DE1930372A1 - Gas-fired water heater - Google Patents

Description

Gas-fired water heater.

The invention relates to the further development of the gas-fired water heater, in which the heat of the heating gases through direct contact with the one to be heated Water is transferred, according to patent application P 17 78 151.0.

The operating conditions of these water heaters are all the more favorable, the lower the water heating temperature.

With heating up to only approx. 300 you get an efficiency of around 95 % based on the heat of combustion of the gas, i.e. based on Ho. This high one There are limits to economic efficiency: the exhaust gas leaves one hundred percent saturated with water the device, which leads to additional heat loss due to evaporation at higher exhaust gas temperatures leads.

Therefore, this contact heat transfer principle has been proposed in the patent application to use the temperature of swimming pool water. The water heater after the patent application is therefore mainly used for swimming pool heating.

In friction wheels that are tempered with such water heaters, there is a need to shower with water that is at considerably higher temperatures. The question has therefore been raised whether with such a continuous heat transfer device service water cannot also be heated to a higher temperature.

This is opposed to the physical law that only up to drop temperatures the heat of combustion is exploited equal to the dew point of the gas combustion products above that only the calorific value Hu to finally at the highest temperatures, when approaching the boiling temperatures, to lead to a usage equal to zero. Because then the water heater becomes a low-pressure boiler that blows off into the open without useful power.

Despite these limits recognizable to the person skilled in the art, the Invention with the object of the water heater according to the patent application for to make higher heating temperatures suitable, but with the principle of utilization the heat of combustion H0 to stay.

The first step in solving this task is knowledge of a difference between the two methods for the Contact heat transfer: 1. Finely distributed air blowing of the heating gas into the water, -2. Atomizing the water in the heating gas flow.

When the heating gas is blown in, the top layer from which the exhaust gas takes place exits, the heating temperature. The exhaust gases can only reach this temperature be cooled down. With water atomization, the water can flow in countercurrent to the Heating gases out and the exhaust gas temperature determined by that of the entering water will.

The lowest possible exhaust gas temperature can be almost the same as the inlet temperature be.

Is related to setting an extremely high degree of efficiency.

on Ho a top mel. specified low exhaust gas temperature, so can the heating-up temperature. higher than the flue gas temperature, max. by the heating-up temperature lie in the device.

Because the exhaust gas temperature is only determined by the water inlet temperature is, it is set in principle independently of the heating temperature in the water heater at inlet temperatures of e.g. 15 ° with appropriate construction rel. high heating temperatures of e.g. 75 - 80 ° can be achieved. But it shows with the fact that in certain zones the heat absorption of the water droplets is so high, that a partial evaporation occurs, which is later due to a recondensation is fixed again. this extends the contact path until the borrowed rel. low exhaust gas temperature. The device must be built larger.

In order to circumvent this disadvantage, it has been proposed to use the contact heat exchange device to connect a second, also gas-fired, downstream heater. This should be in conventional way with closed water flow, i.e. 0 h. with fixed heating surfaces, be built. The usual heating temperatures up to a maximum of 95 ° can be reached in this will.

In such a combination, the water is heated in stages. In the first stage is the heat in contact using So in the second stage Conventionally using Mu transfer.

This is technically not possible in any other way, but it is particularly satisfactory for amateur users Users do not because the fuel costs for both devices for the same useful power differ by around 25%.

The invention is based on the surprising idea that the apparently technical impossibility to meet both opposing requirements, can be overcome by a technical trick: with the reheating must Although you use a conventional water heater, this does not apply to that Heating gases. These can be conventionally exploited and then still meet the conditions be subjected to contact heat transfer.

According to the invention, the water should therefore in a first stage the contact heat transfer principle, then in a conventional after-heater heated, its heating gases first in this, then in a second stage in a contact heat exchanger.

An amazingly simple design is proposed for this: The Exhaust gases from the laach heater should enter the contact space for the device in the first heating stage be initiated.

kiese, in principle, a combination of two separate devices, which, as it were, are only connected on the exhaust side, can be further developed Simplify the invention in that the heat exchanger of the afterheater itself is moved into the contact heat transfer space of the first device. Its burner is to increase the output of the after-heater. The after-heating surface can be thereby rel. Keep it small if the exchanger is still in the flow path strongly cooled heating gases.

The one described in the patent application is particularly suitable for this purpose Execution, which consists of a cylindrical housing, a lower part of which is raised into this Atmospheric burner with a standing combustion chamber that is open at the top and a water shielding and heating gas guide plate located at a distance above this opening and about this centrally standing water atomization nozzle directed near the top consists.

For a water heater constructed in this way, the post-heater can be designed as a spiral Snake formed and in the flow path leading out of the combustion chamber in a radial direction Be placed in the direction of the escaping hot gases. The snake its inlet nozzle is connected to the drain pipe of the water heater, is then only a little The hot gases cooled in the combustion chamber are hit directly.

You can dimension the after-heating surface so that the water actually until it is heated up to approx. 950. As previously referred to as a technical utopia Exhaust gas temperature of 20 - 30 ° is a reality.

Such a water heater with an efficiency of 97% related Ho should not only be used for swimming pool water, but also for service water, i.e. taken from a drinking water supply network and its hygienic properties retained water, can be used.

This again contradicting requirement, on the one hand heat transfer according to the contact principle, on the other hand heating of the separately conducted water, included. still on rel.

high temperatures should be met according to the invention, that the heat from the contact device through one on the one hand from its water, on the other hand removed from the supplied fallow water and the heat exchanger Nachheizschlange is supplied, with the drain connection of the contact device under Interposition of an atomizer rack pump and the additional heat exchanger is short-circuited with the inlet connection of the contact device. The water in the The contact device is kept in circulation, it being warmed up first and then is cooled again in the additional heat meter, the domestic water is in the first stage in the additional heat exchanger, in the second stage in the post-heating exchanger heated up.

In principle, the idea of the invention can also be applied to the water heater Carry out with heating gas injection into the water. Then the posterior snake would go first acted upon by the hot gases, then blown them into the contact water, finally the power from the contact water given to the domestic water and this then in the reheater to the required rel. brought high temperature.

The implementation of the invention on the device with water atomization offers Another advantageous addition while by the specified exhaust gas temperature and thus approximates one due to the optimal heating temperature in the first stage constant heating power must be maintained changes with the additional heating in the second stage the post-heating output, i.e. the ratio of the two heat transfer capacities.

If the ratio of the two heating capacities is to be adjustable, the after-heating surface must be variable. This can be achieved if one proceeds from the embodiment described in the patent application, in which an annular water-collecting cup is formed by the extended flange at the bottom of the combustion chamber and the housing. in which stent up to a certain Abstanayaraswasser.

According to the invention, the level is between a lower and an upper one Brand made adjustable, the post-heating coil built so that the part of the heating surface, which takes up the variable part of the power, a height equal to the height difference who has level marks, a level can be raised in the collecting cup Part of the reheating coil can be moved into the water. There is no heat exchange there instead, because the water in the queue and that in the cup are heated to about the same level are. It is assumed that the submerged part of the snake is in contact with the Water supply, or is connected to the additional heat exchanger.

If the entire reheater should be able to be switched off temporarily, see above the height of the snake is to be measured equal to the height difference of the level markers.

Such a gas-fired water heater according to the invention is different differs from the conventional ones due to its extremely low exhaust gas temperatures Water heaters.

In these there would be an enlargement of the heating surfaces by the ones mentioned To achieve exhaust gas temperatures, economically -not acceptable, on the other hand can with the rel. cheap atomization of the first in innumerable tiny droplets the heat Such low flue gas temperatures are usually not sufficient to draw an outside chimney build are also questionable for a normal chimney because of the danger Condensation from the exhaust gas saturated with water vapor.

Therefore, where the gases do not enter directly from the device Free can be discharged, an exhaust fan can be connected downstream. But this should In addition to the exhaust gas, suck in a measured amount of air. The amount of air should be like this be measured so that the dew point of the exhaust gas-air mixture as a result of the cooling of the Mixture on the way is not reached until it escapes into the open air.

The invention is illustrated below with reference to the schematic representations explained in more detail in Fig. 1 - 2; According to Fig. 1, the water heater consists of a housing 1 with an exhaust pipe 2, a combustion chamber 3, an atmospheric one pushed into it Burner 4 and a water shield and Heizgasleitplatte lying over the upper opening 5 built. The lower flange 6 forms the combustion chamber with the lower part of the housing an annular water collection cup 7.

An upwardly directed atomizer nozzle 8 is installed above the plate 5, to which a water supply line 9 is laid.

The water is drained off via a nozzle lo.

The heating gases rise in the combustion chamber 3 through the plate 5 are diverted to the outside and flow in the housing 1 to the nozzle 2.

The water is finely distributed upwards through the nozzle and falls in a mushroom-shaped veil against the rising heating gases downwards and collects in the cup 7.

When it falls down, it splits into many small droplets Water up the heat from the heating gases. These have up to the height of the exhaust nozzle 2 almost assumed the temperature of one splash of water.

So far it is the one described in the patent application Device.

In addition, around the combustion chamber is at the level of the exiting Heizasstromes a water-bearing snake 11 is laid. The heating gases have through the down The bent edge of the plate also received a deflection downwards.

ser flow path of the heating gases and the height of the snake, or their entire surface, the gbf. in a manner not shown with ribs, hadels or other indirect heating surfaces should be occupied, is dimensioned so that they total.

fully affected by the heating gases, which were poorly cooled in the combustion chamber and brings the water to the desired temperature.

The lower end of the snake 12 is connected to a stand next to the housing Heat exchanger 13 connected, the upper end of the coil with a water outlet line 14th

A water supply line leads into the other space in the heat exchanger 13 15th

A pressure pump 16 is installed directly behind the drain connection lo, by which the water is pressed through the exchanger and fed back to the nozzle 8 by 9 will.

The path of the flowing in the line 15, through the exchanger 13 guided and flowing through the snake 11, finally flowing off in the line 14 Water is completely separated from that in constant circulation through the nozzle 8, which Cup 7, the pump 16, the exchanger 13 of standing water.

The water flowing in in 9 with e.g. 150 increases through immediate Contact with the hot gases generates so much heat that it is heated to approx. 5 °, for example. When flowing through the exchanger 13, it is cooled down again to about 150 and occurs with its previous temperature at the nozzle 8 re-enters the circuit.

The water flowing in with lo - 150 in the water line 15 is in the Exchanger 13 preheated to almost 550, in the downstream line 11 to e.g. 850 reheated.

The exhaust gases leave the device at around 200 in the nozzle 2.

The level in the water cup 7 can be between marks 17 and 18 be enrolled. The lowest turn of the snake 11 is slightly above the lower one Level 17. If the level is set higher than mark 17, then part of the Snake in the water.

The part of the surface of the snake that is in the water is not pressurized by the heating gases, the water in the queue and around it, i.e. in the cup 7 have about the same temperature, there is no heat transfer.

The submerged part is therefore dead for heat absorption.

If you want to temporarily switch off the reheating coil completely, then dimension the overall height of the snake equal to the level difference so that it is whole swaps into the water when the level is set to its highest level.

The level can be set automatically by a temperature sensor in line 14 are controlled. The gas burner can also use this sensor 19 be managed.

In Fig 2. is a larger water heating system with a Water heater shown in Fig.l.

It consists of a water heater with contact heat transfer and Post-heating and with an additional heat exchanger switched on, as shown in Fig. and two standing water reservoirs. The device 20 is with the two memories 21,22 through circulation lines 25 tn which a circulation pump. sits 24, connected. A cold water supply line 25 leads into the lower zone of the storage tank, a hot water line from the upper zone of the storage tank to the taps 26.

On the device 20 sits an exhaust fan 27, its intake port on a line 28 to the exhaust port 29 of the device 3o and one into the ambient air .Mining line 31 branches.

The water is in direct circulation through the reservoirs 21,22 and the device 20 is heated. If the heating temperature is not high, the Water only transferred through the heat exchangers attached in or on the device 20 Contact heat can also be heated with a higher set heating temperature by smoothly increasing the directly acted upon by the heating gases Part of the after heating surface without further contact heat absorption through reheating brought to the desired temperature.

Claims (8)

P a t e n t a n s p r ü c h e. 1. Gas humidified water heater in which the heat from the heating gases passes through direct contact with the water to be heated is transferred, according to patent application characterized in that this is also a gas-fired water heater as Post-heater in which the heat is conventionally transferred via fixed heating surfaces, is downstream and its exhaust gases a Nachkihlung by contact heat transfer are subjected to a partial water flow branched off from this. 2. Water heater according to claim 1, characterized in that in the exhaust gases of the after-heater are introduced into its contact space. 3. Water heater according to claim 1 with a standing above the burner, preferably conical and open at the top, spaced by a heating gas baffle shielded combustion chamber characterized in that the heat exchanger of the after-heater as a water-carrying snake 11 in the flow path of the exiting from the heating chamber Put heating gases and its burner 4 is increased by the power of the after heater. Fig.1. 4. Water heater according to claim 3, characterized in that the Actuation of the afterheater by the heating gases is adjustable. Fig.1. 5. Water heater according to claim 4 with one around the combustion chamber lying water collecting cup characterized in that the level in this cup 7 adjustable between an upper and lower mark, 17, 18 and part of the after heating coil 11 is located within the level setting range. Fig 1. 6. Water heater according to one of the preceding claims characterized in that an additional heat exchanger 13 is attached to or in it, the one hand of from the heated water 10, on the other hand from Fresh water 15 is applied so that the heated, cooled back in the Rauscher 19 Water 9 is fed back to it and the water 12 preheated in the Rauscher is fed to the reheater 11 is fed. Fig.1. 7. Water heater according to claim 6, characterized in that of the heating temperature of the fresh water, the output of the burner 4 and preferably or only the activation of the after-heater 11 can be regulated. Fig.1. 8. Water heater according to one of claims 1 - 7, characterized in that that it is followed by an exhaust fan 27 with two intake ports, of which the one 28 connected to the exhaust port 29, the other 31 into the ambient air leads, and that the resulting dew point due to the amount of air sucked in of the exhaust gas-air mixture below the temperature of the mixture when it enters the price is located. Fig 2.