On-site CO2 Generation for Poultry Stunning

Abstract

An apparatus for stunning animals with an exhaust gas mixture includes a stunning chamber located at the processing site into which an equal number of animals selected for stunning are contained, and a combustion chamber located at the processing site for combusting the mixture of gases to provide therefrom an exhaust gas mixture including carbon dioxide for stunning the animals in the stunning chamber. Related methods and exhaust gas mixtures are also provided.

Description

[Technical field]

[0001] 2. Background of the Invention The present invention relates to the stunning of animals for food processing, and in particular to an apparatus and method for stunning animals, such as poultry, with an industrial gas. [Background technology]

[0002] Stunning of animals, such as poultry, requires an atmosphere of carbon dioxide (CO2), nitrogen (N2), and oxygen (O2). The terms "carbon dioxide" and "CO2", "nitrogen" and "N2", "oxygen" and "O2" are used interchangeably herein. The terms "stunned" or "stunning" are used in the animal food processing industry and as used herein, refer to the process of rendering an animal unconscious prior to slaughtering the animal for consumption. The stunning process ensures that the animal, such as poultry, does not experience discomfort or pain. Stunning of poultry, for example, requires high concentrations of CO2 before the birds are slaughtered for further processing. Poultry stunning and equipment used for poultry stunning are known in the art.

[0003] Traditionally, the supply of industrial gases to poultry stunning systems has been provided by on-site industrial bulk gas storage tanks (carbon dioxide, nitrogen, and oxygen). The terms "on-site" and "bulk" as used herein refer to large tanks, containers, or vessels located or installed at the processor's facility or site, into which the respective liquid is filled from tanker trucks that deliver the liquid to the on-site tanks during scheduled deliveries or as needed in an emergency to meet increased demand at the stunning facility. In most applications, the bulk tank contains the liquid. The bulk tank then delivers the liquid through a pipeline or other intermediate process where the liquid phase is transformed into the gas that will be used in the stunning chamber. The gases are mixed in various concentrations to obtain a predetermined stunning gas mixture. The stunning gas mixture selected is one that minimizes stress to the animal and thus increases both the yield and quality of edible meat obtained from the animal during subsequent processing.

[0004] Since stunning is one of the first necessary or initial steps in poultry meat processing, a reliable supply of carbon dioxide is essential for the on-site stunning process. If the supply of carbon dioxide for the stunning process is interrupted, the production of the poultry meat processing facility must be stopped, resulting in adverse economic impacts for the poultry (food) processor. Known stunning facility operators have their own on-site bulk storage tanks, which are currently supplied from bulk carbon dioxide tankers with scheduled deliveries. Unfortunately, CO2 is at the highest risk of interruption of all gases used for the stunning gas mixture. This is because CO2 is derived from a feed gas stream supplied by a feed gas supplier, e.g., a refinery, an ethanol plant, etc. And the feed gas contracts entered into by the feed gas supplier allow for stoppages and / or interruptions of the feed gas stream due to maintenance, temporary shutdowns, power outages, idling, and turnaround repairs of the plant from which the CO2 is derived. In fact, the supplier, and therefore the operator of the gas stunning facility, has little control over the delivery of a continuous supply of CO2, compared to the delivery of oxygen and nitrogen, gases that are drawn from the air. Therefore, a reliable supply of CO2 for the stunning gas mixture used in the processes involved is more susceptible to interruption than that of oxygen and nitrogen.

[0005] With reference to Fig. 1, a known stunning facility susceptible to a CO2 outage or interruption as described above uses a stunning system having a stunning chamber 100 for animals 102, such as poultry (chickens or otherwise). To the stunning facility in which the stunning chamber 100 is used, certain amounts or molecules of O2, N2, and CO2 are delivered in liquid bulk. Liquid oxygen (LOX), liquid nitrogen (LIN), and liquid carbon dioxide (LCO2) tanker trucks (not shown) deliver the respective liquid products to corresponding bulk tanks 104 (bulk liquid O2), 106 (bulk liquid N2), 108 (bulk liquid CO2) located on the premises of the stunning facility. Each of the bulk tanks 104, 106, 108 has a corresponding outlet and a corresponding pipeline 104', 106', 108' that connects each one of the bulk tanks to the inlet of a corresponding vaporizer 114, 116, 118. Each of the vaporizers 114, 116, 118 has an outlet connected to a corresponding pipeline 114', 116', 118', which is connected to a corresponding inlet of the mixing system 110 or skid. The bulk tanks 104, 106, 108 are pressurized, thereby creating a tank head pressure within each tank, forcing the corresponding bulk liquid out of the tank and delivered to a respective one of the vaporizers 114, 116, 118, preferably in a controlled and continuous manner as required for the operation. The vaporizers 114, 116, 118 receive the bulk liquids and vaporize them, i.e., the bulk liquids change from liquid to gas phase, respectively, thereby facilitating mixing with gases in the downstream mixing system 110 or skid.

[0006] At the skid 110, the gaseous portions of each bulk liquid from the tanks 104, 106, 108 are mixed and then fed through another pipeline 110' to and in communication with the stunning chamber 100. The liquid streams leaving each bulk tank 104, 106, 108 are preferably pressurized, although other methods of delivering the bulk liquid from the tanks 104, 106, 108 may be utilized.

[0007] A mixing system 110 provides a gas stunning mixture 112 to the stunning chamber 100. Three gases are mixed in various concentrations in the skid 110 to provide a gas stunning mixture 112 that is selected to optimize meat quality and yield during stunning and subsequent processing. The type and number of animals to be stunned in the chamber 100 will determine the specific ratio or concentration of each gas that will be used in the gas stunning mixture 112. The subsequent process for the animals being stunning may also determine the ratio or concentration of each gas that will be used in the gas stunning mixture 112.

[0008] As is evident from the known stunning system of Figure 1, the stunning system depends on a reliable supply of CO2 to stunning the poultry for subsequent processing. CO2 gas is the primary, i.e. most important, gas for the stunning gas mixture 112. However, CO2 outages, interruptions, and / or other possible force majeure situations may adversely affect the reliable delivery of liquid CO2 to the bulk storage tank 108 for the production of CO2 gas to be used in the stunning gas mixture 112 of the stunning system. Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, there is a need for an alternative to reliance on delivery of bulk liquid CO from off-site that can generate "CO on demand" for stunning purposes, and that eliminates the disadvantages suffered by food processors as described above. [Means for solving the problem]

[0010] Summary of the Invention Inventive embodiments provide a flue gas or exhaust gas mixture as a stunning gas mixture from an oxy-fuel combustion process on-site at a processor's site or facility that provides carbon dioxide (CO2) and other gases required in a stunning system for animals, such as poultry. The oxy-fuel combustion apparatus and associated method are located in the same processing site or facility as that of the stunning system. Natural gas or propane already present at the processing site and gaseous oxygen from bulk liquid tanks, which are more readily available than CO2, are delivered to the oxy-fuel burners of the combustion process. References to natural gas herein include propane. Combustion of gaseous oxygen, air, and natural gas in an oxy-fuel burner results in a fuel gas consisting of CO2, nitrogen (N2), oxygen (O2), and water (H2O). Combustion of natural gas in an air-oxy-fuel burner, which can use different amounts of oxidizers along with oxygen and air, also results in a fuel gas consisting of CO2, nitrogen (N2), oxygen (O2), and water (H2O). If the combustion gas or oxidant for the burner is 100% oxygen, the resulting fuel gas can contain as much as 90% CO2. Oxygen and natural gas (or propane) are more readily and reliably available, significantly reducing the risk of supply interruptions because the CO2 is produced on-site and on demand.

[0011] In the present application, an apparatus for stunning animals with an exhaust gas mixture is provided, comprising a stunning chamber located at the processing site into which an equal number of animals selected for stunning are accommodated, and a combustion chamber located at the processing site for combusting the mixture of gases to provide therefrom an exhaust gas mixture comprising carbon dioxide for stunning the animals in the stunning chamber.

[0012] In certain embodiments, the apparatus further includes a flow skid located at the process site upstream of and in fluid communication with the combustion chamber to receive gaseous oxygen, air, and natural gas or propane and provide a proportion of each of the gaseous oxygen, air, and natural gas or propane for the combustion mixture to be provided to the combustion chamber.

[0013] In certain embodiments, the apparatus further includes a heat exchanger located at the processing site downstream of the combustion chamber to receive the exhaust gas mixture and cool it before it is delivered to the stunning chamber.

[0014] In certain embodiments, the apparatus further includes a condenser located at the processing site downstream of and in fluid communication with the heat exchanger to receive and dry the exhaust gas mixture, and a filter located at the processing site downstream of and in fluid communication with the condenser to receive the dried exhaust gas mixture and remove particulate matter from the dried exhaust gas mixture.

[0015] In certain embodiments, the apparatus further includes a compressor or blower located at the processing site downstream of and in fluid communication with the heat exchanger to receive the exhaust gas mixture for delivery to the stunning chamber.

[0016] In certain embodiments, the exhaust gas mixture further comprises nitrogen and oxygen.

[0017] In certain embodiments, gaseous oxygen, air, and natural gas are available at the processing site, or propane is available at the processing site in lieu of natural gas.

[0018] In certain embodiments, the combustion chamber further includes an oxy-fuel burner or an air-oxy-fuel burner for combusting the mixture of gases.

[0019] In certain embodiments, the apparatus further includes a boiler located at the processing site with which the exhaust gas mixture from the combustion chamber is contacted, and a heat exchanger located at the processing site to receive at least a portion of the exhaust gas mixture, the heat exchanger configured and arranged to return a cooled exhaust gas mixture for delivery to the stunning chamber.

[0020] In certain embodiments, the heat exchanger includes a cooling tower.

[0021] In certain embodiments, the percentage of carbon dioxide in the exhaust gas mixture is in the range of 11% to 90%.

[0022] In certain embodiments, the animal selected is a poultry, chicken, turkey, or pig.

[0023] Also provided herein is a method of stunning an animal with an exhaust gas mixture, comprising delivering an exhaust gas mixture consisting of carbon dioxide from a combustion chamber located at a processing site to a stunning chamber located at the processing site for any quantity of a selected type of animal, and contacting the selected type of animal with the exhaust gas mixture in the stunning chamber to stunning the selected type of animal.

[0024] In certain embodiments, the method further includes providing air to the combustion chamber.

[0025] In certain embodiments, the method further includes providing natural gas to the combustion chamber or providing propane in place of the natural gas to the combustion chamber.

[0026] In certain embodiments, the method further includes providing air and natural gas from a process site to the combustion chamber.

[0027] In certain embodiments, the exhaust gas mixture further comprises nitrogen and oxygen.

[0028] In certain embodiments, the method further includes cooling the exhaust gas mixture prior to delivering the exhaust gas mixture to the stunning chamber.

[0029] In certain embodiments, the method further includes filtering particulate matter from the exhaust gas mixture prior to delivering the exhaust gas mixture to the stunning chamber.

[0030] In certain embodiments, the method further includes contacting a boiler with the exhaust gas mixture from the combustion chamber to provide steam.

[0031] In certain embodiments, the method further includes combining gaseous oxygen, air, and natural gas or propane into a combustion mixture upstream of the combustion chamber, and providing the combustion mixture to be combusted in the combustion chamber to provide an exhaust gas mixture.

[0032] In certain embodiments, the percentage of carbon dioxide in the exhaust gas mixture is in the range of 11% to 90%.

[0033] In a particular embodiment, the type of animal selected is poultry.

[0034] Also provided herein is an exhaust gas mixture for stunning animals, comprising a mixture of gases for combusting at a processing site to produce an exhaust gas mixture comprising carbon dioxide for stunning animals at the processing site.

[0035] In certain embodiments of the exhaust gas mixture, the animal is a poultry, chicken, turkey, or pig.

[0036] In certain embodiments, the exhaust gas mixture further comprises nitrogen and oxygen.

[0037] In certain embodiments of the exhaust gas mixture, the percentage of carbon dioxide in the exhaust gas mixture is in the range of 11% to 90%.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, reference should be made to the following detailed description of the inventive embodiments which should be read in conjunction with the drawings, in which: [Brief description of the drawings]

[0039] [Figure 1]FIG. 1 shows a known stunning system for poultry and a bulk liquid product tank for use in the stunning system. [Diagram 2] 1 shows a stunning system and associated method according to an inventive embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Detailed Description Before describing inventive embodiments in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of parts illustrated in the accompanying drawings, because the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.

[0041] In the following description, terms such as horizontal, upright, vertical, top, bottom, lower, etc. are used only for the purpose of clarifying the present invention and should not be construed as limiting words. The drawings are intended to illustrate certain embodiments of the invention examples and are not to scale.

[0042] Referring generally to Figure 2, a food processor has a processing site 10, i.e., a plant or facility in which an embodiment of an apparatus 12 and method for stunning, for example, poultry 14, is located. The site 10 functions as follows for use as, for example, a poultry processing plant. Within the plant, poultry 14 may be, for example, chickens, turkeys, or other poultry, and such animals must be stunned within the plant before being further processed for slaughter. Stunning of other types of animals is also possible, for example pigs for producing pork products.

[0043] Typically, a mixture of pure oxygen (O2), natural gas (NG) or propane, and air depending on the application, is fed to, for example, an oxy-fuel burner or an air-oxy-fuel burner ("burner"). NG, or propane if used, is already available on-site at the plant, as the plant uses NG (or propane) for other plant operations, including providing heat to the plant and a boiler to generate steam for the slaughter of the poultry. The burner fires and heats the combustion chamber. During the combustion process, carbon dioxide (CO2), nitrogen (N2), and oxygen (O2) are produced in addition to heat and water steam. This mixture is the fuel gas or exhaust gas from the combustion and is used as the stunning gas mixture for the poultry 14.

[0044] The exhaust gas, for example, may be cooled before being used as a stunning gas mixture, after which some of the water vapor in the fuel gas must be removed or expelled therefrom before the stunning gas is introduced into the stunning process.

[0045] Thus, a steam boiler is included in the apparatus to remove heat from the exhaust gases. The steam boiler receives the exhaust gases and includes a heat exchanger through which water flows and is heated by the exhaust gases. The water in the heat exchanger is heated, thereby producing condensate and steam for use elsewhere in the process plant or at a remote location.

[0046] The steam can also be used to power turbines (not shown) which generate electricity for use in the plant and stunning equipment and process. The heat can also be dissipated into the atmosphere by connecting a circulation loop to a cooling tower or to a fresh water source (e.g. from a river). Once most of the heat has been rejected from the exhaust gases, they can be further cooled by a condenser to condense or dry the excess water vapor therefrom, and the exhaust gases are then used in the stunning process.

[0047] As previously mentioned, the stunning process requires a mixture of CO2, nitrogen, and oxygen. According to embodiments of the present application, the intake oxygen:air ratio of the combustion gases can be varied to allow greater or lesser amounts of each of CO2, nitrogen, and oxygen to be present in the exhaust gas mixture used in embodiments of the stunning device and method.

[0048] More specifically, with reference to FIG. 2, there are multiple stages I-VI that can be utilized in embodiments of the present application. These stages are described for ease of understanding of the orderly detailing and the elements within the stages and the associated interactions of these elements for stunning apparatus and method embodiments. The detailing of the stages is not intended to describe or limit the priority for performing these stages and their elements. Stages I-VI of the apparatus 12 and associated method embodiments are all located in a processing site 10 that performs the stunning of poultry 14. Stages I-VI and associated components and steps therein may be described herein as being upstream or downstream with respect to one another.

[0049] Stage I includes a bulk storage tank 16 for holding liquid oxygen (LOX). The tank 16 is pressurized to force the LOX from an outlet near the lower region of the tank to a pipeline 16' connected to the inlet of a vaporizer 17. The LOX is converted to the gas phase, i.e., vaporized, in the vaporizer 17 and then delivered as gaseous oxygen from the outlet of the vaporizer to a pipe 18 connected to the inlet of a fluid mixer 20 (also called a mixing or flow skid 20 in the food processing and industrial gas industry). Air 22 is also available for delivery in a pipe 24 connected to the inlet of the skid 20. Natural gas (NG) 26, or alternatively propane, is supplied from a location 28 in the processing site 10 and delivered through a pipe 30 to the inlet of the skid 20. In fact, all of the gases or ingredients required to provide the resulting stunning gas mixture are obtained from the processing site 10. The flow skid 20 meters or apportions selected amounts of each of the oxygen, air, and NG gas streams to the combustion stage of the inventive embodiment.

[0050] Stage II includes a flow skid 20, where the respective ratios or concentrations of gaseous O2, air, and NG introduced into the skid are rationed and injected for subsequent heating and combustion. The oxygen warms while passing through the vaporizer 17 and begins to expand into a gaseous phase. The combustion mixture from the exit of the skid 20 is delivered by a tube 32 to a burner 34, such as an oxygen-fuel burner or an air-oxygen-fuel burner, in a combustion chamber 36 in a furnace installed in the processing site 10. Alternatively, the apparatus 12 can include multiple tubes 32, one tube each for gaseous oxygen, air, and NG, which are delivered to the burner 34 where the gases are mixed for combustion. Combustion of the gaseous mixture in the chamber 36 provides a heated exhaust gas mixture 38 of CO2, N2, O2, and H2O. The heated exhaust gas mixture 38 can be further conditioned or treated to provide an exhaust gas mixture that can be used to stunning the poultry 14, without having to rely on a separate CO2 delivery, whether bulk or otherwise, from a remote location for the stunning process of the poultry 14.

[0051] Stage II includes a steam boiler 40 in contact with the exhaust gas mixture 38 from the combustion chamber 36 where water (H2O) 42 introduced into the boiler 40 produces streams of steam 44 and condensate 46. Alternative cooling of the exhaust gas mixture 38 in stage III may include a closed loop 48 for the exhaust gas mixture through a cooling tower 50 or other type of heat exchanger.

[0052] Stage IV includes optional use for the exhaust gas mixture 38 depending on the requirements of the stunning system. The exhaust gas mixture 38 is dried in a condenser 52 and H2O from the exhaust gas mixture can be removed through a condensate line 54. A filter 56 located downstream of the condenser 52 is used to remove any contaminants and / or particulate matter from the exhaust gas mixture 38 before it contacts the poultry 14.

[0053] Stage V includes a compressor 58 or blower, which pressurizes the exhaust gas mixture 38 and forces it into stage VI.

[0054] Stage VI includes a stunning chamber 60 where the exhaust gas mixture 38, with the moisture content reduced therein, is introduced to contact and stunning the poultry 14. The mixture includes CO2, N2, and O2 in respective proportions. The outlet of the compressor 58 may be connected to the inlet to the stunning chamber 60 by a pipeline 62 or conduit having an internal diameter smaller than the internal volume of the compressor.

[0055] Stage I is upstream of stage II, which is upstream of stage III, which is upstream of stage V, which is upstream of stage VI. If stage IV is used, then stage IV is located between stages III and V, i.e., stage IV is downstream of stage III and upstream of stage V. However, it is not necessary for an inventive embodiment to use the components and steps of stage IV.

[0056] Example I. Using the apparatus 12 of an embodiment of the present application, mixing 90% oxygen and 10% air with natural gas in stages I and II produces an exhaust gas mixture 38 of 53% CO2, 5% O2, 42% N2 for stunning poultry 14.

[0057] Example II. Using the apparatus 12 of the present application, mixing only 100% oxygen with natural gas (NG) in stages I and II produces an exhaust gas mixture 38 of 90% CO2, 9% O2, 1% N2 for stunning poultry 14.

[0058] The percentage of carbon dioxide in the exhaust gas mixture can be in the range of 11% to 90%, and in certain apparatus and method embodiments, the percentage of carbon dioxide in the exhaust gas mixture can be in the range of 11% to 99%.

[0059] Still referring to FIG. 2, other apparatus and method embodiments may include a pipeline 41 interconnecting the downstream region of the boiler 40 with the combustion chamber 36 to provide a cooling fluid for cooling the combustion chamber, the cooling occurring inside the chamber and / or on the exterior sidewalls of the combustion chamber. Another heat exchanger 63, for example an air-cooled heat exchanger, may also be positioned between the compressor 58 and the stunning chamber 60 in fluid communication with the exhaust gas mixture 38, thereby cooling and lowering the temperature of the mixture before it is introduced into the stunning chamber. In yet another embodiment, the compressor 58 is instead positioned downstream of the boiler 40 and upstream of the condenser / dryer 52.

[0060] Embodiments of the present apparatus and methods allow the processor to precisely adjust the ratio of intake gases to meet the requirements of a particular stunning process for a particular animal. The only bulk delivery required with embodiments of the present application is a single bulk liquid oxygen supply, eliminating the need for multiple bulk storage tanks at the site 10.

[0061] Advantages of embodiments of the present application include elimination of the inconvenience and risk of CO2 supply interruptions, providing an on-demand CO2 supply for stunning at the processing site 10, the ability to produce selected mixtures of CO2, O2, and N2 for stunning by varying the oxygen and air intake ratio, and providing a heat source for the processing facility from the exhaust gas mixture 38.

[0062] It is understood that the embodiments described herein are merely examples, and that those skilled in the art may make modifications and improvements without departing from the spirit and scope of the present invention. Such modifications and improvements are intended to be included within the scope of the present invention as set forth above and as claimed in the following claims. Moreover, not all disclosed embodiments are necessarily inclusive of alternatives, since various embodiments may be combined to provide the desired result.

Claims

1. 1. An apparatus for stunning animals with an exhaust gas mixture, comprising: a stunning chamber located at the processing site, the stunning chamber containing an equal number of animals selected for stunning; a combustion chamber located at said processing site for combusting a mixture of gases to provide therefrom an exhaust gas mixture including carbon dioxide for stunning said animal in said stunning chamber; An apparatus comprising:

2. 10. The apparatus of claim 1, further comprising a flow skid at the processing site upstream of the combustion chamber and in fluid communication with the combustion chamber for receiving gaseous oxygen, air, and natural gas or propane and providing a proportion of each of the gaseous oxygen, air, and natural gas or propane for a combustion mixture to be provided to the combustion chamber.

3. 3. The apparatus of claim 2, further comprising a heat exchanger located at the processing site downstream of the combustion chamber for receiving the exhaust gas mixture and cooling the exhaust gas mixture before it is delivered to the stunning chamber.

4. a condenser located at the processing site downstream of and in fluid communication with the heat exchanger for receiving and drying the exhaust gas mixture; 4. The apparatus of claim 3, further comprising a filter downstream of the condenser, in fluid communication with the condenser, receiving the dry exhaust gas mixture, and located at the processing site for removing particulate matter from the dry exhaust gas mixture.

5. 4. The apparatus of claim 3, further comprising a compressor or blower located at the processing site downstream of the heat exchanger, in fluid communication with the heat exchanger, and receiving the exhaust gas mixture for delivery to a stunning chamber.

6. The apparatus of claim 1 , wherein the exhaust gas mixture further comprises nitrogen and oxygen.

7. 3. The apparatus of claim 2, wherein the gaseous oxygen, the air, the natural gas, and the propane are available from the processing site.

8. The apparatus of claim 1 , wherein the combustion chamber further comprises a burner selected from the group consisting of an oxy-fuel burner and an air-oxy-fuel burner for combusting the mixture of gases.

9. a boiler located at the processing site into which the exhaust gas mixture from the combustion chamber contacts; a heat exchanger located at the processing site that receives at least a portion of the exhaust gas mixture, the heat exchanger constructed and arranged to return a cooled exhaust gas mixture for delivery to the stunning chamber; The apparatus of claim 1 further comprising:

10. The apparatus of claim 9 , wherein the heat exchanger comprises a cooling tower.

11. 10. The apparatus of claim 9, further comprising a pipeline constructed and arranged to provide the exhaust gas mixture from a downstream region of the boiler to the combustion chamber to cool the combustion chamber.

12. The apparatus of claim 1 , wherein the percentage of carbon dioxide in the exhaust gas mixture is in the range of 11% to 99%.

13. The apparatus of claim 1 , wherein the animal is selected from the group consisting of poultry, chickens, turkeys, or pigs.

14. 1. A method for stunning an animal with an exhaust gas mixture comprising the steps of: delivering an exhaust gas mixture comprising carbon dioxide from a combustion chamber located at a processing site to a stunning chamber located at said processing site for any quantity of a selected type of animal; contacting the selected type of animal with the exhaust gas mixture in the stunning chamber to stunning the selected type of animal; The method includes:

15. The method of claim 14 further comprising providing air to the combustion chamber.

16. The method of claim 14 further comprising providing natural gas to the combustion chamber.

17. The method of claim 14 further comprising providing propane to the combustion chamber.

18. The method of claim 14 further comprising providing air and natural gas from the processing site to the combustion chamber.

19. The method of claim 14 further comprising providing air and propane from the processing site to the combustion chamber.

20. The method of claim 14 , wherein the exhaust gas mixture further comprises nitrogen and oxygen.

21. 15. The method of claim 14, further comprising cooling the exhaust gas mixture prior to delivering the exhaust gas mixture to the stunning chamber.

22. 15. The method of claim 14, further comprising filtering particulate matter from the exhaust gas mixture prior to delivering the exhaust gas mixture to the stunning chamber.

23. The method of claim 14 further comprising contacting a boiler with the exhaust gas mixture from the combustion chamber to provide steam.

24. 24. The method of claim 23, further comprising providing a portion of the exhaust gas mixture from a region downstream of the boiler to the combustion chamber to cool the combustion chamber.

25. combining gaseous oxygen, air, and natural gas into a combustion mixture upstream of said combustion chamber; providing the combustion mixture to be combusted in the combustion chamber to provide the exhaust gas mixture; The method of claim 14 further comprising:

26. combining gaseous oxygen, air, and propane into a combustion mixture upstream of the combustion chamber; providing the combustion mixture to be combusted in the combustion chamber to provide the exhaust gas mixture; The method of claim 14 further comprising:

27. The method of claim 14, wherein the percentage of carbon dioxide in the exhaust gas mixture is in the range of 11% to 99%.

28. 15. The method of claim 14, wherein the selected type of animal is poultry.

29. 15. The method of claim 14, wherein the selected type of animal is selected from the group consisting of chickens, turkeys, and pigs.

30. 1. An exhaust gas mixture for stunning animals, comprising a mixture of gases that is combusted at a processing site to produce an exhaust gas mixture comprising carbon dioxide for stunning animals at said processing site.

31. 31. The exhaust gas mixture of claim 30, wherein the animal comprises poultry.

32. 31. The exhaust gas mixture of claim 30, wherein the selected type of animal is selected from the group consisting of chickens, turkeys, and pigs.

33. 31. The exhaust gas mixture of claim 30, wherein the mixture of gases includes gaseous oxygen, air, and natural gas or propane for combustion at the process site.

34. 31. The exhaust gas mixture of claim 30, wherein the exhaust gas mixture further comprises nitrogen and oxygen.

35. 31. The exhaust gas mixture of claim 30, wherein the temperature of the exhaust gas mixture is reduced prior to the stunning of an animal.

36. 31. The exhaust gas mixture of claim 30, wherein the percentage of carbon dioxide in the exhaust gas mixture is in the range of 11% to 99%.

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