US20160169071A1

US20160169071A1 - Combined heat and power system

Info

Publication number: US20160169071A1
Application number: US14/966,122
Authority: US
Inventors: Sridhar Deivasigamani; Sivaprasad Akasam
Original assignee: Individual
Current assignee: Intellihot Inc
Priority date: 2014-12-11
Filing date: 2015-12-11
Publication date: 2016-06-16

Abstract

A combined heat and power system comprising an electric power generator configured to receive gaseous fuel and output electricity at a voltage level to an electrical grid and hot exhaust, a heat exchanger comprising a water input line, a water output line and a heat exchanger coil connecting the water input line and the water output line, wherein the heat exchanger coil is thermally adapted to the hot exhaust and a blower configured for selectively drawing ambient air to be mixed with the hot exhaust, whereby when hot water is demanded, the blower is not enabled and when hot water is not demanded, the blower is turned on to draw ambient air that is mixed with the hot exhaust such that the temperature of the hot exhaust can be reduced.

Description

PRIORITY CLAIM AND RELATED APPLICATIONS

This non-provisional application claims the benefit of priority from provisional application U.S. Ser. No. 62/090,405 filed Dec. 11, 2014. Said application is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention
The present invention is directed generally to a combined heat and power system. More specifically, the present invention is directed to a combined heat and power system where the electric power generated in the combined heat and power system is configured to be supplied via a municipal or public electrical grid to customers of a local network.
2. Background Art
Most combined heat and power systems have been configured to receive and use gaseous fuel to generate heat and electric power. The generated electric power is used locally to power devices connected within a home or building and not any devices located at a distance on another location on a municipal or public electrical grid. The generated power must be used immediately at the locale within which the combined heat and power system is located without the benefit of storage for later use at the locale or another locale. Therefore, the amount of electric power generated is typically small, e.g., sufficient only for one or two residences and the cost for generating power becomes prohibitively high as the equipment is incapable in providing economy of scale.
Thus, there is a need for a combined heat and power system having a means for sharing its generated power with its neighbors or otherwise consumed or stored economically and thus capable of lowering the cost per unit electric power generated due to economy of scale.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a combined heat and power system including:

(a) an electric power generator configured to receive gaseous fuel and output hot exhaust and electricity at a voltage level;
(b) at least one heat exchanger including a fluid input line, a fluid output line and a heat exchanger coil connecting the fluid input line and the fluid output line and adapted to prepare a hot fluid, wherein the at least one heat exchanger is thermally adapted to the hot exhaust; and
(c) a blower configured for selectively drawing ambient air to be mixed with the hot exhaust, whereby when the hot fluid is demanded, the blower is not enabled and a fluid is drawn through the fluid input line and delivered at the fluid output line to cause heat recovery from the hot exhaust to the fluid and when the hot fluid is not demanded, the blower is turned on to draw ambient air that is mixed with the hot exhaust such that the temperature of the hot exhaust can be reduced.

In one embodiment, the fluid is water.
In one embodiment, the voltage level is disposed at a level of from about 5 V to about 30 V higher than the supply voltage of a public electrical grid such that electricity generated of the electric power generator may be transmitted via the public electrical grid.
In one embodiment, the electric power generator is a micro turbine. In another embodiment, the electric power generator is a solid oxide fuel cell.
In one embodiment, the electric power generator comprises a common exhaust conductor configured for receiving the hot exhaust.
In one embodiment, the at least one heat exchanger is adapted to receive heat from a burner and output exhaust adapted to be emptied into the common exhaust conductor.
In one embodiment, the common exhaust conductor is a plastic duct.
In one embodiment, the output of the electric power generator is functionally connected to a local network.
An object of the present combined heat and power system is to provide a combined heat and power system capable of producing heat for local consumption and electricity for local consumption and consumption of customers within a local network such that reliance of the customers of the local network on public electrical grid can be reduced or eliminated.
Another object of the present combined heat and power system is to provide a system capable of providing not only heat but also electricity.
Another object of the present combined heat and power system is to provide a system capable of utilizing waste heat from an electric power generator of the combined heat and power system in a water and/or space heating system of the combined heat and power system.
Whereas there may be many embodiments of the present invention, each embodiment may meet one or more of the foregoing recited objects in any combination. It is not intended that each embodiment will necessarily meet each objective. Thus, having broadly outlined the more important features of the present invention in order that the detailed description thereof may be better understood, and that the present contribution to the art may be better appreciated, there are, of course, additional features of the present invention that will be described herein and will form a part of the subject matter of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 is one embodiment of a combined heat and power system according to the present invention.

FIG. 2 is one embodiment of a fluid heating and space heating system configured for receiving heat from the heat recovery module of a micro turbine.

FIG. 3 is a diagram depicting a combined heat and power system being used by only one consumer.

FIG. 4 is a diagram depicting an arrangement where the electric power generated in a combined heat and power system is shared within a small network of consumers.

FIG. 5 is a diagram depicting a means by which the electric power generated in a combined heat and power system is shared within a small network of consumers.

FIG. 6 is a diagram depicting another means by which the electric power generated in a combined heat and power system is shared within a small network of consumers.

FIG. 7 is a diagram depicting an example of utilization of various components of a combined heat and power system throughout the time span of a year.

PARTS LIST

2—combined heat and power system
4—heat recovery module of an electric power generator, e.g., micro turbine
6—heat exchanger coil
8—electric power generator, e.g., micro turbine
10—hot exhaust of electric power generator, e.g., micro turbine
12—blower
14—ambient air
16—combined water and/or air heating system without burner
18—fluid heating system with burner
20—low temperature exhaust
22—common exhaust conductor
24—fluid input line
26—fluid output line
28—gas supply
30—plate-type heat exchanger
32—circulation pump
34—heat trap
36—bypass valve
38—flow sensor and control valve package
40—buffer tank
42—burner
44—supply line
46—return line
48—heat source

PARTICULAR ADVANTAGES OF THE INVENTION

The present combined heat and power system eliminates the need for discrete air and/or water heating systems and electric power generators. Combined heating systems and electric power generators enable waste heat from one system to be harnessed and utilized in another, thereby increasing the total efficiency of the combined system. In occasions where such waste heat from the hot exhaust of the power generator cannot be harnessed, the hot exhaust is diluted to yield tempered exhaust that can be carried using lower cost exhaust conductors, e.g., plastic ducts, as compared to stainless steel ducts suitable for carrying exhaust at significantly higher temperatures. As a result, equipment costs can be reduced significantly by using plastic ducts.
The present combined heat and power system supplies electric power to nearby consumers of a network of consumers via existing power lines that are shared between the homes or points of use. No additional and dedicated power lines are necessary.
The losses due to transmission of electric power over short distances, e.g., several hundred feet is much less than the losses incurred due to transmission of power over long distances, e.g., miles to hundreds of miles. Therefore, when power is supplied by a source that is located nearby, the transmission efficiency can be greatly increased.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The term “about” is used herein to mean approximately, roughly, around, or in the region of. When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 20 percent up or down (higher or lower).
FIG. 1 is one embodiment of a combined heat and power system 2 according to the present invention. In this embodiment, the combined heat and power system 2 includes an electric power generator 8, one or more combined water and air/space heating systems or water heating systems. A by-product of an electric power generator 8, hot exhaust 10 disposed at a temperature of from about 550 degrees F. to 2000 degrees F., is channeled through one or more combined water and space heating systems or one or more water heating systems. In the embodiment shown in FIG. 1, the hot exhaust generated in the electric power generator 8 is shown channeled through two combined fluid and space heating systems 16, each having a heat exchanger coil 6 configured for carrying water or another fluid, depending on the desired use of the fluid. For a residential water heating system, this fluid can be water. For a closed loop heating system, e.g., a radiant floor heating system, this fluid can be an anti-freeze substance, e.g., Propylene Glycol. Each heat exchanger coil 6 is connected to a fluid input line 24 for receiving a fluid to be heated and a fluid output line where heated fluid is sent. Each combined fluid and space heating system further includes a blower 12 configured to draw and merge ambient air 14 with the hot exhaust of the power generator such that the temperature of the hot exhaust 10 can be reduced to under about 220 degrees F. when heating is not demanded. The spent exhaust 20 from each combined fluid and space heating system is configured to empty into a common exhaust conductor 22. It can therefore be recognized that a portion of the waste heat, e.g., up to as much as about 75% of the waste heat, from an electric power generator 8 is recovered and used in fluid heating. As the exhaust from the electric power generator 8 has been tempered, the common exhaust conductor 22 can be fabricated from low temperature components, e.g., plastic, instead of costly, high temperature grade materials, e.g., stainless steel. The water output line 26 of each combined water and space heating system is supplied to meet hot water and space heating requirements. In addition, there is shown several (e.g., four) additional hot water heating systems 18, each having an independently provided heat source 48, e.g., a burner, electric heating element, etc., to supply heat to the water flow carried in its heat exchanger coil 6. The exhaust 20 from each hot water heating system 18 is also configured to empty into the common exhaust conductor 22. In the event no water and/or space heating is demanded but when the electric power generator continues to supply electricity or otherwise turned on, the blower 12 is turned on to reduce the temperature of the hot exhaust from the electric power generator 8.
In one embodiment, the electric power generator 8 is a 15 to 20 kW micro turbine. Reference is made to U.S. Pat. No. 6,198,174 entitling “Microturbine power generating system” to Nims et al. for a micro turbine suitable for use in the present combined heat and power system. According to Wikipedia website, “Micro turbines are small-in-size electricity generators that burn both gaseous and liquid fuels to create high-speed rotation, which turns an electrical generator.”
In another embodiment, the electric power generator 8 is a solid oxide fuel cell. Reference is made to U.S. Pat. No. 5,741,605 entitling “Solid oxide fuel cell generator with removable modular fuel cell stack configurations” to Gillett et al. for a solid oxide fuel cell suitable for use in the present combined heat and power system. According to Wikipedia website, “a solid oxide fuel cell (or SOFC) is an electrochemical conversion device that produces electricity directly from oxidizing a fuel. Fuel cells are characterized by their electrolyte material; the SOFC has a solid oxide or ceramic, electrolyte. Advantages of this class of fuel cells include high efficiency, long-term stability, fuel flexibility, low emissions, and relatively low cost. The largest disadvantage is the high operating temperature which results in longer start-up times and mechanical and chemical compatibility issues”
FIG. 2 is one embodiment of a fluid (e.g., water) heating and space heating system configured for receiving heat from the heat recovery module 4 of a micro turbine. Cold water is drawn through the water input line 24 and the water can receive heat through the heat exchanger coil 6 from the burner 42 and/or the plate-type heat exchanger 30 which now receives a heat input from the hot exhaust of the heat recovery module 4 of the micro turbine. Heated domestic water is delivered via the water output line 26 to customers with or without the aid of circulation pump 32. If recirculation is desired without a hot water demand, the pump 32 must be turned on to recirculate water through the plate-type heat exchanger 30 and the buffer tank 40. In one example, the supply line 44 transports a heated flow as a result of heat transfer from the hot exhaust from the heat recovery module 4 or the heat exchanger coil 6, out of the plate-type heat exchanger 30 to heat floors in radiant floor heating or baseboards and air coils in baseboard heating and returns the flow via the return line 46. Heat trap 34 prevents excessively hot fluid of the water heating system from reaching the fluid output line 26 as the fluid exiting the fluid output line 26 may come in direct contact with a human consumer. A bypass valve 36 is made available should mixing of incoming unheated fluid through the fluid input line 24 and the heated fluid through the fluid output line 26 is desired. The flow sensor and control valve package 38 provides the fluid heating and space heating system the incoming unheated flowrate, such that its control valve may be adjusted to control the flowrate of unheated flowrate into the heating system.
FIG. 3 is a diagram depicting a combined heat and power system being used by only one consumer. In addition to water and space heating, electric power is provided. If a micro turbine is used, the only supply required by the combined heat and power system is a fuel supply 28, e.g., propane, natural gas, etc. The generated electric power may be consumed entirely within a home but excess power is typically available due the amount of power generated from a power generator having capacity large enough to be economically feasible to own and operate. The excess power is configured to be put on the municipal/public electrical grid or simply public electrical grid such that it may be used by neighboring consumers. If a public electrical grid is unavailable, a private electrical grid connecting only a local network of consumers may be created. The geographical reach of a private electrical grid may range from several hundred feet to tens of thousands of feet. If a public electrical grid is available and that a local network of consumers are located in close vicinity, e.g., within distances of from several hundreds of feet to tens of thousands of feet from where the electric power is generated, the local electric power generator may serve as an electric provider to these consumers. In the event the local network of consumers are served via a public electrical grid, the voltage level of the locally generated electric power transmission is boosted by a threshold of from about 5 V to about 30 V above the voltage at which the public electrical grid is disposed and transmitted in phase with the public electrical grid. As such, the local network of consumers draw power from the local producer and not from the large-scale power providers located at great distances, e.g., miles to hundreds of miles. As transmission losses over short distances are negligible compared to transmission losses over great distances, the ability to generate and transmit power locally reduces wastes and lowers the cost of delivered power.
FIG. 4 is a diagram depicting an arrangement where the electric power generated in a combined heat and power system is shared within a small network of consumers. It shall be noted that the generated heat is consumed within the home to which the combined heat and power system is disposed. Excess electric power is put on a public electrical grid such that it can be transmitted to and consumed in neighboring homes. In one example, the amount of compensation each consumer makes to a local supplier of electric power may be based on the consumer's historical electric power usage drawn from the public electrical grid, prior to the implementation of such a local supply of electric power. The consumer may simply pay a flat fee to the local supplier.
In one embodiment, further economic benefits may be realized when each consumer participating in a lower power distribution scheme is capable of scheduling its power usage based on the most favorable energy pricing or availability of locally generated electric power at a particular time of day. For instance, if at peak power production, a total of twenty appliances, e.g., Internet of Things (commonly known as IOT) devices across the local network of consumers may be turned on at the same time due to power generating limitations of the local combined heat and power system, a request to turn on an additional appliance using the locally provided electric power may be declined. The request may be scheduled to be met at a later time when the operations of other appliances have concluded. Reference is made to Applicants' co-pending application U.S. Pat. Pub. No. 2012/0191256 entitling “Masterless control system methods for networked water heaters” for a mechanism useful for controlling appliances over a network of consumers. Appropriate parameters of the network, e.g., usage of a water heating system, may be manipulated to prevent or allow the activation of the water heating system. FIG. 5 is a diagram depicting a means by which the electric power generated in a combined heat and power system is shared within a small network of consumers. The electric power-consuming devices or appliances available in each home are functionally connected to a network, e.g., via a cloud solution, where each device is properly identified and capable to be scheduled to start functioning at any moment.
FIG. 6 is a diagram depicting another means by which the electric power generated in a combined heat and power system is shared within a small network of consumers. The potential of the combined heat and power system is raised to a value matching the level of the public electrical grid. Note that the output from the combined heat and power system is connected to a public electrical grid at a point upstream of a neighborhood transformer.
FIG. 7 is a diagram depicting an example of utilization of various components of the present combined heat and power system throughout the time span of a year. The primary home at which the combined heat and power system is disposed consumes all the heat by-product to heat water and space. The thick solid line represents the unit of energy the combined heat and power or the public electrical grid start out with. The dash line represents the energy losses due to electric transmission over great distances. The line dotted with square boxes represents energy losses due to the generation of waste heat from the electric power generator over warm months as the waste heat rejected from the electric power generator is not used in heating. It shall be noted from the diagram that even with the heat from the combined heat and power system that is not used, the amount of losses of the combined heat and power system is less than that of the grid losses as all of the heat generated as a by-product of electric power production is used during cold months. It shall be noted that the difference between the dash line and the line dotted with square boxes represents the heat generated as a by-product of electric power production that is utilized in the combined water and space heating system.
The detailed description refers to the accompanying drawings that show, by way of illustration, specific aspects and embodiments in which the present disclosed embodiments may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice aspects of the present invention. Other embodiments may be utilized, and changes may be made without departing from the scope of the disclosed embodiments. The various embodiments can be combined with one or more other embodiments to form new embodiments. The detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, with the full scope of equivalents to which they may be entitled. It will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments shown. This application is intended to cover any adaptations or variations of embodiments of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive, and that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Combinations of the above embodiments and other embodiments will be apparent to those of skill in the art upon studying the above description. The scope of the present disclosed embodiments includes any other applications in which embodiments of the above structures and fabrication methods are used. The scope of the embodiments should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

What is claimed herein is:

1. A combined heat and power system comprising:

(a) an electric power generator configured to receive gaseous fuel and output hot exhaust and electricity at a voltage level;

(b) at least one heat exchanger comprising a fluid input line, a fluid output line and a heat exchanger coil connecting said fluid input line and said fluid output line and adapted to prepare a hot fluid, wherein said at least one heat exchanger is thermally adapted to the hot exhaust; and

(c) a blower configured for selectively drawing ambient air to be mixed with the hot exhaust, whereby when the hot fluid is demanded, said blower is not enabled and a fluid is drawn through said fluid input line and delivered at said fluid output line to cause heat recovery from the hot exhaust to the fluid and when the hot fluid is not demanded, said blower is turned on to draw ambient air that is mixed with the hot exhaust such that the temperature of the hot exhaust can be reduced.

2. The combined heat and power system of claim 1, wherein said voltage level is disposed at a level of from about 5 V to about 30 V higher than the supply voltage of a public electrical grid such that electricity generated of said electric power generator may be transmitted via the public electrical grid.

3. The combined heat and power system of claim 1, wherein said electric power generator is a micro turbine.

4. The combined heat and power system of claim 1, wherein said electric power generator is a solid oxide fuel cell.

5. The combined heat and power system of claim 1, wherein said electric power generator comprises a common exhaust conductor configured for receiving the hot exhaust.

6. The combined heat and power system of claim 5, wherein said at least one heat exchanger is adapted to receive heat from a burner and output exhaust adapted to be emptied into said common exhaust conductor.

7. The combined heat and power system of claim 5, wherein said common exhaust conductor is a plastic duct.

8. The combined heat and power system of claim 1, wherein said fluid is water.

9. The combined heat and power system of claim 1, wherein the output of said electric power generator is functionally connected to a local network.

10. A combined heat and power system comprising:

(a) an electric power generator configured to receive gaseous fuel and output hot exhaust and electricity at a voltage level disposed at a level of from about 5 V to about 30 V higher than the supply voltage of a public electrical grid such that electricity generated of said electric power generator may be transmitted via the public electrical grid;

11. The combined heat and power system of claim 10, wherein said electric power generator is a device selected from the group consisting of a micro turbine and a solid oxide fuel cell.

12. The combined heat and power system of claim 10, wherein said electric power generator comprises a common exhaust conductor configured for receiving the hot exhaust.

13. The combined heat and power system of claim 12, wherein said at least one heat exchanger is adapted to receive heat from a burner and output exhaust adapted to be emptied into said common exhaust conductor.

14. The combined heat and power system of claim 12, wherein said common exhaust conductor is a plastic duct.

15. The combined heat and power system of claim 10, wherein said fluid is water.

16. A combined heat and power system comprising:

(b) at least one heat exchanger comprising a water input line, a water output line and a heat exchanger coil connecting said water input line and said water output line adapted to prepare a hot water supply, wherein said at least one heat exchanger is thermally adapted to the hot exhaust; and

(c) a blower configured for selectively drawing ambient air to be mixed with the hot exhaust, whereby when the hot water supply is demanded, said blower is not enabled and a water flow is drawn through said water input line and delivered at said water output line to cause heat recovery from the hot exhaust to the water flow and when the hot water supply is not demanded, said blower is turned on to draw ambient air that is mixed with the hot exhaust such that the temperature of the hot exhaust can be reduced.

17. The combined heat and power system of claim 16, wherein said voltage level is disposed at a level of from about 5 V to about 30 V higher than the supply voltage of a public electrical grid such that electricity generated of said electric power generator may be transmitted via the public electrical grid.

18. The combined heat and power system of claim 16, wherein said electric power generator is a device selected from the group consisting of a micro turbine and a solid oxide fuel cell.

19. The combined heat and power system of claim 16, wherein said electric power generator comprises a common exhaust conductor configured for receiving the hot exhaust.

20. The combined heat and power system of claim 19, wherein said common exhaust conductor is a plastic duct.