CH663083A5 - BOILER. - Google Patents

Description

The invention relates to a boiler, in particular for space heating purposes, according to the preamble of claim 1.

Conventional boilers, such as those used for building heating and hot water preparation, are designed in such a way that they reach their nominal output when the greatest heat demand occurs during operation, i.e. on cold winter days.

In order to achieve the best possible use of the heat of combustion, the burner and the boiler are matched to one another in such a way that the flue gas has the lowest possible temperature when leaving the boiler and entering the chimney. However, this must not be so low that it leads to the chimney staining. In practice, therefore, the boiler outlet temperature of the flue gas at full boiler output should be in the region of 150 ° C (approx. 420 K).

When the heat requirement is low, the burner of such a boiler is switched on and off periodically. However, the longer the switch-off periods, the more the boiler's efficiency drops. In order to obtain an improvement in efficiency, the burner's heat supply has been adapted to the respective heat requirement as far as possible and burners have been built with several, usually two power levels, which can therefore be operated depending on the load.

If the burner is now operated with a lower output when heat is low, the flue gas temperature drops at the end of the boiler.

Since the flue gas outlet temperature must not fall below a certain value, the boiler must be designed in such a way that it reaches the stated flue gas temperature even when the burner is operating at low output. If the burner is operated at high output, the flue gas outlet temperature significantly exceeds the desired, economical temperature of 150 to 160 ° C, so that the efficiency of the boiler deteriorates again when the burner output is high.

In view of this problem, boilers with two combustion chambers and two burners were built, of which only one was operated with low heat requirements, i.e. the boiler was operated at half load. In this way, an optimal exhaust gas temperature could be approximated better than before. The technical effort for this was very high.

Based on this prior art, the invention has for its object to improve a boiler of the type mentioned in such a way that it can be operated with good efficiency at both high and low burner output, so in both cases the flue gas an outlet temperature from the boiler which deviates as little as possible from the optimal temperature of 150 to 160 ° C.

According to the invention, this object is achieved by the characterizing features of claim 1.

Here, the size of the inner surface of the boiler, which is exposed to the flame and / or the flue gas of the burner and serves for heat exchange, can be matched to the required output of the burner without great technical effort

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be adjusted in such a way that the optimum flue gas outlet temperature is at least approximated for each burner output. In this way, a reduced flue gas throughput is offset by a reduced heat transfer surface of the boiler during burner operation, so that the flue gas outlet temperature of the boiler does not drop to an unacceptable extent.

The principle according to the invention can also be applied analogously to the aforementioned boilers with two combustion chambers and burners by further developing at least one of the two boiler halves according to the invention.

For all burner outputs, the boiler according to the invention approximately achieves the efficiency of a boiler that is dimensioned precisely for the burner output present in each case. The boiler according to the invention can thus always be operated with the best efficiency.

The boiler according to the invention is at least approximately as economical to operate in the partial-load ranges as at nominal load, so that it is possible to adapt the burner output as precisely as possible to the heat requirement in each case and thereby to prevent the burner from being switched on and off too often, which reduces efficiency.

The boiler according to the invention is therefore not only suitable for economically supplying the heating output of a building heating system, which may differ over a year (possibly with hot water preparation). It is e.g. Also suitable for heating buildings and systems that have a fluctuating heat requirement. For example, it is possible to design the boiler for heating a restaurant in such a way that an adjoining room, hall or the like can be heated up in a short time, without having to accept a loss in efficiency during normal heating operation.

The flame and / or flue gas path can be changed, for example, by means of sliders,

Flaps or the like. Parts of the flue gas path are switched on or off or the flue gas path is lengthened or shortened.

Another possibility is that the combustion chamber, which is normally fully used, is only partially used to a greater or lesser extent. This training is particularly recommended when there is no reversal of the flue gas flow in the combustion chamber, in particular in the case of cast sectional boilers.

Both options can also be combined with each other.

In any case, it is achieved according to the invention that a correspondingly smaller heated boiler surface is available with reduced burner output.

According to a further embodiment of the invention, the nozzle supporting the flame, which extends from the main part of the burner, is extended to a neck, the amount by which this neck projects into the combustion chamber of the boiler being adjustable according to the burner output.

The further the burner is pushed with its neck into the combustion chamber, the more the length of the combustion chamber affected by the flames is shortened and the smaller the amount of heat that can be given off in the combustion chamber to the heat transfer medium. In the case of conventional cast sectional boilers, the length of the flue gas path through the trains surrounding the combustion chamber is also shortened. At the lowest power, the burner with its neck is thus fully retracted into the combustion chamber, while the neck is moved out of the combustion chamber to achieve the nominal power, so that the flame of the burner in this case then the whole

Brushed combustion chamber length.

Preferably, with the adjustment of the burner, a disc surrounding the neck near its end and approximately filling the cross section of the combustion chamber is adjusted,

which is preferably worn by the neck. In this case, the disc separates the section of the combustion chamber that is not used during part-load operation from the section used and ensures that the flue gas takes the desired path in the boiler.

The last refinements of the invention concerned a burner with an elongated neck which can be moved more or less far into the combustion chamber, the end wall of which supports the burner and is stationary.

However, it is also possible to attach a conventional burner, the flame opening of which is located directly behind the end wall of the combustion chamber that supports it, on such end wall, which in turn can then be moved into the combustion chamber according to the invention.

The play between the movable end wall and the wall of the combustion chamber, which is required for the functional movement of the end wall, can e.g. be sealed by means of a steel brush field carried by the circumference of the movable end wall or by means of asbestos seals.

Instead of the movable combustion chamber end wall carrying the burner or in addition to this, according to a further embodiment of the invention, the end wall opposite the burner can be designed to be movable into and out of the combustion chamber, the play required to ensure the trouble-free movement in the same way can be sealed.

The advantage of this embodiment is that an unmodified burner can be attached in a stationary manner, so that flexible fuel supply lines are not required, as in the last-mentioned exemplary embodiment. In this respect, the training according to claims 2 and 3 is currently preferred.

A particularly simple embodiment of the invention is that instead of the end wall opposite the burner, a baffle wall arranged inside the burner and facing the burner is adjustably arranged so that it can be moved into and out of the burner. This baffle is preferably dimensioned such that it approximately covers the entire internal cross section of the combustion chamber, as is also the case with the above-mentioned pane.

In the case of a boiler design with a plurality of flue gas flues connected in parallel to the combustion chamber, as is usually used in welded steel boilers, it is advantageous to design at least one of the flues and at most all but one of them to be shut off. If, during part-load operation of the burner, a lower throughput of flue gas occurs than under full-load operation, switching off one or more trains can ensure that the trains that are still in operation are operated with such a throughput of flue gas that corresponds to the target end temperature at the outlet of the flue gas flues and thus the Boiler supplies.

In this context, “connected in parallel” does not necessarily mean the preferred spatially parallel arrangement of the flue gas flues per se, but rather generally the flow-related parallel connection of the flue gas flues independently of their spatial arrangement.

This embodiment is particularly suitable for boilers welded from sheet steel, in which a significant proportion of the heat transfer takes place on the walls of the flue gas flues surrounded by the heat exchange medium,

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while a change in the length of the combustion chamber is less desirable because of the flue gas flow reversal in the combustion chamber.

However, in the case of a corresponding boiler design, the partial shutdown of the flue gas flues can also be carried out together with a change in the combustion chamber length.

In the case of boilers with trains connected in series, one or more trains can be short-circuited as required.

According to a further embodiment of the invention, a shut-off device is arranged, preferably at the end or beginning of the respective train, which, e.g. is a slidable cover plate arranged in the axial direction of the train before its start or after its end, or a flap-like, rotatable plate which, like a carburetor throttle valve, releases or blocks the flow in the respective train.

In the simplest case, the adjustment elements that change the heat transfer surface in the boiler are adjusted manually, e.g. when a certain outside temperature is exceeded or when changing the burner output to half load, the appropriate adjustment of the adjustment elements is carried out.

According to a preferred embodiment of the invention, a temperature sensor is arranged between the flue gas outlet of the boiler and the outlet of the chimney, the signal of which is fed to a control device which, by appropriately controlling the motor-adjustable actuating devices for changing the heated inner surface of the boiler, maintains a largely constant flue gas temperature at the flue gas outlet of the boiler settles. The flue gas temperature used as the setpoint can be selectable so that the boiler according to the invention can be adapted to the local chimney conditions by simply preselecting the flue gas temperature.

In this case, the burner output is set manually or automatically using e.g. adjusted to the expected or present heat requirement by the outside temperature-controlled control device, and depending on the burner output, the control device controlled by the smoke gas temperature then initiates the setting of the size of that heated inner surface which is just required to reach the desired smoke gas temperature.

Thus, the boiler according to the invention can always be operated automatically and with optimum efficiency, irrespective of the burner output just present.

The object of the invention is explained in more detail with reference to the accompanying schematic drawings; show it:

Figure 1 shows the longitudinal section through a sectional boiler according to the invention in cast design with an actuating device which is set to full load operation.

Fig. 2 shows the boiler of Figure 1, set to the smallest part-load operation.

3 shows a boiler similar to FIG. 1, with another actuating device set to full load operation;

4 shows the boiler of FIG. 3, set to the smallest part-load operation;

Fig. 5 essential parts of a boiler welded from sheet steel in the oblique view;

6 shows a boiler similar to that of FIG. 5, in longitudinal section, set to full load operation;

Fig. 7 the boiler of Figure 6 in horizontal section.

Fig. 8 is a boiler in longitudinal section similar to that of FIG. 6, with another adjusting device, set on

Full load operation;

Fig. 9, the boiler of Figure 8, in horizontal section.

Fig. 10 is a vertical longitudinal section through a boiler with a hot combustion chamber, and

Fig. 11 is a vertical cross section through the main parts of the latter.

In the drawing, the same reference symbols are used throughout for the same or similar elements.

In Fig. 1 a multi-unit cast boiler 1 is shown, with a combustion chamber 2, which is distributed evenly over its length, e.g. Has upwardly extending flue gas passages 3, which open into a train 3a running parallel to the combustion chamber, to which an exhaust pipe 4 connects, which is connected to a heating chimney.

The front of the boiler 1 is closed by a front end wall member 5, while the back of the boiler is closed by a rear end wall member 6.

On the front end wall 5 there is a burner 7, the main part 8 of which is arranged outside the boiler.

As can be seen from the drawing, the burner 7 has a burner neck 9 arranged axially to the combustion chamber 2, which penetrates the front wall member 5, is displaceably mounted therein and carries a disk 10 made of fireclay or heat-resistant steel at its end lying within the combustion chamber 2.

The burner 7 consisting of the main part 8 and the neck 9 and the disk 10 carried by the neck 9 can be displaced together in the axial direction of the combustion chamber 2 by means of an electrical, pneumatic, hydraulic or mechanical device similar to that shown in FIGS. 5-9.

Fig. 1 shows the position for full load operation of the burner; In this position, the burner 7 is moved out of the combustion chamber 2 until only the end of the neck 9 opens into the combustion chamber 2 and the disc 10 rests on the inside of the front end wall 5.

In this position, the combustion gases sweep the entire combustion chamber 2 and escape through all flue gas passages 3.

This position shown is the burner 7 when the boiler 1 is to be operated at full load in winter, the boiler 1 being constructed and designed such that in this case the combustion gases flowing through the exhaust pipe 4 are the desired ones for the respective chimney barely permissible, have the lowest temperature.

In the illustration according to FIG. 2, the burner 7 has moved so far in the direction of the combustion chamber 2 that it assumes its corresponding end position. In this case, as shown in the drawing, 40% of the combustion chamber and the flue gas passages 3 are shielded by the disk 10 against the flame of the burner 7, which is operated at its lowest power, as is the case in the summer months.

The position of the burner 7 shown is matched to the reduced burner output and the correspondingly lower amount of flue gas so that the flue gases flowing through the exhaust pipe 4 have the same temperature as in full-load operation when all flue gas passages 3 are released as a result of the retracted burner 7.

In the exhaust pipe 4, a temperature sensor 11 is attached to measure the flue gas temperature and is connected via a control device (not shown in the drawing) to the above-mentioned actuator for the axial movement of the burner 7, in order to further increase the flue gas temperature if the flue gas temperature is too high or too low To move the combustion chamber in or out of it.

The burner 7 and with it the disc 10 can also be an intermediate position between the s shown in FIGS. 1 and 2

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Take end positions; this intermediate layer is useful if the boiler is to be operated in autumn or spring, i.e. in a transitional period.

3 and 4 also show a cast sectional boiler similar to that shown in FIG. 1. It has the following differences from the latter:

the burner 7 has a normal connection piece 9 and is fixed in place on the front end wall 5,

- The disc 10 is omitted, and

- On the rear end wall 6 in the axial direction of the combustion chamber 2 by means of a drive 13 a baffle wall 12 is arranged, which essentially fills the clear cross section of the combustion chamber 2.

In full-load operation (FIG. 3), this baffle 12 is retracted to the rear end wall 6, while in the position according to FIG. 4 it has moved so far into the interior of the combustion chamber 2 that it accounts for 40% of the combustion chamber and the Turns off flue gas passages 3 by directing the flame emanating from the burner 7, which strikes them, as shown in FIG. 4, into the remaining flue gas passages 3 and from there into the exhaust pipe 4.

In this embodiment too, the baffle 12, like the disk 10 in the embodiment of FIGS. 1 and 2, can assume different positions in accordance with the respective burner output.

The embodiment according to FIGS. 1 and 2 is preferred over that according to FIGS. 2 and 3, since in the former the rear wall of the boiler is also available as a heating surface.

While a cast boiler was shown in FIGS. 1 to 4, in which the flue gas passages 3 are distributed over the entire length of the combustion chamber 2, FIG. 5 shows a steel boiler which is embodied in a welded construction and has a closed combustion chamber 2; the flame of the burner 7 burns out in this combustion chamber 2. The flue gas is deflected and returned on its rear wall, and then flows upward to the inlets of flue gas flues 14 arranged parallel to one another, which are arranged above and parallel to the combustion chamber 2 and, like the combustion chamber, are surrounded by the heat exchange medium.

In such a boiler, the invention is advantageously implemented in that part of the trains 14 are essentially blocked for the flue gas.

For this purpose, two slides 15 are arranged opposite the inlets of two of the four flue gas flues 14, which can be moved up to the flue gas flues 14 by means of an actuator 13 in order to close them.

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In the position shown in FIG. 5, the slides 15 are so far away from the ends of the associated flue gas flues 14 that the flue gas flow is not impaired by the slides 15.

As can be seen in FIG. 5, the actuator 13 has a shaft which carries a control cam for each of the slides 15 held in contact with the associated control cam by a spring (not shown). Both slides 15 are thus controlled jointly by an actuator, although the cams 17 can be shaped differently, so that the two slides 15 can then assume a different position.

It is thus possible to shut off either or none of the two flue gas flues 14 opposite the slides 15 and thus to compensate for three different burner load conditions, such as may be present in summer, spring or autumn and winter operation .

For better clarification, the burner of FIG. 5 is shown in elevation in FIG. 6 and in plan in FIG. 7, the operating position being shown in each case in which all flue gas flues 14 are open.

Also in the embodiment of FIGS. 6 and 7, a temperature sensor 11 can be arranged in the exhaust pipe 4, which controls the actuator 13 via a control system in such a way that the most suitable number of flue gas flues 14 is opened or blocked.

FIGS. 8 and 9 show an embodiment similar to FIGS. 5 to 7, but with the difference that the actuator 13 with the slides 15 is arranged at the chimney end of the flue gas flues 14. The advantage of this arrangement is, in particular, that the entire outer surface of the front end wall 5 is available for the burner 7.

A mechanical or electromechanical actuator 13 is shown in FIGS. 5 and 6 and 7, respectively, while a hydraulic or pneumatic actuator 13 is shown in FIGS. 8 and 9.

The boiler shown in FIGS. 10 and 11 differs from the boiler according to FIGS. 8 and 9 essentially in that it has a hot combustion chamber 2 which is not flushed with water. Within the hot jacket 2a of the same, the flue gases reverse as in the boiler according to FIG. 8 and reach the flue gas outlet 22 through trains 20 which are evenly distributed over the circumference and which are surrounded on the outside by the axially ribbed water jacket 21. The shut-off mechanism for some of the trains is here the same as in the boiler according to FIGS. 8 and 9.

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Claims (14)

663083 PATENT CLAIM E 1. Boiler, in particular for space heating purposes, which is flowed through by a heat transfer medium and heated by means of an oil or gas burner, the output of which can be adjusted according to the heat requirement, characterized in that the size of the interior heated by the flame and / or the flue gas of the burner Boiler surface can be reduced in adaptation to the smaller output of the burner (7) at partial load by blocking part of the flame and / or flue gas path. 2. A boiler according to claim 1, characterized in that the size of the heated boiler surface is reduced by reducing the effective combustion chamber (2). 3. A boiler according to claim 1 or 2, characterized in that the burner (7) has a neck (9) carrying the flame at a distance from the rest of the main burner part (8), and that the amount by which the neck enters the combustion chamber (2) protrudes, is adjustable, the length of the neck (9) is advantageously dimensioned such that it projects so far into the combustion chamber for operation at the lowest power that the end of the neck (9) practically in the middle of the Combustion chamber. 4. Boiler according to claim 3, characterized in that with the adjustment of the burner (7) surrounding the neck (9) near its end facing away from the main burner part (8) and approximately filling the cross section of the combustion chamber (2) ) is adjustable. 5. Boiler according to claim 4, characterized in that the disc (10) is carried by the neck (9). 6. A boiler according to claim 1 or 2, characterized in that a burner (7) carrying end wall (5) of the combustion chamber (2) can be moved into the combustion chamber together with the burner. 7. Boiler according to claim 1 or 2, characterized in that a burner (7) opposite end wall (6) of the combustion chamber (2) is displaceable therein. 8. Boiler according to claim 1 or 2, characterized in that a burner (7) opposite end wall (6) of the combustion chamber (2) is connected upstream of an adjustable baffle (12). 9. Boiler according to one of claims 1 to 8, with a plurality of flue gas flues connected in parallel to the combustion chamber, characterized in that at least one of the flue gas flues (14) and at most all but one can be shut off. 10. Boiler according to one of claims 1 to 9, with at least two flue gas flues connected in series to the combustion chamber, characterized in that at least two flue gas outlets, with two flue gas outlets, one of which is provided at the end of the last flue gas flue and the other at the end of a predicted flue gas flue, and in that for operation with a lower boiler output, the flue gas outlet is opened at the end of the previous flue gas flue and is closed at the end of the last flue gas flue. 11. A boiler according to claim 9 or 10, characterized in that a shut-off device (15) is arranged at the end or at the beginning of the respective flue gas flue (14). 12. A boiler according to claim 11, characterized in that the shut-off device is a plate (15) which can be displaced in the axial direction of the flue gas flue (14). 13. A boiler according to claim 11, characterized in that the shut-off device is a rotatable plate which between a flue gas flue (14) at least largely shut off transverse position and a position in which it Level runs in the longitudinal direction of the flue gas train, is adjustable. 14. Boiler according to one of claims 1 to 13, characterized by a on the flue gas outlet (4) of the boiler (1) attached temperature sensor (11), which is connected via a control device with one or more actuating devices (13) for changing the heated, inner boiler surface is.