuous blade machines, in which the flow passes through fixed guide channels (nozzles) that convert part of the potential energy of gas into kinetic, and a system of rotating rotor blade channels, where the energy of the flow is transformed into mechanical work, as a result what is the cooling gas. They are divided by the direction of flow into the divective, centrifugal and axial; according to the degree of gas expansion in the nozzles - into active and reactive; according to the number of expansion stages - into single and multi-stage. The most common reactive single-foamy centripetal detander, developed by P. L. Kapitsa. The deceleration of turbine expanders is carried out by an electric generator, hydraulic brake, supercharger, pump. Turbine expanders are mainly used in installations with a low-pressure refrigeration cycle of 0.4–0.8 Mn / m² (4–8 kgf / cm²) for volumetric (physical) gas flow rates of 40–4000 m³/h. Turboexpanders were created for low, medium and high pressure refrigeration cycles with gas flow rates of 1.5–40 m³/h. These machines are characterized by small dimensions (working wheel diameter of 10–40 mm) and high rotor speed (100,000–500,000 rpm).

There are several types of turboexpanders that can be used for this purpose, including: rotary, piston, screw and turbine. The last of these are the most valuable, because they are able to work with a large amount of gas and large differences in its pressure (in ratios up to 5:1). The turbine expander power depends on the amount of gas, its temperature and pressure drop. This power can be used not only for generating electricity, but also for other purposes mentioned above.

Work force in the turbine arises due to a change in kinetic energy. The transformation of kinetic energy in the turbine takes place in the channels of the stationary nozzle apparatus and on the working blades located on the rotating disk of the turbine (in a piston machine, the working force is created by the pressure of a fixed mass of gas or vapor).

The thermodynamic principles of calculating all expanders are the same, and the purpose of the calculation is to determine the work that can be obtained from a certain amount of gas for a given initial and final parameters of the working fluid.

The expander power depends on the design features of the detander, the choice of the working fluid, the flow through it. The biggest costs are turbines; they are able to develop large capacity at small sizes.

Both compressors and detander are the main units of modern thermal power plants.

The use of special constructions in the air distribution system can be implemented without significant design changes of the existing air distribution schemes.

The advantages of using a turbo-expander as an autonomous source of power supply are obvious, since they utilize their own energy resources of the compressed air system and are easy to operate.

Thus, the proposed method of air distribution with the inclusion of a turboexpander allows you to convert the kinetic energy of the outgoing air stream into electrical energy and significantly lower the air temperature.

Bibliography

1. SNiP II-11-77 «Zashchitnye sooruzheniya grazhdanskoj oborony».

2. Prikaz MCHS RF ot 15 dekabrya 2002 g. № 583 «Ob utverzhdenii i vvede-nii v dejstvie pravil ehkspluatacii zashchitnyh sooruzhenij grazhdanskoj oborony»