FI77526B - CENTRALVAERMEPANNA. - Google Patents

Description

77526

Central heating boiler - Centralvärmepanna

The invention relates to a central heating boiler comprising a firebox with a heat generator such as an oil or gas burner, a water space surrounding the firebox which is part of the heating water circuit and bounded by the boiler walls, and flue gas ducts passing through the firebox and flue gas outlet, in addition, the boiler is equipped with a domestic hot water heat exchanger.

A heating system with such a boiler has one of the most significant problems with the high slowness of the system. The slowness of the boiler is particularly disturbing in the heating of hot water. For example, in summer, when the need for heating is low and the boiler water is correspondingly cooled, the entire amount of boiler water has to be heated and waited for it to warm up before a shower can be taken with warm water. Thus, electrically heated backup systems are often used to produce domestic hot water during the warm seasons. This, of course, increases the overall cost.

In order to increase the internal circulation of boiler water, it is known (FI patent publication 24680) to arrange water circulation pipes passing through the furnace. However, the passage of these water recirculation pipes through the walls of the furnace is structurally difficult to implement, and in burner operation such pipes interfere with the burner flame and thus cause additional sooting.

In another known solution (FI patent publication 32805), the water circulation pipes are axial pipes in the annular casing surrounding the furnace and the flue gas duct forms a ring space surrounding the annular casing. This arrangement is also structurally difficult to implement and is suitable for small, cylindrical boilers.

FI patent application 2942/68 discloses a heating boiler, 2 77526 with a heat exchanger placed inside a furnace. However, this heat exchanger is primarily connected to the heating water circuit and thus does not serve the rapid heating of the domestic hot water.

The object of the invention is to provide a central heating boiler with a hot-water hot water exchanger, which, in addition to the above-mentioned features, has the essential advantage that primary and very fast heating of hot water can be ensured in all operating conditions.

This object is achieved by the invention on the basis of the features set out in the appended claims.

In the central heating boiler according to the invention, the tip part of the burner flame directly and immediately heats the water in the water space of the domestic hot water heat exchanger. In this case, hot hot water is obtained as soon as the burner is started, even if the burner has been at a standstill for a long time and the boiler water has cooled down. Also during the heating season, the supply of hot water is ensured with power corresponding to its consumption peaks. As is known, the power requirement for domestic hot water heating is very different in nature compared to water heating in a heating circuit. Significantly higher inertia can be allowed in the heating circuit due to the heat storage capacity of the structures. Instead, the hot water temperature should remain at a certain setpoint while the water consumption varies at a high rate of variation from zero to some maximum value. The invention therefore starts from the premise that the heating of the domestic hot water and the heating of the heating circuit are carried out on a principle which corresponds to said different types of power demand.

In the following, an embodiment of the invention will be described in more detail with reference to the accompanying drawings, in which Figure 1 shows a central heating boiler according to the invention in a schematic vertical section seen from the front.

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Fig. 1A is a sectional view taken along line A-A of Fig. 1, and Fig. 1B shows an alternative embodiment of a detail of Fig. 1.

Fig. 2 shows the boiler according to Fig. 1 in a schematic vertical section seen from the side #, in which Fig. 2 further shows some elements (10, 11 ') which have been omitted from Fig. 1 for the sake of clarity.

Fig. 2A shows a section taken along the line A-A in Fig. 2.

The structure of the boiler is as follows. The thermally insulated plate walls 1 of the boiler delimit a water space 2, inside which there is a lying cylindrical firebox 3, in the opening at the other end of which an oil burner 17 is mounted. The flue gases are led to a flue gas duct 4 connected to an opening at the opposite end of the firebox 3, which is connected by a series of small, vertical, parallel flue gas pipes 5 to an upper collector duct 6, the rear end 6a of which forms a flue gas outlet.

The circulating water supplied to the heating coils is taken from the top of the boiler to the water space 2 by an opening pipe 7. The lower end of the return pipe 8 of the heating circuit opens in the vicinity of the bottom of the boiler water space. The mixing valve 9 regulates the heating circuit either manually or with an automation jet based on temperature measurement so that it takes place partially or completely through the boiler water space 2 or so that the circulation completely bypasses the boiler when the desired room temperature is reached.

Mounted on the side of the vertical flue gas pipes 5 are split pipes 11 which, together with the outer surface of the flue gas pipes * 5, delimit water recirculation ducts 77526 via which extend for most of the height of the boiler water space. The split pipes 11 can extend below the flue gas pipes 5 as intact pipes close to the bottom of the boiler water space 2. The vertical part of the flue gas duct 4 is also provided with water recirculation pipes 111, which at the duct 4 are formed as split pipes' as shown in Fig. 2a. Above the channel 4, the water recirculation pipes 11 'can extend as intact pipes to the desired height and their upper ends 11b can be placed e.g. in the vicinity of the end of the flow pipe 7.

To heat the hot water, cold water is introduced from a pipe 12, the lower end of which is connected by two pipes through the wall of the firebox 3 to a heat exchanger 13 placed inside the firebox 3, formed by a flat, thick-walled tank placed in the rear wall near the rear wall. In this case, the flue gases have to circulate around the heat exchanger tank 13 while the tip of the burner flame sweeps the front wall of the tank 13. Immediately above the heat exchanger tank 13 is a second tank 14 in flow communication with it, from which hot water is supplied via a pipe 15. The purpose of the tank 14 is to reserve a sufficient amount of water in connection with the tank 13 to prevent overheating and to equalize the heat.

In addition, a conventional coil heat exchanger 10 can be used (Fig. 2}, in which case the valve 16 can be used to select common or separate operation of the heat exchangers 10 and 13. The valve 16 can be a hot water temperature controlled control valve. temperature fluctuations.

In addition to or instead of the water recirculation pipes 11 and 11 'arranged in connection with the flue gas ducts 4 and 5, water recirculation can also be arranged as shown in Fig. 1B so that a second partial cylindrical jacket surface 11' is supported at a distance from the jacket surface. 11 '' 'leading to the top of the boiler. Also in this case, the internal flow of the boiler is obtained as indicated by the arrows. However, in order to minimize the flue gas losses, the solution shown in Fig. 1 is the best possible, in which case a circulating flow is provided which effectively flushes the outer surfaces of the flue gas ducts 5 and 6 just before the flue gases leave the boiler. Thus, heat transfer in the coldest end of the flue gas ducts is enhanced. In a test run performed with a boiler according to the invention, it has surprisingly been found that the so-called the temperature of the flue gases leaving during the idling test or at low load does not reach the boiler-water temperature during the burner operating cycle. It was also found in the test run that when the burner was started after the standstill period, the temperature of the boiler water was gradually raised while the hot water was reduced by an amount corresponding to the peak consumption.

The operation of the boiler is as follows. When the stopped and cold heating system is started, the valve 9 is in a position where the flow of the heating circuit takes place completely through the water space 2 of the boiler through the pipes 7 and 8. When the burner 17 is started, the flame immediately heats the heat exchanger tank 13, whereby hot hot water is immediately available. The small delay caused by the tank 14 is insignificant compared to a conventional domestic hot water system heated by boiler water via a heating coil. The flue gas ducts 4, 5 and 6 start to heat, whereby water hotter than the surrounding boiler water begins to discharge from the upper ends 11b of the flow pipes 11, 11 'and / or 11' ". By placing the upper ends 11b below the flue gas duct 6 The heated water rises to the top of the boiler, from where it is immediately available to the flow pipe 7. From the lower end of the pipe 8, the cooled water in the heating circuit flows to the bottom of the boiler, from where it flows to the lower ends 11a. that in the initial stage of heating the temperature of the radiators may be substantially higher than the temperature of the water in the water space 2, except for the water which discharges from the upper ends 11b of the recirculation pipes to the upper part of the boiler.

When, for example, controlled by a room thermostat, the valve 9 begins to close, an increasing part of the hot water discharged from the pipes 11, 11 'and / or 11' '' is directed back towards the lower part of the water space, creating a circulating flow mixing the entire boiler water space. The upward flow takes place through recirculation channels arranged in connection with the hot surfaces and the downward flow takes place through the free water space 2.

When the boiler thermostat placed in the water space 2 at a suitable location detects that the water in the water space 2 has also reached the preset temperature, the burner 17 stops. During the burner standstill, the heat stored in the boiler water can be utilized in both the heating circuit The boiler water temperature range can be considered lower than usual, as no significant system delay occurs when the heating demand resumes. In this case, the total heat loss also decreases.

The invention thus enhances the heat transfer in connection with the furnace itself and also in connection with the flue gas ducts before the flue gases escape. It is advantageous to use a larger number of small-diameter flue gas pipes 5, whereby due to the small diameter of the pipes 5, their heat transfer efficiency by means of convection is as good as possible. When the outer surfaces of these pipes are flushed with recirculated water taken from the bottom of the boiler, the flue gases are removed at a temperature substantially corresponding to the temperature of the boiler water. This means reducing the flue gas losses to their theoretical minimum value with a relatively simple structure.

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In Fig. 1, reference numeral 18 denotes a water pipe terminating in a nozzle, which can be used, for example with push-button control, to perform water flushing of the flue gas ducts 5.

In the foregoing description, and also in the claims below, the heating circulating medium is referred to as "water" for simplicity, as it is the most common heating circulating medium. However, it is clear that the invention can be carried out using any liquid heating circulating medium which can be selected, for example, with a view to preventing freezing.

Claims (2)

77526 A central heating boiler comprising a furnace (3) to which a heat generator such as an oil or gas burner is connected, a water space (2) surrounding the furnace forming part of the heating water circuit bounded by the boiler walls (1) and through the water space (2) flue gas ducts (4, 5, 6) pass between the firebox (3) and the flue gas outlet (6a), in addition to which the boiler is equipped with a hot water heat exchanger, characterized in that the heat exchanger includes a heat exchanger tank inside the firebox (3) 13) in a plane parallel to the rear wall of the furnace at a small distance from the rear wall having a flue gas outlet to which the flue gas duct (4) is associated and said heat exchanger tank (13) communicates with the tank (14) outside and above the furnace (3) ), the volume of which is several times the volume of the heat exchanger tank (13). Boiler according to Claim 1, characterized in that in addition to the domestic hot water heat exchanger tank (13), a conventional coil heat exchanger (10) is arranged in the boiler water space (2), the valve (16) being used to select common or separate operation of the heat exchangers (10, 13). .