JPH0355744B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-effect absorption chiller/hot water machine, particularly a multi-effect absorption chiller/hot water machine suitable for recovering heat from the exhaust gas of a boiler installed in a high-temperature regenerator. It is.

As shown in FIG. 1, a conventional water chiller/heater of this type has a cold water pipe 1a, a refrigerant distribution header 9, and a float valve 14.
an evaporator 1 with a built-in cooling water pipe 2a and a concentrated solution distribution header 7, a high-temperature regenerator 3 with a built-in boiler 3a, a low-temperature regenerator 4 with a heating pipe 4a, and a condenser with a cooling water pipe 5a. 5, solution pumps 6 and 8, refrigerant pump 10, and low and high temperature heat exchangers 11 and 12.

When producing cold water (during cooling operation), the cooling/heating switching valve 15
is closed, the refrigerant is sprayed onto the cold water pipe 1a of the evaporator 1 from the spray header 9 and evaporated, and this refrigerant gas is sent to the absorber 2. On the other hand, during hot water production (during heating operation)
Then, the cooling/heating switching valve 15 is opened, and the refrigerant is sent to the absorber 2 and mixed with the solution.

In the above-mentioned hot and cold water machine, it is conceivable to exchange heat with the combustion exhaust gas of the boiler 3a and the dilute solution sent from the absorber 2 to the low- and high-temperature regenerators 4 and 3, and to recover heat from the combustion exhaust gas. A steam-fired absorption refrigerator has already been proposed that is equipped with a heat exchanger that exchanges heat with the steam drain heated by the regenerator. In addition, a proposal has already been submitted in which a heat exchanger is provided in the combustion gas exhaust path of the boiler 3a, and a refrigerant liquid is circulated through the heat exchanger to form an absorption heat pump cycle, thereby recovering heat into hot water.

However, when the combustion exhaust gas of the above-mentioned boilers, especially boilers fueled by kerosene or city gas, is cooled to 50 to 60°C, the moisture in the combustion exhaust gas condenses, and this condensed water contains SOx, NOx, HCl, etc. in the exhaust gas. CO ₂ and other substances are absorbed and it becomes strongly acidic water, which corrodes heat exchangers. As a countermeasure, the temperature of the exhaust gas is increased to 70 to 80.
Measures have been proposed to slow the progress of corrosion in heat exchangers by weakening or neutralizing the acidity by preventing condensation by heating the exhaust gas above 40°C or by cooling the exhaust gas to below about 40°C to condense moisture. ing.

However, the solution temperatures in the low-temperature regenerator 4 and the high-temperature regenerator 3 in the water-lithium bromide absorption type water chiller/heater shown in FIG. 1 are 80-90°C and 140-90°C, respectively.
The temperature of the exhaust gas from boiler 3a is about 150℃.
That's all. Therefore, by providing a heat exchanger in the exhaust gas line of the boiler 3a and exchanging heat between the solution in the low temperature regenerator 4 and the exhaust gas, the exhaust gas temperature can be lowered to about 90°C. That is, when the excess air ratio m is about 1.5 and the fuel is kerosene, the efficiency of the boiler 3a can be improved by about 3% and energy saving can be achieved.

However, when heat is recovered to the low-temperature regenerator 4 as described above, there is usually a head difference in position between the boiler 3a and the low-temperature regenerator 4. For example, if the heat exchanger is in a low position, the solution in the heat exchanger can't boil because of the liquid head. Therefore, since only a low heat transfer coefficient can be obtained, a heat exchanger with a large heat transfer area is required. On the other hand, if the heat exchanger is located at a high position, there will be problems such as empty firing spots will occur, corrosion will rapidly progress from the solution side, and it will be difficult to ensure a head difference returning to the absorber 2.

An object of the present invention is to provide an absorption type cooling/heating machine with high exhaust heat recovery efficiency per unit area of a recovery heat exchanger. It is characterized in that the exchanger and the auxiliary heat exchanger provided in the regenerator or the refrigerant flow path of the regenerator are connected via a refrigerant circulation path.

Embodiments of the present invention will be described below with reference to the drawings.
Among the reference numerals shown in FIGS. 2 to 7, the same reference numerals as those shown in FIG. 1 indicate the same parts.

In FIGS. 2 and 3, 16a, 16b
is a heat exchanger disposed in the exhaust path 17 of the combustion exhaust gas generated by the boiler 3a, and the heat exchanger 16
a is the header 16a ₁ , 16a ₄ and the header 16a ₁
A large number of heat transfer tubes 16a ₂ connected to _a large number of plate fins 16a ₃ orthogonal to these heat transfer tubes 16a 2
It is made up of. The other heat exchanger 16b is also configured similarly to the heat exchanger 16a. 1
8 is a drain tray installed below the heat exchangers 16a and 16b, 19 is a drain pipe connected to the drain tray 18, and 20 is a connection between the heat exchanger 16b, the distribution header 9 of the evaporator 1, and the refrigerant pump 10. 21 is a refrigerant pipe that connects the heat exchanger 16b and the auxiliary distribution header 28 of the evaporator 1; 22 and 23 are switching valves provided in the refrigerant pipes 20 and 21, respectively;
24 is an auxiliary heat exchanger provided in the low-temperature regenerator 4, 25 is a heat medium pipe that connects the auxiliary heat exchanger 24 and the heat exchanger 16a, and 26 and 27 are heat medium tanks provided in the refrigerant pipe 25. and a gate valve.

Next, the operation and effects of this embodiment having the above-described configuration will be explained.

During cooling operation, the gate valve 22 is set to the closed state and the gate valve 27 is set to the open state. Then, the heat medium in the heat medium tank 26 is introduced into the heat transfer tube _16a2 via the gate valve 27, the heat medium pipe ₂₅ , and the inlet header 16a1, and exchanges heat with the combustion exhaust gas of the boiler _3a flowing outside the heat transfer tube 16a2. It becomes heat medium vapor at 90℃.
This heat medium vapor flows into the auxiliary heat exchanger 24 provided in the low temperature regenerator ₄ through the outlet header 16a4, exchanges heat with the solution in the low temperature regenerator 4 and is condensed, and then flows into the heat medium tank 26. be returned. In this way, the heat of the exhaust gas from the boiler 3a is recovered to the solution in the low temperature regenerator 9.

Usually, the solution temperatures in the low-temperature regenerator 4 and the high-temperature regenerator 3 are 80-90°C and 130-160°C, respectively, so the exhaust gas temperature in the boiler 3a is higher than the solution temperature in the high-temperature regenerator 3. Further, the exhaust gas temperature after heat exchange in the heat exchanger 16a is also higher than the solution temperature in the low temperature regenerator 4. For example, the exhaust gas from boiler 3a
If the exhaust gas temperature of the heat exchanger 16a is 200° C. and 100° C., approximately 5% of heat can be recovered, depending on the fuel and combustion conditions, and the boiler efficiency can be substantially improved.

Furthermore, since the temperature of the exhaust gas after heat exchange can be maintained at 80 to 90° C. or higher in the heat exchanger 16a, there is no possibility that moisture in the exhaust gas will condense on the heat exchanger 16a. Further, at the start of operation, since the boiler 3a is cold, moisture in the exhaust gas condenses, but since it is only for a short time, the effect on corrosion of the equipment is small.

On the other hand, during heating operation, the gate valve 22 and the cooling/heating switching valve 15 are further opened, the supply of cold water to the cold water pipe 1a is stopped, and the cooling water pipes 2a, 5a are stopped.
Connect to the hot water system. In this case, the refrigerant is in the evaporator 1
After the pressure is increased by the refrigerant pump 10, the pipe 20
It is introduced into the heat exchanger 16b through the evaporator 1, and after being heated by exchanging heat with the exhaust gas, it passes through the piping 21 and is distributed from the auxiliary distribution header 28 of the evaporator 1 onto the group of heat transfer tubes (cold water tubes) 1a of the evaporator 1. . A portion of the refrigerant flashes and is introduced into the absorber 2 where it is absorbed into the solution.

The temperature of the refrigerant in the evaporator 1 is higher than that in the refrigeration cycle, at about 20°C. The reason is that hot water flows in the cooling water pipe 2a of the absorber 2,
This is because in order to heat hot water, it is necessary to raise the saturation temperature of the solution. Further, in the heat exchanger 16b, the exhaust gas is cooled to about 40 to 20°C, so a large amount of condensed water is generated, and this condensed water is collected in the drain tray 18 and then discharged from the drain pipe 19.

Recently, water injection burners and the like have been commercially available to reduce NOx, but when such burners are used, a large amount of heat is recovered in the heat exchanger 16b.
Further, since there is a large amount of condensed water from the exhaust gas, the pH can be maintained high, which is preferable in terms of durability of the heat exchanger 16b.

Furthermore, in this embodiment, a heat exchanger 16b for recovering heat to the absorber 2 via the evaporator 1 is disposed downstream of the heat exchanger 16a for recovering heat to the refrigerant of the low-temperature regenerator 4. There is no need to operate the gate valve 27 at times. Furthermore, since the heat load on the heat exchanger 16b is smaller than that in the case of a single unit, a small amount of refrigerant circulation is required to make the refrigerant inlet and outlet conditions of the heat exchanger 16b similar, which reduces the load on the refrigerant pump 10. be able to. On the other hand, if the refrigerant circulation amount is the same, the heat exchanger 16b can be made more compact by the amount of the temperature drop of the outlet refrigerant of the heat exchanger 16b.

In another embodiment shown in FIGS. 4 and 5, the heat exchanger 16 includes a heat exchanger tube 16A connected to an auxiliary heat exchanger 24, and a heat exchanger tube 16B connected to an evaporator (not shown). It differs from the embodiment shown in FIGS. 2 and 3 in that it is configured with plate fins 16C provided perpendicular to the heat exchanger tubes 16A and 16B, and the other configurations are the same, so drawings and explanations will be omitted. .

With this configuration, by closing the gate valve 27 and stopping the supply of refrigerant to the heat transfer tube 16A during cooling operation, the heat transfer tube 16A connected to the auxiliary heat exchanger 24 can be used as the entire plate fin 16C as a heat exchanger. It can be used effectively. On the other hand, during heating operation, by closing the gate valve 22 and stopping the supply of refrigerant to the heat transfer tubes 16B, the heat transfer tubes 16B connected to the evaporator and the entire plate 16C can be effectively used as a heat exchanger.

Also, in the embodiment (FIG. 2), two heat exchangers 16a and 16b are required, but in this embodiment, one heat exchanger is required.
Since only one heat exchanger 16 is required, it can be made compact. Further, in the embodiment described above, the heat exchanger 16b is inactive during cooling operation, but in this embodiment, the heat exchanger 16 can be used effectively in both cooling and heating, so that the utilization rate can be improved.

Another embodiment shown in FIGS. 6 and 7 has the following points: a heat exchanger 16a is connected to a heating pipe 4a of a low temperature regenerator 4 via a heat medium tank 26 and a throttle valve 27;
That is, this embodiment differs from the embodiment shown in FIG. 2 in that the heating tube 4a serves as an auxiliary heat exchanger, and the other structures are the same, so a description thereof will be omitted.

In the embodiment configured in this manner, the dryness of the steam generated in the steam pipe 29 is adjusted by adjusting the throttle valve 27, and the liquid head of the heat medium formed by the heat medium tank 26 and the throttle valve 27 is , the heat medium can be circulated by ensuring a pressure difference due to the flow resistance of the heating tube 4a. In this embodiment, the heating tube 4a of the low-temperature regenerator 4 also serves as an auxiliary heat exchanger, which has the advantage of simplifying the structure and reducing costs.

As explained above, according to the present invention, the boiler efficiency can be significantly improved by recovering the heat of the exhaust gas into the solution of the regenerator. In addition, the water in the exhaust gas is actively condensed and condensed to raise the pH, so the heat exchanger will not be corroded by condensed water.

[Brief explanation of drawings]

Fig. 1 is a system diagram of a conventional multi-effect absorption type water chiller/heater, Fig. 2 is a system diagram of a multi-effect absorption type chiller/heater of the present invention, and Fig. 3 is a detailed diagram of the heat exchanger of Fig. 2. FIG. 4 is a system diagram showing the main parts of another embodiment of the present invention, FIG. 5 is a detailed diagram of the heat exchanger shown in FIG. 4, and FIG.
The figure is a system diagram of another embodiment of the present invention, and FIG. 7 is a detailed diagram of the heat exchanger of FIG. 6. 3...High temperature regenerator, 4...Low temperature regenerator, 4a...
... Heater, 16, 16a, 16b ... Heat exchanger,
17...Exhaust path, 20, 21...Refrigerant pipe, 24...
...Auxiliary heat exchanger, 25... Heat medium pipe.

Claims (1)

[Claims] 1. High temperature regenerator, low temperature regenerator, condenser, absorber,
The high-temperature regenerator is equipped with an evaporator, a heat exchanger, and a pump, and has a combustor that heats the high-temperature regenerator, and these are operatively connected to operate as an absorption water cooler or an absorption water heater. A heat recovery heat exchanger is provided in the combustion exhaust gas flow path, a heat medium is heated and boiled by the heat recovery heat exchanger, and the heated and boiled heat medium is provided in a low-temperature regenerator. A multi-effect absorption type cold/hot water machine characterized by being provided with a heat medium pipe that is introduced into the heat exchanger, condenses and liquefied, and returns the heat medium to the heat recovery heat exchanger. 2. The multi-effect absorption type refrigerant according to claim 1, characterized in that a refrigerant pipe is provided that introduces refrigerant from the evaporator into the heat recovery heat exchanger during heating, exchanges heat, and returns the refrigerant to the evaporator again.・Hot water machine. 3. The multi-effect absorption type cooling system according to claim 2, characterized in that the heat recovery heat exchanger is composed of a header, a heat transfer tube, and plate fins intersecting with the header.
Hot water machine. 4 High temperature regenerator, low temperature regenerator, condenser, absorber,
The high-temperature regenerator is equipped with an evaporator, a heat exchanger, and a pump, and has a combustor that heats the high-temperature regenerator, and these are operatively connected to operate as an absorption type water chiller or an absorption type water heater. A heat recovery heat exchanger is installed in the combustion exhaust gas flow path of the regenerator, and the heat medium is heated and boiled by the heat recovery heat exchanger on the combustion exhaust gas inlet side.The heated and boiled heat medium is then transferred to the high-temperature regenerator. A multi-effect absorption type cold/hot water machine characterized by being provided with a heat medium pipe that mixes the generated refrigerant vapor and introduces it into a low-temperature regenerator, and circulates a part of the condensed refrigerant to the heat recovery heat exchanger. .