WO2018209426A1

WO2018209426A1 - Air heating systems and methods using heat generated by an internal combustion engine

Info

Publication number: WO2018209426A1
Application number: PCT/CA2018/050272
Authority: WO
Inventors: Brian Arthur TIEDEMANN; Mark Peter MALEKOFF
Original assignee: Thermal Intelligence Inc.
Priority date: 2017-05-16
Filing date: 2018-03-07
Publication date: 2018-11-22

Abstract

Systems and methods for heating air using heat generated by operation of an internal combustion engine involve flowing air in an air duct past the engine to create a heated air flow, flowing exhaust gas in an exhaust gas duct through a catalytic converter to create an cleaned exhaust gas flow, and allowing the heated air flow and the cleaned exhaust gas flow to mix together to create a heated mixed gas flow within the air duct, before being discharged through an air duct outlet. Gas moving means such as fans or positive displacement blowers move air through the air duct and the exhaust gas through the exhaust duct.

Description

AIR HEATING SYSTEMS AND METHODS USING HEAT GENERATED BY AN INTERNAL COMBUSTION ENGINE

CROSS REFERENCE TO RELATED APPLICATIONS:

This application claims priority of United States Provisional Patent

Application Serial No. 62/507,1 1 1 , entitled "Air Heating Systems and Methods Using Heat Generated by an Internal Combustion Engine", filed May 16, 2017, and hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD OF THE INVENTION The present invention relates to air heating systems and methods, and more particularly to air heating systems using an internal combustion engine as a heat source.

BACKGROUND OF THE INVENTION

Temporary heating systems are used in a variety of industrial applications. As non-limiting examples, temporary heating systems may be used to thaw or de-ice equipment used in oil and gas extraction, and to heat and dehumidify buildings under construction.

The prior art includes a variety of heating systems using an internal combustion engine as a heat source: U.S. Patent Application Publication No. 2010/0326076 (Ast et al.); U.S. Patent Application Publication No. 2014/0338313 (Wollants et al.); U.S. Patent No. 4,291 ,834 (Palazzetti et al.); U.S. Patent No. 4,393,656 (Anderson et al.); U.S. Patent No. 5,535,944 (Knowles); U.S. Patent No. 6,318,077 (Claypole et al.); U.S. Patent No. 6,571 ,552 (Ban et al.); and European Patent Application Publication No. 2,910,762 (Yamanaka et al.).

U.S. Patent No. 4,291 ,834 (Palazzetti et al.) discloses a first embodiment of an air heating system that includes a duct housing and an air- cooled internal combustion engine, which drives a fan to cause air to be drawn in through an inlet mouth of the duct and blown through the duct to a utilizer (e.g., a region or space to be heated, or the interior of a drying apparatus or machine). The exhaust gases from the engine are fed as a heating fluid to a heat exchanger to heat air passing through the duct. A discharge tube conveys exhaust gases out from the heat exchanger to the exterior of the duct, and into the atmosphere. In a second embodiment of the air heating system, air that is discharged from the utilizer is mixed with exhaust gas from the engine. The resulting mixture enters a discharge duct through a discharge tube, passes through a second heat exchanger to pre- heat air entering into the system, and then discharges to the atmosphere.

Engine exhaust gas is estimated to account for approximately 22 percent of the energy of the fuel combusted by a typical internal combustion engine. Use of heat exchangers to capture heat from exhaust gas may create sufficient back pressure on the engine exhaust system to result in engine shutdown. This "cold stacking" phenomenon practically limits the amount of heat that can be recovered from the engine exhaust gas. It also known to use the kinetic energy of an internal combustion engine to drive secondary heating devices (e.g., devices that operate accordingly to principles of electrical resistive heating, magnetic induction heating, or fluid shear) to provide additional heat. However, such secondary heating devices may increase complexity and cost of the system, and fire risk.

SUMMARY OF THE INVENTION An object of the invention is to efficiently heat air using heat recovered from the operation of an internal combustion engine, including heat in exhaust gas generated by the engine. A further object of the invention is to provide heated air that is of breathable quality. Still a further object of the invention is to reduce environmental impacts of the exhaust gas. In one aspect, the present invention comprises an air heating system using heat generated by operation of an internal combustion engine comprising an engine exhaust outlet. The system comprises an air duct, an exhaust duct, at least one catalytic converter, and a first gas moving means. The air duct defines an air duct interior extending from an air duct inlet to an air duct outlet. The air duct interior is sized and shaped to at least partially contain the engine and allow through flow of air in contact with the engine when contained therein. The exhaust duct defines an exhaust duct interior extending from an exhaust duct inlet for sealed gaseous communication from the engine exhaust outlet to an exhaust duct outlet in gaseous communication with the air duct interior. The at least one catalytic converter is disposed in the exhaust duct interior for reducing a concentration of at least one undesired component of the exhaust gas passing through the exhaust duct interior before being discharged to the air duct interior. The first gas moving means comprises one or a combination of a first fan or a first positive displacement motor for moving gas through the air duct interior from the air duct inlet to the air duct outlet.

In embodiments of the system, the exhaust duct is disposed within the air duct interior.

In embodiments of the system, the system may further comprise a manifold that divides the air duct interior into an air duct interior upstream portion comprising the air duct inlet and an air duct interior downstream portion comprising the air duct outlet. The manifold collects exhaust gas exiting the exhaust duct outlet and air exiting the air duct interior upstream portion for mixing in the air duct interior downstream portion.

In embodiments of the system, the first gas moving means is disposed within the air duct interior. The first gas moving means may be powered by the engine. The system may further comprise a first variable frequency drive mechanism for varying an operating speed of the first gas moving means, and thereby vary a flow rate at which the first gas moving means moves gas through the air duct interior from the air duct inlet to the air duct outlet.

In embodiments of the system, the system further comprises a second gas moving means comprising one or a combination of a second fan or a second positive displacement motor for moving the exhaust gas through the exhaust duct interior from the exhaust duct inlet to the exhaust duct outlet. The second gas moving means may be disposed within the exhaust duct interior. The second gas moving means may be disposed between the at least one catalytic converter and the exhaust duct outlet. The second gas moving means may be powered by the engine. The system may further comprise a second variable frequency drive mechanism for varying an operating speed of the second gas moving means, and thereby varying a rate at which the second gas moving means moves the exhaust gas through the exhaust duct interior from the exhaust duct inlet to the exhaust duct outlet.

In embodiments of the system, the least one catalytic converter comprises a plurality of catalytic converters.

In embodiments of the system, the system further comprises at least one concentration sensor for measuring the concentration of the at least one undesired component of the exhaust gas in the exhaust gas after passing through the at least one catalytic converter. The system may further comprise a computer processor operatively connected to the concentration sensor and a non-transitory medium storing instruction readable by the processor to either store or output, or both store and output the concentration of the at least one undesired component of the exhaust gas measured by the concentration sensor.

In embodiments of the system, the system further comprises a bypass duct and a valve. The bypass duct defines a bypass duct interior extending from a bypass duct inlet for sealed gaseous communication from the engine exhaust outlet to a bypass duct outlet disposed outside the air duct interior. The valve selectively apportions gas exiting from the engine exhaust outlet between the exhaust duct interior and the bypass duct interior. In embodiments of the system, the system further comprises a temperature sensor for measuring a temperature of the exhaust gas. The system may further comprise a computer processor operatively connected to the temperature sensor and a non-transitory medium storing instruction readable by the processor to actuate the valve based on the temperature of the exhaust gas measured by the temperature sensor.

In embodiments of the system, the system further comprises a secondary heater positioned in the air duct interior that can provide further heat for heating air flow and/or exhaust. The secondary heater may also be powered by the engine.

In another aspect, the present invention comprises a method for heating air using heat generated by operation of an internal combustion engine. The method comprises the steps of:

(a) creating a heated air flow by flowing air past the engine to heat air with radiant heat energy generated by operation of the engine;

(b) preventing mixing of the heated air flow and exhaust gas generated by operation of the engine;

(c) creating a cleaned exhaust gas flow by flowing exhaust gas generated by operation of the engine through at least one catalytic converter to reduce a concentration of at least one undesired component of the exhaust gas; and (d) creating a heated mixed gas flow by allowing the heated air flow and the cleaned exhaust gas flow to mix together.

In embodiments of the method, the cleaned exhaust gas flow is created within the air flow. In embodiments of the method, allowing the heated air flow and the cleaned exhaust gas flow to mix together comprises flowing the heated air flow and the cleaned exhaust gas flow through a manifold.

In embodiments of the method, flowing air past the engine comprises operating a first gas moving means comprising a first fan or a first positive displacement motor.

In embodiments of the method, the first gas moving means is powered by the engine.

In embodiments of the method, operating the first gas moving means comprises varying an operating speed of the first gas moving means to vary a flow rate of air past the engine.

In embodiments of the method, flowing exhaust gas generated by operation of the engine through at least one catalytic converter comprises operating a second gas moving means comprising one or a combination of a second fan or a second positive displacement motor. The second gas moving means may be powered by the engine.

In embodiments of the method, operating the second gas moving means comprises varying an operating speed of the second gas moving means to vary a flow rate of exhaust gas through the at least one catalytic converter.

In embodiments of the method, the method further comprises measuring a concentration of the at least one undesired component of the exhaust gas after passing through the at least one catalytic converter. In embodiments of the method, the method further comprises using a computer processor and a non-transitory medium storing instruction readable by the computer processor to either store or output, or both store and output the measured concentration of the at least one undesired component of the exhaust gas.

In embodiments of the method, the method further comprises actuating a valve to vary a flow rate of exhaust gas through the at least one catalytic converter. Actuating the valve may be based on a temperature of the exhaust gas. In embodiments of the method, the method further comprises actuating a secondary heater to provide additional heat to the heated mixed gas flow. If the secondary heater is selectively variable, the secondary heater can be actuated to control the temperature of the heated air.

BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the present invention are described with reference to the following drawings. In the drawings, like elements are assigned like reference numerals. The drawings are not necessarily to scale, with the emphasis instead placed upon the principles of the present invention. Additionally, each of the embodiments depicted is but one of a number of possible arrangements utilizing the fundamental concepts of the present invention. The drawings are briefly described as follows:

Fig. 1 shows a side sectional view an embodiment of a heating system of the present invention; and

Fig. 2 shows an enlarged side section view of portion "A" of Fig. 1 .

DETAILED DESCRIPTION OF THE INVENTION

Any term or expression not expressly defined herein shall have its commonly accepted definition understood by a person skilled in the art. System overview. Figure 1 shows an exemplary embodiment of an air heating system (10) of the present invention that uses heat generated by operation of an internal combustion engine (200). The engine (200) has an engine exhaust outlet (202) and an engine air inlet (204). The engine (200) may serve other purposes such as being a source of kinetic energy to drive the movement of associated equipment (not shown). The engine (200) can use any suitable fuel combustible fuel type, such as diesel, natural gas, gasoline, jet fuel, kerosene, etc. It will be understood that present invention is not limited by the particular application of the engine (200) or its fuel type. In the exemplary embodiment, the system (10) includes an air duct (20), a manifold (30), an exhaust duct (40), at least one catalytic converter (60), a first gas moving means (80), a second gas moving means (100), a concentration sensor (120), a bypass duct (160), a secondary heater (170), a temperature sensor (180), a computer (190), and other components, as will be further described below.

Air duct. The air duct (20) directs a flow of air past at least part of the engine so that the air flow can be heated by radiant heat energy generated by the engine (200). In the exemplary embodiment shown in Figure 1 , the air duct (20) is an elongate tube-like member defining an air duct interior (22) extending from an air duct inlet (24) to an air duct outlet (26). In the exemplary embodiment of Figure 1 , the air duct interior (22) is sized and shaped to contain the entire engine (200) and allow through flow of air in contact with the engine (200). In other embodiments, the air duct interior (22) may contain only part of the engine (200), so long as air passing through the air duct interior (22) is able to come into contact with the engine (200). The air duct (20) may be made of any suitable material known in the art such as metal. Preferably, the material of the air duct (20) has a low thermal conductivity to limit the amount of heat conducted from the air duct interior (22) to the exterior of the air duct (20).

Exhaust duct. The exhaust duct (40) directs a flow of exhaust gas generated by the engine (200) through the at least one catalytic converter (60). In the exemplary embodiment shown in Figure 1 , the exhaust duct (40) is an elongate tube-like member defining an exhaust duct interior (42) extending from an exhaust duct inlet (44) to an exhaust gas outlet (46). The exhaust duct inlet (44) is in sealed gaseous communication with the engine exhaust outlet (46) to prevent mixing of air within the air duct (20) with the exhaust gas generated by the engine (200), prior to the exhaust gas passing through the at least one catalytic converter (60). The exhaust duct outlet (46) is in gaseous communication with the air duct interior (22). In the exemplary embodiment shown in Figure 1 , the exhaust duct (40) is entirely disposed within the air duct interior (22), such that any heat of exhaust gas flowing through the exhaust duct (40) is radiated into the air duct interior (22) to heat the air flowing through the air duct interior (22). In other embodiments (not shown), the exhaust duct (40) may be wholly or partially outside of the air duct interior (22), so long as the exhaust duct outlet (46) is in gaseous communication with the air duct interior (22).

Manifold. In the exemplary embodiment shown in Figure 1 , the manifold (30) is disposed within the air duct interior (22) so as to divide the air duct interior (22) into an air duct interior upstream portion (22a) comprising the air duct inlet (24), and an air duct interior downstream portion (22b) comprising the air duct outlet (26). The manifold (30) defines a manifold first opening (32) that allows gas communication between the air duct interior upstream portion (22a) and the air duct interior downstream portion (22b). The manifold (30) further defines a manifold second opening (34) that allows gas communication between the exhaust duct outlet (44) and the air duct interior downstream portion (22b). The manifold (30) thereby limits mixing of air flowing through the air duct interior (22) and exhaust gas exiting the exhaust duct outlet (46) to the air duct downstream portion (22b). In this manner, the quality of air that drawn into the engine (200) via the engine air inlet (204) is not compromised in terms of composition or temperature by the exhaust gas that exits the exhaust duct outlet (46).

Catalytic converter. The at least one catalytic converter (60) is disposed within the exhaust duct interior (42) to reduce a concentration of at least one undesired component of the exhaust gas passing through the exhaust duct interior (42) before being discharged to the air duct interior (22). Catalytic converters and their principle of operation are well known to those skilled in the art, and do not in isolation, constitute the present invention. In the exemplary embodiment shown in Figure 2, the at least one catalytic converter (60) may include a plurality of catalytic converters (60a, b, c, d) for reducing the concentration of one more undesired components of the exhaust gas. As non-limiting examples, the plurality of catalytic converters can include one or a combination of technologies including diesel oxidation catalysts, catalyzed soot filters, selective catalytic reduction, selective catalytic reduction on filter, lean nitrogen oxide (NOx) trap, ammonia oxidation catalyst, natural gas catalysts, and lean gasoline direct injection (GDI) catalysts. For example, a combination of catalyst technologies may be selected such that the cleaned exhaust gas meets U.S. Occupational Health and Safety Administration (OSHA) and U.S. National Institute for Occupational Safety and Health (NIOSH) breathable air standards, for a minimum 2,000 hour run time. For example, the at least one catalytic converter (60) may be selected so that cleaned exhaust gas has an oxygen content of between about 19 to 25 percent, a hydrocarbon content less than about 25 ppm, a carbon monoxide concentration less than about 25 ppm or 50 ppm, and a carbon dioxide level less than about 1 ,000 ppm. The selection of appropriate catalytic converter technology depending on factors such as the type of fuel combusted by the engine (200), the operating characteristics of the engine (200) to achieve a desired quality of the cleaned exhaust gas is within the knowledge of the person of ordinary skill in the art.

First and second gas moving means. The first gas moving means (80) creates a gas pressure differential between the air duct inlet (24) and the air duct outlet (26) to move gas through the air duct interior (22) from the air duct inlet (24) to the air duct outlet (26).

The second gas moving means (100) creates an exhaust gas pressure differential between the exhaust duct inlet (44) and the exhaust duct outlet (46) to move exhaust gas through the exhaust duct interior (42) from the exhaust duct inlet (44) to the exhaust gas outlet (46). The second gas moving means (100) helps to overcome the back pressure created by the catalytic converter on the engine exhaust, so as to help avoid shut down of the engine due to "cold stacking" phenomenon. However, it will be understood that the second gas moving means (100) may not be needed, depending on factors such as the pressure of the exhaust gas at the engine exhaust outlet (202), the amount of resistance to flow of the exhaust gas created by the at least one catalytic converter (60), and the gas pressure differential created by the first gas moving means (80). In the exemplary embodiment shown in Figure 1 , each of the first gas moving means (80) and the second gas moving means (100) is a fan, and more particular, an axial flow fan. In other embodiments (not shown), the first and second gas moving means (80, 100) may be another type of fan (e.g., a centrifugal fan, or cross-flow fan), or be a positive displacement blower, or a combination of a fan and a positive displacement blower.

In the exemplary embodiment shown in Figure 1 , the first gas moving means (80) is positioned inside the air duct interior (22) and proximal to the air duct outlet (26) so as to suction gas from air duct inlet (24) towards the air duct outlet (26). In other embodiments (not shown), the first gas moving means (80) may be disposed inside or outside of the air duct interior (22), and may be positioned relatively downstream or upstream of the air duct inlet (24) or the air duct outlet (26), so long as the first gas moving means (80) creates a gas pressure differential to move air through the air duct interior (22) from the air duct inlet (24) towards the air duct outlet (26).

In the exemplary embodiment shown in Figure 1 , the second gas moving means (100) is positioned with the exhaust duct interior (42) and proximal to the exhaust duct outlet (46) so as to suction gas from exhaust duct inlet (44) through the at least one catalytic converter towards the exhaust gas outlet (46). In other embodiments (not shown), the second gas moving means (100) may be disposed inside or outside of the exhaust duct interior (42), and may be positioned relatively downstream or upstream of the exhaust duct inlet (44) or the exhaust duct outlet (46), so long as the second gas moving means (80) creates a gas pressure differential to move air through the exhaust duct interior (42) from the exhaust duct inlet (44) towards the exhaust duct outlet (46).

In exemplary embodiments, each of the first and second gas moving means (80, 100) may be powered by the engine (200) (e.g., the engine (200) drives a generator (not shown) that in turn provides a source of electrical power to the first and second gas moving means (80, 100)). In other exemplary embodiments, the first and second gas moving means (80, 100) may be alternatively or additionally powered by an independent power source (e.g. , an electrochemical battery, an electric power source).

In exemplary embodiments, each of the first and second gas moving means (80, 100) is electrically powered, and is associated with a first and second variable frequency drive (VFD) (82, 102), respectively, to vary an operating speed of the first and second gas moving means (80, 100), respectively. VFDs and their principle of operation are well known to those skilled in the art, and do not in isolation, constitute the present invention. The provision of VFDs (80, 100) allows control over the flow rate of gas through the air duct interior (22) and the exhaust duct interior (42), respectively.

Concentration sensor. The concentration sensor (120) measures the concentration of the at least one undesired component of the exhaust gas in the exhaust gas after passing through the at least one catalytic converter (60). In the exemplary embodiment shown in Figure 1 , the concentration sensor (120) measures the concentration of the undesired component of the exhaust gas in the air duct interior downstream portion (22b). The concentration sensor (120) may comprise any suitable device known in the art for measuring concentration of a gas component including without limitation, electrochemical sensors and semiconductor-based sensors. Bypass duct, valve and temperature sensor. The bypass duct (160) permits exhaust gas exiting the engine exhaust outlet (202) to partly or wholly bypass the exhaust duct interior (42). The valve (168) apportions gas exiting from the engine exhaust outlet (102) between the exhaust duct interior (42) and the bypass duct interior (162). In the exemplary embodiment shown in Figure 1 , the bypass duct (160) defines a bypass duct interior (162) extending from a bypass duct inlet (164) for sealed gaseous communication from the engine exhaust outlet (102) to a bypass duct outlet (166) disposed outside the air duct interior (22). In Figure 1 , the valve (168) is shown as a butterfly valve near the junction of the exhaust duct interior (42) and the bypass duct interior (162). In other embodiments, the valve (168) may comprise any suitable type of valve mechanism known in the art.

The temperature sensor (180) measures the temperature of the exhaust gas. In the exemplary embodiment shown in Figure 1 , the temperature sensor (180) measures the temperature of the exhaust gas prior to flowing through the at least one catalytic converter.

Computer. In exemplary embodiment shown in Figure 1 , the system

(10) includes computer (190) that includes a computer processor and a non- transitory medium storing instruction readable by the processor to implement certain methods in cooperation with other operatively connected parts of the system (10) (e.g., the first and second gas moving means (80, 100) the first and second VFDs (82, 102), the concentration sensor (120), the valve (168), and the temperature sensor (180)) to transmit and receive information from them and/or to control their operation, as discussed below.

Secondary heater. In the exemplary embodiment shown in Figure 1 , the system (10) includes a secondary heater (170) positioned in the air duct interior (22). As an example, the secondary heater (170) can be positioned in the air duct interior downstream portion (22b). The secondary heater (170) is another source of heat for further heating air flow and/or cleaned exhaust gas in system (10). A secondary heater (170) can increase the temperature of the heated air provided to the space to be heated and, if the secondary heat source (170) is variable, can increase the adjustability of the temperature of the heated air discharged through air duct outlet (26). The secondary heater (170) is powered by engine (200), thereby increasing the load or torque resistance on engine (200) and, thus, increasing the efficiency of engine (200). The secondary heater (170) may comprise any suitable device known in the art for heating air or exhaust including without limitation, electrical heaters and magnetic induction heaters.

Use and operation. The use and operation of the system (10) is now be described with reference to Figure 1 , in which the arrow lines indicate the direction of gas flow. The engine (200) is activated to generate radiant heat energy, and an exhaust gas that exits the cylinder block of the engine through engine exhaust outlet (202).

The first gas moving means (80) is activated to create a flow of air through the air duct interior (22) past the engine (200). The engine (200) intakes some of the air through the engine air inlet (204) to maintain the operation of the engine (200). The remainder of the air flowing past the engine (200) is heated with the radiant heat energy generated by the engine (200) to create a heated air flow. The exhaust gas generated by operation of the engine (200) flows via the exhaust duct inlet (44) towards the exhaust duct interior (42). The sealed connection between the engine exhaust outlet (202) and the exhaust duct inlet (44) prevents mixing of the exhaust gas with the air flowing through the air duct interior upstream portion (22b). The exhaust gas that flows through the exhaust duct interior (42), flows through at least one catalytic converter (60) to reduce the concentration of at least one undesired component of the exhaust gas, and thus create a cleaned exhaust gas flow. If necessary, the second gas moving means (100) is activated to assist the flow of exhaust gas through the at least one catalytic converter (60).

The heated air flow and the cleaned exhaust gas pass through the manifold first opening (32) and the manifold second opening (34), respectively, into the air duct interior downstream portion (22b). In the air duct interior downstream portion (22b), the heated air flow and the cleaned exhaust gas flow mix together to create a mixed heated gas flow. The mixed heated gas flow is then allowed to discharge through the air duct outlet (26) to provide heated air to a space to be heated. The computer (190) may control the first and second VFD's (82, 102) to vary the operating speed of the first and second gas moving means (80, 100) respectively, in order to optimize the load on the engine (200) so that the engine works at peak efficiency, thereby minimizing contaminates in the air stream and maximizing the useful life of the engine (200). The valve (168) may be used to control the apportionment of the exhaust gas between the exhaust duct interior (42) and the bypass duct interior (162). This apportionment may be based on the temperature of the exhaust gas measured by the temperature sensor (180). For example, upon start-up of the system (10), the valve (168) may be in an initial position wherein it apportions the exhaust gas to the bypass duct interior (162), as opposed to the exhaust duct interior (42). When the temperature of the exhaust gas reaches a threshold temperature, the computer (190) may actuate the valve (168) to a second position wherein it apportions the exhaust gas to the exhaust duct interior (42), as opposed to the bypass duct interior (162). For example, it is known in the art that typical catalytic converters require exhaust gases to be at sufficiently high temperatures to efficiently convert undesirable exhaust gas components into inert ones. Thus, the threshold temperature may be selected as a temperature of the exhaust gas at which the at least one catalytic converter (60) operates at an acceptable efficacy. In this manner, the system (10) can prevent or control the amount of undesired components of exhaust gas from mixing with the heated air flow.

The concentration sensor (120) may be used to measure the concentration of the undesired component of the exhaust gas after the exhaust gas passes through the at least one catalytic converter (60). The computer (190) may monitor the concentration of the undesired component of the exhaust gas in real time, and either store or output, or both store and output the measured concentration of the at least one undesired component of the exhaust gas so as to create a data record of the concentration. Further, the computer (190) may determine whether the concentration of the undesired component of the exhaust gas exceeds a predetermined threshold level. For example, where the mixed heated gas flow is intended to be of breathable quality, the concentration sensor (120) and the computer (190) may cooperate to determine whether the concentration of carbon monoxide is below toxicity levels for workers. If upon determining that the concentration of carbon dioxide exceeds an acceptable threshold level, the computer (190) may take a related action, such as actuating the valve (168) to divert exhaust gas to the bypass duct (160) and prevent exhaust gas from entering the air duct interior downstream portion (22b). The computer (190) may also take other related actions such as de-activating or varying the speed of the first and second gas moving means (80, 100) until the concentration of carbon monoxide decreases to below the acceptable threshold level. The secondary heater (170) may be used to provide additional heat to the mixed heated gas flow to increase the temperature of the mixed heated gas flow. If the secondary heat source (170) is variable, the secondary heater can be actuated to control the temperature of the heated air discharged through air duct outlet (26).

Thus, it will be appreciated that the system (10) utilizes as much of the energy produced by the engine (200) as possible in producing heated air. By using appropriate catalytic converters, the concentration of undesired components of the exhaust gas can be controlled, to repurpose the exhaust gas as breathable quality air while also utilizing the heat of the exhaust gas, and controlling environmental impacts of the exhaust gas. Further, the kinetic energy of the engine (200) can be used to power the first and second gas moving means (80, 100), thus avoiding the need for ancillary power sources.

The present invention has been described above and shown in the drawings by way of exemplary embodiments and uses, having regard to the accompanying drawings. The exemplary embodiments and uses are intended to be illustrative of the present invention. It is not necessary for a particular feature of a particular embodiment to be used exclusively with that particular exemplary embodiment. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the exemplary embodiments, in addition to or in substitution for any of the other features of those exemplary embodiments. One exemplary embodiment's features are not mutually exclusive to another exemplary embodiment's features. Instead, the scope of this disclosure encompasses any combination of any of the features. Further, it is not necessary for all features of an exemplary embodiment to be used. Instead, any of the features described above can be used, without any other particular feature or features also being used. Accordingly, various changes and modifications can be made to the exemplary embodiments and uses without departing from the scope of the invention as defined in the claims that follow.

Claims

WE CLAIM: The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1 . An air heating system using heat generated by operation of an internal combustion engine comprising an engine exhaust outlet, the system comprising:

(a) an air duct defining an air duct interior extending from an air duct inlet to an air duct outlet, wherein the air duct interior is sized and shaped to at least partially contain the engine and allow through flow of air in contact with the engine when contained therein;

(b) an exhaust duct defining an exhaust duct interior extending from an exhaust duct inlet for sealed gaseous communication from the engine exhaust outlet to an exhaust duct outlet in gaseous communication with the air duct interior;

(c) at least one catalytic converter disposed in the exhaust duct interior for reducing a concentration of at least one undesired component of the exhaust gas passing through the exhaust duct interior before being discharged to the air duct interior; and

(d) a first gas moving means comprising one or a combination of a first fan or a first positive displacement motor for moving gas through the air duct interior from the air duct inlet to the air duct outlet.

The system of claim 1 , wherein the exhaust duct is disposed within the air duct interior.

The system of claim 2, further comprising a manifold dividing the air duct interior into an air duct interior upstream portion comprising the air duct inlet and an air duct interior downstream portion comprising the air duct outlet, wherein the manifold collects exhaust gas exiting the exhaust duct outlet and air exiting the air duct interior upstream portion for mixing in the air duct interior downstream portion.

The system of claim 1 , wherein the first gas moving means is disposed within the air duct interior.

The system of claim 1 , wherein the first gas moving means is powered by the engine.

The system of claim 1 , further comprising a first variable frequency drive mechanism for varying an operating speed of the first gas moving means, and thereby varying a flow rate at which the first gas moving means moves gas through the air duct interior from the air duct inlet to the air duct outlet.

The system of claim 1 , further comprising a second gas moving means comprising one or a combination of a second fan or a second positive displacement motor for moving the exhaust gas through the exhaust duct interior from the exhaust duct inlet to the exhaust duct outlet.

8. The system of claim 7, wherein the second gas moving means is disposed within the exhaust duct interior.

9. The system of claim 8, wherein the second gas moving means is disposed between the at least one catalytic converter and the exhaust duct outlet.

10. The system of claim 7, wherein the second gas moving means is powered by the engine.

1 1 . The system of claim 7, further comprising a second variable frequency drive mechanism for varying an operating speed of the second gas moving means, and thereby varying a rate at which the second gas moving means moves the exhaust gas through the exhaust duct interior from the exhaust duct inlet to the exhaust duct outlet.

12. The system of claim 1 , wherein the least one catalytic converter comprises a plurality of catalytic converters.

13. The system of claim 1 , further comprising at least one concentration sensor for measuring the concentration of the at least one undesired component of the exhaust gas in the exhaust gas after passing through the at least one catalytic converter.

14. The system of claim 13, further comprising a computer processor operatively connected to the concentration sensor and a non-transitory medium storing instruction readable by the processor to either store or output, or both store and output the concentration of the at least one undesired component of the exhaust gas measured by the concentration sensor.

15. The system of claim 1 , further comprising:

(a) a bypass duct defining a bypass duct interior extending from a bypass duct inlet for sealed gaseous communication from the engine exhaust outlet to a bypass duct outlet disposed outside the air duct interior; and

(b) a valve for selectively apportioning gas exiting from the engine exhaust outlet between the exhaust duct interior and the bypass duct interior.

16. The system of claim 15, further comprising a temperature sensor for measuring a temperature of the exhaust gas.

17. The system of claim 16, further comprising a computer processor operatively connected to the temperature sensor and a non-transitory medium storing instruction readable by the processor to actuate the valve based on the temperature of the exhaust gas measured by the temperature sensor.

18. The system of claim 1 , further comprising a secondary heater positioned in the air duct interior.

19. A method for heating air using heat generated by operation of an internal combustion engine, the method comprising the steps of:

(c) creating a cleaned exhaust gas flow by flowing exhaust gas generated by operation of the engine through at least one catalytic converter to reduce a concentration of at least one undesired component of the exhaust gas; and

(d) creating a heated mixed gas flow by allowing the heated air flow and the cleaned exhaust gas flow to mix together.

20. The method of claim 19, wherein the cleaned exhaust gas flow is created within the air flow.

21 . The method of claim 19, wherein allowing the heated air flow and the cleaned exhaust gas flow to mix together comprises flowing the heated air flow and the cleaned exhaust gas flow through a manifold.

22. The method of claim 19, wherein flowing air past the engine comprises operating a first gas moving means comprising a first fan or a first positive displacement motor.

23. The method of claim 22, wherein the first gas moving means is powered by the engine.

24. The method of claim 22, wherein operating the first gas moving means comprises varying an operating speed of the first gas moving means to vary a flow rate of air past the engine.

25. The method of claim 19, wherein flowing exhaust gas generated by operation of the engine through at least one catalytic converter comprises operating a second gas moving means comprising one or a combination of a second fan or a second positive displacement motor.

26. The method of claim 25, wherein the second gas moving means is powered by the engine.

27. The method of claim 25, wherein operating the second gas moving means comprises varying an operating speed of the second gas moving means to vary a flow rate of exhaust gas through the at least one catalytic converter.

28. The method of claim 25, further comprising measuring a concentration of the at least one undesired component of the exhaust gas after passing through the at least one catalytic converter.

29. The method of claim 26, further comprising using a computer processor and a non-transitory medium storing instruction readable by the computer processor to either store or output, or both store and output the measured concentration of the at least one undesired component of the exhaust gas.

30. The method of claim 19, further comprising actuating a valve to vary a flow rate of exhaust gas through the at least one catalytic converter.

31 . The method of claim 30, wherein actuating the valve is based on a temperature of the exhaust gas.

32. The method of claim 19, further comprising actuating a secondary heater to provide heat to the heated mixed gas flow.