Patent Application
20130092105
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.
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.
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.
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.
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
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
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.
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.
Manual setting by the operator or automatic setting via a control system is not provided.
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.
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.
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 (
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 (
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.
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.
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.
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.
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.
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.
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.
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).
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.
Embodiment types are possible which use the chimney furnace installation (2) as the basic system.
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.
2 mechanical temperature display devices
Mechanical pressure gauge for pressure display
Hand-operated shut-off valves
Overflow valve with blow-off system in the event of excessive pressure
Connection for an excess pressure storage means
Excess pressure storage means
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.
Function principle: Integrated flue heat exchanger with pivotal guide plates
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° to 90°, 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° towards 90°, 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
The guide plates (37) used in the embodiment exemplified according to
A first mechanical connection is brought about by a pivoting lever rod 1 (41), as shown in
A second mechanical connection is brought about by a further pivoting lever rod 2 (42), as shown in
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
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° to +90°.
Since the angle setting of the guide plates of −90° or 90°, as shown in
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.
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° pipe bends, as shown in
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
In addition, an embodiment of a heat exchanger designed by way of two hollow rings, as shown in
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.
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.
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
In the embodiment exemplified in
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.
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.
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.
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° 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.
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°, in order to attain an optimal combustion and combustion output. This pivotal angle represents a favourable operating position.
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° 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.
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.
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
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.
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).
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.
The fan (19) may furthermore be fitted on the chimney as a chimney crest fan.
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.
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° 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.
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.
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.
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.
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.
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.
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.
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).
In this context, especially the following 4 operating modes are provided:
Disabling heating circuits 1 and 2
Activating heating circuit 1
Activating heating circuit 2
Activating heating circuits 1 and 2
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).
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.
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.
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° C.
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.
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.
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).
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.
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.
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.
Due to different applications, a plurality of embodiment types of the heating circuits coupled in parallel arise.
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
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° 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.
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).
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.
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.
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).
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.
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.
The increase in efficiency is demonstrated graphically in
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.
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.
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.
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.
P_Min_UG: 240 watt, Lower Output Threshold, including hysteresis for switching off the fan
P_Min_OG: 300 watt, fan switch-on power
P_Max_UG: 540 watt, Lower Output Threshold of fan switch-off power, including hysteresis
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.
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.
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.
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.
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.
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.
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.
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.
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° C., the latter will not vaporise at arising temperatures between 100° C. and 150° C. In addition, the solar heat carrier liquid of the apparatus according to the invention can be heated to about 300° C. without any problem, without it decomposing.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 023 381.1 | Jun 2010 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE2011/001141 | 5/31/2011 | WO | 00 | 12/26/2012 |
