U.S. patent application number 13/707956 was filed with the patent office on 2013-06-13 for recovery for thermal cycles.
The applicant listed for this patent is Herman Artinian, Parsa Mirmobin, Dennis Strouse. Invention is credited to Herman Artinian, Parsa Mirmobin, Dennis Strouse.
Application Number | 20130145763 13/707956 |
Document ID | / |
Family ID | 48570765 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130145763 |
Kind Code |
A1 |
Mirmobin; Parsa ; et
al. |
June 13, 2013 |
RECOVERY FOR THERMAL CYCLES
Abstract
A gas burner system may include a first burner configured to
burn gas to produce burned gas in a first portion of the waste gas
burner system and a second burner configured to burn gas to produce
burned gas in a second portion of the waste gas burner system. A
heat exchanger may reside out of the first portion and may be
configured to receive heat from the burned gas in the second
portion and heat a working fluid of a thermal cycle system. A valve
may be configured to control an amount of gas provided to the
second burner. The gas may be a waste gas from a process. The
thermal cycle system may include an organic Rankine cycle.
Inventors: |
Mirmobin; Parsa; (La Mirada,
CA) ; Strouse; Dennis; (Anaheim, CA) ;
Artinian; Herman; (Huntington Beach, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mirmobin; Parsa
Strouse; Dennis
Artinian; Herman |
La Mirada
Anaheim
Huntington Beach |
CA
CA
CA |
US
US
US |
|
|
Family ID: |
48570765 |
Appl. No.: |
13/707956 |
Filed: |
December 7, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61569177 |
Dec 9, 2011 |
|
|
|
61569702 |
Dec 12, 2011 |
|
|
|
Current U.S.
Class: |
60/671 ;
122/7B |
Current CPC
Class: |
Y02E 20/12 20130101;
F01K 25/08 20130101; F22B 1/1892 20130101; F22B 1/18 20130101 |
Class at
Publication: |
60/671 ;
122/7.B |
International
Class: |
F22B 1/18 20060101
F22B001/18; F01K 25/08 20060101 F01K025/08 |
Claims
1. A gas burner system comprising: a first burner configured to
burn gas to produce burned gas in a first portion of the waste gas
burner system; a second burner configured to burn gas to produce
burned gas in a second portion of the waste gas burner system; a
heat exchanger residing out of the first portion, the heat
exchanger configured to receive heat from the burned gas in the
second portion and heat a working fluid of a thermal cycle system;
and a valve configured to control an amount of gas provided to the
second burner.
2. The waste gas burner system of claim 1, wherein the first
portion of the waste gas burner system is a first chamber and the
second portion of the gas burner system is a second chamber, the
first chamber separated from the second chamber by a thermal
barrier.
3. The gas burner system of claim 2, wherein the thermal barrier
comprises an insulated wall configured to keep heat generated in
the first chamber isolated from the second chamber.
4. The gas burner system of claim 2, wherein the thermal barrier
comprises an aperture configured to allow burned gas from the first
chamber to aid in exhausting burned gas from the second
chamber.
5. The gas burner system of claim 2, wherein the thermal barrier
comprises an aperture configured to prevent burned gas from the
first chamber from entering the second chamber.
6. The gas burner system of claim 1, further comprising an air fan
configured to provide air to the first chamber.
7. The gas burner system of claim 1, further comprising: an air fan
configured to provide air to both the first chamber and second
chamber; and a diverter valve configured to receive a signal from
the thermal cycle system and control an amount of air provided to
one or both of the first chamber or the second chamber.
8. The gas burner system of claim 1, further comprising: a first
air fan configured to provide air to the first chamber; and a
second air fan configured to provide air to the second chamber,
wherein the first air fan and the second air fan can each be
controlled separately by the thermal cycle system.
9. The gas burner system of claim 1, wherein the heat exchanger
resides in the second portion of the gas burner system, and wherein
the working fluid of the thermal cycle system passes through at
least a portion of the heat exchanger.
10. The gas burner system of claim 1, wherein the burned gas heats
a thermal fluid that heats the working fluid.
11. The gas burner system of claim 1, wherein the thermal cycle
system comprises an organic Rankine cycle.
12. The gas burner system of claim 1, further comprising a flue
stack configured to received burned gas from the first and second
chambers and direct the burned gas to one or both of a gas
destruction process or another process.
13. The gas burner system of claim 1, wherein the gas burner system
comprises an incinerator.
14. The gas burner system of claim 1, wherein the gas burner system
comprises a flare.
15. The gas burner system of claim 1, wherein the first burner
resides at a position above the heat exchanger and the second
burner resides at a position below the heat exchanger.
16. The gas burner system of claim 1, wherein the valve is
configured to receive gas and to control the amount of gas directed
to the second burner and to direct a remainder of the received gas
to the first burner.
17. The gas burner system of claim 16, wherein the valve is
controlled by the thermal cycle system.
18. The gas burner system of claim 1, wherein the gas comprises a
waste gas.
19. A method comprising: burning a first portion of a gas in a gas
burner device; burning a second portion of a gas in a gas burner
device; heating a thermal cycle working fluid with the burning of
the second portion of the gas; and directing the burned gas out of
the chamber.
20. The method of claim 19, wherein heating the thermal cycle
working fluid comprises heating a thermal fluid.
21. The method of claim 19, wherein directing the burned gas out of
the chamber comprises directing the burned gas to another
process.
22. The method of claim 19, wherein a heat exchanger of a thermal
cycle resides in the second portion, and the thermal cycle working
fluid is heated by the burning of the second portion of the
gas.
23. A system comprising: a gas burner device comprising: a first
burner configured to burn gas to produce burned gas in a first
portion of the gas burner device, a second burner configured to
burn gas to produce burned gas in a second portion of the gas
burner device, and a valve configured to control an amount of gas
provided to the second burner; and a thermal cycle system
comprising: a heat exchanger configured to receive heat from the
burned gas in the second portion of the gas burner device and heat
a thermal cycle working fluid, and an electric machine apparatus
configured to receive the heated working fluid and generate
electric power based on receiving the heated working fluid.
24. The system of claim 23, wherein the heat exchanger resides in
the second portion of the gas burner device and receives heat from
the burned gas in the second portion of the gas burner device, and
wherein the working fluid of the thermal cycle passes through at
least a portion of the heat exchanger.
25. The system of claim 23, wherein the first portion of the gas
burner system is a first chamber and the second portion of the gas
burner system is a second chamber, the first chamber separated from
the second chamber by a thermal barrier, wherein the thermal
barrier comprises an aperture configured to allow burned gas from
the first chamber to aid in exhausting burned gas from the second
chamber.
26. The system of claim 23, wherein the thermal cycle system
comprises an organic Rankine cycle.
27. The system of claim 23, wherein the gas comprises a waste gas.
Description
CLAIM OF PRIORITY
[0001] This application claims priority to U.S. Provisional Patent
Application having Ser. No. 61/569,177, filed Dec. 9, 2011 and U.S.
Provisional Patent Application having Ser. No. 61/569,702, filed
Dec. 12, 2011, the entire contents of the forgoing are incorporated
by reference herein.
FIELD
[0002] This disclosure pertains to heat recovery for thermal
cycles, and more particularly, to heat recovery from flares and/or
incinerators for a Rankine Cycle.
BACKGROUND
[0003] During the production of oil and gas, either in the field or
at processing plants, natural gas and/or other flammable process
gases are often consumed using a flare or incinerator. Heat may be
dissipated as a result of combustion through hot gases in the stack
vented out to the environment.
SUMMARY
[0004] This disclosure describes systems, methods, and apparatuses
whereby this heat can be safely and effectively captured without
impacting the underlying oil and gas production and used by way of
a thermal cycle to produce electric power in a safe manner, and/or
use the excess heat for other processes.
[0005] By providing a bypass some or all of the hot gas can
exchange heat with the thermal cycle heat exchanger. This allows
heat recovery without impacting the gas combustion process or burn
rate. Furthermore, a failure of the thermal cycle system does not
impact the flare gas process.
[0006] For high flow applications or applications that allow large
pressure drops across the valves, the use of butterfly valves
enables rapid equalization of pressure across the valve. Therefore,
the power required to actuate the valve is decreased, and control
of the valve is more readily established.
[0007] Control of the transfer of heat to the thermal cycle heat
exchanger is realized by controlling the exposure of heat exchanger
surface to hot gas. This method can be used alone or in conjunction
with valves and fans and by controllably changing the position of
the heat exchanger within the heating chamber. The valves and/or
the fans can be controlled by the thermal cycle system to control
the heat transferred to the working fluid.
[0008] The flue stack may be designed in such a way to allow
natural convection to exhaust the gases through the bypass.
[0009] Integrating the ORC heat exchanger within the stack allows
for more effective heat transfer, simpler plant and less
obstruction to flue gases. A heat exchanger may reside in direct
path of flue gases. In such an arrangement a fan may be used to
assist the flue gas through the heat exchanger. The ORC system
working fluid may be heated in conjunction with another process
liquid reduces overall cost and provides electric power to be used
on site or to supply to the grid. A heat source may be used to
elevate the temperature of a process fluid as well as an ORC system
fluid by means of transferring heat through the process fluid.
DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1A is a schematic diagram of an example thermal
cycle.
[0011] FIG. 1B is a schematic diagram of an example Rankine Cycle
system illustrating example Rankine Cycle system components.
[0012] FIG. 2A is a schematic illustration of an example combined
waste gas burner and thermal cycle heat exchanger.
[0013] FIG. 2B is a schematic illustration of an example combined
waste gas burner and thermal cycle heat exchanger.
[0014] FIG. 2C is a schematic illustration of an example combined
waste gas burner and thermal cycle heat exchanger.
[0015] FIG. 3 is a schematic illustration of an example waste gas
burner and heat exchanger system.
[0016] FIG. 4 is a schematic illustration of an example waste gas
burner and heat exchanger system.
[0017] FIG. 5 is a schematic illustration of an integrated spiral
heat exchanger embedded within the structure of the flue stack.
[0018] FIG. 6 is a schematic illustration of an example waste gas
burner and heat exchanger system.
[0019] FIG. 7 is a schematic of an example burner and thermal cycle
system.
[0020] FIG. 8A is a schematic illustration of an example heat
transfer system.
[0021] FIG. 8B is a schematic illustration of another example heat
transfer system.
[0022] FIG. 9A is a schematic illustration of an example dual waste
gas burner and heat exchanger system.
[0023] FIG. 9B is a schematic illustration of another example dual
waste gas burner and heat exchanger system.
[0024] FIG. 10 is a schematic illustration of an example combined
waste gas burner and thermal cycle heat exchanger system.
DETAILED DESCRIPTION
[0025] The disclosure describes arrangements for capturing waste
heat generated from a burning waste gas either in a flare burner,
or incinerator. The captured waste heat may be used as heat input
to a thermal cycle, such as a (Organic) Rankine Cycle. References
made to Rankine Cycles or Organic Rankine Cycles (ORC) are
examples. Other thermal cycles within the scope of this disclosure
include, but are not limited to, Sterling cycles, Brayton cycles,
Kalina cycles, etc. The principles of invention apply to all
thermal cycles where capturing heat from a heat source is required.
Similarly fuel used for generating heat may be waste natural gas,
or other fuel sources such as biogas, oil etc.
[0026] FIG. 1A is a schematic diagram of a an example thermal cycle
10. The cycle consists of a heat source 12 and a heat sink 14. The
heat source temperature is greater than heat sink temperature. Flow
of heat from the heat source 12 to heat sink 14 is accompanied by
extraction of heat and/or work 16 from the system. Conversely, flow
of heat from heat sink 14 to heat source 12 is achieved by
application of heat and/or work 16 to the system. Extraction of
heat from the heat source 12 or application of heat to heat sink 14
is achieved through a heat exchanging mechanism. Systems and
apparatus described in this disclosure are applicable to any heat
sink 14 or heat source 12 irrespective of the thermal cycle. For
descriptive purposes, a Rankine Cycle (or Organic Rankine Cycle) is
described by way of illustration, though it is understood that the
Rankine Cycle is an example thermal cycle, and this disclosure
contemplates other thermal cycles. Other thermal cycles within the
scope of this disclosure include, but are not limited to, Sterling
cycles, Brayton cycles, Kalina cycles, etc.
[0027] FIG. 1B is a schematic diagram of an example Rankine Cycle
system 100 illustrating example Rankine Cycle system components.
Elements of the Rankine Cycle 100 may be integrated into a waste
gas burner system and recover waste heat therefrom. The Rankine
Cycle 100 may be an Organic Rankine Cycle ("Rankine Cycle"), which
uses an engineered working fluid to receive waste heat from another
process, such as, for example, from the waste gas burner that the
Rankine Cycle system components are integrated into. In certain
instances, the working fluid may be a refrigerant (e.g., an HFC,
CFC, HCFC, ammonia, water, R245fa, or other refrigerant). In some
circumstances, the working fluid in cycle 100 may include a high
molecular mass organic fluid that is selected to efficiently
receive heat from relatively low temperature heat sources. As such,
the turbine generator apparatus 102 can be used to recover waste
heat and to convert the recovered waste heat into electrical
energy.
[0028] In certain instances, the turbine generator apparatus 102
includes a turbine 120 and a generator 160. The turbine generator
apparatus 102 can be used to convert heat energy from a heat source
into kinetic energy (e.g., rotation of the rotor), which is then
converted into electrical energy. The turbine 120 is configured to
receive heated and pressurized gas, which causes the turbine 120 to
rotate (and expand/cool the gas passing through the turbine 120).
Turbine 120 is coupled to a rotor of generator 160 using, for
example, a common shaft or a shaft connected by a gear box. The
rotation of the turbine 120 causes the shaft to rotate, which
in-turn, causes the rotor of generator 160 to rotate. The rotor
rotates within a stator to generate electrical power. For example,
the turbine generator apparatus 102 may output electrical power
that is configured by a power electronics package to be in form of
3-phase 60 Hz power at a voltage of about 400 VAC to about 480 VAC.
Alternative embodiments may output electrical power at different
power and/or voltages. Such electrical power can be transferred to
a power electronics system 140, other electrical driven components
within or outside the engine compressor system and, in certain
instances, to an electrical power grid system. Turbine may be an
axial, radial, screw or other type turbine. The gas outlet from the
turbine 120 may be coupled to the generator 160, which may receive
the gas from the turbine 120 to cool the generator components.
[0029] The power electronics 140 can operate in conjunction with
the generator 160 to provide power at fixed and/or variable
voltages and fixed and/or variable frequencies. Such power can be
delivered to a power conversion device configured to provide power
at fixed and/or variable voltages and/or frequencies to be used in
the system, distributed externally, or sent to a grid.
[0030] Rankine Cycle 100 may include a pump device 30 that pumps
the working fluid. The pump device 30 may be coupled to a liquid
reservoir 20 that contains the working fluid, and a pump motor 35
can be used to operate the pump. The pump device 30 may be used to
convey the working fluid to a heat exchanger 65 (the term "heat
exchanger" will be understood to mean one or both of an evaporator
or a heat exchanger). The heat exchanger 65 may receive heat from a
heat source 60, such as a waste heat source from one or more heat
sources associated with a waste gas burner. In such circumstances,
the working fluid may be directly heated or may be heated in a heat
exchanger in which the working fluid receives heat from a byproduct
fluid of the process. In certain instances, the working fluid can
cycle through the heat source 60 so that at least a substantial
portion of the fluid is converted into gaseous state. Heat source
60 may also indirectly heat the working fluid with a thermal fluid
that carries heat from the heat source 60 to the evaporator 65.
Some examples of a thermal fluid include water, steam, thermal oil,
etc.
[0031] Typically, working fluid at a low temperature and high
pressure liquid phase from the pump device 30 is circulated into
one side of the economizer 50, while working fluid that has been
expanded by a turbine upstream of a condenser is at a high
temperature and low pressure vapor phase and is circulated into
another side of the economizer 50 with the two sides being
thermally coupled to facilitate heat transfer there between.
Although illustrated as separate components, the economizer 50 (if
used) may be any type of heat exchange device, such as, for
example, a plate and frame heat exchanger, a shell and tube heat
exchanger or other device.
[0032] The evaporator/preheater heat exchanger 65 may receive the
working fluid from the economizer 50 at one side and receive a
supply of thermal fluid (that is (or is from) the heat source 60)
at another side, with the two sides of the evaporator/preheater
heat exchanger 65 being thermally coupled to facilitate heat
exchange between the thermal fluid and working fluid. For instance,
the working fluid enters the evaporator/preheater heat exchanger 65
from the economizer 50 in liquid phase and is changed to a vapor
phase by heat exchange with the thermal fluid supply. The
evaporator/preheater heat exchanger 65 may be any type of heat
exchange device, such as, for example, a plate and frame heat
exchanger, a shell and tube heat exchanger or other device.
[0033] In certain instances of the Rankine Cycle 100, the working
fluid may flow from the outlet conduit of the turbine generator
apparatus 102 to a condenser heat exchanger 85. The condenser heat
exchanger 85 is used to remove heat from the working fluid so that
all or a substantial portion of the working fluid is converted to a
liquid state. In certain instances, a forced cooling airflow or
water flow is provided over the working fluid conduit or the
condenser heat exchanger 85 to facilitate heat removal. After the
working fluid exits the condenser heat exchanger 85, the fluid may
return to the liquid reservoir 20 where it is prepared to flow
again though the Rankine Cycle 100. In certain instances, the
working fluid exits the generator 160 (or in some instances, exits
a turbine 120) and enters the economizer 50 before entering the
condenser heat exchanger 85.
[0034] Liquid separator 40 (if used) may be arranged upstream of
the turbine generator apparatus 102 so as to separate and remove a
substantial portion of any liquid state droplets or slugs of
working fluid that might otherwise pass into the turbine generator
apparatus 102. Accordingly, in certain instances of the
embodiments, the gaseous state working fluid can be passed to the
turbine generator apparatus 102, while a substantial portion of any
liquid-state droplets or slugs are removed and returned to the
liquid reservoir 20. In certain instances of the embodiments, a
liquid separator may be located between turbine stages (e.g.,
between the first turbine wheel and the second turbine wheel, for
multi-stage expanders) to remove liquid state droplets or slugs
that may form from the expansion of the working fluid from the
first turbine stage. This liquid separator may be in addition to
the liquid separator located upstream of the turbine apparatus.
[0035] Controller 180 may provide operational controls for the
various cycle components, including the heat exchangers and the
turbine generator.
[0036] FIG. 2A is a schematic illustration of an example combined
waste gas burner and thermal cycle heat exchanger 200. The combined
waste gas burner and thermal cycle heat exchanger 200 is operable
to capture the heat produced by burning waste gas 204. This heat
energy is converted into other forms of energy using the thermal
cycle. In the case of a Rankine Cycle, the heat energy is converted
into mechanical energy, which in turn can be converted to
electrical power using a generator.
[0037] Waste gas 204 is burned via the burner 202 which can be in
various configurations to suit the application. Gas combustion may
be controlled by a fan 204 that directs the air flow toward the
burner 202. In addition to providing the necessary air for
combustion, the combustor fan 206 provides a flow stream that
normally directs the flue gases to the stack or to the heat
exchanger 208. Heat exchanger 208 may be a heat exchanger for a
thermal cycle that directly heats the thermal cycle working fluid.
Heat exchanger 208 may alternatively be a heat exchanger that heats
a thermal fluid that subsequently heats the working fluid. For
example, the flow stream may assist in directing the heated gas
into a heat exchanger chamber 210 that houses the heat exchanger
208. Valves, such as valve A 212 and valve B 214 may controllably
opened and closed to control the gas flow into the heat exchanger
chamber 210. By modulating valves A and B, some or all of the hot
gas can be directed to the heat exchanger chamber 210 that houses
the heat exchanger 208. Valve A 212 proportionally controls the
flow between the flue stack 218 and heat exchanger chamber 210.
Valve B 214 controls the flow of hot gas from the heat exchanger
chamber 210 to the flue stack 218. If the thermal cycle system is
shut down, valves A 121 and B 214 can close, closing off the heat
exchanger chamber 210 to the hot gas, thereby protecting the
working fluid from high temperatures and subsequent decomposition.
The valves 212 and 214 can be operated independently or
mechanically interconnected and driven by one motor/controller. The
valves would be normally closed so that the fail safe position is
to always allow the gas to be burned and bypass the heat exchanger
208 until heat is required by the thermal cycle system. The thermal
cycle system, through its control logic, can control valves A 212
and B 214 as well as the fan to ensure maximum system operation and
generation of electric power. A portion of the electric power
produced by the thermal cycle system can be used to operate the
valves and fan shown in FIG. 2A-C and in other figures.
[0038] The combined waste gas burner and thermal cycle heat
exchanger 200 described above can include an air fan 216 that can
introduce air into the heat exchange chamber. The addition of air
allows full modulation of temperature as well as flow control
across the heat exchanger 208. Tempering air can be used to control
the heat in the heat exchanger chamber 210.
[0039] As described above, the heat exchanger 208 can be used as
either a direct evaporator for the working fluid or can indirectly
heat the working fluid: a second thermal fluid can be used to
absorb the heat energy in the heat exchanger and carry that heat
energy to a second heat exchanger located separately acting as the
evaporator in the ORC system. Indirect heating facilitates
protection of the thermal cycle system working fluid from high
temperatures. The direct heating of the working fluid is an
efficient heat transfer process that is low in cost and more
reliable due to the lower complexity.
[0040] FIG. 2B is a schematic illustration of an example combined
waste gas burner and thermal cycle heat exchanger 220. Gas
combustion is controlled by a fan as in FIG. 2A. In FIG. 2B, the
combined waste gas burner and thermal cycle heat exchanger 220
includes three butterfly valves: valve A 222, valve B 224, and
valve C 226. The valves modulate the gas flow between the flue
stack 218 and the heat exchanger chamber 210. Valve A 222 modulates
the flow of hot gases through the stack 218. Valves B 224 and C 226
control the flow of gases through the heat exchanger 208. For high
flow applications, butterfly valves provide pressure balancing.
[0041] FIG. 2C is a schematic illustration of an example combined
waste gas burner and thermal cycle heat exchanger 230. The combined
waste gas burner and thermal cycle heat exchanger 230 includes a
retractable heat exchanger 232. A bellows 234 and an expanding seal
can be used around the heat exchanger 232 to insert or detract it
from direct heat flow of the heat exchange chamber 236. By
modulating the position of the heat exchanger 232, heat transfer to
the heat exchanger 232 is controlled.
[0042] FIG. 3 is a schematic illustration of an example waste gas
burner and heat exchanger system 300. The system 300 is a bypass
scheme in which waste gas is burned in a burner 302 (e.g., a flare
or incinerator), and the hot gas is passed through a thermal cycle
system heat exchanger 320. The burner 302 includes a gas inlet 308.
Gas to be burned flows through the burner 302 through a gas riser
306 to gas discharge ports 304. A flare burner 310 may burn the
gas. The burned waste gas is directed through the flue stack 330.
By modulating valve A 326, some or all of the available hot gas can
be diverted from the flue stack 330 and into the heat exchanger
chamber 322, which houses the heat exchanger 320. Heat exchanger
320 can directly heat a thermal cycle working fluid or may heat a
thermal fluid that indirectly heats a working fluid of a thermal
cycle. A fan 324 can be used to assist the flow of gas through the
heat exchanger 320. By varying the speed of the fan 324 and/or
opening and closing valve A 326, control of heat from the burned
gas is achieved. The bypass can be mounted within the stack 330 or
at top of the stack 330. In addition to valve A, a second valve B
328 can be added so that during thermal cycle system shut down, hot
gas does not pass through the heat exchanger chamber 322. The
system 300 of FIG. 3 also includes a low pressure air riser 312, a
vaneaxial low-pressure air burner unit 314. A two-speed motor 316
is also connected to the burner 302. Air can input by an inlet bell
318.
[0043] FIG. 4 is a schematic illustration of an example waste gas
burner and heat exchanger system 400. System 400 includes a bypass
layout similar to that shown in FIG. 3, but uses natural convection
rather than a fan to assist the flow of hot gases through the heat
exchanger 408. System 400 includes a waste gas burner 404 that
burns a waste gas 406. The burned waste gas can be selectively
directed to a heat exchange chamber 410 and/or the flue vent 414 by
controlling the position of valve A 412. Bypassing in FIG. 4 is
achieved using convection created by the structure of the chamber
410 and the flue stack vent 414. A single fan and valve may be
used.
[0044] FIG. 5 is a schematic illustration of an example integrated
spiral heat exchanger 504 embedded within the structure of the flue
stack 502. Spiral heat exchanger 504 resides within a heat
exchanger chamber 505 and includes a thermal cycle fluid inlet 506
and a thermal cycle fluid outlet 508. The hot gas 510 passes
through the flue stack 502 and heats the thermal cycle working
fluid as it passes across the spiral heat exchanger 504. The gas
512 is then vented out. A fan 514 can aid in directing the fluid
across the spiral heat exchanger 504. Alternatively, the fan 515
can be located below the heat exchanger 504 to blow the burned gas
across the heat exchanger 504.
[0045] FIG. 6 is a schematic illustration of an example waste gas
burner and heat exchanger system 600. System 600 includes a flue
stack 602 housing a heat exchanger 604 within the flue stack 602
such that hot gas 606 exchanges heat with the heat exchanger 604
surface while the thermal cycle working fluid is passed within the
heat exchanger 604. The system 600 of FIG. 6 may include a flue
stack 602 that houses the heat exchanger 604 in the wall of the
flare or incinerator so that it is not directly exposed to the hot
gas 606. The coiled heat exchanger 604 can be sandwiched between an
inner and outer shell that make up the flue stack 602. A thermal
fluid or gel may be used in conjunction with this approach to
enhance the heat transfer from the hot gas 606 to the working
fluid. The system 600 may be a modular system that can connect to
existing flue stacks. To that end, it includes joints 606 and 607
to link the modular system to an existing flue stack. The embedded
heat exchanger allows for the heat exchange to take place without
impeding the flow of the burned gas 606. Heat exchanger 604 can be
of any practical design, and in some implementations, the heat
exchanger 604 may be a spiral-shaped heat exchanger.
[0046] FIG. 7 is a schematic of an example burner and thermal cycle
system 700. System 700 includes a burner 701, which may be a flare
or incinerator burner or other type of waste gas burner, and a
thermal cycle 720. System 700 uses a heated working fluid to heat
or evaporate another fluid (e.g., oil or other process liquid)
after the working fluid has been expanded by an expander 722 of the
thermal cycle. Specifically, thermal cycle expanded working fluid
may be partially or wholly cooled by another fluid, which in turn
would be heated by the expanded working fluid. The working fluid
can then be further cooled by a condenser 730.
[0047] FIG. 7 shows a burner system 701 that includes a heat
exchanger 708 housed in a heat exchanger chamber 710. Waste gas 704
is directed into a burner 702 that burns the waste gas. The burned
waste gas is directed into the flue stack 718. In some
implementations, the burned gas is directed by a combustor fan 706
can be used to direct the burned gas into the flue stack 718. The
position of valves, such as valve 712 and valve 714, can be
controlled to direct burned gas into the heat exchanger chamber
710. In the heat exchanger chamber 710, the burned gas interacts
with a heat exchanger 708, which can either directly or indirectly
heat a working fluid. The burned gas is vented out of the flue
stack 718. Another air fan 716 can be used to control the heat in
the heat exchanger chamber 710. The burner system 701 shown in FIG.
7 may include one or more alternative implementations as shown in
FIGS. 2A-C. For example, butterfly valves may be used, or a
retractable heat exchanger may be used. Similarly, one or more of
fans 706 and 716 may be optionally omitted.
[0048] The thermal cycle system 720 includes a heat exchanger 708
that directly or indirectly heats a working fluid. The heated
working fluid is directed to an expander 722. The heated working
fluid causes the expander to rotate, which rotates a rotor of the
generator 724. The rotor can be magnetically suspended to rotate
within a stator. Rotation of the rotor within the stator can
generate electric power, which is output to power electronics (PE)
726. The power can be inverted in an inverter 728. Power can be
output to a grid or consumed, either internally or externally. For
example, power from the generator may be used to power electrical
systems that are part of the thermal cycle or part of the burner
system, such as combustor fan 706 and air fan 716 and/or the
refraction mechanism shown in FIG. 2C. Similarly, the burner system
could incorporate some or all of the aspects described in
conjunction with FIGS. 2-6.
[0049] In addition, the PE can provide inverter function without
the need for a dedicated inverter unit. In certain instances, the
PE can also provide power conditioning (e.g., rectification, AC to
DC conversion, DC to AC conversion, amplification, filtering, etc.)
to power one or more electronic components of the thermal cycle
system 720 or the burner system 701.
[0050] Power electronics 726 can operate in conjunction with the
generator 724 to provide power at fixed and/or variable voltages
and fixed and/or variable frequencies. Such power can be delivered
to a power conversion device configured to provide power at fixed
and/or variable voltages and/or frequencies to be used in the
system, external, or to the grid. The output of the electric power
system provides power at a variable voltage or frequency to drive
with adjustable speed a fan motor on the burner 701 or to an
electric motor or to another electric device driven by a variable
speed drive. The output of the electric power system can provide
fixed voltage and frequency for ancillary equipment such as a fan
motor, an oil pump, an electrically driven compressor, or other
electric device driven by a fixed voltage and/or frequency.
[0051] As mentioned above, the working fluid is expanded by
expander 722 and directed to fluid heater 736 prior to being
directed to a condenser 730. The fluid heater 736 can use residual
heat from the working fluid after expansion to heat another fluid
738 and to cool the working fluid. An example fluid is crude oil.
As crude oil emerges from the well or other process, it can be
heated from 60-70 degrees F. to 100-120 degrees F. for processing
or final dispatch using the expanded working fluid. The heated
fluid can be stored in a tank 740.
[0052] Thermal cycle systems may use a condenser to cool the
working fluid from a gaseous to liquid state. Condenser heat
rejection is a major component of parasitic loads associated with
an thermal cycle system. In plants where a stream of cold fluid
requires heating, the thermal cycle condenser can be partially or
wholly replaced by allowing the thermal cycle working fluid to
exchange heat with the cold fluid stream. Specifically, flare gas
applications are generally part of crude oil production. Often the
oil emerging from the well at 60-70 F needs to be heated to 100-120
F for further processing or transport. Using the thermal cycle
system to recover the waste heat from flare and heating the
produced oil, using expanded thermal cycle working fluid, adds two
distinct and simultaneous benefits to overall production whilst
reducing the parasitic load on the thermal cycle system.
[0053] The working fluid can be directed from the fluid heater 736
to a condenser 730 where it is cooled. It can then be stored in a
receiver tank 732. Pump 734 can pump the cooled working fluid from
the receiver tank 732 into the heat exchanger 708.
[0054] FIG. 8A is a schematic illustration of an example heat
transfer system 800. In system 800, the heat transfer takes place
in one common chamber 802 with a fire tube-type burner 806, heat
exchanger 808, and other process liquid heat exchanger 814. In
system 800, heat from burned gas is directed through a fire tube
810 and out of a flue stack 812. The fire tube 810 resides within a
thermal bath 802 that is filled with a thermal fluid 804. The
thermal fluid (e.g., glycol) can transfer heat from the fire tube
810 to thermal cycle heat exchanger 808 and process heat exchanger
814. The heated thermal cycle working fluid can be used to produce
electric power. The thermal cycle heat exchanger 808 can heat the
working fluid directly or indirectly via another fluid transferring
the heat to another external heat exchanger (not shown). The
thermal bath may be an oil/gas/water separator tank.
[0055] FIG. 8B is a schematic illustration of an example heat
transfer system 820. System 820 is similar to that shown in FIG.
8A, except that in system 820, the second process fluid 822 to be
heated acts as the thermal transfer fluid between the fire tube 810
and the thermal cycle heat exchanger 808. The process fluid 822
enters the thermal bath 821 through a process fluid inlet 824. It
fills the thermal bath 821 to the extent that it can transfer heat
between the fire tube 810 and the thermal cycle heat exchanger 808.
It can then be directed out of the thermal bath 821 by a process
fluid outlet 826.
[0056] FIG. 9A is a schematic illustration of an example of dual
waste gas burner and heat exchanger system 900. The system 900
includes two portions: a first portion 901a and a second portion
901b, each portion separated by a thermal barrier 903. In the
example shown in FIG. 9A, the first portion 901a is a first chamber
and the second portion 901b is a second chamber. The system 900
includes two burners: burner A 902 and burner B 904. Waste gas 906
enters the burners 902 and/or 904 via a modulating valve 908 where
the proportion of gas to each burner can be controlled. Burner A
902 facilitates combustion of waste gas 906 with or without the aid
of combustor fan A 910. Hot gases may then be exhausted through the
flue stack 912. In the case of incinerator applications, the hot
gases may be directed elsewhere, such as to another process.
Similarly burner B 904 facilitates combustion of waste gas 906. Hot
gases are passed through a heat exchanger 914 housed in the second
chamber, which is referred to here as a heat exchanger chamber 916,
and are then admitted to the flue stack 912 from the heat exchanger
chamber 916 via an aperture, referred to here as a heat exchanger
chamber outlet 918. Burner B 904 facilitates combustion of waste
gas 906 with or without the aid of combustor fan B 920. The heat
exchanger chamber outlet 918 can be structured or configured to
restrict the flow of burned waste gas from the first portion 901a
into the second portion 901b, the result being that the temperature
of the second portion 901b is not affected when the burner 904 is
not burning waste gas. In some implementations, the thermal barrier
903 is an insulated wall, which also aids in controlling the
temperature in each chamber.
[0057] Heat exchanger 914 resides outside of the first portion 901a
of system 900. Heat exchanger 914 is out (substantially or
entirely) of the convective heat flow from burner A 902. In other
words, heat exchanger 914 receives heat from burned gas from burner
B 904 in the second portion 901b. Heat exchanger 914 can directly
heat a thermal cycle working fluid or may indirectly heat a thermal
cycle working fluid by heating a thermal fluid that heats the
working fluid of a thermal cycle. The heat exchanger chamber outlet
918 allows hot gases from burner A 902 to aid the flow of gases
from burner B 904 through the flue stack 912, thereby eliminating a
need for an exhaust fan. Furthermore design of the heat exchanger
chamber outlet 918 can be elected so that hot gases from burner A
902 cannot enter the heat exchanger chamber 916.
[0058] Fans 910 and 920 can aid in controlling the temperature
within each respective chamber. Additionally, the fans 910 and 920
can be controlled by the thermal cycle system to control the
heating of the working fluid. For example, the thermal cycle system
controller 180 can send control signals to fans 910 and/or 920.
Valve 908 can likewise be controlled by the thermal cycle system to
control the heating of the working fluid. That is, the thermal
cycle system can control valve 908 to adjust the amount of waste
gas burned in each chamber, thereby controlling the heat applied to
the heat exchanger 914 in chamber 901b.
[0059] FIG. 9B is a schematic illustration of another example dual
waste gas burner and heat exchanger system 930. System 930 includes
a first portion 931a residing above a second portion 931b. In the
implementation shown in FIG. 9B, the first portion 931a is
separated from the second portion 931b by a thermal barrier 933.
The system 930 includes two burners: burner A 932 and burner B 936.
Waste gas 948 enters chambers in which burners 932 and/or 936
reside via a modulating valve 946. Modulating valve 946 controls
the proportion of gas to each burner. Valve 946 may be controlled
by the thermal cycle system to control the amount of heating of the
working fluid. Burner A 932 facilitates combustion of waste gas 948
with or without the aid of a fan 944. Hot gases are then exhausted
through the flue stack 942. Similarly burner B 936 facilitates
combustion of waste gas 948. Burned gas is passed from the burner B
936 to a heat exchanger 938 housed in a heat exchanger chamber 940
(in this case, heat exchanger chamber 940 is the second portion
931b). The burned gas is then passed to the burner A chamber 934
housing burner A 932 via an aperture, heat exchanger chamber outlet
950, and out through the flue stack 942. Burner B 936 facilitates
combustion of waste gas 948 with or without the aid of the fan 944.
Heat exchanger 938 can directly heat a thermal cycle working fluid
or may indirectly heat a thermal cycle working fluid by heating a
thermal fluid that indirectly heats the working fluid of a thermal
cycle. The aperture heat exchanger chamber outlet 950 allows hot
gases from burner A 932 to aid the flow of gases from burner B 936
through the flue stack 942 through the Venturi effect. Furthermore,
design of the heat exchanger chamber outlet 918 can be elected so
that hot gases from burner A 932 cannot enter the heat exchanger
chamber 938. Accordingly, heat exchanger 938 receives heat from
burned gas in the second portion 931b from burner B 936.
[0060] One or both of fan 944 or valve 946 can be controlled by the
thermal cycle system (e.g., through thermal cycle system controller
180). For example, the thermal cycle system can send control
signals to the fan 944 so that the fan 944 can aid in adjusting the
temperature in the heat exchanger chamber 940. By controlling the
fan, the amount of heat transferred to the thermal cycle working
fluid through the heat exchanger 938 can be adjusted. Likewise, the
temperature in the heat exchanger chamber 940 can be controlled by
operating the valve 946 to change the amount of waste gas
burned.
[0061] FIG. 10 is a schematic illustration of an example combined
waste gas burner and thermal cycle heat exchanger system 1000. The
combined waste gas burner and thermal cycle heat exchanger system
1000 is operable to capture the heat produced by burning waste gas.
This heat energy is converted into other forms of energy using the
thermal cycle (e.g., thermal cycle generator system 100). In the
case of a Rankine cycle, the waste gas burner and thermal cycle
heat exchanger system 1000 is used as or with the Rankine cycle's
evaporator and heat source (e.g., evaporator 65 and heat source 60
of FIG. 1B).
[0062] The waste gas burner and thermal cycle heat exchanger system
1000 can include a housing 1002 that defines a flue 1004. In
certain instances, the housing 1002 can be that of an incinerator,
a furnace, a burner, a flare, a thermal oxidizer, and/or another
system for burning or destroying waste gas. To this end, waste gas
is introduced into and burned with a burner 206 within the housing
1002, which can be in various configurations to suit the
application. In certain instances, the burner 1006 is a burner
configured to output its heat substantially as radiant heat, for
example, outputting more radiant heat than convective heat. In one
example, the burner 1006 is an infrared burner having a high
radiance emitter heated by the burning waste gas, such as metal
alloy foam emitter, a ceramic emitter and/or another configuration
of emitter. The burner 1006 can have heat shields or be otherwise
configured to direct and focus the radiant heat in a primary
heating direction. The burner 1006 can be more than one burner.
[0063] In certain instances, the burner 206 can include multiple
types of burners. For example, the burner 1006 shown in FIG. 10 is
a burner configuration having a burner 1006a configured primarily
for efficient destruction of the waste gas, regardless of the type
of heat output by the burner, and a burner 1006b configured to
output its heat substantially as radiant heat. In other instances,
the burners 1006a can be of the same configuration.
[0064] A heat exchanger 1008 is positioned in the housing 1002
adjacent to and out (substantially or entirely) of the upward
convective heat flow from the burner 1006. The burner's primary
heating direction is oriented toward the heat exchanger 1008 (i.e.,
down) and the heat exchanger 1008 is in line of sight of the burner
1006. Thus, the combustion byproducts and burnt impurities flow
upward and exit through the flue 1004, as does a substantial amount
of the convective heat, and the radiant heat is directed downward
toward the heat exchanger 208. The heat exchanger 1008 may be
associated with a thermal cycle in that it directly heats the
thermal cycle working fluid and/or heats a heat exchange fluid that
subsequently heats the working fluid, for example, via another heat
exchanger outside of the housing 1002. The burner 1006 thus can be
the heat source to the thermal cycle (e.g., heat source 60 of FIG.
1B) and the heat exchanger 1008 can be the evaporator to the
thermal cycle (e.g., evaporator 65) or used in heating the
evaporator to the thermal cycle. With the heat exchanger out
(substantially or entirely) of the upward convective heat flow from
the burner 1006, the combustion byproducts and impurities in the
waste gas are carried up the flue 1004 and away from the heat
exchanger 1008. Therefore, this reduces deposition of these
combustion byproducts and impurities on the heat exchanger 1008,
and enables the system 1000 to burn high impurity waste gas. In
FIG. 10, the heat exchanger 1008 is shown below the burner 1006. In
other instances, the heat exchanger 1008 can be positioned
differently relative to the burner 1006. For example, the heat
exchanger 1008 can be positioned to a side of the burner 1006 and
the burner's primary heating direction oriented to the side. Still
other configurations exist.
[0065] In certain instances, the heat exchanger 1008 can include a
radiant heat collector 1014 thermally coupled to coils 1016. The
coils 1016 contain the thermal cycle working fluid or the heat
transfer fluid that is used in transferring heat to the thermal
cycle working fluid. The coils 1016 can be coils of a tube type
heat exchanger and/or another configuration. In certain instances,
the coils 1016 can be thermally bonded to the radiant heat
collector 1014 to achieve conductive heat transfer and/or can be
thermally coupled in another manner.
[0066] In certain instances, the radiant heat collector 1014 is
conical to correspond with a cylindrical burner 1006 and/or housing
1002 or a triangular cross-section trough to correspond with a
rectangular burner 1006 and/or housing 1002. Other shapes of
collector 1014, burner 1006 and housing 1002 exist and the shape of
the collector 1014 need not correspond with the shape of the
housing 1002. In a conical or trough style heat collector 1014, the
angle of the radiant heat collector 1014 surfaces to the burner
1006 can be selected in connection with the surface area and
emissivity based on the desired of heat transfer. One or more
surfaces of the heat collector 1014 and/or coils 1016 can have a
specified emissivity selected based on the desired heat transfer.
Further, the coils 1016 can be sized in connection with the radiant
heat collector 1014. For example, in certain instances, the waste
gas may burn at a temperature of five to ten times the operating
temperature of the working fluid, and the burner 1006, heat
collector 1014 and coils 1016 can be sized or configured to
maintain that ratio without overheating the working fluid.
[0067] A number of embodiments have been described. Nevertheless,
it will be understood that various modifications may be made.
Accordingly, other embodiments are within the scope of the
following claims:
* * * * *