DE2648855A1 - Heat loss reduction unit for oil-fired boilers - uses absorption refrigerator with condenser and generator in flue gas flow - Google Patents

Abstract

The unit is for the reduction of heat loss, caused by flue gas, in oil- or gas fired boilers. It uses a conventional absorption refrigerator (3). The condenser (4) and the generator (6) of the refrigerator are located in the flue gas flow (2), with the generator next to the boiler (1) and the condenser at a distance downstream from it. The pipe (14) for the water supply to the boiler passes through the absorber and the condenser. Part of the pipe is formed by a heat exchanger. The refrigerator has an associated heat exchanger, with one end connected to the refrigeration medium conduit (13), and with the other end connected to the absorber (5).

Description

Mr. Dipl.-Ing, Donald Herbst Marienplatz 11, 100O Berlin 45

Device for reducing the heat losses caused by flue gases in the case of an oil or gas boiler

The invention relates to a device for reducing the heat losses caused by flue gas in an oil-filled system or gas-fired boilers,

In such boilers, the water and hydrogen contained in the fuel in the flue gas produce water vapor f which, when cooled below the dew point, condenses back to water and precipitates out of the flue gas. In the case of heating oils containing sulfur, the dew point is approx. 150 ° C, and the boiler and burner are designed and operated in such a way that the flue gas temperature does not fall below the dew point temperature in any part of the system, including the chimney.

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As a rule, therefore, the smoke gases have at the boiler outlet a temperature of 210 to 270 ° C.

When the boiler is operated in this way, the flue gases result in losses of various types, which overall a share of 20 to 30% compared to a system whose flue gas is released into the open at 20 C. The losses caused by the high temperature of the flue gases are made up of the so-called exhaust gas loss, which is due to the high heat content of the exhaust gases, from the loss due to unburned CO; this loss could be Avoid by making appropriately large quantities available of combustion air. However, since this would increase the exhaust gas losses significantly, there is a loss in CO in the amount of 0.5 to 1.5% in the flue gas accepted. Finally, the so-called water vapor loss occurs, which is caused by the use of the condensation heat of the Water vapor is given.

To such high losses, which are to a considerable extent detrimental to the economic operation of the boiler affect, reduce, you have a known heat exchanger in the flue gas flow behind the boiler outlet, for example in the form of a finned tube battery, arranged from the coming from the heating system, through the heating

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heating water to be heated is flowing through the boiler again. By using such a heat exchanger, the temperature of the flue gases is reduced to a certain extent. Assuming that the temperature of the heating water flowing back into the boiler is 60 ° when entering the heat exchanger, the flue gas can be reduced to 70 ° C, whereby so much condensed water precipitates on the heat exchanger until the flue gas corresponds to one of its cooling: has reached the dew point of 70 ° C. For this purpose, the heat exchanger is made of corrosion-resistant material; the condensation water from the flue gases on the heat exchanger is collected, neutralized and drained off after it has cooled down accordingly. But since the ^{flue gas cooled to 70 °} C. in the heat exchanger is further cooled down to the exit of the chimney after leaving the heat exchanger, condensation water would occur in the system, which should be avoided. For this reason, the flue gases cannot actually be cooled down to 70 ^° C. by the heat exchanger, but the flue gas temperature must be so much higher at the exit of the heat exchanger that a loss of condensed water in the system up to the exit of the chimney is definitely avoided will. The flue gases can therefore not be cooled to 70 C with the heat exchanger, but may only be cooled to the extent that the

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Temperature of the flue gases leaving the heat exchanger soweijt is above the dew point of 150 ° C, that a failure of condensation water is avoided. Through the heat exchanger are thus caused by the flue gas temperature Losses are only reduced to a limited extent, but not completely avoided, which will only be achieved when the Flue gases can be cooled down to the ambient temperature while heating the heating water at the same time.

The applicant has set himself the task of establishing a facility to create j which makes it possible to adjust the flue gas temperature in the heating system down to the ambient temperature of approx. 20 ° C and the heat released by this reduction to be used to the full extent for reheating the heating water, and thus to achieve an optimal use of energy.

This object is achieved according to the invention in that an absorption refrigeration machine known per se is used is, their evaporator and their expeller in such a way in the flue gas flow are arranged that the expeller is adjacent to the boiler and the evaporator at a distance from this downstream and that the line for the heating water to be supplied to the boiler through the absorber and the condenser is led

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An absorption refrigeration machine is known per se; it is used to raise heat from a low temperature level to pump a higher level in a refrigeration cycle using a liquid as a transport medium for the refrigerant. The mode of action is as follows. In an evaporator, the goods to be cooled are kept at a low temperature level is withdrawn by the refrigerant. The refrigerant that evaporates here flows into a sorber where the Refrigerant vapor is absorbed by the cold solvent. The absorber is enriched with the refrigerant Solution conveyed by a pump into an expeller, By supplying heat to the expeller, the refrigerant is expelled, which in a subsequent condenser is liquefied at a high temperature level. This results in a poor solution that has been freed from the refrigerant and becomes the absorber flows back. The two streams of poor and rich solution are passed through a heat exchanger so that the cold rich solution is preheated by the warm poor solution and the latter is cooled at the same time. The solvent pump is the only moving part of the refrigeration cycle .

The applicant has recognized that when assigning the known absorption refrigeration machine in the claim characterized!

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Way to the flue gas flow of a boiler Cooling of the flue gases can reach the ambient temperature, with the heat released by the cooling in fully released to the heating water to be heated again will. Because the hot flue gases at the boiler outlet can be used as heating means for the expeller, where a significant heat release results in a significant temperature decrease leads ,, and in that the smoke gases then through the Evaporator are performed, i.e. that as a heating means for the Refrigerator the same flue gas is used, which is then cooled in the evaporator, the temperature of the flue gas in the evaporator by extracting heat for the purpose of evaporating the refrigerant to under Cooled 20 ° C. All of the heat released by the cooling of the flue gas is transferred to the heating water, which is passed through the absorber and to the condenser where it is passed it is preheated to the extent that only reheating is required in the boiler to bring it to the required temperature bring to.

The heating water can either be fed through the absorber or the condenser first, or it can also be fed into parallel currents are divided, one current being passed through the absorber and the other being passed through the condenser

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The advantage of using the absorption refrigeration machine according to the invention is that exhaust gas losses can no longer occur at all, since the flue gases are cooled down ^{to the ambient temperature in the vicinity of 20 ° C.} Losses due to unburned CO can also be avoided, since the combustion air can be increased to such an extent that complete combustion is achieved without an increase in exhaust gas losses. Due to the cooling of the flue gases down to the ambient temperature, almost all of the water vapor condenses and the evaporation; = heat is fed into the heating water via the absorption machine. The heat losses caused by the flue gases can therefore be avoided almost completely. In fact, the efficiency of the furnace is increased by the absorption chiller from 70 to 80% to almost 100%. On the other hand, there is only a slight additional energy consumption for the solvent pump and the higher fan power for the transport of the increased combustion air for the complete combustion of the CO. These losses can at most be rated at 2 to 3%, so that an extremely high energy saving is still achieved by using the absorption refrigeration machine.

Another important advantage is that the absorption refrigeration machine has not yet been able to avoid it

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Environmental pollution by pollutants is practically completely avoided, as there is no harmful CO gas in the environment is emitted and the sulfur content of the exhaust gases is largely due to the water condensed in the system the smoke is extracted. The sulfur contained in the condensed water can be easily removed are neutralized, whereupon the water treated in this way can be fed to suitable further use.

Another feature is that between the evaporator and the expeller is located in the flue gas flow Heat exchanger is arranged, which forms part of the heating line. By switching on according to the invention a heat exchanger through which the heating water flows in the absorption refrigeration machine is achieved that the latter can be kept correspondingly smaller in their design.

Another feature of the invention is that the absorption refrigeration machine is one of the by the boiler in the heating room radiated heat is assigned to the heat exchanger with its one end to the from the condenser to the evaporator leading refrigerant line is connected and at its other end to the

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Absorber is connected. Due to the radiation from the boiler Losses occur in the room air in the boiler room, which can amount to between 6 and 12% of the boiler output. By the invention Arrangement of the additional heat exchanger acted upon by the heat radiated into the boiler room If the absorption refrigeration machine is used, these losses can also be avoided by removing the heat from the room air is fed to the heating water via the refrigerant.

By connecting further additional heat exchangers to the absorption refrigeration machine, other heat sources can be used can also be used to heat the heating water. For example, an available water Heat can be extracted, which is fed to the heating water, and cooled in this way by the heat exchanger For example, water can be used to cool air in air conditioners.

If larger other heat sources are present, it can be achieved according to the invention that the boiler output is exclusively to heat the expeller of the absorption refrigeration machine is used, so that the heating water only through the absorption Chiller is indirectly heated.

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In a further embodiment of the invention, the absorption refrigeration machine also be connected as a resorption system. If there are larger temperature differences between the flue gases as refrigerated goods and the heating water as a coolant have to be overcome, the switching of the absorption refrigeration machine is often used more economical as a resorption plant. The absorption system has an additional one compared to the absorption refrigeration machine Solvent circuit, and the condenser is replaced by a resorber and the evaporator by a degasser. An external refrigerant circuit runs between the resorber and the degasser. The cold vapor expelled in the expeller is absorbed in the resorber and in the degasser expelled from the refrigerated goods at a lower pressure by heat extraction and passed on to the absorber. The resorption system is arranged in such a way that its degasser and expeller are arranged in the flue gas flow that the expeller is adjacent to the boiler and the degasser at a distance downstream of this, and the line for the heating water to be supplied to the boiler is through the absorber and led the resorber.

The accompanying drawings show embodiments of the Invention, and it means »

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Fig, 1 schematic representation of the assignment

the absorption chiller to the flue gas flow of the boiler, whereby the refrigerant and solvent circuit of the absorption refrigeration machine is shown;

FIG. 2 shows the representation according to FIG. 1 without refrigerant; and solvent cycle, the The running of the heating water is shown; and

FIG. 3 shows a representation according to FIG. 1 with one of the absorption refrigerating machine assigned, the use of the heat exchangers used to heat the room,

FIG. 1 shows the boiler heated with oil or gas 1, from which the flue gases are discharged into the open air through the flue gas pipe 2 via a chimney, not shown. The cold absorption machine 3 has, in the usual way, an evaporator 4, an absorber 5, and an expeller 6 and a condenser 7. The expeller 6 is located behind the boiler 1 in the flue gas tube 2 and the evaporator 4 is also arranged at a distance behind the expeller 6 in the flue gas pipe 2, so that the ι released from the boiler 1

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Flue gases first pass the expeller 6 and then the evaporator 4, the flue gases being extracted by heat be cooled in the expeller 6 and in the evaporator 4. When the smoke gases coming from the expeller 6 the Pass evaporator 4, the refrigerant contained in this .m is evaporated by the flue gases, the flue gases be cooled to a temperature below 20 ° C. The evaporated refrigerant comes out of the evaporator 4 in the absorber 5, where it is absorbed with the release of heat by the solvent contained in the absorber 5, DAs Solvents enriched with the absorbed refrigerant is by a pump 8 via the line IO shown in solid lines via a heat exchanger 9 dem Expeller 6 supplied. In the expeller heated by the flue gases leaving the boiler 1, the Refrigerant expelled from the solution in vapor form, the flue gases being cooled by extracting heat. The expelled Refrigerant enters the condenser, where it is liquefied at a high temperature. That of that Refrigerant freed solvent is indicated by the dashed line Line 11 shown in lines fed back to the absorber 5 as a warm solution via the heat exchanger 9

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The liquefied refrigerant is discharged from the condenser 7 via the line 12 provided with a throttle valve 13 returned to the evaporator 4, from where it passes through the absorber 5, the expeller 6 and the capacitor 7 experiences a new cycle. In the heat exchanger 9 of the absorption refrigeration machine the cold rich solution in line 10 is caused by the heat poor solution is preheated in line 11, at the same time the warm cold solution is cooled accordingly.

FIG. 2 shows the heating water line 14 passed through the cold absorption machine 1. The cold heating water coming from the heating system, ^{cooled to approx. 60 °} C., is passed through the absorber 5, where it is heated by the heat extracted from the flue gases in the evaporator 4 . The heating water then passes through a heat exchanger 15 arranged in the flue gas pipe 2, which is arranged between the expeller and the evaporator. In the heat exchanger 15, with simultaneous cooling of the flue gases, the heating water is further heated. The heating water is then passed through the condenser 7, where it is further heated by the high temperature level prevailing in it, in order to finally be fed through the boiler 1 for final heating and from there back into the heating system. All of the heat released in the absorption chiller is transferred to the heating water in this way, with the flue gases after passing through the

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Evaporator 4 so that they can be discharged to the outside without occurrence of heat loss through the chimney _f to a temperature of about 20 ⁰ C are cooled. The absorption: the refrigeration machine can also be operated without the interposition of the heat exchanger 15. The arrangement of this heat exchanger 15 has the advantage that the absorption refrigeration machine 3 can be designed to be smaller.

FIG. 3 shows a modified embodiment according to Figures 1 and 2, in which, in addition, the heat radiated into the room by the boiler 1 for heating the heating water is exploited. For this purpose, a further heat exchanger 18 is arranged in the space accommodating the boiler 1, which is acted upon by the fan 19 with the heated room air will. On which the liquefied refrigerant from the condenser 7 into the evaporator 4 is line 13 a branch 16 is connected, which leads into the heat exchanger 18. The other end of the heat exchanger 16 is via a Connection 17 connected to the absorber 5. Part of the liquefied refrigerant is via line 13 in the Evaporator 4 passed, while another part of the refrigerant via branch 16 through the heat exchanger 18 is fed to the absorber 5 via the nozzle 17.

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The heat exchanger 18 heated by the room air results in evaporation of the heat exchanger 18 passing through Refrigerant, so that the heated room air proportionally used to heat the heating water in line 14 will.

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Claims (2)

EXPECTATIONS 1,) Device for reducing the heat losses caused by flue gases - ^ heat losses in a boiler operated with oil or gas, characterized in that a known absorption refrigeration machine (3) is used, its evaporator (4) and its expeller (6 ) are arranged in the flue gas flow (2) in such a way that the expeller (6) is adjacent to the boiler (1) and the evaporator (4) is at a distance from it downstream, and that the line (14) for the boiler (1) to be supplied Heating water is passed through the absorber (5) and the condenser (6) of the absorption refrigeration machine (3) 2. Device according to CLAIM 1, CHARACTERIZED BY, that between the evaporator (4) and the expeller (6) a heat exchanger (15) located in the flue gas stream (2) is arranged, which forms part of the heating water line (14), 3, device according to claim 1 and 2, characterized in that that the absorption refrigeration machine (3) is one of the radiated by the boiler (1) in the boiler room - 17 - 809817/0557 ORIGINAL IMSPtCTEO -Vf- Heat-acted heat exchanger (1) is assigned, the one end to the refrigerant line (13) leading from the condenser (7) to the evaporator (4) is connected and its other end is connected to the absorber (5), 4, device according to claim 1 to 3, characterized in that in a further one of the absorption refrigeration machine associated heat exchanger according to claim 3 is used as a heat source available water, which is used after cooling in the heat exchanger in air conditioning units to cool air. 5, device according to claim 1 to 4, characterized in that in the presence of larger heat sources, these over additional heat exchanger according to claim 3 are connected to the absorption refrigeration machine and that the Boiler output is used exclusively to heat the expeller of the absorption refrigeration machine and that The heating water is indirectly heated exclusively by the absorption refrigeration machine, 6, device according to claim 1 to 5, characterized that the absorption refrigeration machine is connected as a resorption system, the condenser being - 18 - 809817/0557 About and the evaporator is replaced by a degasser, and the expeller assigned to the resorber adjacent to the boiler and the degasser is arranged at a distance therefrom downstream, and the Line for the heating water to be supplied to the boiler is passed through the absorber and resorber. 8098 17/0557