U.S. patent application number 13/703167 was filed with the patent office on 2013-04-18 for flue having an adjustable flue gas flow unit.
The applicant listed for this patent is Klaus Schmitt. Invention is credited to Klaus Schmitt.
Application Number | 20130092105 13/703167 |
Document ID | / |
Family ID | 45111268 |
Filed Date | 2013-04-18 |
United States Patent
Application |
20130092105 |
Kind Code |
A1 |
Schmitt; Klaus |
April 18, 2013 |
FLUE HAVING AN ADJUSTABLE FLUE GAS FLOW UNIT
Abstract
Known chimneys or chimney furnaces use flue gas flow units for
heating buildings, said devices having displaceable or fixed
obstacles for deflecting flue gas for generating flue gas
turbulence. The invention relates to a device and method for
transferring heat through a flue gas discharge pipe (28) in which
(44, 45) pivotal guide plates (37) are inserted in the longitudinal
direction of the pipe run, at which the flue gas flow (22) is more
or less deflected in a sinuous line as function of the pivot angle
(24) of the guide plates (37) that can be adjusted during furnace
operation. A fan (19) can increase the flue gas flow (22). An
optional furnace heat exchanger (29) generates additional hot water
as needed. The controller (5) activates the actuators for the fan
(19), guide plate pivot angle setting (24), and at least one
circulating pump (10 or 11) as a function of the prescribed
controlled variables such as flue gas temperature, reservoir
temperature, heat exchanger performance, or flue gas flow.
Inventors: |
Schmitt; Klaus; (Dortmund,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Schmitt; Klaus |
Dortmund |
|
DE |
|
|
Family ID: |
45111268 |
Appl. No.: |
13/703167 |
Filed: |
May 31, 2011 |
PCT Filed: |
May 31, 2011 |
PCT NO: |
PCT/DE2011/001141 |
371 Date: |
December 26, 2012 |
Current U.S.
Class: |
122/18.4 ;
431/20 |
Current CPC
Class: |
F23J 15/06 20130101;
F24D 12/02 20130101; Y02B 10/20 20130101; F23M 9/003 20130101; F24H
1/165 20130101; F23N 2235/08 20200101; Y02E 20/30 20130101; F23N
2233/10 20200101; Y02B 10/70 20130101; Y02B 30/14 20130101; F24D
17/0068 20130101; F23N 2233/04 20200101; Y02E 20/363 20130101; Y02A
30/62 20180101; Y02A 30/60 20180101; F23L 11/00 20130101; F24D
11/004 20130101; F24H 9/0031 20130101; Y02B 30/00 20130101; F24B
9/04 20130101; F24D 11/003 20130101 |
Class at
Publication: |
122/18.4 ;
431/20 |
International
Class: |
F24H 1/16 20060101
F24H001/16; F23L 11/00 20060101 F23L011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 10, 2010 |
DE |
10 2010 023 381.1 |
Claims
1-14. (canceled)
15. A flue heat transfer system for transferring heat from a
furnace heat source in a flue gas pipe, said flue heat transfer
system comprising: a heat exchanger integrated in a flue gas pipe
and possessing a liquid media chamber, impinged by an
all-enveloping flue gas flow, said heat exchanger comprising an
inner and outer heat exchanger regions, and pivotal guide plates,
said inner and outer heat exchanger regions being configured to be
impinged by said flue gas flow, said pivotal guide plates are
arranged spatially one behind the other in a longitudinal direction
in said inner heat exchanger region; wherein said guide plates are
configured to deflect said flue gas flow from said inner heat
exchanger region into said outer heat exchanger region up to an
exterior wall of said flue gas pipe, such that, at low flue gas
temperatures, said guide plates do not cause any deflections of
said flue gas flow through said heat exchanger regions and that,
with increasing flue gas temperatures, deflections of said flue gas
flow as well as a resulting flue gas flow turbulences increase with
decreasing angles of said guide plates.
16. The flue heat transfer system according to claim 15, wherein
each of said guide plates are pivotable so as to adjust an angle of
each of said guide plates to said flue gas flow about a pivoting
axis of said guide plates.
17. The flue heat transfer system according to claim 16, wherein
said angle of each of said guide plates are adjusted jointly by
mechanically-coupled connecting elements comprising a first rotary
lever mechanically connect to a first lever rod, said first lever
rod is mechanically connected to at least a first of said guide
plates and is configured to pivot said first of said guide plates,
a second rotary lever mechanically connect to a second lever rod,
said second lever rod is mechanically connected to at least a
second of said guide plates successive to said first of said guide
plates and is configured to pivot said second of said guide plates,
and a connect rode mechanically connected to said first and second
lever rods, said mechanically-coupled connecting elements being
configured to allow a synchronous angle setting of said guide
plates with a reversed angular orientation from one of said guide
plate to another of said guide plates.
18. The flue heat transfer system according to claim 17, wherein
one of said first and second rotary levers is fitted with at least
one drive means selected from the group consisting of a servo drive
means, an electrically-driven servo drive means, and a rotary drive
means, said drive means is configured for adjusting angular
positions of said guide plates.
19. The flue heat transfer system according to claim 16 further
comprising a part-turn valve actuator means configured for
adjusting said angle of said guide plates, wherein said part-turn
valve actuator means is one of being fitted to each of said guide
plates, and fitted to a group of said guide plates which are
mechanically-coupled to each other.
20. The flue heat transfer system according to claim 17, wherein
said heat exchanger is configured for transferring a liquid heat
carrier medium, said heat exchanger comprising at least one conduit
configured to form a hollow body with said inner heat exchanger
region configured to receive said guide plates and said
mechanically-coupled connecting elements.
21. The flue heat transfer system according to claim 20, wherein
said conduit is a plurality of tubular rods, which together, by
using a plurality of 180.degree. pipe bends, form a plurality of
pipe loops that are interconnected in series to form said hollow
body of circular shape, said pipe loops are configured to be
impinged by said enveloping flue gas flow, and wherein said heat
exchanger is provided with a connecting sleeve for a return flow at
a starting point and a connecting sleeve for a feed flow at an end
point.
22. The flue heat transfer system according to claim 20, wherein
said conduit is a plurality of tubular rods, which, by means of two
hollow rings, respectively provided at a beginning point and an end
point of said tubular rods, are interconnected by welding, such
that said hollow body of circular shape is obtained, a first of
said hollow ring being provided with a connecting sleeve for a
return flow and a second of said hollow rings being provided with a
connecting sleeve for a feed flow, said hollow rings are configured
to be impinged by said enveloping flue gas flow.
23. The flue heat transfer system according to claim 20, wherein
said conduit is a coiled pipe, which consists of a circularly
curved pipe and each individual loop of which includes an air gap
for impinging said heat carrier medium by an all-enveloping said
flue gas flow.
24. The flue heat transfer system according to claim 20, wherein
said conduit is a liquid jacket, arranged between two jacketing
pipes associated with said flue gas pipe, said heat carrier medium
flows through said jacketing pipes, and wherein an air gap is
defined between an outer jacketing pipe surface and an inner
surface of said flue gas pipe for a portion of said flue gas flow
to flow through.
25. The flue heat transfer system according to claim 15 further
comprising an electrically-driven fan installed and configured for
regulating said flue gas flow in one of said flue gas discharge
pipe, in a fireplace, in a chimney, at an end of a chimney,
adjacent to said flue gas discharge pipe, and in a region of a
fresh air supply of a furnace.
26. The flue heat transfer system according to claim 15 further
comprising a buffer storage device configured to transfer and store
heat.
27. The flue heat transfer system according to claim 17, wherein
each of said guide plates further comprises a hinge mechanically
connected to said first and second lever rods respectively.
28. The flue heat transfer system according to claim 17, wherein
said connecting rod mechanically interconnects said first and
second rotary levers in diagonally rotatable fashion, said
connecting rod being configured to produce an opposite, but
synchronous direction of motion of said first and second lever
rods.
29. The flue heat transfer system according to claim 15, wherein
said guide plates each featuring textured surfaces configured to
increase friction of said flue gas flow.
30. A method of using a heat transfer system for transferring heat
from a furnace heat source, said method comprising the steps of: a)
setting a flue gas flow while a furnace is heating up by one of
manual operation, and automatic control operation; and b) setting a
rotational speed of ventilation and an angular position of guide
plates in a heat exchanger integrated in a flue gas pipe of said
furnace by one of stepwise, and continuously; wherein said guide
plates are configured to deflect said flue gas flow from an inner
heat exchanger region into an outer heat exchanger region up to an
exterior wall of said flue gas pipe, such that, at low flue gas
temperatures, said guide plates do not cause any deflections of
said flue gas flow through said heat exchanger regions and that,
with increasing flue gas temperatures, deflections of said flue gas
flow as well as a resulting flue gas flow turbulences increase with
decreasing angles of said guide plates.
31. The method according to claim 30, wherein step b) is performed
on at least one basis selected from the group consisting of current
actual values of flue gas temperatures, temperatures of said flue
gas pipe, temperatures of said flue gas flow, said heat exchanger
output by means of manual adjustment, and said heat exchanger
output by means of automatic adjustment by way of a control
system.
32. The method according to claim 30, wherein said method is used
for a purpose of producing hot water by said flue heat exchanger,
and wherein said method further comprising the steps of: c)
coupling a heat generator and said flue gas pipe in parallel to
produce parallel heating circuits, such that said heat generator
and said flue gas pipe supply thermal energy by using a heat
exchanger in a heat accumulator via a joint heating circuit by
means of a liquid heat carrier media, such that a control system
activates actuators via control signals and that in a case of said
actuators or in a case of one of said actuators is inactive a
simultaneous media flow between said parallel heating circuits is
prevented by check valves.
33. The method according to claim 32, wherein said parallel heating
circuits are used, which have, in particular, a higher media
temperature when compared to a media temperature in a heat
accumulator, or a current energy content of which prevails, and
that, in this context, at least one of said parallel heating
circuits are activated simultaneously.
Description
TECHNICAL FIELD
[0001] The invention relates to an apparatus and a method for
supplying heat by means of a furnace heat source, which deflects
the flue gases in an alternating manner via a guide plate system
arranged in the flue and adjustable during operation, and which
utilises the thermal energy in a more efficient manner.
[0002] The heat exchanger, optionally preferably mounted in the
interior of a flue gas discharge pipe, operates in conjunction with
the guide plate system and feeds the thermal energy to a hot water
system.
[0003] Thermal energy storage of the parallel heat generators is
performed by using a heat accumulator, for example for heating
buildings and/or for producing hot water from drinking water.
STATE OF THE ART
[0004] Known chimneys or chimney furnaces use flue gas flow devices
for heating buildings, said devices having displaceable or fixed
obstacles for deflecting flue gas for generating flue gas
turbulences.
[0005] Pivotable insert elements for hot gas flues are known which,
for reasons of easy cleaning, are designed to be loose and
removable in order to reduce the cross-section (see DE 189989U:
Page 1, paragraph 1; page 2, paragraphs 3 and 4 as well as angular
positions of FIGS. 1 and 2).
[0006] Furthermore, flue gas guide inserts are known, which are
movably-adjusted once with a tool during start-up by a specialist
technician at a determined, fixed position in accordance with the
respectively desired operating conditions based on practical tests
on site (see DE 9216274U1 page 4, paragraph 1 as well as FIG. 2 by
means of nut 12). The rectangular guide plate sections are tightly
screwed or welded to one another and rest on one side against the
flue gas pipe wall (page 6, paragraph 2) or consist of a metal
strip (page 10, paragraph 3).
Presentation of the Technical Problem and Means for the Technical
Solution thereof
[0007] The known immovable or movable flue gas flow devices are not
variably adjustable while the furnace heats up or in the course of
the ongoing combustion process.
[0008] The flue gas flow devices are either suspended
connectionless in the flue gas pipe, without any adjusting device
being accessible from outside, or are to be adjusted by technical
specialists by means of internal screw connections for an
application during start-up in order to take into account the
desired operating conditions.
[0009] Manual setting by the operator or automatic setting via a
control system is not provided.
[0010] The known movable flue gas flow devices do not use a flue
gas pipe heat exchanger and are thus not in a position to withdraw
additional thermal energy from the flue gas pipe and to feed it to
another parallel heat circuit.
[0011] The apparatus according to the invention and the method
associated therewith allow a variable setting of the flue gas flow
during furnace operation or while the furnace is heating up.
[0012] The flue gas flow (22) is set by a plurality of guide plates
(37), pivotal about their own central axes, which guide plates are
arranged spatially one behind the other in the flue gas pipe (28)
in the longitudinal direction and which are deflected from guide
plate to guide plate as a function of the alternating pivot angles
(24). The deflection occurs to a greater or lesser extent in a
pronounced meandering pattern (FIG. 5), depending on the setting of
the angular position of the guide plates. The maximum deflection
occurs over the entire flue gas cross-section.
[0013] The generation of the meandering deflection of the flue
gases by the required alternating pivotal guide plates is
preferably brought about in that, for a mechanical connection of
the rotary levers (35 and 36), a connecting rod (43) is provided at
the respectively opposite pivot points of the rotary levers (35 and
36), which, interconnected in this way, allows a synchronous guide
plate adjustment, but in an opposite angle sense (24) from one
guide plate (37) to the next (FIG. 2).
[0014] A heat exchanger (29), impinged by an all-enveloping flow of
flue gas, which is likewise arranged in the longitudinal direction
of the flue gas pipe between the pivotal guide plates (37) and the
inner pipe wall of the flue gas discharge pipe (28), transmits the
thermal energy to a hot water system, increases the turbulent flow
and, due to the integration within the flue gas discharge pipe, has
a large heat exchanger surface.
[0015] For accommodating the pivotal guide plates, the pipe heat
exchanger includes a spatially free, gaseous flow chamber, inside
which the guide plates, arranged in succession, can be pivoted.
[0016] An electrically-driven fan is used for increasing the flue
gas flow or for regulating the oxygen supply, preferably in the
fresh air region, in conjunction with the pivotal guide plates and
their flow-inhibiting action.
[0017] The activation of the fan takes place as a function of the
desired heat output of the flue heat exchanger and/or the desired
flow velocity in the flue gas pipe and/or the temperature in or on
the flue gas pipe by way of the control system or by way of manual
operation.
[0018] The inventive benefit allows a variable adjustability of
combustion as a function of the respectively prevailing operating
conditions. As a result thereof, the oxygen supply by ventilation,
on the one hand, is utilised as a control variable and the flue gas
flow, on the other hand, becomes to a greater or lesser extent
turbulent or is inhibited, so that higher temperatures occur in the
combustion chamber as a result of the longer residence time of the
flue gases.
[0019] In the liquid flow chamber serving to transfer heat to the
heat accumulator, each parallel heating circuit (1, 2) disposes of
its own actuator which can be activated and adjusted independently
of the control system and which consists preferably of a
circulation pump.
[0020] By means of the flow rate limiter (20, 21) associated with
each heating circuit, the media circuit resistances and/or the
media flow rates can be adjusted separately for each heating
circuit, either manually or automatically.
[0021] The use of heat carrier liquids, water or solar liquid, is
provided for the liquid media region in the flue heat exchanger
(29) and the other parallel heating circuits (1).
DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1: Integrated flue heat exchanger with adjustable flue
gas flow device serving as heat generator coupled in parallel
[0023] FIG. 2: Pivotal guide plates, including the mechanical
connecting elements for synchronous angle setting of the guide
plates
[0024] FIG. 3: Sectional drawings through the flue gas discharge
pipe at 0.degree. and 90.degree. angle settings of the guide
plates
[0025] FIG. 4: Flue heat exchanger, designed with an
internally-inserted coiled pipe
[0026] FIG. 5: Representation by way of example of the effect on
the flue gas flow caused by the guide plates
[0027] FIG. 6: Flue heat exchanger, designed with
internally-inserted water jacket heat exchanger
[0028] FIG. 7: Tubular rod heat exchanger with feed flow and return
flow hollow ring
[0029] FIG. 8: Tubular rod heat exchanger with 180.degree.
loop-shaped pipe bends
[0030] FIG. 9: Output comparison pipe jacket heat exchanger
with/without flue gas deflection and ventilation
[0031] FIG. 10: Output control with control variable `fan`
Embodiment Example, Types of Embodiments with Indication Of
Numerals
(sic) Types of Heating Circuits
[0032] A thermal solar installation, supplemented by a chimney
furnace installation coupled in parallel, serves as an example of
an embodiment for heat transfer for the purpose of heating and hot
water generation. It concerns the use of two
discontinuously-operating heat sources. Neither the solar plant
(1), nor the chimney furnace installation (2) is energetically
permanently available or operating continuously. Only with
sufficient availability are they used additionally as a supplement
to a continuously-operating heat source, the basic system. In
contrast thereto, the basic system, also referred to as primary
system, is permanently available, operates completely autonomously,
such that the parallel heating circuits reduce the energy
requirement of the basic system in the embodiment.
[0033] Embodiment types are possible which use the chimney furnace
installation (2) as the basic system.
[0034] In the embodiment exemplified, the solar installation serves
as the heat source for the parallel heating circuit 1 (1) while the
chimney furnace installation serves as the furnace heat source for
the parallel heating circuit 2 (2). The heating circuits, coupled
in parallel, supply a heat exchanger (4), which supplies the hot
water storage means or the heat accumulator (3) with thermal
energy. The heat accumulator (3) is used both for hot water
generation as well as for supporting the heating system. FIG. 1
shows the overall arrangement of the heating circuits (1, 2),
coupled in parallel, including the components and functions
relevant to the invention. The representation of the components of
the real plant, serving for plant safety and operational
maintenance, was dispensed with. Both for the solar plant as well
as for the expansion of the chimney furnace installation, the
following components were used additionally, but are not shown:
[0035] 2 mechanical temperature display devices
[0036] Mechanical pressure gauge for pressure display
[0037] Hand-operated shut-off valves
[0038] Overflow valve with blow-off system in the event of
excessive pressure
[0039] Connection for an excess pressure storage means
[0040] Excess pressure storage means
[0041] Filling pump
The vent valve (30) is mounted at the highest point of the heating
circuit (2), either in the inner or the outer region of the flue
heat exchanger (29). The required values of the hystereses for safe
switching on and off of the respective actuators are not mentioned
in the description of the embodiment and in the patent claims, but
form part of the practical execution of real-world
applications.
[0042] Function principle: Integrated flue heat exchanger with
pivotal guide plates
[0043] in the embodiment exemplified, the heat transfer from the
chimney furnace installation is performed via a flue heat exchanger
(29), which exploits the flue gases (22) of the furnace heat source
(2) due to its hollow body design and the integrated installation
in the flue gas discharge pipe (28) both in the interior gaseous
media chamber (44) as well as in the exterior gaseous media chamber
(45) of the flue heat exchanger (29). In the inner hollow body
section (44), preferably 6 pivotal guide plates (37) are arranged
spatially one behind the other in the longitudinal direction of the
flue gas pipe (28) in such a manner that the flue gases (22)
flowing therethrough are forcibly guided and deflected. Depending
on the pivot angle setting (24) of the guide plates (37), a
deflection of the flue gas flow (22) takes place to a greater or
lesser extent. The angle setting (24) of the pivotal guide plates
(37) is performed by actuating an associated rotary lever (35 or
36) about the shaft axis of the guide plates (37) in an effective
angular range from 0.degree. to 90.degree., so that the effective
area cross-section increases with ascending degrees of the angle
(24) for an unimpeded flue gas flow (22). The radial pivoting
process of the guide plates (37), with increasing pivot angles (24)
from position 0.degree. towards 90.degree., results in an
increasing cross-sectional area for the effective flue gas flow in
the inner gaseous flow chamber (44). In the reverse direction,
decreasing pivot angles (24) bring about smaller cross-section
areas, which forcibly deflect and inhibit the flue gas flow (22),
so that with decreasing pivot angles (24) of the guide plates a
stronger, turbulent flow within the entire gaseous media chamber
(44 and 45) occurs as shown schematically in FIG. 5. The turbulent
flue gas flow creates higher friction in the entire gaseous flue
heat exchanger region (44, 45), clearly improving the efficiency of
heat transfer.
[0044] The guide plates (37) used in the embodiment exemplified
according to FIG. 2 are mechanically interconnected for specific
and mutual adjustability.
[0045] A first mechanical connection is brought about by a pivoting
lever rod 1 (41), as shown in FIG. 2, which interconnects three
pivotal guide plates (37) in such a manner that by actuating the
rotary lever 1 (35) identical pivot angles (24) come about as a
result of the synchronous motion sequence of these
mechanically-interconnected guide plates (37). For this purpose,
each second guide plate (37) to be connected, starting with the
1.sup.st guide plate, followed by the 3.sup.rd guide plate and
ending with the 5.sup.th guide plate in the longitudinal direction
of the flue gas discharge pipe (28), requires, in each case, one
mechanical hinge with a pivot point (38) per guide plate (37), the
said hinge being mechanically connected to the pivoting lever rod 1
(41).
[0046] A second mechanical connection is brought about by a further
pivoting lever rod 2 (42), as shown in FIG. 2, which interconnects
three pivotal guide plates (37) in such a manner that by actuating
the rotary lever 2 (36) identical pivot angles (24) come about as a
result of the synchronous motion sequence of these
mechanically-interconnected guide plates (37). For this purpose,
each second guide plate (37) to be connected, starting with the
2.sup.nd guide plate, followed by the 4.sup.th guide plate and
ending with the 6.sup.th guide plate in the longitudinal direction
of the flue gas discharge pipe (28), requires, in each case, one
mechanical hinge with a pivot point (38) per guide plate (37), the
said hinge being mechanically connected to the pivoting lever rod 2
(42).
[0047] The two pivoting lever rods (41, 42) are arranged spatially
opposite one another on the right side and the left side in the
outer region of the guide plates (37) in relation to their axis of
rotation, as shown in FIG. 2. The corresponding representation in
FIG. 3 shows in section A, at the angular position 0.degree. of the
guide plates, the hinges (38) of two guide plates (37) mounted on
the right and the left side with a connection, preferably brought
about mechanically, of the pivoting lever rod 1 (41) and the
pivoting lever rod 2 (42) to the hinges (38). The angle setting of
0.degree. (39) of the guide plates shows a virtually completely
open flue gas pipe cross-section. Section A at an angle setting of
90.degree. (40) of the guide plates, according to FIG. 3, on the
other hand, shows a virtually completely closed flue gas pipe
cross-section.
[0048] By means of a connecting rod (43), mechanically
interconnecting the two rotary levers (35 and 36) in diagonally
rotatable fashion, an opposite, but synchronous direction of motion
of the two pivoting lever rods 1 and 2 (41, 42) is attained. This
results in identical pivot angle (24) values with a reversed
angular orientation from one guide plate (37) to the next. The
synchronous pivot angle setting of the guide plates (37) results in
a virtually identical flow distribution in the direction of the
media flow, even for varying pivot angles (24), when viewed in the
longitudinal direction of the flue gas flow (22). The mechanical
coupling by mechanical connecting elements (41, 42 and 43) results
in a maximum pivot angle range (24) of the guide plates of
approximately -90.degree. to +90.degree..
[0049] Since the angle setting of the guide plates of -90.degree.
or 90.degree., as shown in FIG. 3 by FIG. 40), represents the
greatest possible area cross-section in relation to the flue gas
flow, this angle setting (24) is particularly suited for cleaning
the flue heat exchanger elements and is furthermore a favourable
angle setting for the heating-up process of the furnace system
(47).
[0050] Embodiment types are conceivable, wherein fewer or more than
6 guide plates are used. It is furthermore also possible to
dispense with mechanical coupling for a synchronous angle setting
entirely or in part.
Embodiment Types of the Flue Heat Exchangers
[0051] The flue heat exchanger (29) used in the embodiment
exemplified, consists of a plurality of tubular steel rods, which
are interconnected by using a plurality of 180.degree. pipe bends,
as shown in FIG. 8. The arrangement is impinged by the enveloping
flow of the gaseous heat carrier medium, similarly to what is shown
in FIG. 5. The spatial arrangement of the tubular rods as well as
the pipe bends associated therewith is done in a loop pattern so
that a hollow body of round shape is obtained inside the flue gas
pipe (28). The hollow body offers the space required for
accommodating the pivotal guide plates (37) and is provided with
the return flow connecting sleeve (27) at the beginning of the
pipe. The supply flow connecting sleeve (26) is provided at the
opposite end of the pipe. The liquid heat carrier medium required
for heat transfer is fed to the flue heat exchanger via the
connecting sleeves (27, 26). The pipe loop of FIG. 8, provided
inside the flue gas pipe (28), is impinged by the enveloping flow
of the flue gases, so that a larger heat exchanger surface is
obtained for the heat transfer. The enlarged heat exchanger surface
allows optimum heat transfer from the gaseous into the liquid heat
exchanger media region.
Type of Embodiment for Flue Heat Exchanger having a
Helically-Designed Coiled Pipe
[0052] The integrated flue heat exchanger (29), as a further
effective embodiment type, may be formed by a coiled pipe (52) of
circular shape, as shown in FIG. 4. The spatial arrangement of the
pipe formed from loop to loop is brought about preferably by a
sufficiently large air gap of preferably at least 5 mm, such that
inside the flue gas discharge pipe a hollow body of round shape is
obtained. The hollow body offers the space required for
accommodating the pivotal guide plates (37) and is provided with
the return flow connecting sleeve (27) at the beginning of the
pipe. The supply flow connecting sleeve (26) is provided at the
opposite end of the pipe. The liquid heat carrier medium required
for heat transfer is fed to the flue heat exchanger via the
connecting sleeves (27, 26).
Embodiment Type of Tubular Rod Heat Exchanger with Feed Flow and
Return Flow Hollow Ring
[0053] In addition, an embodiment of a heat exchanger designed by
way of two hollow rings, as shown in FIG. 7, is provided for
connecting the tubular rods, in which case the connecting sleeve is
provided on the first hollow ring for the feed flow (26) while the
connecting sleeve for the return flow (27) is provided on the
second hollow ring. The heat exchanger is designed as a hollow body
with integrated guide plates (37), through whose inner surface area
(44) and outer surface area (45) the flue gas flows as well.
Embodiment Type of Liquid Jacket Heat Exchanger
[0054] A further embodiment type of flue heat exchangers (29) is
provided, possessing a liquid jacket (51) between two jacketing
pipes arranged inside the flue gas discharge pipe (28), through
which jacketing pipes the heat carrier liquid flows, and wherein an
air gap for flue gas guiding (45) exists between the outer
jacketing pipe surface and the inner surface of the flue gas
discharge pipe. The heat exchanger is likewise designed as a hollow
body with integrated guide plates (37), through the inner surface
region (44) of which the flue gas (22) flows as well. FIG. 6 shows
the liquid jacket heat exchanger (50).
Fastening of the Flue Heat Exchangers
[0055] Mechanical fastening of the flue heat exchanger (29) to the
flue gas discharge pipe (28) is performed preferably at the
bushings of the connecting sleeves (26, 27), which are passed
through two bores, which are located in the outer sheet (46) of the
flue gas discharge pipe (28). The connecting sleeves (26 and 27)
are fastened over the entire sleeve circumference, in particular
for fastening to the outer sheet of the flue gas discharge
pipe.
Mechanical Connections of the Heat Exchanger Components
[0056] The mechanical attachment of the feed flow and return flow
connecting sleeves, of the tubular rods on the pipe bends or hollow
rings, as shown in FIG. 4, FIG. 6, FIG. 7 and in FIG. 8, is
performed preferably by welding or hard-soldering connections.
Cleaning of Flue Heat Exchangers and Guide Plates
[0057] In the embodiment exemplified in FIG. 2, the flue gas
discharge pipe (28), in the region of the 90.degree. angle bend,
has an extensive cleaning aperture (23), through which the surfaces
of the guide plates (24) [sic], the inner surface of the flue gas
discharge pipe (28) and the interior of the outer sheet (46) can be
cleaned manually with a cleaning brush. The soot is removed by
moving the cleaning brush in and out within the scope of the
cleaning intervals required. The cleaning brush is provided with a
handle, which can preferably be adjusted stepwise or continuously
with regard to its length, such that between the cleaning aperture
and the room ceiling a sufficiently large free space exists in
order to use the cleaning brush over the entire inner surface area
from the cleaning aperture to the furnace (47). The removable lid
for closing the cleaning aperture can preferably be detached from
or fastened to the flue gas discharge pipe by means of a screw
connection.
Textured Surfaces Generate Additional Turbulences
[0058] Using textured or rough metal surfaces for the flue gas
discharge pipe (28), the flue heat exchanger (29) and the pivotal
guide plates (37), generates higher friction of the flue gas flow
(22) during transport of the media in the gaseous flow chamber as
well as on the media transfer surfaces and improves the heat
transfer from the gaseous to the liquid medium, even at low flow
rates. Textured surfaces thereby increase the efficiency of the
flue heat exchanger (29). The higher friction is caused by
turbulences, which, in turn, arises from very diverse internal flue
gas flow directions and vortexing thereof. Metal surfaces which
consist of tear-drop shaped sheets or honeycomb sheets are
particularly suitable.
Ventilation for Enhancing The Flue Gas Flow
Embodiment Example, including Pipe Fan in the Supply Air Region
[0059] An electrically-driven fan (19) is used for enhancing the
flue gas flow (22) or, respectively, the regulation thereof, in
conjunction with the pivotal guide plates (37) and their
flow-inhibiting action. The fan is designed as a pipe fan. The use
in the supply air region of the furnace (47), in which the fan (19)
presses the supply air, necessary for combustion, into the
combustion chamber, is useful as an inexpensive and efficient
solution, provided the furnace (47) is equipped with a separate
connection for the admission of supply air. Prior to opening the
furnace door, the fan (19) is switched off automatically by the
control system (5) or manually during the heating-up process, such
that, as a result of possible excessive air pressure, no flue gas
or dirt particles can escape from the furnace chamber.
Fan in Automatic Mode, Pivot Angle Setting of the Guide Plates by
Hand
[0060] In the embodiment exemplified, switching-on or switching-off
the fan (19) is done automatically by a control and regulating unit
(5), which is referred to as control system (5). Switching the fan
(19) on and off is performed as a function of the currently
prevailing flue heat exchanger temperature (9). The pivotal guide
plates (37) are automatically brought into an optimal operating
position by the control system and are pivoted, when required, into
a firing-up or cleaning position.
Fan Speed and Pivot Angle Setting in Firing-Up Mode
[0061] In practice, it has proved advantageous that during firing
up the furnace in the cold state, the optimum pivot angle (24) of
the guide plates (37) is to be set at approximately 90.degree.
while the fan speed should be in the upper range of the desired
value, so that the combustion process is performed as rapidly as
possible and with low smoke formation. In this context, the
adjustable fan speed promotes a reduction of the smoke formation
and thus a lower environmental impact.
Optimal Pivot Angle in the Heating Mode
[0062] In practice, it has also been found to be advantageous that
the angle setting (24) of the guided plates, in a fired-up furnace,
is set at an optimal pivot angle of preferably about +/-45.degree.,
in order to attain an optimal combustion and combustion output.
This pivotal angle represents a favourable operating position.
Use of the Fan Function as from a Minimum Temperature Limit
[0063] The fan (19) should preferably only be switched on
automatically by the control system (5), if the actual temperature
level (9) in the spatial region of the measuring pocket (25)
exceeds an application-dependent, measurable or calculated minimum
furnace heat exchanger temperature, in particular 50.degree. C.
Below this temperature threshold the flue heat exchanger (29) does
not supply sufficiently usable thermal energy. The calculated
switch-on temperature results from the heat storage temperature
(7), plus a temperature hysteresis, which can be specified to be
constant, or, preferably, as a variable parameter.
[0064] By means of ventilation (19) the basis is established that,
in combination with the use of the integrated pivotal guide plates
(37), a specific setting of the flue gas flow velocity (22), the
resulting combustion performance of the furnace (47) and the flue
heat exchanger (29) is attained. This optimises the efficiency of
the flue heat exchanger (29) on the basis of a favourable,
plant-specific performance range, as the combustion output is kept
constant within specific limits by way of the adjustable flue gas
flow velocity (22), maximally, however, for as long as the required
fuel is present in the combustion chamber or is refilled in time
due to advanced burn-up.
Automatic Control of the Flue Heat Exchanger Output with the
Control Variable `Fan Speed`
[0065] In the embodiment example, the rotational speed variable for
the fan (19), depending on the desired flue heat exchanger output,
as shown by way of example in FIG. 10, is performed in a stepwise
manner. The fan (19), automatically actuated by the control system
(5), is adjusted as a function of the control deviation of the flue
heat exchanger output predetermined as the desired value and
calculated from the actual output value. The control system
operates such that the rotational speed variable is increased, if
the heat exchanger output is too low and that, conversely, the
rotational speed variable is reduced accordingly, if the heat
exchanger output is too high.
Fan Actuation in Manual Mode or Combined with Automatic
Operation
[0066] In a further embodiment type, the fan can be actuated in
manual mode by a speed which can be adjusted stepwise or
continuously. Activation of the fan (19) with constant rotational
speed or a variable rotational speed setting is in this case done
on the basis of the experience gained by the operator. Similarly,
the execution modes `manual` or `automatic operation` may be
selected manually, if required, and combined as a result thereof.
Manual operation may be useful, if one wishes to avoid the higher
costs of a control system, or if the actuator efficiencies of
automatic regulation are not met. The situation may arise, if, for
example, too much or too little fuel was fed, or if the furnace
door is opened during furnace operation, whereby the control system
can not work optimally.
Further Embodiment Types and Installation Sites of Ventilation
[0067] Lateral installation on the flue section or in the chimney
region as injector-fan (19) seems useful, as in this case the fan
(19) presses additional air into the flue gas discharge region,
thereby entraining the flue gas from the furnace (47).
[0068] The installation in the flue gas discharge pipe, preferably
as far away as possible from the firing chamber, because of the
lower temperatures, is likewise possible.
[0069] The fan (19) may furthermore be fitted on the chimney as a
chimney crest fan.
Further Embodiment Types of the Flue Heat Exchanger Control Systems
and Combinations thereof
Controlling the Flow Rate with the Control Variable `Fan Speed`
[0070] In embodiment types that require a defined flow rate,
preferably the execution mode with the control variable `fan speed`
should be selected. A possible application in combination with a
device for reducing soot particles in furnaces seems useful. These
may require ventilation in relation to an adjustable flue gas flow
and thus provide a useful combination possibility of soot particle
filtration using the ventilation according to the invention.
Automatic activation of the fan (19) is performed by the control
system (5) as a function of the desired flow velocity (22) in the
flue gas pipe (28). In this context as well, a variable fan speed
is used as the control variable at the control system output. This
control variable is obtained as a function of the control
deviation, predetermined as the desired value, minus the control
deviation calculated from the actual flow rate, of the flue gas
flow velocity (22) in the flue heat exchanger (29). The control
system intervenes in such a manner that the desired rotational
speed value serving as the control variable is increased, if the
flue gas flow velocity is too slow and that, on the other hand, the
desired rotational speed value is reduced accordingly if the
flue-gas flow velocity is too high. Controlling the fan speed
without a closed-loop control circuit of the flow velocity, in
particular without actual flow value collection, is likewise
possible for reasons of simplicity.
Control of Flue Gas Temperature with the Control Variable `Fan
Speed` and/or `Angular Position of the Guide Plates`
[0071] For embodiment types requiring a specific or minimum flue
gas temperature (9), the control variable `fan speed` and/or
"angular position of the guide plates" can likewise be applied. A
possible application may arise, if the temperature at the chimney
crest may not fall below a minimum chimney temperature of
preferably 55.degree. C., in order to avoid undesirable sooting of
the chimney. Automatic activation of the fan (19) is performed by
the control system (5) as a function of the desired flue gas
temperature (9) measured in the flue gas pipe (28) or measured
outside on the flue gas pipe as the flue gas pipe temperature (9).
The determination of the control variable is obtained as a function
of the temperature predetermined as the desired value, minus the
control deviation determined from the actual temperature level (9).
The control system intervenes in such a manner that the desired
rotational speed value serving as the control variable is increased
continuously or stepwise, if the temperature is too low and that,
conversely, the desired rotational speed value is reduced
accordingly, if the temperature is too high. The control variable
`angular position (24) of the guide plates` acts such that the
angle settings (24) of the guide plates are to be increased
continuously or stepwise, if flue gas temperatures (9) are too low,
in order to increase the flue gas flow (22) and that, conversely,
the angle settings (24) of the guide plates are to be reduced, if
the flue gas temperatures (9) are too high. Both control variables
thus complement each other in terms of their desired effect and can
be combined.
Controlling the Flow Velocity with the Control Variable `Pivot
Angle of the Guiding Plates`
[0072] If no rotational speed control or adjustment of the fan
speed is possible in ventilation applications, an automatic pivot
angle setting of the guide plates can be used. The automatic pivot
angle setting (24) of the guide plates is performed by the control
system (5), which adjusts a servo drive means in terms of the
position of its angle of rotation. In this case, the servo drive
means with its shaft outlet is mechanically connected to one of the
guide plate shafts on the rotary lever 1 or rotary lever 2 in such
a manner that the current position of its angle of rotation
determines the pivot angles of the guide plates. The angle setting
is performed as a function of the control deviation predetermined
as the desired flow value and minus the control deviation
determined from the actual flow value of the flue gas flow velocity
(22) in the flue heat exchanger (29) such that the guide plate
angle (24) serving as the control variable is increased, if the
flue gas flow velocity (22) is too low and that, conversely, the
guide plate angle (24) is reduced accordingly, if the flue gas flow
velocity is too high.
Control of the Flue Heat Exchanger Output with the Control Variable
`Pivot Angle of the Guide Plates`
[0073] If no rotational speed control or adjustment of the fan
speed is possible in ventilation applications, an automatic pivot
angle setting of the guide plates can be used. The automatic pivot
angle setting (24) of the guide plates is performed by the control
system (5), which adjusts a servo drive means in terms of the
position of its angle of rotation. In this case, the servo drive
means with its shaft outlet is mechanically connected to one of the
guide plate shafts on the rotary lever 1 or rotary lever 2 in such
a manner that the current position of its angle of rotation
determines the pivot angles of the guide plates. The angle setting
is performed as a function of the control deviation predetermined
as the desired output value and minus the control deviation
determined from the actual output value of the flue heat exchanger
output such that the guide plate angle (24) serving as the control
variable is increased, if the heat exchanger output is too low and
that, conversely, it is reduced accordingly, if the heat exchanger
output is too high.
Control of the Flue Heat Exchanger Output or the Flow Velocity with
the Control Variable `Fan Speed` and a Speed-Correcting Value
Derived from the Current Pivot Angle Position of the Guide
Plates
[0074] To increase the control precision in the control of the flue
heat exchanger output or the flow velocity with the control
variable `fan speed` a speed correction value is preferably added
to the speed control variable or is multiplied as a factor which is
determined as a function of the current angular position (24) of
the guide plates. The determination of this correction factor can
be calculated by using a mathematical formula, or may be determined
on the basis of experience gained, or which results from an
empirical function and is listed in a table.
Coupling of Heat Circuits in Parallel According to FIG. 1
[0075] The embodiment exemplified connects the solar heating
circuit (1) by coupling in parallel to the furnace heating circuit
(2) by using solar liquid as the heat carrier. Since the current
thermal output to be utilised of both equal heat sources should be
as high as possible, both heating circuits can be activated
simultaneously, provided sufficient thermal energy is available in
each case. Each heating circuit (1, 2) has its own circulation pump
(10, 11). The parallel heating circuits can thus be activated by
the control system (5) independently of one another. Stepwise
variable pump speeds can be set for the circulation pumps (10, 11)
by manual adjustment during start-up.
[0076] The heating circuit coupling in parallel for heat transfer
into a heat accumulator (3) is performed in the embodiment
exemplified by a heat exchanger (4) via independently-controlled
media flows (14, 15 and 31). The control logic and the hydraulic
system structure form a co-acting functional unit.
[0077] In addition, the media circuit resistances or media flow
rates (14, 15) can be adjusted separately for each heating circuit
(1, 2) by way of adjusting the flow rate limiter (20, 21)
associated with each heating circuit (1, 2). Adjusting the media
circuit resistances (20, 21) is likewise performed by manual
adjustment during start-up.
[0078] Switching on and off of the actuators of the circulation
pump (10) and the circulation pump (11) is performed in a
temperature-dependent manner by means of the control system (5),
which emits a signal (17) for activating the circulation pump (10)
as well as signal (18) for activating the circulation pump (11).
The control system (5) activates the actuators of the parallel
heating circuits as a function of the media temperatures of the
heat sources (8, 9) and the media temperature in the heat
accumulator (7).
[0079] In this context, especially the following 4 operating modes
are provided:
[0080] Disabling heating circuits 1 and 2
[0081] Activating heating circuit 1
[0082] Activating heating circuit 2
[0083] Activating heating circuits 1 and 2
[0084] If only one heat source is activated, the check valves (12
or 13) prevent an undesired flow of media (14 and 15) between the
parallel heating circuits (1 or 2).
[0085] The heating circuit (2) is activated by switching on the
actuator (11) or by the control signal (19). The open check valve
(13) causes the flow of the media (15) and (16). Since the check
valve (12), located in the heating circuit 1 (1), is closed by the
inactive actuator (10), no media flow (14) occurs.
[0086] The heating circuit (1) is active when the actuator (10) is
switched on and the check valve (12) is forcibly opened by the
built-up pressure of the actuator (10), thereby causing the flow of
the media (14) and (16). The control system (5) activates the
actuator (10) by switching on the control signal (18). Since the
check valve (13), located in the heating circuit 2 (2), is closed
by the inactive actuator (11), no media flow (15) occurs.
Start-Up Requirements
[0087] For safety reasons, the circulation pumps (10) and/or (11)
are only turned on, if the maximum water temperature in the
accumulator (7) is not exceeded. The measurable maximum temperature
level does, in particular, not exceed 95.degree. C.
[0088] To set the optimum operating parameters, a separate
switchable, variable-speed pump (10, 11) is used for each heating
circuit (1, 2), having e.g. three manually-adjustable base speeds
for the media flow setting. In addition, the media circuit
resistances can be set by adjusting the setting of the flow rate
limiter (20, 22) associated with each heating circuit, so that,
when combined, the media flow rates can be set independently from
one another.
[0089] The optimum operating parameters for setting the flow rate
and flow output of the parallel heating circuits during start-up
were carried out on the basis of plant-specific and operational
requirements. The media flows of the heating circuits (1, 2) are
preferably to be set at 1,5 litres/minute, in which case the two
circulation pumps (10, 11) are preferably to be set at the lowest
output level at about 40 watt power consumption. The minimum output
level includes also the overall lowest energy consumption for the
necessary media transport for heat transfer. An optimal setting of
the media flow exists, in particular, if the media flows of the
heating circuits are approximately of the same order of magnitude.
The flow rates of the circulation pumps should in this context
likewise have approximately the same values. During operation it
has been shown, in particular, that this selected setting of the
media flows prevents an undesired temperature influence of the
respectively switched-on heating circuit on the isochronously
switched-off heating circuit.
Activation of the Heat Circuits as a Function of the Associated
Actual Temperature Levels
[0090] In the embodiment exemplified, the control system (5)
activates the heating circuits (1 and/or 2) on the basis of a
temperature comparison between the parallel heating circuits, such
that that heating circuit or those heating circuits are switched
on, which has/have an actual temperature level (8 and/or 9) higher
than the heat storage temperature (7). In order to implement the
embodiment exemplified, it is necessary to install an actual
temperature level transmitter (7) in the lower region of the heat
accumulator (3) or in the local region of the heat exchanger
(4).
Activation of Heating Circuit 1
[0091] The actual temperature level (8) captured in the parallel
heating circuit 1 is compared to the temperature in the lower heat
accumulator region (7). If the feed temperature of the parallel
heating circuit 1 (8) is higher than the temperature in the lower
heat accumulator region (7), the circulation pump (10) of the
parallel heating circuit 1 (1) is switched on by the control
variable (17) and the heating circuit (14) and (16) is activated.
If the feed temperature of the parallel heating circuit 1 (8) is
lower than the temperature in the lower accumulator region (7), the
circulation pump (10) of the parallel heating circuit 1 (1) is
switched off by the control variable (17) and the heating circuit
(14) and (16) is not active.
Activation of Heating Circuit 2
[0092] The actual temperature level (9) captured in the parallel
heating circuit 2 is compared to the temperature in the lower heat
accumulator region (7). If the feed temperature of the parallel
heating circuit 2 (9) is higher than the temperature in the lower
heat accumulator region (7), the circulation pump (11) of the
parallel heating circuit 2 (2) is switched on by the control
variable (18) and the heating circuit (15) and (16) is activated.
If the feed temperature of the parallel heating circuit 2 (9) is
lower than the temperature in the lower accumulator region (7), the
circulation pump (11) of the parallel heating circuit 2 (2) is
switched off by the control variable (18) and the heating circuit
(15) and (16) is not active.
Simultaneous Activation of Heating Circuits 1 And 2:
[0093] Both circulation pumps (10 and 11) are active
simultaneously, if both actual temperature levels (8 and 9) are
higher than the temperature in the lower heat accumulator region
(7). In this case, both heat circuits (1 and 2) make an appreciable
contribution to heat generation and the current outputs of the heat
sources (1, 2) add up. For this reason, the embodiment exemplified
is suited, in particular, for coupling heating circuits, if the
highest possible level of thermal output is to be attained.
[0094] Due to different applications, a plurality of embodiment
types of the heating circuits coupled in parallel arise.
Embodiment Type with Activation of Only One Heat Source of the
Heating Circuits 1 or 2
[0095] The heat sources 1 and 2 are used interchangeably. The heat
source having a higher media temperature (8 or 9) in comparison to
the media temperature in the heat accumulator (7) is used. Only one
of the heating circuits (14 or 15) can be activated simultaneously
in order to prevent undesired temperature transfers between the
heating circuits (14 or 15). The media circuit (14 or 15), which
has the higher actual temperature level (8 or 9), is activated by
one of the two circulation pumps (10 or 11). This type of
embodiment is suitable for applications, where heat transfer must
not take place under any circumstances between the heat sources, in
particular for applications, where no thermal energy, e.g. from a
furnace heat source, may be transferred to solar modules, given
that the solar modules are fitted externally on the roof. This type
of embodiment thus totally prevents an energy balance between the
heating circuits.
An essential prerequisite for the independent activation of the
heating circuits (1, 2) is the installation of the circulation
pumps (10) and (11), shown, including the check valves (12) and
(13) in the hydraulic diagram shown in FIG. 1. The active
circulation pump (10) can only open the check valve (12), while the
check valve (13) remains closed in this case. The active
circulation pump (11), however, can only open the check valve (13),
while, in reverse, the check valve (12) remains closed in this
case.
Embodiment Type of Furnace Heating Circuit as a Secondary
System
[0096] In this type of embodiment, the furnace heating circuit (2)
is used as a secondary system for heating and hot water generation.
In this context, the heating circuit (1) forms the primary system
coupled in parallel. The embodiment is suited, in particular, for
coupling heating circuits, which are supplied by a
continuously-available energy source (oil heating, gas heating,
heat pumps, long-distance heating, etc.) of heating circuit 1 (1)
as well as by a discontinuously-operating energy source (chimney
oven, tiled stove, solar heating etc.) of heating circuit 2 (2).
Control (5) may be performed independently of the existing control
of the primary system. For this reason, the embodiment exemplified
is particularly suitable for plant expansions, wherein an
additional furnace heating circuit is retrofitted, without having
to adapt or modify the existing control system of the primary
system. Furthermore, applications are advantageous, wherein the
temperature may not fall below a specific level. Especially for
heating drinking water this procedure is useful, if the temperature
in a hot water accumulator is to have a temperature of preferably
at least 60.degree. C., in order to ensure the required destruction
of legionella. The desired temperature level (6) constitutes the
threshold of the switch-on temperature for the heat supply of the
heating circuit (1). The desired temperature level may be a
measurable constant or a variable value.
Activation of Heating Circuit 1 (1)
[0097] If the actual temperature level (7) is lower than the
desired temperature level (6), heat supply is performed via the
heating circuit 1 (1), which is activated by the control signal
(17) and the actuator (10) associated therewith. This causes the
media flow to be conducted by the media circuits (14) and (16). The
heat supply of the basic system (1) is switched off, if the actual
temperature level (7) is higher than the desired temperature level
(6).
Activation of Heating Circuit 2 (2)
[0098] The actual temperature level (9) recorded at the parallel
heating circuit 2 is compared to the desired temperature (6). If
the actual temperature level (9) is higher than the desired
temperature (6), the actuator (11) of the parallel heating circuit
2 (2) is switched on by actuating the actuator (18), thus
activating the heating circuit (15) and (16). The parallel heating
circuit 2 is switched off at a temperature which is below the
predetermined desired temperature (6). The energy contributions
occurring above the desired temperature (6) are therefore taken
over by the parallel heating circuit 2 (2). If the actual
temperature level (7) is available to the control unit (5) for
temperature comparison with the actual temperature level (9), this
procedure would be more effective than tapping off at the desired
temperature (6) and would thus be more advantageous in its
application.
Embodiment Type of Furnace Heating Circuit as Primary System
[0099] As an alternative, the furnace heating circuit (2), serving
as primary system, may be used for heating and hot water
production. The heating circuit (1) constitutes in this case the
secondary system, coupled in parallel. This embodiment type is
suited particularly for coupling of heating circuits, which are
supplied by a continuously-available furnace heat source (tiled
stove, chimney oven, pellet heating etc.) of heating circuit 2 (2)
as well as by a discontinuously-operating energy source (solar
heating etc.) of heating circuit 1 (1). The desired temperature
level (6) constitutes the threshold of the switch-on temperature
for the heat supply of the furnace heating circuit (2). The desired
temperature level may be a measurable constant or a variable
value.
[0100] Activation of furnace heating circuit 2 (2): If the actual
temperature level (7) in the heat accumulator (3) is lower than the
desired temperature level (6), heat supply is performed via the
heating circuit 2 (2), which is activated by the control signal
(18) and the actuator (11) associated therewith. This causes the
media flow to be conducted by the media circuits (15) and (16). The
heat supply of the basic system (1) is switched off, if the actual
temperature level (7) is higher than the desired temperature level
(6).
[0101] Activation of heating circuit 1 (1): The actual temperature
level (8) recorded at the parallel heating circuit 1 is compared to
the desired temperature (6). If the actual temperature level (8) is
higher than the desired temperature (6), the actuator (10) of the
parallel heating circuit 1 (1) is switched on by actuating the
actuator (17), thus activating the heating circuit (14) and (16).
The parallel heating circuit 1 is switched off at a temperature
which is below the predetermined desired temperature (6). The
energy contributions occurring above the desired temperature (6)
are therefore taken over by the parallel heating circuit 1 (1). If
the actual temperature level (7) is available to the control unit
(5) for temperature comparison with the actual temperature level
(8), this procedure would be more effective in comparison with
tapping off at the desired temperature (6) and would thus be more
advantageous in its application.
ADVANTAGES OF THE INVENTION
[0102] The use of pivotal integrated guide plates, including
ventilation, reduces the heat losses of the furnace with respect to
thermal energy, which enters into the chimney without being
utilised, as higher combustion temperatures occur in the furnace
and a considerably higher exploitation of the flue gas waste heat
takes place than in the known flue heat exchangers. The efficiency
improvement is based on higher friction of the flue gases in the
gaseous media region. The pivotal guide plates deflect the flue gas
as a mechanical obstacle, thereby generating a turbulent flue gas
flow, which produces the increased friction. Use of the
ventilation, in conjunction with the pivoted guide plates, creates
increased pressure in the flue gas pipe, increased flow velocity,
stronger turbulences and, therefore, further additional friction in
the gaseous media chamber, thereby increasing once again the
efficiency of the entire furnace.
[0103] The increase in efficiency is demonstrated graphically in
FIG. 9 by way of two output curves (55, 56), which were recorded
successively in time and which are shown isochronously in relation
to one another. Two test runs were carried out with, in each case,
2 kg of pinewood in a pre-heated chimney furnace. The wood supply
was burnt up per test run in a time period of about 50 minutes and
the flue heat exchanger outputs (53) occurring in the course
thereof measured by sensor means (32, 33, 34) and calculated
time-cyclically with the aid of the control system (5). The flue
heat exchanger was arranged externally around the flue gas pipe and
the fan was switched on or off manually. The data recordings for
both test runs took place at a 3-minute time interval (54). The
burn-off process for test run 2 was so adjusted by manually-set
supply of the combustion air that it resulted in approximately the
same burn-off period of the wood supply as test run 1, in order to
bring about the necessary comparability of the output measurements
in a defined time frame with combustion being the same. For
recording the measurement series 1 (55) the fan was switched on for
the entire measuring period at maximum or, respectively, constant
output (20 watt), the 4 guide plates, installed in the flue heat
exchanger, being set at the same guide plate angle of +45.degree..
When recording the measurement series 2 (56), the fan was switched
off and the angle setting of all guide plates was set at
90.degree., such that the flue gases were able to escape without
being affected in the flue gas pipe. The increased output with
ventilation and guide plate angle setting of 45.degree., under the
conditions shown, minus the fan current losses, was approximately
31,5% or an about 250,5 W higher flue heat exchanger output.
[0104] In addition, the heat exchanger efficiency is significantly
increased, if a larger effective heat exchanger surface from the
gaseous into the liquid media space is provided, which is created,
if the heat exchanger is impinged by an enveloping flow in the
interior of the flue gas furnace pipe. This measure attains
doubling of the heat exchanger surface, which allows to expect
double the flue heat exchanger output.
[0105] A preferably textured or non planar guide plate surface
enhances the increase in efficiency, as further turbulences or
vortexes arise in the gaseous media space.
[0106] The apparatus and process according to the invention are
suited, in particular, for a combination with means for reducing
soot particles in furnaces which require additional ventilation for
adjusting a constant flue gas flow in order to optimise efficiency.
The use of soot particle filters will increase significantly in
future, as the installation of such filter systems is prescribed by
law for furnace systems in Germany while observing specific
deadlines.
[0107] Due to the adjustability of the flue gas volume flow by
specifying a measurable or calculated desired speed value for the
flue gas fan in conjunction with the adjustability of the pivotal
guide plates, combustion control is possible when using the flue
gas pipe heat exchanger.
[0108] FIG. 10 shows the measurement graph of an output control
using the control variable `fan` in `On` or `Off` positions. The
fan, which served to control the flue heat exchanger output, was
operated constantly at maximum nominal rotational speed for this
measurement series and was switched on or off when defined output
limits were exceeded or not attained. The control principle worked
such that the oxygen supply for the combustion process was
increased, if the flue heat exchanger output was too low, and,
conversely, was reduced by way of the fan function, if the output
was too high. The current actual output value resulted from the
current heat exchanger media flow and the temperature difference
between the feed- and return flow temperature of the flue heat
exchanger circuit. The recorded data reflect a testing pattern from
lighting the fire, starting with measurement 1, and ending with
measurement 136, with which the combustion process and the
measuring value recording were systematically concluded due to a
lack of firewood. The output thresholds for controlling the
ventilation were determined empirically during furnace operation on
the basis of installation-specific heat exchanger outputs and
defined as follows:
[0109] P_Min_UG: 240 watt, Lower Output Threshold, including
hysteresis for switching off the fan
[0110] P_Min_OG: 300 watt, fan switch-on power
[0111] P_Max_UG: 540 watt, Lower Output Threshold of fan switch-off
power, including hysteresis
[0112] P_Max_OG: 600 watt, Upper Output Threshold of fan switch-off
power. The recorded binary signal, `Fan_On`, shows the fan status
which was determined by the control system in the course of the
measurements in relation to the currently measured flue heat
exchanger outputs and the thresholds associated therewith.
Regulating deviations of about +/-300 watt result from the inertia
of the control path, in particular during the slow cooling off
process after switching off the fan. The efficacy of the control
system is clearly visible, as the output increases after
ventilation switch-on and, inversely, decreases after ventilation
switch-off and the mean values of the outputs within the upper
thresholds are in the desired value range of between 540 and 600
watt.
[0113] For hot water production or for heating backup in domestic
heating systems, applications are advantageous, which serve to
equip new heating systems or for system expansion or
modernisation.
[0114] The integrated flue heat exchanger can be employed for use
with all known furnace heat sources. In particular, the connection
of open fireplaces, chimney ovens, tiled stoves, pellet stoves or
conventional ovens is possible.
[0115] For coupling in parallel to the furnace heating circuit, the
known heat sources for buildings, such as, e.g., oil heating
systems, gas heating systems, long-distance heating systems, heat
pumps or thermal solar plants can be used.
[0116] The use of the parallel heating circuits has a particularly
advantageous effect on couplings between solar installations and
ovens, as renewable energies are used optimally in combination.
Ideally, solar energy is used during the day with subsequent
supplementary evening and night use of an oven, using the renewable
fuel, wood.
[0117] By using only one heat exchanger for the transfer of thermal
energy of the parallel heating circuits into a heat accumulator and
the use of a solar carrier liquid serving as heat transfer medium,
direct media coupling of the flue heat exchanger to a thermal solar
installation is possible.
[0118] The independent activation and adjustability of the media
flows in the parallel heating circuits allows the necessary degrees
of freedom for a smooth start-up and fast optimisation of the
heating circuits and ensures stable operating conditions.
[0119] The modular design of the furnace heating circuit allows
simple, space-saving and cost-effective construction. The equipment
selection can be carried out by means of pre-assembled standard
products from thermal solar technology.
[0120] The use of a solar heat transfer liquid results in
temperature reserves concerning the utilisation of the installation
until the boiling point in the furnace heating circuit is attained.
As the boiling point of the solar heat carrier liquid is at about
150.degree. C., the latter will not vaporise at arising
temperatures between 100.degree. C. and 150.degree. C. In addition,
the solar heat carrier liquid of the apparatus according to the
invention can be heated to about 300.degree. C. without any
problem, without it decomposing.
LIST OF REFERENCE NUMERALS
[0121] (1) Parallel heating circuit 1 with heat source 1, e.g.
thermal solar plant [0122] (2) Parallel heating circuit 2 with heat
source 2, e.g. chimney furnace [0123] (3) Heat accumulator [0124]
(4) Heat accumulator [0125] (5) Control system [0126] (6) Desired
temperature level heating circuit 1 [0127] (7) Temperature sensor
heat accumulator [0128] (8) Temperature sensor parallel heating
circuit 1, media temperature at heat source 1 [0129] (9)
Temperature sensor parallel heating circuit 2, media temperature at
heat source 2 (flue gas temperature or flue gas pipe temperature)
[0130] (10) Actuator for parallel heating circuit 1, in particular
circulation pump with three different speed settings or continuous
adjustability [0131] (11) Actuator for parallel heating circuit 2,
in particular circulation pump with three different speed settings
or continuous adjustability [0132] (12) Check valve for the control
of the media flow, parallel heating circuit 1 [0133] (13) Check
valve for the control of the media flow, parallel heating circuit 2
[0134] (14) Media flow direction parallel heating circuit 1 active
[0135] (15) Media flow direction parallel heating circuit 2 active
[0136] (16) Media flow direction in active parallel heating circuit
1 or active parallel heating circuit 2 [0137] (17) Actuator control
parallel heating circuit 1 [0138] (18) Actuator control parallel
heating circuit 2 [0139] (19) Electrically-driven fan, control
variable `fan speed` [0140] (20) Flow rate limiter for the heating
circuit 1 [0141] (21) Flow rate limiter for the heating circuit 2
[0142] (22) Flue gas flow in the gaseous heat carrier medium, flue
gas flow velocity [0143] (23) Cleaning aperture including a lid and
wing screw [0144] (24) Adjustable angular range of the pivotal
guiding plates, control variable `angular position of guide plates`
[0145] (25) Measuring pocket for temperature sensor [0146] (26)
Feed flow, VL [0147] (27) Return flow, RL [0148] (28) Flue gas
discharge pipe, including wall connection [0149] (29) Flue heat
exchanger, including all designs [0150] (30) Ventilation valve
[0151] (31) Connection possibility for further parallel heat
sources [0152] (32) Sensor flow rate measurement for output
calculation [0153] (33) Feed flow temperature for output
calculation [0154] (34) Return flow temperature for output
calculation [0155] (35) Rotary lever 1 for pivoting the guide
plates [0156] (36) Rotary lever 2 for pivoting the guide plates
[0157] (37) Pivotal guide plates, including a pivoting axis
provided in the centre thereof [0158] (38) Hinges with a centre of
rotation for pivoting the guide plates [0159] (39) View of section
A: Guide plate angle=0.degree. [0160] (40) View of section A: Guide
plate angle=90.degree. [0161] (41) Pivotal lever rod 1 for
simultaneous or uniform adjustment of the guide plates [0162] (42)
Pivotal lever rod 2 for simultaneous or uniform adjustment of the
guide plates [0163] (43) Connecting rod for synchronous pivoting
function of all guide plates [0164] (44) Space for flue gas flow in
the interior of the heat exchanger [0165] (45) Space for flue gas
flow between the inner surface of the flue gas discharge pipe and
the outer surface of the heat exchanger [0166] (46) External metal
sheet flue gas discharge pipe [0167] (47) Furnace [0168] (48)
Switching valve heating circuit 1 [0169] (49) Switching valve
heating circuit 2 [0170] (50) Flue heat exchanger, designed with
internally inserted liquid jacket heat exchanger [0171] (51) Liquid
jacket between exterior and interior wall pipe [0172] (52) Flue
heat exchanger, designed with internally inserted coiled pipe
[0173] (53) Flue heat exchanger output in watt [0174] (54)
Measurements: 3 min time cycle [0175] (55) Measurement series 1:
Guide plate angle 45.degree. with ventilation [0176] (56)
Measurement series 2: Guide plate angle 90.degree. without
ventilation [0177] (57) Mechanical connection point for a servo
drive means or rotary drive means on the pivoting axis of the guide
plates
* * * * *