BREATHING AIR SUPPLY WITH REBREATHING SYSTEM

Abstract

An apparatus for supplying breathing air to a person includes a rebreathing system arranged in the air supply circuit, which removes CO.sub.2 at least in part present in the person's expiration air with a CO.sub.2 absorber, and treats the expiration air to supply treated air to the person again as inhalation air. The apparatus includes a condensate collection container (9) collecting water forming in the air supply circuit. The condensate collection container (9) is arranged at least in part below a reaction zone (17) of the CO.sub.2 absorber (1). At least one heat exchanger (10, 14) is provided in the CO.sub.2 absorber, via which heat from the air, which flows through the CO.sub.2 absorber and is heated as a result of the exothermic CO.sub.2 absorption reaction occurring in the reaction zone of the CO.sub.2 absorber, is dissipated.

Claims

1. A device for a breathing air supply for a person with a rebreathing system arranged in the closed air supply circuit, which removes CO.sub.2 contained in the exhaled air of the person at least partly, the device comprising: a CO.sub.2 absorber processing the air to be inhaled such that the processed air can again be fed as air to be inhaled to the person; a condensate collection tank collecting water being formed in the closed air supply circuit, wherein the condensate collection tank is arranged at least partly under a reaction zone of the CO.sub.2 absorber; and at least one heat exchanger provided in the CO.sub.2 absorber, the at least one heat exchanger removing heat from the air, which flows through the CO.sub.2 absorber and which is heated based on the exothermic CO.sub.2 absorption reaction taking place in the reaction zone of the CO.sub.2 absorber.

2. A device in accordance with claim 1, wherein the at least one heat exchanger is arranged, with respect to a flow direction of the air, behind the reaction zone in the CO.sub.2 absorber.

3. A device in accordance with claim 1, wherein the at least one heat exchanger is arranged, in at least some areas, within the reaction zone.

4. A device in accordance with claim 1, wherein the at least one heat exchanger is configured as a plate-shaped heat-conducting element.

5. A device in accordance with claim 1, wherein the at least one heat exchanger has, in at least some sections, a plastic-containing heat insulation on an outer surface thereof.

6. A device in accordance with claim 1, wherein the at least one heat exchanger has at least one heat-conducting lug extending into the reaction zone.

7. A device in accordance with claim 1, wherein the at least one heat exchanger can be cooled with ambient air.

8. A device in accordance with claim 1, further comprising at least one functional component; and a heat-conducting element, wherein the heat removed from the air by the at least one heat exchanger is sent via the heat-conducting element to the at least one functional component, which is arranged, in at least some areas, within the closed air supply circuit.

9. A device in accordance with claim 8, wherein the at least one functional component is configured as a flow sensor or as a pressure sensor or as both a flow sensor and as a pressure sensor.

10. A device in accordance with claim 1, further comprising at least one material, which binds water, arranged in the condensate collection tank.

11. A device in accordance with claim 1, wherein oxygen or an anesthetic gas is added to the air during the processing or both oxygen and an anesthetic gas are added to the air during the processing.

12. A method supplying breathing air, to a person, with a rebreathing system having a closed air supply circuit, the method comprising the steps of: connecting a device comprising: a CO.sub.2 absorber; a condensate collection tank; and at least one heat exchanger to the rebreathing system; processing the air to be inhaled with the CO.sub.2 absorber such that the processed air can again be fed as air to be inhaled to the person; arranging the condensate collection tank at least partly under a reaction zone of the CO.sub.2 absorber; collecting water being formed in the closed air supply circuit in the condensate collection tank; providing the at least one heat exchanger in the CO.sub.2 absorber; removing heat, with the at least one heat exchanger, from the air which flows through the CO.sub.2 absorber and which is heated based on the exothermic CO.sub.2 absorption reaction taking place in the reaction zone of the CO.sub.2; and providing the rebreathing system in an anesthesia device with the closed air supply circuit, or in a ventilator with the closed air supply circuit or in a a closed-circuit breathing system diving apparatus with the closed air supply circuit or in a closed-circuit breathing system rescue operations apparatus with the closed air supply circuit.

13. A method in accordance with claim 12, wherein the at least one heat exchanger is arranged, in at least some areas, within the reaction zone.

14. A method in accordance with claim 12, wherein the at least one heat exchanger is configured with a plate-shaped heat-conducting element.

15. A method in accordance with claim 12, wherein the at least one heat exchanger has, in at least some sections, plastic-containing heat insulation on an outer surface thereof.

16. A method in accordance with claim 12, wherein the at least one heat exchanger has at least one heat-conducting lug extending into the reaction zone.

17. A method in accordance with claim 12, wherein the at least one heat exchanger is cooled with ambient air.

18. A method in accordance with claim 12, wherein: the device further comprises at least one functional component; and a heat-conducting element; and heat removed from the air by the at least one heat exchanger is sent via the heat-conducting element to the at least one functional component, which is arranged, in at least some areas, within the closed air supply circuit.

19. A method in accordance with claim 18, wherein the at least one functional component is configured as a flow sensor or as a pressure sensor or as both a flow sensor and as a pressure sensor.

20. A method in accordance with claim 12 in accordance with claim 1, wherein the device further comprises at least one material, which binds water, arranged in the condensate collection tank.

21. A method in accordance with claim 12, further comprising adding oxygen or an anesthetic gas to the air during the processing or adding both oxygen and an anesthetic gas to the air during the processing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the drawings:

[0020] FIG. 1 is a sectional view of a carbon dioxide absorber configured according to the present invention with a bed of breathing lime.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Referring to the drawings, FIG. 1 shows an absorber unit 1 configured according to the present invention for absorbing carbon dioxide (CO.sub.2), as it can be used in a suitable manner in closed-circuit breathing apparatuses with rebreathing system. The housing 2 of the absorber unit 1 has a gas inlet 3, via which the breathing gas exhaled by the person is fed to the absorber 1. Further, a gas outlet 4 is provided, through which the breathing gas, from which carbon dioxide was extracted, leaves the absorber 1.

[0022] A bed of breathing lime 5, through which breathing gas exhaled by the person is sent in order to remove carbon dioxide from it at least partly, is located on a perforated plate 8. The exhaled breathing gas enters a collection space 7 under the perforated plate 8 via a duct 6 arranged centrally in the absorber housing 2 and finally reaches from there the gas outlet 4 via the perforated plate 8 and the breathing lime 5.

[0023] A condensate collection tank 9 is provided in the lower area of the collection space 7 of the absorber unit 1, i.e., likewise under the perforated plate 8 with the bed of breathing lime 5 mounted on it, in which the respective CO.sub.2 reaction zone 17 is located. The condensate generates in the absorber 9 or the moisture being formed collects in this condensate collection tank 9. The condensate is formed, on the one hand, within the absorber unit 1 based on the reaction taking place in the breathing lime 5, in which water is released, and, on the other hand, based on the specific cooling of the breathing air, which leads directly to an increase in the relative humidity of the air. The breathing gas exhaled by the person thus flows through the breathing lime 5 arranged in the absorber unit 1 from bottom to top, and the breathing gas, from which CO.sub.2 had been removed, finally flows back again into the breathing system via the gas outlet 4.

[0024] A granular mixture of calcium hydroxide (Ca(OH).sub.2) and sodium hydroxide (NaOH) is used as the breathing lime 5. The following chemical reactions take place while the breathing gas exhaled by the person flows through the bed of breathing lime 5 of the absorber unit 1:

CO.sub.2+H.sub.2O←.fwdarw.H.sub.2CO.sub.3

H.sub.2CO.sub.3+2NaOH←.fwdarw.Na.sub.2CO.sub.3+2H.sub.2O

Na.sub.2CO.sub.3+Ca(OH).sub.2←.fwdarw.CaCO.sub.3+2NaOH.

Heat and water are generated based on the reactions taking place in the reaction zone 17. Breathing limes 5 of an average configuration are able to absorb 10-15 L of CO.sub.2 per 100 g of bulk material. Furthermore, a pH indicator, which changes its color from white to violet at a low pH value and thus indicates that the breathing lime 5 has been consumed, is added to the breathing lime 5.

[0025] If the breathing lime 5 has not yet been consumed, the CO.sub.2 in the exhaled breathing gas reacts already directly at the point of entry in the lime 5, so that this area initially forms the reaction zone 17. Both heat and moisture are generated during the reaction or the absorption of CO.sub.2 based on the exothermic reaction taking place here. The reaction zone 17 migrates farther upward with increasing consumption of lime 5 within the CO.sub.2 absorber. The farther the reaction zone 17 has migrated upward, the zone in which moisture is formed is also moving in the direction of the gas outlet 4 of the CO.sub.2 absorber unit 1 and hence in the direction of the closed breathing circuit. There is basically a risk in this connection that warm and humid air will enter the closed breathing circuit, in which it will then condense and may be responsible, especially in case of condensation in the area of functional elements, such as valves or pressure and flow sensors, for the failure of these components.

[0026] To reliably avoid this effect, a heat exchanger 10, which absorbs the heat being formed in the reaction zone 17, which heat is then removed from the reaction zone 17, especially also from the CO.sub.2 absorber housing 2, is provided within the housing 2 of the CO.sub.2 absorber unit 1. The heat thus removed is passed on by means of suitable heat-conducting elements 11 to relevant components 12, which are in contact with the breathing gas in at least some areas, especially to pressure and flow sensors within the closed-circuit breathing system. A specific temperature rise takes place in the area of these components 12, so that condensation phenomena are avoided in this area. The corresponding components 12 maintain in this manner a temperature level that is above the ambient temperature, and a tendency towards condensation is thus reduced.

[0027] The higher the reaction zone 17 migrates within the bed of breathing lime 5 in the course of the consumption of the breathing lime, the more heat is absorbed by the heat exchanger 10 configured in the form of a heat-conducting plate. To further improve the dissipation of heat from the reaction zone 17, special heat-conducting lugs 13, which are in thermal contact with the heat exchanger 10, are provided within the bed of breathing lime 5. Such heat-conducting lugs 13 may generally be arranged both within the bed of breathing lime 5 and in an area arranged downstream of the bed 5 in the absorber housing 2.

[0028] According to the exemplary embodiment shown in FIG. 1, there is an additional measure for avoiding condensation cooling of the purified breathing gas leaving the bed 5. The purified gas flow is sent here through an additional heat exchanger 14, which is cooled by ambient air and hence to room temperature. A corresponding additional temperature exchange may likewise be supported by suitably provided cooling elements 15 or also by a deflected cooling air flow. It is conceivable in this connection that such a cooling air flow is blown out in the direction of the CO.sub.2 absorber unit 1 or is drawn off from that unit by means of a fan unit of a connected anesthesia, ventilation or closed-circuit breathing apparatus.

[0029] If, as is shown in FIG. 1, two heat exchangers 10, 14 are provided within the carbon dioxide absorber 1, these are heat-insulated from one another by means of a heat insulation 16. Such a heat insulation 16 may be facilitated, for example, by applying a plastic layer, especially an elastomer.

[0030] Based on the additional cooling of the breathing gas, brought about by the second heat exchanger 14, condensate is also formed, at least at times, in the area of this heat exchanger 14, and this condensate must be drawn off into the area of the condensate collection tank. The condensate now flows through the lime in counterflow to the breathing gas and finally enters the condensate collection tank 9 in the lower area of the CO.sub.2 absorber housing 2. Since the condensate flowing in from the second heat exchanger 14 in the direction of the condensate collection tank 9 must pass through the first heat exchanger 10, it is deflected such that it does not flow directly along the first heat exchanger 10 in order thus to avoid an undesired cooling. In particular, the heat-conducting lugs 13 thermally connected to the first heat exchanger 10 are not arranged beneath the surfaces of the second heat exchanger 14, at which condensate is formed and from which it will finally flow off.

[0031] The condensate is also disposed of automatically at the time of the cyclical replacement of the lime in the condensate collection tank 9 or condensate reservoir. The filling volume of the condensate collection tank 9 is preferably dimensioned for this reason such that it will not overflow within a usual replacement cycle. The filling level of the condensate collection tank 9 is visible from the outside, so that the user can detect an overfilling in time and respond correspondingly.

[0032] To facilitate the optical checking of the bed of breathing lime 5, the CO.sub.2 absorber housing 2 is manufactured in at least some sections from a translucent or transparent plastic. It is ensured in this manner that the user can reliably detect a change in the color of the lime 5. A change in the color of the lime 5 takes place as soon as this is depleted or at times also as soon as it has dried out. A change in color thus takes place in cases in which the breathing lime 5 is no longer able to assume its proper function. The change in color thus represents an important signal for the user, so that he can reliably detect that the breathing lime must be replaced.

[0033] The corresponding absorber unit 1, especially its bed of breathing lime 5, is configured such that a maximum upper lime filling level is not exceeded, so that the upper maximum filling mark always remains detectable for the user. The second heat exchanger 14 within the CO.sub.2 absorber housing 2 is arranged above the bed of breathing lime 5, so that the view to the breathing lime 5 is not made difficult for the user. Both the first heat exchanger 10 in the form of a heat-conducting plate and the second heat exchanger 14, which is cooled by room air, are manufactured from aluminum, copper, brass or a heat-conducing plastic. If the two heat exchangers 10, 14 are in the immediate vicinity of one another, a heat insulation, which preferably also has a gas-tight configuration, is provided between these. This heat insulation may, in turn, contain a plastic or elastomer material, especially silicone, TPE or EPDM. It is advantageous for the manufacture of such a heat exchanger to manufacture this by means of a die-based two-component injection molding method from a combination of heat-conductive plastics and insulating and sealing elastomers.

[0034] The technical solution according to the present invention, which is based on the fact that the cooling and the condensation of moisture are brought about specifically at one location, is characterized by a simple configuration and nevertheless guarantees a high level of safety against failure. It is especially advantageous in this connection that the moisture precipitates in an area in which a maintenance point of a breathing air supply system is located anyway. It is essential in this connection that a user be accustomed anyway to check this area visually and to change the lime cartridge at regular intervals. An even greater safety can be achieved by the coupling with an active electric heater in terms of avoiding condensation in systems for supplying persons, especially patients or rescue persons, with breathing air.

[0035] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.