RU2330697C2 - Method of cooling respiratory gas mix in respiratory apparatus individual protection means - Google Patents

Abstract

FIELD: protection means.

SUBSTANCE: respiratory gas mix is passed through a refrigerating fluid directly on breathing in and out. Inorganic salts capable of forming crystalline hydrates during breathing out because of interaction with water vapors with their subsequent thermal during breathing in. Inorganic salts are applied on inorganic fibrous material, after which refrigerating fluid is subjected to dehydration to add to the method efficiency.

EFFECT: higher efficiency of cooling the respiratory gas mix and its moisturising.

3 cl, 1 dwg, 1 tbl

Description

The invention relates to the field of rescue equipment, namely, personal protective equipment for respiratory organs, mainly the pendulum type, operating on chemically bound oxygen.

In recent years, both in Russia and in other countries, regenerative products based on powdered potassium superoxide, formed in the form of granules, tablets or blocks, have been used as a source of oxygen in insulating self-rescuers and respirators. These products absorb carbon dioxide and emit oxygen, however, during regeneration, large heat releases and drying of the breathing mixture occur, since water vapor also participates in chemical reactions. This leads to an increased temperature during inspiration (up to 65-75 ° C), a decrease in the relative humidity of the mixture (up to 0%) and excessive heating of the self-rescuer (respirator) structural elements. In normal operation, due to heat exchange with the walls of the respiratory tract, the temperature of the respiratory gas mixture (DHA) can drop to 45-55 ° C, however, in severe conditions, the temperature can rise to 70-80 ° C, which can lead to overheating of the body and burns the lungs .

A known method of cooling DGS, which consists in the fact that the mixture is inhaled and exhaled through an aluminum alloy tape. At the initial temperature of the DGS 75 ° C and the initial temperature of the tape 37 ° C with complete mutual heat exchange by the known method, the mixture is cooled to 20-22 ° C. The disadvantage of this method in the first place is that the gas mixture has a final relative humidity close to zero, which dramatically reduces the comfort of breathing. In addition, the cooling efficiency is insufficient, especially in severe respiration conditions, when heating can reach 60-65 ° C.

A known method of cooling the respiratory mixture is that a refrigerant is placed in a closed metal container (refrigerator) —crystalline disubstituted sodium phosphate with a melting point of 34-36 ° C, and DHA heated as a result of the regeneration reaction is passed around this container (Insulating oxygen respirator P -12. Instruction manual. - Donetsk, Central Scientific Research Laboratory of State Duma, 1969. - S.34-37). The essence of the known method lies in the fact that a homogeneous melt of refrigerant heated to + 60 ° C is poured into the refrigerator in a volume of 800-830 g and the refrigerator is cooled, moreover, at a temperature above + 34 ° C, the refrigerant melts and as a result of heat exchange through the walls of the DGS during 1 h is cooled by 1-3 ° C. After the transition to the melt, the temperature of the refrigerant begins to increase and at + 60 ° C it loses its cooling properties.

The disadvantages of this method are:

short validity period (40-60 min);

low cooling ability (1-3 ° C);

low relative humidity

The technical result of the invention is to increase the cooling efficiency of the respiratory gas mixture and its hydration.

A method for cooling a respiratory gas mixture in personal protective equipment of respiratory organs operating on chemically bound oxygen, including the use of a refrigerant, is proposed. The difference of the proposed method is that the respiratory mixture is passed during inhalation and exhalation directly through the refrigerant, and inorganic salts capable of forming crystalline hydrates as a result of interaction with water vapor with subsequent thermal decomposition during inhalation are used as the refrigerant.

The difference is also that inorganic salts are applied to the inorganic fibrous material.

Another difference is that after application to the fibrous material, the refrigerant is dehydrated.

Thus, the proposed method provides for the periodic formation and thermal decomposition of crystalline hydrates of inorganic salts during breathing.

The application of these salts to fibers of inorganic material can significantly reduce the aerodynamic resistance of the pathways of the respiratory mixture. In known cooling methods, DHS are passed through a metal strip or around a cooling element, and its cooling occurs due to heat exchange between the respiratory mixture and the metal case of the refrigerator. In the proposed method, DHA is passed directly through the refrigerant, which will not only increase the cooling efficiency, but also use the ongoing chemical reactions with the release of water vapor to increase its relative humidity.

The essence of the proposed method is illustrated by an example and a drawing, which shows a schematic diagram of its implementation.

When a person breathes, the exhaled respiratory gas mixture has a temperature of about 37 ° C and is saturated with water vapor. The cooling method is based on the absorption of heat and increasing the humidity of the inhaled gas mixture due to the evaporation of water generated during the decomposition of crystalline hydrate. The inorganic salt CaCl _{2 was} adopted as the refrigerant. The specified salt in the form of a coating 1 is applied to fibers 2 made of inorganic material, for example glass, quartz, basalt, aluminum oxide, etc., and then dehydrated. This simplifies the maintenance of respiratory protective equipment, as anhydrous salt during prolonged storage does not react with the regenerative product. The refrigerant is placed in the tube 3 and limited by stainless steel nets 4. When the water vapor contained in the exhaled mixture 5 interacts with the inorganic salt and form a crystalline hydrate:

During this reaction, the respiratory mixture is partially freed from water vapor and heated. Excess heat is dissipated into the surrounding atmosphere as the exhaled mixture passes through all components of the rescue equipment. The remainder of the water vapor takes part in the chemical operation of the regeneration of the respiratory mixture.

As mentioned above, at present, potassium superoxide is used as an oxygen source in insulating self-rescuers and respirators, while the regeneration of the respiratory mixture takes place according to the following chemical formulas:

2CO ₂ + CO ₂ = K ₂ CO ₃ + 1,5O ₂ ;

2KO ₂ + H ₂ O = 2KOH + 1,5O ₂ .

During the regeneration process, the temperature of the respiratory mixture increases to 50 ° C and higher, and the relative humidity decreases to zero, i.e. the use of such a breathing mixture can lead to overheating of the body and a burn of the lungs and extremely unpleasant uncomfortable conditions are formed on the basis of the “humidity” factor.

The proposed method involves cooling and moisturizing the respiratory mixture during inhalation. The inhaled gas mixture 6 passes through the tube 3 in the opposite direction, while passing through the refrigerant 1 containing crystalline hydrates, it decomposes with the evaporation of water by the following chemical reaction:

CaCl ₂ · 6H ₂ O = CaCl ₂ + 6H ₂ O.

During this reaction, significant heat absorption occurs and at the same time the mixture is moistened.

One of the conditions for the effectiveness of the proposed method is that the fibrous material belongs to an inorganic compound, and the salt deposited on it must be dehydrated, i.e. The condition for long-term storage of equipped equipment should be the absence of a reaction with potassium superoxide.

At a temperature of 37 ° C, the partial pressure of water vapor is 47.12 mm Hg, which corresponds to a concentration of 0.0453 g / l. For one exhalation, 1.75 L of DHA containing 0.0793 g of water vapor or 0.0044 mol enters the tube.

It is assumed that all water is sorbed by salt during exhalation and desorbed upon inhalation. For calculations, it was assumed that CaCl _{2 was} used as a refrigerant, and DHA consists of pure oxygen. The heat capacity of oxygen was taken to be 99.9 J / mol · K. Under the condition of complete adsorption and desorption of water vapor in each inhalation-exhalation cycle and the heat of decomposition of CaCl ₂ crystalline hydrate with the evaporation of water equal to 59.8 kJ / mol, the amount of absorbed energy is 0.263 kJ. At the same time, cooling of the respiratory mixture by 37 ° С with its moistening is theoretically achieved. For complete sorption of water vapor in a single cycle "inhale-exhale" is enough 0.08 g of anhydrous CaCl ₂ . Other inorganic salts may provide more significant cooling.

The table shows the characteristics of some crystalline hydrates offered as heat and moisture exchange materials.

Table
The main characteristics of crystalline hydrates Component ΔH _decomp. kJ / mol of water ΔH _decomp. , kJ / kg of water H ₂ O (shown for comparison) 40.65 2258 CaBr ₂ · 6H ₂ O 60.7 3370 CaCl ₂ · 6H ₂ O 59.8 3322 Ce ₂ (SO ₄ ) ₃ · 8H ₂ O 59.6 3368 K ₄ P ₂ O ₇ · 3H ₂ O 60.7 3372 LaCl ₂ · 7H ₂ O 59.15 3286 La ₂ (SO ₄ ) ₃ · 9H ₂ O 61.7 3426 LiCl · H ₂ O 61.3 3406 LiClO ₄ · 3H ₂ O 63.67 3537 Li ₂ SO ₄ · H ₂ O 57.0 3167 MgBr ₂ · 6H ₂ O 72.8 4046 MgSO ₄ · 7H ₂ O 58.6 3254 NaBr2H ₂ O 53.0 2944 NdCl ₃ · 6H ₂ O 63.5 3528 PrCl ₃ · 6H ₂ O 76,4 4246 Zr (SO ₄ ) ₂ · 4H ₂ O 92.25 5125

From the table it follows that as a heat-absorbing material, crystalline hydrates of salts are more effective than water. One gram of evaporated water in crystalline hydrate can absorb 2.25 times more energy than one gram of water with simple evaporation.

Using the proposed method will improve the cooling efficiency of DHA by 25-37 ° C and provide hydration to create comfortable conditions for breathing. The method simplifies the maintenance of respiratory tract protection and provides the possibility of long-term storage in running condition.

Claims (3)

1. The method of cooling the respiratory gas mixture in personal protective equipment of the respiratory system operating on chemically bound oxygen, comprising the use of a refrigerant, characterized in that the respiratory gas mixture is passed by inhalation and exhalation directly through the refrigerant, and inorganic salts capable of forming upon exhalation, crystalline hydrates as a result of interaction with water vapor followed by their thermal decomposition upon inhalation. 2. The method according to claim 1, characterized in that the inorganic salts are applied to the inorganic fibrous material. 3. The method according to any one of claims 1 and 2, characterized in that after application to the fibrous material, the refrigerant is dehydrated.