Method and apparatus for anesthetic gas reclamation with compression stage

• US 20060254589A1
• Filed: 05/11/2006
• Published: 11/16/2006
• Est. Priority Date: 05/13/2005
• Status: Active Grant

• Current Assignee: Anesthetic Gas Reclamation LLC
• Original Assignee: Anesthetic Gas Reclamation LLC
• Inventors: Berry, James M., Morris, Steve
• Granted Patent: US 7,669,438 B2
• Time in Patent Office: Days
• US Class Current: 128/205.120
• CPC Class Codes: A61M 16/009 Removing used or expired gases or anaesthetic vapours filtering, sterilising or disinfecting the exhaust air in drainage systems A61M1/784; bacterial filters in the expiratory path A61M16/1065
• CPC Class Codes: A61M 16/0093 by adsorption, absorption or filtration
• CPC Class Codes: A61M 2202/0007 introduced into the body
• CPC Class Codes: A61M 2202/0208 Oxygen
• CPC Class Codes: A61M 2202/03 Gases in liquid phase, e.g. cryogenic liquids
• CPC Class Codes: A61M 2205/3606 cooled

Abstract

A method and apparatus are disclosed for recovering and separating anesthetic gas components from waste anesthetic gases to be purged from a healthcare facility. Prior to a condensation step, a compressor is used to increase the waste anesthetic gas pressure in order to facilitate condensation of anesthetic gas components at higher temperatures and in greater amounts than through condensation at lower pressures. Condensing the anesthetic gas components from the compressed waste anesthetic gas stream is then achieved using conventional condensation systems, which remove anesthetic gases as either liquid condensates or solid frosts. A preferred embodiment of the invention may be used with existing high-flow scavenging or reclamation systems but is more preferably used with low-flow scavenging or reclamation systems, which employ intelligent waste anesthetic gas collection units to minimize the ingress of atmospheric gas when no waste anesthetic gas is to be purged from the healthcare facility.

Claims

1. A method of removing and separating gaseous anesthetics from a waste anesthetic gas stream to prevent atmospheric venting of gaseous anesthetics from a healthcare facility, said method comprising the steps of:

collecting said waste anesthetic gas stream from an anesthetizing machine (12A, 12B, 12C),

compressing said received waste anesthetic gas stream to a pressure above atmospheric pressure using a compressor (42) with at least one compression stage,

cooling said compressed gas stream by passing said compressed gas mixture over a cooling surface (136, 236A, 236B) characterized by a surface temperature gradient such that said gas stream passes thereover in a direction from a warmer to a colder temperature,

condensing said gaseous anesthetics from said compressed gas stream,

separating said condensed anesthetics from said compressed gas stream,

venting to atmosphere (46) said gas stream absent said condensed anesthetics.

2. The method of claim 1 in which said step of collecting said waste anesthetic gas stream comprises the steps of:

receiving said gas stream from an anesthetizing machine (12A, 12B, 12C) into a chamber (32A, 32B, 32C),

detecting (40A, 40B, 40C) a presence of said gas stream received in said chamber (32A, 32B, 32C),

periodically fluidly coupling said chamber to a vacuum manifold by a selectively isolable flow path (34A, 34B, 34C) in response to said presence of said gas stream received in said chamber (32A, 32B, 32C), and

transferring said gas stream received in said chamber (32A, 32B, 32C) to a compressor (42) by said selectively isolable flow path (34A, 34B, 34C) and said vacuum manifold (16), whereby

said chamber (32A, 32B, 32C) and said selectively isolable flow path (34A, 34B, 34C) cooperate to minimize ingress of an atmospheric gas into said vacuum manifold (16) when no said waste anesthetic gas stream is exiting said anesthetizing machine (12A, 12B, 12C).

3. The method of claim 1 wherein said step of condensing said gaseous anesthetics from said waste anesthetic gas stream is conducted at a pressure and temperature to cause said gaseous anesthetics to be condensed as liquids.

4. The method of claim 1 wherein said step of condensing said gaseous anesthetics from said waste anesthetic gas stream is conducted at a pressure and temperature to cause said gaseous anesthetics to be condensed as solids.

5. The method of claim 4 wherein said condensed gaseous anesthetics undergo desublimation onto an outer surface of said cooling surface (136) such that said gaseous anesthetics with a higher desublimation point deposit on a warmer portion (160, 162) of said cooling surface (136) and said gaseous anesthetics with a lower desublimation point deposit on a colder portion (163, 164) of said cooling surface (136).

6. The method of claim 5 further comprising the step of:

heating said cooling surface (136) to selectively remove solid anesthetics thereon as liquid anesthetics such that said liquid anesthetics are sequentially separated and collected based upon melt point temperature.

7. The method of claim 2 wherein said step of condensing said gaseous anesthetics from said waste anesthetic gas stream is conducted at a pressure and temperature to cause said gaseous anesthetics to be condensed as liquids.

8. The method of claim 2 wherein said step of condensing said gaseous anesthetics from said waste anesthetic gas stream is conducted at a pressure and temperature to cause said gaseous anesthetics to be condensed as solids.

9. The method of claim 8 wherein said condensed gaseous anesthetics undergo desublimation onto an outer surface of said cooling (136) surface such that said gaseous anesthetics with a higher desublimation point deposit on a warmer portion (160, 162) of said cooling surface (136) and said gaseous anesthetics with a lower desublimation point deposit on a colder portion (163, 164) of said cooling surface (136).

10. The method of claim 8 further comprising the step of:

heating said cooling surface (136) to selectively remove solid anesthetics thereon as liquid anesthetics such that said liquid anesthetics are sequentially separated and collected based upon melt point temperature.

11. The method of claim 1 further comprising the steps of:

expanding said gas stream through an expansion valve (43) prior to atmospheric venting (46) thereof, and collecting in a receiver (45) liquefied anesthetic components condensed by expanding said gas stream through said expansion valve (43).

12. The method of claim 2 further comprising the steps of:

expanding said gas stream through an expansion valve (43) prior to atmospheric venting (46) thereof, and

collecting in a receiver (45) liquefied anesthetic components in a receiver condensed by expanding said gas stream through said expansion valve (43).

13. The method of claim 1 further comprising the steps of:

expanding said gas stream through a turbine (44) prior to atmospheric venting (46) thereof, and

collecting in a receiver (45) liquefied anesthetic components in a receiver condensed by expanding said gas stream through said turbine (44).

14. A system for preventing venting to the atmosphere of anesthetic gas components of waste anesthetic gas from a healthcare facility comprising:

a waste anesthetic gas collection unit (15A, 15B, 15C, 30A, 30B, 30C) which collects waste anesthetic gas from an anesthetizing machine (12A, 12B, 12C),

a vacuum manifold (16) for drawing said waste anesthetic gas from said waste anesthetic gas collection unit (15A, 15B, 15C, 30A, 30B, 30C) into a compressor (42),

a compressor (42) consisting of at least one compression stage for elevating said waste anesthetic gas to a pressure higher than atmospheric pressure,

a first heat exchanger/condenser (222A) having an inlet fluidly coupled to a flow line (239) from said compressor (42) and an outlet, said first heat exchanger/condenser (222A) also having a first cooling coil (236A) positioned therein with an outlet of said first cooling coil (236A) fluidly coupled to a flow line (227) to a refrigerant sink, said first cooling coil (236A) having an inlet,

a second heat exchanger/condenser (222B) having an inlet which is fluidly coupled to said outlet of said first heat exchanger/condenser (222A) and an outlet which is fluidly coupled to an atmospheric vent line (46), said second heat exchanger/condenser (222B) also having a second cooling coil (236B) positioned therein with an outlet of said second cooling coil (236B) fluidly coupled to said inlet of said first cooling coil (236A) and an inlet of said second cooling coil (236B) fluidly coupled to a flow line (221) from a source of refrigerant (220),

said first heat exchanger/condenser (222A) having a first vessel (23) for collecting water liquefied from said waste anesthetic gas within said first heat exchanger/condenser (222A), and

said second heat exchanger/condenser (222B) having a second vessel (24) for collecting anesthetic components liquefied from said waste anesthetic gas within said second heat exchanger/condenser (222B).

15. The system of claim 14 further comprising:

an expansion valve (43) fluidly coupled to said outlet of said second heat exchanger/condenser (222B), said expansion valve (43) for reducing said pressure of waste gas to be vented, and

a receiver (45) fluidly coupled between said expansion valve (43) and said atmospheric vent line (46), said receiver (45) for collecting liquefied anesthetic components condensed by reducing said pressure of said waste gas.

16. The system of claim 14 wherein said waste anesthetic gas collection unit (15A, 15B, 15C, 30A, 30B, 30C) comprises:

a chamber (32A, 32B, 32C) for receiving said waste anesthetic gas from said anesthetizing machine (12A, 12B, 12C),

a detector (40A, 40B, 40C) for detecting a presence of said waste anesthetic gas received in said chamber (32A, 32B, 32C), and

a selectively isolable flow path (34A, 34B, 34C) which periodically fluidly couples said chamber (32A, 32B, 32C) to a vacuum manifold (16) in response to said presence of said waste anesthetic gas received in said chamber (32A, 32B, 32C), whereby

said chamber (32A, 32B, 32C) and said selectively isolable flow path (34A, 34B, 34C) cooperate to minimize ingress of an atmospheric gas into said vacuum manifold (16) when no said waste anesthetic gas is exiting said anesthetizing machine (12A, 12B, 12C).

17. A system for preventing venting to the atmosphere of anesthetic gas components of waste anesthetic gas from a healthcare facility comprising:

a waste anesthetic gas collection unit (15A, 15B, 15C, 30A, 30B, 30C) which collects waste anesthetic gas from an anesthetizing machine (12A, 12B, 12C),

a vacuum manifold (16) for drawing said waste anesthetic gas from said waste anesthetic gas collection unit (15A, 15B, 15C, 30A, 30B, 30C) into a compressor (42),

a compressor (42) consisting of at least one compression stage for elevating said waste anesthetic gas to a pressure higher than atmospheric pressure,

a heat exchanger/condenser (22) having an inlet fluidly coupled to a flow line (139, 239) from said compressor (42) and an outlet which is fluidly coupled to an atmospheric vent line (46), said heat exchanger/condenser (22) also having a cooling coil (136, 236A, 236B) positioned therein with an outlet of said cooling coil (136, 236A, 236B) fluidly coupled to a flow line (127, 227) to a refrigerant sink, said cooling coil (136, 236A, 236B) having an inlet fluidly connected to a flow line (121, 221) from a source of refrigerant (120, 220),

said heat exchanger/condenser (22) having at least one vessel (24A, 24B) for collecting liquefied anesthetic components from said waste anesthetic gas within said heat exchanger/condenser (22).

18. The system of claim 17 further comprising:

an expansion valve (43) fluidly coupled to said outlet of said heat exchanger/condenser (22), said expansion valve (43) for reducing said pressure of waste gas to be vented, and

a receiver (45) fluidly coupled between said expansion valve (43) and said atmospheric vent line (46), said receiver (45) for collecting liquefied anesthetic components condensed by reducing said pressure of said waste gas.

19. The system of claim 17 wherein said waste anesthetic gas collection unit (15A, 15B, 15C, 30A, 30B, 30C) comprises:

a chamber (32A, 32B, 32C) for receiving said waste anesthetic gas from said anesthetizing machine (12A, 12B, 12C),

a detector (40A, 40B, 40C) for detecting a presence of said waste anesthetic gas received in said chamber (32A, 32B, 32C), and

a selectively isolable flow path (34A, 34B, 34C) which periodically fluidly couples said chamber (32A, 32B, 32C) to a vacuum manifold (16) in response to said presence of said waste anesthetic gas received in said chamber (32A, 32B, 32C), whereby

said chamber (32A, 32B, 32C) and said selectively isolable flow path (34A, 34B, 34C) cooperate to minimize ingress of an atmospheric gas into said vacuum manifold (16) when no said waste anesthetic gas is exiting said anesthetizing machine (12A, 12B, 12C).

20. The system of claim 17 further comprising:

a turbine (44) fluidly coupled to said outlet of said heat exchanger/condenser (22), said turbine (44) for reducing said pressure of waste gas to be vented (46), and

a receiver (45) fluidly coupled between said turbine (44) and said atmospheric vent line (46), said receiver (45) for collecting liquefied anesthetic components condensed by reducing said pressure of said waste gas.