JPH0364790B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to an absorption type water heater that uses a water-lithium bromide solution as a heat medium and uses an absorption type heat pump cycle.

In conventional water heaters of this type, the hot water is directly heated by the combustion gas from the combustor, and therefore the temperature of the combustion exhaust gas cannot be made lower than the temperature of the hot water. Therefore, if we reduce the temperature difference in heat exchange, the water heater will become very large, and from the perspective of preventing acid dew point corrosion, the lower limit of the combustion exhaust gas temperature is around 200℃.
Since boiler efficiency is set at around 80% by high-level standards, there was a risk that energy efficiency would decline.

If the combustion air is preheated using combustion exhaust gas as a countermeasure, the boiler efficiency will increase by only a few percent at most, but the disadvantage is that the gas-gas heat exchanger used will become significantly larger.

In addition, related to this type of water chiller/heater, for example, "Refrigerating" published by the Japan Refrigeration Association (Volume 51)
No. 88, October 1976 issue).

In view of the above, the present invention provides that almost half of the heat discarded in conventional water heaters is water vapor latent heat in the combustion exhaust gas, and when the temperature of this combustion exhaust gas is lowered to room temperature, the remarkable Focusing on the fact that most of the refrigerant can be recovered, the aim is to improve the energy saving effect, downsize the refrigerant heater, and reduce corrosion.

In order to achieve the above object, the present invention uses the heat of combustion exhaust gas generated from a combustor attached to a generator as a low-temperature heat source to be pumped up, and uses this low-temperature heat source to evaporate water refrigerant under low steam pressure. Even in
By using a refrigerant heater and a flash evaporator together, the vapor flow pressure loss is sufficiently reduced.

Embodiments of the present invention will be described below with reference to the drawings.
Among the reference numerals shown in FIG. 1 and FIG. 2, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, 1 is a generator comprising a combustor 1A consisting of a combustion chamber 1Aa, a combustion supply pipe 1Ab, and a combustion air supply fan 1Ac, and an evaporation pipe 1B; 2 is attached to the exhaust gas discharge side of the combustor 1A; A refrigerant heater that uses the combustion exhaust gas as a heat source, 2a is an evaporation pipe installed in the refrigerant heater 2, and 3 is a pipe 10
This is a condenser that communicates with the top of the generator 1 via a condenser and through which a heat medium such as hot water 3a is passed.

Reference numerals 4 and 5 designate a flash evaporator and an absorber installed oppositely in the shell 6. One of the evaporators 4 has a built-in tray or packing 4a, and is connected to the refrigerant heater 2 via a pipe 10 and a pipe 11. The other absorber 5 is connected to the intermediate portion of the generator 1 via a pipe 9, and a heat medium such as hot water 5a is passed therethrough. 7 is piping 1
A solution pump 8 communicates with the generator 1 and the absorber 5 via pipes 15 and 14, respectively, and a refrigerant pump 8 communicates with the refrigerant heater 2 and the flash evaporator 4 via pipes 15 and 16.

Next, the operation of this embodiment configured as described above will be explained.

The combustion gas generated in combustor 1A is transferred to combustion chamber 1Aa.
and the water in the generator 1 through the wall of the evaporation tube 1B.
To heat the lithium bromide solution (hereinafter referred to as solution), refrigerant vapor, or water vapor, is generated. This water vapor flows into the condenser 3 via the pipe 10, gives heat to the hot water 3a flowing through the condenser 3, and is condensed and liquefied.

On the other hand, the liquid refrigerant accumulated at the bottom of the flash evaporator 4 is pumped through the pipes 16 and 15 by the refrigerant pump 8.
The refrigerant flows into the refrigerant heater 2 through the evaporator tube 2a, and is heated by the combustion exhaust gas from the generator 1 to increase its temperature. The liquid refrigerant whose temperature has increased and the liquid refrigerant in the condenser 3 flow through the pipes 12 and 11, join together, and flow into the flash evaporator 4. is taken away and some of it evaporates.

On the other hand, a concentrated solution (hereinafter referred to as a concentrated solution) generated by generating refrigerant vapor in the generator 1 is introduced into the absorber 5 via a pipe 9, and a portion of the sensible heat of this concentrated solution is due to self-evaporation. A portion of each is cooled by hot water 5a. As a result, the temperature of the concentrated solution decreases and it has an absorption capacity, absorbs the refrigerant vapor generated in the flash evaporator 4 and the refrigerant vapor self-evaporated from the concentrated solution, and releases the absorbed heat to the hot water 5a. The absorbed solution (hereinafter referred to as a dilute solution) is sent to the generator 1 again via the pipes 14 and 13 by the pump 12, and the liquid refrigerant is cooled by the heat of evaporation of the refrigerant itself in the flash evaporator 4. The refrigerant is again supplied to the refrigerant heater 2 by the pump 8 via the pipes 16 and 15.

Next, an experimental example will be explained in detail.

The concentration of the dilute solution that has been absorbed in absorber 5 is 63
%, and the temperature is 62℃, the saturation pressure of the dilute solution is approximately
This is 12.7mmHg, and the saturation temperature of the refrigerant in equilibrium with this pressure is approximately 15°C. If the temperature rise of the liquid refrigerant in the refrigerant heater 2 is about 5°C, the refrigerant heater 2
The temperature of the liquid refrigerant flowing out from the refrigerant heater 2 is approximately 20°C, and if a cross-finch tube heat exchanger, for example, is used as the refrigerant heater 2, it is easy to set the temperature of the exhaust gas flowing out from the refrigerant heater 2 to approximately 25°C. be.

The combustion gas contains a relatively large amount of water vapor, which is the oxidation of hydrogen atoms contained in the fuel.
When the temperature of the combustion exhaust gas reaches about 25° C., about 80% of the water vapor is condensed and liquefied. Under these conditions, it is possible to recover approximately 80% of the difference between almost all of the lower heating value, which corresponds to the sensible heat content of the fuel, and the higher and lower heating values, which correspond to the latent heat content of water vapor. . In other words, the boiler efficiency based on higher calorific value is approximately 97-98%, which is approximately 20% more energy efficient than conventional water heaters.

In this case, the temperature of the solution that absorbs the refrigerant evaporated in the flash evaporator 4 is approximately 62°C as described above, so even if the heat exchange head in the absorber 5 is considered, the temperature of the hot water 5a is approximately 50°C. It is possible to make the temperature higher than ℃. In addition, in the condenser 3, the condensation temperature should be approximately 60°C, the temperature of the generator 1 at this time is approximately 120°C, and the pressure of the generator 1 and condenser 3 is approximately 150 mmHg, which is a large It can be maintained sufficiently lower than atmospheric pressure.

Another embodiment shown in FIG. 2 includes a generator 1 and an absorber 5.
A liquid heat exchanger 17 through which a heat medium such as hot water 17a flows is provided in the middle of the piping 9, and a high temperature concentrated solution generated by generating refrigerant vapor in the generator 1 flows into the liquid heat exchanger 17 through the piping 9. The hot water 17a is configured to flow into the absorber 5 after being heated. In other words, part of the sensible heat of the concentrated solution that was released in the absorber 5 in the embodiment (FIG. 1) is transferred to the liquid heat exchanger 17.
The water is discharged into hot water 17a. Since the other configurations are the same as those of the previous embodiment, the explanation will be omitted.

With this configuration, when operated at almost the same temperature as in the previous embodiment, the concentrated solution fed from the generator 1 will be approximately 120°C, so the liquid heat exchanger 17
The temperature of the hot water 17a passed through the condenser 3 and the absorber 5 can be set higher than that of the hot water 3a and 5a passed through the condenser 3 and the absorber 5.

As explained above, according to the present invention, there are various effects listed below.

(1) Due to the absorption heat pump action, approximately 97 to 98% of the higher calorific value of the fuel used can be used effectively, resulting in a significant energy saving effect.

(2) Most of the heat recovered by the refrigerant heater is recovered by the liquid refrigerant, self-evaporated by the flash evaporator, and absorbed by the absorber installed opposite the evaporation tube, reducing pressure loss due to vapor flow. By reducing the temperature of the liquid refrigerant flowing through the refrigerant heater to a saturation temperature commensurate with the saturation pressure of the solution, it is possible to improve the heat recovery rate and downsize the refrigerant heater. .

(3) By condensing most of the water vapor in the combustion exhaust gas, the acid concentration due to SO ₂ , SO ₃ , NO _x , CO ₂ etc. contained in the exhaust gas dissolved in the condensed water is relatively reduced, and Since the temperature also drops to 20-25°C, corrosion of the refrigerant heater due to acid content in the condensed water can be reduced.

(4) While the interior of a conventional water heater is at atmospheric pressure (1 atm) or higher, the interior of the water heater of the present invention is kept at atmospheric pressure or lower, so safety is great.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are system diagrams showing embodiments of the absorption type water heater of the present invention, respectively. 1... Generator, 1A... Combustor, 2... Refrigerant heater, 3... Condenser, 4... Flash evaporator,
5...Absorber, 17...Heat exchanger.

Claims (1)

[Scope of Claims] 1. An absorption water heater equipped with an absorption heat pump cycle, comprising: a generator with a combustor; a refrigerant heater connected to the generator; a condenser communicating with the generator; An absorption type water heater comprising: a flash evaporator communicating with a refrigerant heater and a condenser; and an absorber installed opposite the flash evaporator and communicating with the generator. 2. A heat exchanger is provided between the generator with a combustor and the absorber, and heat is exchanged between the solution supplied from the generator and the heat medium via this heat exchanger. An absorption type water heater according to claim 1.